TWI703209B - Mold lubricating oil used to produce high-density sintered body, spray coating device of mold lubricating oil, powder compact molding device equipped with spray coating device, compact powder molding method using the device, and obtained by the method Sintered body - Google Patents

Abstract

The present invention is in view of the above situation, and its purpose is to Provide: excellent quick-drying, mold lubricants, spray coating device, and powder compact forming device that can uniformly coat the oil film from a small amount of coating to achieve high-speed forming and arbitrary powder compaction Shaped compacted body forming.

The present invention is about containing: carbon number 7~18 Hydrocarbon solvents, and oiliness improvers or extreme pressure agents for mold lubricants. Furthermore, in the present invention, a mold lubricating oil having a hydrocarbon solvent content of 50 to 98% by mass is preferable.

Description

Mold lubricating oil used to produce high-density sintered body, spray coating device of mold lubricating oil, powder compact molding device equipped with spray coating device, compact powder molding method using the device, and obtained by the method Sintered body

The present invention relates to a sintered body such as a sintered alloy obtained by high-temperature sintering of a compressed powder body by placing a metal powder in a mold, and a mold lubricant and mold lubrication for achieving a higher density of the sintered body Oil spray coating device, powder compact molding device equipped with spray coating device, etc.

As well known, powder metallurgy is a metal processing method in which metal powder flowing into a mold made of a special iron steel material is compacted by high pressure to form a compact and sinter the compact.

For example, in iron-based powder metallurgy, the iron powder is compressed and solidified by a high pressure of 500~1000MPa, and the compacted powder body is sintered at 600~1250℃.

Powder metallurgy is a cutting process that does not require deburring after forming. Therefore, it is suitable for the metal processing method of net shape. And, with powder The parts produced by metallurgy can be used as new parts by using two or more combinations, or by combining with parts made by other metal processing methods. Therefore, the parts produced by powder metallurgy are used in complex-shaped parts such as automobile parts and home appliances, and are used in multi-functional parts such as gears, pulleys, or magnetic materials.

In the process of compressing the metal powder in the mold, in order to reduce the wear between the metal powder and the mold, the metal powder is mixed with a mixed lubricant such as metallic alkali in advance. In addition, some solid lubricants for molds that are directly applied to the mold are used. In these mixed lubricants and solid lubricants for molds, there is no big difference in the lubricating composition. Generally, stearic acid or stearates (also called metal alkaloids) or waxes are used. Solid lubricants.

In the conventional powder metallurgy technology, from the viewpoint of ease of implementation and ease of mass production, it is generally adopted: for the metal powder, about 1% of the mixed lubricant is blended, and the metal powder compact is sintered. method.

However, if the mixed lubricant is excessively blended, the fluidity of the metal powder will be hindered, and the molded compact has a problem that it cannot be compacted. In addition, when the metal powder compact is sintered, the mixed lubricant is removed and voids are generated, so there is a problem that the density of the compact is low. Furthermore, in the sintering process, since a large amount of gas including carbon dioxide and zinc oxide is generated, there is also a problem of deterioration of the working environment.

The solution to the above-mentioned problem is proposed: the temperature of the mold is set to about 95°C, and the inner surface of the mold will serve as the melting point of the mold lubricant Stearic acid powder at 70°C is electrostatically applied by a friction charging method, and the stearic acid powder is melted by heat to form a liquid lubricating film (for example, refer to Patent Document 1).

However, a liquid lubricating film formed by melting a solid lubricant has a high viscosity and is difficult to dry. Therefore, liquid slack is easily caused and uneven streaks are formed in the oil film, which causes and disadvantages of poor lubrication. Moreover, in this method, the lubricant for the mold will be coated slightly, and there are also: the lubricant for the mold will adhere to the mold, or the dimensional accuracy of the sintered body will be reduced, or the sintered body will be colored and the appearance will be poor. Disadvantages. In addition, a certain method in which it is necessary to apply a slightly larger amount of lubricant for the mold has a disadvantage that it is difficult to produce compacts of arbitrary shapes, such as compact compacts and compact compacts.

Other countermeasures are proposed: a method of filling a powder metallurgical powder with lubricant blended in a molding die coated with a lubricant on the inner wall, and compressing and molding by temperature or heat (for example, refer to Patent Document 2 ).

However, in the method of heating and melting the lubricant applied to the mold, the time until the lubricant is melted and the time from melting to forming a uniform oil film have disadvantages of being too long. As a result, the cycle time for forming the powder compact becomes longer, and the production efficiency of the sintered body decreases. In addition, the method of using such a solid or powder lubricant is not suitable for the application of a small amount of lubricant, and has the disadvantage that it cannot produce a compact powder compact and a compact powder compact.

And disperse the powdered lithium stearate in water and coat it on The method of mold is also proposed (for example, refer to Non-Patent Document 1). However, in this method, since it takes time until the water evaporates, the cycle for forming the green compact becomes longer, and the production efficiency of the sintered body decreases. In addition, powdered lubricants may agglomerate or form uneven streaks in the oil film, causing poor lubrication.

〔Literature technical literature〕 〔Patent Literature〕

[Patent Document 1] JP 11-140505 A

[Patent Document 2] JP 2000-199022 A

〔Non-patent literature〕

[Non-Patent Document 1] "Powder and Powder Metallurgy Vol.62 No.3" by Powder and Powder Metallurgy Association, Ming Pao, March 15, 2015, p.95~100

The present invention is in view of the above situation, and its object is to provide a mold lubricant, a spray coating device, and a powder compact molding device that has excellent quick-drying properties and can form a uniform oil film with a small amount of coating. High-speed molding of powder and molding of compacted powder of arbitrary shape.

And its purpose is to provide a method of using the above-mentioned mold lubricating oil, spray coating device, and powder compact forming device, even if mixing is reduced Mixed lubricants such as metal powders, metal limes, etc., will not cause wear, and can produce sintered bodies at high speed.

A further purpose is to reduce the amount of voids generated after sintering by reducing the mixed lubricants such as metal alkaloids mixed with the metal powder, and to achieve high density of the sintered body by high pressure molding. Another purpose is to reduce the generation of gases such as carbon dioxide and zinc oxide and reduce the deterioration of the working environment.

The mold lubricating oil of the present invention contains a hydrocarbon solvent having 7 to 18 carbon atoms, an oiliness improver and/or an extreme pressure agent.

In the present invention, further, the content of the hydrocarbon solvent is preferably 50 to 98% by mass of the mold lubricant.

In the present invention, further, the content of the oiliness improver and/or extreme pressure agent is preferably 20% by mass or less of mold lubricant.

In the present invention, further, the hydrocarbon solvent is one or more solvents selected from the group consisting of paraffinic hydrocarbon solvents, olefinic hydrocarbon solvents, naphthenic hydrocarbon solvents, and aromatic hydrocarbon solvents The mold lubricant is better.

In the present invention, the oiliness improver is preferably a mold lubricating oil of one or more compounds selected from the group consisting of silicon, animal and vegetable oils and fats, and higher fatty acid esters.

The present invention, further, the extreme pressure agent is composed of phosphate ester, TCP, sulfide vulcanized oil, MoDTC, ZnDTP, and MoDTP A mold lubricant of one or more compounds selected from the group is preferred.

The spray coating device of the present invention is further provided with a needle roller having an inclined portion having a substantially truncated cone shape, and a needle receiving portion having an inclined portion having a substantially truncated cone shape, the needle roller and the needle receiving portion, It can be slightly fitted into each of the approximately truncated cone-shaped inclined parts, and the mold lubricant is passed between the slightly fitted needle roller and the needle roller receiving part.

The spray coating device of the present invention further includes: a needle tip portion on the narrowing side of the substantially truncated cone-shaped inclined portion formed in the needle roller, and a substantially truncated cone-shaped portion with the needle roller receiving portion The needle roller receiving hole connected to the narrowed side of the inclined portion is connected to the oil supply pipe that supplies the mold lubricant to the spray coating device on the side facing the needle roller receiving portion. The needle bearing hole and the needle tip can be slightly fitted. The diameter of the needle bearing hole in the part slightly fitted with the needle tip is 0.6~1.8mm, and the diameter of the needle tip is 0.5~1.7mm. Preferably, the difference between the diameter of the needle bearing hole and the diameter of the tip of the needle is 0.05 to 0.4 mm.

The spray coating device of the present invention further preferably sprays the mold lubricant in an amount of 0.01-10 ml/time.

The spray coating device of the present invention further has a plurality of air supply holes for supplying air and spray nozzles for supplying oil from the mold lubricant to the mold. The air supply holes are plurally provided around the oil supply holes for air supply The hole and the oil supply hole are arranged at positions that are twisted with each other. When the angle formed by the air supply hole and the oil supply hole is measured from a direction substantially perpendicular to the plane containing one air supply hole, the air supply hole and the oil supply hole are The angle formed is preferably 20 to 40 degrees.

The powder compact forming apparatus of the present invention is provided with: a coating means for coating mold lubricant with a spray coating device, a filling means for filling a mold coated with mold lubricant with metal powder, and The metal powder presses the forming means for forming the compact, the extraction means for pulling the formed compact upwards from the mold, and the extraction means for extracting the drawn compact from the upper part of the mold. The extraction means and spray coating device move in the direction toward the upper part of the mold, which is the extraction direction, in the state before extraction. The extraction means is arranged in the extraction direction ahead of the spray coating device. The extraction means and the spray coating device move in the extraction direction. The extraction means extracts the pressed powder through the upper part of the mold. The spray coating device applies the mold lubricant to the mold when it reaches the upper part of the mold. The present invention relates to a compacted powder forming apparatus as described above.

In the powder compact forming apparatus of the present invention, further, the extraction means, the spray coating device, and the filling means move in conjunction with the direction toward the upper part of the mold, that is, the extraction direction, in the state before extraction. The filling means is arranged behind the spray coating device along the extraction direction. By moving the spray coating device and the filling means in the extraction direction in conjunction, the filling means is a spray coating device that coats the mold lubricant on the mold Then, when reaching the upper part of the mold, the mold is filled with metal powder. The present invention is preferable as the above-mentioned compacted powder forming device.

The powder compact molding apparatus of the present invention further includes a wiping means for wiping the metal powder existing above the mold among the metal powder filled in the mold. The extraction means and spray coating device are alternately moved back and forth between the extraction direction and the opposite direction of the extraction direction. Sequentially formed compressed powder body is extracted, and the mold lubricant is applied to the mold repeatedly. The rubbing and cutting means are arranged in the extraction direction behind the spray coating device, and the spray coating device and the rubbing and cutting means are linked to extract. Moving in the opposite direction of the direction will wipe and cut the metal powder filled in the mold. The present invention is preferable as the above-mentioned compacted powder forming device.

The method for forming a powder compact of the present invention includes: a coating process of applying a mold lubricant by a spray coating device, a filling process of filling a mold coated with a mold lubricant with metal powder, and a filling process The molding process in which the metal powder is pressed to form the compact, and the extraction process in which the molded compact is pulled out higher than the mold, and the drawn compact is extracted from the upper part of the mold by extraction means The extraction process. The extraction means and spray coating device move in the direction toward the upper part of the mold, that is, the extraction direction, in the state before extraction. The extraction means is arranged in the extraction direction ahead of the spray coating device. The means and spray coating device move in the extraction direction. The extraction means extracts the compressed powder through the upper part of the mold. The spray coating device applies the mold lubricant to the mold when it reaches the upper part of the mold. The present invention relates to a method for forming a compact as described above.

The present invention relates to a sintered body obtained by sintering a powder compact formed by the aforementioned powder compact forming method.

According to the mold lubricant of the present invention, since it is excellent in quick-drying, a uniform oil film can be formed by applying a small amount of coating. With lubricating oil, it can realize high-speed molding of compacts and compact compacts of arbitrary shapes. In addition, by using the above-mentioned mold lubricant, even if a mixed lubricant such as a metallic alkali mixed with the metal powder is reduced, wear does not occur, and a sintered body can be produced at a high speed.

Furthermore, by reducing the amount of mixed lubricants such as metal alkaloids mixed with the metal powder, voids generated after sintering can be reduced, and the sintered body can be formed by high pressure to increase the density. In addition, the generation of gases such as carbon dioxide and zinc oxide can be reduced, and the deterioration of the working environment can be reduced.

10‧‧‧Spray coating device

11‧‧‧Oil volume adjustment knob

12‧‧‧Spring Chamber

13‧‧‧Spring

14‧‧‧Fixed ring

15‧‧‧Needle roller

15S‧‧‧Needle diameter part

15L‧‧‧Large diameter part of needle roller

15T‧‧‧Needle tip

15I‧‧‧Needle roller inclined part

16‧‧‧Needle Roller Socket

16S‧‧‧Needle roller socket

16P‧‧‧Needle roller socket

18‧‧‧Spray body

19‧‧‧Jet nozzle

20‧‧‧Spray nozzle cap

21‧‧‧Air Supply Road

22‧‧‧Air Branch Road

23‧‧‧Air supply hole

24‧‧‧Air spray ditch

31‧‧‧Oil supply hose

32‧‧‧Oil Supply Pipe

33‧‧‧Oil hole

40‧‧‧Feeder

41‧‧‧Outer Wall

42‧‧‧Cutting part

43‧‧‧Extraction Department

50‧‧‧Metal powder

51‧‧‧Pressed powder

60‧‧‧Mould plate

70‧‧‧Mould

80‧‧‧Oil film

91‧‧‧Upper punch

92‧‧‧Down punch

[Figure 1] An schematic view (a) of a cross-sectional view of a spray coating device for spraying mold lubricant of the present invention, and a schematic view (b) of a cross-sectional view of a spray nozzle in the spray coating device.

[Figure 2] A schematic diagram of a perspective view of a spray nozzle in a spray coating device.

[Figure 3] A schematic diagram of a cross-sectional view of the compact forming apparatus of the present invention, and a schematic diagram showing a coating mechanism, a filling mechanism, a wiping mechanism, a forming mechanism, an extraction mechanism, and an extraction mechanism.

<Mold Lubricant>

According to the mold lubricant of the present invention, even if the mold is not heated, an oil film that maintains high strength can be formed on the surface of the mold. Moreover, the mold lubricating oil of the present invention can optimally exhibit lubricating performance even under high pressure. Hereinafter, the composition of the mold lubricant of the present invention will be described in detail.

The mold lubricating oil of the present invention contains a hydrocarbon solvent having 7 to 18 carbon atoms, and an oiliness improver or extreme pressure agent composition. The mold lubricating oil is made of the above composition, because the quick-drying property becomes high and the uniform oil film is formed, so it can realize the high-speed molding of the powder compact and the molding of the powder compact of any shape. Moreover, by using the above-mentioned mold lubricant, even if the mixed lubricant mixed with the metal powder is reduced, wear will not occur, and the sintered body can be produced at a high speed.

Furthermore, the use of the above-mentioned mold lubricant with good lubricity and being able to be applied in a small amount can reduce the amount of mixed lubricant mixed with the metal powder, so the voids after sintering can be reduced, and it can be formed by high pressure to achieve sintering. High density of the body. In addition, the generation of gases such as carbon dioxide and zinc oxide can also be reduced, and the deterioration of the working environment can be reduced.

In addition, the mold lubricating oil of the present invention has excellent quick-drying properties and easily forms an oil film at room temperature, so there is no need to heat the mold. Therefore, the mold lubricant of the present invention can also be used in molds whose surface temperature is 40°C or less, for example. In this way, since the time for heating the mold and the time for melting the lubricant used in the mold are not required, the molding process of the powder compact can be speeded up.

The mold lubricant of the present invention is as described later, because it can be applied in a small amount. In a general coating method, a spray coating device is used to apply Coating is better. By applying the mold lubricating oil of the present invention to the mold by a spray coating device, it is possible to easily form compact powder bodies of any shape, such as compact powder bodies and fine-shaped powder bodies.

In order to apply the mold lubricant to the spray coating device, it is better to optimize the dynamic viscosity of the mold lubricant from the viewpoint of achieving stable spray. The dynamic viscosity at 40°C of the mold lubricant is preferably less than 2~100mm ² /s. If the dynamic viscosity at 40°C of the mold lubricant is less than 2 mm ² /s, the spray pump of the spray coating device tends to wear. If the dynamic viscosity at 40°C of the mold lubricant exceeds 100 mm ² /s, it tends to be difficult to spray the mold lubricant.

When the spray coating from the stable viewpoint, the movable mold 40 ℃ viscosity of the lubricating oil, is ² ~ 50mm 2 / s more preferably, ² ~ 20mm 2 / s is further preferable. In order to spray coating with the dynamic viscosity of the mold lubricant at 40°C under 100mm ² /s, the mold lubrication should be adjusted appropriately in the air flow rate, air pressure, gear pump, etc. pressure delivery device, or spray coating device The diameter of the oil supply hole where the oil is sprayed is preferable.

And if the dynamic viscosity of the mold lubricant at 40°C exceeds 10mm ² /s, even if the mold lubricant is applied to the mold and the metal powder is filled into the mold, the mold lubricant will interact with the metal powder near the opening of the mold. Contact, and tends to easily form agglomerates (lumps). If agglomerates are formed near the opening of the mold, the metal powder cannot be filled to the back side of the mold, and it tends to be difficult to form the compact into the desired shape. Therefore, from the above-mentioned point of view, the dynamic viscosity at 40°C of the mold lubricant is preferably 10 mm ² /s or less.

The dynamic viscosity of the mold lubricant can be measured according to Ubbelohde viscometer (ASTM D445), for example.

In addition, in the mold lubricant, in addition to the hydrocarbon solvents, oily improvers, and extreme pressure agents described later, within the scope that does not violate the spirit of the present invention, oxidation inhibitors, metal inert agents, rust inhibitors, or Additives such as defoamers may also be used.

(1) Hydrocarbon solvent

The solvent in the mold lubricant must evaporate quickly after the mold lubricant is applied to the mold. Because the solvent in the mold lubricating oil evaporates quickly, the lubricating components in the mold lubricating oil form a high-strength oil film to ensure the best lubricity.

On the other hand, when the solvent in the mold lubricating oil is not easy to evaporate, or even if it evaporates but the solvent remains, the mold lubricating oil will flow down without forming a strong oil film, which reduces the lubricity.

Therefore, the solvent in the mold lubricating oil is one that evaporates and does not remain easily, that is, a solvent with high drying properties is preferable. In addition, from the viewpoint of preventing the health of the operator, the solvent in the mold lubricant has a high saturated hydrocarbon content and can suppress the sulfur content and nitrogen content at an extremely low level. good.

The hydrocarbon solvent used in the solvent of the mold lubricating oil of the present invention is a liquid at room temperature. Moreover, the carbon number of the hydrocarbon solvent is 7-18, preferably 10-15. If the carbon number of the hydrocarbon solvent is less than 7, the dryness is too high, so the adhesion to the mold may deteriorate, and there is a risk of fire. Sexual increase. In addition, if the carbon number of the hydrocarbon solvent exceeds 18, it will be difficult for the solvent to evaporate and the dryness will be reduced. As for the viscosity of the oil film formed by the oiliness improver and extreme pressure agent described later, the low-viscosity undried part of the solvent will decrease. The lubricity of the oil film will decrease and cause wear.

As described above, the hydrocarbon solvent used in the present invention must have the best drying properties, and if the hydrocarbon solvent has the best drying properties, it can be used in the present invention. Hydrocarbon solvents with carbon number 7-18, especially those with the best drying properties, are particularly suitable as a solvent for mold lubricants.

Hydrocarbon solvents are the most quality component in mold lubricants, that is, the main component is better. The content of the hydrocarbon solvent is preferably 50 to 98% by mass, more preferably 60 to 98% by mass, and even more preferably 60 to 95% by mass based on the total amount of the mold lubricant.

If the content of the hydrocarbon solvent is less than 50% by mass, the blending ratio of the oiliness improver or the extreme pressure agent described later increases, and therefore the oil film on the inner wall surface of the mold tends to be difficult to dry. If the content of the hydrocarbon solvent exceeds 98% by mass, the oil film of the mold lubricating oil is thin, and the lubricity of the mold lubricating oil tends to decrease.

Although the type of hydrocarbon solvent is not particularly limited, for example, paraffin-based hydrocarbon solvents, olefin-based hydrocarbon solvents, naphthenic-based hydrocarbon solvents, or aromatic-based hydrocarbon solvents can be exemplified.

Paraffin-based hydrocarbon solvents contain saturated hydrocarbon solvents that are not ring-shaped but locked. Compared with other hydrocarbon solvents, they are less likely to cause health problems for operators and have less viscosity change due to temperature. Therefore, by using paraffin-based hydrocarbon solvents as the solvent for mold lubricants Use it to spray the mold lubricant stably.

In addition, paraffin-based hydrocarbon solvents have low reactivity and high chemical stability compared with other hydrocarbon solvents. Therefore, by using a paraffin-based hydrocarbon solvent as a solvent for the mold lubricant, it is difficult for the lubricant components in the mold lubricant to deteriorate.

From the above viewpoints, among the hydrocarbon solvents, paraffin-based hydrocarbon solvents are particularly preferred among the solvents used in mold lubricants.

The type of paraffin-based hydrocarbon solvent is not particularly limited. For example, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, or pentadecane can be exemplified Alkane solvents.

The olefin-based hydrocarbon solvent is a solvent containing a double-bonded hydrocarbon. Although the type of olefin-based hydrocarbon solvent is not particularly limited, for example, 1-heptene, 1-octene, 1-nonene, 1-decene, etc. can be exemplified.

The naphthenic hydrocarbon solvent is a solvent containing a compound having at least one saturated aliphatic ring in the molecule, and has a higher drying property than the aromatic hydrocarbon solvent described later. Although the type of the cycloalkane hydrocarbon solvent is not particularly limited, for example, cyclopentane, cyclohexane, or cyclooctane can be exemplified.

The aromatic hydrocarbon solvent is a solvent containing a compound having at least one aromatic ring in the molecule. Although the kind of aromatic hydrocarbon solvent is not specifically limited, for example, triene, xylene, etc. can be mentioned.

And hydrocarbon solvents, petroleum-based hydrocarbon solvents, hydrocarbon solvents derived from natural products, or chemically synthesized hydrocarbon solvents can be used Various persons.

In addition, as the hydrocarbon solvent, the above-mentioned solvents may be used alone or in plural. In addition, the hydrocarbon solvent may include additives, impurities, etc., within a range that does not violate the spirit of the present invention.

(2) Oiliness improver

By adding an oil improver to the mold lubricant, the lubricity between the powder compact and the mold can be ensured. Oiliness improver refers to a compound with polarity, and its polar part is physically adsorbed to the mold to form an oil film, so it acts as a buffer between the powder compact and the mold to reduce friction. In addition, the oiliness improver is preferably one with high affinity for solvents.

The content of the oiliness improver is the total amount of the mold lubricant, preferably 20% by mass or less, more preferably 2-18% by mass, and still more preferably 2-15% by mass. If the content of the oiliness improver exceeds 20% by mass, the oil film becomes excessively thick, and there is a tendency that voids generated after sintering tend to increase. In addition, the dynamic viscosity of mold lubricants also tends to increase, making stable spray coating difficult. In addition, the oiliness improver tends to adhere easily to the sintered body. If the content of the oiliness improver is less than 2% by mass, the oil film becomes insufficient, which may cause wear and the like.

Although the type of oiliness improver is not particularly limited, for example, silicon, animal and vegetable fats and oils, or higher fatty acid esters can be exemplified.

The type of silicon, although not particularly limited, for example, examples can be given Modified silicon such as phenol modified silicon, methylstyrene modified silicon, alkyl modified silicon, or alkyl aralkyl modified silicon, or dimethyl silicone oil.

The types of animal and vegetable oils and fats are not particularly limited. For example, rapeseed oil, soybean oil, coconut oil, palm oil, tallow, or lard can be cited.

The types of higher fatty acid esters are not particularly limited. For example, monovalent alcohol esters or polyhydric alcohol esters of higher fatty acids such as coconut oil fatty acid, oleic acid, stearic acid, lauric acid, palmitic acid, or tallow fatty acid can be cited. Valence alcohol esters and so on.

In addition, as the oiliness improver, the above-mentioned compound may be used alone or in plural. In addition, the oiliness improver may include additives, impurities, etc., within a range that does not violate the spirit of the present invention.

(3) Extreme pressure agent

By adding an extreme pressure agent to the mold lubricant, the wear between the powder compact and the mold can be reduced under high pressure loads. Extreme pressure agent refers to the formation of a soft oil film by a chemical reaction between the powder compact and the mold. By reducing the direct contact between the powder compact and the mold, it can prevent The meaning of wear and abrasion compounds. In addition, the extreme pressure agent is preferably one with high affinity for the solvent.

The content of the extreme pressure agent is the total amount of the mold lubricant, preferably 20% by mass or less, more preferably 0.5-18% by mass, and still more preferably 0.5-15% by mass.

If the content of the extreme pressure agent exceeds 20% by mass, the dynamic viscosity of the mold lubricant becomes high, and stable spray coating tends to be difficult. In addition, the extreme pressure agent also tends to adhere easily to the sintered body. If the content of the extreme pressure agent is less than 2% by mass, the oil film may become insufficient, which may cause wear and the like.

The type of extreme pressure agent is not particularly limited. For example, sulfide vulcanized oil such as dialkyl pentasulfide, phosphate ester, TCP (tricresyl phosphate), MoDTC (molybdenum dithiocarbamate), ZnDTP (Zinc dialkyl dithioate), or MoDTP (molybdenum dithiophosphate), etc.

In addition, as the extreme pressure agent, the above-mentioned compound may be used alone or in plural. In addition, the extreme pressure agent may include additives, impurities, etc., within a range that does not violate the spirit of the present invention.

And by using oiliness improver and extreme pressure agent together, high lubricity and wear resistance can be expected. When the oiliness improver and the extreme pressure agent are used together, the total amount of the oiliness improver and the extreme pressure agent is based on the total amount of the mold lubricant, preferably 20% by mass or less, more preferably 2-18% by mass, 2-15 The mass% is further preferred.

<Mold lubricant spray coating device>

Although the coating method of the mold lubricant of the present invention is not particularly limited, methods such as brush coating, roller coating, or spray coating by a spray coating device can be exemplified. Brush coating or roller coating is best from the viewpoint of thickly coating the mold lubricant on the mold, but it has advantages The thickness of the oil film formed by the mold lubricant tends to be uneven. In addition, since most of the molds used to mold the powder compacts are generally small, they tend to be difficult to coat in bristle coating and roller coating. Therefore, when the mold is coated with the mold lubricant, spray coating is preferably performed by a spray coating device.

For the spray coating device for spraying the above-mentioned mold lubricant, for example, the spray coating device 10 of FIG. 1 can be used.

The spray coating device 10 has: an oil volume adjustment knob 11, a spring chamber 12, a spring 13, a fixed ring 14, a roller needle 15, a needle roller socket 16, a spray body 18, a spray nozzle 19, a spray nozzle cap 20, and air The supply path 21, the air branch path 22, the air supply hole 23, the oil supply hose 31, the oil supply pipe 32, the oil supply hole 33, and the like.

The needle roller 15 has a needle roller small diameter portion 15S, a needle roller large diameter portion 15L, a needle roller inclined portion 15I, and a needle roller tip portion 15T. The needle roller small diameter portion 15S is connected to the needle roller large diameter portion 15L, and the needle roller inclined portion 15I is connected to the needle roller tip portion 15T, and each is arranged in a substantially linear shape. In this embodiment, the diameter of the needle roller small diameter part 15S is about 3.0 mm, the diameter of the needle roller large diameter part 15L is about 10.0 mm, and the diameter of the needle roller tip part 15T is about 0.65 mm. In addition, the needle roller receiver 16 has a needle roller receiving portion 16S and a needle roller receiving hole 16P.

The oil volume adjustment knob 11 is a knob for constant control of the oil volume. The oil volume adjustment knob 11 is provided with a spring chamber 12, and in the spring chamber 12, a spring 13 is incorporated. In addition, the spring 13 is wound around the small diameter portion 15S of the needle roller, and can compensate for the vertical movement of the needle roller 15. When using spring 13 The load is preferably 1.0 to 3.0N.

After adjusting the amount of sprayed oil by the oil amount adjustment knob 11, the oil amount adjustment knob 11 is fixed by the fixing ring 14. By fixing the oil quantity adjusting knob 11 by the fixing ring 14, the quantity of oil per spray can be constant.

The needle roller 15 has a needle roller inclined portion 15I constituted by an approximately truncated cone-shaped inclined portion, and the needle roller receiving portion 16 has a needle roller receiving portion 16S constituted by an approximately truncated cone-shaped inclined portion. Furthermore, the needle roller 15 and the needle roller receiving portion 16 can be slightly fitted into the needle roller inclined portion 15I and the needle roller receiving portion 16S, and the mold lubricant can pass through the needle roller inclined portion 15I and the needle roller receiving portion which can be slightly fitted. Between 16S.

The angle formed by the substantially truncated cone-shaped inclined portion of the needle roller inclined portion 15I is preferably 20 to 40 degrees. In addition, the angle formed by the substantially truncated cone-shaped inclined portion in the needle roller receiving portion 16S is the angle formed by the substantially truncated cone-shaped inclined portion in the needle inclined portion 15I, and is -5 to -1 degrees. good. In the needle roller inclined portion 15I and the needle roller receiving portion 16S, each of the approximately truncated cone-shaped inclined portions has the above-mentioned angle relationship, so that it is easy to finely adjust the amount of mold lubricant sprayed.

The spray coating device 10 has: a needle tip portion 15T on the narrowing side of a substantially truncated cone-shaped inclined portion formed in the needle roller inclined portion 15I, and a substantially truncated cone shape formed in the needle roller receiving portion 16S The needle roller receiving hole 16P connected to the narrowed side of the inclined portion. Furthermore, the needle roller receiving hole 16P is connected from the side facing the needle roller receiving portion 16S to the oil supply pipe 32 that supplies the mold lubricant into the spray coating device 10, so that the needle roller The receiving hole 16P and the needle tip 15T are slightly fitted.

At the fitting position of the needle bearing hole 16P and the needle tip 15T, the diameter of the needle bearing hole 16P is preferably 0.6~1.8mm, and the diameter of the needle tip 15T is 0.5~1.7mm. In addition, the difference between the diameter of the needle roller receiving hole 16P and the diameter of the needle tip 15T is preferably 0.05 to 0.4 mm. The needle roller receiving hole 16P and the needle roller tip portion 15T satisfy the above-mentioned conditions, so that a small amount of mold lubricant tends to be easily applied.

The needle roller receiving hole 16P is connected to the oil supply pipe 32 as described above to form a part of the oil supply pipe 32. An oil supply hose 31 for supplying mold lubricating oil is connected to an oil supply pipe 32. The needle roller receiving hole 16P forming a part of the oil supply pipe 32 is connected to the oil supply hole 33 provided in the injection nozzle 19. The air supply path 21 for supplying air is connected to the air branch path 22 and the air supply hole 23.

The air supply hole 23 is preferably inclined to the central axis of the spray nozzle 19 at 20-40 degrees. Since the air supply hole 23 is provided in the above-mentioned manner, it tends to be easy to spray the mold lubricant widely.

<How to spray mold lubricant>

By rotating the oil amount adjustment knob 11 counterclockwise, the spring chamber 12 rotates counterclockwise and moves to the side opposite to the needle roller large diameter portion 15L. As the spring chamber 12 moves to the side opposite to the needle roller large diameter portion 15L, the spring 12 incorporated in the spring chamber 12 is slowed down. By slowing down the spring 12 to decrease the elastic force of the spring 12, the needle roller large diameter portion 15L is moved to the side opposite to the needle roller receiver 16 side.

As the needle roller large diameter portion 15L moves to the side opposite to the needle roller receiver 16 side, the mating state of the needle roller 15 and the needle roller receiver 16 changes. As a result, the supply amount of mold lubricating oil per unit time that is supplied from the needle roller receiving hole 16P (oil supply pipe 32) to the oil supply hole 33 increases. As described above, the oil amount of the mold lubricating oil supplied from the oil supply hole 33 can be slightly increased.

By rotating the oil amount adjusting knob 11 counterclockwise, the spring chamber 12 rotates counterclockwise and moves toward the side of the needle roller large diameter portion 15L. As the spring chamber 12 moves to the side of the needle roller large diameter portion 15L, the spring 12 incorporated in the spring chamber 12 is compressed. By compressing the spring 12, the elastic force of the spring 12 is increased, and the needle roller large diameter part 15L is moved toward the needle roller receiver 16 side.

As the needle roller large diameter portion 15L moves toward the needle roller receiver 16 side, the fitted state of the needle roller 15 and the needle roller receiver 16 changes. As a result, the supply amount of mold lubricating oil per unit time that is supplied from the needle roller receiving hole 16P (oil supply pipe 32) to the oil supply hole 33 decreases. As described above, the amount of mold lubricant supplied from the oil supply hole 33 can be slightly reduced.

Air is introduced into the spray body 18 from the air supply path 21. In the air introduction operation, a solenoid valve is used. The air pressure of the supplied air is preferably 3 MPa or more. In addition, it is better to adjust the air pressure to a moderate air pressure using a regulator or the like to prevent the air pressure from being too high. When air flows into the air supply path 21 and the air branch path 22, the needle roller 15 is pushed up, and a gap is formed in the needle roller receiver 16, so that the mold lubricant can be supplied to the mold. In addition, the hydraulic pressure of the mold lubricant is preferably 0.1 to 1.0N.

The air supplied from the air supply path 21 also passes through the air branch path 22 and is supplied toward the needle roller large diameter portion 15L side. The pressure of the air supplied from the air branch passage 22 moves the needle roller large diameter portion 15L to the side opposite to the needle roller receiver 16 side. Also by this mechanism, the amount of mold lubricant is finely adjusted.

The air supplied from the air supply path 21 passes through the air supply hole 23 and the air spray groove 24 and is sprayed toward the outside of the spray body 18.

In the injection nozzle 19 provided with the air supply hole 23 and the oil supply hole 33, the air supply hole 23 is provided at six locations around the oil supply hole 33 (23a, 23b, 23c, 23d, 23e, and 23f in the second figure). ). The air supply hole 23 and the oil supply hole 33 are arranged at positions that are twisted to each other. When the angle formed by the air supply hole 23 and the oil supply hole 33 is measured from a direction perpendicular to a substantially plane including one air supply hole 23, The angle formed by the air supply hole 23 and the oil supply hole 33 is preferably 20-40 degrees. That is, when the air supply hole 23 and the oil supply hole 33 are viewed from the position where the end of one air supply hole 23 on the air supply path 21 side overlaps the oil supply hole 33, the air supply hole 23 and The angle formed by the oil hole 33 is preferably 20-40 degrees. The angle formed by the air supply hole 23 and the oil supply hole 33 satisfies the above-mentioned range, and when the air is sprayed from the air spray groove 24, a vortex is formed.

The air supplied from the air supply path 21 passes through the air supply hole 23 provided in the spray nozzle 19 and then passes through the spray nozzle 19 and the spray nozzle 19 The gap (0.3 to 1.5 mm) of the nozzle cap 20 flows and is sprayed from the air spray groove 24 while being swirled. When air is sprayed, the vicinity of the oil supply hole 33 is in a vacuum state, so the air introduces the mold lubricant from the oil supply hole 33. Therefore, the air and the mold lubricating oil are mixed into a mist and sprayed onto the mold 70.

The spray amount of the mold lubricant is preferably a small amount from the viewpoint of making the solvent of the mold lubricant easy to dry. The spray volume of mold lubricant is preferably 0.01-10ml/time, and 0.05-5ml/time is even better. If the spray amount of the mold lubricant is less than 0.01 ml/time, the formation of the oil film is insufficient, which tends to cause wear. If the spray amount of the mold lubricant exceeds 10 ml/time, the solvent of the mold lubricant tends to be difficult to evaporate.

In addition, the above-mentioned spray coating device 10 is not limited to only oil-based mold lubricants, but may spray the entire mold lubricant containing water-based ones.

Hereinafter, the powder compact forming apparatus shown in Fig. 3 will be described.

The type of metal powder 50 that can be applied to the compact forming apparatus of the present invention is not particularly limited. For example, iron, copper, nickel, chromium, tungsten, molybdenum, or stainless steel containing chromium and nickel in iron, etc. Alloy steel and other metals. In addition, in the mixture of the above-mentioned metals and the mixture of the above-mentioned metals, a mixture containing carbon for enhancing sintering strength and surface hardening may be used.

<Powder compact forming device>

The metal powder 50 filled in the mold 70 is formed into a powder compact molding apparatus for forming a compact 51, which is equipped with a spray coating device 10 to coat the mold lubricant with a coating means and The filling means for filling the metal powder 50 in the oil mold 70, the wiping means for wiping the metal powder 50 existing above the mold 70 among the metal powder 50 to be filled in the mold 70, and the metal powder to be filled 50 Press the forming means for forming the powder compact 51, and the extraction means for pulling the formed powder 51 toward the upper part of the mold 70, and extract the drawn powder 51 from the upper part of the mold 70 The means of extraction.

The filling means is located behind the coating means, and the extraction means is located forward of the coating means. In addition, the wiping and cutting means are arranged behind the coating means and in front of the filling means.

That is, in the powder compact forming apparatus of the present invention, the extraction means, the coating means, the rubbing means, and the filling means are arranged in this order, so that the feeder 40 faces upwards of the die plate 60 along the arrangement direction. It can slide back and forth.

In this embodiment, the spray coating device 10 constitutes the coating means, a part of the feeder 40 constitutes the filling means, the wiper section 42 constitutes the wiper means, and the die 70, the upper punch 91 and the lower punch 92 constitute the forming means. As a means, the lower punch 92 constitutes the extraction means, and the extraction part 43 constitutes the extraction means.

The feeder 40 has an opening toward the ground surface side of the die plate 60, and the entire ground surface side is formed by dropping the metal powder 50 to form a filling means.

The drop portion of the metal powder 50 may be a state in which the entire surface of the mold plate 60 is opened toward the ground surface side as in the present embodiment, or a portion of the ground surface side may be a state in which an opening is formed.

The upper part of the outer wall 41 that constitutes the feeder 40 is a method for confirming the remaining amount of the metal powder 50 inside the feeder 40. A part of the metal powder 50 may be made of a transparent member, or it may be opened without a member.

A part of the outer wall 41 facing the grounding surface side of the mold plate 60 is shaped like a frame. The metal powder 50 is held in this frame. The metal powder 50 becomes the front and back on the mold plate 60 with the feeder 40. Sliding appearance.

By using the powder compact molding apparatus as described above, spray coating of the mold lubricant and filling of the metal powder 50 into the mold 70 can be performed almost simultaneously. In addition, the molding of the compact 51 and the extraction of the compact 51 can be performed almost simultaneously. Therefore, the molding of the powder compact 51 described later can be made at a high speed, and a sintered body obtained by sintering the powder compact 51 can be mass-produced at high speed.

Hereinafter, the coating mechanism, filling mechanism, wiping mechanism, forming mechanism, pull-out mechanism, and extraction mechanism shown in Figure 3 will be described in accordance with process A to process E.

[Process A] (Coating mechanism)

With extraction means, spray coating device 10, and filling hand The stage feeder 40 slides on a substantially flat mold plate 60 in the direction toward the upper part of the mold 70 in the state before extraction, that is, the extraction direction, that is, in conjunction with the direction of the arrow 40a. In addition, the state before extraction means the state from when the compact is molded to before the compact is extracted.

The spray nozzle 19 of the spray coating device 10 located in front of the feeder 40 is positioned above the mold 70. The spray coating device 10 is used to form the signal to open the solenoid valve of the air supply path 21 from the compressed powder. Device reception. When the solenoid valve of the air supply path 21 is opened, air flows into the air supply path 21 and the air branch path 22 in FIG. 1, the needle roller 15 is pushed up, and a gap is formed in the needle roller receiving portion 16. As a result, the spray coating device 10 can spray the mold lubricant on the mold 70. Through this process, an oil film 80 of mold lubricant is formed on the inner wall surface of the mold 70.

When the spray nozzle 19 of the spray coating device 10 is not positioned above the mold 70, a signal to close the solenoid valve of the air supply path 21 is received from the compact molding device. When the solenoid valve of the air supply path 21 is closed, the needle roller 15 and the needle roller receiving portion 16 are brought into contact by the elastic force of the spring 13 in FIG. 1 to stop the supply of mold lubricant. As a result, the spraying of the mold lubricant oil generated by the spray coating device 10 is stopped.

The method of controlling the time when the mold lubricant is sprayed from the spray coating device 10 is as described above. For example, it can be sprayed at a predetermined time by a sensor that senses that a predetermined part of the feeder 40 or the like is present at a predetermined position. method. Furthermore, in addition to the above-mentioned method, a method of spraying each predetermined time according to the reciprocating time when the feeder 40 slides forward and backward may be exemplified.

[Process B] (Filling mechanism)

By forming the frame of the outer wall 41 of the feeder 40, the metal powder 50 is conveyed to the upper part of the mold 70. Since the ground surface side of the feeder 40 is open to form the drop portion of the metal powder 50, a part of the metal powder 50 in the interior of the feeder 40 falls in the direction of the arrow 50b and is filled in the mold 70.

[Process C] (Wiping and cutting mechanism)

The feeder 40 is slid in the direction of the arrow 40c on the substantially flat mold plate 60. At this time, the scraping portion 42 formed in front of the frame portion of the outer wall 41 is scraped above the metal powder 50 filled in the mold 70 and along the upper surface of the substantially flat mold plate 60.

[Process D] (Forming mechanism)

The metal powder 50 filled in the mold 70 is formed by the upper punch 91 that moves from the upper direction of the mold 70 in the direction of the arrow 91d, and the lower punch 92 that moves from the lower direction of the mold 70 in the direction of the arrow 92d. It is pressed to form a pressed powder body 51.

[Process E] (Pull out mechanism)

After the compact 51 is formed, the upper punch 91 moves in the direction of the arrow 91e. The lower punch 92 moves in the direction of the arrow 92e until the upper surface of the lower punch 92 is positioned on the upper surface of the die plate 60 to move the powder compact 51 to the upper surface of the die plate 60.

(Extraction agency)

The feeder 40 slides in the direction of arrow 40e again. By the extraction part 43 provided in front of the sliding feeder 40, the compressed powder body 51 is extracted in the direction of arrow 51e.

After the above-mentioned process E, the process A is performed again, and the mold lubricant is sprayed on the mold 70 from the spray coating device 10 again.

As in the above-mentioned feeder 40, in the process A to the process E, by alternately reciprocating and coating the mold lubricating oil on the mold repeatedly, the molded powder can be extracted sequentially.

The cycle of process A to process E can be about 6 seconds per cycle. Therefore, by using the mold lubricant, spray coating device, and powder compact molding device of the present invention, it is possible to perform high-speed: spray coating of mold lubricant, filling of metal powder into the mold, and compaction of powder Extraction of forming and pressing powder.

<Production of Sintered Body>

The powder compact produced as described above can be sintered by sintering a large number of them side by side in a furnace. In the production of sintered bodies, over The cycle of process A to process E, that is, the process of spray coating of mold lubricating oil, filling of metal powder into the mold, molding of the compact, and extraction of the compact is a rate control process. Therefore, by speeding up the above process, the production of sintered bodies can be speeded up.

Also, the cycle of process A to process E can be the opposite of about 6 seconds per cycle. This cycle is only delayed by 1 to 3 seconds, and the cycle will increase by 16-50%. In addition, in the cycle of process A to process E, if problems such as wear occur, the production of compacts cannot be continued, which will cause major obstacles to the production of sintered bodies.

Therefore, the period of the process A to the process E should not cause a delay of several seconds, and the occurrence of the problem can be suppressed as much as possible.

In the cycle of process A to process E, for example, if powdered mold lubricant is used, or mold lubricant with uneven oil film is used, or a solvent that is not easy to evaporate is used for mold lubricant, the cycle will be longer and wear. The problem will occur, and the production efficiency of the sintered body tends to drop significantly.

And the time lag between the spray coating of the mold lubricant and the filling of the metal powder into the mold, the time lag between the filling of the metal powder into the mold and the forming of the compact, or the forming and compaction of the compact If the time lag between the extraction of the powder becomes larger, the cycle becomes longer, and the production efficiency of the sintered body tends to decrease drastically.

Mold lubricant can reduce the friction between mold and metal powder. Therefore, the blending amount of the mixed lubricant can be reduced, and the Compressibility of pressed powder. From the viewpoint of the lubricity between metal powders, the blending amount of the mixed lubricant of the metal powders is preferably 0.05% by mass or more, and more preferably 0.1 or more. In addition, the blending amount of the mixed lubricant of the metal powder is preferably 0.6% by mass or less, more preferably 0.5% by mass or less, more preferably 0.4% by mass or less, and particularly preferably 0.3% by mass or less. If the mixed lubricant blended with the metal powder is less than 0.05% by mass, the apparent density of the mixed lubricant blended with the metal powder tends to decrease. In addition, since it is difficult to optimally rearrange the metal powder from the filling stage to the initial stage of compression, there is a tendency that the density of the compact cannot increase. That is, the friction between the particles of the metal powder increases, the fluidity of the metal powder deteriorates, and the compressibility of the compact tends to decrease. In addition, if the amount of the mixed lubricant blended with the metal powder exceeds 0.6% by mass, the mixed lubricant tends to hinder compression and make it difficult to increase the density of the compact. That is, the mixed lubricant remains in the metal powder, and it tends to be difficult to improve the compressibility of the compact.

The type of mixed lubricant is not particularly limited. For example, metal bases such as zinc stearate and lithium stearate, amide stearate, bisamide stearate, and ethylene bisstearamide can be cited. The amide-based lubricants.

For the mold lubricant of the present invention, by using a mold lubricant that is easy to dry and can uniformly form an oil film by applying a small amount of coating, the lubricity between the mold and the metal powder can be maintained, and the effect of preventing wear is also improve. Therefore, the amount of the mixed lubricant mixed with the metal powder can be reduced by about 75%. As a result, the fluidity of the metal powder can be maintained when the metal powder is filled in the mold during the molding of the compact. Moreover, because the compact is compact, it has a tendency to increase the density of the compact. to. Furthermore, since the voids generated by the removal of the mixed lubricant during sintering can be minimized, the density of the final sintered body can be improved.

A high-density sintered body has excellent physical properties in terms of rotational bending fatigue strength, compression ring strength, dimensional accuracy, tensile strength, hardness, or wear resistance.

Therefore, the high-density sintered body can be optimally used for, for example, gears and clutch parts of deceleration mechanisms used in electric tools, and electromagnetic materials that are mostly used in the fields of automobiles and home appliances.

[Example]

Hereinafter, using Examples and Comparative Examples, the mold lubricant of the present invention will be described in detail. In addition, the present invention is not limited to the following embodiments, and the constituent elements can be modified and embodied without departing from the essence of the present invention. In addition, various inventions can be formed by appropriately combining plural constituent elements in the embodiments. Some constituent elements may be deleted from all constituent elements shown in the embodiment. Furthermore, the constituent elements of different embodiments may be combined as appropriate.

(Example 1) <Production of mold lubricants>

By mixing: solvent G (manufactured by Exxon Mobil Corporation, Isoper-G; isoparaffin mixture with 9 to 12 carbon atoms) as a hydrocarbon solvent 90% by mass, and oiliness improver A (manufactured by Shin-Etsu Chemical Co., Ltd.) , X22- 1877; modified silicon) 10% by mass, then mold lubricant can be obtained.

(Examples 2 to 4 and Comparative Examples 1 to 5)

From the composition shown in Table 3, except for blending a hydrocarbon solvent, an oiliness improver, or an extreme pressure agent, a mold lubricant was produced in the same manner as in Example 1. In addition, the hydrocarbon solvents, oiliness improvers, and extreme pressure agents used are as shown in Table 1 or 2.

<Measurement of dynamic viscosity of mold lubricant>

The mold lubricating oil obtained in the examples or comparative examples was poured into a Ubbelohde viscometer (manufactured by Yoshida Scientific Instruments Co., Ltd., U-1B-255) in a predetermined amount, and was allowed to stand vertically in a constant temperature bath maintained at 40°C It took 10 minutes. The time (seconds) for the meniscus of the lubricating oil (the bend of the liquid surface) to pass from the time mark E to F is measured by the stopwatch, and the measured value (seconds) and the Ubbelohde used The viscometer constant (unique value) of the viscometer is multiplied to calculate the dynamic viscosity of the mold lubricant. The measurement results of the dynamic viscosity of the mold lubricant are shown in Table 3.

<Measurement of break time of mold lubricant>

0.03 g of the mold lubricant obtained in the examples or comparative examples was coated on a test piece (SPCC), and the test was performed using a friction and abrasion tester. The friction and abrasion tester, that is, the friction generator, used FPR-2100 manufactured by RHESCA Co., Ltd. In addition, in order to measure the coefficient of friction on the test piece, a press was made at a reciprocating speed of 42.9 cpm, a reciprocating width of 35 mm, and SUJ-2. The time required for the coefficient of friction to exceed 0.8 was regarded as fracture under the conditions of a temperature of 50°C and a load of 3000 g. Time, the break time of the mold lubricant was measured. The measurement results of the breaking time are shown in Table 3.

<Measurement of average dynamic friction coefficient of mold lubricant>

0.03 g of the mold lubricant obtained in the examples or comparative examples was coated on a test piece (SPCC), and the test was performed using a friction and abrasion tester. The friction and wear tester is also the friction generator, which uses RHESCA FPR-2100 manufactured by a company limited by shares. In addition, in order to measure the friction against the test piece, a press was made in SUJ-2 under the conditions of a temperature of 100°C and a load of 3000 g, and a linear reciprocating motion with a reciprocating width of 35 mm and a reciprocating speed of 42.9 cpm was performed. The average value of the dynamic friction coefficient when the indenter reciprocates 20 times is the average dynamic friction coefficient. In addition, the stop condition is that the time required to reciprocate the pressure 20 times is a condition of 20 seconds. The measurement results of the average dynamic friction coefficient are shown in Table 3.

<Evaluation of the lubricity of mold lubricants>

The lubricity of mold lubricants was evaluated in three stages based on the following criteria in the order of "excellent", "good", and "not possible". Table 3 shows the evaluation results of the lubricity of the mold lubricant.

Excellent: Break time is more than 150 seconds

Good: Break time is more than 50 seconds but less than 150 seconds

Not possible: the breaking time is less than 50 seconds or the measurement is not possible

<Evaluation of the safety of mold lubricants>

The safety of mold lubricants was evaluated in three stages based on the following criteria in the order of "excellent", "good", and "not possible" considering the ignitability of the solvent. Table 3 shows the evaluation results of the safety of the mold lubricant. In addition, the main component means the one with the highest content ratio among the constituent components.

Excellent: The ignition point of the main component is above 95℃

Good: The ignition point of the main component is more than 30℃ and less than 95℃

Not possible: the ignition point of the main component is below 30°C

The mold lubricants obtained in Examples 1 to 4 have long fracture time, low average dynamic friction coefficient, and good lubrication performance. In addition, the dynamic viscosity is also the best, and it is the best mold lubricant for micro-coating produced by spray.

In the mold lubricant obtained in Comparative Example 1, the solvent E dries quickly, and the formation of the lubricating film is advanced, so the lubricity is evaluated as "excellent". However, because the ignition point of solvent E is -24°C, and mold lubricants are easily ignited and dangerous, the safety evaluation is "not possible".

The mold lubricating oil obtained in Comparative Example 2 is when it breaks Time is shortened, and the average dynamic friction coefficient is high, the lubrication performance is poor. The mold lubricating oil obtained in Comparative Example 4 had low drying properties and could not form a uniform oil film. The mold lubricating oil obtained in Comparative Example 3 or 5 had a high dynamic viscosity and could not be applied in a small amount by spray.

(Production example 1~4) <Mixed metal powder and mixed lubricant>

In the Fe-Ni-Cu-Mo system, about 99 parts of gold powder were expanded and fitted with about 99 parts of carbon powder and about 1 part of metal powder was added. The commercially available zinc stearate as a mixed lubricant was used as shown in Table 4. Ratio mixing to produce metal powder mixed with mixed lubricant. In addition, the Fe-Ni-Cu-Mo-based partially expanded gold powder used in this production example is a powdery mixture containing iron as the main component. The mixture contains 1 to 5 wt% nickel and copper 1 ~3% by weight, 0.1 to 1.0% by weight of molybdenum, and 0.2 to 1.5% by weight of carbon.

<Measurement of fluidity of metal powder>

The fluidity of the metal powders obtained in Production Examples 1 to 4 was measured in accordance with JIS Z2502. The measurement results of fluidity are shown in Table 5.

<Measurement of the apparent density of metal powder>

The appearance density of the metal powders obtained in Production Examples 1 to 4 was measured in accordance with JIS Z2504. The measurement results of the appearance density are shown in Table 5.

When judging the sum of fluidity and appearance density, the blending amount of the mixed lubricant is preferably 0.6% by mass or less. However, when the blending amount of the mixed lubricant is 0% by mass, the apparent density becomes low, and the density of the compact may not easily increase. Therefore, 0.05 to 0.6% by mass of the lubricant is preferably blended with the metal powder. Furthermore, it is more preferable to blend the mixed lubricant with 0.1 to 0.6% by mass to the metal powder, and it is more preferable to blend the mixed lubricant with 0.1 to 0.4% by mass.

<Powder molding>

The mold lubricating oil obtained in Example 1 was spray-coated with 0.1 ml on a mold having a diameter of 16 cm and a depth of 30 cm using the spray coating device shown in Figure 1. The gun distance from the tip of the nozzle of the spray coating device to the mold is 3 mm.

Furthermore, in the above-mentioned spray coating device, six air supply holes are provided around the oil supply hole. The air supply hole and the oil supply hole are arranged at positions twisted with each other, and the angle formed by the air supply hole and the oil supply hole measured from a direction perpendicular to a substantially plane including one air supply hole is 30 degrees. That is, when the air supply hole and the oil supply hole are viewed from the position where the air supply path side end of one air supply hole overlaps the oil supply hole, the angle formed by the air supply hole and the oil supply hole is It becomes 30 degrees. Moreover, in the fitting part of the needle bearing hole and the needle tip, the diameter of the needle bearing hole is 0.65mm, the diameter of the needle tip is 0.8mm, the diameter of the needle bearing hole and the tip of the needle The difference in diameter is 0.075mm. The angle formed by the approximately truncated cone-shaped inclined part of the needle roller inclined part is 25 degrees, and the angle formed by the approximately cone-shaped inclined part of the needle receiving part is for the approximate cone of the needle inclined part The angle formed by the terrace-shaped inclined portion is -2 degrees.

Using the powder compact molding device shown in Fig. 3, the metal powder obtained in Production Example 1 was filled into the mold, and the powder compact was molded at 40°C. The load pressure during the molding of the compact is 1000 MPa.

The time required from the spraying of the mold lubricant to the extraction of the compressed powder, that is, the cycle is 6 seconds on average.

<Measurement of the compressibility of powder compact>

The compressibility of the pressed powder was measured according to JPMA P09 (Japan Powder Metallurgy Industry Association Standard). Table 6 shows the measurement results of the compressibility of the powder compact.

<Measurement of press load at the beginning of extrusion>

The punching load at the start of extrusion is measured by measuring the pressure when the lower punch of the powder compact forming device in Fig. 3 pushes the powder. Table 6 shows the measurement results of the punching load at the beginning of extrusion.

<Measurement of extraction pressure of compressed powder>

The extraction pressure of the pressed powder was measured according to JPMA P13 (Japan Powder Metallurgy Association Standards). The measurement results of the extraction pressure of the pressed powder are shown in Table 6.

(Examples 5~8)

In the composition shown in Table 6, a mold lubricant was produced in the same manner as in Example 1, except that a hydrocarbon solvent, an oiliness improver, or an extreme pressure agent were blended. The hydrocarbon solvents, oiliness improvers, and extreme pressure agents used in the production of mold lubricants are as shown in Table 1 or 2. In addition, the powder compact was molded by the same method as in Example 1, and various physical properties were evaluated. Table 6 shows the composition of the mold lubricants obtained in Examples 5 to 8 and the evaluation results of various physical properties.

Compared with Example 1 where the extreme pressure agent A is not blended, in Example 5 where the extreme pressure agent A is blended by 0.1% by mass, the compressibility and extraction pressure of the powder compact are the same as those of Example 1. However, in Example 6 in which the extreme pressure agent A was blended with 0.5% by mass, the extraction pressure was lower than that in Examples 1 and 5.

Compared with Example 5 in which only solvent G was used as the solvent, in Example 7 in which solvent G and solvent I were used in equal amounts each time, the extraction pressure became higher. Compared with Example 5 in which only solvent G was used as the solvent, in Example 8 in which only solvent I was used, the extraction pressure was also higher.

The following shows a reference example of a case where a powder compact is molded under various conditions with or without using the mold lubricant obtained in Example 1.

(Reference example 1)

Set the load pressure during the molding of the compact to 400MPa, without coating Except for the mold lubricant, the powder compact was formed by the same method as in Example 1.

(Reference example 2)

The mold lubricating oil obtained in Example 1 was formed by the same method as in Reference Example 1, except that 0.1 ml of the mold lubricant was applied to the mold by the same method as in Example 1.

(Reference example 3)

Instead of using the metal powder obtained in Production Example 1, the metal powder obtained in Production Example 2 was used. The compact was formed by the same method as in Reference Example 1.

(Reference example 4)

Instead of using the metal powder obtained in Production Example 1, the metal powder obtained in Production Example 2 was used. The compact was formed by the same method as in Reference Example 2.

(Reference example 5)

When the load pressure during the molding of the powder compact was set to other than 600 MPa, the compact was molded by the same method as in Reference Example 3.

(Reference example 6)

Set the load pressure during the molding of the powder compact to other than 600 MPa. The compact was formed by the same method as in Reference Example 4.

The compressibility of the powder compacts obtained in Reference Examples 1 to 6 and the extraction pressure at the time of molding the powder compacts were measured by the same method as in Example 1. Table 7 shows the measurement results of compressibility and extraction pressure.

Reference Example 1 and Reference Example 2 set the blending amount of the mixed lubricant to 0% by mass. When the load pressure is 400 MPa, compare the compressibility and compression properties when the mold lubricant is coated and uncoated Extract pressure. Reference Example compressibility uncoated die lubricant 1 (6.26g / cm ³⁾ as compared to the coating of Reference Example 2 compression mold lubricant (6.42g / cm ³⁾ is increased. In addition, compared with the extraction pressure (31.56 MPa) of Reference Example 1 where the mold lubricant was not applied, the extraction pressure (16.46 MPa) of Reference Example 2 where the mold lubricant was applied was significantly lower.

In Reference Example 3 and Reference Example 4, the blending amount of the mixed lubricant is set to 0.2% by mass. When the load pressure is 400 MPa, compare the compressibility and compressibility when the mold lubricant is coated and when it is not coated. Extract pressure. Compared with the compressibility (6.49 g/cm ³ ) of Reference Example 3 where the mold lubricant is not applied, the compressibility (6.54 g/cm ³ ) of Reference Example 4 where the mold lubricant is applied is higher. In addition, compared with the extraction pressure (16.39 MPa) of Reference Example 3 where the mold lubricant is not applied, the extraction pressure (14.16 MPa) of Reference Example 4 where the mold lubricant is applied is lower.

In Reference Example 5 and Reference Example 6, the blending amount of the mixed lubricant is set to 0.2% by mass. When the load pressure is 600 MPa, compare the compressibility and the compressibility when the mold lubricant is coated and uncoated Extract pressure. Compared with the compressibility (6.93 g/cm ³ ) of Reference Example 5 where the mold lubricant is not coated, the compressibility (7.0 g/cm ³ ) of Reference Example 6 coated with the mold lubricant is higher. In addition, compared with the extraction pressure (32.08 MPa) of Reference Example 5 where the mold lubricant is not applied, the extraction pressure (27.17 MPa) of Reference Example 6 where the mold lubricant is applied is lower.

As described above, when the mold lubricant is applied, the compressibility becomes high, and the extraction pressure decreases, and good results can be obtained.

(Reference example 7)

The load pressure during the molding of the compact was set to other than 800 MPa, and the compact was formed by the same method as in Reference Example 5. However, since the mold lubricant was not applied, abrasion occurred and the compact was not high. Densification.

(Reference example 8)

When the load pressure during the molding of the powder compact was set to other than 800 MPa, the compact was molded by the same method as in Reference Example 6.

(Reference example 9)

When the load pressure during the molding of the powder compact was set to other than 1000 MPa, the compact was molded by the same method as in Reference Example 6.

(Reference example 10)

When the load pressure during the molding of the powder compact was set to other than 1200 MPa, the compact was molded by the same method as in Reference Example 6.

The compressibility of the powder compacts obtained in Reference Examples 7 to 10 and the extraction pressure at the time of molding the powder compacts were measured by the same method as in Reference Example 1. The measurement results of compressibility and extraction pressure are shown in Table 8.

Such as Reference Example 7 where the mold lubricant is not coated, the load pressure becomes At 800 MPa, wear has already occurred. On the other hand, in Reference Examples 8 to 10 coated with mold lubricant, as the load pressure becomes higher, the compressibility becomes higher, and the powder compact can be molded without wear or the like.

In particular, in Reference Example 10 with a load pressure of 1200 MPa, even if the molding was continuously performed 200 times, no abrasion occurred, and the compressibility could be improved to 7.5 g/cm ³ .

(Reference example 11)

The amount of the mixed lubricant blended in the metal powder was set to 0.5% by mass, and the compactness was formed by the same method as in Reference Example 7 except that the compressibility was 7.2 g/cm ³ or more under the load pressure .

(Reference example 12)

The amount of the mixed lubricant blended into the metal powder was set to 0.5% by mass, and the compactness was formed by the same method as in Reference Example 8, except that the compressibility was 7.2 g/cm ³ or more under the load pressure. .

The compressibility of the powder compacts obtained in Reference Examples 11 and 12 and the extraction pressure at the time of molding the powder compacts were measured by the same method as in Reference Example 1. The measurement results of compressibility and extraction pressure are shown in Table 9.

The density of Reference Example 11 and Reference Example 12 was a load pressure of 7.2 or more. In Reference Example 11 where the mold was not coated and Reference Example 12 where the mold was coated, no significant difference occurred. On the other hand, compared with the extraction pressure (27 MPa) of Reference Example 11 where the mold was not coated, the extraction pressure (17 MPa) of Reference Example 12 coated with mold lubricant was reduced. From this, it can be confirmed that the extraction pressure can be reduced by applying mold lubricant.

<Production of Sintered Body> (Reference example 13)

The compact obtained in Reference Example 4 was sintered at 1100°C for 30 minutes in a reducing atmosphere to obtain a sintered body.

<Measurement of Density of Sintered Body>

The density of the obtained sintered body was measured in accordance with JIS Z 2501. The density measurement results are shown in Table 10.

<Measurement of Strength of Sintered Compact Ring>

The compression ring strength of the obtained sintered compact was measured in accordance with JIS Z 2507. The measurement results of the compression ring strength are shown in Table 10.

<Measurement of gas amount during sintering>

The amount of gas generated during sintering was measured in an intensified manner using Vocalmass (trade name) manufactured by Japan Metal Chemical Corporation. The estimated value of the gas amount is shown in Table 10.

(Reference example 14)

Except for the powder compact obtained in Reference Example 6, the powder compact was formed by the same method as in Reference Example 13. And, the obtained compact was sintered by the same method as in Reference Example 13 to obtain a sintered body.

(Reference example 15)

Except for using the powder compact obtained in Reference Example 8, the compact was formed by the same method as in Reference Example 13. And, the obtained compact was sintered by the same method as in Reference Example 13 to obtain a sintered body.

(Reference example 16)

Except for using the powder compact obtained in Reference Example 9, the compact was formed by the same method as in Reference Example 13. And, the obtained compact was sintered by the same method as in Reference Example 13 to obtain a sintered body.

(Reference example 17)

Instead of using the metal powder obtained in Production Example 1, the metal powder obtained in Production Example 4 was used. The compact was formed by the same method as in Reference Example 13. And, the obtained compact was sintered by the same method as in Reference Example 13 to obtain a sintered body.

(Reference example 18)

Instead of using the metal powder obtained in Production Example 1, but using the metal powder obtained in Production Example 4, the compact was formed by the same method as in Reference Example 14. And, the obtained compact was sintered by the same method as in Reference Example 14 to obtain a sintered body.

(Reference Example 19)

Instead of using the metal powder obtained in Production Example 1, but using the metal powder obtained in Production Example 4, the compact was formed in the same manner as in Reference Example 15. And, the obtained compact was sintered by the same method as in Reference Example 15 to obtain a sintered body.

(Reference example 20)

Instead of using the metal powder obtained in Production Example 1, the metal powder obtained in Production Example 4 was used. The compact was formed by the same method as in Reference Example 16. And, the obtained compact was sintered by the same method as in Reference Example 16 to obtain a sintered body.

The density of the sintered body obtained from Reference Examples 14 to 20, The pressure ring strength and the estimated gas volume were measured by the same method as in Reference Example 13. Table 10 shows the measurement results of the sintered body density, compression ring strength, and estimated gas amount obtained in Reference Examples 14-20.

Claims (5)

A method for forming a powder compact, which is characterized by having: a coating process of coating a mold lubricant by a spray coating device; a filling process of filling the mold coated with the mold lubricant with metal powder; The forming process of pressing the metal powder to form a compact; and the drawing process of pulling the formed compact to an upper part of the mold. The mold lubricant contains: 50~98% by mass of carbon Hydrocarbon solvents with the number 7 to 18 and oil modifiers greater than 0% to 20% by mass or extreme pressure agents greater than 0% to 20% by mass. For example, the powder compact molding method of the first item of the patent application, wherein the aforementioned hydrocarbon solvent is selected from paraffin-based hydrocarbon solvents, olefin-based hydrocarbon solvents, naphthenic hydrocarbon solvents, and aromatic hydrocarbon solvents One or more kinds of solvents selected from the constituent group. For the compact molding method of item 1 or 2, wherein the oiliness improver is one or more compounds selected from the group consisting of silicon, animal and vegetable fats and oils, and higher fatty acid esters . For example, the powder compact forming method of item 1 or 2 of the scope of patent application, wherein the aforementioned extreme pressure agent is made of phosphate ester, sulfide vulcanized oil, dithio One or more compounds selected from the group consisting of molybdenum carbamate, zinc dialkyldithioate, and molybdenum dithiophosphate. For example, the powder compact forming method of item 1 or 2 of the scope of the patent application further includes: an extraction process of extracting the drawn powder compact from the upper part of the mold by an extraction means, the extraction means and the spray coating The cloth device is the one that moves in conjunction with the direction toward the upper part of the mold, that is, the extraction direction in the state before extraction. The extraction means is arranged in the extraction direction in front of the spray coating device, by The extraction means and the spray coating device are moved in the extraction direction, so that the extraction means extracts the compressed powder through the upper part of the mold, and when the spray coating device reaches the upper part of the mold, the mold lubricant is applied to The aforementioned mold.

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