CN116652175A - A feed composition formula for metal powder injection molding and its part preparation method - Google Patents

Abstract

The invention provides a feeding component formula for metal powder injection molding and a method for preparing parts thereof, which belong to the technical field of powder metallurgy injection molding. The feeding component formula for metal powder injection molding includes metal powder, binder and lubricant. Part, the mass percentage of metal powder, binder and lubricant in the feed is 84.5‑95.5%, 3.5‑13.5% and 1.0‑2.0%, respectively, and the metal powder element is calculated by mass fraction, which is different from the traditional slider Compared with carbon steel for machining and manufacturing, metal powder injection molding technology is used to optimize and define the feeding formula and optimize the key parameters in the process chain. The micro guide rail sliders produced have high strength, high toughness and high wear resistance As well as corrosion resistance, by adjusting the formula and adjusting the parameters of the sintering process, the final sintered compact is stable in deformation and within the allowable tolerance range, ensuring the accuracy of the product.

Description

A feed composition formula for metal powder injection molding and its part preparation method

technical field

The invention belongs to the technical field of powder metallurgy injection molding, and in particular relates to a feed component formula for metal powder injection molding and a method for preparing parts thereof.

Background technique

Metal powder injection molding technology (MIM) is a new type of near-net shape technology for parts and components formed by combining polymer chemistry, powder metallurgy technology, metal materials and other disciplines. Its basic process is: first, the metal The powder is uniformly mixed with an organic binder, molded by an injection molding machine, and then the binder in the molded body is removed, and then sintered and densified to obtain the final product. Because it is suitable for mass production of small and complex parts with good mechanical properties and high dimensional accuracy (IT7-IT6), it is known as "the most popular component forming technology today".

Compared with traditional mechanical processing and precision casting, powder metallurgy injection molding has a more uniform internal structure of the product; compared with traditional powder metallurgy pressing/sintering, the product performance is better, the product has high dimensional accuracy and surface finish, and no reprocessing is required Or just a small amount of finishing;

In the prior art, miniature guideway sliders are mainly used in miniature guideways on miniaturized equipment, requiring high matching precision between the slider and the slideway, and requiring the slider to have high strength and high rigidity, which is more capable of bearing a certain load To resist deformation, the surface of the slider is required to be as smooth as possible, and the contact surface with the slide rail has a low friction coefficient, while the traditional guide rail slider is mostly produced by carbon steel by machining. With the industry's miniaturization of products, The requirement for high density is getting higher and higher, and it can no longer meet the requirements. It is urgent to adopt a newer process to improve the original material formula of the product, and strive to produce high-quality sliders.

Contents of the invention

The object of the present invention is to produce a high-performance slider with high strength, high rigidity, high precision and low frictional resistance, and proposes a formula of feeding components for metal powder injection molding and a method for preparing parts thereof.

In order to achieve the above object, the present invention provides the following technical scheme: the mass percentages of the metal powder, the binder and the lubricant in the feed are respectively 84.5-95.5%, 3.5-13.5% and 1.0- 2.0%, the metal powder elements include 16-18% Cr, ≤0.60% Ni, 1.0-2.0% Nb, ≤1.0% Mn, ≤1.0% Si, 0.9- 1.0% of C, ≤0.3% of S, ≤0.75% of Mo, and Fe as balance elements, the sum of the above combination percentages is 100%.

As a preferred solution of the present invention, the metal powder is produced by atomizing molten 440C stainless steel with inert gas.

As a preferred solution of the present invention, in order to make the feed material have better fluidity in the mold cavity and completely fill the mold cavity, the shape of the metal powder is spherical.

As a preferred solution of the present invention, if the particle size of the metal powder is too large, a large number of voids will be generated inside the green body during the subsequent degreasing process, which will reduce the strength of the green body and cause large deformation during the sintering process. If the metal powder particles If the diameter is too small, the binder inside the green body is not easy to come out during the subsequent degreasing process, and the particle diameter of the metal powder is 10-20 microns.

As a preferred solution of the present invention, the binder and lubricant include 50% polyoxymethylene, 33% polyacetylene, 16% polyethylene, and 1% stearic acid in terms of mass percentage.

A preparation method for feeding material for metal powder injection molding, comprising the steps of:

S1. Weigh a certain amount of metal powder according to the formula and add it to the mixer for stirring and heating;

S2. Add the binder and lubricant according to the proportion, and knead to obtain a suitable and uniform feeding material;

S3. Making the feed material into pellets of a certain shape suitable for injection molding in a granulator.

As a preferred solution of the present invention, in step S1, the metal powder is preheated to 150-200° C. in advance.

As a preferred solution of the present invention, in step S2, the kneader speed is set to 15-35r/min, the kneading temperature is set to 170-200°C, and the kneader is uniformly stirred for 60-120min.

As a preferred solution of the present invention, in step S2, the melt index of the obtained feed material is 1000-1500g/10min.

As a preferred solution of the present invention, in step S3, the particles suitable for injection molding are short and thin rod-shaped particles.

A kind of metal powder injection molding feed material prepares the method for miniature guide rail slider, comprises the following steps:

S1. Put the prepared feed into the silo of the injection molding machine. The feed is completely plasticized in the injection barrel by the heat of the external heater and screw mechanization. , cooling, and demoulding to obtain a molded blank;

S2. Use the oxalic acid catalytic degreasing furnace to catalyze degreasing, put the molded billet on the hopper in the furnace, adjust the degreasing temperature to 110±5°C, and under the action of the fan, the oxalic acid is blown into the furnace cavity under the nitrogen gas, and the billet body The binder decomposes into formaldehyde, burns to generate carbon dioxide and water, and the tail gas is greenly discharged;

S3. Put the degreased body into a vacuum sintering furnace, feed nitrogen gas, adjust the temperature in the furnace, degrease through negative pressure, and remove a small amount of binder remaining inside the body after catalytic degreasing;

S4. Extract the nitrogen in the furnace, increase the temperature, and sinter in vacuum to form a sintering neck between the atoms inside the green body, and the green body is densified;

S5. Further increase the temperature in the furnace, feed argon gas, increase the pressure in the furnace, and through partial pressure sintering, the atoms of the green body are further densified, and finally fully densified.

As a preferred solution of the present invention, in step S2, the degreased green body should not be placed outside for a long time, because the green body easily absorbs moisture in the air, which will oxidize the degreasing parts, resulting in abnormal degreasing and affecting the judgment of degreasing rate .

Compared with prior art, the beneficial effect of the present invention is:

1. In the present invention, the metal powder injection molding technology is used to optimize and define the feeding formula, optimize the key parameters in the process chain, and the micro-rail sliders obtained have high strength, high toughness, high wear resistance, and corrosion resistance , by adjusting the formula and adjusting the parameters of the sintering process, the final sintered billet is stable in deformation, and the accuracy of the product is guaranteed within the allowable tolerance range.

2. In the present invention, the green body after degreasing should not be placed outside for a long time, so as to avoid the oxidation of the degreasing parts due to the easy absorption of moisture in the air by the green body, resulting in abnormal degreasing and affecting the judgment of degreasing rate.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the attached picture:

Fig. 1 is the perspective view of kneader among the present invention;

Fig. 2 is the perspective view of stirring assembly among the present invention;

Fig. 3 is the front view of kneader among the present invention;

Fig. 4 is the side view of kneader among the present invention;

Fig. 5 is the first sectional view of kneader among the present invention;

Fig. 6 is the second sectional view of kneader among the present invention;

Fig. 7 is the preparation flow diagram of feeding material for metal powder injection molding in the present invention;

Fig. 8 is the process block diagram of the preparation of miniature rail slide block by metal powder injection molding feeding material in the present invention;

Fig. 9 is an actual picture of the molded embryo obtained by injection in the present invention.

In the figure: 1, bottom plate; 101, pole; 102, top plate; 2, slide rail; 201, first electric push rod; 202, first slider; 203, second electric push rod; 204, second slider ;3, mixing box; 301, heating unloading plate; 302, fixed rod; 303, first fixed plate; 304, second fixed plate; 305, third electric push rod; 306, first motor; 4, top Cover; 401, connecting plate; 402, turntable; 403, L-shaped frame; 404, second motor; 405, rotating rod; 406, first gear; 407, second gear; 408, mounting frame; 409, third motor ; 410, stirring blade.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

Referring to Fig. 1-Fig. 9, the present invention provides the following technical solutions:

Step 1: The molten SUS440C stainless steel is made into spherical or nearly spherical powder particles through the combined water-gas atomization method;

Step 2: put stainless steel powder accounting for 85% of the total mass into a mixer for stirring, and preheat to 150°C;

Step 3: Put the binder accounting for 13% of the total mass and the stearic acid accounting for 2% of the total mass into the mixer to fully stir and mix with the metal powder, set the speed of the mixer to 15r/min, and the mixing temperature Set at 170°C and stir evenly for 60 minutes;

Step 4: Put the uniform feeding material into the granulator to make small cylindrical granules, and cool them into solid small cylindrical rods;

Step 5: Put the feed obtained by granulation into the hopper of the injection molding machine, set the injection pressure at 9MPa, and raise the temperature to 170°C, 175°C, 180°C, 185°C, and 190°C at a heating rate of 5°C/min. . The feeding material is injected into the gate by the screw through the nozzle in stages in the barrel of the injection machine, and the feeding material fully fills the mold cavity. The mold temperature is set at 120°C, the holding pressure is set at 10MPa, and the holding pressure is 1s;

Step 6: Turn on the water cooling system of the mold to cool the injection billet, and then take out the molded billet from the cavity;

Step 7: Put the molded body into the oxalic acid catalytic degreasing furnace. The oxalic acid is carried by nitrogen, and contacts with the binder in the molded body, and the reaction generates formaldehyde. After the formaldehyde is burned, carbon dioxide and water are emitted, and the molded body is effectively degreased. , the degreasing rate reaches 90%, and the green body is a connected void structure at this time;

Step 8: Put the degreased green body into a vacuum sintering furnace for sintering under a nitrogen protective atmosphere. The green body first goes through the pre-sintering stage, and the sintering temperature is raised from 5°C/min to 360°C for 30 minutes, and then 10°C/min Raise to 480°C for 60 minutes, then raise from 15°C/min to 600°C for 90 minutes, then rise from 20°C/min to 750°C, degrease with negative pressure to remove the remaining binder inside the green body clean;

Step 9: Further raise the temperature at 10°C/min to 1050°C for 1 hour, pump out the nitrogen in the furnace, and vacuum sinter to form a sintering neck between the atoms and densify the green body; then raise the temperature to 1248°C at 15°C/min , enter argon gas, increase the pressure in the furnace to 20KPa, through pressurized calcination, the atoms are bonded more closely, the green body is further densified, and finally fully densified;

Step 10: Cool down to 900°C at 20°C/min, keep warm for 1 hour, and then force-cool to 30°C;

Step 11: Reshape the sintered and cooled slider to obtain the final finished part.

The mixing machine in the step 2 is made up of a frame assembly, a mixing assembly, a stirring assembly and a lifting assembly;

The frame assembly includes a bottom plate 1, a pole 101 and a top plate 102. There are four poles 101. The four poles 101 are respectively fixedly connected to the four corners of the upper end of the bottom plate 1. The top plate 102 is fixedly connected to the upper ends of the four poles 101. ;

The mixing assembly comprises a mixing box 3, a heating discharge plate 301, a fixed rod 302, a first fixed plate 303, a second fixed plate 304 and a third electric push rod 305, the first fixed plate 303, the second fixed plate 304 and There are two third electric push rods 305, four fixed rods 302, the mixing box 3 is arranged on the upper side of the bottom plate 1, the mixing box 3 is connected with the sliding assembly, and the two second fixing plates 304 are fixed Connected to the circumferential surface of the mixing box 3, the two third electric push rods 305 are respectively fixedly connected to the lower ends of the two second fixed plates 304, and the two first fixed plates 303 are respectively fixedly connected to the two third electric push rods 305, the four fixed rods 302 are respectively fixedly connected to the upper ends of the two first fixed plates 303, the heating unloading plate 301 is fixedly connected to the upper ends of the four fixed rods 302, and the heating unloading plate 301 and the mixing box 3 matches;

The stirring assembly includes a top cover 4, a connecting plate 401, a turntable 402, an L-shaped frame 403, a second motor 404, a rotating rod 405, a first gear 406, a second gear 407, a mounting frame 408, a third motor 409 and a stirring blade 410 , there are two connecting plates 401 and L-shaped frame 403, four rotating rods 405, the first gear 406, the second gear 407 and stirring blades 410, the top cover 4 matches the mixing box 3, and the two Each connecting plate 401 is fixedly connected to the upper end of the top cover 4, the two top covers 4 are connected to the lifting assembly, the turntable 402 is rotatably connected in the top cover 4, and the two L-shaped frames 403 are fixedly connected to the upper end of the top cover 4, The second motor 404 is fixedly connected to the adjacent ends of the two L-shaped frames 403, the output end of the second motor 404 is fixedly connected to the upper end of the turntable 402, and the four rotating rods 405 are all rotatably connected in the turntable 402, and the four stirring blades 410 are respectively fixedly connected to the circumferential surfaces of the four rotating rods 405, the four first gears 406 are respectively fixedly connected to the circumferential surfaces of the four rotating rods 405, and the four second gears 407 are respectively connected to the upper end of the turntable 402 through rotating shafts. Each second gear 407 meshes with two adjacent first gears 406 respectively, the mounting frame 408 is fixedly connected to the upper end of the rotating disk 402, the third motor 409 is fixedly connected to the surface of the mounting frame 408, and the output of the third motor 409 The end is fixed with the upper end of one of the rotating rods 405;

The lifting assembly includes two slide rails 2, a first electric push rod 201, a first slide block 202, a second electric push rod 203 and a second slide block 204, and the two slide rails 2 are fixedly connected to the bottom plate 1 and the top plate 102. Close to the end, the two first sliders 202 are respectively fixedly connected to the remote ends of the two connecting plates 401, the two first sliders 202 are respectively slidably connected in the two slide rails 2, and the two first electric push rods 201 are fixedly connected to the lower end of the top plate 102, the extension ends of the two first electric push rods 201 are respectively fixedly connected to the upper ends of the two first sliders 202, and the two second sliders 204 are respectively slidably connected to the two sliders. In the rail 2, the two second electric push rods 203 are fixedly connected to the upper end of the base plate 1, and the extension ends of the two second electric push rods 203 are respectively fixedly connected to the lower ends of the two second sliders 204;

Both side ends of the mixing box 3 are fixedly connected with rotating shafts, and the two rotating shafts are respectively connected in two second sliders 204 in rotation, and one of the second sliders 204 is fixedly connected with a first motor 306, the first motor The output end of 306 is connected with one end of one of the rotating shafts;

The operation process of the mixing machine, firstly, the operation of the third electric push rod 305 is controlled to drive the first fixed plate 303 connected to its output end to move, the first fixed plate 303 drives the fixed rod 302 to move, and the fixed rod 302 drives the heating unloading plate 301 to slide to the lower part of the kneading box 3, then add metal powder, binder and lubricant in the kneading box 3 in sequence, and the first electric push rod 201 in the lifting assembly drives the first The slider 202 moves downward, the first slider 202 drives the connecting plate 401 to move downward, the connecting plate 401 drives the top cover 4 to move downward, and covers the upper surface of the mixing box 3 to control the second motor 404 and the third Motor 409 runs simultaneously, and second motor 404 drives turntable 402 to rotate, and the part that is arranged on the surface of turntable 402 and its inside rotates, and the 3rd motor 409 drives rotation rod 405 to rotate, and rotation rod 405 drives the first gear 406 on its surface to rotate, adjacent The two first gears 406 are connected through the second gear 407, and the four rotating rods 405 rotate at the same time. The rotating rods 405 drive the stirring blade 410 to rotate, and the stirring blade 410 rotates and the rotating disc 402 rotates during the rotation of the mixing box 3. The metal powder, binder and lubricant are mixed and stirred. During the stirring process, the metal powder, binder and lubricant in the mixing box 3 are heated by the heating wire installed inside the heating unloading plate 301, and the mixing is completed. Finally, the first electric push rod 201 runs, which indirectly drives the stirring assembly to move upwards, and then controls the operation of the first motor 306 to drive the rotating shaft to rotate, and the rotating shaft drives the mixing box 3 to rotate to a certain angle, and the mixing box 3 is inclined to facilitate unloading. Control the operation of the third electric push rod 305, indirectly drive the heating unloading plate 301 to move upward in the mixing box 3, push out the raw materials that have been mixed in the mixing box 3, and complete the unloading. After the mixing is completed by using this device The heated unloading plate 301 slides in the mixing box 3 to quickly complete the unloading operation. Compared with the traditional mixing machine, it is convenient to clean the inside of the mixing machine and maintain the equipment more conveniently.

Example 2

Step 1: The molten SUS440C stainless steel is made into spherical or nearly spherical powder particles through the combined water-gas atomization method;

Step 2: put stainless steel powder accounting for 90% of the total mass into a mixer for stirring, and preheat to 170°C;

Step 3: Put 9% of the total mass of the binder and 1% of the total mass of stearic acid into the mixer and fully stir and mix the metal powder, set the speed of the mixer to 25r/min, and the mixing temperature Set at 180°C and stir evenly for 100 minutes;

Step 4: Put the uniform feeding material into the granulator to make small cylindrical granules, and cool them into solid small cylindrical rods;

Step 5: Put the feed obtained from granulation into the hopper of the injection molding machine, set the injection pressure to 11MPa, and raise the temperature to 170°C, 175°C, 180°C, 185°C, and 190°C in sequence at a heating rate of 5°C/min , 195°C, the feeding material is injected into the gate by the screw through the nozzle in stages in the barrel of the injection machine, and the feeding material fully fills the mold cavity, the mold temperature is set at 125°C, the holding pressure is set at 12MPa, and the holding pressure is 2s ;

Step 6: Turn on the water cooling system of the mold to cool the injection billet, and then take out the molded billet from the cavity;

Step 7: Put the molded body into the oxalic acid catalytic degreasing furnace. The oxalic acid is carried by nitrogen, and contacts with the binder in the molded body, and the reaction generates formaldehyde. After the formaldehyde is burned, carbon dioxide and water are emitted, and the molded body is effectively degreased. , the degreasing rate reaches 90%, and the green body is a connected void structure at this time;

Step 8: Put the degreased green body into a vacuum sintering furnace for sintering under a nitrogen protective atmosphere. The green body first goes through the pre-sintering stage, and the sintering temperature is raised from 5°C/min to 350°C for 30 minutes, and then 10°C/min Raise it to 470°C for 60 minutes, then raise it from 15°C/min to 590°C and hold it for 90 minutes, then raise it from 20°C/min to 740°C, and remove the remaining binder inside the green body through negative pressure degreasing clean;

Step 9: Further raise the temperature at 10°C/min to 1040°C for 1 hour, pump out the nitrogen in the furnace, and vacuum sinter to form a sintering neck between the atoms and densify the green body; then raise the temperature to 1238°C at 15°C/min , enter argon gas, increase the pressure in the furnace to 20KPa, through pressurized calcination, the atoms are bonded more closely, the green body is further densified, and finally fully densified;

Step 10: Cool down to 890°C at 20°C/min, keep warm for 1 hour, and then force-cool to 30°C;

Step 11: Reshape the sintered and cooled slider to obtain the final finished part.

Example 3

Step 1: The molten SUS440C stainless steel is made into spherical or nearly spherical powder particles through the combined water-gas atomization method;

Step 2: put stainless steel powder accounting for 95% of the total mass into a mixer for stirring, and preheat to 200°C;

Step 3: put the binder accounting for 4.5% of the total mass and the stearic acid accounting for 0.5% of the total mass into the mixer and fully stir and mix the metal powder, set the speed of the mixer to 35r/min, and the mixing temperature Set at 190°C and stir evenly for 120 minutes;

Step 4: Put the uniform feeding material into the granulator to make small cylindrical granules, and cool them into solid small cylindrical rods;

Step 5: Put the feed obtained by granulation into the hopper of the injection molding machine, set the injection pressure to 12MPa, and raise the temperature to 170°C, 175°C, 180°C, 185°C, and 190°C in sequence at a heating rate of 5°C/min , 195°C, 200°C, the feed material is slowly injected into the gate by the push rod in the barrel of the injection machine, and the feed material fully fills the mold cavity. The mold temperature is set at 130°C, and the holding pressure is set at 13MPa. 3s;

Step 6: Turn on the water cooling system of the mold, cool the forming blank, and then remove the forming blank from the mold;

Step 7: Put the molded body into the oxalic acid catalytic degreasing furnace. Under the nitrogen gas, the oxalic acid comes into contact with the binder in the molded body, and the reaction generates formaldehyde. After the formaldehyde is burned, carbon dioxide and water are emitted, and the injection mold is effectively degreased. , the degreasing rate reaches 90%, and the green body is a connected void structure at this time;

Step 8: Put the degreased green body into a vacuum sintering furnace for sintering under a nitrogen protective atmosphere. The green body first goes through the pre-sintering stage, and the sintering temperature is raised from 5°C/min to 340°C for 30 minutes, and then 10°C/min Raise it to 460°C for 60 minutes, then raise it from 15°C/min to 580°C and hold it for 90 minutes, then raise it from 20°C/min to 730°C, and remove the remaining binder inside the green body through negative pressure degreasing clean;

Step 9: Further raise the temperature to 1030°C at 10°C/min and keep it warm for 1 hour, pump out the nitrogen in the furnace, and vacuum sinter to form a sintering neck between the atoms and densify the green body; then raise the temperature to 1228°C at 15°C/min , enter argon gas, increase the pressure in the furnace to 20KPa, through pressurized calcination, the atoms are bonded more closely, the green body is further densified, and finally fully densified;

Step 10: Cool down to 880°C at 20°C/min, keep warm for 1 hour, and then force-cool to 30°C;

Step 11: Reshape the sintered and cooled slider to obtain the final finished part.

The use process of the present invention: when the present invention is in use, firstly weigh a certain amount of metal powder according to the formula and add it to the mixer for stirring and heating; add binder and lubricant according to the proportion, and carry out mixing to obtain a suitable and uniform viscosity. Consistent feeding; the feed is made into shaped pellets suitable for injection molding in the pelletizer; the prepared feed is fed into the silo of the injection molding machine, and the feed is externally heated in the injection barrel The thermal effect of the machine and screw mechanization is completely plasticized, and the nozzle is injected into the mold cavity through the flow channel, and the molded blank is obtained after pressure maintaining, cooling, and demoulding; the oxalic acid catalytic degreasing furnace is used for catalytic degreasing, and the molded blank is put into the hopper in the furnace First, adjust the degreasing temperature to 110±5°C. Under the action of the fan, oxalic acid is blown into the furnace cavity under the nitrogen gas, and the binder in the green body is decomposed into formaldehyde, which is burned to generate carbon dioxide and water, and the tail gas is discharged greenly; Put the degreased billet into the vacuum sintering furnace, feed nitrogen, adjust the temperature in the furnace, degrease through negative pressure, remove the small amount of binder remaining inside the billet after catalytic degreasing; pump out the nitrogen in the furnace, and raise the temperature , through vacuum internal sintering, a sintering neck is formed between the atoms inside the green body, and the green body is densified; finally, the temperature in the furnace is further increased, argon gas is introduced, and the pressure in the furnace is increased. Through partial pressure sintering, the atoms of the green body are further densified, and finally Full density; by using this scheme, compared with the traditional slider made of carbon steel for machining, the metal powder injection molding technology is used to optimize and define the feeding formula and optimize the key parameters in the process chain. The block has high strength, high toughness, high wear resistance, and corrosion resistance. By adjusting the formula and adjusting the sintering process parameters, the final sintered billet is stable in deformation, and the accuracy of the product is guaranteed within the allowable tolerance range.

Finally, it should be noted that: the above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it still The technical solutions recorded in the foregoing embodiments may be modified, or some technical features thereof may be equivalently replaced. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A feed composition formula for metal powder injection molding, characterized in that, the feed material for metal powder injection molding comprises three parts of metal powder, binder and lubricant, and the metal powder, the binder The mass percentages of the lubricant and the lubricant in the feed are 84.5-95.5%, 3.5-13.5%, and 1.0-2.0%, respectively, and the metal powder elements include 16-18% of Cr, ≤0.60% Ni, 1.0-2.0% Nb, ≤1.0% Mn, ≤1.0% Si, 0.9-1.0% C, ≤0.3% S, ≤0.75% Mo, Fe as balance element , the sum of the above combined percentages is 100%. 2. A feed composition formula for metal powder injection molding according to claim 1, characterized in that: the steel grade corresponding to the metal powder after sintering is JISSUS440C, and the metal powder is made by a water-gas combined atomization method , the shape of the metal powder is spherical, and the particle size of the metal powder is 10-20 microns. 3. a kind of metal powder injection molding according to claim 1 is characterized in that, described binding agent, lubricant comprise 50% polyoxymethylene, 33% polyoxymethylene by mass percent Acetylene, 16% polyethylene, 1% stearic acid. 4. A method for preparing a feed for metal powder injection molding, using a feed component formula for metal powder injection molding according to any one of claims 1-3, characterized in that it comprises the steps of: S1. Weigh a certain amount of metal powder according to the formula and add it to the mixer for stirring and heating; S2. Add the binder and lubricant according to the proportion, and knead to obtain a suitable and uniform feeding material; S3. Making the feed material into pellets of a certain shape suitable for injection molding in a granulator. 5 . The method for preparing feedstock for metal powder injection molding according to claim 4 , characterized in that: in step S1 , the metal powder is preheated to 150-200° C. in advance. 6. A method for preparing feedstock for metal powder injection molding as claimed in claim 4, characterized in that: in step S2, the speed of the mixer is set to 15-35r/min, and the mixing temperature is set to 170 Stir evenly at -200°C for 60-120 minutes, and the melt index of the obtained feed is 1000-1500g/10min. 7. The method for preparing feedstock for metal powder injection molding according to claim 4, characterized in that: in step S3, the particles suitable for injection molding are short and thin rod-shaped particles. 8. A kind of method that metal powder injection molding feeding material prepares miniature rail slide block, has used a kind of metal powder injection molding described in any one of claim 1-3 and is used for feeding component formula, and in claim 4 The preparation method of a feedstock for metal powder injection molding is characterized in that it comprises the following steps: S1. Put the prepared feed into the silo of the injection molding machine. The feed is completely plasticized in the injection barrel by the heat of the external heater and screw mechanization. , cooling, and demoulding to obtain a molded blank; S2. Use the oxalic acid catalytic degreasing furnace to catalyze degreasing, put the molded billet on the hopper in the furnace, adjust the degreasing temperature to 110±5°C, and under the action of the fan, the oxalic acid is blown into the furnace cavity under the nitrogen gas, and the billet body The binder decomposes into formaldehyde, burns to generate carbon dioxide and water, and the tail gas is greenly discharged; S3. Put the degreased body into a vacuum sintering furnace, feed nitrogen gas, adjust the temperature in the furnace, degrease through negative pressure, and remove a small amount of binder remaining inside the body after catalytic degreasing; S4. Extract the nitrogen in the furnace, increase the temperature, and sinter in vacuum to form a sintering neck between the atoms inside the green body, and the green body is densified; S5. Further increase the temperature in the furnace, feed argon gas, increase the pressure in the furnace, and through partial pressure sintering, the atoms of the green body are further densified, and finally fully densified. 9. A method for preparing a miniature guide rail slider by metal powder injection molding feed, characterized in that, in step S2, the green body after degreasing should not be placed outside for a long time, because the green body easily absorbs moisture in the air, which is harmful to degreasing Parts are oxidized, resulting in abnormal degreasing and affecting the judgment of degreasing rate. 10. The preparation method of a feed material for metal powder injection molding according to claim 4, wherein the kneader is composed of a frame assembly, a mixing assembly, a stirring assembly and a lifting assembly, and the frame assembly includes a bottom plate (1), pole (101) and top plate (102), pole (101) is provided with four, and four poles 101 are respectively fixedly connected to the four corners of the upper end of base plate (1), and top plate (102) is fixedly connected to The upper ends of the four poles 101.