SU55528A1 - Method of deposition of a solid layer of soft metals - Google Patents

Description

In order to increase the productivity of metal-cutting machines, various hard alloys are widely used in production: high-speed steels of various grades, alloys “Visible,” Win, ”Stellite, etc. The presence in the composition of these hard alloys of various rare metals as alloying elements causes their high cost and relatively large scarcity.

In order to save the expenditure of deficient ferroalloys in the manufacture of cutting tools, in the practice of metal cutting, composite tools are used, in which the cutting part is a relatively small piece of hard alloy welded or soldered to the rest of the tool (holder), made from cheap conventional steel. Thus, the use of composite cutting tools is the main measure of the practical implementation of the savings of scarce rare metals that are part of hard metals for the manufacture of high-speed tools. The manufacturing methods of composite tools are not very diverse. At present, the following of them are widespread in production practice:

1. Welding high-speed steel plates to holders by the method of resistance electric welding.

2. Welding of plates of fast cutting steel to the holders by the method of electric arc welding.

3. Welding of high-speed steel plates to holders by the method of forge forge welding.

4. Welding of high-speed steel plates to the holders using gas (acetylene-oxygen) welding.

5. Soldering of plates of superhard alloys („Win wins”) with copper to holders from semi-precious steel.

The above methods for their implementation require certain skills, without which manufactured composite tools

they are distinguished by insufficient strength and reliability in operation (rebounding of the plates is observed).

The latter circumstance necessitates the presence of highly qualified welders in production. In addition, most of the above properties are characterized by significant practical difficulties in terms of the scarcity of materials required for work (acetylene oxygen) or special equipment (butt welding machines for resistance welding), or are relatively expensive due to the large labor intensity (arc and forge welding) . In addition to these circumstances, which present certain inconveniences in the production of high-speed cutting tools, these methods are characterized by a number of additional labor-intensive operations, accompanied by considerable waste of hard alloys. For example, when cutting high-speed steel strips into plates, which is carried out by mechanical saws, cutters or cut-off cutters, there is a loss of the material being cut at the cut points. In cases of high-speed steel plate weld- ing on the tool holder, the most common butt-weld method of electric welding, the loss of high-speed steel for reflow and burnout, according to Orgimetal, is 2 to 3 mm thick. In addition, in almost all of these methods, a preliminary cleaning of the surfaces of the plates and holders (in order to ensure a close fit) is required, as well as the preliminary heating of the holders followed by slow cooling (lead bath) after welding.

A significant step forward is the method described in the author's certificate No. 28655. According to this method, hard metals are deposited on soft metals by electric welding using the Slav nova method. The iron rod is undermined by a coating consisting of O-70% ferrochrome, O-80% ferromanganese, 10-40% carbon and 5-20% CAS02 or BaCOg. Ferrochrome and ferromanganese enter the plaster separately or together.

The method according to the invention under consideration is a further development of the method according to the author's certificate No. 28655, and consists in the fact that, in addition to the above-mentioned alloying elements, ferrovanadium, ferromolybdenum and ferro-tungsten are introduced separately or in combination.

The main idea of the method of manufacturing a composite cutting tool under consideration is to transfer the metallurgical process of obtaining high-speed steel from electric furnaces of steel mills directly into the zone of a volt arc between the metal (steel) electrode and the semi-steel steel cutter.

This process is carried out by melting in a volt arc the coated steel electrode, in the composition of which coating all the components necessary for producing steels with the required cutting properties are introduced. At the same time, the stated idea of carrying out the metallurgical process of forming a doped alloy on the surface of an ornamental steel holder provides for the possibility of obtaining various qualities and cutting properties of the weld metal.

Depending on the quantitative and qualitative ratios of the alloyed elements introduced into the plastering, various cutting properties of the deposited tool can be obtained, respectively.

With this method, the losses of the shortage high-speed metal are significantly reduced, and a whole number of additional labor-intensive operations are inevitable, which are unavoidable with the existing methods for manufacturing both high-speed steel and composite tools by welding plates to the cutting metal holders.

The formulations used for the washings are listed in Table 1.

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In addition, a coating composition is proposed that does not contain a ferrovol fram and with a different content of alloying elements in ferroalloys.

The composition of the coating for alloy T-143

The process of making the coating is the preliminary grinding of all components, followed by sieving through a fine sieve, preferably with a number of holes of about 3600 per 1 cm. Grinding can be carried out in ball mills or with a pneumatic hammer.

Sifted components in a dry state should be carefully moved among themselves in certain (according to the quantitative ratio table.

The resulting mixture is diluted on a soda glass with water, taken in a 2: 1 volume ratio, to a thick creamy consistency.

The resulting coating is carefully rubbed, then applied to the surface of the metal electrodes by passing them twice through a funnel of a certain diameter, filled with the prepared coating.

One end of the electrode is not coated with a coating over a length of 25-30 mm to achieve contact with the electrode holder.

The thickness of the last layer of the coating should be 2.5 mm per side, i.e. the diameter of the finished electrode is 9-9.5 mm.

In the mass production of electrodes, it is desirable to use mechanical mechchalkov and coating maschiny.

After applying the first layer of coating, the electrodes are exposed to a natural substance at a temperature of 15-20 ° for 2-3 hours, after which the second layer is applied and also drained.

After the second electrode, the electrodes should be calcined in a real electric furnace at a temperature of 200-250 for 2-3 hours.

At the end of the cake and subsequent cooling, the electrodes are ready for use.

The weight of the coating of one electrode is 60-65 g per electrode - (4 mm in diameter and 400 mm long). The weight of such a finished electrode should be in the range of 102-105 g.

Approximately 3–4 brushes of penetrating cutters are fused with one electrode.

The surface of the finished electrode should be sufficiently smooth with the same cross-sectional diameter throughout its length.

Before surfacing, the electrodes should be checked for moisture by short-circuiting the welding machine. In the presence of moisture, the electrodes should be dried.

For example, cutter technology is provided.

The toolholders of the weld cutters are manufactured, according to the existing drawings, by free forging under a hammer or under a die (of steel 5 or 6 according to OST NKTP 2897).

The cutting tool holders are made of V-7 steel.

When forging, the dimensions of the back corner and the socket for the cladding must be met.

 The nest under the cladding is sampled by an oblique cut from the straight plane to 5-7 mm depth of the holder along the rear edge, 10-12 mm long along the front edge of the tool.

Such a cutter preparation provides the lowest consumption of the weld metal (2.2-2.4 cm per one cutter with a section of 20X30 mm) and working time, ease of sharpening and the lowest consumption of “grinding

“PyroB, with a large number of allowed refills.

With free forging of the holder, the following dimensional tolerances must be maintained:

a) the width and height of the holder z t 1 mm

b) the height of the nest. . : ±: 1 mm

c) „back corner. . ± 2 ° surfacing of cutters is performed in

special molds, in order to give the weld metal the desired shape, metal saving and reduction of grinding work.

The molds are made of graphite plates (waste electrodes of electric furnaces can be used) or red copper,

The molds are made for each type-size cutter in accordance with the drawings of the holders.

The design and dimensions of the mold socket should correspond to such an inclined installation of the cutter, which would ensure, during the deposition, the correct front and rear corners of the cutter. Each side of the mold must be two to three times the width of the holder.

To enable slag flow, the mold dimensions should provide gaps of 1–1.5 mm across the width and depth of the holder holder.

The molds should only be used dry. Surfacing is performed on direct current and alternating current devices, with a welding current of 220 to 250 amperes, depending on the size of the holder.

After the workplace has been prepared, the welded blade places the holder in the appropriate mold in such a way that, after the surfacing, to obtain the rake angle specified in the drawing with a tolerance of ± 2 ° -3 °. In addition, a lateral inclination of the holder 1 to 2 toward the cutting edge of the tool is recommended.

The welder initiates an arc in the middle of the nest and, as the deposited metal appears, brings it to the edge in such a way that the slag enters the gaps of the graphite mold prepared for this purpose. By . least

filling the nest with weld metal, the welder must maintain the arc burning, not interrupting it, and try to get a liquid bath of molten metal. For this purpose, the movement of the electrode along the sides of the socket must be commensurate with the time it is filled with metal, without admitting the blockages of the cutting edges and corners of the future cutter.

Surfacing is performed in one step, without. break.

The output of the burning electrode from the bath is made slowly, with a thickened arc, onto the tool holder, on which the arc is broken.

In order to use the ends of the coated electrodes, the length of which is insufficient for the surfacing of the whole cutter, the welder initiates the surfacing with a short electrode and, as the electrode melts, removes it from the cutting face to the depth of the socket, where it produces tearing of the arc and not producing to cool the metal, quickly replaces the electrode with a new one, initiates an arc at the location of the short electrode breakage, brings the metal to the boil and leads to surfacing on the front face of the tool, melting the metal and the cooled slags.

The cutter is cooled in a graphite mold until the slag darkens. Further cooling of the cutter lead to air.

The sharpening of the weld cutters is carried out on medium soft grinding alundum wheels (with a grain size of 25-35 when stripping and 45-60 when finishing sharpening).

In the process of sharpening, it is not possible to allow overheating of the weld metal until the appearance of flowers of tinge.

Soaking the incisors during grinding is not recommended. For wet grinding, plenty of continuous cooling is necessary.

After sharpening, the cutters are subjected to double tempering at a temperature of 550 °, held for one hour and then cooled in air.

After tempering, finishing the cutter faces on fine-grained stones or on special cast-iron discs using fine-tuning paste is desirable.

The hardness of the weld cutters corresponds to Rockwell scale „С with a load of 150 kg

a) after surfacing. 61-64

b) after two holidays. . . 64-66

Welded tools should comply with the drawings. The weld metal must be dense, without shells, cracks and slag inclusions and have a full penetration with the base metal.

The incisors made according to the method proposed by the present invention were subjected to testing in the laboratory of ROM of the Red Banner Moscow Mechanical Engineering Institute. Bauman.

Four through cutters were presented for testing. Two of them with welded high-speed steel plates were made by them. T. Ordzhonikidze, Rockwell hardness PC 62.

The other two cutters were deposited according to the method described in this copyright certificate. Those and other cutters had the same shape and angles. The test was carried out on the machine Chiss-Defris without cooling. Processed carbon steel by Brinell hardness Pb 200. The results of the comparative tests are shown in the attached table 2.

From Table 2 it can be seen that with a cutting depth t b mm and a feed of 5 1.33 mm one of the cutters with a welded plate at a cutting speed & 26 MiMtiH is just l 10.7S minutes, and the other at the same depth and feed, and at MJMUH just l 0.5 minutes. and sat down. One of the deposited incisors T-28-1 with b, 38 and -30 m1 min just l one time 18.08 minutes, and the second time 17.17 minutes. The second of the built-up incisors T-28-2 once just l 40 min. at 5,, 38, g 26 MJMttH and not sat down, and another time at 2 5,, 38 and v MlMUH sat down after 7 minutes.

From the above tests, it can be seen that the weld cutters turned out to be higher in durability than the cutters with welded high-speed steel plates, obtained from the plant. T. Ordzhonikidze.

Table 2