RU2510309C1 - Method of compacting electric machine brush billets from carbon-based powders and multicavity mould to this end - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to powder metallurgy, particularly, to production of brushes from carbon-based powders. Brush workpiece is made in multicavity mould by vertical compaction. After vertical compaction, horizontal reduction force is applied from the side of the bush working end to make 10-15 % of vertical compaction at specific force of horizontal compaction 30-40% larger than specific vertical compaction force. Multicavity mould comprises female die 1, top vertical male die 2, chase 3, fixed male dies 4, set of cavity inserts to male cavities 6 to be filled with powder. Horizontal male die 8 and extra vertical male die 10 are conjugated in inclined surface 9 with inclination angle α=10…15 to the mould vertical axis. This mould incorporates the element designed to return horizontal male die to initial position and composed by resilient element.

EFFECT: higher density and strength, lower specific resistivity.

2 cl, 6 dwg

Description

The invention relates to powder technology, in particular to pressing the blanks of brushes of electric machines from carbon-based powder materials.

A known method for the production of brushes for electric machines, in which semi-finished products are pressed in the form of blocks for a large number of brush blanks from carbon-based powder materials (artificial graphite - bunch) (RF GOST R 52157-2003). Then this block is cut into individual blanks and machined to the desired size. The block, designed to obtain 27 blanks of brushes by mechanical cutting, is shown in Fig. 82 (Temkin I.V. Production of carbon products. - M.: Higher school, 1975, p.142).

According to GOST R 53617-2009 in force in the Russian Federation, the sizes of brushes similar in shape to rectangles are in the ranges: thickness from 1.6 to 32 mm, width from 2.0 to 50 mm, height from 4.0 to 80 mm.

The disadvantage of this method is the low productivity due to the subsequent after pressing cutting the block into individual blanks and their machining, as well as low quality.

A known mold for pressing a brush of electric machines, containing a matrix, a vertical punch (Temkin I.V. Production of electric coal products. - M .: Higher school, 1975, p. 108, Fig. 64). In such a mold, the brush blanks are pressed individually.

The main disadvantage of this mold is the low productivity due to the fact that the pressing of the brushes is done individually.

The closest in technical essence and the achieved effect of the proposed method is a method of pressing products from powder materials based on carbon in a multi-cavity mold (RF Patent for utility model No. 115261, license mold for pressing powders, IPC B22F 3/03, from 27.04 .2012). Vertical compression in a multi-cavity mold gives products, which increases the productivity of the manufacturing process of products in comparison with the aforementioned analogue. However, due to the action of active efforts only on the thickness of the workpieces, the sides of the workpiece, including the future working surface, are compressed by its low reactive forces from the sides of the mold. In this regard, the future working surface of the brush has a reduced density, strength and wear resistance, as well as increased electrical resistivity. It should be noted that in the manufacture of blanks for brushes of electric machines, one of the ends of a rectangular brush in the direction of applying the working effort of the working end faces increased requirements for density, strength and wear resistance, which cannot be achieved by the method according to the closest analogue, which reduces the service life of the brushes.

Thus, the disadvantage of the closest method is the low quality of the resulting brushes.

A multi-seat mold for pressing articles made of carbon-based powder materials is known, which contains a matrix, a holder, a set of lower punches, a set of inserts forming cavities for filling powder, an upper puncheon (RF Patent Utility Model No. 115261, license mold for pressing powders, IPC B22F 3/03, dated 04/27/2012). The upper vertical punch is made in the form of a single flat plate with a size along the outer contour corresponding to the size of the inner contour of the matrix. The liners are spring loaded relative to the cage with elastic elements.

The disadvantage of this mold is the low quality when pressing the brush blanks of electric machines.

The task of the invention is to improve the quality of the resulting brushes of electric machines.

The problem in the present method is solved by the fact that in the known method of pressing the blanks of the brushes of electric machines from powder materials based on carbon, in which the blank is pressed in a multi-seat mold by vertical compression, according to the proposed solution, after vertical compression in thickness, a horizontal one is applied to the working end surface of the workpiece compression of 10 ÷ 15% of the vertical compression, and with a specific force of 30 ÷ 40% greater than the specific vertical force.

The problem in the inventive mold is solved in that a multi-seat mold for pressing brush blanks of electric machines made of carbon-based powder materials, containing a matrix, a holder, a set of lower fixed punches, a set of inserts spring-loaded relative to the holder, forming cavities for filling the powder, the upper a punch having a contour with a size corresponding to the size of the inner contour of the matrix, according to the proposed solution, it is additionally equipped with a horizontal punch having a slope th surface disposed at an angle α = 10 ÷ 15 ° to the vertical axis of the mold, a conjugate with additional vertical inclined surface of the punch, and the punch element returns to its original horizontal position.

The fact that after vertical reduction in thickness the horizontal compression of the surface from the side of the working end of the brush blank is performed makes it possible to work on the working surface of the brush, increasing its density, wear resistance and strength, and reducing the electrical resistivity.

An increase in horizontal compression of more than 15% of the vertical compression, as well as an increase in the specific pressing force of more than 40%, leads to the possibility of micro- and macrodefects, and a decrease in horizontal compression of less than 10% of the vertical compression, as well as a decrease in the specific pressing force less than 30% of the vertical force, does not allow to achieve the necessary density, strength of the working section of the brush.

Increasing the angle of the inclined surface of the horizontal punch more than 15 ° will lead to the appearance of defects, reducing it to less than 10 ° does not allow to improve the quality of the brushes.

The method is as follows.

The carbon-based powder material is poured into a multi-unit mold and crimped with the required vertical compression with the required specific pressing force. After vertical compression, horizontal compression of 10 ÷ 15% of the vertical compression and with a specific pressing force of 30 ÷ 40% greater than the vertical specific force is carried out. The values of the compressions and specific compressions depend on the grade of material and the size of the brushes made.

The proposed multi-seat mold is shown in figures 1-6, where figure 1 shows a General view of the mold, figure 2 - section aa figure 1, figure 3 - section bb figure 2 , Fig.4 is a General view of the mold at the time of pressing, Fig.5 is a section aa of Fig.4, Fig.6 is a section bB of Fig.5.

The inventive mold consists of a matrix 1, a vertical punch 2, a holder 3. The upper punch 2 has a contour with a size corresponding to the size of the inner contour of the matrix 1. Between the fixed punches 4 there is a set of inserts 5 forming cavities 6 for filling the powder. Between the cage 3 and the inserts 5 mounted elastic elements 7. The mold is equipped with a horizontal punch 8 made with an inclined surface 9 located at an angle α = 10 ÷ 15 ° to the vertical axis aa of the mold. There is an additional vertical punch 10 associated with the inclined surface 9 of the horizontal punch 8. An additional vertical punch is in contact with the ejector 11 provided with an elastic element 12. The horizontal punch 8 is equipped with an element for returning it to its original position in the form of an elastic element 13.

The mold works as follows.

The carbon-based powder material is poured into the cavities 6 of the mold formed by the set of inserts 5. The drive (not shown) of the upper vertical punch 2 is turned on. Moving downward, the punch 2 compresses the elastic elements 7 through the inserts 5 and forms the powder material located in the cavities 6 between the stationary lower punches 4, the inserts 5 and the matrix 1, forming separate brush blanks. After the end of the stroke of the punch 2, a drive (not shown) of an additional vertical punch 10 is turned on, which, moving downward, acts with its inclined surface 9 on the horizontal punch 8, moving it towards the working end of the pre-pressed workpiece and deforming the brush working section.

After completion of the molding process, the brush blanks are retracted upward by the upper vertical punch 2. Moreover, under the action of elastic elements 7 located between the cage 3 and the inserts 5, the latter return to their original position. An additional vertical punch 10 under the action of the ejector 11 and the elastic element 12 is pushed up, and under the action of the elastic elements 13, the horizontal punch 8 is returned to its original position.

According to the proposed method and mold, 10 blanks of K1 type brushes were made according to GOST 53617-2009 with dimensions 8 × 20 × 50 mm from a powder material containing 86% graphite according to TU 1916-109-71-2000 and 14% phenol-formaldehyde resin SPF -011A according to TU 6-05751768-35-94. The density of the working surface of the brushes was 1.73-1.75 g / cm ³ with horizontal compressions of 10-15% of vertical, equal to 50-55%, specific pressing forces of 30-40% of the vertical forces of the main punch, equal to 60-65 MPa , and angles α = 10-15 °.

The proposed method and mold will find their application in powder technology, electrical engineering in the production of brushes for electric machines used for supplying and removing current on collectors and contact fingers of electric machines.

Claims (2)

1. The method of pressing the blanks of the brushes of electric machines from carbon-based powder materials, in which the blanks are pressed in a multi-seat mold by vertical compression, characterized in that after vertical compression in thickness, horizontal compression is applied to the working end surface of the workpiece, comprising 10-15% of vertical compression, and with a specific pressing force, 30-40% greater than the vertical specific pressing force. 2. a license mold for pressing the blanks of brushes of electric machines made of carbon-based powder materials, containing a matrix, a clip, a set of lower fixed punches, a set of inserts spring-loaded relative to the clip, forming cavities for filling the powder, an upper punch the size of which along the outer contour corresponds to the size the inner contour of the matrix, characterized in that it is additionally equipped with a horizontal punch having an inclined surface located at an angle α = 10-15 ° to the vertical si molds, coupled with the inclined surface of the additional vertical punch, and the element to return the horizontal punch to its original position.

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