RU2508177C1 - Method for obtaining contact inserts of trolley buses - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: powder composition based on carbon is extruded from a press container through a mouth-piece with formation of a profiled working surface of the insert and further division of the obtained semi-finished product into separate workpieces. The semi-finished product is extruded in the form of two workpieces of inserts with opposite lying profiled surfaces, which face to each other with their bottoms; with that, powder composition is divided with a divider along the extrusion axis into two workpieces of inserts. After the profiled surfaces of workpieces leave the mouth-piece, they are calibrated in a four-roll gauge formed with two smooth and two drive calibrated opposite lying rolls, with crimping equal to 5-10%.

EFFECT: improving quality of the obtained inserts by eliminating bending as to length and increasing density and strength of their working profiled surface.

2 dwg

Description

The invention relates to powder technology for the production of electrical products, in particular to methods for producing contact inserts of trolleybus current collectors from carbon-based powder compositions.

A known method for the production of contact inserts from carbon-based compositions, including the operation of mixing a filler from graphite powder and a binder from a powder of phenol-formaldehyde resin, compacting the composition in a mold at a given temperature and specific force and subsequent heat treatment of the obtained semi-finished product (RF Patent for the invention No. 2267411 , a method of manufacturing contact inserts, IPC B60L 5/08, H01R 39/26, from 10.06.2004).

The main disadvantages of this method are the reduced density of products, especially on the shaped contact surface of trolley bus inserts (Certificate for Utility Model of the Russian Federation No. 39541, contact insert of trolley bus current collectors, IPC B60L 5/08, dated 10.08.2004), as well as the low productivity of the method. The low productivity of the method is due to the single-piece compaction of products (inserts) in the mold, the duration of the operations of filling the mold with the powder composition and the extraction of products from the mold, as well as the low speed of compaction. It is known that for at least partial removal of atmospheric gases and vapors from the powder filling in the mold, the speed of movement of the mold punch should be 5-30 mm / s (Temkin I.V. Production of electric coal products.- M .: Higher school 1975, p. 107).

The reduced density of the contact surface of the products reduces their strength, wear resistance and performance, and also increases the values of their electrical resistivity. The low productivity of the method increases the cost of products.

The closest in technical essence and the achieved effect of the proposed method is a method of obtaining products from compositions based on carbon, for example brand BH504Z4, extrusion (Prospect SCHUNK KOHLENSTOFFTECNIK / Carbon sliding strips for Pantographs and Trolley Pole Systems, p.12.). The extrusion process is conducted from the heated composition in a press container. After extrusion, the resulting semi-finished product is divided along the length, obtaining individual blanks of the inserts. Extrusion lead through the mouthpiece. In the domestic technical literature, this method of pressure treatment of carbon-based powder compositions is called the “extrusion pressing” process.

This method in comparison with the aforementioned analogue due to the continuity of its implementation increases the productivity of the method.

However, since the extrusion in this method leads to an asymmetric profile, it is very difficult to combine the axis of application of the pressing force with the geometric axis of the center of gravity of the formed workpiece profile of the contact insert, and the slightest deviation of these axes causes the workpiece to bend along the length, causing inhomogeneity in the cross section of the stress field, which reduces the quality of the resulting blanks.

In addition, the maximum normal compressive force in this method is applied to the end face of the future insert, low reactive force is applied to the contact surface of the insert from the inner side surface of the press container. In this regard, the density of the profile contact surface will be reduced.

In addition, extruding through the mouthpiece of only one preform insert reduces the productivity of the method.

The task of the invention is to improve the quality of the resulting contact inserts by eliminating bending along the length and increasing the density and strength of their working profile surfaces.

The problem is solved in that in a method for producing contact inserts of trolley buses, in which powder compositions based on carbon are squeezed out of a press container through a mouthpiece with molding a profiled work surface and then dividing the obtained semifinished product into separate blanks, according to the invention, the semifinished product is extruded in the form of two facing to each other with their soles of blanks of inserts with opposing working profile surfaces and when extruding the powder composition yayut divider along the extrusion axis on two blanks inserts, and after leaving the die surface profiled workpieces calibrated compression 5 ÷ 10% in the four-high caliber formed by two smooth and grooved opposing two drive rollers.

Due to the fact that in the proposed method a symmetrical semi-finished product is squeezed in the form of two insert blanks facing each other with their soles, the profile bending is eliminated, which will improve the quality of the workpieces, reduce the bending, and further calibration, which is carried out after extrusion without additional heating.

Calibration of profile surfaces of a symmetric profile in a four-roll gauge will increase the density, hardness and strength of the profile surface to a depth of 3 to 5 mm, as well as work out the entire structure of the insert blank, which will improve quality by reducing the inhomogeneity of the stress field over its cross section.

The simultaneous extrusion of two blanks will increase the productivity of the method.

Compression of less than 5% will not significantly increase the density and strength of the profile surface of the insert, compression of more than 10% can lead to defects or destruction of the workpiece.

Compression of the workpiece insert is carried out only by calibrated drive rolls, side rolls are used to maintain the workpieces.

The proposed method is schematically illustrated in figures 1, 2, where figure 1 shows a General view of the line for receiving contact inserts, figure 2 - section aa of figure 1.

On these figures marked 1 - container press; 2 - mouthpiece; 3 - calibrated drive rolls; 4 - smooth rolls; 5 - divider.

The method is as follows.

The carbon-based powder composition heated to about 170-180 ° C is loaded into the press container 1 and squeezed out through the mouthpiece 2 with a divider 5, simultaneously molding and separating the powder composition into two insert blanks facing their soles. After exiting the mouthpiece 2, the specified semi-finished product in the form of two blanks facing each other with soles, separated by a divider 5, is set into a four-roll gauge formed by calibrated drive rolls 3 and 4 smooth rolls, where the profile surfaces of the blanks are calibrated with a compression of 5-10%. After that, the semi-finished product in the form of two paired blanks is fed to the cutting section, where it is divided along the length into separate blanks.

According to the claimed method, trolleybus inserts with dimensions were made: length - 86 mm; width - 27 mm; the maximum height is 19 mm from a composition containing 86 wt. % graphite and 14 wt. % phenol-formaldehyde resin type. Extrusion of the semi-finished product in the form of two inserts joined to the soles of the inserts was carried out from a composition heated to 170 ° C. After exiting the mouthpiece and caliber, the semi-finished products with a length of 4-6 m were measured for longitudinal bending along the axis. No longitudinal bending was detected. The semi-finished product was calibrated according to the working profile surfaces of the inserts in a four-roll caliber, the lower and upper rolls of which were driven calibrated, with reductions: 5; 7.5; 10%. Then the resulting semi-finished product was divided along the length into individual blanks of the inserts. The density of the obtained blanks inserts increased by 4% compared with the closest analogue.

The proposed method will find application in the production of contact inserts from compositions based on carbon, obtained mainly from waste electrode production, and used in urban trolleybuses.

Claims (1)

A method for producing contact inserts of trolleybus current collectors, in which carbon-based powder compositions are extruded from a press container through a mouthpiece to form a profiled work surface and then divide the resulting semi-finished product into separate blanks, characterized in that the extrusion is carried out to obtain a semi-finished product in the form of two facing each other with their soles, blanks of inserts with opposite working profile surfaces and when squeezing out the powder composition is divided by a cut elem along the extrusion axis on two blanks inserts, and after leaving the die surface profiled workpieces calibrated with compression of 5-10% in the four-high caliber formed by two smooth and grooved opposing two drive rollers.

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