RU2737611C1 - Manufacturing method of current conducting contact elements - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the field of electric engineering and relates to the manufacturing method of current conducting contact elements, mainly electric brushes and coal contact inserts for current collectors of electric rolling stock, operating under conditions of high current density, considerable vibrations and impact loads. Said technical result is achieved by means of manufacturing method of current-conducting contact elements, which includes production of electro-graphised porous workpieces with finished dimensions of element, impregnation with an aqueous solution consisting of 72.8 wt % furfuryl alcohol, 2.9 wt % of orthophosphoric acid and 24.3 wt % water, first, preparing an aqueous solution of furfuryl alcohol by pouring into the impregnation bath the required amount of furfuryl alcohol, separately preparing water with addition of orthophosphoric acid, phosphoric acid solution was poured into a bath with furfuryl alcohol with vigorous stirring to obtain a density g/cm³ solution 1,120-1,130, then the bath is loaded with workpieces packed into punched boxes and held there for 2-3 hours, after which boxes with workpieces are removed from container and subjected to washing with washing, submerging boxes with workpieces from three to five times in container with water, then washed workpieces are subjected to drying at room temperature for at least 8 hours and further heat treatment in heating devices with holding for 2-3 hours at temperature 140-160°C.

EFFECT: formation of stable and stable varnish element in process of long-term operation, including with high current density in the presence of impact and vibration loads; this improves switching, reduces wear of the element during prolonged operation.

1 cl, 2 ex, 1 tbl

Description

The technical field to which the invention relates

The invention relates to the field of electrical engineering and relates to a method of manufacturing conductive contact elements, mainly electric brushes and carbon contact inserts for pantographs of electric rolling stock operating under conditions of high current densities, significant vibrations and shock loads.

State of the art

A known method of manufacturing conductive contact elements for this purpose, including the preparation of powders mainly from the waste of machining of graphitized structural electrodes, mixing them with phenol-formaldehyde resin, squeezing out the heated mixture through a die (mouthpiece) on a horizontal press for the finished product dimensions (Insert "U" GOST 32680 -2014. Current-collecting elements of contact pantographs of electric rolling stock. General technical conditions, M .: Standard-inform, 2015, 14 pp. - analogue).

The disadvantages of the known method are the low electrical discharge resistance of the elements, especially under operating conditions when exposed to atmospheric precipitation, as a result of which a significant number of zones with traces of arson with chipping of the material are formed on the contact surface, with a sharp increase in the wear of the contact elements from the action of high current density in contact. In addition, this method does not allow for high accuracy of the resulting product dimensions, which also negatively affects the operational reliability of the contact elements.

A known method of manufacturing conductive contact elements, including the manufacture of an electrographitized porous workpiece with ready-made dimensions of a conductive contact element and characterized in that the through pores are saturated by impregnation forcibly using an autoclave with a binder and antifriction additive, and a polymer based on furfuryl alcohol is used as a binder additive, polymerized at a final temperature of 160 ° C-220 ° C in an amount of 5% -15% of the workpiece weight, and then as an antifriction additive - a polymer based on furfuryl alcohol, polymerized at a final temperature of 110 ° C-160 ° C in an amount of 1% -8% by weight of the workpiece (Patent No. 2647498, published 03/16/2018 - prototype). With a number of advantages associated with improving the characteristics of finished conductive contact elements, the method has significant disadvantages. The impregnating solution enters the through pores of the material forcibly using an autoclave at a residual pressure of 0.94 kgf / cm ² , which inevitably leads to a violation of the micropore structure due to the appearance of hydraulic shocks that can disrupt the state of microporosity and preserve it in the finished material during heat treatment of the workpieces, which negatively affects the formation of the polish of the materials in contact with the element (copper contact wire, copper ring, collector, etc.), thereby worsening the conditions for current collection.

Disclosure of invention

The technical result of the invention is the formation of a stable and stable polish element with wear during long-term operation, including with increased current density in the presence of shock and vibration loads. This helps to improve commutation, reduce element wear during long-term operation.

The specified technical result is achieved by means of a method for manufacturing conductive contact elements, including the manufacture of electrographitized porous blanks with finished element dimensions, impregnating them with an aqueous solution consisting of 72.8 mass. % furfuryl alcohol, 2.9 wt. % orthophosphoric acid and 24.3 wt. % water, while at the beginning an aqueous solution of furfuryl alcohol is prepared by pouring the required amount of furfuryl alcohol into the impregnating bath, water is separately prepared with the addition of orthophosphoric acid, the solution of orthophosphoric acid is poured into a bath with furfuryl alcohol with thorough stirring until the solution density is 1.120-1.130 g / cm ³ , then the workpieces packed in perforated boxes are loaded into the bath and kept there for 2-3 hours, after which the boxes with the workpieces are removed from the container and washed together with the workpieces, immersing the boxes with the workpieces three to five times into the container with water, then the washed blanks are dried at room temperature for at least 8 hours and further heat treatment in heating devices with exposure for 2-3 hours at a temperature of 140 ° C-160 ° C.

The proposed method allows to saturate the pores of the element material with an impregnating solution of a certain density in a natural way without the use of expensive autoclaves.

Furfuryl alcohol has a unique ability to wet surfaces and absorb into open pores of graphitized materials. When applying impregnation and filling the pores in a natural way, its content in the material decreases compared with forced filling, but this decrease helps to improve polish formation, commutation and, as a result, wear resistance.

Implementation of the invention

Example 1.

From electrographitized material of the GMZ brand (TU 48 4802-86-97), blanks of current-collecting contact elements of current collectors of electric rolling stock (TU 3497-010-50165580-2009) with dimensions of 30 * 36 * 260.8 mm were made. An aqueous solution of furfuryl alcohol was prepared by pouring 72.8 mass into an impregnating bath. % furfuryl alcohol, previously prepared 24.8 wt. % water mixed with 2.9 wt. % orthophosphoric acid. This solution is poured into a bath with furfuryl alcohol with thorough stirring until a density of 1.120-1.130 g / cm ^{3 is} obtained. Then the blanks packed in perforated boxes are loaded into the bath and kept there for 2-3 hours, after which the boxes with blanks are removed from the bath and washed together with the blanks, immersing the boxes with blanks three to five times in a container with water, with the purpose of excluding sweating of furfuryl alcohol during heat treatment of blanks. Then the washed blanks are subjected to drying at room temperature for at least 8 hours and further heat treatment in a heating cabinet with exposure for 2-3 hours at a temperature of 140 ° C-160 ° C.

The manufactured inserts were tested at the locomotive depot Moscow-Sortirovochnaya Moscow railway. on electric locomotives EP-10. For comparison, we also tested inserts made by the method of the analogue and prototype. In addition, brushes were made from the inserts - samples with a size of 8 * 12.5 * 12.5 mm, which were then tested on a KZK-95D installation when exposed to shock and vibration loads. The test results are presented in the table.

Example 2.

At OJSC Experimental Plant of Electric Coal Products (Elektrougli), electrographitized porous blanks with ready-made EG61A brush sizes were prepared for the EK-810Ch traction motor. The workpieces were impregnated with furfuryl alcohol according to the technology of example 1 with natural saturation of pores with impregnation, the brushes were tested on the stand of the traction motor EK-810Ch in accordance with the protocol No.TSTEKH-539 of JSC Russian Railways in comparison with brushes EG61A of JSC Prozhekornye Ugli (St. Elets), EG61AK of ZAO Electrokontakt (Kineshma), made with forced saturation of pores by means of an autoclave, brushes EG820 LEG Center (Stary Oskol). The results are shown in Table 2.

Conclusion: For use on the EK-810Ch electric motor, according to the test results, the brushes of the EG61A brand of the Experimental Plant of Electric Coal Products (Elektrougli) with natural impregnation saturation and EG61AK of Electrocontact CJSC (Kineshma) correspond. The condition of the polish and the behavior of the brushes should be assessed during long-term performance tests.

Claims (1)

A method of manufacturing conductive contact elements, including the manufacture of electrographitized porous blanks with ready-made dimensions of the element, their impregnation with an aqueous solution consisting of 72.8 wt. % furfuryl alcohol, 2.9 wt. % orthophosphoric acid and 24.3 wt. % water, characterized in that first an aqueous solution of furfuryl alcohol is prepared by pouring the required amount of furfuryl alcohol into the impregnating bath, water is separately prepared with the addition of orthophosphoric acid, a solution of orthophosphoric acid is poured into a bath with furfuryl alcohol with thorough stirring until the solution density is 1.120-1.130 g / cm ³ , then the blanks packed into perforated boxes are loaded into the bath and kept there for 2-3 hours, after which the boxes with blanks are removed from the container and washed together with the blanks, immersing the boxes with blanks three to five times in a container with water, then the washed blanks are subjected to drying at room temperature for at least 8 hours and further heat treatment in heating devices with holding for 2-3 hours at a temperature of 140-160 ° C.