RU2170183C1 - Contact slipper making method - Google Patents

Abstract

FIELD: railway transport or urban electric transport. SUBSTANCE: proposed invention relates to methods of making contact slippers for urban electric vehicles and railway vehicles. Method includes mixing of binder and graphite filler and high temperature pressing of mixture with holding. In process of mixing, finely divided polyethylene in amount of up to 3% is additionally introduced into mixture, and pressing is carried out at temperature of 180-200 C. EFFECT: increased impact strength and service life of contact slipper. 2 cl

Description

 The invention relates to methods for manufacturing a contact insert for current collection of urban electric vehicles and can be used for the manufacture of contact inserts for trolley buses or for the production of current collection devices that allow electric power to be transferred from a contact wire to an electric rolling stock.

 Known methods for the production of carbon-graphite contact inserts by the method of hot dry pressing, which are currently widely used by trolleybus enterprises ([1], pp. 455-457).

 The main disadvantage of the known methods is the low toughness of the resulting inserts, which does not provide the required mileage of more than 500 km.

 Closest to the technical nature of the claimed invention is a method for the manufacture of contact inserts of trolley buses from a polymer composition consisting of a mixture of a thermosetting binder and a carbon filler [2].

 Phenol formaldehyde resin is used as a binder, and electrographite and calcined coke powder are used as a carbon filler. To increase the elastic properties of the material and the number of inserts working off the resource, polytetrafluoroethylene (fluoroplast-40) is additionally introduced into the composition in an amount of 0.5-5 wt.%.

Adding polytetrafluoroethylene to the initial mixture increases the impact strength of the inserts by 1.5–2 times [2], however, it leads to a noticeable rise in the cost of manufactured inserts. In addition, the recommended pressing temperature of 175-185 ^o C is significantly lower than the melting temperature of fluoroplastic-40, which does not allow for uniform distribution of the additive throughout the volume of the insert.

 The inventive method solves the problem of obtaining cheap contact inserts with increased service life by increasing their toughness by introducing into the composition of a fusible polymer having higher elastic properties and low cost.

The problem is achieved in that in the proposed method of manufacturing a contact insert, including mixing a binder and graphite filler, high-temperature drawing of the mixture with exposure, at the mixing stage, crushed polyethylene is additionally introduced in an amount of up to 3%, and pressing is carried out at a temperature of 180-200 ^o C.

 The use of polyethylene as an additive is known in polymer antifriction compositions in order to increase the physicomechanical properties of structural material (RF Patent N 1670911 of January 10, 1996, Bull. 1).

 In the proposed technical solution, the addition of polyethylene is used to increase the spent resource of current collectors (inserts) made of composite electrically conductive material. Thus, the proposed solution has a novelty and inventive step.

An example of a specific implementation of the method:
Composition of the composition: bakelite varnish GOST 901-71 of the mark LAN-1, LAN-3, LAN-4 or LAN-5 in an amount of 30 ± 0.5% by weight; oleic acid - 2 ± 0.2% by weight; powder from oil-fired billets produced at electrode plants according to TU 48-01-69-71 in the amount of 5 ± 0.5% by weight (ash content of the powder is not higher than 2%); powder from graphitized products produced at electrode plants according to GOST 4426-71 in an amount of 60 ± 2% by weight (powder moisture not higher than 0.5%); VD grade polyethylene powder in an amount of 3 ± 0.5% by weight.

Into the bakelite varnish we introduce oleic acid and powder from the oil-burned billets and mix. The resulting mixture is introduced into the mixing machine, pour in graphite and polyethylene powder and mix until all the powder particles are wetted with a binder (at room temperature). Mixing is done in any type of mixer. The resulting press material is unloaded for drying on a metal pallet with a layer of up to 25 mm. The mixture is dried at room temperature not higher than 60 ^o C in drying cabinets with exhaust ventilation. Grinding the dried press material is carried out on jaw or roller crushers to a particle size distribution of not more than 1 mm. The products are pressed in heated molds at a temperature of 180-200 ^o C with a specific pressing pressure of 300-400 kgf / cm ² and exposure under pressure of 20-40 s per 1 mm of sample thickness. All products are subjected to heat treatment at a temperature of 175-185 ^o C for at least 10 minutes per 1 mm of the product.

 This method allows to obtain products of increased impact strength and, as a result, the service life of the contact insert also increases significantly.

Sources of information:
1. I. S. Efremov. Trolleybuses, textbook for high schools, M: Higher school, 1969, 488 pp.

 2. RF patent N 2138107 from 09/20/99. Bull. N 26. - prototype.

Claims (1)

A method of manufacturing a contact insert, comprising mixing a binder and graphite filler, high-temperature pressing the mixture with aging, characterized in that at the mixing stage, finely ground polyethylene is added in an amount up to 3%, and pressing is carried out at a temperature of 180-200 ^o C.