UA125143C2 - Brake pad of railway vehicle - Google Patents

Abstract

A brake shoe of the railway vehicle comprises a metal frame with technological apertures on its outer surface, secured to the friction element made of composite material. To increase the heat dissipation of the brake shoe and to equalize the temperature field on the working surface of the shoe along the inner surface of the metal frame at least three heat conducting elements in the form of elongated protrusions with lateral recesses are made, the outermost of which are located with an offset from the edges of the metal frame in the longitudinal direction up to 150 mm. At least one intermediate heat conducting element is located between the outermost heat conducting elements. The heat conducting elements are made as solid-cast with a metal frame, the proportion of the volume of the metal frame with heat conducting elements is 25-55% of the total volume of the shoe. A non-asbestos material based on a rubber-resin is used as a composite material of the friction element.

Description

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Schedule

The invention relates to the field of railway transport, namely brake pads of railway vehicles.

Technical level

Brake pads are replaceable working parts that belong to the main part of the brake system. The length of braking distances, speed increase and traffic safety depend on the quality of brake pads. Brake pads must have a specified coefficient of friction, little dependent on speed, high resistance against activation and work stably in various climatic conditions.

A known brake pad intended for braking the wheels of a railway car.

The brake pad includes a backing plate that has a predetermined configuration as a curved strip and means for attaching the backing plate to the brake head, which is located at each end of the backing plate. The brake pad additionally includes brake linings attached to the support plate and has a braking surface for engagement with the wheel pair of the railway car (patent 56581732 (В1)).

The disadvantage of the known brake pad is the insufficient provision of heat resistance, due to the absence of a metal insert, the main task of which is to ensure the removal of heat from the friction surface. In addition, the brake pad has a large number of fastening parts, which does not allow to achieve the necessary heat dissipation, and is also a source of formation of corrosion centers in the joints of various surfaces.

A brake pad for use in railway transport is also known.

The composite brake pad includes a support plate that has a stirrup and a braking surface that has a given configuration in the form of a curved strip and a friction element that is made of a composite material of the first type of friction that passes over the surface of the brake pad. The composite brake pad additionally contains a material of the second type of friction, made in the form of at least one discrete insert and cast into the composite material of the first type of friction. The material of the second type of friction is completely incorporated into the composite material of the first type of friction. The composite material of the first friction type erodes due to frictional interaction with the surface of the wheel pair during normal braking operations, and the material of the second friction type exhibits more

It has higher abrasive properties than the composite material of the first type of friction. At least one element of the friction material is connected to the support plate (patent 56241058 (B1)).

The disadvantage of the brake pad is the lack of heat removal elements from the area of contact between the pad and the wheel. In addition, the pad does not contain additional means of fastening the friction element to the support plate, which can lead to possible disconnection (detachment) of the friction element in emergency braking modes.

Also known is a brake pad containing a cast-iron frame in which friction inserts made of carbon-carbon composite material are located. The cast-iron frame of the brake pad is the basis of the structure and the friction element on the friction working surface of the brake pad (patent OA 88410).

The disadvantage of the brake pad is that the friction surface has a large proportion of cast iron, which leads to damage and rapid wear of steel wheel pairs during braking and the formation of a so-called defect on them, such as rolling

The well-known brake pad contains a steel frame, a cast-iron arc-shaped body. The arc-shaped body consists of the main section of the pad body, provided with cylindrical inserts and placed groups, and the profile section of the pad body with a section, equipped with inserts.

The pad has an additional metal frame, on which the cylindrical inserts of the main part of the pad body and the ridge inserts of the profile section are fixed. Cylindrical inserts of the main part of the pad body are made of composite friction material with a friction coefficient higher than the friction coefficient of the base. The ridge inserts of the profile section are made in the form of profile elements and are installed in the section of the block, which is in contact with the ridge surface of the wheel rim and interacts with the side surface of the rail. Inserts are made of anti-friction composite material with a coefficient of friction lower than the coefficient of friction of the base material and an abrasiveness lower than the abrasiveness of the base material and the material of the inserts placed in the main part of the pad body (patent KI 2494901).

The disadvantage of the brake pad is that the use of metals of different chemical composition (cast iron and steel) reduces corrosion resistance, and wear-resistant inserts made of anti-friction composite material can lead to uneven wear of the pad along its width and its distortion in the brake system.

The well-known brake pad of a railway vehicle contains a composite friction element fixed on a metal frame made in the form of a curved strip,

on the surface of which there is a central boss with a hole for placing a check and side bosses, means of mechanical fastening of a composite friction element, a reinforcing plate and metal inserts. Inserts according to one version of the implementation are attached to the metal frame using a threaded connection, and according to another version, the inserts are fixed on the metal frame using a mechanical fastener made in the form of cutouts cut in the metal frame and curved edges of the reinforcing plate, which are included in notches made on at least one side surface of the inserts. The friction element contains transverse grooves made on both sides of each insert in such a way that they are limited on one side by the side surfaces of the inserts (patent OA 115877).

The disadvantage of the known design is that, according to one version of the implementation, the friction element is attached to the metal frame using a threaded connection, and according to another version, the friction element is attached to the metal frame using a mechanical fastener made in the form of cutouts cut in the metal frame , this method of fastening the friction element is not reliable, especially during emergency braking, and may lead to separation of the friction element from the metal frame.

A composite brake pad is known, which is made of metal, in particular cast iron, for a composite brake unit, in particular for railway vehicles, where the composite brake pad is equipped with a main body in the form of a plate and has a support surface on the inner side for the plastic composition of the composite brake unit. The main body is equipped with at least one steel insert, and it is desirable that retaining necks for the plastic composition are provided on the inner side of the main body.

The steel insert does not have a rectangular cross-section along the entire length of the main body, but forms an annular cross-section (application UMO2011006635 (АТ1)).

The disadvantage of this brake pad is that the established percentage ratio of the planes of the working surfaces of the insert and the friction element is insufficient to ensure the necessary heat removal from the friction zone. The pad is also characterized by the absence of structural elements, which would allow the removal of braking products.

The closest is the brake block for railway vehicles, which contains a cast iron rear brake block and a friction material which is rigidly connected to the rear

With brake block. The back of the pad has a curved plate base with an internal support surface for plastic material. The overall braking surface of the brake unit is formed mainly from at least one outer surface of the friction material and, to a lesser extent, from at least one outer surface of the rear part of the brake unit. According to the invention, the base is made without a frame on the longitudinal sides and contains a side wall in the form of a cheek on each transverse side. The friction material is placed between the sidewalls. Each side wall has at least one break, which goes from the upper surface of the side wall in the direction of the support surface and divides the side wall into at least two sections. The edges of the side sections form part of the total braking surface (application

MO2009036830 (Ag)).

The disadvantage of the closest solution is: rapid wear of the friction element during operation (plastics), friction inserts have high wear resistance, as a result of which the characteristics of the frictional contact of the pad with the wheel, the coefficient of mutual overlap, the coefficient of friction, and, therefore, the braking efficiency in general, are reduced. Also, the so-called sidewalls can collapse during emergency braking because their connection to the rear wall of the block is cantilever and its strength may be insufficient due to the small thickness.

The essence of the invention

The invention is based on the task of increasing the reliability and wear resistance of the pad, increasing the heat dissipation of the brake pad and leveling the temperature field on the working surface of the pad due to the high value of heat capacity and thermal conductivity of the metal frame at a given level of the friction coefficient and minimal wear of the wheel pair, to ensure reliable fixing of the friction element on metal frame, as well as ensure more uniform wear along the length of the pad during operation, increase corrosion resistance due to the one-piece construction of the metal frame with heat-conducting elements. Improving heat removal from the friction zone will significantly reduce the number of defects in wheel pairs that occur due to their overheating during braking.

The set task is achieved as follows.

The brake shoe of a railway vehicle, which contains a metal frame, with technological holes made on its outer surface, is fixed on a friction element, which is made of a composite material. According to the invention, along the inner surface of the metal frame, at least three heat-conducting elements are made in the form of elongated protrusions with lateral depressions, the extreme ones of which are located with an offset from the edges of the metal frame in the longitudinal direction, and at least one intermediate heat-conducting element is located between the extreme heat-conducting elements, while heat-conducting elements are integrally cast with a metal frame, the share of the volume of the metal frame with heat-conducting elements is 25-55 95 of the total volume of the pad, and as the composite material of the friction element, asbestos-free material on a rubber-resin basis is used.

The technical result is an increase in the thermal conductivity of the brake pad as a whole and equalization of the temperature field on the working surface of the pad due to the high value of heat capacity and thermal conductivity of the metal frame at a given level of the friction coefficient and minimal wear of the wheel pair. Ensuring more uniform wear along the length of the pad during operation and reliable fastening of the friction element. Increased corrosion resistance due to the design of heat-conducting elements integrally cast with a metal frame, the absence of contact surfaces of metal materials of different nature (chemical composition), which can lead to a corrosive electrochemical process that is intensified by atmospheric phenomena (moisture, active gases in the air, etc.).

At the same time, each of the extreme heat-conducting elements has at least one slot that divides the heat-conducting element into parts, forming heat-conducting areas located along the longitudinal edges of the working surface of the pad, and the intermediate heat-conducting element forms at least one heat-conducting area in the central part of the working surface of the pad. Ensuring uniform distribution of heat-conducting elements on the working surface of the pad and effective heat removal during braking and increases the wear resistance of the brake pad.

At the same time, at least two intermediate heat-conducting elements are located symmetrically relative to the center of the longitudinal section.

At the same time, the heat-conducting elements have a cantilever connection with the rear part of the frame, so their thickness must be sufficient to prevent their destruction during any braking modes.

At the same time, the brake pad of a railway vehicle contains from 3 to 10 heat-conducting elements. With a reduced number of heat-conducting elements, namely less than three, heat removal from the working surface is not sufficient, which leads to overheating of the pad, an increase in heat-conducting elements on the working surface, more than ten, leads to damage or rapid wear of wheel pairs.

At the same time, the heat-conducting elements are made with casting slopes in the direction of the frame, which are 0.2"7...8.07. Thanks to this solution, the heat from the working surface is evenly distributed over the entire plane of the block.

At the same time, the fixation of the friction material on the frame on the surfaces of the heat-conducting elements occurs due to its pressing in a dispersed form and vulcanization under the influence of temperature and pressure. That ensures reliable fastening of the friction element on the frame, and makes it possible to detach it during emergency braking.

At the same time, the asbestos-free material on a rubber-resin basis with the content of reinforcing fibers and impurities ensures the achievement of the surface hardness of the friction element according to

Brinell in the range of 3...35 HB, the coefficient of friction in a pair with wheel steel in the range of 0.06...0.30, the values are given for pads with a low coefficient of friction.

At the same time, the asbestos-free material on a rubber-resin basis with the content of reinforcing fibers and impurities ensures the achievement of the surface hardness of the friction element according to

Brinell in the range of 1.2...10 HB, the coefficient of friction of the pad in a pair with wheel steel in the range of 0.17...0.45, the values are given for pads with a high coefficient of friction.

It was experimentally established that due to the use of asbestos-free friction material on a rubber-resin basis with the content of reinforcing fibers and impurities, the optimal Brinell hardness values for pads with a low coefficient of friction should be within 3...35 HB, and for pads with a high coefficient friction - within 1.2...10 NV. These ranges provide increased wear resistance of the pad. The use of materials with hardness values below the established ranges for each variant leads to rapid wear of the working surface, and the use of material with hardness values greater than the established ranges for each variant can lead to accelerated wear of the wheelset. It was also experimentally determined that the optimal ranges of friction coefficient values for asbestos-free material on a rubber-resin base with the content of reinforcing fibers are: for pads with a low friction coefficient in the range of 0.06...0.30, and for pads with a high friction coefficient of 60 within 0.17...0.45. These ranges are optimal, because within these limits the coefficient of friction remains the most stable for a long time of operation, and also determines the most optimal values of linear wear and contributes to the improvement of wear resistance.

At the same time, the extreme heat-conducting elements are placed along the edges of the working surface or displaced from the edge in the longitudinal direction by up to 150 mm. It was experimentally established that this arrangement gives the most effective distribution of heat-conducting elements on the working surface, taking into account the heat-conducting elements that are located between the extreme elements. When placing the extreme heat-conducting elements more than 150 mm from the edge. towards the center of the working surface, heat-conducting elements accumulate and form areas that lead to uneven wear or even damage to the wheel pair.

At the same time, the metal frame contains a reinforcing insert, which is located in the central part, under the technological opening. Metal inserts also act as elements that compensate for vibration and shock loads during braking.

Graph 1 shows the temperature of the working surface of the wheel as a result of using the claimed pad, marked on the graph with position 1 in comparison with similar pads from the known prior art in which the friction element is fixed to the metal frame using a mechanical fastener, marked on the graph with position 2.

The results of tests of pads on solid cast metal frames showed that the final temperature of the working surface of the wheel using pads on solid cast metal frames when braking from initial speeds of 50 to 140 km/h. on average 30 95 lower than under the same conditions using pads from the known state of the art. The final temperature of the working surface of the wheel when braking from 160 km/h. lower by 4 9U5 when using blocks with solid cast metal frames. The ability to remove heat from the working surface of the wheel is much higher than pads on solid cast metal frames. The use of self-sealing pads significantly reduces the likelihood of defects in wheel pairs, as well as reduces the frequency of ice formation.

List of drawing figures

The proposed invention is illustrated by the following example of its implementation, as well as by corresponding illustrated materials, which depict the following:

From Fig. 1 - General view of the metal frame of the pad with a friction element.

Fig. 2 - General view of the metal frame of the pad from below.

Fig. 3 - Side view of the metal frame of the pad.

Fig. 4 - Section A-A in Fig. 3.

Fig. 5 - View of the metal frame of the pad from above.

Fig. 6 - View of the metal frame of the pad from below.

The depicted materials illustrating the claimed invention, as well as the given examples of specific implementation, in no way limit the scope of claims set forth in the formula, but only explain the essence of the invention.

Detailed description (information confirming the feasibility of the invention)

The brake pad of a railway vehicle contains a metal frame 1 with lateral technological holes 2 made on its outer surface and a composite friction element 3, which is made of asbestos-free material on a rubber-resin base and fixed on the inner side of the metal frame 1. Along the inner surface of the metal frame 1 there are extreme heat-conducting elements 4, which are offset from the edges of the metal frame 1 in the longitudinal direction, and intermediate heat-conducting elements 5, which are located between the extreme heat-conducting elements 4. Heat-conducting elements 4, 5 are made in the form of elongated protrusions with side recesses 8 and integrally cast with the metal frame 1. Also, the brake pad contains a reinforcing insert b, which is located in the central part, under the technological opening 7. Fixing of the friction element C on the metal frame 1 occurs due to its pressing in dispersed form and vulcanization under under the influence of temperature and pressure.

The claimed invention can be used in the construction of brake pads for certain types of railway vehicles, in particular for passenger cars and rolling stock (electric trains). The blocks are made of a metal frame 1, which is made of one-piece casting with heat-conducting elements 4, 5 to the working surface. During the braking process, not only the frictional composite element 3, which is made of asbestos-free material on a rubber-resin base, but also the heat-conducting elements 4, 5 come into contact with the wheel pair.

The presence of heat-conducting elements 4, 5 to the surface of the wheel pair allows the pad to perform a number of functions, the main of which is a significant increase in heat removal from the friction surface of the pad and the pair of wheels, to minimize the wear of the wheel pair.

The invention ensures the stability of the frictional characteristics of the working surface during the entire service life of the pad, reduces the wear of the wheel pair and increases the safety of operation in emergency braking modes.

Claims (9)

FORMULA OF THE INVENTION 1. The brake pad of a railway vehicle, which contains a metal frame, with technological holes made on its outer surface, fixed on a friction element, which is made of a composite material, which is characterized by the fact that along the inner surface of the metal frame, at least three heat-conducting elements are made in the form elongated protrusions with side recesses, the extremes of which are offset from the edges of the metal frame in the longitudinal direction by up to 150 mm, and at least one intermediate heat-conducting element is located between the extreme heat-conducting elements, while the heat-conducting elements are integrally cast with the metal frame, the proportion of the volume of the metal frame with heat-conducting elements is 25-55 95 of the total volume of the block, while the composite material of the friction element is an asbestos-free material on a rubber-resin basis. 2. The brake pad of a railway vehicle according to claim 1, which is characterized by the fact that each of the extreme heat-conducting elements has at least one slot that divides the heat-conducting element into parts, forming heat-conducting areas located along the longitudinal edges of the working surface of the pad, and the intermediate heat-conducting element forms at least one heat-conducting area in the central part of the working surface of the pad. 3. The brake pad of a railway vehicle according to claim 1, which is characterized by the fact that it has at least two intermediate heat-conducting elements, which are located symmetrically with respect to the center of the longitudinal axis. 4. The brake pad of a railway vehicle according to claim 1, which is characterized by the fact that it contains from 3 to 10 heat-conducting elements. 5. The brake pad of a railway vehicle according to claim 1, which is characterized by the fact that the heat-conducting elements are made with cast slopes in the direction of the frame, amounting to 0.27...8.0". 6. The brake pad of a railway vehicle according to claim 1, which is characterized by the fact that the friction material is fixed on the frame on the surfaces of heat-conducting elements due to its pressing in a dispersed form and vulcanization under the influence of temperature and pressure. 7. The brake pad of a railway vehicle according to claim 1, which is characterized by the fact that the asbestos-free material on a rubber-resin base with the content of reinforcing fibers and impurities ensures the achievement of the surface hardness of the friction element according to Brinell within 3...35 HB, the coefficient of friction in a pair with wheel steel in the range of 0.06...0.30. 8. The brake pad of a railway vehicle according to claim 1, which is characterized by the fact that the asbestos-free material on a rubber-resin basis with the content of reinforcing fibers and impurities ensures the achievement of the Brinell surface hardness of the friction element in the range of 1.2...10 HB, the coefficient of friction pads paired with wheel steel in the range of 0.17...0.45. 9. The brake pad of a railway vehicle according to claim 1, which is characterized by the fact that the metal frame contains a reinforcing insert, which is located in the central part, under the technological opening. what -- eh - t -: хх wah . 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