RU2340806C1 - Brake block of railway vehicle - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention refers to railway transport, namely to brake blocks of railway vehicles. Brake block contains composite friction element, metal frame made of steel strip and solid insert welded to it, wire frame, central boss with orifice for splint and two side bosses. Metal frame of steel strip is less in width than wire frame, it is radiussed over brake block rear surface and pressed in brake block rear surface from both sides of solid insert between side bosses and central boss. Wire framework is essentially two closed up frames around block periphery pressed into composite friction element in the rear part of brake block. Inner parts of two closed up frames overlap each other are folded outside rear part of brake block forming an eye for a splint. Side bosses are made of composite friction material. Solid insert has slot open from the side of its rear surface is enclosed in wire frame and pressed in central boss so that its rear surface is in same plane with central boss rear surface. Enhancement of strength of brake block construction and tool-life gain are reached, as well as spoilage reduction in their manufacturing.

EFFECT: enhancement of strength of brake block construction and tool-life gain are reached, as well as spoilage reduction in their manufacturing.

2 dwg

Description

The claimed invention relates to brake devices, namely to brake pads of railway vehicles.

Known cast iron brake pads, including those with a metal frame, manufactured according to GOST 1205-73 "Cast-iron brake pads for railroad cars and tenders. Design and main dimensions. ”

These pads have a positive effect on the rolling surface of the wheel, however, they have a low coefficient of friction and during operation provide low braking performance, and therefore require high tension of the lever gear during braking, do not provide silent and smooth braking of the train, have a large weight (16 kg ), high wear and high cost.

The known technical solution is used for the same purpose as the claimed one, and has a common essential feature “brake shoe”.

Known brake composite shoe containing a composite friction element and a metal (steel) frame (B.A. Shiryaev "Production of brake pads from composite materials for railway cars", Moscow, Chemistry, 1982, pp. 8-13, 70).

The metal steel frame consists of one part - the main strip, and sometimes two parts: the main strip and welded to it on the inside of the reinforcement plate. The main strip of the frame has an external curvilinear contour around the perimeter of the finished block, and in its central part a U-shaped or semicircular protrusion forming a central boss. The central boss of the frame is equipped with holes for the pin (metal bracket). On the main plate of the frame are also two side bosses serving as guides for the check. The central boss serves for fastening the brake pads in the brake shoe by means of checks, and the guides (side bosses) simplify the mounting of checks.

The reinforcing plate is used to give additional rigidity to the frame and increase the reliability of mounting the frame with a friction element.

The reinforcing plate is provided with holes for welding to the main strip, as well as for flowing the friction mixture during molding in order to increase the fastening with the friction element.

Holes and / or half-holes can also be cut out on the main strip with bending of the non-cut out part of the holes inside the block to obtain spikes for flowing into the holes of the friction mass during molding and to improve the fastening with the friction element.

Compared to cast iron pads, brake pads have received much wider use, since they have a higher friction coefficient, lower pressing force and wear resistance, several times longer service life, lower weight, cost, and also provide silent and smooth braking of the train.

However, during the operation of composite brake pads, individual defects may occur, including: thermal cracks on the rolling surface of the wheels, wear of the rolling surface of the wheels, decrease in brake efficiency of pads when water enters the friction zone (rain, snow), as well as in the presence of coal or peat dust and leaves on the surface of the rail.

In addition, with this design, pads with strong vibrations and frosts, the friction element is torn off from the metal frame, and sometimes the metal frame is destroyed in the place of the U-shaped protrusion.

The essential features of the composite brake pad: “friction element”, “metal frame”, “central boss provided with a pin hole” and “side bosses - guides for checks” are common with the essential features of the claimed utility model.

Known block railway vehicle copyright certificate of the USSR No. 518403 (IPC B61H 7/02, 1976), consisting of friction material and a metal frame. The metal frame is a back plate made in the form of two closed frames pressed into the friction material around the perimeter of the block, the internal parts of which are mutually overlapped and bent outward of the back of the block, forming an eyelet for skipping checks. The back plate is equipped with a metal mesh or perforated plate pressed into the friction material. This frame has received the name of mesh-wire in serial production, as it consists of wire and mesh frames.

The main significant external and structural difference between composite blocks with a mesh wire frame and composite blocks with a steel metal frame is that the central boss of these blocks is made of composite material with internal reinforcement, which sharply increases the elastic properties of the block and, as a result, vibration resistance of the pads, and eliminates the separation of the composite material from the frame (see B.A. Shiryaev, Production of brake pads from composite materials for jelly nodorozhnyh cars, Chemistry, 1982, str.9-14). These pads, in comparison with composite pads with an all-metal frame, also have a long service life, lower cost and metal consumption. However, they also have the disadvantages indicated above, characteristic of composite blocks in comparison with cast-iron blocks.

The known technical solution is used for the same purpose as the claimed one and has common essential features with it: “composite friction material” and “wire frame made in the form of the back of the block pressed into the friction material, along the perimeter of the block, two closed frames, the inner parts of which are mutually overlapped and bent outward of the back of the block, forming an eyelet for skipping checks ”,“ the central boss with a hole for the pin and two side bosses are also made of friction composite on the material. "

In recent years, compositional brake pads with solid cast iron inserts have been tested in railway vehicles, which can improve the performance of composite brake pads during rain and icing, increase heat transfer to the environment, and it is better to clean the wheel of various substances that may rail, as well as partially restore the surface of the wheel during normal braking, that is, reduce thermal cracks, sliders, navars, image on the wheel, and fill small cracks with cast iron during its melting at high temperatures.

These pads are called wheel-saving, as they can dramatically increase the resource of the wheel.

Known brake pad, mainly a railway vehicle according to the patent of the Russian Federation No. 2188347 (F16D 65/04, 08.27.2002). The brake pad contains a metal wire frame and a friction part consisting of three inserts fixed to it. The central insert is made of cast iron and equipped with a pin hole, and the other two inserts are made of composite friction material and are located on both edges of the solid insert.

This brake pad allows you to increase the braking efficiency and increase the resource of the wheels, however, it has insufficient strength and service life. The thermal conductivity of cast iron is several times greater than the thermal conductivity of the composite material, and the heat resistance of the composite material is insufficient. At the joints of the cast iron insert with composite inserts, on the surface of their contact during operation, the composite material gradually burns out, as a result of which the brake shoe loses its required stiffness and can be divided into three parts, connected only by a wire frame, during long-term operation. The effect of restoring the surface of the wheel during normal braking is also small and insufficient.

The known technical solution is used for the same purpose as the claimed one, and has common essential features with it: “metal wire frame,“ friction part fixed to it ”,“ solid insert ”,“ friction composite material ”.

Known brake pad of a railway vehicle according to the patent of the Russian Federation No. 52957 (F16D 65/04, 04/27/2006).

The considered brake shoe contains an all-metal frame made of a steel strip with a U-shaped protrusion in its central part, forming a central boss with a pin hole, a composite friction element and a solid cast iron insert.

A solid insert is located in the center of the block and is welded to the metal frame from the inside on both sides of the U-shaped protrusion.

The composite friction material is first molded to a steel metal frame and a cast iron insert in a mold under pressure, and then vulcanized to them in a mold under pressure at a temperature.

The durability and service life of this block is greater than that of the above.

However, the brake pad in question also has disadvantages.

With this design of the pads, providing a rigid structure of the frame as a whole, the required strength of the frame in its U-shaped protrusion, which is obtained by bending a flat steel strip in the stamp, is not provided.

When the steel frame is stamped, microcracks are formed in the bending places, which, with constant vibrations and protrusion loads under severe operating conditions, increase and the frame breaks, and then the weld seam breaks under the influence of increased loads, and one half of the block breaks away from the other half. In addition, due to vibrations and variable loads during severe frosts, the friction composite element sometimes breaks away from the metal frame and the cast iron insert, especially after the surface of the composite friction material burns at the point of contact with the high-conductivity cast iron insert due to its insufficient heat resistance and low thermal conductivity.

The known technical solution is used for the same purpose as the claimed one, and has common essential features with it: “metal frame made of steel strip”, “friction composite element”, “solid insert located in the center of the block and welded to the metal frame ".

According to the patent of the Russian Federation for utility model No. 56522 (F16B 65/04, D22B 19/02, 2006), a brake shoe of a railway vehicle is known that contains a metal frame with a U-shaped protrusion in its central part, a composite friction element and one solid insert located in the central part of the block and welded to a metal frame. The solid insert is made of ductile or ductile iron, and the ratio of the area of the working surface of the solid insert to the total area of the working surface of the block is from 4 to 20%.

Composite wheel-saving brake pads with an insert made of special high-strength cast iron can increase the resource of the wheel, since the type of cast iron used has a ferritic structure and graphite in the form of spherical or flaky inclusions, high mechanical properties, including tensile strength and elongation. Due to this, during braking at high temperatures, cast iron melts and fills microcracks on the surface of the wheel, thereby preventing the further development of these cracks; helps to improve the surface of the wheel and increase the resistance of the wheels to the formation of cracks and other defects. In addition, the insert made of special cast iron, due to its inherent abrasiveness, has a cleaning effect on the wheel at normal and low temperatures, increases the roughness of the wheel and improves the adhesion of the wheel to the rail and the stability of braking efficiency, especially in the autumn-spring period.

However, with this design of the block, during strong vibrations and frosts, the friction element breaks away from the metal frame, and sometimes the metal frame breaks in place of the U-shaped protrusion.

The known technical solution is used for the same purpose and has common essential features: “composite friction element”, “solid insert made of ductile or ductile iron welded to a metal frame”.

The closest analogue is the brake shoe of a railway vehicle according to the patent of the Russian Federation for utility model No. 62188 (F16D 65/04, D22D 19/02, publ. March 27, 2006).

This brake pad contains a composite friction element, a metal frame made of steel strip and a solid insert welded to it located in the central part of the pad, as well as a wire frame, which is two closed frames pressed into the friction material of the back side of the pad along its perimeter, internal parts which are mutually overlapped and bent outward of the back of the block, forming an eyelet for skipping checks, moreover, the metal frame of the steel strip is made less than a width more than the width of the wire frame, bent along the radius of the back surface of the block and pressed into the back surface of the block between the side bosses and under the central boss, and the composite friction element is made of two longitudinal layers of material, and the layer located on the back side of the block has a strength greater than layer located on the working side of the pads.

The pads on the closest analogue have higher resources, strength and reliability of the structure and resistance to vibration, since the central boss is made of durable elastic composite material and reinforced with a wire frame.

However, the design of the pads under consideration is still not strong enough and reliable, due to the presence of drawbacks in the manufacture of brake pads. During the manufacture (briquetting and vulcanization under pressure) of blocks, there may be a change in its design, namely, the bending of a metal strip in the central boss and its displacement together with the welded insert towards its rear surface. In addition, the weld can weaken under the influence of loads during briquetting and during operation, the insert may fall out of the block after thermal destruction of the adjacent friction mass layer.

Briquetting the pads in question is as follows.

First, at the bottom of the mold in the recess intended for molding the central boss, the first sample of the friction material of the inoperative layer is laid and leveled. Then, on the bottom of the mold, a solid insert is assembled with a metal frame of a steel strip, the back to the bottom of the mold, and a wire frame. After that, a second sample of the friction material of the inoperative layer is poured into the mold and leveled. Only after this the third, last hitch from the friction material of the working layer is filled. The mold is closed, the pressure necessary for briquetting a particular friction material is applied, and exposure is carried out under pressure in the range from several to tens of seconds.

During the cold forming of briquettes and their vulcanization in molds under pressure, the composite friction material is compacted with a significant decrease in volume and an increase in density by a factor of 2–3. However, the fluidity of the composite material is quite low and variable, and, for example, for the TIIR-300 composite material currently mass produced in Russia by plants (the old name is 8-1-66), it can fluctuate between 50-100 mm according to Rashig, i.e. . the value can be changed twice, and its friction coefficient is high for the purpose, as with friction material (B.A. Shiryaev “Production of brake pads from composite materials for railway cars”, Moscow, Chemistry, 1982, pp. 38-41 , 54, 56).

Therefore, due to the low, changing fluidity and high coefficient of friction of the friction composite material, as well as large tolerances and errors during hitching, during briquetting and vulcanization of blocks under pressure, there is a displacement, extrusion of the solid insert together with a steel plate welded to it, passing under the central boss, towards the back of the central boss, up to the overlapping of the space in the central boss, intended for drilling a hole under the pin. Therefore, these brake pads are difficult to manufacture and their manufacture is accompanied by a large number of defects. In addition, this leads to deformation of the weld, in connection with which the structural strength of the pads decreases, and when operating under severe conditions, there are cases of separation of the solid insert from the frame.

The known technical solution is used for the same purpose as the claimed one, and has common essential features with it: “composite friction element”, “wire frame, which is pressed into the friction material of the back side of the block, around the perimeter of the block, two closed frames, the inner parts of which are mutually overlapped and bent outward of the back of the block, forming an eye for passing checks ”,“ a metal frame made of a steel strip with a width less than the width of the wire frame, curved along the radius of the back surface of the block and pressed into the back surface of the block between the side bosses and the central boss "and" a solid insert welded to it located in the central part of the block ".

The task to which the claimed brake shoe is directed is to increase the strength of the shoe structure and increase its resource during operation, as well as reduce the marriage in its manufacture.

The problem is solved by the brake pad of a railway vehicle, containing:

- composite friction element, consisting of one or two longitudinal layers, and the layer located on the back side of the block has a strength greater than the layer located on the working side of the block;

- a central boss with a pin hole and two side bosses made of a more durable composite material;

- wire frame, which is pressed into the composite friction material of the back of the block, along the perimeter of the block, two closed frames, the inner parts of which are mutually overlapped and bent outward of the back of the block, forming an eyelet for skipping checks;

- a solid insert located in the central part of the brake shoe, provided with a groove open from the back surface, and welded to a metal frame, inserted into the wire frame and pressed into the central boss so that its back surface is in the same plane with the back surface of the central bosses;

- a metal frame of two steel strips made less than the width of the wire frame, curved along the radius of the back surface of the block and pressed into the back surface of the block on both sides of the solid insert between the side bosses and the central boss.

The essential features of the claimed block: “the solid insert is provided with a groove open from the side of its back surface”, “the solid insert is inserted into the wire frame and“ the solid insert is pressed into the central boss so that its back surface is in the same plane with the back surface of the central boss ", Are distinctive from the essential features of the closest analogue.

Due to the fact that the solid insert has a groove open from the back of its surface, pressed into the composite friction element and two steel plates welded to it from both sides, as well as a wire metal frame pressed into the composite friction element for a length exceeding the length of the solid the insert in its working section (along the length of the block), the formation of a single vertical crack at the point of contact of the solid insert and the composite element is minimized.

A composite friction element can be made of one or two longitudinal layers of two different composite friction materials of different strengths, and the layer located on the back of the shoe has a strength greater than the layer located on the working side of the shoe, for example, due to the increased content in its composition of reinforcing fibers, their range and fiber sizes. The composition of the working and non-working layers is determined in accordance with the purpose and operating conditions of the pads.

The wire frame is currently manufactured in series by cutting pieces of wire with a diameter of 4 mm, bending and welding closed and curved frames from them, then inserting them into each other and welding together at the center of the obtained frame at the point of contact so that their inner parts mutually overlapped and bent outward, forming an eyelet for skipping checks in the central boss after the frame is molded inside the back of the block.

The metal frame is made by stamping from two steel strips with a thickness of, for example, 2-5 mm and a width smaller than the width of the wire frame and bent along a radius equal to the radius of the back side of the block at the place of subsequent location between the central and side bosses before or after welding to a solid insert with both of its sides.

At the junction with the solid insert, the steel strips of the metal frame can be folded parallel to the side surfaces of the insert to improve the fit to the insert and increase the strength of the weld. In order to improve the flow of excess composite mass from the body of the block to the central boss and vice versa when forming the block, and also to improve the fastening of the composite friction element with a metal frame, holes and half-holes with spikes are made in the frame.

The solid insert can be made of special cast iron, for example, high-strength or malleable, by casting the required shape, possibly not requiring further machining.

In order to provide a cleaning, polishing and therapeutic (pouring of cast iron of small microcracks of the wheel material) impact on the wheel over the entire contact surface of the block with the wheel, the cross section of the block with the insert has a shape that does not differ from the shape of the block in its other cross sections. In order to eliminate mold breakage, the insert dimension in cross section may be provided 1-3 mm less than that of the composite friction element.

On the back surface, the solid insert is provided with an open groove. To place the insert in the wire frame, its upper part is made with dimensions of width and length less than the width and length of the hole in the wire frame in its horizontal plane formed after welding from two frames between their inner ends bent outward.

A solid insert is welded to two strips of a metal steel frame symmetrically on both sides.

Installation (placement) of a solid insert with a metal frame welded to it in a wire frame is performed during the operation of the brake shoe briquetting in the mold.

For the convenience of performing the operation of briquetting the pads in the mold, the wire frame can be pre-welded to the solid insert in its upper part at two opposite points along the width of the frame of the wire frame with a point mounting seam.

Figure 1 presents the brake pad of a railway vehicle, where:

1 - composite friction element, consisting of one or two longitudinal layers;

2 - metal frame of two steel plates;

3 - solid insert;

4 - wire frame;

5 - central boss with a hole for the pin;

6 - side bosses;

7 - groove solid insert.

Figure 2 presents a General view of the solid insert assembly with a metal frame made of steel strip and wire frame brake pads of a railway vehicle.

The technology for manufacturing brake pads includes the following steps:

- manufacturing (casting) of cast iron insert;

- the manufacture of two plates of a metal frame from a steel strip by stamping;

- welding a solid insert to both plates of the metal frame;

- manufacturing and welding of wire frame from wire;

- manufacture of composite friction materials for the working and non-working layers;

- alternately laying in the mold a wire frame, a metal frame with a solid insert, a portion of the non-working layer with leveling and a working layer with leveling composite friction materials and subsequent molding under pressure in the press;

- vulcanization of the pads in the mold under pressure and at temperature;

- drilling holes for a check in the brake shoe.

In exceptional cases, when using rusty or contaminated metal reinforcement or when special requirements for the strength of the block are met, the reinforcement can be cleaned of rust, degreasing and glueing using conventional known technologies to improve adhesion and fastening of the metal reinforcement with the composite friction element.

When performing the pads in the manner described in the characterizing part of the utility model formula, the solid insert is rationally connected by a welding method with radially curved steel frame strips of a metal frame, which is pressed into the rear surface of the brake pad between the side bosses and the central boss. The central boss with a pin hole reinforced with vertical elements of a solid insert and a wire frame, together with side bosses is made of durable composite friction material. The entire back side of the block with a depth equal to the thickness of the pressed frame is also made of durable composite friction material. A wire frame is also pressed into the back of the brake pad. The manufacture of a composite friction element from two longitudinal layers makes it possible to better fulfill various requirements for these layers.

The excess heat generated on the working layer in the place of contact of the brake pads with the wheel is removed through a solid insert and a metal frame to the non-working (back) side.

The implementation of the inventive brake pads of a new design with the characteristics indicated in the distinctive part of the formula, allows to increase the strength of the pads design, reduce their marriage in manufacture and increase the life of the pads in operation by eliminating the possibility of spontaneous movement of the solid insert in the central boss in the mold during briquetting and vulcanization under pressure and eliminating the deformation of the welds of a solid insert with a steel frame.

The robust, reliable design of a composite brake pad with a solid insert, for example, from special high-strength or malleable cast iron, in turn, will achieve stable braking performance, including during icing and rain, increase heat transfer to the environment, provide a cleaning and polishing effect on the wheel, fill microcracks on the wheel with cast iron during its melting at high temperatures under normal braking, thereby preventing their further development and increasing the life of the wheel .

Claims (1)

A brake pad of a railway vehicle containing a composite friction element, a metal frame from a steel strip and a solid insert welded to it located in the central part of the block, a wire frame, which is pressed into the friction element of the rear side of the block, around the block perimeter, two closed frames , the internal parts of which are mutually overlapped and bent outward of the back of the block, forming an eyelet for skipping checks, a central boss with an opening under a check and two side bosses made of composite friction material, and the metal frame of the steel strip is made smaller than the width of the wire frame, bent along the radius of the back surface of the block and pressed into the back surface of the block on both sides of the solid insert between the side bosses and the central boss, characterized in that the solid insert is provided with a groove open from the side of its back surface, inserted into the wire frame and pressed into the central boss in this way that its back surface is in the same plane with the back surface of the central boss.

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