RU2568818C2 - Brake pad - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to railway transport, particularly, to railway transport braking equipment. Claimed brake pad consists of two interconnected carcass and friction element. Said carcass comprises fastening plate for lateral bosses and central boss with central bore to be attached from the carcass rear side. The carcass fastening plate is provided with copper-based film and is bonded by diffusion with aforesaid friction element. In compliance with the first version, the friction element working surface is provided with lapping ply made from 1-5 mm deep cermet material. Note here that lapping ply friction factor makes 20-80% of friction element hardness. In compliance with the second version, the carcass rear side is equipped with vibration-proof set. The latter consists of at least four segments located at contact points or carcass contact parts with the brake shoe contact area.

EFFECT: longer life, higher resistance to higher temperatures and ambient effects.

5 cl, 4 dwg

Description

Technical field

The invention relates to the design of a brake device of a rail vehicle, where the braking effect occurs under the pressure of the brake element on the surface of a moving body, and relates to a brake shoe, which is adapted for mounting in a brake shoe and equipped with a friction element, the working surface of which is in close contact with the circumference of the wheel brace.

State of the art

The deceleration device for rail vehicles, as a rule, is formed by the brake system in the form of a shoe brake. The brake shoe consists of a shoe in which a brake shoe is mounted, with a width of 50 to 60 mm. The brake pad, the working surface of which corresponds to the counterbody, is pressed against the surface of the bandage through the lever mechanism when the rail transport slows down. On the surface of the wheel, a friction force arises, which inhibits the rotation of the wheel or pair of wheels, while the friction forces also have a cleaning and polishing effect. The magnitude of the brake force of the brake shoe depends on the pressure exerted on the brake shoe and on the coefficient of friction between the surface of the wheel and the friction element of the brake shoe.

There are various known arrangement of brake pads, which differ mainly in terms of material, technological and structural performance. For example, in publications CZ 253310 B1, CZ 272668 B1, brake pads with a metal bearing plate are described, which are made by casting of cast iron in casting molds and have a central boss with a pin hole on the upper working area. The check serves for fastening the brake shoe and brake shoe, and the carrier plate is equipped with two bosses, which are intended as guides for the checks, as well as as a brake shoe lock in the longitudinal groove of the brake shoe. As described in US Pat. No. 2,748,902 A, cast-iron brake pads can be made in such a way that a steel frame is poured inside the pads body, the fastener of which is pulled out of the pads. The disadvantage of cast-iron pads is a low coefficient of friction, which is compensated by the high specific pressure between the block and the wheel surface, which reduces the durability of the brake pads.

Currently, in addition to cast-iron brake pads, brake pads made of composite materials are also used, which have a constant coefficient of friction between the block and the wheel. This version of the brake pad requires less pressing force, which entails a decrease in pad wear and provides smooth braking of the vehicle. For example, in publications US 6328143, US 5704454 A, as well as in the scientific literature V.A. Shiryaeva “Production of brake pads from composite materials for railway cars”, Moscow, Chemistry, 1982, pp. 9-14, 70, 71, describes different composite brake pads containing a friction composite element attached to the main plate.

This main plate is formed mainly by a steel plate, and from the central part is equipped with a central boss with a pin hole. On the non-working surface there are also two bosses serving as guiding checks, as well as for fixing the pads in the groove of the shoe. The solutions are also familiar when the main plate is formed in the form of a bent carrier plate with a central U-shaped protrusion, reinforced by an additional plate from the inside, together creating a very rigid frame.

The reinforcing plate is mainly used to ensure the highest reliability of fastening the composite brake element so that its base is cut out of a steel sheet in the form of an elongated octagon, where the faces of the base are bent when pressed in the longitudinal and transverse directions to the side of the working surface of the shoe and form side mounting ribs. The reinforcing plate is also equipped with four holes for connecting to the main plate, as well as for flowing of the friction material during formation, in order to increase the adhesion of the friction material and the main frame.

The disadvantage of composite brake pads is the possibility of the appearance of various defects and violations, such as thermal cracks on the surface of the wheel, wear of the surface of the wheels, lowering of the braking efficiency of pads when the humidity is in the friction zone or in the presence of coal or peat dust, as well as falling leaves on rails surface. Moreover, at rail speeds of more than 160 km / h, high temperatures occur on the surface of the composite brake pads, which entails the loss of performance of the composite materials.

Due to the continuous increase in the speed of rail transport, it is necessary at the brake pads to provide the required measure of reliability in a given period of time. The required performance at speeds above 160 km / h is provided mainly by ceramic-metal brake pads. Of friction materials, iron-based materials are used. The disadvantage of these friction materials is excessive wear, even damage to the surface of the wheel after replacing a worn block with a new one.

Copper-based friction metal-ceramic materials are also known, which, in comparison with iron-based metal-ceramic brake pads, have lower strength, less wear and no damaging properties on the wheel surface. Copper-based friction materials are made by sintering mixtures of basic powders in heat-resistant forms as separate semi-finished products manufactured by cold pressing or sintering together with a steel plate or frame.

For example, publication CZ 1996-510 A3 describes the implementation of a brake pad, which consists of a main and a carrier plate of a metal intermediate layer, which is diffusely connected to a ceramic-metal friction material containing 50-75% copper, 4-7% zinc, 8-11% iron, 5-9% mullite and 8-14% artificial hexagonal carbon. The publication RU 2310779 describes the implementation of a brake shoe containing a curved supporting frame, in the central part a U-shaped boss is formed on the outside of the supporting frame equipped with two fixing washers, and a reinforcing plate coated with copper is attached on the inside, with dimensions corresponding to the base of the friction cermet item.

The carrier plate is first connected to the friction element by sintering technology at high temperature and pressure in the furnace, after which it is welded in several places to the carrier frame in which the holes for welding are made. The disadvantage of this performance brake pads is the fact that the design only solves the strength and reliability of the brake pads, but does not solve the increased noise that occurs when braking.

In this design of the brake system, harmful high-frequency noise occurs at the points of contact of the main plate of the brake pad and shoe, as well as between the supporting frame and the main plate. The main plate and the supporting frame are connected by welding in only eight places, and in places where they are not welded, a very small gap remains. In this gap, under the influence of vibrations of the supporting frame and the main plate, an undesirable noise arises, which in many cases exceeds the hygiene standards several times.

In the place of contact of the wheel and the friction material of the brake pad, increased wear of the wheel surface occurs, where the friction element has very low wear and high durability over the entire contact area. When replacing a worn brake pad, when braking, the new pad never contacts its entire surface with the working area of the wheel, and only touches at some points. When braking, vibrations thus occur, increased noise and local damage to the surface of the wheel and brake pads with high specific pressure appear.

For example, in the publication US 5341904 A describes the implementation of a composite brake pads, which in part of the contact area along the side walls is equipped with a quickly wearing, lapping layer of material with a low coefficient of friction. This design solution is not applicable for brake pads on which friction elements are made of cermet.

The objective of the present invention is to create a completely new design solution of the brake pads with a friction element made of cermet material with a high coefficient of friction, high durability and does not lose its performance even under the influence of high temperatures that occur mainly when braking rail vehicles and moving at speeds above 160 km / h, as well as under the influence of climatic influences.

The friction element is equipped on the contact area with a wear-resistant lapping layer to prevent excessive wear or damage to the wheel area, mainly when replacing a worn block with a new one. The structural solution of the ceramic-metal brake pad completely eliminates harmful high-frequency noise arising in the area of the supporting frame, however, the supporting frame must maintain the requirements of rigidity and reliability.

SUMMARY OF THE INVENTION

This problem is solved according to the invention by creating a brake shoe, mainly intended for brake systems of rail vehicles, removably fixed in the brake shoe and consisting of interconnected frame and friction element made of cermet material, and the frame contains a mounting plate to which from the back side bosses and a central boss with a central hole are attached. The frame mounting plate is equipped with a copper-based film and diffusely connected to the friction element in such a way that a single product is obtained.

In the final version, the friction element on the side of the working surface is equipped with a lapping layer made of cermet material with a thickness of 1-5 mm, in which the friction coefficient of the lapping layer corresponds to the coefficient of friction of the main friction material and the stiffness corresponds to 20-80% stiffness of the friction material.

In the ideal case, the supporting frame in the mounting area is equipped with an anti-vibration kit consisting of at least four anti-vibration segments in the form of longitudinal strips located at the points of contact or in the contact part of the supporting frame with the area of contact of the shoe.

The present invention achieves the highest efficiency with the help of a new constructive solution of the brake pads, eliminates the harmful noise that occurs during braking of rail vehicles, and also provides high strength and reliability of fastening the brake pads. Using a ceramic-metal lapping layer with the same friction coefficient as the main friction material, but with very high wear, a quick grinding of the contact area between the brake pad and the wheel rolling area is achieved.

The lapping layer during the period of several braking adjusts to the shape of the wheel, and the brake pad thereby fits its entire working area onto the wheel brace. This eliminates the harmful noise arising from the imperfect contact of the brake pads to the working surface of the wheel, and also eliminates excessive wear and damage to the area of the wheel with high specific pressure.

Brief Description of the Drawings

A specific embodiment of the invention is shown schematically in the accompanying drawings, in which:

Figure 1 is a side view of the braking system;

Figure 2 is a top view of the brake pads;

Figure 3 is a view in longitudinal section of a brake pad; and

4 is a view in cross section of a brake pad.

The drawings illustrating the invention, and the following example of a specific embodiment, in no way limit the scope of protection described in the description, but only explain the essence of the invention.

An example implementation of the invention

The brake system of the rail transport, shown in figure 1, consists of a shoe 1, in which the brake shoe 2 is installed, and its main plate 21 in shape corresponds to the plane of contact 11 of the shoe 1 and the working surface 22 is adjacent to the plane 51 of the wheel 5.

The brake shoe 2 consists in the main embodiment according to figures 1-4 of a fixed frame 23 and cermet friction material 24, and the fixed frame 23 consists of a main plate 231, made in the form of a flat and longitudinally curved plate, which is coated with a non-specified coating on copper base (e.g. plating). The main plate 231 of the fixed frame 23 is connected to the friction element 24 in a diffusion manner into one whole, while the friction element 24 in the place of the working surface 22 of the brake pad 2 is equipped with a lapping layer 241, also made of cermet material.

The bosses are attached to the frame 231, usually by welding, on the back of the frame 21 of the brake shoe 2. Then, a central boss 232 is provided with a hole in the middle 2321 for passing the check 4, which secures the brake shoe 2 and shoe 1 in the brake system, as well as two side bosses 233 as guide pins 4 for securing the position of the brake shoe 2 in the not shown longitudinal groove of the shoe 1. The brake shoe 2 is also on the back side 21 in the places of the supposed contact or in the part of the supposed contact of the fixing frame 231 with a shoe 1 equipped with three antivibration set consisting of antivibration segments 31 arranged along the edges of the fixing frame 231 in the form of four longitudinal bands.

The manufacture of the brake shoe 2 according to the invention is as follows: a fastening groove 231 of the fastening frame 23 of the required size and shape, which is coated on the surface with a film based on copper, for example, with a galvanic coating of copper, is made of a steel sheet. A cermet mixture is made containing copper, iron, tin, graphite, mullite and other components, after which a friction element 24 is made from this mixture by cold pressing, on which there is a lapping layer 1-5 mm thick with the same friction coefficient as that of friction element 2, but with a hardness of 20-80% lower, which allows at the beginning of operation a quick rubbing to the working surface 22 of the brake pads with an area 51 of wheel 5.

When completing the brake pads 2 from the back of the cermet friction element 24, a fastening frame 23 is placed, coated with copper, and sintered under pressure in the furnace. This creates one compact unit, which at the end of technological operations is calibrated on the press to the required dimensions. The compact connection of the friction element 24 and the mounting plate 231 of the mounting frame 23 eliminated the occurrence of internal vibrations of the brake pad 2, which creates a harmful noise when braking the wheel 5.

Finally, the mounting frame 23 on the rear side 21 of the brake pad 2 is equipped with an anti-vibration kit 3, the anti-vibration strips 31 of which are placed at the points of contact or in the contact part of the mounting plate 231 with the contact area 11 of the brake shoe 1. The anti-vibration kit 3 allows you to eliminate small irregularities between the brake pad 2 and shoe 1, which eliminates the possibility of noise in this part of the brake system, where anti-vibration segments 31 have good resistance to climatic conditions, those perature and pressure that occurs when braking.

The described embodiment is not the only design option for the brake pad 2 according to the invention, when the mounting frame 23 is not necessarily in place of the mounting plane 21 of the brake pad 2 equipped with an anti-vibration kit 3. Also, the friction element 24 is not necessarily equipped with a lapping layer 241 and the mounting frame 23 can be equipped with reinforcing steel sheet for increased rigidity.

Industrial applicability

The brake pad can be used as a part of the brake system of rail vehicles, which are entrusted with stringent operational requirements for observing the norms of noise arising from braking, for example, for transport in enclosed spaces, such as the subway, or high-speed transport moving at a speed of over 160 km / h, such as high-speed railways.

Claims (5)

1. Brake pad (2), intended mainly for brake systems of rail vehicles, removably fixed in the brake shoe (1) and consisting of mutually connected frame (23) and friction element (24) made of cermet material, and the frame (23 ) contains a mounting plate (231), to which side bosses (233) and a central boss (232) with a central hole (2321) are attached to the back side (21), characterized in that the mounting plate (231) of the frame (23) is equipped with a film copper-based and diffusely coupled to friction element (24) in such a way that one whole product is obtained, while the friction element (24) in the place of the working surface (22) is equipped with a lapping layer (241) made of cermet material with a thickness of 1-5 mm, and the friction coefficient of the lapping layer (241) is 20-80% of the hardness of the friction element (24). 2. The brake shoe according to claim 1, characterized in that the frame (23) on the back side (21) is equipped with an anti-vibration kit (3). 3. Brake pad according to claim 2, characterized in that the anti-vibration kit (3) consists of at least four anti-vibration segments (31) in the form of longitudinal strips that are placed at the contact points or contact parts of the frame (23) with the contact area (11) ) brake shoe (1). 4. Brake pad (2), intended mainly for brake systems of rail vehicles, removably fixed in the brake shoe (1) and consisting of mutually connected frame (23) and friction element (24) made of sintered metal, and the frame (23 ) contains a mounting plate (231), to which side bosses (233) and a central boss (232) with a central hole (2321) are attached to the back side (21), characterized in that the mounting plate (231) of the frame (23) is equipped with a film copper-based and diffusely coupled to friction element (24) in such a way that one whole product is obtained, while the frame (23) on the back side (21) is equipped with an anti-vibration kit (3) consisting of at least four anti-vibration segments (31) in the form of longitudinal strips that are placed in places of contact or contact parts of the frame (23) with the area of contact (11) of the brake shoe (1). 5. The brake shoe according to claim 4, characterized in that the friction element (24) in the place of the working surface (22) is equipped with a lapping layer (241) made of cermet material with a thickness of 1-5 mm, and the coefficient of friction of the lapping layer (241) makes up 20-80% of the hardness of the friction element (24).

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