RU2309074C1 - Rail vehicle brake shoe (versions) - Google Patents

Abstract

FIELD: railway transport; brake.

SUBSTANCE: proposed brake shoe contains metal skeleton with projection in central part, composite friction member and hard insert. Shoe is furnished with two flat heat insulating elements arranged at both sides of insert between insert and friction and overlapping zone of their contact inside shoe along width and height of shoe. According to second version, shoe is furnished additionally with open slots at both sides from insert between insert and friction member, and overlapping zone of their contact inside shoe along width and height of shoe.

EFFECT: increased reliability of shoe by changing its design to increase heat resistance by preventing thermal cracks in body of friction member and its burning in place of contact with cast iron insert in manufacture and in service.

3 cl, 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 shoes 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 attribute “brake shoe” with it.

Known brake composite pad containing a friction element and a metal (steel) frame (Shiryaev BA "Production of brake pads from composite materials for railway cars", Moscow, Chemistry, 1982, pp. 9-11, 13, 70) .

The metal frame consists of one part - the main strip, and sometimes two parts: the main strip and a reinforced plate welded to it on the inside. The main strip of the frame has an external curved contour around the perimeter of the finished block, and in the center is 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 with obtaining spikes for flowing into the holes of the friction mass during molding and improving 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.

Salient features of the friction element brake pad, metal frame in the form of a “curved main strip with a U-shaped or semicircular protrusion, forming a central boss with holes for the pin, and side bosses” - guides for the checks, as well as “reinforcing plate” welded to the inner side of the main strip are common with the essential features of the claimed invention.

The closest analogue of the claimed block is the brake shoe of a railway vehicle according to the application No. 2005133046/22 (037001) dated 10.26.2005 (decision on the grant of a patent for a utility model from 01.16.2006).

The brake pad in question contains a metal steel frame, a composite friction element, and a solid cast iron insert. The metal frame consists of one part - the main strip, and has a U-shaped protrusion forming a central boss. On both sides of the U-shaped protrusion, behind it from the inside of the main strip, a solid cast iron insert is welded to it along the width of the block, representing a trapezoidal shape in the longitudinal section of the block.

The essential features of the known block "metal frame", "composite friction element" and "solid insert" are common with the essential features of the claimed invention.

The block according to the closest analogue ensures the preservation of the rolling surface of the wheel, and therefore, the increased service life of the wheel while maintaining the increased service life of the pads, and also provides stability and braking efficiency under normal and severe operating conditions.

However, considered by the closest analogue brake pad has disadvantages.

Already in the manufacturing process (vulcanization and heat treatment) of the brake pad, thermal cracks appear in the body of the friction composite element. During the operation of the block, the friction composite element adjacent to the cast-iron insert gradually burns out. This reduces the reliability of the pads. The main cause of defects is a significant difference in the physicomechanical properties of cast iron and composite material, primarily heat resistance, heat conductivity, heat transfer, expansion during heating, strength, and others.

The task to which the invention is directed is to increase the reliability of the block by changing its design to increase heat resistance by preventing thermal cracks in the body of the friction element and its burning at the point of contact with the cast-iron insert during manufacture and operation.

To solve this problem, a brake shoe is used that contains a composite friction element, a metal frame with a protrusion in the central part and a solid insert. The insert in the longitudinal section can usually be in the form of a rectangle, square, trapezoid with straight or radial bases, or another shape. The cross section of the insert has a shape that does not differ from the shape of the block in cross section, but usually having a slightly smaller width and height. The insert is made of solid metal, preferably cast iron, and is attached to the frame on two sides of the protrusion by welding.

A variant of the claimed block is a block, additionally equipped with two flat heat-insulating elements located on both sides of the insert between the insert and the friction element and overlapping their contact zone inside the block in width and height of the block. The elements are made of a material having higher heat resistance, lower thermal conductivity and lower strength than the friction element and the insert material (thermal asbestos and asbestos-free cardboard and paper, mica, and other materials).

Another option of the claimed blocks is a block made with special open grooves filled with air. The grooves are located on both sides of the insert between the insert and the friction element and overlap their contact area inside the shoe in the width and height of the shoe.

The groove is formed by special plates. The plates are made of metal treated on both sides with special substances that prevent them from sticking or shaping to a friction element (for example, calcium stearate). Such plates are removed from the pads during manufacture after heat treatment. The plates can also be made of a material having significantly lower heat resistance and strength than a solid insert and a friction element (for example, printing paper or packaging cardboard). Such plates burn out during the operation of the pads and also form a groove between the insert and the friction element.

The essential features of the claimed brake pads “two flat thermal insulating elements” and “two open slots”, which are “located on both sides of the insert between the insert and the friction element and overlap their contact area inside the pads in terms of the width and height of the pads”, are distinctive from the essential features the closest analogue.

The manufacturing technology of the pads is simple and involves the following steps:

- manufacturing (casting) of a cast iron insert;

- manufacturing (stamping) of a steel frame;

- welding the insert to the frame;

- manufacturing a friction composite mixture;

- laying in the mold of a metal frame with a welded-in insert, heat-insulating elements or special plates and a portion of the friction composite mixture;

- forming the pads in the mold under pressure followed by vulcanization;

- excavation of special steel plates in case of their application.

Figure 1 presents the brake pad, equipped with additional thermal insulation elements, where:

1 - metal frame

2 - ledge,

3 - a hole for the pin,

4 - polymer friction element,

5 - solid insert

6 - the place of welding of the frame and insert,

7 - thermal insulation elements.

Figure 2 presents the inventive brake pad, equipped with a special groove for uniform distribution of heat, where:

1 - metal frame

2 - ledge,

3 - a hole for the pin,

4 - polymer friction element,

5 - solid insert

6 - the place of welding of the frame and insert,

8 - open grooves.

The implementation of the brake pads with flat insulating elements or with special grooves filled with air, allows to reduce the heat transfer from the cast iron insert to the friction element and, therefore, to reduce the temperature in the contact zone of the insert and the friction element, which eliminates the occurrence of thermal cracks already at the stage of manufacture of the block and burning of the friction element during operation. Thus, the claimed technical solution can significantly improve the reliability of the design of the brake pads.

Claims (2)

1. The brake pad of a railway vehicle, comprising a metal frame with a protrusion in its central part, a composite friction element and a solid insert, characterized in that the pad is provided with two flat heat-insulating elements located on both sides of the insert between the insert and the friction element and overlapping them the contact area inside the shoe in the width and height of the shoe. 2. The brake pad of a railway vehicle, comprising a metal frame with a protrusion in its central part, a composite friction element and a solid insert, characterized in that the pad is additionally provided with open grooves located on both sides of the insert between the insert and the friction element and overlapping their area contact inside the shoe in the width and height of the shoe.

Images