JPH09112612A - Embedded block for brake shoe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an embedded block for brake shoe of car whose strength is heightened and reliability is enhanced, wherein the friction characteristics of the resultant brake shoe are improved to a great extent. SOLUTION: A block 7 for a brake shoe of a car is embedded under the friction surface 9 of brake shoe 1 made of cast iron while part is left exposed at the surface. The block 7 is made as a sintered body consisting of ceramic particles and a binder of metal material. At the time of applying brakes, ceramic particles are separated from this embedded block 7 and supplied to the brake friction surface to contribute to increase in the coefficient of friction between the shoe and wheel and also to enhancement of the durability and anti-abrasiveness of the shoe. This sintered block is free from crack initiation owing to the toughness of the binder of metal material even if the braking frequency involving strong impact to the wheel increases.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an embedded block for a brake shoe (brake pad) of a railway vehicle. The embedded block contains ceramic particles and is embedded by exposing a part of the block on the friction surface of the brake shoe. Then, when the block comes into contact with the wheel, the ceramic particles that fall off the block are supplied to the friction surface, and contribute to the increase in the friction coefficient between the brake shoe and the wheel. The invention particularly relates to improvements aimed at improving the strength of such embedded blocks.

[0002]

2. Description of the Related Art A vehicle moving on the ground is equipped with a braking device that uses friction in some form to stop or slow down its movement. Also for rail cars. Tread brakes or disc brakes are installed. The tread brake type brake is a brake of a system in which a brake is pressed against a tread of a wheel to obtain a braking force.

The tread brake system is used in conventional line vehicles of JR companies. In all cases, it is necessary for the conventional line to satisfy the condition that the vehicle stops within a traveling distance of 600 m from the start of braking. Nowadays, the speeding up of trains on conventional lines is being promoted, and there is a demand for the development of brake shoes with excellent braking performance, but the desired material has not been manufactured.

The present inventors have previously proposed Japanese Patent Application No. 4-56396.
So, we proposed a new type of high-performance brake. This method is
Ceramic particles are externally supplied to the brake brake shoe and the friction surface of the wheel to increase the friction coefficient of the same surface. However, in this method, a ceramic particle supply device must be separately provided, and the entire brake device becomes complicated. In addition, the development of resin-based snow resistant bicycles has been under development, but sufficient performance has not been obtained.

Further, the present inventors have previously proposed Japanese Patent Application No. 5-27.
In 4785, we proposed a new type of high-performance brake. In the brake shoe of this type of brake, a ceramic block molded with a material such as glass or cement is embedded. During braking, the ceramic particles that come off from the block due to contact between the ceramic block and the wheel are supplied to the friction surface, which contributes to an increase in the friction coefficient between the brake shoe and the wheel.

[0006]

However, in the above-mentioned prior art, when a ceramic block is formed, a material such as glass or cement is used as a binder for hardening the ceramic particles. Was fragile. Therefore, the ceramic block is apt to be cracked due to the contact of the block and the wheel with a strong impact during the braking operation. As a result, a part or all of the block is excessively dropped with an increase in the number of braking operations, and there is a problem that the effect of frictional force transmission by the ceramic particles cannot be continued. At the same time, measures were required to reduce the steady friction of the brake shoe.

[0007] The present invention has a basic object to provide a brake shoe for a vehicle brake having a friction characteristic significantly improved as compared with a conventional brake shoe. For such a brake shoe, a brake shoe having high strength and improved reliability is provided. The direct purpose is to provide an embedded block for use.

[0008]

In order to solve the above problems, the embedded block for a brake shoe according to the present invention is partly exposed and embedded in the friction surface of a cast iron brake shoe that is pressed against the wheels of a railway vehicle. An embedded block for a brake shoe, comprising: a sintered body of ceramic particles and a metallic binder.

That is, when forming a ceramic block, materials such as crows and cement have been conventionally used as a binder for hardening the ceramic particles as a hard substance, so that there is a problem that cracks easily occur in the ceramic block. On the other hand, in the present invention, the embedded block is formed by sintering using a metallic binder and is embedded in the cast iron brake shoe. From this embedded block, during braking, ceramic particles are separated and appropriately supplied to the brake friction surface, contributing to an increase in the friction coefficient between the brake shoe and the wheel, as well as the durability and wear resistance of the brake shoe. Contribute to improvement. This sintered body block does not generate cracks due to the toughness of the metal-based binder even if the number of braking operations accompanied by a strong impact with the wheel increases, and the ceramic particles that fall off from the block have the above friction. A certain amount is supplied to the surface. This makes it possible to further improve the friction performance and the wear resistance while making the most of the characteristics of the cast iron brake shoe in which the braking performance is stable under the wet condition, particularly the snowfall condition.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, more detailed description will be given with reference to the drawings and embodiments. FIG. 1 is a diagram showing a vehicle brake shoe according to an embodiment of the present invention.
(A) is a side view, (B) is a front view. FIG. 2 shows FIG.
It is a photograph corresponding to (B) showing a state after a brake test of an actual brake shoe. The brake shoe 1 according to this embodiment includes a back metal 3, a brake shoe body 5, and an embedded block 7. The back metal 3 is a mild steel plate (SS40
0) to cover the anti-friction surface 9 side of the brake shoe main body 5 to support the brake shoe main body 5. This is because the brake shoe main body 5 is made of high-hardness cast iron and is apt to be cracked from the frictional heat crack of the friction surface 9 or the like, so that some kind of holder is required.

The brake shoe main body 5 is cast so as to surround the back metal 3 and the embedded block 7. The curved concave surface of the brake shoe main body 5 serves as a friction surface 9 that is pressed against a tread surface (not shown) of the wheel to obtain a braking force. Two embedded blocks 7 are embedded in the upper and lower ends of the brake shoe main body 5. The embedded block 7 is a columnar block, and one surface of the embedded block 7 is exposed to the friction surface 9. When the embedded block 7 is pressed against the wheel, some of the ceramic particles forming the embedded block 7 fall off and are supplied to the friction surface 9, increasing the friction coefficient between the surface and the wheel. Therefore, the braking performance is improved. In addition,
The embedded blocks 7 are arranged at both ends of the brake shoe main body 5 so that the dropped ceramic particles can be supplied to the friction surface 9 even when the wheels are both forward and reverse.

The brake shoe main body 5 of this embodiment is made of special cast iron (NHF). By the way, N used for manufacturing and testing
An example of the components of HF is as follows. C: 3.22 S: 2.02 Mn: 1.22 P: 1.86 S: 0.02 Ni: 0.51 Cu: 0.50 Mo: 1.02 Cu: 0.81

In the embedded block for a bicycle according to the present invention, the metallic binder is copper, aluminum,
It is preferably made of a metal or alloy containing one or more selected from the group consisting of tin, iron and nickel.
This is because these have the following three conditions. Since the melting point is relatively low, the sintering temperature can be low. The worn brake shoe after use is reused as scrap (return material) for casting the brake shoe. At this time, the embedded block is also melted together, so the material of the embedded block must be one that does not erode the furnace wall of the melting furnace. Low cost.

The embedded block 7 of this embodiment is made of Si.
It is a sintered body of copper powder with C (diameter 26 × 45 mm). The molding conditions for this copper sintered block of ceramics are as follows. Average particle size of SiC: 100μ Average particle size of copper: 10μ Mixing ratio of SiC and copper: 2 to 3 (weight ratio) Sintering conditions: 1050 ° C, 60 minutes holding, normal pressure Porosity: 75%

One point of the present invention is that when the embedded block (ceramic / copper sintered block) comes into contact with the wheel, the ceramic particles are appropriately removed. As a suitable block, a method of forming a metal such as brass or bronze in addition to the low-density sintered body as in this embodiment can be considered.

The content of the copper binder (excluding pores) in the embedded block is preferably 30 to 50% by volume. That is, when blocks were actually formed with the copper contents of 49% and 34%, good blocks were obtained. Further, the porosity is preferably 26 to 36%. This is because in this range, the strength and the release characteristics of the ceramic particles have a good balance.

A full-scale brake test was conducted using the brake shoe manufactured as described above. In this test, the brake shoe is pressed against a wheel that has the same moment of inertia as the actual vehicle rotating at a predetermined speed, and the instantaneous friction coefficient, braking distance (rotation distance until stopping) and time are measured. did. The brakes tested were alloy cast iron brakes (NHF) for high-speed vehicles that are currently in practical use, and the copper binder SiC block of the example in which they were cast and rounded brakes (NHF).
/ CuSiC).

FIG. 3 is a graph showing the relationship between the initial braking speed of 155 km / h and the speed at which the wheels are stopped by braking (horizontal axis) and the instantaneous friction coefficient (vertical axis). It can be seen that the friction coefficient of the brakes with embedded blocks is high in almost all regions from the high speed range at the beginning of braking to the low speed range just before stopping. The test also measured the braking distance from the start of braking until the wheels stopped. The braking distance of the product of the present invention is 30% or more shorter than that of the conventional NHF product.

FIG. 4 is a graph showing the relationship between each brake initial speed (horizontal axis) and wear rate (vertical axis). It can be seen that the wear rate of the brake shoe (NHF / CuSiC) in which the block of this embodiment is embedded is low over almost the entire initial speed of each brake. The amount of wear of the brake shoe of the present invention product was about 20% smaller than that of the conventional NHF product.

As described above, the brake shoe for a vehicle brake of the present invention is embedded in the brake shoe main body without any modification of the brake device or installation of an additional device. Due to the function of the ceramic particles supplied from the sintered block of the ceramic and the metallic binder, the durability and wear resistance of the conventional brake shoe brake performance can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a vehicle brake shoe according to an embodiment of the present invention. (A) is a side view, (B) is a front view.

FIG. 2 is a photograph showing a state after a brake test of an actual brake shoe corresponding to FIG. 1 (B).

FIG. 3 is a graph showing a relationship between a speed (horizontal axis) and an instantaneous friction coefficient (vertical axis) from an initial brake speed of 140 km / h until a wheel is stopped by applying a brake.

FIG. 4 is a graph showing the relationship between each brake initial speed (horizontal axis) and wear rate (vertical axis).

[Explanation of symbols]

1 brake shoe 3 back metal 5 brake shoe body 7 embedded block 9 friction surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Junichi Nakayama, 8-8, Komitsu-cho, Kokubunji-shi, Tokyo 38 Inside the Railway Technical Research Institute (72) Inventor, Junji Watanabe 43, Midorigaoka, Ebetsu-shi, Hokkaido (72) Inventor Toshihiko Aoyama 1-4, Kita 38 East Higashi-ku, Sapporo-shi, Hokkaido

Claims (3)

[Claims] 1. An embedded block for a brake shoe, a part of which is exposed and embedded in a friction surface of a cast iron brake shoe that is pressed against a wheel of a railway vehicle; a sintered body of ceramic particles and a metallic binder. An embedded block for brakes that is characterized by: 2. The embedded block for a brake shoe according to claim 1, wherein the metal-based binder is made of a metal or an alloy containing one or more selected from the group consisting of copper, aluminum, tin, iron and nickel. 3. The embedded brake shoe according to claim 1, wherein the metal-based binder is made of copper or a copper alloy, and the content of the metal-based binder in the block (excluding pores) is 30 to 50% by volume. block.