JP2001003152A - Brake disk for railway vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight brake disk excellent in wear resistance and moreover excellent in ductility by coating the sliding face of a brake disk which is composed of an Al alloy having a specified elongation percentage, and in which a recessed part has been formed with a wear resistant material. SOLUTION: The brake disk is composed of an Al alloy such as AC4CH having 5 to 15% elongation. As to the part at which a brake pad is slid on the brake disk, not on the whole face but on the required part, a recessed part is formed. For example, round pores or rectilinear grooves dispersed into the whole face of the sliding face are radiately formed. For coating the wear resistant material, a plating method, a thermal spraying method, or the like, is used. As to the plating method, a nickel coating film in which fine ceramics particles are dispersed is desirably used. A ceramics thermal spraying material used in the thermal spraying method is composed of the oxide, nitride, carbide, boride, or the like, of a metal such as Al and Ti. The breakage of a bolt hole part on which stress is concentrated in use can be prevented, and the breakage of the brake disk based on the dimensional difference from a railway vehicle caused by expansion and shrinkage can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake disk for railway vehicles, and more particularly to a brake disk for high-speed vehicles.

[0002]

2. Description of the Related Art Low alloy cast iron has long been exclusively used for brake discs used for R vehicles and Shinkansen vehicles. This special cast iron is commonly called NCM cast iron. The cast iron component contains nickel: 1.0 to 2.0, chrome: 0.3 to 0.6%, and molybdenum: 0.3 to 0.
The matrix contains about 5% of added metal, and the matrix is a pearlite phase strengthened by solid solution of these blended metals, and is composed of a structure in which slightly thick and short graphite is precipitated in a caterpillar shape in the matrix.

[0003] Particularly required as a brake disk for railway vehicles is a friction characteristic that is substantially the same at both normal and emergency stops, that is, when the vehicle speed is high or low at the moment when braking is applied. It has the strength and abrasion resistance to withstand strong pressing force during braking at high speed, and also to withstand this even when the temperature of the sliding surface rises instantaneously, and the thermal crack progresses. It is an important requirement to be extremely slow.

[0004] In this regard, cast iron having a pearlite phase as a mother phase reinforced by solid solution of an additive alloy has high wear resistance because graphite precipitated on the brake sliding surface serves as a kind of lubricant. Also, since it also plays a role of a kind of cushioning material that absorbs deformation due to thermal effects, it is widely used as a brake disc material having excellent characteristics that cannot be obtained with other metal materials. Among them, the friction characteristics described above,
That is, the initial speed at the moment of braking is high (for example, 3
00 km / h), but at a low speed (for example, 30 km / h).
The material characteristic that the coefficient of friction, which hardly changes even in the case of h), is provided, which is the main reason why other materials are distinguished and highly evaluated.

[0005] However, recently, the speed of railways such as the Shinkansen has been increased, and accordingly, there has been a strong demand for weight reduction of parts constituting the vehicle. In particular, the weight of the wheels and the brake discs mounted on these wheels is an unsprung mass that directly applies a load to the rails, which has a significant effect on the vibrations and shocks applied to the rails and the running performance of the vehicle. Has been a challenge.

Accordingly, the idea of utilizing a light metal mainly composed of aluminum has emerged as the most influential means for reducing the weight of a vehicle, and several proposals have already been disclosed.

[0007] JP-A-2-25538 and JP-A-Hei-3
-47945 is one example of this. Looking at the latter, it is an aluminum composite in which ceramics are dispersed and strengthened in an aluminum-based matrix, and specifically, an Al-Mg alloy is used as the aluminum metal matrix. ,
Also, as the ceramics, alumina (Al2O3) or silicon carbide (SiC) is disclosed as an embodiment.

[0008] The reason why the Al-Mg alloy is selected as the parent phase is that the strength decrease due to frictional heat is small. In addition to the effects of the ceramic compounding, it is described that, in addition to the improvement in wear resistance, a phenomenon in which aluminum of the base metal is heated to just before melting and seized due to a rapid rise in surface temperature can be countered.

[0009]

A brake of a railway vehicle is to brake a wheel by pressing a brake pad against a brake disk mounted coaxially with a wheel to brake the brake disk. For this reason, it is necessary to form a hole for passing a bolt for joining to a wheel near the inner periphery of the brake disk. Further, at the time of braking, high stress is applied around the bolt hole near the inner periphery of the brake disc, which is the joint between the wheel and the brake disc, and high strength is required.

[0010] Further, the brake disk repeats the above-mentioned temperature rise due to the friction with the brake pad and the temperature fall due to the traveling wind, and thus repeats expansion and contraction. However, since the wheel does not expand and contract so much, a dimensional difference from the wheel occurs due to expansion and contraction of the rotor. In order to absorb this dimensional difference, elongation was required around the bolt hole of the rotor.

An aluminum composite in which ceramics are dispersed and strengthened in an aluminum-based matrix as described above,
Although it can be used without any problem in strength, it has a problem that cracks easily occur around bolt holes due to low ductility due to stress caused by expansion and contraction of the rotor when used for a long period of time.

Further, an aluminum composite in which a ceramic is dispersed and strengthened in a matrix based on aluminum has no problem with respect to abrasion resistance against sliding with a brake pad. However, when machining such as cutting and grinding is performed during the manufacturing process, it is interrupted because the hard ceramic particles dispersed in the aluminum matrix are machined, resulting in severe tool damage and extremely high machining costs. There was a problem of getting high.

[0013] In order to solve the above-mentioned problems, an object of the present invention is to provide a brake disk for a railway vehicle which is lightweight, has excellent wear resistance and excellent ductility.

[0014]

SUMMARY OF THE INVENTION A brake disk for a railway vehicle according to the present invention has a concave portion formed on a sliding surface of a brake disk made of an Al alloy having an elongation of 5 to 15%, and has a resistance to the sliding surface. Abrasive material is coated.

According to the present invention, by using an Al alloy having a certain degree of elongation, it is possible to prevent damage to the bolt holes where stress is concentrated during use. Further, breakage of the brake disc due to a dimensional difference from the wheel due to expansion and contraction during use can be prevented. While forming a concave part on the sliding surface,
By coating with a wear-resistant material, it can withstand sliding with the brake pad for a long time. Furthermore, even when the wear-resistant material on the brake disc surface is worn by sliding with the brake pad, the wear-resistant material formed in the recess can ensure a certain level of wear resistance, so that it can be used for a long time. .

Further, after processing into a brake disk shape, a wear-resistant material is coated, so that processing is basically only processing an Al alloy, thereby improving workability.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An aluminum alloy having an elongation of 5% to 15% includes, for example, AC4CH. 5% growth
From the above, even if the expansion and contraction of the brake disk due to heat generation due to friction with the pad during use is repeated,
The stress caused by the dimensional difference with the wheel is relieved, so that there is no damage from around the bolt hole near the inner peripheral surface of the disk.

Forming a concave portion on the sliding surface of the brake disk means forming a concave portion on a portion where the brake pad slides on the brake disk, but it is necessary to form a concave portion on the entire surface on which the brake pad slides. However, a concave portion may be formed only in a desired portion.

The concave portion is formed, for example, in a sliding surface by forming round holes distributed over the entire surface as shown in FIG. 1 or linear grooves as shown in FIG. 2 in a radial manner. Alternatively, the strip-shaped grooves extending in the radial direction may be slightly displaced in the circumferential direction, or may be arc-shaped grooves or continuous spiral grooves.

As the wear-resistant material to be coated, a plating method, a thermal spraying method or the like can be used. When a plating method is used, a nickel coating in which ceramic particles are dispersed is particularly preferable. This is because nickel or nickel alloy mainly composed of nickel has abrasion-resistant Ti,
Carbides such as W, Si, B, Mo, Cr, Ti, Cr,
Fine ceramics such as borides such as Mo and nitrides such as Ti and B are dispersed therein.

In the case where the thermal spraying method is used, the ceramic thermal spraying material includes Al, Ti, B, Cr, Mo, Ta, Fe, Si,
Examples include oxides, nitrides, carbides, borides, and the like of metals such as W, Co, Ni, Zn, and Y. More specifically, as the metal oxide, Al2O3, gray alumina, TiO2, Cr2O3, Si
As metal nitrides such as O2, ZrO2, Y2O3, MgO, CaO
AlN, TiN, Si3N4, ZrN, BN, etc.
C, SiC, WC, ZrC, Cr3C2, B4C, etc., and TiB2, ZrB2, MoB2, etc. can be used as metal borides. These ceramics can be used alone or in combination of two or more. There is no particular limitation on the shape of the thermal spraying material, and any material such as powder, wire, rod, etc. suitable for the thermal spraying device may be used. The thermal spraying method is not particularly limited, and a plasma thermal spraying method, an arc thermal spraying method, a gas flame thermal spraying method, an explosive thermal spraying method, or the like can be employed. If the thickness of the sprayed film formed by thermal spraying is too small, the improvement effect of the present invention is low, and if it is too thick, problems such as peeling may occur, so that a sprayed layer having a thickness of 20 μm to 60 μm is laminated up to several millimeters. Good to let.

[0022]

According to the present invention, by using an Al alloy having a certain degree of elongation, it is possible to prevent breakage of the bolt hole where stress is concentrated during use. In addition, it is possible to prevent the brake disc from being damaged due to a dimensional difference from a railway wheel due to expansion and contraction during use. By forming a recess on the sliding surface and coating a wear-resistant material,
It can withstand sliding with the brake pad for a long time. Furthermore, even when the wear-resistant material on the brake disc surface is worn by sliding with the brake pad, the wear-resistant material formed in the recess can ensure a certain level of wear resistance, so that it can be used for a long time. .

[Brief description of the drawings]

FIG. 1 shows the shape of a sliding surface of a railway brake disc according to the present invention.

FIG. 2 shows the shape of the sliding surface of the railway brake disc of the present invention.

[Explanation of symbols]

 1 Brake disk sliding surface, 2 recess

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J058 BA41 BA68 CB11 CB29 EA08 EA14 EA34 EA35 FA21 4K024 AA03 AB12 BA06 BB04 GA03 4K031 AA02 AB08 CB14 CB42 CB44 CB46 CB52 DA01 DA03 DA04 DA06

Claims (3)

[Claims] 1. A brake for a railway vehicle, wherein a concave portion is formed in a sliding surface of a brake disk made of an Al alloy having an elongation of 5 to 15%, and the sliding surface is coated with a wear-resistant material. disk. 2. The brake disk according to claim 1, wherein the wear-resistant material is a plating film in which ceramic is dispersed. 3. The brake disk according to claim 1, wherein the wear-resistant material is a ceramic sprayed layer.