JP2001165212A - Brake disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake disk bearing a long-term use by suppressing the stress concentration into a bolt hole by thermal stress generated by braking. SOLUTION: This brake disk is provided with a plurality of cutouts in its internal circumference and cutout shape parameters R regulated by the following expression (1) of the cutout are set to not less than 2.0 and not more than 8.0. [Expression 1] R=200/200-d[1+2(d/r)1/2]...(1), wherein, (d) and (r) express the cutout depth (mm) and the curvature radius (mm) of the cutout bottom respectively.

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 a railway vehicle. The present invention relates to a brake disk for a railway vehicle that can be used.

[0002]

2. Description of the Related Art Block brakes, drum brakes, disc brakes, and the like are used as mechanical braking devices for railway vehicles, automobiles, motorcycles, and the like. In recent years, disk brakes have come to be used heavily as vehicles have become faster and larger.

A disc brake is a device that obtains a braking force by friction between a brake disc and a brake lining. Usually, a brake is provided on a sliding surface of a donut-shaped disc-shaped disc attached to an axle or a wheel with bolts. A device that obtains a braking force by pressing a lining, and controls the speed of a vehicle by braking the rotation of an axle or a wheel. The disc having the sliding surface is referred to as a brake disc.

[0004] Among these, brake discs for railway vehicles include side discs and shaft mount discs. The side disc is a brake disc fastened to the side surface of the wheel, and the axle mount disc is a brake disc fastened to the axle. Hereinafter, the side disk and the shaft mount disk are referred to as a brake disk, or simply as a disk.

FIG. 4 shows the shape of a conventional brake disk for a railway vehicle, and FIG. 4A is a partial plan view showing a quarter of the brake disk for a railway vehicle, and FIG.
FIG. 3 is a partial cross-sectional view showing a half of a cross section of a railway vehicle brake disc.

As shown in FIG. 1, the brake disk 1 generally includes an outer peripheral portion 2 including a sliding surface 4 and an inner peripheral portion 3 including a bolt hole 5 for fastening to a wheel or the like.

[0007]

DISCLOSURE OF THE INVENTION In a high-speed railway vehicle such as a Shinkansen, the disk rotation speed and the inertia force are extremely large, so that the disk temperature rise under a brake load is higher than that of other automobiles and motorcycles. Remarkably large. for that reason,
In the outer peripheral portion including the sliding surface of the disk, a very large thermal expansion force is generated as the temperature rises. However, since it is restrained by the inner peripheral portion including the bolt hole portion and having a lower temperature than the outer peripheral portion, compressive stress is generated in the outer peripheral portion of the disk in the circumferential direction,
Conversely, tensile stress is generated in the inner peripheral portion of the disk in the circumferential direction.

As a result, since the inner peripheral portion of the disk is fastened and restrained by bolts, significant stress concentration occurs in the fastening bolt holes provided in the inner peripheral portion of the disk,
May be the most dangerous part of the entire disc.
Further, if plastic deformation occurs at the outer peripheral portion of the disk due to compressive stress generated when the temperature rises, tensile residual stress occurs after the temperature decreases. This may cause a thermal crack on the sliding surface.

In general, when a material having a good thermal conductivity such as an Al-based composite material is used, the bolt hole is the most dangerous part, and when a material having a relatively low thermal conductivity such as a steel material is used. , The sliding surface is the most dangerous part.

As described above, particularly in the case of a railway vehicle disk, it is difficult to extend the life of the disk because the disk is repeatedly subjected to severe thermal stress.

In view of the above problems, the present invention reduces the local stress and strain generated at the edge of a fastening bolt hole arranged on the inner peripheral portion of a disk by optimizing the disk shape. An object of the present invention is to suppress the generation and breakage of cracks from a hole and extend the life of a disk.

Conventionally, a notch in the shape of a chrysanthemum seat has been provided on the inner peripheral surface of a disk for a railway vehicle, but these are provided merely for the purpose of enhancing cooling efficiency. However, the shape suitable for relaxing the thermal stress generated by the intended breaking has not been studied in detail.

[0013]

DISCLOSURE OF THE INVENTION The present inventors have studied the provision of a plurality of notches on the inner peripheral surface of a disk in order to disperse the concentration of stress generated in bolt holes in the inner peripheral portion of the disk. As a result of obtaining a notch shape suitable for dispersing stress concentration by FEM analysis, the following knowledge was obtained.

(A) The stress generated in the bolt hole and the plurality of notches has a good correlation with the notch shape parameter R defined by the following equation (1). Alternatively, the strain corresponds to the parameter _Fth defined by the following equation (2), and the stress or strain generated in the plurality of notches corresponds to the parameter _Ftn defined by the following equation (3).

[0015]

(Equation 2)

Here, d: notch depth (mm), r: radius of curvature (mm) of the notch bottom.

[0017]

(Equation 3)

Here,

[0019]

(Equation 4)

## EQU1 ##

[0021]

(Equation 5)

Here,

[0023]

(Equation 6)

## EQU1 ##

(B) The notch shape parameter R is 2.0 or less
By setting the upper limit to 8.0 or less, F _th / F_tn Is 0.
5 or more and 2.0 or less, bolt holes or notches
To suppress excessive stress concentration on any one of the
It is possible to extend the life of the disk.

The present invention has been completed based on the above findings, and the gist thereof is as follows.

A brake disk having a plurality of notches on its inner periphery, wherein a notch shape parameter R defined by the following formula (1) is 2.0 or more and 8.0 for the notches.
A brake disc characterized by the following.

[0028]

(Equation 7)

Here, d: notch depth (mm), r: radius of curvature (mm) of the notch bottom.

[0030]

FIG. 1 shows the shape of a brake disk according to an embodiment of the present invention. FIG. 1A is a partial plan view showing a quarter of the brake disk, and FIG. FIG. 2 is an enlarged plan view of a cutout portion on the inner periphery of the brake disk of FIG.

In the figure, reference numeral 6 denotes a notch on the inner periphery, and the same portions as those shown in FIG. 4 are denoted by the same reference numerals.

As described above, for example, in the conventional disk shown in FIG. 4, remarkable stress concentration occurs in the bolt holes in the inner peripheral portion of the disk due to thermal stress repeatedly generated by braking. On the other hand, in the disk of the present invention, as shown in FIGS. 1A and 1B, by providing a plurality of notches 6 on the inner peripheral portion of the disk, stress concentration is newly applied to the notches. Although generated, stress concentration on the bolt holes 5 can be dispersed and reduced. Furthermore, as a result, the stress generated in the outer peripheral portion 2 of the disk is also reduced, so that the occurrence of thermal cracks in the sliding surface portion 4 of the outer peripheral portion 2 of the disk is also suppressed.

FIG. 2 shows a notch shape parameter R and a parameter F corresponding to the stress or strain generated in the bolt hole.
₁₃ is a graph showing a relationship between _th and a parameter F _tn corresponding to stress or strain generated in a plurality of notches.

As shown in the figure, when the notch shape parameter R is increased, the stress generated in the bolt hole decreases and the stress generated in the notch increases. Further, when the notch shape parameter R is reduced, the stress generated in the bolt hole increases, and the stress generated in the notch decreases.

From this, it can be seen that increasing the notch shape parameter R can reduce the risk of bolt hole portions. However, increasing the notch shape parameter R leads to an increase in the risk at the notch.

[0036] Therefore, in order to suppress the excessive stress concentration to either of the bolt hole or notch is 0.5 or higher the ratio F _th / F _tn parameters F _th and the parameter F _tn 2.0 Or less, that is, the notch shape parameter R needs to be 2.0 or more and 8.0 or less. By setting the notch shape parameter R within the predetermined range, the life of the disk can be extended.

If the notch shape parameter R is less than 2.0, the stress concentration on the bolt hole becomes excessive, and the risk of the bolt hole becomes high. Also, the notch shape parameter R
Is set to more than 8.0, the stress concentration on the notch portion becomes excessive, and the risk of the notch portion increases.

The notch shape parameter R is preferably 2.5 or more and 7.0 or less.

Various shapes can be applied to the shape of the notch.

FIGS. 3A and 3B show typical examples of the notch shape. FIG. 3A shows a semicircular notch portion, FIG. 3B shows a semioval notch portion, and FIG. FIG. 3 is a schematic view showing a semi-elliptical cutout.

The ratio d / r of the notch depth d to the radius of curvature r of the notch bottom is preferably 0.1 or more and 2 or less.
If it is less than 0.1, the effect of dispersing the stress concentration on the bolt hole becomes small, and if it is 2 or more, the stress concentration in the notch becomes excessive. Preferably it is 0.5 or more and 1.5 or less.

It is preferable that the number of the notches is not less than 4 and not more than twice the number of bolt holes. The reason why four or more is preferable is that the stress concentration can be more effectively dispersed by increasing the dispersion starting point of the stress concentration. The reason why the number of bolt holes is preferably not more than twice is that if too many notches are provided, it becomes difficult to set the above notch shape parameter R within an appropriate range.

The notches are preferably provided at substantially equal intervals in the circumferential direction of the disk. This is because the stress concentration can be further suppressed by dispersing the stress concentration more evenly.

Although the present embodiment has been described taking a brake disk for a railway vehicle as an example, the present invention is not limited to this, and is also applicable to a mechanical braking device such as an automobile and a motorcycle.

[0045]

EXAMPLE In order to confirm the effects of the present invention, eight kinds of disks (outer diameter: 725 mm) having different inner peripheral shapes by sand casting using a SiC particle-dispersed Al-based composite material.
Was manufactured and a brake test was performed.

Table 1 shows the shapes of the disks subjected to the test, and Table 2 shows the parameters of the notch.

[0047]

[Table 1]

[0048]

[Table 2]

For the eight types of disks shown in Tables 1 and 2, using a wheel tester modeled on a bogie of the JR Shinkansen, a pair of disks was used to form a sliding surface (sliding surface width: 1).
27.5 mm) on the both sides of the wheel with the outside facing the brake test. As the brake lining material, a copper-based sintered alloy was used, under conditions corresponding to an emergency brake from a traveling speed of 300 km / h. At this time, the wheels stop about 100 seconds after the start of braking, and the disc temperature reaches about 35 seconds.
The temperature rose to 0 ° C. Thereafter, the disk was allowed to cool, and when the disk temperature was lowered to 60 ° C., the wheels were driven again, and the brake test was performed again under the above conditions. This step was repeated 100 times. Further, when a crack was formed in the bolt hole or the notch, the test was stopped there.

Table 3 shows the results of the brake test.

[0051]

[Table 3]

As shown in Table 3, since the test material 6 does not have a plurality of notches on the inner periphery of the disk, stress concentration on the bolt holes cannot be dispersed, and the brake test was performed twice. As a result, a crack was generated from the bolt hole.

Although the test material 7 has a plurality of notches on the inner periphery of the disk, since the notch shape parameter R is out of the proper range and exceeds 8, stress concentration on the notch becomes excessive. In the 13th brake test, a crack was generated from the notch.

Although the test material 8 has a plurality of notches on the inner periphery of the disk, since the notch shape parameter R is less than 2 which is out of an appropriate range, stress concentration on the bolt hole is less. It became too large and cracks were generated from the bolt holes by the five brake tests.

The test materials 1 to 5 have a plurality of notches on the inner periphery of the disk, and the shape parameters of the notches are in an appropriate range of 2 to 8; Both cracks were good without cracking.

[0056]

According to the present invention, the concentration of stress in the bolt hole due to the thermal stress generated during braking can be effectively suppressed, so that the occurrence of cracks from the bolt hole of the disc can be suppressed and the disk can be used for a long time. The brake disk which can endure can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a brake disk according to the present invention, wherein FIG. 1 (a) is a partial plan view showing １ ／ of the brake disk, and FIG. It is the top view which expanded the notch part.

FIG. 2 is a graph showing a relationship between a notch shape parameter R, a parameter F _th corresponding to stress or strain generated in a bolt hole, and a parameter F _tn corresponding to stress or strain generated in a plurality of notches. is there.

FIG. 3 is a schematic diagram showing a typical example of a notch shape;
(A) is a schematic view showing a semicircular notch, (b) is a semi-elliptical notch, and (c) is a semi-elliptical notch.

4A and 4B are diagrams showing the shape of a conventional railway vehicle brake disc, wherein FIG. 4A is a partial plan view showing 1/4 of the railway vehicle brake disk, and FIG. FIG. 3 is a partial cross-sectional view showing a half of the cross section of FIG.

[Explanation of symbols]

 1: Brake disc 2: Outer circumference 3: Inner circumference 4: Sliding surface 5: Bolt hole 6: Notch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Higashiguchi 5-1-1109, Shimaya, Konohana-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. Kansai Works Steelmaking Works (72) Inventor Takanori Kato Osaka-shi, Osaka 4-5-33 Kitahama, Chuo-ku Sumitomo Metal Industries Co., Ltd. F-term (reference) 3J058 BA31 BA46 CB13 CB14 CB17 FA21

Claims (1)

[Claims] 1. A brake disc having a plurality of notches on an inner periphery thereof, wherein a notch shape parameter R defined by the following equation (1) is 2.0 or more for the notches.
Brake disc characterized by being 0 or less. (Equation 1) Here, d: notch depth (mm), r: radius of curvature (mm) of the notch bottom.