JP2002048167A - brake disc - Google Patents

Abstract

(57) [Problem] To provide a brake disc that can withstand long-term use by suppressing stress concentration on an edge portion of a bolt hole due to thermal stress generated by braking. SOLUTION: In a brake disc 11 comprising an outer peripheral portion 13 having a sliding surface 15 and an inner peripheral portion 12 having a bolt hole 14, the inner peripheral portion 12 has a plurality of cuts formed by a slit portion 2 and a cutout bottom portion 3. The notch 1 is provided, the width of the notch bottom 3 is larger than the width of the slit 2, and the notch bottom 3
Is a continuous curve having no inflection point as an outline.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a brake disk for a railway vehicle, and more particularly to a method for reducing the occurrence of cracks from the edge of a bolt hole by reducing local stress generated at the edge of the bolt hole. The present invention relates to a brake disc that can withstand long-term use.

[0002]

2. Description of the Related Art Block brakes, drum brakes, disc brakes, and the like are used as braking devices for land transportation machines such as railway cars, automobiles, and motorcycles.
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.

Among these brake discs, there are side discs and shaft mount discs as brake discs for railway vehicles. 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. 1 shows a shape of a conventional brake disk for a railway vehicle, and FIG. 1A 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 FIGS. 1 (a) and 1 (b), a brake disc 11 generally has an outer peripheral portion 1 having a sliding surface 15.
3 and an inner peripheral portion 12 having a bolt hole 14 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,
At the outer peripheral portion having the disk sliding surface, a very large thermal expansion force is generated as the temperature rises. However, since the disk is restrained by the inner peripheral portion, which has a bolt hole edge portion and is lower in temperature than the outer peripheral portion, a compressive stress is generated in the outer peripheral portion of the disk in the circumferential direction, and conversely, the inner peripheral portion of the disk has Tensile stress occurs in the circumferential direction.

As a result, since the inner peripheral portion of the disk is fastened and restrained by the bolts, remarkable stress concentration occurs at the edge of the bolt hole for fastening provided on the inner peripheral portion of the disk, and the inside of the entire disk is May be the most dangerous part. 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.

Particularly, in the case of a disk for a railway vehicle, it is difficult to extend the life of the disk because the disk is subjected to such severe thermal stress repeatedly. The present invention has been made in view of the above problems, and by optimizing a disk shape, it is possible to reduce local stress / strain generated at an edge portion of a bolt hole for fastening provided on an inner peripheral portion of a disk, and to reduce a bolt hole edge. It is an object of the present invention to suppress the occurrence and breakage of cracks from a part and to prolong the life of a disk.

[0010]

Means for Solving the Problems The present inventors have considered providing a plurality of notches on the inner peripheral portion of the disk in order to disperse the stress concentration generated at the edge of the bolt hole on the inner peripheral portion of the disk. Then, a notch shape suitable for dispersing stress concentration was obtained by FEM analysis, and as a result, the following knowledge was obtained.

(A) If the plurality of notches provided in the inner peripheral portion of the disk are formed in a slit shape, for example, the notches are arranged between adjacent bolt holes so that the notch depth can be reduced. It can be set arbitrarily within the range of the width of the inner peripheral portion, whereby the concentration of stress generated at the edge of the bolt hole can be largely suppressed.

(B) However, if the shape of the notch portion is simply made into a slit shape, stress concentration on the bottom of the notch becomes remarkable, and a crack may easily occur from the bottom of the notch.
Therefore, the notch is a notch comprising a slit and a notch bottom, and the width W1 of the notch bottom is changed to the width W of the slit.
The concentration of stress on the notch bottom is suppressed by using a single continuous curve that is larger than 2 and has no inflection point at the notch bottom as a contour line.

Here, the slit portion is a portion of a notch portion connecting the inner periphery of the brake disk and the notch bottom portion,
The width W2 of the slit portion is the length of a line segment connecting the notched bottom ends of the two contour lines of the slit portion.

The notch bottom portion is a portion of the notch portion having a line connecting the ends of the two contour lines of the slit portion on the notch bottom side as a contour line, the width W1 of the notch bottom portion and the width W1 of the notch bottom portion. Is the length of a line segment connecting both circumferential ends of the notch bottom.

A curve is a concept including a straight line.
The “one continuous curve having no inflection point”, which is the contour of the bottom of the notch, includes a curve and a straight line. (C) By setting the radius of curvature R of the notch bottom of the notch and the length L of the arc connecting the centers of the adjacent bolt holes to a shape satisfying the following expression (1), the notch bottom and the notch It is possible to suppress stress concentration at a position where the portion and the bolt hole are in close proximity.

Here, the notch bottom refers to a portion of the notch bottom located at the outermost side of the disk.

[0017]

(Equation 2) The present invention has been completed based on the above findings,
The summary is as follows.

(B) In a brake disk comprising an outer peripheral portion having a sliding surface and an inner peripheral portion having a bolt hole, the inner peripheral portion has a plurality of notches comprising a slit portion and a notch bottom portion, The width W1 of the notch bottom is larger than the width W2 of the slit portion, and the notch bottom has a contour as a continuous curve having no inflection point.

(B) The radius of curvature R of the notch bottom of the notch and the length L of an arc connecting the centers of adjacent bolt holes are:
The brake disc according to the above (1), wherein the following formula (1) is satisfied.

[0020]

(Equation 3) (C) the notch is located between adjacent bolt holes,
The brake disc according to the above (a) or (b), wherein the notch bottom portion is located in a range from the bolt hole to the inner peripheral portion outer end portion at a radial position of the brake disc.

Here, the "bolt hole" in the "range from the bolt hole to the outer end portion of the inner peripheral portion" means the innermost peripheral side when a plurality of rows of bolt holes having different positions in the disk radial direction are provided. Refers to the bolt hole located.

[0022]

FIG. 2 shows the shape of a brake disk according to an embodiment of the present invention. FIG. 2 (a) is a partial plan view showing a quarter of the brake disk, and FIG. FIG. 3 is an enlarged plan view of a cutout portion on the inner periphery of the brake disc of FIG. In the figure, the same elements as those in FIG. 1 are denoted by the same reference numerals.

As shown in FIGS. 1A and 1B, the brake disc 11 of the present invention includes a plurality of notches 1 formed on the inner peripheral portion 12 each including a slit portion 2 and a notch bottom portion 3. As described above, for example, in the conventional disk shown in FIG. 1, remarkable stress concentration occurs at the edge of the bolt hole on the inner peripheral portion of the disk due to the repeated thermal stress caused by braking. On the other hand, in the disc of the present invention, FIG.
As shown in (a) and (b), the provision of a plurality of notches 1 in the inner peripheral portion 12 of the disk 11 causes a new concentration of stress in the notches, but the stress on the edge of the bolt hole is increased. The stress concentration can be dispersed. Further, as a result, the outer peripheral portion 13
Is also reduced, so that the occurrence of thermal cracks on the sliding surface 15 of the outer peripheral portion 13 is also suppressed.

Further, since the notch 1 provided on the inner peripheral portion of the disk of the present invention has a slit shape including the slit 2 and the notch bottom 3, the strength of the edge of the bolt hole is not excessively impaired. The notch depth can be set arbitrarily within the range of the inner peripheral portion of the disk. As a result, stress concentration on the edge of the bolt hole can be significantly suppressed.

FIG. 3 shows the shape of a brake disk according to another embodiment of the present invention. FIG. 3 (a) is a partial plan view showing a quarter of the brake disk, and FIG.
It is the top view which expanded the notch part of the inner periphery of the brake disk of (a). 2, the same elements as those in FIG. 2 are indicated by the same reference numerals.

FIG. 4 is a graph showing the relationship between the notch depth D1 / D2 and the total strain at the edge of the bolt hole generated at the time of a brake load determined by FEM analysis. Here, as shown in FIG. 3, D1 is the distance in the radial direction of the disk from the inner peripheral end of the bolt hole to the notch bottom, and D2
Is the radial distance of the disc from the inner peripheral end of the bolt hole to the inner peripheral outer end. The notch depth D1 / D2 is a value obtained by dividing D1 by D2.

From the viewpoint of suppressing the concentration of stress on the edge of the bolt hole, as shown in FIG. 4, the more the notch depth is increased, the more the above-mentioned stress concentration can be suppressed. It is more preferable to be provided on the outer peripheral side as much as possible. Therefore, as shown in FIG. 3, it is preferable to provide the disk in a range from the bolt hole to the inner peripheral portion outer end portion at the radial position of the disk.

Various shapes can be applied to the shape of the notch of the brake disk of the present invention. 5A and 5B show a typical example of the shape of the notch. FIG. 5A shows a notch having a circular notch bottom, FIG. 5B shows an oval notch having a notch bottom, and FIG. FIG. 5C is a schematic view showing a cutout portion having a cutout bottom having an elliptical shape, and FIG. 5D is a cutout portion having a slit portion wider than FIG. 5A.

As shown in FIGS. 3A, 3B, 3C and 3D, the width W1 of the notch bottom 3 of the brake disk of the present invention is larger than the width W2 of the slit 2 and The notch bottom has a contour as a continuous curve having no inflection point. Thereby, stress concentration on the notch bottom can be suppressed.

If the radius of curvature R of the notch bottom 4 shown in FIGS. 1A, 1B, 1C, and 1D is too small, stress concentration on the notch bottom may become excessive. If it is too large, the concentration of stress at a position close to the bottom of the notch and the bolt hole may be excessive.

Therefore, it is preferable that the radius of curvature R of the notch bottom and the length L of the arc connecting the centers of the adjacent bolt holes determine a shape satisfying the following expression (1).

[0032]

(Equation 4) It is preferable that the number of the notch portions is four or more and twice or less 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 twice or less is that if too many notches are provided, it becomes difficult to keep the above-mentioned radius of curvature R of the notch bottom in an appropriate range.

Preferably, the notches are 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.

Further, in this embodiment, the brake disk having the notch in which the slit is linear has been described as an example. However, the position and shape of the slit do not excessively impair the strength of the edge of the bolt hole. If you have, linear,
Any shape such as a curved shape may be used.

In this embodiment, the brake disk for a railway vehicle has been described as an example. However, the present invention is not limited to this, and may be applied to a braking device for an automobile or a motorcycle.

[0036]

EXAMPLES In order to confirm the effects of the present invention, six types of disks (outer diameter: 725 mm) having different inner peripheral shapes by sand casting using an SiC particle-dispersed Al-based composite material.
Was manufactured and a brake test was performed. In addition, the strain at the edge of the bolt hole and the notch was obtained by FEM analysis.

Table 1 shows the shapes of the disks subjected to the test.

[0038]

[Table 1] For the six types of discs shown in Table 1, using a wheel tester modeled on a bogie of the JR Shinkansen, a pair of discs, wheels with the sliding surface (sliding surface width: 127.5 mm) outside And a brake test was performed. For the brake lining material, use a copper-based sintered alloy,
The conditions corresponded to emergency braking from a running speed of 300 km / h. At this time, about 100 seconds after the start of braking, the wheels stopped, and the disk temperature rose to about 350 ° C.
Thereafter, the disk was allowed to cool, and when the disk temperature dropped 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.

In the FEM analysis, the strain at the edge of the bolt hole and the notch after the first braking was obtained under the same conditions as the above-mentioned brake. Table 2 shows the results of the brake test,
Table 3 shows the results of the FEM analysis.

[0040]

[Table 2]

[0041]

[Table 3] In Table 2, "O" indicates that no crack was generated at the edge of the bolt hole and the notch after 100 times of the brake test, and "X" indicates that a crack was generated during the test.

As shown in Tables 2 and 3, the test material 4
Since the inner peripheral portion of the disk did not have a plurality of notches, stress concentration on the edge of the bolt hole could not be dispersed, and a crack was generated from the edge of the bolt hole in two brake tests.

The test material 5 has a plurality of notches formed of a slit and a notch bottom on the inner periphery of the disk. The width W1 of the notch bottom is larger than the width W2 of the slit, and the notch is notched. Since the bottom has a continuous curve having no inflection point as a contour line, stress concentration on the edge of the bolt hole can be dispersed. However, the ratio of the radius of curvature R of the notch bottom to the length L of the arc connecting the centers of the adjacent bolt holes (hereinafter, also referred to as R / L) is out of the preferred range and exceeds 3/10. The stress concentration was slightly large in the vicinity of the notch and the bolt hole, and a crack was generated from the notch after 15 times of the brake test.

The test material 6 is provided with a plurality of notches formed of a slit and a notch bottom on the inner periphery of the disk. The width W1 of the notch bottom is larger than the width W2 of the slit, and the notch is notched. Since the bottom has a continuous curve having no inflection point as a contour line, stress concentration on the edge of the bolt hole can be dispersed. However, since R / L is less than 1/10 of the appropriate range, the stress concentration on the notch bottom is slightly large,
In the five brake tests, a crack was generated from the notch.

Each of the test materials 1 to 3 is provided with a plurality of notches formed of a slit portion and a notch bottom portion on the inner peripheral portion of the disk.
The width W1 of the notch bottom is larger than the width W2 of the slit portion, and the notch bottom has a contour as a continuous curve having no inflection point, and an R / L of 1/10 or more and 3/10 or less. , Stress concentration on the edge of the bolt hole and the bottom of the notch was significantly suppressed, and the crack was not generated on both the edge of the bolt hole and the notch.

[0046]

According to the present invention, it is possible to effectively suppress the concentration of stress on the edge of the bolt hole due to the thermal stress generated during braking and to suppress the occurrence of cracks from the edge of the bolt hole of the disk. It is possible to obtain a brake disc that can withstand use for a period.

[Brief description of the drawings]

FIG. 1 is a diagram showing the shape of a conventional railway vehicle brake disc, FIG. 1 (a) is a partial plan view showing a quarter of a railway vehicle brake disk, and FIG. It is a partial sectional view showing 1/2 of a section of a brake disc for vehicles.

FIG. 2 is a view showing an embodiment of a brake disk according to the present invention. FIG. 2 (a) is a partial plan view showing a quarter of the brake disk, and FIG. 2 (b) is a brake shown in FIG. 2 (a). FIG. 4 is an enlarged plan view of a notch on the inner periphery of the disk.

FIG. 3 is a view showing another embodiment of the brake disk of the present invention, wherein FIG. 3 (a) is a partial plan view showing a quarter of the brake disk, and FIG. 3 (b) is a view of FIG. 3 (a). It is the top view which expanded the notch part of the inner periphery of a brake disc.

FIG. 4 shows the total strain and notch depth D1 / D2 of a bolt hole edge generated at the time of a brake load determined by FEM analysis.
6 is a graph showing a relationship with the graph.

FIG. 5 is a schematic view showing a typical example of a notch shape, and FIG.
5A is a cutout having a circular notch bottom portion, FIG. 5B is a cutout portion having an oval cutout bottom, FIG. 5C is a cutout portion having an oval cutout bottom, FIG. 5D is a schematic view showing a notch having a slit wider than that of FIG. 5A.

[Explanation of symbols]

1: Notch part 2: Slit part 3: Notch bottom part 11: Brake disk 12: Inner peripheral part 13: Outer peripheral part 14: Bolt hole 15: Sliding surface

Continued on the front page (72) Inventor Taizo Makino 4-33, Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Inside Sumitomo Metal Industries Co., Ltd. (72) Inventor Yasuhisa Misawa 5-1-1109, Shimaya, Konohana-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries Co., Ltd. Kansai Works Rental products In-house F-term (reference) 3J058 BA44 BA46 CB14 CB17 FA21

Claims (3)

[Claims] 1. A brake disc comprising an outer peripheral portion having a sliding surface and an inner peripheral portion having a bolt hole, wherein the inner peripheral portion has a plurality of notches comprising a slit portion and a notch bottom portion, A brake disk, wherein a width W1 of a notch bottom is larger than a width W2 of the slit portion, and the notch bottom has a contour as a continuous curve having no inflection point. 2. A radius of curvature R of a notch bottom of the notch bottom.
2. The brake disk according to claim 1, wherein the length of the arc connecting the centers of the adjacent bolt holes satisfies the following expression (1). 3. (Equation 1) 3. The notch portion is located between adjacent bolt holes, and the notch bottom portion is located in a radial position of the brake disc in a range from the bolt hole to an inner peripheral outer end. The brake disc according to claim 1 or 2, wherein