JP2000154837A - Brake disk for railcar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life of a disk, and decrease a load to a fastening bolt by providing a groove in a circumferential direction on a sliding surface of a brake disk fastened on side surfaces of wheels to suppress deformation. SOLUTION: Grooves 11 in a circumferential direction, for instance, three grooves, are provided on a sliding surface 4 of a disk 3 in which the severest thermal load stress is added to generate thermal stress. By grooves 11 provided on the sliding surface 11, the thermal stress in a radial direction generated on the sliding surface is relaxed, and then deformation to the anti-wheel side of the disk is suppressed. The grooves can be provided over whole circumference, and can be partially intermitted by forming parts, which have a part without a groove. It is desirable to apply two to ten grooves as the number of the grooves 11, 1 to 5 mm as width of the groove, and 2 to 7 mm as depth of the groove. Since a thickness, an inner diameter of the sliding surface, and an outer diameter of the sliding surface of a brake disk for a railcar are about 10 to 20 mm, about 200 to 400 mm, and about 600 to 900 mm, respectively; there is no problem on strength of the disk even if such grooves are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake disk provided on a side surface of a wheel for a railway vehicle.

[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. 2. Description of the Related Art In recent years, disk brakes have been frequently used as vehicles have become faster and larger. The disc brake has a structure in which a braking force is obtained by friction between a brake disc and a brake lining, and is usually attached to an axle or a wheel by bolts.

[0003] Examples of brake disks used in railway vehicles include side disks and shaft mount disks. 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. The present invention relates to a side disk, and hereinafter, a brake disk (disk) refers to a side disk.

FIG. 1 is a partial cross-sectional view of a railway wheel equipped with a brake disk. In the figure, reference numeral 1 denotes a wheel, 2 denotes an axle, 3 denotes a disc brake disc, 4 denotes a sliding surface, 5 denotes a rim, 6 denotes a wheel disc, 7 denotes a wheel bolt hole, 8 denotes a disc bolt hole, 9 Is a bolt for fastening the disk to the wheel, and 10 is a nut.

[0005] The sliding surface 4 of the disk 3 is on one side and generates heat, so that a strain is applied in a direction in which the sliding surface 4 side extends, that is, a direction in which the sliding surface 4 is curved in a direction opposite to the sliding surface.
However, since the non-sliding surface side is restrained by the wheel disk 6, compressive thermal stress is accumulated on the sliding surface 4 side, particularly at a portion where the brake pad is in contact, and when the stress exceeds the yield stress of the material, plastic strain is generated. Occurs. When the brake is released, the temperature of the disk 3 decreases, and expansion due to heat is stopped. However, since the disk 3 has yielded to the compression side, the sliding surface 4 contracts, and as shown by the dotted line in FIG. Deforms into a mortar shape on the side (warpage occurs).

Next, when the brake is applied, the sliding surface 4 becomes high in temperature, and the temperature on the side opposite to the sliding surface of the disk does not rise. , And compressive thermal stress is accumulated on the sliding surface side. When the brake is released, the disk 3 is further deformed toward the sliding surface 4 as described above. As described above, the thermal stress is repeatedly applied, and the plastic strain is generated, so that the plastic deformation of the disk 3 increases.

When the disk warps, uneven wear occurs between the disk and the lining, and the friction characteristics become unstable. Also, due to the deformation of the disk, a bending moment acts in the axial direction of the disk when a brake is applied, and a bending / tensile stress is generated in the bolt 9, and the maximum to minimum stress fluctuates according to the rotation of the wheel. 9 shortens the service life and may cause bolt damage.

In order to prevent warpage, a method of providing a bolt hole on the outer peripheral side of the disk 3 and the wheel disk 6 and fastening with a bolt is considered. However, if a bolt hole is provided in the outer peripheral portion of the wheel disk 6, particularly near the rim 5, the bolt hole may be cut out and stress concentration may occur, so that the wheel needs to be thickened. This measure is undesirable because of the increased weight and the need to significantly change the shape of the wheels.

In a high-speed railway vehicle such as a Shinkansen, the rotational speed and inertia force when a brake is applied are extremely large, so that the temperature rise of the disk is remarkably large as compared with those of other automobiles and motorcycles. Therefore, the thermal strain accompanying the temperature rise also becomes very large. Further, the deformation of the disk caused by the repeated application of the thermal strain increases.

In order to suppress the above deformation, for example, Japanese Patent Application Laid-Open No. 9-250577 discloses that a disk is divided into three parts in a circumferential direction, a gap is provided between each disk, and a mortar-like deformation of the integrated disk is performed. There is disclosed a technique for avoiding the above problem and alleviating the bending stress applied to the bolt.

However, although this technique has the effect of reducing the distortion of the disk alone, there is a problem in that the sliding surface is divided by dividing the disk, and the friction characteristics and wear characteristics are deteriorated. Also, the radial strain has not been alleviated.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to prolong the life of a disk by suppressing the deformation of the disk.
An object of the present invention is to provide a brake disk for a railway vehicle in which the load on a bolt for fastening a disk and a wheel is reduced to improve the durability of the bolt.

[0013]

Means for Solving the Problems The present inventors have studied various measures against the warpage and obtained the following knowledge. (a) In a brake disk fastened to the side surface of a wheel, the severest thermal load is applied to the sliding surface, and the resulting thermal stress is applied. Since the disc is restrained on the side opposite to the sliding surface,
If the thermal stress is not relieved and the yield stress is exceeded, plastic deformation occurs on the disk sliding surface, and when the brake is released, the sliding surface contracts and warps. If the thermal stress in the radial direction is reduced or released, no warpage occurs.

(B) If a portion where the thermal stress exceeds the yield stress on the sliding surface of the disk is divided, the stress is relieved. That is, a groove or a slit may be formed. Although the grooves or slits can reduce the thermal stress when inserted in the radial direction, the circumferential direction, or in both directions, it is effective to set the direction of the grooves and slits in the circumferential direction to prevent warpage. In this case, if the slit is formed through the disk, the disk is decomposed, so that the groove is preferably used.

(C) If the depth of the groove is in a range where the thermal stress exceeds the yield stress, plastic deformation can be prevented. If the groove is too deep, the disk strength will decrease. Further, if the width of the groove is too large or the number of the grooves is increased, the number of sliding surfaces contributing to friction is reduced.

The gist of the present invention completed on the basis of the above findings is as described in the following (1) and (2). (1) A brake disk for a railway vehicle, wherein the brake disk is fastened to a side surface of a wheel and has a circumferential groove on a sliding surface. (2) The brake disk for a railway vehicle according to claim 1, wherein the number of grooves is 2 to 10, the groove width is 1 to 5 mm, and the groove depth is 2 to 7 mm.

[0017]

FIG. 2 is a schematic view showing an example of a brake disk according to the present invention. FIG. 2 (a) is a front view of a 1/4 portion, and FIG. 2 (b) is an A view of FIG. It is -A sectional drawing. As shown in the figure, the disk 3 of the present invention is provided with a circumferential groove 11 on the sliding surface 4. In the illustrated example, three grooves are provided. The grooves 11 provided on the sliding surface 4 alleviate the thermal stress in the sliding surface in the radial direction, thereby suppressing the deformation of the disk toward the wheel. In the example shown in FIG. 2, the groove is provided over the entire circumference,
The groove may be partially interrupted. However, if the total of the intermittent portions (portions without grooves) exceeds 20% of the circumference, the thermal stress, which is the object of the present invention, cannot be reduced.

FIG. 3 is a sectional view showing the shape of a groove provided on the disk sliding surface of the present invention. The number of grooves 11 provided on the sliding surface is preferably in the range of 2 to 10. If it exceeds 10, the contact area between the disk and the lining becomes small and the friction characteristics deteriorate, and if it is less than 2, the effect of relaxing the thermal stress decreases. From the viewpoint of the balance between the deformation suppressing effect and the stability of the frictional characteristics, it is more preferable to use 2 to 5 wires.

The groove width W is preferably in the range of 1 to 5 mm. When W exceeds 5 mm, the contact area with the lining becomes small, and the braking force decreases. When W is less than 1 mm, machining is difficult. More preferably, it is good to make it into the range of 2-3 mm.

The groove depth D is preferably in the range of 2 to 7 mm. If the groove depth is less than 2 mm, the range in which the thermal stress exceeds the yield stress is deeper, the effect of suppressing deformation is reduced, and the groove may be lost due to wear of the disk. If the groove depth exceeds 7 mm, the disk strength decreases and stress concentrates on the bottom of the groove. More preferably, it is good to make it into the range of 3-5 mm. Further, in order to suppress stress concentration, it is preferable that the groove edge 12 be rounded or chamfered, and the groove bottom 13 be rounded.

The thickness of a railway brake disc is usually 10
Approximately 20 mm (30 to 50 mm including the fins when cooling fins are provided on the back surface), the inner diameter of the sliding surface (the portion to be hit by the brake pad) is 200 to 400 mm, and the outer diameter is approximately 600 to 900 mm. Therefore, even if the grooves are provided, there is no problem on the strength of the disk.

[0022]

EXAMPLES Table 1 shows a list of brake disk samples 1 to 7 subjected to a brake test. As the disk material, a forged steel disk material widely used in Shinkansen vehicles at present is used. The thickness of the disk was 16 mm, the inner diameter of the sliding surface was 295 mm, and the outer diameter was 780 mm.

[0023]

[Table 1]

Sample 1 corresponds to an example of the present invention. As shown in FIG. 2, the number of grooves is three, the groove width is 2 mm, and the groove depth is 3 m.
The groove edge was chamfered 1 mm (C1) and the groove bottom was rounded 2 mm (R2).

As another example of the present invention, the number of grooves, the width, and the depth of samples 2 to 5 were changed. As a conventional disc,
A method of dividing a disk into three parts (hereinafter, referred to as a sample 6) as in the technique disclosed in JP-A-9-250577;
One conventional disk with no groove (hereinafter referred to as Sample 7)
) Was prototyped.

In the sample 6, the gap width in the radial direction of the disk divided into three was set to 2 mm. The outer diameter of the disk, the width of the sliding surface, the material, and the like were the same in both the present invention example and the conventional example.

A body brake test was performed using the above seven types of disks. The brake test conditions were an emergency brake starting from 300 km / h, where the load on the disc was severe. When emergency braking is applied from 300km / h, about 1
Stop at 00 seconds. At this time, the disk temperature rises up to about 600 ° C. After the brake load, the system was cooled to 50 ° C. or less, and the brake load test was performed again. This brake load was repeated 100 times. Table 2 shows the results of the brake test.

[0028]

[Table 2]

In sample 4, the test was interrupted because a crack was generated from the bottom of the groove at 68 brake loads. With respect to samples other than the sample 4, the amount of deformation of the disk after 100 times of the brake load was compared. The amount of deformation of the disk was the amount of warpage at the outermost periphery of the disk with the disk fixing bolts fastened.

Sample 7 of the prior art had the largest deformation. Sample 3 of the present invention had less than half the amount of deformation of sample 7, and samples 1, 2, 5, and 6 of the present invention had a smaller and sufficient deformation suppressing effect.

Next, friction characteristics, which are important characteristics as a brake disk, were compared. From Table 2, the average friction coefficient is lower in Samples 2 and 4 of the present invention. This is sample 2
It is considered that the reason is that the contact area between the disk and the lining is small because the groove width is large and the number of grooves in sample 6 is large. The average friction coefficient of the other disks was almost the same.

The variation range of the coefficient of friction is larger in Samples 2, 5, and 6. As described above, in Samples 2 and 5, it is considered that the contact area between the disk and the lining is small. In the sample 6 of the conventional example, since the sliding surface is divided in the circumferential direction, a step is formed in the circumferential direction, and it is considered that the fluctuation range of the friction coefficient is large.

Further, the axial force of the bolt was measured. An average stress and a repeated stress (stress amplitude) are applied to the bolt, but the bolt undergoes fatigue failure due to the repeatedly generated tensile stress. The average stress is a tensile stress generated when a bolt is fastened. In general, the higher the average stress, the lower the fatigue limit. When the stress amplitude is large, it causes fatigue fracture. The bolts that fasten the brake disc include stress that restrains the thermal expansion of the disc, stress caused by the warpage of the disc being restored to its original shape when the lining is pressed, and stress caused by torque when the brake is loaded.
A repetitive stress is applied with the brake load.

In the seven types of disks subjected to the actual brake test, there was no difference in the value of the average stress of the bolts, and the values were almost the same. On the other hand, comparing the stress amplitude of bolts,
Samples 3 and 7 are the largest. From the above, it was found that the larger the amount of warpage of the disk, the larger the stress amplitude applied to the bolt.

From the results of the above-mentioned brake test, the use of the disk of the present invention can suppress the deformation (warpage) of the disk without impairing the frictional characteristics as compared with the conventional disk, and further reduce the fatigue fracture of the bolt. It became clear that it could be avoided.

[0036]

According to the brake disk of the present invention, deformation (warpage) of the disk can be suppressed, and the life of the disk and the bolt can be further extended. In addition, the maintenance cost is reduced by reducing the number of bolts to the same level of durability as the conventional one.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a railway wheel equipped with a brake disk.

FIG. 2 is a schematic view showing a quarter front view and a cross section of a brake disc of the present invention.

FIG. 3 is a sectional view showing a shape of a groove provided on a disk sliding surface of the present invention.

[Explanation of symbols]

 Reference Signs List 1 wheel 2 axle 3 disk 4 sliding surface 5 rim 6 wheel disk 7 wheel bolt hole 8 disk bolt hole 9 bolt 10 nut 11 groove 12 groove edge 13 groove bottom W groove width D groove depth

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Miyuki Yamamoto 4-33 Kitahama, Chuo-ku, Osaka City F-term in Sumitomo Metal Industries, Ltd. 3J058 AA44 AA47 AA53 AA87 BA32 CB17 CB29 FA21

Claims (2)

[Claims] 1. A brake disk for a railway vehicle, wherein the brake disk is fastened to a side surface of a wheel and has a circumferential groove on a sliding surface. 2. The number of grooves is 2 to 10 and the groove width is 1 to 5 m.
The brake disc for a railway vehicle according to claim 1, wherein m and a groove depth are 2 to 7 mm.