JP2010270802A - Brake disc - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a structure without causing damage such as a crack at the inner peripheral edge of a surface layer 3b formed of an aluminum alloy group composite material. <P>SOLUTION: An inner peripheral edge shape of the surface layer 3b is formed in a composite circular arc shape formed by continuing first and second partial circular arcs 7 and 8 different in a radius of curvature. A central position in the circumferential direction of the respective first partial circular arcs 7 and 7 large in the radius of curvature and a central position in the circumferential direction of respective cutouts 4 and 4 are made to coincide with each other. A central position in the circumferential direction of the respective second partial circular arcs 8 and 8 small in the radius of curvature and a central position in the circumferential direction of respective installation parts 5 and 5 are also made to coincide with each other. Mutual ends of these respective first and second circular arcs 7 and 8 are also smoothly continued. By this, tensile stress and thermal stress generated in a part adjacent to the innermost side parts 9 and 9 of the respective cutouts 4 and 4 among the inner peripheral edge of the surface layer part 3b are reduced at braking. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an improvement in a brake disk constituting a braking device in a general railway vehicle including a high-speed railway vehicle such as a bullet train and a conventional line.

  As a brake disk for a high-speed railway vehicle, conventionally, for example, as described in Patent Documents 1 to 3, an axial side surface portion of an outer diameter portion that rubs against a brake pad is made of ceramic particles and fibers. A composite structure made of a composite material including at least one of the above is considered. Since such a composite type brake disc can be reduced in weight while ensuring wear resistance (durability), in recent years, it has been studied to use it in place of a cast iron brake disc. 5 to 6 show a conventional structure described in Patent Document 1 among such a composite brake disc 1.

The brake disk 1 includes an aluminum alloy main body 2 and an aluminum alloy as a matrix material, ceramic particles such as silicon carbide (SiC) and alumina (Al ₂ O ₃ ), fibers, or both (these And a surface layer portion 3 made of an aluminum alloy matrix composite in which the same is applied throughout the present specification and claims), and has a ring shape as a whole. In the case of the manufacturing method described in Patent Document 1 in order to manufacture such a brake disc 1, an annular material to be the surface layer portion 3 is previously formed of an aluminum alloy matrix composite material and an intermediate material. To do. The intermediate material is placed in a cavity for casting the main body 2 (including die-cast molding. The same applies throughout the present specification and claims), and an aluminum alloy is placed in the cavity. Feed the molten metal. Alternatively, as described in Patent Documents 2 and 3, there is a case where a ceramic material formed into an annular shape is placed in a cavity and then the molten metal is fed into the cavity.

  Conventionally known composite brake discs are manufactured by any manufacturing method, and the shape of the surface layer portion 3 is a circular shape that is concentric with each other on both the inner and outer peripheral edges. On the other hand, with respect to the shape of the portion close to the inner diameter of the main body 2, the shape described in Patent Documents 2 and 3 shown in FIG. 7 and the shape described in Patent Document 1 shown in FIG. This is advantageous both from the viewpoint of reducing thermal stress and from the viewpoint of weight reduction. A plurality of notch portions 4 and 4 and attachment portions 5 and 5 are alternately arranged in the circumferential direction on the inner peripheral edge portion of the main body portion 2a of the brake disc 1a described in Patent Documents 2 and 3, respectively. is doing. Each of the cutouts 4 and 4 has a purse shape in which the radius of curvature at the back is large, the radius of curvature at both sides is small, and the width of the opening is narrow. The mounting portions 5 and 5 are formed with through holes 6 and 6 for inserting bolts (not shown) described below.

  When the brake disc 1a having the shape shown in FIG. 7 is used, the wheels (not shown) of the railway vehicle are sandwiched from both sides in the axial direction by the pair of brake discs 1a. In this state, the bolts and nuts inserted into the through holes 6 and 6 formed in the brake discs 1a and the through holes formed in the wheels are screwed and further tightened, whereby The brake discs 1a are fixed on both sides in the axial direction. In the case of the second example of the conventional structure shown in FIG. 7, in addition to reducing the thermal stress generated in the portion near the inner diameter by forming the notches 4, 4, the notches Since the portions 4 and 4 are formed, the brake disc 1a can be reduced in weight. However, since the distance between the rear side portions 9 and 9 of each of the cutout portions 4 and 4 and the inner peripheral edge of the surface layer portion 3a is reduced, it is disadvantageous from the viewpoint of ensuring durability. This point will be described below.

  During braking, the pad lining is pressed against the surface layer portion 3a of the brake disc 1a, and braking is performed by friction between the surface layer portion 3a and the lining. The brake torque applied to the brake disc 1a with this braking is transmitted to the wheels via the mounting portions 5 and 5 and the bolts. A great force is applied in the direction. Based on this force, a large tensile stress is generated at the peripheral portions of the notches 4 and 4, particularly at the back side portions 9 and 9 of the notches 4 and 4. Is also added to the inner peripheral edge portion of the surface layer portion 3a. Further, the temperature of the surface layer portion 3a that rubs against the lining during braking increases significantly, whereas the temperature increase in the portion near the inner diameter where there is no friction is limited. As a result, a large temperature difference occurs between the outer diameter side portion and the inner diameter side portion of the brake disc 1a. Since the thermally expanded outer diameter side portion pulls the inner diameter side portion, a large thermal stress is generated as a tensile stress in each of the inner side portions 9 and 9. The magnitude of this tensile stress is still a large value even if it is kept lower than the value of the portion where the tensile stress is greatest when the notches 4 and 4 are not formed. Since the surface layer portion 3a is made of an aluminum alloy-based composite material, which is a material that is less viscous (less tough) than a simple aluminum alloy, damage such as cracks is likely to occur based on the tensile stress.

  In view of the circumstances as described above, the present invention is advantageous in terms of reducing thermal stress and reducing weight, and a plurality of notches 4 and 4 and mounting portions 5 and 5 are provided on the inner peripheral edge of the main body 2a. Are invented in order to realize a structure in which damage such as cracks is unlikely to occur in the surface layer portion 3a made of an aluminum alloy matrix composite material.

The brake disc of the present invention has a friction surface on the axial side surface near the outer diameter, as in the conventional brake discs described in Patent Documents 2 and 3, and the inner peripheral edge portion. A plurality of notches and attachments are alternately arranged in the circumferential direction.
The friction surface portion is constituted by a surface layer portion made of an aluminum alloy matrix composite material in which a ceramic material is dispersed in an aluminum alloy, and portions other than the friction surface are made of an aluminum alloy.

  In particular, in the brake disc of the present invention, the inner peripheral edge shape of the surface layer portion is a composite arc shape in which a plurality of types of partial arcs having different curvature radii are continuous. And the curvature radius of the part in which the phase regarding the circumferential direction corresponds to each said notch part is made larger than the curvature radius of the part which similarly corresponds to each said attachment part.

According to the present invention configured as described above, it is possible to realize a brake disk that can reduce thermal stress, is lightweight, and can secure sufficient durability.
That is, the thermal stress is applied as a tensile stress to the backside of each notch during braking by the mechanism described above, but in the inner periphery of the surface layer part with low toughness, the backside of each notch Since the radius of curvature of the adjacent portion is large, the tensile stress applied to the inner peripheral edge can be kept low. For this reason, it is difficult to cause damage such as cracks in the surface layer portion, and the durability of the brake disk including the surface layer portion can be sufficiently ensured.

The perspective view which shows one example of embodiment of this invention. The upper left enlarged view of FIG. The orthographic projection seen from the outer surface side which installed the surface layer part. The upper right part enlarged view of FIG. The partial orthographic view which shows the 1st example of a prior art structure. Sectional drawing seen from the bottom of FIG. The half orthographic view which shows the 2nd example of a conventional structure.

  1 to 4 show a first embodiment of the present invention. The brake disc 1b of the present embodiment is similar to the brake disc 1a (FIG. 7) described in Patent Documents 2 and 3 described above, and a body portion 2b made of an aluminum alloy and an aluminum alloy-based composite. It has a surface layer portion 3b made of material, and has a ring shape as a whole. Further, six cutout portions 4, 4 and attachment portions 5, 5 are alternately arranged in the circumferential direction on the inner peripheral edge portion of the main body portion 2b. Each of the cutouts 4 and 4 has a purse shape in which the radius of curvature at the back is large, the radius of curvature at both sides is small, and the width of the opening is narrow. The mounting portions 5 and 5 are formed with through holes 6 and 6 for inserting bolts, respectively. A stepped portion 10 is formed in a portion of the main body 2b that circumscribes the notches 4 and 4. The height of the side surface portion of the brake disc 1b where the surface layer portion 3b is provided is higher on the outer diameter side than the inner diameter side of the stepped portion 10.

In particular, in the case of the brake disc 1b of this example, the shape of the inner peripheral edge of the surface layer portion 3b is such that the regular hexagon is inflated to the outer diameter side, and each side and each corner are convex arcs. . That is, the inner peripheral edge of the surface layer portion 3b is divided into two kinds of partial arcs having different curvature radii, that is, first partial arcs 7 and 7 having a large curvature radius and second partial arcs 8 and 8 having a small curvature radius. Are formed in a composite arc shape, which is alternately and continuously in the circumferential direction. Of these, the radius of curvature of the first partial arcs 7 and 7 is as long as the surface area of the surface layer portion 3b (the friction area of the pad lining) can be secured, in other words, the top of each of the second partial arcs 8 and 8. position of, within a range not biased overly the outer diameter side in the radial direction of the brake disc 1b (range that can ensure the minimum width W _min of the surface layer portion 3b), as large as possible.

  On the other hand, the minimum value of the radius of curvature of each of the second partial arcs 8 and 8 is not particularly limited, but the circumferential end of each of the first arcs 7 and 7 and each of the cutouts 4 and 4 It is preferable to make it as large as possible within a range in which the distance from the rear side portions 9 and 9 can be secured. It should be noted that securing the distance between the circumferential ends of the first arcs 7 and 7 and the back sides 9 and 9 of the notches 4 and 4 is to ensure that the notches 4 and 4 are at the time of braking. 4 is necessary to stop the tensile stress generated in the back side portions 9 and 9 within the range of the first arcs 7 and 7 having a large curvature radius. In other words, this is to prevent the tensile stress from affecting the second arcs 8 and 8 having a small radius of curvature. Further, the volume of the aluminum alloy main body 2b existing on the inner diameter side of each of these second partial arc portions 8 and 8 is secured, and the heat of each of these second partial arc portions 8 and 8 can be easily released. It is important to secure the distance also from the aspect of carrying out.

  As shown in the figure, the surface layer portion 3b and the main body portion 2b are arranged at the center position in the circumferential direction of the first partial arcs 7 and 7 having a large radius of curvature and the circles of the notch portions 4 and 4, respectively. The circumferential center position is made to coincide with each other, and the circumferential center position of the second partial arcs 8 and 8 having a small radius of curvature is made to coincide with the circumferential center position of each of the mounting parts 5 and 5. Combined in the state. And the edge parts of said 1st, 2nd circular arcs 7 and 8 are made to continue smoothly. Of the main body 2b, a portion located on the outer diameter side of each of the mounting portions 5 and 5 and on the outer diameter side of the stepped portion 10 is on the same plane as the surface layer portion 3b. .

According to the structure of the present example configured as described above, it is possible to realize the brake disk 1b that can reduce thermal stress, is lightweight, and can secure sufficient durability.
That is, thermal stress is applied as tensile stress to the rear side portions 9 and 9 of the notches 4 and 4 during braking by the mechanism described above. Then, based on the tensile stress, the portions adjacent to the back side portions 9 and 9 among the back side portions 9 and 9 and the inner peripheral edge portion of the surface layer portion 3b are linearly stretched. Or tend to expand in the circumferential direction due to thermal expansion. In contrast to this tendency, in the case of the structure of this embodiment, the portion of the inner peripheral edge portion of the surface layer portion 3b that is close to the rear edge portions 9 and 9 of the cutout portions 4 and 4 is used. Are the first arcs 7 and 7 having a large curvature radius. When a force in the pulling direction is applied to the arc-shaped portion, the tensile stress generated in the portion increases as the curvature radius of the portion decreases. In the case of the present embodiment, since the portions adjacent to the respective back side portions 9 and 9 are the respective first arcs 7 and 7, the tensile stress applied to the inner peripheral edge portion can be kept low. For this reason, damage such as cracks is unlikely to occur in the surface layer portion 3b, and the durability of the brake disk 1b including the surface layer portion 3b can be sufficiently ensured. Note that, as described in Patent Document 3, for example, increasing the thickness of the surface layer portion 3b toward the outer diameter side further relaxes the thermal stress applied to the inner peripheral edge portion of the surface layer portion 3b. Is preferable.

In carrying out the present invention, the method for joining the surface layer portion made of an aluminum alloy matrix composite and the main body portion made of an aluminum alloy is not particularly limited. As described in the above-mentioned Patent Document 1, a surface layer portion that has been processed in advance may be combined with the main body portion when casting the main body portion, or described in the above-mentioned Patent Documents 2 and 3. As described above, a surface layer portion made of an aluminum alloy matrix composite material can be made simultaneously with the casting of the main body portion.
Moreover, the shape of the surface (inner side surface in which the surface layer part is not provided) which opposes the side surface of a wheel among the axial direction both sides | surfaces of a brake disc is not ask | required especially. Generally, as described in Patent Documents 2 and 3, it is preferable to form a large number of fins radially.

DESCRIPTION OF SYMBOLS 1, 1a, 1b Brake disc 2, 2a, 2b Main body part 3, 3a, 3b Surface layer part 4 Notch part 5 Mounting part 6 Through-hole 7 1st partial arc 8 2nd partial arc 9 Back part 10 Step part

JP-A-9-53669 JP 2006-328474 A JP 2006-329316 A

Claims (2)

  The axial side surface near the outer diameter is a friction surface, and a plurality of notches and mounting portions are alternately arranged in the circumferential direction on the inner peripheral edge. The ceramic material is placed in an aluminum alloy. In the brake disk in which the friction surface portion is constituted by the surface layer portion made of the aluminum alloy matrix composite material dispersed, and the portion other than the friction surface is made of aluminum alloy, the inner peripheral shape of the surface layer portion has a curvature. It is a composite arc shape in which a plurality of types of partial arcs having different radii are continuous, and the curvature radius of the portion where the phase in the circumferential direction coincides with each notch is the same as the curvature of the portion that coincides with each mounting portion. Brake disc characterized by being larger than the radius.   There are two types of curvature radii of the partial arcs, and the number of each partial arc is the same as the number of the cutout portions and the attachment portions, and the central portion in the circumferential direction of the first partial arc having a large curvature radius. The circumferential center position of the second partial arc having a small curvature radius and the circumferential central position of each mounting portion are the same as each other and the circumferential central position of each notch. The brake disc according to claim 1, wherein the brake discs are coincident with each other and the ends of the first and second arcs are smoothly continuous.

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