JP2016142316A - Disc brake and method of manufacturing piston - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disc brake and a method of manufacturing a piston, which can improve manufacturing efficiency.SOLUTION: A disc brake comprises a piston 21 that is arranged movably in a cylinder hole of a caliper body and is formed having a cylindrical part 41 and a partition wall 43 closing an inner hole 42 of the cylindrical part 41. In the cylindrical part 41, a boot groove 51 and a seal groove 52 are formed by spinning to put the partition wall 43 between them in the axial direction of a disc rotor. The boot groove is annularly provided on one end side of the outer periphery of the cylindrical part 41 along the circumferential direction of the cylindrical part 41, and an end of a piston boot is fitted in the boot groove. The seal groove is annularly provided on the other end side of the outer periphery of the cylindrical part 41 along the circumferential direction of the cylindrical part 41, and a seal member is received in the seal groove.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a disc brake and a method for manufacturing a piston.

  There is a disc brake in which a seal groove is provided on the cylinder bottom side of a piston (see, for example, Patent Document 1).

JP 2012-2250 A

  In order to improve the manufacturing efficiency of the disc brake, it is desired to improve the manufacturing efficiency of the piston.

  An object of the present invention is to provide a disc brake and a piston manufacturing method capable of improving manufacturing efficiency.

  In order to achieve the above object, a disc brake of the present invention includes a piston that is movably disposed in a cylinder hole of a caliper body and has a cylindrical portion and a partition wall that closes the inner hole of the cylindrical portion. The cylindrical portion is provided annularly on one end side of the outer periphery of the cylindrical portion along the circumferential direction of the cylindrical portion, the boot groove into which the end of the piston boot is fitted, and the outer periphery of the cylindrical portion A seal groove provided annularly along the circumferential direction of the cylindrical portion on the end side and accommodating a seal member is formed by spinning so as to sandwich the partition wall in the axial direction of the disk rotor.

  In the piston manufacturing method of the present invention, the piston is formed by forming a piston material having a cylindrical portion having an outer diameter smaller than the cylinder hole, and a partition wall closing the inner hole of the cylindrical portion, and the cylindrical portion. At least two annular grooves along the circumferential direction of the cylindrical portion are formed by pressing the outer periphery of the cylindrical portion and plastically deforming at a position sandwiching the partition wall on the outer periphery of the cylindrical portion.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the disc brake and piston which can improve manufacturing efficiency can be provided.

Sectional drawing which shows the disc brake of embodiment. In embodiment, the partial side view which shows the spinning process apparatus of the state in which the piston set in the spinning process apparatus and the piston were set. In embodiment, the partial side view which shows the spinning processing apparatus of the state which supported the piston of the state which supported the axial direction both sides with the spinning processing apparatus, and a piston. In embodiment, the partial side view which shows the spinning process apparatus of the state which is spinning the piston and piston during spinning process with a spinning process apparatus. In embodiment, the partial side view which shows the spinning processing apparatus of the state after spinning the piston after a spinning process and the piston by the spinning process apparatus.

  An embodiment according to the present invention will be described below with reference to the drawings. The disc brake 10 according to the embodiment is for a vehicle such as an automobile, specifically for a four-wheeled vehicle. A disc brake 10 shown in FIG. 1 brakes a vehicle by stopping the rotation of a disc rotor 11 that rotates with a wheel (not shown).

  The disc brake 10 includes a carrier 12, a pair of brake pads 13 and 14, and a caliper 15. The carrier 12 is disposed across the outer peripheral side of the disk rotor 11 and is fixed to the non-rotating portion of the vehicle. The pair of brake pads 13, 14 are supported by the carrier 12 and disposed opposite to both surfaces of the disk rotor 11. The caliper 15 sandwiches the pair of brake pads 13 and 14 and presses them on both sides of the disc rotor 11.

  The caliper 15 includes a caliper main body 20, a piston 21, a seal member 22, and a piston boot 23. The piston 21 is slidably provided on the inner side (in the vehicle width direction) of the caliper body 20. The seal member 22 seals the gap between the caliper body 20 and the piston 21. The piston boot 23 is connected to the caliper body 20 and the piston 21 and covers a part of the piston 21 exposed from the caliper body 20.

  The caliper body 20 has a cylinder 26, a bridge portion 27, and a claw portion 28. The cylinder 26 faces the surface of the disk rotor 11 on one side in the axial direction. The bridge portion 27 extends from the cylinder 26 so as to straddle the outer periphery of the disk rotor 11. The claw portion 28 extends from the opposite side of the bridge portion 27 to the cylinder 26 and faces the other surface of the disk rotor 11 in the axial direction. A cylinder hole 30 that opens toward the disc rotor 11 in the axial direction of the disc rotor 11 is formed in the cylinder 26. As described above, the caliper body 20 is provided so as to straddle the outer periphery of the disk rotor 11 and has a shape having the cylinder hole 30 that opens toward the disk rotor 11 in the axial direction of the disk rotor 11. A piston 21 is movably disposed in the cylinder hole 30.

  By forming the cylinder hole 30, the cylinder 26 has a bottom 31 disposed on the opposite side of the disk rotor 11 in the axial direction of the disk rotor 11 and a cylindrical shape from the outer peripheral edge of the bottom 31. 11 and a cylindrical portion 32 extending toward the disk rotor 11 in the axial direction. An annular boot support groove 34 is formed on the inner peripheral surface of the cylindrical portion 32 opposite to the bottom portion 31 on the opening 33 side of the cylinder hole 30. One end of the piston boot 23 is fitted in the boot support groove 34. Here, the cylinder hole 30 is not formed with a groove for accommodating the seal member 22 in an intermediate portion in the axial direction thereof.

  An inflow hole 35 penetrating the bottom 31 in the axial direction of the disk rotor 11 is formed in the bottom 31 of the cylinder 26, and the thickness of the bottom 31 from the outer surface opposite to the cylindrical portion 32 of the bottom 31 is formed. The locking hole 36 is formed up to the middle position. The inflow hole 35 is internally threaded, and a unillustrated union bolt provided at an end of an unillustrated brake pipe is screwed together. A locking hook fixed to the tip of the brake pipe is engaged with the locking hole 36, thereby restricting the brake pipe from being rotated when the union bolt is screwed into the inflow hole 35. To do.

  The piston 21 is an integrally molded product formed by forging having a cylindrical tube portion 41 having an inner hole 42 formed therein and a partition wall 43 closing the inner hole 42 of the tube portion 41. The partition wall 43 is formed at an intermediate position in the axial direction of the cylindrical portion 41. The piston 21 may be formed by separating the cylindrical portion 41 and the partition wall 42 and fixing them together by welding or the like.

  The cylindrical portion 41 has a cylindrical shape in which a main outer peripheral surface 45 which is a maximum outer diameter portion has a constant diameter. Further, in the cylindrical portion 41, an end face 46 on one axial side and an end face 47 on the other axial side are arranged in a plane orthogonal to the central axis. The cylindrical portion 41 is formed with a boot groove 51 provided in an annular shape along the circumferential direction on the outer circumference on one end side in the axial direction, and along the circumferential direction on the outer circumference on the other end side in the axial direction. An annular seal groove 52 is formed. The boot groove 51 and the seal groove 52 have an annular shape centering on the central axis of the cylindrical portion 41, and are recessed inwardly in the radial direction of the cylindrical portion 41 from the main outer peripheral surface 45. The outer shape of the main outer peripheral surface 45 is smaller than the inner diameter of the cylinder hole 30. That is, the cylinder part 41 has an outer diameter smaller than that of the cylinder hole 30. The main outer peripheral surface 45 is formed in the outer peripheral range of the cylindrical portion 41 excluding the chamfered portion, the boot groove 51, and the seal groove 52 formed at both axial ends of the cylindrical portion 41.

  Further, the tubular portion 41 has a bulging portion 54 having a shape bulging radially inward from the cylindrical main inner circumferential surface 53 of the tubular portion 41 at the inner circumferential portion on one end side in the axial direction. It is formed so as to form an annular shape along the circumferential direction of the cylindrical portion 41. The bulging portion 54 is provided so as to be aligned with the boot groove 51 in the axial direction of the cylindrical portion 41, and is formed so as to straddle the boot groove 51 in the axial direction. That is, the bulging portion 54 is longer in the axial direction than the boot groove 51, and the axial center position is substantially aligned with the axial position of the boot groove 51.

  In addition, the tubular portion 41 has a bulging portion 55 having a shape bulging radially inward from the main inner peripheral surface 53 of the tubular portion 41 at the inner circumferential portion on the other end side in the axial direction. It is formed so as to form an annular shape along the circumferential direction of 41. The bulging portion 55 is provided in alignment with the seal groove 52 in the axial direction of the cylinder portion 41 and is formed so as to straddle the seal groove 52 in the axial direction. That is, the bulging portion 55 is longer in the axial direction than the seal groove 52, and the axial center position is substantially aligned with the axial center position of the seal groove 52. The main inner peripheral surface 53 is formed in a range of chamfered portions formed at both ends of the cylindrical portion 41 in the axial direction, bulging portions 54 and 55, and the inner hole 42 excluding the partition wall 43.

  The partition wall 43 is formed between the bulging portions 54 and 55 and is spaced apart from the bulging portions 54 and 55 in the axial direction. That is, the partition wall 43 is disposed between both end surfaces 46 and 47 in the axial direction of the cylindrical portion 41, and is spaced apart from the boot groove 51 and the seal groove 52 in the axial direction between the boot groove 51 and the seal groove 52. Is formed. In other words, the boot groove 51 and the seal groove 52 are formed on the outer periphery of the cylindrical portion 41 at a position sandwiching the partition wall 43.

  The boot groove 51 has a cylindrical bottom surface 61 centered on the central axis in the radial direction of the cylindrical portion 41, and a wall surface extending in the radial direction from the edge on the partition wall 43 side of the bottom surface 61 to form an annular shape. 63, and an annular wall surface 62 extending radially outward from the edge of the bottom surface 61 on the end surface 46 side. The wall surfaces 62 and 63 are disposed orthogonal to the central axis in the radial direction of the cylindrical portion 41.

  The seal groove 52 has a cylindrical bottom surface 71 centering on the radial center axis of the cylindrical portion 41, and an annular wall surface extending radially outward from the edge of the bottom surface 71 on the partition wall 43 side. 72 and a wall surface 73 that extends radially outward from the edge of the bottom surface 71 on the end surface 47 side and forms an annular shape. The wall surfaces 72 and 73 are disposed orthogonal to the central axis of the cylindrical portion 41.

  The piston 21 has a mirror-symmetric shape in which a partition wall 43 that is a surface orthogonal to the central axis in the radial direction is provided at the center in the axial direction of the piston 21. That is, the piston 21 has a shape with no distinction between the front and the back with respect to the axial direction. The boot groove 51 and the seal groove 52 have the same shape, and the distance between the boot groove 51 and the end face 46 on the side close to the piston 21 is the end face on the side close to the seal groove 52 and the piston 21. It is formed in the same distance as 47.

  The piston 21 is fitted in the cylinder hole 30 of the caliper body 20. At that time, the end face 46 projects from the cylinder hole 30 toward the disk rotor 11, and the end face 47 is disposed in the cylinder hole 30. The piston 21 accommodates the seal member 22 in a seal groove 52 disposed on the bottom 31 side of the cylinder 26. The seal member 22 is in sliding contact with the radially outer peripheral surface of the piston 21 in close contact with the inner peripheral surface of the cylindrical portion 32 of the caliper body 20, and the radially inner peripheral surface is in close contact with the bottom surface 71 of the seal groove 52. . Accordingly, the seal member 22 seals (seals) the cylinder hole 30 between the outer periphery of the cylinder portion 41 of the piston 21 and the inner periphery of the cylinder hole 30.

  One end of the piston boot 23 is fitted in the boot support groove 34 of the cylinder 26 and connected to the cylinder 26, and the other end is fitted in the boot groove 51 of the piston 21 and connected to the piston 21. The piston boot 23 is disposed so as to cover between the outer periphery of the cylinder portion 41 of the piston 21 and the opening 33 of the cylinder hole 30. The piston boot 23 expands and contracts according to a change in the amount of protrusion of the piston 21 from the cylinder 26.

  In the caliper 15, when brake fluid is introduced into the cylinder hole 30 of the cylinder 26 from the inflow hole 35, brake pressure acts on the partition wall 43 of the piston 21 from the bottom 31 side. Then, the piston 21 advances toward the disk rotor 11 and presses the inner brake pad 13 toward the disk rotor 11. At this time, the end surface 46 of the piston 21 contacts and presses the brake pad 13. As a result, the piston 21 presses the brake pad 13 against the disc rotor 11.

  Further, the caliper body 20 is moved by a reaction force that presses the inner brake pad 13 toward the disk rotor 11, and the outer brake pad 14 is pressed toward the disk rotor 11 by the claw portion 28. As a result, the brake pad 14 is pressed against the disc rotor 11.

  As described above, the caliper 15 sandwiches the pair of brake pads 13 and 14 from both sides by the operation of the piston 21 and presses the both sides of the disc rotor 11. As a result, the caliper 15 gives friction resistance to the disk rotor 11 to generate a braking force of the vehicle.

  The boot groove 51 and the seal groove 52 formed on the outer periphery of the cylinder portion 41 of the piston 21 are formed by spinning so as to sandwich the partition wall 43 in the axial direction of the disk rotor 11. And the bulging parts 54 and 55 are formed with this spinning process. Here, as described above, the piston 21 has a shape that does not distinguish between the front and the back with respect to the axial direction. However, for the sake of clarity of explanation, the end surface 46 and the end surface 47 are distinguished from each other, and the boot groove 51 and The seal groove 52 is distinguished, and the bulging portion 54 and the bulging portion 55 are distinguished and described.

  The piston material 21A shown in FIG. 2 before the boot groove 51 and the seal groove 52 are formed, that is, before the spinning process, is formed with the boot groove 51, the seal groove 52, and the bulging portions 54 and 55 shown in FIG. The cylinder part 41A shown in FIG. 2 before being formed and the partition wall 43 similar to that after the spinning process for closing the inner hole 42A of the cylinder part 41A are provided. The cylindrical portion 41A has a main outer peripheral surface 45A shown in FIG. 2 having a constant diameter that constitutes the main outer peripheral surface 45 shown in FIG. 1 after spinning, and the main outer peripheral surface 45A is formed of the cylindrical portion 41A. It is formed in the whole except the chamfered part of the both ends of the axial direction. The cylindrical portion 41A has a main inner peripheral surface 53A shown in FIG. 2 having a constant diameter, which is part of the main inner peripheral surface 53 shown in FIG. It is formed in the whole except the chamfered part of the axial direction both ends of the cylinder part 41A, and the partition wall 43. The piston material 21A is formed by forging, but may be formed by casting.

  The spinning device 100 shown in FIG. 2 that forms the boot groove 51 and the seal groove 52 shown in FIG. 1 in the cylinder portion 41A of the piston material 21A has one clamp 101 that supports one end portion in the axial direction of the cylinder portion 41A, It has the other clamp 102 which supports the other end part of the axial direction of the part 41A, and the roller 103 which pressurizes the outer periphery of the cylinder part 41A and plastically deforms it.

  The clamp 101 has a base portion 110 and a support portion 111 that protrudes from the base portion 110 and fits to one end portion in the axial direction of the inner hole 42A of the cylindrical portion 41A as shown in FIG. The base portion 110 has a flat contact surface 112 that contacts the end surface 46 of the tubular portion 41A, and the support portion 111 has a cylindrical surface shape facing the main inner peripheral surface 53A on the end surface 46 side of the tubular portion 41A. The outer peripheral surface 113 is provided.

  The clamp 102 includes a base portion 120 and a support portion 121 that protrudes from the base portion 120 and fits to the other end portion in the axial direction of the inner hole 42A of the cylindrical portion 41A. The base portion 120 has a flat contact surface 122 that contacts the end surface 47 of the cylindrical portion 41A, and the support portion 121 has a cylindrical surface shape that faces the main inner peripheral surface 53A on the end surface 47 side of the cylindrical portion 41A. The outer peripheral surface 123 is provided.

  The roller 103 includes a columnar base portion 130, a boot groove forming portion 131 provided on one end side in the axial direction of the base portion 130, and provided annularly along the circumferential direction of the outer periphery of the base portion 130, The seal groove forming portion 132 is provided in an annular shape along the circumferential direction of the outer periphery of the base portion 130 on the other end side in the axial direction of 130. The boot groove forming portion 131 has a cylindrical outer peripheral surface 141 and wall surfaces 142 and 143 on both sides that are arranged perpendicular to the rotational axis of the roller 103 with respect to the outer peripheral surface 141. . The seal groove forming portion 132 also has a cylindrical outer peripheral surface 151 and wall surfaces 152 and 153 on both sides that are arranged perpendicularly to the rotation axis of the roller 103 with respect to the outer peripheral surface 151. . In the embodiment, the molding parts 131 and 132 are formed in the same shape.

  As shown in FIG. 3, the spinning device 100 fits the support portion 111 of one clamp 101 to one end portion in the axial direction of the inner hole 42 </ b> A of the cylinder portion 41 </ b> A. Thereby, the contact surface 112 of the base part 110 contacts the end surface 46 of the cylinder part 41A. Similarly, as shown in FIG. 3, the spinning device 100 fits the support portion 121 of the other clamp 102 to the other end portion in the axial direction of the inner hole 42A of the cylindrical portion 41A. Thereby, the contact surface 122 of the base part 120 contacts the end surface 47 of the cylinder part 41A. And the base parts 110 and 120 pressurize and hold the piston material 21A from both sides in the axial direction with a constant load as long as the piston material 21A does not buckle. In this state, the clamp 101 has the outer peripheral surface 113 of the support portion 111 opposed to the main inner peripheral surface 53A on the end surface 46 side of the cylindrical portion 41A in the radial direction with almost no gap, and the clamp 102 has the outer peripheral surface 123 of the support portion 121. Faces the main inner peripheral surface 53A on the end surface 47 side of the cylindrical portion 41A in the radial direction with almost no gap.

  In this state, while the clamps 101 and 102 and the piston material 21A are integrally rotated at a predetermined rotation speed (for example, 1000 rpm), the roller 103 is brought close to the central axis of the piston material 21A at a predetermined feed speed (for example, 80 mm / min). Then, the molding parts 131 and 132 of the roller 103 are brought into contact with the outer periphery of the cylinder part 41A. The roller 103 rotates in the direction opposite to the rotation direction of the piston material 21A by contacting the piston material 21A.

  Then, the boot groove forming part 131 pressurizes the outer peripheral surface of the cylinder part 41A shown in FIG. 3 toward the central axis side to cause plastic deformation, thereby forming the boot groove 51 as shown in FIG. At that time, the outer peripheral surface 141 of the boot groove forming portion 131 forms the bottom surface 61 of the boot groove 51, the wall surface 142 of the forming portion 131 forms the wall surface 62 of the boot groove 51, and the wall surface 143 of the forming portion 131 is the boot groove. 51 wall surfaces 63 are formed. By forming the boot groove 51 in this manner, the bulging portion 54 is formed by the movement of the meat mainly inward in the radial direction of the tubular portion 41A. At this time, the support portion 111 and the partition wall 43 of the clamp 101 are cylinders on both sides in the axial direction of the boot groove forming portion 131 against the radially inward pressing of the cylindrical portion 41A shown in FIG. 3 by the boot groove forming portion 131. The part 41A is supported. Thereby, it is possible to secure a pressing force necessary for forming the boot groove 51 while suppressing the deformation of the end face 46.

  Further, in parallel with the formation of the boot groove 51 by the boot groove forming part 131, the seal groove forming part 132 pressurizes the outer peripheral surface of the cylinder part 41A toward the central axis side to cause plastic deformation, As shown in FIG. 4, a seal groove 52 is formed. At that time, the outer peripheral surface 151 of the seal groove forming portion 132 forms the bottom surface 71 of the seal groove 52, the wall surface 152 of the seal groove forming portion 132 forms the wall surface 72 of the seal groove 52, and the wall surface of the seal groove forming portion 132. 153 forms the wall surface 73 of the seal groove 52. By forming the seal groove 52 as described above, the bulging portion 55 is formed by moving the corresponding meat mainly inward in the radial direction of the cylindrical portion 41. At this time, the support portion 121 and the partition wall 43 of the clamp 102 are axially moved in the axial direction of the seal groove forming portion 132 against the radially inward pressing of the cylindrical portion 41A shown in FIGS. 3 and 4 by the seal groove forming portion 132. The cylinder portion 41A is supported on both sides. Thereby, it is possible to secure a pressing force necessary to form the seal groove 52 while suppressing the deformation of the end face 47.

  As described above, by forming the two grooves, that is, the boot groove 51 and the seal groove 52, by one spinning process, as shown in FIG. 4, the boot groove 51, the seal groove 52 and the bulge are formed in a short time. The piston 21 having the parts 54 and 55 is obtained. Thereafter, as shown in FIG. 5, the roller 103 and the clamps 101 and 102 are separated from the piston 21, and the spinning process is finished. The piston 21 after the spinning process is assembled to the caliper body 20 after the plating process is performed, and constitutes the disc brake 10.

  The disc brake described in Patent Document 1 is provided with a seal groove on the cylinder bottom side of the piston. However, Patent Document 1 does not describe a method for forming a seal groove, and is presumed to be formed by cutting as in the conventional case. Therefore, it cannot be said that the manufacturing efficiency of the piston is high. Furthermore, the disk brake described in Patent Document 1 is not provided with the boot groove 51 of the embodiment in the piston.

  On the other hand, according to the disc brake 10 according to the embodiment, the cylindrical portion 41 of the piston 21 is spun so that the boot groove 51 and the seal groove 52 sandwich the partition wall 43 in the axial direction of the disc rotor 11. Is formed by. That is, in the manufacturing method of the piston 21 according to the embodiment, the annular boot groove 51 and the seal groove 52 are formed at positions sandwiching the partition wall 43 by pressurizing and plastically deforming the outer periphery of the cylinder portion 41A. Therefore, compared with the case where the boot groove 51 and the seal groove 52 are formed by cutting, the manufacturing efficiency of the piston 21 can be improved, and as a result, the manufacturing efficiency of the disc brake 10 can be improved.

  In addition, the boot groove 51 and the seal groove 52 are formed by spinning, that is, the inner periphery of the cylinder part 41 is formed by forming the boot groove 51 and the seal groove 52 by plastically deforming the outer periphery side of the cylinder part 41A. The bulging portions 54 and 55 are formed on the side. For this reason, by forming the boot groove 51 and the seal groove 52, the portion whose strength is weakened can be reinforced by the bulging portions 54 and 55. Therefore, compared with the case where the boot groove 51 and the seal groove 52 are formed by cutting, the overall thickness of the cylindrical portion 41 of the piston 21 necessary for obtaining the same strength can be reduced. Therefore, the weight of the piston 21 can be reduced, and consequently the disc brake 10 can be reduced in weight.

  Further, the boot groove 51 and the seal groove 52 are subjected to spinning processing so as to sandwich the partition wall 43 in the axial direction of the disk rotor 11, that is, by plastically deforming the outer peripheral side of the cylindrical portion 41 </ b> A so as to sandwich the partition wall 43. Since it is formed, the partition wall 43 can suppress deformation of the cylinder portion 41A. Therefore, the accuracy of the boot groove 51 and the seal groove 52 can be improved.

  Further, since the boot groove 51 and the seal groove 52 are formed simultaneously by spinning, the lead time of the manufacturing process can be shortened as compared with the case where they are formed separately, and the manufacturing efficiency of the piston 21 is further increased. Can be improved. In addition, since the spinning process load is symmetrical on both sides of the piston 21 in the axial direction, the machining load is balanced and the workability is stabilized.

  In addition, the piston 21 has a mirror-symmetric shape with respect to the central surface in the axial direction orthogonal to the central axis, and has a shape that does not distinguish between the front and the back with respect to the axial direction. This eliminates the need for confirmation and improves the workability of the assembly work. Here, the partition wall 43 may be shifted from the center in the axial direction as long as the partition wall 43 is formed to be spaced apart from the bulging portions 54 and 55 in the axial direction. By changing the position of the partition wall 43, the center of gravity of the piston 21 can be changed. Therefore, the partition wall 43 can be disposed at a position where brake noise can be effectively suppressed. The boot groove 51 and the seal groove 52 may be formed in different sizes, and the distance between the boot groove 51 and the end face 46 may be different from the distance between the seal groove 52 and the end face 47.

  In the above description, the case where the two grooves of the boot groove 51 and the seal groove 52 are formed at the position sandwiching the partition wall 43 of the piston 21 has been described as an example. However, it is formed by pressurizing the outer periphery of the cylindrical portion 41A and plastically deforming it. It is also possible to form three or more annular grooves along the circumferential direction of the cylinder portion 41A at positions where the partition wall 43 is sandwiched. That is, at least two annular grooves along the outer peripheral direction of the cylinder portion 41 </ b> A may be formed at positions where the partition wall 43 is sandwiched.

  The disc brake according to the embodiment described above is provided across the outer periphery of the disc rotor, and is movable in the cylinder hole, and a caliper body having a cylinder hole opening toward the disc rotor in the axial direction of the disc rotor. The cylinder hole is disposed between the outer periphery of the cylinder portion of the piston and the inner periphery of the cylinder hole. A disc brake comprising: a seal member that seals between the outer periphery of the cylinder portion of the piston and an opening of the cylinder hole. A boot groove that is annularly provided along the circumferential direction of the cylindrical portion on one end side of the outer periphery and in which the end portion of the piston boot is fitted, and the circumferential direction of the cylindrical portion on the other end side of the outer periphery of the cylindrical portion Provided annularly along the seal groove said seal member is accommodated, but is formed by spinning so as to sandwich the partition wall in the axial direction of the disc rotor.

  Thus, the boot groove and the seal groove are formed in the cylindrical portion of the piston by spinning so as to sandwich the partition wall in the axial direction of the disk rotor. Therefore, compared with the case where the boot groove and the seal groove are formed by cutting, the manufacturing efficiency of the piston can be improved, and as a result, the manufacturing efficiency of the disc brake in which it is incorporated can be improved.

  In addition, since the bulging portion is formed on the inner peripheral side of the cylindrical portion when the boot groove and the seal groove are formed by spinning, the strength is weakened by forming the boot groove and the seal groove. The part which becomes can be reinforced with the bulging part. Therefore, compared with the case where the boot groove and the seal groove are formed by cutting, the overall thickness of the cylindrical portion necessary for obtaining the same strength can be reduced. Therefore, the weight of the piston can be reduced, and consequently the disc brake in which the piston is incorporated can be reduced in weight.

  In addition, since the boot groove and the seal groove are formed by spinning so as to sandwich the partition in the axial direction of the disk rotor, the partition can be prevented from being deformed by the partition. Therefore, the accuracy of the boot groove and the seal groove can be improved.

  A piston manufacturing method according to an embodiment includes a caliper body having a cylinder hole that opens toward the disk rotor in the axial direction of the disk rotor, a piston that is movably disposed in the cylinder hole, and a disk brake that includes In the manufacturing method of the piston used, the piston is formed by including a cylindrical portion having an outer diameter smaller than the cylinder hole and a partition wall closing the inner hole of the cylindrical portion, At least two annular grooves are formed on the outer periphery along the circumferential direction of the cylindrical portion at a position sandwiching the partition wall by pressurizing the outer periphery of the cylindrical portion to cause plastic deformation.

  In this manner, at least two annular grooves are formed at positions sandwiching the partition wall by pressurizing the outer periphery of the tube portion and plastically deforming the outer periphery of the tube portion. Therefore, compared with the case where at least two annular grooves are formed by cutting, the manufacturing efficiency of the piston can be improved, and as a result, the manufacturing efficiency of the disc brake incorporating the piston can be improved.

  Further, as the at least two annular grooves are formed by plastically deforming the outer peripheral side of the cylindrical portion, a bulging portion is formed on the inner peripheral side of the cylindrical portion. For this reason, the part by which an intensity | strength becomes weak by forming at least 2 cyclic | annular groove | channel can be reinforced with a bulging part. Therefore, compared with the case where at least two annular grooves are formed by cutting, the overall thickness of the cylinder portion of the piston necessary for obtaining the same strength can be reduced. Therefore, the weight of the piston can be reduced, and consequently the disc brake in which the piston is incorporated can be reduced in weight.

  In addition, since at least two annular grooves are formed by pressurizing and plastically deforming the outer periphery of the cylinder so as to sandwich the partition in the axial direction of the disc rotor, the deformation of the cylinder is suppressed by the partition. Can do. Therefore, the accuracy of at least two annular grooves can be improved.

DESCRIPTION OF SYMBOLS 10 Disc brake 11 Disc rotor 20 Caliper main body 22 Seal member 23 Piston boot 30 Cylinder hole 33 Opening 41 Cylindrical part 42 Inner hole 43 Partition 51 Boot groove 52 Seal groove

Claims (2)

A caliper body provided across the outer periphery of the disk rotor and having a cylinder hole that opens toward the disk rotor in the axial direction of the disk rotor;
A piston that is movably disposed in the cylinder hole and has a cylindrical portion and a partition wall that closes the inner hole of the cylindrical portion;
A seal member that seals the cylinder hole between an outer periphery of the cylindrical portion of the piston and an inner periphery of the cylinder hole;
A piston boot disposed between the outer periphery of the cylindrical portion of the piston and the opening of the cylinder hole;
In a disc brake comprising
In the cylinder part,
A boot groove provided annularly along the circumferential direction of the cylindrical portion on one end of the outer periphery of the cylindrical portion, and into which an end of the piston boot is fitted;
A seal groove that is annularly provided along the circumferential direction of the cylinder part on the other end side of the outer periphery of the cylinder part, and that accommodates the seal member;
However, the disc brake is formed by spinning so as to sandwich the partition in the axial direction of the disc rotor. In the manufacturing method of the piston used for a disc brake comprising: a caliper body having a cylinder hole opening toward the disc rotor in the axial direction of the disc rotor; and a piston arranged to be movable in the cylinder hole.
The piston,
A cylindrical portion having an outer diameter smaller than the cylinder hole;
A partition wall for closing the inner hole of the cylindrical portion;
Forming a piston material having
A method for manufacturing a piston, wherein at least two annular grooves along the circumferential direction of the cylindrical portion are formed at a position sandwiching the partition wall on the outer periphery of the cylindrical portion by pressurizing the outer periphery of the cylindrical portion to cause plastic deformation.

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