JP2011190853A - Method of manufacturing backing plate for drum brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a backing plate for a drum brake which has a cable guide part higher than the limit height of a conventional cable guide part while reducing the number of parts of the drum brake and securing the strength thereof. <P>SOLUTION: A part 64b of a disk member 64 is raised to the brake cable 58 side by a drawing in a drawing step P2 by which a local reduction in plate thickness does not tend to more occur than by a cutting and bending, and a part 64e of the raised disk member 64 is cut and bent by the cutting and bending step P3. Therefore, a height H2 through which the longitudinal center part of the part 64e of the disk member 64 is cut and bent to the brake cable 58 side by the cutting and bending step P3 is lower than the height H of the cable guide part 18f through which the longitudinal center part of a part of a conventional disk member is cut and bent. Consequently, a reduction in the plate thickness occurring locally when the cable guide part 18f is formed is smaller than in the case of the conventional cable guide part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a drum brake backing plate, and more particularly to a technique for improving the function of the drum brake backing plate.

  For example, a drum brake backing plate 100 as shown in FIGS. 13 and 14 is known. The drum brake backing plate 100 shown in FIGS. 13 and 14 includes a brake cable 110 having one end connected to a tip of a brake lever rotatably provided on one of a pair of brake shoes. 100 is supported and guided by a longitudinal cable guide portion 100c bent between the parallel cut surfaces 100b from a part 100a to the brake cable 110 side, and the cable guide is integrated with the backing plate 100. Since the portion 100c is provided, there is an advantage of reducing the number of parts of the drum brake. As shown in FIG. 15, the cable guide portion 100 c includes a punch 120 whose front end portion 120 a protrudes toward the part 100 a of the backing plate 100, and a die 130 having a concave surface 130 a for pressing between the punch 120. Is used to cut and bend the central portion in the longitudinal direction of the portion 100a of the backing plate 100 so that the central portion in the longitudinal direction of the portion 100a of the backing plate 100 protrudes toward the bottom side of the concave surface 130a. It is to be molded.

JP 2005-133911 A

  However, in the method of manufacturing the drum brake backing plate 100 as described above, if the cable guide portion 100c is formed by press working using the punch 120 and the die 130 as described above, the tip of the punch 120 during press working is formed. Since the load concentrates from the portion 120a to the central portion in the longitudinal direction of the portion 100a of the backing plate 100, the punch 120 and the concave surface 130a of the die 130 do not contact at the central portion in the longitudinal direction of the portion 100a of the backing plate 100. The plate thickness of the portion becomes intensively thinner as the tip 120a of the punch 120 approaches the bottom of the concave surface 130a of the die 130. Therefore, when the height H of the cable guide portion 100c is increased as shown in FIG. 13, the partial width dimension D of the cable guide portion 100c is locally small and the plate thickness is locally as shown in FIG. There is a problem that it becomes difficult to secure the strength required to support and guide the brake cable 110 when the drum brake is braked. Therefore, when the cable guide portion 100c is formed by pressing in the drum brake backing plate 100, the height H has a design limit.

  In Patent Document 1, a cable guide having the same function as that of the cable guide portion 100c is attached to the backing plate as a separate component in order to ensure a sufficient strength higher than the limit height of the conventional cable guide portion 100c. In this case, there is a problem that the number of parts of the drum brake increases and the manufacturing cost of the drum brake increases.

  The present invention has been made against the background of the above circumstances. The purpose of the present invention is to reduce the number of parts of the drum brake and maintain the strength from the limit height of the conventional cable guide portion. An object of the present invention is to provide a method for manufacturing a drum brake backing plate having a high cable guide.

  To achieve this object, the gist of the invention according to claim 1 is that: (a) a brake having one end connected to a tip of a brake lever rotatably provided on one of a pair of brake shoes; A method of manufacturing a drum brake backing plate for supporting and guiding a cable from a part of the backing plate to a side of the brake cable by a longitudinal cable guide portion formed between cut surfaces parallel to each other. (B) a first punch having a tip side flat surface projecting toward the backing plate side in parallel with the flat plate portion of the backing plate, and a first die having a drawing surface for drawing between the first punch. A part of the backing plate is parallel to the flat plate portion of the backing plate by the front end side plane of the first punch. (C) having a concave surface for pressing between the second punch having a tip-side convex surface protruding to a part of the backing plate and the tip-side convex surface of the second punch. Using a second die, a cutting step of further bending a portion of the backing plate protruding in parallel to the flat plate portion of the backing plate to the brake cable side by the drawing step to the brake cable side, There is to include.

  According to the manufacturing method of the drum brake backing plate of the invention according to claim 1, a part of the backing plate is parallel to the flat plate portion of the backing plate by the tip side plane of the first punch by the drawing step. A part of the backing plate that protrudes to the cable side and then protrudes to the brake cable side by the drawing process by the cutting process is further cut and bent to the brake cable side. Therefore, a part of the backing plate is raised to the brake cable side by the drawing process of the drawing process, which is less likely to cause a local decrease in the plate thickness compared to the cutting process of the cutting and bending process, and the bottom is raised. Since a part of the backing plate is cut and bent by the cutting and bending process, the height at which the central part of the longitudinal direction of the part of the backing plate is cut and bent to the brake cable side by the cutting and bending process is the conventional cable guide part. Compared to lower. As a result, a reduction in the plate thickness that occurs locally when the cable guide portion is formed by the cutting and bending step is smaller than that of the conventional cable guide portion, and the plate thickness of the cable guide portion is reduced to the conventional cable guide portion. Therefore, it is possible to increase the limit height of the cable guide portion of the present invention as compared with the limit height of the conventional cable guide portion while ensuring the strength.

It is a front view showing a duo servo type drum brake to which the present invention is applied. It is the II-II sectional view taken on the line of FIG. FIG. 3 is a III-III view of FIG. 2. It is process drawing for demonstrating the manufacturing method of the backing plate for drum brakes. It is a perspective view which shows the disc member shape | molded by the preliminary press process. It is a perspective view explaining the drawing press processing machine used at a drawing process. It is sectional drawing explaining the state by which a part of disk member is drawn by the drawing process. It is a perspective view which shows the disk member shape | molded by the drawing process. It is a perspective view explaining the cutting and bending press processing machine used at a cutting and bending process. It is sectional drawing explaining the state by which the 1st shape part of a disc member is cut and bent by a cutting and bending process. It is a perspective view which shows the disc member shape | molded by the cutting and bending process. It is the figure seen from the arrow B direction of FIG. It is a figure which shows the cable guide part of the conventional backing plate. It is a XIV-XIV view of FIG. It is a figure explaining the manufacturing method of the cable guide part of the conventional backing plate.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a front view of a duo-servo type drum-in disc brake 12 with a drum brake 10 according to an embodiment of the present invention provided at the center thereof with a hat-type disc and calipers removed. The hat-type disc is composed of a disc-shaped outer peripheral portion and a bottomed cylindrical central portion not shown in the drawing, and the disc-shaped outer peripheral portion functions as a friction plate for the disc brake, and has a bottomed cylindrical central portion. The part functions as a brake drum 14. The brake drum 14 is represented by two concentric circles indicated by a one-dot chain line in FIG. 1, and the circle on the center side of the drum brake 10 of the two circles indicates the inner peripheral surface 16 of the brake drum 14. ing.

  The drum brake 10 has a substantially disc shape and is, for example, a backing plate (drum brake backing plate) integrally fixed to a vehicle body side member, that is, a non-rotating member such as an axle tube, an axle housing, and a suspension device (not shown). ) 18 is provided. A disc cover 20 is secured to the outer periphery of the backing plate 18 to protect the disc-like outer periphery of the hat type disc.

  Also, the drum brake 10 includes a pair of arc-shaped brake shoes 22 and 24 disposed substantially symmetrically so as to be close to and away from each other in a posture in which the convex side is outward on the left and right outer peripheral portions of the backing plate 18, An anchor 26 provided in a fixed position between one end of the pair of brake shoes 22 and 24, that is, the upper end of FIG. 1, and a pair of brakes stretched between the anchor 26 and the pair of brake shoes 22 and 24 A pair of return springs 28, 30 that always urge one end of the shoes 22, 24 toward each other, and a longitudinal plate-like strut 32 spanned between the upper ends of the pair of brake shoes 22, 24; 1 is interposed between the other end portions of the pair of brake shoes 22 and 24, that is, the lower end portion of FIG. 1, and the total length changes as the adjustment wheel 34a rotates. The gap adjusting device 34 that adjusts the shoe clearance by being applied, and the gap adjusting device 34 that is stretched between the lower ends of the pair of brake shoes 22 and 24 and constantly urges the lower ends to approach each other. An intermediate portion for pinching in the longitudinal direction is provided with a coiled spring 36.

  Each of the pair of brake shoes 22, 24 is formed into a flat plate shape substantially parallel to the flat plate portion 18 a of the backing plate 18, and the shoe webs 38, 40 are curved in an arc shape in the front view shown in FIG. Adhered to the belt-like shoe rims 42 and 44, which are integrally fixed so that the cross-section is substantially T-shaped along the outer peripheral edge of the arc shape, and the outer peripheral surfaces of the shoe rims 42 and 44 And linings 46 and 48 made of a friction material fixed integrally with an agent or the like.

  The pair of brake shoes 22, 24 are pressed against the backing plate 18 by being pressed toward the backing plate 18 by shoe hold-down devices 50, 52 disposed on the shoe web 38 and the shoe web 40, respectively. It is held so as to be able to move in the direction of expansion.

  As shown in FIG. 1, the brake shoe 22 is provided with a flat brake lever 56 having a substantially cylindrical mounting shaft 54, and one end portion of the brake shoe 22 and a base end portion of the brake lever 56. 56a is connected by the attachment shaft 54 so that relative rotation is possible around the attachment shaft 54. The base end portion 56a of the brake lever 56 that is close to the mounting shaft 54 is engaged with the notch surface 32a cut out at the end portion of the strut 32 on the brake shoe 22 side together with the shoe web 38. . In addition, an operating force generated by operating a brake operating device (not shown) such as a parking brake pedal or a parking brake lever is transmitted to the tip 56b of the brake lever 56 to the tip 56b of the brake lever 56. A brake cable 58 is connected.

  As shown in FIGS. 2 and 3, the backing plate 18 is fitted with a mounting hole 18 b formed on the outer peripheral side of the backing plate 18, and a cable attaching member 60 for attaching the brake cable 58 to the backing plate 18. A portion of the flat plate portion 18a of the backing plate 18 is drawn so as to protrude from the portion adjacent to the mounting hole 18b of the backing plate 18 to the brake cable 58 side, and cut from the tip portion of the drawn portion 18c. A cable guide integrally formed with a longitudinally cut and bent portion 18e that is cut by bending and is convexly bent so as to protrude further toward the brake cable 58 between the cut parallel cut surfaces 18d. 18f.

  The cable attachment member 60 is made of an elastically deformable material such as plastic or synthetic rubber, and the fitting projection 60a fitted into the attachment hole 18b from a part of the cable attachment member 60 and the brake cable 58 can be inserted. A through hole 60b that is penetrated by the cable attachment member 60 in size is provided. A coil spring 62 compressed in the longitudinal direction is disposed around the brake cable 58 between the cable mounting member 60 and the tip end portion 56 b of the brake lever 56, and is urged by the biasing force of the coil spring 62. The tip 56b of the brake lever 56 is always biased in the direction opposite to the pulling direction in which the brake cable 58 is pulled, that is, in the direction opposite to the rotation direction F.

  The cable guide portion 18 f supports the brake cable 58 via the coil spring 62, and one end portion of the brake cable 58 is substantially the same as the flat plate portion 18 a of the backing plate 18 in the rotation direction F of the distal end portion 56 b of the brake lever 56. The height H of the cable guide portion 18f is set so as to guide in a parallel state.

  Here, the backing plate 18 for the drum brake 10 having the cable guide portion 18f is manufactured, for example, as follows. Hereinafter, the manufacturing method will be described with reference to FIGS. FIG. 4 is a process diagram for explaining a method of manufacturing the backing plate 18 for the drum brake 10.

  First, in the pre-pressing step P1 shown in FIG. 4, a disc-shaped steel plate having a uniform thickness (not shown) is punched into a predetermined shape and subjected to a predetermined bending, so that the disk member (backing) shown in FIG. Plate 18) 64 is formed. By this preliminary pressing step P1, the disk member 64 is formed in almost any shape other than the cable guide portion 18f formed by the backing plate 18.

  FIG. 6 is a perspective view for explaining the drawing press machine 66 used in the drawing process P2 shown in FIG. As shown in FIGS. 6 and 7, the drawing press machine 66 includes a flat plate portion of the disc member 64 toward a part 64 b of the flat plate portion 64 a of the disc member 64 attached to the draw press machine 66. A first punch 68 having a tip side flat surface 68a protruding substantially parallel to 64a, and the first punch 68 is recessed at a depth distance H1 shallower than the height H of the cable guide portion 18f for drawing. A first die 70 having a diaphragm surface 70a is provided. Further, the part 64b of the flat plate portion 64a of the disk member 64 indicates a longitudinal region surrounded by a one-dot chain line shown in FIG.

  In the drawing process P2, the disk member 64 is placed on the first die 70 as shown in FIG. 7A on the left side of FIG. 7 so that the surface of the disk member 64 is not wrinkled during drawing. A wrinkle pressing plate 72 that presses the surface portion of the disk member 64 is disposed on the surface of the disk member 64. Thereafter, the first punch 68 is moved in the direction of the arrow G by a driving device (not shown) provided in the drawing press machine 66 and comes into contact with a part 64b of the disk member 64, and the right side (b of FIG. As shown in the drawing, a part 64 b of the disk member 64 is drawn by the first punch 68 and the drawing surface 70 a of the first die 70. Through the drawing process P2, the height 641 of the disk member 64 is set to a height H1 lower than the height H of the cable guide portion 18f as shown in FIG. As shown in FIG. 8, the first shape portion 64c and the flat portion of the first shape portion 64c that is substantially parallel to the front end side plane 68a of the first punch 68, that is, substantially parallel to the flat plate portion 64a of the disc member 64. A first flat plate portion 64d whose height from 64a is raised by H1 is formed.

  In the drawing process P2, a part 64b of the flat plate portion 64a of the disc member 64 is formed into the first shape portion 64c by drawing, so that the average plate thickness of the first shape portion 64c is the disc member 64. It is thinner than the flat plate portion 64a. However, the first shape portion 64c formed by the drawing step P2 has an experiment such that the thickness thereof is sufficient to support and guide the brake cable 58 when the drum brake 10 is braked. It is a shape designed by the above and has a sufficient strength. Further, the plate thickness of the first shape portion 64c formed by the drawing step P2 is not necessarily uniform, and there is a portion where the plate thickness decreases locally, but the cable guide portion is formed by cutting and bending. In comparison, the local reduction amount of the plate thickness is very small, and the plate thickness of the first shape portion 64c is substantially uniform.

  FIG. 9 is a perspective view illustrating the cutting and bending press machine 74 used in the cutting and bending step P3 shown in FIG. As shown in FIGS. 9 and 10, the cutting and bending press machine 74 has a front-end-side convex surface 76 a that protrudes toward the first flat plate portion 64 d of the first shape portion 64 c attached to the cutting and bending press processing machine 74. In order to cut and bend between the second punch 76 and the front-side convex surface 76a of the second punch 76, a first surface having a concave surface 78a recessed at a depth distance H similar to the height H of the cable guide portion 18f. 2 dice 78 are provided.

  In the cutting and bending process P3, as shown in FIG. 10A on the left side, the first shape portion 64c of the disk member 64 is placed on the second die 78 and is the wrinkle presser plate 72 in the same manner as in the drawing process P2. Is disposed on the surface of the disk member 64. Thereafter, the second punch 76 is moved in the direction of arrow I by a driving device (not shown) provided in the cutting and bending press machine 74, and comes into contact with the first flat plate portion 64d of the first shape portion 64c, as shown in FIG. A part 64e of the first flat plate portion 64d is cut and bent by the second punch 76 and the second die 78, as shown in the right (b) diagram. By the cutting and bending process P3, the first shape portion 64c of the disk member 64 is set to a height H equivalent to the height H of the cable guide portion 18d as shown in FIG. 10B on the right side of FIG. It is formed into a two-shaped portion 64f. Further, the part 64e of the first flat plate part 64d of the first shape part 64c indicates a longitudinal region surrounded by a one-dot chain line shown in FIG.

  In the cutting and bending step P3, the load concentrates from the tip of the tip side convex surface 76a of the second punch 76 to the central portion in the longitudinal direction of the part 64e of the first flat plate portion 64d of the first shape portion 64c. Sometimes, the plate thickness of the non-contact portion between the second punch 76 and the concave surface 78a of the second die 78 at the central portion in the longitudinal direction of the portion 64e of the first shape portion 64c, that is, the local portion 64g is locally reduced.

  However, when the first shape portion 64c is formed into the second shape portion 64f by the cutting and bending step P3, the longitudinal center portion of the part 64e of the first shape portion 64c is on the bottom side of the concave surface 78a of the second die 78. Since the second shape portion 64f is formed by being cut and bent by a distance H2 shorter than the height H of the cable guide portion 18f, the longitudinally central portion of a part of the disk member 64 is cabled by conventional cutting and bending. The height of cutting and bending by the cutting and bending step P3 is lower than that of cutting and bending to the height H of the guide portion 18f. That is, the part 64b of the disk member 64 is lowered by the height H1 raised by the drawing process P2. Therefore, the thickness reduction of the local portion 64g of the second shape portion 64f due to the cutting and bending process P3 is made smaller than the thickness reduction of the conventional cable guide portion, and the thickness of the local portion 64g of the second shape portion 64f is conventionally increased. It becomes thicker than the plate thickness of the cable guide.

  Further, the height H2 of cutting and bending from the part 64e of the first shape portion 64c by the cutting and bending step P3 is such that the plate thickness of the local portion 64g of the second shape portion 64f is braked when the drum brake 10 is braked by the cutting and bending step P3. The second shape portion 64f supports and guides the brake cable 58 when the drum brake 10 is braked. The thickness of the second shape portion 64f is set so as to be thick enough to support and guide the 58. It has sufficient strength. As shown in FIG. 10, the height distance H1 of the first shape portion 64c formed by the drawing step P2 and the longitudinal center portion of the part 64e of the first shape portion 64c are cut and bent by the cutting step P3. The total of the height distance H2 to be obtained corresponds to the height H of the cable guide portion 18f.

  As shown in FIG. 9, the thickness dimension A of the second punch 76 is slightly shorter than the width dimension of the hole 78b recessed by the concave surface 78a of the second die 78, and the second punch 76 has the first shape portion. When abutting against the first flat plate portion 64d of 64c and being fitted into the recessed hole 78b of the second die 78, a part 64e of the first flat plate portion 64d of the first shape portion 64c is second as shown in FIG. The punch 76 is cut by the outer peripheral edge in the thickness direction of the punch 76 and the opening edge of the hole 78b of the second die 78, and at the same time is bent between the parallel cutting surfaces 64h to be formed into the second shape portion 64f. The The cutting and bending process of the cutting and bending press machine 74 in the cutting and bending process P3 performed in the present embodiment is a process of bending a part 64e of the flat plate part 64d of the first shape part 64c at the same time as cutting.

  FIG. 11 is a perspective view showing the disk member 64 formed by the cutting and bending process P3. Finally, the disk member 64 is pressed by the finishing process P4 shown in FIG. Is manufactured. Further, the second shape portion 64f formed by the cutting and bending step P3 is the same as the cable guide portion 18f of the backing plate 18.

  In the drum brake 10 having the backing plate 18 manufactured as described above, when an operating force is generated in the brake cable 58 by operating the brake operating device, the cable guide portion 18f supports the brake cable 58. The tip 56b of the brake lever 56 is guided in the rotation direction F. As a result, the brake lever 56 rotates in the rotation direction F, the brake shoe 24 is pushed by the strut 32, and the brake shoe 22 is pushed by the mounting shaft 54, so that the linings 46, 48 of the pair of brake shoes 22, 24 are moved. It contacts the inner peripheral surface 16 of the brake drum 14.

  According to the manufacturing method of the backing plate 18 for the drum brake 10 of the present embodiment, a part 64b of the flat plate portion 64a of the disk member (backing plate 18) 64 is caused by the tip side flat surface 68a of the first punch 68 by the drawing step P2. A part 64e of the disk member 64 protruding to the brake cable 58 side substantially parallel to the flat plate portion 64a of the disk member 64 and then protruding to the brake cable 58 side by the drawing process P2 by the cutting and bending process P3 is further braked. The cable 58 is cut and bent. Therefore, a part 64b of the flat plate portion 64a of the disk member 64 is raised to the brake cable 58 side by the drawing process of the drawing process P2, which is unlikely to cause a local decrease in the plate thickness compared to the cutting and bending process of the cutting and bending process P3. Since the part 64e of the disk member 64 whose bottom is raised is cut and bent by the cutting and bending process P3, the longitudinal center part of the part 64e of the disk member 64 is cut to the brake cable 58 side by the cutting and bending process P3. The bending height H2 is lower than that obtained by cutting and bending the longitudinal central portion of a part of the conventional disk member to the height H of the cable guide portion 18f. As a result, the reduction of the plate thickness locally generated when the cable guide portion 18f is formed by the cutting and bending process P3 is smaller than that of the conventional cable guide portion, and the plate thickness of the cable guide portion 18f is reduced to the conventional cable guide portion. Therefore, the maximum height of the cable guide portion 18f can be made higher than that of the conventional cable guide portion while ensuring the strength. Further, as shown in FIGS. 3, 12, and 14, in the conventional cable guide portion 100c and the cable guide portion 18f of this embodiment, the width dimension D of the cable guide portion is also reduced as the thickness of the cable guide portion decreases. Therefore, when the thickness of the tip of the cable guide portion 18f that contacts the brake cable 58 becomes thicker than that of the conventional cable guide portion 100c, the width dimension of the cable guide portion 18f also becomes larger than that of the conventional cable guide portion 100c. Therefore, it becomes difficult for the brake cable 58 to fall off from the cable guide portion 18f.

  As mentioned above, although the Example of this invention was described based on drawing, this invention is applied also in another aspect.

  For example, in the manufacturing method of the backing plate 18 for the drum brake 10 of this embodiment, in the drawing process of the drawing process P2, a part 64b of the flat plate portion 64a of the disk member 64 is formed into a shape as shown in FIG. However, it is not always necessary to make the shape as described above, and it may be formed into any shape as long as it has a flat surface cut and bent by the cutting and bending step P3.

  Although not illustrated one by one, the present invention can be implemented in variously modified and improved modes based on the knowledge of those skilled in the art.

10: Drum brake 18 (64): Backing plate (disc member)
18a (64a): Flat plate portion 18d (64h): Cut surface 18f (64f): Cable guide portion (second shape portion)
22, 24: a pair of brake shoes 56: brake lever 56b: tip 58: brake cable 68: first punch 68a: tip side plane 70: first die 70a: throttle surface 76: second punch 76a: tip side convex surface 78 : Second die 78a: concave surface P2: drawing process P3: cutting and bending process

Claims (1)

A brake cable having one end connected to a tip of a brake lever rotatably provided on one of a pair of brake shoes is connected between a part of the backing plate and a side parallel to the brake cable. A method of manufacturing a drum brake backing plate that is supported and guided by a bent longitudinal cable guide,
Using a first punch having a tip side flat surface protruding parallel to the flat plate portion of the backing plate to the backing plate side, and a first die having a drawing surface for drawing between the first punch, A throttling step of projecting a part of the backing plate to the brake cable side in parallel with the flat plate portion of the backing plate by a front end side plane of the first punch;
The squeezing step using a second punch having a front-side convex surface protruding to a part of the backing plate and a second die having a concave surface for pressing between the front-side convex surface of the second punch. And a bending step of further bending the portion of the backing plate protruding toward the brake cable side in parallel with the flat plate portion of the backing plate toward the brake cable side. Manufacturing method.

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