JPS59193726A - Punch for engraving groove - Google Patents

Abstract

PURPOSE:To provide a titled punch which prevents the shear droop at the shoulder of a groove, decreases a finishing allowance by machining and improves yield in grooving on a sliding contact surface of a brake disc by forming the tip of a punch into a crest shape having a ridgeline and expanding the width of the groove by both edges of the slope next to the ridgeline. CONSTITUTION:While a brake disc (a) is kept pressed by a blank holder, a longitudinal groove (b) is punched thereon by means of a punch 1. A crest shape 2 of the punch 1 having a ridgeline is penetrated into the disc and in succession, the groove is expanded by the side faces 3 at the sloped tip. The retracting shear droop of the disc (a) surface is minimized by such expansion by which the later finishing allowance by machining is decreased and the yield of the material is improved. If the part near the center of a groove (b) is made shallow and wide, the residual stress of the disc (a) is lessened and generating of a strain is obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a punch for carving grooves on a grooved brake disc, mainly used in disc brakes for motorcycles.

Conventionally, this type of brake disc is known, for example, as shown in Fig. 1, a brake disc a has a groove in which longitudinal grooves are carved in the radial direction on the groove sliding surface of the brake disc a to improve water drainage. However, the groove engraving process is generally performed using a punch C having a tip with a rectangular cross section as shown in Fig. However, in order to take out the edge of the shoulder, it became necessary to grind the butt sliding surface to the position of the dotted water in Figure 2, which increased the grinding allowance, which made processing time-consuming and resulted in poor material yield. It comes with some inconvenience.

SUMMARY OF THE INVENTION In order to eliminate such inconveniences, it is an object of the present invention to provide a punch that can suppress the occurrence of sagging at the groove shoulder as much as possible. In a punch that carves a longitudinal groove in the radial direction on a surface, the tip surface of the punch body is formed in a chevron shape with a ridge line at the center in the groove width direction, and the punch body has grooves extending from both sides of the tip surface. A feature in that both side surfaces of the tip are inclined in a direction to widen the groove width, and one longitudinal end of the tip surface located on the radially inner end side of the groove is inclined in a direction to reduce the groove depth. The present invention will be specifically explained with reference to the embodiments shown in FIG. 3 and below.

In the drawing, (1) indicates the punch body, and the punch body (1)
As shown in Figure 4, the blank holder (6) has a substantially convex cross section that is slidably inserted into the guide hole (6a) of the blank holder (6) which is elastically supported on the press die (5), and the workpiece of the holder (6) Upon contact with the barrel brake disc a, the tip of the punch body (1) protrudes to the outer surface of the holder (6) and forms a diameter corresponding to the shape of the tip on the nogut sliding surface of the disc a. A longitudinal groove is carved in the direction.

The cross-sectional shape of the tip of the punch body (1) 9 is a hole as shown in FIG. Both sides of the tip part f3) (3) connected to both side edges of 2) shall be inclined in the direction of widening the groove width, and furthermore, as shown in Figs. 3 and 6, the inner end side in the radial direction of the groove One longitudinal end (4) of the distal end surface (2) located at is inclined in the direction of decreasing the groove depth.

Next, to explain its operation, the tip of the punch body (1) is press-fitted into the notched sliding surface of the brake disc a, which is the workpiece, while pushing apart the meat with the chevron-shaped tip surface (2). , press-fit load movement can be reduced, and at this time both sides of the tip (
3) (3) effectively functions to prevent the meat pushed apart by the edge surface (2) from being caught in the press-fitting direction and to bring the meat closer to the shoulder of the groove. The occurrence of shaking in the shoulder area is suppressed as much as possible.

In addition, if the tip surface (2) is formed in a chevron shape having the same height over the one longitudinal end (4) described above, the engraved part of the groove and the non-engraved part are separated from each other by the radial inner edge of the groove. A large internal stress difference may occur between the engraved portion and the end portion (4), which may cause distortion due to residual stress after heat treatment, and may cause damage to the end portion (4) due to uneven load during press-fitting. According to the present invention, the end portion (4
) is tilted in the direction of decreasing the groove depth, this problem will not occur.

As described above, according to the present invention, the tip surface of the punch body is formed into a chevron shape, and both sides of the tip are inclined in the direction of widening the groove width, so that the meat is not gathered to the shoulder of the groove. The occurrence of wobbling is suppressed, the grinding process after grooving becomes easy, and the material shape becomes good. This reduces the internal stress difference that occurs between the inner circumference of the brake disc and the non-engraved part of the groove, effectively preventing distortion of the brake disc and breakage of the punch, increasing productivity. This has the effect of improving performance and reducing costs.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a brake disc, FIG. 2 is a cross-sectional view of a conventional punch, FIG. 3 is a plan view of an example of the punch of the present invention, and FIG. 5 is an enlarged cross-sectional view of the main part thereof, and FIG. 6 is a cross-sectional view taken along the line VI-Vll of FIG. 3.

Claims (1)

[Claims] In a punch that carves a longitudinal groove in the radial direction on the butt sliding surface of a brake disc, the tip surface of the punch body is formed in a chevron shape with a ridge line at the center in the groove width direction, and grooves are formed on both sides of the tip surface. Both side surfaces of the leading end of the punch body are inclined in a direction that widens the groove width, and one longitudinal end of the leading end located on the radially inner end side of the groove is tilted in a direction that reduces the groove depth. A groove installation punch characterized by being inclined.