WO2000016930A1 - Method of manufacturing latch plate - Google Patents

Abstract

A method of manufacturing a ring-shaped metallic latch plate (11) having internal ratchet teeth (20) on the inner peripheral surface thereof using a punch (30) having a forging tooth-shaped edge (31) for forming the internal ratchet teeth and a pilot (32) provided at the axially forward side of the edge, comprising the steps of first forming a prepared hole (12) in the metallic latch plate (11), disposing the punch (30) so that the pilot (32) is aligned with the prepared hole (12) so as to engage the forging tooth-shaped edge (31) with the peripheral edge part (13) of the prepared hole (12), and then driving the forging tooth-shaped edge (31) so that the peripheral edge part (13) is extruded by cold forging so as to form the internal ratchet teeth (20) around the periphery of the prepared hole.

Description

 Specification

Manufacturing method of latch plate

Technical field

 The present invention relates to a method for manufacturing a latch plate having internal ratchet teeth.

Background art

 As shown in Fig. 1, the latch plate 10 used for the retractable seatbelt mechanism of the automobile has inner ratchet teeth 20, but the inner ratchet teeth 20 receive an impact load. In this case, the inner ratchet teeth 20 are required to have high precision in shape and phase because they are engaged with the corresponding claws to be used for locking the seat belt. In the conventional latch plate 10, the inner ratchet teeth 20 are formed by shaping with a press.

 However, a metal plate formed by shaving a metal plate such as carbon steel has a problem that the surface finish and strength are inevitably insufficient. Things are sought. The present invention has been made in view of such a point, and an object of the present invention is to provide a method of manufacturing a latch plate which can easily manufacture a high-quality latch plate.

Disclosure of the invention

In the manufacturing method according to the present invention, the ring-shaped metal latch plate 10 having the inner ratchet teeth 20 on the inner periphery is provided on the forging toothed edge 31 for forming the inner ratchet teeth and at the axial end thereof. It is manufactured by using a punch 30 provided with a pilot 32. First, a pilot hole 12 is formed in a metal plate 11 and then the punch 30 is arranged to form the pilot 32. Matches above prepared holes 1 and 2 Then, the forged toothed edge 31 is engaged with the peripheral edge 13 of the prepared hole 12, and then the forged toothed edge 31 is driven into the peripheral edge 13 by cold forging. Extrude to form the inner ratchet teeth 20 around the pilot hole 12. As described above, in the present invention, the pilot 32 is provided at the tip through the pilot hole 12, and is extruded by cold forging using the punch 30 having the forging toothed edge 31 on the outer peripheral surface. Since the inner ratchet teeth 20 are formed, a high-precision one can be obtained at a lower cost than in the case where the inner ratchet teeth are formed by cutting or the like, and the inner ratchet is formed by cold forging extrusion. In order to form the teeth, the inner ratchet teeth can be given a thickness greater than the thickness of the metal plate, so that the strength of the inner ratchet gear can be increased. In addition, by adjusting the amount of cold extrusion, it is possible to obtain inner ratchet teeth of any thickness within the range of the amount of extrusion.

 In addition, the forging toothed edge 31 is driven in, and the peripheral portion 13 is extruded by cold forging to form the inner ratchet teeth 20 around the pilot hole 12 and at the same time, along the inner ratchet teeth. If the thin fins 15 extending from one side of the metal plate are left so as to connect between the teeth 21 of the ratchet teeth 20 and the thin fins 15 are subsequently removed, the punch A part of the metal plate can escape to the thin fins 15 during the cold forging extrusion, and the inner ratchet teeth with higher precision can be reliably formed, and the life of the mold can be extended. .

A mold 40 is provided on the upper surface for receiving the peripheral edge 13 of the pilot hole 12 in the metal plate 11. The mold 40 is provided with the above-mentioned inner ratchet teeth 20 for forming the inner ratchet teeth 20. A mold hole 41 is provided for receiving the pilot 32 when the punch 30 is driven. The inner diameter of the mold hole 41 is slightly larger than the diameter of the pipe mouth, and a minute clearance C is formed therebetween, so that the peripheral portion 13 Can be extruded into the minute clearance C to form a thin burr 16 extending from the thin fin 15 in the thickness direction of the metal plate. If 16 is subsequently removed together with the thin fins 15, a more accurate inner ratchet tooth can be obtained by allowing a part of the metal plate to escape to the small clearance C during cold forging extrusion by punching. You can really get it.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plan view of a latch plate obtained by the manufacturing method of the present invention. 2A to 2D are cross-sectional views showing the steps of the manufacturing method of the present invention.

FIG. 3 is a schematic cross-sectional view showing a punch and a die used in the method for manufacturing a latch plate of the present invention.

FIG. 4 is a perspective view showing the latch plate during the same manufacturing process. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, the present invention will be described in detail based on an example of an embodiment. A latch plate 10 to be obtained by a manufacturing method according to the present invention has inner ratchet teeth 20 on an inner peripheral surface as shown in FIG. A plurality of mounting holes 22 are formed in an outer peripheral portion of the ring-shaped member, and a plurality of positioning pins 23 are fixed to the ring. The thickness T2 of the inner peripheral portion is larger than the thickness T1 of the outer peripheral portion.

The latch plate 10 is formed by, for example, providing a prepared hole 12 in a metal plate 11 made of JIS standard S45C carbon steel and forging and pressing it. As shown in FIG. 3, this forging press is composed of a punch 30 and a lower die 42 having an insert die 40 for receiving a peripheral portion 13 of a prepared hole 12 of a metal plate 11. . The outer periphery of the tip of the punch 30 is provided with a toothed edge 31 for cold forging extrusion. The pilot 32 protrudes into the body from the tip. In addition, the insert mold 40 in the lower mold 42 has a mold hole 41 into which the pie mouth 31 of the punch 30 is fitted during forging press.

 2A to 2D and FIG. 3 show steps of a method for manufacturing the latch plate 20. After the pilot hole 12 is formed in the flat metal plate 11 as shown in Fig. 2A, the peripheral part 13 of the pilot hole 12 is protruded to one side as shown in Fig. 2B to form a ring. Form ribs 14. Thereafter, as shown in FIG. 3, the metal plate 11 is placed on the lower mold 42 and the annular rib 14 is made to correspond to the upper surface of the insert mold 40. In this state, the pilot 32 of the punch 30 is made to protrude through the pilot hole 12 into the mold hole 41 of the insert mold 40, and the punch 30 is driven into the toothed edge 31 so that the peripheral edge 13 is formed. By plastic deformation, as shown in FIG. 2C, the inner ratchet teeth 20 are extruded on the peripheral part 13 by cold forging. At this time, the peripheral portion 13 where the inner ratchet teeth 20 are formed is mainly plastically deformed in the thickness direction of the metal plate 11 so that the thickness T2 of the inner ratchet teeth 20 before the forging is obtained. The thickness is larger than the thickness T 1 of the annular rib and the outer peripheral portion of the metal plate 11.

 The driving amount of the punch 30 is set before the axial end of the toothed edge 31 reaches the upper surface of the insert mold 40. That is, the position where the punch 30 is lowered most is set such that a minute clearance is generated between the upper surface of the insert mold 40 and the axial end of the toothed edge 31 of the punch 30. As a result, when the inner ratchet teeth 20 are formed by performing cold forging of the peripheral portion 13 by the punch 30, as shown in FIGS. 2C and 4, a part of the peripheral portion 13 has a minute clearance. The thin fins 15 over the entire circumference of the cutting edge of the inner ratchet teeth 20 are left on one side of the metal plate 11 so as to connect between the teeth 21 of the inner ratchet teeth 20. .

The inner diameter of the mold hole 41 of the insert mold 40 is While making it slightly smaller than the inner diameter of the tangent circle and making the outer diameter of the pilot 32 slightly smaller than the inner diameter of the mold hole 41, a small clearance C is created between the outer surface of the pilot 32 and the inner surface of the mold hole 41. I have to. For this reason, when the inner ratchet teeth 20 are formed by performing cold forging of the peripheral portion 13 with the punch 30, a part of the peripheral portion also escapes to this minute clearance, and as shown in FIG. As shown in FIG. 4, the thin fins 16 that hang down continuously from the inner peripheral edge of the thin fins 15 are formed. By actively forming such thin fins 15 and thin burrs 16, the formation of the inner ratchet teeth 20 in the cold forging extrusion by the teeth 31 of the punch 30 can be performed precisely without dripping. Can be obtained as The thin fins 15 and the thin burrs 16 are formed over the entire circumference of the prepared hole. After the inner ratchet teeth 20 have been formed by cold forging as described above, the insert mold 40 is pushed up by the knockout pins 43, and the metal plate 11 attached to the punch 30 is placed around the punch 30. It is removed from the punch by the stripper plate 35 arranged.

 After the inner ratchet teeth 20 are formed as described above, the peripheral portion 13 including the thin fins 15 and the thin burrs 16 below the broken line shown in Fig. 2C is punched by cutting or pressing. By removing by processing, the inner ratchet teeth 20 are finished to the final shape as shown in FIG. 2D. In this case, at the same time, the latch plate 10 shown in FIG. 1 is obtained by adjusting the outer shape of the metal plate 11 or performing press forming for forming the mounting hole 22. In addition, the tooth surface of the inner ratchet tooth 20 may be basically the same as that at the time of performing the cold forging extrusion described above, and it is not necessary to correct the tooth surface by grinding. In order to keep the relative accuracy between the mounting holes 22 and the positioning pins 23 and the inner ratchet teeth 20 high, the outer shape, the mounting holes 22 and the positioning pins 23 with respect to the inner ratchet teeth 20 are used as a reference. It is preferable to form them simultaneously.

Claims

The scope of the claims 1. A ring-shaped metal latch plate having inner ratchet teeth along the circumference is manufactured using a forging toothed edge for forming the inner ratchet teeth and a punch provided with a pilot at the tip end in the axial direction from the forged toothed edge. A method for manufacturing a latch plate comprising the following steps:  Forming a pilot hole in the metal plate;  Disposing the punch to align the pilot with the pilot hole to engage the forging toothed edge with the periphery of the pilot hole;  The forged toothed edge is driven in the direction of the pressure of the metal plate, and the peripheral portion is extruded by cold forging to form the inner ratchet teeth around the pilot hole. 2. Driving the forged toothed edge and extruding the peripheral portion by cold forging to form the inner ratchet teeth around the pilot hole, and each of the inner ratchet teeth along the cutting edge of the inner ratchet teeth. 2. The method according to claim 1, wherein a thin fin extending on one surface of the metal plate is left so as to connect between teeth, and the thin fin is subsequently removed. 3. A mold is provided on the upper surface to receive the periphery of the pilot hole in the metal plate, and the mold receives the pipe when the punch is driven to form the inner ratchet teeth. A mold hole is provided, and the inside diameter of the mold hole is slightly larger than the diameter of the pier mouth to form a minute clearance therebetween, and a part of the peripheral portion is extruded into the minute clearance. It is possible to form a thin burr extending from the thin fin in the thickness direction of the metal plate, and the thin burr is removed together with the thin fin. 3. The production method according to claim 2, wherein: 4. The production method according to claim 2, wherein the thin fin extends over the entire circumference of the pilot hole. 5. The method according to claim 3, wherein the thin burr extends over the entire circumference of the pilot hole.