JPH06254645A - Production of internal gear - Google Patents

Abstract

PURPOSE:To improve a yield of material, to increase a strength of an internal gear and to improve the workability. CONSTITUTION:A metal plate 24 as a blank of a frame is punched and a waste hole 26 is formed. On a circumferential part of the waste hole 26, the metal plate 24 is pressed and a 1st order cylindrical part with a bottom whose bottom wall has the waste hole 26 is formed. A R-corner part of the bottom side of the 1st order cylindrical part is reduced, the circumferential wall is formed so as to be made straight and a 2nd cylindrical part is obtained. Ant internal gear is preliminarily formed on an internal surface of the circumferential wall of the 2nd order cylindrical part and a 3rd cylindrical part is obtained, further, the internal gear 20 is really formed and a 4th order cylindrical part 56 is obtained. The cylindrical part is formed with drawing (including bulging) due to mainly the material flow from the internal side of the metal plate 24, that is, from the circumferential periphery of the waste hole 26 outward the radiant direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an internal gear used in a lock mechanism of a webbing retractor for a vehicle.

[0002]

2. Description of the Related Art In a webbing take-up device for a vehicle, a take-up shaft for taking up the webbing is hung between the leg plates of a U-shaped frame having a pair of opposing leg plates, and the webbing is normally wound. Although the webbing can be pulled out from the winding shaft, the webbing cannot be pulled out when the vehicle is rapidly decelerated because the winding shaft is locked.

In order to lock the take-up shaft, the internal gear is arranged coaxially with the take-up shaft on one of the leg plates of the frame, and one end of the take-up shaft extends so that the take-up shaft is locked inside the internal gear. The lock claw that penetrates through the shaft and is provided at the extended end of the winding shaft and rotates with the winding shaft protrudes radially outward when the vehicle suddenly decelerates and meshes with the internal gear to rotate the winding shaft. Prevent.

Here, it is conceivable to form the internal gear integrally with the frame of the winding device.

The applicant of the present invention has previously described a method for manufacturing an internal gear in which the internal teeth are integrally formed with the frame as described in Japanese Patent Application No.
Proposed in No. 291570.

According to this method, first, a metal plate which is a material of the frame is subjected to press working including a reverse drawing at a portion which becomes one of the leg plates to obtain a tubular portion.

After that, internal teeth are formed on the inner circumference of the tubular portion.
Next, a hole through which the extended end of the winding shaft can penetrate is formed in the bottom of the tubular portion.

[0008]

By the way, according to the above-described method for manufacturing the internal gear, as shown in FIG. 11, the cylindrical portion 102 is formed by drawing by the material flow from the outside of the metal plate 104. Therefore, on the outer periphery of the tubular portion 102, the outer dimension of the metal plate 104 after forming (width dimension W2 of the metal sheet) is smaller than the outer dimension before forming (width dimension W1 of the metal sheet).

Therefore, it is necessary to prepare a metal plate having a large width in advance in anticipation of a reduction in the outer size of the metal plate, and the material yield is poor.

[0010] In particular, when the metal plate for obtaining the tubular portion is formed with the tubular portion and other shaped portions such as smaller shapes, the yield is further deteriorated.

Further, since the press working includes reverse drawing,
There is a possibility that the strength of the peripheral wall of the tubular portion may be reduced, and thus the strength of the internal teeth formed there may be reduced.

Further, the operability is not good, for example, the drawing direction is reversed and a reversing work is required. In consideration of the above facts, the present invention improves the yield of materials, improves the strength of internal teeth,
An object of the present invention is to provide a method for manufacturing an internal gear having good workability.

[0013]

In order to solve the above-mentioned problems, the present invention provides a step of forming a hole in a plate material, and a bottom wall having the hole formed by pressing the plate material at the peripheral portion of the hole. The present invention proposes a method for manufacturing an internal gear having a step of forming an attached tubular portion and a step of forming internal teeth on an inner surface of a peripheral wall of the tubular portion.

[0014]

According to the method of manufacturing an internal gear according to the present invention, the holes formed in the plate material in advance become waste holes, and the cylindrical portion mainly flows from the inside of the plate material, that is, from the periphery of the hole. It is molded by squeezing (including overhang).

Therefore, the material flow from the outside of the plate material is suppressed, the outer dimension of the plate material at the outer periphery of the tubular portion is prevented from becoming smaller after the upper part of the tube is molded, and a good material yield is obtained.

Further, since the tubular portion is formed by drawing by the material flow from the inside of the plate material, the moldability is improved and the tubular portion can be easily formed without including the reverse drawing in the press working.

As a result, the peripheral wall of the tubular portion has sufficient strength,
Therefore, the internal teeth formed there have sufficient strength, and it is not necessary to reverse the drawing direction, and workability is improved.

Further, since the holes are provided, the mold contact with the bottom wall during molding of the tubular portion is reduced, and the load exerted by the mold on the bottom wall is reduced.

When the internal teeth formed on the inner surface of the peripheral wall of the tubular portion are formed by press working using an inner die and an outer die, the material is removed from the peripheral edge of the hole between the inner die and the outer die. , The filling of the material for forming the internal teeth is improved, and the internal teeth have a proper shape.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing an internal gear according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 7 shows a frame 10 of a vehicle webbing retractor. The frame 10 has a U-shape, and a take-up shaft (not shown) for taking up the webbing is stretched between a pair of facing leg plates 12 and 14. An internal gear 16 integrated with the frame 10 is formed on one leg plate 12.

That is, on one of the leg plates 12, a bottomed cylindrical portion 18 coaxial with the winding shaft is recessed inward of the frame 10, and the cylindrical portion 18 has internal teeth 20 on the inner surface of the peripheral wall thereof. At the same time, a through hole 22 is formed in the bottom wall. One end of the winding shaft extends from the through hole 22 into the tubular portion 18 and penetrates the tubular portion 18. Normally, the webbing can be pulled out from the take-up shaft, but when the vehicle suddenly decelerates, a lock claw (not shown) that rotates with the take-up shaft is provided at the extended end of the take-up shaft. Internal teeth 20 protruding outward in the direction
And the rotation of the winding shaft is blocked, and the webbing cannot be pulled out.

The internal gear 16 is manufactured by the method described below. First, as shown in FIG.
The metal plate 24, which is the 0 material, is punched to form the discard hole 26. The discard hole 26 is a circular hole having the axis of the winding shaft as a center line, and the hole diameter D1 of the discard hole 26 is smaller than the hole diameter D2 of the through hole 22. Also, the metal plate 2
The width of 4 is W3, and the plate thickness is t1.

Next, as shown in FIG. 2, the metal plate 24 is pressed around the periphery of the discard hole 26 to obtain the bottomed primary cylindrical portion 30 having the discard hole 26 in the bottom wall 28. In the primary tubular portion 30, the R corner portion on the bottom side is large, the side wall 32 is inclined, and the depth is D1. Primary tubular part 30
At the time of molding, the annular convex portion 34 having a step of height H is simultaneously formed on the outer peripheral portion of the opening.

Next, the R corner portion on the bottom side of the primary molding portion 30 is reduced, and molding is performed with the peripheral wall 32 being straight. Thereby, as shown in FIG. 3, the secondary cylindrical portion 36 is obtained.

Next, internal teeth are preformed on the inner surface of the peripheral wall 38 of the secondary tubular portion 36. As shown in FIG. 8, both the inner peripheral surface of the outer mold 40 and the outer peripheral surface of the inner mold 42 are formed in a tooth shape (wavy shape) having the same number of concavities and convexities. (Corresponding to P1) is larger than the pitch circle of the concavities and convexities of the inner mold 42 (corresponding to P2 shown in FIG. 4). Further, the unevenness of the inner mold 42 has an obtuse and rounded shape than the tooth shape of the inner teeth 20. The concave portion 46A of the inner mold 42 and the convex portion 44B of the outer mold 40 are located at corresponding positions, and the convex portion 46 of the inner mold 42 is located.
The inner mold 42 and the outer mold 40 are arranged so that B and the recess 44A of the outer mold 40 are located at the corresponding positions, and the inner mold 42 and the outer mold 40 are relatively moved in the axial direction.

As a result, as shown in FIGS. 4 and 9,
The tertiary cylindrical portion 5 in which the peripheral wall 48 has the same wall thickness and is corrugated in the circumferential direction.
0 is obtained.

Next, the inner teeth are main-molded. As shown in FIG. 9, the outer mold 40 is the same as the preform, and the inner mold 52
Has concaves and convexes (concave portion 70A, convex portion 70B) having an acute angle so as to obtain the tooth shape of the inner teeth 20. Outer mold 40 and inner mold 52
5, the relationship between the number of concavities and convexities (the pitch circle of the outer die 40 corresponds to P1 shown in FIG. 5 and the pitch circle of the inner die 52 corresponds to P3 shown in FIG. 5), and Molding is performed in the same manner as in the case of preforming the internal teeth with respect to the arrangement relationship of the concavities and convexities.

As a result, as shown in FIG. 5, the peripheral wall 54
A quaternary tubular portion 56 having internal teeth 20 (see FIG. 10) on its inner surface is obtained.

In this main forming, the quaternary tubular portion 56
Of the annular convex portion 34 on the outer peripheral portion of the opening of the above, and the V-shaped groove 58 formed by being pressed by the annular jig remains,
The R corner of the opening peripheral edge of the quaternary tubular portion 56 is made smaller.

As a result, the depth D2 of the quaternary tubular portion 56
Is a step H (see FIG. 1) from D1 (see FIG. 1).
By making the depth shallower, a straight tooth tip can be obtained over substantially the entire length of the depth D2. Compared to the case where the tubular portion is formed without forming the step H, the internal teeth 20 with respect to the depth of the tubular portion are
A wide effective tooth width can be obtained.

Further, since the entire thickness of the peripheral wall of the tubular portion is formed in a wavy shape in the circumferential direction (the outer peripheral surface of the tubular portion has an uneven shape correspondingly to the inner peripheral surface). , Internal teeth 20
The bottom has a sufficiently thick wall and sufficient strength can be obtained.

The inner teeth 20 have ratchet tooth shapes in FIGS. 5 and 10, but the shape of the teeth does not matter.

Next, as shown in FIGS. 6 and 10, the periphery of the discard hole 26 is adjusted, and punching is performed so that the discard hole is slightly enlarged to obtain the through hole 22. Note that the waste hole 26 gradually increases as the material flows from the inner side, which will be described later, at the time of each molding described above.
The hole diameter of the discard hole 26 is predetermined.

The outer edge of the metal plate 24 is cut and trimmed to obtain a predetermined width. Since the material flow from the inner side is the main, the material flow from the outer side is small, and therefore, the cutting and trimming portion is extremely small.

Next, the metal plate 24 is subjected to processing such as bending in a U-shape to obtain the frame 10 having a predetermined shape.

In this way, the internal gear 16 is manufactured. The tubular portion is mainly formed by drawing (including overhanging) by the material flow from the inside of the metal plate 24, that is, from the peripheral edge of the discard hole 26 to the outside in the radial direction.

Therefore, the material flow from the outside of the metal plate 24 is suppressed, the outer dimension of the metal plate 24 on the outer periphery of the tubular portion is prevented from becoming smaller after the tubular portion is molded, and a good material yield is obtained. can get. Since the abandonment hole 26 will be used later as the through hole 22, it is not inconvenient to form the abandonment hole 26 in advance, and it is particularly suitable when the peripheral edge of the abandonment hole 26 need not be arranged.

Further, since the tubular portion is formed by drawing by the material flow from the inside of the metal plate 24, the moldability is improved and the press working does not include the reverse drawing (in one direction drawing). The tubular portion can be easily molded. Particularly, it is effective when the annular convex portion 34 is formed.

As a result, the peripheral wall of the tubular portion has sufficient strength,
Therefore, the internal teeth 20 formed there have sufficient strength, and it is not necessary to reverse the drawing direction, which improves workability.

Furthermore, the presence of the waste hole 26 reduces the contact of the die with the bottom wall of the tubular portion during the molding of the tubular portion, and the load exerted by the die on the bottom wall is reduced.

The internal teeth 2 formed on the inner surface of the peripheral wall of the tubular portion
When 0 is formed by pressing using the inner molds 42 and 52 and the outer mold 40, the material flows between the inner mold and the outer mold radially outward from the peripheral edge of the discard hole 26. Therefore, the filling property of the material for forming the internal teeth is improved, and the internal teeth 20 have an appropriate shape.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, in the above embodiment, the method for manufacturing the internal gear used for the lock mechanism of the webbing retractor for a vehicle has been described, but the internal gear is not limited to such use.

In the above embodiment, the inner teeth are formed by pressing on the inner circumference of the cylindrical portion. However, even if the inner teeth are formed by another method such as cutting, the function and effect of the present invention will not be obtained. I can't reduce it.

[0045]

According to the method for manufacturing an internal gear according to the present invention, the material yield is improved, the strength of the internal teeth is improved,
Good workability can be obtained.

[Brief description of drawings]

FIG. 1 shows a first step of a method for manufacturing an internal gear according to an embodiment of the present invention, (A) is a plan view of a metal plate,
FIG. 1B is a sectional view taken along line 1 (B) -1 (B) of FIG.

FIG. 2 shows a second step, (A) is a plan view of the metal plate seen from the opening side of the tubular portion, and (B) is 2 (B) -2 (of FIG. 2 (A). B) is a sectional view taken along the line.

FIG. 3 shows a third step, (A) is a plan view of the metal plate seen from the opening side of the tubular portion, and (B) is 3 (B) -3 (of FIG. 3 (A). B) is a sectional view taken along the line.

FIG. 4 shows a fourth step, (A) is a partially cutaway plan view of the metal plate seen from the opening side of the tubular portion, and (B) is
4 (B) -4 (B) line sectional view of FIG. 4 (A).

FIG. 5 shows a fifth step, (A) is a partially cutaway plan view of the metal plate seen from the opening side of the tubular portion, and (B) is
5 (B) -5 (B) line sectional view of FIG. 5 (A).

FIG. 6 shows a sixth step, (A) is a partially cutaway plan view of the metal plate seen from the opening side of the tubular portion, and (B) is
6 (B) -6 (B) line sectional view of FIG. 6 (A).

FIG. 7 is a perspective view showing a frame of a seat belt retractor to which an internal gear obtained by the manufacturing method of this embodiment is applied.

FIG. 8 is a perspective view showing a state immediately before a fourth step.

FIG. 9 is a perspective view showing a state immediately before a fifth step.

FIG. 10 is a perspective view showing an internal gear obtained in a sixth step.

FIG. 11 is a plan view of a tubular portion of an internal gear, which is obtained by a conventional manufacturing method, as viewed from the opening side.

[Explanation of symbols]

 18 Cylindrical part 20 Internal teeth 24 Metal plate (plate material) 26 Discard hole (hole)

Claims (1)

[Claims] 1. A step of forming a hole in a plate member, a step of pressing the plate member at a peripheral portion of the hole to form a bottomed tubular portion having the hole, and a peripheral wall of the tubular portion. A method of manufacturing an internal gear, comprising the step of forming internal teeth on the inner surface.