KR20180081189A - Non-working safety belt pretensioners development of high-precision cold forging process technology and key component parts - Google Patents

Abstract

The present invention relates to a method of manufacturing a seat belt pretensioner wheel gear, comprising the steps of: preparing a cylindrical blank (B) by cutting a round steel bar; A first heat treatment step (S20) of annealing and softening the blank (B); A first coating step (S30) of coating the softened heat-treated blank (B) with a coating agent; The formed cylindrical blank B is forged to form the first formed body S1 having the gear tooth 1 at the outer peripheral portion of the first cylindrical body 5 and the intermediate concave circular bottom face portion 3 Forming a preliminary forging step (S40); After the first formed body S1 is positioned in the piercing mold, the circular bottom face portion 3 is pierced to form a through groove 13 at the center and gear teeth 11 are formed on the outer peripheral portion of the second circumferential body 15 A piercing step S50 for molding the second formed body S2; A third heat treatment step (S60) of annealing and softening the second formed body (S2); A third coating step (S70) of coating the softened heat-treated second formed body (S2) with a coating agent; The second formed body S2 is cold-forged to form a through groove 23 formed at the center of the third circumferential body 25 and a gear tooth 21 formed at the outer circumferential portion and a groove width 21 along the inner circumferential portion The ball grooves 27 and the ball supporting grooves 27 corresponding to the ball grooves 27 are formed so that the shape of the ball grooves 27 becomes larger and the groove width becomes larger and smaller, And a final forging step (S80) of forming a third formed body (S3) provided with the first and second formed bodies (27a, 27a).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for manufacturing a safety belt pretensioner wheel gear using a high-precision cold forging,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a factory safety belt pretensioner wheel gear (one-way clutch) using a high-precision cold forging.

 The role of the seatbelt is very simple. It is designed to prevent my body from falling out of the seat regardless of the type of impact, so that it can prevent contact with elements arranged in front of the steering wheel, instrument panel, windshield etc. . The current seatbelt is called a three-point seat. This is because there are three fixed parts. Hold it from left to right and hold it from one shoulder. It is to give the impact evenly to the most durable body and pelvis in the body. The rear seat middle belt is usually a 2-point type with only the waistline, which is also replaced with a 3-point type of car these days.

The safety belt pretensioner is a safety system that operates when the built-in sensor detects sudden deceleration due to an accident. The seatbelt pretensioner is a device that instantaneously rewinds the seatbelt when a collision from the front of the vehicle is detected, thereby improving the effectiveness of the seatbelt by reducing the amount of forward movement of the passenger. The seatbelt pretensioner mechanically senses the deceleration of the vehicle separately from the airbag system and mechanically operates to rewind the seatbelt by actuation of the gas generator. The seat belt pretensioner is mounted on the driver's seat and the front passenger's seat and operates separately. Seat belt wheel gears operate both inside and outside the ball, and the seat belt is pulled when the outer ball passes. At this time, the inner ball acts as a one-way clutch and returns to one direction, causing a high-load stress.

Registration No. 10-0422658 as prior art of automobile component forging is provided with a punch provided on the upper side of the product when the clutch gear is forged, a punch provided on the lower side of the punch with the product therebetween, Wherein the die is formed on the opposite side of the punch with a dentition formed by a tooth extrusion and a tooth outer diameter, and the dentition from a tooth outer diameter to a tooth outer diameter is formed by pressing the punch And is formed so as to be inclined with respect to a horizontal plane perpendicular to the direction of rotation of the clutch gear.

The prior art seems to have been manufactured in such a way that the shape of the safety belt pretensioner one-way clutch is complicated and the cutting process is mainly performed by hot forging. There is a problem that the material loss and machining cost are high in the cutting process, the strength is lowered by the method of hot forging, and the compactness is weak.

The present invention has the strength and durability to withstand the high load due to the safety belt operation by producing the wheel gear for the safety belt pretensioner by the high precision cold forging and can ensure the dimensional accuracy by the precision machining by the cold forging, Despite the complicated inner and outer shapes, no additional cutting process is required (no cutting), smooth operation is facilitated by the smooth operation of the forging die when using the forging lubricant, ensuring excellent surface roughness of the wheel gear, To provide a manufacturing method and apparatus for a manufacturing process of a safety belt pretensioner wheel gear using high-precision cold forging.

In addition, the present invention can solve problems in high-load operation due to durability and strength improvement because there is no internal defect due to compression due to cold forging and there is no disconnection of mearal flow due to plastic deformation, (1-way clutch) can be formed, and it is possible to manufacture without additional major cutting. The surface of the product after cold forging is very smooth due to mold surface roughness and forging lubricant. And to provide a manufacturing method and a manufacturing apparatus for a manufacturing process of a safety belt pretensioner wheel gear using a high-precision cold forging capable of securing excellent surface roughness.

A method for manufacturing a safety belt pretensioner wheel gear using a high-precision cold forging according to the present invention is a method for manufacturing a safety belt pretensioner wheel gear, comprising the steps of: preparing a cylindrical blank (B) by cutting a round steel bar material; A first heat treatment step (S20) of annealing and softening the blank (B); A first coating step (S30) of coating the softened heat-treated blank (B) with a coating agent;

The formed cylindrical blank B is forged to form the first formed body S1 having the gear tooth 1 at the outer peripheral portion of the first cylindrical body 5 and the intermediate concave circular bottom face portion 3 Forming a preliminary forging step (S40);

After the first formed body S1 is positioned in the piercing mold, the circular bottom face portion 3 is pierced to form a through groove 13 at the center and gear teeth 11 are formed on the outer peripheral portion of the second circumferential body 15 A piercing step S50 for molding the second formed body S2;

A third heat treatment step (S60) of annealing and softening the second formed body (S2); A third coating step (S70) of coating the softened heat-treated second formed body (S2) with a coating agent;

The second formed body S2 is cold-forged to form a through groove 23 formed at the center of the third circumferential body 25 and a gear tooth 21 formed at the outer circumferential portion and a groove width 21 along the inner circumferential portion The ball grooves 27 and the ball supporting grooves 27 corresponding to the ball grooves 27 are formed so that the shape of the ball grooves 27 becomes larger and the groove width becomes larger and smaller, And a final forging step S80 for molding the third formed body S3 provided with the first molded body 27a.

According to the present invention, since the wheel gear for the seatbelt pretensioner is produced by high-precision cold forging, it has strength and durability to endure a sudden high load due to the operation of the seatbelt and ensures dimensional accuracy by precision machining by cold forging (No cutting process) even in the case of complicated inner and outer shapes, it is possible to smoothly operate smoothly by smooth operation of the forging die when using forging lubricant, thereby ensuring excellent surface roughness of the wheel gear, There is provided a method and an apparatus for manufacturing a factory safety belt pretensioner wheel gear using high-precision cold forging.

In addition, according to the present invention, since internal defects are eliminated by compression due to cold forging, plastic deformation does not cause breakage of the mearal flow, so that durability and strength can be improved and problems can be solved at high load operation. It is possible to form outer side gears and it is possible to form inner side complicated shape (one way clutch), so that it is possible to manufacture without additional important part cutting. The surface of product after cold forging by mold surface roughness and forging lubricant There is provided a process for manufacturing a safety belt pretensioner wheel gear using a high-precision cold forging capable of ensuring excellent surface roughness because it is very smooth.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual view of a method of manufacturing a seat belt pretensioner wheel gear according to the present invention;
Fig. 2 is a third assembled forging mold assembly of the present invention. Fig.
Fig. 3 is an upper punch constructional view of Fig. 2; Fig.
Figure 4 is a central counter punch (lower) configuration diagram of Figure 2;
Fig. 5 is an external counter punch (lower) configuration diagram of Fig. 2; Fig.
Fig. 6 is a bottom die configuration diagram of Fig. 2; Fig.
Fig. 7 is a second molded product manufacturing forged mold assembly view of the present invention. Fig.
8 is a second upper punch construction view of Fig.
9 is a second counter punch configuration diagram of Fig.
Fig. 10 is a second lower die configuration diagram of Fig. 7; Fig.
11 is a piercing mold assembly drawing for manufacturing a second formed article of the present invention.
12 is a punch configuration diagram of Fig.
13 is a third lower die configuration diagram of Fig.
14 is a conceptual diagram of a method of manufacturing a seat belt pretensioner wheel gear according to the present invention
15 is a configuration diagram of a third formed article of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, which illustrate a method and apparatus for manufacturing a factory safety belt pretensioner wheel gear using high-precision cold forging. FIG. 1 is a conceptual view of a method of manufacturing a seatbelt pretensioner wheel according to the present invention, FIG. 14 is a conceptual view of a method of manufacturing a seatbelt pretensioner wheel gear according to the present invention, and FIG.

As shown in FIGS. 1, 14 and 15, in the method for manufacturing a manufacturing process of a safety belt pretensioner wheel gear using a high-precision cold forging according to the present invention, a preparation step of cutting a round steel bar material to produce a cylindrical blank (B) A first heat treatment step S20 for softening the blank B by annealing heat treatment and a first coating step S30 for coating the softened heat treatment blank B with a coating treatment agent.

Next, in the preliminary forging step S40, the coated cylindrical blank B is forged to form the gear tooth 1 on the outer peripheral portion of the first cylindrical body 5 and the intermediate recessed circular bottom surface portion 3 are formed on the first molding body S1.

Next, in the piercing step S50, the first molded body S1 is placed in the piercing mold, the circular bottom face portion 3 is pierced to form a through groove 13 at the center, and the second cylindrical body 15 is pierced, The second formed body S2 provided with the gear teeth 11 is formed.

Next, a third heat treatment step S60 for annealing and softening the second formed body S2 is performed; A third coating step (S70) for coating the softened heat-treated second formed body (S2) with a coating treatment agent proceeds. The second formed body S2 is cold-forged in the final forging step S80 so that in addition to the through groove 23 formed at the center of the third circumferential body 25 and the gear teeth 21 formed at the outer peripheral portion, The ball groove 27 and the ball groove 27 are formed so that the shape of the groove is gradually increased and decreased along the main portion (inner circumference) And a third supported body S3 provided with a ball supporting stepped surface 27a corresponding thereto.

Fig. 2 is a view showing the assembly of a third formed product forging die of the present invention, Fig. 3 is an upper punch structure of Fig. 2, Fig. 4 is a central counter punch (Lower) configuration diagram of Fig. 2, and Fig. 6 is a configuration diagram of the lower die of Fig.

≪ Third Forging Forging &

2 to 6, an apparatus for manufacturing a work safety belt pretensioner wheel gear using a high-precision cold forging according to the present invention comprises a gear tooth 11 having a mountain and a valley repeatedly formed on the outer circumference of a second circumferential body 15, And the second formed body S2 having the circular through groove 13 formed at the center thereof is forged to form a through groove 23 formed at the center of the third circumferential body 25 and a gear tooth 21 , The groove width is gradually increased and decreased along the inner circumferential portion (inner circumferential portion), and the shape in which the groove width is gradually enlarged and reduced again is repeated so that the ball groove 27 and the ball Is a forging mold 100 comprising an upper punch portion 110 and a lower mold portion 150 for molding a third formed body S3 provided with grooves 27 and corresponding ball supporting stepped surfaces 27a.

2 and 3, the upper punch 110 includes an upper punch holder 111 which is lifted and lowered by a press, and a punch body 115a which is mounted on the upper punch holder 111, A pressing punch 113 on a hollow cylinder formed with a gear tooth 113a on the outer periphery of the punch body 115a and a lower punch 113 formed on the upper portion of the punch body 115a, And a punch 115.

2 and 4 to 6, the lower mold part 170 includes a lower frame part 120 positioned to face the lower part of the upper punch holder 111, And a lower die 130 in which a shaping chamber 131 is formed at the center and a toothed groove 132 is formed in the inner peripheral wall so that the crest and the crest are repeatedly formed corresponding to the gear teeth.

4, the center counter punch 140 of the lower mold part 170 extends upward from the lower frame 120 to the molding chamber 131 while the lower part of the body is supported by the lower frame 120, Thereby forming the ball groove 27 of the step S3.

5, the outer counter punch 150 of the lower mold part 170 supports the lower part of the third formed body S3 (the opposite side of the ball supporting stepped surface 27a) And extruded into the molding chamber 131 and the hollow portion of the lower frame portion 120 so as to be slidable by the central counter punch 140. As shown in FIG. 2, the ejecting means 160 moves the outer counter punch 150 up and down to eject the lower portion of the third formed body S3 by pushing it upward.

 2 and 4, in the center counter punch 140, a second molded body (not shown) is mounted on the upper portion of the center counter punch 140, And the protruding core rod 141 is inserted into the upper core insertion groove 114. The ball groove 27 is formed at a position below the protruding core rod 141, And the ball groove forming protruding protrusion 145 is formed in a shape that gradually increases and then protrudes in a radial direction along the circumference in a shape corresponding to the circumference, .

As shown in FIGS. 2 and 6, the outer counter punch 150 has a shape corresponding to the protruding shape of the ball groove forming protruding protrusion 145 so as to be extensively slidable in the center counter punch 140, And the gear teeth 154 are formed in the outer peripheral portion of the outer counter punch 150 in a shape corresponding to the tooth groove 132 of the lower die 130. [ And can be raised and lowered on the central counter punch 140 at the hollow portion of the lower frame portion 120. The upper surface 150a of the outer counter punch 150 pushes up the lower portion of the third formed body S3 to release the outer counter punch 150 when the ejecting means 160 rises to push up the outer counter punch 150. [

 2, the lower frame part 120 includes an upper punch holder 111 and a lower punch holder 111. The lower frame part 120 includes an upper punch holder 111 and a lower punch holder 111, And a second lower frame 125 which is positioned below the first lower frame 121 and is supported by the support frame. The center counter punch 140 and the outer counter punch 150 are housed in the hollow chamber and the lower face of the center counter punch 140 is supported on the upper portion of the second lower frame 125. The outer counter punch 150 Is smaller than the inner diameter of the middle portion of the hollow chamber 121a to form a clearance space 121a in which the lower extension tab 152 of the outer counter punch 150 can move up and down.

≪ First Forged Body Forging >

8 is a second upper punch configuration diagram of Fig. 7, Fig. 9 is a second counter punch configuration diagram of Fig. 7, Fig. 10 is a second counter punch configuration of the second lower punch of Fig. Fig. The first molded body forging die 200 according to the embodiment of the present invention is formed by forging the cylindrical blank B to form the gear teeth 1 on the outer peripheral portion of the first cylindrical body 5 and the intermediate recessed circular bottom surface A second upper punch portion 210 and a second lower die portion 250 for molding the first formed body S1 provided with the first and second molding portions 3 and 4, respectively.

7 to 10, the second upper punch portion 210 includes a second upper punch holder 211 which is lifted and lowered by a press, a second upper punch holder 211 which is attached to the second upper punch holder 211, A protruding protrusion 213a is formed at the lower end of the second punch body 212 to form the circular bottom surface portion 3 and a mountain and a valley are repeated on the outer circumferential surface of the second punch body 212 And a second upper punch 215 having a gear tooth 213b.

7 to 10, the second lower mold part 170 includes a second lower frame part 220, a second lower die 230, a second counter punch 240, And a second ejecting means (260). The second lower frame part 220 is located opposite to the lower part of the second upper punch holder 211. The second lower die 230 is located at an upper portion of the second lower frame 220 and has a second molding chamber 231 formed at the center thereof. Is formed.

7 to 10, the second counter punch 240 is formed with a gear tooth 241 having a mountain and a valley repeatedly formed on the outer circumferential surface corresponding to the toothed groove 232, and a lower portion of the body is formed in the second lower frame 220 and extends upward to a lower portion of the second molding chamber 231 to support and mold the lower surface of the first formed body S1. The second ejecting means 260 moves the second counter punch 240 up and down to eject the lower portion of the first formed body S1 by pushing it upward.

<Piercing mold for manufacturing second molded article>

Fig. 11 is a piercing mold assembly for manufacturing a second formed article of the present invention, Fig. 12 is a punch construction diagram of Fig. 11, and Fig. 13 is a third lower die construction diagram of Fig. The piercing mold 300 has a through hole 13 formed at the center by piercing the circular bottom face portion 3 after positioning the first formed body S1 in the piercing metal mold, The second formed body S2 provided with the teeth 11 is formed.

As shown in FIG. 11, the piercing upper mold portion is composed of an upper punch holder 311 and an upper punch 315. 12 and 13, the piercing lower mold part includes a lower plate 310 and a piercing lower die 320 located on the upper part of the lower plate 310. As shown in Fig. 13, the lower die 320 for piercing is composed of a seating groove 320a on which the first formed body is seated and a middle piercing hole 321.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but on the contrary, &Lt; RTI ID = 0.0 &gt; and / or &lt; / RTI &gt;

It is to be understood that the appended claims are intended to supplement the understanding of the invention and should not be construed as limiting the scope of the appended claims.

B: blank 5: first circumferential body
1: gear teeth 3: bottom part
13: through groove 15: second circumferential body
11: gear teeth S1, S2, S3: first, second and third formed bodies
25: third circumferential body 23: penetrating groove
21: gear tooth 27: groove
27a: ball supporting step surface 100: forging mold
110: upper punch part 150: lower mold part
11: upper punch holder 115a: punch body
113a: Gear tooth 113: Pressurizing punch portion
114: upper core insertion slot 115a: punch body
115: upper punch 170: lower mold part
120: lower frame part 131: molding chamber
132: tooth groove 130: lower die
140: Central counter punch 150: Outer counter punch
160: ejecting means 141: protruding core rod
145: ball groove forming protruding jaw 153: inner peripheral wall curved surface portion
154: gear tooth type 150a: upper surface
210: second upper punch part 250: second lower die part
200: Forging mold 211: Second upper punch holder
212: second punch body 213a: protruding jaw
213b: gear tooth type 215: second upper punch
170: second lower mold part 220: second lower frame part
231: second forming chamber 232: tooth groove
230: second lower die 241: gear tooth
240: second counter punch 260: second ejecting means

Claims (6)

A method of manufacturing a seat belt pretensioner wheel gear,
Preparing a cylindrical blank (B) by cutting the round steel bar (S10); A first heat treatment step (S20) of annealing and softening the blank (B); A first coating step (S30) of coating the softened heat-treated blank (B) with a coating agent;

The formed cylindrical blank B is forged to form the first formed body S1 having the gear tooth 1 at the outer peripheral portion of the first cylindrical body 5 and the intermediate concave circular bottom face portion 3 Forming a preliminary forging step (S40);

After the first formed body S1 is positioned in the piercing mold, the circular bottom face portion 3 is pierced to form a through groove 13 at the center and gear teeth 11 are formed on the outer peripheral portion of the second circumferential body 15 A piercing step S50 for molding the second formed body S2;

A third heat treatment step (S60) of annealing and softening the second formed body (S2); A third coating step (S70) of coating the softened heat-treated second formed body (S2) with a coating agent;

The second formed body S2 is cold-forged to form a through groove 23 formed at the center of the third circumferential body 25 and a gear tooth 21 formed at the outer circumferential portion and a groove width 21 along the inner circumferential portion The ball grooves 27 and the ball supporting grooves 27 corresponding to the ball grooves 27 are formed so that the shape of the ball grooves 27 becomes larger and the groove width becomes larger and smaller, A final forging step S80 for forming a third formed body S3 provided with the first molded body 27a;
Wherein the step of forming the pretensioner wheel gear comprises the steps of:
The second formed body S2 having the gear teeth 11 regularly formed with the mountain and the valley repeated on the outer circumferential portion of the second circumferential body 15 and the circular through groove 13 formed at the center thereof is forged,
In addition to the through groove 23 formed at the center of the third circumferential body 25 and the gear teeth 21 formed at the outer peripheral portion, the groove width gradually increases along with the inner circumferential portion (inner circumferential portion), then decreases and then the groove width gradually increases A third formed body S3 having two to six ball grooves 27 and a ball supporting stepped surface 27a corresponding to the ball grooves 27 are formed so as to be repeatedly reduced in shape 1. A forging mold (100) comprising an upper punch portion (110) and a lower mold portion (150) for molding;

The upper punch unit 110 includes:
An upper punch holder 111 which is raised and lowered by a press,
A punch body 115a is mounted on the upper punch holder 111 and integrally raised and lowered together with a pressurizing punch 113 on a hollow cylinder formed with gear teeth 113a at the outer periphery of the punch body 115a, An upper punch 115 in which a core upper insertion groove 114 is formed at a lower center,
And,

The lower mold part 170 is formed with a through-
A lower frame part 120 positioned to face the lower part of the upper punch holder 111;
A lower die 130 located at an upper portion of the lower frame 120 and having a molding chamber 131 formed at the center thereof and a tooth groove 132 formed in an inner peripheral wall of the lower frame 120 so as to repetitively repose mountains and valleys corresponding to gear teeth;
A center counter punch 140 which extends upward from the bottom of the body to the molding chamber 131 to form a ball groove 27 of the third formed body S3, ;
The molding space 131 and the lower frame part 120 support the lower part of the third formed body S3 (the opposite side of the ball supporting step face 27a) and are extrapolated to the center counter punch 140, An outer counter punch 150 slidably mounted on the center counter punch 140 at a hollow portion of the center counter punch 140;
And an ejecting means (160) for raising and lowering the outer counter punch (150) and pushing the lower portion of the third formed body (S3) upward to eject the workpiece. Method and apparatus for manufacturing pretensioner wheel gear.
3. The method of claim 2,
A center counter punch 140 that extends upward from the bottom of the body to the molding chamber 131 and upwardly forms a ball groove 27 of the third formed body S3 ,

A circular through groove 13 of the second formed body S2 and a protruding core rod 141 to be inserted into the upper core insertion groove 114 are formed on the upper portion,
The protruding core rod 141 is formed at a position corresponding to the ball groove 27 in a radial direction along the circumference of the protruding core rod 141, The ball groove forming protrusions 145,
And a high-precision cold forging unit.
The method of claim 3,
The outer counter punch 150 is formed so that the inner circumferential wall curved surface portion 153 is concave and convex in a shape corresponding to the protruding shape of the ball groove forming protruding protrusion 145 so as to be extensively slidable in the central counter punch 140 ,
The gear teeth 154 are formed in the outer periphery of the outer counter punch 150 in a shape corresponding to the tooth groove 132 of the lower die 130,
The central counter punch 140 can be elevated from the hollow portion of the lower frame part 120,
When the ejecting means 160 rises to push up the outer counter punch 150, the upper face 150a of the outer counter punch 150 pushes up the lower portion of the third formed body S3 to perform demolding A manufacturing device for a manufacturing process of a safety belt pretensioner using high precision cold forging.
5. The method of claim 4,
The lower frame part 120
A first lower frame 121 having a hollow chamber facing the lower portion of the upper punch holder 111,
And a second lower frame 125 positioned below the first lower frame 121 and supported by the support frame,

The center counter punch 140 and the outer counter punch 150 are housed in the hollow chamber and the lower surface of the center counter punch 140 is supported on the upper portion of the second lower frame 125,

An outer diameter of the middle portion of the outer counter punch 150 is smaller than an inner diameter of the middle portion of the hollow chamber 121a so that a clearance space 121a in which the lower extension chin 152 of the outer counter punch 150 can move up and down is formed Wherein the pre-tensioner and the pre-tensioner wheel gear are mounted on the vehicle body.
The cylindrical blank B is forged to form the first molded body S1 having the gear tooth 1 on the outer peripheral portion of the first cylindrical body 5 and the intermediate concave circular bottom face portion 3, A forging die (200) composed of an upper punch part (210) and a second lower die part (250)

The second upper punch unit 210 includes:
A second upper punch holder 211 which is raised and lowered by a press,
A second punch body 212 mounted on the second upper punch holder 211 and integrally lifted and lowered together,
The second punch body 212 and the second punch body 212. The second punch body 212 has a protruding protrusion 213a for forming the circular bottom face portion 3 at a lower end thereof and a gear tooth 213b having an obtuse- The upper punch 215,
And,

The second lower mold part 170 includes:
A second lower frame part 220 positioned to face the lower part of the second upper punch holder 211;
A second molding chamber 231 is formed at the center of the second lower frame 220 and a second lower portion 231 is formed at an inner peripheral wall of the second molding chamber 231 to form a toothed groove 232, A die 230;
The gear teeth 241 are formed on the outer peripheral surface of the second molding chamber 231 so as to correspond to the tooth groove 232 and the lower portion of the body is supported by the second lower frame 220, A second counter punch 240 extending and forming a lower surface of the first formed body S1;
Second ejecting means (260) for moving the second counter punch (240) up and down so as to push and lower the lower portion of the first formed body (S1) upward;
Wherein the fastening member is made of a high precision cold forging material.

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