JPH0337452B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a method for processing a hexagon socket head bolt having a short cylindrical head with a hexagonal hole formed in the center of a flat end face, with fewer steps, before threading. The present invention relates to a method for forging a material for hexagon socket head bolts that can be manufactured, and a forging device used to carry out the method.

Problems to be Solved by the Prior Art and the Invention In general, the material of a hexagon socket head bolt before threading is processed by pressing a wire rod cut into a certain length between molds using a header in the axial direction. The bolt head is formed by upsetting one end of the wire rod, and a hexagonal hole is formed in the end face of the head using a cold heading method. If the upsetting process is used, excessive upsetting will occur and cracks will occur on the outer periphery of the head, so the upsetting is carried out little by little in two or more preforming processes, and in the final process, the head is formed into the final shape. At the same time, a hexagonal hole was formed in the end face of the head, but this required many different types of molds and multiple steps.
This had the disadvantage that a large header had to be used, increasing the manufacturing cost of the product.

It is an object of the present invention to provide a method for forging a material for a hexagon socket head bolt that eliminates such drawbacks and allows a good product to be obtained with fewer steps, and a forging apparatus used to carry out the method. That is.

Embodiment Hereinafter, an embodiment of the apparatus of the present invention will be described based on the accompanying drawings, and an example of the method of the present invention will be clarified in the explanation of its operation.

In FIG. 1, 1 is a die block fitted into a frame (not shown), and its retreating surface 1a
A ring-shaped cutter is fitted into the fitting hole 6 of a cutter holder 5 which reciprocates between the shearing die 2 and the ejecting die 3 while slidingly contacting the retreating surface 1a. 7 is fitted. Projecting surface 1b of dice block 1
A first die 8 and a second die 10 are fitted at intervals through holding tubes 8a and 10a, respectively. , the wire rod a supplied to the shearing die 2
A molded hole 12 is formed on the inner periphery near the tip of the center hole 11 having a diameter into which the second hole is tightly fitted. In the die 10, a forming hole 15 having a shape that matches the outer circumferential shape of the head of a hexagon socket head bolt is formed on the inner periphery near the tip of a center hole 14 having a diameter into which the wire rod a is tightly fitted. On the inner circumferential surface of 15, vertical stripes forming flat knurlings are formed.

The first die 8 and the second die are mounted on the front surface of a punch holder 16 attached to the tip of a ram that reciprocates back and forth opposite the protruding surface 1b of the die block 1.
Mounting holes 17 and 18 are formed corresponding to the dice 10, respectively, and a mounting hole 1 corresponding to the first die 8 is formed.
A guide tube 20 is fitted into the guide tube 7, and a punch holding tube 21 is fitted into the guide tube 20 so as to be able to freely slide forward and backward, and an abutment member 22 is fitted at the rear end. The rear end of the punch holding cylinder 21 and the abutment member 2
A compression coil spring 23 is installed between the diameter-reducing step portion 2 and the punch holding cylinder 21 is biased to protrude forward due to the elasticity of the spring, and the engagement groove 25 formed on the outer periphery is urged.
The protrusion length is regulated by the engagement with the protrusion 26 on the inner circumferential surface of the guide tube 20, and the tip protrudes from the guide tube 20 by a certain length. A fourth punch 28 is fitted into the first punch 28, and a through hole 30 into which the wire rod a is fitted almost tightly is provided in the center of the first punch 28.
As shown in the enlarged view a in the figure, the opening edge on the tip side of the through hole 30 has a widening angle Y of 160° to 160° toward the tip.
A concave surface 31 with an expanded diameter of 170° is formed, and when the ram reaches the front dead center position,
With the abutment surface 32 of the abutment member 22 in contact with the rear end of the punch holding cylinder 21 , the front end surface of the first punch 28 comes into contact with the first die 8 , and the punch holding cylinder 21 is in contact with the first die 8 . An abutment pin 35 whose rear end can abut against the abutment surface 32 of the abutment member 22 is slidably inserted into the center hole 33, and a abutment pin 35 whose rear end abuts against the abutment surface 32 of the abutment member 22 is inserted into the through hole 30 of the first punch 28. Tsuba 3 that can abut against the tip of pin 35
6, and an upsetting pin 38 having a conical convex surface 37 formed at its tip is slidably fitted therein. An abutment member 40 is fitted at the rear end of the other mounting hole 18 of the punch holder 16, and the punch holding cylinder 41 is fitted with its center hole 43 fitted into the reduced diameter portion 44 of the abutment member 40. The punch holding cylinder 41
The mounting hole 45 at the tip has a flat hitting surface 47 at the tip that comes into contact with the second die 10 when the ram reaches the front dead center position, and a through hole 46 at the center.
A second punch 48 is installed, and a pin 51 having a protrusion 50 at its tip for forming a hexagonal hole is almost tightly fitted into the through hole 46, and its enlarged rear end is inserted into the through hole 46. The protrusion 50 is in contact with the tip of the abutting member 40, and the protrusion 50 is in contact with the striking surface 47 of the second punch.
stands out from

Next, the operation of this embodiment will be explained.

The cutter holder 5 has the wire rod a projected from the shearing die 2 by the feed roller at the solid line position in the figure.
After passing through the center hole of the cutter 7 and hitting a stopper (not shown), the cutter holder 5 moves to the chain line position in the figure, thereby cutting the material b and transporting it to the front of the ejection die 3. b is ejected from the cutter 7 by the ejecting pin 52 of the ejecting die 3, held by the feeding device 53, and fed between the first punch 28 and the first die 8, the ram begins to move forward, and along with this, When the tip of the upsetting pin 38 of the first punch 28 that advances comes into contact with the end surface of the material b, the upsetting pin 38 and the abutment pin 35 move relatively backward, as shown by the chain line in FIG. , the tip of the material b is fitted into the through hole 30 of the first punch 28 and held, and the ram advances further, as shown in FIG.
While the material b is pushed into the center hole 11 of the first die 8, the first punch 28
The tip of the ram contacts the first die 8, and the ram advances further so that the abutment surface 32 of the abutment member 22 touches the abutment pin 35.
When it collides with the rear end, the tip of the upsetting pin 38 touches the material b
is pushed out, and when the rear end of the material b comes into contact with the kick-out pin 54 in the center hole 11 of the first die 8,
When the material b is pressed against the upsetting pin 38, the tip of the material b is crushed in the forming hole 12 of the first die 8, and the ram is pushed forward as shown in FIG. When the dead center position is reached, the conical convex surface 37 of the upsetting pin 38 protrudes from the through hole 30, and the tip of the material b is expanded in the circumferential direction, and the first punch 2
By being pressed by the pressing surface 31 of No. 8, the outer periphery tapers at an angle X increasing in diameter from the center of the shaft toward the tip, as shown in FIG.
A material c is produced in which the peripheral edge of the tip surface forms an obtuse angle Y with respect to the outer circumferential surface, and a conical head d having a recess e at the center of the tip surface is formed. As the material c retreats to the rear dead center position, it is ejected from the first die 8 by the kickout pin 54 of the first die 8, and the ejected material c is transferred to the second punch 48 and the second die 10 by a transfer device (not shown). transferred between.

On the other hand, on the second die 10 side, as the ram moves forward, the tip of the material c is pressed by the protrusion 50 of the pin 51 and pushed into the center hole 14 of the second punch 10, as shown in FIG. When the ram advances further and reaches the front dead center position, as shown in FIG.
0 fits into the forming hole 15 of the second die 10, the material c is pressed against the kick-out pin 55 of the second die 10, and the tip part enters the forming hole 1.
5, the head f of the bolt with a flat knurling formed on the outer circumferential surface is formed, and a hexagonal hole g is recessed to form a product h. It is pushed out from the second die 10 by the kickout pin 55 of the second die 10.

Structure and effects of the invention As specifically explained in the above embodiments,
The method for forging the material of the hexagon socket head bolt of the present invention is as follows:
The shearing process involves shearing a wire rod with a circular cross section that has the same diameter as the shaft of the material of the hexagonal socket head bolt to be manufactured into a certain length, and the process involves holding both ends of the sheared wire rod and upsetting one end so that the outer periphery is at the tip. A preforming step of forming a conical head which has a tapered diameter gradually increasing in diameter and whose peripheral edge of the tip surface forms an obtuse angle with respect to the outer circumferential surface, and a step of striking the center of the tip surface of the conical head and its peripheral edge. The finishing process consists of pressing and forming the finished shape of a short cylindrical head with a hexagonal hole in the center of the flat end surface, and the material of the hexagon socket head bolt to be manufactured is Because we used a wire rod with a circular cross section that has the same diameter as the shaft, there is no need to draw the shaft.Also, because we upset one end while holding both ends of the sheared wire, the upsetting ratio is large. The conical head can be formed in one step without buckling, and since the peripheral edge of the tip of the conical head forms an obtuse angle with the outer circumferential surface, the material will not bend around the peripheral edge during upsetting. It is possible to mold the material into a constant shape by firmly pushing it into place.
Furthermore, the center of the tip of the conical head and its periphery were pressed to form the finished shape of a short cylindrical head with a hexagonal hole formed in the center of the flat end. In addition, the hexagon socket head cap bolt material heading device of the present invention has the effect of being able to form the shape of the end face correctly, and the head of the hexagon socket head bolt material of the present invention has the effect of forming the shape of the end face correctly. A first die having a tapered forming hole whose diameter gradually increases toward the tip is formed on the inner periphery of the side, and a short cylindrical head on the inner periphery of the tip of the center hole into which the wire rod is fitted almost tightly. A second die having a forming hole formed in a shape matching the outer circumferential shape of the die block is arranged in parallel with the die block, and the ram reciprocates back and forth opposite to the die block at a position corresponding to the first die.
A first punch having a through hole formed in the center into which the wire rod is inserted substantially tightly, and a conical concave surface formed on the edge of the hole on the front end side of the through hole is slidable in the direction of movement of the ram, and When the ram reaches the front dead center position, the ram is fitted so that its rear end abuts against the abutment member of the ram and its front end surface comes into contact with the first die, and is urged to protrude forward by spring elasticity. and an upsetting pin having a conical convex surface at the front end and protruding from the concave surface of the first punch when the ram reaches the front dead center position is relatively slid into the through hole of the first punch. A second punch is fitted freely into the ram at a position corresponding to the second die, and has a protrusion forming a hexagonal hole on the tip surface and a pressing surface forming a flat end surface, and a second punch is attached to the ram at a position corresponding to the second die. a feeding device for supplying a wire rod, an ejecting device for ejecting the molded product from the first die and the second die, and a transfer device for transferring the preformed product ejected from the first die to the second die. The main idea is that two punches and two dies can be pressed without changing their corresponding positions.
The above method of the invention can be reliably carried out using a small header.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a sectional view showing the ram advanced to the position where the first punch contacts the first die, and Fig. 3 is the ram at the front dead center position. FIG. 4 is an enlarged sectional view of a portion of FIG. 3. 1: Dice block, 8: First die, 10:
2nd die, 11: center hole (of the 1st die), 1
2: Forming hole (of the first die), 14: Center hole (of the second die), 15: Forming hole (of the second die), 2
8: First punch, 30: Through hole, 31: Concave surface, 3
7: convex surface, 38: upsetting pin, 47: striking surface, 4
8: second punch, 50: protrusion, 53: supply device,
54, 55: Kick out pin.

Claims (1)

[Claims] 1. A shearing process in which a wire rod with a circular cross section having the same diameter as the shaft of the material of the hexagon socket head bolt to be manufactured is sheared to a certain length, and a shearing step in which one end side is held while holding both ends of the sheared wire rod. a preforming step of forming a conical head whose outer periphery gradually expands in diameter toward the tip, and whose peripheral edge of the tip surface forms an obtuse angle with respect to the outer circumferential surface; A material for a bolt with a hexagon socket head, which comprises a finishing process of pressing the center and its periphery to form a finished shape of a short cylindrical head with a hexagon hole formed in the center of a flat end face. Heading method. 2. A first die having a tapered forming hole whose diameter gradually increases toward the tip on the inner periphery near the tip of the center hole into which the wire rod cut to a certain length is almost tightly fitted; A second die, which has a forming hole formed in the inner periphery of the tip of the center hole that fits tightly and has a shape matching the outer circumferential shape of the short cylindrical head, is arranged in parallel to the die block, and is opposite to the die block. A through hole into which the wire rod is substantially tightly fitted is formed in the center at a position corresponding to the first die of the ram that reciprocates back and forth, and a conical concave surface is formed on the edge of the front end of the through hole. The first punch is freely slidable in the direction of movement of the ram, and when the ram reaches the front dead center position, the front end surface is in contact with the abutting member of the ram, and the front end surface is in contact with the first die. The ram is fitted so as to come into contact with the ram, is biased to protrude forward by spring elasticity, has a conical convex surface at the front end, and protrudes into the concave surface of the first punch when the ram reaches the front dead center position. An upsetting pin is inserted into the through hole of the first punch so as to be relatively freely slidable, and a protrusion forming a hexagonal hole on the tip surface and a flat end surface are fitted at a position corresponding to the second die of the ram. a feeding device equipped with a second punch having a pressing surface for forming the wire rod into the first die; an ejecting device ejecting the molded product from the first die and the second die; and an ejecting device ejecting the molded product from the first die. 1. A heading device for a material for a hexagon socket head bolt, characterized in that it is provided with a transfer device for transferring the preformed product to a second die.