JPH03221235A - Manufacture of hollow member - Google Patents

Abstract

PURPOSE:To manufacture a hollow member by executing ironing to a bottom of a bottomed cylindrical raw material with a punch into a tapered guide part and formed part in a die and further pushing through counter ring. CONSTITUTION:The bottomed cylindrical raw material 31 is abutted on the tapered guide part 40b at upper part of the die hole and pushed downward with the punch 36, and the punch is pushed into the forming hole part 40c at outer face of the die while ironing to closely bring the inner diameter of raw material 31 into contact with the outer face of punch 36. Successively, while abutting lower part of the cylindrical body 32 on the counter ring 42, the punch is further pushed downward to punch the bottom wall 32a of cylindrical body 32. In this case, by setting outer diameter of the punch and inner diameter of the die hole for executing the ironing and the punching to inner and outer diameters of the hollow member, the hollow member having good reduction of area can be obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a method for manufacturing a hollow member by cold forging, and in particular, to a method for manufacturing a hollow member by cold forging, and in particular, a method for manufacturing a hollow member by forming a predetermined cylindrical member by punching a solid material with a die and a punch. (Hollow member) The present invention relates to a method for manufacturing a hollow member.

[Prior Art] As a conventional method for manufacturing a hollow member, there is a method shown in FIGS. 4 and 5, for example. Figures 4(a) to (e)
The manufacturing method shown in ) is called the - air removal method. This construction method begins with block-shaped solid material 1 (fourth
Figure (a)) is fitted into the die hole 3a of the die 3 placed on the base 2, and brought into contact with the counter ring 4 provided at the lower part of the die hole 3a. After that, by punching out the center of the material 1 at once with the punch 5 (see Fig. 4)
b)) The outer diameter of the raw material 1 is cut and processed into a cylindrical body 6 having an inner diameter d (FIG. 4(C)).

Next, this cylindrical body 6 is fitted into the outer surface forming hole 7a of the die 7 having a diameter corresponding to the outer diameter of the final hollow member, and a punch 8 having a diameter corresponding to the inner diameter of the final hollow member is inserted into the cylindrical body 6. The taper part 7b of the outer surface forming hole 7a and the punch 8
(FIG. 4(d)). In this way, the desired hollow member 9 is obtained.

The manufacturing method shown in FIGS. 5(a) to 5(g) is called the backward piercing method. In this construction method, first, the material 11 (Fig. 5(a)) is placed on the die 13 on the base 12.
into the die hole 13a and abut against the counter 14 of the die hole 13a. After this, the material 1 is punched with the punch 15.
The backward extrusion process of step 1 is performed (FIG. 5(b)). In this way, the outer diameter of the raw material 11 is machined into a bottomed cylindrical body 16 having an inner diameter d (FIG. 5(C)). Next, this bottomed cylindrical body 16 is inserted into the die hole 17a of the piercing die 17, a hole is punched in the bottom wall 16a with the punch 18, and the cylindrical body 19 is
(Figure 5(e)). Finally, this cylindrical body 19 is fitted into the outer surface forming hole 20a of the die 20 having a diameter corresponding to the outer diameter of the final hollow member, and a punch 21 having a diameter corresponding to the inner diameter of the final hollow member is inserted into the cylindrical body 19. and is squeezed using the taper portion 20b of the outer surface forming hole 20a and the punch 2 (FIG. 5(f)). In this way, the desired hollow member 22 is obtained.

[Problems to be Solved by the Invention] However, such conventional methods for manufacturing hollow members have the following problems.

In the one-shot method shown in FIG. 4, the entire central part of the material 1 is punched out and scrapped, resulting in a very poor material yield. Furthermore, since punching is performed, the life of the punch 5 is short. Furthermore, since the outer diameter and inner diameter of the cylindrical body 6 are set quite close to the outer diameter and inner diameter of the final hollow member 9,
There is no flexibility in the cross-sectional reduction rate (d2/D2) of the cylindrical body 6 and there is a limit.

For example, the cross-section reduction rate in the air removal method is 15% to 2
It is about 0%.

In addition, in the backward piercing construction method shown in FIG. 5, the outer diameter and inner diameter of the bottomed cylindrical body 16 formed by the backward extrusion process shown in FIG. 5(b) are the outer diameter of the final hollow member 22. Since it is set quite close to the inner diameter, the punch 1
If the tip of the punch 5 is crushed, an error will immediately occur in the outer diameter and inner diameter of the bottomed cylindrical body 16, and as a result, the punch 1
The number of times that the punch 5 can be used is limited, and the life of the punch 15 is short.

Further, as with the one-shot construction method shown in FIG. 4, there is a limit to the cross-sectional reduction rate (d2/D2) of the bottomed cylindrical body 16. Furthermore, in this construction method, since the remaining portion 19a of the bottom wall lea remains at the bottom of the cylindrical body 19 due to the piercing process shown in FIG. 5(d), the final hollow is removed by the ironing process shown in FIG. 5(f). Part 2
There are scratches 2 on the inner wall of No. 2 caused by the remaining portion 19a of the bottom wall 16a.
There is a problem that 2a occurs.

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned conventional problems, and involves preparing a cylindrical body with a bottom and expanding the cylindrical body above the upper part of the die hole of the die. The opening taper guide part is brought into contact with the bottom wall side, and a punch loosely inserted into the cylindrical body is used to press the bottom wall downward, and the outer diameter of the cylindrical body is squeezed by the action of the taper guide part. After the inner diameter of the cylindrical body is brought into close contact with the outer surface of the punch by press-fitting into the outer surface forming hole of the lower part of the die hole, the lower part of the cylindrical body is brought into contact with a counter ring disposed within the lower part of the outer surface forming hole. The hollow member manufacturing method is characterized in that the bottom wall of the cylindrical body is punched by pushing the punch further downward.

[Function] According to this means, after the bottomed cylindrical body is brought into contact with the upwardly expanding tapered guide portion formed corresponding to the outer diameter of the cylindrical body from the bottom wall side, the punch is loosely inserted. It will be done.

Then, the bottom wall of the cylindrical body is pressed by this punch, and the cylindrical body is press-fitted into the outer surface forming hole at the lower part of the die hole while being squeezed by the action of the tapered guide portion. The outer circumferential surface of the press-fitted cylindrical body is squeezed to reach the outer diameter of the final hollow member by the restriction of the outer surface forming hole, and is also tightened to reach the inner diameter of the final hollow member by the tight contact of the outer circumferential surface of the pressing punch. I was forced to squeeze. In parallel with this squeezing, the punch descends, and the cylindrical body pressed by the punch reaches the counter ring disposed at the bottom of the outer surface forming hole, and its bottom wall abuts against the counter ring. Furthermore, the punch is displaced downward while pressing the bottom wall, and the bottom wall of the cylindrical body is punched out. As a result, a hollow member having the required outer diameter and inner diameter is formed.

[Example] Hereinafter, the present invention will be explained based on examples.

1 to 3 are diagrams showing one embodiment of the present invention.

First, to explain the structure, this method for manufacturing a hollow member includes a first step (Fig. 1(a) to (a) to
C)), and a second step (the first Figure (d)
~(g)).

As shown in FIG. 2, the cold forging machine that achieves backward extrusion of the material 31 in the first step includes a die 35 placed on a base 34 and having a die hole 35a, and The material 3 in the die hole 35a is displaced.
1, a presser body 37 that fits into the punch 36 and supports the upper end of the material 31, and a die hole 35a.
A material 31 placed at the bottom of the material and pressed by a punch 36
It is equipped with a solid counter 38 that reversely presses the material from below. The inner diameter D1 of the die hole 35a of the die 35 is larger than the outer diameter of the final hollow member 33 (D+>D), and the outer diameter d1 of the punch 36 is larger than the inner diameter d of the hollow member 33 (d
+ > d).

In addition, the cold forging die that achieves ironing and punching of the bottomed cylindrical body 32 in the second step is placed on the base 39 and has a die hole 40a, as shown in FIG. A punch 41 that moves downward in the die hole 40a to push the cylindrical body 32 into the die hole 40a, and a counter ring 42 disposed at the lower part of the die hole 40a. This countering 42
This allows the bottom wall 32a to be punched out by a punch 41 by pressing the cylindrical body 32 from below, and has a punching hole 42a having the same diameter as the punch 41 on its central axis.

Furthermore, the die hole 40a includes an upwardly expanding tapered guide portion 40b forming the upper part of the die hole 40a, and a tapered guide portion 40b that expands upward.
b, and an outer surface molding hole portion 40c that communicates with the die hole 40a and forms the lower part of the die hole 40a. Taper guide section 40b
is formed so that the angle of inclination is, for example, 10 degrees to 15 degrees, and the diameter of the upper peripheral edge is approximately equal to the outer diameter D1 of the cylindrical body 32. This makes it possible to press fit the cylindrical body 32 fitted into the large diameter hole 40b' communicating with the upper part of the tapered guide part 40b into the outer surface forming hole 4Oc with the punch 41. Further, the inner diameter of the outer surface forming hole 40C is set equal to the outer diameter of the final hollow member 33, and thereby functions to shape the outer surface of the press-fitted cylindrical body 32 to the outer surface of the hollow member 33. It looks like this.

On the other hand, the outer diameter of the punch 41 is set equal to the inner diameter d of the hollow member 33.

Next, the operation of the method for manufacturing a hollow member made of Wt will be explained.

According to the first step, the block-shaped material 31 fitted into the die hole 35a of the die 35 is pressed from above by the punch 36 (FIG. 1(a)).

(b)). The material 31 pressed by the punch 36 is press-fitted below the die hole 35a, and is reversely pressed by the counter 38 below the die hole 35a.

When the punch 36 further presses down the material 31 while the counter 38 is in the reverse-pressing state, the outer part of the material 31 is pushed upward while being in close contact with the inner wall of the die hole 35a and the outer wall of the punch 36. The upper end of the pushed-up material 31 is prevented from moving upward by a presser body 37. As a result, the deformed material 31 is tightly filled between the die hole 35a and the punch 36, and the outer diameter D + having the bottom wall 32a,
A cylindrical body 32 with an inner diameter d+ is formed (Fig. 1(C)
). In this way, by forming the bottomed cylindrical body 32 with an outer diameter D+ larger than the inner diameter d and an inner diameter d+ of the hollow member 33, the cross-sectional reduction ratio (d22/D22) of the cylindrical body 32 can be selected to a certain extent. (e.g. 20% to 30%
>, the life of the punch 36 becomes longer.

The cylindrical body 32 thus formed in the first step is transferred to the second step and placed on the tapered guide portion 40b of the die 40 via the bottom wall 32a (FIG. 1 c)). Thereafter, the cylindrical body 32 on the taper guide part 40b is pressed downward by the punch 41 loosely inserted into the hollow part, and is press-fitted into the outer surface forming hole 4Oc under the guidance of the taper guide part 40b ( Figure 1(e)). This cylindrical body 32 is a punch 41
When the cylindrical body 32 is press-fitted downward into the outer surface forming hole 40c, the outer circumferential surface and inner circumferential surface of the cylindrical body 32 fit into the outer surface forming hole 40c.
c and the outer wall of the punch 41, and the outer diameter and inner diameter of the cylindrical body 32 are shaped to the outer diameter and inner diameter d of the final hollow member 33. Further, after the cylindrical body 32 is press-fitted downward and comes into contact with the upper surface of the counter ring 42, only the punch 41 is displaced downward. At this time, the punch 41 punches out the bottom wall 32a and is inserted into the punched hole 42a of the counter ring 42 (FIG. 1(f)). By this punching process, the bottom wall 32a of the cylindrical body 32 is punched out without leaving any residue, and is discharged from the punching hole 42a as a small amount of scrap. In this way, a hollow member 33 with no scratches on the inner wall and a good yield is formed (FIG. 1(g)). In addition, since the hollow member 33 is formed by squeezing the bottomed cylindrical body 32 formed in the first step, the cross-sectional reduction rate (d2/D2) is 1.
Hollow members 33 of 0% to 15% can be easily manufactured.

[Effects of the Invention] As described above, according to the present invention, a cylindrical body with a bottom is prepared, and the bottom wall is attached to the tapered guide portion that expands the cylindrical body upwardly above the upper part of the die hole of the die. The outside diameter of the cylindrical body is pressed downward with a punch inserted loosely into the cylindrical body from the side, and the outer diameter of the cylindrical body is squeezed by the action of the taper guide, while forming the outer surface forming hole at the bottom of the die hole. After pressing the inner diameter of the cylindrical body into close contact with the outer surface of the punch, the lower part of the cylindrical body is brought into contact with a counter ring disposed inside the lower part of the outer surface forming hole, and the punch is pushed further downward. Since the bottom wall of the cylindrical body is punched out by pushing it forward, the outer diameter of the punch and the inner diameter of the die hole for ironing and punching are set to the inner and outer diameters of the final hollow member. By doing so, a hollow member having a good reduction in area can be obtained. Furthermore, since the bottom wall of the bottomed cylindrical body is punched out to leave the remaining part, there is no damage to the inner wall of the hollow member as in the conventional piercing backward method, and - air vent method It does not produce a large amount of scrap. As a result, it is possible to form a hollow member having a smooth inner wall and a good yield, which is a practically beneficial effect.

[Brief explanation of drawings]

1 to 3 are diagrams showing an embodiment of the method for manufacturing a hollow member of the present invention, and FIGS. 1(a) to 3(g) are process diagrams showing cross sections, and FIG. 3 is a sectional view showing the cold forging die used in the first step, FIG. 3 is a sectional view showing the cold forging die used in the second step of FIG. 1, and FIGS. 4(a) to (e)
FIGS. 5(a) to 5(g) are cross-sectional process diagrams illustrating the conventional method for producing hollow members, namely the one-shot method and the piercing backward method. 31...Material 32...Bottomed cylindrical body 32a...Bottom wall 33...Hollow member 35, 40...Dice 35a, 40a...Dice hole 36, 41...Punch 40b ...Taper guide portion 40c...Outer surface molding hole portion 42...Counter ring 1. : 7F 11 North 1 Figure (d) Jar 5 Figure (b) (f) (C) (9) 2 2a (d) Procedural amendment (voluntary)

Claims (1)

[Claims] A cylindrical body with a bottom is prepared, and the cylindrical body is brought into contact from the bottom wall side with a tapered guide portion that expands above the upper part of the die hole of the die, so that the cylindrical body has free play. The outer diameter of the cylindrical body is pressed down with a punch inserted into the outer surface forming hole at the lower part of the die hole while the outer diameter of the cylindrical body is squeezed by the action of the taper guide. After the inner diameter is brought into close contact with the outer surface of the punch, the bottom of the cylindrical body is brought into contact with the counter ring disposed in the lower part of the outer surface forming hole and the punch is pushed further downward. A method for manufacturing a hollow member, characterized in that the wall is punched out.