JP2001170718A - Hydraulic punching method for cylindrical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic punching method for a cylindrical member by which highly accurate and economical punching is carried out in the same stage as hydraulic forming. SOLUTION: In the punching method performed with a punching punch 1 while pressurizing a liquid in the stage of the hydraulic forming by which the cylindrical member 11 is formed into a prescribed shape by pressurizing the liquid filled in the inside of the cylindrical member 11, this method has a punching operation which is performed by advancing the punching punch 1 after once making the pressure of the liquid in the state of low pressure and hole correcting operation which is performed by retreating the punching punch 1 while increasing the pressure of the liquid or after increasing it and the punching operation and hole correcting operation are performed at the same time as the hydraulic forming of the cylindrical member 11 or successively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a punching method for efficiently forming a hole with high processing accuracy in a cylindrical member by using a hydraulic forming method and a punch.

[0002]

2. Description of the Related Art In recent years, CO ₂
Reinforcement measures are required to reduce weight and improve strength. In response to such demands, hollow cylindrical members are used as vehicle bodies and chassis parts, and there is an increasing movement to apply a hydraulic forming method as a processing method of such cylindrical members. Note that the hydraulic forming method is a method of processing a cylindrical member into a predetermined shape by pressing a liquid filled in the inside of the cylindrical member.

[0003] It is necessary to form a hole for mounting other parts, a hole for positioning, and the like in the hydraulically formed cylindrical member.

Conventionally, such drilling is performed in a separate step after a hollow cylindrical member is hydraulically formed into a predetermined shape. Processing has been performed (Japanese Patent Laid-Open No. 6-292929).

[0005]

However, the above-mentioned method includes a step of hydroforming a cylindrical member into a predetermined shape,
Since the step of punching the formed cylindrical member is performed in a separate step, the cost is increased due to an increase in the cost of tools such as dies.

For this reason, the hydraulic forming and the punching process have been performed in the same process. However, depending on the hydraulic pressure applied to the cylindrical member, the punch and the metal on which the punch slides. There has been a problem that the liquid leaks from a gap with a mold (hereinafter referred to as a "sliding member"). In addition, when the liquid pressure is lowered to prevent the leakage of the liquid, there is a problem that dripping remains around the hole after the punching.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an object to perform high-precision and economical drilling of a cylindrical member by performing a punching process in the same step as hydraulic forming of the cylindrical member. Provide a possible processing method.

[0008]

According to a first aspect of the present invention, there is provided a method for forming a hydraulic hole in a cylindrical member, wherein the liquid filled in the cylindrical member is pressurized to form the liquid into a predetermined shape. In the step of pressure forming, in a hole punching method performed by a hole punch while pressurizing the liquid, the pressure of the liquid is temporarily reduced to a low pressure state, and a hole punching operation performed by moving the hole punch forward; and A hole correcting operation performed by retracting the punch while increasing or increasing the pressure of the liquid, wherein the punching operation and the hole correcting operation are performed by hydraulic forming of the cylindrical member. It is characterized in that it is performed simultaneously or continuously.

According to the present invention, the punching operation performed by advancing the punch is performed while the pressure of the liquid is temporarily reduced to a low pressure, so that the punch can be easily advanced and the punch can be easily punched. During operation, liquid can be prevented from leaking from the gap between the punch and the sliding member of the punch. Further, since the hole correcting operation performed by retracting the punch is performed while increasing or increasing the pressure of the liquid, the sag around the hole generated at the time of the punching operation is increased by the increased liquid pressure. Can be corrected. Furthermore, the hydraulic pressure of the cylindrical member can be simultaneously performed by the increased hydraulic pressure at that time, so that efficient and economical drilling can be performed.

According to a second aspect of the present invention, in the method of the first aspect, the sag correcting means is formed in a punched portion near the tip of the punch. It has features.

According to the present invention, the sag correcting means formed at the punched portion near the tip of the punch punch corrects sagging at the periphery of the hole generated during the punching operation when the punch is retracted. Act like so. As a result, the machining accuracy of the hole can be further improved in combination with the correction of the sag by the liquid pressure at the time of the subsequent hole correcting operation.

According to a third aspect of the present invention, in the method of the second aspect, the sag correcting means has an inverse tapered surface that becomes larger toward the tip. Have.

According to the present invention, since the sagging correction means has an inverted tapered surface which becomes larger toward the tip, the tip of the punched portion formed by the inverted tapered surface is used when the punching hole retreats. It acts to hook and pull back the sag around the hole generated during the hole punching operation, thereby correcting the sagging. As a result, the machining accuracy of the hole can be further improved in combination with the correction of the sag by the liquid pressure at the time of the subsequent hole correcting operation.

According to a fourth aspect of the present invention, in the method of the second aspect, the sag correcting means is a groove provided in a circumferential direction.

According to the present invention, since the sagging correcting means is a groove provided in the circumferential direction, when the punching hole retreats, the groove is used to remove the sag around the hole generated at the time of the punching operation. It works by hooking and pulling back to correct the resulting sagging. As a result, the machining accuracy of the hole can be further improved in combination with the correction of the sag by the liquid pressure at the time of the subsequent hole correcting operation.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view for explaining a process showing an example of a method for boring a hydraulic hole in a cylindrical member according to the present invention. In the hydraulic hole punching method of the present invention, in the step of pressurizing the liquid filled in the cylindrical member 11 to hydraulically form the cylindrical member 11 into a predetermined shape, the hole is formed while pressurizing the liquid. This is a method for punching a cylindrical member by a punch 1. The punching process, which is a feature of the present invention, is shown in FIG.
The processing is performed in the order from (a) to FIG. 1 (c).

FIG. 1A shows the positional relationship between the punch 1 and the cylindrical member 11 before the punching. The punch 1 together with the sliding member 10 on which the punch 1 slides is arranged so as to contact the outside of the hollow cylindrical member 11. The punch 1 to be arranged is pressed and held from the outside to the inside of the tubular member 11 at a pressure similar to the hydraulic pressure P1 applied to the inside of the tubular member 11. O-ring 9
Is provided. The O-ring 9 is used for the punch 1
When the head moves forward or backwards, the gap between the punch 1 and the sliding member 10 is sealed to prevent the pressurized liquid from leaking. At this time, the cylindrical member 11
Is, even if it has already been hydraulically molded into a predetermined shape,
It may be before it is hydraulically formed into a predetermined shape.
Prior to being subjected to hydroforming, as described later, it can be subjected to hydroforming at the same time as punching.

FIG. 1B shows a mode in which the punch 1 is advanced to perform a punching operation. The punch 1 is advanced by temporarily setting the liquid pressure inside the tubular member 11 to a low pressure P2. By setting the hydraulic pressure to a low pressure state, the punch 1 can be easily advanced even with a small force. The cylindrical member 11 is a punch 1
It is punched out by the advance of the hole. The size of the hole is the same as the size of the tip of the punched portion 8 of the punch 1.

In performing the punching operation, a constant pressure P2 is applied to the liquid even if the pressure is low, so that the dripping 7 generated in the hole peripheral portion 6 of the punched cylindrical member 11 is removed. The size can be reduced.

FIG. 1C shows a mode in which after the punching operation, a hole correcting operation for retreating the punch 1 to adjust the hole shape is performed. The retraction of the punch 1 is shown in FIG.
After the hole punching operation shown in (1), the pressure is increased while or after the pressure of the liquid is increased. Therefore, the pressure of the liquid may be increased simultaneously with the retraction of the punch 1 or after the punch 1 is retracted to a predetermined position.

By increasing the pressure of the liquid, the dripping 7 of the peripheral portion 6 of the hole generated during the punching operation is removed from the sliding member 1.
It can be corrected so as to be pressed against the contact surface 13 on the side of the cylindrical member 11 of No. 0. As a result, it is possible to obtain the cylindrical member 11 having the hole whose peripheral portion 6 is corrected cleanly.

When the hydraulic forming of the tubular member 11 has already been performed, it is preferable that the punching is performed continuously after the hydraulic forming of the tubular member 11.
That is, when the cylindrical member 11 is hydraulically formed, the punch 1 is arranged as shown in FIG. 1A, and after the hydraulic forming, the punches 1 are successively arranged as shown in FIGS. The holes are punched in the order of c). On the other hand, when the hydraulic forming of the cylindrical member 11 has not been performed yet, first, FIGS.
The hole punching operation is performed in this order, and then the hydraulic pressure is increased, so that the hole correcting operation shown in FIG. 1C can be performed simultaneously with the hydraulic forming.

The advance and retreat of the punch 1 may be performed mechanically or by increasing or decreasing a fluid pressure such as air pressure, water pressure, or hydraulic pressure, and is not particularly limited. At this time, the fluid pressure of the punch 1 and the cylindrical member 1
The punch 1 can be moved forward or backward by a relative difference from the liquid pressure inside the punch 1. For example, in FIG. 1A, the fluid pressure of the punch 1 is in balance with the fluid pressure P1, and in FIG. 1B, the fluid pressure of the tubular member 11 is once in a low pressure state ( When the pressure becomes P2), the punch 1 with relatively increased pressure moves forward to perform a punching operation. In FIG. 1C, the hydraulic pressure of the cylindrical member 11 increases. Then, the punch 1 whose pressure is relatively reduced retreats, and the hole correcting operation is performed. Note that, as described above, the hydraulic forming of the tubular member 11 can be performed at the same time as the hole correcting operation in FIG.

As described above, the hydraulic hole punching method of the present invention utilizes the increase and decrease of the hydraulic pressure used in the hydraulic forming of the tubular member 11 and performs the same steps as the hydraulic forming. , Simultaneously with or subsequent to the hydroforming. As a result, the process can be simplified and the cost of tools such as dies can be reduced.

Next, a description will be given of a punching method performed by a punch having a different shape.

FIG. 2 is a cross-sectional view for explaining a process showing an example of a hydraulic pressure punching method using a punch 2 having a shape different from that of the punch 1 shown in FIG. In the punch 2, the punched portion 8 near the front end is formed by an inverted tapered surface 4 that becomes larger toward the front end.

As shown in FIG. 2A, a sag 7 is formed in the inner peripheral portion of the cylindrical member 11 at the peripheral portion 6 of the cylindrical member 11 after the punching operation. The punch 2 has a punch 8
As shown in FIG. 2 (b), at the time of retreat after the punching operation, the sag 7 is hooked on the tip of the punched portion 8 and the sliding is performed. The moving member 10 can be pulled back to the contact surface 13 side. Therefore, the punched portion 8 formed by this inverted tapered surface
Since the tip of the hole acts as a sagging correcting means, the hole correcting operation performed by increasing the liquid pressure can be further facilitated, and the hole can be corrected to a more beautiful hole shape.

The taper near the tip of the punch 2 is usually preferably about 1/5 to 1/20, but can be appropriately set depending on the material and thickness of the cylindrical member 11. Further, the size of the sag 7 generated is smaller as the hydraulic pressure during the punching operation is higher, and is larger as the hydraulic pressure is lower.
It is preferable to set the taper of the punch 2 in consideration of such circumstances. In addition. The tip of the punch 8 of the punch 2 has the same diameter as the outside diameter of the punch 8 so that the tip of the punch 8 can slide back and forth within the sliding member 10.

FIG. 3 is a cross-sectional view for explaining a process showing an example of a hydraulic hole punching method using a hole punch 3 having a different shape. The punch 3 has a punched portion 8 near the front end provided with a circumferential groove 5.

The punch 3 shown here operates similarly to the punch 2 shown in FIG. That is, the punch 3 can hook the generated dripping 7 into the groove 5 and pull it back to the contact surface 13 side of the sliding member 10 when the punch 3 moves backward after the punching operation. Therefore, the grooves 5 provided in the circumferential direction
Acts as a sagging correction means, so that the hole correction operation performed by increasing the hydraulic pressure, and as a result, the hole correction operation by increasing the hydraulic pressure can be more easily performed, and to a more beautiful hole shape. Can be corrected.

The width and depth of the groove 5 provided in the punch 3 are appropriately set according to the material and thickness of the cylindrical member 11. Further, it is preferable that the position where the groove 5 is provided is appropriately set depending on the stroke length for moving the punch 3 forward, the thickness of the tubular member 11 and the like. In addition, dripping 7
Similarly, as described above, the size of the groove is smaller as the liquid pressure during the hole punching operation is higher, and is larger as the liquid pressure is lower. Therefore, it is preferable to set the position and shape of the groove in consideration of such circumstances.

As the cylindrical member 11 used in the present invention, an aluminum alloy is usually used, but the kind of the alloy is not particularly limited. Furthermore, since the hole punching method of the present invention is performed in a generally used hydraulic forming step, the conditions for the hole punching, that is, the type of the fluid and the hydraulic pressure are determined by the hydraulic forming apparatus. Within the general conditions of For example, the hydraulic pressure is about 500 to 1500
It is performed in the pressure range of the atmospheric pressure.

[0034]

As described above, according to the hole forming method of the first aspect, the hole forming operation including the hole forming operation and the hole correcting operation can be performed simultaneously with or simultaneously with the hydraulic forming of the cylindrical member. Since the pressing can be performed continuously, efficient and economical punching can be performed. At the time of the punching operation, the liquid pressure temporarily becomes a low pressure state, so that the punch can be easily advanced and the leakage of the liquid can be prevented. In addition, at the time of the hole correction operation, the sagging generated at the time of the hole punching operation is corrected by the increased hydraulic pressure,
The hole shape can be made clean and the processing accuracy can be improved. Furthermore, since hydraulic forming and punching can be performed by the same molding die, tool cost can be reduced, and this is an extremely effective method.

According to the second aspect of the present invention, when the punch is retracted, the sag correcting means formed near the front end of the punched portion of the punch is straightened so as to pull back the generated sag. Accordingly, the hole accuracy can be further improved in combination with the correction of the sag due to the liquid pressure at the time of the hole correction operation thereafter.

According to the hole punching method of the third and fourth aspects, when the hole punch is retracted, the reverse taper surface or the groove formed at the tip of the punched portion of the hole punch causes the generated dripping to occur. Since the hook is pulled back to correct the sagging, the hole accuracy can be further improved in combination with the sagging correction by the liquid pressure during the subsequent hole correcting operation.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a process showing an example of a hydraulic pressure punching method for a cylindrical member of the present invention.

FIG. 2 is a cross-sectional view for explaining a process showing an example of a hydraulic pressure punching method using a punch of another shape.

FIG. 3 is a cross-sectional view for describing a process showing an example of a hydraulic pressure punching method using a punch of another shape.

[Explanation of symbols]

 1, 2, 3 hole punch 4 tapered surface 5 groove 6 hole peripheral portion 7 sag 8 punched portion 9 O-ring 10 sliding member 11 cylindrical member 12 punching scrap 13 contact surface

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Kanamori 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Hisao Tanigawa 2-3-3 Shiba 2-chome, Minato-ku, Tokyo Mitsubishi Aluminum Stock In-company (72) Inventor Kimio Ito 194 Chifuku, Susono City, Shizuoka Prefecture Mitsubishi Aluminum Co., Ltd. Chifuku Factory F-term (reference) 4E048 KA02 KA09

Claims (4)

[Claims] 1. A piercing process performed by a piercing punch while pressurizing a liquid in a step of pressurizing a liquid filled in a cylindrical member and hydraulically forming the cylindrical member into a predetermined shape. In the method, once the pressure of the liquid is reduced to a low pressure state, the punching operation is performed by advancing the punch, and the pressure of the liquid is increased or increased, and then the punch is retracted. A hole correcting operation to be performed, wherein the hole punching operation and the hole correcting operation are performed simultaneously or continuously with the hydraulic forming of the cylindrical member. Method. 2. The method according to claim 1, wherein a sag correcting means is formed in a punched portion near a tip of the punch. 3. The method according to claim 2, wherein the sagging correction means is a reverse tapered surface that becomes larger toward the tip. 4. The method according to claim 2, wherein the sag correcting means is a groove provided in a circumferential direction.