JPH0847727A - Method for forming vessel with step - Google Patents

Abstract

PURPOSE:To provide a method capable of forming a vessel with a step whose large diameter is more than a specific time of the wall thickness and whose small diameter is under than the half of the large diameter inexpensively by one stage forming. CONSTITUTION:This forming method of a vessel with a step is an opposed hydro-static forming method that a blank 1 is set on a die 3 of a ring shape and formed in a state of applying a suitable blank holding force by using a punch 2 formed in an article shape and pressing the blank 1 inside a hydraulic pressure controlled water room 5. The method consists of a 1st stage that the opposed hydraulic pressure is made to the pressure of forming a reverse bulging of the blank in the initial stage of a punch stroke, a 2nd stage that the opposed hydraulic pressure is made into the pressure of matching the considerable part of the blank other than the part with the step along the punch 2 near the final stage of the punch stroke, and a 3rd stage that the opposed hydraulic pressure is made into the pressure of matching all the blank 2 along the punch 2 in the final stage of the punch stroke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a stepped container.

[0002]

2. Description of the Related Art Conventionally, when molding a stepped container having a large diameter of 30 times or more of the plate thickness and a small diameter of 1/2 or less of the large diameter, spinning (spatular drawing) or multistage molding by pressing is performed. It was

[0003]

When molding a stepped container having a large diameter of 30 times or more the plate thickness and a small diameter of 1/2 or less of the large diameter, spinning is used in a small-volume product.
In the case of spinning, in the case of a product having a large diameter, the man-hours are large, the repeatability of the molding is not so good, and the man-hours are required for the adjustment in the post-process, which is not suitable for the medium-volume production and the mass production.

On the other hand, in press molding, wrinkles and cracks are generated and molding cannot be carried out unless multiple molding steps are applied. Again, the number of man-hours becomes large, and it is necessary to make many dies.
In terms of cost, it was not suitable for low-volume production and medium-volume production.

On the other hand, counter-hydraulic molding is widely known as a molding method suitable for molding a thin plate while reducing the cost of the mold. The large diameter is 30 times or more the plate thickness, and the small diameter is the large diameter. 1 / of
It was also difficult to form a stepped container having a number of steps of 2 or less in one step because of cracks and wrinkles occurring on the small diameter side that first contacts the blank. It is an object of the present invention to provide a counter hydraulic forming method capable of solving the above problems.

[0006]

[Means for Solving the Problems]

(First Means) A method for forming a stepped container according to the present invention is
Counter-hydraulic molding in which a blank is set on a ring-shaped die, and the blank is pushed into a hydraulic chamber whose fluid pressure is controlled using a punch with a product shape, with a proper wrinkle holding force being applied. In (A) in the initial stage of the punch stroke, in the first stage where the counter hydraulic pressure is set to a pressure at which the blank can be overhanged, and (B) in the vicinity of the final stage of the punch stroke, the counter hydraulic pressure is changed to that of the blank. In the second stage where the pressure is set so that a considerable portion other than the stepped portion can be moved along the punch, and (C) in the final stage of the punch stroke, the counter hydraulic pressure is set so that the entire blank is moved along the punch. It is characterized in that it comprises a third stage for obtaining a pressure that can be achieved.

(Second Means) In the method for molding a stepped container according to the present invention, in the first means, a punch tip portion made of a soft elastic body, a spring for attaching the punch tip portion to the punch, and A punch having a connecting pin is used.

[0008]

The molding method of the present invention performs the following functions when molding a stepped container having a large diameter of 30 times or more the plate thickness and a small diameter of 1/2 or less of the large diameter. On the small diameter side where the punch and the blank first come into contact with each other, the ratio of the blank to the initial outer diameter is smaller than the maximum drawing ratio.

In counter-hydraulic molding, molding is possible to some extent because of improved lubrication of the flange portion and increased slippage at the contact portion between the punch and the blank, but again, deep containers cannot be molded.

On the other hand, if the tip of the punch on the small diameter side is hydraulically moved according to the forming force, the stress applied to the tip of the punch can be controlled and cracking can be prevented.

Further, since the punch tip is made of an elastic body so that the shape of the punch tip changes depending on the pressure, the place where the stress concentrates (usually the point where the punch and the blank come into contact) is liquid. It can be controlled to change with pressure. Therefore, cracking can be prevented.

In the molding of a stepped container having a small plate thickness, the plate is squeezed into a die in a free state at the initial stage of molding, so that a compressive force is applied in the circumferential direction to generate a body wrinkle.
In the counter-hydraulic molding, as shown in FIG. 3, the counter fluid pressure causes the blank to be stretched upside-down and swelled. This acts as a bead and can prevent wrinkles from occurring.

Using the punch portion which is a feature of the present invention,
Since there is a margin in the processing conditions regarding cracks due to the above-described action, it is also possible to prevent wrinkles because a counter hydraulic pressure sufficient to prevent body wrinkles can be applied. With the above operation, the stepped container can be accurately molded in one step.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention is shown in FIGS. 1 to 3 show the structure of the mold used for molding and the blank 1 during molding.
The schematic diagram of the deformation state of is shown. 1 is a blank, 2 is a punch, 3 is a die, 4 is a wrinkle holder, 5 is a water chamber, 6 is a punch tip, 7 is a spring, 8 is a connecting pin, 9 is an inner ram, 10 is an outer ram, and 11 is a retainer. Are shown respectively. The press head, press slide, press frame, etc. are not shown.

FIG. 4 shows the relationship between the counter hydraulic pressure and the wrinkle holding force and the stroke during molding. The material of the first embodiment is
It is an aluminum alloy (A605109), and the product shape has a large diameter: 525 mm, a small diameter: 220 mm, a depth: 160 mm, and a plate thickness: 2.5 mm.

The small diameter side is cut off after molding and joined to the pipe. The initial outer diameter of the blank is 760 mm. Hydraulic oil was used as the counter liquid, and the hydraulic pressure was controlled by adjusting the relief valve of the hydraulic pump.

The press used was a 2000 ton double-acting press. At the tip of the punch 2, 20 springs 7 (spring constant: 6
(0 kgf / mm) and the connecting pin 8 attached the punch tip 6 between the punch 2 and the blank 1.

A gap of 15 mm was provided between the punch tip 6 and the punch 2. The punch tip 6 is made of a soft elastic body (for example, urethane rubber). The molding was performed according to the following procedure.

The blank 1 is placed on the die 3, the outer ram 10 is lowered, and the wrinkle holding force shown in FIG. 4 is applied. In this state, the punch 2 attached to the inner ram 9 is lowered to push the blank 1 into the water chamber 5. The counter hydraulic pressure at this time is shown in FIG.

In FIG. 1, the stroke of the punch 2 is about 50 mm.
4 shows the deformation of the blank 1 in the state (state of FIG. 4A) (first stage). The counter hydraulic pressure at this time is about 1 kgf.
It was / cm ² , but it was possible to prevent the wrinkles of the body from being generated because the reverse protrusion was sufficiently performed. The punch tip 6 at this time is raised by about 3 mm.

FIG. 2 shows a deformed state (state B of FIG. 4) of the blank 1 when the punch 2 is pushed to a stroke (about 180 mm) at the almost final stage. The counter hydraulic pressure is about 30 kgf / cm ² (second stage). The blank 1 is along a considerable part of the punch 2, but the stepped part is not yet fully along. At this time, the punch tip 6 is raised by about 9.5 mm.

FIG. 3 shows the deformation of the blank 1 in the state where the punch 2 is stopped and the counter hydraulic pressure is increased to 200 kgf / cm 2 (state C in FIG. 4) (third stage). The blank 1 was found to be well along the punch 2. The punch tip 6 is about 50 kgf / cm ² and the punch 2
Since the blank 1 did not flow between the punch 2 and the punch tip portion 6, the scratch was not seen at all. Further, finally, since the punch 2 having a product shape can be perfectly followed, the molding precision on the inner surface side, which is important as a container, was extremely good.

As described above, by controlling the counter hydraulic pressure and the wrinkle pressing force and the punch stroke, and by attaching the punch tip portion 6 which is linked to the counter pressure and moves to the tip of the punch, conventionally, cracks and body wrinkles are formed. Therefore, a stepped container that could not be molded in one step can be molded and processed in one step, and the number of man-hours can be reduced.Because only a small number of molds are required, the cost can be greatly reduced and the manufacturing cost can be reduced. It was

[0024]

Since the present invention is configured as described above, the effects described below can be obtained. (1) Since cracking and wrinkling of the body can be prevented, a multi-stage container can be molded in one step without employing a multi-stage press molding method. Therefore, the number of molding steps can be reduced. (2) Since counter-hydraulic molding is used, even when molding a stepped container having a complicated shape, only the punch is processed into a complicated shape, and the die / wrinkle holder may be a simple ring-shaped product. Therefore, the die production cost can be reduced. (3) In the final stage of molding, the punch is machined into a product shape by hydraulic pressure. Therefore, even in the case of uneven deformation such as anisotropy of the plate, the molding accuracy of the inner surface shape can be made extremely high.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a mold according to a first embodiment of the present invention and a schematic diagram of deformation of a plate (state of A in FIG. 4).

FIG. 2 is a configuration diagram of a mold according to the first embodiment of the present invention and a schematic diagram of deformation of a plate (state of B in FIG. 4).

FIG. 3 is a configuration diagram of a mold according to the first embodiment of the present invention and a schematic diagram of deformation of a plate (state of C in FIG. 4).

FIG. 4 is a transition diagram of the punch stroke, the counter hydraulic pressure, and the wrinkle pressing force according to the first embodiment of the present invention.

[Explanation of symbols]

 1 ... Blank, 2 ... Punch, 3 ... Die, 4 ... Wrinkle retainer, 5 ... Water chamber, 6 ... Punch tip, 7a, 7b ... Spring, 8 ... Connecting pin, 9 ... Inner ram, 10 ... Outer ram, 11 … Retainer.

Front Page Continuation (72) Inventor Takahiro Ota 2-1-1 Niihama, Arai-cho, Takasago-shi, Hyogo Mitsubishi Heavy Industries Ltd. Takasago Laboratory

Claims (2)

[Claims] 1. A blank (1) is set on a ring-shaped die (3) and is hydraulically controlled by using a punch (2) having a product shape with a proper wrinkle holding force being applied. In the counter-hydraulic molding in which the blank (1) is pressed into the water chamber (5), (A) In the initial stage of the punch stroke, the counter-hydraulic pressure is set to a pressure at which the blank can be overhanged. (B) In the vicinity of the final stage of the punch stroke, the counter hydraulic pressure is used to punch a considerable part other than the stepped part of the blank (2).
In the second stage, and (C) in the final stage of the punch stroke, the opposing hydraulic pressure is the third stage, in which the entire blank can be moved along the punch (2). A stepped container forming method comprising: 2. Use of a punch (2) comprising a punch tip (6) made of a soft elastic material, a spring (7) for attaching the punch tip to the punch and a connecting pin (8). The method for forming a stepped container according to claim 1, wherein: