JP2005081353A - Detonated pressure forming method and its apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detonated pressure forming method by which the damage on the surface of a forming material caused by over-heating at detonation time, is prevented and also, a high strain formation can be realized, and the restraint of using gunpowder quantity and cost reduction according to the minimization of a facility, are contrived. <P>SOLUTION: When a material to be difficult to form, is formed by using the detonated pressure in water, the formation is performed by separating from a propagating medium for impulse wave and exploding the gunpowder set under opening state to the atmosphere and then, by using the impulse wave in the water generated with this detonated pressure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a molding method and apparatus for a difficult-to-mold material plate using detonation pressure, and more particularly to a development technique for high strain rate molding of a difficult-to-mold material.

  In press molding of automobile body sheets and the like, various methods have been developed to satisfactorily mold difficult-to-form alloy materials with low elongation (see, for example, Patent Document 1). Moreover, in such a method, for example, a method of explosive explosives in the air, an underwater explosion molding method in which explosives are completely immersed in water, and the like have been proposed. Furthermore, an underwater electromagnetic forming method using an underwater shock wave generated by using a high-voltage pulse power supply and abruptly opening it in water has been proposed.

  In each of these methods, when explosives are exploded in the air, the explosives and the molded product are placed at positions facing each other, and the molded product is opposed to the molded product on the opposite side of the molded product. A method of arranging a mold or the like in a state of contact is adopted. In such a method, when explosives are detonated, a detonation wave is generated, which propagates in the air and acts on the molded article, thereby imparting a deformation amount to the molded article. Further, in the underwater explosion molding method in which the above-mentioned explosive is completely immersed in water, the space between the explosive and the molding is completely filled with water, and the above-mentioned position is opposite to the explosive with respect to the molding. A mold or the like is arranged in the same manner as in the air. In this case, the workpiece to be in contact with the mold is decompressed by the atmosphere or a vacuum pump. In such a method, when explosives detonate in water, detonation waves are generated, which propagate into the water and generate underwater shock waves. And this underwater shock wave further propagates in the water and causes the shock to act on the molding. In addition, a compressive force due to expansion of detonation gas acts on the water following the underwater shock wave, thereby generating a force that pushes the water, which acts on the molding and further deforms the molding. In this case, since the explosive is completely submerged in water, the force generated by the expansion of the detonation gas acts on the molding. Moreover, the load speed which acts on a to-be-molded object is as very small as about 1/100-1/1000 of the speed of an underwater shock wave. For this reason, the force resulting from the underwater shock wave can be applied gently, and excellent mold transferability is realized.

  Next, in the underwater electromagnetic forming method, both ends of the power capacitor are immersed in water, and a desired gap is given to the both ends, or both ends are fastened with a thin metal wire. Next, the object to be molded is arranged facing the power capacitor, and a mold or the like is placed in contact with the object to be molded at a position opposite to the power capacitor. The object to be molded that is in contact with the mold faces the air or the decompressed gas. In such a method, the electricity stored in the capacitor between the two electrodes is released at once, thereby generating a shock wave in the water, which acts as an impact force on the object to be molded and gives a required amount of deformation.

JP-A-5-329694 (Claims)

  However, in the method in which explosives are detonated in the air, the surface becomes damaged due to, for example, the molding being heated due to excessive heat applied to the molding due to a high temperature during the explosion. In addition, when explosives are detonated in the air, the generated detonation wave decays rapidly when propagating in the air, so the amount of explosives used must be large, and the practical cost Increase.

  In the underwater explosion method, the molded object is deformed at high speed by an underwater shock wave. However, since the large bubble energy generated by detonation is not diffused and consumed, the force pushing the water generated by releasing the bubble energy is large. For this reason, high strain forming is difficult, and a sufficient amount of deformation cannot be obtained in materials such as 5000 series, 6000 series, 7000 series aluminum alloys, Ti alloys, and Mg alloys that are highly strain rate dependent.

  Further, in the underwater electromagnetic forming method, the intensity of the generated underwater shock wave depends on the voltage and the capacitor capacity. According to experiments, only an underwater shock wave of about 10 to 30 MPa can be obtained at 40 kv-0.125 μF (80 KA instantaneous current), and a large facility is required to obtain a strong shock wave. For this reason, the initial cost and running cost are increased, which is practically uneconomical. In this underwater electromagnetic forming method, work is performed in a state in which high-voltage power is immersed in water, so there is a very high possibility of an electric leakage accident and there is a problem in work safety.

  As described above, each of the conventional techniques has a problem to be solved.

  The present invention has been made in view of the above circumstances, and not only prevents damage to the surface due to overheating of the molded object when detonated, but also realizes high strain molding and suppresses the amount of explosive used. Another object of the present invention is to provide a detonation pressure forming method and apparatus for reducing the cost associated with downsizing of facilities.

  That is, the detonation pressure forming method of the present invention is based on the premise that explosives are detonated and underwater shock waves are used in order to prevent damage to the surface due to overheating of the molded object when detonated. When forming a difficult-to-mold material plate using detonation pressure, explode the explosives that are separated from the shock wave propagation medium and open to the atmosphere, and form using the underwater shock wave generated by the detonation pressure It is characterized by that.

  In such a detonation pressure forming method, it is desirable to selectively use the first wave of detonation pressure for forming. This is especially true in free molding that does not use a shape transfer female die as a mold, and the propagation speed generated by the release of bubble energy after the molded object was formed by detonation waves with a high propagation speed. This is because a force acts on the molded article due to a slow water flow or a shock wave after the secondary wave, which further advances the molding, and in some cases, the molded article may be broken.

  Next, a detonation pressure forming apparatus of the present invention is an apparatus for suitably carrying out the detonation pressure forming method described above, and is an apparatus for forming a difficult-to-form material plate using detonation pressure in water. The gunpowder is separated from the shock wave propagation medium, or at least a part of the gunpowder is submerged in the medium and installed in an open atmosphere state.

  According to the detonation pressure forming method of the present invention, as described above, since the forming process is performed in water, the surface is not damaged due to overheating of the object to be molded when the explosion is initiated. Therefore, the surface of the molding can be made extremely smooth. In addition, when a large impact force generated by an underwater detonation of gunpowder is used for molding, a large bubble energy generated by the detonation is diffused and consumed in the air, so that the force pushing the water following the underwater shock wave is greatly reduced. For this reason, only a high-speed underwater shock wave contributes to shaping | molding of a to-be-molded object, and can achieve high distortion processing. Therefore, a sufficient amount of deformation can be obtained even in materials such as 5000 series, 6000 series, 7000 series aluminum alloys, Ti alloys, and Mg alloys having high strain rate dependency.

In addition, according to the detonation pressure forming apparatus of the present invention, detonation waves propagate in water, so that the strength is not rapidly attenuated. For this reason, the amount of explosives to be used can be suppressed as compared with the prior art. Moreover, according to this apparatus, the intensity | strength of the underwater shock wave obtained compared with the conventional underwater electromagnetic forming method is large. Therefore, downsizing of the facility can be achieved, and as a result, cost and the like can be reduced. In addition, since it is not necessary to immerse high-voltage power in water when using this apparatus, it is possible to prevent electrical leakage accidents and ensure work safety.
As described above, according to the apparatus of the present invention, the detonation pressure molding method of the present invention can be suitably carried out, the surface damage due to overheating of the molding can be prevented at the time of initiation, and Strain molding can be realized, and furthermore, the amount of explosives to be used can be suppressed and the cost can be reduced due to downsizing of the equipment.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments.
FIG. 1 is a side view showing an example of a detonation pressure forming apparatus of the present invention. That is, in the figure, 1 is a mold, 2 is an open pressure vessel disposed above the mold 1, 3 is a partition plate for closing the upper portion of the open pressure vessel 2, and 4 is an explosive container 4a and a cylinder portion. 4b, a detonator arranged in the gap of the partition plate 3, 5 an explosive arranged in the explosive container 4a of the detonator 4, 6 a water as a shock wave propagation medium filled in the open pressure vessel 2, 7 Indicates a plate presser disposed between the mold 1 and the open-type pressure vessel 2. The detonation pressure forming apparatus of the present invention includes members corresponding to the reference numerals 1 to 7 shown above. In addition, the explosive 5 arrange | positioned in the detonator 4 is spaced apart from the water 6 which is a shock wave propagation medium, and is installed in the open state in the upper part in FIG. In addition, the mold 1 can be a normal one, and can also be a shape transfer female die. In addition, although the gunpowder 5 is spaced apart from the water 6 in FIG. 1, at least one part can also be submerged.

Next, the case where the molding object 8 shown by the code | symbol 8 in FIG. 1 is shape | molded using the detonation pressure shaping | molding apparatus of the structure mentioned above is demonstrated.
A plate-shaped object 8 that is a difficult-to-mold material is placed between the mold 1 and the open pressure vessel 2 and at places other than the processing position of the object 8, that is, two places in FIG. It is fixed to the mold 1 with a plate holder 7. In this state, the explosive 5 is detonated after confirming that the explosive 5 is separated from the water 6 that is the shock wave propagation medium and that the explosive 5 is installed in an air release state.

  When detonation is performed in this manner, a detonation wave is generated by the explosive 5 in the detonator 4, and this detonation pressure propagates through the water 6 and is transmitted to the molded object 8, which deforms the molded object into a desired shape. . At this time, since the large bubble energy generated by detonation is diffused and consumed in the air above, the force pushing the water generated by opening the bubble energy is extremely small. For this reason, high strain forming only by the action of shock waves is easy, and sufficient deformation amount can be obtained even in materials such as 5000 series, 6000 series, 7000 series aluminum alloys, Ti alloys and Mg alloys having high strain rate dependence. Can do. In addition, when the apparatus shown in FIG. 1 is used, the generated detonation wave mainly propagates in water, so that its intensity is not abruptly attenuated. Therefore, the amount of explosives to be used can be suppressed as compared with the conventional case, and the practical cost can be reduced. Moreover, according to the apparatus shown in the figure, unlike the conventional underwater electromagnetic forming method, there is no inconvenience such as an increase in cost and an electric leakage accident.

  As described above, the apparatus shown in FIG. 1 can solve the problems of the prior art. In other words, the apparatus can prevent surface damage due to overheating of the workpiece at the time of detonation, achieve high strain molding, and further reduce the cost associated with controlling the amount of explosive used and downsizing the equipment. be able to. Furthermore, in the above apparatus, the first wave of detonation pressure can be selectively used for forming processing. In such a case, the same material is used according to the material of the article 8 to be molded. Even if it exists, since the intensity | strength of the shock wave in water can be selectively changed with the desired degree of processing, it is suitable.

Hereinafter, the present invention will be described more specifically with reference to examples.
FIG. 2 is a side view showing an example of a detonation pressure forming apparatus of the present invention. In the apparatus shown in FIG. 1, the open pressure vessel 2 is made of paper, the partition plate 3 is made of cardboard, and the gap between the open pressure vessel 2 and the plate presser 7 is made of clay. Except for sealing, it has the same structure as the apparatus shown in FIG. In the apparatus shown in FIG. 2, the mold was a cylindrical punch having an inner diameter of 100 mm.

  On the other hand, an aluminum alloy plate (A5052-0, plate pressure 1.0 mm) was used as the molding. Moreover, water was used as the shock wave propagation medium, the water depth was 30 mm, and the upper part was opened. Furthermore, 10 g of SEP manufactured by Asahi Kasei Co., Ltd., in which a powdered pen slit type gunpowder was hardened with a paraffin binder, was used as the gunpowder, and this was installed directly above the water surface in the gunpowder storage unit. Under the above conditions, explosives were detonated to perform molding.

  As a result of the forming process, the overhang height of the aluminum alloy plate was 42 mm. That is, this value is 40% in terms of elongation. Moreover, when this aluminum alloy plate was press-molded by a press-extrusion molding apparatus using a ball head punch, the overhang height was 28 to 29 mm. The overhang height was 42 mm. Therefore, it can be said that by using the apparatus of the present invention, workability equivalent to or higher than that of a steel plate can be imparted to a hard-to-form aluminum alloy plate. FIG. 3 is a photograph of the appearance of the molded product. As shown in the figure, the surface property of the molded product is very good because it is not affected by heat from detonation.

  The detonation pressure forming method and apparatus of the present invention are suitable for forming difficult-to-form aluminum alloy plates that are desired to be applied in recent years due to demands for weight reduction of automobile body sheets.

It is a side view which shows an example of the detonation pressure forming apparatus of this invention. It is a side view which shows the detonation pressure forming apparatus used in the Example of this invention. It is an external appearance photograph of the molded product obtained in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mold 2 ... Open type pressure vessel 3 ... Partition plate 4 ... Detonator 5 ... Gunpowder 6 ... Water 7 ... Board presser 8 ... Molding object

Claims (3)

When molding difficult-to-form material plates using detonation pressure in water,
A detonation pressure forming method characterized by detonating explosives that are spaced apart from a shock wave propagation medium and opened to the atmosphere, and forming using an underwater shock wave generated by the detonation pressure.   2. The detonation pressure forming method according to claim 1, wherein the first wave of the detonation pressure is selectively used for forming processing. An apparatus for forming a difficult-to-form material plate using detonation pressure in water,
A detonation pressure forming apparatus characterized in that the explosive is separated from the shock wave propagation medium, or at least a part of the explosive is submerged in the medium, and is installed in an open atmosphere state.

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