JP2013086114A - Press bending device of metal plate and press bending method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press bending device for Mg alloy plate, or the like, and a press bending method using the press bending device, capable of, in a case where a metal plate of low ductility such as Mg alloy plate is locally heated for press bending, heating a bending portion locally and capable of easily exchanging a punch or a die (for example, V-shape punch or V-shape die).SOLUTION: A press bending device for a metal plate 1 includes a bending upper die and a bending lower die. In the press bending device for the metal plate 1, the bending upper die includes an intermediate body 3 which heats a punch 2 by a heater 10 that is incorporated, with the intermediate body 10 and the punch 2 being detachable from each other.

Description

  The present invention relates to a press bending apparatus and a press bending method that perform bending by locally heating a metal plate.

In general, Mg alloy plates mainly composed of magnesium such as JIS standard AZ31 and having an Mg content of 90% by mass or more are lightweight, high strength, and excellent in electromagnetic shielding and heat dissipation. It is attracting attention as a material for housings of electronic devices such as TV cameras.
However, since it is difficult to process the Mg alloy plate, casting is widely performed to obtain a product made of Mg alloy, but the product obtained by casting has a problem that dimensional accuracy is inferior and productivity is low. There is.

Also, as a forming technique other than casting, Mg alloy plates are heated and subjected to press bending, etc. Further, other than Mg alloy plates, for example, duralumin plates with low ductility, Ti alloy plates, high As for difficult-to-work materials such as tensile steel plates, a technique for obtaining a press-bent molded product with good dimensional accuracy is being studied.
For example, Patent Document 1 discloses a technique for performing a bending process while locally heating a bending part of an Mg alloy plate using a punch and a die with a built-in heater. In this technique, a press-formed product is disclosed. When it is necessary to replace the punch and die according to the shape, size, etc., there is a problem in that the wiring between the heater and the power source is removed or connected, and the replacement work of the punch and die becomes complicated. In addition, when bending molded products of various shapes and dimensions, there is a problem that the manufacturing cost increases because it is necessary to incorporate heaters in each of the various types of punches and dies that are exchanged according to the molded products. .

  Further, Patent Document 2 discloses a technique for performing press working while heating the entire Mg alloy plate using a punch and die with a built-in heater. There is a problem that the exchange work of the die becomes complicated and a cost for embedding the heater in the punch and the die becomes high.

JP 2001-105029 A JP 2001-252729 A

  In the present invention, when a metal plate having low ductility such as an Mg alloy plate is locally heated and subjected to press bending, the bending portion can be locally heated and a punch or die (for example, a bevel punch or a bevel die) is used. It is an object of the present invention to provide a press bending apparatus such as an Mg alloy plate that can be easily replaced, and a press bending method using the bending apparatus.

  The inventors of the present invention have intensively studied the prior art for locally heating the Mg alloy plate by a punch with a built-in heater. As long as the Mg alloy plate is relatively thin, even if heat dissipation is high, it takes a short time. Focusing on the fact that it is possible to raise the temperature to a predetermined temperature, it is possible that the temperature can be sufficiently increased to a predetermined temperature without relying on the conventional method of directly heating the Mg alloy plate by a punch with a built-in heater. Then, an attempt was made to heat the punch with an external heat source and indirectly heat the Mg alloy plate with that heat. And when the present inventors experimented on the several Mg alloy board from which board thickness differs, if the board thickness of Mg alloy board is up to about 2 mm, it will locally heat a bending site | part to an appropriate temperature in a short time enough. Based on this knowledge, we have further devised the structure of the bending upper mold. If the punch is attached via an intermediate body with a heater embedded, it is not necessary to incorporate the heater in the punch. Therefore, the manufacturing cost can be greatly reduced, and there is an advantage that only the punch can be easily replaced to cope with the bending of molded products having various shapes and dimensions.

That is, the present invention relates to a press bending apparatus for a metal plate having a bending upper die and a bending lower die, and the bending upper die has an intermediate body for heating the punch by a built-in heater, and the intermediate body and the punch are attached and detached. It is a press bending apparatus of a metal plate that is freely configured.
In the press bending apparatus of the present invention, the lower bending die preferably has an intermediate body that heats the die with a built-in heater, and the intermediate body and the die are preferably configured to be detachable. The metal plate is preferably an Mg alloy plate having a thickness of 0.1 to 2.0 mm, and is provided with preheating means for preheating the metal plate entirely or locally preheating the bent portion of the metal plate. It is preferable.

In addition, the present invention uses the above-described press bending apparatus to bring a punch into contact with a bending portion of a metal plate placed on a die, and to change the bending portion with heat supplied from a heater built in an intermediate body to 200 to This is a metal plate press bending method in which the metal plate is subjected to press bending by heating to 350 ° C.
In the press bending method of the present invention, the metal plate is preferably an Mg alloy plate having a thickness of 0.1 to 2.0 mm. In addition, it is preferable to preheat the metal plate entirely before press bending, or to locally preheat the bent portion of the metal plate, so that the entire surface of the metal plate or the bent portion is 150 to 300 ° C. by the preheating. It is preferable to heat.

  According to the present invention, the bending portion can be locally heated by a simple punch and die without a built-in heater to perform bending processing with good dimensional accuracy, and the punch and die (for example, the bevel punch or the bevel die) can be replaced. Since it can be carried out easily, the production cost is low, and it has an industrially excellent effect for press bending of a metal plate having low ductility such as an Mg alloy plate.

It is a perspective view which shows typically the example of the press bending apparatus of this invention. It is a perspective view which shows typically the other example of the press bending apparatus of this invention. It is sectional drawing which shows the example of the heating part of a metal plate typically. It is a perspective view which shows typically the example which preheats a metal plate.

FIG. 1 is a sectional view schematically showing an example of the press bending apparatus of the present invention, and FIGS. 2 and 3 are sectional views schematically showing other examples of the press bending apparatus of the present invention. The press bending apparatus of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, the press bending apparatus of the present invention includes an upper die 3 and a die 6 having an intermediate body 3 with a heater 10 and a punch 2 detachably mounted in contact with the intermediate body 3. In addition to this, the heat insulating bodies 4 and 8 and the cooling bodies 11 and 12 may be provided as necessary. The heat insulator and the cooling body will be described later.

Next, a specific aspect of this press bending apparatus will be described.
Since the punch 2 at the tip of the bending upper die is mounted in contact with the intermediate body 3 adjacent to the upper stage, if the intermediate body 3 is heated by the built-in heater 10, the punch in contact with the intermediate body 3 2 is also indirectly heated by the heat of the intermediate 3. Therefore, prior to the bending process, first, the punch 2 is indirectly heated to the appropriate temperature for the bending process, for example, 200 to 350 ° C. by the heat of the intermediate body 3. Then, the punch 2 at the tip is brought into contact with the metal plate 1, and the heat of the punch 2 is transferred to the metal plate 1 while maintaining this state for a certain time to heat the metal plate 1 to 200 to 350 ° C. Next, the metal plate 1 is bent by lowering the punch 2 simultaneously with detecting that the metal plate 1 has reached an appropriate temperature of 200 to 350 ° C.

According to such an aspect of the present invention, the time required to bend after the indirectly heated punch is brought into contact with the metal plate 1 varies depending on the plate thickness of the metal plate 1 and the length of the bending portion. However, since it is only 2 to 20 seconds, there is almost no difference compared to the conventional mode in which the metal plate 1 is directly heated, and it can be sufficiently put into practical use.
FIG. 2 shows a mode in which a plurality of intermediate bodies 3 are arranged in the longitudinal direction. According to the mode of FIG. 2, even when the punch 2 is replaced according to the length of the metal plate 1 or the length of the bent portion, only the heater 10 necessary for the intermediate body 3 is switched according to the length of the metal plate 1. It can be handled simply by turning it on, so it is efficient.

  In the bending apparatus of the present invention, the intermediate body 7 including the heater 10 may also be provided in the lower bending mold. Even in this case, although not shown, it is preferable that the intermediate body 3 is divided into a plurality of parts in the longitudinal direction. If the die 6 is detachably mounted in contact with the intermediate body 7, the die 6 can be indirectly heated and the die 6 can be easily replaced. In particular, if the die 6 is indirectly heated, the temperature drop of the metal plate 1 due to contact with the die 6 can be prevented in advance, so that the bending of the metal plate 1 with high heat dissipation, such as an Mg alloy plate, can be performed. It is advantageous.

  FIG. 3 illustrates an embodiment in which an intermediate body 7 including a heater 10 is also provided in the lower bending die, 13a is a heating portion (bending portion) indirectly heated by the punch 2, and 13b is a die. The heating parts indirectly heated by 6 are respectively shown. As described above, since the vicinity of the bent portion of the metal plate 1 is indirectly heated by the die 6, even in the case of the metal plate 1 having high heat dissipation such as an Mg alloy plate, heat dissipation from the bent portion is performed. Since it can prevent as much as possible, the outstanding effect that the metal plate 1 can be bent at the temperature suitable for bending is acquired.

Moreover, since the temperature gradient in the vicinity of the bent portion of the metal plate 1 can be reduced by suppressing the temperature difference between the heating portions 13a and 13b to 100 ° C. or less by indirect heating by the die 6, the warpage of the metal plate 1 can be prevented. It is also possible to obtain an effect of preventing bending with good dimensional accuracy.
The heater 10 incorporated in the intermediates 3 and 7 is not limited to a specific configuration, but a simple configuration that generates heat by energization is preferable because it can be efficiently heated.

  Further, since the punch 2 and the die 6 are detachably attached to the intermediate bodies 3 and 7, respectively, the intermediate body 3 incorporating the heater 10 even when the punch 2 and the die 6 are exchanged according to the shape and size of the bent molded product. , 7 can be exchanged easily, and only the punch 2 and the die 6 can be easily exchanged. Therefore, the present invention can easily cope with bending of various types of general-purpose molded products having different shapes and dimensions. An excellent effect of being able to do so can be achieved.

The means for detachably attaching the punch 2 and the die 6 to the intermediate bodies 3 and 7 is not limited to a specific configuration, but a simple configuration using a key or the like is preferable.
According to the indirect heating of the present invention, since the metal plate 1 can be easily heated to a range of 200 to 350 ° C., it can be applied to bending of an Mg alloy plate having high heat dissipation.
In the case of Mg alloy sheets, bending is difficult if the heating temperature of the bending part is less than 200 ° C, and if the heating temperature exceeds 350 ° C, the bending part of the Mg alloy sheet may partially melt. Therefore, it is not preferable in terms of bending dimensional accuracy.

The present invention can be used for bending difficult-to-work metal plates other than Mg alloy plates, such as duralumin plates having low ductility, Ti alloy plates, high-tensile steel plates, etc., as long as bending is possible within the range of 200 to 350 ° C. It can also be applied to.
In particular, in the case of an Mg alloy plate with high heat dissipation, a thin Mg alloy plate having a thickness of 0.1 to 2 mm is preferable. An Mg alloy plate having a thickness of less than 0.1 mm is not very popular, but if it is too thin, the bent portion may partially melt, so that a thickness of 0.1 mm or more is preferable from a practical viewpoint. In the case of a plate thickness exceeding 2 mm, the Mg alloy plate is not practical because it takes a considerable amount of time to heat to 200 to 350 ° C. due to heat input and heat dissipation due to high heat dissipation. Therefore, when bending such an Mg alloy plate having a thickness exceeding 2 mm, a method of preheating the Mg alloy plate entirely before bending or preheating only the bent portion is employed. If this preheating method is adopted, the plate thickness can be bent up to 5 mm.

The preheating means is not particularly limited, and a plate heater, an induction heating coil, a laser beam or the like can be used. Among them, the induction heating coil 14 as shown in FIG. 5 can preheat only the bent portion uniformly and instantaneously in the thickness direction, and is therefore preferable for performing local preheating.
The preheating of the present invention is also effective in shortening the time for indirectly heating the bending site. If the bending portion of the metal plate 1 is preheated before bending, the time for indirect heating by the punch 2 can be greatly shortened, so that bending can be performed instantaneously while maintaining an appropriate temperature.

Although the preheating temperature in this case depends on the material of the metal plate 1 to be bent, it is preferably in the range of 150 to 300 ° C., which is 50 ° C. lower than the bending temperature, from the viewpoint of thermal efficiency.
In the press bending apparatus of the present invention, since the intermediate bodies 3 and 7 are heated to a high temperature of 200 ° C. to 350 ° C. by the heater 10, the heat insulators 4 and 8 are disposed on the upper stage of the intermediate bodies 3 and 7 from the viewpoint of thermal efficiency. Is preferred. If the heat insulators 4 and 8 are not provided, the entire upper bending die including the punch 2 and the entire lower bending die including the die 6 are heated by the heat of the heater 10, and the heating and cooling are performed. In order to prevent such a situation from occurring, there is a concern that the bending upper die including the punch 2 and the entire lower bending die including the die 6 may be distorted by repeating the above over time. 4 and 8 are preferably arranged.

However, even when the heat insulators 4 and 8 are disposed adjacent to the intermediate members 3 and 7, the heat of the heater 10 is slightly transferred to the entire upper bending mold and the entire lower bending mold as described above. As shown in FIG. 1, in order to prevent such a situation, it is necessary to arrange the cooling bodies 11 and 12 adjacent to the heat insulators 4 and 8, as shown in FIG. preferable.
The cooling tool incorporated in the cooling bodies 11 and 12 is not limited to a specific configuration, but is preferable because a configuration in which a pipe through which cooling water or cooling air circulates can be simply and efficiently cooled. .

  The present invention is preferably applied to, for example, a press brake (commonly referred to as a bevel called a bevel) used for V-bending, but is not limited to this press brake. For example, U-bending or edge of a plate other than V-bending is used. It can also be applied as a bending device such as edge bending for bending.

<Example 1>
A procedure for V-bending a 2.0 mm thick Mg alloy plate 1 (JIS standard AZ31, length 100 mm, width 50 mm) using the press brake shown in FIG. 1 will be described below.
First, prior to the V bending, in order to quickly raise the temperature of the bent portion of the Mg alloy plate 1, 240 suitable for bending by the heater 10 in which the punch 2 and the die 6 are built in the intermediate bodies 3 and 7 in advance. Heat to ° C. Next, as shown in FIG. 1, the Mg alloy plate 1 is placed on the die 6, and the punch 2 heated to 240 ° C. is lowered and brought into contact with the bent portion of the Mg alloy plate 1. Was held and heated indirectly until the bent part of the Mg alloy plate 1 reached 240 ° C. Then, at the same time as detecting that the bending portion reached 240 ° C., the bevel punch 2 was lowered (pressed) to perform V bending.

In the case of Example 1, since the die 6 is also heated to 240 ° C. by the heater of the intermediate body 7, indirect heating of the bending portion can be performed quickly, and there is almost no temperature gradient in the vicinity of the bending portion. There was no warping of the bending part.
When the Mg alloy plate 1 was taken out after V bending and the surface of the bent portion of the Mg alloy plate 1 was observed, no warping or cracking was observed, and V bending with good dimensional accuracy could be performed.

<Example 2>
A procedure for V-bending while preheating the Mg alloy plate 1 (JIS standard AZ31, length 300 mm, width 100 mm) having a thickness of 1.0 mm using the press brake shown in FIG. 1 will be described.
Prior to the V-bending process, the procedure for heating the punch 2 and the die 6 in advance in order to quickly raise the temperature of the bending portion of the Mg alloy plate 1 is the same as that in the first embodiment. The heating temperature is 280 ° C.

  Next, the Mg alloy plate 1 is placed on the die 6, and the preheating portion 15 in which the bending portion of the Mg alloy plate 1 is preheated to 230 ° C. by an induction heating coil 14 as shown in FIG. 4 is formed. Immediately after that, the preheated portion 15 of the Mg alloy plate 1 is moved to the bending portion on the center line of the punch 2 and the die 3, and the punch 2 preheated to 280 ° C. is lowered to move the preheated portion 15 ( The indirect heating was performed until the bent part of the Mg alloy plate 1 reached 280 ° C. Then, at the same time as detecting that the bending portion reached 280 ° C., the bevel punch 2 was lowered (pressed) to perform V bending.

Also in the case of Example 2, since the die 6 was heated to 280 ° C. by the heater of the intermediate body 7, no warping of the bending portion was observed.
When the Mg alloy plate 1 was taken out after V bending and the surface of the bent portion of the Mg alloy plate 1 was observed, no warping or cracking was observed, and V bending with good dimensional accuracy could be performed.
<Example 3>
A procedure for V-bending while preheating a 5.0 mm thick Mg alloy plate 1 (JIS standard AZ31, length 300 mm, width 100 mm) using the press brake shown in FIG. 1 will be described.

Example 3 is an example in which a relatively thick Mg alloy plate 1 having a thickness of 5.0 mm is preheated and subjected to V-bending, and the bending conditions other than the heating temperature of 300 ° C. are set to be the same as those in Example 2. Then, V bending was performed.
When the Mg alloy plate 1 was taken out after V bending and the surface of the bent portion of the Mg alloy plate 1 was observed, no warping or cracking was observed, and V bending with good dimensional accuracy could be performed.

  Therefore, it was confirmed that even the Mg alloy plate 1 having a high heat dissipation property whose thickness was limited to 2 mm could be subjected to V-bending to a thickness of 5 mm if preheating was performed before bending.

DESCRIPTION OF SYMBOLS 1 Metal plate 2 Punch 3 Intermediate body 4 Thermal insulator 5 Punch main body 6 Die 7 Intermediate body 8 Thermal insulator 9 Die main body
10 Heater
11 Cooling body
12 Cooling body
13a Heating part by punch
13b Die heating unit
14 induction heating coil
15 Preheating section

Claims (8)

  In a press bending apparatus for a metal plate having a bending upper die and a bending lower die, the bending upper die has an intermediate body for heating a punch by a built-in heater, and the intermediate body and the punch are configured to be detachable. A press bending apparatus for a metal plate.   2. The metal plate press according to claim 1, wherein the lower bending die has an intermediate body that heats the die by a built-in heater, and the intermediate body and the die are configured to be detachable. Bending device.   The metal plate press bending apparatus according to claim 1 or 2, wherein the metal plate is an Mg alloy plate having a thickness of 0.1 mm to 2.0 mm.   The metal plate according to any one of claims 1 to 3, further comprising preheating means for preheating the metal plate entirely or locally preheating a bent portion of the metal plate. Press bending equipment.   Using the press bending apparatus according to any one of claims 1 to 4, a punch is brought into contact with a bending portion of a metal plate placed on a die, and the bending portion is heated to 200 to 350 ° C by heat of an intermediate. A method of press bending a metal plate, wherein the metal plate is press-bended by indirect heating.   6. The method of press bending a metal plate according to claim 5, wherein the metal plate is an Mg alloy plate having a thickness of 0.1 mm to 2.0 mm.   The method of press bending a metal plate according to claim 5 or 6, wherein the metal plate is preheated entirely before the press bending process, or a bent portion is preheated locally.   The method of press bending a metal plate according to claim 7, wherein the preheating temperature is 150 to 300 ° C.

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