JP2013086097A - PRESS BENDING DEVICE OF Mg ALLOY PLATE AND PRESS BENDING METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press bending device for Mg alloy plate, along with a press bending method using the bending device, capable of locally and evenly heating a bending portion of an Mg alloy plate having a high heat radiation characteristic, and capable of performing press-bending quickly before a temperature of the bending portion drops.SOLUTION: The press bending device for an Mg alloy plate includes: a gripping means 2 which can move vertically and to-and-fro, for transporting an Mg alloy plate 1 by gripping it; an aligning means 3 which can move vertically and to-and-fro, for aligning the Mg alloy plate at a predetermined position; an induction heating coil 4 which locally heats the Mg alloy plate; a moving means 5 capable of advancing/retracting the induction heating coil to-and-fro along length direction of the Mg alloy plate; and a punch 6 and a die 7 which are disposed on an upper surface side and a lower surface side of the Mg alloy plate to face each other.

Description

  The present invention relates to a press bending apparatus and a press bending method for locally bending an Mg alloy plate to perform bending.

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, the Mg alloy plate is heated and subjected to press bending, etc., but a technique for obtaining a molded product of the Mg alloy plate with better dimensional accuracy has been studied earnestly. It is a situation.
For example, Patent Document 1 discloses a technique in which an entire Mg alloy plate is heated in a tunnel heating furnace and then bent, but the Mg alloy plate has a high heat dissipation property. Since the Mg alloy sheet that has been carried out is rapidly cooled and it is difficult to keep the entire sheet at a uniform temperature, there is a problem that when this Mg alloy sheet is bent, cracks occur from a relatively low temperature region. is there.

  Patent Document 2 discloses a technique for performing a bending process while locally heating a bending portion of an Mg alloy plate using a punch and a die with a built-in heater. However, this technique uses a punch or a die. Due to the indirect heating of the Mg alloy plate, there is a problem that it takes a considerable time to uniformly heat the Mg alloy plate in the thickness direction due to the high heat dissipation of the Mg alloy plate and the heat efficiency is poor. Further, since the heater is embedded in the die or the like, there is a problem that the manufacturing cost of the die or the like is high.

JP 2001-71037 A JP 2001-105029 A

  The present invention can locally and uniformly heat a bent part of an Mg alloy plate having high heat dissipation, and can perform press bending quickly without lowering the temperature of the bent part. An object is to provide a press bending apparatus for an alloy plate and a press bending method using the bending apparatus.

  In order to solve the above-described problems of the prior art, the present inventors have conducted extensive studies on a technique for uniformly and locally heating a bent portion of an Mg alloy plate with a simple device. As a result, induction heating with a certain diameter is performed. It has been found that if a coil is used, the bent portion can be heated locally and evenly in the thickness direction. In addition, since the Mg alloy plate has high heat dissipation and needs to be bent quickly after being heated to a predetermined temperature, the present inventors further hold and position the Mg alloy plate based on the above knowledge, The present invention has been devised so that the operation of entering and retracting the induction heating coil and the bending operation of the die and the punch can be performed in quick cooperation.

  That is, the present invention comprises a gripping means that is movable in the vertical and longitudinal directions for gripping and transporting an Mg alloy plate, a positioning means that is movable in the vertical and longitudinal directions for positioning the Mg alloy plate at a predetermined position, and an Mg alloy plate. An induction heating coil for locally heating, a moving means for causing the induction heating coil to enter and retract in the longitudinal direction of the Mg alloy plate, and a punch and a die arranged opposite to each other on the upper surface side and the lower surface side of the Mg alloy plate And a press bending apparatus for an Mg alloy plate.

In the press bending apparatus of the Mg alloy plate of the present invention, the induction heating coil is preferably a pipe having an outer diameter of 4 to 15 mm, and one or two induction heating coils are preferably provided.
In addition, the present invention uses the above-described press bending apparatus to position the Mg alloy plate at a predetermined position, and then on the center line of the punch and the die that are arranged to face each other on the upper surface side and the lower surface side of the Mg alloy plate. Inductive heating coil is inserted into the bending part of Mg alloy plate and heated to a heating width of 5 to 30 mm and a heating temperature of 200 to 350 ° C., then the induction heating coil is moved in the longitudinal direction of the Mg alloy plate and retracted, This is a method for press bending of an Mg alloy plate, in which a heated portion of the Mg alloy plate is subsequently press bent using a punch and a die.

  Further, the present invention does not interfere with a punch and a die that are disposed opposite to each other on the upper surface side and the lower surface side of the Mg alloy plate after the Mg alloy plate is positioned at a predetermined position using the press bending apparatus described above. The induction heating coil enters the position and heats the Mg alloy plate to a heating width of 5 to 30 mm and a heating temperature of 200 to 350 ° C. Next, the induction heating coil is moved in the longitudinal direction of the Mg alloy plate and retracted. This is a method of press bending of an Mg alloy plate in which the heating portion of the Mg alloy plate is moved to a bending portion on the center line of the punch and the die, and the heating portion is press bent.

  According to the present invention, it is possible to locally and uniformly heat a bent part of a highly heat-dissipating Mg alloy plate, and to quickly perform press bending while the temperature of the bent part does not decrease. As a result, it is possible to bend an Mg alloy plate with good dimensional accuracy by preventing the occurrence of cracks and the like.

It is a perspective view which shows the example of the apparatus of this invention typically. FIG. 2 is a side view of the apparatus of FIG. 1. It is a side view which shows the example which mounted Mg alloy plate in die | dye. It is a side view which shows the example which performed the press bending process of the heating part. It is a side view which shows the example which has arrange | positioned the induction heating coil before the punch and die | dye centerline. It is a side view which shows the operation which the induction heating coil, the positioning means, and the punch interlock | cooperated.

  FIG. 1 is a perspective view schematically showing an example of a press bending apparatus of the present invention, FIG. 2 is a side view of the apparatus of FIG. 1, and FIG. 3 is a diagram in which an induction heating coil is retracted behind the positioning apparatus. Fig. 4 is a side view showing an example in which the Mg alloy plate is placed on a die, Fig. 4 is a side view showing an example of press bending of the heating unit, and Fig. 5 is an induction heating coil disposed between the punch and the die. It is a side view showing an example. In FIG. 1, in order to clearly show the positioning means 3, the punch 6 and the die 7 are illustrated with a large gap. 2-5, illustration of the moving means 5 is abbreviate | omitted.

Hereinafter, the present invention will be described with reference to FIGS.
First, an operation mode for positioning the Mg alloy plate 1 at a predetermined position will be described. As shown in FIGS. 1 and 2, the Mg alloy plate 1 is gripped and transported by gripping means 2 (for example, a manipulator), and the end of the Mg alloy plate 1 is placed on the positioning means 3 arranged on the opposite side of the gripping means 2. By contacting, the Mg alloy plate 1 is positioned at a predetermined position. In this case, since the positioning means 3 can move back and forth in the longitudinal direction of the Mg alloy plate 1, by adjusting the position of the positioning means 3 according to the dimensions of the Mg alloy plate 1, the Mg alloy plates having various dimensions. One bending site can be positioned at a predetermined position.

In addition to the role of fixing the Mg alloy plate 1, the positioning means 3 prevents the end of the Mg alloy plate 1 (the side on which the gripping means 2 is not mounted) from dripping down due to heating described later. It also plays a role. Further, the positioning means 3 can also play a role of preventing the occurrence of displacement and sagging of the Mg alloy plate 1 placed on the die 7 when performing press bending.
After positioning the Mg alloy plate 1 at a predetermined position, the induction heating coil 4 is advanced from the back of the positioning means 3 to the front in the longitudinal direction of the Mg alloy plate 1 and stopped at the position of the bent portion of the Mg alloy plate 1. . In the embodiment of FIG. 2, the arrangement position of the induction heating coil 4 is the position of the bending portion and is on the center line of the die 7 and the punch 6. However, in the embodiment of FIG. Are arranged in front of the center line of the punch 6. The aspect of FIG. 5 will be described later. As means for causing the induction heating coil 4 to enter forward, for example, air piston moving means shown in FIG. 1 is used, so that the induction heating coil 4 can be entered instantaneously for about 1 second.

  When the induction heating coil 4 is energized, the bent portion of the Mg alloy plate 1 can be locally heated across the plate width to form the linear heating portion 8. If the width L of the heating unit 8 (hereinafter referred to as the heating width) is less than 5 mm, the heating width L is too narrow. Further, if the heating width L exceeds 20 mm, the heating width L is too wide and it is easy to generate a non-uniform temperature portion in the heating portion 8. The width L is preferably in the range of 5 to 20 mm.

Further, if the heating temperature of the heating unit 8 is less than 200 ° C., the Mg alloy plate 1 is difficult to be deformed, so there is a possibility of cracking. If the heating temperature exceeds 350 ° C., the bending part of the Mg alloy plate 1 Therefore, the heating temperature is preferably in the range of 200 to 350 ° C.
If the outer diameter D of the induction heating coil 4 is less than 4 mm, it is difficult to ensure a sufficient heating width L. If the outer diameter D exceeds 15 mm, heating in the thickness direction is not sufficient. The diameter D is preferably within a range of 4 to 15 mm.

  As the shape of the induction heating coil 4, a pipe-shaped configuration capable of cooling the entire coil by circulating cooling water therein is preferable because it is simple and has good durability. Moreover, as shown in FIG. 1, since the Mg alloy plate 1 can be induction-heated from both the upper and lower sides by arranging the Mg alloy plate 1 so as to be inserted inside the U shape, the thermal efficiency It can be heated to a predetermined temperature instantly for 1 to 3 seconds.

Next, after the Mg alloy plate 1 is heated to a predetermined temperature, the holding means 2 for the Mg alloy plate 1, the moving means 5 for the induction heating coil 4, and the positioning until it is rapidly press-bended with the punch 6 and the die 7. A series of operation modes by means 3, punch 6 and die 7 will be described.
In order to perform press bending with the punch 6 and the die 7, it is necessary to retract the induction heating coil 4 and place the Mg alloy plate 1 on the die 7. Therefore, the induction heating coil 4 is retracted rearward in the longitudinal direction of the Mg alloy plate 1 by the moving means 5 and retracted behind the positioning means 3 so as not to prevent the vertical movement of the Mg alloy plate 1. At the same time, while the gripping means 2 and the positioning means 3 are moved downward together with the Mg alloy plate 1, the punch 6 is also lowered, and the Mg alloy plate 1 is placed on the die 7 as shown in FIG. As shown, since the press bending process can be performed instantaneously, the press bending process can be performed instantaneously for 2 to 3 seconds after the Mg alloy plate 1 is heated.

FIG. 5 shows an example in which the induction heating coil 4 is arranged on the front side of the center line of the punch 6 and the die 7 as an application example of FIG. 2, but this application example is shown in FIG. The arrangement of the heating coil 4 is an improvement in that the punch 6 and the die 7 are heated by the induction heating coil 4 together with the heating of the Mg alloy plate 1 and therefore the thermal efficiency is poor.
In the application example shown in FIG. 5 as well, the heating unit 8 of the Mg alloy plate 1 is moved forward by the positioning unit 3 in conjunction with the retracting of the induction heating coil 4 to the rear in the longitudinal direction of the Mg alloy plate 1 by the moving unit 5. While moving to the bending site on the center line of the punch 6 and the die 7, the Mg alloy plate 1 is lowered and placed on the die 7 at that position. Further, the punch 6 is also lowered to a predetermined position in conjunction with the advancement / lowering of the positioning means 3 and set in a state as shown in FIG. 3, and at the same time, the punch 6 is lowered to the bottom dead center as shown in FIG. , So that press bending can be performed instantaneously. In this manner, by interlocking the retracting of the induction heating coil 4, the advancement / lowering of the positioning means 3, and the lowering of the punch 6, the bending portion of the Mg alloy plate 1 is heated to 2 to 2 as in the embodiment of FIG. 2. Press bending can be performed in an instant of 3 seconds.

Here, FIG. 6 shows an operation mode in which the induction heating coil 4 is retracted, the positioning means 3 is advanced and lowered, and the punch 6 is lowered, and the movement is as shown by the arrows in FIG. is there.
Therefore, after the bent part of the highly heat-dissipating Mg alloy plate 1 is locally and uniformly heated, the press bending process can be quickly performed while the temperature of the bent part does not decrease.

As the gripping means 2, it is preferable to use a manipulator that can freely operate the transport and movement of the Mg alloy plate 1. By using the manipulator, it is possible to perform press bending while the gripping means 2 is mounted on the Mg alloy plate 1 and, after the press bending is completed, the manipulator is operated to easily take out the Mg alloy plate 1. You can also.
In addition, although the example which uses one induction heating coil 4 was shown in FIGS. 1-5, when the heating width L cannot fully be ensured, you may use two induction heating coils 4. FIG. However, if the number of induction heating coils 4 exceeds three, the time required to retract the induction heating coil 4 becomes longer, not only the temperature of the heating unit 8 decreases, but also the heating width L increases, and the temperature of the heating unit 8 increases. Is not preferable, and cracking is likely to occur by press bending, which is not preferable.

  1 to 5 show an example of a press brake (a press brake called a bevel), but the present invention is not limited to the press brake, and the Mg alloy plate may have another shape (for example, a U-shape). Etc.) or when bending the end of the Mg alloy plate into an arc (so-called edge bending).

<Example 1>
Using the press brake shown in FIG. 1, press bending of an Mg alloy plate (JIS standard AZ31, thickness 2 mm) was performed according to the procedure shown in FIGS. The procedure will be described below.
First, the Mg alloy plate 1 is gripped and transported using a manipulator as the gripping means 2, and the end of the Mg alloy plate 1 is brought into contact with an L-shaped stopper used as the positioning means 3 as shown in FIG. The Mg alloy plate 1 was positioned by placing the bent part of the Mg alloy plate 1 on the center line of the punch 6 and the die 7.

  Next, by using an air piston as the moving means 5 shown in FIG. 1, one U-shaped induction heating coil 4 (outer diameter D10 mm) enters from the positioning means 3 side, and as shown in FIG. Stopped on the center line of the die 7. Then, the induction heating coil 4 was energized to heat the Mg alloy plate 1 from the upper and lower surfaces. The heating width L of the heating unit 8 is 15 mm, the heating temperature is 300 ° C., and the heating time is 2.5 seconds.

  Immediately after the heating is finished, the induction heating coil 4 is retracted behind the positioning means 3 by using the moving means 5 and at the same time, the gripping means 2 and the positioning means 3 are moved downward together with the Mg alloy plate 1 as shown in FIG. Then, the punch 6 was also lowered and the Mg alloy plate 1 was placed on the die 7, and then press bending was performed instantaneously as shown in FIG. In this way, after the bending part of the Mg alloy plate 1 was heated by the induction heating coil 4, the bending part was press-bended in 2.5 seconds.

Thereafter, the gripping means 2 was operated to take out the Mg alloy plate 1 and the surface of the Mg alloy plate 1 was observed. As a result, no crack was observed and V-bending with high dimensional accuracy could be performed.
<Example 2>
Using the press brake shown in FIG. 1, press bending of an Mg alloy plate (JIS standard AZ31, thickness 2 mm) was performed according to the procedure shown in FIGS. The procedure will be described below.

First, the Mg alloy plate 1 is gripped and transported using a manipulator as the gripping means 2, and the end of the Mg alloy plate 1 is brought into contact with an L-shaped stopper used as the positioning means 3 as shown in FIG. The Mg alloy plate 1 was positioned by placing the bent portion of the Mg alloy plate 1 in front of the punch 6 and the center line of the die 7.
Next, by using an air piston as the moving means 5 shown in FIG. 1, one U-shaped induction heating coil 4 (outer diameter D10 mm) enters from the positioning means 3 side, and as shown in FIG. It was stopped at the position of the bending site before the die 7. Then, the induction heating coil 4 was energized to heat the Mg alloy plate 1 from the upper and lower surfaces. The heating width L of the heating unit 8 was 10 mm, the heating temperature was 250 ° C., and the heating time was 2 seconds.

  Immediately after the heating is finished, the induction heating coil 4 is retracted behind the positioning means 3 using the moving means 5, and at the same time, the gripping means 2 and the positioning means 3 are advanced together with the Mg alloy plate 1 as shown in FIG. Then, the heating portion 8 of the Mg alloy plate 1 is moved to the bending portion on the center line of the punch 6 and the die 7 and the punch 6 is also lowered while being lowered at that position, so that the Mg alloy plate 1 is moved onto the die 7. Then, as shown in FIG. 4, press bending was performed instantaneously. In this way, after the bending portion of the Mg alloy plate 1 was heated by the induction heating coil 4, the bending bending of the bending portion in FIG. 4 could be performed in 2.7 seconds.

  Thereafter, the gripping means 2 was operated to take out the Mg alloy plate 1 and the surface of the Mg alloy plate 1 was observed. As a result, no crack was observed and V-bending with high dimensional accuracy could be performed.

DESCRIPTION OF SYMBOLS 1 Mg alloy plate 2 Gripping means 3 Positioning means 4 Induction heating coil 5 Moving means 6 Punch 7 Die 8 Heating part

Claims (5)

  A gripping means that can move in the vertical and longitudinal directions for gripping and transporting the Mg alloy plate, a positioning means that can move in the vertical and longitudinal directions for positioning the Mg alloy plate in a predetermined position, and the Mg alloy plate locally Induction heating coil for heating, moving means for causing the induction heating coil to enter and retreat in the longitudinal direction of the Mg alloy plate, and a punch and a die arranged opposite to each other on the upper surface side and the lower surface side of the Mg alloy plate And a press bending apparatus for an Mg alloy plate.   The press bending apparatus for an Mg alloy plate according to claim 1, wherein the induction heating coil is a pipe having an outer diameter of 4 to 15 mm.   3. The press bending apparatus for an Mg alloy plate according to claim 1 or 2, wherein one or two induction heating coils are provided.   After the Mg alloy plate is positioned at a predetermined position using the press bending apparatus according to any one of claims 1 to 3, the Mg alloy plate is disposed opposite to the upper surface side and the lower surface side. An induction heating coil is placed in the bent portion on the center line of the punch and die to heat the Mg alloy plate to a heating width of 5 to 30 mm and a heating temperature of 200 to 350 ° C., and then the induction heating coil is attached to the Mg alloy plate. A method of press-bending an Mg alloy plate, characterized in that the heated portion of the Mg alloy plate is subsequently press-bended using the punch and the die after moving in the longitudinal direction.   After the Mg alloy plate is positioned at a predetermined position using the press bending apparatus according to any one of claims 1 to 3, the Mg alloy plate is disposed opposite to the upper surface side and the lower surface side. An induction heating coil is inserted into a position where it does not interfere with the punch and die, and the Mg alloy plate is heated to a heating width of 5 to 30 mm and a heating temperature of 200 to 350 ° C. Next, the induction heating coil is moved to the length of the Mg alloy plate. The Mg alloy plate press, wherein the Mg alloy plate is moved by retreating, the heating portion of the Mg alloy plate is moved to a bending portion on a center line of the punch and the die, and the heating portion is press-bended. Bending method.

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