JP5942437B2 - Electric heating method, electric heating device and hot press molding method - Google Patents

Description

  The present invention relates to an energization heating method and an energization heating apparatus for heating a conductive plate-like workpiece having a predetermined electric resistance by energization heating, and hot press molding for press-molding a plate-like workpiece heated by the energization heating method. Regarding the method.

  For example, a plate-like material (plate-like workpiece) such as a steel plate used for a car body such as an automobile is generally used after being formed into a predetermined shape by press molding. In addition, when using a plate-like workpiece such as a high-tensile steel plate in order to reduce the weight or increase the strength of the vehicle body, it is possible to perform hot press molding in which the workpiece is heated and press-molded after improving the formability. Molding is done.

  Thus, when press-molding by heating a plate-shaped workpiece, it is required to heat the plate-shaped workpiece quickly in order to shorten the molding cycle time. In response to such demands, there is known an energization heating method in which electrodes are attached to both ends of a plate-shaped workpiece and the electrodes are energized to quickly heat the workpiece by Joule heat generated in the plate-shaped workpiece.

  However, when electrodes are attached to both ends of a plate-shaped workpiece and heated by energization heating, the plate-shaped workpiece formed in a rectangular shape can be heated substantially uniformly, but is formed in a non-rectangular shape. In a plate-shaped workpiece, since the cross-sectional areas differ in the energization direction between the electrodes, the heating temperature of the workpiece varies, and the workpiece elongation and the strength of the molded product may vary in press molding. Even when the plate-like workpiece is formed in a rectangular shape, the same problem occurs when the thickness of the workpiece differs in the energization direction between the electrodes.

  On the other hand, as an example of suppressing variation in the heating temperature of a non-rectangular plate workpiece, for example, Patent Document 1 discloses that the sides of the plate workpiece facing each other in the longitudinal direction are orthogonal to the direction. A plurality of pairs of electrodes opposed to each other in the direction to be attached and the energization amount is adjusted for each electrode pair is disclosed.

  Further, for example, in Patent Document 2, four or more electrodes are attached to the peripheral portion of a plate-shaped workpiece, two of the electrodes are sequentially selected, and a current is passed between the two electrodes. In addition, there is disclosed a technique in which a plate-like workpiece is heated to have a desired temperature distribution.

  Furthermore, for example, in Patent Document 3, a pair of bar electrodes are arranged in parallel on opposite sides of each part in the longitudinal direction of the plate-like workpiece, and a rectangular shape is formed between the pair of bar electrodes. A device that appropriately controls energization between a pair of electrodes is disclosed.

JP 2002-248525 A JP 2011-189402 A JP 2011-183418 A

  However, when the plate-like workpiece is heated by energization heating as described in Patent Literature 1 to Patent Literature 3, variation in the heating temperature of the plate-like workpiece formed in a non-rectangular shape can be suppressed. Since it is necessary to prepare a very large number of electrodes according to the shape of the workpiece or to perform complicated energization control between the electrodes, the apparatus used for energization heating becomes complicated and the cost increases. Therefore, when heating a plate-shaped workpiece formed in a non-rectangular shape by energization heating, it is desired to relatively easily suppress variations in the heating temperature of the plate-shaped workpiece.

  Therefore, the present invention suppresses variations in the heating temperature of the plate-shaped workpiece relatively easily even when the plate-shaped workpiece formed in a non-rectangular shape is heated when the plate-shaped workpiece is heated by energization heating. The basic purpose is to be able to.

  In order to solve the above problems, the present invention is configured as follows.

First, the invention according to claim 1 of the present application is an energization heating method in which a pair of electrodes spaced apart from each other are attached to a conductive plate-like workpiece having a predetermined electric resistance and energized to heat the plate-like workpiece. Preparing the plurality of plate-like workpieces each formed in a predetermined shape, superposing the plurality of plate-like workpieces, and superposing the plurality of plate-like workpieces, A step of attaching a pair of electrodes to the plate-shaped workpiece; and a step of energizing between the two electrodes; and the step of preparing the plurality of plate-shaped workpieces and the step of superimposing the plurality of plate-shaped workpieces, superimposing the plurality of plate-shaped workpiece is prepared so that the sum of the cross-sectional area in a cross section perpendicular to the flowing direction of a plurality of plate-shaped workpiece is a constant Te the current direction odor It is characterized in that.

  The invention according to claim 2 of the present application is the clamp member disposed on the opposite side of the electrode with the electrode and the plurality of plate-like workpieces sandwiched in the step of attaching the electrode in the invention according to claim 1. And sandwiching the plurality of plate-like workpieces, and attaching the electrodes to the plurality of plate-like workpieces.

  Furthermore, the invention according to claim 3 of the present application is the invention according to claim 1 or 2, wherein the plurality of plate-like workpieces are overlapped with each other between the step of energizing the electrodes. A step of clamping the plurality of plate-like workpieces at least at one or more positions between the electrodes using a clamping means for clamping the plate-like workpiece.

  Furthermore, the invention according to claim 4 of the present application includes a pair of electrodes that are spaced apart from each other, and the pair of electrodes are attached to a plurality of conductive plate-like workpieces having a predetermined electrical resistance to energize the electrodes. An energization means for heating the plurality of plate-like workpieces, and when the plurality of plate-like workpieces are energized between the electrodes, the sum of the cross-sectional areas in a cross section perpendicular to the energization direction of the plurality of plate-like workpieces is An energization heating apparatus that heats the plurality of plate-like workpieces by attaching a pair of electrodes to the plurality of plate-like workpieces and energizing the electrodes so as to be substantially constant in the energization direction, , Extending in a direction substantially perpendicular to the energization direction, and provided so as to be in contact with the entire direction perpendicular to the energization direction of the plurality of stacked plate-like workpieces.

  Still further, the invention according to claim 5 of the present application is the invention according to claim 4, wherein the plurality of plate-like workpieces are engaged with at least a part of the peripheral portions of the plurality of plate-like workpieces superimposed. A positioning member for positioning at a predetermined position is provided.

  Furthermore, the invention according to claim 6 of the present application is a hot press forming method, in which the plate-like workpiece is heated by the energization heating method according to any one of claims 1 to 3 and formed. The heated plate-like workpiece is press-molded using a mold.

  With the above configuration, according to the invention of each claim of the present application, the following effects can be obtained.

First, according to the invention according to claim 1 of the present application, a plurality of plate-shaped workpiece as the sum of the cross sectional area is a constant Te energizing direction odor in a cross section perpendicular to the flowing direction of a plurality of plate-shaped workpiece is prepared By superimposing, Joule heat generated from a plurality of plate-like workpieces when energizing between both electrodes can be made substantially equal in the energization direction, so variation in the heating temperature of the plate-like workpieces can be suppressed relatively easily. can do. Even in the case of heating the formed plate workpiece in a non-rectangular shape, a plurality of plate-shaped workpiece as the sum of the cross-sectional area in a cross section perpendicular to the flowing direction of a plurality of plate-shaped workpiece is a constant Te energizing direction odor By preparing and overlaying, variations in the heating temperature of the plate-like workpiece formed in a non-rectangular shape can be suppressed.

  According to the invention of claim 2 of the present application, the plurality of plate-like workpieces are sandwiched by the electrode and the clamp member disposed on the opposite side of the electrode with the plurality of plate-like workpieces interposed therebetween. By attaching the electrode to the electrode, it is possible to reliably attach the electrode to the plate-like workpiece by a relatively simple method, and the above effect can be effectively achieved.

  Furthermore, according to the invention according to claim 3 of the present application, a plurality of plate-shaped workpieces stacked between the electrodes are clamped by clamping a plurality of plate-shaped workpieces at least at one or more positions between the electrodes using the clamping means. It is possible to prevent a gap from being generated between the workpieces, and the effect can be more effectively achieved.

  Furthermore, according to the invention according to claim 4 of the present application, when a plurality of plate-like workpieces are energized between both electrodes, the sum of the cross-sectional areas in a cross section perpendicular to the energization direction of the plurality of plate-like workpieces When a plurality of plates are energized by heating a plurality of plate-shaped workpieces by attaching a pair of electrodes to the plurality of plate-shaped workpieces in a state of being superposed so as to be substantially constant, Since the Joule heat generated from the plate-like workpiece can be made substantially equal in the energizing direction, variations in the heating temperature of the plate-like workpiece can be suppressed relatively easily. Even when heating a non-rectangular plate-shaped workpiece, the plurality of plate-shaped workpieces are arranged so that the sum of the cross-sectional areas in the cross-section perpendicular to the energizing direction of the plurality of plate-shaped workpieces is substantially constant in the energizing direction. By overlapping, it is possible to suppress variations in the heating temperature of the plate-like workpiece formed in a non-rectangular shape.

  Further, the electrode extends in a direction substantially orthogonal to the energization direction, and is provided so as to contact the entire direction orthogonal to the energization direction of the plurality of stacked plate-like workpieces. Since the contact area of the electrode can be increased as compared with the case where it is in contact with a part of the direction orthogonal to the energization direction of the workpiece, the current flows substantially uniformly in each energization direction of the plurality of plate-like workpieces. At the same time, the Joule heat generated at the contact portion between the electrode and the plate-like workpiece can be reduced, and the above-described effect can be achieved more advantageously.

  Furthermore, according to the invention according to claim 5 of the present application, the positioning member that engages with at least a part of the peripheral portions of the plurality of stacked plate-like workpieces to position the plurality of plate-like workpieces at a predetermined position. By providing, it can prevent that the position of a plate-shaped workpiece shifts, can hold a plate-shaped workpiece accurately in a predetermined position, and can show the above-mentioned effect effectively.

  Furthermore, according to the invention according to claim 6 of the present application, the plurality of plate-like members stacked so that the sum of the cross-sectional areas in the cross-section orthogonal to the energizing direction of the plurality of plate-like workpieces is substantially constant in the energizing direction. By energizing and heating the workpiece and press-molding the heated plate-like workpiece using a mold, the plate-like workpiece can be rapidly heated while suppressing variations in the heating temperature of the plate-like workpiece. It is possible to prevent variations in the material properties of the sheet-like workpiece and to shorten the press molding cycle time of the plate-like workpiece.

It is a schematic plan view of the electric heating apparatus which concerns on 1st Embodiment of this invention. It is the side view of the said heating apparatus seen from the Y2A direction, Y2B direction, and Y2C direction in FIG. It is explanatory drawing for demonstrating the plate-shaped workpiece | work heated in the said electrical heating apparatus. It is explanatory drawing for demonstrating the cross-sectional area of the plate-shaped workpiece | work heated in the said electricity heating apparatus. It is explanatory drawing for demonstrating the temperature measurement conditions of the plate-shaped workpiece | work heated by the electrical heating used as Example 1. FIG. It is explanatory drawing for demonstrating the temperature measurement conditions of the plate-shaped workpiece | work heated by the electrical heating used as a comparative example. It is the schematic which shows an example of the press molding apparatus provided with the said electricity heating apparatus. It is the schematic of the electricity heating apparatus which concerns on 2nd Embodiment of this invention. It is explanatory drawing for demonstrating the temperature measurement conditions of the plate-shaped workpiece | work heated by the energization heating used as Example 2. FIG. It is the schematic of the electricity heating apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the 1st, 2nd and 3rd modification of the plate-shaped workpiece | work heated in the electric heating apparatus which concerns on embodiment of this invention. It is a figure which shows the 4th modification of the plate-shaped workpiece | work heated in the electric heating apparatus which concerns on embodiment of this invention. It is a figure which shows the 5th modification of the plate-shaped workpiece | work heated in the electric heating apparatus which concerns on embodiment of this invention. It is a figure which shows the 6th modification of the plate-shaped workpiece | work heated in the electric heating apparatus which concerns on embodiment of this invention. It is a figure which shows the 7th modification of the plate-shaped workpiece | work heated in the electric heating apparatus which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic plan view of an electric heating device according to the first embodiment of the present invention. FIG. 2 is a side view of the energization heating device viewed from the Y2A direction, the Y2B direction, and the Y2C direction in FIG. 1, and FIGS. 2 (a), 2 (b), and 2 (c) are respectively. It is the side view of the said electricity heating apparatus seen from Y2A direction, Y2B direction, and Y2C direction. 2A, 2B, and 2C, a part of a positioning member to be described later is indicated by a two-dot chain line, and this is shown in a transparent state.

  The energization heating device 1 attaches electrodes separated from each other to a plurality of plate-like workpieces (blanks) formed in a substantially flat plate shape, and energizes the plate-like workpieces by Joule heat generated in the plurality of plate-like workpieces. In this embodiment, although it is not limited to this, it has shown about heating the two plate-shaped workpieces piled up.

  As shown in FIGS. 1 and 2, the energization heating device 1 includes an energization means 10 for electrically heating two conductive plate-like workpieces W1 and W2 having a predetermined electric resistance. The energization means 10 includes a pair of electrodes 11 that are spaced apart from each other in parallel, a power source 12 that supplies DC or AC power to the electrode 11, and a cable 13 that connects the power source 12 and the electrode 11. The plate-like workpieces W1 and W2 are heated by bringing the pair of electrodes 11 into contact with both ends of the superimposed plate-like workpieces W1 and W2 and energizing them. The pair of electrodes 11 are bar electrodes formed in a substantially rectangular parallelepiped shape using a material such as copper, for example, and one electrode 11a is used as a positive electrode and the other electrode 11b is used as a negative electrode.

  As shown in FIG. 2, the electric heating device 1 also includes clamp members 15 that are respectively disposed above the pair of electrodes 11. The clamp member 15 includes a substantially rectangular parallelepiped clamp base portion 16 extending substantially parallel to the extending direction of the electrode 11, a pin portion 17 having a tip portion contacting the plate-like workpieces W <b> 1 and W <b> 2, a clamp base portion 15 and a pin portion 17. The clamp base 16 is connected to a clamp base moving means (not shown) and is movable up and down as indicated by an arrow Z1.

  The clamp member 15 is disposed on the opposite side of the electrode 11 with the plate-like workpieces W1 and W2 interposed therebetween, and is moved downward when the clamp base 16 is moved downward by the clamp base moving means. When attaching the electrode 11 to the plate-like workpieces W1 and W2, the clamp member 15 is moved downward, and the plate-like workpieces W1 and W2 can be sandwiched and attached by the electrode 11 and the clamp member 15. Thereby, the electrode 11 can be reliably attached to the plate-like workpieces W1 and W2 by a relatively simple method.

  The energization heating device 1 includes positioning members 21 and 22 for holding the plate-like workpieces W1 and W2 at predetermined positions. The positioning member 21 is formed in a substantially rectangular parallelepiped shape, and is disposed outside the pair of electrodes 11. As shown in FIG. 2A, the pair of electrodes 11 has a side on which the other electrode 11 is disposed. The other surface is coupled to extend upward from the electrode 11.

  Thereby, the positioning member 21 engages the positioning member 21 with a part of the peripheral edge of the plate-like workpieces W1 and W2, specifically, the parallel opposite sides W1a and W2a of the plate-like workpieces W1 and W2. The plate-like workpieces W1, W2 can be held at predetermined positions in a direction substantially orthogonal to the extending direction of the electrode 11.

  On the other hand, the positioning member 22 is formed in a substantially rectangular parallelepiped shape and is disposed inside the pair of electrodes 11. As shown in FIG. 1, the positioning member 22 extends in a direction substantially orthogonal to the direction in which the electrodes 11 extend between the opposing ends of the pair of electrodes 11, and as indicated by a two-dot chain line in FIG. , Extending upward from the electrode 11.

  As a result, the positioning member 22 includes a part of the peripheral portion of the plate-like workpieces W1 and W2, specifically, the sides W1b and W2b perpendicular to the parallel opposite sides W1a and W2a of the plate-like workpieces W1 and W2. The plate-like workpieces W1, W2 can be held at predetermined positions in the extending direction of the electrode 11.

  The electric heating device 1 is also provided with a control unit (not shown) that comprehensively controls the configuration related to the electric heating device 1, and the control unit includes an electric current supplying means 10, the clamp base moving means, and the like. The operation can be controlled. The control unit is preferably configured with a microcomputer as a main part.

  In the electric heating apparatus 1 configured as described above, two plate-like workpieces W1 and W2 each having a predetermined shape are prepared in a state where the clamp member 15 is moved upward, and the positioning members 21 and 22 are prepared. The two plate-like workpieces W1 and W2 are superposed on the electrode 11 while being positioned at a predetermined position by moving the clamp member 15 downward with respect to the two plate-like workpieces W1 and W2 superposed on each other. The pair of electrodes 11 are attached to the plate-like workpieces W1 and W2 by sandwiching the plate-like workpieces W1 and W2 between the electrodes 11 and the clamp member 15, and thereafter, the two electrodes 11 are energized to form two The plate-like workpieces W1 and W2 are heated.

Here, the plate-like workpieces W1 and W2 to be heated in the energization heating apparatus 1 according to the present embodiment will be described.
FIG. 3 is an explanatory diagram for explaining a plate-like workpiece heated in the energization heating apparatus, and FIG. 3 (a) shows the plate-like workpiece before being formed into a predetermined shape, and FIG. ) Shows the plate-like workpiece after being formed into a predetermined shape.

  In the energization heating apparatus 1, conductive plate-like workpieces W1 and W2 having a predetermined electric resistance such as high-tensile steel plates are heated by energization heating, and the plate-like workpieces W1 and W2 to be heated are shown in FIG. As shown in a), it is formed by cutting a rectangular plate-shaped workpiece having a predetermined thickness by a point-symmetric linear line L1 (shown by a two-dot chain line) passing through a diagonal intersection C1. . In FIG. 3B, the first plate-like workpiece W1 is shown upside down. As shown in this figure, the first and second plate-like workpieces W1, W2 have the same electrical resistance. It has the same shape with a ratio, and a pair of opposite sides are formed in a right trapezoid shape parallel to each other.

  FIG. 4 is an explanatory diagram for explaining a cross-sectional area of a plate-like workpiece heated in the energization heating apparatus, and FIG. 4 (a) shows a state in which two plate-like workpieces are superimposed on an electrode. FIG. 4B shows the relationship between the distance from the positive electrode in the energization direction between the electrodes and the cross-sectional area of the plate-like workpiece. In FIG. 4B, the cross-sectional areas of the first and second plate-like workpieces W1 and W2 in the cross section perpendicular to the energizing direction are indicated by lines L2 and L3, respectively, and the first and second plate-like workpieces are shown. The sum of the cross-sectional areas in the cross section perpendicular to the energizing direction of W1 and W2 is indicated by a line L4.

  In the electric heating apparatus 1, the first and second plate-like workpieces W <b> 1 and W <b> 2 are superimposed on the electrode 11 and arranged at a predetermined position. The first plate-like workpiece W1 and the second plate-like workpiece W2 are overlapped so that the right-angle portions thereof coincide with each other, and the electrodes 11 are attached to both end portions of the plate-like workpieces W1 and W2, respectively. Placed in.

  As shown in FIG. 4A, at a distance x1 from the positive electrode 11a in the energization direction between the electrodes 11, the widths perpendicular to the energization direction of the plate-like workpieces W1, W2 are y1, y2, and the plate-like workpieces W1, When the thickness of W2 is t, the cross-sectional areas S1 and S2 in the cross section orthogonal to the energizing direction of the plate-like workpieces W1 and W2 are the widths y1 and y2 of the plate-like workpieces W1 and W2 and the plate-like workpieces W1 and W2, respectively. Represented by products (y1 · t) and (y2 · t) with thickness t, the sum of the cross-sectional areas (S1 + S2) in the cross section perpendicular to the energizing direction of the first and second plate-like workpieces W1 and W2 is: It is expressed by (y1 · t + y2 · t).

  As shown in FIG. 4B, the cross-sectional area of the first plate-like workpiece W1 in the cross section perpendicular to the energizing direction of the plate-like workpiece W1 increases as the distance from the positive electrode 11a in the energizing direction increases. On the other hand, as the distance from the positive electrode 11a in the energization direction of the second plate-like workpiece W2 increases, the cross-sectional area in the cross section orthogonal to the energization direction of the plate-like workpiece W2 decreases (see the line L3). However, in the present embodiment, the sum of the cross-sectional areas in the cross sections orthogonal to the energizing direction of the first and second plate-like workpieces W1 and W2 that are overlapped is substantially the same regardless of the distance from the positive electrode 11a in the energizing direction. First and second plate-like workpieces W1 and W2 are prepared and overlapped so as to be constant (see line L4).

  In this embodiment, the first and second plate-like workpieces W1 and W2 have a substantially constant cross-sectional area in the energization direction in a cross section perpendicular to the energization direction of the first and second plate-like workpieces W1 and W2. The three or more plate-like workpieces are overlapped so that the sum of the cross-sectional areas in the cross section orthogonal to the energizing direction of the three or more plate-like workpieces is substantially constant in the energizing direction. Also good.

  As described above, in the present embodiment, the energization heating for heating the plate-like workpieces W1 and W2 by attaching and energizing the pair of electrodes 11 separated from each other to the conductive plate-like workpieces W1 and W2 having a predetermined electric resistance. , A plurality of plate-like workpieces W1, W2 each having a predetermined shape are prepared, a plurality of plate-like workpieces W1, W2 are overlaid, and a plurality of plate-like workpieces W1, W2 are overlaid. A pair of electrodes 11 is attached to the plate-like workpieces W1 and W2, and the electrodes 11 are energized. In that case, the plurality of plate-like workpieces W1 and W2 are prepared and overlapped so that the sum of the cross-sectional areas in the cross section perpendicular to the energization direction of the plurality of plate-like workpieces W1 and W2 is substantially constant in the energization direction.

  As a result, when energizing between both electrodes 11, Joule heat generated from the plurality of plate-like workpieces W1, W2 with the resistance values of the plurality of plate-like workpieces W1, W2 superposed in the energization direction being made substantially constant. Since it can be made substantially equal in the energization direction, variations in the heating temperature of the plate-like workpieces W1, W2 can be suppressed relatively easily. Even when the plate-like workpieces W1 and W2 formed in a non-rectangular shape such as a right trapezoid shape are heated, the sum of the cross-sectional areas in the cross section perpendicular to the energization direction of the plurality of plate-like workpieces W1 and W2 is substantially in the energization direction. By preparing and stacking a plurality of plate-like workpieces W1, W2 so as to be constant, variations in the heating temperature of the plate-like workpieces W1, W2 formed in a non-rectangular shape can be suppressed.

  Further, a positioning member 21 that engages with at least a part W1a, W1b, W2a, W2b of the peripheral portions of the plurality of stacked plate-like workpieces W1, W2 to position the plurality of plate-like workpieces W1, W2 at predetermined positions. , 22 can prevent the positions of the plate-like workpieces W1, W2 from being shifted and can hold the plate-like workpieces W1, W2 at a predetermined position with high accuracy, and the above-described effects can be effectively achieved. it can.

  In the electric heating device 1, the positioning member 21 is coupled to each of the pair of electrodes 11, and the electrode 11 and the positioning member 21 are formed separately. However, the positioning member is formed of an electrode, and the electrode is positioned. You may make it form a member integrally.

  In the present embodiment, the first and second plate-like workpieces W1 and W2 formed in a right trapezoid shape are overlapped so that the sum of the cross-sectional areas in the cross section orthogonal to the energizing direction is substantially constant in the energizing direction. The first and second plate-like workpieces W1, W2 were heated by energization heating by energization, and the heating temperature of the first and second plate-like workpieces W1, W2 was measured.

  FIG. 5 is an explanatory diagram for explaining temperature measurement conditions of a plate-like workpiece heated by energization heating used as Example 1. In FIG. 5, two plate-like workpieces and electrodes used as Example 1 are used. Only shows. 5A is a plan view showing the arrangement of the plate-like workpiece and the electrodes, and FIGS. 5B, 5C, and 5D are respectively the Y5B direction and Y5C in FIG. 5A. The side view of the said plate-shaped workpiece | work and electrode seen from the direction and Y5D direction is shown.

  As the conductive first and second plate-like workpieces W1 and W2 having a predetermined electrical resistivity, a cold-rolled high-strength steel plate SPFC440 having a thickness of 1.6 mm is used, as shown in FIG. A plate-shaped workpiece formed in a rectangular shape having a width of 280 mm and a width of 110 mm is cut by a point-symmetrical straight line L1 passing through the diagonal intersection C1 to form a right trapezoidal shape having the same shape. Prepared. Specifically, as shown in FIG. 5A, the first and second plate-like workpieces W1 and W2 are formed in a right trapezoidal shape having an upper side of 22 mm, a lower side of 88 mm, and a length of 280 mm. Was used.

  As shown in FIG. 5, the first and second plate-like workpieces W1 and W2 are superposed on the first and second plate-like workpieces W1 and W2 as shown in FIG. The first and second plate-like workpieces W1 and W2 are sandwiched between the electrode 11 and the clamp member 15 in a state where the workpieces W1 and W2 are overlapped, and the electrodes are placed on the first and second plate-like workpieces W1 and W2. 11 was attached, both electrodes 11 were energized, and the first and second plate-like workpieces W1 and W2 were heated by energization heating. The energization was carried out for 10 seconds using a direct current power source and setting the current value to 4.2 A.

  And immediately after heating the 1st and 2nd plate-like workpieces W1 and W2 by energization heating for 10 seconds, temperature measurement is performed at each measurement position of the 1st and 2nd plate-like workpieces W1 and W2 using a thermocouple. went. Specifically, as shown in FIGS. 5A and 5B, the first plate-like workpiece W1 is measured at each position indicated by P1 to P4 on the upper surface of the first plate-like workpiece W1. And about the 2nd plate-shaped workpiece W2, it measured in each position shown by P5-P8 in the lower surface of the 2nd plate-shaped workpiece W2. In FIG. 5A, the measurement positions P5 to P8 of the second plate-like workpiece W2 are shown in parentheses.

  As a comparative example, in the energization heating apparatus 1, the first plate-like workpiece W1 is heated by arranging only the first plate-like workpiece W1 on the electrode 11 and energizing the first plate-like workpiece. The heating temperature of W1 was measured. Except that the second plate-like workpiece W2 is not overlapped between the electrode 11 and the first plate-like workpiece W1, energization heating is performed in the same manner as in Example 1 to obtain the first plate-like workpiece W1. The heating temperature was measured.

  FIG. 6 is an explanatory diagram for explaining temperature measurement conditions of a plate-like workpiece heated by energization heating used as a comparative example, and FIG. 6 shows only the plate-like workpiece and electrodes used as a comparative example. Yes. 6A is a plan view showing the arrangement of the plate-like workpiece and the electrodes, and FIGS. 6B, 6C, and 6D are respectively the Y6B direction and Y6C in FIG. 6A. The side view of the said plate-shaped workpiece and electrode seen from the direction and Y6D direction is shown.

  The first plate-like workpiece W1 used as the comparative example was the same as the first plate-like workpiece W1 used in Example 1, and was arranged on the electrode 11 at the same position as in Example 1. Also in the comparative example, the first plate-like workpiece W1 is sandwiched between the electrode 11 and the clamp member 15, the electrode 11 is attached to the first plate-like workpiece W1, and the current between both the electrodes 11 is energized. The workpiece W1 was heated by energization heating. The current heating conditions and the measurement position of the first plate-like workpiece were the same as in Example 1.

  The temperature measurement results of the first and second plate-like workpieces W1 and W2 heated in Example 1 are shown in Table 1 below, and the temperature measurement result of the first plate-like workpiece W1 heated in Comparative Example 1 is shown. It is shown in Table 2 below. In Table 1, the measurement temperature at each measurement position of the first and second plate-like workpieces W1 and W2, the highest measurement temperature of the first and second plate-like workpieces W1 and W2, and the temperature at each measurement position. Table 2 shows the measurement temperature at each measurement position of the first plate-like workpiece W1, the highest measurement temperature of the first plate-like workpiece W1, and the temperature difference at each measurement position.

  As shown in Table 1, in Example 1, for the first and second plate-like workpieces W1 and W2, the maximum temperature 441 ° C. was measured at the measurement position P8 of the second plate-like workpiece W2, and the first plate The lowest temperature of 227 ° C. was measured at the measurement position P1 of the workpiece W1, and the difference between these temperatures was 214 ° C.

  Further, for Example 1, only the first plate-like workpiece W1 has the maximum temperature 325 ° C. measured at the measurement position P3, the minimum temperature 227 ° C. measured at the measurement position P1, and the temperature difference between these is 98 ° C. As a result, only with the second plate-like workpiece W2, the maximum temperature 441 ° C. is measured at the measurement position P8, the minimum temperature 268 ° C. is measured at the measurement position P6, and the temperature difference is 173 ° C. Results were obtained.

  On the other hand, as shown in Table 2, in Comparative Example 1, the maximum temperature of 577 ° C. was measured at the measurement position P4 and the minimum temperature of 144 ° C. was measured at the measurement position P2, and these temperatures were measured. The result was a difference of 433 ° C.

  From these results, in the comparative example, the temperature difference between the heated plate-like workpieces W1 is 433 ° C., whereas in Example 1, the temperature difference between the heated first and second plate-like workpieces W1 and W2 is different. The plate-like workpieces W1 and W2 are prepared and overlapped so that the sum of the cross-sectional areas in the cross section perpendicular to the energization direction of the plate-like workpieces W1 and W2 is 214 ° C. It can be seen that variations in the heating temperature of the plate-like workpiece can be suppressed.

  In particular, in the comparative example, the temperature difference of the first plate-like workpiece W1 is 433 ° C. in one comparative example, whereas in Example 1, the temperature difference of the first plate-like workpiece W1 is 98 ° C. It can be seen that the temperature difference of the second plate-like workpiece W2 is 173 ° C., and the variation in the heating temperature of one plate-like workpiece can be greatly suppressed.

  In this way, the plurality of plate-like workpieces W1 and W2 are prepared and overlapped so that the sum of the cross-sectional areas in the cross section orthogonal to the energization direction between the electrodes 11 is substantially constant in the energization direction. When heating the plate-shaped workpiece formed on the plate by electric heating, variation in the heating temperature of the plate-shaped workpiece can be suppressed.

  Thus, after heating the plate-like workpieces W1 and W2 using the energization heating device 1, the heated plate-like workpieces W1 and W2 are formed using a conveying means such as a conveyance robot or a conveyance belt. The plate-like workpieces W1 and W2 can be hot press-molded by being conveyed to a press-molding apparatus equipped with the above-mentioned, and the current heating apparatus 1 is incorporated into the press molding apparatus and heated by current heating. The formed plate-like workpiece may be press-molded.

  FIG. 7 is a schematic diagram illustrating an example of a press forming apparatus including the energization heating apparatus. The press molding apparatus 31 provided with the electric heating apparatus 1 shown in FIG. 7 includes a punch 40 having a projecting portion 41 projecting downward, and a recess 51 formed in a concave shape corresponding to the projecting portion 41. A molding die 30 having a die 50 is provided, and a plate-like workpiece can be formed in a predetermined shape by combining the protruding portion 41 and the recessed portion 51.

  The punch 40 is attached to a punch plate 44 via a spring 42 and a spring guide 43, and the punch plate 44 is attached to a punch holder 45. The punch holder 45 is connected to a punch moving mechanism (not shown), and the punch 40 is moved in the vertical direction by the punch moving mechanism, so that the punch 40 can be moved in the vertical direction. On the other hand, the die 50 is fixed to the die holder 52.

  The press molding apparatus 31 is also provided with the energization heating apparatus 1 having the above-described energization means 10, and the die 50 is provided with a pair of electrodes 11 on both sides of the recess 51 with the recess 51 of the die 50 interposed therebetween. . The pair of electrodes 11 is provided so as to protrude from the upper surface of the die 50, and is connected to the power source 12 by the cable 13. A clamp member 15 is attached above each of the pair of electrodes 11.

  In the press molding apparatus 31, the sum of the cross-sectional areas in the cross section perpendicular to the energization direction of the first and second plate-like workpieces W1 and W2 is substantially constant in the energization direction with the punch 40 moved upward. The first and second plate-like workpieces W1 and W2 prepared and superimposed on each other are sandwiched between the electrode 11 and the clamp member 15, and the pair of electrodes 11 are attached to the first and second plate-like workpieces W1 and W2. After that, the first and second plate-like workpieces W1, W2 are heated by energization heating by energizing between the electrodes 11.

  Then, after the first and second plate-like workpieces W1 and W2 are heated, the clamp member 15 is moved upward, and the first plate-like workpiece W1 is moved from the press molding apparatus 31 by using a conveying means (not shown). Then, the punch 40 is moved downward, the heated second plate-like workpiece W2 is press-molded by using the molding die 30, and the second plate-like workpiece W2 is hot press-molded.

  As described above, the first and second plate-like workpieces W1 and W2 are heated by the energization heating apparatus 1 using the press molding apparatus 31 incorporating the energization heating apparatus 1, and then the molding die 30 is used. The second plate-like workpiece W2 heated in this way may be press-molded and hot press-molded. The hot press forming is not limited to press-molding a plate-shaped workpiece by heating to a temperature higher than the quenching temperature, and includes hot-press molding that is performed by heating the plate-shaped workpiece to a temperature lower than the quenching temperature.

  In this way, the plurality of plate-like workpieces W1, W2 that are overlapped so that the sum of the cross-sectional areas in the cross section perpendicular to the energization direction of the plurality of plate-like workpieces W1, W2 is substantially constant in the energization direction is energized and heated. By pressing the heated plate-like workpieces W1 and W2 using a molding die, the plate-like workpiece can be rapidly heated while suppressing variations in the heating temperature of the plate-like workpiece. It is possible to prevent variations in the material properties of the sheet material and to reduce the press molding cycle time of the plate-like workpiece.

FIG. 8 is a schematic view of an electric heating device according to a second embodiment of the present invention, and FIG. 8 (a) is a schematic plan view of the electric heating device, FIG. 8 (b), FIG. 8 (c) and FIG. FIG. 8D is a side view of the energization heating device viewed from the Y8B direction, Y8C direction, and Y8D direction in FIG. In FIGS. 8B, 8C, and 8D, a part of the positioning members 21 and 22 is indicated by a two-dot chain line, and this is shown in a transparent state.
The electric heating apparatus 61 according to the second embodiment of the present invention is the same as the electric heating apparatus 1 according to the first embodiment of the present invention except that the shape of the electrode 11 is different. The same components as those in FIG.

  As shown in FIG. 8, the energization heating device 61 according to the second embodiment of the present invention also has a pair of electrodes 71 that are separated from each other, and the pair of electrodes 71 are attached to the plate-like workpieces W <b> 1 and W <b> 2 to energize. Thus, the energizing means 70 for heating the plate-like workpieces W1 and W2 is provided, and prepared and superimposed so that the sum of the cross-sectional areas in the cross section perpendicular to the energizing direction of the plate-like workpieces W1 and W2 is substantially constant in the energizing direction. Although the plate-like workpieces W1 and W2 are heated, in the energization heating device 61, the electrode 71 extends in a direction substantially orthogonal to the energization direction, but the energization of the stacked plate-like workpieces W1 and W2 is performed. It is provided so as to contact the entire direction orthogonal to the direction.

  The positive electrode 71a of the electrode 71 is formed in the same manner as the positive electrode 11a of the energization heating device 1, and as shown in FIG. 8C, the entire direction orthogonal to the energizing direction of the stacked plate-like workpieces W1 and W2. However, the negative electrode 71b of the electrode 71 is formed in a substantially rectangular parallelepiped shape like the negative electrode 11b of the energization heating device 1 as shown in FIG. 8 (d). And a projecting portion 71d projecting from the main body portion 71c, and the main body portion 71c and the projecting portion 71d are integrally formed.

  The protruding portion 71d of the negative electrode 71b has the same length as the main body portion 71c in the energization direction and the same thickness as the second plate-like workpiece W2, and the main body portion 71c and the first plate-like workpiece W1. It is formed to fill the space formed between the two. Thereby, also about the negative electrode 71b, it is provided so that the whole direction orthogonal to the electricity supply direction of the piled plate-shaped workpieces W1 and W2 may be contacted.

  Also in the energization heating device 61 configured in this way, the plurality of plate-like workpieces W1 so that the sum of the cross-sectional areas in the cross section orthogonal to the energization direction of the plurality of plate-like works W1, W2 is substantially constant in the energization direction. , W2 are prepared and overlapped so that the Joule heat generated from the plurality of plate-like workpieces W1, W2 when energizing between the electrodes 71 can be made substantially equal in the energizing direction, so that the plate-like shape is relatively easy. Variation in the heating temperature of the workpiece can be suppressed.

  In the present embodiment, the sum of the cross-sectional areas of the first and second plate-like workpieces W1, W2 formed in a right-angled trapezoidal shape in the cross section orthogonal to the energization direction is substantially the same in the energization direction. The first and second plate-like workpieces W1 and W2 were heated by energization heating by superposing them so as to be constant, and the heating temperatures of the first and second plate-like workpieces W1 and W2 were measured.

  FIG. 9 is an explanatory diagram for explaining temperature measurement conditions of a plate-like workpiece heated by energization heating used as Example 2. In FIG. 9, two plate-like workpieces and electrodes used as Example 2 are used. Only shows. 9A is a plan view showing the arrangement of the plate-like workpiece and the electrodes, and FIGS. 9B, 9C, and 9D are respectively the Y9B direction and Y9C in FIG. 9A. The side view of the said plate-shaped workpiece | work and electrode seen from the direction and Y9D direction is shown.

  As shown in FIG. 9, also in the second embodiment using the energization heating device 61, the same plate-like workpieces W <b> 1 and W <b> 2 as in the first embodiment are used and orthogonal to the energizing direction of the plate-like workpieces W <b> 1 and W <b> 2 on the electrode 71. The first and second plate-like workpieces W1 and W2 are heated by energization heating so that the sum of the cross-sectional areas in the cross-sections is substantially constant in the energization direction, and the electrodes 11 are energized. The heating temperature of the second plate-like workpieces W1 and W2 was measured. The electrical heating conditions and temperature measurement positions were also the same as in Example 1.

  Table 3 below shows the temperature measurement results of the first and second plate-like workpieces W1 and W2 heated in the second embodiment. In Table 3, the measurement temperature at each measurement position of the first and second plate-like workpieces W1 and W2, the highest measurement temperature of the first and second plate-like workpieces W1 and W2, and the temperature at each measurement position. Shows the difference.

  As shown in Table 3, in Example 2, for the first and second plate-like workpieces W1 and W2, the maximum temperature 431 ° C. was measured at the measurement position P8 of the second plate-like workpiece W2, and the first plate The minimum temperature of 309 ° C. was measured at the measurement position P1 of the workpiece W1, and a measurement result that the temperature difference between them was 122 ° C. was obtained.

  In Example 2, only the first plate-like workpiece W1 has the maximum temperature 372 ° C. measured at the measurement position P4, the minimum temperature 309 ° C. measured at the measurement position P1, and the temperature difference between these is 63 ° C. As a result, only with the second plate-like workpiece W2, the maximum temperature 431 ° C. is measured at the measurement position P8, the minimum temperature 330 ° C. is measured at the measurement position P6, and the temperature difference is 101 ° C. Results were obtained.

  As described above, in the comparative example, the temperature difference between the heated plate-like workpieces W1 is 433 ° C., whereas in Example 2, the temperature difference between the heated first and second plate-like workpieces W1 and W2 is different. The plate-like workpieces W1 and W2 are prepared and overlapped so that the sum of the cross-sectional areas in the cross section perpendicular to the energization direction of the plate-like workpieces W1 and W2 is 122 ° C. It can be seen that variations in the heating temperature of the plate-like workpiece can be suppressed.

  In particular, for one plate-like workpiece, the temperature difference of the first plate-like workpiece W1 is 433 ° C. in the comparative example, whereas in Example 2, the temperature difference of the first plate-like workpiece W1 is 63 ° C. It can be seen that the temperature difference of the second plate-like workpiece W2 is 101 ° C., and the variation in the heating temperature of one plate-like workpiece can be greatly suppressed.

  In the second embodiment, the variation in the heating temperature of the plate-like workpieces W1 and W2 can be further suppressed as compared to the first embodiment, and each of the first and second plate-like workpieces W1 and W2 can be suppressed. It can also be seen that variations in the heating temperature of one plate-like workpiece can be further suppressed.

  As described above, even when the current heating device 61 according to the present embodiment is used, the plurality of plate-like workpieces W1 and W2 are overlapped so that the sum of the cross-sectional areas in the cross section perpendicular to the current supply direction is substantially constant in the current supply direction. The Joule heat generated from the plate-like workpieces W1 and W2 when energized between the electrodes 71 is heated by attaching a pair of electrodes 71 to the plurality of plate-like workpieces W1 and W2 and energizing them. Since it can be made substantially equal in the energization direction, variations in the heating temperature of the plate-like workpiece can be suppressed relatively easily. Even when a plate-like workpiece formed in a non-rectangular shape is heated, variation in the heating temperature of the plate-like workpiece formed in a non-rectangular shape can be suppressed.

  In addition, the electrode 71 extends in a direction substantially orthogonal to the energization direction, and is provided so as to be in contact with the entire direction orthogonal to the energization direction of the plurality of stacked plate-like workpieces W1, W2. Since the contact area of the electrode 71 can be increased compared with the case where the electrode 71 is in contact with a part of the direction orthogonal to the energizing direction of the plurality of plate-like workpieces W1, W2, the plurality of plate-like workpieces W1, W2 As the current flows substantially uniformly in the respective energization directions, Joule heat generated at the contact portion between the electrode 71 and the plate-like workpieces W1 and W2 can be reduced, and the above-described effect can be achieved more advantageously. Can do.

FIG. 10 is a schematic view of an electric heating device according to a third embodiment of the present invention, FIG. 10 (a) is a schematic plan view of the electric heating device, and FIG. 10 (b) is FIG. 10 (a). It is a side view of the said electric heating apparatus seen from Y10B direction in FIG. In addition, in FIG.10 (b), the positioning member 22 is shown with the dashed-two dotted line, and this is shown in the permeation | transmission state.
The electric heating device 81 according to the third embodiment of the present invention is further provided with clamping means for clamping the plate-like workpieces W1, W2 between the electrodes 11 in the electric heating device 1 according to the first embodiment. The same components as those of the electric heating device 1 are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIGS. 10 (a) and 10 (b), the energization heating device 81 according to the third embodiment of the present invention also has a pair of electrodes 11 that are separated from each other, and the plate-like workpieces W1, W2 An energizing means 10 for heating the plate-like workpieces W1, W2 by attaching and energizing the pair of electrodes 11 is provided, and the sum of the cross-sectional areas in the cross section orthogonal to the energizing direction of the plate-like workpieces W1, W2 is substantially constant in the energizing direction. The plate-like workpieces W1 and W2 prepared and overlaid so as to become are heated.

  The energization heating device 81 is also provided with clamping means 85 for clamping the plate-like workpieces W1 and W2 at a substantially central portion between the electrodes 11, and the clamping means 85 is an upper clamp for clamping the plate-like workpieces W1 and W2 from above. It is comprised by the member 91 and the lower side clamp member 95 which clamps plate-shaped work W1, W2 from the downward direction.

  The upper clamp 91 is configured in the same manner as the clamp member 15, and has a substantially rectangular parallelepiped clamp base 92 extending substantially parallel to the extending direction of the electrode 11, and a pin portion 93 having a tip portion that contacts the plate-like workpieces W 1, W 2. And a spring 94 coupled to the clamp base 92 and the pin 93, and the clamp base 92 is connected to an upper clamp moving means (not shown) so as to be movable in the vertical direction as indicated by an arrow Z2. Yes.

  On the other hand, the lower clamp 95 is obtained by vertically inverting the upper clamp 91, and has a substantially rectangular parallelepiped clamp base 96 extending substantially parallel to the extending direction of the electrode 11 and a tip portion contacting the plate-like workpieces W1 and W2. A pin portion 97 provided, and a spring 98 coupled to the clamp base portion 96 and the pin portion 97. The clamp base portion 96 is connected to a lower clamp moving means (not shown) and is vertically moved as shown by an arrow Z3. It is configured to be movable.

  In the clamp means 85, the clamp base 91 is moved downward by the upper clamp moving means to move the upper clamp member 91 downward, and the clamp base 96 is moved upward by the lower clamp moving means. The lower clamp member 95 is moved upward. As a result, the clamping means 85 can clamp the plate-like workpieces W1, W2 arranged on the electrode 11 at the substantially central portion between the electrodes 11 by the upper clamp member 91 and the lower clamp member 95. ing.

  The energization heating device 81 is provided with one clamping means 85 for clamping the plate-like workpieces W1 and W2 between the electrodes 11, and is configured to clamp the plate-like workpieces W1 and W2 at one place between the electrodes 11. However, a plurality of clamping means may be provided to clamp the plate-like workpieces W1 and W2 at a plurality of locations between the electrodes 11.

  Also in the energization heating device 81 configured in this way, the clamp member 15 and the upper clamp member 91 are respectively moved upward and the lower clamp member 95 is moved downward. Two plate-like workpieces W1 and W2 are prepared, the two plate-like workpieces W1 and W2 are overlapped on the electrode 11, and the clamp member 15 is moved downward with respect to the two stacked plate-like workpieces W1 and W2. By moving, the pair of electrodes 11 is attached to the plate-like workpieces W1 and W2 by sandwiching the plate-like workpieces W1 and W2 between the electrode 11 and the clamp member 15.

  In the energization heating device 81, after the plate-like workpieces W1 and W2 are overlapped, before the two electrodes 11 are energized, the upper clamp member 91 is attached to the two overlapped plate-like workpieces W1 and W2. The plate-like workpieces W1 and W2 are clamped between the electrodes 11 by the upper clamp member 91 and the lower clamp member 95 by moving the lower clamp member 95 upward while moving the lower clamp member 95 upward. Is applied to heat the two plate-like workpieces W1 and W2.

  As described above, even when the energization heating device 81 is used, the sum of the cross-sectional areas of the plurality of plate workpieces W1 and W2 in the cross section orthogonal to the energization direction of the plurality of plate workpieces W1 and W2 is substantially constant in the energization direction. Since the Joule heat generated from the plurality of plate-like workpieces W1 and W2 can be made substantially equal in the energizing direction when energizing between the electrodes 11, the electrodes are relatively simple. Further, variations in the heating temperature of the plate-like workpieces W1, W2 can be suppressed. Even when the plate-like workpieces W1 and W2 formed in a non-rectangular shape are heated, variation in the heating temperature of the plate-like workpieces W1 and W2 can be suppressed.

  Further, in the energization heating device 81, a plurality of plate-like workpieces W1 and W2 are clamped at least at one or more places between the electrodes 11 using the clamping means 85, so that the plurality of plate-like members overlapped between the electrodes 11. It is possible to prevent a gap from being generated between the workpieces W1 and W2.

Next, a modified example of the plate-like workpiece heated in the energization heating apparatus according to the embodiment of the present invention will be described.
In this embodiment, the plate-like workpieces W1 and W2 that are prepared and overlapped so that the sum of the cross-sectional areas in the cross section perpendicular to the energization direction of the plate-like workpieces W1 and W2 are substantially constant in the energization direction are shown in FIG. In this way, the plate-like workpiece formed in a rectangular shape is cut by a point-symmetrical straight line L1 passing through the diagonal intersection C1, and is formed into the same right trapezoidal shape. However, the present invention is not limited to this. It is also possible to use a plate-like workpiece as shown in FIGS.

  FIG. 11 is a diagram illustrating first, second, and third modifications of the plate-like workpiece heated in the energization heating apparatus according to the embodiment of the present invention. As shown in FIG. 11 (a), the first and second plate-shaped workpieces formed in a rectangular shape are cut into the same right triangle by cutting along a point-symmetric linear line L5 passing through the diagonal intersection C1. The plate-like workpieces W1 and W2 are used to superimpose such that the sum of the cross-sectional areas in the cross section perpendicular to the energizing direction of the plate-like workpieces W1 and W2 is substantially constant in the energizing direction. Is also possible.

  In addition, as shown in FIG. 11 (b), the first and second plates are formed in the same shape by cutting a rectangular plate-shaped workpiece by a point-symmetric step-like line L6 passing through the intersection C1 of the diagonal line. Two plate-like workpieces W1 and W2 are used so that the sum of the cross-sectional areas in the cross sections orthogonal to the energizing direction of the plate-like workpieces W1 and W2 is superposed in the energizing direction in the energization heating devices 1, 61 and 81. As shown in FIG. 11 (c), the plate-shaped workpiece formed in a rectangular shape is cut by a point-symmetric curved line L7 passing through the diagonal intersection C1 to form the same shape. Using the first and second plate-like workpieces W1 and W2, the sum of the cross-sectional areas in the cross section perpendicular to the energizing direction of the plate-like workpieces W1 and W2 is substantially constant in the energizing direction. Like It is also possible to superimpose.

  In FIG. 11, two plate-like workpieces W1 and W2 formed by cutting a rectangular plate-like workpiece by point-symmetric lines L5, L6 and L7 passing through the diagonal intersection C1 are used. However, it is also possible to use two plate-like workpieces formed by cutting a plate-like workpiece formed in a parallelogram by a point-symmetric line passing through the intersection of diagonal lines into the same shape.

  FIG. 12 is a view showing a fourth modification of the plate-like workpiece heated in the energization heating apparatus according to the embodiment of the present invention. As shown in FIG. 12 (a), the first and second plates formed in the same isosceles trapezoidal shape by cutting a plate-like workpiece formed in a parallelogram by a point-symmetric linear line L8 passing through the diagonal intersection C2. Using the second plate-like workpieces W1 and W2, in the energization heating devices 1 and 81, as shown in FIG. 12B, the cross-sectional area in the cross section orthogonal to the energization direction of the plate-like workpieces W1 and W2 on the electrode 11 It is also possible to superimpose so that the sum of the two becomes substantially constant in the energization direction.

  FIG. 13 is a view showing a fifth modification of the plate-like workpiece heated in the energization heating apparatus according to the embodiment of the present invention. In FIG. 12, the plate-like workpiece formed in the parallelogram is cut to form the first and second plate-like workpieces W1, W2 in the same isosceles trapezoidal shape, which is shown in FIG. 13 (a). Thus, the length of the other opposite side between the parallel opposite sides having the same shape is obtained by cutting the plate-like workpiece formed in the parallelogram by a point-symmetrical straight line L9 passing through the diagonal intersection C3. Using the first and second plate-like workpieces W1 and W2 formed in different trapezoidal shapes, in the energization heating devices 1 and 81, the plate-like workpieces W1 and W2 are placed on the electrode 11 as shown in FIG. It is also possible to superimpose such that the sum of the cross-sectional areas in the cross section orthogonal to the energizing direction is substantially constant in the energizing direction.

  FIG. 14 is a view showing a sixth modification of the plate-like workpiece heated in the energization heating apparatus according to the embodiment of the present invention. As shown in FIG. 3A, the first and second plate-like workpieces W1 and W2 shown in FIG. 14 are point-symmetrical straight lines that pass through a diagonal intersection C1 of a rectangular plate-like workpiece. 14 are formed in the same right trapezoidal shape, but as shown in FIG. 14, the electrodes 11 in the energization heating devices 1 and 81 do not invert the first plate-like workpiece W1. The first and second plate-like workpieces W1 and W2 are overlapped so that the overlapping portion of the first and second plate-like workpieces W1 and W2 is rectangular, and the plate-like workpieces W1 and W2 are energized in the energizing direction. It is also possible to superimpose so that the sum of the cross-sectional areas in the orthogonal cross sections becomes substantially constant in the energization direction.

  In the electric heating devices 1, 61, 81, the stacked plate-like workpieces W1, W2 are formed in a non-rectangular shape having a certain thickness, but the stacked plate-like workpieces W1, W2 are formed. If the sum of the cross-sectional areas in the cross section perpendicular to the energizing direction of the plate-like workpieces W1 and W2 is formed and overlapped so as to be substantially constant in the energizing direction, the thickness of the plate-like workpieces W1 and W2 is It is also possible to use something that changes.

  FIG. 15 is a view showing a seventh modification of the plate-like workpiece heated in the energization heating apparatus according to the embodiment of the present invention. In FIG. 15, the plate-like workpiece is changed to the first embodiment of the present invention. It has shown in the state attached to the electric heating apparatus 1 which concerns. FIG. 15A is a schematic plan view of the electric heating device to which the plate-like workpiece is attached, and FIGS. 15B, 15C, and 15D are respectively in FIG. 15A. It is the side view of the said electricity heating apparatus seen from the Y15B direction, the Y15C direction, and the Y15D direction.

  As shown in FIG. 15, the sum of the cross-sectional areas of the first and second plate workpieces W11 and W12 in the cross section orthogonal to the energization direction of the plate workpieces W11 and W12 in the energization heating device 1 is substantially constant in the energization direction. When the first and second plate-like workpieces W11 and W12 that are formed in a rectangular shape and whose thickness changes in the longitudinal direction can be used.

  Even in such a case, since the Joule heat generated from the plurality of plate-like workpieces W11 and W12 can be made substantially equal in the energization direction when energizing between the electrodes 11, the plate-like workpieces W11 and W12 are relatively easy. The variation in the heating temperature can be suppressed.

  In addition, the plurality of plate-like workpieces heated in the energization heating according to the present embodiment is not limited to a metal plate-like workpiece such as a high-tensile steel plate, but may be a conductive plate-like workpiece having a predetermined electric resistance. It is also possible to use other plate-like workpieces made of resin, etc., but for a plurality of plate-like workpieces, the sum of the cross-sectional areas in the cross section perpendicular to the energizing direction of the plurality of plate-like workpieces is substantially constant in the energizing direction. What is formed and overlaid is used.

  The present invention is not limited to the illustrated embodiments, and it goes without saying that various improvements and design changes can be made without departing from the gist of the present invention.

  As described above, according to the present invention, when a plate-shaped workpiece formed in a non-rectangular shape is heated when the plate-shaped workpiece is heated by energization heating, the plate-shaped workpiece is substantially uniformly made relatively easily. Therefore, it may be suitably used for heating at the time of press forming of a high-strength steel plate used for a body constituting member such as a pillar or an impact bar.

1, 61, 81 Current heating device 11, 11a, 11b, 71, 71a, 71b Electrode 15, 91, 95 Clamp member 21, 22 Positioning member 30 Mold 31 Press molding device 85 Clamp means W1, W2, W11, W12 Plate -Shaped workpieces W1a, W1b, W2a, W2b

Claims (6)

An energization heating method for heating the plate-like workpiece by attaching and energizing a pair of electrodes spaced apart from each other to a conductive plate-like workpiece having a predetermined electrical resistance,
Preparing a plurality of the plate-like workpieces each formed in a predetermined shape;
Superposing the plurality of plate-like workpieces;
Attaching a pair of electrodes to the plurality of plate-like workpieces in a state where the plurality of plate-like workpieces are superposed;
Energizing between the electrodes;
Have
In the step of superimposing step said plurality of plate-shaped work of preparing the plurality of plate-shaped workpiece, and a constant sum of the cross-sectional area Te the current direction odor in a cross section perpendicular to the flowing direction of the plurality of plate-shaped workpiece The plurality of plate-like workpieces are prepared and overlaid so that
An electric heating method characterized by that. In the step of attaching the electrodes, the plurality of plate-shaped workpieces are sandwiched by the plurality of plate-shaped workpieces by sandwiching the plurality of plate-shaped workpieces with the electrodes and a clamp member disposed on the opposite side of the electrodes with the plurality of plate-shaped workpieces interposed therebetween. Install the electrodes
The energization heating method according to claim 1. Between the step of superimposing the plurality of plate-like workpieces and the step of energizing between the electrodes, the plurality of plate-like workpieces are at least between the electrodes by using clamping means for clamping the plurality of plate-like workpieces. Has a step of clamping in one or more places,
The energization heating method according to claim 1 or claim 2, characterized by that. A pair of electrodes spaced apart from each other, and provided with energizing means for heating the plurality of plate-like workpieces by attaching and energizing the pair of electrodes to a plurality of conductive plate-like workpieces having a predetermined electrical resistance, A state in which the plurality of plate-like workpieces are overlapped so that a sum of cross-sectional areas in a cross section perpendicular to the energization direction of the plurality of plate-like workpieces is substantially constant in the energization direction when the electrodes are energized. In the energization heating device that heats the plurality of plate workpieces by attaching a pair of electrodes to the plurality of plate workpieces and energizing,
The electrode is provided so as to extend in a direction substantially orthogonal to the energization direction and to be in contact with the entire direction orthogonal to the energization direction of the stacked plate-like workpieces.
An electric heating device characterized by that. A positioning member that engages with at least a part of a peripheral portion of the plurality of the plate-like workpieces that are overlapped to position the plurality of plate-like workpieces at a predetermined position;
The energization heating apparatus according to claim 4.   The hot press molding method which heats the said plate-shaped workpiece | work with the electric heating method of any one of Claim 1 to 3, and press-molds the said heated plate-shaped workpiece | work using a shaping | molding die.

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