JP2015160228A - Electrification heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrification heating apparatus for preventing dependency at the time when a steel plate is heated, by a simple mechanism.SOLUTION: An electrification heating apparatus enables the lower electrode 32 of a clamp mechanism 3 to move in the widthwise direction and fixes the upper electrode of the clamp mechanism 3 in the widthwise direction. Moreover, the electrification heating apparatus is composed of a pair of cam members 51 and 52 attached to individual electrodes 31 and 32, and is equipped with a cam mechanism 5 for converting driving force to lower the upper electrode 31 by a cylinder 33, into a driving force to move the lower electrode 32 widthwise outward.

Description

  The present invention relates to an electric heating apparatus that heats a blank material by energization, and more particularly to an electric heating apparatus that preheats a blank material to be subjected to hot press forming.

  For example, a frame of an automobile body is formed by press forming a steel plate. Since the vehicle body frame is required to have high strength in order to ensure the safety of passengers in the event of a collision, a high-tensile steel plate (high-tensile material) may be used as the material. However, the higher the strength (tension) of the steel plate, the greater the spring back after press forming and the lower the dimensional accuracy. As a method of avoiding such a problem, hot press forming is known in which press forming is performed in a state where a steel plate is heated to a predetermined temperature (for example, 900 ° C.) and softened. According to hot press forming, the spring back after press forming is suppressed, the dimensional accuracy is improved, and the heated steel sheet is cooled by coming into contact with the press forming mold, thereby being quenched. Strength is increased.

  As a kind of heating device that heats the steel plate in advance to perform hot press forming, electricity is passed between both clamp mechanisms with both ends of the steel plate clamped by a pair of clamp mechanisms, and the steel plate is heated by the current resistance at this time An electric heating device is known. In this case, since the steel plate is heated and softened and stretched, the central portion of the steel plate hangs down due to its own weight, which causes troubles in carrying out the steel plate from the current heating device and carrying it into the press forming device, There is a risk of degrading the positioning accuracy of the steel sheet in the forming apparatus. Then, in the electric heating apparatus of the following patent document 1, in a state where both ends of the steel plate are clamped by the pair of clamp mechanisms, the pair of clamp mechanisms are separated from each other during the electric heating, and the steel plate is pulled by heating. Prevents drooping in the center.

JP 2009-142854 A

  However, the current heating device of Patent Document 1 requires a drive unit for clamping the steel plate by the clamp mechanism and a drive unit for moving the clamp mechanism to the outside in the horizontal direction. The cost increases with it.

  In view of the circumstances as described above, the problem to be solved by the present invention is to prevent the central portion from sagging when a steel plate is heated by energization with a simple mechanism.

  In order to solve the above-mentioned problems, the present invention provides a pair of clamp mechanisms that are spaced apart from each other in the width direction and sandwich both ends of a heating scheduled region of a steel sheet, and a power source that applies a voltage between the pair of clamp mechanisms. Each clamp mechanism has a pair of clamp members arranged opposite to each other in the thickness direction of the steel plate, and a drive unit that relatively moves the pair of clamp members in the thickness direction, and at least one of the clamp members In the clamp mechanism, one clamp member is movable in the width direction, the other clamp member is fixed in the width direction, and includes a pair of cam members attached to each clamp member of the one clamp mechanism. Provided with a cam mechanism for converting a driving force for moving the pair of clamp members relative to each other in the thickness direction into a driving force for moving the one clamp member outward in the width direction. Providing resistance heating apparatus.

  Thus, in the electric heating apparatus according to the present invention, both the pair of clamp members sandwiching the steel plate are not moved in the width direction (the direction in which the pair of clamp mechanisms are separated), but only one clamp member is moved in the width direction. It was possible to move to. That is, in a state in which the steel plate is sandwiched between the pair of clamp members, only one clamp member is moved outward in the width direction (the side opposite to the side where the pair of clamp mechanisms are opposed to each other, the same applies hereinafter). By moving the end portion of the steel plate to the outside in the width direction by following the movement of the steel plate, the steel plate is pulled to prevent the central portion from sagging. According to this configuration, it is not necessary to move the other clamp member in the width direction, and the clamp member can be fixed in the width direction. In this case, a cam mechanism including cam members attached to each clamp member is provided, and when the pair of clamp members are relatively moved in the thickness direction by the drive unit, the cam members are pressed against each other, thereby driving force by the drive unit. Can be converted into a driving force for moving one of the clamp members outward in the width direction. Thereby, since clamping and tension | pulling of a steel plate can be performed by a common drive part, an apparatus can be simplified compared with the case where these are performed by a separate drive part.

  In the above-mentioned electric heating device, for example, a pair of clamp members of the one clamp mechanism can be provided with convex curved surfaces facing each other in the thickness direction, and the steel plates can be sandwiched between these convex curved surfaces. In this case, for example, after sandwiching the steel plates between the tops of the two convex curved surfaces, one clamp member is moved outward in the width direction, and the tops of the two convex curved surfaces are shifted in the same direction, so that both the clamp members are in the thickness direction. Therefore, the steel sheet can be pulled while being energized.

  As described above, according to the energization heating device of the present invention, the steel plate can be pulled by sliding one of the clamp members outward in the width direction with the driving force of the drive unit that causes the pair of clamp members to approach each other. It is possible to prevent the sag from being heated with a simple mechanism.

It is a side view of an electric heating device concerning one embodiment of the present invention. It is a side view which shows the state which clamped the steel plate with the clamp mechanism of the said electricity heating apparatus. It is a side view which shows the state which moved the lower electrode of the said electricity heating apparatus to the outer side. It is a side view of the electric heating apparatus which concerns on other embodiment. It is a side view which shows the state which moved the upper side electrode of the electricity heating apparatus of FIG. 4 to the outer side. It is a side view of the clamp mechanism of the electric heating apparatus which concerns on other embodiment. It is a side view which shows the state which moved the lower electrode of the electric heating apparatus of FIG. 6 to the outer side. It is a side view of the clamp mechanism of the electric heating apparatus which concerns on other embodiment.

  As shown in FIG. 1, the electric heating apparatus according to an embodiment of the present invention mainly includes an upper base 1, a lower base 2, a pair of clamp mechanisms 3, a power source 4, and a cam mechanism 5. The upper base 1 and the lower base 2 are fixed to a fixed frame (not shown). In the present embodiment, a case where the thickness direction of the steel plate W is set to the vertical direction (that is, the steel plate W is horizontally placed in the horizontal direction) is shown.

  The pair of clamp mechanisms 3 are arranged apart from each other in the width direction (left-right direction in FIG. 1), and are arranged at positions that sandwich both ends of the heating region of the steel plate W. In the illustrated example, the clamp mechanism 3 is provided in the vicinity of both ends of the steel plate W, whereby almost the entire area of the steel plate W is heated. Each clamp mechanism 3 includes a lower electrode 32 as one clamp member, an upper electrode 31 as the other clamp member, and a cylinder 33 as a drive unit that relatively moves both electrodes 31 and 32 in the vertical direction. .

  The upper electrode 31 can be moved up and down. In the illustrated example, the upper electrode 31 is fixed to the upper base 1 via the cylinder 33 and is moved up and down by moving the piston rod of the cylinder 33 back and forth. The upper electrode 31 is fixed in the width direction. A convex curved surface 31 a protruding downward is provided on the lower surface of the upper electrode 31. In the illustrated example, the convex curved surface 31a is constituted by a partial spherical surface.

  The lower electrode 32 is movable in the width direction. In the illustrated example, a slide base 6 that can freely move in the width direction is provided on the lower base 2, and the lower electrode 32 is fixed on the slide base 6. The slide table 6 is urged inward in the width direction by an urging means (not shown), and movement toward the inner side in the width direction is restricted by a stopper (not shown) at the initial position shown in FIG. The lower electrode 32 is fixed in the vertical direction. A convex curved surface 32 a protruding upward is provided on the upper surface of the lower electrode 32. In the illustrated example, the convex curved surface 32a is constituted by a partial spherical surface.

  A power supply 4 is connected to the pair of clamp mechanisms 3. In the illustrated example, the positive electrode of the power source 4 is connected to both electrodes 31 and 32 of one clamp mechanism 3, and the negative electrode of the power source 4 is connected to both electrodes 31 and 32 of the other clamp mechanism 3.

  The cam mechanism 5 is attached to the upper electrode 31, and the upper cam member 51 that moves up and down integrally therewith, and the lower cam that is attached to the lower electrode 32 via the slide base 6 and moves in the width direction integrally therewith. And a member 52. The cam mechanism 5 converts a driving force that lowers the upper electrode 31 into a driving force that moves the lower electrode 32 outward in the width direction. In the illustrated example, the lower cam member 51 is provided with a cam surface 51a inclined upward in the width direction on the lower surface, and the upper surface of the lower cam member 52 is parallel to the cam surface 51a of the upper cam member 51. In addition, a cam surface 52a facing in the vertical direction is provided.

  Hereinafter, a procedure for heating the steel sheet W using the above-described electric heating apparatus will be described.

  First, as shown in FIG. 1, a steel plate W (blank material) is placed on the convex curved surface 32 a of the lower electrode 32 with the upper electrode 31 raised to the upper end position by the cylinder 33.

  Next, the upper electrode 31 is lowered by the cylinder 33, and the steel plate W is sandwiched between the top and bottom of the convex surface 31a of the upper electrode 31 and the top of the convex surface 32a of the lower electrode 32 as shown in FIG. To do. In this state, a voltage is applied between the clamp mechanisms 3 by the power source 4 to energize the steel sheet W. Specifically, an energization path of the power source 4 → the electrodes 31 and 32 of the one clamp mechanism 3 → the steel plate W → the electrodes 31 and 32 of the other clamp mechanism 3 → the power source 4 is formed. Thereby, the steel plate W is heated by the energization resistance.

  The upper electrode 31 is further lowered by the cylinder 33 while energizing the steel plate W as described above. As a result, as shown in FIG. 3, the cam surface 51a of the upper cam member 51 is pressed against the cam surface 52a of the lower cam member, and both the cam surfaces 51a and 52a slide while the lower cam member 52 has a width. Accordingly, the lower cam member 52, the slide base 6, and the lower electrode 32 are integrally moved outward in the width direction. At this time, due to the contact resistance between the convex curved surface 32a of the lower electrode 32 and the steel plate W, the end of the steel plate W is pulled outward in the width direction following the lower electrode 32, and tension is applied to the steel plate W. As described above, by applying tension to the steel sheet W while applying current to the steel sheet W, it is possible to prevent the central portion of the steel sheet W softened by heating from sagging.

  At this time, by sandwiching the steel plate W between the convex curved surfaces 31a and 32a of the electrodes 31, 32, the upper electrode 31 can be further lowered after the steel plate W is sandwiched. Specifically, after the steel plate W is sandwiched between the tops of the convex curved surfaces 31a and 32a of both the electrodes 31 and 32, the lower electrode 32 is shifted outward in the width direction via the cam mechanism 5, thereby The top of the convex curved surface 31a of the lower electrode 32 is retracted from directly below the top of the convex curved surface 31a, and further lowering of the upper electrode 31 is allowed. Thereby, it is possible to pull the steel sheet W by moving the lower electrode 32 outward in the width direction while sandwiching and heating the steel sheet W.

  In the above process, before the steel plate W is sandwiched (from the state of FIG. 1 to the state of FIG. 2), it is an empty stroke that only moves the upper electrode 31, so that it is lowered at a relatively high speed. The cycle time is shortened. On the other hand, after sandwiching the steel plate W (after the state of FIG. 2), it is necessary to move the lower electrode 32 outward in the width direction in accordance with the minute extension amount due to the heating of the steel plate W, so the upper electrode 31 is compared. It is preferable to descend at a slow speed. From the above, it is preferable that the lowering speed of the upper electrode 31 after sandwiching the steel sheet W is slower than the lowering speed of the upper electrode 31 before sandwiching the steel sheet W.

  When the steel plate W is heated to a predetermined temperature, the upper electrode 31 and the upper cam member 51 are raised by the cylinder 33. As a result, the pressing force of the upper cam member 51 on the lower cam member 52 is released, and the lower cam member 52 is returned to the initial position shown in FIG. Thereafter, the heated steel sheet W is carried out from the energization heating device, is carried into a hot press forming device, and is subjected to press forming.

  The present invention is not limited to the above embodiment. For example, when the steel plate W is stretched while being heated, a means for making the steel plate W follow the movement of the lower electrode 32 outward in the width direction may be provided in the lower electrode 32. For example, the following means can be configured by making the friction coefficient between the lower electrode 32 and the steel plate W larger than the friction coefficient between the upper electrode 31 and the steel plate W. In this case, for example, the surface of the convex surface 32a of the lower electrode 32 is subjected to a roughening process, or a dimple-like minute convex portion or a minute concave portion is formed, whereby the friction between the lower electrode 32 and the steel plate W is achieved. The coefficient can be increased. In addition, by making the curvature of the convex curved surface 32a of the lower electrode 32 larger than the curvature of the convex curved surface 31a of the upper electrode 31, the following means can be configured.

  Moreover, although the case where the lower electrode 32 is moved outward in the width direction has been described in the above embodiment, the present invention is not limited thereto, and the upper electrode 31 may be moved outward in the width direction. For example, in the embodiment shown in FIG. 4, the lower electrode 32 and the lower cam member 52 are fixed to the lower base 2. On the other hand, the cylinder 33 is slidably attached to the slide rail 7 provided on the upper base 1, whereby the cylinder 33, the upper electrode 31, and the upper cam member 51 are movable in the width direction. The cam surfaces 51a and 52a of both the cam members 51 and 52 are inclined downward toward the outer side in the width direction.

  When the upper electrode 31 is further lowered by the cylinder 33 from the state in which the steel plate W is sandwiched between the electrodes 31 and 32 in the above-described energization heating device, the cam surface 51a of the upper cam member 51 becomes the cam surface of the lower cam member 52. The upper cam member 51, the upper electrode 31, and the cylinder 33 are integrally moved outward in the width direction by being pressed against 52 a (see FIG. 5). Accordingly, the end of the steel plate W is pulled outward in the width direction following the upper electrode 31, and the steel plate W is stretched.

  In the embodiment shown in FIG. 6, a damper 8 is provided between the lower electrode 32 and the slide base 6 to allow the lower electrode 32 to descend when a pressure of a predetermined value or more is applied. In this case, when the piston rod of the cylinder 33 is further protruded from the state in which the steel plate W is sandwiched between the electrodes 31 and 32, the damper 8 is shortened and further lowering of the upper electrode 31 is allowed. 7, the cam surface 51a of the upper cam member 51 is pressed against the cam surface 52a of the lower cam member 52, and the lower cam member 52, the damper 8 and the lower The side electrode 32 moves outward in the width direction. In this case, it is not necessary to provide convex surfaces on both the electrodes 31, 32, and one or both can be flat surfaces. In the illustrated example, the upper surface of the lower electrode 32 is a flat surface 32b. The position where the damper is provided is not limited to the above. For example, as shown in FIG. 8, a pressure of a predetermined value or more is provided between the upper electrode 31 and the lifting plate 9 provided at the lower end of the piston rod of the cylinder 33. A damper 8 may be provided that allows the upper electrode 31 to be lifted with respect to the lifting plate 9 when the is applied.

  In the above-described embodiment, the case where the cam mechanism 5 or the like that slides the lower electrode 32 or the upper electrode 31 to the outside is provided in both the pair of clamp mechanisms 3 is not limited thereto. 5 etc. may be provided only in one clamp mechanism 3.

  Further, in the above-described embodiment, the case where each of the pair of clamp members of each clamp mechanism 3 is an electrode connected to the power source 4 is shown, but not limited to this, one of the pair of clamp members is connected to the power source 4. It is good also as a receiving part without connecting with the power supply 4 and making the other into an electrode.

DESCRIPTION OF SYMBOLS 1 Upper base 2 Lower base 3 Clamp mechanism 4 Power supply 5 Cam mechanism 6 Slide stand 31 Upper electrode (the other clamp member)
31a Convex surface 32 Lower electrode (one clamp member)
32a Convex surface 33 Cylinder (drive unit)
51 Upper cam member (the other cam member)
51a Cam surface 52 Lower cam member (one cam member)
52a Cam surface W Steel plate

Claims (1)

A pair of clamp mechanisms that are spaced apart in the width direction and sandwich both ends of the heating scheduled region of the steel sheet, and a power source that applies a voltage between the pair of clamp mechanisms,
Each clamp mechanism has a pair of clamp members disposed opposite to each other in the thickness direction of the steel plate, and a drive unit that relatively moves the pair of clamp members in the thickness direction,
In at least one of the clamp mechanisms, one clamp member is movable in the width direction, and the other clamp member is fixed in the width direction,
It consists of a pair of cam members attached to each clamp member of the one clamp mechanism, and a driving force that causes the pair of clamp members to move relative to each other in the thickness direction by the drive unit, and the one clamp member in the width direction. An energization heating device provided with a cam mechanism that converts the driving force to move outward.

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