JP4900908B2 - Heating apparatus and method for press molding - Google Patents

Description

  The present invention relates to an apparatus and method for heating a workpiece prior to press molding.

  In press molding of work materials made of materials such as high tensile strength steel, magnesium alloy, titanium alloy or aluminum, which are frequently used in automobiles, home appliances and electronic parts, warm press molding or hot press molding (hereinafter referred to as “warm / hot press molding”). In many cases, a method called “hot press molding” is employed. That is, the entire workpiece is heated to a high temperature suitable for molding, and the high temperature workpiece is pressed. Conventionally, a batch furnace heating method in which a plurality of workpieces are heated in a furnace such as an electric furnace or a gas furnace has been widely adopted as a heating method of the workpieces for warm / hot press forming. However, in order to prevent oxidation of the workpiece in the furnace, it is necessary to use an inert gas furnace or a vacuum furnace, and the equipment cost is high. Also, batch furnace heating cannot be performed in-line on a mass production line. Further, the heating time often takes several minutes to several tens of minutes, and it is difficult to heat the workpiece to a desired temperature in a short time such as a second order.

Therefore, as a heating method that can be used in-line and can heat the workpiece to a desired temperature in a short time on the order of seconds, an energization heating method in which a current is passed through the workpiece is disclosed in Patent Document 1. In this method, an electrode is brought into contact with a plurality of portions of the workpiece, and the workpiece is heated by flowing a large current directly from the electrodes to the workpiece.
JP 2005-1316565 A

  Although the above-described conventional heating method has an advantage that it can be used in-line, there is a problem that it is difficult to heat a desired region of the workpiece regardless of the planar shape of the workpiece. This problem can be divided into the following two aspects.

  The first side surface is a problem that it is difficult to heat the entire region of the workpiece to a uniform temperature regardless of the planar shape of the workpiece. In general, in warm / hot press molding, it is required to heat the entire region of the workpiece to a uniform temperature. When the workpiece is a plate having a rectangular planar shape, the entire region of the workpiece can be heated to a uniform temperature by the above-described conventional heating method. However, when the work piece is a plate having an irregular shape or a complicated shape such as a flat shape other than a rectangle or a hole formed inside, the current of the work piece can be reduced by the conventional electric heating method. The density becomes non-uniform, it is difficult to heat the entire region of the workpiece to a uniform temperature, and sparking may occur during energization.

  The second aspect is that only a specific partial region of the workpiece cannot be selectively heated by the conventional energization heating method. However, if it is possible to selectively heat only a desired partial region of the workpiece, for example, the possibility of a new processing method as described below opens. That is, materials that are difficult to be cold-pressed, such as high strength steel, are generally formed by a warm / hot press method. However, in cold press forming, if it is possible to selectively heat only a specific partial region of the workpiece and selectively plastically deform only the specific partial region, cold forming such as high strength steel is possible. Therefore, it is possible to adopt cold press forming by progressive processing even for materials that are difficult to process. Alternatively, even in hot / hot press molding, local embossing, local punching, or local drawing can be performed more easily.

  Furthermore, as a problem of conventional energization heating, there is also a point that it is difficult to apply to a workpiece having a low electrical resistance.

  Accordingly, it is an object of the present invention to be able to be used in-line in a workpiece heating apparatus and method for press molding and to heat a desired region of the workpiece.

  Another object of the present invention is to make it possible to heat the entire region of the workpiece to a uniform temperature regardless of the planar shape of the workpiece.

  Another object of the present invention is to enable selective heating of specific partial areas of the workpiece.

  Still another object of the present invention is to enable heating of a workpiece having a low electrical resistance.

  The apparatus for heating a workpiece for press molding according to the first aspect of the present invention can insert a workpiece before press molding between them, and one of them approaches or separates from the other. At least two heating plates that can be moved, heating means for heating each of the heating plates to a substantially uniform temperature over at least a region acting on the workpiece, and control means for controlling the heating means With. When the heating plate is heated and the workpiece is inserted between the heating plates, the workpiece is sandwiched so that one of the heating plates approaches the other and is in close contact with both surfaces of a predetermined region of the workpiece. . And the state which the heating plate sandwiched the workpiece is maintained for a predetermined time.

  According to this heating apparatus, each of at least two heating plates is heated to a substantially uniform temperature over at least a region (for example, over the entire region) acting on the workpiece, and the workpiece before press molding is performed. Sandwich from both sides. When the workpieces are sandwiched, the heating plate is in close contact with both surfaces of the predetermined region of the workpieces, and this sandwich state is maintained for a predetermined time. As a result, a predetermined region of the workpiece can be heated regardless of the planar shape of the workpiece. Moreover, even if a workpiece is a material with a low electrical resistivity, a workpiece can be heated favorably. In addition, the heating device can be used in-line by being incorporated in a production line (typically immediately before a press molding machine). When the workpieces are sandwiched, it is preferable to maintain a close contact state by applying a pressing force to the workpieces so as not to deform the workpieces. Thereby, the oxidation of the surface of the workpiece is also suppressed.

  In one embodiment, the heating plate adheres to both sides of the entire area of the workpiece when the workpiece is sandwiched. As a result, regardless of the planar shape of the workpiece, the entire area of the workpiece can be heated to a substantially uniform temperature.

  In another embodiment, the heating plate adheres to both sides of a particular partial region of the workpiece when the workpiece is sandwiched. As a result, the specific partial region of the workpiece can be selectively heated.

  As a heating method of the heating plate, there can be employed energization heating in which a current is passed through the heating plate itself, induction heating in which an induction electric field is applied to the heating plate itself, or a heating method using a heating wire heater embedded in the heating plate.

  In one embodiment, each of the heating plates has a rectangular parallelepiped shape and is heated by a method of electric heating or induction heating. Since the heating plate is a rectangular parallelepiped, at least a region (for example, the entire region) acting on the workpiece can be heated to a uniform temperature by a method of current heating or induction heating. In addition, if the method of current heating or induction heating is used, a large power can be input to the region of the heating plate, so that the heating plate can be heated at high speed. As a result, the desired region of the workpiece can be heated in a short time.

  According to another aspect of the present invention, there is provided a method of heating a workpiece for press molding, wherein each of at least two heating plates has a substantially uniform temperature over at least an area acting on the workpiece (eg, over the entire area). A heating step for heating the plate, an insertion step for inserting a workpiece before press molding between the heating plates, and after the insertion step, one of the heating plates is brought close to the other so that the heating plates are processed A sandwiching step of sandwiching the workpieces so as to be in close contact with both sides of a desired region of the material; and a maintaining step of maintaining a sandwiched state of the workpieces by a heating plate for a predetermined time. When the workpieces are sandwiched, it is preferable to maintain a close contact state by applying a pressing force to the workpieces so as not to deform the workpieces.

  According to this method, a predetermined region of the workpiece can be heated regardless of the planar shape of the workpiece. Moreover, even if a workpiece is a material with a low electrical resistivity, a workpiece can be heated favorably. This heating method can also be used in-line in the production line (typically just before the press molding step).

  According to one aspect of the present invention, a desired region of a workpiece before press molding can be heated and used in-line. In particular, when the heating plate is in close contact with both sides of the entire region of the workpiece, the entire region of the workpiece can be heated to a uniform temperature regardless of the planar shape of the workpiece. On the other hand, when the heating plate is in close contact with both surfaces of the specific partial region of the workpiece, the specific partial region of the workpiece can be selectively heated.

  In addition, according to the present invention, a workpiece having a low electrical resistance can be heated.

  FIG. 1 shows a configuration of a main part of a heating apparatus for a workpiece for press molding according to a first embodiment of the present invention. FIG. 2 shows the overall configuration of this heating apparatus.

  As shown in FIG. 1, two heating plates 10 and 12 (upper heating plate 10 and lower heating plate 12) each having a rectangular parallelepiped (the planar shape is rectangular) are the main surfaces (the widest surface). Specifically, the upper heating plate 10 and the lower heating plate 12 are arranged vertically so that the lower surface of the upper heating plate 10 and the upper surface of the lower heating plate 12 face each other in parallel. As shown in FIG. 2, the two heating plates 10 and 12 are incorporated in a press machine 40 for this heating device (separate from the press machine for press molding the workpiece 14). The two heating plates 10 and 12 are moved by the press machine 40 so that one of them approaches or moves away from the other (that is, the space between the heating plates 10 and 12 becomes narrower or wider). ing.

  The workpiece 14 to be heated by this heating apparatus is typically an individual plate piece cut in advance from a wide base plate material, and the planar shape thereof is various. When such a workpiece 14 has a flat plate shape before press molding, it is held by the fingers 16A and 16B of the workpiece conveying device (not shown) and placed on the lower heating plate 12. It has become. When the heating of the workpiece 14 by the heating plates 10 and 12 is finished, the workpiece 14 on the lower heating plate 12 is again gripped by the fingers 16A and 16B and taken out. Yes. Compared to the workpiece 14, the heating plates 10 and 12 are clearly larger in planar size. Therefore, when the heating plates 10 and 12 sandwich the workpiece 14 as will be described later, the heating plates 10 and 12 are not covered. The entire periphery of the workpiece 14 is surrounded.

  As a heating method for the heating plates 10 and 12, a method such as energization heating, induction heating, or heating by a heating wire heater can be employed. In this embodiment, an energization heating method is employed as an example.

  Electrodes 20 </ b> A and 20 </ b> B for flowing a large current for energization heating from the outside to the upper heating plate 10 on both opposite side surfaces of the upper heating plate 10 (for example, two side surfaces having a smaller area among the four side surfaces). Are joined. Similarly, electrodes 22A and 22B are joined to the entire area of the opposite side surfaces of the lower heating plate 12, respectively. Each of these electrodes 20A, 20B, 22A, 22B covers the entire area of each side surface of the heating plates 10, 12 on which it is provided. As shown in FIG. 2, current lines 62 and 64 for supplying a heating current from the power supply circuit 60 are connected to the heads 24A, 24B, 26A and 26B of the electrodes 20A, 20B, 22A and 22B.

  In any of the heating plates 10 and 12, the heating current enters the heating plates 10 and 12 from the electrodes 20A and 22A on one side, and flows in the heating plates 10 and 12 at a uniform current density over the entire cross section. Then, it flows out to the opposite electrodes 20B, 22B. Therefore, the entire area of any of the heating plates 10 and 12 is heated to a substantially uniform temperature.

  The material of the heating plates 10 and 12 is a metal having a certain degree of electrical resistivity, which easily generates Joule heat when energized. On the other hand, the electrodes 20A, 20B, 22A, and 22B are metals that have a lower electrical resistivity than the heating plates 10 and 12 and are not heated much even when a large current flows. For joining the heating plates 10 and 12 to the electrodes 20A, 20B, 22A and 22B, a method capable of reducing the electrical resistance at the joining surface to a negligible level, for example, a pressure bonding method in which the bolt is firmly fastened and pressed with a bolt, or welding. A metallurgical joining method such as can be employed.

  The electrodes 20A, 20B, 22A, and 22B are also provided with through holes 28A, 28B, 30A, and 30B, respectively, through which the columns 46A and 46B shown in FIG. 2 are passed. The inner diameters of the through holes 28A, 28B, 30A, 30B are somewhat larger than the outer diameters of the columns 46A, 46B so that the heating plates 10, 12 do not deform even if the heating plates 10, 12 are thermally expanded. Between the holes 28A, 28B, 30A, 30B and the columns 46A, 46B, there are gaps large enough to absorb the thermal expansion of the heating plates 10, 12.

  As shown in FIG. 2, a heat insulating / insulating plate 52 is laid on the upper surface of the base 42 of the press machine 40 for the heating device. Further, on the upper surface of the base 42, guide members for controlling the positions of the heating plates 10 and 12, for example, two columns 46A and 46B made of an insulating material are erected in the vertical direction. The lower heating plate 12 is placed on the heat insulating / insulating plate 52, and the columns 46A and 46B are passed through the through holes 30A and 39B of the electrodes 22A and 22B at both ends of the lower heating plate 12, respectively. The heat insulating / insulating plate 52 insulates between the lower heating plate 12 and the base 42 and electrically insulates.

  The upper heating plate 10 is disposed above the lower heating plate 12, and the columns 46A and 46B are passed through the through holes 28A and 28B of the electrodes 20A and 20B at both ends of the upper heating plate 10, respectively. The upper heating plate 10 can move in the vertical direction along the columns 46A and 46B. Between the lower heating plate 12 and the upper heating plate 10, push-up members, for example, coiled springs 48 </ b> A and 48 </ b> B, are arranged to push the upper heating plate 10 upward. These springs 48A and 48B are fitted to the columns 46A and 46B. Stoppers 50A and 50B are attached to the upper ends of the columns 46A and 46B. The stoppers 50A and 50B prevent the upper heating plate 10 from rising further and prevent the upper heating plate 10 from falling off the support columns 46A and 46B.

  As shown in FIG. 2, the slide 44 of the press machine 40 is located directly above the upper heating plate 10. A heat insulating / insulating plate 54 is attached to the lower surface of the slide 44. As shown in the figure, when the slide 44 is located at the top dead center, the slide 44 is separated from the upper heating plate 10, and the upper heating plate 10 is located at the highest point shown in the figure by the action of the springs 48A and 48B. And the lower heating plate 12 have a large space for taking the workpiece 14 in and out. When the slide 44 is lowered, first, the heat insulating / insulating plate 54 on the lower surface of the slide 44 comes into contact with the upper surface of the upper heating plate 10 and then the upper heating plate 10 is pushed down. The upper heating plate 10 descends with the lower heating plate 12 in a parallel posture. When the upper heating plate 10 reaches the lowest position, the upper heating plate 10 and the lower heating plate 12 are in close contact with both surfaces of the entire region of the workpiece 14. Thereafter, when the slide 44 is lifted, the upper heating plate 10 is also lifted by the action of the springs 48A and 48B and stops at the highest point shown in the figure. The heat insulating / insulating plate 54 insulates and electrically insulates between the upper heating plate 10 and the slide 44.

  The heating device is further provided with a control device 66 for controlling the press machine 40, the power supply circuit 60, and the workpiece conveying device. Under the control of the control device 66, the operation of the heating device is executed in the procedure described below.

  FIG. 3 shows an operation flow of one cycle of the heating process of the workpiece 14 performed by the heating device.

  As shown in FIG. 3, in step S1, the upper heating plate 10 is positioned at the highest point. In step S2, a large current is supplied to each of the upper heating plate 10 and the lower heating plate 12, and the heating plates 10 and 12 are heated to a predetermined heating temperature. Here, the heating temperature of the heating plates 10 and 12 is a temperature somewhat higher than the expected heating temperature of the workpiece 14 (temperature suitable for press molding), for example, about 50 to 100 ° C. Since the scheduled heating temperature of the workpiece 14 varies depending on the production line, the heating temperature of the heating plates 10 and 12 varies accordingly. For example, in a line for warm press forming a high strength steel sheet for automobiles at a temperature of about 900 ° C., the heating temperature of the heating plates 10 and 12 is somewhat higher than the planned heating temperature 900 ° C. of the workpiece 14, for example, 950 ° C. Set to degree. In addition, the line to which the present invention can be applied includes, for example, a line for performing a dike etching method in which a high strength steel sheet is press-formed at a temperature of a martensite transformation point of 650 ° C. or higher, and a temperature of about 300 ° C. There are various types such as a line for press-molding a magnesium plate and a line for press-molding an aluminum plate at a temperature of 400 ° C. or higher. In any case, the heating temperature of the heating plates 10 and 12 is determined according to the expected heating temperature of the workpiece 14. In step S2, the heating plates 10 and 12 can be raised to the heating temperature in a very short time of the order of seconds. As described above, since each of the heating plates 10 and 12 is a rectangular parallelepiped, it is heated almost uniformly to the heating temperature as a whole.

  As soon as the heating plates 10 and 12 are heated to the above heating temperature, the plate-shaped workpiece 14 before pre-molding is held by the fingers 16A and 16B and placed on the lower heating plate 12 in step S3. The fingers 16 </ b> A and 16 </ b> B are immediately retracted from between the heating plates 10 and 12 when the workpiece 14 is placed on the lower heating plate 12.

  Immediately thereafter, in step S4, the slide 44 is lowered to push down the upper heating plate 10, and the workpiece 14 is sandwiched between the two heating plates 10 and 12. Subsequently, in step S5, the state in which the workpiece 14 is sandwiched between the two heating plates 10 and 12 is maintained for a predetermined heating time. In the meantime, a slight pressing force that does not deform the workpiece 14 is applied to the upper heating plate 10. By this pressurization, the main surfaces of both the heating plates 10 and 12 are brought into close contact with both surfaces of the entire region of the workpiece 14, and heat from both the heating plates 10 and 12 is transmitted to the workpiece 14 to be processed 14. And both surfaces of the workpiece 14 are shielded from the air to prevent oxidation of both surfaces of the workpiece 14. Since the workpiece 14 is sandwiched between the heating plates 10 and 12 heated to a uniform temperature, the entire area of the workpiece 14 is also heated to a uniform temperature.

The magnitude of the applied pressure in the side-switched state is such that the workpiece 14 is not deformed, the oxidation of both surfaces of the workpiece 14 can be prevented, and the workpiece 14 is predetermined in a desired short time. It is selected from the viewpoint of being able to be heated up to the heating temperature. For example, when the workpiece 14 is a high tensile strength steel plate and the heating temperature is about 900 ° C., the workpiece 14 is deformed when a pressure of 600 kg / cm ² or more is applied. The applied pressure may be about 400 to 500 kg / cm ² or less, for example, about 300 kg / cm ² , or about 50 kg / cm ² . In fact, when the inventors experimented, even with a weak pressure of about 100 kg / cm ^2, it was sandwiched between both heating plates 10 and 12 preheated to about 950 ° C., and the time was shorter than 10 seconds. In time, the high strength steel sheet as the workpiece 14 could be heated to a predetermined heating temperature of about 900 ° C.

  After maintaining the sandwich state for a predetermined time, in step S6, the slide 44 is raised and the upper heating plate 10 is raised. Subsequently, immediately at step S7, the workpiece conveying device (not shown) grips the heated workpiece 14 with its fingers 16A, 16B, removes it from the lower heating plate 10, and immediately, The workpiece 14 is set in a press machine (not shown) for press molding. Thereafter, in a press machine for press molding, press molding of the workpiece 14 at a heating temperature is performed.

  One cycle of the heating operation as described above is repeated for each workpiece 14.

  According to the processing apparatus and method according to the first embodiment described above, the workpiece 14 can be heated in-line, and can be heated in a shorter time than the conventional batch furnace heating. The temperature of 14 can be heated to a uniform temperature. Moreover, even if the workpiece 14 is a material with a low electrical resistance, it can be heated. Further, in the energization heating method in which a current is directly applied to the workpiece 14 as disclosed in Patent Document 1, both ends of the workpiece 14 are not pulled outward in accordance with the thermal expansion of the workpiece 14 during energization heating. Then, the workpiece 14 may be deformed by thermal expansion. On the other hand, according to the processing apparatus and method according to the first embodiment, since the workpiece 14 can be thermally expanded between both the heating plates 10 and 12, there is no possibility that the workpiece 14 is deformed during heating. .

  As a modification, as described above, the heating plates 10 and 12 may be heated by a method such as induction heating or heating with a heating wire heater. For example, by providing a high-frequency coil that applies an induction electric field to the heating plates 10 and 12 in the vicinity of the heating plates 10 and 12, the heating plates 10 and 12 can be heated by an induction heating method. Alternatively, by embedding a heating wire heater in the heating plates 10 and 12, the heating plates 10 and 12 can be heated by the heating wire heater.

  FIG. 4 shows the structure of the two heating plates used in the heating device according to the second embodiment of the present invention. In particular, FIG. 4A is a cross-sectional view showing the positional relationship between the two heating plates. FIG. 4B is a plan view showing a planar structure example of each heating plate. FIG. 5: is sectional drawing which shows the example of the press molding result of a heating workpiece by the heating apparatus concerning this 2nd Embodiment. FIG. 6 is a front view showing the overall configuration of the heating apparatus according to the second embodiment. In FIG. 6, elements that are substantially the same in function as those shown in FIG. 2 are given the same reference numerals as those in FIG. 2, and redundant descriptions are omitted.

  The heating device according to the first embodiment described above heats the workpiece to a uniform temperature as a whole, whereas the heating according to the second embodiment shown in FIGS. 4 to 6. The apparatus selectively heats a specific partial region of the workpiece.

  As shown in FIG. 4, two heating plates 70 and 72 (an upper heating plate 70 and a lower heating plate 72) are arranged facing each other in parallel. As shown in FIG. 6, the two heating plates 70 and 72 are incorporated in the press machine 40 for the heating device so that one moves toward and away from the other. A workpiece 74 is inserted between the two heating plates 70 and 72. After the workpiece 74 is heated by this heating device, only specific partial regions 80A and 80B therein are selectively press-molded as shown in FIG.

  As shown in FIG. 4, convex portions 76A, 76B, and 76C are formed on the main surfaces of the two heating plates 70 and 72 so as to come into contact with only the press-scheduled partial regions 80A and 80B of the workpiece 74. ing. These convex portions 76A, 76B, 76C, 78A, 78B are formed integrally with the main body portions of the respective heating plates 70, 72. As shown in FIG. 4A, each of the convex portions 76A, 76B, 76C, 78A, 78B has a mesa shape (trapezoidal shape), and its surface is in close contact with both surfaces of the workpiece 74. Be flat so that you can. Further, as shown in FIG. 4B, the planar shapes of the convex portions 76A, 76B, 76C, 78A, and 78B correspond to the planar shapes of the press work scheduled partial regions 80A and 80B of the workpiece 74, respectively.

  As shown in FIG. 4B, the planar shape of the heating plates 70, 72 themselves is the planar arrangement of the convex portions 76A, 76B, 76C, 78A, 78B (that is, the press work scheduled partial region 80A of the workpiece 74). , 80B planar arrangement). In the example shown in FIG. 4B, the upper heating plate 70 has a triangular planar shape corresponding to the arrangement of the three convex portions 76A, 76B, 76C (in FIG. Only the plate 70 is shown, but the lower heating plate 70 is the same).

  As a heating method of the heating plates 70 and 72, a method such as energization heating, induction heating, or heater heating using a heating wire heater can be employed. However, the heating plates 70 and 72 have convex portions 76A, 76B, 76C, 78A, and 78B, and the planar shape thereof is not rectangular, and in short, does not have a simple rectangular parallelepiped shape. Therefore, the heating plates 70 and 72 are generally heated to a uniform temperature, or at least the convex portions 76A, 76B, 76C, 78A, and 78B that are in contact with the workpiece 74 are heated to a uniform temperature. Is difficult by electric heating or induction heating. Therefore, in this embodiment, heating by a heating wire heater is employed. In order to be able to heat the heating plates 70 and 72 to a uniform temperature as a whole, or in order to heat at least the convex portions 76A, 76B, 76C, 78A and 78B to a uniform temperature, FIG. As shown in B), heating wire heaters 82 and 83 are stretched over each of the heating plates 70 and 72 with a substantially uniform density over the entire area. When the heating method using a heating wire heater is adopted, the material of the heating plates 70 and 72 may be a metal or an insulator.

  As shown in FIG. 6, a lower heating plate 72 is fixed on a base 72 of a press machine 40 for a heating device via a heat insulating / insulating plate 52. Also on the side surface of the lower heating plate 72, heat insulating / insulating plates 73A and 73B are provided. Further, the upper heating plate 70 is supported on the slide holders 90A and 90B movable along the columns 46A and 46B via the heat insulating / insulating plates 91A and 91B. As in the case of the first embodiment already described, the upper heating plate 70 is lowered or raised by the lowering and raising of the slide 44. If the heating plates 70 and 72 themselves have electrical insulation properties, or if the heating plates 70 and 72 are insulated from the electric heaters 82 and 83 inside the heating plates 70 and 72, they are insulated / insulated. The plates 52, 54, 73A, 73B, 91A, 91B may not have electrical insulation. A workpiece conveying device, for example, two conveying bars 92A and 92B have two fingers 94A and 94B, and grip the workpiece 74 with the fingers 94A and 94B, and between the heating plates 70 and 72. And placed on the lower heating plate 72. In FIG. 6, a power supply device and wiring for supplying a heating current to the heating plates 70 and 72 are not shown.

  The operation of one cycle of the heating process of the workpiece 74 by the heating device is basically the same as the operation already described with reference to FIG. That is, first, the heating plates 70 and 72 are heated to a predetermined heating temperature (FIG. 3, S1-S2). Immediately thereafter, the flat plate-like workpiece 74 before pressing is placed on the lower heating plate 72 (S3). Immediately thereafter, the heating plates 70 and 72 sandwich the workpiece 74 (S4) and heat the workpiece 74 (S5).

  When the heating plates 70, 72 sandwich the workpiece 74, only the convex portions 76 A, 76 B, 76 C, 78 A, 78 B of the heating plates 70, 72 are the upper and lower surfaces of the pressing target partial regions 80 A, 80 B of the workpiece 74. Will be in close contact. As a result, only the press planned partial regions 80A and 80B of the workpiece 74 are selectively heated. Immediately thereafter, by pressing only the press-scheduled partial areas 80A and 80B, as shown in FIG. 5, it is possible to selectively press-mold only the press-scheduled partial areas 80A and 80B. .

  By the way, as a modified example of the structure of the heating plates 70 and 72, the heating plates 70 and 72 are made of metal, and the method is performed by doping impurities only to the convex portions 76A, 76B, 76C, 78A, and 78B. In terms of resistivity, only the convex portions 76A, 76B, 76C, 78A, 78B may be sufficiently higher than the main body portions of the heating plates 70, 72. In addition, the planar shape of the heating plates 70 and 72 may be formed in a rectangular shape (the main body portion of the heating plates 70 and 72 is a rectangular parallelepiped). When such a structure is adopted, the portion through which the current can flow in the heating plates 70 and 72 is substantially limited to the main body portion of a rectangular parallelepiped, and thus the heating plates 70 and 72 are heated by a method of electric heating or induction heating. Even in this case, it becomes easy to heat the entire region of the heating plates 70 and 72 at a uniform temperature.

  In the heating apparatus according to the second embodiment described above, the workpiece 74 may be a small individual plate piece cut out from a large base plate, such as the workpiece 14 shown in FIG. Alternatively, it may be a wide plate material such as the mother plate material itself (for example, a long strip-shaped mother plate material that is a material to be processed in a progressive manner). Since only a desired partial region of the workpiece 74 can be selectively heated, the use of this heating device opens up the possibility of a new processing method such as the following. That is, materials that are difficult to be cold-pressed, such as high strength steel, are generally formed by a warm / hot press method. However, if this heating device is incorporated immediately before the molding press machine in a cold press forming line using a progressive processing method, only a specific partial region of a long strip-shaped base material that is a workpiece is selectively heated. Thus, only the specific partial area can be selectively processed by a molding press machine. As a result, cold progressive processing can be applied to materials that are difficult to cold form, such as high strength steel, instead of warm / hot press forming. In addition, in the warm / hot press forming line, by incorporating this heating device, local embossing, local punching, or local drawing can be performed more easily.

  FIG. 7 shows the structure of a heating plate used in the heating apparatus according to the third embodiment of the present invention (only one heating plate is shown representatively, but the other heating plate is the same). 7A is a cross-sectional view of the heating plate, and FIG. 7B is a plan view of the heating plate.

  Similarly to the second embodiment described above, the heating device according to the third embodiment is for selectively heating only a specific partial region of the workpiece, and the overall configuration is as follows. This is the same as that of the second embodiment shown in FIG.

  As shown in FIG. 7, convex portions 102 </ b> A and 120 </ b> B are attached to the main surface of the heating plate 100 so as to be in contact with only a specific partial region of the workpiece to be heated. These convex portions 102 </ b> A and 120 </ b> B are prepared in advance as individual components separated from the heating plate 100, and are attached to the main surface of the heating plate 100. If the production line and work material are different, the position, shape, and size of the specific partial region to be heated of the work material are different, but the same heating plate 100 is prepared by preparing the convex portions 102A and 120B according to the respective requirements. Can be used to heat different production lines and workpieces.

  In the example of FIG. 7, as a method of the heating plate 100, a heating method using the heating wire heater 104 is employed in order to heat the entire region of the heating plate 100 at a uniform temperature. However, if the material of the heating plate 100 is a metal, the shape thereof is a rectangular parallelepiped, and the protrusions 102A and 120B are made of a metal, a semiconductor, or an insulator having a sufficiently higher electrical resistivity than the heating plate 100, current heating or Even when the heating plates 70 and 72 are heated by the induction heating method, it becomes easy to heat the entire region of the heating plate 100 at a uniform temperature.

  FIG. 8 shows the overall configuration of a heating apparatus according to the fourth embodiment of the present invention. In FIG. 8, elements that are substantially the same in function as those shown in FIGS. 2 and 6 are denoted by the same reference numerals as those in FIGS. 2 and 6, and redundant description is omitted.

  The heating device shown in FIG. 8 is also for selectively heating a specific partial region of the workpiece 74 as in the second embodiment described above. And a rectangular parallelepiped metal plate similar to that of the first embodiment shown in FIG. Although several methods already demonstrated can be employ | adopted for the heating method of the heating plates 10 and 12, this embodiment employs energization heating as in the first embodiment. As in the case of the first embodiment shown in FIGS. 1 and 2, the heating current supplied from the power supply circuit 60 is caused to flow to the heating plates 10 and 12 on both side surfaces of the heating plates 10 and 12. Electrodes 20A, 20B, 22A, and 22B are joined (the specific shapes of the electrodes 20A, 20B, 22A, and 22B shown in FIG. 8 are slightly different from those shown in FIGS. 1 and 2, but the actual functions are the same). .)

  In addition, upper contact plate pieces 110 </ b> A and 110 </ b> B are disposed in front of the main surface of the upper heating plate 10 so as to come into contact with the upper surface of the region to be pressed of the workpiece 74. The upper contact plate pieces 110A and 110B are supported by slide holders 111A and 111B that are movable up and down along the columns 46A and 46B. Telescopic spacers 114A and 114B are provided between the slide holders 111A and 111B and the electrodes 20A and 20B of the upper heating plate 10. The spacers 114A and 114B are, for example, coiled springs that are fitted to the columns 46A and 46B. The spacers 114A and 114B are arranged such that the upper heating plate 10 and the upper contact plate pieces 110A and 110B are slightly separated from each other unless an external force is applied.

  Similarly, lower contact plate pieces 112 </ b> A and 112 </ b> B are disposed on the front surface of the main surface of the lower heating plate 12 so as to come into contact with the lower surface of the press work scheduled region of the workpiece 74. The lower contact plate pieces 112A and 112B are supported by slide holders 116A and 116B that are movable up and down along the columns 46A and 46B. Telescopic spacers 118A and 118B are provided between the slide holders 118A and 118B and the electrodes 22A and 22B of the lower heating plate 12. The spacers 118 </ b> A and 118 </ b> B are, for example, coiled springs that are fitted to the columns 46 </ b> A and 46 </ b> B. The spacers 118A and 118B are arranged such that the lower heating plate 12 and the lower contact plate pieces 112A and 112B are slightly separated from each other unless an external force is applied.

  The workpiece 74 is gripped by the fingers 94A and 94B of the transport bars 92A and 92B, and inserted between the upper contact plate pieces 110A and 110B and the lower contact plate pieces 112A and 112B, so that the lower contact plate pieces 112A, 112B is lowered.

  The operation of one cycle of the heating process by this heating device is basically the same as the operation already described with reference to FIG. That is, first, the heating plates 10 and 12 are heated to a predetermined heating temperature (FIG. 3, S1-S2). Since the heating plates 10 and 12 are rectangular parallelepipeds, the heating plates 10 and 12 are generally heated to a substantially uniform temperature even by the method of current heating or induction heating. Subsequently, the workpiece 74 is immediately inserted between the upper contact plate pieces 110A and 110B and the lower contact plate pieces 112A and 112B, and lowered onto the lower contact plate pieces 112A and 112B (S3). When the workpiece 74 is lowered, the lower contact plate pieces 112 </ b> A and 112 </ b> B are pushed down and are brought into close contact with the lower heating plate 12, and are also brought into close contact with the planned processing partial area of the workpiece 74. Immediately thereafter, the slide 44 is lowered, and the upper heating plate 10 is lowered (S4). When the upper heating plate 10 is lowered, the upper contact plate pieces 110A and 110B are also pushed down. Finally, the upper contact plate pieces 110A and 110B are in close contact with the planned processing partial area of the workpiece 74, and the upper heating plate 10 Also stick to. As a result, both heating plates 10 and 12 sandwich the workpiece 74.

  When the heating plates 10 and 12 sandwich the workpiece 74, only the contact plate pieces 110 </ b> A, 110 </ b> B, 112 </ b> A, and 112 </ b> B on the main surface of the heating plates 10 and 12 are in close contact with the press processing scheduled partial region of the workpiece 74. It will be. As a result, the heat of the heating plates 10 and 12 is supplied to the press work partial area of the workpiece 74 through the contact plate pieces 110A, 110B, 112A and 112B, and only the press work partial area is selectively heated. .

  In this heating device, while the heating plates 10 and 12 are energized, the contact plate pieces 110A, 110B, 112A, and 112B are separated from the heating plates 10 and 12, so that the heat conduction is performed as the contact plate pieces 110A, 110B, 112A, and 112B. A high-rate metal can be used.

  FIG. 9 shows an overall configuration of a modification of the heating apparatus according to the first embodiment shown in FIG. 9, elements having substantially the same functions as those shown in FIG. 2 are denoted by the same reference numerals. Hereinafter, the heating device of FIG. 9 will be described focusing on differences from the heating device of FIG.

  As shown in FIG. 9, the lower heating plate 12 can move in the vertical direction along columns 46 </ b> A and 46 </ b> B fixed to the base 42. Between the lower heating plate 12 and the heat insulating / insulating plate 52, members that push the lower heating plate 12 upward and separate from the heat insulating / insulating plate 52, for example, coiled springs 48A and 48B, are disposed. These springs 48A and 48B are fitted to the columns 46A and 46B. Stoppers 50A and 50B are attached to the upper ends of the columns 46A and 46B. These stoppers 50A and 50B prevent the lower heating plate 12 from further rising, and prevent the lower heating plate 12 from falling off the columns 46A and 46B.

  A heat insulating / insulating plate 54 is attached to the lower surface of the slide 44. On the lower surface of the slide 44, a guide member for controlling the position of the upper heating plate 10, for example, two support columns 53A and 53B made of an insulating material are erected vertically downward. The upper heating plate 10 can move in the vertical direction along the columns 53A and 53B. Between the upper heating plate 10 and the heat insulating / insulating plate 54, a member that pushes the upper heating plate 10 downward and separates it from the heat insulating / insulating plate 54, for example, coiled springs 52A and 52B is disposed. These springs 52A and 52B are fitted to the columns 53A and 53B. Stoppers 51A and 51B are attached to the upper ends of the columns 53A and 53B. These stoppers 51A and 51B stop further processing of the upper heating plate 10 and prevent the upper heating plate 10 from falling off the columns 53A and 53B.

  As shown in FIG. 9, when the slide 44 is located at the top dead center, the upper heating plate 10 is separated from the heat insulating / insulating plate 54 attached to the slide 44 by the action of the springs 52A and 52B. The plate 12 is separated from the heat insulating / insulating plate 52 attached to the base 42 by the action of the springs 48A and 48B. Due to this separated state, the heat insulating effect of the upper and lower heating plates 10 and 12 is good. Between the upper heating plate 10 and the lower heating plate 12, there is a sufficiently large space for taking the workpiece 14 in and out.

  As the slide 44 descends, the upper heating plate 10 and the lower heating plate 12 come into contact with both surfaces of the entire region of the workpiece 14. When the slide 44 is further lowered, the upper heating plate 10 comes into close contact with the heat insulating / insulating plate 54, and the lower heating plate 12 comes into close contact with the heat insulating / insulating plate 52. And the up-and-down heating plates 10 and 12 are pressed by the press machine 40 on both surfaces of the whole area | region of the workpiece 14 with a predetermined pressure. Thereafter, when the slide 44 is raised, the upper heating plate 10 is separated from the heat insulating / insulating plate 54 by the action of the springs 52A, 52B, and at the same time, the lower heating plate 12 is moved from the heat insulating / insulating board 52 by the action of the springs 48A, 48B. Leave.

  FIG. 10 shows an operation flow of one cycle of the heating process of the workpiece 14 performed by this heating apparatus.

  As shown in FIG. 10, in step S11, the slide 44 stands by at the top dead center. In step S12, a large current is supplied to each of the upper heating plate 10 and the lower heating plate 12, and the heating plates 10 and 12 are heated to a predetermined heating temperature. The heating temperature of the heating plates 10 and 12 is determined in advance according to the expected heating temperature of the workpiece 14. The heating plates 10 and 12 are heated to the heating temperature almost uniformly as a whole in a very short time on the order of seconds.

  As soon as the heating plates 10 and 12 are heated to the above heating temperature, the plate-like workpiece 14 before pre-molding is placed on the lower heating plate 12 in step S13. Immediately thereafter, in step S14, the slide 44 is lowered to push down the upper heating plate 10, and the workpiece 14 is sandwiched between the two heating plates 10 and 12. Subsequently, in step S15, the state in which the workpiece 14 is sandwiched between the two heating plates 10 and 12 is maintained for a predetermined heating time. In the meantime, a slight pressing force that does not deform the workpiece 14 is applied to the upper heating plate 10, and the main surfaces of both the heating plates 10 and 12 are brought into close contact with both surfaces of the entire area of the workpiece 14. The workpiece 14 is heated as a whole, and oxidation of both sides of the workpiece 14 is also prevented.

  After maintaining the sandwich state for a predetermined time, the slide 44 moves up in step S16. Subsequently, immediately in step S17, the heated workpiece 14 is taken out from the lower heating plate 10, and the workpiece 14 is immediately set in a press machine (not shown) for press molding. Thereafter, in a press machine for press molding, press molding of the workpiece 14 at a heating temperature is performed.

  FIG. 11 is a front view showing an overall configuration of a modified example of the heating apparatus according to the second embodiment of the present invention shown in FIG. 6. In FIG. 11, elements that are substantially functionally similar to those shown in FIG. 6 are given the same reference numerals as in FIG. 6. In FIG. 11, a power supply device and wiring for supplying a heating current to the heating plates 70 and 72 are not shown. Hereinafter, the heating device of FIG. 11 will be described focusing on differences from the heating device of FIG.

  As shown in FIG. 11, a heat insulating / insulating plate 52 is laid on the upper surface of the base 42. Further, support posts 46A and 46B are erected vertically above the upper surface of the base 42. The lower heating plate 72 can move in the vertical direction along the columns 46A and 46B. Heat insulating / insulating plates 73A and 73B are also provided on both side surfaces of the lower heating plate 12. Members for pushing up the lower heating plate 72 and separating it from the heat insulating / insulating plate 52 on the base 42, for example, coiled springs 48A and 48B, are fitted into the columns 46A and 46B. The stoppers 50A and 50B prevent the lower heating plate 72 from falling off the columns 46A and 46B.

  A heat insulating / insulating plate 54 is attached to the lower surface of the slide 44. On the lower surface of the slide 44, struts 53A and 53B are erected vertically downward. The upper heating plate 70 can move in the vertical direction along the columns 53A and 53B. The heat insulating / insulating plates 91A and 91B are also provided on both side surfaces of the upper heating plate 70. Members for pushing down the upper heating plate 70 to be separated from the heat insulating / insulating plate 54 on the slide 44, for example, coiled springs 52A and 52B, are fitted to the columns 53A and 53B. The stoppers 51A and 51B prevent the upper heating plate 70 from falling off from the columns 53A and 53B.

  Also in the heating device according to this modification, when the slide 44 is at a high position, the upper heating plate 70 is separated from the heat insulating / insulating plate 54 on the slide 44, similarly to the heating device according to the modification shown in FIG. Since the lower heating plate 72 is separated from the heat insulating / insulating plate 52 on the base 42, the heat insulating effect of the upper and lower heating plates 70, 72 is good. When the slide 44 is lowered, the upper and lower heating plates 70 and 72 are pressed against the workpiece 74.

  FIG. 12 is a front view showing an overall configuration of a modification of the heating apparatus according to the third embodiment of the present invention shown in FIG. In FIG. 12, elements substantially similar to the elements shown in FIG. 8 are denoted by the same reference numerals as those in FIG. Hereinafter, the heating device of FIG. 12 will be described focusing on differences from the heating device of FIG.

  As shown in FIG. 12, a heat insulating / insulating plate 52 is laid on the upper surface of the base 42. Further, support posts 46A and 46B are erected vertically above the upper surface of the base 42. The lower heating plate 12 can move in the vertical direction along the columns 46A and 46B. Members for pushing up the lower heating plate 72 and separating it from the heat insulating / insulating plate 52 on the base 42, for example, coiled springs 48A and 48B, are fitted into the columns 46A and 46B. Further, the lower contact plate pieces 112A and 112B can move up and down along the columns 46A and 46B. Members for pushing up the lower contact plate pieces 112A and 112B and separating them from the lower heating plate 12, for example, coiled springs 118A and 118B, are fitted to the columns 46A and 46B. The stoppers 50A and 50B prevent the lower heating plate 12 and the lower contact plate pieces 112A and 112B from falling off from the columns 46A and 46B.

  A heat insulating / insulating plate 54 is attached to the lower surface of the slide 44. On the lower surface of the slide 44, struts 53A and 53B are erected vertically downward. The upper heating plate 10 can move in the vertical direction along the columns 53A and 53B. Members for pushing down the upper heating plate 10 and separating it from the heat insulating / insulating plate 54 on the slide 44, for example, coiled springs 52A and 52B, are fitted to the support columns 53A and 53B. Further, the upper contact plate pieces 110A and 110B can move up and down along the columns 53A and 53B. Members for pushing down the upper contact plate pieces 110A, 110B and separating them from the upper heating plate 10, for example, coiled springs 114A, 114B, are fitted to the columns 53A, 53B. The stoppers 51A and 51B prevent the upper heating plate 70 and the upper contact plate pieces 110A and 110B from falling off from the columns 53A and 53B.

  Also in the heating device according to this modification, when the slide 44 is at a high position, the upper heating plate 10 is the heat insulating / insulating plate on the slide 44 as in the heating devices according to the modifications shown in FIGS. Since the lower heating plate 12 is away from the heat insulating / insulating plate 52 on the base 42, the heat insulating effect of the upper and lower heating plates 10, 12 is good. When the slide 44 is lowered, the upper and lower heating plates 10 and 12 are pressed against the upper contact plate pieces 110A and 110B and the lower contact plate pieces 112A and 112B, respectively, and the upper contact plate pieces 110A and 110B and the lower contact plate pieces 112A and 112B. Is pressed against the workpiece 74.

  As mentioned above, although embodiment of this invention was described, this embodiment is only the illustration for description of this invention, and is not the meaning which limits the scope of the present invention only to this embodiment. The present invention can be implemented in various other modes without departing from the gist thereof.

  For example, a method such as hanging can be employed as a method of holding the upper heating plate 10 in order to eliminate a support that interferes with the conveyance of the workpiece. In addition, the area of the heating plate that is heated to a substantially uniform temperature does not necessarily have to be the entire area of the heating plate, and is a partial area if at least the area that acts on the workpiece is covered. May be.

1 is a perspective view showing a configuration of a main part of a heating apparatus for a workpiece for press molding according to a first embodiment of the present invention. 1 is a front view showing the overall configuration of a heating device according to a first embodiment. The flowchart which shows the flow of operation | movement of 1 cycle of the heating process of the workpiece performed by the heating apparatus concerning 1st Embodiment. FIG. 4A shows the structure of two heating plates used in the heating device according to the second embodiment of the present invention. In particular, FIG. 4A is a sectional view showing the arrangement relationship of the two heating plates, and FIG. The top view of a heating plate. Sectional drawing which shows the press molding result example of the workpiece after heating with the heating apparatus concerning 2nd Embodiment. The front view which shows the whole structure of the heating apparatus concerning 2nd Embodiment. The structure of the heating plate used with the heating apparatus concerning the 3rd Embodiment of this invention is shown, Especially FIG. 7 (A) is sectional drawing of a heating plate, FIG.7 (B) is a top view of a heating plate. The front view which shows the whole structure of the heating apparatus concerning the 4th Embodiment of this invention. FIG. 6 is a front view showing an overall configuration of a heating device according to a modification of the first embodiment. The flowchart which shows the flow of operation | movement of 1 cycle of the heating process of the workpiece performed by the heating apparatus concerning the modification of 1st Embodiment. The front view which shows the whole structure of the heating apparatus concerning the modification of 2nd Embodiment. The front view which shows the whole structure of the heating apparatus concerning the modification of 4th Embodiment.

Explanation of symbols

10, 70, 100 Upper heating plate 12, 72, 100 Lower heating plate 14, 74 Work material 20A, 20B, 22A, 22B Electrode 40 Press machine for heating device 42 Base 44 Slide 52, 54 Insulation / insulation plate 60 Power supply Circuit 76A, 76B, 76C, 78A, 78B, 102A, 102B, Heat plate convex part 80A, 80B Processed partial area of work material 84, 104 Heating wire heater 110A, 110B Upper contact plate piece 112A, 112B Lower contact plate Fragment

Claims (5)

In a heating device that is installed in-line in a press machine and heats a plate-shaped workpiece before press molding,
It is arranged between the upper surface of the base of the press machine and the lower surface of the slide so that the workpiece can be inserted between them, and one moves closer to or away from the other as the slide moves. Two heating plates that can be moved;
Heating means for heating each of the heating plates to a substantially uniform temperature over at least a region acting on the workpiece;
Control means (66) for controlling the heating means,
Each of the heating plates is a plate having a rectangular planar shape,
The heating means is an energizing heating means for passing an electric current to the heating plate itself, or an induction heating means for applying an induction electric field to the heating plate itself,
When the heating plate is heated and the workpiece is inserted between the heating plates, the workpiece is arranged such that one of the heating plates approaches the other and comes into close contact with both surfaces of the predetermined region of the workpiece. Sandwich and
And the heating apparatus which heats the said workpiece | work by maintaining the state which the said heating plate sandwiched the said workpiece | work with the applied pressure of the grade which does not deform | transform the said workpiece . The heating device according to claim 1, wherein
A heating device in which the predetermined region of the workpiece (14) is the entire region of the workpiece (14). The heating device according to claim 1, wherein
The heating device, wherein the predetermined region of the workpiece (74) is a partial region of the workpiece (74).   The heating device according to claim 1, wherein
  The energization heating means is a heating device that is an electrode provided on each of opposite side surfaces of each heating plate having a rectangular planar shape.   The heating device according to claim 1, wherein
  Insulating plates (52, 54) are provided between the base and one heating plate of the two heating plates, and between the slide and the other heating plate of the two heating plates, respectively.
  When the two heating plates are in the most distant state, the heating plate is heated in a state where each heating plate and each heat insulating plate are separated from each other,
  A heating device in which each heating plate and each heat insulating plate are in close contact with each other when the heating plate is sandwiched between the workpieces.

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