JP2013131333A - Electric heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for suppressing uneven heating of a material after heating, by limiting the amount of heat removal by means of an electrode for energization and an electrode holder which holds the material in conjunction with the electrode.SOLUTION: In the electric heating apparatus, a material is held by means of a pair of electrodes and a pair of electrode holders, and heated by energizing between the electrodes. At least a part touching the material of at least one of the electrode and the electrode holder consists of a member having thermal insulation. In a preferable electric heating apparatus, the electrode holder is provided with an energization confirmation means for confirming energization from the electrode to the material.

Description

  The present invention relates to an electric heating apparatus that heats a material to a predetermined temperature or higher by electric heating.

  Conventionally, in the field of hot stamping, energization heating has been widely used in order to heat a material to a quenching temperature or higher (for example, Patent Document 1). Patent Document 1 discloses a configuration in which a work is energized using an electrode that moves close to the work placed on a mold.

JP 2008-87001 A

A general energization heating apparatus energizes in the state which clamped a material with an electrode and an electrode presser arranged so as to oppose the electrode and material. These electrodes and electrode holders are made of a highly conductive material such as chrome copper, and their own heating due to Joule heat is suppressed. For this reason, by conducting energization heating, a large temperature difference occurs between the material heated by Joule heat and the unheated electrode and electrode holder, and the amount of heat removed from the material to the electrode and electrode holder increases. Includes challenges.
As described above, in the conventional electric heating apparatus, heat removal due to the temperature difference between the electrode and the electrode holder during the electric heating and the material to be heated is not considered, and the temperature in the vicinity of the clamped portion of the material is low. Uneven heating may occur. Therefore, the present invention provides a technique for suppressing the amount of heat removed by an electrode for energization and an electrode presser that clamps the material together with the electrode, and suppressing the occurrence of temperature unevenness in the heated material.

  The energization heating apparatus of the present invention is an energization heating apparatus that heats the material by sandwiching the material with at least a pair of electrodes and a pair of electrode presses and energizing between the electrodes, and includes at least the electrode and the electrode presser On the other hand, at least a part in contact with the material is constituted by a member having heat insulation.

  In a preferred embodiment of the energization heating device, the electrode holder is provided with an energization confirmation means for confirming energization from the electrode to the material.

  According to the present invention, it is possible to reduce heat removal due to a temperature difference between the electrode and the electrode holder and the material, and to reduce temperature unevenness after energization heating.

It is a figure which shows an electricity heating apparatus. It is a figure which shows the mode of the electricity supply confirmation in an electricity heating apparatus. It is a figure which shows another embodiment of an electric heating apparatus. It is a figure which shows other embodiment of an electric heating apparatus.

As shown in FIG. 1, the energization heating apparatus 1 includes a pair of electrodes 10 and 10 that are in contact with the clamped portions 3 and 3 at both ends of the material 2 and energized, and the electrode 10 is covered with the material 2. A pair of electrode holders 20 and 20 facing each other with the clamp part 3 interposed therebetween are provided.
The material 2 is a metal rectangular plate material that can be quenched, such as a steel plate, and is heated by the energization heating device 1 to a temperature equal to or higher than the quenching temperature. Then, it is press-molded with a hot stamping die and quenched by being cooled.

  As shown in FIG. 1, the electrode 10 includes an energizing part 11 and a reinforcing part 12. The electrodes 10 and 10 are arranged at both ends in the longitudinal direction or the short direction of the material 2 formed in a rectangular shape, and contact the material 2 from below. The electrodes 10 and 10 are configured to have a width equal to or greater than the width of the clamped portion of the material 2 at the contact portion with the material 2.

The energizing portion 11 is made of a highly conductive material such as chrome copper. The energizing portions 11 and 11 of the paired electrodes 10 and 10 are connected to the positive electrode and the negative electrode of an appropriate power supply device, and a voltage is applied between the energizing portions 11 and 11 to apply a current.
The reinforcing portion 12 is a heat insulating member made of a material having heat insulating properties, and is a reinforcing member that is disposed in contact with the side portion of the energizing portion 11 and reinforces its strength. The reinforcing portion 12 is disposed on the inner side in the energizing direction with respect to the energizing portion 11. The heat insulating material constituting the reinforcing portion 12 may be any material as long as the material 2 can secure the strength enough to clamp the material 2 and the heat resistance against the temperature of the material 2 to be heated.

  By configuring a part of the contact portion of the electrode 10 with the material 2 with the reinforcing portion 12 made of a heat insulating member, the reinforcing portion can be used even when the energization by the energizing portion 11 is performed and the temperature of the material 2 rises. 12, it is possible to suppress the movement of heat caused by the temperature difference between the material 2 and the electrode 10.

From the viewpoint of reducing the amount of heat removed by the electrode 10, it is preferable that the thickness of the energizing portion 11 in the energizing direction, that is, the area of the contact portion between the energizing portion 11 and the material 2 is as small as possible. By reinforcing the energizing part 11 with 12, the width of the energizing part 11 can be made as small as possible. Thereby, the amount of heat extracted from the heated material 2 to the energizing portion 11 can be reduced as much as possible without reducing the strength of the electrode 10 itself.
Moreover, by arrange | positioning the reinforcement part 12 inside the electricity supply area | region by the electricity supply part 11, the to-be-heated area | region of the raw material 2 can fully be ensured, and it can contribute to a yield improvement.

As shown in FIG. 1, the electrode holder 20 contacts the material 2 from above. The electrode holder 20 can be moved up and down with respect to the electrode 10. By moving the electrode holders 20 and 20 toward the material 2 while the material 2 is placed on the electrodes 10 and 10, the electrode 10. 10 and the electrode holders 20 and 20 hold the clamped portions 3 and 3 of the material 2 from above and below.
The electrode holder 20 is a heat insulating member made of a heat insulating material. The heat insulating material constituting the electrode holder 20 may be any material as long as it can secure the strength enough to clamp the material 2 and the heat resistance against the temperature of the material 2 to be heated.
The electrode holder 20 has the same shape as the material contact surface of the electrode 10. That is, the thickness of the electrode presser 20 in the energizing direction is set to be equal to the total thickness of the energizing part 11 and the reinforcing part 12.

As described above, in the energization heating device 1 of the present embodiment, the pair of electrodes 10 and 10, part of which is made of a heat insulating member, and the pair of electrode holders 20 and 2 made of a heat insulating member. In a state where the material 2 is sandwiched, the material 2 is energized to generate Joule heat to heat the material 2.
In this way, by configuring the reinforcing portions 12 and 12 of the electrodes 10 and 10 and the electrode holders 20 and 20 with heat insulating members, heat removal due to a temperature difference from the heated material 2 can be suppressed. Further, uneven heating temperature in the vicinity of the clamped portion 3 of the material 2 can be reduced.

  In addition, although almost all of the electrode holder 20 is configured by a heat insulating member, only the contact portion with the material 2 may be configured as a separate member by a heat insulating member, or a part of the contact portion with the material 2 may be formed. You may comprise as a heat insulation member. In any case, heat removal from the material 2 can be suppressed by disposing a heat insulating member on the contact surface with the material 2.

As shown in FIG. 2, a conductive portion 30 for confirming energization is provided on one of the electrode holders 20, 20.
The conductive part 30 is connected to the electrode part 31 exposed on the lower surface of the electrode holder 20, that is, the contact surface with the material 2, the conductor 32 extended from the electrode part 31 to the outside of the electrode holder 20, and the conductor 32. Current detector 33.

When a current is applied between the current-carrying parts 11 and 11 of the electrodes 10 and 10, a current flows from the current-carrying part 11 to the electrode part 31 through the material 2. Then, a current flows through the current detection unit 33 through the electrode unit 31 and the conductive wire 32 and is detected, and energization is confirmed.
On the other hand, when the clamping by the electrode 10 and the electrode holder 20 is insufficient, or when the contact between the current-carrying portion 11 of the electrode 10 and the material 2 is insufficient, the current is detected by the current detection unit 33. It is not detected, and it is determined that there is an energization failure.

Note that the contact failure between the current-carrying portion 11 of the electrode 10 and the material 2 is not limited to the conductive portion 30 as described above, but a pressure sensor that detects the pressure caused by the clamping of the material 2 by the electrode 10 and the electrode presser 20 is used. Can be detected. That is, the pressure generated between the electrode 10 and the electrode holder 20 is detected by providing a pressure sensor on the electrode holder 20 that moves and presses against the electrode 10. As described above, the means for confirming the energization between the electrodes 10 and 10 (between the energization portions 11 and 11) is not limited to detecting the current, but the contact between the electrode 10 and the material 2 during energization is determined as good / bad. Energization can also be confirmed by detecting.
For example, it is possible to detect a clamping failure, that is, an energization failure, by setting a clamping pressure by the electrode 10 and the electrode holder 20 in advance and detecting the actual clamping pressure by the pressure sensor during energization.

As shown in FIG. 3, as another embodiment of the energization heating device 1, the electrode 10 is configured by the energizing portion 11 and the reinforcing portion 12, so that a heat insulating member is provided on a part of the electrode side, and the electrode holding side It is also possible to use the electrode holder 40 having the same configuration as that of the prior art. The electrode holder 40 is a rigid body made of the same material as the electrode, such as chromium copper.
Also in this case, the amount of heat removed from the heated material 2 to the electrode 10 side can be reduced, and uneven heating temperature in the vicinity of the clamped portion 3 of the material 2 can be reduced.

As shown in FIG. 4, as another embodiment of the electric heating device 1, the electrode retainer 20 is formed of a heat insulating member, thereby providing a heat insulating member on the electrode retainer side, and the electrode side is similar to the conventional one. It is also possible to use the electrode 50 having the configuration. The electrode 50 is made of a highly conductive material such as chromium copper as a whole.
Also in this case, the amount of heat removed from the heated material 2 to the electrode presser 20 side can be reduced, and uneven heating temperature in the vicinity of the clamped portion of the material 2 can be reduced.

In the above-described embodiment, a case where current heating is performed using “a pair of electrodes and a pair of electrode holders” is described, but the present invention uses “two pairs of electrodes and two pairs of electrode holders”. The present invention can also be applied to the case where the electric heating is performed, and the electrodes and the electrode pressers are not limited to a pair. Thus, when applying a combination of a plurality of pairs of electrodes or electrode holders, for example, the clamped portion of the material can be arranged in a state of being divided in the width direction (direction perpendicular to the energization direction).
Further, the number of pairs of electrodes and electrode holders is not limited to the same number. For example, current heating may be performed using two pairs of electrodes and a pair of electrode holders.

  1: current heating device, 2: material, 10: electrode, 20: electrode holder, 30: conductive part (energization confirmation means)

Claims (2)

An energization heating apparatus that heats the material by sandwiching the material with at least a pair of electrodes and a pair of electrode presses and energizing between the electrodes,
At least one of the electrode and electrode retainer, which is in contact with the material, is constituted by a member having a heat insulating property.   The energization heating apparatus according to claim 1, wherein the electrode holder is provided with energization confirmation means for confirming energization from the electrode to the material.

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