JPH0734919Y2 - Direct current heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a heating device for directly energizing a steel pipe.

(Prior Art) For example, in a U-bend steel pipe used for a heat exchanger or the like, it is customary to heat-treat this portion in order to remove the residual stress in the bend portion subjected to the bending process. It is processed by the direct current method. In other words, this heat treatment technique is a method in which the material to be treated is sandwiched and held by the electrodes, an electric current is passed through the material itself, and the Joule heat generated at that time is used, and Fig. 5 shows a conventional apparatus. ing.

In this device, an electrode for clamping a material A to be processed is divided into a lower electrode 1 and an upper electrode 2 each having a concave groove suitable for clamping the material A formed oppositely, and a fixed lower side. The upper electrode 2 is moved up and down by the cylinder 3 with respect to the electrode 1 to perform the clamping and releasing operation of the material A.
Power is supplied from the lower electrode 1 to the upper electrode 2
Power is supplied through the rod 4 which also serves as a lifting guide.

(Problems to be solved by the invention) By the way, in the conventional direct-current heating device as shown in FIG. 5, since there is a power feeding rod which also serves as a guide for the upper electrode, the material can be carried in from the front. It is limited to one direction and not only requires a wide loading space, but also has a problem in automating material loading and unloading. In addition, since the rod also serves as a lifting guide for the upper electrode, the contact resistance changes due to wear of the sliding part, and sometimes the current supplied to the upper and lower parts of the material is not balanced and an excessive current is supplied. There was a problem that a heat mark was generated in.

It should be noted that it is possible to conduct electricity by removing the rod and supplying power from the lower electrode, but in this case, since the current supplied to the lower part of the material is doubled, the contact resistance between the electrode and the material causes
There is a problem that the material is extremely heated and a heat mark is generated.

The present invention has been made to solve the above problems, and an object thereof is to provide a device in which the current densities of the upper and lower electrodes are made uniform during energization and the material loading / unloading can be easily automated. There is.

(Means for Solving the Problems) In order to achieve the above object, in the direct current heating device of the present invention, a device provided with upper and lower split electrodes in which an upper electrode moves up and down with respect to a lower electrode which is a fixed side. Therefore, blade-type switch-type contactors whose contact pressure can be adjusted are provided on both sides of the upper and lower electrodes so that they are in close contact with each other when the material is clamped.

(Operation) In the direct current heating device configured as described above,
The material can be carried into the equipment from the side and the contact pressure can be adjusted by the contactor to reduce the contact resistance and divert the current to the upper and lower electrodes to make the current density uniform and reduce the current to the lower electrode. Concentration and extreme heating of the material due to heat generation in the contact area is prevented.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

Reference numeral 1 is a lower electrode which is a fixed side, and 2 is an upper electrode which opposes the lower electrode 1, which is moved up and down by a cylinder 3 attached via an insulating member 13. Further, contact grooves 5 are provided on the facing surfaces of the electrodes 1 and 2 so as to maintain a necessary appropriate contact area and contact pressure with the material A and reduce contact resistance. Material A is clamped between 5. A current-carrying member 6 is connected to the lower electrode 1.

Reference numeral 7 is a blade-type switch-type contactor that is dividedly arranged on both sides of the electrodes 1 and 2, and a female member 8 attached to the lower electrode 1
And a male member 9 attached to the upper electrode 2, and the female member 8 is divided into a fixed side 10 and a movable side 11, and the contact pressure on the male member 9 is determined by the cylinder 3. A mechanism incorporating a spring 12 is adopted so that the pressing force of the electrode 2, that is, the contact pressure between the material and the electrode can be adjusted without disturbing. A pressing mechanism using a cylinder instead of the spring may be applied. The contactor 7 may be made of, for example, chromium copper having a high electric conductivity, and silver cadmium oxide having a good contact efficiency, which is welded to the contactor 7, and the length in the longitudinal direction is allowed. It has been decided as big as possible.

That is, comparing the resistivity of the material 4 with the electrodes 1 and 2, the material >>
Due to the relationship of the electrodes, the current flowing from the electrodes to the material does not flow uniformly over the entire contact portion, and as shown in FIG. 4, it increases as the resistance value c approaches a lower resistance value a.

Therefore, the contact resistance of the contactor 7 must be minimized in order to divert the current from the contactor 7 to b → d for the purpose of reducing the current density at the portion a. Is met by the considerations described in.

In the embodiment shown in the figure, a heating device for a U-bend steel pipe is shown, but it can be applied as a heating device for a straight pipe by arranging them in series.

By the way, the material A is carried from the side of the apparatus by a carry-in apparatus (not shown) as shown in FIG. 1, and first set on the lower electrode 1. Then, the upper electrode 2 is lowered and clamped, but at the same time, the contactor 7 is in contact with the upper electrode 2 and the current is shunted to the upper and lower electrodes as shown in FIG. Get rid of.

(Effects of the Invention) Since the present invention is configured as described above, it has the following effects.

That is, by providing a blade-type switch-type contactor capable of adjusting contact pressure on the side of the upper and lower electrodes, the upper electrode power feeding rod is not required as in the conventional case, and therefore, the material carry-in direction can be freely selected. , Its automation becomes easy.

Also, by providing a contactor with adjustable contact pressure and setting the contact resistance to be small, the current is shunted from both sides of the material to the upper and lower electrodes, and the density is made uniform, so the lower electrode The current is concentrated on the material and the extreme heating of the material due to heat generation at the contact portion between the electrode and the material is prevented, and uniform heat treatment is achieved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a side view, and FIG. 3 is a front view showing a relational structure between an electrode and a contactor.
FIG. 4 is an explanatory diagram showing the flow of current during heating, and FIG.
The figure is an explanatory view of a conventional device, (a) is a side view, (b)
Is a front view. 1 is a lower electrode, 2 is an upper electrode, 3 is a cylinder, 5 is a contact groove, and 7 is a blade switch contactor.

Claims (1)

[Scope of utility model registration request] 1. A device comprising upper and lower split electrodes in which an upper electrode moves up and down with respect to a lower electrode which is a fixed side, wherein both side portions of the upper and lower electrodes are in close contact with each other when a material is clamped. A direct electric heating device, which is equipped with a blade switch contactor whose pressure can be adjusted.