JPH0214132Y2 - - Google Patents

Description

[Detailed Description of the Invention] a. Field of Industrial Application The present invention relates to a clamping device for a welding machine. More specifically, the present invention relates to a clamp device that can prevent the spring of the clamp device from heating up.

b. Prior Art In a welding machine that electrically converts energy into thermal energy for welding, a clamping device is used to electrically connect the workpiece to a power source in order to supply current to the workpiece or ground the workpiece. things will be done.

FIG. 4 is a conceptual diagram of arc welding.

Two objects to be welded A and B are connected to the ground side of a power source PS by a clamp device C via a ground wire E, and are arc welded by a welding machine D connected to the high voltage side via a high voltage line H. At this time, the power source PS, high voltage line H, welding machine D, objects to be welded A and B, clamp device C, ground wire E, and power source PS form a closed circuit.

FIG. 5 is a partially sectional side view of the clamp device C of FIG. 4.

The clamping device C clamps the workpiece to contacts 1a and 2.
Two clamp bodies 3a, 4a held by a,
The clamp bodies 3a, 4a are hinged to each other at the center, and a ground wire E is fixed to one clamp body 4a. Furthermore, in order to clamp the workpiece between the contacts 1a and 2a,
A spring 5a is arranged between the clamp bodies 3a and 4a. This spring 5a is connected to the contacts 1a and 2a.
The clamp bodies 3a, 4a are always urged in the direction in which the clamp bodies 3a, 4a are closed.

When a current i ₀ flows into the clamp device from the object to be welded, it is divided at the contacts 1a and 2a, and part of the current flows through the clamp body 3a and the other part flows through the clamp body 4a. Clamp body 4 connected to ground wire E
The current i ₄ flowing into a directly reaches the ground wire E.
On the other hand, the current flowing into the other clamp body 3a
The current i ₃ is divided into a current i ₂ flowing through the hinge and a current i ₅ flowing through the spring 5a, which flow into the clamp body 4a, and further reach the power source via the ground wire E.

c. Problems to be Solved by the Invention FIG. 6 is an equivalent circuit for the current flowing through the clamp device of FIG. 5. This reduces the contact resistance between the workpiece to be welded and the clamp bodies 3 and 4, respectively.
R ₃ , R ₄ , R ₂ is the electrical resistance of the path passing through the hinge between clamp body 3a and clamp body 4a,
The electrical resistance of the path passing through the spring 5 is _R5 . Note that heat is generated by resistance and not by inductance and capacitance, so we will omit the explanation.

As is clear from FIG. 6, the amount of heat generated per unit time in the spring portion is R ₅ i ₅ ² . In other words, when i ₅ is large, the spring 5a is heated due to the heat generated in the spring 5a.
becomes hot. Generally, the spring 5a is heat-treated to improve its elastic force, but the heat generated causes the spring 5a to be annealed and the elastic force necessary for the clamping device is lost. As a result, it no longer functions as a clamping device, and the clamp must be replaced frequently.

Also, if you touch the spring without realizing it is hot, you may get burns.

The present invention aims to eliminate the above-mentioned problems of the conventional clamp devices, and provides a clamp device that does not generate heat in the spring.

d Means for solving the problem Two clamp bodies having contact portions for sandwiching the welded part and combined with each other by a hinge, and the clamp disposed between the clamp bodies so that the contact portions are closed. In a clamp device having a spring that constantly biases the body, the vicinity of the point where the spring contacts both clamp bodies is connected by a flexible bypass cord made of a good electrical conductor and having a substantially U-shape. The above problem has been solved by a clamp device characterized in that the two clamp bodies are electrically coupled.

e Effect In the clamp device according to the present invention, the clamp bodies of the clamp device are electrically short-circuited by a flexible bypass cord made of a good electrical conductor. Here, since the member that short-circuits the clamp bodies is flexible, the function as a normal clamp device is the same as that of the prior art.

However, since the spring between the clamp bodies is short-circuited by the electrically conductive member, no current flows through the spring. In other words, there is no heat generation in the spring.

f Embodiment FIG. 1 is a partially sectional side view of a preferred embodiment of the clamp device according to the present invention, and FIG.
It is a partial cross-sectional side view taken along line A.

This clamp device includes two clamp bodies 3 and 4 that clamp the workpiece at contacts 1 and 2, and the clamp bodies 3 and 4 are fixed together at the center with a hinge. A ground wire E is fixed to 4. Contacts 1, 2
A spring 5 is disposed between the clamp bodies 3 and 4 to clamp the workpiece to be welded. This spring 5 is
The clamp bodies 3 and 4 are constantly biased in the direction in which the contacts 1 and 2 close.

The clamp bodies 3 and 4 are electrically short-circuited by a flexible bypass cord 6 made of a bundle of thin copper wires. The flexible bypass cord 6 has a U-shape so as not to restrict the relative movement of the clamp bodies 3, 4.

Since the flexible bypass cord 6 is used to short-circuit the current that should flow through the spring 5, it is important that the contact resistance between its ends and the clamp bodies 3, 4 is sufficiently small.

In this embodiment, a copper wire bundle is crimped with a terminal member 7, and the terminal member 7 is fixed to the clamp bodies 3, 4 with mounting fittings 8, 9. Note that in order to reduce contact resistance, it is preferable to use welding and adhesion.

g. Effects FIG. 3 is an equivalent electric circuit of the clamp device according to the present invention. Note that the meanings of reference symbols R ₂ , R ₃ , R ₄ , and R ₅ correspond to those in FIG.

When a current i ₀ flows into the clamp device from the workpiece, the current i flowing into the clamp body 4 connected to the ground wire E flows directly to the ground wire E.
On the other hand, the current _i6 flowing into the other clamp body 3 passes through the flexible bypass cord 6, reaches the clamp body 4, and further flows to the ground wire E.

Since the flexible bypass cord is short-circuited in this way, there is no heat generation caused not only by the resistance R ₅ of the spring 5 but also by the resistance R ₂ in the hinge.

In this way, the absence of heat generation in the spring 5 means that the temperature rise of the spring 5 is small, and its elastic force does not disappear.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view of a preferred embodiment of the clamp device according to the present invention, and FIG.
3 is an equivalent electric circuit of the clamping device according to the present invention, FIG. 4 is a conceptual diagram of arc welding, and FIG. 5 is a partially sectional side view of the clamping device of FIG. FIG. 6 is an equivalent circuit of the clamping device shown in FIG. 1, 2... Contact, 3, 4... Clamp body,
5... Spring, 6... Flexible bypass cord.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A clamping device used in a welding machine that converts electrical energy into thermal energy to weld, which has a contact part that clamps the workpiece while electrically contacting it. In the clamp device, the clamp device has two clamp bodies that are combined with each other by a hinge, and a spring that is disposed between the clamp bodies and always biases the clamp bodies so that the contact portion closes. The two clamp bodies are electrically connected by a flexible bypass cord made of a good electrical conductor and having a substantially U-shape in the vicinity of the point where the two clamp bodies come into contact with each other. Welding machine clamp device. (2) The clamp device for a welding machine according to claim (1), wherein the bypass cord is a copper wire electrically connected in parallel to the clamp body. (3) The clamping device for a welding machine according to claim (1) of claim 1, wherein the welding machine is an arc welding machine.