Force-controlled resistance welding device

• US 6,204,468 B1
• Filed: 12/04/1997
• Issued: 03/20/2001
• Est. Priority Date: 12/30/1994
• Status: Expired due to Term

• Current Assignee: Regie Nationale Des Usines Renault (Renault)
• Original Assignee: Regie Nationale Des Usines Renault (Renault)
• Inventors: Habert, Patrick
• Primary Examiner(s): Shaw, Clifford C.
• Application Number:
  US08/952,827
• Time in Patent Office: 1,202 Days
• Field of Search: 219/86.51, 219/86.41, 219/86.61, 219/86.7
• US Class Current: 219/86.51
• CPC Class Codes: B23K 11/255 the measured parameter being a force B23K11/253 takes precedence
• CPC Class Codes: B23K 11/257 the measured parameter being an electrical current
• CPC Class Codes: B23K 11/311 the actuating device comprising an electric motor
• CPC Class Codes: B23K 11/318 Supporting devices for electrode holders

Abstract

Resistance welding device of the type comprising two welding electrodes (21, 31) that are displaceable in relation to one another and can clamp between them the sheet metal to be welded. One of said electrodes (31) is connected to driving means formed by a screw-nut mechanism (8, 9) operated by an electric motor (6), said driving means being connected to electronic control means (7) capable of controlling the force with which the electrodes (21, 31) clamp said sheet metal to be welded by controlling the supply current of the electric motor (6). The device of the invention is characterized in that said screw-nut mechanism transmitting the force of the motor (6) to the electrodes (21, 31) is highly efficient and reversible, and in that said electronic means (7) control the clamping force of said electrodes by a closed control loop using the value of the supply current passing through the electric motor (6).

Claims

1. Resistance welding apparatus comprising:

two welding electrodes which move in relation to one another and clasp between them the sheets to be welded,

at least one of said welding electrodes being connected to a drive means which includes a screw-nut mechanism operated by an electric motor,

said drive means being connected to an electronic command means for controlling the force with which the electrodes clasp said sheets to be welded by managing the supply current of said electric motor,

means for supplying the electrodes with current,

said screw-nut mechanism transmitting the force of the motor to the electrodes, being reversible and having a helix angle which causes said force and said supply current to have a linear relationship, and

said electronic command means controlling the clamping stress of the electrodes through a closed-looped servomechanism using a sensed value of the supply current.

2. Resistance welding apparatus according to claim 1, characterized in that the helix angle is greater than six degrees.

3. Resistance welding apparatus according to claim 2, characterized in that the helix angle is between six and ten degrees.

4. Resistance welding apparatus according to claim 3, characterized in that a microcomputer constituting said electronic command means drives the current supplying the electric motor through a current generator, which relays to it via a specific link the a sensed value of the current supplying the electric motor.

5. Resistance welding apparatus according to claim 2, characterized in that a microcomputer constituting said electronic command means drives the current supplying the electric motor through a current generator, which relays to it via a specific link a sensed value of the current supplying the electric motor.

6. Resistance welding apparatus according to claim 1, characterized in that a microcomputer constituting said electronic command means drives the current supplying the electric motor through a current generator, which relays to it via a specific link a sensed value of the current supplying the electric motor.