Spot welding machine

[0016] The present invention will be described in further detail below in conjunction with the embodiments of the drawings.

[0017] Such as Figure 1 to Figure 4 As shown, the spot welding machine of this embodiment is used to weld the inner plate a and the outer plate b of an automobile door frame column. The spot welding machine includes a vertical machine base 1, a fixed platform 11, and an upper electrode 12 and a lower electrode corresponding to each other. 13. Wherein, the fixed platform 11 is set on the machine base 1, and its middle part is opened with a through hole opposite to the lower electrode 13; the lower electrode 13 is fixed on the machine base 1 of the spot welding machine through the lower grip bar 14, and the upper end is inserted in In the through hole of the fixed platform; the upper electrode 12 and the upper grip rod 15 can be raised and lowered above the fixed platform under the action of the driving source. Here, the base, the workbench, the driving source, and the upper and lower electrodes all adopt the structure of the existing ordinary spot welding machine. These are all existing technologies and will not be repeated here.

[0018] The invention of this embodiment lies in the addition of a floating platform. The floating platform includes a platform 2 and a driving mechanism that drives the platform up and down. The platform 2 is located between the fixed platform 11 and the upper electrode 12 of the spot welder, and the platform is open. There is a through hole 21 opposed to the lower electrode 13 of the spot welder.

[0019] The above-mentioned driving mechanism is two cylinders 3 arranged side by side, the top of the piston rod 31 of each cylinder is fixed to the bottom surface of the table 2, and the rodless cavity of each cylinder is connected with a pneumatic pressure reducing valve 4 at the same time, and the rodless of the two cylinders The cavity is also connected to a gas source (not shown in the figure) through a bypass (not shown in the figure).

[0020] In order to make the table surface rise and fall more smoothly, in this embodiment, the four corners of the lower bottom surface of the table surface are respectively fixed with guide columns 5, and each guide column is supported by linear bearings 6 on the fixed platform.

[0021] Before spot welding, the spot welding fixture c is placed on the table 2, and the fixture c has the function of automatically locating the welding spot, and the workpiece to be welded is placed on the fixture. At this time, the air source ventilates the cavityless rods of each cylinder through the bypass, and the piston rods of the two cylinders are simultaneously extended to lift up the table surface to be in a welding state. When the spot welding machine receives the spot welding command, the upper electrode moves down under the action of the driving source. When the upper electrode contacts the workpiece, it starts to apply pressure to the workpiece to be welded. This pressure is transmitted through the fixture and the table to make the cylinder free The rod cavity is pressurized, and the pressure of the rodless cavity of the cylinder is automatically relieved by the pneumatic pressure reducing valve. At the same time, the piston rod retracts, the table begins to drop, and the workpiece and fixture to be welded drop accordingly. When the workpiece and the lower electrode are When touched, the upper and lower electrodes contact and start spot welding. At this time, the upper electrode no longer moves down and the table top no longer drops. When the welding is completed, the upper electrode is reset, and the rodless cavity of the cylinder immediately takes in air through the bypass, causing the piston to extend and the table surface to rise to the welding state again, waiting to repeat the next cycle. In this way, the spot welding on the workpiece to be welded is completed in turn.

[0022] In the above embodiment, the pneumatic pressure reducing valve can also be an electromagnetic pressure reducing valve. In this case, a sensor that detects the upper electrode of the spot welder and applies force to the workpiece to be welded needs to be installed on the table. After the force signal of the electrode, the sensor transmits the detected signal to the controller of the spot welding machine, and the controller controls the opening of the electromagnetic pressure reducing valve; or, the driving mechanism adopts a driving mechanism composed of a motor, a screw rod and a nut pair , Through the forward and reverse rotation of the motor to achieve the purpose of lifting up and down the table. Therefore, any modifications and equivalent substitutions made within the spirit and principle of the present invention should be included in the protection scope of the present invention.