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    Control of movable platen of flash-butt welding machine
    26.
    发明授权
    Control of movable platen of flash-butt welding machine 失效
    闪焊焊接机移动板的控制

    公开(公告)号：US3555237A

    公开(公告)日：1971-01-12

    申请号：US3555237D

    申请日：1968-03-20

    Applicant: TAYLOR WINFIELD CORP

    Inventor： RILEY JOSEPH J

    IPC: B23K11/24 ,  B23K11/04

    CPC classification number: B23K11/246

    Abstract: A solid state control system for a flash-butt welding machine for controlling a movable platen clamping a workpiece to effect ''''forward'''' and ''''retract'''' movements with respect to a stationary platen clamping a stationary workpiece, through the medium of an electrohydraulic servo valve. Said control system involves a novel, highly responsive switching circuit which allows reversal of valve current and resulting oil flow by the use of only two transistors, which current reaches adjusted maximum value almost instantaneously, and which circuit includes a logic feature, such that when one transistor is switched ''''on,'''' the other is automatically switched ''''off.'''' The circuit also consists of potentiometers and diodes shunting them, in series with the servo valve coil, such that one potentiometer setting for maximum coil ''''retraction'''' current has no influence on the other potentiometer setting for maximum coil ''''forward'''' current, making the settings independent of each other. The control system also involves an indicator circuit consisting of transistors and highly responsive neon lamps which indicate valve current reversal up to double line input frequency. The control circuit also includes an input or feedback circuit from the welding dies, rectifying the voltage which is applied to a schmitt trigger so that the ''''forward'''' switching transistor can be made to conduct over an interval of 150 to 0 electrical degrees through adjustment of a potentiometer in conjunction with the setting of another potentiometer through a 3 to 1 input range of welding die voltage. This input circuit may include a capacitor to allow the forward switching transistor to conduct through the full 180* interval so as to reduce valve mechanical wear and yet be responsive to a reduction in die voltage if the workpieces butt sufficiently hard to reduce weld resistance and die voltage.

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