Butt welding apparatus

In an apparatus for the electric butt welding of a workpiece having rod-like ends;

• the apparatus including a machine frame;
• at least two welding electrodes;
• means for bringing the electrodes into contact with the workpiece;
• two upsetting tools for supporting the workpiece;
• means for movably supporting at least one of the upsetting tools to be displaceable in the upsetting direction;
• an upsetting device connected to and actuating the upsetting tools;
• a control means for controlling the course of motion of the electrodes and the upsetting tools and for controlling the welding current as well as the upsetting device;
• a force measuring device connected to the movable upsetting tool for sensing the pressing force exerted by the upsetting tool on the workpiece;
• means for setting a desired value of the pressing force;
• a switch coupled to the force measuring device to be actuated by the force measuring device when the desired value of the pressing force is reached;
• and a welding circuit including the switch for effecting the flow of welding current when the desired value of the pressing force is reached;
• the improvement wherein said means for movably supporting at least one of the upsetting tools includes a sleeve pivotally secured to the machine frame;
• said movable upsetting tool being slidably supported in said sleeve;
• a carriage displaceably supported on said machine frame;
• said control means including a force exerting means for urging said carriage against said movable upsetting tool for imparting a pressing force by said carriage on said movable upsetting tool when the latter is in an operational position;
• said carriage being connected with said upsetting device;
• said control means further including a force transmitting means connected to said force exerting means and said force measuring device;
• said force measuring device being connected to said carriage for applying thereto a force derived from the force exerted by said force exerting means to said force measuring device through said force transmitting means;
• said force measuring device being operatively connected to said switch for actuating said switch when the desired value of the pressing force is reached.