Stud welding method and stud welding device particularly for stud welding without a support foot

Abstract

The invention relates to a stud welding method, particularly for welding without a supporting foot, which makes it possible to securely detect the presence or the absence of a part to be welded in the stud holding device. For this purpose, in a first embodiment of the method, the stud holding device is first positioned in a pre-determined distance relative to the surface of the workpiece without a part to be welded. Then, a part to be welded is supplied. When the welding axle moves towards the workpiece, the distance which has to be covered until the part to be welded contacts the workpiece is detected. On the basis of the previously determined distance between the stud holding device and the workpiece and on the basis of the distance covered conclusions on the presence or the absence of a part to be welded may be drawn. In another embodiment, the stud holding device is moved towards the workpiece together with a part to be welded until a contact is detected. If, after detecting the contact, it is possible to further move the welding axle into the stud holding device as a result of a displacement of the part to be welded, this will be interpreted as an indication to the presence of a part to be welded. Furthermore, the invention relates to a device for caring out the method and to a computer program for an evaluation and control unit of generally known welding devices.

1 - 27 . (canceled) 
   
   
       28 . A stud welding device for connecting welding studs to a workpiece, comprising:
 a footless welding head movable along an axis relative to the workpiece, the welding head including an electrical contact for generating an electrical interaction between the welding head and the workpiece;   a stud holding device cooperable with the welding head for holding the welding stud;   a drive device cooperable with the welding head for moving the stud holding device in relation to the workpiece until an electrical contact between the stud and the workpiece is detected;   a controller connected to the drive device and the welding head for controlling movement of the drive device and the welding head relative the workpiece.   
   
   
       29 . The stud welding device of  claim 28  wherein the stud positioned in the stud holding device provides an electrical contact with the workpiece to determine if a part is present in the stud holding device. 
   
   
       30 . The stud welding device of  claim 28  including a strain sensor associated with the welding head for detecting an increase in the force applied by the drive device for verifying the presence of the stud in the stud holding device. 
   
   
       31 . The stud welding device of  claim 28  including a power consumption sensor associated with the welding head for detecting a power used by the drive device for verifying the presence of the stud in the stud holding device. 
   
   
       32 . The stud welding device of  claim 28  wherein the welding head is axially displaced relative to the drive device following contact with the workpiece.