PURPOSE: To enable exchange of upsetting tools with the mere need for removing just the slight lightweight device portions by bringing the upsetting tool into contact with the portion acting on the upsetting tool of an upsetting carriage by frictional connection.

CONSTITUTION: The upsetting tool 54 is arranged in a guide device 48 of a separate body and is separated from the carriage 12. The upsetting tool 54 comes into contact with the portion 42 acting on the upsetting tool 54 of the upsetting carriage 12 by frictional connection. The upsetting tool 54 may be easily removed and, in some cases, exchanged, as a unit body together with the guide device 48 by easily loosening the nut of a staybolt 66. Further, a clamping tool 76 may be easily exchanged after the unit body is removed.