Patent ID: 6027007
Filing Date: 2000-02-22
Classification: B23K

Abstract:
A device for internally butt-welding pipes, of the type comprising a support and guide frame for an annular welding member rotatable coaxially to the pipes to be welded, and carrying a plurality of welding heads, the device comprising at least one sensor connected to a unit for controlling the movement of said member and arranged to sense the presence of said heads at predetermined points, said sensor (15) comprising a first part (5) arranged to emit a signal and a second part (6) arranged to modify said signal, said two parts being provided respectively in seats (7) provided in said support and guide frame (2) and in said annular welding member (3), said two parts being arranged in such a manner as to remain permanently separated from each other, said sensor (15) being of inductive type, the first part (5) of the sensor comprising an electromagnetic field generator, the second part of the sensor and the member (3) or the support and guide element in which said second part (6) is housed being constructed of materials the magnetic characteristics of which are different from each other.