Abstract: The mandrel has a cylindrical body provided at the periphery with a plurality of jaws which are capable of radial displacement under the action of control means. Each jaw is supported by two radial columns which are capable of translational motion and each placed at one end of the jaw. Both support columns are driven by means of two first crank-arms rigidly fixed to two toothed wheels which are disposed in meshing engagement with each other, one toothed wheel being coupled with a second crank-arm. An actuating rod is mounted in the axis of the mandrel body and capable of translational motion along the axis, the rod being intended to actuate all the second crank-arms which correspond to the plurality of jaws.

Abstract: A furnace for heating a circulating gas stream to high temperatures comprising a tubular resistance-type heating element in contact with a stream of gas which is circulated outside and then inside the element, at least one annular and coaxial thermal screens surrounded by a cooling circuit, a leak-tight support casing which communicates with the external region of the heating element, an end-cap screwed into the casing and forming a nozzle from which the hot gases are discharged, and pumping means connected to the space between the open end of the tubular heating element and the end-cap.