Patent GB-536136-A (GB)
Title: Improvements in tube expanders
IPC: B21D39/10
Filed: 1939-11-02
Abstract: 536,136. Tube expanders. STIRLING BOILER CO., Ltd., and RUSSELL, C. H. Nov. 2, 1939, No. 29212. [Class 83 (iv)] A tube expander particularly for expanding and belling tubes extending only partly, through holes in tube plates, consists of rollers cooperating with a mandrel and carried by a body having a guard for engaging the end ot tne tube to limit movement of the body-into the tube and capable of inward movement relatively to the body while the body is being moved towards or from a tube expanding position, the guard being in the form of 'plungers slidable in transverse bores in the body with their longitudinal axes intermediate the axes of the roller recesses. A tool for expanding a tube 29 into a tube plate 26 and belling the end 30 into the enlarged intermediate part of the hole, consists of two expanding rollers 7 and combined expanding and belling rollers 17, 18, Fig. 6, mounted in slots in the body 1 and co-operating with a mandrel 5, the rollers being slightly inclined to to the axis of the tool. In the body are mounted a number of radially movable cylindrical plungers 2 which are pressed outwards by springs 3 engaging balls 4 in contact with the mandrel. The plungers are maintained in the body by leaf springs 11 fitting in recesses 13 in the threaded end of the shank 14 of the body over which screws a collar 16. The end 19 of the roller 17 is concave and the end 20 of the roller 18 is convex so as to interlock these rollers. The rollers may be held in the slots by a removable end plate 23 or may be moved radially inwards so as to be disengaged from the body. The mandrel is provided with a plate 24 to prevent movement of the body therefrom so that it may be used as a handle. In operation, the inner end of the body 1 is inserted through the portion 28 of the hole in the tube plate which is of smaller diameter than the rest of the hole. The plungers 2 and leaf springs 11 are pushed inwardly so that the outer end of the body is introduced into the hole. The mandrel 5 is then operated to effect the expansion. When the mandrel reaches the final position the plungers maintain contact with the end 31 of the tube to prevent further movement of the tool therein. In another form, the upper end of the body is closed by a cover plate 32, Fig. 7, provided with slots to guide a number of radically movable plungers 38, which are moved inwardly by the operator to allow the tool to be inserted in the hole. During operation the mandrel engages the inner ends 41 of the plungers and moves them outwards so that at the end of the expanding operation they come in contact with the end 31 of the tube 29. The tool of the operation is withdrawn upwardly from the hole, bevelled edges 40 on the plungers engaging the sides of the hole so as to move them inwardly. When operating in tube plates having entry holes 28 of sufficient diameter, the plungers may be so arranged that in their inner positions they overhang the end 31 of the tube. In a modification of this form, cylindrical plungers 42, Fig. 12, are used having enlargements 47 on the heads for limiting the inward movement and having split rings 46 engaging counterbores 44 in the body 1 for limiting the outward movement.