GB829122A - Improvements in or relating to mandrels for use in swaging operations - Google Patents

Abstract

829,122. Swaging mandrels. APPEL PROCESS Ltd. July 20, 1956 [July 21, 1955], No. 22500/56. Class 83 (4). A mandrel 5 for use in cold swaging a hollow workpiece 8, comprises an elongated rigid body 6 and at least one longitudinally-extending flexible rib 7 removably secured to the body so as to be withdrawn endwise from the finished workpiece whilst the body is retained in the workpiece. The mandrel enables workpieces with irregular internal surfaces, such as helical splines of varying pitch, to be made by swaging. For forming helical rifling of varying pitch in gun barrels, the mandrel may have a plurality of helical ribs 7a, Fig. 3, made of spring steel or piano wire located on the steel body 6 by circular or rectangular keys 35, 37. Alternatively the ribs may fit within shallow grooves 12, Fig. 2 (not shown), in the body. The latter is tapered at both ends 13, 14; at the forward end the ribs are anchored by a threaded plug 16 screwed within a sleeve 17 pressed against the end of the workpiece by a spring 24; at the rear end the ribs are clamped by a sleeve 20 co-operating with a conical plug 23 screwed on the threaded tailpiece 15 of the body. During cold swaging by hammer dies 30 in a rotary swaging machine, the workpiece is rotated by a chuck 28 engaging the notched end 27 of the workpiece. In another embodiment, Fig. 4 (not shown), the mandrel is tapered with axially extending ribs which terminate short of the forward-end of the mandrel. The ribs may also be of circular or triangular cross-section and they may taper throughout their length; they are preferably lubricated to facilitate their withdrawal. Alternatively the ribs may be secured to the body by soldering or brazing after location in a jig and may be subsequently released from the body by induction heating.