Patent GB-352505-A (GB)
Title: Process of and apparatus for the manufacture of hollow bodies, especially tubes, by drawing over a mandrel
IPC: B21C45/00
Filed: 1930-04-10
Abstract: 352,505. Drawing tubes &c. METALLGES. AKT.-GES., Frankfort-on- Main, and FORSTER, H. VON, 22, Hohemarkstrasse, Niederursel, near Frankforton-Main, Germany. April 10, 1930, No. 11436. [Class 83 (iv).] Drawing-dies; separating mandrels from work.- A tube, or other hollow body e.g. casing, canister or cartridge, is drawn by dies 3 which are locked in the travelling tool carriage 8 when moved down to the extreme right and then pulled from right to left so drawing the tubular billet 2 while its inturned end is held by a stop 1a on the mandrel. A solid billet with pointed end to be gripped may also be used. The carriage 8 is reciprocated on a screw spindle 9 driven through an electrically reversable clutch 10 with reversing switch 12. The dies 3 may be drawn over the billet one at a time, the used die being left behind on the left end of the mandrel while the tool carriage is returned to the right by reversing the rotation of two threaded spindles after which another die is locked in it by the leveroperated locking gate 24 and is then drawn over the tube again. The die 3 may be alternated with oval dies, Fig. 12, to free the tube from the mandrel. The tube is finally stripped from the mandrel by turning in the strippers 14 in the tool carriage and then traversing this from left to right to scrape the tube off the mandrel. The used dies are then slid down the mandrel and on to a swinging die holder 15, the tool carriage is traversed to the extreme right and a fresh billet is shoved on the mandrel from the right end until its inturned end abuts against the stop 1a, the dies are threaded back on the mandrel and then locked in the tool carriage for the next drawing as before. The mandrel may be rotated while the work is hammered to free it from the mandrel. The mandrel is secured by its right-hand end during drawing by a divided clamp 4, Fig. 1, the two half bushes 45, Fig. 10, of which are screwed in or out by hand-wheel 58 to clamp or unclamp. An adjustable loosening device 16 may be fixed in the tool casing to effect loosening in a separate stroke of the carriage. The locking device 13 may be arranged to engage and push the dies into the carriage and lock them therein at one stroke. It may also act electromagnetically. In Fig. 4 a similar machine has four mandrels c<1>. . c<4> and other parts two sets of which are drawing tubes while the same stroke of the tool carriage is stripping the other two tubes. For good finish a smoothing die is drawn over the tube after loosening but before stripping. Another form of loosening and stripping tool, Fig. 13, may be secured in the tool carriage 8, being literally adjustable for the difierent bores the last bore 68 being a stripping bore. Other loosening dies may be in halves fixed in the swing- ing gate 31, Fig. 9, the hinges of which are mounted eccentrically to alter the loosening pass. The work is lubricated by a drip feed on the tool carriage, the used lubricant being led away and pumped back into the lubricator. Non-circular hollow bodies may be drawn.