GB298407A - Method and apparatus for drawing tubes - Google Patents

Abstract

298,407. Fulton, W. M. Dec. 9, 1927. Drawing; mandrels. - Tubes are drawn between a reciprocating mandrel and die, the mandrel moving with the tube while the latter is being drawn through the die, and the drawing action being intermittent so that the mandrel acts on successive portions of the tube. Alternatively, the die may reciprocate, and the mandrel remain stationary. The mandrel 46 is mounted on a bar 43 pivoted in a crank-operated crosshead 36 which carries a notched bar 78 whereby intermittent longitudinal movement is transmitted through a pawl 85 to the drawing head 69. A further pawl 95 is mounted on the draw-head to coact with teeth 94 to prevent retrograde movement of the draw-head during the idle stroke of the crosshead, and a hand-lever 91 is provided for disengaging both pawls 95, 85 so that the draw-head may be moved to its initial position. The die 53 is secured by clamps in a holder 49 mounted on a die block 48, the latter being linked at 56 to a hand crank 61, whereby the die-block may be moved clear of the end of the mandrel. A spring 45 lifts the mandrel bar, when clear of the die block, in order that it may receive a tubular blank whose end has been previously reduced, as by swaging, to pass through the die. The mandrel is then lowered, the hand crank 61 actuated to carry the die block over the tube end, the hand crank being then locked in this position throughout the drawing operation. The drawhead is then moved up to the tube, a flexiblymounted plug 76 being inserted in the tube end to withstand the collapsing pressure exerted by the screw actuated pivoted gripping jaw 73. The pawls 85, 95 are then recorded operative and the machine started. In a modification, particularly for drawing tubes of small bore, the mandrel is carried by a tension bar 101, Fig. 10, secured to an eccentric pin 104 in a bracket secured to the notched bar 78, the eccentric being adapted to be operated by hand to engage the hook 102 with the mandrel and to ensure the bar 101 being maintained in a state of tension. This machine is stated to be able to produce tubes having a wall thickness of 0.005 inch or more.