GB1050171A - - Google Patents

Abstract

1,050,171. Making elbow fittings; stamping; angular bending; upsetting. GRINNELL CORPORATION. March 18, 1964 [March 28, 1963], No. 11376/64. Headings B3A. B3E. B3H and B3Q. A method of forming a hollow elbow fitting from a tubular section comprises bending the section, placing the bent portion in a die, expanding the end portions adjacent the bent portion and forcing them towards the bent portion by driving in plunger means and expanding the bent portion by pressure so as to conform to the interior of the die. In an example a length of soft copper tubing is initially located in arcuate grooves 32, 34 subtending an angle of 120 degrees, formed in the top face of two pivoted blocks 22, 23 so that it is penetrated by an adjustably spring biased plug 20. A ram 46 is lowered to bend the tube. The ram is forked and has concave surfaces 46 inclined at 90 degrees to each other and side plates 44 which constrain the tube against bulging. Partial collapsing of the tube during bending moves the plug against the preset spring 64. Subsequently the bent portion is severed from the tube length, removed from the initial bending unit and located in a cavity 90, defining a finished elbow having slightly longer end portions formed by a pair of dies 86, 88 of a fluid pressure unit, Fig. 11. The die 88 is attached to a vertically movable press ram. A pair of fluid operated plungers 104, 106 are initially advanced into openings of the bent portion, the end faces being engaged by the plunger shoulders 104b, 106b which displace the protruding portions into the die flush with the faces 124, 126 and square off the end faces of the fitting. Subsequently fluid at 10,000 p.s.i. is admitted, via a duct 144 in the plunger 104, into the fitting to expand its curved portion and produce a slight shortening of the socket portions into the die to form a finished fitting. In a modification the tubing is pre-cut to length and a plug mounted on each of the pivoted blocks, one of which is axially adjustably mounted on a base to facilitate loading (Fig. 18, not shown). In a further modification expansion of the curved portion of the bent portion is achieved by using angled rubber blocks, one being detachably secured to the end of each plunger, which expand against one another during the latter part of the plunger stroke (Fig. 21, not shown). Alternatively only one rubber block is used which is located in a sleeve initially advanced into one end of the fitting, the plunger being subsequently advanced to move the block into the fitting and effect expansion thereof against the end face of the other plunger (Fig. 23, not shown).