770,577. Making pipe bends. WESTERN ELECTRIC CO., Inc. Feb. 23, 1955 [March 11, 1954], No. 5426/55. Classes 83 (2) and 83 (4). [Also in Group XL (b)] Apparatus for shaping a sharp angular bend in the inner wall of a bent rectangular tube and also for forming a transverse corrugation or dimple in the bent portion of the outer wall of the bent tube comprises a mandrel slidably insertable in the tube and bearing at its inner end a pivotally mounted cam for shaping the bent portion of the inner wall of the tube and a slidably mounted section for shaping the bent portion of the outer wall of the tube, the slidably mounted section being provided with a dimpling concavity co-operating with a dimpling die positioned outside the bent portion of the outer wall of the tube to produce the said transverse corrugation or dimple. The apparatus comprises a base 12 having guide and support members 13, 14, 16 and 17 and die sections 18, 19, 21, 22 and 23 defining a rectangular die cavity 24 for receiving the bent rectangular tube 26 (Fig. 6). A convex dimpling die 27 is slidably mounted between the die sections 19 and 21 and an angular forming die 31 is similarly mounted between the die sections 22 and 23. A wedge member 33 is movable between the support member 13 and die section 23 and engages with the forming die 31. A slide block 36 moves between support members 14 and 16 and has a longitudinal passage 41 restricted at 50 to form an annular seat. The passage 41 and a longitudinal aperture 42 in the slide block interconnect with a cavity 39. The front of the slide block carries a collar 38 provided with a projecting arm 44 engageable with the wedge member 33. The mandrel 48 has an enlarged extremity 49 mounted in the slide block cavity 39 and is provided with a longitudinal aperture 66 alignable with the aperture 42 in the slide block. The forward end of the mandrel is provided with an arcuate cavity 51 and a slot 52. An arcuate cam 53 is rotatably mounted in the cavity. A longitudinal passage 56 in the mandrel connects the slot 52 with the passage 41 in the slide block. The front of the mandrel has an inclined plane surface 57 formed with a groove 58 for accommodating a slidable forming section 59 provided with a concavity 64 which in the operating position opposes the dimpling die 27. A locking-pin 67 secured in the aperture 42 of the slide block extends through an aperture 66 in the mandrel and locks the forming section 59 in position on the mandrel. A cam block 68 slidably mounted between support members 14 and 17 is provided on one extremity with a first inclined surface 69 for engagement with an inclined surface 43 on the slide block and a second inclined surface 71 engageable with an inclined surface 20 on the support member 17. A ram 73 slidably mounted between support members 14 and 17 is slidably keyed to the cam block 68. A cam rod 76 secured to the ram extends through an enlarged passage 72 in the cam block and through the slide block and mandrel. An enlarged portion 70 of the rod abuts with the annular seat 50 in the slide block. Secured to the end of the cam rod is an annular cam 77 slidably mounted in the mandrel slot 52 for actuating the arcuate cam 53. An actuating bar 78 slidable in a passageway 40 in the slide block has an inclined front surface 79 engageable with an inclined surface on the dimpling die 27. In operation, the mandrel is fed into the initially bent tube by actuating the ram 73, whereupon the locking pin 67 locks the slidable section 59 in position and the wedge member 33 forces the forming die 31 into engagement with the inner wall of the tube. Additional forward movement of the slide block is prevented and the second inclined surface 71 of the cam block 68 is adjacent the inclined surface 20 of the support member 17. On continued movement of the ram the cam block angularly moves into the space 45 to allow the cam rod 76 to advance and rotate the arcuate cam 53 into engagement with the interior of the tube opposite the forming die 31, thereby sharpening the angular configuration of the inner wall. Also, the actuating bar 78 advances to actuate the dimpling die 27 to produce the transverse corrugation of dimple in the outer wall. After the forming operation reversal of the ram retracts the cam rod and also the slide block when the enlarged portion 70 of the rod abuts the seat 50 in the slide block. The locking pin 67 is removed from the depression 62 to unlock the slidable section 59 and when the enlarged portion of the mandrel has taken up the play in the cavity 39 the mandrel is retracted. The slidable section 59 moves in the groove 58 to clear the dimple in the outer wall of the tube and the arm 44 unlocks the forming die 31 to enable the formed tubular bend to be removed from the die sections. Specification 765,173 is referred to.