Patent GB-769612-A (GB)
Title: Apparatus for shaping bends in tubes
IPC: B21D22/02
Filed: 1955-02-23
Abstract: 769,612. Making pipe bends. WESTERN ELECTRIC CO., Inc. Feb. 23, 1955 [Feb. 26, 1954], No. 5425/55. Classes 83 (2) and 83 (4). [Also in Group XL (b)] Stamping.-Apparatus for converting a smooth curvilinear bend in a rectangular tube into an angular bend provided with transverse corrugations or dimples, is characterized in that the bent tube is internally supported in a die cavity with its bent portion between a first reciprocally mounted die for forming the inner wall of the angular bend and a second reciprocally mounted die for forming and dimpling the outer wall of the angular bend and in which the two dies are simultaneously actuated to convert the smooth bend in the tube into a dimpled angular bend in a single operation. The apparatus comprises a base 16 and a die block 17 comprising die sections 18, 19, 21 and 22 defining an angular die cavity 24. The forming and dimpling die 31 is slidably mounted between die sections 18 and 19 and is hydraulically actuated. An operating head 37 carries a convexforming head 38 and is reciprocable in a slideway 39 by hydraulic means 42. The interior of the tube is supported by a mandrel made up of sections 47, 48, 49 and 51. The mandrel section 47 has a tongue 52 and is inserted into one arm of the bent tube until a shoulder 53 engages the die section 21. The other mandrel sections fill the other arm of the bend. Mandrel section 48 has an inclined surface 54 for supporting the interior of the tube wall opposite the forming surface 46 of the head 38 and a groove 56 for receiving the tongue 52 on the mandrel section 47. It has also a concavity 57 complementary to the dimpling projection 33 on the die 31 and a shoulder 58 for engaging the die section 22. The mandrel section 49 has an inclined surface 59 for supporting a portion of the tube wall opposite the forming surface 32 of the die 31, a concavity 61 similar to the concavity 57 on the mandrel section 48 and an inclined cam surface 60. A shoulder 62 on the mandrel section 49 engages with the die section 18. The mandrel section 51 consists of a wedge portion 63 for insertion between the mandrel sections 48 and 49 and a rectangular portion 64 for abutment with the shoulders 58 and 62 on the mandrel sections 48 and 49. An inclined portion 66 on the section 51 supports the remaining unsupported portion of the tube wall opposite the forming surface 32 of the die 31. The mandrel sections are retained in their assembled positions by slide members 69 which are slidably inserted in grooves 28 in the die sections and aligned slots in the mandrel sections. A top plate 71 (Fig. 3) is clamped on the die block 17 to hold the tube in position during the forming operation. Actuation of the head 37 and die 31 effect in a single operation an angular forming of the tube and a dimpling of the corners on the outside wall. In another embodiment the operating head 94 has a die 96 (Fig. 7) and the bent tube 100 is supported by two side-engaging composite mandrels 101 slidably mounted on the base 81 by retaining sleeves 105. The mandrels 101 comprise reciprocable arms 102 operating members 103 and arcuate cams 104. The arms 102 and their slidable sections 107 are provided with arcuate surfaces 108 and 109 respectively (Fig. 9) which in the assembled position define concavities 111 complementary to the dimpling projections 93 on the die 89. In operation, actuation of the head 94 forces the mandrels into their final position in the bent tube and the members 103 rotate the arcuate members 103 to the position shown in Fig. 8. Simultaneously with the actuation of the head 94, the die 89 is moved into engagement with the tube to flatten the bend and form dimples or corrugations at the outer corners as shown in Fig. 12.