Patent GB-757157-A (GB)
Title: Apparatus for and method of making tubular bellows elements for expansion joints
IPC: B21D15/10
Filed: 1954-07-27
Abstract: 757,157. Making bellows and corrugated pipes. ZALLEA, J. P. July 27, 1954, No. 21923/54. Classes 83 (2) and 83 (4). [Also in Group XXVIII] Stamping.-A process of forming from a round tubular blank a one-piece bellows element having axially aligned cylindrical portions and an annular corrugation disposed therebetween, said corrugation being of oval crosssection includes the step of initially annularly corrugating an intermediate portion of said blank, the depth of said corrugation being greater than its width, the step of reinforcing axially spaced portions of the blank on opposite sides of the initial corrugation against outward deformation and the step of moving said reinforced portions towards each other and of outwardly deforming said annular corrugation by fluid pressure, preferably at five times the operating pressure, while it is unconfined to shape said initial corrugation into a final oval form. The initial corrugation is formed in a press 10 having upper and lower platens 11 and 12 between which the tubular blank is disposed. The ends of the blank are sealed by members 18 and 24 and sealing rings 23 and 28. The member 24 has a nipple 30 for supplying pressure fluid to the interior of the blank via a threeway valve (not shown) and the member 18 has a nipple 14 communicating with a vent 17. Dies 34 and 35 surround the upper and lower ends of the blank respectively and have depressed surfaces 39 and 40 for forming the initial corrugation. In operation, pressure fluid is passed into the blank from the supply conduits 32, the sealing rings are compressed and as the blank begins to bulge the platen 12 is moved towards the platen 11 to form the initial corrugation as shown in Fig. 2. Die rings 46 and 47 welded to platen supported members 48 and 49 are now substituted for the dies 34 and 35, (Fig. 2), and fluid pressure again internally applied to the blank whilst the platen 12 is raised towards the platen 11 to shape the unconfined corrugation to its final oval shape. For securing the bellows element' in a pipe line, sleeve members 56 and 57 are welded to the tubular end portions and a bolting flange 63 may be welded to the sleeve members (Fig. 5). Alternatively, the sleeve members may be secured to the initially corrugated blank which is then placed in the press as shown in Fig. 21 and the corrugations shaped to their final form. When manufacturing a plurality of similar bellows elements having the same flexing life a first bellows is made as above described and tested and if satisfactory the fluid pressure used and the movement of the platen 12 is noted. Fresh blanks are then set up in the press which has die members 65 and 66 (Fig. 7) substituted for the die members 34 and 35, said die members 68 and 66 comprising die rings 67 and 68 welded to platen supported members 69 and 70, the latter member carrying a spacer 73. Fluid pressure equal to that used in the test bellows is supplied to the interior of the blank and the platen 12 is simultaneously raised the required distance to form an annular corrugation similar to the test blank. For making a bellows element having a plurality of corrugations a cylindrical blank 74 is placed in a press having upper and lower die members 75 and 76 and a pair of intermediate die members 77 and 78 (Fig. 8). The upper and lower dies have recessed surfaces 79 and 80 for accommodating removable annular filler members 87 and 88. Each intermediate die member comprises a reinforcing collar 90 and a circular rim 95 provided with a web 96 for carrying removable annular filler member 97. Fluid pressure is applied to the interior of the blank and the platen 12 simultaneously moved towards the platen 11 to form the initial. U-shaped corrugations (Fig. 9). Finally, the filler members are removed and the blank once more subjected to internal fluid pressure to form the oval corrugations (Fig. 11). The reinforcing collars form part of the finished bellows element and the ends of the element are prepared for connecting into a pipe line as hitherto. For manufacturing a plurality of similar bellows elements having multiple corrugations and each having the same flexing life an experimental bellows is made as above described and then cylindrical blanks 99 (Fig. 13) are placed in the press which has been provided with thinner filler members 102, 103 and 104 and the interior of the blank is subjected to the same fluid pressure and platen movement as used in the experimental bellows. For making a bellows element over six feet in diameter an initially corrugated cylindrical blank having collars 106 and end sleeves 108 welded thereto is placed around a cylindrical body 114 and inserted between platens 115, 116 of the press. The body 114 comprises upper, lower and intermediate sections 119, 120 and 121 respectively adjustably secured together and the upper and lower ends are slidable over guide rings 118 on the platens. Sealing rings 126 ensure fluid-tight seal in the annular space between the bellows element and body 114 which is provided with nipples 129 for supplying the fluid pressure. In operation, with the initially corrugated blank positioned in the press as in Fig. 15, the bolts attached to the cylindrical body are drawn up to partially close the base of the corrugations and to compress the sealing rings 126 and fluid pressure is introduced to shape the corrugations to ovaloid form (Fig. 17). Alternatively, the cylindrical body may be in one section 130 and having annular members 132 which are welded to an initially corrugated and axially compressed blank 105 (Fig. 20). After the forming operation the annular members are cut through to separate the bellows element. A bellows element having multiple corrugations may be formed by welding together a plurality of onepiece bellows elements as shown in Fig. 19. In a still further embodiment the initially corrugated blank as shown in Fig. 16 may be installed in a pipe line and then the fluid pressure is applied to bulge the corrugations to final form.