Patent GB-676048-A (GB)
Title: Improved method and means for shaping sheet metal blanks
IPC: B21D15/10
Filed: 1950-05-26
Abstract: 676,048. Stamping. EMBOUTISSAGE HYDRAULIQUE MODERNE. May 26, 1950 [June 18, 1949], No. 13354/50. Classes 83 (ii) and 83 (iv). A hollow article is made from a cylindrical blank having the same surface area and wall thickness as the required article, by filling the blank partly with an incompressible liquid and partly with a plunger extending through a sealing member, which also serves to clamp the upper end of the blank, and then by deforming the blank to the required shape, the volume of the filler being maintained at such a level that the material of the blank does not stretch but at the same time is prevented from becoming pleated or inwardly bulged. In order to make a reel of the form shown in Fig. 5, a blank 1A (Fig. 6), is placed in a split die 3A and is closed and held at its upper end by a member 4A through which passes a compensating plunger 5A beneath which is a body of water. A punch 2A is then raised, thus forcing up the body of the blank until it attains the required shape. The operation is preferably carried out in the press shown in Fig. 7. Between horizontal columns 11 are arranged a stationary table 12 and yoke 13 and a movable plate 10. On guides, not shown, between the plate 10 and table 12 are plates 14 and 15 carrying frusto-conical hoops 20, 21 adapted to cooperate with similar surfaces at the ends of a split die 22. The cylindrical blank, filled with water, is mounted in the die as shown, the outer sides of the hoops being connected by a flexible wall 23 which forms a water tank. On the first inward movement of the plate 10, members 27 act through rollers 19 and linkages 17, 18 to move the plate 15 towards the plate 14 so that the die is clamped between the hoops 20, 21 and the top of the blank is clamped between the die and the sealing member 25. On further movement of the plate 10, the punch 24 contacts the lower end of the blank and deformation of the blank begins, the compensating movement of the plunger relative to the blank being controlled by air pressure between pistons 28 and 31 and by air pressure in a cylinder 40 acting on an annular piston 41 from which rods 42 pass through the table 12 and contact the plate 14. During the pressing operation the piston 31 is adjusted by an axial movement of a nut 34 through levers 35 controlled by cams 36 coupled to rods 37 moving with members 27. Towards the end of the operation the withdrawal of the plunger 26 is suddenly stopped by a collar 29 abutting the table 12, causing a sudden rise in pressure within the blank, thus pressing it firmly against the die 22 and plunger 24. A double-grooved pulley may be made from a cylindrical blank 62 by the stationary die 64 and movable die 65, Fig. 11. If the pulley grooves are to be of unequal diameter the cylindrical blank has portions 71a and 72a of diameters equal to those of the required grooves as shown in Fig. 13. A step in the manufacture of a vehicle wheel of the form shown in Fig. 14 consists in expanding a water-filled blank of the shape shown in Fig. 17 in a die 88 by means of a punch 91 having its upper surface shaped to produce the part 85 of the wheel. The blank of Fig. 17 is made from a plain flanged cylindrical blank having a diameter equal to that of the required rim and a surface equal to that of the finished wheel by first reducing the lower part to a smaller diameter equal to the diameter of the groove 82 and then by dishing the bottom as at 87 and shaping the top as at 86.