Patent GB-227860-A (GB)
Title: An improved plate bending machine
IPC: B21D5/14
Filed: 1925-01-17
Abstract: 227,860. Thompson & Co. (Castle maine) Proprietary, Ltd. Jan. 19, 1924, [Convention date]. Curving; bending-dies.-A machine for bending metal plates, particularly for making pipes consists of three rolls of different diameters, two of the rolls, functioning as driving rolls, having a constant relationship to each other and being adjustable with respect to the third which functions as a pressing roll. The lower rolls 19, 20, which have their axes in the same horizontal plane and may be geared together, and which are rotated by a spur wheel 24 carried by either of their shafts, are mounted in pedestals 14, which are transversely adjusted on a bed 10 by screws 15 to determine the radius of curvature of the plate to be curved. The inner ends of the pedestals abut against locating wedges or distance pieces inserted in front of abutments fixed to the bed. The rolls rest on roller supports 51 which are slidable therewith during adjustment. The upper roll 40 is mounted in bearings 43 carried bv rods 44 which are secured to crossheads 46 having plungers 47 sliding in cylinders fixed to forward extensions of columns 11 projecting from the bed. The cylinders are connected by pipes 49 direct to a source of hydraulic pressure so as continuously to tend to raise the roll against rolls 42 in the heads of rams 25. The roll is pressed down by the rams, the cylinders of which are connected by isolating-valves 39 and a pipe 34 to a control valve 29 communicating with the source of pressure. The valve has three chambers and the plunger 32 is operated by a hand lever to connect the pipe 34 with either of the pipes 35, 36, which are connected respectively to the supply and exhaust, the plunger for this purpose having a hollow plugged end provided with two series of ports 38. Other means may be used to apply pressure to the roll 40 and the roll may be raised by springs &c. After adjusting'the rolls 19, 20, the plate is inserted so that its edge is positioned by longitudinal flutes in the rolls, pressure is then supplied so as to grip the plate between the rolls 20, 40, and the rolls 19, 20 are rotated backwards and forwards and the pedestals adjusted until one half of the plate is of the desired curvature. The larger of the lower rolls is disposed at the rear of the pedestals 14, and the plate is initially set so that its edge is placed in line with the axes of the upper roll and rear roll. The initial operation causes the extreme edge of the plate to assume the required curvature in addition to the body of the plate and thus avoids the necessity for a separate curving of the edge. The plate is then reversed and the other half then curved. In order to rectify any lack of uniformity in the curvature due to variations in the hardness or thickness of different parts of the plate one or other of the isolation valves is adjusted so as to relieve the pressure at one end of the machine. The rolls are all mounted in bearings of similar size so as to be interchangeable with each other and so increase the range of adjustment. In making medium sized or large pipes, two or three plates may be curved and then welded by the electric are, but in the case of small pipes a single plate may be curved round the roll 40 and subsequently electrically welded to complete the pipe. A previously curved plate may be placed between the roll 40 and its bearing rolls 42 to form a space for the admission of the plate being curved. The pipe may be stripped from the roll 40 without removing the roll or its bearings, by using a bearing with a narrow neck 53 over which the pipe is drawn by hauling tackle &c. In making small pipes the machine may operate either by roll. bending or by press bending; in the latter case the rolls are not rotated. The Specification as open to inspection under Sect. 91 (3) (a) describes a modification for making small pipes, in which the upper roll is replaced by an I-beam 54, Fig. 8 (Cancelled) carrying a former 55, bending being effected to the curve of the former, by gradually passing the plate under the former, which is alternately raised and lowered so as to bend the plate against the lower rolls, which are not rotated and serve as bending blocks. This subject-matter does not appear in the Specification as accepted.