Patent GB-578204-A (GB)
Title: Method and apparatus for controlling machines operating periodically on a continuously moving piece of material
IPC: B23D36/00
Filed: 1944-03-08
Abstract: 578,204. Photo-electric control of machine operations. LOEWY ENGINEERING CO., Ltd., and FERNBACH, H. R. March 8, 1944, No. 4282. [Class 40 (iii)] [Also in Groups XXII and XXXVII] An operation to be performed repeatedly on moving material is carried out at intervals under the control of an oscillating member which is driven at a speed related to the forward movement of the material so that operations are performed as equal successive lengths of the material pass the point at which the operation is effected. The invention is described as applied to a shear 10, Fig. 1, of the type which is stopped for each cut. The oscillating member 20, of disc form, has an arcuate slot 22, Fig. 2a, the effective length of which can be determined by adjustment of a sector-shaped mask 80. Disc 20 is secured on a shaft 21 which is driven through a reversible drive, Fig. 1a, from the shaft of a feeding roll 14 by which material is continuously advanced to the shear. The direction in which disc 20 is rotated is determined by which clutch winding 35 or 36 is energized, and this is determined in turn by the obturation of a photo-electric cell 23 disposed opposite the track of slot 22 so as to receive light through the slot from lamp 24. Fig. 3 shows the control circuit. To prepare for operation, switches J, K are closed, the latter bridging contacts J1 ... J3 and J4, J5. Relay G operates to energize the shear brake coil 13. Operation of push-button H energizes relay F which locks over the shear limit-switch I, connects up the shear clutch magnet 12, energizes relay B and releases relay G. Relay B locks over contacts J5, J4, B1, J3, J1, connects the power supply to the photo-electric unit 50, and energizes relays C, E. The circuit of relay E includes contacts D 1 of relay D which is of the kind which only operates its contacts (alternately opening and closing them) at each de-energization of its winding (see Group XXXVII). Relay E connects up clutch magnet 35 so that disc 20 begins to move in a counter-clockwise direction as seen in Fig. 2a. The light beam X from lamp 24 is thus allowed to fall on cell 23, causing relay A to operate and energize relay D, releasing relay C. When limit switch I opens, relay F releases and energizes relay G to stop the shear. Disc 20 continues to rotate until the light beam is obscured when relay A releases to energize relay C which re-operates relay F and re-starts the shear. At the same time, relay D is released, opening its contacts D1 and de-energizing relay E which replaces clutch magnet 35 by clutch magnet 36 so that the disc 20 moves in the opposite direction. Relay A operates again when the light falls on cell 23 energizing relay D and releasing relay C. The operation thus continues with the disc 20 oscillating under the control of clutch magnets 35, 36 which are alternately energized by the change-over of contacts D1 at the end of each movement. The interval between successive operations of the shear is determined by the setting of mask 80 on disc 20, so that the lengths cut by the shear from the moving strip can be adjusted. False operation is prevented by arranging that disc 20 always returns to an end position when the machine stops. In the Provisional Specification it is stated that instead of a photo-electric control, the member such as disc 20 may comprise limit switches which are in contact with cams on the disc.