Patent GB-544142-A (GB)
Title: Improved stretching machine for flattening metal strip
IPC: B21D25/00
Filed: 1940-09-24
Abstract: 544,142. Stretching strip metal. HEAD, WRIGHTSON & CO., Ltd., and LAKE, N.C. Sept. 24, 1940, No. 14521. [Class 83 (iv)] Straightening winding. A machine for stretching metal strip supplied in the form of a coil comprises a device for uncoiling, levelling and recoiling the strip, and two gripper heads for gripping the opposite ends of the strip, together with operating means by which after one end of the strip is secured to one of the heads the head is moved away from the uncoiling device during uncoiling, and then the other end of the strip is secured to the other head and the heads separated to stretch the strip and finally the strip is released from one of the heads and recoiled, the other head during this operation being moved towards the recoiling devices. The machine comprises a travelling gripper 4, a hydraulically actuated gripper 5 for effecting the stretching operation, a roller straightener 8 and a coiling and uncoiling device. When stretching heavy gauge strip the coil is placed on rolls 7 which together with the straightening coils 8 are driven through universal joints by gearing from an electric motor 9. The coil further rests on idle coils 42 and is centred by adjustable side guards 43. The rolls 7 and upper row of rolls 8 are carried by bearing blocks 15 pushed down over guide rods 16 against the action of springs 17 or hydraulic cylinders by wedges 18 operated by a lever 221 from a pneumatically or hydraulically operated cam 19. The stroke of the cam is adjusted by mounting a shouldered sleeve 28 on the rod 27 connecting the wedges, the shoulder engaging an adjustable stop in the form of a flange 30 on a screwed collar 31 which is provided with an operating handle 33 and a cocking handle 34 co-operating with a scale 35. The roll 81 is independently adjusted by fluid pressure or by worm or bevel gear operated screws 37 so that it might be raised to bend heavy gauge material during recoiling. When operating on light material the coil is mounted on an expansible drum 3 driven by a motor 46 through gearing and provided with a de-clutching means so that it may free wheel driving uncoiling. The motor may be of the variable speed type and provided with a slipping clutch so as to compensate for the growth of the coil. The travelling gripper 4, which is driven by a motor 62 and winch 61 through endless chains of rope gear with a slipping clutch so as to compensate for speed variation between the winch and coiler, carries pivoted hooks 56 provided with balance weights 57 and during stretching engaged in undercut notches 6 and in the bed. These notches are formed to a curved undercut shape by boring or turning. During traverse of the gripper 4 the hooks are held out of action by latches 58. To prevent damage due to sagging of the strip between the gripper 4 and coils, the gripper carries cam plates 66 engaging rollers 65 carried by pivoted arms 64 so as to swing the arms across the bed, the arms being held by over-centre springs 69. When the gripper moves towards the coiler rollers 71 thereon engage the arms to swing them out of the way. The arms are provided with strip supporting rollers 73. In operation the coils 8 are lowered, the end of the strip is fed from the coil through the straightening rolls and the end clamped in the gripper 4 whereupon the gripper and uncoiler are driven until the other end of the coil is drawn into the straightening rollers. The coiler and gripper are then reversed and the free end of the strip passed into the jaws of the gripper 5, whereupon the gripper 4 is locked by freeing the latches 58, the coilers 8 raised, and stretching effected by the hydraulic gripper 5. This gripper has a return cam which may be under constant pressure in which case a single-acting hydraulic valve is used, or both cams may be operated by a double acting valve. When stretching has been effected the gripper 5 is released the rollers 8 lowered and the free end of the strip drawn back by the gripper beyond the roller 8<SP>1</SP>, For heavy gauge material the roll 8<SP>1</SP> is then raised whereupon the coiler and gripper 4 are reversed to effect recoiling. When using the drum 3 the free end of the strip is connected to the drum which is driven together with the gripper 4 to effect recoiling. If desired the gripper 4 may be pulled back by the coiler instead of driven positively. The gripper may be driven by a heavy link chain which will withstand the stretching load so as to avoid the use of a notched bed.