Patent GB-684947-A (GB)
Title: Improvements in cutting mechanism
IPC: B29D30/46
Filed: 1951-08-31
Abstract: 684,947. Cutting-machines. UNITED STATES RUBBER CO. Aug. 31. 1951. [Nov. 1, 1950] No. 20587/51 Class 31 (i). [Also in Groups XVI, XXX and XL (b)] Mechanism for cutting strips of definite width from a continuous length of tyre fabric comprises a conveyer 70, Figs. 1 and 2, for transporting the fabric to be cut, a carriage 24 which is disposed transversely of the conveyer for carrying a cutting device 23 and is mounted for adjustment parallel to the direction of travel of the fabric, sensing means 260, 261 spaced from the carriage in the direction of travel of the fabric and mounted independently of the carriage for detecting the presence of the fabric. When the latter has been conveyed to a definite point past the cutting device, control means interconnected between the sensing means and cutting device for actuating the latter, and means for making incremental adjustment in the position of the sensing means to vary incrementally the width of the cut piece without adjusting the position of the carriage. The fabric 21 is drawn from a verticallymovable roll 30 on a wheeled carriage 33 by two rollers 45, 46 driven by a two-speed motor 50 and then conveyed past the cutter assembly 23 on endless bands 70 which are also driven by the motor 50 but at slightly greater speed than are the rollers 45, 46 ; the fabric is brought at high speed to near the cutting position and then at slow speed until stopped in correct cutting position. An intervening cloth liner 31 which is wound up with the fabric 21 on the roll 30 is drawn from the latter on to a second vertically-movable roll 37 on the carriage 33. The cutter assembly 23 comprises a cutter beam 27 of built-up hollow form and a lower anvil beam 29 which are formed as a unit capable of being swung about a central vertical axis 25 on a wheeled carriage 24 movable longitudinally of the machine on guide rails 83. The anvil beam 29 is supported on the carriage 24 and its ends are connected by members 157, 158, Fig. 3, to a parallel lower beam 159 ; in order to accommodate the beam 29, each endless band 70 is diverted from its normal horizontal path into the U-formation shown in Fig. 6 by pulleys 131-134 on a frame 126 which is slidable on guides 125 on the carriage. The beam 27 is connected at its ends-by pivoted links 164, 166 to the end members 157, 158 of the anvil beam 29 and operated by doubleacting pneumatic cylinders 160, 161 which are pivoted to the latter beam and have their pistons connected to the links 166 ; the linkages 164, 166 on opposite sides are connected by cables 180 with interposed springs 181. The cylinders 160, 161 are controlled by an automatically-actuated valve control. Each cutting stroke of the beam comprises a sideways rocking motion, one stroke being to the left and the next to the right ; the dotted line position of the beam shown in Fig. 3 is that taken up at the beginning of one stroke, and the start of the next stroke it will be tilted in opposite direction. Towards the end of each stroke the appropriate one of two pins 182, 183 on the beam 29 causes the beam 27 to be tilted upwardly to permit a new length of fabric to pass to cutting position. The beam 27 is guided in its rocking motion by end rollers engaging the inner arcuate edges of plates 187 on the beam 29, and extensions on the beam 27 engage side faces of the plates to provide stability. The cutter blade 26, Fig. 6, may be a flexible, square-sectioned strip which is held by clips 146 in a recess 144 in the curved underface of the beam 27; and each of its corners is ground to provide a narrow flat surface 143 for cutting by a crushing or squeezing action against the anvil ; any of the corners of the strip may be used for cutting. The anvil beam 29 is recessed to receive the anvil proper 28, Fig. 6, which rotated in the direction of travel of the fabric when the latter is travelling at high speed by rack and pinion gearing 204, 205, Fig. 3, actuated through a one-way clutch by a doubleacting pneumatic cylinder 207 controlled by an automatically-actuated valve ; friction between the anvil 28 and beam 29 is relieved by mounting the bearings for the anvil on springs which urge the latter upwardly within limits provided by adjustable stops. The width of cut is adjusted by moving the carriage 24 along the rails 83 by hand-operated gearing 113, 114 acting upon a nut which is rotatable in the carriage and engages a fixed longitudinal screwed spindle 100. The angle of cut is adjusted by swinging the cutter and anvil beams 27, 29 about the axis 25 by screw-andnut gearing, the nut being pinned to the underside of the anvil beam 29 ; during this movement, the beam 29 contacts one or other of two projections 241, 242, Fig. 6, on each frame 126 so as to slide the latter appropriately on its guides 125. A fixed longitudinal scale 245, Fig. 2, co-operates with a pointer 249 on the carriage 24 for indicating width of cut, and a scale on the end of the carriage 24 co-operates with a pointer on the beam 29 to indicate angle of cut. Since for different angles of cut the adjustment of the carriage 24 for a desired width of cut will be different, a different width scale will be needed for every angle of cut; the scale 245 is therefore calibrated to show separate width scales for different cutting angles and the pointer 249 is automatically moved vertically to register with the appropriate width scale by being geared with the hand-operated mechanism for varying the angle of cut. The sensing means for controlling the automatic operation of the machine consists of two spaced photo-electric units 260, 261, Fig. 2, which are positioned above the path of travel of the fabric and operate switches in an electric control circuit for the motor 50 and solenoidactuated valves controlling the rotation of the anvil and operation of the cutter beam ; each unit 260, 261, together with its light source, co-operates with a mirror disposed beneath the path of the fabric. In operation, the motor 50 is first set so that the fabric moves forward at high speed until it is in a position to deenergize the first unit 260 and thereby cause (a) the motor to drive the fabric at low speed, and (b) de-energization of the solenoid valve controlling rotation of the anvil so as to stop the latter. When, with the fabric in correct cutting position, the second unit 261 is deenergized, the motor 50 is stopped and braked and one or other of two solenoids is actuated to set the control valve of the cylinders 160, 161 for movement of the beam 27 through a cutting stroke. The energizing circuit of the operative solenoid is through the contacts of a tune delay relay (which is energized when the unit 261 is de-energised) and one of two limit switches 196, 197, Fig. 2, which are provided at opposite ends of the anvil beam 29 and alternately closed by the beam 27 at the end of successive cutting strokes. Shortly after the beam 27 starts its cutting stroke, the time delay relay opens its contact to prevent immediate repetition of the cutting stroke. When the operator removes the cut length, the units 260, 261 are again operative to repeat the cycle. The units 260, 261 depend from a plate Figs. 11 and 12 (not shown) which can be moved longitudinally of the machine in definite increments so that the width of cut may be altered without adjusting the position of the carriage 24.