Patent GB-971236-A (GB)
Title: Control for periodically operating shears for cutting travelling products
IPC: B21B37/70
Filed: 1962-11-12
Abstract: 971,236. Shearing; making ingots. F. MOELLER, and K. NEUMANN, [trading as VERWALTUNGSGESELLSCHAFT MOELLER & NEUMANN o.H. G.]. Nov. 12, 1962 [Nov. 13, 1961], No. 42634/62. Headings B3A nd B3W. A control apparatus for periodically operating a flying shear comprises two spaced photo-cells defining a gauge unit length which is a simple fraction of the length to be cut, an impulse generator driven from the material, a first counter which is started when the leading end of the material passes the first photo-cell and is stopped when the leading end passes the second photo-cell, a second counter which starts simultaneously with the stopping of the first counter, when an equal number of impulses are recorded in each counter and restores the second counter to zero, so that the number of gauge unit signals represents the length of material passed and a third counter for the gauge unit signals to emit a shears starting signal after a predetermined number of gauge unit signals have been received. The two photo-cells 3 and 4, spaced apart a distance c are arranged between rolls 1 and a rotating flying shear 10. The distance c is the gauge unit length and is a simple fraction of the length to be cut L and also of the distance y between the second photocell and the shear. There is an impulse generator 2, a first counter 5, a second counter 7, a comparator 6, and a third counter 8 which controls the shear motor 11. The length to be cut L = n 1  x c (where c is the gauge unit length) and the value n 1  is set in a device 13. The length y=n 2  x c and the value n 2  is set in the device 12. There is also a device 9 which cancels the stored value in the counter 5 when the trailing end of a bar passes the photo-cells 3 and 4. Operation.-When material 1a passes between the rolls 1, impulses are produced by the generator 2 and when the leading end of the material reaches the photo-cell 3 the counter 5 is started and continues to count until the material reaches the photo-cell 4, at which time the first counter 5 stops and the second counter 7 starts. When the count in the counter 7 is equal to the stored count in the counter 5, a comparator 6 produces a gauge unit signal which is passed to a third counter 8. This counter emits a shears starting signal when a predetermined number of gauge unit signals have been received. In the embodiment described, the length L is seven times the distance c so that n 1  = 7 and the length y is twice the distance c so that n 2  = 2. A pre-set device 12 deducts two from the first set of gauge unit signals received by the counter 8, to allow for the distance between the photo-cell 4 and the shears, and thereafter the shears operate every time the counter 8 has received seven signals. The length cut is determined by pre-setting a device 13 connected to the counter 8. In a modification, the gauge section defined by the photocells is positioned after the shears, and the device 12 is arranged to modify the count stored in the counter 8 so that the shears operate for fewer gauge unit signals for the first cut than for subsequent cuts. With this arrangement the accuracy of the cut lengths may be improved by taking advantage of the fact that the conveyer rolls beyond the shears rotate faster than the speed corresponding to the rolling speed and successive bars are spaced farther apart than the gauge section length so that a cancellation signal corresponding to the "endof-bar " signal is produced after each cutand each cut length is there by individually gauged.