Patent GB-742822-A (GB)
Title: Improvements in or relating to cutting machines
Inventor: DAVIS ROBERT
IPC: D06H7/02
Filed: 1953-10-15
Abstract: 742,822. Cutting-machines. REED & CO., Ltd., A. E. Oct. 15, 1954 [Oct. 15, 1953], No. 28499/53. Class 31 (1). A machine employing rotary knives 3 for cutting a continuously - fed web 2 into lengths is provided with a drive mechanism between the knives and the means 1 for feeding the web comprising a differential gear 26 which through two of its connections conveys the drive to or from a gear-box 10 affording positive drive at two or more velocity ratios and has its third connection coupled through a variable gear 29 coupled directly or indirectly to one of the first two connections, the two gears 10, 29 thereby permitting continuous variation in the velocity ratio between the knives and feed means and therefore the cutting of the webs into accurate lengths. The gear-box 10 is shown as having its input shaft 9 driven from a motor through bevel gears 7 and comprises (a) two gears 11 fast on the shaft 9 for driving a layshaft 13 through either of two gears 12 as determined by a clutch 14 on the latter shaft, and (b) two further gears 20 on the layshaft for driving an output shaft 18 through either of two gears 19 as determined by a clutch 20 on the layshaft. The output shaft 18 is connected to one shaft 25 of the differential gear 26, the other shaft 27 of which drives the web-feeding rolls 1 through bevel gears 8 ; the casing of the differential gear is connected by a chain drive 28 to the continuously-variable gear 29 which is driven by a chain 30 from a sprocket 31 on either the layshaft 13 or output shaft 28 on the gear-box 10. In the form shown, the motor driving the input shaft 9 of the gear-box 10 also drives the cutter rolls 3 through variable-speed gearing 6, such as elliptical gearing or a four-bar kinetic chain, to ensure that the speed of the knives at the actual point of cutting is the same as that of the web. The gear-box 10 provides for drive at any of four velocity ratios and it is stated to be advantageous to select the gear ratios so that when the machine is set to cut comparatively short lengths the unit 29 takes a smaller part of the load than it does when the machine is set to cut longer lengths. The two sections of the gear-box 10 and the gear 29 are controlled by handles 16, 22, 32, the handle 32 for the gear 29 being coupled to a pointer 33 movable over a dial 34 which is provided with four scales each calibrated to read directly the cut-off lengths corresponding to one of the four gear ratios of the gear-box 10. Instead of connecting the drive motor to the cutting knives, it may be connected to the feed means or at an intermediate point in the transmission ; usually, however, it is connected at the end of the mechanism where the greater power is required. In further modifications : (a) the gear-box 10 is of epicyclic type, (b) separate drive motors may be provided for the knives and feed mechanism, the above-described mechanism then being interconnected between the knives and feed mechanism so that while it transmits only a relatively small proportion of the drive it serves to correlate the speeds of the knives and feed rolls, and (c) two of the drive mechanisms are arranged to connect two sets of cutting knives to a common feed mechanism whereby a sheet previously cut into two strips may be cut into the same or different lengths according to the setting of the two mechanisms.