Patent GB-906608-A (GB)
IPC: B65H19/18
Abstract: 906,608. Feeding webs. MIEHLE-GOSSDEXTER Inc. Nov. 2, 1959, No..37122/59. Class 100 (1). In a web supply apparatus, the web splicing apparatus is prepared for splicing when the expiring roll 14A reaches a first predetermined diameter and is subsequently rendered operative to effect splicing of the web W from the roll 14A to a web from a replacement roll 14B when the roll 14A reaches a second predetermined diameter. Sensing roll diameters.-A capacitor C, Fig. 7, is in series with resistances R1, R1a across a D.C. voltage source E. Contacts CP1A, CP2A, Figs 1 and 7, are opened and closed, once per revolution of a cam CA, Fig. 1, thus providing a diminishing interval of time between the opening of contacts CP1A and closing of contacts CP2A which depends on the increasing angular velocity of the roll 14A. When the expiring roll 14A is reduced to a first predetermined diameter, the time interval is such that the decaying voltages e v , Fig. 7, across the resistances R1 and R1a, during charging of the condenser C, exceeds a voltage e va  across a potentiometer 110, the switch CP1A being open and the switch CP2A being closed. The potentiometer 110 is connected to a tachometer generator 16 driven at a speed related to the linear speed of the web being fed to a printing-machine 11, Fig. 1. Thus, the voltage e va . Fig. 7, is related to the linear speed of web. When the voltage e v  exceeds e va  a diode 110 permits current flow through a relay coil MP, controlling contacts which initiate preliminary web splicing operations. Contacts MPa are closed to energize a relay X. Normally closed relay contacts X2 are opened to disconnect a slider 110a, while a slider 111a is connected in its place by closure of relay contacts X3. Relay contacts X4 close to shunt resistance R1a contacts X5 open to isolate capacitor C, and contacts X6 close to switch in resistance R2 and condenser C1. Thus, the circuit shown in Fig. 7 is modified to produce a more gradual decaying voltage E R  1  across the resistance R1 during charging of the condenser C1 upon opening of contacts CP1A. When the diameter reaches a second predetermined diameter, the interval between opening contacts CP1A and closure of contacts CP2A is such that the voltage E P1  exceeds the voltage e vb  across the potentiometer 110. The diode 101 again permits energization of relay coil MP. The apparatus may also be used in a web winding apparatus for indicating when the roll being wound has increased to a predetermined value. Controlling web tension and accelerating replacement roll.-The running tension of the web W, Fig. 1, is controlled by roll-engaging straps 18 under the control of a floating roller 25 in the same manner as that described in Specification 743,351. Transition tension of the web from the replacement roll 14B is controlled immediately after a splicing operation by an endless belt 60 of a predrive carriage 55 in the same manner as that described in Specification 826,647, the belts also serving to accelerate the roll 14B prior to a splicing operation to match the linear speed of the web W as described in that Specification. Web splicing and cutting apparatus.-A pivotally movable carriage 76 carries a plurality of splicing brushes 84 on a shaft 85 for deflecting the expiring web against the replacement roll 14B and a plurality of serrated knives 90 on a rotatable shaft 91. The carriage 76 is actuated between an operative lowered position and a non-operative raised position by a doubleacting pneumatic ram 79 controlled by a solenoid-operated valve 81. The shaft 85 is held cocked against the action of torsion springs, not shown, by a latch released by a solenoid BSOL. The shaft 91 is latched and released in the same manner by a solenoid KSOL. Operation of splicing apparatus.-Closure of the relay contacts MP1, Fig. 9 (not shown), upon energization of the relay MP, Fig. 7, when the first predetermined diameter is reached operates an audible signal device, not shown, giving a warning of an impending splicing operation. Closure of relay contacts MP, Fig. 9 (not shown), also energizes relays which cause closure of contacts for a motor M, Fig. 1, which drives a shaft 41 carrying roll spiders 42. When the new roll 14B reaches a predrive position, as detected by a light beam of a photoelectric device operating in the same manner as that described in Specification 826,647, a relay, not shown, is de-energized. Consequently, contacts to the motor M open and a faster carriage solenoid PASOL is energized to operate the valve 81 to cause lowering of the carriage 76. The lowering of the carriage 76 causes a limit switch 1CLS to open to energize the prederive solenoid PRSOL which actuates a valve 71 to effect lowering of the carriage 55. The new roll 14B is then accelerated by the belts 60, such that its peripheral speed matches that of linear speed of the web W. When the second predetermined diameter is attained the relay MP is again energized as previously described, thus initiating the energization of the brush solenoid BSOL which releases the brush 84 and subsequently permitting the energization of the knife solenoid KSOL which releases the knife 90 to cut the expiring end of web W. The relay MP and solenoid PASOL are de-energized, thereby causing retraction of the faster carriage 75 which in retracting cause contacts 2CLSa to open and contacts 2CLSb to close. The motor M is then energized to rotate the spider 42 carrying the roll 14B to rotate clockwise to position the roll 14B in contact with braking straps 18. A limit switch RLS2, Fig. 2 (not shown), opens to initiate de-energization of the solenoid PRSOL, Fig. 1, thereby actuating valve 71 to cause raising of the carriage 55.