Patent GB-971888-A (GB)
IPC: B31C3/00
Abstract: 971,888. Making tubes. R. C. CAN CO. Nov. 1, 1960 [Feb. 25, 1960], No. 37575/60. Heading F2P. [Also in Division B5] Apparatus for continuously preparing individual lengths of helically wound tubes of paper, fibreboard &c. having register indicia uniformly spaced along an outer surface thereof comprises a winding station and a cut-off station, said winding station including an axially extending mandrel with means for winding strip material axially along the mandrel at a predetermined speed, said cut-off station including cut-off means adjacent the mandrel for movement along a track parallel to the axis of the mandrel for severing the wound strip material at a predetermined location longitudinally thereof, and control means for said cut-off means including a target detector, a register detector and actuating means for moving the cut-off means along the track, said target detector comprising a photo-sensitive device positioned to view an area adjacent the axis of the mandrel and arranged to respond to the presence of tubing in that area, said register detector comprising a photo-sensitive device positioned to view the surface of said helically wound strip material and responsive to the presence of register indicia at a predetermined location axially of the mandrel, and electric circuit means for energizing said actuating means upon the coincident response of said target detector and said register detector. Three layers of strip are wound on the mandrel 19, an inner layer from a supply roll 22, a middle layer from a supply roll 21 and an outer layer from a supply roll 23, Fig. 2. The mandrel is rotated by a belt 18, driven by pulleys 16, 17 and passing over and around the mandrel which is surrounded at that point by helically wound strip, the belt 18 therefore providing a driving force for traversing the various segments of the wound strip along the mandrel. Glue is applied to the strip 21a, from the roll 21, by a drum 30 dipping into a reservoir 29. Similarly, glue is applied to the strip 23a, from the roll 23, at 34. The strip 21a is guided on to the mandrel by a roller 35 and the strip 23a is similarly guided by a guide blade 36. The inner layer is wound with an overlap, the middle layer is butt-jointed, the joints being out of register with those in the inner layer, and the outer layer is overlapped by an amount related to the register indicia, which are reflective spots, on the outer surface of the outer layer. The tube formed on the mandrel by the wound strips is cut at intervals by a circular saw 38, on a shaft 39, which is brought into engagement with the tube by a double-acting pneumatic cylinder 60 operating bell-cranks 44, 45 between which the shaft 39 is held, Figs. 3 and 4. To allow for the longitudinal movement of the wound tube the shaft 39 is moved longitudinally by a double-acting hydraulic cylinder 55 which propels the shaft 46 on which the bell-cranks 44, 45 are mounted. A " target control " 67, movable lengthwise of the mandrel by a screw-threaded shaft 68 operated by a hand wheel 72, carries a light source 76 and a photo-electric cell 76c, on opposite sides and facing one another. As the helically wound tube moves longitudinally it interrupts the light beam and the consequent change in potential, due to the photo-electric cell being no longer activated, causes a thyratron 76b, Fig. 10, to fire, so rendering operative the coil of a relay 77, whose contacts 77a, 77b close contact 77b, through a relay 78, energizes a time delay circuit, Fig. 11, which includes a capacitor 92, with a time constant determined in association with a resistor 93. The contact 94b, which closes after the time delay, is in parallel with a contact 87a in the register control and thus, if irregularity occurs in the operation of the register control, the time delay circuit starts the saw at a predetermined time after the detection of material by the target control, so minimizing waste of material. The time delay circuit operates with direct current supplied through a rectifier 95 and the time interval is adjusted by a potentiometer 96. The register control is indicated at 80, Fig. 3, and includes a combined light source and photo-electric cell, which is positioned according to the number of tubes required to be cut from the helical winding. When a reflective spot on the outside of the helical winding passes through the path of light, the conductivity of the photo-electric cell is momentarily increased. This change of conductivity is directed to the grid 85a of a twin triode 85, Fig. 9. The resulting signal is directed to the grid 86a of a double triode 86, the output of which is consequently unbalanced and renders operative the coil of a relay 87. Thus the cut-off operation takes place at a desired point after a certain predetermined number of tubes have been wound on the mandrel. With contacts 77a, 87a closed, Fig. 8, manual switches 89, 89a closed and sensing switches 90, 91 positioned at the rest position of the saw, the saw start solenoid 88 is energized; this condition being shown by a pilot light 88a. The saw starts on its longitudinal traverse at a speed which is co-ordinated with the longitudinal movement of the helically wound tube. When the saw has traversed a certain distance it operates a limit switch 114 and the sawtransverse-in solenoid causes air to be admitted to the cylinder 60 to cause its operation to bring the circular saw into contact with the tube, which it severs. When the saw has traversed further it operates a limit switch 115, causing the saw-transverse-out solenoid to return the saw to rest position. Upon a still further traverse of the saw, the saw-return switch 116 is closed and energizes the sawreturn solenoid, which causes the hydraulic cylinder 55 to return the saw to the start of its traverse. The switches 90, 91 prevent pulses of current from stray cycles from passing through the saw-start solenoid at irregular times.