Patent GB-675911-A (GB)
Title: Sheet separator in the feeding of sheets, particularly corrugated sheets, to machines
Inventor: JULIEN ANDRE
IPC: B65H1/06
Filed: 1950-08-08
Abstract: 675,911. Feeding sheets. SOC. CENTRALE DES USINES A PAPIERS CENPA. Aug. 8, 1950, No. 19737/50. Class 100 (i). [Also in Groups VIII and XL (b)] Pile tables; sheet-separators.-In apparatus for separating flat elements from a stack by means of a moving friction belt, a presser member arranged above the stack is controlled by an element just separated from the stack to apply pressure on the stack during the separation of the element immediately following, and to cause the presser member to be raised after a predetermined number of elements have been separated from the stack to allow an equivalent number of elements to be moved on to the stack below the presser member. As described, the control is exercised by combined photo-electric and mechanical means, and the sheet-separator forms part of a machine (see Group VIII) for manufacturing continuous lengths of single or double-sheet corrugated cardboard. The elements E, Figs. 1 and 6, in the stack P comprise a corrugated sheet 4 on which is gummed a flat sheet 3. The stack rests on a number of parallel rubber &c. belts 30, supported by a table 31, passing around pulleys 13, 14, the pulleys 14 being driven continuously from a motor shaft 15 through a variable-speed gear 20. The front wall 32 of the stack is adjustable vertically by a screw 33 to form a throat between the lower edge of the wall and the belts for the passage of one element E, and a slide 39 on the wall 32, normally pressed downwardly by a spring 44, is adapted to be raised a variable amount, to allow an element to be separated, by fingers 41 which engage a roller abutment 43 on the slide. The fingers 41 are secured to a spindle 42 adapted to be rocked by an electromagnet 89 acting through a rod 88 and lever 86. The electromagnet 89 is controlled by a photoelectric device 66, 67, described below, and is also used to oscillate a lever 83 carrying a pawl 81 which rotates intermittently a ratchet-wheel 79 to which is secured a cam 78 having a projection 77 adapted to complete an electric circuit at 76 when a predetermined number of elements E have been separated from the stack P. A presser bar 47 is attached to the lower end of a piston rod 48, the piston 49 of which is disposed in a cylinder 50 provided with two inlets 53, 54 and two outlets 56, 57 for the pressure fluid. These inlets and outlets have valves 58-61 operated by electromagnets 62-65 controlled by the photoelectric device 66, 67. The photo-electric device comprises 'a light source 67, Fig. 4, which projects a beam of light on to successive separated elements E which reflect the beam on to a photo-electric cell 66. Each element has a small dark area 68 (not shown) thereon which momentarily diminishes the intensity of the reflected light, whereby the electromagnets 62-65, and 89, are operated, respectively, to cause pressure to be applied to the presser bar 47, and to step forward the ratchetwheel 79. In a modification (Fig. 15, not shown) the light and cell are arranged beneath the stack P, and the dark area is the shadow cast on one element by the edge of the preceding element. The bar 47 presses on the stack just before the rear edge of the element E' being separated has left the stack, and ensures that the next element E<SP>2</SP> is flat on the belts and is separated from the stack in abutting relationship with the element E<SP>1</SP>. Each element is fed by the belts 30 to feed rollers 70, 71. When a predetermined number of elements E have been separated from the stack i.e. when the ratchet-wheel 79 has caused the cam 78 to close the switch 76, electromagnets 103, 105, Figs. 1 and 4, controlling valves 102, 104 in the fluid inlet and outlet, respectively, of a piston and cylinder device 100, 101, cause the piston 100, through a system of levers 95-99, to move a pusher bar 90 to the.right, Fig. 1. The valves 58-61 controlling the presser bar 47 are also electromagnetically operated so that the bar 47 is raised, and the pusher 90 moves a number of fresh elements P' over the stack to replace those separated. A spring 91 returns the pusher 90. The elements P<SP>1</SP> are placed in the position shown in Fig. 1 either manually or by known automatic means. In a modification (Fig. 14, not shown) where the elements E are to be separated from the stack in spaced, instead of abutting, relationship, the separating belts 30 are raised and lowered intermittently. The bearings of the belt pulleys 13, 14 are slidably mounted and supported on cams which are oscillated simultaneously, through levers, by a fluid-operated piston in a cylinder having fluid inlets and outlets controlled by electromagnets arranged in the circuit of the photoelectric cell 66. The photo-electric cell 66, Fig. 4, governs the excitation of the electromagnets 62, 64, 89 through a power relay R<SP>1</SP>, reversing switch I, and time relay R<SP>2</SP>, the magnet 89 being in parallel with the magnet 62. The switch I is controlled by the relay R' which comprises a transformer 113, 116 which feeds a coil 115, through a rectifier 114, to control the blade 111 of the switch. The coil 116 is joined to the A.C. mains 106, 107 through the relay R<SP>2</SP>. When the anode 120 of the cell 66 is normally illuminated, the circuit of the primary coil 116 of the relay R' is cut, but is completed when a dark area 68, Fig. 2 (not shown), on an element E passes beneath the light beam 67. The time relay R<SP>2</SP>, Fig. 5, comprises an amplifier 121, a thyratron 122, and a time valve 123; the auxiliary grids of the valves 121, 123 are not shown. The lines 125, 126 from the mains feed the primary of a transformer 124, the secondaries 127, 131 of which supply the filaments 129, 130, 132 of valves 121, 122, 123 and current for the light 67, and the secondaries 133, 134 providing in combination with a rectifier 135 and a filter 137, a high voltage current in the circuit 136. The grid 138 of the amplifier 121 is connected to the cell 66, the cathode 143 is biassed by resistance 144 and condenser 145 in parallel, and the anode 146 is connected to the grid 149 of the thyratron 122. The cathode 150 of the valve 122 is biassed by resistance 151, and the anode 152 is connected through a'reversing switch II and potentiometer 157, 158, which is regulated by the variable-speed gear 20, Fig. 1, to the grid 155 of the time valve 123. The moving blade 156 of the switch II is also connected through.the coil 159 of a make-and-break device C to the cathode 150 of valve 122, and to a point S, which is connected to the cathode 162 of valve 123, and to the grid 155 of the valve 123 by way of a condenser 164. The device C is connected by lines 117, 118 to the power relay R'. The blade 156 is actuated by a coil 167 in the circuit of the anode 168 of the time valve 123. The anode 120 of the photoelectric cell 66 is connected by the line 169 to the point S. When a dark area 68 of an element E reduces the intensity of illumination on the anode 120 of the cell 66, the voltage on the control grid 138 of the valve 121 is varied to such an extent that the thyratron 122 discharges by way of the coil 159 which closes the make-and-break C, and closes the primary circuit of the lines 117, 118 of the power relay R'. The grid 155 of the valve 123 is instantly biassed, suppressing any current in the anode of this valve, so that the coil 167 allows the blade 156 of the switch II to contact the tongue 154. The condenser 164 is charged slowly by way of the potentiometer 157, 158 before the switch is reversed, and then discharges rapidly by way of the coil 159, short-circuiting the potentiometer 157, 158, this discharge being too weak to again close the device C. The power relay R' circuit, closed by the discharge of the thyratron 122, interrupts, by way of the reversing switch I, the excitation of the magnet 64 and completes the circuit of the magnets 62, 89, whereby the valve 58 is opened, and the valve 60 closed. The electromagnets 63, 65, 103, 105 are controlled by a reversing switch III governed by the coil 176 of an auxiliary time relay R<SP>3</SP>. Normally, the relay is not energised, the blade 175 of the switch III contacts the tongue 173, the valves 61, 104 are open, and the valves 59, 102 are closed. These positions are reversed on excitation of the relay by the closing of the switch 76. The relay includes a dry rectifier 177, and a reversing switch IV. When switch 76 is closed, an electromagnet reverses the switch IV, a condenser 179 is discharged through the coil 176 for a time regulated by a resistance 185 and potentiometer 186. During this period of discharge, the switch III is reversed as also the position of the valves 59, 61, 103, 104. Where separated elements E, Fig. 11, are to overlap a distance a, the sheets 3 are shorter by this amount. The throat between the wall 32 and the belt 30 is adjusted to permit the passage of two superposed elements, but the slide 39 only allows the passage of one element until it is raised by the fingers 41. The slide 39 is raised simultaneously with the application of pressure by the bar 47, whereupon two elements are separated which overlap by a distance a.