Patent GB-691243-A (GB)
Title: Improvements in rotogravure impression mechanism
IPC: B41F13/38
Filed: 1949-05-20
Abstract: 691,243. Printing-machines. HOE & CRABTREE, Ltd., R. May 20, 1949 [May 29, 1948], No. 13583/49. Class 100(ii) Cylinder-tripping mechanism. -Impression mechanism for a rotary intaglio printing unit comprises pressure, impression and printing cylinders and drive means to lower the pressure cylinder into co-operation with the impression cylinder to produce the required pressure co-operation with the printing- cylinder, there being provided control means responsive to the position of the pressure cylinder and regulating the drive means to cause the pressure cylinder to be lowered rapidly to a predetermined position and then slowly to the final printing position. The printing cylinder 5 is journaled in bearings in frames 1, 2, Figs. 2 and 3. The pressure cylinder 7 is journaled in bearings in vertical slide members 9, 10. The impression cylinder 6 is journaled in bearings on arms 75 pivoted on stub shafts 76 on the slides 9, 10, the arm 75 having gear segments 77 engaging gear segments 78 fixed to an equalizer shaft 79 to maintain parallelism of the cylinder 6, which by pivoting of the arms 75 about the stubs 76 is separable from the cylinder 6 by a small amount limited by an arm 81 fixed to the shaft 79 and having a rotatable stub shaft 83 threaded to receive a shaft 85 adjustable by a hand-wheel 89. A compression spring 88 allows the cylinder 5 to contact the cylinder 6 when in printing position. The slides 9, 10 are raised and lowered for tripping and adjusting printing pressure by a reversible electric motor 19, Fig. 7, acting through shaft 18, worm gearing, and threaded rods 11, 12, to which are secured housing caps 25, 25<SP>1</SP>. Telescoping spring housings comprise the upper portions or caps 25, 25<SP>1</SP> and lower portions constituting the upper parts of the slides 9, 10 and carrying rings 34 and having shoulders 32. Threaded to the rods 11, 12 are sleeves 26 having round them compression springs 27 and upper and lower thrust washers 28, 29 adapted to abut the springs and also the rings 34 and shoulders 32 respectively. In the normal position of the sleeves 26 the printing pressure comprises the weight of the cylinders 6, 7 and associated parts, but this pressure can be increased or decreased at either or both ends of the cylinders by rotating handwheels 37, 45 to lower or raise the sleeves 26 and cause the springs 27 to exert pressure downwards on the shoulders 32 or upwards on the rings 34. The wheels 37, 45 may be connected or disconnected from each other by a catch 47. The wheels also actuate pointers to indicate the positions of the sleeves 26. An arm 80 rotatable on the shaft 79 is adjustable by a screw 84 abutting the end of the shaft 85, and has a shoulder 90 abutting a rod 91 slidably supported on the' slide 10. Four switches S<SP>1</SP>, S<SP>2</SP>, S<SP>3</SP> and S<SP>4</SP> are secured in a control housing 70 fixed to the slide 10. The rods 11, 12 are lowered rapidly towards printing position until the rod 91 raises the two-way switch S<SP>1</SP>, when the downward movement continues slowly with a jogging movement. When the spring housings are telescoped to a predetermined amount a rod 96 secured to the cover 251 opens the switch S<SP>4</SP> to stop the motor. A rod 93 slidably mounted on the slide 10, abutting a stop 94 on the frame 2, and acting to open the switch S<SP>2</SP> in the lowermost position of the slides, acts as an emergency stopping device. When the spring housings are expanded to a predetermined amount, a rod 95 secured to the cover releases the two-way switch S<SP>3</SP> and the rods 9, 10 are raised slowly and with a jogging action, so that the amount of telescoping of the housings is controlled within small predetermined limits by the switches S<SP>3</SP>, S<SP>4</SP>, thus maintaining constant printing pressure regardless of variations, such as in the thickness of the web. When the rods 11, 12 are raised rapidly for tripping a further switch S<SP>5</SP> is automatically opened to stop the motor in the uppermost position of the cylinders. For lowering to printing position, a button 101 is pressed, and current passes from supply L<SP>1</SP> through switches S<SP>1</SP>, S<SP>4</SP>, S<SP>2</SP> lower contacts of a relay R<SP>1</SP> and the down winding 111 of motor relay M to supply L<SP>2</SP>. Alternatively, this circuit can be made by pressing a master button 103 at the folder. The relay M then closes its down contacts, and current passes from supply L<SP>1</SP> to line 114 and motor 19 and from supply L<SP>2</SP> to line 115 and motor 19. The motor 19 is connected to the supply L<SP>3</SP>. When the switch S<SP>1</SP> of any unit is raised by rod 91, the relay circuit is broken, and current is supplied from supply L<SP>1</SP> through contacts 160 intermittently closed by a cam 162 driven by a continuously rotating jogging motor 104, jogging line L<SP>6</SP>, switches S<SP>1</SP>, S<SP>4</SP>, S<SP>2</SP>, relay contacts and winding 111 to supply L<SP>2</SP>, the motor thus being driven intermittently until switch S<SP>4</SP> is opened by rod 96. For raising the cylinders, a button 100 or a master button 102 at the folder, is pressed, and current passes from supply L<SP>1</SP> through switch S<SP>5</SP> and relay R to-supply L<SP>2</SP>. Relay R thus energized, opens its lower and closes its upper contacts, and current passes-from switch S<SP>5</SP> through the upper contacts and the up winding 133 of relay M to supply L<SP>2</SP>. A parallel circuit from switch S<SP>5</SP> to winding 133 also exists through switch S<SP>3</SP>. The relay M then closes its upper contacts, and current passes from supply L<SP>1</SP> to line 115 and motor 19 and from supply L<SP>2</SP> to line 114 and motor 19. The motor is stopped when switch S<SP>5</SP> is opened. When the switch S<SP>3</SP> of a unit is lowered by rod 95, current passes from supply L<SP>1</SP> through contacts 163 intermittently closed by a cam 164, jogging line L<SP>7</SP>, switch S<SP>3</SP>, and up winding 133 to supply L<SP>2</SP>, so that the motor 19 is driven intermittently. The motor can also be driven rapidly to raise the cylinders in an emergency by pressing a "red button stop " operating contacts 170 to by-pass contacts 163. A normally open relay 141 is provided, which may be closed to raise the impressions of all the units, when the drive clutches of the web feeding rollers are opened. The jogging lines L<SP>6</SP>, L<SP>7</SP> are connected in parallel through the switches S<SP>4</SP>, S<SP>3</SP> of each unit, so that the jogging drive can be cut in for independent units by actuation of their individual switches S<SP>3</SP>, S<SP>4</SP>.