GB758719A - Improvements in or relating to control devices for apparatus for applying coatings to metal sheets - Google Patents

Abstract

<PICT:0758719/III/1> <PICT:0758719/III/2> A device for controlling the relative positions of the rollers of a pair of rollers in a machine for applying a coating of lacquer or other liquid to metal sheets which pass between the rollers, comprises a detector member movable in response to the passage thereover of a sheet, a slide member connected to be displaced under control of the detector member, a control member disposed to be engaged by the slide member in one of two positions thereof, a power source independent of the drive of the machine and operable under control of the control member, and levers connected to at least one of the rollers and disposed to be actuated by the power source so that when a sheet or a succession of sheets passes over the detector member the slide member contacts the control member in a first position to cause said rollers to be moved to a coating position, and when there is an interruption in the passage of sheets over the detector member the slide member contacts the control member in a second position to cause said rollers to be moved to a non-coating position. The sheets S (Fig. 5) being fed in timed relationship to the rollers 2, 3, pass over and depress from its normal position a detector finger 5, so shaped that it cannot rise while a normally spaced succession of sheets is passing, but is pivoted on a pin 6 fixed to the machine frame 1 so that the weight of the detector finger body 5a raises the finger if the succession of sheets is broken. Pivoted on a pin 17 attached to the frame 1 is a pawl 16 with an aperture 19. When the pawl is caused to oscillate about its pivot 17, the end 20 of the detector finger body 5a enters this aperture if the finger is in the raised position, but prevents the oscillation of the pawl if the finger is depressed. Two cams 8 and 39 are secured on a shaft 7, journalled in the machine frame and rotated by the drive of the machine in time with the rollers, and pivoted on this shaft is a slide block 31 carrying a slide 30. This slide carries at its end a yoke 41 with ends 44, 45, one or other of which can abut an arm of the double armed lever 48 pivoted on a shaft 49. The lever 48 controls the piston 53 of a valve 54 which admits compressed air, from an external source, to one side or other of a double-acting piston 55, which operates toggle levers 61, 62, to raise or lower the pressure roller 3. A triangular cam lever 10, pivoted on a pin 11 fixed to the frame 1, carries at one end a cam follower 9 which rolls on the cam 8, while the other end is connected by links 23-25 to a lever 26, secured on a rod 27 journalled in the frame 1. A cam follower 40 (Fig. 1) mounted on the slide 30 is held in contact with the cam 39 by a tension spring 36 acting on the slide. Also secured on the rod 27 are a lever 28, which is pivotally joined by a link 29 to the slide 30, and a further lever 32 connected to the machine frame by a tension spring 34, which holds the cam follower 9 in contact with the cam 8. When the detector finger is depressed the pawl 16 cannot oscillate, since its end engages the end of the detector finger body 5a, and it acts through the rod 12 and the cam lever 10 to hold the cam follower 9 at the peak of the cam 8 so that the cam follower cannot follow the cam as it rotates. In this case the slide 30 does not oscillate about the shaft 7 but continues to perform the reciprocating motion imparted by the cam 39. The end 44 of the yoke 41 then abuts the arm 46 of the lever 48 and turns it in an anti-clockwise direction, thus driving down the piston 53. Compressed air is thereby admitted to the righ-hand side of the piston 55 which then moves to the left and actuates toggle levers 61, 62, thus raising the roller 3 and closing the gap between the rollers. When the detector finger is raised, as when a sheet is absent or the spacing between sheets is abnormally large, the pawl 16 is free to oscillate, the end of the detector finger body 5a entering the aperture 19 in the pawl; consequently the cam follower 9 remains in contact with the cam 8 and the cam lever 10 transmits to the slide 30 oscillatory motion about the shaft 7. The cams 8 and 39 are so adjusted that the end 45 of the yoke 41 now abuts the arm 47 of the lever 48 and turns the latter in a clockwise direction, raising the piston 53 and causing the roller 3 to be lowered. Having moved, the doublearmed lever 48 will maintain the same position until the position of the detector finger 5 changes, for the slide 30 will continue to abut the same arm 46 or 47 with each rotation of the cams without being able to move it further.