Patent GB-484756-A (GB)
Title: Doctor-blade constructions for gravure printing-presses
IPC: B41F9/10
Filed: 1937-05-06
Abstract: 484,756. Sharpening machine-cutters. FEENY, V. F. (Miehle Printing Press & Manufacturing Co.) May 6, 1937, No. 12956. [Class 60] [Also in Group XVI] In a doctor-blade device for gravure printing- presses the doctor-blade is formed as an endless band travelling around driving or guiding pulleys, with one stretch thereof scraping the excess ink from the printing-element, and the inactive stretch on the opposite side of the pulleys is treated by sharpening-means, such as grinding and honing discs or files, and wiping-means, whereby the doctor-blade is reconditioned. One embodiment of the device is shown in plan in the two half-views in Figs. 1 and 2, and in part sectional elevation in Fig. 6. The device comprises a main supporting shaft 11, oscillatable in bearings 12, 13, adapted to carry by means of brackets 14 a long supporting plate 15 which carries the whole of the mechanism for the device. The doctor-blade band 18 is mounted on two pulleys 16, 17 both driven through wormgearing from a shaft 23 operated from a motor 25 fixed to the shaft 11, and means is provided whereby the pulley 17 can be adjusted to tighten the doctor-band, and also to tilt slightly the band to ensure that the back edge of the band rests in the bottom of grooves in guide blocks therefor. The various grinding and honing wheels to be described later are also geared to the shaft 23. The blade edge of the doctor-band 18 is pressed into contact with the printing-cylinder 19, Fig. 6, by a resilient steel strip 51 supported in a plate 48 secured to a recessed bar 42 on the main plate 15, adjusting-screws 52 being provided for regulating the pressure of the strip on the doctor-band. Pressing beneath the doctorband edge is an ink-deflecting strip 43 also mounted on the bar 42. The back edge of the doctor-band slides in grooves in a number of pairs of guide blocks 53, 63, each pair of blocks being secured to screws attached to worm-gears which are engaged by worms on a stub shaft 58 operable by means of a knob 59 to adjust the distance of the doctor-band from the cylinder 19 during operation of the doctor-band. The whole device can be moved away from the cylinder 19 by rocking the shaft 11. This is effected by rotating a handwheel 141 which operates a toothed rack 142 in mesh with a toothed sector fixed to the shaft 11. The doctor-band travels in the direction of the arrows A, any remaining ink thereon being removed by a scraper 66 before the band passes around the pulley 16. The band then passes through a slit piece of wiping-leather 71 in a bracket 72, a slit piece of felt 73 moistened with kerosene on a bracket 74, and then to the first grinding-appliance. This comprises a grinding-wheel 78 mounted on a shaft having axial movement and spring-pressed to force the wheel against the edge of the doctor-band. An adjustable bracket-plate provided with a fibre block supports the band during grinding. The doctor-band may pass to a finer grinding or honing-wheel 104 mounted and driven in the same manner as the wheel 78, and engaging the same side of the band. The burr on the opposite side of the band is now removed by passing the band past a further honing-wheel 105. The band is held against the flat face of the wheel 105 by a fibre block on an adjustable bracket, and the wheel is spring-pressed into engagement with the band. The doctorband now passes between a pair of obliquelyarranged resilient wiping and guiding blades 127, 128, then through another slit wiping leather 131, and finally between two pieces of felt 134 soaked in petrol. The grinding and honing discs acting on the bevel or the flat rear surface of the doctor-band may be inclined relative to the band.