GB910230A - A printing press - Google Patents

Abstract

910,230. Printing-machines. HARRISINTERTYPE CORPORATION. Feb. 23, 1960 [March 2, 1959], No. 6305/60. Class 100 (2). Cylinder trips.-In a throw-on and throw-off mechanism for sheet-fed rotary offset printing- machines wherein the gaps of the cylinders are in registry with each other during a part of each rotation and one of the cylinders is movable between operative and inoperative positions, the retracting movement is initiated while the gaps are in registry at the printing line and the advance movement of the cylinder is initiated at a point in the rotation of the cylinders in advance of the point at which the throw-off movement is initiated and is completed after said point and before the trailing edges of the gap pass the printing line. The blanket cylinder 11 is thrown off the plate cylinder 10 by rotating an outer, eccentric 15 clockwise by moving upwardly along its length a shift bar 31, whereby through a bell-crank 32 and links 36, 37 a bracket 20 connected to the eccentric is shifted, the eccentric being adjustable by a turnbuckle connection 68 and the link 37. An inner eccentric 14 carries a bracket 18 connected to the bracket 20 by toggle links 22, 23, whereby the eccentric 14 rotates with the eccentric 15. The cylinder 11 is thrown off the impression cylinder 12 by rotating the eccentric 14 clockwise with respect to the eccentric 15, by moving a shift bar 30 downwardly along its length so as to move a toggle link 28 to the left. The pressure of the blanket cylinder against the impression cylinder is adjustable by rotating manually a shaft 136, which through an expansible drive 130, 126 and an arm 121 adjusts the relative position of the eccentrics. The bar 31 is moved upwards by a pin 47 engaging a notch in its left side, and downwards by a pin 48 engaging a notch 61 in its right side, while the bar 30 is similarly controlled by pins 72, 74. The pins are actuated by cams 46, 77 on the plate and impression cylinder shafts. The bar 31 is moved about its pivoted lower end into the path of either the pin 47 or the pin 48 by a rod 62 under manual control or under automatic control when a malfunction of the press is occurring. The bracket 20 is connected by a yieldable device 90 to the bar 30, so that when the eccentric 15 is moved to throw-off position, the bar 30 is moved into the path of the pin 72. The cylinders are provided with gaps 13. The arrangement is such that the cylinder 11 is first thrown off the cylinder 10 and then off the cylinder 12, and is also thrown on to first the cylinder 10 and then the cylinder 12. The cams are so constructed and mounted that the working strokes of the throw-on pins 48, 74 are initiated before the gaps have met and completed after the middle of the gaps have passed each other, while the working strokes of the throw-off pins 47, 72 are initiated after the gaps have met but before the middle of the gaps have passed each other and completed after the gaps have passed.