GB1257447A - - Google Patents

Abstract

1,257,447. Feeding sheets. NORTH AMERICAN ROCKWELL CORP. 15 Oct., 1970 27 Oct., 1969], No. 48956/70. Heading B8R. In order to compensate for misregister in machines such as multi-colour sheet printing machines due to "fan out" or change in lateral dimension of the trailing part of a sheet caused possibly by absorption of moisture or by anironing effect as the sheet passes through the machine, the grippers carrying a sheet from a feed table to an impression cylinder are operated so that as they start their feed movement, they cause a bowing of the front edge of' the sheet which in turn causes the side edges of the sheet adjacent to the trailing part to be moved towards or away from one another to restore the sheet width at the trailing part toits normal dimension. As shown in Figs. 5, 7 an oscillating shaft 31 carries the gripper structure which comprises a number of pivoted arms 73 with camcontrolled gripper fingers 61 each adapted to engage the roughened surface 57 of a gripper pad 51, after the sheet 15 has been registered against a front stop 13 on a table 11. The pads 51 are attached to a resilient transverse bar 50 which is attached to the arms 73 by bolts 101 with a certain amount of play. For this purpose, square sleeves 104, Fig. 5, slightly longer than the bar thickness are mounted on the bolts 101 and are pressed against the arm 73 by washers 102 on the bolts, and springs 107 press the bar 50 against the washers 102. A fixed member 125, Fig. 3, carries three stops 121 which can be adjusted by screwed spindles 132 so that as the grippers approach the sheet-receiving position, they abut against surfaces 136 on the bar 50 situated between the pads 51, one stop being centrally of the bar 50 and the other two near its ends. The stops 121 cause bowing of the bar 50 at the sheet-receiving position, but as the grippers start their feed movement, the bar 50 being separated from the stops reverts to its normal straight condition thus causing bowing of the front edge of the sheet with resulting alteration of the width of the sheet at its trailing edge. The stops may be set to cause increase or decrease of the width at the trailing edge according to requirements.