Apparatus method for centering and aligning sheets

摘要

An apparatus and method for centering and aligning sheets. The apparatus includes a D-roller assembly for cyclically engaging and transporting sheets and a centering and aligning mechanism for centering the lining sheets which is synchronized with the operation of the D-roller assembly so that the centering and aligning mechanism acts upon the sheets before the sheets are engaged by the D-roller assembly. The centering and aligning mechanism includes a pair of elements extending parallel to, and symmetrically from the center-line of, the path followed by the sheets and the elements cycle from first positions inward to second positions separated by approximately the width of the sheets so that sheets positioned between the elements are centered a aligned. Movement of the elements is synchronized with the D-roller assembly by a pair of complementary oppositely faced barrel cams mounted on a common shaft with the D-roller assembly. To center and align the sheets the D-roller assembly is rotated to cyclically open and close its nip and the elements are cyclically moved between the first positions and the second positions so that the elements reach the second positions while the nip is open, remain in the second positions until the nip closes, and return to the first position before the nip begins to close again. Sheets are fed into the D-roller assembly and between the elements during each cycle while the nip is open and the elements are approximately in the first positions.