Method and apparatus for forming and collating printed signatures

Abstract

A system for forming and collating printed signatures is disclosed in which a plurality of web supply rolls feed a plurality of continuously operating presses. A rewinding mechanism is provided to form printed web rolls which may be stored until printing has been completed for the entire publication. Slitting apparatus is provided longitudinally to cut each printed web into a plurality of printed ribbons which are thereafter collated to form one or more composite signature ribbons. Folding apparatus continuously folds each signature ribbon longitudinally and the folded ribbons are cross associated to form a compound ribbon moving substantially parallel to the gathering conveyor. The compound ribbon is cut into individual signature sets which are conveyed to the gathering conveyor.BACKGROUND OF THE INVENTIONThe present invention relates to a method for printing and collating individual signatures to be assembled into a magazine or book, or the like. In particular the invention relates to a signature forming system including a method consisting of slitting a printed web into a plurality of individual ribbons, and collating and folding the ribbons and conveying the folded ribbons in a direction parallel to the signature conveyor for separation into individual signatures to be deposited on the conveyor.Heretofore, signature printing and collating systems have been provided in which printing is applied to both sides of a sheet which is thereafter folded into a signature or section of a book or magazine. The folded signature is then placed in a hopper. Identical signatures are placed in the hopper and the hoppers are linearly arranged in accordance with the order of the signatures in the assembled volume. The signatures are removed one at a time from each successive hopper and placed on a moving conveyor. As the conveyor advances, signatures from successive hoppers are stacked for binding. The conveyor includes pins which project upwardly from the surface at predetermined intervals to push the stacks of signatures. This collating arrangement is slow and inefficient since it involves complicated folding equipment having excessive mechanical action. In addition, such prior types of collating systems usually require large press crews to keep the complex mechanical equipment operating, and are thus relatively expensive.Other prior types of collating machines have provided a main signature conveyor and an plurality of short signature transfer conveyors associated with signature dispensers linearly arranged along the main conveyor. The transfer conveyors are generally horizontal but move in a direction perpendicular to the main conveyor. As the main conveyor advances from one dispenser to the next, successive signatures are delivered by the transfer conveyors and are stacked on each other. The major disadvantage to this method is that the collating conveyor pins accelerate the individual signatures at a very high rate. If the signature has not had time to settle, air beneath the signature may cause it to plane, with the result that it may leave the conveyor or double back into the next section. In such systems, the signatures have been known to become disarrayed so that extensive jogging is required properly to orient the signatures. This increases the mechanical complexity of the apparatus, and hence the overall cost of the operation.SUMMARY OF THE INVENTIONThe present invention provides for a web binding system which includes a plurality of web supply rolls, each of which feeds a continuously operating press. The printed webs are rewound and stored until the printing is complete for the entire volume. The printed webs are thereafter slit into a plurality of web ribbons having a width corresponding to the width of unfolded signatures for the volume to be published. The ribbons are superimposed in a predetermined order to form at least one unfolded signature ribbon which is folded longitudinally and repeatedly cut to form signatures. Signature ribbons may be superimposed before being cut, depending upon the nature of the signatures required. Discrete signatures are conveyed to the signature gathering conveyor by a transfer conveyor which runs parallel to and substantially at the same speed as the gathering conveyor.

Description

Claims

1. In a method for forming and collating printed signatures for deposit on a signature gathering conveyor moving at a predetermined substantially constant speed in a path of travel including printing on a moving web, slitting the moving web longitudinally into a plurality of moving slit webs, superposing the moving slit webs to form at least one collated ribbon and folding the collated ribbon longitudinally, the improvement which comprises rewinding a printed web after printing and before forming the collated ribbon, unwinding the web before forming the collated ribbon, feeding the folded and collated ribbon toward and in substantially the same direction as the direction of travel of the gathering conveyor, cutting the folded and collated ribbon transversely at spaced intervals while feeding the folded and collated ribbon in substantially the same direction of travel as the direction of travel of the gathering conveyor, said cutting step partially but not completely severing the ribbon to form a group of folded, interleaved cut signatures still partially joined to said ribbon and advancing the cut signatures following the cutting step at an accelerated rate approximating the speed of the moving gathering conveyor to separate the cut signatures from the ribbon and to deposit them gently in a registered position on the upper surface of the span of the gathering conveyor.