Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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perforating machine

A machine used for perforating paper. Two types of perforating machines are in general use: 1) the vertical, or flat-bed perforator, in which the punches and dies are set in a straight line, with the punches set in a moving bar and the dies in the surface of the table. Several sheets may be fed at one time between the punches and dies against adjustable guides. When the machine is activated, the bar descends and punches a series of holes in the paper. The punches are adjustable so that some may be removed when the holes are to be punched only part way across the sheet; and 2) rotary perforators, which are capable of punching round holes, slots, or slits. The punches and dies are mounted on discs that revolve against each other, the paper being fed between them, with one edge against a guide. This type may be set to perforate struck lines as well. Some types of perforators raise the punches for struck lines, while others drop the dies; however, in either case, the punches d o not enter the dies, so the sheets are left unperforated. This movement of dies or punches is synchronized with the opening of a paper gate so that the perforating will start at the desired point. The same result may be obtained on other machines by removing some of the punches. Rotary perforators can accommodate several perforating heads which are adjustable laterally on the spindles to change the spacing between the lines of perforations. The minimum spacing varies with different makes of machines.

The angle perforator can punch in both directions at one feeding. This machine is actually a combination of two rotary perforators at right angles to each other, with feed rollers to carry the sheets of paper from one set of perforating heads to the other.

By means of special attachments, most rotary perforators can also perform other operations, such as scoring, crimping, and slitting. (320 , 339 )




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