US 4,360,354 AGranted

Machine for the treatment of web material

AssigneeThe Deritend Engineering Company Limited

InventorThomas D. Bishop

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Abstract

A die-cutting machine comprises two form-carrying rolls (10,12) operable in timed relation to produce alternate blanks, with minimum wastage between the blanks, from a web fed at constant speed by a conventional feed mechanism (14). The rolls (10,12) are driven by computer-controlled variable speed high impulse duty D.C. motors (28, 30) supplied with electrical power from thyristor controlled power supplies (36,38). Sensors (18, 24, 26) provide feedback signals representing web speed and instantaneous roll positions and speeds to the programmable computer units (32, 34). The use of the computer-controlled D.C. motors avoids backlash problems in previously proposed mechanical drives and allows greater flexibility, especially in maintaining registration between the rolls and preprinted areas on the web. A flywheel arrangement is employed to reduce the loading on the motors during large variations in roll speed.

Claims11

Dependent claims

A machine for treating continuous web to produce a series of longitudinally successive blanks, comprising at least two sets of treatment rolls each including a form-carrying roll for cooperation with the web, and means for feeding the web at a substantially constant speed successively through the nips of said roll sets, wherein the improvement comprises

(a) a variable speed electrical motor connected to drive each form-carrying roll through a constant speed transmission,
(b) a sensor connected to each form-carrying roll which provides an electrical output representing the instantaneous roll speed and the location of a datum position on the roll,
(c) a programmable computer, responsive to the electrical output of said sensor, which controls the speed of each variable speed electrical motor to drive the connected form-carrying roll at a constant speed while the form engages the web, and at a programmed varying speed during the remainder of each revolution of the roll to maintain close spacing of the successive blanks produced by the form-carrying rolls, and
(d) means associated with each form-carrying roll for transmitting energy in a selected direction between said transmitting means and said roll during said remainder of each revolution of said roll to assist the connected motor in varying the speed of said roll.

1 more element

Dependencies are inferred from the claim text.