| 摘要 |
<p>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. </p> |
