| 摘要 |
<p>In machines for cutting a sign text or sign symbols in a working web of plastics it is usual that a coordinate controlled working head (10) works on a web length (18), which is laid out on a table (2) and is unreeled from a supply reel (16) such that new web lengths can be laid out on the table when the need arises. The web is pulled forward by means of a transverse, short driving roller (24) located at one side of the front end of the table, whereby the roller can advance both broad and narrow webs, which should always have a side edge located along a specific reference line of the table top. The web, during the pulling forward thereof, may easily leave that line, outwardly or inwardly, and it is important to adjust the new web length into a correct location both longitudinally and transversely. The invention provides for an automatic lateral guidance of the web (18) by a simple detection of the location of the reference edge thereof and an associated control or changing of the transverse direction of the driving roller (24, 26) for imparting a compensating cross movement of the web length being advanced. Also the lengthwise movement is controllable in an accurate automatic manner.</p> |
