- Part 1: Web Guiding Systems in Roll to Roll Winding System
- Part 4: Unwind and Rewind Guides in Roll Winding Systems
- Part 3: Web Displacement Guide in Roll Coating Systems
- Part 2: The Web Steering Guide in Roll to Roll Systems
- Part 6: Acceleration Offset in Roll to Roll Web Systems
- Part 5: Guide Accuracy and Response in Roll Winding Systems
Web Displacement Guide
When a sufficiently long entry span is not available, a displacement guide may be a better choice. The displacement guide, as seen in Figure 3, is a system of four rollers. The first and last are fixed, while the center two rollers pivot on a common frame about the center of the upstream roller. The web sensor must be located very close to the exit of the third roller. While this is the most common depiction found in advertisements, the system can be arranged in at least 16 distinct ways, each of which have four orientations. These numerous equally effective possibilities allow considerable machine design flexibility.
The only real design constraints are that the spans entering and leaving the pivoting table must be at least 1/2 web widths long, but the three legs can be of different length. Note that the length between the pivoting rollers determines the effective sidelay range for a given twist of the web.
There is an important difference between the behavior of the displacement guide and the steering guide. While the steering guide will move the edge of the web upstream and consequently also downstream of the guide, the displacement guide will move only the downstream web path. Thus, the upstream process must be tolerant of uncontrolled web CD (cross direction) position.
Written for Faustel by David R. Roisum, Ph.D.