Stop for top layer protrusion
Stops for surface layer projection are used in all areas where veneered panels require further processing.
If a derived timber panel is coated with veneer then this is usually present on all sides following the pressing process. If the panels require further processing at this point, it is not possible for the relevant edges of the bearing panel to be applied to a continuous stop for the correct alignment of the workpiece.
A wide range of solutions exist for positioning the veneered workpieces precisely and assuredly despite this. These are founded on two basic principles:
1) The stop consists of numerous very thin lamellas with intermediate spaces, so that the overlapping veneer fits into one of the intermediate spaces. The advantage of this variant lies in the fact that the workpiece edge is guided along the actual stop. The disadvantage lies in the comparatively complex and therefore cost- intensive construction.
2) The stop has one or more overlapping lamellas, which fit between the upper and lower surface layers and lie against those of the actual workpiece edge. The advantage lies in the very simple and economical construction. The disadvantage lies in the fact that the workpiece is positioned a slight distance from the actual stop and therefore assumes a different position to a workpiece without an overlapping surface layer.
Use of CNC-processing
The largest application field for stops for surface layer projection is stationary CNC-processing. The second variant is used here almost exclusively.
For the purpose of aligning the workpiece, almost all manufacturers use metal cylinders fastened on the machine table, which are positioned at a right angle. Mounted on these metal cylinders are spacers, which reach between the two surface layers. It is possible to position the workpiece against these. These devices are usually simple to activate, e.g. it is possible slide them in or fold them round. The simplest variants are screwed on the stop cylinder.
The manufacturer Weeke has created a special solution here, whereby a continuous stop bar is used in place of cylinders in many of their machines. Here, the surface layer projection is also continuous and can be folded out.
With many modern machines the control automatically detects whether a stop is used for projecting surface layers, and corrects the workpiece's reference point accordingly. Otherwise the operator is required to consider this themselves during programming, whereby the stops may pose a potential failure source.
Application in the panel cutting technology