Roll Forming Line Automation, Part 4: Optimizing Line Speed
In the previous blog posts, we covered the various types of flying dies. In this post, we will discuss techniques for improving the line speed and efficiency of production lines with flying dies.
Methods to Reduce Die Sliding Friction
Fighting the resistance to sliding is one of the big problems constantly faced when building “flying” dies. Anything that can be done to lessen the resistance to movement of the die will increase the line speed.
With light dies, linear roller bearings and shafting can be used. Instead of the die riding on slides mounted to the bolster plate, linear bearings are attached to the die. These bearings ride over hardened shafting mounted to the bolster plate.
A method used to lessen friction on medium-sized die cutting on high-speed lines where rapid acceleration is necessary is to let the die roll on a series of rollers trapped in a cage.
The method used to reduce friction on large dies or on dies that require much tonnage to cut off is a receding roller bearing.
Press Requirements for Accurate Length
Another subject which cannot be left out when talking about dies is the punch press.
There are two important things to look for in a press for a cut-off die:
- The RPM of the press — the faster the better
- The consistency of the top stopping point (or rest position) of the ram.
The RPM are important when considering that there is always some fluctuation in line speed. A 300-RPM press will show only 1/3 of the error that a 100-RPM press will show when we get a line speed fluctuation.
The consistency of the top stopping point of the ram is very important and affects the length accuracy whether the line speed fluctuates or not.
It goes without saying that the faster the press is, the less linear die travel we get. Therefore, for an additional investment to get a faster press, a person can probably run a roll forming line faster with less problems and better length tolerances for the life of the line.