To realize the maximum production capabilities of a roll forming machine, including continuous operation and the improved product consistency available by feeding coiled stock, a cutoff machine becomes an important part of the complete roll forming system. The machine in most general use is similar to the 4-post model on Figure #15 and might be pictured as an under-driven press with rails fastened to the bolster plate and to the ram. The flying cutoff die is free to slide on the rails from right to left. These machines function to cut the formed section to length as it exits the roll forming machine without stopping the forward progress of the section.
The section passes through the die and travels along a runout table until the desired length is measured, either via a rotary encoder, photo-eye, limit switch or a positive (mechanical) stop. This target initiates the cutting cycle, and during the period of cutting, the die moves from right to left on its slide rails. Once the cut is completed, it returns automatically to its starting position.
This is the most simple form of operation. However, the cut length tolerance can be very broad, depending on line speed, the type of cutoff press, and method of length control employed.
Other methods of actuation for a cutoff operation include:
