The accuracy of the bend obtained on a press brake depends on a certain number of parameters related to the quality and mechanical characteristics of the material. Between batches of materials, and even between individual sheets, considerable variations may be can prevent the required bend angle from being achieved the first time.

In the early 90s, mechanical sensor systems were developed to provide angle measurement and correction on press brakes. The principal behind such a system involves taking intermediate measurement readings during the bending process, with a relaxation of the bending pressure in the final phase of the bending cycle, thus enabling the elasticity or spring-back of the material to be measured.

This procedure has certain disadvantages. It extends the cycle time by several seconds, and the measurement of the elastic spring-back takes place in a phase of considerable uncertainty. Measuring the elastic spring-back while in the deformation stage can, in certain cases, turn out to be very different from the definitive value used to determine the precision of the final bend.

To overcome these disadvantages, the LVD Group of Strippit, Inc., Akron, Ohio, developed the Easy Form Laser System for PPEB Series press brakes. This system uses a laser to make symmetrical measurements at the front and back of the die to determine the exact angle of the workpiece. The system projects straight lines composed of multiple light points onto the workpiece and vertical part of the die, providing a measurement calculation every 20 milliseconds.

The device transmits information in real time to the CNC control unit, which processes it and subsequently recalculates the correct depth adjustment to obtain the correct angle. The bending process is not interrupted, so the cycle duration is not extended and no production time is lost. In addition, the laser system provides accurate results consistently, and does not require calibration after each setup.

A high-precision press brake equipped with the Strippit/LVD CADMAN-CNC control can ensure the consistency of the bend over the entire length of the part, and the CADMAN-CNC database features a full range of values for the elastic spring-back of a variety of material types and thicknesses. When new materials are folded, their values will automatically be added to the machine’s database and used in determining the exact position of the upper beam to achieve the required bend angle.

When programming parts in CADMAN-B 3D, the software automatically assigns the Easy Form Laser units to the correct position for all the bends, even if a multi-bend set up is required.