1. Field of the Invention
The invention relates to a driving means, which can be used in a device for working sheet-like material, such as a press brake for bending steel sheet.
2. Description of the Prior Art
A driving means for a press brake is known from European patent application No. 0 384 529. The disadvantage of such a driving means is the limitation of the available press force per length of the beams. This limitation is for example the result of the tensile strength of the belt. An increase of the belt width in order to increase the tensile strength would limit the maximum bending angle of the device for certain products when bending sheet-like material. By increasing the belt width, the width of the beams is increased, which in turn results in a higher chance on collisions between the sheet-like material and the beams.
Another limitation is related to the electric motors used for driving the belt. If the pressure force of the device would be increased the power of the electric motors should also be increased resulting in larger motors having slower dynamics which has an impact on the speed with which the device can be operated.
Yet another limitation of the driving means according to the prior art, is the limited number of rollers in respect to the length of the driving means. Reducing the diameter of the rollers, to increase the number of rollers, would only partially increase the press force. When the diameter of the rollers is reduced, the belt has a smaller bending radius, which reduces the maximum tensile strength of the belt.