Hydraulic and servoelectric drives usually are considered to be "competitive" technologies. However, the best performance from a machine often can be gained by capitalizing on the benefits of both technologies. Such is the case with HYB series of hybrid press brakes from Toyokoki, a division of MC Machinery Systems Inc., Wood Dale, Ill.
The HYB line was developed by combining the strengths of a conventional hydraulic press brake with those of an ac servo press brake. The hybrid machines rely on pressurized hydraulic fluid to extend a ram, but the pump is powered by an ac servo motor that provides precise control without control valves. Instead, pressure and flow are controlled by motor torque and speed, respectively.
Toyokoki's conventional hydraulic press brakes allow users to easily change ram speed and force. Immense power and high speed can be achieved from a relatively small amount of energy. Their conventional ac servo brakes, on the other hand, use a ball screw driven by an ac servomotor to achieve extremely high repeatability and positioning accuracy within microns.
The HYB Series combines the speed and force of hydraulics with the precise positioning of ac servodrives. The hybrid machines achieve repeatability of 5 µm (0.0002 in.). They control ram speed and positioning with 1-µm resolution scales that read ram position 1000 times a second. In turn, feedback is sent to the ram ac servomotors to ensure that ram velocity is constant and no overshoot occurs. Company officials mention that no other press brake monitors its ram position and velocity to prevent overtravel or over-bending.
This information was provided by MC Machinery Systems Inc./Toyokoki Press Brake. Call (630) 616-2970, or visit www.mitsubishi-world.com for more information.
