Size Matters: High Force & High Speed: VFD Controlled Hydraulic Power

Compact Hydraulic Power Unit- uses variable frequency drive (VFD) 

  • 12-Ton Clamping Force
  • 7 Inches per second Velocity
  • Hydraulic Power unit to fit within the base of the machine
  • Minimal Heat Generation by Hydraulic System
  • Machine cycle time of 20 seconds

Our application required High force, for clamping and Marking/stamping the part. The clamp mechanism is also the transfer mechanism for switching the part.

Typical Hydraulic power units are sized to disperse heat, most of which is generated by the pressure drop across valves. If this were a typical power unit, the reservoir would have been 60 gallons. A radiator or heat exchanger would constantly be removing energy from the oil.

The goal of the system is to fit the hydraulic power unit into the frame of the machine.

The dual pumps, one large pump for high volume and a second small pump for high pressure, were staged during the machine cycle. During the shuttle transfer, both pumps ramped up to 3200 RPM, for high volume oil at low pressure. As the hydraulic cylinder reached the clamping position, the VFD speed ramped to 300 RPM, while the high volume pump merely circulated oil back to tank at nearly zero pressure.

In our design, there is very little heat generated. The 5HP motor and VFD for the  power unit requires full torque while clamping, but this is only at 300 RPM. The actual horse power is less than 1HP.

During the shuttle transfer, there is little resistance to motion, while the motor/VFD/pumps are rotating at 3200 RPM. The actual horsepower is again less than 1HP.

This unique solution is part of a innovative project.  See more: Auto Tapper- Multiple VFD Solution

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