Renovating a Hardinge HLV-H

[BillTodd]

Hi Jonathan,

Good to hear from you:)

.. be good to see a new Schematic and even more interesting would be the New HLV that has just come out, with the servo leadscrew.

Yes it'd be nice to know if the lever still directly controls the speed change or weather they are just using a single speed motor and a clever VFD. (I suppose it would even be possible to design a dual output VFD just for dual speed motors)

Quick question,, with regards to the brake, you are still retaining the mechanical brake solenoid. This is the way I would be doing it, but thinking about it there may be some merit in using the inverter to do the braking, what are your thoughts on that?

I'm retaining the mechanical brake as it is useful for collet changes etc.. ATM it will only operate when the lever is in the STOP position (or when the spindle lock is ON). During ramp down for speed changes, the VFD does all the braking. Incidently, I found the VFD slowed the machine faster, without faulting, using the ramp down without dc injection.

It's a real pity that my VFD's 'catch spinning motor' routine doesn't seem to work 'as advertised'. If it is has to speed-up the motor (i.e. when changing from low to high speed) the motor complains loudly. The high to low speed transition was flawless. (I guess it ramps down from max frequency ).

The auto transformer you are using is single phase, are you doing the same as me and feeding the inverter with 400V single phase ? and not running it at full capacity ?

The Siemans VFDs are rated at full power while working on single phase (many [most?] that will run on single phase will not need to be derated - it's only losing two diodes in the bridge rectifier, if the remaining four will take the extra current there's no need to de-rate the VFD)

I should really get some pictures of mine on this forum.... I have just got to the primer & paint stage, (lotts of dammage to my carrige gears + rebuilding the carrige feed motor + revising its electronics have taken a lot of time) Best Jon P

Yes do post here I'd love to see it.

I'd be tempted to replace the DC motor with a smaller 3ph one and use another small VFD for power feed - It'd have a much better speed control

Sorry to here about your carriage gears. Are new ones very expensive? :(

[aafradio]

It's a real pity that my VFD's 'catch spinning motor' routine doesn't seem to work 'as advertised'. If it is has to speed-up the motor (i.e. when changing from low to high speed) the motor complains loudly.

You might consider changing the sampling frequency as an experiment. If the motor is emitting higher frequency noises, it's often a function of mechanical resonance of the windings under load.

The Siemans VFDs are rated at full power while working on single phase (many [most?] that will run on single phase will not need to be derated - it's only losing two diodes in the bridge rectifier, if the remaining four will take the extra current there's no need to de-rate the VFD)

The size of the filter capacitor on the DC bus actually has more to do with derating than the size of the diodes, though of course the diode rating has to be considered for single phase feeding of a larger capacitor bank. Most of the VFD's I've seen suggest a 1/3 derating...e.g., use a 3hp rated unit for a 2hp motor. That's consistent with the energy under the power curve for three phase versus single phase rectifier designs. The VFDs that are rated for single phase simply have a larger capacitor bank in them. If the supplied voltage from a three phase input design VFD sinks under a heavy cutting load, it is usually fairly easy to add capacitance to the unit externally to solve the problem. The risk is exceeding the current rating of the internal diodes because they are charging a heavier peak load in each cycle. It's usually not a problem for reasonable (<50%) increases in capacitance, but needs to be checked.