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maquiza
06-02-2008, 01:10 PM
Is it possible to do threading with a VFD in the spindle, in a Lathe with Yasnac control? I have an Hitach J100 for 5HP, I belive it´s flux vector. The VFD does not have an index input nor A/B signal inputs.

Thanks in advance.

Jorge

Al_The_Man
06-02-2008, 02:28 PM
Most CNC spindles are VFD-like in Nature, some a little more sophisticated, but the general method is to use an encoder on the final spindle shaft and sync the Z axis by way of the encoder index pulse, with commercial controllers, the Z axis is then geared off of the encoder pulses, so even if the spindle speed varies slightly, the Z will track the correct feed.
Obviously the controller requires the Threading option, also the encoder is used for CSF (Constant Surface Feed).
Al.

maquiza
06-02-2008, 02:45 PM
Ok, then the Yasnac is controling the threading function? And the flux vector VFD is only monitoring the RPM´s acording to the voltage command?
It that how this works?

Thanks,

Jorge

Al_The_Man
06-02-2008, 03:39 PM
That is how the majority of commercial systems work, although some have more sophisticated spindles that others, it is easier to obtain precise control of the Z, rather that sync the spindle, in any case with an encoder on the main spindle, any variation in spindle gears etc such as backlash or variation in gearing etc, is not an issue.
Al.

maquiza
06-04-2008, 12:49 AM
AL,
One last thing, do you know if this VFD can work with 1 Ph.?
Thanks,
Jorge

Al_The_Man
06-04-2008, 09:28 AM
According to Hitachi, the highest SJ100 usable on 1 phase is 3 hp model.
Al.