Good Evening All,
I've been sitting on two mori seiki slant bed machines for a couple years both with varying control issues. Basically resigned myself to parting off the controls and doing a retrofit.
I keep meaning to sit down and write out a post with my intended plan at some point with a couple options, but never seem to get to it. Decided I was just going to start the thread and get some feedback on a few things.
First off: Spindle Motor and drive. The drive is a Yaskawa Varispeed 626MT (7.5KW) It may be ok but I had some trouble with it back when I first started turning the machine on. First I got a fan alarm. Checked fan all is ok, re-installed fan and now have a overspeed alarm (without the machine trying to turn the spindle on) So I'm thinking I might have a failing drive.
Option 1: dink around with drive a bit more maybe pull it an bench test it with the motor an see if I can get it running without the control attached.
Option 2: Buy a new drive from Mactech. (I think I've seen him post that he or his company stocks new drives. If so I'd be interested in a price)
Option 3: Replace the drive with something like a 7.5KW hitachi Sensorless vector drive.
For the motor (pic of the sideplate attached) Looks like a High speed induction motor with a resolver attached. If I go with a new hitachi drive I'm thinking I would probably ignore the resolver. I'm not sure what the detriment there would be as the spindle has a encoder on the belt drive between the motor and the spindle. I'd be feed that encoder back to the centroid board which should give me rigid tapping ability as well as speed control. (Not sure that the encoder feedback to the centroid is going to perform the same job as the resolver did in that I'm not sure it will push to maintain a set rpm or not).
For the servo motors Which are 400w continuous 2.0 kw peak yaskawa DC cup servos I was thinking I might try to change out the encoder and run them on gecko or similar drives, but I'm thinking in the end i'm probably just going to go with 1.0KW or possibly 1.8KW DMM servos and replace the servos and encoders wholesale.
For the control I'm thinking I'll probably start with a centroid acorn. It won't allow me to control the turrent so I'm going to handle the turret, spindle clamp, and tailstock on a seperate PLC. Not really a safe way to run if you don't know the machine. Just meaning I'm aware that without interlocks I could absolutely unclamp the spindle mid cut and the control would neither know nor care. Long term if I'm happy with the centroid interface and actually pull this off I'd probably spring for an oak board with the plc expansion board and get it all running together.
I'm kinda hoping mactech will chime in as I know he has some experience with the drive I have, and he a pretty big proponent for the DMM servos.
My first instinct is to move towards a new modern spindle drive so I'll go with that assumption and ask the following questions.
- Do I need to use the resolver feedback from the motor or am I ok not to?
- What side effects will not using the resolver feedback cause?
- Without the resolver what drives are compatible with this motor. (I'm thinking most modern sensorless vector drive VFD probably are)
- Can anyone say with certainty how I'd set that drive up? (Might help if I knew which drive) I'm guessing I'd run 240 volts max with a base frequency of 50HZ and Max frequency of 172 hz (Motor can do more, but spindle is limited to 5000RPM) drive would be hooked up to motor 3 phase inputs and any thermal inputs. Would want to run the fan off a relay to come on at full speed on anytime the drive is active.
- With encoder feedback to the centroid I'm guessing I'll be able to thread and rigid tap agree?
That ought to be enough for now.
Thanks again in advance for any input.