Mitsubishi Meldas Control and Motors

Hi All,

I have an old VMC that is based on the Mitsubishi Meldas controller and Mitsubishi motors. The machine is in good mechanical condition but the control has given up the ghost, so I plan to replace all the servo drives and do a new controller based on LinuxCNC. 

A few questions that I'd like some input on:

• The machine has 3 phase 1kW, 3000 RPM motors on it for the X and Y axes and 2kW, 2000 RPM for the Z axis - they are Mitsubishi HA83  and Mitsubishi HA103 and have rotary encoders on them that means the original servo drives keep track of the absolute position. Does anyone have any thoughts on sticking with this motors or replacing them?  If replacing them, any suggestions for a good brand/family?
• If I just replace the drives, then it seems that the Nidec/Control Techniques Unidrive M700 series might be a good choice? Any thoughts. Ideally I would power the drives directly from the 3 phase 415V supply (the machine currently has a transformer which delivers 200V to the drives).
• On the control side, any suggestions as to which Mesa cards are well suited? Previously I have converted machines using the 7C81 and a Raspberry Pi and 5i25 and PC - I think this will need quite a lot of I/O so I'm thinking a PC based card this time.

Thanks,
Greg
 

If you have absolute encoders, I think the best solution is to buy new servo drives and motors. Some good brands are Yaskawa, Delta, and CTB. I personally chose Adtech

You might also want to have a look at dmitry's interface cards.
yurtaev.com/

One option would be a stmbl v5: github.com/freakontrol/stmbl
There is also a thread on the forum.
I have it running with smaller Mistubishi Motors, your encoders should be supported. The HA103 Motor is on the upper power limit, but it should be fine. It can run the 200V motors direct from mains voltage without a transformer.

Greg,

Right now, you have a machine in good mechanical state. The only problem you have with this machine is the controller. My advice, do not remove or dismantle any component at this stage. 

1-Gather the manuals wiring diagrams and any information you can find. 

2-Study the servo drive CONTROL METHOD (analog, digital, industrial communication bus etc …) 

3- Study existing wiring diagrams and determine the number and type of IO’s (sourcing/sinking) 

4- study the type of controller you will need, the type of daughter boards needed and type of PC (pci/pcie/ethernet/Mitsubishi bus communication bus … etc 

5- Modify the existing wiring diagrams to reflect the changes required. Keep in mind that the machine was designed and assembled by highly skilled craftsmen, at this stage you will focus on keeping the modifications to existing components to a strict minimum. 

6- With all the above knowledge and mods you will be ready to configure the controller and choose GUI 


Note: machine integration requires patience especially if you have not done it before on a machine such as vmc. (Bounding, grounding, shielding can be nightmare, modifying the safety control system can become a liability and changing from sourcing/sinking io can be laborious, etc …), keep it simple stupid (KISS) is the answer to a successful project.

Hi Benb,

Thanks for your reply - pretty much exactly what I am planning on doing, in the past I have found that re-using the wiring loom on a machine can save days of time - particularly if it is well done in the first place. There is also the added benefit of all the high quality connectors and cabling that are already in place on the machine side.

The machine came with a fourth axis so I'm going to get that working in isolation before starting on the machine proper...

Thanks for the suggestions.
Greg