Program idea, not sure if possible with given hardware/software

First off, i am new to ladder logic. I do have some experience programming microcontrollers in C. I will try and give a short version and if more details are required i will certainly provide them. I'm just not sure what i want to do is possible (with an AB Micro820 PLC)

What i this pertains to: A horizontal CNC drill spindle.


What i need to do: Install a VFD for the spindle, and be able to use 4 different gear ranges in the transmission. The reference sent to the VFD will need to take gear ratio of current gear into account. The current setup has 7 solenoids, 36 gear ratios, and a 1800rpm motor (no vfd).



What i plan to do: Install an AB Micro820 (and use the free version of CCW), feed the 0-10V reference from the CNC Controller to said PLC. The PLC will need to be able to decide based on the reference voltage what gear needs to be selected. The PLC will facilitate shifting the transmission via outputs to solenoids and a sequence that "bumps" the spindle a few times while proper solenoids are active to shift the gears. Once shifting is complete the PLC will need to output a 0-10V (or pulse train) speed reference that is relative to the gear selected so the VFD will run at the correct frequency for that gear to achieve the requested RPM from the CNC controller.


I by all means am ready to do my own homework as far as getting it done, but before trying to sort this out I'm hoping someone may be able to tell me if such an operation is possible with the given software/hardware, and if not, what do i need to get (i don't mind paying for the hardware but prefer not to spend hundreds - thousands on the software).


I am also up for ideas for a better approach. Any help on this is greatly appreciated.

Way to complicated and you haven't even done anything about the feed for the spindle
All you need to 2 Flux Vector VFD's no gear change
5000 to 1 speed range on the VFD will get you any speed you want
Set your spindle speed and the feed rate and that's it. it could be done with Micro 800 with little programming

GaryS said:

Way to complicated and you haven't even done anything about the feed for the spindle

Click to expand...

The feed is controlled by the CNC controller (Heidenhain TNC310).

GaryS said:

All you need to 2 Flux Vector VFD's no gear change 5000 to 1 speed range on the VFD will get you any speed you want Set your spindle speed and the feed rate and that's it. it could be done with Micro 800 with little programming

Click to expand...

If we went with one speed it would have to be the tallest gear so they can get 1500rpm out of it which is what they are needing. That would put the motor at approx 2400rpm. At the other end they run it as low as 80RPM, if i figure this right that would put the motor rpm down to 128RPM. I do not know how much power they use at that speed but i would be afraid to loose that much mechanical advantage going with a fixed, tall gear. Does that make sense?

Without the need to control the feed all you need is a single Flux Vector Drive
Standard max motor speed is 5,000 rpm on a 4 pole motor Base speed 1,800 rpm
no plc needed, just set the speed you want on the drive keypad and go
I have run feed rates at 0.2 hz so slow you can't see it run
with a good drive you get 100% torque through the full speed range
I have done jobs like this no problems

GaryS said:

Without the need to control the feed all you need is a single Flux Vector Drive
Standard max motor speed is 5,000 rpm on a 4 pole motor Base speed 1,800 rpm
no plc needed, just set the speed you want on the drive keypad and go
I have run feed rates at 0.2 hz so slow you can't see it run
with a good drive you get 100% torque through the full speed range
I have done jobs like this no problems

Click to expand...

You do understand that i am talking about the spindle RPM right? I am not talking about the Z feed. The motor is 25HP and has a max of 3600RPM. And yes i understand that it can produce full torque, but that does not account for the massive amount of torque multiplication that will be lost if we go with 1 gear. I'm not knocking your advice, i'm just going with the cover your *** method lol. The other drill we have that was retro-fitted by the "drill gods" as they are called around here where setup where they kept 4 ratios and the Fanuc cnc controller on it takes care of the shifting and speed and they are very happy with that machines performance. They want the other machine to do the same and be automated, no punching in numbers for spindle RPM when it is already specified in the gcode.

It really doesn't matter what you are controlling axis feed or spindle
the speed range is 5000 to 1 rock solid
now if you need a gear reduction to multiply the torque then you will need the gear with any drive I have seen motors running at 20,000 rpm
you 3600 rpm is no problem
that must be a big tool to need more torque then a 25hp motor
one other option would be to use a 6 pole motor or even an 8 pole motor but the 8 pole would be a custom motor

GaryS said:

It really doesn't matter what you are controlling axis feed or spindle
the speed range is 5000 to 1 rock solid
now if you need a gear reduction to multiply the torque then you will need the gear with any drive I have seen motors running at 20,000 rpm
you 3600 rpm is no problem
that must be a big tool to need more torque then a 25hp motor
one other option would be to use a 6 pole motor or even an 8 pole motor but the 8 pole would be a custom motor

Click to expand...

I'm not sure how big they go but i know they are drilling 5" holes through some very hard alloy (boiler). And it may very well work with one gear, i just don't know for sure and they don't want to hear that.

You first need to find out how much torque you need for the job and if I was specifying it, I would add about 10% to that what max speed do you need is the place to start
all those gears just add problems you don't need
most CNC's use control the load by controlling the feed rate
as I said you can control the feed rate using the same VFD
PM me if you want to get into details