[jakubCZ]

Hi, I'm here on the forum new and I'm from Czech republic and therefore is my English too good.

I have a problem with my machine Cincinnati Arrow 500 from 1995, the control system Acramatic A2100, servo motors and servo drives are VICKERS (kollmorgen) black BDS4.

A month ago I had a problem on the X axis where the servo drive reported the same error FOLD BACK and it just appeared after starting the machine to me and pressed the green button, everything boots up but the engine you will start to twitch and when you try to shift in the axis of the row the engine jerks and will remain standing after the next attempt to shift the machine turns off the drives and reports an error.
This problem I solved in exchange servo drive system.

Now I have the same problem on the Z axis but in addition with the fact that after you start standing up fell headstock down to the vise that was under it. Now I've got the engine disconnected and when you start you engine is twitching and on the BDS 4 lit mistake to FOLD BACK.

I shoot video on my phone and I'll put it here in order to see how the machine behaves.

For any advice I will be very grateful.

[petesurrey]

Hi it sounds like either Drive or motor.
I wouldn't expect motor on a Z axis as it is not close to coolant unlike X axis. I have had this problem on X axis and it was one phase on motor gone down to windings shorting.

Check your DC bus voltage thats normally the first thing I check.

[jakubCZ]

Hi it sounds like either Drive or motor.
I wouldn't expect motor on a Z axis as it is not close to coolant unlike X axis. I have had this problem on X axis and it was one phase on motor gone down to windings shorting.

Check your DC bus voltage thats normally the first thing I check.

Hi, yes it is clear to me that the error can be either motor, controller or cables. I didn't understand why but jselo the spindle all the way down. At all stages I have - 110V and between phases -230V. How can I eliminate the error in the motor or in the controller?

[petesurrey]

ok i would recommend that first you disconnect the motor from drive and check the resistance between phases they should all be the same. If they are not then the fault is with the motor.

If they are the same check the resistance between phases through the cable. If this checks out all ok then you are best to swap the drive out for another axis and see if that swaps the fault to another axis.If it does then you know its a drive fault.. sorry i missed that the z axis fell that sounds bad the drive when in fold back should give the fault signal for the brake to re-engage.

This is how I would go about resolving your problem.

[jakubCZ]

It is possible to swap the controller from the X-axis on the Z axis? Between the axis of the X, Y, and A are the controllers the same but the Z axis is different.

[petesurrey]

The Z axis driver is different because the motor is higher rating but for test purposes you should be able to swap driver. You cant run the machine like that but it would certainly help to diagnose the fault.

Please support your z axis with wood so you dont plunge rapidly and damage anything. The brake is controlled by the controller not the drive from memory.

[meckardt55]

The X axis motor cable needs to be replaced, it is shorting out and causing the foldback error or the X axis motor if full of coolant. The Z axis problem is that the motor brake is not holding and you need to take it apart and check the gap. It should be about 0.008" to 0.010" between the bottom plate and the spring housing.

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