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Thread: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

  1. #41
    Member TomKerekes's Avatar
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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    With P Gain of 0.02 the system is now very stable. Probably too much. Adjust the level of P Gain to find the maximum value of P Gain that is still reasonably stable.

    I forgot to tell you to increase the max limits. Max error of 200 and P Gain of 0.02 limits the output to 4 DAC Counts (0.02V !!). Please read this and let us know what you understand and don't understand.

    Regards
    TK http://dynomotion.com


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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    I understand the concept of the Max Limits. I can't say I understand how it all interacts. I tried quite a few combinations today. It seems to me that any P Gain value greater than 0.01 caused oscillation, at least with the other values that I was using. The following plot is the best I found, although the P Gain caused a low Output limit.

    What is the best way to post Data files?

    Warner/Swasey QCM-6 lathe with Kflop/Kanalog-stepresp11-png.



  3. #43
    Member TomKerekes's Avatar
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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Hi Charles,

    Hmmm. That seems very low P Gain to be stable. I'm wondering if the tach is working. Without tach feedback a system with only P Gain is unstable. This is because motor torque (and acceleration) continues right up to reaching the target. Just like a pendulum. The only way it is stable is if there is some friction. The Tach effectively provides drag. Instead of the acceleration reducing to zero at the target the velocity reduces to zero at the target. Very different. D Gain works similarly to Tach feedback. So you don't really need the Tach. But I don't like the idea of having a Tach and it not working properly.

    You might run some experiments commanding DAC voltages on the Console Screen. This is like the 1.5V Battery test but you can command any voltage you want. (Note the axis must be disabled). See if you can tell if the command voltage is commanding velocity or torque. If you command 10% (1V ~200 DAC Counts) does the motor move and maintain at a controlled 10% of max speed? If you apply resistance does it maintain the same speed? Or does it just keep accelerating to a high speed?

    I forget what amplifiers you have. Do you have specs? Is there a Tach Gain Pot? You might measure the Tach voltage right at the amplifier terminals while running the Motor at some RPM.


    What is the best way to post Data files?
    Use the Manage Attachments button, Browse, Upload to post a data .txt file. There might be a size limit. Reducing the Move Time will reduce the size or you can zip it.

    Regards
    TK http://dynomotion.com


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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Hi Tom,

    Drive # is Inland Kollmorgan TPA/2-15640-603-4202F2-4202I2. It is a combo drive, running x and z. From the manual,it is multi-axis three phase, half wave, four quadrant, fully regenerative SCR "Rate Loop" Servo amplifiers. It maintains a speed proportional to a command input signal.

    Tach appears to be working. With DAC1=50, tach reads 1.5 volts. DAC1=-100 reads -2.2 volts.



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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    I have an electronic copy of the latest manual if you want it.



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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Tach appears to be working. With DAC1=50, tach reads 1.5 volts. DAC1=-100 reads -2.2 volts.
    The Tach appears to be generating voltage. It seems there is some offset itn the DAC or Amplifier.

    I think I found the manual. Seems to be a very old design and basically varies the portion of the 60Hz cycle phases that get applied to the motor. I think this type of amplifier has a relatively slow response.

    I'd suggest going ahead with the tuning to see what kind of performance you can get. You are now at step 4 here.

    Regards
    TK http://dynomotion.com


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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Hi Tom. I've been working on the tuning, reading through PetertheWolf's thread. Is it normal, if you do a "Move" several times with the same settings, to get different results? I'm seeing Outputs ranging from 80 to 150 without changing anything. I have checked the motor to ballscrew coupling and the encoder disc to be sure they are tight. Most of the time the variations are not that much, but seldom are they close to the same from one "Move" to the next.



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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    if you do a "Move" several times with the same settings, to get different results? I'm seeing Outputs ranging from 80 to 150 without changing anything. I have checked the motor to ballscrew coupling and the encoder disc to be sure they are tight. Most of the time the variations are not that much, but seldom are they close to the same from one "Move" to the next.
    Hard to say. 70 DAC counts is ~3% of full speed. Not huge but more than I would expect. It depends on the variations in the mechanics, friction, binding, and so forth. This is another indication that the Amplifier is not controlling velocity accurately. If it was the output (commanded velocity) would always be the same regardless of friction and such.

    Regards
    TK http://dynomotion.com


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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    These are almost 40 year old drives. The machine only has a little over 400 hours on the original control that I removed. However, I know capacitors go bad with time. It could be that the capacitors are causing the drive to have issues. I can check with Mike Kilroy about that. I can probably replace capacitors, if needed, but I need to try to use these drives if possible. This is a hobby machine. The x/z combo drive is 40 amps and the spindle drive is 85, I think. Replacements would probably bust the budget, unless someone knows of a bargain somewhere.



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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Looks like I need to adjust the drive speed pot properly. Hopefully that will help. I'm out of town until the weekend. Will get back to it then. Thanks again, Tom.



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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Hi Tom. I need to adjust my Z axis drive speed pot to show a reading on the command terminals of .80 volts at 1/10 max speed as commanded by KFLOP/Kanalog. How do I determine max speed and how do I command 1/10 of that speed? I'm assuming that it is done with a Console DAC command.
    Thanks,
    Charles



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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    More information: encoder is 4000 CPR. Direct drive to .200 ipr ballscrew.



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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Hi Charles,

    How do I determine max speed?
    Well that is sort of up to you. Your motors and Power Supply Voltage will limit what speed your system is capable of. Motors act like a generator when spinning. At some RPM it will generate some voltage. A power supply voltage higher than that is required to put current into the motor to generate torque. Once the motor RPM generates a voltage near the supply Voltage little torque can be created to go faster. That speed may be unnecessarily fast (and scary) for your needs so you may choose a lower maximum speed.

    I'm not sure where the 0.8V comes from. I suppose if max speed were to correspond to 10V then 1/10th max speed would correspond to 1V, so 0.8V would allow a 20% margin.

    Max DAC Voltage (10V) corresponds to 2047 DAC counts. So to command 0.8V:

    0.8V / 10V * 2047 = 164 DAC counts

    Console Command DAC0=164

    If the axis is working the opposite approach would be to command 1/10th speed then adjust the Speed Pot until the DAC Voltage is 0.8V. So for example if your desired Max Speed is 500ipm then 1/10 max speed would be 50 ipm. Converting to Counts/sec:

    50 ipm x (1min / 60 sec) x 80000 counts/inch = 66667 counts/sec

    So command Jog0=66667

    Regards
    TK http://dynomotion.com


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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Thanks Tom, for the detailed response. I believe the .80 volt setting is indeed a 20% buffer. That figure came from Mike, the Inland/Kollmorgan specialist who is helping me with the drives. I just needed to be sure about the Kflop/Kanalog output and how to get the correct value. I will post my results.



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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Hi Tom. I feel like I'm in a fog. Just can't see.
    I swapped the X axis drive MC2 (motor control card) into the Z axis slot. The pots have not been adjusted on them. They are still sealed. I disconnected the Z motor from the ballscrew. The motor seems to run a lot smoother with jog or DAC commands.

    Not wanting to break the pot seals yet, I measured the resistance from each end to the center tap and across both ends. I matched one end of the Z pot to the same end of the X pot. The other end is about 1 ohm higher on the Z pot. I put the original Z card back in the Z slot.

    Motor seems to run smoothly, about 200-300 rpm (guessing) with DAC1=164. Motor speeds up and slows down when the speed pot is turned left or right about 3 turns. Command voltage is .796.

    Jog1=165,000 gets about 600-700 rpm (still guessing), with .970 volts on the command terminals. Turning the speed pot changes motor speed.

    Not sure what all this means, but it looks better than what I was seeing before.

    Is there a way to get motor speed in RPM to display, based on the encoder? If I try to time the position counts, I think I'm getting about 83,000 counts per second at DAC1=164 (.797 volts).

    I think I'm ready to bolt the motor back on and try tuning again.



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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Forgot to mention, with Jog1=165,000, after running a few minutes, it stops with "Following error Disabled Axis:1"



  17. #57
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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Hi Charles,

    Jog1=165,000 gets about 600-700 rpm (still guessing), with .970 volts on the command terminals. Turning the speed pot changes motor speed.
    When Jogging with a proper closed loop servo the Jogging speed should be exactly what is commanded. So turning the speed pot shouldn't make any difference. The servo should adjust the DAC output to be whatever is needed to go at the requested speed. I suspect you have the max limit output set at 200 DAC Counts (about 0.970V). If you were to observe the Analog Screen you would probably see the DAC stuck at 200 counts. This is like putting a brick under the gas pedal in a car and trying to go 60MPH. The pedal will be against the brick with the car only going 40MPH. I don't know what the Max Following Error is set to but after falling behind more and more from where it should be eventually it exceeds the following error limit. Increase the max limit output up to 2047 to allow that amplifier to be command faster.

    Here is a program that should display the motor speed in counts/sec and RPM

    Code:
    #include "KMotionDef.h"
    
    #define AXIS 0
    #define DT 0.5
    #define CNTS_PER_REV 16000.0
    
    main()
    {
        double x,x1,t1,t,dx,dt;
        
        x1 = chan[AXIS].Position;
        t1 = Time_sec();
        
        for(;;)
        {
            Delay_sec(DT);
            t = WaitNextTimeSlice();
            x = chan[AXIS].Position;
            dt = (t-t1);
            dx = (x-x1)/dt;
    
            if (dx != 0.0)
                printf("Velocity = %f counts/sec %f RPM\n",dx,dx/CNTS_PER_REV*60.0);
            
            x1 = x;
            t1=t;
        }
    }


    Regards
    TK http://dynomotion.com


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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Hi Tom. Please excuse the dumb question, but how do I get the above C code where it needs to be, and how do I activate it?. I think I've still got issues with the drive. Trying to run tests with to adjust the speed pot. My results on pretty much everything are inconsistent. I don't have much hair left. Thanks for your patience.



  19. #59
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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Hi Charles,

    t how do I get the above C code where it needs to be, and how do I activate it?
    - Copy it to the Clip Board
    - Open KMotion.exe C Programs Screen
    - Select Thread #2
    - Select New and OK
    - Select all
    - Paste
    - SaveAs ShowRPM.c
    - Push the Save, Compile, Download, Run Button (with arrows)
    - Observe the Console Screen
    - Move the motor

    HTH

    Regards
    TK http://dynomotion.com


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    Default Re: Warner/Swasey QCM-6 lathe with Kflop/Kanalog

    Hi Tom. Thanks for the velocity code. With DAC1=165, command voltage is 0.80. Velocity is fluctuating 360-499. Tach reading is 1.8-3.0 VAC or 1.6-2.5 VDC. I think the tach is AC. I think the tach is causing the drive to not be able to hold motor rpm consistently, because it is "dirty"? I'm going to try to clean the tach commutator.



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