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X****Liu
Issues with TVM920 pick and place machine aligning components with small pitch
688 1 Sep 27.2019, 18:03:16

Hi everyone.
I am wondering if anyone had similar issues.
Our TVM920 machine seems to have issues with aligning of small pitched components.
It looks like it endlessly trying to turn the IC CW and CCW, and fails to get it aligned - it jumps over the correct position every time. 
Below is the video and the screenshot.
Our engineer have tested the 360 degrees rotation of the component.
As we know at 0.00° and at 360.00° the IC must be in the same position.
So he tested it at 0.00°, 0.23° and 360.00°.
The respective angles the machine "reads" are:
set angle: 0.00° - read angle: 3.90°
set angle 0.23° - read angle 4.21°
set angle 360.00° - read angle 4.21°
Conclusion:
When we order the nozzle to rotate by 360.00° the IC rotates by 360.23°.
Note that 0.23° seems to be one microstep of the stepper motor that rotates the nozzle. Typical steppers are 200 steps/rev. With microstepping = 8 it gives 1600 steps per rev, and as a result 360°/1600=0.23°
So this seems to be a bug in the software - they seem to have have the stepper make extra step when crossing 0 degrees set angle. Just a wild guess - but it very much looks like this! 

Anyone had that?   I contacted Huang in QiHe  tech support but no solution yet.
Thanks!

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A****min

Oct 10.2019, 14:41:43

You can check if with more illumination it works better. As you maybe have noted, the upper edge enclosing rectangle changes at the two angles relative to pins.
Try to put additional two leds as example to that area or just use desk lamp or 
torch. If that solves the problem, you could try to adjust illumination/camera shutter settings, and if that don't work, make better illumination.
To the driven angle and read/real angles, it could be possible that the actual/last fiducial angle correction was -3.90 degree or something like this and that was just
cal in , or that the machine have this offset itself when traveling.

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