M16/iB Fanuc Gripper

[Jim Tyrer]

Hello All,
Have a M16 iB 20 with R3 JiB controller, the robot is used to unload a long and narrow plastic automotive molding from a fixture after processing.
The gripper is made of 30mm diameter aluminium tube, is about 1.9m long and is fitted with vaccum cups to be able to grip the plastic piece of car.
The problem is that when the gripper is bolted the normal rigid way to the robot, the 6th axis of the robot causes the gripper to oscillate like a fishing rod, and the oscillation goes into resonance and faults the robot. So what I have done is introduce a slice of polyurethane rubber in between the robot's flange
and the gripper mounting flange. It works but the bolts used to compress the rubber keep breaking off after a few weeks.
It has 6 M6X30 grade8 capscrews.
Have been thinking of replacing rubber with a balzylinder but mounting it would be difficult.
A photo of what it has now is attached

Question is:
If anyone else has been down this road your ideas would be appreciated.

[stefanM]

Hello Jim,

I estimate that the srews are breaking because of bending.
First I would try to use other Srews 12.9 instead of 8.8. If this does not make it better: can you decrease thickness of the PU slice??
An other way is to inrease tension of the screws (this will change dampening, resonance frequency and make it harder)
Or mount two adapters of aluminium (the rubber in between) and use bigger screws.

For different use : compliance wrist e.g. IPR FM-160 (www.ipr-wordwide.de) - I don´t know if it´s pretty good for your problem.

BR Stefan

[Jim Tyrer]

Thankyou Stefan
the IPR wrist is EXACTLY what I need.
the customer wants to have no screws at all, their maintenance staff have to keep changing them.
Jim
These sites are WAAAY cool 

[WolfHenk]

The problem is the oscillation.
This happens by resonance of the Gripper withe the Robot.
I think, you have a movement (fast, linear and "fine") in tool -z direction
Maybe it is easier to decrease the resonance by doing some easy physics: Maybe it helps, maybe not...
Try to mount a steel rope inside the 30mm Alu-Tube of 1,90 meter length. It must be not at the center of tube