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Motion of assy causes part interference

Question asked by Bulent Kalafat on Jan 31, 2012
Latest reply on Feb 7, 2012 by Jim Boland

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Hi people,

I am trying to create a motion study which involves the engagement and disengagement of a locking pin, which in a greater assembly enables/disables the movement of a yoke.

During the motion, which you can see in the attached video and the assy as well (check motion study named pin motion2), part number 36148 kind of slides INTO 36048. In other instances the distance mate between the two gets broken and the assembly malfunctions. This has been carrying on into the main assembly which I have been trying to create an animation for as well.

Any ideas why this might be happening?

Also, the pin retracts after it has been pushed. This is not something that I included in the motion. I don't understand why this is happening.

Bulent Kalafat Feb 6, 2012 1:18 PM

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Jim thank you very much for taking the time to investigate the problem and posting a reply. I think what you propose makes a lot of sense, and it has been a very valuable lesson for me. I will try it and see if the interference problem surfaces again, but I expect it not to.

Do you think there could have been a simpler, more professional way to create the mate between the arm and the rod?

Thanks.

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Attachments

lock assy test1.avi1.1 MB
locking.zip8.1 MB
36041_C_540_LOCK_CYL_ASSY motion.SLDASM.zip3.6 MB

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Jim Boland Feb 5, 2012 11:14 PM

I've been trying to disect the mating scheme which is where I think your problem is located. When you defined Plane1, you used a cylindrical face for the first reference. Remember from basic SW training that while you see only part of the cylinder, the modeling kernal still see the entire cylinder (kind of like minimum and maximum arc conditions in a sketch). At some point, this plane jumps to the other valid solution which causes the pin to be pushed further into the block.

I would have defined Plane1 as parallel to a plane at a point and used the center of the arm as the point. This way there would be no chance of the plane flipping to another solution.

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Bulent Kalafat @ Jim Boland on Feb 6, 2012 1:18 PM

Do you think there could have been a simpler, more professional way to create the mate between the arm and the rod?

Thanks.

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Jim Boland @ Bulent Kalafat on Feb 7, 2012 1:48 PM

I didn't see an overall problem with the mates other than the problem with the creation of Plane1. When you are planing to do an animation, you just have to keep the basics in mind. At each frame, the motion drivers have to move ahead based on time/distance/frame rate and then the mates have to be solved. If you have mates that have multiple valid solutions, you can sometimes have the driving parts move so far between frames that a mate can find the alternate solution closer and jump to that solution. So, when you have a problem like this, it is just a question of going back to basics and then logically thinking through what is happening in the solution process.

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Jim Boland Feb 5, 2012 11:14 PM
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I've been trying to disect the mating scheme which is where I think your problem is located. When you defined Plane1, you used a cylindrical face for the first reference. Remember from basic SW training that while you see only part of the cylinder, the modeling kernal still see the entire cylinder (kind of like minimum and maximum arc conditions in a sketch). At some point, this plane jumps to the other valid solution which causes the pin to be pushed further into the block.

I would have defined Plane1 as parallel to a plane at a point and used the center of the arm as the point. This way there would be no chance of the plane flipping to another solution.
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- Bulent Kalafat @ Jim Boland on Feb 6, 2012 1:18 PM
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  Correct Answer
  Jim thank you very much for taking the time to investigate the problem and posting a reply. I think what you propose makes a lot of sense, and it has been a very valuable lesson for me. I will try it and see if the interference problem surfaces again, but I expect it not to.
  
  Do you think there could have been a simpler, more professional way to create the mate between the arm and the rod?
  
  Thanks.
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  - Jim Boland @ Bulent Kalafat on Feb 7, 2012 1:48 PM
    Mark Correct
    Correct Answer
    I didn't see an overall problem with the mates other than the problem with the creation of Plane1. When you are planing to do an animation, you just have to keep the basics in mind. At each frame, the motion drivers have to move ahead based on time/distance/frame rate and then the mates have to be solved. If you have mates that have multiple valid solutions, you can sometimes have the driving parts move so far between frames that a mate can find the alternate solution closer and jump to that solution. So, when you have a problem like this, it is just a question of going back to basics and then logically thinking through what is happening in the solution process.
    Like • Show 0 Likes0
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Motion of assy causes part interference

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