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  • Hold part after adjusting part's position

    Discussion in 'The main mechanical design forum' started by phucborso1, Oct 12, 2015.

    1. phucborso1

      phucborso1 New Member

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      Hi guys,

      I am designing a machine that used for assembly line. The machine working process as following:
      1. Operator places 3 parts in a jig with locktie.
      2. robot (hexapod form PI H-811 6-Axis Miniature Hexapod ) will pick up 1st part.
      3. Camera will take a picture, then calculate positions and orientations of parts.
      4. base on results of calculation, the haxapod will move part and place that part on a hole satisfying pre-defined tolerances.
      5. the hexapod then will move to 2nd and 3rd part to do the same process as 1st part.
      6. after adjusting 3 parts, heater will heat up locktie to fix 3 parts.

      the problem here are:
      1. I need a mechanism to hold 1st part in the positions and orientations that it was adjusted, so the hexapod can move to 2nd and then 3rd.
      in the original idea, we use 3 hexapods, but it is not economic to use 3 ones (1 hexapod costs about 28k USD, then if we use 3, the machine will be expensive and our customer doesn't except that cost).
      2. so we have to design a jig to hold them, but the distance between parts are to small, like ~4mm distance between 2 adjacent parts (these parts are also small as well).

      So I ask you guys here for any idea on designing a jig like I mentioned or
      any others jigs/mechanisms that could help the machine work best.

      Sorry, I cannot attach any file because it's company confidential.

      I am looking forward for your feedback.
      thank you all
       
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    3. Dana

      Dana Well-Known Member

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      Without a picture or drawing it's going to be difficult to help. What do the parts look like? You say you place the part "on a hole", or do you mean "in" the hole? What tendency is there for the part to move after it's placed?
       
    4. phucborso1

      phucborso1 New Member

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      Thank you Dana.

      I meant IN the hole. Gravity makes parts to move because the axis of hole and axis of part (parts are cylindrical also) are in horizontal. There is a hole in the center of part and gripper will use that to pick parts, I think you shouldn't care about that for now. the parts are small, about 3.65mm square.

      Do you know any mechanism that has brakes ? I have an idea as following:I will design (or looking for if available) a manipulator that has 6DOFs (parts need to be free moved). At each joint of manipulator, I will place a brake and a motor (for initializing original position so the hexapod can pick the endeffector and then adjust). After adjustment, I will brake all manipulator's joint and hexapod will then release the endeffector, the result is the part will be held in the adjusted position.

      Correct my idea and give me better ones if possible.
       
    5. Dana

      Dana Well-Known Member

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      If the axis of the hole is horizontal shouldn't a part placed in it tend to stay put?

      If the parts stick out of the holes you might be able to use small air cylinders to press the part against the side of the hole to keep it from sliding around. But really, without a drawing or something it's impossible to picture exactly what you're trying to achieve.
       

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