Screw actuated robot gripper design

    Hello everyone,

    I am currently doing a project, where I have to design a screw actuated gripper with all the calculations based on the attached drawing, I have assumed that b=c=100mm and 45 degree angle. I have done calculations concerning reaction forces, support rods reactions, main screw (which length I can pick myself) and 70mm should be fine here. I calculated that the thread is Tr 8x1.5 using S235 material.

    Now for the design part. I had an idea to fix the two rods using a beam. Beam would be T shaped and it would keep the two rods fixed. I would have some kind of holder as well to hold the beam still on the left side. I would put a nut through the first bar and the motor would control the screw. I don't know if it will be possible to design it that way. Another way with the beam was to make a whole through the beam, and add a plate which will push the first bar forward (screw would be used to move the plate.

    In.

    Maybe I can just use a steel bar that will fix upper and lower part and a screw that will be longer and will go through the first bar and the fixing bar as well.

    I hope that you understand my ideas, it is pretty hard to explain it since I am not quite sure how it will work yet.

    one of the issues is that robot gripper need to be short.

    usually EOAT flange is at the side where P is shown. adding motor etc there would make the design rather long and therefore not very practical...

    but you can place stepper motor inside the gripper so that instead of P being applied from outside (compression), it is applied from inside (tension). in other words to close gripper, motor would need to pull the nut closer (green part).

    pasted-from-clipboard.png

    but there are problems... regardless of motor location.

    key issue as i see it is that if robot is not perfectly centered to pick something, one of the gripper fingers will always be closer to object than the other finger... practically every time.

    if that object is unable to move, for example it is held by a chuck or vise or another gripper or it is in a nest, then closing gripper would cause imbalance due asymmetry of the problem. and when that happens, nut will be moved vertically or try to tilt etc .... and you don't want that since this would bind the shaft etc.

    just food for thought...

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

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