Hello All, I am currently pulling my hair out over a design for automatically pushing a rubber grommet into a hole! does anyone have any ideas or concepts of tool heads that could perform this operation?? Holes size is ø15.5mm Grommet outside dia = ø23.5mm width = 13mm inside Dia =ø12 Thanks.
Hi, Perhaps something similar in concept to an automotive tyre beader? I'm assuming the grommet has an annular groove that allows it to locate? In my experience, it's always better to pull a rubber grommet whenever possible, as opposed to pushing - that way you avoid compression and expansion. With the dimensions you've given, that's quite a lot of compression that the grommet has to undergo, so whatever you do, I'd certainly not attempt it in one linear motion - the tool should be uneven and rotate, with a guide like on a tyre beader. That would be my first attempt.
What about something along the lines of an seal installation tool (used in assembling hydraulic cylinders). I looked for a video but found the original patent for the tool http://www.google.com/patents/US4091521. I think the pictures do a decent job of showing how the tool is used. From my experience they take some finesse to use but adding some features (ridges) to the tool end, that mate with the grommet profile, might keep the grommet in position and make automation more reliable. Another idea more along Kiss's approach is to press the grommet through tool with a tapered hole. Similarly i would recommend a rocking motion as to not push the entire grommet at once. I am picturing something that functions like an orbital riveting tool. However unless there is sufficient stiffness in the flanged top and bottom of the grommet this approach probably has little chance of success. One last thought you can often warm or cool the rubber to change its stiffness, which may help whatever process you use.
I have done something in the past. It all depends on a couple of things, The most important is the durometer of the rubber. If you can picture this tooling 1)You place the grommet in a blind hole with a pin in it. 2)Pins slide in to squeeze the groove to a size smaller that the hole 3)The pins then rotate 90 degrees to straighten the groove parallel to the hole. This is were the durometer is important as not to rip the rubber when folding half the grommet up 4) Now you grommet is compressed smaller than the hole. 5)If this was automatic, move slide forward, release pins and retract. This tool took some development all based on the rubber, but it will work
What is the durometer of the material? If it is squishy enough, you could make a thin sheet cylindrical form to load one side in. Then push that into the hole and pull. Kind of like loading a one way clutch into a transmission, but the form goes all the way through. It looks like there is plenty of room between the ID of your part and the ID of the hole to get this to work. I am assuming the wall thickness of the grommet is around 2-3mm. This could also be easily automated with a robot once you get the idea tweaked in.
Hi! Since I designed some various appliances for rubber parts assembling, I'd like to see your "grommet" and then I could see if something matches to your profile. Best regards!
