Business/industry Professionals Suggest Bearing Options
Date: 12.3.16
Location: Logan HS
The following information was sent to us from our contacts at Motion Industries, Inc. and Schaeffler Group USA, Inc. Earlier this fall the students had a conference call with Schaeffler reps to explain and trouble shoot the Exo Arm joint articulation problems. The result of that conversation is the information you see below.
For the main support bearing mounted at the top of the support leg we suggest a 2” slewing ring bearing. The slewing ring will allow 360 degree rotation and will accommodate axial and radial thrust loads. This is a low friction bearing with many balls internally. I have attached a basic drawing that Al Bower has created which shows a possible way for mounting the bearing on a stepped shaft. This part # is CSXA020-HLE.
• After much discussion regarding the bearings for the arm, we are recommending rod ends. The rod ends that we have suggested have a 25 mm bore and will connect to threaded rod. We envision the bore of the rod end being connected to a clevis which could then be connected to another rod end and rod. The rod ends will allow for some misalignment by the user, but will help to ensure that the arm stays relatively rigid while grinding. We had explored using a ball joint (as discussed during our previous call), but Schaeffler does not offer a product which we felt would meet your needs for this application. This part number, which would require 3-4 depending on if we will connect a rod end to the grinder, is # GIR25-UK. Threaded rod ends with the necessary length would need to be ordered. I believe Motion can assist with this.
• We are unsure of if you are planning on adding additional support framing around the arms or if you would just use the rod.
• Going back to our previous discussion, will you be installing a spring between the upper arm and forearm instead of an actuator? We feel this could minimize your costs/complexity and may accomplish much of what you want to do with the actuator.
• For the adjustable height feature of the exo-arm we currently recommend a round shaft system with open bearing and housing. This would make it easy to assemble. To drive it, either look into a belt system, an acme screw (of which they’d have to source elsewhere), or manual adjustment. We also discussed drilling a hole and placing a pin into the shaft to keep the height where the user would like it to be. In reviewing your initial drawing, it appears that this may have been what you were considering as well. These are part numbers TSNW16, KSO16, and KSN016.
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| First sketch of Exo Arm |
