Linear Bearings and Linear Rail Movement

Transcription

1 Linear Bearings and Linear Rail Movement P16603: Work Piece Movement Jonathan Sanabria April 19, 2016 Contents: Overview Assumptions for Research/Design Summary of Research Summary of Design Moving Forward Overview: The linear rails and linear bearing subsystem are to be mounted to the vertical struts. The primary function of this subsystem is to define a repeatable pathway for the workpiece movement system to move up and down with. The guide rails, when attached to the vertical struts, would create a tightly toleranced path. Then, with the linear bearings (or carriages) attached to these rails and also attached to the translating plate, the subsystem should now be constrained to move in only one axis the vertical axis. With proper foresight in the design and selection of the bearings/rails, the kinematics of the system should remain repeatable for many different cutting jobs to come. Assumptions for Research/Design: It was decided that the linear rails were to be attached to the vertical struts. This was decided since the vertical struts were already going to be in place and they could provide rigid datums for any sort of linear bearing system to be mounted on. Therefore, the only things left to define for the bearing system was the length of the linear rails, the type of carriage, the dimensions of the carriage (width, height, etc.) and any additional features that the system would contain. After some initial research, it was found that it was unlikely that any sort of linear bearing would operate that well with the slurry system. Since this was true, it was assumed that the linear bearing system would be shielding from contaminants in the local environment such as slurry and other glass particles. This made the selection of bearings easier but required some after thought for selecting proper shielding.

2 Summary of Research: The selection was relatively straightforward. A representative from a popular bearing company, Thomson Linear, was contacted some of the specifics of the project were explained to the representative. This was done in order to help solicit a professional recommendation from an applications specialist within the company. After multiple conversations in which the project was described to the applications specialist, the specialist was able to gain an understanding about what the team was trying to accomplish. For the sake of documentation, it was estimated that the maximum load (including a factor of safety) to help select the bearing would be 1000 lbs. However, since we would want to ensure long life in the bearing (with no fatigue), the bearing specialist ultimately recommended a bearing with a higher load capacity. Summary of Design: After a continuous dialogue with a bearing specialist at Thomson Linear, the following bearing carriage and linear rail were selected: Bearing Carriage Part Number: 413N30G0 Linear Rail Part Number: 421N30G +600 Y=20 These parts are part of the 400 series linear bearings, which were suggested. The 30 is the size of the rail and it was explained that the larger the rail, the higher the load capacity. For added safety, the selected 30mm rail was selected but a smaller bearing/rail could be selected if more knowledge about the cutting forces was found. The specifics of the carriage are as follows:

3 The CAD files for both the linear rails and the bearing carriages were created and put onto the CAD model for the vertical struts. These models depict how the linear rails and bearings would fit into the whole system. They can be seen as follows:

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5 Moving Forward: In order to complete the bearing system selection, the only aspect that really remains is the design and selection of proper shielding. The shielding should provide a proper housing for the bearing to hide behind to be shielded from contaminants such

6 as slurry and small pieces of glass. Some initial research was completed to look for proper shielding but was inconclusive due to time constraints on the project. The first few thoughts for shielding were a flexible rubber tube that would be able to telescope as it was stretched axially (think of how an accordion looks when pulled apart). This would provide shielding around both the bearing carriage and the linear rail as it translated up and down.