156B Week 6

Overview of Status of Analysis, Design, Fabrication, Tests, etc.

Analysis:

• • So far, the bulk of the analysis has been applied to the feeder mechanism to ensure the Nafion can be effectively removed from the supply spool. To that end, the following FBD of the feeder mechanism was drawn:

• • The unknowns in this FBD are the coefficient of friction (which is wrapped up in the frictional force), the unwinding Tension (Tunwind). To that end, experiments were conducted and are outlined in previous progress updates. Through this analysis, we were able to determine a proper spring constant and displacement for the spring force, and the parts were ordered.

  • Additional analysis was given to the length tracking functional requirement of the system. For the first pass, the length was tracked at the take-up spool. 

    • In order to track the length at the take-up spool, a model was developed as follows:

• • It can be seen that effective radius of spooled tubing changes with the number of wraps around the take-up spool. This model was implemented in the previous weeks progress report and the extrapolated error was determined to be just at the bound of the requirement. This is promising, but would like to look into length tracking at the feeder mechanism assuming no-slip. 

Design

• • The current design is illustrated with the following figure:

• The design includes the following main subcomponents:

  • Feeder Mechanism:

    • This is outlined in previous progress reports, and is shown below in last weeks accomplishments

    • Tension Monitoring:

      • This is the part of the diagram that includes the two 90 degree idler pulleys with a force transducer between them

    • Spooling Guide:

      • A servo controlled spooling guide to ensure uniform wrapping of the tubing

  • The design of this will be better explained in the proof of concept presentation on May 7, 2019. 

Fabrication

• • Current fabrication is up to the prototype developed for the proof of concept presentation scheduled for May 7, 2019. 

    • This prototype encompasses the supply spool, feeder mechanism, stationary spooling guide, and the take-up spool

    • Need to fabricate the tension control idler pulleys and incorporate

Tests

• • Test on current prototype was implemented and outlined in accomplishments from previous week. 

  • Prototype Test:

    • Expected outcomes:

      • Determine feasibility of just using PP rollers with no friction material added as the feeder mechanism

      • Determine the need for tension monitoring on the take-up side of the tubing.

Accomplishments from Previous Week

• • The main accomplishment from the previous week was the prototype of the feeder mechanism developed to demonstrate the feasibility of the design:

• The prototype was fabricated using the following:

  • Base: 1/2" acrylic sheet with mounting holes

  • Side mounts: 1/4" acrylic mounts to secure rollers

  • L-brackets: To secure the side mounts to the base

  • PP Rollers: two 4" PP rollers with surfaced contact area

  • DC geared motor: to drive lower roller

  • Springs: Mcmaster Springs with k = 2.5 lbf/in with with range of 0.3-3.29 lbf

  • Spooling Guide: Stationary spooling guide that was 3D printed

  • 3D Printed take-up spool: Scaled take-up spool driven by motor

  • DC geared motor 2: drive take-up spool

    • Microprocessor w/ motor driver: To drive system

  • Results of the prototype and testing:

    • This prototype demonstrated that this feeder mechanism supplies enough force with just PP rollers to drive the spooling process. 

    • The initial testing was just done where the take-up spool and feeder mechanism run at the same linear velocity for the tubing, with an initial delay to allow for tension reduction past the feeder mechanism. 

    • Will need to incorporate the tension monitoring system after the feeder mechanism to better control the tension on take-up. 

    • Additional notes:

      • Need to derive motor torque relation to friction to better spec a DC geared motor. 

    • What was not accomplished this week with the prototype:

      • Did not test length tracking at the feeder mechanism yet, will test ASAP.

  • Completed the first draft of the report and the webpage by Friday of last week.

Goals for Next Week (list names after each item). Use specific and measurable objectives.

• • Tension Monitoring System 

    • To develop and begin fabrication on pulley system to be used in tension monitoring section of spooler (Jhon and Iman)

    • Contact companies and spec transducers to use in system (Patrick and Anthony)

    • Determine tension that we want the take-up spool to be wrapped with (Patrick and Anthony)

  • Feeder Mechanism

    • Begin final design and fabrication on feeder mechanism (Jhon and Iman)

    • Determine torque/speed requirements to purchase new motor (Patrick)

    • Check on quality assurance of PP used in final design (Iman)

  • Length Tracking

    • Test length tracking at feeder mechanism (Anthony)

    • Determine best place to track the length based on previous experiments (Anthony and Patrick)

  • Control algorithm

    • Ed Pogue reached out to help with control portion of the spooling system. Scheduled meeting with Ed (Thursday Afternoon) to discuss control of the system. (Team)

    • After discussion with Ed, will begin control design and implementation (Patrick and Anthony)

  • Take-up Spool:

    • This needs to be finalized this week to incorporate into design (Iman)

  • Spooling Guide:

    • Spec/Purchase servo and install into current prototype of spooling guide (Jhon and Anthony)

    • Machine PP spooling guide, [may need to order more PP] (Iman)

  • Horizontal mounting

    • Finalize mounting design ideas for horizontal axis mounting of the supply and take-up spool. (Patrick and Jhon)

Sponsor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)

• • Sponsor is currently okay with the feeder mechanism, and is much happier that we are only going to employ use of PP.

  • Sponsor will handle decontamination of the system at their site:

    • Indicated they would prefer it assembled, with assembly instructions, to disassemble themselves and decontaminate for installation in clean room. 

Instructor Comments from Last Meeting and Actions Taken to Address these Comments  (indicate date of comments and if via email or in person)

• • Must consider all limitations of system within meeting the cleanroom ISO Class 6 (1000 ppb) which includes:

    • Cleaning with IPA

    • NO lubrication in the bearings: (must look into dry bearings/bushings or other alternatives)

  • Suggested looking into drag loops 

    • Will look into this in coordination with tension monitoring this week following the POC presentation

  • Believes feedback on the feeder will be a better solution for the system.

    • Will allow for constant uptake speed, explained this idea with the drag loop and how old film reels work

  • Wanted folders added to reports page: (Done.)

Comments from Other Students in the Class (indicate date of comments and if via email or in person)

• • Not applicable yet. Will update after POC presentation on May 7, 2019. 

Risks and Areas of Concern

• • The following areas have been determined to be high risk to the final system:

    • Feeder Mechanism:

      • This seems to work fine right now, but need to quantify that it is not damaging the material. 

    • Tension monitoring:

      • Need to understand this better, and determine cost of these transducers. They may be expensive and take a while to ship.

  • Areas of Concern:

    • The control implementation is of slight concern, but meeting with Ed Pogue this week to finalize a design and begin implementation. 

Resources or Information Required but not Available

• • N/A

Schedule

• • Milestones:

    • May 17th: Implement spooling guide and tension monitoring into prototype with control

    • Week 8: Hardware Demo is week 9, so prototype needs to be completed by this time

    • Week 9: Hardware demo

    • Week 10: Final Design Review with sponsor

  • Gantt Chart:

    • Updated to current Gantt chart

Budget (list amount spent and amount remaining)

Progress on Report and Webpage

• • The front page of the webpage has been somewhat accomplished. Need to figure out how to use html better to make a better webpage.

  • Report was submitted at 50% to David Gillet on Friday of last week. Received comments from instructor, and will begin second draft of report this week.