RASIRC Auto-Tensioning Spooler

Project Background

Company

    RASIRC is a San Diego based company that provides dynamic gas generation with applications in semiconductor, pharmaceutical, medical, biological, fuel cell, and power industries. Their products include gasses such as water vapor, ultra-pure peroxide, and ultra-dry hydrazine. The company was founded by Jeff Spiegelman.

Project

    The generation of one of RASIRC's specialty gasses involves the use of Nafion tubing. Nafion is a brand name sulfonated tetrafluroethylene based fluropolymer-copolymer and is used as a semi-permeable membrane. RASIRC purchases the Nafion tubing in increments of 1000 ft wound on a spool. For their applications, the tubing must be transferred in increments of approximately 150 ft to a secondary spool. This process is currently done by an onsite quality engineer, who manually transfers the tubing by hand in a cleanroom. The company is interested in automating this process in a step towards automating this entire specific gas generation process. The automated system must be incorporated into the cleanroom workspace, and must not mechanically damage or chemically react with the tubing. In addition, the consistency in length of the transferred tubing was subjected to large variation when done manually, and the company would like the automated system to minimize this inconsistency to within an agreed upon error. 

Objectives

Final Design

    The system features a freely rotating supply spool, a motor-driven pinch-roller “system” which peels the Nafion off the supply spool, a set of idler pulleys and load cells arranged to estimate the tension in the Nafion once it passes through the pinch-rollers, a servo-driven tubing guide used to wrap the material on the take-up spool uniformly, and a motor driven take-up spool. The take-up spool is velocity controlled, with the angular velocity modulated based on the tension estimated by the load cells. This is to ensure the material isn’t wrapped too tightly on the take-up spool and the Nafion doesn’t experience a large tension that mechanically damages it. The take-up spool also features a locking pin-based cap which can be removed to allow the system operator to remove the wrapped material once the desired length of tubing has been transferred. The whole system is set up to be operated using a simple user interface based on an LCD status screen, a set of buttons, a master power switch, and a set of lights and buzzers for alarming.

Performance Results