Masters Theses

Date of Award

5-1995

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

Frank H. Speckhart

Committee Members

Edward Clark, Clement Wilson

Abstract

The translation system has been developed as a test-bed to perform parting-line removal experiments on Saturn's plastic fenders. This project will be combined with sanding and cutting tool end-effectors in an effort to produce a fast and reliable parting-line removal method.

Since the fender parting-line represents a complex trajectory, a guidance system was developed that follows the parting-ling based on the fender itself. The top of the fender acts as the template by which two specialized guide wheels follow its path. The forces exerted against these wheels are translated through a linear rail system which selectively restricts some motions while allowing other motion the freedom to follow the fender.

As the guide car follows the complex trajectory it is important that the end-effector maintains a constant force with the parting-line so that it finishes the surface consistently. Force control is achieved by attaching the end-effector to a compliant air cylinder. Through preset pressure levels, this air cylinder maintains forces between the fender and the end-effector. In addition, it can be set to add or subtract the downward force of the end-effector; therefore, allowing for precise and variable control between the end-effector and fender.

The force compliant guidance system and end-effector attachment system is a very economical approach while also maintaining the robustness required in an assembly environment. Given these features, a wide variety of end-effectors can be attached and used to develop the best method for removing the parting-line.

The proto-type translation system has the ability to traverse 91% of the fender in 30 seconds (a speed of 4 in/sec). The effectiveness of the sander or cutting tool varies when the translator is operated at full speed, therefore, the system is slowed down according to the needs of a particular end-effector. Test results have shown that the cutting tool can perform its desired cut while moving at 1 in/sec. Similarly the sander can be operated at 0.25 in/sec and the desired fender profile is obtained. The proposed final system will use these two methods in sequence to successfully remove the fender parting-line.

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