Innovative Conceptual Design

This chapter describes low cost and flexibility as two key requirements in the design of a new drive system for a mechanical indexer. Need analysis helps to generate two key insights into the design task. Based on these two insights, two competing designs are developed using the parameter analysis methodology to address the requirements. A detailed discussion of technical issues involved in realizing these concepts is presented. Both of the designs were built and tested for performance.

The Initial Need

Indexing systems are often used in industry to incrementally move products along an automated line and stop them at predetermined workstations. At these workstations, people or machines perform assigned tasks, such as welding or assembly of components. Two common technologies for producing incremental motion are servo drives and mechanical indexers. Servo drives employ a dc motor, speed reducer, clutch–brake system, sensors, and electrical controls. They are highly flexible in the sense that they can accommodate changes in the product line by adjusting the timing sequence for various activities. In contrast, mechanical indexers constitute rigid automation. They use a continuously running electric motor, speed reducer, clutch–brake system, and indexer unit. The indexer unit converts the constant input motion of the electric motor into intermittent output motion (linear or rotary) by using a cam–follower mechanism. Both of these indexing technologies are expensive.

Market research has indicated that there is a need for flexible, yet moderately priced, indexing systems.