Composite sandwich robot structure for handling LCD glass panels

Abstract

Industrial robots are indispensable elements to accomplish the factory automation which is a final goal of most industries. However, most industrial robots have been employed only in simple processes such as welding, painting, assembly and transfer operation because of their economical inefficiency such as small payload with massive body structure and inaccuracy in assembling operation. For the industrial robots to play more important roles in future factories, the robot structures should be lighter than current one without compromising stiffness. The industrial robots are employed increasingly in glass panel display manufacturing in clean room environments to eliminate contamination from human workers. The robots with double arm type structures are favored by glass panel display manufacturers because of productivity improvement. The double arm type robots have two arms, wrists and hands. The two wrists have different configurations to avoid interference when moving back and forth. To meet the handling capabilities for large glass displays, the robot hands and wrists are increased in size to have high stiffness and to reduce the deflection of robot structure due to both the weight of glass panel display and the dead weight of robot structure. The increase of robot size requires large working space and large motor power, which degrades the accuracy and speed due to the inertial effect from large dead weight. The problem of weight increase of robot with higher stiffness can be easily solved if carbon fiber epoxy composite material is used for robot structures because currently developed high stiffness carbon fiber epoxy composite material has about eight times high specific stiffness compared to that of conventional metals such as aluminum or steel. Carbon fiber epoxy composite materials have also high specific strength (strength/density), and the structures made of carbon fiber epoxy composite materials are much stable because they have high damping as well as a...