Machine loading with robots

A major growth area for industrial robot applications is that of automatic machine loading. Wherever there is a production machine that is ‘operator-paced’ or a grouping of two or more machine tools in a process, there is an opportunity for improvement using robots in the form of reduced direct labor costs, increased output from the machine or machines, better or more consistent quality of parts and improved capital equipment utilization.

The robots are used to load position and then unload and transfer work pieces. Even fully automated transfer lines are candidates for robot loading. In one of the typical applications, productivity has become 25% better than it was with manual handling. Equally important, the operator is now free to check and change tooling, watch automated gauging stations, and make necessary periodic adjustments.

Known as PUMA (Programmable Universal Manipulator for Assembly), a light-weight and high precise industrial robot has been developed to operate on an assembly line side by side with human workers. The robot position objects to an accuracy of 0.004 in (0.1mm). It has five axes of motion corresponding to the human being’s waist, shoulder and elbow rotation, wrist bend and hand rotation. Its load capacity is 7.7 lb (3.5kgs). Microprocessor controlled electric servos position the arm of the PUMA robot. The robot is taught a program by either a teach module or computer terminal.

Other interesting development in field of mechanical handling has been “Pick-and-place� units and “Air-film transporter system.�

Two economically priced, pneumatic transfer arms, designed to automate a wide range of routine ‘pick-and-place’ production operations are now available. Both are capable of automating such labor intensive operations as the selection of small to medium sized components and positioning them accurately on jigs, fixtures, drilling tables, presses, conveyors etc.

The larger unit, which can hold components up to 3.5kgs provides five base movement clamping; horizontal extension up to 250mm; lifting up to 50mm; swinging up to 120 deg; and rotation of the jaws through a maximum of 180deg

The smaller arm has a maximum working load of 0.5kg and three movements clamping lifting up to 25 mm and swinging through 180 deg. Maximum.

Both are powered by integral pneumatic actuators working from a standard factory air supply at 5.52 Bar (80 lb/in). The speed of movement can be adjusted by fitting restrictors to the control valves.

Air-film systems have been widely used in the United States for about 20years. The system operates off a factory compressed air supply by creating a thin film of air between the factory floor and compliant inflated diaphragms which are built into transporters or sets of individual air stakes. Once floating on air the load can be moved with very little effort with equal ease in any direction.