New carousel-robot combo for manufacturing cells.
While discussion runs on about the technical development of vision and tactile sensing in robotics, Prab Conveyors Inc, a division of Prab Robots Inc, Kalamazoo, MI, has applied existing technology to the job of organizing and sorting small parts for automated manufacturing. The result is a compact unit providing large storage capacity in a very small space.
Applicable to a wide range of parts having a similar basic shape, Prab's "robot feeder' can literally be the beginning and the end of a very flexible manufacturing system.
Consisting of a carousel with a programmable robot arm mounted on its central shaft, the unit accepts small parts on columns, indes them to a loading position, and orients them for machining. When the several steps of the process are completed, the unit returns the finished parts to the load/unload station.
The one-man operation, serving complete manufacturing cells, is simply controlled and very precise, and is built around off-the-shelf components. This feature leads to a relatively low initial cost and easy maintenance.
Most parts of the complete system are familiar to plant personnel. When repair or replacement is needed, the components are available through normal supply channels.
The application illustrated also allows for a considerable variety of parts. Inside diameters and part thickness can vary widely as long as the basic shape allows the parts to be stacked on one of the carousel's columns.
How it works
Raw parts, delivered by conveyor or tote bin, are manually stacked on a column at the input station. Due to the holding capacity of the six columns, this manual service is infrequent and can be performed by personnel assigned to some other primary task. One robot feeder system holds a four-hour supply of parts.
The unit indexes a loaded column to a position under the robot arm and raises the stack to gripping position. There the two-axis robot arm picks up a single part, extends, and places the part on the Prab-designed orienter.
Depending on the application, this orientation can be keyed to any identifiable surface feature of the part: a boss, an indentation etc. The unit can also be equipped as a primary gaging station, measuring ID, OD, or part thickness.
Any one of Prab's 13 robot models can then be used to pick up the part and feed it into subsequent production steps. The choice of robots used (in the photo, a Model 4200) can be made on the basis of required speed, part weight, reach, and number of axes required.
Indexing of the carousel is accomplished by a hydraulic motor and a pinion and ring-gear train capable of handling heavy loads. Hard stops ensure accurate positioning, while deceleration circuits cushion the shock of mechanical positioning. The result is very gentle handling, which can be important in precision parts production.
Elevators at each station operate on ball screws driven by hydraulic motors and controlled position sensors. These bring parts to gripping position on demand.
Solid-state controllers, relay controllers, or customer-specified controllers are all available for the system. Complete manufacturing cells, including the robot-feeder, can also be integrated into a central computerized control system.
For details, circle E49.
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|Title Annotation:||Prab Conveyors Inc.|
|Publication:||Tooling & Production|
|Date:||Jan 1, 1984|
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