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AIA: Robots Form Basis of Workcells

Over the past quarter century, automotive component manufacturer Bosch Group (Stuttgart, Germany) has manufactured approximately 100 million antilock braking systems (ABS). The company also produces a number of related systems, like its antislip control (ASC), electronic stability program (ESP) and electrohydraulic braking (EHB) products. Bosch assembles these systems around the world, in countries like France, the United States, Australia, Japan and China. By doing so the company ensures its products are manufactured close to customers.

During the past 3 years, Bosch has begun creating production lines in these disparate plants using a standardized, module-based component system. In each line, up to 30 independently operating cells with as many as 20 structurally identical six-axis robots from Stäubli Corp. (Faverges, France) perform numerous assembly and feeding operations. The flexibility of the component system is such that it can be used to configure production lines for all generations of ABS, TCS and ESP systems, as well as EHB systems.

Currently, 11 of these production lines have been put into service throughout the world, employing 200 Stäubli RX60 and RX90 robots. Bosch predicts it will implement 11 or more additional lines in the coming years.

"The prerequisite for internationally uniform production lines for the new ABS generations was being able to build standardized systems economically and very quickly," says Bosch engineer Ulrich Reichart. "The objective was maximum flexibility with regard to product types and variants within a single generation, as well as with regard to interchangeability and reuse of system modules, in order to minimize engineering and training expenses for system redeployments."

As part of this development, Bosch chose to go with six-axis robots exclusively, as opposed to mixing and matching different types of robots to the application.

"In contrast to previous generations, the new product generation requires at least five axes for approximately half of all the operations. That means there's no point in using an "improvised" solution cobbled together from linear systems or SCARA robots with supplementary axes," says Thomas Huber, project manager for the standardization group. "Our analyses showed that standardized six-axis modules represented an economical, general-purpose solution, including the reusability aspect."

As a result, except for a few select cases in which an existing, refurbished SCARA has been put to work, Bosch is using six-axis robots in all of its cells, no matter if the task is pressing, bolting or a pick-and-place operation.

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Each production cell operates independently and has its own controller. The systems are linked together according to the modular needs of the line. The robot controllers, also from Stäubli, communicate via Ethernet using IP protocols.

Driving to a few points is generally sufficient for teaching the motions. All other positions are computed and stored in the associated robot controller. This makes it easy to extend production to a large variety of models and variants. It's also relatively easy to implement short-term product modifications to meet customer wishes or reconfigure from one ABS product to another one.

"This flexibility within the cells is important to us, since within a single ABS generation...it may be necessary for a robot to handle four different bores on three different faces, depending on the ABS type," says Bosch group leader for equipment machinery and design Jochen Schnau. "Product modifications don't cause us many headaches."

For more information on robotic assembly, call 864-433-1980, visit www.staublirobotics.com or eInquiry 2.