BSH Bosch und Siemens Hausgeräte (Munich, Germany) has long used flexible automation to manufacture dishwashers. It was therefore only natural that the company chose to employ a battery of robots to install bitumen sound-deadening pads in its dishwasher housings, especially since the pads must be seated accurately to ensure maximum sound-proofing and a clean fit when the housings are attached to the washer chassis.
BSH uses a machine vision system and four KR 125 robots from Kuka Robotics (Clinton Township, MI) working in pairs in two separate cells. During the early stages of cell design, the company also used Kuka's KR simulation software to perform cycle time analyses and collision detection, and ensure that the robots were not being asked to function beyond their rated work envelopes.
In the first cell, the lead robot picks up a housing from a workpiece carrier and positions it in a gripper using suction. The robot then clamps the piece in the end-effector so it will be held steady during processing. Once the part is in place, the second robot picks up a bitumen pad from a stack using another suction gripper, and applies the pad to the rear panel and one side of the housing.
Because a single pad is used to insulate two sides of the housing, the robot has to bend it 90 degrees. To do this, the robot heats each pad at a predefined bending point on a centering table equipped with a series of integrated infrared heating elements. Throughout this process, the robot uses machine vision to determine the exact position of the pad before picking it up and apply it precisely to the dishwater housing.
Once the pad has been attached, the first robot sets the housing back down on its workpiece carrier, which then carries it through a furnace. The two robots in the following cell perform a series of similar operations to insulate the roof and the remaining side of the housing.
In each cell, a PC-based robot controller makes sure a pad and housing are present as the robots perform their tasks. It also notices if a robot picks up two pads instead of one. Because they are more flexible than the previous linear handling devices, the robots gently carry out process steps such as rotating and positioning without having to set the parts down between steps.
The robots have made for a much safer workplace because employees no longer have to work in close proximity of the furnace or lift the heavy housings and pads. BSH anticipates the robots will pay for themselves in less than 2 years.
For more on robotic assembly, call 586-569-2082, visit www.kukarobotics.com or eInquiry 1.
