Case Studies Of Industrial Robots

Robots in action can be found everywhere. Robot Manufacturers give examples of robot applications in different industries.

Kawasaki, Germany - IFR Partner

Everything flows: Robot application in the present-day pane production

September 2012

Equipment for cutting and conveying in the float glass process is the object of HEGLA GmbH & Co. KG. The combination with Kawasaki Robotics models for handling purposes delivers an interesting result.

Glass panes nowadays are usually produced in the form of 'float glass', which offers the advantage of an extremely flat surface and nearly no inclusions of air. In a continuous process, the lightweight molten mass with a temperature of 1100°C is directed onto a zinc bath (232°), where it goes on slipping until the solidification point is reached.

On its way, the glass passes a leer. During that phase of the process, the most important criterion is the absence of mechanical stress. The zone of introduction is called the warm end, the annealed zone the cold end. Finally the pane is tested and cut to the required dimensions. After the first cut, the size still amounts to 6000 x 3210 mm, the thickness ranges from less than 1 mm to 24 mm.

Since all of the process conditions are known for a long time, this method usually does not entail major problems. Reliable equipment however is always required.

HEGLA is specialized in machines to be used for cutting and transportation of the material behind the cold end, and KAWASAKI robots are responsible for removing the panes from the plant. Both companies have joined forces for a project of Cardinal, an American float glass producer.

The concerned plant disposes of several lateral extraction points, equipped with cutting machines and crushers. Handling procedures in these lateral arms is carried out by two Kawasaki ZX165U robots each. The moving panes are seized by means of geo grippers and vacuum technology, and then carefully stacked onto L-stands. These stands are rotatable through 180° and therefore can be exchanged in the running process, too. The sequence as a whole is optimized with respect to perfect continuity.

Kawasaki ZX165U stacking a pane

Kawasaki ZX165U combing and drawing
a
pane through the belt

"For many applications, we are forced to grasp the pane only from the bottom side", explains Stefan Reuter, the head of the HEGLA engineering team. "For subsequent coating or other treatment, the upper surface must remain free from any contamination. Therefore it is necessary to aspirate the pane through a gap in the conveying belt. Then we have to comb it from the bottom, which is not easy, and lift it from the plant."

In order to be able to remove the pane in the running process, the speed of the robot must match the belt speed. Therefore the Kawasaki ZX 165U is equipped with a particular option, the ?Conveyor Tracking?, which ensures for a completely synchronized movement. This way the pane can be drawn off without being damaged. Then the robot quits the extraction zone.

The 'Conveyor Tracking' option includes an encoder to detect the belt speed, as well as a sensor for the position of the moving pane. Both parameters are transferred to the robot control, so that the combing and the removing procedure can precisely be adjusted. The resulting function, extraction 'on the flow', is an in-house development of the HEGLA company.

Already before, the panes are oriented in the correct sense, and the robot always receives unambiguous data for handling. When stacking onto the stand, the robot approaches a definite edge of the pane and pushes it into the required position, so that the defined orientation remains unchanged. This procedure is supported by an integrated stacking edge at the gripper, used as a reference. 

Pane dimensions vary between 500x500 mm and 2450x1850 mm, at a thickness of 2.2 to 6 mm and a weight between 1.4 and 70 kg. Nevertheless two gripper variants are enough to handle the items, automatically to be changed. Resulting cycle time is 12 to 18 sec., which depends on the size in question.

A crucial point is the permanently changing weight, which (including gripper) sometimes may attain the maximum admissible load. Kawasaki engineers have found a sophisticated solution: The concerned ZX165U model is offered in two variants, one for 165 and one for 200 kg load, originally with distinct ramp and speed parameters. Here the control has been modified, so both parameter groups are available at the same time. The selection takes place automatically, according to the situation. This method optimizes the cycle time and reduces wear.

In practice, size and weight of panes would allow for manual execution only with difficulty, since the entire method is coupled to a constant flow - even without considering the risk of damages and accidents! A theoretical value of 1 to 2 employees per shift with appropriate handling equipment delivers a payout time of only 2 to 3 years. The two Kawasaki ZX165U robots therefore prove to be a meaningful investment in that application, too. 

 

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