Wizard Power automates with gantry robots

Renewable energy is on the rise in Australia, so it comes at no surprise that local manufacturers are looking for innovative automation solutions to increase production output.

Amongst them is Wizard Power, a local manufacturer of paraboloidal dish solar concentrators, who are currently developing a large-scale mirror panel manufacturing facility with a planned production capacity of more than 3000 mirror panels per day, approximately equivalent to the mirrors required for the construction of 500MWe power plant per annum.

The paraboloidal dish solar concentrators are capable of generating temperatures over 1200°C for superheating steam or powering thermo-chemical processes. The energy generated through these processes is used for electricity production, energy storage or process heat.

The mirror panels are made from glass mirrors supported on a rigid and strong sandwich panel. The combination of thin glass (about 1mm), low iron content and an optimised silver back surface in the mirrors ensures very high reflectivity (>93%), combined with the scratch resistance and durability that only glass mirrors bring. The mirrors are shaped in a custom-developed process to a high degree of accuracy to maximise the concentration of light at the focus of a dish, and hence minimise the optical and thermal losses from the receiver.

Modular design

After initial design, procurement and commissioning of the automation equipment, it is expected that the highly automated facility will be commissioned in the first half of 2011. The production equipment is modular in nature, hence rapid expansion of capacity in existing or new premises is feasible as required to meet project needs.
In addition to the modular nature of the automation solution, the company needed a system with a high degree of accuracy, guaranteeing materials handling with speed, dynamism and precision.

As part of the manufacturing process the layers of a mirror sandwich panel must be accurately stacked on a conveyor belt. After processing, the robotic materials handling solution must unload the completed mirror panels off the conveyor belt and stack them on pallets.

The cycle time requirements were 6 min per load and the system had to be able to run 24/7 with no human intervention with a footprint as small as possible.

The Güdel solution

West Heidelberg-based Andrew Engineering offered the customer an automation solution based on the modular Güdel gantry system supplied by CNC Design.

"The key to this job was that the robot had to stack the different layers for the sandwich construction on the conveyor belt with an accuracy of about +/-0.2mm," says Project Manager David Nelson, Andrew Engineering.

"But the different layers were randomly stacked on pallets, with a variation of about +/-30mm. That was the hardest part of the job on top of cycle time requirements."

The problem with a floor-mounted robot solution was not only the accuracy, but also the size of the project. "A robot solution would have been possible," Nelson explains.

"But because of the size of the project, it is quite a difficult job to do with a robot - you would have had to install a very large robot on a very large floor track, or an overhead robot, which possible but not ideal - untidy solution and would not have been cheaper."

The production area, including loading and unloading, covers an area 22m long and 8m wide. CNC Design suggested use of an automated gantry solution as offered by Güdel, a Swiss company renowned for precision systems, components, modules and robots.

Four-axis gantry robot

Together with Andrew Engineering, the two companies designed a 4-axis gantry robot with a 2m stroke and the ability to position parts with a repeatability of 0.1mm.

"Most importantly, the Güdel construction including racks, pinions, guideways and low backlash worm- and planetary gears achieves very smooth transitions,” CNC Design’s Managing Director Bruce Rowley says.

"Handling 1mm glass requires as little jerkiness as possible and the gantry solution, which is also easy to program and extendable in contrast to robots, offers quiet and very precise movements of up to 90m/min."

For Andrew Engineering, the crux of the design was to stack the layers to a high degree of accuracy within the required timeframe. Hence, the company developed a gripper which picks up each layer and measures the position on the gripper with three touch probes. The computer then calculates the exact drop-down position while the Güdel gantry system smoothly moves the precious load smoothly to the desired position.

Once the complete system is installed at the customer’s new production facility, it will be used for the production of mirror panels with a capability to run 24/7 with no human intervention and only automatically stops when it runs out of product.

Results:

Andrew Engineering and CNC Design developed a precise, economical and expandable automation solution for its customer for their planned 24/7 fully automated production line.

Project Management: Andrew Engineering Pty Ltd, West Heidelberg, VIC
Task: Automation solution covering an area of 22m x 8m, cycle time 6min to place mirror materials on conveyor belts for processing into a panel and then unloading the finished panels onto pallets,
Requirements: Positioning accuracy +/-0.2mm, smooth transitions, speed to meet required cycle times, high repeatability, expandable and modular system, small footprint
Outcome: Güdel 3-axis gantry turnkey solution plus a custom designed gripper system, guaranteeing high accuracy, improved safety and easier programming in contrast to robot solutions.
CNC Design is the Australian Distributor for Gudel gantry systems and rack and pinion components.