CASE DUUN INDUSTRIES
massive welding station
Duun Industries is manufacturing auxiliary equipment for tractors, like snow blowers, firewood processors, flail mowers and slurry handling pumps. The company invested in a large robot welding system in 2013. A robot gantry has two Yaskawa robots mounted both in 3 axis XYZ-portals. The welded components are placed in the robot cell in two-axis positioners. This results in 11 servo controlled axis for each of the two robot systems. The robot installation is the biggest in Norway and also one of the biggest in Nordics.
Besides the big gantry station there is also a smaller robot station for welding a variety of smaller components for bigger assemblies.
Picture: A Yaskawa welding robot at Duun Industries.
Offline programming at DUUN Industries
Robot welding is used not only to achieve good productivity but also to guarantee constant and high quality welds. Ramp-up time is critical. Many of the products have seasonal sales peaks. This means that the new products have to be on market at the right time. Programming the robots offline ensures that the welding robots are in effective use and ready for welding when needed. There is no time for non-value adding work, like programming by teaching.
Cell calibration without external measuring devices
Before starting to use offline programming, the software has to be commissioned with the real system. The major task is called cell calibration. This means the deviations between the real robot cell and the simulation model of the robot cell have to be compensated. There are two steps: First the real robot cell with all periphery equipment has to be measured, and secondly, the simulation model has to be calibrated using the measuring data. Delfoi ARC offline programming software doesn’t require any external measuring devices for the measurements, like Leica laser tracker or similar. The software utilizes the welding robots as measuring devices. This is a very cost-effective and also accurate way of measuring. At Duun the accuracy after calibration was only +/- 5 mm despite the size of the station and the amount of servo-controlled axis.
No production stoppages thanks to offline programming
Duun Industries is designing all of their parts and equipment using a modern 3D CAD system. Models created with Inventor software include all information needed for offline programming. The Delfoi ARC software utilizes the CAD features like part edges, curves, splines and e.g. holes effectively. Not only the welding paths are programmed offline but also the seam searches. Searching is needed to eliminate the remaining small errors after calibration. And cell calibration can’t eliminate the welding heat distortions. By utilizing seam searching effectively, the small deviations between the real cell and the simulation model are eliminated. At Duun, the welding programs are taken into operation without any production stoppages.
Quality of products is constant
The company has high quality standards. This goes also for welding. Most of the welding seams do not require additional grinding operations. One of the reasons for this is offline programming. OLP guarantees controlled manipulation of wire length and torch angles. These are set in templates and in WPS. When teaching a robot online, the quality of welds is dependent not only on correct welding parameters but also on how accurately an operator can manually teach each welding point. It is normal that the length of wire as well as the torch angle vary. When using OLP, the wire length and torch angles are always constant as the values are based on CAD features. Once an operator has fine-tuned a robot program for highest quality, he will store the parameters in the software's Welding Procedure System database, WPS. This guarantees that the stored values will be re-used independently of who will create a program when creating a new similar weld.
Skillful people are of great value
Programming efficiency or high welding quality are not only achieved because of the software. There are always people behind the work. The software users at Duun know what to do. They work as the team and share experiences and know-how between each other and the software constantly. WPS and templates are created by the operators, and they maintain and update the information.
Picture: Robot operators at DUUN.
Duun develops, designs and manufactures all its products in Åsen in Trøndelag Norway. The company distributes products via chosen dealers and their respective network. More than 60 years of experience combined with modern technology and market knowledge give background for optimal products. Their range of products is presented in detail in their catalogue and they have developed various support functions for their dealers and customers.
Duun Industries tries very hard to support both new and seasoned customers by updating and keeping technical information like manuals and part lists available. Their motto is to make ordinary things unusually well through continuous improvement. Duun Industries also appreciates having suggestions for improvements as a vital part in this never ending process.
More information: DUUN Industries