Argo-Hytos uses SCARA robots to automate test station for valves
Renowned hydraulics specialist Argo-Hytos commissioned system integrator Resim to design and build a fully automated system for the production of electromagnetic valves. High-precision SCARA robots from St?ubli perform all of the handling operations, the most challenging of which comes with the screwing and unscrewing of the valves at an end-of-line test station.
Argo-Hytos set automation partner and system integrator Resim the clearly defined task of automating to the maximum extent a previously manual production line for electromagnetic valves at its plant in the Czech Republic.
In planning the project, the Resim team of designers was not only able to draw on the experience gained from the company’s long and successful collaboration with Argo-Hytos, but also on the expertise they had acquired over 30 years of industrial automation. An essential component of this know-how has been the recognition that, when precision and speed are the main criteria, St?ubli robots are the first choice.
In this case, four TS2-80 SCARA robots take on the handling of the electromagnetic control valves during assembly and subsequent end-of-line testing. There are several good reasons for this. With a TS2-80, the system integrator can theoretically perform up to 200 gripping operations per minute. This corresponds to a cycle time of 0.33 seconds while maintaining high precision: Repeat accuracies of up to ± 0.004 mm in the Z-axis are possible for pick and place.
The robots in the new assembly line supplied by Argo-Hytos do not have to work to quite that degree of accuracy, but the demands in terms of precision are nonetheless high. After all, the valves are pressurized to several 100 bars when in operation. The assembly of the individual components and especially the seals must be correspondingly precise.
Challenge: Automated valve testing
Automating the end-of-line test station proved to be particularly challenging at the project planning stage. Argo-Hytos developed its own testing device for this task, and this is where an unexpected obstacle arose. Screwing the valves into the test station caused no problems for the TS2-80. When unscrewing, however, the final turn on the thread occasionally jammed, bringing the test station to a standstill.
Solution: Force measurement on the fourth robot axis
The experienced Resim designers were soon able to solve this problem by bringing into play the design feature of St?ubli robots that permits integrated force measurement – without external sensors – on all four axes. In this specific case, the force is measured on the fourth axis, which allows the system’s control unit to recognize whether the valve is turning freely in the internal thread of the test unit. If the measured force increases, the obstruction can be overcome by briefly reversing the rotary movement. If necessary, the process can be repeated several times.
This ensures that the valve does not jam and the system does not come to an unplanned stop. The great advantage here is that the force measurement function is integrated into the drive system and therefore no external sensors are required.
Conclusion: Good collaboration leads to a successful project outcome
From the point of view of all those involved, the collaboration between St?ubli, Argo-Hytos and Resim on this project was highly productive and goal-oriented. The production line was up and running in spring of 2022 and, more than two years later, it is still working just as efficiently as the day it was first installed. Argo-Hytos has achieved its objective of fully automating the complex final assembly process of electromagnetic hydraulic valves. The valves meet the highest quality requirements, and the St?ubli team is proud to be part of this successful collaboration, which will certainly not be the last of its kind.
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Text by: Industrie Kommunikation H?gel
About St?ubli Robotics
St?ubli Robotics is a leading global player in robotics, consistently delivering engineering as effective and reliable as our service and support. A complete solutions provider for digitally networked production, St?ubli offers a broad range of 4- and 6-axis robots including robotic arms designed specifically for sensitive environments, autonomous mobile robots, driver-less transport systems (AGVs) and cobots for human-robot collaboration.
About ARGO-HYTOS
The ARGO-HYTOS Group, held by the ARGO-HYTOS Group AG, is an innovative, medium-sized group of companies. With around 1,600 employees at six production sites in Germany, the Czech Republic, India, Poland and China, it develops and produces standard components and intelligent system solutions for fluid technology. The group operates several own sales companies in Europe, North and South America and Asia. The company has developed into one of the international market leaders, particularly in the field of mobile hydraulics. The ARGO-HYTOS Group AG is the operational management unit of the group.