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The production of electromagnetic valves was to be fully automated, partly due to a lack of personnel. An experienced system integrator built a process reliable system for this purpose, in which four high-precision Stäubli SCARA robots take on demanding tasks.
Hydraulics specialist Argo-Hytos relies on full automation for the production of electromagnetic valves. The valves are handled by high-precision SCARA robots from Stäubli, which also perform demanding tasks such as screwing and unscrewing the valves in an end-of-line testing station.
The task that Argo-Hytos gave automation partner and system integrator Resim was clearly defined: to automate, as much as possible, a previously manual production line for electromagnetic valves at its Czech plant. Resim was not only able to draw on the experience gained from its long cooperation with Argo-Hytos in project planning, but also on the know-how gained from its 30 years in industrial automation. Part of this know-how is the knowledge that when it comes to high precision and speed, Stäubli robots are the first choice.
Four TS2-80 SCARA robots are used to handle the electromagnetic control valves during assembly and subsequent end-of-line testing. There are several good reasons for this. The system integrator can theoretically implement up to 200 gripping processes per minute with a TS2-80. This corresponds to a cycle time of 0.33 seconds – with high precision: Repeat accuracies of up to +/- 0.004 mm in the Z-axis are possible with pick and place.
The robots in the new Argo-Hytos assembly line do not have to work quite that precisely, but the demands on precision are high. After all, the valves are pressurized to several 100 bar during operation. Likewise, the assembly of the individual components, particularly the seals, must be precise.
Automating the end-of-line testing station proved especially challenging. The last thread of the valves occasionally jammed when unscrewing, bringing the system to a standstill. The solution involved integrating force measurements on all four axes of the Stäubli robots. In this case, the force is measured on the fourth axis. This allows the system’s control unit to detect whether the valve can easily be turned in the internal thread of the testing system. If the measured force increases, the jam can be released by briefly reversing the rotary movement.
This simple solution ensures that the valve does not jam, which prevents the system from coming to an unplanned standstill. The major advantage is that the force measurement is integrated into the drive system. This means that no external sensors are required.
From the perspective of everyone involved, the cooperation between Stäubli, Argo-Hytos, and Resim on this project was extremely productive and goal-oriented. The production line was put into operation in spring 2022, and after two years it is now working just as efficiently as when it was installed. Argo-Hytos has achieved its goal of fully automating the complex final assembly process of the electromagnetic hydraulic valves. The valves meet the highest quality standards and the Stäubli team is proud to have been part of this successful collaboration.
