| Starting point / Task definition |
 | | Durability testing of water fittings |  |
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| Implementation / Solution |
| It soon became clear that in order to simulate the very complex and in part circular motions of single-handle mixers, only six-axis jointed-arm robots were suitable. Only these robots could ensure the high precision demanded by the standards. The MPA NRW therefore invested in two KUKA KR 6 robots. In addition to high endurance and repeatability, the robots have to demonstrate great flexibility with regard to the water fixtures, which come in many different forms.
It is this flexibility which makes it possible to create any desired cycle, including the sequence and number of motions. The MPA NRW has programmed two test cycles for the fixtures. The robot always begins in the starting position: down and in the middle. From this position, mixed water off, it carries out the first cycle, moving in sequence through the settings mixed water on and off, cold water off and on, and hot water on. The robot remains in this position for five seconds, then moves the handle to cold water on. It waits there for another five seconds, then goes to cold water off, hot water off, hot water on and hot water off. It then returns to the starting position. The sequence in the second cycle varies; for example, the KR 6 may move diagonally from the starting position directly upwards and sideways to hot water on. In order to ensure reliable, traceable results, the measuring sensors are calibrated along the entire measuring chain. The signals of the force and torque variables are picked up by an instrument amplifier and transferred to the robot controller. |
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| System components / Scope of supply |
- Two KUKA KR 6 robots
- Two PC-based robot controllers, including control panel with Windows interface
- Robot programming
- Commissioning
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| Results / Success |
- Continuous performance
The KUKA robots are in operation continuously for the nearly five weeks of the test phase. The MPA NRW interrupts this only once per week for just under four hours. This time is used to carry out sealing tests upstream and downstream of the cartridge seat and to check the cross-flow. When the robot turns off the fixture for the last time at the end of a test, it has completed a total of about 70,000 cycles. If desired by the customer, the test can be extended for longer than the time required by the standard.
- Greater precision
Compared with a conceivable alternative solution employing rotating pneumatic cylinders, the KR 6s operate with much greater precision.
- High availability
Availability is nearly 100%, and is further enhanced by prompt after-sales service provided by KUKA Roboter.
- Flexibility
The robots’ flexibility means that they can also be used for other tasks.
- Easy programming
The basic program for both cycles is stored in the robot controller. Since, however, each water fixture has a different handle, and thus requires different motions, an MPA NRW employee has to teach these differences to the robot. This programming is very easy, however, and can be completed in a half a day, including installation of the fixture in the test cabinet. A major help here is the KUKA Control Panel’s familiar Windows-based user interface, which makes it easier for operating personnel to work with the controller. |
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