Dampers functional tester (CTS)
A machine for testing the characteristics of forces during compression and rebound of dampers. Fully automatic and modular. It can be a separate stand or an element of the assembly line of dampers or gas springs.
Main test parameters
|Test force||Max +/- 10kN (typical +/- 6,5 kN)|
|Test freq||16 Hz|
|Test speed||up to 1500 mm/s|
|Damper stroke measurement||up to 400 mm|
|Acceleration||up to 10g|
|Acceleration curve||Sine, trangle, trapezoid|
Electromagnetic and hydraulic drive comparison
|Actuator||Linear EM drive||Hydraulic|
|Measurement error||1,5 %||up to 10 %|
|Cycle time||6,8 s||7,2 s|
|Stroke measurement||<= 400 mm||< 350 mm|
|Force range measurement||max +/- 10 kN
(typical: +/- 6,5 kN
|+/- 5 kN|
|High frequency test||YES||NO|
Automation of the testing process
When trying to automate the process of testing the damping force characteristics of dampers, it is necessary to use appropriate drives, forcing movement to measure the relationship between the vibration amplitude and their frequency, taking into account different damping coefficients. As practice shows, most testers are not able to simulate movements that reflect the dampers work in real conditions. In addition, the characteristic test requires the smallest possible measurement error, which can be as much as 10% in standard applications. Short cycle times and precise stroke measurement over a large range are a must. For the proper performance of the damper characteristic test, it is necessary to measure the force with the specified precision. In view of the above technical assumptions, expected by dampers manufacturers all over the world, we designed and built a system that allows to determine the damping force characteristics of a damper with the accuracy achieved so far only on laboratory machines.
Typical solutions are based on a hydraulic effector that moves the damper piston rod with the appropriate force or on a constant test amplitude achieved by transmitting power through the crank mechanism. The design of hydraulic drives has its drawbacks, the main of which is the dependence of speed on oil temperature and acting loads. Oil, as the main working medium, is also very sensitive to contamination that is harmful to the drive. In fact, the only preventive measure is sufficiently frequent oil changes, which entails time and resource-consuming servicing. Multiple transformations of energy in the hydraulic drive result in its lower efficiency compared to electric solutions. Crank solutions, on the other hand, do not provide the expected flexibility in production, as the production of a different product can only be introduced by means of a mechanical replacement of the crank. For this reason, they are used mainly in measuring laboratories, where the cycle time is not so important.
In the CTS, of an innovative ELPLC design, it was decided to use SIEMENS electromagnetic linear motors as a test effector drive. In this way, a compression force (Fmax) of 10kN was achieved. The choice of the engine was also determined by its maximum speed (Vmax) reaching 90 m / min. This parameter allowed to shorten the test cycle time. The cycle time was 6.8 s - in the case of hydraulic drives it is 7.2 s. The force measurement is supplemented by a control of the stroke length per unit time. The measurement error of the entire measurement system was reduced to the level of 1.5%. It should be emphasized that on a hydraulic drive-based machines, this parameter is even 10%.
Replacing the classic hydraulic drive brought many benefits: no additional oil supply system, no need to control the temperature, pressure and oil consumption, high control dynamics at high power, enabling testing of a new type of valves that operate on the principle of mechanical switching depending on the frequency of piston rod movement. In this case, the change of the drive technology has brought not only energy efficiency, but also specific operational and quality benefits in the form of a shorter cycle and more accurate measurement.
It is worth emphasizing that the tester can also be one of the elements of a complete, modular technological line for the assembly and testing of dampers. The solution is, in turn, ELPLC's answer to the needs of manufacturers who expect automation of the dampers assembly process, taking into account autonomous operation, high accuracy of assembly and tests, as well as durability and energy efficiency. The line requires personnel only for loading and unloading operations, which can ultimately be carried out also by robots and AMR / AGV.
- Machine for testing the compression and rebound characteristics of dampers
- Fully automated, modular, it can be an independent station and an element of the assembly line of dampers or gas springs
- Successfull installations in Poland, USA, Mexico and the Czech Republic