Two German companies have been cooperating successfully in the field of measurement technology for many years in order to be able to precisely test industrial damping technology in the area of dynamic parameters for customer-specific projects. Here they provide insights into their collaboration.

In many automated production processes, small and industrial shock absorbers are used as efficient, currentless hydraulic components for deceleration or the precise braking of mass forces in order to increase productivity and safety. ACE Stoßdämpfer GmbH provides a wide range of these machine elements in the form of self-adjusting and adjustable types for a wide variety of applications, enabling designers to cover the most common force ranges with the company's standard components.

Sensors and simulations play a role when engineers want to precisely determine the actual damping characteristics of the respective ACE shock absorber types for their specific application in advance for particularly sensitive applications. This applies in special cases in the fields of automation and handling as well as for the deceleration of extraordinarily high mass forces on machine tools or rotary tables. If the damping curves specified by the manufacturer are not sufficient for the application and for the customer's project team, ACE's consulting engineers use in-house testing facilities to check the theoretical simulations from the designs with standard components in practice and validate them.

Damping technology tested on drop testers and test bench

Two drop testers are used in Langenfeld, the German headquarters of ACE Stoßdämpfer GmbH, a member of the Stabilus Group. The first covers mass forces from 130 kg to 500 kg with a maximum drop height of 1500 mm. The drop tests carried out according to the laws of gravity result in maximum impact velocities of 4.8 m/s (v = √2*g*h) and kinetic energies of approx. 6000 Nm (m*g*h). The second drop tester is suitable for masses from 3 kg to 350 kg with a maximum drop height of up to 1500 mm, whereby impact velocities of up to approx. 5.5 m/s and energies of up to approx. 5150 Nm are measured. In addition to these gravity-induced test options for shock absorbers at the end of the travel of vertical linear axes, a special test stand also enables horizontal linear tests. The drive accelerates masses from 20 kg to 100 kg to speeds of up to approx. 3.5 m/s.

In a practical example in which high-precision, friction-free axes are installed in a handling system that is secured in the end positions in three axes (X, Y, center pole) by small shock absorbers, the engineers at ACE first select the appropriate damper types for the respective axis from the standard range. Because the highly sensitive axles may only be loaded with defined maximum forces in the event of a crash, ACE carries out specific theoretical designs for each of the selected small shock absorbers using simulation software in the second step. Each individual hole pattern, i.e. the number and size of the throttle holes inside the damper, is simulated on the computer in order to optimize the force progression, i.e. the force-displacement curve. The engineers can then validate the theoretical simulations by taking measurements on the linear axis using appropriately prepared test specimens in the linear tests on the test bench. In such a test application, the moving mass can be adjusted down to a few grams and the impact speed can be matched almost one-to-one with a tolerance of 0.02 m/s for each specific case. If the test specimens pass the tests, the measurement results are used for the production of the required small series.

Measurement technology validates simulation and test results

Whether ACE components are tested in vertical or horizontal linear axes, the company uses a laser displacement measuring system to determine the damping travel and force sensors to determine the actual support force for all test benches. The company has been cooperating with Burat & Klein Datentechnik GmbH, based in Meckenbeuren in the Lake Constance district, since 2004. While the various sensors and displacement transducers are connected to a measuring system called MultiMessBOX, which is precisely adapted to the respective test point, the data determined in each test run can be evaluated using the MessMax® software programmed by Burat & Klein. As described in the sample case, MessMax® makes it possible to superimpose the curve measured during the real test with the theoretical curve determined on the computer and thus validate the theory in practice. Jörg Küchmann, engineer from ACE's research and development department, comments: "In the application cited, Burat & Klein was able to offer us special evaluation software with which we can compare three parameters and automatically export the results to Excel as required. In this case, the maximum support force, the maximum damping distance and also the energy, i.e. the area under the force-displacement curve, are evaluated and checked."

Over the past few years, ACE has gained extensive experience in this area of measurement technology and the evaluation of the results obtained thanks to the increasing number of validations requested by customers. It is remarkable that the simulations show only very small percentage deviations compared to the actual measurement results in practice. ACE's simulations are therefore also very accurate thanks to Burat & Klein's measurement technology.