The TUBUS series of structural and safety dampers from ACE comprises a total of eight designs with over 150 individual products for a wide range of applications. It is possible to generate almost linear, progressive or, as with use in a computer tomograph (CT), degressive characteristic curves. The expensive heart of a CT system is the ring tunnel known as the gantry. This rotates many times through 360 degrees. This creates several contiguous layers during the scan, from which the computer can calculate a volume. This provides spatial information. Each individual pixel can be classified spatially. If required, the data obtained can be visualized by computer software not only in a 2D but also in a 3D image. For the purpose of quality control in the automotive sector, a project by LISCO GmbH from Bargteheide involved creating a feed table to the gantry using high-precision linear axes. Electrical limit switches monitor the permitted end position of the slide to prevent damage to the construction. To ensure that this is also impossible in the event of operating errors, hacker attacks or power failures, the LISCO GmbH team led by Managing Director Stefan de Bruyn decided to secure the end positions of the construction using solid-state dampers that operate independently of the power supply. After considering the characteristics such as table part length, weight and approach speed, the choice fell on TUBUS structural dampers of type TA-17 from ACE Stoßdämpfer GmbH. These axially damping machine elements made of co-polyester elastomer have a stroke of 7 mm and a maximum energy absorption of 6 Nm per stroke in continuous operation and 9 Nm per stroke in emergency operation. This makes them one of the smaller representatives of ACE's structural dampers and demonstrates that design engineers have a wide range of options for emergency stop and continuous operation in their systems and machines when selecting the right TUBUS for their application. In addition, the components in the case described also serve a second purpose when transporting the CT systems. If the carriage is not secured, they prevent damage caused by collisions. The structural dampers are quick and easy to attach using a special screw and provide LISCO GmbH with additional insurance in the event of an emergency stop, as they "function absolutely reliably", says Stefan de Bruyn.

LISCO GmbH secures the end positions of the linear axes on a feed table for an industrial CT system using integrated TUBUS structural dampers from ACE. © LISCO GmbH

TUBUS specials increase the productivity of pressing tools in automotive production worldwide
At first, it was a single car manufacturer that approached the Langenfeld-based company ACE. The customer from southern Germany reports: "We had already had extremely positive experiences with industrial shock absorbers from ACE in the fast, safe braking of sliders weighing up to 3 tons. It therefore made sense for us to turn to ACE for this new problem." The problem of increasing downtimes due to defective dampers in the dies during sheet metal forming was caused by the introduction of modern ProgDie presses and servo presses. Higher press stroke rates and speeds as well as the trend towards larger tools led to higher loads. The polyurethane (PU) damping elements were unable to cope with this. Material fatigue occurred too quickly. Tool breakages and production downtimes followed. In their search for new dampers, the car manufacturers at ACE came across TUBUS structural dampers. Made from co-polyester elastomer, they are up to twenty times superior to materials such as steel springs, PU or rubber stoppers in terms of damping properties and service life.

Compact design with high force absorption from 870 N to 90,000 N characterize all representatives of the TUBUS-TA family. They work with axial damping and have been specially developed for maximum energy absorption in the force range from 2 Nm to 2,951 Nm per stroke. © ACE Shock absorber GmbH

This was the reason why ACE succeeded in this case in replacing the predecessors of urgently needed hold-down dampers in sheet metal forming with the new TUBUS-Spezial development. At the same time, these special machine elements demonstrate what ACE's engineers can achieve on customer request. In addition to special deliveries with individual strokes, characteristic curves, spring rates and sizes, ACE offers special series for car manufacturers in the form of hold-down and lifting dampers. The success of these components is based on three years of development work, always closely geared to the needs of the respective customer. After first carrying out endurance tests in the laboratory to determine the maximum possible load and then testing in selected pressing tools and calculating the selection tables for the elements at well-known German car manufacturers, ACE determined the static and dynamic force-displacement characteristics as well as the energy absorption and absorption on test benches. Initial static and dynamic tests were promising, as under static conditions it was possible to achieve a maximum energy absorption of between 5 and 269 Nm for the hold-down dampers, which are only 29.4 mm high, depending on the design. Under the dynamic conditions prevailing in practice, the results of the previously used PU elements of the same height were exceeded almost threefold. As a result, TUBUS-Spezial have to be replaced less frequently than their predecessors and, thanks to the reduced downtime and maintenance times, significantly increase the productivity of the respective systems.

ACE offers damping elements made of co-polyester elastomer in many variants. Customer-specific, cost-effective solutions for press tools in sheet metal forming have been developed in the form of the TUBUS special hold-down damper shown here © ACE Shock absorber GmbH

One of ACE's services for car manufacturers was to create a selection matrix for each type of damper for the commissioning company during product development. Toolmakers can now use this to easily determine the size and number of dampers. The speed and weight of the hold-down device as well as the press stroke rate are taken into account. The values on which this is based are taken from test series carried out on a drop tester with a laser displacement measuring system. As a result of the tests at ACE, the team led by Product Manager Thorsten Kohnen created selection tables for press stroke rates of ≤ 17 up to 40 strokes/min and also connected several TUBUS special types in series. As a result, the practical tests in the tools used by vehicle manufacturers have resulted in more powerful hold-down and lifting dampers than previously available for holding screws in sizes M10 to M30. These ACE dampers are now supplied to manufacturers all over the world.

How high the energy absorption and durability of the TUBUS special hold-down dampers are was determined in a series of tests on test benches at ACE. © ACE Shock absorber GmbH

ACE now also offers aluminum and steel components for emergency stops
ACE has added crash dampers to its product portfolio to prevent damage when using linear units in robotics and to protect the end positions of machine tools, conveyor systems and high-bay storage and retrieval machines. These are made of specially designed aluminum or steel tubes that fold up in a predefined manner in the event of an impact, similar to a crumple zone, and convert the kinetic energy into heat. These new machine elements from ACE protect structures in the event of an accident by absorbing 98 percent of the energy evenly. Due to their mode of action, the crash results can be reconstructed and thus avoided in the future after appropriate evaluation. The crash dampers offer great long-term stability in everyday operation as well as excellent protection in the event of an emergency stop. They are also easy to fit and replace after a crash. The new crash dampers provide design engineers with a highly effective and economical one-way solution to effectively protect systems or machines. They therefore represent an interesting alternative to irreversible and reversible structural dampers and hydraulic safety shock absorbers. The new safety products are available with external diameters of 87.5 mm in the aluminum versions and 63 mm and 38 mm in the steel versions. Ten basic types are available as standard, with energy absorption in emergency stop applications ranging from 670 Nm/stroke to 11,200 Nm/stroke. Depending on the type, the maximum stroke of the components is between 45 mm and 160 mm, whereby the low support forces of 13,000 N to 70,000 N make a decisive contribution to securing structures. In practice, these values can be further increased by arranging the crash dampers in series or in parallel in order to dissipate higher energy values in one go. The new crash dampers are available from stock in Langenfeld within 24 hours and, like the structural dampers in the other application examples, are characterized by a good price-performance ratio.

Further information:
Structural damper
Safety damper