Häko Product configurator HÄKO Logo print
High-performance hydraulic test cylinder as test actuator
  • High quality and reliability of the test actuators
  • Stick-slip-free cylinder movements
  • Flexible and committed cooperation
  • High positioning and repeat accuracy
Photo of seat test stand with dummyPhoto test actuator with bladder and diaphragm accumulatorPhoto of an FSC digital controller
Image 1: Seat test stand with dummy in use
Image 2: Test actuator with bladder and diaphragm accumulator in the test stand
Image 3: The test stand control is managed by the Smartest digital controller, which can be used in stand-alone mode for programs, test cycles, and protocols.

Dynamic test machine

Technical test stand requirements

Electronics

  • 20 GB hard drive
  • Each unit can address up to 4 channels simultaneously
  • Larger FCS systems control over 300 channels
  • Ergonomic single-button control
  • Display in VGA format
  • PC keyboard

Benefit from our comprehensive know-how in hydraulic drives and modern test stand technology.
From decades of experience in the engineering of test actuators, we have developed into a general contractor for the construction of complete test stands and test machines. This also includes functional test stands for performing vibration tests and shock tests on end products.

Vibration test stand version for wear testing
Components to be tested in the test stand

The wear testing of the seats is carried out by a Hänchen test actuator series 320">test actuator from the former series 328 (today series 320) as an actuator. The patented, floating floating gap seal Servofloat® is used in this double-rod cylinder. A steel bushing follows the radial deflection of the piston rod, with a sealing gap of a few 1/100 mm that is practically constant over the entire pressure range. This cylinder series differs from a test actuator with hydrostatically mounted piston rod guide only in its somewhat higher sensitivity to side loads, but offers a cost advantage of around 30%. This is because only the leak oil seals cause a negligible minimum amount of friction. Due to their extremely low friction, test actuators in Servofloat® offer the highest positioning and repeat accuracy, are stick-slip-free and are suitable for extremely slow and fast movements.

The seat test stand operates in standard mode with a test force of up to 28 kN at a frequency of maximum 20 Hz, a dynamic stroke of up to 35 mm, a speed of up to 1.3 m/s and an acceleration of up to 50 m/s². Nevertheless, it still has high safety reserves that ensure optimum operation: The technically permissible maximum speed, for example, is 4 m/s.

Low-friction hydraulic cylinderPlay video: Please activate the YouTube cookie.

Video about the Servofloat® design

The servo hydraulic seat test stand tests not only complete seat structures but also adjustment devices, backrests, lordosis supports, springs, rails and trim parts. In addition, the test machine can be used to test foam parts for cracks and fractures and to determine the amount of settling in long-term tests, which is derived from the hysteresis shift.
Do you need a test stand for testing car or aircraft seats or similar? We can realize the implementation of your requirements!
Call now Write to us
Our special machine construction Ratio-Drive® offers you the complete implementation of test stands of all kinds.
Hänchen test stand construction

Structure of seat test stand
Use of test actuators

When the seat test stand system starts, a hydrodynamic oil flow is built up in the floating gap seal via the cylinder chambers. This allows the floating gap seal to move metallically without contact, 'floating' and self-centering radially around the piston rod. The exiting leak oil is returned to the fluid circuit without pressure via a collecting port. The absence of a touching, pressurised seal minimises static and sliding friction in the test actuator. Because no hydrodynamic lubricating film is necessary due to the relative movement of the sliding partners, stick-slip-free movement can also occur in the range of the smallest amplitudes and speeds. The floating gap seal only has a pressure-reducing function with minimal leakage. Therefore, the piston rod is guided by means of friction-optimised bands. Nevertheless, a test actuator with a floating gap seal can also absorb certain lateral forces. In the specific application, 1.2 kN are permissible, which are absorbed by synthetic guide strips. The test actuator series 328 (now series 320) also has anti-seizure properties due to the piston and bearing surfaces coated with special bronze, which additionally increase operational reliability.

The oil supply to the test stand is of decisive importance for the effectiveness of the floating gap seal. The cleaner the oil, the more reliably the system works. If the particles in the oil are no larger than 3/4 of the smallest gap height, the gap rings will not wear. Hänchen therefore recommends cleanliness class 13/11 according to ISO 4406. In test and testing systems, hydraulic cylinders with the floating gap seal offer a real high-performance cylinder with a significant price advantage compared to cylinders with hydrostatically mounted piston rod guide. Hänchen also offers these high-end test actuators, which can compensate for a maximum of lateral forces. As there is no starting friction, the low stick-slip operation is guaranteed even at the smallest piston speeds. Only the pressureless wiping elemento di guarnizione causes a low residual friction, which is constant over the entire pressure range. This avoids the complex and workplace-polluting extraction of leak oil.

"FCS and Hänchen work together very flexibly and with great commitment."
Dipl.-Ing. Andreas Hesse, FCS

Fulfilling the dynamic requirements of the test stand

The mounting plate for the servo valve mounted directly on the test actuator creates a compact servo hydraulic actuator system for the highest dynamic requirements of test stand construction. The catalogue cylinder selected by FCS and used by IAV has a mounting plate for each control valve and one diaphragm and bladder accumulator each to compensate for the pulsation of the pump and other disturbances in the fluid flow. The hydraulic cylinders also include specially selected low-play spherical plain bearing as standard and an emergency cushioning, in this application with 10 mm. Two inductive position transducers integrated in the test cylinder as well as mounted acceleration sensors and load cells supply the control system with the necessary data.
 
The Z axis moved by the hydraulic cylinder is decisive, which the FCS digital controller "SmarTEST One" controls via a control circuit that is addressed via displacement and acceleration. In contrast, a crank drive moves the Y axis. It triggers a superimposed translational sine movement. "SmarTEST One" is a universal digital controller that can be used in stand-alone mode without a PC and with its own 20 GB hard drive for programs, test cycles and logs. Each unit can address up to four channels simultaneously and in a coordinated manner. The larger FCS systems control over 300 channels. Most functions can be set via an ergonomic single-button control and a display in VGA format; a PC keyboard can be easily connected. The controller can automatically recognise and calibrate measuring transducers. The core of the smallest system from FCS is the SmarTest Control Unit, which has already proven itself over 1000 times in products from the Dutch control specialist. This processor system is characterised, among other things, by a range of safety functions such as constant self-tests, fail-safe design and independent tests of all inputs according to user-defined specifications. In addition to common functions, "SmarTEST One" enables the waveform to be edited. Signal processing and conditioning is carried out by the "FasTEST Manager" software from FCS. It generates load-time curves of the test stand and adapts them using a powerful iteration process. Depending on requirements, both analogue and digital data are processed. In this way, despite the 20 Hz of the actuator, highly dynamic loads beyond derived sine functions can be simulated, such as those that occur on a gravel road. This places just as high demands on the process clocking of the controller as it does on the hydraulic cylinder.
 
In this way, the IAV test system can run a large proportion of the test cycles prescribed by the automotive industry. The second axis ensures that the dummy realistically slides back and forth on the seat so that the test stand also simulates the fabric wear caused by horizontal movements. Up to three backrest or seat frames with seat or backrest dummies can be accommodated on the test rig and can thus be tested simultaneously. IAV brings the actual test know-how into the system: the programming of realistic test sequences, the interaction of the components and the advice to the user. The specialists provide advice on troubleshooting, particularly when weaknesses such as cracks, fractures, wear or settling occur during the fatigue strength test. With the test stand, the company offers a test facility that is both high-performance and economical for testing the quality of components under the most realistic conditions possible. According to team leader Dipl.-Ing. Andreas Hesse, what is decisive for the cooperation is "that FCS and Hänchen work together very flexibly and with commitment and that both companies also realise smaller projects with good quality."
Jörg Beyer, mediaword
© Hänchen 2006
 
 

Hänchen Ratio-Drive® - The complete solution for drive systems & test stand construction

  • More than half a century of hydraulic and seal competence
  • Extensive experience in special machine construction of hydraulic and electrical special machines
  • Experience in the systematised individual design and realisation of customer projects
  • Experience in the systematised individual construction of industrial machines and retrofits
  • Measurement, control and regulation technology, real-time control, measured value acquisition, sensor technology, fieldbus connection and evaluation
  • Development of proprietary modular software, including graphical interface for control and regulation as well as communication at process level
  • Individual test stand construction
  • Planning and implementation of test machines
  • Comprehensive safety concepts up to PLe in accordance with the Machinery Directive, CE conformity, safety software
APPLICATION REPORT
Vibration tests for transport simulation / Packaging industry
USER REPORT
Test machine for final inspection of hydraulic products / mechanical engineering
USER REPORT
Dynamic thread tensioner - dancer control / textile machine
APPLICATION REPORT
Large bearing test stand / Wind power
USER REPORT Multi-spindle automatic lathes / Drive
APPLICATION REPORT
Wing test stand / Aircraft industry
Menu
DE