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仪器交易网 > 仪器知识 > 技术参数 > 撼神高频率液压缸应用在疲劳试验机 疲劳试验机技术指标

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撼神高频率液压缸应用在疲劳试验机 疲劳试验机技术指标

时间：2020-07-30    来源：仪多多仪器网    作者：仪多多商城     
Hydraulic cylinder vibrates to a 400 Hz sine.

(DYNA-MESS Gmbh) and Hänchen reach new heights of performance

Modern quality standards mean that components are now facing more varied and useful tests than at any time before. DYNA-MESS Testing Systems specialises in testing machines for dynamic component and material testing. With its broad and varied range of standard and special test machines, the Aachen-based company exploits the possibilities of modern fluid technology to the best advantage. Its pièce de resistance is a special testing machine for elastomers which, with the help of standard hydraulic cylinders from Hänchen, realises controlled vibrations of 400 Hz in order, for instance, to test the damping of bearing elements made of rubber-metal composites for the automotive industry.

Hydraulics is cutting-edge technology

According to Dr. Marcus Jarchow, Managing Director of DYNA-MESS, "these test units are exposed to extreme stresses with a nominal force of 10 kN and a frequency of anything from 0 to 400 Hz. It has been extremely difficult to find a suitably high-performance hydraulic cylinder on the hydraulics market", because the test device depends on the perfect stick-slip behaviour of the hydraulic system. Cylinders with hydrostatically supported piston rod guides are normally used for this type of application, but the technical expenditure for this solution is enormous. "We have nevertheless kept our ears to the ground to try and find out who can offer some help with finding a solution" stated the Managing Director of DYNA-MESS. "Everybody hesitated when we mentioned the technical requirements, with the exception of Hänchen Hydraulik. A further argument in their favour was that they had their own test equipment and would be able to base their results on extensive experience. Ultimately, the hydraulic specialists from Ostfildern, near Stuttgart, offered a standard cylinder with patented, floating annular gap seal which is considerably more cost-effective than drives with hydrostatically supported piston rod guides". The PZL assembly series from Hänchen, however, also provides these high-end cylinders.

The PZR floating annular gap seal

The patented, floating annular gap seal from Hänchen permits the use of cost-effective PZR high-end test cylinders, in which a steel sleeve is positioned through a choke gap and thereby creates a contact-free sealing gap of just a few 1/100 mm. This process can, however, only function correctly with a production accuracy of only a few µm, as leaks would otherwise lead to an unacceptable loss of hydraulic fluid. This PZR assembly differs only by the slightly lesser absorption of the lateral forces from a cylinder with hydrostatically supported piston rod guide, but yields a considerable cost advantage. Thanks to their negligible friction, however, PZR cylinders offer maximum positioning and repeat accuracy and are stick-slip free, making them ideally suitable for extremely slow as well as fast movements and minimum travel over ranges of a very few µm. As lateral forces are not experienced in this 400 Hz DYNA-MESS test equipment, the decision was made in favour of these cylinders.

High-quality peripherals

The cylinder is equipped with a special inductive position measuring system and a force transducer with an extremely low natural frequency and yield measuring strips. Both sensors supply analog output signals which are digitalised with a resolution of 16 Bit and tested with more than 20 kHz. They supply the control with the necessary data, which must be converted practically in real time by a control card with its own high-performance processor. Tried-and-tested DYNA-MESS software modules were adapted to the special conditions to facilitate programming. A PC forms the basis for the Windows user interface. The valves represented yet another technical challenge, as they have to work with a control frequency of 16 kHz. The fluid circuit has been designed for 300 bar and operates at 40 l/min. This high power density enabled a low design size, because a high frequency with a wide frequency spectrum places extremely high demands on the mechanical construction: the frame must not have any natural resonance over the whole of the frequency range.

Commissioning

Commissioning proved to be a time-consuming exercise, particularly due to the need to tune in to the various frequency ranges. The frequency was increased in steps of 10, 20, 30 … up to 400 Hz, with the resonance having to be minimised at every stage. The complete control was also tuned during this time, in that the runtime delays between the reaction of the processor and its execution by the hydraulic system are captured and included in the control. Finally the control quality and curve form were optimised, this operation being followed by fine tuning with the help of a friction-free and loss-free spring, which measures the dynamic without phase displacement and so enables material tests to be carried out under clearly defined conditions. After up to 400 Hz had been reached, Dr. Jarchow’s team carried out further tests up to a frequency of 1,000 Hz. "We were surprised at what outputs were possible, up to double the nominal output at 800 Hz", said the hydraulic specialist. "It was only above this frequency that the limits of what is technically feasible at the moment were clearly reached. The hydraulic cylinder has more than matched the requirements placed on it, and that was with the use of a catalogue cylinder and at a very attractive price”. The finished system was then commissioned during the first quarter of 2002.

Practical application

Hänchen’s PZR hydraulic cylinders are now being used by a Daimler-Chrysler supplier to test vibration dampers for engine and gearbox suspensions for load carrying ability, damping behaviour and service life. These components are made from rubber-metal composite material with embedded passive hydraulic damping. The sealed glycol circuit in this component is used to dampen the vibrations. A new test bench enables the developers to optimise the damping characteristics. Sweep tests with a pre-selected load which corresponds to the engine or gearbox weight are used to determine at which frequency damping is most effective. For this test the frequency is superimposed over the static load with the aim of achieving an optimised damping over the whole frequency range of up to 400 Hz."

Our engineering competence, the experience and evaluation of our suppliers as well as the ability to develop test solutions together with our customers were the deciding factors", explained Dr. Jarchow, whose team performs all calculations, is responsible for design, software, electronic development, control, configuration as well as installation and realises the complete system in co-operation with the suppliers. "Suppliers whose products conform to our own high standards play a critical role. That is why we are working together with Hänchen Hydraulik".



    今天我们来讲一下怎么维护保养橡胶缓冲块疲劳试验机。

    1、定期更换油路滤芯，对变质油及时清理。设备运行过程中，难免会出现一些故障，故障让金属造成污染，污染到滤芯，所以定期更换系统的油路滤芯，把被污染的油或者是已经不干净的油清理掉，及时更换新的油。不仅可以提高工作效率，而且也可以减少设备出现故障。

    2、更换液压油，并且加强管理。液压油长期工作，一定会有氧化焦化的现象出现，而且在液压系统中会零件容易磨损，一旦磨损就会有金属屑掺杂在液压油中，大大降低油品，造成严重故障。有专家表示，液压油的更换周期一般在十个月，这样可以保障设备正常运转。

    3、更换伺服阀。设备出现故障，也有可能是伺服阀的动作不良所造成，所以定期清洗和更换伺服阀是很关键的，既能够防止污染，也可以杜绝出现故障。

    4、更换密封圈。密封圈主要是为了防止出现漏油的现象，如果密封圈不在密封，应该及时更换，保持有效工作。

    5、更换滤芯，想要保持液压系统的干净卫生，滤芯一定要及时更换，工作人员结合实际情况来调整更换周期即可，毕竟每台设备的工作量不太一样。






疲劳试验机的维护方法
　　疲劳试验机用于进行测定金属、合金材料及其构件在室温状态下的拉伸、压缩或拉压交变负荷的疲劳特性、疲劳寿命、预制裂纹及裂纹扩展试验。疲劳试验机需要进行定期的维护可以保障仪器的正常运行，那么用户应该如何维护疲劳试验机呢?下面小编就来具体介绍一下疲劳试验机的维护方法。

　　1、定期更换油路滤芯，清理变质油

　　电液伺服压力试验机由于此次故障由液压油中金属污染造成，因此定期更换该系统油路中的滤芯，放掉滤油器中存油，可防止污物进入伺服阀，有效的防止故障发生，延长伺服阀的运行时间。

　　力矩马达和先导阀完全浸泡在与回油相通的油液里，位置又处于管道的盲端，所以该处的油液几乎不流动，易氧化变质，因此需定期放掉变质的液压油。

　　2、定期更换液压油，加强液压油的管理

　　液压油在长期工作中会氧化焦化，并且液压系统中的泵.阀、油缸等的磨损，会产生一些金属屑，它们会降低液压油的品质，造成故障。根据近几年液压油使用周期和油品化验结果，要每10个月更换一次液压油，才能保证设备无计划外停机。

　　3、定期更换伺服阀

　　有些故障的直接原因为力矩马达被污染导致伺服阀动作不良，因此定期清洗、更换力矩马达和先导阀，防止污染，从而杜绝故障发生。伺服阀的装拆应在尽可能干净的环境中进行，操作时应先去掉接到伺服阀上的电气信号，再卸掉液压系统的压力，然后拆下伺服阀。在干净、相容的商用溶剂中清洗所有的零件，零件可以晾干或用软气管以洁净、干燥的空气吹干。清洗后的伺服阀，可以作为备件轮流使用，降低费用。

　　4、定期更换密封圈

　　定期检查主机和油源处是否有漏油的地方，如发现有漏油，应及时更换密封圈或组合垫

　　5、定期更换滤芯

　　液压滤芯概述液压滤芯应用在液压系统中，用于滤除系统中的颗粒杂物及橡胶杂质，保证液压系统的清洁度，根据机器的使用情况及油的使用期限，定期更换吸油过滤器和滤芯。余姚表；立式恒温恒湿试验箱：日本优易控仪表；洁度，根据机器的使用情况及油的使用期限，定期更换吸油过滤器和滤芯。

标签: 疲劳试验机
疲劳试验机 疲劳试验机的维护方法_疲劳试验机

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