Distances and displacement in a variety of R&D and industrial applications can be precisely detected by draw-wire sensors. They are easy to install, reliable, and are perfectly suited to serial applications as a result of their relatively low cost.
Micro-Epsilon offers a wide variety of draw-wire sensors and is now revealing another achievement - the earth’s smallest draw-wire sensor, which is specifically designed to perform high-speed measurements.
With straightforward installation, draw-wire sensors are maintenance-free and operate reliably. In addition, there is no difficult alignment work required. Even extremely tight installation space presents no challenge to these versatile distance and displacement sensors.
They measure distance and displacement in high acceleration applications and OEM tasks, dependent upon the model. These positive traits allow them to be used in versatile industrial applications, medical engineering, mobile machinery, and test rigs.
There are a number of application possibilities, from measuring lift height for bridge maintenance to training monitoring in rehab devices, measurement tasks in machine tools and the positioning of catering vehicles and operating tables.
Among the numerous models available, the new miniature wireSENSOR MT19 from Micro-Epsilon is a stand-out. It’s as small as a 1 cent coin, and is, therefore, the smallest draw-wire sensor in the world.
Small Sensors Achieve Big Things
Micro-Epsilon’s new wireSENSOR MT19 miniature sensor stand-outs from the various models on the market. It is the world’s smallest draw-wire sensor, measuring just the size of a 1 cent coin. This model is specifically designed for test applications with high wire accelerations over measurement ranges of as much as 40 mm.
For instance, the MT19 is used in test applications for racing cars and aircraft. In addition, the miniature draw-wire sensor is especially well equipped for performing crash tests. Vital information concerning the tested vehicle’s safety is provided by the deformation values of the crash test dummies. By exactly determining this deformation, engineers can optimize the design of passenger or interior compartments, enabling them to optimize passenger safety.
The new wireSENSOR MT19 from Micro-Epsilon is particularly well suited to crash tests. The deformation values of the crash test dummies give vital clues about the safety of the tested vehicle.
There are various sensors built into a crash test dummy. The spinal column, chest, pelvis, head, and legs are given particular attention. Draw-wire sensors are installed directly in these parts of the dummy, to ensure deformation values which are as realistic as they can be.
Yet, there is a limited amount of installation space here. This is not a problem for the MT19 miniature draw-sensors from Micro-Epsilon as, courtesy of their through bore housing and compact design, they can be installed in extraordinarily tight spaces very easily.
A robust aluminum housing is used to protect the MT draw-wire sensors. As the draw-wire sensor is designed specifically for very high acceleration tasks, it can follow these high-speed movements.
These stresses can be withstood by the wireSENSOR MT19, as it is designed for accelerations reaching 60g. Derived from an idea which was well-conceived, it delivers precise distance and displacement values in order to fulfill the extremely high requirements expected of sensors during crash tests.
Two more miniature MT sensors have been launched by Micro-Epsilon for high-speed measurements in confined spaces. Although the wireSENSOR MT33 can measure distance and displacement at measuring ranges as high as 80 mm, the MT56 can perform measurements as high as 130 mm. Each of these is equipped with a stainless steel measuring wire, a potentiometer, and an aluminum housing.
Robust Draw-Wire Sensors for Industrial Applications
Micro-Epsilon is an expert in the industry of industrial measurement technologies. During its 50 year history, it has developed a wide-ranging, high-quality variety of draw-wire displacement sensors. Numerous models cover measuring ranges between 40 mm and 50 m.
Micro-Epsilon offers wireSENSOR P draw-wire sensors, in addition to sensors designed for high-speed measurements, which are designed specifically for industrial applications. These sensors have applications in crane systems, elevator construction, high-bay warehouses, and forklift trucks.
These sensors are protected from mechanical influences courtesy of their compact and robust aluminum housing. Furthermore, it is possible to purchase Micro-Epsilon draw-wire sensors as analog versions with a potentiometer, voltage or current output, or as digital versions with absolute or incremental encoders.
Load Tests on Rotor Blades
When performing stress tests on wind turbine rotor blades, wireSENSOR P draw-wire sensors are used. Consequently, test rigs which imitate the real loads caused by storms and winds have been developed. Made from fiber-reinforced plastics, these expensive rotors are manufactured in line with the half-shell sandwich construction. Generally, they measure from 40 m to 60 m long.
A test rig which can test rotor blades as long as 70 m has been developed by the Fraunhofer Institute IWES in Bremerhaven. The rotor blade is mounted horizontally in the test rig. With the use of guide pulleys, steel cables are routed to the rotor before being attached to the rotor blade at differing positions either via mechanical clamps or directly.
As a result of mechanical loads, the tip of the rotor blade is liable to be distorted by as much as 10 m. To measure the distortion, twelve draw-wire sensors are used. The torsion and deflection of the rotor blade are measured by two sensors per traction point.
In order to do so, rails on the ground are used to mount the sensors before the measuring wire is connected to pre-fabricated eyes on the terminals. Here, the sensors impress with their ease of use and robust design while covering measuring ranges between 3 m and 10 m. The digital signal produced is used in future simulations.
wireSENSOR P draw-wire sensors are used when performing stress tests on wind turbine rotor blades. Two sensors per traction point measure the deflection and torsion of the rotor blade.
Lift Height Measurement for Two-Column Lifts
In two-column lifts, draw-wire P sensors also ensure that the vehicles are lifted evenly. Typically, in modern two-post lifting systems, no base frame is included within the design. These modern systems do not any longer need a mechanical connection, unlike lifts in which there is a chain between the two lifting columns. As a result, there is no need for the threshold between the lift columns.
Consequently, as no “obstacle” must be overcome during entry and exit, this makes the user’s daily work much simpler and so it is significantly more straightforward to position the vehicle. Although, there is no longer any “automatic” lift height synchronization, which used to be provided by the two columns’ mechanical connection.
The lift consequently needs a lift height monitoring system or a synchronization controller in order to guarantee the vehicle is raised evenly on each side. For this kind of height measurement, draw-wire sensors are preferred, because they are simple to integrate, extremely compact, and offer an extraordinarily attractive ratio of price/performance in relation to the measuring range, in addition to high accuracy.
Versatile Draw-Wire Sensors for OEM and Serial Applications
Micro-Epsilon’s draw-wire MK sensors are perfect for applications in which high quantities are needed, as they are designed specifically for serial applications. Their low cost and compact design constitute significant advantages, as well as the easy integration they offer ( even in tight spaces). High performance and an affordable price combine in the MK sensors from Micro-Epsilon, as well as robust and compact design. These characteristics are perfect for serial applications.
8 Times Longer Service Life with WPS-MK88
The new wireSENSOR WPS-MK88 U45R equipped with a non-contact potentiometer can deliver 8 times more working cycles than draw-wire sensors based on a conventional potentiometer. This prolongs the service life of the sensor as much as possible.
When taken with a positive price/performance ratio and a robust plastic housing and a favorable price/performance ratio, this technology establishes new levels of economic efficiency. Via the replacement of the conventional, analog hybrid potentiometer with a non-contact potentiometer, those favorable assets were achieved.
Traditionally, a sliding contact (wiper) travels across a resistive element in a common potentiometer. Yet, this quickly causes the wiper to wear. Conversely, the service life of the new, non-contact potentiometer is drastically improved, as it is based on magnetic field sensors.
Safety in Forklift Trucks
In sectors in which high cycle rates are needed, such as for forklift trucks or in logistics, MK sensors can be used. Safety margins which might normally be considered large must be observed during the lowering of the load, in order to ensure that the truck does not get into a dangerous, tilted position when rounding a corner, braking, or accelerating.
As draw-wire sensors can now be used to measure the load’s lift height, it is possible to ascertain the optimum driving speed. Furthermore, there is little risk of operation, as the operator is not able to cause critical driving conditions, whether wittingly or unwittingly.
MK sensors from Micro-Epsilon are used in sectors where high cycle rates are required, e.g. in logistics and for forklift trucks.
Determining the Position of the Tailstock in Machine Tools
Ascertaining the tailstock’s position in machine tools constitutes another frequently encountered measurement task. In these instances, Micro-Epsilon’s draw-wire MK sensors are used.
Even though there is no direct impact from this measurement on the machine's safety or precision, it presents numerous difficulties to designers. Therefore, frequently, the center point of the tailstock’s position must be determined over an extremely large area of as much as a few meters. What makes the situation worse is that there is limited space for the corresponding measuring system.
However, Micro-Epsilon sensors can be easily mounted into confined spaces, consequent upon their compact design. As the measuring rope can be guided in an extremely flexible manner in places which are difficult to access over a range of pulleys, there is no need for the sensor to be installed directly in the tailstock’s vicinity.
Measuring ranges of between 300 mm and 2100 mm are offered by typical draw-wire sensor models for machine tools, however, there are also larger ranges available. Long-term stable application in machine tools is ensured by their robust plastic housing, which protects the sensors from thermal and mechanical stress and loads.
Thus, the position of the center point of the tailstock often has to be determined over a very large area up to a few meters. To make matters worse, the space for the corresponding measuring system is often limited. However, Micro-Epsilon sensors can be easily mounted even in confined spaces due to their compact design.
Box: How Does a Draw-Wire Sensor Work?
A drum, measuring wire, spring and an encoder or potentiometer combine to make a draw-wire sensor. In order to prevent the wire from sagging, the spring tensions the measuring wire during retraction and extension. This makes sure of the correct detection of the displacement the wire has traveled, in order to provide exact measurement values.
The stainless steel measuring wire, which is extremely flexible, is wound onto a drum, onto which the encoder or potentiometer is mounted. This drum rotates when the wire is unwound or wound up. Consequently, the moment the measuring object (on which the measuring wire is mounted) moves, the encoder or potentiometer rotates proportionally to the drum.
It is then possible to convert the drum and encoder/potentiometer’s rotation, caused by the distance change, into a proportional, electrical signal. The encoder is used for digital output signals, whilst the potentiometer is used for analog output signals. It is possible to transmit the determined signals through different outputs so that they can be evaluated.
This information has been sourced, reviewed and adapted from materials provided by Micro-Epsilon.
For more information on this source, please visit Micro-Epsilon.