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Positioning, centering, tilt, alignment

Different parts must often be positioned or products put in a specified place in production systems or for automatic movements. Thereby, sensors can only transmit the distance information to the controller or perform the complete system regulation with its signals. Welding robots with automatic weld seam guidance are an example of automatic regulation. Different sensors are used depending on which material the part to be positioned is made of.

3D measurement of components prior to plasma cutting

In order to process these huge domes quickly, fully automatically and at extreme precision, it is necessary to determine their shape and exact position within the production line. As the pure CAD data of the dome often differs by several centimeters from the actual dimensions, the 3D profile of the covers is measured before processing using scanCONTROL 2900 laser scanners. The exact dimensions are then determined from the 2D data generated by the scanner which is connected to a 6D scanner position system. The scanning process is performed at high speeds up to 60 m/min. Therefore, a reliable hardware trigger is required to obtain the real shape of the target.

Its compact design, integrated electronics and speed make the MicroEpsilon laser scanner suitable for inline integration. In addition, high performance scanners achieve a high repeatability of 50 µm/m even with different reflective properties of the metallic test objects.


Distance control of detectors for the examination of drill cores

For the geological analysis of drill core and mineral samples Cox Analytical Systems offers special X-ray analysis equipment (XRF scanners). These allow sample analysis for almost all elements of the periodic table in one measurement run. Micro-Epsilon scanCONTROL 2600 laser profile scanners were also integrated so that the systems work as quickly and accurately as possible.

In addition, these high-precision laser scanners not only provide information about the distance from the sample surface, but also about the surface profile (circular or flat) and the unevenness. This information is also processed in the analyser and is particularly useful for scanning samples without prior sample preparation.


Distance control in 3D printing

Micro laser sintering technology is an additive production technology based on digital 3D design data, whereby a component is constructed layer-by-layer from metal powders using a laser beam. This procedure is also known as industrial 3D printing. The exact positioning of the squeegee to the base surface (distance and tilt angle) requires an exact control method. Four CSE05(01) capacitive displacement sensors are used here. The planarity of the descending construction platform must be inspected before the process starts using three CS02 sensors integrated into an add-on module.


Distance measurements in robot positioning tasks

The car body must stop at exactly the intended position. This is the only way to ensure smooth installation via the robot, which must guide the cockpit between the A and B pillars into the vehicle. The correct position at which the car body should stop is determined by optoNCDT ILR1030-8/LC1 time-of-flight laser sensors from MicroEpsilon. They are particularly suitable for these and other comparable applications due to their short response time. The sensor is located on the same side of the assembly line as the assembly robot for cockpit installation. Measurements are taken at 100 Hz at the height of the A and B pillars of the vehicle and at a distance of approx. 600 to 700 mm.


Automatic height adjustment for material analysis

Laser-induced breakdown spectroscopy (LIBS) performs precise analysis of the atomic composition of different materials. The measurement objects involved are mostly mineral or metallic parts whose surfaces have different gloss levels and which are sometimes extremely tilted.

SECOPTA analytics GmbH uses the ILD1320-100 sensors from Micro-Epsilon in this application to automatically readjust the height of the LIBS sensor head. Particularly with metal samples whose surfaces have different texturessuch as oxidized spots, the ILD1320 with the ASC feature is a reliable sensor.


Web-edge detection in the calender of a paper machine

If movement of the paper web in the calender is not exactly executed in one line, the heated calender roller is pressed directly onto the coating of the opposite roller, which can damage it. Repairing this special coating or even replacing the whole roller would be very costly, which is why it is mandatory to control the position of the web edge. This is where laser line sensors from Micro-Epsilon are utilised, transferring the exact position of the web edge directly to the machine control system.


Measuring system for strip position monitoring in a coating tank

In the electrolytic refinement of thin sheets electrical losses are minimised by a small distance between strip and anode. This requires exact strip guidance. Before the strip enters the coating tank it is guided and measured between two measuring bars with nine eddy-current sensors each. Actuators are initiated and change the position of the anodes in accordance with the strip geometry, or initiate a return to the starting position if limit values are exceeded.


Sheet edge measurement prior to laser welding

The company „Paul von der Bank“ in Hilden (Germany) develops and manufactures modular-designed robotic welding cells and fully automatic production and processing lines. To ensure high production quality of longitudinally welded pipes, the following factors must be considered: Besides sheet edge length, the exact edge position must be known, it must be guaranteed that sheet edges are aligned perfectly to each other


Print head positioning using laser triangulation sensors

When printing on materials such as glass and ceramics, very fine detailed structures are generated, which requires precise positioning of the print head. This is why optoNCDT 1420 laser triangulation sensors from Micro-Epsilon are used. With a measuring range of 10mm, these determine at various points in the print head the respective distance from the surfaceto be printed. The sensor data is transferred via the RS422 interface to the control system. The data obtained enables the determination of the edges and the surface tilt and therefore the exact positioning of the print head.


Piston position detection in hydraulic cylinders

In order to detect the piston position of hydraulic cylinders, magnetostrictive and inductive sensors are normally factory-fitted in the sensor. A wide variety of sensors is required to cope with a huge number of different cylinder models (e.g. due to different strokes). Due to this, economies of scale are difficult to achieve.

Therefore, the magneto-inductive sensor (mainSENSOR) is an economic alternative that is mounted outside the cylinder while a magnet is integrated into the ferromagnetic piston rod. The face-mounted magnet transfers its magnetic field to the piston rod. The sensor then detects the magneticfield distribution along the rod and converts this into a linear output signal, which corresponds to the piston position.

In this way, measuring the piston position of a cylinder can be achieved (also retrospectively) in an extremely simple, space-saving way.


Precise positioning of a surgical microscope

Surgical procedures require a perfect view of the operating area. Here, the surgeon is often supported by a surgical microscope. To enable the surgeon to best position the microscope and to give the surgical team more room to move, the microscope optics are mounted to long arms on a stand.


Synchronization monitoring with draw-wire sensors in telescopic platforms

For electronic synchronization monitoring, a draw-wire sensor is used here. These are easy to integrate, very compact and offer high accuracy in addition to the large measuring range. For displacement measurement, the sensor is mounted on the lowest cylinder tube of the telescopic cylinder with the opening facing downwards. This prevents dirt or liquids from getting into the inside of the sensor. The steel cable with wire extension is guided from the sensor via deflection pulleys into the cylinder tube.

The sensor used is a type WDS-1500-P60-CR-P-M4 draw-wire displacement sensor with robust aluminum housing and a type WE-1500-M4 wire extension with M4 wire connection and 1500 mm wire length. In addition to the sensor used here, Micro-Epsilon provides a large number of other suitable draw-wire sensors for the same or similar applications, such as the MK77/MK60 series with a robust plastic housing.


High precision adjustment using capacitive sensors

In the production of thin-film solar cells, multiple functional layers are applied in a defined arrangement and structure onto glass sheets with a size of up to 3m x 5m. This happens in large coating systems. The uniformity of the coating depends on numerous process parameters. The distance between two perforated metal plates, which act as electrodes, is a key factor. These must be adjusted over the entire surface with an accuracy of at least 50µm. This is why continuous calibration and tests should ensure accurate positioning and arching correction. Therefore, a distance measurement is carried out in a vacuum at five different points. Previously, an external provider carried out timeconsuming and costly measurements using mechanical gages. LSAGmbH developed a new all-in-one solution involving non-contact, capacitive sensors from Micro-Epsilon which the system operator can use autonomously.

The capacitive sensor and the preamplifier are encapsulated under vacuum in a measuring box, which is used to measure the distance between the plates. In total, five sensors are connected to the capaNCDT 6500multi-channel system. The values measured are output via Ethernet.


Precise alignment of the cathodes at the electron accelerator

With its project “bERLinPro”, Helmholtz Zentrum Berlin [HZB] strives to develop a new technological basis for an “Energy Recovery Linac” (linear accelerator with energy recovery) in order to further develop accelerator technologies. Helmholtz Zentrum Berlin relies for this purpose on Micro-Epsilon’s precise measurement technology.

A photo cathode in a superconductive high-frequency electron gun is used to optimize the source of the electron bunches that are to be accelerated. During further acceleration, the electron bunches thereby generated remain more compact than bunches from other sources. This allows them to be used for achieving higher-quality X-rays, among other things. The electron source in the bERLinPro project is aligned by using three capacitive flat sensors together with a DT6220 controller. In the process, the tilting and change of the holder’s position during cooling from room temperature to 2 Kelvin (-271 °C) is monitored.


Measurement of the crankshaft position in grinding machines

This task involves the position measurement of the crankshaft with micrometer precision using eddy current-based inductive sensors. Both a continuous distance control and a consistent distance from the grinding tool are required. The analog sensor signal is therefore transmitted to a PLC. It adjusts the position of the grinding tool based on the measured values. Since cooling liquid (oil) is used for the grinding process, inductive sensors are perfectly suited. The application solution can also be integrated into existing systems as a retrofit.


Automatic paper roll control

In paper production the prepared paper pulp flows onto a conveyor belt of fine wire mesh at the so called "wet end". There most of the water is removed by means of a vacuum. The paper web is generated and is transported to the second station, the wet press rollers, which determine the paper web speed by means of a second drive unit. In order to avoid tears in the paper web a laser position measuring system is used here which measures the position of the paper web between the two stations. The analog output signal of the sensor is fed into a closed-loop control circuit which influences the motor speed at station 1 and thereby ensures that a specified setpoint distance value is maintained.


Distance measurement at 4 degrees Kelvin

In Atomic Force Microscopy (AFM), positioning units are used to move samples for surface topographies. In doing this, the sensor head of the microscope needs to be cooled down to four degrees Kelvin using liquid helium. Capacitive displacement sensors from the capaNCDT 6300 series are used to monitor these positioning units. The extremely flat design of the sensor enables it to be used in tight or restricted installations. Special materials with very low thermal expansion coefficients enable nanometre precision.


Automatic positioning of synchronizer discs

Synchroniser discs are used as a synchroniser package in automatic transmissions. Behr Systems in Germany created a handling and processing plant for deburring the front side of the synchroniser discs using a laser. An essential part of this plant is the measurement technology, which guarantees the precise positioning of the synchroniser discs under the deburring laser.


Positioning of operating tables

Operating tables provide many adjustment options for the correct positioning of the patient during the operation. As well as the height, the horizontal position and angle functions can also often be adjusted. As the positioning is performed electrically, the positions must be monitored. Draw-wire sensors from Micro-Epsilon are used for this.


Reliable quality control in the rolling mill

One of the profile rolling mills processes profile steel in reversing operation. The rod centre is then measured and evaluated using a  optoNCDT 1700-750BL.    


Position measurement on X-ray machines

For highres pictures of digital X-ray machines, the camera must be exactly adjusted to the X-ray tube. For pretty flexible operation, different axes are electrically moveable. Therefore, the adjustment of the camera to the X-ray tube can be as precise as possible, the positions of the axes are measured with draw wire sensors of the series wireSENSOR. With this gang control the camera and the X-ray tube can be moved parallel.


Reflector tilting for satellites

Satellites communicate with one another using laser beams. For this communication, the transmitter must be very precisely aligned with the receiver. The laser beam is stabilised using a deflection mirror. The position values are recorded with miniature eddy current sensors from Micro-Epsilon which achieve a resolution of better than one microrad. These sensors are also used in positioning tasks such as for laser tracking or lithography.


Tracking control of gantry and overhead cranes

Rail-guiding elements (wheel flanges, guide pulleys) ensure that the crane stays on the rails. Due to uneven distribution of mass, track errors, rails offset and different driving speeds, the rail-guiding elements can mesh. The lateral forces arising from this can lead to noise, stress in the crane construction or wear of the wheels and rails. Machines of this type require considerable maintenance. In order to reduce the latter, so-called tracking controllers are used in order to ensure that the crane wheels are kept central to the rail track. In this case, a number of sensors keep the controller informed about the position and direction of the crane, as well as any deviations that occur.


Control of the milling head in a mobile CNC milling unit

Thanks to their robustness and low weight, fiber-reinforced composite materials are increasingly used in the aviation and automotive industries. Maintenance and repair of such components are challenging tasks for repair shops. The damaged area must be removed layer by layer in order to enable the reconstruction of the laminate layer.

For repair work on airplanes, company SAUER GmbH developed the ULTRASONIC mobileBLOCK, which is a mobile 5-axis milling unit that enables repairs within just a few minutes. As the component can be damaged anywhere, the surface must be measured before the repair process starts. This is where SAUER relies on sensors from Micro-Epsilon.

In order to avoid collisions, the optoNCDT 1302 laser triangulation sensor measures the distance from the surface at a measuring range of 200mm. Subsequently, a scanCONTROL laser scanner measures the surface profile. Next, the program for the repair process is generated based on the  acquired 3D data.


Edge detection of fabric strips in the cutting machine

If the position of the material web is not recognized or is recognized incorrectly, this can result in waste from faulty cutting and machine malfunctions due to missing controller signals. Therefore, the optoCONTROL CLS-K-31 fiber optic sensor from Micro-Epsilon is used for position detection.

The sensor reliably detects the beginning of the roll. It is mounted directly on one of the cutting blades and recognizes from a distance of around 140 mm when the fabric is in the cutting position. A switching output (PNP) transmits a signal level directly to the controller and the cutting process begins. In this way, the cutting elements can be positioned exactly to 0.5 to 2 mm depending on the material. After each cut, the fabric position is recalculated. The measuring process is carried out at feed speeds of 20 m/min.

The optoCONTROL CLS-K-31 measuring system from Micro-Epsilon provides highly reliable and reproducible measurement results, which ultimately optimizes cutting accuracy, while reducing waste and process disruptions. The CLS-K-31 is even virtually insensitive to scratches and contamination on the shiny metallic surface of the roller.


Displacement detection of hydraulic diving platforms

Draw-wire sensors from Micro-Epsilon ensure that the towers are in the exact position, which is why the height is measured precisely. This is the only way to easily control this between 0.8 m and 3.5 m using a console on the edge of the pool. A wireSENSOR WDS-P115 draw-wire sensor is used on the diving platform, which detects the retraction and extension of the ladder. The current height of the diving tower is determined using these measured values.

The challenge lies in the high humidity, chlorine-containing environment and the high number of work cycles that the sensors must perform. The WDS-P115 industrial draw-wire sensor from Micro-Epsilon was therefore chosen. Due to their large measuring range, the robust aluminum profile housing and durable design with wear-free encoders, these modern industrial sensors deliver precise results even in demanding environments. They are also easy to install. In addition to the standard models, special versions with coated housings and rustproof stainless steel elements are available for extreme environmental conditions such as salt water.


Displacement sensor for nanopositioning tasks

Very small displacements, both static and dynamic, are normally generated by piezo actuators. High precision displacement sensors ensure that these displacements are measured to the required nanometre and sub-nanometre accuracies. Resolution and repeatability of up to 0.04nm are possible. Non-contact, capacitive displacement sensors from Micro-Epsilon provide this sub-nanometre precision. The capaNCDT series combines high precision and the required stability.