Machine building

Measuring tool holders in the magazine

Modern machine tools have complex magazines with various tools that are automatically picked up by the machine. In order for these tools to be accurately picked up, the tool holders must be precisely positioned. To check the position of the tool holders, optoNCDT 1420 laser sensors are used, which measure the metallic holders from above and from the side. These smart laser sensors stand out due to their high measuring rates while providing precise measurement values, despite strongly reflecting, metallic surfaces.

Nanometer positioning in lithography machines

To illuminate individual components on the wafer, the lithographic devices move the wafer to the respective position. Capacitive displacement sensors measure the position of the travel path in order to enable nanometer-accurate positioning.

Position measurement of the tailstock

The tailstock is an important part of a lathe or milling machine. The tailstock is used to support long workpieces by means of a centre, which catches in the centre hole on the front side of the workpiece. In order to detect the centre tip, compact draw-wire sensors from Micro-Epsilon are used. The measuring wire is connected to the centre tip and measures the displacement of the tailstock.

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Draw wire position sensors

Monitoring the clamping position of tools

Today, modern high-performance machine tools achieve accuracies in the micrometer range. Realising these levels of precision requires all components to be perfectly matched - from the drive to the release device via the tool clamp to the tool itself. Since most of the components are permanently installed on the machine, the highest precision can only be achieved if these were installed correctly. Only the tool is changed with each new operation and so can cause critical deviations. Particular attention should therefore be paid to the correct clamping of the tool in the holder. In any case, it needs to be detected whether the tool is correctly seated. When the position of the tool changes, this may result in poor machining quality, which would in turn lead to expensive workpieces that need to be scrapped. If the tool is tilted, it could become loose due to the high rotational speeds and cause a collision with other machine components.Often, initiators and switching rings, which provide a switching signal, are used to monitor the clamping position. However, these require complex adjustment and set up. Analogue sensors from the Micro-Epsilon LVP series offer significant improvements. The cylindrical sensor is integrated into the release device and directly measures the clamping stroke of the drawbar. On the drawbar, a ring is fastened, which acts as the target for the sensor. The LVP sensor can be universally used with the most varied types of tool due to an extremely compact sensor design. The sensor supplies an analogue signal according to the stroke motion of the drawbar when clamping the tool. Consequently, continuous monitoring is possible without the switching point having to be laboriously set mechanically. The miniaturised sensor electronic unit can either be accommodated at the point of measurement or in the control cabinet.Thanks to its high accuracy, the LVP sensor contributes significantly to meeting the ever increasing demands on machine tool precision and availability.

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Inductive sensors for specific applications

Measuring thermal length expansion of spindles

The SGS 4701 displacement measuring system (Spindle Growth System) is developed specifically for high speed milling machine applications. Due to high machining speeds and the heat generated, the linear thermal expansion of the spindle in the precision machine tool must to be compensated for in order to keep the tool in a defined position at all times. The SGS sensor measures the thermal and centrifugal force expansion of the spindle. These measurement values are fed into the CNC machine tool as correction values, compensating for any positioning errors. The SGS 4701 operates on the eddy current measuring principle. This non-contact measurement method is wear-free. Furthermore, the measurement procedure is resistant to disturbances such as heat, dust and oil.

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eddyNCDT SGS4701

Compensating for axial extension of milling spindles

Due to high machining speeds and the heat generated, the linear thermal expansion in milling spindles needs to be compensated for in order to keep the tool in a defined position at all times. The SGS sensor developed by Micro-Epsilon measures the thermal and centrifugal force expansion of the spindle. As well as measuring linear thermal expansion, the temperature of the sensor is also detected and output.

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eddyNCDT SGS4701

Foreign body detection in medical technology

Quelle: Uhlmann Pac-Systeme GmbH & Co. KG
Quelle: Uhlmann Pac-Systeme GmbH & Co. KG

In this application, the MDS sensor recognises foreign bodies in blister machines during the tablet packaging process. Via the movement of overhead touching rollers, foreign bodies between the blister packaging and covering material can be detected. Exceeding a pre-defined point triggers an alarm.

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Magneto-inductive displacement sensors

Valve lift measurement in the food industry

Quelle: SIG Combibloc Group AG
Quelle: SIG Combibloc Group AG

During the filling of drinks cartons, the exact dosage is a critical factor. The sensor measures the valve lift of the filling line and requests several switching points in a measuring range of 35mm. The sealed stainless steel housings of the MDS-45-Mxx series are ideal for the food industry.

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Magneto-inductive displacement sensors

Web-edge detection in the calender of a paper machine

Calenders are used in paper production and should improve the surface smoothness of the final product. To guide the paper web, the exact edge measurement is required. 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 the edges of the web enables the web width to be determined and to transmit this value to the next stage of the trimming process.

Monitoring oil gaps in hydrostatic bearings

Hydrostatic bearings are used in large plant and machinery such as stone mills, telescopic installations etc. Monitoring the gap size is a critical factor, as any disturbances in the hydraulics can cause pressure drops, which in extreme cases, can cause the gap to close, resulting in damage to the bearings and ultimately system failure. Here, it is important to have a system that is easy to install as also ageing plants have to be retrofitted. Due to the long service life and the worldwide use of this plant, the sensor should be easy to replace. For this reason, non-contact eddy current displacement sensors of the eddyNCDT 3001 series are used.

Active compensation for movements in the measurement process

Harsh industrial environments place high demands on optical displacement sensors – precise measurements must still take place despite dust and high processing speeds. The optoNCDT 1750 and optoNCDT 2300 series of laser sensors have been mastering these challenges for many years. However, if motion disturbances (e.g. belt movements, radial movements of pulleys, and base body vibrations) occur that are greater than the object being measured, the measurement process may be impeded or made impossible. Examples include folds in a belt.

Fluid level measurement of aluminium pig irons

In aluminium casting plants or foundries, the cast is poured into shape to form small bars, known as pig irons. The charging level in the forming process is critical in ensuring consistent weight of the pigs. Using a special non-contact measuring device, the depth of fill is recorded. For these applications, an Austrian system builder uses laser scanners. 

Measurement of the radial deviation of a cutter disk

During the manufacture of veneer strips from laminated wood, the precision of the cutting disk determines the quality of the final product. High demands are made on the veneer strips in terms of dimensional conformance. The thickness of the strips must be less than 1mm and may only exhibit tolerances in the micrometer range.

To maintain the quality criteria the radial deviation of the cutting disk is measured and monitored during the production process with a non-contact laser triangulation sensor from the Series optoNCDT 2300. This means that high demands are made on the measurement system: Dust, chippings and a shiny target surface must not affect the measurement accuracy.

Exact crusher gap adjustment in rotary crushers

Rotary crushers for quarries or ore mines can grind up to 3500 t of material to the desired grain size in one hour. For this purpose an eccentric bearing bush generates a rotary-oscillating movement of the crusher axle, thereby constantly changing the gap between the crusher jaws and the crushing cone. For grinding the set gap continuously moves along the inside perimeter of the crushing room. With a longdistance sensor in the hydraulic cylinder the crushing gap can be exactly adjusted by raising and lowering the axle.

Non-contact thickness measurement of aluminium

For the prompt detection of incorrect thickness on aluminium strip, patented laser triangulation sensors are employed as a modern alternative solution to isotope measurement systems. To save costs the places on the strip which are outside the permissible thickness tolerance are not provided with a foodstuffs-compatible coating and so the strip can be recycled without problem in production. At the point of measurement the sensors are mounted opposite one another, above and below the passing aluminium strip. Irrespective of the exact height position of the strip, the exact material thickness is obtained by a simple distance signal coupling, F=Ref. - (A + B), of both sensors.

Flatness measurement in rolling mills

The requirements on the surface quality of rolled sheet metal are continually increasing. This may be steel sheet which is used, for example, for stainless steel fronts in kitchens, or also aluminium sheet used in the automotive field. The surface must be flawless to offer the customer a high quality visual appearance. Consequently, measurement equipment is employed in rolling mills to acquire the so-called flatness of the rolled sheet metal. Flatness is taken to mean the surface evenness of the sheet in the unstressed state.

Yarn thickness

A consistent yarn thickness is a prerequisite in the textile industry for high quality products. Therefore, the naturally occurring yarn thickness fluctuations must be eliminated. The yarn is drawn to a constant thickness using a stretching tool. The measured data for controlling the stretching tool are provided by an eddy current sensor which indirectly measures the thickness. The thickness is transmitted to the eddy current sensor using sensing rollers. After the stretching, the result of the processing operation is also checked by an eddy current sensor.

Micro-Epsilon UK Ltd
No.1 Shorelines Building
Shore Road
CH41 1AU
+44 151 355 6070
+44 151 355 6075

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