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The TC76 probe system from Blum-Novotest has been selected by automotive manufacturer Saarstahl to simplify the process of measuring carbide rings.

Saarstahl is a traditional company that specialises in the production of wire rods, steel rods and semi-finished parts plus contour forgings.

Customers include the automotive, construction, energy, aerospace and general mechanical engineering industries.

In spring, the company took delivery of a turn/grind centre from EMAG.

The VSC 400DS had a special task: to combine turn/grind machining of carbide roll rings and carry out measuring operations to optimise the production process.

By means of an integrated measuring system, the workpieces should be measured between manufacturing steps and the tools checked indirectly.

The diameter on the carbide ring is collected with a probe system, compared with the target data and then turned to the correct diameter.

If the diameter is finished, the calibre position and depth are measured, then re-measured after pre-turning, turned to size and then the dimensions should be accurate.

’In the beginning we underestimated measurement as we had no previous experience of this approach,’ said Michael Molter, a technician at Saarstahl.

The circumferential grooves on the carbide ring together with the ring grooves on the counter-roll are the profile of the roll product, called the calibre.

The carbide ring has two calibres and can be mounted on both sides.

Therefore, each front side must be the same distance to the centre line of the calibre otherwise there will be an offset.

The calibres of the carbide rings work with wires from 8.5-25mm diameter with a tolerance of +/-0.15mm.

Previously, every carbide ring was measured offline after machining at a measuring station with a height measuring device.

This complex task should have been taken over by the new turn/grid centre, credit to a probe system for machine integrated measurement supplied by EMAG.

To collect the precise position of the calibres, trigger contacts must be carried out on the complex geometries.

The first probe provided only moderate repeatability, which was a real problem that created lobing measuring characteristics with different deflection forces.

The staff therefore defined a correction value for each calibre and incorporated it into the following measurement and checked the values offline at the measuring station.

Andreas Braun, roll machining manager at Saarstahl, said: ’The probe system was accidentally destroyed and replaced by a new one from the same manufacturer.

’Both probe systems had such wide tolerances that our staff had to redefine the correction values.

’They had to interpolate the data to get the approximate target values.

’Measurement with the electronic height measuring device on the measuring position failed, too.

’Sometimes the values were within the tolerance, sometimes outside of the tolerance.

’We had no in-process quality,’ he added.

Due to the extent of the problems, a design engineer from EMAG proposed an alternative from Blum-Novotest – its TC76 probe system.

The system was developed to measure workpieces and tools in turning and grinding machines, so no sooner had the system been mounted, all measuring accuracies disappeared.

Uwe Fischer, sales engineer at Blum-Novotest, said: ’Inside the TC76 is the patented Shark 360 measuring mechanism with a face gear.

’This guarantees precise trigger contacts and forces in all directions.

’The probe has precise non-lobing touch characteristics even for measurements with torsion forces on the mechanism,’ Fischer added.

Another advantage is the no-wear trigger signal generation of the Blum probe.

The TC76 generates an optoelectronic signal by shading a miniature light barrier on the inside of the probe and not according to the tripod principle.

Since being integrated into the turn-grinding centre, the Blum probe reliably measures and Molter can now abandon time-consuming correctional alterations.

The values are repeatable and random checks of the carbide rings are performed.

Therefore, the requested in-process quality was guaranteed.

The considerably higher measuring speed with the Blum probe (up to 2m/min) reduced the measuring process time by 40 per cent.

The probe checks the tools indirectly via workpiece measurement, so that the manual intermediate measurements are now automated.

Blum-Novotest said the TC76 and turn/grinding centre are complementing each other perfectly.

With the previous machining centre the carbide ring had to be taken from the machine and measured offline, reset and re-machined.

With the EMAG machine the complete ring can be turned in one setting.

If a cutting plate has wear and the probe displays that the tolerance is exceeded, the turn-grinding machine compensates this wear automatically and turns to the correct size.

Measurement is carried out before the final cut and the tool is corrected correspondingly.

The staff at Saarstahl can now rely on the probe in hot summer or cold winter weather with no deviations.

Staff had no introduction or training period and according to Braun the program was installed and left to work.

Neither maintenance nor contact to the Blum service department was necessary as the probe is working perfectly.

Blum-Novotest GmbH is recognized as a developer of leading-edge measurement and testing technology, with some 40 years of experience as partner for the worldwide machine tool, automotive and aircraft industries.

The business develops and produces tactile and optical measuring systems for workpiece measurement and tool setting applications in machine tools. Alongside this, Blum develops and manufactures production line integrated measuring and testing solutions.

In addition to the modern, fast growing manufacturing sites near Ravensburg (Germany, BW) and Willich (Germany, NRW) Blum has sales & service subsidiaries in Bordeaux, Como, Birmingham, Cincinnati, Los Angeles, Japan, Taiwan, Korea, Singapore and Shanghai.

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