Adapted hydraulic chuck as a problem solver

If sophisticated precision turned parts are to be fully machined in a process reliable manner, the basic components lathe, tools, tool clamping as well as the workpiece feed and clamping have to work in perfect unison. Nobody is more aware of this than the well-established Swiss company TORNOS SA in Moutier, which has dedicated itself to the development, manufacturing and servicing of automated lathes and later CNC lathes since its foundation in 1914. The current product range testifies to the innovative strength and performance of TORNOS’s 600 employees worldwide, of which 330 work at the parent plant in Moutier: The bar turning machine CT 20, the Swiss-type automatic lathes Swiss DT and Swiss GT, the highly productive Swiss-type automatic lathe EvoDECO, the multi-spindle lathe MultiSwiss, and the SwissNano specialist machines for micro and nano precision parts. On thousands of lathes, delivered around the world and used every day in industry, manufacturers and suppliers produce precision parts of the highest quality for medical technology, clock, micromechanic, electronic and automotive devices as well as assemblies and mechanical components. On the single- and multi-spindle lathes, precision parts of every conceivable degree of complexity can be machined from bars with a diameter of 4 to 32 mm. The multi-spindle lathes have up to eight spindles, nine CNC axles and 31 tools. Due to increasing component complexity in particular, caused by the integration of more and more functions and the simultaneous miniaturisation of workpieces, machine tool manufacturers frequently face big challenges, which they respond to by consulting outside specialists.

The successful collaboration between TORNOS SA and MAPAL Fabrik für Präzisionswerkzeuge Dr. Kress KG provides a very good example of an interdisciplinary cooperation between a machine manufacturer and a partner for original equipment with and continuous delivery of tooling solutions – here tool clamping technology in particular. When the standard tool clamping system used in the multi-spindle lathe MultiSwiss had problems extending hydraulic chucks for machining purposes, the construction and application engineers sought advice from the tool and clamping technology specialists at MAPAL. Andreas Mollet, MAPAL Regional Sales Manager Switzerland, describes the situation: “As a supplier of both tool and clamping technology, we can provide comprehensive solutions as a partner in this area. Our Centre of Competence for Clamping Technology in Ehrenfriedersdorf, Germany, is able to supply both standard and custom solutions. In this case, extending the standard hydraulic chuck system in use did not turn out to be practical because of the basic setting and positioning of the hydraulic chuck in the machine, among other things. This led to time-consuming retrofitting. Inaccuracies when changing positions also affected the reproducibility of machining precision.”  

After the HydroChuck hydraulic clamping technology product range was presented, which also includes hydraulic extensions, intense discussions took place to achieve an optimal solution. Due to other requirements regarding handling, setup, positioning, changeover accuracy, limited space in the working area, accessibility and more, the decision was made not to opt for a standard hydraulic extension but to develop a completely new hydraulic chuck. The extensions are designed to clamp tools with smooth cylindrical shanks – directly and without a reducing sleeve – in the clamping diameter and can be positioned freely on the machine side. This makes axial tool extension possible. It has an outer diameter of 25 mm and a clamping diameter of 12 mm, whereby this can be decreased to 2 mm with a reducing sleeve. This proved to be an ideal solution to the problem. Once position fixation in the connection of the machine is complete, the hydraulic chuck provides an exact reference point for all six to eight spindles of a MultiSwiss multi-spindle lathe.

Nicht nur davon überzeugt, meinte dazu Michel Rion, Process Engineer bei TORNOS SA: „Mit den Sonder-Hydrodehnspannfuttern von MAPAL verfügen wir jetzt über eine optimale Lösung, die unseren Anforderungen in jeder Hinsicht gerecht wird. Die verlängerten Hydrodehnspannfutter sind sehr einfach zu handhaben, das Rüsten und Positionieren geht viel schneller vonstatten, die Genauigkeit beim Wechseln ist gewährleistet, und wir können auch noch eine höhere, reproduzierbare Bearbeitungspräzision feststellen. Zudem sollte nicht unerwähnt bleiben, dass mit der Verlegung der Anschlüsse von seitlich nach hinten trotz der stark beengten Verhältnisse im Arbeitsraum eine sehr gute Zugänglichkeit für alle unproduktiven Rüstarbeiten gegeben ist, wodurch sich in Summe die Maschinenverfügbarkeit weiter erhöht.“ Mit dem erfolgreichen Einsatz der Sonder-Hydrodehnspanntechnik ist MAPAL ein weiteres Mal der Einstieg in die Erstausrüstung - diesmal von Drehmaschinen - geglückt. Zumal selbstredend auch bereits im Einsatz befindliche Drehmaschinen nachgerüstet werden können.