KomTronic® U-axis systems now also have a direct encoder


Even if you only take into account their low weight yet minimal size and the relatively large adjustment path for the tool, the new generation of KOMET KomTronic® U-axis systems already represents the latest state of development. With a modular system, the KOMET GROUP is now offering a supplemental direct encoder. In comparison with the normal indirect encoder, this offers significantly improved repeat accuracy, which also characterises the mechatronic tool systems by KOMET®  as state-of-the-art products.


The mechatronic KOMET KomTronic®  U-axis systems essentially consist of one compact facing head with a single slide which is driven by a servo motor and threaded spindle. The power supplied to the electronics and the drive is transmitted contact-free and inductively to the U-axis system. Similarly, the data is exchanged inductively with the U-axis system. A so-called stator is mounted on the spindle side. It is segment-shaped, which permits the tools to be replaced automatically. The ring-shaped inductive transmission unit (rotor) on the U-axis side ensures reliable data and energy transfer in every angular position, even when coolant is being used. The mechatronic U-axis systems are therefore automatically exchangeable NC axes. Thanks to the freely programmable cutting edge, which can be dynamically adjusted during machining, they can be used to carry out all types of contour machining and lathing on parts without rotational symmetry. To enable this, the U-axis is interposed with the Z-axis of the machine. Through the combined use of customised snap-on tools and optimally selected indexable inserts, it is possible to machine contours in bores as well as external contours. The mechatronic tool systems enable a significant shortening of production times, better surface quality, and improved dimensional accuracy. In addition, fewer different tools are required and there is no need to procure moulding tools.


Flexibility straight from the toolbox


The development state of the  KOMET KomTronic® U-axis systems in the standard range of the KOMET GROUP  is substantially based on the technology project of KOMET KomTronic® HPS (High-Precision Systems) for high-speed machining. Here, the main aim is to increase speed, which requires - among other things - compact designs with lower weights. "In addition to focusing on the miniaturisation of designs, modularisation - as a means of increasing flexibility and enhancing ranges of use - is also important to us" explains Dr.-Ing. Jürgen Fronius, Head of the Mechatronics Division of the KOMET GROUP . Fronius clarifies the current state of development by comparing the tried-and-trusted UAS-160/125 variant with the new generation. The evolved design of the UAS-125 for HSK63 interfaces is still in demand for applications with non-critical interference contours and in machines with appropriate tool changer weights. With a weight of 7.6 kilogrammes and a head diameter of 125 millimetres, turning contours of up to ±6 millimetres per stroke can be achieved. In contrast, the UAS-115 of the new KomTronic generation weighs only 6.4 kilogrammes and enables an impressive stroke of ±11 millimetres with a head diameter of just 115 millimetres.


Fronius explains that the drive unit, a module miniaturised as part of the development of the HPS project, plays an important role in the compact nature of the design: "The motor unit and adjustment mechanism are integrated into a base body."  The current facing slide module is adapted in line with this. Components for energy and data transfer complete the U-axis system. Along the same lines, there are HSK100 designs in addition to the HSK63 variant. The modular system means that these two head sizes enable the realisation of several U-axis variants with different sizes and weights and different radial strokes of 22 or 50 millimetres.


1:1 position measurement on slider


A direct encoder was another result of the HPS technology project: This was first presented by the KOMET GROUP at AMB 2010. Usually, mechatronic tool systems are fitted with an indirect encoder which is integrated into the drive unit. The new direct encoder can now also take into account interferences resulting from the mechanics, ranging from the motor shaft and gearbox to the threaded spindle. The direct measurement system allows measuring right on the slider followed by a reaction with the control system. Although precision was already high, this still constitutes yet another significant improvement in repeat accuracy. This is associated with better methods for compensating for progressive wear. Fronius adds the following: "If you combine the two encoders, you can set up a wear/condition check for examining position differences/backlash over time". The fact that this optional method of position measurement can be chosen by customers on request is another advantage of the consistent modular philosophy of the KOMET GROUP, a mindset which is applied to the standard range of KOMET KomTronic®  U-axis systems. Examined from this point of view, the modular nature of these mechatronic tool systems can also be said to be a state-of-the-art characteristic.

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Trade press:

Wolfgang Klingauf

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