Precision Machines with Mechanical Bearings

In cases where higher demands exist regarding the precision and long-term stability of machines (for example, in the metrology lab and in production control), special new design approaches must be taken. Aluminum is used as a structural material to improve the controllability of temperature problems. Its high thermal conductivity minimizes differences in temperature, thus reducing deformation of the machines. In order to prevent changes in the tension of the guideway systems caused by expansion, a special system is used in which prestress is produced by means of magnetic force and gravity (Fig. 29).

Fig. 29: Constant-tension guideway system of Werth measuring stages.

Moreover, this guideway system also minimizes friction, reducing backlash on reversal as well. For the same reason, housing covers that produce friction are generally avoided. The long-term stability of the system is further supported by the fact that the guideways are produced without any manual adjustment. They are precision-manufactured with variations of less than one micrometer. Figure 30 shows such a machine.

A new image processing sensor mechanism featuring a Werth Zoom lens system (combining high flexibility with maximum accuracy) is included as basic equipment.  A continuous-path control provides the system with scanning capability and enables optional retrofitting of a laser sensor (Foucault principle), a three-dimensional measuring probing system or the Werth Fiber Probe. If required, motorized probe heads for the probing systems or rotational axes for the workpieces can be used to extend the operative range of machines of this class. In order to ensure that the measuring uncertainties of less than 2 µm attainable with these systems can be fully achieved, it is advisable to install them in an enclosure with reduced temperature fluctuations for in-process measuring applications. The requirements for implementing machine encapsulation are not, however, very high.


 

Fig. 30: Desktop model (Werth VideoCheck® 400×200×200).