Patent Application
20070167111
The present invention relates to precision machine tools for machining flat parts of different materials.
More particularly, it relates to precision grinding of parts composed of glass, ceramic, semi-conductors and other materials.
Machine tools of the above-mentioned general type are known in the art. Such machine tools is disclosed for example in Soviet inventor's Certificates Nos. 390,924 and 622,650. They are used for grinding flat parts and include a rotary table with a changeable flat plate for attaching parts to be machined on its base surface, and a rotatable abrasive tool. The machine tools disclosed in these references have an orientation mechanism which is in contact with the base surface of the pivotal flat area of the changeable flat plate. The orientation mechanism includes two rings with bearing balls located between them. One ring is non-rotatable, while the other ring rotates in contact with the pivotal area of the flat blade. The above-mentioned machine tools have certain disadvantages. The device is limited to the sizes of the rings and do not allow building of orientation mechanisms of greater dimensions with flatness on the rings about 1 micron or less, since greater diameters require greater flatness tolerances of the parts to be machined. It is advisable to improve the machines tools of this general type.
Accordingly, it is an object of the present invention to provide a precision machine tool which is a further improvement of the existing precision machine tools of this type.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a precision machine tool which has a spindle for driving a tool; a table for placing a work piece; and an orientation mechanism including at least three orientation elements, each of the orientation elements being formed by a plurality of rolling bodies which are capable of continuously rolling on a surface of the table during operation of the machine tool.
When the precision machine tool is designed in accordance with the present invention, it eliminates the disadvantages of the prior art.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
A precision machine tool in accordance with the present invention has a lower spindle which is identified as reference numeral 1 and supporting lower plate 2 which, through a ball 3 supports an upper plate 4 of a swivelable table 5 having an upper surface for supporting work pieces.
At least three orientation elements 6 are provided around an axis of the table and attached by bolts 7 to a holder 8. Springs 9 urge an upper spindle 10 to a wedge 11. A motor 12 moves the wedge 11 and thereby the spindle 12 which carries a tool 13 formed as a grinding tool, a polishing tool, etc. Work pieces 14 are supported on an upper surface of the table. The holder 8 is arranged in the guide 15 which in turn is supported on a column 16.
The orientation elements 6 are shown in
Reference numeral 20 identifies yieldable holders which hold the ball in a lateral direction and allow its lateral displacement within a limited range. They also hold the balls in the guide before the orientation elements are placed on the table. Reference numeral 21 identifies springs and bolts 22 allows adjustment of the position of the balls in all orienting elements relative to one another.
Since the orientation elements include the above-mentioned plurality of rolling bodies, the orientation is performed in a reliable manner, there is no limitation as to the size and accuracy of the orientation elements, and the accuracy of orientation of the table is substantially increased.
It will be understood that each of the constructions described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.
While the invention has been illustrated and described as embodied in a precision machine tool, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.
