Measuring and testing – Dynamometers – Responsive to force
Patent
1989-11-30
1991-08-27
Ruehl, Charles A.
Measuring and testing
Dynamometers
Responsive to force
73104, 7386268, 408 11, G01L 512
Patent
active
050423096
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to apparatus and method for sensing a thrust load applied to a spindle of a machine tool.
BACKGROUND OF THE INVENTION
In conventional machine tools, sensing operations such as tool breakage sensing and tool wear sensing are performed by sensing the thrust load applied to a spindle of a machine tool. Thus cutting control of the machine tool may be adapted to the detected present conditions.
In the above-mentioned conventional methods for sensing the thrust load, the power of a spindlehead feed motor or the thrust load applied to a feed screw is taken as (substituted for) the thrust force applied to the spindle.
However, in case of sensing the power of the spindle-head feed motor or the thrust load applied to the feed screw, not only tool cutting resistance but also other frictional resistances such as frictional resistance against rotation within bearing support for a ball screw and sliding friction resistance applied to the spindlehead are also sensed at the same time. Accordingly, it is necessary to calculate a value representative of tool wear/breakage, e.g. by subtraction of frictional forces from the sensed power value. Thus, the sensing of tool wear/breakage tends to have low accuracy.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to provide an apparatus and method for directly sensing the thrust load applied to a spindle of a machine tool, by which the thrust load alone can be sensed with a high degree of accuracy, to the exclusion of other forces such as tool cutting resistance and frictional resistances.
Accordingly, the machine tool of the present invention includes a frame, a spindlehead, a cylindrical spindle support mounted within the spindlehead and a spindle mounted on thrust bearings within the cylindrical spindle support. Pressure sensors are positioned between abutting surfaces normal to the axis of the spindle. For example, a pressure sensor may be positioned between flange on the spindle support and an annular seat surrounding the opening in the spindlehead which receives the spindle support, between an annular shoulder within a central bore of the spindle support and a surface on one of the bearings and/or between a flange ring bolted through a flange on the spindle support to the frame and the flange of the spindle support.
Upon application of a thrust load to the spindle support, each of the pressure sensors, preferably in the form of annular sensors coaxial with the spindle, will generate a signal representing the thrust load alone.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a side view showing a machine tool adapted in accordance with the present invention for sensing the thrust load on the machine tool spindle;
FIG. 2 is a sectional view showing portion of the spindlehead of the machine tool FIG. 1;
FIG. 3 is a sectional view showing one type of pressure sensor which may be employed in the present invention;
FIG. 4 shows a pressure sensor, in the form of a piezo-electric film, which may be used in the present invention; and
FIG. 5 is a sectional view showing a spindlehead of another machine tool which may be used for the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a machine tool including a bed 1, table 2, column 3, spindlehead 4 and motors 5, 6, 7 and 11.
A workpiece W is set on the table 2. The table 2 is moved in the X-direction by the motor 5. The column 3 is moved in both the Y.sub.1 and Y.sub.2 directions by the motor 6. The spindlehead 4 is moved in both the Z.sub.1 and Z.sub.2 directions by the motor 7.
A toolholder 10 is detachably secured to the spindle 12 of the spindlehead 4. The toolholder 10 is rotated together with tool 13 by the motor 11.
Referring to FIG. 2, FIG. 2 shows one embodiment of the present invention, in the form of a spindlehead 4. The spindle 12 is rotatably supported by a cylindrical support portion 20 with thrust bearing 16, 17 and 18. In addition, a cap member 21 is attached to the lower end of the support portion 20 by means of bo
REFERENCES:
patent: 2978689 (1961-04-01), Tech et al.
patent: 3208311 (1965-09-01), Pierce
patent: 3872285 (1975-03-01), Shum et al.
patent: 4133206 (1979-01-01), Hida et al.
patent: 4741231 (1988-05-01), Patterson et al.
Kitamura Machinery Co. Ltd.
Ruehl Charles A.
LandOfFree
Apparatus and method for sensing a thrust load applied to a spin does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for sensing a thrust load applied to a spin, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for sensing a thrust load applied to a spin will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1406523