JPH0731044B2 - Machine motion accuracy measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention measures the accuracy of circular motion due to relative biaxial movement between a machine spindle and a table, such as machine tools and three-dimensional measuring machines. A motion accuracy measuring device.

The present invention relates to a simple motion accuracy measuring device, and more particularly to a device for measuring the accuracy of relative circular motion of a machine tool on the machine without actually cutting the work piece.

[Conventional technology]

Conventionally, when measuring the accuracy of circular motion due to relative biaxial movement between the tool spindle of a machine tool and a work table, the work (workpiece) is actually cut and the work is moved to another place. The roundness was actually measured by a roundness measuring device for measuring the object shape, and the accuracy of the circular motion of the machine tool was evaluated, and the circular motion program for operating the machine tool was corrected.

In addition, in the magazine "Precision Machinery" (June 1985 issue, pages 148 to 154) published by the Japan Society of Seiki Machinery, machine tools and three-dimensional measuring machines etc. directly show the relative position between the spindle and the table. As a device for measuring the accuracy of circular motion, a spherical seat was provided on the main shaft and table, and a measuring bar having spheres at both ends was attracted to both spherical seats by magnets to perform relative circular motion, and was incorporated inside the measuring bar. A strain gauge is disclosed that measures the momentary displacement amount between the spindle and the table from the strain generated when the measurement bar is constrained and moves circularly.

[Problems to be Solved by the Invention]

 Each of the above-mentioned conventional methods has the following problems.

In the former case, two steps of cutting the workpiece and actually measuring the roundness are required for one measurement, and it takes a lot of man-hours to measure under different conditions.

Since the cutter radius is not zero, the movement trajectory of the tool spindle itself does not transfer to the surface to be cut.
It is not possible to accurately evaluate the relationship between the stick motion that occurs when the quadrants of the XY axes are changed and the behavior of the tool spindle.

There was a problem such as.

Further, in the latter case, a spherical seat having a magnet attracting means and a special measuring bar having a sphere at both ends and a strain gauge incorporated therein are required, but this fabrication is difficult and expensive.

Since both ends of the measuring bar are constrained by spherical seats, the measuring bar normally tilts, and the displacement cannot be obtained unless such a cosine error is corrected.

There was a problem such as.

The object of the present invention is to reduce the accuracy of the circular motion due to the relative biaxial movement between the main spindle of the machine and the table, without the need to actually cut the work piece, to make it compact and lightweight, to be portable, and to have a simple structure at low cost. It is an object of the present invention to provide a motion accuracy measuring device that is easy to handle and can measure quickly.

[Means for Solving the Problems]

The present invention uses a relative orthogonal 2 between the spindle 1 and the table 10.
In a machine motion accuracy measuring device for measuring motion accuracy of circular motion due to axial movement, a master disk 3 mounted coaxially with the spindle 1 and a master disk 3 on the table 10 are arranged substantially parallel to the axis of the master disk 3. 5a, which is freely supported on the housing 4 by the diaphragm 8 and is provided with a balanced centripetal action by the plurality of springs 7, and the contact portion 5a of the measuring bar 5 with the master disk 3. Between the main shaft 1 and the table 10 while displacing the measuring bar 5 by bringing the rolling member provided in the above, the outer circumference of the master disk 3 and the measuring bar 5 into contact with each other via the rolling member. It is characterized in that it is provided with two displacement detectors 6X, 6Y for detecting the displacement of the measuring bar 5 in the orthogonal biaxial movement when the circular movement is performed by the relative orthogonal biaxial movement.

[Action]

According to the present invention, when the master disc mounted on the main shaft makes relative circular motion while pressing against the measuring bar on the table side, the measuring bar is always rotated by the master disc at all positions of this relative circular motion. Will receive a force in the normal direction. The measuring bar is free-supported by the diaphragm so that the adverse effect of frictional force is eliminated, centripetal action is given by a plurality of balanced springs, and rolling resistance with the master disk is reduced by the rolling member. As a result, the measuring bar is always displaced in the normal direction of the outer circumference of the master disk, and the displacement of the measuring bar at a predetermined position is continuously detected by the detector. By guiding this detection output to an oscilloscope or the like, the circular motion accuracy can be visually observed.

〔Example〕

FIG. 1 is a block diagram of an embodiment of the present invention. In the figure, 1 is a tool spindle of a machine tool, 2 is a shank portion 2a which is inserted into a taper hole of the tool spindle 1, a holder for fixing a master disk 3 first, and 4 is fixed on a table 10. Housing 5 is a measuring bar, 5a is an abutting portion with the master gauge 3 provided on the upper portion of the measuring bar 5, 5b is a spherical portion at the lower end of the measuring bar 5, 6X, 6Y
Is a proximity sensor for displacement measurement, and two proximity sensors for X-axis and Y-axis are provided at an angle of 90 ° to each other.

Since the proximity sensor is fixed to the housing 4, it is possible to continuously measure circular motion data for many rotations.

It is also possible to measure the motion accuracy in a steady state in which the circular motion speed is stable by rotating it multiple times.

Reference numeral 7 is an elastic body for supporting the measurement bar 5, which is formed of, for example, a coil spring, 8 is a diaphragm, and 9 is a damper fin. The housing 4 is filled with oil for obtaining a damper effect, and the damper fins make the oil dumping effect uniform.

Further, the outputs of the proximity sensors 6X and 6Y are input to the amplifier 11, and the amplified X-axis output and Y-axis output are connected to the horizontal and vertical input terminals of the oscilloscope 12 for waveform observation. The display waveform of the oscilloscope is recorded by the Polaroid camera 13, for example.

Since the contact portion 5a on the upper portion of the measuring bar 5 has a ball bearing structure using a ball bearing with respect to the center axis of the measuring bar as shown in the figure, friction against the pressing of the master disk 3 is minimized. The impact can be reduced.

As shown in the figure, the measuring bar 5 is provided with a plurality of coil springs 7 having a constant spring constant in equal distribution, so that the displacement-contact characteristics in the XY plane are supported in a uniform balance with no directivity in the displacement direction. There is. By adjusting the balance position with the left and right balance adjusting screws 7a, the measuring bar 5 due to the influence of gravity when the measuring device is installed vertically
It is also possible to compensate for this. The center of the diaphragm 8 has a pivot point P which serves as a fulcrum for the operation of the measuring bar 5. Since the distance from the point P to the centers of the contact portion 5a and the sphere portion 5b is equidistant, the radial displacement of the contact portion 5a is the displacement of the sphere portion 5b on the opposite side with the pivot point P as the fulcrum.

The measuring bar 5 supports the pivot point P by elastic deformation of the diaphragm 8 and centripetal action by elastic deformation of the coil spring 7. Therefore, since the movable portion of the measuring bar 5 has no rattling or friction portion, a displacement operation without hysteresis is possible.

The fact that the master disk 3 mounted on the spindle 1 moves relative to the measurement bar 5 supported on the table 10 while making a relative circular motion means that the contact portion 5a of the measurement bar 5 is in the XY plane. It is equivalent to continuously receiving a force in the normal direction from all directions and continuously displacing it. As a result, in combination with the actions of the ball bearing, the coil spring, and the diaphragm 8 described above, the measurement bar 5 has the master disk 3 at the contact portion 5a.
It is accurately displaced in the normal direction of the outer circumference.

FIG. 2 is an example of displacement data displayed on the oscilloscope. In the above-mentioned configuration, when the master disc is slightly pressed against the measurement bar 5 to give a pre-displacement to the measurement bar 5, a relative circular motion of radius R is performed between the master disc 3 and the measurement bar 5 in that state. The displacement generated in the contact portion 5a is detected by the proximity sensors 6X and 6Y as the displacement of the spindle of the machine tool through the spherical portion 5b, and is displayed on the oscilloscope after amplification. Since two proximity sensors, 6X for X-axis and 6Y for Y-axis, are provided, the X-axis shown in the figure will be displayed on the display screen without any calculation processing by a personal computer.
The displacement data detected on the axis side and the displacement data detected on the Y axis side are combined and displayed as a Lissajous figure.
The whiskers 14 at the time of switching each quadrant are due to the amount of backlash and the stick motion at the time of axis switching.
Therefore, these amounts can be measured by the size of the mustache 14. The amount of displacement of the Lissajous figure thus obtained from the circle is obtained as a relative circular motion error.

〔The invention's effect〕

As described above, according to the present invention, the accuracy of the circular movement due to the relative biaxial movement between the main shaft of the machine and the table is accurately measured in a short time without actually cutting the work. be able to. Further, the motion accuracy measuring device has a simple structure, is small and lightweight, and is excellent in portability. And you just have to place it on the table,
Easy to handle. Even if complicated data processing is not performed, the circular motion locus can be displayed on the screen as a Lissajous figure only by using an oscilloscope, and data collection can be easily performed.

[Brief description of drawings]

 FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a display example of displacement data. (Explanation of symbols) 1 ... Tool spindle, 2 ... Holder, 3 ... Master disk, 4 ... Housing, 5 ... Measuring bar, 5a ... Abutting part, 5b ... True sphere, 6X, 6Y ... Proximity sensor, 7 ... Coil spring, 8 ... Diaphragm, 9 ... Damper fin, 10 ... Table, 11 ... Amplifier, 12 ... Oscilloscope, 13 ... Camera.

Claims (1)

[Claims] 1. A motion accuracy measuring device of a machine for measuring motion accuracy of circular motion by relative orthogonal biaxial movement between a main shaft (1) and a table (10), wherein the device is coaxial with the main shaft (1). Mounted master disc (3)
On the table (10), the housing (4) is freely supported by the diaphragm (8) so as to be substantially parallel to the axis of the master disk (3), and balanced by the plurality of springs (7). And a rolling member provided at the contact portion (5a) of the measuring bar (5) provided with the centripetal action, and the master disk (3) of the measuring bar (5), and the master disk (3). The outer circumference of the measuring bar (5) and the measuring bar (5) through the rolling member, and the measuring bar (5)
The spindle (1) and the table (10) while displacing
Two displacement detectors (6X, 6Y) for detecting the displacement of the measuring bar (5) in the directions of the two orthogonal axes when a circular movement is performed by relative two-axis movements relative to each other. A machine motion accuracy measuring device characterized by being provided.