JP2987607B2 - 3D coordinate measuring machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional coordinate measuring machine for measuring three-dimensional coordinates of a contour of various machined parts and the like.

[0002]

2. Description of the Related Art As a three-dimensional coordinate measuring machine of this kind, X.
A touch probe is attached to the moving head of the YZ axis moving mechanism, and a linear scale for detecting the position of the X, Y, and Z axes is provided on each of the X, Y, and Z axes, and the surface of the object to be measured is touched. When the probe is contacted, the X, Y, and Z axes
2. Description of the Related Art A measuring device is known in which a microcomputer takes in position data from a linear scale and stores three-dimensional coordinate data of an outline of an object to be measured.

[0003]

However, in the case of a conventional three-dimensional coordinate measuring machine of this type, when a high-precision measurement is to be performed, the structure of the X, Y, and Z-axis moving mechanism is changed, for example, by using a rigid bridge. It is necessary to increase the rigidity of the moving mechanism and to make the structure firmly large, such as by adopting a gantry (gate-shaped) structure. With a small and simple X, Y, and Z axis moving mechanism, measurement errors are not small. This causes a problem that high-precision measurement is difficult to be performed. In addition, the X, Y, and Z axis moving mechanisms that move the X, Y, and Z axes linearly move the three axes by manually holding the moving head. There has been a problem that manual measurement is difficult to perform efficiently and easily.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and uses a relatively small moving mechanism having a simple structure to easily and efficiently measure three-dimensional coordinates without errors with high accuracy. It is an object of the present invention to provide a three-dimensional coordinate measuring machine that can be used.

[0005]

In order to achieve the above object, a three-dimensional coordinate measuring machine according to the present invention comprises: a rotary column vertically rotatably provided on a measuring table; and a rotation angle of the rotary column. A rotary encoder that outputs an angular position signal in accordance with the above, a horizontal arm that protrudes to one side and is fixed horizontally at the upper end of the rotating column, and a horizontal arm that is disposed on the horizontal arm so as to be movable in the horizontal direction. A moving unit, a horizontal linear encoder that outputs a horizontal position signal indicating a moving position of the horizontal moving unit, a Z-axis moving unit vertically movably disposed in the horizontal moving unit, and a movement of the Z-axis moving unit A vertical linear encoder that outputs a Z coordinate signal indicating a position, a tracing stylus attached to a moving head provided in a part of the Z-axis moving unit, and a tip that comes into contact with an object to be measured on the measurement table;
An auxiliary leg attached to the end of the horizontal arm at a right angle toward the surface of the measurement table; and an auxiliary leg attached to the end of the auxiliary leg via a coil spring so as to be movable up and down and abutting on the surface of the measurement table. A sliding slider, a gap sensor for detecting the height of the gap between the tip of the auxiliary leg and the slider, and detecting the height of the gap between the tip of the auxiliary leg and the slider. A gap sensor, and corrects horizontal position data from the horizontal linear encoder and data of a Z coordinate signal from the vertical linear encoder based on detection data output from the gap sensor, and corrects the horizontal position data and the rotary encoder. And data processing means for calculating the X coordinate and the Y coordinate from the rotation angle position data from.

[0006]

[Operation / Effect] In the three-dimensional coordinate measuring machine having such a configuration, when measuring the three-dimensional coordinates of the contour shape of the measured object,
An object to be measured is placed on a measurement table, and its position is arbitrarily moved by holding a moving head, so that the tip of a tracing stylus contacts the surface of the object to be measured. At this time, the moving head, that is, the tracing stylus is moved by the rotation of the rotary column together with the linear movement of the horizontal moving unit and the Z-axis moving unit. In comparison with the method, the tracing stylus can be moved more easily and lightly, and the work efficiency of measurement is greatly improved.

[0007] When the input switch is turned on by the contact of the tracing stylus with the object to be measured or manually, the data processing means takes in detection signals from the rotary encoder, the horizontal linear encoder, the vertical linear encoder, and the gap sensor.

Further, the data processing means corrects the data of the horizontal position signal from the horizontal linear encoder and the data of the Z coordinate signal from the vertical linear encoder based on the detection data output from the gap sensor, and corrects the horizontal position. The X coordinate and the Y coordinate are calculated from the signal data and the rotation angle position data of the rotary encoder.

In the three-dimensional coordinate measuring machine having such a structure,
With the horizontal arm being cantilevered, errors in measured values due to deformation of the rotating column and horizontal arm are likely to occur,
Since the horizontal position data and Z coordinate are corrected from the data of the height of the gap (corresponding to the deformation of the rotating column and the horizontal arm) output from the gap sensor provided at the tip of the auxiliary leg, those errors are properly corrected. Thus, accurate measurement data can be obtained.

Further, as described above, since the detection data is corrected, it is not necessary to increase the processing accuracy and rigidity of each part of the measuring machine including the rotating column and the horizontal arm so much, and the measuring machine can be manufactured at low cost and in a simple manner. Can be manufactured.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of the main body of the three-dimensional coordinate measuring machine, and FIG. 2 is a front view thereof. Reference numeral 1 denotes a measurement table (surface plate) on which an object to be measured is placed.
At the upper end of the (table), a rotating column 2 is rotatably set up on a vertical axis as a rotating axis. A rotary encoder 10 is provided at a rotating portion of the rotary column 2 so as to output a signal corresponding to the rotation angle position of the rotary column 2.
This rotary encoder is an absolute encoder and outputs a signal indicating an absolute angular position.

Further, a horizontal arm 3 is fixed horizontally above the rotary column 2. At the distal end of the horizontal arm 3, an auxiliary leg 6 is fixed vertically to the horizontal surface of the horizontal arm 3 and the table 1. The horizontal arm 3 has a horizontal moving unit 4.
Are disposed so as to be slidable in the horizontal direction, and a Z-axis moving unit 5 is attached to the horizontal moving unit 4 so as to be vertically slidable.

A horizontal linear encoder 11 for outputting a signal corresponding to the moving position is provided in the horizontal moving unit 4. The horizontal linear encoder 11 is an absolute encoder and outputs a signal indicating an absolute position.

Further, the Z-axis moving section 5 is provided with a vertical linear encoder 12 for outputting a signal corresponding to the moving position. The vertical linear encoder 12 is an absolute encoder and outputs a signal indicating an absolute position. A weight balancer (not shown) for applying a heavy load upward including the Z-axis moving unit 5, the moving head 9, and the tracing stylus 15 is disposed in the horizontal moving unit 4. The Z-axis moving unit 5 is configured to be able to stop at an arbitrary position.

As the rotary encoder 10, the horizontal linear encoder 11, and the vertical linear encoder 12, for example, an optical or electromagnetic rotary scale or linear scale is used.

Further, as shown in FIG. 4, a slider 7 that slides on the measuring table 1 is attached to the lower end of the auxiliary leg 6 via a coil spring 8. The slider 7 is pressed onto the measurement table 1 by a slight urging force of the coil spring 8, and can slide easily. Lower end of auxiliary leg 6 and slider 7
Is formed between them.

At the lower end of the auxiliary leg 6, the gap C
The gap sensor 13 is attached to detect the height α. As the gap sensor 13, for example, an electromagnetic position sensor is used, and outputs a signal indicating the position of the slider 7 formed of a magnetic material, that is, a signal indicating the height α of the gap C. Since the height α of the gap C changes according to the deflection of the rotary column 2 and the horizontal arm 3, it is used to correct an error in measurement data caused by the deflection of the rotary column 2 and the horizontal arm 3.

A moving head 9 is fixed to the lower end of the Z-axis moving section 5, and a tracing stylus 15 and a handle 16 are attached to the moving head 9. The tracing stylus 15 has a structure in which, for example, a touch sensor type input switch 14 is built in, and when the tip of the tracing stylus 15 touches the surface of the device under test, the input switch 14 operates to output a signal. When a touch sensor type switch is not used, an input switch may be attached to the outside of the moving head 9, and the switch may be manually operated to input measurement data.

Since the three-dimensional coordinate measuring machine having such a structure has a structure in which the rotary column 2 rotates, the rotation angle of the column is defined as θ, and the position data of the horizontal moving section 4 on the horizontal arm 3 (from the origin) As shown in FIG. 3, the X coordinate on the X axis is obtained from X = Rcos θ, and the Y coordinate on the Y axis is obtained from Y = Rsin θ, as shown in FIG. Can be Also, Z on the Z axis
The coordinates are position data of the Z-axis moving unit 5 (output position data of the vertical linear encoder).

As shown in FIG. 5, the data processing circuit of the three-dimensional coordinate measuring machine is constituted by a microcomputer as a main part, and a CPU 20 controls a tracing stylus 15 based on program data stored in a ROM 21 in advance. After correcting the X-, Y-, and Z-axis coordinate data measured by manual operation, a process of sequentially storing the data in the RAM 22 is performed.

The rotary encoder 10, horizontal linear encoder 11, vertical linear encoder 12, gap sensor 13, and input switch 14 are connected to an input / output circuit 25 of a microcomputer. Display 2 such as CRT
3, a printer 24 and a keyboard 25 are provided.

As described above, the height α of the gap, which varies according to the deflection of the rotary column 2 and the horizontal arm 3, is detected by the gap sensor 13, and the position data R corresponding to the height α of the gap C is detected. The correction value KRn and the correction value KZn of the Z coordinate are measured in advance according to the position data R and the Z coordinate.
21 is stored as a data table.

The correction values KRn and KZn are determined in advance by measuring the three-dimensional coordinates of a known object such as a master gauge using the above-described three-dimensional coordinate measuring machine, and determining the error of the measured values. The error is determined to be corrected according to the data of the gap height α obtained from the gap sensor 13, the correction value KRn is set as table data corresponding to the position data R of the horizontal moving unit, and the correction value KZn is set as the Z coordinate. Is stored as table data in correspondence with. Therefore, when correcting the position data R, R = R + KR
When correcting the n and Z coordinates, Z = Z + KZn may be set.

Next, the operation of the three-dimensional coordinate measuring machine having the above configuration will be described.

When measuring the three-dimensional coordinates of the device under test, the device under test is placed on the measurement table 1 and the data processing circuit is put on standby. Then, by holding the handle 15 provided on the moving head 9 and arbitrarily moving its position,
Contact the surface of the object to be measured. Since the three-dimensional movement of the moving head 9 is performed by the movement of the horizontal moving unit 4 and the Z-axis moving unit 5 including the rotation of the rotary column 2, the moving head 9 can be moved lightly and easily manually.

At this time, the input switch 14 in the tracing stylus 15
Is turned on, and an input signal is sent to the CPU 20. CPU2
When the input signal is inputted, the detection signal is read from the rotary encoder 10, the horizontal linear encoder 11, the vertical linear encoder 12, and the gap sensor 13.

Then, the CPU 20 obtains a correction value KRn from the data table in the ROM 21 from the height α of the gap C fetched from the gap sensor 13 and the horizontal position data R fetched from the horizontal linear encoder 11.
The horizontal position data R is corrected from the equation of R + KRn. Similarly, from the height α of the gap C taken from the gap sensor 13 and the Z coordinate data taken from the vertical linear encoder 12, the correction value KZn is obtained from a data table in the ROM 21, and the equation of Z = Z + KZn is obtained. To correct the Z coordinate data.

Next, the horizontal position data R corrected as described above and the angular position data θ from the rotary encoder 10 are
Is used to calculate the X coordinate from the equation of X = Rcos θ,
The Y coordinate is calculated from the equation of Y = Rsinθ. Then, each data of the calculated X coordinate, Y coordinate, and Z coordinate is stored in the RAM.
Write to 22.

Thereafter, when the moving head 5 is moved and the tip of the tracing stylus 15 contacts the surface of the object to be measured again, the input switch 14 is turned on, and the CPU 20 operates the rotary encoder 10, the horizontal linear encoder 11, and the vertical linear encoder 11. New detection signals are fetched from the encoder 12 and the gap sensor 13, the horizontal position data R and the Z coordinate are corrected from these detection data, and the X coordinate, the Y coordinate, and the Z coordinate are calculated, and the calculated X coordinate is calculated. , Y coordinate, and Z coordinate are written in the RAM 22. By repeating such an operation, the three-dimensional coordinates of the measured object are measured and stored.

As described above, the horizontal moving unit 4 and the Z-axis moving unit 5
The moving head 9, that is, the tracing stylus 15 is moved by the rotation of the rotary column 2 together with the linear movement of the tracing stylus 15. It can be moved, and the work efficiency of the measurement can be greatly improved.

When the horizontal arm 3 is of a cantilever type, an error in measured values is likely to occur due to the deformation of the rotary column 2 and the horizontal arm 3, but the error is output from the gap sensor 13 provided at the tip of the auxiliary leg 6. In order to correct the horizontal position data R and the Z coordinate from the data of the height α of the gap C (a value corresponding to the deformation of the rotating column 2 and the horizontal arm 3), those errors are corrected and accurate measurement data is obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main body of a three-dimensional coordinate measuring machine showing one embodiment of the present invention.

FIG. 2 is a front view of the measuring device.

FIG. 3 is an explanatory diagram showing values of an X coordinate and a Y coordinate.

FIG. 4 is an enlarged sectional view showing a gap sensor and a slider provided at the tip of an auxiliary leg.

FIG. 5 is a block diagram of a data processing circuit of the measuring instrument.

[Explanation of symbols]

 1-measurement table, 2-rotation column, 3-horizontal arm, 4-horizontal moving section, 5-Z-axis moving section, 6-auxiliary leg, 7-slider, 8-coil spring, 9-moving head, 10 -Rotary encoder, 11-horizontal linear encoder, 12-vertical linear encoder, 13-gap sensor.

Claims (1)

(57) [Claims] 1. A rotary column vertically rotatably mounted on a measurement table, a rotary encoder for outputting an angular position signal according to a rotation angle of the rotary column, and one end on one end of the rotary column. A horizontal arm protruding from the horizontal arm and fixed horizontally, a horizontal moving unit disposed movably in the horizontal direction on the horizontal arm, and a horizontal linear encoder for outputting a horizontal position signal indicating a moving position of the horizontal moving unit A Z-axis moving unit disposed vertically movable in the horizontal moving unit; a vertical linear encoder that outputs a Z-coordinate signal indicating a moving position of the Z-axis moving unit; and a part of the Z-axis moving unit. A measuring element attached to the moving head provided at the end of the horizontal arm, and an auxiliary leg attached to the end of the horizontal arm at a right angle toward the surface of the measurement table; The A slider that is vertically movably attached to the tip of the auxiliary leg via a coil spring and slides in contact with the surface of the measurement table; and the height of the gap between the tip of the auxiliary leg and the slider. A horizontal position data from the horizontal linear encoder and data of a Z coordinate signal from the vertical linear encoder based on the detection data output from the gap sensor. A three-dimensional coordinate measuring machine comprising: data processing means for calculating X and Y coordinates from rotation angle position data from the rotary encoder.