JP2012058057A - Gage for three-dimensional coordinate measuring instrument and precision evaluation method for three-dimensional coordinate measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gage for three-dimensional coordinate measuring instrument that is constituted more easily with higher precision, and a precision evaluation method using the gage for three-dimensional coordinate measuring instrument.SOLUTION: The gage 1 for three-dimensional coordinate measuring instrument for evaluating precision of a three-dimensional measuring instrument is constituted by including a first sphere 4 and a second sphere 5 fixed on a surface of a substrate 3, and a third sphere 6 fixed on a first column 7 provided protruding from the surface of the substrate 3.

Description

  The present invention relates to a gauge for a three-dimensional coordinate measuring machine and a method of using the same.

Conventionally, a three-dimensional coordinate measuring machine has been used for quality inspection of various precision parts. In addition, with the recent improvement in the quality of precision parts, there is an increasing demand for higher accuracy for quality inspection.
In order to meet such a demand, Patent Document 1 discloses a gauge in which a sphere is fixed to the surface of a block gauge, and a method of using the gauge. Further, Patent Document 2 discloses an inspection body for a coordinate measuring apparatus that includes a base body on which spheres having different heights are held.
See also Patent Document 3 which discloses the prior art related to the present invention.

JP 2000-180103 A JP-A-2-67902 JP 2003-302202 A

Many precision parts that are measured using a three-dimensional coordinate measuring machine are also handled. Therefore, accuracy evaluation in the height direction is also required for accuracy evaluation of the three-dimensional coordinate measuring machine.
On the other hand, as in Patent Document 2, if the number of parts constituting the gauge is increased in order to enable various precision evaluations, it is likely that deviation between parts is likely to occur, and the reliability of precision evaluation is reduced. It is done.
Further, as a JIS standard, JIS B 7440 that defines an accuracy test method for a three-dimensional coordinate measuring machine is provided. However, when the test is performed, there is a problem that the test cannot be easily performed, for example, it takes a long time for preparation and an inspection method for setting the gauge to a constant temperature.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have made it possible to evaluate the accuracy of a three-dimensional coordinate measuring machine with higher accuracy and more simpleness, which enables evaluation close to JIS standards. The present invention has been conceived.
That is, the first aspect of the present invention is defined as follows.
A gauge for evaluating the accuracy of a three-dimensional coordinate measuring machine,
A substrate having a flat upper surface, a first sphere array disposed on the upper surface of the substrate,
A three-dimensional coordinate measuring machine gauge, comprising: a second sphere array arranged to be inclined with respect to the upper surface of the substrate.

According to the three-dimensional coordinate measuring machine (hereinafter sometimes simply referred to as “measuring machine”) gauge of the first aspect defined as described above, two sphere rows are arranged on one substrate. Once the substrate is set on the coordinate measuring machine, the accuracy of the coordinates can be evaluated at least with respect to the arrangement direction of the first and second sphere rows with the gauge set.
In view of the ease of setting the gauge with respect to the measuring apparatus, the substrate is preferably a rectangular flat plate. In this case, the first sphere row is arranged along one side of the substrate, and the second sphere row is viewed in plan on the substrate. It is preferable to arrange them on a diagonal line (second aspect).
Along with the ease of setting the gauge to the measuring device, changing the posture of the gauge makes it possible to measure more data in more directions or positions, and in the same direction and position. Reliability of evaluation is improved.

In order to evaluate the accuracy in more directions with the gauge set, the number of sphere rows may be increased.
However, as the number of spheres increases, the movement of the probe of the measuring machine is restricted. According to the study of the present inventor, it is preferable that the number of spheres is about 2 to 5.
In the presence of the first and second sphere rows described above, it is preferable that the third sphere row is disposed on the upper surface of the substrate so as to be orthogonal to the first sphere row (third aspect).
From the viewpoint of changing the attitude of the gauge and easily obtaining more data, the substrate is a rectangular flat plate, the first sphere array is arranged along one side, and the other side (perpendicular to the first side) It is preferable that the third sphere row is arranged along the first sphere row and the length of the third sphere row is different from the length of the first sphere row (fourth aspect).

Each sphere row includes at least two spheres, and the start point and the end point of the sphere example are determined by the two spheres.
Each sphere row can share one or more spheres.
It is also possible to adopt a configuration in which each spherical body row is set on a retainer and this retainer is fixed to the substrate. By arranging a large number of spheres in the retainer, a large amount of data can be acquired for accuracy evaluation.
It is preferable that stress is not applied to the retainer when the retainer is fixed to the substrate. This is because if the retainer serving as the standard device is stressed, the retainer is distorted and the distance between the spheres changes.

If the substrate having a sphere array along the upper surface of the substrate and the sphere array arranged to be inclined with respect to the upper surface of the substrate is rotated, the accuracy evaluation of the length in any direction can be performed.
Accordingly, another aspect of the present invention is defined as follows.
A method of evaluating the accuracy of the three-dimensional coordinate measuring machine by illuminating the error of the three-dimensional coordinate measuring machine obtained using the gauge described above in light of a relationship between a predetermined length and an allowable error,
(1) fixing the gauge to the three-dimensional coordinate measuring machine, and specifying the length between spheres included in each sphere row based on the output of the three-dimensional coordinate measuring machine;
(2) a calculation step of comparing the length between the specified spheres with a reference value prepared in advance and calculating a first error;
Evaluating the accuracy of the coordinate measuring machine using the error calculated in the calculation step (2);
A method for evaluating the accuracy of a three-dimensional coordinate measuring machine, comprising:

If the substrate is changed to various postures, it is possible to evaluate the accuracy of the length in the direction corresponding to the directions V1 to V7 defined in JIS B 7440.
Therefore, another aspect of the present invention is defined as follows. That is,
The installation posture with respect to the three-dimensional coordinate measuring machine is changed, and step (1) and step (2) described above are repeated,
Extracting from the calculated errors first to seventh direction-specific errors having directions corresponding to directions V1 to V7 defined in JIS B 7440;
Evaluating the accuracy of the three-dimensional coordinate measuring machine using the first to seventh direction-specific errors;
A method for evaluating the accuracy of a three-dimensional coordinate measuring machine, comprising:

The following is proposed as a gauge that can efficiently and accurately evaluate the length in the direction corresponding to the directions V1 to V7 defined in JIS B 7440.
That is, the gauge specified in the fourth aspect,
The first sphere row includes a first sphere A and a second sphere B;
The second sphere row includes the first sphere A and the third sphere E;
The third sphere example includes the first sphere A and the fourth sphere D,
Furthermore, a fourth sphere row comprising the first sphere A and the fifth sphere C is provided, and the fourth sphere row is inclined with respect to the substrate in a direction different from that of the second sphere row. is doing.

It is a figure which shows direction V1-V7 prescribed | regulated to JISB7440. It is a figure which shows schematic structure of the three-dimensional coordinate measuring machine gauge of embodiment of this invention. It is a figure which shows schematic structure of the three-dimensional coordinate measuring machine gauge of the Example of this invention. It is a block diagram which shows the structure of the precision evaluation apparatus using the three-dimensional coordinate measuring machine gauge of the Example of this invention. It is a flowchart explaining operation | movement of an accuracy evaluation apparatus similarly. It is a schematic diagram which shows the attitude | position of the three-dimensional coordinate measuring machine gauge of an Example. It is a figure explaining the evaluation reference | standard based on the difference (error) of reference | standard length and measurement length. It is a schematic diagram which shows the other attitude | position of a three-dimensional coordinate measuring machine gauge. It is a schematic diagram which shows the other attitude | position of a three-dimensional coordinate measuring machine gauge. It is a figure which shows schematic structure of the three-dimensional coordinate measuring machine gauge of another Example. It is sectional drawing which shows the structure of a 1st mount. It is sectional drawing which shows the structure of a 2nd mount frame. It is a figure for demonstrating the three-dimensional coordinate measuring machine gauge of FIG. 3 from a spherical-array viewpoint. It is a figure which shows schematic structure of the three-dimensional coordinate measuring machine gauge of another Example.

A three-dimensional coordinate measuring machine gauge according to an embodiment of the present invention will be described.
FIG. 2 shows a schematic configuration of the three-dimensional coordinate measuring machine gauge 1 of the present invention.
As shown in FIG. 2, the three-dimensional coordinate measuring machine gauge 1 includes a substrate 3, a first sphere A, a second sphere B, a third sphere E, and a first column 7.
The shape of the substrate 3 is not particularly limited as long as the substrate 3 has mechanical strength for holding the sphere and the column and can secure stability when set on the three-dimensional coordinate measuring machine. It is preferable that it is a flat plate rectangular shape from the handling property at the time of accuracy evaluation work.
The shape of each sphere can be arbitrarily designed as long as the probe of the CMM can contact any surface from any direction and its center position can be accurately specified, but it must be a true sphere. Is preferred. Although the size can be arbitrarily designed, it is preferably about 10 to 30 mm.
The shape of the column is not particularly limited as long as it can stably hold the sphere at a position away from the substrate. In the embodiment, a rectangular column shape is used, but the cross-sectional shape may be a circle, an ellipse, or a polygon other than a rectangle. Further, the cross-sectional shape can be deformed in the axial direction. Hollow pillars can also be used.
If the sphere can be held away from the substrate, an arbitrarily shaped ridge (eg, a hump) may be provided on the surface of the substrate instead of the pillar, and the sphere may be set at any point of the ridge, preferably at the top. Good.
In other words, the pillar is a means for stably fixing the sphere at a predetermined position on the surface of the substrate.

The first sphere A and the second sphere B are fixed to the surface of the substrate 3. The positions of the first sphere A and the second sphere B are not particularly limited, but are preferably arranged along one side of the substrate 3 and more preferably located at adjacent corners.
Further, the third sphere E is fixed on the first pillar 7 provided so as to protrude from the surface of the substrate 3. By using such a three-dimensional coordinate measuring machine gauge 1, it is possible to evaluate the accuracy of the length in the plane and also to evaluate the accuracy in the height direction. In the three-dimensional coordinate measuring machine gauge 1, when a fourth sphere D described later is provided, the third sphere E includes a first straight line connecting the first sphere A and the second sphere B, The first sphere A and the fourth sphere D are preferably located in a first region sandwiched by a second straight line that connects the second sphere B and the fourth sphere D. It is preferable to be located on the straight line.

The three-dimensional coordinate measuring machine gauge 1 may include a fourth sphere D, a fifth sphere C, and a second column.
The fourth sphere D is preferably fixed on the surface of the substrate 3. Further, the position of the fourth sphere D is not particularly limited, but the first straight line connecting the first sphere A and the second sphere B and the first sphere A connecting the first sphere A and the fourth sphere D. The two straight lines are preferably arranged so as to be orthogonal to each other, and more preferably arranged along one side of the substrate 3. Moreover, it is preferable to arrange the fourth sphere D so that the length of the first straight line is different from the length of the second straight line. If accuracy evaluation corresponding to different lengths is performed in this way, the reliability of accuracy evaluation is improved.

  The fifth sphere C is fixed on the second pillar provided so as to protrude from the surface of the substrate 3. Although the position of the fifth sphere C is not particularly limited, the fifth sphere C is located in a second region sandwiched between the extension line of the first straight line and the extension line of the second straight line, and the first sphere A and the third sphere C It is preferably located at a position deviating from the virtual extension line connecting to the sphere E, and more preferably at a corner corresponding to the opposite corner of the corner where the first sphere 4 is located. Moreover, it is preferable that the height of the 1st pillar 7 and the height of a 2nd pillar differ. If accuracy evaluation corresponding to different heights is performed in this way, the reliability of accuracy evaluation is improved.

The substrate, sphere and column are preferably formed of a material having a low thermal expansion coefficient, and more preferably formed of a material having a thermal expansion coefficient of 0.05 or less. As such a material, for example, a trade name (NEXCERA) provided by Nippon Steel Corporation can be used. This material has a coefficient of thermal expansion of substantially zero at room temperature. If a material with a low coefficient of thermal expansion is used, it is not necessary to consider the temperature expansion of the three-dimensional coordinate measuring machine gauge due to temperature, and the time required for preparations such as temperature break-in to keep the gauge constant This is because it becomes unnecessary and the time required for accuracy evaluation work can be shortened. In addition, if the coordinate measuring machine gauge is made of a material with a low coefficient of thermal expansion, there will be no temperature difference at the components in the gauge, or non-uniform temperature expansion that occurs even at a constant temperature. Since a gauge having extremely high shape retention performance can be obtained, the reliability of accuracy evaluation is improved.
Of course, any material whose thermal expansion coefficient (preferably in the three-dimensional direction) at the operating temperature can be accurately specified can be temperature-corrected, so a material having a thermal expansion coefficient exceeding 0.05 can be used. It is.

FIG. 3 shows a schematic configuration of a three-dimensional coordinate measuring machine gauge 20 according to another embodiment of the present invention. 3, the same elements as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is partially omitted.
3 includes a substrate 3, a first sphere A, a second sphere B, a third sphere E, a fourth sphere D, a fifth sphere C, and a first column. 7 and the second pillar 23.
In this three-dimensional coordinate measuring machine gauge 20, the substrate 3 is formed in a planar rectangular shape. By making the substrate rectangular, the handleability is improved when performing accuracy evaluation work.

The first sphere A is fixed to the first corner on the surface of the substrate 3. The second sphere B is fixed to the second corner adjacent to the first corner on the surface of the substrate 3.
In the fourth sphere D, the first straight line connecting the first sphere A and the second sphere B and the second straight line connecting the first sphere A and the fourth sphere D are orthogonal to each other. , And arranged along one side of the substrate 3. It is preferable that the length of the first straight line is different from the length of the second straight line. In the three-dimensional coordinate measuring machine gauge 20, the second straight line is half the length of the first straight line. The 4th spherical body D is arrange | positioned. Thus, if the accuracy evaluation corresponding to different lengths is performed, the reliability of the accuracy evaluation is improved.

  The third sphere E is fixed on the first pillar 7 provided so as to protrude from the surface of the substrate 3. The third sphere E is preferably located in a first region sandwiched between the first straight line and the second straight line. In the three-dimensional coordinate measuring machine gauge 20, the third sphere E is the second sphere E. The sphere B and the fourth sphere D are located on a third straight line.

  The fifth sphere C is fixed on the second pillar 23 provided so as to protrude from the surface of the substrate 3. The fifth sphere C is preferably located in a second region sandwiched between the first straight line extension line and the second straight line extension line. In the three-dimensional coordinate measuring machine gauge 20, The sphere C of 5 is located at the third corner corresponding to the diagonal of the first corner where the first sphere A is located. The height of the first column 7 and the height of the second column 23 are preferably different. In this three-dimensional coordinate measuring machine gauge 20, the second column 23 is twice as high as the first column 7. It is configured to be. Thus, if the accuracy evaluation corresponding to different heights is performed, the reliability of the accuracy evaluation is improved.

  If this three-dimensional coordinate measuring machine gauge 20 is used, it will correspond to the directions of V1 to V7 prescribed in JIS B 7440 by measuring the gauge 20 in four postures rotated 90 degrees at the time of accuracy evaluation. Each length can be measured several times. In this way, the number of position changes during the accuracy evaluation work can be reduced, and it is possible to evaluate the accuracy based on multiple measurements in one direction. It is possible to implement.

Next, an accuracy evaluation method using the three-dimensional coordinate measuring machine gauge 20 of FIG. 3 will be described.
FIG. 4 is a block diagram showing the accuracy evaluation apparatus 300, and FIG. 5 is a flowchart showing the accuracy evaluation method. FIG. 6 shows the posture of the gauge 20 when executing the accuracy evaluation.
The accuracy evaluation apparatus 300 includes three memories 31, 32, and 33. The reference data memory 31 stores the coordinates, center distance, and direction of the center of each sphere of the gauge 20 measured by a predetermined method. These coordinates are obtained, for example, by precise measurement by the Measurement Standards Center of Tsukuba National Institute of Advanced Industrial Science and Technology. The origin of the gauge 20 can be arbitrarily set. For example, the coordinates of the first sphere (A in FIG. 6) can be used as the origin.

The directions between the spheres may or may not correspond to the directions V1 to V7 defined in JIS B 7440.
These relationships are shown in Table 1.

The measurement data memory 32 stores the coordinates of each sphere of the gauge 20 measured by a three-dimensional coordinate measuring machine that is an object of accuracy evaluation. In this embodiment, the coordinates of the center of each sphere are stored at four positions (postures) when the substrate is rotated 90 degrees with the center of the substrate of the gauge 20 as the rotation center. The origin of the coordinates is preferably matched with the reference data stored in the reference data memory.
The length calculation unit 36 calculates the length between the spheres based on the coordinates of the center of each sphere stored in the measurement data memory 32. The calculated length is stored in the inter-sphere length / direction storage unit 39 together with the direction as the measurement length.

The measurement length and direction at each position are shown in Tables 2 to 5 in association with the directions V1 to V7 defined in JIS B 7440.

The error calculator 41 calculates the difference between the reference length and the measured length between the same spheres as an error. The calculation result is stored in a buffer memory (not shown) in association with each measurement length.
The V1-V7 extraction unit 42 extracts an error corresponding to the directions V1 to V7 defined in JIS B 7440.
Data regarding the directions of V1 to V7 necessary for this extraction is stored in the evaluation data memory 33 in advance.
In this example, seven directions are selected based on the provisions of JIS B 7440, but as shown in Tables 1 to 5, data other than the V1 to V7 is also stored for the length between the spheres and the direction thereof. ing. Therefore, the reliability of accuracy evaluation can be further improved using such data. In this case, the extraction target data is set and saved in advance in the evaluation data memory 33.

The extracted error data is sent to the evaluation unit 43, and it is determined whether or not the error value is within an allowable range.
Since the error value increases as the length between the spheres increases, the error value should be evaluated in relation to the reference length. In this example, it is evaluated whether the error is within the allowable range using the relationship shown in FIG. In FIG. 7, the vertical axis indicates the error (mm), and the horizontal axis indicates the reference length (mm) between the spheres.
It can be evaluated that the error data within the range between the straight lines in FIG. 7 is within the allowable range (◯), and the data that is out of the straight line is out of the allowable range (×). In addition, it is possible to arbitrarily set a certain range band around the straight line, and evaluate the data in the range as caution (Δ).
The evaluation criteria (straight line position and inclination) are also stored in advance in the evaluation data memory 33 and can be arbitrarily set by the user.
The evaluation result of the evaluation unit 43 is sent to the output unit 47. The output unit 47 displays the evaluation result on the display and prints it out.

Next, the operation of the accuracy evaluation apparatus 300 according to the embodiment will be described based on the flowchart of FIG.
It is assumed that the reference data shown in Table 1 has been acquired in advance.
In step 1, the gauge 20 is set in the position A in FIG. Then, the coordinate measuring machine is operated to specify the coordinates of the center positions of the spheres A to E (step 3). Based on the measured coordinates, the length between the spheres is calculated and stored in a buffer memory (not shown) (step 5). At the same time, in step 7, the direction between the spheres whose length has been calculated is also specified, and similarly stored in a buffer memory (not shown) in association with the measured length.

In step 9, the error calculator calculates the error between the reference length between spheres (see Table 1) and the measured length between spheres.
This embodiment proposes an accuracy evaluation method capable of ensuring at least the same accuracy as the accuracy evaluation based on JIS B 7440. For this purpose, a length component in the same direction as the directions of V1 to V7 is extracted. Extracted by the unit 42 (S11). As described above, the extraction target can be arbitrarily selected.
In step 13, the error between the spheres and the reference length are plotted in FIG. 7, and the evaluation is determined based on whether or not the plotted data is within the range surrounded by the pair of straight lines in FIG.

Next, the gauge 20 is set in the position B by rotating the board 90 degrees clockwise around the center of the board (see FIG. 6).
Thereafter, steps 3 to 13 in FIG. 5 are repeated to collect error data.
Similarly, error data at positions C and D is collected.
As is apparent from Tables 2 to 5 described above, error data corresponding to all of the seven directions V1 to V7 defined in JIS B 7440 are not obtained at each position. However, if the data collected at the four positions are integrated, two or more error data can be secured in all directions of V1 to V7.
Here, for example, by setting the cage 20 on the rotary table of the coordinate measuring machine (positioning the center of the substrate of the gauge 20 on the rotation center of the rotary table), the position of the gauge 20 is changed. This is an extremely easy task.
The position change that the gauge 20 can take is not limited to the example of FIG. 6, and as shown in FIG. 8, the rotation center can be set at one corner of the substrate. Further, as shown in FIG. 9, the position of the substrate can be changed in the vertical direction.

FIG. 10 shows a gauge 30 of another embodiment.
The gauge 30 includes a rectangular flat substrate 33, a first sphere array 40, and a second sphere array 140.
The first sphere array 40 is disposed along one side of the substrate 33. The first sphere array 40 has a rectangular rod-shaped retainer 41 having a constant cross section, and five spheres 43-1 to 43-5 are arranged at equal intervals on the upper surface thereof.
The shape of the retainer and the number of arranged spheres can be arbitrarily designed.
The retainer 41 is placed in each recess of the first gantry 60 and the second gantry 70.

  The first mount 60 has a first protrusion 61 at the center of the lower surface thereof. The lower end of the first protrusion 61 (contact portion with the substrate 33) is formed in a hemispherical shape. Side surfaces of the first gantry 60 are tapered surfaces 63 and 64, and the fixed rod 66 and the movable rod 68 abut against the tapered surfaces 63 and 64. By projecting the movable rod 68 toward the first gantry 60, the first gantry 60 is fixed to the substrate 33, but no force is applied to the retainer 41. Reference numerals 65 and 67 denote support members for the fixed rod 66 and the movable rod 68, respectively.

The second mount 70 has a first protrusion 71 and a second protrusion 72 at the center of the lower surface thereof. The lower ends of the protrusions 71 and 72 (contact portions with the substrate 33) are formed in a hemispherical shape. Side surfaces of the first pedestal 70 are tapered surfaces 73 and 74, and the fixed rod 76 and the movable rod 78 abut against the tapered surfaces 73 and 74. By projecting the movable rod 78 toward the first gantry 70, the first gantry 70 is fixed to the substrate 33, but no force is applied to the retainer 41. Reference numerals 75 and 77 are support members for the fixed rod 76 and the movable rod 78, respectively.
The retainer 41 is placed on the substrate 33 in a stable state by the first protrusion 61 of the first base 60 and the first protrusion 71 and the second protrusion 72 of the second base 70.

The configuration of the second sphere array 140 is also the same as that of the first sphere array 40, and the same elements are denoted by the same reference numerals and description thereof is omitted.
Reference numeral 50 in the figure denotes an auxiliary substrate, which is inclined with respect to the substrate 33 by the first pillar 51 and the second pillar 53. The second sphere array 140 is fixed to the auxiliary substrate 50.
In such a gauge 30, only the retainer 40 and the sphere need be formed of a material having a low coefficient of thermal expansion.
When such a gauge 30 is set in a measuring machine, the coordinate error of the measuring instrument, that is, the side length error can be measured in the arrangement method of the first sphere array 40 and the second sphere array 140, and the accuracy can be evaluated. .

In FIG. 10, each sphere is fixed to the upper surface of each retainer 41 in the first sphere array 40 and the second sphere array 140. Therefore, the first sphere row and the second sphere row are independent.
When the gauge 20 shown in FIG. 3 is viewed from the viewpoint of the sphere array, as shown in FIG. 13, the first sphere array composed of the first sphere A and the second sphere B, the first sphere A and The second sphere array composed of the third sphere E, the third sphere array composed of the first sphere A and the fourth sphere D, and the first sphere A and the fifth sphere C. It can be seen that a fourth sphere array composed of
Here, it can be seen that the first sphere A is shared in each sphere row.

FIG. 14 shows a gauge 80 of another embodiment.
The gauge 80 includes a rectangular flat substrate 33 and a spherical plate 90.
The sphere plate 90 includes a first sphere row 100 and a second sphere row 110.
The first sphere row 100 includes four spheres 100-1 to 100-4 arranged at equal intervals on the upper surface of the sphere plate 90, and the first sphere row 100 is arranged along one side of the substrate 33. Is done.
The second sphere array 110 includes spheres 110-1 to 110-3 that share the sphere 100-1 as the first sphere array 100 and are arranged at equal intervals from the sphere 100-1.
The shape of the spherical plate 90 is not particularly limited as long as the first spherical row 100 and the second spherical row 110 can be integrally provided.
In addition, the code | symbols 91 and 93 in a figure are a latching claw, and can fix the one end side of the spherical board 90. FIG. The gauge 80 includes a column 95 for inclining the spherical plate 90.
If such a gauge 80 is set in a measuring machine, it is possible to measure the coordinate error of the measuring instrument, that is, the side length error in the arrangement method of the first sphere array 100 and the second sphere array 110, and to evaluate the accuracy. .

  The present invention is not limited to the description of the embodiments and examples of the invention described above. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims.

1 20 Three-dimensional coordinate measuring machine gauge 3, 33 Substrate 40, 140 Sphere array 41 Retainers 43-1 to 43-5, A to E Sphere 50 Auxiliary substrate 7, 23, 51, 53 Column

Claims (8)

A gauge for evaluating the accuracy of a three-dimensional coordinate measuring machine,
A substrate having a flat upper surface, a first sphere array disposed on the upper surface of the substrate,
A three-dimensional coordinate measuring machine gauge, comprising: a second sphere array arranged to be inclined with respect to the upper surface of the substrate.   The said board | substrate consists of a rectangular flat plate, a said 1st spherical body row | line | column is arrange | positioned along one side of the said board | substrate, and a said 2nd spherical body row | line | column is arrange | positioned on a planar view diagonal line in the said board | substrate. Item 1. The gauge according to Item 1.   3. The gauge according to claim 1, wherein a third sphere array is disposed on the upper surface of the substrate so as to be orthogonal to the first sphere array. 4.   4. The gauge according to claim 3, wherein the third sphere row is disposed along another side of the substrate and has a length different from that of the first sphere row.   The gauge according to claim 4, wherein the first sphere row, the second sphere row, and the third sphere row intersect each other and share the first sphere. The first sphere row includes a first sphere A and a second sphere B;
The second sphere row includes the first sphere A and the third sphere E;
The third sphere example includes the first sphere A and the fourth sphere D,
Furthermore, a fourth sphere row comprising the first sphere A and the fifth sphere C is provided, and the fourth sphere row is inclined with respect to the substrate in a direction different from that of the second sphere row. The gauge according to claim 4, wherein The error of the three-dimensional coordinate measuring machine obtained by using the gauge according to any one of claims 1 to 6 is compared with a predetermined length and an allowable error, so that the three-dimensional coordinate measuring machine has an error. An accuracy evaluation method for evaluating accuracy,
(1) fixing the gauge to the three-dimensional coordinate measuring machine, and obtaining a length between spheres included in each sphere row as an output of the three-dimensional coordinate measuring machine;
(2) a calculation step of calculating a first error by comparing the obtained length between spheres with a reference value prepared in advance;
Evaluating the accuracy of the coordinate measuring machine using the error calculated in the calculation step (2);
A method for evaluating the accuracy of a three-dimensional coordinate measuring machine, comprising: The installation posture with respect to the three-dimensional coordinate measuring machine is changed, and step (1) and step (2) according to claim 7 are repeated,
Extracting from the calculated errors first to seventh direction-specific errors having directions corresponding to directions V1 to V7 defined in JIS B 7440;
Evaluating the accuracy of the three-dimensional coordinate measuring machine using the first to seventh direction-specific errors;
A method for evaluating the accuracy of a three-dimensional coordinate measuring machine, comprising: