JP2023017410A - Measuring apparatus and hole position detection method - Google Patents

Abstract

To provide a measuring apparatus and a hole position detecting method capable of detecting a position of a hole in a workpiece.SOLUTION: A measuring apparatus 1 includes: a table 20 on which a workpiece 9 is placed; a stylus 41 that can be displaced in a direction intersecting a hole forming surface 92 of the workpiece 9; a movement control unit that controls a relative movement mechanism so as to scan the hole forming surface 92 in a direction toward the hole 91 with the stylus 41 contacting the hole forming surface 92; a displacement detection unit that detects the displacement of the stylus 41 while the stylus 41 scans the hole forming surface 92; a measuring unit that generates shape data of the hole forming surface 92 based on the displacement of the stylus 41; an edge detection unit that detects edge points corresponding to an edge of the hole 91 from the shape data; an edge coordinate calculation unit that calculates edge coordinates that are coordinates of the edge points with respect to the table 20; and a center coordinate calculation unit that calculates the center coordinates of a virtual circle passing through at least three edge coordinates as the center coordinates of the hole 91.SELECTED DRAWING: Figure 5

Description

The present invention relates to a measuring device and a hole position detection method.

2. Description of the Related Art Measuring devices such as a roundness measuring device, a surface roughness measuring device, or a contour measuring device are conventionally known (see, for example, Patent Document 1). Such a measuring device measures the surface texture of a work by detecting the displacement of a stylus brought into contact with the surface of the work. When measuring the surface properties of the inner surface of a hole formed in a work, the stylus is inserted into the hole of the work and brought into contact with the inner surface of the hole.

JP 2016-065751 A

In the above measuring device, when the exact position of the hole in the work is unknown, the operator visually confirms the position of the hole in the work, thereby preventing the stylus from contacting the work and being damaged.
However, visually confirming the positions of the holes deteriorates the workability of the measurement. In addition, as the diameter of the hole in the work becomes smaller, it becomes more difficult to visually confirm the position of the hole, and there is a risk that the stylus will come into contact with the work and be damaged.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a measuring device and a hole position detection method capable of detecting the position of a hole in a work.

The measuring apparatus of the present invention includes a table on which a work having a surface with a circular hole is placed, a stylus that can be displaced in a direction intersecting the surface of the work, and the stylus that is attached to the table. a relative movement mechanism that moves relative to the work by a relative movement mechanism; a movement control unit that controls the relative movement mechanism so that the stylus contacts the surface of the workpiece and scans the surface in a direction toward the hole; a displacement detector for detecting displacement of the stylus while scanning the surface; a measuring unit for generating shape data of the surface based on the displacement of the stylus detected by the displacement detector; an edge detection unit for detecting edge points corresponding to edges of the hole from data; an edge coordinate calculation unit for calculating edge coordinates that are coordinates of the edge points with respect to the table; and a virtual circle passing through at least three of the edge coordinates. and a center coordinate calculation unit that calculates the center coordinates of the hole as the center coordinates of the hole.

In the present invention, the center coordinates of the holes in the table can be calculated. Therefore, the stylus can be inserted into the hole after being aligned with the center coordinates of the hole, and the stylus can be prevented from coming into contact with the work during insertion. Moreover, since it is not necessary to visually confirm the positions of the holes in the workpiece, the workability of the measurement can be improved.

In the measuring apparatus of the present invention, it is preferable that the edge detection section detects, as the edge point, a point when the shape data is displaced from the scanning start point by a predetermined amount.
According to the present invention, edge points can be easily detected without requiring complicated arithmetic processing. Further, by setting the predetermined amount of displacement to a value larger than the surface roughness of the workpiece, erroneous detection of edge points can be suppressed.

In the measuring apparatus of the present invention, it is preferable that the movement control section further control the relative movement mechanism so that the stylus is inserted into the hole while being aligned with the central coordinates.
In the present invention, the operation of inserting the stylus into the hole of the workpiece is automatically performed, and the workability of measurement can be further improved.

The present invention provides a measuring apparatus comprising a table on which a work is placed and a stylus that can be displaced in a direction intersecting the surface of the work, and which detects the position of a hole formed in the surface of the work. A position detection method comprising: a scanning step in which the stylus contacts the surface of the workpiece and scans the surface in a direction toward the hole; and a displacement detection step in which displacement of the stylus is detected during the scanning step. a measuring step of generating shape data of the surface based on the displacement of the stylus detected in the displacement detecting step; and an edge detecting step of detecting edge points corresponding to edges of the hole from the shape data. and an edge coordinate calculation step of calculating edge coordinates, which are the coordinates of the edge points in the table, and a center coordinate calculation step of calculating the center coordinates of a virtual circle passing through at least three of the edge coordinates as the center coordinates of the hole. And, it is characterized by implementing.
According to the hole position detection method of the present invention, the same effects as those of the above-described measuring device of the present invention can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The side view which shows typically the measuring apparatus which concerns on one Embodiment of this invention. The top view which shows the said measuring apparatus typically. The block diagram which shows the control part of the said measuring apparatus. It is a flowchart which shows the procedure of the hole position detection method in the said measuring device. FIG. 4 is a schematic diagram showing how the stylus of the measuring device scans the hole forming surface of the workpiece; FIG. 4 is a schematic diagram for explaining a method of detecting a hole in a work; FIG. 4 is a schematic diagram showing edge points in shape data; FIG. 4 is a schematic diagram showing examples of a hole forming surface of a work, edge coordinates, and hole center coordinates; FIG. 10 is a schematic diagram for explaining a modification of the method for detecting holes in a work;

〔measuring device〕
1 and 2 are diagrams schematically showing a measuring device 1 according to one embodiment of the present invention.
The measuring device 1 of the present embodiment is a device that contacts a work 9 (object to be measured) to measure the surface properties (for example, shape, roundness, surface roughness, etc.) of the work 9, and includes a base 10 and a base 10, a moving mechanism 30 installed adjacent to the table 20, a detector 40 supported by the moving mechanism 30, and a control unit 50 for controlling the operation of each unit. there is

The table 20 has a cylindrical body 21 rotatably installed on the base 10 and a disk-shaped mounting plate 22 horizontally movably installed on the upper surface of the body 21 . The main body 21 is provided with a motor-driven table rotation mechanism 23 (see FIG. 3), and the main body 21 can be rotated around the rotation axis Cr by the table rotation mechanism 23 . The mounting plate 22 is rotatable together with the main body 21 , and the workpiece 9 to be measured is mounted on the mounting plate 22 . The rotation axis Cr is arranged along the vertical direction.

The table 20 has an operation (centering and leveling) that aligns the rotation axis Cr of the table 20 with the center axis of the work 9 (for example, the center axis of the circle formed by the outer peripheral surface of the work 9 or the center axis of the hole in the work 9). An adjustment mechanism 24 is provided for performing the adjustment. The adjustment mechanism 24 includes a centering mechanism 241 that adjusts the arrangement of the mounting plate 22 with respect to the main body 21 in the CX-axis direction and the CY-axis direction, and an inclination of the mounting plate 22 with respect to the main body 21 in the CX-axis direction and in the CY-axis direction. and a leveling mechanism 242 for adjusting the inclination (see FIG. 2). The centering mechanism 241 and the leveling mechanism 242 are each motor driven.
The CX-axis direction and the CY-axis direction are directions orthogonal to the rotation axis Cr and mutually orthogonal, and form an orthogonal coordinate system (table coordinate system) set for the table 20 .

Further, the table 20 is provided with an angle sensor 25 (see FIG. 3) for detecting the rotation angle θ of the table 20 with respect to the base 10 . The angle sensor 25 is, for example, a rotary encoder, and detects the rotational position of the table 20 with respect to the reference rotational position as the rotational angle θ.

The moving mechanism 30 moves the detector 40 with respect to the base 10 in the X-axis direction, the Y-axis direction, and the Z-axis direction. The moving mechanism 30 constitutes the relative moving mechanism 11 (see FIG. 3) together with the table rotating mechanism 23 and can move the stylus 41 relative to the table 20 .
In this embodiment, the vertical direction is defined as the Z-axis direction, and the direction of approaching and separating from the table 20 on a plane orthogonal to the Z-axis direction is defined as the X-axis direction, which are orthogonal to the Z-axis direction and the X-axis direction. Let the direction be the Y-axis direction. These X-axis direction, Y-axis direction, and Z-axis direction form a three-axis orthogonal coordinate system (base coordinate system) with respect to the base 10 .

Specifically, the moving mechanism 30 includes a column 31 erected on the base 10, a slider 32 provided movably in the Z-axis direction with respect to the column 31, and driving the slider 32 in the Z-axis direction. A Z-axis driving portion (not shown), an arm 33 provided movably in the X-axis direction with respect to the slider 32, an X-axis driving portion (not shown) for driving the arm 33 in the X-axis direction, and the arm 33 A detector supporting portion 34 that is provided movably in the Y-axis direction with respect to and supports the detector 40, and a Y-axis driving portion (not shown) that drives the detector supporting portion 34 in the Y-axis direction. Prepare. The Z-axis driving section, the X-axis driving section, and the Y-axis driving section each include a motor and a ball screw mechanism or rack and pinion mechanism connected to the motor.

Further, the moving mechanism 30 is provided with a position sensor 35 (see FIG. 3) for detecting the position of the detector 40 in the base coordinate system. The position sensor 35 detects, for example, a Z scale that detects the position of the slider 32 in the Z-axis direction, an X scale that detects the position of the arm 33 in the X-axis direction, and a position of the detector support section 34 in the Y-axis direction. It has a Y scale that

Further, the moving mechanism 30 is provided with a turning mechanism (not shown) for changing the attitude of the detector 40 . The turning mechanism changes the attitude of the detector 40 by turning the detector support part 34 around a turning axis Cx provided on the arm 33 along the X-axis direction, for example.

Detector 40 has stylus 41 and displacement detector 42 .
The stylus 41 contacts the surface of the work 9 in the Z-axis direction or the X-axis direction and is displaceable along the surface of the work 9 . In addition, the attitude of the stylus 41 with respect to the displacement detector 42 can be changed according to the contents of measurement.
The displacement detector 42 supports the stylus 41 so as to be displaceable, and detects the displacement of the stylus 41 .

The control unit 50 is configured by a computer, and includes a memory, an arithmetic circuit, and the like. The control unit 50 functions as a movement control unit 51, a measurement unit 52, and a hole position detection unit 53 as shown in FIG.

The movement control unit 51 controls the relative position of the stylus 41 with respect to the workpiece 9 by controlling the movement mechanism 30 or the table rotation mechanism 23 .

The measurement unit 52 can measure the surface properties (for example, shape, roundness, surface roughness, etc.) of the workpiece 9 based on the displacement of the stylus 41 detected by the displacement detection unit 42 .
For example, the measurement unit 52 can measure the surface texture of the workpiece 9 based on the displacement of the stylus 41 detected by the displacement detection unit 42 and the position of the detector 40 detected by the position sensor 35 . Further, the measurement unit 52 can measure the roundness of the workpiece 9 based on the displacement of the stylus 41 detected by the displacement detection unit 42 and the rotation angle θ of the table 20 detected by the angle sensor 25 .

The hole position detector 53 detects the position of the hole when the surface of the work 9 is formed with the hole. The hole position detection section 53 includes an edge detection section 531, an edge coordinate calculation section 532, and a center coordinate calculation section 533, which will be described later.

[How to detect hole position]
The measuring apparatus 1 of this embodiment implements a hole position detection method for detecting the position of the hole when measuring the inner surface of the hole of the work 9 . This hole position detection method will be described with reference to the flowchart of FIG.
Here, as shown in FIG. 5, the hole 91 of the work 9 is opened in a hole forming surface 92, which is a flat surface of the work 9, and the work 9 is centered on an arbitrary central axis Ch. It is formed along Ch. A cross section of the hole 91 intersecting the central axis Ch is circular.

As a preparation before carrying out the hole position detection method of the present embodiment, the workpiece 9 is placed on the table 20 so that the central axis Ch of the hole 91 extends along the Z-axis direction. The center axis Ch of the hole 91 is preferably arranged near the rotation axis Cr, but does not have to coincide with the rotation axis Cr.
Moreover, the diameter of the tip of the stylus 41 used in the measuring device 1 is smaller than the diameter of the cross-sectional shape of the hole 91 . In addition, the detector 40 is adjusted in attitude by a turning mechanism, and arranged to be inclined with respect to the Z-axis direction.

First, the measuring device 1 scans and measures the hole forming surface 92 of the workpiece 9 in one direction (step S1).
Specifically, as shown in FIG. 5, the movement control unit 51 controls the movement mechanism 30 to bring the stylus 41 into contact with an arbitrary scanning start point Ps on the hole forming surface 92 with a predetermined pressure. Thereafter, the movement control unit 51 controls the movement mechanism 30 to move the stylus 41 along the X-axis direction toward the hole 91 to scan the hole forming surface 92 (scanning step). The scanning line from the scanning start point Ps to the hole 91 does not have to pass through the center of the hole 91, and rough positioning is possible.
During scanning of the hole forming surface 92, the displacement detector 42 detects the displacement of the stylus 41 in the Z-axis direction (displacement detection step), and the position sensor 35 detects the position of the detector 40 in the base coordinate system. The measurement unit 52 generates shape data Sm indicating the shape of the hole forming surface 92 of the workpiece 9 based on the detection values input from the displacement detection unit 42 and the position sensor 35 (measurement step).

Here, as shown in FIG. 6, the stylus 41 scanning the hole forming surface 92 is displaced in the Z-axis direction when falling from the hole forming surface 92 into the hole 91 . When the stylus 41 has completely reached the hole 91 , the movement control unit 51 detects that the pressure applied from the workpiece 9 to the stylus 41 has dropped below a predetermined pressure, and finishes scanning the hole forming surface 92 .

Next, as shown in FIG. 7, the edge detection unit 531 detects edge points Pn corresponding to edges of the hole 91 from the shape data Sm generated in step S1 (step S2; edge detection step). Specifically, the edge detection unit 531 detects a data point when the shape data Sm is displaced from the scanning start point Ps by a predetermined amount D as an edge point Pn. Here, the predetermined amount D is an arbitrary displacement amount set in advance, and is set to a value larger than the range including the surface roughness of the hole forming surface 92 so as not to detect the edge point Pn erroneously. is preferred.

Next, the edge coordinate calculator 532 calculates the coordinates (edge coordinates) of the edge point Pn in the table coordinate system (step S3; edge coordinate calculation step).
For example, the edge coordinate calculator 532 acquires the coordinates of the edge point Pn in the base coordinate system from the shape data Sm, and converts the coordinates in the base coordinate system to the rotation angle θ of the table 20 detected by the angle sensor 25 and the base The edge coordinates can be calculated by converting the coordinates of the table coordinate system based on the origin position of the table coordinate system (the position of the rotation axis Cr) in the coordinate system.

Next, the control unit 50 determines whether or not three or more edge coordinates have been calculated (step S4).
When the number of edge coordinates is less than three (step S4; No), the movement control unit 51 controls the table rotation mechanism 23 to rotate the table 20 by an arbitrary angle (for example, 120 degrees). Then, the movement control unit 51 controls the movement mechanism 30 to place the stylus 41 at the same base coordinates as at the start of the previous step S1. As a result, the scanning start point Ps of the hole forming surface 92 in the next step S1 is changed from the scanning starting point Ps of the hole forming surface 92 in the previous step S1 (step S5). That is, the scanning direction is changed from the previous step S1.

After that, steps S1 to S4 described above are performed again. According to such a flow, as shown in FIG. 8, the stylus 41 sequentially scans the hole forming surface 92 of the workpiece 9 along a plurality of different directions toward the hole 91 . As a result, a plurality of edge points Pn (P1 to P3 in FIG. 8) are detected, and the edge coordinates of each edge point Pn are calculated.

When three or more edge coordinates are calculated (step S4; Yes), the central coordinate calculation unit 533 selects arbitrary three edge coordinates (for example, coordinates of edge points P1 to P3). Then, as shown in FIG. 8, the central coordinate calculation unit 533 calculates the central coordinates Ph (CXph, CYph ) is calculated (step S6; central coordinate calculation step). Since this calculation method can use a general circle equation, the details are omitted.
The center coordinates Ph (CXph, CYph) of the virtual circle VC calculated here correspond to the position of the center axis Ch of the hole 91 of the workpiece 9 on the table 20 (the center coordinates of the hole 91). Therefore, the central coordinates of the hole 91 are obtained by the central coordinate calculator 533 calculating the central coordinates of the virtual circle VC.
With the above, the flow of the hole position detection method of the present embodiment ends.

[Insert stylus]
After performing the above-described hole position detection method, the measuring device 1 inserts the stylus 41 into the hole 91, and arbitrary measurements (shape, roundness, surface roughness, etc.) of the inner surface of the hole 91 can be performed. can.

A method of inserting the stylus 41 will be briefly described below.
First, the detector 40 is arranged along the Z-axis direction after its posture is adjusted by the turning mechanism. Thereby, the stylus 41 is arranged along the depth direction of the hole 91 .
The movement control unit 51 also controls the movement mechanism 30 and the table rotation mechanism 23 to align the stylus 41 with the center coordinates of the hole 91 in the table 20 . For example, the movement control unit 51 controls the table rotation mechanism 23 so that the table 20 is positioned at the rotation reference position, and the stylus 41 is arranged at the center coordinates of the hole 91 when the table 20 is at the rotation reference position. It controls the moving mechanism 30 .
After that, the movement control unit 51 controls the movement mechanism 30 to lower the stylus 41 . The stylus 41 is thereby inserted into the hole 91 .

After the stylus 41 is inserted into the hole 91 , the measuring device 1 may perform centering so that the center axis Ch of the hole 91 coincides with the rotation axis Cr of the table 20 . Centering can be performed by a conventional method. Alternatively, the center coordinates of the hole 91 may be used to adjust the adjustment mechanism 24 so that the center coordinates of the hole 91 match the rotation axis Cr of the table 20 .

〔effect〕
In this embodiment, as described above, the center coordinates of the hole 91 in the table 20 can be detected. Therefore, the stylus 41 can be inserted into the hole 91 after being aligned with the center coordinates of the hole 91, and the stylus 41 can be prevented from coming into contact with the workpiece 9 during insertion. Moreover, since it is not necessary to visually confirm the position of the hole 91 of the work 9, the workability of the measurement can be improved.

The edge detection unit 531 of this embodiment detects a data point when the shape data Sm is displaced by a predetermined amount D from the scanning start point Ps as an edge point Pn. According to such a method, the edge point Pn corresponding to the edge of the hole 91 can be easily detected without requiring complicated arithmetic processing. Further, by setting the predetermined amount D of displacement to a value larger than the surface roughness of the workpiece 9, erroneous detection of the edge point Pn can be suppressed.

The movement control unit 51 of this embodiment controls the movement mechanism 30 so that the stylus 41 is inserted into the hole 91 while being aligned with the central coordinates of the hole 91 . As a result, the operation of inserting the stylus 41 into the hole 91 of the workpiece 9 is automatically performed, and the operability of measurement can be further improved.

[Modification]
The present invention is not limited to the above-described embodiments, and includes modifications within the scope of achieving the object of the present invention.

In the above embodiment, the movement control section 51 finishes scanning the hole forming surface 92 when the stylus 41 reaches the hole 91 . As a modification, the movement control unit 51 does not end scanning even when the stylus 41 reaches the hole 91 as shown in FIG. may
In this case, the shape data Sm is displaced in the Z-axis direction at the timing when the stylus 41 falls from the hole forming surface 92 into the hole 91 and the timing when the stylus 41 rides on the hole forming surface 92 from the hole 91 . Based on the shape data Sm, the edge detection unit 531 detects a data point at a point displaced by a predetermined amount D from the scanning start point Ps, and a predetermined amount D after that point to the same Z-axis position as the scanning start point Ps. can be detected as edge points Pn.
According to such a modification, by scanning the hole forming surface 92 of the workpiece 9 in two arbitrary directions, a total of four edge points Pn can be detected.

In the above-described embodiment, the edge detection unit 531 detects as the edge point Pn a point when the shape data Sm is displaced from the scanning start point Ps by a predetermined amount D, but this is the method for detecting the edge point Pn. is not limited to For example, the position of the hole forming surface 92 may be calculated from the shape data Sm, and the edge point Pn may be detected as a point displaced from the calculated position by a predetermined amount.

In the above embodiment, the measuring device 1 functions as a roundness measuring machine. As a modification of this, the measuring device 1 may not function as a roundness measuring machine, and the table 20 may be a direct-acting table that moves in the X-axis direction or the Y-axis direction with respect to the base 10 .
In this case, the movement control unit 51 may move the stylus 41 relative to the work 9 by controlling the movement mechanism of the linear motion table on which the work 9 is placed. That is, the relative movement mechanism of the present invention may include the movement mechanism of the linear motion table.
For example, in step S<b>1 described above, the movement control unit 51 may cause the stylus 41 to scan the hole forming surface 92 of the workpiece 9 by controlling the movement mechanism of the linear motion table. Further, in step S5 described above, the movement control unit 51 may change the scanning start point Ps by controlling the movement mechanism of the linear motion table.
The position of the hole 91 of the workpiece 9 can be detected by such a modified example as well as the above-described embodiment.

Further, in the above-described embodiment, a surface texture measuring machine for measuring the surface texture of the workpiece 9 is exemplified as the measuring device 1, but the present invention is not limited to this. The measuring device of the present invention may be any measuring device having a stylus, such as a three-dimensional measuring device capable of scanning measurement.

DESCRIPTION OF SYMBOLS 1... Measuring apparatus 10... Base 11... Relative moving mechanism 20... Table 21... Main body 22... Mounting plate 23... Table rotating mechanism 24... Adjusting mechanism 241... Centering mechanism 242... Leveling Mechanism 25 Angle sensor 30 Moving mechanism 31 Column 32 Slider 33 Arm 34 Detector support 35 Position sensor 40 Detector 41 Stylus 42 Displacement detector , 50... Control unit 51... Movement control unit 52... Measurement unit 53... Hole position detection unit 531... Edge detection unit 532... Edge coordinate calculation unit 533... Central coordinate calculation unit 9... Work 91... Hole 92... Hole formation surface Ch... Central axis Cr... Rotational axis D... Predetermined amount P1... Edge point P2... Edge point P3... Edge point Pn... Edge point Ps... Scan start point Sm ...shape data, VC...virtual circle, .theta....rotation angle.

Claims (4)

a table on which a workpiece having a surface with circular holes is placed;
a stylus displaceable in a direction intersecting the surface of the workpiece;
a relative movement mechanism for relatively moving the stylus with respect to the table;
a movement control unit that controls the relative movement mechanism so that the stylus contacts the surface of the workpiece and scans the surface in a direction toward the hole;
a displacement detector that detects displacement of the stylus while the stylus scans the surface;
a measurement unit that generates shape data of the surface based on the displacement of the stylus detected by the displacement detection unit;
an edge detection unit that detects an edge point corresponding to the edge of the hole from the shape data;
an edge coordinate calculator that calculates edge coordinates that are coordinates of the edge points with respect to the table;
A measuring device comprising: a central coordinate calculation unit that calculates, as central coordinates of the hole, central coordinates of a virtual circle passing through the at least three edge coordinates. 2. The measuring apparatus according to claim 1, wherein said edge detection unit detects, as said edge point, a point when said shape data is displaced by a predetermined amount from a scanning start point. 3. The measuring device according to claim 1, wherein the movement control section further controls the relative movement mechanism such that the stylus is inserted into the hole while being aligned with the central coordinates. A hole position detecting method for detecting the position of a hole formed in the surface of the work in a measuring device comprising a table on which a work is placed and a stylus that can be displaced in a direction intersecting the surface of the work There is
a scanning step in which the stylus contacts the surface of the workpiece and scans the surface in a direction toward the hole;
a displacement detection step of detecting displacement of the stylus during the scanning step;
a measuring step of generating shape data of the surface based on the displacement of the stylus detected in the displacement detecting step;
an edge detection step of detecting edge points corresponding to edges of the hole from the shape data;
an edge coordinate calculation step of calculating edge coordinates, which are the coordinates of the edge points in the table;
and a center coordinate calculation step of calculating the center coordinates of a virtual circle passing through at least three of the edge coordinates as the center coordinates of the hole.

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