JP2019174273A - Measuring apparatus of board thickness, and measuring method of board thickness - Google Patents

Abstract

An object of the present invention is to measure a thickness and a gap of a machined part with high accuracy even when a workpiece is installed diagonally. In a plate thickness measuring device for measuring the thickness of a work by a pair of sensors which contact a side surface in a thickness direction of the work with a predetermined pressing force, a pair of sensors are provided. And a XY table 20 that moves a pair of sensors 42a and 42b to at least two different measurement points a and b in the longitudinal direction of the workpiece 10. , The thickness C at the measurement point measured by the pair of sensors 42a, 42b, the distance between the two measurement points, and the difference in the measurement direction at the two measurement points a, b by either sensor. To a true thickness. [Selection] Figure 2

Description

  The present invention relates to a plate thickness measuring apparatus and a plate thickness measuring method capable of measuring the thickness of a component machined by a machine tool with high accuracy, and in particular, a blade tool for machining a metal component automatically. The present invention relates to a plate thickness measuring apparatus and a plate thickness measuring method that are incorporated in a machine tool such as a machining center that performs replacement and that measures the thickness of a processed part with high accuracy.

  Machine tools in recent years have adopted a machining center that automatically replaces cutting tools that perform milling, end milling, drilling, boring, tapping, etc., and machining the parts. In order to do this, it is necessary to measure the dimensions of the processed part, for example, the width and the thickness with high accuracy.

  In this patent document 1, a taper shank having the same shape as a taper shank of an exchangeable tool that is selectively attached to a main spindle of a machine tool, and an ultrasonic probe at the tip of the taper shank are attached to the surface of the workpiece W. An ultrasonic plate thickness measuring unit that measures the thickness of the workpiece W by transmitting an ultrasonic wave while detecting contact with the ultrasonic wave and detecting the reflected sound wave, and accurately measuring the thickness of the workpiece such as a thin plate. Sonic plate thickness measuring device technology is described.

  Further, Patent Literature 2 and Patent Literature 3 listed below can be cited as documents that describe a touch probe that measures the outer shape of a processed part in contact with the outer shape of the processed part.

JP-A-2006-75584 JP 2011-136390 A JP 2010-71775 A

  The technique described in Patent Document 1 uses an ultrasonic probe that transmits an ultrasonic wave while contacting the surface of the workpiece and detects the echo to measure the thickness of the workpiece. In order to measure the thickness of the workpiece by measuring the thickness of the workpiece by detecting the reflected sound wave, it is necessary to use a contact medium that improves the contact state between the ultrasonic probe and the workpiece surface when measuring the thickness. There is a problem that the thickness (also referred to as width) which is the dimension in the plane direction of the workpiece mounted on the substrate cannot be measured.

  In addition, the technique described in Patent Document 2 is limited to the effect of measuring the outer shape of a processed part using one touch probe, and the technique described in Patent Document 3 includes two touch probe contacts. The effect is that the position can be corrected and confirmed at the same time by pressing and abutting on the piece almost simultaneously.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a plate thickness measuring apparatus that can be incorporated in a machine tool and can measure the thickness and gap of processed parts with high accuracy. An object of the present invention is to provide a method for measuring a plate thickness, and in particular, to measure the thickness and gap of a processed part with high accuracy even when a workpiece is installed obliquely.

  The present invention that achieves the above object provides a plate thickness measuring device that measures the thickness of the workpiece by a pair of sensors that face and contact the side surfaces in the thickness direction of the workpiece with a predetermined pressing force. A measuring device that moves in the vertical direction and the thickness direction that is the measurement direction, and an XY table that moves the pair of sensors to at least two measurement points that are different in the longitudinal direction of the workpiece, are measured by the pair of sensors. The true thickness is obtained based on the thickness at the measurement point, the distance between the two measurement points, and the difference in the measurement direction at the two measurement points by any one of the sensors.

  In the above description, the thickness at the measurement point is C, the distance between the two measurement points is ba, and the difference in the measurement direction at the two measurement points by any one of the sensors is the push amount S. , Θ = tan −1 (S / b−a) is obtained, and it is desirable to set the true thickness t = C · (cos θ).

  Furthermore, in the above, it is desirable that the approximate thickness serving as the measurement standard of the workpiece is 5 to 15 mm, and the distance between the two measurement points is 5 to 15 mm.

  Furthermore, in the above, instead of moving the pair of sensors to at least two measurement points different in the longitudinal direction of the workpiece on the XY table, two sets of the pair of sensors are disposed in the longitudinal direction on the measuring device. It is desirable to fix at a predetermined interval and set the predetermined interval as the distance between the two measurement points.

Furthermore, in the above, let r be the radius of the contact of the pair of sensors that contacts the workpiece, the measured value D measured by the pair of sensors, and the error due to misalignment due to the difference in the contact position of the contact, x, The thickness at the measurement point is C, the distance between the two measurement points is ba, and the difference in the measurement direction at the two measurement points by any one of the sensors is an indentation amount S.
θ = tan−1 (S / ba),
x = r · ((1 / cos θ) −1),
C = D−2 · x,
It is desirable that the true thickness be t = C · (cos θ).

  Furthermore, in the above, it is desirable that the approximate thickness as a measurement standard of the workpiece is 5 to 15 mm, the distance between the two measurement points is 5 to 15 mm, and the radius r of the contact is 4 to 8 mm.

  Further, in the above, instead of moving the pair of sensors to at least two measurement points different in the longitudinal direction of the workpiece on the XY table, the pair of measurement points is set to at least two measurement points different in the vertical direction. It is desirable to move this sensor.

  Further, the present invention is a plate thickness measuring method for measuring the thickness of the workpiece by a pair of sensors that face and contact the side surface in the thickness direction of the workpiece with a predetermined pressing force, in the longitudinal direction of the workpiece. The pair of sensors are moved to at least two different measurement points, the thickness at the measurement point measured by the pair of sensors, the distance between the two measurement points, and the two measurement points by any one of the sensors. The true thickness is based on the difference in the measurement direction.

  The plate thickness measuring apparatus and the plate thickness measuring method according to the present invention can measure the thickness and gaps of processed parts with high accuracy even when the workpiece to be measured is installed obliquely.

The figure for demonstrating the whole structure and operation | movement of the plate | board thickness measuring apparatus by the Example of this invention. The top view which shows the measurement part of the plate | board thickness measuring apparatus by the Example of this invention The top view which shows the detail of the measurement part by a present Example The top view which shows the plate | board thickness measuring apparatus which is another Example Furthermore, the side view which shows the measuring apparatus of the plate thickness which is another Example

  Hereinafter, an embodiment of a machine tool provided with a thickness measuring unit to which a thickness measuring method according to the present invention is applied will be described.

[Constitution]
The machine tool 100 to which the thickness measuring unit according to the present embodiment is applied, as shown in FIG. 1A, for example, with respect to a plate-shaped workpiece 10 mounted on an XY table 20 operating in the XY plane direction. A tool 30 for automatically exchanging cutter tools for milling, end milling, drilling, boring, tapping, etc., and machining the parts, and checking the machining accuracy in the workpiece machining process in the machining unit 30 And a measuring device 40 that measures the thickness t in the plane direction (X direction) with high accuracy. In the present embodiment, the work 10 has a rectangular flat plate shape, and is mounted free so that the four side surfaces are parallel to the XY axes of the XY table 20, but may be fixed.

  The measuring apparatus 40 according to the present embodiment faces two arms 41 that are movable vertically and vertically in the measurement direction (thickness t direction in this example) toward the plane of the XY table 20 and the lower end of the arm 41. The sensor 42a and the sensor 42b that are arranged in contact with each other at a predetermined pressure from the X direction on the side surface of the workpiece 10 to be measured, and the thickness t of the workpiece 10 is detected by optically detecting the positions of the sensors 42a and 42b. An optical measurement unit (not shown) for measurement. Further, the sensors 42a and 42b according to the present embodiment have contacts which are contactors facing each other and whose outer shape is a hemispherical contact, and the hemispherical contacts are in contact with the parallel side surface of the workpiece 10 to be measured with a predetermined pressure. It is an optical type that optically detects the position of the contact by being pressed by the contact, but it may be a differential transformer type that electrically detects a change in the amount of insertion of the core inserted into the coil.

  In the machine tool 100 according to the present embodiment, the machining unit 30 performs cutting and the like while automatically exchanging the blade tool with respect to the workpiece 10, and the machining dimension of the workpiece 10 during the machining step is a predetermined value. The workpiece 10 is configured to be processed while repeating the measurement step of measuring by the measuring device 40 whether or not the range (several μm to several tens μm).

The measurement process according to the present embodiment is as follows.
(1) From the state where the working unit 30 and the measuring device 40 are positioned on the work 10 mounted on the XY table 20 shown in FIG. 1B, the work 10 is placed on the work 10 as shown in FIG. A first step of lowering the working unit 30 and the measuring device 40 to a position where the sensors 42a and 42b arranged facing the lower ends of the pair of arms 41 extending from the measuring device 40 face both side surfaces of the workpiece 10. In this example, an example in which the machine part 30 and the measuring device 40 are simultaneously moved up and down will be described. However, the machine part 30 is fixed at the upper position and only the measuring device 40 is moved up and down, or the machine part 30 and the measuring device. 40 may be configured to move up and down in the Z-axis (gravity) direction.

  (2) Next, as shown in FIGS. 1D to 1E, the sensors 42a and 42b of the pair of arms 41 are brought closer to the side surface in the thickness direction of the work 10 on the XY table 20, and the work 10 A second step of moving so as to be in contact with a side surface in the thickness direction (for example, a measurement point a shown in FIG. 2A) with a predetermined pressure.

  (3) A third step of measuring the position coordinate values of the sensor 42a and the sensor 42b in contact with both sides of the workpiece 10 at the measurement point a of the workpiece 10 shown in FIG.

  (4) Next, the sensors 42a and 42b that are in contact with both sides of the workpiece 10 are moved away from both sides of the workpiece 10 in the opposite direction to the second step, and the arrow direction (Y) shown in FIG. The sensor 42a and the sensor 42b of the pair of arms 41 are moved in the direction (longitudinal direction), and the sensor 42a and the sensor 42b of the pair of arms 41 are approached again toward the side surface in the thickness direction of the workpiece 10 to increase the thickness of the workpiece 10. A fourth step of moving so as to be in contact with a lateral surface (for example, the measurement point b shown in FIG. 2A) at a predetermined pressure; Or it moves to the measurement point b as it is, without moving in the opposite direction to the second step.

  The measuring apparatus 40 according to the present embodiment measures the position coordinate values at the measurement points a and b of the pair of sensors 42a and 42b that are in contact with both side surfaces of the workpiece 10 with a predetermined pressure in this way. The true thickness t of the workpiece 10 is calculated from the value. That is, the thickness based on the difference between the position coordinate values of the sensor 42a and the sensor 42b at the measurement point a and the thickness based on the difference between the position coordinate values of the sensor 42a and the sensor 42b at the measurement point b are measured.

  In measuring the thickness of the workpiece 10 at the measurement point ab, when the four side surfaces of the workpiece 10 are completely coincident with the XY direction of the XY table 20, the measurement values at both measurement points are logically the same. In the actual machine, the four side surfaces of the workpiece 10 do not always coincide with the Y direction of the XY table 20 in micron units, and it is assumed that the workpiece 10 is mounted obliquely as shown in FIG. The When the workpiece 10 is mounted obliquely, the contacts of the pair of contacts of the sensor that moves simultaneously contact each other at the coaxial position in the Y direction of the XY table 20 (see FIG. 2A), and the thickness C at this measurement point Is different from the true thickness t by the inclination of the workpiece 10.

  Therefore, in this embodiment, in order to deal with the fact that the workpiece 10 is arranged obliquely, correction for the workpiece oblique arrangement described below is performed, and this correction calculation method will be described below.

  First, when the above-described workpiece 10 is disposed obliquely by an angle θ, the thicknesses measured at the measurement points a and b are relative to the true thickness t of the workpiece 10 as shown in FIG. Thus, an error due to inclination occurs, and the thickness C at the measurement point becomes a measurement value.

  The positional relationship between the thickness C at the measurement point, the true thickness t, and each sensor is expressed as shown in FIG. 3, and the inclination angle θ, the true thickness t, and the X position of the sensor 42b at the measurement point a. When the pressing amount S of the sensor 42b at the reference measurement point b in the X direction (difference in position in the measurement direction between the measurement point a and the measurement point b by any sensor) and the thickness C at the measurement point , True thickness t = C · (cos θ). However, θ = tan−1 (S / ba), ba is the distance from the measurement point a to the measurement point b.

That is, the true thickness t is obtained by measuring the thickness C of the workpiece 10 at least at two different measurement points, measurement point a and measurement point b, with a pair of sensors 42a and 42b, and measuring thickness C at the measurement point. What is necessary is just to correct | amend based on the distance (distance between two measurement points a and b) from the point a to the measurement point b, and the pushing amount S. When the error δ is (C−t), δ = C (1−cos θ). Table 1 shows an example in which the inclination angle θ is calculated by setting the distance ba from the measurement point a to the measurement point b to 10 mm and the true thickness t to 10 mm = 10000 μm.

  If the distance ba from the measurement point a to the measurement point b is increased, the inclination angle θ can be calculated more accurately. However, since the distance in the Y direction that moves from the measurement point a to the measurement point b is increased, the influence of errors such as linearity in the moved XY table 20 increases. Therefore, it is preferable to appropriately determine the distance ba from the measurement point a to the measurement point b depending on the thickness of the workpiece 10.

  For example, it is preferable that the approximate thickness of the workpiece 10 serving as a measurement standard and the distance ba are substantially equal. Table 1 shows the case where the approximate thickness of the workpiece 10 is 10 mm and the distance ba is 10 mm. As a result of actual measurement under these conditions, if the tolerance required for the workpiece 10 is 10 μm, the inclination angle θ is It was found that the correction is effective up to 3 ° and up to at least 10 °. Further, when the thickness of the workpiece 10 to be measured was 5 to 15 mm, it was appropriate that the distance ba was 5 to 15 mm.

Table 2 is an example in which the indentation amount S was calculated under the same conditions as in Table 1, with the distance ba from the measurement point a to the measurement point b being 10 mm and the true thickness t being 10 mm.

  To detect a small inclination angle θ, the larger the distance ba, the better. However, the XY table 20 needs to be highly accurate. In response to this, the two sensors 42a and 42b are changed to four points, the measurement points a and b are measured by two sensors, and the distance ba is fixed on the sensor side and fixed. And

  That is, instead of moving the pair of sensors 42a and 42b to at least two measurement points different in the longitudinal direction of the workpiece 10 on the XY table 20, two pairs of sensors 42a and 42b are moved in the longitudinal direction on the measuring device 40. The predetermined interval is fixed, and this predetermined interval is defined as the distance between the two measurement points a and b. As a result, the distance ba can be made independent of the movement of the XY table 20 and contributes to higher accuracy. In addition, since measurement can be performed simultaneously without moving from measurement point a to measurement point b, the measurement time is shortened.

  FIG. 3 is a plan view showing details of the measurement unit, and considers the influence when the radius r of the contact is used. In actual measurement, since the contacts of the sensors 42a and 42b have a finite radius r, the position of the contact point with the workpiece 10 in the X direction is displaced. As shown in FIG. 3, as the measurement value D measured by the sensors 42a and 42b, the thickness C at the measurement point is C = D−2 · x, where x is the error due to the displacement due to the difference in the contact position of the contact. . Further, x is x = r · ((1 / cos θ) −1).

  Therefore, if the radius r of the contact is known, an error x due to misregistration is obtained as θ = tan−1 (S / ba), and the measurement point is obtained from the measurement value D as described above and C = D−2 · x. The true thickness t = C · (cos θ) can be obtained by obtaining the thickness C at.

Table 3 shows the error x caused by the displacement and the total error 2x for each inclination angle θ with the contact radius r of 6000 μm (mm).

  Compared to Table 1, for example, the inclination angle θ is 3 ° and the error is 13.723 μm from Table 1, whereas in Table 3, the total error is 16.4682 μm, which is sufficiently small. However, it can be seen that when the inclination angle θ increases, the value cannot be ignored. Further, if the contact radius r is large, the error cannot be ignored. However, when the thickness of the workpiece 10 to be measured is 5 to 15 mm and the distance ba is 5 to 15 mm, the contact radius r is 4 to 8 mm. It was appropriate to do.

  FIG. 4 is a plan view showing another embodiment, and in comparison with the embodiment shown in FIG. 2, the measurement points are set to three points of measurement points a, b, and c in the Y direction. is there. Similar to the description of FIGS. 2 and 3, at the measurement point a and the measurement point b, the true thickness t = C · (cos θ) and θ = tan −1 (S / L) can be obtained. C is the thickness C at the measurement point, and L is the distance ba from the measurement point a to the measurement point b.

  In addition, at the measurement point b and the measurement point c, the true thickness t can be similarly obtained if L in the above equation is the distance cb from the measurement point b to the measurement point c. Further, at measurement point a and measurement point c, if L is a distance c-a from measurement point a to measurement point c, true thickness t can be obtained in the same manner. Average the true thickness obtained at measurement point a and measurement point b, the true thickness obtained at measurement point b and measurement point c, and the true thickness obtained at measurement point a and measurement point c. In this case, a more accurate value is calculated. Hereinafter, the true thickness t can be similarly calculated when the number of measurement points is three or more.

  In addition, when the measurement point is three points of measurement point a, measurement point b, and measurement point c, if the workpiece 10 has a constant thickness, the total amount of pushing by the sensor 42a and the sensor 42b at each measurement point Alternatively, the difference between the position coordinate values of the sensor 42a and the sensor 42b is the same. Therefore, the parallelism in the Y direction of the workpiece 10 and the machining accuracy can be detected from the total value of the push-in amount at each measurement point or the shift amount of the difference between the position coordinate values.

  FIG. 5 is a side view showing still another embodiment, in which the measurement points are set to the measurement point f and the measurement point g in the Z direction as compared with the other embodiments shown in FIG. Similar to the description of FIGS. 2 and 3, at the measurement point f and the measurement point g, the true thickness t = C · (cos θ) and θ = tan −1 (S / f−g) can be obtained. C is the thickness C at the measurement point, and f−g is the distance in the Z direction from the measurement point f to the measurement point g.

  Also in this case, as in FIG. 4, the total value of the push-in amounts by the sensors 42a and 42b or the difference between the position coordinate values of the sensors 42a and 42b is the same at each measurement point. Therefore, the parallelism in the Z direction of the workpiece 10 and the machining accuracy can be detected from the total value of the push-in amount at each measurement point or the shift amount of the difference between the position coordinate values.

  Note that the workpiece 10 that is the measurement target of the present example is a parallelogram shape parallel to the XY direction, but it has been found that only the Y direction has a trapezoidal shape that is inclined. However, the error due to the angle of the work trapezoidal shape may be corrected.

  In the above-described embodiment, the example in which the contact is in contact with the side surface of the workpiece having parallel side surfaces is measured. However, for example, a pair of contacts are inserted into the boring or polished interval, By widening the gap, it is possible to accurately measure the thickness (gap) of the gap formed by boring or the like. In addition, the contact according to the present embodiment has been described as having a semicircular shape protruding inwardly from the tip of the arm, but like a general touch probe, a spherical contact provided on the tip of the arm on a fine line. It may be a child.

C thickness at measurement point, t true thickness, S push-in amount, r contact radius, D measured value, 10 workpieces, 20 XY table, 30 working part, 40 measuring device,
41 Arm, 42a Sensor A, 42b Sensor B, 100 Machine tool

Claims (9)

In the plate thickness measuring device that measures the thickness of the workpiece by a pair of sensors that face and contact the side surface in the thickness direction of the workpiece with a predetermined pressing force,
A measuring device that moves the pair of sensors in the thickness direction which is the vertical direction and the measuring direction;
An XY table for moving the pair of sensors to at least two measurement points different in the longitudinal direction of the workpiece;
Based on the thickness at the measurement point measured by the pair of sensors, the distance between the two measurement points, and the difference in the measurement direction at the two measurement points by any one of the sensors. An apparatus for measuring a plate thickness, characterized in that The thickness at the measurement point is C, the distance between the two measurement points is ba, and the difference in the measurement direction at the two measurement points by any one of the sensors is an indentation amount S.
2. The plate thickness measuring apparatus according to claim 1, wherein θ = tan −1 (S / b−a) is obtained and the true thickness t = C · (cos θ) is obtained.   The thickness measuring apparatus according to claim 1 or 2, wherein an approximate thickness serving as a measurement standard of the workpiece is 5 to 15 mm, and a distance between the two measurement points is 5 to 15 mm.   Instead of moving the pair of sensors to at least two measurement points that are different in the longitudinal direction of the workpiece on the XY table, two pairs of the sensors are fixed to the measuring device at predetermined intervals in the longitudinal direction. 4. The plate thickness measuring apparatus according to claim 1, wherein the predetermined interval is a distance between the two measuring points. The radius of the contact of the pair of sensors that contacts the workpiece is r, the measured value D measured by the pair of sensors, the error due to misalignment due to the difference in the contact position of the contact, and the thickness at the measurement point. C is the distance between the two measurement points, b−a, and the difference in the measurement direction at the two measurement points by any one of the sensors is defined as an indentation amount S.
θ = tan−1 (S / ba),
x = r · ((1 / cos θ) −1),
C = D−2 · x,
The thickness measuring apparatus according to claim 1, wherein the true thickness is t = C · (cos θ).   The approximate thickness as a measurement standard of the workpiece is 5 to 15 mm, the distance between the two measurement points is 5 to 15 mm, and the radius r of the contact is 4 to 8 mm. Thickness measuring device.   The thickness measuring device according to any one of claims 1 to 6, wherein the number of measurement points is three or more in the longitudinal direction.   Instead of moving the pair of sensors to at least two measurement points that are different in the longitudinal direction of the workpiece on the XY table, the pair of sensors is moved with the measurement points being at least two measurement points that are different in the vertical direction. The thickness measuring apparatus according to any one of claims 1 to 6, wherein: A plate thickness measuring method for measuring the thickness of the workpiece by a pair of sensors facing and contacting the side surface in the thickness direction of the workpiece with a predetermined pressing force,
The pair of sensors are moved to at least two measurement points different in the longitudinal direction of the workpiece, the thickness at the measurement point measured by the pair of sensors, the distance between the two measurement points, and any of the sensors The thickness is measured based on the difference in the measurement direction at the two measurement points according to the above.