Measurement apparatus, measurement method, and measurement control program

Abstract

To provide a measuring device, a measuring method, and a measurement control program capable of suppressing the influence of an error caused by numerical calculation for temperature correction.SOLUTION: A measurement device (1) includes a detector (10) for measuring an object to be measured, a temperature sensor (80) for measuring a temperature of the object to be measured at the time of measurement, and a control unit (102) that converts a measurement result obtained by the detector into a temperature correction coordinate system having a measurement start point of the object to be measured as an origin and applies temperature correction based on the temperature at the time of measurement to the measurement result converted into the temperature correction coordinate system.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a measuring device, a measuring method, and a measurement control program, and more particularly to a measuring device, a measuring method, and a measurement control program for measuring the shape, roughness, contour, etc. of the surface of an object to be measured. [Background technology]

[0002] Measuring devices are known for measuring the shape, roughness, contour, etc. of the surface of a measurement object (workpiece). Such measuring devices are equipped with a mechanism whose parameters change with temperature (for example, thermal expansion). Furthermore, the parameters of the measurement object may also change with temperature. If the parameters of the measuring device or the measurement object change with temperature, the measurement results of the measurement object will fluctuate.

[0003] Furthermore, in relation to the measuring equipment mentioned above, the Japanese Industrial Standard JIS B0680: 2007 (ISO1: 2002) stipulates that the standard temperature used for specifying and verifying the geometric characteristics of products shall be 20°C (JIS: Japanese Industrial Standards, ISO: International Organization for Standardization).

[0004] A shape measuring device has been proposed that uses a temperature sensor to detect the temperature of an object during measurement and corrects the driving program or measurement results of the measuring device. For example, Patent Document 1 discloses that temperature sensor detection units are attached to each component of a coordinate measuring machine and to the object to be measured, and that temperature data acquired by the temperature sensors is used to perform temperature correction processing on the actual dimensions of the object to be measured or the measurement operation of the coordinate measuring machine (changing the stop position of each driving unit during the measurement operation). In Patent Document 1, the above-mentioned temperature correction processing makes it possible to obtain the dimensions of the object to be measured at a standard temperature (20°C). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-090427 Summary of the Invention [Problem to be solved by the invention]

[0006] When performing temperature correction on measurement results such as the actual dimensions of an object, the actual dimensions of the object at standard temperature are determined by performing numerical calculations using, for example, the temperature measurement results from a temperature sensor and the actual dimensions of the object. Numerical calculations using a computer can sometimes result in errors due to the nature of the computer. If such errors are introduced into the numerical calculations for temperature correction, the accuracy of the temperature correction of the actual dimensions of the object will decrease, and the measurement accuracy of the measuring device will also decrease.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a measurement device, a measurement method, and a measurement control program that can suppress the influence of errors caused by numerical calculations for temperature correction. [Means for solving the problem]

[0008] A measurement device according to a first aspect of the present invention comprises a detector for measuring an object to be measured, a temperature sensor for measuring the temperature of the object to be measured at the time of measurement, and a control unit that converts the measurement results from the detector into a temperature correction coordinate system whose origin is the measurement start point of the object to be measured, and applies temperature correction based on the temperature at the time of measurement to the measurement results converted into the temperature correction coordinate system.

[0009] In the measurement device according to the second aspect of the present invention, in the first aspect, the control unit converts the measurement results into a coordinate system for temperature correction by translating the measurement starting point of the object to be measured in the measurement results measured based on a coordinate system for outputting measurement results to the origin.

[0010] A measurement device according to a third aspect of the present invention is the first or second aspect, wherein the control unit converts the measurement result after applying temperature correction into a coordinate system for outputting measurement results and outputs the converted result.

[0011] A measurement method according to a fourth aspect of the present invention comprises the steps of converting the measurement results of the object to be measured into a temperature correction coordinate system whose origin is the measurement start point of the object to be measured, and applying temperature correction based on the temperature at the time of measurement to the measurement results converted into the temperature correction coordinate system.

[0012] A measurement control program according to a fifth aspect of the present invention causes a computer to realize the functions of converting the measurement results of an object to be measured into a temperature correction coordinate system whose origin is the measurement start point of the object to be measured, and applying temperature correction based on the temperature at the time of measurement to the measurement results converted into the temperature correction coordinate system. [Effects of the Invention]

[0013] According to the present invention, by using a coordinate system for temperature correction, it is possible to suppress the influence of errors caused by numerical calculations for temperature correction. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing a measurement device according to an embodiment of the present invention; [Figure 2] 2 is a block diagram showing a control device of the measurement device according to the embodiment of the present invention; FIG. [Figure 3] 10A and 10B are diagrams showing measurement results before and after application of temperature correction in a workpiece coordinate system. [Figure 4] FIG. 10 is a diagram showing measurement results before and after application of temperature correction using a temperature correction coordinate system. [Figure 5] FIG. 10 is a diagram showing an example in which temperature correction is applied to the measurement results of the contour of a rectangular parallelepiped measurement object. [Figure 6] FIG. 10 is a diagram showing an example in which temperature correction is applied to the measurement results of the contour of a hemispherical measurement object. [Figure 7]1 is a flowchart showing a measurement method (temperature correction method) according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] [Measuring equipment] 1 is a diagram showing a measurement device according to one embodiment of the present invention. In the following description, a three-dimensional Cartesian coordinate system is used in which the XY plane is the horizontal plane and the Z direction is the vertical direction (perpendicular direction).

[0017] The measuring device 1 is a device for measuring the shape, roughness, contour, etc. of the surface of a measuring object W placed on a measuring object placement section (hereinafter referred to as a stage) 50.

[0018] 1, the stage 50 is placed on a base 52, and the surface of the stage 50 (the surface on which the measurement target W is placed) is parallel to the XY plane. A column (Z axis) 54 extending approximately perpendicular to the surface of the stage 50 is placed on the base 52. A carriage (X axis) 56 is attached to the column 54, and the carriage 56 is movable in the Z direction along the column 54 by an actuator (not shown).

[0019] The detector 10 is attached to the carriage 56, and the detector 10 is movable in the X direction relative to the carriage 56 by an actuator (not shown). A scale 58 for detecting the X direction position of the detector 10 is attached to the carriage 56. The scale 58 is, for example, a linear scale (linear position scale) with scale graduations formed along its length.

[0020] In this embodiment, the detector 10 is movable relative to the column 54, but the present invention is not limited to this. For example, the column 54 may be movable along the X direction relative to the stage 50, or the stage 50 may be movable along the X or Z direction relative to the column 54. That is, it is sufficient that the measurement object W placed on the stage 50 and the detector 10 are configured to be relatively movable in the X and Z directions. Furthermore, the detector 10 may be configured to be relatively movable not only in the X direction but also in the Y direction relative to the measurement object W placed on the stage 50.

[0021] As shown in FIG. 1, the detector 10 includes a stylus portion 14, an arm portion 16, a swing shaft 20, a scale 22, and a scale head 24.

[0022] The stylus unit 14 is fixed to the arm unit 16 so as to extend in the X direction. Hereinafter, the stylus unit 14 attached to the arm unit 16 will be referred to as the swing unit 18. The swing unit 18 is attached to the detector housing 26 so as to be swingable integrally around a swing shaft 20. The mounting angle of the detector 10 relative to the carriage 56 is adjusted so that the swing shaft 20 is approximately parallel to the XY plane.

[0023] The configuration of the swinging part 18 is not limited to the example shown in Fig. 1. For example, the stylus part 14 or the arm part 16 may have an L-shaped bent part, and the stylus part 14 and the arm part 16 may be attached so as to be approximately parallel to each other.

[0024] A stylus 12 is provided at the tip of the stylus unit 14. The stylus 12 extends downward (in the -Z direction) in the figure. When the stylus 12 is brought into contact with the surface of the measurement object W placed on the stage 50 with a predetermined pressure, the oscillating unit 18 oscillates around the oscillating axis 20 according to the height and unevenness of the surface of the measurement object W at the contact position.

[0025] The configuration of the stylus unit 14 is not limited to the example shown in Fig. 1. For example, the stylus unit 14 may be a T-shaped stylus with styluses provided in the vertical direction in the figure, or an L-shaped stylus with a stylus that protrudes downward in the figure longer than in the example shown in Fig. 1.

[0026] The scale 22 is fixed to the detector housing 26 so as to face the base end of the arm portion 16. The detector housing 26 is a member that connects the oscillation center 20C of the oscillation shaft 20 and the scale 22 (that defines the distance between the oscillation center 20C of the oscillation shaft 20 and the scale 22).

[0027] The scale 22 is, for example, a linear scale (linear position scale), and scale graduations are formed along the length direction of the scale 22. The scale 22 is attached so that its length direction (displacement detection direction) is approximately perpendicular to the length direction of the oscillating part 18.

[0028] The scale head 24 is fixed to the base end of the arm portion 16 and is capable of swinging integrally with the swinging portion 18. The scale head 24 is a device that reads the graduations of the scale 22 fixed to the detector housing 26 at an opposing position. The scale head 24 may be, for example, a photoelectric sensor for reading the graduations of the scale 22 or a non-contact sensor that includes an imaging element and an illumination light source (for example, an LED (Light-Emitting Diode)).

[0029] The reading of the graduations of the scale 22 read by the scale head 24 is output to the control unit 102 of the control device 100 provided in the measuring device 1 (see FIG. 2).

[0030] The control unit 102 controls the actuators provided on the column 54 and carriage 56 to move the measurement object W and the stylus 12 of the detector 10 relative to each other, while acquiring the readings of the graduations on the scale 22 for each position on the surface of the measurement object W. This makes it possible to measure the shape, roughness, contour, etc. of the surface of the measurement object W.

[0031] In this embodiment, the scale 22 is fixed to the detector housing 26, and the scale head 24 is fixed to the base end of the arm section 16, but the present invention is not limited to this. For example, the scale head 24 may be fixed to the detector housing 26, and the scale 22 may be fixed to the base end of the arm section 16. Furthermore, the scale 22 is not limited to a linear scale, and may be, for example, an arc scale (angle scale) formed in an arc shape along the swing direction of the arm section 16.

[0032] The temperature sensor 80 is a temperature sensor capable of measuring the temperature of a predetermined location in the measurement device 1. In the example shown in FIG. 1, one temperature sensor 80 is disposed near the stage 50 on which the measurement object W is placed, but the number and installation locations of the temperature sensors 80 are not particularly limited. For example, a temperature sensor may also be disposed near the scale 22 inside the detector housing 26, near the scale 58 on the carriage 56, etc. Note that the temperature sensor 80 may be, for example, a radiation temperature sensor or a color temperature sensor.

[0033] The control unit 102 of the control device 100 controls each unit of the measurement device 1 to measure the measurement object W. When measuring the measurement object W, the control unit 102 receives temperature data D detected by the temperature sensor 80. 80 and obtain the temperature data D 80 The measurement results are corrected (temperature correction) based on the temperature of the measurement object W, the scale 22, and the scale 58. Note that the temperature correction is not limited to the correction of the measurement results. For example, the drive control and position control of the detector 10, etc. may be performed based on the temperatures of the measurement object W, the scale 22, and the scale 58.

[0034] 2 is a block diagram showing the control device 100 of the measurement device 1. As shown in FIG. 2, the control device 100 includes a control unit 102, an input unit 104, a display unit 106, and a storage 108.

[0035] The control unit 102 includes a processor (e.g., a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit)) for controlling each part of the measuring device 1, and memory (e.g., a ROM (Read Only Memory), a RAM (Random Access Memory)). In response to an operation input from the input unit 104, the control unit 102 outputs control signals for controlling the control device 100 and the measuring device 1, and control signals for controlling an actuator for moving the detector 10, etc. The control unit 102 also has a measurement control function and a temperature correction function.

[0036] The control unit 102 has a function of detecting the type of the measurement unit when a part of the components (measurement unit) of the measurement device 1, such as the stylus unit 14 or the detector 10, is replaced, and a function of correcting temperature based on the type of the measurement unit and the temperatures at the time of calibration and measurement. The control unit 102 is an example of a computer.

[0037] The input unit 104 is a device for receiving operation input from an operator, and includes, for example, a keyboard, a mouse, a touch panel, and the like.

[0038] The display unit 106 is a device for displaying images and includes, for example, an LCD (Liquid Crystal Display). The display unit 106 displays, for example, a GUI (Graphical User Interface) for operating the control device 100, the measuring device 1, the actuator, etc., and measurement results such as the shape, roughness, or contour of the surface of the measurement target W.

[0039] The storage 108 is a device for storing programs for controlling the measurement device 1 and data of measurement results, and includes, for example, a hard disk drive (HDD) or a solid state drive (SSD). 80may be stored in the storage 108. The storage 108 stores a measurement control program for causing the control unit 102 to realize the measurement control function and the temperature correction function.

[0040] The detector drive mechanism 60X includes an X-axis drive unit (for example, an actuator, not shown in FIG. 1) for moving the detector 10 in the X direction relative to the carriage 56.

[0041] The detector drive mechanism 60Z includes a Z-axis drive unit (for example, an actuator, not shown in FIG. 1) for moving the carriage 56 in the Z direction relative to the column 54, thereby moving the detector 10 in the Z direction.

[0042] The temperature sensor 80 is a temperature sensor capable of measuring the environmental temperature near the stage 50. In the example shown in FIG. 1, the temperature sensor 80 is disposed near the stage 50, but the installation location of the temperature sensor 80 is not particularly limited. For example, instead of the environmental temperature measured by the temperature sensor 80, it is also possible to use the temperature of a drive unit such as the detector drive mechanism 60X or 60Z. Note that the temperature sensor 80 may be, for example, a radiation temperature sensor or a color temperature sensor for measuring the temperature of the measurement object W, the calibrator, or the detector 10.

[0043] When the stylus 12 comes into contact with the surface of the measurement object W during measurement, the swinging unit 18 (arm unit 16) is displaced in the Z direction. The control unit 102 receives an input of a reading (scale head detection value) of the scale 22 by the scale head 24. The control unit 102 also receives an input of a reading (scale detection value) of the scale 58 indicating the amount of movement of the detector 10 in the X direction. The control unit 102 then uses the scale head detection value and the scale detection value to perform calculations on the shape, roughness, contour, etc. of the surface of the measurement object W. The control unit 102 also receives temperature data D detected by the temperature sensor 80. 80 is obtained and temperature correction is performed.

[0044] 2, the control unit 102 of the control device 100 having the measurement control function also has the temperature correction function, but the present invention is not limited to this. The temperature correction function may be provided in a device separate from the control device 100.

[0045] [Temperature correction processing] The measuring device 1 has two coordinate axes: a machine coordinate system and a workpiece coordinate system.

[0046] The mechanical coordinate system is a coordinate system specific to the measuring device 1, and is, for example, an orthogonal coordinate system defined based on a mechanical origin determined by the manufacturer of the measuring device 1. Here, the mechanical origin is set within the range measurable by the measuring device 1 (i.e., the movable range of the stylus 12). A limit sensor or the like (for example, a limit switch or a photosensor) used to detect the stylus 12 when returning to the origin is located at this mechanical origin.

[0047] On the other hand, the workpiece coordinate system is a coordinate system that can be defined by the user of the measuring device 1. The workpiece coordinate system is set, for example, by the user specifying an arbitrary point on the measurement object W or a jig for fixing the measurement object W as the origin of the workpiece coordinate system using machine coordinates.

[0048] Generally, a workpiece coordinate system is used as a coordinate system for outputting measurement results for measuring a measurement object W. When the measurement results of the measurement object W are output using the workpiece coordinate system, temperature correction is also performed based on the workpiece coordinate system.

[0049] Incidentally, floating-point numbers are used in numerical calculations using computers. When floating-point numbers are used, errors such as rounding errors can occur due to the number of significant digits of the computer (see, for example, IEEE 754-2019 (IEEE: Institute of Electrical and Electronics Engineers)). Errors caused by numerical calculations using floating-point numbers can also occur in numerical calculations for temperature compensation.

[0050] Figure 3 is a diagram showing the measurement results before and after the application of temperature compensation in the workpiece coordinate system. The horizontal and vertical axes in Figure 3 represent the scanning direction (X axis) during measurement and the displacement direction (Z axis) of the stylus 12, respectively. The sequence of points in Figure 3 indicates the detection positions on the surface of the measurement target W. It is also assumed that the temperature during measurement is higher than the standard temperature, and that the measurement results before the application of temperature compensation include the amount of thermal expansion.

[0051] In the measurement results before temperature compensation shown in Figure 3, the measurement starts near (X,Z)≒(100,100) in the work coordinate system, and the detector 10 is scanned in the +X direction, where the X coordinate increases. Therefore, the portion of the Z coordinate above the decimal point (the integer portion) is two to three digits, and the integer portion of the Z coordinate is three digits or more. This limits the number of digits available for calculating the decimal portion, which is the portion below the decimal point. When the number of digits available for calculating the decimal portion is reduced, the number of digits to which the value is rounded increases, resulting in larger rounding errors.

[0052] In this embodiment, by defining a coordinate system for temperature correction in the control unit 102, the number of digits in the integer part during temperature correction is minimized and the number of digits used in the numerical calculation of the decimal part is increased (for example, maximized). This allows the number of digits to be rounded down, thereby reducing rounding errors.

[0053] Figure 4 shows the measurement results before and after the application of temperature compensation using a temperature compensation coordinate system. The temperature compensation coordinate system is created by transforming (for example, translating) the workpiece coordinate system on the XZ plane so that the measurement start point of the measurement results before the application of temperature compensation becomes the origin (X, Z) = (0, 0). As shown in Figure 4, by setting the measurement start point to the origin (X, Z) = (0, 0), the measurement start point also coincides with the origin in the measurement results after the application of temperature compensation.

[0054] In the example shown in Figure 4, the integer part of the Z coordinate is one digit, and the integer part of the X coordinate is also one digit near the origin. This increases the number of digits available for calculating the decimal point, and reduces rounding errors.

[0055] 5 and 6 are diagrams showing examples in which temperature correction is applied to the measurement results of the contours of a rectangular parallelepiped and hemispherical measurement object W (e.g., a calibrator), respectively. Figures 5 and 6(b) show examples using a work coordinate system, and Figure 6(a) shows an example using a temperature correction coordinate system.

[0056] In this embodiment, the measurement results of the measurement object W are converted into a temperature correction coordinate system with the measurement start point as the origin, and the measurement results before temperature correction are temperature corrected on the XZ plane of the temperature correction coordinate system. This allows the measurement results of the measurement object W after temperature correction to be obtained, with the origin of the temperature correction coordinate system as the reference.

[0057] In the examples shown in FIGS. 4 to 6 , a temperature correction coordinate system with the measurement start point (X, Z) as its origin is used by translation. However, the temperature correction coordinate system is not limited to this. For example, in addition to translation, scaling or rotation may be performed to reduce the number of digits in the integer part of the measurement result. For example, the measurement result may be shrunk in the X or Z direction so that the number of digits in the integer part is a predetermined number or less. Furthermore, if the measurement result is tilted, the measurement result may be rotated so that it is approximately parallel to the X or Z axis so that the number of digits in the integer part is a predetermined number or less. Furthermore, the workpiece coordinate system may be moved in only one of the X and Z directions, and a temperature correction coordinate system in which only one of the X and Z coordinates of the measurement start point is set to 0 may be used to suppress rounding errors in the coordinate set to 0 at the measurement start point. Furthermore, to prevent the number of digits in the integer part of the X coordinate from exceeding a predetermined number (e.g., 1 to 2 digits), the measurement result before temperature correction may be divided in the X direction, and multiple temperature correction coordinate systems may be used.

[0058] The measurement results of the temperature correction coordinate system do not need to be displayed on the display unit 106 or the like, and may be used only for calculation processing within the control unit 102.

[0059] [Measurement method] FIG. 7 is a flowchart showing a measurement method (temperature correction method) according to one embodiment of the present invention.

[0060] First, the measurement object W is placed on the stage 50 and the detector 10 is scanned in the X direction to measure the measurement object W in a coordinate system for outputting measurement results (for example, a workpiece coordinate system). The control unit 102 acquires scale head detection values ​​from the scale head 24 and scale detection values ​​from the scale 58. The control unit 102 then uses the scale head detection values ​​and the scale detection values ​​to perform calculations on the shape, roughness, contour, etc. of the surface of the measurement object W. In this way, the control unit 102 acquires measurement results of the measurement object W including calculation results on the shape, roughness, contour, etc. of the surface of the measurement object W (step S10). The measurement results are stored in, for example, the storage 108.

[0061] Next, the control unit 102 converts the measurement results of the measurement object W into a temperature correction coordinate system (step S12). In step S12, coordinate conversion including parallel translation is performed so that the measurement start point of the measurement object W in the measurement result output coordinate system becomes the origin.

[0062] Next, the control unit 102 applies temperature correction to the measurement results of the measurement object W in the temperature correction coordinate system (step S14). For example, the coordinates of the measurement results converted into the temperature correction coordinate system are (X, Z), and the thermal expansion coefficient of the measurement object W is β ( / °C). In this case, the coordinates (X', Z') of (X, Z) after temperature correction (for example, the position of (X, Z) at standard temperature (20°C)) are expressed by the following equation:

[0063] X´=X+X*β*{20(℃)-(work temperature at time of measurement)} Z´ = Z + Z * β * {20 (℃) - (work temperature at time of measurement)} In the above example, temperature correction was performed for the thermal expansion (contraction) of the object to be measured W, but temperature correction can also be performed for the thermal expansion (contraction) of the stylus 12, the oscillating part 18, the scale 22 or the scale 58, etc., by providing temperature sensors for detecting the respective temperatures (for example, WO 2021-220595 specification).

[0064] Next, the control unit 102 performs an inverse transformation of the coordinate transformation of step S12 on the measurement results after the temperature correction, and converts them into a coordinate system for outputting the measurement results (step S16). The measurement results converted in step S16 are stored in the storage 108. The results are also output to the display unit 106 for user confirmation, etc. (step S18).

[0065] According to this embodiment, by using a temperature correction coordinate system, it is possible to suppress the influence of errors resulting from numerical calculations for temperature correction. [Explanation of symbols]

[0066] 1...measuring device, 10...detector, 12...stylus, 14...stylus section, 16...arm section, 18...oscillating section, 20...oscillating axis, 22...scale, 24...scale head, 26...detector housing, 50...measurement object placement section, 52...surface plate, 54...column, 56...carriage, 58...scale, 60X, 60Z...detector drive mechanism, 80...temperature sensor, 100...control device, 102...control section, 104...input section, 106...display section, 108...storage

Claims

1. a detector for measuring the object to be measured; a temperature sensor for measuring the temperature of the object to be measured; a control unit that converts the measurement results obtained by the detector into a temperature correction coordinate system having a measurement start point of the object as the origin, and applies temperature correction based on the temperature at the time of measurement to the measurement results converted into the temperature correction coordinate system; A measuring device comprising:

2. 2. The measurement device according to claim 1, wherein the control unit converts the measurement results into the temperature correction coordinate system by translating a measurement start point of the object in the measurement results measured based on a measurement result output coordinate system to the origin.

3. The measurement device according to claim 1 , wherein the control unit converts the measurement result after the temperature correction into a coordinate system for outputting measurement results and outputs the converted result.

4. a step of converting the measurement result of the measurement object into a temperature correction coordinate system having the measurement start point of the measurement object as the origin; applying temperature correction based on the temperature at the time of measurement of the measurement object to the measurement result converted into the temperature correction coordinate system; A measurement method comprising:

5. a function of converting the measurement result of the object to be measured into a temperature correction coordinate system having the measurement start point of the object to be measured as the origin; a function of applying temperature correction based on the temperature at the time of measurement of the measurement object to the measurement result converted into the temperature correction coordinate system; A measurement control program that enables a computer to achieve this.

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