JP7678966B2 - Surface texture measuring device - Google Patents

Description

The present invention relates to a correlation generating method, a measuring force adjusting method, and a surface texture measuring device.

A widely used contact detector for measuring surface texture is a lever-type detector that has a contactor that contacts the workpiece, an arm that supports the contactor, a swing support shaft that swingably supports the arm, and a sensor that detects the swing displacement of the arm. In a lever-type detector, an elastic body such as a coil spring is used to apply a measuring force that presses the contactor against the workpiece. The measuring force is adjusted using a measuring force adjustment mechanism. Setting the measuring force with precision has been an issue.

Patent Document 1 describes a contact-type internal diameter measuring instrument that performs measurements by bringing a contactor into contact with the object being measured. The device described in this document has a contactor at one end of a measuring arm that is supported so as to be able to swing at a swing fulcrum, and detects the displacement of the other end using a detector. The swing fulcrum of the arm provided in this device is configured using a cross spring. This configuration allows for a constant measuring force and enables highly accurate measurements.

Japanese Patent Application Publication No. 11-257905

However, if there are individual mechanical differences between devices, the measuring force actually applied to the object to be measured may differ even if the settings of the measuring force applying mechanism are the same. For this reason, it is necessary to actually measure the correlation between the settings of the measuring force applying mechanism and the measuring force for each device. Similar issues exist even when the arms, contacts, etc. are interchangeable.

The present invention was made in consideration of these circumstances, and aims to provide a correlation generation method, a measuring force adjustment method, and a surface texture measuring device that can perform simple, low-cost adjustment of the measuring force.

To achieve the above objective, the following aspects of the invention are provided:

The correlation generating method according to the first aspect is a correlation generating method for surface texture measurement in which an arm equipped with a contact is supported at a pivot point by a plate-shaped elastic member so that the arm can be pivoted, and a measuring force is applied to the contact via the arm by applying a biasing force to a portion of the arm opposite the contact across the pivot point using a measuring force applying unit, thereby detecting the displacement of the contact. The correlation generating method includes a detection step of detecting the displacement of the contact via the arm while changing the setting value of the measuring force applying unit corresponding to the biasing force with the contact not in contact with the workpiece, a calculation step of calculating the measuring force applied to the contact when the displacement is detected based on the detected displacement value and the physical property value of the plate-shaped elastic member, and a creation step of creating a correlation between the setting value of the measuring force applying unit and the measuring force based on the calculation result of the calculation step.

According to the first aspect, the contactor is not in contact with the object, and the displacement of the contactor is detected for the set values of the measuring force imparting mechanism. From the detection result of the contactor's displacement, the physical property value of the plate-shaped elastic member that supports the arm at the fulcrum of oscillation is used to derive the correlation between the measuring force imparted to the contactor and the set value of the measuring force imparting mechanism. This makes it possible to generate a correlation that can be applied to the measuring force adjustment in a simple and low-cost manner, without the need for a measuring device or the like that actually measures the measuring force.

The concept of adjusting the measuring force can include concepts such as the initial setting of the measuring force and the configuration after the measuring force is set.

In the second aspect, in the correlation generating method of the first aspect, the correlation may be configured to apply a measuring force derived using F _meas = B x D/(L x L arm x L tip), where F meas is the measuring _force , B is the bending stiffness of the plate-shaped elastic member, D is the detection value of the displacement detection position in _{the arm} , L is the length of the plate-shaped elastic member, L _arm is the distance from the oscillation fulcrum to the displacement detection position, and L _tip is the distance from the oscillation fulcrum to the contact.

According to the second aspect, the measuring force F meas can be derived from the detection value D of the displacement of the contactor using the bending stiffness B of the plate-shaped elastic member, the detection value D of the displacement of the contactor, the length L of the plate-shaped elastic member, the distance L _arm from the fulcrum of oscillation to the displacement detection position on the arm, and the _distance L _tip from the fulcrum of oscillation to the contactor.

The measuring force adjustment method according to the third aspect is a measuring force adjustment method that adjusts the measuring force using the correlation created by the correlation generation method described in the first aspect, and includes an input step of inputting a measuring force value, a determination step of determining a setting value of the measuring force imparting unit corresponding to the measuring force value by referring to the correlation, and an adjustment step of operating the measuring force imparting unit to adjust the measuring force imparted to the contact based on the setting value of the measuring force imparting unit determined in the determination step.

According to the third aspect, it is possible to adjust the measurement force using the correlation described in the first aspect.

The fourth aspect may be configured such that the measurement force adjustment method of the third aspect includes a correlation selection step of selecting a correlation according to the measurement conditions from a plurality of correlations.

According to the fourth aspect, the measurement force can be adjusted according to the measurement conditions.

The surface texture measuring device according to the fifth aspect includes a contactor, an arm to which the contactor is attached, an arm support section that supports the arm to be able to swing at the swing fulcrum of the arm using a plate-shaped elastic member, a measuring force imparting section that imparts a measuring force to the contactor via the arm by applying a biasing force to a part of the arm on the opposite side of the swing fulcrum from the contactor, a detection section that detects the displacement of the contactor via the arm, and a correlation storage section that stores the correlation between the setting value of the measuring force imparting section and the measuring force, and the correlation is determined by detecting the displacement of the contactor while changing the setting value of the measuring force imparting section that corresponds to the biasing force with the contactor out of contact with the workpiece, calculating the measuring force imparted to the contactor when the displacement is detected based on the detected displacement value and the physical property value of the plate-shaped elastic member, and applying the correlation between the setting value of the measuring force imparting section and the measuring force generated based on the calculation result.

According to the fifth aspect, it is possible to adjust the measuring force using the correlation described in the first aspect.

According to the present invention, the contactor is not in contact with the object, and the displacement of the contactor is detected for multiple set values of the measuring force imparting mechanism. From the detection result of the contactor's displacement, the physical property value of the plate-shaped elastic member that supports the arm at the fulcrum of oscillation is used to derive the correlation between the measuring force imparted to the contactor and the set value of the measuring force imparting mechanism. This makes it possible to generate a correlation that can be applied to measuring force adjustment in a simple, low-cost manner, without the need for a measuring device that actually measures the measuring force.

FIG. 1 is a diagram showing the overall configuration of a roundness measuring device according to an embodiment of the present invention. FIG. 2 is a functional block diagram of the roundness measuring device shown in FIG. FIG. 3 is a flow chart showing the steps of a measuring force adjustment method applied to the roundness measuring apparatus shown in FIG. FIG. 4 is a conceptual diagram of a lever type detector. FIG. 5 is a schematic diagram showing an example of the configuration of a detector applied to the roundness measuring apparatus shown in FIG. FIG. 6 is a schematic diagram showing the relationship between the setting value of the measuring force imparting mechanism and the detection value of the displacement sensor. FIG. 7 is a detailed explanatory diagram of the rotational moment generated by the leaf spring. FIG. 8 is an explanatory diagram of the calculation of the measuring force generated by the leaf spring. FIG. 9 is an explanatory diagram for calculating the measuring force acting on the contact. FIG. 10 is a graph showing the detected value of the displacement sensor versus the set value of the measuring force imparting mechanism. FIG. 11 is a graph showing the measuring force versus the setting value of the measuring force imparting mechanism. FIG. 12 is a schematic diagram of a leaf spring applied to the swing fulcrum of the arm. FIG. 13 is a schematic diagram of a cross spring applied to the swing fulcrum of the arm. FIG. 14 is a schematic diagram of a detection unit having replaceable contacts. FIG. 15 is a schematic diagram of a detection unit having a different shape of contact. FIG. 16 is a schematic diagram showing different mounting angles of the contacts relative to the arms.

Below, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. In this specification, the same components are given the same reference symbols, and duplicate explanations will be omitted as appropriate.

[Roundness measuring device]
[Overall configuration of roundness measuring device]
1 is a diagram showing the overall configuration of a roundness measuring device according to an embodiment. The roundness measuring device 10 shown in the figure measures the roundness of a cylindrical workpiece 9. The workpiece 9 to be measured may have a disk shape, a cylindrical shape, or the like.

The roundness measuring device 10 includes a base 11. The base 11 is a support table that supports each part of the roundness measuring device 10. The support table is synonymous with the base. The roundness measuring device 10 includes a table 13. The table 13 is sometimes called a workpiece table.

The table 13 is disk-shaped and is attached to the upper surface of the base 11. The table 13 is rotatably supported by the base 11 at the position of a rotation axis 22 that passes through the center of the table 13 and extends in the vertical direction. The inclination of the table 13 with respect to a horizontal reference plane is adjusted so that the table 13 is parallel to the reference plane.

Here, the term "upward" in this specification refers to the vertically upward direction. The term "downward" refers to the vertically downward direction.

The workpiece 9 is placed on the top surface of the table 13. The workpiece 9 is placed on the top surface of the table 13 so that the center of the shape of the part to be measured coincides with the axis of rotation. Figure 1 shows an example in which the outer peripheral surface of the cylindrical workpiece 9 is the part to be measured, and the workpiece 9 is placed so that the central axis of the cylinder coincides with the axis of rotation 22 of the table 13.

The roundness measuring device 10 includes a motor 14. The motor 14 is disposed inside the base 11. The rotation shaft of the motor 14 is connected to the rotation shaft of the table 13 via a drive transmission mechanism. The motor 14 rotates the table 13 around the rotation shaft 22 as the center of rotation. The drive transmission mechanism may include a gear. The drive transmission mechanism is not shown in the figure.

The roundness measuring device 10 includes a column 15, a carriage 16, a horizontal arm 17, and a detector 18. The column 15 is the upper surface of the base 11 and is disposed on a lateral side of the base 11 in the horizontal direction. The column 15 is a pillar that extends in the vertical direction.

The carriage 16 is supported by a column 15 so that it can rise and fall. A horizontal arm 17 is attached to the carriage 16 so that it can move horizontally. A detector 18 is attached to the tip of the horizontal arm 17.

The detector 18 includes a contact 18A and a displacement sensor. Note that the displacement sensor is not shown in FIG. 1. The displacement sensor is shown in FIG. 2 using the reference symbol 18B. The detector 18 detects the displacement of the contact 18A moving along the direction indicated by the reference symbol A. The detector 18 outputs a detection signal representing the displacement of the contact 18A. The detection signal is transmitted to the control device 19.

The detector 18 is equipped with a measuring force imparting mechanism. The measuring force imparting mechanism imparts a measuring force corresponding to a set value of the measuring force to the contact 18A. Note that the measuring force imparting mechanism is not shown in FIG. 1. The measuring force imparting mechanism is illustrated in FIG. 2 using the reference numeral 56.

The roundness measuring device 10 is equipped with a control device 19. A display device 19A and an input device 19B are connected to the control device 19. A display device such as a liquid crystal display may be used as the display device 19A. A keyboard and mouse may be used as the input device 19B. A touch panel type display device may be used as the display device 19A and the input device 19B.

[Explanation of the control device]
Fig. 2 is a functional block diagram of the roundness measuring device shown in Fig. 1. The control device 19 includes a detection signal acquiring unit 40 and a signal processing unit 42. The detection signal acquiring unit 40 acquires a detection signal transmitted from the detector 18. The detection signal acquiring unit 40 stores the detection result using the detection signal storage unit 44. The signal processing unit 42 generates a measurement result of the workpiece 9 using the detection signal of the detector 18. The signal processing unit 42 stores the measurement result using the measurement result storage unit 46.

The control device 19 includes a display control unit 48. The display control unit 48 controls the display device 19A. The signal processing unit 42 transmits an electrical signal representing the measurement result to the display control unit 48. The display control unit 48 converts the electrical signal representing the measurement result into a display signal applied to the display device 19A, and transmits the display signal to the display device 19A. The display device 19A displays the measurement result of the detector 18 represented by the display signal transmitted from the display control unit 48.

The control device 19 includes a measuring force application control unit 50, a measuring force setting unit 52, and a table storage unit 54. The measuring force application control unit 50 controls the operation of the measuring force application mechanism 56 provided in the detector 18. The measuring force setting unit 52 sets the measuring force, which is a control parameter of the measuring force application mechanism 56.

The table storage unit 54 stores a measuring force setting table 58 that indicates the correlation between the setting value of the measuring force imparting mechanism 56 and the measuring force imparted to the contact. The measuring force imparting control unit 50 controls the operation of the measuring force imparting mechanism 56 based on the setting value of the measuring force setting unit 52. The table storage unit 54 shown in the embodiment corresponds to an example of a correlation storage unit. Details of the operation control of the measuring force imparting mechanism 56 will be described later.

The control device 19 includes a drive control unit 60. The drive control unit 60 controls the operation of the drive mechanism 62 based on the control parameters of the drive mechanism 62. The drive mechanism 62 may include the motor 14 shown in FIG. 1, a motor that operates the carriage 16, and a motor that operates the horizontal arm 17.

The control device 19 includes an input unit 64. The input unit 64 acquires an input signal transmitted from the input device 19B. The input unit 64 transmits information corresponding to the input signal to each part of the control device 19. For example, when a setting value for a control parameter is input using the input device 19B, the input unit 64 transmits the control parameter corresponding to the acquired input signal to the corresponding control unit.

The control device 19 includes a program storage unit 66. The program storage unit 66 stores various programs that are applied to the roundness measuring device 10 and the control device 19. One example of a program is a measuring force adjustment program that is used to adjust the measuring force applied to the contact.

[Hardware configuration of the control device]
The control device 19 may be a computer. The control device 19 uses hardware described below to execute a specified program to realize the functions of the roundness measuring device 10. Various processors may be applied to the hardware of each control unit. An example of a processor is a CPU (Central Processing Unit). The CPU executes the program to function as various processing units.

Figure 3 is a flow chart showing the steps of a measuring force adjustment method applied to the roundness measuring device shown in Figure 1. In the measuring force setting step S10, the measuring force setting unit 52 shown in Figure 2 sets the measuring force to be applied to the measurement of the workpiece 9. Note that the measuring force setting step S10 described in the embodiment corresponds to an example of an input step for inputting the value of the measuring force. The measurement of the workpiece 9 described in the embodiment corresponds to an example of surface texture measurement.

The measuring force is determined according to the measurement conditions, such as the specifications of the workpiece 9, the measurement accuracy, and the contact 18A. The measuring force setting unit 52 sets the measuring force based on the measurement conditions applied to the measurement of the workpiece 9. After the measuring force setting process S10, the process proceeds to the measuring force setting information acquisition process S12. Note that the setting of the measuring force described in the embodiment corresponds to an example of inputting the value of the measuring force.

In the measuring force setting information acquisition step S12, the measuring force application control unit 50 acquires input information of the measuring force set in the measuring force setting step S10. An example of the measuring force setting information is the setting value of the measuring force application mechanism 56. The setting values of the measuring force application mechanism 56 are indicated in Fig. 6 using the symbols S _V. After the measuring force setting information acquisition step S12, the process proceeds to an operation parameter reading step S14.

In the operation parameter reading step S14, the measuring force application control unit 50 reads out the operation parameters corresponding to the measuring force setting information from the measuring force setting table 58. After the operation parameter reading step S14, the process proceeds to the operation parameter setting step S16.

In the operation parameter setting step S16, the measuring force application control unit 50 sets the operation parameters of the measuring force application mechanism 56 read in the operation parameter reading step S14. After the operation parameter setting step S16, the process proceeds to the measurement application mechanism operation step S18. Note that the operation parameter reading step S14 and the operation parameter setting step S16 described in the embodiment correspond to an example of a component of the determination step.

In the measurement mechanism operation step S18, the measurement force application control unit 50 operates the measurement force application mechanism 56 based on the operation parameters set in the operation parameter setting step S16. After the measurement mechanism operation step S18, the process proceeds to the adjustment completion confirmation step S20.

In the adjustment completion confirmation step S20, the measuring force imparting control unit 50 determines whether or not the adjustment of the measuring force imparting mechanism 56 is completed. The measuring force imparting control unit 50 may determine whether or not the adjustment of the measuring force imparting mechanism 56 is completed based on the detection result of a position sensor that detects the position of the measuring force imparting mechanism 56.

In the adjustment completion confirmation step S20, if the measuring force application control unit 50 determines that the adjustment of the measuring force application mechanism 56 is not complete, the result is No. If the result is No, the process proceeds to the measurement application mechanism operation step S18, and the measurement application mechanism operation step S18 and the adjustment completion confirmation step S20 are repeatedly performed until the adjustment completion confirmation step S20 results in a Yes result.

On the other hand, in the adjustment completion confirmation step S20, if the measuring force application control unit 50 determines that the adjustment of the measuring force application mechanism 56 is completed, a Yes judgment is made. If a Yes judgment is made, the measuring force application control unit 50 ends the measuring force adjustment method.

Note that the measurement mechanism operation process S18 and the adjustment completion confirmation process S20 shown in the embodiment correspond to examples of components of the adjustment process.

When the table storage unit 54 shown in FIG. 2 stores multiple measuring force applying mechanisms 56, a table switching process may be performed to switch the measuring force setting table 58 depending on the measurement conditions of the workpiece 9. In this embodiment, the table switching process may be performed after the measurement condition acquisition process for acquiring the measurement conditions of the workpiece 9 is performed.

The control device 19 may cause the display device 19A to display the identification information of the measuring force setting table 58 applied to the measurement value adjustment. That is, a measuring force setting table identification information display process may be performed to display the identification information of the measuring force setting table 58 applied to the measurement value adjustment.

The control device 19 may generate a new measuring force setting table 58. That is, if there is no measuring force setting table 58 that matches the measurement conditions such as the type of arm and the mounting direction of the arm in the operation parameter reading process S14, a table creation process may be performed in which the detection value of the displacement sensor 208 is read for each measurement force setting value while the contact 202 is not in contact with the object to be measured 210, the measurement force is calculated from the detection value of the displacement sensor 208, and a new measuring force setting table 58 is created.

The table creation process shown in the embodiment corresponds to an example of a correlation creation process. Each measurement force setting value shown in the embodiment corresponds to an example of each measurement force setting. According to this aspect, it is possible to adjust the measurement force for new measurement conditions.

When the control device 19 is provided with multiple measuring force setting tables 58, it can perform a table selection process to select a measuring force setting table 58 according to the measurement conditions. The table selection process shown in the embodiment corresponds to an example of a correlation selection process. According to this aspect, it is possible to adjust the measuring force according to the measurement conditions.

[Description of a typical lever detector]
4 is a conceptual diagram of a lever detector. The lever detector 100 includes a contactor 102, an arm 104, a measuring force imparting mechanism 106, and a displacement sensor 108. The lever detector 100 brings the contactor 102 into contact with an object to be measured 110, and moves the contactor 102 and the object to be measured 110 relatively to detect unevenness on the surface of the object to be measured 110. The contactor 102 corresponds to the contactor 18A shown in FIG. 1. The object to be measured 110 corresponds to the workpiece 9.

The arm 104 shown in FIG. 4 holds the contact 102 at its tip. The arm 104 is supported so as to be able to swing using a swing fulcrum 112. The arrow line attached to the swing fulcrum 112 indicates the swing direction of the arm 104.

The measuring force imparting mechanism 106 applies a biasing force to the arm 104 to adjust the measuring force with which the contact 102 is pressed against the object to be measured 110. The measuring force imparting mechanism 106 includes an elastic body such as a coil spring 114 that generates a measuring force. One end of the coil spring 114 is connected to the arm 104. The other end of the coil spring 114 is connected to a lifting mechanism. The arrow line on the measuring force imparting mechanism 106 indicates the direction of movement of the other end of the coil spring 114. The lifting mechanism is not shown in the figure.

The displacement sensor 108 detects the displacement of the displacement detection position 116, which is the base end position of the arm 104. The lever detector 100 outputs an output signal representing the detection result of the displacement sensor 108. The measuring force applied to the object to be measured 110 is set and adjusted using the measuring force application mechanism 106, but the setting accuracy of the measuring force is an issue in ensuring the measurement accuracy for measuring the surface properties of the object to be measured 110.

For ease of explanation, FIG. 4 illustrates an example in which the tip of the contact 102 faces downward, but the lever detector illustrated in FIG. 4 may have the tip of the contact 102 facing horizontally or facing upward, similar to the detector 18 illustrated in FIG. 1. The same applies to the detector 200 illustrated in FIG. 5.

[Example of the configuration of a detector applied to the roundness measuring device according to this embodiment]
Fig. 5 is a schematic diagram showing an example of the configuration of a detector applied to the roundness measuring apparatus shown in Fig. 1. The detector 200 includes a contact 202, an arm 204, a measuring force imparting mechanism 206, and a displacement sensor 208. The measuring force imparting mechanism 206 includes a coil spring 214.

The contactor 202 shown in FIG. 5 corresponds to the contactor 18A shown in FIG. 1. The object to be measured 210 corresponds to the workpiece 9. Reference numeral 212 denotes the pivot point of the arm 204. Reference numeral 216 denotes the displacement detection position of the arm 204.

In FIG. 5, the base end of the arm 204 is used as the displacement detection position 216, but the displacement detection position 216 can be any position of the arm 204 on the opposite side of the contact 202 with respect to the pivot fulcrum 212.

The detector 200 has a leaf spring 220 applied to a support member that supports the arm 204 so that it can swing. The midpoint of the leaf spring 220 serves as the swing fulcrum 212 of the arm 204. The arrow line on the arm 204 indicates the swing direction of the arm 204. The leaf spring 220 is connected to the arm 204 using an arm connecting member 222. The arm 204 is connected to the leaf spring 220 at a position closer to the contact 202 than the swing fulcrum 212.

The leaf spring 220 is connected to a frame 226 that supports the displacement sensor 208 using a frame connecting member 224. The detector 200 measures the object 210 by applying a specified measuring force using the correlation between the setting value of the measuring force applying mechanism 206 and the measuring force.

Using the physical properties of the leaf spring 220, the measuring force is calculated from the detection value of the displacement sensor 208, and the correlation between the setting value of the measuring force imparting mechanism 206 and the detection value of the displacement sensor 208 is derived.

The measuring force setting table 58 shown in FIG. 2 can be applied to the correlation between the setting value of the measuring force imparting mechanism 206 and the measuring force. The measuring force imparting mechanism 206 corresponds to the measuring force imparting mechanism 56 shown in FIG. 2. The calculation of the measuring force is described in detail below.

The leaf spring 220 shown in the embodiment corresponds to an example of a component of an arm support section that supports an arm using a plate-shaped elastic member. The leaf spring 220 shown in the embodiment corresponds to an example of a plate-shaped elastic member. Furthermore, the measuring force imparting mechanism 206 described in the embodiment corresponds to an example of a measuring force imparting section.

[Explanation of derivation of correlation between setting value of measuring force imparting mechanism and measuring force]
Fig. 6 is a schematic diagram showing the relationship between the setting value of the measuring force imparting mechanism and the detection value of the displacement sensor. A detection process is carried out to detect the detection value of the displacement sensor 208 for each setting value S _V of the measuring force imparting mechanism 206 according to the following procedure. Fig. 6 shows a schematic diagram of the setting value S _V of the measuring force imparting mechanism 206. First, the contactor 202 is set in a free state. That is, the contactor 202 is set in a non-contact state with the object to be measured 210 shown in Fig. 5.

Next, a set value S _V of the measuring force imparting mechanism 206 is determined. The set value S _V is the movement distance of the lifting mechanism provided in the measuring force imparting mechanism 206 relative to a reference position. The movement distance when the lifting mechanism is raised relative to the reference position is set to a positive value, and the movement distance when the lifting mechanism is lowered relative to the reference position is set to a negative value. The arrow line attached to the measuring force imparting mechanism 206 represents the lifting of the lifting mechanism.

The reaction force of the leaf spring 220 according to the set value S _V acts on the arm 204, the rotation moment generated by the leaf spring 220 and the rotation moment generated by the measuring force imparting mechanism 206 are balanced, and the swing of the arm 204 stops.

The arrow drawn at a position on the tip side of the swing fulcrum 212 of the arm 204 shown in FIG. 6 represents the rotational moment generated by the leaf spring 220. The arrow drawn at the connection position 204B of the coil spring 214 in the arm 204, which is the part of the arm opposite the contact 202 across the swing fulcrum 212 of the arm 204, represents the rotational moment generated by the measuring force imparting mechanism 206. The same applies to FIG. 7 and FIG. 9.

The rotational moment generated by the leaf spring 220 is the force moment acting on the connection position 204A of the leaf spring 220 in the arm 204. The rotational moment generated by the measuring force imparting mechanism 206 is the force moment acting on the connection position 204B of the coil spring 214 in the arm 204.

A detection value D of the displacement sensor 208 is obtained when the swing of the arm 204 is stationary. Using the physical property values of the leaf spring 220, a reaction force of the leaf spring 220 corresponding to a set value S _V of the measuring force imparting mechanism 206 is calculated from the detection value D of the displacement sensor 208. From the reaction force of the leaf spring 220, it is possible to calculate a measuring force to be imparted to the contact 202 corresponding to the force generated by the leaf spring 220.

The setting value S _V of the measuring force imparting mechanism 206 is changed, and the measuring force is calculated for each of the setting values S _V of the measuring force imparting mechanism 206. A correlation between the setting value S _V of the measuring force imparting mechanism 206 and the measuring force is derived based on the calculation results. The calculation of the measuring force described in the embodiment corresponds to an example of a calculation process. The procedure for generating the correlation described in the embodiment corresponds to an example of a correlation generating method. The calculation of the measuring force will be described in detail below.

6 using a solid line represents the case where the set value S _V of the measuring force imparting mechanism 206 is any value except zero. The contactor 202 and arm 204 shown in the figure using a dashed dotted line represents the case where the set value S _V of the measuring force imparting mechanism 206 is zero. The detection value D of the displacement sensor 208 when the set value S _V of the measuring force imparting mechanism 206 is zero is taken as the reference value. In the following description, the reference value is taken as zero. The detection value D of the displacement sensor 208 is the displacement of the displacement detection position 216 of the arm 204.

The displacement of the displacement detection position 216 of the arm 204 is expressed as the distance to the position of the displacement detection position 216 of the arm 204 when the set value S _V of the measuring force imparting mechanism 206 is zero. The displacement of the displacement detection position 216 of the arm 204 is expressed in a unit representing a distance, such as millimeters.

Reference character P _A denotes a reaction force of the leaf spring 220. The reaction force P _A acts on a connection position 204A of the leaf spring 220 at the arm 204. Reference character F _mf denotes a force generated by the coil spring 214. The force F _mf generated by the coil spring 214 forms an angle φ with the arm 204.

The symbol L represents the length of the leaf spring 220 along the longitudinal direction of the arm 204. The length L of the leaf spring 220 is the length of the portion of the leaf spring 220 that can be elastically deformed, and the length of the leaf spring 220 in its undeformed state is applied. The length L of the leaf spring 220 is a fixed value.

[Calculation of rotational moment generated by leaf spring]
7 is a detailed explanatory diagram of the rotation moment generated by the leaf spring. The symbol L _arm is the distance from the swing fulcrum 212 of the arm 204 to the displacement detection position 216. The symbol θ is the angle of the arm 204 when the setting value S _V of the measuring force imparting mechanism 206 is an arbitrary value with respect to the arm 204 when the setting value S _V of the measuring force imparting mechanism 206 is zero.

The rotation moment generated by the reaction force of the leaf spring 220 is expressed as (L/2)× _PA , where L is the length of the leaf spring 220 and _PA is the reaction force of the leaf spring 220. For convenience of calculation, the swing fulcrum 212 of the arm is set to the midpoint of the leaf spring 220. The midpoint of the leaf spring 220 is the midpoint of the portion of the leaf spring 220 that is elastically deformable.

[Calculation of measuring force generated by leaf spring]
8 is an explanatory diagram of the calculation of the measuring force generated by the leaf spring. The displacement δ(x) at a position whose distance from the base end 220A of the leaf spring 220 is x is expressed as δ(x)=(P×L×x ² )/[(6×B)×{3−(x/L)}].

Here, the force P generated by the leaf spring 220 has the same magnitude as the reaction force P _A of the leaf spring 220 shown in Fig. 7 and is directed in the opposite direction to the reaction force P _A of the leaf spring 220. B is the bending stiffness and is expressed as B = (b x t ³ x E) / {12 x (1 - v ² )}.

b is the width of the leaf spring 220. The width of the leaf spring 220 is the total length of the leaf spring 220 in the width direction perpendicular to the direction of the length L of the leaf spring 220. t is the thickness of the leaf spring 220. E is the Young's modulus of the leaf spring 220. ν is the Poisson's ratio of the leaf spring 220.

The arm angle θ(x) of the detector 200 at a position that is a distance x from the base end 220A of the leaf spring 220 is expressed as θ(x)={δ(x+dx)-δ(x)}/dx. In other words, the arm angle θ(x) of the detector 200 is dδ(x)/dx, which is the differentiation of δ(x) with respect to x. The arm angle θ(x) of the detector 200 is expressed as θ(L)=(P×L ² )/(2×B), with the length L of the leaf spring 220 as a parameter.

Here, the arm angle θ(x) of the detector 200 shown in Fig. 8 is the angle θ shown in Fig. 7. In Fig. 8, the arm 204 is shown typically by using a dashed line. Meanwhile, the tangent of θ is expressed as tan(θ)=D/L _arm , using the distance L _arm from the swing fulcrum 212 of the arm 204 to the displacement sensor 208 and the detection value D of the detector 200.

Applying the small angle approximation, setting tan(θ)=θ, the above equation is solved for P to obtain P(D)=(2×B×D)/( ^L2 ×L _arm ). The force P generated by the leaf spring 220 is expressed as a function with the detection value D of the detector 200 as a parameter.

In the above P(D), the bending stiffness B of the leaf spring 220 and the length L of the leaf spring 220 are defined as the physical properties of the leaf spring 220. In addition, the distance L _arm from the swing fulcrum 212 of the arm 204 to the displacement sensor 208 is defined based on the mechanical specifications of the arm 204.

[Calculation of the measuring force acting on the contact]
9 is an explanatory diagram for calculating the measuring force acting on the contact tip. The distance from the swing fulcrum 212 of the arm 204 to the position of the contact tip 202 is denoted by L _tip , and the measuring force acting on the contact tip 202 is denoted by F _meas .

The rotational moment generated by the measuring force imparting mechanism 206 is expressed as (L/2)×P=B×D/(L×L _arm ). The rotational moment generated by the measuring force imparting mechanism 206 is balanced with F _meas ×L _tip . That is, F _meas acting on the contact 202 is expressed as F _meas (D)=B×D/(L×L _arm ).

[Explanation of measuring force setting table]
10 is a graph showing the detected value of the displacement sensor versus the set value of the measuring force imparting mechanism. The horizontal axis of the graph shown in this figure is the set value S _V of the measuring force imparting mechanism 206, and the vertical axis is the detected value D of the displacement sensor 208.

The set value S _V of the measuring force imparting mechanism 206 may be an operating parameter of a moving mechanism that moves the coil spring 214 shown in Fig. 5 etc. When the moving mechanism is equipped with a controlled motor such as a pulse motor, the control parameter may be the number of pulses corresponding to the moving distance of the coil spring 214.

The set value S _V of the measuring force imparting mechanism 206 is changed, and the detection value D of the displacement sensor 208 is measured for a plurality of set values S _V. The plot representing the measured values is subjected to processing such as linear interpolation and data extrapolation to generate the graph shown in FIG.

Fig. 11 is a graph showing the measuring force versus the setting value of the measuring force imparting mechanism. The horizontal axis of the graph shown in Fig. 11 is the setting value S _V of the measuring force imparting mechanism 206, as in the graph shown in Fig. 10. The vertical axis of the graph shown in Fig. 11 is the measuring force F _meas acting on the contact 202. The unit of the measuring force F _meas is millinewtons.

The graph shown in Fig. 11 can be derived by applying the detection value D of the displacement sensor 208 shown in Fig. 10 to F _meas (D) = B x D / (L x L _arm x L _tip ). The graph shown in Fig. 11 is an example of the measuring force setting table 58 shown in Fig. 2. The measuring force imparting control unit 50 shown in Fig. 2 refers to the measuring force setting table 58, reads out the setting value S V of the measuring force imparting mechanism 206 as the operating parameter of the measuring force imparting mechanism 206 corresponding to the measuring force F _meas set by the measuring force setting unit ₅₂ , and operates the measuring force imparting mechanism 206 based on the setting value S _V of the measuring force imparting mechanism 206.

[Preferable embodiment for creating measuring force setting table]
<Extrapolation>
When detecting the detection value D of the displacement sensor 208 relative to the setting value S _V of the measuring force imparting mechanism 206, there may be a setting value S _V of the measuring force imparting mechanism 206 for which the detection value D of the displacement sensor 208 falls outside the detection range. In such a case, the setting value S _V of the measuring force imparting mechanism 206 corresponding to the detection value D of the displacement sensor 208 falling outside the detection range may be interpolated by extrapolating the plot in the graph shown in Fig. 10. A known approximation method such as polynomial approximation may be applied for extrapolating the plot.

<Linear characteristics>
The measuring force F _meas with respect to the set value S _V of the measuring force imparting mechanism 206 has a linear characteristic. This can improve the accuracy of extrapolation of the plot. The linearity here is not limited to a strict linearity. Even if it is nonlinear, a substantial linearity that can obtain the same effect as a linearity may be applied.

<Updating the measuring force setting table>
The measuring force setting table 58 may be generated and stored in the initial state of the roundness measuring apparatus 10. The measuring force setting table 58 may be updated in accordance with the state of the detector 200 and the object to be measured 110. The term "update" as used herein may include both a mode in which an existing table is rewritten and a mode in which a new table is added while the existing table is left unchanged.

When the measuring force setting table 58 is updated, it is preferable to store the update information. That is, the roundness measuring device 10 may be provided with an update information storage unit that stores the update information of the measuring force setting table 58. The update information may include information such as the update date and time.

[Explanation of Plate-shaped Elastic Member]
Fig. 12 is a schematic diagram of a leaf spring applied to the swing fulcrum of an arm. The single leaf spring 300 shown in Fig. 12 is composed of a single leaf having a flat plate shape. The single leaf spring 300 shown in Fig. 12 is applied to the leaf spring 220 shown in Fig. 5 and the like.

One side of the single-plate leaf spring 300 is supported by a swing-side connecting member 302, and the other side is supported by a fixed-side swinging member 304. The swing-side connecting member 302 corresponds to the arm connecting member 222 shown in FIG. 5, etc. The swing-side connecting member 302 is connected to the contact 202 and core shown in FIG. 5, etc. The fixed-side swinging member 304 corresponds to the frame connecting member 224. The fixed-side swinging member 304 is connected to the main body side of the detector 200.

Figure 13 is a schematic diagram of a cross spring applied to the swing fulcrum of an arm. The cross spring 320 shown in Figure 13 has improved characteristics as a rotation bearing compared to the single-plate leaf spring 300 shown in Figure 12.

The cross spring 320 shown in FIG. 13 is supported using a swing-side connecting member 322 and a fixed-side swinging member 324. The function of the swing-side connecting member 322 is similar to that of the swing-side connecting member 302 shown in FIG. 12. The function of the fixed-side swinging member 324 is similar to that of the fixed-side swinging member 304. The cross spring 320 shown in FIG. 13 corresponds to an example of a plate-shaped elastic member.

[Action and Effect]
[Zero point calibration of displacement sensor detection value]
In an operation of reading the detection value D of the displacement sensor 208 while changing the set value S _V of the measuring force imparting mechanism 206, the set value S _V of the measuring force imparting mechanism 206 at which the detection value D of the displacement sensor 208 becomes zero is detected. This makes it possible to detect the set value S _V of the measuring force imparting mechanism 206 at which the measuring force F _meas becomes neutral.

Figure 14 is a schematic diagram of a detection unit equipped with replaceable contacts. Figure 15 is a schematic diagram of a detection unit with different contact shapes, etc. Figure 16 is a schematic diagram of cases where the attachment angle of the contacts relative to the arm is different.

14, in a detector 200A in which the contact 202A is changed depending on the purpose of measurement, etc., the zero point of the detection value D of the displacement sensor 208 changes depending on the shape, etc. of the contact 202. If the measuring force adjustment shown in this embodiment is not performed, it is necessary to directly measure the measuring force F _meas using a measuring device such as a scale for the state of the contact 202A.

The detector 200A shown in FIG. 14 is capable of replacing the contact 202A with the detector 200 shown in FIG. 5, etc., and the rotational moment relative to the contact 202 changes depending on the mass of the contact 202A.

The detector 200B shown in FIG. 15 has a contact 202 that is different in shape and mass from the contact 202 provided in the detector 200 shown in FIG. 5, etc., and the rotational moment relative to the contact 202 changes depending on the mass and shape of the contact 202B.

The detector 200C shown in FIG. 16 has a different attachment angle of the contact 202C compared to the contact 202 provided in the detector 200 shown in FIG. 5, etc., and the rotational moment relative to the contact 202 changes depending on the attachment angle of the contact 202C.

The detector 200A shown in FIG. 14, the detector 200B shown in FIG. 15, and the detector 200C shown in FIG. 16 can calibrate the zero point of the detection value D of the displacement sensor 208 with respect to the setting value S _V of the measuring force imparting mechanism 206 by using the measuring force setting table 58 shown in FIG. 2.

[No need for measuring devices such as scales that directly measure the measuring force]
The measuring force can be adjusted and calibrated more simply and at lower cost. Furthermore, on-site work can be performed at the installation site of the roundness measuring device 10, and accurate calibration of the measuring force can be performed in the actual operating environment of the roundness measuring device 10. Furthermore, the latest calibrated value of the measuring force can always be used. This improves the reproducibility of the measurement results of the roundness measuring device 10, and makes it possible to achieve high-precision measurements.

[Elimination of the effects of individual differences in detectors, contacts, etc.]
When there are individual differences between the detector 200 and the contact 202, it is necessary to manage the correlation between the setting value S _V of the measuring force imparting mechanism 206 and the measuring force F _meas for each individual roundness measuring device 10. In addition, the management of the individual devices is time-consuming, and there is a concern that setting errors and the like may occur.

In contrast, the roundness measuring device 10 shown in this embodiment does not require the effort of individual management such as inputting serial numbers, and can reduce the occurrence of setting errors and the like and reduce the processing time for individual management.

[Application example]
In this embodiment, a roundness measuring device 10 that measures the roundness, straightness, parallelism, squareness, etc. of the workpiece 9 has been described as an example of a surface property measuring device that measures the surface shape of the workpiece 9, but the present invention is not limited to this and may be any of various surface property measuring devices such as a surface roughness measuring device and a contour shape measuring device.

The above-described embodiment of the present invention may have its constituent elements modified, added, or deleted as appropriate without departing from the spirit of the present invention. The present invention is not limited to the above-described embodiment, and many modifications may be made by a person having ordinary knowledge in the relevant field within the technical concept of the present invention.

10...Circularity measuring device, 19...Control device, 19A...Display device, 48...Display control unit, 50...Measuring force application control unit, 54...Table storage unit, 56, 206...Measuring force application mechanism, 58...Measuring force setting table, 66...Program storage unit, 200, 200A, 200B, 200C...Detector, 202, 202A, 202B, 202C...Contactor, 204...Arm, 208...Displacement sensor, 212...Oscillation fulcrum, 220...Leaf spring, 222...Arm connecting member, 224...Frame connecting member, 300...Single leaf spring, 302, 322...Oscillation side connecting member, 304, 324...Fixed side oscillation member, 320...Cross spring

Claims (4)

A contact and
an arm to which the contact is attached;
an arm support portion that supports the arm so that the arm can swing using an elastic member at a swing fulcrum of the arm;
a measuring force applying unit that applies a measuring force to the contact via the arm by applying a biasing force to the arm;
a detection unit that detects a displacement of the contact via the arm;
a correlation storage unit for storing a correlation between a set value of the measuring force application unit and the measuring force;
a measuring force setting unit that sets the measuring force based on the correlation;
A surface texture measuring device comprising: The surface texture measuring device according to claim 1, further comprising a correlation generating unit that generates the correlation according to the measurement conditions when the correlation according to the measurement conditions is not stored. The surface texture measuring device according to claim 1 or 2, wherein the correlation storage unit updates the correlation. The surface texture measuring device according to claim 3, further comprising an update information storage unit that stores update information of the correlation.

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