JP6417691B2 - Dimension measuring apparatus and dimension measuring method - Google Patents

Description

  The present invention relates to a dimension measuring apparatus and a dimension measuring method for measuring a dimension of an object to be measured.

  In general, as a method for measuring the dimension of the object to be measured, a pair of elongated measuring elements parallel to each other are moved relatively on both sides of the object to be measured, and the object to be measured is brought into contact with the tip of the measuring element. It is widely known to detect the distance between the probe at that time. In this method, when the measuring element comes into contact with the object to be measured, the measuring element may be easily bent due to the contact force with the object to be measured, and the dimension may be measured while the measuring element is tilted. For example, when measuring the radial thickness of a ring-shaped object having a long axial length, the measuring element must be longer than the axial length because the measuring element is inserted into the ring of the object to be measured. is there. In that case, the influence of the inclination of the probe on the detection result of the distance becomes large, and it becomes difficult to measure with high accuracy particularly for a large object to be measured.

  Therefore, a measuring element drive unit having a rail extending along the moving direction of the measuring element and a slider movably supported by the rail is provided above the object to be measured, and the measuring element is attached below the slider. A dimension measuring device that minimizes the length of the probe has been proposed (see Patent Document 1). According to this apparatus, the length of the probe can be shortened, and the influence of inclination can be suppressed. However, when the object to be measured is large and it is necessary to insert the measuring element to a deep position of the object to be measured, the measuring element must be lengthened, and the error due to the inclination of the measuring element becomes large.

  Further, in order to measure the absolute value of the dimension of the object to be measured by the linear motion mechanism that linearly moves the probe, it is necessary to move and position the probe with higher accuracy than required. However, in such a linear motion mechanism, there is a positioning error (straightness error in a linear motion guide such as a linear guide and feed error in a feed mechanism such as a ball screw), and these countermeasures are sufficiently considered. The fact is not.

  In addition to the method of contacting the measuring element directly connected to the guide as described above to the object to be measured, the measuring element is supported by a mechanism that can float by an elastic body, thereby suppressing the measuring pressure on the object to be measured. There has been proposed a dimension measuring device that reduces the inclination of (see Patent Document 2).

Japanese Patent Laid-Open No. 10-307018 JP 2007-240339 A

However, since the dimension measuring apparatus of the cited document 2 has a structure in which the measuring element is floated and supported while preventing the play that causes the inclination of the measuring element, the measuring element support structure is disadvantageous. There is. Therefore, it is difficult to increase the degree of freedom of design and to reduce the size.
Accordingly, the present invention is capable of measuring with high accuracy even when measuring a large object to be measured using a long measuring element, and having a structure suitable for downsizing without complicating the apparatus configuration. An object of the present invention is to provide a measuring apparatus and a dimension measuring method.

The present invention has the following configuration.
(1) a mounting table on which a cylindrical object to be measured is mounted;
A measuring element having an arm portion extending toward the mounting table, wherein a contact-type displacement detection unit is disposed at a tip portion of the arm portion;
A linear motion mechanism that supports a base end portion of the arm portion of the probe, moves the probe in a uniaxial direction, and contacts the displacement detector with the object to be measured;
An inclination detection unit that is provided separately from the displacement detection unit and detects an inclination angle formed by an extending direction of the arm part of the probe and an orthogonal plane of the uniaxial direction;
A control unit;
With
The inclination detector detects positions of the uniaxial direction at at least two locations along the extending direction of the probe, respectively, and detects the detected uniaxial positions and the at least two locations of the extending direction. Detecting the tilt angle from the relationship with the position,
The control unit receives the distance detection signal output from the displacement detection unit and the tilt angle detection signal output from the tilt detection unit while the displacement detection unit is in contact with the object to be measured. The displacement detecting unit obtains the amount of displacement in the uniaxial direction caused by the inclination of the arm unit at the arrangement position of the displacement detecting unit in the extending direction, using the tilt angle of the input tilt angle detection signal, and the displacement detector The measurement distance of the distance detection signal output from the correction distance information corrected by the positional deviation amount, from the position of the uniaxial direction of the probe in the tilt angle detection signal and the correction distance information, Outputs the measurement result signal of the object to be measured ,
The displacement detector is an electric micrometer,
The measuring element has a pair arranged in the uniaxial direction with the contact side of the displacement detection unit facing the object to be measured, sandwiching the outer peripheral surface and the inner peripheral surface of the object to be measured, and The two pairs of measuring elements are arranged in two sets along the uniaxial direction,
The linear motion mechanism supports the pair of measuring elements so as to be independently movable in the uniaxial direction,
The control unit is configured to measure the other measurement position at a measurement position at one circumferential direction measured by one pair of the measuring elements and a corresponding position on the opposite side across the center of the object to be measured from the one circumferential direction. Measure the inner diameter and outer diameter of the object to be measured at the same time at the measurement position measured by the pair of children,
Dimension measuring device.
(2) the slope detector, the dimensions described above in a linear scale arranged along the axial direction, a detection head for detecting position information from the linear scale provided on the measuring element, having (1) measuring device.
( 3 ) A dimension measuring method for measuring a dimension of an object to be measured using the dimension measuring apparatus according to (1) or (2) ,
Obtaining the correction distance using a master body having a known dimension as an object to be measured, and setting the correction distance as a first distance;
Measuring the object to be measured as a dimension measurement object to obtain the correction distance, and setting the correction distance as a second distance;
Adding the difference of the second distance to the first distance to a known dimension of the master body to determine the dimension of the object to be measured;
A dimension measuring method including:
( 4 ) The dimension measuring method according to ( 3 ), wherein the mounting table is rotated at a constant angle to obtain a dimension of the object to be measured placed on the mounting table at each rotation position.

  According to the present invention, it is possible to measure with high accuracy even when measuring a large object to be measured using a long measuring element, and to make the structure suitable for miniaturization without complicating the apparatus configuration. it can.

It is a figure for demonstrating embodiment of this invention, and is a whole block diagram of a dimension measuring apparatus. It is a partial block diagram which shows the structure of the X direction linear motion mechanism which moves a measuring element, and the inclination detection part. It is a control block diagram of a dimension measuring device. It is a flowchart which shows the dimension measurement procedure of a workpiece | work. It is explanatory drawing which shows the positional relationship of the electric micrometer, the 1st detection head, and the 2nd detection head in the neutral state where a contact force is not loaded to a measuring element. It is explanatory drawing which shows the positional relationship of the electric micrometer, the 1st detection head, and the 2nd detection head in the state in which the contact force was loaded on the measuring element.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram for explaining an embodiment of the present invention and is an overall configuration diagram of a dimension measuring apparatus.
The dimension measuring apparatus 100 includes a gantry 11, a mounting table 13 on the gantry 11 on which a workpiece W as a measurement object is placed, a pair of measuring elements 15A and 15B, and a pair of measuring elements 17A and 17B. The X direction linear motion mechanism 21 provided on the mounting plate 19, the Z direction linear motion mechanism 25 provided on the frame 23, and the Y direction linear motion mechanism 27 provided on the gantry 11. Moreover, the dimension measuring apparatus 100 is provided with the inclination detection part which measures the inclination angle of each measuring element 15A, 15B, 17A, 17B although the detail is mentioned later.

  The mounting table 13 is directly connected to a rotating shaft (not shown) installed in the gantry 11 and supports the workpiece W in a rotatable manner. For example, if the workpiece W is cylindrical, the workpiece W can be rotated at an arbitrary rotation angle with the center of the cylinder of the workpiece W fixed to the mounting table 13 as the rotation center.

  Each of the pair of measuring elements 15A and 15B and the pair of measuring elements 17A and 17B is connected to the X-direction linear motion mechanism 21 at each base end, and each measuring element is independently movable in the X direction (uniaxial direction). It is supported by. These two pairs of measuring elements have the same structure.

  The X-direction linear motion mechanism 21 includes a ball screw nut portion 31 and a linear guide portion 33. The ball screw nut portion 31 includes a ball screw 35 disposed on the mounting plate 19 along the X direction, a servo motor 37 that rotationally drives the ball screw 35, and nut portions 39A and 39B. The nut part 39A supports the measuring element 15A, and the nut part 39B supports the measuring element 17A. Both of these nut portions 39A and 39B are inserted into the ball screw 35 and moved in the X direction by the rotation of the ball screw 35.

  The linear guide portion 33 includes a guide rail 41 and sliders 43A, 43B, 45A, and 45B that move in the X direction along the guide rail 41. A measuring element 15A is fixed to the slider 43A, and a measuring element 15B is fixed to the slider 43B. In addition, the measuring element 17A is fixed to the slider 45A, and the measuring element 17B is fixed to the slider 45B.

  Here, since the pair of measuring elements 15A and 15B and the pair of measuring elements 17A and 17B have the same configuration, the pair of measuring elements 15A and 15B will be described below as an example.

  FIG. 2 is a partial configuration diagram illustrating an X-direction linear motion mechanism 21 that moves the measuring elements 15A and 15B and an inclination detection unit that will be described in detail later. When the workpiece W has a cylindrical shape, the measuring element 15A functions as a measuring element for measuring the outer diameter, and the measuring element 15B functions as a measuring element for measuring the inner diameter.

  Each measuring element 15A, 15B has long arm portions 47A, 47B extending downward from the X-direction linear motion mechanism 21 side toward the workpiece W. Electric micrometers 49A and 49B serving as displacement detection units for measuring the distance from the workpiece W are disposed at the distal ends of the arms 47A and 47B on the workpiece W side. The contacts 51, 51 of the electric micrometers 49A, 49B are arranged on the contact side with the workpiece W of the arm portions 47A, 47B facing each other.

  The electric micrometers 49 </ b> A and 49 </ b> B are comparative length measuring devices that have a contact-type touch sensor 51 and convert a minute displacement of the touch sensor 51 into an electrical quantity for measurement. The contact 51 is provided so as to protrude from the main body of the electric micrometers 49A and 49B along the distance detection direction, and is elastically biased and supported in the protruding direction. The electric micrometers 49A and 49B output the position of the contact 51 within a predetermined length of detectable stroke as distance information.

  Further, one end of an electric actuator 53 connected to the proximal end portion of the measuring element 15B is connected between the nut portion 39A of the measuring element 15A and the slider 43A. The electric actuator 53 is provided on the measuring element 15B, and moves the measuring element 15B closer to or away from the measuring element 15A along the X direction.

  A first linear scale 55 is disposed on the ball screw 35 side of the guide rail 41 on the mounting plate 19, and a second linear scale 57 is disposed on the workpiece W side. A first detection head 59 is disposed at a position facing the first linear scale 55 of the probe 15A, and a second detection head 61 is disposed at a position facing the second linear scale 57. Yes. In addition, the first detection head 63 is disposed at a position facing the first linear scale 55 of the probe 15B, and the second detection head 65 is disposed at a position facing the second linear scale 57. Yes.

  The first detection head 59 of the probe 15A detects the position of the arm portion 47A in the X direction from the first linear scale 55 facing, and the second detection head 61 detects the arm from the second linear scale 57 facing. The position of the part 47B in the X direction is detected. Similarly, the first detection head 63 of the probe 15B detects the position of the arm portion 47B in the X direction from the first linear scale 55 facing, and the second detection head 65 is the second linear scale facing. 57, the position of the arm portion 47B in the X direction is detected.

  As the linear scale position detection method, an optical method or a magnetic method is preferable. In addition to the linear scale, a laser distance meter or an electric micrometer having a long measurement range may be used. The first linear scale 55, the second linear scale 57, the first detection heads 59, 63, and the second detection heads 61, 63, 65 constitute an inclination detection unit.

  In addition, the first detection head 63 is disposed at a position facing the first linear scale 55 of the probe 15B, and the second detection head 65 is disposed at a position facing the second linear scale 57. ing. The first detection head 63 and the second detection head 65 detect the position of the arm portion 47B in the X direction from the first and second linear scales 55 and 57 facing each other.

  The dimension measuring apparatus 100 configured as described above detects the position of the workpiece W in the X direction while the tip portions of the measuring elements 15A and 15B sandwich the outer circumferential surface 73 and the inner circumferential surface 75 of the workpiece W and are in contact with the workpiece W. At that time, the arm portions 47A and 47B may be bent by the contact force received from the workpiece W by the tip portions of the measuring elements 15A and 15B. When the arm portions 47A and 47B are bent, the output of the electric micrometers 49A and 49B includes a bending error in the X direction position, and the accurate X direction position of the workpiece W cannot be detected.

Therefore, in the measuring element 15A, the inclination angle in the extending direction of the arm portion 47A with respect to the plane orthogonal to the X direction is obtained by the first detection head 59 and the second detection head 61 provided in the arm portion 47A. Then, based on the measured inclination angle, a deviation amount δ _xA in the X direction generated at the position (position in the Z-axis direction) where the electric micrometer 49A at the tip of the arm portion 47A is disposed is obtained. The deviation output signal δ _XA is used to correct the distance output signal from the electric micrometer 49A.

Similarly, for the measuring element 15B, a deviation amount δ _xB in the X direction due to the bending of the arm portion 47B is obtained, and the distance output signal from the electric micrometer 49B is corrected using this deviation amount δ _xB . Thereby, the X direction distance of the workpiece | work W is detectable with high precision irrespective of the inclination of arm part 47A, 47B. The detailed dimension measurement procedure of the workpiece W will be described later.

  In this configuration, electric micrometers 49A and 49B are used as distance detectors, and when the toucher 51 comes into contact with the workpiece W, the toucher 51 is pushed into the electric micrometer along the contact direction. Since this pushing force is generally a minute force, it is possible to prevent the arm portions 47A and 47B from being greatly bent during distance detection. As a result, the deflection of the arm portions 47A and 47B can be accommodated in a light load region where the linearity between the contact force and the arm displacement amount is high, and the generated displacement amount in the X direction can be obtained with high accuracy.

FIG. 3 is a control block diagram of the dimension measuring apparatus 100 configured as described above.
The control unit 71 that performs overall control of the dimension measuring apparatus 100 is configured by a PC (personal computer), a PLC (programmable logic controller), or the like.

  The control unit 71 receives the measurement start signal input to the input unit 77, and each of the ball screw nut unit 31, the electric actuator 53, the Z direction linear motion mechanism 25, and the Y direction linear motion mechanism 27 of the X direction linear motion mechanism 21. A driving signal is output to the measuring elements 15A and 51B to move them to desired positions in the space.

  And the control part 71 makes the contact 51 contact the workpiece | work W, the distance detection signal which the electric micrometer 49A of the measurement element 15A outputs, the 1st detection head 59, and the 2nd detection head 61. And the tilt angle detection signal output from the. Further, the distance detection signal output from the electric micrometer 49B of the probe 15B and the tilt angle detection signal output from the first detection head 63 and the second detection head 65 are captured.

  The control unit 71 obtains the inclination angle of each measuring element 15A, 15B from the acquired inclination angle detection signal, and obtains the amount of deviation in the X direction generated at the tip of each measuring element 51A, 15B according to this inclination angle. And the control part 71 correct | amends the measurement distance obtained by the distance detection signal which electric micrometer 49A, 49B outputs using this deviation | shift amount.

  The corrected distance information is information used for measuring the dimension of the workpiece W, is subjected to a predetermined process, and is output to the output unit 79 as a signal of a dimension measurement result. Although explanation is omitted, the above signals are similarly taken in the measuring elements 17A and 17B, and a signal of a dimension measurement result based on the correction distance information is output to the output unit 79.

  When the average value of the dimension is obtained by performing the measurement a plurality of times, the control unit 71 temporarily stores the dimension measurement result of each time in the storage unit 81, and appropriately calculates the stored dimension measurement result. To do.

  Next, a specific procedure for measuring the dimension of the workpiece W by the dimension measuring apparatus 100 having the above configuration will be described in detail with reference to the flowchart of FIG. Here, the dimension measurement of the workpiece W by the measuring elements 15A and 15B will be described. The dimension measurement of the dimension measuring apparatus 100 is to obtain a relative dimensional difference between a master body (hereinafter referred to as a master work) having a known dimension and the work W, that is, the dimension of the master work and the dimension of the work W. This is done by measuring and calculating the difference between the two.

  The master work has been measured to have a dimension as defined by a precise measuring instrument, and has the same shape as or a shape close to the work W that is the object to be measured. The dimension information of the master work is registered in advance in the storage unit 81 or separately registered before the dimension measurement so that the control unit 71 can refer to it.

  First, the control unit 71 drives the X-direction linear motion mechanism 21, the Z-direction linear motion mechanism 25, and the Y-direction linear motion mechanism 27 shown in FIG. (S11). The operator fixes the master work to the mounting table 13 in this state.

  When the operator completes fixing the master work to the mounting table 13, a master work measurement start signal is input to the input unit 77 by a button pressing signal (not shown) or a signal from an external device. The control unit 71 receives the master work measurement start signal, determines that the master work has been fixed (S2), and starts measuring the dimensions of the master work.

  The control unit 71 drives the X-direction linear motion mechanism 21, the Z-direction linear motion mechanism 25, and the Y-direction linear motion mechanism 27 according to the shape of the master work based on manual operation or a pre-registered algorithm. Each measuring element 15A, 15B is moved close to a desired measurement position (S3). The measurement position is a position where the electric micrometers 49A and 49B of the measuring elements 15A and 15B are in contact with the master work, which is obtained from the dimensions of the master work, and can be obtained by calculation.

  As shown in FIG. 2, the control unit 71 moves the measuring element 15 </ b> A to the outside of the outer surface (the surface corresponding to the outer peripheral surface 73 of the workpiece W in the illustrated example) in the dimension measurement portion of the master workpiece. At this time, the probe 15B is also moved to the inside of the inner side surface (the surface corresponding to the inner peripheral surface 75) in the dimension measurement portion of the master work.

  And the control part 71 drives the ball screw nut part 31, and moves the measuring element 15A to a X direction until the contact 51 of the electric micrometer 49A contacts a master work. Further, the control unit 71 drives the electric actuator 53 to move the measuring element 15B toward the measuring element 15A until the contact 51 of the electric micrometer 49B comes into contact with the master work. The contact operation of each of the touch elements 51 and 51 with the master work may be sequential or simultaneous.

  As a result, the outer peripheral surface and the inner peripheral surface of the master work are sandwiched between the electric micrometers 49A and 49B. The controller 71 detects the distance from the master work (the amount by which the toucher 51 is pushed) by the electric micrometers 49A and 49B with the master work sandwiched at the measurement position. Further, the X-direction absolute position of the first linear scale 55 is read by the first detection heads 59 and 63, and the X-direction absolute position of the second linear scale 57 is read by the second detection heads 61 and 65 (S14). .

  Then, the control unit 71 stores the detected output values from the electric micrometers 49A and 49B and the output values from the first detection heads 59 and 63 and the second detection heads 61 and 65 as reference values. 81 (S15). Each output value at this time becomes an output value corresponding to a reference point (origin) when the workpiece W is measured.

  When the setting of the reference value is completed, the control unit 71 drives the X-direction linear motion mechanism 21, the Z-direction linear motion mechanism 25, and the Y-direction linear motion mechanism 27 to move the measuring elements 15A and 15B to the retracted position again. (S16).

  Next, the operator removes the master work from the mounting table 13, and fixes the workpiece W as the object to be measured to the mounting table 13. When the operator completes the fixing of the workpiece W to the mounting table 13, the workpiece measurement start signal is input to the input unit 77 as described above. When receiving the workpiece measurement start signal, the control unit 71 determines that the workpiece W has been fixed (S17), and starts measuring the dimension of the workpiece W.

  The controller 71 drives the X-direction linear movement mechanism 21, the Z-direction linear movement mechanism 25, and the Y-direction linear movement mechanism 27 in the same manner as the measurement of the master workpiece, and puts the measuring elements 15A and 15B at desired measurement positions. Move (S18). And the control part 71 detects the distance (the amount by which the touch element 51 was pushed in) with the electric micrometer 49A, 49B in the state which the measurement elements 15A and 15B moved to this measurement position. Further, the X-direction absolute position of the first linear scale 55 is read by the first detection heads 59 and 63, and the X-direction absolute position of the second linear scale 57 is read by the second detection heads 61 and 65 (S19). .

  The control unit 71 causes the storage unit 81 to store the detected output values from the electric micrometers 49A and 49B and the output values from the first detection heads 59 and 63 and the second detection heads 61 and 65 ( S20).

  Next, the control unit 71 obtains the inclination angles of the arm portions 47A and 47B of the measuring elements 15A and 51B during the master work measurement and the work W measurement using the detected output values, respectively. A correction value in the X direction corresponding to is obtained (S21). And the control part 71 correct | amends the output value of the detected distance information from electric micrometer 49A, 49B using the calculated | required correction value of the X direction (S22).

Here, a method for obtaining a correction value in the X direction and a basic correction method for distance information will be described.
FIG. 5 is an explanatory diagram showing the positional relationship between the electric micrometer 49A, the first detection head 59, and the second detection head 61 in a neutral state where no contact force is applied to the probe 15A. FIG. 6 shows the contact force applied to the probe 15A. FIG. 6 is an explanatory diagram showing a positional relationship among the electric micrometer 49A, the first detection head 59, and the second detection head 61 in a state where a load is applied.

As shown in FIG. 5, the distance in the Z direction from the first detection head 59 facing the first linear scale to the second detection head 61 facing the second linear scale is L ₁ , the second detection head. 61 and Z-direction distance _{L 2} to the center axis of the electric micrometer 49A of probe 51 from.

Further, the X-direction distance detected by the first detection head 59 (X-direction distance from the linear scale origin to the first detection head 59) is X _s1 , and the X-direction distance detected by the second detection head 61 ( The distance in the X direction from the linear scale origin to the second detection head 61 is _{defined as Xs2} . The arm axis Ax is orthogonal to the X direction, which is the moving direction of the probe 51A.

  When an object to be measured (shown as a workpiece W) comes into contact with the electric micrometer 49A, as shown in FIG. 6, the contact force F from the workpiece W is applied to the tip of the arm portion 47A, and the arm portion 47 is The slider 43A tilts around the center position O. The angle formed by the arm axis Ax in the neutral state of the arm portion 47A and the arm axis Axi in the inclined state is defined as an inclination angle θ.

In the state shown in FIG. 6, the inclination angle θ is expressed by equation (1).
θ = tan ⁻¹ {(X _S2 −X _s1 ) / L ₁ } (1)

A deviation amount δx in the X direction due to the inclination angle θ generated at the position in the Z direction of the electric micrometer 49A is expressed by the following equation (2).
δx = X _S2 + L ₂ · tan θ (2)

That is, when the measuring element 15A is inclined, the output of the electric micrometer 49A is reduced by δx from the detection value to be originally obtained. Therefore, the value obtained by subtracting the deviation amount δx from the output value Xa of the electric micrometer 49A is corrected so as to be the output value from the electric micrometer 49A. That is, the corrected output value Xc obtained by correcting the output value Xa from the electric micrometer 49A is expressed by the equation (3).
Xc = Xa−δx (3)

Next, a specific procedure (S21) for obtaining the deviation amount due to the inclination of the measuring element 15A based on the above-described method for obtaining the X direction correction value and the method for correcting the distance information will be described.
Here, a reference value, which is a measurement result for the master work stored in the storage unit 81 in S15 described above, is defined as follows.
The distance detected by the electric micrometer 49A of the probe 15A is the reference distance D _Da ,
The distance detected by the first detection head 59 of the probe 15A is the inclination reference distance X _Da1 ,
The distance detected by the second detection head 61 of the probe 15A is the inclination reference distance X _Da2 ,
The distance detected by the electric micrometer 49B of the probe 15B is the reference distance D _Db ,
The distance detected by the first detection head 63 of the probe 15B is the inclination reference distance X _Db1 ,
The distance detected by the second detection head 65 of the probe 15B is defined as a tilt reference distance _XDb2 .

Moreover, the measurement result with respect to the workpiece | work W memorize | stored in the memory | storage part 81 by above-mentioned S20 is defined as follows.
The distance detected by the electric micrometer 49A of the probe 15A is the detection distance D _Sa ,
The distance detected by the first detection head 59 of the measuring element 15A is the inclination detection distance _XSa1 ,
The distance detected by the second detection head 61 of the probe 15A is the inclination detection distance X _Sa2 ,
The distance detected by the electric micrometer 49B of the probe 15B is the detection distance D _Sb ,
The distance detected by the first detection head 63 of the probe 15B is the inclination detection distance X _Sb1 ,
The distance detected by the second detection head 65 of the probe 15B is _defined as a tilt detection distance X _Sb2 .

Assuming that the inclination angle of the measuring element 15A at the time of master work measurement is the reference inclination angle θ _Da and the inclination angle of the measuring element 15B is the reference inclination angle θ _Db , the reference inclination angles θ _Da and θ _Db are (4) and (5). It is expressed by a formula.
θ _Da = tan ⁻¹ {(X _Da2 −X _Da1 ) / L ₁ } (4)
θ _Db = tan ⁻¹ {(X _Db2 −X _Db1 ) / L ₁ } (5)

Assuming that the tilt angle of the probe 15A at the time of workpiece W measurement is the detected tilt angle θ _Sa and the tilt angle of the probe 15B is the detected tilt angle θ _Sb , the detected tilt angles θ _Sa and θ _Sb are (6) and (7). It is expressed by a formula.
θ _Sa = tan ⁻¹ {(X _Sa2 −X _Sa1 ) / L ₁ } (6)
θ _Sb = tan ⁻¹ {(X _Sb2 −X _Sb1 ) / L ₁ } (7)

The reference distance D _Da and detection distance D _Sa detected by the electric micrometer 49A of the probe 15A, and the reference distance D _Db and detection distance D _Sb detected by the electric micrometer 49B of the probe 15B are expressed by the following equation (2). As shown, the amount of deviation in the X direction according to the tilt angle is included. Therefore, correction distances obtained by correcting the deviation amount in the X direction are obtained for the reference distance D _Da , the detection distance D _Sa , the reference distance D _Db , and the detection distance D _Sb as shown in the equation (3). The reference distance D _Da , the detection distance D _Sa , the correction distance for the reference distance D _Db , and the detection distance D _Sb are respectively set as a correction reference distance CD _Da , a correction detection distance CD _Sa , a correction reference distance CD _Db , and a correction detection distance CD _Sb. As (8) to (11).

_{CD Da = D Da - (X} Da2 + L 2 · tanθ Da) ··· (8)
_{CD Sa = D Sa - (X} Sa2 + L 2 · tanθ Sa) ··· (9)
_{CD Db = D Db - (X} Db2 + L 2 · tanθ Db) ··· (10)
_{CD Sb = D Sb - (X} Sb2 + L 2 · tanθ Sb) ··· (11)

Next, between the outer peripheral surface 73 and the inner peripheral surface 75 (see FIG. 2) of the workpiece W based on the obtained correction reference distance CD _Da , correction detection distance CD _Sa , correction reference distance CD _Db , and correction detection distance CD _Sb . The distance WL in the radial direction is obtained (S23). When the known distance corresponding to the distance between the outer peripheral surface 73 and the inner peripheral surface 75 in the master work is WL ₀ , the distance WL can be obtained by Expression (12).
_{WL = WL 0 + {(CD} Da - CD Sa) + (CD Db - CD Sb)}
(12)

That is, the first distances CD _Da and CD _Db that are correction distances obtained by measuring a master workpiece having a known dimension, and the second distances CD _Sa and CD _Sb that are correction distances obtained by measuring the workpiece W. (CD _{Da -CD Sa} ) and (CD _{Db -CD Sb} ) are added to the known dimension WL ₀ of the master work, thereby obtaining the dimension WL of the work W.

  When the workpiece W has a cylindrical shape, the accuracy may be insufficient by measuring the distance WL only at one place in the circumferential direction. In that case, using the measuring elements 17A and 17B shown in FIG. 1, the corresponding positions on the opposite side across the center of the workpiece W from the measuring positions of the measuring elements 15A and 15B are simultaneously measured. The measurement accuracy can be improved by averaging the measurement results of these two measurement sites.

  Further, in order to obtain an accurate dimension, the mounting table 13 is rotated by a predetermined angle, different circumferential positions of the workpiece W are measured, and each measurement result is averaged. For example, two circumferential directions orthogonal to each other are measured and the measured values are averaged.

  Furthermore, it is also possible to repeat the measurement at each rotational position of the workpiece W and average the measured values for one rotation of the workpiece W obtained thereby.

  According to the dimension measuring apparatus 100 of this configuration, it is also possible to continuously measure the diameter of the workpiece W while rotating the workpiece W. In that case, the diameter of the workpiece W can be obtained with high accuracy by measuring the dimension in the radial direction at a pitch of 1 °, for example, and obtaining the average value of the obtained measured values.

  As described above, the dimension measuring apparatus 100 of this configuration is obtained by measuring the inclination angle due to the deflection of the probe even when measuring a large object to be measured with a long probe. The dimension measurement result is corrected according to the inclination angle. For this reason, even when the measuring element is bent, the workpiece dimensions can be measured with high accuracy without complicating the structure of the dimension measuring apparatus.

  Further, in this configuration, by directly disposing the electric micrometer at the tip of the measuring element, it is not necessary to separately provide a mechanism for elastically supporting the measuring element, and the structure of the apparatus can be simplified. Further, by using a small electric micrometer, the measurement pressure at the time of dimension measurement becomes extremely small, and the inclination caused by the deflection of the probe can be minimized. Furthermore, since the position and orientation of the probe are detected using a plurality of linear scales, each member of the linear scale can be arranged without worrying about interference with other members. Therefore, the size measuring device can be easily miniaturized, and the degree of freedom in design can be increased.

  Moreover, the dimension measuring apparatus 100 of this structure is calculating | requiring the dimension of the workpiece | work W by the comparison with a master workpiece | work. Therefore, even when the object to be measured is affected by thermal expansion or contraction due to the environmental temperature, the dimensional error can be made smaller than the method of measuring the absolute dimension. That is, if the master work and the work W are placed under the same environmental temperature, if the master work is the same material and shape as the work W, thermal expansion and contraction should occur to the same extent. By comparing the relative dimensions of these, high-precision measurement independent of temperature becomes possible.

  As described above, the present invention is not limited to the above-described embodiments, and those skilled in the art can make changes and applications based on combinations of the configurations of the embodiments, descriptions in the specification, and well-known techniques. This is also the scope of the present invention, and is included in the scope for which protection is sought.

  For example, in the configuration of the dimension measuring apparatus 100, a linear scale is used as the tilt detection unit. However, the present invention is not limited to this, and another type of angle sensor such as a tilt sensor using a MEMS element may be used. In addition, the position information of a plurality of locations may be detected in addition to the two locations in the extending direction of the probe. In that case, the measurement accuracy of the tilt angle can be further improved.

  Further, the extending direction of the measuring element is not limited to the vertical direction, and may be configured to extend in the horizontal direction or an arbitrary inclination angle.

  Moreover, in this dimension measuring apparatus 100, although the dimension of the workpiece | work W is calculated | required with a pair of measuring element, the structure measured only with a single measuring element may be sufficient. In that case, a configuration may be adopted in which one end portion of the workpiece W is brought into contact with the abutting portion and the other end portion is detected with a measuring element. With this configuration, the dimensional difference between the master workpiece and the workpiece W can be measured with a single measuring element, and the dimensional measurement can be performed more easily.

13 Mounting base 15A, 15B, 17A, 17B Measuring element 21 X direction linear motion mechanism 31 Ball screw nut part (linear motion mechanism)
33 Linear guide part 41 Guide rail 43A, 43B, 45A, 45B Slider 47A, 47B Arm part 49A, 49B Electric micrometer (displacement detection part)
51 Tactile 53 Electric Actuator 55 First Linear Scale (Tilt Detection Unit)
57 Second linear scale (tilt detector)
59, 63 First detection head (tilt detection unit)
61, 65 Second detection head (tilt detection unit)
71 Control Unit 100 Dimension Measurement Device W Workpiece

Claims (4)

A mounting table on which a cylindrical object to be measured is mounted;
A measuring element having an arm portion extending toward the mounting table, wherein a contact-type displacement detection unit is disposed at a tip portion of the arm portion;
A linear motion mechanism that supports a base end portion of the arm portion of the probe, moves the probe in a uniaxial direction, and contacts the displacement detector with the object to be measured;
An inclination detection unit that is provided separately from the displacement detection unit and detects an inclination angle formed by an extending direction of the arm part of the probe and an orthogonal plane of the uniaxial direction;
A control unit;
With
The inclination detector detects positions of the uniaxial direction at at least two locations along the extending direction of the probe, respectively, and detects the detected uniaxial positions and the at least two locations of the extending direction. Detecting the tilt angle from the relationship with the position,
The control unit receives the distance detection signal output from the displacement detection unit and the tilt angle detection signal output from the tilt detection unit while the displacement detection unit is in contact with the object to be measured. The displacement detecting unit obtains the amount of displacement in the uniaxial direction caused by the inclination of the arm unit at the arrangement position of the displacement detecting unit in the extending direction, using the tilt angle of the input tilt angle detection signal, and the displacement detector The measurement distance of the distance detection signal output from the correction distance information corrected by the positional deviation amount, from the position of the uniaxial direction of the probe in the tilt angle detection signal and the correction distance information, Outputs the measurement result signal of the object to be measured ,
The displacement detector is an electric micrometer,
The measuring element has a pair arranged in the uniaxial direction with the contact side of the displacement detection unit facing the object to be measured, sandwiching the outer peripheral surface and the inner peripheral surface of the object to be measured, and The two pairs of measuring elements are arranged in two sets along the uniaxial direction,
The linear motion mechanism supports the pair of measuring elements so as to be independently movable in the uniaxial direction,
The control unit is configured to measure the other measurement position at a measurement position at one circumferential direction measured by one pair of the measuring elements and a corresponding position on the opposite side across the center of the object to be measured from the one circumferential direction. Measure the inner diameter and outer diameter of the object to be measured at the same time at the measurement position measured by the pair of children,
Dimension measuring device. The dimension measuring apparatus according to claim 1 , wherein the inclination detecting unit includes a linear scale arranged along the uniaxial direction, and a detection head that is provided in the measuring element and detects position information from the linear scale. A dimension measuring method for measuring a dimension of an object to be measured using the dimension measuring apparatus according to claim 1 or 2 ,
Obtaining the correction distance using a master body having a known dimension as an object to be measured, and setting the correction distance as a first distance;
Measuring the object to be measured as a dimension measurement object to obtain the correction distance, and setting the correction distance as a second distance;
Adding the difference of the second distance to the first distance to a known dimension of the master body to determine the dimension of the object to be measured;
A dimension measuring method including: The dimension measuring method according to claim 3 , wherein the mounting table is rotated at a predetermined angle to obtain a dimension of the object to be measured placed on the mounting table at each rotation position.

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