JP2014081333A - Female thread shape measurement device and using method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a female thread shape measurement device and a using method of the female thread shape measurement device that can simply and accurately measure a female thread shape in a short time.SOLUTION: The female thread shape measurement device includes: a support unit; a sensor unit; and a drive unit. The support unit includes a support block having a through-hole through which a tube is inserted and at least three leg assemblies to be arranged in a radial form around the support block with the through-hole as a center. Each of the leg assemblies has, in a radial direction of the through-hole,: a leg case that has an opening at an edge on an opposite side of the support block; a leg member that has a part housed in the leg case, and protrudes advanceably and retractably in the radial direction of the through-hole from the opening of the leg case; an energization member that energizes the leg member toward an outer side in the radial direction of the through-hole; a position adjustment mechanism that adjusts a position of the leg member with respect to the leg case; and a positioning member for releasably determining the position of the leg member with respect to the leg case.

Description

  The present disclosure relates to a female thread shape measuring apparatus and a method of using the apparatus.

The thread of the female screw is deformed or damaged by meshing with the bolt. For this reason, measuring and inspecting the shape of a female screw is performed.
For example, a female screw measuring device disclosed in Patent Document 1 has a sensor holder provided with an overcurrent sensor or the like, and the sensor holder is attached to a spindle end of an NC machine tool via a shank. The workpiece having the screw hole is arranged at a predetermined position on the workpiece table.

  The NC machine tool control unit is given data on the height, depth and horizontal position of the upper end of the screw hole of the workpiece. By moving the spindle end of the NC machine tool, the sensor holder is inserted into the female screw of the workpiece. can do. Thereafter, distance measurement is performed by a distance sensor provided in the sensor holder.

Japanese Patent No. 2903826

In the female screw measuring device disclosed in Patent Document 1, data on the upper end height, depth and horizontal position of the screw hole of the work must be given in advance to the control device of the NC machine tool, and the measurement work is complicated. ,take time.
Further, in the female screw measuring device disclosed in Patent Document 1, the sensor holder is supported by the NC machine tool, and measurement cannot be performed when a workpiece having a screw hole cannot be transported to the NC machine tool. .

  Therefore, at least one embodiment of the present invention aims to provide an internal thread shape measuring apparatus capable of measuring the internal thread shape easily, accurately and in a short time, and a method of using the apparatus.

  According to at least one embodiment of the present invention, a support unit, a sensor unit having an axis, and supported by the support unit so as to be slidable along the axis, and the sensor unit are slid relative to the support unit. In the internal thread shape measuring device including the drive unit to be moved, the sensor unit emits laser light into the tube along the axis and receives reflected light of the laser light along the axis. And a laser displacement meter capable of measuring the distance to the reflection position of the laser beam using the received reflected light, and a mirror that bends the optical path of the laser beam at a right angle with respect to the axis. The unit includes a support block having a through-hole through which the tube is inserted, and a radial shape around the support block around the through-hole. At least three leg assemblies arranged, each leg assembly having a leg case having an opening at an end opposite to the support block in the radial direction of the through hole, and one leg assembly. A leg member that is housed and protrudes from the opening of the leg case so as to advance and retreat in the radial direction of the through hole, and a biasing member that biases the leg member toward the radial outer side of the through hole, An internal thread shape measuring apparatus comprising: a position adjusting mechanism for adjusting a position of the leg member with respect to a leg case; and a positioning member for determining the position of the leg member with respect to the leg case so as to be releasable. Provided.

According to the female thread shape measuring apparatus of the embodiment described above, alignment can be accurately performed by adjusting the protruding amount of the leg member. That is, the axis of the sensor unit can be made to exactly match the axis of the female screw. Thereby, a laser beam can be irradiated to a measurement position along the radial direction from the center of the female screw, and the female screw shape can be accurately measured.
On the other hand, according to this female screw shape measuring apparatus, the NC machine tool is not used for position control of the sensor unit, and the female screw shape can be measured easily and in a short time.

  According to at least one embodiment of the present invention, there is provided a method of using the female thread shape measuring device, wherein the at least three leg assemblies are placed inside the female thread to be measured in a state where the determination by the positioning member is released. A temporary installation step of disposing, a radial distance measuring step of measuring a distance to at least three circumferential positions on an inner peripheral surface of the female screw corresponding to the leg assembly, using the laser displacement meter; and the diameter A method of using the female screw shape measuring device, comprising: a centering step of aligning the axis of the sensor unit with the axis of the female screw using the adjusting mechanism based on the distance measured in the direction distance measuring step. Is provided.

In one embodiment, the position adjusting mechanism includes a rack provided on the leg member and a pinion that meshes with the rack.
According to this configuration, the position of the leg member relative to the leg case can be adjusted with a simple configuration.

In one embodiment, the biasing member comprises a compression coil spring, and the positioning member comprises a screw.
According to this configuration, since the positioning member is formed of a screw, the position of the leg member relative to the leg case can be determined to be releasable with a simple configuration.
According to this configuration, in a state where the positioning by the positioning member is released and the leg member is free, the leg member can elastically contact the inner peripheral surface of the female screw to be measured. For this reason, the support unit can be easily fixed to the female screw.

  According to the method for using the female thread shape measuring apparatus of the embodiment described above, the alignment process is performed after fixing the female thread shape measuring apparatus to the female thread in the temporary installation process, so that the adjustment can be performed easily and in a short time. Can do the heart.

  According to at least one embodiment of the present invention, an internal thread shape measuring apparatus capable of measuring the internal thread shape easily, accurately and in a short time and a method of using the apparatus are provided.

It is a figure showing the schematic structure of the internal thread shape measurement system concerning one embodiment of the present invention. It is a figure which shows schematic structure of the internal thread shape measuring apparatus in FIG. It is a schematic diagram for demonstrating the structure of the support unit in FIG. It is a schematic diagram for demonstrating the structure of the support unit in FIG. It is a schematic flowchart for demonstrating the procedure of the installation method of the internal thread shape measuring apparatus of FIG. It is a figure which shows schematically the structure of the modification of the leg assembly applied to the internal thread shape measuring apparatus of FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Only.

  FIG. 1 shows a schematic configuration of an internal thread shape measurement system according to an embodiment of the present invention. The internal thread shape measurement system includes an internal thread shape measurement device 10 and a measurement control device 12. The female thread shape measuring apparatus 10 has a support unit 14 and an axis 16, and is supported by the support unit 14 so as to be slidable along the axis 16, and the sensor unit 18 is slid relative to the support unit 14. Drive unit 20 to be operated.

The sensor unit 18 includes, for example, a box-shaped sensor case 22, a cylindrical tube 24 that integrally extends from the sensor case 22 and defines the axis 16, a laser displacement meter 26 disposed in the sensor case 22, and a tube 24. And a mirror 28 arranged inside.
The laser displacement meter 26 has a function of measuring the distance between the laser displacement meter 26 and the measurement position. Specifically, the laser displacement meter 26 emits laser light (probe light) toward the measurement position, and receives a reflected component (reflected light) of the laser light reflected at the measurement position. The laser displacement meter 26 outputs a signal corresponding to the distance from the laser displacement meter 26 to the measurement position based on the received reflected light.

  The laser displacement meter 26 is disposed in the sensor case 22 so as to emit probe light along the axis 16. The mirror 28 is disposed at an angle of 45 ° with respect to the axis 16 in the end of the tube 24 opposite to the sensor case 22.

  The optical path L of the probe light is bent by the mirror 28 so as to be orthogonal to the axis 16, and the probe light propagates from the mirror 28 toward the radially outer side of the tube 24. The tube 24 is provided with a translucent portion for allowing the probe light to pass therethrough, and the probe light propagates toward the radially outer side of the tube 24 through the translucent portion. That is, a part of the optical path L through which the laser light emitted from the laser displacement meter 26 propagates is defined inside the tube 24.

  Here, when measuring the shape of the female screw to be measured, the axis 16 is made to coincide with the axis of the female screw. Therefore, the probe light that has passed through the translucent portion is incident on the inner peripheral surface of the female screw along the radial direction of the female screw. The reflected light generated by reflecting the probe light at the measurement position propagates in the opposite direction along the optical path L through which the probe light has propagated, and enters the laser displacement meter 26.

  The drive unit 20 has a function of moving the sensor unit 18 slidably supported by the support unit 14 in the direction of the axis 16. The drive unit 20 is composed of, for example, a cylinder type linear actuator, and includes a cylinder 30 and a rod 32 that protrudes forward and backward from the cylinder 30. The sensor case 22 is fixed to the tip of the rod 32 in a state where the forward / backward direction of the rod 32 coincides with the direction of the axis 16 of the tube 24.

The measurement control device 12 is configured by a computer, for example, and includes a CPU (Central Processing Unit), a memory, an external storage device, an input / output device, and the like. The measurement control device 12 is electrically connected to the laser displacement meter 26 and the drive unit 20 and controls the laser displacement meter 26 and the drive unit 20. On the other hand, the measurement result of the laser displacement meter 26 is input to the measurement control device 12.
The drive unit 20 has a built-in position detector such as an encoder, and the measurement control device 12 can grasp the measurement position in the direction of the axis 16.

Specifically, the measurement control device 12 moves the sensor unit 18 in the direction of the axis 16 continuously or intermittently by the drive unit 20, and thereby the measurement position on the inner peripheral surface of the female screw at an appropriate interval. While changing, the laser displacement meter 26 is caused to measure the distance to each measurement position. Thereby, the distance from the radial center of the internal thread to each measurement position can be obtained, and the surface shape of the thread of the internal thread can be measured.
In the present embodiment, the measurement control device 12 stores the reference shape of the female screw to be measured, and the measurement control device 12 can simultaneously display and compare the measured shape and the reference shape.

The support unit 14 is fixed relative to the female screw during measurement, and supports the sensor unit 18 so as to be movable in the direction of the axis 16 of the tube 24.
Specifically, the support unit 14 includes a support block 34, a guide tube 36, and at least three leg assemblies 38.

The support block 34 has a substantially cylindrical shape and has a through hole 40. A cylindrical guide tube 36 is inserted and fixed in the through hole 40. The tube 24 of the sensor unit 18 is slidably inserted into the guide cylinder 36, and the sensor unit 18 driven by the drive unit 20 is guided by the guide cylinder 36.
In the present embodiment, the drive unit 20 is fixed to the support block 34 via a bracket.

  FIG. 2 is a plan view schematically showing a state in which the female screw shape measuring apparatus 10 is fixed to the female screw to be measured, excluding the drive unit 20. With reference to FIGS. 1 and 2, at least three leg assemblies 38 are radially disposed about the support block 34 about the axis 16. In the present embodiment, the three leg assemblies 38 are arranged at intervals of 120 °.

3 and 4 are partial cutaway views schematically showing the configuration of each leg assembly 38. FIG. As shown in FIGS. 3 and 4, each leg assembly 38 includes a leg case 42, a leg member 44, a biasing member 46, a position adjusting mechanism 48, and a positioning member 50.
The leg case 42 is provided integrally with the support block 34, has a box shape, and extends in the radial direction of the through hole 40 perpendicular to the axis 16. Each leg case 42 is open at the end opposite to the support block 34.

The leg member 44 has a substantially rectangular parallelepiped shape, and the base end side of the leg member 44 is slidably accommodated in the leg case 42. The distal end side of the leg member 44 protrudes from the opening of the leg case 42.
The urging member 46 is made of, for example, a compression coil spring, and is disposed between the base end of the leg member 44 and the inner end surface of the leg case 42 in the leg case 42. In this embodiment, two compression coil springs are arranged in parallel as the biasing member 46. The urging member 46 urges the leg member 44 in a direction in which the leg member 44 protrudes from the opening of the leg case 42, that is, toward the radially outer side of the through hole 40.

  Due to the urging force of the urging member 46, the tip of the leg member 44 can elastically contact the inner peripheral surface of the female screw to be measured. In the present embodiment, a protrusion 51 that protrudes outward in the radial direction of the through hole 40 is provided at the tip of the leg member 44. The protrusion 51 has a shape that can mesh with the thread groove of the internal thread, and the protrusion 51 elastically meshes with the thread groove of the internal thread by the urging force of the urging member 46.

  The position adjusting mechanism 48 is for adjusting the protruding amount of the leg member 44 from the leg case 42 by adjusting the relative position of the leg member 44 with respect to the leg case 42. By adjusting the protruding amounts of the three leg members 44, the axis 16 can be aligned with the axis of the female screw to be measured (alignment).

  The position adjustment mechanism 48 is configured by a tooth row composed of a plurality of gears, and specifically includes a rack 52, a pinion 54, and a rotation knob 56. The rack 52 is integrally provided on one side surface of the leg member 44. The rack 52 extends in the radial direction of the through hole 40, in other words, in the sliding direction of the leg member 44.

The pinion 54 has an intermediate gear 58 and an output gear 60, and the intermediate gear 58 and the output gear 60 are connected coaxially. The pinion 54 is rotatably supported by the leg case 42 in a state where the output gear 60 is engaged with the rack 52.
The rotary knob 56 has a knob body 62 and an input gear 64, and the knob body 62 and the input gear 64 are connected coaxially. The rotation knob 56 is rotatably supported by the leg case 42 with the input gear 64 meshed with the intermediate gear 58 of the pinion 54.

  When the knob main body 62 of the rotary knob 56 is turned, the input gear 64, the intermediate gear 58, and the output gear 60 are rotated, whereby the leg member 44 moves together with the rack 52 that meshes with the output gear 60. Therefore, the protruding amount of the leg member 44 from the leg case 42, in other words, the length of the leg assembly 38 in the radial direction of the through hole 40 can be adjusted by the rotating direction and rotating amount of the knob body 62.

  In the present embodiment, the positioning member 50 is a screw, and the positioning member 50 can contact the side surface of the leg member 44 through a screw hole provided in the side wall of the leg case 42. In a state where the amount of protrusion of the leg member 44 is adjusted by operating the rotary knob 56, the screw as the positioning member 50 is screwed and the leg member 44 is pressed against the side wall on the opposite side of the leg case 42. Can be fixed.

Hereinafter, the usage method of the internal thread shape measuring apparatus 10 is demonstrated centering on the installation method. FIG. 5 is a flowchart schematically showing the procedure of the installation method.
First, in the temporary installation step S10, the leg assembly 38 is placed in the female screw to be measured so as to be radially arranged in a state where the fixing of the leg member 44 by the positioning member 50 is released. In this state, the leg member 44 can be retracted toward the radially inner side of the through hole 40 against the urging force of the compression coil spring. Therefore, even if the leg member 44 protrudes from the opening of the leg case 42, the three leg assemblies 38 can be inserted into the internal thread.

When the leg case 42 is disposed in the female screw, the leg member 44 elastically contacts the inner peripheral surface of the female screw by the biasing force of the compression coil spring. Thus, the leg member 44 elastically contacts the inner peripheral surface of the female screw, so that the female screw shape measuring device 10 is temporarily installed around the female screw.
In the temporary installation step S10, the female screw shape measuring device 10 is rotated with respect to the female screw in a state where the leg member 44 elastically contacts the inner peripheral surface of the female screw. Thereby, the thread groove of the female screw and the protrusion 51 of the leg member 44 are reliably engaged with each other. Then, the leg member 44 is temporarily fixed by the positioning member 50 in a state where the thread groove and the protrusion 51 are engaged with each other.

  Thereafter, the meshing confirmation step S12 is performed. In the meshing step S12, it is confirmed whether or not the thread groove of the female screw and the projection 51 of the leg member 44 are meshed with each other. As a result of the confirmation, if it is not meshed, the temporary installation step S10 is executed once more, and the female thread shape measuring device 10 is rotated with respect to the female thread. As a result of the confirmation, if it is meshed, the alignment measurement positioning step S14 is executed.

  In the alignment position measurement step S14 for alignment, a measurement position for distance measurement by the laser displacement meter 26 performed for alignment is determined. That is, after selecting an appropriate measurement position, the drive unit 20 is driven, the position of the sensor unit 18 is adjusted in the direction of the axis 16, and the translucent portion of the tube 24 is opposed to the measurement position.

When the alignment measurement position selected in the alignment measurement position alignment step S14 is a region where no thread exists on the inner peripheral surface of the female screw, the three-radial distance measurement step S16 is executed. In the three radial direction distance measuring step S16, distance measurement by the laser displacement meter 26 is sequentially performed at three circumferential positions corresponding to the circumferential position of the leg member 44.
Note that the sensor unit 18 is rotatable with respect to the support unit 14 in order to measure at three circumferential positions.

  In the present embodiment, the guide tube 36 is provided with a light transmitting portion 66 for alignment at three positions corresponding to the circumferential position of the leg assembly 38 at two positions in the direction of the axis 16. It has been. An appropriate one of the light transmitting portions 66 of the guide cylinder 36 can be used to perform distance measurement for alignment. However, without using the light transmitting portion 66 of the guide tube 36, the end of the tube 24 provided with the light transmitting portion is projected from the end of the guide tube 36, and distance measurement for alignment is performed. Also good.

  When the measurement position selected in the alignment measurement position alignment step S14 is a region where a thread exists on the inner peripheral surface of the female screw, the three-diameter direction screw bottom distance measurement step S18 is executed. In the three-diameter direction screw bottom distance measurement step S18, distance measurement by the laser displacement meter 26 is sequentially performed at three circumferential positions corresponding to the circumferential position of the leg member 44.

  However, since there is a screw thread, the position of the sensor unit 18 is adjusted in the direction of the axis 16 so that the measurement position coincides with the screw bottom (valley bottom) for each measurement at three circumferential positions. In this adjustment, the distance measurement is repeated while changing the position in the direction of the axis 16, and the position where the measured distance is the maximum is set as the measurement position. That is, the maximum distance among the distances measured while changing the position in the direction of the axis 16 at each circumferential position is selected as the radial distance.

  After the three radial direction distance measuring step S16 or the three radial direction screw bottom distance measuring step S18, it is determined whether the distances r1, r2, r3 to the three measurement positions are substantially equal to each other (alignment determining step) S20). If the three distances r1, r2, and r3 are substantially equal to each other as a result of the alignment determination step S20, the installation of the female thread shape measuring apparatus 10 is completed.

  On the other hand, if the three distances r1, r2, and r3 are not substantially equal to each other as a result of the alignment determination step S20, a leg member protrusion amount adjustment step (alignment step) S22 is executed. In the leg member protrusion amount adjusting step S22, the fixing of the leg member 44 by the positioning member 50 is released, and the position adjustment mechanism 48 is used to protrude the leg member 44 so that the three distances r1, r2, and r3 are equal. Adjust the amount. After the adjustment, the leg member 44 is fixed by the positioning member 50 again.

After the leg member protrusion amount adjusting step S22, the three radial direction distance measuring step S16 or the three radial direction screw bottom distance measuring step S18 is executed again. Thereafter, the alignment determination step S20 is executed, and the alignment step S22 is repeated until the three distances r1, r2, r3 are equal to each other.
When the three distances r1, r2, and r3 are substantially equal, in addition to the case where the three distances r1, r2, and r3 are equal, the difference between the three distances r1, r2, and r3 is necessary for measuring the female screw shape. The case where it is negligible when considering the accuracy is also included.

Thus, when the female thread shape measuring apparatus 10 is installed, the female thread shape measurement is executed. In the internal thread shape measurement, the distance to the measurement position is measured while changing the measurement position in the direction of the axis 16 at one circumferential position of the internal thread.
The measurement result represents the surface shape of the inner peripheral surface of the female screw, and is a combination of the measurement position and distance in the direction of the axis 16. By comparing the obtained measurement result with the reference shape of the internal thread, it is possible to grasp the deformation and wear state of the thread of the internal thread. In addition, you may measure a shape in several circumferential direction position with respect to one internal thread.

According to the female thread shape measuring apparatus 10 of the above-described embodiment, the alignment can be accurately performed by adjusting the protruding amount of the leg member 44. In other words, the axis 16 of the sensor unit 18 can be accurately matched with the axis of the female screw. Thereby, a laser beam can be irradiated to a measurement position along the radial direction from the center of the female screw, and the female screw shape can be accurately measured.
On the other hand, according to this female thread shape measuring apparatus 10, an NC machine tool is not used for position control of the sensor unit 18, and the female thread shape can be measured easily and in a short time.

  Further, in the female thread shape measuring apparatus 10 of the above-described embodiment, the position adjusting mechanism 48 includes a rack 52 provided on the leg member 44 and a pinion 54 that meshes with the rack 52. The position of the leg member 44 relative to 42 can be adjusted.

Furthermore, according to the female thread shape measuring apparatus 10 of the above-described embodiment, since the positioning member 50 is formed of a screw, the position of the leg member 44 relative to the leg case 42 can be determined to be releasable with a simple configuration. .
Furthermore, according to the female thread shape measuring apparatus 10 of the above-described embodiment, the biasing member 46 is formed of a compression coil spring, and when the positioning by the positioning member 50 is released and the leg member 44 is free, the measurement target is measured. The leg member 44 can elastically contact the inner peripheral surface of the female screw. For this reason, the support unit 14 can be easily fixed to the female screw to be measured.

  On the other hand, the internal thread shape measurement system of the above-described embodiment is easier to carry than an NC machine tool, and can measure the internal thread shape without moving the member having the internal thread to be measured from the site. For this reason, the female thread shape measurement system of the above-described embodiment is suitable for measuring the shape of the female thread of a member constituting a housing or the like of a large machine installed in a power plant or the like, but the application target is limited to this. There is nothing.

  According to the installation method of the female thread shape measuring device of one embodiment described above, after fixing the female thread shape measuring device 10 to the female screw in the temporary installation step S10, the leg member protrusion amount adjusting step (alignment step) S22 is performed. By performing, alignment can be performed easily and in a short time.

  In the installation method of the female thread shape measuring apparatus according to the embodiment described above, the thread bottom is selected as the measuring position for alignment. The height of the screw thread may change due to wear, etc., but the depth of the screw bottom is unlikely to change, and by selecting the screw bottom as the measuring position for alignment, it is possible to accurately Can be aligned.

The present invention is not limited to the above-described embodiment, and includes a form obtained by modifying the above-described embodiment.
For example, the configuration of the dentition of the position adjustment mechanism 48 is not particularly limited. FIG. 6 schematically shows a modified leg assembly 68, and as shown in FIG. 6, the position adjusting mechanism 48 includes two racks 52 that are integrally provided on opposite side surfaces of the leg member 44. , 52 may be included. In this case, a reverse gear 70 is interposed between the one pinion 54 and the input gear 64 so that the rotation directions of the two pinions 54 and 54 are opposite to each other.

  Moreover, although the internal thread shape measuring apparatus 10 of one Embodiment mentioned above was used for the measurement of internal thread shape, it is applicable also to the internal diameter measurement of the hole in which the thread groove is not formed. In this case, since there is no thread groove on the inner peripheral surface of the hole, the protrusion 51 does not have to be provided at the tip of the leg member 44.

DESCRIPTION OF SYMBOLS 10 Female thread shape measuring device 12 Measurement control device 14 Support unit 16 Axis 18 Sensor unit 20 Drive unit 24 Tube 26 Laser displacement meter 28 Mirror 38 Leg assembly 40 Through-hole 42 Leg case 44 Leg member 46 Biasing member 48 Position adjustment mechanism 50 Positioning Element

Claims (4)

A support unit;
A sensor unit having an axis and supported by the support unit so as to be slidable along the axis;
In an internal thread shape measuring device comprising a drive unit that slides the sensor unit relative to the support unit,
The sensor unit is
A tube defining the axis;
Laser displacement that emits laser light into the tube along the axis, receives reflected light of the laser light, and measures the distance to the reflected position of the laser light using the received reflected light Total
A mirror that bends the optical path of the laser light at right angles to the axis,
The support unit is
A support block having a through hole through which the tube is inserted;
And at least three leg assemblies arranged radially around the through-hole around the support block;
Each of the leg assemblies includes
A leg case having an opening at the end opposite to the support block in the radial direction of the through hole;
A leg member that is partly accommodated in the leg case and protrudes from the opening of the leg case so as to advance and retreat in the radial direction of the through hole;
A biasing member that biases the leg member toward the radially outer side of the through hole;
A position adjusting mechanism for adjusting the position of the leg member with respect to the leg case;
A female thread shape measuring apparatus comprising: a positioning member for releasably determining the position of the leg member with respect to the leg case. The position adjustment mechanism is
A rack provided on the leg member;
The female thread shape measuring apparatus according to claim 1, further comprising a pinion that meshes with the rack. The biasing member comprises a compression coil spring,
3. The female thread shape measuring device according to claim 2, wherein the positioning member is a screw. It is a usage method of the internal thread shape measuring apparatus of Claim 1,
A temporary installation step of disposing the at least three leg assemblies inside the female screw to be measured in a state where the determination by the positioning member is released;
A radial distance measuring step of measuring a distance to at least three circumferential positions on an inner circumferential surface of the female screw corresponding to the leg assembly using the laser displacement meter;
An internal thread shape measuring device comprising: an alignment step of aligning the axis of the sensor unit with the axis of the internal thread using the adjustment mechanism based on the distance measured in the radial distance measuring step how to use.

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