JP7068567B2 - Optimal hole diameter measuring method and optimum hole diameter measuring device - Google Patents

Description

In the present invention, a reference hole and an annular trepanning hole are formed concentrically outside the reference hole in a measurement object such as a welded structure, and the shape change of the reference hole is measured to measure the residual stress on the surface and inside of the measurement object. The present invention relates to an optimum hole diameter measuring method capable of measuring the hole diameter of a reference hole with high accuracy and easily using an air micrometer, and an optimum hole diameter measuring device using the same method (MIRS method).

Conventionally, the residual stress evaluation method by the deep hole drilling method (DHD) measures the hole diameter before and after stress release by four procedures as shown in FIG. 7, and the residual stress value inside the plate thickness is measured from the amount of change in the hole diameter. Is calculated. First, a front bush is attached to the drilled part of the object to be measured, and a through or non-penetrating hole is drilled using a gun drill (Reference hole (hereinafter referred to as "reference hole")). ) (See Step 1 in FIG. 7 (a)). Next, with respect to this reference hole, the hole diameter is measured at one or more points in the hole depth direction and at three or more points in the circumferential direction (see Step 2 in FIG. 7 (b)). Next, the reference hole is coaxially hollowed out in a cylindrical shape (trepanning) to release the restraint around it and release the residual stress (see Step 3 in FIG. 7 (c)). .. Then, the hole diameter is measured again at one or more points in the hole depth direction and at three or more points in the circumferential direction with respect to the reference hole after the peripheral removal by the trepanning process (see Step 4 in FIG. 7 (d)). From these measured values, the in-plane stress components (σx, σy, σxy) with respect to the pore diameter can be calculated on the assumption that the material is an elastic material, the pores are in an infinite flat plate, and the plane stress state.

Further, in order to eliminate the influence of plastic deformation that occurs in the stress release process in which the trepanning process is performed coaxially in a cylindrical shape, the trepanning process and the hole diameter measurement are sequentially performed by the sequential deep hole drilling method (iDHD method: incremental deep hole drilling). The hole axial component (σz) that can be calculated by the above-mentioned deep hole drilling method can also be calculated.

Further, in the DHD method and the iDHD method, the influence of the three-dimensional stress state and the plastic deformation on the pore diameter due to the above assumption conditions is not taken into consideration, and there is a problem that the actual value and the theoretical value deviate from each other. Since the accuracy of in-plane stress (residual stress (σx, σy, σxy)) drops, the DHD method and iDHD method (hereinafter, also simply referred to as “DHD method”) are practical measurement methods for residual stress measurement methods. It wasn't widespread. On the other hand, the applicant has made a high-precision plate thickness internal residual stress measurement method that can consider the effects of three-dimensional stress state and plastic deformation by bringing the assumption conditions closer to the actual phenomenon. Improved deep hole drilling method (hereinafter, "MIRS"). (Referred to as "law") is provided in Patent Document 2 (details will be described later).

In any of the above DHD method, iDHD method or MIRS method (hereinafter referred to as "MIRS method"), a method using a mechanical / electric micrometer as a contact type measurement or a non-method for measuring the hole diameter of the reference hole is performed. As a contact type measurement, a method using an air micrometer using an air probe can be considered. Of these, an air micrometer (air micrometer) is a comparative measuring instrument that measures the dimensions of an object by the flow rate of air, and there are measurement methods such as a flow rate type and a back pressure type. In the case of the flow rate type, which is specifically used when measuring the reference hole, first create clean compressed air with a compressor and filter, then keep this at a constant pressure with a regulator, and then insert the nozzle of the air probe into the reference hole. Compressed air is ejected from. When the gap between the nozzle and the inner wall of the reference hole changes, the flow rate blown out from the nozzle changes, which changes the floating height of the float, and the inner diameter of the reference hole is measured by moving the position of the float.

The air micrometer includes a two-point type in which air is ejected in two directions (diagonal direction) on both sides and a three-point type in which air is ejected laterally (diameterally) from three points at 120 ° intervals. Considering the ease of measurement and the burden, the two-point method is easier, but in general, when measuring the inner diameter of a hole with an air micrometer, there is no reference point (0 point) in the inner diameter measurement, so skill in measurement technology It was considered preferable to use a three-point air micrometer when it was necessary to find the center of the hole or the center of the hole (centrifugal) and measurement accuracy was required. On the other hand, in the case of measurement with a three-point air micrometer, zero adjustment must be performed with a ring gauge, and measurement is difficult unless the reference hole is a perfect circle, whereas in the case of a two-point air micrometer, it is difficult to measure. Zero adjustment can be performed with a metal fitting, and measurement can be performed even if the circle of the reference hole is distorted. That is, both the two-point type and the three-point type air micrometer have contradictory advantages and disadvantages in the inner diameter measurement, which is one of the factors hindering the spread of the MIRS method and the like.

Japanese Unexamined Patent Publication No. 2007-167937 Japanese Unexamined Patent Publication No. 2015-184118

Therefore, an object of the present invention is to provide an optimum hole diameter measuring method capable of measuring the hole diameter of a reference hole with high accuracy and easily by using an air micrometer in the MIRS method or the like, and an optimum hole diameter measuring device using this method. do.

The present invention
A reference hole in the thickness direction and a trepanning hole hollowed out substantially concentrically to the outside of the reference hole are formed at the measurement point of the member to be measured, and the change in the hole diameter of the reference hole before and after the formation of the trepanning hole is measured. Provided is an optimum hole diameter measuring method in residual stress measurement for calculating residual stress values on the surface and inside of a member to be measured. The hole diameter of the reference hole is measured by having an air probe that is inserted into the reference hole and ejects air flow on both sides (diagonal direction) in the radial direction, and measures the distance from the change in air pressure. Use a micrometer.

Further, the optimum hole diameter measuring method of the present invention is
The reference hole and the trepanning hole are formed by a cutting tool of a machining device having a tool holder that controls the tip position of the cutting tool and grips the cutting tool interchangeably , and the machining device stores the center position of the reference hole. And
To measure the hole diameter of the reference hole, the cutting tool held by the tool holder of the processing device is replaced with the two-point air micrometer, and the cutting tool is located at the center position of the reference hole stored in the processing device. It is preferably performed by inserting an air probe of a two-point air micrometer.

Further, in the present invention, a reference hole in the thickness direction and a reference hole substantially concentric with the reference hole are located at the measurement point of the member to be measured by a processing device having a tool holder that controls the tip position of the cutting tool and grips the cutting tool interchangeably . Optimal for residual stress measurement in which a trepanning hole hollowed out in an annular shape is formed, the change in the hole diameter of the reference hole before and after the formation of the trepanning hole is measured, and the residual stress value on the surface and inside of the member to be measured is calculated. A hole diameter measuring device is provided.
This optimum hole diameter measuring device has an air probe that is inserted into the reference hole to eject an air flow on both sides in the radial direction, and an air probe of a two-point air micrometer that measures a distance from a change in the air pressure of the air flow. Is attached to the tool holder so that it can be replaced with a cutting tool.
The processing apparatus has a configuration in which the center position of the reference hole is stored and the air probe is inserted into the center position.

As described above, an air micrometer or a mechanical / electric micrometer can be considered as a method for measuring the hole diameter, but chips due to drilling adhere to the surface or the inner wall when creating a reference hole. In the case of contact-type mechanical and electric-type micrometer, the measurement accuracy may change depending on the presence or absence of chips. On the other hand, the air micrometer has the effect of blowing off chips by the air flow and is suitable for measuring the hole diameter of the reference hole in the MIRS method or the like. In addition, it is difficult to use a mechanical micrometer when measuring a deep hole and a small diameter such as a reference hole in the MIRS method, because the micrometer itself may be distorted or may be in contact with the inner wall of the hole, making measurement impossible. .. Therefore, it was found that it is preferable to use an air micrometer for measuring the hole diameter of the reference hole such as the MIRS method.

Further, as described above, when measuring the inner diameter of a hole, it has been generally considered that it is preferable to use a three-point air micrometer rather than a two-point air micrometer. However, in the case of the MIRS method, etc., in order to form a reference hole and a trepanning hole by replacing the cutting tool with a cutting device such as a machining center, a cutting tool is replaced with the cutting device to make it a tool holder for the spindle of the machining device. When an air micrometer is attached, the processing device itself sets the center position (reference point) of the reference hole without automatically centering the reference point, so it is a two-point air micrometer that originally requires measurement skill. Even if there is, it can be measured with high accuracy.

Further, in the case of a three-point air micrometer, a measurement error is likely to be included unless the reference hole is a perfect circle. Therefore, it is not preferable to use it for measuring the hole diameter of the reference hole which is deformed into a substantially elliptical shape after the trepanning process. In this respect, in the case of a two-point air micrometer, the zero point can be adjusted by the spindle of the processing device, and it is possible to measure even if the reference hole is distorted during trepanning processing. According to the present invention, since the two-point air micrometer is attached to the spindle of the processing device for drilling the reference hole, the reference position is known on the processing device side, which is a disadvantage of the two-point air micrometer. Can be resolved and only the advantages can be utilized. Therefore, it was found to be the best for measuring the hole diameter by the MIRS method or the like. The present invention is greatly advantageous in that it provides an optimum configuration for hole diameter measurement by the MIRS method or the DHD method.

According to the optimum measuring method of residual stress and the optimum measuring device of residual stress of the present invention, a reference hole can be easily and accurately measured by using an air micrometer in the MIRS method or the like as a residual stress measurement evaluation of various measurement objects. By providing the optimum hole diameter measuring method capable of measuring the hole diameter of the above and the configuration of the optimum hole diameter measuring device using the same, the MIRS method and the like will be standardized in the future, and important measurement methods and measurements will be used by general users. It becomes a device.

(A) to (e) are explanatory views showing each step of residual stress measurement using the optimum pore diameter measuring method of this invention. The perspective view of the cutting device as an example of the processing device in which the air micrometer used in the present invention is attached to the tool holder is shown. A schematic plan view showing the change in the reference hole before and after the trepanning process and the hole diameter to be measured is shown. It is a figure which showed the hole diameter measurement of a reference hole by a three-point type air micrometer. It is a figure which showed the hole diameter measurement of a reference hole by a two-point air micrometer. It is a figure which shows the state of performing the hole diameter measurement of a reference hole by a two-point type air micrometer with a processing apparatus. It is explanatory drawing which showed each process of the residual stress evaluation method by the conventional deep hole drilling method.

(Residual stress measurement method)
first. As a premise for explaining the embodiment of the present invention, the residual stress measurement in which the present optimum hole diameter measuring method is used will be described.
1A to 1E are explanatory views showing each step of residual stress measurement in which the optimum pore size measuring method of the present invention is used. In this residual stress evaluation method, the residual stress value inside the plate thickness is calculated by the five procedures as shown in FIGS. 1 (a) to 1 (e). Here, reference numeral 1 in the drawing is a member to be measured such as a welded structure, and reference numeral 2 is a drill capable of forming a reference hole 10 in the member 1 to be measured. Further, reference numeral 3 is an air probe (hole diameter measuring unit and hole diameter re-measuring unit) capable of measuring the inner diameter of the reference hole 10 formed in the measurement target member 1, and reference numeral 4 is around the reference hole 10 by electric discharge. It is an electric discharge machine capable of forming a trepanning hole 11 by performing a hollowing process (trepanning process). Reference numeral 5 is a touch probe capable of measuring each of the axial extension amount ΔZ and the tilt amount Δθ of the cylindrical portion 12. In this residual stress measurement, at least using the air probe 3, the surface of the member 1 to be measured and the surface of the member 1 to be measured and the surface of the member 1 to be measured by the stress value calculation unit (not shown) based on the shape change of the reference hole 10 before and after the hollowing process (trepanning process). Calculate the internal residual stress value. In calculating the residual stress value, the stress value calculation unit determines the hole diameter of the reference hole 10, the change in length of the reference hole 10 in the longitudinal direction (elongation amount ΔZ), and the inclination of the axis of the reference hole 10 (tilt amount Δθ). Consider.

In FIG. 1, the center position of the reference hole 10 is the origin O, the right direction of the paper surface is the X axis, the back direction perpendicular to the paper surface is the Y axis, and the upper vertical direction is the Z axis. First, in FIG. 1A, a forehead (not shown) is attached to a drilling portion of the member 1 to be measured, and a reference hole 10 is formed by drilling using a drill 2. The reference hole 10 may be a through hole or a semi-through hole. Next, in FIG. 1B, the hole diameter of the reference hole 10 is measured at one or more locations in the longitudinal direction (Z direction) and at three or more locations in the circumferential direction using the air probe 3. In this hole diameter measurement, a two-point air micrometer is used in the optimum hole diameter measuring method of the present invention (described later). Next, in FIG. 1 (c), a hollowing process (trepanning process) is performed on the periphery of the reference hole 10, the restraint of the peripheral portion of the reference hole 10 is released, and the cylindrical cylindrical portion 12 is coaxially formed. do. Then, in FIG. 1D, the hole diameter of the reference hole 10 after the peripheral removal processing is measured again at one or more locations in the longitudinal direction (Z direction) and at three or more locations in the circumferential direction using the air probe 3. Then, in FIG. 1 (e), the amount of elongation (ΔZ) in the axial direction (Z direction) of the cylindrical portion 12 and the amount of tilt (Δθ) in the XY direction are measured using the touch probe 5. By measuring the amount of elongation (ΔZ) and the amount of tilt (Δθ), the residual stress is measured by the conventional method (deep hole drilling method, sequential deep hole drilling method), and the residual stress consists of three (σx, σy, σxy). While only the components are considered, in the residual stress measuring method of the present invention, the residual stress measurement considering the residual stress component consisting of 6 components (σx, σy, σz, σxy, σyz, σzx) is performed. This makes it possible to measure the three-dimensional residual stress component, which was omitted in the previous assumptions, with high accuracy.

<< Overview of air micrometer (2-point type and 3-point type) and reason for adopting 2-point type air micrometer in the present invention >>
The air micrometer used for the hole diameter of the reference hole 10 will be described in detail.
As mentioned above, the air micrometer is a comparative measuring instrument that measures the dimensions of an object by the flow rate of air, and there are measurement methods such as flow rate type and back pressure type (differential pressure method). After creating clean compressed air, it is blown out from the nozzle while keeping it at a constant pressure by the regulator. When the clearance between the nozzle and the object to be measured changes, the flow rate blown out from the nozzle changes, and the floating height of the float changes. The dimensions of the object to be measured can be measured by moving the position of the float. This air micrometer includes a two-point air micrometer and a three-point air micrometer. The two-point air micrometer adopted in the optimum measurement method of the hole diameter of the present invention has two nozzles for ejecting air on both sides in the hole diameter direction (diagonal: 180 ° intervals), and the nozzles are directed toward the inner wall of the reference hole 10. The pore diameter is measured by the amount of movement of the float in the axial direction due to the change in the flow rate of the air ejected. Hereinafter, the reason why the two-point air micrometer is adopted in the present invention will be described.

First, as a premise, the hole diameter of the reference hole 10 before and after the trepanning process for which measurement is actually desired will be described. FIG. 3 shows a schematic plan view showing the change of the reference hole 10 before and after the trepanning process and the hole diameter to be measured, (a) is shown before the trepanning process, and (b) is shown after the trepanning process. In the measurement before the trepanning process, the diameters D1, D2, D3, and D4 are measured at intervals of 45 ° around the center O of the reference hole 10 as shown in (a). After that, an annular trepanning hole 11 (see FIG. 1 (d)) is formed around the outer periphery of the reference hole 10 to release residual stress, and then, as shown in (b), the diameters D1, D2, D3 before trepanning are processed. The diameters D1', D2', D3', and D4'of the reference hole 10'in phase with D4 are measured. As can be seen from FIG. 3, it was found that when the trepanning process is performed, the reference hole 10 having a substantially perfect circle is usually transformed into the reference hole 10'which has a substantially ellipse shape.

Next, the advantages and disadvantages of the hole diameter measurement by the three-point air micrometer and the hole diameter measurement by the two-point air micrometer will be specifically described.
FIG. 4 shows the diameter measurement (hole diameter measurement) of the reference hole 10 by a three-point air micrometer. In the case of measurement with a three-point air micrometer, nozzle portions 3a, 3b, and 3c are radially provided at intervals of 60 ° around the central axis of the air probe 3 as shown in FIG. Inject air toward the inner wall. When the reference hole 10 is a perfect circle, when air is injected from the nozzle portions 3a, 3b, and 3c, the central axis of the air probe 3 is automatically positioned at the center O of the reference hole 10 at a position where the air pressures in the three directions are balanced. Will be done. Then, the diameter value in the diagonal direction from the position of the reference nozzle portion 3a is adopted as the diameter value of the diameter D1 (see FIG. 4B). Since such an automatic centripetal action works in a three-point air micrometer, there is little error even for a measurer who does not have measurement skills. Therefore, a three-point air micrometer is generally used for measuring the hole diameter, and the same applies to the MIRS method and the like.

On the other hand, in the hole diameter measurement of the reference hole 10 by the MIRS method or the like, it is necessary to measure the diameter values D1 to D4 of each phase as shown in FIG. This is because, as described above in FIG. 3B, the reference hole 10'after the trepanning process is substantially elliptical, and the diameter values D1 to D4 of the respective phases are different. Therefore, in the case of a three-point air micrometer, it was found that if the air probe 3 is an ellipse that is eccentric even if it is automatically centered, it is not possible to grasp the appropriate diameter values D1 to D4 (FIG. 4 (c)). reference).

FIG. 5 shows the diameter measurement (hole diameter measurement) of the reference hole 10 by a two-point air micrometer. In the case of measurement with a two-point air micrometer, nozzle portions 3d and 3e are provided diagonally (at intervals of 90 ° in the hole diameter direction) around the central axis of the air probe 3 as shown in FIG. Air is injected in the direction of the inner wall of the hole 10 (diagonal direction), and the central axis of the air probe 3 is positioned at a position where the air pressures in the two directions are balanced. Then, the diameter value in the diagonal direction from the position of the reference nozzle portion 3d is adopted as the diameter value of the diameter D1 (see FIG. 5B). In the case of a two-point air micrometer, unlike a three-point air micrometer, there is no automatic centripetal action and the distance to the inner wall of the reference hole 10'is long even if it is deformed into a substantially elliptical reference hole 10'after trepanning. In that sense, it is possible to measure appropriate diameter values D1 to D4 because they are balanced.

On the other hand, in the case of measurement with a two-point air micrometer, as shown in FIG. 5D, if the measuring skill of the measurer is low, the axis of the air probe 3 is inserted in a state of being deviated from the center O of the reference hole 10. There is a problem that the distance from the nozzle portions 3d and 3e to the inner wall at the displaced position is measured as the diameter value D1, and even the measurement of the diameter value before the trepanning process contains an error. rice field.

On the other hand, in the optimum hole diameter measuring method of the present invention, it is recommended to measure with a two-point air micrometer so that the reference hole 10 which is deformed after the trepanning process and has a substantially elliptical shape can be appropriately measured by the MIRS method or the like. The problem that the air probe 3 is misaligned and inserted into the reference hole 10 is solved by mounting the air probe 3 on the tool holder of the spindle of the processing apparatus. First, the reference hole 10 is drilled with a cutting tool attached to the tool holder of the processing apparatus. The machining apparatus automatically controls the movement of the cutting tool by calculating it from the preset position coordinates. Therefore, the coordinates of the center position of the tool or the like held by the tool holder are stored. Therefore, as shown in FIG. 6A, the center position O stores the XY coordinate positions (x1, y1) when the reference hole 10 is drilled, and the drill is removed from the tool holder to obtain an air probe. When 3 is attached, when it is inserted into the reference hole 10 with the XY coordinate position of its central axis maintained at (x1, y1), the hole diameter is not measured at a displaced position as shown in FIG. 6 (d). .. Further, when the hole diameter of the reference hole 10'is measured again after the trepanning process, the hole diameter can be measured with the XY coordinate position of the central axis of the air probe 3 also in the state of (x1, y1).

<< Overview of drilling and hole diameter measurement examples using a cutting device equipped with a two-point air micrometer >>
FIG. 2 shows a perspective view of a cutting device 100 as an example of a processing device in which the air micrometer used in the present invention is attached to the tool holder. The cutting device 100 generally includes a tool holder grip portion 105, a member installation surface 102a (not shown) on which a member to be measured 1 is placed, a work stage 102, a head abutment 108, and a head 107. , And an operation panel 106.

First, the tool holder grip portion 105 is rotationally contacted (contact direction = arrow Z direction, rotational direction) with the measurement position (center position of the reference hole 10) of the residual stress of the measurement target member 1 (see FIG. 1) to be machined. = Attach the tool holder 104 holding the drill 2 (see FIG. 1) to be made (in the direction around the axis of the arrow Z). As a result, the tool holder grip portion 105 at the lower end of the spindle 101, the tool holder 104, and the drill 2 rotate integrally. Further, the member to be measured (member to be measured) 2 is placed on the member installation surface 102a on the upper surface of the work stage 102 that moves in the X direction on the base 103, and is fixed as a fixing clamp (not shown) or fixed. It is fixed using a port (not shown) or the like.

The operator operates the operation panel 106 to move the work stage 102 in the X direction, and stops and positions the measurement target member 2 at a position where the drill 2 is located directly above the center position of the desired reference hole 10. Next, the operation panel 106 is operated in a state of being stopped and positioned on the member to be machined, and in addition, the drill 2 is lowered and rotated while being in contact with the position of the reference hole 10 of the member 1 to be measured to rotate the reference hole. When the 10 is drilled, the drill 2 rises and temporarily stops. When drilling a plurality of reference holes 10 in succession, move the work stage 102 without stopping, stop and position the drill 2 directly above the center position of the next reference hole, and then stop and position the drill 2 again. The drill 2 is rotated while being lowered / contacted, and is raised to stop when there is no reference hole to be drilled.

When the reference hole 10 is formed, the drill 2 is removed from the tool holder 104 of the stopped processing device, replaced with the air probe 3 of the air micrometer, and the air probe 3 is lowered as shown in FIG. 1 (b) for reference. It is inserted into the hole 10 and the air ejection nozzle of the air probe 3 is positioned at a desired depth position for measuring the hole diameter. Then, air from a compressor (not shown) is ejected on both sides in the direction of the inner wall to measure the hole diameter. When a plurality of reference holes are continuously drilled, the air probe 3 is inserted by moving to the center position coordinates of the reference holes 10 stored in advance as operating conditions. Further, after inserting the air probe 3, an air flow is ejected from the nozzle to measure the hole diameter, and the air probe 3 is raised to be removed from the reference hole 10.

Next, the air probe 3 is removed from the tool holder 104, replaced with the electric discharge machine 4, and the electric discharge machine 4 is lowered and discharged as shown in FIG. 1 (c) to perform trepanning processing and concentric with the reference hole 10. Form an annular circle. The trepanning process is performed at a preset distance in the depth direction. When the trepanning process is completed, the electric discharge machine 4 is raised. Then, the electric discharge machine 4 is removed from the tool holder 104 again, replaced with the air probe 3, the air probe 3 is lowered as shown in FIG. 1D, inserted into the reference hole 10, and the hole diameter is before the trepanning process. The air ejection nozzle of the air probe 3 is positioned at the measured depth position, and air is ejected from the air probe 3 again as described above to measure the hole diameter.

As described above, the hole diameter of the reference hole 10 before and after the trepanning process is measured. It should be noted that the subsequent description of FIG. 1 (e) will be omitted here. Further, in the series of operations of this metal processing apparatus, the operator previously performs the moving coordinates and moving speed (or rotation speed) of the drill 2, the air probe 3, and the electric discharge machine 4 on the operation panel 106, and the load and air applied to them. Each parameter such as quantity and power is input and set, and the machining device is controlled based on the set parameter.

Although the embodiments of the present invention have been described above with reference to the drawings, it goes without saying that the specific configuration is not limited to these embodiments. The scope of the present invention is shown by the scope of claims rather than the description of the embodiment described above, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

1 Member to be measured 2 Drill 3 Air probe 3a, 3B, 3C, 3D, 3E Nozzle part 4 Electric discharge machine 5 Touch probe 10, 10'Reference hole 11 Hollow hole (trepanning hole)
12 Cylindrical part 100 Processing equipment (cutting equipment)
101 Main shaft 102 Work stage 102a Work member installation surface 103 Base 104 Tool holder 105 Tool holder grip 106 Operation panel 107 Head 108 Head abutment O Center D1, D2, D3, D4 Diameter D1', D2', D3', D4'diameter

Claims (3)

A reference hole in the thickness direction and a trepanning hole hollowed out substantially concentrically to the outside of the reference hole are formed at the measurement point of the member to be measured, and the change in the hole diameter of the reference hole before and after the formation of the trepanning hole is measured. In the optimum pore size measurement method in residual stress measurement for calculating residual stress values on the surface and inside of the member to be measured.
The measurement of the hole diameter of the reference hole is
An optimum hole diameter measuring method using an air probe that is inserted into the reference hole and ejects an air flow on both sides in the radial direction, and a two-point air micrometer that measures a distance from a change in the air pressure of the air flow. The reference hole and the trepanning hole are formed by a cutting tool of a processing device having a tool holder that controls the tip position of the cutting tool and grips the cutting tool interchangeably .
The processing apparatus stores the center position of the reference hole, and the processing device stores the center position of the reference hole.
The measurement of the hole diameter of the reference hole is
The cutting tool held by the tool holder of the processing device is replaced with the two-point air micrometer, and the air probe of the two-point air micrometer is located at the center position of the reference hole stored in the processing device. The optimum hole diameter measuring method according to claim 1, which is performed by inserting the. A processing device having a tool holder that controls the tip position of the cutting tool and grips the cutting tool in a replaceable manner. In the optimum hole diameter measuring device used for residual stress measurement, which forms a hole, measures the change in the hole diameter of the reference hole before and after the formation of the trepanning hole, and calculates the residual stress value on the surface and inside of the member to be measured.
The air probe of a two-point air micrometer that has an air probe that is inserted into the reference hole and ejects air flow on both sides in the radial direction and measures the distance from the change in the air pressure of the air flow can be replaced with a cutting tool. Attached to the tool holder
The processing device is an optimum hole diameter measuring device that stores the center position of the reference hole and inserts the air probe into the center position.

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