Lever type aperture measuring device and residual stress measuring method

Abstract

This invention belongs to the field of precision measurement technology, specifically a lever-type aperture measuring device and a residual stress measuring method. The device includes a lever unit, a resistance unit, and a signal processing unit. The lever unit includes a rotating shaft and a lever rotatably connected to the shaft. The lever is divided into a short arm and a long arm by the shaft. The short arm extends into the aperture to be measured, and its rotation contacts the aperture wall to measure the aperture diameter. The end of the long arm is slidably connected to the resistance unit, used to adjust the effective length of the resistance as the lever rotates. The signal processing unit processes the electrical signal from the resistance unit to obtain the movement distance of the short arm, and thus the aperture diameter of the aperture to be measured. This invention is based on the lever amplification and resistance transformation principles, converting minute dimensional changes into electrical signals through a mechanical mechanism, thereby achieving high-precision measurement of deep apertures.

Description

Technical Field

[0001] This invention belongs to the field of precision measurement technology, specifically relating to a lever-type aperture measuring device and a method for measuring residual stress. Background Technology

[0002] The deep-hole method is the most common approach for residual stress measurement. This method involves drilling a series of holes in the material to measure the residual stress within these holes, and then measuring the change in hole diameter caused by the residual stress within the holes to determine the magnitude of the residual stress. A key challenge in the deep-hole method is accurately measuring the minute diameter of the drilled holes while minimizing cost and technical complexity. Existing methods include pneumatic gauges, optical microscopes, and electronic plug gauges, but these technologies have significant limitations: pneumatic gauges are complex and expensive; optical methods require strict environmental cleanliness and lighting conditions and are difficult to apply to deep holes; electronic plug gauges are expensive to manufacture and their probes are prone to wear. Furthermore, existing manual measuring tools suffer from low positioning accuracy, reliance on manual operation leading to large errors, and an inability to adapt to multi-angle and multi-depth measurements.

[0003] Therefore, there is an urgent need for a micro-aperture measurement solution that is simple in structure, easy to operate, low in cost, and can maintain high measurement accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a lever-type aperture measuring device and a residual stress measuring method. Based on the lever amplification and resistance transformation principle, the device converts minute dimensional changes into electrical signals through a mechanical mechanism, thereby achieving high-precision measurement of deep apertures.

[0005] To achieve the above objectives, the present invention provides a lever-type aperture measuring device, comprising: a lever unit, a displacement detection unit, and a signal processing unit; the lever unit includes a rotating shaft and a lever rotatably connected to the rotating shaft, the lever being divided into a short lever arm and a long lever arm by the rotating shaft; The lever arm is used to extend into the small hole to be measured. The measuring probe fixed at the end of the lever is rotated until it touches the hole wall to measure the hole diameter. The end of the long arm of the lever is slidably connected to the displacement detection unit, and is used to push the displacement detection unit to move as the lever rotates; The signal processing unit is used to process the signal from the displacement detection unit to obtain the moving distance of the lever arm and thus the diameter of the hole to be measured.

[0006] Furthermore, the length ratio of the short lever arm to the long lever arm is less than or equal to 1:10; the end diameter of the short lever arm is less than or equal to 0.1 mm.

[0007] Furthermore, the displacement detection unit is a resistive displacement detection unit, a scale, or a displacement sensor; the displacement detection unit is provided with a guide rail parallel to the horizontal displacement direction of the lever arm and a slide groove perpendicular to the direction of the guide rail, and the end of the lever arm is connected to the slide groove.

[0008] Furthermore, the resistive displacement detection unit includes a sliding rheostat brush, a sliding rheostat resistor body, and a guide rail; the end of the lever arm is slidably connected to the sliding rheostat brush, the sliding rheostat brush is sleeved on the guide rail and is in contact with the sliding rheostat resistor body, and is used to change the effective length of the sliding rheostat resistor body by sliding.

[0009] Furthermore, the sliding rheostat brush is provided with a groove perpendicular to the direction of the guide rail, and the end of the lever arm is slidably connected to the groove. The groove is used to eliminate the vertical displacement in the arc displacement of the lever arm, remove the error it generates, and convert the horizontal displacement of the lever arm into the effective length of the resistor.

[0010] Furthermore, the signal processing unit is connected to one end of the sliding rheostat resistor and one end of the sliding rheostat brush via a signal output line to form a closed loop, thereby obtaining an electrical signal indicating the effective length of the sliding rheostat resistor.

[0011] Furthermore, the lever-type aperture measuring device also includes a displacement platform, and the lever unit also includes a central shaft fixedly connected to the displacement platform. The central shaft is also fixedly connected to the rotating shaft for controlling the movement of the lever through the displacement platform.

[0012] Furthermore, the diameter ratio of the central shaft to the lever is greater than or equal to 5:1; the central shaft is also connected to a fixed support fixed on the central shaft.

[0013] Furthermore, the fixed support will be fixed to the hole wall to prevent the central shaft from deforming and displacing.

[0014] Furthermore, the displacement platform also includes a mechanism for controlling the rotation of the lever and a component for measuring the rotation angle. The displacement information and angle information of the displacement platform are both transmitted and connected to the signal processing unit.

[0015] The present invention also provides an aperture measurement method, employing the lever-type aperture measuring device described in any of the above claims, comprising the following steps: S1. Insert the lever of the lever unit into the target depth of the hole to be measured; S2. Then rotate the lever around the pivot. After the measuring probe of the short arm of the lever touches the hole wall, read the displacement number, and then rotate the lever back to the initial position. S3. Rotate the lever or the hole to be measured within the target depth section by a preset angle, and then repeat step S2 to obtain an electrical signal; S4. Repeat step S3 until one circumference of the hole to be measured is completed. The signal processing unit processes each displacement signal to obtain the actual length inside the hole for each test. Combined with the position of the rotating shaft and the rotation angle each time, the diameter of the hole at the target depth of the hole to be measured is obtained.

[0016] Furthermore, when the centers of the circles at each depth of the hole to be measured are coaxial and the hole to be measured is a regular circle, in step S1, the lever is inserted from the center of the opening end of the hole to be measured, and in step S3, the lever or the hole to be measured is rotated 180 degrees, and the diameter of the hole to be measured is obtained only twice. When the hole to be tested is irregular, or the centers of the circles at different depths are not on the same axis, the preset angle mentioned in step S3 is less than or equal to 30 degrees.

[0017] The present invention also provides a method for measuring residual stress, comprising: drilling a hole in a workpiece, using the lever-type hole diameter measuring device to penetrate along the depth direction and measuring the internal hole diameter corresponding to each depth of the hole, then drilling a ring hole outside the hole to release the residual stress of the workpiece, then using the lever-type hole diameter measuring device to penetrate along the depth direction and measuring the internal hole diameter corresponding to each depth of the hole, and measuring the residual stress using the deep hole method based on the hole diameter change.

[0018] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: 1. The lever-type aperture measuring device provided by the present invention amplifies the minute displacement inside the hole through a mechanical lever, thereby improving the measurement accuracy. The lever amplification mechanism reduces the requirements for sensor resolution. At the same time, the slender structure of the lever facilitates deep penetration into the hole, which helps to realize aperture measurement inside deep holes.

[0019] 2. This invention utilizes a sliding rheostat to convert displacement into resistance change, and finally achieves indirect aperture measurement through electrical signal processing. It has a compact mechanical structure, low cost, high precision, and is easy to carry and operate, making it suitable for industrial sites.

[0020] 3. This invention introduces a three-axis platform and control module to achieve probe positioning and data processing, resulting in high overall measurement accuracy and avoiding eccentricity errors. The electrical signals facilitate connection to digital instruments or computers, enabling automated data processing and recording. 4. The testing method provided by this invention can be used for blind hole or through hole measurement, has low environmental requirements, and can be adapted to deformed small holes (such as elliptical holes) after stress release. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the lever-type aperture measuring device of the present invention.

[0022] Figure 2 This is a perspective view of the lever-type aperture measuring device of the present invention.

[0023] Figure 3 This is a schematic diagram of a cross-section with the central axis as the measurement point.

[0024] Figure 4 This is a schematic diagram of the cross-section of the small hole obtained after rotation measurement.

[0025] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-Measuring probe; 2-Short lever arm; 3-Rotating shaft; 4-Lever long arm; 5-Sliding rheostat brush; 6-Sliding rheostat resistor element; 7-Signal output line; 8-Guide rail; 9-Measured small hole; 10-Central shaft; 11-Slide groove; 12-Fixed support. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Please see Figure 1-2 The present invention provides a lever-type aperture measuring device, comprising: a lever unit, a displacement detection unit and a signal processing unit; the lever unit includes a rotating shaft 3 and a lever rotatably connected to the rotating shaft 3, the lever being divided by the rotating shaft 3 into a short lever arm 2 and a long lever arm 4; The lever arm 2 is used to extend into the small hole to be measured. The lever is rotated until the measuring probe 1 installed at the end of the lever arm 2 touches the hole wall to measure the hole diameter. The end of the lever arm 4 is slidably connected to the displacement detection unit, and is used to adjust the effective length of the resistor as the lever rotates; The signal processing unit is used to process the electrical signal of the displacement detection unit to obtain the moving distance of the lever arm 2, and then to obtain the aperture of the hole to be measured.

[0028] This setup amplifies the probe's minute displacement within the aperture using a mechanical lever, converts the displacement into a change in resistance using a sliding rheostat, and finally achieves indirect aperture measurement through electrical signal processing. It boasts advantages such as compact structure, low cost, high precision, portability, and ease of operation.

[0029] The lever arm 2 (as shown) Figure 1 L2) and lever arm 4 ( Figure 1 The length ratio of L1 to the length of the lever arm 2 is less than or equal to 1:10 to maximize the displacement within the hole; the end diameter of the lever arm 2 is less than or equal to 0.1 mm. Specifically, a measuring probe 1 is connected to the end of the lever arm 2 for direct contact with the inner wall of the hole being measured. The diameter of the measuring probe 1 is less than or equal to 0.1 mm to reduce measurement error; error compensation can also be achieved by adjusting the diameter of the measuring probe.

[0030] The displacement detection unit is a resistive displacement detection unit, a scale, or a displacement sensor. The displacement detection unit has a guide rail 8 parallel to the horizontal displacement direction of the long lever arm 4, and a groove 11 perpendicular to the direction of the guide rail 8. The end of the long lever arm 4 is connected to the groove 11. This configuration allows the distance the displacement detection unit moves to be the horizontal movement distance of the long lever arm 4, which can be converted into the horizontal movement distance of the short arm, i.e., the distance from the rotating shaft 3 to the hole wall.

[0031] Specifically, the resistive displacement detection unit includes a sliding rheostat brush 5, a sliding rheostat resistor 6, and a guide rail 8; the end of the lever arm 4 is slidably connected to the sliding rheostat brush 5, the sliding rheostat brush 5 is sleeved on the guide rail 8 and is in contact with the sliding rheostat resistor 6, and is used to change the effective length of the sliding rheostat resistor 6 by sliding.

[0032] Specifically, the sliding rheostat brush 5 is provided with a groove 11 perpendicular to the direction of the guide rail 8. The end of the lever arm 4 is slidably connected to the groove 11, which is used to convert the horizontal displacement of the lever arm 4 into an equivalent amount of the effective length of the resistor. With this configuration, the change in the resistance length of the present invention is the lateral displacement of the end of the lever arm 4. By the lever length ratio, the lateral displacement of the end of the lever arm 2 can be obtained, which is also the vertical distance between the rotating shaft 3 and the hole wall. If the rotating shaft 3 is located on the central axis of the hole, the obtained distance is the radius of the hole, thereby eliminating the error caused by the vertical displacement of the arc displacement.

[0033] The sliding rheostat resistor 6 is made of conductive plastic potentiometer or precision wire-wound potentiometer with high linearity and long mechanical life, and is sealed in the housing to prevent dust from affecting it.

[0034] The signal processing unit is connected to one end of the sliding rheostat resistor 6 and one end of the sliding rheostat brush 5 via the signal output line 7, forming a closed loop to obtain an electrical signal indicating the effective length of the sliding rheostat resistor 6. When the lever rotates, the effective length of the sliding rheostat resistor 6 increases, and the resistance increases. The change in length can be obtained through signal processing, and then the displacement of the short arm can be obtained through the ratio of the long and short arms of the lever. This achieves signal amplification and automatic processing, improving the accuracy of aperture detection.

[0035] The lever-type aperture measuring device further includes a displacement platform. The lever unit also includes a central shaft 10 fixedly connected to the displacement platform. The central shaft is also fixedly connected to the rotating shaft, and is used to control the movement of the lever through the displacement platform. The diameter ratio of the central shaft to the lever is greater than or equal to 5:1. The central shaft is also connected to a fixed support 12 fixed to the central shaft. The fixed support is fixed to the hole wall to prevent deformation and displacement of the central shaft. The central shaft 10 serves to fix and support the rotating shaft 3, and also serves to position the lever to determine the test center.

[0036] Specifically, the displacement platform includes an X-axis slide, a Y-axis slide, and a Z-axis slide, used to achieve precise spatial adjustment of the measuring probe. The X-axis slide is horizontally positioned, the Y-axis slide is slidably connected to the moving end of the X-axis slide, and the Z-axis slides vertically above the X-axis slide, forming a three-dimensional Cartesian coordinate system moving device. Each of the X-axis, Y-axis, and Z-axis slides is equipped with a stepper motor and a linear encoder. The stepper motor drives the slide movement, and the linear encoder provides real-time feedback of the slide displacement data to ensure positioning accuracy.

[0037] The probe is fixed to the Z-axis slide of the three-axis platform via a connector and can move with the platform.

[0038] The displacement platform also includes a mechanism for controlling the rotation of the lever and a component for measuring the rotation angle. The displacement and angle information of the displacement platform are transmitted and connected to the signal processing unit. Using the angle and displacement information, the aperture depth and test center of the lever can be determined, and thus the cross-section of the hole at the test depth can be drawn, naturally yielding the aperture diameter.

[0039] Specifically, the signal processing unit includes a PLC controller, a constant current source, an analog-to-digital converter (ADC), and a microprocessor (MCU). The PLC controller is connected to the stepper motors and linear scales of the three-axis platform to control the movement of the slide table and precise positioning; the control console below the measurement platform is used to control the position coordinates of the small hole, set measurement parameters, and display measurement data; the constant current source, ADC, and MCU are used to provide stable current, acquire voltage signals, and calculate the hole diameter.

[0040] like Figure 1The mechanical amplification principle of this invention is as follows: The lever system is centered on a rotating shaft, with the short arm (length L2) connecting to the measuring probe and the long arm (length L1) connecting to the transmission mechanism (sliding rheostat brush 5). When the probe produces a small radial displacement within the small hole... At that time, the end of the long arm produces an amplified displacement. The relation is: ) By designing a high lever ratio (such as 10:1 or higher), micron-level aperture changes are converted into millimeter-level displacements, facilitating measurement.

[0041] Electrical conversion principle: amplifying displacement Drive the sliding rheostat brush 5 to move. Let the total length of the rheostat be X and the total resistance be... Then the change in resistance R is: The device uses a constant current source. Power supply, output voltage U is: U = = After substituting the lever relationship, U and the change in aperture... It exhibits a linear proportion. Through calibration, the signal processing equipment can directly convert the voltage value into the aperture size.

[0042] Positioning principle: The three-axis platform uses a linear encoder to provide displacement data, and the PLC controller controls the stepper motor to drive the slide, ensuring the measuring probe is precisely aligned with the center of the small hole, avoiding eccentricity errors. Combined with coordinate control from the console, self-positioning is achieved.

[0043] Please see Figure 3 and 4 The present invention also provides an aperture measurement method, employing the lever-type aperture measuring device described in any of the above claims, comprising the following steps: S1. Insert the lever of the lever unit into the target depth of the hole to be measured; S2. Then rotate the lever around the pivot. After the end of the short arm 2 of the lever touches the hole wall, read the displacement signal to obtain... Figure 4 Then, turn the lever to its initial position using L3; S3. Rotate the lever or the hole to be measured within the target depth section by a preset angle, and then repeat step S2 to obtain an electrical signal; S4. Repeat step S3 until one circumference of the hole to be measured is completed. The signal processing unit processes each displacement signal to obtain the actual length inside the hole for each test. Combined with the position of the rotating shaft and the rotation angle each time, the diameter of the hole at the target depth of the hole to be measured is obtained.

[0044] Specifically, before step S1, device calibration is performed. The control module is powered on, and the three-axis platform is moved to the calibration station via the control console. The measuring probe is closed (at the zero position), and the zeroing button is pressed to complete the zero-point calibration. Then, the control console is used to move the X-axis and Y-axis slides, aligning the measuring probe directly above the small hole. The Z-axis slide is then lowered to insert the probe into the small hole until it contacts the hole wall. After contact with the hole wall, a small radial displacement occurs. Amplified and converted through leverage The sliding rheostat brushes move, causing changes in output resistance. The signal processing module acquires the voltage signal in real time, calculates the aperture size, and displays it on the screen. It records the current aperture data, measurement position, and angle. By changing the Z-axis coordinate or rotating the measured component, the test steps are repeated to achieve multi-depth and multi-angle measurements. The power is turned off after the measurement is complete.

[0045] Furthermore, when the centers of the circles at each depth of the hole to be measured are coaxial and the hole to be measured is a regular circle, in step S1, the lever is inserted from the center of the opening end of the hole to be measured, and in step S3, the lever or the hole to be measured is rotated 180 degrees, and the diameter of the hole to be measured is obtained only twice. When the hole to be measured is irregular, or the centers of the circles at different depths are not aligned, the smaller the preset angle (less than or equal to 30 degrees) mentioned in step S3, the higher the measurement accuracy. In actual testing, the rotation angle is adjusted each time according to requirements. By continuously changing the probe direction, the outline of the hole cross-section can be roughly drawn, and the change in hole diameter at that specific depth can be calculated. Figure 3 and 4 Point P is the projection point of the central axis 10 on the cross section of the hole.

[0046] With the testing method of this invention, when the testing accuracy requirement is not high, the center of the circle can be determined first at the opening end of the hole during the initial test, which is used as the center of the lever test, that is, the center of the circle inside the hole is assumed. Then, the radius of the hole can be roughly obtained by only one measurement. In order to improve the measurement accuracy, the hole can be rotated and multiple tests can be performed to obtain the radius by taking the average value.

[0047] In particular, when the hole depth is large and the internal hole diameter is irregular or the center is off, the testing method of the present invention can solve this problem well. There is no need to align the rotating shaft with the center. By rotating 360 degrees to measure the distance from the hole wall to the measurement point at several points, the final hole cross section can be obtained, and the diameter is also obtained accordingly. The shape distribution of the hole can be seen more intuitively.

[0048] The present invention also provides a method for measuring residual stress, comprising: drilling a hole in a workpiece, using the lever-type hole diameter measuring device to penetrate along the depth direction and measuring the internal hole diameter corresponding to each depth of the hole, then drilling a ring hole outside the hole to release the residual stress of the workpiece, then using the lever-type hole diameter measuring device to penetrate along the depth direction and measuring the internal hole diameter corresponding to each depth of the hole, and measuring the residual stress using the deep hole method based on the hole diameter change.

[0049] In summary, this invention is suitable for high-precision, low-cost internal diameter measurement of small holes (typically referring to diameters less than 5 mm), especially for mechanical indirect measurement of small hole internal diameters. This invention combines triaxial platform positioning technology to achieve accurate measurement of small hole diameters, and is particularly suitable for deep-hole methods in residual stress measurement experiments.

[0050] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lever-type aperture measuring device, characterized in that, include: The lever unit includes a lever unit, a displacement detection unit, and a signal processing unit; the lever unit includes a rotating shaft (3) and a lever rotatably connected to the rotating shaft (3), the lever being divided by the rotating shaft (3) into a short lever arm (2) and a long lever arm (4). The lever arm (2) is used to extend into the hole to be measured, and the measuring probe (1) fixed at the end of the lever is rotated until it touches the hole wall to measure the hole diameter. The end of the lever arm (4) is slidably connected to the displacement detection unit, and is used to push the displacement detection unit to move as the lever rotates; The signal processing unit is used to process the signal of the displacement detection unit to obtain the moving distance of the lever arm (2) and then obtain the aperture of the hole to be measured.

2. The lever-type aperture measuring device according to claim 1, characterized in that, The length ratio of the short lever arm (2) to the long lever arm (4) is less than or equal to 1:10; the end diameter of the short lever arm (2) is less than or equal to 0.1 mm.

3. The lever-type aperture measuring device according to claim 1, characterized in that, The displacement detection unit is a resistive displacement detection unit, a scale or a displacement sensor; the displacement detection unit is provided with a guide rail (8) parallel to the horizontal displacement direction of the lever arm (4) and a slide groove (11) perpendicular to the direction of the guide rail (8), and the end of the lever arm (4) is connected to the slide groove (11).

4. The lever-type aperture measuring device according to claim 3, characterized in that, The resistive displacement detection unit includes a sliding rheostat brush (5), a sliding rheostat resistor (6), and a guide rail (8); the end of the lever arm (4) is slidably connected to the sliding rheostat brush (5), the sliding rheostat brush (5) is sleeved on the guide rail (8) and is in contact with the sliding rheostat resistor (6), and is used to change the effective length of the sliding rheostat resistor (6) by sliding.

5. The lever-type aperture measuring device according to claim 4, characterized in that, The sliding rheostat brush (5) is provided with a groove (11) perpendicular to the direction of the guide rail (8), and the end of the lever arm (4) is slidably connected to the groove (11); wherein the groove (11) is used to eliminate the vertical displacement in the arc displacement of the lever arm (4), remove the error it generates, and convert the horizontal displacement of the lever arm (4) into the effective length of the resistor.

6. The lever-type aperture measuring device according to claim 4, characterized in that, The signal processing unit is connected to one end of the sliding rheostat resistor (6) and one end of the sliding rheostat brush (5) via the signal output line (7) to form a closed loop, so as to obtain the electrical signal of the effective length of the sliding rheostat resistor (6).

7. The lever-type aperture measuring device according to claim 1, characterized in that, The lever-type aperture measuring device also includes a displacement platform, and the lever unit also includes a central shaft (10) fixedly connected to the displacement platform. The central shaft (10) is also fixedly connected to the rotating shaft (3) for controlling the movement of the lever through the displacement platform. The displacement platform also includes a mechanism for controlling the rotation of the lever and a component for measuring the rotation angle. The displacement information and angle information of the displacement platform are both transmitted and connected to the signal processing unit.

8. A method for measuring aperture, characterized in that, The lever-type aperture measuring device according to any one of claims 1-7 includes the following steps: S1. Insert the lever of the lever unit into the target depth of the hole to be measured; S2. Then rotate the lever around the pivot. After the measuring probe (1) of the lever short arm (2) touches the hole wall, read the displacement signal and then rotate the lever to the initial position. S3. Rotate the lever or the hole to be measured within the target depth section by a preset angle, and then repeat step S2 to obtain an electrical signal; S4. Repeat step S3 until one circumference of the hole to be measured is completed. The signal processing unit processes each displacement signal to obtain the actual length inside the hole for each test. Combined with the position of the rotating shaft and the rotation angle each time, the diameter of the hole at the target depth of the hole to be measured is obtained.

9. The aperture measurement method according to claim 8, characterized in that, When the centers of the circles at each depth of the hole to be measured are coaxial and the hole to be measured is a regular circle, in step S1, the lever is inserted from the center of the opening end of the hole to be measured, and in step S3, the lever or the hole to be measured is rotated 180 degrees, and the diameter of the hole to be measured is obtained only twice. When the hole to be tested is irregular, or the centers of the circles at different depths are not on the same axis, the preset angle mentioned in step S3 is less than or equal to 30 degrees.

10. A method for measuring residual stress, characterized in that, The method includes: drilling a hole in a workpiece, using the lever-type hole diameter measuring device as described in any one of claims 1-7 to penetrate along the depth direction and measure the internal hole diameter corresponding to each depth of the hole, then drilling a ring hole outside the hole to release the residual stress of the workpiece, then using the lever-type hole diameter measuring device to penetrate along the depth direction and measure the internal hole diameter corresponding to each depth of the hole, and measuring the residual stress using the deep hole method based on the hole diameter change.

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