A rapid method for measuring the pitch diameter and tooth height of pipe internal threads

Abstract

This invention discloses a rapid measurement method for the dimensional parameters of internal pipe threads, which is based on a coordinate measuring machine (CMM). The method includes the following steps: 100: Establish a measurement coordinate system, wherein the origin O of the measurement coordinate system is the intersection of the axial end face of the pipe and the central axis of the pipe, the Z-axis of the measurement coordinate system coincides with the central axis of the pipe, and the X-axis and Y-axis of the measurement coordinate system point to the radial direction of the pipe; 200: Move the probe of the CMM from the origin of the measurement coordinate system along the Z-axis to the measurement surface. On the measurement surface, the probe makes contact points on the inner wall of the pipe along the circumferential direction of the pipe, obtaining n contact points evenly distributed in the circumferential direction. Record the distance from each contact point to the Z-axis to obtain n measurement values; wherein n≥n0, and n0 is the minimum number of contact points required to ensure that at least one contact point falls on the root and tip of the internal thread respectively; 300: Calculate the tooth height, tip diameter, and root diameter of the internal thread based on the measurement values.

Description

Technical Field

[0001] This invention relates to a measurement method, and more particularly to a rapid measurement method for the pitch diameter and tooth height of a thread. Background Technology

[0002] An oil well tubing string is composed of individual oil pipes connected by specialized threads, and the threaded connection is the weakest point of the tubing string. Downhole, the oil pipe typically withstands combined loads of tension / compression, internal / external pressure, and bending. Under these conditions, whether the sealing and strength of the threaded connection can reach the level of the pipe body directly affects the load-bearing capacity of the oil well string, and thus determines the safety, reliability, and service life of the oil and gas well.

[0003] With the increasing demands of oilfield applications, special threaded joints are gaining attention due to their ability to meet higher requirements for anti-crushing and gas-tight performance. The design and fabrication of the thread structure, along with subsequent dimensional inspection, are crucial for ensuring product quality. Currently, the main thread types for special threaded joints are trapezoidal and their improved forms.

[0004] Traditional thread measurement mainly relies on manual hand-held measuring instruments to measure a single parameter, with the measurement reference fixed to the structure of the measuring instrument itself.

[0005] With the advancement of intelligent manufacturing, digital automatic measurement technology has also begun to flourish. Digital measurement technology is mainly divided into contact measurement and non-contact measurement. Non-contact measurement, due to its limitations in measurement accuracy, environmental sensitivity, and complex processes, requires further development and research in the measurement of internal threads. Contact measurement, on the other hand, has a promising future in internal thread measurement due to its high environmental tolerance, high measurement accuracy, and simple process. Contact measurement often employs coordinate measuring machines (CMMs).

[0006] During measurement, the thread pitch diameter is one of the core parameters of oil pipe threads. By influencing the thread fit and interference fit, it further determines the thread's anti-extrusion performance and gas-tightness. The thread tooth height also affects the quality and efficiency of the threaded connection. Due to the taper and angular characteristics of threads in space, there is currently a lack of rapid measurement methods for the corresponding thread pitch diameter and tooth height parameters in the oil pipe industry, based on a three-coordinate measuring machine (CCM) standard. Summary of the Invention

[0007] One of the objectives of this invention is to provide a rapid measurement method for the dimensional parameters of internal pipe threads. This method is based on a three-coordinate thread measurement datum and can achieve rapid measurement of thread pitch diameter and tooth height parameters, which can be further applied in digital automatic measurement.

[0008] To achieve the above objectives, the present invention provides a rapid measurement method for the dimensional parameters of internal pipe threads, which is based on a coordinate measuring machine and includes the following steps:

[0009] 100: Establish a measurement coordinate system, where the origin O of the measurement coordinate system is the intersection of the axial end face of the pipe and the central axis of the pipe, the Z-axis of the measurement coordinate system coincides with the central axis of the pipe, and the X-axis and Y-axis of the measurement coordinate system point to the radial direction of the pipe.

[0010] 200: Move the probe of the coordinate measuring device from the origin of the measuring coordinate system along the Z-axis to the measuring surface. On the measuring surface, the probe makes contact points on the inner wall of the tube along the circumferential direction of the tube, obtaining n contact points evenly distributed in the circumferential direction. Record the distance from each contact point to the Z-axis to obtain n measurement values; where n≥n0, and n0 is the minimum number of contact points to ensure that at least one contact point falls on the root and tip of the internal thread respectively.

[0011] 300: The tooth height, tooth tip diameter, and tooth root diameter of the internal thread are calculated based on several measured values.

[0012] Furthermore, the rapid measurement method for the internal thread size parameters of the pipe described in this invention also includes step 400: calculating the mean diameter of the internal thread based on the tip diameter and root diameter of the internal thread.

[0013] Furthermore, in step 400 of the rapid measurement method for the dimensional parameters of the internal thread of the pipe described in this invention, the pitch diameter D of the internal thread is calculated based on the following formula:

[0014] D = (D1 + D2) / 2 - 2 × (h2 - h1)

[0015] Where h1 and h2 are the nominal tooth tip height and nominal tooth root height of the internal thread, respectively, D1 is the tooth tip diameter of the internal thread, and D2 is the tooth root diameter of the internal thread.

[0016] Furthermore, in step 300 of the rapid measurement method for the dimensional parameters of the internal thread of the pipe described in this invention, the tooth height h of the internal thread is calculated based on the following formula:

[0017] h = max(r1, r2, ..., r) n )-min(r1, r2, ..., r n )

[0018] Where r1, r2, ..., r n Let n represent n measured values, min represents finding the minimum value of the n measured values, and max represents finding the maximum value of the n measured values.

[0019] Furthermore, in step 300 of the rapid measurement method for the internal thread dimensional parameters of the pipe described in this invention, the internal thread tooth tip diameter D1 is calculated based on the following formula:

[0020] D1 = 2 × min(r1, r2, ..., r n )

[0021] Where r1, r2, ..., r n Let represent n measured values, and min represents finding the minimum value among the n measured values.

[0022] Furthermore, in step 300 of the rapid measurement method for the internal thread dimensional parameters of the pipe described in this invention, the internal thread root diameter D2 is calculated based on the following formula:

[0023] D2 = 2 × max(r1, r2, ..., r n )

[0024] Where r1, r2, ..., r n Let represent n measured values, and max represents finding the maximum value among the n measured values.

[0025] Furthermore, in the rapid measurement method for the internal thread dimensional parameters of the pipe described in this invention, the minimum number of contact points n0 is calculated based on the following formula:

[0026]

[0027] Where P represents the pitch, L1 represents the axial length of the straight segment at the tooth tip, L2 represents the axial length of the straight segment at the tooth root, and min represents finding the minimum value. This indicates rounding up to the nearest integer.

[0028] Furthermore, in the rapid measurement method for the internal thread dimensional parameters of the pipe described in this invention, the coordinate measuring device is a coordinate measuring machine.

[0029] Furthermore, in the rapid measurement method for the internal thread dimensional parameters of the pipe described in this invention, the coordinate measuring device is a comparator.

[0030] Compared with existing technologies, the rapid measurement method for the pitch diameter and tooth height of pipe internal threads described in this invention has the following advantages and beneficial effects:

[0031] The rapid measurement method for pitch diameter and tooth height of internal pipe threads described in this invention enables rapid measurement of the pitch diameter and tooth height parameters of internal oil pipe threads under a three-coordinate system. Furthermore, after solving the method for establishing a coordinate system for measuring internal oil pipe threads, it can be further promoted in digital automatic measurement. Attached Figure Description

[0032] Figure 1 The basic structure of the internal thread of an oil pipe is shown.

[0033] Figure 2 A schematic diagram of the tooth profile for a single-pitch internal thread design is shown.

[0034] Figure 3 A schematic diagram showing the measurement of the thread pitch diameter is displayed.

[0035] Figure 4 A schematic diagram of the plane section for measuring the mean diameter of a thread is shown. Detailed Implementation

[0036] The following description, based on specific embodiments and accompanying drawings, further illustrates the rapid measurement method for the tooth height of the inner diameter of pipe threads according to the present invention. However, this description does not constitute an improper limitation of the present invention.

[0037] In some embodiments, a rapid measurement method for the dimensional parameters of pipe internal threads, based on a coordinate measuring machine, may include the following steps:

[0038] 100: Establish a measurement coordinate system, where the origin O of the measurement coordinate system is the intersection of the axial end face of the pipe and the central axis of the pipe, the Z-axis of the measurement coordinate system coincides with the central axis of the pipe, and the X-axis and Y-axis of the measurement coordinate system point to the radial direction of the pipe.

[0039] In some more specific embodiments, the coordinate measuring device can be a coordinate measuring machine. In other more specific embodiments, the coordinate measuring device can also be a comparator.

[0040] 200: Move the probe of the coordinate measuring device from the origin of the measuring coordinate system along the Z-axis to the measuring surface. On the measuring surface, the probe makes contact points on the inner wall of the tube along the circumferential direction of the tube, obtaining n contact points evenly distributed in the circumferential direction. Record the distance from each contact point to the Z-axis to obtain n measurement values; where n≥n0, and n0 is the minimum number of contact points to ensure that at least one contact point falls on the root and tip of the internal thread respectively.

[0041] In some specific implementations, the minimum number of contact dots n0 can be calculated based on the following formula:

[0042]

[0043] Where P represents the pitch, L1 represents the axial length of the straight segment at the tooth tip, L2 represents the axial length of the straight segment at the tooth root, and min represents finding the minimum value. This indicates rounding up to the nearest integer.

[0044] In some specific implementations, in the measurement coordinate system, the probe moves from the origin along the negative Z-axis to the distance L between the mid-diameter and the end face. Then, in the XY plane, it makes contact points relative to the X-axis along the 0, 2π / n, ..., 2π(n-1) / n radian directions, thereby recording the distance from the contact point to the mid-axis Z-axis.

[0045] 300: such as Figure 3 and Figure 4 As shown, the tooth height, tooth tip diameter, and tooth root diameter of the internal thread can be calculated based on several measured values.

[0046] In some specific implementations, the tooth height h of the internal thread is calculated based on the following formula:

[0047] h = max(r1, r2, ..., r) n )-min(r1, r2, ..., r n )

[0048] Where r1, r2, ..., r n Let n represent n measured values, min represents finding the minimum value of the n measured values, and max represents finding the maximum value of the n measured values.

[0049] In some specific implementations, the internal thread tooth tip diameter D1 is calculated based on the following formula:

[0050] D1 = 2 × min(r1, r2, ..., r n )

[0051] Where r1, r2, ..., r n Let represent n measured values, and min represents finding the minimum value among the n measured values.

[0052] In some specific implementations, the internal thread root diameter D2 is calculated based on the following formula:

[0053] D2 = 2 × max(r1, r2, ..., r n )

[0054] Where r1, r2, ..., r n Let represent n measured values, and max represents finding the maximum value among the n measured values.

[0055] In some implementations, step 400 may also be included: calculating the mean diameter of the internal thread based on the tip diameter and root diameter of the internal thread.

[0056] In some specific implementations, the pitch diameter D of the internal thread is calculated based on the following formula:

[0057] D = (D1 + D2) / 2 - (h2 - h1)

[0058] Where h1 and h2 are the nominal tooth tip height and nominal tooth root height of the internal thread, respectively, D1 is the tooth tip diameter of the internal thread, and D2 is the tooth root diameter of the internal thread.

[0059] The present invention also provides a specific embodiment to further illustrate the rapid measurement method for the pitch diameter tooth height of pipe internal threads described herein.

[0060] Figure 1 This shows the basic structure of the internal thread of an oil pipe. (Example) Figure 1 As shown, the outer circumferential surface of the oil pipe is the outer wall 3, and along the axial direction from its axial end face 1, its inner circumferential surface has a threaded section 2, a transition section 4, a sealing section 5, a shoulder surface 6, and an inner through hole 7.

[0061] Figure 2 A schematic diagram of the tooth profile for a single-pitch internal thread design is shown.

[0062] like Figure 2 As shown, considering factors such as design fit, the root height h2 of an internal thread is usually greater than the tip height h1.

[0063] In a specific example, the rapid measurement of the pitch diameter and tooth height of the internal thread of a BGT3 thread type with an outer diameter of 88.90 mm and a wall thickness of 6.45 mm may include the following steps:

[0064] (1) As Figure 3 As shown, a measurement coordinate system is established, where the origin O of the measurement coordinate system is the intersection of the axial end face of the pipe and the central axis of the pipe, the Z-axis of the measurement coordinate system coincides with the central axis of the pipe, and the X-axis and Y-axis of the measurement coordinate system point to the radial direction of the pipe.

[0065] (2) Figure 3 As shown, in the measuring coordinate system, the probe moves from the origin along the negative Z-axis to the distance L between the pitch diameter and the end face. The axial length of the straight section at the tooth tip, L1 = 1.6212 mm, the axial length of the straight section at the tooth root, L2 = 1.3017 mm, and P = 4.2333 mm can be calculated. Let n be 4. Therefore, contact points are made in the XY plane relative to the X-axis along the directions of 0, π / 2, π, and 3π / 2 radians, respectively, to obtain four horizontal measurement values, which are denoted as r1, r2, r3, and r4. Figure 4 A schematic diagram of the plane section for measuring the mean diameter of a thread is shown.

[0066] (3) It can be obtained that:

[0067] The internal thread tip diameter D1 = 2 × min(r1,r2,...,r4) = 87.166 mm;

[0068] The diameter of the internal thread root, D2, is 2 × max(r1,r2,...,r4) = 89.570 mm;

[0069] Tooth height h = max(r1,r2,...,r4) - min(r1,r2,...,r4) = 1.202mm.

[0070] The mean diameter of the internal thread is D = (D1 + D2) / 2 - (h2 - h1) = 88.168 mm, where h1 and h2 are the nominal tooth tip height and nominal tooth root height of the internal thread, respectively, h1 = 0.5 mm and h2 = 0.7 mm.

[0071] Therefore, the method described in this invention can achieve rapid measurement of thread pitch diameter and tooth height parameters based on the thread measurement datum under three coordinates, and can be further applied in digital automatic measurement.

[0072] It should be noted that the scope of protection of the prior art in this invention is not limited to the embodiments given in this application. All prior art that does not contradict the solution of this invention, including but not limited to prior patent documents, prior publications, prior public uses, etc., can be included in the scope of protection of this invention.

[0073] Furthermore, the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0074] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A rapid measurement method for the dimensional parameters of internal pipe threads, which is based on a coordinate measuring machine, characterized in that, Including the following steps: 100: Establish a measurement coordinate system, where the origin O of the measurement coordinate system is the intersection of the axial end face of the pipe and the central axis of the pipe, the Z-axis of the measurement coordinate system coincides with the central axis of the pipe, and the X-axis and Y-axis of the measurement coordinate system point to the radial direction of the pipe. 200: Move the probe of the coordinate measuring device from the origin of the measuring coordinate system along the Z-axis to the measuring surface. On the measuring surface, the probe makes contact points on the inner wall of the tube along the circumferential direction of the tube, obtaining n contact points evenly distributed in the circumferential direction. Record the distance from each contact point to the Z-axis to obtain n measurement values; where n≥n0, and n0 is the minimum number of contact points to ensure that at least one contact point falls on the root and tip of the internal thread respectively. 300: The tooth height, tooth tip diameter, and tooth root diameter of the internal thread are calculated based on several measured values.

2. The rapid measurement method for the dimensional parameters of the internal thread of a pipe as described in claim 1, characterized in that, It also includes step 400: calculating the mean diameter of the internal thread based on the tip diameter and root diameter of the internal thread.

3. The rapid measurement method for the dimensional parameters of the internal thread of a pipe as described in claim 2, characterized in that, In step 400, the pitch diameter D of the internal thread is calculated based on the following formula: D = (D1 + D2) / 2 - 2 × (h2 - h1) Where h1 and h2 are the nominal tooth tip height and nominal tooth root height of the internal thread, respectively, D1 is the tooth tip diameter of the internal thread, and D2 is the tooth root diameter of the internal thread.

4. The rapid measurement method for the dimensional parameters of the internal thread of a pipe as described in claim 1 or 2, characterized in that, In step 300, the tooth height h of the internal thread is calculated based on the following formula: h=max(r1,r2,...,r n )-min(r1,r2,...,r n ) Where r1, r2, ..., r n Let n represent n measured values, min represents finding the minimum value of the n measured values, and max represents finding the maximum value of the n measured values.

5. The rapid measurement method for the dimensional parameters of the internal thread of a pipe as described in claim 1 or 2, characterized in that, In step 300, the internal thread tooth tip diameter D1 is calculated based on the following formula: D1=2×min(r1,r2,...,r n ) Where r1, r2, ..., r n Let represent n measured values, and min represents finding the minimum value among the n measured values.

6. The rapid measurement method for the dimensional parameters of the internal thread of a pipe as described in claim 1 or 2, characterized in that, In step 300, the internal thread root diameter D2 is calculated based on the following formula: D2=2×max(r1,r2,...,r n ) Where r1, r2, ..., r n Let represent n measured values, and max represents finding the maximum value among the n measured values.

7. The rapid measurement method for the dimensional parameters of the internal thread of a pipe as described in claim 1, characterized in that, The minimum number of contact dots n0 is calculated based on the following formula: Where P represents the pitch, L1 represents the axial length of the straight segment at the tooth tip, L2 represents the axial length of the straight segment at the tooth root, and min represents finding the minimum value. This indicates rounding up to the nearest integer.

8. The rapid measurement method for the dimensional parameters of the internal thread of a pipe as described in claim 1, characterized in that, The coordinate measuring device is a coordinate measuring machine.

9. The rapid measurement method for the dimensional parameters of the internal thread of a pipe as described in claim 1, characterized in that, The coordinate measuring device is a comparator.

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