System and method for measuring complex molded surface in long pipe

Abstract

The invention belongs to the technical field of precision measurement of an inner cavity of a slender tube, and particularly relates to a system and a method for measuring a complex profile in a long tube, and the system comprises an automatic centering mechanism, the automatic centering mechanism is connected with an angular displacement sensor, and the angular displacement sensor is connected with a rear fixed support through an angular displacement sensor support. The angular displacement sensor is connected with the laser sensor assembly, the laser sensor assembly comprises a laser sensor, the laser sensor is connected with the mandrel through a laser sensor seat, the automatic centering mechanism comprises an outer sleeve, and the mandrel is connected with the angular displacement sensor and can rotate in the outer sleeve; the angular displacement sensor comprises an angular displacement reading head, the laser sensor and the angular displacement reading head are respectively connected with a data acquisition device through cables, and the data acquisition device is connected with a computer through a cable; the laser sensor is adopted, the device can adapt to the shapes of the inner walls of different long pipes, the measurement precision is high, and the pipe walls are not scratched; the self-centering mechanism can achieve high-precision centering and is wide in application range.

Description

Technical Field

[0001] The present invention relates to the technical field of precise measurement of the inner cavity of slender tubes, and specifically to a measurement system and method for the complex inner surface of a long tube body. Background Art

[0002] During the use of various long tube body parts such as gun barrels, stator of screw drill tools, and stator of screw pumps, due to factors such as wear, the dimensions of their internal complex surfaces will change, and damages such as corrosion and scratches will occur. Therefore, in aspects such as the processing precision measurement, defect detection, wear detection, and life prediction of long tube bodies, it is necessary to measure the complex internal contours of long tube bodies to evaluate whether the dimensions meet the technical specification requirements and analyze the changes in the dimensions of the internal complex surfaces after a period of use. Compared with the measurement of the inner cavity of general pipelines, the measurement of long tube body parts mainly has the following difficulties:

[0003] 1. The inner wall of the long tube body is narrow and long, making it difficult for the human eye to observe; 2. The inner cavity of the long tube body is generally relatively small, making it difficult for common measuring instruments and tools to enter, and it is difficult to carry out measurement work; 3. The internal surfaces of the long tube body mainly include smooth surfaces, smooth spiral surfaces (stator of screw pumps), and keyway spiral surfaces (rifling in gun barrels), and general instruments are difficult to adapt to the measurement requirements of different inner wall surfaces.

[0004] Currently, the measurement of the complex internal surfaces of long tube bodies at home and abroad mainly adopts mechanical measurement methods and optical measurement methods, and corresponding measuring equipment is used respectively. Mechanical measuring equipment adopts contact measurement methods, mainly including go-no-go gauges, internal micrometers, and internal dial indicators. Among them, go-no-go gauges are used for qualitative measurement, while the measurement depth of internal micrometers and internal dial indicators is limited.

[0005] Optical inner cavity measuring equipment based on triangulation technology and optical displacement sensors is currently a relatively common precise optical measuring equipment for the inner cavity of slender tubes. These measuring equipment all adopt non-contact measurement methods, and a large number of optical components with almost all length and width dimensions in the order of dozens of millimeters, such as lasers, collimating lenses, CCD (or CMOS), and optical displacement sensors, need to be compactly installed in the measuring head inner cavity. Since the measured diameter results are related to parameters such as the placement angle of the collimating lens and the mutual distance between lens groups, these parameters need to be precisely calibrated after installation. The existing measurement methods are difficult to achieve precise centering of the instrument inside the long tube body, resulting in low accuracy of the measurement results.

[0006] In summary, in the measurement of the complex internal surfaces of long tube bodies, the precise centering of the instrument is the key to ensuring the measurement accuracy of the system and is also the key research direction of scientific research personnel in this field.

[0007] In the document with the publication number: CN 106225701 A and the title: A Measuring Device and Method for the Inner Cavity of a Smooth Bore Long Barrel with a Small Bore Diameter, a centering mechanism is disclosed: The first set of centering feet is installed from the inside of the centering mechanism body into the through hole on the side of the centering mechanism body. The conical surface of the first conical slider fits with the hemispherical surface at the bottom end of the first set of centering feet; One side of the bottom end surface of the first conical slider is provided with a first spring; On the other side of the first spring, a separator plate that presses the first spring is placed. The threaded hole of the separator plate is aligned with the through hole of the mechanism body, and the threaded hole of the separator plate and the through hole of the mechanism body are fixedly connected with a set screw; Then, a second spring and a second conical slider are placed in sequence, and the second set of centering feet is installed from the inside of the mechanism body into the through hole on the side of the mechanism body; The conical surface of the second conical slider fits with the hemispherical surface at the bottom end of the second set of centering feet; Finally, the rear cover is tightened to complete the installation of the centering mechanism.

[0008] In the document with the publication number: CN 103021484 B; and the title: An Automatic Centering Mechanism for a Nuclear Power Plant Safety-Type Pipeline, an automatic centering mechanism for a nuclear power plant safety-type pipeline is disclosed, which includes a central rod capable of carrying a detection instrument; A plurality of groups of support components distributed at intervals around the central rod, each group of the support components includes a first support rod and a second support rod that are rotatably connected to each other: A fixed seat fixedly arranged on the central rod: A sliding seat that can slide along the longitudinal direction of the central rod on the central rod. The first support rod of each group of support components is rotatably connected to the fixed seat, and one end of the second support rod of each group of support components is rotatably connected to the sliding seat. Rollers capable of pressing against the inner wall of the pipeline to be inspected are arranged at the ends of the first support rod and the second support rod of each group of support components. The axis of rotation of the rotational connection between the first support rod and the second support rod in each group of support components, the axis of rotation of the rotational connection between the first support rod and the fixed seat, and the axis of rotation of the rotational connection between the second support rod and the sliding seat are parallel and extend along the transverse direction of the central rod.

[0009] The centering mechanism of the above invention realizes the automatic centering of the centering mechanism for the inner surface of the pipe to be measured by two groups of three-point centering or multi-point support centering. There is a problem that the radial dimensions of the feet or each support point of the multi-point support are different, resulting in eccentricity in such a centering structure, that is, it is impossible to accurately position a smooth spiral surface or a keyway-type spiral surface. Therefore, the above structure is only applicable to the centering of the inner hole of a smooth barrel and cannot accurately center on a non-smooth surface, making it difficult to meet the centering requirements for measuring complex profiles inside a long barrel. Summary of the Invention

[0010] The purpose of the present invention is to provide a measuring system and method for complex profiles inside a long barrel to solve the problems raised in the above background technology.

[0011] To achieve the above object, the present invention provides the following technical solution: A measuring system for the complex internal surface of a long barrel, including an automatic centering mechanism. The automatic centering mechanism includes a mandrel and an outer sleeve arranged concentrically, a support connecting rod, and a guiding shoe. The mandrel is connected to an angular displacement sensor and can rotate within the outer sleeve. The automatic centering mechanism is connected to a data acquisition device through a cable, and the data acquisition device is connected to a computer through a cable. The automatic centering mechanism is connected to the angular displacement sensor, and the angular displacement sensor is connected to a rear fixed support through an angular displacement sensor bracket. The angular displacement sensor is connected to a laser sensor assembly, and the laser sensor assembly includes a laser sensor. The laser sensor is connected to the mandrel through a laser sensor seat.

[0012] Preferably: The automatic centering mechanism includes a bearing and an outer sleeve, and a spring is arranged inside the outer sleeve. The mandrel is rotationally connected to the outer sleeve through the bearing, and the outer sleeve is respectively provided with a sliding support and a fixed support. The sliding support, the fixed support, and the support connecting rod are evenly distributed along the circumference with an adjacent interval of 120°, and are rotationally connected to the support connecting rod. The mandrel and the extension rod are connected by a universal joint at the tail.

[0013] Preferably: The angular displacement sensor includes an angular displacement sensor bracket, an angular displacement sensor code disk, and an angular displacement reading head. The angular displacement reading head is connected to the angular displacement sensor bracket connected to the outer sleeve through a thread. The angular displacement sensor code disk is connected to the mandrel, and the angular displacement sensor bracket is connected to the outer sleeve.

[0014] Preferably: A rear fixed support is arranged on the outer sleeve, and the rear fixed support is connected to the angular displacement sensor bracket.

[0015] Preferably: The guiding shoe is rotationally connected to the sliding support and the fixed support through the support connecting rod. The support connecting rods respectively hinged to the fixed support and the rear fixed support always remain parallel. The support connecting rod, the guiding shoe, and the outer sleeve form a parallelogram mechanism.

[0016] Preferably: The laser sensor is connected to the laser sensor seat through a laser sensor bracket, and the laser sensor seat is connected to the laser sensor through a positioning structure. The laser sensor seat is connected to the mandrel, and a positioning nut is arranged on the laser sensor seat.

[0017] Preferably: An adjusting nut is arranged between the outer sleeve and the mandrel for adjusting the contact pressure between the guiding shoe and the complex internal surface of the long barrel.

[0018] According to the measurement method of the internal complex surface measurement system for a long barrel described above, the following steps are included: After adjusting the positions where the sliding support and the laser sensor need to be radially offset according to the inner cavity size of the long barrel to be measured, install this system into the inner cavity of the long barrel to be measured, and rotate the core shaft, thereby driving the laser sensor and the angular displacement sensor to rotate. The laser sensor measures the radial distance at the current position, and the angular displacement sensor determines the angle of the circumferential position. By rotating one week, the radial dimensions of the current cross-section can be measured. Manually operate the extension rod to adjust the position of the measuring device in the long barrel, and the radial dimensions of any cross-section can be measured; the measurement and counting data directly come from the radial measurement value of the laser sensor and the rotation angle measurement value of the angular displacement sensor, and are displayed on the computer after being processed by the data acquisition device.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) The present invention uses a laser sensor, which can adapt to the inner wall morphologies of different long barrels, has high measurement accuracy, and does not scratch the pipe wall. The laser sensor is connected to the laser sensor seat through a positioning structure, and the position of the laser sensor is adjusted by adjusting the positioning nut on the laser sensor seat to meet the inner diameter measurement requirements of different types of long barrels;

[0021] (2) The self-centering mechanism of the present invention adopts three groups of parallelogram mechanisms, which can achieve high-precision centering functions. For internal complex surface types with spiral grooves, such as the stator of a positive displacement motor and the stator of a screw pump, the length of the guiding shoe of the centering mechanism is greater than twice the pitch of the spiral groove. Each guiding shoe has at least 3 points of contact with the internal complex surface of the long barrel, avoiding the suspension of the contact position between the guiding shoe and the inner surface of the internal complex surface of the long barrel, and ensuring that this system can accurately center all internal complex surfaces of the long barrel;

[0022] (3) The self-centering mechanism of the present invention has a wide range of applications, can adapt to smooth inner wall surfaces, and can also adapt to different spiral surfaces. After adjusting the positions where the sliding support and the laser sensor need to be radially offset according to the inner cavity size of the long barrel to be measured, install this system into the inner cavity of the long barrel to be measured, and rotate the core shaft, thereby driving the laser sensor and the angular displacement sensor to rotate. The laser sensor measures the radial distance at the current position, and the angular displacement sensor determines the angle of the circumferential position. By rotating one week, the radial dimensions of the current cross-section can be measured. Manually operate the extension rod to adjust the position of the measuring device in the long barrel, and the radial dimensions of any cross-section can be measured. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the self-centering mechanism of the present invention;

[0024] Figure 2 It is a schematic diagram of the measurement state of the internal complex surface of the long barrel of the present invention;

[0025] Figure 3 Cross-sectional view of the device according to an embodiment of the present invention;

[0026] Figure 4 Schematic structural diagram of the present invention;

[0027] Figure 5 Schematic structural diagram of the angular displacement sensor of the present invention;

[0028] Figure 6 Schematic structural diagram of the laser sensor assembly of the present invention.

[0029] In the figure, 101 is the mandrel, 102 is the outer sleeve, 103 is the spring, 104 is the sliding support, 105 is the fixed support, 106 is the support link, 107 is the guiding shoe, 108 is the rear fixed support, 109 is the extension rod, 111 is the adjusting nut, 203 is the angular displacement sensor, 201 is the angular displacement sensor bracket, 202 is the angular displacement reading head, 203 is the angular displacement sensor code disk, 301 is the laser sensor seat, 302 is the laser sensor bracket, 303 is the laser sensor, 4 is the data acquisition device, 5 is the computer, and 6 is the complex inner surface of the long barrel. Specific embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] The present invention is a measurement system for the complex inner surface of a long barrel. Refer to Figure 1 and Figure 4 , the automatic centering mechanism includes a mandrel 101, a laser sensor 303, an angular displacement sensor 203, an extension rod 109, etc. The mandrel 101 is connected to the laser sensor 303 and the angular displacement sensor 203 and can rotate within the outer sleeve 102. The automatic centering mechanism is connected to the angular displacement sensor 203. The laser sensor 303 is connected to the laser sensor seat 301 through the laser sensor bracket 302, and the laser sensor 303 is connected to the mandrel 101 through the laser sensor seat 301. The laser sensor 303 and the angular displacement reading head 202 are respectively connected to the data acquisition device 4 through cables, and the data acquisition device 4 is connected to the computer 5 through a cable.

[0032] Refer to Figure 1, the automatic centering mechanism 100 includes an outer sleeve 102, a spring 103, a sliding support 104, a fixed support 105, a rear fixed support 108, a support link 106, a guiding shoe 107, etc. The mandrel 101 is rotatably connected to the outer sleeve 102 through a bearing 110, and a spring 103 is arranged inside the outer sleeve 102. The end of the mandrel 101 is connected to an extension rod 109. The outer sleeve 102 is respectively provided with a sliding support 104, a fixed support 105, and a rear fixed support 108. The fixed support 105, the rear fixed support 108, and the sliding support 104 are respectively provided with the support links 106 that are rotatably connected and evenly distributed along a 120-degree circumference. The guiding shoe 107 is rotatably connected to the support link 106. The angular displacement sensor bracket 201 and the laser sensor seat 301 are respectively connected to the outer sleeve 102 and the mandrel 101 and are respectively connected to the angular displacement sensor 203 and the laser sensor 303. A parallelogram link mechanism composed of the support link 106 and the guiding shoe 107 is provided on the outer sleeve 102, and the support link 106 and the guiding shoe 107 are evenly distributed at intervals of 120 degrees in the circumferential direction. According to the known inner cavity size of the long barrel to be measured, the axial displacement of the sliding support 104 and the radial eccentric position of the laser sensor 303 can be adjusted. By rotating the mandrel 360 degrees, the laser sensor completes a full-circle scan, thereby collecting complete cross-sectional measurement data. An adjusting nut 111 is arranged between the outer sleeve 102 and the mandrel 101, and the pressure of the guiding shoe 107 in contact with the complex inner surface 6 of the long barrel can be adjusted through the adjusting nut 111.

[0033] See Figure 5 , the angular displacement sensor 203 includes an angular displacement sensor bracket 201, an angular displacement sensor code disk 203, and an angular displacement reading head 202. The angular displacement reading head 202 is connected to the angular displacement sensor bracket 201 connected to the outer sleeve 102 through a thread, and the angular displacement sensor code disk 203 is connected to the mandrel 101.

[0034] See Figure 6 , the laser sensor 303 is connected to the laser sensor seat 301 through a positioning structure, and the position of the laser sensor 303 can be adjusted by adjusting the positioning nut on the laser sensor seat 301, so as to meet the measurement of the inner cavities of different models of long barrels.

[0035] Correspondingly, the present invention also provides a method for measuring the complex inner surface of a long barrel. The measurement and counting data directly come from the radial measurement value of the laser sensor and the rotation angle measurement value of the angular displacement sensor, and are displayed on a computer after being processed by a data acquisition device.

[0036] See Figure 2 and Figure 3, during use, after adjusting the sliding support 104 and the radially offset position of the laser sensor according to the inner cavity size of the long barrel to be measured, the system is installed into the inner cavity of the long barrel to be measured. Then, rotate the core shaft 101, which drives the laser sensor 303 and the angular displacement sensor 203 to rotate. The laser sensor 303 measures the radial distance at the current position, and the angular displacement sensor 203 determines the angle of the circumferential position. By rotating one full circle, the radial dimensions of the current cross-section can be measured. Manually operate the extension rod 109 to adjust the position of the measuring device in the long barrel, and the radial dimensions of any cross-section can be measured.

[0037] Embodiment 1

[0038] As Figure 4 shown, a measuring system for the complex inner surface of a long barrel provided in this embodiment includes three groups of automatic centering mechanisms, a core shaft 101, an angular displacement sensor 203, a laser sensor assembly 3, a data acquisition device 4, and a computer 5. The laser sensor assembly 3 is connected to the core shaft 101, the angular displacement sensor 203 is connected to the automatic centering mechanism, and the code disk of the angular displacement sensor 203 is connected to the core shaft 101. The data acquisition device 4 is connected to the laser sensor 303, the angular displacement sensor 203, and the computer 5 through cables.

[0039] As Figure 1 shown, the automatic centering mechanism includes an outer sleeve 102, a spring 103, a sliding support 104, a fixed support 105, a support link 106, a guiding shoe 107, and a rear fixed support 108. The core shaft 101 is rotationally connected to the outer sleeve 102 through a bearing 110. The outer sleeve is respectively provided with a sliding support 104, a fixed support 105, and a rear fixed support 108. The fixed support 105, the sliding support 104, and the rear fixed support 108 are evenly arranged and connected along the circumference at intervals of 120° with the support link 106. The guiding shoe 107 is rotationally connected to the support link 106. The angular displacement sensor 203 is connected to the rear fixed support 108, and the laser sensor 303 is connected to the core shaft 101.

[0040] During use, after rotating and adjusting the adjusting nut 111 and the radially offset position of the laser sensor 303 according to the inner cavity size of the long barrel to be measured, the system is installed at the position of the cross-section size to be measured in the inner cavity of the long barrel to be measured. Rotate the core shaft 101, the laser sensor 303 measures the radial distance of the inner wall of the long barrel, and the angular displacement sensor 203 measures the circumferential angle, thereby realizing the profile measurement of the cross-section.

[0041] Embodiment 2

[0042] As Figure 2 and Figure 3As shown in the figure, in this embodiment, for the internal complex surface with spiral grooves, such as the stator of a positive displacement motor and the stator of a screw pump, the length of the centering mechanism guide shoe 107 is greater than twice the pitch of the spiral groove. Each guide shoe 107 has at least three points of contact with the internal complex surface 6 of the long body tube, avoiding the suspension of the contact position between the guide shoe 107 and the inner surface of the internal complex surface 6 of the long body tube, and ensuring that the system can accurately center all the internal complex surfaces of the long body tube.

[0043] such as Figure 6 As shown in the figure, in this embodiment, the laser sensor seat 301 is connected to the laser sensor bracket 302, and the position of the laser sensor 303 on the laser sensor bracket 302 can be adjusted by adjusting the positioning nut. When measuring the inner cavity of long body tubes with different inner diameters, according to the inner diameter size of the internal complex surface 6 of the long body tube to be measured, the offset position of the laser sensor bracket 302 is adjusted by adjusting the positioning nut on the laser sensor seat 301 to ensure that the measured cross-sectional contour is always within the measurement range of the laser sensor 303.

[0044] Among them, the positioning structure can adopt well-known technologies.

[0045] In addition, after the automatic centering mechanism is installed into the internal complex surface 6 of the long body tube to be measured, under the action of the self-centering mechanism, the axis of the mandrel 101 coincides with the axis of the inner cavity of the long body tube. Among them, the rotation of the mandrel 101 can be manually rotated or by a stepper motor with a reducer.

[0046] In this embodiment, during use, the extension rod 109 is connected to the tail of the mandrel 101. After the automatic centering mechanism is sent into the internal complex surface 6 of the long body tube to be measured through the extension rod 109, under the pre-tightening force of the spring 103, the three groups of circumferential guide shoes 107 are in reliable contact with the inner wall of the stator, making the center of the whole device coincide with the center of the inner cavity of the long body tube. After rotating the mandrel 101, the laser sensor 303 rotates and scans in the automatic centering mechanism along with the mandrel 101. During the scanning process, the laser sensor 303 measures the radial distance of the tube wall, and the angular displacement reading head 202 measures the circumferential angular position.

[0047] Corresponding to the above embodiment, this embodiment provides a method for measuring the inner cavity of a long body tube using the above system. The measurement data of the inner diameter of the long body tube comes from the radial measurement value and offset of the laser sensor and the angular measurement value of the angular displacement sensor, and is displayed on a computer after being processed by a data acquisition device.

[0048] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0049] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for measuring complex internal surfaces of a long barrel, including an automatic centering mechanism, characterized in that: The automatic centering mechanism comprises a core shaft (101) and an outer sleeve (102) which are arranged concentrically, a supporting connecting rod (106), and a guide shoe (107); the core shaft (101) is connected to an angular displacement sensor (203) and can rotate in the outer sleeve (102); the automatic centering mechanism is connected to a data acquisition device (4) via a cable, and the data acquisition device (4) is connected to a computer (5) via a cable; the automatic centering mechanism is connected to the angular displacement sensor (203), and the angular displacement sensor (203) is connected to a rear fixed support (108) via an angular displacement sensor bracket (201); the angular displacement sensor is connected to a laser sensor assembly, and the laser sensor assembly comprises a laser sensor (303), and the laser sensor (303) is connected to the core shaft (101) via a laser sensor seat (301).

2. A system for measuring complex internal surfaces of a long barrel according to claim 1, characterized in that: The automatic centering mechanism comprises a bearing (110) and an outer sleeve (102), and a spring (103) is arranged inside the outer sleeve (102); the core shaft (101) is rotatably connected to the outer sleeve (102) via the bearing (110), and the outer sleeve (102) is respectively provided with a sliding support (104) and a fixed support (105); the sliding support (104), the fixed support (105) and the supporting connecting rod (106) are evenly distributed at 120 degrees along the circumferential direction and are respectively rotatably connected to the supporting connecting rod (106); the core shaft (101) and the extension rod (109) are connected at the tail by a universal shaft.

3. A system for measuring complex internal surfaces of a long barrel according to claim 2, characterized in that: The angular displacement sensor comprises an angular displacement sensor bracket (201), an angular displacement sensor code disc (203) and an angular displacement reading head (202), wherein the angular displacement reading head (202) is connected to the angular displacement sensor bracket (201) connected to an outer sleeve (102) via a thread, the angular displacement sensor code disc (203) is connected to a core shaft (101), and the angular displacement sensor bracket (201) is connected to the outer sleeve (102).

4. A system for measuring complex internal surfaces of a long barrel according to claim 3, characterized in that: A rear fixed support (108) is provided on the outer sleeve (102), and the rear fixed support (108) is connected to the angular displacement sensor bracket (201).

5. A system for measuring complex internal surfaces of a long barrel according to claim 4, characterized in that: The guide shoe (107) is connected to the sliding support (104) and the fixed support (105) through a supporting link (106), and the supporting link (106) is hinged to the fixed support (105) and the rear fixed support (108) respectively, and they always remain parallel to each other. The supporting link (106), the guide shoe (107) and the outer sleeve (102) form a parallelogram mechanism.

6. A system for measuring complex internal surfaces of a long barrel according to claim 5, characterized in that: The laser sensor (303) is connected to the laser sensor seat (301) via a laser sensor bracket (302), and the laser sensor seat (301) is connected to the laser sensor (303) via a positioning structure. The laser sensor seat (301) is connected to the core shaft (101), and a positioning nut is provided on the laser sensor seat (301).

7. A system for measuring complex internal surfaces of a long barrel according to claim 6, characterized in that: An adjusting nut (111) for adjusting the contact pressure between the guide shoe (107) and the complex internal surface (6) of the long barrel is arranged between the outer sleeve (102) and the core shaft (101).

8. A method for measuring a complex internal surface of a long barrel according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: after adjusting the radial displacement positions of the sliding support (104) and the laser sensor (303) according to the inner cavity size of the long barrel to be measured, the system is installed in the inner cavity of the long barrel to be measured, the core shaft (101) is rotated, thereby driving the laser sensor (303) and the angular displacement sensor (203) to rotate, the laser sensor (303) measures the radial distance of the current position, the angular displacement sensor (203) determines the angle of the circumferential position, and the radial size of the current cross section can be measured after one rotation, and the position of the measuring device in the long barrel is adjusted by manually operating the extension rod (109) to measure the radial size of any cross section; the measurement and counting data are directly derived from the radial measurement value of the laser sensor (303) and the rotation angle measurement value of the angular displacement sensor (203), and are displayed on a computer (5) after being processed by a data acquisition device (4).

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