A handheld laser rangefinder auxiliary fixing device for distance measurement in long pipelines

Abstract

This invention relates to auxiliary fixing devices, specifically to an auxiliary fixing device for handheld laser rangefinders used for measuring the length of long pipes. It addresses the problem that existing handheld laser rangefinders, when measuring the length of long pipes, often cause the emitted laser to deviate from the pipe's axis and strike the pipe wall due to handheld operation, leading to measurement failures or data inaccuracies. The first and second clamping arm assemblies of this invention form a linkage clamping mechanism through two sub-clamping arms and a connecting arm. This mechanism enables automatic centering and fixing of the handheld laser rangefinder placed on the base plate. Simultaneously, two tensioning components ensure stable clamping of handheld laser rangefinders of different sizes. By cooperating with the outer wall of the collimating cylinder and the inner wall of the long pipe being measured, the optical axis of the laser path of the handheld laser rangefinder is ensured to be coaxial with the central axis of the collimating cylinder. In long pipe distance measurement operations, this effectively prevents the laser from deviating from the axis and irradiating the pipe wall, thereby improving measurement efficiency and result reliability.

Description

Technical Field

[0001] This invention relates to auxiliary fixing devices, specifically to an auxiliary fixing device for a handheld laser rangefinder used for distance measurement in long pipelines. Background Technology

[0002] Handheld laser rangefinders are widely used in various engineering installation fields such as building construction, equipment manufacturing, and large-scale equipment construction due to their advantages of fast measurement speed, high accuracy, and convenient operation. However, when measuring long pipes exceeding 5 meters in length, handheld operation is prone to shaking, causing the handheld laser rangefinder to become unstable. This results in the emitted laser beam deviating from the pipe axis and striking the pipe wall, leading to measurement failure or data inaccuracy. This problem often forces operators to attempt measurements repeatedly, and in severe cases, it can even prevent the acquisition of accurate data, reducing measurement efficiency and affecting the reliability and convenience of engineering implementation. Therefore, there is an urgent need for an auxiliary device that can stably fix the handheld laser rangefinder and ensure that the laser beam is aligned with the pipe axis to improve the accuracy and efficiency of long pipe distance measurement. Summary of the Invention

[0003] The purpose of this invention is to solve the technical problem that when using existing handheld laser rangefinders to measure the length of long pipes, the emitted laser tends to deviate from the pipe axis and hit the pipe wall due to handheld operation, resulting in measurement failure or data deviation. The invention provides an auxiliary fixing device for handheld laser rangefinders used for measuring the distance of long pipes.

[0004] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0005] A handheld laser rangefinder auxiliary fixing device for long pipeline distance measurement is characterized by:

[0006] Includes a base, a collimating cylinder, a first clamping arm assembly, and a second clamping arm assembly;

[0007] The base is L-shaped and includes a base plate for placing a handheld laser rangefinder and a vertical plate vertically set at one end of the base plate; the vertical plate has a through hole in the center, the collimating cylinder is set at the mounting hole and located on the side away from the base plate, the outer wall of the collimating cylinder is used to fit with the inner wall of the long pipe to be measured, the inner hole is set to correspond to the laser emission port of the handheld laser rangefinder and the central axis of the inner hole is coaxial with the optical axis of the laser beam path;

[0008] The base plate is provided with a first guide groove, a first positioning pin hole, a second positioning pin hole and a second guide groove in sequence along its length direction, and the first guide groove is close to the end of the connecting vertical plate. The center lines of the four are all located in the mid-plane of the base plate through the central axis of the mounting hole.

[0009] The first clamping arm assembly and the second clamping arm assembly have the same structural size and are both located at the bottom of the base plate. They are symmetrically arranged with respect to the perpendicular bisector of the line connecting the center points of the first positioning pin hole and the second positioning pin hole. The first clamping arm assembly includes a tensioning component, two sub-clamping arms of the same structural size, and two connecting arms. The sub-clamping arms include a horizontal arm and a vertical arm vertically arranged on the horizontal arm. One end of the horizontal arm is connected to the vertical arm, and the other end is provided with a second docking pin hole. A first docking pin hole is also provided on the horizontal arm between the second docking pin hole and the vertical arm.

[0010] The two sub-clamping arms of the first clamping arm assembly are arranged vertically, and the second mating pin holes of the two arms correspond to the first positioning pin holes. The positioning pins pass through the two second mating pin holes in sequence and are hinged to the first positioning pin holes. The first mating pin holes of the two arms are respectively hinged to one end of the two connecting arms. The other end of the two connecting arms is hinged through a guide positioning pin, and the guide positioning pin is slidably arranged in the first guide groove. The tensioning component of the first clamping arm assembly is arranged on the base plate and connected to the corresponding guide positioning pin, and is used to pull the guide positioning pin to slide along the first guide groove.

[0011] The second docking pin holes of the two sub-clamping arms of the second clamping arm assembly are respectively hinged to the second positioning pin holes by positioning pins; the guide positioning pin is slidably set in the second guide groove, and the tensioning component is used to pull the guide positioning pin to slide along the second guide groove, so that the guide positioning pin of the first clamping arm assembly and the first clamping arm assembly move in opposite directions, and then the handheld laser rangefinder is clamped by the four vertical arms.

[0012] Furthermore, the tensioning assembly of the first clamping arm group includes a first tensioning screw. The base plate has a first through hole in the horizontal direction on the end face near the vertical plate. The first through hole is connected to the first guide groove. After the first tensioning screw passes through the first through hole, it is threadedly connected to the corresponding guide positioning pin. The inner side of the tail of the first tensioning screw abuts against the end face of the base plate.

[0013] The tensioning assembly of the second clamping arm group includes a second tensioning screw. The base plate has a second through hole in the horizontal direction on the end face away from the vertical plate. The second through hole is connected to the second guide groove. After the second tensioning screw passes through the second through hole, it is threadedly connected to the corresponding guide positioning pin. The inner side of the tail of the second tensioning screw abuts against the end face of the base plate.

[0014] Furthermore, the guide positioning pin has a second threaded hole that extends radially through it, and the first tensioning screw and the second tensioning screw are threadedly connected to the corresponding guide positioning pin through the second threaded hole.

[0015] Furthermore, the horizontal arm includes a first arm and a second arm, one end of the first arm is connected to one end of the second arm, and the first mating pin hole is provided at the connection position.

[0016] The second connecting pin hole is located at the other end of the first support arm, and the other end of the second support arm is connected to the vertical arm; there is an included angle A between the first support arm and the second support arm, and 120°≤A≤160°;

[0017] The included angle A of the horizontal arms of the two sub-clamping arms of the first clamping arm group faces the vertical plate side;

[0018] The included angle A of the horizontal arms of the two sub-clamping arms of the second clamping arm group faces the side far away from the vertical plate.

[0019] Furthermore, the vertical arm is a cylindrical structure with a first threaded hole at its center along the axial direction, and a clamping screw is screwed into the first threaded hole.

[0020] Furthermore, the mounting hole is a threaded hole, and the collimating cylinder includes a docking cylinder and a centering cylinder connected coaxially in sequence. The docking cylinder is threadedly engaged with the mounting hole, and the outer wall of the centering cylinder is used to engage with the inner wall of the long pipe to be measured.

[0021] Furthermore, the first arm and the second arm are integrally formed.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] (1) The present invention provides an auxiliary fixing device for a handheld laser rangefinder for long pipe distance measurement, comprising a base, a collimating cylinder, a first clamping arm group and a second clamping arm group. The first clamping arm group and the second clamping arm group have the same structure. The two sub-clamping arms and the connecting arm form a linkage clamping mechanism, which can realize the automatic centering and fixing of the handheld laser rangefinder. At the same time, the two tensioning components can realize the stable clamping of handheld laser rangefinders of different sizes, enhancing the versatility of the device. By the outer wall of the collimating cylinder cooperating with the inner wall of the long pipe to be measured, the optical axis of the laser path of the handheld laser rangefinder is ensured to be coaxial with the central axis of the collimating cylinder. In long pipe distance measurement operations, the laser can be effectively prevented from deviating from the axis and thus irradiating the pipe wall, thereby significantly improving the measurement efficiency and the reliability of the results.

[0024] (2) The collimating cylinder of the handheld laser rangefinder auxiliary fixing device for long pipe distance measurement provided by the present invention includes a docking cylinder and a centering cylinder connected coaxially in sequence. The docking cylinder is threadedly engaged with the mounting hole of the vertical plate to fix the entire collimating cylinder on the base. The outer wall of the centering cylinder is engaged with the inner wall of the long pipe to be measured. Different pipe inner diameters can be adapted by replacing the collimating cylinder of different specifications. This design not only facilitates on-site operation, but also expands the applicability of the device in different pipe diameter measurement scenarios.

[0025] (3) The present invention provides an auxiliary fixing device for a handheld laser rangefinder for measuring distance in long pipelines. The first arm and the second arm have an angle between them, which allows the guide positioning pin to move a shorter distance, so that the vertical arm can be closer to the base plate and the handheld laser rangefinder can be clamped faster, saving operation time. Attached Figure Description

[0026] Figure 1 This is a three-dimensional structural diagram of an embodiment of a handheld laser rangefinder auxiliary fixing device for long pipeline distance measurement according to the present invention. Figure 1 .

[0027] Figure 2 This is a three-dimensional structural diagram of an embodiment of the present invention. Figure 2 ;

[0028] Figure 3 This is a cross-sectional view of an embodiment of the present invention;

[0029] Figure 4 This is a three-dimensional structural diagram of the base in an embodiment of the present invention;

[0030] Figure 5 This is an exploded view of an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of an embodiment of the present invention in use.

[0032] The annotations in the attached figures are explained as follows:

[0033] 1-Base, 11-Base plate, 111-First guide groove, 112-Second guide groove, 113-First positioning pin hole, 114-Second positioning pin hole; 12-Vertical plate; 2-Alignment cylinder, 21-Diameter cylinder, 22-Centering cylinder; 3-First clamping arm assembly, 4-Second clamping arm assembly, 5-Sub-clamping arm, 51-Horizontal arm, 511-First support arm, 512-Second support arm; 52-Vertical arm, 6-Connecting arm, 7-Guide positioning pin, 8-Positioning pin, 9-First tensioning screw, 91-Second tensioning screw, 10-Pressure screw. Detailed Implementation

[0034] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0035] like Figures 1-6 As shown, this embodiment provides an auxiliary fixing device for a handheld laser rangefinder used for long pipeline distance measurement, including a base 1, a collimating cylinder 2, a first clamping arm group 3, and a second clamping arm group 4.

[0036] The structure of base 1 is as follows: Figure 4 As shown, it is L-shaped and includes a base plate 11 for placing a handheld laser rangefinder and a vertical plate 12 vertically disposed at one end of the base plate 11. A mounting hole is provided through the center of the vertical plate 12, and a collimating cylinder 2 is disposed at the mounting hole and located on the side away from the base plate 11. The outer wall of the collimating cylinder 2 is used to mate with the inner wall of the long pipe to be measured, and the inner hole is set to correspond to the laser emission port of the handheld laser rangefinder, and the central axis of the inner hole is coaxial with the optical axis of the laser beam path.

[0037] Because the inner diameters of the long pipes to be measured are different, the mounting holes are threaded holes to improve versatility. The collimating cylinder 2 includes a docking cylinder 21 and a centering cylinder 22 connected coaxially in sequence. The docking cylinder 21 is threaded to the mounting hole, and the outer wall of the centering cylinder 22 is used to fit with the inner wall of the long pipe to be measured. By selecting centering cylinders 22 with different outer diameters to adapt to long pipes with different inner diameters, the versatility of the device is improved.

[0038] A first guide groove 111, a first positioning pin hole 113, a second positioning pin hole 114 and a second guide groove 112 are sequentially provided on the base plate 11 along its length direction. The first guide groove 111 is close to the end of the connecting vertical plate 12, and the center lines of the four are all located in the mid-plane of the base plate 11 through the central axis of the mounting hole.

[0039] The first clamping arm group 3 and the second clamping arm group 4 are used to clamp the handheld laser rangefinder. They are located at the bottom of the base plate 11 and are symmetrically arranged with respect to the perpendicular bisector of the line connecting the center points of the first positioning pin hole 113 and the second positioning pin hole 114. They are the same size and structure. The first clamping arm group 3 includes a tensioning component and two sub-clamping arms 5 and two connecting arms 6 of the same size.

[0040] Each sub-clamping arm 5 includes a horizontal arm 51 and a vertical arm 52 vertically disposed on the horizontal arm 51. One end of the horizontal arm 51 is connected to the vertical arm 52, and the other end is provided with a second mating pin hole. A first mating pin hole is also provided on the horizontal arm 51 between the second mating pin hole and the vertical arm 52.

[0041] In this embodiment, to clamp the handheld laser rangefinder more quickly, the horizontal arm 51 includes a first arm 511 and a second arm 512. One end of the first arm 511 is connected to one end of the second arm 512, and a first mating pin hole is located at the connection position. A second mating pin hole is located at the other end of the first arm 511, and the other end of the second arm 512 is connected to the vertical arm 52. An angle A is formed between the first arm 511 and the second arm 512, and 120°≤A≤160°. In this embodiment, the angle A is 135°. To improve structural strength, the first arm 511 and the second arm 512 are integrally formed. The angle A of the horizontal arms 51 of the two sub-clamping arms 5 of the first clamping arm group 3 faces the side opposite to the vertical plate 12, while the angle A of the horizontal arms 51 of the two sub-clamping arms 5 of the second clamping arm group 4 faces the side furthest away from the vertical plate 12.

[0042] The vertical arm 52 is a cylindrical structure with a first threaded hole at its center along the axial direction. A clamping screw 10 is screwed into the first threaded hole. Figure 6 As shown, the clamping screw 10 presses the handheld laser rangefinder onto the base plate 11, while the vertical arm 52 clamps the handheld laser rangefinder.

[0043] The two sub-clamping arms 5 of the first clamping arm group 3 are arranged vertically, and the second docking pin holes of the two are set to correspond to the first positioning pin hole 113. The positioning pins 8 pass through the two second docking pin holes in sequence and are hinged to the first positioning pin hole 113. The first docking pin holes of the two are respectively hinged to one end of the two connecting arms 6. The other end of the two connecting arms 6 is hinged through the guide positioning pin 7, and the guide positioning pin 7 is slidably arranged in the first guide groove 111. In this way, the two sub-clamping arms 5 and the two connecting arms 6 together form a linkage clamping mechanism.

[0044] The tensioning assembly of the first clamping arm group 3 is mounted on the base plate 11 and connected to the corresponding guide positioning pin 7, used to pull the guide positioning pin 7 to slide along the first guide groove 111. In this embodiment, the tensioning assembly of the first clamping arm group 3 includes a first tensioning screw 9. The base plate 11 has a first through hole in the horizontal direction on the end face near the vertical plate 12. The first through hole is connected to the first guide groove 111. The first tensioning screw 9 passes through the first through hole and is threadedly connected to the corresponding guide positioning pin 7. The inner side of the tail of the first tensioning screw 9 abuts against the end face of the base plate 11. In order to achieve the threaded connection with the guide positioning pin 7, the guide positioning pin 7 has a second threaded hole in the radial direction. The first tensioning screw 9 is threadedly connected to the corresponding guide positioning pin 7 through the second threaded hole. The first tensioning screw 9 and the guide positioning pin 7 form a screw-nut kinematic pair. Rotating the first tensioning screw 9 will drive the guide positioning pin 7 to slide along the first guide groove 111, thereby driving the two sub-clamping arms 5 of the first clamping arm group 3 to move synchronously towards each other or away from each other.

[0045] The two sub-clamping arms 5 of the second clamping arm assembly 4 are arranged vertically, and their second mating pin holes are set to correspond to the second positioning pin holes 114. The two second mating pin holes are respectively hinged to the second positioning pin holes 114 by positioning pins 8. The first mating pin holes of the two are respectively hinged to one end of the two connecting arms 6. The other end of the two connecting arms 6 is hinged by guide positioning pins 7, and the guide positioning pins 7 are slidably arranged in the second guide groove 112. The tensioning component of the second clamping arm assembly 4 is arranged on the base plate 11 and connected to the corresponding guide positioning pins 7, which is used to pull the guide positioning pins 7 to slide along the second guide groove 112.

[0046] The tensioning assembly of the second clamping arm group 4 includes a second tensioning screw 91. The base plate 11 has a second through hole in the horizontal direction on the end face away from the vertical plate 12. The second through hole is connected to the second guide groove 112. After the second tensioning screw 91 passes through the second through hole, it is threadedly connected to the corresponding guide positioning pin 7. The inner side of the tail of the second tensioning screw 91 abuts against the end face of the base plate 11.

[0047] Similar to the first clamping arm assembly 3, in order to achieve a threaded connection with the guide positioning pin 7, the guide positioning pin 7 has a second threaded hole that runs radially through it. The second tensioning screw 91 is threadedly connected to the corresponding guide positioning pin 7 through the second threaded hole. The second tensioning screw 91 and the guide positioning pin 7 form a screw-nut motion pair. Rotating the second tensioning screw 91 will cause the guide positioning pin 7 to slide along the second guide groove 112, thereby causing the two sub-clamping arms 5 of the second clamping arm assembly 4 to move synchronously towards each other or away from each other.

[0048] In use, first rotate the first tension screw 9 and the second tension screw 91, causing the guide positioning pins 7 of the first clamping arm assembly 3 and the second clamping arm assembly 4 to move towards each other, thus opening the two sub-clamping arms 5 of the first clamping arm assembly 3 and the second clamping arm assembly 4. Then, place the handheld laser rangefinder on the base plate 11, and then rotate the first tension screw 9 and the second tension screw 91 in the opposite direction, causing the guide positioning pins 7 of the first clamping arm assembly 3 and the second clamping arm assembly 4 to move away from each other. At this time, the first clamping arm assembly 3 and the second clamping arm assembly 4... The two sub-clamping arms 5 move in opposite directions, thereby clamping the handheld laser rangefinder together through the four vertical arms 52. Then, the clamping screw 10 is adjusted to clamp the handheld laser rangefinder. Finally, a collimating cylinder 2 of appropriate specifications is selected according to the length of the pipe to be measured, and the centering cylinder 22 is inserted into the length of the pipe to be measured, so that the collimating cylinder 2 is coaxial with the length of the pipe to be measured. At this time, the optical axis of the laser beam emitted from the laser outlet of the handheld laser rangefinder is coaxial with the central axis of the collimating cylinder 2, thus avoiding the laser from deviating from the axis and irradiating the pipe wall.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A handheld laser rangefinder auxiliary fixing device for distance measurement in long pipelines, characterized in that: It includes a base (1), a collimating cylinder (2), a first clamping arm assembly (3), and a second clamping arm assembly (4); The base (1) is L-shaped and includes a base plate (11) for placing a handheld laser rangefinder and a vertical plate (12) vertically set at one end of the base plate (11); the center of the vertical plate (12) is provided with a mounting hole, the collimating cylinder (2) is set at the mounting hole and located on the side away from the base plate (11), the outer wall of the collimating cylinder (2) is used to cooperate with the inner wall of the long pipe to be measured, the inner hole is used to correspond to the laser emission port of the handheld laser rangefinder and the central axis of the inner hole is coaxial with the optical axis of the laser optical path; The base plate (11) is provided with a first guide groove (111), a first positioning pin hole (113), a second positioning pin hole (114) and a second guide groove (112) in sequence along its length direction. The first guide groove (111) is close to the end of the connecting vertical plate (12), and the center lines of the four are all located in the mid-plane of the base plate (11) through the central axis of the mounting hole. The first clamping arm group (3) and the second clamping arm group (4) have the same structural size and are both located at the bottom of the base plate (11). They are symmetrically arranged with respect to the perpendicular bisector of the line connecting the center points of the first positioning pin hole (113) and the second positioning pin hole (114). The first clamping arm group (3) includes a tensioning component and two sub-clamping arms (5) and two connecting arms (6) of the same structural size. The sub-clamping arm (5) includes a horizontal arm (51) and a vertical arm (52) vertically arranged on the horizontal arm (51). One end of the horizontal arm (51) is connected to the vertical arm (52), and the other end is provided with a second docking pin hole. A first docking pin hole is also provided on the horizontal arm (51) between the second docking pin hole and the vertical arm (52). The two sub-clamping arms (5) of the first clamping arm assembly (3) are arranged vertically, and the second docking pin holes of the two are set to correspond to the first positioning pin hole (113). The positioning pins (8) pass through the two second docking pin holes in sequence and are hinged to the first positioning pin hole (113). The first docking pin holes of the two are respectively hinged to one end of the two connecting arms (6). The other end of the two connecting arms (6) is hinged through the guide positioning pin (7), and the guide positioning pin (7) is slidably arranged in the first guide groove (111). The tensioning component of the first clamping arm assembly (3) is set on the base plate (11) and connected to the corresponding guide positioning pin (7) for pulling the guide positioning pin (7) to slide along the first guide groove (111). The second docking pin holes of the two sub-clamping arms (5) of the second clamping arm group (4) are respectively hinged to the second positioning pin hole (114) through positioning pins (8); the guide positioning pin (7) is slidably set in the second guide groove (112), and the tensioning component is used to pull the guide positioning pin (7) to slide along the second guide groove (112), so that the guide positioning pins (7) of the first clamping arm group (3) and the first clamping arm group (4) move in opposite directions, and then the handheld laser rangefinder is clamped together by the four vertical arms (52).

2. The auxiliary fixing device for a handheld laser rangefinder used for distance measurement in long pipelines according to claim 1, characterized in that: The tensioning assembly of the first clamping arm assembly (3) includes a first tensioning screw (9). The base plate (11) has a first through hole in the horizontal direction on the end face near the vertical plate (12). The first through hole is connected to the first guide groove (111). The first tensioning screw (9) passes through the first through hole and is threaded to the corresponding guide positioning pin (7). The inner side of the tail of the first tensioning screw (9) abuts against the end face of the base plate (11). The tensioning assembly of the second clamping arm assembly (4) includes a second tensioning screw (91). The base plate (11) has a second through hole in the horizontal direction on the end face away from the vertical plate (12). The second through hole is connected to the second guide groove (112). The second tensioning screw (91) passes through the second through hole and is threadedly connected to the corresponding guide positioning pin (7). The inner side of the tail of the second tensioning screw (91) abuts against the end face of the base plate (11).

3. The auxiliary fixing device for a handheld laser rangefinder used for distance measurement in long pipelines according to claim 2, characterized in that: The guide positioning pin (7) has a second threaded hole that extends radially through it. The first tensioning screw (9) and the second tensioning screw (91) are threadedly connected to the corresponding guide positioning pin (7) through the second threaded hole.

4. The auxiliary fixing device for a handheld laser rangefinder used for distance measurement in long pipelines according to claim 3, characterized in that: The horizontal arm (51) includes a first arm (511) and a second arm (512), one end of the first arm (511) is connected to one end of the second arm (512), and the first mating pin hole is provided at the connection position. The second connecting pin hole is located at the other end of the first arm (511), and the other end of the second arm (512) is connected to the vertical arm (52); there is an included angle A between the first arm (511) and the second arm (512), and 120°≤A≤160°; The included angle A of the horizontal arms (51) of the two sub-clamping arms (5) of the first clamping arm group (3) is directed toward the vertical plate (12); The included angle A of the horizontal arms (51) of the two sub-clamping arms (5) of the second clamping arm group (4) is directed toward the side far away from the vertical plate (12).

5. The auxiliary fixing device for a handheld laser rangefinder used for distance measurement in long pipelines according to claim 4, characterized in that: The vertical arm (52) is a cylindrical structure with a first threaded hole in its center along the axial direction, and a clamping screw (10) is screwed into the first threaded hole.

6. The auxiliary fixing device for a handheld laser rangefinder used for distance measurement in long pipelines according to claim 5, characterized in that: The mounting hole is a threaded hole. The collimating cylinder (2) includes a docking cylinder (21) and a centering cylinder (22) connected coaxially in sequence. The docking cylinder (21) is threadedly engaged with the mounting hole. The outer wall of the centering cylinder (22) is used to engage with the inner wall of the long pipe to be measured.

7. The auxiliary fixing device for a handheld laser rangefinder used for distance measurement in long pipelines according to claim 4, characterized in that: The first arm (511) and the second arm (512) are integrally formed.

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