A four-way caliper

Abstract

The application relates to a four-way caliper gauge, which comprises a four-way caliper gauge body, two calibration devices, two calibration devices are respectively arranged on two sides of the four-way caliper gauge body, the calibration device comprises a calibration frame and two groups of clamping assemblies, the two groups of clamping assemblies are distributed along the length direction of a to-be-measured object, the clamping assembly comprises a plurality of maintaining pieces, the plurality of maintaining pieces are uniformly distributed in the circumferential direction of a measurement reference axis, the maintaining piece comprises a maintaining cylinder, a maintaining plate, a maintaining wheel, a maintaining spring and a maintaining block, the maintaining cylinder is arranged on the calibration frame, the maintaining plate is arranged on a piston rod of the maintaining cylinder, the maintaining block is slidably connected to the maintaining plate in the length direction of the piston rod of the maintaining cylinder, the maintaining wheel is rotatably connected to the maintaining block, the maintaining wheel is rollably connected to the surface of the to-be-measured object, and the maintaining spring is used for maintaining the abutting of the maintaining wheel to the surface of the to-be-measured object. The application has the effect that the measured object is always arranged at the measurement reference axis.

Description

Technical Field

[0001] This application relates to the field of diameter gauges, and more particularly to a four-directional diameter gauge. Background Technology

[0002] A diameter gauge is a non-contact measuring device, mainly used for dimensional inspection in industrial fields such as wires, cables, pipes, and optical fibers. A four-way diameter gauge is a type of diameter gauge that has four sets of measuring units that are evenly distributed around the object being measured in 360°. It can collect the diameter values ​​of the same cross section of the object in four directions.

[0003] Currently, Chinese utility model patent CN217276033U discloses a bidirectional diameter measuring instrument with adjustable roller positions. The instrument includes a housing with a through groove for measuring the diameter of the object being measured. Rollers for supporting the object are located on both sides of the housing. The axes of all rollers are located on the same horizontal plane and are parallel to each other. Each roller is connected to a bracket, and both ends of the rollers are rotatably connected to the ends of the bracket. The bracket is connected to the housing via an adjustment mechanism for adjusting the position of the rollers horizontally or vertically. This application facilitates the adjustment of the height of the object being measured.

[0004] The measurement reference axis of the four-axis diameter gauge is the straight line where the optical axes of the four measurement units intersect. Some of the surfaces of the measured objects are uneven and have protrusions. When the protrusions of the measured objects come into contact with the rollers, the measured objects will be lifted up, and the position of the measured objects relative to the rollers will change. At this time, the measured objects will deviate from the measurement reference axis, resulting in deviations in the measurement data. Summary of the Invention

[0005] In order to ensure that the object being measured is always at the measurement reference axis, this application provides a four-way diameter measuring instrument.

[0006] This application provides a four-directional diameter measuring instrument, which adopts the following technical solution: A four-axis diameter measuring instrument includes a four-axis diameter measuring instrument body and two calibration devices located on opposite sides of the four-axis diameter measuring instrument body. Each calibration device includes a calibration frame and two sets of clamping assemblies. The two sets of clamping assemblies are distributed along the length direction of the object to be measured. Each clamping assembly includes several holding members evenly distributed circumferentially along a measurement reference axis. Each holding member includes a holding cylinder, a holding plate, a holding wheel, a holding spring, and a holding block. The length direction of the holding cylinder is perpendicular to the measurement reference axis. The holding cylinder is mounted on the calibration frame. The holding plate is mounted on the piston rod of the holding cylinder. The holding block is slidably connected to the holding plate along the extension / retraction direction of the piston rod of the holding cylinder. The holding wheel is rotatably connected to the holding block and rolls against the surface of the object to be measured. The holding spring is used to keep the holding wheel abutting against the surface of the object to be measured.

[0007] By adopting the above technical solution, calibration devices are set on both sides. Each calibration device includes two sets of clamping components distributed along the length of the object to be measured. In each set of clamping components, multiple holding members are evenly distributed circumferentially along the measurement reference axis. The holding members achieve flexible floating through holding cylinders and holding springs. The holding wheel always abuts against the surface of the object to be measured. The holding members evenly distributed in multiple directions form a flexible centering constraint. The elastic buffer of the holding springs can offset the lateral force generated by the surface protrusion and deformation of the object to be measured, thus preventing the workpiece from deviating from the measurement reference axis. At the same time, the rigid support of the holding cylinders can ensure the basic guiding accuracy and improve the stability of the measurement data.

[0008] Optionally, the diameters at both ends of the maintaining wheel are larger than the diameter at the middle of the maintaining wheel, and the sidewalls of the maintaining wheel are in contact with the surface of the object to be measured.

[0009] By adopting the above technical solution, the structure of the wheel, which is narrow in the middle and wide at both ends, is adapted to the outer circle contour of the object to be measured, thereby increasing the contact area with the workpiece, reducing the pressure of single-point contact, and avoiding slippage caused by local protrusions of the workpiece. At the same time, the close contact can guide the workpiece to move along the measurement reference axis, further reducing the risk of deviation.

[0010] Optionally, several auxiliary components are provided between the two sets of clamping assemblies to improve the stability of the object to be measured. The auxiliary components correspond to several holding components. The auxiliary components include a mounting frame and two auxiliary rollers. The mounting frame is set on the holding plate, and the two auxiliary rollers are rotatably connected to the mounting frame. The rotation axis of the auxiliary rollers makes an angle of 45° with the measurement reference axis. The distance between the two auxiliary rollers gradually increases along the movement direction of the object to be measured. The auxiliary rollers of the several auxiliary components are distributed in a zigzag pattern, and the sidewalls of the auxiliary rollers abut against the surface of the object to be measured.

[0011] By adopting the above technical solution, the auxiliary roller with a 45° included angle forms a "gradual guiding constraint" to perform secondary centering of the object to be measured. Especially for the middle section of long workpieces, it can correct the slight bending caused by clamping at both ends. The auxiliary roller with a zigzag distribution can disperse the stress caused by the deformation of the workpiece, avoid the deviation caused by excessive local force, and improve the overall guiding stability.

[0012] Optionally, the auxiliary roller includes a roller body and a rubber layer. The roller body is rotatably connected to the mounting frame. The diameters at both ends of the roller body are larger than the diameter at the middle of the roller body. The rubber layer wraps around the sidewall of the roller body and is rolled onto the surface of the object to be measured.

[0013] By adopting the above technical solution, the roller structure is adapted to the workpiece contour, and the rubber layer further buffers the impact of the workpiece protrusion through elastic deformation, reducing the damage to the workpiece surface caused by rigid contact; at the same time, the rubber layer increases the friction with the workpiece, preventing the workpiece from slipping during high-speed movement and ensuring that the workpiece stably passes through the measurement reference axis.

[0014] Optionally, the mounting frame is provided with a cleaning component for cleaning impurities on the surface of the rubber layer. The cleaning component includes a scraper and a cleaning box. The scraper is slidably connected to the mounting frame along the direction of the measurement reference axis. The cleaning box is disposed on the scraper. An inlet groove is opened on the scraper. The interior of the cleaning box communicates with the inlet groove.

[0015] By adopting the above technical solution, the problem of dust, metal shavings and other impurities easily adhering to the rubber layer due to long-term contact with the workpiece is solved, avoiding uneven contact force or scratches on the workpiece surface caused by impurities; the collection function of the cleaning box reduces the risk of impurities falling into the measurement area and reduces the impact of external interference on measurement accuracy.

[0016] Optionally, the cleaning box includes a box body, a cover, and a magnet. The box body is disposed on the scraper, the magnet is disposed at the opening of the box body, the cover is made of metal, and the cover is provided with a flange. When the magnet causes the cover to seal the opening of the box body, the flange is located inside the box body.

[0017] By adopting the above technical solution, the magnetic attraction between the magnet and the metal cover achieves rapid sealing, preventing impurities from leaking out of the cleaning box; the flange design enhances the sealing performance, while also making it easier to open the cover to empty impurities, thus improving maintenance convenience.

[0018] Optionally, the mounting frame is provided with a drive assembly for intermittently driving the scraper to abut against the surface of the auxiliary roller. The drive assembly includes a universal joint, a spacer, and a reciprocating component. One end of the universal joint is disposed on one of the roller bodies, and the other end of the universal joint is parallel to the measuring reference axis and rotatably connected to the mounting frame. The spacer includes a drive wheel and a spacer wheel. The drive wheel is disposed on the universal joint and coaxially with one end of the universal joint rotatably connected to the mounting frame. The drive wheel is provided with a toggle block and a limiting plate. The toggle block is eccentrically disposed on the drive wheel, and the limiting plate is coaxially disposed with the drive wheel. The spacer wheel is rotatably connected to the mounting frame. The spacer wheel has several limiting grooves for engaging with the limiting plate. The spacer wheel has several toggle grooves for accommodating the toggle block. The reciprocating component is disposed on the spacer wheel and is used to drive the scraper to slide.

[0019] By adopting the above technical solution, the workpiece movement drives the auxiliary roller to rotate. Through the linkage of the universal joint, drive wheel, and spacer wheel, the rotational motion of the roller is converted into the reciprocating sliding of the scraper, realizing automatic cleaning with the movement of the workpiece without the need for an additional power source. Intermittent cleaning can avoid wear caused by the scraper's long-term contact with the auxiliary roller, extend the service life of the components, and at the same time ensure the cleanliness of the rubber layer surface.

[0020] Optionally, the reciprocating component includes a reciprocating wheel and a guide post. The reciprocating wheel is disposed on the spacer wheel, and a guide groove is formed on the reciprocating wheel. The guide groove includes two arc-shaped grooves and two transition grooves. The two arc-shaped grooves and the two transition grooves are staggered. The two arc-shaped grooves are distributed along the direction of the measurement reference axis. The arc-shaped grooves are connected to the transition grooves, and the arc-shaped grooves and the transition grooves form a circumferential path. The guide post is disposed on the scraper, and the guide post is located in the guide groove.

[0021] By adopting the above technical solution, the circumferential path formed by the arc groove and the transition groove guides the guide column to perform reciprocating and pausing movements, enabling the scraper to achieve a cyclical action of contact, cleaning, disengagement, and resetting, which not only ensures the cleaning effect but also reduces continuous friction with the auxiliary roller; the structure is simple and reliable, and is suitable for the dynamic cleaning needs of high-speed production lines.

[0022] Optionally, the calibration frame is provided with a cover to reduce external light interference. The cover includes a first half cover and a second half cover. The first half cover and the second half cover are slidably connected to the calibration frame along the direction of the measurement reference axis. The first half cover and the second half cover can form a complete cylindrical structure. The first half cover and the second half cover are both bolted to the body of the four-way diameter measuring instrument.

[0023] By adopting the above technical solution, the cylindrical cover can block external light, such as workshop lights and sunlight, from entering the measurement area, avoid light interference with the optical sensor of the four-way diameter gauge, reduce light clutter leading to edge detection errors, and the sliding structure facilitates the loading and unloading of workpieces and maintenance of equipment, taking into account both protection and operability.

[0024] Optionally, the calibration frame is further provided with an auxiliary cover to reduce dust adhesion to the analyte. The auxiliary cover is located between two sets of clamping components. The auxiliary cover includes a fixed cover, a first sliding cover, and a second sliding cover. The fixed cover is cylindrical, and its axis is parallel to the direction of the measurement reference axis. One end of the fixed cover is disposed on the calibration frame. The first sliding cover is fitted onto the fixed cover and is slidably connected to the fixed cover along the direction of the measurement reference axis. The second sliding cover is fitted onto the first sliding cover and is slidably connected to the first sliding cover along the direction of the measurement reference axis. The end of the second sliding cover away from the fixed cover is bolted to the calibration frame.

[0025] By adopting the above technical solution, the telescopic structure makes it easy for staff to operate the cleaning parts. When a closed space is formed, it can reduce the adhesion of dust, water mist and other impurities to the surface of the workpiece. In conjunction with the cover, the measurement environment is optimized in terms of both light protection and impurity protection, further improving the stability of measurement accuracy.

[0026] In summary, this application includes at least one of the following beneficial technical effects: A multi-dimensional flexible constraint is formed by multiple sets of support members distributed circumferentially along the measurement reference axis, support wheels that are wide at both ends and narrow in the middle, and auxiliary rollers with a 45° included angle. The support spring and rubber layer provide cushioning, which can counteract the lateral force generated by the protrusion and deformation of the measured object surface, reduce the occurrence of the measured object deviating from the measurement reference axis, and ensure the accuracy of the measurement data. The cleaning components and drive assembly can automatically remove impurities from the surface of the auxiliary roller, preventing impurities from affecting contact stability. The cover and auxiliary cover can reduce external light and dust interference, adapting to industrial environments such as dust and strong light. Flexible constraints ensure stable guidance during measurement, while sliding covers, retractable auxiliary covers, and magnetic cleaning box covers reduce the difficulty of daily cleaning and component replacement. The drive components utilize the movement of the measured object to achieve automatic cleaning, reducing additional power consumption and manual intervention, and improving the operating efficiency and maintenance convenience of the equipment. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a four-way diameter gauge.

[0028] Figure 2 This is a schematic diagram of the retaining element.

[0029] Figure 3 yes Figure 1 A schematic diagram of the auxiliary components.

[0030] Figure 4 yes Figure 3 Exploded view of the auxiliary roller.

[0031] Figure 5 yes Figure 4 A schematic diagram of the structure of the driving component.

[0032] Figure 6 yes Figure 5 Schematic diagram of the intermediate spacer and reciprocating component.

[0033] Figure 7 yes Figure 1 A schematic diagram of the structure of the central cover and the fixed cover.

[0034] Reference numerals: 1. Four-way diameter gauge body; 2. Calibration frame; 3. Clamping assembly; 4. Holding cylinder; 41. Holding plate; 42. Holding wheel; 43. Holding spring; 44. Holding block; 5. Auxiliary component; 51. Mounting frame; 52. Auxiliary roller; 521. Roller body; 522. Rubber layer; 6. Cleaning component; 61. Scraper; 611. Inlet groove; 62. Cleaning box; 621. Box body; 622. Cover; 623. Magnet; 624. Flange; 7. Drive assembly; 7 1. Universal joint; 72. Spacer; 721. Drive wheel; 722. Spacer wheel; 723. Actuating block; 724. Limiting plate; 725. Actuating groove; 726. Limiting groove; 727. Clearance groove; 73. Reciprocating component; 731. Reciprocating wheel; 732. Guide post; 733. Arc groove; 734. Transition groove; 8. Cover; 81. First half cover; 82. Second half cover; 9. Auxiliary cover; 91. Fixed cover; 92. First sliding cover; 93. Second sliding cover. Detailed Implementation

[0035] The following is in conjunction with the appendix Figure 1 - Appendix Figure 7 This application will be described in further detail.

[0036] This application discloses a four-directional diameter measuring instrument. (Refer to...) Figure 1 and Figure 2 A four-directional diameter measuring instrument includes a four-directional diameter measuring instrument body 1 and two calibration devices. The two calibration devices are located on both sides of the four-directional diameter measuring instrument body 1 along the width direction and are distributed along the measurement reference axis. The calibration device includes a calibration frame 2 and two sets of clamping components 3. The calibration frame 2 is fixedly installed on the four-directional diameter measuring instrument body 1, and the two sets of clamping components 3 are distributed along the measurement reference axis.

[0037] Reference Figure 1 and Figure 2 The clamping assembly 3 includes three holding members, which are evenly distributed circumferentially along the measurement reference axis. Each holding member includes a holding cylinder 4, a holding plate 41, a holding wheel 42, a holding spring 43, and a holding block 44. The length direction of the holding cylinder 4 is perpendicular to the measurement reference axis. The cylinder body of the holding cylinder 4 is fixedly mounted on the calibration frame 2. The piston rod of the holding cylinder 4 passes through the calibration frame 2. The holding plate 41 is fixedly mounted on the piston rod of the holding cylinder 4. The holding block 44 is located on the side of the holding plate 41 facing the measurement reference axis, and extends along the length of the piston rod of the holding cylinder 4. The directional sliding connection is on the holding plate 41. The length direction of the holding spring 43 is parallel to the sliding direction of the holding block 44. The holding spring 43 is located between the holding block 44 and the holding plate 41. One end of the holding spring 43 is fixedly set on the holding plate 41, and the other end of the holding spring 43 is fixedly set on the holding block 44. The diameter of both ends of the holding wheel 42 is greater than the diameter of the middle part of the gear. The axis of the holding wheel 42 is perpendicular to the measuring reference axis and tangent to the surface of the object to be measured. The holding wheel 42 is rotatably connected to the holding block 44, and the side wall of the holding wheel 42 is in contact with the surface of the object to be measured.

[0038] Reference Figure 3 and Figure 4 Three sets of auxiliary components 5 are provided between the two sets of clamping components 3. The three sets of auxiliary components 5 correspond one-to-one with the three holding components. The auxiliary component 5 includes a mounting frame 51 and two auxiliary rollers 52. Both ends of the mounting frame 51 are set on the holding plate 41. A total of six auxiliary rollers 52 in the three sets of auxiliary components 5 are evenly distributed circumferentially along the measurement reference axis. The angle between the length direction of the auxiliary roller 52 and the measurement reference axis is 45°. The distance between the two auxiliary rollers 52 in the same set of auxiliary components 5 gradually increases along the conveying direction of the object to be tested. The auxiliary roller 52 includes a roller body 521 and a rubber layer 522. The roller body 521 is rotatably connected to the mounting frame 51. The diameters at both ends of the roller body 521 are relative to the diameter at the middle of the roller body 521. The rubber layer 522 wraps around the side wall of the roller body 521 and the side wall of the rubber layer 522 is in contact with the surface of the object to be tested.

[0039] Reference Figure 3 and Figure 4A cleaning component 6 is provided on the mounting frame 51. The cleaning component 6 includes a scraper 61 and a cleaning box 62. The scraper 61 is slidably connected to the mounting frame 51 along the direction of the measuring reference axis. The scraper 61 abuts against the rubber layer 522 of the two rollers 521 of the same auxiliary component 5. The cleaning box 62 is fixedly mounted on the scraper 61. The cleaning box 62 includes a box body 621, a cover body 622, and a magnet 623. The box body 621 is fixedly mounted on the scraper 61. An inlet groove 611 is provided on the top, which communicates with the inside of the box body 621. A magnet 623 is fixedly installed at the opening of the box body 621. The cover 622 is made of metal and is used to cover the opening of the box body 621. A flange 624 is fixedly provided on the cover 622. When the cover 622 covers the opening of the box body 621 through the magnet 623, the flange 624 is located inside the box body 621 and abuts against the inner side wall of the box body 621.

[0040] Reference Figure 5 and Figure 6 The mounting frame 51 is equipped with a drive assembly 7 that drives the scraper to intermittently abut against the rubber layer 522. The drive assembly 7 includes a universal joint 71, a spacer 72, and a reciprocating component 73. One end of the universal joint 71 is fixedly mounted on one end of a corresponding roller 521, and the other end of the universal joint 71 is parallel to the measuring reference axis and rotatably connected to the mounting frame 51. The spacer 72 includes a drive wheel 721 and a spacer wheel 722. The drive wheel 721 is rotatably connected to one end of the mounting frame 51 and coaxially mounted with the universal joint 71. The drive wheel 721 is fixedly mounted on the universal joint 71. The drive wheel 721 is equipped with a toggle block 723 and a limit plate 724. The toggle block 723 is eccentrically mounted on the drive wheel 721, and the limit plate 724 is coaxially mounted with the drive wheel 721. The disc 724 is fixedly mounted on the drive wheel 721. The axis of the spacer wheel 722 is parallel to the axis of the drive wheel 721. The spacer wheel 722 is rotatably connected to the mounting bracket 51. The spacer wheel 722 has four actuating grooves 725, which are evenly distributed circumferentially along the axis of the spacer wheel 722. The actuating grooves 725 extend radially along the spacer wheel 722 and are used to accommodate the actuating block 723. The spacer wheel 722 also has four limiting grooves 726, which are staggered with the four actuating grooves 725. The limiting grooves 726 are used to abut against the limiting disc 724. The limiting disc 724 has a clearance groove 727 on its side wall facing the actuating block 723. The clearance groove 727 is used to avoid the spacer wheel 722 when it rotates.

[0041] Reference Figure 5 and Figure 6The reciprocating component 73 is disposed on the spacer wheel 722. The reciprocating component 73 includes a reciprocating wheel 731 and a guide post 732. The reciprocating wheel 731 is coaxially disposed with the spacer wheel 722. The reciprocating wheel 731 is fixedly disposed on the end face of the spacer wheel 722. A guide groove is provided on the reciprocating wheel 731. The guide groove includes two arc-shaped grooves 733 and two transition grooves 734. The two arc-shaped grooves 733 and the two transition grooves 734 are staggered along the circumference of the reciprocating wheel 731. The two arc-shaped grooves 733 are distributed along the axial direction of the reciprocating wheel 731. The two ends of the transition grooves 734 are connected to the two arc-shaped grooves 733. The two arc-shaped grooves 733 and the two transition grooves 734 form a circumferential path. The guide post 732 is fixedly disposed on the scraper 61 and is located in the guide groove.

[0042] Reference Figure 1 and Figure 7 The calibration frame 2 is equipped with a cover 8 to reduce interference from external light. The cover 8 includes a first half cover 81 and a second half cover 82. The first half cover 81 and the second half cover 82 are slidably connected to the transfer frame along the direction of the measurement reference axis. The first half cover 81 and the second half cover 82 can form a complete cylindrical structure. The first half cover 81 and the second half cover 82 are both connected to the four-way diameter measuring instrument body 1 by bolts.

[0043] Reference Figure 1 and Figure 7 The calibration frame 2 is also equipped with an auxiliary cover 9 to reduce dust adhesion. The auxiliary cover 9 is located between two clamping components 3. The auxiliary cover 9 includes a fixed cover 91, a first sliding cover 92 and a second sliding cover 93. The fixed cover 91 is cylindrical and its axis is parallel to the measurement reference axis. One end of the fixed cover 91 is fixedly mounted on the calibration frame 2. The first sliding cover 92 is fitted onto the fixed cover 91 and is slidably connected to the fixed cover 91 along the axis of the fixed axis. The second sliding cover 93 is fitted onto the first sliding cover 92 and is fitted onto the first sliding cover 92 along the axis of the first sliding cover 92. The end of the second sliding cover 93 away from the fixed cover 91 is connected to the calibration frame 2 by bolts.

[0044] The implementation principle of a four-directional diameter measuring instrument according to an embodiment of this application is as follows: multiple sets of maintaining components are evenly distributed circumferentially along the measurement reference axis. The maintaining cylinder 4 provides basic support. The maintaining spring 43 uses elastic force to keep the maintaining wheel 42 always in contact with the surface of the object to be measured, forming a multi-directional flexible constraint. When the object to be measured has surface protrusions or deformation, the buffering effect of the maintaining spring 43 can offset the local lateral force and prevent the workpiece from being pushed off course. The structure of the maintaining wheel 42, which is wide at both ends and narrow in the middle, is adapted to the outer circle of the workpiece, increasing the contact area to stabilize the guide. The auxiliary component 5 between the two sets of clamping components 3 forms a secondary center through the auxiliary roller 52 with a 45° included angle, correcting the bending of the middle section of the long workpiece and ensuring that the workpiece moves along the measurement reference axis.

[0045] The rubber layer 522 of the auxiliary roller 52 enhances the friction with the workpiece. The drive assembly 7 drives the scraper 61 to clean impurities on the surface of the rubber layer 522 through the movement of the object being measured. When the workpiece moves, the rotation of the auxiliary roller 52 triggers the universal joint 71, the spacer wheel 722 and other transmission structures, causing the scraper 61 to slide along the measurement reference axis. The limiting groove 726 of the reciprocating part 73 controls the scraper 61 to contact and clean and then disengage and reset, avoiding uneven contact force caused by impurity accumulation and ensuring guiding stability.

[0046] The cylindrical cover 8, composed of the first half-cover 81 and the second half-cover 82, prevents external light from interfering with the optical measurement unit. The fixed cover 91 and sliding cover of the auxiliary cover 9 can be adapted to workpieces of different lengths, forming a local clean space, reducing dust and oil pollution on the workpiece surface and measuring components, and reducing measurement errors caused by environmental factors.

[0047] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A four-directional diameter gauge, comprising a four-directional diameter gauge body (1), characterized in that: Two calibration devices are located on both sides of the four-axis diameter measuring instrument body (1). Each calibration device includes a calibration frame (2) and two sets of clamping assemblies (3). The two sets of clamping assemblies (3) are distributed along the length direction of the object to be measured. Each clamping assembly (3) includes several holding members, which are evenly distributed circumferentially along the measurement reference axis. Each holding member includes a holding cylinder (4), a holding plate (41), a holding wheel (42), a holding spring (43), and a holding block (44). The length direction of the holding cylinder (4) is perpendicular to the measuring reference axis. The reference axis is measured. The holding cylinder (4) is set on the calibration frame (2). The holding plate (41) is set on the piston rod of the holding cylinder (4). The holding block (44) is slidably connected to the holding plate (41) along the extension and retraction direction of the piston rod of the holding cylinder (4). The holding wheel (42) is rotatably connected to the holding block (44). The holding wheel (42) is rolled on the surface of the object to be measured. The holding spring (43) is used to keep the holding wheel (42) against the surface of the object to be measured.

2. A four-directional diameter measuring instrument according to claim 1, characterized in that: The diameters at both ends of the maintaining wheel (42) are larger than the diameter in the middle of the maintaining wheel (42), and the sidewalls of the maintaining wheel (42) are in contact with the surface of the object to be measured.

3. A four-directional diameter measuring instrument according to claim 1, characterized in that: Between the two sets of clamping components (3), there are several auxiliary components (5) to improve the stability of the object to be measured. The auxiliary components (5) correspond to several maintaining components. The auxiliary components (5) include a mounting frame (51) and two auxiliary rollers (52). The mounting frame (51) is set on the maintaining plate (41). The two auxiliary rollers (52) are rotatably connected to the mounting frame (51). The rotation axis of the auxiliary rollers (52) makes an angle of 45° with the measurement reference axis. The distance between the two auxiliary rollers (52) gradually increases along the movement direction of the object to be measured. The auxiliary rollers (52) of the several auxiliary components (5) are distributed in a zigzag pattern. The sidewall of the auxiliary rollers (52) abuts against the surface of the object to be measured.

4. A four-directional diameter measuring instrument according to claim 3, characterized in that: The auxiliary roller (52) includes a roller body (521) and a rubber layer (522). The roller body (521) is rotatably connected to the mounting frame (51). The diameters at both ends of the roller body (521) are larger than the diameter in the middle of the roller body (521). The rubber layer (522) wraps around the side wall of the roller body (521) and is rolled onto the surface of the object to be measured.

5. A four-directional diameter measuring instrument according to claim 4, characterized in that: The mounting bracket (51) is provided with a cleaning component (6) for cleaning impurities on the surface of the rubber layer (522). The cleaning component (6) includes a scraper (61) and a cleaning box (62). The scraper (61) is slidably connected to the mounting bracket (51) along the direction of the measurement reference axis. The cleaning box (62) is disposed on the scraper (61). An entry groove (611) is provided on the scraper (61). The interior of the cleaning box (62) communicates with the entry groove (611).

6. A four-directional diameter measuring instrument according to claim 5, characterized in that: The cleaning box (62) includes a box body (621), a cover (622), and a magnet (623). The box body (621) is disposed on the scraper (61), and the magnet (623) is disposed at the opening of the box body (621). The cover (622) is made of metal and has a flange (624). When the magnet (623) causes the cover (622) to seal the opening of the box body (621), the flange (624) is located inside the box body (621).

7. A four-directional diameter measuring instrument according to claim 5, characterized in that: The mounting frame (51) is provided with a drive assembly (7) for driving the scraper to intermittently abut against the surface of the auxiliary roller (52). The drive assembly (7) includes a universal joint (71), a spacer (72), and a reciprocating component (73). One end of the universal joint (71) is disposed on one of the roller bodies (521), and the other end of the universal joint (71) is parallel to and rotatably connected to the mounting frame (51) with respect to the measurement reference axis. The spacer (72) includes a drive wheel (721) and a spacer wheel (722). The drive wheel (721) is disposed on one end of the universal joint (71) rotatably connected to the mounting frame (51) and is coaxially disposed thereon. The drive wheel (721) is disposed on the universal joint (71). The device is equipped with an actuating block (723) and a limiting plate (724). The actuating block (723) is eccentrically mounted on the drive wheel (721). The limiting plate (724) is coaxially mounted with the drive wheel (721). The spacer wheel (722) is rotatably connected to the mounting bracket (51). The spacer wheel (722) has several limiting grooves (726) for engaging with the limiting plate (724). The spacer wheel (722) has several actuating grooves (725) for accommodating the actuating block (723). The reciprocating component (73) is mounted on the spacer wheel (722) and is used to drive the scraper (61) to slide.

8. A four-directional diameter measuring instrument according to claim 7, characterized in that: The reciprocating component (73) includes a reciprocating wheel (731) and a guide post (732). The reciprocating wheel (731) is disposed on the spacer wheel (722). A guide groove is provided on the reciprocating wheel (731). The guide groove includes two arc-shaped grooves (733) and two transition grooves (734). The two arc-shaped grooves (733) and the two transition grooves (734) are staggered. The two arc-shaped grooves (733) are distributed along the direction of the measurement reference axis. The arc-shaped grooves (733) and the transition grooves (734) are connected. The arc-shaped grooves (733) and the transition grooves (734) form a circumferential path. The guide post (732) is disposed on the scraper (61). The guide post (732) is located in the guide groove.

9. A four-directional diameter measuring instrument according to claim 1, characterized in that: The calibration frame (2) is provided with a cover (8) for reducing external light interference. The cover (8) includes a first half cover (81) and a second half cover (82). The first half cover (81) and the second half cover (82) are slidably connected to the calibration frame (2) along the direction of the measurement reference axis. The first half cover (81) and the second half cover (82) can form a complete cylindrical structure. The first half cover (81) and the second half cover (82) are both connected to the four-way diameter measuring instrument body (1) by bolts.

10. A four-directional diameter measuring instrument according to claim 1, characterized in that: The calibration frame (2) is also provided with an auxiliary cover (9) to reduce dust adhesion to the object to be measured. The auxiliary cover (9) is located between two sets of clamping components (3). The auxiliary cover (9) includes a fixed cover (91), a first sliding cover (92) and a second sliding cover (93). The fixed cover (91) is cylindrical. The axis of the fixed cover (91) is parallel to the direction of the measurement reference axis. One end of the fixed cover (91) is set on the calibration frame (2). The first sliding cover (92) is sleeved on the fixed cover (91). The first sliding cover (92) slides along the direction of the measurement reference axis and is connected to the fixed cover (91). The second sliding cover (93) is sleeved on the first sliding cover (92). The second sliding cover (93) slides along the direction of the measurement reference axis and is connected to the first sliding cover (92). The end of the second sliding cover (93) away from the fixed cover (91) is connected to the calibration frame (2) by bolts.

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