In-situ measuring fixture

Abstract

This utility model belongs to the field of precision measurement technology, specifically relating to an in-situ measurement fixture, including a frame, an X-axis measuring screw, a Y-axis measuring screw, a first limiting guide rail, and a second limiting guide rail. The X-axis measuring screw has an X-axis scale line, and the Y-axis measuring screw has a Y-axis scale line. Measuring nuts are threaded onto both the X-axis and Y-axis measuring screws, and each measuring nut has an annular scale line. A sleeve is rotatably connected to each measuring nut. Two measuring nuts are provided on both the X-axis and Y-axis measuring screws. A first clamping jaw is provided on the sleeve on the X-axis measuring screw, and a second clamping jaw is provided on the sleeve on the Y-axis measuring screw. The X-axis scale line and the annular scale line cooperate to mark the position of the measuring nut on the X-axis measuring screw, and the Y-axis scale line and the annular scale line cooperate to mark the position of the measuring nut on the Y-axis measuring screw, improving the adjustment accuracy of the measuring nuts and enhancing the in-situ positioning and measurement accuracy of the sample.

Description

Technical Field

[0001] This utility model belongs to the field of precision measurement technology, specifically relating to an in-situ measurement fixture. Background Technology

[0002] Precision testing equipment is widely used in scientific research and production in the fields of optics, electronics, and communications. For example, it is used for laser damage observation experiments of mechanical components and quality inspection of precision workpieces. Using testing devices such as coordinate measuring machines, optical microscopes, X-ray inspection equipment, ultrasonic testing equipment, and atomic force microscopes, the equipment is used to detect parameters such as the size, shape, surface roughness, and mechanical properties of test samples or workpieces, ensuring the reliability of experiments and the quality of industrial products.

[0003] Testing equipment typically includes a stage with positioning fixtures. During testing, the sample to be tested is placed on the stage, and the positioning fixtures hold and position the sample in the same location. This ensures that the workpiece maintains the same horizontal position on the stage during multiple measurements, reducing measurement errors in the same batch of workpieces in industrial production and improving product quality. It also ensures that the same sample is maintained in the same position during repeated testing, achieving in-situ measurement and improving experimental reliability. However, these positioning fixtures generally only position the sample at the same location on the stage. In experiments and production, some workpieces require multiple horizontal movements during measurement to detect multiple features. Existing positioning fixtures cannot meet these requirements. Instead, the sample's position must be manually marked on the stage, which is not only cumbersome and inefficient but also fails to guarantee in-situ measurement, affecting the measurement accuracy of the same feature on the sample. This can easily lead to significant quality deviations in the same batch of products in industrial production and incorrect results during the experiment. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide an in-situ measurement fixture to improve the in-situ positioning accuracy and in-situ measurement accuracy of the sample to be tested.

[0005] The technical solution adopted by this utility model to solve the technical problem is: an in-situ measuring fixture, including a frame, on which are provided an X-direction measuring screw, a Y-direction measuring screw, a first limiting guide rail parallel to the X-direction measuring screw, and a second limiting guide rail parallel to the Y-direction measuring screw, wherein the X-direction measuring screw and the Y-direction measuring screw are arranged perpendicular to each other;

[0006] The X-axis measuring screw has an X-axis scale surface extending along its axial direction on its side wall, and the X-axis scale surface is provided with X-axis scale lines parallel to the axis of the X-axis measuring screw; the Y-axis measuring screw has a Y-axis scale surface extending along its axial direction on its side wall, and the Y-axis scale surface is provided with Y-axis scale lines parallel to the axis of the Y-axis measuring screw.

[0007] Both the X-axis measuring screw and the Y-axis measuring screw are fitted with measuring nuts that are threadedly connected to them. The outer contour of the cross-section of the measuring nut is circular and its outer side wall is provided with an annular scale line coaxial with it. A sleeve is rotatably connected to the measuring nut on the same axis. The measuring nut is provided with an axial positioning part, which is used to axially position the sleeve on the measuring nut.

[0008] Both the X-axis measuring screw and the Y-axis measuring screw are provided with two measuring nuts; the sleeves of the two measuring nuts on the X-axis measuring screw are respectively provided with first clamping claws that are axially slidably connected to the first limiting guide rail, and the clamping surfaces of the two first clamping claws are close to each other; the sleeves of the two measuring nuts on the Y-axis measuring screw are respectively provided with second clamping claws that are axially slidably connected to the second limiting guide rail, and the clamping surfaces of the two second clamping claws are close to each other.

[0009] Furthermore, the frame includes a rectangular frame arranged in a horizontal direction, and each of the four corners of the bottom surface of the rectangular frame is provided with a column;

[0010] Both ends of the X-axis measuring screw and both ends of the Y-axis measuring screw are mounted on the column, and both the X-axis measuring screw and the Y-axis measuring screw are arranged at intervals from the bottom surface of the rectangular frame.

[0011] Furthermore, both the first limiting guide rail and the second limiting guide rail are guide rod structures; both ends of the first limiting guide rail and both ends of the second limiting guide rail are connected to the column, and both the first limiting guide rail and the second limiting guide rail are arranged at intervals from the bottom surface of the rectangular frame.

[0012] Furthermore, the annular scale line on the measuring nut is located at the end of the outer wall of the measuring nut.

[0013] Furthermore, a rolling bearing with an interference fit is fitted to the outer side of the measuring nut, and the sleeve is fitted to the outer side of the rolling bearing with an interference fit.

[0014] The outer wall of the measuring nut is provided with a first axial limiting part and a second axial limiting part arranged axially at intervals. The first axial limiting part is detachably connected to the measuring nut. The rolling bearing is located between the first axial limiting part and the second axial limiting part. The first axial limiting part and the second axial limiting part cooperate to clamp and position the inner ring of the rolling bearing.

[0015] One end of the sleeve is provided with a limiting ring plate that protrudes inward from its inner sidewall, and the other end of the sleeve is threadedly connected to a fastening sleeve that protrudes inward from its inner sidewall; the limiting ring plate and the fastening sleeve cooperate to clamp and position the outer ring of the rolling bearing.

[0016] Furthermore, a positioning bolt is threaded onto the measuring nut, and the axis of the positioning bolt is arranged radially along the measuring nut.

[0017] Furthermore, the first gripper includes a connecting rod and a limiting rod that are perpendicularly connected to each other, and the end face of the limiting rod away from the connecting rod is the gripping surface; the first gripper and the second gripper have the same structure;

[0018] The two ends of the connecting rod on the first gripper are respectively connected to the first limiting guide rail and the sleeve with its axis parallel to the X-direction measuring screw, and the clamping surface on the first gripper is perpendicular to the X-direction measuring screw; the two ends of the connecting rod on the second gripper are respectively connected to the second limiting guide rail and the sleeve with its axis parallel to the Y-direction measuring screw, and the clamping surface on the second gripper is perpendicular to the Y-direction measuring screw.

[0019] Furthermore, the limiting rod is detachably connected to the connecting rod.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows: It provides an in-situ measuring fixture, which adjusts the positions of the two first jaws on the X-axis measuring screw and the two second jaws on the Y-axis measuring screw by rotating the measuring nut on the X-axis and Y-axis measuring screws. This allows the utility model to clamp and position samples of different shapes and sizes in the horizontal direction. By setting X-axis scale lines on the X-axis measuring screw and annular scale lines on the outer wall of the measuring nut, the position of the measuring nut on the X-axis measuring screw is marked. Similarly, by setting Y-axis scale lines on the Y-axis measuring screw and annular scale lines on the outer wall of the measuring nut, the adjustment accuracy of the measuring nut on the X-axis and Y-axis measuring screws is improved. This ensures the adjustment accuracy of the first jaws on the second jaws, improves the position adjustment and positioning accuracy of the samples during production and experimentation, and enhances the accuracy of sample detection. In addition, the threaded connection between the measuring nut and the X-axis measuring screw forms a self-locking structure, and the threaded connection between the measuring nut and the Y-axis measuring screw forms a self-locking structure. The structure is simple, and after the measuring nut is adjusted, it can ensure the horizontal positioning of the sample, further improving the adjustment and positioning accuracy of the measuring nut on the X-axis and Y-axis measuring screws, and improving the positioning reliability of the device. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the axial side structure of this utility model;

[0022] Figure 2 This is a schematic diagram of the assembly structure of the measuring nut and sleeve on the X-axis measuring screw / Y-axis measuring screw;

[0023] Figure 3 This is an axial sectional view of the assembly structure of the measuring nut and sleeve on the X-axis measuring screw / Y-axis measuring screw;

[0024] Reference numerals: 1-Frame; 11-Rectangular frame; 12-Column; 2-X-direction measuring screw; 21-X-direction scale surface; 22-X-direction scale line; 3-Y-direction measuring screw; 31-Y-direction scale surface; 32-Y-direction scale line; 4-First limiting guide rail; 5-Second limiting guide rail; 61-Measuring nut; 62-Sleeve; 621-Limiting ring plate; 622-Fasting sleeve; 64-Rolling bearing; 65-First axial limiting part; 66-Second axial limiting part; 67-Accommodation space; 71-First gripper; 711-Connecting rod; 712-Limiting rod; 72-Second gripper; 8-Positioning bolt. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0026] As attached Figure 1-3As shown, an in-situ measuring fixture includes a frame 1, characterized in that: the frame 1 is provided with an X-direction measuring screw 2, a Y-direction measuring screw 3, a first limiting guide rail 4 parallel to the X-direction measuring screw 2, and a second limiting guide rail 5 parallel to the Y-direction measuring screw 3; the X-direction measuring screw 2 and the Y-direction measuring screw 3 are arranged perpendicularly to each other; the side wall of the X-direction measuring screw 2 has an X-direction scale surface 21 extending along its axial direction, and the X-direction scale surface 21 has X-direction scale lines 22 parallel to the axis of the X-direction measuring screw 2; the side wall of the Y-direction measuring screw 3 has a Y-direction scale surface 31 extending along its axial direction, and the Y-direction scale surface 31 has Y-direction scale lines 32 parallel to the axis of the Y-direction measuring screw 3. The X-axis measuring screw 2 and the Y-axis measuring screw 3 are each fitted with a threaded measuring nut 61. The outer contour of the measuring nut 61 is circular, and its outer wall has an annular scale line coaxial with it. A sleeve 62 is rotatably connected to the measuring nut 61. The measuring nut 61 has an axial positioning part, which is used to axially position the sleeve 62 on the measuring nut 61. The X-axis measuring screw 2 and the Y-axis measuring screw 3 are each provided with two measuring nuts 61. The sleeves 62 of the two measuring nuts 61 on the X-axis measuring screw 2 are respectively provided with first jaws 71 that are axially slidably connected to the first limiting guide rail 4, and the clamping surfaces of the two first jaws 71 are close to each other. The sleeves 62 of the two measuring nuts 61 on the Y-axis measuring screw 3 are respectively provided with second jaws 72 that are axially slidably connected to the second limiting guide rail 5, and the clamping surfaces of the two second jaws 72 are close to each other.

[0027] The X-axis scale surface 21 will break the thread on the X-axis measuring screw 2, but will not affect the relative movement between the measuring nut 61 and the X-axis measuring screw 2. Similarly, the presence of the Y-axis scale surface 31 will not affect the relative movement between the measuring nut 72 and the Y-axis measuring screw 3. The axial positioning part can be two axially spaced limiting ring plates or a pin structure. For ease of explanation, the axial direction of the X-axis measuring screw 2 is taken as the X-axis, and the axial direction of the Y-axis measuring screw 3 is taken as the Y-axis. The first gripper 71 slides with the first limiting guide rail 4 to circumferentially position the sleeve 62, whose axis is arranged along the X-axis. The second gripper 72 slides with the second limiting guide rail 5 to circumferentially position the sleeve 62, whose axis is arranged along the Y-axis. Thus, the sleeve 62 can only rotate relative to the measuring nut 61 and move axially with the measuring nut 61, but cannot rotate synchronously with the measuring nut 61. Rotating the measuring nut 61 on the X-axis measuring screw 2 causes the measuring nut 61 to drive the sleeve 62 and the first clamp 71 on it to move axially along the X-axis measuring screw 2, thereby adjusting the position of the first clamp 71 in the X-axis; rotating the measuring nut 61 on the Y-axis measuring screw 3 causes the measuring nut 61 to drive the sleeve 62 and the second clamp 72 to move axially along the Y-axis measuring screw 3, thereby adjusting the position of the second clamp 72 in the Y-axis.

[0028] When using this utility model, it needs to be fixed on the positioning surface of the stage of the testing equipment. The X-axis measuring screw 2 and the Y-axis measuring screw 3 are both parallel to the upper positioning surface of the stage. The positions of the first gripper 71 in the X direction and the second gripper 64 in the Y direction are adjusted according to the preset position and size of the sample to be tested on the stage. Specifically, the two measuring nuts 61 on the X-direction measuring screw 2 are rotated to adjust the position of the first gripper 71 so that the distance between the two first grippers 71 is greater than the size of the sample to be tested in the X direction. The two measuring nuts 61 on the Y-direction measuring screw 3 are rotated to adjust the position of the second gripper 72 so that the distance between the two second grippers 72 is greater than the size of the sample in the X direction. The two first grippers 71 and the two second grippers 72 form a receiving space 67 for accommodating the sample to be tested. The sample to be tested is placed in the receiving space 67. The measuring nuts 61 on the X-direction measuring screw 2 are rotated to clamp the sample to be tested in the X direction, and the measuring nuts 61 on the Y-direction measuring screw 3 are rotated to clamp the sample to be tested in the Y direction. The sample to be tested is then horizontally positioned on the stage for testing. The reading obtained by the alignment of the X-axis scale line 22 and the annular scale line on the X-axis measuring screw 61 is called the X-axis reading. The reading obtained by the alignment of the Y-axis scale line 32 and the annular scale line on the Y-axis measuring screw 61 is called the Y-axis reading. The X-axis and Y-axis readings of the measuring screw are recorded. After the initial measurement, the position of the sample in the horizontal direction is changed or the horizontal restriction of the sample is lifted by adjusting the positions of the two first jaws 71 and the two second jaws 64. When in-situ measurement of the sample is required, the position of the measuring nut 61 on the X-axis measuring screw 2 and the Y-axis measuring screw 3 is adjusted according to the recorded X-axis and Y-axis readings, thereby achieving in-situ measurement of the sample. The X-axis scale line 23 and the annular scale line on the measuring nut 61 work together to mark the position of the measuring nut 61 on the X-axis measuring screw 2. The Y-axis scale line 33 and the annular scale line on the outer wall of the measuring nut 61 work together to mark the position of the measuring nut 61 on the Y-axis measuring screw 3. This improves the adjustment accuracy of the measuring nut 61 in the X and Y directions, thereby ensuring the adjustment accuracy of the first gripper 71 and the second gripper 72, improving the position adjustment and positioning accuracy of the sample to be tested during production and experimentation, and improving the detection accuracy of the sample.

[0029] Compared to the in-situ measurement method that manually marks the original position of the sample, the in-situ measurement using this invention eliminates the manual marking process and removes errors associated with manual marking and comparing with manual markings to place the sample, thus improving measurement accuracy. In industrial production, this invention can reduce quality deviations within the same batch of workpieces, improving production quality; in experiments, it can improve the accuracy of experimental results. Furthermore, the threaded connection between the measuring nut 61 and the X-direction measuring screw 2 forms a self-locking structure, as does the threaded connection between the measuring nut 61 and the Y-direction measuring screw 3. This simple structure ensures the horizontal positioning of the sample after the measuring nut 61 is adjusted, improving the adjustment and positioning accuracy of the measuring nut 61 on the X-direction measuring screw 2 and the Y-direction measuring screw 3, and enhancing the positioning reliability of the device.

[0030] The frame 1 is used to integrate the X-axis measuring screw 2, the Y-axis measuring screw 3, the first limiting guide rail 4, and the second limiting guide rail 5 into a whole, and to position the entire device on the platform of the testing equipment 9. The frame 1 can be a combined structure assembled from pipes and plates. Specifically, the frame 1 includes a rectangular frame 11 arranged horizontally, with columns 12 at each of the four corners of the bottom surface of the rectangular frame 11; both ends of the X-axis measuring screw 2 and both ends of the Y-axis measuring screw 3 are mounted on the columns 12, and the X-axis measuring screw 2 and the Y-axis measuring screw 3 are spaced apart from the bottom surface of the rectangular frame 11. The X-axis measuring screw 2 and the Y-axis measuring screw 3 connect two adjacent columns 12, improving the structural stability of the frame 1.

[0031] The first limiting guide rail 4 and the second limiting guide rail 5 can be either guide groove structures or guide rod structures. Preferably, both the first limiting guide rail 4 and the second limiting guide rail 5 are guide rod structures; both ends of the first limiting guide rail 4 and both ends of the second limiting guide rail 5 are connected to the column 12, and both the first limiting guide rail 4 and the second limiting guide rail 5 are spaced apart from the bottom surface of the rectangular frame 11. The first limiting guide rail 4 and the second limiting guide rail 5 also serve to connect two adjacent columns 12, further improving the structural stability of the frame 1.

[0032] Both the X-axis measuring screw 2 and the Y-axis measuring screw 3 are fully threaded screws, expanding the axial adjustment range of the measuring nut 61 on the X-axis measuring screw 2 and the Y-axis measuring screw 3. The X-axis scale surface 21 and the Y-axis scale surface 31 are uniform strip surfaces, which can be arc surfaces or planes. The length direction of the X-axis scale surface 21 is parallel to the axis of the X-axis measuring screw 2, and the length direction of the Y-axis scale surface 31 is parallel to the axis of the Y-axis measuring screw 3. The X-axis scale line 22 is used to mark the position of the measuring nut 61 on the X-axis measuring screw 2. The X-axis scale line 22 and the annular scale line on the measuring nut 61 cooperate to further accurately mark the position of the measuring nut 61 on the X-axis measuring screw 2. The Y-axis scale line 32 is used to mark the position of the measuring nut 61 on the Y-axis measuring screw 3. The Y-axis scale line 32 and the annular scale line on the measuring nut 61 cooperate to further accurately mark the position of the measuring nut 61 on the Y-axis measuring screw 3. The distance between two adjacent graduation lines on the X-axis graduation line 22 and the Y-axis graduation line 32 is generally set to 1 mm. Preferably, the annular graduation line on the measuring nut 61 is located at the end of the outer wall of the measuring nut 61, which facilitates reading the annular graduation line in conjunction with the X-axis graduation line 22 and the annular graduation line in conjunction with the Y-axis graduation line 32, thereby reducing reading errors and further ensuring the sample positioning accuracy.

[0033] The sleeve 62 can be fitted on the outside of the measuring nut 61 or located inside the measuring nut 61. The two can be directly fitted and rotated together, or they can be rotated together through bearings, balls, or other structures. Specifically, a rolling bearing 64 with an interference fit is fitted to the outer side of the measuring nut 61, and a sleeve 62 is fitted to the outer side of the rolling bearing 64 with an interference fit. The outer wall of the measuring nut 61 has a first axial limiting part 65 and a second axial limiting part 66 arranged axially at intervals. The first axial limiting part 65 is detachably connected to the measuring nut 61. The rolling bearing 64 is located between the first axial limiting part 65 and the second axial limiting part 66. The first axial limiting part 65 and the second axial limiting part 66 cooperate to clamp and position the inner ring of the rolling bearing 64. One end of the sleeve 62 has a limiting ring plate 621 protruding inward from its inner sidewall, and the other end of the sleeve 62 is threadedly connected to a fastening sleeve 622 protruding inward from its inner sidewall. The limiting ring plate 621 and the fastening sleeve 622 cooperate to clamp and position the outer ring of the rolling bearing 64. To avoid relative friction between the measuring nut 61 and the sleeve 62 during rotation, reduce wear on the measuring nut 61 and the sleeve 62, ensure measurement and positioning accuracy, and extend the service life of the equipment.

[0034] Preferably, a positioning bolt 8 is threaded onto the measuring nut 61, and the axis of the positioning bolt 8 is arranged radially along the measuring nut 61. After the measuring nut 61 on the X-direction measuring screw 2 is adjusted, the positioning bolt 8 is rotated to press against the X-direction measuring screw 2, preventing the measuring nut 61 on the X-direction measuring screw 2 from rotating; after the measuring nut 61 on the Y-direction measuring screw 3 is adjusted, the positioning bolt 8 is rotated to press against the Y-direction measuring screw 3, preventing the measuring nut 61 on the Y-direction measuring screw 3 from rotating. This improves the measurement accuracy and positioning accuracy of the device, and enhances the stability and reliability of the device.

[0035] Two first grippers 71 are used to clamp and position the sample to be tested in the X direction, and two second grippers 72 are used to clamp and position the sample to be tested in the Y direction. Preferably, the first gripper 71 includes a connecting rod 711 and a limiting rod 712 connected perpendicularly to each other, and the end face of the limiting rod 712 away from the connecting rod 711 is the clamping surface; the first gripper 71 and the second gripper 72 have the same structure; the two ends of the connecting rod 711 on the first gripper 71 are respectively connected to the first limiting guide rail 4 and the sleeve 62 whose axis is parallel to the X-direction measuring screw 2, and the clamping surface on the first gripper 71 is perpendicular to the X-direction measuring screw 2; the two ends of the connecting rod 711 on the second gripper 72 are respectively connected to the second limiting guide rail 5 and the sleeve 62 whose axis is parallel to the Y-direction measuring screw 3, and the clamping surface on the second gripper 72 is perpendicular to the Y-direction measuring screw 3. The structure is simple and easy to manufacture. The connecting rod 711 and the limiting rod 712 can be a single integral structure, or a combined structure assembled by welding, bolting, pinning, or other methods. As a further preferred embodiment, the limiting rod 712 is detachably connected to the connecting rod 711, allowing for the replacement of connecting rods of different lengths and with different clamping surfaces when measuring samples of different shapes, thus providing greater convenience and flexibility.

[0036] The embodiments described herein are preferred embodiments of this utility model and are not intended to limit the scope of protection of this utility model. Therefore, all equivalent changes made to the structure, shape, and principle of this utility model should be included within the scope of protection of this utility model.

Claims

1. An in-situ measurement jig comprising a frame (1) characterised in that: The frame (1) is provided with an X-direction measuring screw (2), a Y-direction measuring screw (3), a first limiting guide rail (4) parallel to the X-direction measuring screw (2), and a second limiting guide rail (5) parallel to the Y-direction measuring screw (3). The X-direction measuring screw (2) and the Y-direction measuring screw (3) are arranged perpendicular to each other. The X-axis measuring screw (2) has an X-axis scale surface (21) extending along its axial direction on its side wall, and an X-axis scale line (22) parallel to the axis of the X-axis measuring screw (2) is provided on the X-axis scale surface (21); the Y-axis measuring screw (3) has a Y-axis scale surface (31) extending along its axial direction on its side wall, and a Y-axis scale line (32) parallel to the axis of the Y-axis measuring screw (3) is provided on the Y-axis scale surface (31). Both the X-axis measuring screw (2) and the Y-axis measuring screw (3) are fitted with measuring nuts (61) that are threadedly connected to them. The outer contour of the cross-section of the measuring nut (61) is circular and its outer side wall is provided with an annular scale line coaxial with it. A sleeve (62) is coaxially rotatably connected to the measuring nut (61). The measuring nut (61) is provided with an axial positioning part, which is used to axially position the sleeve (62) on the measuring nut (61). Both the X-axis measuring screw (2) and the Y-axis measuring screw (3) are provided with two measuring nuts (61); the sleeves (62) of the two measuring nuts (61) on the X-axis measuring screw (2) are respectively provided with first grippers (71) that are axially slidably connected to the first limiting guide rail (4), and the clamping surfaces of the two first grippers (71) are close to each other; the sleeves (62) of the two measuring nuts (61) on the Y-axis measuring screw (3) are respectively provided with second grippers (72) that are axially slidably connected to the second limiting guide rail (5), and the clamping surfaces of the two second grippers (72) are close to each other.

2. The in-situ measurement fixture of claim 1, wherein: The frame (1) includes a rectangular frame (11) arranged in a horizontal direction, and each of the four corners of the bottom surface of the rectangular frame (11) is provided with a column (12); Both ends of the X-direction measuring screw (2) and both ends of the Y-direction measuring screw (3) are mounted on the column (12), and both the X-direction measuring screw (2) and the Y-direction measuring screw (3) are arranged at intervals from the bottom surface of the rectangular frame (11).

3. The in-situ measuring fixture according to claim 2, characterized in that: Both the first limiting guide rail (4) and the second limiting guide rail (5) are guide rod structures; both ends of the first limiting guide rail (4) and both ends of the second limiting guide rail (5) are connected to the column (12), and both the first limiting guide rail (4) and the second limiting guide rail (5) are arranged at intervals from the bottom surface of the rectangular frame (11).

4. The in-situ measuring fixture according to claim 1, characterized in that: The annular scale line on the measuring nut (61) is located at the end of the outer wall of the measuring nut (61).

5. The in-situ measuring fixture according to any one of claims 1-4, characterized in that: The measuring nut (61) is fitted with an interference fit rolling bearing (64) on its outer side, and the sleeve (62) is fitted with the outer side of the rolling bearing (64) and the two are interference fit. The outer side wall of the measuring nut (61) is provided with a first axial limiting part (65) and a second axial limiting part (66) arranged axially at intervals. The first axial limiting part (65) is detachably connected to the measuring nut (61). The rolling bearing (64) is located between the first axial limiting part (65) and the second axial limiting part (66). The first axial limiting part (65) and the second axial limiting part (66) cooperate to clamp and position the inner ring of the rolling bearing (64). One end of the sleeve (62) is provided with a limiting ring plate (621) protruding inward from its inner sidewall, and the other end of the sleeve (62) is threadedly connected to a fastening sleeve (622) protruding inward from its inner sidewall; the limiting ring plate (621) and the fastening sleeve (622) cooperate to clamp and position the outer ring of the rolling bearing (64).

6. The in-situ measuring fixture according to claim 1, characterized in that: The measuring nut (61) is threaded with a positioning bolt (8), the axis of which is arranged radially along the measuring nut (61).

7. The in-situ measuring fixture according to claim 3, characterized in that: The first gripper (71) includes a connecting rod (711) and a limiting rod (712) that are perpendicularly connected to each other. The end face of the limiting rod (712) away from the connecting rod (711) is the gripping surface. The first gripper (71) and the second gripper (72) have the same structure. The two ends of the connecting rod (711) on the first jaw (71) are respectively connected to the first limiting guide rail (4) and the sleeve (62) whose axis is parallel to the X-direction measuring screw (2). The clamping surface on the first jaw (71) is perpendicular to the X-direction measuring screw (2). The two ends of the connecting rod (711) on the second jaw (72) are respectively connected to the second limiting guide rail (5) and the sleeve (62) whose axis is parallel to the Y-direction measuring screw (3). The clamping surface on the second jaw (72) is perpendicular to the Y-direction measuring screw (3).

8. The in-situ measuring fixture according to claim 7, characterized in that: The limiting rod (712) is detachably connected to the connecting rod (711).

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