Fastener length comparison instrument

Abstract

The utility model relates to the technical field of fastener detection equipment, in particular to a fastener length comparison instrument. Comprising a measuring frame body, and the measuring frame body comprises a bottom plate, and a first end panel and a second end panel which are vertically arranged at two ends of the bottom plate; the fastener length comparison instrument further comprises an ejector rod arranged on the first end face plate, a dial indicator arranged on the second end face plate and a width adjusting assembly of the bottom plate, the width adjusting assembly comprises a first adjusting piece and a second adjusting piece, a containing gap is formed in the butt joint position of the first adjusting piece and the second adjusting piece, and the fastener is horizontally placed in the containing gap. The first adjusting piece and the second adjusting piece can move in the width direction of the bottom plate, the width of the containing gap changes, and the wider the containing gap is, the lower the height of the central axis of the fastener to be measured is. The ejector rod and the measuring rod move in the horizontal direction, so that the fastener length comparison instrument is suitable for measuring fasteners of various specifications with different diameters and lengths, and the problem that existing equipment needs to be equipped with multiple pieces of equipment for different specifications is solved.

Description

Technical Field

[0001] This utility model relates to the field of fastener testing equipment technology, and in particular to a fastener length comparator. Background Technology

[0002] Fasteners (such as bolts, screws, and studs) are critical components in mechanical connections, and the finished product proof load test is an important means of evaluating their load-bearing capacity and manufacturing quality. This test involves applying a standard-specified axial proof load to the fastener on a tensile testing machine and maintaining it for a certain period to detect its deformation under load and determine whether it meets relevant standard requirements. One of the key indicators of the test is the change in the fastener's length before and after the proof load, which needs to be measured with high precision; the allowable error is typically only ±12.5 μm.

[0003] Among existing testing methods, commonly used measuring tools include micrometers and length comparators. Handheld micrometers, due to their operation, are prone to misalignment when measuring long rod-shaped fasteners, leading to significant measurement errors. Furthermore, multiple measuring devices with different ranges are required for samples of different specifications and lengths, which is not only costly and complex to operate, but also makes it difficult to guarantee the repeatability and stability of the measurement results.

[0004] Another commonly used device is the length comparator, primarily designed for measuring the length changes of concrete or mortar specimens. These length comparators are typically fixed to samples of a specific size in terms of structure and clamping method, lacking adaptability to fasteners of diverse specifications. Furthermore, their dimensions and models are usually customized for a particular type of standard sample, resulting in poor applicability and limited versatility in fastener testing scenarios.

[0005] Therefore, the measurement of length change after the guaranteed load test of finished fasteners still has shortcomings in terms of measurement accuracy, adaptability and measurement efficiency, and is inconvenient in practical applications. Utility Model Content

[0006] To address the shortcomings of the existing technology, this utility model provides a fastener length comparator that is applicable to fasteners of various sizes, simple to operate, and accurate in measurement.

[0007] This utility model provides a fastener length comparator, comprising:

[0008] The measuring frame includes a horizontally arranged base plate and a first end panel and a second end panel arranged vertically at both ends of the base plate;

[0009] A top rod is disposed on the first end panel, and the top rod is parallel to the bottom plate;

[0010] A dial indicator is mounted on the second end panel, with the dial of the dial indicator located on the outside of the second end panel and the measuring rod of the dial indicator passing through the second end panel.

[0011] The upright projections of part of the top rod and part of the measuring rod are located on the base plate;

[0012] in,

[0013] A width adjustment assembly is provided on the upper surface of the base plate. The width adjustment assembly includes a first adjustment member and a second adjustment member arranged opposite to each other. A receiving gap is formed at the joint of the first adjustment member and the second adjustment member. The fastener to be measured is placed horizontally in the receiving gap. Both the first adjustment member and the second adjustment member can move along the width direction of the base plate. When the first adjustment member or / and the second adjustment member move, the width of the receiving gap changes accordingly, so that the central axis of the fastener to be measured is collinear with the central axis of the measuring rod.

[0014] In this technical solution, by adjusting the positions of the first adjusting member and the second adjusting member on the base plate, the size of the accommodating gap between the first adjusting member and the second adjusting member is adjusted. The wider the accommodating gap, the lower the height of the center axis of the fastener to be measured; the narrower the accommodating gap, the higher the height of the center axis of the fastener to be measured. This allows for the accommodating of fasteners of different diameters and the measurement of their length.

[0015] In some embodiments of this application, the base plate has an adjustment groove that extends along the width direction of the base plate, the bottom of the first adjustment member has a first threaded hole extending along its height direction, and the bottom of the second adjustment member has a second threaded hole extending along its height direction.

[0016] The first bolt passes through the adjusting groove and the first threaded hole from bottom to top and engages with the first adjusting component.

[0017] The second bolt passes through the adjusting groove and the second threaded hole from bottom to top, and mates with the second adjusting component.

[0018] Adjusting the first bolt and the second bolt can respectively adjust the relative positions of the first adjusting member and the second adjusting member in the adjusting groove, thereby adjusting the size of the receiving gap.

[0019] In some embodiments of this application, there are at least two adjustment components, which are evenly distributed along the length of the base plate to ensure that the fastener to be measured is placed securely.

[0020] In some embodiments of this application, the first adjusting member is a triangular prism structure, including two parallel first bottom surfaces, intersecting first and second side surfaces, the two first bottom surfaces being perpendicular to the base plate, the first side surfaces being located on the base plate, and the second side surfaces being close to the second adjusting member;

[0021] The first adjusting member also has a receiving groove that extends upward from the first side to the second side. At least part of the second adjusting member moves horizontally within the receiving groove to adjust the width of the receiving gap.

[0022] In some embodiments of this application, the second adjusting member is a triangular prism structure, including two parallel second bottom surfaces, an intersecting third side surface and a fourth side surface, the two second bottom surfaces being perpendicular to the base plate, the third side surface being located on the base plate, and the fourth side surface being close to the first adjusting member;

[0023] The distance between the two second bottom surfaces is adapted to the width of the receiving groove so that the second adjusting member can move within the receiving groove;

[0024] The second side and the fourth side form the receiving gap.

[0025] In some embodiments of this application, the angle between the first side and the second side is an acute angle, and the angle between the third side and the fourth side is an acute angle;

[0026] The angle between the second side and the fourth side is an obtuse angle, which facilitates the placement of fasteners of different specifications to be measured.

[0027] In some embodiments of this application, the first end panel has a horizontal first mounting hole, the top of the first end panel has a vertically downward extending first fixing hole, and the bottom of the first fixing hole communicates with the first mounting hole.

[0028] The top rod passes through the first mounting hole, and multiple top rod adjustment holes are evenly distributed along the axial direction of the top rod. The first positioning bolt passes through the first fixing hole and is fastened to the top rod adjustment holes at different positions to adjust the distance between the top rod and the measuring rod, so that fasteners of different lengths can be fixed between the measuring rod and the top rod for measurement.

[0029] In some embodiments of this application, the second end panel has a horizontal second mounting hole, and the top of the second end panel has a vertically downward extending second fixing hole, the bottom of the second fixing hole communicating with the second mounting hole;

[0030] The measuring rod passes through the second mounting hole, and multiple measuring adjustment holes are evenly distributed along the axial direction of the measuring rod. The second positioning bolt passes through the second fixing hole and is fastened to the measuring adjustment holes at different positions to adjust the distance between the measuring rod and the top rod, so that fasteners of different lengths can be fixed between the measuring rod and the top rod for measurement.

[0031] In some embodiments of this application, the centers of the first mounting hole and the second mounting hole are at the same distance from the base plate, the central axis of the top rod is collinear with the central axis of the measuring rod, and also collinear with the central axis of the fastener to be measured, so as to securely clamp the fastener to be measured and accurately measure its length.

[0032] Based on the above technical solution, by adjusting the positions of the first adjusting member and the second adjusting member on the base plate, the size of the receiving gap between the first adjusting member and the second adjusting member is adjusted. The wider the receiving gap, the lower the height of the central axis of the fastener to be measured; the narrower the receiving gap, the higher the height of the central axis of the fastener to be measured. This makes the central axis of the top rod, the central axis of the measuring rod, and the central axis of the fastener to be measured collinear, thereby enabling accurate measurement of fasteners of different diameters.

[0033] Both the top rod and the measuring rod of the dial indicator can move horizontally, which can stably clamp fasteners of different lengths. This makes the fastener length comparator suitable for measuring fasteners of various specifications with different diameters and lengths, solving the problem that existing equipment requires multiple devices for different specifications.

[0034] The measurement operation is simple, highly accurate, and improves the efficiency of the test operation. Attached Figure Description

[0035] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0036] Figure 1 This is a three-dimensional structural diagram of the fastener length comparator according to an embodiment of the present utility model;

[0037] Figure 2 This is a schematic diagram of the measuring frame according to an embodiment of the present utility model;

[0038] Figure 3 This is a schematic diagram showing the positional relationship between the first adjusting member and the second adjusting member in an embodiment of the present utility model.

[0039] Figure 4 This is a bottom view of the first adjusting member according to an embodiment of the present utility model;

[0040] Figure 5 This is a bottom view of the second adjusting member according to an embodiment of the present utility model;

[0041] Figure 6 This is a bottom view of the measuring frame according to an embodiment of the present utility model.

[0042] In the picture,

[0043] 10. Measuring frame; 11. Base plate; 111. Adjustment groove; 12. First end panel; 121. First mounting hole; 122. First fixing hole; 123. First positioning bolt; 13. Second end panel; 131. Second mounting hole; 132. Second fixing hole; 133. Second positioning bolt; 20. Top rod; 30. Dial indicator; 31. Dial; 32. Measuring rod; 40. Width adjustment assembly; 41. First adjusting component; 411. First bottom surface; 412. First side surface; 4121. First threaded hole; 413. Second side surface; 414. Receiving groove; 415. First bolt; 42. Second adjusting component; 421. Second bottom surface; 422. Third side surface; 4221. Second threaded hole; 423. Fourth side surface; 424. Second bolt; 43. Receiving gap. Detailed Implementation

[0044] The technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0045] In the description of this utility model, it should be understood that the terms "center", "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0046] The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature.

[0047] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0048] As attached Figures 1-6 As shown, the fastener length comparator of this embodiment includes:

[0049] The measuring frame 10 includes a horizontally arranged base plate 11 and a first end panel 12 and a second end panel 13 arranged vertically at both ends of the base plate 11.

[0050] A push rod 20 is provided on the first end panel 12. The push rod 20 is parallel to the bottom plate 11. Part of the structure of the push rod 20 is located on the outside of the first end panel 12, and another part is located on the inside of the first end panel 12.

[0051] A dial indicator 30 is mounted on the second end panel 13. The dial 31 of the dial indicator 30 is located on the outside of the second end panel 13, and the measuring rod 32 of the dial indicator 30 passes through the second end panel 13. Part of the measuring rod 32 is located on the outside of the second end panel 13, and the other part is located on the inside of the second end panel 13. The two ends of the fastener to be measured are fixed by the end of the top rod 20 located on the inside of the first end panel 12 and the end of the measuring rod located on the inside of the second end panel 13, respectively. The dial indicator measures the length of the fastener to be measured.

[0052] Two width adjustment components 40 are evenly arranged on the upper surface of the base plate 11. Each width adjustment component 40 includes a first adjustment member 41 and a second adjustment member 42 arranged opposite to each other. A receiving gap 43 is formed at the joint of the first adjustment member 41 and the second adjustment member 42. In this embodiment, as shown... Figure 1 As shown, the accommodating gap 43 is a V-shaped gap. The first adjusting member 41 and the second adjusting member 42 can both move along the width direction of the base plate 11. The fastener to be measured is placed horizontally in the accommodating gap 43. The width of the accommodating gap 43 changes accordingly as the first adjusting member 41 and / or the second adjusting member 42 moves, so that fasteners of different diameters can be placed.

[0053] like Figure 2 As shown, the base plate 11 has two adjustment grooves 111. The adjustment grooves 111 extend along the width direction of the base plate. The first adjustment member 41 and the second adjustment member 42 can both move along the adjustment grooves to adjust the width of the accommodating gap.

[0054] Specifically, such as Figure 3As shown, the first adjusting member 41 is a triangular prism structure, including two parallel first bottom surfaces 411, a first side surface 412 and a second side surface 413 that connect the two first bottom surfaces 411 and intersect each other. When the first adjusting member 41 is placed on the base plate 11, the two first bottom surfaces 411 are perpendicular to the base plate 11, the first side surface 412 is located on the upper surface of the base plate 11, and the second side surface 413 is close to the second adjusting member 42.

[0055] The first adjusting member 41 also has a receiving groove 414, which extends upward from the first side 412 to the second side 413. At least part of the second adjusting member 42 moves horizontally within the receiving groove 414, and the relative positions of the first adjusting member 41 and the second adjusting member 42 change to adjust the width of the receiving gap 43.

[0056] The first side 412 has an upwardly extending first threaded hole 4121. The first bolt 415 passes through the adjustment groove 111 and the first threaded hole 4121 from bottom to top and is fastened to the first adjusting member. When it is necessary to adjust the position of the first adjusting member 41, the first bolt 415 is loosened and the first adjusting member 41 moves along the adjustment groove 111. When it moves to a suitable position, the first bolt 415 is tightened to fix the first adjusting member 41 in that position.

[0057] The second adjusting member 42 is a right-angled triangular prism structure, including two parallel second base surfaces 421, a third side surface 422 connecting the two second base surfaces 421 and intersecting therewith, and a fourth side surface 423. The third side surface 422 is the plane containing one leg of the right triangle, and the fourth side surface 423 is the plane containing the hypotenuse of the right triangle. When the second adjusting member 42 is placed on the base plate 11, the two second base surfaces 421 are perpendicular to the base plate 11, the third side surface 422 is located on the upper surface of the base plate 11, and the fourth side surface 423 is close to the second side surface 413 of the first adjusting member 41.

[0058] The distance between the two second bottom surfaces 421 is adapted to the width of the receiving groove 414, the second side surface 413 and the fourth side surface 423 form a receiving gap 43, and the second adjusting member 42 moves within the receiving groove 414 to adjust the width of the receiving gap 43.

[0059] The third side 422 has an upwardly extending second threaded hole 4221. The second bolt 424 passes through the adjustment groove 111 and the second threaded hole 4221 from bottom to top and is fastened to the second adjusting member 42. When it is necessary to adjust the position of the second adjusting member 42, the second bolt 424 is loosened and the second adjusting member 42 moves along the adjustment groove 111. When it moves to the appropriate position, the second bolt 424 is tightened to fix the second adjusting member 42 in that position.

[0060] Furthermore, the height of the receiving groove 414 is less than or equal to the height of the plane containing the other right-angled side of the second adjusting member 42, so that the second adjusting member 42 can move relative to each other within the receiving groove 414, and the second side 413 and the fourth side 423 can form a receiving gap 43.

[0061] like Figure 3 As shown, the angle between the first side 412 and the second side 413 is an acute angle, and the angle between the third side 422 and the fourth side 423 is also an acute angle. Then, the angle between the second side 413 and the fourth side 423 is made obtuse, which facilitates the placement of fasteners of different diameters to be measured, and at the same time makes the central axis of the fastener to be measured collinear with the axis of the measuring rod 32.

[0062] See also Figure 2 The first end panel 12 has a horizontal first mounting hole 121, and the top of the first end panel 12 has a vertically downward extending first fixing hole 122, the bottom of the first fixing hole 122 being connected to the first mounting hole 121.

[0063] The push rod 20 passes through the first mounting hole 121, and multiple push rod adjustment holes (not shown in the figure) are evenly distributed along the axial direction of the push rod 20. The first positioning bolt 123 passes through the first fixing hole 122 and is fastened to the push rod adjustment holes at different positions to adjust the length of the push rod 20 located inside the first end panel 12, thereby adjusting the horizontal distance between the push rod 20 and the measuring rod 32, so that fasteners of different lengths can be fixed between the measuring rod 32 and the push rod 20.

[0064] Similarly, the second end panel 13 has a horizontal second mounting hole 131, and the top of the second end panel 13 has a vertically downward extending second fixing hole 132. The bottom of the second fixing hole 132 communicates with the second mounting hole 131. The measuring rod 32 passes through the second mounting hole 131, and multiple measuring adjustment holes (not shown in the figure) are also evenly distributed along the axial direction of the measuring rod 32. The second positioning bolt 133 passes through the second fixing hole 132 and is fastened to the measuring adjustment holes at different positions to adjust the distance of the measuring rod 32 on the inner side of the second end panel 13 and adjust the horizontal distance between the measuring rod 32 and the top rod 20 to measure fasteners of different lengths.

[0065] The center of the first mounting hole 121 and the second mounting hole 131 are at the same distance from the base plate 11, so that the axis of the measuring rod 32 and the center axis of the top rod 20 are collinear, and are collinear with the center axis of the fastener to be measured, so as to accurately measure its length.

[0066] When measuring the length of a fastener, the first bolt 415 and the second bolt 424 are rotated according to the diameter of the fastener to adjust the relative positions of the first adjusting member 41 and the second adjusting member 42 in the adjusting groove 111. The width of the V-shaped receiving gap 43 between the first adjusting member 41 and the second adjusting member 42 is adjusted to a suitable size to ensure that the fastener to be measured can be stably placed in the receiving gap 43, and that the central axis of the fastener to be measured is collinear with the central axis of the measuring rod 32 and the central axis of the top rod 20.

[0067] Adjust the distance between the top rod 20 and the measuring rod 32 so that the ends of the top rod 20 and the measuring rod 32 can press against both ends of the fastener to be measured. Tighten the first positioning bolt 123 to make it securely fit with the top rod adjustment hole at that position. Tighten the second positioning bolt 133 to make it securely fit with the measuring rod adjustment hole at that position. The length displayed by the dial indicator is the length of the fastener to be measured.

[0068] First, measure and record the length of the fastener before the load test. Next, install the fastener on a tensile testing machine, apply an axial load according to the test standard, and hold for 15 seconds. After loading, place the fastener again on the fastener length comparator of this embodiment and measure the length after loading. Calculate the difference between the two measurements and determine if it is within the allowable error range of ±12.5 μm. If it is within the allowable error range, the length before and after loading is considered to be the same.

[0069] Actual testing has shown that this device, once completed, can achieve its intended purpose. One device can measure fasteners of various specifications, and its measurement stability and accuracy meet the testing requirements, effectively improving the measurement efficiency and accuracy of fastener load-bearing tests.

[0070] By adjusting the positions of the first and second adjusting components on the base plate, the size of the accommodating gap between the first and second adjusting components can be adjusted. The wider the accommodating gap, the lower the height of the center axis of the fastener to be measured; the narrower the accommodating gap, the higher the height of the center axis of the fastener to be measured. This ensures that the center axis of the top rod, the center axis of the measuring rod, and the center axis of the fastener to be measured are collinear, thereby enabling accurate measurement of fasteners of different diameters. Both the top rod and the measuring rod of the dial indicator can move horizontally, allowing for stable clamping of fasteners of different lengths. This makes the fastener length comparator suitable for measuring various specifications of fasteners with different diameters and lengths, solving the problem that existing equipment requires multiple devices for different specifications.

[0071] The measurement operation is simple, highly accurate, and improves the efficiency of the test operation.

[0072] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0073] The above embodiments are only used to illustrate the technical solution of this utility model and not to limit it; although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this utility model or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the technical solution claimed by this utility model.

Claims

1. A fastener length comparator, characterized in that: include: The measuring frame includes a horizontally arranged base plate and a first end panel and a second end panel arranged vertically at both ends of the base plate; A top rod is disposed on the first end panel, and the top rod is parallel to the bottom plate; A dial indicator is mounted on the second end panel, with the dial of the dial indicator located on the outside of the second end panel and the measuring rod of the dial indicator passing through the second end panel. The upright projections of part of the top rod and part of the measuring rod are located on the base plate; in, The upper surface of the base plate is provided with a width adjustment assembly, which includes a first adjustment member and a second adjustment member arranged opposite to each other. The first adjustment member and the second adjustment member form a receiving gap at their joint. The fastener to be measured is placed horizontally in the receiving gap. Both the first adjustment member and the second adjustment member can move along the width direction of the base plate. As the first adjustment member and / or the second adjustment member move, the width of the receiving gap changes accordingly, so that the central axis of the fastener to be measured is collinear with the central axis of the measuring rod.

2. The fastener length comparator according to claim 1, characterized in that, An adjustment groove is formed on the base plate, extending along the width direction of the base plate. A first threaded hole extending along the height direction is formed at the bottom of the first adjustment member, and a second threaded hole extending along the height direction is formed at the bottom of the second adjustment member. The first bolt passes through the adjusting groove and the first threaded hole from bottom to top and engages with the first adjusting component. The second bolt passes through the adjusting groove and the second threaded hole from bottom to top, and engages with the second adjusting component. Adjusting the first bolt and the second bolt can respectively adjust the relative positions of the first adjusting member and the second adjusting member within the adjusting groove.

3. The fastener length comparator according to claim 1, characterized in that, There are at least two adjustment components, which are evenly distributed along the length of the base plate.

4. The fastener length comparator according to claim 1, characterized in that, The first adjusting member is a triangular prism structure, including two parallel first bottom surfaces, intersecting first and second side surfaces, the two first bottom surfaces being perpendicular to the base plate, the first side surfaces being located on the base plate, and the second side surfaces being close to the second adjusting member; The first adjusting member also has a receiving groove that extends upward from the first side to the second side. At least part of the second adjusting member moves horizontally within the receiving groove to adjust the width of the receiving gap.

5. The fastener length comparator according to claim 4, characterized in that, The second adjusting member is a triangular prism structure, including two parallel second bottom surfaces, intersecting third and fourth side surfaces, the two second bottom surfaces being perpendicular to the base plate, the third side surface being located on the base plate, and the fourth side surface being close to the first adjusting member; The distance between the two second bottom surfaces is adapted to the width of the receiving groove so that the second adjusting member can move within the receiving groove; The second side and the fourth side form the receiving gap.

6. The fastener length comparator according to claim 5, characterized in that, The angle between the first side and the second side is an acute angle, and the angle between the third side and the fourth side is an acute angle; The angle between the second side and the fourth side is an obtuse angle.

7. The fastener length comparator according to claim 1, characterized in that, The first end panel has a horizontal first mounting hole, and the top of the first end panel has a vertically downward extending first fixing hole, the bottom of the first fixing hole communicating with the first mounting hole. The top rod passes through the first mounting hole, and multiple top rod adjustment holes are evenly distributed along the axial direction of the top rod. The first positioning bolt passes through the first fixing hole and is fastened to the top rod adjustment holes at different positions to adjust the distance between the top rod and the measuring rod.

8. The fastener length comparator according to claim 7, characterized in that, The second end panel has a horizontal second mounting hole, and the top of the second end panel has a vertically downward extending second fixing hole, the bottom of which communicates with the second mounting hole. The measuring rod passes through the second mounting hole, and multiple measuring adjustment holes are evenly distributed along the axial direction of the measuring rod. The second positioning bolt passes through the second fixing hole and is fastened to the measuring adjustment holes at different positions to adjust the distance between the measuring rod and the top rod.

9. The fastener length comparator according to claim 8, characterized in that, The centers of the first mounting hole and the second mounting hole are at the same distance from the base plate. The central axis of the top rod is collinear with the central axis of the measuring rod and also with the central axis of the fastener to be measured.

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