Arc radius measuring tool

Abstract

The utility model belongs to the technical field of measuring tools, and discloses an arc radius measuring tool. The tool comprises a first measuring piece and a second measuring piece, the first measuring piece comprises a first supporting leg, a second supporting leg and an angle measuring disc, the head end of the first supporting leg and the head end of the second supporting leg are hinged to a hinge point, and the tail end of the first supporting leg can abut against and be fixedly arranged on the arc-shaped surface of the arc-shaped product. The tail end of the second supporting leg can slide around the hinge point and fit the arc-shaped surface of the arc-shaped product, the extension lengths of the first supporting leg and the second supporting leg from the head end to the tail end are the same, at least one of the first supporting leg and the second supporting leg is set to be capable of indicating the extension length, and the angle measuring disc is arranged at the hinge point and can measure the included angle between the first supporting leg and the second supporting leg; the second measuring piece is arranged on the second supporting leg and can measure the arc length between the tail end of the first supporting leg and the tail end of the second supporting leg. Through the above arrangement, the arc radius measuring tool can be suitable for products with different arc lengths, and the measuring result is accurate.

Description

Technical Field

[0001] The utility model relates to the technical field of measuring tools, in particular to a circular arc radius measuring tool. Background Art

[0002] When measuring the radius of arc parts, hoses, tooling and other products, the prior art often uses three methods for measurement: (1) using a radius arc ruler of a specific specification, on which the arc length corresponding to different arc radii is engraved; (2) using a radius gauge to measure the chord length between the two ends of the product, and the length from the chord bisector to the middle of the product, and then using the chord length formula to calculate the radius; (3) using a drawing tool to intersect the two perpendicular bisectors of the chord length, the intersection is the center of the circle, and the radius of the product is deduced from this.

[0003] However, measurement methods (1) and (2) require the use of radius arc rulers and radius gauges of different sizes to accommodate products of different radius sizes. Moreover, measurement methods (1), (2) and (3) all have minimum radius restrictions, which results in weak adaptability of the measuring tools and a narrow range of use.

[0004] Therefore, there is an urgent need for an arc radius measurement tool to solve the problems existing in the prior art. Utility Model Content

[0005] The utility model aims to provide a circular arc radius measuring tool, which can be applicable to the measurement of various circular arc radius products, has a wider range of use, and is easy to carry.

[0006] To achieve this purpose, the utility model adopts the following technical solutions:

[0007] An arc radius measuring tool is used to measure the radius of an arc-shaped product, comprising: a first measuring piece, the first measuring piece comprising a first leg, a second leg and a protractor, the head end of the first leg and the head end of the second leg are hinged at a hinge point, the tail end of the first leg can abut and be fixed on the arc surface of the arc-shaped product, the tail end of the second leg can slide around the hinge point and fit the arc surface of the arc-shaped product, the first leg and the second leg have the same extension length from the head end to the tail end, and at least one of the two is configured to indicate the extension length, the protractor is disposed at the hinge point, and the protractor is provided with an angle scale and is used to measure the current angle between the first leg and the second leg; a second measuring piece, the second measuring piece is disposed on the second leg, and the second measuring piece can measure the arc length between the tail end of the first leg and the tail end of the second leg.

[0008] Preferably, the second measuring piece is a roller measure; or, the second measuring piece is a tape measure, the handle of the tape measure is arranged at the tail end of one of the first leg and the second leg, and the end of the tape measure is hooked at the tail end of the other of the first leg and the second leg.

[0009] Preferably, the first measuring member is an angle ruler.

[0010] Preferably, the arc radius measuring tool further comprises a fixing member, which is connected to the first support leg and can fix the first support leg on the arc surface of the arc-shaped product.

[0011] Preferably, the fixing member includes a first rod, a second rod and a third rod, the two ends of the first rod are respectively connected to the second rod and the first support leg, and the end of the second rod away from the first rod is connected to the third rod, so that the fixing member has a U-shaped structure, and the third rod and the first rod are located on arc surfaces on different sides of the arc-shaped product to cooperate with each other to clamp the arc-shaped product.

[0012] Preferably, the first rod comprises a first rod body, a first threaded connection column and a first nut, the first rod body is connected to the second rod, and the first threaded connection column is protruding from the outer edge of the first rod body, and the first nut is threadedly connected to the first threaded connection column;

[0013] A first assembly hole is formed at the bottom end of the first support leg, and the first threaded connection column is passed through the first assembly hole and threadedly connected to the first nut, so that the first support leg is clamped between the first nut and the first rod body.

[0014] Preferably, the first assembly hole is an arc-shaped hole.

[0015] Preferably, the second rod comprises a second rod body, a second threaded connection column and a second nut, the second rod body is connected to the third rod, and the outer edge of the second rod body is protrudingly provided with the second threaded connection column, and the second nut is threadedly connected to the second threaded connection column;

[0016] The first rod body is provided with a second assembly hole, the second threaded connection column is passed through the second assembly hole and is threadedly connected to the second nut, so that the first rod body is clamped between the second nut and the second rod body.

[0017] Preferably, the third rod comprises a third rod body, a third threaded connection column and a third nut, the third rod body is connected to the second rod body, and the outer edge of the third rod body is protrudingly provided with the third threaded connection column, and the third nut is threadedly connected to the third threaded connection column;

[0018] The first rod body is provided with a third assembly hole, the third threaded connection column is passed through the third assembly hole and is threadedly connected to the third nut, so that the first rod body is clamped between the third nut and the third rod body.

[0019] Preferably, the fixing member further comprises a support block, and the support block is sandwiched between the first rod and the arc surface of the arc-shaped product, and between the third rod and the arc surface of the arc-shaped product.

[0020] The arc radius measuring tool provided by the utility model has the following beneficial effects: when in use, the first leg is firstly abutted and fixed on the arc-shaped product, and the second leg is controlled to slide along the arc surface. When there is a gap between the second leg and the first leg, the angle plate can accurately measure the current angle between the first leg and the second leg, and the second measuring piece can accurately measure the arc length between the tail end of the first leg and the tail end of the second leg, and then the arc length formula is used to deduce the radius of the arc-shaped product. Through the arrangement of the first measuring piece and the second measuring piece, the arc radius measuring tool can be applied to products of different arc length sizes, and the measurement results are accurate and reliable, while the operation is convenient and simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an axonometric diagram after the arc radius measuring tool provided by the embodiment of the utility model is connected to the arc-shaped product;

[0022] Figure 2 It is a front view of the arc radius measuring tool provided by the embodiment of the utility model after being connected to the arc-shaped product;

[0023] Figure 3 It is a theoretical diagram of the arc radius measurement tool provided by the embodiment of the utility model using the arc length formula to calculate the arc radius;

[0024] Figure 4 It is a structural schematic diagram of a fixing member provided in an embodiment of the utility model;

[0025] Figure 5 It is an exploded view of the fixing member provided in the embodiment of the utility model.

[0026] In the figure:

[0027] 100. Arc-shaped products;

[0028] 1. First measuring piece; 101. hinge point; 11. First support leg; 111. First assembly hole; 12. Second support leg; 13. Protractor;

[0029] 2. The second measuring piece;

[0030] 3. Fixing member; 31. First rod; 311. First rod body; 3111. Second assembly hole; 312. First threaded connection column; 313. First nut; 32. Second rod; 321. Second rod body; 3211. Third assembly hole; 322. Second threaded connection column; 323. Second nut; 33. Third rod; 331. Third rod body; 332. Third threaded connection column; 333. Third nut; 34. Support block; 341. Socket. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0032] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0034] In the description of this embodiment, the terms "upper", "lower", "right", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0035] The technical solution provided by the utility model is introduced below in conjunction with the accompanying drawings and specific embodiments.

[0036] Combination Figures 1 to 5 As shown, this embodiment provides an arc radius measuring tool, which can measure the radius of arc parts, hoses, tooling and other products.

[0037] Specifically, refer to Figure 1 , Figure 2 As shown, the arc radius measuring tool includes a first measuring piece 1 and a second measuring piece 2. The first measuring piece 1 includes a first leg 11, a second leg 12 and an angle disc 13. The head end of the first leg 11 and the head end of the second leg 12 are hinged at a hinge point 101. The extension lengths of the first leg 11 and the second leg 12 from the head end to the tail end are the same. At least one of the first leg 11 and the second leg 12 is provided with a linear scale on the surface to display the extension length value of the first leg 11 and the second leg 12. The angle disc 13 is provided on the hinge point 101, and an angle scale is provided on the angle disc 13, and the current angle between the first leg 11 and the second leg 12 can be measured. In addition, the second measuring piece 2 is provided on the second leg 12, and the second measuring piece 2 can measure the arc length between the tail end of the first leg 11 and the tail end of the second leg 12.

[0038] Optionally, in this embodiment, the first measuring member 1 is an angle ruler, and the above-mentioned linear scale is provided on the second leg 12. The angle ruler is easy to carry and use, and can also be used on small-sized arc-shaped products 100, with high cost performance.

[0039] Optionally, in this embodiment, the second measuring member 2 is a rolling ruler, such as a digital roller distance meter, a wheel distance meter, a GPS distance meter, etc., which is not limited in this application. The rolling ruler has a simple structure and is more intuitive to operate. When in use, it is only necessary to place the roller in the rolling ruler on the arc surface of the arc-shaped product 100 and roll it to quickly obtain an accurate arc length measurement value, which is conducive to improving the detection efficiency. At the same time, the first measuring member 1 and the second measuring member 2 used in this embodiment are easy to carry and easy to operate.

[0040] In this embodiment, the first leg 11 and the second leg 12 calculate the radius of the arc-shaped product 100 by measuring the arc length of the arc surface concavely arranged on the arc-shaped product 100. Exemplarily, when the arc radius measuring tool is used, the extension length m of the first leg 11 and the second leg 12 is first recorded, and then the tail end of the first leg 11 is abutted and fixed on the arc-shaped product 100. The first leg 11 serves as a fixed leg, and the tail end of the second leg 12 is also abutted on the arc-shaped product 100. The second leg 12 serves as a movable leg and can slide along the arc surface of the arc-shaped product 100. The roller ruler on the second leg 12 can display the distance moved by the second leg 12, that is, the arc length L moved by the second leg 12 on the arc surface, and the angle value a of the protractor 13 at this time is recorded.

[0041] refer to Figure 3 As shown, the arc length L, angle value a and extension length value m are known, and the unknowns are the angle β between the two ends of the arc-shaped product 100 and the radius of the line connecting the center of the circle and the radius R. The angle β, radius R and arc length L satisfy the arc length formula: β×R=L, which is transformed to β=L / R;

[0042] The component principle formula in △ABC and △PBC is:

[0043] n=R×sin(β / 2)=m×sin(a / 2)

[0044] Substituting into the arc length formula and eliminating β:

[0045] R×sin(L / 2R)=m×sin(a / 2)

[0046] After sorting, we can get:

[0047] sin(L / 2R)=m×(sin(a / 2)) / R

[0048] In addition, L / 2R=t, then R=L / 2t, then:

[0049] sint=2m(sin(a / 2))t / L

[0050] By constructing a sine function and a linear equation in the data processing software (such as Excel, SPSS, Python, etc.) on the data processing device, the x value of the intersection point can be obtained. The x value of the intersection point is the value of L / 2R. Since L is known, the R value can be calculated, and the radius of the arc-shaped product 100 can be derived.

[0051] The arc radius measuring tool abuts and fixes the first leg 11 on the arc-shaped product 100, and controls the second leg 12 to slide along the arc surface. When there is a gap between the second leg 12 and the first leg 11, the angle plate 13 can accurately measure the angle between the first leg 11 and the second leg 12, and the second measuring piece 2 can accurately measure the arc length between the tail end of the first leg 11 and the tail end of the second leg 12, and then use the arc length formula to deduce the radius of the arc-shaped product 100. Through the above settings, the arc radius measuring tool can be applied to products of different arc length sizes, and the measurement results are accurate and reliable, while the operation is convenient and simple.

[0052] It should be noted that the second measuring piece 2 can also be communicatively connected to a data processing device, so that the second measuring piece 2 can upload the distance to the data processing device in real time, and then calculate the arc radius through the arc radius derivation formula pre-stored on the data processing device and display it on the electronic screen, thereby further improving the efficiency of measuring the radius of the arc-shaped product 100.

[0053] In other parallel embodiments, the second measuring member 2 can also use a measuring tape, the handle of the measuring tape is set at the tail end of one of the first leg 11 and the second leg 12, and the end of the measuring tape is hooked at the tail end of the other of the first leg 11 and the second leg 12. In this case, when in use, the tail ends of the first leg 11 and the second leg 12 need to be abutted against the convex arc surface of the arc-shaped product 100. When the second leg 12 slides on the arc-shaped product 100, the measuring tape can be closely attached to the arc surface of the arc-shaped product 100, and then the arc length of the arc surface can be intuitively measured by the measuring tape. Therefore, those skilled in the art can choose which type of second measuring member 2 to use according to actual conditions, and this application does not limit this.

[0054] Optionally, the arc radius measuring tool provided in this embodiment also includes a fixing member 3, which is connected to the first support leg 11 and can fix the first support leg 11 on the arc surface of the arc-shaped product 100, thereby avoiding the influence of unstable measurement results caused by manual fixation.

[0055] Specifically, refer to Figure 4As shown, the fixing member 3 includes a first rod 31, a second rod 32 and a third rod 33. The two ends of the first rod 31 are respectively connected to the second rod 32 and the first leg 11, and the end of the second rod 32 away from the first rod 31 is connected to the third rod 33, so that the fixing member 3 is a U-shaped structure, and the third rod 33 and the first rod 31 are located on the arc surface of the arc product 100 on different sides, and the first rod 31 is fitted and abutted against the arc surface of the arc product 100 that is concave inward, and the third rod 33 is fitted and abutted against the arc surface of the arc product 100 that is protruding outward, so that the arc product 100 can be clamped by the third rod 33 and the first rod 31. By inserting the arc radius measuring tool on the arc product 100 in the above manner, not only the structure of the entire arc radius measuring tool is simplified, but also the stability of the connection between the two can be ensured, which helps to improve the measurement efficiency and accuracy.

[0056] More specifically, combined with Figures 4 to 5 As shown, the first rod 31 includes a first rod body 311, a first threaded connection column 312 and a first nut 313. The first rod body 311 is connected to the second rod 32, and the first threaded connection column 312 is protruding from the outer edge of the first rod body 311, and the first nut 313 can be threadedly connected to the first threaded connection column 312. The bottom end of the first support leg 11 is provided with a first assembly hole 111, and the first threaded connection column 312 is passed through the first assembly hole 111 and is threadedly connected to the first nut 313, so that the first support leg 11 is sandwiched between the first nut 313 and the first rod body 311. The fixing member 3 and the first leg 11 are detachably connected by using a threaded connection. On the one hand, it can ensure the connection stability between the first leg 11 and the fixing member 3 and reduce the measurement error. On the other hand, it can be convenient for storage and organization. When in use, the first threaded connection column 312 is directly passed through the first assembly hole 111 and connected to the first nut 313. The surface of the first nut 313 is pressed against the first leg 11, so that the first measuring member 1 can be fixedly set on the arc-shaped product 100.

[0057] It should be noted that, in the present embodiment, the first assembly hole 111 is an arc-shaped hole, so that the fixing member 3 can change the position of the fixing point on the arc-shaped product 100 , thereby better fixing the first measuring member 1 on the arc-shaped product 100 .

[0058] Continue to refer Figure 4 , Figure 5As shown, in this embodiment, the second rod 32 includes a second rod body 321, a second threaded connection column 322 and a second nut 323. The second rod body 312 is connected to the third rod 33, and a second threaded connection column 322 is protruding from the outer edge of the second rod body 321, and the second nut 323 can be threadedly connected to the second threaded connection column 322. In addition, a second assembly hole 3111 is provided on the first rod body 311. After the second threaded connection column 322 passes through the second assembly hole 3111, it is threadedly connected with the second nut 323, and the surface of the second nut 323 fits and abuts on the first rod body 311. At this time, the first rod body 311 can be clamped by the second nut 323 and the second rod body 321, so that the second rod 32 and the first rod 31 are fixedly connected. When disassembling, unscrew the second nut 323 to separate the second rod 32 and the first rod 31. If the second rod 321 needs to be adjusted or replaced, it is only necessary to unscrew the second nut 323 without changing the first rod 311 , thereby improving maintenance efficiency and reducing the scrap rate of the fixing member 3 .

[0059] It should be noted that, in the present embodiment, the second assembly hole 3111 is a waist-shaped hole, and the extension direction of the second assembly hole 3111 is parallel to the width direction of the arc-shaped product 100, so that the third rod 33 can move along the width direction of the arc-shaped product 100, thereby being able to adjust the clamping position of the third rod 33 to stably clamp arc-shaped products 100 of different widths.

[0060] Continue to refer Figure 4 , Figure 5 As shown, in this embodiment, the third rod 33 includes a third rod body 331, a third threaded connection column 332 and a third nut 333, wherein the third rod body 331 is connected to the second rod body 321, and the outer edge of the third rod body 331 is protrudingly provided with a third threaded connection column 332, and the third nut 333 can be threadedly connected to the third threaded connection column 332. In addition, a third assembly hole 3211 is provided on the second rod body 321. Through the above arrangement, the third rod body 331 can be detachably connected to the second rod body 312, which not only facilitates the connection between the second rod body 321 and the third rod body 331, but also facilitates the replacement of the third rod body 331, thereby further improving the use flexibility and use cost of the entire fixing member 3.

[0061] By designing each connection point between the first rod 31 and the first support leg 11, the second rod 32 and the second rod 32, and the third rod 33 and the second rod 32 as a detachable connection, the components can be replaced and adjusted as needed, making the arc radius measuring tool more flexible to use. In addition, during installation, it is only necessary to simply tighten the first nut 313, the second nut 323 and the third nut 333, and they can also be easily loosened during disassembly, so that the operation is simpler and the measurement efficiency is higher.

[0062] It should be noted that, in the present embodiment, the third assembly hole 3211 is also a waist-shaped hole, and the extension direction of the third assembly hole 3211 is parallel to the thickness direction of the arc-shaped product 100, so that the third rod 33 can adjust the clamping position along the thickness direction of the arc-shaped product 100 to clamp arc-shaped products 100 of different thicknesses, thereby further improving the flexibility of use of the fixing member 3.

[0063] It should be supplemented that, in this embodiment, the first rod body 311, the second rod body 321 and the third rod body 331 are the same mold parts, and the three have the same structure and the same material, which helps to save manufacturing costs.

[0064] Optionally, the fixing member 3 provided in this embodiment also includes a support block 34, which is a cylindrical structure and has a socket 341 running through the top. A plurality of support blocks 34 are sleeved on the first rod body 311 and the third rod body 331, so that a support block 34 is sandwiched between the first rod 31 and the arc surface of the arc-shaped product 100, and between the third rod 33 and the arc surface of the arc-shaped product 100, so that the first rod body 311 and the third rod body 331 are supported by the support block 34, thereby improving the force balance of the first rod body 311 and the third rod body 331, thereby enhancing the clamping stability of the fixing member 3.

[0065] It should be noted that the number of support blocks 34 mounted on the first rod 311 and the third rod 331 is the same, so that the forces on the first rod 311 and the third rod 331 are more balanced and stable. For example, in this embodiment, two support blocks 34 are mounted on the first rod 311 and the third rod 331 respectively.

[0066] In the description of this specification, the description of reference terms such as "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0067] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the scope of protection of the present invention. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A circular arc radius measuring tool, used to measure the radius of a circular arc product (100), characterized in that: include: A first measuring piece (1), the first measuring piece (1) comprising a first leg (11), a second leg (12) and an angle disc (13), the head end of the first leg (11) and the head end of the second leg (12) being hinged at a hinge point (101), the tail end of the first leg (11) being able to abut against and be fixed on the arc surface of the arc-shaped product (100), the tail end of the second leg (12) being able to slide around the hinge point (101) and in contact with the arc surface of the arc-shaped product (100), the first leg (11) and the second leg (12) having the same extension length from the head end to the tail end, and at least one of the two being arranged to indicate the extension length, the angle disc (13) being arranged at the hinge point (101), and the angle disc (13) being arranged with an angle scale and being used to measure the current angle between the first leg (11) and the second leg (12); A second measuring piece (2), the second measuring piece (2) is arranged on the second supporting leg (12), and the second measuring piece (2) is capable of measuring the arc length between the tail end of the first supporting leg (11) and the tail end of the second supporting leg (12).

2. The arc radius measuring tool according to claim 1, characterized in that: The second measuring member (2) is a rolling measure; or the second measuring member (2) is a measuring tape, the handle of the measuring tape is arranged at the tail end of one of the first supporting leg (11) and the second supporting leg (12), and the end of the measuring tape is hooked at the tail end of the other of the first supporting leg (11) and the second supporting leg (12).

3. The arc radius measuring tool according to claim 1, characterized in that: The first measuring member (1) is an angle ruler.

4. The arc radius measuring tool according to any one of claims 1 to 3, characterized in that: The arc radius measuring tool further comprises a fixing member (3), wherein the fixing member (3) is connected to the first support leg (11) and is capable of fixing the first support leg (11) on the arc surface of the arc-shaped product (100).

5. The arc radius measuring tool according to claim 4, characterized in that: The fixing member (3) comprises a first rod (31), a second rod (32) and a third rod (33); two ends of the first rod (31) are respectively connected to the second rod (32) and the first support leg (11); one end of the second rod (32) away from the first rod (31) is connected to the third rod (33), so that the fixing member (3) has a U-shaped structure; the third rod (33) and the first rod (31) are located on arc surfaces on different sides of the arc-shaped product (100), so as to cooperate with each other to clamp the arc-shaped product (100).

6. The arc radius measuring tool according to claim 5, characterized in that: The first rod (31) comprises a first rod body (311), a first threaded connection column (312) and a first nut (313); the first rod body (311) is connected to the second rod (32); the first threaded connection column (312) is protruding from the outer edge of the first rod body (311); and the first nut (313) is threadedly connected to the first threaded connection column (312); A first assembly hole (111) is formed at the bottom end of the first support leg (11), and the first threaded connection column (312) is passed through the first assembly hole (111) and is threadedly connected to the first nut (313), so that the first support leg (11) is clamped between the first nut (313) and the first rod body (311).

7. The arc radius measuring tool according to claim 6, characterized in that: The first assembly hole (111) is an arc-shaped hole.

8. The arc radius measuring tool according to claim 6, characterized in that: The second rod (32) comprises a second rod body (321), a second threaded connection column (322) and a second nut (323); the second rod body (321) is connected to the third rod (33); the second threaded connection column (322) is protruding from the outer edge of the second rod body (321); and the second nut (323) is threadedly connected to the second threaded connection column (322); The first rod body (311) is provided with a second assembly hole (3111), and the second threaded connection column (322) is passed through the second assembly hole (3111) and threadedly connected to the second nut (323), so that the first rod body (311) is clamped between the second nut (323) and the second rod body (321).

9. The arc radius measuring tool according to claim 8, characterized in that: The third rod (33) comprises a third rod body (331), a third threaded connection column (332) and a third nut (333); the third rod body (331) is connected to the second rod body (321), and the third threaded connection column (332) is protruding from the outer edge of the third rod body (331); the third nut (333) is threadedly connected to the third threaded connection column (332); A third assembly hole (3211) is formed on the first rod body (311), and the third threaded connection column (332) is passed through the third assembly hole (3211) and threadedly connected to the third nut (333), so that the first rod body (311) is clamped between the third nut (333) and the third rod body (331).

10. The arc radius measuring tool according to claim 5, characterized in that: The fixing member (3) further comprises a support block (34), and the support block (34) is sandwiched between the first rod (31) and the arc surface of the arc-shaped product (100), and between the third rod (33) and the arc surface of the arc-shaped product (100).

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