A test tool for detecting thread deformation of a screw under pre-tightening force

Abstract

The utility model relates to screw quality detection technical field, specifically disclose a kind of test tool for detecting the thread deformation of screw under pre-tightening force state, including counterforce support frame, jack and test screw assembly;Test screw assembly is the detachable butt joint combined structure of at least two screws in axial direction, and at least one exposed thread section on axial butt joint is connected with test nut;Counterforce support frame is used to carry out axial support to test screw assembly;In detection test, test screw assembly is axially tensioned by jack, and the rotatability of test nut on corresponding exposed thread section is detected.The utility model judges the quality of the screw where test nut is located under pre-tightening force state by the rotatability of test nut on corresponding thread section, especially the quality of thread structure, and reliable discrimination screw meeting quality can be applied in corresponding working condition environment.

Description

Technical Field

[0001] This utility model relates to the field of screw quality testing technology, specifically to a test fixture for detecting thread deformation of a screw under preload. Background Technology

[0002] As a type of fastener, the screw is used to detachably connect and fix adjacent mating parts. According to the technical requirements of the working environment, the screw needs to withstand a certain axial preload, which includes the screws widely used in suspension bridge structures.

[0003] In suspension bridge structures, double-ended bolts are widely used, including their arrangement at the saddle groove opening of the cable saddle and at the joint of the cable clamp half.

[0004] In the case of cable clamps, the adjacent halves of the cable clamp are pre-tightened and fixed to the outer periphery of the main cable by multiple screws. This requires axial tensioning of the screws. By axially tensioning the screws, sufficient contact friction is generated between the connected cable clamp halves and the main cable to achieve stable installation on the main cable and to meet the anti-slip capability required by the design technology.

[0005] Based on the aforementioned technical requirements for the anti-slip installation of the cable clamps on the main cable, the locking of the cable clamp's screws on the main cable is achieved through axial tensioning using jacks, rather than simple manual tightening. Therefore, stringent technical requirements are placed on the mechanical properties of the screws, especially the structural deformation of the end thread structure under preload. If the end thread structure deforms under preload, the nut used for locking at this point will be unable to rotate properly, thus preventing tightening / loosening.

[0006] In conclusion, for screws with high technical requirements for stress conditions, quality inspection, especially deformation inspection of the thread structure, is necessary.

[0007] The applicant previously disclosed a tensioning fixture for testing the mechanical properties of a tie rod, as disclosed in Chinese patent literature entitled "A Tensioning Fixture for Testing the Mechanical Properties of a Tie Rod," publication number CN 118032502 A, published on May 14, 2024. This technology discloses a reaction support frame and a jack assembly for axially tensioning the tie rod under test. However, this technology only involves testing the tie rod's mechanical properties such as over-tensioning and static load, and does not involve detecting whether the thread structure of the screw deforms under preload, i.e., it cannot achieve quality testing of the thread structure deformation of the screw under preload. Utility Model Content

[0008] The technical objective of this invention is to provide a test fixture that can effectively detect the deformation of the thread structure of the screw under preload, in light of the special characteristics of the screw under axial preload under working conditions and the special characteristics of the nut on the screw being tightened / loosened by rotation with a threaded structure, thereby effectively detecting the thread quality of the screw under preload.

[0009] The technical objective of this utility model is achieved through the following technical solution: a test fixture for detecting thread deformation of a screw under preload, the test fixture comprising a reaction support frame, a jack and a test screw assembly; The test screw assembly is a detachable joint structure of at least two screws in the axial direction, and a test nut is connected to at least one exposed threaded section at the axial joint. The reaction support frame is used to provide axial support for the test screw assembly, so that one end of the test screw assembly is locked and fixed at the fixed end of the reaction support frame, and the other end of the test screw assembly is connected to the jack and locked and fixed at the tensioning end of the reaction support frame; In the testing, the test screw assembly is axially tensioned using the jack to test the rotatability of the test nut on the corresponding exposed thread section.

[0010] As one of the preferred technical solutions, the test screw assembly is a detachable docking combination structure of the first screw and the second screw in the axial direction; When the test screw assembly is clamped on the reaction support frame, the end of the first screw furthest from the docking part is located outside the tensioning end of the reaction support frame and is connected to the jack; the end of the second screw furthest from the docking part is located outside the fixed end of the reaction support frame and is locked in place.

[0011] Furthermore, the first screw and the second screw of the test screw assembly are axially connected as a whole through a connecting sleeve; The first screw and / or the second screw have an exposed threaded section for connecting a test nut near the connecting sleeve.

[0012] As one of the preferred technical solutions, the reaction support frame has a fixed end plate, a tensioning end plate, and multiple reaction struts; The fixed end plate and the tensioning end plate are arranged at intervals in the tensioning direction to form a tensioning space; Multiple reaction struts are indirectly arranged in the circumferential direction of the tensioning space, connecting the fixed end plate and the tensioning end plate into a whole; The fixed end plate and tensioning end plate within the space enclosed by multiple reaction struts are respectively provided with screw through holes for the test screw assembly to be installed; During the testing, the test nut on the test screw assembly is located within the tensioning space.

[0013] Furthermore, the multiple reaction struts of the reaction support frame are arranged symmetrically on both sides of the tensioning space between the fixed end plate and the tensioning end plate along the tensioning direction.

[0014] Furthermore, on the outer side of the fixed end plate of the reaction support frame, fixed end pads that mate with the corresponding screw holes are arranged; When the test screw assembly is clamped on the reaction support frame, the fixed end of the test screw assembly is locked and fixed on the fixed end pad by the fixed end nut assembly.

[0015] Furthermore, on the outer side of the tensioning end seat plate of the reaction support frame, tensioning end pads that mate with the corresponding screw holes are arranged; When the test screw assembly is clamped on the reaction support frame, the jack connected to the tensioning end of the test screw assembly abuts against the tensioning end pad.

[0016] As one of the preferred technical solutions, the jack has a through-hole structure; When the test screw assembly is clamped on the reaction support frame, the jack is fitted onto the tensioning end of the test screw assembly.

[0017] As one of the preferred technical solutions, the screw component of the test screw assembly is a screw used for locking the cable clamps of a suspension bridge.

[0018] The beneficial technical effects of this utility model are as follows: The above-mentioned technical measures address the unique characteristics of the axial preload on the screw under working conditions, and the unique characteristics of the screw nut's rotational tightening / loosening engagement via a threaded structure. Based on a reaction support frame and a jack, and using a detachable axial assembly of at least two screws and a test screw assembly equipped with a test nut, the test screw assembly is clamped on the reaction support frame and axially tensioned using a jack. This allows for the testing of the rotatability of the test nut on the corresponding threaded section, thereby determining the quality of the screw containing the test nut under preload, especially the quality of the threaded structure. This testing fixture is particularly effective for detecting screw quality, especially for cable clamp screws in suspension bridge structures, reliably identifying screws of acceptable quality for use in cable clamp working conditions. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of one structure of the present utility model.

[0020] Figure 2 for Figure 1 A three-dimensional structural diagram of the structure shown.

[0021] The labels in the diagram have the following meanings: 1—Reaction support frame; 11—Fixed end seat plate; 12—Tensioning end seat plate; 13—Reaction strut; 14—Fixed end pad; 15—Tensioning end pad; 2—Jack; 3—First screw; 31—Tensioning end nut assembly; 4—Second screw; 41—Fixed end nut assembly; 42—Test nut; 43—Exposed thread section; 5—Connecting sleeve. Detailed Implementation

[0022] This utility model relates to the field of screw quality inspection technology, specifically to a test fixture for detecting thread deformation of a screw under preload. The main technical solution of this utility model is described in detail below with reference to several embodiments. Embodiment 1 is illustrated in conjunction with the accompanying drawings. Figure 1 and Figure 2 The technical solution of this utility model is clearly and thoroughly explained; although other embodiments are not shown in separate drawings, their main structures can still be referred to the drawings of Embodiment 1.

[0023] It should be noted that the accompanying drawings of this utility model are schematic, and unnecessary details have been simplified to clarify the technical purpose of this utility model, so as to avoid obscuring the technical solution contributed by this utility model to the prior art. In addition, the expressions such as "about" and "basically" regarding quantity or fit relationship in the following text mean that reasonable assembly errors and processing errors are allowed in the industry, and do not literally describe absolute quantity or fit relationship.

[0024] Example 1 Reference Figure 1 , Figure 2 As shown, this utility model is a test fixture for detecting the deformation of the thread structure of a cable clamp screw under preload, which includes a reaction support frame 1, a jack 2 and a test screw assembly.

[0025] Specifically, the test screw assembly consists of a first screw 3 and a second screw 4, which are detachably joined together axially via a connecting sleeve 5. Both the first screw 3 and the second screw 4 are screws forming the same clamp, thus their structures are identical, and the screws are double-ended, meaning they have threaded sections at both axial ends. The connecting sleeve 5 serves as a transition structure, threadedly connecting to the axial joints of the first screw 3 and the second screw 4, thereby combining the originally independently formed first screw 3 and second screw 4 into a detachable integral structure.

[0026] The aforementioned test screw assembly, being the object of the test, requires the installation of a test nut 42. Therefore, near the connecting sleeve 5, the second screw 4 has an exposed threaded section 43 that connects to the test nut 42 and is exposed outside the connecting sleeve 5. The test nut 42 is threadedly connected to the exposed threaded section 43 of the second screw 4.

[0027] The aforementioned test screw assembly is an integral structure. When it is clamped on the reaction support frame 1, it has a fixed end and a tensioning end. The fixed end is locked and fixed on the reaction support frame 1, and the tensioning end is connected to the jack 2 for axial tensioning.

[0028] The reaction support frame 1 has a fixed end plate 11 and a tensioning end plate 12 arranged at intervals in the tensioning direction to form a tensioning space, and four reaction struts 13 arranged indirectly in the circumferential direction of the tensioning space to connect the fixed end plate 11 and the tensioning end plate 12 into an integral structure. The four reaction struts 13 are arranged symmetrically on both sides of the tensioning space along the tensioning direction, connecting the fixed end plate 11 and the tensioning end plate 12, so that the reaction support frame 1 forms a frame structure with balanced force. In order to meet the clamping and insertion of the above-mentioned test screw assembly, screw through holes for the test screw assembly are respectively opened in the central area of ​​the fixed end plate 11 and the tensioning end plate 12 within the space enclosed by the four reaction struts 13, and preferably the screw through holes on the fixed end plate 11 and the tensioning end plate 12 are axially aligned.

[0029] Based on the technical requirement for the detachable clamping of the test screw assembly on the reaction support frame 1, the screw through holes on the fixed end plate 11 and the tensioning end plate 12 are slightly larger than the outer diameters of the first screw 3 and the second screw 4, allowing the first screw 3 and the second screw 4 to move freely within the corresponding screw through holes. Therefore, to ensure stable clamping of the test screw assembly and protect the reaction support frame 1, a fixed end pad 14 is arranged on the outer side of the fixed end plate 11 to accommodate the corresponding screw through holes and allow the second screw 4 to pass through axially; a tensioning end pad 15 is arranged on the outer side of the tensioning end plate 12 to accommodate the corresponding screw through holes and allow the first screw 3 to pass through axially.

[0030] Jack 2 adopts a through-hole structure - that is, a through-hole jack.

[0031] When the aforementioned test screw assembly is clamped on the aforementioned reaction support frame 1, the first screw 3 of the split part passes axially through the jack 2 and the tensioning end pad 15 and tensioning end seat plate 12 of the reaction support frame 1, and the mating end extends into the tensioning space; the second screw 4 of the split part passes axially through the fixed end pad 14 and fixed end seat plate 11 of the reaction support frame 1, and the mating end extends into the tensioning space. Thus, the mating ends of the first screw 3 and the second screw 4 are both within the tensioning space of the reaction support frame 1 and are axially close together, axially mated by the connecting sleeve 5; at this time, the test nut 42 connected to the exposed threaded section 43 of the second screw 4 is within the tensioning space; the end of the first screw 3 away from the connecting sleeve 5 is outside the tensioning end of the reaction support frame 1 and is connected to the jack 2, and is locked and fixed at the outer end of the jack 2 by the tensioning end nut assembly 31, which abuts against the jack 2, and the jack 2 abuts against the tensioning end pad 15; the end of the second screw 4 away from the connecting sleeve 5 is outside the fixed end of the reaction support frame 1 and is locked and fixed by the fixed end nut assembly 41, which abuts against the fixed end pad 14.

[0032] In the testing, the test screw assembly is axially tensioned using jack 2 until it meets the design preload. At this point, the test nut 42 on the test screw assembly is rotatable. If the test nut 42 can rotate normally on its exposed threaded section 43, it indicates that the thread structure of the second screw 4 under preload has not deformed and meets the quality requirements. If the test nut 42 cannot rotate normally on its exposed threaded section 43, it indicates that the thread structure of the second screw 4 under preload has deformed, does not meet the quality requirements, and cannot be used in cable clamping conditions. Alternatively, it can be used to identify the maximum axial tension load that the first screw can withstand.

[0033] Example 2 The rest of the content of this embodiment is the same as that of embodiment 1, except that: The first screw of the test screw assembly is close to the connecting sleeve and also has an exposed threaded section. An independent test nut is threaded onto the exposed threaded section. That is, the first screw and the second screw that constitute the same test screw assembly are respectively connected to corresponding test nuts. In this way, the first and second screws that make up the same test screw assembly can be inspected simultaneously.

[0034] Example 3 The rest of the content of this embodiment is the same as that of embodiment 1, except that: The test screw assembly is a detachable joint structure of three screws in the axial direction. The axial joint of each pair of adjacent screws is detachably connected by the same connecting sleeve, which requires two connecting sleeves for connection. Based on this, the middle section of the screw is located in the tension space of the reaction support frame, and the outer ends of the screws at both ends form fixed ends and tension ends on the reaction support frame respectively. Furthermore, each of the three screws constituting the test screw assembly has an exposed threaded section, and a corresponding test nut is threaded onto each exposed threaded section.

[0035] Thus, this embodiment can simultaneously perform quality inspection on three screws.

[0036] The above embodiments are only used to illustrate the present invention and are not intended to limit it.

[0037] Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications can still be made to the above embodiments, or equivalent substitutions can be made to some of the technical features. For example, the reaction struts of the reaction support frame can be six or eight struts arranged circumferentially, or the fixed end pad / tensioning end pad can be removed. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the present invention.

Claims

1. A test fixture for detecting thread deformation of a screw under preload, characterized in that: The test fixture includes a reaction support frame (1), a jack (2), and a test screw assembly; The test screw assembly is a detachable joint structure of at least two screws in the axial direction, and a test nut is connected to at least one exposed threaded section at the axial joint. The reaction support frame (1) is used to provide axial support for the test screw assembly, so that one end of the test screw assembly is locked and fixed at the fixed end of the reaction support frame (1), and the other end of the test screw assembly is connected to the jack (2) and locked and fixed at the tensioning end of the reaction support frame (1). In the test, the test screw assembly is axially tensioned by the jack (2) to test the rotatability of the test nut on the corresponding exposed thread section.

2. The test fixture for detecting thread deformation of a screw under preload as described in claim 1, characterized in that: The test screw assembly is a detachable docking structure of the first screw (3) and the second screw (4) in the axial direction; When the test screw assembly is clamped on the reaction support frame (1), the end of the first screw (3) away from the docking part is located outside the tensioning end of the reaction support frame (1) and connected to the jack (2); the end of the second screw (4) away from the docking part is located outside the fixed end of the reaction support frame (1) and is locked and fixed.

3. The test fixture for detecting thread deformation of a screw under preload as described in claim 2, characterized in that: The first screw (3) and the second screw (4) of the test screw assembly are axially joined together as a whole through the connecting sleeve (5); The first screw (3) and / or the second screw (4) have an exposed threaded section for connecting the test nut near the connecting sleeve (5).

4. The test fixture for detecting thread deformation of a screw under preload as described in claim 1 or 2, characterized in that: The reaction support frame (1) has a fixed end plate (11), a tension end plate (12) and multiple reaction struts (13). The fixed end plate (11) and the tensioning end plate (12) are arranged at intervals in the tensioning direction to form a tensioning space; Multiple reaction struts (13) are indirectly arranged in the circumferential direction of the tensioning space to connect the fixed end plate (11) and the tensioning end plate (12) into a whole; The fixed end plate (11) and tension end plate (12) within the space enclosed by multiple reaction struts (13) are respectively provided with screw through holes for the test screw assembly to be installed; During the testing, the test nut on the test screw assembly is located within the tensioning space.

5. The test fixture for detecting thread deformation of a screw under preload as described in claim 4, characterized in that: The multiple reaction struts (13) of the reaction support frame (1) are arranged in a symmetrical manner along the tensioning direction between the fixed end plate (11) and the tensioning end plate (12) on both sides of the tensioning space.

6. The test fixture for detecting thread deformation of a screw under preload as described in claim 4, characterized in that: On the outer side of the fixed end plate (11) of the reaction support frame (1), there are fixed end pads (14) that match the corresponding screw holes. When the test screw assembly is clamped on the reaction support frame (1), the fixed end of the test screw assembly is locked and fixed on the fixed end pad (14) by the fixed end nut assembly.

7. The test fixture for detecting thread deformation of a screw under preload as described in claim 4, characterized in that: On the outer side of the tensioning end plate (12) of the reaction support frame (1), tensioning end pads (15) that match the corresponding screw holes are arranged. When the test screw assembly is clamped on the reaction support frame (1), the jack (2) connected to the tensioning end of the test screw assembly abuts against the tensioning end pad (15).

8. The test fixture for detecting thread deformation of a screw under preload as described in claim 1, 2, or 7, characterized in that: The jack (2) has a through-hole structure; When the test screw assembly is clamped on the reaction support frame (1), the jack (2) is fitted onto the tensioning end of the test screw assembly.

9. The test fixture for detecting thread deformation of a screw under preload as described in claim 1 or 2, characterized in that: The component screw of the test screw assembly is a screw used for locking the cable clamps of a suspension bridge.

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