An anchoring device for fatigue test of uniform cross-section steel wire

Abstract

The present invention relates to the field of fatigue testing devices for steel wire materials, and specifically discloses a fatigue testing anchoring device for steel wires of equal cross-section, including a terminal connecting member, a ball self-locking anchoring member, a dumbbell-shaped ball, and a bolt connector. To ensure the strength and repeated use requirements of the anchoring device, the terminal connecting member and the anchoring member are both processed in one piece. The present invention can firmly clamp the steel wire in the fatigue test of the steel wire of equal cross-section, increase the contact area, and realize the common contact between the steel wire of equal cross-section and the circular arc groove and the ball during the clamping. Moreover, under the support of the cylindrical rubber ring, it can ensure that the stress distribution at the anchoring end of the steel wire of equal cross-section in the fatigue test is uniform, and avoid brittle failure caused by concentrated force at the anchoring end of the steel wire. The present invention has a simple structure and a small size. The size meets the latest fatigue test standard of GB / T3075-2021, and is reusable. It is particularly suitable for anchoring unprocessed steel wires of equal cross-section or other steel cables of equal cross-section.

Description

Technical Field

[0001] The invention relates to the technical field of steel wire material fatigue test devices, in particular to a fatigue test anchoring device for steel wires with uniform cross-sections. Background Art

[0002] Cable-supported bridges are widely favored by bridge designers due to their strong spanning capacity, beautiful form, strong navigation and flood discharge capacity, etc. Among them, the cable system is the main load-bearing component of the cable-supported bridge. Due to the combined effects of environmental erosion, alternating stress and material degradation, the cable is prone to corrosion fatigue damage, becoming the most sensitive component to diseases in the cable-supported bridge. Therefore, effective evaluation of the remaining service life of the cable in a corrosive environment is an important guarantee for the safety and long-term operation and maintenance of the cable-supported bridge. It is necessary to conduct fatigue tests on the steel wire part of the cable. The fatigue test of the steel wire generally adopts the method of clamping the two ends of the steel wire, and then the two clamping ends are brought close to each other and away from each other several times to achieve repeated straightening and rebound of the steel wire, thereby realizing the study of the mechanical properties of the steel wire under different alternating loads. When the repetition process is too much, it is easy to cause a certain left and right movement of the clamping end of the steel wire, which ultimately causes errors in the experimental results. At the same time, in the corrosion fatigue test, because the contact area between the anchor end of the steel wire and the fatigue machine is too small, the local stress at the anchor end of the steel wire is too large and brittle failure occurs, thus affecting the fatigue test results. To ensure uniform stress distribution at the anchor end of the steel wire, the GB / T3075-2021 "Method for Axial Force Control in Fatigue Test of Metallic Materials" specification implemented on March 1, 2022 added the definition and size requirements of "clamping end diameter". Existing equal-section steel wire anchoring technologies include sandblasting both ends of the steel wire or wrapping them with other materials such as tape. During the sandblasting process, it is impossible to ensure uniform sandblasting, so stress concentration still exists. Moreover, the wrapped tape will still be damaged under the extrusion of the fatigue machine, and the strength cannot meet the requirements. Regardless of whether the two ends of the steel wire are sandblasted or wrapped with tape, these two anchoring technologies cannot be reused. Summary of the invention

[0003] In view of the shortcomings existing in the above-mentioned prior art, the present invention proposes a fatigue test anchoring device for uniform-section steel wires, which can firmly clamp the steel wires in the fatigue test of uniform-section steel wires and increase the contact area. During the clamping, the uniform-section steel wires are in contact with the circular arc grooves and the balls. Moreover, with the support of the cylindrical rubber ring, it can ensure that the stress distribution at the anchoring end of the medium-section steel wires in the fatigue test is uniform, thereby avoiding brittle failure caused by concentrated force on the anchoring end of the steel wires.

[0004] The technical solution of the present invention is: a fatigue test anchoring device for a uniform cross-section steel wire, comprising:

[0005] An anchoring member, comprising two half anchors that are buckled together to clamp the steel wire of equal cross-section, each half anchor comprising a circular arc groove that is opened in the buckling surface along the left and right directions and matches the arc surface of the side wall of the steel wire of equal cross-section, and a lug is arranged on both sides of the right end of each half anchor;

[0006] Two pairs of bolt connectors, each pair of bolt connectors comprises bolts and nuts, and when the equal-section steel wire is clamped by the two half-anchors, the lugs corresponding to the two half-anchors are bolted respectively by each pair of bolt connectors;

[0007] The terminal connection component has its right end connected to the anchor component and its left end used to connect to the fatigue machine.

[0008] A two-way ball self-locking structure is provided in the buckling surface of a half anchoring piece of the above-mentioned anchoring component, and the two-way ball self-locking structure includes a pair of ball limiting grooves opened along the direction of the circular arc groove, the groove bottom of each ball limiting groove is set as an inclined surface along the left and right directions, and the inclination directions of the two inclined surfaces are in a left-right symmetrical relationship, and arc-shaped ball shaft guide grooves are opened on the two inner side walls of each ball limiting groove on both sides of the circular arc groove, and a ball is arranged in each ball limiting groove, and the ball is provided with a ball shaft extending from its two end heads, and the two ends of the ball shaft are respectively located in the corresponding ball shaft guide grooves of the ball limiting groove where the ball is located. When the ball is located at the lowest end of the groove bottom of the ball limiting groove where the ball is located, the middle position of the upper surface of the ball is higher than the lowest point of the groove bottom of the corresponding circular arc groove, and when the ball rolls along the corresponding ball shaft guide groove from the lowest point of the groove bottom to the highest point of the groove bottom, the upper surface of the ball gradually rises.

[0009] The above-mentioned ball is a dumbbell-shaped structure that is thin in the middle and thick at both ends and transitions with an arc. The arc curvature of the side wall between the two ends of the ball matches the arc surface curvature of the side wall of the uniform cross-section steel wire. When the two half anchors clamp the uniform cross-section steel wire, the ball is in close contact with the uniform cross-section steel wire; the bottom of the ball limiting groove is set to match the middle height of the arc of the side wall between the two ends of the ball, the lower toward the two inner side walls and the upwardly convex surface transitioning with an arc.

[0010] The ball is sleeved with a cylindrical rubber ring with a thickness of 2-3 mm, and the dynamic friction coefficient μ between the cylindrical rubber ring and the steel wire with a uniform cross-section satisfies μ>0.42.

[0011] After the two half anchors of the above-mentioned anchoring component are buckled together, the side wall of the left end is provided with an external thread structure, and the left end is set as a conical contraction end. The right end of the terminal connecting component is provided with a first internal thread structure matching the external thread structure, and the left end of the first internal thread structure is provided with a conical anchor limiting hole for inserting the conical contraction end. The conical anchor limiting hole is used to make the two half anchors further tightly buckled from the left end.

[0012] The left end of the terminal connection component is provided with a second internal thread structure for threaded connection with the external thread structure of the connection part during fatigue testing of the fatigue machine.

[0013] After the two half anchors of the above-mentioned anchoring member are buckled together, the right end thereof is set as a conical transition end, which is an arc transition end or a straight transition end. When it is a straight transition end, in order to ensure the gradual change requirements of the uniform cross-section steel wire and the total length requirements of the transition end, the angle θ should satisfy: 8°<θ<30°, where θ is the angle between the generatrix of the conical transition end and the center line of the uniform cross-section steel wire.

[0014] Use a sandblasting machine with 0.1 refined quartz sand to evenly blast the arc groove to increase the friction between the arc groove and the steel wire with equal cross-section.

[0015] A nut positioning hole is provided on the lug of one of the half anchors to fix the nut when the bolt is turned for tightening, wherein the hexagonal diagonal distance s' of the nut positioning hole shall satisfy: s+0.1mm<s'<1.06s, wherein s is the hexagonal diagonal distance of the nut.

[0016] When the anchoring member is in a clamping state, the whole is a columnar structure. The anchoring member is processed in an integrated manner. The distance between the center line of the anchoring member and the symmetric surface is respectively The two planes are cut to obtain two half anchors, where l is the spacing of the contraction joints. The spacing l of the contraction joints should satisfy: d is the diameter of the uniform cross-section steel wire.

[0017] Beneficial effects of the present invention: The present invention provides an anchoring device for fatigue test of equal-section steel wire. To ensure the strength of the anchoring device and the requirements of repeated use, the anchoring component is processed in one piece, and the lug 9 is pre-set with a bolt hole 20. The present invention can firmly clamp the equal-section steel wire. The bidirectional ball self-locking structure provided inside the anchoring device can play a clamping and tightening role when the equal-section steel wire is in a tensile state and a clamping and tightening role when the equal-section steel wire is in a compression state test under the cooperation between the ball, the ball limiting groove and the equal-section steel wire. When the equal-section steel wire is subjected to tensile and compression tests, it plays a very strong tightening role to avoid the steel wire slipping and causing the test failure. The ball 12 of the present invention can ensure that the equal-section steel wire 14 has a self-locking effect when there is a tendency of unidirectional movement, effectively limiting the axial displacement of the equal-section steel wire 14. By using two completely identical balls 12 and two completely left-right symmetrical ball limiting grooves 8, the equal-section steel wire 14 can be reliably anchored under fatigue load. In addition, both sides of the anchoring member are provided with double-ear symmetrical lugs 9, which can effectively ensure that during the installation process, the positions of the anchoring member, the dumbbell-shaped ball 12 and the uniform cross-section steel wire 14 are relatively stable, thereby improving the friction between the anchoring member and the uniform cross-section steel wire 14. The present invention uses a sandblasting machine equipped with 0.1mm refined quartz sand to evenly sandblast the circular arc groove of the anchoring member, which can further increase the friction between the circular arc groove and the steel wire. The present invention can ensure uniform stress distribution on one side of the medium cross-section steel wire 14 in the fatigue test, and avoid brittle failure caused by concentrated force on the uniform cross-section steel wire. After installing the anchoring device, at the arc transition end, the cross-sectional size of the steel wire and the anchoring device changes slowly and evenly, meeting the requirement of gradual change of the cross-sectional area of ​​the steel wire. The present invention has a simple structure and small size. The dimensions conform to the latest fatigue test standard GB / T3075-2021 and are reusable. It is particularly suitable for anchoring unprocessed uniform-section steel wires or other uniform-section steel cables. It can avoid brittle failure caused by concentrated force at the anchoring end of the steel wire and the problem of affecting the test results due to the clamping end diameter not meeting the specification requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the overall arrangement diagram of the fatigue test anchoring device for uniform cross-section steel wires of the present invention;

[0019] Figure 2A It is a schematic diagram of the explosion structure of the anchoring device for fatigue test of uniform cross-section steel wire of the present invention;

[0020] Figure 2B It is a schematic diagram of the internal cross-sectional structure of the terminal connection component of the fatigue test anchoring device for uniform cross-section steel wires of the present invention and the connection correspondence between the half anchors;

[0021] Figure 3It is a schematic diagram of dumbbell-shaped ball installation of the anchor device for fatigue test of uniform cross-section steel wire of the present invention;

[0022] Figure 4 It is a schematic diagram of the relationship between the dumbbell-shaped ball and the cylindrical rubber ring of the uniform cross-section steel wire fatigue test anchoring device of the present invention, which are assembled into a dumbbell-shaped ball with a cylindrical rubber ring;

[0023] Figure 5 It is a schematic diagram of the outer surfaces and the buckling surfaces of two half anchors of the fatigue test anchor device for steel wires of equal cross-section according to the present invention. DETAILED DESCRIPTION

[0024] Combine the following Figure 1-Figure 5 , a specific embodiment of the present invention is described in detail, but it should be understood that the protection scope of the present invention is not limited by the specific embodiment.

[0025] In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the technical solution of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. It is understood by those skilled in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of ordinary technicians in the field to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless defined as here.

[0026] See Figure 2. Figure 3 as well as Figure 5 The present invention provides a fatigue test anchoring device for a uniform cross-section steel wire, comprising: an anchoring member, two pairs of bolt connectors, and a terminal connection member 1 (such as the attached Figure 2AThe bottle-shaped part in the figure) wherein the anchoring member comprises two half anchors 5 which are buckled together to clamp the uniform cross-section steel wire 14, each half anchor 5 comprises an arc groove 16 which is opened in the buckling surface along the left and right direction and matches the arc surface of the side wall of the uniform cross-section steel wire, and a lug 9 is arranged on both sides of the right end of each half anchor 5. Each pair of bolt connectors comprises a bolt 13 and a nut 15, and when the uniform cross-section steel wire 14 is clamped by the two half anchors 5, the lugs 9 corresponding to the two half anchors 5 are bolted respectively by each pair of bolt connectors. The right end of the terminal connection member 1 is connected to the anchoring member, and the left end is used to connect to the fatigue machine.

[0027] Furthermore, a bidirectional ball self-locking structure is provided in the buckling surface of one half anchor 5 of the anchoring member, and the bidirectional ball self-locking structure includes a pair of ball limiting grooves 8 opened along the arc groove 16, and the bottom of each ball limiting groove 8 is set as an inclined surface along the left and right directions, and the inclination directions of the two inclined surfaces are in a left-right symmetrical relationship, and arc-shaped ball shaft guide grooves 18 are opened on the two inner side walls of each ball limiting groove 8 on both sides of the arc groove 16, and a ball is placed in each ball limiting groove 8. 12, the ball 12 is provided with a ball shaft extending from its two ends, and the two ends of the ball shaft are respectively located in the corresponding ball shaft guide groove 18 of the ball limiting groove 8 where each ball 12 is located. When the ball 12 is located at the lowest end of the groove bottom of the ball limiting groove 8 where it is located, the middle position of the upper surface of the ball 12 is higher than the lowest point of the groove bottom of the corresponding arc groove 16. When the ball 12 rolls along the corresponding ball shaft guide groove 18 from the lowest point of the groove bottom to the highest point of the groove bottom, the upper surface of the ball 12 gradually rises. Figure 3 As shown in the accompanying drawings of a specific embodiment, the two ball limiting grooves 8 are symmetrical on the left and right, and the opposite ends of the two ball limiting grooves 8 are set as the lowest points of the inclined surface of the groove bottom. To facilitate the installation or replacement of the ball 12, one end of the ball shaft guide groove 18 is connected to the snap-fit ​​surface of the semi-anchor 5 where it is located. To enhance the self-locking effect of the contact between the ball 12 and the cross-sectional steel wire 14, the arc-shaped ball guide groove is relatively gentle near the bottom of the ball limiting groove 8, and this arc section is basically parallel to the inclined surface of the groove bottom of the ball limiting groove 8.

[0028] Furthermore, in order to increase the contact area between the ball 12 and the uniform cross-section steel wire 14, the ball 12 is set to a dumbbell-shaped structure with a thin middle and thick ends and an arc transition. The arc curvature of the side wall between the two ends of the ball 12 matches the arc curvature of the side wall of the uniform cross-section steel wire. When the two half anchors 5 clamp the uniform cross-section steel wire 14, the ball 12 is in close contact with the uniform cross-section steel wire 14. In order to ensure that the ball 12 is in close contact with the uniform cross-section steel wire 14, the entire ball body diameter of the ball 12 can be designed to be slightly larger, so that the gap between the two ends of the ball 12 is The middle part of the arc of the side wall is higher than the lowest point of the bottom of the corresponding arc groove 16 (the height range is between 0.1-0.3mm); in order to increase the contact area between the dumbbell-shaped ball 12 and the bottom surface of the ball limiting groove 8, so as to form better upward support for the ball 12, make the ball less likely to deform and form a tight fit with the uniform cross-section steel wire 14, the bottom of the ball limiting groove 8 is set to match the middle height of the arc of the side wall between the two ends of the ball 12, lower toward the two inner side walls and an upwardly convex curved surface with an arc transition. After the clamping and anchoring of the equal-section steel wire is completed in the present invention, when the equal-section steel wire is pulled, under the joint restriction of the arc groove 16 and the ball limiting groove 8, the ball 12 close to the terminal connecting component 1 produces a self-locking effect under the pulling of the equal-section steel wire; and when the equal-section steel wire is compressed, the ball 12 far away from the terminal connecting component 1 produces a self-locking effect under the push of the equal-section steel wire, effectively limiting the displacement of the equal-section steel wire in the left and right directions under the action of fatigue load.

[0029] Further, see Figure 4 The ball 12 is sleeved with a 2-3mm thick cylindrical rubber ring 19. The dynamic friction coefficient μ between the cylindrical rubber ring 19 and the uniform cross-section steel wire 14 satisfies μ>0.42, so as to ensure that the ball 12 can be driven to roll when the uniform cross-section steel wire 14 has an axial micro-movement tendency, thereby forming a self-locking effect on the uniform cross-section steel wire. In addition, with the support of the cylindrical rubber ring 19, it can also ensure that the stress distribution at the anchor end of the medium cross-section steel wire in the fatigue test is uniform, avoiding the brittle failure caused by the concentrated force at the anchor end of the steel wire. The cylindrical rubber ring 19 can be made of chloroprene rubber with high tensile strength and high friction coefficient. The cylindrical rubber ring 19 is a consumable, low-cost and easy to replace.

[0030] Furthermore, after the two half-anchors 5 of the anchoring member are buckled together, the side wall of the left end is provided with an external thread structure 7, and the left end is set as a conical contraction end 6. The right end of the terminal connection member 1 is provided with a first internal thread structure 4 matching the external thread structure 7, and the left end of the first internal thread structure is provided with a conical anchor limiting hole 3 for inserting the conical contraction end 6. The conical anchor limiting hole 3 is used to make the two half-anchors 5 further tightly buckled from the left end.

[0031] Furthermore, the left end of the terminal connection member 1 is provided with a second internal thread structure 2 for threaded connection with the external thread of the connection part during fatigue testing of the fatigue machine (see Figure 2B ).

[0032] Furthermore, after the two half anchors 5 of the anchoring member are buckled together, the right end thereof is set as a conical transition end 10, and the conical transition end 10 is an arc transition end. To simplify the processing technology, the conical transition end 10 can also be designed as a straight transition end. When it is a straight transition end, in order to ensure the gradual change requirements of the uniform cross-section steel wire 14 and the total length requirements of the transition end, the angle θ should satisfy: 8°<θ<30°, θ is the angle between the generatrix of the conical transition end 10 and the center line of the uniform cross-section steel wire 14.

[0033] Furthermore, the arc groove 16 is evenly sandblasted using a sandblasting machine loaded with 0.1 refined quartz sand to increase the friction between the arc groove 16 and the uniform cross-section steel wire 14 .

[0034] Furthermore, in order to avoid the contact surface between the nut 15 and the lug 9 becoming smooth due to repeated use, and the nut 15 and the lug 9 being prone to relative rotation, which affects the stress condition of the bolt in the pre-anchoring stage, a nut positioning hole 11 is provided on the lug 9 of one of the semi-anchors 5, so as to fix the nut 15 when the bolt 13 is tightened, wherein the hexagonal diagonal distance s' of the nut positioning hole 11 shall satisfy: s+0.1mm<s'<1.06s, wherein s is the hexagonal diagonal distance of the nut 15.

[0035] Furthermore, when the anchoring member is in a clamping state, the entire structure is a columnar structure. The anchoring member is processed in an integrated manner, and the distance between the center line of the anchoring member and the symmetric surface is respectively The two planes are cut to obtain two half anchors 5, where l is the spacing of the contraction joints, and the spacing l of the contraction joints should satisfy: d is the diameter of the sample of uniform cross-section steel wire 14.

[0036] The anchoring method of the cross-section steel wire fatigue test anchoring device of the present invention comprises the following steps:

[0037] (1) Turn the terminal connection member 1 clockwise to connect the fatigue machine connection end of the terminal connection member 1 to the loading end of the fatigue testing machine.

[0038] (2) Place the dumbbell-shaped ball 12 into the ball limiting groove 8 through the arc-shaped ball shaft guide groove 18. Align the two half anchors 5 holding the uniform cross-section steel wire 14, and place the nut 15 flat in the nut positioning hole 11. At the same time, pass the hexagonal bolt 13 through the bolt hole 20 reserved in the lug 9, and use a hexagonal wrench to tighten the bolt 13 through the hexagonal slot of the bolt, so that the bolt 13 and the nut 15 are in an untightened state. Depending on the stiffness of the uniform cross-section steel wire 14 used in the test, different sizes of dumbbell-shaped balls 12 are selected. If the test uses a high-strength uniform cross-section steel wire, a relatively small dumbbell-shaped ball 12 should be selected.

[0039] (3) The anchoring member is threadedly connected to the first internal thread structure 4 of the terminal connection member 1 in a clockwise manner until the conical contraction end 6 is locked in the conical anchor limit hole 3, and ensure that the uniform cross-sectional steel wire 14 cannot be twisted by hand. Finally, tighten the bolt 13 with an inner hexagonal wrench to complete the anchoring of one side of the uniform cross-sectional steel wire; repeat the above anchoring steps to complete the anchoring of the other end of the uniform cross-sectional steel wire 14 with the other end of the cross-sectional steel wire fatigue test anchoring device (see Figure 1 As shown), the anchoring of both ends of the uniform cross-section steel wire 14 is achieved.

[0040] The present invention takes the anchoring of φ5mm uniform cross-section steel wire 14 as an example. The anchoring member included in the present invention uses φ22mm×110mm rough material and is placed on the GSK980TB3 CNC system lathe for integrated processing. The excess part of the outer surface is removed by programming the external cylindrical turning tool of the CNC system lathe, and the inner anchoring end is obtained by drilling a hole in the center of the rough material with a 4mm center drill. Then, the two planes 0.5mm away from the symmetry plane are cut using electric spark wire cutting technology. Finally, the inner anchoring end is evenly sandblasted using a sandblasting machine. The diameter D of the anchoring member and the diameter d of the uniform cross-section steel wire should satisfy D≥2d+2mm. The middle part of the anchoring member can also be re-anchored using a φ12mm throat clamp. The terminal connection member and the anchoring member of the present invention are both processed in an integrated manner. The fatigue test anchoring device of the present invention has a simple structure and a small size, and the size meets the latest fatigue test standard GB / T3075-2021. It is suitable for anchoring unprocessed uniform cross-section steel wires or other uniform cross-section steel cables. It can avoid brittle failure caused by concentrated force at the anchoring end of the steel wire and the diameter of the clamping end not meeting the requirements of the specification, which will affect the test results.

[0041] In summary, the present invention can not only clamp the steel wire securely in the fatigue test by means of the self-locking effect of the ball, but also increase the contact area, realize the common contact between the equal-section steel wire, the arc groove and the ball during clamping, and ensure the uniform stress distribution of the anchoring end of the equal-section steel wire in the fatigue test under the clamping of the cylindrical rubber ring, so as to avoid the brittle failure caused by the concentrated force on the anchoring end of the steel wire. The present invention can clamp the equal-section steel wire securely, and the bidirectional ball self-locking structure provided inside it can play the role of clamping and tightening the equal-section steel wire when it is in the tensile state and the role of clamping and tightening the equal-section steel wire when it is in the compression state test under the cooperation between the ball, the ball limiting groove and the equal-section steel wire. When the equal-section steel wire is subjected to the tensile and compression tests, it plays an extremely strong tightening role to avoid the steel wire slipping and causing the test failure. The ball bearing 12 of the present invention can ensure that the uniform cross-section steel wire 14 produces a self-locking effect when there is a tendency of unidirectional movement, effectively limiting the axial displacement of the uniform cross-section steel wire 14. By adopting two completely identical ball bearings 12 and two completely left-right axially symmetrical ball bearing limit grooves 8, the uniform cross-section steel wire 14 can be reliably anchored under fatigue load. In addition, both sides of the anchoring member are provided with double-ear symmetrical lugs 9, which can effectively ensure that the positions of the anchoring member, the dumbbell-shaped ball bearing 12 and the uniform cross-section steel wire 14 are relatively stable during the installation process, thereby improving the friction between the anchoring member and the uniform cross-section steel wire 14. The present invention uses a sandblasting machine equipped with 0.1mm refined quartz sand to uniformly sandblast the circular arc groove of the anchoring member, which can further increase the friction between the circular arc groove and the steel wire. The present invention can ensure that the stress distribution on one side of the medium cross-section steel wire 14 in the fatigue test is uniform, and avoid brittle failure caused by concentrated force on the uniform cross-section steel wire. After installing the anchor device, at the arc transition end, the cross-sectional size of the steel wire and the anchor device changes slowly and evenly, meeting the requirements of the gradual change of the cross-sectional size of the steel wire. The invention has a simple structure and small size, and the size meets the latest fatigue test standard GB / T3075-2021, and can be reused. It is particularly suitable for anchoring unprocessed uniform cross-sectional steel wires or other uniform cross-sectional steel cables, which can avoid the problem of brittle failure caused by concentrated force at the anchor end of the steel wire and the problem of affecting the test results caused by the clamping end diameter not meeting the specification requirements.

[0042] The above disclosures are only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A fatigue test anchoring device for uniform cross-section steel wire, characterized in that: include: An anchoring member comprises two half anchors (5) which are buckled together to clamp a steel wire (14) of uniform cross-section, each half anchor (5) comprises a circular arc groove (16) which is arranged in the buckling surface thereof along the left-right direction and matches the arc surface of the side wall of the steel wire of uniform cross-section, and a lug (9) is arranged on both sides of the right end of each half anchor (5); Two pairs of bolt connectors, each pair of bolt connectors comprises a bolt (13) and a nut (15), and when the two half-anchors (5) clamp the steel wire (14) of equal cross-section, the lugs (9) corresponding to the two half-anchors (5) are bolted respectively through each pair of bolt connectors; A terminal connection member (1), the right end of which is connected to the anchor member, and the left end of which is used to be connected to the fatigue machine; A bidirectional ball self-locking structure is provided in the buckling surface of a half anchoring member (5) of the anchoring member, and the bidirectional ball self-locking structure comprises a pair of ball limiting grooves (8) arranged along the arc groove (16), the groove bottom of each ball limiting groove (8) is arranged as an inclined surface in the left-right direction, and the inclination directions of the two inclined surfaces are in a left-right symmetrical relationship, and arc-shaped ball shaft guide grooves (18) are arranged on the two inner side walls of each ball limiting groove (8) located on both sides of the arc groove (16), and a ball (12) is arranged in each ball limiting groove (8). The ball (12) is provided with a ball shaft extending from its two ends, and the two ends of the ball shaft are respectively located in the corresponding ball shaft guide groove (18) of the ball limiting groove (8) where each ball (12) is located. When the ball (12) is located at the lowest end of the groove bottom of the ball limiting groove (8) where it is located, the middle position of the upper surface of the ball (12) is higher than the lowest point of the groove bottom of the corresponding arc groove (16). When the ball (12) rolls along the corresponding ball shaft guide groove (18) from the lowest point of the groove bottom to the highest point of the groove bottom, the upper surface of the ball (12) gradually rises.

2. A uniform cross-section steel wire fatigue test anchoring device as claimed in claim 1, characterized in that: The ball (12) is a dumbbell-shaped structure that is thin in the middle and thick at both ends and transitions with an arc. The arc curvature of the side wall between the two ends of the ball (12) matches the arc surface curvature of the side wall of the uniform cross-section steel wire (14). When the two half anchors (5) clamp the uniform cross-section steel wire (14), the ball (12) is in close contact with the uniform cross-section steel wire (14); the groove bottom of the ball limiting groove (8) is set to match the middle height of the arc of the side wall between the two ends of the ball (12), the lower surface towards the two inner side walls and transitions with an arc, and is an upwardly convex curved surface.

3. A uniform cross-section steel wire fatigue test anchoring device as claimed in claim 1 or 2, characterized in that: The ball (12) is sleeved with a cylindrical rubber ring (19) with a thickness of 2-3 mm, and the dynamic friction coefficient μ between the cylindrical rubber ring (19) and the uniform cross-section steel wire (14) satisfies μ>0.

42.

4. A uniform cross-section steel wire fatigue test anchoring device as claimed in any one of claims 1 to 2, characterized in that: After the two half anchors (5) of the anchoring member are buckled together, the side wall of the left end is provided with an external thread structure (7), and the left end is set as a conical contraction end (6). The right end of the terminal connection member (1) is provided with a first internal thread structure (4) matching the external thread structure (7), and the left end of the first internal thread structure is provided with a conical anchor limiting hole (3) for inserting the conical contraction end (6). The conical anchor limiting hole (3) is used to make the two half anchors (5) further tightly buckled from the left end.

5. A uniform cross-section steel wire fatigue test anchoring device as claimed in any one of claims 4, characterized in that: The left end of the terminal connection component (1) is provided with a second internal thread structure (2) for threaded connection with the external thread of the connection part during fatigue testing of the fatigue machine.

6. A uniform cross-section steel wire fatigue test anchoring device as claimed in any one of claims 1 to 2, characterized in that: After the two half anchors (5) of the anchoring member are buckled together, the right end thereof is set as a conical transition end (10), and the conical transition end (10) is a circular arc transition end or a straight transition end. When it is a straight transition end, in order to ensure the gradual change requirements of the uniform cross-section steel wire (14) and the total length requirements of the transition end, the angle θ should meet the following requirements: 8°<θ<30°, and θ is the angle between the generatrix of the conical transition end (10) and the center line of the uniform cross-section steel wire (14).

7. The uniform cross-section steel wire fatigue test anchoring device according to claim 1, characterized in that: The circular arc groove (16) is evenly sandblasted using a sandblasting machine loaded with 0.1 refined quartz sand to increase the friction between the circular arc groove (16) and the uniform cross-section steel wire (14).

8. The uniform cross-section steel wire fatigue test anchoring device according to claim 1, characterized in that: A nut positioning hole (11) is provided on the lug (9) of one of the half anchors (5) for fixing the nut (15) when the bolt (13) is tightened, wherein the hexagonal diagonal distance s′ of the nut positioning hole (11) should satisfy: s+0.1mm<s′<1.06s, wherein s is the hexagonal diagonal distance of the nut (15).

9. The uniform cross-section steel wire fatigue test anchoring device according to claim 1, characterized in that: When the anchoring member is in a clamping state, the whole is a columnar structure. The anchoring member is processed in an integrated manner. The electric spark wire cutting process is used to cut the distance between the center line of the anchoring member and the symmetric surface. The two planes are cut to obtain two half anchors (5), where l is the spacing of the contraction joints. The spacing l of the contraction joints should satisfy: , d is the diameter of the uniform cross-section steel wire (14).

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