Connecting piece and supporting anchor rod

Abstract

The utility model discloses a connecting piece which comprises a columnar body, the end portion of the columnar body is provided with a first thread used for being aligned and meshed with a piece to be connected, the first thread is a taper thread, and the taper of the taper thread is determined by the size and the material attribute of the piece to be connected. The utility model has the beneficial effects that: when a to-be-connected piece is connected with the columnar body, firstly, the thread contact surface is gradually compressed to realize high-precision centering and uniform stress, and secondly, the conical structure forms a self-locking structure through screwing fit, so that the pre-tightening force between threads is enhanced, and the anti-drawing performance and the anti-torsion capability are obviously improved.

Description

Technical Field

[0001] This utility model relates to the field of geotechnical engineering anchoring technology, and in particular to a connector and a support anchor rod. Background Technology

[0002] Due to the influence of the complex geological environment in the deep, the mining environment is becoming more variable and complex, the integrity and stability of the surrounding rock are poor, the roadway support is difficult, and the problems of large deformation of soft rock under high stress and impact disasters are becoming increasingly prominent. The weaknesses of traditional anchor bolt support and the problem of anchor failure are beginning to emerge, making it difficult to ensure the safe mining of kilometer-deep roadways.

[0003] Chinese patent CN2087690U discloses a threaded anchor bolt, which consists of an anchor head, a rod body, an anchor disc, and a nut; the anchor head has an internal threaded hole at its center that mates with the rod body, and external threads on the outer edge of the anchor head, which are connected by the threads.

[0004] Clearly, although this type of threaded anchor bolt achieves the connection between the anchor head and the anchor bolt, the length of the anchor bolt is fixed. Under the same conditions, the longer the anchor bolt, the larger its influence range and the more significant reinforcement effect on loosened surrounding rock. However, due to constraints such as tunnel construction space and construction process, the length of commonly used anchor bolts in coal mines is generally 2.4-2.5m, with a maximum of no more than 3.0m. Therefore, how to increase the length of the anchor bolt while ensuring the stability of the connection between them and avoiding deviation and failure is a problem that urgently needs to be solved by those skilled in the art.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this utility model and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Utility Model Content

[0006] The technical problem to be solved by this utility model is to obtain an anchor connection method that combines high load-bearing capacity, anti-skewness characteristics and long-term stability to meet the stringent requirements in engineering practice.

[0007] This utility model solves the above-mentioned technical problems through the following technical means:

[0008] This utility model claims protection for a connector, including a columnar body, the end of which is provided with a first thread for aligning and engaging with a component to be connected. The first thread is a tapered thread, wherein the taper of the tapered thread is determined by the size and material properties of the component to be connected.

[0009] Preferably, the taper satisfies the following formula:

[0010]

[0011] Where θ is the taper, k is the correction factor, and σ a denoted as denoted as the allowable stress of the parts to be connected, d as the diameter of the parts to be connected, E as the elastic modulus of the material of the parts to be connected, and μ as the friction coefficient of the tapered thread contact surface.

[0012] Preferably, the first thread is an internal thread or an external thread. When the first thread is an internal thread, the cylindrical body portion of the first thread is cylindrical.

[0013] When the first thread is an external thread, the cylindrical body portion that provides the first thread is shaft-shaped.

[0014] Preferably, the tapered thread profile is triangular.

[0015] Preferably, the columnar body is a 50CrV high-strength alloy steel sleeve.

[0016] Preferably, the outer wall of the columnar body is provided with anti-slip components.

[0017] This utility model also claims protection for a support anchor bolt, which uses a connector including a connecting sleeve and at least two anchor bolt bodies. The anchor bolt bodies are arranged coaxially, and their adjacent ends are provided with a second thread adapted to the first thread. The second thread is aligned and engaged with the first thread at the corresponding end of the connecting sleeve.

[0018] Preferably, the anchor bolt body is an MG type anchor bolt.

[0019] Preferably, the surfaces of the first and second threads are covered with an anti-corrosion coating.

[0020] Preferably, a sealing element is provided between the anchor bolt body and the connecting sleeve.

[0021] The advantages of this utility model are:

[0022] 1. By setting a tapered thread at the end of the columnar body, when connecting the part to be connected to the columnar body, during the thread engagement process, firstly, the thread contact surface is gradually pressed together to achieve high-precision centering and uniform force distribution. Secondly, the tapered structure forms a self-locking structure through tightening, which enhances the preload between the threads, significantly improves the pull-out resistance and torsional resistance, and reduces the risk of installation misalignment.

[0023] At the same time, this application also concludes that the taper of the thread plays a crucial role in achieving the optimal connection between the cylindrical body and the part to be connected. Therefore, further research shows that the size of the taper is determined by the size and material properties of the part to be connected, which means that the required connection effect can be achieved by changing the size and material properties according to actual working needs, making it highly applicable.

[0024] Second, by further deriving the formula for calculating the taper, the desired taper can be accurately calculated, and the connection effect between the columnar body and the part to be connected can be predicted. The result is accurate, which not only reduces the usage cost brought about by experiments, but also reduces the reliance of skilled workers on technology and lowers labor costs.

[0025] Third, the first thread is either an internal thread or an external thread, which includes three technical solutions: Technical solution one, both ends of the cylindrical body are provided with internal threads; Technical solution two, both ends of the cylindrical body are provided with external threads; Technical solution three, one end of the cylindrical body is provided with an internal thread and the other end is provided with an external thread. In actual production, the three technical solutions can be analyzed from three aspects: stress characteristics, cost, and processing, installation and maintenance, in order to determine the applicable scenarios.

[0026] In terms of stress characteristics, when the first thread is an internal thread, the stress is concentrated at the meshing point between the inner wall of the cylindrical body and the part to be connected, resulting in higher tensile strength, but the cylindrical body is subjected to greater shear force.

[0027] From the perspective of cost and processing, the cost of internal thread processing, such as tapping, is relatively low for cylindrical bodies.

[0028] In terms of installation and maintenance, when the first thread is an internal thread, the cylindrical body can be installed directly by tightening, which is relatively simple. However, when the first thread is an external thread, the cylindrical body needs to be screwed into the part to be connected, which requires higher precision in the thread.

[0029] It can be selected according to actual work needs and work environment, and has high applicability and wide range.

[0030] IV. The tapered thread profile is triangular, which has the following three advantages compared to the straight thread in the existing technology: First, the tapered thread and the triangular profile have a synergistic effect. When the tapered thread is tightened, the tapered angle gradually compresses, generating radial pressure. The sharp tooth tip and root of the triangular profile can more effectively embed into the mating surface and fill the tiny gaps, thus providing good sealing performance and further optimizing the connection stability. Second, compared with trapezoidal or rectangular threads, the smaller tooth flank angle of the triangular profile increases the frictional resistance between the thread pairs. Combined with the wedging effect of the tapered angle, it can effectively resist loosening caused by axial loads. Third, although the contact surface of the triangular profile is smaller than that of the trapezoidal thread, its symmetrical structure can disperse axial force in the tapered fit, reduce stress concentration, and extend the service life of the connected parts.

[0031] 5. The cylindrical body is made of 50CrV high-strength alloy steel sleeve, which has high tensile strength to ensure that the threads will not be damaged under high load.

[0032] 6. The outer wall of the columnar body is equipped with anti-slip parts, which can be anti-slip sleeves or anti-slip knurling, to facilitate personnel tightening operations.

[0033] VII. This utility model also claims protection for a support anchor bolt, wherein an isolation layer is provided on the threads of the anchor bolt body and the columnar body that mesh, and the anti-corrosion coating can be galvanized or coated with an anti-corrosion coating to improve its anti-corrosion performance.

[0034] 8. A sealing element is installed between the anchor bolt body and the connecting sleeve. The sealing element can be a sealing ring or a sealing gasket to enhance the sealing performance of the connection and prevent moisture or corrosive substances from entering the support anchor bolt in engineering practice. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the connector and the component to be connected in the first embodiment of the present utility model.

[0036] Figure 2 This is a schematic diagram of the connector and the component to be connected in the second technical solution of Embodiment 1 of this utility model;

[0037] Figure 3 This is a schematic diagram of the connector and the component to be connected in technical solution three of embodiment one of this utility model;

[0038] Figure 4 This is a displacement-test force curve of different taper threads in a tensile test according to Embodiment 3 of this utility model.

[0039] 10. Columnar body; 100. First thread;

[0040] 20. Anchor bolt body; 200. Second thread. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below in conjunction with the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0042] Example 1

[0043] See Figures 1 to 3 This embodiment requires protection of a connector, including a columnar body 10. The columnar body 10 is a 50CrV high-strength alloy steel sleeve with high tensile strength to ensure that the threads will not be damaged under high load. The outer wall of the columnar body 10 is provided with anti-slip parts, which can be anti-slip sleeves or anti-slip knurling, to facilitate personnel tightening operations.

[0044] Furthermore, the end of the columnar body 10 is provided with a first thread 100 for aligning and engaging the parts to be connected. The first thread 100 is an internal thread or an external thread. When the first thread 100 is an internal thread, the part of the columnar body 10 with the first thread 100 is cylindrical; when the first thread 100 is an external thread, the part of the columnar body 10 with the first thread 100 is shaft-shaped.

[0045] It is worth mentioning that the first thread 100 can be either an internal or external thread, encompassing three technical solutions. (See attached document.) Figure 1 Technical Solution 1: The columnar body 10 is cylindrical, with internal threads on the inner walls at both ends; see reference. Figure 2 Technical solution two: the columnar body 10 is shaft-shaped, and both outer walls of the shaft are provided with external threads; see reference. Figure 3 Technical Solution 3: The columnar body 10 is half cylindrical and half shaft-shaped, with an internal thread at the cylindrical end and an external thread at the shaft end. In actual production, the three technical solutions can be analyzed from three aspects: stress characteristics, cost, and processing, installation and maintenance, in order to determine the applicable scenarios.

[0046] In terms of stress characteristics, when the first thread 100 is an internal thread, the stress is concentrated at the meshing point between the inner wall of the columnar body 10 and the part to be connected, resulting in higher tensile strength, but the columnar body 10 is subjected to greater shear force.

[0047] From the perspective of cost and processing, the cost of internal thread processing of the cylindrical body 10, such as tapping, is relatively low.

[0048] In terms of installation and maintenance, when the first thread 100 is an internal thread, the cylindrical body 10 can be installed directly by tightening, which is relatively simple. However, when the first thread 100 is an external thread, the cylindrical body 10 needs to be screwed into the part to be connected, which requires higher precision in the thread.

[0049] It can be selected according to actual work needs and work environment, and has high applicability and wide range.

[0050] Furthermore, the first thread 100 is a tapered thread with a triangular tooth profile. Compared to straight threads in the prior art, the tapered thread has the following three advantages: First, the tapered thread and the triangular tooth profile have a synergistic effect. When the tapered thread is tightened, the tapered angle gradually compresses, generating radial pressure. The sharp tooth crest and root of the triangular tooth profile can more effectively embed into the mating surface and fill tiny gaps, thus providing good sealing and further optimizing connection stability. Second, compared to trapezoidal or rectangular threads, the smaller tooth flank angle of the triangular tooth profile increases the frictional resistance between the thread pairs. Combined with the wedging effect of the tapered angle, it can effectively resist loosening caused by axial loads. Third, although the contact surface of the triangular tooth profile is smaller than that of the trapezoidal thread, its symmetrical structure can disperse axial force in the tapered fit, reduce stress concentration, and extend the life of the connected parts.

[0051] The taper of the tapered thread is determined by the size and material properties of the parts to be connected.

[0052] Furthermore, the taper satisfies the following formula:

[0053]

[0054] Where θ is the taper, k is the correction factor, and σ a denoted as denoted as the allowable stress of the parts to be connected, d as the diameter of the parts to be connected, E as the elastic modulus of the material of the parts to be connected, and μ as the friction coefficient of the tapered thread contact surface.

[0055] By further deriving the formula for calculating the taper, the desired taper can be accurately calculated, and the connection effect between the columnar body 10 and the part to be connected can be predicted. The result is accurate, which not only reduces the usage cost brought about by experiments, but also reduces the reliance of skilled workers on technology and lowers labor costs.

[0056] In this embodiment, by setting a tapered thread at the end of the columnar body 10, when the part to be connected is connected to the columnar body 10, during the thread engagement process, firstly, the thread contact surface is gradually pressed together to achieve high-precision centering and uniform force distribution. Secondly, the tapered structure forms a self-locking structure through screwing, which enhances the preload between the threads, significantly improves the pull-out resistance and torsional resistance, and reduces the risk of installation misalignment.

[0057] At the same time, this application also concludes that the taper of the thread plays a crucial role in achieving the optimal connection between the cylindrical body 10 and the part to be connected. Therefore, further research shows that the size of the taper is determined by the size and material properties of the part to be connected, which means that the required connection effect can be achieved by changing the size and material properties according to actual working needs, making it highly applicable.

[0058] Example 2

[0059] See Figures 1 to 3 This embodiment claims to protect a support anchor bolt. The application embodiment describes a connector including a connecting sleeve and at least two anchor bolt bodies 20. The anchor bolt bodies 20 are MG400 type anchor bolts made of Q235 steel. The anchor bolt bodies 20 are coaxially arranged, and the near ends are provided with second threads 200 adapted to the first thread 100. The second thread 200 is aligned and engaged with the first thread 100 at the corresponding end of the connecting sleeve. The surfaces of the first thread 100 and the second thread 200 are covered with an anti-corrosion coating. A sealing element is provided between the anchor bolt body 20 and the connecting sleeve.

[0060] The specific installation method of the support anchor in this embodiment is as follows: Taking the columnar body 10 protected by technical solution one in embodiment one, which has internal threads at both ends, as an example, firstly, one end of the two anchor bodies 20 is machined into a tapered external thread, and the inside of the matching columnar body 10 is machined into a tapered internal thread, the taper of which ensures complete matching with the external thread of the anchor body 20. Secondly, the tapered external threads at the ends of the two anchor bodies 20 are inserted into the tapered internal threads connecting the columnar body 10, and the anchor bodies 20 are rotated clockwise until they are fully tightened. During the tightening process, as the tapered threads gradually engage, the thread contact surface generates radial clamping force, forming a self-locking structure. Finally, after tightening, a preset torque is applied using a torque wrench to make the preload between the threads reach the design requirements, completing the high-precision connection.

[0061] Example 3

[0062] This embodiment provides a specific technical solution based on Embodiment 2:

[0063] Step 1: Select two MG400 type anchor rods as anchor rod bodies 20. The diameter of the anchor rod body 20 is 22mm. The end of the anchor rod body 20 is provided with a second thread 200, wherein the second thread 200 is an external tapered thread, the outer diameter of the large end of the second thread 200 is 21mm, the outer diameter of the small end of the second thread 200 is 19mm, the length of the second thread 200 is 40mm, the pitch is 2mm, the tooth profile of the second thread 200 is triangular, and the tooth apex angle is 60°.

[0064] Step 2: Select a 50CrV high-strength alloy steel outer tube as the columnar body 10, with a tensile strength of not less than 1280MPa. The outer diameter of the columnar body 10 is 25mm, and the length of the columnar body 10 is 90mm. The columnar body 10 is provided with a first thread, and the first thread 100 matches the second thread 200. The outer diameter of the large end of the first thread 100 is 21mm, the outer diameter of the small end of the first thread 100 is 19mm, and the pitch is 2mm.

[0065] Step 3: Calculate the optimal connection taper according to the taper calculation formula. For the Q235 steel MG400 anchor rod, the elastic modulus of the component to be connected is approximately 2.0 × 10⁵ MPa. Referring to the "Technical Specification for Rock and Soil Anchors" GB / T35056-2018, the allowable stress of the MG400 anchor rod is between 400 MPa and 450 MPa. Here, a safety factor of 2.0 is used, meaning the allowable stress of the component to be connected is 400 MPa. The diameter of the anchor rod body is 20 mm, which corresponds to the diameter of the component to be connected is 22 mm. mm; According to the "Standard for Measurement of Friction Coefficient", the friction coefficient of the tapered thread contact surface is between 0.05 and 0.25, of which the friction coefficient between dry steel and steel is generally between 0.15 and 0.25. Here, we take 0.2; The correction coefficient K is found to be between 0.45 and 0.5 through experiments. Based on the deviation, we take the correction coefficient as 0.5. Substituting the above values ​​into the taper calculation formula, the theoretical optimal taper is 0.055. For ease of processing, we choose to set the taper to 0.05, i.e., 1:20.

[0066] It is worth noting that, under extreme conditions, the rationality of this formula is verified. If the coefficient of friction approaches 0, that is, the connection between the columnar body 10 and the anchor body 20 is absolutely smooth, then the taper approaches infinity, which means that external processes are required to force locking. If the allowable stress of the parts to be connected approaches infinity, that is, the strength of the anchor body 20 is extremely high, then the taper also approaches infinity. The connection efficiency can be improved by making the taper steeper.

[0067] Step 4: Verification Results. To verify the rationality of maximizing strength when the thread taper is 1:20, the dimensions of the anchor body 20 and the columnar body 10 described in Example 3 were selected. Meshing threads were formed on the anchor body 20 and the columnar body 10 using straight threads, tapered threads with a taper of 1:10, tapered threads with a taper of 1:20, tapered threads with a taper of 1:30, and tapered threads with a taper of 1:40. Tensile tests were then conducted on each thread after meshing, and the maximum tensile displacement and maximum tensile load were measured. Five different taper threads were obtained and tensile tests were performed on each. The test results are shown in Table 1. Based on Table 1, the following conclusions are drawn. Figure 4 Clearly, compared with the other four types of threads, the 1:20 taper helical thread has a higher maximum tensile displacement and maximum tensile load at failure when it breaks in a tensile test. This proves the superiority of the 1:20 thread taper and the rationality of the above taper formula.

[0068] Table 1 Maximum tensile displacement and maximum tensile load for each thread type

[0069] Thread type Maximum tensile displacement (mm) Maximum tensile load (kN) straight thread 8.5 126.1 Thread taper 1:10 8.9 159 Thread taper 1:20 21.1 191.8 Thread taper 1:30 12.1 173.3 Thread taper 1:40 10 168.4

[0070] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A connection, characterized in that The application relates to a connecting sleeve, which comprises a columnar body (10), and a first thread (100) arranged at the end of the columnar body (10) and used for aligning and engaging with a connecting piece; the first thread (100) is a tapered thread, wherein the taper of the tapered thread is determined by the size and material attribute of the connecting piece, and the taper satisfies the following formula: 0.001<=taper<=0.

01. wherein is the taper, is the correction factor, is the allowable stress of the piece to be connected, is the diameter of the piece to be connected, is the modulus of elasticity of the material of the piece to be connected, is the friction coefficient of the taper thread contact surface.

2. A connector according to claim 1, wherein The first thread (100) is an internal thread or an external thread; when the first thread (100) is an internal thread, the columnar body (10) provided with the first thread (100) is partially in a cylindrical shape; When the first thread (100) is an external thread, the columnar body (10) provided with the first thread (100) is partially in an axial shape.

3. A connection according to any one of claims 1-2, characterized in that The tooth shape of the tapered thread is triangular.

4. A connector according to any one of claims 1-2, characterised in that The columnar body (10) is a 50CrV high-strength alloy steel sleeve.

5. A connector according to any one of claims 1-2, wherein An anti-skid piece is arranged on the outer cylinder wall of the columnar body (10).

6. A connector according to claim 5, wherein The anti-skid piece is an anti-skid sleeve or an anti-skid knurl.

7. A support anchor rod, which is provided with a connecting piece according to any one of claims 1-6, and comprises a columnar body (10) and at least two anchor rod bodies (20); the anchor rod bodies (20) are coaxially arranged, and are provided with a second thread (200) at the proximal end, which is matched with the first thread (100); the second thread (200) is aligned and engaged with the first thread (100) at the corresponding end of the connecting sleeve; and the at least two anchor rod bodies (20) constitute the connecting piece.

8. A support anchor according to claim 7, characterised in that The anchor rod body (20) is an MG400 type anchor rod.

9. A support anchor according to claim 8, characterised in that, The surfaces of the first thread (100) and the second thread (200) are covered with an isolation layer.

10. A support anchor according to claim 9, characterised in that A sealing piece is arranged between the anchor rod body (20) and the connecting sleeve.

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