Method for the use of a pre-tightening nut in a mechanical joint for the gapless connection of the end of a precast concrete pile

Abstract

The application discloses a pre-tightening nut, which comprises a pre-tightening nut body of sleeve structure, an insertion cavity is arranged on the pre-tightening nut body, a pre-tightening nut connecting part and a pre-tightening nut driving part are arranged on the outer wall of the pre-tightening nut body; an external thread for thread connection with a large nut is arranged on the pre-tightening nut connecting part; a transmission structure for driving a driving component to rotate the pre-tightening nut from the pre-tightening nut side is arranged on the pre-tightening nut driving part. The pre-tightening nut disclosed by the application effectively eliminates the gap between the plug and the pre-tightening nut, so that when the mechanical joint with the pre-tightening nut is used to connect the precast concrete pile, the connection part of the precast concrete pile will not crack and generate cracks under the action of pulling force, shearing force or bending force.

Description

Technical Field

[0001] This invention relates to the field of precast component technology, and in particular to a method for using pre-tightened nuts in mechanical joints for gapless connection of precast concrete pile ends. Background Technology

[0002] Most engineering piles (precast piles) are multi-section piles, and the ends of existing precast concrete piles are generally connected quickly between piles using mechanical joints.

[0003] Article 5.1.7 of the "Technical Standard for Prestressed Concrete Pipe Piles" (JGJ / T406-2017) stipulates that for prestressed pipe piles that are strictly required to be free of cracks, the crack control level should be Level I. Article 5.1.8 stipulates that when the pipe pile is under axial tension, the crack control level is Level I; when the pipe pile is under bending, the crack control level is Level II for pipe piles in weakly corrosive environments and above, and Level I for pipe piles in moderately and strongly corrosive environments and above.

[0004] Article 3.4.4 of the "Code for Design of Concrete Structures" (GB50010-2015) stipulates that the stress crack control level of the cross-section of structural members is divided into three levels, and the classification and requirements shall comply with the following provisions:

[0005] Level 1 – For components that are strictly required to be free of cracks, when calculated according to the standard load combination, the concrete at the tension edge of the component should not generate tensile stress.

[0006] Level 2 – For components that are generally required to be free of cracks, when calculated according to the standard load combination, the tensile stress in the concrete at the tension edge of the component should not exceed the standard value of the tensile strength of the concrete.

[0007] Level 3 – Components Allowed to Crack: For reinforced concrete components, when calculating based on the quasi-permanent load combination and considering the long-term effects, the maximum crack width of the component should not exceed the maximum crack width limit specified in Table 3.4.5 of this code. For prestressed concrete components, when calculating based on the standard load combination and considering the long-term effects, the maximum crack width of the component should not exceed the maximum crack width limit specified in Clause 3.4.5 of this code; for prestressed concrete components in Class 2a environments, calculations should also be performed based on the quasi-permanent load combination, and the tensile stress in the concrete at the tension edge of the component should not exceed the standard value of the tensile strength of the concrete. Clause 3.4.5 of this code specifies that the crack control level for prestressed concrete structures is Level 1 in Class 3a and 3b environments, and Level 2 in Class 2b environments. Cracks are not allowed in either Level 1 or Level 2 crack control levels. In Class 2a environments, the crack control level is Level 3, with a maximum crack width limit of 0.1 mm. In Class 1 environments, the crack control level is Level 3, with a maximum crack width limit of 0.2 mm.

[0008] like Figure 31 The diagram shows the first structural form of an existing mechanical joint, including a large nut 2, a small nut 21, a plug rod 1, and a connector 90. One end of the plug rod is threaded to the small nut, and the other end has a plug. The connector is threaded to the large nut, and the end of the connector inside the large nut has multiple elastic clips. The plug is inserted from one end of the connector and can abut against the elastic clips to achieve a snap-fit ​​between the plug rod and the connector. This mechanical joint allows for the rapid connection of two precast concrete piles. However, this type of mechanical joint for connecting precast concrete piles has the following shortcomings: 1. When using this mechanical joint for connecting precast concrete piles, due to factors such as the inclination of the pile end face, the plug rod may be over-inserted into the connector. When this occurs, the precast concrete pile, under the action of tensile force, shear force, or bending force, will cause axial clearance in all or part of the mechanical joint at the pile connection end face, resulting in axial clearance at the precast concrete pile connection, causing cracks to form at the mechanical joint connection. Specifically, for example... Figure 31 The diagram shows the insertion of the plug rod into the connector. After the plug rod is inserted into the connector, an axial gap Δh will be formed between the end of the elastic clip and the stop surface of the plug. As a result, when an external force is applied, a corresponding axial gap will also be generated between the connecting end faces of the precast concrete pile. This makes it impossible to meet the requirements of Article 5.1.7 of the "Technical Standard for Prestressed Concrete Pipe Piles" JGJ / T406-2017, which stipulates that for prestressed pipe piles that are strictly required to be free of cracks, the crack control level should be Level 1; Article 5.1.8 stipulates that when the pipe pile body is under axial tension, the crack control level should be Level 1; when the pipe pile body is under bending... 1. The crack control level for pipe piles in weakly corrosive environments and above is Level II, while the crack control level for pipe piles in moderately and strongly corrosive environments and above is Level I; 2. Since the large nut and the connector, and the small nut and the insert rod are both connected by threads, there will be a certain axial clearance in the threaded connection. Therefore, when the mechanical joint is subjected to pull-out force, the axial clearance of the threaded connection will also cause a corresponding axial clearance between the connecting end faces of the precast concrete pile, further increasing the size of the cracks at the connection of the precast concrete pile, making it impossible to meet the crack control requirements in the "Technical Standard for Prestressed Concrete Pipe Piles" when used for precast concrete pile connections; 3. If Figure 32 As shown, when using this mechanical connector to connect precast concrete piles, there is a problem that the plug of the insert rod is not properly inserted into the connector. That is, when the insert rod is inserted into the connector, the end of the elastic clip does not enter the annular groove of the insert rod. Therefore, the insert rod and the connector cannot be engaged, resulting in the failure of the pile connection.

[0009] like Figure 33The diagram shows a second structural form of an existing mechanical joint, including a large nut 2, a small nut 21, a plug rod 1, an intermediate nut 91, an elastic element 92, and a clip 93. One end of the plug rod is threaded to the small nut, and the other end has a plug. The intermediate nut is threaded to the large nut, and the intermediate nut has a tapered snap-fit ​​surface at one end of the large nut. An elastic element and multiple clips are located within the receiving cavity of the large nut. The elastic element abuts the multiple clips against the tapered snap-fit ​​surface of the intermediate nut. The plug is inserted from one end of the intermediate nut and can compress the elastic element, allowing the plug to pass through the space formed by the multiple clips and snap-fit ​​between the intermediate nut and the plug, thus achieving a rapid connection of two precast concrete piles. However, using this type of mechanical joint for connecting precast concrete piles has the following drawbacks: 1. During the insertion of the plug rod into the intermediate nut, there is a situation where the central axis xx of the plug rod and the central axis yy of the intermediate nut are not aligned. Therefore, if... Figure 33 , Figure 34 and Figure 35 As shown, during the insertion of the plug into the middle nut, the card closer to the plug axis contacts the plug first, while the card further away from the plug axis contacts the plug later. The lower card contacts the plug first and compresses the spring under the action of the plug, while the upper card contacts the plug later. Therefore, the following may occur: Figure 34 The card on one side of the diagram enters between the plug and the center nut, while the card on the other side cannot enter between the plug and the center nut; or, as shown... Figure 35 The different engagement positions of the multiple clips, plugs, and intermediate nuts shown lead to pile connection failure or low connection strength of the mechanical joint. Consequently, when the precast concrete pile is subjected to tensile, shear, or bending forces, axial slippage occurs between the insert rod and the clip of the mechanical joint. This results in axial clearance in all or part of the mechanical joint at the pile connection end face, causing cracks to form at the connection point of the precast concrete pile mechanical joint. 2. When the plug is inserted into the intermediate nut and engaged with the clip, there is no locking between the plug, clip, and intermediate nut (between the plug and clip). (The force is very small). Therefore, when the insert is subjected to tensile, shear, or bending forces, the plug of the insert will squeeze the card, causing the card to slide axially relative to the plug. This results in axial clearance at all or part of the mechanical joint at the pile connection end face when the precast concrete pile is subjected to tensile, shear, or bending forces. Consequently, axial clearance also occurs at the precast concrete pile connection, leading to cracking at the mechanical joint connection. 3. For example... Figure 35 As shown, since both the card and the plug have conical or cylindrical contact surfaces, and because the contact position between the card and the plug is uncertain, the contact surfaces of the card and the plug will not perfectly align when they are engaged. Figure 36As shown in the figure, curves Q1 to Q5 represent the cross-sectional radius curves at different positions of the plug's contact surface, and curve J represents the cross-sectional radius curve at a certain position of the card. As shown in the figure, when curve J is at position Q1, curve J is completely in contact with Q1. When curve J is at positions Q2 to Q5, the gap between curve J and curve Q gradually increases. In other words, when the card is at different positions of the plug, the contact state between the card and the plug is different, meaning that it cannot be guaranteed that the contact surface of the card and the contact surface of the plug are completely in contact. In other words, the contact between the card and the plug is line contact. When the mechanical joint is subjected to tensile, shear, or bending forces, axial slippage will occur between the card and the plug, or the card may partially embed into the plug (or the card may deform under force), resulting in axial clearance in the mechanical joint. That is, when using this type of mechanical joint to connect precast concrete piles, when subjected to tensile, shear, or bending forces, a corresponding axial clearance will also occur between the connecting end faces of the precast concrete piles, causing cracks to form at the mechanical joint connection of the precast concrete piles. 4. Since the large nut and the middle nut, and the small nut and the insert rod are all connected by threads, the threaded connection will also have a certain axial clearance. Therefore, when the mechanical joint is subjected to tensile, shear, or bending forces, the axial clearance of the threaded connection will also cause a corresponding axial clearance between the connecting end faces of the precast concrete piles, resulting in cracks to form at the mechanical joint connection of the precast concrete piles. This mechanical structure has several shortcomings, therefore, when using this mechanical joint for connecting precast concrete piles, the connection may fail to meet the requirements of Article 5.1.7 of the "Technical Standard for Prestressed Concrete Pipe Piles" (JGJ / T406-2017), which stipulates that for prestressed pipe piles with strict requirements to be free of cracks, the crack control level should be Level 1; Article 5.1.8 stipulates that when the pipe pile is under axial tension, the crack control level should be Level 1; and when the pipe pile is under bending, the crack control level should be Level 2 for pipe piles in weakly corrosive environments and above, and Level 1 for pipe piles in moderately and strongly corrosive environments and above.

[0010] Existing mechanical joints have axial clearance issues, which cause gaps to form at the joints of precast concrete piles when subjected to tensile, shear, and / or bending forces. Since precast pile foundations are underground concealed works, the precast piles themselves cannot be repaired.

[0011] Safety hazards of cracks in precast concrete pile joints in building pile foundations:

[0012] When precast concrete piles are subjected to bending and shear forces, the axial gap at the joint of the precast concrete pile due to the aforementioned mechanical joint will cause cracks at the connection of the precast concrete pile, which will lead to the pile and the pile end face being subjected to local structural compressive forces; causing damage or cracking of the concrete at the pile end face, resulting in safety hazards in the building pile foundation.

[0013] When precast concrete piles are subjected to tensile forces, it is impossible to ensure that the axial gaps generated by the aforementioned mechanical joints are completely consistent. Furthermore, the design value of the axial tensile bearing capacity of the precast pile body is based on the total number of main reinforcement bars (the number of mechanical joints). As a result, the aforementioned mechanical joints will be broken one by one when subjected to tensile forces, leading to potential safety hazards in the building pile foundation.

[0014] When precast concrete piles are subjected to bending, shear, and tensile forces, axial gaps at the pile joints can lead to cracks. This can cause groundwater intrusion and corrosion of mechanical connections and / or the main reinforcement of the precast pile, making it difficult to guarantee the pile's durability. Specifically, according to Table 4.1.18 of the "Technical Specification for Building Pile Foundations" (JGJ94-2008), the annual corrosion rate of steel piles is 0.05~0.1 mm when the steel pile is above ground and in an environment without corrosive gases or corrosive volatile media. / y; When the steel pile is located below the ground and above the water level, the single-sided corrosion rate is 0.05 mm / y; when the steel pile is located below the ground and below the water level, the single-sided corrosion rate is 0.03 mm / y; when the steel pile is located below the ground and in a water level fluctuation zone, the single-sided corrosion rate is 0.1~0.3 mm / y. Therefore, it can be seen that when precast concrete piles develop cracks due to the axial gap of the mechanical joint, the mechanical joint and / or main reinforcement will be rapidly corroded, making it difficult to guarantee the durability of the precast pile. The severity of the damage is self-evident. Summary of the Invention

[0015] This invention addresses the problems caused by axial clearance in existing mechanical joint connection mechanisms, which can lead to cracks at the connection of precast concrete piles, resulting in corrosion of the main reinforcement and / or mechanical joints, and localized pressure on the pile end face. It proposes a pre-tightening nut to solve the safety hazards caused by the axial clearance in existing mechanical joint connections.

[0016] The technical means employed in this invention are as follows:

[0017] A preload nut includes a preload nut body with a sleeve structure, an insertion cavity on the preload nut body, and a preload nut connecting part and a preload nut driving part on the outer wall of the preload nut body;

[0018] The preloaded nut connection part is provided with an external thread for threaded connection with the large nut;

[0019] The preload nut drive unit is provided with a transmission structure for driving components to drive the preload nut to rotate from the side of the preload nut.

[0020] Furthermore, the transmission structure is an engagement or pushing structure located on the outer wall or end of the pre-tightening nut drive part.

[0021] Furthermore, the engagement or pushing structure is a pushing groove, engagement teeth, a prying protrusion, or a conical tooth.

[0022] Furthermore, the transmission structure and the preload nut drive unit are either an integral structure or separate structures.

[0023] Furthermore, the outer wall of the preload nut drive unit is provided with a pushing groove; or,

[0024] The outer wall of the preload nut drive unit is provided with meshing teeth; or...

[0025] The outer wall of the preload nut drive unit is provided with a first actuating protrusion; or...

[0026] The end of the preload nut drive unit is provided with a first conical tooth; or...

[0027] The end of the pre-tightening nut drive unit is provided with a second actuating protrusion.

[0028] Furthermore, the preload nut drive unit is fitted with an intermediate sleeve, which can drive the preload nut drive unit to rotate synchronously, and the intermediate sleeve and the preload nut drive unit can move relative to each other axially.

[0029] The outer wall of the intermediate sleeve is provided with a pushing groove; or,

[0030] The outer wall of the intermediate sleeve is provided with interlocking teeth; or,

[0031] The outer wall of the intermediate sleeve is provided with a first actuating protrusion; or...

[0032] The end of the intermediate sleeve is provided with a first conical tooth; or,

[0033] The end of the intermediate sleeve is provided with a second actuating protrusion.

[0034] Furthermore, the intermediate sleeve and the preload nut drive unit are connected by a key or teeth.

[0035] Furthermore, one end of the preload nut body is provided with an elastic clip; or,

[0036] One end of the preload nut body is provided with an elastic clip, and the inner wall of the elastic clip is provided with teeth.

[0037] Furthermore, the insertion cavity of the preload nut body is provided with a helical toothed groove for accommodating the snap-fit ​​spring.

[0038] Furthermore, the insertion cavity of the preload nut body is provided with a retaining ring receiving groove for accommodating the retaining ring.

[0039] Compared with the prior art, the pre-tightening nut disclosed in this invention has the following beneficial effects: The pre-tightening nut disclosed in this application, due to the presence of a transmission mechanism, can be driven from the side by a driving component after the plug is inserted into the cavity and radially engaged with the locking mechanism, causing the pre-tightening nut to move axially along the large nut, thereby locking the plug and the locking mechanism in the axial direction of the large nut. This effectively eliminates the axial gap between the plug, the locking mechanism, and the pre-tightening nut. Furthermore, since the pre-tightening nut, the insertion rod, and the locking mechanism are locked in the axial direction, during the locking process, the pre-tightening nut, the insertion rod, and the locking mechanism will generate [something] in the axial direction. A certain axial force (tightening force) is generated. Under the action of this axial force, the axial gaps between components such as the pre-tightening nut, insert rod, large nut, snap-fit ​​mechanism, and small nut can be effectively eliminated. Therefore, when using the mechanical joint disclosed in this invention for precast concrete pile connection, the precast concrete pile connection will not crack under tensile, shear, or bending forces. This ensures that the mechanical joint disclosed in this invention meets the relevant requirements for crack level control in the "Technical Standard for Prestressed Concrete Pipe Piles" JGJ / T406-2017. Furthermore, it eliminates the problem of gaps generated in existing mechanical joint connections, which cause cracks at the precast concrete pile joint and pose safety hazards to the building pile foundation. Attached Figure Description

[0040] Figure 1 This is a front view of the first embodiment of the preload nut disclosed in this invention, where the transmission structure is a meshing tooth;

[0041] Figure 2 This is an axial view of the first embodiment of the preload nut disclosed in this invention;

[0042] Figure 3 This is a cross-sectional view of an embodiment of a mechanical joint having the preload nut disclosed in this invention, in which the insert rod and the preload nut are not axially locked.

[0043] Figure 4 for Figure 3 A schematic diagram of the mechanical joint insert rod and the preload nut being axially locked together, as disclosed in the document;

[0044] Figure 5 This is a front view of a second embodiment of the preload nut disclosed in this invention, in which the transmission structure is a bevel gear;

[0045] Figure 6 This is an axial view of a second embodiment of the preload nut disclosed in this invention;

[0046] Figure 7 The drive mechanism disclosed in this invention is a bevel gear drive rod when the transmission structure of the preloaded nut is a bevel gear.

[0047] Figure 8 This is a front view of a third embodiment of the preload nut disclosed in this invention. The transmission structure in the figure is a protrusion provided at the end of the preload nut drive part.

[0048] Figure 9 This is an axial view of the third embodiment of the preload nut disclosed in this invention;

[0049] Figure 10 This is a structural diagram of a mechanical joint having a preload nut according to the third embodiment of the present invention;

[0050] Figure 11 This is a front view of the fourth embodiment of the preload nut disclosed in this invention. The transmission structure in the figure is a groove provided on the outer wall of the preload nut drive part.

[0051] Figure 12 This is a schematic diagram of the drive mechanism for the preload nut according to the fourth embodiment of the present invention;

[0052] Figure 13 This is a schematic diagram of the second driving method of the preload nut according to the fourth embodiment of the present invention;

[0053] Figure 14 This is a schematic diagram of the third driving method for the preload nut according to the fourth embodiment of the present invention;

[0054] Figure 15 This is a front view of the fifth embodiment of the preload nut disclosed in this invention. The transmission structure in the figure is a protrusion provided on the outer wall of the preload nut drive part.

[0055] Figure 16 This is a front view of another embodiment of the preload nut disclosed in this invention. In the figure, the preload nut drive part is fitted with an intermediate sleeve, and the intermediate sleeve is provided with engagement teeth.

[0056] Figure 17 for Figure 16 A structural diagram of the preload nut with the intermediate sleeve removed;

[0057] Figure 18 This is a front view of another embodiment of the preload nut disclosed in this invention. In the figure, the preload nut drive part is fitted with an intermediate sleeve, and the intermediate sleeve is provided with conical teeth.

[0058] Figure 19This is a front view of another embodiment of the preload nut disclosed in this invention. In the figure, the preload nut drive part is covered with an intermediate sleeve, and the intermediate sleeve is provided with a groove.

[0059] Figure 20 This is a front view of another embodiment of the preload nut disclosed in this invention. In the figure, the preload nut drive part is fitted with an intermediate sleeve, and a protrusion is provided on the end of the intermediate sleeve.

[0060] Figure 21 This is a front view of another embodiment of the preload nut disclosed in this invention. In the figure, the preload nut drive part is fitted with an intermediate sleeve, and the side wall of the intermediate sleeve is provided with a protrusion.

[0061] Figure 22 This is a front view of another embodiment of the preload nut disclosed in this invention. In the figure, one end of the preload nut body is provided with an elastic clip, and the inner wall of the elastic clip is provided with clip teeth.

[0062] Figure 23 For having Figure 22 The structural diagram of the mechanical joint for the preload nut is disclosed in the document;

[0063] Figure 24 For having Figure 22 A schematic diagram of the tooth relationship between the insert rod of the mechanical connector of the preload nut and the tooth of the preload nut before axial locking, as disclosed in the paper;

[0064] Figure 25 For having Figure 22 A schematic diagram of the tooth relationship between the insert rod of the mechanical connector of the preload nut and the preload nut after axial locking, as disclosed in the paper;

[0065] Figure 26 This is a front view of another embodiment of the preload nut disclosed in this invention. The insertion cavity of the preload nut body is provided with a retaining ring receiving cavity.

[0066] Figure 27 For having Figure 26 A schematic diagram of the insertion rod of the mechanical connector for the preload nut before axial locking of the preload nut, as disclosed in the paper;

[0067] Figure 28 For having Figure 26 A schematic diagram of the insert rod of the mechanical connector of the preload nut after axial locking with the preload nut, as disclosed in the paper;

[0068] Figure 29 This is a front view of another embodiment of the preload nut disclosed in this invention. The insertion cavity of the preload nut body is provided with a snap-fit ​​spring receiving cavity.

[0069] Figure 30 For having Figure 29 A schematic diagram of the mechanical joint of the preload nut disclosed in the document;

[0070] Figure 31 This is a structural diagram of the first type of existing mechanical connector, with the plug in an over-insertion state.

[0071] Figure 32 This is a structural diagram of the first type of existing mechanical connector, with the plug in a partially inserted state.

[0072] Figure 33 This is a structural diagram of the existing second type of mechanical connector, showing the insertion process when the axis of the insertion rod and the axis of the intermediate nut are not collinear.

[0073] Figure 34 The diagram shows the structure of the second type of mechanical connector. In the diagram, the plug of the insertion rod contacts the lower card first, preventing the lower card from entering between the plug and the middle nut.

[0074] Figure 35 This is a structural diagram of the existing second type of mechanical connector, in which multiple clips are held at different positions between the plug and the intermediate nut;

[0075] Figure 36 This is a schematic diagram showing the contact state between the card and the plug contact surface of the existing second type of mechanical connector;

[0076] In the diagram: 1. Preload nut; 10. Preload nut body; 11. Insertion cavity; 12. Preload nut connecting part; 13. Preload nut driving part; 130. Pushing groove; 131. First actuating protrusion; 132. Second conical tooth; 133. Second actuating protrusion; 14. Intermediate sleeve; 15. Keyway; 16. Elastic clip; 17. Clip tooth; 18. Clip ring receiving groove; 2. Insert rod; 20. Plug; 21. Insert rod connecting part; 22. Insert rod base; 23. Second snap-fit ​​surface; 3. Large nut; 30. Receiving cavity; 31. Small nut; 6. Driving component; 60. Lead screw; 61. Toothed rod; 62. Driving rod; 63. Actuating rod; 7. Positioning sleeve; 70. Positioning hole; 8. Precast concrete pile; 80. Precast concrete pile body; 81. Main reinforcement; 82. Driving component receiving groove. Detailed Implementation

[0077] like Figure 1 and Figure 2 The first embodiment of the preload nut disclosed in this invention is shown, including a preload nut body 10 with a sleeve structure, an insertion cavity 11 on the preload nut body 10, and a preload nut connecting part 12 and a preload nut driving part 13 on the outer wall of the preload nut body 10.

[0078] The preload nut connection part 12 is provided with an external thread for threaded connection with the large nut 3;

[0079] The preload nut drive unit 13 is provided with a transmission structure for the drive component 6 to drive the preload nut 1 to rotate from the side of the preload nut 1. In this embodiment, the transmission structure is a meshing tooth 130 provided on the outer wall of the preload nut drive unit 13, the drive component is a lead screw structure, and one end of the preload nut body 10 is provided with an elastic clip 16.

[0080] like Figure 3 and Figure 4 The diagram shows a mechanical connector with the preload nut disclosed in this embodiment, including a large nut 3, a insert rod 2, a small nut 31, and a preload nut 1; one end of the insert rod 2 is threadedly connected to the small nut, and the other end has a snap-fit ​​surface; the preload nut connecting part 12 is threadedly connected to the large nut 3, an elastic clip 16 is placed in the large nut 3, at least a portion of the preload nut driving part 13 is located on the outside of the large nut 3, and the insert rod 2 can be inserted into the preload nut 1. Figure 3The diagram illustrates the use of this mechanical connector for connecting precast concrete piles. After the plug is inserted into the pre-tightening nut, there is a certain axial gap L between the locking mechanism and the locking surface of the plug. The driving component 6 (a lead screw in the diagram) drives the pre-tightening nut driving part under external force, causing the pre-tightening nut to rotate radially (arrow B in the diagram) and move axially along the large nut 3 (arrow C in the diagram). This causes the locking surface of the plug 20 and the end of the elastic card to abut and lock in the axial direction of the large nut 3. In other words, after the plug 20 of the insert rod 2 is radially locked with the elastic card, the pre-tightening nut 1 can move axially along the large nut 3 under the drive of the driving component 6. This axial movement of the pre-tightening nut 1 eliminates the axial gap L between the plug 10 and the locking surface of the elastic card. Furthermore, because the pre-tightening nut and the insert rod are locked in the axial direction, a torque (tightening force) is generated between the pre-tightening nut and the large nut during the locking process. This tightening force causes a certain axial force to be generated between the pre-tightening nut and the insert rod in the axial direction. Under the action of this axial force, the axial gaps between components such as the preload nut, insert rod, large nut, and small nut can be effectively eliminated. For example, the gap between the threaded connection of the preload nut and the large nut (the axial gap of the threaded connection in area E2 of the figure), the gap between the threaded connection of the insert rod base and the small nut (the axial gap of the threaded connection in area E1 of the figure), and the gap between the insert rod plug and the elastic clip of the preload nut, etc. Therefore, when using the mechanical joint disclosed in this invention to connect precast concrete piles, the connection of the precast concrete pile will not crack or generate cracks when subjected to pull-out force, shear force, or bending force. That is, when using the mechanical joint disclosed in this invention to connect precast concrete piles, the connection of the pile has high pull-out resistance, bending resistance, and shear resistance. Therefore, when using the mechanical joint disclosed in this invention to connect precast concrete piles, the relevant requirements for crack level control in the "Technical Standard for Prestressed Concrete Pipe Piles" JGJ / T406-2017 can be met. It also eliminates the problem that gaps are generated in the connection of precast concrete piles due to the existing mechanical joint connection mechanism, which causes cracks at the joints of precast concrete piles and poses a safety hazard to the building pile foundation.

[0081] Furthermore, the transmission structure is an engagement or pushing structure located on the outer wall or end of the pre-tightening nut drive part 13. Specifically, the engagement or pushing structure is a pushing groove, a pushing protrusion, or a conical tooth.

[0082] Specifically, such as Figures 1 to 4The transmission structure of the preload nut disclosed in this invention adopts the first embodiment. In this embodiment, the outer wall of the preload nut drive part is provided with meshing teeth 130, and the drive component is a lead screw 60. The teeth on the lead screw can mesh with the meshing teeth on the outer wall of the preload nut drive part. The rotation of the lead screw can drive the preload nut to rotate, thereby realizing the rotation of the preload nut and its movement along the axial direction of the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0083] like Figure 5 and Figure 6 The transmission structure in the preload nut disclosed in this invention adopts the second embodiment. In this embodiment, the end of the preload nut drive part 13 is provided with a first bevel tooth 132, such as... Figure 7 As shown, in this embodiment, the driving component 6 is a bevel gear driving rod 64. One end of the bevel gear driving rod 64 is provided with a second bevel tooth 640. The second bevel tooth 640 of the bevel gear driving rod 64 can engage with the first bevel tooth 132 from the side of the preload nut 1 and drive the preload nut to rotate during the rotation of the bevel gear driving rod 64, thereby realizing the rotation of the preload nut and its movement along the axial direction of the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut.

[0084] like Figure 8 , Figure 9 and Figure 10 The transmission structure in the preload nut disclosed in this invention adopts a third embodiment. In this embodiment, the end of the preload nut drive part 13 of the preload nut 1 is provided with a second actuating protrusion 133, the drive component 6 is a bevel drive rod 64, and one end of the bevel drive rod 63 is provided with a second bevel tooth 630. The second bevel tooth 630 of the bevel drive rod 63 can engage with the second actuating protrusion 484 from the side of the preload nut 4 and drive the preload nut to rotate during the rotation of the bevel drive rod 63.

[0085] like Figure 11 and Figure 12 The transmission structure in the preload nut disclosed in this invention adopts a fourth embodiment. In this embodiment, the engagement or pushing structure is a pushing groove, specifically as follows: Figure 11As shown, the preload nut drive unit 13 is provided with a push groove 134. The drive component 6 is a toothed rod 61, which is a long column structure. The front end of the long column has multiple protrusions along the axial direction of the rod to form drive teeth 610. The drive teeth 610 are adapted to the push groove 134. The drive teeth of the toothed rod can engage with the push groove 134 from the side of the preload nut 1. During the reciprocating push and pull of the toothed rod 61, the preload nut 1 can be rotated. (When pulling the toothed rod, the toothed rod can be rotated at a certain angle to separate the drive teeth from the push groove. After the toothed rod is pulled out, the toothed rod is rotated again to make the drive rod engage with the push groove and push the toothed rod.) This enables the preload nut to rotate and move along the axial direction of the large nut, thereby locking the plug and the preload nut in the axial direction of the large nut.

[0086] like Figure 13 The transmission structure of the preload nut disclosed in this invention adopts a fifth embodiment. In this embodiment, the outer wall of the preload nut drive part 13 is provided with a push groove 134, the drive component 6 is a drive rod 62, the drive rod is a long column structure, the front end of the long column can be inserted into the push groove 134 from the side of the preload nut 1 in an inclined direction, the reciprocating push of the push rod can make the preload nut rotate, thereby realizing the preload nut moves along the axial direction of the large nut, thereby locking the plug and the preload nut in the axial direction of the large nut.

[0087] like Figure 14 The transmission structure in the preload nut disclosed in this invention adopts a sixth embodiment. In this embodiment, the outer wall of the preload nut drive part 13 of the preload nut 1 is provided with a push groove 134, the drive component 6 is a toothed rod 61, one end of the toothed rod is provided with continuous drive teeth 610, the drive teeth of the toothed rod can engage with the push groove from the side of the preload nut 1 and drive the preload nut to rotate during the rotation of the toothed rod.

[0088] like Figure 15The transmission structure in the preload nut disclosed in this invention adopts a sixth embodiment. In this embodiment, the outer wall of the preload nut driving part 13 of the preload nut is provided with a first actuating protrusion 131. The driving component 6 is an actuating rod 63. The actuating rod 63 can be inserted laterally between two adjacent first actuating protrusions 131 of the preload nut 1 and drive the preload nut to rotate during the rotation of the actuating rod 63. Specifically, a plurality of protrusion structures are uniformly provided circumferentially on the outer wall of the preload nut to form actuating protrusions. The driving component is an actuating rod, which is a long rod structure with the front end of the long rod... The end has a flat structure and can be inserted between two adjacent actuating protrusions, as shown in the figure. The actuating lever can rotate under the drive of an external tool. During the rotation of the actuating lever, one side of the front end face of the actuating lever contacts the corresponding actuating protrusion and drives the preload nut to rotate. When the actuating lever rotates one revolution, the front end face of the actuating lever contacts another adjacent actuating protrusion and continues to drive the preload nut to rotate. That is, the rotation of the actuating lever can drive the preload nut to rotate and move along the axial direction of the large nut, thereby locking the plug and the preload nut (clamping mechanism) in the axial direction of the large nut. The actuating lever can use a structure such as a flathead screwdriver.

[0089] The transmission structure of this application is not limited to the specific structures described above. Any structure that can achieve the function of driving the preload nut to rotate from the side is within the protection scope of this patent. This application will not describe each specific structure that can achieve this function.

[0090] In the above embodiments, the transmission structure is disposed on the preload nut drive unit, that is, the transmission structure and the preload nut drive unit are an integral structure. Alternatively, the transmission structure and the preload nut drive unit can be separate structures.

[0091] Specifically, such as Figure 16 and Figure 17 The diagram shows a first embodiment where the transmission structure and the pre-tightening nut drive unit are separate structures. In this embodiment, the pre-tightening nut drive unit 13 is fitted with an intermediate sleeve 14. The intermediate sleeve 14 and the pre-tightening nut drive unit 13 can be connected by a key or teeth structure, so that the intermediate sleeve 14 can drive the pre-tightening nut drive unit 13 to rotate synchronously, and the intermediate sleeve 14 and the pre-tightening nut drive unit 13 can move relative to each other axially. The outer wall of the intermediate sleeve 14 is provided with meshing teeth 130. The drive component is a lead screw 60. The teeth on the lead screw can mesh with the meshing teeth on the intermediate sleeve. The rotation of the lead screw can drive the pre-tightening nut to rotate, thereby realizing the rotation of the pre-tightening nut and its axial movement along the large nut, thereby locking the plug and the snap-fit ​​mechanism in the axial direction of the large nut. The pre-tightening nut drive unit in the figure is provided with a keyway 15.

[0092] like Figure 18The diagram shows a second embodiment where the transmission structure and the preload nut drive unit are separate structures. In this embodiment, the preload nut drive unit 13 is fitted with an intermediate sleeve 14. The intermediate sleeve 14 and the preload nut drive unit 13 can be connected by a key or teeth, etc., so that the intermediate sleeve 14 can drive the preload nut drive unit 13 to rotate synchronously, and the intermediate sleeve 14 and the preload nut drive unit 13 can move axially relative to each other. The end of the intermediate sleeve 14 is provided with a first bevel tooth, and the intermediate sleeve and the preload nut can be driven to rotate by the bevel tooth drive rod.

[0093] like Figure 19 The diagram shows a third embodiment where the transmission structure and the preload nut drive unit are separate structures. In this embodiment, the preload nut drive unit 13 is fitted with an intermediate sleeve 14. The intermediate sleeve 14 and the preload nut drive unit 13 can be connected by a key or teeth, etc., so that the intermediate sleeve 14 can drive the preload nut drive unit 13 to rotate synchronously, and the intermediate sleeve 14 and the preload nut drive unit 13 can move axially relative to each other. The outer wall of the intermediate sleeve 14 is provided with a pushing groove, and the intermediate sleeve and the preload nut can be driven to rotate by a toothed rod or a drive rod.

[0094] like Figure 20 The diagram shows a fourth embodiment where the transmission structure and the preload nut drive unit are separate structures. In this embodiment, the preload nut drive unit 13 is fitted with an intermediate sleeve 14. The intermediate sleeve 14 and the preload nut drive unit 13 can be connected by a key or teeth or other structure, so that the intermediate sleeve 14 can drive the preload nut drive unit 13 to rotate synchronously, and the intermediate sleeve 14 and the preload nut drive unit 13 can move axially relative to each other. The end of the intermediate sleeve 14 is provided with a second actuating protrusion, which can drive the intermediate sleeve and the preload nut to rotate through a bevel tooth drive rod.

[0095] like Figure 21 The illustration shows a fifth embodiment where the transmission structure and the preload nut drive unit are separate structures. In this embodiment, the preload nut drive unit 13 is fitted with an intermediate sleeve 14. The intermediate sleeve 14 and the preload nut drive unit 13 can be connected by a key or teeth, allowing the intermediate sleeve 14 to drive the preload nut drive unit 13 to rotate synchronously. The intermediate sleeve 14 and the preload nut drive unit 13 can also move axially relative to each other. The outer wall of the intermediate sleeve 14 is provided with a first actuating protrusion 131, which can drive the intermediate sleeve and the preload nut to rotate via an actuating rod. In this application, the preload nut and the transmission structure are set as separate structures, i.e., the preload nut is fitted with an intermediate sleeve, and the intermediate sleeve is equipped with a transmission mechanism. The intermediate sleeve and the preload nut can be processed separately, reducing processing difficulty and production costs. Furthermore, due to the separate structure, the intermediate sleeve can be made smaller, while the preload nut can achieve a larger stroke.

[0096] exist Figure 1 and Figure 2 The form of the preload nut and the plug rod being snapped together disclosed in the first embodiment is provided. In this embodiment, one end of the preload nut body 10 is provided with an elastic card 16. The snapping surface at the end of the elastic card can abut against the snapping surface on the plug rod to realize the connection between the plug rod and the preload nut.

[0097] like Figure 22 and Figure 23 This is a second embodiment of the preload nut and insert rod engagement method disclosed in this invention. One end of the preload nut body 10 is provided with an elastic clip 16, and the inner wall of the elastic clip 16 is provided with locking teeth 17. The insert rod is also provided with locking teeth. When the insert rod is inserted into the preload nut, the locking teeth on the elastic clip and the locking teeth on the insert rod can engage with each other. Figure 24 and Figure 25 As shown, before the insert rod is inserted into the preload nut and before it is axially locked, there is a certain axial gap L between the teeth on the insert rod and the teeth on the elastic card. After the drive component drives the preload nut to rotate, so that the preload nut moves along the axial direction of the large nut, the tooth profile of the teeth on the insert rod and the tooth profile of the teeth on the elastic card engage with each other and are axially locked.

[0098] like Figure 26 , Figure 27 and Figure 28 This is a third embodiment of the preload nut and insert rod snap-fit ​​connection disclosed in this invention. The insertion cavity 11 of the preload nut body 10 is provided with a snap ring receiving groove 19 for accommodating a snap ring. The snap ring receiving groove contains a snap ring that can open or close radially. After the insert rod is inserted into the preload nut, the insert rod and the snap ring can snap together. Figure 27 As shown, before the insert rod is inserted into the preload nut and not axially locked, there is a certain axial gap L between the locking surface on the insert rod and the retaining ring. After the drive component drives the preload nut to rotate, causing the preload nut to move along the axial direction of the large nut, the locking surface on the insert rod and the retaining ring engage with each other and are axially locked.

[0099] like Figure 29 and Figure 30 This is the fourth embodiment of the preload nut and insert rod snap-fit ​​method disclosed in this invention. The insertion cavity of the preload nut body 10 is provided with a helical toothed groove 18 for accommodating the snap-fit ​​spring. The snap-fit ​​spring, which can be radially opened or closed, is provided in the helical toothed groove 18. The insert rod is provided with helical teeth. After the insert rod is inserted into the preload nut, the snap-fit ​​spring can clamp onto the insert rod. Before the insert rod is inserted into the preload nut and not axially locked, there is a certain axial gap between the snap-fit ​​spring and the preload nut. After the driving component drives the preload nut to rotate, so that the preload nut moves in the axial direction of the large nut, the insert rod, the snap-fit ​​spring and the preload nut can be axially locked together.

[0100] The above is merely an illustrative description of the structure of the pre-tightening nut in this invention. The pre-tightening nut disclosed in this application is not limited to the above form. The structure of the pre-tightening nut in this application can be any combination of the transmission structure and the snap-fit ​​structure disclosed above. For example, the transmission structure can be a protrusion, a bevel, a meshing tooth, or a pushing groove, and the snap-fit ​​structure can be an elastic card, an elastic card with snap-fit ​​teeth, a snap-fit ​​spring, or a snap-fit ​​ring, etc., in different organic combinations.

[0101] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for using a pre-tightened nut in a mechanical joint for a gapless connection at the end of a precast concrete pile, characterized in that: The preload nut body includes a sleeve structure, the preload nut body is provided with an insertion cavity, and the outer wall of the preload nut body is provided with a preload nut connecting part and a preload nut driving part; The preloaded nut connection part is provided with an external thread for threaded connection with the large nut; The preload nut drive unit is provided with a transmission structure for driving components to drive the preload nut to rotate from the side of the preload nut; After the plug of the mechanical connector is inserted into the insertion cavity of the preload nut and radially engaged with the locking mechanism of the mechanical connector, the transmission structure can be driven from the side of the preload nut by the driving component, so that the preload nut moves along the axial direction of the large nut of the mechanical connector, thereby eliminating the gap between the plug and the locking mechanism in the axial direction of the large nut, and locking the plug and the locking mechanism in the axial direction of the large nut.

2. The method for using the pre-tightening nut according to claim 1 in a gapless mechanical joint for the end connection of precast concrete piles, characterized in that: The transmission structure is an engagement or pushing structure located on the outer wall or end of the pre-tightening nut drive part.

3. The method for using the pre-tightened nut according to claim 2 in a gapless mechanical joint for the end connection of precast concrete piles, characterized in that: The biting or pushing structure is a pushing groove, a pushing protrusion, a biting tooth, or a conical tooth.

4. The method for using the pre-tightened nut according to claim 3 in a gapless mechanical joint for the end connection of precast concrete piles, characterized in that: The transmission structure and the preload nut drive unit can be an integral structure or separate structures.

5. The method for using the pre-tightened nut according to claim 4 in a gapless mechanical joint for the end connection of precast concrete piles, characterized in that: The outer wall of the preload nut drive unit is provided with a pushing groove; or... The outer wall of the preload nut drive unit is provided with meshing teeth; or... The outer wall of the preload nut drive unit is provided with a first actuating protrusion; or... The end of the preload nut drive unit is provided with a first conical tooth; or... The end of the pre-tightening nut drive unit is provided with a second actuating protrusion.

6. The method for using the pre-tightened nut according to claim 4 in a gapless mechanical joint for the end connection of precast concrete piles, characterized in that: The preload nut drive unit is fitted with an intermediate sleeve, which can drive the preload nut drive unit to rotate synchronously, and the intermediate sleeve and the preload nut drive unit can move axially relative to each other. The outer wall of the intermediate sleeve is provided with a pushing groove; or, The outer wall of the intermediate sleeve is provided with interlocking teeth; or, The outer wall of the intermediate sleeve is provided with a first actuating protrusion; or... The end of the intermediate sleeve is provided with a first conical tooth; or, The end of the intermediate sleeve is provided with a second actuating protrusion.

7. The method for using the pre-tightened nut according to claim 6 in a gapless mechanical joint for the end connection of precast concrete piles, characterized in that: The intermediate sleeve and the preload nut drive unit are connected by a key or teeth.

8. The method for using a pre-tightened nut according to any one of claims 1 to 7 in a mechanical joint for a gapless connection at the end of a precast concrete pile, characterized in that: One end of the preload nut body is provided with an elastic clip; or... One end of the preload nut body is provided with an elastic clip, and the inner wall of the elastic clip is provided with teeth.

9. The method for using a pre-tightened nut according to any one of claims 1 to 7 in a mechanical joint for a gapless connection at the end of a precast concrete pile, characterized in that: The insertion cavity of the preload nut body is provided with a helical tooth groove for accommodating the snap-fit ​​spring.

10. The method for using a pre-tightened nut according to any one of claims 1 to 7 in a mechanical joint for a gapless connection at the end of a precast concrete pile, characterized in that: The insertion cavity of the preload nut body is provided with a retaining ring receiving groove for accommodating the retaining ring.

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