A threaded fastener stretching installation device and method

Abstract

The present invention provides a threaded fastener stretching installation device and method, comprising: an internal thread sleeve, the internal thread sleeve being threadedly connected to the threaded fastener; a washer, the washer being located between the internal thread sleeve and the fastener to be fastened, and a drive nut rotation drive assembly being arranged in the washer. The present invention has the following beneficial effects: compared with the traditional hydraulic stretching method, the threaded fastener is stretched by rotating the internal thread sleeve, which improves the portability and installation efficiency of the device and reduces the cost of the device.

Description

Technical Field

[0001] The invention belongs to the technical field of threaded fastener installation, and in particular relates to a threaded fastener stretching installation device and method. Background Art

[0002] There are two main assembly methods for bolted connections: tightening and stretching. The tightening method is to complete the assembly by rotating the bolt head or one end of the nut and applying torque to the other end; the stretching method uses a hydraulic stretching device to directly apply an axial tensile load to the bolt, so that the bolt to which the force is applied is stretched in its elastic deformation zone, and then the nut is screwed in. Compared with the tightening method, the stretching method can usually obtain lower preload dispersion and higher and more uniform connection quality. It is widely used in industrial fields such as shipbuilding, petrochemicals, electricity, metallurgy, bridges, railways and heavy machinery. The stretching method is not affected by the thread friction coefficient and the bolt size tolerance, and can obtain a more accurate bolt load. Multiple bolts can be stretched synchronously to make the whole circle of bolts evenly stressed and obtain a balanced load. Compared with the tightening method, the demand for circumferential space is lower. The residual load and effective load obtained by tightening the bolt by the stretching method are larger than those by the torque method. The stretching method is more suitable for joint applications with high tightening accuracy requirements, which can make the flange evenly stressed to achieve joint and truly prevent leakage.

[0003] The bolt tensioners currently used in the market mainly rely on hydraulic drive to provide the required tensioning force. Hydraulic tensioners are usually composed of hydraulic pumps, oil pipes, hydraulic cylinders and other components. They stretch bolts by applying pressure through hydraulic oil. Such equipment is widely used in the installation and maintenance of large structures.

[0004] The following problems exist during the use of bolt tensioning devices: First, the hydraulic tensioner needs to be used in conjunction with a hydraulic station, and its manufacturing and maintenance costs are high. Especially for small projects or frequent use, the cost of a single installation station is much higher than the installation by tightening with a torque wrench, and its economy is poor, making it difficult to popularize on a large scale; Second, the hydraulic tensioning system is large in size and heavy in weight, making it inconvenient to carry, especially in environments with limited space or restricted operations, such as the top of a wind turbine tower, the top of an iron tower, railway contact network hoisting and other field or high-altitude installation scenarios, where it is difficult for operators to use it conveniently; Third, the hydraulic tensioning system consumes a lot of power and needs to be connected to an external power supply when in use, so it cannot be used in field installation scenarios without power supply facilities; Fourth, the tensile load of the hydraulic system is obtained through pressure conversion, which is affected by external conditions such as temperature, oil pressure fluctuations, and pipeline length, making it difficult to use. In order to provide stable and precise tensile force, it is difficult to use hydraulic tensioners in some occasions where high-precision bolt preload is required. In addition, the lag and unpredictable factors in the hydraulic conversion increase the measurement error and affect the connection quality. Fifth, the scope of application is narrow. The existing hydraulic bolt tensioners are only used as tools for installing large-size bolts above M20. The core reason is that the stretching method is easier to install large bolts, rather than considering that the connection quality of the stretching method is better. Therefore, the scope of application is narrow, and there is no high-quality stretching installation tool developed for the common small-size bolts on the market. Sixth, due to the complexity of the hydraulic system, it is usually necessary to be equipped with hydraulic pumps, oil pipes and other equipment, which requires a lot of preparation work, and each bolt usually needs to be operated separately. The installation process is relatively cumbersome. Low installation efficiency is a significant disadvantage of the hydraulic tensioning system. Summary of the invention

[0005] In view of this, the present invention aims to provide a threaded fastener stretching installation device and method, in order to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A first aspect of the present invention provides a threaded fastener stretching installation device, comprising:

[0008] An internal threaded sleeve, the internal threaded sleeve being threadedly connected to the threaded fastener;

[0009] A gasket is located between the internal thread sleeve and the fastener.

[0010] Furthermore, a pressure sensor is provided between the gasket and the internal threaded sleeve, and the pressure sensor is used to detect the pressure between the threaded sleeve and the gasket.

[0011] Furthermore, a plane bearing is provided between the internal threaded sleeve and the pressure sensor;

[0012] The internal thread sleeve is installed inside the cylinder, and a baffle is fixed at the lower end of the cylinder, and a through hole corresponding to the threaded fastener is opened on the baffle;

[0013] The lower end of the internal threaded sleeve is provided with a guide portion matching the through hole, and the guide portion is located on the inner side of the through hole;

[0014] A positioning groove matching with the gasket ring is formed on the lower end surface of the cylinder, and the gasket ring is located at the inner side of the positioning groove.

[0015] Furthermore, the threaded fastener stretching installation device also includes a first wrench and a second wrench, wherein the first wrench is used to drive the internal thread sleeve to rotate;

[0016] The driving component is a second wrench, and the second wrench is used to drive the nut to rotate.

[0017] Furthermore, a polygonal groove is formed at the upper end of the internal threaded sleeve, and a polygonal column matching the polygonal groove is fixedly provided on the side wall of the first wrench, and the axis of the polygonal column is vertically arranged perpendicular to the axis of the first wrench.

[0018] Furthermore, an opening is provided on the side wall of the gasket ring, and the second wrench passes through the opening and is connected to the nut.

[0019] Furthermore, the inner thread surface of the inner thread sleeve is provided with a lubricating coating;

[0020] The cylinder is provided with a controller, a power module and a buzzer. The pressure sensor and the buzzer are electrically connected to the controller. The power module supplies power to the controller, the buzzer and the pressure sensor.

[0021] A second aspect of the present invention provides a threaded fastener stretching installation method, comprising the following steps:

[0022] S1, the internal thread sleeve is threadedly connected with the threaded fastener;

[0023] S2, rotating the internal thread sleeve to stretch the threaded fastener;

[0024] S3, turn the nut in the tightening direction;

[0025] S4. Remove the internal thread sleeve.

[0026] Further, the S2 comprises the following steps:

[0027] The tensile force of the bolt is detected during the process of rotating the internal threaded sleeve in the tightening direction. When the tensile force reaches a first preset tensile force, the rotation of the internal threaded sleeve is stopped. The first preset tensile force is greater than the target pre-tightening force of the threaded fastener.

[0028] Further, the S3 includes the following steps:

[0029] The nut is rotated in the tightening direction. When the internal thread sleeve detects that the tensile force is the same as the target preload force of the threaded fastener, the rotation of the nut is stopped and the process goes to step S4.

[0030] Compared with the prior art, the threaded fastener stretching installation device and method described in the present invention have the following beneficial effects:

[0031] (1) Compared with the traditional hydraulic stretching method, the threaded fastener stretching and installation device described in the present invention improves the portability and installation efficiency of the device and reduces the cost of the device by rotating the threaded fastener through the internal threaded sleeve.

[0032] (2) The threaded fastener stretching installation device described in the present invention monitors and adjusts the stretching force in real time through a pressure sensor to ensure higher preload accuracy, and is particularly suitable for occasions requiring high preload accuracy.

[0033] (3) The present invention discloses a method for tensioning and installing a threaded fastener, which achieves a first preset tensioning force by rotating the internal threaded sleeve, and then reduces the tensioning force to a target preload by rotating the nut. This method prevents the bolt from breaking while taking into account the deformation gap of the threaded connection surface, thereby improving the installation accuracy of the preload. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0035] Figure 1 It is a schematic diagram of the three-dimensional structure of the device according to an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of a cross-sectional structure of a device according to an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the three-dimensional structure of the first wrench according to an embodiment of the present invention;

[0038] Figure 4 It is a schematic diagram of the three-dimensional structure of the internal thread sleeve according to an embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of the three-dimensional structure of the gasket ring according to an embodiment of the present invention;

[0040] Figure 6 It is a schematic diagram of the three-dimensional structure of the cylinder described in an embodiment of the present invention.

[0041] Description of reference numerals:

[0042] 1. Internal threaded sleeve; 2. First wrench; 3. Second wrench; 4. Spacer; 5. Plane bearing; 6. Pressure sensor; 7. Cylinder; 8. Threaded fastener; 9. Nut; 10. Fastener to be fastened; 101. Polygonal groove; 102. Guide; 201. Polygonal column; 401. Opening; 701. Through hole; 702. Positioning groove; 703. Notch. DETAILED DESCRIPTION

[0043] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing 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. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0046] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0047] like Figure 1-Figure 6 As shown, a threaded fastener 8 stretching installation device includes:

[0048] An internal threaded sleeve 1, which is threadedly connected to a threaded fastener 8;

[0049] The backing ring 4 is located between the internal thread sleeve 1 and the fastener 10.

[0050] There are many types of internal thread sleeves 1 , and different types of internal thread sleeves 1 have different specifications of internal thread holes, which are suitable for threaded fasteners 8 of different specifications.

[0051] The fasteners 10 to be fastened take two flanges as an example, and the threaded fasteners 8 may be a combination of a bolt and a nut 9 threadedly connected, or a combination of bolts threadedly connected at both ends of a screw rod. In this embodiment, a combination of a bolt and a nut 9 threadedly connected is taken as an example.

[0052] A pressure sensor 6 is provided between the backing ring 4 and the internal threaded sleeve 1 . The pressure sensor 6 may be, but is not limited to, an existing annular pressure sensor 6 .

[0053] A plane bearing 5 is provided between the internal thread sleeve 1 and the pressure sensor 6 ; the plane bearing 5 reduces the friction between the internal thread sleeve 1 and the pressure sensor 6 .

[0054] The internal threaded sleeve 1 is installed on the inner side of the cylinder 7. A baffle is fixed at the lower end of the cylinder 7. A through hole 701 corresponding to the threaded fastener 8 is opened on the baffle. A notch 703 is opened on the side wall of the cylinder 7 to facilitate the lead-out of the connecting wire of the pressure sensor 6.

[0055] The outer diameter of the internal threaded sleeve 1 matches the inner diameter of the cylinder 7, and the outer diameter of the annular pressure sensor 6 matches the inner diameter of the cylinder 7. The cylinder 7 serves to limit the annular pressure sensor 6, so that the annular pressure sensor 6 and the internal threaded sleeve 1 are coaxially arranged, thereby ensuring the accurate characterization of the pressure test results. The inner diameter of the annular pressure sensor 6 is larger than the inner diameter of the guide portion 102.

[0056] The lower end of the internal thread sleeve 1 is provided with a guide portion 102 matching the through hole 701, and the guide portion 102 is located on the inner side of the through hole 701. The guide portion 102 passes through the plane bearing 5 and the pressure sensor 6 and is threadedly connected with the threaded fastener 8. The guide portion 102 guides during the rotation of the internal thread sleeve 1 and shortens the distance between the internal thread sleeve 1 and the bolt, and is suitable for bolts with different protruding lengths.

[0057] A positioning groove 702 matching with the gasket 4 is formed on the lower end surface of the cylinder 7 , and the gasket 4 is located on the inner side of the positioning groove 702 .

[0058] The threaded fastener 8 stretching installation device also includes a first wrench 2 and a second wrench 3. The first wrench 2 is used to drive the internal thread sleeve 1 to rotate. The internal thread sleeve 1 can also be driven to rotate by an electric wrench or directly by a motor. The driving component is the second wrench 3, and the second wrench 3 is used to drive the nut 9 to rotate.

[0059] A polygonal groove 101 is formed at the upper end of the internal threaded sleeve 1 (in this embodiment, the polygonal groove 101 is a square groove), and a polygonal column 201 matching the polygonal groove 101 is fixedly provided on the side wall of the first wrench 2 (in this embodiment, the polygonal column 201 is a square column), and the axis of the polygonal column 201 is perpendicular to the axis of the first wrench 2.

[0060] In some embodiments, an opening 401 is provided on the side wall of the gasket 4, and the second wrench 3 passes through the opening and is connected to the nut 9. The second wrench 3 can be, but is not limited to, an existing open-end wrench.

[0061] In other embodiments, the gasket 4 is fixedly installed at the bottom end of the internal threaded sleeve 1, and the driving component is a rotating ring, which is rotatably connected to the inner side of the gasket 4, and a driving hole matching the nut 9 is opened on the rotating ring.

[0062] The inner thread surface of the inner thread sleeve 1 is provided with a lubricating coating, which reduces the friction between the inner thread sleeve 1 and the threaded fastener 8, thereby preventing the threaded fastener 8 from rotating synchronously with the inner thread sleeve 1;

[0063] The cylinder 7 is provided with a controller, a power module and a buzzer. The pressure sensor 6 and the buzzer are electrically connected to the controller. The power module supplies power to the controller, the buzzer and the pressure sensor 6 .

[0064] The cylinder 7 is also provided with a screen and an adjustment panel, which are electrically connected to the controller. The screen is used to display the pressure value of the pressure sensor 6. The first preset stretching force is set through the adjustment panel. When the pressure value of the pressure sensor 6 reaches the first preset stretching force, the controller controls the buzzer to make a sound and flash to remind the operator.

[0065] Working process:

[0066] The implementation of this plan includes the following steps:

[0067] A1. The threaded fastener 8 passes through the fastener 10 and is connected with the nut 9. The washer 4 is installed on the outside of the threaded fastener 8. The internal threaded sleeve 1 is threadedly connected with the threaded fastener 8.

[0068] A2, rotating the internal thread sleeve 1 in the tightening direction to stretch the threaded fastener 8, and stopping the rotation of the internal thread sleeve 1 when the pressure detected by the pressure sensor 6 reaches a first preset tensile force, and the first preset tensile force is greater than the target pre-tightening force of the threaded fastener 8;

[0069] The calculation formula of the first preset tensile force is as follows:

[0070] F1=F0×a;

[0071] Wherein F1 is the first preset tensile force, F0 is the target preload force, a is the calculation coefficient with a value range of 102.5%-115%, and the value of a in this application is 106.67%.

[0072] When the bolt is stretched to the first target preload F1, the internal force of the entire screw is F1. Assuming that the nut is a rigid body and the meshing threads are smooth and flat, if the nut is just tightened to the thread fit state, then after the external tensile load disappears, the preload of the entire bolt is exactly . But in fact, the nut is not a rigid body. When the external tensile load disappears, the internal thread of the nut and the external thread of the bolt re-enter the deformation coordination process, resulting in the decay of the preload. In addition, when the meshing area of ​​the nut is uneven, after the external tensile load is cancelled, part of the preload will be used to offset the contact gap of the rough surface, resulting in further decay of the preload. The decay of the preload caused by deformation coordination and the decay of the preload caused by the engagement of the micro-convex body can be calculated by the estimated value of the gap offset.

[0073] Therefore, in the present invention, the first target preload force Need to exceed the final target preload This is to ensure that the target value can be reached after the preload decays. After that, tighten the nut to make the reading of the tension device drop to In fact, part of this process further increases the preload of the bolt before recession, and the other part is used to offset the engagement of the micro-convex body.

[0074] The calculation method of preload force to offset clearance consumption is:

[0075] ;

[0076] In the formula, Indicates the preload force to offset the gap consumption, is the interfacial gap, is the flexibility of the bolt, is the flexibility of the connected structure.

[0077] In order to simplify the calculation, the stretched thread is approximately regarded as a cylinder, and the flexibility of the bolt is

[0078] ;

[0079] In the formula, is the original length of the thread in the stretched area, is the Young's modulus of the bolt material, is the stress cross-sectional area of ​​the bolt.

[0080] The calculation process of the flexibility of the connected parts is relatively complicated and is related to the material and shape of the connected parts. However, according to the empirical value given by VDI2230, the following formula is usually satisfied:

[0081] ;

[0082] Therefore, the preload force that offsets the clearance consumption for:

[0083] ;

[0084] When the bolt is stretched the first target preload When , it can be regarded as a current tensile load of If the nut is tightened, it is equivalent to applying a new load in the middle area of ​​the spring. At this time, the spring between the bolt head and the nut (bolt, the internal force of this section of the bolt is recorded as ) continues to be stretched, the spring in the middle of the nut-tensioner (bolt, the internal force of the bolt in this section is recorded as ) begins to be compressed, and the deformation of the two is the same, both At the same time, the spring constants of the two Consistent, therefore, satisfies:

[0085] ;

[0086] When the first target preload is reached After that, tighten the nut until the tensioner sensor reading drops to the second target preload. When the bolt is stretched, it is actually the internal force of the bolt in the nut-tensioner section that is decreasing.

[0087] ;

[0088] and It is the drop in the tensioner reading (and also the excess preload). In short, the drop in load on the tensioner sensor reading is equivalent to the increase in load on the bolt head-nut section.

[0089] In both operations, the bolt head-nut section is overstretched twice. Therefore, only half of the load increase in the bolt head-nut section is used to offset the preload consumed in the gap. The final target preload can be guaranteed . That is to satisfy

[0090] ;

[0091] Obviously, the excess value of the preload The stress cross-sectional area of ​​the bolt , Young's modulus , thread clearance , Clamping thickness of bolts In order to facilitate the application in engineering, it is easier to accept the percentage of preload. Therefore, the first target preload exceeds the percentage of the target preload value. The calculation formula is as follows:

[0092] ;

[0093] For bolt tension installation, the preload The value is usually 60%~90% of the bolt's ultimate yield load, and the value varies depending on the occasion.

[0094] ;

[0095] in, is the yield limit of the bolt.

[0096] ;

[0097] According to the calculation formula of P, the percentage by which the first target preload exceeds the target preload value It is related to the Young's modulus of the bolt, the amount of interface gap, the bolt clamping length, and the yield strength of the material. Due to the variability of actual conditions, these data are usually floating, so only an approximate range can be given. The value range of is calculated based on the sample data.

[0098] According to VDI 2230 Part I Appendix A5, the interface gap is related to the number of interfaces and roughness, and the recommended value is taken under normal circumstances. .

[0099] The Young's modulus of general steel materials is about , assuming the clamping thickness of the bolt is , bolt strength grade 10.9, then:

[0100] ;

[0101] In practical applications, the percentage by which the first target preload exceeds the target preload value The value is basically in the range of 2.5%~15%. a=1+P

[0102] A3. Use the second wrench 3 to rotate the nut 9 in the tightening direction. (At this time, the stud between the bolt head and the nut 9 is continuously stretched, and its stretching force increases and is greater than the first preset stretching force. The deformation of the stud between the internal threaded sleeve 1 and the nut 9 decreases, and the pressure detected by the pressure sensor 6 decreases.) When the pressure detected by the pressure sensor 6 decreases to the target preload force, stop rotating the nut 9.

[0103] A4. Rotate the internal threaded sleeve 1 in the loosening direction (at this time, the deformation of the bolt is reset, the tensile force generated is converted into pre-tightening force, and the gap between the thread surface of the nut 9 offsets the tensile force of the bolt between the bolt head and the nut 9, which is greater than the first preset tensile force).

[0104] A method for stretching and installing a threaded fastener 8, comprising the following steps:

[0105] S1, the internal thread sleeve 1 is threadedly connected with the threaded fastener 8;

[0106] S2, rotating the internal thread sleeve 1 to stretch the threaded fastener 8;

[0107] The tensile force of the bolt is detected during the process of rotating the internal threaded sleeve 1 in the tightening direction. When the tensile force reaches a first preset tensile force, the rotation of the internal threaded sleeve 1 is stopped. The first preset tensile force is greater than the target pre-tightening force of the threaded fastener 8.

[0108] The calculation formula of the first preset tensile force is as follows:

[0109] F1=F0×a;

[0110] Where F1 is the first preset tensile force, F0 is the target preload force, and the value range of a is 105%-120%.

[0111] The tensile force can be indirectly measured by the pressure sensor 6 mentioned above, and can also be directly measured by a tension sensor.

[0112] S3, rotating the nut 9 in the tightening direction. When the internal threaded sleeve 1 detects that the tensile force is the same as the target pre-tightening force of the threaded fastener 8, the rotation of the nut 9 is stopped and the process goes to step S4.

[0113] S4. Disassemble the internal threaded sleeve 1.

[0114] Beneficial effects:

[0115] First, by rotating the internal threaded sleeve 1, the internal threaded sleeve is driven to rotate electrically or mechanically to provide a tensile force, which reduces the overall manufacturing cost of the equipment and reduces the maintenance requirements. In addition, since the equipment structure is simpler, it is suitable for smaller projects and a wide range of industrial scenarios, thereby significantly reducing the cost of the unit installation station and improving its economy.

[0116] Second, compared with the existing hydraulic tensioners, the present invention tensions the bolt by rotating the internal threaded sleeve 1, thereby eliminating the hydraulic cylinder structure, reducing the size and weight of the equipment, and greatly improving the portability, making it more convenient to use in complex working conditions such as confined spaces, outdoors or at high altitudes. It can be carried and installed by a single operator, and is suitable for working environments that require flexible movement.

[0117] Third, the existing hydraulic stretching system requires external power supply and cannot be used in some outdoor or powerless environments. The present invention reduces the dependence on external power by adopting a built-in mobile power supply or mechanical drive. The built-in power supply can provide sufficient power for the electric drive system to ensure that the equipment can work normally even in places far away from the power supply, which is suitable for special environments such as outdoor operations or high-altitude installation.

[0118] Fourth, the calculation of the tensioning force of the hydraulic tensioner is greatly affected by external factors and is difficult to control accurately. The tensioning force is monitored and adjusted in real time by a high-precision pressure sensor 6 to ensure a higher preload accuracy, which is especially suitable for occasions requiring high preload accuracy.

[0119] Fifth, it is suitable for the installation of small-sized bolts and can adapt to the small-sized bolts (such as M6-M20) widely used in the market. By adjusting the design and driving method of the stretching device, it can better meet the installation requirements of small-sized bolts, and the operation steps are simplified, and the installation time is greatly shortened.

[0120] The proof that the torque of the internal threaded sleeve can be achieved is as follows:

[0121] Since the thread is a common metric thread, the calculation method for the torque required to achieve the tensile installation load of the bolt is the same as the preload-torque conversion formula for common metric bolts, which is:

[0122] ;

[0123] In the formula, is the assembly torque of the device of the present invention, is the bolt tension installation load, is the thread pitch diameter, is the thread angle (30° for metric threads), is the thread friction coefficient, is the thread pitch, is the equivalent friction diameter of the bolt head, is the friction coefficient of the bolt head. The axial load required for tensile installation can be obtained from Appendix A1 of VDI2230PartI.

[0124] For thread structure, the conversion ratio between torque and axial load is related to the thread friction coefficient. , friction coefficient of bolt head Negative correlation. When the axial load required for the tensile assembly remains unchanged, , The lower the torque, the less torque is required for assembly. However, in this device, the friction coefficient of the bolt head is We cannot control, but can only try to reduce the friction coefficient of thread engagement Therefore, the internal thread area of ​​the device must be sprayed with a self-lubricating coating or plating.

[0125] Taking the spraying of MoS2 self-lubricating coating (friction coefficient of about 0.11) on the internal thread area of ​​the device and the tension installation of 10.9-grade M12×1.75-meter bolts as an example, the assembly preload of the bolt when the comprehensive friction coefficient is 0.16 is obtained through the query of VDI2230PartI Appendix A1. , the other input parameters are: ( The values ​​are taken from the Mechanical Design Manual (Sixth Edition)), , , ( The values ​​are taken from the Mechanical Design Manual (Sixth Edition)), ( The value is taken from DIN7190, the usual friction coefficient of steel-steel material), then the assembly torque is: ;

[0126] Generally, the tightening torque of an ordinary manual torque wrench can reach 500Nm, and the tightening torque of a heavy-duty manual torque wrench can reach 1000Nm; the tightening torque of an ordinary electric brushless tightening gun can reach 800Nm, and the tightening torque of a heavy-duty electric tightening gun can reach 3000Nm. Obviously, The assembly torque is easily achievable for portable tightening tools.

[0127] Table 1 shows the torque input values ​​required for the tension installation of M6M20 metric bolts using the device proposed by the present invention.

[0128] Table 1 Torque input required for tension installation of M6~M20 metric bolts

[0129]

[0130] Note: The tensile load data in this table are from Appendix A1 of VDI2230 Part I, the friction coefficient of the bolt head is from the typical value provided by DIN7190, and the other values ​​are from the Mechanical Design Handbook (6th edition).

[0131] According to the calculation results in Table 1, the torque input requirements of bolts with specifications below M16 are all less than 500Nm, and the tensile assembly can be completed using an ordinary manual torque wrench; except for the 12.9-grade M20 bolts, the torque input requirements are all less than 800Nm, and ordinary electric brushless tightening guns can be used for assembly.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

[0133] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for stretching and installing a threaded fastener, characterized in that: To stretch mount a device using threaded fasteners: An internal threaded sleeve (1), wherein the internal threaded sleeve (1) is threadedly connected to a threaded fastener (8); A backing ring (4), the backing ring (4) is located between the internal thread sleeve (1) and the fastener (10), and a driving nut (9) is provided inside the backing ring (4) to rotate the driving assembly; A pressure sensor (6) is provided between the gasket (4) and the internal threaded sleeve (1), and the pressure sensor (6) is used to detect the pressure between the threaded sleeve (1) and the gasket (4); A plane bearing (5) is provided between the internal thread sleeve (1) and the pressure sensor (6); The internal thread sleeve (1) is installed on the inner side of the cylinder (7), and a baffle is fixedly provided at the lower end of the cylinder (7), and a through hole (701) corresponding to the threaded fastener (8) is opened on the baffle; The lower end of the internal threaded sleeve (1) is provided with a guide portion (102) matching the through hole (701), and the guide portion (102) is located on the inner side of the through hole (701); The threaded fastener (8) stretching installation device further comprises a first wrench (2) and a second wrench (3), wherein the first wrench (2) is used to drive the internal thread sleeve (1) to rotate; The driving component is a second wrench (3), and the second wrench (3) is used to drive the nut (9) to rotate; The threaded fastener stretch installation method includes the following steps: S1, the internal thread sleeve (1) is threadedly connected to the threaded fastener (8); S2, rotating the internal thread sleeve (1) to stretch the threaded fastener (8); During the process of rotating the internal threaded sleeve (1) in the tightening direction, the tensile force of the bolt is detected, and when the tensile force reaches a first preset tensile force, the rotation of the internal threaded sleeve (1) is stopped, wherein the first preset tensile force is greater than a target value of the pre-tightening force of the threaded fastener (8); S3, turn the nut (9) in the tightening direction; Rotate the nut (9) in the tightening direction until the indication of the stretching device drops to the target value of the pre-tightening force, stop rotating the nut (9) and proceed to step S4; S4, disassembling the internal thread sleeve (1); The upper end of the internal thread sleeve (1) is provided with a polygonal groove (101), and the side wall of the first wrench (2) is provided with a polygonal column (201) matching the polygonal groove (101), and the axis of the polygonal column (201) is vertically arranged perpendicular to the axis of the first wrench (2); The internal thread surface of the internal thread sleeve (1) is provided with a lubricating coating; The percentage by which the first preset tensile force exceeds the preload target value The calculation formula is as follows: ； The percentage by which the first preset tensile force exceeds the preload target value , is the Young's modulus of the bolt, is the interface gap, is the bolt clamping length, is the yield strength of the material.

2. A threaded fastener stretching installation method according to claim 1, characterized in that: A positioning groove (702) matching with the gasket ring (4) is formed on the lower end surface of the cylinder (7), and the gasket ring (4) is located on the inner side of the positioning groove (702).

3. A threaded fastener stretching installation method according to claim 1, characterized in that: The side wall of the gasket (4) is provided with an opening (401), and the second wrench (3) penetrates through the opening to be connected with the nut (9).

4. A threaded fastener stretching installation method according to claim 1, characterized in that: The cylinder (7) is provided with a controller, a power module and a buzzer. The pressure sensor (6) and the buzzer are electrically connected to the controller. The power module supplies power to the controller, the buzzer and the pressure sensor (6).

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