Bolt pretightening force detection system for electric power iron tower

Abstract

The invention relates to the field of mechanical sensors and measurement, and provides a bolt pre-tightening force detection system for an electric iron tower, which comprises a to-be-detected bolt, a fastening nut, a force measurement gasket, an iron tower connecting part and a control module, the force measuring gasket comprises a force bearing ring and a force measuring ring; the upper side of the bearing ring is closed, the lower side of the bearing ring is open, and a force measuring ring is nested in the open side of the bearing ring; the force measuring ring comprises an annular pad, a supporting block, a cantilever, an upper contact and a lower contact. The supporting block is arranged on the upper side of the annular pad; one side of the cantilever is connected with the supporting block, and the other side is suspended; the upper contact and the lower contact are coaxially or non-coaxially arranged on the upper side and the lower side of the cantilever respectively; the side, abutting against the force bearing ring, of the upper contact is a cambered surface, and the side, abutting against the annular pad, of the lower contact is a cambered surface. An elastic force measuring module is arranged in the middle of the lower contact. The upper contact and the lower contact which are used for transmitting pressure in the force measuring gasket are arranged in a cambered surface mode, so that friction torsion introduced when external force is applied to the bolt to be measured can be effectively avoided, and the measuring precision of the pre-tightening force is improved.

Description

Technical Field

[0001] The present invention relates to the field of mechanical sensors and measurements, and particularly to a bolt pre-tightening force detection system for power transmission towers. Background Art

[0002] Bolts are used to connect various components of power transmission towers. When detecting the structural strength or stability of power transmission towers, bolt pre-tightening force is usually used as an evaluation criterion. Most bolt pre-tightening force detection systems in the prior art measure bolt pre-tightening force by setting strain gauges inside the bolts or attaching strain gauges outside elastic gaskets. The method of setting strain gauges inside the bolts significantly reduces the service strength of the bolts because holes need to be drilled inside the bolts, making it not suitable for long-term use. The method of attaching strain gauges outside elastic gaskets has inaccurate measurement results because frictional torque is introduced during the tightening process of the bolts, and the measured pre-tightening force includes frictional torque. Therefore, how to improve the accuracy of bolt pre-tightening force detection while ensuring the service strength of bolts is a key research direction at present. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a bolt pre-tightening force detection system for power transmission towers, including: a bolt to be measured, a fastening nut, a force-measuring gasket, a tower connection part, and a control module; the force-measuring gasket is connected to the control module; The force-measuring gasket includes a load-bearing ring and a force-measuring ring; the upper side of the load-bearing ring is closed and the lower side is open, and the force-measuring ring is nested on one side of the opening; the force-measuring ring includes an annular pad, a support block, a cantilever, an upper contact head, and a lower contact head; the support block is arranged on the upper side of the annular pad; one side of the cantilever is connected to the support block and the other side is suspended; the upper contact head and the lower contact head are respectively arranged on the upper and lower sides of the cantilever coaxially or non-coaxially; the side of the upper contact head abutting against the load-bearing ring is an arc surface, and the side of the lower contact head abutting against the annular pad is an arc surface; an elastic force-measuring module is arranged in the middle of the lower contact head.

[0004] Optionally, the load-bearing ring includes an annular main body, a force-applying ring, and an annular cavity; the force-applying ring is arranged on the upper side of the annular main body, and the annular cavity is arranged on the lower side of the annular main body; the radial dimension of the force-applying ring is smaller than the radial dimension of the annular cavity, and the longitudinal projection of the force-applying ring is located in the middle of the longitudinal projection of the annular cavity.

[0005] Optionally, the support block is an arc-shaped block, and the number of support blocks is four. The four support blocks are evenly distributed in a circular pattern on the upper side of the annular pad. In the non-loaded state, the support blocks do not contact the annular body. The cantilever is an arc-shaped plate, the radial width of the cantilever is smaller than the radial width of the support block, and the thickness of the cantilever is smaller than the thickness of the support block. The number of the upper contact and the lower contact is four groups.

[0006] Optionally, the circumferences where the support blocks are located, the circumferences where the cantilevers are located, and the circumference where the annular pad is located are coaxially arranged.

[0007] Optionally, a plurality of connection holes are equidistantly arranged along the extending direction of the cantilever. The upper contact includes a hemispherical contact and an upper adapter block arranged in sequence from top to bottom, and the upper adapter block can be inserted into a specified connection hole. The lower contact includes a lower adapter block, an elastic force measuring module, and an arc-shaped contact arranged in sequence from top to bottom, and the lower adapter block can be inserted into a specified connection hole.

[0008] Optionally, the top surface of the hemispherical contact is higher than the top surface of the support block, and the height difference is less than the deformation limit of the elastic force measuring module.

[0009] Optionally, the elastic force measuring module adopts a force measuring grating at positions with strong electromagnetic radiation, and the elastic force measuring module adopts an elastic piezoresistive module at positions with weak electromagnetic radiation.

[0010] Optionally, the elastic modulus of the load-bearing ring is greater than the elastic modulus of the cantilever.

[0011] Optionally, when dealing with test bolts with different pre-tightening forces, the load-bearing ring with a different elastic modulus can be directly replaced, and the force measuring ring does not need to be replaced.

[0012] Compared with the prior art, the present invention has achieved the following technical effects: 1. By dividing the force measuring gasket into a load-bearing ring (main load-bearing component) and a force measuring ring (measuring component) with different elastic moduli, the load-bearing ring, as the main load-bearing structure, avoids opening holes in the bolt body to ensure that the bolt strength is not damaged. The upper and lower contacts for transmitting pressure in the force measuring gasket adopt an arc surface setting method, which can effectively avoid the frictional torque introduced by the test bolt when an external force is applied, reduce the additional load on the force measuring module, and improve the measurement accuracy of the pre-tightening force. When dealing with test bolts with different pre-tightening forces, the load-bearing ring with a different elastic modulus can be directly replaced, and the force measuring ring does not need to be replaced, improving the applicability of the detection system and saving costs.

[0013] 2. The elastic force measurement modules at four different positions can measure the eccentric load, facilitating the detection of the force changes at the connection parts of the iron tower at different positions. By measuring at multiple points, the uneven distribution of the bolt pre-tightening force can be identified, reflecting the local stress abnormality at the connection part of the iron tower and providing more comprehensive test data. One end of the cantilever is fixed to the support block, and the other end is suspended. The position of the contact is adjusted through the connection hole. The lever action of the cantilever converts the tiny deformation of the bearing ring into a significant deformation of the elastic force measurement module, improving the sensitivity and enabling the adjustment of the sensitivity.

[0014] 3. The force measurement grating is adopted in a strong electromagnetic radiation environment, and the elastic piezoresistive module is adopted in a weak electromagnetic environment, improving the anti-interference ability and meeting the requirements of flexible adaptation to various application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. is a schematic structural diagram of a bolt pre-tightening force detection system for a power transmission tower provided by an embodiment of the present invention; Figure 2 FIG. is a schematic structural diagram of a force measurement gasket in a bolt pre-tightening force detection system for a power transmission tower provided by an embodiment of the present invention; Figure 3 FIG. is a schematic structural diagram of a bearing ring in a bolt pre-tightening force detection system for a power transmission tower provided by an embodiment of the present invention; Figure 4 FIG. is a schematic structural diagram of a force measurement ring in a bolt pre-tightening force detection system for a power transmission tower provided by an embodiment of the present invention; Figure 5 FIG. is a schematic diagram of the internal details of a force measurement ring in a bolt pre-tightening force detection system for a power transmission tower provided by an embodiment of the present invention; Figure 6 FIG. is a schematic structural diagram of an upper contact and a lower contact in a bolt pre-tightening force detection system for a power transmission tower provided by an embodiment of the present invention; Figure 7 FIG. is a schematic wiring structure diagram of a force measurement ring in a bolt pre-tightening force detection system for a power transmission tower provided by an embodiment of the present invention; Figure 8 FIG. is a schematic diagram of the force on a bearing ring in a bolt pre-tightening force detection system for a power transmission tower provided by an embodiment of the present invention; Figure 9 FIG. is a schematic diagram of the force on a force measurement ring and the deformation diagram of the elastic force measurement module after being stressed in a bolt pre-tightening force detection system for a power transmission tower provided by an embodiment of the present invention.

[0016] The realization, functional features and advantages of the object of the present invention will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0018] As Figures 1-9 shown, an embodiment of the present invention provides a bolt pre-tightening force detection system for a power transmission tower, including: a bolt to be measured 1, a fastening nut 2, a force-measuring gasket 3, a tower connection part 4, and a control module (not shown); the force-measuring gasket 3 is connected to the control module; The force-measuring gasket 3 includes a load-bearing ring 31 and a force-measuring ring 32; the upper side of the load-bearing ring 31 is closed and the lower side is open, and the force-measuring ring 32 is nested on one side of the opening thereof; the force-measuring ring 32 includes an annular pad 321, a support block 322, a cantilever 323, an upper contact 324, and a lower contact 325; the support block 322 is arranged on the upper side of the annular pad 321; one side of the cantilever 323 is connected to the support block 322 and the other side is suspended; the upper contact 324 and the lower contact 325 are respectively arranged on the upper and lower sides of the cantilever 323 coaxially or non-coaxially; the side of the upper contact 324 abutting against the load-bearing ring 31 is an arc surface, and the side of the lower contact 325 abutting against the annular pad 321 is an arc surface. Since the arc surface contact allows for slight sliding, it avoids the transfer of lateral frictional torque during the bolt fastening process to the elastic force-measuring module, measures only the axial pre-tightening force, can significantly improve the accuracy, and can reduce the additional load of non-axial forces on the elastic force-measuring module and extend the service life of the sensor; an elastic force-measuring module 3252 is arranged in the middle of the lower contact 325.

[0019] In the above embodiment of the present invention, the force-measuring gasket is divided into a load-bearing ring (main load-bearing component) and a force-measuring ring (measuring component) with different elastic moduli. The load-bearing ring serves as the main load-bearing structure, which can avoid opening holes in the bolt body and ensure that the bolt strength is not damaged; moreover, by replacing the load-bearing ring with different elastic moduli, different pre-tightening force requirements can be adapted, and the force-measuring ring (including the sensor) can be reused, which can reduce costs.

[0020] Optionally, the bolt to be measured 1 passes through the tower connection part 4, and the bolt to be measured 1 is locked to the tower connection part 4 through the fastening nut 2; the force-measuring gasket 3 is sleeved on the outside of the bolt to be measured 1; the force-measuring gasket 3 is arranged between the nut of the bolt to be measured 1 and the tower connection part 4, or the force-measuring gasket 3 is arranged between the tower connection part 4 and the fastening nut 2.

[0021] Optionally, as Figure 3 shown, the load-bearing ring 31 includes an annular main body 311, a force-applying ring 312, and an annular cavity 313; the force-applying ring 312 is arranged on the upper side of the annular main body 311, and the annular cavity 313 is arranged on the lower side of the annular main body 311; the radial dimension of the force-applying ring 312 is smaller than the radial dimension of the annular cavity 313, and the longitudinal projection of the force-applying ring 312 is located in the middle of the longitudinal projection of the annular cavity 313.

[0022] Optionally, a wiring hole 314 penetrating through is provided on the side surface of the annular body 311.

[0023] Optionally, a limiting groove 315 is provided on the lower side of the annular body 311; a limiting block is provided on the side surface of the annular pad 321, and the size of the limiting block corresponds to the size of the limiting groove 315.

[0024] Optionally, as Figure 4 shown, the support block 322 is an arc-shaped block (exemplarily: each arc-shaped block can be regarded as one-ninth of the equally spaced segments along the circumferential direction of the annular block), the number of the support blocks 322 is four, and the four support blocks 322 are evenly distributed on the upper side of the annular pad 321 in a circumferential manner; in a non-loaded state, the support block 322 does not contact the annular body 311; the cantilever 323 is an arc-shaped plate (exemplarily: each arc-shaped plate can be regarded as one-eighth of the equally spaced segments along the circumferential direction of the annular plate), the radial width of the cantilever 323 is smaller than the radial width of the support block 322, and the thickness of the cantilever 323 is smaller than the thickness of the support block 322; the number of the upper contacts 324 and the lower contacts 325 is four groups.

[0025] Optionally, the circumferences where the support blocks 322 are located (the circumferences are located in the middle of the radial distribution positions of the support blocks 322), the circumferences where the cantilevers 323 are located (the circumferences are located in the middle of the radial distribution positions of the cantilevers 323), and the circumference where the annular pad 321 is located (the circumference is located in the middle of the radial distribution position of the annular pad 321) are coaxially arranged.

[0026] Optionally, as Figure 6As shown in the figure, a plurality of connection holes are equidistantly arranged along the extension direction of the cantilever 323; the upper contact 324 includes a hemispherical contact 3241 and an upper adapter block 3242 arranged in sequence from top to bottom, and the upper adapter block 3242 can be inserted into a specified connection hole; the lower contact 325 includes a lower adapter block 3251, an elastic force measuring module 3252 and an arc contact 3253 arranged in sequence from top to bottom, and the lower adapter block 3251 can be inserted into a specified connection hole. By adjusting the positions of the upper contact 324 and the lower contact 325, the sensitivity of the elastic force measuring module 3252 is adjusted. For example, when the lower contact 325 is arranged at one end of the cantilever 323 away from the support block 322, and the upper contact 324 is arranged in the connection holes at different positions, when the downward displacements of the upper contact 324 at each position are the same, the closer the upper contact 324 is arranged to the support block 322, the greater the downward displacement of the lower contact 325, the greater the deformation of the elastic force measuring module 3252, and the lever action of the cantilever converts the tiny deformation of the load-bearing ring into a significant deformation of the elastic force measuring module, achieving a mechanical amplification effect, and the corresponding detection sensitivity is higher. Moreover, by adjusting the positions of the contacts on the cantilever (different connection holes) and changing the length of the force arm, the sensitivity can be adjusted to adapt to different range requirements.

[0027] Optionally, the elastic force measuring module 3252 is an elastic cylinder with a hole in the middle, and a force measuring grating (fiber grating) with different reflection wavelengths is arranged at the hole position. When the force measuring grating senses pressure, its reflection wavelength will change, thereby realizing the measurement of pressure. Exemplarily, four gratings with different reflection wavelengths are arranged on a single optical fiber, and the single optical fiber sequentially passes through the four elastic force measuring modules 3252, and the force measuring grating is located at the hole position of the elastic cylinder, thereby realizing the measurement and differentiation of pressures at different positions.

[0028] Optionally, the elastic force measuring module 3252 is an elastic piezoresistive module. When the elastic piezoresistive module senses pressure, its resistance changes, thereby realizing the measurement of pressure. The measurement and differentiation of pressures at different positions are realized through different wiring terminals.

[0029] In the present invention, the four elastic force measuring modules 3252 are equidistantly distributed along the circumference of the annular pad, and each group corresponds to a cantilever-contact unit. By identifying the uneven distribution of the bolt pre-tightening force through multi-point measurement, the local stress abnormality of the tower connection part can be reflected, and more comprehensive structural health data can be provided. Moreover, the failure of a single point does not affect the overall system function, improving the reliability.

[0030] Optionally, the control module includes a power supply (such as a battery, an external power supply, a solar or wind energy storage device, etc.), a processing module, a signal transmitting and receiving part (the transmission and reception of optical signals or electrical signals), and a signal transmission module (wired or wireless transmission); the control module can send the detection structure to an external device (such as a mobile device, an external processor, etc.).

[0031] Optionally, at positions with strong electromagnetic radiation, the elastic force measurement module 3252 uses a force measurement grating, and at positions with weak electromagnetic radiation, the elastic force measurement module 3252 uses an elastic piezoresistive module. By this means, the anti-interference ability can be improved. Fiber Bragg gratings are immune to electromagnetic interference and can be applied to strong electromagnetic scenarios such as substations; piezoresistive modules have low costs and can be applied to ordinary environments. Select the corresponding sensor type according to the actual working conditions and flexibly adapt to the applicable scenarios.

[0032] Optionally, as Figure 5 shown (the dashed part), the top surface of the hemispherical contact 3241 is higher than the top surface of the support block 322, and this height difference is less than the deformation limit of the elastic force measurement module 3252. At this time, the support block 322 can be used as a limiting device to limit the downward displacement distance of the top of the annular cavity 313 and prevent damage to the elastic force measurement module 3252.

[0033] Optionally, wire grooves are provided on the inner and outer sides of the support block 322, and these wire grooves can be used for the laying and fixing of cables.

[0034] Optionally, the load-bearing ring 31 is integrally formed; the annular pad 321, the support block 322, and the cantilever 323 are integrally formed. The integrally formed setting method can increase the overall strength of the system.

[0035] Optionally, the elastic modulus of the load-bearing ring 31 is greater than the elastic modulus of the cantilever 323; the elastic modulus of the load-bearing ring 31 is less than the elastic modulus of the support block 322. As the main load-bearing structure of the bolt to be measured, setting the elastic modulus of the load-bearing ring 31 to be greater than the elastic modulus of the cantilever 323 can, on the one hand, improve the load-bearing strength, and on the other hand, reduce the load-bearing strength of the cantilever so that it only bears the measurement function; setting the elastic modulus of the load-bearing ring 31 to be less than the elastic modulus of the support block 322 can further improve the protection performance after overload and prevent the cantilever from being damaged due to overload and losing its reset function.

[0036] Optionally, when dealing with bolts to be measured with different pre-tightening forces, the load-bearing ring 31 with different elastic moduli can be directly replaced, and the force measurement ring 32 does not need to be replaced.

[0037] Optionally, the materials of the load-bearing ring 31, the annular pad 321, the support block 322, the cantilever 323, the upper contact 324, the lower adapter block 3251, and the arc-shaped contact 3253 are alloy steel, carbon steel, etc.

[0038] The working principle of the bolt pre-tightening force detection system for power transmission towers: Install the force measurement gasket 3 at the tower connection part 4 at the specified position of the power transmission tower, measure the pre-tightening force through the force measurement gasket 3, and transmit the measured pre-tightening force data through the control module.

[0039] When the force-measuring gasket is working, when the force-applying ring 312 bears the tightening force applied by the bolt to be measured, the force-applying ring 312 will drive the annular main body 311 to deform. At this time, the top of the annular cavity 313 will displace downward to apply a downward force on the upper contact 324, and transmit it to the lower contact 325 through the cantilever 323. Since the lower contact 325 abuts against the annular pad 321, the lower adapter block 3251 and the arc-shaped contact 3253 will apply an extrusion force on the middle elastic force-measuring module 3252, and sense the pressure change through the deformation of the elastic force-measuring module 3252. As Figure 8 shown (left), during the tightening process of the bolt to be measured, a downward tightening force and a torque caused by friction will be applied to the force-measuring gasket 3. Since the side of the upper contact 324 abutting against the bearing ring 31 is an arc surface, and the side of the lower contact 325 abutting against the annular pad 321 is an arc surface, the deformation sensed by the elastic force-measuring module 3252 at this time is only the deformation caused by the tightening force, and will not sense the deformation caused by the torque. While reducing the cantilever load, the measurement accuracy of the tightening force is further improved. The elastic force-measuring modules 3252 at four different positions can realize the measurement of the off-axis load force, which is convenient for detecting the force changes at the connection parts of the iron tower at different positions.

[0040] In summary, through the optimization of the mechanical structure, such as split gaskets, arc-shaped contacts, cantilever levers and sensing strategies (multi-point measurement, environmental adaptation), the present invention solves the contradiction between strength and accuracy in traditional pre-tightening force detection. It not only ensures the structural integrity of the bolt, but also significantly improves the measurement accuracy and practicality by eliminating torque interference and off-axis load detection.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. Bolt preload detection system for power towers, including: Bolts to be tested, fastening nuts, force-measuring washers, tower connection parts and control modules; characterized in that the force-measuring washers are connected to the control modules; The force measuring gasket includes a load-bearing ring and a force measuring ring; the upper side of the load-bearing ring is closed and the lower side is open, and the force measuring ring is nested on one side of the opening; the force measuring ring includes an annular pad, a support block, a cantilever, an upper contact and a lower contact; the support block is arranged on the upper side of the annular pad; one side of the cantilever is connected to the support block, and the other side is suspended; the upper contact and the lower contact are coaxially or non-coaxially arranged on the upper and lower sides of the cantilever; the side of the upper contact abutting the load-bearing ring is an arc surface, and the side of the lower contact abutting the annular pad is an arc surface; an elastic force measuring module is arranged in the middle of the lower contact.

2. The detection system according to claim 1, characterized in that: in, The load-bearing ring includes an annular body, a force ring and an annular cavity; the force ring is arranged on the upper side of the annular body, and the annular cavity is arranged on the lower side of the annular body; the radial dimension of the force ring is smaller than the radial dimension of the annular cavity, and the longitudinal projection of the force ring is located in the middle of the longitudinal projection of the annular cavity.

3. The detection system according to claim 1, characterized in that: in, The support block is an arc-shaped block, and there are four support blocks in number. The four support blocks are equidistantly distributed on the upper side of the annular pad in a circumferential manner; in a non-stressed state, the support block does not contact the annular body; the cantilever is an arc-shaped plate, the radial width of the cantilever is smaller than the radial width of the support block, and the thickness of the cantilever is smaller than the thickness of the support block; the number of the upper contacts and the lower contacts is four groups.

4. The detection system according to claim 3, characterized in that: in, The circumference of the support block, the circumference of the cantilever and the circumference of the annular pad are coaxially arranged.

5. The detection system according to claim 3, characterized in that: in, A plurality of connection holes are equidistantly arranged along the extension direction of the cantilever; the upper contact comprises a hemispherical contact and an upper adapter block which are arranged in sequence from top to bottom, and the upper adapter block can be inserted into a designated connection hole; the lower contact comprises a lower adapter block, an elastic force measuring module and an arc contact which are arranged in sequence from top to bottom, and the lower adapter block can be inserted into the designated connection hole.

6. The detection system according to claim 5, characterized in that: in, The top surface of the hemispherical contact is higher than the top surface of the supporting block, and the height difference is smaller than the deformation limit of the elastic force measuring module.

7. The detection system according to claim 1, characterized in that: in, The elastic force measuring module adopts a force measuring grating at a location with strong electromagnetic radiation, and adopts an elastic piezoresistive module at a location with weak electromagnetic radiation.

8. The detection system according to claim 1, characterized in that: in, The elastic modulus of the load-bearing ring is greater than the elastic modulus of the cantilever.

9. The detection system according to claim 1, characterized in that: in, When dealing with bolts to be tested with different pre-tightening forces, the load-bearing rings with different elastic moduli can be directly replaced, and the force measuring ring does not need to be replaced.

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