Bolt pre-tightening force monitoring device
The bolt preload monitoring device, which integrates strain gauges and gaskets, solves the problem of unstable bolt preload monitoring in existing technologies, and enables real-time monitoring and safety assurance in high-risk environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHINA RAILWAY ENGINEERING EQUIPMENT GROUP CO LTD
- Filing Date
- 2025-08-12
- Publication Date
- 2026-07-24
AI Technical Summary
In existing technologies, bolt preload monitoring is difficult to achieve in real time and stably in high-risk or narrow locations, and the sensors are easily damaged, leading to safety hazards.
The design integrates strain gauges and gaskets, with grooves completely enclosing the strain gauges to isolate them from external mechanical impacts and environmental corrosion. Combined with strain acquisition devices and controllers, it enables real-time monitoring of preload and avoids manual intervention.
Real-time monitoring of bolt preload was achieved, improving the stability of the device in high-risk environments, preventing accidents caused by unstable connections, and ensuring the safety of staff.
Smart Images
Figure CN224552592U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of bolt preload technology, and in particular to a bolt preload monitoring device. Background Technology
[0002] This section is intended to provide background or context for the embodiments of the present invention set forth in the claims. The description herein is not an admission that it is prior art simply because it is included in this section.
[0003] Bolted connections are a critical connection method in fields such as machinery, chemical engineering, and transportation, and their reliability directly depends on axial preload. Insufficient or loose preload can lead to bolt loosening, fatigue fracture, or even safety accidents. Especially in complex equipment such as tunnel boring machines, a large number of bolts are located in high-risk or narrow positions, making manual point-to-point monitoring of preload inefficient and extremely risky.
[0004] Currently, preload monitoring mainly relies on two types of technologies. Manual testing tools, such as torque wrenches, require close-range operation, making it impossible to monitor dynamic changes in preload in real time, and high-risk locations are difficult to cover. External sensor attachment methods involve adding sensors or microprocessor chips to the outside of the bolt for monitoring. However, the sensor is not integrated with the bolt body; for example, externally attached strain gauges are susceptible to damage from mechanical impacts. Exposed sensor wiring is prone to failure in humid or dusty environments. Furthermore, the non-integrated design requires modifications to the bolt structure or additional fixing devices, making it difficult to adapt to standard bolts. Utility Model Content
[0005] This utility model provides a bolt preload monitoring device. Through an integrated design of strain gauges and washers, it ensures long-term stable operation in vibrating and humid environments. By converting deformation into electrical signals, and then into corresponding bolt preload values, it achieves real-time monitoring of preload changes. This promptly prevents accidents caused by unstable connections due to bolt loosening or failure, effectively protecting the lives of workers. The device includes: a bolt body 1, a nut 2, a washer 3, a strain gauge 4, a strain acquisition device 5, and a controller 6.
[0006] The outer wall of the bolt body 1 is provided with a threaded structure;
[0007] The nut 2 matches the thread structure of the bolt body 1, and the bolt body 1 passes through the nut 2;
[0008] The pressure-bearing surface of the gasket 3 is provided with a groove for accommodating the strain gauge 4, and the gasket 3 and the strain gauge 4 form an integrated structure.
[0009] The strain acquisition device 5 is used to acquire the deformation of the strain gauge 4 and convert the deformation into a deformation electrical signal, which is then output to the controller 6.
[0010] The controller 6 is used to convert the deformation electrical signal transmitted by the strain acquisition device into the corresponding bolt preload value through a conversion circuit.
[0011] In this embodiment of the invention, the pressure-bearing surface of the gasket in the bolt preload monitoring device has a groove to accommodate the strain gauge, forming an integrated structure in which the strain gauge is completely enclosed within the groove. This design directly isolates the sensor from external mechanical impacts, dust, and humid environments, enhancing the long-term stability of the device under high-risk or corrosive conditions such as tunnel boring machines. The groove acts as a physical protective layer, ensuring that the strain gauge only senses the pure deformation signal after the gasket is compressed, avoiding false measurements or signal drift. The strain acquisition device is directly connected to the strain gauge, converting the deformation into a deformation electrical signal in real time. The signal conversion is achieved through the built-in conversion circuit of the controller, converting the deformation electrical signal into a bolt preload value. This avoids manual intervention, enabling real-time monitoring of preload changes and timely prevention of accidents caused by unstable connection of connected parts due to bolt loosening or failure, effectively protecting the lives of workers. Attached Figure Description
[0012] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:
[0013] Figure 1 This is a schematic diagram of the bolt preload monitoring device in an embodiment of this utility model;
[0014] Figure 2 This is an enlarged schematic diagram of the bolt preload monitoring device in an embodiment of this utility model;
[0015] Figure 3 This is a schematic diagram of the gasket in an embodiment of the present invention. Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the embodiments of this utility model will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments of this utility model and their descriptions are used to explain this utility model, but are not intended to limit this utility model.
[0017] Figure 1 This is a schematic diagram of the bolt preload monitoring device in an embodiment of this utility model. Figure 2This is an enlarged schematic diagram of the bolt preload monitoring device in an embodiment of the present invention. The device includes: a bolt body 1, a nut 2, a washer 3, a strain gauge 4, a strain acquisition device 5, and a controller 6; wherein,
[0018] The outer wall of the bolt body 1 is provided with a threaded structure;
[0019] The nut 2 matches the thread structure of the bolt body 1, and the bolt body 1 passes through the nut 2;
[0020] The pressure-bearing surface of the gasket 3 is provided with a groove for accommodating the strain gauge 4, and the gasket 3 and the strain gauge form an integrated structure.
[0021] The strain acquisition device 5 is used to acquire the deformation of the strain gauge 4 and convert the deformation into a deformation electrical signal, which is then output to the controller 6.
[0022] The controller 6 is used to convert the deformation electrical signal transmitted by the acquired strain gauge into the corresponding bolt preload value through a conversion circuit.
[0023] In one embodiment, the sidewall of the gasket 3 is provided with a lead wire groove, which is connected to the groove and is used to lay the lead wire.
[0024] Figure 3 This is a schematic diagram of the gasket in an embodiment of the present invention. In a specific embodiment, the groove 301 is formed in the central region of the pressure-bearing surface of the gasket 3, and its depth is less than the thickness of the gasket 3; the lead wire groove 302 is a narrow channel penetrating the sidewall of the gasket 3, the lead wire groove 302 communicates with the groove 301, and extends to the outer edge of the gasket 3. The position of the groove ensures that the strain gauge 4 directly senses the pressure deformation; the lead wire groove provides a physical wiring path to avoid the lead wire 7 being damaged by pressure.
[0025] In one embodiment, the strain gauge 4 is fixed to the groove by an adhesive, and the groove is filled with insulating sealant to cover the strain gauge 4. The adhesive bonding integrates the strain gauge and the gasket, preventing displacement; the sealant protects against environmental corrosion and is suitable for use in damp conditions of tunnel boring machines.
[0026] In one embodiment, the strain gauge 4 within the groove is attached to the surface of the bolt body 1 and connected to the strain acquisition device 5 via a lead wire 7. This attachment method ensures that the strain gauge and the stud deform synchronously. When the hydraulic tensioner applies tension, the double-ended stud undergoes axial deformation. The strain acquisition device directly acquires the deformation electrical signal from the strain gauge, achieving indirect monitoring of the preload. Preload monitoring is achieved through the physical deformation of the strain gauge, without damaging the bolt body, making it safe and efficient.
[0027] In one embodiment, the controller 6 includes:
[0028] The display unit is used to display the bolt preload value in real time.
[0029] An alarm indicator connected to the display unit is used to drive different colored indicator lights to illuminate based on the bolt preload value.
[0030] In one embodiment, the alarm indicator includes: a threshold comparison circuit and a multi-color LED light group; wherein,
[0031] The input terminal of the threshold comparison circuit is electrically connected to the output terminal of the conversion circuit; the threshold comparison circuit is used to receive the voltage signal corresponding to the bolt preload value.
[0032] A multi-color LED indicator group includes a green LED indicator, a yellow LED indicator, and a red LED indicator connected in parallel. The cathode of each LED indicator is connected to the output terminal of the threshold comparison circuit through a driving transistor.
[0033] Specifically, when the voltage signal is within a first preset voltage range, the green LED indicator is turned on and remains constantly lit; when the voltage signal is within a second preset voltage range, the yellow LED indicator is turned on and remains constantly lit; and when the voltage signal is within a third preset voltage range, the red LED indicator is turned on and remains constantly lit or flashes intermittently.
[0034] In a specific embodiment, the controller is equipped with a display screen that can display the preload value in real time. In the controller's threshold comparison circuit, assuming the reference voltage is V1, the voltage signal corresponding to the bolt preload value is V. A voltage signal V corresponding to the bolt preload value within the range of 0.8V1 to V1 is normal, and the indicator light will be solid green. If V is between 0.5V1 and 0.8V1, the preload decreases significantly, indicating that the bolt is gradually loosening and the inspection frequency needs to be increased; in this case, the indicator light will be solid yellow. If V is below 0.5V1, it indicates that the bolt is severely loose and further inspection is needed; in this case, the indicator light will be solid red. If V is greater than V1, it indicates that the preload is too high, which will affect the bolt's lifespan; the preload setting should be checked promptly, and the indicator light will flash red.
[0035] In this embodiment of the invention, the pressure-bearing surface of the gasket in the bolt preload monitoring device has a groove to accommodate the strain gauge, forming an integrated structure in which the strain gauge is completely enclosed within the groove. This design directly isolates the sensor from external mechanical impacts, dust, and humid environments, enhancing the long-term stability of the device under high-risk or corrosive conditions such as tunnel boring machines. The groove acts as a physical protective layer, ensuring that the strain gauge only senses the pure deformation signal after the gasket is compressed, avoiding false measurements or signal drift. The strain acquisition device is directly connected to the strain gauge, converting the deformation into a deformation electrical signal in real time. The signal conversion is achieved through the built-in conversion circuit of the controller, converting the deformation electrical signal into a bolt preload value. This avoids manual intervention, enabling real-time monitoring of preload changes and timely prevention of accidents caused by unstable connection of connected parts due to bolt loosening or failure, effectively protecting the lives of workers.
[0036] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above descriptions are merely specific embodiments of this utility model and are not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.
Claims
1. A bolt preload monitoring device, characterized in that, include: Bolt body (1), nut (2), washer (3), strain gauge (4), strain acquisition device (5), and controller (6); among which, The bolt body (1) has a threaded structure on its outer wall; The nut (2) matches the thread structure of the bolt body (1), and the bolt body (1) passes through the nut (2); The pressure-bearing surface of the gasket (3) is provided with a groove for accommodating the strain gauge (4), and the gasket (3) and the strain gauge (4) form an integrated structure; The strain acquisition device (5) is used to acquire the deformation of the strain gauge (4) and convert the deformation into a deformation electrical signal and output it to the controller (6); The controller (6) is used to convert the deformation electrical signal transmitted by the strain acquisition device (5) into the corresponding bolt preload value through the conversion circuit.
2. The bolt preload monitoring device as described in claim 1, characterized in that, The side wall of the gasket (3) is provided with a lead wire groove, which is connected to the groove. The lead wire groove is used to lay the lead wire (7).
3. The bolt preload monitoring device as described in claim 2, characterized in that, The strain gauge (4) in the groove is attached to the surface of the bolt body (1) and connected to the strain acquisition device (5) through the lead wire (7).
4. The bolt preload monitoring device as described in claim 1, characterized in that, The strain gauge (4) is fixed in the groove by an adhesive, and the groove is filled with insulating sealant to cover the strain gauge (4).
5. The bolt preload monitoring device as described in claim 1, characterized in that, The controller (6) includes: The display unit is used to display the bolt preload value in real time. An alarm indicator connected to the display unit is used to drive different colored indicator lights to illuminate based on the bolt preload value.
6. The bolt preload monitoring device as described in claim 5, characterized in that, The alarm indicator includes: a threshold comparison circuit and a multi-color LED light group; wherein... The input terminal of the threshold comparison circuit is electrically connected to the output terminal of the conversion circuit; the threshold comparison circuit is used to receive the voltage signal corresponding to the bolt preload value. The multi-color LED indicator group includes a green LED indicator, a yellow LED indicator, and a red LED indicator connected in parallel. The cathode of each LED indicator is connected to the output terminal of the threshold comparison circuit through a driving transistor.