This article belongs to the field of bolt pre-tightening force measurement, and specifically relates to a wireless thread pre-tightening force sensor. The bolt preload is the force along the bolt axis between the bolt and the connector during the bolt tightening process. During the operation of industrial equipment, the vibration of the equipment and other reasons may loosen the bolts, thereby causing the connecting parts to fall off, resulting in safety accidents. Therefore, the measurement of bolt preload is essential for the safe and reliable operation of industrial equipment. Currently, torque wrenches and ring sensors are mainly used to measure bolt preload. Because the cable may be entangled or even broken during the continuous rotation, it has great limitations in connecting parts that require continuous rotation, such as the blades of wind turbines.

The object of the present invention is to provide a wireless thread preload force sensor, which can be used on a continuously rotating coupling. No signal transmission cable is required between the sensor and the display instrument, and the preload signal can be transmitted remotely. The sensor can be used to connect parts with a large number of bolts, which are easy to loosen and can rotate continuously, such as wind turbine blades. In order to achieve the above purpose, technicians adopt the following technical solution: a wireless thread pre-tightening force sensor, including a spoke elastic body and an inner cavity, the inner cavity is located under the elastic body, and the inner cavity is provided with a signal processing circuit and a wireless communication device. The threaded preload sensor is installed between the gasket of the bolt and the connecting piece; the screw holes on the threaded preload sensor bolt, gasket, sensor and coupling are coaxial, the top of the sensor is in contact with the bottom of the gasket, and the bottom of the sensor is in contact with the coupling Piece top contact.

There are eight symmetrical circular holes on the spoke elastic body of the threaded preload sensor, and the area between two adjacent circular holes constitutes a strain beam, and a metal foil strain gauge is pasted on both sides of each strain beam to form a symmetry Huygens Bridge structure. The radio communication module is fixed on the signal processing circuit board with a single row of pins. The communication antenna is drawn out through the antenna hole on the sensor shell. After the antenna is drawn out, the inner and outer sides of the antenna hole are waterproof and sealed with waterproof glue; The rechargeable lithium battery of the sensor is installed in the inner cavity on the back of the signal processing circuit board, and the charging interface of the lithium battery is connected with the waterproof charging interface on the sensor shell. The thread pre-tightening force sensor signal processing circuit board also has a Huygens bridge signal output circuit, a single-chip microcomputer circuit, a wireless communication circuit and a power supply circuit.

To sum up, this method can realize the real-time and accurate detection of bolt pre-tightening force, because the lithium battery power supply, signal processing and wireless transmission circuit are added to the sensor, and the power supply cable and signal transmission are no longer needed between the sensor and the display instrument. The cable solves the problem of cable entanglement and breakage when the sensor is continuously rotated with the installation parts, so the above method can be installed on the construction with a large number of bolts, such as wind turbine blades, which are easy to loosen and can be rotated continuously. At the same time, the wireless communication mode can choose different communication frequencies and communication protocols according to the actual working conditions, and the distance between the display instrument and the sensor can be longer, reducing the difficulty of on-site wiring and construction costs.