The utility model relates to the technical field of sensors, especially a strain-type thread preload force sensor. In most cases, uneven or insufficient bolt load is the cause of bolt locking function failure and loosening, and accidents such as loosening and leaking of structural components can occur. The common method used in the current common bolt assembly process is to overload the gasket and use the rebound deformation of the gasket to compensate for the subsequent bolt slack, thus preventing the loosening of the mechanism parts and reinforcing the threaded coupling with thread adhesive. However, over time, fatigue, corrosion, and weathering of the gasket can cause the bolt preload to decrease, resulting in a loss of locking function. In operating equipment, the load on the bolts will constantly change, which may lead to fatigue fracture of the bolts, or thread adhesive falling off, loosening of the threads and so on. For example, in critical (steel) structures such as differential wind turbines, highly loaded bolts need to be inspected and re-tightened, which is very expensive and even requires periodic replacement.
In view of the above technical deficiencies, an object of the utility model is to provide a strain-type thread preload sensor, which can be used as a gasket for a long period of time, and the preload can be directly monitored when locking bolts, and the dynamic and static preload changes of the equipment can be monitored in real time. In order to solve the above technical problems, the utility model adopts the following technical solution: the utility model provides a strain-type thread preload force sensor, including an annular elastomer, one end of the annular elastomer is provided with a protruding flange, the flange and the elastomer are provided with a second annular groove at the connection place, and the elastomer is provided with a first annular groove on the surface far away from the flange; a plurality of strain gauges are provided in the first annular groove of the thread preload force sensor along the circumferential direction evenly distributed strain gauges; and the strain gauges are attached to an inner peripheral wall of the first annular groove. The number of strain gauges is eight, with two in series. The perpendicular distance between the outer and inner walls of the second annular groove of the threaded preload sensor and the axis of the elastomer decreases in the direction close to the first annular groove; the bottom of the second annular groove of the threaded preload sensor is a circular arc surface. Two threaded holes are symmetrically provided on both sides of the threaded holes; the threaded holes of the threaded preload force sensor extend into the first annular groove and are connected to the first annular groove; the threaded holes of the threaded preload force sensor are blind holes. The surface of the thread preload force sensor elastomer away from the flange is also provided with a cover plate.
The advantages of the utility model are: the sensor of the utility model can be placed between the bolt and the mechanism as a spacer, which can confirm the preload force in real time during the tightening of the bolt, and monitor the change of the dynamic and static preload force of the equipment at a later stage; wherein eight strain gauges are connected in series, and the two series-connected strain gauges are connected with a bridge, which exactly constitutes the four strains required by the Wheatstone bridge. In addition, the first annular groove and the second annular groove interact with each other during bolt preloading, increasing the strain and improving the sensing effect of the strain gauges.
Room B612-59, No. 91 Hanjiang West Road, Xinqiao Street, Xinbei District, Changzhou City, Jiangsu Province, China