Development of application technology of high strength bolts for electric spanners and steel structures in China. In the application of high-strength bolts in steel structures, the most important thing is how to ensure that the tightening axial force of all high-strength bolt connection pairs is designed as far as possible (other metal structures have similar or even higher requirements). This is also our goal to pursue engineers and technicians in transportation, construction and other industries. Excessive axial force (i.e., over-torsion) will lead to bolt fracture or delay fracture for a period of time; too low axial force (i.e., under-torsion) will bring hidden dangers to structural safety.

　　一代電動扳手

　　China's First Generation Electric Spanner我國一代電動扳手以電機的比較大輸出扭矩為比較終輸出扭矩，通過齒輪傳動減速，也就是說，一代電動扳手只能提供比較大的輸出扭矩。在1970年代和1960年代,由于相對落后的生產技術在的高強度螺栓,高強度螺栓的聯合對同一批次不能提供按照保證轉矩系數,所以旋轉角的方法只能用于高強度螺栓。當時一代電動扳手的輸出扭矩不夠大，無法滿足高強度螺栓聯軸器的要求，只能使用氣動沖擊扳手。該方法施工過程復雜，精度低。

　　The first generation of electric wrenches in China takes the maximum output torque of the motor as the final output torque, and reduces the speed by gear transmission. That is to say, the first generation of electric wrenches can only provide the maximum output torque. In the 1970s and 1960s, due to the relatively backward production technology of high strength bolts in China, the combination of high strength bolts can not provide the same batch according to the guaranteed torque coefficient, so the rotation angle method can only be used for high strength bolts. At that time, the output torque of the first generation of electric wrenches was not large enough to meet the requirements of high strength bolt coupling, only pneumatic impact wrench was used. This method has complex construction process and low precision.

　　第二代、第三代電動扳手

　　Second and Third Generation Electric Spanners20世紀80年代，我國高強度螺栓連接的生產技術有了很大的提高，高強度螺栓生產廠家可以提供連接的扭矩系數，這為扭矩法應用于高強度螺栓創(chuàng)造了必要的條件。但是，當時還沒有固定扭矩電動扳手。為了建設九江長江大橋，有關部門設立了開發(fā)第二代定扭矩電動扳手的項目。從上面的情況下,電動扳手的第三代精確的扭矩,扭矩輸出可以設置,顯示和記錄存儲、扭曲的過程中還可以轉矩系數太小或太大高強度螺栓聯接,從而大大提高高強度螺栓聯接的精度;也大大簡化了施工過程。采用第三代電動扳手擰緊高強螺栓聯接副，使我國高強螺栓施工技術向前邁出了一大步，達到了世界水平。2014年11月，參加第三代電動扳手評估會的對其優(yōu)異表現給予了肯定。

　　In the 1980s, the production technology of high-strength bolt connections in China has been greatly improved. The manufacturers of high-strength bolts can provide the torque coefficient of connections, which creates the necessary conditions for the application of the torque method to high-strength bolts. However, there was no fixed torque electric wrench in China at that time. In order to construct the Jiujiang Yangtze River Bridge, the relevant state departments have set up a project to develop the second generation of fixed torque electric wrenches. From the above situation, the third generation of accurate torque and torque output of electric wrench can be set, display and record storage, distortion process can also eliminate the torque coefficient too small or too large high-strength bolt connection, thus greatly improving the accuracy of high-strength bolt connection; and greatly simplify the construction process. Using the third generation electric wrench to tighten the high-strength bolt connection pair, the construction technology of high-strength bolt in our country has taken a big step forward and reached the world leading level. In November 2014, experts who participated in the Third Generation Electric Spanner Assessment Meeting affirmed its outstanding performance.

　　第三代第四代電動扳手

　　Third Generation and Fourth Generation Electric Spanners雖然第三代電動扳手的性能準確的輸出扭矩,高強度螺栓連接副的收緊軸向力也是影響離散的螺栓連接副扭矩系數,所以第三代電動扳手的目的不能實現準確控制收緊螺栓連接副的軸向力。在成功開發(fā)第三代電動扳手的基礎上，聯合開發(fā)了第四代電動扳手。這一代電動扳手不僅能精確控制輸出扭矩，還能設置、顯示和記錄高強度螺栓聯軸器的擰緊軸力。只要用戶在啟動前輸入螺桿聯軸器所需的擰緊軸力，第四代電動扳手運行后即可自動實現所需的擰緊軸力(電流誤差為5%)。這種電動扳手暫時稱為預緊力可控的電動扳手。
                                 

　　Although the performance of the third generation electric wrench can accurately output the torque, the tightening axial force of the high strength bolt connection pair also affects the discrete torque coefficient of the bolt connection pair, so the purpose of the third generation electric wrench can not accurately control the tightening axial force of the bolt connection pair. Based on the successful development of the third generation electric wrench, the fourth generation electric wrench is developed jointly. This generation of electric wrenches can not only accurately control the output torque, but also set, display and record the tightening force of high strength bolt coupling. As long as the user inputs the required tightening force of the screw coupling before starting, the fourth generation electric wrench can automatically realize the required tightening force (current error is 5%) after running. This electric wrench is temporarily called an electric wrench with controllable preload.

　　第四代電動扳手不僅能控制螺桿接頭副達到要求的擰緊軸向力，而且能滿足高強度螺栓接頭副擰入機體的要求，這在過去是很難做到的。此外，配合第四代電動扳手的螺紋連接副也可重復使用。

　　The fourth generation electric wrench can not only control the screw joint pair to achieve the required tightening axial force, but also meet the requirements of high strength bolt joint pair to screw into the body, which was difficult to achieve in the past. In addition, the threaded connection pair with the fourth generation electric wrench can also be reused.

　　4結論

　　4 Conclusion

　　電動扳手的第四代是目前世界上比較的電動扳手,用于螺桿高強度螺栓連接副,這將使關節(jié)的收緊軸向力對更準確,施工更方便,這將徹底改變電動扳手和加捻技術。將這項技術推廣到其他行業(yè)(比如空客380，它要求嚴格控制機翼和機身之間每一對連接的軸向力)也將提高螺栓連接的質量。

　　The fourth generation of electric wrench is the most advanced electric wrench in the world. It is used in high strength bolt connection pair of screw. This will make the joint tightening axial force more accurate and construction more convenient, which will completely change the electric wrench and twisting technology. Extending this technology to other industries (such as Airbus 380, which requires strict control of the axial force of each pair of connections between the wing and fuselage) will also improve the quality of bolted connections.