Electric wrench is an electric tool for tightening and loosening bolts and nuts. It is a tool for tightening high strength bolts. It is used for the initial tightening and final tightening of large hexagon head high strength bolts in the installation of steel structure bridges, factory buildings, chemical industry and power generation equipment, as well as the initial tightening of torsional shear type high strength bolts, and the occasions where there are strict requirements on the torque or axial force of bolt fasteners.

电动扳手的产品名称型号不同，用途使用范围也不同。这里介绍定转矩电动扳手，供使用参考。

The product name and model of electric wrench are different, and the application range is also different. This paper introduces the constant torque electric wrench for reference.

电动扳手简述

Brief introduction of electric wrench

定转矩电动扳手是一种能自动控制转矩的电动扳手。它适用于需要用高强度螺栓连接的桥梁结构、大型钢塔、钢结构厂房、冶金设备的构架、大型起重机架、矿井钢架等工程中及大型柴油机、发电设备、化工设备中，要求恒定的夹紧力连接的螺栓也可用定转矩扳手来紧固。

Constant torque electric wrench is a kind of electric wrench which can control the torque automatically. It is suitable for the bridge structure, large steel tower, steel structure workshop, metallurgical equipment frame, large crane frame, mine steel frame and other projects that need to be connected with high-strength bolts, as well as large diesel engine, power generation equipment and chemical equipment. The bolts that require constant clamping force can also be fastened with constant torque wrench.

特别在现代桥梁建设中，定转矩电动扳手是实现以“栓焊梁”代替“铆焊梁”的有效工具。这对简化工地安装工序、降低建桥成本、减轻劳动强度，从而加速桥梁建设具有较大的意义。

Especially in modern bridge construction, constant torque electric wrench is an effective tool to replace riveted beam with "bolted beam". It is of great significance to simplify the site installation process, reduce the cost of bridge construction, reduce the labor intensity and accelerate the bridge construction.

定转矩电动扳手的转矩以电气装置来进行控制。这种电动扳手具有耗电量少、噪声小、调节灵活、能自动停机、转矩稳定等优点。

The torque of constant torque electric wrench is controlled by electric device. The electric wrench has the advantages of low power consumption, low noise, flexible adjustment, automatic shutdown and stable torque.

我国自行设计、制造的120kgf·m定转矩电动扳手是一种静转矩结构的扳手。它可作为高强度螺栓的终拧工具，即把初拧过的螺栓再拧到规定的力矩。

The 120kgf · m constant torque electric wrench designed and manufactured by our country is a kind of wrench with static torque structure. It can be used as the final tightening tool for high strength bolts, that is, to screw the initially tightened bolts to the specified torque.

电动扳手是装卸螺纹联接件的手持式电动工具，广泛应用于汽车、拖拉机、电机电器、动力机械、阀门、水泵、纺织机械等制造业的装配工作中，在化工、水泥预制件、塑料成型等作业中则用于生产流程中装拆真空罐、反应釜和水泥模板、带螺纹塑料件的脱模工作；也可用在铁道、桥梁、建筑等工程中作水泥轨枕、桁架节点、角钢脚手架等结构的安装、检修和拆换工作。

Electric wrench is a hand-held electric tool for loading and unloading threaded connectors. It is widely used in the assembly work of automobile, tractor, motor and electrical appliances, power machinery, valve, water pump, textile machinery and other manufacturing industries. In the chemical industry, cement prefabrication, plastic molding and other operations, it is used to assemble and disassemble vacuum tanks, reactors and cement templates in the production process Demoulding of threaded plastic parts; It can also be used for the installation, maintenance and replacement of cement sleepers, truss joints, angle steel scaffolds and other structures in railway, bridge, construction and other projects.

电动扳手原理

Principle of electric wrench

当螺母的端面与工件端面接触后，阻力矩急剧上升，转动的螺旋槽使滚珠带着主动冲击块克服摩擦力和工作弹簧的压力向后移动，使主动冲击块与从动冲击块互相啮合的牙脱离啮合。此时，从动冲击块不移动，而主动冲击块继续向后移动。在转过从动冲击块的牙后，由于工作弹簧的作用使主动冲击块瞬时前移，并沿螺旋槽产生一个角加速度，主动冲击块撞击从动冲击块，两牙产生碰撞。然后螺旋槽又使滚珠和主动冲击块后移，脱离啮合。这样周而复始产生一次又一次的碰撞，获得所需的冲击力矩，使螺母紧固。

When the end face of the nut contacts with the end face of the workpiece, the resistance moment rises sharply, and the rotating spiral groove makes the ball with the active impact block move backward to overcome the friction and the pressure of the working spring, so that the teeth of the active impact block and the driven impact block are out of mesh. At this time, the driven impactor does not move, while the active impactor continues to move backward. After turning the teeth of the driven impactor, due to the action of the working spring, the active impactor moves forward instantaneously and generates an angular acceleration along the spiral groove. The active impactor impacts the driven impactor and the two teeth collide. Then the spiral groove makes the ball and the active impact block move back and out of mesh. In this way, repeated collisions are produced, and the required impact torque is obtained to tighten the nut.

如将电源开关接到反转位置即可拧出螺母。双重绝缘单相串励电动扳手在操作手柄上装有两只开关。一只为工作开关，是操纵起动和停止的；另一只是专门为改变电枢正反转而设置的，两只开关不可接反。

If the power switch is connected to the reverse position, the nut can be screwed out. The double insulation single-phase series excitation electric wrench is equipped with two switches on the operating handle. One is the working switch, which controls the start and stop; The other is specially designed to change the armature forward and reverse, and the two switches can not be connected reversely.