Power Tool: Impact Wrench
Posted on: July 25, 2016
Most popularly referred to as an impact gun or an air gun or simply just as an air wrench, the impact wrench is a construction tool that is designed to minimize the input effort of the user while simultaneously delivering high power output. This is achieved by storing the high torque energy in a temporary power source. This power source can store energy in the form of compressed air, hydraulic power or the most popular, electromagnetic torque energy.
This stored energy is conserved in the power source for the period of inactivity of the wrench. When the wrench is put into use, the stored energy is released suddenly and delivered to the output shaft. This makes the shaft rotate at very high speed and generating very high torque. The impact wrench is thus, able to move rotate high inertia loads at high speeds. The output energy is obtained in the form of rotational energy, that is generally utilized for tightening, rotating or fixing applications. The are many types of impact wrenches like pneumatic impact wrenches and air impact wrenches. These wrenches find application in various industries like construction industry, power industry, mechanical industry and electrical instrumentation industry.
Principle of working an operation:
The most common type of impact wrenches used are air impact wrenches, and they work on the hammer and anvil principle. In this technique, an object of high mass is rotated and accelerated with the help of the power source. This mass is called the hammer and it stores the energy. When sufficient acceleration is obtained, the hammer is connected to the anvil. This creates a very high torque impact on the output terminal. Immediately after the high torque output impact, the hammer is isolated from the anvil and is allowed to rotate freely on no load.
The main advantage of this approach is that, the reactive force received on the body of the wrench is minimized. This means that the jerk felt by the person holding the wrench is very less. The only reactive force felt by the user is when the motor rotates the hammer to very high speeds. This is analogous with the working of the real hammer and anvil mechanism, in which the user implies minimum force on the hammer to swing it, but delivers very high impulse at the receiving end of the anvil.
Extensions for the impact wrench
The aim of any extension and accessory attached to the impact wrench is to maximize the output torque at the socket while minimizing the reactive force. This cannot be achieved if the material used for hammer extension contains spring properties. Thus, materials with high tensile strength are used for production of hammer extensions.
Nevertheless, we must keep in mind that, with the increase in the length of the extension and the number of universal joints in the hammer, the overall mechanical strength of the wrench and the net output torque impact is reduced.
The impact wrench plays a very crucial role in power industries that require high power applications complemented with human skill. The impact wrenches allow the worker to deliver high torque impact at the precise location and time.
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