Sheet Bending Process and Machines
Sheet bending is a process of metal forming through which metals are bent into desired forms. In a sheet bending process the metals are casted into the required form by exerting a strong force on them. The force applied on the metal actually causes it to deform along one axis only but by applying the force repeatedly with a sequence of different operations the metals can be deformed along multiple axes thus forming the shape desired out of the metal piece.
In the process, the metal experiences both tension as well as compression. The tension will cause the outer part of the work piece to stretch further in the length where as the inside portion will experience the compression and will be shortened due to the force exerted. Apart from these two factors, the metal will also be subjected to residual stresses after the bending and these forces will try to slightly get back the metal to its original shape. For this reason the metal is often subjected to a little much bending than required so that the accurate sheet bending can be acquired in spite of the residual stresses acting on it.
To achieve bending, the metals need to be stressed beyond their yield strength and below the tensile strength and this is not at all an easy task as metals are very hard substances. Therefore to achieve sheet bending, most often the tools like press brakes, shearing, power press and bending roller are used especially for the industrial applications where the quantity requirement is large.
Press brake is one of the basic and popular forms of sheet bending machinery. Available in manual and automated versions, this machine is used to bend metals of different kinds in wide variety of industrial applications. In press brake the metal deformation is achieved by placing it between tools called punch and dies. Punch is the upper tool that exerts force on the metal piece where as the die is the bottom tool casted in a specific shape into which the metal will be casted when force is exerted on it. While metal is subjected to force of the punch, it is held back in position with a back gauge so that accurate bending with accurate angles can be achieved without any disturbance in positioning of the work piece. With various techniques and types of punch and die tooling, the customized bending can be achieved. For severe, faster or bulk tasks, when required to be performed on the harder metals, use of stronger tooling will efficiently serve the purpose.
It is one of the most important variants of sheet bending. It is usually available in two types of constructions – C type frame and pillar type frame. In c type the built frame of the machine is similar to that of alphabetical ‘C’ shape and therefore it is called as C type power press where as in pillar type the frame of the machine is pillar type. Both the types give an efficient performance in cutting, pressing, bending and forming the sheet metals into different shapes and sizes.
Apart from these, there are even the shearing machines which can be employed for cutting large sheets, bars and plates of metallic and non-metallic materials into different shapes and therefore are utilized in industries like automobile, printing, food processing, engineering, electronic, plastic, wood working, electrical, construction for various metal shearing tasks.