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Project Quick details
Material:Sheet metal, SPCC, aluminium board
Manufacturing Process:CNC bending
Finish Treatmentolishing, baking paint, powder coating, Electroplating, passivation
Difficulties & Highlights:Big size, should control the deformation to assure the assembly.
SizeCustomer's 3D/2D drawing
Brand nameNoble
Palace of originShenzhen, China (mainland)
What can we do?
Bending of sheet metal is a common and vital process in manufacturing industry. Sheet metal bending is the plastic deformation of the work over an axis, creating a change in the part's geometry. Similar to other metal forming processes, bending changes the shape of the work piece, while the volume of material will remain the same. In some cases bending may produce a small change in sheet thickness. For most operations, however, bending will produce essentially no change in the thickness of the sheet metal. In addition to creating a desired geometric form, bending is also used to impart strength and stiffness to sheet metal, to change a part's moment of inertia, for cosmetic appearance and to eliminate sharp edges.
Figure:264  
Metal bending enacts both tension and compression within the material. Mechanical principles of metals, particularly with regard to elastic and plastic deformation, are important to understanding sheet metal bending and are discussed in the fundamentals of metal forming section. The effect that material properties will have in response to the conditions of manufacture will be a factor in sheet metal process design. Usually sheet metal bending is performed cold but sometimes the work may be heated, to either warm or hot working temperature.
Most sheet metal bending operations involve a punch die type setup, although not always. There are many different punch die geometries, setups and fixtures. Tooling can be specific to a bending process and a desired angle of bend. Bending die materials are typically gray iron, or carbon steel, but depending on the work piece, the range of punch-die materials varies from hardwood to carbides. Force for the punch and die action will usually be provided by a press. A work piece may undergo several metal bending processes. Sometimes it will take a series of different punch and die operations to create a single bend. Or many progressive bending operations to form a certain geometry.
Sheet metal is referenced with regard to the work piece when bending processes are discussed in this section. However, many of the processes covered can also be applied to plate metal as well. References to sheet metal work pieces may often include plate. Some bending operations are specifically designed for the bending of differently shaped metal pieces, such as for cabinet handles. Tube and rod bending is also widely performed in modern manufacturing.
Bending Processes
Bending processes differ in the methods they use to plastically deform the sheet or plate. Work piece material, size and thickness are important factors when deciding on a type of metal bending process. Also important is the size of the bend, bend radius, angle of bend, curvature of bend and location of bend in the work piece. Sheet metal process design should select the most effective type of bending process based on the nature of the desired bend and the work material. Many bends can be effectively formed by a variety of different processes and available machinery will often determine the bending method.
One of the most common types of sheet metal manufacturing processes is V bending. The V shaped punch forces the work into the V shaped die and hence bends it. This type of process can bend both very acute and very obtuse angles, also anything in between, including 90 degrees.
Figure:265
Edge bending is another very common sheet metal process and is performed with a wiping die. Edge bending gives a good mechanical advantage when forming a bend. However, angles greater than 90 degrees will require more complex equipment, capable of some horizontal force delivery. Also, wiping die employed in edge bending must have a pressure pad. The action of the pressure pad may be controlled separately than that of the punch. Basically the pressure pad holds a section of the work in place on the die, the area for the bend is located on the edge of the die and the rest of the work is held over space like a cantilever beam. The punch then applies force to the cantilever beam section, causing the work to bend over the edge of the die.
Figure:266
Rotary bending forms the work by a similar mechanism as edge bending. However, rotary bending uses a different design than the wiping die. A cylinder, with the desired angle cut out, serves as the punch. The cylinder can rotate about one axis and is securely constrained in all other degrees of motion by its attachment to the saddle. The sheet metal is placed cantilevered over the edge of the lower die, similar to the setup in edge bending. Unlike in edge bending, with rotary bending, there is no pressure pad. Force is transmitted to the punch causing it to close with the work. The groove on the cylinder is dimensioned to create the correctly angled bend. The groove can be less than or greater than 90 degrees allowing for a range of acute and obtuse bends. The cylinders V groove has two surfaces. One surface contacts the work transmitting pressure and holding the sheet metal in place on the lower die. As force is transmitted through the cylinder it rotates, causing the other surface to bend the work over the edge of the die, while the first surface continues to hold the work in place. Rotary bending provides a good mechanical advantage.
This process provides benefits over a standard edge bending operation, in that it eliminates the need for a pressure pad and it is capable of bending over 90 degrees without any horizontally acting equipment. Rotary bending is relatively new and is gaining popularity in manufacturing industry.
Figure:267
Air bending is a simple method of creating a bend without the need for lower die geometry. The sheet metal is supported by two surfaces a certain distance apart. A punch exerts force at the correct spot, bending the sheet metal between the two surfaces.
Figure:268

Punch and die are manufactured with certain geometries, in order to perform specific bends. Channel bending uses a shaped punch and die to form a sheet metal channel. A U bend is made with a U shaped punch of the correct curvature.
Figure:269
Many bending operations have been developed to produce offsets and form the sheet metal for a variety of different functions.
Figure:270
Some sheet metal bending operations involve the use of more than 2 die. Round tubes, for example, can be bent from sheet metal using a multiple action machine. The hollow tube can be seamed or welded for joining.
Figure:271
Corrugating is a type of bending process in which a symmetrical bend is produced across the width of sheet metal and at a regular interval along its entire length. A variety of shapes are used for corrugating, but they all have the same purpose, to increase the rigidity of the sheet metal and increase its resistance to bending moments. This is accomplished by a work hardening of the metal and a change in the sheet's moment of inertia, caused by the bend's geometry. Corrugated sheet metal is very useful in structural applications and is widely used in the construction industry.
Figure:272

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