Sheet Metal Forming
Forming processes are capable of bending and stretching sheet material into the desired shape without causing the material to fail. Entailing the application force that causes the material to plastically deform, forming processes include:
Here, a force is applied to a piece of stock (sheet metal) causing it bend at an angle, effectively achieving the desired shape. Bending processes result in deformation along one axis, but with a sequence of processes, more complex parts can be formed.
Note that bending operations do result in compression and tension. The outside of the sheet metal being bent will undergo tension as it stretches to a greater length. The inside section of the portion that experiences the stretch, will now experience compression.
Another important factor to consider regarding bending is springback. Due to elastic recovery, sheet material needs to be over-bend to an exact measurements in order to achieve the exact bend angle and bend radius required.
Typical machines used for bending processes include press brakes, but custom tooling can also be used to create specialized bending processes. Other processes used for bending also includes V-Bending and Wipe Bending.
This sheet metal fabrication process entails the sheet metal to be stretched into a desired shape by using a tool, pushing downwards, to push the sheet material into a die cavity (which is in the shape of the required part).
An effective process for ductile metals such as mild steel and aluminum, deep drawing creates a number of everyday products ranging from pots and pans, to fuel tanks and automotive bodies.
Entailing sheet metal to be progressively shaped through a series of bending operations, the roll forming process involves a roll forming line in which sheet stock is fed through a series of roll stations, each station featuring a roller die, positioned on both sides of the sheet being formed.
Note that these roller dies, lubricated in order to reduce the friction created between the sheet metal and the die, can be positioned below, above, at an angle or along the sides of the sheet metal being formed.
The roller dies used can be unique to every station, or identical roller dies can be used in different positions.
Used to form cylindrical parts, spinning entails the rotation of sheet metal stock while a force is applied to this stock at one side. Typically performed on a CNC or manual lathe, spinning requires a roller tool, blank and mandrel.
The blank is the disc-shape sheet metal (pre-cut) with the mandrel being the solid form of the internal shape to be formed. The blank is pressed against the mandrel and, for more complex parts, multi-piece mandrels can be used.
The roller wheel is responsible for applying force as the blank and mandrel rotate, resulting in the sheet being bent around the mandrel.
Two spinning methods are used, which includes:
- Here, the roller tool is pressed against the blank until it conforms to the shape of the mandrel. The now spun part will have a smaller diameter than the blank and have a constant thickness.
- In shear spinning, the roller tool is not only responsible for bending the blank against the mandrel, but is also applies a downward force as it moves. This causes the sheet metal to stretch over the mandrel. With this spinning process, spun parts will remain equal to the original blank diameters with the wall thicknesses of the parts being thinner.
This forming process entails a piece of stock (sheet metal) being bent and stretched over a form die, resulting in the formation of large, contoured parts. Bending and stretching occurs simultaneously and this process is commonly used to form large radius bends.
Stretch forming is capable of producing simple curved surfaces as well as complex, non-uniform cross sections, with the most common materials shaped including steel, aluminum and titanium.
Parts formed using this process range from wing panels on airplanes and door panels on cars, to enclosures and window frames.