Bending is a common
metalworkingMetalworking is the process of working with metals to create individual parts, assemblies, or large scale structures. The term covers a wide range of work from large ships and bridges to precise engine parts and delicate jewellery. It therefore includes a correspondingly wide range of skills,...
technique to process
sheet metalSheet metal is simply metal formed into thin and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material...
. It is usually done by hand on a
box and pan brakeA brake is a metalworking machine that allows the bending of sheet metal. A cornice brake only allows for simple bends and creases, while a box-and-pan brake also allows one to form box and pan shapes...
, or industrially on a
brake pressA press brake, also known as a brake press or just brake, is a machine tool mainly for the bending sheet metal.-Types:A brake can be described by basic parameters, such as the force or tonnage and the working length...
or
machine brakeA press, or a machine press is a tool used to work metal by changing its shape and internal structure.A forge press reforms the work piece into a three dimensional object—not only changing its visible shape but also the internal structure of the material...
. Typical products that are made like this are boxes such as electrical enclosures, rectangular
ductworkDucts are used in heating, ventilation, and air conditioning to deliver and remove air. These needed airflows include, for example, supply air, return air, and exhaust air. Ducts also deliver, most commonly as part of the supply air, ventilation air...
, and some firearm parts such as the receiver of the
AKMThe AKM is a 7.62mm assault rifle designed by Mikhail Kalashnikov. It is an upgraded version of the AK-47 rifle and was developed in the 1950s...
AK-47The AK-47 is a selective fire, gas operated 7.62mm assault rifle developed in the Soviet Union by Mikhail Kalashnikov in the 1940s. Six decades later, the AK-47 and its variants and derivatives remain in service throughout the world...
variant.
Usually bending has to overcome both tensile stresses as well as compressive stresses.
Bending is a common
metalworkingMetalworking is the process of working with metals to create individual parts, assemblies, or large scale structures. The term covers a wide range of work from large ships and bridges to precise engine parts and delicate jewellery. It therefore includes a correspondingly wide range of skills,...
technique to process
sheet metalSheet metal is simply metal formed into thin and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material...
. It is usually done by hand on a
box and pan brakeA brake is a metalworking machine that allows the bending of sheet metal. A cornice brake only allows for simple bends and creases, while a box-and-pan brake also allows one to form box and pan shapes...
, or industrially on a
brake pressA press brake, also known as a brake press or just brake, is a machine tool mainly for the bending sheet metal.-Types:A brake can be described by basic parameters, such as the force or tonnage and the working length...
or
machine brakeA press, or a machine press is a tool used to work metal by changing its shape and internal structure.A forge press reforms the work piece into a three dimensional object—not only changing its visible shape but also the internal structure of the material...
. Typical products that are made like this are boxes such as electrical enclosures, rectangular
ductworkDucts are used in heating, ventilation, and air conditioning to deliver and remove air. These needed airflows include, for example, supply air, return air, and exhaust air. Ducts also deliver, most commonly as part of the supply air, ventilation air...
, and some firearm parts such as the receiver of the
AKMThe AKM is a 7.62mm assault rifle designed by Mikhail Kalashnikov. It is an upgraded version of the AK-47 rifle and was developed in the 1950s...
AK-47The AK-47 is a selective fire, gas operated 7.62mm assault rifle developed in the Soviet Union by Mikhail Kalashnikov in the 1940s. Six decades later, the AK-47 and its variants and derivatives remain in service throughout the world...
variant.
Usually bending has to overcome both tensile stresses as well as compressive stresses. When bending is done, the residual stresses make it spring back towards its original position, so we have to overbend the sheet metal keeping in mind the residual stresses.
When sheet metal is bent, it stretches in length. The bend deduction is the amount the sheet metal will stretch when bent as measured from the outside. A bend has a radius. The term bend radius refers to the inside radius. The bend radius depends upon the dies used, the metal properties, and the metal thickness.
Many software packages refer to the K-factor for bending sheet metal. K-factor is a ratio that represents the location of the neutral sheet with respect to the inside thickness of the sheet metal part. The bend allowance is the length of the arc of the neutral axis between the tangent points of a bend in any material.
- BD = 2*(R + T) - BA
- BA = π*(R + K*T)*A/180
- K = (180 * BA)/(π*A*T) - R/T
where:
- BA = bend allowance
- R = inside bend radius
- K = K-Factor, which is t / T
- T = material thickness
- t = distance from inside face to neutral sheet
- A = bend angle in degrees (the angle through which the material is bent)