BeckwoodBending (metalworking) is aSheet Metal Hand Panel Flanger Joggle Pliers going out for aJoggle
A V-shape, U-shaped, or channel shape along a straight axis in sheet metal is a result of bending.Box and pan brakes, brake presses, and other specialized machine presses are commonly used.boxes such as electrical enclosures and rectangular ductwork are typical products made like this.
The die block presses the sheet to form a shape when a work piece is positioned over it.bending has to overcome both stresses.When bending, the residual stresses cause the material to fall back towards its original position.The amount of spring back depends on the type of forming and material.It stretches when sheet metal is bent.The amount of sheet metal that will stretch when bent is called the bend deduction.The inside radius is referred to as the bend radius.The bend radius is dependent on dies used, material properties, and thickness.
Three basic types of bending on a press brake are defined by the relationship between the end position tool and the thickness of the material.The three are called air bending, bottoming and coining.The three types of bending have the same configuration of tools.A punch is a die with a long rail form tool that locates the inside profile of the bend.The bending force is produced by attaching punches to the ram of the machine.A die with a long rail form tool that is V shaped is called a die.The dies are located under the bed of the machine.Some locations do not differentiate between punches and dies.Other types of bending use specially designed tools or machines.
The bending method involves pressing a punch into the material, forcing it into a bottom V-die, which is mounted on the press.The punch forms the bend so that the distance between the punch and the side wall of the V is greater than the material thickness.
The bottom die may have either a V-shaped or square opening.Air bending uses smaller tools than other methods because it requires less bend force.
By using a single set of top and bottom tools and varying press-stroke depth, different profiles and products can be produced.The advantage of air bending is that different materials and thicknesses can be bent in different angles.Higher productivity can be achieved by fewer tool changes.[3]
Air bending is not as precise as other methods due to the fact that the sheet does not stay in full contact with the dies.Defects in parts can be caused by variations in the thickness of the material and wear on the tools.The use of adequate process models is important.[4]
Air bending's angle accuracy is very low.Applying a value to the width of the V opening is how angle accuracy is ensured.The bend angle is influenced by material properties.[3]
The punch has the same radius as the bottom tool.The bend radius is determined by material elasticity.[3]
It is a popular choice due to the flexibility and low amount of tonnage required by air bending.Quality problems associated with this method are countered by angle-measuring systems, clamps and crowning systems that are adjusted along the x and y axes, and wear-resistant tools.[3]
The lower forces involved in the forming process make the K-factor approximations more accurate for air bending.
The sheet is forced against the V opening in the bottom tool.U-shaped openings can't be used.There is space between the sheet and the V opening.Up to 12 T is the optimum width of the V opening for sheets up to 3mm thick.For sheet steel, the bending radius must be at least 0.8 T.The force required for bottoming is the same as for air bending, but smaller bend radii require more force.The advantages of bottoming are greater accuracy and less springback.Different tool sets are needed for each bend angle, sheet thickness, and material.The preferred technique is air bending.[3]
In coining, the top tool forces the material into the bottom die with a force greater than the force of air bending.There isn't much to spring back.With a 5 T width of the V opening, coining can produce an inside radius of as low as 0.4 T.Higher costs mean that coining is not often used.
Three-point bending uses a die with a bottom tool that is moved by a motor.The height can be set.The ram and upper tool are adjusted using a cushion that accommodates deviations in sheet thickness.bend angles can be achieved with three-point bending.It was precision.Three-point bending permits high flexibility and precision, but it also entails high costs and there are fewer tools available.It is being used in niche markets.[3]
The longer side of the sheet can be folded.The sheet is folded around the bend profile.The bend beam allows the fabrication of parts with positive and negative bend angles.The folding angle of the beam, tool geometry, and material properties affect the resulting bend angle.Large sheets can be handled in this process.There is no risk of damage to the sheet.[3]
The tool moves up and down as it bends the sheet around the bend profile.Because the tool is moving over the sheet surface, wiping has a higher risk of damaging it.If angles are being produced, the risk increases.[3]
The method of coining or bottoming the material will help overcome springback.The final bending radius is determined by the bottom die's radius.
The top die is made of a freely rotating cylinder with the shape cut into it and a matching bottom die.As the forming process bends the sheet, the roll contacts on two points and rotates.This bending method can be used for pre-painted or easily marred surfaces.The bending process can produce angles greater than 90 in a single hit.
The curve is created by the roll bending process.There needs to be an allowance for pre-punching.
The bottom V-die is replaced with a flat pad of rubber.The material forms around the punch as it forms the part.There are a number of advantages to this method.The end bend radius will be very close to the punch and the material will wrap around it.It is suitable for pre-painted or sensitive materials.Using a special punch called a radius ruler with relieved areas on the U-bends greater than 180 can be achieved in one hit, something that is not possible with conventional press tooling.While they are not cheap, methane tooling is a fraction of the cost of dedicated steel.This method requires a lot of tonnage similar to bottoming and coining, and does not do well on flanges that are irregular in shape, that is where the edge of the bent flanges is not parallel to the bend and is short enough to engage the urethane pad.
Joggling, also known as joggle bending, is an offset bending process in which two opposite bends with equal angles are formed in a single action creating a small s-shape bend profile.In order to allow a lap joint where the edge of one sheet of material is laid on top of the other, the offset will often be one material thickness.
There are many variations of these formulas online.The variations seem to be at odds with one another, but they are the same formulas simplified or combined.The unsimplified formulas are presented here.The following keys are used in all formulas.
The neutral line is an imaginary profile that can be drawn through a cross-section of the workpiece that represents the location where shear stresses are at their maximum.In the bend region, the material between the neutral line and the inside radius will be under compression while the outside radius is under tension.The location of the part in the material is dependent on the forces used to form it.The geometric definition of the plane represents the unbent flat pattern shape within the cross-section of a bent part.The opening of the bottom die affects the bend allowance in air bending.The bending process is more complicated than it appears.
The neutral line or unbent flat pattern and the formed bend are represented by the bend deduction and bend allowance.The flat pattern length is given by subtracting them from the combined length of the two flanges.The question of which to use is determined by the method used to define the flanges shown in the two diagrams below.Due to the geometric transformation, the length of the flat pattern is always shorter than the total length.The bend deduction and bend allowance are related to the distance that each bend stretches.A careful examination of the formulas and stresses involved show that this is not true.
Sheet metal functions or add-ons are included in most 3D Solid Modeling CAD software.[9]
The bend allowance is the length of the neutral line between the points of a bend.The Flat Pattern length is given by adding the length of each flange as shown in the diagram to the BA.The bend allowance formula can be used to determine the length of the pattern when the bend is from one side to the other.Before adding in the bend allowance, the material thickness and bend radius have to be subtracted from each other.
The initial flat length is defined as the difference between the sum of the flange lengths from the edge to the apex.
The outside set back is the length from the top of the bend to the bottom.The bend allowance is less than the outside setbacks.The angle in radians is calculated using the formula.
K-factor is a ratio of the neutral line's location to the material thickness as defined by t/T.The K-factor formula does not take the forming stresses into account but is simply a geometric calculation of the neutral line location after the forces are applied and is thus the roll-up of all the unknown (error) factors for a given setup.The K-factor is dependent on many variables including the material and the type of bending operation.The tools.It can be between 0.2 and 0.5.