Sheet Metal Air Bending for Pressbrakes

Sheet Metal Air Bending for Pressbrakes

For sheet metal  press brake bending&forming, a work piece is positioned over the die block and the die block presses the sheet to form a shape. Usually sheet  bending has to overcome both tensile stresses and compressive stresses. When metal bending is done, the residual stresses cause the material to spring back towards its original position, so the sheet must be over-bent to achieve the proper bend angle. The amount of spring back is dependent on the material, and the type of forming. 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 edges of the bend. The bend radius refers to the inside radius. The formed bend radius is dependent upon the dies used, the material properties, and the material thickness.

Air bending is one common and very important for sheet metal bending which used in Hydraulic pressbrake, NC&CNC brake press,

This metal bending method forms material by pressing a punch (also called the upper or top die) into the material, forcing it into a bottom V-die, which is mounted on the pressbrakes. 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 (T).

Either a V-shaped or square opening may be used in the bottom die (dies are frequently referred to as tools or tooling). Because it requires less bend force, air bending tends to use smaller tools than other methods.

Some of the newer bottom tools are adjustable, so, by using a single set of top and bottom bending tools and varying press-stroke depth, different profiles and products can be produced. Different materials and thicknesses can be bent in varying bend angles, adding the advantage of flexibility to air bending. There are also fewer tool changes, thus, higher productivity.

A disadvantage of air bending is that, because the sheet does not stay in full contact with the dies, it is not as precise as some other methods, and stroke depth must be kept very accurate. Variations in the thickness of the material and wear on the tools can result in defects in parts produced.

Air bending's angle accuracy is approximately ±0.5 deg. Angle accuracy is ensured by applying a value to the width of the V opening, ranging from 6 T (six times material thickness) for sheets to 3 mm thick to 12 T for sheets more than 10 mm thick. Springback depends on material properties, influencing the resulting bend angle.

Depending on material properties, the sheet may be overbent to compensate for springback.

Air bending does not require the bottom tool to have the same radius as the punch. Bend radius is determined by material elasticity rather than tool shape.

The flexibility and relatively low tonnage required by air bending are helping to make it a popular choice. Quality problems associated with this method are countered by angle-measuring systems, clamps and crowning systems adjustable along the x and y axes, and wear-resistant tools.

The K-factor approximations given below are more likely to be accurate for air bending than the other types of bending due to the lower forces involved in the forming process.

AHYW Covered the following different type sheet metal pressbrakes for your bending

AHYW NC Pressbrakes

AHYW Synchro CNC Presssbrakes, 4 axis, 6 axis&8 axis cnc brake press machine Yawei made in China

AHYW Hybrid Pressbrakes