Sheet Metal Bending Machine and Bending Die FAQ
Anyone familiar with sheet metal processing engineering knows that bending is one of the more challenging and technically demanding processes in sheet metal fabrication.
(1) What is sheet metal bending?
Sheet metal bending is the process of transforming flat sheet metal into a three-dimensional shape through the use of pressure equipment and specially designed dies.
Due to the varying materials, thicknesses, lengths, widths of the sheet metal, and the different shapes and angles required for forming, there are bending machines with different tonnages and sizes equipped with upper and lower dies of different heights, shapes, and V-widths along with special dies for special shapes.
(2) What are the types of bending processes?
There are three types of bending processes: air bending, bottoming, and coining.
① Air bending is done using an upper die of less than 88° and a lower die with a V=12t (where V is the die opening, and t is the material thickness) for right-angle and obtuse angle bends.
② Bottoming is done using a 90° upper die for right-angle and obtuse angle bends. The bottoming lower die uses a V=6~12t.
③ Coining is done using a 90° upper die for a standard right-angle bend. The coining lower die uses a V=5~6t.
(3) How to use a bending machine?
Currently, there are many types of bending machines for sheet metal processing, which can be categorized by their driving mechanism into mechanical (servo motor) and hydraulic types, by their control system into simple manual bending machines, ordinary domestic digital position bending machines, and process control digital full-function bending machines, and by their operational parts into 4-axis, 8-axis, 12-axis, etc., bending machines. ① Before using a bending machine, check if the power supply is connected, if the air pressure is sufficient, if the hydraulic fluid is full, if the machine is clean, and if there are any obstacles on the slide way. Proceed with subsequent steps only after confirmation.
② Turn on the machine power switch, start the oil pump, align the L axis, D axis, CC axis, Z axis to their origin points, and complete the start-up process.
③ For die setup, after selecting the appropriate dies, set the machine's gear switch to the "cut" position, install the base and the lower and upper dies, then set the machine's switch to the inching or single action position. Use the foot pedal to raise the switch, shake the handle or knob to raise, combine the upper and lower dies under pressure, align the D axis to zero point, and lock the lower die to complete the die setup process.
(4) How to use bending dies?
Bending dies come in several types, such as L-type, R-type, U-type, Z-type, etc. The upper dies are available in different angles, including 90°, 88°, 45°, 30°, 20°, 15°, etc. The lower dies consist of double-slot and single-slot dies with different V-widths ranging from 4 to 18V. There are also R-type lower dies, acute angle lower dies, flattening dies, etc. The upper and lower dies can be segmented or solid: segmented upper dies are typically 300mm, 200mm, 100mm, 50mm, 40mm, 20mm, 15mm, and 10mm, while the solid upper die length is 835mm. The lower dies are usually segmented into 400mm, 200mm, 100mm, 50mm, 40mm, 20mm, 15mm, and 10mm, with a solid length of 835mm.
① Bending dies are made of high-quality steel and undergo special heat treatment, resulting in high hardness, resistance to wear, and the ability to withstand high pressure. However, each set of dies has a maximum pressure it can handle, expressed as tons per meter. Therefore, when using the dies, it is essential to select the appropriate die length based on the required pressure per meter, ensuring it does not exceed the specified pressure limit of the die.
② To avoid damaging the dies, it is mandated that when setting the origin point, upper and lower dies with a length of at least 300mm must be used. Only after setting the origin point correctly can the same height upper and lower dies be used. It is strictly prohibited to use segmented small dies for setting the origin point, and the origin point must be set according to the standard origin pressure within the AMADA machine.
③ Due to the varying heights of different dies, when selecting dies on a machine, only dies with the same height can be used. Different height dies should not be mixed.
④ When using the dies, it is necessary to select the appropriate upper and lower dies based on the material hardness, thickness, and length of the metal sheet. Generally, the lower die is used according to the standard of 5~6T, with a length slightly longer than the sheet. For harder materials and thicker sheets, a wider V-width lower die should be used.
⑤ When bending sharp angles or hemming edges, a 30-degree upper die should be used, with the sharp angle bent first and the edge hemmed afterward. For bending R-angles, R-type upper and lower dies should be used.
⑥ For longer workpieces, it is advisable to avoid using segmented dies to reduce the marking caused by the joint. It is also preferable to use single-slot dies since they have a larger outer corner radius in the V-groove, reducing the risk of bending marks.
⑦ When selecting the upper die, the specific type of upper die to be used should be determined based on the parameters of all the dies and the desired shape of the product to be formed.
⑧ It is not allowed to use dies to bend steel bars or other cylindrical products when they have an extremely high hardness or when the sheet is too thick.
⑨ When using the dies, it is important to stay focused. After the machine has set the origin point, the upper and lower dies should be locked to prevent them from falling and causing injury or damage to the dies. During the operation, attention should be paid to the pressure applied, avoiding sudden excessive force, and monitoring the data displayed on the screen.
⑩ After using the dies, they should be promptly returned to the die rack and placed according to their identification marks. Regularly clean the dust from the dies and apply rust preventive oil to prevent rusting and maintain die precision.
