(1) What is sheet metal bending?
Sheet metal bending is the process of using pressure equipment and specialized molds to transform flat metal sheets into three-dimensional shapes, known as bending.
Due to different materials, thicknesses, lengths, widths of sheets, and the required shapes and angles, there are bending machines with different tonnage and pressure capacities. They are equipped with special molds of different heights, shapes, and V-widths.
(2) What are the types of bending processes?
Bending processes can be divided into three categories: partial bending, close bending, and stamping bending.
① Partial bending involves using upper dies below 88° and lower dies with V=12t (V represents the slot width, and t represents the material thickness) for right-angle and obtuse-angle bending.
② Close bending involves using upper dies at 90° for right-angle and obtuse-angle bending. The lower dies for close bending have V=6~12t.
③ Stamping bending involves using upper dies at 90° for right-angle bending (standard right-angle bending). The lower dies for stamping bending have V=5~6t.
(3) How to use a bending machine?
Currently, there are various types of bending machines for sheet metal processing. They can be classified as mechanical (servo motor) or hydraulic based on the rotational method. They can also be categorized as simple manual bending machines, ordinary domestic digital positioning bending machines, and process control digital full-function bending machines based on the control system. Additionally, bending machines can have 4-axis, 8-axis, 12-axis, and other configurations.
① Before using a bending machine, check if the power supply is connected, if there is sufficient air pressure, if the hydraulic system is adequately filled, if the machine is clean, and if there are any obstacles on the slideway. Only proceed with the subsequent steps after confirming these conditions.
② Turn on the machine's power switch and initiate the oil pump to set the origin for the L-axis, D-axis, CC-axis, and Z-axis. Complete the startup process.
③ After selecting and installing the mold, set the gear switch to the "cut" position. Install the base, lower die, and upper die. Then, switch the machine to the "inch" or "single-action" mode. Use the foot pedal to raise the upper die and align it with the lower die while applying pressure. Ensure the D-axis is properly aligned and lock the lower die to complete the mold installation process.
④ Plan the bending sequence and dimensions by programming the bending machine. There are two input methods for programming: angle input and depth input. The depth input method is commonly used. Enter the bending dimensions (L, D, Z values), speed, time, number of repetitions, and other numerical values in the computer's memory. After checking and confirming the program, put the computer into operation mode. Then, perform a trial bend with scrap material to make adjustments and achieve the optimal angle and dimensions. Finally, conduct a trial bend with the actual product, and after confirming its accuracy, proceed with mass production.
⑤ To increase the bending speed during the bending process, the gear switch can be set to single-action or continuous-action mode. However, for safety reasons, it is generally sufficient to use single-action mode. When bending longer workpieces, which often have a significant angle in the middle, the CC-axis can be adjusted to achieve consistency with the angles on both sides. The principle of center bending should be observed during the bending process, as it is an important prerequisite for ensuring bending accuracy. Bending at one end of the bending machine is not allowed, as it not only affects the angle but also damages the machine.
⑥ During short breaks, it is not allowed to turn off the power supply. Turning off the oil pump is sufficient. This helps save electricity costs and avoids the need to reset the origin when starting work again, saving time and improving efficiency.
⑦ When finishing the production or at the end of the work shift, first lower the lower die to the lowest position, then turn off the oil pump, and finally turn off the power supply. If the batch of products is completed, the molds must be removed, placed back on the mold rack, and returned to the operating panel.
⑧ It is strictly prohibited to operate the bending machine in violation of regulations to avoid unnecessary harm to personnel, equipment, and molds. It is important to keep the machine clean and properly maintained, and develop good habits of caring for the equipment and molds.
(4) How to use bending molds?
Bending molds come in several types, including L-shaped, R-shaped, U-shaped, Z-shaped, and others. The upper dies have different angles such as 90°, 88°, 45°, 30°, 20°, and 15°. The lower dies include double-slot and single-slot dies with V-widths ranging from 4 to 18V. There are also R-shaped lower dies, acute angle lower dies, flattening dies, and others. The upper and lower dies can be segmented or integral. The segmented upper dies typically have lengths of 300mm, 200mm, 100mm, 100mm, 50mm, 40mm, 20mm, 15mm, and 10mm, while the integral length is 835mm. The lower dies are usually segmented into lengths of 400mm, 200mm, 100mm, 50mm, 40mm, 20mm, 15mm, and 10mm, with an integral length of 835mm.
① Bending molds are made of high-quality steel and undergo special heat treatment. They have characteristics such as high hardness, resistance to wear, and the ability to withstand high pressure. However, each set of molds has a limit pressure it can bear, expressed in tons per meter. Therefore, when using molds, it is important to select the appropriate length of the mold, which corresponds to the pressure per meter. The pressure applied must never exceed the pressure indicated on the mold.
② To prevent damage to the molds, it is specified that when setting the origin, upper and lower dies with a length of at least 300mm must be used. Only after setting the origin correctly can the same-height upper and lower dies be used. It is strictly forbidden to use segmented smaller dies to set the origin, and the origin must be set according to the standard origin pressure inside the AMADA machine.
③ When using molds, due to the varying heights of different molds, only molds with the same height can be used on a single machine. Molds with different heights should not be used together.
④ When using molds, suitable upper and lower dies should be selected based on the material hardness, thickness, and length of the sheet metal. Generally, the lower die should be used according to the standard of 5~6T, with a length slightly longer than the sheet metal. For materials with higher hardness and greater thickness, a lower die with a wider slot should be used.
⑤ When bending sharp angles or closed corners, a 30-degree upper die should be used. Sharp angles should be bent first, followed by closing the edges. When bending R angles, R-shaped upper and lower dies should be used.
⑥ When bending longer workpieces, it is best to avoid using segmented molds to reduce the marks left by the joining points. It is also preferable to use single-slot molds because the V-slot outer corner of a single-slot lower die has a larger radius, reducing the risk of bending marks.
⑦ When selecting the upper die, the parameters of all the molds should be understood. Then, based on the desired shape of the product to be formed, the appropriate upper die can be chosen.
⑧ When bending extremely hard materials or excessively thick sheets, molds should not be used to bend steel bars or other cylindrical products.
⑨ When using molds, it is important to stay focused. After the machine sets the origin, the upper and lower dies should be locked to prevent them from falling and causing harm to people or the molds. During the operation, attention should be paid to the application of pressure, avoiding applying excessive pressure at once, and monitoring the changes in the displayed data on the screen.
⑩ After using the molds, they should be promptly returned to the mold rack and placed according to the markings. The molds should be regularly cleaned of dust and coated with rust-proof oil to prevent rusting and maintain mold accuracy.
