CNC bending machine purchase knowledge: the first important thing to consider is that you want to produce parts, the point is to buy a machine to complete the processing task and the shortest working table, the smallest tonnage of the machine.
Carefully consider material grade and maximum machining thickness and length. If the bulk of the work is made of mild steel with a thickness of 16 gauge and a maximum length of 10 feet, then the free bending force need not be greater than 50 tons. However, if you are engaged in a large number of die forming with a bottom, you may want to consider a 150 ton machine tool cnc press brake.
Ok, assuming the thickest material is 1/4 inch, it would take 165 tons for a 10 foot free bend and at least 600 tons for a die bend (corrected bend). If the bulk of the work is 5 feet or less, the tonnage is nearly halved, thus greatly reducing the acquisition cost. The length of the parts is very important in determining the specification of a new machine.
Under the same load, the 10 - foot machine table and slider appear 4 times more torsion than 5 - foot machine. This means that shorter machines require less gasket adjustment to produce qualified parts. Reduced gasket adjustment reduces preparation time. Material grade is also a key factor. Compared with mild steel, stainless steel usually requires about 50% more load, while most grades of soft aluminum require about 50% less load. You can always get a tonnage table for the machine from the bending machine manufacturer, which shows the estimated tonnage per foot length for different thicknesses and materials.
The bending radius of the part
When free bending is adopted, the bending radius is 0.156 times of the opening distance of the die. In the free bending process, the die opening distance should be 8 times the thickness of the metal material. For example, when forming a 16 Gauge low carbon steel with a 1/2 inch opening distance, the bending radius of the part is about 0.078 inches. If the bending radius is almost small to the thickness of the material, the bottom die must be formed. However, die forming with a bottom requires about four times more pressure than free bending.
If the bending radius is less than the thickness of the material, must use the front end of the fillet radius is less than the thickness of the punch, and resort to the imprint bending method. In this case, 10 times the free bending pressure is required.
For free bending, punch and die are machined to 85° or less (smaller is preferred). When using this set of dies, pay attention to the gap between the punch and die at the bottom of the stroke and to excessive bending enough to compensate for springback to keep the material at about 90°.
Usually, the free bending die in the new bending machine produced rebound Angle is less than 2°, bending radius is equal to 0.156 times the opening distance of the die.
For bending die with bottom, the mold Angle is generally 86 ~ 90°. At the bottom of the stroke, there should be a gap between the convex and concave dies slightly greater than the thickness of the material. The forming Angle is improved because the tonnage of the bottom die bending is larger (about 4 times that of free bending), reducing the stress that normally causes springback within the bending radius.
Embossing bending is the same as the bottom die bending, but the front end of the punch is processed into the required bending radius, and the bottom of the stroke of the die gap is less than the thickness of the material. Springback is largely avoided by applying enough pressure (about 10 times that of free bending) to force the punch's front end into contact with the material.
In order to choose the lowest tonnage specifications, it is best to be greater than the thickness of the bending radius of the material, and as far as possible to use the free bending method. When the bending radius is large, it often does not affect the quality of the finished parts and its future use.
Bending accuracy is a factor that needs to be carefully considered, and it is this factor that determines whether you need to consider a CNC bending machine or a manual bending machine. If the bending accuracy is ±1° and cannot be changed, you must look at a CNC machine.
CNC bending machine sliders repeat accuracy of ±0.0004 inches, forming accurate Angle must use such accuracy and good die. The slider repeatability of the manual bending machine is ±0.002 in., and will generally produce a deviation of ±2 to 3° when using the right mold. In addition, CNC bending machines are ready for quick mold mounting, an undeniable consideration when you need to bend many small batches of parts.
Even if you have a shelf full of molds, do not assume that these molds are suitable for a new machine. Each die must be checked for wear by measuring the length of the punch front to the shoulder and the length between the die shoulder.
For conventional molds, the deviation should be about ±0.001 inches per foot and not greater than ±0.005 inches for total length. For fine grinding dies, accuracy per foot shall be ±0.0004 inches and total accuracy shall not be greater than ±0.002 inches. It is best to use fine grinding dies for CNC bending machines and conventional dies for manual bending machines.
Length of bending part side
Assuming a 90-degree bend along a 5-by-10-gauge low carbon steel plate, the bending machine would have to apply approximately 7.5 tons of additional pressure to lift the plate, and the operator would have to prepare for a 280-pound straight drop. It may take several able-bodied workers or even a crane to make the part. Bender operators often need to bend long-sided parts without realizing how hard their job is.
There is now a feeding device suitable for the workshop where this work is carried out, which can be modified according to the needs of old and new machines. By using the device, forming long side parts only needs one person to operate.
The CNC system of bending machine generally uses E200 DA41 DA51 DA53 DA56 DA65 DA66
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