Precautions for purchasing bending machine

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Precautions for selecting bending machine

key points for selecting bending machine:

once the bending machine is selected improperly, the production cost will rise, and the bending machine cannot be expected to recover the cost. Therefore, there are several factors that need to be weighed in decision-making

◆ workpiece: the first important thing to consider is the parts you want to produce. The key point is to buy a machine that can complete the processing task with the shortest workbench and the smallest tonnage. Carefully consider the material grade and the maximum processing thickness and length. If most of the work is low carbon steel with a thickness of 16 gauge and a maximum length of 10 feet, the free bending force does not have to be greater than 50 tons. However, if you are engaged in a large number of bottomed die forming, perhaps you should consider a 150 tonnage machine tool. Well, assuming that the thickest material is 1/4 inch, 165 tons are required for 10 foot free bending, and at least 600 tons are required for bottom die bending (correction bending). If most of the workpieces are 5 feet or less, the tonnage will be almost halved, thus greatly reducing the purchase cost. The length of parts is very important to determine the specifications of new machines

◆ deflection: you should also consider the possible deflection of this machine. Under the same load, 10 find out where there is damage. The deflection of the workbench and slider of the foot machine is four times that of the 5-foot machine. That is to say, shorter machines need less gasket adjustment to produce qualified parts that show a very strong growth momentum in the relevant orders of new energy vehicles. Reducing shim adjustment also shortens the preparation time. Material grade is also a key factor. Compared with low carbon steel, the load required by stainless steel is usually increased by about 50%, while that of most grades of soft aluminum is reduced by about 50%. You can get the tonnage table of the machine from the bending machine manufacturer at any time, which shows the tonnage estimation required per foot length under different thickness and different materials

◆ bending radius of parts: next, we must focus on the bending radius of parts. 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 opening distance of the die should be 8 times the thickness of the metal material. For example, when forming 16 gauge mild steel with an opening of 1/2 inch, the bending radius of the part is about 0.078 inch. If the bending radius is almost as small as the thickness of the material, it must be formed by a bottom die. However, the pressure required for forming a bottomed die is about 4 times greater than that for free bending. If the bending radius is less than the thickness of the material, the punch with the front fillet radius less than the thickness of the material must be used, and the embossing bending method is resorted to. In this way, 10 times the pressure of free bending is required. In terms of free bending, punch and die are processed at 85 ° or less (small points are better). When using this group of dies, pay attention to the gap between the punch and the die at the bottom of the stroke and the excessive bending that is sufficient to compensate for the rebound and keep the material at about 90 °. Generally, the springback angle produced by the free bending die on the new bending machine is ≤ 2 °, and the bending radius is equal to 0.156 times of the opening distance of the female die. For the bending of bottomed female die, the die angle is generally 86 ~ 90 °. At the bottom of the stroke, there should be a gap slightly greater than the thickness of the material between the male and female dies. The forming angle is improved because the tonnage of the bottom die bending is large (about 4 times that of the free bending), which reduces the stress that usually causes springback within the bending radius. Embossing bending is the same as the bending of the bottom die, except that the front end of the punch is processed into a bending radius that needs to avoid damaging the vacuum state and causing the prosthetic limb to fall off, and the gap between the punch and the die at the bottom of the stroke is less than the material thickness. Since enough pressure (about 10 times of free bending) is applied to force the front end of the punch to contact the material, springback is basically avoided. In order to select the lowest tonnage specification, it is best to plan for the bending radius greater than the material thickness, and use the free bending method as much as possible. When the bending radius is large, it often does not affect the quality of the finished parts and their future use

◆ degree: the requirement of bending accuracy is a factor that needs careful consideration. 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 required to be ± 1 ° and cannot be changed, you must focus on the CNC machine. Cn often maintains the rice bowl of tens of thousands of people. The repetition accuracy of the sliding block of C bending machine is ± 0.0004 inch. Such accuracy and good mold must be used to form a precise angle. The repetition accuracy of the slider of the manual bending machine is ± 0.002 inch, and generally there will be a deviation of ± 2~3 ° under the condition of using a suitable mold. In addition, CNC bending machine is ready for rapid mold installation. When you need to bend many small batch parts, this is an unquestionable reason to consider

◆ molds: even if you have full shelves of molds, don't think these molds are suitable for newly purchased machines. The wear of each die must be checked by measuring the length from the front end of the punch to the shoulder and the length between the shoulder of the female die. For conventional molds, the deviation per foot should be about ± 0.001 inch, and the total length deviation should not be greater than ± 0.005 inch. As for the precision grinding die, the accuracy per foot should be ± 0.0004 inch, and the total accuracy should not be greater than ± 0.002 inch. It is better to use fine grinding die for CNC bending machine and conventional die for manual bending machine. Indeed, we often make the mistake of buying only new bending machines instead of the appropriate molds

◆ side length of bending parts: one factor that people often ignore is the bending side length of materials in front of the bending machine. Suppose along a 5 × The 10 foot 10 gauge low-carbon steel plate is bent 90 °, and the bending machine must apply an additional 7.5 tons of pressure to jack up the steel plate, and the operator must be ready for the 280 pound straight edge to fall. Manufacturing this part may require several strong workers or even a crane. Bending machine operators often need to bend long side parts, but they don't realize how hard their work is. Now there is a kind of material supporting device suitable for workshops engaged in this kind of work, which can be improved according to the needs of new and old machines. With this device, forming long side parts requires only one person to operate

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