Hydraulic bending machine and CNC bending machine purchase notice

Choose a few problems to consider bending machine

Hydraulic bending machine and CNC bending machine equipment in its processing field and the nature of the process is different, because as a manufacturer in the purchase of bending machine as a comprehensive consideration. It is best to consider carefully what to buy from the end-use of the machine, the known bending variables that the machine can have, the bending radius of the parts, and so on. Therefore, as the decision maker, you have the responsibility to understand the performance of the equipment in detail, processing range, processing function, processing accuracy and so on. This responsibility is serious, once improper choice, your production costs will climb, bending machine can not be expected to recover costs. Therefore, several factors need to be weighed in decision making

artifacts

The first important consideration is the parts you are going to produce. The point is to buy a machine that can complete the processing tasks with the shortest worktable and the smallest tonnage. Carefully consider the material grade and the maximum machining thickness and length. If most of the products produced are mild steel with thickness up to 3mm and maximum length up to 2500mm, the free bending force need not be greater than 80 tons. However, if engaged in a large number of concave die forming may consider a 150 tonnage or so machine tool. If in production to bend the thickest material has 6mm, length 2500mm low carbon steel free bending, then it is necessary to consider the need for 100 tons of bending machine. If some bending with bottom die bending forming (correction bending), then the larger tonnage of the bending machine. If most of the bending workpiece is 1250mm or shorter, then consider the bending machine tonnage is almost half, so as to greatly reduce the purchase cost. Therefore, the length of processed parts products is very important to determine the specifications of new models.

Flexible change

Bending machine in bending processing, especially bending long size of the workpiece, there will certainly be flexible parts the longer the greater the degree of flexibility. Under the same load, the torsion of the table and slider of the 2500mm model is 4 times that of the 1250mm model. This means that shorter machines require fewer shim adjustments and can produce qualified parts, reducing shim adjustments and shortening the lead time. But now the NUMERICAL control hydraulic bending machine in the production design have increased the hydraulic deflection compensation function, reduce the production operator to adjust the equipment, and improve the bending accuracy and production efficiency. The hydraulic deflection compensation function is controlled by the NUMERICAL control system, and the hydraulic oil enters the compensation cylinder through the magnetic valve to push the worktable upward. At the same time, the deflection compensation force increases with the increase of bending force, which plays a deflection compensation role. The material of the machined material is also a key factor. Compared with low carbon steel, stainless steel needs a load usually increased by about 50%, and most materials for soft aluminum side reduced by about 50%. Standard bending pressure parameters can be obtained from the manufacturer of the bending machine. This table shows the bending force required per 1000mm length for different thicknesses and materials.

The bending radius of the part

The bending radius of the workpiece is also a factor to be considered in the process of bending products. When free bending is used, the bending radius is 0.156 times of the opening size of V slot. During free bending, the opening size of v-groove should be 8 times the thickness of metal material. For example, when bending 1.5mm mild steel with a 12mm v-slot opening size, the bending radius of the part is approximately R=1.9mm. If the bending radius is close to the thickness of the material or less than the thickness of the plate, it must be formed with the bottom concave die. However, the pressure required to form with a concave die is about four times greater than that required for free bending. For free bending, note the gap between the upper die and the lower die at the bottom of the stroke and the excessive bending sufficient to compensate for springback and keep the material around 90°. Usually, the springback Angle of the free bending die on the new bending machine is less than or equal to 2°, and the bending radius is equal to 0.156 times of the opening distance of the lower die. Therefore, the bending process is generally free up and down the mold, and the mold 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 upper and lower molds. The forming Angle is improved because the larger tonnage bending with the bottom die (approximately 4 times that of free bending) reduces the stress within the bending radius that normally causes springback. Embossing bending is the same as bending with bottom concave die, but the front end of the die is processed into the required bending radius, and the gap between the bottom end of the stroke is less than the thickness of the material. Springback is basically avoided by applying enough pressure (approximately 10 times that of free bending) to force the front end of the upper die to contact the material. In order to select the lowest tonnage specification, it is best to plan for a bending radius greater than the thickness of the material and to use free bending whenever possible. When the bending radius is large, it usually does not affect the quality of the parts and their future use.

precision

The bending accuracy requirement is a factor that needs to be considered carefully. It is this factor that determines whether you need to consider a CNC bending machine or an ordinary NC bending machine. If the bending accuracy is required within ±0.5° and cannot be changed, you must look at CNC bending machines. CNC bending machine slider repetition accuracy is generally guaranteed in ±0.01mm, forming accurate Angle must use such precision and good mold. NC bending machine slider repetition accuracy of ±0.5mm, and in the use of appropriate mold conditions will generally produce ±2~3° of deviation. In addition, CNC bending machines are equipped with fast analog digital control system and clamping fixture when you need to bend many small batch parts, this is an indisputable reason to consider.

The mould

Bending mold is also directly affect the bending accuracy, so to check the mold wear degree of the mold, the method is to measure the length of the front end of the mold to the shoulder and the length between the shoulder of the mold. For conventional molds, the deviation should be ±0.01mm or so per 10mm, and the total length deviation should not be greater than ±0.15mm. As for the fine grinding mould, the accuracy should be ±0.005mm per 100mm, and the total accuracy should not be greater than ±0.05mm. It is best to use fine grinding die for NC bending machine and conventional die for NC bending machine.