Problems that should be paid attention to when buying a CNC bending machine

Views: 9     Author: DURMAPRESS     Publish Time: 2020-11-18      Origin: DURMAPRESS


Problems that should be paid attention to when buying a CNC bending machine

Problems that should be paid attention to when purchasing a CNC bending machine:

Once an improper selection is made when purchasing a bending press machine, the production cost will rise, and the bending machine cannot be expected to recover the cost. Therefore, choosing a good product is the first choice. The wc67y hydraulic press brake produced by Maanshan Durmapress Machinery Techology Co.,Ltd is mainly used for production, with excellent quality and after-sales guarantee. When choosing a bending machine, there are several factors that must be considered in the decision-making process:


1. Workpiece

    The first important thing to consider is the parts you want to produce. The point is to buy a durmapress hydraulic press brake 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 (3.048 meters), then the free bending force does not need to be greater than 50 tons. However, if you are engaged in a large number of bottomed die forming, perhaps a 160-ton machine tool should be considered.

    Assuming that the thickest material is 1/4 inch, a 10-foot free bending requires 200 tons, and a bottomed die bending (correction bending) requires at least 600 tons. If most parts are 5 feet or shorter, the tonnage is almost halved, which greatly reduces the cost of purchase. The length of the part is very important for determining the specifications of the new machine.

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2. Torsion

    Under the same load, the deflection of the worktable and sliding block of the 10-foot machine is 4 times that of the 5-foot machine. This means that shorter machines require fewer shim adjustments to produce qualified parts. Reduced shim adjustment and shortened preparation time.

    Material grade is also a key factor. Compared with low-carbon steel, the load required for stainless steel is usually increased by about 50%, while most grades of soft aluminum are reduced by about 50%. You can get the machine's tonnage table from the bending press machine manufacturer at any time. The table shows the estimated tonnage required per foot in different thicknesses and different materials.


3, bending radius

When free bending is used, the bending radius is 0.156 times the die opening distance. During the free bending process, the opening distance of the die should be 8 times the thickness of the metal material. For example, when using 1/2 inch (0.0127 m) opening distance to form 16 gauge low carbon steel, the bending radius of the part is about 0.078 inches. If the bending radius is almost as small as the thickness of the material, a bottomed die must be formed. However, the pressure required for forming a bottomed die is about 4 times greater than that of free bending. If the bending radius is smaller than the thickness of the material, a punch with a front-end fillet radius smaller than the thickness of the material must be used and the imprint bending method must be used. In this way, 10 times the pressure of free bending is required.

As far as free bending is concerned, punch and die are processed at 85° or less (smaller is better). When using this set of molds, pay attention to the gap between the male mold and the female mold at the bottom of the stroke, and the excessive bending that is sufficient to compensate for the springback and keep the material at about 90°. Generally, the springback angle of the free bending die on the new bending press machine is ≤2°, and the bending radius is equal to 0.156 times the opening distance of the die.


For the bending of bottomed concave molds, the mold angle is generally 86 ~ 90°. At the bottom of the stroke, there should be a gap slightly larger than the thickness of the material between the male and female molds. The forming angle is improved because the bottomed die has a larger bending tonnage (about 4 times that of free bending), which reduces the stress that usually causes springback in the bending radius.

The imprint bending is the same as the bending of the bottomed die, except that the front end of the punch is processed to the required bending radius, and the gap between the punch and the die at the bottom of the stroke is smaller than the material thickness. Since enough pressure (approximately 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 choose the lowest tonnage specification, it is best to plan for a bending radius larger 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 part and its future use.


4, curvature

Bending accuracy requirements are a factor that needs to be carefully considered. It is this factor that determines the need to consider a CNC wc67y hydraulic press brake or a durmapress hydraulic press brake. If the bending accuracy is required to be ±1° and cannot be changed, the CNC machine must be focused.

The repeatability of the slider of the CNC bending machine is ±0.0004 inches, and the precise angle of forming must use such precision and a good mold. The repeatability of the slide block of the manual bending machine is ±0.002 inches, and the deviation of ±2~3° is generally produced under the condition of using a suitable mold. In addition, the CNC bending machine is ready for rapid mold assembly. When many small batches of parts need to be bent, this is an indisputable reason for consideration.

5, mold

Even if there are shelves full of molds, don't assume that these molds are suitable for newly purchased machines. Must check accessories

The wear of the mold is measured by measuring the length from the front end of the punch to the shoulder and the length between the shoulder of the female mold. For conventional molds, the deviation per foot should be about ±0.001 inches, and the total length deviation should not be greater than ±0.005 inches. As for the precision grinding mold, the accuracy per foot should be ±0.0004 inches, and the total accuracy should not be greater than ±0.002 inches. It is best to use fine grinding molds for CNC bending machines, and conventional molds for manual bending machines.

6, the side length of the bent part

Assuming that it is bent 90° along a 5×10-foot 10-gauge low-carbon steel plate, the bending machine must apply an additional 7.5 tons of pressure to lift the steel plate up, and the operator must prepare for the 280-pound straight edge drop . It may require several strong workers or even a crane to manufacture this part. Operators of bending machines often need to bend long-side parts without realizing how strenuous their work is.

What type of parts to produce, then you should choose a bending machine suitable for this type of part. It is best to be precise, so that while the cost can be well controlled, it can also be technically improved. Of course, this It also includes the choice of model, such as: what thickness of parts you produce, then the choice of bending machine should also choose a suitable model.

If it is a relatively short bending machine, it is best to be able to order some gaskets, so that qualified parts can be made better. This is a common sense, and it can also shorten the time and increase the output. In addition, if free bending is used, generally speaking, the bending radius at this time is 0.156 times. This is a common sense. It should be noted that usually, when the free bending mold is applied to a new bending machine, it will generally produce Bouncing angle less than 2 degrees.

Special attention should be paid to the problem of curvature, which can directly affect production problems. For example, if the curvature is required to be greater than or less than 1, then CNC bending machines should be used. Pay attention to the mold. Generally speaking, the deviation range of the conventional mold must be reduced. Generally, it is about 0,001 inches and cannot be too large. If it is a fine grinding mold, the deviation is about 0.0004 inches. All of the above It is an introduction to the selection of bending machines, which can be said to be more complicated, if you do not understand this aspect.

How to choose and buy a suitable CNC bending machine mainly needs to consider the following factors:

①Calculate how many tons of CNC bending machine need to be purchased according to the material and thickness of the metal sheet to be processed and bent. The tonnage here refers to the maximum pressure of the bending machine, not the weight of the CNC bending machine;

②The width of the knife edge of the bending machine (determined according to the length of the plate), the depth of the throat and the distance between the columns;

③Whether to choose an electro-hydraulic synchronous CNC bending machine or a torsion axis synchronous bending machine is also a problem to be considered. The electro-hydraulic synchronous type of bending machine can be more intelligent and fully automated, but the price is higher, and the torsion axis synchronous type of bending Machine price is cheap;

④ There are many types of electro-hydraulic synchronous bending machines, which can be customized according to the requirements of the workpiece, such as the number of axes, compensation type, laser test, safety protection (laser protection or light curtain protection), etc.

When choosing a good bending machine, you also need to consider what kind of mold to use

1. If you want to choose the appropriate bending machine mold for the bending machine equipment, you must first have a global grasp of the type of the bending machine. What you need to know is the brand, size, and actual tonnage of the bending machine. Once you are familiar with these factors, you can use these data as a factual basis when selecting a mold.

2. If you encounter the bending machine due to the long service life, the brand is blurred and unclear, it is recommended to send the sample of the bending machine mold to the manufacturer to customize it according to the specifications.

3. If the use of combined molds for bending machines is involved in production, the matching degree between the upper and lower molds is usually higher. If the matching is not in place, the results produced by the workpiece after the bending procedure may not meet the production quality specifications and requirements.

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