During the use of the bending machine, the demand for Press Brake Tools is very large, and the precision requirements for the bending machine tools are also very high because if its accuracy is low, it will have a lot of impact on the product, For example, sheet metal bending angle deviation, sheet metal rebound angle, deformation of the bent workpiece, and reduction of tools life, etc. So which materials are suitable for making tools? In today’s article, the following is a brief introduction to the bending machine tools from several aspects.
- Intensification: the centralized integration of commodity varieties, services and other functions in the bending machine tools mall. A good professional market can not only achieve a high concentration of commodities and ensure that buyers can buy the products they need in the market, but also meet the needs of customers to achieve “one-stop” procurement through scientific and reasonable girl design.
- Specialization: Do a good job of writing on specific words. China’s bending machine tools industry is divided into metal stamping toolss, injection toolss and many other doors.
- Scale: Not only is the market size, building area and other hardware indicators reflected, but more importantly, the concentration of brands, products, manufacturing plants, and traders in the market.
- Informatization: It is necessary to give full play to the role of information technology in competition, and extend the competition of a single product to the entire supply chain.
- Internationalization: The circulation of press brake tools products must be further internationalized, showing the situation of the internationalization of the domestic market and the domesticization of the international market. A modern bending machine tools city should have the business and ability to operate internationally. In terms of hardware, it must provide a venue for buying one activity, and in terms of software, it must provide full-process services for international sweaters.
The influence of the low precision of the press brake tools on the product:
For some products with low precision requirements, the precision requirements can be relaxed; but for precision tools such as bending machine tools, the accuracy directly determines whether it is of high quality. So if the tool’s precision is not high, what impact will it have on the product? Let’s take a look:
- Sheet metal bending angle deviation
If the angle of the bending knife is too large or too small, it will directly cause the angle of the finished sheet metal product to fail to meet expectations. And if the edge of the bending knife is not straight enough, it will also lead to a larger arc at the bend of the finished sheet metal, rather than an obvious angle. May affect the quality of the workpiece.
If the precision of the groove chamfering mouth of the lower die is not high, and the angle is too large, it will cause the sheet metal to slide down during bending, resulting in deformation or large bending at the bend. If the angle is too small, it is easy to leave an indentation at the end of the sheet metal, which affects the quality and appearance of the workpiece.
- Sheet metal rebound angle
The accuracy of the chamfering angle of the lower die of the bending machine is not high. For example, when the angle is too small or too large, the depth of the sheet metal pressing is too different. This is because the rebound angle of the sheet metal will be different from the estimated value, which will affect the quality of the product.
- Deformation of the bent workpiece
Some bending machine tools will consider a concept called cavity at the beginning of the design, and its function is to avoid the product. , contact with the cavity part, resulting in the deformation of the upper part of the workpiece.
- The life of the tools is shortened
The low precision of each part of the bending machine tools will affect its life. For example, the angle deviation of the upper and lower die will increase the friction. The low precision of the die handle leads to the deviation of the overall parallelism and increases the friction in a certain direction of the upper and lower corners. The low precision of the tools slot may cause the tools to wobble. The wobble during operation not only shortens the life of the tools but also greatly affects the work efficiency.
Materials suitable for bending machine tools:
So what kind of materials are suitable for the manufacture of bending machine tools? Different materials are used in different production fields. Here, the editor will cite several commonly used materials to compare their advantages and disadvantages.
- High carbon structural steel
Low elasticity, low hardenability after heat treatment, hardness can generally reach HRC30-35 degrees, generally suitable for ordinary bending machine tools, the main representative of which is No. 85 steel, its strength and hardness are higher than other 75/70/80 The steel is slightly higher, so for workpieces with low bending requirements, No. 85 steel can basically meet the requirements.
- Low carbon alloy steel
Generally, the hardness and toughness of low carbon alloy steel are much stronger than that of high carbon steel. This is due to the addition of trace metal elements such as chromium and molybdenum in the smelting process, and its performance is greatly improved.
- 42CrMo steel
It is low-carbon alloy steel with very good performance. After heat treatment, the hardness can reach HRC48±2 degrees. It can be well adapted to the production of various high-precision and strict-standard bending machine tools with strong wear resistance. Now, 42CrMo is used at home and abroad. is more common and has a wide range of applications.
- Cr12MoV steel
It is also low-carbon alloy steel, which is more widely used in stamping dies. Because of its high hardness, high wear resistance, and high hardenability, it is well used in blanking dies. With the development of industry, this kind of steel has also been gradually put into the production of bending machine tools. After heat treatment, the hardness is HRC55-60 degrees. Its high hardness and high wear resistance determine that Cr12MoV steel has a good application in special fields.
The 6 parameters of the press brake dies are introduced as follows:
- Bending machine die material: The material is generally T8 or T10, and the better 42CrMo material is used. It mainly requires high strength, high toughness and good wear resistance, so choose cold die steel. Cr12MoV is a good material. The use performance is satisfactory, the process performance is also very good, and the price is also high.
- Quenching and hardening temperature: fifty-two to sixty degrees Celsius.
- Allowable tolerance: 0.02 mm.
- Standard length: 835 mm, 800 mm, 550 mm (standard NC press brake tools product specifications, non-standard press brake tools specifications can be customized for processing and production according to the drawings provided by customers).
- The die segment specifications are as follows: the upper die of die segment 1 is 100 (left), 10, 15, 20, 40, 50, 200, 300, 100 (right) = 835 mm; the lower die is 10, 15, 20, 40, 50, 100, 200, 400=835mm. The upper tools of tools segment 2 is 100 (left), 10, 15, 20, 40, 50, 165, 300, 100 (right) = 800 mm. It is suitable for imported L.V.D bending machine, AMADA bending machine, TRUMPF, FINN-POWER and other NC bending machine tools and toolss for domestic NC bending machine. The products include CNC bending machine step type, bending machine concentric lower type, bending machine upper type, and bending machine lower type.
- Standard tool: The press brake die is divided into the upper die and the lower die of the press brake, which are used for sheet metal stamping and separation. The tools for forming has a cavity, and the tools for separation has a tip.
How to choose the tools of the CNC bending machine？ we can analyze it from the upper tools and the lower tools:
- Selection of upper die of CNC bending machine
The selection of the upper die should be determined according to the size of the bending force. Note that the load of the die should not exceed the limit. If the user chooses a special die, special attention should be paid to the load of these dies which is different from the normal die. It is necessary to correctly select the upper die of the CNC bending machine to prevent the upper die from cracking and hurting people due to the bending force exceeding the load limit of the upper die.
The shape of the upper die of the CNC bending machine has a great influence on whether the workpiece can be bent and formed. When programming and selecting the die, it is necessary to consider the shape of the die and whether it interferes during the forming process of the workpiece.
When the tools are programmed into the tools library of the CNC system, the outer dimensions of the tools must be programmed accurately, and the CNC system can accurately calculate whether the tools interfere with the workpiece when it automatically calculates the bending process.
- Selection of the lower die of the CNC bending machine
The width of the V-shaped lower dies V must be determined according to the following formula according to the thickness t of the material. The general formula is:
t < 3mm V =(6～8)×t
t ≥ 3mm V =(8～12)×t
The width of the lower dies V can also be determined reasonably and scientifically according to the change of the small bending width b and the fillet radius r of the bending part.
The bending force generated by the CNC bending machine during the bending process will gather on the work table and also act on the tools, so it should be noted that the load on the tools cannot exceed the limit.
If the user uses a new CNC press brake, all aspects of the standard CNC hydraulic press brake are very good. When bending the sheet metal part on the press brake with the new die, the part also meets the drawing requirements. But after a period of production, it will be found that the workpiece bent from the same tools does not meet the requirements of the drawing. Why?
Cause analysis: wear of the upper die
The upper bending die is generally an all-purpose die, and a set of general bending die can meet the bending requirements of a series of sheet metal parts. In addition, upper dies are also frequently used. In other words, we have fewer upper dies for metal stamping machines. According to HARSLE’s surveys and visits to customers who use CNC bending machines, some small factory production units never change the upper die of the bending machine.
In addition, the R angle of the upper bending die is relatively small, generally less than R0.5mm. When bending, the pressure is concentrated on the R corner of the upper die. The stress at the R corner is large. Therefore, the upper bending die is easily worn.
Wear on the upper die causes the R angle to increase. In the calculation of the workpiece series data, the size of the bending R angle is one of the factors affecting the expansion coefficient of the workpiece. Therefore, users often complain that the size of the workpieces produced by the CNC bending machine increases after long-term use. In this case, in fact, the problem is not the responsibility of the manufacturer, it is caused by the customer’s natural wear and tear or improper use.
Optional Press Brake Tools
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