In the process of implementing the transformation project of scientific and technological achievements, our company has developed a new type of high-strength nano cement fire-proof safety box according to the requirements of customers.
The inner container and outer shell parts of the safety box are bent with cold-rolled steel plates.
How to make the press brake machine smoothly complete the bending of U-shaped parts without interference is the key to solving the process problem.
1. Process analysis of parts
As shown in Fig. 1 and Fig. 2, they are the inner container diagram and the outer shell diagram of the safety box respectively.
Fig. 1 Inner container Fig. 2 Outer shell
The part is made of 3mm cold-rolled steel plate and needs to be bent on the press brake machine.
When demonstrating the bending simulation of the part model, one side of the part interferes with the panel of the press brake machine.
After analysis, we think that the aspect ratio of the part is too large, reaching 1.54 and 1.52 respectively, which are far more than 1:1.
On the ordinary bending die, when bending U-shaped parts, the maximum length-width ratio should not exceed 1:1, otherwise, the long side of the part will interfere with the press brake machine, as shown in Figure 3.
Fig. 3 Interference phenomenon of long side of the part
2. Structure of existing press brake machine
We analyzed the press brake machine and bending die:
The front panel of the press brake machine is shaped, and the structure is huge and complex, with a thickness of about 80mm, which is fixed.
When bending, the worktable of the press brake machine and the bending die move up and down together.
It is unreasonable and impossible to adapt to parts processing with the improved press brake machine.
Taking appropriate design improvement to the bending die can achieve twice the result with half the effort, and then complete the bending of U-shaped parts without changing the structure of the press brake machine.
The ordinary bending die is a left-right symmetrical structure with 45°, as shown in Figure 4.
Fig. 4 The ordinary bending die
The trajectory of the die is equivalent to the diagonal of a square.
The maximum length-width ratio of the U-shaped part that can be folded by the die is 1:1.
If it exceeds this range, one side of the part will interfere with the press brake machine, and the processing of the part cannot be completed.
3. Solutions of interference between parts and press brake machine
Through the analysis of the process of the parts and the structure of the cutter die of the press brake machine, it can be seen that the cause of the interference is that the length-width ratio of the U-shaped parts is too large, which is beyond the bending range of the cutter die of the press brake machine.
To solve this problem, we must change the left and right symmetrical structure of the traditional ordinary bending die.
Therefore, we made a bold exploration and adopted the left-right asymmetric structure.
To analyze the part in plan view:
In the plane figure (see Fig. 5), the U-shaped part is considered as a rectangle.
The point A is translated 40 mm (≤half of the thickness of the press brake machine panel 80 mm) to the point B.
The diagonal line between the point B and the point C divides the right angle into two parts, 30° and 60°, respectively.
According to this data, we made the bending upper and lower die, as shown in Fig. 6.
The long side of the U-shaped part avoids the press brake machine panel, thus increasing the processing range of the press brake machine.
Fig. 5 The plane figure
Fig. 6 The bending upper and lower die
4. Bending die improvement
For the above-mentioned parts and press brake machine interference problems, we made improvements for two different press brake machine:
The first is to improve on the ordinary press brake machine, using the original bending die as a benchmark, the lower die as a fixed base, the newly made asymmetric lower die fixed on it, and then directly replace the upper die, as shown in Figure 7.
Fig. 7 Improvement on the ordinary press brake machine
The second is to improve on the CNC press brake machine by adding an adjustable lower die holder connected to the base of the press brake machine, and the upper die is directly replaced, as shown in Figure 8.
Fig. 8 Improvement on the CNC press brake machine
In the die adjustment, it is different from the left and right symmetrical ordinary die.
The ordinary die only needs to be adjusted to the thickness of the bent parts with the tip points of the upper and lower dies as the benchmark;
But for this kind of asymmetrical die, the spacing between the upper and lower dies should be used as the adjustment standard instead of aligning the points of the upper and lower dies as the benchmark.
It needs to first adjust the spacing between the upper and lower dies to the left and right equal, and then adjust to the thickness of the bent parts can be.
This is directly on the original bending die transformation, can achieve lower manufacturing costs, short production cycle, easy to operate, to achieve twice the result with half the effort.
Through the improvement of the bending tool, the interference problem of U-shaped parts in the bending process is solved, and the processing range of the press brake machine is increased.
In the processing, the operation is simple and easy to use.
For different U-shaped parts, the left and right angles of the bending tool can also be recombined to solve the purpose of interference, which is very valuable for promotion.