Dimensions and Shapes
Matching of Dies Opening Dimensions
The dimensions of the V – groove or other working parts of the upper dies should be accurately matched with the corresponding accommodating or mating parts of the lower dies. For example, the angle and width of the V – groove of the upper dies should be adapted to the support angle and opening width of the lower dies to ensure that the sheet can be accurately positioned and formed during the bending process.
It is necessary to avoid situations where excessive gaps lead to a decrease in bending accuracy or too – small gaps cause increased dies wear or even prevent normal operation.
Overall Shape Adaptation
The overall shape contours of the upper and lower dies should be mutually adapted, especially in the length and width directions. They need to fit the worktable size of the press brake and the dies installation area to ensure that there is no interference after installation and that they can operate normally within the effective working range of the equipment.
At the same time, the thickness and height of the dies should also be considered to ensure that the upper dies can smoothly cooperate with the lower dies within the stroke range during the bending process to complete the bending of the sheet.
Materials and Hardness
Material Consistency
The upper and lower dies usually should be made of the same or similar materials. This is because the same materials have similar physical and mechanical properties and can maintain consistent performance when bearing bending forces, frictions, and thermal stresses, thereby avoiding problems such as uneven wear and inconsistent deformation caused by material differences.
Hardness Matching
The hardness of the upper and lower dies needs to be mutually matched. Generally, since the upper die directly acts on the sheet, it needs to have a higher hardness to ensure its wear resistance and forming accuracy. However, it should not be too hard, otherwise, it is easy to scratch the surface of the sheet.
The lower die not only needs to have sufficient hardness to support the pressure of the upper dies but also needs to consider that the hardness difference from the upper dies should not be too large to avoid excessive wear or deformation due to hardness mismatch during frequent bending processes.
Usually, the hardness of the upper dies is slightly higher than that of the lower dies, and the hardness difference between the two should be reasonably determined according to specific processing materials and process requirements.
Accuracy and Surface Quality
Consistent Machining Accuracy
The machining accuracy of the upper and lower dies should be at the same level. It includes aspects such as the dimensional accuracy, shape accuracy, and position accuracy of the dies.
For example, the angle deviation of the V – groove, straightness error, and parallelism error of the upper and lower dies should be controlled within a small range to ensure that the sheet can be bent according to the predetermined angle and shape during the bending process, meeting the accuracy requirements of the bent parts. Generally, for high – precision bending processing, the accuracy indicators of the upper and lower dies should be controlled within ±0.05mm.
Matching of Surface Roughness
The surface roughness of the upper and lower dies also needs to be mutually matched. Appropriate surface roughness can not only ensure the smooth sliding of the sheet during the bending process but also avoid damage to the sheet surface due to excessive roughness or slipping due to excessive smoothness, which affects the bending accuracy.
Strength and Stiffness
Strength Matching
Both the upper and lower dies need to withstand large bending forces during the working process, so their strengths need to be mutually matched. The upper dies needs to have sufficient strength to resist the bending stress and impact force generated during bending.
The lower dies need to withstand the pressure transmitted from the upper dies without deformation or rupture. If the strength of the upper dies is too high while that of the lower dies is insufficient, it may lead to premature damage of the lower dies; conversely, the upper dies may be bent and deformed, affecting the bending accuracy.
Stiffness Coordination
The stiffness of the upper and lower dies also needs to be coordinated. Press brake tools with insufficient stiffness are prone to elastic deformation when subjected to bending forces, which will lead to deviations in the bending angle and dimensions and affect the processing accuracy. Moreover, uneven stiffness distribution may also cause local deformation or distortion of the sheet during the bending process.
Installation and Positioning
The Same Installation Method
The installation methods of the upper and lower dies should be the same and should match the installation system of the press brake. For example, whether it is installed with dovetail grooves, T – slots, or other methods, the upper and lower dies should have the same installation interface form and size specifications.
It ensures that they can be accurately installed in the corresponding positions of the press brake, and the installation accuracy can meet the usage requirements of the dies. At the same time, the installation method should also be convenient for the quick loading, unloading, and replacement of the dies to improve production efficiency.
Ensuring Positioning Accuracy
After installation, the upper and lower dies need to be accurately positioned to ensure that their relative positions are accurate during the working process. This requires the dies to have a good positioning structure, such as positioning pins, positioning keys, etc. When installed on the press brake, through precise adjustment and fixing devices, the position deviation between the upper and lower dies can be controlled within the allowable range.
