Determination of the length and width of the die for U-shaped bends
Determining the length and width of the die for U-shaped bends is crucial for ensuring part precision and mold life. This requires comprehensive consideration of multiple factors, including the part’s geometric parameters, material properties, and production process. First, the die length must be determined based on the part’s unfolded length, while allowing for sufficient overlap to prevent the sheet metal from shifting during the bending process. For typical U-shaped parts, the die length is typically the sum of the two straight sides plus the unfolded length of the bend radius, with an additional 10-20mm overlap allowance. This ensures full material utilization while preventing workpiece deformation due to insufficient overlap. Furthermore, the die’s guiding structure must be considered. If guide pins and sleeves are used, the die length must also accommodate the installation space required for the guide components to ensure mold stability during operation.
The determination of the die width is related to the width of the part being bent and the material flow during the bending process. Typically, the die width should be slightly larger than the part’s width, typically 1.1-1.2 times the width. This is because during the bending process, the material undergoes a certain amount of lateral expansion due to plastic deformation. If the die width is too small, the material may be squeezed laterally, resulting in wrinkles or cracks. If the die width is too large, the material positioning may be inaccurate, affecting the dimensional accuracy of the part. The die width also needs to consider the overall structural layout of the mold. For example, mounting bolts, pins, and other components on both sides of the die require a certain amount of space. Therefore, these factors must be factored into the calculation when determining the width to ensure proper mold assembly.
In actual production, the length and width of the die must be adjusted according to the material thickness. For thicker materials, due to the greater springback during bending, the die length and width should be increased to compensate for the dimensional deviation caused by springback. For thinner materials, due to their greater plasticity and less springback, the die size can be reduced to improve material utilization. Furthermore, the precision requirements of the bent part will also influence the determination of the die size. When the bent part requires higher dimensional accuracy, the die length and width must be calculated using more precise methods, and corrections should be made through trial molds as necessary to ensure the workpiece meets the design requirements.
The length and width of the die must also be determined based on the die’s strength and service life. The die is subject to significant impact and friction during the bending process, so its dimensions must ensure sufficient strength and rigidity to prevent deformation or damage during use. For example, the die should not be too short, as this will cause stress concentration and reduce the die’s service life. The die’s width must also be appropriately designed based on the bending forces to ensure it can withstand the lateral forces generated by material deformation. Furthermore, the die’s dimensions should be easy to manufacture and maintain. While meeting operational requirements, standardized dimensions should be used whenever possible to reduce production costs.
In short, determining the length and width of the die for a U-shaped bend is a comprehensive process, requiring analysis and calculation based on multiple factors, including the part’s structural characteristics, material properties, production process, and mold strength requirements. In practice, designers should flexibly adjust the die dimensions based on specific circumstances, optimizing them through simulation or trial mold verification when necessary to ensure part quality and mold reliability, thereby improving production efficiency and economic benefits.
