In the metal fabrication industry, bending is a crucial process that shapes metal sheets into desired configurations. The precision of this shaping largely depends on the type of bending tool dies used. These dies are categorized into standard and special molds, each suited for different bending tasks and metal thicknesses. This guide will explore the nuances of selecting and utilizing these tool dies, ensuring that fabricators can achieve optimal results with every bend.
Understanding Bending Tool Dies
1. Standard vs. Special Bending Molds
- Standard Molds: Used for common bending operations such as right-angle and simple non-right-angle bends. These dies are designed to handle a wide range of typical bending tasks efficiently.
- Special Molds: Employed for bending unique structural components like stepped bends, dead edges, or other complex forms. These require customized dies to accommodate specific design requirements.
Selecting the Right "V" Groove Size
Choosing the correct "V" groove size for the lower die is critical and varies with the thickness of the sheet metal:
- General Rule: The opening size of the "V" shaped groove should be 6-10 times the thickness of the material.
- 0.5 to 2.6 mm thick: 6 times the thickness.
- 3 to 8 mm thick: 8 times the thickness.
- 9 to 10 mm thick: 10 times the thickness.
- Above 12 mm thick: 12 times the thickness.
For thinner materials, smaller multipliers are preferable to reduce the risk of cracking or over-bending. Conversely, thicker materials require larger grooves to accommodate the increased material volume during bending.
Bending Size Calculation Methods
Calculating the correct bending size is essential for precision in fabrication. The bending coefficient varies depending on the angle of the bend and the material thickness:
- Less than 45 Degrees Bend:
- Coefficient = Material Thickness 0.35 due to higher deformation.
- 90 Degrees Bend:
- Coefficient = Material Thickness 0.18, with the total bending coefficient being 0.35 2 = 0.7.
- Example Calculation: For a 90-degree bend, with each leg length being 98 mm, the total length calculation would be 98 + 98 + 0.7 = 196.7 mm.
Standardizing Tool Die Lengths
Standard bending machine tool dies typically measure 835 mm per segment. These dies can be segmented into various lengths, allowing for a combination that suits the specific dimensions of box-shaped workpieces or enclosures. This modularity is crucial for accommodating different project requirements and optimizing tool storage and handling.
Metal Bending Operations
- Operation Setup: The process involves placing the workpiece on the bending machine, lifting the brake shoe with a lever, positioning the metal, and then lowering the shoe to make the bend.
- Minimum Bending Radius: This is determined by the ductility and thickness of the metal, crucial for preventing material fatigue or breakage.
Conclusion
The art of metal bending relies heavily on the correct selection and application of bending tool dies. By understanding the distinctions between standard and special molds and accurately calculating bend dimensions, fabricators can greatly enhance the precision and quality of their metal products. Whether working with intricate components or standard parts, the right knowledge and tools are key to successful metal fabrication.
