Bending machines are critical in the metalworking industry, particularly when it comes to forming large arcs. This article discusses the techniques, tools, and considerations required for bending large arcs using bending machines. It highlights the need for custom molds and the methods for achieving smooth, arc-shaped bends.
Custom Molds for Large Arc Bending
When using a bending machine to form large arcs, specialized high-low molds, also known as high-low die molds, are necessary. These molds are designed for specific radii and thus require precise drawings. Sheet metal engineers must design the sheet metal parts according to the existing molds to ensure accuracy.
How to Bend an Arc with a Bending Machine
Forming an arc with a bending machine involves small, incremental bends. Below are the detailed steps:
Required Tools:
- A bending machine
Steps:
1. Positioning: Place the central point of the desired arc beneath the bending machine, as indicated by the red circle in the diagram.
2. Incremental Bending: Gradually bend the metal in small increments to form the arc.
Observation:
- Large arcs may appear smooth without visible bends on the surface.
- Using a knife to make each bend carefully can result in a slightly marked arc upon close inspection.
Common Forming Methods in Metalworking Shops
In a typical metalworking shop, three primary methods are used for forming large arc workpieces:
Single-Process Forming Die
This method is suitable for complex shapes and offers several advantages:
- High-Quality Results: Produces smooth and even surfaces.
- No Indentations: Ensures a flawless finish without pressure marks.
Customized Large Arc Dies
These dies are used for workpieces with larger arc radii but within the bending machine's capacity. This method is cost-effective compared to single-process forming dies.
Multi-Bend Forming Method
The multi-bend method involves converting the arc into segmented lines. Utilizing existing molds and equipment, this technique allows for successful arc shaping.
Detailed Steps for Using a Bending Machine to Form an Arc
To achieve a large arc using a bending machine, follow these steps:
1. Select the Right Mold: Choose a high-low mold specific to the radius of the arc you need to form.
2. Position the Workpiece: Place the workpiece centrally on the bending machine.
3. Incremental Bending: Perform small, incremental bends to gradually shape the arc.
4. Check for Smoothness: Inspect the arc for any visible bends or marks. Adjust the pressure and bend increments if necessary.
Techniques for Bending Stainless Steel Corners into Arcs
For stainless steel countertops or similar applications, you can bend corners into arcs by following these steps:
1. Mark Lines: Draw lines spaced 2mm apart on the sheet metal.
2. Shallow Bends: Perform shallow bends along these lines using the bending machine. The initial bend angle should be kept shallow to avoid distortions.
Arc Bending on a Bending Machine Without an Arc Knife
In the absence of an arc knife, you can still achieve arc bends by using molds with smaller openings. Here's how:
1. Select Small Mouth Mold: Choose a mold with a small opening.
2. Prepare Marking Lines: Mark the lines according to the semicircle dimensions.
3. Bend Along Lines: Follow these lines to bend the sheet into an arc shape.
Custom Large Arc Bending Molds
When bending large arcs, custom molds designed for specific radii are essential. These molds are fitted on the upper and lower sections of the bending machine. However, due to their specialized nature, they are only suitable for a specific radius, making precise design essential.
Working Principle of a Bending Machine
A hydraulic bending machine operates through a combination of components:
Components:
- Frame: Provides structural support.
- Worktable: Positioned on the frame, includes a base and a pressing plate.
- Clamping Plate: Connected to the base via hinges, consisting of a seat shell, coil, and cover plate.
Operation:
1. Electromagnetic Clamping: When the coil is energized, it generates magnetic force, clamping the sheet between the pressing plate and the base.
2. Versatile Clamping: The use of electromagnetic force allows the pressing plate to be shaped into various forms, suitable for workpieces with sidewalls.
3. Mold Flexibility: Different molds can be used to meet various workpiece requirements.
Summary
Bending machines are versatile tools in metalworking, essential for forming large arcs and complex shapes. Custom molds and precise incremental bending techniques are crucial for achieving smooth, arc-shaped bends without visible marks. By understanding the methods and tools required, sheet metal engineers can produce high-quality workpieces with precision and efficiency.
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Frequently Asked Questions
What are high-low molds in bending machines?
High-low molds, also known as high-low die molds, are specialized molds designed for specific radii used in bending machines to form large arcs.
How can I bend an arc without an arc knife?
To bend an arc without an arc knife, select a mold with a small opening, prepare marking lines according to the semicircle dimensions, and bend along these lines.
What is the single-process forming die method?
The single-process forming die method is used for complex shapes, providing high-quality forming with smooth surfaces and no indentations.
How are customized large arc dies used?
Customized large arc dies are used for workpieces with larger arc radii but within the bending machine's capacity. This method is cost-effective compared to single-process forming dies.
What is the multi-bend forming method?
The multi-bend forming method converts arcs into segmented lines, utilizing existing molds and equipment to achieve precise arc shaping.
What are the main components of a hydraulic bending machine?
A hydraulic bending machine comprises a frame, worktable, and clamping plate, using electromagnetic clamping for versatile shaping.
