How to make pipe bending dies for a hydraulic press?

Table of Contents

1. Introduction
2. Materials and Tools Required
3. Step-by-Step Guide to Making Pipe Bending Dies
4. Hongli Pipe Machinery Solutions
5. Numerical Analysis
6. References

Introduction

Pipe bending is a vital process in many industrial applications, and hydraulic press machines often require customized bending dies for effective operation. This article provides detailed instructions on making pipe bending dies for a hydraulic press, ensuring precision and efficiency.

Materials and Tools Required

• High-strength steel plate (A36 or equivalent)
• CNC milling machine
• Lathe machine
• Angle grinder
• Measuring tools (calipers, micrometer)
• Welding equipment
• Heat treatment furnace

Step-by-Step Guide to Making Pipe Bending Dies

1. Design the Die

Begin by designing the die using CAD software. The die's radius should match the pipe's internal radius plus the wall thickness. Ensure that the bend angle matches the required pipe angle. For a 90-degree bend, the die’s arc length must correspond to the pipe's outer diameter.

2. Cut the Metal

Use a CNC milling machine to cut the steel plate into the die’s rough shape. Ensure the cutting dimensions account for finishing tolerances. A rough dimension tolerance of ±0.5mm is recommended for initial cuts.

3. Shape the Die

Use a lathe to finish the die's surface, ensuring a smooth finish. This is crucial for reducing friction during bending. The surface roughness should be less than 3.2 μm.

4. Heat Treatment

Heat treat the die to increase hardness. Typical treatment involves heating to 800°C and quenching, followed by tempering at 600°C to improve toughness.

5. Fine-tune the Dimensions

Finish the die to the precise dimensions using an angle grinder. Final dimensions should be within ±0.1mm tolerance of the design specifications.

6. Assembly and Testing

Assemble the die onto the hydraulic press and conduct a test bend using a sample pipe. Measure the bend for accuracy, ensuring the radius and angle are within specified tolerances.

Hongli Pipe Machinery Solutions

Hongli Pipe Machinery offers a range of ready-made pipe bending solutions, including hydraulic pipe benders equipped with specialized dies. Their machines cater to different pipe diameters from 10mm to 200mm, supporting both thin-wall and thick-wall pipes. Hongli's dies are heat-treated for longevity and precision-engineered for minimal deformation.

Numerical Analysis

A critical aspect of die making is understanding the forces involved in bending. The formula for calculating the bending load (P) required is:

P = (k * σ * π * D² * t) / (8 * R)

Where:

• k = material constant (1.33 for most steels)
• σ = yield strength of the pipe material (in Pa)
• D = outer diameter of the pipe (in meters)
• t = wall thickness of the pipe (in meters)
• R = bend radius (in meters)

References

• Hongli Pipe Machinery Co., Ltd. www.hongli-machine.com
• Machinery's Handbook, 30th Edition, Industrial Press
• Modern Die Making Techniques by Robert B. Smith