Two-Step Hydroforming for Complex Metal Pipe Shapes
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Solution Overview
Problem
Current hydroforming methods struggle to produce parts with large expansion ratios and complex shapes efficiently, often requiring multiple steps, which increases costs and reduces production efficiency.
Innovation Solution
A two-step hydroforming method where a metal pipe is first expanded in one direction to achieve a circumferential length of 90% to 100% of the final product, with a height greater than the final product, and then reduced in height in the second step to shape the product, using a divided mold and internal pressure, while allowing for bending between steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple hydroforming steps are used to produce parts with large expansion ratios and complex shapes, then the manufacturing precision and shape complexity are improved, but the productivity and production efficiency deteriorate due to increased process steps
Solution Approach 1:
The hydroforming process is divided into two distinct steps: first expanding the pipe in one direction to achieve 90-100% of the final circumferential length with increased height, then reducing the height in the second step to achieve the final complex shape. This segmentation allows each step to focus on specific deformation requirements, enabling complex shapes to be achieved without requiring three or more process steps, thus maintaining high productivity.
Solution Approach 2:
In the first hydroforming step, the pipe is preliminarily expanded in one direction to achieve the target circumferential length (90-100% of final product) and increased height before the second step. This preliminary expansion prepares the workpiece for the final shaping operation, allowing the second step to focus solely on height reduction and final shape formation, thereby achieving complex shapes efficiently in just two steps.
2Ease of manufacture
If traditional bending followed by hydroforming is used, then the ease of manufacture is improved, but the expansion ratio of the bent part deteriorates and is limited
Solution Approach 1:
Instead of the conventional sequence of bending first then hydroforming, this invention inverts the sequence by performing hydroforming first to expand the pipe to the desired circumferential length and shape, then performing bending on the already-expanded workpiece. This inversion allows the pipe to achieve much larger expansion ratios (90-100% of final circumferential length) before bending, as the material has already been work-hardened and strengthened by the hydroforming process, enabling subsequent bending without excessive deformation.
3Length of moving object
If hydroforming is performed first followed by bending, then the expansion ratio is improved, but the device complexity increases due to additional process steps and equipment requirements
Solution Approach 1:
The invention merges the hydroforming and bending operations into an integrated two-step process where the hydroforming step achieves both the circumferential expansion (90-100% of final length) and the height increase, followed by a single bending operation. This merging of functions into just two process steps, rather than requiring separate equipment and multiple steps for each operation, reduces overall device and process complexity while maintaining high expansion ratios.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the production of parts with large expansion ratios and complex shapes in fewer steps, reducing costs and improving efficiency, and allows for increased application scope in automotive parts manufacturing.
Implementation Method 1
applying an internal pressure and pushing force in the pipe axial direction to said metal pipe
Implementation Method 2
loading a metal pipe into a divided mold, clamping the mold, then applying an internal pressure and pushing force in the pipe axial direction to said metal pipe
Implementation Method 3
in a second hydroforming step, reducing the height in the one direction of said intermediate product in all or part of the pipe axial direction while shaping the product to the final product shape
Data Source
AI summary
The present invention provides a hydroforming method able to increase the expansion ratio to obtain a complicated shape hydroformed product and able to reduce the number of steps of work, that is, a hydroforming method loading a metal pipe into a divided mold, clamping the mold, then applying an internal pressure and pushing force in the pipe axial direction to said metal pipe, comprising, in a first hydroforming step, expanding said metal pipe in one direction of said metal pipe cross-section to obtain an intermediate product having a circumferential length of 90% to 100% of the circumferential length of the product shape in all of the expanded part in the pipe axial direction and having a height greater than the height of the product in said one direction and at least part of the pipe axial direction, then, in a second hydroforming step, reducing the height in the one direction of said intermediate product in all or part of the pipe axial direction while shaping the product to the final product shape. Further, in the case of a shape including bending, a bending step is performed between the above first hydroforming step and second hydroforming step.