Open-Die Hydroforming Press with Integrated Deep Drawing
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Solution Overview
Problem
Conventional manufacturing processes for metal tanks and containers with thick bottoms or non-circular cross-sections face challenges in achieving high deformation capacity, uniform stress distribution, and quality finishes due to high hydraulic loads and stress irregularities, leading to low-quality products with visible marks and improper ferrule assembly.
Innovation Solution
The integration of a high-capacity open-die hydroforming process with a deep-drawing capability, utilizing a modular press design with adjustable hydraulic cylinders and a specific tooling system for precise deformation control, allowing for large deformation heights and uniform force distribution, along with a lubricant emulsion for preventing material cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional hydroforming process is used for thick sheet metal, then high hydraulic load is required, but stress distribution becomes irregular and material cracking occurs
Solution Approach 1:
The patent applies preliminary deep-drawing action before hydroforming to pre-shape the sheet metal and create favorable stress distribution patterns. This preliminary deformation prepares the material for subsequent hydroforming, enabling uniform stress distribution throughout the thick sheet metal (8mm) during the main forming operation, thereby preventing stress concentration and material cracking.
2Length of moving object
If high hydraulic load is applied to achieve large deformation height, then deformation capacity increases, but equipment complexity and hydraulic system requirements increase
Solution Approach 1:
The deep-drawing process is performed as a preliminary action before hydroforming to achieve part of the deformation height requirement. This preliminary shaping reduces the subsequent hydroforming stroke needed, allowing large total deformation heights (500mm) to be achieved without requiring excessively high hydraulic loads, thereby simplifying the hydraulic system design.
Solution Approach 2:
The patent combines deep-drawing and hydroforming into a continuous multi-stage process without intermediate handling. The deep-drawing stage transitions seamlessly into the hydroforming stage, maintaining continuous useful action on the workpiece. This continuity enables progressive deformation accumulation to achieve large deformation heights while distributing the hydraulic load requirements across multiple controlled stages rather than requiring a single high-load operation.
3Manufacturing precision
If conventional single-stage forming is used, then process simplicity is maintained, but uniform deformation and high-quality finish cannot be achieved
Solution Approach 1:
The patent segments the forming process into two distinct stages: deep-drawing stage and hydroforming stage. Each stage performs a specific function - deep-drawing creates preliminary shape and favorable stress distribution, while hydroforming achieves final uniform deformation and high-quality finish. This segmentation of the forming process enables both deformation uniformity and manufacturing precision that cannot be achieved in a single stage.
Solution Approach 2:
The deep-drawing process serves as a preliminary action that prepares the sheet metal for the final hydroforming operation. This preliminary shaping creates optimal initial conditions including favorable stress distribution and pre-formed geometry, which enables the subsequent hydroforming stage to achieve uniform deformation and high-quality surface finish throughout the thick sheet metal.
4Adaptability or versatility
If tabs are formed after hydroforming, then assembly features are added, but stress concentration and material defects occur
Solution Approach 1:
The patent forms tabs during the deep-drawing stage as a preliminary action before the main hydroforming operation. By creating tabs in the preliminary deep-drawn state, the subsequent hydroforming process deforms the entire part including the tab areas uniformly under hydrostatic pressure. This prevents stress concentration at tab locations and avoids material defects that would occur if tabs were formed after hydroforming when the material is already in its final stressed state.
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
Enables the production of high-quality bottoms with uniform deformation and stress distribution, achieving deformations up to 8 mm thickness and 500 mm height with materials like AISI 316L stainless steel, and allows for the integration of tabs without stress concentration, improving the assembly fit and reducing material defects.
Implementation Method 1
The hydroforming process for the described application is based on an open die that defines, in a plan view, the outer perimeter of the final part. Thus obtaining a permanent bulging of the workpiece... The possibility of incorporating a deep-drawing process prior to the hydroforming process... Its high hydraulic capacity, which enables the deformation of large thicknesses at great deformation heights
Implementation Method 2
along with a lubricant emulsion for preventing material cracking
Data Source
Figure 1a~1
Figure 2a~2
Figure 3
AI summary
A hydroforming press with open die and integrated deep-drawing, based on the principle of applying hydrostatic pressure for creating a permanent deformation on a sheet metal, which employs an open die that defines, in a plan view, the outer perimeter of the final part, and allows for a permanent bulging to be formed in the same, while making it possible to incorporate a deep-drawing process prior to the hydroforming process in order to integrate the tab parallel to the hydroforming direction. The open die is located on a horizontal plane inside the press and a plurality of hydraulic cylinders (6) operate on it, of which at least two of them also operate as actuator cylinders, in charge of lowering the die onto the part (1) to be shaped, while all of them come into operation, moving and pressing the female portion (3) of the die against the sheet metal (1) placed on the male portion (2) of the die, before applying the hydroforming hydraulic pressure, operating in the opposite direction, thereon.