Double-Die Deep Drawn Cup Forming for Uniform Wall Thickness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional deep drawing methods struggle with forming uniform thickness and avoiding defects in pressure vessels, particularly with high strength, low alloy metals, and require secondary machining that can introduce defects or microcracking.
Innovation Solution
A double die configuration using a top die with a tractrix profile and a bottom die with specific draw lines, allowing simultaneous shaping and thinning of metal blanks into deep drawn cups, followed by a smash operation to prepare the cup for welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional drawing methods are used to form deep drawn cups, then the cup shape is formed, but the material thickness becomes non-uniform and microcracks are introduced
Solution Approach 1:
The single drawing operation is segmented into two sequential drawing operations through a double die configuration. The first die performs initial drawing with a tractrix profile, and the second die performs final drawing with a different profile, allowing each stage to optimize for uniform thickness without over-stressing the material
Solution Approach 2:
The die profiles are dynamically optimized with specific curvature radii and draw line configurations that adapt to the material flow during drawing. The tractrix profile in the first die and the optimized profile in the second die create dynamic stress distribution that prevents microcrack formation while ensuring uniform thickness
2Strength
If conventional drawing methods are used with high strength, low alloy metals, then the desired cup shape is achieved, but microcracking and defects are introduced into the material
Solution Approach 1:
The drawing parameters are changed by using a double die configuration with specific curvature radii (R1, R2, R3, R4) and draw line positions that optimize the stress state during forming. This allows high strength, low alloy metals to be formed without exceeding their ductility limits and creating microcracks
Solution Approach 2:
The forming process is segmented into two stages, each with optimized parameters for the specific metal grade. The first die uses a tractrix profile suitable for initial forming, while the second die uses a different profile for final shaping, preventing excessive localized stress that would cause microcracking in high strength metals
3Manufacturing precision
If secondary machining is performed to prepare cup tops for welding, then a flat smooth welding surface is achieved, but defects and microcracking are introduced
Solution Approach 1:
The die profiles are designed with preliminary action that pre-forms the cup top surface to be substantially flat and smooth during the drawing operation itself. This eliminates the need for subsequent machining operations that would compromise material integrity
Solution Approach 2:
The shaping function and surface preparation function are merged into a single drawing operation through the double die configuration. The second die not only completes the cup shaping but also simultaneously prepares the welding surface, eliminating the separate machining step that introduces defects
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
The method achieves uniform cup thickness and reduces defects, enabling the use of high strength, low alloy metals without secondary machining, and prepares cups for strong welds.
Implementation Method 1
a tractrix profile region and a first draw line downstream of the tractrix profile region... wherein the tractrix profile region has a tractrix curvature configured based on the outer diameter of the metal blank
Implementation Method 2
a first ironing of a sidewall thickness occurs as the metal blank is drawn through the first draw line and a second ironing of a sidewall thickness occurs as the intermediate cup is drawn through the second draw line
Implementation Method 3
a punch for applying a pressure to the metal blank to draw the metal blank into the top and bottom dies
Data Source
AI summary
An apparatus for forming a deep drawn cup can include a double die that is adapted to form a cup shape and iron a wall thickness of the drawn cup in a single operation.