Grooved Punch for Hydroforming Hole Formation
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Solution Overview
Problem
Conventional hydroforming processes result in significant deformation of metal surrounding holes due to punching, which is particularly problematic for thicker tubes where permanent deformation is common, making it difficult to create holes without damaging the structural integrity of the tube.
Innovation Solution
A hydroforming method and punch design that uses a cutting end with a groove to form holes in hollow blanks, allowing the surrounding material to move into and then back out of the groove, minimizing deformation by enabling the material to return to its original position, and a punch with a reduced cross-sectional area to facilitate this movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a punch is used to pierce holes in the blank after hydroforming, then holes can be formed for attachment points, but significant deformation occurs in the surrounding metal
Solution Approach 1:
The punch is modified with a groove circumferentially disposed about its cutting end, and the hydroforming process incorporates a specific pressure cycle. The material is pre-compressed during hydroforming before punch insertion, and the groove allows material to be temporarily displaced during punching, then returned to its original position. This preliminary preparation and controlled sequence of actions reduces permanent deformation around the hole.
2Ease of manufacture
If conventional punching is used on thicker tubes, then holes can be created, but permanent deformation is common and structural integrity is compromised
Solution Approach 1:
The process utilizes changes in hydroforming pressure parameters. Internal pressure is increased to compress the material before punch insertion, and then maintained at specific levels during the punching operation. This dynamic pressure control allows the material to be more resistant to permanent deformation while still allowing the punch to create the hole, thereby preserving structural integrity in thicker tubes.
3Ease of manufacture
If material is displaced during hole formation, then the hole can be created, but the surrounding material cannot return to its original position
Solution Approach 1:
The groove circumferentially disposed about the punch cutting end acts as an intermediary mechanism. During punch insertion, material surrounding the hole is displaced into the groove space. The groove serves as a temporary repository that allows material displacement necessary for hole creation, while the hydroforming pressure subsequently pushes the material back to its original position, minimizing permanent displacement.
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 approach minimizes permanent deformation around the formed holes, enabling the creation of holes in thicker tubes with minimal damage, thus preserving the structural integrity and allowing for precise feature formation without significant material displacement.
Implementation Method 1
internal hydraulic pressure exceeding the yield strength of the tube wall is applied to force the tube to expand and conform to the die cavity
Implementation Method 2
Conventional method of cold forming metal tubes to create structural members, for example, for the automotive industry, is hydroforming
Implementation Method 3
the cutting end of the punch is configured to allow material of the blank surrounding the formed hole to move away from the interior of the blank
Data Source
AI summary
A method of forming a hole in a hollow blank during a hydroforming process is provided. The method includes placing a blank in a cavity of a hydroforming die, the hydroforming die being configured to permit a punch to engage the blank. An interior of the blank is pressurized with a fluid. Further, a cutting end of a punch is applied through a wall portion of the blank and into the interior of the blank to form a hole. Furthermore, the cutting end of the punch is removed from the interior of the blank such that the cutting end of the punch is configured to allow material of the blank surrounding the formed hole to move away from the interior of the blank.