Sheet Protrusion Forming with Split Punch for Sharp Tall Edges
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Solution Overview
Problem
Conventional methods for forming protrusions with sharp edges in sheet-like workpieces, especially those with heights equal to or greater than the sheet thickness, face challenges such as insufficient strength at gripped portions, leading to cracking and difficulty in achieving precise edges.
Innovation Solution
A protrusion forming device and method utilizing a punch unit with a large and small punch part, where the small punch part projects from the large part and is capable of insertion into a die hole, allowing for deformation of the workpiece between the die and punch units, with specific intervals and sloped faces to prevent cracking and ensure sharp edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If drawing method is used to form protrusion, then protrusion height can be formed, but edge sharpness is poor due to large R of punch and die corners
Solution Approach 1:
The punch is divided into two distinct parts: a large punch part for gripping the workpiece and a small punch part for forming the protrusion. This segmentation allows the small punch part to have a sharp edge for precise forming while the large punch part provides sufficient gripping force, resolving the contradiction between edge sharpness and corner roundness.
Solution Approach 2:
Different parts of the punch are given different geometric properties: the large punch part has a larger diameter for gripping, while the small punch part has a smaller diameter and sharp edge for precise protrusion formation. This local differentiation of properties allows simultaneous achievement of good grip and sharp edges.
2Shape
If fine blanking method is used to form sharp edges, then edge sharpness is improved, but protrusion height formation becomes difficult when height is sheet thickness or greater
Solution Approach 1:
The punch is segmented into a large punch part for gripping and a small punch part for forming. This allows the small punch part to penetrate deeply into the workpiece (enabling tall protrusions) while the large punch part maintains gripping force, overcoming the limitation of fine blanking where punch and die diameters must be approximately the same.
Solution Approach 2:
The large punch part acts as an intermediary that transmits force to the small punch part. It provides the necessary gripping force and structural support, enabling the small punch part to achieve deep penetration and tall protrusion formation without compromising stability.
3Length of moving object
If punch and die hole pinch the workpiece to form protrusion, then protrusion height can be formed, but strength at gripped portions is insufficient causing cracking
Solution Approach 1:
The large punch part is designed with a larger diameter specifically at the gripping region to distribute the gripping force over a larger area. This local increase in dimension prevents stress concentration and cracking at the gripped portions while still allowing the small punch part to form tall protrusions.
Solution Approach 2:
The large punch part first grips and secures the workpiece before the small punch part penetrates and forms the protrusion. This preliminary gripping action ensures the workpiece is firmly held, preventing cracking during the subsequent deep penetration and protrusion formation process.
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 formation of protrusions with heights at least equal to the sheet thickness while preventing cracking and achieving sharp edges, enhancing the strength and precision of formed articles, particularly suitable for applications like sheet gears where increased rotary torque is required.
Implementation Method 1
causing a workpiece to deform by pressing a part of the workpiece arrange, between the die unit and the punch unit to a side of the die unit by way of the punch unit
Data Source
AI summary
Provided are a protrusion forming device, a protrusion forming method, and a formed article, with which a height equal to or greater than the plate thickness is possible, the edges are sharp, and cracking can be prevented. This protrusion forming device is characterized by being equipped with a die unit provided with a die hole, and a punch unit having a large punch part with a size such that this part cannot be inserted into the die hole, and a small punch part that protrudes from the large punch part toward the die unit and can be inserted into the die hole, and characterized in that the workpiece is deformed by pressing a portion of the workpiece arranged between the die unit and the punch unit toward the die unit by means of the punch unit, thereby forming a protrusion.