Punching Tool With Rotary Abrasive for Sheared Edge Fatigue Strength
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Solution Overview
Problem
Existing metal sheet punching methods either require additional molds, leading to increased steps and low productivity, or result in deformed metal sheets and insufficient crack suppression in the sheared edge, limiting their applicability and fatigue strength.
Innovation Solution
A metal sheet punching device featuring a die with a circular opening and a punch with a cylindrical punching part, a rotating part with a coated abrasive, and a spring for elastic energy accumulation, allowing for one-step formation of punched holes with improved sheared edge properties without requiring additional molds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional blanking method is used to form punched hole, then productivity is high and process is simple, but fatigue strength of sheared edge is low due to tensile residual stress and rough end surface
Solution Approach 1:
The patent combines the punching operation and edge polishing operation into a single integrated process. The rotating part with coated abrasive is incorporated into the punch assembly, allowing simultaneous punching and polishing in one step, thereby improving fatigue strength without increasing process complexity
Solution Approach 2:
The polishing action is performed immediately after punching while the workpiece is still in position. The rotating abrasive surface polishes the sheared edge right after the punching operation completes, eliminating the need for separate post-processing steps and maintaining high productivity
2Strength
If large-size part is added to punch to polish sheared edge, then fatigue strength is improved, but metal sheet around punched hole becomes deformed
Solution Approach 1:
The polishing action is localized precisely to the sheared edge of the punched hole using a rotating part with coated abrasive. The polishing contact is confined to the circumferential edge region, preventing deformation of the surrounding metal sheet while effectively improving the fatigue strength of the sheared edge
3Strength
If blank holder with special shape is used to improve fatigue strength, then sheared edge properties are improved, but applicable places are limited
Solution Approach 1:
The rotating part with coated abrasive is designed to be universally applicable to various punching operations. It can be integrated into standard punch assemblies and used with different die configurations, making the fatigue strength improvement method widely applicable across different punching applications without requiring special blank holders
4Strength
If multiple molds are used for punching and polishing, then sheared edge properties are improved, but number of steps increases and productivity decreases
Solution Approach 1:
The patent merges the punching mold and polishing mold into a single integrated tool assembly. The punch with rotating abrasive performs both punching and polishing in one operation, eliminating the need for multiple separate molds and maintaining high production efficiency while improving sheared edge fatigue strength
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 device effectively reduces sheared edge unevenness, prevents crack generation, and enhances fatigue strength by polishing the sheared edge in the same direction as the punch, while also improving formability and coating properties.
Implementation Method 1
spring configured to contract and accumulate a part of a punching load as elastic energy until the punching part comes into contact and punches the metal sheet, release the elastic energy, and extend after the punching part punches the metal sheet
Implementation Method 2
coated abrasive provided on an outer circumferential surface of the rotating part and configured to polish a sheared edge of the punched hole
Data Source
AI summary
A metal sheet punching device includes: a die including a circular opening; and a punch configured to form a circular punched hole in the metal sheet supported by the die. The punch includes: a main body part; a cylindrical punching part; a rotating part disposed between the main body part and the punching part; a coated abrasive provided on an outer circumferential surface of the rotating part and configured to polish a sheared edge of the punched hole; a spring disposed between the main body part and the punching part and configured to contract and accumulate a part of a punching load as elastic energy, release the elastic energy and extend after the punching part punches the metal sheet; and a rotational motion conversion device configured to convert a linear motion in the punching direction due to extension of the spring into a rotary motion of the rotating part.