Punch Profile Uniform Sharpness Reduces Deflection
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Solution Overview
Problem
Conventional punches for punching metal require high forces due to dull cutting edges, misalignment leading to chipping, and labor-intensive methods for cutting holes in thick stainless steel, with existing tools wearing out quickly and requiring custom machining.
Innovation Solution
A punch assembly with a novel punch profile providing uniform sharpness, increased punch-to-die clearance, and an improved sleeve for reduced deflection and alignment issues, allowing for lower punching forces and extended tool life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional punches with neutral or negative cut edge geometry are used, then punching force is reduced, but cutting edge durability decreases and chipping frequency increases
Solution Approach 1:
The patent applies different geometries to different parts of the cutting edge. The majority of the cutting edge has a negative angle for durability, while specific localized portions have a positive angle to initiate clean cuts. This local differentiation resolves the contradiction between overall durability and localized cutting effectiveness.
Solution Approach 2:
The cutting edge is segmented into multiple zones with different geometries. The cutting edge includes a first portion with a first angle and a second portion with a second angle, allowing each segment to perform its specific function (durability vs. cut initiation) without compromising the other.
2Productivity
If larger punch diameter is used to punch bigger holes, then productivity increases, but axial deflection and tipping increase requiring higher punching forces
Solution Approach 1:
The pilot hole is drilled beforehand to provide initial alignment and support for the large diameter punch. This preliminary action prevents axial deflection and tipping during the punching operation, allowing large holes to be punched with reduced forces.
Solution Approach 2:
The pilot hole acts as an intermediary element between the workpiece and the large diameter punch. It provides guidance and support, enabling the punch to maintain alignment and reduce deflection without requiring excessive punching force.
3Ease of manufacture
If standard cutting tools are used to machine punch profiles, then manufacturing complexity is reduced, but the resulting punches have non-uniform sharpness along the perimeter
Solution Approach 1:
The patent changes the geometric parameters of the cutting edge by incorporating angled surfaces (positive and negative angles) that can be machined with standard tools. These parameter changes allow conventional manufacturing methods to produce uniform cutting edges with consistent sharpness along the entire perimeter.
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 punch assembly reduces punching forces, increases tool durability, and minimizes chipping by maintaining consistent geometry and alignment, enabling efficient punching of large holes in thick stainless steel with standard tools.
Implementation Method 1
When the hand pump of the hydraulic punch driver is actuated, hydraulic fluid forces the ram to pull the draw stud
Data Source
AI summary
A punch assembly includes a punch, a sleeve, a draw stud and a die. The punch has a punch profile which provides a cutting edge that has a uniform “sharpness” along entire perimeter of the punch. The punch assembly provides additional punch-to-die clearance over what was done in the prior art. This reduces excessive punching forces which result from axial deflection of the draw stud and “tipping” of a large diameter punch as the draw stud deflects under a load.