Nibbler Assembly Arcuate Corners Elongated Hole Quality

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Solution Overview

Problem

Conventional nibbling operations in punch presses result in seam-like portions and inefficient hole formation due to lack of roll-over and fracture surfaces at corners, leading to aesthetic and efficiency issues, and existing solutions are either expensive or complex with low process efficiency.

Innovation Solution

A nibbler assembly with a die having a recessed upper surface and a punch with arcuate corners, allowing for consistent punching force and surface formation, minimizing seam-like portions and protrusions by deforming the material downward and creating fracture surfaces at corners.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a conventional punch with rectangular configuration is used to punch holes, then the punching operation is simple and fast, but seam-like portions and protrusions are formed at the corners due to lack of roll-over and fracture surfaces

Engineering Contradiction:
Improvepunching speedVSAvoidsurface quality at corners
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The punch is designed with arcuate corners instead of sharp rectangular corners. This local modification at the corner regions creates roll-over and fracture surfaces during punching, eliminating seam-like portions and protrusions while maintaining overall punching efficiency

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The corners of the punch are rounded with an arcuate shape rather than being sharp or rectangular. This curvature enables the formation of roll-over surfaces at the corners of punched holes, preventing the formation of seam-like portions and improving surface quality without significantly reducing punching speed

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Productivity

If successive holes are punched with overlap to form elongated holes, then hole formation efficiency is improved, but seam-like portions are created at the overlap ends

Engineering Contradiction:
Improvehole formation efficiencyVSAvoidappearance quality at overlap portions
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The arcuate corner design of the punch specifically addresses the overlap regions where successive holes are formed. The rounded corners ensure that the ending portions of successive holes also develop roll-over and fracture surfaces, eliminating seam-like portions at overlap ends while maintaining the efficient successive punching process

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If manual treatment with sander or file is applied to eliminate seam-like portions, then surface quality is improved, but process steps increase and efficiency decreases

Engineering Contradiction:
Improvesurface finishing qualityVSAvoidprocess efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The arcuate corner design of the punch performs the surface finishing action during the punching operation itself. The rounded corners create roll-over and fracture surfaces that automatically eliminate seam-like portions, so no subsequent manual sanding or filing is required. This preliminary action integrates finishing into the punching process, maintaining high efficiency while achieving excellent surface quality

Inventive Principle:
Principle #10Preliminary action

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 solution achieves smooth finishing of overlaps between successive holes with improved process efficiency, reduced protrusions, and lower manufacturing costs compared to existing technologies.

Implementation Method 1

the die has an upper surface formed with a recess extending from an upper peripheral portion of the through opening at an upstream side of the feed direction towards the upstream of the feed direction, and the recess is dented downwardly than other portions of the upper surface

Methodology Applied
Scientific EffectDeformation: Deformation

Implementation Method 2

the blade includes an upstream end portion in the feed direction provided with opposite corners each having an arcuate shape as viewed along the vertical direction

Methodology Applied
Scientific EffectFracture Mechanics: Fracture Mechanics

Data Source

PatentEP2540428B1Nibbler assembly for punch press and method of forming elongated hole in sheet material
Publication Date: 2017.05.10 MURATA MASCH LTD
  • EP2540428B1 patent drawingFigure 1
  • EP2540428B1 patent drawingFigure 2A~2C
  • EP2540428B1 patent drawingFigure 3A~4B

AI summary

A nibbler assembly includes a punch (1) and a die (11). The die (11) includes a through opening (12) formed therein, which opening (12) has an oblong configuration as viewed along a vertical direction. The die (11) includes an upper surface formed with a recess (13) extending from an upper peripheral portion of the through opening (12) at an upstream side of a feed direction (A) towards the upstream of the feed direction (A). The recess (13) is dented downwardly compared with other portions of the upper surface. The punch (1) includes a blade (3) substantially matching in shape with the through opening (12). The blade (3) includes an upstream end portion (3a) in the feed direction (A) provided with opposite corners (4) each having an arcuate shape as viewed along the vertical direction. The punch (1) and the die (11) are operable to punch successive holes that at least partially have a overlap along the feed direction (A) so as to form an elongated hole in a sheet material (W).