Rolled Thread Screw End Geometry to Minimize Burr Formation

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Solution Overview

Problem

In-feed thread rolling methods often result in burrs and sharp edges on rolled thread screws, which complicates post-processing and reduces production yield.

Innovation Solution

The solution involves a rolled thread screw design with salient excess-thickness portions, such as columnar and truncated cone parts, that are formed through thread rolling to create first and second concave surfaces and a salient part, preventing end-part wall surfaces from becoming burrs and allowing for flat axial end surfaces, thereby reducing burr formation and simplifying deburring processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If in-feed thread rolling is used to manufacture rolled thread screws, then the manufacturing process is simple and production efficiency is high, but burrs and sharp edges are generated on the rolled thread screws

Engineering Contradiction:
Improveproduction efficiencyVSAvoidsurface quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by forming salient excess-thickness portions (columnar parts and truncated cone parts) on the blank before thread rolling. These pre-formed structures serve as sacrificial material that prevents wall surface collapse during thread rolling, thereby preventing burr formation on the final product while maintaining the simplicity of in-feed thread rolling

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If in-feed thread rolling is used to manufacture rolled thread screws, then manufacturing cost is reduced, but post-processing such as deburring is required

Engineering Contradiction:
Improvemanufacturing costVSAvoidpost-processing complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent converts the potential harm of excess material into a benefit by deliberately forming salient excess-thickness portions on the blank. These portions act as a protective mechanism during thread rolling, preventing wall surface collapse and burr formation, thereby eliminating the need for deburring post-processing while maintaining low manufacturing costs

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Speed

If in-feed thread rolling is used to manufacture rolled thread screws, then manufacturing speed is high, but burr generation increases

Engineering Contradiction:
Improvemanufacturing speedVSAvoidburr generation
Core Design Contradiction:
SpeedVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-forming salient excess-thickness portions (columnar parts and truncated cone parts) on the blank before high-speed thread rolling. These pre-formed structures prevent wall surface collapse during the rapid plastic deformation process, thereby preventing burr generation even when manufacturing at high speeds

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

This approach effectively minimizes burr generation, reduces the need for deburring operations, and enhances the production yield by ensuring flat axial end surfaces and longer effective screw lengths.

Implementation Method 1

a processing step of plastically deforming the blank into a rolled thread screw

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP4029625B1Rolled thread screw and rolled thread screw manufacturing method
Publication Date: 2024.12.11 NSK LTD
  • EP4029625B1 patent drawingFigure 1
  • EP4029625B1 patent drawingFigure 2~3
  • EP4029625B1 patent drawingFigure 4~5

AI summary

A rolled thread screw includes: a screw part having, on an outer circumferential part of the screw part, thread crests and thread grooves disposed alternately along an axial direction of the rolled thread screw; and a columnar part adjoining at least one of both sides of the screw part in the axial direction. An axial end surface of the columnar part is provided with: a first concave surface concave in the axial direction; a second concave surface positioned to an outer circumference of the first concave surface and being concave in the axial direction; and a salient part positioned on a boundary between the first concave surface and the second concave surface and projecting further than a bottom of the first concave surface and a bottom of the second concave surface, the salient part extending in an arc-like shape along a circumferential direction of the columnar part as viewed in the axial direction.