Chamfered Shaft Structure for Accurate Thread Rolling

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Solution Overview

Problem

Existing methods for forming male screw portions on shafts often result in deformation and increased manufacturing costs due to the need for recessed holes and subsequent cutting of axial end portions, which can lead to reduced accuracy and the formation of burr or protrusion excess portions.

Innovation Solution

A shaft member design with chamfered portions and supported surface portions that absorb elongation during rolling processing, allowing the male screw portion to be formed without recessed holes, thereby preventing deformation and reducing manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If recessed holes are formed in axial end surfaces to position material during rolling processing, then positioning accuracy is improved, but manufacturing complexity and post-processing requirements increase

Engineering Contradiction:
Improvepositioning accuracyVSAvoidmanufacturing complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Chamfered portions are formed in advance on the shaft member before rolling processing. These chamfered portions serve as positioning surfaces that enable accurate radial positioning during rolling without requiring subsequent cutting operations to remove recessed holes. The preliminary formation of positioning surfaces eliminates the need for post-processing while maintaining positioning accuracy.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If axial end portions are cut and removed after rolling, then positioning accuracy is improved, but male screw portion deformation may occur

Engineering Contradiction:
Improvepositioning accuracyVSAvoidmale screw portion accuracy
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The shaft member is prepared with chamfered portions before rolling processing. These pre-formed chamfered portions enable accurate positioning during rolling without requiring the material to be gripped by the male screw portion. This eliminates the risk of deformation to the male screw portion while achieving the necessary positioning accuracy.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If strong pressing force is applied during rolling processing, then male screw portion formation is improved, but burr or protrusion excess portions are formed

Engineering Contradiction:
Improvemale screw portion formationVSAvoidburr formation
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

Chamfered portions are formed in advance on the shaft member to create proper positioning surfaces. These pre-formed surfaces allow the material to be properly positioned and supported during rolling processing, enabling strong pressing force to be applied without generating burr or protrusion excess portions. The preliminary preparation of positioning surfaces prevents harmful factors that would otherwise require post-processing removal.

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 ensures high shape accuracy of the male screw portion and reduces manufacturing costs by eliminating the need for post-processing removal of excess portions, maintaining the integrity of the screw thread and minimizing deformation.

Implementation Method 1

a chamfered portion (7a, 7b) respectively formed at connection portions between an outer peripheral surface (2) and axial side surfaces (3a, 3b) on both axial sides of the shaft member (1)

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP3971429B1Shaft member and method for manufacturing male shaft
Publication Date: 2024.01.31 NSK LTD
  • EP3971429B1 patent drawingFigure 1A~1B
  • EP3971429B1 patent drawingFigure 2~3
  • EP3971429B1 patent drawingFigure 4A~4E

AI summary

A shaft member includes: an outer peripheral surface; at least one axial side surface facing an axial direction; a chamfered portion formed at a connection portion between an axial end edge of the outer peripheral surface and an outer peripheral edge of the axial side surface; and a processing target portion formed on at least a part of the outer peripheral surface. The chamfered portion includes at least one supported surface portion disposed at an axially intermediate portion of the chamfered portion and inclined radially outward as approaching the processing target portion in the axial direction. The axial end edge of the outer peripheral surface and the outer peripheral edge of the axial side surface are located radially inward than a tangent line at an axially intermediate portion of the supported surface portion, in a cross section in the axial direction.