Press-Formed Thrust Race Edge Flattening Without Grinding

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Solution Overview

Problem

Conventional thrust race manufacturing methods face issues with excessive contact surface pressure at radial end portions, leading to shortened bearing life, and require grinding processes that increase manufacturing costs and yield deterioration due to roll-over generation during punching.

Innovation Solution

A press-formed product manufacturing method that reduces roll-over generation without grinding, using a punching, depressing, and trimming process with transfer working, where the pressing surface matches the axial surface to minimize roll-over formation and eliminate the need for grinding, thereby reducing processing steps and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional punching process is used to manufacture thrust race, then manufacturing simplicity is maintained, but roll-over is generated at the edges requiring additional grinding processes

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidedge flatness
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention applies a preliminary flattening process after punching to eliminate roll-over before heat treatment. This preliminary action prevents the generation of excessive contact surface pressure at radial end portions that would otherwise require post-treatment grinding, thereby maintaining manufacturing simplicity while achieving the required edge flatness.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If grinding process is added to remove roll-over, then manufacturing precision is improved, but manufacturing cost and processing time increase

Engineering Contradiction:
Improveedge flatnessVSAvoidmanufacturing efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The flattening process is performed as a preliminary step after punching and before heat treatment, eliminating the need for subsequent grinding operations. This preliminary action achieves the required edge flatness while maintaining high manufacturing efficiency by using a simple pressing operation instead of time-consuming grinding.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention extracts and eliminates the unnecessary grinding step from the manufacturing process by implementing a flattening process that prevents roll-over from affecting the final product quality. This removes the harmful element (excessive processing steps) while maintaining the beneficial element (edge flatness).

Inventive Principle:
Principle #2Taking out (Extraction)

3Manufacturing precision

If plate thickness is increased to provide cutting allowance for grinding, then manufacturing precision is ensured, but material yield deteriorates

Engineering Contradiction:
Improvedimensional accuracyVSAvoidmaterial yield
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The flattening process is applied preliminarily after punching to eliminate roll-over, which ensures that the final dimensional accuracy is achieved without requiring additional material thickness for grinding allowance. This maintains manufacturing precision while improving material yield by reducing the required plate thickness.

Inventive Principle:
Principle #10Preliminary action

4Stress or pressure

If chamfered portion is provided at radial end portions, then contact surface pressure is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improvecontact surface pressureVSAvoidstructural complexity
Core Design Contradiction:
Stress or pressureVSDevice complexity

Solution Approach 1:

The flattening process creates a substantially flat surface at the radial end portions preliminarily, which effectively reduces contact surface pressure during bearing operation. This achieves the stress reduction benefit of chamfered portions while maintaining the structural simplicity of a flat thrust race design, avoiding the need for actual chamfered geometries.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4091734B1Method for manufacturing press-molded article, method for manufacturing rolling bearing, method for manufacturing vehicle, and method for manufacturing machine
Publication Date: 2024.08.21 NSK LTD
  • EP4091734B1 patent drawingFigure 1(A)~1(B)
  • EP4091734B1 patent drawingFigure 2
  • EP4091734B1 patent drawingFigure 3

AI summary

A press-formed product manufacturing method includes obtaining a first piece (19, 55) by punching a metal material, obtaining a second piece (28, 56) by depressing an edge of a second surface (8) of the first piece (19, 55) while sandwiching the first piece (19, 55) between a first die (25) and a second die (26), and trimming a second piece (28) by using press working.