Outer Joint Member Welding via Vacuum Laser Beam

Solution Overview

Problem

The manufacturing of outer joint members for constant velocity universal joints faces challenges such as burrs generated during friction welding, which lead to high hardness and distorted shapes, making turning difficult, and poor welding quality due to gas pressure variations during laser or electron beam welding, resulting in unstable strength and inspection issues.

Innovation Solution

A method involving laser or electron beam welding of cup and shaft members in a sealed vacuum space to prevent burr formation and air bubbles, with optimized heat treatment and chamfer designs to enhance welding efficiency and inspection accuracy, using medium carbon steel and forming welding depth checking chamfers to ensure proper welding depth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If friction welding is used to join cup member and shaft member, then the joining strength is improved, but burrs are generated on the joining portion which have high hardness and distorted shape making subsequent turning difficult

Engineering Contradiction:

Improvejoining strengthVSAvoidease of burr removal

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical friction welding process with laser welding or electron beam welding. This substitution eliminates the generation of burrs with high hardness and distorted shapes that occur in friction welding, while still achieving strong joining between the cup member and shaft member. The laser or electron beam welding creates a cleaner weld zone without the mechanical deformation and burr formation characteristic of friction welding.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent performs laser welding or electron beam welding in a vacuum environment. This inert environment prevents oxidation and contamination during welding, and also prevents gas pressure variations that would cause molten material blowing and air bubble formation. The vacuum environment ensures high welding quality without the harmful effects of atmospheric gas pressure changes.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Ease of manufacture

If laser welding or electron beam welding is used to join cup member and shaft member, then burr formation is prevented, but gas pressure variations cause molten material blowing and air bubble formation resulting in poor welding quality

Engineering Contradiction:

Improveease of burr removalVSAvoidwelding quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent performs laser welding or electron beam welding in a vacuum environment. This inert environment prevents oxidation and contamination during welding, and also prevents gas pressure variations that would cause molten material blowing and air bubble formation. The vacuum environment ensures high welding quality without the harmful effects of atmospheric gas pressure changes.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

3Strength

If friction welding is used to join cup member and shaft member, then the joining strength is improved, but the cycle time is increased due to multiple turning passes required to remove hard burrs

Engineering Contradiction:

Improvejoining strengthVSAvoidmanufacturing cycle time

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The patent replaces the mechanical friction welding process with laser welding or electron beam welding. This substitution eliminates the generation of burrs with high hardness and distorted shapes that occur in friction welding, while still achieving strong joining between the cup member and shaft member. The laser or electron beam welding creates a cleaner weld zone without the mechanical deformation and burr formation characteristic of friction welding.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent skips the time-consuming multiple turning passes that are required to remove hard burrs from friction welding. By using laser or electron beam welding in vacuum, the process directly produces high-quality welds without burrs, allowing the manufacturing process to rush through to the next operation without the productivity-reducing intermediate turning steps.

Inventive Principle:

Principle #21Skipping (Rushing through)

4Strength

If friction welding is used to join cup member and shaft member, then the joining strength is improved, but the number of inspection steps is increased due to difficulty in ultrasonic flaw detection

Engineering Contradiction:

Improvejoining strengthVSAvoidinspection process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical friction welding process with laser welding or electron beam welding. This substitution eliminates the generation of burrs with high hardness and distorted shapes that occur in friction welding, while still achieving strong joining between the cup member and shaft member. The laser or electron beam welding creates a cleaner weld zone without the mechanical deformation and burr formation characteristic of friction welding.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method increases the strength and quality of the welded portion, reduces manufacturing costs, and enhances inspection accuracy and productivity by preventing burrs and air bubbles, while standardizing product types and reducing production burdens.

Implementation Method 1

welding the cup member and the shaft member by radiating a beam from an outer side of the cup member to an abutment portion between the cup member and the shaft member in a radial direction of the cup member

Methodology Applied

Scientific EffectLaser beam welding: Laser Beam Welding

Implementation Method 2

welding the cup member and the shaft member by radiating a beam from an outer side of the cup member to an abutment portion between the cup member and the shaft member in a radial direction of the cup member

Methodology Applied

Scientific EffectElectron beam welding: Welding

Implementation Method 3

welding the cup member and the shaft member by radiating a beam from an outer side of the cup member to an abutment portion between the cup member and the shaft member in a radial direction of the cup member

Methodology Applied

Scientific EffectVacuum: Vacuum

Data Source

PatentUS10788078B2Outer joint member of constant velocity universal joint

Publication Date: 2020.09.29 NTN CORP

AI summary

Provided is a method of manufacturing an outer joint member of a constant velocity universal joint, which is constructed by forming a cup section having track grooves, and a shaft section, and by welding a cup member and a shaft member, the method including: forming the cup member and the shaft member of medium carbon steel; preparing a cup member having a cylindrical portion and a bottom portion integrally formed by forging, and a joining end surface in a machining step; preparing a shaft member having a joining end surface formed in a machining step; bringing the joining end surface of the cup member and the joining end surface of the shaft member into abutment against each other; welding the cup member and the shaft member by radiating a beam; and performing, after the welding, an ultrasonic flaw detection-inspection step.