CV Joint Outer Member Welding via Electron Beam and Press-Fit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The manufacturing of outer joint members for constant velocity universal joints faces challenges such as burrs generated during friction press-contact leading 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 increased costs.
Innovation Solution
A method involving separate cup and shaft members made of medium carbon steel, where the cup member has a cylindrical portion with a fitting hole and the shaft member has a fitting outer surface, allowing for electron beam welding with a gap and interference, enhancing press-fitting accuracy and stability, and reducing cycle time by evacuating a smaller internal space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If friction press-contact is used to join cup member and shaft member, then the joining strength is improved, but burrs are generated on the joining portion which increase hardness and distortion making subsequent turning difficult
Solution Approach 1:
The harmful burrs generated during friction press-contact are removed through turning processing before welding. This extraction of the problematic element (burrs) eliminates their negative effects on subsequent manufacturing steps while preserving the beneficial joining strength achieved through friction press-contact.
Solution Approach 2:
Turning processing is performed as a preliminary step before welding to remove burrs and create a smooth surface on the joining portion. This preliminary action prevents the burrs from interfering with the welding process and ensures high-quality welds without the complications that would arise from welding over burred surfaces.
2Productivity
If laser welding or electron beam welding is used to join cup member and shaft member, then the joining speed and precision are improved, but gas pressure variations during welding cause poor weld quality and unstable strength
Solution Approach 1:
The internal pressure of the hollow cavity portion is controlled and maintained at a substantially constant level during welding by adjusting the plunger position. This parameter change (maintaining constant pressure) prevents weld defects caused by pressure variations while enabling the use of high-speed laser or electron beam welding processes.
Solution Approach 2:
The plunger position is adjusted based on feedback from the welding process to maintain constant internal pressure. This feedback mechanism ensures that pressure variations do not occur during welding, thereby maintaining stable weld quality and strength while achieving high welding speeds.
3Reliability
If the internal space of the cup member is evacuated for welding, then the weld quality is improved by preventing oxidation, but the evacuation time increases reducing productivity
Solution Approach 1:
Instead of completely evacuating the internal space of the cup member, the patent applies a partial action by maintaining a substantially constant internal pressure (which may be atmospheric or slightly reduced pressure). This partial evacuation approach prevents oxidation during welding sufficiently to ensure weld quality while dramatically reducing the time required compared to complete vacuum evacuation.
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 improves the strength and quality of the welded portion, reduces welding costs, and enhances productivity by standardizing product types, ensuring accurate press-fitting and stable welding without burrs or defects, thus reducing production burdens.
Implementation Method 1
welding a cup member (12a) and a shaft member (13a) by radiating an electron beam (59) from an inner side of the cup member (12a) to a fitted portion between the cup member (12a) and the shaft member (13a)
Implementation Method 2
evacuating a smaller internal space
Data Source
Figure 1
Figure 2a~2c
Figure 3
AI summary
Provided is a method of manufacturing an outer joint member of a constant velocity universal joint, which is constructed by forming, through use of separate members, a cup section having track grooves formed at an inner periphery of the cup section and engageable with torque transmitting elements, and a shaft section formed at a bottom portion of the cup section, and by welding a cup member forming the cup section and a shaft member forming the shaft section, the method including: forming the cup member and the shaft member of medium carbon steel, the cup member being manufactured by preparing a cup member having a cylindrical portion and a bottom portion being integrally formed, and a fitting hole formed in a thick portion of the bottom portion in a machining step, the shaft member being manufactured by preparing a shaft member having a fitting outer surface formed at an end portion of the shaft member to be joined to the bottom portion of the cup member, which is formed in a machining step; fitting the fitting hole of the cup member to the fitting outer surface of the shaft member; and welding the cup member and the shaft member by radiating a beam from an inner side of the cup member to a fitted portion between the cup member and the shaft member, in which the fitting hole of the cup member and the fitting outer surface of the shaft member are formed of a joining portion having a gap and a press-fitting portion having an interference, and an axial dimension of the joining portion is set to be larger than an axial dimension of the press-fitting portion, the joining portion serving as a press-fitting guide.