CV Joint Face Spline Forging for Precision and Durability

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Solution Overview

Problem

Existing methods for forming face splines in constant velocity joints lack efficiency and quality, hindering low-cost mass production while ensuring mechanical integrity.

Innovation Solution

A two-stage process involving hot forging to create a preliminary face spline followed by cold forging, with optimized die configurations and lubrication, to form high-quality face splines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional single-stage cold forging is used to form face splines, then manufacturing cost is reduced, but manufacturing precision and mechanical quality deteriorate

Engineering Contradiction:
Improveface spline qualityVSAvoidmanufacturing complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The face spline forming process is segmented into two distinct stages: hot forging to create the preliminary shape, and cold forging to refine the final geometry. This segmentation allows each stage to be optimized independently - hot forging handles the rough shaping when material is more formable, while cold forging achieves the precise final dimensions and surface quality, thereby resolving the contradiction between manufacturing precision and ease of manufacture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The hot forging process performs preliminary action by creating the basic face spline shape before the cold forging stage. This preliminary formation of the tooth profile and overall geometry prepares the workpiece for the subsequent precision cold forging operation, enabling the final stage to focus solely on achieving high manufacturing precision without the complexity of forming the entire shape from scratch.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If hot forging is used to form preliminary face spline, then material formability is improved, but additional processing steps are required

Engineering Contradiction:
Improvematerial formabilityVSAvoidmanufacturing efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The invention utilizes parameter changes by transitioning the material from a hot state during forging to a cold state for finishing. Heating the material during hot forging dramatically improves formability and reduces resistance to deformation, allowing complex face spline geometries to be formed more easily. The subsequent cooling and cold forging stage then achieves precise final dimensions, balancing the trade-off between improved formability and manufacturing efficiency.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If face splines are formed on constant velocity joint, then dynamic connection with wheel hub is enabled, but manufacturing complexity increases

Engineering Contradiction:
Improveconnection capabilityVSAvoidmanufacturing process complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention merges the face spline formation process with the constant velocity joint manufacturing by integrating the tooth profile formation into the existing hot and cold forging operations. Rather than adding a separate machining process for the face splines, the tooth profiles are formed directly during the forging stages, combining multiple functions (joint shaping and spline formation) into unified manufacturing processes, thereby enabling dynamic connection capability without proportionally increasing manufacturing complexity.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables low-cost mass production of face splines with enhanced mechanical quality and durability.

Implementation Method 1

forming an intermediate formed product by forming a preliminary face spline on a base material through hot forging

Methodology Applied
Scientific EffectHot forging: Plasticity

Implementation Method 2

during the cold forging, pressure is applied to the inclined side surfaces of the preliminary face spline so that material flows toward the bottom, thereby forming the face spline

Methodology Applied
Scientific EffectCold forging: Plasticity

Data Source

PatentEP4644018A1Method for forming face spline on constant velocity joint
Publication Date: 2025.11.05 HANSAE MOBILITY CO LTD
  • EP4644018A1 patent drawingFigure 1
  • EP4644018A1 patent drawingFigure 2
  • EP4644018A1 patent drawingFigure 3

AI summary

The method for forming a face spline in a constant velocity joint includes forming a preliminary face spline on a base material through hot forging to produce an intermediate formed product, and additionally forming the preliminary face spline into the face spline through cold forging. The preliminary face spline has a tooth profile including inclined side surfaces and a bottom located between the inclined side surfaces, and during the cold forging process, pressure is applied to the inclined side surfaces so that the material flows toward the bottom.