Forged Drive Shaft Sequencing to Cut Gear Tooth Machining

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Solution Overview

Problem

The processing time for machining drive shafts increases significantly with the number of teeth on the drive gear, hindering productivity in manufacturing.

Innovation Solution

A method involving forging a cylindrical recess in the gear shaft's end face, leaving parts of the tooth face and recess as forged black surfaces, and machining only specific regions to reduce processing steps and time, allowing for separate forging of spline and gear shafts with improved precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If machining is used to form the drive gear teeth, then the drive shaft can be manufactured with precise dimensions, but the processing time increases greatly according to the number of teeth

Engineering Contradiction:
Improvedimensional precision of drive gear teethVSAvoidprocessing time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The drive shaft is divided into two separate components: a spline shaft and a gear shaft. The spline shaft is forged with splines, and the gear shaft is forged with gear teeth. These two components are then assembled together, eliminating the need for time-consuming machining of teeth on a single integrated shaft while maintaining precise dimensions through controlled forging processes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The gear teeth and splines are pre-formed through forging before final assembly. By creating preliminary shaped components with near-final geometry through forging, the subsequent machining operations are minimized to only critical precision areas, significantly reducing total processing time compared to machining all features after complete shaft formation.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If all features are forged in a single operation, then productivity improves, but manufacturing precision of both spline and gear shafts deteriorates

Engineering Contradiction:
Improvenumber of forging operationsVSAvoidprecision of spline and gear shafts
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

Instead of attempting to forge both splines and gear teeth in a single complex operation, the invention segments the manufacturing process into two separate forging operations: one for the spline shaft and another for the gear shaft. This allows each component to be optimized for its specific features, achieving high precision for both while maintaining productivity through efficient sequential processing.

Inventive Principle:
Principle #1Segmentation

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 approach significantly shortens processing time and enhances productivity by reducing the number of machining steps and ensuring precise formation of spline and gear shafts, while maintaining the drive shaft's functionality.

Implementation Method 1

a shaft material 110 is prepared; a spline shaft 91 is forged on a first preliminary cylindrical part 111 of the shaft material 110; a gear shaft 92 is forged on a second preliminary cylindrical part 112

Methodology Applied
Scientific EffectPlasticity: Plasticity

Data Source

PatentEP3424612B1Method for manufacturing forged drive shaft and forged drive shaft
Publication Date: 2021.01.20 MUSASHI SEIMITSU INDUSTRY CO LTD
  • EP3424612B1 patent drawingFigure 1
  • EP3424612B1 patent drawingFigure 2
  • EP3424612B1 patent drawingFigure 3

AI summary

A method for manufacturing a forged drive shaft includes a step of preparing a shaft material (110) having a first preliminary cylindrical part (111) that has a first diameter and extends in an axial direction thereof, a second preliminary cylindrical part (112) that has a second diameter that is larger than the first diameter, and a preliminary intermediate shaft part (113) that connects to each other the first preliminary cylindrical part and the second preliminary cylindrical part and that has a diameter larger than the first diameter but smaller than the second diameter; a step of forging a spline molded product (128) by inserting the shaft material into a profile space of a first die (114) to mold the spline molded product (128) having a spline shaft (91) having a first diameter on a first end side of the shaft material within the first die; and a step of forging a gear molded product (138) by inserting the spline molded product via the spline shaft part side into a second die (131) to mold the gear molded product (138) having a gear shaft (92) on an outer periphery on a side opposite to the spline shaft within the second die. This provides a method for manufacturing the forged drive shaft that can contribute to a shortening of the processing time and an improvement in productivity by eliminating machining as much as possible while maintaining the function as a drive shaft.