Hollow Transmission Shaft Welding for Helical Gear Alignment
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Solution Overview
Problem
Existing transmission shafts in countershaft-type manual transmissions, constructed from solid or hollow shafts, face challenges with high mass and material usage, leading to increased weight and inertia, and alignment issues with helical toothing in hollow shaft portions during press welding, resulting in suboptimal torque distribution.
Innovation Solution
A transmission shaft constructed from multiple hollow shaft portions butt press welded together, with helical toothing alignment corrected by rotating each portion by a specific angle corresponding to the pitch of the toothing to ensure precise axial alignment, using methods like spin welding or electric arc welding with magnetically moving arcs, and employing a pressure die with a rotary guide to facilitate this alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If transmission shafts are constructed as solid shafts, then strength and structural integrity are improved, but weight and mass moment of inertia increase
Solution Approach 1:
The transmission shaft is divided into multiple hollow shaft portions that are connected together. Each portion can be independently manufactured and then joined through press welding, allowing the shaft to maintain strength while reducing overall mass and moment of inertia compared to a solid shaft construction.
2Productivity
If hollow shaft portions are joined by press welding, then manufacturing efficiency is improved, but axial alignment precision of helical toothing deteriorates
Solution Approach 1:
The helical toothing is pre-formed on the hollow shaft portions before the press welding process. This preliminary action allows the toothing to be accurately manufactured on each individual portion, and the subsequent welding process is designed to maintain this pre-established alignment rather than requiring realignment after joining.
Solution Approach 2:
The invention changes the welding parameters and process characteristics to achieve both high productivity and precision. By optimizing the press welding parameters (pressure, speed, temperature control), the process maintains the axial alignment of the helical toothing while efficiently joining the hollow shaft portions.
3Manufacturing precision
If helical toothing axial alignment is corrected by rotation during joining, then toothing engagement quality is improved, but device complexity increases
Solution Approach 1:
The hollow shaft portions are designed with self-aligning features that enable automatic axial alignment of the helical toothing during the press welding process. The geometry of the shaft portions and toothing configuration allows them to self-correct alignment deviations through the welding process itself, eliminating the need for complex external alignment correction mechanisms.
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 solution ensures optimal toothing engagement and uniform torque distribution across force transmission paths, reducing material usage and weight while maintaining structural integrity and efficiency.
Implementation Method 1
The hollow shaft portions are connected to one another at abutted annular surfaces by spin welding
Implementation Method 2
plasticizing of the material at the contact surfaces facing one another
Implementation Method 3
electric arc welding with magnetically moving arcs
Data Source
AI summary
A transmission shaft of a countershaft-type manual transmission is constructed from a plurality of hollow shaft portions which are butt press welded to one another, at least two of which hollow shaft portions are provided in each instance with at least one helical toothing of a fixed wheel of a spur gear stage. The hollow shaft portions provided with a helical toothing are connected to the respective adjacent hollow shaft portion in each instance so as to be rotated by a correction angle (Δα) around their center axis in proportion to a deviation (Δx) from their axial target position, wherein the ratio between the correction angle (Δα) and the axial deviation (Δx) corresponds to the pitch (s) of the helical toothing (Δα/Δx=s).