Telescopic Steering Column Inner Tube with Polygonal Cross-Section
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current telescopic steering columns require excessive material and costly machining processes due to the need for outer tubes with polygonal cross-sections and circular end sectors, which are heavy and inefficient.
Innovation Solution
An inner tube with a first end sector having a substantially circular cross-section and a second end sector with a regular polygonal section, featuring external flanges and internal recesses, is designed using a reducing and drawing method involving a conical reducing cavity and a drawing ball to reduce material usage and machining costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If outer tubes are designed with polygonal cross-section and circular end sectors to support bearings, then bearing support capability is improved, but material mass and manufacturing cost increase due to excessive wall thickness required for machining
Solution Approach 1:
The inner tube is designed with different cross-sectional geometries in different zones: a polygonal cross-section in the intermediate sector for telescopic guidance, and circular end sectors where bearings are mounted. This local differentiation allows the tube to have sufficient material thickness only where structurally necessary for bearing support, while reducing material in other areas.
Solution Approach 2:
The circular end sectors with bearing mounting capabilities are formed directly during the tube forming process through a reducing and drawing operation, rather than requiring subsequent machining. This preliminary formation eliminates the need for excessive wall thickness that would be required to accommodate machining operations.
2Reliability
If outer tubes are designed with circular end sectors for bearing assembly, then bearing support function is improved, but manufacturing complexity increases due to required machining processes
Solution Approach 1:
The circular end sectors are pre-formed during the tube manufacturing process itself through reducing and drawing operations, eliminating the need for separate machining operations. The tube is reduced in diameter and drawn into the final shape with circular end sectors already formed, integrating the bearing mounting surface creation into the primary forming process.
Solution Approach 2:
The tube undergoes parameter changes during forming, transitioning from a larger diameter polygonal tube to a reduced diameter tube with circular end sectors. The reducing and drawing process modifies the geometric parameters in-situ, creating the complex end sector geometry without requiring post-manufacturing machining operations.
3Ease of manufacture
If outer tubes have sufficient wall thickness for machining end sectors, then manufacturing of circular end sections is enabled, but weight and material usage increase
Solution Approach 1:
The circular end sectors are formed during the tube manufacturing process through reducing and drawing, rather than requiring subsequent machining. This preliminary action creates the final geometry directly, eliminating the need for excessive wall thickness that would be required to accommodate machining operations while maintaining structural integrity.
Solution Approach 2:
The tube structure is optimized with local quality variations: circular end sectors with appropriate thickness for bearing support are formed only where needed, while other portions of the tube have reduced material content. This localized optimization reduces overall weight while maintaining the necessary manufacturing capabilities where required.
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
The solution reduces material mass and manufacturing costs while maintaining effective support for bearings, ensuring proper sliding and adjustment of the steering wheel, and enhancing collision resistance.
Implementation Method 1
reducing and drawing a first end part having a polygonal cross-section of the inner tube
Data Source
AI summary
An inner tube for a telescopic steering column (8) is provided, with a first end sector (2) for assembling a bearing (9), having a substantially circular cross-section obtained by reducing and drawing, a second end sector (3) and an intermediate sector (4) having a regular polygonal section, provided with longitudinal planar external guiding faces (5), whereinthe first end sector (2) comprises a plurality of external flanges (6) emerging longitudinally from its external surface (2a) in axial alignment with at least some of the external guiding faces (5), and a plurality of longitudinal internal recesses (7) penetrating its inner surface (2b), each internal recess (7) extending under one of the external flanges (6);each external flange (6) comprises an essentially planar external surface which is at least partially flush with the external guiding face (5) with which it is aligned.