Inner Shaft Male Spline Phase Alignment for Coating Uniformity
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Solution Overview
Problem
Existing extendable and contractible shafts for steering apparatuses face challenges in aligning the phases of the male spline section and cutting tool during the finishing process for forming a synthetic resin coating, leading to potential uneven coating thickness and increased weight due to unnecessary tapered sections or non-engaging spline portions.
Innovation Solution
An inner shaft with a connecting rod section having a larger outer diameter at the tip-end and a male spline section coated with synthetic resin, featuring positioning means such as concave grooves on the outer-circumferential surface to align the cutting tool during the finishing process, preventing unnecessary weight increase by avoiding non-engaging spline sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the male spline section is extended beyond the engagement portion with the female spline section to enable phase alignment during finishing process, then the coating uniformity is improved, but the weight of the inner shaft increases
Solution Approach 1:
The invention divides the spline section into two functional parts: an engagement portion that interfaces with the female spline section, and a non-engagement portion that extends beyond the female spline section to enable phase alignment during the finishing process. This segmentation allows each part to serve its specific function without compromising the other.
Solution Approach 2:
The male spline section is preliminarily extended beyond the engagement portion during manufacturing to establish the correct phase relationship with the cutting tool before the finishing process. This preliminary extension ensures that the phase alignment can be accurately achieved during coating formation, and the non-engagement portion can be trimmed later to remove the temporary extension.
2Manufacturing precision
If the male spline section is extended beyond the engagement portion to align phases during finishing, then the coating thickness uniformity is improved, but the device complexity increases
Solution Approach 1:
The spline section is segmented into an engagement portion for functional connection and a non-engagement portion for process assistance. This clear division simplifies the overall design by assigning specific roles to each segment, making the extended structure easier to understand and manufacture despite the added complexity.
Data Source
Figure 1(A)~1(C)
Figure 2(A)~2(B)
Figure 3(A)~3(C)
AI summary
Provided is construction and a manufacturing method of an inner shaft for an extendable and contractible shaft for which finishing for forming a synthetic resin coating layer 19a on the outer-circumferential surface of a male spline section 14b can be performed easily, while at the same time an increase in weight thereof is suppressed. A concave groove 22 that extends in the axial direction is provided on the outer-circumferential surface of the male spline section in a state so as to be continuous in the axial direction with one male spline groove 23 of the male spline grooves 23 of the male spline section 14b. A portion of the concave groove 22 that is separated in the axial direction from the male spline section 14b is used to perform phase alignment of a cutting tool for performing a finishing process of a coating layer 19a and unevenness in the circumferential direction of the male spline section 14b.