Spline Tooth Surface Design for High-Rigidity Rotating Connections
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Solution Overview
Problem
Existing splines have limited working pressure due to inclined planes as working tooth surfaces, leading to gaps that allow dust entry and coolant leakage, reducing connection reliability and mating area.
Innovation Solution
Designing splines with a plurality of teeth forming an annular curved surface, including tooth crest and root conical surfaces and inclined planes, all of which are developable surfaces, allowing for full tooth surface fitting and continuous pretightening force distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only inclined planes are used as working tooth surfaces in existing splines, then the structure is simple, but the working pressure bearing capacity is limited and connection reliability deteriorates
Solution Approach 1:
The tooth surface is segmented into three distinct functional zones: tooth crest conical surface, inclined plane, and tooth root conical surface. Each zone independently bears working pressure, distributing the load across multiple segments rather than concentrating it on a single inclined plane surface. This segmentation allows the complex tooth surface structure to achieve high connection reliability through multi-zone pressure distribution.
Solution Approach 2:
The invention transitions from a two-dimensional inclined plane surface to a three-dimensional composite surface featuring conical surfaces at the crest and root. The conical surfaces add radial and axial dimensions to the working contact areas, enabling pressure bearing in multiple directions simultaneously. This dimensional expansion resolves the contradiction by providing both structural complexity and enhanced reliability.
2Ease of operation
If gaps are formed between mating end faces of splines, then assembly is easier, but dust enters easily and coolant leaks, reducing mating area and connection reliability
Solution Approach 1:
The tooth crest and tooth root surfaces are designed as conical surfaces with curved geometries that enable smooth mating between splines. The curved surfaces conform to each other during assembly, creating natural sealing contact that prevents dust entry and coolant leakage. The curvature allows easy assembly through self-aligning contact while simultaneously eliminating harmful gaps.
Solution Approach 2:
The continuous wavy surface formed by sequentially connected tooth surfaces acts as a flexible sealing interface between mating splines. This surface conformally contacts the mating spline, creating a seal that prevents contamination and fluid leakage while maintaining ease of assembly through its adaptable geometry.
3Ease of manufacture
If only inclined planes are used as working tooth surfaces, then machining is simpler, but the mating area is reduced and pressure bearing capacity is limited
Solution Approach 1:
The tooth surface is divided into three machinable segments: tooth crest conical surface, inclined plane, and tooth root conical surface. Each segment can be independently generated using standard machining operations. The segmentation increases the total mating area while maintaining manufacturing simplicity through modular surface generation.
Solution Approach 2:
The conical surfaces at the tooth crest and root provide curved mating areas that increase the effective contact area compared to flat inclined planes. These curved surfaces can be machined using conventional contouring operations, achieving both increased mating area and acceptable machining complexity.
4Strength
If continuous wavy surfaces with conical surfaces are used, then connection strength and reliability improve, but machining complexity increases
Solution Approach 1:
The complex continuous wavy surface is segmented into three standard geometric forms: conical surfaces and inclined planes. Each segment has well-defined machining methods, reducing the practical complexity despite the overall continuous wavy geometry. The segmentation maintains connection strength through continuous surface contact while enabling conventional machining approaches.
Solution Approach 2:
The conical surfaces provide smooth curved transitions that enhance connection strength through continuous contact. These curved surfaces can be efficiently generated using standard form tools and machining centers, balancing the geometric complexity with manufacturing capability.
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
The present disclosure provides a spline, a spline assembly, a spindle tool holder mechanism, a rotating wheel mechanism, and a transmission mechanism. A plurality of teeth evenly distributed in a circumferential direction of the spline are formed at a transmission end of the spline. A tooth surface of each of the teeth includes a tooth crest conical surface, inclined planes, and tooth root conical surfaces, and the inclined planes are inclined relative to an axis of the spline. The tooth crest conical surface, the inclined plane, and the tooth root conical surface are sequentially and tangentially connected. The tooth surfaces of the plurality of teeth are sequentially connected to form an annular curved surface, which is a first-order continuous periodic wavy surface. The tooth crest conical surface, the inclined planes, and the tooth root conical surfaces are all working tooth surfaces and are all developable surfaces. Addendums of the plurality of teeth are the same, and dedendums of the plurality of teeth are the same. When two splines are connected, gap-free full tooth surface fitting can be implemented, radial, axial, and circumferential positioning is accurate, and the connection strength and rigidity are high. The spline is suitable for high-rigidity connection between high-speed rotating members. The tooth surfaces are in smooth transition, without stress concentration and the risk of fatigue fracture.