Spline Shaft Coupling Positioning via Screw Pressing
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Solution Overview
Problem
Conventional ball spline mechanisms in robots face challenges in accurately positioning and fixing mounting members without requiring complex machining or high pressing forces, especially in horizontal articulated type robots.
Innovation Solution
A coupling system with a body member, spline shaft, positioning mechanism, and fixing portion, where a screw member with a circular or spherical pressing part is used to position and fix the body member in the circumferential direction of the spline shaft, utilizing the spline grooves for accurate positioning without specialized machining, and allowing easy detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mounting members are fixed to the shaft using complex machining or high pressing forces, then reliable fixation is achieved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The mounting member is divided into a body member and a separate positioning mechanism. The positioning mechanism includes a pressing member that can be independently adjusted to press against the spline groove, while the body member contains the fitting hole for the spline shaft. This segmentation allows simple fixation without complex integrated mechanisms.
Solution Approach 2:
The pressing member acts as an intermediary element between the screw member and the spline groove. It translates the rotational motion of the screw member into radial pressing force against the spline groove, enabling positioning without direct complex mechanical engagement.
2Manufacturing precision
If specialized machining is used to position the body member on the spline shaft, then positioning precision is improved, but manufacturing difficulty increases
Solution Approach 1:
The spline groove on the spline shaft serves a dual function: it transmits power/motion and simultaneously provides the positioning surface for the pressing member. The pressing member automatically positions itself by pressing against the spline groove without requiring any specialized positioning features or machining on the spline shaft.
Solution Approach 2:
The spline groove is designed to perform multiple functions: power transmission and circumferential positioning. This eliminates the need for separate positioning features like keys, splines, or specialized machined surfaces, simplifying manufacturing while maintaining precision.
3Strength
If high pressing forces are applied to fix the body member, then fixation strength is improved, but the risk of damaging the spline groove increases
Solution Approach 1:
The pressing member is designed with adjustable pressing force through the screw mechanism. The operator can gradually increase the pressing force to the minimum level required for secure positioning, avoiding excessive force that could damage the spline groove. The dynamic adjustment capability allows optimization between fixation strength and groove protection.
4Ease of operation
If the positioning mechanism uses a simple screw member, then ease of operation is improved, but positioning precision may be insufficient
Solution Approach 1:
The pressing member has a spherical pressing surface that contacts the spline groove. This spherical geometry allows automatic self-alignment and precise positioning when the screw member is rotated, as the sphere naturally finds the correct contact point on the curved spline groove surface, enhancing positioning precision while maintaining simple operation.
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
Enables accurate and secure positioning of the body member on the spline shaft without complex machining, allowing for reliable engagement and easy detachment, while maintaining the positioning state without high pressing forces, thus enhancing the mounting efficiency of robot components.
Implementation Method 1
the positioning mechanism includes a screw hole provided in the body member so as to penetrate from an outer surface of the body member to an inner surface of the fitting hole along a radial direction, a screw member fastened into the screw hole
Implementation Method 2
a pressing part having a circular cross section, provided in a tip of the screw member, and pressed against the spline groove by fastening of the screw member into the screw hole
Data Source
AI summary
A coupling including a body member including a fitting hole into which an end of a spline shaft is fitted, and a connecting portion, the shaft including spline grooves linearly extending in an axial direction in a circumferential direction; a positioning mechanism positioning the body member in the circumferential direction with respect to the shaft fitted into the fitting hole; and a fixing portion fixing, to the shaft, the body member being positioned. The positioning mechanism includes a screw hole provided in the body member so as to penetrate from an outer surface of the body member to an inner surface of the fitting hole, a screw member fastened into the screw hole, and a pressing part having a circular cross section, provided in a tip of the screw member, and pressed against the spline groove by fastening of the screw member into the screw hole.