Internal Gear Skiving for Smaller Bearing Holding Sections
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Solution Overview
Problem
The existing techniques for manufacturing gear members with internal gears face challenges in reducing the diameter of the bearing holding portion without increasing the number of processing steps, which hinders downsizing and increases manufacturing costs.
Innovation Solution
A method involving a cylindrical material with a small-diameter cylindrical portion extended to the bearing holding portion, where a skiving cutter is used to form the internal gear, terminating the skiving process at a halfway position before reaching the bearing holding portion, allowing for a smaller diameter bearing holding portion and reducing processing steps by eliminating the need for an annular groove.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If broaching or shaper processing is used to create an internal gear, then the internal gear can be formed over the entire length of the small-diameter cylindrical portion, but the bearing holding portion must have a diameter larger than the root diameter of the internal gear, which prevents reduction in diameter of the bearing holding portion
Solution Approach 1:
The patent divides the internal gear formation process into two segments: first forming the internal gear using broaching or shaper processing, then removing a portion of the internal gear to create a gap. This segmentation allows the bearing holding portion to be positioned within the gap rather than requiring the full diameter of the small-diameter cylindrical portion, thereby enabling diameter reduction while maintaining manufacturing feasibility
Solution Approach 2:
The patent extracts (removes) a portion of the internal gear to create a gap between the internal gear and the bearing holding portion. This extraction allows the bearing holding portion to have a reduced diameter since it no longer needs to accommodate the full root diameter of the internal gear, resolving the contradiction between ease of manufacture and bearing holding portion diameter
2Length of moving object
If an annular groove is provided to separate the small diameter portion from the ring gear, then the bearing holding portion diameter can be reduced, but the number of processing steps increases and manufacturing cost increases
Solution Approach 1:
The patent merges the gap creation function into the internal gear structure itself by removing a portion of the internal gear, rather than adding a separate annular groove feature. This merging eliminates the need for additional boring operations to create the annular groove, thereby reducing the number of processing steps and manufacturing cost while still achieving the diameter reduction of the bearing holding portion
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 approach enables a reduction in the diameter of the bearing holding portion, lowering costs and improving strength by reducing the number of processing steps and eliminating the need for an annular groove, while maintaining the necessary thickness and step differences for load support.
Implementation Method 1
a tooth creating step of inserting a skiving cutter from the other end portion side opposite to the one end portion of the cylindrical material to form the internal gear by skiving in the tooth width region of the small diameter cylindrical portion
Data Source
AI summary
A method of manufacturing a gear member formed into a cylindrical shape, the gear member having an internal gear disposed without overlapping the bearing holding portion in an axial direction, the method including: preparing a cylindrical material with a small-diameter cylindrical portion having an inner diameter corresponding to a tooth tip diameter of the internal gear in a tooth width region of the internal gear such that the small-diameter cylindrical portion is extended from the tooth width region toward the one end portion to reach the bearing holding portion; and inserting a skiving cutter from the other end portion side opposite to the one end portion of the cylindrical material to form the internal gear by skiving in the tooth width region of the small diameter cylindrical portion, and terminating the skiving at a halfway position before reaching the bearing holding portion and across the tooth width region.