Barrel-Shaped Threaded Grinding Tool for Internal Gear Accuracy
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Solution Overview
Problem
In internal gear grinding, the external diameter of the threaded grinding wheel must be smaller than the internal gear, reducing the effective surface area and leading to shorter tool life due to reduced machining accuracy.
Innovation Solution
An internal gear machining method that increases the crossed axes angle of the threaded tool, allowing for a larger slip velocity and improved cutting quality by adjusting the shaft angle based on the threaded tool's form, particularly by forming the grinding wheel with a barrel shape and varying pitch radius, enhancing machining accuracy and tool life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the external diameter of the threaded grinding wheel is set smaller than the internal diameter of the internal gear, then the grinding wheel can fit inside the internal gear for machining, but the effective surface area of the grinding wheel is reduced, resulting in shorter tool life
Solution Approach 1:
The grinding wheel is designed with a barrel shape featuring curved surfaces instead of a simple cylindrical form. This curvature allows the grinding wheel to fit inside the internal gear while maintaining a larger effective surface area through the contoured design, thereby extending tool life despite the size constraint
Solution Approach 2:
The invention introduces dimensional variation by creating a barrel-shaped grinding wheel with different diameters at different axial positions. This three-dimensional form optimization allows the grinding wheel to maximize its effective surface area within the constrained space inside the internal gear, resolving the contradiction between fitting capability and tool life
2Ease of operation
If the external diameter of the threaded grinding wheel is set smaller than the internal diameter of the internal gear, then the grinding wheel can fit inside the internal gear for machining, but the machining accuracy is reduced
Solution Approach 1:
The barrel shape with curved surfaces enables the grinding wheel to maintain better contact with the internal gear tooth surfaces despite the reduced diameter, improving machining accuracy by distributing the grinding force more effectively across the curved contact areas
3Manufacturing precision
If a barrel-shaped threaded tool with varying pitch radius is used, then the crossed axes angle can be increased to improve slip velocity and cutting quality, but the tool structure becomes more complex
Solution Approach 1:
The barrel shape with its inherent curvature provides a natural geometric framework that accommodates the varying pitch radius requirement. This curved form allows the tool to achieve the necessary crossed axes angle for improved slip velocity and cutting quality while the curvature itself simplifies the overall structural design compared to attempting to achieve the same effect with straight cylindrical forms
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 method achieves improved machining accuracy and extended tool life by increasing the slip velocity, enhancing grinding performance and allowing for easier correction of pitch errors, while preventing interference between the grinding wheel arbor and workpiece.
Implementation Method 1
a slip velocity between the external gear and the grinding wheel gear is produced using the mesh rotation and the crossed axes angle, and thereby the faces of the teeth of the external gear can be finely ground
Data Source
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Figure 3(a)~3(b)
AI summary
An internal gear processing method, using an increased slip speed to improve processing accuracy and to extent the life of a tool. An internal gear processing method configured such that a Workpiece (W) which is rotatable about a workpiece rotation axis (C1) and a barrel-shaped screw-like grindstone (11) which is rotatable about a grindstone rotation axis (B1) having a predetermined axis angle (Σ) relative to the Workpiece rotation axis (C1) are, while being meshed with each other, rotated synchronously to process an internal gear of the workpiece (W). The axis angle (Σ) is set to be large according to the amount of variation in the pitch circle radius of the screw-like grindstone (11).