Internal Gear Hard Finishing With Ultra-Hard Honing Tools
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Solution Overview
Problem
Current methods for machining internally geared workpieces, particularly in large series production, face challenges in achieving high-quality hard finishing due to high costs associated with processes like profile grinding, leading to poorer quality and increased noise emissions compared to externally toothed gears.
Innovation Solution
A method using a gear honing machine with a tool made of extremely hard cutting materials like polycrystalline diamond or cubic boron nitride, guided along the teeth of the workpiece for hard finishing, allowing for efficient and cost-effective machining of hardened internally toothed gear wheels with geometrically undefined cutting edges, and enabling simultaneous roughing and finishing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If profile grinding is used for hard finishing of internally toothed gears, then manufacturing precision and surface quality are improved, but production cost increases significantly
Solution Approach 1:
The patent changes the fundamental parameter of the cutting tool from conventional materials to ultra-hard materials (polycrystalline diamond or cubic boron nitride), enabling hard finishing without the need for expensive profile grinding processes. This material parameter change allows direct machining of hardened gears at lower cost while maintaining high surface quality.
Solution Approach 2:
The patent extracts the hard finishing operation from the traditional multi-step process (soft machining + hardening + profile grinding) and combines it with the roughing operation into a single machining step using ultra-hard tools, eliminating the need for separate expensive finishing processes.
2Ease of manufacture
If conventional soft machining followed by hardening is used for internally toothed gears, then manufacturing cost is reduced, but manufacturing precision and surface quality deteriorate
Solution Approach 1:
The patent performs hard finishing during the same machining operation that creates the tooth geometry, rather than as a separate subsequent operation. The ultra-hard tools machine the hardened or to-be-hardened gear teeth in one go, ensuring high precision is built in from the start rather than added later.
Solution Approach 2:
The patent merges the roughing and hard finishing operations into a single machining process using ultra-hard cutting tools, eliminating the need for separate soft machining, hardening, and profile grinding steps required by conventional methods.
3Productivity
If hard finishing processes are avoided in high-volume production, then production cost is reduced, but manufacturing precision and surface quality are compromised
Solution Approach 1:
The patent changes the tool material parameter to ultra-hard materials that can machine hardened steel directly, enabling hard finishing to be performed as part of the normal production process without requiring separate expensive finishing operations for each gear.
Solution Approach 2:
The ultra-hard cutting tools serve multiple functions: they perform both roughing and hard finishing operations on hardened gear teeth, making the machining process universal and eliminating the need for different tools or processes for different production volumes.
4Ease of manufacture
If tools with geometrically undefined cutting edges are used, then ease of manufacture is improved, but manufacturing precision may be affected
Solution Approach 1:
The patent changes the tool geometry from conventional defined cutting edges to ultra-hard materials with geometrically undefined or flexible cutting edges. The extreme hardness of polycrystalline diamond or cubic boron nitride compensates for the lack of precise geometric definition, allowing the tool to maintain precision while being easier to manufacture and dress.
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 quick and cost-effective hard finishing of internally toothed gear wheels, improving surface quality and reducing noise emissions, while being suitable for large-scale production without the need for new motion sequences in the gear honing machine.
Implementation Method 1
at least one tool, consisting at least partially of a high-hardness cutting material, is guided along the teeth of the gear... removing material from the flanks and/or, if applicable, the roots of the teeth
Data Source
Figure 1
AI summary
The invention relates to a method for machining an internally toothed workpiece, wherein the workpiece is clamped into a toothed honing machine, and wherein at least one tool that is at least partially made of a high-hardness cutting material, is guided along respective teeth of the internally toothed workpiece in order to carry out hard-fine machining of the teeth of the internally toothed workpiece.