PCBN Superhard Tool Tip with Gradient Intermediate Layers
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Solution Overview
Problem
There is a need for an alternative superhard tip for rotary machine tools that addresses the limitations of existing superhard materials in terms of wear resistance, de-lamination, and robustness when machining hard-to-machine materials like titanium and CFRP, where current solutions often suffer from high shear stress and wear rates.
Innovation Solution
A superhard tip for rotary machine tools is developed, featuring a PCBN structure joined to a cemented carbide substrate via multiple intermediate layers comprising superhard material grains and metal carbide grains dispersed in a metal binder, which enhances the transition of properties and reduces the risk of de-lamination and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a PCBN structure is directly joined to a cemented carbide substrate, then manufacturing simplicity is maintained, but de-lamination and wear resistance deteriorate under high shear stress
Solution Approach 1:
The patent employs a composite structure with multiple intermediate layers between the PCBN superhard structure and the cemented carbide substrate. These intermediate layers contain varying proportions of superhard material grains, metal carbide grains, and metal binder material, creating a gradient composite that transitions properties from the superhard structure to the substrate, thereby improving wear resistance and preventing de-lamination while maintaining manufacturing feasibility
Solution Approach 2:
The intermediate layers are designed with locally varying compositions - each layer has a specific mixture of superhard material grains, metal carbide grains, and metal binder material. This local quality variation allows each layer to be optimized for its specific position in the gradient, with layers closer to the PCBN structure having higher superhard material content and layers closer to the substrate having more metal carbide and binder content
2Reliability
If superhard material is used in rotary machine tools, then wear resistance is improved, but de-lamination occurs under high shear stress
Solution Approach 1:
The gradient composite structure with multiple intermediate layers creates a gradual transition in material properties from the PCBN superhard structure to the cemented carbide substrate. This gradual transition prevents abrupt property changes that cause de-lamination under shear stress, while still maintaining the wear resistance benefits of the superhard material
Solution Approach 2:
The intermediate layers utilize parameter changes in material composition - specifically, varying the proportions of superhard material grains, metal carbide grains, and metal binder material across different layers. This parameter gradient allows the structure to accommodate shear stress by progressively transitioning from the hard but brittle PCBN to the more ductile cemented carbide substrate
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 solution provides improved wear resistance, reduced risk of de-lamination, and enhanced robustness, allowing for efficient machining of hard materials like titanium and CFRP with reduced burrs and defects, while maintaining simplicity and cost-effectiveness in manufacturing.
Implementation Method 1
the intermediate layers comprising grains of superhard material, such as synthetic or natural diamond, or cubic boron nitride (cBN), and grains of a metal carbide material dispersed in a metal binder material
Implementation Method 2
PCBN material comprises cubic boron nitride (cBN) particles within a matrix comprising metal and / or ceramic material
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A tip (20) for a rotary machine tool comprising a superhard structure (12) joined to a cemented carbide substrate14by means of at least one intermediate layer (161, 62, 163) disposed between the superhard structure (12) and the cemented carbide substrate (14), the intermediate layer or layers (161, 162, 163) comprising grains of superhard material and grains of a metal carbide material dispersed in a metal binder material.