Drill Bit Insert with Segmented Hard Surface Layer
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Solution Overview
Problem
Drill bit inserts with a polycrystalline diamond hard surface layer wear prematurely due to exposure of the cemented carbide insert body surface when the outer diameter of the insert body is larger than the fitting hole, leading to reduced tool life and inadequate wear resistance utilization.
Innovation Solution
A drill bit insert design featuring a rear end portion with a columnar or disk-like shape, an intermediate portion with a smaller outer diameter, and a hard surface layer coating that extends from the end portion to the intermediate portion, ensuring the hard surface layer remains intact even when the outer periphery is polished, preventing exposure of the lower hardness insert body surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the outer diameter of the rear end portion of the insert body is formed larger than the inner diameter of the fitting hole, then the insert body can be securely attached to the drill bit, but the outer periphery of the end portion must be polished which removes the hard surface layer and exposes the insert body surface
Solution Approach 1:
The insert body is divided into three distinct portions along the center line: a rear end portion with larger outer diameter for secure attachment, an intermediate portion with medium outer diameter, and an end portion with smaller outer diameter for drilling. This segmentation allows each portion to serve its specific function while the hard surface layer is strategically positioned to cover the wear-prone end portion without interfering with the attachment of the rear end portion.
Solution Approach 2:
The hard surface layer is applied selectively to cover the end portion and intermediate portion of the insert body, but not the rear end portion. This local quality approach ensures that the hard surface layer provides wear resistance where needed (at the drilling end) while allowing the rear end portion to be polished for secure attachment without waste of the hard surface layer.
2Ease of manufacture
If the outer periphery of the drill bit insert is polished to bury the rear end portion in the fitting hole, then proper attachment is achieved, but the hard surface layer is removed and the insert body surface is uncovered
Solution Approach 1:
The insert body is pre-formed with a three-tiered diameter structure before the hard surface layer is applied. The rear end portion is designed with a larger diameter that will be polished during attachment, while the end portion has a smaller diameter that will remain exposed. This preliminary structuring ensures that polishing removes only the insert body material from the rear end portion and does not expose the insert body at the wear-prone end portion.
Solution Approach 2:
Instead of applying the hard surface layer uniformly across the entire insert body and then polishing (which would remove the hard surface layer), the invention inverts the approach by designing the insert body geometry first with differentiated diameters, then applying the hard surface layer only where needed. This reversal of the process sequence protects the hard surface layer from being removed during polishing.
3Reliability
If the hard surface layer is made thicker to prevent wear, then wear resistance is improved, but the outer diameter of the insert body increases requiring more extensive polishing
Solution Approach 1:
The hard surface layer is applied with controlled thickness only at the end portion and intermediate portion where wear resistance is needed, rather than uniformly across the entire insert body. The end portion receives the hard surface layer coating, while the rear end portion is left without hard surface layer to minimize polishing requirements and simplify the attachment process.
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 design extends the tool life of the drill bit insert and bit by maintaining the wear resistance of the polycrystalline diamond hard surface layer, preventing premature wear and breakage, and enabling efficient drilling.
Implementation Method 1
a hard surface layer coated on the insert body and made of a polycrystalline diamond, which is harder than the insert body
Implementation Method 2
polycrystalline diamond sintered material as described above, it is normal in a manufacturing method of such a drill bit insert that the thickness of the hard surface layer is thick at a tip of an end portion
Data Source
AI summary
In a drill bit insert of the present invention, an insert body of the drill bit insert includes: a rear end portion forming a columnar shape or a disk-like shape; an intermediate portion having an outer diameter smaller than that of the rear end portion; and an end portion having an outer diameter from the center line of the insert gradually decreasing toward the tip side, the hard surface layer is coated on the insert body from a surface of the end portion of the insert body to an outer periphery of the intermediate portion, and an outer diameter of the hard surface layer on the intermediate portion is equal to that of the rear end portion.