Green Body Drilling With Arc-Edge Drill to Prevent Hole Chipping
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Solution Overview
Problem
Drilling through-holes in sintered components is difficult due to high cutting resistance and tool wear, leading to low productivity and edge chipping issues, as the strong bonding between metal powder particles makes it hard to form precise holes without burrs.
Innovation Solution
Perform drilling on a powder-compact green body before sintering using a drill with a circular-arc shaped cutting edge, which reduces cutting resistance and suppresses edge chipping by dispersing the thrust load and maintaining the strength of the hole bottom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If drilling is performed on a sintered component after sintering, then the through-hole can be formed in the final product, but the cutting resistance is high and tool life is decreased
Solution Approach 1:
The patent applies preliminary action by performing drilling on the green body (powder compact) before sintering. The green body has lower strength and bonding between particles, making drilling easier with lower cutting resistance. The hole is formed in advance when the material is more compliant, avoiding the high cutting resistance encountered when drilling the hardened sintered component.
2Productivity
If drilling is performed on a powder-compact green body before sintering, then cutting resistance is reduced and productivity is improved, but edge chipping occurs on the opening edge
Solution Approach 1:
The patent applies spheroidality by forming a rounded opening edge instead of a sharp edge during drilling of the green body. The circular-arc shaped cutting edge of the drill creates a curved transition at the opening, which prevents stress concentration and eliminates the need for subsequent edge processing. This curved geometry inherently suppresses edge chipping while maintaining good surface quality.
3Speed
If a V-shaped cutting edge is used for drilling, then the drill can penetrate the material, but burrs occur on the exit side due to high thrust load
Solution Approach 1:
The patent uses a circular-arc shaped cutting edge instead of a V-shaped edge. This curved geometry distributes the cutting forces more evenly and reduces the concentrated thrust load at the tip. The rounded contact area prevents the material from being pushed out violently, eliminating burr formation on the exit side while maintaining effective penetration capability.
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 method enhances productivity by reducing machining time and tool wear, while minimizing edge chipping and burr formation, resulting in a sintered component with a satin finish and improved precision.
Implementation Method 1
When drilling is performed on the powder-compact green body, cutting can be easily performed and also a cutting resistance (thrust loaf) can be significantly reduced, since bonding between metal powder particles thereof is weak. When drilling is performed on the powder-compact green body, a through-hole is formed as metal powder particles are cut while being scrapped by the drill.
Implementation Method 2
The sintered component is hard, since metal powder particles therein are diffusion-bonded and alloyed with each other by sintering, thereby forming a strong bonding therebetween.
Data Source
AI summary
Provided is a method for manufacturing a sintered component, which can suppress occurrence of edge chipping when a through-hole is formed in a powder-compact green body and also has a good productivity. The method for manufacturing a sintered component includes a molding step of press-molding a raw material powder containing a metal powder and thus fabricating a powder-compact green body; a drilling step of forming a hole in the powder-compact green body using a drill; a sintering step of sintering the powder-compact green body after drilling, wherein the drill used for drilling has a circular-arc shaped cutting edge on a point portion thereof.