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 challenging 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 finished component, but the cutting resistance is high and productivity is low
Solution Approach 1:
The patent applies preliminary action by performing drilling on the green body before sintering. The green body has weaker bonding between metal powder particles compared to the sintered component, making it easier to drill with lower cutting resistance. The hole is formed in advance, and subsequent sintering processes preserve the hole structure while strengthening the surrounding material.
2Productivity
If drilling is performed on a powder-compact green body before sintering, then productivity is improved and cutting resistance is reduced, but edge chipping occurs on the hole opening
Solution Approach 1:
The patent applies spheroidality by forming a rounded hole bottom through controlled drilling parameters. The circular-arc shaped cutting edge of the drill creates a hemispherical bottom at the hole exit side, which prevents stress concentration and eliminates edge chipping. This curved geometry distributes the thrust load evenly, maintaining edge quality while enabling productive drilling of green bodies.
3Force
If a V-shaped cutting edge is used for drilling, then the drill can penetrate the material, but edge chipping occurs due to concentrated thrust load
Solution Approach 1:
The patent replaces the V-shaped cutting edge with a circular-arc shaped cutting edge that creates a rounded hole bottom. This curved geometry distributes the thrust load around the hole perimeter rather than concentrating it at the vertex, preventing edge chipping while maintaining effective penetration capability through the green body.
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 improved precision and surface finish.
Implementation Method 1
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.