Drill With Concave Negative Rake Surface for Ceramic Chip Discharge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional drills for cutting metal workpieces face challenges with chip flow and durability, particularly when cutting ceramic materials, as they tend to wear quickly and experience excessive temperature rises due to continuous chip engagement.
Innovation Solution
A drill design featuring a bar-shaped body with a cutting edge and a second surface having a negative rake angle, forming a concave shape, which enhances chip discharge and durability by allowing chips to flow easily towards the rear and reducing engagement with the cutting edge, thereby minimizing wear and temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional drill with positive rake angle is used, then cutting edge strength is improved, but chip discharge performance deteriorates and temperature rise increases
Solution Approach 1:
The patent inverts the conventional rake angle from positive to negative. The second surface is configured with a negative rake angle (−10° to −45°), which is opposite to the conventional positive rake angle. This inversion causes chips to flow toward the rear along the second surface instead of engaging continuously with the cutting edge, thereby resolving the contradiction between cutting edge strength and chip discharge performance.
Solution Approach 2:
The second surface is configured with a concave shape in cross-section orthogonal to the central axis. This curved geometry guides chips smoothly toward the rear and prevents chip clogging at the cutting edge, while maintaining the negative rake angle effect. The curvature works synergistically with the negative rake angle to improve chip discharge without compromising cutting edge strength.
2Productivity
If continuous chip engagement occurs, then material removal is achieved, but durability decreases due to excessive wear
Solution Approach 1:
By inverting the rake angle to negative, the patent changes chip flow direction from continuous engagement with the cutting edge to rearward flow along the second surface. This allows material removal to continue while preventing the continuous wear that reduces durability, thereby resolving the contradiction between productivity and reliability.
3Stability of the object's composition
If conventional rake surface design is used, then cutting edge stability is maintained, but chip flow causes excessive temperature rise
Solution Approach 1:
The negative rake angle inverts the chip flow direction, preventing chips from remaining in contact with the cutting edge and thereby reducing heat generation. The cutting edge stability is maintained through proper geometric configuration while temperature rise is reduced by changing the chip discharge path.
Solution Approach 2:
The concave shape of the second surface provides a curved path for chip flow that efficiently removes chips from the cutting zone. This curvature prevents chip accumulation and the associated temperature rise, while maintaining cutting edge stability through the overall geometric design.
Data Source
AI summary
In an embodiment, a drill includes a bar-shaped body rotatable around a central axis. The body includes a first surface located at a first end, a second surface intersecting with the first surface on a front side in a rotation direction, and a cutting edge located at an intersection of the first surface and the second surface. The second surface includes a first region located along the cutting edge, and a second region located on a front side in the rotation direction with respect to the first region. The second surface has a concave shape in a cross section orthogonal to the central axis.