Segmented Cutting Drill for Printed Wiring Board Holes
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Solution Overview
Problem
Conventional cutting drills for printed wiring boards face challenges in maintaining cutting edge accuracy and reducing processing costs due to the need for frequent repolishing and limited lifespan, especially when forming small holes, which affects productivity and surface quality.
Innovation Solution
A cutting drill design featuring a shank with a rotating drill body having a tip cutting-edge portion and a neck portion with a smaller diameter, where the cutting-edge portion is formed with a first and second cutting-edge portion contiguous through a step portion, allowing for reduced contact area and extended lifespan through sequential polishing and exposure of secondary cutting-edge portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rod-shaped drill section with constant diameter is used, then the structure is simple and easy to manufacture, but the contact area with the hole inner-wall surface is large causing high cutting resistance and reduced lifespan
Solution Approach 1:
The drill section is segmented into multiple cutting-edge portions (first, second, and third cutting-edge portions) with different diameters along the axial direction. This segmentation allows different portions to be sequentially used, extending the drill's operational life by enabling repolishing and reuse of subsequent cutting edges when earlier ones wear out.
Solution Approach 2:
The drill transitions from a static constant-diameter structure to a dynamic multi-diameter structure where different cutting-edge portions can be selectively activated. The varying diameters create different contact areas with the workpiece, allowing optimization of cutting resistance and lifespan through sequential use of first, second, and third cutting-edge portions.
2Manufacturing precision
If the drill section diameter is reduced to form smaller holes, then hole size requirement is met, but cutting resistance increases and cutting edge dulls faster
Solution Approach 1:
Different portions of the drill section have different local qualities in terms of diameter. The first cutting-edge portion has a larger diameter for initial cutting, while subsequent cutting-edge portions have progressively smaller diameters. This local variation allows the drill to maintain precise small hole dimensions while distributing wear across multiple portions, extending overall lifespan.
3Manufacturing precision
If frequent repolishing is performed to maintain cutting accuracy, then surface quality is maintained, but processing time increases and productivity decreases
Solution Approach 1:
The drill is pre-configured with multiple cutting-edge portions of varying diameters during manufacturing. This preliminary action ensures that when the first cutting-edge portion wears out, subsequent portions are already positioned and ready for use, eliminating the need for extensive repolishing operations and maintaining productivity.
4Device complexity
If a single cutting-edge portion is used, then the structure is simple, but the drill must be replaced frequently increasing costs
Solution Approach 1:
The drill design enables discarding of worn cutting-edge portions and recovering of cutting functionality through sequential use of remaining portions. When the first cutting-edge portion is exhausted, the drill can continue operation using second and third cutting-edge portions, effectively recovering the tool's value and reducing replacement frequency and costs.
Data Source
AI summary
A cutting drill includes a shank having a hole and formed to be gripped in a tool holder, and a drill body having a rod shape and locked into the hole of the shank. The shank has an axis around which the drill body rotates. The drill body has a cutting-edge portion forming a tip portion of the drill body and a neck portion having a diameter smaller than a diameter of the cutting-edge portion. The cutting-edge portion has a first cutting-edge portion and a second cutting-edge portion formed between the first cutting-edge portion and the neck portion. The first cutting-edge portion is contiguous to the second cutting-edge portion by a step portion such that the second cutting-edge portion has a diameter which is smaller than a diameter of the first cutting-edge portion.