Double-Margin Small-Diameter Drill Bit for Vibration Control
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Solution Overview
Problem
Elongated small-diameter drill bits with cutting blades of 2 mm or less and a margin-to-diameter ratio of 3 or more experience significant shaking during drilling, leading to decreased hole accuracy and increased risk of cutting blade breakage due to reduced rigidity.
Innovation Solution
A small-diameter drill bit design featuring symmetrically formed chip discharge grooves with cutting blades, first and second margin parts, and a thinning part, where the cutting blades have a difference in length of 0.04 mm or less, and the tip flank faces are configured to enhance rigidity and reduce cutting resistance imbalance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the drill bit is designed with small cutting blade diameter (2 mm or less) and large margin-to-diameter ratio (3 or more), then the drill bit can achieve elongated structure for deep hole drilling, but the rigidity of the cutting blade part becomes small leading to shaking and decreased hole accuracy
Solution Approach 1:
The cutting blade part is segmented into multiple cutting blades (typically two or more) arranged around the drill bit axis. Each cutting blade is supported by its own margin parts, distributing the structural support function across multiple elements. This segmentation allows the elongated drill bit to maintain rigidity through distributed support rather than relying on a single large-diameter cutting blade.
Solution Approach 2:
The margin parts are designed with specific local geometric features including rounded outer peripheral ends and controlled distances from heel parts. These local quality modifications concentrate support functions at critical locations where shaking occurs, enhancing rigidity at the cutting blade tips without compromising the overall elongated structure. The rounded ends and positioned margins create localized stress distribution that prevents shaking.
2Length of moving object
If the cutting blade part has small rigidity due to small diameter and large L/D ratio, then elongated structure is achieved, but shaking occurs during drilling leading to breakage of the cutting blade part
Solution Approach 1:
The margin parts are designed with rounded outer peripheral ends and specific distances from heel parts to create a cushioning effect before the cutting blades engage the workpiece. This beforehand cushioning absorbs shock and reduces impact forces on the cutting blades during drilling, preventing breakage. The rounded geometry acts as a buffer that mitigates sudden loads on the fragile small-diameter cutting blades.
Solution Approach 2:
The invention changes geometric parameters of the margin parts including the radius of rounded outer peripheral ends and the distance from heel parts. These parameter modifications optimize the structural performance of the cutting blade part, enhancing its ability to withstand drilling forces without breaking. By carefully controlling these dimensions, the design achieves both elongation and reliability.
3Stability of the object's composition
If four margin parts are used to support the cutting blade part, then shaking is suppressed to some extent, but hole accuracy still decreases remarkably due to the small rigidity of the cutting blade part
Solution Approach 1:
The margin parts are designed with specific local geometric features including rounded outer peripheral ends and controlled distances from heel parts. These local quality modifications concentrate support functions at critical locations where shaking occurs, enhancing rigidity at the cutting blade tips without compromising the overall elongated structure. The rounded ends and positioned margins create localized stress distribution that prevents shaking and maintains hole accuracy.
Solution Approach 2:
The margin parts are positioned asymmetrically with respect to the cutting blades, with specific distances from heel parts that are optimized for performance. This asymmetric arrangement allows the margin parts to provide support at critical locations while maintaining the necessary rigidity for accurate hole drilling. The asymmetric positioning creates optimal leverage and support geometry that enhances both stability and precision.
Data Source
AI summary
In this small-diameter drill bit, two cutting blades having main cutting blades, of which a difference between lengths are 0.04 mm or less, are formed on a tip of a double-margin drill bit body having a diameter of 2 mm or less and a margin length/diameter ratio of 3 or more. Two tip flank faces are formed such that a first extension line extending from a linear first intersecting ridgeline between a first tip flank face and a second tip flank face of one of the flank faces to the linear first intersecting ridgeline of the other flank face is located on a side in the drill bit rotation direction with respect to the other linear first intersecting ridgeline. A distance between the first extension line and the linear first intersecting ridgeline is in a range of 0.04 mm-0.08 mm.