Composite Step Drill Bit for Longer Cutting Edge Life
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Solution Overview
Problem
Existing step drill bits are expensive to manufacture and have cutting tips and edges that wear out quickly, limiting their durability and effectiveness in drilling holes of various diameters in sheet metal or thin metal plates.
Innovation Solution
A step drill bit design featuring a body made of a less expensive material like low carbon steel or tool steel, with a cutting head and elongated cutting strip made of harder materials such as carbide, cermet, or diamond, joined using methods like brazing or mechanical connections, and manufactured using near net shape processes like metal injection molding to reduce waste and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire drill bit is made of hard material like carbide, then the cutting edges are more durable, but the manufacturing cost increases significantly
Solution Approach 1:
The patent applies different materials to different parts of the drill bit based on their specific functional requirements. The cutting head and cutting strip are made of hard material (carbide, cermet, or diamond) to provide durability at the cutting edges, while the body is made of less expensive material (high speed steel, tool steel, or low carbon steel) to reduce overall manufacturing cost. This localized material selection resolves the contradiction between durability and cost.
Solution Approach 2:
The drill bit is constructed as a composite structure combining multiple materials with different properties. The cutting head and cutting strip use hard, wear-resistant materials to maintain cutting effectiveness, while the body uses more economical materials that provide sufficient structural support. This composite approach allows the drill bit to achieve the durability of hard materials at critical locations without the prohibitive cost of making the entire bit from hard material.
2Reliability
If carbide strips are used to extend cutting edge life, then durability improves, but manufacturing cost increases
Solution Approach 1:
Instead of using expensive carbide strips along the entire length of the drill bit, the patent applies hard material only to the cutting head and cutting strip portions that actually contact the workpiece. This localized application of hard material extends cutting edge life where it is most needed while avoiding the excessive cost of carbide strips throughout the entire bit length.
3Ease of manufacture
If traditional manufacturing methods are used, then production is straightforward, but material waste increases and cost rises
Solution Approach 1:
The patent employs near net shape manufacturing processes (such as metal injection molding or powder metal molding) to form the body and cutting head with minimal excess material. This preliminary shaping close to the final geometry reduces the need for subsequent material removal and minimizes waste, while still allowing for efficient production through standardized manufacturing processes.
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
The use of harder materials for the cutting head and strip increases the drill bit's life and durability while maintaining a cost-effective body material, enhancing performance without the need for expensive carbide strips, and reducing manufacturing costs through efficient near net shape production.
Implementation Method 1
a cutting tip configured to penetrate a workpiece
Implementation Method 2
The cutting head is formed of a second material having a greater hardness than the first material. The cutting strip is composed a third material having a greater hardness than the first material
Implementation Method 3
Each of the cutting tip and the cutting strip may be joined to the body by brazing, welding, adhesive, or mechanical connection
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
A step drill bit 10 includes a body 12 with a plurality of cylindrical steps 15 of increasing diameter from a front end 14 toward a rear end 16, a flute 22 extending from the front end toward the rear end, and cutting edges at junctions between each step and the flute. A cutting insert 25 with a hardness greater than the hardness of the body is coupled to the front end portion and at least partially defines a cutting head portion 26. The cutting head portion includes a center cutting tip 37, a cutting edge 35 extending radially outward from the cutting tip, a rake face 32 extending from the cutting edge toward the rear end portion, a relief face extending from the cutting edge in a circumferential direction opposite a rotational cutting direction of the drill bit, and a chip clearing recess 58 in communication with the flute, with the rake face facing the chip clearing recess.