Exchangeable-Head Twist Drill for Defined Blindhole Cone Bottoms
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Solution Overview
Problem
Existing twist drills for chip removing machining often produce blindholes with wavy bottom profiles, which are not well-defined, posing challenges for applications like hydraulic or pneumatic couplings where precision is required.
Innovation Solution
A twist drill with a concave main rake face and cutting edges contained within an imaginary conical surface, enhancing cutting performance and chip evacuation to generate a smooth, well-defined inverted cone bottom profile, suitable for precision drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If curved cutting edges are provided to enhance cutting performance and chip evacuation, then cutting speed and tool life are improved, but the bottom profile of the blindhole becomes wavy instead of well-defined
Solution Approach 1:
The cutting edges are configured to follow a curved line that lies on an imaginary conical surface, creating a specific geometric relationship between the cutting edge curvature and the resulting blindhole bottom profile. This curvature principle transforms the wavy bottom profile into a well-defined inverted cone shape while maintaining the benefits of curved cutting edges for chip evacuation and cutting performance
Solution Approach 2:
The invention changes the geometric parameters of the cutting edge configuration by constraining it to lie on an imaginary conical surface with specific dimensions. This parameter change allows the cutting edge to maintain its curved shape for improved cutting performance while simultaneously achieving a well-defined bottom profile through the specific conical geometry
2Object-generated harmful factors
If curved cutting edges are provided to improve chip evacuation, then chip removal is enhanced, but the bottom profile of the blindhole becomes wavy instead of well-defined
Solution Approach 1:
The cutting edges follow a curved line on an imaginary conical surface, which optimizes the chip evacuation function while controlling the bottom profile formation. The curvature allows chips to be efficiently removed along the helical chip flutes while the conical surface constraint ensures a well-defined inverted cone bottom profile is generated
3Productivity
If the main rake face has a concave shape to enhance cutting performance, then cutting speed increases, but the complexity of the tool geometry increases
Solution Approach 1:
The invention specifies that the main rake face has a concave shape with a radius of curvature within a particular range (at least 1.5 times as large as the twist drill radius). This parameter specification optimizes cutting performance while providing clear manufacturing guidelines that balance the increased geometric complexity with practical manufacturability
Data Source
AI summary
A twist drill and an exchangeable head for a twist drill, the twist drill extending along a central axis of rotation and having a front end formed as a drill point with two cutting edges and at least two clearance surfaces. Two helical chip flutes conduct chips away from the cutting edges. Each cutting edge extends in a transition between the clearance surfaces. One of the chip flutes extends from an inner position adjacent to the central axis to a peripheral envelope surface and has a main portion closest to the peripheral envelope surface. Each chip flute is delimited by a side surface including a main rake face, which extends rearward from the main portion of the cutting edge. The cutting edges are contained in an imaginary conical surface, such that the twist drill is operable to generate a bottom profile having the shape of an inverted cone.