Multi-lip Drilling Tool Asymmetrical Cooling Ducts
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Solution Overview
Problem
Existing multi-edged drilling tools face challenges in reducing local thermal and mechanical overstressing, particularly in areas exposed to high stress during machining, which can lead to tool failure and reduced performance.
Innovation Solution
The use of an asymmetrical kidney-shaped cross-sectional contour for internal cooling channels, with specific radii of curvature and a concave curve behind the main cutting edge, enhances coolant/lubricant distribution and minimizes tensile stress peaks, allowing for increased material concentration and improved coolant delivery to critical areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional cooling channel cross-sections with consistently convex contours are used, then the tool structure is simple and easy to manufacture, but tensile stress peaks occur in the flute base and coolant delivery to critical areas is insufficient
Solution Approach 1:
The patent applies asymmetry by introducing a concave curve section in the cooling channel cross-section that creates an asymmetrical kidney shape. This asymmetrical design redistributes material density and stress concentration points, effectively reducing tensile stress peaks in the flute base while maintaining structural integrity. The concave section specifically targets stress-prone areas without compromising overall tool strength.
Solution Approach 2:
The patent utilizes curvature principles by defining the cooling channel cross-section with specific radii of curvature for different sections. The concave curve section with its specific radius creates optimal stress distribution, while the convex sections maintain structural continuity. This controlled curvature approach transforms the stress field distribution, eliminating stress concentrations that would occur with simple convex shapes.
2Strength
If more material is concentrated behind the main cutting edge to reduce stress, then tool strength increases, but coolant delivery to the cutting edge may be compromised
Solution Approach 1:
The patent applies local quality by creating different cross-sectional characteristics in different regions of the cooling channel. The concave curve section is strategically positioned to concentrate material where stress is highest (behind the main cutting edge), while the convex sections maintain open pathways for coolant flow. This localized differentiation allows simultaneous optimization of both structural strength and coolant delivery without compromise.
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
This design effectively reduces stress peaks, ensures efficient coolant delivery to cutting edges, and enhances the strength of the tool, particularly when made from high-strength materials like solid carbide or cermet, by optimizing coolant flow and stress distribution, thereby improving tool durability and machining performance.
Implementation Method 1
as much coolant/lubricant as possible can be transported via the thinning and its intersection edges with the drill core to the drill core as quickly as possible main cutting edge or near it
Implementation Method 2
the distribution of stresses in the drill and the thermal load on the critical drilling tool areas are concerned
Data Source
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AI summary
A multi-lip drilling tool having internal cooling ducts and point grinding with point thinning is described, in which a main cutting edge transitions in the region of the drill web into a centre lip section, wherein a duct that leads to the drill tip is formed in each drill web. The cooling duct has the following characteristics, as seen in the cross section of the drill: a) it has the cross-sectional form of an asymmetrical kidney, wherein b) the largest circle (KE) substantially inscribed in the cooling duct cross section overlaps the centre of the drill webs () and bounds the contour of the cooling duct cross section via a central angle (WZKE) in the range between 80 and 90° in a radially external region (KEZW) facing away from the direction of rotation (); c) radially externally and in the cutting direction, the boundary curve (KEZW) defined by the inscribed circle (KE) is adjoined substantially in the circumferential direction by a cross-sectional contour section (BQ1) with a radius of curvature (R1) that is in the same direction as but considerably smaller than the inscribed circle (KE); d) the smaller radius of curvature (R1) of the cross-sectional contour section BQ1 transitions into a concave curve (KK) having a radius of curvature (R2) which is larger by a multiple than the curvature of the inscribed largest circle (KE); e) radially internally and outside the inscribed largest circle (KE), the concave curve (KK) is adjoined by a once again convex duct bulging section (AKA) having a radius of curvature (R3) which is much greater than the small radius of curvature (R1) in the cross-sectional contour section BQ1; and f) the curvature of the cross-sectional boundary increases continuously from the bulging section (AKA) to the region KEZW.