Internal Cryogenic Cooling Paths for Rotary Cutting Tools
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Solution Overview
Problem
Cryogenically cooled tools face challenges when machining materials with hexagonal lattice structures like Inconel, titanium, and cobalt, as the application of cryogenic fluids to the workpiece surface makes these materials tougher to machine, necessitating a more effective cooling method for the cutting tool itself.
Innovation Solution
A cooling flow path design where the coolant is channeled internally through the tool, following its outer shape, with radial bores and longitudinal grooves that direct the coolant close to the cutting edges and exhaust it remotely from the workpiece, utilizing cryogenic coolants like liquid nitrogen to maintain low temperatures and prevent workpiece cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cryogenic coolant is sprayed on the workpiece surface, then cooling effect is achieved, but the workpiece material becomes tougher and more difficult to machine
Solution Approach 1:
The patent extracts the cooling function from the workpiece surface and relocates it to the cutting tool itself. By incorporating internal coolant passages and exhaust ports within the tool body, the cooling effect is separated from direct contact with the workpiece, preventing the workpiece material from toughening while still achieving effective cooling at the cutting edge.
Solution Approach 2:
The cutting tool serves as an intermediary between the cryogenic coolant and the cutting zone. The coolant is delivered through internal passages to the cutting edge, and the exhaust ports positioned away from the workpiece surface act as intermediaries to discharge the coolant without allowing it to cool and toughen the workpiece material directly.
2Productivity
If cutting speed is increased, then productivity is improved, but heat generation at the cutting edge increases by 30%
Solution Approach 1:
The patent applies preliminary cooling action by delivering cryogenic coolant through internal passages to the cutting edge before excessive heat accumulates. The coolant is positioned at the cutting edge in advance, preventing heat buildup that would occur with conventional cooling methods, thereby enabling sustained high cutting speeds without temperature excursions.
Solution Approach 2:
The patent utilizes fluid dynamics by employing cryogenic coolant flowing through internal passages and exhaust ports. The controlled flow of coolant through the tool's hydraulic/pneumatic system delivers cooling precisely where needed at the cutting edge, managing heat generation that accompanies increased cutting speeds and productivity.
3Temperature
If conventional coolant delivery is used, then cooling is provided, but the coolant does not follow the tool's outer shape and cannot reach cutting edges effectively
Solution Approach 1:
The patent implements nesting by placing internal coolant passages and exhaust ports within the tool body structure itself. The coolant flow path is nested inside the tool's outer shape, allowing the cooling system to conform to and follow the tool's geometry while delivering coolant directly to the cutting edges without external cooling equipment.
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 allows for a significant increase in cutting speed, reducing heat at the cutting edge by 30%, enabling the tool to operate twice as fast without exceeding original temperatures, thus cutting material in half the time.
Implementation Method 1
The coolant is delivered through a coolant delivery path formed within the body of the cutting tool to a location close to the cutting edges
Implementation Method 2
The centrifugal force developed by the rotating tool will force the coolant from the coolant cavity to the outermost ends of the radial bores
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
A rotating cutting tool that iscylindlly cooled by cryogenic coolant, the rotating cutting tool has a cylindrical body including: a central bore that extends along a longitudinal axis of the cylindrical body; a plurality of cold flow delivery paths formed from radial bores that fluidly communicate with and extend radially-outwardly from the central bore; longitudinal grooves that are formed along an outer surface of the cylindrical body extending along the longitudinal axis and fluidly communicating with the radial bores; a bushing having an inner diameter closely conforming to the outer surface of the cylindrical body allowing the bushing to concentrically fit over the cylindrical body and the longitudinal grooves to form longitudinal passageways extending from the radial bores to one or more exhaust ports formed in the bushing proximate a rear face of the cylindrical body; and a plurality of cylinder for cutting a workpiece each having a cutting edge formed from the bushing.