Adaptive R744 Cooling Lubrication System
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Solution Overview
Problem
Conventional R744 minimum quantity cooling lubrication (MQCL) systems face challenges in providing precise low-temperature cooling and efficient lubrication for machining processes, particularly in closed systems like portable drilling machines, due to issues such as dry ice build-up, lubricant freezing, inconsistent cooling effects, and excessive airborne oil aerosols, which hinder productivity and require extensive clean-up operations.
Innovation Solution
A dual-throttle, mixed-fluid R744 refrigeration system that uses supersaturated CO2 injection and a coaxial refrigeration tube to create a micronized fluid spray, combined with a superspreading lubricant composition that reduces surface tension and viscosity, enabling efficient cooling and lubrication with minimal lubricant usage and easy clean-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional R744 MQCL systems are used for cooling and lubrication, then cooling capacity is provided, but dry ice build-up and lubricant freezing occur
Solution Approach 1:
The patent changes the physical parameters of the CO2 system by using a refrigerated CO2 reservoir that maintains CO2 in a controlled liquid or supercritical state, preventing uncontrolled phase changes that cause dry ice build-up. The system adjusts temperature and pressure parameters to keep CO2 in a stable state during delivery
Solution Approach 2:
The patent controls phase transitions of CO2 by using a refrigerated reservoir to prevent uncontrolled vaporization. The system manages the CO2 phase change from liquid to gas in a controlled manner, preventing dry ice formation in the delivery channels while maintaining cooling capacity
2Force
If air-oil MQCL sprays are used, then lubrication is provided, but excessive fogging and limited cooling capacity occur
Solution Approach 1:
The patent changes the carrier fluid from air to CO2, which has different physical properties including higher density and better heat transfer characteristics. This parameter change reduces aerosol formation and fogging while improving cooling capacity
Solution Approach 2:
The patent uses a composite approach by combining CO2 with lubricant in a controlled mixture, where CO2 acts as both carrier and cooling agent. This composite system provides lubrication through the lubricant while CO2 minimizes fogging and enhances cooling
3Temperature
If water-based MQCL is used, then cooling is provided, but messy machining and extensive clean-up are required
Solution Approach 1:
The patent changes the coolant chemistry from water-based to CO2-based. CO2 is a gas at ambient conditions and leaves no liquid residue, eliminating the messy clean-up associated with water-based coolants while maintaining effective cooling through phase change and heat transfer
4Temperature
If conventional R744 MQCL is adapted to closed systems, then through-spindle cooling is achieved, but inconsistent cooling and lubrication occur due to varying machining conditions
Solution Approach 1:
The patent implements a dynamic control system with sensors that monitor machining conditions in real-time and adjust CO2 delivery parameters accordingly. The system can adapt flow rates, pressures, and temperatures to match varying cutting conditions, tool types, and material being machined
Solution Approach 2:
The patent incorporates feedback mechanisms where sensors detect machining zone conditions and feed this information back to the control system, which adjusts CO2 delivery to maintain optimal cooling and lubrication. This closed-loop control ensures consistent performance across varying machining conditions
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 system achieves precise cooling and lubrication, reducing machining temperatures, improving surface finishes, and minimizing clean-up efforts while being adaptable to various machining systems and tools, using safer and renewable chemistries in smaller quantities.
Implementation Method 1
The present invention employs a dual-throttle, mixed-fluid and open-cycle Refrigerant 744 (R744) refrigeration process comprising three stages—Stage 1: Charging, Stage 2: Infusion, and Stage 3: Release-Recycle
Implementation Method 2
The present invention employs a dual-throttle, mixed-fluid and open-cycle Refrigerant 744 (R744) refrigeration process comprising three stages—Stage 1: Charging, Stage 2: Infusion, and Stage 3: Release-Recycle
Data Source
AI summary
This application presents a method and apparatus for cooling a through-ported cutting tool with a source of liquid CO2 with a compressed air line with a compressed air inlet and multiple CO2 injection capillary segments; the capillary segments interconnect to the same source of liquid CO2 and can have high pressure valves and throttles; the throttles have different sizes; a first capillary ends near the cutting tool; the second capillary ends near the compressed air inlet. Using a particular sequence of opening or closing the valves to the liquid CO2 to the capillaries, mixing with the compressed air provides and recycling the residual CO2, this invention provides for uniform and controlled cooling of the cutting tool within a certain temperature range.