Dual-Channel CO2 Tool Cooling to Prevent Dry Ice Blockage

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Solution Overview

Problem

Current cooling and lubrication systems for machining processes, particularly for difficult-to-cut materials, are either ineffective or require specific ad-hoc designs that cannot be adapted to various machining processes and machine tools, and they often face issues with dry ice formation in CO2 regulation systems.

Innovation Solution

A portable device that simultaneously injects CO2 in liquid state and cutting fluid micro-particles, or either alone, into the machining area, using a CO2 regulation system that prevents dry ice formation and is controlled by a Programmable Logic Controller (PLC) for flexible operation in milling, lathing, and drilling processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If CO2 is used as cutting fluid in machining processes, then cooling capacity is improved, but dry ice formation obstructs the conduits

Engineering Contradiction:
Improvecooling capacityVSAvoidconduit obstruction
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The conduit is divided into two separate channels: an inner channel for liquid CO2 injection and an outer channel for gaseous CO2 injection. This segmentation allows the gaseous CO2 to counteract the formation of dry ice particles in the inner channel, preventing conduit obstruction while maintaining high cooling capacity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Gaseous CO2 acts as an intermediary substance that interacts with the liquid CO2 in the inner channel. The gaseous CO2 provides a protective atmosphere that prevents the phase transition of liquid CO2 to solid dry ice particles, thereby preventing conduit blockage

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a regulation system is designed to prevent dry ice formation, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improveconduit obstruction preventionVSAvoidregulation system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The regulation system merges the cooling function (liquid CO2 injection) and the anti-obstruction function (gaseous CO2 injection) into a single integrated device. The two channels are joined at the exit to form a unified injection system, simplifying the overall structure while maintaining reliability

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The dual-channel conduit serves multiple functions: the inner channel provides cryogenic cooling, the outer channel prevents dry ice formation, and together they create a universal regulation system that can be applied to various machining operations without requiring separate systems

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Manufacturing precision

If a cooling and lubrication device is designed for specific machining processes, then manufacturing precision is improved, but adaptability decreases

Engineering Contradiction:
Improvecooling and lubrication effectivenessVSAvoidapplicability to different machining processes
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The device is designed with independent control of cooling (liquid CO2) and lubrication (cutting fluid) functions, allowing it to be adapted to various machining processes such as milling, turning, and drilling. The system can operate in different modes (cooling only, lubrication only, or combined) to suit different machining requirements

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Reliability

If cooling and lubrication are provided separately, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improveindependent operationVSAvoidsystem integration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The device merges the separately controllable cooling and lubrication functions into a single integrated system. The cooling subsystem (liquid CO2) and lubrication subsystem (cutting fluid injection) are combined in one device with a unified injection mechanism, reducing overall system complexity while maintaining the ability to operate independently or simultaneously

Inventive Principle:
Principle #5Merging (Combining)

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 device provides continuous and controlled cooling and lubrication, adaptable to different machining operations, preventing dry ice obstruction and allowing simultaneous use of cryogenic cooling and minimum quantity lubrication (MQL), resulting in efficient temperature control and extended machine tool life.

Implementation Method 1

The gases that are normally injected in the cutting area are liquid nitrogen (LN 2 ) and liquid carbon dioxide (CO 2 ). The reasons for using LN 2 as cutting fluid are that it is an inert gas that is found in large amounts in the atmosphere and has high cooling capacity (-196°C)

Methodology Applied
Scientific EffectCryogenic cooling: Cryogenics

Implementation Method 2

Both conduits are joined just at the exit of the system, so the CO 2 in gaseous state generates a Venturi effect that drags the dry ice particles to the outside, thereby obtaining the cutting fluid to inject in the cutting area

Methodology Applied
Scientific EffectVenturi effect: Venturi Effect

Implementation Method 3

CO 2 has lower cooling capacity (-78°C), can be stored in liquid state at room temperature in pressurised containers at 5.5 - 6 MPa and can dissolve oils when it is in supercritical state, which makes it more attractive from an industrial point of view

Methodology Applied
Scientific EffectSupercritical fluid dissolution: Supercritical Fluid

Implementation Method 4

The device has been designed so it can adapt to the most common machining processes... using a CO2 regulation system that prevents the formation of dry ice

Methodology Applied
Scientific EffectPhase change prevention: Phase Change

Data Source

PatentEP3248730B1Device and method for cooling and lubricating tools in machining processes
Publication Date: 2021.05.19 FUNDACION TECNALIA RESEARCH & INNOVATION
  • EP3248730B1 patent drawingFigure 1A
  • EP3248730B1 patent drawingFigure 1B
  • EP3248730B1 patent drawingFigure 1C

AI summary

A device (100) for cooling and lubricating a tool during a chip removal machining process, which comprises: a first subsystem (110) for cryogenic cooling that comprises: a first entry (1) configured to introduce CO2 in liquid state in a first conduit (a) of the device (100); a first exit (18) configured to supply CO2 in liquid state from a second conduit (g) of the device (100); a third conduit (b) located between said first (a) and second conduit (g); and means (2, 7, 8, 4, 11, 13, 14, 15, 16, d, h, c) for preventing the formation of dry ice in said first, second and third conduits (a, g, b); and a second subsystem (120) for lubrication that comprises means (3, 5, 6, 9, 10, 12, 19, i, j, f, k, e, 20) for supplying micro-particles of a cutting oil in liquid state; wherein said first subsystem (110) and second subsystem (120) are independent from each other, and wherein said first subsystem (110) and second subsystem (120) are configured to act either simultaneously or either one alone (110, 120). Method of operation of the device.