Machine Tool Spindle Cooling Structure for Leak-Free Draw Bar Integration

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Solution Overview

Problem

Existing spindle cooling devices cannot effectively cool spindles with integrated draw bars, leading to coolant leakage issues.

Innovation Solution

A spindle device design that incorporates a hollow housing with annular and helical coolant passages, along with a draw bar system, allows for effective cooling without direct coolant flow, utilizing seal members to prevent leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If coolant is flowed directly through the spindle to cool it, then cooling effectiveness is improved, but coolant leakage occurs

Engineering Contradiction:
Improvespindle temperatureVSAvoidcoolant leakage prevention
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent introduces a boss member as an intermediary component between the coolant supply and the spindle. The coolant flows through the boss member (which has cooling passages) rather than directly through the spindle, thereby mediating the cooling process and preventing direct coolant-spindle contact that causes leakage. The boss member acts as a buffer and seal interface, resolving the contradiction between effective cooling and leakage prevention.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The cooling system is segmented into separate functional zones: the boss member contains the coolant passages and sealing interfaces, while the spindle contains the tool clamping mechanism. This segmentation allows the coolant flow path to be optimized for cooling effectiveness while the spindle structure remains optimized for tool holding, with the draw bar positioned in the spindle without interfering with the cooling function.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If a draw bar is installed in the spindle for tool clamping, then tool mounting capability is improved, but cooling becomes impossible

Engineering Contradiction:
Improvetool clamping capabilityVSAvoidspindle cooling capability
Core Design Contradiction:
Adaptability or versatilityVSTemperature

Solution Approach 1:

The system is divided into two independent subsystems: the draw bar clamping subsystem within the spindle and the boss member cooling subsystem. The draw bar operates axially within the spindle to clamp tools, while the cooling passages are located in the boss member surrounding the spindle. This segmentation allows both tool clamping and cooling to function simultaneously without interference.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The boss member serves as an intermediary structure that provides cooling functionality without interfering with the draw bar clamping mechanism. The cooling passages in the boss member are positioned to cool the spindle externally, allowing the draw bar to perform its clamping function internally without blocking coolant flow or heat dissipation paths.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If coolant passages are designed to flow through the spindle, then cooling effectiveness is improved, but structural complexity increases

Engineering Contradiction:
Improvecooling effectivenessVSAvoidspindle structure complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The cooling passages are extracted from the spindle structure and relocated to the boss member. This extraction simplifies the spindle structure by removing complex internal coolant channels, seals, and associated components from the spindle itself. The cooling function is maintained through the boss member's passages, which are easier to design and manufacture separately from the precision spindle assembly.

Inventive Principle:
Principle #2Taking out (Extraction)

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 design ensures reliable cooling of the spindle while preventing coolant leakage, effectively managing heat generated by bearings and seals during rotation.

Implementation Method 1

coolant flowing within the fixed shaft to cool the fixed shaft

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

seal members to prevent leakage

Methodology Applied
Scientific EffectMechanical sealing: Mechanical Fastener

Data Source

PatentEP3593943B1Main spindle device for machine tool
Publication Date: 2024.08.07 MAKINO MILLING MASCH CO LTD
  • EP3593943B1 patent drawingFigure 1
  • EP3593943B1 patent drawingFigure 2
  • EP3593943B1 patent drawingFigure 3

AI summary

A main spindle device (100) for a machine tool (10) has a hollow main spindle (104), which is supported by a housing (102) such that the hollow main spindle can rotate. The main spindle device is provided with: an annular cylinder (128), which is fixed to the housing, and is formed extending into the main spindle, said annular cylinder having an opening formed in the axis line direction of the main spindle; and a cooling path (144) formed on the outer circumferential surface of the cylinder to face the inner circumferential surface of the main spindle.