Spindle Cooling Circuit Segmentation for Thermal Control

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Solution Overview

Problem

Existing spindle devices face challenges in achieving effective and reliable cooling, especially at high speeds, as they often require complex constructions and are susceptible to vibrations, with coolant supply methods that either inadequately cool the spindle or complicate tool cooling, and require continuous compressed air to prevent contamination.

Innovation Solution

A spindle device with internal closed cooling channels that allow coolant to be supplied to all bearing points and the rotor, enabling independent tool cooling, while using a gap seal and contact seal configuration to maintain a wear-free and non-contact seal during operation, ensuring efficient cooling and reduced vibrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If coolant is supplied via the pull rod to cool the spindle, then the spindle cooling is achieved, but the construction becomes complicated due to the need for compressed air supply at various sealing points

Engineering Contradiction:

Improvespindle temperatureVSAvoidconstruction complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The cooling system is segmented into two independent paths: one through the pull rod for tool cooling and another through the spindle housing for spindle cooling. This segmentation eliminates the need for compressed air sealing in the pull rod, simplifying the construction while achieving both cooling functions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spindle housing acts as an intermediary coolant supply path, delivering coolant directly to the spindle bearings and rotation axis without requiring the pull rod to serve dual cooling functions. This intermediary path eliminates the complexity of sealing requirements.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If coolant supply via the central channel of the pull rod is used to cool the tool, then tool cooling is achieved, but the spindle can only be operated with coolant supply to the tool, which is sometimes undesirable

Engineering Contradiction:

Improvetool temperatureVSAvoidoperational flexibility

Core Design Contradiction:

TemperatureVSAdaptability or versatility

Solution Approach 1:

The coolant supply system is divided into two independent channels: one through the pull rod for tool cooling and another through the spindle housing for spindle cooling. This allows independent control of coolant supply to each component, providing operational flexibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spindle housing is given the additional function of serving as a coolant supply path, making the system multi-functional. This allows the system to adapt to different operational requirements by selectively activating either the tool cooling path, the spindle cooling path, or both.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If a gap seal is used with air as the sealing pressure medium, then sealing is achieved, but residual coolant can get inside the spindle if the supply of pressure medium is not constantly maintained

Engineering Contradiction:

Improvesealing reliabilityVSAvoidcontinuous operation requirement

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The spindle housing serves as an intermediary coolant supply path that eliminates the need for gap seals and compressed air pressure medium. By providing a direct coolant delivery route to the spindle, the system removes the sealing vulnerability associated with gap seals.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system transitions from using pneumatic pressure medium (compressed air) for sealing to using hydraulic coolant delivery through the spindle housing. This eliminates the need for continuous pressure medium supply to maintain sealing.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 spindle device achieves effective cooling up to 30°C, reduces thermal expansion, and minimizes coolant usage, allowing for quicker startup and reduced vibrations, with a simpler construction that maintains reliability and tool-side rigidity.

Implementation Method 1

coolant flow through a plurality of closed cooling channels which extend through the spindle shaft (16), the pull rod (18) and the rotary feedthrough (36)

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

using a gap seal and contact seal configuration to maintain a wear-free and non-contact seal during operation

Methodology Applied

Scientific EffectSealing:

Data Source

PatentEP1736277B1Spindle device with through coolant and closed spindle cooling circuit running through a rotary coupling

Publication Date: 2008.07.02 FISCHER AG(CH)

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AI summary

The spindle unit is provided with an interior cooling system apart from the exterior system, both of them comprising coolant ducts guided through a rotating union. The interior coolant is guided through duct segments (88) beside the pulling rod (18) to pockets (86) between spindle shaft (16) and pulling rod (18), along the outer surface of the pulling rod (18) to a cylindrical sleeve serving as a return element (80), and back along the opposite side (84,92) of the arrangement.