Tool Spindle Clamp Structure With Stopper-Limited Axial Load

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Solution Overview

Problem

Conventional tool spindle structures face design restrictions due to the thrust force for unclamping being solely borne by the bearing, limiting flexibility and axial displacement, and requiring careful load management to prevent bearing overload.

Innovation Solution

The tool spindle structure shares the thrust force for unclamping between the bearing and a stopper member, utilizing an angular bearing with a predetermined clearance to distribute axial loads and prevent further displacement, allowing for increased flexibility in design and axial movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the thrust force for unclamping is borne solely by the bearing, then the bearing structure is simple, but the design flexibility is restricted and axial displacement is limited

Engineering Contradiction:
Improvebearing structureVSAvoiddesign flexibility
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The thrust force bearing function is segmented between two components: the bearing handles radial loads and portions of axial loads, while the stopper member specifically handles axial displacement limits. This division allows each component to be optimized for its specific function, enhancing overall design flexibility without complicating the bearing structure itself.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The stopper member acts as an intermediary element between the tool spindle and the housing, providing a mechanical stop that limits axial displacement. This intermediary component protects the bearing from excessive axial loads while allowing controlled axial movement, thereby improving design flexibility without requiring the bearing to handle all thrust forces alone.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the thrust force for unclamping is borne solely by the bearing, then the structure is simple, but axial load management becomes restrictive

Engineering Contradiction:
ImprovestructureVSAvoidaxial load management
Core Design Contradiction:
Device complexityVSForce

Solution Approach 1:

The axial load management is segmented between the bearing and the stopper member. The bearing supports radial loads and shares axial loads during normal operation, while the stopper member engages to limit maximum axial displacement and protect the bearing from overload. This segmentation enables better axial load management without increasing overall structural complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The stopper member provides beforehand cushioning by being pre-positioned to limit axial displacement before excessive loads can damage the bearing. This protective arrangement is built into the structure in advance, allowing the bearing to operate within safe load limits without requiring complex active control mechanisms.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the bearing receives all thrust force in pushing direction, then the bearing provides sufficient support, but design flexibility for unclamping mechanism is reduced

Engineering Contradiction:
Improvebearing supportVSAvoidunclamping mechanism design
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The support function is segmented between the bearing (providing reliable radial and partial axial support) and the stopper member (providing axial displacement limiting). This segmentation maintains reliable bearing support while freeing the unclamping mechanism design from strict load management constraints, thereby improving design flexibility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The stopper member serves as an intermediary that protects the bearing from excessive thrust forces during unclamping operations. By placing this protective element between the tool spindle and housing, the bearing maintains reliable support without being overloaded, allowing for more flexible unclamping mechanism designs.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 configuration enhances design flexibility by distributing the unclamping force, protecting the bearing and allowing for greater axial displacement without overloading, thus enabling more robust and versatile tool spindle designs.

Implementation Method 1

a clamp spring 14 applies a biasing force to the clamp rod 13 in a pulling direction

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a bearing (angular bearing) 15 between the tool spindle 11 and the housing 12... the bearing includes an outer wheel fixed to the housing, an inner wheel fixed to the tool spindle, a rolling body therebetween

Methodology Applied
Scientific EffectRolling contact: Ball Bearing

Implementation Method 3

displacement of the tool spindle fixed to the inner wheel is restricted by the stopper member to prevent a further displacement of the inner wheel

Methodology Applied
Scientific EffectMechanical contact: Mechanical Force

Data Source

PatentEP3741503B1Tool spindle structure
Publication Date: 2024.01.17 NAKAMURATOME SEIMITSU IND
  • EP3741503B1 patent drawingFigure 1A
  • EP3741503B1 patent drawingFigure 1B~1C
  • EP3741503B1 patent drawingFigure 2

AI summary

A tool spindle structure causes a clamp rod (13) to retract to fix a tool to a tool spindle (11), the tool being mounted at a distal end portion of the tool spindle (11), and causes the clamp rod (13) to advance to unfix the tool from the tool spindle (11). The tool spindle (11) is supported in a housing (12, 12a, 12b) such that displacement thereof is allowed along an axial direction. A stopper member (16) restricts a displacement amount of the tool spindle (11) that is displaceable with an axial load applied to a bearing (15) by the advance of the clamp rod (13).