Chuck Jaw Keyway Alignment for High Centering Accuracy

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Solution Overview

Problem

Conventional chucks face challenges in maintaining high centering accuracy after attaching or detaching the top jaw, due to circumferential displacement caused by gaps between the T-nut and keyways, and require complex structures and high manufacturing accuracy.

Innovation Solution

A chuck design with a connecting member and keyway system where the key is inclined or twisted to reduce gaps between the first and second keyways, allowing for close contact and minimizing circumferential displacement, maintaining high centering accuracy with a simpler structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a T-nut and keyway system is used to attach the top jaw to the master jaw, then the top jaw can be detachably attached, but gaps between the T-nut and keyways cause circumferential displacement reducing centering accuracy

Engineering Contradiction:
Improvedetachable attachment capabilityVSAvoidcentering accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

A connecting member is introduced as an intermediary component between the master jaw and top jaw. This connecting member includes a key that fits into keyways on both jaws, serving as a mediator to transmit positioning information and prevent circumferential displacement while allowing detachable attachment.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The keyway on the top jaw is designed with a preliminary inclined surface that guides the key into proper alignment during attachment. This preliminary action ensures the key enters the keyway at the correct angle and position, eliminating gaps and preventing circumferential displacement before the final tightening occurs.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If conventional keyways with gaps are used, then the structure is simple and easy to manufacture, but circumferential displacement occurs reducing centering accuracy

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcentering accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The keyway includes a preliminary inclined surface that guides the key into proper alignment during attachment. This preliminary action ensures the key enters the keyway at the correct angle and position, eliminating gaps and preventing circumferential displacement before the final tightening occurs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The keyway geometry is changed from a conventional rectangular cross-section to an inverted T-shaped cross-section with an inclined surface. This parameter change allows the key to be guided into proper alignment while maintaining ease of manufacture, eliminating the need for complex precision machining.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the keyway is designed to eliminate gaps through complex structures, then centering accuracy is maintained, but the structure becomes more complex and costly

Engineering Contradiction:
Improvecentering accuracyVSAvoidstructural complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The keyway includes a preliminary inclined surface that guides the key into proper alignment during attachment. This preliminary action ensures the key enters the keyway at the correct angle and position, eliminating gaps and preventing circumferential displacement before the final tightening occurs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The keyway geometry is changed from a conventional rectangular cross-section to an inverted T-shaped cross-section with an inclined surface. This parameter change allows the key to be guided into proper alignment while maintaining ease of manufacture, eliminating the need for complex precision machining.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3650151B1chuck
Publication Date: 2022.01.19 KITAGAWA IRON WORKS CO LTD
  • EP3650151B1 patent drawingFigure 1
  • EP3650151B1 patent drawingFigure 2
  • EP3650151B1 patent drawingFigure 3

AI summary

Each jaw 2 includes a master jaw 20 with serrations 22a and a top jaw 50, with serrations 53a, to be fastened to a T-nut 30. The support groove 23 includes a first keyway 24 into which the key 30b is fitted, whereas the top jaw 50 includes a second keyway 54 into which a tip of the key 30b is fitted. A gap exists between the key 30b and each of the first keyway 24 and the second keyway 54. The key 30b is inclined or twisted with respect to both the first keyway 24 and the second keyway 54.