Lathe Chuck Jaw Structure for Stable Workpiece Support

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Solution Overview

Problem

Existing chuck designs for lathes suffer from distortions and deformations when supporting workpieces due to the concentration of forces on relatively small contact areas, leading to inaccurate and unstable support.

Innovation Solution

A chuck design featuring a body with keyways having a wider sliding surface area and master jaws with a wider sliding surface that comes into surface contact with the keyways, distributing forces more evenly and reducing the likelihood of distortions and deformations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the contact area between the keyways and sliding surfaces is kept small, then the structure remains simple, but distortions and deformations occur in the master jaws and body

Engineering Contradiction:
Improvestructure simplicityVSAvoiddistortions and deformations
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The keyways are designed with a wider sliding surface that serves multiple functions: it provides increased contact area to distribute forces and prevent deformations, while also guiding the sliding motion of the master jaws. This multi-functional design resolves the contradiction by making the same structural element serve both simplicity and stability requirements.

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

Solution Approach 2:

The sliding surface area is increased by expanding in the circumferential dimension rather than increasing the axial length. This dimensional change allows the contact area to be enlarged without significantly increasing the overall size or complexity of the keyway structure, thus preventing deformations while maintaining structural simplicity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the sliding surface area is increased to distribute forces, then support accuracy improves, but the device complexity increases

Engineering Contradiction:
Improvesupport accuracyVSAvoidsliding surface area
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The keyways are designed with a localized wider sliding surface area specifically at the contact regions with the master jaws. This local quality enhancement concentrates the force distribution benefit where it is most needed for support accuracy, without unnecessarily increasing the overall device complexity throughout the entire structure.

Inventive Principle:
Principle #3Local quality

3Device complexity

If the contact area between keyways and sliding surfaces is small, then the structure is simpler, but the support stability deteriorates

Engineering Contradiction:
Improvecontact areaVSAvoidsupport stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The keyways serve multiple functions simultaneously: they guide the radial sliding motion of the master jaws, provide increased contact area for force distribution, and prevent deformations. This multi-functional design achieves support stability without proportionally increasing device complexity.

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

Solution Approach 2:

The guiding function and force distribution function are merged into a single keyway structure with a wider sliding surface. Instead of having separate components for guidance and force distribution, the keyway integrates both functions, achieving support stability while minimizing additional complexity.

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 design provides stable and accurate support for workpieces by minimizing distortions and deformations in the master jaws and body, enhancing the overall support accuracy and stability.

Implementation Method 1

Due to the rearward draw of the plunger 103 and a wedge effect, the wedge 106 receives a radially inward force as indicated by the arrow N.

Methodology Applied
Scientific EffectWedge effect: Wedge

Data Source

PatentEP3708281B1chuck
Publication Date: 2023.04.26 KITAGAWA IRON WORKS CO LTD
  • EP3708281B1 patent drawingFigure 1
  • EP3708281B1 patent drawingFigure 2~3
  • EP3708281B1 patent drawingFigure 4

AI summary

A chuck includes a plurality of master jaws 20 that slide in the radial direction in the front surface of a body 10 in conjunction with slide of a plunger 40. The body 10 has a housing chamber 11 communicating with a plurality of keyways 13. The plunger 40 is fitted in the housing chamber 11. Each of the master jaws 20 includes a narrower part 21 and a wider part 22 fitted into an associated one of the keyways 13, and a wedge 23 connected to the plunger 40. The wider part 22 has a flat wider sliding surface 22b radially outside the wedge 23. Each of the keyways 13 has a wider slid surface 14.