Four-Jaw Chuck Drive for Centering Rectangular Workpieces

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Solution Overview

Problem

Existing clamping feeds for machine tools struggle to efficiently clamp workpieces with a rectangular but not square cross-section, requiring high effort and often using adapter pieces or differently set stamp cheeks for centering and clamping.

Innovation Solution

A clamping feed design featuring a drive with wedge rods that convert translational movement into radial movement of clamping cheeks, coupled with a rotating bracket unit and a coupling mechanism, allowing for precise centering and clamping of rectangular workpieces without adapter pieces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional chucks with four jaw guides are used, then workpieces with square cross-section can be clamped, but workpieces with rectangular (non-square) cross-section cannot be precisely centered and clamped without adapter pieces or manual adjustment

Engineering Contradiction:
Improveability to clamp rectangular workpiecesVSAvoidcentering effort
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent introduces a drive mechanism with wedge bars that can be adjusted to different positions, transforming a static chuck into a dynamic system. The wedge bars are movable along the jaw guides and can be positioned at different distances from the chuck axis, enabling the chuck to adapt to rectangular workpieces of various aspect ratios while maintaining precise centering through the coupled adjustment mechanism

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If differently adjusted clamping jaws are used to clamp rectangular workpieces, then clamping is possible, but the device complexity and adjustment time increase

Engineering Contradiction:
Improveclamping capability for rectangular workpiecesVSAvoidadjustment mechanism complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines the adjustment mechanisms for opposing jaw pairs through a coupled drive system. The wedge bars for opposing jaws are linked through the drive mechanism, so that adjusting one pair automatically adjusts the other pair in a coordinated manner. This merging of adjustment functions reduces the overall complexity compared to completely independent adjustments while maintaining the ability to clamp rectangular workpieces

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If adapter pieces are used to clamp rectangular workpieces, then clamping is achievable, but the device complexity and setup time increase

Engineering Contradiction:
Improveability to clamp rectangular workpiecesVSAvoidsetup time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent creates a universal chuck mechanism that can handle both square and rectangular workpieces without requiring separate adapter pieces. The drive mechanism with adjustable wedge bars provides multi-functionality, allowing the same chuck to adapt to different workpiece geometries by simply adjusting the wedge bar positions rather than changing components or adding adapters

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

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

Enables simple and efficient clamping of workpieces with a rectangular cross-section, ensuring precise centering and uniform clamping force across all four clamping jaws, even when their distances are different.

Implementation Method 1

a toothing on its front side which engages or can be brought into engagement with a corresponding counter toothing of a clamping jaw in order to convert a movement of the wedge bars into a radial movement of the clamping jaws

Methodology Applied
Scientific EffectMechanical Advantage: Mechanical Advantage

Implementation Method 2

the coupling mechanism is designed as a driver mechanism which comprises at least one driver element which is arranged eccentrically to the chuck axis in the control element and engages with the two drive rings

Methodology Applied
Scientific EffectEccentric mechanism: Eccentric

Data Source

PatentEP3738701B1Chuck for machine tools
Publication Date: 2025.04.30 SCHUNK GMBH & CO KG
  • EP3738701B1 patent drawingFigure 1
  • EP3738701B1 patent drawingFigure 2
  • EP3738701B1 patent drawingFigure 3

AI summary

Chuck (101) for machine tools, in particular lathes, comprising a chuck body (102) in the front face (103) of which four pairs of opposing guide grooves (104) are formed for receiving a clamping jaw (105a, 105b, 105c, 105d) each, extending radially to a central chuck axis (X), and a drive configured to adjust clamping jaws (105a, 105b, 105c, 105d) inserted in opposing guide grooves (104) in pairs together, wherein the drive comprises a wedge bar (109a, 109b, 109c, 109d) associated with each guide groove (104), which is guided translationally in a wedge bar pocket formed in the chuck body (102) extending transversely to the guide groove (104) and has a toothed section on its front face. (110) carries which engages or can be brought into engagement with a corresponding counter-toothing (111) of a clamping jaw (105a, 105b, 105c, 105d),to convert a movement of the wedge rods (109a, 109b, 109c, 109d) into a radial movement of the clamping jaws (105a, 105b, 105c, 105d).