Bore Clamp Wedge Drive for Efficient Workpiece Tensioning

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Solution Overview

Problem

Existing hole tensioners are not optimal in terms of drive efficiency for the clamping bolt, which affects the effectiveness of workpiece tensioning.

Innovation Solution

The hole tensioner features a clamping bolt drive with a laterally movable piston and a wedge surface gear, allowing for effective lateral movement conversion into axial movement of the clamping bolt, along with a cover cap to prevent contamination and a reset device for radial compression of the clamping socket.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a hydraulic piston drive is used for the clamping bolt, then the clamping force can be generated, but the drive efficiency and effectiveness of workpiece tensioning is not optimal

Engineering Contradiction:
Improveclamping forceVSAvoiddrive efficiency
Core Design Contradiction:
PowerVSProductivity

Solution Approach 1:

The patent replaces the hydraulic piston drive with a mechanically actuated wedge-shaped drive. The wedge-shaped drive element converts axial movement into radial expansion of the clamping sleeve, providing more efficient force transmission and better drive effectiveness for workpiece tensioning compared to the hydraulic system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the clamping sleeve is expanded radially to anchor it in the workpiece bore, then the clamping function is achieved, but the wedge surfaces may be exposed to contamination from the workpiece bore

Engineering Contradiction:
Improveclamping functionVSAvoidcontamination of wedge surfaces
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a protective coating to the wedge surfaces before they are exposed to the workpiece bore environment. This preliminary protective measure prevents contamination from affecting the friction-critical wedge surfaces during the clamping operation, maintaining reliable force transmission while allowing the clamping function to operate effectively.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If a wedge-shaped drive with sliding wedge surfaces is used to convert lateral piston movement into axial clamping bolt movement, then drive efficiency is improved, but friction and wear on the wedge surfaces occur

Engineering Contradiction:
Improvedrive efficiencyVSAvoidservice life of wedge surfaces
Core Design Contradiction:
ProductivityVSDuration of action of moving object

Solution Approach 1:

The patent replaces the sliding wedge surface mechanism with a ball-screw mechanism. The ball-screw drive converts the lateral movement of the drive element into axial movement of the clamping bolt through rolling contact between balls and screw threads, dramatically reducing friction and wear compared to sliding contact while maintaining high drive efficiency.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental interaction parameter of the drive mechanism from sliding friction to rolling contact. By introducing ball elements that roll between the screw thread and nut, the coefficient of friction is reduced from typically 0.1-0.2 for sliding contact to 0.002-0.005 for rolling contact, significantly extending the service life of the moving parts.

Inventive Principle:
Principle #35Parameter changes

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 the drive efficiency of the clamping bolt, improves contamination prevention, and ensures reliable radial compression of the clamping socket, thereby improving the overall effectiveness of workpiece tensioning.

Implementation Method 1

The clamping bolt drive (100) features a wedge-shaped drive with sliding wedge surfaces to convert the lateral movement of the piston into a corresponding axial movement of the clamping bolt (4) in the clamping direction. The wedge-shaped drive thus has a first wedge surface (10) on the laterally displaceable piston and a second wedge surface (13) that acts on the clamping bolt (4).

Methodology Applied
Scientific EffectWedge: Wedge

Data Source

PatentEP4003649B1Bore clamp
Publication Date: 2025.04.16 LUGWIG EHRHARDT GMBH
  • EP4003649B1 patent drawingFigure 1
  • EP4003649B1 patent drawingFigure 2~3
  • EP4003649B1 patent drawingFigure 4A~4B

AI summary

The invention relates to a bore clamp for clamping a workpiece with a workpiece bore located in the workpiece, having a radially expandable clamping bushing (1), a displaceable clamping bolt (4) for expanding the clamping bushing (1) in the clamping position, and a clamping bolt drive (5, 6, 10-13) for axially displacing the clamping bolt (4) into the clamping position. According to the invention, the clamping bolt drive (5, 6, 10-13) comprises a laterally displaceable piston (11) and a wedge surface drive (10, 13) with wedge surfaces (10, 13) sliding on top of one another for translating the lateral movement of the piston (11) into a corresponding axial movement of the clamping bolt (4) in the clamping direction.