Machining System Conical Nut Positioning

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Solution Overview

Problem

Existing machining systems face challenges in achieving precise longitudinal and angular positioning of machining bars within tool holders, leading to vibrations and uncertainty in positioning due to radial or concentric tightening methods, which limit rigidity and maintenance of the bar's position during machining operations.

Innovation Solution

A machining system with a tool holder and machining bar featuring a tightening nut with a conical portion that creates concurrent support forces, including a first support zone with a beveled surface and a second conical portion on the bar, allowing for precise longitudinal and angular positioning without radial tightening, and providing lateral clamping along the inner wall of the bore, thereby reducing stress and vibrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If radial or concentric tightening is used to hold the machining bar, then the bar can be secured in the bore, but vibrations and uncertainty of positioning occur during machining

Engineering Contradiction:
Improvepositioning stabilityVSAvoidvibrations
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The support function is segmented into multiple zones: a first support zone with a rear stop providing longitudinal support, and a second support zone with lateral support surfaces providing radial positioning. This segmentation allows each zone to specialize in its function, preventing vibrations while maintaining positioning stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the machining bar are given different qualities: the rear portion has a beveled face for longitudinal positioning against the rear stop, while the lateral surfaces in the second support zone are designed for radial positioning. This local differentiation optimizes each region's performance for its specific function.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If a clamping nut is tightly secured to hold the machining bar, then longitudinal positioning is achieved, but the bar requires very exact adjustment with the bore and cannot maintain position under cutting forces

Engineering Contradiction:
Improvelongitudinal positioning precisionVSAvoidrigidity under cutting forces
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The clamping mechanism is segmented into longitudinal support (rear stop with beveled face) and lateral support (second support zone with lateral surfaces). This segmentation allows the longitudinal positioning to be precise while the lateral support provides the rigidity needed to maintain position under cutting forces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention merges the longitudinal positioning function (rear stop) with the lateral positioning function (second support zone) into a unified support system. This combination ensures that both longitudinal precision and lateral rigidity are achieved simultaneously, allowing the bar to maintain its position under cutting forces.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If a deformable sleeve is used to transmit longitudinal force to the cutting bar, then the bar can be positioned, but precise radial positioning and maintenance of position under cutting forces cannot be guaranteed

Engineering Contradiction:
Improveassembly simplicityVSAvoidradial positioning precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The deformable sleeve is extracted from the support system and replaced with rigid lateral support surfaces in the second support zone. This extraction eliminates the radial play introduced by the sleeve while maintaining the simplicity of the clamping nut assembly, achieving both ease of operation and precise radial positioning.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The lateral support surfaces act as intermediaries between the clamping nut and the machining bar, providing precise radial positioning without requiring the deformable sleeve. These surfaces transmit the clamping force directly to the bar, ensuring both ease of assembly and precise positioning.

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

The system ensures accurate and rigid positioning of the machining bar, reducing vibrations and the need for strong tightening, while distributing holding forces effectively to maintain the bar's position during machining, enhancing overall machining precision and stability.

Implementation Method 1

a conical portion (28, 32) arranged to create, when the nut is tightened, two concurrent support forces with the first support force

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

distributing holding forces effectively to maintain the bar's position during machining

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3016768B1System for machining
Publication Date: 2019.12.11 APPLITEC MOUTIER
  • EP3016768B1 patent drawingFigure 1
  • EP3016768B1 patent drawingFigure 2a~2b
  • EP3016768B1 patent drawingFigure 3

AI summary

The invention relates to a machining system comprising a tool holder (10), a machining shaft (12) and a tightening nut (16). The tool holder (10) comprises a bore (14) extending in a longitudinal direction and into which the machining shaft (12) is to be inserted. The machining shaft comprises a cutting area (12a) having a cutting edge (13) for machining a workpiece when subjected to a cutting force F3 defining a cutting direction perpendicular to the longitudinal direction, and a holding area (12b) provided inside the tool holder (10), wherein the holding area comprises at the two ends thereof a first bearing area (22a) on the side opposite the cutting edge and a second bearing area (22b) on the cutting edge side. The tightening nut (16) comprises an opening (20) for the cutting edge (13) of the shaft (12) to pass through and is adapted such as to be tightened on the end of the tool holder (10) comprising the bore (14) and such as to engage with the machining shaft (12) at the second bearing area (22b). The machining system is arranged such that the tightening of the nut (16) on the tool holder (10) generates bearing forces F1, F2 respectively on the first (22a) and second (22b) bearing areas of the shaft (16), that position and retain the machining shaft relative to the tool holder (10) and at the first bearing area (22a) in the longitudinal direction and the cutting direction such that the bearing force F2 of the nut (16) on the shaft (12) at the second bearing area (22b) comprises a component parallel to the cutting direction in order to position and retain the shaft (16) relative to the tool holder (10) and at the second bearing area (22b) in the cutting direction.