Thread Forming Tool Displacement Section for Wood Composites

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Solution Overview

Problem

Existing tools for introducing internal threads into wooden elements with cylindrical recesses are inefficient for forming long thread sections with large diameters, leading to prolonged processing times and increased effort, especially when producing thick wood composites like wooden walls for house construction.

Innovation Solution

A tool with a displacement section featuring an external thread structure, allowing for the chip-free introduction of internal threads without cutting, which accommodates solid wood screws with low torque, using a combination of a displacement section with a triangular external thread and a post-forming section with a trapezoidal thread to displace and reshape wood material effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional cutting tools are used to form internal threads in wooden elements, then thread formation is possible, but processing time increases and material waste occurs

Engineering Contradiction:
Improveprocessing speedVSAvoidmaterial waste
Core Design Contradiction:
ProductivityVSLoss of substance

Solution Approach 1:

The patent replaces the conventional mechanical cutting system with a displacement-based forming system. The tool uses a displacement section with an external thread structure that displaces wood material plastically to form internal threads, eliminating the need for chip removal and significantly reducing processing time and material waste.

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

Solution Approach 2:

The patent changes the fundamental mechanism from cutting (removal) to displacement (forming). By using a displacement section with specific geometric parameters (external thread structure with controlled pitch and depth), the wood material is transformed into the desired thread shape without material loss, improving both productivity and reducing substance loss.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If long thread sections with large diameters are formed using existing tools, then thread formation is achieved, but machining time is prolonged

Engineering Contradiction:
Improvemachining speedVSAvoidmachining time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent replaces the conventional multi-pass cutting approach with a single-pass displacement forming process. The displacement section is designed to form long thread sections with large diameters in one continuous operation, eliminating the time-consuming multiple cutting passes required by conventional tools.

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

Solution Approach 2:

The tool incorporates a displacement section followed by a post-forming section. The displacement section preliminarily forms the thread shape by displacing material, and the post-forming section completes the thread formation with precise geometry. This preliminary action allows long thread sections to be formed efficiently without prolonged machining time.

Inventive Principle:
Principle #10Preliminary action

3Loss of substance

If chip-free thread formation is used, then material waste is reduced, but tool design complexity increases

Engineering Contradiction:
Improvematerial wasteVSAvoidtool structure
Core Design Contradiction:
Loss of substanceVSDevice complexity

Solution Approach 1:

The patent divides the tool into distinct functional sections: a displacement section with an external thread structure for chip-free material displacement, and a post-forming section for final thread geometry formation. This segmentation allows each section to perform its specific function efficiently, achieving chip-free formation without excessive overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses carefully controlled geometric parameters in the displacement section (external thread pitch, depth, and profile) to achieve chip-free material displacement. By optimizing these parameters, the tool forms threads without chips while maintaining a relatively simple structure, balancing material waste reduction with acceptable design complexity.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If friction is reduced during screwing, then torque requirement decreases, but tool design becomes more complex

Engineering Contradiction:
Improvescrewing effortVSAvoidtool design
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent segments the tool into a displacement section and a post-forming section. The displacement section creates a compressed, densified material structure that reduces friction during screwing, while the post-forming section ensures proper thread geometry. This segmentation achieves low friction and low torque requirements without requiring overly complex tool design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The displacement section uses specific geometric parameters (external thread profile, pitch, and depth ratios) to compress and densify the wood material during thread formation. This parameter optimization creates a material structure with reduced friction coefficients, lowering torque requirements during screwing while maintaining acceptable tool design complexity.

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

Enables the rapid production of thick wood composites with reduced material waste and effort, as the tool's design ensures low friction and efficient self-centering, allowing for the production of wooden walls with enhanced structural integrity and reduced material-related friction during screwing.

Implementation Method 1

a displacement section ( 14) with an external thread structure, which is designed to displace wood material in the wooden element(s)

Methodology Applied
Scientific EffectMaterial displacement: Deformation

Implementation Method 2

features a helical screw structure with inclined walls converging at acute angles

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP2407265B1Tool for forming an internal thread, method for producing a wood assembly with such a tool and wood assembly produced using such a method
Publication Date: 2020.01.08 ROMBACH ROLF
  • EP2407265B1 patent drawingFigure 1
  • EP2407265B1 patent drawingFigure 2
  • EP2407265B1 patent drawingFigure 3

AI summary

The tool comprises has a shank portion (13) for non-rotatable connection with a rotary drive. An external thread structure is formed by a displacement section (14) for displacement of wooden material in the wood elements. The external thread structure has two groove bottoms running diagonally towards each other. Independent claims are also included for the following: (1) a method for manufacturing a wooden composite; and (2) a wooden wall.