Thread-Cutting Device with Protective Element for Sewing Machines

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Solution Overview

Problem

Existing thread-cutting devices for sewing machines often leave long thread residues, which can damage the product surface and impair its visual or mechanical properties, and require complex manual reworking or specialized machines for shortening.

Innovation Solution

A method and device that uses a hinged protective element to cover the thread area during cutting, allowing precise positioning of the thread cutting device for minimal residual thread length, with automatic height adjustment and the option to cut threads of varying thickness, using a heating wire for thermal cutting to minimize surface damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional thread-cutting device is used, then the cutting operation is simple, but long thread residues remain that damage the product surface

Engineering Contradiction:
Improvethread residue lengthVSAvoidcutting device structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The cutting device is segmented into multiple functional components: a protective element that covers the product surface, a positioning element that defines the cutting location, and a cutting element that performs the actual cut. This segmentation allows each component to perform its specific function optimally, achieving precise thread residue control while maintaining manageable device complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A protective element is introduced as an intermediary component between the cutting device and the product surface. This protective element serves multiple functions: it protects the product surface from damage, provides a reference surface for positioning, and enables precise alignment of the cutting element. The intermediary element resolves the contradiction by adding controlled complexity that ultimately simplifies the overall cutting operation

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If the cutting device is positioned close to the product surface to minimize thread residues, then thread residue length is reduced, but the risk of mechanical damage to the product surface increases

Engineering Contradiction:
Improvethread residue lengthVSAvoidproduct surface damage risk
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The protective element is positioned beforehand to cover and protect the product surface before the cutting operation begins. This prior protection measures prevents any potential mechanical damage while allowing the cutting element to operate at the optimal position for minimizing thread residues. The cushioning effect is built into the device structure, ensuring surface protection is automatic and reliable

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The protective element acts as an intermediary barrier between the cutting element and the product surface. It allows the cutting element to be positioned close to the surface for precise cutting while simultaneously protecting the surface from mechanical damage. The intermediary element decouples the positioning requirement from the damage risk, resolving the technical contradiction

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If manual reworking or specialized machines are used to shorten thread residues, then thread residue length is reduced, but device complexity and production time increase

Engineering Contradiction:
Improvethread residue lengthVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The protective element, positioning element, and cutting element are merged into a single integrated cutting device that performs all functions in one operation. This eliminates the need for separate manual reworking steps or specialized post-processing machines. The combined device achieves precise thread residue control while maintaining high production efficiency, as the cutting operation is completed during the normal sewing cycle without additional processing steps

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

Ensures very short thread residues and maintains high surface quality of the sewn material, with increased operational reliability and reduced risk of mechanical damage, allowing for efficient and precise thread cutting independent of product thickness.

Implementation Method 1

using a heating wire for thermal cutting to minimize surface damage

Methodology Applied
Scientific EffectThermal cutting: Heating

Data Source

PatentEP1913190B1Method and apparatus for operating a thread-processing machine having a thread-cutting device
Publication Date: 2010.10.06 ECKER ANDREAS
  • EP1913190B1 patent drawingFigure 1~2
  • EP1913190B1 patent drawingFigure 3~4
  • EP1913190B1 patent drawingFigure 5~7

AI summary

The present invention relates to a method and an apparatus for operating a thread-processing machine having a thread-cutting device. In order to provide a method and a corresponding apparatus for operating a thread-processing machine having a thread-cutting device, which achieves improved results with increased operational reliability in comparison with known apparatuses and methods, it is proposed that the processed product (3) is covered with an articulated or flexible protective element to protect the surface of the sewn product in a region around a thread (2) which is to be severed only after the thread-processing operation is ended, and the thread-cutting device (4) is moved onto a cutting point and is positioned for cutting relative to the protective element.