Thermoplastic Thread Fusion Device for Warp Knitting

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Solution Overview

Problem

Existing thread connecting devices for thermoplastic textile threads often result in large-diameter knots that can easily catch on textile tools, leading to breakage or damage, and existing methods lack stability and precision in connecting multiple threads simultaneously.

Innovation Solution

A thread connecting device with two pressure elements and an energy input device, where the pressure elements are driven transversely to pinch and fuse thermoplastic textile threads, using ultrasonic or thermal energy to create a stable, small-diameter connection point that minimizes catching and allows for simultaneous connection of multiple threads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a knotting device is used to connect two threads, then the threads can be connected together, but the resulting knot has a relatively large diameter that can easily get caught on textile tools

Engineering Contradiction:
Improvethread connection stabilityVSAvoidknot diameter
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The patent replaces the mechanical knotting system with a thermoplastic fusion system. Instead of creating a mechanical interlocking knot, the invention uses heat and pressure to melt and fuse the thread ends together, forming a smooth connection point that does not protrude and cannot catch on tools. This substitution of mechanical joining with thermal joining resolves the contradiction between connection reliability and knot size.

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

Solution Approach 2:

The invention changes the physical state of the thread material from solid to molten and back to solid through controlled heating and cooling. By heating the thread ends to the melting point of the thermoplastic material and then fusing them under pressure, the connection point forms with a diameter only slightly larger than the original thread, eliminating the large-diameter knot problem while maintaining connection strength.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If elastic yarns are connected by thermocompression using a special device, then the connection is stable, but the device structure becomes complex

Engineering Contradiction:
Improvethread connection stabilityVSAvoiddevice structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates multiple functions into a single knitting needle component. The needle serves both as the knitting tool and as the heating element for thermocompression. The needle can be heated to melt thermoplastic threads during the knitting process itself, eliminating the need for separate specialized connection devices. This multi-functionality reduces device complexity while maintaining reliable connections.

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

Solution Approach 2:

The invention merges the knitting function and the thread connection function into a single integrated process. The heating element is incorporated directly into the knitting needle, allowing the needle to both knit the fabric and simultaneously fuse thermoplastic threads at the desired locations. This consolidation of functions simplifies the overall device structure compared to using separate specialized connection devices.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If a heating element is guided along the yarns to join them by heat, then the connection is achieved, but the process time increases

Engineering Contradiction:
Improvethread connection stabilityVSAvoidconnection process time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent enables continuous thread connection during the knitting process itself. The heating element is integrated into the knitting needle, allowing threads to be fused continuously as they are being knitted, rather than requiring separate intermittent connection steps. This continuous action eliminates idle time and integrates the connection process into the main production flow, significantly reducing total process time.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The invention incorporates the heating and fusion function into the knitting needle before the knitting process begins. The needle is pre-heated or equipped with heating capability, so that when threads are fed through the needle during knitting, they are immediately fused without requiring additional heating time. This preliminary preparation of the heating element enables simultaneous knitting and connection, reducing overall process time.

Inventive Principle:
Principle #10Preliminary action

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 device achieves a stable and precise connection with a diameter only slightly larger than the threads, reducing the risk of catching and enabling efficient processing of multiple threads without the formation of large knots or shoulders, ensuring a homogeneous and stable connection.

Implementation Method 1

The energy input device is preferably an ultrasonic generator. The ultrasonic generator generates ultrasonic waves, which set the textile threads into high-frequency vibrations. This creates internal friction in the textile threads, which in turn heats up the textile threads.

Methodology Applied
Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

This creates internal friction in the textile threads, which in turn heats up the textile threads. The textile threads are heated up so much that they melt.

Methodology Applied
Scientific EffectInternal friction heating: Viscous Heating

Implementation Method 3

The thermal energy generated by the heating element can be conducted to the thermoplastic textile threads by convection, thermal conduction and/or thermal radiation.

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

The thermal energy generated by the heating element can be conducted to the thermoplastic textile threads by convection, thermal conduction and/or thermal radiation.

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 5

Thermoplastic materials melt when heated. The energy input device supplies energy to the textile threads so that they can heat up and fuse together.

Methodology Applied
Scientific EffectThermoplastic melting and fusing: Melting

Data Source

PatentEP3798341B1Thread connecting device and warp knitting machine comprising a thread connecting device
Publication Date: 2022.08.24 KARL MAYER STOLL R&D GMBH
  • EP3798341B1 patent drawingFigure 1~3
  • EP3798341B1 patent drawingFigure 4~6

AI summary

The invention relates to a thread joining device (1) for joining a first thermoplastic textile thread (7) to a second thermoplastic textile thread (8). According to the invention, the thread joining device (1) comprises a pressure device (3) for exerting a mechanical pressure on a thread pair formed by the first thermoplastic textile thread (7) and the second thermoplastic textile thread (8), and an energy input device (4) for welding the thread pair while the thread pair is arranged in the pressure device (3). The invention further relates to a warp knitting machine with the thread joining device (1) according to the invention.