Symmetrical Scissor Elements for Thread Cutting Wear

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Solution Overview

Problem

Existing thread connecting devices have scissor elements with single cutting edges that wear out quickly, leading to short service lives and frequent replacements, which can cause workstation downtime if not immediately addressed.

Innovation Solution

Designing scissor elements with two symmetrical cutting edges, allowing for extended use by repositioning them at 180 degrees when one edge becomes worn or damaged, and using materials like ceramic or steel for enhanced durability and cost-effectiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If scissor elements are designed with single cutting edges, then the structure is simple and easy to manufacture, but the service life is short due to rapid wear

Engineering Contradiction:
Improveservice life of scissor elementsVSAvoidstructure of scissor elements
Core Design Contradiction:
Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The scissor element is segmented into two symmetrical cutting edges instead of a single cutting edge. Each scissor element now has a first cutting edge and a second cutting edge that are symmetrical to each other, allowing the element to be used twice as long by switching between edges when one becomes worn.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies asymmetry in reverse by creating symmetry - the two cutting edges are designed to be symmetrical to each other. This symmetrical design allows the scissor element to maintain identical cutting performance on both edges, enabling seamless switching when one edge wears down, thereby doubling the service life.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If scissor elements are replaced frequently due to wear, then cutting precision is maintained, but workstation downtime increases

Engineering Contradiction:
Improvecutting performanceVSAvoidworkstation downtime
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The scissor element is pre-designed with two symmetrical cutting edges during manufacturing. This preliminary action ensures that when one cutting edge becomes worn, the second cutting edge is already prepared and ready for immediate use, eliminating the need for frequent replacements and reducing workstation downtime.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of discarding the entire scissor element when one cutting edge wears out, the patent allows recovery and continued use of the scissor element by switching to the second cutting edge. This extends the usable life of each scissor element significantly, reducing waste and replacement frequency.

Inventive Principle:
Principle #34Discarding and recovering

3Duration of action of stationary object

If scissor elements are made more durable with symmetric design, then service life is extended, but manufacturing complexity increases

Engineering Contradiction:
Improveservice life of scissor elementsVSAvoidmanufacturing of scissor elements
Core Design Contradiction:
Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

The scissor element is designed with multi-functionality by incorporating two symmetrical cutting edges. This universal design allows the same scissor element to perform the cutting function twice, effectively doubling its service life without requiring fundamentally different manufacturing processes, as the symmetry can be achieved through standard machining techniques.

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

Data Source

PatentEP4470958A1Scissors for a thread cutting device
Publication Date: 2024.12.04 RIETER AUTOMATIC WINDER GMBH
  • EP4470958A1 patent drawingFigure 1
  • EP4470958A1 patent drawingFigure 2
  • EP4470958A1 patent drawingFigure 3~4

AI summary

The invention relates to shear elements 46 for a thread cutting device 41 of a thread joining device 19 for knot-free joining of two thread ends, with one thread cutting device 41 each above and below a splice channel 29 of the thread joining device 19, each comprising two shear elements 46, each having a cutting edge 47, 48 and which are movably mounted relative to each other for cutting the thread ends to length. According to the invention, at least one shear element 46 is designed to form two symmetrical cutting edges 47, 48, and both cutting edges 47, 48 of a shear element 46 are suitable for cutting the thread to length.