Concave Shear Edges for Tube Cutting Without Wire Damage

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Solution Overview

Problem

Current tools for cutting corrugated tubes with wires are inefficient and prone to damaging the outer insulating layer or cutting the wires, often requiring two-handed operation and complex maneuvers.

Innovation Solution

A pair of shears with pivotally connected concave-shaped tube cutting edges that allow single-handed operation, preventing wire damage by locking the tube in place and distributing pressure evenly, and featuring beveled sections for efficient cutting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional tools (nippers, cable knife, tube cutter) are used to cut corrugated tubes, then cutting can be performed, but the tools require complex maneuvers and increase the risk of damaging wires or insulating layers

Engineering Contradiction:
Improverisk of damaging wiresVSAvoidcomplex maneuvers
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The cutting tool is segmented into distinct functional zones: corrugated tube gripping portions with indexing means, smooth tube gripping portions, and cutting blade portions. This segmentation allows each zone to perform its specific function optimally while reducing overall operational complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The indexing means on the gripping portions automatically engage with the corrugations of the tube, self-aligning the cutting blade without requiring complex manual positioning maneuvers by the operator

Inventive Principle:
Principle #25Self-service

2Productivity

If pre-fit corrugated tubes with electrical wiring are used, then efficiency and ease of use are improved, but the risk of damaging the outer insulating layer or cutting wires increases

Engineering Contradiction:
Improveefficiency of pre-fit tubesVSAvoiddamage to insulating layer
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The cutting blade portions have varying geometries and sharpness characteristics tailored to specific cutting needs: some blades are sharper for penetrating corrugated walls, while others have controlled geometry to stop before reaching wires. The gripping portions have localized indexing features that precisely position the blade relative to the tube wall thickness

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The indexing means engage with tube corrugations before cutting begins, pre-positioning the blade at a safe distance from the wires. This preliminary positioning prevents the blade from penetrating too deep and damaging the insulating layer or cutting wires

Inventive Principle:
Principle #9Preliminary anti-action

3Reliability

If two-handed operation with rotational maneuver is required, then cutting can be performed, but the ease of operation decreases and limits application scenarios

Engineering Contradiction:
Improvecutting accuracyVSAvoidsingle-handed operation capability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The gripping portions and cutting blade portions are merged into a single integrated tool body, allowing the operator to perform both gripping and cutting functions with one hand. The indexing means and cutting blade work together as a unified system without requiring separate manual operations

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Instead of requiring the operator to rotate the tool around the tube, the indexing means are designed to engage the tube corrugations and automatically position the blade, inverting the traditional operational sequence and eliminating the need for rotational maneuvers

Inventive Principle:
Principle #13The other way round (Inversion)

Data Source

PatentEP3018778B1Pair of shears for cutting tubes
Publication Date: 2019.08.21 KLINKERS MARCUS LEONARDUS HENDRICKUS HUBERTUS
  • EP3018778B1 patent drawingFigure 1~3
  • EP3018778B1 patent drawingFigure 4~6
  • EP3018778B1 patent drawingFigure 7~8

AI summary

The present invention generally relates to a pair of shears (1) that is suitable to be used for cutting tubes, in particular tubes containing one or more wires, as the pair of shears (1) is adapted to prevent an outer insulating layer of the wires from getting damaged, or to prevent the wires from being cut along with the tubes. To this end, the pair of shears (1) comprises two shears (2a, 2b), wherein cooperating tube cutting edges (12, 13) have a concave shape, and wherein, in a closed position of the pair of shears (1), in which the tube cutting edges (12, 13) have been moved towards each other to a maximum extent, the shearing portions (11) of the shears (2a, 2b) partially overlap and a space (26, 27) having a convexly curved periphery is delimited by the tube cutting edges (12, 13).