Envelope Cutting Device With Inclined Rotary Support

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing mechanical letter openers with offset cutting knives often result in incomplete cuts due to speed discrepancies between transport rollers and knives, leading to shreds and manufacturing tolerance issues, causing envelopes to move away from the cutting path.

Innovation Solution

A rotary cutting device with a support element inclined at an angle α (1-5°) ensures constant envelope contact during movement, using a pressing element and elastic return mechanism to maintain position and prevent shredding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If offset cutting knives are used in mechanical letter openers, then the cutting action can be achieved, but incomplete cuts occur due to speed discrepancies between transport rollers and knives

Engineering Contradiction:

Improvecutting completenessVSAvoidspeed discrepancy between transport rollers and knives

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

Instead of making the support element rotate (which would complicate the drive mechanism), the patent inverts the approach by making the knife rotate while the support element remains stationary. This simplifies the drive system while still achieving the necessary speed synchronization between the cutting element and transport surface.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the geometric parameter of the support element by inclining it at a specific angle (1-5 degrees) relative to the transport surface. This angular parameter adjustment allows the envelope to maintain constant contact with the transport surface during cutting, compensating for speed discrepancies between the knife and transport rollers.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If conventional cutting knives are used, then cutting action is achieved, but envelopes move away from the cutting path due to manufacturing tolerances

Engineering Contradiction:

Improvecutting position accuracyVSAvoidenvelope position stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent introduces a specific geometric parameter - the inclination angle of the support element (1-5 degrees). This angular parameter compensates for manufacturing tolerances in the knife and roller diameters by ensuring the envelope maintains constant contact with the transport surface throughout the cutting process, preventing the envelope from moving away from the cutting path.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The inclined support element creates a condition where the envelope remains in constant contact with the transport surface during cutting, effectively creating an equipotential contact condition that eliminates position instability caused by manufacturing variations in knife and roller dimensions.

Inventive Principle:

Principle #12Equipotentiality

3Ease of manufacture

If two offset cutting knives are used, then cutting can be performed, but shreds of paper are generated

Engineering Contradiction:

Improvecutting device simplicityVSAvoidpaper shreds

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent extracts one of the two cutting knives from the conventional offset knife arrangement, using only a single rotating knife. The inclined support element replaces the need for the second knife, simplifying the device structure while preventing the envelope from being completely cut and shredded by maintaining controlled contact during the cutting process.

Inventive Principle:

Principle #2Taking out (Extraction)

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 solution enables complete, parallel cutting of envelopes over their entire length without shredding, independent of manufacturing tolerances, ensuring consistent and reliable operation.

Implementation Method 1

whose axis of rotation forms with a drive axis of said rotary knife a predetermined angle of inclination α

Methodology Applied

Scientific EffectGeometric inclination:

Implementation Method 2

said support is movable along said cutting axis against an elastic return element

Methodology Applied

Scientific EffectMechanical force: Mechanical Force

Implementation Method 3

said support is movable along said cutting axis against an elastic return element

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP2465702B1Device for cutting envelopes

Publication Date: 2015.03.25 NEOPOST TECHNOLOGIES SA

Figure 1
Figure 2~3
Figure 4A~4B

AI summary

Envelope cutting device comprising a rotating knife (34) capable of cutting an envelope and a rotating support element (40) against which this envelope is in contact when passing in front of the rotating knife and of which an axis of rotation forms with a drive axis of the rotating knife a predetermined angle of inclination α.