Knife Sharpening Device With Crossed Linear Rods

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Solution Overview

Problem

Existing knife grinding devices often fail to achieve a consistently sharp and smooth cutting edge due to variable grinding angles and limited contact area, leading to coarse and irregular edges, especially when using crossed wet rods with rotating attachments.

Innovation Solution

A knife grinding device with crossed wet rods arranged in an X-shape on a horizontal base plate, where each rod is attached to a sled guide for linear movement, maintaining a constant crossing angle and allowing for even sharpening by sliding past each other, with a tensile spring for automatic reset and interchangeable grinding steels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If crossed honing rods are rotatably mounted to allow the knife to be drawn through, then the sharpening effectiveness is improved, but the sharpening angle becomes variable and the rods wear down in a linear fashion over a small area

Engineering Contradiction:
Improvesharpening effectivenessVSAvoidsharpening angle consistency
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies the dynamics principle by making the honing rods linearly displaceable along guide rails rather than rotatably mounted. The rods can move horizontally along their respective guide rails, allowing dynamic adjustment of their positions while maintaining a constant crossing angle. This dynamic linear movement replaces the static rotational mounting, enabling the knife to be drawn through the crossed rods while preserving angle consistency and distributing wear across the entire rod surface.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If the honing rods are fixed in position, then the sharpening angle remains constant, but the contact area with the knife is limited and wear is concentrated on a small area

Engineering Contradiction:
Improvesharpening angle consistencyVSAvoidcontact area
Core Design Contradiction:
Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The patent transforms the fixed position of honing rods into a dynamic linearly displaceable configuration. Each rod can move horizontally along its guide rail, enabling the contact area with the knife to be dynamically adjusted and expanded during the sharpening process. This dynamic movement allows the entire surface of each rod to come into contact with the knife edge, significantly increasing the effective contact area while maintaining constant sharpening angles through the constrained linear motion paths.

Inventive Principle:
Principle #15Dynamics

3Area of stationary object

If the honing rods are made long to increase contact area, then the sharpening coverage is improved, but the device complexity and space requirements increase

Engineering Contradiction:
Improvecontact areaVSAvoiddevice structure
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent employs dynamic linear displacement of honing rods along guide rails to maximize contact area without requiring excessively long rods. By allowing the rods to move horizontally along their respective guide rails, the effective contact area is increased through the range of motion rather than through increased rod length. This dynamic approach maintains a compact device structure while achieving comprehensive sharpening coverage.

Inventive Principle:
Principle #15Dynamics

4Ease of operation

If manual pressure is applied to move the rods during sharpening, then the sharpening process is simple, but the operation requires two hands and reduces safety

Engineering Contradiction:
Improvesharpening process simplicityVSAvoidhand cut risk
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies the self-service principle by incorporating a spring mechanism that automatically moves the first honing rod unit back to its initial position after the knife has been drawn through. The spring is pre-tensioned and exerts a restoring force that displaces the rod unit horizontally along the guide rail, returning it to the starting position without requiring manual intervention. This self-service mechanism reduces the risk of hand cuts by eliminating the need for the user to manually reposition the rods.

Inventive Principle:
Principle #25Self-service

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 ensures a consistently sharp and smooth cutting edge with a constant grinding angle, minimizing the area not ground on both sides, and allows for easy manual operation with improved safety and effectiveness.

Implementation Method 1

a spring (2) which applies a spring tension in the direction of movement (R2) and thus displaces the first sharpening rod unit (6) against the direction of deflection along the horizontal direction (R1, R2)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

at least one slide (5) which interacts in a sliding manner with the first guide rail (3) is provided on the base (13') of the first holding device (15')

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3415271B1Knife sharpening device
Publication Date: 2022.08.17 LUBER JOSEF
  • EP3415271B1 patent drawingFigure 1
  • EP3415271B1 patent drawingFigure 2
  • EP3415271B1 patent drawingFigure 3

AI summary

A knife sharpening device 10 is described, comprising a horizontal base plate 1, at least one first sharpening rod unit 6 arranged on a top surface 1.1 of the base plate 1 with at least one first sharpening rod 11 extending along a first sharpening axis WA1, and at least one second sharpening rod unit 9 arranged on the top surface 1.1 of the base plate 1 with at least one second sharpening rod 12 extending along a second sharpening axis WA2. The first and second sharpening rods 11, 12 are oriented in a crossed orientation relative to each other and intersect at a point X. At least the first sharpening rod unit 6 is slidably mounted on the horizontal base plate 1 and is therefore linearly displaceable in a horizontal direction of movement R1, R2.