Electric Cutter Spindle Radial Support for High Cutting Force

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Solution Overview

Problem

Existing electric scissors are limited in their ability to apply sufficient cutting force, especially when cutting thicker materials, as the radial forces on the spindle are kept low to prevent bending, resulting in an uneven distribution of force across the opening area of the knives.

Innovation Solution

The threaded spindle is mounted radially immovably in its front region with bearings, allowing for increased radial forces to be absorbed, and the threaded nut is mounted radially immovable and axially displaceable, ensuring the spindle is free of radial forces, enabling a greater cutting force with increasing opening angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the radial forces on the spindle are kept low to prevent bending, then the spindle stability is improved, but the cutting force that can be exerted on thicker materials is reduced

Engineering Contradiction:
Improvespindle stabilityVSAvoidcutting force
Core Design Contradiction:
Stability of the object's compositionVSForce

Solution Approach 1:

The bearing support is segmented into two distinct locations: one bearing supports the threaded nut at the rear region of the spindle, and another bearing supports the front region of the spindle. This segmentation allows different parts of the spindle to be supported independently, enabling the front region to handle high radial forces while the overall spindle remains stable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The support system is extended from a single-point support to a distributed support system along the spindle axis. By adding bearing support at both the front and rear regions, the system transforms from one-dimensional point support to two-dimensional distributed support, allowing the spindle to withstand higher forces without bending.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Force

If the link moves only slightly out of the axis of the gear spindle, then the radial forces on the spindle are minimized, but the cutting force increases with opening angle is limited

Engineering Contradiction:
Improvecutting forceVSAvoidspindle stability
Core Design Contradiction:
ForceVSStability of the object's composition

Solution Approach 1:

The threaded nut acts as an intermediary element between the link and the spindle. The link moves the threaded nut axially along the spindle, and the threaded nut in turn applies force to the movable knife. This intermediary mechanism allows the link to remain close to the spindle axis while still achieving effective force transmission and increased cutting force with opening angle.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Force

If a bearing is added to support the front region of the spindle, then the cutting force capability is improved, but the device complexity increases

Engineering Contradiction:
Improvecutting forceVSAvoiddevice complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The additional bearing at the front region of the spindle serves multiple functions: it supports the spindle against radial forces, maintains spindle alignment, and enables the linkage geometry to be optimized for increased cutting force. By making this single component multi-functional, the increase in device complexity is minimized while achieving multiple benefits.

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

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

This design allows for a significant increase in cutting force with larger opening angles, preventing spindle bending and enabling effective cutting of thicker materials while maintaining stability, with angles greater than 30° providing sufficient force for most applications and higher angles achieving even higher forces.

Implementation Method 1

the threaded spindle is mounted in a radially immovable manner in its front region facing away from the motor by means of at least one bearing

Methodology Applied
Scientific EffectBall bearing: Ball Bearing

Implementation Method 2

which has a ball screw and a ball screw nut, the ball screw being connected to the output shaft of an electric geared motor

Methodology Applied
Scientific EffectBall screw: Screw

Data Source

PatentEP2266388B1Electric cutter
Publication Date: 2012.02.15 LUNATONE INDUSTRIELLE ELEKTRONIK GMBH
  • EP2266388B1 patent drawingFigure 1
  • EP2266388B1 patent drawingFigure 2
  • EP2266388B1 patent drawingFigure 3

AI summary

The cutter has a fixed knife (101) and a movable knife (102) that is pivotably supported around a rotational axis (7). A threaded spindle (4) is driven by an electric motor (104) and supported in an axial direction such that the spindle is only rotatable. A threaded nut (6) is seated on the spindle and torque-proofly supported with respect to the spindle. The nut is moved in the axial direction during rotation of the spindle. A connecting rod (2) connects the nut with the movable knife. The spindle is radially immovably supported in its front area turned away from the motor by a bearing (10).