Pipe Cutting Device Eccentric Inner Blade Mechanism

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Solution Overview

Problem

Existing tube cutting apparatuses for thin-wall tubes with small diameters face challenges in cutting efficiency and complexity, particularly when using planetary gear mechanisms, which result in prolonged cutting times and complications in design and operation.

Innovation Solution

A tube cutting apparatus featuring a disc-shaped inner blade decentered from the main axis, supported by an eccentric shaft, and a simplified rotation transmission system using a main shaft and offset shaft coupling, allowing the inner blade to rotate and move radially while cutting the tube's circumference without a complex mechanism inside the tube.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a planetary gear mechanism is used to rotate the inner blade during cutting, then the inner blade can be rotated and moved radially, but the cutting time is prolonged and the structure becomes complicated

Engineering Contradiction:
Improveinner blade rotation and radial movementVSAvoidcutting time
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The invention extracts the complex planetary gear mechanism from the tube cutting apparatus and replaces it with a simple rotating support structure. The inner blade is directly mounted on a support that rotates with the tube, eliminating the need for additional gear mechanisms while maintaining the cutting function.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The support structure for the inner blade serves multiple functions: it holds the inner blade, rotates with the tube to enable circumferential cutting, and positions the inner blade radially. This multi-functional design replaces the specialized planetary gear mechanism.

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

2Ease of operation

If a planetary gear mechanism is used to rotate the inner blade during cutting, then the inner blade can be rotated and moved radially, but the device structure becomes complicated

Engineering Contradiction:
Improveinner blade rotation and radial movementVSAvoidmechanism structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The invention removes the planetary gear mechanism entirely and replaces it with a simple rotating support structure where the inner blade is directly mounted on a support that rotates with the tube, dramatically simplifying the device structure.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using a complex mechanism to rotate the inner blade relative to the tube, the invention inverts the approach by rotating the entire support structure with the tube, allowing the inner blade to cut along the circumference through the natural rotation.

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

3Ease of operation

If the inner blade is moved radially by a complex mechanism inside the tube, then the cutting function is achieved, but the apparatus cannot be used for small diameter tubes

Engineering Contradiction:
Improveinner blade radial movementVSAvoidapplicability to small diameter tubes
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The invention extracts the complex radial movement mechanism from inside the tube and replaces it with a simple rotating support structure that accommodates the inner blade, enabling the apparatus to cut tubes with small diameters of about 100 mm or less.

Inventive Principle:
Principle #2Taking out (Extraction)

4Speed

If the planetary gear rotates at high angular velocity, then the inner blade rotates faster, but the cutting time is prolonged due to multiple revolutions required

Engineering Contradiction:
Improveinner blade rotation speedVSAvoidcutting time
Core Design Contradiction:
SpeedVSProductivity

Solution Approach 1:

The invention ensures continuous cutting action by rotating the inner blade support structure continuously with the tube, allowing the inner blade to cut along the entire circumference in a single continuous motion without requiring multiple discrete revolutions.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP2415545B1Pipe cutting device and pipe cutting method
Publication Date: 2016.07.20 FUJI MACHINE WORKS
  • EP2415545B1 patent drawingFigure 1
  • EP2415545B1 patent drawingFigure 2
  • EP2415545B1 patent drawingFigure 3A~3P

AI summary

A pipe cutting device (100) is provided with a main shaft (1), an eccentric shaft (2), an inner cutting blade (3), outer cutting blades (4,5), a jaw coupling (7), a first transmission gear train (9), a second transmission gear train (10), and a motor (50). The rotation of the motor (50) is supplied to the main shaft (1) through the first transmission gear train (9) and is supplied to the eccentric shaft (2) at 3/4 the rotational speed of the main shaft (1) through both the second transmission gear train (10) and the jaw coupling (7). The eccentric shaft (30) moves on a circle which is eccentric by a predetermined distance (L), and the drive by the motor (50) causes the inner cutting blade (3) to move in the same direction as the eccentric shaft (30) on a circle which is eccentric by another predetermined distance (L) from the eccentric shaft (30). The inner cutting blade (3) rotates and moves while exposing a part of the peripheral surface thereof to the outside of a pipe (W) at multiple positions on the outer peripheral surface of the pipe (W).