Eccentric Pipe Cutting Drive With Variable Stroke for Wall Integrity
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Solution Overview
Problem
Existing pipe cutting machines cause deformations in the pipe wall due to sequential vertical and horizontal stroke movements, which result in inadequate cutting of the tangentially aligned pipe wall during the first stroke, leading to subsequent deformation and cutting in the second stroke.
Innovation Solution
A cutting device with a hole-type cutting die that performs circular movements driven by a drive lever, allowing for a spiral or helical movement through the superimposition of circular and stroke changes, utilizing an eccentrically arranged crank pin drive and motors to vary the stroke continuously, thereby minimizing pipe wall deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sequential vertical and horizontal stroke movements are used to cut the pipe, then the cutting die can sever the pipe section, but the pipe wall lying tangentially relative to the direction of movement is not cut with the first stroke and is merely deformed, causing disadvantageous deformations in the deflected pipe sections
Solution Approach 1:
The patent applies curved/spiral motion instead of straight linear strokes. The cutting die performs a spiral cutting path around the pipe, following the cylindrical geometry of the workpiece. This curved motion allows the cutting edge to continuously engage the pipe wall tangentially, eliminating the deformation issue caused by perpendicular linear strokes while maintaining efficient cutting progression.
Solution Approach 2:
The invention transitions from two sequential linear strokes (vertical then horizontal) to a three-dimensional spiral motion. By adding the rotational dimension around the pipe axis, the cutting die achieves continuous engagement with the pipe wall in all tangential directions simultaneously, resolving the problem of incomplete cutting and deformation that occurred with sequential linear movements.
2Productivity
If two actuating drives acting perpendicularly are used to drive the cutting die, then the pipe section can be severed, but the device complexity increases due to the need for two independent drives and their coordination
Solution Approach 1:
The patent merges two separate actuating drives into a single drive mechanism. The eccentric crank mechanism converts one rotational motion into the required complex cutting path, combining the functions of what would otherwise require two independent drives. This reduces mechanical complexity while maintaining the ability to perform the complete cutting operation.
Solution Approach 2:
The single actuating drive with eccentric crank mechanism performs multiple functions simultaneously: it provides the cutting motion, controls the stroke length, and adjusts the cutting depth. This multi-functional mechanism replaces what would otherwise require separate dedicated drives for each motion component, simplifying the overall system architecture.
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 precise cutting of pipe sections with reduced deformation by allowing continuous variation of the cutting die's stroke, ensuring efficient and accurate cutting without the need for a cutting mandrel in most cases, while maintaining the integrity of the pipe wall.
Implementation Method 1
The cutting device comprises an eccentrically shaped bearing in an outer shaft, in which bearing an eccentrically shaped crank pin drive is supported so as to be movable relative to the outer shaft. A relative rotation of the crank pin drive and the outer shaft change the stroke.
Data Source
AI summary
A pipe cutting machine, which includes a hole-type movable cutting die (6b), which is driven by a drive lever (7), by means of which circular movements with a continuously variable stroke (h) can be performed, an eccentrically shaped crank pin bearing (26) in an outer shaft (18), in which a crank pin (11), which is arranged eccentrically on a crank pin drive (23), is movably supported in relation to the outer shaft (18), the crank pin (11) being in operative connection with the drive lever (7).