Extrusion Mandrel Transition Support for Pipe Wall Thickness Control
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Solution Overview
Problem
Existing metal pipe extrusion processes with mandrels having axially offset pressing surfaces of different radial characteristics result in constrictions and uneven wall thicknesses, leading to negative influences such as guide inaccuracies and load peaks in the extruded metal pipes.
Innovation Solution
A mandrel with axially offset pressing surfaces and a support surface in the transition region, allowing for controlled adjustment of the constriction depth and length, and wall thickness variations to minimize the negative effects of constrictions by ensuring proper material displacement and flow during the extrusion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mandrel with axially offset pressing surfaces of different radial characteristics is used to change wall thickness, then the inner diameter can be changed to complement the pressing surfaces, but a constriction with significant depth occurs in the transition area
Solution Approach 1:
The mandrel is preliminarily positioned in the first pressing position during the extrusion process to provide support before the transition to the second pressing position. This preliminary positioning prevents excessive material flow and constriction formation in the transition area, allowing wall thickness change while minimizing harmful constrictions.
Solution Approach 2:
The mandrel's radial characteristics are changed by axially offsetting the pressing surfaces and repositioning the mandrel between first and second pressing positions. This parameter change enables wall thickness variation while the controlled repositioning minimizes constriction depth in the transition region.
2Manufacturing precision
If the mandrel is repositioned from the first pressing position to the second position to change wall thickness, then the inner diameter changes accordingly, but the length of the constriction increases leading to guide inaccuracies and load peaks
Solution Approach 1:
The mandrel provides preliminary support in the transition area during repositioning, which stabilizes the workpiece and prevents excessive constriction length. This preliminary action ensures that the transition between different wall thicknesses occurs smoothly without creating long constrictions that would cause guide inaccuracies or load peaks.
3Object-affected harmful factors
If the constriction depth is reduced through mandrel support, then the negative effects are minimized, but the transition area becomes more complex to control
Solution Approach 1:
The mandrel is designed with dynamic repositioning capability between first and second pressing positions. This dynamic adjustment allows the mandrel to adapt its position during the extrusion process, providing support exactly where needed in the transition area to minimize constriction effects while maintaining controllable and manageable device complexity.
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 effectively reduces the depth and length of constrictions, minimizing their adverse effects on the metal pipes, while allowing for precise control over wall thickness variations, thereby improving the quality and reducing material consumption.
Implementation Method 1
a metal block is pressed through a die and over a mandrel to form a metal pipe
Data Source
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AI summary
If a mandrel (6) for extruding metal pipes, having two axially offset pressing surfaces (63; 64) with different radial embossing and having a transition region (66) between these two pressing surfaces (63; 64) has a support surface (62) in the transition region (66) then the negative effect of narrowing, which arises owing to the mandrel (6) shifting from a first pressing position, in which the first (63) of the two pressing surfaces interacts with a die, to a second pressing position, in which the second pressing surface (64) interacts with the die, can be minimised.