Drum-Wall Tank Rib Forming Without Inner Mandrels

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Solution Overview

Problem

Existing methods for producing gas or liquid tanks with internal longitudinal ribs are inefficient, particularly when using inner mandrels that require reshaping the outer contour and are not economical for larger workpieces, and often involve cutting or complex setup.

Innovation Solution

A method using rotatably mounted profiling rollers to form an inner profile with longitudinal ribs on the inside of a drum-shaped peripheral wall without cutting, where the profiling roller rotates relative to the workpiece, allowing for synchronized rotation and deformation to create a precise inner profile, with optional counter-pressure rollers to maintain the outer shape.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If an inner mandrel with counter-profile is used to form the inner profile, then the inner profile can be formed, but the device complexity increases and it is not economical for larger workpieces

Engineering Contradiction:
Improveinner profile formationVSAvoidmandrel complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention uses a profiling roller that carries a profile which is a copy or replica of the desired inner profile. This profile on the roller is matched to the inner diameter of the workpiece, allowing the inner profile to be formed by rolling without requiring a complex inner mandrel with counter-profile. The profiled roller acts as a simplified copying tool that transfers the desired profile geometry directly onto the workpiece inner surface.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The profiling roller is a simpler, more economical tool compared to a complex inner mandrel. It can be easily manufactured, changed, and replaced when different profiles are needed. The roller serves as a disposable or replaceable forming element that does not require the permanent, complex infrastructure of a full mandrel system, making the process more economical especially for larger workpieces where mandrels would be prohibitively complex.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Manufacturing precision

If flow-forming is used to form longitudinal ribs, then the inner profile can be created, but the outer contour must be reshaped

Engineering Contradiction:
Improveinner profile with longitudinal ribsVSAvoidouter contour
Core Design Contradiction:
Manufacturing precisionVSShape

Solution Approach 1:

The profiling roller applies deformation locally only to the inner surface of the workpiece where the profile is required. The roller contacts only the inner circumference, forming the inner profile with longitudinal ribs through localized plastic deformation. This local action leaves the outer contour of the workpiece unchanged, as the forming force is concentrated at the inner surface contact zone between the roller and workpiece.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If the entire pipe wall is formed into the toothing, then the profile is formed both on the inside and outside, but the wall thickness is reduced throughout

Engineering Contradiction:
Improveprofile formationVSAvoidwall thickness
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The profiling roller forms the profile by deforming only the inner surface layer of the workpiece wall. The deformation is localized to the region where the roller contacts the inner surface, creating the inner profile without requiring formation of the entire pipe wall. This localized deformation minimizes material displacement and wall thickness reduction, as only the contacted portion undergoes significant plastic deformation.

Inventive Principle:
Principle #3Local quality

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

Enables efficient production of stable, thin-walled gas or liquid tanks with axial longitudinal ribs, maintaining the outer shape and allowing for larger diameters without the need for complex mandrels or cutting, resulting in a cost-effective and precise forming process.

Implementation Method 1

the material of the workpiece is deformed without cutting and the desired inner profile with the axial longitudinal ribs is formed

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

the profiling roller rotates relative to the inside of the peripheral wall, with the inside profile being formed without cutting

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3423209B1Method for manufacturing a gas or liquids tank having a drum-type peripheral wall
Publication Date: 2022.02.23 LEIFELD METAL SPINNING AG
  • EP3423209B1 patent drawingFigure 1

AI summary

The invention relates to a method for shaping a workpiece (1) having a drum-type peripheral wall (2), on the inner face (3) of which an inner profile (5) featuring longitudinal ribs (6) is formed by feeding at least one profiling roll (12) to said inner face (3). According to the invention, at least one rotatably mounted profiling roll (12) is fed to an inner face (3) of the peripheral wall (2) of the workpiece (1), and said at least one profiling roll (12) rotates relative to the inner face (3) of the peripheral wall (2) such that the inner profile (5) is formed in the inner face (3) in a non-cutting manner.