Metal Pipe Expansion Electrode Constraint for Uniform Forming

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Solution Overview

Problem

In existing forming apparatuses, metal pipe materials do not expand evenly due to differences in engagement and frictional forces between electrodes, leading to inconsistent expansion forms and process errors.

Innovation Solution

A forming apparatus with a movement restriction mechanism on at least one electrode to control the expansion of the metal pipe material, using a protrusion portion or varying frictional forces to ensure consistent expansion direction and prevent excessive movement, aided by a control unit for precise temperature control and movement adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If electrodes on both sides hold the metal pipe material with substantially the same engagement force and frictional force, then the heating process is simple and symmetric, but the metal pipe material does not extend evenly from the electrodes and the form of expansion changes inconsistently

Engineering Contradiction:
Improveuniformity of expansion formVSAvoidcomplexity of electrode control system
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by making the engagement forces and frictional forces of the first and second electrodes different from each other. Specifically, the first electrode engages the metal pipe material with a first engagement force and generates a first frictional force, while the second electrode engages with a second engagement force and generates a second frictional force, where these values are deliberately made unequal to control the expansion direction and achieve uniform expansion form.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent applies local quality by creating different engagement conditions at different locations (electrodes) along the metal pipe material. Each electrode is configured with specific engagement forces and frictional forces tailored to its position, allowing localized control over the expansion behavior of the metal pipe material at each end.

Inventive Principle:
Principle #3Local quality

2Productivity

If the metal pipe material is heated by holding both end portions with electrodes and energizing each electrode, then the heating process is efficient and direct, but slight differences in engagement force and frictional force cause inconsistent expansion forms and process errors

Engineering Contradiction:
Improveheating efficiencyVSAvoidconsistency of expansion form
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent resolves this contradiction by deliberately creating asymmetric engagement conditions at the two electrodes. By setting different engagement forces and frictional forces at each electrode, the system maintains efficient direct heating while controlling the expansion to occur uniformly in a consistent direction, eliminating the inconsistency caused by equal engagement forces.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent applies parameter changes by modifying the engagement force and frictional force parameters at each electrode. By adjusting these parameters to be different between the first and second electrodes, the system maintains high heating efficiency while achieving consistent expansion form, thus resolving the contradiction between productivity and manufacturing precision.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If a movement restriction mechanism is provided on at least one electrode to restrict metal pipe material movement, then the expansion form is controlled consistently, but the device structure becomes more complex

Engineering Contradiction:
Improvecontrol of expansion formVSAvoidstructure of electrode system
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The movement restriction mechanism creates asymmetric constraints on the metal pipe material at the two electrodes. By restricting movement at one electrode while allowing or differently restricting movement at the other electrode, the system achieves consistent expansion form control. This asymmetric constraint mechanism is integrated into the electrode structure itself, providing precision control without requiring separate complex control systems.

Inventive Principle:
Principle #4Asymmetry

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 apparatus achieves controlled and consistent expansion of metal pipe materials, reducing process errors and ensuring uniformity in the formed products by restricting movement and adjusting forces, thereby improving the accuracy and reliability of the forming process.

Implementation Method 1

a first electrode and a second electrode which clamp the metal pipe material at both end sides and heat the metal pipe material by causing an electric current to flow through the metal pipe material

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a first fluid supply unit and a second fluid supply unit which supply a fluid into the metal pipe material heated by the first electrode and the second electrode to expand the metal pipe material

Methodology Applied
Scientific EffectGas pressure expansion: Pressure Increase

Data Source

PatentEP3603837B1Molding device
Publication Date: 2024.12.18 SUMITOMO HEAVY IND LTD
  • EP3603837B1 patent drawingFigure 1
  • EP3603837B1 patent drawingFigure 2A~2C
  • EP3603837B1 patent drawingFigure 3A~3B

AI summary

A forming apparatus is a forming apparatus which forms a metal pipe by expanding a metal pipe material, and includes: a forming die for forming the metal pipe; a first electrode and a second electrode which clamp the metal pipe material at both end sides and heat the metal pipe material by causing an electric current to flow through the metal pipe material; and a first fluid supply unit and a second fluid supply unit which supply a fluid into the metal pipe material heated by the first electrode and the second electrode to expand the metal pipe material, in which at least one of the first electrode and the second electrode is provided with a movement restriction mechanism which restricts a movement of the metal pipe material in an axial direction of the metal pipe material.