U-Cross-Section Tube Forming With Longitudinal Bending Control

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Solution Overview

Problem

Conventional UO-forming methods face challenges in producing bent tubes and irregular cross-section tubes due to issues like fracture, wrinkling, and creasing during the bending process, leading to low yields and shaping defects.

Innovation Solution

A method involving separate steps for U-forming and bending in the longitudinal direction, using tooling with a die, punch, and pads to apply external forces, ensuring the bottom part of the U-shaped article projects inside, and maintaining the rigidity of the metal plate to prevent wrinkling and creasing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If bending is performed in the longitudinal direction during U-forming to produce bent tubes, then the ability to produce complex 3D shapes is improved, but shaping defects such as fracture, wrinkling, and creasing occur

Engineering Contradiction:

Improveability to produce bent tubes and irregular cross-section tubesVSAvoidshaping defects including fracture, wrinkling, and creasing

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent divides the forming process into two distinct stages: first performing U-forming to create a U-shaped article with a straight bottom part, then performing a separate bending operation to bend the article in the longitudinal direction. This segmentation allows each operation to be optimized independently, preventing the shaping defects that occur when both operations are combined into a single step.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs U-forming as a preliminary action before bending. By first creating the U-shape with a straight bottom part, the workpiece is prepared in an optimal state for the subsequent bending operation. This preliminary shaping ensures that the material is properly positioned and oriented to withstand the bending forces without developing defects.

Inventive Principle:

Principle #10Preliminary action

2Shape

If external force is applied to bend the U-shaped article in the longitudinal direction, then bent shapes are achieved, but the bottom part may project outward causing shaping defects

Engineering Contradiction:

Improvebent shape in longitudinal directionVSAvoidbottom part projection causing creasing and deformations

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The patent applies external force in a direction connecting the edge and the bottom part during the bending operation. This preliminary anti-action counteracts the natural tendency of the bottom part to project outward, preventing creasing and deformations before they can occur. The external force is strategically applied to maintain proper geometry throughout the bending process.

Inventive Principle:

Principle #9Preliminary anti-action

3Productivity

If conventional UO-forming is used for straight shaped tubes, then simple shapes are produced efficiently, but bent tubes and irregular cross-section tubes cannot be formed

Engineering Contradiction:

Improveefficiency in producing straight shaped tubesVSAvoidinability to form bent tubes and irregular cross-section tubes

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent separates the U-forming operation from the bending operation into distinct steps. This allows the process to maintain the efficiency of conventional UO-forming for creating the basic U-shape while adding the capability to subsequently bend the article into complex 3D shapes including bent tubes and irregular cross-section tubes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic flexibility to the forming process by allowing the article to be bent in the longitudinal direction after U-forming. This dynamic capability enables the same basic process to produce both simple straight tubes and complex bent shapes, significantly increasing adaptability while maintaining productivity.

Inventive Principle:

Principle #15Dynamics

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

This approach effectively suppresses shaping defects and allows for the production of tubular shaped articles with uniform thickness distribution, enhancing the range of possible shapes and reducing the occurrence of fractures and wrinkling.

Implementation Method 1

pads arranged at side surfaces of the punch and compressing, in in-plane directions, at least parts of a planned bending part of the U-shaped article in end parts along the longitudinal direction

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

an external force in a direction connecting an edge and the bottom part is applied to at least a part of a planned bending part of the U-shaped article, at the same time as the bending

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS11148183B2Method of producing shaped article, tooling, and tubular shaped article

Publication Date: 2021.10.19 NIPPON STEEL CORPORATION

AI summary

A method of production of a shaped article able to suppress occurrence of shaping defects, that is, a method of production of a shaped article including a first step of press-forming a metal plate (1a) into a U-shape to obtain a U-shaped article (1b) having a bottom part (2) straight extending in a longitudinal direction and a second step of press-forming the U-shaped article (1b) to bend it in the longitudinal direction so that the bottom part (2) of the part projects to the inside and obtain a U-cross-section bent article (1c).