L-Shaped Sheet Metal Stamping via Segmented Forming

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Solution Overview

Problem

The existing methods for producing L-shaped members for automobile monocoque bodies face issues such as wrinkle generation and crack formation during stamping, which can be mitigated by using a drawing process but result in lower yield rates and higher production costs due to the need for larger blanks and lower-strength materials.

Innovation Solution

A method involving a two-step process using a drawing die assembly to create an intermediate product with controlled angles, followed by a bending die assembly to shape the L-shaped product, allowing for reduced material accumulation and suppression of wrinkles and cracks, enabling the use of high-strength steel sheets with smaller blanks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a drawing process is used to produce L-shaped members, then wrinkles and cracks are avoided, but the yield rate decreases and production cost increases due to larger blanks and lower-strength materials

Engineering Contradiction:
Improvequality of L-shaped memberVSAvoidyield rate
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The forming process is segmented into two distinct stages: first a drawing process to create an intermediate product with controlled geometry, then a bending process to achieve the final L-shaped configuration. This segmentation allows each stage to be optimized independently, preventing defects while improving material utilization

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The drawing process performs preliminary shaping to create an intermediate product with specific geometric characteristics (controlled angles and wall thickness distribution) that prepare the material for the subsequent bending operation, preventing wrinkles and cracks before they occur

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a drawing process is used to produce L-shaped members, then wrinkles and cracks are avoided, but production cost increases due to larger blanks and lower-strength materials

Engineering Contradiction:
Improvequality of L-shaped memberVSAvoidproduction cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The forming process is segmented into two distinct stages: first a drawing process to create an intermediate product with controlled geometry, then a bending process to achieve the final L-shaped configuration. This segmentation allows each stage to be optimized independently, preventing defects while improving material utilization

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The process changes the geometric parameters of the intermediate product (angles, wall thickness distribution) to optimize material flow and stress distribution during bending, enabling the use of smaller, more cost-effective blanks

Inventive Principle:
Principle #35Parameter changes

3Strength

If high-strength steel sheets with lower extensibility are used, then collision performance increases, but the blank thickness must be increased resulting in higher weight

Engineering Contradiction:
Improvecollision performanceVSAvoidframe structure weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The process changes the geometric parameters of the intermediate product (angles, wall thickness distribution) to optimize material flow and stress distribution during bending, enabling the use of smaller, more cost-effective blanks

Inventive Principle:
Principle #35Parameter changes

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 reduces the size of the blank required, prevents wrinkles and cracks, and allows for the use of high-strength materials, thereby enhancing the strength of the L-shaped product while minimizing weight and production costs.

Implementation Method 1

stamping the sheet metal material with the drawing die assembly to produce an intermediate product

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

stamping the intermediate product by the bending die assembly to produce the completed L-shaped product

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP2644293B1Method for manufacturing l-shaped product
Publication Date: 2016.07.27 NIPPON STEEL & SUMITOMO METAL CORP
  • EP2644293B1 patent drawingFigure 1~1A
  • EP2644293B1 patent drawingFigure 2
  • EP2644293B1 patent drawingFigure 3~5

AI summary

A method of producing an L-shaped product (10) which includes an L-shaped flat top wall (12), an inside wall (14) extending and connected along an inside edge (12c) of the top wall, and an outside wall (16) extending and connected along an outside edge (12d) of the top wall, each of the inside and outside walls being terminated by flange (18, 20) substantially parallel to the top wall, is disclosed. The method comprises the steps of: providing sheet metal material; providing a drawing die assembly; and stamping the sheet metal material by the drawing die assembly to produce an intermediate product. The method further comprises the steps of: providing a bending die assembly; and stamping the intermediate product by the bending die assembly to produce an L-shaped product completed.