Hollow Stabilizer Bend Geometry to Limit Pipe Flattening

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Solution Overview

Problem

Conventional methods for forming a hollow stabilizer using a die result in a bent part with excessive flatness, leading to stress distribution issues and interference with surrounding parts, as the pipe bender's grip length limitations make it difficult to achieve a short distance between the arm and bent parts.

Innovation Solution

A hollow stabilizer with a cross-sectional design featuring multiple curvature regions and a specialized manufacturing device comprising a base die, clamp die, pressing die, and moving die to restrict flatness and control bending, allowing for a bent part with a flatness within ±10% of the pipe diameter and reduced stress variation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a pipe bender with a pipe clamp is used to bend the pipe, then the grip length at the pipe end must be sufficient, but this makes it difficult to achieve a short distance from the distal end of the arm part to the bent part

Engineering Contradiction:
Improvedistance from distal end of arm part to bent partVSAvoiddifficulty of bending with pipe bender
Core Design Contradiction:
Length of moving objectVSEase of manufacture

Solution Approach 1:

The patent replaces the pipe bender mechanical system with a die-based bending system. The die directly forms the bent part by applying localized force to the pipe, eliminating the need for a pipe clamp grip section. This substitution enables bending at locations closer to the pipe end while maintaining manufacturing feasibility.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If a conventional die is used to push and bend the pipe in the radial direction, then the bent part can be formed, but the bent part becomes excessively flat

Engineering Contradiction:
Improveability to form bent part with dieVSAvoidflatness of bent part
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The die is designed with a curved surface that matches the desired circular cross-section geometry of the bent part. This localized curvature on the die surface applies distributed pressure that maintains the circular shape of the pipe cross-section during bending, preventing excessive flatness while enabling formation of the bent part.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If the bent part has large flatness, then the manufacturing process is simpler, but the stress distribution in the bent part becomes problematic and may interfere with surrounding parts

Engineering Contradiction:
Improvesimplicity of bending processVSAvoidstress distribution and interference with parts
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent employs a hydraulic press to apply controlled, distributed pressure through the die during the bending process. This hydraulic force system enables precise control of the bending action, maintaining the circular cross-section geometry and ensuring uniform stress distribution in the bent part, thereby preventing both excessive flatness and stress concentration.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 suppresses flatness and stress distribution variation in the bent part, forming a shape closer to a perfect circle, which enhances the stabilizer's durability and reduces interference with other components.

Implementation Method 1

the arm parts, the bent part, and the torsion part are elastically deformed against the rolling behavior of the vehicle body that occurs when the vehicle travels on a curve, and function as springs

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3603835B1Hollow stabilizer, stabilizer manufacturing device, and method for manufacturing hollow stabilizer
Publication Date: 2024.12.04 NHK SPRING CO LTD
  • EP3603835B1 patent drawingFigure 1~2
  • EP3603835B1 patent drawingFigure 3~4
  • EP3603835B1 patent drawingFigure 5

AI summary

A hollow stabilizer (10) includes a curved part (21) having eight regions (S1 to S8) defined in a circumferential direction in a cross section taken in a pipe radial direction. A first region (S1) includes a 90° first part (No. 1) when the center of the inside of the curve is taken to be at 0° and the center of the outside of the curve is taken to be at 180°. A third region (S3) includes a 0° third part (No. 3). A fifth region (S5) includes a 270° fifth part (No. 5). A seventh region (S7) includes a 180° seventh part (No. 7). The radii of curvature (R3, R7) of the respective outer surfaces of the third part (No. 3) and the seventh part (No. 7) are larger and the radii of curvature (R2, R6) of the respective outer surfaces of the second part (No. 2) and the sixth part (No. 6) are smaller than the radii of curvature (R4, R5) of the respective outer surfaces of the fourth part (No. 4) and the fifth part (No. 5).