Stretch-Blow Molded Handle Container With Reinforced Weld Bead

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Solution Overview

Problem

Plastic containers with integrated handles often have weak seams that can create a point of failure under heavy loads, particularly in uncontrolled handling environments like mail order, leading to potential container instability and susceptibility to impacts.

Innovation Solution

A stretch-blown plastic container design featuring a bead of molten material placed between walls to reinforce the connection, formed through high-frequency or friction welding, which fills gaps and bridges curvatures, creating a continuous, strong bond that reduces stress concentrations and prevents peeling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a two-stage blow molding process is used to produce containers with complex shapes and integrated closures, then manufacturing precision and product quality are improved, but device complexity and production time increase

Engineering Contradiction:
Improvecontainer shape precisionVSAvoidmolding process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The molding process is divided into two distinct stages: a first blow molding stage to form the container body, and a second blow molding stage to form the closure and final shape. This segmentation allows each stage to be optimized independently, with the first stage focusing on body formation and the second stage focusing on closure integration, thereby achieving high precision without excessive overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The container body is pre-formed through the first blow molding stage before the second stage begins. This preliminary action establishes the basic container structure, allowing the second stage to focus solely on adding the closure and final shaping, which simplifies the overall process by breaking down the complex task into manageable sequential steps.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If a two-stage blow molding process is used to produce containers with complex shapes and integrated closures, then manufacturing precision and product quality are improved, but production time increases

Engineering Contradiction:
Improvecontainer shape precisionVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The molding process is divided into two distinct stages: a first blow molding stage to form the container body, and a second blow molding stage to form the closure and final shape. This segmentation allows each stage to be optimized independently, with the first stage focusing on body formation and the second stage focusing on closure integration, thereby achieving high precision without excessive overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The two blow molding stages are performed in sequence without interruption, with the container remaining in the mold throughout both stages. This continuous action eliminates idle time between operations and ensures that the container is constantly being formed and shaped, maximizing productive use of time while achieving the required precision through the two-stage approach.

Inventive Principle:
Principle #20Continuity of useful action

3Device complexity

If conventional one-stage blow molding is used, then device complexity is reduced, but manufacturing precision and closure integration quality deteriorate

Engineering Contradiction:
Improvemolding process complexityVSAvoidcontainer shape precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The molding process is divided into two distinct stages: a first blow molding stage to form the container body, and a second blow molding stage to form the closure and final shape. This segmentation allows each stage to be optimized independently, with the first stage focusing on body formation and the second stage focusing on closure integration, thereby achieving high precision without excessive overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first blow molding stage optimizes for the container body formation with appropriate pressure, temperature, and mold configurations, while the second stage specifically optimizes for closure formation and final shaping. This local quality approach allows each stage to be tailored to the specific requirements of the portion being formed, achieving high precision for both body and closure without requiring the entire process to be overly complex.

Inventive Principle:
Principle #3Local quality

4Loss of time

If conventional one-stage blow molding is used, then production time is reduced, but manufacturing precision and closure integration quality deteriorate

Engineering Contradiction:
Improveproduction timeVSAvoidcontainer shape precision
Core Design Contradiction:
Loss of timeVSManufacturing precision

Solution Approach 1:

The molding process is divided into two distinct stages: a first blow molding stage to form the container body, and a second blow molding stage to form the closure and final shape. This segmentation allows each stage to be optimized independently, with the first stage focusing on body formation and the second stage focusing on closure integration, thereby achieving high precision without excessive overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The two blow molding stages are performed in sequence without interruption, with the container remaining in the mold throughout both stages. This continuous action eliminates idle time between operations and ensures that the container is constantly being formed and shaped, maximizing productive use of time while achieving the required precision through the two-stage approach.

Inventive Principle:
Principle #20Continuity of useful action

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 bead enhances the container's stability and resistance to impacts by sealing off gaps and bridging curvatures, ensuring a secure and durable connection between walls, even under high loads.

Implementation Method 1

a parison (blow-molded tube) stretched and blown to expand

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

with substantially uniform wall thickness throughout the container wall, except at the container bottom

Methodology Applied
Scientific EffectPlasticity: Plasticity

Data Source

PatentEP4392337B1Stretch-blow-molded plastic container and method for producing same
Publication Date: 2026.04.29 ALPLA WERKE ALWIN LEHNER
  • EP4392337B1 patent drawingFigure 1~2B
  • EP4392337B1 patent drawingFigure 3~5
  • EP4392337B1 patent drawingFigure 6~8

AI summary

The invention relates to a stretch-blow-molded plastic container (100) with a container body (20), which forms a filling volume (F), and a handle (21), which is formed on the container body. In order to form the handle (21), a first sub-region (221) of a first wall (22) of the container body (20) is bonded to a second sub-region (231) of a second wall (23) of the container body (20) lying opposite the first wall (22). The filling volume (F) extends circumferentially about the bonded connection. A bead (31) made of melted material is arranged within the filling volume between the first wall (22) and the second wall (23).