Stretching Rod Tip Support for Stable Preform Blow Molding

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Solution Overview

Problem

Existing injection stretch blow molding machines face issues with preform deformation and uneven thickness due to shrinkage during the molding process, leading to defects such as rupture and uneven wall thickness, which are exacerbated by variations in the minimum point of skin layer integration with the core layer.

Innovation Solution

A method involving a stretching rod with a distal end portion having a peripheral wall matching the inner preform shape, supported by a shoulder portion, is used to stabilize the preform until it reaches a suitable temperature for stretching, combined with a preform separation step using blow air to maintain consistent thickness and prevent deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the preform is allowed to cool and harden the skin layer during injection molding, then the preform structure is stabilized, but the preform undergoes shrinkage and deformation during subsequent handling and stretching

Engineering Contradiction:

Improveskin layer formationVSAvoidpreform shape accuracy

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent applies preliminary anti-action by providing preliminary support to the preform's inner peripheral wall during the cooling and hardening process. This preliminary support prevents the shrinkage and deformation that would otherwise occur as the skin layer forms and the preform cools, thereby maintaining shape accuracy while still allowing the skin layer to form properly.

Inventive Principle:

Principle #9Preliminary anti-action

2Productivity

If the preform is stretched and blown immediately after injection molding, then the molding cycle is shortened, but the preform temperature is not suitable for stretching causing deformation and rupture

Engineering Contradiction:

Improvemolding cycle timeVSAvoidhollow molded article quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by providing support to the preform's inner peripheral wall before the stretching and blowing operations. This preliminary support ensures that when stretching and blowing do occur, the preform maintains its shape and the skin layer integrates properly with the core layer, preventing deformation and rupture while allowing the process to proceed efficiently.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If the preform is supported during cooling to maintain shape, then manufacturing precision is improved, but the molding process becomes more complex

Engineering Contradiction:

Improvepreform shape accuracyVSAvoidmolding process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses an intermediary approach by introducing a support structure that temporarily supports the preform's inner peripheral wall during critical phases of the molding process. This intermediary support is provided through the stretching rod or blow core, which acts as a mediator between the preform and the molding environment, preventing deformation without requiring complex additional equipment.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 method effectively suppresses preform deformation and shortens the molding cycle by ensuring consistent skin layer thickness, reducing the time required for the preform to reach the appropriate temperature for stretching and blowing, thereby improving the quality and yield of hollow molded articles.

Implementation Method 1

the distal end portion of the stretching rod 20 supports the preform until a temperature appropriate for stretching is obtained

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a preform separation step of supplying blow air into the preform to release the contact between the preform and the distal end portion

Methodology Applied

Scientific EffectGas pressure: Pressure Increase

Implementation Method 3

The stretching rod presses down the side (barrel portion) and bottom portion of the preform, thereby stretching the preform

Methodology Applied

Scientific EffectMechanical force: Mechanical Force

Data Source

PatentUS20260061689A1Method for molding hollow molded article, and stretching rod and injection stretch blow molding machine used in the method

Publication Date: 2026.03.05 A K TECH LAB INC

AI summary

A method for molding a hollow molded article, which can suppress deformation of a preform and shorten a molding cycle of the hollow molded article, and a stretching rod and an injection stretch blow molding machine used in the method are provided. The method for molding a hollow molded article, includes: an injection molding process of injection molding a preform; and a blow molding process of obtaining a hollow molded article by stretch blow molding the preform in a blow molding section. The blow molding process includes a preform supporting step of inserting a distal end portion of a stretching rod into the preform and bringing the distal end portion into contact with the preform to support the preform, and a preform separation step of supplying blow air into the preform to release the contact between the preform and the distal end portion.