Pre-blowing Control for Plastic Vessel Quality

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Solution Overview

Problem

In the production of plastic vessels by blow-moulding or stretch blow-moulding, there is a challenge in achieving consistent quality and minimizing material usage while maintaining high production rates, often resulting in substantial scrap rates due to poor material distribution and pressure variations during the pre-blowing process.

Innovation Solution

A method that involves controlling the pre-blowing process by measuring and adjusting the pressure inside the preform to synchronize the real moment of pressure increase with a theoretical pre-blowing beginning moment, using an electrovalve control system to advance or delay the pre-blowing cue based on detected pressure changes, ensuring optimal material distribution and vessel quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the pre-blowing process is monitored and vessels with non-compliant pressure curves are rejected, then the overall quality of production is improved, but productivity is strained and material is wasted

Engineering Contradiction:

Improvevessel qualityVSAvoidproduction rate

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent implements a feedback mechanism by monitoring the pressure curve during pre-blowing and using this information to adjust the pre-blowing cue timing for subsequent vessels. The system detects the real moment of pre-blowing beginning by monitoring pressure variations and compares it with the theoretical moment, then adjusts the timing accordingly to maintain consistent material distribution without rejecting vessels

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies dynamics by making the pre-blowing cue timing adjustable and adaptive rather than fixed. The system dynamically modifies the pre-blowing cue based on detected pressure variations and measured differences between real and theoretical pre-blowing moments, allowing the process to adapt to variations in preform properties and maintain optimal material distribution

Inventive Principle:

Principle #15Dynamics

2Device complexity

If the pre-blowing cue timing is fixed according to theoretical calculations, then the control system is simple, but material distribution becomes inconsistent leading to poor vessel quality

Engineering Contradiction:

Improvecontrol system complexityVSAvoidmaterial distribution uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent uses feedback by continuously monitoring the pressure curve during pre-blowing and using this information to adjust the pre-blowing cue timing. The system measures the difference between the real pre-blowing moment (detected through pressure variations) and the theoretical moment, then applies this feedback to optimize subsequent pre-blowing timing for consistent material distribution

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies preliminary action by detecting the pre-blowing moment through pressure monitoring before the actual pre-blowing completes, and using this early detection to adjust timing parameters for optimal material distribution in subsequent cycles

Inventive Principle:

Principle #10Preliminary 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

This approach leads to improved and consistent vessel quality with reduced scrap rates, maintaining high production efficiency by aligning the pre-blowing process with precise pressure control, resulting in better material distribution and enhanced mechanical strength of the vessels.

Implementation Method 1

controlling the opening of an electrovalve for establishing a communication between the inside of the preform and a source of gas at a predetermined pre-blowing pressure

Methodology Applied

Scientific EffectGas injection under pressure: Pressurisation

Implementation Method 2

measuring the pressure inside the preform; detecting the so-called real moment of the beginning of the pre-blowing at which the pressure in the preform starts to increase

Methodology Applied

Scientific EffectPressure measurement:

Data Source

PatentUS9044889B2Method for producing vessels with feedback depending on the pre-blowing starting point

Publication Date: 2015.06.02 SIDEL PARTICIPATIONS SAS

AI summary

Method for producing a vessel (2) by blowing in a mould (11) from a preform (3) made of plastic material, comprising the operations consisting in:introducing the preform (3) into the mould;at a predetermined moment, called pre-blowing cue (tP), controlling the opening of an electrovalve (22) for establishing a communication between the inside of the preform (3) and a source (20) of gas at a predetermined pre-blowing pressure;measuring the pressure (P) inside the preform (3);detecting the so-called real moment (tA), of the beginning of the pre-blowing, at which the (P) in the preform (3) starts to increase;comparing this moment (tA) with a theoretical pre-blowing beginning moment;if the real moment (tA) of the beginning of the pre-blowing follows the theoretical pre-blowing beginning moment, advance the pre-blowing cue (tP);if the real moment (tA) of the beginning of the pre-blowing precedes the theoretical pre-blowing beginning moment, delay the pre-blowing cue (tP).