Blow Molding Thickness Control via Real-Time Feedback
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Solution Overview
Problem
Existing methods for manufacturing containers by blow molding or stretch blow molding are inefficient and require significant manual adjustment of parameters, leading to lengthy production times and potential nonconformities in container quality.
Innovation Solution
A method that automatically adjusts the thermal conditioning of preforms and container forming parameters in real-time by measuring the thickness of containers at multiple heights, comparing these measurements to setpoint values, and modifying driving parameters to achieve optimal thickness distribution without stopping production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual adjustment of manufacturing parameters is performed to ensure container conformity, then manufacturing precision is improved, but loss of time increases and productivity decreases
Solution Approach 1:
The control system automatically adjusts manufacturing parameters by processing thickness measurements and determining optimal parameter sets without operator intervention. The system selects from pre-defined parameter sets based on measured thickness deviations, enabling self-service parameter optimization that eliminates manual adjustment time while maintaining container conformity.
Solution Approach 2:
The system implements feedback by measuring container wall thickness, comparing it to target values, and using this information to automatically select and adjust manufacturing parameters. This closed-loop feedback mechanism ensures container conformity while reducing the time required for parameter adjustment compared to manual trial-and-error methods.
2Manufacturing precision
If multiple parameters are adjusted manually to correct thickness defects, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The control system automatically manages the complexity of adjusting multiple parameters by processing thickness measurements and autonomously selecting appropriate parameter sets from pre-defined options. This self-service approach handles the computational complexity of coordinating multiple parameter adjustments without requiring complex manual intervention or sophisticated real-time calculation systems.
Solution Approach 2:
The system adjusts parameters partially by selecting from pre-defined parameter sets rather than continuously tuning all parameters. This partial action approach achieves sufficient thickness correction without requiring full complex adjustment of all possible parameters, thereby reducing the effective device complexity while maintaining manufacturing precision.
3Manufacturing precision
If production is stopped to adjust parameters for new container formats, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
Multiple format-specific parameter sets are pre-defined and stored in the control system before production begins. When a format change is detected through thickness measurement, the system quickly selects the appropriate pre-prepared parameter set without requiring time-consuming manual reconfiguration or production stoppage, thus maintaining both precision and productivity.
Solution Approach 2:
The system dynamically adapts to different container formats by automatically detecting format changes and switching between pre-defined parameter sets in real-time during production. This dynamic adaptation eliminates the need to stop production for parameter reconfiguration, allowing continuous operation while maintaining format-specific optimization.
4Manufacturing precision
If operator knowledge and expertise are required for parameter adjustment, then manufacturing precision is improved, but ease of operation decreases
Solution Approach 1:
The control system performs the complex task of parameter optimization automatically by processing thickness measurements and selecting appropriate parameter sets without operator intervention. This eliminates the need for operators to possess specialized knowledge of parameter relationships while maintaining high manufacturing precision through automated decision-making.
Solution Approach 2:
The system replaces the human operator's cognitive and decision-making processes with automated computational logic. Instead of relying on operator expertise to interpret thickness measurements and select parameters, the control system uses programmed algorithms to automatically determine optimal parameters, thereby improving ease of operation while maintaining precision.
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 method enables rapid correction of defects and optimization of container production parameters, reducing production time and maintaining high-quality container production without manual intervention.
Implementation Method 1
a first so-called preform heating phase, during which a succession of preforms is heated in the heating unit to a reference temperature
Implementation Method 2
a fluid under pressure is injected into each preform by the injection device, also called corresponding nozzle, to give the preform the final form of the container
Implementation Method 3
a stretching phase performed by means of a movable stretching rod arranged to apply a stretching force onto the bottom of a preform in a mold
Data Source
AI summary
The present invention relates to a method for manufacturing containers from thermoplastic materials by blow moulding or extrusion blow moulding a preform that has been pre-heated in a furnace then placed in a mould consisting of two half-moulds that define a moulding cavity, said preform being blown into the mould, optionally with a pre-blowing step. Said steps of heating the preforms, pre-blowing and blowing are controlled by a control unit on the basis of various control parameters such as the temperature in the furnace, the blowing pressure in the mould and/or the pre-blowing pressure and/or the pre-blowing flow rate and/or the speed of the stretching rod, for example. Said method is characterised in that it comprises at least the following steps: i) measuring the wall thickness of said containers at at least two different heights upon exiting the mould; ii) comparing the thickness measurements with setpoint values determined for each height of the containers; iii) if the difference between the thickness measurements and the determined setpoint values is greater than a determined threshold, modifying at least one of the control parameters, said modified control parameter(s) being selected at least by calculating the theoretical effects of the variation for each parameter on the thicknesses, then selecting the parameter or parameters that cause the smallest difference between the measured thickness values and the theoretical thickness values; iv) steps i) to iii) are repeated until the differences between the thickness measurements and the determined setpoint values are below said determined threshold.