Dynamic Pressure Control in Blow Molding
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Solution Overview
Problem
Incremental pressure methods in blow molding and stretch-blow molding processes result in slower pressure rise and fall, making it difficult to achieve small shape details and complicating production adjustments, while also reducing energy savings and production efficiency.
Innovation Solution
A method that optimizes the sequencing of pressure increments by selecting characteristic points on the pressure curve and determining triggering criteria to adjust the timing of sub-phases in the blow molding and recovery processes, allowing for improved control over the pressure transitions and energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If incremental pressure methods are used in blow molding, then energy savings are improved and intermediate-pressure air sources can be used, but the pressure rise and fall become slower
Solution Approach 1:
The patent implements dynamic control of pressure transitions by adjusting the sequencing and timing of pressure increments based on real-time monitoring of the container's deformation state. The control system dynamically modifies the duration and magnitude of each pressure stage to optimize both energy efficiency and molding speed, rather than using fixed incremental pressure steps.
Solution Approach 2:
The patent changes the parameters of pressure application by introducing multiple controllable pressure stages with variable durations and intensities. By modifying pressure parameters dynamically during the molding process and optimizing the transition timing between stages, the system achieves both energy savings and maintained molding speed.
2Loss of energy
If incremental pressure methods are used in blow molding, then energy savings are improved and intermediate-pressure air sources can be used, but the manufacturing precision deteriorates due to reduced flattening time
Solution Approach 1:
The system dynamically adjusts the pressure application profile to maintain optimal flattening time at each stage. By实时监控 the container's deformation and mold contact, the control system modifies pressure increments to ensure sufficient time for achieving small shape details while still benefiting from energy-efficient incremental pressure building.
Solution Approach 2:
The patent applies preliminary pressure stages that gradually prepare the container for final high-pressure molding. These preliminary actions allow the material to progressively deform and conform to the mold, ensuring that when maximum pressure is applied, the container has already achieved proper positioning and contact, thereby maintaining manufacturing precision.
3Productivity
If the sequencing of pressure increments is optimized to maintain production speed, then productivity is improved, but the device complexity increases due to complicated adjustments
Solution Approach 1:
The patent incorporates feedback mechanisms that automatically monitor pressure levels, container deformation, and timing parameters. The control system uses this feedback to self-adjust the pressure increment sequencing, eliminating the need for complex manual adjustments and operator intervention while maintaining optimized production speed.
Solution Approach 2:
The control system performs self-optimization of the pressure increment sequencing by automatically analyzing process data and adjusting parameters. This self-service capability reduces the complexity burden on operators and simplifies the overall device operation while maintaining high productivity through continuously optimized pressure profiles.
4Manufacturing precision
If characteristic points are selected and triggering criteria are determined for each production cycle, then the quality of containers is improved, but the measurement and control complexity increases
Solution Approach 1:
The system uses feedback from pressure sensors and deformation monitors to automatically identify characteristic points on the pressure curve. The control system processes this data to determine optimal triggering criteria for each production cycle, reducing the need for manual pressure curve analysis while improving container quality through precise, data-driven control.
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 enhances the quality of containers produced, maintains or increases production speed, and optimizes energy savings by optimizing the timing of pressure transitions and energy recovery in the blow molding process.
Implementation Method 1
a preform or an intermediate container of synthetic material such as PET (polyethylene terephthalate) is brought to a temperature above the glass transition temperature of the material
Implementation Method 2
Air under high pressure—on the order of 40 bar—is introduced into the preform or the intermediate container whose wall expands until it is flattened against the mold to be formed
Implementation Method 3
the lowering of pressure can take place incrementally. This makes it possible for the air of the container that is compressed at high pressure to empty into the intermediate-pressure system and makes it possible to recover a portion of the energy
Data Source
AI summary
A method and machine for blow-moulding containers, the method involves selecting at least one characteristic point of the pressure in the container; for each selected point, defining a triggering criterion, and a pre-defined value thereof; during a production and data acquisition cycle, measuring the pressure in the container; for each selected point, defining a setpoint time for triggering, in the subsequent production cycle, the switch to the sub-phase after the characteristic point, such that: if the actual value of the criterion is ≤ to the pre-defined value, the setpoint time is the time at which the criterion has assumed a value equal to the predefined value, and if the actual value of the criterion is strictly higher than the pre-defined value, the setpoint time is after the actual time and is defined such that, at that time, the criterion assumes a value close to or coinciding with the pre-defined value.