Blow Molding Wall Thickness Control via Radiant Heater Feedback
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Solution Overview
Problem
The existing blow molding processes for thermoplastic containers face challenges in achieving consistent heat distribution and wall thickness, requiring manual adjustments and being time-consuming, especially with fluctuations in ambient temperature or humidity.
Innovation Solution
An automatic control system is implemented, using wall thickness sensors and temperature measurements to adjust the heating capacity of radiant heaters, ensuring precise wall thickness control through a cascade control system, which integrates inner and outer closed-loop control systems for temperature and wall thickness management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If manual adjustments are used to control heating capacity, then flexibility in adapting to environmental changes is achieved, but production time increases and productivity decreases
Solution Approach 1:
The patent implements automatic feedback control systems that continuously monitor wall thickness and temperature, comparing actual values with target values and automatically adjusting heating capacity accordingly. This eliminates manual intervention while maintaining adaptability to environmental changes, thus resolving the contradiction between adaptability and productivity.
Solution Approach 2:
The patent replaces manual mechanical adjustment systems with automated electronic control systems including programmable logic controllers (PLC) and computer-based control systems. This substitution enables rapid automatic responses to environmental changes without the time consumption associated with manual adjustments, thereby maintaining adaptability while significantly improving productivity.
2Manufacturing precision
If multiple radiant heaters are used to improve heat distribution, then wall thickness uniformity improves, but system complexity increases
Solution Approach 1:
The patent divides the heating system into multiple independent radiant heater zones arranged along the preform conveyance path, with each zone controllable separately. This segmentation enables precise local temperature control to achieve uniform wall thickness while maintaining manageable system complexity through modular design and independent control of each zone.
Solution Approach 2:
The patent applies different heating capacities to different zones along the preform based on specific thermal requirements of each region. By providing locally optimized heating rather than uniform heating, the system achieves improved wall thickness uniformity while avoiding the need for excessive complexity through targeted rather than universal control.
3Manufacturing precision
If wall thickness measurement and automatic control are implemented, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The patent incorporates wall thickness measurement systems that provide real-time feedback to the control system, enabling automatic adjustment of heating parameters. This feedback mechanism achieves high manufacturing precision while the automated nature of the control reduces operational complexity despite increased system sophistication.
Solution Approach 2:
The control system automatically monitors wall thickness measurements and self-adjusts heating capacity without external intervention. This self-service capability achieves precise wall thickness control while minimizing the need for complex manual operation and monitoring, effectively managing system complexity.
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 solution enables high-quality, high-speed production of blow-molded containers with precise wall thickness and temperature control, minimizing manual intervention and adapting to environmental changes.
Implementation Method 1
the thermal conditioning is carried out by several radiant heaters arranged one above the other
Implementation Method 2
the preform, which has first been brought to a desired temperature, is expanded into a container by biaxial orientation. The expansion is effected by means of compressed air, which is introduced into the preform to be expanded.
Data Source
AI summary
The process and the apparatus serve for the blow moulding of containers (2). A parison (1) composed of a thermoplastic material is first subjected to heat conditioning along a transport path in the region of a heating section (30). The parison is then subjected to a forming process within a blow mould with exposure to blowing pressure to give heat container. The heat conditioning of the parisons is carried out by a plurality of mutually superposed radiant heaters (41). The blow moulding of the container is followed by wall-thickness measurement at at least one level within the height of the container. The heating power of a radiant heater associated with this height level is controlled. The control system receives a prescribed wall-thickness value as required value and the measured wall thickness as actual value.