Blow Molding Air Mass Flow Control for Wall Thickness
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Solution Overview
Problem
Existing blow molding methods for producing plastic containers struggle to achieve consistent wall thickness distribution due to reliance on direct pressure measurement for controlling the blowing process, which is not optimal for material distribution.
Innovation Solution
The method controls the blow molding process by regulating the mass flow of air according to a predetermined course, using a proportional valve to adjust the flow cross-section and ensure precise material distribution between the bottom and filling opening of the container.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct pressure measurement is used to control the blowing process, then the pressure can be monitored and readjusted, but the wall thickness distribution cannot be optimized precisely
Solution Approach 1:
The patent changes the control parameter from pressure to mass flow rate. By controlling the mass flow rate of blowing air according to a predetermined course, the invention achieves precise control over material distribution and wall thickness, resolving the contradiction between measurement capability and manufacturing precision.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the actual mass flow rate and comparing it with the predetermined course. The proportional valve adjusts the flow cross-section based on this feedback to maintain the desired mass flow rate profile, ensuring consistent wall thickness distribution.
2Manufacturing precision
If a proportional valve is used to regulate mass flow, then the material distribution can be precisely controlled, but the device complexity increases
Solution Approach 1:
The patent uses a proportional valve, a pneumatic/hydraulic control element, to regulate the mass flow rate of blowing air. This allows precise control of material distribution through flow cross-section adjustment, accepting the inherent device complexity as necessary for achieving the desired manufacturing precision.
3Manufacturing precision
If the mass flow course is changed during the blowing process, then the wall thickness distribution improves, but the process control complexity increases
Solution Approach 1:
The patent applies preliminary action by predetermined the mass flow rate course before the blowing process. The controller is programmed with the desired mass flow profile in advance, allowing the proportional valve to automatically follow this predetermined course during blowing, simplifying real-time control while achieving precise wall thickness distribution.
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 allows for the precise manufacturing of containers with desired wall thickness distribution, enabling real-time monitoring and adjustment during the process, and simplifies the recycling and venting of blown air.
Implementation Method 1
the blown air introduced into the preform or the bubble is controlled or optionally also regulated according to this predetermined course
Data Source
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AI summary
The invention describes a method for the production of containers (4) made of plastic in a blow-molding machine, wherein a pressurized air blast (2, 15) is introduced in a preform as a function of a predetermined order of the blowing process. In order to improve such a method with regard to the quality of the container obtained, the invention provides that a course of a mass flow of the air blast is specified as a function of the predetermined course of the blowing process, and the air blast is introduced in the preform corresponding to the specified course.