Blow Molding Apparatus Pressure Control
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Solution Overview
Problem
The existing blow molding apparatus experiences a water hammer phenomenon when using a servo plunger-type pump to supply pressurized content liquid, leading to peak pressures exceeding 10 MPa, which deteriorates moldability and stability of the preform.
Innovation Solution
A blow molding apparatus with a controller that adjusts the actuation rate and force of the plunger pump to regulate the peak pressure of the liquid supplied into the preform between 3.5 MPa to 5.0 MPa, preventing the water hammer phenomenon by reducing the actuation rate and force after a predetermined time period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the actuation rate of the plunger pump is increased to pressurize the liquid quickly, then the pressurization speed is improved, but the water hammer phenomenon occurs causing peak pressure to exceed 10 MPa
Solution Approach 1:
The plunger pump's actuation rate is dynamically adjusted during the pressurization process. The controller increases the actuation rate to a first rate for initial pressurization, then switches to a second (lower) actuation rate after a predetermined time period, preventing water hammer while maintaining efficient pressurization speed
Solution Approach 2:
The pressurization process is divided into distinct phases with different actuation rates. The controller switches between high and low actuation rates at predetermined time points, creating a periodic action pattern that prevents water hammer phenomenon while maintaining overall pressurization efficiency
2Productivity
If the actuation rate of the plunger pump is increased to pressurize the liquid quickly, then the productivity is improved, but the peak pressure reaches approximately 10 MPa which deteriorates moldability
Solution Approach 1:
The actuation rate is dynamically adjusted in two stages: initially high to ensure productivity, then reduced after a predetermined time period to maintain peak pressure within the optimal range (3.5-5.0 MPa) for moldability, thus balancing productivity and manufacturing precision
Solution Approach 2:
The actuation rate parameter is changed at a predetermined time point from a first rate to a second rate. This parameter change ensures that peak pressure remains within the optimal range for moldability while maintaining efficient pressurization speed, resolving the contradiction between productivity and manufacturing precision
3Productivity
If the actuation rate of the plunger pump is increased to pressurize the liquid quickly, then the productivity is improved, but the stability of blow molding deteriorates
Solution Approach 1:
The actuation rate is dynamically adjusted during the pressurization process. The controller uses a higher actuation rate initially for productivity, then switches to a lower rate after a predetermined time period to stabilize the blow molding process, preventing excessive pressure fluctuations that would compromise stability
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 moldability and stability of the preform by preventing excessive pressure surges, ensuring accurate and precise molding while maintaining the stability of the blow molding process.
Implementation Method 1
a plunger pump configured to supply the pressurized liquid into the preform through the blow nozzle
Implementation Method 2
a water hammer phenomenon (i.e., a fluid hammer effect) might occur during the supply of the pressurized liquid into the preform
Data Source
AI summary
A blow molding apparatus that supplies a pressurized liquid into a bottomed tubular preform fitted to a mold used for blow molding and molds the preform into a shape conforming to a cavity of the mold, the blow molding apparatus including: a blow nozzle fitted to a mouth tubular portion of the preform; a plunger pump configured to supply the pressurized liquid into the preform through the blow nozzle; and a control device configured to change an actuation rate and an actuation force of the plunger pump during the supply of the pressurized liquid into the preform to regulate a peak pressure of the liquid supplied into the preform to be from 3.5 MPa to 5.0 MPa.