Resin Preform Cooling for Faster Blow Molding Without Sink Marks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The hot parison blow molding method faces challenges in shortening the molding cycle due to the cooling time of the preform, which promotes shrinkage and sink marks, and extending the injection molding time to prevent sink marks lengthens the cycle further.
Innovation Solution
The method involves injecting a resin preform, adjusting its temperature without cooling in the injection molds, and performing blow molding on the temperature-adjusted preform using a refrigerant to cool it efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the preform is cooled in injection molds without pressure holding to shorten the molding cycle, then the molding cycle is shortened, but shrinkage is promoted and sink marks occur
Solution Approach 1:
The patent applies preliminary action by performing pressure holding during the injection molding process before cooling. This ensures that the preform is properly consolidated and dimensional stability is achieved while the material is still hot and pliable, preventing sink marks from forming during subsequent cooling without extending the overall cycle time
Solution Approach 2:
The patent implements periodic action by dividing the injection molding process into distinct phases: filling, pressure holding, and cooling. Each phase is optimized independently - pressure holding is applied periodically during filling to prevent sink marks, then cooling follows to shorten the cycle, achieving both quality and productivity goals
2Manufacturing precision
If the filling and pressure holding time is lengthened to reduce sink marks, then sink marks are reduced, but the injection molding time is extended
Solution Approach 1:
The patent applies parameter changes by optimizing the pressure holding time and temperature parameters during injection molding. By maintaining appropriate pressure and temperature parameters during the critical filling phase, the preform achieves dimensional stability without requiring excessive holding time, thus reducing sink marks while keeping the injection molding cycle efficient
Solution Approach 2:
The patent implements local quality by applying pressure holding specifically during the filling phase where sink marks are most likely to occur, rather than extending pressure holding throughout the entire cooling phase. This localized application of pressure ensures quality at critical areas without unnecessarily extending the overall molding time
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 reduces sink marks, shortens the molding cycle, and improves the manufacturing efficiency by eliminating the need for cooling in the injection molds, allowing for high-speed production with reduced material consumption.
Implementation Method 1
a refrigerant is introduced into the preform to cool the preform
Data Source
AI summary
A method for manufacturing a resin container includes: performing injection molding on a resin preform; adjusting a temperature of the preform manufactured in the performing injection molding; and performing blow molding on the temperature-adjusted preform to manufacture the resin container. In the performing injection molding, injection molds are opened after completion of filling and pressure holding of a resin material, and the preform is taken out without being cooled in the injection molds after the completion of filling and pressure holding. In addition, in the adjusting the temperature, a refrigerant is introduced into the preform to cool the preform.