Four-Pressure Plastic Container Forming with Bottom Cooling
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Solution Overview
Problem
The existing methods for forming plastic preforms into containers face difficulties in shaping container bottoms, particularly when using multiple pressure levels, as there is insufficient time for cooling, and the recovery of blown air is partly in conflict with additional cooling requirements.
Innovation Solution
A method and apparatus that utilize at least four pressure levels for forming plastic containers, including a further intermediate blowing pressure stage, with asynchronous compressed air recycling and a fifth pressure reservoir for bottom cooling, allowing for efficient energy use and extended cooling phases without interfering with the high-pressure phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a further intermediate blowing pressure stage (Pi2) is added to improve energy efficiency, then energy consumption is reduced, but the cooling time for the container bottom becomes insufficient
Solution Approach 1:
The blowing process is segmented into five distinct pressure stages (P1, Pi1, Pi2, P2, and P3), with each stage serving a specific function. The additional intermediate stage Pi2 and bottom cooling stage P3 allow the system to maintain energy efficiency while dedicating specific time periods for cooling, thus resolving the contradiction between energy efficiency and cooling time.
Solution Approach 2:
The bottom cooling with pressure level P3 is initiated in advance and continues throughout the high-pressure blowing phase. This preliminary and continuous cooling action ensures that the container bottom receives sufficient cooling time even while the additional intermediate blowing stage Pi2 is implemented for energy efficiency.
2Temperature
If additional container cooling is provided in the blow molding machine, then cooling effectiveness is improved, but it conflicts with the recovery of blown air
Solution Approach 1:
The bottom cooling with pressure level P3 operates continuously throughout the high-pressure blowing phase rather than as a separate intermittent step. This continuous cooling action maintains effective cooling while allowing the system to recover blown air during other phases of the cycle, reducing conflict between cooling and air recovery.
Solution Approach 2:
The cooling process is integrated into the periodic blowing cycle, with different pressure levels applied at different phases. The P3 pressure level for bottom cooling is applied periodically in coordination with the blowing and air recovery phases, ensuring both cooling effectiveness and air recovery efficiency.
3Manufacturing precision
If four pressure levels are used for forming, then forming quality is improved, but the high-pressure phase duration is shortened reducing cooling effect
Solution Approach 1:
The bottom cooling function is merged with the high-pressure blowing phase by applying pressure level P3 simultaneously with pressure level P2. This combination allows the system to maintain four or more pressure levels for high forming quality while ensuring continuous cooling of the container bottom during the high-pressure phase, preventing the cooling effect from being reduced.
4Stability of the object's composition
If compressed air recycling is synchronized, then system coordination is improved, but it reduces the flexibility of pressure level application
Solution Approach 1:
The system employs dynamic pressure level application where each of the five pressure levels (P1, Pi1, Pi2, P2, P3) can be independently controlled and adjusted. The valve arrangements can be operated asynchronously to provide different pressure levels at different forming stations at different times, allowing the system to adapt to varying requirements while maintaining overall coordination through the control system.
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 ensures sufficient cooling of the container bottom even when using four pressure levels, improves energy efficiency, and allows for asynchronous air recycling, enhancing the overall blow molding process by maintaining the high-pressure phase while providing effective bottom cooling.
Implementation Method 1
Plastic preforms are usually applied with a flowable medium and in particular with compressed air in order to be formed into plastic containers
Implementation Method 2
at least four reservoirs which store the flowable and in particular gaseous medium and the plastic preforms being applied for their expansion with at least a first pressure level stored in the first pressure reservoir
Implementation Method 3
the forming stations each have a stretching rod, with which the plastic preforms are stretched in their longitudinal direction
Implementation Method 4
at least at times a bottom area of the plastic preform and/or plastic container is applied with the flowable medium and/or such an application takes place, in particular through the stretching rod
Data Source
AI summary
A method and device for forming plastic preforms into plastic containers has a plurality of forming stations each having application devices which apply a flowable medium at least a first pressure level, a second pressure level, a third pressure level and a fourth pressure level respectively, wherein the second pressure level is higher than the first pressure level, the third pressure level is higher than and the second pressure level and the fourth pressure level is higher than the third pressure level and wherein at least at times a bottom area of the plastic preform and/or plastic container is applied with the flowable medium.