Stretch Rod Position Detection for Boxing Phase Control
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Solution Overview
Problem
The existing stretch blow molding process for manufacturing containers with boxed bottoms is prone to inconsistencies, leading to quality defects such as deformation and material waste, particularly in HR applications, due to uncertainties in the boxing phase and material pinching between mold walls, which affects the reliability, repeatability, and production rates.
Innovation Solution
A method and apparatus for stretch blow molding that includes a movable mold bottom and a stretching rod, where the movement of the rod is used to detect the start and end of the boxing phase, allowing for precise control of the mold bottom's position and fluid flow, thereby improving the accuracy and automation of the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the boxing technique is used to form the mold base with a movable mold bottom, then complex shapes and deep arches can be formed, but the material can become pinched between the mold wall and base, leading to burrs and material waste
Solution Approach 1:
The patent implements feedback control by detecting the actual position of the stretch rod during boxing and using this information to adjust the mold bottom movement. Sensors monitor the stretch rod position, and the system automatically adjusts the boxing parameters to prevent material pinching while achieving the desired complex shapes and deep arches, thereby eliminating burrs and reducing material waste.
Solution Approach 2:
The patent applies preliminary action by pre-positioning the mold bottom and stretch rod according to detected parameters before the boxing operation begins. The system uses feedback from previous cycles to pre-adjust the timing and position of the mold bottom movement, ensuring that the material is properly positioned before the boxing force is applied, thus preventing pinching and burr formation.
2Manufacturing precision
If the boxing process parameters are manually fine-tuned, then container quality can be improved, but the process reliability and repeatability remain compromised due to uncertainties in material behavior
Solution Approach 1:
The patent implements feedback control by detecting the actual position of the stretch rod during boxing and using this information to adjust the mold bottom movement. Sensors monitor the stretch rod position, and the system automatically adjusts the boxing parameters to prevent material pinching while achieving the desired complex shapes and deep arches, thereby eliminating burrs and reducing material waste.
Solution Approach 2:
The patent replaces manual mechanical fine-tuning with an automated detection and control system. Sensors detect the stretch rod position, and a control system automatically adjusts the boxing parameters, eliminating the need for manual intervention and ensuring consistent, repeatable results despite variations in material behavior.
3Loss of time
If the stretch rod movement is not monitored, then the boxing phase timing is uncertain, but implementing monitoring increases device complexity
Solution Approach 1:
The patent implements feedback control by detecting the actual position of the stretch rod during boxing and using this information to adjust the mold bottom movement. Sensors monitor the stretch rod position, and the system automatically adjusts the boxing parameters to prevent material pinching while achieving the desired complex shapes and deep arches, thereby eliminating burrs and reducing material waste.
Solution Approach 2:
The patent uses the stretch rod itself as an intermediary for detection. By attaching a reflector to the stretch rod and using an optical sensor to detect its position, the system converts mechanical movement into optical signals for precise timing measurement, achieving accurate monitoring with minimal added 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 enhances the reliability and repeatability of the manufacturing process, reduces material waste, and improves the quality of containers by providing objective measurements for adjusting machine parameters, leading to increased production rates and better-formed container bottoms.
Implementation Method 1
a sensor, in particular an optical sensor such as a laser sensor, pointed towards the stretch rod (22) to detect at least the movement of the rod (22)
Implementation Method 2
injecting a fluid, such as a gas (generally air), under pressure into the blank through the neck to press the material against the wall of the mold
Implementation Method 3
a blow-drawing phase, during which a pressurized fluid is injected into the blank
Implementation Method 4
The rigidity of the container's side wall (or body) is generally achieved thermally by maintaining the body in contact with the mold wall heated to a predetermined temperature (usually above 100°C)
Implementation Method 5
This process, called heat setting, leads to an increase in the material's crystallinity, which in turn increases its rigidity
Data Source
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AI summary
The invention relates to a method for manufacturing a container (2) from a blank (3) made of plastic material, in a stretch-blow moulding unit (7) including: a mould (11) provided with a wall (13) and a mould base (14) which is axially movable relative to the wall (13) between a low position and a raised position; a stretch rod (22) which is axially movable relative to the mould (11) between a high position and a low position; said method including: a phase of inserting the blank (3) in the mould (11); a phase of stretch-blow moulding; a phase of boxing; a phase of determining the start and end of the boxing phase, respectively, by detecting the movement of the rod (22) from the low position thereof and the stopping of the rod (22) at the raised position thereof.