Preform Calibration via Air-Pressured Nipples
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Solution Overview
Problem
In injection molding, preforms are removed from molds in a dimensionally unstable state, leading to thermal stresses and shape changes, and existing cooling methods often result in uneven cooling and potential damage due to robotic intervention, which complicates the after-cooling process and extends the injection molding cycle time.
Innovation Solution
An auxiliary device with a gripper featuring multiple nipples is used for precise handling and calibration of preforms, employing air pressure and suction to maintain contact with the cooling sleeve without applying compressive forces, ensuring uniform cooling and dimensional accuracy without pressure points or deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If preforms are removed from molds in a dimensionally unstable state to reduce cycle time, then productivity increases, but thermal stresses and shape changes occur leading to potential damage
Solution Approach 1:
The patent applies preliminary action by providing preliminary support structures within the mold cavity that maintain preform shape during the critical cooling phase. These support elements are in place before the preform becomes fully stable, preventing thermal deformation during the dimensionally unstable period, thereby enabling earlier removal without damage.
Solution Approach 2:
The patent changes physical parameters by controlling the cooling rate and temperature distribution within the mold cavity. By adjusting these thermal parameters and providing structural support during specific temperature ranges, the preform maintains dimensional stability despite early removal, resolving the contradiction between cycle time reduction and reliability.
2Extent of automation
If robotic grippers are used to handle hot preforms, then automation increases, but compressive forces can cause mold damage
Solution Approach 1:
The patent introduces an intermediary support structure within the mold cavity that acts as a mediator between the preform and external handling forces. This internal support system distributes and absorbs compressive forces during the critical handling phase, allowing automated grippers to operate without causing damage to either the preform or mold.
Solution Approach 2:
The patent applies beforehand cushioning by providing protective support structures and force-distributing mechanisms in place before handling occurs. These pre-positioned elements cushion against compressive forces from robotic grippers, preventing damage while maintaining automation benefits.
3Temperature
If intensive water cooling is applied in injection mold halves, then cooling efficiency increases, but non-uniform cooling causes reheating and crystal formation
Solution Approach 1:
The patent applies local quality by providing differentiated cooling zones and support structures at specific locations within the mold cavity. Instead of uniform cooling throughout, targeted cooling regions address local thermal gradients and stress concentrations, preventing reheating and crystal formation while maintaining overall cooling efficiency.
Solution Approach 2:
The patent incorporates feedback mechanisms through temperature sensing and controlled cooling regulation. By monitoring temperature distribution and adjusting cooling intensity accordingly, the system maintains uniform cooling rates, preventing the thermal gradients that lead to reheating and crystallization.
4Ease of operation
If preforms are cooled horizontally in the aftercooler, then handling is simplified, but uneven cooling and ovalization occur
Solution Approach 1:
The patent applies dynamics by enabling dynamic adjustment of preform position and orientation during cooling. The system can transition between horizontal and vertical positioning, or adjust support contact points, to maintain geometric accuracy while preserving the ease of horizontal handling in the aftercooler configuration.
Solution Approach 2:
The patent changes operational parameters by adjusting cooling contact pressure, support location, and preform orientation during the cooling process. These parameter modifications prevent ovalization while maintaining the simplified horizontal handling configuration in the aftercooler.
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 significantly reduces the injection molding cycle time by up to 30% while maintaining high quality standards, allowing for earlier demolding of preforms in a dimensionally stable state without damage, and ensures precise geometric shape restoration.
Implementation Method 1
employing air pressure and suction to maintain contact with the cooling sleeve
Implementation Method 2
employing air pressure and suction to maintain contact with the cooling sleeve
Implementation Method 3
transferred to removal sleeves or cooling sleeves for external cooling
Data Source
Figure 1~2b
Figure 3a~3b
Figure 4a~4c
AI summary
An injection moulding assembly produces plastic preforms and has an adapter with numerous nipples (30), with radially expanding press/sealing rings (56) that are inserted into the sleeve-shaped components. When inactive, the sleeves float slightly. Assembly is an auxiliary robotic device for finishing and calibrating preforms (10) on removal from a multiple tool in an unstable shape, the calibration process being performed with the aid of compressed air immediately after removing and withdrawing the preforms (10) from the multiple tool. Nipples inserted into the preforms (30) have expandable press/sealing rings (56) sealing the interior of the preform (10) blow-moulded section. Compressed air enters via nipples (30). The seal is effected by radial expansion of the rings (56), preventing distortion of the preforms (10). The blow-moulded part (43) interior section is sealed without detriment to strength and shape. Areas not supported by the cooling sleeves are pre-externally strengthened by cool air as the preforms are transferred to the moving sleeves or cooling sleeves. Further claimed is a commensurate operating process to cool preforms consisting of a threaded section, a neck section and a blown section. During the calibration process press rings or sealing rings are accurately applied to the nipples and inserted into the preform in the zone between the threaded section and blown section, and inflated until contact is established. A resulting inner radial force causes the blown section to be sealed externally against the form.