An Analysis of Plunger Temperature during Glass Parison Pressing
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1 An Analysis of Plunger Temperature during Glass Parison Pressing P. Lankeu-Ngankeu and E. Gutierrez-MiraveteDepartment of Engineering and ScienceRensselaer at Hartford
2 IntroductionGlass container forming is done using two sets of mold: Blank and Blow moldsThere are two main processes used in container forming Blow and Blow and Press and BlowThe parison is formed in the blank mold and blown into the final bottle shape in the blow moldIn the Press and Blow process, the parison is created by driving a metal plunger into the loaded gobThe plunger needs to be at a prescribed operating temperature to avoid causing checks.Objective: Model the temperature on the plunger outside surface during the pressing cycle of the glass
3 Glass Bottle Forming Processes Press and Blow ProcessBlow and Blow Process
4 MotivationModeling and Plunger Temperature during Glass Parison PressingHeating of the plunger outside surface due to glass contact.Cooling from the cooling tube on the inside surface of the plunger.Temperature change on the plunger outside surface due to cyclical contact with the glass gob.Plunger
5 Model DescriptionModel of a Emhart Glass Research Center (EGRC) longneck beer plungerTwo cases:A 2D axissymmetric modelA full 3D model1s duration for gob loading (the glass is not in contact with the plunger surface~cooling cycle).1s duration for parison pressing (the glass rides down on the plunger~heating cycle).
7 Governing EquationThe heat equation for constant thermo-physical properties:For the 2D axissymmetric case:For the full 3D case:
8 Model Assumptions The glass gob is at a temperature of 1273K. The initial temperature of the plunger is taken to be 773K.Introduce functions Zs(t) to characterize glass motion on the plunger, Zs(t) = 0 when the plunger is not in contact with the glass
9 Boundary ConditionsThe plunger inside surface is subjected to convective cooling to keep the plunger temperature down. However, the heat transfer coefficient is doubled at the tip due to impingement.The outside surface is subjected to both convection and radiation from the glassAll other surfaces are insulated
10 Mesh and SolutionUsing free mesh parameters, 392 elements for 2D axissymmetric model, less than 30s to compute 10 cyclesFor 3D full model, elements with around 7min of computation timeThe mesh was refined at the plunger tip
12 Results (2D Model)The tip of the plunger shows the largest temperature variations through the 10 heating and cooling cycles.The plunger tip heats up more rapidly than the rest of the plunger due to longer glass contact time.
13 SummaryThe COMSOL model has provided useful insight into the plunger temperature variation examined here.Our model uses a simplified glass motion on the plunger surface, We could attempt using motion profiles from the plantWe do not solve for the internal cooling inside the plungerWe have a tool that can provide some qualitative reference for monitoring plunger temperature in the future