Sole Structure Molding With Closed-Loop Pressure Control
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Solution Overview
Problem
Injection molding processes for polymer products, such as shoe soles, suffer from inconsistencies due to fluctuations in pressure and temperature, leading to variations in cell size, expansion ratio, and mechanical properties.
Innovation Solution
Implementing a closed pressure sensing loop to maintain a consistent nozzle pressure profile and temperature control of the molten polymeric material during the injection process, using a system with pressure and temperature feedback mechanisms to adjust the flow rate and temperature of the material into the mold cavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If automation is used in injection molding, then productivity is improved, but manufacturing precision deteriorates due to pressure and temperature variations
Solution Approach 1:
The patent implements feedback control by monitoring actual nozzle pressure and melt temperature during injection molding, comparing these values to target profiles, and automatically adjusting injection parameters to compensate for deviations. This closed-loop control system maintains manufacturing precision while preserving automated productivity.
Solution Approach 2:
The patent dynamically adjusts injection parameters including injection rate, holding pressure, and melt temperature based on real-time process conditions. By changing these parameters adaptively rather than using fixed automated settings, the system maintains consistent cell size and expansion ratio despite variations in material or environmental conditions.
2Productivity
If injection rate is increased to improve productivity, then manufacturing precision deteriorates due to pressure fluctuations
Solution Approach 1:
The patent transitions from static injection rate settings to dynamic rate adjustment based on real-time pressure feedback. The injection rate is continuously modified during the molding cycle to maintain target nozzle pressure, allowing high productivity while preventing pressure-induced variations in foam structure.
Solution Approach 2:
The system uses pressure sensors to monitor nozzle pressure continuously and feeds this information back to the injection control system. This enables automatic adjustment of injection rate to compensate for pressure deviations, maintaining both speed and precision.
3Manufacturing precision
If temperature control is added to maintain precision, then device complexity increases
Solution Approach 1:
The patent integrates temperature control functions into the existing injection molding system rather than adding separate dedicated equipment. The control system performs multiple functions including pressure monitoring, temperature control, and injection rate adjustment, reducing overall system complexity despite enhanced precision capabilities.
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 repeatable and uniform physical parameters, reducing variability between injection molded products and improving control over dimensions and properties.
Implementation Method 1
A nozzle of the injecting device may be adapted with a pressure sensor, where the pressure sensor may be included in a pressure feedback loop that relays a pressure of the nozzle to a controller
Implementation Method 2
A barrel of the injecting device, configured to store the polymeric material and including heating devices to heat the barrel
Implementation Method 3
The barrel may be adapted with a temperature sensor to detect a temperature of the barrel. The temperature sensor may be included in a temperature feedback loop that relays the temperature of the barrel to the controller
Data Source
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AI summary
A molding system and a method for forming a sole structure are provided. The method includes flowing a molten polymeric material into a mold from an upstream device, receiving the molten polymeric material in a cavity of the mold, and maintaining a repeatable, uniform pressure profile as the molten polymeric material is delivered into the mold.