How to design the cooling system of rice cooker shell mold parts to improve molding efficiency?
Release Time : 2025-09-17
The cooling system design for rice cooker shell mold components must be tailored to the mold's structural characteristics, part molding requirements, and process stability. By optimizing the water channel layout, controlling the cooling medium's state, and matching the mold's motion mechanism, molding efficiency can be significantly improved while ensuring product quality. Rice cooker shells are often thin-walled, but localized features such as ribs and clips can easily lead to uneven heat distribution. Therefore, the cooling system must balance overall uniformity with localized targeting to avoid defects such as sink marks and warping caused by large temperature differences.
The cooling water channel layout of the mold component must be tailored to the geometry of the rice cooker shell. For circular or elliptical shells, the water channels should be distributed in a circular or spiral pattern along the cavity contour to ensure uniform cooling coverage across the entire cavity surface. For areas with ribs, branch water channels should be added at the rib base to quickly remove heat through forced convection, preventing localized overheating that can cause surface dents or internal stress concentrations in the part. Furthermore, the water channel spacing should be adjusted based on the mold material's thermal conductivity, typically maintaining a consistent distance from the cavity surface to prevent part deformation caused by uneven cooling.
The flow pattern of the cooling medium directly impacts heat transfer efficiency. Traditional laminar flow has a low heat transfer coefficient and can easily lead to uneven cooling, while turbulent flow can significantly improve heat transfer efficiency. During design, the cooling water should maintain turbulent flow within the mold by adjusting the water channel diameter, flow velocity, and Reynolds number. For example, a parallel water channel system can be used to prioritize low-temperature water flow into high-temperature areas (such as near the gate), with the outlet located in the low-temperature area. This creates a "high-temperature zone-first cooling" circulation path, shortening overall cooling time. Furthermore, the cooling medium must be kept clean to prevent scale from clogging the water channels and reducing heat transfer efficiency.
The motion mechanisms of mold components constrain cooling system design. Common mold components such as lifters and sliders must maintain a safe distance from the cooling water channels to avoid interference and leakage. For example, a rotary joint can be used inside the slider to connect the water channels, ensuring a continuous cooling path during slider movement. For lifters, densely arranged thin water channels, positioned away from the ejector pins, prevent thermal deformation that could affect product precision. At the same time, the mold's parting surface, gate location, and other factors must also be considered in the cooling system design to ensure that heat-concentrated areas are cooled preferentially.
The cooling medium parameters for mold components must be dynamically adjusted based on material properties. Rice cooker shells commonly use materials such as PP and ABS, whose crystallization characteristics or heat distortion temperatures dictate different cooling rates. For example, PP needs to avoid rapid cooling, which can lead to embrittlement; the cooling medium temperature should be controlled between 20-30°C. ABS, on the other hand, requires a higher cooling rate to prevent surface stickiness, so the cooling medium temperature can be appropriately lowered. Furthermore, the cooling medium pressure must be stable to avoid pressure fluctuations that can lead to uneven water flow and affect cooling efficiency.
The cooling system for mold components must be designed in coordination with the ejection mechanism. During ejection, the contact area between the plastic part and the mold cavity is reduced. Insufficient cooling can easily lead to part deformation. Therefore, separate cooling channels should be arranged in the ejection area to ensure that the part is fully cooled and solidified before ejection. For example, a circular water channel can be added around the ejector pin, or the holding time before ejection can be extended to ensure sufficient heat transfer to the cooling medium, reducing the risk of deformation during ejection.
Validating the cooling system for mold components requires a combination of simulation and trial mold adjustments. Using mold flow analysis software such as Moldflow, simulate the temperature distribution, focusing on identifying "hot spots" (areas with significant temperature differences). If so, increase the number of cooling channels or adjust the layout. Simulate cooling time and warpage to optimize parameters in advance. During the trial mold phase, observe for defects in the molded part. If sink marks are present, increase the number of cooling channels or shorten the cooling time in the corresponding area. If the part is deformed, adjust the cooling channel layout to balance the mold temperature. Furthermore, use a flow meter to monitor the flow rate in each branch to ensure uniformity.
The cooling system design for rice cooker shell mold components must balance structural compatibility, heat transfer efficiency, and material properties. Using conformal cooling channels, turbulence control, parameter optimization, and collaborative design can significantly improve molding efficiency, shorten cooling time, and reduce product defect rates. A well-designed cooling system not only improves production efficiency but also extends mold life, ensuring stable, high-volume production of rice cooker shells.
