Localized and delayed response of mold temperature to cooling channel activation in low-pressure die casting of aluminum alloy wheels

Low-pressure die-casting is the main forming method for aluminum alloy wheels, and the response characteristics of permanent mold temperature to the activation and deactivation of cooling channels are an important basis for the design and control of the cooling system in the low-pressure die-casting of aluminum alloy wheels. In this study, based on actual continuous production cycles, automatic temperature acquisition and differential temperature curve analysis were employed to investigate the response of the mold temperature at multiple measurement locations to the operation of each cooling channel. The results reveal that the cooling effect of each channel is both highly localized and delayed. A cooling channel influences only the mold temperature in its immediate vicinity, and the cooling effect at these near positions always appears after channel activation. The delay is more pronounced when the cooling medium is water; the heat transfer delay, which increases with the distance between the location of direct cooling-medium action and the thermocouple, is the dominant factor, while the flow transit delay is a secondary factor. At measurement locations distant from the cooling channel, the shape of the temperature curve remains largely unchanged, and the temperature differential curves show a high degree of overlap. A harmonic analysis of one-dimensional transient heat conduction further reveals that these characteristics originate from the exponential spatial decay and the phase lag of the temperature oscillation induced by the cyclic operation of the cooling channel. These findings are expected to provide theoretical guidance for the design and control of cooling systems for low-pressure die-casting molds of aluminum alloy wheels.