| 摘要 |
A method for cooling a plunger tip of a die-casting machine for maintaining a proper clearance between a plunger tip and a shot sleeve. A proper hydraulic pressure in an injection cylinder is determined at which no galling occurs in the shot sleeve. Hydraulic pressure in the injection cylinder is measured several times in a state where no molten metal exists in the shot sleeve. For example, measured is the hydraulic pressure in the injection cylinder at the time of return stroke of the plunger tip immediately after injecting operation. Average hydraulic pressure is computed based on the plurality of measured hydraulic pressure. The average hydraulic pressure is compared with the proper hydraulic pressure. If the former is greater than the latter, clearance between the plunger tip and the shot sleeve is deemed to be too small. Thus, supply amount of cooling liquid to the plunger tip is increased to reduce a diameter of the plunger tip.
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