Timpul de răcire al pieselor turnate prin injecție

Calculul timpului de răcire al pieselor turnate prin injecție din plastic.

Ca mașină de turnat prin injecție,în injection production, timpul de răcire a pieselor turnate prin injecție din plastic reprezintă aproximativ 80% a întregului ciclu de producție prin injecție. Răcirea slabă duce adesea la deformarea produsului sau la defecte de suprafață, care afectează stabilitatea dimensională a produsului. Aranjament rezonabil al injecției, holding pressure and cooling time can improve product quality and productivity.

The cooling time of the part usually refers to the period from when the plastic melt is filled with the injection mold cavity to when the part can be opened and taken out. The time standard for opening the mold to take out the parts is usually based on the fact that the parts have been fully cured, have a certain strength and rigidity, and will not be deformed or cracked when the mold is ejected.

Even if the same type of plastic is used for molding, its cooling time varies with the thickness of the wall, the temperature of the molten plastic, the demolding temperature of the molded part, and the temperature of the injection mold.

The formula to calculate the cooling time 100% correctly in all situations has not yet been published, but only formulas that can be calculated on the basis of appropriate assumptions. The calculation formula also differs depending on the definition of the cooling time.
In prezent, the following three standards are usually used as the reference basis for cooling time:

①The temperature of the center layer of the thickest part of the plastic injection molded part, and the time required to cool to below the thermal deformation temperature of the plastic;

②The average temperature in the section of the plastic injection molded parts, and the time required to cool down to the mold temperature of the specified product;

③The temperature of the center layer of the thickest part of the crystalline plastic molding wall is the time required to cool below its melting point, sau timpul necesar pentru a atinge procentul specificat de cristalizare.

When solving the formula, se fac în general următoarele ipoteze:

①The plastic is injected into the matriță de injecție, and the heat is transferred to the injection mold to be cooled;

②The plastic in the molding cavity is in close contact with the mold cavity and will not be separated due to cooling shrinkage. There is no resistance to the heat transfer and flow between the melt and the mold wall.

The temperature of the melt becomes the same when it contacts the mold wall. Acesta este, when the plastic is filled into the mold cavity, the surface temperature of the part is equal to the mold wall temperature;

③During the cooling process of plastic injection molded parts, the temperature of the surface of the injection mold cavity is always uniform;

④The degree of heat conduction on the surface of the injection mold is certain; (the melt filling process is regarded as an isothermal process, and the material temperature is uniform)

⑤The influence of the orientation and thermal stress of the plastic on the deformation of the part can be ignored, and the size of the part has no effect on the solidification temperature.

Dacă aveți întrebări despre turnare prin injecție ,va rog nu ezitati sa intrebati Echipa FLYSE,vă vom oferi cel mai bun serviciu!