Mold assembly

A mold assembly includes an upper mold cavity, a base plate, and a flow element. The upper mold cavity defines a primary runner and a plurality of sub-runners on a top surface in communication with the upper mold cavity. A gate is defined in the primary runner for injecting liquefied plastic into the upper mold cavity. The base plate defines an outlet thereon corresponding to the gate for outputting the liquefied plastic. The upper mold cavity and the base plate corporately form a closed cavity therebetween. The flow element is received in the closed cavity and movable between a first position and a second position. In the first position, the flow element is engaged with the primary runner and plurality of sub-runners. In the second position, the flow element is separated with the primary runner and plurality of sub-runners.

BACKGROUND

1. Technical Field

The present disclosure relates to mold assemblies, and particularly to a mold assembly with a flow element.

2. Description of Related Art

Computers have become increasingly popular for general use. Manufacturers are striving to design varieties of portable computers to please users. Therefore, the ornamental design of the enclosure of the computer becomes more and more important for attracting users. Many plastic ornaments, which have different shapes and colors, are attached on the computer enclosure to beautify the computer enclosure. However, for manufacturing these beautiful computer enclosures, the procedure is complex. Firstly, stamping molds to stamp metal plates into required shapes to form a computer chassis are needed. Then, an injection mold to shape the plastic ornaments is needed. Eventually the plastic ornaments are mounted on the computer chassis. In the injection procedure, liquefied plastic is injected into the injection mold by an injection molding machine. However, some of the liquefied plastic flows in the primary runner and a plurality of sub-runners on a top surface of the injection mold, which cools down in the primary runner and plurality of sub-runners later and forms a plurality of plastic scraps. This amounts to waste.

DETAILED DESCRIPTION

Referring toFIGS. 1 and 2, a mold assembly includes an upper mold cavity10, a flow element20, and a base plate30. The mold assembly is used to receive liquefied plastic from an injection molding machine (not shown).

The upper mold cavity10defines a primary runner11and a plurality of sub-runners14on a top surface in communication with the upper mold cavity10. A gate12is defined in the primary runner11for injecting liquefied plastic into the upper mold cavity10. Two accommodating holes13are respectively defined in the upper mold cavity10at two sides of the plurality of sub-runners14.

The flow element20includes two parallel arms21, and a connection arm22perpendicular to the parallel arms21therebetween. The flow element20defines a plurality of protrusions23corresponding to the primary runner11and the plurality of sub-runners14. Each protrusion23defines a groove24in a top surface thereof. The connection arm22defines a channel25in the middle corresponding to the gate12of the upper mold cavity10. A pressing tab26extends outward from the middle of arm21. Each pressing tab26defines a guiding column27thereon which is movably received in the corresponding accommodating holes13. Two springs28are positioned on the guiding columns27.

The base plate30defines an outlet pipe31thereon corresponding to the gate12and the channel25for outputting the liquefied plastic, and two through holes32on two sides of the outlet31corresponding to the two pressing tabs26. The upper mold cavity10and the base plate30cooperatively form a closed cavity therebetween. In this embodiment, the base plate30is positioned on a stamping machine (not shown). The stamping machine (not shown) presses the flow element20upwardly through the through holes32on the base plate30and the pressing tabs26on two sides of the flow element20.

Referring toFIG. 3, in use, the injection molding machine (not shown) injects liquefied plastic into the upper mold cavity10via the gate12until the upper mold cavity10has a certain capacity, such as 80%., The injection molding machine (not shown) stops injecting the liquefied plastic once the capacity is reached. Then the stamping machine (not shown) presses the flow element20upwardly to drive the flow element20to move toward the primary runner11and plurality of sub-runners14. The springs28are elastically deformed. The plurality of protrusions23presses the liquefied plastic in the primary runner11and plurality of sub-runners14through the grooves24. The liquefied plastic quickly flows into the channel25because of the pressure from the primary runner11and plurality of sub-runners14. And very little liquefied plastic remains to cool down in the primary runner11and the plurality of sub-runners14to form plastic scraps. This improves efficiency, saves time, and saves money. Further, the pressure from the primary runner11and plurality of sub-runners14also helps the liquefied plastic to flow out from the outlet31at an even rate. After the liquefied plastic flows from the outlet31, the stamping machine (not shown) is retracted from the base plate30. The springs28elastically return to a normal state and the flow element20moves away from the primary runner11and plurality of sub-runners14.