Mold with high exhaust efficiency

A mold includes a first core and a second core matched with the first core. The first core includes a first die parting surface defining the molding cavity. The second core includes a second die parting surface facing the first die parting surface. A plurality of first exhaust grooves are defined in the first die parting surface. A plurality of transverse second exhaust grooves are defined in the second die parting surface. When the mold is closed, the first core and the second core cooperatively form at least one molding space. The first exhaust grooves are machining marks formed during the machining of the first core. The second exhaust grooves are machining marks formed during the machining of the second core.

BACKGROUND

1. Technical Field

The present disclosure generally relates to molds, and particularly to a mold with better efficiency in preventing or removing gas pockets.

2. Description of Related Art

The ability of a mold to exhaust gas (exhaust efficiency) is an important consideration in mold design. Especially, when molding products with thin walls, the exhaust efficiency of the mold is relatively low, because the die cavity is small and the mold must have the ability to withstand a higher mold locking force for injection of materials at higher speed. Typically a plurality of exhaust grooves is defined in the slide blocks of the mold. A vacuum pump is connected with the exhaust grooves to improve the exhaust efficiency of gas. However, the exhaust efficiency is limited by the vacuum pump, and burrs and fringes on the molding products are easily formed due to the presence of the exhaust grooves.

Therefore, there is room for improvement within the art.

DETAILED DESCRIPTION

Referring toFIG. 1, one embodiment of a mold100for injection molding is shown. The mold100includes a first core10and a second core30matched with the first core10. The mold100further includes other various functional mechanisms, such as a securing mechanism, a heating mechanism, a cooling mechanism, and an ejection mechanism. For simplicity, only the first core10and the second30are described herein in the embodiment.

Referring toFIG. 2, the first core10includes a first die parting surface15. Two molding cavities11are defined symmetrically about a center of the first die parting surface15. A sub-channel13is further defined in the first die parting surface15, between, and communicating with, the two molding cavities11. A plurality of first exhaust grooves151is defined in the first die parting surface15. The first exhaust grooves151are linear and parallel to each other. The first exhaust grooves151are evenly distributed over the whole of the first die parting surface15.

In the illustrated embodiment, a cross-section across each first exhaust groove151is triangular in shape. A depth of each first exhaust groove151across the triangular cross-section thereof is in a range from about 1 micrometer (μm) to about 5 μm. A width of each first exhaust groove151across the base of the triangular cross-section thereof is also in a range from about 1 μm to about 5 μm. The first exhaust grooves151are machining marks formed during the machining of the first core10. A shape and size of each first exhaust groove151can be changed as a function of the machining processes.

The second core30includes a body31and two protrusion portions33formed on the body31. The body31includes a second die parting surface315facing the first die parting surface15of the first core10. A channel311and a sub-channel313are defined in the second die parting surface315. The channel311is defined in a center of second die parting surface315. The sub-channel313is defined between the protrusion portions33and communicates with the channel311, and corresponds to the sub-channel13of the first core10. The two protrusion portions33correspond to the two molding cavities11of the first core10, such that the second core30and the first core10cooperatively form two molding spaces330when the mold100is closed. A plurality of second exhaust grooves3151is defined in the second die parting surface315. The second exhaust grooves3151are linear and parallel to each other. The second exhaust grooves3151are evenly distributed over the whole of the second die parting surface315. An extension direction of the second exhaust grooves3151intersects with an extension direction of the first exhaust grooves151. An intersection angle formed between the second exhaust grooves3151and the first exhaust grooves151is greater than 0 degree, such as 30 degrees, 45 degrees, or 90 degrees.

In the illustrated embodiment, a cross-section across each second exhaust groove3151is triangular in shape. A depth of each second exhaust groove3151across the triangular cross-section thereof is in a range from about 1 μm to about 5 μm. A width of each second exhaust groove3151across the base of the triangular cross-section thereof is in a range from about 1 μm to about 5 μm. The second exhaust grooves3151are machining marks formed during machining of the second core30. If the intersection angle formed between the second exhaust grooves3151and the first exhaust grooves151is 90 degrees, the machining of the first core10and the second core30becomes relatively easy. A shape and size of each second exhaust groove3151can be changed as a function of the machining processes.

In an alternative embodiment, the number of the molding cavities11can be changed as needed, and the number of protrusion portions33will change accordingly. The protrusion portion33can be omitted.

When performing injection molding, the first exhaust grooves151communicate with the second exhaust grooves3151in a criss-cross pattern, forming a plurality of gas vents1510communicating with each other, and the gas vents1510communicate with the molding spaces330. Because the size of each gas vent1510is relatively small, combining with the fact that the quantity of the gas vents1510is relatively great, thus the gases trapped in the molding spaces330are exhausted gently and efficiently. Thus, the incidence or occurrence of burrs and fringes on the molded products caused by the gas exhausting will be reduced. The first exhaust grooves151and the second exhaust grooves3151are formed by machining the first core10and the second core30, so that additional costs of machining the exhaust grooves can be omitted, and the cost of the mold100is relatively low.