Plastic and nonmetallic article shaping or treating: processes – Orienting or aligning solid particles in fluent matrix material
Patent
1998-11-28
2000-08-22
Silbaugh, Jan H.
Plastic and nonmetallic article shaping or treating: processes
Orienting or aligning solid particles in fluent matrix material
26432812, B29C 1700
Patent
active
061067520
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention pertains to the art of methods and apparatuses for producing short fiber/rubber composite articles through injection molding and to those composite articles so produced, and more specifically to methods and apparatuses for orienting the reinforcing fibers of a composite article in a predetermined direction.
BACKGROUND ART
Generally, composite articles formed of an elastomeric base material and reinforcing fibers are common in the art. The reinforcing fibers impart improved mechanical properties, such as abrasion resistance, tensile strength, compression resistance, and the like to the composite article. The fiber distribution and orientation are important factors which affect such properties. Controlling fiber orientation, therefore, is an important consideration in order to provide a composite article having the desired mechanical properties.
There are known techniques for orienting reinforcing fibers in an elastomeric material. However, in many processes the fibers are generally oriented in a direction consistent with and parallel to the initial material flow direction. A problem encountered in the art relates to orienting reinforcing fibers in a composite article in a direction which differs from the material flow and especially in a direction perpendicular thereto.
One method proposed to orient fibers in a composite article in a direction which varies from the material flow is disclosed in U.S. Pat. No. 5,156,907 wherein a heated mixture of molding compound (glass) and fibers (carbon) is injected through an elongated injection port into a die. The injection port has a thickness which is purported to be between 30%-70% of the die thickness. The optimum fiber length is 0.5 inches (1.27 cm) for the particular carbon fiber/glass matrix utilized.
U.S. Pat. No. 5,281,380 discloses a fiber reinforced elastic sheet in which staples are oriented in the vertical direction of the sheet. Staple material, such as Nylon 66, is mixed into thermoplastic material and extruded through a molding die. The molding die includes a weir portion which is said to initially orients the fibers in the flow direction. Downstream from the weir portion is a flow passage which has a dimension at least twice that of the weir portion. After passing through the weir portion, the flow direction is changed, thereby changing the fiber be further processed for an intended application.
The present invention provides methods and apparatuses for orienting short fibers (fibers having a length of 0.1 microns to 10.sup.3 microns) in a composite article formed by injection molding a molding compound comprising a fiber/elastomeric material blend. The fibers utilized are known as "short fibers" in the art and have a length considerably shorter than the 0.5 inch (1.2 cm) length of short fibers of the U.S. Pat. No. 5,156,907 patent discussed in above.
DISCLOSURE OF INVENTION
The present invention is directed to methods and apparatuses for forming composite articles comprising reinforcing fibers. More particularly, the present invention is directed to methods and apparatuses for directing fiber orientation in composite articles formed by injection molding a molding compound composed of short fibers and elastomeric material.
According to one aspect of the present invention, a method for producing a fiber reinforced composite article by curing a molding compound after injecting the molding compound into a mold cavity of a mold, the molding compound comprising elastomeric material and reinforcing fibers, the fibers having a length from 0.1 microns to 10.sup.3 microns is provided. The method is characterized by the steps of: gate, the first inlet gate having an associated length l1, width w1, and thickness t1, and wherein a majority of the reinforcing fibers contained in the first portion are oriented parallel to the initial injection direction, X; and, region of said mold cavity, the first region of the mold cavity having a dimension, T1, parallel to t1, wherein T1 is greater than or equal to 10t1, the first portion fo
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Chang Ching-Chian
Shaw Cheng
Vogliano Robert Henry
Emerson Roger D
Lee Dae Young
Silbaugh Jan H.
The Goodyear Tire & Rubber Company
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