Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Reexamination Certificate
1999-05-18
2001-06-12
Heitbrink, Tim (Department: 1722)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
C425S564000, C425S566000
Reexamination Certificate
active
06245279
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to hot runner edge gating nozzle for molding thin flat articles, particularly smart cards.
Flat parts of constant cross section thickness are typically gated at one end so that the molten plastic material, such as a plastic resin, flows the longest path to fill the part. In this way, molded in stresses which cause warpage are avoided. Such parts preferably are molded using an edge gate rather than a pin gate into one of the larger surfaces, because injecting the plastic material perpendicularly to the flow direction for filling can cause part blemishes, such as jetting, and warpage. Injecting the plastic material aligned with the flow direction for filling minimizes these problems.
Smart cards are wallet size plastic cards containing an embedded computer chip. The chip is an integrated circuit that can be preprogrammed to interact with sensors and readers that the card may come into contact with. Injection molding smart cards is becoming the preferred method of manufacture. The paper “Why Automation for Chip Cards”, by Truckenbrod summarizes the current state of the smart card art. When using an injection molding technique, it is important to design the mold cavity gates so that flat warp free cards are molded without any gate vestige that may cause injury when the cards are handled.
Published European Patent Application No. 0 800 908 to Herbst shows an edge gating technique for molding articles such as smart cards.
FIGS. 6 and 7
in this document show a sleeve that is advanced to sever the gate. If this sleeve is cylindrical, then the severed edge of the part will not be linear but rather circular. This technique is not well suited for making rectangular style cards.
Published European Patent Application 0 800 907 to Manner shows a conventional hot runner valve gate having a melt passage cut into the valve stem that feeds plastic resin transversely into the side of a mold cavity—in effect an edge gate. Again, the valve stem is cylindrical and will not produce a flat vestige free surface on the flat edge of a rectangular part.
U.S. Pat. No. 5,460,509 to Sawafuji shows a cold runner edge gating system with opposed knives that sever the frozen runner. U.S. Pat. No. 2,890,488 to Gemberling shows a movable hot runner nozzle that severs the gate after filling the cavity; however, pin gating into a flat surface is only shown.
Co-pending U.S. patent application No. 09/036,132 now U.S. Pat. No. 6,161,899 shows a slide gate approach for closing a hot runner pin gate.
None of these prior art documents illustrates how to hot runner edge gate a rectangular shaped article along a flat side to make a vestige free gate mark.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an apparatus and a method for manufacturing a rectangular shaped article which is substantially vestige free along a flat side.
It is a further object of the present invention to provide an apparatus and method as above which has particular utility in the manufacture of smart cards.
The foregoing objects are attained by the apparatus and the method of the present invention.
The present invention relates to an apparatus for manufacturing a substantially flat article, such as a smart card, having substantially flat edges. The apparatus preferably includes a mold for forming the substantially flat article, which mold includes an inlet gate for allowing molten plastic material to flow into a cavity space defined by the mold. The apparatus further includes a source of molten plastic material, a passageway communicating with the inlet gate and the source of molten plastic material, and a blade or pin for pushing residual plastic material in the passageway into the cavity space formed so as to form a side edge for the substantially flat article having substantially no gate vestige.
The method in accordance with the present invention broadly comprises the steps of providing a mold means for forming a substantially flat article, such as a smart card, having substantially flat edges, the mold means including a mold cavity and an edge gate for allowing molten plastic material to flow into a cavity space formed by the mold means, providing a source of molten plastic material having an outlet and a passageway between the outlet and the edge gate, creating a flow of hot molten plastic material from the source to the edge gate, substantially filling the cavity space with the hot molten plastic material, stopping flow of the molten plastic material into the passageway, and pushing any residual plastic material in the passageway into the cavity space so as to form a substantially vestige free side wall.
Other details of the apparatus and process of the present invention, as well as other objects and advantages attendant thereto, are set forth in the following description and the accompanying drawings in which like reference numerals depict like elements.
REFERENCES:
patent: 2890488 (1959-06-01), Gemberling
patent: 3936261 (1976-02-01), Jones et al.
patent: 3995981 (1976-12-01), Fries
patent: 5460509 (1995-10-01), Sawafuji et al.
patent: 0791448 (1997-08-01), None
patent: 0800907 (1997-10-01), None
patent: 0800908 (1997-10-01), None
patent: 2152952 (1973-04-01), None
patent: 7-068601 (1995-03-01), None
patent: 8-085142 (1996-04-01), None
patent: 9-066542 (1997-03-01), None
“Why Automation for Chip Cards?”, By Willi Truckenbrod, pp. 4-6.
Bachman & LaPointe P.C.
Heitbrink Tim
Husky Injection Molding Systems Ltd.
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