Plastic article or earthenware shaping or treating: apparatus – Control means responsive to or actuated by means sensing or... – Feed control of material en route to shaping area
Patent
1995-06-23
1997-08-12
Woo, Jay H.
Plastic article or earthenware shaping or treating: apparatus
Control means responsive to or actuated by means sensing or...
Feed control of material en route to shaping area
264 407, 26427217, 406 28, 406 34, 406 50, 406 83, 4251261, 425172, 425256, 425544, B29C 3106, B29C 4514
Patent
active
056563051
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a system for dosed conveying and selecting of cylindrical pellets for molding apparatus for lead frames.
A chip is mounted onto a central part of a lead frame intended for this purpose and the connecting points of the chip are connected with thin wires to the strip-like leads of the frame. Thereafter the leads and wiring are encapsulated with a protective plastic in a molding apparatus. In such molding apparatus pill or pellet-like units of plastic material are used which become plastic under temperature and pressure and are fed in this state to the lead frame situated in the mould cavity. The environment in which molding takes place is clean, a clean room or clean environment.
Due to the nature of the material the pellets are sources of contamination. This may be the result of crumbling of the pellet whereby dust formation and like contamination occur. It is therefore the object to keep the pellet, and particularly broken off pieces and other contaminating portions, outside the clean environment of the molding apparatus. Only pellets which can be properly processed, that is, without broken off fragments and the like, must be fed to the molding apparatus. On their way from a reservoir to the molding apparatus pellets can be damaged. The handling and transport must therefore take place very carefully.
SUMMARY OF THE INVENTION
The above outlined objectives of the invention are achieved using a system for dosed conveying and selecting of pellets for a molding apparatus for lead frames, comprising: a transport carrier, and device to a mold of a molding apparatus.
With reference to embodiments the invention will be further elucidated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of the system according to the invention,
FIG. 2 is a cut away perspective view of a supply and feed device according to the invention,
FIG. 3 is a perspective view of an infeed and selection device,
FIG. 4 shows an alternative embodiment of the infeed and selection device according to FIG. 3,
FIG. 5 shows a braking device according to the invention in perspective view,
FIG. 5a shows a section along the line Va--Va in FIG. 5,
FIG. 6 is a perspective view of a pellet separating device according to the invention,
FIG. 7 is a dosing device according to the invention in perspective view,
FIG. 8 is a perspective view of a transporting device according to the invention,
FIG. 9 shows a detail IX of FIG. 8, and
FIG. 10 shows an alternative embodiment of the device according to FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The system 1 according to the invention comprises a supply-feed device 2, and infeed and selection device 3, a hose 4, a braking device 5, a pellet separating device 6 and a transporting device 7. A stock of pellets is placed in the supply-feed device 2 and successively conveyed therefrom one by one to the infeed and selection device 3. In the selection device 3 the damaged, i.e. not wholly cylindrical, pellets and fragments are sorted and removed. The accepted pellets are fed one by one to the hose and, using vacuum means, are transported to the braking device 5. The pellets conveyed at relatively high speed are decelerated in the braking device 5 and fed to a buffer forming part of a pellet separating device 6. One by one and synchronously with the action of the transporting device 7 the pellets are then fed to a molding apparatus for encapsulating chip-carrying lead frames.
The components 2 and 3 are placed in a housing (FIG. 1) in order to obtain a separation between a high dust level and a low dust level environment.
The system according to the invention reduces the chance of breakdown and the conveying of pellets not meeting the set requirements, for instance broken pellets, pellets with non-smooth edges which can jam in the transporting paths, including the hose 4, and the like. The system 1 further ensures that the pellets are held as long as possible outside the molding apparatus. This is important since the molding apparatus functions i
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Fico B.V.
Smith Duane S.
Woo Jay H.
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