Coating apparatus – Control means responsive to a randomly occurring sensed... – Responsive to attribute – absence or presence of work
Reexamination Certificate
1999-04-02
2001-06-26
Crispino, Richard (Department: 1734)
Coating apparatus
Control means responsive to a randomly occurring sensed...
Responsive to attribute, absence or presence of work
C118S679000, C118S690000, C118S308000
Reexamination Certificate
active
06251185
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to a system for delivering chopped glass fibers to a preform screen where desired with very little loss to form preforms used to make reinforced polyester parts.
BACKGROUND OF THE INVENTION
Chopped glass fiber random mats or preforms are commonly used to make reinforced polyester parts. A preform generally consists of approximately 90 to 95% chopped fiberglass strands bonded together with approximately 5 to 10% resin binder. These preforms are then placed in a mold located within a compression press and resin paste is applied to mold the part into the final desired shape.
Preforms are formed into substantially the exact shape of the desired part using a preform screen of perforated material the exact shape of the male mold. The preform screen is mounted over a fan inlet which draws air through the preform screen to capture chopped glass fibers on the screen and hold them in place while a binder emulsion is sprayed onto the fibers and cured to hold the fibers in the proper shape during compression molding of the part.
The current system used to deliver chopped fiberglass strands to the preform screen includes a stationary chopper driven by an electric motor to chop a series of continuous fiberglass strands, called glass roving, into lengths for example of one-half inch to four inches. The cut glass fibers drop through a feed funnel into an air stream from a stationary blower which blows the glass fibers toward the preform screen through a flexible delivery tube that is moved manually relative to the preform screen.
While this chopper delivery system has been used effectively for many years, a major disadvantage is that the stationary chopper blower unit must be mounted several feet from the preform screen to accommodate the size and shape of the preform. The greater the distance between the chopper blower unit and the preform screen, the longer the distance the chopped glass fibers must be carried through the air to the screen. As this distance increases, a certain amount of the fiberglass strands fall out of the air stream and are lost. Also, with a longer flexible tube, the greater the risk that the tube will bend or kink, causing the fiberglass strands to clump up and drop out by gravity or causing the tube itself to clog up.
SUMMARY OF THE INVENTION
The present invention provides a system for placing the chopped fiberglass strands onto the preform screen where desired with very little loss.
In accordance with one aspect of the invention, the system includes a relatively light-weight chopper/feeder unit mounted on a robot arm that places the output from the chopper/feeder unit a relatively short distance (e.g., only about a foot) from the preform screen for robotically directing the chopped fiberglass strands onto the preform screen.
In accordance with another aspect of the invention, one or more air amplifiers are mounted on the chopper/feeder unit to provide an air stream within the chopper/feeder box to carry the chopped fiberglass strands from the chopper/feeder box to the preform screen.
In accordance with another aspect of the invention, the air amplifiers generate enough velocity and volume of air within the chopper/feeder box to carry the chopped fiberglass strands away from the chopper/feeder cutter without bunching and clogging.
In accordance with another aspect of the invention, the spacing between the inside of the chopper/feeder box and the cutter is controlled to generate adequate air velocity within the box without restricting air flow from the input side of the box to the discharge side.
In accordance with another aspect of the invention, a relatively small variable speed motor is used to drive the cutter.
In accordance with another aspect of the invention, a hydraulic motor is used to drive the cutter, controlled by a servo valve and electronic sensor on the chopper rolls integrated with a programmable logic control unit (PLC) for controlling the cutter speed and thus the output of chopped fiberglass strands for controlling the distribution of the chopped fiberglass strands where desired on the preform screen.
These and other aspects, objects, advantages and features of the present invention will become apparent as the following description proceeds.
To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which the principles of the invention may be employed.
REFERENCES:
patent: 3491443 (1970-01-01), Fram
patent: 3984054 (1976-10-01), Frochaux
patent: 4088469 (1978-05-01), Schaefer
patent: 5092522 (1992-03-01), Dykmans
patent: 5093059 (1992-03-01), Nathoo et al.
patent: 5645884 (1997-07-01), Harlow, Jr. et al.
Hutchinson Kenneth T.
Mollman Robert E.
Morrison Richard S.
Crispino Richard
Molded Fiber Glass Companies
Renner , Otto, Boisselle & Sklar, LLP
Tadesse Yewebdar T
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