Plastic and nonmetallic article shaping or treating: processes – With severing – removing material from preform mechanically,...
Reexamination Certificate
1999-03-29
2001-02-06
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With severing, removing material from preform mechanically,...
C264S161000, C264S328100, C475S152000, C475S152000, C029S418000
Reexamination Certificate
active
06183678
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention concerns manufacturing of molded plastic glazing panels, particularly curved glazing panels used in automotive vehicles.
The use of molded plastic glazing panels for the windows of automotive vehicles offers many advantages, such as reduced weight, superior resistance to fracture and/or dislodgment in the case of accidents, and greater freedom in vehicle styling due to the ease of forming glazing panels in any desired shape.
These advantages have not heretofore been realized on a large scale due to the difficulty in matching the optical clarity and scratch resistance of conventional glass panels. Such plastic panels must be resistant to obscuration due to UV radiation exposure, and must also block UV transmission to prevent deterioration of interior trim surfaces and fabric materials by UV radiation.
Polycarbonate has been widely proposed for this application, and the technology for hard coating this plastic has been developed which allows for the manufacture of UV and scratch resistant plastic glazing panels. This technology involves coating the panels, as by dipping the panels in tanks of liquid coating material and subsequent curing of the coating in an oven. Other coating processing steps have been developed as well for this application, such as a plasma coating.
In the automotive industry, any defect in a glazing panel which creates a visible optical flaw during the handling and processing would result in rejection of the part. Accordingly, handling and processing must be carried out in such a way as to minimize creating optical flaws.
The manufacture of automotive components is done on a vast scale in a very competitive environment, and thus, the processing of glazing panels must be carried out highly efficiently while still producing quality parts. There is a high probability of producing defective parts while handling the panels during dipping into a tank of liquid coating, as drips or the running of the liquid coating material onto the glazing may result in a visible flaw.
At the same time, the distinct curved shape of the glazing panels makes compact racking of the panels difficult. Any bumping of the panels as they are racked may also create scratches or other surface defects necessitating rejection of the part.
Accordingly, it is an object of the present invention to provide a method for handling of molded plastic glazing panels during processing steps which minimizes the incidence of optical flaws, yet allows large numbers of the panels to be efficiently handled during processing, and compactly stacked together in a vertical array.
SUMMARY OF THE INVENTION
The above object as well as others which will be understood upon a reading of the following specification and claims are achieved by a handling process in which one or more handling tabs are molded integrally with the transparent plastic glazing panel, projecting in an outward direction from the perimeter of the panel.
The tab or tabs each have a pair of side-by-side spaced apart engagement features engaged by mating features on a support structure so as to resist side-to-side and rotational movement of the panel. These engagement features may be comprised of a pair of bosses, each formed with a hole adapted to receive one of a pair of holder pins fixed to the support structure. The bosses may be stiffened with gussets extending towards the glazing panel, but blending into the tab short of the panel perimeter. The gussets promote controlled liquid run off to prevent puddling and dripping, and stiffen the bosses to resist front to rear movement of the panel.
As noted, the spaced apart bosses eliminate side to side rotation of the panel while the bosses and gussets provide stiffening structure able to resist front to rear movement of the panel. The tab enables holding the panel so as to resist any buoyancy induced tendency for movement of the panel during tank dipping, and allows the panel to be held in a tilted position for compact horizontal stacking of curved panels on racks, conveyors, hanger brackets, or supporting structure on other transfer devices used to handle the panels.
A raised ridge extending about each hole on the rear face of the tab minimizes the tendency of coating liquid to be retained between the rear tab face and an adjacent support surface against which the tab is abutted in hanging the panel.
The bosses have a generous draft taper to facilitate removal from the mold, and the holes are also similarly tapered. A series of inversely tapered ribs arranged about each hole interior may also be used to allow engagement with a constant diameter hanger pins.
The pins may also be tapered and formed with a larger diameter end, creating a step which serves to capture the tab once emplaced on the pins, preventing unintended movement off the pins as may result from vibrations or bumping of the support structure.
The tab engagement features may be configured identically for each glazing panel configuration such as to allow standardized fixturing and efficient use of automated handling equipment such as robots. That is, variations of the support structure can be used with a “universal” tab, or different tab configurations could be used on the same or different parts. A J-hook or bracket extension can be utilized to lower the position of the panel on the support structure.
At the conclusion of the panel processing, the tabs are trimmed off, with a slight step at the intersection of the tab and panel facilitating cut off.
REFERENCES:
patent: 4695420 (1987-09-01), Grawey et al.
patent: 5401453 (1995-03-01), Moretz et al.
patent: 5428879 (1995-07-01), Miller et al.
Hovatter Thomas
Katsamberis Dimitris
Kusuma David
Matsco Mark M.
Benefiel John R.
Exatec, LLC.
Lee Edmund H.
Silbaugh Jan H.
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