Apparatus and methods for curing an adhesive promoter on a windshield

A method for curing an adhesive promoter onto glass. An adhesive promoter having a solvent carrier is first applied to the glass, and the treated glass is introduced into a first chamber maintaining an environment with temperature between approximately 93.degree. C. and 127.degree. C. (200.degree. F. and 260.degree. F.) to flash off the adhesive promoter's solvent carrier. The glass is then introduced into a second chamber maintaining an environment for heating and humidifying the glass with temperature between approximately 65.degree. C. and 93.degree. C. (150.degree. F. and 200.degree. F.) and humidity between approximately 80 and 90 percent for hydrolysis to promote the formation of a laminate on the edge of the glass. Thereafter, the glass is introduced into a third chamber maintaining an environment with temperature between approximately 93.degree. C. and 121.degree. C. (200.degree. F. and 250.degree. F.) to dry the glass and evaporate the water from the laminate. The glass is retained in each of the chambers for a period of approximately 3 to 4 minutes.

BACKGROUND 
1. Field of the Invention 
This invention relates to windshield encapsulation and, more particularly, 
to apparatus and methods for curing an adhesive promoter on a windshield 
in preparation for encapsulation. 
2. The Background Art 
Traditionally, the methods used to encapsulate a windshield for 
introduction into an automobile involve adding an adhesive sealant and a 
trim to the outside edges of a windshield, while the windshield is still 
on the assembly line. More particularly, the prior art offered methods 
consisting of the addition of an adhesive sealant to the windshield, an 
application of a decorative trim to the peripheral edges of the glass, and 
a plurality of mechanical fasteners or metal clips connecting the 
windshield to the vehicle frame to maintain the windshield within the 
channel-groove of the automobile. However, these traditional methods are 
characterized as being time consuming and labor intensive. 
To improve the existing practices within the industry, a process of 
employing conventional gasket compression and injection molding techniques 
was introduced. However, because of the types of materials used in molding 
the gaskets, the conventional compression and injection molding techniques 
were later found to lack the proper adhesion qualities between the gasket 
and the metal body parts, as well as the gasket adhering to the peripheral 
edges of the windshield. The deficiency in proper adhesion between the 
windshield and the channel-groove of the automobile frame resulted in 
water leaks, wind noise, and other related problems. Thus, to accommodate 
the compression and injection molding techniques and the problems of 
insufficient adhesion, additional mechanical fasteners were needed to 
secure the windshield to the body panels. 
Because of the disadvantages of improper adhesion, an improvement in prior 
art methods followed. A unitary windshield assembly consisting of a sheet 
of glass, an adjoining frame, and a casing or gasket of molded material, 
such as polyvinylchloride or urethane, was introduced to the industry. The 
unitary windshield became recognized as a significant improvement over the 
existing prior art methods because the windshield assemblies arrive at the 
point of installation, and are ready to be incorporated into the 
automobile. 
These unitary window assemblies are typically made by encapsulating the 
edge of the windshield with a urethane gasket to which a frame may be 
attached. Whereby, the sheet of glass and the frame are retained 
collectively together. A number of fasteners may then be provided at 
spaced locations along the frame, such that the entire assembly may be 
guided into precise alignment over the channel-groove of the vehicle 
frame. 
Several steps, however, are dictated before the urethane or 
polyvinylchloride gasket can be secured to the windshield. First, an 
adhesive promoter substance should be administered to the glass surface 
and then permitted to cure before the gasket is applied. Currently, the 
industry typically applies an adhesive promoter to the windshield, and 
stores the windshield in a high humidity setting for a period up to 24 
hours to allow the windshield to cure before the gasket molding can be 
applied thereto. 
Because the adhesive promoter must be allowed to completely cure before 
applying the urethane gasket, there are significant disadvantages in the 
existing curing practices. First and foremost, the present curing 
practices prove to be severely time consuming. Whereby, a windshield is 
customarily cured for a period of 24 hours after applying an adhesive 
promoter delineating a substantial period of time invested before the 
windshield is ready for encapsulation and introduction into the 
automobile. 
An additional disadvantage involves the costs incurred for having to store 
the windshields in relatively large, high humidity rooms to cure the 
adhesion promoter properly. The size of the high humidity storage rooms 
become necessary to achieve any substantial output of cured windshields 
ready for encapsulation within a timely fashion. 
Consequently, the current practices in the industry to cure the windshield 
assemblies for encapsulation are considerably labor intensive, requiring 
more than one employee to maneuver around the large racks of windshields 
undergoing the curing process. Unfortunately, the methods of curing large 
quantities of windshields at each setting, tend to produce a substantial 
number of defective products. 
Considering all these factors, the known prior art methods involved in 
curing an adhesive promoter onto a windshield for encapsulation by a 
molded gasket before introduction into the automobile involve large 
investments of time, resources and manpower to produce quality products. 
BRIEF SUMMARY AND OBJECTS OF THE INVENTION 
In view of the foregoing, a primary object of the present invention is to 
provide a windshield curing apparatus and method for curing an adhesive 
promoter on a windshield in a shorter period of time. 
It is also an object of the present invention to provide a windshield 
curing apparatus and method for curing an adhesive promoter on a 
windshield which does not involve high storage costs. 
Further, it is an object of the present invention to provide a windshield 
curing apparatus and method for curing an adhesive promoter on a 
windshield which is not labor intensive. 
It is still further an object of the present invention to provide a 
windshield curing apparatus and method for curing an adhesive promoter on 
a windshield which produces a more consistent product with fewer defects. 
Consistent with the foregoing objects, and in accordance with the invention 
as embodied and broadly described herein, a windshield curing apparatus is 
disclosed in one embodiment of the present invention as including a main 
body separated by divider walls into four chambers which are rotated 
through four distinct environments. 
In the main body, the divider walls extend radially from an axle along the 
center axis of the main body dividing the main body into four chambers of 
equal size. A direct current variable speed motor causes the axle to 
rotate substantially 90 degrees at a time. Thereby, the four chambers are 
rotated through the four distinct environments. In addition, the motor is 
controlled by double palm buttons attached at a distance apart on the 
exterior of the main body. 
Each chamber includes a windshield holder comprising at least two posts 
extending radially from the axle separated by a suitable distance. One end 
of the posts is attached to the axle and a vacuum cup is attached to the 
opposite end of each post. An opening, large enough for a windshield to be 
placed in the curing apparatus, is provided in the main body coincident 
with the first environment for loading and unloading the windshields. 
Heater units and a steam generator are attached to the main body of the 
windshield curing apparatus in different locations to control separate and 
distinct environments in three separate chambers. A second environment is 
maintained by a heater unit establishing a temperature between 200.degree. 
F. and 260.degree. F. to flash off the adhesive promoter's toluene 
carrier. A third environment is maintained at a temperature between 
150.degree. F. and 200.degree. F. and at a humidity between 80 and 90 
percent for hydrolysis by a separate heater unit and a steam generator. 
Finally, the fourth environment is maintained at a temperature between 
200.degree. F. and 250.degree. F. to dry the windshield and to evaporate 
water from the laminate by another individual heater unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
It will be readily understood that the components of the present invention, 
as generally described and illustrated in the Figures herein, could be 
arranged and designed in a wide variety of different configurations. Thus, 
the following more detailed description of the embodiments of the 
apparatus and methods of the present invention, as represented in FIGS. 1 
through 3, is not intended to limit the scope of the invention, as 
claimed, but it is merely representative of the presently preferred 
embodiments of the invention. 
The presently preferred embodiments of the invention will be best 
understood by reference to the drawings, wherein like parts are designated 
by like numerals throughout. 
The windshield curing apparatus of the present invention, generally 
designated at 10, is shown in its entirety in FIG. 1. As shown, the 
windshield curing apparatus 10 comprises a main body 20 being a 
substantially hollow, closed container generally cylindrical in shape. The 
main body 20 has a back end 22 and a front end 24 positioned on opposing 
sides of the windshield curing apparatus 10. 
An opening 26, large enough to allow a windshield 11 to be inserted 
therein, is provided on a side of the windshield curing apparatus 10 and 
extends between the back end 22 and the front end 24 of the main body 20. 
The opening 26 of the windshield curing apparatus 10 may be substantially 
rectangular in shape, however, it will be readily appreciated that other 
shapes or configurations are feasible. 
An axle 36 running linear along the center axis of the main body 20, 
coexists between the back end 22 and the front end 24 of the windshield 
curing apparatus 10. Associated with the axle 36 through an opening in the 
front end 24 of the main body 20 is a motor 38 providing a source of power 
rotating the axle 36 in a substantially circular direction along the 
center axis of the main body 20. Said motor 38 may preferably be a direct 
current variable speed motor, but is not intended to be restricted 
thereby. 
Divider panels 40, having a first 42 end and a second end 44, may be 
rigidly fastened by any suitable means at said first end 42 to the axle 
36. Accordingly, the divider panels 40 extend radially outward from said 
axle 36. Although the divider panels 40 could, of course, be made from a 
wide variety of suitable materials, the preferred embodiment of the 
present invention provides divider panels 40 composed of stainless steel. 
Said divider panels 40 apportion the main body 20 of the windshield curing 
apparatus 10 into preferably four distinct and separate chambers 28, 30, 
32 and 34, as shown in FIG. 2. In addition, each divider panel 40 has an 
appropriate sealing means 48 fastened to the second end 44 of each panel 
40 to ensure the four chambers 28, 30, 32 and 34 are environmentally 
separate and distinct. 
Each chamber 28, 30, 32 and 34 of the windshield curing apparatus 10 may 
contain a windshield holder assembly 50. The windshield holder assembly 50 
comprises at least one rigid support post 52 having a first end 54 and a 
second end 56. The preferred embodiment of the present invention 
illustrates a windshield holder assembly 50 comprising two rigid support 
posts 52. Said first end 54 of each support post 52 is rigidly attached to 
the axle 36, as shown in FIG. 2. On the second end 56 of each support post 
52 is mounted a vacuum cup 58 secured thereto by a suitable fastening 
means. 
As shown is FIG. 1, the support posts 52 being rigidly attached to the axle 
36 of the main body 20 and extending outward therefrom, are positioned a 
substantial distance apart to allow a windshield 11 to be held and 
supported in place by the vacuum cups 58 mounted on the second end 56 of 
each support post 52. The lips of the vacuum cups 58 facilitate a 
suction-hold on the windshield 11 when an external vacuum pump 70 is 
activated. The second end 56 of the support post 52 may be extended to 
within at least six inches of the main body 20 for allowing adequate room 
when applying an adhesive promoter to the windshield 11. 
As illustrated in FIG. 3, the main body 20 of the preferred embodiment may 
be apportioned into preferably four separate and distinct chambers 28, 30, 
32 and 34 by the divider panels 40. Likewise, the main body 20 may also be 
separated into preferably four distinct environments 12, 14, 16 and 18. 
The four chambers 28, 30, 32 and 34 are rotated through the four 
environments 12, 14, 16 and 18 by the motor 38 attached to the axle 36 at 
the front end 24 of the main body 20. For rotating the chambers 28, 30, 32 
and 34 through the distinct environments 12, 14, 16 and 18 of the 
windshield curing apparatus 10, are palm buttons 46 which control the 
motor 38 as it rotates the divider panels 40 through the different 
chambers 28, 30, 32 and 34, as shown in FIG. 1. 
The motor 38 rotates the axle 36 substantially 90 degrees during designated 
time intervals. The estimated time interval for a 90 degree rotation of 
the divider panels 40 from one chamber into another involves a period of 
time approximating a 3-4 minute index cycle. Although the conditions of 
the preferred embodiment allow for approximate 3-4 minute index cycles, 
said time intervals are not intended to be restricted thereby, but are 
dependant upon the environmental conditions maintained in each of the 
chambers 28, 30, 32 and 34 located within the main body 20 of the 
windshield curing apparatus 
As shown in FIG. 3, distinct and separate environments 14, 16 and 18 are 
maintained at predetermined temperature levels by heaters 61, 62 and 63 
which connect to the main body 20 in three locations and a steam generator 
65. The first environment 12 is maintained at room temperature and is used 
for loading and unloading of the windshields 11 into chamber 28. As the 
windshield holder assembly 50 in chamber 28 is rotated by the motor 38 
into chamber 30, the windshield 11 is positioned into a second environment 
14. A first heater unit 61 provides heat to the second environment 14 to 
substantially maintain a temperature between 200.degree. F. and 
260.degree. F. to flash off the adhesive promoter's toluene carrier. 
The windshield holder assembly 50 in chamber 30 is further rotated into 
chamber 32, where the windshield encounters a distinct third environment 
16. A second heater unit 62 and a steam generator 65 may be used to pump 
heat and steam into the third environment 16 to substantially maintain a 
temperature between 150.degree. F. and 200.degree. F. providing a means of 
humidity between 80 and 90 percent to promote hydrolysis. 
The windshield holder assembly 50 in chamber 32 may be further rotated into 
chamber 34 and into a fourth environment 18, where a third heater 63 pumps 
heat into said fourth environment 18 to substantially maintain a 
temperature between 200.degree. F. and 250.degree. F. for drying the 
windshield 11 and evaporating the water from the laminate. Finally, the 
windshield holder assembly 50 in chamber 34 may be rotated into chamber 28 
for removal of the windshield 11 and the addition of another. 
Once a windshield 11 has passed through the four separate and distinct 
curing environments 12, 14, 16 and 18 of the windshield curing apparatus 
10, the windshield 11 may be removed from the apparatus 10 by a worker 
using hand held vacuum cups. After the worker places the hand held vacuum 
cups on the windshield 11, he may release the suction-hold between the 
vacuum cups 58 secured to the second end 56 of the support posts 52 and 
engaging the newly cured windshield 11, by pressing a foot pedal 60 which 
disengages the external vacuum pump 70 releasing the vacuum suction-hold 
by a method familiar in the art. 
From the above discussion, it will be appreciated that the present 
invention provides a novel windshield curing apparatus and method for 
curing an adhesive promoter on a windshield in preparation for 
encapsulation. Whereby, the present invention provides an apparatus and 
method which shortens the period of time for curing an adhesive promoter 
on a windshield and does not involve the high costs of storing the 
windshield in high humidity rooms during the curing process. 
Furthermore, the present invention provides a means whereby the curing of 
windshields produces a more consistent product with fewer defects and is 
no longer a labor intensive process. Thus, the present invention provides 
significant advantages over the prior art methods of curing windshields 
now in known use. 
The present invention may be embodied in other specific forms without 
departing from its spirit or essential characteristics. The described 
embodiments are to be considered in all respects only as illustrative, and 
not restrictive. The scope of the invention is, therefore, indicated by 
the appended claims, rather than by the foregoing description. All changes 
which come within the meaning and range of equivalency of the claims are 
to be embraced within their scope.