Patent Application
20180318867
This disclosure relates generally to asphalt shingle manufacturing and more specifically to devices and methods for applying a self-seal or sealant strip to shingles during the manufacturing process.
Modern asphalt roofing shingles generally are formed from asphalt saturated and coated fibrous webs covered on an upper side with protective ceramic granules. Each shingle includes an upper headlap portion and a lower portion that is exposed on a roof. The headlap portion is designed to be overlapped by the lower portions of a next higher course of shingles when the shingles are installed. The lower portion often is separated by slots into individual tabs of the shingle, which are exposed on a roof after installation. Other shingle configurations also exist. For example, higher end roofing shingles may comprise two laminated plies of shingle material adhered together with at least the top ply being cut into tabs commonly known as “dragon teeth” to lend texture and the appearance of thickness to a shingle installation.
Regardless of the style of asphalt shingle, raising and consequent tearing of exposed shingle tabs during high wind conditions can result in rainwater leakage and ultimate failure of a shingle system. It therefore is highly desirable and even necessary that the exposed portions of asphalt shingles be adhered to the headlap portion of underlying shingles to minimize the rising or lifting of the exposed portions caused by high winds. This is commonly accomplished for simple strip or tab shingles by the application of a sealant strip to the headlap portions on the front sides of shingles just above the lower exposed portions. For architectural laminate shingles, sealant typically is applied to the lower back side of each shingle. Other configurations and placements are possible.
The sealant strips soften between courses of shingles when shingles are heated by the sun to bond the overlapping exposed portions of one course of shingles to the headlap portions of shingles in a next lower course. Such strips often referred to as “self-seal strips” usually are applied in a discontinuous line defined by short dashes of sealant separated by short spaces that contain no sealant. The spaces are important because they allow moisture that may penetrate or condense between overlapping shingles to drain through the spaces between the bonded dashes of the strip. Discontinuous strips also reduce the amount of sealant needed.
In the past, self-seal strips have been applied during the manufacturing process by moving a web of shingle stock over a rotating self-seal applicator wheel that contacts or passes closely adjacent the shingle stock to apply the sealant. The applicator wheel has a peripheral surface that in one embodiment is defined by a plurality of lands often called “footprints” separated by gaps. In operation, the wheel is rotated about its horizontal axis with a surface speed that may be substantially the same as the line speed at which the shingle stock is moving above. Alternatively, the wheel may be rotated at a rate such that its surface speed is different from the line speed to obtain a preferred result. The peripheral surface of the wheel passes downwardly through an underlying reservoir carrying liquid sealant and, in turn, picks up sealant on its footprints. The loaded footprints then rotate upwardly to contact the moving web of shingle stock and the sealant on the footprints is transferred to the shingle stock. Because the footprints are spaced apart by gaps, this produces intermittent dashes of sealant separated by spaces extending along the shingle stock, which together define the self-seal strip.
While the above technique for applying a self-seal strip has proven adequate at lower line speeds commonly used in the past, it has been found to be inadequate at higher line speeds. This is at least in part because, at such higher speeds, the applicator wheel must be rotated at higher rotation rates for its surface speed to match or approximate or be some multiple of the speed at which the shingle stock is moving above. Under high speed operating conditions, sealant picked up by the footprints of the applicator wheel in the reservoir tends to slide rearwardly and at least partially off of the trailing ends of the footprints as it is carried up and around to be applied to the shingle stock. This can also be a problem for manufacturing plants with smaller diameter applicator wheels since smaller wheels must operate at higher revolutions per minute (rpm) than larger wheels.
Ever higher line speeds in shingle manufacturing are desirable because they increase production rates. However, because of the above noted problems, the quality of applied self-seal strips degrades as line speed increases. It has been found, for example, that the dashes of a self-seal strip applied at higher line speeds become inconsistent. Because the sealant has slid or shifted toward the trailing edges and some has slipped off the trailing edges of the footprints as the footprints are moved up from the reservoir, the dashes of sealant can be overly thick at one end and overly thin at the other. Sealant that may slide off of the trailing ends of the footprints also can result in “bridging” between dashes of sealant. This can compromise the moisture draining function of the spaces between the dashes and even result in shingles that must be rejected as not meeting quality standards.
A need exists for a method and apparatus that can apply self-seal strips to moving shingle stock webs at higher line speeds without compromising the quality of the dashes of the strip or causing stringing and bridging between dashes. It is to the provision of such a method and apparatus that the present invention is primarily directed.
Briefly described, a sealant strip applicator comprises an applicator wheel rotatable about a horizontal axis below (or above) a moving web of shingle stock. The peripheral surface of the applicator wheel is formed with a plurality of footprints separated by gaps between the footprints. Each footprint is characterized by outwardly projecting side walls that bound and partially define a depressed area, which may take the form of a groove, extending along the surface of the footprint. As the peripheral surface of the applicator wheel rotates down through the sealant in the reservoir, sealant is picked up by the footprints, especially within the groove defined between the side walls of each footprint. The sealant is carried upwardly with the footprints until the footprints engage the surface of moving shingle stock above, whereupon the sealant is transferred from the grooves of the footprints to the shingle stock, forming the sealant dashes separated by gaps characteristic of a self-seal strip.
According to the invention, a backstop in the form of an upstanding end wall is formed on each footprint spanning across the groove at the trailing end of the footprint. Further, one or more mid-stops may be formed in each footprint and may take the form of upstanding walls spanning the groove of each footprint intermediate its leading end and its trailing end. The backstops intercept sealant that might otherwise tend to slide rearwardly off the trailing ends of the footprints thus keeping the sealant within the groove. The mid-stops retain the sealant in the mid-portions of the grooves so that it does not tend to pile up or bunch up at the trailing ends of the grooves. As a result, the sealant is held in the grooves of the footprints and is prevented from moving rearwardly and sliding off the trailing ends of the footprints, even at high line speeds. As a consequence, the sealant dashes applied to the shingle stock at high speeds are more fully formed, troublesome bridging between dashes is reduced or eliminated, and the self-seal strip is more consistent along its length, thereby improving performance.
Thus, a method and apparatus for applying self-seal strips to shingles is now provided that successfully addresses the problems of the prior art and results in high quality sealing strips at much higher line speeds. These and other aspects, features, and advantages of the invention will be better appreciated upon review of the detailed description presented below when taken in conjunction with the accompanying drawing figures, which are briefly described as follows.
Reference will now be made in more detail to the attached drawing figures, wherein like reference numerals indicate like parts where appropriate throughout the views.
The sealant applicator 11 includes a reservoir 14 that contains a supply of sealant 16. The sealant may be an asphalt, and adhesive, or any other liquid material intended to be applied to the shingle stock above. An applicator wheel 17 is mounted at least partially within the reservoir for rotation about a horizontal axis that extends perpendicular to the direction 13. The applicator wheel 17 is formed with a plurality footprints 18 extending around the periphery of the applicator wheel 17. The footprints are separated by gaps 19. The gaps 19 extend inwardly to merge with cutouts 21 in the applicator wheel that function to collect and shed excess sealant that may fall through the gaps 19. The cutouts 21 may be circular, U-shaped, or otherwise shaped as desired.
A drive mechanism (not shown) is coupled to the applicator wheel and is controlled to rotate the wheel in direction 22 at a desired rate. The desired rate preferably is such that the surface speed of the footprints 18 is substantially the same as the line speed at which the shingle stock 12 moves in the processing direction 13. As the applicator wheel rotates, the footprints 18 are moved through the supply of sealant 16 in the reservoir 14 and each footprint picks up a charge of sealant (e.g. charge 23). The charges of sealant are then transported by the footprints around and up toward the moving shingle stock 12. At the top of the applicator wheel, the footprints engage the moving shingle stock and the charges of sealant carried by the footprints are transferred to the shingle stock. This, in turn, creates a strip of sealant along the shingle stock characterized by dashes of sealant separated by spaces between the dashes, i.e. a “self-seal strip.”
As mentioned,
This phenomenon is illustrated in
Sealant charge 31 has been carried by its footprint into contact with the moving shingle stock above and is being transferred to the shingle stock to form a sealant dash. However, because the charge 31 has become misshapen during its journey around and up, the resulting dash on the shingle stock is applied unevenly. For instance, there may be an excess of sealant at the beginning of the sealant dash and comparatively little sealant at the end of the sealant dash. This is illustrated at 32 in
During operation of the sealant applicator wheel 17 at high speeds in high speed shingle manufacturing, each footprint 18 of
A third upstanding wall 48 spans the trailing end of the trough and forms a backstop 56 at the trailing end. A fourth upstanding wall 49 spans the trough ahead of the wall 48 and forms a first mid-stop 57. The third and fourth upstanding walls define between them a rear trough section 54 in the trailing portion of the footprint. Similarly, a fifth upstanding wall 51 spans the trough ahead of the fourth upstanding wall 49 and defines a second mid-stop 58. The fourth and fifth upstanding walls 49 and 51 define between them an intermediate trough section 53. A forward trough section 52 is formed ahead of the fifth upstanding wall and terminates at the leading end of the footprint.
During operation of the sealant applicator wheel 17 at high speeds in high speed shingle manufacturing, each footprint 18 of
This, in turn, helps to maintain an even distribution and consistent shape of the sealant charge along the length of the footprint. When the footprint contacts the moving shingle stock at the top of its travel, the more evenly distributed and more consistently shaped charge of sealant is transferred to the shingle stock. This forms a dash of sealant on the shingle stock that is more consistent, more fully formed, and that exhibits higher performance when shingles are ultimately installed on a roof deck. Further, the entire self-seal strip applied to the shingles is more uniform and bridging between sealant dashes caused by sealant in the gaps between footprints is greatly reduced or eliminated.
The invention has been described and exemplified herein in terms of preferred embodiments and methodologies considered by the inventor to represent the best modes of carrying out the invention. It will be understood, however, that a wide gamut of additions, deletions, and modifications, both subtle and gross, might well be made by skilled artisans without departing from the spirit and scope of the invention. The scope of the invention is not to be determined by the examples presented and described herein, but rather is delineated only by the claims hereof.
Priority is hereby claimed to the filing date of U.S. provisional patent application 62/503,056 filed on May 8, 2017.
| Number | Date | Country | |
|---|---|---|---|
| 62503056 | May 2017 | US |
