System and method for reducing viscosity variations in roofing asphalt

Abstract

An asphalt shingle coating system that includes a coater, a mixer, a viscosity gauge, a wax supply, a wax pump and a control system. The coater applies a layer of a coating asphalt mixture on an asphalt shingle substrate. The mixer mixes the coating asphalt mixture and is positioned upstream of the coater. The viscosity gauge may be positioned between the coater and the mixer, and it measures the viscosity of said coating asphalt mixture before it is delivered to the coater. The wax supply is in fluid communication with the mixer and a wax pump may deliver a volume of wax from the wax supply to the mixer, and the control system may selectively adjust the operation of the wax pump to substantially maintain a desired viscosity of said coating asphalt mixture.

What is claimed is: 
     
         1 . An asphalt shingle coating system comprising:
 a coater for coating an asphalt shingle substrate with a coating asphalt mixture;   a mixer for mixing said coating asphalt mixture, said mixer in fluid communication and upstream of said coater;   a viscosity gauge for measuring the viscosity of said coating asphalt mixture delivered to said coater, said viscosity gauge disposed between said coater and said mixture;   a wax supply in fluid communication with the mixer;   a wax pump for delivering a volume of wax from the wax supply to the mixer; and   a control system in electronic communication with said viscosity gauge and said wax pump, said control system operable to selectively adjust the operation of said wax pump to substantially maintain a desired viscosity of said coating asphalt mixture.   
     
     
         2 . The asphalt shingle coating system of  claim 1  further comprising a supply return valve and a supply return line for directing and conveying the asphalt coating back to the mixer if the asphalt coating is out of specification. 
     
     
         3 . The asphalt shingle coating system of  claim 1  wherein the mixer includes two or more level sensors used to determine the amount of wax to be added to result in the desired proportions and material properties. 
     
     
         4 . An asphalt shingle coating system comprising:
 a coater for coating an asphalt shingle substrate with a coating asphalt mixture;   a mixer for mixing said coating asphalt mixture, said mixer upstream of said coater;   a supply conduit connecting said coater and said mixer for placing said mixer in fluid communication with said coater;   a static mixer tube disposed in said supply conduit;   a viscosity gauge for measuring the viscosity of said coating asphalt mixture delivered to said coater, said viscosity gauge disposed between said coater and said mixture and downstream of said static mixer;   a wax supply in fluid communication with the supply conduit, the wax supply having an inlet into said supply conduit upstream of the static mixer;   a wax pump for delivering a volume of wax from the wax supply to the static mixer; and   a control system in electronic communication with said viscosity gauge and said wax pump, said control system operable to selectively adjust the operation of said wax pump to substantially maintain a desired viscosity of said coating asphalt mixture.   
     
     
         5 . A method for substantially maintaining the viscosity of a coating asphalt mixture delivered to a coater during the manufacture of a roofing shingle, the method comprising the steps of:
 measuring the viscosity of the coating asphalt mixture prior to the asphalt mixture being delivered to the coater;   comparing the measured viscosity to a desired viscosity; and   adjusting the amount of wax in the coating asphalt mixture if the measured viscosity varies from said desired viscosity.   
     
     
         6 . The method of  claim 5  further comprising adding wax to the coating asphalt mixture if the measured viscosity is higher than said desired viscosity range. 
     
     
         7 . The method of  claim 5  further comprising reducing the amount of wax added to the coating asphalt mixture if the measured viscosity is lower than said desired viscosity range. 
     
     
         8 . The method of  claim 5  further comprising mixing the coating asphalt mixture until the mixture is at least substantially homogeneous.