Abstract:
The present invention provides a method of forming hybrid and composite filters, which are more durable than that of the prior art. The method of forming a hybrid tubular filter includes wrapping a first layer of fiber, wrapping a filtering material and then wrapping a second layer of fiber. A mandrel is retained in a lathe chuck or the like and an end of fiber is attached to the mandrel. A fiber guide moves parallel to a length of the mandrel according to the direction of a control device. The method of forming a composite tubular filter includes wrapping a first layer of fiber around a mandrel.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to tubular filters and more specifically to a method of forming hybrid and composite tubular filters, which are less expensive to manufacture than filters fabricated from other materials. 
     2. Discussion of the Prior Art 
     There are numerous water filters in the art. One type of water filter is constructed from a perforated metal tube that is terminated on each end with metal end tubes. A woven wire cloth screen is attached to an inside surface of the perforated metal tube. The manufacture of this water filter is not inexpensive. Further, the woven wire cloth screen may pull away from the inside perimeter of the perforated metal tube. 
     Accordingly, there is a clearly felt need in the art for a method of forming a hybrid tubular filter, which positively retains a screen and tubular filters, which are more economical to manufacture than that of the prior art. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method of forming hybrid and composite tubular filters, which are less expensive to manufacture than filters fabricated from other materials. Tubular filters commonly have a round outer perimeter, but could have a square, rectangular or an outer perimeter with any other appropriate shape. The method of forming a hybrid tubular filter includes wrapping a first layer of fiber, wrapping a filtering material and finally wrapping a second layer of fiber. The fiber or tow includes a plurality of filaments and a binder. Additional binder may be added to the fiber in a second operation. A mandrel is retained in a rotary chuck or the like. An end of the fiber is attached to the mandrel. A fiber guide moves the fiber back and forth, parallel to an axis of the mandrel according to the direction of a programmable controller. If additional binder is required, the fiber is run across a binder cylinder. The binder cylinder is rotated to collect binder contained in a bath. The binder adheres to the fiber as thereof moves across the binder cylinder. If no additional binder is required, the fiber may be run through a heating device, which heats the binder contained in the fiber. However, preheating the fiber is not always required. The fiber guide moves the fiber back and forth along a length of the mandrel, until a predetermined amount of fiber is applied to the mandrel. 
     The programmable controller stops the rotation of the mandrel, after the first layer of fiber is wrapped around the mandrel. The fiber is oriented to be at one end of the mandrel. Preferably, a filtering material is temporarily retained around the first layer of fiber. A second layer of fiber is slowly wrapped around the filtering material, until the flat filtering material is secured around the first layer of fiber. The second layer of fiber is then applied at a normal speed, until a predetermined amount of fiber is applied over the filtering material. The end diameters of the hybrid tubular filter may be increased by winding thereof with additional fiber. The end diameters may be further modified by machining thereof to fit the inner diameter of a filter housing or the like. The end diameters may be machined by grinding, turning or any other suitable process. 
     The method of forming a composite tubular filter includes wrapping a first layer of fiber around a mandrel. An end of the fiber is attached to the mandrel. A fiber guide moves the fiber parallel to an axis of the mandrel according to the direction of a programmable controller. If the fiber requires additional binder, then the filament collects binder retained on the binder cylinder. If the fiber does not require additional binder, the fiber may be run through a heating device. The fiber guide moves the fiber back and forth along a length of the mandrel, until a predetermined thickness of fiber is applied to the mandrel. The end diameters of the composite tubular filter may be increased by winding with additional fiber. The end diameters may be further modified by machining thereof to fit the inner diameter of a filter housing or the like. 
     Accordingly, it is an object of the present invention to provide a hybrid tubular filter, which positively retains a filtering material. 
     It is a further object of the present invention to provide a composite tubular filter, which does not corrode in a fluid. 
     Finally, it is another object of the present invention to provide tubular filters, which are more economical to manufacture than that of the prior art. 
     These and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a portion of a fiber winding apparatus utilizing a binder bath in accordance with the present invention. 
         FIG. 1   a  is a perspective view of a portion of a fiber winding apparatus utilizing a heater device in accordance with the present invention. 
         FIG. 2  is a side view of a first layer of fiber of a hybrid or composite tubular filter in accordance with the present invention. 
         FIG. 3  is a side view of a filtering material secured around a first layer of fiber of a hybrid tubular filter in accordance with the present invention. 
         FIG. 4  is an end view of a filtering material partially wrapped around a first layer of fiber of a hybrid tubular filter in accordance with the present invention. 
         FIG. 5  is an end view of a filtering material fully wrapped around a first layer of fiber of a hybrid tubular filter in accordance with the present invention. 
         FIG. 6  is a side view of a second layer of fiber wrapped around a filtering material of a hybrid tubular filter in accordance with the present invention. 
         FIG. 7  is a side view of a hybrid tubular filter having ends that have been increased in diameter in accordance with the present invention. 
         FIG. 8  is a side view of a hybrid tubular filter having ends that have been machined to fit an inner diameter of a housing or the like in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference now to the drawings, and particularly to  FIG. 1 , there is shown a perspective view of a portion of a fiber winding apparatus  100 . The fiber winding apparatus  100  preferably includes a rotary chuck  102 , a drive source  104 , a mandrel  106  and a fiber guide  108 . However, other devices may be used to wrap fiber around a mandrel. If additional binder is applied to the fiber, the fiber is run through a binder bath (resin bath)  110 . The binder bath  110  includes a bath container  111 , a quantity of binder  112  and a binder cylinder  114 . With reference to  FIG. 1   a , if additional binder  112  is not applied to a fiber, then a heating device  115  may be used to heat the binder contained in the fiber  119 . However, preheating the fiber  119  is not always required. A tubular filter fabricated from a fiber without additional binder added thereto typically has to be heated in a secondary operation. The secondary heating operation is well known in the art and need not be explained in further detail. 
     Many different filament materials and binders exist in the art. For example, fibers that may or may not require additional binder include filaments of Kevlar, carbon or fiberglass. A fiber having polypropylene filaments, does not have to have additional binder applied thereto. However, the fiber having polypropylene filaments may be preheated in the heating device  115 . The appropriate fiber is dependent upon the application for the tubular filter. 
     A projection end  116  of the mandrel  106  is retained in the rotary chuck  102  or the like. A longer mandrel  106  will require support on both ends. The rotary chuck  102  is rotated by the drive source  104 . An end of a piece of fiber  118 ,  119  is attached to the mandrel  106 . The fiber guide  108  is retained adjacent the mandrel  106 . If additional binder  112  is applied to the fiber  118 , the binder cylinder  114  is rotated relative to the bath container  111 , such that the linear velocity of the fiber  118  is equal to the velocity of the outer diameter of the binder cylinder  114 . The rotation of the binder cylinder  114  collects binder  112  on the outer diameter from a bottom of the bath container  111 . The binder  112  adheres to the fiber  118  as thereof moves across the outer diameter of the resin cylinder  114 . The fiber guide  108  is moved back and forth relative to an axial length of the mandrel  106 , until a predetermined amount of fiber  118 ,  119  is applied to the mandrel  106 . Fiber winding apparatuses are well known in the art and need not be explained in further detail. 
     With reference to  FIGS. 2-6 , a method of forming a hybrid tubular filter  1  includes wrapping a first layer of fiber  10 , wrapping a filtering material  12  and finally wrapping a second layer of fiber  14 . After an end of the fiber  118 ,  119  has been secured to the mandrel  106 , the fiber guide  108  is moved back and forth along the length of the rotating mandrel  106  to produce an open helical pattern of the first layer of composite material  10  with a particular thickness. The creation of the open helical pattern of the first layer  10  is not offered by a programmable controller used with the fiber winding apparatus machine  100  or any other fiber winding machine. The programmable controller  120  can be characterized as a control device. Other control devices besides the programmable controller  120  may be used, such as a changeable gear drive. 
     The open helical pattern is created by choosing a fiber width that is narrower than that entered into the programmable controller  120 . The programmable controller  120  uses a width of fiber that will normally produce a solid cylinder. However, in creation of a filter, there must be a plurality first openings  16  formed through the first layer of fiber  10  to allow the flow of fluid therethrough. The narrower fiber width creates the plurality of first openings  16 . The following parameter is given by way of example and not by way of limitation. Satisfactory results have been found by using a width of fiber that is 20% of that entered into the programmable controller  120 . However, other percentages may also be used. The greater the percentage the smaller the openings. The plurality of first openings  16  allow fluid to flow through the filtering material  12 . 
     The programmable controller  120  stops the rotation of the mandrel  106 , after the first layer of fiber  10  is wrapped around the mandrel  106 . With reference to  FIG. 3 , the composite fiber  118 ,  119  is oriented to be at one end of the mandrel  106 . Preferably, the filtering material  12  is temporarily retained around the first layer of fiber  10 . The filtering material  12  may be held in place by hand, attached with glue, attached with adhesive or through any other suitable method. The filtering material  12  is preferably a woven wire cloth screen or a membrane sheet, but other filtering elements may also be used. The fiber  118  is slowly wrapped around the filtering material  12 , until the filtering material  12  is secured around the first layer of fiber  10 . 
     The second layer of fiber  14  is then wrapped at a normal speed, until a predetermined amount of fiber  118 ,  119  is wrapped around the flat filtering material  12 . The second layer of fiber  14  also includes the open helical pattern that creates a plurality of second openings  18 . Fluid flows from an inside perimeter of the hybrid tubular filter  1  to an outside perimeter by flowing through the plurality of first openings  16 , the filtering material  12  and the plurality of second openings  18 . Fluid may also flow from an outside perimeter of the hybrid tubular filter  1  to an inside perimeter thereof. 
     With reference to  FIG. 7 , a magnitude of a first end diameter  20  and a second end diameter  22  of the hybrid tubular filter  1  may be increased by winding with additional fiber. With reference to  FIG. 8 , the first and second end diameters may be further modified by machining thereof to fit the inner diameter of a filter housing or the like. A reduced diameter  24  is formed on the first end diameter  20 ′ and a chamfer  26  is formed on the second end diameter  22 ′. The first and second end diameters may be machined by grinding, turning or any other suitable process. 
     With reference to  FIG. 2 , the method of forming a composite tubular filter  2  includes wrapping a first layer of fiber  10  around the mandrel  106 . An end piece of the fiber  118 ,  119  is attached to the mandrel  106 . The fiber guide  108  moves the fiber  118 ,  119  back and forth along a length of the mandrel  106  according to the direction of the programmable controller  120  to apply a predetermined thickness of the fiber  118 ,  119 . The thickness of the first layer of fiber  10  for the composite tubular filter  2  must be greater than that of the hybrid tubular filter  1 , because of the single layer of fiber. 
     The open helical pattern created for the hybrid tubular filter  1  is also created in the composite tubular filter  2  to produce the plurality of first openings  16  to allow the flow of fluid therethrough. A narrower fiber width than that entered into the programmable controller  120  creates the plurality of first openings  16 . A fiber width of 20% of that entered into the programmable controller may be used or a different percentage may be used to accommodate different filtering requirements. The greater the percentage, the smaller the openings. The end diameters of the composite tubular filter  2  may be increased by winding additional fibers thereupon as shown in  FIG. 7 . The end diameters may be further modified by machining thereof to fit the inner diameter of a filter housing or the like as shown in  FIG. 8 . 
     While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.