Abstract:
A bathing vessel has a first and a second sandwiched wall, each wall having a first layer of polyurethane material, a second layer of polyurethane material attached to the first layer, a third layer of acrylonitrile butadiene styrene (ABS) material attached to the second layer, and a fourth layer of acrylic material attached to the third layer. A load element is disposed across and is integral with the first and second sandwiched walls. The load element distributes a load on one wall to an other wall and is visible to users of the bathing vessel. The load element is also a design element.

Description:
RELATED APPLICATION 
     This application claims priority to U.S. Provisional Application No. 61/413,575, which was filed Nov. 15, 2010. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to composite bathing vessels. 
     BACKGROUND 
     Bathing vessels such as showers and bathtubs have surrounds that are subject to stresses. The walls may support grab bars and towel bars, and users may interact with the walls of the surrounds by stressing them. 
     Bathing vessels may be manufactured from a variety of different materials, such as plastic materials. Plastic bathing vessels, however, must meet certain minimum performance requirements. For instance, the American National Standards Institute (ANSI) sets forth minimum physical requirements and testing methods for plastic bathtub and shower units. A bathing vessel that meets the requirements is approved for use in homes, buildings or other structures as a plumbing fixture. 
     SUMMARY 
     According to an embodiment shown herein, a bathing vessel has a first and a second sandwiched wall, each wall having a first layer of polyurethane material, a second layer of polyurethane material attached to the first layer, a third layer of acrylonitrile butadiene styrene (ABS) material attached to the second layer, and a fourth layer of acrylic material attached to the third layer. A load element is disposed across and is integral with the first and second sandwiched walls. The load element distributes a load on one wall to an other wall and is visible to users of the bathing vessel. The load element is also a design element. 
     According to a further embodiment shown herein, a bathing vessel has a first and a second sandwiched wall, each wall having a first layer of polyurethane material, a second layer of polyurethane material attached to the first layer, and a third layer of acrylonitrile butadiene styrene (ABS) material attached to the second layer. A load element is disposed across and is integral with the first and second sandwiched walls. The load element distributes a load on one wall to an other wall and is visible to users of the bathing vessel. The load element is also a design element. 
     According to a further embodiment shown herein, a method for constructing a bathing vessel includes the steps of: choosing a layered material defining a first wall and a second wall, the layered material having a first layer of polyurethane material, a second layer of polyurethane material attached to the first layer, and a third layer of acrylonitrile butadiene styrene (ABS) material attached to the second layer; determining a load to be distributed across the first wall and the second wall; forming a load element that is integral with and in the first and second walls that is visible to users, and crosses the first wall and the second wall to distribute the load across the first and the second wall; and, making the load element a design element. 
     According to a still further embodiment shown herein, a bathing vessel has a first and a second sandwiched wall and a load element that is integral with and disposed across said first and second sandwiched walls that distributes a load on one wall to the other wall and is visible to users of said bathing vessel wherein said load element is also a design element. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a one piece bathing vessel. 
         FIG. 2  is a side view of bathing vessel of  FIG. 1 . 
         FIG. 3  is a detailed view, taken along the lines  3 - 3  of  FIG. 2 . 
         FIG. 4  is a detailed view, taken along the lines  4 - 4  of  FIG. 2 . 
         FIG. 5  is side view of the material forming the bathing vessel of  FIG. 1 . 
         FIG. 6  depicts a method of designing a bathing vessel. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS. 1-3 , a perspective view of a one-piece bathing vessel  10 , including tub  25 , a surround  13 , a skirt  15  in front of the tub  25 , a deck  20  circling a top of the tub, a right sidewall  30  extending upwardly from the deck  20 , a left surround wall  35  extending upwardly from the deck  20  and a back wall  40  extending upwardly from the deck  25  and attaching to and integral with the left surround wall  35  and the right surround wall  30 . A nailing flange  45  is disposed around the bathing vessel  10  and is used to attach the bathing vessel  10  to a stud wall  70  or an attachment plane  75 . A design/load element  50  extends from the left surround wall  35  across the back wall  40  and across to the right side surround wall  30 . The curved portion  60  of the design/load element  50  has a back  65 . Though a one-piece bathing vessel is shown herein, one of ordinary skill in the art will recognize from the teachings herein, that a one-piece surround made of a side wall(s) and a back wall may also be constructed as taught herein. 
     Referring to  FIGS. 2 and 3 , details of the design/load element  50  are shown. But for the design element/load element  50 , and the nailing flange  45 , the back wall  40  and the right and left surround walls  30 ,  35  are disposed a distance D 1  of 0.05 inches from a stud wall  70  or an attachment plane  75 . Some requirements, such as for ANSI, require the sidewalls  30 ,  35  or back wall  40  not to deflect more than 0.25 inch. By keeping these walls less than 0.25 inch away from the stud wall  70  or attachment plane  75 , the distance these walls can deflect is less than 0.25 inch and the requirements are then met. Because of the flexibility of the walls  35 ,  40 ,  30 , given the material  57 , as will be discussed infra, uses, the D 1  should be less than or equal to 0.25 inches. The nailing flange  45  and the sidewalls and back walls  35 ,  40 ,  30 , each have a thickness D 2  of 0.070 inches. 
     The design/load element  50  has a ledge extending around the back wall  40  and the side walls  30 ,  35  and the curved area  60  also extending around the back wall  40  and the side walls  30 ,  35 . As seen in  FIG. 4 , the design/load element  50  is defined from behind the bathing vessel  10 . The curved area  60  helps give the design load element a better aesthetic look and feel to a user. The ledge  55  has a width D 3  of 1.69 inches. By creating the ledge and the curved area in conjunction with a material  57  as will be discussed infra, stresses on the back wall  40  and the side walls  30 ,  35  are absorbed into the design/load element  50  and distributed across the back wall  40  and the side walls  30 ,  35 . As a result, less material  57  may be utilized to effect a cost benefit for the bathing vessel  10 . Though a particular design/load element  50  is disclosed herein, other design/load element  50  are contemplated herein. The ledge  55  and curved area  60  bisect a span of each of the walls to shorten the span of the wall area holding the loads  80 ,  85  to facilitate increased rigidity while minimizing material requirements. 
     Referring to  FIG. 5 , the bathing vessel  10  is made of a material that is flexible yet rigid so that point loads on the walls such as grab bar  80  or grab bar  85  which typically require extensive local reinforcement  90  (see  FIG. 1 ), which may be a metallic panel that may attach to the studs  70 , do not require extensive local reinforcement of the back wall  40  or the side walls  30 ,  35  because the point load is distributed through the design/load element  50  across the sidewalls  30 ,  35  and the back wall  40 . 
     The material must be flexible and rigid to enable the load to be distributed across the back wall  40 , left side wall  35  and the right side wall  30 .  FIG. 4  shows a cross-section through a portion of one of the walls  35 . The walls  35  are a multi-layer structure that generally includes a first layer of polyurethane material  130   a , a second layer of polyurethane material  130   b , a layer of acrylonitrile butadiene styrene (ABS) material  130   c , and a layer of acrylic material  130   d  (collectively layers  130   a - d ), such as polymethylmethacrylate. As shown, the layer of acrylic material  130   d  is a top layer and is exposed for view to a user within the bathing vessel  20 . The layers  130   b  and  130   c  are intermediate layers, and the layer  130   a  is a bottommost layer that is generally obscured from view of a user within the bathing vessel  10 . Each of the layers  130   a - d  is bonded to its respective neighboring layer or layers. In embodiments, the specific materials and order of the layers  130   a - d  contributes to providing the bathing vessel with a desired degree of strength, such as to meet ANSI requirements. 
     In embodiments, the layer of acrylic material  130   d  is arranged on the first layer of polyurethane material  130   a , the layer of acrylonitrile butadiene styrene (ABS) material  130   c  is arranged between the layer of acrylic material  130   d  and the first layer of polyurethane material  130   a , and the second layer of polyurethane material  130   b  is arranged between the layer of ABS material  130   c  and the first layer of polyurethane material  130   a . In some examples, additional layers may be arranged among the layers  130   a - d . In other examples, the walls  35  include only the layers  130   a - d  and are free of other layers, materials, adhesives, or the like. 
     The thicknesses of the individual layers  130   a - d  is not necessarily shown to scale and may vary, depending on the desired wall strength and location in the wall  35 , for example. In embodiments, the ratio of the thickness of the layer of acrylic material  130   d  to the thickness of the layer of ABS material is no greater than 1, to facilitate meeting strength requirements. 
     In embodiments, the first layer of polyurethane material  130   a , the second layer of polyurethane material  130   b , or both, are foamed polyurethane materials. In some examples, the density of the first layer of polyurethane material  130   a  is different than the density of the second layer of polyurethane material  130   b . For instance, the density of the first layer of polyurethane material  130   a  is greater than the density of the second layer of polyurethane material  130   b , to facilitate achievement of a desired degree of strength of the walls  35 . 
     In a further example, the second layer of polyurethane material  130   b  is a rigid layer and has a density of 1-10 pounds per cubic foot. The first layer of polyurethane material  130   a  is an elastomeric layer and has a density of between about 25-65 pounds per cubic foot though in some examples approximately 55-65 pounds per cubic foot are used. In one example, the density is approximately 62 pounds per cubic foot. 
     Referring now to  FIG. 6 , local requirements, such as ANSI standards, may require walls  30 ,  35 ,  40 , to withstand point or other loads that have heretofore required extensive local reinforcement. If designing or constructing a bathing vessel  10  herein, a designer may choose to use the material  57  herein (step  95 ). The designer would then design a load element such as ledge  55 , taking into account the following variables: finite element analysis or the like how stresses of point loads are distributed around walls  30 ,  35 ,  40  in view of a proposed design (step  110 ); minimizing material  57  required as the design evolves (step  115 ) and minimizing local reinforcement  90  required (step  105 ). The designer then provides and aesthetic (step  120 ), such as curved area  60 , to make the bathing vessel attractive to consumers. By understanding that the material helps distribute the point or other loads with the inclusion of a design/load element  50 , the designer may include a design/load element  50  that is both aesthetic and provides support for the loads across the walls  30 ,  35 ,  40 . After designing a design/load element  50 , the designer may then opt for smaller local reinforcement, or a thinner material  57 . 
     It is commonly believed and accepted that the load displacement of the surface of the walls  30 ,  35 ,  40 , of the bathing vessel  10  is a function of the rigidity of the immediate area. However, it has been determined that by using less rigid materials, a load can be distributed throughout the unit by use of a design element that ties the walls together. In other words, a wrap around shelf or other design feature that has continuity across the back wall surface in carrying through the corner radius and onto each sidewall, can distribute the load across the entire unit. By distributing the load across the entire unit, thinner material may be used, allowing weight in material savings. 
     Furthermore, the embodiments shown utilize design elements to shorten the span of the wall area to facilitate increased rigidity while minimizing material requirements. In addition, the wall design elements use a minimum distance from the stud plane (or installation alcove surface) at key loading points to minimize the maximum deflection of the walls of the bathing vessel. 
     Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments. 
     The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.