Abstract:
The present invention relates to methods for joining a sub-shell for static reinforcement of a bathtub to a bathtub and a bathtub produced using said methods. This invention also relates to the section of sanitary and bath equipment made of plastic materials.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to methods for joining a sub-shell for static reinforcement of a bathtub to a bathtub and a bathtub produced using said methods. This invention also relates to the section of sanitary and bath equipment made of plastic materials. 
       BACKGROUND OF THE INVENTION 
       [0002]    Technical problem to be solved by this invention is: how to provide the static reinforcement of bathtub shells not using materials such polyester resins, glass fibers, various fillers and toxic volatile solvents, and to get final products of the same or better quality. 
         [0003]    Presently, the most used process for production of bathtubs, such described in for example in GB Patent application No. 2 266 261 (Klaus Jurgen, Fileis Roger, Folkard, 1993), made of plastic polymers includes providing an additional reinforcement of the bathtub shells. Reinforcement of a bathtub shell, regardless of the way it was produced, consists of sub-shell containing a mixture of polyester resin or glass fiber or some tillers, some specific chemical components as catalysts and solvents for chemical reactions. Said process could be performed only by using expensive equipment. 
         [0004]    However, process from this application has a number of shortcomings, such as:
       a rather extended production process;   ecological unacceptable production process causing exhausting of toxic and flammable substances;   using glass fibers in production process and in final installation of product bears a high risk of mechanical injuring of the workers;   high participation of various kinds of materials;   expensive equipment for application of polyester resin and glass fiber;   higher loses of material such as polyester resin in producing bathtub shells;   recycling of waste plastic materials is impossible because of using several different materials.       
 
         [0012]    Above mentioned shortcomings were a stimulus to author to drop existing process and made a completely new process for production of bathtubs made of plastic polymers. 
       SUMMARY OF THE INVENTION 
       [0013]    This invention relates to completely new processes for static reinforcement of bathtub shells. These processes are related to production of one or more sub-shells using the same material used to produce bathtub shell. 
         [0014]    One or more sub-shells are produced of the same material used to produce bathtub shell, applying some of known processes (using vacuum or by injecting plastic materials). 
         [0015]    Basic shape of sub-shell follows the shape of the bathtub shell, the sub-shell&#39;s bottom being profiled with regularly disposed polygonal bulges, reminding of honeycombs. 
         [0016]    This invention has, according to this patent application, a number of advantages, some of the more essential being:
       increased stability and much faster and cheaper production process   qualitative, simple and fast produced static reinforcement of the bathtub shell.   easy and fast connecting the sub-shell to bathtub shell   completely eliminated the use of polyester resin, glass fibers, fillers and equipment for application of said materials   ecological acceptable and conformed production procedures in all phases, including the installation of the final product   no extra costs in the production, sub-shell being made of the same material as the bathtub shell   a (grand) serial production is possible.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  shows, schematic, connection between the walls of the bathtub and the sub-shell in the case of the first variant of their connecting, 
           [0025]      FIG. 2  shows the second variant of the connection, 
           [0026]      FIG. 3  shows, schematic, the placing of bathtub in its sub-shell, 
           [0027]      FIG. 4  is a plan view of a bathtub produced by a process according to the present invention, 
           [0028]      FIG. 5  shows the side view of the bathtub shown on  FIG. 4 , 
           [0029]      FIG. 6  shows the longitudinal section of the bathtub shown on  FIG. 4 , 
           [0030]      FIG. 7  shows a cross section of the bathtub shown on  FIG. 4 , 
           [0031]      FIG. 8  shows the lower view of the bathtub shown on  FIG. 4 , 
           [0032]      FIG. 9  shows a detail of the supporting part of the sub-shell, said part providing support on the floor for the bathtub, and 
           [0033]      FIG. 10  shows a section of the detail shown on  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    1. Description of processes. Equipment necessary for the production of sub-shells for static reinforcement of bathtub shells is the same as the existing one used for production of bathtub shells, either by using vacuum or by applying some of known processes such as injecting of plastic materials. 
         [0035]    Mold used for providing sub-shells of desired form is of nearly the same size as the mold used for obtaining the basic product—the bathtub shells. Only difference between said molds is in that the mold for producing the sub-shell is providing a basic form for sub-shell—relief profiled surfaces with a number of polygonal bulges. 
         [0036]    Once the bathtub shell and sub-shell are fished, bathtub (a) is positioned in the sub-shell (b), as schematic shown in  FIG. 3 , followed by joining bathtub shell to the sub-shell. 
       1. Process of Joining the Bathtub Shell to the Sub-Shell for Static Reinforcement of Bathtub Shell by Using Some Kind of Glue. 
       [0037]    Pasting the bathtub shell to sub-shell is made with a glue obtained b\ mixing sawdust, made of wastes obtained during final processing of bathtub shells and sub-shells, with some saturated benzole based solution. 
         [0038]    Sub-shell, produced either by casting or in a mold for vacuum casting, is covered on the inner side with a rather thin layer of glue, either with a brush or by using some spraying tools. 
         [0039]    Following stage starts immediately after covering the inner side of the sub-shell with a layer of glue. The bathtub shell is placed in the sub-shell ( FIG. 3 ). Its outer surface is contacting the inner surface of the sub-shell, i.e. its flat surfaces covered with glue. The process of joining evolves so that the outer part of the bathtub shell contacting the flat surfaces covered with glue starts, when contacting the glue, to dissolve mildly, thus provoking the process of joining the bathtub shell to the sub shell Final result of said process is a bathtub wall consisting, as shown in  FIG. 1 , of three layers&#39; layer ( 1 ) containing material of the bathtub shell, layer ( 2 ) containing material of the sub-shell and a middle layer ( 3 ) containing the glue material. 
         [0040]    The basic process of joining takes up to one hour, depending on the thickness of the glue layer, the total time for finishing said process is twelve hours. 
         [0041]    Next step is the final mechanical treatment of edges and apertures. 
       2. Process of Joining the Bathtub Shell to the Sub-Shell for Static Reinforcement of Bathtub Shell by Ultrasonic Welding. 
       [0042]    For the joining by ultra sonic welding it is necessary to provide a minimum clearance between the bathtub shell and sub-shell. 
         [0043]    After putting the bathtub shell into the sub-shell ( FIG. 3 ) starts the process of ultrasonic-welding by applying appropriate devices. Final result of said process is a bathtub wall consisting, as shown in  FIG. 2 , of two layers: layer ( 1 ) containing material of the bathtub shell and layer ( 2 ) containing material of the sub-shell. 
         [0044]    2. The bathtub constructed using the processes according to this invention. Based on described processes, there is produced a bathtub having a bathtub shell joined to a sub-shell for the static reinforcement of the bathtub shell. There is shown a bathtub made by the process containing the gluing together the walls of bathtub shell and sub-shell. 
         [0045]    Bathtub ( 4 ) has, in a plan view, standard rectangular shape ( FIG. 4 ). The side view ( FIG. 5 ) has a customary shape, but on the lower edge there is shown a number of bulges ( 6 ). On  FIG. 6  there is shown the section B-B from the  FIG. 4 . It should be noted that bulges ( 6 ) are hollow. 
         [0046]    On  FIG. 7  there is shown the section A-A from the  FIG. 4 , including a detail showing the gluing of the walls of bathtub shell and sub-shell. 
         [0047]    On  FIG. 8  is shown the lower view of the bathtub shown on  FIG. 4 . There could be seen the bottom of the sub-shell ( 2 ) covered with bulges ( 6 ). On  FIG. 9  is shown a detail M of the supporting part of the sub-shell from which it could be seen that the bulges ( 6 ) consist of a net of hexagonal hollow bulges the bottom ( 7 ) thereof being the part of sub-shell. 
         [0048]    The bathtub bottom is supported by bulges ( 6 ) which take over the weight of the bathtub and transfer it, through their hexagonal walls, in the ground.