Abstract:
An inflatable product has a first layer and a second layer, each layer having a peripheral edge, with the first and second layers joined together along their peripheral edges to define an internal space for receiving air or fluid. Each layer has a uniform thickness throughout except that the thickness along the peripheral edge of each layer is greater than the thickness of the rest of the layer. A plurality of tension members can also be provided inside the internal space, each tension member having a first end that is joined to an inner surface of the first layer, and a second end that is joined to an inner surface of the second layer. Each tension member has a uniform thickness throughout except that the thickness along the first and second ends is greater than the thickness of the rest of the tension member.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an inflatable product, and in particular, to a connection structure for use with inflatable products. 
         [0003]    2. Description of the Prior Art 
         [0004]    At present, most of the inflatable products on the market are made up of a top layer and a bottom layer, which are made from environmentally friendly materials, such as PVC and TPU. For example, a current inflatable mattress is generally formed of a top layer having a uniform thickness and strength, a bottom layer, connecting coils that function as tension members, and a surrounding material layer. The top layer and the bottom layer are joined all around, through the surrounding material layer, by means of high-frequency welding, to form a sealed air chamber. A plurality of coils or tension members are joined between the top and bottom layers via high-frequency welding. In this manner, after the mattress is inflated, the top and bottom layers are kept flat under the pull of the tension members, so as to form the desired shape for the mattress. The top layer and the bottom layer typically both have a uniform thickness. When such a product is used, the base positions where the tension members are joined with the top and bottom layers are subject to a maximum stress. In addition, because the base positions where two layers having a uniform thickness and strength are joined by high-frequency welding become thinner due to welding, the stress-resistant strength of the base positions is much lower than that of the positions free from such welding. Therefore, the base positions are most likely to be torn during use, and the service life of the product is thus shortened. 
         [0005]    Thus, when inflatable products such as mattresses, inflatable pools, inflatable recreational products, life-saving and protecting products, and the like, are manufactured, it is necessary to improve the tensile strength of the base positions where the top layer and the bottom layer are joined, and to ensure that the joints of the top layer and the bottom layer are unlikely to be damaged during welding. One attempt to address this problem is to uniformly increase the overall thickness of the top layer and the bottom layer. However, this uniform increase in thickness increases the weight of resulting product, making it difficult to carry or transport, and also increases the cost of the product. 
         [0006]    There remains a need for an improved connection structure for inflatable products that avoids the drawbacks identified above. 
       SUMMARY OF THE DISCLOSURE 
       [0007]    It is an object of the present invention to provide an inflatable product that is durable and simple in construction. 
         [0008]    It is another object of the present invention to provide a method for manufacturing an inflatable product that has an improved connection structure between two layers of material. 
         [0009]    In order to accomplish the objects of the present invention, there is provided an inflatable product having a first layer and a second layer, each layer having a peripheral edge, with the first and second layers joined together along their peripheral edges to define an internal space for receiving air or fluid. Each layer has a uniform thickness throughout except that the thickness along the peripheral edge of each layer is greater than the thickness of the rest of the layer. 
         [0010]    A plurality of tension members can also be provided inside the internal space, each tension member having a first end that is joined to an inner surface of the first layer, and a second end that is joined to an inner surface of the second layer. Each tension member has a uniform thickness throughout except that the thickness along the first and second ends is greater than the thickness of the rest of the tension member. 
         [0011]    The present invention also provides a method of making the layers that have varying thicknesses. The present invention provides a first calendaring roller having a circular roller body, and a plurality of annular grooves provided in spaced-apart manner along the length of the roller body, and a second roller having a uniform smooth surface. The first roller is positioned from the second roller with a gap between the two rollers, and then a material is passed through the gap to create an extruded layer having thickened sections at the locations where the grooves are positioned along the first roller. 
         [0012]    In accordance with an embodiment of the present invention, the product is an inflatable mattress. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a schematic view of portions of a top layer and a bottom layer of an inflatable product according to the present invention, before being joined around its side edges by high frequency welding 
           [0014]      FIG. 2  is a cutaway cross-section view of a portion of the inflatable product of  FIG. 1  before welding. 
           [0015]      FIG. 3  is an enlarged view of the part A in  FIG. 2 . 
           [0016]      FIG. 4  is a schematic view of the inflatable product of  FIGS. 1-2  after welding. 
           [0017]      FIG. 5  is an enlarged view of the part B of  FIG. 4 . 
           [0018]      FIG. 6  is an enlarged view of the part C of  FIG. 5 . 
           [0019]      FIG. 7  is a top plan view of the inflatable product of the present invention, embodied as a mattress. 
           [0020]      FIG. 8  is a perspective cut-away view of the inflatable product of  FIG. 7 . 
           [0021]      FIG. 9  is a schematic view of a material calendaring roller according to the present invention. 
           [0022]      FIG. 10  illustrates the calendaring roller of  FIG. 9  in use with another roller with a uniformly smooth surface. 
           [0023]      FIGS. 11 and 12  are enlarged views of parts D and E of  FIG. 9 , respectively. 
           [0024]      FIG. 13A  illustrates a layer of material that is extruded from the roller of  FIG. 9 . 
           [0025]      FIG. 13B  is a cross-sectional view of the layer of material of  FIG. 13A . 
           [0026]      FIG. 14A  illustrates another layer of material that can be extruded from the roller of  FIG. 9 . 
           [0027]      FIG. 14B  is a cross-sectional view of the layer of material of  FIG. 14A . 
           [0028]      FIG. 15  illustrates how the thickened sections of the present invention are welded together. 
           [0029]      FIGS. 16A-C  illustrate three different ways of welding or joining a tension member to two layers of material. 
           [0030]      FIGS. 17A-C  illustrate three different ways of welding or joining one type of I-Beam two layers of material. 
           [0031]      FIGS. 18A-C  illustrate three different ways of welding or joining another type of I-Beam two layers of material. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]    The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims. 
         [0033]    Referring to  FIG. 1 , the present invention provides a connecting structure for inflatable products that have a top layer  1  and a bottom layer  2 . Thickened extensions  3  and  4  extend along the edges of the top layer  1  and the bottom layer  2 , respectively, and these extensions  3  and  4  are welded together along the bordering edges of the top and bottom layers  1  and  2  so as to form a sealed air-filled space. The thicknesses of the extensions  3  and  4  can be 0.01-0.06 mm greater than the thickness along the rest of the layers  1  and  2 . The top layer  1  and the bottom layer  2  may be joined by means of high frequency welding, directly or indirectly. By providing only the welded portions of the layers  1  and  2  to be thicker than the other parts of the layers  1  and  2 , the overall thickness of the layers  1  and  2  can be reduced, thereby reducing the production cost and the overall weight of the product. 
         [0034]    The connecting structure of the present invention can be used for inflatable mattresses, examples of which are shown in  FIGS. 7 and 8 . When used for inflatable mattresses, the top and bottom layers  1  and  2  also need to be joined via the use of tension members  5  that have opposite ends welded to the inner surfaces of the layers  1  and  2 . These tension members  5  are necessary to allow the mattress to be properly shaped. Specifically, after the mattress is inflated, the layers  1  and  2  are kept flat under the pulling of the tension members  5 . The tension members  5  can be joined between the layers  1  and  2  by means of high frequency welding. The tension members  5  can be arranged in a matrix (or other arrangement) as shown in  FIGS. 7 and 8 . The opposite ends of the tension members  5  are also provided with thickened end parts  31  and  41  for welding to thickened sections  311  and  411  provided on the inner surfaces of the top and bottom layers  1  and  2 , as shown in  FIGS. 2-4 . The end parts  31  and  41  can be thickened and elongated, and take on any shape (e.g., circular, elliptic, square or the like). The sections  311  and  411  can also be thickened and elongated, and take on any shape (e.g., circular, elliptic, square or the like), to correspond to the end parts  31  and  41 . 
         [0035]    For such a mattress, the thickness of the layers  1  and  2  is preferably about 0.3 mm (within a preferred range of 0.1-0.8 mm, which varies depending on different products), and the thickness of the sections  311  and  411  is preferably about 0.35 mm (within a preferred range of 0.1-0.8 mm, which varies depending on different products), so that the sections  311  and  411  can be joined by means of high frequency welding in a convenient manner while improving the tensile strength. 
         [0036]    For the mattress described above, a chamfer  42  is provided at a position where a thickened section  311  or  411  is in transition with the normal material of the layer  1  or  2 . In addition, for such a mattress, the radius R1 of the chamfer  42  can be 0.01 mm (see  FIG. 6 ). The purpose of the chamfer  42  is to avoid any sharp corners at the positions of corners and edges. 
         [0037]    As shown in  FIG. 6 , bulges at the parts for welding in the layers  1  and  2  are designed to be round or curved corners. This provides a uniform stress on the parts that are welded, and therefore improves the tensile strength. As a result, the resulting mattress (or product) is uniformly stressed after being inflated, and the base positions where the tension members  5  are joined to the layers  1  and  2  are unlikely to be torn. As a result, the mattress or product can enjoy improved durability and a longer service life. 
         [0038]    The present invention provides a roller processing mold and method that creates the unique layers  1  and  2  with thickened sections  3 ,  4 ,  31 ,  41 ,  311  and  411 , and also provides a method for welding the thickened sections together. 
         [0039]    Referring to  FIG. 9 , a material calendaring roller  100  is provided, which includes a circular roller body  101  that is adapted to contact the surface of a layer  1  or  2  of material, a rotating shaft  102  being correspondingly provided at both ends of the circular roller body  101 , and a plurality of annular grooves  103  provided in spaced-apart manner along the length of the roller body  101 . The provision of these grooves  103  creates peaks and valleys along the length of the roller body  101 , so that a layer  1  or  2  of material that is passed through this roller body  101  will have corresponding peaks P (thickened sections) and valleys V (sections with lesser thickness) configured or arrayed according to the pattern laid out on the surface of the circular roller body  1 . 
         [0040]    Referring to  FIG. 10 , when in use, the circular roller body  100  can be used in connection with another roller body  104  which has a completely uniform smooth surface. A certain gap G is maintained between the circular roller body  100  and the surface of the other roller body  104 , so that the calendared material can be extruded from this gap. In this way, the extruded material will contact the annular grooves  103  and be filled into the annular grooves  103 , thereby creating sections with a greater thickness at the locations of the annular grooves  103 . 
         [0041]    In one embodiment of the present invention, the depth or height H of the annular grooves  103  is 0.01-0.06 mm, and preferably 0.03 mm. See  FIGS. 11-12 . The height H of 0.03 mm can vary based on the product on which the extruded layers  1  and  2  are to be used. For example, this preferred height can be used for inflatable mattresses. 
         [0042]    A chamfer  114  is provided at a location where the annular grooves  103  transition to the surface of the circular roller body  101 . In this way, the annular groove  103  and the surface of the circular roller body  101  are in natural transition, thereby providing a smooth transition, so that the resulting product has naturally transitioned thickened sections and non-thickened sections, without any sharp corners or edges, while experiencing uniform stress throughout. In a preferred embodiment, the radius R2 of the chamfer  114  is 0.01 mm. Although the adjacent annular grooves  103  are shown herein as being spaced apart from each other in equal distances, the spacing between the adjacent annular grooves  103  can be adjusted and varied depending on the product and application. 
         [0043]      FIGS. 13A-13B  and  14 A- 14 B illustrate the resulting layers  1  and  2 , respectively, that are extruded using the roller  100 . 
         [0044]      FIG. 15  illustrates how high frequency welding is used to weld together thickened sections  1  and  2  of  FIG. 1  according to the present invention. The layers  1  and  2  are placed between a conventional brass/copper mold and an electrode, and then the combined layers  1  and  2  are passed through this space between the mold and the electrode. The same technique and roller  100  can be used to extrude any of the tension members  5  or beams  7  and  9  shown in  FIGS. 16-18 . 
         [0045]      FIGS. 16A-C  illustrate three different ways of welding or joining a tension member  5  to layers  1  and  2 . In  FIG. 16A , both the layers  1  and  2  and the both ends  311  and  411  of the tension member  5  can be provided with thickened sections, and then the thickened ends  31  and  41  are welded to the thickened sections  311  and  411 , respectively. In  FIG. 16B , the tension member  5  is not provided with any thickened ends, so that only the thickened sections  311  and  411  are joined to opposite ends of the tension member  5 . Conversely, in  FIG. 16C , the layers  1  and  2  are not provided with any thickened sections, so only the thickened ends  31  and  41  are joined to the layers  1  and  2  having uniformed thickness. 
         [0046]    The I-Beams  7  and  9  can be used as alternatives to the tension members  5  when joining between the layers  1  and  2 . The I-beams  7  and  9  perform the same function as the tension members. 
         [0047]      FIGS. 17A-C  illustrate three different ways of welding or joining an I-beam  7  to layers  1  and  2 . In  FIG. 17A , both the layers  1  and  2  and the both ends  711  and  712  of the I-Beam  7  can be provided with thickened sections, and then the thickened ends  711  and  712  are welded to the thickened sections  311  and  411 , respectively. In  FIG. 17B , the I-Beam  7  is not provided with any thickened ends, so that only the thickened sections  311  and  411  are joined to opposite ends of the I-Beam  9 . Conversely, in  FIG. 17C , the layers  1  and  2  are not provided with any thickened sections, so only the thickened ends  711  and  712  are joined to the layers  1  and  2  having uniformed thickness. 
         [0048]      FIGS. 18A-C  illustrate three different ways of welding or joining a different type of I-beam  9  to layers  1  and  2 . In  FIG. 18A , both the layers  1  and  2  and the both ends  911  and  912  of the I-Beam  9  can be provided with thickened sections, and then the thickened ends  811  and  812  are welded to the thickened sections  311  and  411 , respectively. In  FIG. 18B , the I-Beam  9  is not provided with any thickened ends, so that only the thickened sections  311  and  411  are joined to opposite ends of the I-Beam  9 . Conversely, in  FIG. 18C , the layers  1  and  2  are not provided with any thickened sections, so only the thickened ends  911  and  912  are joined to the layers  1  and  2  having uniformed thickness. 
         [0049]    The present invention provides the following benefits. First, due to the fact that the thickened sections or parts are limited solely to the locations of the joints, the material throughout the rest of the product can be maintained at a minimum, thereby saving on material cost, and allowing the product to be as lightweight as possible. By locating the joints at the thickened sections or parts, better tensile strength is realized after welding, leading to a more durable product. In addition, the construction and manufacturing process are kept as simple as possible. 
         [0050]    While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.