Abstract:
Fasteners including male and female assemblies. At least one of the male or female assembly may have a flexible base that flexes to conform to a non-planar mounting surface. The flexible base is bonded to the stud and/or the socket using techniques that provide a high degree of strength to withstand repeated engagement and disengagement of the fastener. Moreover, in certain embodiments the bonding techniques eliminate the need for mechanical means (for example, threads) to secure the stud to the flexible base. Mechanical tests show that the male assembly according to certain embodiments has 62% more strength than known male assemblies.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to fasteners that may be secured to mounting surfaces, and in particular, fasteners comprising a flexible base that may be secured to non-planar surfaces and that offer increased strength over known fasteners. 
     BACKGROUND OF THE INVENTION 
     In a variety of applications, it may be desirable to provide a fastener that can secure a first and second object together. Examples of objects may include a surface of a boat (such as the hull), a vehicle (such as the grill, hood, or cargo area of an automobile), or a hot tub or pool located on a deck or patio. Other examples may include fabric covers, tarps, straps, or bars. Thus, it may be desirable to provide a fastener to secure a cover to the grill of a vehicle, a tarp to the bed of a pick-up truck, or a cover to the hull of a boat. 
     Such fasteners typically comprise a socket and a stud. The socket may include a base portion and a receiving portion protruding from the base. Likewise, the stud may include a base and a protrusion extending from the base. The receiving portion of the socket receives the protrusion of the stud, thus engaging the stud and the socket, preventing separation of the fastener. The socket may be secured to a mounting surface of a first object, and the stud may be secured to a mounting surface of the second object. As used herein, “mounting surface” refers to a surface of the object where the fastener is secured to the object. Thus, the socket may be coupled to the grill of a vehicle, and the stud may be coupled to the fabric cover. It should be understood that the fastener may be reversed, such that the stud is coupled to the grill and the socket is coupled to the fabric cover. For ease of reference, the background section of this disclosure refers to the stud and socket interchangeably as “a fastener component” unless otherwise noted. 
     One technique for coupling the fastener component to the mounting surface involves drilling a hole in the mounting surface and using a screw to clamp the fastener component to the mounting surface. But this technique has a significant disadvantage of damaging the mounting surface by drilling a hole through the surface. Thus, alternative techniques have been developed to avoid damaging the mounting surface. 
     One such alternative technique uses adhesives to secure the fastener component to the mounting surface. For example, the base of the fastener component (which typically has a planar surface) may be coated with a layer of adhesive and then secured to the mounting surface. It may be difficult to provide a strong bond if the mounting surface is curved or otherwise non-planar. Specifically, when coupled, there may be a gap between the planar base of the fastener component and the non-planar mounting surface. The gaps reduce the strength of the bond between the fastener component and the mounting surface. Thus, if the fastener is repeatedly engaged and disengaged over several cycles, then the fastener component may pull apart from the mounting surface. (It should be noted that the same difficulties may be encountered when welding—as opposed to adhering—the fastener component to the non-planar mounting surface.) 
     U.S. Pat. No. 5,797,643, which lists Lloyd Demedash as an inventor (hereinafter, “Demedash”), describes a fastener that purports to couple to non-planar mounting surfaces. Specifically, Demedash describes a “flexible mounting member” that is affixed to the fastener and that deforms to follow the curvature of a non-planar mounting surface. The flexible mounting member has a post that engages with an aperture defined in the fastener, thus securing the flexible mounting member to the fastener. Demedash teaches that the amount of force provided by the post (to secure the flexible mounting member and the fastener) is greater than the amount of force necessary to disengage the fastener (that is, to pull the socket from the stud). Thus, according to Demedash, the flexible mounting member will not detach when the fastener is repeatedly engaged and disengaged over several cycles. Demedash is assigned to FIA, Inc. of Winnipeg, Canada, which makes the STICK A STUD® product that is allegedly a commercialized embodiment of Demedash. 
     But the fastener described by Demedash (and the STICK A STUD® product) have several disadvantages. Most notably, tests performed on the STICK A STUD® product establish that the product fails when subjected to relatively low pull strengths. Additionally, the method of attachment between the flexible mounting member and the fastener requires specific design constraints that may be undesirable. Specifically, the post of the flexible mounting member requires that an aperture be provided in the fastener. It may not necessarily be desirable to provide a fastener with such an aperture. Finally, the post protrudes into the body of the fastener, which may obstruct proper engagement of the socket and stud. 
     Thus, it is desirable to provide a fastener component that couples to a non-planar mounting surface, but at the same time provides a high degree of strength prior to failure, withstands repeated engagement and disengagement of the fastener over several cycles, and also avoids limiting design constraints. 
     SUMMARY OF THE INVENTION 
     Examples described herein include a male assembly for a fastener, the male assembly comprising a rigid stud that is bonded to a flexible base. A layer of adhesive may be provided on the flexible base to thereby secure the male assembly to a mounting surface. If the mounting surface is non-planar, then the flexible base may flex to conform to the non-planar mounting surface. Techniques used to bond the stud to the flexible base provide a high degree of strength to withstand repeated engagement and disengagement of the fastener. Moreover, the bonding techniques may eliminate the need for the post as provided in Demedash to secure the stud to the flexible base. 
     Similarly, some examples include a female assembly comprising a rigid socket that is bonded to a flexible base that may flex to conform to a non-planar mounting surface. Bonding techniques provide a high degree of strength, and may eliminate the need for mechanical means to secure the socket to the flexible base. It is not necessary for a single fastener to include both a male assembly and a female assembly with a flexible base—only one of the assemblies may be provided with a flexible base. 
     Mechanical tests performed on the male assembly show an increase of 62% in strength over the fastener described by Demedash. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure including the best mode of practicing the appended claims and directed to one of ordinary skill in the art is set forth more particularly in the remainder of the specification. The specification makes reference to the following appended figures, in which use of like reference numerals in different features is intended to illustrate like or analogous components. 
         FIGS. 1A-D  are various views of one embodiment of a male assembly of a fastener. 
         FIGS. 2A-E  are various views of one embodiment of a stud according to the male assembly shown in  FIGS. 1A-D . 
         FIGS. 3A-D  are various views of one embodiment of a female assembly of a fastener. 
         FIGS. 4A-E  are various views of one embodiment of a socket according to the female assembly shown in  FIGS. 3A-D . 
         FIG. 5  is a cross-sectional view of a fastener comprising a male assembly and a female assembly according to certain embodiments. 
         FIG. 6  illustrates a male assembly secured to a non-planar mounting surface according to certain embodiments. 
         FIG. 7  illustrates a female assembly secured to a non-planar mounting surface according to certain embodiments. 
         FIG. 8  is a graph showing test results performed on a male assembly according to certain embodiments. 
         FIG. 9  is a graph showing test results performed on a product as described by Demedash. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Certain embodiments of the invention provide a male assembly  10  and a female assembly  40  that may be secured to one another in order to form a fastener  100  (as shown in  FIG. 5 ). The male assembly  10  may include a stud  12  (as shown in  FIGS. 2A-E ) comprising a protrusion  16  extending from a base  14 . As can be seen in  FIG. 2C , the base  14  is generally planar. In the embodiments shown in the figures, the protrusion  16  is shaped like a continuous ring, but it should be understood that in other embodiments, the protrusion  16  may have other shapes, and may or may not be continuous. The protrusion  16  may be defined by a sidewall  18 . As shown in the cross-sectional view of  FIG. 2E , in some embodiments the sidewall  18  is generally “U-shaped” (although the sidewall  18  is not necessarily symmetrical) and defines a pocket  20  inside the U-shape, such that the protrusion  16  is “hollow.” A central surface  22  is positioned in the middle of the circular-shaped protrusion  16 . 
     The female assembly  40  may include a socket  42  (as shown in  FIGS. 4A-E ) comprising a receiving portion  46  and a base portion  44 . In the embodiments shown in the figures, the receiving portion  46  has a larger diameter than the base portion  44 . The receiving portion  46  extends from the base portion  44  and is defined by a sidewall  52 . A corner  48  is formed where the base portion  44  and the receiving portion  46  meet. In the embodiments shown in the figures, the receiving portion  46  and the base portion  44  are both circular, but it should be understood that in other embodiments, the respective portions  44 ,  46  may have other shapes. As can be seen in  FIG. 4C , the base portion  44  has a bottom surface  50  that is generally planar. 
     As shown in  FIG. 5 , the receiving portion  46  of the socket  42  receives and secures the protrusion  16  of the stud  12  with a mechanical interference fit, thus engaging the stud  12  and the socket  42 , preventing separation of the fastener  100 . In certain embodiments, the receiving portion  46  comprises a retainer  54  proximate the inner surface of the sidewall  52 . The retainer  54  may have a smaller diameter than the receiving portion  46 , such that the retainer  54  may provide a more secure mechanical interference fit with the protrusion  16  of the stud  12 . It should be understood that the retainer  54  is only optional and is not required. 
     The stud  12  and/or the socket  42  may be formed of a variety of materials, such as metals (including but not limited to stainless steel) or any rigid or semi-rigid plastic. If made of metal, the stud  12  and socket  42  may be stamped into their final forms. If made of plastic, the stud  12  and socket  42  may be injection die molded. 
     In certain embodiments, the stud  12  is coupled to a flexible base  30  to form a male assembly  10  (as shown in  FIGS. 1A-D ). Similarly, in certain embodiments the socket  42  is coupled to a flexible base  60  to form a female assembly  40  (as shown in  FIGS. 3A-D ). Each flexible base  30 ,  60  may flex to conform to a non-planar mounting surface  110 . Thus, as shown in  FIG. 6 , the flexible base  30  of the male assembly  10  is flexed to conform to the non-planar mounting surface  110  (here, a section of pipe). A layer of adhesive  36  on the bottom surface  32  of the flexible base  30  secures the male assembly  10  to the mounting surface  110 . Similarly, in  FIG. 7 , the flexible base  60  of the female assembly  40  is flexed to conform to the surface  110 . A layer of adhesive  66  on the bottom surface  62  of the flexible base  60  secures the female assembly  40  to the mounting surface  110 . It should be understood that it is not necessary for a single fastener  100  to include both a male and female assembly  10 ,  40  with a flexible base  30 ,  60 . Rather, a fastener  100  may be provided with only one assembly (either the male  10  or female  40 ) that includes a flexible base. 
     Methods of manufacturing the assemblies  10 ,  40  will now be described. For ease of reference, this discussion refers to the manufacture of the male assembly  10 , although it should be understood that the same general methods may be used for the female assembly  40 . 
     First, the stud  12  is pre-treated with a bonding or priming agent in order to help strengthen the bond between the stud  12  and the flexible base  30 . One such bonding agent is a dilute solution of moisture-reactive materials in VM&amp;P naphtha. The Dow-Corning Company produces such a material, under the name of Dow-Corning Prime Coat #2260. In certain embodiments the stud  12  is treated with the bonding agent for at least fifteen minutes, after which time the excess bonding agent is drained or wiped clean from the stud  12 . 
     In general, the flexible base  30  may be made of silicone, rubber, or any flexible plastic. In one non-limiting embodiment, the flexible base  30  is made from a blend of Dow-Corning TR-70 and Q-44768 elastomer materials, with their specific ratios being adjustable depending upon the specific application. If desired, a catalyst may be used to form the flexible base  30 . One possible catalyst is an organic peroxide, which may be provided in different forms depending upon whether the flexible base  30  is clear or tinted. For a clear flexible base  30 , the catalyst may be an organic 100% peroxide in liquid form, having the chemical composition 2,5 dimethyl-2,5 di/t-butylperoxy/hexane. For a tinted flexible base  30 , the above catalyst may be provided in only a 50% peroxide powder form. Either of the above catalysts may be supplied by Dow-Corning Company, as DBPH-100 for clear elastomers, or as DBPH-50 for colored or tinted elastomers. Alternative catalytic agents include platinum and tin compounds. When the catalyzing process has been completed, the material that comprises the flexible base  30  will be in the form of a resilient solid. In certain embodiments, the material is formed in sheets. If desired, multiple layers or thicknesses may be used to create the male assembly  10 . 
     Next, the material that comprises the flexible base  30  may be bonded to the stud  12 . In one embodiment, a suitable container or holder (similar to a mold) may be provided to assist in the bonding process. If desired, the mold may have a “stud portion” to receive the stud  12 , and a “base portion” that is shaped to form the flexible base  30 . The base portion may have a profile that forms a flexible base  30  with a particular shape or size. For example, as shown in  FIG. 1D , the top surface of the flexible base  30  is angled relative to the stud  12 . Thus, the base portion of the mold may have a profile to produce this particular angle. In other embodiments, the flexible base  30  may have a different angle, may not be angled, or may be dome-shaped, etc. The mold may produce a flexible base  30  having any desired shape or size. 
     The stud  12  may be placed inside of the stud portion of the mold, with the base  14  of the stud  12  facing the base portion of the mold. The material that comprises the flexible base  30  may be placed directly on top of the base  14  of the stud  12 , within the base portion of the mold. Next, a heated plate or the like may be placed atop the material that comprises the flexible base  30 , and pressure may be applied to the plate to press the material onto the stud  12 . In certain embodiments, the curing temperature is approximately 340° F., and the plate is left in place for approximately two minutes. The heat and pressure process causes the material that comprises the flexible base  30  to melt. The melted material flows within the base portion of the mold, forming the particular shape of the flexible base  30 . If the stud  12  is provided with pockets  20 , then the melted material may flow into the pockets  20 , forming extensions  34  to fill the pocket  20 . The heat and pressure thus bond the flexible base  30  to the stud  12 , forming the male assembly  10 . Next, the plate may be removed from the male assembly  10  and excess material that comprises the flexible base  30  may be trimmed. 
     Due to the bonding of the flexible base  30  and the stud  12 , it is not necessary to provide a post in the flexible base  30  as described by Demedash. All of the bonding is accomplished by the application of heat and pressure, and if desired, pre-treating of the stud  12  with a bonding agent. Increased bonding strength (in particular, increased shear strength) may also be provided in embodiments having extensions  34  that fit within pockets  20 . 
     A layer of adhesive  36  may be affixed to the bottom surface  32  of the flexible base  30  to thereby secure the male assembly  10  to the mounting surface  110 . The adhesive may comprise either a non-reactive adhesive or a reactive adhesive. The type of adhesive to be used may be determined by the size of the substrate and/or the mounting surface  110 . One of skill in the art would be aware of many suitable adhesives, but one non-limiting example is the VHB® Tape, sold by 3M Company, which is made with a layer of acrylic foam and a layer of adhesive. The VHB® Tape is offered with several adhesive types, including multi-purpose acrylic (that bonds to metals, glass, and high and medium surface energy plastics and paints), modified acrylic (that bonds to low surface energy plastics and paints, such as powder-coated paints), or low temperature appliable acrylic (that bonds down to 32° F.). The VHB® Tape is also offered with several foam types, each having different levels of conformability. If desired, the bottom surface  32  of the flexible base  30  may be pre-treated with a bonding agent, or may be mechanically deformed (such as with a sander) prior to application of the adhesive  36 . The adhesive  36  may simply be pressed onto the bottom surface  32  of the flexible base  30  under atmospheric temperature and pressure. That is, no heated platen and/or extreme pressures are needed to bond adhesive  36  to the flexible base  30 . Similarly, no heated platen and/or extreme pressures are needed to bond the adhesive  36  to the mounting surface  110 . (If desired, adhesive may also be applied directly to the mounting surface  110 .) 
     Although the preceding discussion of the methods of manufacture referred to the male assembly  10 , it should be understood that the same methods may be used for the female assembly  40 . In the embodiments shown in  FIG. 3 , the socket  42  is provided with a corner  48  where the base portion  44  and the receiving portion  46  meet. When the material that comprises the flexible base  60  melts due to the application of heat and pressure, the material flows around the base portion  44 , into the corner  48 , and around at least a portion of the receiving portion  46 . The amount of surface area between the flexible base  60  and the socket  42  (specifically, around the base portion  44 , the corner  48 , and at least a portion of the receiving portion  46 ) provides increased shear strength for the female assembly  40 . 
     When the fastener  100  is secured to the mounting surface  110  and put into use, there are three possible points of “failure” of the fastener—specifically, between (1) the adhesive  36  and the mounting surface  110 ; (2) the adhesive  36  and the bottom surface  32  of the flexible base  30 ; and (3) the stud  12  and the flexible base  30 . The term “point of failure” means that the components separate or break apart at that point. For example, if the fastener  100  failed between the adhesive  36  and the mounting surface  110 , it means that the adhesive  36  pulled or ripped away from the mounting surface  110 . In the optimal design of a fastener, the force that will cause a failure is significantly greater than the force of engaging and disengaging the fastener  100 . In other words, it is desired that the fastener will not fail when it is engaged and disengaged, and in particular, that the fastener will not fail over repeated cycles. It has been found that embodiments of fasteners  100  described herein provide increased strength at each of these points of failure. 
     Specifically, the STICK A STUD® product (which is allegedly a commercialized embodiment of Demedash) and a product according to certain embodiments described herein (the “applicant&#39;s product”) were compared in strength tests. In one test, an Instron Model 4444 force gauge (“Instron”) was used in a direct pull strength test of both the STICK A STUD® product and the applicant&#39;s product. The testing configuration for both products was the same. First, the male assembly of the fastener (the female assembly component was not tested) was secured to a rod. Then the upper clap fixture of the Instron was used to clamp the stud of the assembly. Each assembly was pulled by the Instron over known distances, as reflected in  FIG. 8  (pull strength test results of the applicant&#39;s product) and  FIG. 9  (results of the STICK A STUD® product). The black triangles on each Figure indicates the point that the respective product failed. As shown in  FIG. 8 , the applicant&#39;s product was pulled a distance of approximately 0.3 inches before it failed at a load of 30.8 pounds of force (lbf). In contrast, the STICK A STUD® product was only pulled a distance of approximately 0.08 inches before it failed at a load of 11.6 lbf. These test results show that the applicant&#39;s product exhibits 62% higher strength than the STICK A STUD® product. 
     The test results also highlight differences between the designs of the two products. In the applicant&#39;s product, the point of failure was between the adhesive  36  and the mounting surface  110 . In the STICK A STUD® product, the point of failure was between the post of the flexible mounting member and the aperture defined in the fastener. A point of failure between the adhesive  36  and the mounting surface  110  (as in the applicant&#39;s product) is preferred such that no part of the assembly  10  is left behind on the mounting surface  110 . For example, because the STICK A STUD® product failed between the flexible mounting member and the fastener, the flexible mounting member was left secured to the mounting surface. Leaving components secured to the mounting surface is undesirable because those components must be removed, which may be difficult. 
     The foregoing is provided for purposes of illustration and disclosure of embodiments of the invention. It will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, it should be understood that the present disclosure has been presented for purposes of example rather than limitation, and does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.