Abstract:
An article of cookware is assembled by the riveted attachment of a handle. Novel rivets are first attached from the interior of the cookware article via a flush hole such that the deformation of the cookware article around the rivet locks the rivet to the cookware article yet leaves the rivet head flush with the interior surface of the cookware article. The handle is subsequently attached by deforming the opposite end of the rivet.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     None 
     BACKGROUND OF INVENTION 
     The present invention relates to cookware vessels, in particular to cookware vessels having rivet attached handles. 
     Cookware vessels, such as pots pans and the like require handles so that they can be moved and manipulated by the cook. While such cookware vessels can be fabricated out of glass, ceramic material, and glass ceramics the preferred materials of construction for the greatest versatility are metals. Likewise it is desirable that the handle is also metallic, or at least has the principle structural component or the flange portion that is connected directly to the cooking vessel is formed of metal. While it is possible to form a cookware vessel with an integral handle by drawing and deforming a pliable metal sheet, the more common method is to first form the fluid containing cooking vessel and to then attach the handle. This allows for the handle to be constructed from a wider variety of shapes, as well as the use of multiple and different materials than the cookware vessel itself. As the handle must support the weight of the cookware vessel and the contents, which can be considerable if it is full of liquid, the bond between the handle and the cooking vessel must be strong and durable. While it is possible to weld a handle onto the outside of the cookware vessel, attachment with multiple rivets is the preferred assembly method as this process can be highly automated and produces a uniformly consistent and aesthetic appearance in each product produced. While rivets can be avoided in some instances by spot welding a handle to the side wall of a cooking vessel, it is desirable to use a multiple component handle to cover the spot weld location on the outside of the pan. Thus, frequently for light weight thin aluminum cookware a separate handle is attached by one or more screws to a flange that is spot welded to the outside of the cooking vessel wall. The handle will frequently have a canopy that extends over the sport welded flange, thus covering up the welding marks. Such screwed on handles have a less durable appearance, with the potential for the screws to loosen with abuse and poor attention to maintenance. 
     Although rivet connected handles are ideally suited for heavier duty cookware, in part because they convey the impression of durability to the consumer, they do have a number of drawbacks. The major drawback to rivets is that the rivet heads protrude into the interior of the cooking vessel. Though many consumers have grown accustomed to this appearance, the inward extending portion of the rivet can be more difficult to clean as for example when the inside of the cookware has a fluoropolymer non-stick coating and the rivets do not. In addition, debris can accumulate and char at the margin between the rivet and the interior cooking vessel surface, requiring extra care and more frequent attention by the consumer or professional cook in cleaning. 
     In another embodiment of the invention, the rivets  10  are constructed so as to be non-protruding when attached to the sidewall  108  of the cookware vessel  100 . Each of such rivets  10  may be described as generally comprising a cylindrical shank portion  11 , an inverted conical portion  16  and an annular notch  13  at the margin there between, as shown in  FIG. 1A . The inverted conical head  16  extends outward from the annular notch  13  to the proximal end of head  10   a  of rivet  10 . In a more preferred embodiment of the invention, the portion of shank  11  between the annular notch  13  and the distal end  10   b  of rivet  10  is at least partially threaded with helical screw threads  14 . The purpose of the threads  14  is best understood with reference to the embodiment described with respect to  FIG. 1C . 
     Accordingly, it is one object of the invention to provide a durable means for attaching cookware handle to the sides and lids of cookware, having the strength of rivets, yet that is aesthetically improved with at least a minimized appearance of the rivets. 
     It is a further object of the invention to provide cookware that is easier to clean as well as more sanitary. 
     SUMMARY OF INVENTION 
     In the present invention, the first object is achieved by providing a locking rivet that comprises a substantially cylindrical shank portion and an inverted cone portion extending outward from the shank portion having an inward extending annular notch disposed within the cylindrical shank portion and the junction with the inverted cone portion. 
     A second object of the invention is achieved by providing a locking rivet according to the first object that also comprises helical external threads about at least a part of the shank portion. 
     Another object of the invention is achieved by the method of first providing a fluid containing vessel, then forming holes in the sidewall of a fluid containing vessel and providing rivets having a tapered head and notched sides at the root of the taper and shank portion of the rivet. The shank portion of the rivets are then inserted into the holes formed in the sidewall of the fluid containing vessel from the interior of the vessel so as to deform the portion of the sidewall surrounding each hole such that it flows into the notched sides of the rivet thereby mechanically interlocking the rivet and the sidewall of the cooking vessel. Thereafter a handle that comprises a flange portion and the plurality of holes with a complementary pattern to the rivets, is inserted over the outward extending or shank portion of the rivets. Thereafter shank portion of the rivets that extend through the holes of the flange are deformed such that they flatten and expand past the margins of the holes thereby locking the handle to the cookware vessel. 
     The above and other objects, effects, features, and advantages of the present invention will become more apparent from the following description of the embodiments thereof taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a cross-sectional elevation of a rivet prior to being inserted into the hole in the sidewall of the cooking vessel. 
         FIG. 1B  is a cross-sectional elevation of the rivet of  FIG. 1A  inserted into the flush hole formed in the sidewall of the cooking vessel. 
         FIG. 1C  is a cross-sectional elevation of the rivet showing the outward extending portion protected prior to an anodizing treatment. 
         FIG. 1D  is a cross-sectional elevation of the rivet with the handle flange inserted thereon prior to final attachment. 
         FIG. 1E  is a cross-sectional elevation through the rivet and handle flange after final attachment of the handle to the sidewall of the cooking vessel, 
         FIG. 2A  is a perspective view of the rivet in  FIG. 1E  from the inside of the cooking vessel 
         FIG. 2B  is a perspective view of the rivet of  FIG. 1E  from the outside or handle flange portion of the cooking vessel. 
         FIG. 3A  is a cross-sectional elevation of the rivet in an alternative embodiment of the invention with the handle flange inserted thereon prior to final attachment. 
         FIG. 3B  is a cross-sectional elevation through the rivet and handle flange of the embodiment in  FIG. 3A  after final attachment of the handle to the sidewall of the cooking vessel. 
         FIG. 4A  is a plan cross-section view through the flange, rivets and sidewall of a partially assembled cookware vessel according to another embodiment of the invention. 
         FIG. 4B  is an elevation of the flange section shown in  FIG. 4A  to illustrate a preferred configuration for the holes in the flange. 
         FIG. 5A  is a plan cross-section view through the flange, rivets and sidewall of a partially assembled cookware vessel according to another alternative embodiment of the invention. 
         FIG. 5B  is an elevation of the flange section shown in  FIG. 5A  to illustrate an alternative configuration for the holes in the flange. 
         FIG. 6A  is a plan cross-section view through the flange, rivets and sidewall of a partially assembled cookware vessel according to an additional embodiment of the invention. 
         FIG. 6B  is an elevation of the flange section shown in  FIG. 6A  to illustrate a preferred configuration for the holes in the flange. 
         FIGS. 7A , B and C are a series of plan cross-sections showing an alternative embodiment for assembling the handle flange with the rivets. 
         FIG. 8  is a cross sectional elevation of another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-8 , wherein like reference numerals refer to like components in the various views, there is illustrated therein a new and improved cookware vessel with flush rivet system, generally denominated  100  herein. 
     In accordance with a first embodiment of the present invention a cookware vessel  100 , of which the relevant portions are shown in  FIG. 2 , comprises a handle  120  with a flange portion  125  attached to sidewall  108 . The cookware vessel  100  comprises a fluid containing a portion  110  having a bottom  105  and substantially upright surrounding sidewalls  108 . The handle  120  is attached to the cookware vessel with non-protruding rivets  10  via flange  125 . Rivets  10  penetrate through the co-aligned holes  112  and  126  that are formed in the sidewall  108  and handle flange  125  respectively. The rivets  10  do not protrude into the interior of the cookware vessel, being substantially flush with the interior sidewall  108   
     In another embodiment of the invention, the rivets  10  are constructed so as to be non-protruding when attached to the sidewall  108  of the cookware vessel  100 . Each of such rivets  10  may be described as generally comprising a cylindrical shank portion  11 , an inverted conical portion  16  and an annular notch  13  at the margin there between, as shown in  FIG. 1A . The inverted conical head  16  extends outward from the annular notch  13  to the proximal end  10   a  of rivet  10 . In a more preferred embodiment of the invention, the portion of shank  11  between the annular notch  13  and the distal end  10   b  rivet  10  is at least partially threaded with helical screw threads  14 . The purpose of the threads  14  is best understood with reference to the embodiment described with respect to  FIG. 1C . 
     Another embodiment of the invention is the method of inserting the rivets  10  to couple the handle flange  125  to the cookware vessel sidewall  108 . This method is best understood in reference to the intermediate stages of construction shown in  FIGS. 1A-E . 
     As shown in  FIG. 1A  initially cookware vessel  100  has a sidewall  108  with preferably a plurality of flush or straight sided through holes  112  for receiving a plurality of rivets  10 . The rivet  10  is generally first inserted into hole  112  from the inside of the inside of cookware vessel such that side  10   a  faces the inner fluid containing portion. 
     In the step shown in  FIG. 1B , rivet  10  has been inserted in flush sided hole  112  and impact bonded such that surface  10   a  become flush with the inner cooking surface on wall  108 . When this occurs a portion  112   a  of the sidewall adjacent the hole  112  flows into the notch portion  13  of rivet  10 , locking the rivet  10  to the sidewall  108 . At this stage the handle can be attached in an additional step of inserting the rounded end  10   b  of the rivet into a through hole  126  in the handle flange  125 . The protruding end  10   b  of rivet  10  is now impacted to cause it to deform around hole  126 , thus locking the handle to the vessel  110  to complete the article of cookware  100 . After this step it is possible to attached handle  120  via flange  125  by first using the additional step illustrated in  FIG. 1D , i.e. aligning the holes  126  in flange  125  with the outward extending portion  10   b  of rivets  10 . Then, as shown in  FIG. 1E , the end of the rivet  10   b  is impacted with a tool to deform it to  10   b ′, thus compressing it into hole  126  so that the handle and fluid containing portion of the cooking vessel  110  are firmly attached and coupled together. 
     A more preferred embodiment is shown in  FIGS. 1C-1E  in which rivet  10  is aluminum, as is vessel  110 . In  FIG. 1C  a protective metal cap  140  is screwed onto the threads  14  of rivet  10  to cover end  10   b . The next step in this preferred process is an anodizing treatment of the cooking vessel  110  and the inner unprotected face of rivet head  10   a  of rivet  10 . Anodizing the face of rivet head  10   a  and the cooking vessel  110  has several advantages. First, the interior of the vessel has a more flush uniform appearance making the inner rivet essentially disappear so that the inside is readily cleaned after cooking. Unlike convention methods of riveting handles to cookware after anodizing treatment, by first attaching the rivet  10  to the cooking vessel  110  enable the anodizing of the rivet surface on inward facing portion of head  10   a . More significantly, when a non-stick organic coating, such as a fluoropolymer coating, is applied over the interior of the cooking vessel  110 , both the rivet and the cooking vessel  110  both have same anodized finish such that the fluoropolymer coating will durably adhere to the entire cooking surface. In contrast to rivets that are not anodized aluminum or added after the fluoropolymer coating, the resulting cookware article  100  will be easier to clean and maintain. It is more preferable that the cap  140  preferably has a notch  141  for attaching a titanium or other oxidation resistant metal electrode material to supply electrical current to the entire vessel  110  during the anodizing process. 
     Accordingly, as shown in  FIG. 1D , such anodizing step with protective cap  140  in place results in an aluminum oxide or alumina coating layer  160   a  on the front face  10   a  of rivet  10  as well as the inside surface  108   a  and outside surface  108   b  of sidewalls  108 . However the threads  14  and protected rear portion  10   b  of rivet  10  are not anodized. Thus, upon joining the flange  126  as shown in  FIG. 1E , impacting the rear portion  10   b  of rivet  10  causes it to compress into hole  112 ″ to secure the flange to the cooking vessel wall. It should be noted that had portion  10   b  become anodized, it is expected that it would be more difficult to properly compress. It should be noted that the screw flights  14 ′ collapse and essentially disappear under flange hole  126  when the rivet end  10   b  is compressed. 
     In the alternative embodiment illustrated in  FIGS. 3A and 3B , the rivet  10  has been inserted into sidewall  108  and at least the interior of the vessel  110  anodized as described with respect to  FIG. 1A-C  above. However, the flange  125  portion of handle  120  rather than having flush holes in the previous embodiment now has beveled or countersunk holes. Specifically, the exterior face of the flange  125  is countersunk  113  about the hole  126 . 
     Thus, upon joining the flange  125  by impacting the rear portion  10   b  of rivet  10 , as shown in  FIG. 3B , causes it to flat or mushroom into end  10   b ′ such that portion  23  fills the fills bevel  113  securing the flange to the cooking vessel wall. 
       FIG. 4-7  illustrate alternative embodiments of the invention wherein either the holes  126  in the flange  125  or the sidewall  108  are modified in various ways to facilitation mounting the flange  125  over the outward extending portion  10   b  of the rivets  10 . 
       FIG. 4  is intended to illustrate a preferred configuration for the flange portion  125  of the handle  120  to facilitate attachment of the handle  120  after the rivets  10  and  10 ′ have been inserted and attached to the wall  108  of the cookware vessel  100 . As illustrated in the plan view in  FIG. 4A  for rivets  10  and  10 ′, it should be understood that it is conventional for each rivet to be inserted through the sidewall  108  of the cooking vessel  100  and then into the flange  125  to be disposed with its principal access perpendicular to the tangent to the vessel surface  110  at the point of attachment. However, since it is preferred to attach both rivets  10  and  10 ′ to the interior of the vessel before attaching the flange  125 , it should be appreciated from  FIG. 4A  that one of holes  126  or  126 ′ will be difficult to insert over the corresponding rivet  10  and  10 ′ respectively. 
     However, first it should be appreciated that this limitation depends in large part on the curvature of the cookware vessel and the separation of the right and left rivet holes on the flange from the center of the flange. To the extent that at least one rivet can be considerably narrower than the holes in the flange and/or the flange has some flexibility these embodiments may not be necessary in all cases. 
     Thus, with  FIG. 4A  illustrating the embodiment wherein rivets  10  and  10 ′ are not oriented parallel, but away from each other by angle +/−α (with respect to the orthogonally extending line taken at the intermediate tangent to the wall  108 ), at least hole  126  that receives the left rivet  10  is disposed at angle 2α from the rivets central axis so that the handle flange  125  can be inserted over both the right  10 ′ and left  10  rivets. Thus, the right most hole  126 ′ in flange  125  is cut parallel to line pairs  401 ′ disposed at angle α. However, as it is preferable to assemble the flange after the attachment of the right  10 ′ and left  10  rivets, the left hole  126  in handle flange  125  is cut so that the end  10   b  of rivet  10  will clear. Thus, the projection of the cut for rivet  10  is also a pair of parallel line  401 , which are mutually parallel to line pair  401 ′. Line pair  401  is disposed at an angle of  2   a  with respect to the principle axis of the left rivet  10 . It should be thus appreciated that because hole  126  in  FIG. 4B  is cut at an angle, it has an elliptical shape at the intersection with the exterior of the sidewall. This is shown in  FIG. 4B  wherein the left hole  126  is elliptically widened to provide sufficient clearance so that the handle  120  and flange  126  can be laterally mounted to the sidewall  108  in a single step. 
       FIGS. 5A  and B illustrate an alternative orientation for holes  126  and  126 ′ intended to accommodate rivets  10  and  10 ′ respectively. Both holes, the edges of which are represented by parallel line pairs  501  and  501 ′, are cut parallel to the surface normal to the cookware vessel wall at the position intermediate to the right  10 ′ and left  10  rivets. Thus, rivets  10 ′ and  10  are not disposed orthogonally with respect to the tangent at the point of attachment with the vessel sidewall  108 , but rather parallel to the main or central portion of the handle  120  that extends orthogonally from the tangent to the wall taken intermediate between each of flanges holes  126  and  126 ′. 
       FIGS. 6A  and B illustrates yet another alternative embodiment wherein the rivets  10  and  10 ′ are oriented as in  FIG. 4A , however each of holes  126  and  126 ′ has bevels  113  and  113 ′ respectively surrounding it. In this embodiment at least hole  126  that receives the left rivet  10  is disposed at angle 2α from the rivets central axis so that the handle flange  125  can be inserted over both the right  10 ′ and left  10  rivets. Thus, the right most hole  126 ′ in flange  125  is cut parallel to line pairs  601 ′ disposed at angle α. However, as it is preferable to assemble the flange after the attachment of the right  10 ′ and left  10  rivets, the left hole  126  in handle flange  125  is cut so that the end  10   b  of rivet  10  will clear. Thus, the projection of the cut for rivet  10  is also a pair of parallel line  601 , which are mutually parallel to line pair  601 ′. Line pair  601  is disposed at an angle of 2α with respect to the principle axis of the left rivet  10 . It should be thus appreciated that because hole  126  in  FIG. 6B  is cut at an angle, the surrounding bevel  113  will have an elliptical shape at the intersection with the exterior of the sidewall. This is shown in  FIG. 6B  wherein the left hole  126  is elliptically widened to provide sufficient clearance so that the handle  120  and flange  126  can be laterally mounted to the sidewall  108  in a single step. Further, as the left most hole  126  has a greater bevel area to be filled, it is preferable that the left most rivet is slightly longer to provide a more uniform fill and appearance between the left and right rivets. 
     Alternatively, the rivets  10  and  10 ′ can be attached to the inside of the cooking vessel wall  108  after flange  125  is placed up to align holes  112  and  126 . One non-limiting example of such an embodiment is illustrated in  FIG. 7A-C . In the first stage,  FIG. 7A , the right rivet  10 ′ is inserted in the right hole in the vessel sidewall  108  and secured to the sidewall  108  as described with respect to the  FIG. 1A-E . Next, the flange  125  of handle  120  is brought up against the exterior sidewall such that the rivet  10 ′ is inserted in the right hole, with the left holes  112  and  126  being empty ( FIG. 7A ). Thereafter, as shown in  FIG. 7B , the left rivet  10  is inserted through the left hole  112  in the sidewall  108  and the left hole  126  in flange  125 , and impacted from the inside of the cookware vessel  110  so that the rivet  10  locks into the sidewall. With both the right  10 ′ and left  10  rivets thus installed in the sidewall  108  and passing though the right  126 ′ and left  126  holes in flange  125 , the opposite side  10   b  of both rivets  10 ′ and  10  can be impact such that they compress and fills the bevel  113 ′ and  113  respectively, this result being shown in  FIG. 7C . 
       FIG. 8  illustrates in cross-sectional elevation another embodiment of the invention wherein the non-stick coating layer  170  is applied over at least the interior surface  108   a  includes at least one rivet  10 , both of which are coated with a continuous aluminum oxide or alumina layer formed by anodizing the inner cooking vessels walls at  108  and the head of the rivet  160   a . Having both the interior of the cookware article and the internal face of the rivet covered with the continuous aluminum oxide coating further conceals the rivet interface, as well as improves the adhesion of the nonstick coating layer  170 . Non-stick refers to a cooking surface that resists food sticking to it without the aid of oils or fats. Such coating typically include one or more layers of fluoro-polymers or fluoro-silicone polymers or other coating material with a low surface energy. 
     While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be within the spirit and scope of the invention as defined by the appended claims.