Abstract:
A method and apparatus for transferring formed adhesive elements from a reservoir ( 30 ) containing plural formed adhesive elements ( 12 ) to a bonding part attachable to a glass surface or other substrate through the use of adhesives. Transfer of the formed adhesive element to the bonding part ( 14 ) is accomplished by use of a vacuum tool ( 10 ) having a vacuum outlet, an internal plenum, and a series of vacuum lines formed in an adhesive element holding face. The vacuum tool is positioned over a reservoir of formed adhesive elements. Once the formed adhesive elements have been captured by the vacuum tool ( 10 ) the tool is used to place them into contact with the heated bonding part ( 14 ) directly or indirectly by intermediate placement onto a matrix ( 60 ) having a plurality of ejector pins ( 72 ) movably fitted therein. The ejector pins move the formed adhesive elements into position against the bonding part.

Description:
TECHNICAL FIELD 
     The disclosed invention relates to a bonding part attachable to a glass surface or other substrate through the use of adhesives. More particularly, the disclosed invention relates to a method and apparatus for transferring a prepared adhesive element, such as a structural polyurethane, epoxy or other basic for an adhesive, pressed from a powder to an adhesive tablet, from a supply reservoir of prepared adhesive elements to a bonding part made of any one of several materials including metal, glass, ceramics, plastics, wood and composites for attachment to another component such as a glass surface or to another substrate made of materials such as metal, ceramics, plastics, wood and composites. 
     BACKGROUND OF THE INVENTION 
     Attachment of a first component to a second component for any of a variety of applications may be made by any of several known methods of fastening, including mechanical or chemical fastening. Mechanical fastening, while often practical and reliable, is not always usable for every application. For example, where a first component is being attached to a second component and it is not desirable or practical to drill into or otherwise modify the second component for mechanical attachment, chemical fastening is the only other alternative. This is the case where, for example, a component is to be attached to a glass surface or other substrate (the second component). An example of a component-to-glass arrangement may be seen in the automotive industry where a rear view mirror or a metal hinge needs to be attached to a glass surface. Other examples of component-to-glass attachment needs exist such as in home and office construction. 
     A solution to the bonding challenge was introduced in the form of an adhesive applied between the part to be attached (the bonding part) and the substrate to which the bonding part was attached. The adhesives have been applied in several ways. 
     According to one known approach the adhesive is applied to the bonding part by dosing with nozzles and spraying the adhesive onto the bonding part. While this process can be easy and often inexpensive, it suffers from the need to frequently clean the nozzles in order to maintain a desired level of consistency in the actual spraying from part to part. In addition, the sprayed adhesive tends to be sticky, thus resulting in the possibility that the bonding part will come into contact with another object between the time of the spraying of the adhesive and the actual attachment of the bonding part to the substrate. 
     According to another known approach a double-sided tape is applied to the bonding part. According to this approach a release layer is removed from one side of the tape and the tape is applied to the bonding part. The release layer on the other side of the tape is left in place until the bonding part is ready for attachment to the substrate. This approach offers advantages in that it is usable at room temperature and the adhesive for contact with the substrate is not exposed until needed. Furthermore, the adhesive does not require an adhesion promoter. However, while the release layer protects against the adhesive from being inadvertently attached to a surface, it also adds an inconvenient step in the process of attachment of the bonding part to the substrate in that the layer must be removed prior to attachment. The release layer may also tear resulting in a portion of the layer being left behind on the adhesive surface and creating the potential for imperfect adhesion of the bonding part to the substrate. The step of attaching the double-sided tape to the bonding part is also complicated by the fact that this arrangement of structural adhesives can only be used for in-line assembly in which the bonding part, the double-sided tape and the substrate pass through a heater such as an autoclave to achieve full bonding performance. 
     A third and more attractive method is to provide the bonding part with a formed adhesive element such as a tablet already in position prior to shipment of the bonding part to the end-user. This arrangement is attractive as it results in a bonding part that is ready to bond with no requirement that the end user attach the adhesive tablet to the bonding part. However, it may be that the end user wishes to apply the tablet at its facility and according to its own schedule and arrangement. In such a case the concept of a pre-applied adhesive such as the bonding tablet already fitted to the bonding part may not be the optimal choice. 
     Accordingly, as in so many areas of fastener technology, there is room in the art of bonding parts for an alternate approach to the manufacture of bonding parts. 
     SUMMARY OF THE INVENTION 
     The disclosed invention provides a method and apparatus for the transfer of a prepared adhesive element from a supply reservoir to a bonding part in a practical and efficient way. The formed adhesive element may be conveniently attached to the bonding part by the end-user prior to attachment of the bonding part to the substrate. In order to attach the formed adhesive element to the bonding part according to the disclosed invention, the bonding part is heated and then is moved in position relative to the formed adhesive element. As an alternative arrangement, the bonding part may be used without heating at room temperature. The bonding part is then moved into a pre-contact position relative to the formed adhesive element. Thereafter the bonding part is moved into contact with the formed adhesive element, or the adhesive elements are pushed with ejector pins against the adhesive coating surface of the bonding part. The bonding part, now having the formed adhesive element attached, is ready for attachment to the substrate. One or more formed adhesive elements may be attached to the bonding part. 
     Attachment of the formed adhesive element to the bonding part is accomplished by use of a vacuum tool having a vacuum outlet, an internal plenum, and a series of vacuum lines formed in an adhesive element holding face. The vacuum tool is positioned over a reservoir of formed adhesive elements. The reservoir may have multiple layers of formed adhesive elements or may have a single layer. If the reservoir has plural layers it may be fitted with a plenum and air lines to help lift the formed adhesive elements to move them into contact with the adhesive element attachment face of the vacuum tool. 
     Once the formed adhesive elements have been captured by the vacuum tool the tool is used to place them into contact with the heated bonding part directly or indirectly by intermediate placement onto a matrix having a plurality of ejector pins movably fitted therein. 
     In the event that the intermediate method of attachment is used, the vacuum tool releases the formed adhesive elements into a plurality of apertures formed in the surface of the matrix by switching off the vacuum. Pressure can be used to eject the formed adhesive elements. The matrix has channels extending from the apertures within which ejector pins are reciprocatingly positioned. The apertures have shoulders at their bases that prevent the formed adhesive elements from passing through the channels. The ejector pins can be guided in the matrix plate or in a plate underneath the matrix plate. Vacuum draws in the formed adhesive element into the formed adhesive holding apertures. 
     Once the formed adhesive elements are in position on the matrix the heated bonding part is positioned thereover and the ejector pins push the formed adhesive elements into contact with the heated bonding part. 
     Other advantages and features of the invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of this invention, reference should now be made to the embodiments illustrated in greater detail in the accompanying drawings and described below by way of examples of the invention wherein: 
         FIG. 1  is a sectional view of a vacuum tool for transferring the formed adhesive element shown in position above the reservoir of formed adhesive elements; 
         FIG. 2  is a view similar to that of  FIG. 1  in which the vacuum tool has been moved into contact with some of the formed adhesive elements of the reservoir; 
         FIG. 3  is a view similar to that of  FIGS. 1 and 2  but showing the vacuum tool in its inverted position relative to the bonding part; 
         FIG. 4  is a view of the bonding part in contact with the formed adhesive elements held by the vacuum tool and having an insert which is a close-up of the interface of the adhesive side of the bonding part with the formed adhesive elements; 
         FIG. 5  is a view of the underside of the bonding part having a plurality of formed adhesive elements positioned thereon; 
         FIG. 6  is an elevational view of the bonding part and its formed adhesive elements relative to the substrate; 
         FIG. 7  is a view similar to that of  FIG. 6  but showing the bonding part adhered to the substrate; 
         FIG. 8  is a view similar to that of  FIG. 1  but showing an alternate embodiment of the reservoir such that a single layer of adhesive elements are provided; 
         FIG. 9  is a view similar to that of  FIG. 8  but showing the vacuum tool with a plurality of formed adhesive elements in place against the adhesive element holding face; 
         FIG. 10  illustrates the vacuum tool in position above the matrix according to an alternate embodiment of the method of attachment of the formed adhesive elements to a bonding part; 
         FIG. 11  illustrates the formed adhesive elements, now transferred from a reservoir, in position in the apertures formed in the upper surface of the matrix; 
         FIG. 12  illustrates the substrate positioned above the formed adhesive elements; 
         FIG. 13  illustrates the ejector pins of the matrix as having pushed the formed adhesive elements into contact with the bonding part; and 
         FIG. 14  illustrates an alternate embodiment of the matrix assembly according to the disclosed invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following figures, the same reference numerals will be used to refer to the same components. In the following description, various operating parameters and components are described for different constructed embodiments. These specific parameters and components are included as examples and are not meant to be limiting. 
     The formed adhesive elements referenced in the present application and their attachment to a bonding part are generally discussed in U.S. Pat. No. 9,133,377, which issued to Bremont et al. for an invention titled Adhesive Polyurethane Powder Capable of Being Activated by Heat, and which is assigned to the same assignee as the present invention. A method and apparatus for positioning, holding and moving the formed adhesive elements for attachment to a bonding part are disclosed in U.S. Pat. No. 9,284,134, which issued to Hansel et al. for an invention titled Method and Apparatus for Placing Adhesive Element on a Matrix, and which is assigned to the same assignee as the present invention. 
     The figures illustrate a vacuum tool, generally illustrated as  10 , used to transfer formed adhesive elements  12  from a reservoir either directly to a heated bonding part  14  or indirectly by first transferring the formed adhesive elements to a matrix assembly, generally illustrated as  16 . The bonding part  14  includes an adhesive coating surface  18 . 
     With reference to  FIGS. 1 through 4 , the vacuum tool  10  is illustrated. The vacuum tool  10  includes a vacuum tool body  20  having a vacuum tool body plenum  22  centrally formed therein. The vacuum tool  10  includes an adhesive element holding face  24 . Formed through the adhesive element holding face  24  is a plurality of vacuum lines  26  in fluid communication with the vacuum tool body plenum  22 . An outlet line  28  is also formed in fluid communication with the vacuum tool body plenum  22 . The outlet line  28  is attached to a vacuum-forming pump (not shown). 
     A reservoir  30  is provided that is substantially filled with the formed adhesive elements  12 . It should be understood that while the formed adhesive elements  12  are illustrated as having spherical shapes formed adhesive elements having other shapes, such as disc or oblong (neither shown), may be used with the disclosed invention. The first embodiment reservoir  30  includes a base  32  within which a first embodiment reservoir plenum  34  is formed. A series of air lines  36  is provided between the first embodiment reservoir plenum  34  and the interior of the first embodiment reservoir  30  into which pressurized air is introduced. The pressurized air passes into the first embodiment reservoir plenum  34  and out of the first embodiment reservoir plenum  34  out of the air lines  36  to help lift the formed adhesive elements  12  as may be needed for contact with the vacuum tool  10 . 
     The arrangement shown in  FIG. 1  illustrates the tool in its idle position. 
     In operation, and as shown in  FIG. 2 , a vacuum is created within the vacuum tool  10  and the vacuum tool  10  is lowered into the first embodiment reservoir  30  until contact with the formed adhesive elements  12  is made, assisted as needed by the above-described air flow system provided in the base  32  of the first embodiment reservoir  30 . At this time certain ones of the formed adhesive elements  12  are drawn to the outer open ends of the vacuum lines  26  and are held in place by suction. 
     With certain ones of the formed adhesive elements  12  adhered to the adhesive element holding face  24  of the vacuum tool  10 , the vacuum tool  10  is then moved to a position in which the formed adhesive elements  12  are facing the adhesive coating surface  18  of the bonding part  14  as shown in  FIG. 3 . This position can be an inverted position or can be any of a number of positions. The bonding part  14  may be held by a holding tool (not shown) during this part of the operation. 
     At some point prior to contact with the formed adhesive elements  12  the bonding part  14  is heated to a temperature sufficient to partially melt the contact area of the formed adhesive element  12  being attached. The heated bonding part  14  and the formed adhesive elements  12  are then put into contact with the formed adhesive elements  12  as illustrated in  FIG. 4 . An inset is provided in conjunction with  FIG. 4  in which the slight melt of the formed adhesive element  12  is shown for attachment to the bonding part  14 . The formed adhesive elements  12  are released by switching off the vacuum. Pressure can be used to eject the formed adhesive elements. 
       FIG. 5  generally shows the adhesive-contacting surface  18  of the bonding part  14  with the array of formed adhesive elements  12  attached thereto after processing according to the operations set forth in  FIGS. 1 through 4  and discussed in conjunction therewith. The array of formed adhesive elements  12  shown in  FIG. 5  are for illustrative purposes only and is not intended as being limiting as other arrays may be used. 
     Once the formed adhesive elements  12  are attached to the bonding part  14 , the bonding part  14  is lowered into position relative to a substrate  40  so that the bonding part  14  bonds with the substrate  40 . The pre-loading appearance of the bonding part  14  and the substrate  40  is illustrated in  FIG. 6 . 
     Once the bonding part  14  is properly adhered to the substrate  40  as shown in  FIG. 7 , the bonding part holding tool (not shown) releases the bonding part  14  and is withdrawn away from the bonding part  14 . 
     The first embodiment reservoir  30  shown in  FIGS. 1 and 2  is one possible choice for use during the transfer operation of the disclosed invention. An alternative embodiment of the reservoir for holding the formed adhesive elements  12  is shown in  FIGS. 8 and 9 . With reference to these figures, a second embodiment reservoir  50  is shown having a face  52  is illustrated. The face  52  has a formed adhesive element holding recessed area  54  formed therein. A single layer of formed adhesive elements  12  is formed in the formed adhesive element holding recessed area  54 . 
     In  FIG. 8  the vacuum tool  10  is shown generally positioned above the formed adhesive elements  12  in the second embodiment reservoir  50 . Air is drawn out of the vacuum tool  10  and it is lowered into position as shown in  FIG. 9  such that certain ones of the formed adhesive elements  12  come into contact with the outer open ends of the vacuum lines  26  and are held in place by suction. The vacuum tool  10  and its complement of formed adhesive elements  12  is then positioned relative to a heated bonding part (not shown) for adhesion as set forth above with respect to  FIGS. 3 and 4 . 
       FIGS. 1 through 9  generally relate to the structure and use of the vacuum tool  10  for transferring formed adhesive elements  12  from a first embodiment reservoir  30  (or a second embodiment reservoir  50 ) directly to the heated bonding part  14 . However, it may be preferred to transfer the formed adhesive elements  12  first to the matrix assembly  16  and then to the heated bonding part  14 . This method of attachment and its associated apparatus is illustrated in  FIGS. 10 through 13 . 
     With reference to  FIGS. 10 through 13 , the vacuum tool  10  and the matrix  16  are illustrated. The matrix  16  includes a matrix body  60  having an upper surface  62 . Formed within the upper surface  62  is a plurality of formed adhesive holding apertures  64 . The lower end of each of the formed adhesive holding apertures  64  is continuous with an ejector pin channel  66 . The inner diameter of the formed adhesive holding aperture  64  is greater than the inner diameter of the adjacent ejector pin channel  66  whereby a shoulder  68  is formed at the base of the formed adhesive holding aperture  64 . The shoulder  68  prevents the formed adhesive element  12  from entering the ejector pin channel  66 . The ejector pins can be guided in the matrix plate or in a plate underneath the matrix plate. 
     An ejector pin assembly  70  includes a plurality of ejector pins  72  attached to an ejector pin base  74 . A portion of each of the plurality of ejector pins  72  is reciprocatingly fitted within its respective ejector pin channel  66 . The ejector pin assembly  70  is operated by a drive unit (not shown) such that the ejector pins  72  move within the matrix body  60  simultaneously. 
     With particular reference to  FIG. 10 , the complement of formed adhesive elements  12  adhere to the adhesive element holding face  24  as the vacuum within the vacuum tool  10  still remains. The vacuum tool  10  is positioned above the matrix  16  as shown. Once the vacuum with the vacuum tool  10  is switched off, the formed adhesive elements  12  drop within their respective formed adhesive holding apertures  62  as illustrated in  FIG. 11 . Pressure can be used to eject the formed adhesive elements  12 . In this  FIG. 11 , the vacuum tool  10  has been moved away. 
     With the formed adhesive elements  12  in place, the heated bonding part  14  is positioned over the matrix body  60  as shown in  FIG. 12 . Once in position, the ejector pin assembly  70  is manipulated such that the ejector pins  72  are moved into the matrix body  60  and press against the undersides of the formed adhesive elements  12 , thus pushing the formed adhesive elements  12  against the adhesive coating surface  18  of the heated bonding part  14  as shown in  FIG. 13 . The heated bonding part  14  can then be moved away from the matrix assembly  16  and applied to the substrate  40  as shown and discussed above in relation to  FIGS. 6 and 7 . 
     A vacuum arrangement may be provided to assist the formed adhesive elements  12  in being guided into and held in the formed adhesive element holding apertures  64 . This arrangement is shown in  FIG. 14  in which a matrix assembly  16 ′ is shown. The matrix assembly  16 ′ includes a vacuum assembly  76  having a vacuum chamber  78  formed therein. The vacuum chamber  78  is fluidly attached to an air exhaust line  80  which is itself fluidly attached to a vacuum pump (not shown). According to this arrangement, the vacuum helps to guide the adhesive elements  12  to the holding apertures  64 . Once the formed adhesive elements  12  are positioned in the formed adhesive element holding apertures  64  the vacuum created by the vacuum chamber  78 , the air exhaust line  80  and the associated vacuum pump assists in holding the formed adhesive elements  12  in place against the upper ends of the ejector pins  72 . 
     The disclosed method and apparatus provides a robust, easy and cost effective method of transferring formed adhesive elements either directly to a bonding part or to the bonding part via a matrix. 
     The foregoing discussion discloses and describes exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, that modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.