Patent Document

BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to a method and apparatus for sealing cover tape to carrier tape and, more particularly, to a sealing mechanism that applies heat and/or pressure to seal the cover tape to the carrier tape.  
         SUMMARY OF THE INVENTION  
         [0002]    The invention provides a sealing mechanism that is connected to an actuator that moves the mechanism toward an adhesively backed cover tape and a carrier tape. If the adhesive is heat sensitive, the sealing mechanism applies heat to the cover tape to transform the adhesive into a molten state. The sealing mechanism applies pressure through sealing wheels to press the cover tape against the carrier tape, thereby bonding the heat sensitive or pressure sensitive adhesive between the carrier tape and cover tape. A biasing member biases the mechanism away from the cover and carrier tapes. The actuator is actuable to overcome the biasing force of the biasing member and to initiate contact between the sealing mechanism and the cover tape. When the actuator is disengaged, the biasing member moves the sealing mechanism away from the cover tape. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0003]    [0003]FIG. 1 is an exploded perspective view of a sealing mechanism embodying the invention.  
         [0004]    [0004]FIG. 2 is a section view of the sealing mechanism of FIG. 1.  
         [0005]    [0005]FIG. 3 is a section view taken along line  3 - 3  in FIG. 2.  
         [0006]    [0006]FIG. 4 is a section view of an alternative construction of the sealing mechanism.  
         [0007]    [0007]FIG. 5 is a section view taken along line  5 - 5  in FIG. 4.  
         [0008]    [0008]FIG. 6 is a section view of the sealing mechanism of FIG. 1 and an alternative construction of an actuator assembly.  
         [0009]    [0009]FIG. 7 is a section view taken along line  7 - 7  in FIG. 6. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0010]    [0010]FIG. 1 illustrates a sealing mechanism  10  that includes a truck  14  and a shoe  18 . The truck  14  includes front and rear depending tabs  22 ,  26  to which front and rear wheels  30 ,  34  are rotatably mounted. The wheels  30 ,  34  are generally spool-shaped and include side edges or flanges  38 . The truck  14  also includes a cavity or bore  42  into which a heating element  46  may be inserted. The shoe  18  includes a central cavity  50  and front and rear rails  54 ,  58  along its bottom edge.  
         [0011]    With reference to FIGS.  1 - 3 , the truck  14  is inserted into the central cavity  50 , and the front wheel  30  of the truck  14  extends through an opening in the middle of the shoe  18  between the front and rear rails  54 ,  58 . The rear wheel  34  of the truck  14  trails behind the rear rails  58  of the shoe  18  when the truck  14  and shoe  18  are assembled. When assembled, the flanges  38  of the truck&#39;s wheels  30 ,  34  are generally aligned or coplanar with the rails  54 ,  58  of the shoe  18 , although the rails  54  are slightly wider than the flanges  38  of the truck&#39;s wheels  30 ,  34 .  
         [0012]    As seen in FIGS. 1 and 3, the truck  14  and shoe  18  each include a pair of holes  62 ,  66 , respectively. Pins  70  extend through the matching sets of holes  62 ,  66  to couple the truck  14  and shoe  18  together. The holes  62  in the truck  14  snugly receive the pins  70 , while the holes  66  in the shoe  18  are oversized or of larger diameter than the pins  70  so that there is play between the shoe  18  and the pins  70 . This play permits the shoe  18  to float up and down with respect to the truck  14 .  
         [0013]    Turning to FIGS. 2 and 3, an actuator bracket  74  is mounted to the truck  14 . The actuator bracket  74  is generally T-shaped in cross-section as seen in FIG. 3, and includes a base  78  and a cross-bar  82 . Threaded fasteners  86  extend through holes in the base  78  of the actuator bracket  74  and are threaded into threaded holes  90  (see FIG. 1) in the top of the truck  14 .  
         [0014]    The cross-bar  82  of the actuator bracket  74  is received within a generally C-shaped sliding mechanism  94 , and a biasing member, such as the illustrated compression spring  98 , supports the sliding mechanism  94 . In its undeflected condition, the compression spring  98  lifts the actuator bracket  74 , truck  14 , and shoe  18  upwardly, as will be discussed in more detail below. The sliding mechanism  94  is interconnected with a support structure  102 , for example in a vertical track  104  or the like, to permit the sliding mechanism  94  to slide vertically, but to prevent the sliding mechanism  94  from moving left or right in FIG. 3.  
         [0015]    A pivot pin  106  pivotally interconnects the cross-bar  82  to the sliding mechanism  94 , and the actuator bracket  74  is free to pivot about the pivot pin  106  as permitted by the clearance between the ends of the cross-bar  82  and the inside of the C-shaped sliding mechanism  94 . However, the cross-bar  82  of the actuator bracket  74  is captured within the C-shaped sliding mechanism  94  such that the actuator bracket  74  may not move left or right as seen in FIG. 3.  
         [0016]    The support structure  102  extends over the sliding mechanism  94  and the sealing mechanism  10 , and supports an actuator  110 . The actuator  110  may include, for example, a pneumatic cylinder. The actuator  110  includes a linearly extendable and retractable arm or piston  114  having a ball-and-socket type end  118 . The ball-and-socket end  118  abuts the top of the base  78  of the actuator bracket  74 . The actuator  110  is selectively actuable to push down on the actuator bracket  74  and deflect the biasing member  98  to its deflected condition. The ball-and-socket end  118  permits the actuator  110  to apply such downward force to the actuator bracket  74 , even as the actuator bracket  74  pivots on the pivot pin  106  (as indicated with arrow  122  in FIG. 2).  
         [0017]    With reference to FIGS. 2 and 3, the sealing mechanism  10  is used to seal a cover tape  126  to a carrier tape  130 . The carrier tape  130  includes side flanges  134  and serially spaced compartments  138  that extend along a longitudinal axis  140  and are positioned between the flanges  134 . The compartments  138  are adapted to contain parts  142 , which may be, for example, microprocessors, computer chips, circuit boards, or any other electrical or mechanical components. The cover tape  126  is laid over the carrier tape  130  and includes lines or strips of adhesive running along the longitudinal extent of the cover tape  126  and extending along the flanges  134  of the carrier tape  130 . The adhesive may be pressure-sensitive adhesive, which requires only pressure to activate it, or heat-sensitive adhesive, which requires heat and pressure to activate it. The rails  54 ,  58  of the shoe  18  and the flanges  38  of the truck wheels  30 ,  34  are aligned or coplanar with the lines of adhesive. The carrier tape  130  is supported at its flanges  134  by guide rails  146  under the sealing mechanism  10 .  
         [0018]    In operation, if the adhesive is the heat sensitive type, the heating element  46  is energized to generate heat and warm up the truck  14  and shoe  18 . Both the truck  14  and the shoe  18  are preferably constructed of thermally conductive material and become hot enough to activate the adhesive. In its at-rest condition (i.e., when the actuator  110  is retracted), the spring  98  lifts the truck  14  and shoe  18  up off the carrier tape  130  and cover tape  126 . The tape  126 ,  130  is pulled under the sealing mechanism  10  at a selected rate by a motor or other prime mover.  
         [0019]    Once the tape  126 ,  130  is in motion, the actuator  110  extends the actuator arm  114 , which applies a downward force to the actuator bracket  74  through the ball-and-socket end  118 . This causes the actuator bracket  74 , sliding mechanism  94 , and sealing mechanism  10  to slide downwardly, which deflects or compresses the spring  98 . In response to such downward movement of the sealing mechanism  10 , the flanges  38  of the truck wheels  30 ,  34  sandwich the cover tape  126  and carrier tape flanges  134  against the guide rails  146 .  
         [0020]    Also, the front and rear rails  54 ,  58  come into contact with the cover tape  126 , therefore, bringing the shoe  18  to rest on the cover tape  126 . As mentioned above, the shoe  18  is free floating with respect to the truck  14  due to the pins  70  and oversize holes  66  in the shoe  18 . Therefore the shoe  18  is free to ride up and down over any bumps in the cover tape  126  and carrier tape  130 , even as the actuator  110  applies a substantially constant downward force on the truck  14 . Additionally, the ball-and-socket end  118  of the actuator arm  114  and the pivot pin  106  connection permit the actuator  110  to apply a substantially constant downward force on the truck  14 , even as the truck  14  pivots as it encounters bumps in the cover tape  126  and carrier tape  130 . The ball-and-socket end  118  and pivot pin  106  therefore permit the cover tape  126  to be in substantially uninterrupted and continuous contact with the rails  54 ,  58  and wheels  30 ,  34 .  
         [0021]    The tape  126 ,  130  moves in a downstream direction  150  (FIG. 2). As the tape  126 ,  130  passes under the sealing mechanism  10 , the lines of adhesive are warmed by the front rails  54  of the heating shoe  18 . The front truck wheels  30  are also heated by conduction and convection and apply additional heat to the lines of adhesive, which activates the lines of adhesive. Then the tape  126 ,  130  is pulled under the front wheel  30 , and the front wheel flanges  38  apply pressure to the adhesive and sandwich the cover tape  126  and carrier tape flanges  134  together against the guide rails  146 . Once the molten adhesive cools and cures, the bond is complete.  
         [0022]    The rear rails  58  of the shoe  18  and the rear wheel  34  of the truck  14  are provided as back up in the event the bond is not completed by the front wheel  30 . The rear rails  58  of the shoe  18  apply heat which activates the adhesive, and the rear wheel  34  applies pressure to the adhesive to complete the bond. Additionally, if the taper machine through which the tape  126 ,  130  is moving is powered down during a run, the actuator arm  114  is retracted, which permits the spring  98  to lift the truck  14  and shoe  18  off the tape  126 ,  130 . This prevents prolonged exposure of high heat to the tape  126 ,  130 , and reduces the likelihood that the cover tape  126  will melt, warp, or otherwise be damaged by such prolonged exposure. In the event of such a shut-down, there may be incomplete bonding in the length of tape  126 ,  130  under the sealing mechanism  10 . When the machine is again powered up and the sealing mechanism  10  is pressed down against the tape  126 ,  130 , the rear rails  58  of the shoe  18  and the rear wheel  34  complete any such incomplete bonds.  
         [0023]    If the adhesive is activated by pressure only, then the heating element  46  need not be activated. The illustrated sealing mechanism  10  may therefore be used for sealing both heat sensitive adhesive and pressure sensitive adhesive, and the sealing shoe  18  would not have to be switched out for a different sealing shoe when the adhesive is changed.  
         [0024]    It should be noted that the sealing mechanism  10  may be adapted for use on all standard tapes  126 ,  130 . There are several different widths of cover and carrier tapes  126 ,  130  in industry (e.g. 8 mm, 12 mm, and 16 mm) and the truck  14  and shoe  18  may be configured with wheels  30 ,  34  and rails  54 ,  58  of varying widths and spacings to ensure proper sealing.  
         [0025]    [0025]FIGS. 4 and 5 illustrated an alternative construction of the sealing assembly. Where elements are similar to those described above, the same reference numerals are used. In this construction, the truck and shoe are integrally formed with each other as a single part  150 . To facilitate bumps in the cover and carrier tapes  126 ,  130  in this construction, the support rails  54 ,  58  are positioned a fixed distance D from the cover tape  126 . The distance D should be a minimum of 0.0005 inches to ensure proper functionality of the integral truck/shoe  150 .  
         [0026]    [0026]FIGS. 6 and 7 illustrate an alternative actuator assembly  154  for use with the sealing mechanism  10  illustrated in FIGS.  1 - 3 . It will be appreciated that, although not illustrated, the sealing mechanism  10  illustrated in FIGS. 4 and 5 may also be used with the actuator assembly  154  illustrated in FIGS. 6 and 7. This actuator assembly  154  utilizes a servo or stepper motor  158  operable in a forward and a reverse direction. The motor  158  is mounted to a modified version of the support structure  102  which includes a depending portion  162 . Operably interconnected with the motor  158  is an eccentric or cam member  166 . A wheel or roller  170  is rotatably mounted within the base portion  78  of the actuator bracket  74 , and is in abutting relationship with the cam member  166 .  
         [0027]    The downward pressure applied to the carrier tape  130  and cover tape  126  through the wheels  30 ,  34  is a function of the direction and degree to which the motor  158  rotates the cam  166 . The magnitude of downward pressure may therefore be closely controlled by a central processing unit in communication with the motor  158 . As with the above-described embodiments, the actuator  158  may selectively remove the downward force, at which time the spring  98  lifts the truck/shoe member  150  off the tape  126 ,  130 .  
         [0028]    Although previously described constructions of the invention are described as including first and second sealing wheels  30 ,  34 , a single sealing wheel or more than two sealing wheels can be utilized and still achieve the desired sealing effect and still be within the spirit and scope of the invention. The sealing wheels  30 ,  34  can alternatively be powered rather than passive. Powered sealing wheels would reduce the amount of tension required on the cover and carrier tapes  126 ,  130  during the sealing process, and therefore reduce the chance of the cover and carrier tapes tearing or breaking.  
         [0029]    Sliding shoes, skids, or blades can be utilized in place of the sealing wheels  30 ,  34  described in the illustrated constructions. The sliding shoes would be mounted to the truck  14  in generally the same positions as the illustrated sealing wheels  30 ,  34 , but they would not rotate. The sliding shoes would slide over the top of the cover tape  126  to seal the cover and carrier tapes  126 ,  130  together.  
         [0030]    Alternatives to the heating element  46  can also be used and still be within the spirit and scope of the invention. For example heat pipes or heated wires can be utilized to direct heat to a predetermined area around the sealing wheels  30 ,  34 . These heat pipes or wires will provide enough heat to the cover tape  126  to cause the adhesive thereon to become molten and the sealing wheel provides sufficient pressure to the cover and carrier tape  126 ,  130  to achieve the same heat-sealing results as the previous constructions.  
         [0031]    Although a single sealing mechanism  10  is illustrated and described above, it should be appreciated that multiple sealing mechanisms  10  may be used in series if necessary. Also, multiple rows of cover and carrier tapes  126 ,  130  can run side by side with one another and, therefore, multiple sealing mechanisms  10  may be positioned side by side to seal the side by side rows of cover and carrier tapes  126 ,  130 . Each of the side by side sealing mechanisms  10  may be connected to individual actuators  110  or all of the side by side sealing mechanisms  10  may be connected to a single actuator  110 .  
         [0032]    Although the illustrated embodiment shows the sealing mechanism  10  above the cover and carrier tapes  126 ,  130 , it should be appreciated that the sealing mechanism  10  can be positioned below the cover and carrier tapes  126 ,  130  to seal the cover and carrier tapes  126 ,  130  from below. In such an embodiment, the front and rear rails  54 ,  58 , and flanges  38  of the sealing wheels  30 ,  34  would contact or be positioned a distance below the carrier tape  130 .  
         [0033]    The embodiments described above and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims.

Technology Category: b