Abstract:
A blister packaging machine for packaging product includes a frame, a heater that is supported by the frame and movable with respect to the frame, a hydraulic clamp connected to the heater, an insulator is provided to adequately thermally insulate the hydraulic clamp from the heater, and a heat sealing member for contacting a heat sealable item during use. The heat sealing member is adapted to be connected to the heater by way of the hydraulic clamp. The heater and the heat sealing member are adapted to move so that the heat sealing member contacts the heat sealable item.

Description:
FIELD OF THE INVENTION 
     This invention pertains to a heat sealing apparatus, and particularly, a heat sealing apparatus for heat sealing blister packages. 
     BACKGROUND OF THE INVENTION 
     In the discussion of the state of the art that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art against the present invention. 
     Blister packages are used to package a variety of different products. Blister packages typically comprise two pieces which are referred to as a blister on one side (e.g., a plastic carton often having a formed cavity to receive a product) and a card on the other side (e.g., a panel of plastic, cardboard, or other suitable material and which is often planar). Depending on the item to be sealed and the desired function of the package, e.g., multiple items separately contained in one blister seal or a single item in a single blister seal, or multiple differently shaped containers in a single blister seal, the blister packages are differently shaped. 
     During sealing of a blister package, the contents to be sealed are placed between the two pieces, and heat is applied to the blister package in a particular pattern, thereby sealing the blister to the card, thus sealing the contents inside the blister package. It is often necessary to apply a temperature of at least 300 degrees Fahrenheit to the blister packages to achieve a proper seal, and temperatures are sometimes required up to around 550 degrees Fahrenheit. This can be accomplished with an electrical resistance heater that is shaped so that it contacts and transfers heat to the blister packages in a particular pattern. However, for every different shaped blister package, the heater must be differently shaped to apply the proper pattern of heat to the blister package. 
     One option would be to maintain a number of differently shaped heaters to seal the different shaped blisters and to change the heater depending on the blister to be sealed. However, heaters are relatively costly and relatively burdensome to replace, therefore, changing a heater to correspond to different shaped blisters presents a number of issues. 
     Another solution is to use differently shaped heat sealing members that removably connect to the heater. The different heat sealing members each posses the particular shape required to transmit the heat from the heater to the blister package in the particular pattern necessary to seal the blister. When a different shaped blister package needs to be sealed, the heat sealing member is disconnected from the heater and a differently shaped heat sealing member is connected in its place. 
     A presently known system for changing heat sealing members includes manually operated clamping mechanisms that are normally of the “sheet metal” variety. A conventional clamping configuration is shown in  FIGS. 4A and 4B , where a heating member  220  has a sheet metal member  600  positioned against the heater. The heater  220  has a receiving opening  320  and the sheet metal member  600  has an opening  610  adjacent to the receiving opening  320 . The opening  610  has a narrow portion  615  and a wider circular portion  620 . A heat sealing member  4  has a heat sealing plate  335  and a pole  700 . The pole  700  extends from the heat sealing member  4  and has a narrow portion  720  between two wide portions  710 ,  730 . During clamping, the user manually positions the heat sealing member  4  against the heater  220  so that the pole  700  extends through the receiving opening  320  and the wide portion  620  of the opening. To close the clamp, the sheet metal piece  600  is slid in the direction X, and the narrow portion  615  of the opening  610  is positioned around the narrow portion of the pole  720 , thereby securing the heat sealing member against the heater  220 . 
     One challenge associated with removably attached heat sealing members involves the clamping of the heat sealing member  4  to the heater  220 . During clamping, the user lifts the heat sealing member  4  (which typically weighs about at least 20 lbs.) to a position below the heater  220 . The user then lifts the heat sealing member  4  toward the heater  220  so that the poles  700  extend through the openings  320  in the heater  220  and through the openings  610  in the sheet metal clamping apparatus located adjacent to the heater  220 . The user then manually slides the sheet metal clamp  600  in the direction X, positioning the narrow portion  720  of the pole  700  in the narrow portion of the opening  610 , thereby securing the pole  700  and the heat sealing plate  335  against the heater  220 . This operation is generally relatively challenging for the user. 
     Another issue associated with the conventional method of using heat sealing members involves unclamping and removing the heat sealing member after use. After use, the heat sealing member  4  is very hot for a significant period of time. Should the user not be able to wait for the heat sealing member  4  to adequately cool, the user is often presented with the task of unclamping the heat sealing member  4  while it is still extremely hot. To do this, the user normally wears thermally insulated protective gloves, and holds the heat sealing member  4  with one arm while releasing the clamps with the other arm. The user than removes the heat sealing member  4  from the heat sealing apparatus. 
     A further challenge associated with the conventional clamping mechanisms of the “sheet metal” variety is their tendency to deform over time, thereby allowing for a gap to be present between the heat sealing member  4  and the heater  220  which can create inefficient heat transfer between the heater  220  and the heat sealing member  4 . 
     SUMMARY 
     One embodiment is generally directed to a blister packaging machine for packaging product, comprising, a frame, a heater that is supported by the frame and moveable with respect to the frame, a hydraulic clamp connected to the heater, an insulator provided to adequately thermally insulate the hydraulic clamp from the heater, a heat sealing member for contacting a heat sealable item during use, the heat sealing member being adapted to be connected to the heater by way of the hydraulic clamp, and whereby the heater and the heat sealing member are adapted to move so that the heat sealing member contacts the heat sealable item. 
     Another embodiment is generally directed to a heat sealing apparatus, comprising, a frame, a heater that is moveable with respect to the frame and is adapted to move toward a heat sealable item, thereby transmitting heat to the heat sealable item to seal the item, and a hydraulic clamp connected to the heater, the hydraulic clamp being adequately thermally insulated from the heater. 
     Another embodiment is generally directed to a method of attaching heat seal members to a heater in a heat seal apparatus for heat sealing a heat sealable package, the heat sealing apparatus comprising a frame, a heater that is supported by the frame and movable with respect to the frame, heat sealable items that are supported by the frame and are adapted to be positioned so that the heater can move toward and away from the support member, comprising, positioning a heat sealing member on the support member so that the heat sealing member is in a position whereby the heat sealing member may be connected to the heater by way of the hydraulic clamp, and actuating the hydraulic clamp thereby holding the heat sealing member against the heater. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of embodiments can be read in connection with the accompanying drawings in which like numerals designate like elements and in which: 
         FIG. 1  shows an embodiment of the present invention; 
         FIGS. 2A–2E  show front views of a portion of an embodiment of the present invention in different operating positions; 
         FIG. 3A  shows a magnified view of a portion of the apparatus shown in  FIG. 2B ; 
         FIG. 3B  shows a magnified view of a portion of the apparatus shown in  FIG. 2A ; 
         FIG. 4A  shows a side view of a conventional clamping apparatus; and 
         FIG. 4B  shows a top view of the clamping apparatus shown in  FIG. 4A . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     An embodiment of a heat sealing apparatus according to the present invention is shown in  FIG. 1 . The heat sealing apparatus  1  includes a frame  100  having side members  110 , top members  160 , bottom members  140 , and inner support members  120 ,  150 ,  170 ,  180 , and  190 . The frame is supported on a surface by feet  130 . 
     A heat sealing press apparatus  2  and a heat sealing support apparatus  3  are supported within the frame  100 . 
     The heat sealing press apparatus  2  includes a hydraulic cylinder  210  that is supported by the member  150 . The hydraulic cylinder  210  acts on a pressing member  260 , whose stability during movement is maintained by guide rods  240  that slidingly extend through the member  150 . A heater  220  is supported on the pressing member  260  via vertical support members  250 . The heater  220  has receiving openings  230  that extend through the heater  220 . Pneumatic clamping mechanisms  300  are connected to the heater  220  in a position aligned with the receiving openings  230 . An example of a pneumatic clamping mechanism  300  is the model 377 Shouldered Mini Cylinder Lock™ available from Edward D. Segen &amp; Co, Inc. of 3 Schooner Lane, Suite 1-11, Milford, Conn. 06460 (www.segen-online.com). 
     The pneumatic clamping mechanism  300  is hydraulic by definition, and any hydraulic clamping mechanism can be used in place of the pneumatic clamping mechanism  300  described herein. 
     The heat sealing support apparatus  3  includes a hydraulic cylinder  360  connected to a member  350  that is supported by the members  170 ,  180 ,  190 . A piston of the hydraulic cylinder  360  is connected to a movable support member  340  that raises and lowers with the piston. A heat sealing member  4  is supported prior to clamping, on a tray  370  on the member  340 . As shown, the tray can have handles  375  thereby allowing the user to carry the tray  370  with little risk of contacting the heat sealing member  4  with their body. The heat sealing member  4  includes shaped protrusions  330  that are connected to a heat sealing plate  335 . The shaped protrusions  330  conform to the particular blister to be sealed. One or more poles  305  extend from the sealing plate  335  upward toward the heater  220 , and include a first length  320  and a second length  310  that is clamped by the pneumatic clamps  300 . 
     A number of positions of the apparatus that can be realized during clamping of the heat sealing member  4  are sequentially shown in  FIGS. 2A–2E . 
       FIG. 2A  shows the heat sealing press apparatus  2  when the hydraulic cylinder  210  is in a retracted position, and the heat sealing support apparatus  3  when the hydraulic cylinder  360  is retracted. The heat sealing member  4  is carried by a tray  370 . The tray  370  and the heat sealing member  4  are supported by the support member  340 . The tray  370  holding the heat sealing member  4  can be carried by the user and placed in the position shown in  FIG. 2A . 
     In  FIG. 2B , the hydraulic cylinder  210  is extended, and the heater  220  is lowered with respect to the position shown in  FIG. 2A . In this position, the second lengths  310  of the poles  305  are inside the receiving openings  230  of the heater  220 . 
     In  FIG. 2C , the hydraulic cylinder  210  is in an extended position, and the hydraulic cylinder  360  is also in an extended position, thereby raising the support member  340  and the heat sealing member  4 . The second lengths  310  of the poles  305  are inside the pneumatic clamps  300 . Normally, when in this position, the pneumatic clamps  300  are actuated, thereby clamping the second lengths  310  of the poles  305  and holding the heat sealing plate  335  against the heater  220 . 
     In  FIG. 2D , the pneumatic clamps  300  are actuated and clamp the second lengths  310  of the poles  305 . The hydraulic cylinder  360  is retracted, thereby lowering the support member  340  and the tray  370 . The heat sealing plate  335  remains against the heater  220  as shown in  FIG. 2C . 
     In  FIG. 2E , the hydraulic cylinders  210  and  360  are both in a retracted position. The second lengths  310  of the poles  305  are clamped by the pneumatic clamps  300 , thereby holding the heat sealing plate  335  against the heater  220 , and the support member  340  and the tray  370  are lowered away from the heat sealing member  4 . The tray  370  can be removed from this position by the user prior to heat sealing of packages. 
     The heat sealing member  4  can be unclamped in a manner opposite to that described above for clamping of the heat sealing member  4 . To unclamp the heat sealing member  4 , as shown in  FIG. 2E , the user can place the tray  370  on the support member. As seen in  FIGS. 2C and 2E , the hydraulic cylinders  210  and  360  can be extended so that the heat sealing member  4  is supported by the support member  340  and the tray  370  and the pneumatic clamps  300  can be released. As seen in  FIGS. 2A and 2B , the hydraulic cylinders  210  and  360  can then be retracted and the user can remove the heat sealing member  4  by carrying the tray  370 . 
     The heater generally operates at temperatures in the range of 300 degrees Fahrenheit to approximately 550 degrees Fahrenheit. Pneumatic clamps  300  include elastic seals that are involved in effecting a clamping force on the second length of the poles  320 . These seals are typically rated for operation up to around a maximum of 400 degrees Fahrenheit, and under normal operating conditions of the described heat sealing apparatus would tend to melt or be otherwise negatively affected. Therefore, there is an issue pertaining to maintaining the pneumatic clamps at a temperature that is adequately lower than that realized by the heater  220  or the heat sealing member  4 . This maintenance could be accomplished by insulating the pneumatic clamp  300  from the heater  220 . 
       FIG. 3A  shows an insulating member  400  that includes a rigid plate  410 , in this case aluminum, and a layer of thermal insulation  420 . The thermal insulation  420  should operate at temperatures at least as high as around 500 degrees Fahrenheit and have a heat flow rating of somewhere in the range of 0.25–0.75 (Btu·in.)/(hr·sq. ft.) at 500 degrees Fahrenheit. Preferably, the insulation can be a ceramic fiber blanket that is capable of continuously operating at temperatures as high as approximately 2300 degrees Fahrenheit. An example of thermal insulation is a Ceramic Fiber Strip, Part No. 87575K83 available from McMaster-Carr, Inc. (www.mcmaster.com). Other methods of thermally insulating the pneumatic clamp  300  can also be employed. 
     In another embodiment shown in  FIG. 3B , each pole  305  includes insulation layer  420 , in this case a ceramic fiber layer, located between the second length  310  and the first length  320 . Also, an insulation layer  420  can be located between the second length  320  and the heat sealing plate  335 . This configuration prevents too much heat from transferring from the heater  220  through the first length  320  to the second length  310  to the pneumatic clamp  300 . 
     Any combination of configurations of the insulation can be employed that adequately insulate the pneumatic clamp  300 . For example, insulation can be placed between the pneumatic clamp  300  and the heater  220 , between the heater  220  and the rigid member  410 , between the first length  320  and the heat sealing plate  335 , between the first length  320  and the second length  310 , or any combination thereof. 
     Although the present invention has been described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without department from the spirit and scope of the invention as defined in the appended claims.