Abstract:
An improved vertical, vial, impulse heat sealing apparatus, the improvements including a light weight, precision milled frame with increased interchangability of component parts and increased structural strength, a more positive toggle system that eliminates misalignments and allows more stringent tolerances, a safety lock system to prevent operating personnel injury, improved stability and leverage efficiency, improved heat distribution, modular precision components for improved maintenance capability, improved terminal connector materials and method for installing replacement heater bands, improved connector-wire routing, provisions for precision shim plate adjustment specially adapted for use with proprietary vials arranged in three tandem units of five vials each, special designed precision vial holders, and an alternate embodiment provides a conversion package for converting existing apparatus for automatic operation and improved safety.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to heat sealing apparatus and more particularly to an improved impulse heat sealing station for sealing polymeric medical vials in tandem after filling with a medicament. 
     2. General Background 
     Manually operated heat sealing apparatus such as the Virtrod™ have been in use for many years and have been adapted for use as medical vial sealing apparatus. However, such apparatus are considered archaic by today&#39;s standards. While spare parts and technical support are still available from some companies, such as TechnaSeal™, improved automated heat sealing machines have been developed to increase production demands. However, it is recognized that these older model vertical, special impulse heat sealing machines still play a vital role in today&#39;s medical labs where medications can be produced and packaged in relatively small quantities on site. As production requirements increase in such labs a heavy demand is placed on these older types of heat sealing machines. There comes a point where it is no longer economical to expand the capacity of the machines or maintain the equipment with spare parts, which continue to increase in cost, as originally designed. Expanding the number of vials per load or increasing vial material thickness exerts excessive strain on the toggles and reduces sealing quality due to inadequate heat distribution, resulting in higher maintenance cost and poor quality products. In most such machines like the Virtrod™ vertical vial sealer, sealing is achieved by simply bringing a movable heater head into contact with a stationary heater head. The polymeric material is thus pinched between the heads and heat is applied by an electrical heat strip running the length of the heads. The individual vials are held in racks of 4 or 8. The manually operated machines generally utilize a single over-center toggle lever to move the movable heater head into contact with the stationary head. The heat cycle is then timed to provide sufficient melting of the polymeric vial material and thus produce an effective seal However, as production requirements increase, the base units remains the same and longer heater heads are provided with higher wattage heater strips to accommodate longer racks of up to 14 vials. The single toggle operation then becomes over stressed and the toggle linkage becomes loose, causing misalignments of the heater bars, and allows for insufficient pressure on some of the vials, especially at the outer ends, thereby causing some vials to burn while others fail to make an effective seal. Such excessive heat causes the heater strips to have hot spots resulting in early failure. The longer heater bars are heavier, thereby requiring more torque to lift the movable bar, requiring operators to use both hands. Since no provision is made to shield the movable heater bar or provide a second handle, operators often receive severe burns. Further, since both hands are often used to operate the movable bars, it becomes more difficult to manipulate the movable head and hold the vial rack in position relative to the stationary heater head. No provision is made to hold the heavier movable heater heads in the up or open position while removing and replacing the vial racks, thereby resulting in more personnel injury due to burns. No provision is made to insure heater head alignment or to accommodate different thicknesses of vial polymeric materials. No provision is made to insure the proper pressure is placed on each vial to insure a quality seal. Polymeric vials are often produced in multi-cavity molds. When the vials are removed from such molds they are linked to each other by a relatively heavy web in groups or sets. It has been found that removing these webs takes time and excessive handling. In some cases, where sets of heat sealed packets are required, they are filled in the horizontal position or on a continuous feed system. In any case hand operated or manual sealing systems usually use only individual vials. Therefore, provisions need to be made to use the groups or sets, as produced by the vials manufacturing process, instead of handling the vials individually. This speeds up the filling and heat sealing process as well. However, it becomes necessary to provide precision racks and sealing head members with very efficient heat transfer capability to handle the groups in tandem. 
     No provision is made for non technical personnel to make repairs to this type of equipment. Simply replacing a heat strip is a major operation which often requires great dexterity due to the spring tensioning apparatus and procedure. 
     The prior art heater bars usually consist of a steel rectangular bar having a hole running lengthwise therethrough and tapped to receive water fittings. The bar is fitted at each end with a recessed terminal block composed of a micarta block with a stem portion extending from one side and tapped to receive a small screw on the opposite side. The terminal blocks are biased towards each end of the heater bar by a small spring imposed over the stem portion. The heater band is fitted with a pig tail wire at each end, soldered to the band at one end with a jack plug at the other. The band is then attached to the terminal connectors by compressing the two terminal blocks within the recesses in the heater block, thereby overcoming their bias and securing the heater band in place by the small screws mentioned above. This procedure requires more than two hands to accomplish and the heater bands often become loose relative to the micarta terminal blocks and burn the micarta resulting in premature failure. Teflon cloth strips are placed on either side of the heater bands and retained in place by elongated Teflon clamping strips, heat being dissipated throughout the heater bar as a function of its cross sectional area. Obviously, a better method is needed for replacing and protecting the heater bands and providing a more even distribution of heat. 
     Therefore, it behooves the industry to redesign the machines from time to time to improve their efficiency and thus improve their reliability, economics, and production capacity. 
     It is therefore an object of the this invention to provide a familiar but improved vertical, impulse heat sealing machine having a more substantial mechanical operating linkage for easier operation and more even distribution of pressure over the movable heater bars. 
     A further object is to provide a safer operation by providing insulated handles and locking bars. 
     Another object is to provide improved alignment between the moving and stationary heater bars and improve heat distribution along the bars. 
     Still another object is to reduce weight, improve replaceability, reduce maintenance and operating cost, improve handling efficiency, and maximize quality. 
     SUMMARY OF THE INVENTION 
     An improved vertical, vial, impulse heat sealing apparatus, the improvements including a light weight, precision milled frame with interchangability of component parts and increased structural strength, a more positive toggle system that eliminates misalignments allowing more stringent tolerances, a safety lock system to prevent operating personnel injury, improved stability and leverage efficiency, improved heat distribution, modular precision components for improved interchangability, improved terminal connector materials and method of heater band installation, improved connector-wire routing for improved heater bar replacement, provisions for precision shim plates specially adapted for use with proprietary vials in three tandem units of five vials each, specially designed precision vial holders, and an alternate embodiment providing a pneumatic conversion package for automatic operation and improved safety. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which, like parts are given like reference numerals, and wherein: 
     FIG. 1 is an isometric full assembly view of the improved heat sealing apparatus in the open position with vials and vial holder in position; 
     FIG. 2 is a top view of the assembly seen in FIG. 1; 
     FIG. 3 is an isometric full assembly view of the improved heat sealing apparatus in the closed position with vials and vial holder in position; 
     FIG. 4 is a vertical side view of the improved heat sealing apparatus in the closed position with vials and vial holder in position; 
     FIG. 5 is an exploded view of the stationary heater bar and its relation relative to the machine; 
     FIG. 5 a  is an enlarged side view of item  78  shown in FIG. 5; 
     FIG. 6 is a front elevation view of the connected vials; 
     FIG. 7 is an isometric view of the vial fixture; 
     FIG. 7 a  is an isometric view of item  134  partially show in in FIG. 7; and 
     FIG. 8 is an isometric view of pneumatic operated assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As first seen in FIG. 1, the improved vertical, impulse heat sealing assembly apparatus includes a base plate  12  machined from light weight aluminum, a vertical plate  14  flanked on each side and held in an attached position by gusset plates  16 , better seen in FIG. 2, attached at each side of the base plate  12 , a guide bar  18  attached to the upper or work surface of the base plate  12 , and an electrical control enclosure  20  fitted to the back or control side of the vertical plate  14 . The upper surface of the base plate  12  should be smooth and flat and the vertical plate  14  should be rigid, stable and perpendicular to the upper surface of the base plate  12 . The electrical controls are mounted to the control side of the vertical plate  14  and enclosed by panel  20  attached to the vertical plate  14  and the base plate  12 . The enclosure  20  is vented with louvers  22  to dissipate internal heat. Wiring from the heater bars  32 ,  44  are fed through holes  25  in the vertical mounting plate  14  for connecton to electrical controls located in the enclosure  20 . The electrical enclosure  20  contains all electrical components within, having only control switch  26  and buttons  28  and indicator lights  30  exposed as seen in FIG. 3. A stationary heater bar is attached to the mounting face of the vertical plate  14  opposite the control enclosure  20  and precision machined to be parallel with and at a precise height above the base plate  12 . 
     The movable arm assembly  33 , seen in FIG. 3, includes a pair of over-center toggle clamps  34  mounted on spacer blocks  36 , bolted to the vertical plate  14 . The lever portion  35  of each of the toggle clamps  34  is connected to each other by connecting a handle bar  38 , the handle bar  38  having a handle  40  located intermediate the toggle levers  35  and extending perpendicular thereto. The over-center clamp arms  42  of the toggle assembly  34  are rigidly connected to a movable heater bar  44  by blocks  46 , which are in turn connected to the heater bar  44 , as seen in FIG. 4, the assembly further including a lock bar  48  pivotally attached to one of the clamp arms  42  in a manner whereby an end of the lock bar  48  engages a notch in a stationary bracket portion  50  of the toggle assembly  34 , as illustrated in FIG. 1. A lifting bar  52  attached to the heel  54  of the heater bar  44  is also provided to assist in lifting the movable heater bar  44  and help prevent personal injury from burns. A micro limit switch  24  shown mounted to spacer block  26  in FIG. 3 is activated by adjustable arm assembly  56 , also attached to the movable heater bar  44 , as best seen in FIG.  2 . The assembly  56  includes a connecting bar  58 , a threadable adjusting element  60 , and a bumper element  62 . In operation the limit switch  24  is contacted by the adjusting element  60  and its bumper element  62  when the movable heater head  44  is brought into near proximity with the stationary heater bar  32 , thereby actuating the limit switch and the heater circuits for a timed cycle. 
     Turning now to FIG. 5, we see that the stationary bar assembly  32  is typically mounted to the vertical plate  14  by four screws  70  passing through the precision machined heater bar  72 . The one piece machined aluminum heater bar  72  is “L” shaped having vertical and horizontal leg portions which increases the bar&#39;s mass, thus increasing heat distribution. The horizontal portion, being the short leg portion of the “L”, is recessed at each end for receiving a terminal connector  78  and tapped along its length at intervals on both top and bottom sides for receiving screws  80  passing through the brass retaining plates  82 . The vertical portion of the bar  72  is through drilled lengthwise counter bored and tapped  74  at each end for water line fittings at each end and is grooved lengthwise along its upper edge to provide a wire channel  76 . The bar is further tapped along its upper edge for receiving screws  84  passing through as securing cover strip  86 . The notched recesses  88  are bored therein for receiving the pin and spring portion of the terminal connector assemblies  78  and are cross drilled and tapped to receive a set screw  90 . Unlike previous heat sealers of this type, which use micarta terminal connection blocks tapped to receive a terminal screw which often becomes loose and burns, the connector  78  as shown in FIG. 5 a  includes a ceramic block  92  having an integral pin portion or super imposed around and upon a pin  94 , the ceramic block is taped opposite the pin to receive a threaded stud  97 . A connecting nut  110  and washer  108  are provided cooperative with said stud  97 . When inserting the terminal connector  78  into the recess  88 , a spring  95  is superimposed over a portion of the stud  94  in a manner whereby the terminal connector is biased towards the end of the bar  74 . When installed, the spring is compressed and the set screws  90  set to retain the ceramic connector block  92  in place within the recess  88 . A high temperature insulating adhesive backed strip  100 , usually a Teflon coated fiberglass tape, is applied along the face  102  of the heater bar  72  conforming to all exposed surfaces and held firmly in place between the two brass plates  82 . The electrical heater band  104  is attached by placing the eyelet  106  over the exposed portions of each connector terminal stud  94  and securing thereto with the aforementioned washer  108  and nut  110 . The afore-mentioned set screws  90  are then loosened, thereby allowing the connector terminals to be extended due to biasing by the spring  95 , thereby placing the heater band  104  in tension. A non-adhesive backed insulating tape  112  is applied over the heater band  104 , thereby covering all of the exposed surfaces of the horizontal portion of the bar  72 . The high temperature insulating strip  112  being carefully applied over the electrical heater strip  104  and between the brass strips  82  and the horizontal portion of the bar  72  adjacent each side of the heater band face  102 . 
     A precision machined shim plate or bar  114  is attached to the stationary bar  72  adjacent the upper most brass plate  82  and secured to the bar  72  by screws  116 . A precision machined aluminum shim strip having slots  120  along one edge for adjustably mounting the shim strip  118  vertically to the shim bar  114  and a series of notches  122  located along the opposite edge which correspond to the spacing between vials  124  as shown in FIG. 6 connected by webs  126  molded in groups of five each. Therefore, the spacing between the vials  124  matches the spacing of the notches  122  of the shim plates  118  and the thickness of the shim plate  118  corresponds to the thickness of the vial&#39;s walls when properly sealed. In grouping the vials  124  in tandem or set of three groups of five vials each, a space equal to one web space is also provided between each group. The use of a shim plate  118  provides a method for controlling pressure uniformity and a neat appearance to the sealed vials. The vials  124  are held in precise location relative to the notches  122  in the shim plate  118  by a the vial filling and sealing fixture assembly  128  shown in FIG.  7 . The fixture is precision machined to match the vial groups as molded, shown in FIG. 7, and located in tandem of three sets. The fixture includes an upper horizontal plate machined to receive the upper tube portion  132  of the vials  124  and a second horizontal plate  134  shown in FIG. 7 a  is adapted to receive the tip  136  and or lower portion of the vial  124 . However, the vial openings in the plate  134  are not connected. Vertical plates  138  attached on edge to a third horizontal bar  135  serve as spacers and guide plate members to determine the precise height from the base plate to point of contact of the vial with the uppermost part of the notch  122  of the shim plate  118 . At least one of the plates  138  serves as a guide and locator when placed in contact with the guide arm  18  seen in FIG.  1 . If any of the fixture components become worn or misaligned, quality of the vial seal is reduced. 
     The movable heater bar assembly  44  is essentially the same as that described for the stationary heater bar assembly  32  above, the only difference being the attachment of the toggle arm connector blocks  46 , the lifting handle  52 , and the switch actuator assembly  68 . It should also be noted that both the movable and stationary heater bars are water cooled. Heater bar wiring is improved by passing the wiring through the vertical plate  14 , capturing the wiring along the heater bar groove  76 , shown in FIG. 5, where the wiring terminates at the terminal connector studs  94  located at each end of the heater bars  32 ,  44 . 
     It has been found that the heater bar assemblies  32 ,  44  may also be configured whereby the bar  72  also includes the spacer bar element  114  as an intergral piece. In which case a slit is provided between the spacer bar poriton and the upper surface of the bar adjacent to face  102  for insertion of a portion of the insulating tape  112 , thereby eliminating the need for upper brass strip  82 . This configuration reduces the number of pieces required thereby reducing inventory. 
     Obviously, pneumatic operation of the heat sealing machine described above would be advantageous. However, in the past, a completely different configuration was required by the manufacturer for pneumatic heat sealing operation requiring purchase of a new machine. However, it is much more efficient to simply provide a conversion package for attaching pneumatic actuators to the existing apparatus as seen in FIG.  8 . The pneumatic conversion only requires that the handle assembly  34  be removed and the twin pneumatic cylinder and pivotal support assemblies  200  installed. The assemblies  200  include adapter linkage and all mounting hardware, as well as air line connectors and operation valve, ready for connection to a pneumatic pressure source. 
     Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in any limiting sense.