Forming and Filling Flexible Plastic Packaging

The invention relates to forming and filling flexible plastic packaging.

In form and fill packaging apparatus, a web of plastic is advanced through a vacuum thermoformer (where the plastic web is formed to provide receptacles for receiving articles), a filling station (where articles are placed in the formed receptacles), a sealer (where a second sheet is placed over the filled receptacles and sealed to portions of the web around the receptacles to provide covers), and a cutter (where the plastic web is cut at portions between receptacles into separate packages).

In such apparatus different thermoforming methods have been employed, e.g., negative forming (in which a vacuum in a female mold draws heated film into the desired shape against the female mold, with or without assistance from positive pressure on the other side of the plastic), positive male forming (in which a vacuum in a male mold and positive pressure applied on the other side of the plastic draw the heated film into the desired shape against the male mold), and male plug-assisted negative forming (in which a vacuum in a female mold and a mechanical male plug on the opposite side of film are used, with or without an optional sandwich heater).

Such apparatus has been used to form both rigid and flexible receptacles, the former in general having walls that are 8 to 50 mils in thickness (depending on the plastic and application) and maintain their shape, the latter in general having walls that are less than 8 mils in thickness and readily flex and change shape. The differences in size and properties of rigid vis-a-vis flexible walls result in differences in the responses of the plastics to heat and force and in the types of thermoforming procedures employed. Flexible film thermoforming conventionally involves simple application of vacuum to easily draw the heated plastic to the mold; there often is, however, substantial stretching of the plastic, resulting in uneven reduction in wall thickness. Rigid wall thermoforming may very well involve procedures employing assistance from positive pressure in addition to vacuum and has also involved a two-step procedure of first providing a light vacuum to provide initial contour and thereafter providing both vacuum and pressure to force the film into the shape of the mold.

In one aspect the invention features automatically supplying products assembled at an assembler to a filling station of a form and fill packaging line by using a transporting line that receives the products one-after another as assembled and presents them in groups at the filling station. A transfer mechanism then transfers the articles one group at a time to corresponding receptacles formed in a web of plastic at the filling station. In preferred embodiments the transporting line includes a gate for selectively removing articles from it and directing them to a hopper for temporary storage and a reentry mechanism for causing the articles in the hopper to reenter the transporting line. The transporting line includes a track on which the articles are maintained in a predetermined orientation as they move along the track. There is a conveyor belt at the end of the track for presenting the articles at the filling station. The conveyor belt carries the articles in two rows to the filling station, and there are two tracks for carrying the articles to the conveyor belt. The articles are syringes that have wings that are supported by spaced parallel horizontal track portions and have vertically oriented bodies between the track portions during transport.

In another aspect the invention features inspecting articles prior to transfer in groups to receptacles in order to identify defective products and selectively remove products so that only groups containing defect free products are transferred. In preferred embodiments defective articles removed from the conveyor are transferred to one bin and defect-free articles are transferred to another. The transfer mechanism waits while the conveyor incrementally moves articles to the location for transfer to the packaging line until there is a complete group of defect-free articles.

In a further aspect the invention features transferring a group of products on a conveyor to a receiving station, using separately movable product engagers to change the relative positions of the products in the groups with respect to each other (by moving the relative positions of the product engagers) prior to dropping the products off at the receiving station. In preferred embodiments the product engagers are vacuum engagement members provided on the ends of longitudinally extendable cross-arms. The ends of the cross-arms are pneumatically actuated to an extended stop position and spring-returned to a retracted position. The cross-arms are supported on a robot that is capable of movement along three orthogonal axes.

In yet a further aspect, the invention features providing more uniform plastic wall thickness in flexible receptacles formed in a plastic web in a vacuum thermoformer by initially providing a first pressure difference on opposite sides of the heated plastic web positioned in the mold to provide an initial contour with substantially uniform stretching, and thereafter applying a second, larger pressure difference to form the plastic into its desired shape. The more uniform thickness permits use of a thinner web of plastic material for a given desired wall thickness in the flexible product, and the two step procedure greatly reduces stretching and associated weakened material. In preferred embodiments, both a male mold and a female mold are used, and a light vacuum is applied in the female mold to provide the first pressure difference. Vacuum is applied in the male mold, and air pressure is applied in the female mold to provide the second pressure difference.

Other advantages and features of the invention will be apparent from the following description of a preferred embodiment thereof and from the claims.

The drawings will be briefly described first.

FIG. 1 is a diagrammatic plan view of form and fill packaging apparatus and associated transporting line according to, the invention.

FIG. 2 is a diagrammatic elevation of a robot used in the FIG. 1 apparatus to transfer syringes from a supply belt to formed receptacles.

FIG. 3 is a diagrammatic perspective view of an article pickup mechanism of the FIG. 1 apparatus.

FIG. 4 is a diagrammatic bottom plan view of the FIG. 3 pickup mechanism.

FIG. 5 is a diagrammatic vertical sectional view of an engagement foot of the FIG. 3 mechanism shown engaging a syringe.

FIG. 6 is a diagrammatic vertical sectional view of a heater and portions of multiple-receptacle molds of a thermoformer of the FIG. 1 apparatus in position during an initial step of a forming operation.

FIG. 7 is a diagrammatic vertical sectional view of a heater and portions of multiple receptacle molds of the FIG. 1 apparatus in a later step of the forming operation.

Referring to FIG. 1, there is shown form and fill packaging apparatus 10 used in conjunction with syringe assembler 11 and transporting line 13, for transporting assembled syringes 18 for packaging at apparatus 10.

Form and fill apparatus 10 includes vacuum thermoformer 12, for forming web of plastic 14 advanced from supply roll 15 through it so as to provide formed receptacles 16 for receiving syringes 18 at downstream filling station 19. Seal and cover unit 20 is positioned to provide a cover over filled receptacles 16, and cutter 22 is positioned to cut the formed, filled, and sealed web into individual packaged products 24 containing five syringes 18 each.

Transporting line 13 includes in line tracks 25, 27 on which syringes 18 are transported with their wings extending outward over spaced horizontal portions of tracks 25, 27, the syringe bodies being vertically oriented in the space between the two portions of the tracks. Orienting rolls 61 capture syringes 18 in horizontal orientation and introduce them vertically into track 25. Diverter 23 splits the syringes coming from syringe assembler 11 on track 25 into two streams, one along the continuation of track 25 and one along track 27. Downstream of diverter 23 on tracks 25, 27 are chute gates 29 for selectively discharging syringes into hoppers 31. Each hopper 31 has an associated elevator 51, rotary disk bowl feeder 35, and orientation rolls 37 (to place syringes in vertical orientation) for returning syringes in hoppers 31 to their respective tracks 25, 27, as desired. Syringes are moved along tracks 25, 27 by upstream star wheel conveyors 39 and downstream star wheel conveyors 41. Track 25 has a one-half C end section to discharge chute 43 to reorient syringes 18 to a horizontal position and deliver syringes 18 horizontally to the left hand belt of infeed conveyor belt 26. Track 27 similarly has a one-half C end-section and associated chute 145 for delivering syringes in a horizontal manner to the right hand belt of infeed conveyor belt 26. Each belt of conveyor belt 26 has troughs 28 that are appropriately spaced for pick up by robot 30 (an Adept robot) and discharge into receptacles 16. Visual inspection monitor 45 is along belt 26. At the end of belt 26 is two compartment bin 49 having one compartment for good syringes and one for defective syringes and a mechanism (not shown) for selectively directing good and defective syringes to their respective compartments.

Robot 30 and multiple pickup member 32 of loading station 19 are positioned near the junction of infeed belt 26 and the web of formed receptacles 16, to load syringes 18 from belt 26 into receptacles 16. Conveyor 47 and robot 245 are adjacent to the end of belt 29, carrying packaged products 24 from cutter 22.

Referring to FIG. 2, robot 30 includes rotatable main shaft 33, primary arm 34 connected to it, secondary arm 36 rotatably connected to arm 34, and shaft 38. Shaft 38 is mounted for vertical movement on arm 36 and carries, on its lower end, bracket 40, for mounting to pickup member 32. Referring to FIGS. 2, 3 and 4, pickup member 32 includes flange 34, for attaching to bracket 40, and cross arms 36 secured at respective ends to four pads 88, each of which has ten rubber feet 41 in position to engage syringes 18. Referring to FIG. 5, each foot 41 has a U-shaped recess 42 and vacuum passage 44, leading to recess 42 and connected to vacuum tubes 46. Robot 245 carries a multiple pickup member and rotatable arms (not shown) that is similar to member 32, except that its feet are shaped like suction cups, and its cross arms are longitudinally extendable.

Referring to FIGS. 6 and 7, sandwich heater 48 and portions of water-cooled male mold 50 and female mold 52 used to form a receptacle 16 in vacuum thermoformer 12 are shown. Molds 50, 52 include passages 54 for selectively providing vacuum or positive pressure to region 56 between them.

In forming receptacles 16 in web 14, web 14 is advanced from roll 15, heated at heater 48 (FIGS. 6 and to, e.g., about 80.degree. C. to 90.degree. C., and thereafter advanced to position between male and female molds 50, 52. Heated web 14 is subjected to a light vacuum applied at female mold 52, causing a difference in pressure on opposite sides of web 14 that urges web 14 to begin assuming the shape of female mold 52 with uniform stretching (FIG. 6). Thereafter vacuum is applied at male mold 50 and positive pressure is applied at female mold 52 (FIG. 7), causing a larger difference in pressure (and in the opposite direction) and web 14 to move into contact with water-cooled (e.g., about 65.degree. F.) male mold 50 continuously along its surface. When the plastic contacts the cooled mold, it quickly cools in the desired shape. High quality mold contact is provided by the combined vacuum and air pressure. The two-step procedure has about a 3-5 second cycle, with about 1/4 to 1/2 second in the first step, depending on the plastic and thickness. The two-step procedure greatly reduces stretching and the resulting weakened material and provides more uniform wall thickness in the resulting formed receptacle. Thinner, less expensive stock can thus be used while maintaining desired, minimum thicknesses. E.g., use of 4.5 mil K resin (butadiene-styrene polymer) plastic web results in a minimum wall thickness of 1.5 mils in receptacles 16, which is significantly better than the 0.75 mil minimum thickness resulting from 6.5 mil thick starting material when using a prior process.

After a group of receptacles 14 has been formed, web 14 is advanced to move a fresh portion of the web into thermoformer 12 and to move twenty formed receptacles 16 into position at filling station 19 for simultaneous filling with a group of twenty syringes 18.

Syringes 18 are assembled at syringe assembler 11 and discharged to orienting rolls 61 one-at-a-time in horizontal orientation as they are assembled. Syringes 18 are vertically oriented at rolls 61 and received on track 25, where the syringes maintain the vertical orientation with the wings extending over spaced horizontal members of track 25. Star wheel mechanism 39 pushes syringes between its two wheels along track 25. At diverter 23 some of the syringes are diverted to track 27. The syringes continue along tracks 25, 27 and are delivered at chutes 43, 145 in horizontal orientation to the left- and right-hand rows of troughs 28, receiving an additional push at star wheels 41, 43.

In the event that syringe assembler 11 works faster than form and fill apparatus 10 or there is a problem requiring temporary shutdown of line 10, syringes 18 can be discharged and temporarily stored into hopper 31 and later incorporated back into the feed to infeed belt 26 at a time when form and fill line 10 is operating faster than assembler 11 or at a time when assembler 11 is not operating. The discharge of syringes into hopper 31 is controlled by chute gates 29. When the syringes reenter tracks 25, 27, they are raised by elevator 30 to rotary disk bowl feeder 35, which feeds the syringes 18 to orienting rolls 37 at which the syringes are placed in their vertical orientation with the wings on opposite sides of an opening between horizontal track members. Hoppers 31 can also be manually loaded with previously assembled syringes in the event of failure of syringe assembler 11.

Syringes delivered to troughs 28 of infeed belt 26 are advanced toward form and fill line apparatus 10 and are scanned by inspection station 45 to determine if there are any defective syringes (for example, whether the spacing between the wings and the plunger is within specifications, and whether all parts are present). The left- and right-hand belts of conveyor belt 26 operate synchronously when defective parts are not detected. Twenty syringes 18 are transferred at a time by robot 30 in four groups of five. If inspection station 45 identifies a faulty syringe, it is dropped into bin 47 along with any other syringes that would prevent transfer of a group of twenty defect free syringes; for example, if the defective syringe was the fourth one from the front on the right-hand side of a group of twenty to be transferred, then the right-hand belt advances four increments, discharging the defective fourth syringe and the three syringes before it on the right-hand belt into the bin. The gate in bin 47 directs the first three defect free syringes to one compartment and the defective fourth syringe to another.

In making the transfer of syringes 18 from belt 26 to receptacles 16, pickup member 32 is lowered into position over infeed belt 26 by vertical movement of shaft 38, and a vacuum applied to feet 41 causes engagement of syringes 18, two feet 41 engaging each syringe 18. Pickup member 32 is then raised by movement of shaft 38 and moved into the position shown in FIG. 1 by relative rotation of arms 34, 36 and rotation of primary shaft 33. Pickup member 32 is then lowered, and the vacuums are disengaged, permitting syringes 18 to fall into their respective receptacles 16. In travel of syringes 18 from assembler 11 to receptacles 16, syringes 18 maintain predetermined orientations during travel and are captured at all times.

As web 14 advances, the filled receptacles 16 are moved to seal and cover unit 20, where a cover sheet is sealed to the portions of web 14 between and around the receptacles. As web 14 advances further, the loaded, covered, and sealed receptacles are then vertically and horizontally cut at cutter 22 to provide individual packaged products 24 of five syringes each. Robot 245 (similar to robot 30) transfers sealed packaged products 24, four at a time, to four boxes 58 on conveyor 47, alternating the orientation of each layer, and extending arms 36 before releasing packaged products 24 in boxes 58 to provide spacing for boxes 58. After a set of boxes 58 has been loaded, conveyor 47 moves a new set of four boxes 58 into position. Packaged products 24 can be sterilized by electron beam, ethylene oxide, or radiation sterilization and reliably maintain their integrity and sterilization, owing to the wall thickness.

Other embodiments of the invention are within the scope of the following claims.