Method and Apparatus for Packaging a Collective Product, and Such Packaged Product

Abstract

System, hardware, and methods for agitating a package pre-form containing a charge of product elements thus to provide for product settling in the package pre-form before forming the final transverse seal. The product is caused to settle in the package pre-form by apply a plurality of rapid jerk-type acceleration forces to the packaging material, thus to cause rapid longitudinal and/or lateral acceleration in the packaging material.

Claims

1. A method of making a sealed package containing a charge of compound product, the method comprising: forming a tubular package pre-form by steps that include wrapping flexible packaging material around a forming tube, sealing edge portions of the packaging material together to form a longitudinal seal, and sealing other portions of the packaging material together to form a first transverse end seal; advancing the flexible packaging material along and past the forming tube using a pulling apparatus adapted to engage and pull the flexible packaging material; loading the charge of compound product into the tubular package pre-form through the forming tube; and agitating the tubular package pre-form using the pulling apparatus.

2. The method of claim 1, wherein the agitating comprises advancing the flexible packaging material in a series of jerks using the pulling apparatus.

3. The method of claim 1, wherein the pulling apparatus advances the flexible packaging material in a uni-directional manner.

4. The method of claim 1, wherein the pulling apparatus comprises a pull belt.

5. The method of claim 1, wherein the agitating begins before the loading ends.

6. The method of claim 1, wherein the agitating is carried out over an agitation period and the loading is carried out over a loading period, and wherein the agitation period at least partially overlaps the loading period.

7. The method of claim 6, wherein the agitation period substantially completely overlaps the loading period.

8. The method of claim 1, wherein the agitating is carried out over an agitation period and the loading is carried out over a loading period, and wherein the agitation period does not overlap the loading period.

9. A sealed package containing a charge of compound product, made using the method of claim 1.

10. A method of making a sealed package containing a charge of compound product, the method comprising: forming a tubular package pre-form by steps that include wrapping flexible packaging material around a forming tube, sealing edge portions of the packaging material together to form a longitudinal seal, and sealing other portions of the packaging material together to form a first transverse end seal; advancing the flexible packaging material along and past the forming tube using a pulling apparatus adapted to engage and pull the flexible packaging material; and loading the charge of compound product into the tubular package pre-form through the forming tube; wherein the advancing comprises agitating the tubular package pre-form using the pulling apparatus, the agitating adapted to settle the compound product in the tubular package pre-form.

11. The method of claim 10, wherein the agitating comprises advancing the flexible packaging material in a series of jerks using the pulling apparatus.

12. The method of claim 10, wherein the pulling apparatus advances the flexible packaging material in a uni-directional manner.

13. The method of claim 10, wherein the pulling apparatus comprises a pull belt.

14. The method of claim 10, wherein the agitating begins before the loading ends.

15. The method of claim 10, wherein the agitating is carried out over an agitation period and the loading is carried out over a loading period, and wherein the agitation period at least partially overlaps the loading period.

16. The method of claim 15, wherein the agitation period substantially completely overlaps the loading period.

17. The method of claim 10, wherein the agitating is carried out over an agitation period and the loading is carried out over a loading period, and wherein the agitation period does not overlap the loading period.

18. A sealed package containing a charge of compound product, made using the method of claim 10.

19. A vertical form fill and seal (VFFS) machine, comprising: an unwind station for receiving a roll of flexible packaging material; a forming tube around which the flexible packaging material can be wrapped; a pulling apparatus adapted to engage and pull the flexible packaging material along and past the forming tube; one or more seal stations, disposed proximate the forming tube, at which edge portions of the flexible packaging material are sealed together to form longitudinal seals, and other portions of the flexible packaging material are sealed together to form transverse end seals, thereby to form a series of tubular package pre-forms from the flexible packaging material; a drop station from which a charge of compound product can be dropped into a given one of the tubular package pre-forms through the forming tube; and a controller coupled to at least the pulling apparatus, the one or more seal stations, and the drop station; wherein the controller is configured to agitate the tubular package pre-form using the pulling apparatus to promote settling of the compound product in the given tubular package pre-form.

20. The machine of claim 19, wherein the pulling apparatus comprises a pull belt, and wherein the controller is configured to agitate the tubular package pre-form by operating the pull belt according to a series of short jerks.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] FIG. 1 is a graph representing a typical single-pull prior art velocity profile.

[0080] FIG. 2 is a regrouped, rectangular waveform illustration of the velocity profile of FIG. 1.

[0081] FIG. 3 is a graph representing a typical double-pull prior art velocity profile.

[0082] FIG. 4 is a schematic side elevation view of a packaging system of the invention, showing a step where product has been dropped into a partially-formed package to form a pre-formed tube.

[0083] FIG. 5 is a schematic side elevation view as in FIG. 4 where the top seal is being formed in the product-filled package and the bottom seal is being formed in the next trailing length of packaging material.

[0084] FIG. 6 is a schematic side elevation view as in FIGS. 4 and 5 where the filled and sealed bag has dropped onto a take-away conveyor, and the system is ready to fill the next length of packaging material.

[0085] FIG. 7 is a schematic side elevation as in FIGS. 4-6 where the next charge of product has been dropped into the next trailing length of packaging material, and the pull belts are driving the next trailing length of packaging material downwardly using the stutter step method of the invention.

[0086] FIG. 7A shows a side elevation view of one of the pull belts of FIG. 7, engaging the packaging material against the forming tube and driving the packaging material downwardly using the stutter step method of the invention.

[0087] FIG. 8 is a flow chart illustrating an exemplary set of steps used in the invention.

[0088] FIG. 8A is another flow chart, similar to that of FIG. 8, that may be used with the invention.

[0089] FIG. 9 shows a velocity/time profile using a three-step pull where the sustained maximum-velocity time periods are longer than the acceleration and deceleration time periods.

[0090] FIG. 10 shows a velocity/time profile where both the sustained maximum velocity, and the number of stutter step pulls, are increased relative to those of FIG. 9.

[0091] FIG. 11 shows a velocity/time profile where the maximum velocity time period is essentially zero.

[0092] FIG. 12 shows a velocity/time profile where the velocity is reduced to something greater than zero during the intermediate reduced-velocity portions of the stutter steps and the frequency is modified.

[0093] FIG. 13 shows a velocity/time profile having multiple sustained maximum velocities portions, separated by reduced velocity portions where velocity is at all times greater than zero and the frequency is modified.

[0094] FIG. 14 shows another velocity/time profile where the maximum velocity time period is essentially zero.

[0095] FIG. 14A shows a velocity/time profile similar to that of FIG. 14 but where there is variability in the shape of the velocity/time profile, and none of the individual stutter step jerks or pulls are identical to each other.

[0096] FIG. 15 is a timeline showing a possible scenario involving the operation of various functions of a packaging system over the course of one bagging cycle that is part of a series or stream of such bagging cycles, for a single-pull bag system.

[0097] FIG. 16 is a simple block diagram of a programmable logic controller (PLC).

[0098] The invention is not limited in its application to the details of construction, or to the arrangement of the components or methods set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various other ways. Also, it is to be understood that the terminology and phraseology employed herein is for purpose of description and illustration and should not be regarded as limiting. Like reference numerals are used to indicate like components.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0099] Turning now to FIG. 4, a packaging system 10 of the invention is controlled by a controller 12, typically a programmable logic computer or programmable logic controller (PLC). The primary activity of the system is implemented using a vertical form fill and seal (VFFS) machine 14 which is illustrated herein, but is not necessarily limited to only VFFS machines. A first guide roll 16 is positioned between a packaging material feed roll 18 and a pair of measure rolls 20 which form a nip 22 therebetween. A second guide roll 24 is located downstream of nip 22. A registration sensor 26 is positioned between second guide roll 24 and nip 22. Downstream of second guide roll 24 is forming shoulder 28 which is generally mounted above an elongate, downwardly-extending, forming tube 30 at the upwardly-disposed feed end 30A of the forming tube 30. An elongate seal-forming platen 32 is mounted in an upright orientation, intermittently pressing against forming tube 30. First and second pull belts 34 are mounted in upright orientations adjacent, and pressing against the forming tube 30, on opposing sides of platen 32 and driven so as to advance downwardly against the forming tube. First and second seal heads 36A, 36B, which may be rear and front seal heads respectively, are mounted below the downwardly-disposed exit end 30B of the forming tube 30, in opposition to each other, and are spaced closely outside a downward projection of the forming tube 30. Take-away conveyor 38 is located under forming tube 30 and under seal heads 36A, 36B. The packaging material feed roll 18 is mounted in a suitable location so as to provide a generally continuous length of rolled packaging material to VFFS machine 14. A product hopper 42 is positioned above and adjacent forming shoulder 28 so as to be able to drop product 44 into the underlying forming tube 30. Each seal head 36A, 36B includes an upper heat seal jaw 46, a lower heat seal jaw 48, and a cutting element 50 between the upper and lower seal jaws.

[0100] Packaging material 40 is selected, designed, and/or configured such that any two facing surfaces of the packaging material can be heat sealed to each other. Thus, overlapping opposing surfaces are sealed to each other to form longitudinal seals, and facing elements of a given surface are sealed to each other to form transverse seals.

[0101] FIG. 4 shows the system at the stage where packaging material has been drawn over first guide roll 16, through nip 22, past registration sensor 26, past second guide roll 24, over forming shoulder 28, and onto forming tube 30. Forming shoulder 28 and forming tube 30 have collectively formed the previously flat sheet of packaging material into a tubular orientation about forming tube 30, with longitudinal edge portions of the packaging material oriented generally vertically and facing each other, either as overlapping edge portions or as facing portions which can be formed into fin seals. Longitudinal seal platen 32 has formed a plurality of lengths of such longitudinal seals, with the lengths of the seals overlapping each other, whereby each such seal is a continuation of the next preceding longitudinal seal, thus to have formed a longitudinally-sealed tube. A bottom transverse seal 52 has been formed at the apparent leading edge of the longitudinally-sealed tube, thus to form a tubular package pre-form 53, sealed at the bottom, open at the top, and continuously longitudinally sealed from the transverse seal to a height corresponding to the top of platen 32. A first charge of product 44 has been fed/dropped from hopper 42 into the package pre-form. A second charge of product 44 is seen in FIG. 4 in the process of being fed/dropped into hopper 42 as indicated by arrows 45. The pre-form has been advanced downwardly, using a jerky stutter step-type drive motion of the invention, described in more detail following. Seal heads 36A, 36B are withdrawn away from, but are adjacent, the sides of the package pre-form. Top 54 of product 44 in the package pre-form is below the bottoms 56 of the seal jaws, and below the bottom of transverse seal area 58, the transverse seal area being illustrated by stippling in FIG. 4 between the seal jaws. The seal area desirably, and typically, would be free from, namely devoid of, product 44.

[0102] FIG. 5 shows the packaging system of FIG. 4 with heat seal heads 36A, 36B closed on the tubular package pre-form at the seal area. In FIG. 5, the lower heat seal jaws 48 are forming a top transverse heat seal 60 (see FIG. 6) across the top of the underlying length of the package pre-form and above top 54 of the contained product, thus to finish closing and sealing the package pre-form with the product contained therein to make a closed and sealed package, containing the charge of product 44. Simultaneously, cutting element 50 engages the packaging material across the width of the package pre-form above top transverse heat seal 60, thus cutting away the underlying now-fully-sealed package 62 from the overlying package pre-form 53. As also shown in FIG. 5, simultaneously with the lower heat seal jaws 48 forming the top heat seal on the underlying length of the package pre-form, upper heat seal jaws 46 are forming a bottom transverse heat seal 52 across the bottom of the next adjacent, and overlying, package unit length of packaging material, thus forming the next succeeding package pre-form.

[0103] FIG. 6 shows the packaging system of FIGS. 4 and 5 with the seal heads again withdrawn. As the seal heads withdrew from their sealing positions shown in FIG. 5, package 62 was released from the grip of lower seal jaws 48. Having been cut away from the package pre-form by cutting element 50, package 62 fell by gravity onto take-away conveyor 38. Thus, package 62 is shown on take-away conveyor 38 in FIG. 6. Also shown in FIG. 6, overlying hopper 42 has been fully recharged with the next charge of product 44, ready to be dropped into the package pre-form, and platen 32 has been advanced horizontally against the edges of the next length of packaging material, to form a continuation of the longitudinal seal in the longitudinally scaled tube.

[0104] FIG. 7 shows the next stage of the process, where the platen has been withdrawn from the packaging material at the forming tube as suggested by arrows 55, and the next charge of product has been dropped from hopper 42 into the underlying package pre-form.

[0105] A typical product which is dropped from hopper 42 is a collective product as described above, e.g., a dry food product. Examples of such dry food products are various snack products such as chip products. Potato chips, corn chips, tortilla chips, pita chips and the like are representative of such snack products. Another common product is dry breakfast cereals and other grain-related products. Still another product is popped popcorn. Such products have a number of product characteristics which make them susceptible to initially arriving in the bottom of the package pre-form in a relatively less dense condition, and which presents problems for the packager. Common characteristics may include, without limitation, one, some, or all of: [0106] The product is light weight. [0107] The product is relatively fragile, easily broken. [0108] The product is relatively dry. [0109] The product has a coefficient of friction which impedes, but does not stop, movement of the product elements relative to each other. [0110] Product configuration, from product element to product element, is non-uniform such that the product exhibits different shapes. For example, potato chips all have approximately the same thickness, but different individual chips in a given package have different lengths and widths, and the chips tend to bend/curl during cooking, and the bend/curl configurations differ from chip to chip. For example, many breakfast cereals contain multiple different ingredients, each having a different three-dimensional shape/configuration. For example, raisin bran contains both flakes and dried raisins. Furthermore, as described in more detail above in relation to popped popcorn, product densityand therefore also the volume of a charge of productmay change from one batch, or from one portion of a batch, to another, which can (if the product is not adequately mixed before measuring out each charge of product) result in excessive head space for packages containing the higher density, lower volume product charges.

[0111] Even where the product is not fragile, not light weight, not non-uniform, the product can still arrive in the package pre-form in a bulk density which is less than desired. Accordingly, increasing the bulk density of the product in the package, as well as improving the consistency of the density, package to package, is desirable for the packager.

[0112] As the product drops from hopper 42 into the package pre-form, the respective product elements lodge with respect to each other and with respect to the side walls of the package pre-form in keeping with their respective physical properties. Especially the light weight, varying configurations, and the friction properties affect the way the product elements come to rest relative to each other when first dropped into the package pre-form.

[0113] Still referring to FIG. 7, in the invention, when at least a portion of the charge of product has arrived in the package pre-form, controller 12 may issue commands to measure rolls 20 and pull belts 34 to cause the measure rolls and pull belts to begin simultaneously advancing the packaging material, as indicated by downwardly-directed arrows 64. In the invention, such advance is a series of jerky downward stutter step movements of the package pre-form between respective advances and retractions of the platen in making longitudinal heat seals. The packaging material advance is a plurality of jerks, also referred to herein as stutter steps, between platen engagements when each advance represents a unit package.

[0114] Note by inspection of the figure that situations can occur at certain times in the machine cycle where a portion (e.g. an upper portion) of a charge of product may be present in the forming tube 30, even though the entire charge of product may also be simultaneously present in the package pre-form. This is because an upper portion of the package pre-form is ordinarily wrapped around the forming tube 30. As product first begins to drop from the hopper 42 into the (empty) package pre-form, it may initially fall through and then past (out of) the forming tube 30, coming to rest and beginning to accumulate at or near the bottom of the package pre-form just above the transverse bottom seal 52. Immediately thereafter, subsequent falling product elements drop onto the accumulating mass of product (inside the package pre-form) at higher and higher positions relative to the transverse bottom seal 52, until a portion of the product charge may be present in the forming tube 30, and simultaneously present in the package pre-form, as shown. Stated differently, the package pre-form can, and often does (depending on the volume of the product being packaged), extend into the forming tube 30, and this situation can exist while the charge of product is being dumped into the package pre-form.

[0115] The jerky stutter step advance is indicated in FIG. 7 by a first series of aligned and short, upwardly-directed arrows 62 spaced from each other on the outwardly-disposed portion of pull belt 34, and a second series of aligned and downwardly-directed arrows 64 spaced from each other under transverse bottom seal 52 on the package pre-form. FIG. 7A shows pull belt 34 in side elevation view, such that arrows 62 indicate an upward direction of advance on the outwardly-disposed portion of pull belt 34 as in FIG. 7, and a downward direction of advance on the inwardly-disposed portion of the belt which presses the packaging material against the forming tube. Of course, there is insufficient time to perform any sealing operations on the package pre-form between individual jerks in a series of jerks that form a given stutter step advance. Also, each individual jerk in the series typically moves the film by a distance which is small relative to the distance moved by a conventional film pull, e.g., by less than , or less than , or less than 1/10 of the bag length.

[0116] The stutter step advance may occur only during the period when the product is being dropped into the package pre-form, or only after the entire charge of product has been dropped into the package pre-form, or the stutter step advance may occur both during and after the product drop, e.g., the stutter step advance may begin during (or even before) the period when the product is being dropped into the package pre-form, and it may end after the entire charge of product has been dropped into (and is present in) the package pre-form.

[0117] Because the invention operates with a series of jerks, and intermediate periods of lesser velocity, or no velocity, the acceleration required to maintain desired throughput rates may, as a result, exceed the limitations/capabilities of the system, in which case adjustments may need to be made to one or more of the system parameters. For example, the total time required to complete a pull may have to be increased.

[0118] Assuming, for example, a 250 mm pull in 833 ms in 5 individual pulls, using the equations shown above, the calculation is as follows:

Length per segment=250/5=50 mm.

Pull time per segment=83/5=16.67 ms.Velocity Calculation

VMAX can then be determined as follows:

Distance=(2VMAXT)/3.

[0119] With Distance=50 mm=0.3086 revolutions=308 counts and T=16.67 ms.

VMAX=(3Distance)/(2 T)=924 counts/33.34 ms=27.71 counts/ms=27,710 counts/sec.

Acceleration=VMAX/(T/3)=277103/16.67=4,986,803 counts/sec/sec.

Deceleration=Acceleration=4,986,803 counts/sec/sec.Acceleration and Deceleration Calculations

[0120] The above calculations show that the acceleration and deceleration requirements can become excessive and impose restrictions on the amount of film which can be pulled in the desired amount of time within the response limits of the system.

[0121] Certain steps can be taken to resolve the situation, for example and without limitation, one, some, or all of: [0122] 1) decrease the packaging material pull length per package unit length; [0123] 2) increase the packaging material pull time per package unit length in the machine cycle; [0124] 3) decrease the number of programmed jerk moves per package unit length in the packaging material pull cycle; [0125] 4) decelerate to a speed greater than zero; [0126] 5) increase the energy input into the system; and [0127] 6) replace the power supply and other appropriate machine elements with elements having greater energy input rate capacities.

[0128] One example of a flow chart that can be used, for example in a PLC or other controller in any of the described packaging systems, to accomplish the desired results of settling the collective product inside the package pre-form by short stutter step pulls is shown as FIG. 8. The flow chart of that figure is self-explanatory and requires no further explanation in view of the foregoing detailed explanation of the disclosed stutter step agitation method. Another flow chart, similar to that of FIG. 8, is provided in FIG. 8A. The FIG. 8A flowchart is also self-explanatory, and it makes more explicit the fact that the number of individual stutter step pulls (NP) can be associated with any given film pull. For example, if the packaging system is set up for double-pull bags, then the number NP of stutter step pulls (short pulls) may pertain to the first film pull, or to the second film pull, or both, for such package. Still other methods can also be used, depending on the capabilities afforded in the hardware being used to control the system.

[0129] As the measure rolls and pull belts engage the packaging material and affect the stutter step/jerk motion of advancing the packaging material, a number of motion-related effects related to product settling, which we refer to as motion elements, can occur within the advancing package pre-form.

[0130] A first motion element is the primary motion of the packaging material, which creates a first motion differential between the packaging material and the contact product elements which are in contact with the packaging material.

[0131] A second motion element is the motion which is thus imparted to those contact product elements whereby those contact product elements, themselves, move.

[0132] A third motion element is a second motion differential which is created between the contact product elements and those non-contact product elements which are not in contact with the packaging material and which are in contact with the contact product elements.

[0133] A fourth motion element is the motion of those so contacted non-contact product elements, which is imparted by the contact product elements.

[0134] A fifth motion element is the motion imparted to all the remaining non-contact product elements as those product elements come into contact with a product element which is already in motion.

[0135] From the foregoing description, the reader will appreciate that both the ordinary film pull and the disclosed stutter step pulls typically move the flexible packaging material in only one direction, namely, forward, or downward as represented in the orientation of FIGS. 4 through 7A. That is, at substantially all times during the course of a film pull or stutter step pull when the packaging material has a non-zero velocity, i.e. when such material is not momentarily at rest, the velocity of such material may be in the same direction, which we designate the forward direction. The magnitude of the velocity can increase and decrease, and thus acceleration of the packaging material can be bi-directional (forward and backward, or positive and negative), but the velocity itself is substantially uni-directional (including at some times zero velocity) during the course of the machine packaging cycle.

Example System

[0136] A Hayssen Ultima VFFS machine is equipped with an Omron programmable logic controller (PLC) as the control system, uniquely programmed to operate according to the invention. The exemplary control system employs stepper motor technology to drive the measure rolls and pull belts. The configuration is illustrated in FIGS. 4-7 and 7A. The control system includes a motion control system for control of the stepper motors. The measure rolls are assigned as the master axis and the pull belts are set up in a follower mode to run at speeds which match the surface speeds of the measure rolls, thereby accommodating the mechanical ratio between the measure rolls and the pull belts. This ratio can be adjusted by the operator as needed to compensate for e.g. packaging material slip due to humidity, temperature, film characteristics, and other factors.

[0137] The pull belts follow the commanded position of the measure roll axis in an open loop configuration using stepper motors.

[0138] In the alternative, servo motors, or stepper motors with encoders attached for position feedback, can be used in a closed loop configuration with the measure roll axis designated as the master axis.

[0139] Another approach is to attach an encoder to the master axis and allow the pull belt axis to follow the encoder rather than the commanded position of the master axis. This forms a closed loop system which is very much like the closed loop servo system.

[0140] Conventionally, a unit package is pulled in one or two, optionally three or more, pulls depending on the length of the longitudinal back seal. If the package length is longer than the platen seal bar, the pull typically consists of two pulls, each of which approximates half of a unit package length. The longitudinal back seal is performed at the end of each pull when the packaging material is not moving, such that the ends of the respective longitudinal seals overlap each other, the lengths of the overlapping seals depending on the lengths of the packages being formed.

[0141] If the package length is equal to, or greater than, the length of the longitudinal platen seal bar, the invention comprehends the use of two pulls, or more, with a stutter step motion coincident with at least one of the pulls, to help the settling of product in the package pre-form. Restated, any time the package material is driven, with product in the package pre-form, the stutter step/jerk type drive is used unless multiple pulls are used, or the stutter function is disabled by the operator, for a given package unit.

[0142] Thus, an answer to the settling problem is found by breaking the continuous normal pull into a series of shorter pulls or jerks between engagements of the longitudinal platen against the packaging material to form the longitudinal seals. In the series of short jerks, which series is referred to as a stutter step profile, each individual jerk in the series moves the film by a distance which is small relative to the distance moved by a conventional film pull, e.g., by less than , or less than , or less than 1/10 of the bag length.

[0143] For example, if it is desired to pull a 20 inch bag, rather than making a single 20 inch pull, the invention makes a series of short, jerky pulls, for example 20 one-inch pulls, or ten two-inch pulls, or five four-inch pulls, or six 3.33-inch pulls, each pull coming to a complete stop, or at least reducing pull speed, before starting the next pull. Since the machine controller, e.g. a programmable logic computer or programmable logic controller (PLC), is capable of dividing the pull by any number, using a variety of maximum velocities, a variety of minimum velocities, a variety of acceleration rates, a variety of deceleration rates, the film pull can be divided into any number of segments, recognizing that the greater the number of pulls, potentially the greater the total pull time, which may impact the total cycle time for forming, filling, and sealing the package.

[0144] The velocity of a given one of the pulls of the packaging material in forming a given package in the prior art is, for example and without limitation, commonly represented as a -- profile. The first third of the pull starts at zero velocity and accelerates to the maximum velocity (VMAX). The second third of the pull is accomplished at the maximum calculated velocity for that pull, and the third and final portion of the pull decelerates the packaging material pull from the maximum velocity to zero velocity. This is the motion standard for the velocity calculations required to produce a package of a desired length in the prior art. The same time and velocity principles apply in the invention.

[0145] As illustrated in prior art FIGS. 1-3, for any given packaging material advance, the area under the time/velocity graph represents the linear distance of advance of the packaging material. Thus, for a given specified distance of advance, whatever the profile of the graph, the area under the graph must be the same. So for a stutter step advance rather than a single pull as in FIG. 1, either maximum velocity can be increased, or time can be increased, or acceleration and/or deceleration rates can be increased; or any combination of such elements can be used. Furthermore, the minimum velocity may in some cases be some value greater than zero for some or all of the stutter steps excluding, of course, the final step. A full stop of the packaging material must be achieved at least once for each unit package in order for the platen and seal heads to be able to form the longitudinal and transverse seals.

[0146] The velocity/time profile for such an advance of the packaging material using a three step, jerky/stutter step, pull is illustrated in FIG. 9, where the sustained maximum-velocity time periods are longer than the acceleration and deceleration time periods. In FIG. 9, a series of three substantially similar stutter step pulls takes the place of a conventional film pull such as that of FIG. 1 (or such as either one of the film pulls in FIG. 3). The maximum velocity for the velocity profile of FIG. 9 is VMAX(9), and the overall jerky stutter step advance lasts for a total pull time T. The pull time T in FIG. 9 may differ from the pull time T of FIG. 1 (and from the pull time T of FIG. 3), and the maximum velocity VMAX(9) may differ from the maximum velocity VMAX of FIG. 1 (as well as VMAX of FIG. 3); however, VMAX(9) and T in FIG. 9 are selected such that the area under the curve of the FIG. 9 velocity profile substantially equals the area under the curve of the velocity profile of the film pull in FIG. 1 (or the area under the curve of the velocity profile of either one of the film pulls in FIG. 3). This condition ensures that the packaging material advances the same distance over the course of the jerky stutter step advancee.g., at least one bag length, or at least or of the bag lengthas the distance traveled by the packaging material over the course of the conventional film pull of FIG. 1 (or either one of the film pulls in FIG. 3). Consequently, for example, VMAX(9) of FIG. 9 may be selected to be greater than VMAX of FIG. 1, or T in FIG. 9 may be selected to be greater than T of FIG. 1, or both.

[0147] FIG. 10 shows a velocity/time profile for a jerky stutter step advance similar to that of FIG. 9, but where the sustained maximum velocity VMAX(10) is increased relative to the sustained maximum velocity VMAX(9) of FIG. 9 over the same time period T, and the number of stutter steps has been increased, which results in increased rates of acceleration and deceleration relative to FIG. 9. In FIG. 9, a series of three substantially similar stutter step pulls takes the place of a conventional film pull such as that of FIG. 1 (or such as either one of the film pulls in FIG. 3). Just as in FIG. 9, VMAX(10) and T in FIG. 10 are selected such that the area under the curve of the FIG. 10 velocity profile substantially equals the area under the curve of the velocity profile of the film pull in FIG. 1 (or the area under the curve of the velocity profile of either one of the film pulls in FIG. 3). This condition ensures that the packaging material advances the same distance over the course of the jerky stutter step advancee.g., at least one bag length, or at least or of the bag lengthas the distance traveled by the packaging material over the course of the conventional film pull of FIG. 1 (or either one of the film pulls in FIG. 3). Consequently, for example, VMAX(10) of FIG. 10 may be selected to be greater than VMAX of FIG. 1, or T in FIG. 10 may be selected to be greater than T of FIG. 1, or both.

[0148] FIG. 11 shows a velocity/time profile of still another jerky stutter step advance, but where the maximum velocity time period is essentially zero, and where the maximum velocity is VMAX(11). In FIG. 11, a series of six substantially similar stutter step pulls takes the place of a conventional film pull such as that of FIG. 1 (or either film pull of FIG. 3). Just as in FIGS. 9 and 10, VMAX(11) and T in FIG. 11 are selected such that the area under the curve of the FIG. 11 velocity profile substantially equals the area under the curve of the velocity profile of the film pull in FIG. 1 (or the area under the curve of either film pull of FIG. 3). This condition ensures that the packaging material advances the same distance over the course of the jerky stutter step advancee.g., at least one bag length, or at least or of the bag lengthas the distance traveled by the packaging material over the course of the conventional film pull of FIG. 1 (or either film pull of FIG. 3). Consequently, for example, VMAX(11) of FIG. 11 may be selected to be greater than VMAX of FIG. 1, or T in FIG. 11 may be selected to be greater than T of FIG. 1, or both.

[0149] FIG. 12 shows a velocity/time profile for still another jerky stutter step advance that may be suitable for some sets of conditions. In this case, the profile exhibits a maximum velocity VMAX(12), and an intermediate minimum velocity VINT(12) greater than zero during the intermediate stutter steps/jerks, and the frequency is modified relative to FIGS. 9-11, i.e., more individual stutter step pulls are included in the series of FIG. 12. In FIG. 12, a series of eight stutter step pulls, the middle six of which are substantially similar to each other, takes the place of a conventional film pull such as that of FIG. 1 (or either film pull of FIG. 3). The values of VMAX(12), VINT(12), and T in FIG. 12 are selected such that the area under the curve of the FIG. 12 velocity profile substantially equals the area under the curve of the velocity profile of the film pull in FIG. 1 (or the area under the curve of either film pull of FIG. 3). This condition ensures that the packaging material advances the same distance over the course of the jerky stutter step advancee.g., at least one bag length, or at least or of the bag lengthas the distance traveled by the packaging material over the course of the conventional film pull of FIG. 1 (or either film pull of FIG. 3). Consequently, for example, VMAX(12) of FIG. 12 may be selected to be greater than VMAX of FIG. 1, or T in FIG. 12 may be selected to be greater than T of FIG. 1, or both.

[0150] FIG. 13 shows a velocity profile for another jerky stutter step advance that may be suitable for some sets of conditions. This profile has multiple sustained maximum velocity portions, at a maximum velocity VMAX(13), separated by reduced velocity portions, at an intermediate velocity VINT(13), where the velocity is at all times (between 0 and T) greater than zero, and the frequency is modified relative to FIGS. 9-12, i.e., a different number of individual stutter step pulls are included in the series of FIG. 13. In FIG. 13, a series of seven stutter step pulls, the middle five of which are substantially similar to each other, takes the place of a conventional film pull such as that of FIG. 1 (or either film pull of FIG. 3). Just as in FIG. 12, VMAX(13), VINT(13), and T in FIG. 13 are selected such that the area under the curve of the FIG. 13 velocity profile substantially equals the area under the curve of the velocity profile of the film pull in FIG. 1 (or the area under the curve of either film pull of FIG. 3). This condition ensures that the packaging material advances the same distance over the course of the jerky stutter step advancee.g., at least one bag length, or at least or of the bag lengthas the distance traveled by the packaging material over the course of the conventional film pull of FIG. 1 (or either film pull of FIG. 3). Consequently, for example, VMAX(13) of FIG. 13 may be selected to be greater than VMAX of FIG. 1, or T in FIG. 13 may be selected to be greater than T of FIG. 1, or both.

[0151] In general, the profiles of FIGS. 9-13 show that a given length of packaging material can be advanced while using a wide variety of stutter step profiles. The variety of the available profiles which can be used with the stutter step method is limited only by the mechanical limits of the machine drives and the imagination of the user in setting up the instruction set in the software program which is entered into controller 12. Such wide variety of profiles allows the user to adapt the stutter step profile, and thus the stutter step pulls, to the particular product being packaged while ensuring a balance of

[0152] release of product from the seal area,

[0153] optimized product settling in the package,

[0154] use of limited package material length,

[0155] consistency of package results, and

[0156] acceptable quality control.

[0157] The calculations herein provide the key elements of the pull, the maximum velocity of each pull, and the minimum velocity of each jerk/stutter step as well as acceleration and deceleration factors for each pull. If no registration is required by printing on the packaging material, such calculated profile will operate the system, dispensing the desired package unit length each cycle. Where registration is required, registration sensor 26 senses a registration mark on the packaging material and alerts controller 12, which adjusts the drives to the measure rollers and/or the pull belts, thus to adjust the position of the registration mark relative to the cut-off of the finished, closed and sealed package.

[0158] Where more than one pull of packaging material, and more than one platen engagement are used for a given package unit, at least one, but not necessarily all, of the platen engagements, to form a longitudinal seal comes after a stutter step advance. Namely, some of the pulls/advances can be non-stutter step pulls/advances where multiple platen engagements are used for a given package unit. Accordingly, the stutter step jerky advance is used after at least a portion of the charge of product has been fed into the package pre-form, and may not be used during an advance where no product has yet been fed into the package pre-form.

[0159] Thus, for example, for a two-step advance of the packaging material, where the packaging material is advanced two times and two longitudinal seals are made, for a given package unit, the first advance may take place immediately after at least a portion of a charge of product elements has been fed into the package pre-form. Given that the product is in the package pre-form, and an objective of the jerky stutter step advance is to settle the product and/or remove product from the seal area, that first advance may follow a stutter step profile while the second advance may follow a profile more like that of FIG. 1. In the alternative, the first advance may be a conventional advance as in FIG. 1 and the second advance may be a jerky stutter step advance. So long as at least one of the advances is a stutter step advance, the objectives of product settling and/or product being freed from the seal area can be met.

[0160] In any event, the settling provided by the invention can be achieved without any mechanical device touching any outside surface of that portion of the packaging material which extends past the exit end of the forming tube, and without any physical touching of the packaging material by a human operator.

[0161] In a further embodiment, not illustrated specifically in the drawings, the advance of the packaging material can start as a conventional acceleration to maximum velocity as in FIG. 1, progress at constant VMAX velocity for a portion of the VMAX time shown in FIG. 1, and proceed as a jerky stutter step portion of the VMAX time, subsequently decelerating to zero velocity as in FIG. 1. Such embodiment thus envisions a velocity profile as in FIG. 1, modified by a jerky stutter step velocity profile as shown in for example any of FIGS. 9-13, for a portion, but less than all, of the time shown as VMAX in FIG. 1. Such modification can occur at any point along the time axis of FIG. 1, though typically, the jerky stutter step modification starts after velocity has reached VMAX.

[0162] Changing any pull parameter, such as pull length, pull degrees, machine speed, acceleration rate, deceleration rate, minimum velocity, maximum velocity, time at maximum velocity, time at minimum velocity, or print registration, will cause the system to recalculate the remaining pull parameters.

[0163] As used herein, a jerk advance of the packaging material means either both rapidly accelerating the packaging material and then decelerating the packaging material, or rapidly accelerating the packaging material, rapidly slowing the acceleration, and then again rapidly accelerating the packaging material.

[0164] In the alternative, a jerk can be a strong force rapidly applied to the packaging material in the direction of advance of the packaging material so as to rapidly apply acceleration tension to the film, such as a force calculated to reach a VMAX packaging material acceleration in the anticipated pull time, but wherein the packaging material is prevented from advancing by a brake system. Such jerk force causes sufficient e.g. lateral flexing of the packaging material in the package pre-form to cause displacement of any product from the seal area and to at least initiate product element settling in the package pre-form.

[0165] At least first and second jerks are employed either before or after, or both before and after, the formation of a given one of the longitudinal seals. Thus, where a jerk-type advance of packaging material is used, at least two jerks are used to advance or otherwise tension the packaging material after formation of a given longitudinal seal and before formation of the next longitudinal seal.

Additional Discussion

[0166] We now provide some additional discussion of aspects of the inventive techniques and systems set forth in the detailed description above. Much of this additional discussion simply emphasizes or otherwise repeats information that is explicit or implicit (or both) in the foregoing description.

[0167] The settling techniques and systems described herein preferably employ the same mechanism that is used to advance or pull the packaging material through the VFFS machine, but they control or drive that mechanism in a rapid sequence of short, strong accelerations or decelerations or both, to impart a jerking motion or agitation to the package pre-form and its contents, and thus promoting settling of the product in such pre-form. (Agitation of the package pre-form by other means, such as by the use of mechanical vibrating devices that contact the bottom, side, or any outer surface or other surface of the package pre-form can thus be eliminated, or, if desired, such other means of agitation can be used in combination with the disclosed settling techniques and systems.) FIG. 14 shows a velocity profile, similar to those of FIGS. 9-13, for a jerky stutter step advance that may be suitable for some sets of conditions. In this figure, the jerky stutter step advance, which takes the place of a conventional film pull such as that of FIG. 1, is a series of four substantially similar stutter step pulls, with a maximum velocity time period of essentially zero, and with a maximum velocity of VMAX(14).

[0168] The onset of the jerky stutter step advance occurs at a time that is delayed relative to time=0. Furthermore, the time axis is labeled both in terms of machine degrees, and in terms of milliseconds. The time values given in the figurewhere the jerky stutter step advance begins at 10 machine degrees or 55 msec, and ends at 50 machine degrees or 275 msecare realistic for the following specific but non-limiting conditions: [0169] machine cycle rate=1.980 seconds/bag, which corresponds to slightly more than 30 bags/min; [0170] 1 machine degree=5.5 msec; and [0171] bag length=200 mm, where only one film pull (as modified by the disclosed stutter step technique) is used.
The duration of the jerky stutter step advance is 40 machine degrees or 220 msec, as indicated by the total pull time T depicted in the figure. Given this value for T, and assuming simple, uniform acceleration and deceleration for each of the four substantially similar stutter step pulls, the value of VMAX(14) can be calculated in order to ensure that the area under the curve of the velocity profile equals the pull length, which in this case is the bag length of 200 mm.

[0172] In one approach, we recognize that since the entire stutter step pull or advance is made up of four individual, and substantially similar, stutter step pulls, each stutter step pull must advance the packaging material by 200 mm/4=50 mm. Furthermore, each stutter step pull is represented by one triangular-shaped portion of the profile. Each such triangular-shaped portion can be reconfigured into a rectangle of equal area, the rectangle having a height of VMAX(14) and a width of 5 machine degrees (or 27.5 msec). The area of this rectangle is VMAX(14)*27.5 msec, which must equal the 50 mm length calculated above. Solving for VMAX(14), we get a value of 50 mm/27.5 msec, or about 1.8 mm/msec.

[0173] We can also calculate the acceleration and decelaration associated with the stutter step pulls, which acceleration and deceleration may for example be supplied by one or more stutter step motors coupled to the pull belts in contact with the packaging material. If we assume each triangular shape of the velocity profile is symmetrical, with equal magnitudes of acceleration and deceleration, we can then recognize that the velocity of the packaging material changes from 0 to VMAX(14), i.e., from 0 to about 1.8 mm/msec in 27.5 msec, for an acceleration of about 0.066 mm/msec.sup.2 (and a deceleration of about0.066 mm/msec.sup.2). By appropriately applying these parameters to the control algorithm of the packaging system, we can generate a pull velocity profile consisting of four 50 mm stutter step pulls in 40 machine degrees, or 220 milliseconds, substantially as shown in FIG. 14.

[0174] In some cases it is desirable or necessary to introduce variability into the stutter step advance. An example of such variability is shown in FIG. 14A. The velocity/time profile of the packaging material in this figure is similar to that of FIG. 14, but where variability is added, such that none of the individual stutter step jerks or pulls are identical to each other. The individual stutter step pulls may differ from each other in terms of maximum velocity, minimum velocity, maximum velocity time period (i.e., the dwell time (if any) at the maximum velocity), minimum velocity time period (i.e., the dwell time (if any) at the minimum velocity or at an intermediate velocity), time or duration of the individual stutter step pulls, and furthermore, the acceleration and deceleration (changes in velocity with time) need not be constant or smooth for any of the individual stutter step pulls. FIG. 14A illustrates several ways in which individual stutter step jerks in a series of jerks can differ: the first and second stutter step jerks have shorter durations than the third and fourth stutter step jerks; the maximum velocity of the first stutter step jerk is greater than that of the second and fourth jerks, and even greater than that of the third jerk; and the maximum velocity time period of the first, second, and fourth stutter step jerks is substantially zero, whereas that of the third jerk is nonzero and substantial. The jerk-to-jerk variability may be programmed into the operation of the packaging machine and system. However, even with such variability, the area under the velocity/time profile is still equal to the distance advanced by the packaging material over the course of the jerky stutter step advance, e.g., at least one bag length, or at least or of the bag length.

[0175] Of course, it is also possible, and simplest, to configure the packaging system so that the individual stutter step pulls, in a series of such pulls that form a stutter step advance, are substantially identical to each other, as shown in FIGS. 9, 10, 11, and 14. In cases where the minimum velocity for stutter step pulls between the first and last such pull is non-zero, such as in FIGS. 12 and 13, then the intermediate stutter step pulls (i.e., all such pulls except for the first and the last) may all be substantially identical to each other, and may have substantially the same maximum velocity, and the same acceleration and deceleration, as the first and last such pulls.

[0176] In order to make the most efficient and effective use of the time allocated to the stutter step advance, it is desirable to maximize the number of jerks over the course of the pull. This can be done by using a velocity/time profile whose maximum velocity time period (the dwell time at the maximum velocity) is zero or substantially zero (see e.g. FIGS. 11, 12, and 14), and whose intermediate minimum velocity (the relative minima in the velocity profile not including the beginning and end of the stutter step advance) is non-zero (see e.g. FIGS. 12 and 13). Of all the velocity/time profiles shown in the figures, the profile of FIG. 12 best illustrates the combination of these two features in one profile.

[0177] To maximize the productivity of the packaging machineand minimize the cycle time required to process one bag or package of productit is also desirable to begin or initiate the stutter step advance as early in the machine cycle as possible, e.g., while product is being loaded or dropped into the open-ended package pre-form, and before the entire charge of product is contained in such pre-form. In such cases, depending upon factors such as the type of product being loaded, the speed with which the product is dropped into the package pre-form, the size of the charge of product, the bag length, the total pull time T of the stutter step advance, and so forth, the stutter step advance may be finished by the time product loading is complete (and the entire charge of the product is contained in the pre-form), while in other cases the stutter step advance may not be finished but may continue or extend beyond such time as the product loading is complete.

[0178] In this regard, the relationship between the time when the stutter step advance (agitation to promote product settling in the package pre-form) is occurring and when product loading and other machine or system processes are occurring in the context of one complete machine cycle is best illustrated in FIG. 15. FIG. 15 is a timeline showing a possible scenario involving the operation of various functions of a packaging system over the course of one entire bagging cycle, for a single-pull bag system. The timeline illustrates the general operation of selected functions of a VFFS machine that employs the stutter step settling technique as disclosed above. The various functions are depicted as simple line segments on a timeline to help the reader better understand relationships that may exist between the onset, duration, or termination of one function and the onset, duration, or termination of other functions of the machine.

[0179] The timeline of FIG. 15 is labeled both in terms of machine degrees, for ease of programming, and in terms of milliseconds. The timeline depicts one cycle of operation of a VFFS machine, starting at 0 degrees (and 0 msec) and ending at 359 degrees (and 1000 msec). The value of 1000 msec assumes a machine throughput of 60 bags/minute, or 1 bag per second. If the machine throughput was reduced to 30 bags/minute, the endpoint of the timeline would change to 2000 msec, but the endpoint in machine degrees would remain the same, i.e., 359 degrees. The throughput of the machine can of course be selected as desired, within permissible limits of fill speed, film tension, seal formation time, and so forth, and is usually selected as the fastest speed and greatest throughput possible while still maintaining an acceptably high sealed package quality and sufficiently low reject rate. For reasons that will become more apparent below, the single machine cycle at issue is shown in the context of an immediately preceding machine cycle, and an immediately following machine cycle, which the reader will understand to represent only a few in a long series of machine cycles.

[0180] The functions shown in FIG. 15 are intended to be neither exhaustive nor limiting, but merely representative of selective aspects of one possible machine embodiment. Thus, additional machine functions not shown in FIG. 15 can be performed, and one or some of the machine functions included in the figure may be omitted, in some cases. The reader will also understand that the various functions depicted in the single machine cycle at issue in FIG. 15 can, if desired, be replicated in the immediately preceding machine cycle, and in the immediately following machine cycle, and indeed in all the machine cycles in the series, if the same type of package is being produced by each such machine cycle.

[0181] In FIG. 15, segment 1502 represents a film advance, beginning at time t1 and ending at time t2. Segment 1504 represents agitation of the film (packaging material) and as much of the product as is contained in the package pre-form, to promote product settling. Segment 1504 begins at time t3 and ends at time t4. A series of short arrows 1503, drawn close to the segment 1502, represents the series of jerky stutter step pulls that create the agitation of segment 1504, such stutter step pulls collectively making up at least part of the film pull of segment 1502. Segment 1506, beginning at time t5 and ending at time t6, represents the period during which the charge of product in the hopper is released and allowed to fall through the hopper opening into the package pre-form. In some cases discussed further below, this hopper dump period can extend into the immediately preceding machine cycle, as indicated by the extension 1506 to the segment 1506, where the extended segment 1506 begins at time t5 and ends at time t6, or at any time between t5 and t6 as appropriate depending on the product drop time. Segment 1508, beginning at time t7 and ending at time t5, represents the period during which the (now closed) hopper is filled with a new charge of product. Segment 1510 represents the period during which the heated platen presses against overlapping edges of the flexible packaging material to form the longitudinal seal of the packaging tube pre-form. Segment 1510 begins at time t9 and ends at time t10. Segment 1512 represents the period during which transverse seals are formed by closing the heat seal jaws such as those depicted schematically in FIG. 5. In particular, a lower heat seal jaw forms a top (transverse) seal in the package that has just been filled and agitated, and an upper heat seal jaw forms a bottom (transverse) seal in the (currently empty) packaging tube pre-form upstream of the current package. Segment 1512 begins at time t11 and ends at time t12. Finally, segment 1514 represents the period during which a knife or other cutting device cuts transversely through the packaging material to separate the now-filled and sealed current package from the next package pre-form to be filled. Segment 1514 begins at time t13 and ends at time t14.

[0182] The start and end times of the various line segments in the figure are shown to be separated from each other for generality and for purposes of illustration so that the various times can be given the unique labels t1, t2, t3, etc. However, the reader will understand that some of the labeled times can be the same or substantially the same. For example, t1 can equal t3, and t2 can equal t4, such that the film pull function (segment 1502) and the agitation function (segment 1504) occur at the same time periods. The time difference t4t3 equals the total pull time T of the stutter step advance as discussed above.

[0183] Of particular significance is the relationship between the agitation function and the hopper dump (or product fill) function. In the prior art, where a bottom shaker plate was used to agitate and settle the contents of the packaging tube pre-form, agitation did not begin until the full charge of product was contained in the open-ended package pre-form. (Furthermore, the localized nature of the agitation at the bottom of the bag tended to result in product damage or breakage.) However, in the disclosed technique, at least some of the agitation can occur while the product is still being loaded into the packaging tube pre-form (e.g., while some product elements are still being dropped into the pre-form), and as the pre-form is being lowered by operation of the film advance function towards the take-away conveyor 38 as seen in FIGS. 4-7. By operating the system in this fashion, with overlap between the agitation function and the hopper dump (or product fill) function, the time required for each bagging cycle can be reduced, and the productivity of the machine system (e.g. in bags/minute) can be correspondingly increased.

[0184] Thus, if we refer to the time during which the agitation occurs as an agitation period (such as segment 1504), and the time during which product loading occurs as a loading period (such as segment 1506), then the agitation period preferably overlaps the loading period. That is, at least some of the agitation preferably occurs while the open-ended package pre-form is being filled, or before the last product element of the charge of product is contained in the package pre-form. In some cases, the agitation period and loading period may satisfy one or both of the following relationships: the agitation period overlaps at least half of the loading period; and the loading period overlaps at least half of the agitation period (e.g. overlaps at least half of the total number of jerky stutter step pulls, assuming such jerky pulls are of substantially equal duration).

[0185] Despite the preference for an overlapping agitation and loading period, in some circumstancesdepending on details of the collective product, flexible packaging material, package dimensions, and features and limitations of the VFFS machineit may be neither practical nor desirable to have such an overlap. Furthermore, the relationship of the agitation period (such as segment 1504) to the loading period (such as segment 1506), and to other functions represented by segments in FIG. 15, may be very different from the relationships depicted in that figure.

[0186] For example, there are many situations when running a VFFS machine in which it is highly desirable to begin the product loading (hopper dump) while the heat seal jaws are closed to form the bottom transverse seal of the package pre-form, or even to begin such loading slightly before the heat seal jaws close (in view of the short time delay between the moment when the first product elements begin falling from the hopper and the moment those product elements reach the bottom of the package pre-form). In this way, we can avoid transferring to the newly formed, virgin transverse bottom seal the full force of the product being dropped, and can instead cushion at least some of that force by the heat seal jaws, the closed heat seal jaws also serving to shield the virgin bottom seal from the full brunt of such force and prevent a failure of such seal. This can be of particular concern when the flexile packaging material is or comprises a polyethylene film, since a seal formed by two polyethylene film portions can be quite weak at the moment the heat seal jaws open due to the gelatinous, molten condition of the seal, before the heated seal region is allowed to thoroughly or even partially cool and harden.

[0187] Consequently, the loading period (see segment 1506) can be shifted relative to its position shown in FIG. 15. As indicated in FIG. 15 by the extended segment 1506, the starting point t5 (the beginning of product loading/hopper dump for the depicted machine cycle) can occur even before t=0, that is, it can occur during the immediately preceding machine cycle, at any time after the jaws close in such preceding cycle (or coincident with the jaws closing or even slightly before, taking into consideration the elapsed time for product to drop from the hopper to the package pre-form), at a time that is analogous to the time t11 in the depicted machine cycle but that occurs before t=0. The ending point t6 of the product loading period can then occur at any time after t5, dependent on factors such as the type of product, the drop distance from the hopper to the package pre-form, the machine speed, and so forth. In this regard, the ending point t6 of the product loading period may also occur in the preceding machine cycle (before t=0 in FIG. 15), whereupon there is no overlap of the loading period with the agitation period, or the point t6 may occur between time t3 and t4, whereupon there is overlap of those two periods. The reader should also note that to the extent t6 is interpreted to represent the moment when the hopper gate closes, then the actual time when product loading is completethat is, when the last product element from the product charge reaches the end of its travel and actually falls onto the mass of other product elements that have collected in the partially formed package pre-formmay occur after t6.

[0188] Of the many possible situations the machine designer may encounter using the disclosed agitation techniques and machine cycles, we note the following three: [0189] (1) the starting point t5 (the beginning of product loading period for the bag that becomes fully sealed in the depicted machine cycle) can occur during the machine cycle at issue, i.e., after t=0, as depicted in FIG. 15, and the ending point t6 can occur during or after (as shown in FIG. 15) the agitation period, such that the product loading period and the agitation period substantially overlap with each other; or [0190] (2) the starting point t5 can occur before the machine cycle at issue, i.e., during the preceding machine cycle and before t=0, while the ending point t6 occurs during the agitation period (segment 1504) of the machine cycle at issue, e.g., after t3 and on or before t4, such that the product loading period and the agitation period again overlap with each other; or [0191] (3) both the starting point t5 and the ending point t6 can occur before the machine cycle at issue, i.e., during the preceding machine cycle and before t=0, or t6 may alternatively extend into the current machine cycle and occur after t=0 but before t3, whereupon in either case there will be no overlap of the product loading period with the agitation period, and the entire charge of product would be present in the package pre-form before the start of the agitation.

[0192] The reader should therefore be careful in interpreting the machine cycle depicted in FIG. 15. As explained above, the loading period during which the product charge is dropped from the hopper into the open-ended package that is agitated during the depicted segment 1504 and that becomes fully sealed (top-sealed) during the depicted segment 1512 may actually start (and in some cases end) in the immediately preceding machine cycle, before t=0. In such cases, another product charge (loading period) would typically occur during the machine cycle depicted in FIG. 15, but that charge would be for a subsequent package immediately upstream of the package that becomes fully scaled in the machine cycle at issue (such subsequent package being agitated and fully sealed in the immediately following machine cycle of FIG. 15). Many different configurations of programming the termination cycle of the machine can be used to ensure the cycle is stopped after clearing the last filled bag from the partially formed tube without producing an empty bag on the first machine cycle.

[0193] The reader will note that the single VFFS cycle of operation of FIG. 15 comprises two main sections, namely, a film pull section, during which the flexible packaging material is being pulled and advanced, and a sealing section, during which the flexible packaging material is being sealed by the platen, the seal jaws, or both, and hence the film is stopped relative to the forming tube.

[0194] The functions shown in FIG. 15, as well as other functions not depicted in the figure but discussed elsewhere herein, are preferably governed by an electronic controller such as a PLC. A simple block diagram of a PLC is provided in FIG. 16. The PLC typically includes a microprocessor or other processor, memory, and input and output interfaces as shown. The PLC also typically includes a power supply that powers the processor and the interfaces. A communications interface couples to the processor, and allows for programming of the processor by an external programming device. The processor couples directly or indirectly to one or more input devices through the input interface, and it couples directly or indirectly to one or more output devices through the output interface. The actions or functions carried out by the packaging machine or system, such as those shown in FIG. 15, can be programmed into the PLC and stored in its memory.

[0195] Examples of output devices the PLC may couple to include: a pull belt (or pair of pull belts) to accomplish the film advance and stutter step agitation; actuator(s) to move the pull belt(s) into and out of contact with the packaging material; a measure roll; a hopper device or devices to accomplish dumping one load or charge of the collective product from the hopper into the tubular construct by opening the hopper, as well as filling another load of the product into the hopper; a heated platen seal bar to accomplish longitudinal sealing of the tubular construct, and associated actuator(s); transverse seal jaws to accomplish transverse or end sealing of the tubular construct; and a knife, heated wire, or other known device to cut through the flexible packaging material between transverse seals, so that individual bags or packages can be produced from the continuous roll of packaging material. Examples of input devices the PLC may couple to include one or more: film registration sensors; temperature sensors; weight sensors; jaw closed indicators; low film indicators; pushbuttons; selector switches; operator touch screens; program entry devices; and the like.

[0196] Although the invention has been described with respect to various embodiments, this invention is also capable of a wide variety of further and other embodiments within the spirit and scope of the appended claims.

[0197] Those skilled in the art will now see that certain modifications can be made to the apparatus and methods herein disclosed with respect to the illustrated embodiments, without departing from the spirit of the instant invention. And while the invention has been described above with respect to the preferred embodiments, it will be understood that, in light of the disclosure here, the invention can be adapted to numerous rearrangements, modifications, and alterations, and all such arrangements, modifications, and alterations are intended to be within the scope of the appended claims.

[0198] To the extent the following claims use means plus function language, it is not meant to include there, or in the instant specification, anything not structurally equivalent to what is shown in the embodiments disclosed in the specification.