AU592703B2 - Method of tensioning a web of packaging material - Google Patents

Description

592903 1 S F Ref: 61250 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Class Int Class On Complete Specification Lodged: Accepted: Published: Priority: *Related Art: Name and Address of Applicant: s, Fuji Machinery Co Ltd 14-10, 2-Chome, Kamejima Nakamura-ku, Nagoya Aichi

JAPAN

Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Address for Service: Complete Specification for the invention entitled: Method Of Tensioning A Web Of Packaging Material i The following statement is a full description of best method of performing it known to me/us this invention, including the 5845/3 ~1 METHOD OF TENSIONING A WEB OF PACKAGING MATERIAL BACKGROUND OF THE INVENTION This invention relates generally to a method of tensioning a web, and more particularly relates to a method of tensioning a web of packaging material in a form-fill-seal packaging machine commonly referred to as a "vertical packaging machine" or as a "horizontal packaging machine" in which a web of i packaging material is fed from a supply roll, formed into j 9. tubing, intermittently stopped, and sealed at package length 490 intervals. The invention is especially concerned with a S method of suitably tensioning a web of packaging material for the purpose of preventing slack of the web which will be developed between web feeding rolls and tubing feeding means X when the web is intermittently stopped to be sealed at packages

S'

t length intervals. The invention is also directed to the prevention of slack which will be developed between the web i d b feeding rolls and the supply roll in the event that the V diminishing supply roll is excessively overrun by the web i which is intermittently pulled forward through the web feeding rolls.

In the first place, a brief description will be given as to how the present invention method has proposed, with reference to Figure 1 illustrating a so-called vertical packaging apparatus, which is one typical type f form-fill-seal I

I

1 t i,, :4 packaging apparatus. In the apparatus illustrated, a web 14 of plastic material such as polyethelene sheet is fed from a supply roll 16 of the material over a former or web forming device 12 mounted to the upper part of a vertically extending cylindrical, hollow mandrel 10. At the former 12 the web 14 is formed into tubing, the tubing being fed downward a predetermined length and sealed by a center sealing device 18 to form a longitudinal seal on the edges overlapping in a longitudinal direction and sealed at package length intervals.

S. Articles W are supplied from upside into the tubing. Then the tubing is fed forward a predetermined length, intermittently stopped, sealed by an end sealing device 20 to form transverse seals and ultimately cut by a cutter 22 into individual St packages filled with articles (Figure The web 14 is intermittently pulled from the supply roll 16 and fed forward f toward the former 12 by a pair of web feeding rolls 24 located between the supply roll 16 and the former 12. The feeding Srolls 24 are intermittently driven for feeding the web 14 forward one package length increment in a given interval.

The increment of the web 14 fed forward by the web feeding rolls 24 is taken up and pulled over the former 12 under tension by tubing feeding means indicated generally at 26 in Figures 1 and 3 below the former 12. The tubing feeding means 26, as illustrated in Figure 2, comprises a pair of endless belts each designated 30 at opposite sides of the mandrel 2 Each of belts 30 is trained around a. pair of pulleys 28 arranged in vertical alignment at the respective side of the mandrel 10. The belts 30 are rotated in a predetermined direction for feeding downward the web 14 formed into tubing at the former 12 and thence gripped in sealing engagement with the outer periphery of the mandrel 10. In Figure 1, reference numeral 31 designates a register mark sensor for sensing register marks printed on the web 14. Reference numerals 33 and designate a guide plate and turning bars, respectively.

In the operation of form-fill-seal packaging machines of i the type just described, the web 14 may be slacken betweeen the web feeding rolls 24 and the tubing feeding means 26, and S ternrs to meander when fed forward toward the former 12.

Because of such unsmooth feeding of the web 14, therefore, the machine may have to be operated at a lower package production rate than desired. Additionally, the web feeding rolls 24 intermittently pull a package length increment of the web 14 from the supply roll 16, thereby diminishing the diameter and hence the mass of the supply roll 16 with the passage of time. Thus the resulting augmented pull tends to excessively overrun the supply roll 16, causing the web 14 to be slacken in the path from the supply roll 16 to the web feeding rolls 24. Again, because of such slack, the web 14 I may not smoothly be fed forward, reducing efficiency of operation.

3 L f -7 -4- SUMMARY OF THE INVENTION .1 '1 4: 4141 i It is the object of the present invention to overcome or substantially ameliorate the above disadvantages.

There is disclosed herein a method of tensioning a web of packaging material in a form-fill-seal packaging apparatus, wherein a web is intermittently pulled from a supply roll through web feeding rolls, and fed over means for forming it into tubing, and wherein articles to be packaged are provided in the tubing and sealing and cutting operations are performed on the tubing to seal and cut it to form packages comprising the steps of: rotating said web feeding rolls for a predetermined amount of time so as to unroll a predetermined packaging length of said web material from said supply roll; sensing the progressive diminishing of the outer diameter of S said supply roll as said web of material is unrolled from said supply roll )5 by said web feeding rolls during said predetermined amount of time; generating signals indicative of said sensed outer diameter 4 values of said progressively diminishing supply roll; using a central processing unit to determine when braking of the supply roll is required to counteract excessive overrun of the supply roll as its diameter diminishes, in dependence on said sensed outer diameter values of said progressively diminishing supply roll and values of the packaging length corresponding to one desired length for the packages to be formed and the width of the web, previously stored within said central S processing unit and to generate corresponding control signals; and 4S5 causing braking of said supply roll in response to said control I4 S signals so as to progressively retard said supply roll as said outer diameter of said supply roll progressively diminishes in order that said web material is withdrawn from said supply roll under tension.

There is further disclosed herein a form-fill-seal apparatus wherein a web is intermittently pulled from a supply roll through web feeding rolls and fed over means for forming it into tubing, and wherein articles to be packaged are provided in the tubing and the sealing and cutting operations are performed on the tubing to seal and cut it to form packages, comprising: a supply roll of said web material; web feeding rolls for withdrawing said web material from said supply roll; tt 4 4 4 4 4 C UL 4::44 m sensor means for sensing the progressively diminishing of the outer diameter of said supply roll as said web of material is withdrawn U from said supply roll by said web feeding rolls; 4, 9 0 *9 9 4 9 49 4 44S 0Q~t~ 4 9 9 a 44 4 4 44 4' 4 4 *t a a 4*44 rat,.

4 (4, 4&44(4 V 4.

-A

i i

I

f i.

j-.

BRIEF DESCRIPTION OF TH.E DRAWINGS The invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of a form-fill -seal packaging apparatus for carrying out the invention method; Figure 2 is a sectional vieW taken substantially along the line II-rI of Figure 1; Figure 3 is a schematic representation of the apparatus of Figure 1 in which the end sealing device forms a transverse seal on a tubing when the web feeding rolls and the tubing feeding means are stopped; Figures 4 to 6 are schematic representations of the overall arrangement of the apparatus for performing the invention method, showing the transmission and'disconnection of rotational force in various phases of operatioi through the apparatus; C Figures 7 and 8 are views showing different arrangements of the shifting means between the high-speed operation and the low-speed operation; and Figures 9 and 10 are schematic and symbolic diagrams of an alternative form of the invention.

DETAILED DESCRIPTION OF THE INVENTION The invention method of tensioning a web of packaging material will now be dtscribed with reference to Figures 4 to 6 which illustrate one embodiment of the apparatus for performing the method. For convenience in describing, all parts are numbered to correspond to similar parts of Figures 1 to 3, and the general description of the parts of Figures' 14 to 6 applicable to the corresponding parts of Figures 1 to 3.

j Referring first more particularly to Figure 4, there is S tV

II

r, Ts generally indicated at 40 a motor which is a common single I source of drive adapted to rotate and stop the web feeding mtrolls 24 and the tubing feeding means 26. A first rotary shaft 42 is connected at one end to the motor 40 and has a small-diameter gear 44 secured thereto. The first rotary shaft S 42 also has a large-diameter gear 46 secured thereto and spaced Li a predetermined distance from the small-diameter gear 44.

1The large-diameter gear 46 is freely rotatably carried on the rotary shaft 42 and is operatively connected to an electromagnetic clutch 48 mounted to the other end of the rotary shaft 42. Thus, on-off control of the electromagnetic clutch 48 permits mechanical connection and release (transmission Sand cut-off of power) of the large-diameter gear 46 relative to the first rotary shaft 42.

The small-diameter gear 44 normally meshes with another large-diameter gear 52 which is freely rotatably carried by a second rotary shaft 50 arranged in parallel relation to the first rotary shaft 42. The second rotary shaft 50 has secured thereto another small-diameter gear 54 which meshes with the large-diameter gear 46 on the first rotary shaft 42. The 5 second rotary shaft 50 has an electromagnetic clutch 56 mounted to one end thereof, and the large-diameter gear 52 is operatively connected to the electromagnetic clutch 56.

«Thus, on-off control of the clutch 56 permits mechanical tfe, C connection of the large-diameter gear 52 relative to the c E second rotary shaft 50. The second rotary shaft 50 has a pulley C, 58 secured to the other end thereof. Additionally, the web Sc feeding roll 24 has a rotary shaft 60 which in turn has a r pulley 62 secured to one end thereof. An endless belt 64 is trained between the pulleys 58 and 62. The rotary shaft also has an electromagnetic brake 66 connected'to one end iCc' thereof.' Thus, actuation of the brake 66 causes a .series of rotational system to stop instantly.

C C The second rotary shaft 50 has a bevel gear 68, as shown in Figure 4. Another bevel gear 70 is secured to a third rotary shaft 72 extending at right angles to the second rotary shaft 50, and meshes with the gear 68. The third rotary shaft 72 has at one end thereof a one-way roll 74 which permits transmission of driving power only in one direction and which i freely rotates in the other direction to cut off transmission of driving power. A spur gear 76 is secured to the third 8 s

A

M

II I; ii I1 it: L1

'I:

Vtli rotary shaft 72 through the one-way roll 74. Specifically, in the illustrated embodiment, the third rotary shaft 72 is driven for rotation in a clockwise direction, and the driving power in the clockwise direction causes the third rotary shaft 72 to rotate in the same direction along with the one-way roll 74. It is important to note that when the third rotary shaft 72 is stopped, the spur gear 76 is allowed to rotate in the clockwise direction; and when the third rotary shaft 72 is reversely driven, the spur gear 76 is never allowed to rotate in a counterclockwise direction.

t A spur gear 78 is secured to a rotary shaft 77.which is C fixedly connected to one end of the pulley 28 for driving the feeding belt 30. The spur gears 78, being associated with r the respective feeding belts 30 disposed diametrically on opposite sides of the mandrel 10, are connected for meshing C t, ccc engagement with each other, and one of the spur gears 78 is meshed with the spur gear 76 associated with the one-way roll c I 74. Reference numeral 80 designates a rotary encoder which c c is connected to the second rotary shaft 50 through a gear train 82 and adapted to sense and monitor rotational speeds in the rotational system.

Referring to Figures 7 and 8, shown therein is a partially modified embodiment in conjunction with the driving system of Figure 4. Specifically, Figure 7 shows an arrangement in which the first electromagnetic clutch 48 and the second electromagnetic clutch 56 are carried on the second rotary shaft 50 of Figure Power transmission between the first rotary shaft 42 and the second rotary shaft 50 are effected by means of timing pulleys 83,85 and timing belts 84,86.

To this end, only one motor 40 is used. Figure 8 shows another arrangement using two individual driving motors 88,90 in which power is transmitted through sprockets 89,91 and chains 92,94.

C£

o now be described. As shown in Figure 4, to start feeding the j CC web 14 from the supply roll 16, the first electromagnetic B clutch 48 is deactuated to thereby allow the large-diameter C• gear 46 to freely rotate relative to the first rotary shaft 42. The second electromagnetic clutch 56 is actuated to connect the large-diameter gear 52 with the second rotary 'cc shaft 50. At this time, the electromagnetic brake66 is deactuated. With these conditions existing, starting rotation C Tof the motor 40 causes the bevel gears 68 and 70 to rotate i through the small-diameter gear 42 and the large-diameter gear 52, thereby rotating the third rotary shaft 72 in a ,clockwise direction. As this occurs, the one-way roll 74 permits the spur gear 76 to rotate in a clockwise direction.

The spur gears 78 are then rotated to drive the tubing feeding means 26 and thereby effect downward feed of the web 14 on the mandrel 10. It can be appreciated that since the power Stransmission is accomplished through. the combination of the small-diameter gear 52, the tubing feeding means 26 is rotated at low speeds. Also, it can be seen that the power is transmitted from the second rotary shaft 50, via the belt 64, to the web feeding rolls 24 at low speeds. Thus, the web feeding rolls 24 and the tubing feeding means 26 are simultaneously started at low speeds to thereby tension the web 14 interposed between the web feeding rolls 24 and the tubing feeding means 26.

tct itr When the first electromagnetic clutch 48 is actuated after j Ti seconds after starting, as shown in Figure 5, the largec diameter gear 46 is mechanically connected to the first rotary iL shaft 42. At the same time as this occurs, the second electromagnetic clutch 56 is deactuated to thereby mechanically disconnect the large-diameter gear 52 from the second rotary Sshaft 50. Thereupon, the low-speed drive is switched into a high-speed drive, that is, the web feeding rolls 24. and the tubing feeding means 26 are shifted into a steady operation at synchronous high speeds. At this time, the web 14 remains 2z tensioned between the web feeding rolls 24 and the tubing feeding means 26.

When' a predetermined length of web 14 has been fed forward, it is necessary to stop the forward feed of the web 14 so that a transverse seal may be formed by the end sealing device 20. Specifically, after T2 seconds, the second

I

electromagnetic clitch 56 is actuated and the first electromagnetic clutch 48 is deactuated, as shown in Figure 4, thereby shifting the web feeding rolls 24 and the tubing feeding means 26 into a low-speed operation. Again, the web 14 remains S- 5 suitably tensioned between the web feeding rolls 24 and the "tubing feeding means.

Further, after T3 seconds, the first and second electroh magnetic clutches 48,56 are simu'.taneously deactuated and L. concurrently with this, the electromagnetic brake 66 is a actuated, as shown in Figure 6, thereby cutting off the rotation df the motor 40 to be transmitted to the second ~I rotary shaft 50 (the motor 40 being normally -otated). It is important to note that when the electromagnetic brake 66 is l actuated, the second rotary shaft 50 to which power transmission has been cut off may be instantly stopped. Also, the bevel Sgears 68,70 are simultaneously stopped, thereby stopping the S third rotary shaft 72. However, the spur gear 76 mounted to the third rotary shaft 72 through the one-way roll 74, continues to rotate for a while by virtue of the inertia force stored during the low-speed rotation in the previous step. Thus, the pair of feeding belts 30 in the tubing feeding means 26, being connected to the spur gear 76 throug'i the spur gear 78, is moved slightly by inertia before it makes a complete stop.

The web 14 formed into a tubing may be stopped after it has been imparted a required tension in a direction of feed on 12 r the mandrel 10. An optimum tension may be maintained on the web 14 interposed between the web feeding rolls 24 and the tubing feeding means 26, and during intermittent feeding of web 14, the tubular web will not meander, thereby making it possible to form fine quality packages. Further, since the web feeding .rolls 24 and the tubing feeding means 26 are started at low speeds, brought to a steady operation at high r tt 1' speeds and then shifted into a low-speed operation before S t, stopped, a predetermined' package length of the web .l °0 may be fed forward positively, enabling production of packages i C r at.a relatively high rate.

From what has been said, it will be apparent that the invention method offers the possibility of tensioning the web interposed between the web feeding rolls and the tubing feeding means by allowing the tubing feeding means to move slightly further under inertia by stopping'the tubing feeding means a little later than the web feeding rolls) when r the web feeding rolls are instantly stopped.

Figures 9 and 10 illustrate an alternate method of tensioning a web of material between the supply roll and the web feeding rolls. As may be seen in Figure 9, the supply roll 16 is supported on a rotary shaft 110 which in turn rotatably supported by bearings (not shown) to permit free rotation of the supply roll 16. The rotary shaft 110 has connected at one end thereof brake means 112 such as an 13 ii-- il.-i_ electromagnetic powder brake and a hysterisis brake so that the rotary shaft 110 and hence the supply roll 16 may be suitably braked. Specifically, when the brake means 112 is deactuated, the supply roll 16 may be freely rotated with the rotary shaft 110; and when the brake means 112 is actuated, the feeding rotation of the supply roll 16 may be braked.

Thus, the alternate method is directed particularly to that brake force which is tracked and regulated in a so-called real-time manner in proportion to the diameter of the supply t roll 16 being diminished with the passage of time.

Contacting the outer periphery of the supply roll 16 is a free roll or rotary wheel 114 pivotally connected to one end of a pivotal lever 116. The other end of the pivotal lever 116 is fixedly connected to one end of a pivotal shaft 118 carried by a bearing (not shown). The other end of the pivotal shaft 118 is connected to a gear 120, which meshes with a gear 126 secured to a rotary shaft 124 of a position 'iCI C sensing device such as a potenti.ometer 122. Apparently, as A the web 14 is pulled from the supply roll 16, the diameter of the roll body is diminished continuously with the passage of time. In this regard, the lever 116, bearing against the supply roll 16 through the rotary wheel 114, varies its angular position relative to the pivotal shaft 118. The change in angular position of the lever 116, that is the reduction in diameter of the roll body, is outputted as an angular' change signal through the pair of gears 120,126 and the potentiometer 122.

As shown in Figures 9 and 10, the output of the potentiometer 122 is fed to a central processing unit 128 through an analog-to-digital converter 130. In this regard, numerical information such as width and cut pitch of web 14 has previously been sttored in the central processing unit 128 through input means 132'such as a ten key. The central processing unit 128 compares the signal representative of the angular position C

S

r t sensed by the potentiometer 122, that is the actual reduction c tV cc t in diameter of the supply roll 16, with the data representative

CC

of the .width and the cut pitch of' web 14. Based on chis comparison, an instruction signal is processed in and outputted C r c from the central processing unit 128 to give a most appropriate c" feeding speed which is applicable to the supply roll 16 at

C

C

c C that time, the signal being fed back to the brake means 112.

It will be noted that the instruction signal values may be digitally displayed on a display unit 134 such as a CRT or t a liquid crystal display.

In the operation of the vertical form-fill-seal packaging apparatus, the web feeding rolls 24 pull a package length increment of web 14 from the supply roll 16, thereby diminishing the diameter of the supply roll 16. Unless extra countermeasures are taken, the supply roll 16 will diminish its diameter with the passage of time, thereby reducing its mass.

Between the starting and the final s.tage of the supply roll 16, a significant difference is apparent in feeding speeds of the supply roll 16, which is rotated by the web 14 being pulled forward intermittently. Because of this difference, the supply roll 16 will excessively, overrun, causing slack of web 14 in the region from the supply roll 16 to the web feeding rolls 24.

To cope with this, in the present method, the reduction in diameter of the supply roll 16 is sensed as an angular change by the potentiometer 122 in a real-time manner, the angular change being inputted into the central processing r e unit 128. The central processing unit 128 has stored therein factors, such as width and cut pitch of the web 14, which will influence on the feeding speed of the web 14 and hence, by processing the data, the central processing unit 128 may issue a mos.t suitable instruction signal at that time to brake the supply roll 16. The instruction signal is inputted into the electromagnetic powder brake 112 as a control signal to brake the rotary shaft 110 of the supply roll 16. As the braking V force increases in inverse proportion to the reduction in S LU diameter of the supply roll 16, a proper tension is always imparted to the web 14 interposed between the supply roll 16 and the web feeding rolls 24. Thus, the present method solves the problem of web slack which will be developed between the supply roll 16 and the web feeding rolls 24, thereby making it possible to feed the web at a higher rate at all times.

Claims (3)

1. A method of tensioning a web of packaging material in a form-fill-seal packaging apparatus, wherein a web is intermittently pulled from a supply roll through web feeding rolls, and fed over means for forming it into tubing, and wherein articles to be packaged are provided in the tubing and sealing and cutting operations are performed on the tubing to seal and cut it to form packages, comprising the steps of: rotating said web feeding rolls for a predetermined amount of time, so as to unroll a predetermined packaging length of said web material from said supply roll; sensing the progressive diminishing of the outer diameter of S' said supply roll as said web of material is unrolled from said supply roll by said web feeding rolls during said predetermined amount of time; generating signals indicative of said sensed outer diameter values of said progressively diminishing supply roll; t using a central processing unit to determine when braking of the r en l v\ 4 e m arniti rl +f ran -nr avg 4

4- tri. ft r P 4-ha ukiinm ii vi l L llU l I I aU F lj IUI a 1 I 4u I V V .Vuv VUIl V CA%.V OI VC VV I I uII U I LII au p j I V as its diameter diminishes, in dependence on said sensed outer diameter values of said progressively diminishing supply roll and values of the packaging length corresponding to one desired length for the packages to be If formed and the width of the web, previously stored within said central processing unit and to generate corresponding control signals; and causing braking of said supply roll in response to said control signals so as to progressively retard said supply roll as said outer diameter of said supply roll progressively diminishes in order that said web material is withdrawn from said supply roll under tension. 2. A form-fill-seal apparatus wherein a web is intermittently l pulled from a supply roll through web feeding rolls and fed over means for forming it into tubing, and wherein articles to be packaged are provided in the tubing and the sealing and cutting operations are performed on the tubing to seal and cut it to form packages, comprising: a supply roll of said web material; web feeding rolls for withdrawing sald web material from said supply roll; sensor means for sensing the progressive diminishing of the outer diameter of said supply roll as said web of material is withdrawn .Arom said supply roll by said web feeding rolls; N/16141 L~ 18 means operatively connected to said sensor means for generating signals indicative of said sensed outer diameter values of sa'd progressively diminishing supply roll; central processing means operatively connected to said signal generating means for receiving said signals and for determining when braking of the supply roll is required to counteract excessive overrun of the supply roll as Its diameter diminishes, in dependence on said sensed supply roll outer diameter value signals and values of the packaging length corresponding to one desired length of packaging to be formed and the width of the web previously stored within said central processing means to generate corresponding control signals; and 'braking means operatively connected to said supply roll of said web material for progressively retarding the rotation of said supply roll, |j in response to said control signals received from said central processing means, as said outer diameter of said supply roll progressively diminishes in order that said web of material is withdrawn from said supply roll under .r tension. 3. Apparatus as set forth in claim 2, wherein said sensor is a feeler in contact with the outer surface of said supply roll of said web Smaterial. 4. Apparatus as set forth in claim 2 or claim 3, wherein: said signal generating means is a potentiometer. I A method tensioning a web of material, substantially as hereinbefore described with reference to the accompanying drawings.

6. Apparatus for tensioning a web of material, substantially as hereinbefore described with reference to the accompanying drawings. DATED this SIXTEENTH day of OCTOBER 1989 Fuji Machinery Co Ltd r Patent Attorneys for the Applicant TSPRUSON FERGUSON