GB2275244A - Drive arrangement for rollers in strip packaging apparatus - Google Patents

Abstract

An apparatus is provided for forming elongate strips each having a plurality of longitudinally spaced product containing compartments using a continuous length of base material and a continuous length of lidding material. The apparatus performs the steps of forming a plurality of longitudinally spaced pockets in the base material, introducing product into the pockets and sealing the lidding material to the base material, and optionally severing means for trimming excess edges material from the assembly. At least one of the forming means, sealing means and severing means comprises a pair of rotatable rollers adapted to engage the base material or base and lidding materials as the case may be, in a nip defined between the rollers. A drive transmission means is also provided for the pair of rollers comprising a first drive member L rotatable with one of the rollers, a second drive member M rotatable with the other of the rollers, a third drive member N in driving engagement with the second drive member M, and a fourth drive member P in driving engagement with both the first and third drive members L, N. The rollers may be taken out of engagement with one another whilst maintaining engagement between the drive members. While out of engagement, the rollers may be replaced by rollers of a different size for use in producing strips of different length. As shown, gears L, M, N, P drive the forming rollers and similar "square" arrangements of four gears F, G, H, R and A, B, C, D drive the severing rollers and the sealing rollers. <IMAGE>

Description

APPARATUS This invention relates to an apparatus for forming elongate strips each having a plurality of longitudinally spaced compartments with product, for example powder1 therein. More particularly, it relates to the filling of cavities which are provided at intervals along an elongate base material, and subsequently closing those cavities, by a cover material, to produce an assembly of base and cover materials having sealed compartments each filled with product, the assembly being severable into elongate strips.

The invention has particular application to the situation where the cavities are defined by the blisters of blister packs, but is applicable to cavities defined in other ways. Blister packs are used, inter alia, to hold doses of medicament in powder form, for example medicament which is to be inhaled by a patient. However, it must be understood that the invention is also applicable to strips which are to contain other forms of powder, or products other than powder, e.g. liquid or individual articles such as tablets.

EP-A-474466 describes an apparatus in which blisters formed in an elongate base foil are filled with powder by urging the blisters, with their open sides facing generally downwards, into a reservoir of powder1 and then withdrawing the base foil, still with the open sides facing generally downwards, from the reservoir, the powder remaining in the blisters during withdrawal. The base foil is then covered with a lidding foil, which is heat-sealed thereto. The base foil material, in which the blisters are formed, and the lidding foil material, are both fed into the apparatus as continuous strips, and a continuous heatsealed assembly results. Subsequently, the assembly can be severed into shorter strips each containing a predetermined number of blisters and thus a predetermined number of doses of powder.Attention is directed to EP-A474466 for further details of the construction and operation of this apparatus.

The apparatus described in EP-A-474466 can only produce severed strips of one predetermined length. To alter an apparatus constructed to produce strips of one length so as to produce strips of some other length would require substantial parts of the apparatus to be disassembled, various of the components to be replaced by altemative components, and the apparatus to be reassembled. This would be a major undertaking. However, it would be desirable for the apparatus to be so constructed that to change from one strip length to another could be carried out quickly and easily, and without any major replacement of parts. This would enable a single apparatus to be used to produce strips having different numbers of doses, as and when required.

According to the present invention there is provided an apparatus for forming elongate strips each having a plurality of longitudinally spaced, productcontaining compartments, using a continuous length of base material and a continuous length of lidding material, the apparatus comprising forming means arranged to form a plurality of longitudinally spaced pockets in the base material, means for introducing product into each of the pockets, sealing means arranged to seal the base material with its filled pockets to the lidding material, to form an assembly having the said compartments therein, and, optionally, severing means arranged to trim excess edge material from the assembly, wherein at least one of the forming means, sealing means and severing means comprises a pair of rotatable rollers adapted to engage the base material or base and lidding materials, as the case may be, in a nip defined between the rollers, the apparatus further comprising drive transmission means for the pair of rollers which comprises a first drive member rotatable with one of the rollers, a second drive member rotatable with the other of the rollers, a third drive member in driving engagement with the second drive member, and a fourth drive member in driving engagement with both the first and third drive members, means being provided for taking rollers out of engagement with one another whilst maintaining the aforementioned engagements between the drive members.

Preferably, the drive members are constituted by gears. In a preferred embodiment of the invention, each of the forming means, sealing means and severing means comprises a respective pair of rotatable rollers which is driven as just described by a respective set of four drive members. However, providing such a drive transmission means has advantages even where the apparatus is only intended to produce strips of a single length, since it enables the pair of rollers concerned to be taken out of contact with one another without losing registration. This is explained further below.In the accompanying drawings: Figure 1 shows diagrammatically an apparatus substantially according to EP-A-474466; Figure Ia is a view taken in the direction of arrow "A" in Figure 1, showing a detail thereof on a larger scale; Figure 2 shows a gear and roller train employed in the apparatus of Figure 1, in the operative position; Figure 3 shows the gear and roller train of Figure 2, with one of the rollers moved to an inoperative position; Figure 4 shows the gear train of Figure 2, modified in accordance with the present invention to enable two different lengths of strip, for example 60dose strips and 28-dose strips, to be produced, the train being in a position to produce the longer of the two lengths; Figure 5 shows the train of Figure 4, but in the position enabling it to produce the shorter of the two lengths;; Figure 6 shows a forming roller used in the case of the configuration of Figure 4 to form the blisters, or pockets, required for the longer length of strip; and Figure 7 shows a forming roller required to produce the pockets for the shorter length of strip.

In the apparatus shown in Figure 1, a continuous length of base foil 1 is fed via a cleaner 2 to a pair of forming rollers 3 and 4. Roller 3 is provided with an array of pins (not shown) extending outwardly from the surface thereof, and roller 4 is provided with a mating array of depressions (not shown), with each pin being aligned with a respective depression and causing a pocket to be formed in the base foil.

The base foil, with its pockets formed therein1 passes through a detector 5 where any defects such as pin holes and splits are detected, and thence around a roller 6 which serves to tension the base foil, and which can be adjusted so as to achieve registration of the base foil on a sealing roller (described below).

The base foil then passes to a filling station 7. This comprises a nondriven filling wheel 8 which is rotatable about a horizontal axis, and a powder bowl 9 which is rotatable about a vertical axis and which contains a supply of powder therein. The bowl 9 is vertically adjustable, and for convenience is shown in the drawing as having its upper edge below the bottom of the roller 8.

In use, however, the roller 8 would dip into the powder contained in the bowl 9, so that powder is urged into the pockets of the base foil, which have their open sides facing downwardly.

The base foil, its pockets now filled with powder, then passes over a bridge 10. As it does so, it is first cleaned by a cleaning wheel 11 which serves to remove surplus powder from the areas of foil between the blisters. The surface of the wheel II is provided for this purpose with a plurality of flexible fingers 11 a spaced around the perimeter thereof, and this can be seen in Figure I a. After passing the cleaning wheel, the foil passes a cam-operated test pocket emptier 12. This extracts the powder from selected pockets, and transfers the powder to a weigher, where a check is carried out to ensure that the weight of powder is that which the pocket should contain, to within predetermined limits of tolerance. The provision of test pockets is described further below with reference to Figures 6 and 7.

The base foil is then fed to the nip formed between a pair of sealing rollers 13 and 14, to which is also fed a continuous length of lidding foil 15. The upper sealing roller 13 is heated to cause the base foil and lidding foil to be heat-sealed to one another. The lower sealing roller 14 is provided with recesses in which the pockets engage, and a sensor 25 monitors registration of the pockets with the recesses and, if necessary, causes registration to be adjusted by means of the roller 6. A foil clamp 16 is provided, which is used to clamp the assembly of base and lidding foils when the machine is stopped and the roller is pivoted away from contact with roller 14 (see below), so there is no loss of pocket registration with roller 14 or loss of foil tension downstream of roller 14.

The sealed assembly of base foil and lidding foil pass over a tensioner 17 before reaching a pair of slitting rollers 18 and 19 where the edges portions of the assembly are severed from the remainder, to leave an assembly of the desired width. A foil retention roller 20a comprising a mechanism 20, is used to assist in threading the assembly between the rollers 18 and 19. The roller 20a is movable into and out of contact with the roller 19, for example by means of an air cylinder (not shown). When the machine is in normal operation the roller 20a is out of contact with the roller 19. However, at the start of operation, when the leading end of the foil assembly is to be fed between the slitting rollers 18 and 19, the foil retention roller 20a is brought into contact with the roller 19 and the leading end of the foil assembly is pushed between them.Rotation of the roller 19 then carries the foil assembly forwardly so that it passes between rollers 18 and 19. The reason for providing the foil retention roller 20a is that the rollers 18 and 19 have to be provided with very sharp knife edges to sever the side portions of the foil assembly from the remainder thereof, and it would be hazardous for an operator to have to insert the foil assembly directly between them.

After passing the slitting rollers1 the assembly is wound up by suitable means (not shown), for severing into strips of the desired length at a later stage.

Alternatively, the assembly may be severed into such strips after it leaves the slitting rollers and without first being wound up.

Figure 1 also shows a cleaning device 21 for cleaning the lower sealing roller.

Figure 2 shows a gear train which can be used to drive the forming rollers 3, 4, the sealing rollers 13, 14 and the slitting rollers 18, 19, if the apparatus is to be used to produce only strips of a single length. For convenience, the individual gears are denoted by the letters A to M. Gears bearing the numeral "1" are at a first level with respect to the plane of the paper, gears bearing the numeral "2" are at a second level, and gears bearing both numerals extend over both levels or comprise a pair of gears, one at each level, which rotate in unison. The following is a key to the identity of the gears: A: transmission roller.

B: rotates with heat sealing roller 13.

C: rotates with heat sealing roller 14.

transmission roller.

transmission roller.

F: rotates with slitting roller 19.

G: rotates with slitting roller 18.

H idler gear, available to drive a mechanism for severing the sealed foil assembly with strips of the desired length, should that be provided in the apparatus.

idler gear, drives cleaning wheel II.

K: transmission gear.

L: motor driven gear, rotates with forming roller 4.

M: rotate with forming roller 3.

The various rollers all have the same outside diameter, and in each case it is substantially equal to the pitch circle diameter of the gear to which it is attached. It is to be noted that the gear B or the roller to which it is attached, is pivotally connected to the gear A, or the roller to which it is attached, by an arm 22. The axis of the gear B is thus movable along an arc whose centre is the axis of the gear A. This makes it possible to bring the roller 13 into and out of engagement with the roller 14, whilst keeping the gears A and B in mesh with one another. This is shown in Figure 3. The importance of this is that when the apparatus has to be stopped for whatever reason, it is essential to bring the sealing rollers 13 and 14 out of engagement with one another, since otherwise overheating would take place.However, it is highly desirable that, in so doing, the registration between the roller 13 and the other rollers in the apparatus should not be lost, since otherwise considerable work would be needed to reestablish that registration before operation could recommence. By keeping the gear B in constant mesh with the gear A, even when the rollers 13 and 14 are not in engagement, this registration is maintained. No readjustment is necessary when rollers 13 and 14 are brought back into engagement with one another. As mentioned in the key above, gear L is driven by a motor, and this provides motive power to the rest of the gears. In the case of gear B, this is driven from gear C, via gears D and A, whenever the motor is running. When rollers 13 and 14 are in engagement with one another it is also driven from gear C via the rollers.

Figures 4 and 5 show how, according to the invention, the gear train illustrated in Figures 2 and 3 can be modified so as to make it possible to produce strips of more than one length. Referring first to Figure 4, this shows a gear train in an arrangement for carrying out the same operation as the gear train of Figures 2 and 3, namely the production of strips having a sixty-dose length. As can be seen, this comprises all the gears of Figures 2 and 3, together with some additional gears. The gears L and M associated with the forming rollers are supplemented by gear P, which is in mesh with gear L, and gear N, which is in mesh with both gear M and gear P. Gear M, or the roller to which it is attached, is connected to gear N by an arm 23, by means of which the roller attached to gear M can be moved along an arc into and out of engagement with the roller attached to gear L, whilst the gear M remains permanently in mesh with gear N.

The gears F, G and H associated with the slitting rollers are supplemented by a gear R which is in mesh with gears F and H. Gear G, or the roller to which it is attached, is pivotally connected to gear H by an arm 24, so that the slitting roller to which gear G is attached can be moved along an arc into and out of engagement with the other slitting roller, whilst the gear G remains permanently in mesh with gear H.

It can be seen from Figure 4 that each of the pairs of rollers, namely the forming rollers, sealing rollers and slitting rollers, is associated with a set of four meshing gears with their axes arranged at the corners of a quadrilateral (in this case substantially a square), with a roller at each corner normally in driving engagement with a gear or roller at the neighbouring comers. The shape is not precisely a square, because the pitch circles of the gears must overlap in order for the gears to mesh, whereas the peripheries of the rollers merely touch one another. It can also be seen that in each case the pair of rollers can be taken out of engagement with one another while the gears remain in engagement with each.

The significance of the gear arrangement just described can be seen by comparing Figure 5 with Figure 4. Figure 5 shows the same gear arrangement as Figure 4. However, each of the rollers has been replaced with a larger diameter roller, which is shown in broken lines. All of the rollers continue to be driven from the gear L, gear B being driven by gear A, gear G being driven by gear H, and gear M being driven by gear N.

The gear arrangements of Figures 2 to 5 are described and shown on the basis that there are gears at two different levels, "1" and "2". However, alternatively the gears could all be at the same level, in which case under some circumstances each of the four gears in each "square" might mesh with both its neighbours.

Figures 6 and 7 show respectively two forming rollers 4, the roller of Figure 6 being that required to produce 60-dose length strips, and the roller of Figure 7 being that required to produce 28-dose strips. In the case of Figure 6, approximately 320 degrees of its surface is occupied by sixty-one recesses arranged at equal pitches and intended to form sixty-one pockets spaced along the length of a strip. One of these pockets, namely the pocket at either one end or the other, is intended to be emptied by the test pocket emptier 12, thus leaving sixty doses in the strip finally produced. The remaining approximately 60 degrees of the roller, which constitutes 13 pitch lengths, is unrecessed, and is there to provide an un-pocketed tail at the beginning and end of the strip.

The roller shown in Figure 6 is of a size which produces one 60-dose strip for each rotation thereof. If a roller of the same diameter were to be used to produce 28-dose strips, this would be extremely wasteful, both in terms of material and manufacturing time, since between each strip there would be a substantial length of material which would not be used and which would go to waste. Figure 7 shows a roller which is slightly larger in diameter than the roller of Figure 6 and which has, over its surface, two recessed portions, each with twenty-nine recesses to form twenty-nine pockets (one of each set of twenty-nine to be emptied by the test pocket emptier 12), and two unrecessed lengths, each to form a tail portion at the start of one strip and the end of another. It is these larger rollers which are shown in Figure 5.

Use of the gear train shown in Figures 4 and 5 makes it possible to alter from the production of one strip length to another by dismounting one size of forming, sealing and slitting rollers, and mounting another size. There are some consequential adjustments required elsewhere in the machine, but these are not of a major nature. The changes involved are: (a) The rotational speed of the drive motor is preferably kept unaltered, so the linear foil speed is different for the two sizes of rollers. The speed of rotation of the powder bowl 9 therefore needs to be adjusted so that the linear speed of the powder, at the location where the base foil is being urged into the powder1 is substantially equal to the linear speed of the foil.

(b) The cleaning wheel 11 needs to be replaced with a wheel having a different arrangement of flexible teeth to suit the number of recesses in the forming roller 4 and their disposition around that roller.

(c) The operation of the test pocket emptier 12 needs to be adjusted. For an apparatus in which either one strip or a pair of strips is to be produced for each rotation of the forming rollers, the test pocket emptier can be conveniently operated by a cam which has a double lobe profile. The cam is arranged to rotate in synchronism with the forming rollers, and produces two operating signals per rotation. When only one strip is being produced for each rotation of the forming rollers, the test pocket emptier is arranged to ignore alternate signals from the cam, so that it empties only one pocket for each rotation of the forming rollers, whereas when two strips are being produced for each rotation of the forming rollers1 both signals from the cam are acted on.

(d) Since, as mentioned, the foil speed is different for the two sizes of rollers, the temperature of the upper sealing roller 13 needs to be adjusted to suit the speed.

(e) The foil clamp 16 on the sealing roller 14 needs to be adjusted to suit the roller concerned.

(f) The foil retention mechanism 20 for the slitting roller 19 needs similarly to be adjusted.

Claims (5)

1. An apparatus for forming elongate strips each having a plurality of longitudinally spaced, product-containing compartments, using a continuous length of base material and a continuous length of lidding material, the apparatus comprising forming means arranged to form a plurality of longitudinally spaced pockets in the base material, means for introducing product into each of the pockets, sealing means arranged to seal the base material with its filled pockets to the lidding material, to form an assembly having the said compartments therein, and, optionally, severing means arranged to trim excess edge material from the assembly, wherein at least one of the forming means, sealing means and severing means comprises a pair of rotatable rollers adapted to engage the base material or base and lidding materials, as the case may be, in a nip defined between the rollers, the apparatus further comprising drive transmission means for the pair of rollers which comprises a first drive member rotatable with one of the rollers, a second drive member rotatable with the other of the rollers, a third drive member in driving engagement with the second drive member and a fourth drive member in driving engagement with both the first and third drive members, means being provided for taking rollers out of engagement with one another whilst maintaining the aforementioned engagements between the drive members.

2. An apparatus according to Claim 1 wherein the drive members are constituted by gears.

3. An apparatus according to Claims 1 or 2 wherein each of the forming means, sealing means and severing means comprises a respective pair of rotatable rollers which is driven by a respective set of four drive members.

4. An apparatus according to any preceding claim wherein the said rotatable rollers may be replaced when out of engagement with each other by rollers of a different size.

5. An apparatus substantially as herein described and as illustrated in any of the accompanying drawings.