Thermoforming method for film on blister packing machines and apparatus for it

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a thermoforming method for film on blister packing machines and apparatus for it, more specifically a thermoforming method for film on blister packing machines and apparatus for it, realized in such a way as to be capable of preventing warping of blister sheet, when performing blister packaging by using a polypropylene film which is disposable by burning, and forming a film with a largest possible thickness at the portion forming depressions (hereinafter referred to as “pockets”).

[0002] Conventionally, in blister packaging for packaging tablets such as chemicals, etc. by using film such as PVC film, etc., the normal practice consists in heating a long film fed intermittently and continually as desired by pinching it between flat-shaped hot plates disposed face to face and movable in approaching and separating directions, forming, in this heated and softened film, pockets in which to house one or several pieces of tablet each by means of a forming die, and then feeding tablets into the respective pockets, sealing the pockets by placing aluminium foil along the film having such pockets, and cutting the film so that the required number of pockets may be contained in one piece of sheet, as products.

[0003] By the way, the forming of film on said conventional blister packaging machine is generally made by unwinding film continuously or intermittently from a roll which took up PVC film in the shape of a tape, heating the entire face of the film to a temperature suitable for forming pockets, by means of a heating unit, disposed in such a way as to face the both faces of this film in linkage with said unwinding and move in approaching and separating directions against the film, and then feeding the film to the forming system, forming part of the film into pockets of required shape from the forming die on one side and, after filling tablets in these pockets, sealing the pockets by attaching aluminium foil to them.

[0004] For that reason, there was a problem that, while PVC film is suitable for forming part of heated film into pockets of required shape, the film thickness of the formed pockets, especially at the top face portion of the pockets, becomes extremely smaller compared with other parts, because the pockets are formed by heating the entire face of the PVC film, and the pockets are easily deformed at the time of packaging of tablets, after filling them in the pockets, made by placing 2 sheets one upon another with their pockets facing each other and in opposite directions, or in the course of distribution or sale.

[0005] Moreover, when the PVC film in which are formed pockets is cut into sheets as blister sheets, the surrounding portion left after cutting in the shape of sheet becomes scraps. The products and the scraps are taken out separately, and only the scraps are disposed of. However, the scraps, which produce high temperature with burning and may damage the incinerator, are disposed of by filling in, etc. in recent years, involving high scrap treating costs. To avoid this problem, the blister sheet has come to be formed by using polypropylene which can be burned in an ordinary refuse incinerator.

[0006] This polypropylene film sheet, like PVC film sheet, has a problem of becoming extremely thin at the formed pockets, especially at the position of the sheet forming the top face portion of the pockets, compared with other portions, making the pockets easily deformable after filling of tablets. Another problem is that, when the film is heated on the entire face for the forming, the blister sheet after filling of tablets is warped because of a difference in coefficient of heat contraction between the polypropylene film sheet and the aluminium foil, and this makes it impossible, when performing packaging of tablets by placing sheets one upon another with their pockets facing each other, to place them one upon another automatically with a machine, requiring execution of this operation by hand work and thus leading to poor working efficiency.

SUMMARY OF THE INVENTION

[0007] The objective of the present invention, realized in view of the problems produced when forming pockets by heating the film of said conventional blister packaging machine, is to provide a thermoforming method for film on blister packing machines and apparatus for it, realized in such a way as to form pockets with no extreme reduction in the thickness of the sheet at the top face portion of the pockets, and to enable the placing of sheets one upon another without warping.

[0008] To achieve said objective, the thermoforming method for film on blister packaging machines according to the present invention is characterized in that it consists of the pinching of a film, fed intermittently in synchronization with the open/close drive of the die on a thermoforming system, between the dies of the thermoforming system, heating only the pocket forming portion of the film locally by pressing it in contact with the surface of hot plugs disposed facing the pocket holes of the forming die, by injecting compressed air from the forming die side, and then stopping the injection of compressed air from the forming die side, and injecting compressed air from the heating die side, and extending the heated portion of said film along the inner circumferential face of the pocket holes of the forming die to form pockets.

[0009] This thermoforming method for film on blister packaging machines, realized in such a way as to heat only the pocket forming portion of the film locally and extend the heated portion of the film along the inner circumferential face of the pocket holes of the forming die to form pockets, is capable of forming blister sheets without warping, even when using polypropylene film, which is liable to be easily deformed due to thermal contraction because the portions not forming pockets are not heated, and also capable of performing lap packaging of blister sheets by using an automatic machine and forming pockets without reducing the thickness of the sheet at the top face of the pockets, thus preventing deformation at the top face of the pockets after the filling of tablets.

[0010] In this case, it may be so arranged that the plugs retreat when the heated portion of the film is extended along the inner circumferential face of the pocket holes of the forming die.

[0011] This makes it possible for the heated and softened film to separate accurately from the plugs of the heating die, and the compressed air injected in this state acts uniformly on the film face, to accurately extend the heated portion of the film along the inner circumferential face of the pocket holes of the forming die and accurately form pockets.

[0012] Moreover, to achieve the same objective, the thermoforming system of film for blister packaging machines according to the present invention is a thermoforming system for film on blister packaging machines, realized in such a way as to pinch and heat the film, fed intermittently in synchronization with the open/close drive of the die on a thermoforming system, between the dies of the thermoforming system, and partially extend said heated film along the inner circumferential face of the pocket holes of the forming die to form pockets, characterized in that the dies of the thermoforming system are constructed with a forming die provided with pocket holes, a heating die provided with plugs to locally heat only the pocket forming portion of the film disposed facing the pocket holes of the forming die, and injecting mechanisms of compressed air disposed on the forming die side and the heating die side, respectively.

[0013] This thermoforming system for film on blister packaging machines, in which injecting mechanisms of compressed air on the forming die side and the heating die side are disposed respectively, is capable of heating only the pocket forming portion of the film locally and forming pockets by extending the heated portion of the film along the inner circumferential face of the pocket holes of the forming die, and can therefore form blister sheets without warping, even when using polypropylene film which is liable to be easily deformed by thermal contraction, because the portions not formed into pockets are not heated, and can also perform lap packaging of blister sheets by using an automatic machine and form pockets without thickness reduction of the sheet at the top face of the pockets, thus preventing deformation at the top face of the pockets after the filling of tablets.

[0014] The thermoforming system is constructed with a heating die and a forming die, so that they may make open/close operation in synchronization with intermittent feeding of the film, and it is so arranged that the heated film is pressed by compressed air pressure in such a way as to lie along the pocket holes, enabling the easy and accurate formation of pockets.

[0015] In this case, a compressed air injection hole may be formed at the inner bottom of the pocket holes of the forming die.

[0016] This makes it possible to heat the film by uniformly pressing it in contact with the plugs provided on the heating die from the forming die side, and form pockets of good accuracy in a beautiful shape.

[0017] Furthermore, it may be so arranged as to inject compressed air through the plug insertion holes in the heating die, and construct the heating die in the form of a water cooled jacket.

[0018] This makes it possible to clearly distinguish between the heated and non-heated portions of the film and form blister sheets without warping, because the non-heated portion is cooled even if the heated portion is heated to such an extent as to cause softening of the film.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]
FIG. 1 is an explanatory drawing showing the process of thermoforming method for film on blister packaging machines according to the present invention, (A) being a sectional view showing the state in which a film is fed between the dies of the thermoforming system, (B) a sectional view showing the state in which the film is pressed to the heating side with compressed air from the forming die side, and (C) a sectional view showing the state in which the film is press formed by compressed air to the forming side, respectively.

[0020]
FIG. 2 is a front elevation of the thermoforming system for film on blister packaging machines according to the present invention.

[0021]
FIG. 3 is a side view for above.

[0022]
FIG. 4 indicates a heating device, (A) being a front elevation, (B) a side view, and (C) a sectional view.

[0023]
FIG. 5 is a section view of the heating device indicated in FIG. 4.

[0024]
FIG. 6 indicates the plug base of the heating device, (A) being a front elevation, and (B) a partially broken side view.

[0025]
FIG. 7 indicates a forming die, (A) being a front elevation, (B) a side view, and (C) a sectional view.

[0026]
FIG. 8 is a front elevation of a blister packaging machine to which is applied the thermoforming method of film according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0027] The thermoforming method for film on blister packaging machines according to the present invention and an embodiment of the apparatus for it will be explained hereafter based on drawings.

[0028]
FIG. 1 shows the process of thermoforming method for film on blister packaging machines according to the present invention, while FIG. 2 to FIG. 8 indicate an embodiment of the thermoforming system on blister packaging machine according to the present invention.

[0029] The blister packaging machine according to the present invention is constructed in such a way that, as shown in FIG. 8, the polypropylene film F fed sequentially from the roll film R1 containing the film F is delivered by the feed roller 2 through the film connecting stand 1 and, after adjustment of tension, etc. by the fixed tension roll 3, fed intermittently by the guide roller 4 to the subsequent thermoforming system 5 and, after forming required pockets there, sent from the forming feed roller 6 to the film guide rail 7, and after tablets are fed into the respective pockets from a tablet feed system (not illustrated) on this film guide rail 7, sealed with the aluminium foil A1 which is supplied sequentially from the aluminium foil roll R2 containing the aluminium foil and seal rolls 8, 9 and, passing through the dancer roll 10, the slitter 11 and the guide roller 12, marked with the marking device 13, punched with the punching die set 14 and, after separation between the products in the form of sheet and scraps there, the products in the form of sheet are taken out through the discharge chute 15.

[0030] This thermoforming system 5 is constructed by providing a forming die 5A and a heating die 5B face to face and movable in the approaching and separating directions, as shown in FIG. 2, to pass said continuous sheet-like film F through the space between these forming die 5A and heating die 5B, synchronizing intermittent feed of this film F with the approaching and separating motions of the forming die 5A and heating die 5B.

[0031] It is so arranged that the continuous sheet-like film F moves upward about vertically from below through the space between these forming die 5A and heating die 5B facing each other.

[0032] The forming die 5A is constructed, as shown in FIG. 2 and FIG. 7, by installing forming die body 50 on a mounting base 51 provided movable in the approaching and separating directions, against the heating die 5B facing it. The forming die body 50 is constructed by forming, on its surface, a plurality of depressed pocket holes 52 in lines, to form a plurality of sheets forming 10˜12 pockets at a time, or 8 sheets as in the illustrated embodiment, though not particularly restricted to this number, so that a plurality of tablets, or 10˜12 tablets, for example, though not particularly restricted to this number, and forming compressed air supply routes 53 so as to supply pressure controlled compressed air into the respective pocket holes 52 through compressed air injection holes 53a.

[0033] The shape of these pocket holes 52 is not particularly restricted to the illustrated shape, but the compressed air supply routes 53, realized in a way to communicate with the respective pocket holes 52 through compressed air injection holes 53a, are connected to a compressed air source (not illustrated), so that compressed air may be fed synchronously into a plurality of pocket holes 52.

[0034] Moreover, the heating die 5B on the other side faces the forming die 5A, as shown in FIG. 2 to FIG. 6, and is usually fixed, but it may also be made movable in the approaching and separating directions, against the forming die 5A facing it.

[0035] Furthermore, the forming die 5A and the heating die 5B facing each other, which are fixed in vertical direction while being movable in the approaching and separating directions, may be made movable also in vertical direction in synchronization with intermittent feed of the film, to improve productivity by accelerating the feed speed of the film to be heated.

[0036] The heating die 5B is constructed by fixing a heating die body 55 to a mounting base 54 through a mounting tool such as bolts, etc., mounting, on this heating die body 55, a heater base 56 and a plug mounting board 57, and providing, on this plug mounting board 57, a plurality of plugs 58 in projection in such a way as to face the pocket holes 52 formed on said forming die 5A.

[0037] The heating die body 55 is realized, as shown in FIG. 4 and FIG. 5, by forming, on the back face side (55a) of the heating die body 55, a depression 55b hollowed in the heating die body 55, forming, on the back face side 55a, a plurality of plug insertion holes 55c in such a way as to face the pocket holes 52 formed on the forming die 5A, forming, at one end side, a cooling water feed port 55f and a drain port 55g, and also forming, in the heating die body 55 in such a way as to connect between this cooling water feed port 55f and the drain port 55g, a water channel 55e in the shape of a tunnel, though not particularly restricted to this shape, so that the supplied cooling water may circulate through the heating die body 55 to cool the entire part of the heating die body 55.

[0038] On the outer circumferential face on the back face side is formed a ring-shaped groove 55d, to ensure accurate installation on the mounting base.

[0039] The plug mounting board 57, which is a thick plate to be inserted in the depression 55b of the heating die body 55, is constructed by forming, as shown in FIG. 6, mounting holes 57c, to thereby be fixed to the heating die body 55 by means of bolts or screws, forming, on the plug mounting board 57, plug mounting holes 57a at the same position as that of the plurality of plug insertion holes 55c in such a way as to face the pocket holes 52 formed on the forming die 5A, and also forming a plurality of heater insertion holes 57b inside passing in either transversal or vertical directions.

[0040] And, a pipe-shaped heater is inserted in the heater insertion holes 57b, and plugs 58 are fixed to the plug mounting hole 57a by screwing, etc., so that a plurality of plugs 58 may be installed in projection in lines on the surface of the plug mounting board 57.

[0041] It is so arranged that, when the plug mounting board 57 on which are planted the plugs 58 as described above is inserted in the depression 55b of the heating die body 55, the respective plugs 58 are inserted in the plug insertion holes 55c. In that case, the tip face of the plugs 58 becomes about flush with the surface of the heating die body 55, and a clearance is formed between the outer circumferential face of the plugs 58 and the inner circumferential face of the plug insertion holes 55c, so that the compressed air for forming may be injected through this gap into the pocket holes 52 of the forming die 5A.

[0042] Next, explanation will be given on the method of forming pockets in a film by using the thermoforming system of film for blister packaging machine.

[0043] The film F wound in roll film R1 is delivered from the roll film R1 through a film connecting base 1, sequentially and intermittently, by a delivery roller 2, in synchronization with the open/close drive of the thermoforming system 5. At that time, the tension of the film is adjusted by a constant-tension roll 3 and, as a preset length of film is introduced, through a guide roller 4, between the forming die 5A and the heating die 5B of the thermoforming system 5 facing each other in such a way as to separate, the delivery stops, and the separated forming die 5A and heating die 5B are closed.

[0044] At that time, the film F is pinched at the outer circumference between the separated forming die 5A and the heating die 5B. However, since the clearance between the separated forming die 5A and the heating die 5B is set larger than the thickness of film, as shown in FIG. 1, the film F can move freely over a certain small distance in the direction of thickness, between the forming die 5A and the heating die 5B. If the forming die 5A and the heating die 5B are closed, the compressed air supplied from the compressed air supply routes 53 on the forming die 5A side is injected from the respective pocket holes 52, through the compressed air injection holes 53a, to press the film F against the forming face of the heating die 5B on the opposite side. Since the respective plugs 58 planted through the plug mounting board 57 are heated by the heater disposed on the heating die 5B, the film F pressed by the compressed air is pressed against the tip face of those plugs 58 and heated.

[0045] At that time, the heating die body 55 at the outer circumference of the plug insertion holes 55c in which are inserted the respective plugs 58 has a structure in the form of water cooled jacket inside where cooling water is supplied, the film pressed against the heating die 5B face at the outer circumference of the plug insertion holes 55c is not heated. In this way the film F is locally heated to the prescribed temperature.

[0046] Next, the supply of compressed air from the compressed air supply routes 53 on the forming die 5A side is stopped, and compressed air is injected from the clearances formed between the outer circumferential face of the plugs 58 and the inner circumferential face of the plug insertion holes 55c. As a result, the locally heated film F is pressed toward the forming die 5A side from the heating die 5B side.

[0047] At that time, the locally heated and softened film F is extended, only at the heated portion, along the inner circumferential face of the pocket holes 52 of the forming die 5A, to form pockets. Especially, because the tip face diameter of the plugs 58 is set to be slightly larger, by approximately 1 mm or so, though not particularly restricted to this value, than the diameter at outer circumference of the pocket holes 52, the film F2 at the outer circumference of this pocket hole 52 is extended more strongly than that of the film F1 at the inner bottom part of the pocket hole 52, and the extension of the heated and softened film F becomes thicker at the inner bottom part of the pocket hole 52 than at the inner circumferential face of the pocket hole 52.

[0048] This makes it possible to prevent deformation of the inner bottom part of the pocket hole 52 even with filling of tablets in the pocket holes 52.

[0049] After the pockets are formed in the film F between the forming die 5A and the heating die 5B, the two dies are separated from each other, and the next film is supplied intermittently, the pocket forming portion of the film separates from the forming die 5A, and the next film to be formed is introduced.

[0050] In that case, to make the extension of the heated and softened film F thinner accurately and easily at the inner circumferential face of the pocket hole 52 than at the inner bottom part of the pocket hole 52, the plug mounting board 57 may be made to retreat when compressed air is injected through the gap of the plug insertion holes 55c, to make the tip face of the respective plugs 58 to separate from the film face, though not particularly restricted to this construction.

[0051] As described above, by heating the film locally only at the pocket forming portion and cooling the surrounding face, it becomes possible to prevent production of warping due to heating in the film, because no unnecessary heating is made to the film as a whole, and to put products after filling of tablets and cutting into sheets, mechanically one upon another.

[0052] Explanation has so far been given on the thermoforming method for film on blister packaging machines and apparatus for it according to the present invention, based on an embodiment thereof, but the present invention is not restricted to the construction described in said embodiment and its construction may be changed as required to the extent not deviating from its purpose.

[0053] According to the thermoforming method for film on blister packaging machines of the present invention, realized in such a way that, after the film is locally heated only at the pocket forming portion, compressed air is injected from the heating die side, to make the heated portion of the film extend along the inner circumferential face of the pocket holes in the forming die to form pockets, no heating is made to the portion not forming pockets, making it possible to form blister sheet without warping even with the use of polypropylene film which is liable to be easily deformed with thermal contraction, perform lap packaging of blister sheet by using an automatic machine, and form pockets without reduction of thickness of the sheet at the top face of the pockets, thus enabling to prevent deformation at the top face of the pockets after filling of tablets and perform blister packaging of high quality.

[0054] Moreover, by making the plugs retreat, when extending the heated portion of the film along the inner circumferential face of the pocket holes in the forming die, it makes possible for the heated and softened film to separate accurately from the plugs, and the compressed air injected in this state acts uniformly on the film face, thus enabling to extend the heated portion of the film accurately along the inner circumferential face of the pocket holes in the forming die, and accurately perform formation of pockets.

[0055] According to the thermoforming method for film on blister packaging machines of the present invention, realized by disposing a compressed air injection mechanism on the forming die side and the heating die side respectively, and in such a way that the film can be locally heated only at the pocket forming portion, by means of plugs provided in the heating die, and that the heated portion of the film is extended along the inner circumferential face of the pocket holes in the forming die to form pockets, no heating is made to the portion not forming pockets, making it possible to form blister sheet without warping even with the use of polypropylene film which is liable to be easily deformed with thermal contraction, perform lap packaging of blister sheet by using an automatic machine, and form pockets without reduction of thickness of the sheet at the top face of the pockets, thus enabling to prevent deformation at the top face of the pockets after filling of tablets and perform blister packaging of high quality.

[0056] Furthermore, by forming a compressed air injection hole at the inner bottom of the pocket holes of the forming die, it becomes possible to heat the film by uniformly pressing it in contact with the plug provided on the heating die from the forming die side, and form pockets of good accuracy in beautiful shape.

[0057] Still more, by injecting compressed air through the plug insertion holes in the heating die, and constructing the heating die in a structure in the form of water cooled jacket, it becomes possible to clearly distinguish between heated portion and non heated portion of the film and form blister sheet without warping, because the non heated portion is cooled even if the heated portion is heated to such an extent as to cause softening of the film.

Thermoforming method for film on blister packing machines and apparatus for it

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CPC

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Priority Claims (1)