FR2484387A1 - Container heat sealing through conveyor based machine - uses fixed coil HF induction heater with single rigid turn inducing currents in disc - Google Patents

Abstract

The machine handles containers e.g. bottles, canisters etc. in series, and includes closure and/or heat sealing of the containers. The machine has a high throughput rate and uses a high frequency induction sealing system that does not require its induction coil to be reset for each container. The machine is based on the use of two synchronised endless conveyer belts set one above the other (2, 3). The lower belt carries the containers (30), the upper carrying the container caps. This latter can be adjusted in height above the lower and presses the caps onto the container tops. Heat sealing is carried out at the beginning of the conveyer the remaining section allows the seals to cool. The induction coil consists of a single rigid turn (31) inducing currents in a metal disc (34) directly on the mouth of the container.

Description

 The present invention is in the field of container closure techniques, such as flasks, jars, or the like, and its subject is an induction heat-sealing process as well as preferred means for implementing said process and a closure machine and / or heat-sealing the containers.

 We know in particular from a French patent nO 1 461 000 a method and a device for applying sealing membranes on containers; according to this method and on condition that either the membrane comprises electrically conductive constituents, or that such electrically conductive constituents are constitutive of the parts of the receptacles adjacent to the membrane, an alternating magnetic field of high frequency induced in the metallic parts of the eddy currents which heat these parts and allow the fusion of a sealing material such as wax between the membrane or cover and the mouth of the container; such a method is implemented by means of a heat-sealing head shaped to surround and apply the seal on the mouth, the heat-sealing head comprising one or more electrically conductive turns preferably cooled by internal circulation and constituting an organ , said inductor, for producing the magnetic field. According to this process, the heat-sealing head moves at the same time as the container by means of an appropriate transfer machine of the so-called carousel type.

The aforementioned method and its means of implementation have undoubtedly constituted a considerable advance in the techniques of heat sealing, in comparison for example with previous methods in which the heat was communicated to the seal by conduction; however it is understandable that the supply of intense current at high, frequency and coolant poses delicate problems of protection and wear, since the member to which they are applied is movable relative to the frame of the machine transfer
It will also be noted that, to the knowledge of the applicant, the transfer machines proposed hitherto for capping containers, are of the kind with circular transfer, also called barrel or carousel 9 in the general case of purely mechanical capping operations being carried out during transfer, these machines are relatively simple in design and are fairly reliable; may however criticize them for a certain weakness in the rate, but their low cost makes it possible, by multiplying them, to overcome this drawback, it is different when, in addition to the plugging proper, the additional operation of heat sealing and in particular heat sealing is imposed on them. high frequency induction
A first object of the present invention is to propose a transfer machine making it possible to effect the plugging and / or the heat sealing of containers at a very high rate, independently of the heat sealing means used.

A second aim is to propose a high-frequency induction heat-sealing process, in which the production of the magnetic field is carried out at a fixed station, thereby eliminating the drawbacks of the mobility of the inductor.

 According to the present invention an automatic machine for capping and / or heat sealing a container by means of a cover and / or a capsule, is generally characterized in that the transfer of the containers is linear, or rectilinear , on at least the part of the machine where the plugging and / or heat-sealing operations are carried out, and mainly in that said machine comprises to cooperate a first so-called lower conveyor or even carrier on which the containers are placed, said conveyor carrier being rectilinear on at least part of its path, a second so-called upper conveyor or presser, said second conveyor being, on part of its path, rectilinear and substantially parallel to said rectilinear part of the first conveyor and being located above from it at a distance very slightly less than the height of the clogged containers, said second conveyor having an upwardly inclined entry section which slopes gently se-cond conveyor supporting equidistant sealing and / or heat-sealing members, and finally motor and transmission means for isoeinetically animating said first and second conveyors.

 It follows from these general provisions that it is possible, while respecting an imposed residence time of the containers on the machine, to increase the speed of transfer, therefore the rate, provided that the length is increased, which can be achieved at much lower cost and without significantly increasing the surface area compared to circular transfer machines.

 Such a machine comprises, as is known for circular machines, in the vicinity of its inlet section at least one screw, and preferably two superimposed, constituting an evenly distributed means of the containers on the carrier conveyor, said screw at least being animated in synchronism with said conveyors.

 Also preferably, the carrier conveyor being supported and guided by a frame of the machine, the pressure conveyor is supported and guided by a frame adjustable in height above the frame. It follows from this arrangement that the machine can accept containers of any height within reasonable limits and that the pressure exerted by the pressure conveyor can be finely adjusted.

 Preferably, finally, the aforementioned conveyors are "tap-is" made up of pallets articulated on each other in the manner of chain links and the closure and / or heat-sealing members mentioned above are detachably fixed on said pallets.

 Still according to the present invention, a method of heat-sealing an orpercule on an excipient, said method being of the high-frequency induction type according to which an alternating magnetic field induces, in electrically conductive parts of the lid and / or of the neck of the container, electric currents which cause, by the Joule effect, heating of said metal parts, said magnetic field being produced by a loop conductor called inductor, is mainly characterized in that said container is movable relative to the inductor, and in that an electrically conductive piece, known as a focusing relay, interposes between the inductor and said metal parts of the cover or of the container, said relay accompanying the container in its relative movement, said relay being intended to intercept a large flow from the inductor in order to restore in the vicinity of said metal parts a flow substantially equal to the intercepted flow.

 In the general case of implementation of the method and in order to achieve the desired goal, the inductor is fixed relative to a machine frame, itself fixed relative to the ground and consequently it is the containers which are movable by compared to the machine frame which is thus defined as a heat-sealing and possibly capping transfer machine. It will be noted that the method as defined above in its generality is applicable both to a circular transfer machine and to a linear transfer machine as described above and that it is entirely suitable for the latter type of machine. - transfer at high speed.

 According to what is said above and so that the duration of induction is sufficient, it is necessary that said inductor extends over a certain part, called heating zone, of the path of the containers; it is also necessary that the pressure valve is kept under pressure during its passage through the heating zone then consecutively during its passage through a so-called cooling zone; practically the length, on the path of the containers, of the cooling zene will be equal to at least three times the length of the heating zone.

 Still according to the present invention, the aforementioned focusing relay consists, in the generality of its design, of two electrically conductive loops forming a single circuit, the first so-called interception loop, delimiting a fairly large surface, being intended to intercept part of the flow of the inductor to generate an intense current in the circuit, the second so-called restitution loop, delimiting an area substantially identical to the section of the neck of the container, being intended to restore, under the effect of said current, a significant flow in the vicinity of said pass.

According to a preferred embodiment for the simplicity of its execution, for its energy efficiency and for its possibilities of use, said focusing relay is a metal crown, of copper for example, split on a radius to interrupt the continuity of the crown; thus the first loop is formed by the outer edge of a metal crown, or hollow circle in its center, the second loop is constituted by the inner edge of the crown, or of the central recess, the first and second loops being connected to form a single circuit by the edges of a cutout interrupting the continuity of the crown Preferably the edge of said central recess intended to be opposite
c of the stopper container, is shaped as a shoulder so as to be able to simultaneously press on the cover and surround the upper edge of the neck.

Preferably, the focusing relays are removably mounted on the capping machines by means of a support piece on which they are permanently fixed; this part, as well as the components of the machine which supports it, is made of non-conductive material
The present invention in its various aspects will be better understood and details will be apparent from the descriptions which will be given in connection with the figures of the appended plates in which
Fig.l is a schematic representation seen from above of a linear sealing and / or heat sealing machine according to the invention,
Fig. 2 is an elevation of the same,
Fig.3 is a more detailed illustration of an input section of a machine of the previous figures,
Fig.4 is a schematic illustration of the implementation of the method according to the invention,
Fig.5 is a plan view of an embodiment of a focusing relay and its support part, implemented in the method of the previous figure,
Fig. 6 is a section of the same,
Fig.7 is a partial schematic illustration in plan of the implementation of the process of Fig.4 by means of a linear transfer machine,
Fig. 8 is a partial schematic illustration in plan of the implementation of the method of FIG. 4 by means of a circular transfer machine, and
Fig.8bis is a section along AA of the previous figure.

 In Figs. 1 and 2, the sealing and / or heat-sealing of containers such as bottles 1 is carried out by means of a linear transfer machine which essentially consists of two endless conveyors 2 and 3 delimiting in height a transport corridor 4 or circulation of containers; the conveyor 2, said carrier1 is supported and guided by means of slides for example, by a frame 5 of the machine; this conveyor, according to this structure, is driven by pinions, drums, or other members such as 6.

 The conveyor 3, said presser, is supported by a chassis 7 adjustable in height above the chassis 5 the height adjustment is preferably obtained by moving the chassis 7 along the rails or vertical guide columns 8 and 9 to the means of vertical screws driven in rotation by a common shaft and bevel gear; this movement mechanism is not shown in the figures.

 It should be understood that the facing faces of the conveyors are guided, for example by sliding, so that they remain rigid and parallel.

 The pressure conveyor 3 has an entry section 10 inclined upwards in a gentle slope, so that the support of the conveyor on the containers is made progressively as they are introduced into the transfer corridor. 4 supported by conveyor 2.

 The machine comprises, like the machines of the prior art, supply means II and discharge means 12, such as a carpet. It comprises at its inlet section a couple of superimposed screws 13 constituting a means for equally distributing the containers on the carrying conveyor, however, and in accordance with the invention, advantage is taken of the firm holding of the containers in the thread of its screws to use the section d entry of the machine as a plug fitting station by means of a distributor shown diagrammatically at 14.

 The pressing conveyor 3, the carrying conveyor 2 and the evenly distributed screws 13 are driven synchronously, or even isokinetically, with respect to the movement that each prints in the containers, by means of a motor-variator group 18 and by means of means transmission diagrammed in 15 which can be chains as well as shafts, stressing however the positive nature of these transmissions.

 The transfer corridor 4 is divided into two sections: a section 16, called heating, close to the inlet section, and a section 17, called cooling.

When the machine of FIGS. 1 and 2 is used for heat sealing the respective lengths of sections 16 and 17 are such that they allow on the one hand the melting of the heat sealing material comprised between the cover and the edge of the container, and d on the other hand the resolidification of this material, these lengths also depend on the heating means used; if for example the heat is brought by conduction by means of a hot room, it will take more cooling time, therefore a greater length of the section 17 than if the rise in temperature results from the action of a field such as magnetic or electromagnetic (microwave). It seems, according to the experience of the Applicant, that the ratio of the lengths of sections 16 to 17 respectively, either at most equal to a third, or even that the length of the cooling section is at least equal to three times the length of the heating section.

 In FIG. 3, it appears more clearly, preferably, that the conveyor 3 is a belt made up of pallets such as 20 articulated to each other in the manner of chain links, a pair of notched wheels 21, called input , anchor in the articulation axes 22 the pallets and ensure a positive drive of the mat; there is a slide 23 on the lower edge of the chassis 7 made of a material such as Teflon with a low coefficient of friction; the slide 23 is intended to constitute a firm support for the pallets 20. The pallets 20 have a length equal to a fraction of the pitch of the screws 13 and some of them support a sealing and / or heat-sealing member, such as the organs 24.

 There is shown in the figures a spout 25 of the dispenser 14 of the previous figure; it appears that during their progression the necks of the receptacles extract from the spout 25 the capsules such as 26 which can incorporate the heat-sealable seal.

 We also note in fig.3 that the frame 7 may include a recess 27 intended to constitute a housing for heating means.

It also appears in FIG. 3 that the slope of the entry section of the presser conveyor is about fifteen degrees and that the connection of this entry section with the straight section is effected by a rounded 28 d 'large enough radius
Finally, it should be noted that the design of a machine as described above does not determine the choice of the type of closure, which can be as well a simple encapsulation, as a heat sealing by a seal, than the two, no more than it does not determine in the case where the heat sealing is used, the heating means used for this heat sealing; however, it will be noted that it is particularly suitable for the heat-sealing process which will be described with the aid of the following figures.

 In fig.4 and in order to illustrate the heat sealing pro csde of the invention, there is shown a container 30 circulating below an induction loop 31, the container 30, bottle in this case, is supported by a plate 32 while a plate 33 compresses by means of a split metal crown 34 a capsule 35 on the neck of the container.

 The loop 31 is constituted by a hollow tube of electrically conductive metal such as copper, the hollow tube is supplied with high frequency alternating current, for example two megahertz; the passage of current in the loop produces a magnetic field of identical frequency; this field at a given instant can be represented by the arrows 36, it will be noted that the technology of such induction loops, as well as their means of supply, is well known in itself.

 The method of the invention consists in circulating in the magnetic field produced by the loop the crown 34 bearing on the plug. The crown 34 has a configuration which will be described later and which allows it to act as a relay concentrating the magnetic flux picked up by its entire surface, in its central recess; the crown is for this reason called focusing relay. It appears that thanks to the use of this relay a sufficient magnetic flux can be supplied to the metal parts incorporated either in the cover 1 or in an overcap capsule, or in the neck of the bottle itself, while leaving the induction loop fixed, this last characteristic has two very appreciable consequences on the economy of the machine, firstly the design of this one is considerably simplified and secondly its working rates are considerably increased.

 On figO5 and 6 we note that as has already been said the focusing relay is a metal ring 34 split in 37 1 therefore the periphery 38 of the ring constitutes a conductive loop in which the variable magnetic flux induces a current; this current is all the stronger for a given field and frequency the larger the diameter of the crown. The induced current is transmitted in the loop 39 constituted by the edge of the central recess 40, by the edges of the slot 41 and 42; the periphery 38 of the crown constitutes an interception loop while the periphery 39 of the central recess constitutes a restitution loop.

As can be seen in fig.5 the edge of the recess 39 is shaped as a shoulder 41 to cap the capsule 35 and allow it to exert pressure while making the loop 39 as close as possible to the metal parts included under the capsule.

 Preferably split rings, such as 34, are permanently mounted on supports 43 which are themselves provided with adaptation means on the capping machine.

 The capping transfer machines allowing the implementation of the process described above will advantageously be of one of two types, with linear transfer or with circular transfer.

 In fig.7 which schematically illustrates part of the induction or heating zone, the machine is a linear transfer machine similar to that of FIGS. 1 to 3. The induction loop 50 has a median axis 51 along the following lines the straight path of the focusing relays such as 52; the focusing relays 52 are mounted on pallets 53 hinged to each other in the manner of chain links, as was said for the machine of FIGS. 1 to 3; in the machine of these figures the housing 27 formed in the chassis 7 can be used to house the inductor 50.

 In fig.8 analogously to what is shown in fig.7 the machine is a capping machine ge-circular transfer; it will mainly be noted that the median axis 55 of the induction loop 56 is curved to follow the circular path of the focusing relays 57; on this machine as on the previous one the inductor is fixed relative to the frame of the machine.

 In fig; 8bis there is shown in elevation and in section a plugging element mounted on a column 58 with vertical movement, the element comprising the relay 57 and a support 59 entering the heating zone below the inductor 56.

 Although embodiments of the present invention have been shown more or less schematically in order to illustrate it, it should be understood that the scope of the invention is not limited to these above-mentioned forms. described but that it means any machine or process for sealing and / or heat-sealing defined by the claims which follow.

Claims (2)

RESELL T CATI ON S 1.- Automatic capping and / or heat sealing machine  cipient.s by means of a seal and / or a capsule, character  laughed  in what she understands to cooperate  - a first conveyor (2) said to be lower or still carrying on  which containers are placed, said carrier conveyor  being rectilinear on at least part of its path,  - a second conveyor (3) called upper or even presser,  said second conveyor being, on a part (16,17) of its  path, straight and substantially parallel to said part  straight of the first conveyor and being located below:  him at a distance very slightly less than the height of  clogged containers, said second conveyor having a cross section  entry (10) inclined upwards gently sloping,  - motor and transmission means (15) for driving  isokinetic way said first and second conveyors 2.- Machine according to claim 1, characterized  in that it includes in its section of  at least two superimposed screws (13) constituting a means  evenly distributed containers on the carrying conveyor,  said screws being animated in synchronism with said cones  voyeurs;  3.- Machine according to claim 2, characterized  in that the carrying conveyor is sup  carried and guided by a frame (5) of the machine, the conveyor  presser is supported and guided by a frame (7) adjustable in  height above the frame 4.- Machine according to claim 10, characterized  - in that said conveyors are belts made up of  pallets articulated on each other in the manner of  chain links, and  - in that sealing and / or heat sealing members  are removably attached to said pallets 5. Machine according to claim 4, characterized  by an induction loop called "induc  high frequency electromagnetic field (31.50),  arranged above the first conveyor in an area (16)  called heating, said induction loop being fixed by  relative to the machine frame 6.- Machine according to claims 4 and 5, characterized  in that said plugging members  and / or heat sealing are constituted by foca relays  electromagnetic field readers, each focal relay  sator comprising two electrically conductive loops forming  a single circuit, the first so-called intercept loop  tion, delimiting a fairly large area, being intended  to intercept part of the inductor flow to generate  an intense current in the circuit, the second loop called  restitution, delimiting an area substantially identical to  the section of the neck 9u container, being intended to restore,  under the effect of said current a significant flow in the vicinity of the  said neck 7.- Machine according to claim 6, characterized  - in that said first loop is constituted by the edge  outside (38) of a metal crown (34), or circle,  hollowed out at its center,  - in that said second loop is constituted by the edge  inside (39) of the crown, or of the central recess, and  - in that the first and second loops are connected for constitute a single circuit by the edges (41,42)  a cutout (37) interrupting the continuity of the crown 8. Machine according to claim 7, characterized in that the edge of said central recess  is shaped as a shoulder (41) so that it can simultaneously  apply pressure to the cover and surround the upper edge of the container neck.