The invention relates to a device for pressing and seaming, comprising clamping jaws for attaching an end piece of a package to the package, wherein the press surfaces of the clamping jaws are facing a counterpart that surrounds the clamping jaws.

For filling packages with food, automatic package forming and filling lines are used, in which the package is formed of a blank, filled for example with liquid- like food, and sealed. For the manufacture of such packages, cardboard is normally used, in which at least one side has been treated with materials designed for the seaming, the gas and liquid tightness as well as printing of the package material. In the selection, forming and filling of such packages, particularly the requirements of cleanliness are taken into account; in other words, the package must also be tight at the seams, and the aim is to minimize the access of foreign substances and micro-organisms into the package in connection with the filling.

A package formed for example of a cardboard blank by seaming, partly still open, is filled in a filling unit, which is aseptic or fulfils the sufficient requirements of cleanliness, with for example liquid-like food which may be milk, juice or any other flowable food. The liquid-like food can also be viscous substance, and it refers to all liquid materials that can be packed by pouring. The packaged food can also be solid, especially composed of particles, such as in the form of pieces, powder, grains or flakes. After filling such a package, the aim is to seal it tightly as soon as possible. In the filling line, successive packages on a conveyor stop under a nozzle which dispenses a predetermined liquid volume or a mass of solid substance into each package.

For example, a fibre-based plastic-coated material, such as cardboard, is used as a packaging material. This kind of material is commonly called liquid package laminate. The seaming coating is to be selected so that it can be heat-sealed or sealed with some other method. In the case of a food product, the gas and liquid tightness of the packaging material is important, and in addition to the sealable layer, there can also be one or more layers acting as a particular barrier. The package, for which the device for seaming according to the invention is intended to, comprises a tubular shell part manufactured of, for example, a cardboard blank by wrapping and sealing the edges to each other, wherein the edges overlap partly and attach to each other by means of a sealing coating of the cardboard, for example a plastic coating, that is heated or otherwise energy treated to bring it to a sealing state. Of this shell part a closed package is made by attaching end pieces, whose outline corresponds to the cross-section of the shell, to both ends of the shell, which end pieces have been separated from the cardboard material for example by die cutting. The end pieces are sealed to the cylindrical part by pressing and exerting energy on the coating, which brings it into a sealing state. The material of the liquid package can also be other than a cardboard-based material.

In seaming the end piece, it is particularly important to acquire a uniform pressure on the circumference of the whole package, because otherwise weak spots, which degrade the preservability of the package, might remain in the joint. The mobile clamping jaws of the seaming device press the flange of the end piece from the middle towards the inside surface of the shell part and the counterpart outside the shell part. There are several mobile clamping jaws sector by sector on the periphery of the end piece, wherein areas remain between them where the pressing effect is weaker. In order to reach a uniform thickness of the seam along the whole periphery of the end piece, two consecutive seaming devices are used in such a manner that the clamping jaws of the latter seaming device are in a different angular position and their centre hits the areas where the boundaries of the mobile clamping jaws of previous seaming device have located.

Particularly with two successive seaming devices, an overall compression is achieved on the whole periphery of the end piece. However, this arrangement does not take into account the effect of a single clamping jaw on the seaming result. Due to the position of the clamping jaw or the external counterpart, the compression may, in fact, become slightly one-sided, which may result in slight variation of the pressure along the periphery. It is an aim of the invention to eliminate the above-mentioned drawbacks and to present a device, by means of which an even more uniform pressing result is obtained than before on the whole periphery of the end piece, and variation of the clamping pressure in small scale is avoided. To achieve this aim, the device for pressing and seaming according to the invention is primarily characterized in that the clamping jaws are arranged rotatable in the plane of the periphery formed by the press surfaces. Thanks to this, the press surface will automatically assume the correct position with respect to the facing annular counterpart. In this way, a uniform pressing force is obtained on the whole area of the press surface of the jaw. In practice, the clamping jaws can be arranged rotatable on axes connected to a mechanism that produces the pressing movement, such as a lever mechanism or a linear motion mechanism. The rotation motion of the clamping jaw may be limited; in other words, it has certain extreme positions. The device for pressing and seaming also comprises means for direction seaming energy to the joint between the end piece and the shell part during pressing, and these means can be provided in the mobile clamping jaws.

As material for the shell part and the end piece, it is possible to use a liquid package laminate, which has suitable properties for the packaged liquid food and is cardboard or packaging material based on some other material, which comprises the layer of the seaming material at least on the surface to be fixed by seaming. The liquid package laminate may also comprise one or several plastic layers acting as barriers or a single aluminium layer acting as a barrier.

In the following, the invention will be described in more detail with reference to the appended drawings, in which

Fig. 1 shows schematically the phase preceding the seaming device, wherein liquid is packaged in cycles,

Fig. 2 shows a vertical cross-section of a detail of the seaming device,

Fig. 3 shows the seaming device from below, and Fig. 4 illustrates a possible mechanism for the clamping jaws of the seaming device.

In Fig. 1 , the operation of the filling device preceding the seaming device in the filling line is shown to illustrate the use of the invention. The filling device comprises a product container 1 , into which liquid food or solid food (as particles such as pieces, powder, grains or flakes) is supplied by a feeding channel 2. In the figure, a feeding channel 2 is introduced in the lower part of the container 1 from the side near the bottom of the container (solid lines), but it can also be introduced from below to the bottom of the container, or from above to the container (broken lines). From the bottom of the product container, a filling channel 3 extends downwards, its lower end being provided with a filling valve 4 to open and close the filling channel for filling bypassing liquid packages P, transferred on a conveyor, with a predetermined liquid volume or mass of solid material. From the product container, the liquid or solid material flows into the channel 3 and into the package P by gravity or additionally by the effect of pressure in the container. After the filling phase, the packages are moved to the closing phase, which is illustrated with an arrow S in Fig. 1.

^' The liquid packages are normally made of a liquid packaging laminate by seaming. The packages can be different in shape, their shell parts having been made, for example, of cardboard blanks by wrapping and seaming the edges together. The package is sealed by attaching end pieces separated from cardboard material for example by die cutting to both ends of the shell part, which pieces are seamed to the shell part. The shell part can be cylindrical, but the cross-section of the package can be other than round, and it is characteristic for all these kinds of packages to have a tube-like shell part formed of a blank by wrapping and closed at both ends. According to one alternative, steps are taken so that the end piece forming the lid in the finished package, where there is a drinking aperture sealed with a suitable manner, is seamed to the end of the shell part already in the package forming unit, and the container-like package, whose other end is still open, is transferred to the filling and sealing unit, where it moves in an upright position with the open end facing upwards first under the filling device in Fig. 1 and then under the sealing device on a conveyor that transfers the packages successively to the filling phase and sealing phase step by step. In the sealing phase S, an end piece forming the bottom of the package is placed at the open end, which piece is sealed to the upper edge of the above-mentioned shell part. Principles for forming and sealing the package have been dis- closed e.g. in the prior patent publication EP 1 091 874 B1. However, it is possible that the end piece to be placed in the package after the filling phase S is the lid of the finished package, and the end piece forming the bottom of the package has been installed previously in the package forming unit.

The function of the seaming device of the sealing device is shown as a vertical view in the height direction of the package in Fig. 2. The end piece E sealing the end of the package P, which is also, for example, of a coated, fiber-based material such as cardboard, is inserted with a gripper known as such from the top inside the shell part of the package P to a suitable distance from the upper surface of the liquid so that the edge flange E1 turned upwards of the end piece E stays against the inner wall of the shell part. There is material that is sealable by means of heat or other energy brought from the outside, such as heat-sealable plastic, on the lower surface of the end piece E and in the inner wall of the shell part.

When the end piece is in its place, the package P is lifted up to the seaming device 5 having clamping jaws 6 that clamp the edge flange E1 and the upper edge of the shell part between the mobile jaws and the fixed counterpart 7 of the seaming device. The fixed counterpart 7 of the seaming device acts, in a way, as a counterpart for the pressing and surrounds in an annular manner the upper edge of the shell part from the outside, and radially outwards mobile jaws 6 which are several in number and situated in different sectors, with their press surfaces 6a corresponding to the shape of the edge flange of the end piece, press the edge flange from the centre against the upper edge of the shell part and the fixed counterpart 7. If the of cross-section of the shell part and the end piece are circular or different in shape, the mobile jaws 6 are segments shaped like an arc or having the outline of the different shape. The mobile jaws 6 can be heated or they can have means which exert energy on the facing coating materials and cause the seaming of these to each other. The mobile clamping jaws 6 and the fixed counterpart 7 (counterpiece) are above the conveyor that moves filled packages P step by step. When the package P has moved under the seaming device, it is lifted by an actuator up to the seaming device in such a manner that the edge flange E1 of the end piece and the upper edge of the shell part enter the annular or differently shaped space between the clamping jaws 6 and the fixed counterpart 7.

In the fixed counterpart 7, there may be a zone 7a of elastic material at the location of the press surface 6a of the mobile clamping jaw in the height direction, which zone surrounds the upper edge of the shell part of the pack- age in an annular manner at the height of the seaming location. The clamping pressure caused by the press surface 6a is effective precisely on this zone 7a. This kind of a solution, by means of which it is possible to level out the uneven compression caused by an extra layer thickness in the vertical seam of the shell part, is described in more detail in the applicant's prior pat- ent application "A device for seaming a package". However, it is also possible to use a counterpart with a conventional hard counter surface, without altering the character of the invention.

Figure 3 shows the seaming device from below, this view illustrating the invention in the best way. The press surfaces 6a of the clamping jaws 6 placed inside the edge flange E1 of the end piece E are facing the annular solid counterpart 7. The shape of the press surfaces 6a conforms to the shape of the counterpart 7 as closely as possible so that in the pressing position a clearance whose width is as uniform as possible is left between the press surfaces 6a and the facing surface of the counterpart 7, in which clearance the end piece and the shell part are compressed together under a uniform pressure. In the pressing position, the press surfaces 6a follow the periphery that is a concentric circle with the counter surface of the counterpart 7 in the figure. Peripheries with other shapes are possible as well, depending on the shape of the horizontal section of the shell part of the package to be seamed.

The clamping jaws 6 are arranged rotatable in the plane of the periphery formed by the press surfaces (arrows). By this, it is possible to eliminate irregularities of the pressure due to a possible malposition of the clamping jaws at a single clamping jaw. The optimal function is obtained when the rotation axis A is on the axis of symmetry of the clamping jaw, which axis of symmetry coincides with the clamping direction and divides the clamping jaw in two mirror-symmetrical parts.

In practice, the clamping jaws 6 are arranged rotatable on axes A which are connected to a mechanism that moves the clamping jaws 6 to and from the clamping position and that may include a lever to produce a reciprocal pivoting movement but that may also produce a linear movement towards and away from the counterpart 7. In the joint between the clamping jaw and the axis A, a limiter may be provided for the rotation movement, to limit the rotation to a given angle on both sides of the mid-position. The rotation may only comprise a few degrees, because no great deviations occur in practice. Figure 4 shows an example of the pivoting mechanism of the clamping jaw 6. A lever 8, in whose lower end the rotation axis A for the clamping jaw is provided, is arranged in the frame of the seaming device pivotable around a horizontal axis B that is perpendicular to the axis A. Above the axis B, the lever comprises a diagonal guide groove 8a, which receives a transmission pin 9 performing a reciprocal linear movement deviating from the direction of the groove and, in effect, transmitting the movement to the lever 8 and thereby to the clamping jaw 6. The transmission pin 9 is fixed to an actuator that moves, simultaneously with the pin, other pins which are connected in the same way to corresponding levers 8 and clamping jaws 6. In this way, with a single linear movement of the actuator (the pins 9 up), the clamping jaws 6 can be turned to the clamping position, closer to the counterpart 7, which position is illustrated in Figure 4; and with an opposite linear movement (the pins 9 down), the clamping jaws can be turned to the open position, farther away from the counterpart 7. The actuator may be, for example, a pneumatic cylinder. The pivoting axis B, the press surface 6a and the guide groove 8a are placed in such a way with respect to the counterpart 7 that when moving to the clamping position at the end of the pivoting movement, the press surfaces 6a and the facing surface of the counterpart 7 lie approximately parallelly to each other. Figure 4 further shows a limiter 10 for the pivoting movement, for adjusting the clearance left between the press surface 6a and the counterpart 7 in the clamping position. The limiter 10 is an adjustment screw fixed to the frame of the seaming device and directed towards the front surface of the lever, which hits the free end of the adjustment screw at the end of the pivoting movement.

To make the seaming evenly strong over the whole periphery of the shell part, the package P is transferred, maintaining its position, by the conveyor to another seaming device where the mobile jaws 6 are in a different angular position in relation to the previous seaming device. Now, the jaws 6 and the fixed counterpart 7 compress and seam the edge flange and the shell part in locations left between the ranges of action of the jaws 6 of the previous seaming device and where the joint may be weaker. This latter seaming device also has the structure described above.

When the edge flange E1 and the upper edge of the shell part have been sealed together, a short section of the upper edge of the shell part left above the upper end of the edge flange is turned over the edge part. This can be performed in a particular finishing seaming unit, the purpose of which is primarily to provide the closed package with a neat, finished appearance.

Figure 3 shows a seaming device with three evenly spaced clamping jaws 6 which are identical in shape, to make the pressure evenly distributed over the whole periphery, but the structure is not yet too complex. The number of the clamping jaws 6 may also be different.

The invention is not restricted to the embodiments described above, but it can be modified within the scope of the inventive idea presented in the claims. As mentioned above, the invention is not depended on the position of the sealed end piece in the final liquid package sold to the consumer. Moreover, the invention is not limited to seaming devices applied on a filling line, but it may also be applied in seaming devices which, in a package forming unit, seal the first end piece to the shell part on the same principle, to manufacture a package which will enter the filling line. Thus, the device for pressing and seaming is either the seaming device for a package filled with a food product or a seaming device for a package not yet filled.