Patent Description:
Methods and systems for sealing various kinds of sealing materials have been known for several years.

There are different concepts of how a sealing material, like a plastic foil, can be wrapped around a product. One of those approaches is to use a sheetlike material and wrap it around a product so that the sheetlike sealing material is closed about the product forming a fin by the edges of the sealing material.

This fin can then be sealed by pressing together the edges of the sealing material forming the fin and at the same time applying heat so that the material locally melts and comes a sealing.

Further sealing steps may be performed by for example applying a "cross sealing" that also seals edges of the sealing material that run approximately perpendicular to the transport direction of the sealing material with the product therein.

Depending on the characteristics of the sealing material, the tension applied to the sealing material by the heating rollers of the sealing machine and the tracking rollers of the sealing machine that contact the sealing material in the region of the fin of the sealing material has impact on the quality of the sealing.

From <CIT>, A packaging machine comprising feed means and tube forming means for a heat-welding plastic film strip is known. First welding means weld between them the side edges of the strip while a feed line inputs into the tube thus formed products to be packaged. Second weld means weld transversely the tube at intervals to isolate each product in a section of said tube, thus realizing the package. Characteristically the first and second welding means are pressed against the strip parts to be welded by actuator means controlled by a control device to exert a pressure which is a function of the speed of travel of the strip.

Further, <CIT> describes a temperature measurement and control apparatus and a packaging film loading apparatus for use in a horizontal packaging machine. The packaging machine includes a pair of counter-rotating sealing and crimping head assemblies, each of which includes a plurality of sealing and crimping heads, respectively, which are rotated past a first infrared sensor assembly or a second infrared sensor assembly, respectively, for measuring the temperature thereof. Each sealing and crimping head includes a generally arcuate sensing arc mounted at the first end thereof, the sensing arcs being rotated past either an upper infrared sensor or a lower infrared sensor. The temperature measured by the infrared sensors is passed to a computer where a temperature control program is executed, whereupon the computer signals the individual electrical heating elements of the upper sealing and crimping head assembly, and the electrical heating elements of lower sealing and crimping head assembly to control the temperature of each individual sealing and crimping head therein. A packaging film loading apparatus is also described, which includes a film spool rotatably mounted at one of its ends on a film spool support arm, and a double action cylinder for moving the film spool support arm from a lowered loading position to a raised working position with respect to the packaging machine.

From <CIT>, a heat sealing device, in particular a heat sealing roller, in particular for tubular bag machines, with at least one sealing unit for creating a sealed seam and with at least one heating unit for heating the sealing unit is known. The heating unit comprises at least one heating element which is intended to be at least essentially homogeneous, in particular free of thermal discontinuities to transfer thermal energy to the sealing unit along a complete maximum circumference, in particular a complete maximum inner circumference of the sealing unit.

Further, <CIT> discusses a packaging machine that is adapted to form a web of packaging material into a tube to surround items to be packed, the tube then being sealed and severed between successive items to produce individual packages. The tube is formed by sealing one surface of an edge zone of the web to the same surface of the opposite edge zone of the web so that, in the finished package, the sealed zones form a flap extending longitudinally of the package. The machine comprises a machine bed and successive pairs of rollers located in the machine bed forming successive nips for driving the partly formed packages towards a sealing and severing station and for forming the required seal between the edge zones of the web, wherein the edge of at least one of at least one of the pairs of rollers, located adjacent the partly formed packages, is relieved whereby an air passage is formed within the tube at the point where the tube passes the relevant pair of rollers as it moves towards the sealing and severing station. The machine additionally comprises means for applying a vacuum to the tube adjacent the point where the edge zones of the web are brought together to form the tube.

Still further, <CIT> describes a method and equipment for the sealing of a film of material for wrapping for products, according to which film, wrapped about the products, which are fed in ordered sequence and arranged at predetermined intervals along a packaging line in order to form a tubular envelope having two specific parts respectively defined by two overlapped longitudinal edges and two opposed walls included between two adjacent products and destined to be connected by means of a heat seal, is pre-heated at the specific parts brushing them by means of a beam of radiant electromagnetic energy.

<CIT> describes a wrapping machine which includes a film former for shaping a continuous film of packaging material into a continuous tube, a film drive for drawing the continuous film of packaging material past the former and past a cutting and sealing station, a product infeed drive for feeding products to be packaged through the former into the continuous tube of packaging material so that the products are spaced apart from one another in the tube, and a motor-driven rotary cut/seal head at the cutting and sealing station for cutting and sealing the continuous tube of packaging material as each product moves through that station. The wrapping machine also includes independent closed-loop servo-control circuits for the film drive, the product infeed drive, and the cut/seal head drive, each of which is responsive to a desired velocity control signal. The wrapping machine also includes a first encoder on the shaft of a roller driven by the moving film a second encoder coupled to the product infeed drive, and a resolver coupled to the cut/seal head drive. A microprocessor-based controller (MBS) is coupled to the encoders, the resolver, and the servo loops for the infeed, film feed, discharge and cut/seal head drives. It derives a desired infeed velocity signal and a cut/seal head velocity profile signal based upon a film drive motor tachometer and outputs these desired velocity signals to the respective servo loops for the product infeed drive and the cut/seal drive. The controller is further responsive to the film travel encoder, film eyespot sensor, infeed travel encoder and pusher sensor outputs to adjust the product infeed velocity to maintain proper orientation of the products relative to the film. The controller is likewise responsive to the sensor inputs to adjust the cut/seal head velocity to maintain proper orientation of cutting and sealing relative to the film and product positions.

Depending on the characteristics of the sealing material, the sealing machine has to be adjusted so as to ensure proper sealing. Converting of the machine to take into account different properties of the sealing material is, however, labor-intensive and results in downtimes of the machine.

in view of the above, one object addressed by the present disclosure is to increase the usability of a sealing machine in view of changing characteristics of sealing material used while at the same time reducing the downtimes involved in adjusting the sealing machine to sealing material properties.

This object is addressed by the sealing machine for sealing a sealing material by heating a fin of a sealing material wrapped around a product according to independent claim <NUM> and a method for sealing a sealing material by heating a fin of the sealing material wrapped around a product by a sealing machine according to independent claim <NUM>. Preferred embodiments of the present disclosure are provided in the dependent claims.

According to the invention, a sealing machine for sealing a sealing material by heating a fin of a sealing material wrapped around a product is provided, the sealing machine comprising, in a transport direction of a sealing material, a pair of tracking rollers for tensioning a sealing material and a pair of heating rollers for sealing a sealing material by applying heat to a fin moved between the set of heating rollers, wherein the pair of tracking rollers and the pair of heating rollers are driven independently. Furthermore according to the invention, the sealing machine comprises, downstream of the pair of tracking rollers, a second pair of heating rollers, wherein the second pair of heating rollers can be disabled so as to not contact a fin moved between the second pair of heating rollers.

In the context of the present disclosure, the independent driving of the pair of tracking rollers and the pair of heating rollers is to be understood as meaning that characteristics of the rotation of the pair of heating rollers (including for example the rotational position, the rotational speed or the rotational acceleration) can be controlled and adjusted independent from the corresponding characteristics of the pair of heating rollers and vice versa. Particularly, the rotational speed of the tracking rollers can be controlled so as to be different from the rotational speed of the pair of heating rollers.

In summary, the above may particularly be understood as meaning that the pair of tracking rollers and the pair of heating rollers are driven independently from each other.

Within the present disclosure, it is encompassed that even though the rotational characteristics of the pair of tracking rollers and the pair of heating rollers can be adjusted and controlled independently, they may nevertheless, when in use, have the same rotational velocity depending on the circumstances. It is further encompassed that the characteristics of the rotation (or generally movement) of the pair of heating rollers differs from the pair of tracking rollers.

By independently driving the pair of tracking rollers and the pair of heating rollers, different requirements regarding the tension applied to the sealing material can be realized without having to physically adjust the sealing machine. Thereby, downtimes are reduced while at the same time allowing for adjustment of the sealing machine to changing sealing material properties.

The additional heating rollers can be provided, for example, downstream of the pair of tracking rollers but upstream of the pair of heating rollers or they can be provided even further downstream of the pair of heating rollers. Providing two pairs of heating rollers where one of the pairs of heating rollers can be moved between a disabled state, where it does not contact the fin, and an enabled state, where it is in contact with the fin, can be advantageous in cases of sealing material being used that requires two heating rollers for realizing reliable tensioning of the fin, thereby also improving the quality of the sealing for example in case of sealing material being used that is more difficult to stretch.

In one embodiment, a first drive is associated with the pair of tracking rollers and a second drive is associated with the pair of heating rollers, wherein the first drive and the second drive are independent from each other.

Providing two independent drives, for example a first servomotor and a second servomotor, realizes the independent driving of the pair of tracking rollers at the pair of heating rollers in a reliable and technically simple way.

In a more specific embodiment, the second pair of heating rollers is movable in a plane that is substantially perpendicular to the transport direction of the sealing material between a sealing state where the second pair of heating rollers can contact a fin moved between the second pair of heating rollers and a disabled state where the second pair of heating rollers cannot contact a fin moved between the second pair of heating rollers.

Thereby, a reliable moving away of the second pair of heating rollers so as to disable them or enable them is provided. Unintended stretching of the fin by means of the second pair of heating rollers is thereby avoided reliably.

In a further embodiment, the sealing machine comprises an actuation mechanism for moving the second pair of heating rollers.

This actuation mechanism can, for example, be automatically, like a servomotor, and can be, for example, controlled via the control unit of the sealing machine, for example. Alternatively, the actuation mechanism may comprise or may be a manually movable mechanism like, for example, a handwheel or a lever. An operator actuating the handwheel or the lever can then switch the second pair of heating rollers between the enabled and the disabled state.

In one embodiment, the second pair of heating rollers is driven jointly with the pair of heating rollers or the second pair of heating rollers is driven independently from the pair of heating rollers and the tracking rollers.

Jointly driving may encompass that a single driving mechanism, for example a servomotor, is provided for driving both pairs of heating rollers. This simplifies the construction. Alternatively, realizing the first pair of heating rollers and the second pair of heating rollers as independently driven from each other and from the pair of tracking rollers allows for adjusting the tension of the fin of the sealing material also between the heating rollers, which can be advantageous in applications where the sealing material requires additional tensioning.

It can also be provided that the sealing machine comprises a control unit, wherein the control unit is adapted to enable and disable the second pair of heating rollers based on an input of a user.

The control unit can, for example, be adapted to enable or disable the second pair of heating rollers depending on the sealing material actually used. If, for example, the user provides an input specifying the sealing material or if the sealing material is identified in another way, for example by scanning a barcode, the control unit can automatically or at least semi-automatically (for example upon and in response to confirmation of the operator of the sealing machine) control the second pair of heating rollers so as to enable or disable them.

Reliable control of enabling or disabling the second pair of heating rollers is thereby provided.

In a more specific realization, the control unit is adapted to control the driving of the pair of tracking rollers and/or the pair of heating rollers and/or the second pair of heating rollers.

Controlling the driving may, for example, encompass controlling the rotational speed and/or acceleration of rotation and/or rotational position of the respective pair of tracking rollers and the pair of heating rollers and potentially also the second pair of heating rollers. Thereby, specific characteristics regarding the tensioning and the movement of the sealing material can be realized.

The present disclosure further relates to a method for sealing a sealing material by heating a fin of the sealing material wrapped around a product by a sealing machine, the sealing machine comprising, in a transport direction of the sealing material, a pair of tracking rollers that tension the sealing material and a pair of heating rollers that seal the sealing material by applying heat to the fin of the sealing material moved between the pair of heating rollers, wherein the pair of tracking rollers and the pair of heating rollers are driven independently, wherein the method comprises adjusting a tension of the sealing material by driving the pair of tracking rollers and the pair of heating rollers. According to the invention, it is provided that the sealing machine comprises, downstream of the pair of tracking rollers, a second pair of heating rollers, wherein the second pair of heating rollers can be disabled so as to not contact a fin moved between the second pair of heating rollers, wherein the method comprises disabling or enabling the second pair of heating rollers depending on a tension to be applied to the sealing material.

With this method, a reliable tensioning of the sealing material is realized also in cases where different kinds of sealing material are used that require different tensioning.

By the second pair of heating rollers, also sealing materials that require different tensioning can be performed without this requiring structural modification of the machine that would be time consuming.

The drives can be realized as servomotors, for example. This realizes flexible control and at the same time independent movement of the tracking rollers and heating rollers.

In a more specific embodiment, the second pair of heating rollers is moved in a plane that is substantially perpendicular to the transport direction of the sealing material between a sealing state where the second pair of heating rollers contacts a fin moved between the second pair of heating rollers and a disabled state where the second pair of heating rollers does not contact a fin moved between the second pair of heating rollers.

The movement in a plane that is substantially perpendicular to the transport direction may encompass also cases where the movement of the second pair of heating rollers (or at least one roller of this second pair of heating rollers), when seen from above the arrangement of rollers, occurs in a curved plane or in a direction that is slightly inclined (for example by up to <NUM>° or up to <NUM>°) compared to a plane that is exactly perpendicular to the transport direction of the sealing material and/or the fin. Each of those embodiments can be advantageous to realize a simple construction while ensuring flexible movement of the second pair of heating rollers.

In one embodiment, the sealing machine comprises an actuation mechanism for moving the second pair of heating rollers between the disabled state and the sealing state.

This actuation mechanism can be implemented automatically or manually or semi-automatically, for example requiring user interaction or at least a user input or confirmation for actuating the second pair of heating rollers.

In a further embodiment, the second pair of heating rollers is driven jointly with the pair of heating rollers or wherein the second pair of heating rollers is driven independently from the pair of heating rollers and the tracking rollers.

Depending on the characteristics of used sealing material, it can be advantageous to jointly drive the first pair of heating rollers and the second pair of heating rollers to thereby ensure that no different tensioning between the first pair of heating rollers and the second pair of heating rollers is applied. Alternatively, it can be advantageous if such different tensioning is possible.

In a further embodiment, the sealing machine comprises a control unit, wherein the control unit switches the second pair of heating rollers between the disabled state and the sealing state based on an input of a user; and/or
wherein the control unit is adapted to control the driving of the pair of tracking rollers and/or the pair of heating rollers and/or the second pair of heating rollers.

With this, the switching between the enabled state and the disabled state can be user-controlled otherwise automatically, reducing the interaction of a user or operator with the sealing machine, thereby reducing the risk of injuries.

<FIG> shows a schematic side view on a sealing machine <NUM> according to one embodiment of the present disclosure.

Sealing machines are generally known to comprise a transporting device <NUM> for transporting products <NUM>, like for example packages with food inside or any other kind of products that need sealing with a sealing material.

These packages are transported along a transport direction T schematically depicted with the arrow along the transporting device <NUM>. Particularly, the transporting device may be implemented as a chain conveyor or other suitable conveyor for transporting the packages.

Additionally, the sealing machine <NUM> according to the present disclosure may comprise a provisioning system <NUM> for providing a sheetlike material. This provisioning system <NUM> may particularly comprise a sealing material roll <NUM> and further elements <NUM>, like deflection rolls, that facilitate transporting of the sheetlike material so that it is provided, in the region of the transporting device <NUM>, below the products <NUM>.

The sealing machine according to the present disclosure is intended to fold the sheetlike material around the products so that a film of material is wrapped around the products, leaving, on top of the packages in the depiction provided here, a fin where the edges of the sealing material, in the transport direction T of the products, contact each other. This may realized by employing a forming set <NUM> that forms the sheetlike material so as to assume the respective shape so that the fin <NUM> (only schematically depicted here) is provided.

Downstream of the forming set <NUM>, there may be provided a sealing station <NUM> of the sealing machine. This sealing station may at least comprises a pair of tracking rollers <NUM>. These tracking rollers, as will be explained further below with reference to <FIG>, contact the fin <NUM> of the sealing material and, due to the tracking rollers of the pair of tracking rollers <NUM> being rotated in the direction of the transport direction T, tension the fin <NUM> and therefore the sealing material. Downstream of this pair of tracking rollers <NUM>, at least one pair of heating rollers <NUM> may be provided that can apply heat to the fin <NUM> that is moved between the pair of heating rollers <NUM>. This can for example be realized by heating the material of the heating rollers of the pair of heating rollers <NUM> so that, by physically contacting the fin <NUM>, a heat transfer occurs that heats the sealing material forming the fin.

Thereby, a sealing of the fin and thereby at least a longitudinal sealing of the product <NUM> is achieved.

Downstream of the sealing station <NUM> in the transport direction T of the products, further stations may be provided like, for example, a cross-sealing station that applies a sealing to the sealing material that extends in a direction substantially transverse to the transport direction T so as to seal the products also in the transverse direction.

<FIG> shows a top view of the sealing station <NUM> as was depicted as sealing station <NUM> in <FIG>.

As is seen here in more detail, the sealing station <NUM> comprises, in transport direction T of the fin <NUM> of the sealing material, a pair of tracking rollers <NUM>. The tracking rollers are rotatable preferably about an axis of rotation that is perpendicular to the transport plane in which the products are transported. The axis of rotation will thus be perpendicular to the depicted plane of <FIG>. The tracking rollers of the pair of tracking rollers <NUM> can be provided as flat, cylindrically shaped or conically shaped discs and may extend, in a direction perpendicular to the plane depicted here, about <NUM> or <NUM> or <NUM> or any value in between or more.

Preferably, the tracking rollers have a surface structure that has a comparably high friction coefficient with respect to the sealing material.

Particularly, the surface of each of the tracking rollers may comprise material having a friction coefficient with respect to a sealing material made from PET or other plastic materials that is larger than the friction coefficient of iron or PET or plastic with respect to the sealing material. Thereby, high friction between the fin <NUM> and the tracking rollers of the pair of tracking rollers <NUM> is ensured, resulting in reliable gripping and tensioning of the fin <NUM>.

As is seen in <FIG>, the fin <NUM> of the sealing material is transported between the tracking rollers of the pair of tracking rollers <NUM> along the transport direction T. Preferably, a drive, like a servomotor, <NUM> is associated with the pair of tracking rollers <NUM>. While only one drive <NUM> is shown here that is associated with both tracking rollers for causing them to rotate, it can be provided that each of the tracking rollers is associated with one drive so that, in addition to the one drive <NUM> shown here, a further drive is provided for driving or rotating the other one of the tracking rollers of the pair of tracking rollers <NUM>.

As is further shown in <FIG>, in the transport direction of the fin <NUM>, there is provided a first pair of heating rollers <NUM> and a second pair of heating rollers <NUM>. According to an example of the present disclosure, there may only be one pair of heating rollers <NUM>. According to the invention, the second pair of heating rollers (either the pair <NUM> or the pair <NUM>) is switchable between an enabled state where the pair of heating rollers gets in contact with a fin <NUM> of the sealing material and a disabled state where they do not contact a fin of the sealing material.

The heating rollers of each of the pairs of heating rollers <NUM> and <NUM> are likewise provided so as to get into contact with the fin <NUM> of the sealing material and are further adapted to applying heat to the fin of the sealing material in the region of contact where the heating rollers contact the fin. By pressing together the edges of the sealing material forming the fin <NUM> and at the same time applying heat to this pressed-together section, a sealing of the fin <NUM> of the sealing material is obtained, thereby applying a longitudinal sealing of the sealing material along the fin.

The heating rollers of the pairs of heating rollers can be structured in the same way as the tracking rollers and may additionally or alternatively also be provided with a high friction coefficient material as explained above with respect to the tracking rollers. Thereby, the physical contact of the heating rollers with the to be heated sealing material may be improved, resulting in a reliable sealing.

According to embodiments of the present disclosure, the pair of heating rollers <NUM> and/or <NUM> are associated with a further drive <NUM> that can be driven independent from the drive <NUM> for the pair of tracking rollers <NUM>. Thereby, the pairs of heating rollers (or at least one of them) can be driven independent from the pair of tracking rollers, allowing for adjusting the tension applied to the fin <NUM> of the sealing material between the pair of tracking rollers <NUM> and the pair of heating rollers <NUM> and/or <NUM>.

While, in some embodiments, the drive <NUM> and <NUM> are integrated as a single drive, it is preferred that there are provided two structurally independent drives, like two servomotors, where one of them is associated with the pair of tracking rollers <NUM> and one of them is associated with the pair(s) of heating rollers <NUM> and/or <NUM>.

Additionally, it can be provided that each pair of heating rollers <NUM> and <NUM> is associated with one drive so that instead of a single drive <NUM> for driving the first and second pair of heating rollers, two drives can be provided in some embodiments where the first drive may be associated with the first pair of heating rollers <NUM> and the second drive may be associated with the second pair of heating rollers <NUM>. Additionally or alternatively, like for the pair of tracking rollers <NUM>, it can also be provided that each of the heating rollers of each pair of heating rollers is associated with a single drive.

Furthermore, in some embodiments, there can be provided at least one actuation mechanism <NUM> and/or <NUM> for moving at least one pair of the heating rollers <NUM> or <NUM> in a plane that is substantially perpendicular to the transport direction T as will be further explained with respect to <FIG> and <FIG>. The actuation mechanisms <NUM> and <NUM> can, for example, be provided as a spindle that allows for adjusting the distance of the heating rollers of a pair of heating rollers <NUM> and/or <NUM> relative to the fin <NUM> of the sealing material or relative to a central axis of the transporting device <NUM> as described in relation to <FIG>.

Thereby, it is possible to increase the distance of the heating rollers of a pair of heating rollers to the fin, thereby disabling the heating rollers when they are provided in a distance that is insufficient for making contact with the fin. With this, a pair of heating rollers, for example the pair <NUM> or the pair <NUM>, can be disabled so as to not heat the fin <NUM>. This can realize at least one advantage of preventing excessive heat being provided to the fin <NUM> (thereby potentially causing damage to the fin <NUM>) and/or adjusting the tension applied to the fin of the sealing material. This can be advantageous in cases where the sealing machine according to embodiments of the present disclosure is to be used with different kinds of sealing material. For example, sealing material having a comparably large material thickness requires more heat and potentially also more tension to be applied in order to provide a reliable seal to the fin <NUM>. In that case, the two pairs of heating rollers <NUM> and <NUM> may be used and provided in the enabled state where they make contact with the fin <NUM>. Other sealing materials, particularly thinner sealing materials, may require less heat and/or less tension. In such cases, it may then be sufficient and even advantageous to only use one of the pair of heating rollers. In such cases, at least one actuation mechanism may be actuated so as to move one of the pairs of heating rollers <NUM> and <NUM> from the enabled state (also referred to herein as sealing state) to the disabled state.

While the embodiment of <FIG> depicts two actuation mechanisms <NUM> and <NUM>, it can be provided that only one actuation mechanism is provided so as to only provide one pair of heating rollers in a manner that this pair can be enabled or disabled.

In this respect, in one embodiment, the pair of heating rollers that comes first in the direction downstream of the pair of tracking rollers <NUM> can be provided with an actuation mechanism like the actuation mechanism <NUM> or the second pair of heating rollers <NUM> can be provided with an actuation mechanism <NUM>. This may depend on the circumstances and the actual requirements of the sealing material. If both pairs of heating rollers are provided with corresponding actuation mechanisms <NUM> and <NUM>, the highest flexibility is obtained with respect to enabling and disabling heating rollers.

In <FIG>, a control unit <NUM> is shown that is preferably in communication with the actuation mechanism <NUM> and/or the actuation mechanism <NUM> for enabling and/or disabling one of the pairs or both pairs of heating rollers <NUM> and <NUM>. Additionally, it can be provided that the control unit <NUM> is communicatively coupled with the drives <NUM> and/or <NUM> for driving the pair of tracking rollers and the pair of heating rollers or the pairs of heating rollers. In some embodiments, a user can provide an input via an input device (like a touchscreen or a keyboard) to the control unit <NUM> indicating that the actuation mechanism for enabling or disabling a pair of heating rollers is to be actuated so as to switch the pair of heating rollers between the enabled state and the disabled state.

Additionally or alternatively, the control unit <NUM> can be used to independently control the drives <NUM> and <NUM> so as to independently control the rotation of the pair of tracking rollers <NUM> and the pair(s) of heating rollers <NUM> and/or <NUM>. Thereby, the tension applied to the fin can be adjusted as need be. Particularly, the control unit <NUM> can be realized as a computer with an associated memory.

In some embodiments, the memory may contain data that is indicative of requirements regarding the enabling and/or disabling of pairs of heating rollers and the required tension for a specific sealing material. Depending on the sealing material used, the control unit can then automatically adjust the drives <NUM> and <NUM> and/or the enabling and/or disabling of the pairs of heating rollers by controlling the actuation mechanism(s) <NUM> and/or <NUM>. For example, a user can input information identifying the sealing material to be used and, based on this input information, the control unit <NUM> can provide corresponding adjustments and control to the drives <NUM> and/or <NUM> or actuate one or both of the actuation mechanisms <NUM> and <NUM>.

Additionally or alternatively, the control unit may automatically identify the sealing material (for example via an identification of the sealing material by means of the roller <NUM>. It may comprise specific marks or barcodes that can be identified by the control unit, for example by using specific identification means like a code scanner. Based on the identified sealing material, the adjusting of the characteristics of the drives <NUM> and <NUM> and the enabling and/or disabling of the pairs of heating rollers can be controlled.

<FIG> and <FIG> show one mode of adjusting the pairs of heating rollers depending on the needs with respect to the tensioning and/or heating of the fin of the sealing material. In <FIG>, the products <NUM> are enveloped by the sealing material <NUM>. As is shown in the slightly enlarged view that is taken in a plane perpendicular to the transport direction T in <FIG>, this enveloping is realized so that the sealing material <NUM> forms a fin <NUM> above the product <NUM>. This fin <NUM> is then transported in the transport direction T first to the pair of tracking rollers <NUM> that rotate with a velocity so as to apply a required tension to the fin <NUM> and also optionally pressing together the two edges of the sealing material <NUM> that formed the fin <NUM>.

Subsequently, in the transport direction T, the fin <NUM> passes the two pairs of heating rollers <NUM> and <NUM>. In the situation depicted in <FIG>, both pairs of heating rollers <NUM> and <NUM> are enabled, where the first pair of heating rollers in the transport direction T downstream of the pair of tracking rollers <NUM> is adjustable, i.e. is associated with corresponding actuating means as explained in relation to <FIG>. In the here depicted enabled state, the rotational axes of the two heating rollers of the pair of heating rollers <NUM> may have a distance D1 that may be approximately equal (but slightly larger than) the sum of the radii of the heating rollers of the pair of heating rollers <NUM>. Particularly, the distance D1 may be larger than the sum of the radii by an amount that corresponds to the thickness of the sealing material forming the fin <NUM> or it may correspond to <NUM>% or <NUM>% or <NUM>% or less of that amount so as to ensure reliable pressing together of the sealing material when heating the fin.

This situation may be assumed, as explained above, in cases where the sealing material might require, for example, additional tensioning or heating.

Claim 1:
A sealing machine (<NUM>) for sealing a sealing material by heating a fin (<NUM>) of a sealing material wrapped around a product (<NUM>), the sealing machine (<NUM>) comprising, in a transport direction (T) of a sealing material, a pair of tracking rollers (<NUM>) for tensioning a sealing material and a pair of heating rollers (<NUM>) for sealing a sealing material by applying heat to a fin (<NUM>) moved between the pair of heating rollers (<NUM>), wherein the pair of tracking rollers (<NUM>) and the pair of heating rollers (<NUM>) are driven independently, characterized in that the sealing machine (<NUM>) comprises, downstream of the pair of tracking rollers (<NUM>), a second pair of heating rollers (<NUM>), wherein the second pair of heating rollers (<NUM>) can be disabled so as to not contact a fin (<NUM>) moved between the second pair of heating rollers.