Device and method for applying glue

A device for applying glue onto labels, includes a drum rotatable about a predetermined rotational axis and, a glue application unit for applying glue onto an external surface of the rotatable drum. The glue application unit includes a receiving space for receiving the glue as well as a supply unit for applying the glue to the receiving space which is arranged relative to the drum such that any glue present in the glue application unit contacts the drum in a predetermined contact area. The glue application unit includes a first wall element, which contacts the drum during operation, and a second wall element arranged behind the first wall element in the direction of movement of the drum and which also contacts the drum. At least one wall element is elastically pressed against the external surface of the drum.

BACKGROUND OF THE INVENTION

The present invention relates to systems for labelling containers and in particular also to devices for applying glue onto labels. It is known in the area of beverage producing industries to provide containers with labels. In this respect it is known on the one hand to use labels that are designed to be self-adhesive as well as labels onto which glue is initially applied so as to subsequently attach the labels provided with glue to the containers. In the latter type of labels, so-called glue drums are known which are used for applying glue onto the rear sides of the labels. In the prior art, the glue is applied by means of a so-called glue scraper on a drum, said glue scraper resting on the glue drum in a pivotable and tangential manner. In order to reliably fulfil its function, a high degree of accuracy with regard to the position between the glue drum and the glue scraper is required here. It is also possible here for the glue scraper to be mechanically advanced onto the glue drum. Further, in the direction upstream of a glue drum of this type a label scraper is usually provided which has the function of rejecting labels that are drawn into the gluing unit. These components make the cleaning of and access to the gluing unit very difficult for the operator.

The present invention is therefore based on the object of providing a glue application device which reduces the requirements in respect of the above-mentioned accuracy.

SUMMARY OF THE INVENTION

An apparatus according to the invention for applying glue onto labels comprises a drum that is rotatable about predetermined rotational axis as well as a glue application unit for applying glue onto an external surface of the rotatable drum. Here, the glue application unit includes a receiving space for receiving the glue as well as a supply unit for supplying glue to the receiving space. Further, the glue application unit is arranged in such a way that any glue present in the glue application unit comes into contact with the drum in a predetermined contact area, with said glue application unit having a first wall element which contacts the drum during operation, as well as a second wall element which is arranged behind the first wall element in the direction of movement of the drum and which also comes into contact with the drum.

According to the invention, at least one wall element is pressed against the external surface of the drum in an elastic manner or under the effect of a spring force.

In particular, at least one wall element is elastically pressed against the external surface of the drum during operation of the device. A wall element is to be understood in particular as an element which extends in a plane or a pulling direction and which is part of the glue application unit, but which comes into contact with the glue drum. As a result of this elastic contact between the wall element and the roller, an improved sealing of the receiving space is achieved. Also, in this way a more uniform application of the glue on the drum may be enabled. Advantageously, the wall contacts the drum over the entire extension of said wall, which means in particular its extension in the longitudinal direction or the direction of the rotational axis of the drum.

Thus, the glue application unit includes in particular a hollow chamber that may be filled with glue. By means of the two wall elements or separate doctor blades, the glue layer is pulled off from the glue drum. Due to the geometry and the mechanical properties of these doctor blades, any run-out errors are compensated, with the glue pattern remaining unchanged.

Advantageously, both wall elements are pressed against the external surface of the drum especially in an elastic manner. A wall element that is arranged behind the first wall element in the direction of movement of the drum is to be understood to mean that in the working operation at a predetermined point in time, these will rest on two predetermined areas of the external wall of the drum, said areas being offset from one another in the circumferential direction of the drum. Between the two contact areas, the receiving space for receiving the glue is formed.

Advantageously, therefore, at least one wall element and preferably both wall elements delimit the receiving space. In this way, the number of components of the device can be further reduced and the accessibility of the system is enhanced.

In a further advantageous embodiment, the external surface of the drum has a structured surface at least in sections. This structured surface allows the application of the glue onto the external surface of the drum to be improved. Thus, for example, the external surface may have indentations extending in the direction of the axis of the glue drums, which indentations are in one embodiment for example homogeneously distributed on the external surface of the drum. It would further be possible for these indentations or structures to be provided only in some areas in the circumferential direction of the drum. Advantageously, these indentations have a depth between 0.02 and 0.08 mm and preferably between 0.03 and 0.05 mm. This embodiment of these indentations was described in detail in the so far unpublished German Patent Application DE 10 2010 000 182.1. The disclosure of this patent application is included by reference in the disclosure of the present patent application.

In a further advantageous embodiment, the external surface of the drum also has a smooth surface at least in sections. Preferably, it is also possible here that, as mentioned above, the smooth and the structured surfaces alternate in the circumferential direction of the drum. In this way it is possible to apply glue during operation only onto predetermined areas of the surface (in particular the structured areas), but not onto other areas (in particular the smooth areas).

In a further advantageous embodiment, the device has a first sealing means which seals the receiving space against the environment and which adjoins to the sealing space in the direction of the rotational axis. Here, the sealing means advantageously contacts the external surface of the drum in a predetermined sealing area. Preferably, the resulting receiving space for the glue will therefore be sealed by means of said sealing means towards the bottom and particularly preferably also towards the top.

Advantageously, the external surface of the drum has a smooth external surface in the sealing area. In this way, the sealing effect between the drum and the sealing means may be improved.

It is further possible for the glue application unit and/or the glue scraper to be implemented with a heater or without a heater. To simplify the cleaning process, the glue application unit may here be completely removed or simply swung out.

Therefore, apart from the above-mentioned first sealing means, a second sealing means is advantageously also provided, with the receiving space (in particular in the direction of the rotational axis of the drum) advantageously being arranged between these two sealing means.

In a further advantageous embodiment, the wall elements extend substantially along a rotational axis of said drum. In this connection it is in particular possible for the wall elements to be arranged parallel to said rotational axis.

In a further advantageous embodiment, the first wall element extends in a direction which includes an angle with a geometrical tangent on the drum, which is between 0° and 70°, preferably between 10° and 60° and particularly preferably between 10° and 30°. Thus, the wall element rests against the drum particularly in the contact area under a very shallow angle, as a result of which any frictional wear between the drum and the wall element is minimised even under the effect of a spring force. Thus, the wall element may be an elastic wall element, which may be made for example from an elastic material and which will press against said drum. As a result of this angular embodiment, scraping and/or applying glue onto the drum is facilitated.

In a further advantageous embodiment, the glue application unit includes a discharge unit for discharging glue from the receiving space. This discharge unit is preferably arranged upstream of the supply unit. By means of this approach it can be ensured that the glue present inside the receiving space will always be under a substantially constant pressure.

In a further advantageous embodiment, the glue application unit is implemented to be replaceable. This means that it is in particular possible for a support for accommodating the glue application unit to be provided. It is also possible to use glue application units of different heights. This approach makes it possible to replace the unit with an identical one or with a new variant of a glue application unit. The glue scraper may be provided with different geometries of the doctor blades. Thus, for example, it is conceivable to use a glue scraper as part of an assembly. In the case of labels with a low height, a correspondingly low glue scraper or a lower glue application unit may be used, and in this way glue contamination and glue consumption may be minimised.

In a further advantageous embodiment, the glue application unit is arranged to be in a fixed position in its mounted condition, i.e. in particular not adjustable in relation to the drum. This means that in contrast to the prior art, this embodiment exactly provides for the glue application unit not to be adjustable in relation to the drum. The compensation of for example surfaces with unevenness on the glue drum is, as mentioned above, achieved by providing elastic walls or doctor blades.

In a further advantageous embodiment, the device includes a sensor unit which determines a position of the glue application unit in relation to the drum. In this way, this sensor can be used to poll the position of the glue application unit. The glue flow can be controlled as a function of the position. Here, too, for example when a label is pulled into the glue unit, the operator may be prompted to rectify the fault. Apart from that, it may also be provided for the machine not to start until after a label has been removed.

It is further possible to provide a label rejector, which is particularly preferably disposed directly on the glue application unit. In this way, an altogether error-tolerant and flexible scraper system may be provided at low costs.

The sensor unit mentioned above, which determines the position of the glue application unit in relation to the drum, may here determine the position for example by optical means, but also for example via the electric resistance between the wall elements and the drum.

In a further advantageous embodiment, the device includes a rotatable cylinder, on the lateral surface or external surface of which the labels may be fixed, with the rotatable drum advantageously contacting the labels disposed on the lateral surface in sections. In this way, the glue may be applied to the rear side of the labels. Advantageously, the labels are fixed to the lateral surface of the rotatable cylinder using vacuum.

The present invention is further directed to a method for applying glue onto a glue drum, wherein glue is fed in one step to a receiving space formed by a glue application unit.

Further, a drum is rotated about a predetermined rotational axis, with the glue application unit being arranged in such a way that any glue present in the glue receiving space contacts the external surface of the drum. Further, the glue is applied by means of a wall which delimits the receiving space, said wall being elastically pressed against the external surface of the drum.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1shows a schematic top view of a labelling machine that allows labels to be attached continuously with high efficiency onto articles which are continuously supplied in a single-lane row. The articles may here be cans, glass bottles, PET bottles or the like.

The labelling machine50includes an infeed conveyor51, an inlet star wheel54with an upstream dividing worm53, a guiding arc56, a carousel57with a plurality of rotary plates58arranged in equal intervals on a common pitch circle, an outlet star wheel55and an outfeed conveyor52. The transport elements moving the articles through the labelling machine can be continuously driven in a manner synchronous in respect of speed and position.

In the circulation area between the inlet star wheel54and the outlet star wheel55, a labelling unit50for applying labels onto the articles is provided on the outer periphery of the carousel57. The labelling unit50includes two label roll receptacles59and a splicing station60positioned therebetween, a cutting unit63, a glue unit1having a vacuum cylinder30for transferring a pre-cut label having glue applied to its leading and trailing edges onto a passing article. The process of labelling an article is carried out in detail as follows:

The article supplied from the infeed conveyor51is introduced into the inlet star wheel54in an appropriate position in association with the laterally disposed dividing worm53and is pushed by said inlet star wheel in cooperation with the guiding arc56located opposite thereto in a continuous movement onto a rotary plate of the rotating carousel57. There, the article is axially clamped on a rotary plate rotatable therewith by a centring bell (not shown) which is controlled relative to the rotary plate and can be lifted and lowered, and is fed in by the circulatory movement of the carousel57tangentially towards the vacuum cylinder30of the labelling unit.

At the same time, the label strip is pulled off from a label strip roll59in a controlled manner, is guided past a sensor (not shown here) for detecting any print marks or the print pattern and is cut in the cutting unit63associated with the sensor in accordance with the printing pattern or the crop marks. The severed label, which is located on the rotating vacuum drum64with the printing pattern facing outwards during the cutting process, is transferred to the vacuum cylinder30after the severing process, from where it is guided past the glue drum2with its rear side facing outwards and is provided with glue in a predetermined type-dependent area of the label. This label provided with glue is supplied tangentially towards the carousel57on which the articles are located. The label with the glue applied thereon comes in contact with the article and is rolled onto said article by a suitable movement of this article.

Upon passing the labelling unit and upon completion of the attachment of the label onto the article, the labelled article then arrives at the outlet star wheel55and is transferred onto the outfeed conveyor52.

FIG. 2shows a schematic top view of the cutting unit63and of the glue unit1, which is illustrated in a patent application that was recently filed by the applicant. The label strip pulled off from the label strip roll59is fed via an idle roller65and the roller pair66to the cutting unit63. Here, the label strip rests against the vacuum drum64that rotates in the direction of the arrow67and is cut by a severing element68in correspondence with the crop marks or the printing pattern.

These label pieces are transferred to the vacuum cylinder30which rotates in the direction of the arrow69. The labels thus rest on the lateral surface23of the vacuum cylinder30. The vacuum cylinder30rotates about the Y axis. The lateral surface23of the vacuum cylinder2has elements (not shown) which respectively receive the beginning and/or the end of the label piece. It can be seen from this fact that in the case of different label lengths, other vacuum cylinders will have to be used in order to match the elevations to the label lengths.

During the movement of the label pieces located on the lateral surface23of the vacuum cylinder30past the glue drum2, the elevations of the drum cause the respective label pieces to come into contact with the glue drum in a predetermined area, so that these are provided with glue at the predetermined positions. These strips of glue are needed to glue the label pieces onto the articles to be labelled. The transfer of the label pieces provided with strips of glue is carried out in the position where the rotary plates of the carousel57come into contact with the lateral surface23of the vacuum cylinder.

In order to be able to provide the label piece as just described with strips of glue, a glue unit1is required. The glue unit consists of a glue tank5, if necessary a glue heater71, a gluing strip72, a glue pump73and quick-clamping elements74. The hot glue which was supplied to the glue tank5and was liquefied by the glue heater71so that it can be processed is pumped by the glue pump73to the glue tank5and is fed by means of the glue drum2to the external surface2aof the latter. The gluing strip72is fed so close to the glue drum2that it will remove any excess glue around the axis of the glue drum during rotation of the glue drum2.

The components just described, which are associated with the glue unit1are mounted on a glue unit base plate75. The glue unit base plate75can be integrated in its entirety into the labelling unit. To this end, the glue unit1is placed against two strips (not shown here) of the labelling unit and is removed from the labelling unit using a quick-clamping element on the glue unit base plate75together with all its components and is replaced with another glue unit1.

FIG. 3shows a device for applying liquids in labelling machines according to the prior art. This device100includes a drum102onto which glue is to be applied. Reference numeral105relates to a supply chamber or a receiving space, in which glue is present, with an opening105abeing further provided which opens from this supply chamber105towards the drum102. Reference numeral110relates to a scraper which in the working position has a smaller radial distance from the drum than the actual glue application unit104. Through this opening105a, substantial amounts of glue, partly also unintentionally, may exit from the supply chamber105.

Reference numeral107inFIG. 3relates to an axis which is parallel to the rotational axis of the glue drum102and in relation to which a housing7is pivotably arranged via a support108. Reference numeral109identifies a gluing strip.

FIG. 4shows a view of a glue unit1according to the invention. This glue unit includes a glue application unit4shown inFIG. 5. This glue application unit4includes here a receiving space16for receiving the glue, which glue can be supplied via a supply unit18to the receiving space16. Reference numeral12identifies a first wall element which is here part of the glue application unit4, and reference numeral14identifies a second wall element. The glue application unit4is disposed on a support24. This support24in turn may be disposed in a fixed position relative to the drum2.

FIG. 6shows two generally schematic views for illustrating a use of glue application units4. Here, too, reference numeral2again relates to a glue drum and reference numeral4respectively relates to the glue application unit. Reference numeral5respectively identifies a glue tank in order to supply the glue to the glue application unit4. In the case of the left-hand part inFIG. 6, a comparatively small label10is fed to the glue drum, and correspondingly also the glue application unit is relatively short in the longitudinal direction L of the glue drum. In the case of the right-hand part of the figure, a comparatively wide label10is fed to the glue drum2, and correspondingly also a longer glue application unit4is used.

FIG. 7shows a lateral view for illustrating the invention. Here, again, the drum2is shown which has a surface2athat is structured here. In the lower and upper areas of the drum, non-structured or smooth surface areas2bare provided. Apart from that, non-structured areas2cmay be provided also in the circumferential direction of the drum. The area in which the glue contacts the drum, is contact area B.

The glue application unit4has here two sealing means which respectively rest against the non-structured or smooth areas2bof the glue drum. These sealing means may here be PTFE seals. The areas in which the sealing means22rest against the glue drum are also the respective sealing areas D.

Reference numeral18identifies a supply unit for supplying glue and reference numeral26identifies a return unit or a discharge unit for the glue. As mentioned above, the discharge unit for the glue is here disposed upstream of the supply unit18. Further, the glue application unit4can be heated, so that the glue in the receiving space16is also heated.

FIG. 8shows a further view of the device according to the invention. What can be seen here again are the receiving space16as well as the first wall element12and the second wall element14, each of which rest on the drum2. However, the angles under which the wall elements are disposed here relative to the tangent of the drum are represented too large. Further, support pieces12aor14amay be disposed on the wall elements, which press against the external surface2aof the drum. In this case, more specifically, even the two end pieces12aand14acould constitute the actual wall elements. It can be seen, however, that the two wall elements12and14delimit here the receiving space in the circumferential direction of the drum, so that glue can only exit in a targeted manner as a result of the rotation of the drum12.

FIG. 9shows a further lateral view of an arrangement according to the invention. What can be seen here again are the glue drum2as well as the two sealing means22which rest against the upper and lower edges of the glue drum2.

FIG. 10shows another view from the top onto a device according to the invention. What can be seen here in particular are the very shallow angles a, under which the two wall elements rest on the external surface2aor the tangent T thereof. What can further be seen is that the receiving space16is largely also disposed behind the two wall elements14and12. These two wall elements are here—as mentioned in the beginning—implemented to be elastic and therefore rest against the external surface2aof the drum2with a predetermined spring force.

The glue application unit is here supported in a pivotable manner and may advantageously also be implemented to be pneumatically switched off. In order to replace the glue drum2, for example for cleaning or for changing the glue type, a heating may be swung into a predetermined changing position. By means of some thermally insulated protection, any risk to the operator will advantageously be avoided. A position of the glue application unit can particularly preferably be multi-dimensionally adjusted in order to compensate for any alignment errors relative to the vacuum cylinder (not shown). Apart from that, also an integrated cable guide may be provided, which is used for protecting against glue contamination. Instead of using a module with a glue drum, also a module with a spray system may be attached via a predetermined interface.

Reference character P identifies the rotational direction of the glue drum2. In contrast to the devices known from the prior art, a rotation of the drum is possible here in both rotational directions. By means of this it is achieved that here two wall elements12,14are provided (with one wall element being provided upstream of the glue application point and the other wall element downstream of the glue application point, depending on the running direction), which respectively include support pieces12a,14a. More specifically, in this way a chamber is generated which allows an improved glue application. Also, as a result of the elastic effect of these wall elements or the support pieces, a correct adjustment of the wall elements12,14relative to the glue roller2will always be achieved independently from the temperature generated or from the wear of the materials used. In this way, an improved glue application is ensured.

The applicant reserves the right to claim all of the features disclosed in the application documents as being essential to the invention, in as far as they are novel over the prior art either individually or in combination.

LIST OF REFERENCE NUMERALS