Patent Grant
8904953
This application claims the priority of German number 10 2010 029 678.3 filed Jun. 2, 2010, hereby incorporated by reference.
1. Field of Invention
The invention relates to an apparatus for applying glue to regions of paper or plastic webs or paper or plastic web-sections. The apparatus includes a nozzle unit having a plurality of glue outlet openings and glue supply lines and a plurality of glue valves, via which the glue supply lines are provided selectively with glue. Each glue valve includes at least one tappet having a sealing head and at least one counter element, with which the sealing head can make sealing contact. The apparatus also includes a glue chamber, via which the glue is provided. The invention also relates to a method of producing the above-described apparatus for applying glue.
2. Description of the Prior Art
An apparatus of the type mentioned above is described in detail in the patent application DE 103 09 893. In the production of paper sacks, it is necessary to provide different components with adhesive. Initially, a tube is shaped out of a web or a plurality of webs forming a multilayered web, one or more traces of glue being applied in the longitudinal direction to regions of the web that are then overlapped by other regions of the web (so-called tube forming). The webs can be made of paper and/or plastic. The tube formed is separated into tube pieces, on which bottoms are molded subsequently, and adhesive is applied again to parts of these tube pieces for gluing the bottoms. Frequently, starch glue is used as the adhesive. Therefore, the word “glue” is used in place of the word “adhesive” in the following parts of this application without restricting the subject matter of the invention.
DE 103 09 893 suggests the use of apparatuses that apply the glue in the desired format by means of a plurality of glue valves instead of glue application rollers that carry the format-dependent plates and that have been in use for decades. The format, in which the glue is applied, can be influenced by suitably controlling individual valves in terms of time. Such apparatuses often comprise a nozzle unit comprising a plurality of glue outlet openings and glue supply lines for these glue outlet openings. Furthermore, the glue valves, by means of which the glue supply lines and thus the glue outlet openings can be provided selectively with glue, are disposed on this nozzle unit. Moreover, the nozzle unit comprises at least one glue chamber, by means of which glue can be provided. The glue is guided to the glue valves by means of glue lines. Glue can flow from the glue chamber through the valves to the glue outlet openings and thus onto the work piece by opening the glue valves. Each glue valve comprises at least one tappet comprising a sealing head that is alterable in terms of its position. This sealing head cooperates with a counter element. For this purpose, the sealing head can make sealing contact with the counter element so that glue cannot flow past the sealing head and through the counter element. When the sealing contact is lifted, the glue valve opens and the glue can flow into the glue supply line. An apparatus of this type of construction is disclosed in the patent application DE 103 30 751.
The nozzle unit is often of two-piece construction, the glue outlet openings and glue supply lines being usually inserted into a nozzle plate. The nozzle head often supports the glue valves and the glue chamber.
The disadvantage of arrangements disclosed in the prior art is that prefabricated glue valves are arranged on the nozzle unit. For this purpose, the nozzle unit must be provided with different bores for each valve, which bores can initially guide the glue from the glue chamber to the surface of the nozzle unit, on which the glue valve is disposed, and which then guide the glue from the valve to the glue outlet opening/s in question. The insertion of bores into the nozzle unit is always associated with high costs. Prefabricated glue valves are also expensive.
It is therefore an object of the present invention to provide an apparatus and a method, by means of which costs can be saved.
According to the invention, this object is achieved by the features described herein. Accordingly, provision is made for the counter element of a glue valve to be disposed in or in close vicinity of the glue chamber. For example, the counter element can be disposed in the transition region between the glue chamber and the glue supply line or it can be formed of this transition region. Since the sealing head cooperates with the counter element, the valve can be said to be integrated in the glue chamber. The major advantage of this feature is that it is now possible to completely dispense with the glue lines that bring the glue from the glue chamber to the valves. This considerably reduces the number of bores in the nozzle unit, which consequently cuts costs. There is also no requirement of a separate housing comprising an independent chamber for the valves themselves. As a result of dispensing with the lines guiding the glue, the effort required for the maintenance and, more particularly, the cleaning of the apparatus is also reduced. Moreover, the integration of the valves in the nozzle unit results in a smaller, more compact overall size of the entire nozzle unit.
In an advantageous development of the invention, provision is made for the counter element to be in the form of an independent component and be placed in the transition region between the glue chamber and the glue supply line. This enables the counter element to be replaced easily when, for example, the valve leaks as a result of wear. The counter element can be sealed relative to the glue supply line by means of a sealing component, for example, an O-ring.
It is particularly advantageous if the counter element is cylindrical or discoidal with a thread on its external surface and is screwed into a bore that is provided with an internal thread and is inserted into the glue supply line. This embodiment primarily enables simpler and thus more cost-effective assembly.
It is further advantageous if the counter element is provided with a hexagon socket on one of its ends, preferably on the end oriented toward the glue chamber. The base of this hexagonal recess can provide the locating surface for the sealing head. The opening for the glue can then be provided in the locating surface.
Additional aspects of the invention explained below relate to the tappet. In a related embodiment of the invention, the tappet passes, at least in part, through the glue chamber. This enables a space-saving arrangement of the drive moving the tappet.
In this connection, it is advantageous if the tappet can be displaced by means of an electromagnetic displacement drive. For this purpose, the tappet can comprise magnetic or magnetizable elements that are surrounded by a coil, by means of which a switchable magnetic field can be generated. One major advantage of this feature is that there is no requirement of providing a mechanical connection of the tappet with the space located outside the nozzle unit.
It is of particular advantage if the electromagnetic displacement drive is disposed directly on the glue chamber. Thus the bores required for the electromagnetic displacement drive can be kept short. Moreover, it is also possible to save space in doing so.
A very simple production of the apparatus of the invention is possible if the electromagnetic displacement drive is disposed diametrically relative to the counter element. In this case, the tappet intersects the axis of the glue chamber, if the latter has a round cross section. In the case of a different cross section of the glue chamber, the tappet intersects the axis of the cylinder that can be inscribed in the glue chamber.
Provision is made in an additional advantageous embodiment of the invention for the directions, in which the tappets of two glue valves extend, to be disposed so as to be rotated about the axis of the glue chamber relative to each other. More particularly, when this feature relates to two adjacent valves, these valves can be placed close together in spite of the spatial dimensions of the drives moving the tappets so that the largest possible number of glue outlet openings can be provided per unit length. Two adjacent valves can be rotated by 30 degrees relative to each other, for example.
The nozzle unit can be made, at least in part, of plastic. Firstly, this can simplify production and secondly, this material is cost-effective. Another major advantage is that such a material does not transmit the magnetic field generated by the electromagnetic displacement drive of one valve to an adjacent valve as strongly as is the case in a metallic environment, for example.
Furthermore, the nozzle unit can comprise a plurality of individual segments. A small number of valves can be assigned to such a segment. It is advantageous to assign an individual valve to each segment. It can also be advantageous to assign a plurality of valves to each segment. Thus it is possible to provide as many valves until the arrangement pattern relating to the mutual pivoting of the valves is repeated. For example, if three valves pivot relative to each other and the pivot angle of the fourth valve corresponds to that of the first valve then three valves would have to be provided for each segment. In the case of a segmentation of the nozzle unit, the segments can be produced very cost-effectively since they are each identical. Depending on the desired size of the nozzle unit, only a corresponding number of segments are required to be strung together. Each segment naturally includes a component of the glue chamber, these glue chamber components of the segments being congruent. These glue chamber components can then be in the form of simple cross-holes inside the segments. As a result, a sealing element must be provided between every two segments. The segments can be attached to each other. For this purpose, the segments can be provided, for example, with through-holes, in which threaded rods or other traction mechanisms can be inserted. The individual segments can be pressed against each other by means of these traction mechanisms and corresponding fixing agents such as nuts. The external end faces of the outer segments can each be provided with terminating elements for the glue chamber.
Additional exemplary embodiments of the invention are revealed in the following description and the claims. In the individual figures:
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
Valves 5, 6, 7, by means of which the flow of glue through the associated glue supply lines 3 can be enabled or interrupted, are assigned to each glue outlet opening or also a plurality thereof. For this purpose, each of these valves comprises a tappet 8, 9, 10 that can be moved by drives (not shown in detail) in the directions, in which the tappets extend. Each tappet comprises a sealing head that cooperates with counter elements 11, 12, 13 as described further below.
The individual valves can be arranged so as to be rotated relative to each other. The example of valves 5 and 6 shown in
The counter element 12 is cylindrical or discoidal and it comprises, on its external surface, an external thread 18, by means of which the counter element 12 is screwed into the thread 19 of a bore 20. Advantageously, the diameter of this bore 20 is smaller than that of the bore 21, through which the valve 6 passes. For sealing the counter element 12 relative to the nozzle unit 1, an O-ring 22 can be provided, which is shown in
A coil 23 comprising a guide 24, in which the tappet 9 is guided, is provided as the drive for displacing the tappet 9. An additional guide 25 can also be provided. The guide 24 is sealed relative to the interior of the housing 14, in which the coil is located so that glue cannot flow from the glue chamber 2 or the bore 21 into the interior of the coil.
The invention being thus described, it will be apparent that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be recognized by one skilled in the art are intended to be included within the scope of the following claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4488665 | Cocks et al. | Dec 1984 | A |
| 5875922 | Chastine et al. | Mar 1999 | A |
| 20060160685 | Lamkemeyer | Jul 2006 | A1 |
| 20090107398 | Hassler et al. | Apr 2009 | A1 |
| Number | Date | Country |
|---|---|---|
| 103 27 646 | Mar 2004 | DE |
| 103 09 893 | Apr 2004 | DE |
| 103 30 751 | Feb 2005 | DE |
| 2 055 394 | May 2009 | EP |
| WO 02096570 | Dec 2002 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20110297079 A1 | Dec 2011 | US |
