METHOD FOR PROTECTING AN ADHESIVE DELIVERY APPARATUS, AND THIS SAME

Abstract

A method for protecting an adhesive delivery apparatus (10) having an adhesive outlet opening (16) through which adhesive can be extracted from the adhesive delivery apparatus (10), in particular toward a surface (13) which is to be wetted with the adhesive, which comprises feeding of an air moisture protection gas (41) into the region of the adhesive outlet opening (16), is described and represented.

Claims

1. A method for protecting an adhesive delivery apparatus having an adhesive outlet opening through which adhesive is extracted from the adhesive delivery apparatus toward a surface (13) which is to be wetted with the adhesive, which comprises feeding an air moisture protection gas into a region of the adhesive outlet opening.

2. The method as claimed in claim 1, wherein an adhesive delivery apparatus for adhesive of a type which hardens under the addition of air moisture is protected, the adhesive being a polyurethane and/or hot-melt and/or reactive adhesive.

3. The method as claimed in claim 1, wherein the adhesive delivery apparatus is configured as a spraying apparatus for the spraying delivery of the adhesive as a filament, through the use of a spraying medium, the air moisture protection gas being employed as the spraying medium.

4. The method as claimed in claim 1, wherein a dry gas is used as the moisture protection gas.

5. The method as claimed in claim 4, wherein the dry gas passes through a membrane dryer connected upstream thereof, before being used as the moisture protection gas.

6. The method as claimed in claim 1, wherein the moisture protection gas is fed to the region of the adhesive outlet opening when no adhesive is extracted from the adhesive delivery apparatus, such as during a pause in production.

7. The method as claimed in claim 1, wherein the inflow rate of air moisture protection gas into the region of the adhesive outlet opening is switchable and can be throttled, when no adhesive is extracted from the adhesive delivery apparatus, such as during a pause in production.

8. The method as claimed in claim 1, wherein the air moisture protection gas is conducted at an angular offset to a principal direction of delivery of the adhesive, which direction is defined by an orientation of the adhesive outlet opening, into the region of the adhesive outlet opening.

9. The method as claimed in claim 1, wherein the moisture protection gas is conducted into a region of the adhesive outlet opening from at least two directions, forming a dry protective gas curtain around the adhesive outlet opening.

10. An adhesive delivery apparatus, comprising: an adhesive outlet opening through which adhesive is extracted from the delivery apparatus toward a surface which is to be wetted with the adhesive; and a moisture protection gas feed line for feeding a moisture protection gas into a region of the adhesive outlet opening.

11. The method as claimed in claim 4, wherein the dry gas is dried air.

12. The method as claimed in claim 4, wherein the dry gas is a dried inert gas.

13. The method as claimed in claim 4, including a membrane drier.

14. The method as claimed in claim 13, including a filter.

15. The method as claimed in claim 14, wherein the filter is positioned upstream of the membrane drier.

16. The adhesive delivery apparatus of claim 10, further including a gas drier.

17. The adhesive delivery apparatus of claim 16, wherein the gas drier is a membrane drier.

18. The adhesive delivery apparatus of claim 16, further including a filter, wherein the filter is upstream of the gas drier.

Description

[0060] Further advantages and embodiments of the invention emerge from the non-cited subclaims and from the now following description of the figures, in which:

[0061] FIG. 1 shows in a very schematic, non-true-to-size basic representation a schematic side view of an apparatus according to the invention, with implementation of the method according to the invention, said apparatus having, by way of example, four adhesive delivery nozzles, wherein these are assigned to a robot arm and wherein these are connected for supply purposes to a membrane air dryer, which, for the sake of clarity, is shown in strongly enlarged representation, and wherein the gas is not represented,

[0062] FIG. 2 shows a very schematic, partially sectioned side view of a delivery module of the delivery apparatus according to the invention, roughly along the view arrow II in FIG. 1,

[0063] FIG. 3 shows a very schematic bottom view for representing the adhesive outlet openings and the spraying medium outlet openings of the nozzle head represented in FIG. 1, approximately in a bottom view according to the view arrow III in FIG. 1, wherein FIG. 3 explicitly shows only one detail,

[0064] FIG. 4 shows a very schematic sectional view through the nozzle head represented in FIG. 1, with representation of the respective adhesive outlet openings and of the spraying medium outlet openings, wherein in FIG. 4, by way of example, the velocity ranges of the emerging spraying medium are provided with different hatchings or markings, and

[0065] FIG. 5 shows in a likewise very schematic sectional view, roughly according to the view arrow V in FIG. 4, a cross section through one of the there represented nozzles of the nozzle head, with the same type of representation of the spraying medium velocities.

[0066] As a preface to the following description of the figures, it should be stated that same or comparable parts are provided, where appropriate, with identical reference symbols, sometimes with the addition of small letters or apostrophes as a suffix. In the patent claims which follow the description of the figures, the reference symbols employed in the figures and in the description of the figures may therefore (sometimes) be employed, for the sake of simplicity, without apostrophes or small letters, insofar as the corresponding objects are comparable.

[0067] FIG. 1 shows firstly an adhesive delivery apparatus 10 according to the invention in a very schematic side view, wherein the size relationships have been adapted or altered for the sake of clarity.

[0068] The represented adhesive delivery apparatus 10 here comprises an application head 11, which is guided over a surface 13, which is to be provided with adhesive 12, of a workpiece 14, for instance in the transport direction F, i.e., in respect of FIG. 1, into the plane of the figure.

[0069] The workpiece 14 can be constituted, for instance, by a workpiece of the automotive industry, for instance a body part of an automobile, or similar. The adhesive 12 is here applied substantially over the whole of the surface 13, in particular with the aid of spraying medium, which likewise emerges from the application head 11, but is not represented in FIG. 1. In the represented illustrative embodiment, this spraying medium causes the four exemplary adhesive filaments to have a substantially (in the plane) meandering shape.

[0070] The four adhesive filaments are here delivered from four exemplary nozzles 15a, 15b, 15c, 15d of the application head 11, for which purpose these in particular respectively have an adhesive outlet opening 16 (merely indicated in FIG. 1). In principle, each nozzle 15 can alternatively, however, also have, of course, a plurality of adhesive outlet openings 16.

[0071] The discharged adhesive 12 can typically be constituted by a so-called hot-melt adhesive, which in particular can have a polyurethane base, and in particular, as a result of a reaction with the air moisture of the atmospheric air 42 surrounding the workpiece 14, can react and harden. Before or at the same time, a further counter workpiece is typically, however, assigned to the workpiece 14 or the surface 13 and bonded thereto.

[0072] In the represented illustrative embodiment, the application head 11 is moved over the surface 13 in the transport direction F by a holding device 17, which in the illustrative embodiment is configured as a robot arm. This should be construed as merely illustrative. In principle, the holding device could also be configured as a stationary holding device, such as a bridge or similar, and the workpiece 14 could be guided along the application head 11 (for example with the aid of a conveyor belt).

[0073] In said illustrative embodiment according to FIG. 1, the application head 11 is connected via a connection (not represented) to a control device 18. The latter can be assigned, for instance, to the holding device 17, wherein the control device 18 can regulate the controlling of the application head 11, for example the opening times of the nozzles, the desired outlet quantities of adhesive, and similar. In principle, the control device 18 can however also be utilized to control the relative movement between surface 13 and application head 11, for instance by controlling the holding device 17 and/or a conveyor for the workpiece 14.

[0074] In the illustrative embodiment, the positioning of the control device 18 should likewise be construed as merely illustrative. In principle, the control device 18 could also be arranged further remote from the application head 11 and be configured, for instance, as a stationary computer, which, via a wireless or wired connection, can transmit information to the application head 11 and/or the holding device 17.

[0075] Moreover, the application head 11 is connected via a gas line 19, which can be constituted, for instance, by a hose or similar, to an air dryer 20. The running of the gas line 19 should here be construed as merely schematic. In practice, the line 19 would actually more likely be laid on the mounting 17 along to the head 11.

[0076] The air dryer 20 herein substantially comprises (viewed in the direction of flow) an inlet valve 21, a first filter 22, a second filter 23, a membrane dryer 24, a regulating element 25 and a connector 26.

[0077] The inlet valve 21 here has, for instance, a connector 27, by means of which the air dryer 20 can be connected in a non-represented manner to a standard compressed air connection. In this way, compressed air can thus make its way into the air dryer 20. This compressed air can in the first filter 22 firstly be cleaned of coarse impurities, such as, for instance, dirt particles or oil particles.

[0078] A finer filtering of the compressed air can subsequently take place in the second filter 23, which typically has a still finer filter element. The actual drying of the compressed air then takes place in the membrane air dryer element 24, which comprises the actual membrane. This membrane here consists of a large number of hollow fibers lying parallel to one another in the longitudinal direction, which in FIG. 1, however, are not represented, but are arranged within the element 24. Moisture can easily pass through these hollow fibers, yet the remaining compressed air components cannot readily do so. The moisture of the compressed air is here induced according to known principles to pass through the filter and can then leave the element 24 at a moisture or water connection 28 in a manner which is not represented in detail.

[0079] The dried air or dry air can then make its way in the direction of flow R through a regulating element 25 (with which, for instance, a stopcock-like turn-off can be realized) into the connector 26, which in the present illustrative embodiment is configured, for instance, as a T-piece. While the lower T-piece outlet is provided with a plug 29 (for potential further connections), to the upper outlet of the T-piece 26 is connected the aforementioned gas line 19.

[0080] Advantageously, between the air dryer 20 and the application head 11 is arranged a further valve 30, which in particular is configured as a proportional valve. This can adjust the transmission of dried air, for instance between at least two different flow rates. This proportional valve 30 too can preferably be connected to the control device 18.

[0081] In summary, in respect of FIG. 1, it can thus be established that, via the line 19 in the air dryer 20, dried, previously conventional, compressed air (in particular in two different states due to the valve 30) can be conducted to the application head 11.

[0082] This application head 11 is in FIG. 2 represented in a partially sectioned, very schematic side view, which substantially corresponds to the view arrow II in FIG. 1.

[0083] In FIG. 2, firstly no meandering of the discharged adhesive filament 12 is discernible, so that that meandering characteristic of the filaments 12 which is represented in FIG. 1 extends principally onto a plane running transversely to the actual transport direction F.

[0084] It can further be seen from the view according to FIG. 2 that the application head 11, in the plane represented, is constructed such that it is substantially divided into three parts: Thus, to the adhesive outlet 16 is firstly assigned a discharge nozzle 15 (left-hand region in respect of FIG. 2), while in the lower region is connected an air or gas block 31, above which an adhesive block 32 is in this case provided.

[0085] The gas block 31 firstly has a gas connector 33, via which the dried compressed air which is fed to the application head 11 via the line 19 can make its way into the gas block 31. In order to heat the dry air or keep it warm, in the gas block 31 is provided a heating unit 34, which is supplied with current via an electrical connection 35. It is here important to keep the gas 41 warm or heat it, since the adhesive in question is a hot-melt adhesive, which, when entering into contact with the gas (typically outside the adhesive outlet 16), must not be allowed to abruptly cool. The dry air 41 can hereupon make its way via the dashed path, for instance, into the region 36 of the nozzle 15 and can there be discharged via a separate opening (not shown in FIG. 2 due to the sectional representation) and fed to the region 36 of the adhesive outlet opening 16.

[0086] The adhesive block 32 then likewise provides an electrical connection 35 for a heating element (not specifically labeled) in the adhesive block 32, whereby the hot-melt adhesive, of course, shall be kept warm. In addition, an (exchangeable) filter element 37 for the hot-melt adhesive is provided, and, of course, an adhesive connector 38, by which the adhesive (which is advanced to the application head 11 in a manner not represented in detail, for instance with the aid of a line or similar,) is connected up to the adhesive block 32.

[0087] The adhesive 12 can then run through the adhesive block 32 along the dashed path and so make its way to the nozzle 15 or the adhesive outlet 16 and emerges there under pressure.

[0088] If the adhesive 12 passes out of the adhesive outlet 16, it is carried by the dried compressed air 41, which is employed as a spraying fluid, onto the surface 13 represented in FIG. 1.

[0089] In order that that meandering shape of the adhesive filaments which is evident in FIG. 1 can be formed, to each adhesive outlet opening 16 can be assigned, in particular, a plurality of, namely in the present illustrative embodiment two, protective gas outlet openings 39. This is illustrated by FIG. 3.

[0090] FIG. 3 here represents a segmental, linear bottom view of the application head 11, in particular in relation to the four adhesive outlets 16 of the application head 11. The application head 11 can here be of four-part configuration and consist of four modules which are arranged side by side in the longitudinal direction L and which respectively have a cross section as represented in FIG. 2.

[0091] Thus each of these modules here has, according to FIG. 3, a central adhesive outlet 16 and two flanking protective gas outlet openings 39. Because two protective gas outlet openings 39 are assigned to the adhesive outlet 16 substantially symmetrically, the alternating filament is able to be achieved. In this case, the filament shape generally adjusts itself automatically, since typically an air blast firstly deflects the filament on one side and, by virtue of the two lateral air outlets, a steady state or a swinging back and forth is then achieved.

[0092] The two protective gas outlet openings 39 assigned to an adhesive outlet 16 can herein be assigned feed lines 40, which are arranged at an angle a to the principal direction of delivery H of the adhesive. The angle a is, in particular, an acute angle, which preferably measures between 10 and 25 degrees.

[0093] This is evident in FIG. 4, wherein FIG. 4 represents a very schematic, enlarged sectional representation of the lower part, comprising the adhesive outlets 16, of the application head 11 (in a frontal view roughly according to FIG. 1).

[0094] In other words, the dried compressed air can pass (in a straight line) out of its protective gas outlet opening 39 at an angle of intersection a to the pass-out direction H of the adhesive (from the adhesive outlet 16). To put it another way: the direct feed lines 40 of the protective gas to the protection outlet openings 39 are arranged and oriented (preferably in opposite directions) at an angle relative to the (central) direct adhesive feed line 43 to the adhesive outlet opening 16.

[0095] FIG. 4 illustrates (the adhesive having been omitted) the predominant velocities of the protective gas 41 in the region of a nozzle outlet or in the region of the adhesive outlet 16: Thus, the compressed air velocity ranges are provided with different hatchings or markings. Here, the faster is the flow velocity in this region, the denser is the hatching or marking.

[0096] For instance, it can here be seen that the velocity of the protective gas 41 is highest in the region of the feed lines 40. As soon as the gas makes its way through the protective gas outlet opening 39 into the open, the velocities naturally diminish and basically decrease in all directions with remoteness from the outlets 16, 39.

[0097] It is herein of critical importance, however, that the protective gas 41, i.e. the dried compressed air, for instance, forms in the region 36 of an adhesive outlet 16 a curtain, a hood or a blanket or similar, which isolates the adhesive outlet 16 from the moisture of the ambient atmosphere or ambient air 42.

[0098] This curtain or hood function is illustrated by the view according to FIG. 5, which shows a section through the application head 11 according to the section line V-V in FIG. 4. According to the view of FIG. 5, it herein becomes clear that the adhesive outlet, which cannot be seen in FIG. 5, is also sufficiently securely laterally isolated, namely by the protective gas 41, from the ambient air 42.

[0099] Because the protective gas 41 itself has virtually no significant air moisture, it is thus possible to ensure in total that no moist air can make its way to the adhesive outlet 16. Any adhesive remaining in the adhesive outlet 16 is thus protected from moisture and will not react or harden, so that the adhesive outlet 16 as a whole remains clear.

[0100] In respect of FIG. 4, it should finally be pointed out that, in the present illustrative embodiment, four nozzles 15 having respectively an adhesive outlet 16 are represented by way of example. In principle, however, a plurality of nozzles or more than four nozzles, or more than four modules, can of course be employed to form an application head 11. In FIG. 4, but also, for instance, in FIG. 1 or 3, the corresponding components are therefore not universally provided with separate reference symbols. The reference symbols should also however be readily transferable to the parallel nozzles.

[0101] Regarding the method according to the invention which is represented in the figures, it should basically be noted that the discharged protective gas 41 represented in FIGS. 4 and 5 is in the illustrative embodiments employed as spraying medium. In the illustrative embodiment, the protective gas 41 is accordingly transported and extracted from the openings 39 both during a production process (i.e. during the discharging of adhesive 12) and during a production stoppage or shutdown. Such a phase is here shown, for instance, by FIGS. 4 and 5, in which, therefore, no transported adhesive, but only an adhesive residue 44, is represented.

[0102] During such a pause in production or such a production stoppage, protective gas 41 thus continues to pass out of the application head 11.

[0103] In this context, in a method according to the invention, the discharge rate or throughput of protective gas 41 can, however, be throttled. The ulterior motive is here that gas 41 can be saved in those phases in which it is not required as a carrier medium. In these phases, fundamentally less gas 41 is needed to maintain the protection function for the adhesive outlets 16 which is represented in FIGS. 4 and 5.

[0104] If the production is then resumed, the throttling can be withdrawn and more protective gas 41 can again be transported and emitted via the openings 39, namely in such magnitude that the carrier medium characteristic of the gas 41 is fulfilled, as is expressed, for instance, in the adhesive filaments 12 represented in FIG. 1.

[0105] For this, as shown in FIG. 1, for instance, the aforementioned proportional valve 30 can be employed. The latter can ensure, in particular via an actuation by the control device 18, that the gas outlet into the region 36 of an adhesive outlet 16 (or of all adhesive outlets 16) is reduced for the phases in which a pause in production obtains.

[0106] It can be established, however, that in the illustrative embodiment air moisture protection gas is basically always introduced into the region of the adhesive outlet opening 16 or is fed thereto, regardless of whether production is just taking place and whether adhesive is being applied or not.