Patent Publication Number: US-2005139340-A1

Title: Spray system for cleaning wires

Description:
BACKGROUND OF THE INVENTION  
      The present invention concerns a method for cleaning apparatus parts in a binder/glue application apparatus in connection with applying binder/glue on shaped fibre products, where the conveying speed is in the range between 100 m/min and 1000 m/min, where selected apparatus parts are applied an aqueous solution of release agent during operation of the plant and without reduction of capacity, where the release agent solution is applied to the external side of an endless wire.  
      A method of this type is known from U.S. Pat. No. 5,863,385.  
      In connection with application of binder/glue on dry-formed products, it is a well-known problem that loose fibres and binder/glue penetrating through the product is deposited in the mesh of the underlying wire. Application is typically effected with spray nozzles and the underlying wire is often called the spray-wire.  
      When applying binder/glue on a mix of pulp-bicomponent, superabsorber, granulate, superabsorbing fibres and similar air-borne fibres, there have been trouble with keeping spray-wires free from glue and fibre residue. The problem appears particularly at high speeds. Here we are speaking of speeds at 100 m/min and up to above 1000 m/min.  
      At these speeds, difficulty in avoiding penetration of glue is encountered, whereby the wire becomes closed by glue. When the wire is clogged, production has to be stopped for cleaning the wire. This cleaning may often only be performed when the wire is dismounted, which is of course inexpedient with regard to the capacity of the plant.  
      Another problem in connection with such a plant is that pipe systems, ventilators and suction boxes are coated with glue remains that are to be removed regularly mechanically or chemically, which also is to take place during interruption of operation. Such chemical cleaning is often performed by means of solvents and high pressure water.  
      Today, methods for cleaning the wire while being mounted on the machine and during operation are known. This wire cleaning is effected with high pressure water whereby glue and fibre remains are cleaned off the wire. This method has the drawback that the waste water is to go through a cleaning process before it is discharged to the sewerage system, and furthermore the water consumption is very high.  
      A further drawback is that when high pressure water is used during cleaning of a wire, the service life of the wire is influenced dramatically, as the wear on the wire is very great. The limited service life and the time used for changing wire are reasons for daily annoyance and are of course an unsuitable large expense.  
      From U.S. Pat. No. 5,961,735 and U.S. Pat. No. 6,248,213 it is known remove contaminants and excess liquid applied to a felt in a papermaking machine and to conduct it further on to a recycling unit. There is no disclosure of a possible use of the liquid in order to make it easier to remove a depositing on the wire as well as in pipes, suction boxes etc.  
      It is the purpose of the invention to indicate a solution to the above mentioned problems when the wire can be cleaned when mounted and during operation, and where the depositing possibly occurring on wire as well as in pipes, suction box etc. is easy to remove. At the same time, it is the purpose to prolong the service life of a wire by considerably reducing the cleaning wear.  
      By a method according to the invention, behind the application area there is provided a suction slot in which excess release agent solution is collected and conducted further on to a pipe system, a ventilator and a suction box.  
      The method for cleaning a cleaned wire is working by the cleaned wire being moistened at the external side, i.e. the side upon which the shaped product is conveyed, with an aqueous release agent solution. This release agent solution then settles on the wire threads, thus achieving the effect that fibres and excess glue are not adhering so well to the wire.  
      By the mentioned moistening, there will be an excess of the aqueous release agent solution which is not settled on the wire. This excess is collected at the rear side of the wire via a suction slot with associated manifold through which ambient air is sucked. By means of a pipe system and a ventilator the collected and mixed release agent water and air are conducted into the suction box system of the spray-wire. With this supplying of air-release agent mixture, pipe system, ventilator and suction box are coated internally with a release agent film. The atomised and air-mixed release agent thereby acts as a release agent so that dirtying is prevented.  
      A particularly preferred method according to the invention is that where the release agent solution consists of water admixed with release agent, where the mix ratio preferably is 1-10% release agent, and where the said release agent preferably is food certified.  
      Thus is attained a moderate consumption of release agent as well as of water, whereby the total load on the environment becomes as small as possible. The extra advantage connected with using food certified release agent is that the method may be used at the production of dry formed fibre products for application in connection with food products, e.g. packing and napkins. However, it is clear that the method here described also can work with a release agent which is not water-soluble.  
      Furthermore, the method according to the invention concerns that the excess release agent solution collected in the suction slot is admixed with sucked in air to an air-release agent mixture and conducted through pipes and ventilator and further on for distribution on internal surfaces of the suction box via nozzles adapted therefor, whereby the said apparatus parts are continuously coated with a release agent film.  
      Thus is achieved optimal coating of internal surfaces which subsequently provides that only a modest amount of fibres and glue are deposited on the said apparatus parts and surfaces.  
      By the method according to the invention, the release agent solution brought to distribution on the internal surfaces of the suction box via nozzles adapted therefor may communicate with a container and a pump, whereby the said apparatus parts are continuously coated with a release agent film.  
      tinuously coated with a release agent film.  
      With this variant, the amount of release agent supplied to the suction box in relation to the amount applied to the wire may be freely regulated. Hereby is achieved a great flexibility with regard to release agent application when producing different types of items.  
      By a preferred method according to the invention, the wire is cleaned during operation, and subsequently there is continuously applied a solution of release agent where the solution may be aqueous.  
      This cleaning is of a quality far exceeding traditional cleanings of wires of glue and fibre. By this cleaning is thus only used an insignificant amount of water compared with previous methods. The waste water appearing afterwards cannot be discharged to the sewerage system but has to be cleaned before dumping. However, there is the great advantage that, as mentioned, only a negligible amount of water is used compared with earlier times. By traditional cleaning, great inexpediency was prevailing, as up to 40 times more water for cleaning than by the method according to the invention was typically used.  
      However, it is to be noted that the conditions are also improved when binder/glue is applied to the other side of the product after the product having been applied glue/binder at the first side, and has subsequently been subjected to the associated drying.  
      A binder/glue application apparatus for applying binder/glue on shaped fibre products according to the invention is characterised in that said apparatus comprising a number of application nozzles ( 30 ) for applying under pressure an aqueous solution of a release agent to the external side ( 32 ) of the wire ( 12 ) during operation and from there to a pipe system, a ventilator and a suction box, and where behind the application area and in the entire width of the wire there is provided a suction slot in which excess release agent solution is collected and conducted further on via a pipe connection with integrated suction/blowing ventilator to the suction box of the plant as an air-release agent mixture.  
      Thus is achieved an optimal utilisation of the aqueous release agent mixture which by the collection is admixed with an amount of air and in this way is brought in contact with various machine parts. These machine parts to which the air-admixed release agent comes into contact is thus provided a desired coating with dirt-repelling effect.  
      A binder/glue application apparatus according to the invention is by the suction box made with distributing means for regular distribution of the air-release agent mixture at the internal surfaces of the suction box, where the distribution means are preferably disposed immediately under the wire at the end faces of the suction box transversely of the wire, where the air contains release agent, and where the distribution means are communicating with a pipe system from the suction slot.  
      With this distribution means is ensured even distribution of the air-release agent mixture, whereby extended operation time between cleaning of suction box, pipe system and ventilator can be maintained.  
      A binder/glue application apparatus can be designed so that the suction box is made with distributing means for regular distribution of a release agent mixture at the internal surfaces of the suction box, where the distribution means preferably are disposed immediately under the wire at the end faces of the suction box tansversely of the wire, where the distributing means communicates with a container and a pump.  
      The amount of release agent supplied to the suction box in relation to the amount applied to the wire may thus possibly be regulated. With this possibility is achieved great flexibility with regard to regulating release agent application under various operation conditions.  
      In a variant of the said binder/glue-application apparatus there may additionally be provided with at least one distributing means in the suction box, where the said further distributing means is disposed immediately under the wire and transversely of the wire between the end faces of the suction box.  
      In this way, a suction box and its internal elements may be applied a release agent surface if necessary.  
      A binder/glue application apparatus according to the invention is typically designed so that the wire is running through a cleaning station prior to passing the application station for the release agent mixture.  
      Hereby is achieved the advantage that the wire is always clean prior to application of release agent so that a layer of fibres and glue is not built up upon which is only applied a further layer of release agent.  
      In a variant of the invention, the binder/glue application apparatus may be designed so that the wire is an independent endless wire that is only used in the binder/glue application process. Alternatively, the wire, besides being used at the application of binder/glue, may also be used by one or more preceding and/or succeeding processes, e.g. at a heat treatment.  
      With the above solution, machines can run with higher production speeds and with minimal operation interruptions and with strongly reduced wire cleaning problems. Improved work environment and reduced waste water expenses are, as previously mentioned, also advantages that may be emphasised. 
    
    
     DESCRIPTION OF THE DRAWING  
      In the following, the invention is described with reference to the drawing which, without being limiting, shows a preferred embodiment of a binder/glue application apparatus according to the invention, where:  
       FIG. 1  shows a binder/glue application apparatus with independent wire.  
       FIG. 2  shows a binder/glue application apparatus where the wire is running through a drying station. 
    
    
      On  FIG. 1  appears a binder/glue application apparatus  2  in a preferred embodiment of the invention. The apparatus  2  applies binder/glue  4  to shaped fibre products  6  that are conveyed under application nozzles  8  and air nozzles  10  via a so-called spray-wire  12  (Oust called wire in the following). This wire  12  is passed via roller  14  around a suction box  16  which by means of vacuum from a vacuum pump  18  retains the fibre product  6  and ensures an optimal penetration of binder/glue  4 .  
      At the feeding end  20 , immediately before the wire  12  is brought into contact with the fibre product  6 , there is an application station  22  for release agent spray  24 . This application station  22  consists of a container  26  in which release agent and water are mixed and are pumped from there with a pump  28  to a number of application nozzles  30  for the aqueous release agent solution  24 . This application occurs at the external side  32  of the wire, and behind the wire  12  at the application station  22  there is disposed a so-called suction slot  34  in which release agent water  24  and ambient air are sucked up and brought into distribution means  40  in the suction box  16  by means of a suction/blower ventilator  36  in a pipe system  38 . These distribution means  40  are provided with a number of nozzles  42  and are moreover disposed at the end faces  44  of the suction box. Through these distribution means  40 , the release agent air  52  is now distributed over the internal surfaces  46  in the suction box  16  with the distribution nozzles  42  so that glue and fibres are not deposited.  
      Immediately in front of the application station  22  for release agent there is disposed a cleaning station  48  performing a cleaning of the wire  12 . When the product  6  is leaving this binder/glue application apparatus  2 , it is conveyed further on to the next process, here a drying station  50 , after which it  6  possibly returns for application of binder/glue  4  at the other side.  
       FIG. 2  shows a second preferred embodiment of the invention which in its simplicity is acting in the same way as in  FIG. 1 , however with the difference that the wire  12  is this variant continues further through the next process apparatus  50 , here a drying station. Furthermore, in the shown suction box  16  there is provided a third distributing means  40  with distribution nozzles  42  at both long sides. On this variant of the apparatus also there is disposed a wire cleaning station  48  preceding the application station  22  for the release agent solution  24 .