Patent Publication Number: US-11643780-B2

Title: Blowing equipment for doctor equipment of a fiber web machine and fiber web machine doctor equipment equipped with blowing equipment

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application claims priority on Finnish App. No. 20205930, filed Sep. 25, 2020, the disclosure of which is incorporated by reference herein. 
     STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The invention relates to blowing equipment for doctor equipment of a fiber web machine, which blowing equipment includes a distribution channel, the length of which corresponds essentially to the length of the doctor equipment, and nozzle devices for directing blowing in the doctor equipment, and the nozzle devices are arranged to be adapted to a blade holder belonging to the doctor equipment for establishing doctor blowing. The invention also relates to doctor equipment of a fiber web machine, where the doctor equipment is equipped with blowing equipment. 
       FIG.  5    shows an example of the location of blowing equipment in a fiber web machine, such as in a paper, board, and tissue machine. Doctor blowing is established with the blowing equipment. The blowing equipment is adapted in the doctor equipment  40 , which is located on the last drying cylinder  46  of a cylinder drying group. At this point, the fiber web is run down into a pulper  42 . Doctor blowing is used for ensuring that the fiber web W comes off from the surface of the drying cylinder  46 . There are also other critical positions even elsewhere in the fiber web machine, such as when the grammage of the fiber web increases after coating and the features of the fiber web change. Blowing equipment is especially necessary when a certain grammage is exceeded at a certain speed. As an example, a light-weight fiber web with a grammage of less than 100 grams still comes off at a speed of 1300 meters per minute without doctor blowing, while a fiber web of more than 200 grams requires doctor blowing at a speed of as low as 1000 meters per minute. The design limits may vary depending on a specific machine and fiber product. A single fiber web machine may have about 10 doctor equipment equipped with blowing equipment. 
     Prior art blowing equipment includes an air pipe that forms a distribution channel, which air pipe is fastened to a beam that supports the doctor equipment, beneath the beam. The air pipe extends essentially across the entire length of the doctor equipment. Nozzle devices have correspondingly been arranged in a blade holder at a distance from one another to establish doctor blowing. There is a separate distribution pipe for each nozzle device. In other words, there is a separate distribution pipe from the air pipe to each nozzle device. Air is supplied into the air pipe and from it to the nozzle devices via distribution pipes. 
     The air pipe and the distribution pipes require much installation space. Moreover, the air pipe and the distribution pipes are susceptible to breakage, and they gather loose material easily on their surface. The entire doctor beam has to be removed for the maintenance of the blowing equipment and for the adjustment of the nozzle devices, and this requires the stopping of production. On the other hand, the utilization of the blowing equipment in itself requires a doctor beam. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to accomplish a novel kind of blowing equipment for the doctor equipment of a fiber web machine, which blowing equipment is more compact and efficient than before, but of a lighter weight and simpler than before. The characteristic feature of the blowing equipment according to this invention is a distribution channel adapted to be fastened to a blade holder. Another object of the present invention is to accomplish a novel kind of doctor equipment of a fiber web machine, where the doctor equipment is equipped with blowing equipment, which doctor equipment is easier to use and of a lower cost than before and also quicker to adjust and maintain than before. The one characteristic feature of the doctor equipment according to the invention is that a distribution channel is fastened to the blade holder. In the blowing equipment according to the invention, the distribution channel is implemented in a novel and surprising manner. In this way, the structure of the blowing equipment can be made compact. At the same time, doctor blowing can be added easily to existing doctor equipment. 
     Moreover, the doctor blowing can be maintained and adjusted even during production. Furthermore, the doctor blowing can be implemented into various types of doctor equipment, and the blowing equipment itself contains few components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described below in drawings that illustrate an embodiment of the invention. 
         FIG.  1    shows doctor equipment equipped with blowing equipment according to the invention viewed from an end. 
         FIG.  2   a    shows a distribution channel according to the invention viewed from above. 
         FIG.  2   b    shows an end section of the distribution channel of  FIG.  2   a    in a fragmentary axonometric view. 
         FIG.  3    shows the blowing equipment according to the invention viewed from above. 
         FIG.  4   a    shows the blowing equipment according to the invention viewed from a first direction of an intermediate structure of the distribution channel. 
         FIG.  4   b    shows the intermediate structure of  FIG.  4   a    from a second direction. 
         FIG.  5    shows an example position for the doctor equipment according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG.  1    shows blowing equipment according to the invention, which blowing equipment is primarily intended for doctor equipment of a fiber web machine. The doctor equipment can include at least the doctor blade and the doctor blade holder. The doctor equipment is used for ensuring that the fiber web produced comes off a roll, drying cylinder or equivalent surface, as shown in principle in  FIG.  5   . At the same time, the doctor equipment is used for removing material from the surface doctored e.g. the roll surface, and for maintaining the surface roughness of the surface doctored. A doctor blow is also arranged as part of the doctor equipment primarily so as to ensure that the fiber web comes off the roll surface, which is doctored. The doctor blow opens so as to blow air in the machine direction toward the surface doctored. The doctor blade extends along the full width in the cross machine direction of the of the surface in the fiber web machine which is doctored, in other words in the longitudinal direction of the doctor equipment. The doctor blow is directed to the front side i.e., the side facing the doctored web, of the doctor blade, so that the doctor blow makes the fiber web come off before the doctor blade, which can hence remove material in an undisturbed manner from the surface doctored. The blowing equipment  10  includes a distribution channel  11 , the length of which corresponds essentially to the length of the doctor equipment, and nozzle devices  12  for directing blowing air in the doctor equipment. The nozzle devices  12  are arranged to be adapted to a blade holder that belongs to the doctor equipment, for establishing doctor blowing. In this way, the blowing that opens from the nozzle devices is advantageously directed precisely to the point where the fiber web comes off. According to the invention, a distribution channel  11  is adapted to be fastened to the blade holder  13 . In this case, separate distribution pipes are unnecessary, and the blowing equipment can be adapted to many kinds of doctor equipment. At the same time, the size and mass of the blowing equipment are reduced, whereby separate beams can be omitted, which further reduces the costs. Structures that are susceptible to breakage and fouling are also omitted. 
     In accordance with  FIG.  1   , the distribution channel  11  has a wedge-like cross section, e. g. narrows on a side closest the nozzle devices  12 . In this way, the accumulation of material on top of the blowing equipment is avoided. At the same time, the progress of the fiber web remains undisturbed, for example, when running down the fiber web ( FIG.  5   ). The distribution channel  11  is advantageously an extruded metal piece which defines a frame  41 , which is adapted to extend essentially across the entire length of the blade holder  13 . By means of extrusion, the distribution channel  11  can be easily given the desired shape, and at the same time the distribution channel can be made uniform across the entire length needed. On the other hand, the distribution channel  11  can be formed, for example, from two parts that are joined together at their ends. Air is advantageously supplied from both ends of the distribution channel  11 , in which case the air flow is distributed as evenly as possible. When manufactured from two or more parts, the blowing equipment can be transported easily to the place of use. At the same time, the manufacture and machining of the distribution channel are facilitated. 
     The metal piece frame  41  is most suitably of aluminum, which is well applicable to extrusion. Moreover, aluminum is of light weight and easily machinable. Aluminum can also withstand the harsh conditions of a fiber web machine even without surface treatment. However, a Polytetrafluoroethylene (PTFE) coating is advantageously used. This protects aluminum against corrosion and facilitates it staying clean and its cleaning. 
     The blowing equipment according to the invention is compact. The wedge-like shape alone accomplishes a flat structure. At the same time, the distribution channel  11  frame  41  can be given a sufficient cross-sectional area of the flow, whereby the doctor blowing can be made sufficiently efficient. Moreover, the nozzle devices  12  are advantageously integrated into the distribution channel  11 . In this way, separate distribution pipes are unnecessary, and the mass of the blowing equipment remains small. More specifically, the nozzle devices  12 , as shown in  FIG.  2   b   , are formed from several nozzle openings  14  that have been machined in the distribution channel  11  frame  41  at a distance from one another. After extrusion, the distribution channel  11  is complete in terms of its external shape and internal flow channel  42  which is defined by the internal shape of the distribution channel, whereby the nozzle openings can be machined easily in the aluminum piece. The frame  41  has an inner wall  45  within the flow channel  42  and an outer wall  44  external to the flow channel. At the same time, an independent adjustment plate  15  can be adapted in a nozzle opening  14 . Each adjustment plate  15 , as shown in  FIG.  3   , is fixed to the distribution channel frame  41  to overly a nozzle opening  14  allowing the air blow to escape from the nozzle device  12  between the adjustment plate  15  and the distribution channel frame. In this case, the flow characteristics of each nozzle device  12  formed by the nozzle opening  14  and the plate  15  can be adapted to be those desired. In other words, the distribution channel  11  includes adjustable nozzle elements  15  in the nozzle devices  12 .  FIG.  3    shows one adjustment plate  15  separate from the blowing equipment  10 . As an example, a more intense doctor blowing can be directed, if necessary, to the edges of the fiber web than to the center part, by adjusting the nozzle devices. In this way, it can be ensured that the fiber web comes off. In machining, material is removed from the extruded piece frame  41  forming the distribution channel  11 . Advantageously at the location of the nozzle opening  14 , there is a recess  16  in the distribution channel  11  as shown in  FIG.  2   b    which matches and receives the adjustment plate  15 . In this case, the mass of the extrusion forming the distribution channel  11  is reduced further, and at the same time a suitable space is obtained for the adjustment plate  15 . In this way, the amount of loose material collected by the adjustment plate is small, and the adjustment plate remains in the correct position, whereby the nozzle gap  43  remains straight. In the application presented, the adjustment plate  15  has two oval holes  17 , which enable the moving of the adjustment plate and hence the adjustment of the nozzle gap  43  by loosening or tightening the fastening screws  18 , with which the adjustment plate  15  is fastened to the distribution channel  11 . There are threaded holes  18 ′ in the distribution channel for the fastening screws. By means of the adjustment possibility, doctor blowing can be easily profiled over the length of the doctor equipment, in other words in the cross machine direction of the fiber web machine, and at the same time it is also possible to optimize the need for air supply. Air is advantageously supplied from both ends of the distribution channel, whereby air is distributed evenly across the entire distance of the doctor equipment. In this way, by adjusting the nozzle gaps  43 , the air flow and mass flow and hence the doctor blowing can be adjusted as desired. 
     The nozzle devices form a simple nozzle gap  43 , the size of which can be adjusted by the adjustment plate  15  as shown in  FIG.  3   . In  FIGS.  2   a  and  2   b   , the structure of the distribution channel is presented before the installation of the adjustment plates  15  into place. The adjustment plates  15  and oval holes  17  are so dimensioned that even with the smallest adjustment, there is always a gap  43  that ensures doctor blowing across the entire width of the doctor equipment. In the application presented, the nozzle opening  14  has a shaping  19  of the frame  41  outer wall  44 , where there is a narrowing  21  of the nozzle opening  14  in the flow direction. In this case, it is possible to increase the flow velocity of the air supplied from the distribution channel into the nozzle opening  14 , which intensifies blowing. Hence, even a heavy fiber web is sure to come off from the surface of a drying cylinder, for example. At the same time, the air supply is sufficient. 
     In accordance with  FIG.  3   , the distribution channel  11  includes an end piece  22 , which has a connection  23  for an air hose  24  or equivalent. In this case, it is possible to easily fasten a normal hose  24  or other channel even to the wedge-like distribution channel  11  for the supply of air. For the positioning of the end piece  22 , there is a bevel  25  at the end of the distribution channel  11 , in which case the end piece settles tightly into place. The end piece  22  can be of plastic, for example. 
     The lower part of  FIG.  3    shows a special solution, which ensures tail threading that is used at the beginning of the manufacture of the fiber web. In tail threading, a narrow strip of the fiber web is taken through the fiber web machine, after which the tail threading strip is spread to a full-width fiber web. In accordance with  FIG.  3   , there is an intermediate structure  26  at one end of the distribution channel  11  bordering and forming an auxiliary channel  27 . The auxiliary channel  27  is also shown in  FIG.  1   . Moreover, the auxiliary channel  27  includes an air supply connection  28  of its own for the establishment of an adjusted flow, such as edge blowing. With the solution presented, a really efficient doctor blowing is accomplished in the tail threading area, which doctor blowing makes the tail threading strip come off and guides it to the desired direction. In this way, tail threading succeeds at once, which shortens production interruptions. In other words, the starting of production is quick. During tail threading, the full-width doctor blowing is switched off, whereby, if necessary, the entire air flow can be directed to the tail threading area connected to the auxiliary channel  27 . The intermediate structure  26  that is illustrated with a thick broken line here extends over the distance of six nozzle openings. The intermediate  26  structure is shaped in accordance with the flow channel, and moreover, an end guide  29  and the end piece  22  together with the intermediate structure  26  seal a separate channel in the tail threading area. The air connection  23  and the air supply connection  28  are advantageously adapted in the same end piece  22 . 
     The intermediate structure  26  is also shown in  FIG.  1   , where it is fastened to the distribution channel  11  by means of a screw  30 . In  FIGS.  4   a  and  4   b   , the intermediate structure  26  is shown from two different directions. The screws  30  used for fastening here are already in the intermediate structure  26 . 
     The structure of the blowing equipment becomes even simpler especially by utilizing a shaped nozzle opening  14 . The blowing equipment advantageously includes a compressor  31 , the output of which is limited to 5-10 bar. In this case, even a simple pressure-generating device accomplishes a sufficient air flow for the establishment of efficient doctor blowing. At the same time, the blowing equipment can be adapted even in existing doctor equipment, in which case the doctor blowing can be added, if necessary, quickly and easily in a fiber web machine. 
       FIG.  1    shows the doctor equipment  40  of a fiber web machine, where the doctor equipment is equipped with blowing equipment. Here, the doctor equipment includes a blade holder  13  for a doctor blade  33 . The holder  13  comprises an upper jaw and a lower jaw  32 , between which the doctor blade  33  is placeable. The upper jaw can be a uniform part of the holder  13  or, like in  FIG.  1   , it can be composed of a separate press plate  38 . The blade holder  13  can be of fiber-reinforced plastic composite or, for example, of aluminum, such as in this application. Moreover, the blowing equipment  10  includes a distribution channel  11  as well as nozzle devices  12  fastened to the blade holder  13  for the distribution of air in the doctor equipment and hence for directing blowing in the doctor equipment. According to the invention, the distribution channel  11  is fastened to the blade holder  13 . In  FIG.  1   , the distribution channel  11  is screwed to the blade holder  13 , in which case, in operating condition, the entire blowing equipment that comprises both the nozzle devices and the distribution channel is tightly fastened to the blade holder. In this case, the doctor blowing opens in the direction of the doctor blade, hitting the surface doctored before the doctor blade. The application presented utilizes the frontmost screws  39  of the press plate  38 , with which screws  39  both the press plate  38  and the distribution channel  11  are fastened to the blade holder  13 . In this case, the blowing equipment can be adapted to the doctor equipment without changing the structure of the doctor equipment. The openings  20  for the screws are illustrated in  FIGS.  2   a    and  2   b.    
     Irrespective of the doctor equipment, the above-described blowing equipment is used. A significant additional advantage is achieved when a certain type of doctor equipment is used. Advantageously for supporting the blade holder  13 , the doctor equipment  40  includes a body piece  34 , and there is a form-locking hinge  35  between the blade holder  13  and the body piece  34 , which hinge  35  allows the blade holder  13  to be pulled out of the doctor equipment. Exactly such doctor equipment is shown in  FIG.  1   . The body piece  34  is fastened to the structure of the fiber web machine or to the doctor beam such as illustrated in  FIG.  5   . The body piece  34  has a bulge  36 , and there is a corresponding shape or recess in the blade holder  13 . This forms a hinge  35 , which allows the turning of the blade holder, but keeps the blade holder  13  attached to the body piece  34 . There is also a loading hose  37  between the body piece  34  and the blade holder  13 , into which loading hose  37  compressed air is supplied. When pressurized, the loading hose  37  expands and turns the blade holder  13  and hence the doctor blade  33  against the surface doctored. The blade holder here is of aluminum, and a press plate  38  is fastened to its surface, which press plate  38  can be of fiber-reinforced polymer material or metal; the press plate  38  is most advantageously of spring steel. The loadability and durability of such a blade holder  13  are good, in which case the doctor equipment remains operational even on heavy fiber webs. 
     The above-presented blade holder  13  with its distribution channel  11  can be pulled out of the doctor equipment  40  even during production. In this way, the blade holder  13  and the distribution channel  11  can be cleaned easily and, if necessary, maintained and adjusted. At the same time, even the doctor blade  33  can be replaced. After this, the blade holder  13  with its distribution channel  11  are pushed back into place. 
     The blowing equipment according to the invention is simple but efficient. Moreover, the mass of the distribution channel itself is small, in which case it can be supported on existing doctor equipment and even on blade holders. The mass per meter of the blowing equipment is 1000-2000 grams depending on the needed cross-sectional area of the flow. The doctor blowing is naturally located at the correct place, and the distribution channel  11  can fit even into narrow positions. The length of the distribution channel  11  is several meters, even up to 10 meters. There are on average five to ten nozzle devices  12  per length meter. Air flows that discharge from several parallel nozzle devices  12  converge, establishing a comprehensive and efficient doctor blowing. Due to the compact and light-weight structure, the blowing equipment can be placed even in existing doctor equipment without additional supporting. Moreover, efficient blowing can be accomplished in a simple manner in the tail threading area.