Abstract:
The invention concerns a loading device for the dewatering a web-forming wire, which supports and/or loads the wire of a paper machine and scrapes water from the wire surface. The loading device is loaded by a pressure medium and includes a movable loading member and a fixed base member. The loading member includes a longitudinal groove which extends the length of the loading member and the base member includes a slide rail adapted to be received in the longitudinal groove for supporting the loading member. In order to eliminate jamming phenomenon of the loading member, the loading member is supported evenly in its position in a cross machine direction and it is adapted to move towards the wire and away from the wire with aid of rollers arranged between the slide rail and the internal walls of the loading member which define the longitudinal groove.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to the web-forming section, that is, the former section of a paper machine, board machine, tissue machine or the like. More specifically, the invention concerns a loading device for supporting and dewatering a web-forming wire of a paper machine or the like.  
         BACKGROUND OF THE INVENTION  
         [0002]    Several different wire supporting and dewatering components are used in the web-forming sections of a paper machine or the like. The main purpose of these components is to generate a compression pressure and pressure pulsation in the fiber layer to be formed, to thereby promote the removal of water from the web to be formed, and at the same time contribute to the formation of the web.  
           [0003]    With regard to know arrangements for web-forming components, general reference is made to the applicant&#39;s FI patent publication 90 673, which discloses a two-wire web-forming section of a paper machine which includes a carrying wire and a covering wire. The carrying wire and covering wire together define a two-wire forming zone. In this forming zone is fitted a forming unit including a forming table and a dewatering box which generates a vacuum for removing water from the wire. The dewatering box includes a set of spaced ribs upon which the wire travels. During operation an upper one of the wires rests against the ribs and water is removed from the web by the dewatering box through the spaces defined between the rib elements.  
           [0004]    Reference is also made to the applicant&#39;s patent publication FI 95935 which relates to a rib construction for a draining device in a paper machine. Specifically a rib construction is disclosed in which a loading rib is used to support and/or load a wire in a paper machine to doctor water from the face of the wire or wires. The rib is loaded by means of a pressure medium. Between the rib and its frame part, a pressure space is formed and defined by a flexible belt. The pressure medium is introduced into the pressure space defined by the flexible belt thereby loading the rib against the wire.  
           [0005]    Reference is further made to patent publication FI 100543 which relates to a ledge for resiliently supporting a drainage wire of a paper machine. The ledge disclosed includes a head ledge which is structured and arranged across the direction of travel of the wire so the wire can slide over said ledge as the wire travels. The head ledge is rigidly connected to a movable support ledge which also extends across the direction of travel of wire and is guided on a stationary support structure. Between the movable support ledge and the stationary structure there is a resilient push device which can displace the movable support ledge together with the head ledge between a position of rest away from the wire and an operating position in which the head ledge is pressed with a predetermined force against the wire. The stationary structure has several guide arms distributed over the length of the support ledge which are the exclusive means for guiding the movable support ledge. Several guide arms arranged in pairs are provided which grip around the support ledge in the manner of a clamp.  
           [0006]    It has been a problem in known state-of-the-art loading devices that jamming of the loading member of the loading device can occur as a result of which more power is needed to make loading member move. As the loading member presses against the wire, the loading member is subjected to a torque as a result of the wire movement, which torque causes the above-mentioned jamming of the loading member. In order to overcome the jamming of the loading member a strong force must be applied to loading device. This problem is harmful to formation of the web, because the loading force placed on the wire via the loading member cannot be accurately controlled. Thus, it is a common problem that the loading member either applies too much pressure or too little pressure to the wire resulting in said web formation problems.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0007]    It is an object of the present invention to provide a loading device which overcomes the short comings of the prior art arrangements discussed above.  
           [0008]    The present invention is based on the new and inventive idea that in order to prevent the jamming phenomenon of the loading member, a pivoting roller or rollers or balls are arranged between the loading member of the device and the base member of the device, which will prevent occurrence of said jamming problems.  
           [0009]    According to one especially advantageous embodiment of the invention, such a roller is fitted to the top end of the base member of the loading device, the periphery said roller being arranged so that it abuts a portion of the loading member so that it can move in an up and down fashion relative to the base member.  
           [0010]    According to another advantageous embodiment of the invention, a pin is fitted to the top end of the base member of the loading device and, correspondingly, a ball bushing is arranged within the loading member, whereby the pin will roll along the balls of the ball bushing.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    In the following, the invention will be described in greater detail with reference to the appended drawing, to the details of which, however, the invention is not intended to be limited in any narrow sense. In the patent drawing,  
         [0012]    [0012]FIG. 1 is a diagrammatic vertical sectional view a first embodiment of the loading device according to the present invention;  
         [0013]    [0013]FIG. 2 is a diagrammatic vertical sectional view of a second embodiment of the loading device according to the present invention,  
         [0014]    [0014]FIG. 3 is a diagrammatic vertical sectional view of a third embodiment of the loading device according to the present invention;  
         [0015]    [0015]FIG. 4 is a diagrammatic elevational view of the loading device according to the present invention taken in the machine direction showing the base member, slide rail and connecting rod;  
         [0016]    [0016]FIG. 5 is a diagrammatic elevational view of the loading device according to the present invention taken in the machine direction showing an alternate arrangement of the base member, slide rail and connecting rod.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]    In accordance with FIG. 1, in a first embodiment of the invention, the loading device, which extends transversely relative to the direction of movement of the wire, that is, in the cross machine (CD) direction essentially over the entire width of the web forming section. The loading device includes a loading member  41  which extends in the CD direction and a base member  43  which also extends in the CD direction. The base member  43  has an upper portion which defines a slide rail  44 . The slide  44  may be formed integrally with base member  43  or it may separately formed and attached to an upper surface of the base member  43 .  
         [0018]    The loading member  41  includes a lengthwise longitudinal groove  54  formed in a lower face thereof, said longitudinal groove extending in the cross machine direction. The loading device according to the invention is structured and arranged so that loading member  41  is maintained in stable position in cross machine direction but is able to move towards and away from the wire while being supported on slide rail  44  to thereby enable the selective loading and unloading of the wire.  
         [0019]    A planar and/or inclined ceramic piece  42  is coupled to the upper part of loading member  41 . The ceramic piece  42  is structured and arranged to drag against the wire surface loading the same. The ceramic piece scrapes the lower surface of the wire and in this manner serves to remove water therefrom. The water acts as a lubricated fluid between the ceramic piece  42  and the wire.  
         [0020]    The loading device according to the present invention further includes roller means  100  which also extend substantially along the length of the device in the cross machine direction.  
         [0021]    As shown in the figures the loading member  41  is substantially U-shaped and includes two substantially parallel arms  53 . The parallel arms define an upper internal longitudinal groove  59  and said longitudinal grove  54 . Groove  59  and  54  are separated by a shoulder portion  60  of the arms as shown. Internal longitudinal groove  59  is adapted and to receive said roller means  100  such that an internal wall of each of said parallel arms abuts said roller means  100  and acts as a contact surface between said loading element  41  and said roller means.  
         [0022]    In the embodiment of the invention shown in FIG. 1, the loading member  41  moves in the up-and-down direction in relation to slide rail  44 . In order to maximize easy sliding, rolling is promoted with the aid of roller  100  between body part  43 , slide rail  44  and loading member  41 . According to the invention, roller  100  is coupled to slide rail  44  of the loading element with the aid of rotating shaft  110 .  
         [0023]    In the first embodiment of the invention shown in FIG. 1, a single roller  100  arrangement is preferably employed. However, a multiple roller arrangement may also be employed.  
         [0024]    To make sure that rolling friction is constantly maintained between roller  100  and the loading member  41 , the loading member  41  and base member  43  are structured and arranged so when they are fit together a certain degree of play exists therebetween. As a result of this arrangement when the force caused by the wire is imposed upon the loading member  41 , base member  43  does not generate friction force except on a side of roller  100 . In this manner the smooth movement of the loading member  41  is insured and the jamming problems associated with prior art arrangements is avoided.  
         [0025]    In a second embodiment of the invention, shown in FIG. 2, the loading device extends transversely to the direction of movement of the wire, that is, in the CD direction, essentially over the entire width of the web forming section. The device includes a loading member  41  in the CD direction and a base member  43  also arranged in the CD direction. A top part of the base member forms a slide rail  44 . In accordance with the invention, loading member  41 , which lengthwise has a longitudinal groove  54 , is supported evenly in its position in the CD direction and is adapted to move towards and away from the wire supported by slide rail  44  and by roller means  100 , which are installed in the upper surface of slide rail  44  with the aid of rotating shafts  110 . The upper side of loading member  41  drags against the wire surface loading the same, whereby the loading member  41  scrapes water to be removed from the web away from the lower surface of the wire.  
         [0026]    In the embodiment shown in FIG. 2, loading member  41  is adapted to move in an up-and-down direction in relation to slide rail  44 . In order to maximize ease of sliding, rolling is promoted with the aid of rollers  100  arranged between base member  43 , slide rail  44  and loading member  41 . In accordance with the invention, rollers  100  are coupled to body part  43  with the aid of rotating shafts  110 .  
         [0027]    In the second embodiment of the invention, rollers  100  are mounted along either side of slide rail  44  as show in FIG. 2. Each roller  100  and their corresponding rotating shafts  110  extend in the CD direction across the width of loading member  41 . The rotating shafts  110  are coupled to the slide rail  44  at least at their ends. It is advantageous that over the length of each roller  100  supporting bearings (not shown in FIG. 2) are arranged at selected intervals along the length of the roller. For example roller or slide bearings could be arranged in order to support rollers  100  between their ends. Alternatively, slide rail  44 , which typically is an integral part with body part  43 , may be provided with several rollers  100  and corresponding mutually spaced indentations (not shown in FIG. 2) which are structured and arranged to receive a corresponding one of said rollers  100 . The indentations are arranged so that the roller  100  is exposed towards loading member  41  in the manner shown in FIG. 2.  
         [0028]    In the embodiment of the invention shown FIG. 2, each roller  100  has only one stop face, whereby a constant rolling friction is maintained between loading member  41  and rollers  100 , and thus their mutual fitting can be made essentially with an absence of play.  
         [0029]    Two possible constructions of the roller means  100  discussed above are shown in FIGS. 4 and 5 which depict the loading device according to the present invention in a machine direction. It is noted that the loading member  41  has not been shown in FIGS. 4 and 5 merely to enable the clear viewing of the remaining structural elements of the device. Nonetheless, it is appreciated that loading member  41  is arranged on top of the base member  43  and glide rail  44  as shown in FIGS.  1 - 3 . In one arrangement of the roller means, shown in FIG. 4, a single roller  100  extends substantially across the entire width of the loading device. The roller  100  is coupled at each of its ends to an upright  44   a  of the glide rail  44  by means of rotating shaft  110 . Arranged on an upper surface of glide rail  44  are support bearings  105  or the like which are arranged at selected intervals along the length of the roller  100  to thereby assist in supporting said roller  100 . The upper surface of glide rail  44  may be provided with grooves or the like which would function as a seat for the support bearings  105 .  
         [0030]    In an another arrangement of the roller means, shown in FIG. 5, multiple rollers  100  are arranged at selected intervals in the cross machine direction. In such an arrangement the slide rail  44  is provided with a plurality of spaced uprights  44   a.  A pair of each of the uprights define an indentation, cavity or the like in the slide rail between a respective pair of the upright, the indentation being adapted to receive a roller Thus, each of the rollers  100  are structured and arranged to fit between two corresponding uprights  44   a  as shown. Each roller  100  coupled to two corresponding uprights by a rotating shaft  110  which is coupled at each of its ends to a corresponding one of the uprights  44   a.  It is also possible that a single rotating shaft  110  could be employed which would pass through all of the uprights  44   a  and rollers and be coupled at each of ends in a manner similar to the arrangement shown in FIG. 5.  
         [0031]    Where a plurality of rollers  100  a employed, it is preferable that each one of the rollers being arranged at uniform intervals of 500 mm over the entire width of the device. It is emphasized that the rollers may be of different lengths and that it is possible to implement a roller structure according to the invention with one roller  100  only.  
         [0032]    In both embodiments of the invention, as shown in FIGS. 1 and 2, it is advantageous that the individual rollers  100  are made of a material which withstands the pressure impact to which it is subjected and which significantly reduces friction that significantly impedes the movement of loading member  41 .  
         [0033]    Preferably the loading member  41 , base member  43  and slide rail  44  are made of glass fiber and, in addition, a wear-resistant ceramic piece  42  is mounted on the end of lath loading member  41 . In performed tests it has proved advantageous at the lower slide surface of body part  43  to mount a friction-reducing slide piece  45 , which reduces friction between loading member  41  and base member  43 . Slide piece  45  functions to further enable the easy adjustment and movement of loading member  41  relative to the base member  43 . Instead of slide part  45  it is also possible to use ball/round bars in order to reduce friction even more between loading member  41  and base member  43 .  
         [0034]    In another embodiment of the invention, shown in FIG. 3, loading device, which extends transversely to the direction of movement of the wire, that is, in the cross machine direction essentially over the entire width of the web, includes a loading member  41  which is also arranged in the CD direction. The device further includes a base member  43  arranged in the CD direction. A top portion of the base member  43  includes a slide part/parts  44 , in relation to which loading member  41  moves towards and away from the wire.  
         [0035]    In accordance with the invention, the loading member  41  includes lengthwise a longitudinal groove  54 . The loading member  41  is adapted to move in an up and down manner relative to the wire. The loading member is supported by slide part/parts  44  and ball means  100  which are arranged in the manner shown in FIG. 3.  
         [0036]    The planar and/or inclined upper portion of loading member  41  drags against the wire surface loading the wire, whereby the loading member  41  functions to remove water from the lower surface of the wire.  
         [0037]    In the third embodiment of the invention shown in FIG. 3, loading member  41  moves in an up-and-down direction in relation to slide part  44 . To maximize ease of movement, balls  100  are arranged between an internal face of the loading member  41  and an external surface of the slide part  44 . According to the invention, balls  100  are mounted to loading member  41  with the aid of ball bushing  49 .  
         [0038]    In third embodiment of the invention, several balls  100  are mounted in the manner shown in FIG. 3 to form a ball stack. A plurality of these individual ball stacks are arranged in the transverse machine direction across the length of the loading device. Preferably each of the stacks are arranged at a selected distance from one another. For example the distance from stack to another may be between 200 and 280 mm in the transverse machine direction. In this embodiment it is preferable that slide part  44  is defined by a plurality of pins or the like formed in the top part of base member  43  and that the top parts of the slide parts  44  are fitted with some play with relation to the ball bushings  49 .  
         [0039]    Ball bushings  49  are provided to house each stacks of balls  100 , the ball bushings  49  being secured to loading member  41 . In this manner the ball bushings  49  and balls  100  therein allow a smooth relative movement between slide part  44  defined by said pins and loading member  41  in the up-and-down direction and at the same time preventing slide part  44  and loading member  41  from jamming. The balls  100  fitted into ball bushing  49  preferably form a bearing, the type of which is e.g. SKF LBBR 12-2LS/HV6.  
         [0040]    As was described in the foregoing in connection with the first and second embodiments of application of the invention, it is also possible in this third form of application of the invention when desired to mount a friction-reducing slide piece  45  on the lower slide surface of body part  43 , which slide piece reduces friction between  41  and body part  43 .  
         [0041]    In all of the embodiments discussed above with reference to FIGS.  1 - 3 , a flexible belt  46  extends along each side of the device as shown. Each flexible belt  46  is joined to the lower edge of the loading member  41 , and the belt is attached to the a part of body part  43  in such a way that U-shaped loops  48  are formed which extend downwardly as shown. Specifically a first longitudinal edge of belt  46  is attached to loading member  44  and a second longitudinal edge of belt  46  is attached base member  43 . The ends of each belt  46  are attached to a groove  56  formed in the loading member  41  and the base member  43 . To the exteriors sides of the loading member  41 , outside belt  46 , are attached shield plates  55  which limit the lateral movement of belt  46 . Belt  46  has a thickness of about. 0.1-3 mm, preferably 1-2 mm, and is preferably made of rubber or some other similar flexible material.  
         [0042]    Using attaching elements  58 , the loading device is attached to the other body of the machine. The loading force of loading member  41  is brought about by generating a loading pressure by introducing a pressure medium, such as air, through channel  57  into the space defined by the flexible belt  46 , loading member  41  and base member  43 .  
         [0043]    The loading pressure is reduced by lowering the pressure of the medium. Upon removal of pressure the loading member  41  will return to its bottom position as a result of gravity thereby unloading the wire. A vacuum may also be used to promote the return of the loading member  41  back to its lower position.  
         [0044]    The examples of the invention provided above are not meant to be exclusive. Many other variations of the present invention would be obvious to those skilled in the art, and are contemplated to be within the scope of the present invention.