Patent Publication Number: US-7217341-B2

Title: Treatment equipment, including a beam, for a paper machine

Description:
This invention relates to treatment equipment, including a beam, for a paper machine, the beam having a shaft at both of its end components, equipped with a bearing assembly, which is attached to the paper machine frame and adapted to allow the beam to pivot in relation to the bearing assembly and move in the axial direction, and the said treatment equipment further comprising a support device at least in one of the end components of the beam for turning the beam, and an oscillator for moving the beam back and forth in the axial direction, and the said support device comprising a swing arm immovably set on the shaft and an actuator connected thereto. The invention also relates to similar treatment equipment without an actuator. 
   Several doctors are used in paper machines as well as in other forming machines. In connection with rolls and cylinders, in particular, the doctors are used to remove the paper web to the pulper. The doctor is also used to clean the surface of a roll or a cylinder. The surface to be cleaned is usually doctored with a doctor blade, which is attached to the doctor beam by means of its blade holder. The beam is supported by its shafts with bearing assemblies, which allow the beam to move in the axial direction as well. As the result, an oscillator arranged in the doctor provides a lateral oscillating movement for the beam, which improves the cleaning performance and reliability of the doctor blade. At least at one end of the beam, the shaft is additionally fitted with a support device, which enables turning the doctor to the desired position by using the actuator of the support device. In addition to turning, the support device also keeps the doctor in the adjusted position. 
   A Finnish utility model No. 3718 sets forth a doctor, in which a simple hydraulic cylinder can be used as the actuator for the support device. The hydraulic cylinder is connected to a swing arm included in the support device, and the swing arm is connected to a shaft. Between the swing arm and the shaft there is a cogged joint, which not only permits the oscillating movement, but also transmits the turning movement. That is, the swing arm is kept in place during the shaft movement. However, the manufacture of a cogged joint is laborious and expensive. In addition, the proposed support device requires a large installation space, especially in the vertical direction. The cogged joint also inevitably becomes large in size, and remarkable frictional forces are then generated on its counter surfaces, which increases the power requirement of the oscillator. Furthermore, turning of the beam for example to the service position is impossible. 
   Doctors are also used in coating as well as without an actuator for turning the beam. In this case the beam is set to a desired position and the doctor blade is turned by means of loading hoses adapted to the blade holder. In the prior art technique, the swing arm arranged in the beam is supported to the bearing assembly or generally to the paper machine frame by means of a turnbuckle screw. In this case, the oscillating movement of the beam makes the turnbuckle screw swing, which further leads to distortion of the beam. In practice, the beam is in a continuous rotary motion, which produces uneven wear of the doctor blade. Also, the frictional force generated by the doctor blade varies, which makes the resistance caused by the doctoring vary. For example, the dryer groups of a paper machine have several doctors. The effect of resistance is remarkable, when the resistance peaks of several individual doctors apply simultaneously. In this case, running of the entire paper machine becomes jerking, which hampers the production and causes web breaks. This jerking also stresses the gearings and the electric motors actuating them. 
   The object of this invention is to provide novel treatment equipment, including a beam, for a paper machine, being more economical to manufacture and use than heretofore and having a larger opening angle than before. Another object of the invention is to provide treatment equipment, with which the disadvantages of the prior art technique are avoided. The characteristics of the treatment equipment according to this invention become evident from the appended claims  1  and  8 . In the treatment equipment according to the invention, the support device has a novel design, which permits both the turning movement and the axial movement of the beam. In spite of this, the support device and its actuator, if any, can be securely attached without harmful bending stresses. Also, the construction is easy to install in existing treatment equipment. In addition, the construction requires only a reduced space for installation. Additionally, the application of the support device is independent of the doctor or oscillator used. With a simple design, the back and forth rotary motion of the beam caused by oscillation can be avoided. 

   
     The invention is described below in detail by making reference to the enclosed drawings, which illustrate some of the embodiments of the invention, in which 
       FIG. 1   a  is a principal drawing of a front view of the doctor according to the invention shown in the machine direction, 
       FIG. 1   b  is an axonometric view of the end component of the treatment equipment according to the invention, 
       FIG. 2   a  is a top view of the end component of the treatment equipment according to the invention, 
       FIG. 2   b  is a sectional side view in plane A—A of the end component illustrated in  FIG. 2   a,    
       FIG. 3   a  shows a part of the support device illustrated in  FIG. 2   b  separated from the construction, 
       FIG. 3   b  shows a second embodiment of the component illustrated in  FIG. 2   b,    
       FIG. 3   c  shows the counter component of  FIG. 3   b  separated from the construction, 
       FIG. 4   a  shows a modification of the part of the support device illustrated in  FIG. 3   a , connected to the beam, 
       FIG. 4   b  is s sectional view in plane B—B of  FIG. 4   a,    
       FIG. 5   a  is a side view of the second embodiment of the end component of the treatment equipment according to the invention, 
       FIG. 5   b  is a top view of the end component of  FIG. 5   a,    
       FIG. 6   a  shows the brackets of the treatment equipment according to the invention at the first end station of the oscillating movement, 
       FIG. 6   b  shows the brackets of  FIG. 6   a  at the second end station of the oscillating movement. 
   

   In  FIG. 1   a , the treatment equipment according to the invention is a doctor  10 , which is arranged in connection with a roll  11 . The surface of the roll  11  is doctored by means of a doctor blade  13  set in a blade holder  12 ′, with the doctor blade pointing here diagonally upwards. The blade holder  12 ′ is attached to the beam  12  of the doctor  10 . Due to the beam, sufficient rigidity is achieved for the doctor, allowing thus to support the doctor solely at its ends. Besides the beam, another sufficiently rigid construction can also be used. Shafts  15  are attached to the ends of the beam  12  by means of flanges  14 , the shafts being supported to the paper machine frame with bearing assemblies  16 . As is well known, such bearing assemblies have a special construction, thus allowing for the beam to both pivot in relation to the bearing assembly and to move in the axial direction. In  FIG. 1   a  there is additionally an oscillator  17  at the other end of the shaft line, the oscillator being of a certain known type, and hence its construction is not set forth here. The oscillator  16  provides a back and forth linear motion, indicated with a double-headed arrow in  FIG. 1   a , to the beam  12 . The stroke length of the oscillator is typically 10–20 mm. 
   In addition to the above, the doctor  10  also comprises a support device  18  at least at one of the ends of the beam  12 . In  FIG. 1   a  the support device  18  is installed at both ends of the doctor  10 . The support device is used for turning the beam to the desired position and it can also be used for loading the doctor. Generally the support device  18  comprises a swing arm  19 , immovably fixed to the shaft  15 , and an actuator  20  connected thereto. The end component of the treatment equipment according to the invention is shown in greater detail in  FIGS. 2   a  and  2   b . According to the invention, in connection with the bearing assembly  16  there is unexpectedly an auxiliary arm  21 . The auxiliary arm  21  is adapted free in the radial direction and locked in the axial direction in relation to the bearing assembly  16 . That is, the auxiliary arm can be pivoted while it remains in place in the axial direction. In addition there is a connection  22  between the swing arm  19  and the auxiliary arm  21 . The connection  22  permits the axial movement of the swing arm  19  in relation to the auxiliary arm  21  without a radial distortion of the swing arm  19 . Consequently, the swing arm  19  connected to the beam  12  can move in the axial direction. In addition, the connection  22  transmits the support force from the actuator  20 , which is arranged between the bearing assembly  16  and the auxiliary arm  21 . By means of the proposed solution, the oscillation movement remains a pure linear movement, and as the result, the doctor blade wears uniformly and the blade loading is kept stable. 
   For clarity, the actuator is not shown in  FIG. 2   a , which however shows a cross-sectional view of the support arm  23  attached to the bearing assembly  16 . The actuator  20  can be of a conventional design, and it is attached between the support arm  23  and the auxiliary arm  21 . Generally the auxiliary arm  21  is mounted, free in the radial direction, on the same swing axis as the shaft  15  by means of a bearing assembly. In  FIG. 2   b  the auxiliary arm  21  comprises a ring  24 , which is fitted with a suitable bearing. Furthermore, extra loadings can be avoided by arranging the actuator  20  essentially at the connection  22  in the axial direction. In this way the force from the actuator is transmitted directly from the auxiliary arm to the swing arm through the connection. The movement of the auxiliary arm  21  is illustrated with a double-headed arrow in  FIG. 2   b . In  FIG. 2   b  the actuator  20  is attached in the immediate vicinity of the connection  22 . The attachment point of the actuator can also be in some other point of the ring, in which case more freedom is achieved for the positioning of the actuator than heretofore. 
   To enable the axial movement of the swing arm  19  the connection  22  comprises elements, composed of roller bearings  25  or slide bearings  26 . Generally the roller element  27  included in the roller bearing  25  is arranged in the swing arm  19  or in the auxiliary arm  21 . In this case, there are axial direction counter surfaces  28  arranged correspondingly in the auxiliary arm  21  or the swing arm  19  for the roller element  27 . In  FIG. 2   a  the roller element  27  is adapted in the swing arm  19 , but it can as well be set in the auxiliary arm  21 . For clarity, only one counter surface  28  is shown in  FIG. 2   a . In  FIG. 2   b , on the contrary, both counter surfaces are shown, in which case the connection functions to both directions. In the proposed embodiment the roller element  27  is a roller  29 , which rolls in a slot  31  formed by plate components  30 . For transmitting the force, the roller  29  is set in the tangential direction. That is, the roller  29  is mounted with bearings on the radial shaft of the auxiliary arm  21 . 
     FIG. 3   a  shows the swing arm  19  of  FIG. 2   b  separated from the construction. The swing arm  19  also includes a roller element  27  formed by the roller  29 . If necessary, suitable adjustment elements are arranged between the connection and the swing arm for adapting the various parts in a correct position in relation to each other. Generally the slide element  44  included in the slide bearing  26  is arranged in the swing arm  19  or in the auxiliary arm  21 . In this case, there are axial direction counter surfaces  28  arranged correspondingly in the auxiliary arm  21  or the swing arm  19  for the slide element  44 . A clearance-free connection can be easily obtained with the proposed slide bearing assembly. Here the slide element  44  is composed of a dowel pin  32 , with the corresponding cylindrical hole  33  being made in the auxiliary arm  21 . The solution is simple, but allows a smaller angle difference between the swing arm and the auxiliary arm than the roller  29  shown in  FIG. 3   a.    
   The roller bearing can also be made clearance-free by arranging at least two roller elements  27  in it for example as shown in  FIG. 4   a . In this case, clearances can be removed by adjusting the position of the roller elements in relation to the counter surfaces.  FIG. 4   b  shows one solution for adjusting the position of the roller elements. Here the rollers  29  have eccentrically set shafts  34 , which allows adjusting the position by pivoting the shaft  34 . Finally the shaft is locked in place. 
     FIGS. 5   a  and  5   b  show a second embodiment of the treatment equipment according to the invention. Here the shaft  15  is supported to the beam  12  by means of an intermediate arm  35 . In this case the swing arm  19  is composed of a combination of lugs  37 , beam  12 , and intermediate arm  35 . In this embodiment, too, the auxiliary arm  21  is mounted by bearings on the same swing axis as the shaft  15 .  FIG. 5   b  illustrates the connection  22 , which is composed of the slide bearing  26 . The same reference numbers are used for functionally similar parts. Preferably, a cylindrical joint pin  36  is attached to the auxiliary arm  21 , in which case the counter surfaces of the slide bearing  26  are in the lugs  37  attached to the beam  12 . This allows achieving sufficiently large and durable slide surfaces. In this embodiment, too, it is possible to use a conventional actuator  10 , which is supported to a crossbeam  38  supporting the bearing assembly  16 . 
   Such treatment equipment also exists in which the above described actuators are not needed. In these treatment devices the beam is immovably fixed to a certain position. For loading and adjustment, the blade holder is equipped with separate loading elements. That is, the beam is fixed in a certain position by means of a support element arranged in the end component. According to the invention, the support element is composed of the auxiliary arm  21  arranged in connection with the bearing assembly  16 . The auxiliary arm  21  is unexpectedly adapted to the same direction as the swing arm  19  and locked in both radial and axial directions in relation to the bearing assembly  16 . In addition, there is a connection  22  between the swing arm  19  and the auxiliary arm  21 , allowing for the swing arm  19  to move in the axial direction in relation to the auxiliary arm  21  without a radial distortion of the swing arm  19 . In this case the swing arm can move freely in the axial direction together with the beam.  FIG. 1   b  shows an embodiment without an actuator, in which the connection  22  is composed of two functional joints  39 . In the joints  39  the swing axes of the pivoting points are parallel, in which case a parallel displacement of the arms is possible and almost frictionless at the same time. The functional joints  39  are preferably made as one double joint  40 . In this case the parallelism of the swing axes can be ensured. In addition, the double joint  40  is preferably connected to the auxiliary arm  21  and/or the swing arm  19  by means of the adjustment elements  41 .  FIG. 1   b  illustrates one simple adjustment element  41 , which is composed of curved slots  42 . In this case the position of the double joint  40 , attached with two screws, can be changed in relation to the swing arm  19 . The actual positioning of the beam  12  is made by changing the attachment of the auxiliary arm  21  to the bearing assembly  16 . For this the auxiliary arm is provided with closely distributed holes  43 . The accuracy of the adjustment can be improved by adding holes in the swing arm, too. 
     FIGS. 6   a  and  6   b  show a swing arm  19  and an auxiliary arm  21  connected with a double joint  40 . In practice, the auxiliary arm is kept in place all the time while the swing arm is moving axially. The double joint  40  enables this movement while it simultaneously transfers the support force from the auxiliary arm to the swing arm. A double joint is extremely maintenance-free and withstands various operating conditions. Consequently, it can be well applied in difficult paper machine conditions. In addition to the proposed, the connection can include elements that enable the axial movement of the swing arm, composed of roller bearings or slide bearings, as in the above described embodiments of the treatment equipment equipped with an actuator. 
   The treatment equipment according to the invention and especially the associated connection that enables the axial movement is simple and reliable. The connection can be implemented in many different ways providing a suitable connection for the treatment equipment concerned. In addition, the connection requires only a reduced installation space and generated frictional forces are small. The connection can also be easily made clearance-free, which eliminates vibration problems of the beam.