JP2566012Y2 - Web dryer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking machine with a blow box which effectively suppresses the tendency of the web to adhere to the dryer when the felt separates from the dryer. The present invention relates to a web dryer for a machine. [0002] In the papermaking process, production rates are constantly increasing. Currently, in high speed paper production, a single supporting felt is used throughout a group of dryer cylinders to convey a wet paper web sequentially around multiple dryer cylinders. . The felt is guided in a meandering manner through successively arranged dryer cylinders. That is, the felt is guided around the upper side of the dryer cylinder arranged on the upper side, and then guided through the lower side of the dryer cylinder arranged on the lower side, and then again the dryer cylinder arranged on the upper side. Guided through the upper side of. The web carried and conveyed on one side of the felt is sandwiched between the felt and the dryer cylinder as the felt moves around above the upper dryer cylinder, but the felt is When moving around the lower side of the machine cylinder, the felt is conveyed while being exposed on the side opposite to the side facing the dryer cylinder. Thus, the web leaves the upper dryer cylinder away from the upper dryer cylinder and toward the lower dryer cylinder after the felt has turned above the upper dryer cylinder,
It must be conveyed away from contact with the dryer cylinder while maintaining its adherence to the felt from being clamped between the felt and dryer cylinder. SUMMARY OF THE INVENTION [0006] The invention of the present application is based on the fact that the web conveyed while being pressed and held between the felt and the upper dryer as described above. It is an object of the present invention to provide an improved papermaking dryer which ensures that the web follows the felt when it is necessary to leave the upper dryer following the above. In order to achieve the above object, the present invention proposes that the felt is directed from the upper dryer to the lower dryer from a first end facing the linear contact point tangentially away from the upper dryer. For a felt extending linearly along one plane, a plane arranged at an acute angle to the straight part of the felt so as to define a space that gradually expands in the direction of movement of the felt. Blow with a wall
A box is provided, and a linear orifice is provided on the wall of the blow box at a position facing the linear contact point of the felt, and air is blown from the orifice in a direction opposite to the felt moving direction. The air blown from the linear orifice flows in a spreading direction through a wedge-shaped space formed between the curved portion of the felt toward the linear contact point and the wall of the blow box, so that the ejector by the blown air is ejected. A negative pressure is generated at the linear contact point by the effect, and the negative pressure draws the web toward the felt side at the linear contact point, and the felt moves from the linear contact point toward the lower dryer. By expanding the space between the blow box wall and the felt in the divergent state in the moving direction of the felt, the web is further sucked in the felt. Blow, which exerts pressure on the web to the side of the felt for the most important moment, which determines that the web leaves the contact with the upper dryer and follows the felt, followed by some time. It proposes incorporating the box structure into a papermaking dryer. [0013] [0021] [0021] [0021] [0018] [0021] [0021] [0021] [0021] [0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 of the present invention shows a portion of a dryer designated generally by the reference numeral 10. The dryer unit 10 includes at least a first dryer 12, a second dryer 14, and a third dryer 16, wherein the first dryer 12 and the third dryer 16 are upper dryers and a second dryer. 14 is a lower dryer. The felt F and the web W pass around the first dryer 12. The felt F and the web W are branched from the first dryer 12 near the branch holding portion 18. The felt and web move together from the first dryer 12 to the periphery of the second dryer 14 and further to the periphery of the third dryer 16. As shown in FIG. 1, the web W tends to adhere to the surface 20 of the first dryer 12 at the branch holding portion 18 and to separate from the felt F. In addition, the air dragged in the vicinity of the outer periphery 22 of the second dryer 14 is trapped in the vicinity of the merging and holding portion 24 of the second dryer 14. The holding portion 24
Is defined by the felt F between the first and second dryers 12 and 14 and the second dryer 14. The pressure accumulated in the junction holding section 24 reduces the air flow through the felt F, which tends to reject the web W from the felt F while the felt and the web pass around the second dryer 14. Has a tendency to produce. Similarly, as the web and felt travel upward from the second dryer 14 to the third dryer 16,
If a conventional air box is placed in the recess 26 defined by the moving web W and the felt F, such air box will tend to increase the air pressure in the recess 26. As a result, the felt F is moved upward, particularly at the junction holding portion 28 of the third dryer 16.
Increases the possibility that the web W separates from the web. FIG. 2 shows one proposal according to the prior art for reducing the above-mentioned pressure rise at the junction holding section 24. The above prior art proposal provides a blow box for directing compressed air 32 in a direction opposite to the direction of travel indicated by the arrow 34 of felt between the first dryer 12 and the second dryer 14. 30. FIG. 3 shows a state in which the outer periphery of the second dryer 14 is cut from the felt between the first dryer 12 and the second dryer 14 in a direction opposite to the rotation direction of the second dryer indicated by an arrow 38. 2
2 shows another proposal according to the prior art, including an air box 36 with means for directing the air flow towards 2; FIG. 4 is a side sectional view of the air box 40 according to the present invention. The blow box 40 is moved from the first dryer 12 to the periphery of the second dryer 14 and further to the third dryer 1.
6 is located in a recess 26 defined by a web W and a felt F that move along with the outer circumference of 6. blow·
Box 40 includes a wedge-shaped box extending from between first dryer 12 and third dryer 16 to near second dryer 14. The box 40 is connected to a compressed air source 42 to maintain the web W in close contact with the felt F when the web W and the felt F are branched from the first dryer 12 at the branch holding portion 18. . The box 40 suppresses the tendency of the web W to adhere to the surface 20 of the first dryer 12 when the felt F branches off from the first dryer 12,
The compressed air is directed to the felt in such a way that the web W is forced towards the felt F, and then the air is directed by the arrow 46 in a direction opposite to the direction of rotation of the first dryer 12 as indicated by the arrow 34. One orifice 44 is positioned adjacent the first dryer 12 for redirection as shown. As shown in FIG. 4, the jet of air can be turned by the action of the Coanda effect.
By providing a curved surface on one side of the orifice or nozzle, the air direction is changed. As shown in FIG. 4, the air is directed tangential to the first dryer and in a direction opposite to the direction of rotation of the first dryer. More specifically, as shown in FIG. 4, the blow box 40 includes a first dryer 12 and a third dryer 16.
A wedge-shaped box including a base wall 48 extending radially relative to the second dryer 14 halfway between. The base wall 48 extends in the cross-machine direction as described below. The curved wall 50 is such that the web and the felt
4 extend from the base wall 48 toward the converging and holding portion 24 that converges on the base 4. The curved wall 50 is provided on the outer periphery 22 of the second dryer 14.
Is matched. The curved wall 50 extends in the cross machine direction. The diffuser wall 52 is arranged on the opposite side of the base wall 48 such that the diffuser wall 52 extends from the curved wall 50 toward the first dryer 12. The diffusion wall 52 extends in the cross machine direction. The connection wall 54 is arranged on the opposite side of the curved wall 50 so that the coupling wall 54 extends between the diffusion wall 52 and the base wall 48 in order to connect the base wall 48 and the diffusion wall 52. As shown in FIG. 7, the first end wall 56 and the second end wall 58 are separated from each other in the cross machine direction,
Further, they are fixed to the base wall 48, the curved wall 50, the radiation wall 52, and the connecting wall 56, respectively, for defining the wedge-shaped box 40 therebetween. The diffuser wall 52 is used to induce a local vacuum between the felt F and the diffuser wall 52 when the web W and the felt F are moving with respect to the box 40, so that the first dryer 12 can be a Felt F in the direction to the second dryer 14
The distance between and is gradually widened. The radiation wall 52 is disposed in the first plane 60, and the felt F between the first dryer 12 and the second dryer 14 is disposed in the second plane 62. The first plane 60 and the second plane 62 are between each other so as to induce the local vacuum so that any tendency of the web W to move away from the felt F is completely suppressed by the local vacuum. They are arranged at an angle. The local vacuum is applied to the felt F against the diffuser wall 52.
When the movement speed of the felt F and the web W that closely follows the felt F increases, and accordingly the tendency of the web W to move away from the felt increases, The induced local vacuum is correspondingly increased to compensate for such a tendency of the web W to move away from the felt F. In the illustrated and preferred embodiment of the present invention, the first plane 60 and the second plane 60 are maintained such that the local vacuum induced by the dissipating wall 52 helps maintain the local vacuum induced by the compressed air 46. The plane 62 and 0.
The distance from one another is gradually increased with an angle in the range of 1 to 5.0 degrees. In addition, the air box 40 has an arrow 66 in the recess 26 near the outer periphery 22 of the second dryer 14 as the second dryer 14 rotates as indicated by arrow 38.
Is prevented from flowing between the curved wall 50 and the outer periphery of the second dryer 14 toward the junction 24 of the web W and the felt F to the second dryer 14. And between the base wall 48 and the outer periphery 22 of the second dryer 14 includes one air diverting means, generally indicated at 64. The diverting means 64 is provided on the outer periphery 2 of the
Air near 2 is diverted out of the recess 26 along the base wall 48. Preferably, the air diverting means 64 is a single brush. The air diverting means or brush 64 causes air near the outer periphery 22 of the second dryer 14 to be directed along the base wall 48 as shown by arrow 66 and further out of the recess 26, thereby reducing Second dryer 14 and third dryer 1
6 induces a local vacuum in the web W and the recess between the felt F and the base wall 48. This local vacuum near the web and felt between the second dryer 14 and the third dryer 16 creates a web W to the felt between the second dryer 14 and the third dryer 16. Enhances binding. The blow box 40 is mounted on the pivot at 68 in connection with the first dryer 12 so that if the web W breaks or wraps around the first dryer 12 In order to prevent the destruction of the first dryer 40, the radiation wall 52 is kept away from the first dryer 12.
Box 40 is inclined with respect to 2. As shown in FIG. 4, the base wall 48 is mounted on the pivot at 68 and the box 40 pivots about a pivot 70 which is arranged parallel to the cross machine direction 72. This is shown in more detail below in connection with FIG. As shown in FIG. 4, the pivot 70 is located far from the connecting wall 54. The base wall 48 of the blow box 40 defines one opening 74 for directing the air flow indicated by arrow 76 from within the box 40 to the recess 26, and the air flow 76 Are the second dryer 14 and the third dryer 16
And flows out of the recess 26 to induce a local vacuum in the recess 26 between the felt F and the base wall 48 located between them. This induced local vacuum is applied to the second dryer 14
Helps to keep the web W in close contact with the felt F between the first dryer 16 and the third dryer 16. FIG. 5 is a graph showing how the degree of vacuum induced by airflow 46 through orifice 44 varies with distance from orifice 44. As is evident from the graph of FIG. 5, the orifice 44 is even more so when placed closer to the contact point 78 of the felt F that branches off from the first dryer 12 rather than closer to the second dryer. Web W to maintain bond with felt F
A very useful vacuum can be obtained to drive the vacuum. FIG. 6 is a side cross-sectional view of another alternate embodiment of the present invention, wherein like parts are designated by like numerals used with respect to the embodiment shown in FIG. However, in the alternative embodiment of FIG. 6, the suffix A is added to those numbers. FIG. 6 shows the first dryer 12A and the second dryer 14
A and the third dryer 16A are shown, around which the web WA and the felt FA pass. Blow box 40A is located in recess 26A. Blow box 40A includes a baffle 80 disposed within box 40A and extending across box 40A between diffuser wall 52A and base wall 48A, with box 40A comprising a first compartment 82 and a second compartment. 84. The first compartment 82 is connected to the compressed air source 42A, and the first compartment 82 defines a hole 86 through which fluid can flow between the first compartment 82 and the second compartment 84. A local vacuum is induced in the second compartment 84 as a result of the air, indicated by, flowing from the holes 86 toward the opening 90 defined by the base wall 48A. The second compartment 84 is a web W
A and the felt FA define an inlet 92 arranged in the vicinity of a point 24A where the second dryer 14A joins, and
Air, as indicated by arrow 94, passes through inlet 92 and into second compartment 84 to suppress any tendency of web WA to move away from felt FA as web WA passes around second dryer 14A. And inflow. FIG. 7 is a perspective view of still another embodiment of the present invention. Although the same reference numerals are used to designate similar components throughout the alternate embodiment, the alternate embodiment of FIG. 7 has a number with a suffix B added. The orifice 44B as shown in FIG.
Is a web W that tends to adhere to the first dryer rather than closely follow the felt FB between the first and second dryers.
In order to suppress any tendency of B, the air curtain indicated by arrow 46B is directed to the first dryer, and then tangential to the first dryer and in a direction opposite to the rotation direction of the first dryer. A single elongated slot extending in the cross-machine direction 72 to direct the air curtain. As shown in FIGS. 7 and 8, the diffuser wall 52B is connected to the first end wall 56B of the box 40B.
And a first slot 96 and a second slot 98 disposed proximate to the second end wall 58B. These slots 96, 98 provide a first air flow and a second air flow, indicated by arrows 100 and 102, for causing the edges 104, 106 of the web W to closely follow the respective edges 108, 110 of the felt. Are directed sideways to the recess. These edges 104, 106 of the web WB are shown in more detail in FIG.
02 helps to reduce the tendency of the web WB to wrinkle by pressing the web WB edges 104, 106 tightly against the felt FB edges 108, 110 and further suppresses outward hot airflow from the recesses. Show that it is also useful. 7 and 8 are not only useful to assist in sealing the recess against air loss, but also serve the purpose of eliminating the need for side plates to prevent such air leakage. . In addition, air 100, 102
Lateral flow prevents compressed air flow from inside the recess to the outside, which tends to make monitoring and adjusting the dryer section 10 uncomfortable. As shown in FIG. 8, the main body of the air jet or air flow 100, 102 and the air dragged by the main body follow the curved surface 97 of the end wall 56 </ b> B in a direction away from the felt FB.
The junction 112 between 2B and end wall 56B is beveled or rounded at 97. End wall 56B,
This bevel of 58B has been shown to help keep the air away from disturbing the movement of the web end as it engages the rope. Moreover, by deflecting the air jets 100, 102 by the curved edges 97, repair and maintenance of the dryer is enhanced. Referring to the operation of the blow box 40 of the preferred embodiment shown in FIG. 4, compressed air is supplied to the blow box 40 so that the air in the box 40 exits as an air curtain 46. In part, a local vacuum is induced in the vicinity of the branch pinch 18, thereby causing the web W to closely follow the felt F. As the web and felt move together toward the second dryer 14, a slight vacuum is created due to the arrangement of the dispersing wall 52, thereby providing a lower vacuum between the first and second dryers. Web W keeps away from felt. As the second dryer continues to rotate, the air dragged by the second dryer is diverted by the brush 64, thereby suppressing an increase in pressure at the junction holding portion 24 and further diverting the air. The resulting airflow is between the second dryer and the third dryer, a recess 2 near the felt and web.
It also helps to reduce the air pressure in 6. This negative pressure has a tendency to pull the web into tight compliance with the felt, which tendency is enhanced by providing holes 86 in the base wall 48 that direct the air curtain out of the recess 26, This helps to increase said negative pressure in the recess. If the web W is broken,
Wrapped around the first dryer 12, the diffuser wall 52 near the orifice 44 may be reduced by the air box 40 and the wrapped web that rotate on axis away from the first dryer 12. It is displaced from one dryer 12, thereby inhibiting any possibility of destroying the air box 40. Preferably, the air box 40 is normally mounted on a pivot such that the weight of the air box 40 is propelled to the position shown in FIG. Thus, if the web breaks, the thickness of the web wrapped around the first dryer 12 causes the air box 40 to rotate about the pivot 68 against the weight of the air box. Referring to the operation of the alternate embodiment of the present invention shown in FIG.
The first compartment 82 is supplied with compressed air, which flows through the orifice 44A as described with respect to the previous embodiment. However, some of the air in the first compartment 82 flows through the holes 86 in the first compartment 82 toward the opening 90 defined by the base wall 48A. Such an air flow passing through the opening 90 will tend to induce a local vacuum in the second compartment 84 so that some of the air near the converging nip 24A will enter the inlet 9A.
2, and flows into the second compartment 84, and then passes through the opening 90 and out of the recess 26A. Under some circumstances, if the local vacuum induced in the second compartment 84 is sufficient, all air passing between the outer periphery 22A of the second dryer 14A and the curved wall 50A will The installation of the brush seal 64 is unnecessary since it is turned rearward through the second compartment 84. Referring to the operation of the third embodiment of the present invention, a part of the compressed air is supplied to each of the first slots 96.
And the second slot 98, thereby causing the web edges to closely follow the respective felt edges. The present invention and the various embodiments described above overcome the difficulties associated with previous proposals, especially by using a compressed air source to create a negative pressure in the recess. Moreover, the present invention provides an air assisted transfer extending from the branch hold of the first dryer to the merger hold of the second dryer. In addition, the air exiting the orifice serves the purpose of deflecting all of the air which is dragged by the felt passing around the first dryer and which tends to increase the pressure in the recess. Therefore, the present invention provides a blow box of a simple configuration that enables high-speed web production by greatly enhancing the web-felt bond. It will be apparent to those skilled in the art that various alternatives and modifications can be made to the embodiments described above without departing from the spirit and scope of the invention as set forth in the appended claims. Good.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a portion of a typical dryer section showing the tendency of the web to move away from the felt. FIG. 2 illustrates one prior proposal for enhancing the bond between the web and the felt. FIG. 3 shows another prior proposal for reducing the tendency of the web to move away from the felt near the converging nip. FIG. 4 is a side sectional view of the blow box according to the present invention; FIG. 5 is a graph showing the degree of vacuum induced at various distances from the blow box orifice. FIG. 6 is a side sectional view of one alternate embodiment of the present invention. FIG. 7 is a blower having a first slot and a second slot disposed proximate a first end wall and a second end wall.
FIG. 4 is a perspective view of another embodiment of the present invention showing a box. FIG. 8 is a fragmentary perspective view of the blow box shown in FIG. 7 with the junction between the dispersing wall and the end wall beveled. [Explanation of Symbols] F ... Felt W ... Web 10 ... Dryer part 12 ... First dryer 14 ... Second dryer 16 ... Third dryer 18 ... Branch clamping part 20 ... First dryer surface 22 ... First dryer Outer perimeter 24 of the two dryers: Converging holding part 26 ... Recess 28 ... Converging holding part 30 ... Blow box 32 ... Compressed air 36 ... Air box 40 ... Blow box 42 ... Compressed air source 44 ... Orifice 46 ... Air flow 48 ... Base wall 50. Curved wall 52. Dispersion wall 54. Connection wall 56. First end wall 58. Second end wall 60. First plane 62. Second plane 64. Turning means 70. Point 74 ... Opening 76 ... Air flow 78 ... Contact point 80 ... Baffle 82 ... First compartment 84 ... Second compartment 86 ... Hole 90 ... Opening 92 ... Inlet 96 ... First slot 97 ... Curved edge 98 ... Second slots 100, 102 ... air flows 104, 10 6 ... web edges 108, 110 ... felt edge 112 ... joint

Claims (1)

(57) [Claims for Utility Model Registration] A first dryer (12), a second dryer (14), and a first bending direction around a cylindrical outer surface of the first dryer (12). And then suspended around a cylindrical outer surface of the second dryer (14) in a second direction of curvature opposite to the first direction of curvature and around the first dryer (12). Is transferred to the felt (F) which is conveyed around the second dryer (14), and the felt is a first felt which tangentially leaves the cylindrical outer surface of the first dryer (12). The linear contact point (78) and the felt are connected to the second dryer (1).
Felt (F), such as forming a branch clip (18) extending straight along a plane (62) between the second linear contact point tangentially meeting the cylindrical outer surface of (4). An extending plane (62) of the branch holding portion (18) of the felt from the first end portion which is close to and facing the felt (F) at the position of the first linear contact point (78). Extending along a plane (60) extending at an acute angle to the second end, spaced from the first end, with respect to the branch clip (18) of the felt. A first wall portion (52) gradually moving away from the felt along the moving direction of the felt, and the second dryer from one end connected to the second end of the first wall portion to the other end; A second wall (5) extending along and close to the cylindrical outer surface of (14).
0) and an opening at the first end of the first wall (52) to allow air to flow through the first linear contact points (7
8) a blow box (40) having a linear orifice (44) for blowing in a direction opposite to the direction of movement of the felt, whereby air blown from the linear orifice is provided. The part of the felt seated around the cylindrical outer surface of the first dryer after being sprayed onto the part of the first linear contact point (78) of the felt and the part of the blow box The wedge-shaped space formed between the first wall (52) and the first end is discharged in the direction of enlargement, and the felt (F) is formed outside the cylindrical shape of the first dryer (12). A web (W) on one of the surfaces facing the surface, whereby the web is carried by the felt and the felt is conveyed around the first dryer. And the cylinder of the first dryer Web dryer adapted to be sandwiched pressed between the outer surface.