Abstract:
A screen apparatus includes a tank, a first cylidrical screen disposed inside the tank to form a first chamber, and a second cylidrical screen disposed outside the first cylindrical screen. The second cylindrical screen defines a second′ chamber facing the first cylindrical screen and having upper and lower portions communicating with an inlet portion, and second″ chamber. A connection member has a groove facing the second′ chamber at an intermediate portion of the second cylindrical screen, and a passage communicating with the groove for discharging a paper stock. The paper stock flows to the second′ chamber through the upper and lower portions. A part of the paper stock passing through the first and second cylindrical screens is discharged through first and second selection outlet portions, and a part of the paper stock not passing throught the first and second cylindrical screens is discharged through the passage.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a screen apparatus, and more particularly, to a screen apparatus which can increase a selecting processing amount of a paper stock. 
   2. Description of the Prior Art 
   There exists a screen apparatus in which a stirring member (e.g., foil, agitator or the like) is located outside of a cylindrical screen provided in a tank, a paper stock is allowed to flow from outside to inside of the screen, the paper stock is introduced to the screen from a portion of the screen located at one end surface and a portion thereof located at the other end surface, thereby solving or reducing “inconvenience that concentration becomes higher as the paper stock flows downstream of the screen” (e.g., see patent document 1).
     [Patent document 1 Publication (KOKAI)No.12-8287 (FIG.  4 )]   

   However, the above screen apparatus has a problem that there exists only a single cylindrical screen, and the screen apparatus is susceptible to improvement of a selecting processing amount of paper stock. 
   SUMMARY OF THE INVENTION 
   The present invention is achieved in view of the above problem, and it is an object of the invention to provide a screen apparatus which can increase a selecting processing amount of a paper stock. 
   To achieve the above object, a first aspect of the present invention provides a screen apparatus comprising: a tank having an inlet portion of a paper stock; a first selection outlet portion and a second selection outlet portion and receiving the paper stock; a first cylindrical screen whose one of end surfaces is closed and the other end surface is opened, the first cylindrical screen being provided at its side surface with a plurality of openings and being fixedly provided in the tank; a second cylindrical screen whose side surface is opposed to the side surface of the first cylindrical screen and whose both end surfaces are opened, the second cylindrical screen being provided at its side surface with a plurality of openings, the second cylindrical screen being fixedly provided in the tank; a first supporting member supported by one end of the second cylindrical screen and an inner wall of the tank; a second supporting member supported by the other end of the second cylindrical screen and an inner wall of the tank; wherein the second cylindrical screen is closed such that the paper stock enters the second cylindrical screen through the plurality of openings of the second cylindrical screen by the second supporting member and the first supporting member, an interior of the tank is divided into a first chamber and a second chamber by the first cylindrical screen, the second chamber is divided into a second′ chamber and a second″ chamber by the second cylindrical screen, the first chamber faces the first selection outlet portion, the second′ chamber faces an inlet portion of the paper stock, the second″ chamber faces the second selection outlet portion, the screen apparatus further comprises: a stirring member having stirring portions located inside of the second cylindrical screen and outside of the first cylindrical screen, the stirring member  3  being rotatably supported for stirring the paper stock in the second′ chamber; a connection member having an opening which is in communication with the second′ chamber formed between an inner side of the second cylindrical screen and an outer side of the first cylindrical screen, the connection member being mounted to the second cylindrical screen and in communication with the opening, the connection member having a passage for discharging out the paper stock, the connection member being provided in an intermediate portion of the second cylindrical screen; and a paper stock discharging passage which is in communication with the passage of the connection member and which has a passage for discharging the paper stock in the passage out from the tank. 
   According to a second aspect of the invention, in the first aspect, the connection member is a ring member which is in parallel to both end surfaces of the second cylindrical screen, and is located substantially at an intermediate portion between the both end surfaces, an outer side of the ring member swells toward an outer side of the second cylindrical screen, an inner side of the ring member forms a groove over the entire length of the ring member, a groove opening which is an opening of the groove is in communication with the paper stock discharging passage, the groove opening is provided in the wall. 
   According to a third aspect of the invention, in the first aspect, the inlet portion of the paper stock comprises: one inlet portion for a portion located at a position of one end surface formed between an inner side of the second cylindrical screen and an outer side of the first cylindrical screen; and the other inlet portion for a portion located at a position of the other end surface formed between the inner side of the second cylindrical screen and the outer side of the first cylindrical screen. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic front view of a screen apparatus according to an embodiment of the present invention. 
       FIG. 2  is a schematic sectional view of the screen apparatus shown in FIG.  1 . 
       FIG. 3  is a schematic sectional view taken along a  3 — 3  line in FIG.  2 . 
       FIG. 4  is a schematic sectional view taken along a  4 — 4  line in FIG.  3 . 
       FIG. 5  is a schematic sectional view taken along a  5 — 5  line in  FIG. 4   
       FIG. 6  is a schematic plan view of a stirring member incorporated in FIG.  1 . 
       FIG. 7  is a schematic sectional view taken along a  7 — 7  line in FIG.  6 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A screen apparatus of an embodiment of the present invention will be explained with reference to the drawings. 
   In  FIGS. 1  to  7 , a symbol A represents a screen apparatus. The screen apparatus A flows a paper stock from outside to inside of the screens  1  and  2 , thereby eliminating foreign matter from the paper stock. 
   A reference number  10  represents a tank which receives the paper stock. The tank  10  includes inlet portions  10   a  and  10   b  of the paper stock, a first selection outlet portion  10   c  and a second selection outlet portion  10   d.    
   The inlet portions of the paper stock are the inlet portions  10   a  and  10   b  of the paper stock for example. The inlet portions  10   a  and  10   b  of the paper stock are the inlet portion  10   a  which is an inlet to a portion located at one end surface formed between an inner side of the second cylindrical screen  2  and an outer side of the first cylindrical screen  1 , and the other inlet portion  10   b  which is an inlet to a portion located at the other end surface formed between the inner side of the second cylindrical screen  2  and the outer side of the first cylindrical screen  1 . 
   The inlet portions  10   a  and  10   b  of the paper stock are connected to an inlet pipe  10   e.    
   The first selection outlet portion  10   c  and the second selection outlet portion  10   d  are respectively connected to a first selection outlet pipe  10   f  and a second selection outlet pipe  10   g.    
   A reference number  1  represents the first cylindrical screen  1  fixed in the tank  10 . One of end surfaces of the first cylindrical screen  1  is closed, the other end surface thereof is opened. The first cylindrical screen  1  is provided at its side surface with a plurality of openings. The openings are slits, round holes or rod-like members which are annularly arranged. In the case of the screen, the openings are clearances formed between adjacent rod-like members. 
   A reference number  2  represents a second cylindrical screen fixed in the tank  10 . The second cylindrical screen  2  is located outside the first cylindrical screen  1 . A side surface of the second cylindrical screen  2  is opposed to a side surface of the first cylindrical screen  1 , and one end surface and the other end surface of the second cylindrical screen  2  are opened, and the side surface of the screen  2  is provided with a plurality of openings. Like the openings of the first cylindrical screen  1 , the openings of the second cylindrical screen  2  are slits, round holes or clearances formed between adjacent rod-like members. 
   As shown in  FIG. 4 , one of ends of the second cylindrical screen  2  and an inner wall  10   w  of the tank  10  are supported by a first supporting member  21 . The other end of the second cylindrical screen  2  and the inner wall  10   w  of the tank  10  are supported at positions closer to a second supporting member  22 . 
   The second cylindrical screen  2  is closed such that the paper stock enters the second cylindrical screen  2  through the plurality of openings of the second cylindrical screen  2  by the second supporting member  22  and the first supporting member  21  (see FIGS.  2  and  4 ).  FIG. 2  is a schematic sectional view taken along a  2 — 2  line in FIG.  3 . 
   Therefore, as shown in  FIG. 2 , an interior of the tank  10  is defined into a first chamber  1 A and a second chamber  1 B by the first cylindrical screen  1  in a flow of the paper stock. The second chamber  1 B is defined into a second′ chamber  1 B′ and a second″ chamber  1 B″ by the second cylindrical screen  2 . The first chamber  1 A communicates with the first selection outlet portion  10   c , the second′ chamber  1 B′ communicates with the inlet portions  10   a  and  10   b  of the paper stock, and the second″ chamber  1 B″ communicates with the second selection outlet portion  10   d.    
   A reference number  3  represents a stirring member having stirring portions  35  and  36  located inside of the second cylindrical screen  2  and outside of the first cylindrical screen  1 . The stirring member  3  is rotatably supported, and stirs the paper stock in the second′ chamber  1 B′. The stirring member  3  is rotated by a belt  31  from a motor (not shown), a pulley  32  and a rotation shaft  34  which passes through a closed portion  33  of the second cylindrical screen  2 . The stirring portions  35  and  36  of the stirring member  3  are mounted such as to be hung from a disk  37  mounted to the rotation shaft  34  for example. 
   The hanging stirring portions  35  and  36  are located between the first cylindrical screen  1  and the second cylindrical screen  2 . The stirring portion  35  is provided in the vicinity of the second cylindrical screen  2 , and the stirring portion  36  is provided in the vicinity of the first cylindrical screen  1 . 
   The stirring portions  35  and  36  are foils or agitator, and they are rotated in the vicinity of the first cylindrical screen  1  (or second cylindrical screen  2 ). When the stirring portions  35  and  36  are foils, a positive pressure is generated against the first cylindrical screen  1  (or second cylindrical screen  2 ) at a front portion of the foil, and a negative pressure is generated at a rear portion of the foil, thereby cleaning the first cylindrical screen  1  (or second cylindrical screen  2 ). 
   A reference number  4  represents a connection member having an opening  41  which comes into communication with the second′ chamber  1 B′ formed between the inner side of the second cylindrical screen  2  and the outer side of the first cylindrical screen  1 . The connection member  4  is mounted to the second cylindrical screen  2  and comes into communication with the opening  41 , includes a passage (e.g., later-described groove  42 ) through which the paper stock in the second′ chamber  1 B′ is discharged, and is provided in an intermediate portion of the second cylindrical screen  2 . 
   The connection member  4  is preferably a ring member which is in parallel to one of end surfaces and the other end surface of the second cylindrical screen  2 , and is located substantially at an intermediate portion between the one end surface and the other end surface. As shown in  FIGS. 4 and 5 , an outer side of the ring member swells toward an outer side of the second cylindrical screen  2 , an inner side of the ring member forms a groove  42  over the entire length (substantially entire periphery), a groove opening  44  which is an opening of the groove  42  is in communication with the paper stock discharging passage  5 , and the groove opening  44  is formed in the wall  43 . 
   A reference number  5  represents the paper stock discharging passage  5 . The paper stock discharging passage  5  is in communication with a passage of the connection member  4 , and includes a passage through which the paper stock in the passage, i.e., paper stock including great amount of foreign matter is discharged out from the tank  10 . 
   Therefore, if the paper stock is introduced into the first cylindrical screen  1  and the second cylindrical screen  2  from a portion located at the one end surface formed between the inner side of the second cylindrical screen  2  and the outer side of the first cylindrical screen  1  and from a portion located at the other end surface, respectively, the paper stock flows toward the connection member  4 , and during that time, good fiber passes through the first cylindrical screen  1  and the second cylindrical screen  2  and is introduced out from the tank  10  through the first selection outlet pipe  10   f  and the second selection outlet pipe  10   g , respectively. At that time, the first cylindrical screen  1  is cleaned by the stirring portion  36  of the stirring member  3  and the second cylindrical screen  2  is cleaned by the stirring portion  35  of the stirring member  3 , and clogging is prevented. 
   Further, paper stock having great amount of foreign matters which can not pass through the first cylindrical screen  1  and the second cylindrical screen  2  is effectively collected in the groove  42  formed over substantially the entire length of the inside of the ring member (connection member  4 ), and is ejected from the tank  10  through the groove opening  44  and the paper stock discharging passage  5 . 
   As a result, according to the screen apparatus A, the selecting processing amount of the paper stock is increased by the first cylindrical screen  1  and the second cylindrical screen  2  provided in the tank  10 , the paper stock is introduced to the first cylindrical screen  1  and the second cylindrical screen  2  from the portion located at the one end surface formed between the inner side of the second cylindrical screen  2  and the outer side of the first cylindrical screen  1  and from the portion located at the other end surface, so that it is possible to solve the “inconvenience that concentration is increased as the paper stock goes downstream of the screen”. 
   Further, the connection member  4 , which is a ring member, is in parallel to the one of end surfaces and the other end surface of the second cylindrical screen  2 , and is located substantially at an intermediate portion between the one end surface and the other end surface. The connection member  4  includes the wall  43  swelling outward. Therefore, paper stock having great amount of foreign matters which can not pass through the first cylindrical screen  1  and the second cylindrical screen  2  is effectively collected in the groove  42  formed over substantially the entire length of the inside of the ring member  4 , and dust-eliminating effect can be enhanced. 
   According to the first aspect of the present invention, the selecting processing amount of the paper stock is increased by the first cylindrical screen and the second cylindrical screen provided in the tank, the paper stock is introduced to the first cylindrical screen and the second cylindrical screen from the portion located at the one end surface formed between the inner side of the second cylindrical screen and the outer side of the first cylindrical screen and from the portion located at the other end surface, so that it is possible to solve the “inconvenience that concentration is increased as the paper stock goes downstream of the screen”. 
   According to the second aspect of the invention, in addition to the effect of the first aspect, the connection member is the ring member which is in parallel to the one of end surfaces and the other end surface of the second cylindrical screen, and is located substantially at an intermediate portion between the one end surface and the other end surface. The connection member includes the wall swelling outward. Therefore, paper stock having great amount of foreign matters which can not pass through the first cylindrical screen and the second cylindrical screen is effectively collected in the groove formed over substantially the entire length of the inside of the ring member, and dust-eliminating effect can be enhanced.