Adjustable activity drainage box

Abstract

A process, and an apparatus, for improving sheet properties in the initial impingement zone of a paper making machine including a forming section, a forming fabric moving in the machine direction and a head box having a head box slice which delivers a stock jet onto the moving forming fabric. The scale and intensity of agitation within the stock is adjusted by adjusting some of the support elements beneath the forming fabric adjacent the head box slice so that they either contact, or do not contact, the machine side surface of the forming fabric and observing the effect, if any, that the adjustment has on the quality of the sheet product being made on the paper making machine. This technique is of use in a papermaking machine forming section having a single open surface forming fabric, in the initial open surface section of a so-called hybrid gap former having two superposed forming fabrics, and in the forming section of a two fabric papermaking machine.

1. An apparatus for improving sheet properties in a paper making machine including a an open surface forming section, at least one having a single forming fabric, the fabric having a machine side and a paper side, and moving in the machine direction, and a head box having a head box slice which delivers a stock jet onto the paper side of the at least one moving forming fabric, comprising in sequence in the machine direction:
 a) a first fixed support element and in contact with the machine side of the at least one forming fabric; 
 b) at least one drainage box provided with a foraminous support surfacesurfaces, said foraminous support surface includes at least one vertically adjustable support element and which is provided with support means for the first fixed element; 
 c) a last fixed support element, supported by a drainage box, in contact with the machine side of the at least one forming fabric, which together with the first fixed support element and the machine side of the at least one forming fabric defines a reference surface; and 
 d) the at least one drainage box having an independently controlled vertical adjustment means for the at least one vertically adjustable support element, which permits adjustment of the or each vertically adjustable element while the paper making machine is operating so as to move said at least one vertically adjustable support element into and out offof contact with the machine side of the forming fabric. 
 
     
     
       2. An apparatus according to  claim 1 , wherein the first fixed support element is adjacent to the head box slice. 
     
     
       3. An apparatus according to  claim 1  wherein the foraminous surface is supported by a plurality of drainage boxes in sequence. 
     
     
       4. An apparatus according to  claim 2  wherein the foraminous surface is supported by a plurality of drainage boxes in sequence. 
     
     
       5. An apparatus according to claim  1  3, wherein a first support and last support elements element in the machine direction in a first drainage box are is fixed, and both a first support and last support elements for a second drainage box immediately following in the machine direction are fixed. 
     
     
       6. An apparatus according to  claim 1 , wherein a first support and last support elements element in the machine direction in a first drainage box are is fixed, and both a first support and last support elements for a second drainage box immediately following in the machine direction are not fixed. 
     
     
       7. An apparatus according to  claim 1  wherein the papermaking machine including the forming section is chosen from the group consisting of:
 an open surface paper making machine having a single forming fabric; 
 a hybrid gap former paper making machine having two superposed forming fabrics in which at least that portion of the forming section adjacent the head box slice has one forming fabric having an open surface; and 
 a twin fabric papermaking machine having two forming fabrics each having a paper side and a machine side, in which the jet of stock is delivered onto the paper side of at least one of the two fabrics, and at least a plurality of support elements in contact with the machine side of at least one of the forming fabrics are adjustable. 
 
     
     
       8. An apparatus according to claim  1  3, including at least two three drainage boxes wherein a first support and last support elements element in the machine direction in a first one of the drainage box are boxes is fixed and both a first support and last support elements element for a second third one of the drainage box immediately boxes following in the machine direction are is fixed and all of the support elements for a second one of the drainage boxes are not fixed. 
     
     
       9. An apparatus according to claim 1, wherein the at least one drainage box which is provided with the foraminous support surface that includes the at least one vertically adjustable support element is provided with support means for the first fixed support element and the last fixed support element. 
     
     
       10. An apparatus according to claim 3, wherein there are at least two of the drainage boxes wherein a first support element in the machine direction in a first one of the drainage boxes is fixed and a first support element for a second one of the drainage boxes immediately following the first drainage box in the machine direction is fixed. 
     
     
       11. An apparatus according to claim 3, wherein at least three of the drainage boxes are provided, wherein a first support element in the machine direction in a first one of the drainage boxes is fixed, a first support element in the machine direction in a second one of the drainage boxes is fixed, and a support element for a third one of the drainage box following in the machine direction is fixed and all of the remaining support elements of the first and second drainage boxes are not fixed. 
     
     
       12. An apparatus according to claim 1, wherein the independently controlled vertical adjustment means for the at least one vertically adjustable support element which permits adjustment of the or each vertically adjustable element includes a pivoting arm having a first end connected to a pivot point and a second end connected to a link that is movable by rotation of a shaft, and a plurality of the pivoting arms are located under the or each vertically adjustable element. 
     
     
       13. An apparatus according to claim 1, wherein profiles of supporting surfaces of the or each adjustable support element and the fixed support elements are the same. 
     
     
       14. An apparatus according to claim 1, wherein profiles of supporting surfaces of the or each adjustable support element and the fixed support elements are not all the same.