Patent Publication Number: US-6210534-B1

Title: Trim squirt for a paper-making machine

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to paper-making machines, and, more particularly, to trim squirts for use in paper-making machines. 
     2. Description of the Related Art 
     Paper-making machines typically include a head box which discharges a fiber suspension stream with a known cross-sectional profile onto a wire in a fourdrinier section. The wire carries the fiber web to a forming section, where the fiber web is transferred from the wire to the forming section. The lateral side edges of the fiber web which is carried by the wire typically are of poor quality. Accordingly, it is common to discharge the fiber suspension from the head box onto the wire with a width which is wider than the working width of the forming section. The fiber web is trimmed in the fourdrinier section using a pair of trim squirts which are placed along respective lateral side edges of the fiber web. Each trim squirt discharges a water stream at a relatively high velocity to cut the lateral side edges from the fiber web. 
     It is important that a trim squirt provide a continuous cut of the fiber web as the fiber web travels past the trim squirt toward the forming section. If the fiber web is not continuously cut, the fiber web will normally tear when it is transported to the narrower width forming section. An intermittent pause in cutting can be caused by a pressure fluctuation or an air bubble in the pressurized water which is supplied to the nozzle cutter of the trim squirt. Conventional trim squirts typically provide a pressurized fluid directly from a pump or the like to the nozzle cutter of the trim squirt. The flow velocity of the water is therefore affected by pressure fluctuations associated with rotational speed fluctuations of the pump. It is therefore possible that the fiber web may intermittently not be cut, thereby possibly resulting in tearing of the fiber web. Moreover, no provisions are made to remove air bubbles from the pressurized water which can likewise result in the web intermittently not being cut. Such air bubbles can occur from agitation or turbulence of the pressurized water. 
     What is needed in the art is a trim squirt which operates at a more constant pressure and without air bubbles to thereby ensure that the fiber web is continuously cut. 
     SUMMARY OF THE INVENTION 
     The present invention provides a trim squirt which cuts the fiber web in an uninterrupted manner and with minimum pressure fluctuations. 
     The invention comprises, in one form thereof, a paper-making machine for making a fiber web, including a wire for carrying the fiber web. A trim squirt includes a nozzle cutter and an accumulator tank. The nozzle cutter is directed toward and transverse to the wire. The accumulator tank includes an inlet for receiving a pressurized fluid and an outlet fluidly connected with the nozzle cutter. The tank is structured and arranged to define an air attenuation pad therein. 
     An advantage of the present invention is that the fiber web is cut in an uninterrupted manner. 
     Another advantage is that pressure fluctuations within the tank, and thus flow velocity fluctuations at the nozzle cutter, are minimized. 
     Yet another advantage is that the fluid level within the tank can be easily controlled without the use of sensors, electronic controls, etc. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a schematic view of an embodiment of a paper-making machine of the present invention; and 
     FIG. 2 is side view of the accumulator tank shown in FIG.  1 . 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, there is shown a portion of an embodiment of a paper-making machine  10  of the present invention for making a fiber web. Paper-making machine  10  generally includes a fourdrinier wire  12  and a trim squirt  14 . 
     Wire  12  carries a fiber suspension web thereon and moves in a direction orthogonal to the drawing of FIG.  1 . Typically, wire  12  receives a fiber suspension with a known cross-sectional profile from a head box (not shown). Water in the fiber suspension drains through wire  12  as it is carried from the head box toward a forming section (not shown). Although trim squirt  14  is shown with reference to a fourdrinier wire  12 , it is also possible to position trim squirt  14  in a different part of paper-making machine  10 . Accordingly, the term “wire” is used herein in a generic sense to mean a continuous traveling surface within paper-making machine  10  which carries a fiber web, such as a water impermeable belt, felt or wire. Wire  12  typically is carried by a plurality of rotatable rolls (not shown). 
     Trim squirt  14  generally includes an accumulator tank  16  and a pair of nozzle cutters  18 . Each nozzle cutter  18  is positioned adjacent to a lateral side edge  20  of wire  12 . Each nozzle cutter  18  includes an interior nozzle configuration which jets a stream of water at the fiber web carried by wire  12  at a predetermined velocity, dependent upon a target delivery pressure. The water jet is directed toward the fiber web carried by wire  12  at an angle generally perpendicular to wire  12 . 
     Accumulator tank  16  (shown more specifically in FIG. 2) includes an inlet  22  for receiving a pressurized fluid from a fluid source such as a pump (not shown) via a fluid conduit  24 . A check valve  26  may be provided in fluid conduit  24  which allows fluid flow only in a direction toward tank  16 . Pressurized water flows through inlet  22  into a chamber  27 A within tank  16 . 
     Accumulator tank  16  also includes an outlet  28  which is fluidly connected with each of nozzle cutters  18  via fluid conduits  30 . Each of inlet  22  and outlet  28  are positioned in a bottom half of accumulator tank  16 . More particularly, in the embodiment shown, inlet  22  and outlet  28  are each positioned near a bottom  32  of accumulator tank  16 . Outlet  28  receives pressurized fluid from a chamber  27 B. Chamber  27 B is separated from chamber  27 A via an intermediate baffle  34 . Pressurized fluid flows through chamber  27 A, over the top of baffle  34 , and then through chamber  27 B. 
     Accumulator tank  16  also includes one or more drains  36  which are connected to respective drain lines  38 . A pair of shut-off valves  40  are used to control fluid flow through drain lines  38 , respectively. Each drain  36  is associated with a respective chamber  27 A or  27 B. Drains  36  may be connected with bottom  32  so that substantially all of the fluid within chambers  27 A and  27 B may be drained. 
     Accumulator tank  16  also includes a pipe  42  which extends downwardly from a top wall  44 . Pipe  42  has a lower end  46  which sets an approximate liquid level of the pressurized fluid within accumulator tank  16 , as will be described in more detail hereinafter. Lower end  46  of pipe  42  preferably is disposed above upper end  48  of baffle  34 . It is also possible for lower end  46  of pipe  42  to be disposed substantially coterminous with or slightly below upper end  48  of baffle  34 . Pipe  42  is exposed to ambient pressure at an end opposite from end  46 . In the embodiment shown, pipe  42  includes an overflow end  50  which is exposed to ambient pressure and which may discharge fluid to a drain  52  for recycling, etc. 
     Accumulator tank  16  has a height dimension of at least 15 inches and a diameter of at least 4 inches to provide a volume which is sufficient to define an air attenuation pad above the pressurized fluid, as will be described in more detail hereinafter. In the embodiment shown, accumulator tank  16  has a height of at least 30 inches and a diameter of at least 6 inches. Optional mounting tabs  54  may be attached to accumulator tank  16  for mounting with appropriate structure within paper-making machine  10 . For example, fasteners such as bolts may extend through holes  56  in tabs  54  and be threadingly engaged with corresponding threaded holes in a support structure of paper-making machine  10 . 
     During use, pressurized fluid flows through check valve  26  and fluid conduit  24  into chamber  27 A. The pressurized fluid flows in a generally upward direction through chamber  27 A and flows over the top of baffle  34 . When the liquid level within chambers  27 A and  27 B is below the lower end  46  of pipe  42 , only ambient pressure exists within accumulator tank  16  and the liquid level rises. When the liquid level rises past lower end  46  of pipe  42 , an air pocket is formed in the top of accumulator tank  16 . The liquid level will continue to rise until the pressure of the pressurized liquid being pumped into accumulator tank  16  equals the pressure of the air attenuation pad above the liquid at the top of accumulator  16 . Air bubbles within the pressurized fluid are allowed to bubble out of the fluid and into the air pad at the top of accumulator tank  16 . If the air pad becomes too large, the air simply escapes through pipe  42  to the ambient environment. The air attenuation pad also helps to reduce fluctuations in the pressure of the fluid which is transported out from outlet  28 . The pressurized fluid flows through chamber  27 B and through outlet  28  to nozzle cutters  18  for cutting the lateral side edges from the fiber web carried by wire  12 . 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.