KR19990072503A - Expanded flow range edge flow control valve for use in a paper machine headbox - Google Patents

Abstract

Edge flow control valves in the edge flow tube of the tube bank in the headbox can be adjusted to optimize the fiber orientation of the paper produced in the papermaking process. The present invention utilizes a chamfer at the edge tube inlet to increase the maximum flow rate of the pulp through the edge tube and the edge flow control valve. The minimum flow range does not change, thus increasing the underlying flow range of the pulp through the edge flow control valve. Experiments in the laboratory showed that the maximum flow rate increased by more than 15% with the minimum flow rate unchanged. A chamfer tool with a stop collar for controlling the depth of cut is used to provide a chamfer for optimal performance at the inlet of each edge tube. According to the present invention, the paper produced in the papermaking process improves fiber orientation even when a higher flow rate is required at the edge of the head box.

Description

Edge flow control valve used to control the flow of the extended range in the paper machine headbox.

The present invention relates to an edge tube and an edge flow control valve provided in a tube bank of a paper machine headbox, wherein the edge tube and the edge flow control valve are used for the orientation of pulp fibers or the control of pulp fiber angles. do. More specifically, it relates to expanding the flow range of pulp fibers passing through the edge flow control valve.

The basic condition for any headbox as part of the paper machine used in paper production is to provide lateral uniformity to the pulp ejected from the headbox. When forming pulp sprayed from the headbox uniformly, it is preferable that fiber flocs and grains are not included in the pulp flow. In addition, the paper box headbox must operate continuously without substantially accumulation of dust, fibers or chemicals, and must have the capacity to meet the demand for high production speeds of modern paper machines.

Two methods to address the increasing stringent quality requirements for paper produced by paper machines are to uniformize the basis weight profile and fiber orientation profile to even finer grades. will be. The present invention relates to uniformity of fiber orientation. However, a uniform basis weight profile is also important for the final good paper formation, so some background explanation is needed for basis weight issues and applications.

Basis variation in the transverse direction can be classified into two classes, that is, wide bands and narrow bands. Wider band fluctuations are controlled by thermal and mechanical reactions of the headbox structure and by bending the slice lips. The slice area of a conventional paper machine headbox, generally known to those skilled in the art, consists of an apron floor or a slice body wall cooperating with a lower slice wall, which determines the opening of the slice, following the paper flow process of paper stock. When moving to the stage, the stock flows out of the headbox at the slice opening and is transferred over the forming wire held around the roll. A series of regulators or actuators positioned at regular intervals are located along the body wall extending upward from the slice body wall to incrementally adjust the slice openings. Regulators or actuators positioned at regular intervals may adjust the slice openings to move as small as 1/10000 inches by mechanically manipulating the slice lip of the lower extended body wall or upwardly extending body wall. In general, when such fluctuation is less than or equal to two times the actuator spacing, control of narrow band fluctuations is impossible. Unless there is a variation over two or more actuator positions, no mechanical control device is available to make the basis weight profile uniform. Narrow fluctuations are of particular interest in paper production, as narrow fluctuations can adversely affect not only runability but also production quality, especially in the coating and super gloss operations of the papermaking process.

An important goal was to reduce the basis weight profile variation very finely. Over the years, paper machinery manufacturers have gradually reduced the gap between the jack or slice-lip actuators used to mechanically control the slice-lip opening of the headbox through which the paper pulp flows on the way to the next part of the paper production. come. The earliest systems adjusted the center distance to 300 mm (adjustment of 300 mm centers). After a short time, a central spacing of 150 mm became the standard. It later dropped to 100 mm and more recently has been used for all important grades of paper, with a center spacing of 75 mm. Due to this close center spacing, paper makers or operators had to discuss significant shortcomings, namely that it is inconvenient to manually control many actuators (by moving one actuator, also by changing the position of two or more adjacent slices, correcting them). The range of basis weight response is influenced by the multiple actuator widths. In addition, without careful monitoring, the slice openings may be permanently deformed. Making basis weight adjustments using slice-lips is complex and inherently difficult to control.

Profile operations can be controlled using advanced computer control, but the results of quality are not always good. Serrated profile generally occurs. Mapping and trim measurement is a daily issue. In other words, on top of all this, the concept of bending slices for basis weight control is basically flawed.

Any change in slice lip position affects both the magnitude and direction of the adjacent velocity as well as the local velocity of the slice flow. The velocity in one region can be reduced, but the lateral flow to the adjacent region must be tolerated. As is generally known to those skilled in the art, the transverse flow of pulp adversely affects fiber orientation. Uniform fiber orientation, which is the core of the present invention, is one of the important objects in paper production, and therefore is a concept that will be discussed more fully below, and the bending of the slice-lips is clearly unacceptable. Ideally, the purpose of today's papermakers is to be able to control the basis weight profile independently of the fiber orientation profile control. The IV-MH® headbox, a concept product manufactured and marketed by Beloit, can independently control basis weight and fiber orientation. U.S. Patent 5,196,091 discloses a headbox device having a stock dilution conduit for basis weight control.

The headbox disclosed in US Pat. No. 5,196,091 employs essentially different methods for profiling control-flow concentrations. Basis weight is a function of concentration and slice opening. If the local concentration is changed instead of controlling the slice lip profile, the basis weight profile can also be controlled.

The method used in the headbox disclosed in US Pat. No. 5,196,091 is to control the local flow concentration instead of bending the slice-lips to control the transverse basis weight. In this way, the local basis weight is adjusted by increasing or decreasing the local flow concentration. The slice openings can be kept uniform, thus eliminating adverse effects on fiber orientation by eliminating the transverse flow of the headbox and complex control algorithms and eliminating the bending limits of conventional slice lips.

The headbox disclosed in US Pat. No. 5,196,091 provides an injection system that is used to control flowability to control lateral flow. The headbox disclosed in US Pat. No. 5,196,091 utilizes a tapered header of a unique shape to receive the pulp stock, followed by a 90 ° rotation of the flow of pulp stock in the machine direction for lateral flow distribution. The main purpose is a tube bank consisting of a distribution tube and a nozzle portion consisting of a plurality of Converflo® vanes or flexible sheets, which are inline with the tube bank to maintain high speed without changing the flow direction, which is a stable flow. Necessary for delivery and clean headbox action.

In the headbox disclosed in US Pat. No. 5,196,091, an individual injection tube is added to the tube bank. Typically, there is one injection tube per vertical row of headbox tubes, with each injection tube located between adjacent rows of vertical tubes. Each of these injection tubes meter low concentrations of white water flowing into the header immediately upstream of the adjacent headbox tubes. Low concentrations of flow flow directly into the adjacent tube. In this way, the transverse concentration of the machine as a result of the position of the injection tube and the low concentration flow can be controlled at a center distance of 35 mm or less. This length is half the distance between the centers of adjacent tube rows.

An important feature of Beloit's concept product, the IV-MH® headbox, is the structure of the tube bank. The concept product IV-MH® tube bank includes a series of tubes, each tube having a circular inlet, a suddenly expanding large diameter portion and a transition to a progressively rectangular outlet. Such a novel tube as shown in FIG. 4 is disclosed in US Pat. No. 5,196,091. Due to this structure, the flow of pulp is accelerated through the transition. Tubes of this structure generate a pressure drop to help achieve uniform lateral flow distribution. Abundant turbulence is generated for fiber dispersion, and the tube banks provide a uniform velocity profile in the nozzle section without transverse flow. In addition, Beloit's concept IV-MH® headbox optimizes the uniformity of the stock concentration by providing the ideal tube length. Through testing, it has been found that long tubes can form basis weight streaks. The short tube of the concept product IV-MH® headbox provides a much more uniform concentration profile.

In addition, a headbox such as disclosed in US Pat. No. 5,196,091 may feature a parabolic tapered header. This shape exactly matches the theoretical shape needed to equalize the pressure distribution across the width of the paper machine. As a result, there is a very uniform lateral flow distribution for good sheet quality.

Another feature of the concept product IV-MH® headbox is the inline flow path from the header through the tube bank and the slice openings while maintaining a high nozzle speed. This provides stable flow movement and clean headbox operation.

The nozzle part of Beloit's concept product IV-MH® headbox injection system is divided into a plurality of channels, each of which is separated by a flexible sheet. Such sheets control fine scale turbulence and maintain layer purity. The concept product IV-MH® delivers exceptionally low turbulence intensity at the outlet of the headbox. This low density with great stability is important for high speed operation. One nozzle portion using such a flexible sheet is disclosed in US Pat. No. 3,607,625 to Beloit Corporation. Such flexible sheets are sold under the trade name Converflo® from Beloit. The high flow stability due to the combination of the concept product IV-MH® headbox tube bank and nozzle maintains individual flow in the slice opening, resulting in large desirable profile control.

Another feature of Beloit's concept product, the IV-MH® headbox injection system, is that the concentration changes, while the flow through the headbox does not change. This eliminates the possibility of lateral flow occurring at the nozzle, making it possible to profile basis weight without creating fiber orientation problems. As described earlier, fiber orientation is another factor in meeting stringent quality requirements in paper production. Basis weight issues are recognized and addressed through the dilution control system of IV-MH (registered trademark), Belote's concept product, such as disclosed in US Pat. No. 5,196,091. The problem of fiber orientation is at the heart of the present invention.

As mentioned above, the second issue in paper production required in modern papermaking is fiber orientation control. This depends heavily on the structure and operation of the headbox and is important for many grades of paper. The misalignment of the fibers can affect twisted warp on a linearboard, diagonal creases on the copy paper, and skewing in form.

The fiber orientation profile is more sensitive to headbox flow conditions than the basis weight profile. Misalignment of fibers can also be present when having a flat basis weight profile.

There are many factors that affect the fiber orientation profile. These factors include adjacent piping, header pressure distribution, headbox tube shape (particularly at the edge), transverse flow conditions, cleanliness, slice profile, stock spraying and molding on the wire. Basic instruments for controlling and measuring fiber orientation are available and are well recognized by those skilled in the art.

Beloit's concept product, the IV-MH® headbox, is designed to control the profile in a whole new way. Instead of relying on sliced lips as described above, the new concept product IV-MH® provides localized control flow concentrations. As mentioned above, this allows for easier and accurate control of basis weight profiles. In addition, fiber orientation, which is at the heart of the present invention, is controlled by opening or shutting off a large capacity edge flow control valve. Fiber orientation control is entirely independent of basis weight profile control.

The fiber orientation profile is affected by the flow at the edge of the tube bank. If there is a lack of flow or increase in flow at the edge of the tube bank, the fiber orientation is nonuniform. On the other hand, when the flow through the entire width of the headbox is nearly uniform, including at the edge, the fiber orientation profile is nearly uniform. For various grades of paper, it is desirable to control fiber orientation by controlling the flow rate through a particular edge tube of the tube bank. With the edge tube controlled, the papermakers have tools for controlling the fiber orientation directly and actively.

One method and apparatus for controlling twisting fiber orientation of a paper web is disclosed in US Pat. No. 4, 687,548. U. S. Patent No. 4, 687, 548 discloses a device in which a bypass flow of pulp suspension passes through an opposing lateral passage of a turbulence generator preceding the outlet channel or slice portion of the headbox. The correlation and size of the bypass flow is adjusted to control the twisting of the fiber orientation, where the bypass flow generates a lateral flow in the flow of the pulp suspension from the headbox, the velocity of which is the distortion of the fiber orientation. To compensate.

Another method and apparatus for controlling fiber orientation was previously used in Beloit's concept product IV-MH® headbox. Beloit's concept product, the IV-MH® headbox, achieves edge flow control by installing an edge flow control valve to regulate the flow in the edge tubes that form part of the tube bank. Beloit's driven element or flexible sheet following the tube bank resembles a series of parallel flags of fully open flow channels, which extend from one side of the flow channel to the other and all suspensions Flow through the flag.

However, the current forward edge orifice inlet of the edge flow tube in the tube bank of the concept product IV-MH® headbox limits the total flow rate to the edge flow control valve, limiting the amount of flow exiting the edge tube. It turns out to be limiting. Many field work experiences show that the current flow range of pulp through the edge flow control valve is not suitable for controlling fiber orientation or fiber angle. The current square edge orifice inlet and the problems associated with it will be discussed and described in more detail below with reference to a preferred embodiment of the present invention.

Poor arrangement or poor fiber orientation of the pulp fibers in the headbox affects the properties of the final paper to be produced. Edge tubes and edge flow control valves are used to control the orientation of the fibers. However, under current construction, under certain conditions sufficient flow is not provided through the edge tube and the edge flow control valve to compensate for poor fiber arrangement. What is needed is a new edge tube and edge flow control valve that can be used in modern headboxes to increase the flow through the edges of the tube banks in the headbox, requiring a large flow rate to compensate for poor fiber orientation. Even in the case of fiber orientation can be improved.

1 is a schematic side view of the paper machine head box shown with the side panel removed so that the inside of the head box is visible.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1 showing the tube sheet of the tube bank.

3 is a cross-sectional view taken along line III-III of FIG. 1 showing the driven element of the headbox shown in FIG.

4 is a cross-sectional view taken along line IV-IV of FIG. 2, showing a portion of a top view of the headbox shown in FIG.

5 is a partial plan view of the headbox of FIG. 1 with the top panel of the headbox removed to view the interior of the headbox;

6 is an enlarged view of the tubes C, M of FIG.

6A is an enlarged perspective view of one of the tubes shown in FIGS. 1-6.

7 is a graph showing the effect of the edge flow rate when the edge flow rate is related to the fiber orientation.

8 is a partial cross-sectional view of an edge tube and an edge flow control valve in accordance with the present invention.

9 is a schematic showing the preferred fiber orientation of a completely aligned paper.

9A is a schematic diagram showing fiber alignment when too much flow rate is discharged from an edge tube of a headbox such as the headbox of FIG.

9B is a schematic diagram illustrating fiber alignment when insufficient flow rate is discharged from an edge tube of a headbox such as the headbox of FIG.

10 is a partial cross-sectional view of the edge tube as shown in FIG. 8 with a chamfer tool used to provide a chamfer at the inlet in accordance with the present invention.

11 is a graph showing a correlation between a valve position and a flow rate when using an orifice inlet having a square edge in an edge tube.

12 is a graph showing the correlation between valve position and flow rate using an orifice inlet with a 0.040 inch chamfered edge in the edge tube.

<Explanation of symbols for main parts of drawing>

1: headbox

2: header

3: tube bank

8: tube

12, 13: edge tube

14: valve element

15: Edge flow control valve

A way to solve the increase in flow rate exiting the edge tube by increasing the amount of pulp flowing through the edge flow control valve of the tube bank in the headbox is to provide a chamfer at each inlet of the edge tube. The present invention increases the maximum flow rate through the edge flow control valve at least 15% or more without changing the minimum flow rate through the edge flow control valve. Accordingly, the present invention extends the flow range through the edge flow control valve of the headbox to improve fiber orientation when large flow rates are required.

Slice flow control is an important factor in obtaining a good profile of the paper machine. The aim is to adjust the headbox to produce a uniform discharge in the machine direction so that this property is maintained in the wire following the headbox without table disruption. The flat fiber orientation profile indicates no transverse flow.

Beloit's concept product, the IV-MH® headbox, uses an edge flow control valve. Such a valve may increase or decrease the stock flow in a row of tubes in a tube bank adjacent to the pondside or adjacent to the side of the headbox.

It has been found that the end-most tube has an immediate effect on fiber orientation without degrading the basis weight profile. Edge flow control valves allow papermakers to control fiber orientation by adjusting the stems of valves located at the top, front and back of the headbox. However, sometimes the wide open flow through the edge flow control valve does not provide enough flow to correct the problem of fiber misalignment.

Thus, a feature of the present invention is to increase the flow range of the edge flow control valve to improve the fiber orientation of the paper produced by the paper machine.

Another feature of the present invention is to improve uniform fiber orientation without adversely affecting the uniform basis weight profile.

Another feature of the present invention is to provide a flat fiber orientation profile to eliminate or substantially reduce fiber transverse flow.

These and other objects, features and advantages of the present invention will become apparent to those skilled in the art by describing the preferred embodiments with reference to the accompanying drawings.

According to the invention, the edge orifice tube inlet with the chamfer of the in-line edge tube is shown in FIG. 8. An edge tube with an chamfered edge orifice inlet increases, if necessary, the maximum flow rate of the pulp moving through the edge flow control valve, thereby improving the fiber orientation of the pulp flowing through the headbox.

Beloit's concept product IV-MH® headbox structure with an edge flow control valve is schematically shown and described in FIGS.

1 is a schematic diagram of a Beloit's concept product IV-MH (registered trademark) headbox 1. The head box 1 is divided into four parts. Looking from the left to the right of the drawing, the headbox 1 consists of a header 2 followed by a tube bank 3 and a driven element 4 in front of the slice opening 5, through which the slice opening The jet of pulp is directed from the headbox to the next stage of the papermaking process. The pulp suspension moves from the header 2 through the headbox 1 to the slice opening 5, which is shown by arrow 6. The headbox 1 causes the pulp suspension to flow from the pulp suspension tank 7 schematically shown in the lower left side of FIG. 1 through the header 2, from left to right as shown by arrow 6 in FIG. 1. The pulp suspension flows through the tube 8 of the tube bank 3, then between the driven elements 4 and through the slice opening 5 before exiting to the right. The outside of the pulp suspension flow passage of the headbox is shown as an edge 9 of the headbox 1.

2-4 show cross-sectional views of the interior of the headbox 1 along different cross-sectional lines.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, showing the tube sheet 10 of the tube bank 3 through the tube bank 3. The tube sheet 10 of FIG. 2 is a flat solid sheet material having a series of holes arranged up, down, left and right. Some of the holes in the tube sheet 10 of FIG. 2 are designed to assist in explaining the operation of the headbox 1 of FIG. 1, C, D, E, F, G, H, I, J, K, L, M, It is indicated by identification characters such as N and O. In FIG. 2, the structure at the center of the headbox 1 has been omitted as shown by the broken line in FIG. 2. In reality there are so many holes from left to right, the headbox 1 is much wider than its height.

3 is a view taken through the driven elements P, Q, R, S along the line III-III of FIG. Again, the structure at the center of the headbox 1 has been omitted, and the actual headbox 1 is much wider than its height.

4 is a cross-sectional view taken along the line IV-IV of FIG. 2.

Referring again to FIG. 2, each hole (C, D, E, F, G, H, I, J, K, L, M, N, O) and the other hole are the inlets of the individual metal tubes 8. . The tube 8 is shown longitudinally of the tube bank 3 in FIGS. 1 and 4. The pulp suspension flows through the tube 8 of the tube bank 3, not in the region between the tubes 8, which represents the solid structure of the tube bank 3. The entire pulp suspension flows through this tube 8.

The main purpose of the tube bank 3 is to rotate the pulp suspension 90 °, where the header 2 is connected with the tube 8 so that the pulp moves in the same direction (from left to right).

In FIG. 2, the tubes C, D, E, F, G on the left side of the tube bank 3 consist of a set of left edge tubes 8, which are not shown in FIG. 1. not. The tubes H, I, J, K, L on the right side of the tube bank 3 consist of a set of right edge tubes 8. The tube bank 3 is installed to control the flow of the pulp suspension in the edge tubes [(C to G) and (H to L)] of the tube bank 8. Each set 12, 13 of edge tubes has a separate edge flow control valve 14.

4 shows the edge tube more clearly. One left edge tube (C), one right edge tube (H), non-edge tubes (M, O), and edge tubes [(C to G) and (H to L) Edge flow control valves 14 for the two sets 12, 13, outflow channel 9, tube bank 3, and the tube from the distribution beam (not shown) of the header 2; The pulp suspension flowing through 8 is shown. In FIG. 4, which shows the tube bank 3, only a part of the tube 8 is shown between the edges 9 of the tube bank 3. 4 shows that the valve element 14, which controls the flow through the edge tubes ((C to G) and (H to L)), is a rod of semicircular shape (or half moon shape in cross section).

2 and 4, the left valve element 14 of FIG. 2, which is the same as the upper valve element 14 of FIG. 4 when viewed in connection with FIG. 4, has a left set 12 of edge tubes C-G. Rotate to extend across, hindering and reducing the flow of the pulp suspension through the left set 12 of edge tubes C through G. With regard to FIG. 4, the right valve element 14 of FIG. 2, which is identical to the lower valve element 14 of FIG. 4, has a half moon cross section that is completely outside of the right set 13 of the edge tubes H to L. Rotate so that the flow of pulp suspension through the right set 13 of edge tubes H to L flows without clogging. The two valve elements 14 can be blocked or opened to independently regulate the flow through each set 12, 13 of the edge tube [(C to G) or (H to L)]. The valve 14 may be initialized such that the two valves 14 are free or obstructing the flow of pulp suspension. The valve 14 is controlled by a control box 15 on the outside of the flow channel 9 shown in FIG. 4.

The driven element 4 will now be described with reference to FIGS. 1 and 3. The driven element 4 is a series of nearly parallel but converging individual driven elements (P, Q, R, S) that are, to some extent, flexible sheets mounted on a ferrule (although very hard), the right end of which is There is no deflection as shown in FIG. 1, the left end of which is supported by the tube bank 3. The function of the driven element is described in the background section of the present invention and is further described, for example, in lines 5 to 52 of line 75 of US Pat. No. 3,607,625, which is incorporated herein by reference.

The headbox 1 shown and described in FIGS. 1 to 6 is a valve 14 for regulating the flow in the edge tubes [(C to G) and (H to L)] which form part of the tube bank 3. To achieve edge flow control. A driven element 4 extending from one side of the flow channel to the other is shaped like a series of flags parallel to the unobstructed flow channel between the edges 9 located past the tube bank 3, all suspensions being Flow past the driven element.

Each of the edge tubes [(C to G) and (H to L)] of the tube bank 3 in the headbox is preferably the same size as the inner tubes M to O, and may be the same size if necessary. have. Each edge tube [(C to G) and (H to L)] and non-edge tube M to O have almost the same, or have the same diameter and length, so that there is almost the same flow resistance.

To further describe the components of the tube bank 3, reference is made to FIGS. 5 and 6. FIG. 5 is a partial plan view from which the upper panel of the head box is removed so that the inside of the head box shown in FIG. 1 can be seen. The pulp suspension flows through the header 2 into the tube 8 and the edge flow tube is labeled tube C. The flow channel is defined by the pond sidewall 16 on the left side of the headbox 1 and the pond sidewall (not shown) on the right side. A portion of the pulp flows through the left end of the header 2 and is recycled to the right end of the header 2 via a pipe (not shown). The left edge tube is shown with the left edge flow control valve 14. As also shown in FIG. 5, the control valve 14 is partially blocked, thereby suppressing the total flow through the tube C. FIG.

6 is an enlarged view of the tubes C and M of FIG. 4. As can be seen more clearly, Figure 6a shows the unique structure of the Beloit's concept product IV-MH® headbox. The tube shown in FIG. 6A shows a circular inlet 17, a large diameter 18 that suddenly expands in diameter, and a transition 19 that gradually becomes a rectangular outlet. Such tube structures are also disclosed in US Pat. No. 5,196,091, which is incorporated herein by reference. As explained, due to this unique structure, the flow is accelerated through the transition. The tube 8 of the tube bank 3 provides a uniform velocity profile to the nozzle portion 4 without the transverse flow of the pulp. As shown in FIG. 6, the left edge tube C of the set 12 of left edge tubes C through G is shown with the edge restraint control valve 14. As shown in FIG. 6, the control valve 14 is partially shut off, thereby reducing the total flow rate through the edge flow control valve 14. When the flow control valve 14 continues to open, the flow of pulp through the edge flow control valve 14 is complete. 6A shows well the inlet 22 of the prior art edge tube. As can be seen, the inlet 22 is a square edge structure. As described in the background section of the present invention, the square edge orifice inlet limits the amount of flow that travels through the edge tube, and as a result, cannot always compensate for misalignment of the fibers.

To help illustrate the effect of edge flow on fiber orientation, FIG. 7 is provided. FIG. 7 is a graph showing the fiber orientation profiles for two similar headboxes as shown in FIGS. Line 20 represents the fiber angle for the machine transverse position of the headbox in the headbox lacking edge flow. Line 21 represents the fiber angle for the headbox with a very uniform flow at the edge. The difference in this profile explains that the flow rate at the edge affects the fiber orientation. By controlling the flow rate through a particular edge tube, the papermaker actively controls the fiber orientation.

8 is a cross-sectional view of the edge tube 30 and the edge flow control valve 14 according to the present invention. As shown in FIG. 8, the difference of the edge tube 30 shown in FIG. 8 when compared to the edge tube described in FIGS. 1 to 6 is the inlet entering the edge tube. The chamfered inlet 31 of the edge tube 30 increases the flow through the edge flow control valve 14 as compared to the square edge orifice inlet of the current edge tube described in FIGS.

As shown and described in Figures 1-6, Beloit's concept product IV-MH (registered trademark) has recently been installed in paper machines used in paper mills on the West Coast of the United States. Various measurement techniques known to those skilled in the art have been employed to measure the fiber orientation of paper produced in paper machines. Because the fiber orientation of the paper is misaligned, the flow out of the edge tube of the headbox has proved insufficient. 9 schematically shows the preferred fiber orientation of the paper to be produced. 9A is a schematic diagram showing the alignment of the fibers when providing too much flow through the edge tube of the tube bank of the headbox. 9B is a schematic diagram showing the alignment of the fibers when providing insufficient flow rate through the edge tube of the tube bank of the headbox. As is generally known, fluids follow a path of least resistance. If there is too much fluid on the edge, the fluid will flow towards the center of the machine as shown in FIG. 9A. This phenomenon is referred to as inflow condition. If there is not enough fluid on the edge, the fluid will flow towards the edge of the machine as shown in FIG. 9B. This phenomenon is called an outflow condition. To help specify how pulp is discharged from the headbox, consider a free flowing river. In the absence of any external influences, the flow of the steel upper surface is fairly uniform and unobstructed. When the wind is blowing over the water or the boat is moving on the river, waves are generated on the surface of the water, thereby affecting the uniformly ordered flow of the river surface. The wave creates a transverse flow state on the steel surface such that the steel surface flows in a non-uniform and non-linear fashion. If there is too much flow at the edge of the headbox, or too little flow, a similar type of flow can be found in the flow of pulp exiting the headbox.

In the case of the IV-MH® headbox, which is a particular concept product installed and tested in the aforementioned paper mill, the fiber orientation is indicated as shown in FIG. 9B, ie outflow conditions are observed. When the edge flow control valve is fully open, insufficient flow is provided at the edge to produce the desired fiber orientation as shown in FIG. Accordingly, it is necessary for a large flow rate to pass through the edge flow control valve in the tube bank of the IV-MH (trademark) headbox, which is a specific concept product of Beloit.

Due to the problems arising in connection with the aforementioned concept product IV-MH (registered trademark) headbox, the subject of the present invention is required. Previously, in other prior art headboxes developed and developed prior to the invention of the concept product IV-MH® headbox, efforts have been made to increase the flow through the tubes of the tube banks. One concept was used to increase flow by providing a chamfer inlet in a standard tube. However, although the flow increases due to the chamfered tube, the chamfer is irreversible. In other words, it does not control the flow through the tubes in this prior art headbox. The edge flow control valve on the concept product IV-MH® headbox can control the flow through the edge tube. However, due to the square edge orifice inlet of the edge flow control valve, it did not always provide enough flow to the edge to compensate for misplacement of the fibers. According to the present invention, by combining the edge flow control valve and the addition of the chamfer inlet to the edge flow tube of the tube bank, the range of flow through the tube is increased while controlling the amount of flow through the tube. Have the ability.

The total flow rate through the edge flow control valve of the present invention is controlled by the edge control valve 14. By providing a chamfer inlet in the edge tube, with the control valve fully open, the flow through the edge flow control valve increases by at least 15%. These results are shown in FIGS. 11 and 12. A chamfer is provided at the inlet orifice of the edge tube of the IV-MH® headbox, which is a problem concept described above, to increase the flow through the edge flow control valve. As the flow through the tube increases, the fiber orientation in the outflow state shown in FIG. 9B changes to the fiber orientation as shown in FIG. 9.

A short description on the 11 and 12 shows the C _V curve using the chamfer edges without the flow control tube and the edge C _V curve and the chamfer edge tube and edge flow control valve with which the valve, respectively. C _V is the flow coefficient, for example C _V is 1 when 1 gallon per minute passes at a pressure drop of 1 psi. As can be seen, with the fully open, the flow through the edge tube and the edge flow control valve having the chamfer edge orifice inlet passes through the edge tube and the edge flow control valve provided with the standard square edge orifice inlet. 15-18% greater than flow.

The inlet of any tube placed in the tube bank makes a very significant contribution to the limit of flow through the tube bank or to total head loss. By providing a chamfer at the inlet of the edge tube of the tube bank, the maximum flow capacity through the edge flow control valve is greatly increased. When the edge flow control valve is set to 50 ° or less, the control valve is a control element for setting the flow, so that the chamfer increases the flow but does not adversely affect the minimum flow range. As mentioned above, in order to correct the inflow condition shown in FIG. 9A, it is often necessary to reduce the flow at the edge. However, when the edge flow control valve is 50 ° or more, the control valve is no longer a control element for setting the flow. Rather, the flow rate moving through the tube or through the edge flow control valve is the control element. As the pulp flows from the header to the tube bank, the chamfer inlet captures more pulp, resulting in an increase in the amount of pulp flowing through the edge tube.

As mentioned above, the fiber angle is greatly affected by the lack of flow or increase in flow at the edge of the headbox. An example of a lack of flow is when the flow rate at the edge is low, and the flow from the headbox flows toward the low flow rate area (the path with the least resistance) to fill the area (as shown in FIG. 9B). This produces a lateral flow that allows the fibers to be aligned at an acute angle towards the center of the flow in the machine direction, which can be corrected simply by opening the valve to allow more flow at the edge with an edge flow control valve. Can be. If the test results in a configuration as shown in FIG. 9A due to increased flow at the edge, the edge flow control valve may be re-adjusted to reduce flow at the edge. Although there are many parts or factors that can affect fiber angles, edge flow control valves are the most effective tool for adjusting fiber angles to produce a completely aligned paper. By appropriately adjusting the flow range through the edge flow control valve, the papermaker can correct the inflow and / or outflow conditions shown in FIGS. 9A and 9B, respectively.

The square edge orifice inlet of prior art edge tubes does not provide a flow range wide enough to compensate for fiber orientation when large flows are required at the edge. The chamfer according to the invention makes the inlet orifice of the edge tube appear larger than before, increasing the flow rate. The tube orifice inlet is highly responsible for the resistance through the valve, and the chamfer can adjust the valve spacing to control the minimum flow, while reducing its resistance and increasing the maximum flow through the edge flow control valve.

FIG. 10 shows a portion of the edge tube of FIG. 8 with a chamfer tool used to provide a chamfer in the edge tube. The chamfer inlet of this invention is made by the following method.

Since a typical edge tube has a tube wall 32 only 0.065 inches thick, it is optimal to have a chamfer of 0.04 inches. Also, conventional edge tubes are laser welded to tube bank plates or tube bank sheets. The optimal chamfer does not affect laser welding. A 0.04 inch chamfer provides a good safety factor for structural strength in tube bank plates and laser welding.

The chamfer tool 40 includes a 0.25 inch thick shank 41 for use with a right angle air tool (not shown). Considering the material used for the edge tube, the ideal cutting speed is 400 to 600 rpm. The cutting depth is controlled using the stop collar 42. The bottom of the stop collar 42 includes a Teflon washer 45 that is joined to protect the surface of the tube bank 3. The cutter 44 cuts the chip at the surface, so it must be cleaned after each tube is completed.

The cutter tool 40 forming the chamfer has the function of centering itself so that it does not damage the inner surface of the edge tube. Cutter 44 leaves a rising edge on top of the tube, which can be removed with 120 grit green silica carbide stone and emery paper. Burrs or knife edges left from the cutter 44 may be removed with a 1 inch scotchbrite drum. Chatter marks left from the chamfer tool 40 may be removed at about 82 ° to a grinding stone ground 1 inch in diameter.

The chamfer inlet of the edge tube is cut almost no more than 0.4 inches wide. Different cutting thicknesses can be set depending on the chamfer width. When the shim 45 is placed on the cutter 44 and the procedure of installing the cutter on the chamfer tube proceeds, point contact is made. The collar 42 is pressed strongly against the shim 45 so that two sets of screws (not shown) are tightened to the collar 42. Spot checks are made prior to chamfering each tube to ensure that the collar does not slip. The thickness of the shim varies with the size of the chamfer required. 5/8 stainless steel washers cut to exact thickness are excellent shims.

In order to provide as much flow as possible through the edge flow control valve, all edge tubes in the set of edge tubes located at the edge of the tube bank in the headbox must be provided with chamfers.

Apparatus for expanding the flow range of the edge flow control valve in the tube bank included in the headbox is described and illustrated in detail herein, but various modifications are possible without departing from the scope of the invention.

Edge tubes and edge flow control valves according to the present invention are used in modern headboxes to compensate for poor fiber orientation by increasing the flow rate through the edges of the tube banks in the headbox without changing the minimum range of flow rates. Fiber orientation can be improved even when high flow rates are required.

Claims (11)

A headbox assembly that extends a flow range of pulp moving through an edge tube of a tube bank in a headbox, A header for receiving the flow of pulp suspension, A tube bank having a plurality of tubes through which the pulp suspension flows and disposed following the headers; A nozzle portion having a flexible sheet through which the pulp suspension flows, and disposed after the tube bank, A slice opening disposed downstream of the nozzle portion, with a jet of pulp suspension directed from the headbox to the next process, A first edge tube constituting a portion of the plurality of tubes of the tube bank and positioned in the outermost edge region of the tube bank; A first edge flow control valve mutually coupled with the first edge tube to control the amount of pulp suspension moving through the first edge tube; A first edge orifice inlet with a chamfer that is part of the first edge tube, Paper produced in the papermaking process by extending the flow range of the pulp moving through the first edge tube due to the combination of the chamfered first edge orifice inlet and the first edge tube and the first edge flow control valve. Headbox assembly, characterized in that to improve the fiber orientation of the product. 2. The second edge tube of claim 1, further comprising: a second edge tube constituting a portion of the plurality of tubes of the tube bank, the second edge tube being positioned in an opposite outermost edge region of the tube bank and facing the first edge tube; A second edge flow control valve mutually coupled with the second edge tube to control the amount of pulp suspension moving through the second edge tube; And further comprising a second edge orifice inlet with a chamfer that is part of the second edge tube, Paper produced in the papermaking process by extending the flow range of pulp moving through the second edge tube due to the combination of the chamfered second edge orifice inlet, the second edge tube and the second edge flow control valve. Headbox assembly, characterized in that to improve the fiber orientation of the product. 3. The method of claim 2, wherein the first edge tube and the second edge tube are each individually part of a set of edge tubes, wherein one of the edge flow control valves controls the amount of pulp suspension traveling through a set of edge tubes. Another edge flow control valve controls the amount of pulp suspension moving through the other set of edge tubes, and each additional edge tube has an chamfered edge orifice inlet, wherein the chamfered edge orifice inlet And, the combination of the edge tube and the edge flow control valve extends the flow range of the pulp moving through the edge tube set to improve fiber orientation of the paper product produced in the papermaking process. . A processing method for processing an edge orifice inlet with a chamfer in an edge tube, wherein the edge tube is one of a plurality of tubes installed in a tube bank of a paper machine headbox through which pulp suspension flows, and the edge tube is produced in a papermaking process. Used to control the fiber orientation of paper products, Placing the shim on the cutter surface of the chamfering tool with the ability to center itself; Installing a cutter of the chamfer tool on an edge tube provided with a chamfer such that contact is made between the cutter and the edge tube; Pushing the collar of the chamfering tool against the shim strongly; Tightening the collar against the shim, Operating the cutter to rotate the shank of the chamfering tool to provide a chamfer edge in the edge tube, And said collar controls said depth of cut. 5. The chamfered edge orifice inlet processing method of claim 4, wherein the shank rotates at a speed of about 400 to 600 rpm. 5. The method of claim 4, further comprising a removing step of removing raised edges on top of the edge tube generated as a result of the chamfer cutting. 5. The method of claim 4, further comprising the step of eliminating the sharp edges left in the edge tube as a result of the chamfer cutting. 5. The method of claim 4, further comprising the step of removing any chatter marks generated by the chamfer tool during the chamfer cutting. 7. The method of claim 6 wherein the removing step is performed using 120 grit green silica carbide stone and abrasive paper. 8. The method of claim 7, wherein said removing step is performed using a 1 inch Scotchbright drum. 9. The method of claim 8, wherein said removing step is performed using an abrasive stone ground having a diameter of 1 inch at an angle of 82 degrees.