CN1751154B - Forming fabric support elements for paper machines - Google Patents

Abstract

A fabric support element for a papermaking machine has improved fluid drainage means, comprising openings which can include flow-through vents. The element can comprise an impingement shoe for a forming section of a papermaking machine. The openings can be defined by a plurality of laminar segments, at least some of which define a paper side surface of the element, and which segments can be spaced apart by additional laminar segments or other spacing means. Laminar segments for use in the element, a method of constructing the element, and a papermaking machine, or a forming section thereof, including the element are also provided.

Description

Forming fabric support elements for paper machines

technical field

The invention relates to forming wire support elements for use in paper machines, segments for use in said elements, methods of manufacturing said elements, and paper machines or paper machine forming sections using said forming wire support elements.

Background technique

In the initial section of the forming section of a paper machine, an unsupported shot of high moisture content pulp is sprayed from a head box slice onto the surface of a moving forming wire. The unsupported shotcrete typically traverses a distance of about 6 cm to about 40 cm and then intimately contacts the surface of the forming wire at contact points. The contact angle α formed between the jet of the pulp and the plane of the forming wire at the point of contact is typically about 4° to 10°. It is known that an improved paper structure can be obtained by minimizing the angle α and the length of the unsupported free shot. As the angle α increases, the magnitude of the pressure exerted by the shotcrete on the surface of the forming wire also increases.

Contact angles greater than about 5° have generally been found to produce peak contact pressures which can cause paper impressions, low retention of papermaking particulates and fillers and plugging of the forming wire. Therefore, the angle α should be made as small as possible so that ideally the unsupported shot of pulp is in approximately tangential close contact with the forming wire.

As the unsupported length of the free pulp shot increases, its outside surface begins to split into ridges and wrinkles, which will eventually lead to changes in the basis weight of the paper. Furthermore, the finely dispersed fibers in the pulp begin to re-flocculate rapidly in the unsupported shotcrete prior to reaching the point of contact. Therefore, the unsupported pulp shot should be kept as short as possible to minimize these effects.

It is difficult to shorten the unsupported stock shot without increasing the said angle α due to the conflicting space requirements between the headbox sheet output lip and the adjoining upstream rolls such as breast rolls (central rolls) or forming rolls length. Even though the headbox sheet output lip can be positioned such that the angle α is very small and the free spray is almost tangential to the forming wire, it is trapped between the surface of the forming wire and the forming wire. Air in the small wedge-shaped spaces between the unsupported pulp shot surfaces is entrained into the pulp while forming foam which is detrimental to the paper structure.

Several methods have been proposed to overcome these difficulties. US Patent 3,440,136 to Nelson et al. discloses a method of avoiding air entrainment by evacuating air from the forming zone and flooding the zone with water. However, this approach has been found to be difficult to implement in practice. US Patent 4,734,164 to Irwin et al. discloses a forming plate for a single forming wire machine in which the first blade is slightly curved to allow the breast roll to be lowered slightly. The difficulty with this approach is that air is trapped in the thin wedge-shaped space between the shotcrete and the forming wire as it flows over the non-ventilated, solid surface of the curved first blade. The air is forced into the pulp as foam causing formation defects. U.S. Patent 4,802,954 to Malashenko discloses the placement of lead-in blades prior to the curved blade elements proposed by Irwin et al., which is said to reduce pumping by the forming wire into the grout between the shotcrete and the forming wire. The amount of fluid in the wedge-shaped space. However, the small wedge-shaped air space remains. The pressure in the space is controlled by a vacuum pump to reduce spraying disturbances. Ewald in U.S. Patent 5,084,138 solves the problem of excessive free shot length by using curved swivel bars instead of large diameter breast rolls and solid curved blades, but it does not avoid Air entrainment at the wedge between.

Fujiwara in US Patent 4,425,188 uses longitudinally spaced grooves in a twin wire forming plate to create cross-directional flow to realign fibers within an incipient web, thereby reducing machine direction fiber alignment. Improved removal of water was achieved by Wildfong et al. in US Patent 6,372,091 by using grooves in the surface of the formed plate.

However, although it is known that fluting the forming boards, also known as contact plates, provides an improvement in the final paper quality, the use of such grooves has been found to be problematic. Firstly, since no active measures are taken to quickly remove the fluid drained from the contact surface of the forming wire, it was found that these grooves are quickly filled with pulp and thus lose their beneficial effect considerably. Secondly, it has been found that these grooves can create a foiling effect between the machine side of the forming wire and the inside of the grooves, while creating sufficient levels of suction to cause deterioration of the paper quality. Furthermore, it is difficult, time consuming and thus expensive to manufacture precisely sized grooves in the typical ceramic surface of these inserts, and the integrity of the ceramic can be compromised by such machining processes.

The following terms have the following meanings. Other terms used herein have generally the same meanings as they are used in the paper industry.

The cross-machine direction (CD) is a direction generally in the plane of the paper and generally perpendicular to the machine direction (MD).

Downstream is the direction within the paper machine generally facing the roll of paper exiting the machine towards the final paper product.

A forming wire support element is any fixed element within a paper machine to which at least one paper machine forming wire is attached in sliding contact, including but not limited to plates, blades, foils and agitators in the forming section device, and the suction box cover (Uhle box cover) in the press section.

Laminar segments are relatively thin components having a thickness ranging from about 1 mm (0.04 inch) or less to about 25.4 mm (1 inch) or more that can be assembled in side-to-side relationship A forming wire support element of the desired width is thus composed. The layered segments are typically formed from ceramic or other wear resistant material.

The machine direction (MD) is the direction within a paper machine approximately parallel to the general direction of transport of the paper.

The machine side (MS) surface is the side of the forming wire or forming wire support elements opposite the paper side surface and not in contact with the paper.

The paper side (PS) surface is the side of the forming wire or forming wire support elements or that contacts or faces the paper that is made on and conveyed through the paper machine.

Upstream is generally facing in the direction of the headbox in the paper machine.

The vent pattern describes the presence of open channels passing from the paper-side surface of the support element to the machine-side surface of the support element, ie from the forming wire contact side to the opposite side, said channels being referred to herein as flow-through vents.

It has now been found that some of the aforementioned difficulties can be completely or substantially eliminated by the use of vents which pass completely through the contact plate and thus allow sufficient fluid to be removed efficiently to prevent those grooves from filling. These flow-through vents are open through from the paper-side surface of the contact plate to the machine-side surface of the contact plate, and as in the case of previously grooved surfaces such as defined by Wildfong et al. in U.S. Patent 6,372,091 Compared to that, a greater amount of fluid can be removed from the initial contact zone at the contact plate along with air that would otherwise be trapped between the forming wire and the pulp shot.

Furthermore, it has been found that these flow-through vents allow large variations in the contact angle of the pulp shot and the final position of the contact point without any appreciable adverse effect on the final paper quality. This result is very surprising because in the past a change of as little as half a degree from the optimal value of the contact angle of pulp could have a large detrimental effect on the paper properties with respect to paper impression, residue, formation . The invention thus allows a wider range of pulp jet contact angles than previous solutions.

It has also been found that these flow-through vents can be arranged very advantageously by constructing the contact plate from a plurality of relatively thin laminar segments, which are mounted together on suitable holding devices in the paper machine , so as to be substantially parallel to each other and contact each other, and point in the machine direction (MD) at a substantially constant angle. These laminar segments are preferably formed of a suitable material, such as ceramic, so as to have a machine-side surface suitable for mounting on said holding means, a paper-side surface facing said forming wire in use, an upstream surface (or leading edge) and a downstream surface (or trailing edge), and, in use, a substantially parallel lateral cooperating surface facing said cross-machine direction (CD). The surfaces of at least a first set of segments together define a forming wire contact surface that the contact plate is to use to support the forming wire. The surface may have any desired profile suitable primarily for the needs of papermaking. A second set of segments may be disposed between pairs of first segments at appropriate intervals along CD, the second set of segments may have a different PS surface profile than that of the first set of segments. Preferably said second set of segments is shaped so as to form openings in the forming wire contacting surface of said element and so as to define vents which will open from said PS surface up to said MS surface. Alternatively, the spacer means may only be integrally constructed on one or both lateral CD surfaces of said first set of segments, in which case the contact plate will substantially consist of only such first segments. It has been found that the spacer means, either constructed integrally with the first set of segments, or comprising a second segment, may be of suitable construction to optimize the removal of fluid and entrained air from the pulp blasting.

It has also been determined that a segmented forming wire support element for use in any part of a paper machine can be assembled using a plurality of at least first and second laminar segments which are shaped so as to be Mounted on suitable holding devices and placed as required in any forming, press or drying section of the paper machine. These first and second laminar segments are mounted on known holding means so as to be substantially parallel to each other and in contact with each other, and are directed substantially in the MD or at a constant angle thereto. The structure and configuration of these segments is as described above generally in relation to the contact plate, the PS surfaces of at least a first segment together defining the forming wire contacting surface for supporting the papermaking forming wire. The PS surfaces of at least the first and second segments are shaped so as to provide, when assembled, PS surfaces of the element having any desired profile suitable to satisfy mainly papermaking conditions. The second set of segments may be positioned between selected pairs of first segments at suitable intervals along the CD as spacing or contouring means to enable the definition of openings, which may, but need not, include drawing from all A vent opening from the PS surface of the element to the MS surface of the element. The PS surfaces of the second and first segments may be shaped to provide the assembled element with either or both of the desired MD and CD profiles. A third or fourth segment, or more, may also be used in combination with said first and second segments in the same manner.

The present invention aims at proposing a vented contact plate for a paper machine with a plurality of flow-through vents extending from the contoured upper surface of the contact plate to the lower surface of the contact plate .

The present invention aims at proposing a segmented forming wire support element for use in the contact zone of the forming section of a high speed paper machine, said element comprising a plurality of layered segments. The PS surfaces of the segments are shaped so as to provide the overall desired profile of the forming wire contact surface or PS of the element and, if desired, the vents through the element are located between selected laminar segments. Opening is limited.

Thus, a contact plate constructed in accordance with the present invention fulfills four main functions. First, the contact plates are used to support the forming wire as it enters the contact zone; and second, the contact plates are used to vent a significant amount of any air that is trapped in the In the wedge-shaped space between the surface of the forming wire and the surface of the pulp shot. Third, the contact plate allows drained water to be removed efficiently and quickly; fourth, the contact plate provides a previously unavailable tolerance for the location and contact angle of the contact point.

Furthermore, the present invention aims at proposing a stationary forming wire support element for a paper machine comprising a plurality of at least first and second relatively thin laminar segments.

Furthermore, the present invention intends to propose segments for use in contact plates or otherwise fixed forming wire support elements, such that the PS surfaces of at least some of said segments provide a contoured forming wire contacting surface of said elements and pass through the The vents of the elements may be defined by openings located between at least some of the segments. The segments are shaped such that the forming wire support elements can be mounted in a releasably fixed manner in suitable holding means.

Furthermore, the invention aims at proposing a forming section of a paper machine comprising a segmented forming wire support element comprising a plurality of flow-through vents as contact plates.

Furthermore, the invention aims at proposing a method of manufacturing such an element assembled from multiple segments.

Contents of the invention

Thus in a first embodiment of broad significance, the invention aims at proposing an air-permeable, segmented forming wire support element for use as a contact plate in the initial contact zone of the forming section of a paper machine.

The contact plate comprises a plurality of layered segments constructed and arranged on a common support means to be releasably secured in generally parallel, contacting relation to each other and to allow the forming wire to be attached to the segments The public PS forming wire moves in a sliding contact on the contact surface.

In an optional configuration of the contact plate, the laminar segments are identical in shape and may comprise spacer means which may, but need not, be integrally constructed with the laminar segments.

In a second optional configuration, said contact plate comprises at least a plurality of first and second laminar segments, wherein said first segment provides said PS forming fabric contact surface, and said each second segment No PS forming fabric contacting surfaces are provided, but instead they are positioned between any two of said segments or groups of two or more segments. The second segment is shaped so as to form vents between two adjacent segments and, if desired, additional openings on the PS surface of the element; these vents open through the PS surface of the contact plate to the MS surface of the contact plate and allow fluid and air entrained from the pulp shot to pass through the forming wire. Optionally, the aeration can be enhanced by means of a vacuum connected to the underside of the contact plate. Advantageously, said second segments may be hydrodynamically shaped to facilitate the removal of large volumes of fluid moving at relatively high speeds. The second segment substantially separates a portion of the first segment to form openings in the forming wire contacting surface of the contact plate. By suitably shaping the laminar segments, these openings can be directed at the MD at a desired angle. Preferably, these openings will be slotted and directed at the MD at an angle of about 2 to about 20 degrees. With the configuration of the contact plate, both the vent and the opening will be directed at the MD at the same angle.

In a third optional configuration, a third segment is provided and positioned as required between the selected first and second segments, the PS surface of the third segment having an appropriate profile for the intended application.

The detachable mounting of the segments can be effected by various known means such as T-slots or dovetail mounts. Alternatively or additionally, the segments may be provided with openings through which rods or cables may be threaded for multiple identical segments, eg as in US Patent 3,871,953 to Lee et al. By known means, the rods or cables may thus be fixed to appropriate end blocks on each side of the profiled portion.

Thus, the present invention aims at proposing a vented contact plate for use in a paper machine, which is positioned adjacent to the contact point where the pulp shot from the headbox sheet outlet comes into contact with the moving forming wire, said contact plate include:

(i) a leading edge, which is located upstream of said point of contact;

(ii) trailing edge;

(iii) a machine side surface adapted to be detachably secured to said paper machine by means of securing means; and

(iv) a paper side surface having a given cross-machine direction profile and a machine direction profile adapted to support said forming wire in sliding contact;

wherein the paper side surface includes a plurality of vents starting approximately adjacent the leading edge and terminating approximately adjacent the trailing edge while extending from the paper side surface of the contact plate to the machine side of the contact plate surface.

Preferably, the contoured PS surface of the contact plate between the leading edge and the trailing edge is substantially generally convex, but may be of any suitable configuration for the particular case. This may comprise a substantially circular convexly curved, constant radius surface, or a surface with an increasing radius of curvature towards the trailing edge, so that the shaped trailing edge may be substantially flat. When intended for use in other areas of the paper machine, ie not as a contact plate, the PS surface may be flat, grooved or otherwise contoured. This choice will depend on papermaking conditions in the field where it will be used.

In a second embodiment of broad significance, the invention aims at proposing a forming section of a paper machine having a machine direction and a cross-machine direction, said forming section comprising:

at least one forming wire moving in said machine direction;

a headbox comprising a headbox sheet-type outlet for supplying shot of the papermaking pulp which is in intimate contact with the first forming wire at a contact point at a contact angle;

a roll around which the first forming wire passes and which is located upstream of the headbox laminar output;

a forming section downstream of said contact point, said forming section comprising stationary support elements defining a forming wire path through which each forming wire passes;

Wherein at least one forming wire is provided with vented contact plates positioned adjacent to respective contact points of said pulp with each forming wire, each contact plate comprising:

(i) Frontier;

(ii) trailing edge;

(iii) a machine side surface adapted to be detachably secured to said paper machine by means of securing means; and

(iv) a paper side surface having a given cross-machine direction profile and a machine direction profile comprising a forming wire contacting surface adapted to support said forming wire in sliding contact;

wherein the paper side surface includes a plurality of vents beginning approximately adjacent to the leading edge and terminating approximately adjacent to the trailing edge and extending from the paper side surface of the contact plate to the machine side of the contact plate surface.

In a paper machine with two forming wires, it will generally be preferred that the two contact plates are identical, their contoured forming wire support surfaces having the same shape, however, for specific cases, the two contact plates , and their contoured forming wire support surfaces can be of various shapes.

In addition to their use as contact plates, the segmented forming wire support elements can be adapted for use in a variety of different positions within a paper machine, including as water removal blades or suction box covers.

In a third embodiment of broad significance, the invention aims at proposing a forming wire support element for use in a paper machine, comprising:

(i) Frontier;

(ii) trailing edge;

(iii) machine side surfaces adapted to be detachably secured to said paper machine by securing means; and

(iv) paper side surfaces having a given cross-machine direction profile and a machine direction profile which comprise a forming wire contacting surface adapted to support a forming wire of a paper machine in sliding contact; wherein

(a) said element comprises a plurality of at least first and second laminar segments;

(b) the surface profile of the forming wire contacting the paper side of the first laminar segment differs from the profile of the paper side surface of the second laminar segment; and

(c) at least some of said first and second laminar segments provide a predetermined profile of the surface of the forming wire contacting paper side of said element.

In a fourth embodiment of its broadest meaning, the invention aims at proposing a papermaking machine having a machine direction and a cross-machine direction comprising:

a papermaking forming wire moving in said machine direction;

A forming wire support element comprising:

(i) Frontier;

(ii) trailing edge;

(iii) a machine side surface adapted to be detachably secured to said paper machine by means of securing means; and

(iv) a paper side surface having a given cross-machine direction profile and a machine direction profile comprising a forming wire contacting surface adapted to support said papermaking forming wire in sliding contact; wherein

(a) said element comprises a plurality of at least first and second laminar segments;

(b) the paper-side surface profile of the first laminar segment differs from the paper-side surface profile of the second laminar segment; and

(c) at least some of said first laminar segments provide a predetermined profile of the surface of the forming wire contacting paper side of said element.

In a fifth embodiment in its broadest sense, the invention aims at proposing a segment, a plurality of which can be fixed detachably to form a fixed forming wire support element for supporting a forming wire of a moving paper machine, such that the PS surfaces of at least some of the segments provide a contoured PS surface of the element in the MD direction, and flow-through vents through the element are defined by spaces between at least some of the segments, and may is further defined by spacer means to provide the CD and MD profiles of the element.

When the forming wire support element is used as a contact plate, it has been found to be advantageous that the leading edge of the flow-through vent has a generally convexly curved shape and that the trailing edge of the vent has a corresponding generally concavely curved shape. This shape has been found to be helpful in controlling the discharge of large volumes of fluid through the forming wire in the contact zone.

Furthermore, it has been found that the configuration of contact plates or other fixed forming wire support elements from multiple segments allows the use of hard and wear-resistant materials such as ceramics as complex shapes without problems associated with grinding such complex shapes and Problems associated with large-scale casting for the manufacture of such large part shapes.

In a sixth embodiment of its broadest meaning, the invention aims at proposing a method of manufacturing a stationary forming wire support element for supporting a forming wire of a moving paper machine within a paper machine, the method comprising the steps of:

(i) assembling a plurality of laminar segments in a spaced-apart and generally parallel configuration such that openings are defined between at least some adjacent pairs of said segments, the paper-side surfaces of at least some of said segments defining a composite paper a side surface, the moving forming wire is in sliding contact with the side surface of the composite paper;

(ii) Removably securing said segments to holding means on said paper machine by means of securing means such that said segments are generally parallel or pointing at a slight angle to said machine direction.

Description of drawings

The invention will now be described with reference to the accompanying drawings, in which:

Figure 1 shows a part of an open surface paper machine comprising a vented contact plate;

Figures 2 and 3 show parts of two different double forming wire paper machines;

Figures 4, 5 and 6 show fragments of each of three different embodiments according to the invention, respectively;

Figure 7 shows other configurations for the use of alternative profiles of lamellar segments of the present invention;

Figure 8 is an isometric view of a vented fixed support element according to an embodiment of the invention;

Fig. 9 is a top view of the structure of a segment according to an embodiment of the present invention.

Detailed ways

Figures 1 to 3 show only the parts of the paper machine necessary for understanding the invention.

Figure 1 shows the initial impingement zone of a paper machine comprising a vented impingement shoe according to the invention. The sheet delivery lips 1A and 1B of the headbox 10 convey the shot of the pulp 2 at the contact point I onto the PS surface 13 of the forming wire 3 . The forming wire 3 passes around rolls 6 , surrounds the vented contact plate 5 and then passes in the forming section attached to the first stationary support element 4 . The contact plate 5 is provided with a flow-through vent 20 forming a slot-shaped opening 22 in the PS surface of the contact plate 5 . Said contact plate 5 may be assembled from a plurality of relatively thin laminar segments and detachably fixed to suitable mounting means (not shown) on a discharge box (not shown). Alternatively, the contact plate 5 may consist of a single unitary structure comprising a plurality of flow-through vents 20 .

Since the moving forming wire 3 and the pulp shot 2 converge and meet at a contact angle α, there The air 8 in the wedge-shaped space between is captured and enters the forming wire 3. The air, together with some liquid in the forming wire at that point, passes through the PS surface 16 of the contact plate 5, through the MS surface 23 of the forming wire 3 into the flow-through vent 20, and includes the entrained air 8 is discharged through the MS surface 18 of the vented contact plate 5. The various structures and functions of the flow-through vent 20 will be described in more detail below with reference to FIGS. 4 , 5 , and 6 . Said vent 20 forms an opening 22 , which may be slot-shaped as shown in FIG. 1 , on the PS surface 16 of the contact plate 5 , starting close to the leading edge 12 and ending close to the trailing edge 14 .

In this configuration, it is possible to maintain the contact angle α close to zero, since the rolls 6 can be placed away from the path of the forming wire 3, and since the vented contact plate 5 takes up less space than said rolls 6, And the unsupported length of the shotcrete 2 is significantly reduced. Furthermore, by means of the flow-through vents 20, the entire or substantial amount of any entrained air 8 quickly passes along with the liquid expelled over the MS surface 18 of the vent-type contact plate 5, and said air 8 is thus vented within the forming portion. Prevents interference with the pulp forming process.

The depth of the openings 22 may also increase within the contoured PS surface 16 towards the trailing edge 14 of the vented contact plate 5, as explained in detail below with reference to FIG. 6, to allow additional liquid and entrained air to escape.

Figures 2 and 3 show the initial contact zone of a paper machine with two forming wires and employing two vented contact plates 51 and 52 according to the invention. In illustrating these two figures, the terms "upper" and "lower" simply refer to the directions shown, although in practice, in double forming wire machines, the forming sections are often oriented vertically, or at some angle direction. The vented contact plates 51 and 52 comprise flow-through vents 120 forming slot-shaped openings 122 in the PS surface.

Figure 2 shows the contact area of a double forming wire machine, in which the contact point I of the shotcrete 2 on the lower forming wire 31 precedes the contact point I between the upper forming wire 32 and the PS surface carried on the lower forming wire 31. The point of contact J between the initial nets. The contact point I is located at the position where the lower surface 123 of the lower forming wire 31 is supported by the vented contact plate 51 . Similarly, the point of contact J is located where the PS surface 124 of the upper forming wire 32 is supported by the vented contact plate 52 . As the moving forming wire 31 converges with the stock shot 2, the wedge-shaped space between the lower surface 91 of the stock shot 2, the lower surface 101 of the headbox lip 1B and the PS surface 113 of the forming wire 31 Air 81 is captured and enters the forming wire 31 . The air 81, along with some liquid carried by the forming wire 31 at this point, flows through the MS surface 123 of the forming wire 31 into the vents 120 of the lower vented contact plate 51 and exits through the MS surface 118. The structure with respect to said lower forming wire 31 is thus substantially the same as that shown in FIG. 1 . Downstream of contact point I, the upper forming wire 32 converges at contact point J with the upper side 92 of the pulp shot 2 , which is being supported by the lower forming wire 31 . More air is trapped in the space 82 between the PS surface 112 of the upper forming wire 32 and the surface 92 of the pulp 2 . This additional air, as well as some liquid within the forming wire 32 , flows through the MS surface 124 of the forming wire 32 into the flow-through vent 120 and exits the contact plate 52 at the MS surface 119 .

FIG. 3 shows an alternative structure to FIG. 2 . The structure of the lower forming wire 31 is the same. The upper forming wire 32 converges with said pulp shot 2 at the same point as the lower forming wire 31 , approximately at the point of contact I. In relation to the upper forming wire 32, the air 82 is now trapped in the space enclosed by the upper surface 92 of the pulp shot, the PS surface 112 of the upper forming wire 32 and the upper surface 102 of the headbox lip 1A. Substantially all of the trapped air, together with some of the liquid in the two forming wires, passes through the MS surface 118 of the lower vented contact plate 51 and through the MS surface 119 of the vented contact plate 52 while passing through the flow-through vents 120 to discharge out.

In two of these double forming wire machines the two vented contact plates will often be identical and have the same convexly curved shape. However, in some cases it may be desirable to use two different vented contact plates which may have different convexly curved shapes. Alternatively, in other cases, a double forming wire machine may be provided with a single contact plate.

The vented contact plate as shown in any of Figures 1, 2 and 3, as described in detail below, may comprise a single unitary structure, or a plurality of layered segments mounted in generally parallel relationship.

Referring now to Figures 4, 5 and 6, three laminar segments 55, 65 and 75 of different configurations are shown, respectively. As mentioned above, these are suitable for use in a vented contact plate 5, or for other fixed forming wire support elements 80 (as shown in Figures 8 and 9). Referring first to FIG. 4 , layered segment 55 has leading edge 212 , trailing edge 214 , contoured PS surface 216 , and MS surface 218 . Openings 220 are provided at appropriate locations within the layered segments 55 through which fastening means such as rods or steel cables (not shown) can be passed to facilitate detachment of the plurality of layered segments 55 fixed to form the contact plate 5 . Further mounting means for the laminar segment 55 may be provided at its lower surface 218 , such as grooves 221 .

The PS surface 216 of the laminar segment 55 supports the forming wire and together provides the forming wire supporting PS surface 16 of the vented contact plate 5 as shown in FIG. 1 . Similarly, the MS surface 218 of the layered segments 55 together provides the MS surface 18 of the vented contact plate 5 .

Between adjacent pairs of lamellar segments 55, accessory segments 56, 57, 58 are arranged. These serve two purposes, firstly, to provide spacing by pushing partially adjacent laminar segments 55, and secondly to define the structure of the vent 20 passing through from the PS surface 16 to the MS surface of said vented contact plate 5. 18. The accessory segments 56 , 57 , 58 may comprise spacer segments, or alternatively all or some of them may be integrally constructed with the laminar segment 55 . As shown in FIG. 4 , a vent leading edge 258 is defined by each of the appendage segments 56 and 57 , and a vent trailing edge 259 is defined by each of the appendage segments 57 and 58 . The vent leading edge 258 may be of any suitable configuration, but is preferably regularly or irregularly sloped in a direction towards the MS surface 218 to define an obtuse angle β or δ with the downstream portion of the MS surface 218 .

Referring to FIG. 5 , laminar segment 65 has substantially the same structure as laminar segment 55 shown in FIG. 4 . However, appendage segments 265, 266 and 267 together define a generally curved vent 20; the rear edge 269 of the first vent 20 is defined by the generally concavely curved appendage segment 266, the and trailing edge 269 are generally concave and convexly curved, respectively.

PS surface 260 of satellite segments 255, 256 and 257 or 265, 266 and 267 may have any suitable structure. They may provide the forming wire support PS surface 16 of the vented contact plate 5 , for example as shown with respect to the appendage segments 255 and 257 , and 265 and 267 . Optionally, as shown in FIG. 6 , the PS surfaces 260 of the subsidiary segments 276 and 277 do not extend to the forming wire support PS surface 16 of the vented contact plate 5 and together define openings 22 which are formed in each laminar segment. Additional drainage of liquid and entrained air 8 is provided at the rear edge 214 of the layered segment 75 which defines the rear edge 14 of the vented contact plate 5 .

In addition, as will be understood in detail with reference to Figures 7A to 7D, third laminar segments may be provided whose paper-side surface partially provides the paper-side surface 16 of the fixed forming wire support element and has a suitable structure, such as a shallow "V" ” shape, thereby imparting a stirring effect to the pulp 2 carried on the forming wire 3.

Referring to Figure 7A, the fixed forming wire support element 180 includes first and second laminar segments 85A and 85B. The first laminar segments 85A are respectively mounted substantially parallel to each other at a preselected small angle θ with respect to the MD, and at an angled manner to the substantially parallel second laminar segments at an imaginary intersection line 181 along the CD. 85B is adjacent. Between said first and second laminar segments 85A and 85B, third and fourth laminar segments 86A and 86B are mounted in the same manner, each having a different The PS surface profiles of the segments 85A and 85B are simultaneously removably secured to the subassembly of the element 180 by means of mounting means (not shown). End blocks 182 and 183 are provided at lateral edges 241 and 251 of said element 180 .

Referring to Figure 7B, three examples of alternative configurations for the laminar segments used in this embodiment are shown, while showing differences in the PS surface. Thus, the PS surface profile of the first laminar segment 185A comprises a shallow "V" shape, the PS surface of the second laminar segment 285A comprises a darker "V" shape, and the PS surface of the third laminar segment 385A is generally flat. of.

Fig. 7C shows a schematic top view of grouped layered segments for said element 180 as shown in Fig. 7B. In this view, laminar segment 385A is optionally spaced apart from laminar segments 185A and 285A. However, depending on the intended use of the element 180, a third layered segment having any PS surface profile of the layered segments 185A, 285A, 385A, etc. like fragments are used in combination.

Figure 7D shows a fixed forming wire support element 280 with an optional configuration in which the front laminar segments 85A, 86A are mounted at an angle θ1 with respect to the CD, while the rear laminar segments 85B, 86B are mounted at an angle θ ₁ relative to the CD. The anterior segment is contiguously contiguous at intersection line 281 and mounted at an angle 2θ ₁ relative to CD. End blocks 282 and 283 are provided at lateral edges 242 and 243, respectively. Although FIG. 7D shows the use of two sets of laminar segments, it will be appreciated that laminar segments 86A and 86B may be replaced by segments having various structural combinations, for example, as shown in the schematic view of FIG. 7C , which is Depending on the intended use of the element 280 .

Referring to Figure 8, there is shown in isometric view a vented fixed forming wire support element 80, which is intended to be used in any of a variety of different locations within a papermaking machine. The element 80 includes a plurality of laminar segments 85, which may be any of the configurations of the laminar segments 55, 65 and 75 shown in Figures 4, 5 and 6, respectively, or other suitable configurations. Selected laminar segments 85 are pushed into spaced apart relationship by second, third, and fourth subsidiary laminar segments, collectively designated laminar Segments 86, which may include isolated segments of the structure of subsidiary segments 56, 57 and 58 (FIG. 4), or 265, 266 and 267 (FIG. 5), or 275, 276, 277 (FIG. 6), or any other suitable structure. Alternatively, the accessory segment 86 may be of any suitable construction and may be integrally constructed with the laminar segment 85 as shown. The laminar segments 86 and 86 are removably secured by suitable mounting means such as rods 88 and T-slots 89 to a subassembly 87 (details not shown), which in turn are secured to preselected location. The rods 88 pass through openings 220 in each lamellar segment 85 , the rods 88 being detachably secured adjacent the lateral edges 24 , 25 of the elements 80 . Appropriately shaped end pieces, such as end pieces 182, 183 as shown in FIG. 7A, or end pieces 282, 283 as shown in FIG. This facilitates the fixing of the laminar segments 85 in place within the structure of the element 80 .

As can be clearly seen from Figure 9, the laminar segments 85 are detachably secured in a generally parallel relationship to each other, while generally in the MD direction but at an angle Θ relative to the MD. The angle θ is preferably in the range of about 2 degrees to about 20 degrees.

In operation, a predetermined number of laminar segments of desired configuration, such as laminar segment 85, may be aligned to form segmented forming wire support element 80, and mounted to subassembly 87 as shown in FIGS. 8 and 9, so that Said subassembly 87, in turn, is mounted in the desired position on the paper machine by suitable means (not shown) to support the forming wire of the paper machine in that position. The first laminar segment 85 may be separated as desired by second, third and fourth subsidiary laminar segments such as 56, 57 and 58 (FIG. 4), or 275, 276 and 277 ( 5), or by grouping other suitably shaped layered segments. The number, shape and position of the incidental or additional laminar segments will be determined by prevailing papermaking conditions.

The PS surface profile of element 80 can thus be shaped to produce the desired beneficial effect within the pulp or initial fabric carried on the forming wire. For example, the PS surface may be grooved in the manner previously described, or it may have an MD profile such as a shallow "V" shape, or it may be generally flat. The PS shape of the surface is determined by the appropriate selection of the laminar segments used to assemble the forming wire support element 80 . It is possible, but not necessary, to provide a flow-through vent 120 .

The layered segments 55, 65, 75 or 85 of the present invention are preferably made of wear resistant material such as ceramic or high density polyethylene. If the second, third and fourth layer segments (56, 57 and 58, etc.) Fragments are made of different materials.

Claims (18)

1. aeration type contact plate that is used in the paper machine, it is adjacent to the contact point that touches on the mobile forming net from the paper pulp whitewashing of head box chip delivery outlet ejection and settles; Described contact plate comprises:

(i) forward position, it is positioned at the upstream of described contact point;

Edge (ii);

(iii) machine side surface, it is suitable for being removably fixed to described paper machine by fixture; And

(iv) paper side surface, it has given machine direction profile and the machine direction profile of traversing that is suitable for supporting with sliding contacting mode described forming net;

Wherein, described paper side surface comprises a plurality of blow vents, they begin from contiguous described forward position roughly and roughly contiguous described back along and stop, extend machine side surface from the paper side surface of described contact plate simultaneously up to described contact plate.

2. aeration type contact plate as claimed in claim 1, it is characterized in that, described a plurality of blow vent is arranged between a plurality of stratiform fragments with forming net contact paper side surface, described forming net contact paper side surface provides the paper side surface of described contact plate together, and described a plurality of stratiform fragment is suitable for removably being fixed by fixture, and is spaced apart device and is forced at interval spaced relationship.

3. aeration type contact plate as claimed in claim 2 is characterized in that, at least some described escapements and at least some layered fragments constitute one.

4. aeration type contact plate as claimed in claim 1, it is characterized in that, described a plurality of blow vent is arranged between a plurality of first stratiform fragments and a plurality of second stratiform fragment at least, each described first stratiform fragment has forming net contact paper side surface, it provides the paper side surface of described contact plate, and described forming net moves on described paper side surface; At least some described second stratiform fragments do not comprise the forming net contact surface and are applicable to and are placed between the first selected stratiform fragment; The described first and second stratiform fragments are applicable to that the device that is fixed is removably fixing, and are spaced apart device and are forced into the each interval spaced relationship.

5. aeration type contact plate as claimed in claim 4 is characterized in that, each first stratiform fragment has the first paper side surface profile, and each second stratiform fragment has the second paper side surface profile that is different from the described first paper side surface profile.

6. aeration type contact plate as claimed in claim 4 is characterized in that, at least some described second stratiform fragments roughly provide the structure of described a plurality of blow vents.

7. aeration type contact plate as claimed in claim 4 is characterized in that, described escapement comprises at least some described second stratiform fragments.

8. shaped portion that is used for having machine direction and traverses the paper machine of machine direction, it comprises:

The forming net that at least one moves along described machine direction;

Head box, it comprises the head box chip delivery outlet of the whitewashing that provides paper making pulp, described paper making pulp is sentenced a contact angle at contact point and is closely touched on first forming net;

Roller, described first forming net passes through around described roller, and described roller is positioned at the upstream of described head box chip delivery outlet;

Shaped portion, it is positioned at the downstream of described contact point, and described shaped portion comprises the static supporting member that limits footpath, shaping networking, and each forming net passes through through described forming net path;

Wherein, at least one forming net is provided with the aeration type contact plate, and it is adjacent to described paper pulp and the contacted corresponding contact point of each forming net is settled, and each contact plate comprises:

(i) forward position;

Edge (ii);

(iii) machine side surface, it is suitable for being removably fixed to described paper machine by fixture; And

(iv) paper side surface, it has given machine direction profile and the machine direction profile of traversing, and they comprise and are applicable to the forming net contact surface that supports described forming net with sliding contacting mode;

Wherein said paper side surface comprises a plurality of blow vents, their roughly contiguous described forward positions and begin and roughly contiguous described back along and stop, and extend machine side surface up to described contact plate from the paper side surface of described contact plate.

9. the shaped portion that is used for paper machine as claimed in claim 8 is characterized in that, for each contact plate, described a plurality of blow vents are arranged between a plurality of first stratiform fragments and a plurality of second fragment at least; Each described first stratiform fragment has the forming net contact surface, it provides the paper side surface of described contact plate, described forming net moves on described paper side surface, at least some described second fragments do not comprise the forming net contact surface and are applicable to and are positioned between selected each first stratiform fragment, the described first and second stratiform fragments are suitable for removably being fixed by fixture, and are forced into the each interval spaced relationship by escapement.

10. the shaped portion that is used for paper machine as claimed in claim 9, it is characterized in that, each first stratiform fragment has the first paper side surface profile, and each second stratiform fragment has the second paper side surface profile inequality with the described first paper side surface profile.

11. the shaped portion that is used for paper machine as claimed in claim 10 is characterized in that, described escapement comprises at least some described second stratiform fragments.

12. a forming net supporting member that is used in the paper machine, it comprises:

(i) forward position;

Edge (ii);

(iii) machine side surface, it is suitable for being removably fixed to described paper machine by fixture; And

(iv) paper side surface, it has given machine direction profile and the machine direction profile of traversing, and they comprise the forming net contact surface that is applicable to the forming net of sliding contacting mode supporting paper machine; Wherein

(a) described element comprises a plurality of at least the first and second stratiform fragments;

(b) the paper side surface profile of the forming net of described first stratiform fragment contact paper side surface profile and the described second stratiform fragment is inequality;

(c) at least some described first and second stratiform fragments provide the predetermined profile of the forming net contact paper side surface of described element; And

Wherein, described paper side surface comprises a plurality of blow vents, and described a plurality of blow vents are arranged between a plurality of first stratiform fragments and a plurality of second stratiform fragment at least; Each described first stratiform fragment has forming net contact paper side surface, it provides the paper side surface of described contact plate, described forming net moves on described paper side surface, described a plurality of second stratiform fragment does not provide the paper side surface of described contact plate, and be applicable to and be placed between selected each first stratiform fragment, the described first and second stratiform fragments are suitable for removably being fixed by fixture, and are forced into the each interval spaced relationship by escapement.

13. forming net supporting member as claimed in claim 12, it is characterized in that, each first stratiform fragment has the first paper side surface profile that comprises the forming net contact surface, and each second stratiform fragment has the second paper side surface profile inequality with the described first paper side surface profile.

14. forming net supporting member as claimed in claim 12 is characterized in that, described escapement comprises at least some described second stratiform fragments.

15. forming net supporting member as claimed in claim 12 is characterized in that, at least some described a plurality of blow vents also comprise V-shaped groove.

16. one kind has machine direction and traverses the paper machine of machine direction, it comprises:

The paper making forming net that moves along described machine direction;

The forming net supporting member, it comprises:

(i) forward position;

Edge (ii);

(iii) machine side surface, its device that is suitable for being fixed is removably fixed to described paper machine; And

(iv) paper side surface, it has given machine direction profile and the machine direction profile of traversing, and they comprise and are applicable to the forming net contact surface that supports described paper making forming net with sliding contacting mode; Wherein

(a) described element comprises a plurality of at least the first and second stratiform fragments;

(b) the paper side surface profile of the paper side surface profile of the described first stratiform fragment and the described second stratiform fragment is inequality;

(c) at least some described first stratiform fragments provide the predetermined profile of the forming net contact paper side surface of described element; And

Wherein, the paper side surface of described element comprises a plurality of blow vents, and they are arranged between at least some described first and second stratiform fragments, and the described first and second stratiform fragments are forced into the each interval spaced relationship by escapement.

17. forming net supporting member as claimed in claim 16 is characterized in that, each first stratiform fragment has the first paper side surface profile, and each second stratiform fragment has the second paper side surface profile inequality with the described first paper side surface profile.

18. forming net supporting member as claimed in claim 16 is characterized in that, described escapement comprises at least some described second stratiform fragments.

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