FR2488924A1 - POSITIVE IMPULSE DEHYDRATION BLADE FOR PAPER MACHINE OR THE LIKE - Google Patents

Abstract

THIS BLADE 22 IS INTENDED TO TAKE OFF FROM THE METAL CANVAS OF A PAPER MACHINE THE WET SHEET OF PAPER WHICH IS FORMING ON THIS CANVAS. THE BLADE SHOWS IN THE FRONT A CHAMFRAINED SURFACE 48 INCLINED UPWARDS AND IN THE DIRECTION OF THE CIRCULATION OF THE WET BAND CONSTITUTED BY THE METAL CANVAS AND THE FORMING SHEET OF PAPER. THE WATER SUCKED FROM THE BAND BY THE VACUUM TRANSMITTED THROUGH THE SLOTS 26 INTER-BLADES MEETS THIS INCLINED SURFACE 48 AND IS DELIVERED UP AND INTO THE BAND, APPLYING TO IT A POSITIVE IMPULSE THAT TENDS TAKE OFF THE SHEET OF PAPER FROM THE METAL CLOTH. AN ALTERNATE OF POSITIVE AND NEGATIVE PULSES (DIRECTED DOWNWARDS AND EXERCISED BY DEPRESSION) PERIODICALLY TAKES OFF THE FORMING SHEET FROM THE METAL CANVAS AND PROMOTES DEHYDRATION DOWNSTREAM. APPLICATION TO PAPER MACHINES OF THE FOURDRINIER TYPE.

Description

The present invention relates to a drying blade

  positive pulse geometry to facilitate extraction

a liquid from a wet band.

  In drying machines, especially in

  paper industry, in which it is customary to carry out dewatering operations at the wet end

  of a paper machine, continual

  looking for a dehydration process

more efficient.

  An example of a type of machine is the

  what these searches apply to the paper machine Four-

  drinier or flat-table that uses a suction box or dehydration to which a depression is applied for

  extracting the water from a set consisting of a metal fabric

  and by a sheet of material and forming a human band

  mide. A difficulty that manifests itself in a process of this type is that the material to be dehydrated accumulates in the form of a mud on the wire cloth and that, as the assembly composed of the cloth and the wet material sheet progresses along the machine,

  it tends to compress or compress or become entangled

  v8trer. This compacting effect makes the extraction of water more difficult. This disadvantage is further accentuated when it is considered that the vacuum is applied at several distinct points along the length of the paper machine,

  particular to the wet end portion. The applicable

  The constant formation of a depression results in an impulse

  constant negative pressure applied to the wet band, which tends even more to compact the assembly composed of the mud

  and wire cloth. The result is a reduction

  performance that accompanies the progress of the

  ment. Various attempts have already been made to increase the yield of dehydration. For example, an increase in depression has been used,

  the treatment a stronger suction force, either in

  plucking a gradually increasing suction force as compaction increases over the course of the

  dehydration process. We have already imagined a great

  different types of blades, leaflets and deflec-

  ters, with a wide variety of configurations, to strengthen the process of dehydration by depression and negative impulses. For example, it has been imagined to invert traditional blade shapes and to use blades

  staged with different profiles.

  The possibilities of the principle of positive pulsations have been explored to a certain degree, in particular

  which concerns the chainlines. This consists of putting the film

  the wet in contact with sheaves that push the band upwardly and eventually apply it

  a positive impulse. However, this action is impossible

  to be controlled and is limited to a direct relationship between

  the speed and diameter of the rollers. We can not

  in an appropriate manner to ensure an increase in the efficiency of the dehydration process, in particular in combination with scrapers and a depression. It is

  clear that there is room for an improved device for

  chase or dehydration that takes advantage of the advantages of the blade profiles to generate a negative impulse and

  extract the water from the wet sheet and also to apply

  a positive impulse to the band so as to

  the compacted sheet of wire cloth and to

  force the negative pulse dehydration processes yes are produced after the positive impulse. Naturally,

  the device should be adaptable to allow the application

  appropriate negative and positive impulses

  the length of the drying device, in particular

  if it is the wet end of a paper machine.

  Naturally, it is desirable to have a construction

  simple and inexpensive, for example an improved single blade configuration that can be removably mounted in a fixed position in an existing machine

  such as a Fourdrinier type machine.

  In view of the foregoing, the main objects of the invention are to provide a blade adapted to be

  mounted on a drying machine such as a machine

  pier. The blade is designed so that it can exert

  positive impulse on a wet band that passes over an

  wear face of this blade. Moreover, the blade can also

  also include another part which presents a configuration

  ration capable of facilitating the application of a ne-

  gative to the wet band for dehydration.

  An object of the invention is to provide a blade of the above type which is of a unitary construction and adapted to be mounted on a type of conventional machine well known such as a Fourdrinier type machine. the blade is adapted to be mounted in multiple copies to form a row of blades which have aligned wear surfaces on which a wire mesh and a sheet superimposed thereon pass, the assembly forming a wet band. The blade is adapted to be mounted in such a way

  that an appropriate source of depression applies a depressive

  to dehydrate.

  The blade according to the invention is designed with a front edge which has a slope profile, so that it is inclined upwards in the direction of movement towards the sheet, thereby facilitating the backflow of water towards the strip. for the formation of positive pulses. For example, the slope may form an angle of about 100 with the upper wear surface, which is generally in a position at

  roughly horizontal when mounted on the machine.

  The blade according to the invention can also present in the

  region of its rear edge, a configuration designed to

  cilitate the application of a negative impulse in order to

  Tribute to extract the water from the wet band. In one embodiment, this configuration has the shape of a step so as to form a recess in the region adjacent to the trailing edge, so that the water can be drawn through this recess and be sent to a flow slot. approp-riate

  located downstream the blade, considered in the direction of movement

wet tape.

  An object of the invention is therefore to provide a blade with angles oqui tend to print a pulse

  positive and a negative impulse to the canvas and the film.

  forming together a wet band that circulates in the

  China to paper during the training operation. The positive impulse tends to detach first from each other the sheet and the fabric which are more or less entangled with each other.

  in the other, and the sheet is then more easily

  hydrated under the action of the negative impulse. In general,

  the positive impulse applied to the wet band makes it possible

  to dehydrate more effectively under the influence of

  following dehydration The blade is adapted to be mounted on a suction box of a paper machine

  classic Fourdrinier type to extract water from the

  the. It is particularly adaptable to the dewatering devices provided at the wet end of the paper machine, in particular on the assemblies where

depression.

  A bevel configuration adjacent to the front edge of the blade according to the invention facilitates the appearance of water on the underside of the wet band, the water engaging in the slot formed between the band and the sloping surface, so that it rises, enters the band and passes through the band while the band is kept applied

  downwards by the following suction units.

  An object of the invention is to provide a combined blade

  0 with a positive chamfer angle in the ad-

  to the front edge, to produce a positive impulse,

  a step adjacent to the back edge to facilitate

  establishing a negative consecutive pulse when the blade is mounted in a suction device, thereby obtaining a drying or dehydrating apparatus

more efficient.

  One goal is to achieve a blade structure that

  creates positive impulses in certain places which

  take the first blade of a dehydrating element in a Fourdrinier type machine, in combination with wet boxes, with depression leaflets and with

  flat boxes. the principle of the blade according to the invention

  may also be extended in the sense that

  the front edge of any fixed device

  placed under the means of formation of the sheet, by

  example of leaflets and / or baffles.

  In summary, a positive pulse drying blade is provided to facilitate the removal of a liquid from a wet web. The blade comprises means for dismountably mounting on a drying machine. It is provided on the blade an upper wear surface for

  cooperate with the wet band that passes on it.

  The blade has a leading edge whose configuration tends to direct the liquid on the underside of the band towards the band, to apply a positive impulse to the wet band, ie an upward pulse in the band.

  meaning that moves away from the upper wear surface of the la-

  to separate the elements of this band and facilitate

  bed the liquid extraction from this downstream band. The blade

  also includes a portion forming the trailing edge, which -

  is spaced from the next blade to provide a flow opening where liquid extracted from the wet web can flow when the web has passed the wear surface of

the blade.

  The blade may also include a portion adjacent to its trailing edge which has a configuration tending to

  extract the liquid from the tape and apply to it an im-

  negative pulse, to facilitate the extraction of the liquid from

  the tape which has been previously subjected to an impulse

  sitive. Other features and advantages of the invention

  will appear in the following description. the

  attached drawings, given only as an example:

  FIG. 1 is a partial view from above of the end

  dampness of a paper machine, on which are shown

  a series of blades according to the invention; FIG. 2 is a partial sectional view taken along line 2-2 of FIG. 1; FIG. 3 is a side elevational view of a blade according to the invention assumed to be disassembled from the paper machine.

Figs. 1 and 2.

  The upper surface of part of the human end

  The use of a Fourdrinier type paper machine 20 is

  shown in FIG. 1. FIG. 2 is a side elevational view of a portion of the machine 20 which comprises a series of spaced apart and aligned dewatering blades, which are mounted on this machine by removable links, in a conventional manner. One of the blades illustrated, the blade 22, is made according to the invention and is placed between two conventional dehydration blades 24. A slot 26 is provided

  in each interval between two blades to allow

  apply a vacuum to the upper surface of the machine 20. Suitable end caps 28 are provided to seal the ends hermetically, so that the

  slots are in the central part of the machine 20.

  The wet band passes over the central part of the machine.

  This strip is in the form of a sheet of

  re it is dehydrate placed on a moving film.

  The leaf is initially in the form of a mud which becomes denser during its course when subjected to normal gravity and depression forces

  additional amounts applied to it during the

  is lying. A source of classic depression (not shown)

  is applied to the machine in such a way that it occurs

  sucking each slot 26. In this way, water

  is sucked through the slits of a conventional suction box

  of a conventional suction tube or similar structure, while air is sucked through the wet band, entraining the water, the mixture of water and air being

  then separated by well known separation procedures.

  While the wet band passes over the upper surface

  the blades in the direction of the arrow in Fig. 2, it comes into contact with parts of these blades forming

  higher wear surfaces and undergoes the action of the de-

  pressure, the combination of these actions sucking air and water taken from the band through the slots 26 to

collect the water and eliminate it.

  The blades 24 are conventional blades of the sponge type.

  which are part of a horizontal wear surface.

  zontal before 30 which ends with a shoulder 32

  nicking with a hollow surface 34. The vertical space

  between surfaces 30 and 34 forms a region by which

  the a depression can be applied to the wet band by

  communication with the slots 26, which enhances the efficiency

  cited the removal of water from the band that passes over the blade. It is usually said that the action of depression

  in this operation applies to the band a negative impulse

  tive. This action also tends to compress the suspension and compact or transform all of the suspension and the wire mesh into a mass or mattress, which

  makes it more difficult to continue the extraction of water.

  To separate the elements of the wet band, we use

read a blade 22.

  As shown in FIG. 3, the blade 22 comprises a protuberance 36 which protrudes downwards

  under its lower face 38 to lock with sur-

  receiving faces conjugated carried by the machine. We have

  shown in FIG. 2 a suitable locking rod which engages with the blade 22 to urge the blade to lift. This type of structure is common to the blades 24, which also include a protrusion 42 projecting downwards which serves to mount the blade on the machine by engaging with a locking rod 44. In this way,

  the blades 22 and 24 are interchangeable and can be dis-

  poses on the machine in the desired arrangement and in the

  position to maximize the performance of the workplace.

dehydration.

  the blade 22 has a leading edge for initial contact with the moving web. the inferior part 46 of the front edge is bent downwards and in the direction of movement, which facilitates the flow of water

  which is sucked through the adjacent slot 26 under the

  fluence of the force of depression or aspiration. the upper portion 48 of the leading edge is tapered or inclined upwardly in the direction of movement to form a

  slot with the wet band in horizontal motion. The

  taper 48 ends with a horizontal wear surface

  upper 50 which comes into contact with the

  the band. Together the lower surface of the band, the bevelled front edge portion 48 and the wear surface 50 form a slot which captures the water extracted from the band and imparts an upward pulse to the water in the direction of crossing. the strip, to detach the compacted sludge on the wire cloth, so that downstream the water can be extracted more easily and more efficiently from the wet band. This action is called the application of a positive pulse to the band. Then, the band reaches the shoulder 52, which is in communication with the surface in

  recess or recessed 54 which is adjacent to the rear edge 56.

  This hollow surface gives rise to a space through which the depression can be transmitted in the same way as described with respect to the recessed portions of the blades 24. In this way, the strip is then subjected to a negative impulse.

  and the band divided into its elements which has been submitted

  to a positive impulse, is more effectively

  moisturized. The water is then discharged through the next slot 26, the flow being facilitated by the downward and outwardly inclined profile of the back surface 5C. An appropriate notch 60 is provided at the rear surface 58 to facilitate the removal of end caps 62 which

  used to seal the ends of the machine

  paper, to concentrate the suction in the central part

  open tral of the slot 26 on which passes the wet band. The positioning of the blade 22 relative to the blades 24 is left to the choice of the user. This blade 22 may be the first blade, the last blade or a blade

  intermediate. In addition, the ratio of the number of

  my 22 and the number of blades 24 is also the choice of the user, since it depends on the effect of pulses that

wants to get in the device.

  In operation, when the wet band is moving in the direction of the arrow in FIG. 2 on the blades 24 and 22, it comes into contact with the wear surface 30 of the blades

  24 and with the wear surface 50 of the blade 22.

  The slurry 26 is applied through the slit 26 to draw air through the wet web and to direct the mixture of air and water through the slits so that it is collected in a conventional manner. When the wet band approaches the

  wear surface 50 of the blade 22, its lower surface for-

  a gap with the chamfered front 48. The water that is sucked through the wet band and located in the lower part of this band is compressed into

  this slot and is pushed upward, across the ban-

  wet, to detach the compacted sheet. The strip thus detached then passes on the wear surface 50 to be placed above the hollow region 54. The depression applied in the hollow region 54 sucks water from the strip

  wet, and the water is then evacuated through the slot 26 si-

  killed at the rear end of the blade 22, this extraction

  being facilitated by the chamfered profile of the surface 58.

  The dewatering efficiency of the web is enhanced by the application of the positive pulse before the application of the suction to the web, which forms a negative pulse

  serving to dehydrate the band. The band, which is still

  latively detached, can then undergo the action of conventional type of blades such as the blade 24, which prints him only a negative pulse. In the treatment, it is possible to apply a positive impulse by means of a blade 22 at any point of the operation to detach the compacted sludge which forms the sheet placed on the wire mesh.

  It was found that it was effective to give the

  inclined front edge portion 48 a slope forming an angle of

  about 100 with the wear area 50 about horizontal

  the. This gives the slot the desired angle and makes it easier to

  flow of water upward through the band for cons-

  position a positive impulse. the lower part 46 of the

  front edge is inclined downwards and in the direction of

  the strip at an angle of about 300 on the vertical

  hold, so that the water and air that were previously sucked off the band during the dehydration process

  are directed down to be effectively collected.

  the blades 22 and 24 are interchangeable and dismountable,

  so that they can be replaced or interchanged at any time.

  wanted. Moreover, they may be formed of

  conventional plastic material or nylon in a conventional manner.

than well known.

1 1

Claims (7)

Claims 1 - A positive-impulse drying blade for facilitating the extraction of a liquid from a wet band, characterized in that it comprises: means (36) for lifting the blade of removable manner on a drying machine so as to leave a free space (26) adjacent to said blade through which the liquid extracted from the strip can flow; an upper wear surface (50) disposed to contact the wet web that passes over the blade; a leading edge (4-6,48) having a profile which tends to force the liquid towards the band so as to apply to the wet band a positive pulse directed upwards and in the direction which moves away from the surface upper wear (50) of the blade, to facilitate the extraction of the liquid downstream; and a trailing edge (56) which leads to the flow space (26) for removal of the extracted liquid from the wet web when the web has completed its passage over the wear surface of the blade.   2 - blade according to claim 1, characterized   the portion (54) adjacent to the rear edge (56)   a configuration that tends to draw liquid from the web and to apply a negative pulse to this web to facilitate the extraction of the liquid from the web that has been   previously subjected to a positive impulse.   3 - blade according to claim 1, characterized in that it is mounted on the wet end of a machine to   paper to dehydrate the wet band.   4 - Blade according to Claim 3, characterized in   whether the blade is mounted on a drying crate or   is suction of a Fourdrinier type machine to remove water from the wet band, which is composed of a leaf and of a metal cloth.   Blade according to Claim 1, characterized in   what it is adapted to fit into a complex set   taking a series of successive blades in the direction of displacement of the wet band, such that the blade 22) generates at least one positive impulse and that at least   one of the other blades (24) generates at least one ne-   the alternation of impulses applied to the human band.   mide azurast effective drying of this band.   6 - Blade according to Claim 1, characterized in   what the drying machine includes a source of depression   which is connected to the blade (22) and the space (26) adja-   cent - the blade to suck the liquid from the wet band and to dry it.   7 - Blade according to claim 1, characterized in that a portion (48) adjacent the front edge is chamfered so as to extend in a direction inclined upwards, that is to say towards the wet band and in the sense of   circulation of the strip, so as to form on the inside face   the band a crack acting on the liquid of   to push it upwards in the band.   8 - Blade according to Claim 7, characterized in   what the drying machine includes a source of depression   which is communicated with the blade (22) of   the belt is held down by the vacuum transmitted to it when the liquid is forced upwards in the region of the leading edge (46, 48) of the blade and enters the band.   9 - Blade according to claim 7, characterized in that the chamfered portion (48) adjacent to the front edge forms an angle of 10 with the upper wear surface (50) of the blade.   - Blade according to claim 7, characterized in that a second portion (46) adjacent to the front edge is inclined downward in the direction of the passage of the Oven belt facilitate the flow of the liquid which is not repressed danls the slot, the initial region of the slot 'both located between   this second part and the wet band.