JPS598555B2 - Method for arranging and depositing fibers in the production of fiberboard, and equipment used therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing rutted fiberboard, and more particularly to a method for arranging and depositing fiberboard in continuous line molding, which has strong physical properties in one direction.

Particle boards made from wood flakes, chips, etc. are largely limited to use as floor underlayments or furniture cores.

However, wood materials used for construction provide strength suitable for handling loads over long periods of time under conditions of species h, taking into account the inherent orientation of wood in its various tissues.

Sawn lumber for various structural applications takes advantage of the straight nature of wood.

However, sawn wood utilizes only a small portion of the forest resources; the majority remains as residue.

Some of the residue can be converted into pulp and paper or open pore wood panel products.

Wood particles are found randomly in the manufacture of panel products depending on the nature of the method used.

However, the properties of open-pore wood panels can be greatly influenced by aligning long wood particles in a preferred direction.

As the degree of alignment increases, the longest dimension of such wood particles can be better aligned in the direction of the grain so that the panel properties exhibit more of the straight properties of the wood.

Advances have been made in the methods and apparatus used to align certain wood particles.

However, granular feedstocks made from selected cellulose materials by friction in disk refiners using heat or steam at normal or high pressures are difficult to handle and properly align.

Most of the raw material consists of very fine hair-like fibers3.
Approximately 0.4536kg to approximately 1.81 per 0.48ffl
When working with lightweight fiber materials such as 44 kg, it is difficult to obtain the desired level of fiber alignment and uniformity at commercially economical production rates using prior art methods and equipment. It wasn't practical.

The alignment chamber was provided with charged walls and/or partitions disposed in upright and perpendicular relation to the horizontal deposition surface for electrostatic alignment.

However, the charged fibers will stick to these planar electrodes and protrude, forming clumps.

This mass eventually reaches a certain point when it becomes too large and randomly collapses onto the mat surface.

As a result, the appearance and weight distribution of the mat is non-uniform.

The present invention obviates these and other drawbacks and disadvantages of the prior art by providing desired fiber alignment and uniform deposition at industrially economical production rates. For example, an elongated electrically conductive rod is placed in the flow path of a lightweight material and is rotated in a controllable manner in contact with the surface of the mat being formed.

The loosely shaped fibers are drawn towards the rod and the forming mat; fiber alignment and deposition is controlled by a combination of electrical and mechanical forces.

Such fibers, which are electrically attracted to the rod, adhere to the rod in the form of spokes.

Rotation of the rod and movement of the mat forming surface is controlled to brush the fibers onto the existing mat surface.

Centrifugal force generated by contact with the mat surface and rotation of the rods breaks the electrical attachment to the rods and deposits the fibers in a controlled manner to achieve the desired alignment ratio (percentage of the number of fibers pointing in the direction of the web/ % of the number of fibers oriented in the transverse direction of the web).

Furthermore, by controlling the electrical polarity and the placement of the rods, an electric field is established with lines of force extending in the direction of mechanical forming and substantially parallel to the forming surface on which the raw material is deposited.

This electric field creates a torque in the direction of movement of the mat-forming surface on the fibers that approach and fall between the rods which align the axes of the fibers parallel to this surface.

Other advantages and contributions will become apparent from a more detailed description of the invention with reference to the drawings.

In the handling of lightweight raw materials prior to fiber arraying, the raw materials are weighed, dispersed, and separated into b fibers as they approach the array depositor.

In the continuous equipment line for fiberboard manufacturing shown in FIG. 1, a feedstock inlet 10 is provided in vertically spaced relation above a forming conveyor 11 showing a web 12 on which a mat of fibrous material is formed.

From the raw material supply port 10 the raw material descends into a distribution stage 14 for distribution transverse to the direction of movement of the raw material towards the web 12, e.g. The raw material is distributed substantially uniformly over a spacing related to the lateral dimension of the plate.

The laterally distributed raw material is stored in the raw material chamber 16 and advanced towards the web 12 by metering means 18.

The weighed raw material is distributed in the web feeding direction over a preselected length by longitudinal distribution stages 20,
In combination with the lateral dimensions established by this, the area of deposit of the mat-forming fibrous material is determined.

The material, which is substantially uniformly distributed over a preselected deposit area, moves toward the web 12 through the fiber separation stages 22.

The fiber tufts are broken down into individual fibers by passing through a fiber separation stage 22 as the raw material is passed in the direction of the web 12.

The feed, distribution, metering, and fiber separation means are for delivering the feed at a suitable production flow rate over the deposition area while moving the individual fibers toward the mat-forming surface substantially free of air disturbance effects. It is set in.

According to the invention, moving through an open-ended flow chamber 24 for array deposition; the web 12 moves continuously in the machine forming direction as indicated by arrow 26 under the control of guide drive roll means.
The mat formed on the continuous web 12 is then conveyed onto a conveyor 28 for transfer to the press.

Typically, the mat is subjected to heat pressure to polymerize the binder system while simultaneously compressing the mat to a predetermined plate density.

The feedstock passes through the array deposition chamber 24 which is substantially free of air turbulence that would undesirably affect the array.

Electrical energy applied by exciting the rod electrodes in chamber 24 aligns the fibers in the plane of the fiberboard mat with the long axes of the fibers substantially aligned in the forming direction.

The present invention teaches the use of a combination of electrical and mechanical forces to achieve desired alignment and substantially uniform deposition over a predetermined area.

According to FIG. 2, array deposition chamber 24 includes guide walls delimiting an open flow structure through which raw materials are conveyed as indicated by arrows 30.

Guide walls of the flow chamber delimit the deposition area.

With respect to the direction of movement of the web 12 indicated by the arrow 26, the guide wall 32 is located at the tip of the deposition area, and the guide wall 3
4 is located at the rear end of the deposition area.

According to the invention, the desired alignment is carried out uniformly over the entire deposition area.

A number of conductive rods 36-41 are in selected positions and supported in close proximity to the web 12.

The bars 36-41 extend with their long axes disposed parallel to the deposition region in transverse relation to the forming direction.

The electrical polarity of the rods is selected; in a preferred embodiment, rods 36-41 in each case have the next adjacent rod of opposite polarity;
For example, rod 36 is charged with positive polarity and rod 37 is connected with negative polarity.

The charged long rods 36 to 41 are provided on the web 12 at predetermined intervals in the direction of approach of the raw material.

Each rod is arranged so that the surface of the web 12 is spaced apart from the web 12 to take into account that the thickness of the mat increases as the web 12 progresses longitudinally towards the tip of the structure 24.
in contact with the mat-forming surface on 2.

Therefore, the structure 24 is located beyond the deposition area. Bars that are near the ends are spaced more apart on the support surface of the web 12 of the transfer conveyor than bars that are at the rear end of the deposition area.

The contact relationship between the peripheral surface of the rod and the exposed surface of the mat being formed remains substantially the same regardless of the depth of the mat.

The forming conveyor web 12 consists of a continuous perforated belt woven from nylon or the like.

Part of the teachings of the present invention are that the surface of the web 12 and the conductive rod 4
Includes 4 to 49 supports and electrical contacts.

These bars extend with their longitudinal axes extending in transverse relation to the direction of movement of the web 12.

Preferably such rods have a flat surface for supporting the web.

In the arrangement shown, such rods are connected in such a way that each next adjacent rod is in opposite polarity; for example rod 4
4 is positive and bar 45 is negative.

Although the web 12 is essentially non-conductive, the voltage is high enough that a small electrical current is established through the fiber mat and forming belt.

The dielectric properties of the mat vary depending on the moisture content of the fibrous material or additives in the raw material.

The effect of the matte current is to hold the fibrous material in the web and maintain the desired fiber alignment.

Selective control of the instantaneous polarity of the subsurface conductive rods is achieved by selective placement with respect to discrete field generating rods on the web.

Also shown in FIG. 2, a chamber 52 is provided below the web 12.

Delimited by wall structures 54, chamber 52 can extend over the entire area of the deposit.

Any suitably designed fan means can be connected to chamber 52 to help prevent unintentional escape of dust.

A typical negative pressure level would be approximately 6.35 mm of water.

This slight negative pressure can be used to easily reduce ambient dust around the structure without creating air disturbance forces in the flow chamber 24 that would adversely affect the desired alignment of the fibers.

If the negative pressure is increased, the arrangement ratio may become below standard.

FIG. 3 is an enlarged view of a portion of FIG. 2, showing the electric field generated by the charged rods 36-39 spaced apart from each other on the web 12.

By using opposite polarities of adjacent individual bars 36-39, the electric field strength between the bars increases to the algebraic sum of the voltages established on each bar.

The field voltage available for these rods has an effect on selecting the longitudinal spacing, ie the spacing along the direction of mat formation.

The higher the voltage potential, the greater the longitudinal spacing between the rods.

The electric field includes lines of force extending substantially horizontally between the bars.

For example, in a plane passing through the midpoint of rods 36 and 37, the electric field lines extend parallel to the mat forming surface in the forming direction.

Above and below these central plane field lines, the electric field lines are slightly curved between adjacent conductive bars as shown, but the formation has a main component of the field lines parallel to the mat-forming surface. Maintain array in direction.

Electric field mat 1 generated by the rotating rod of the present invention
The effect on individual fibers moving in direction 2 is shown in FIG. 4, which is an enlarged view of a portion of FIG.

A mat forming surface 60 is represented by a mat 62 formed on the web 12;
7 has opposite polarity with rod 36 being positive and rod 37 being negative.

The fibers descend from the top of the flow chamber 24 along a flow path that is substantially perpendicular to the web 12 .

In the region 64 near the effective electric field, the fibers are randomly arranged with the axes of the individual fibers oriented in any direction in three dimensions; that is, the individual fibers have their long axes oriented substantially in the web plane. The mat can be lowered at any angle between perpendicular to the plane of the web and substantially parallel to the plane of the web, as well as at any angle between a 90 DEG alignment with the direction of movement of the mat.

The fibers attached in contact with the electrically charged rods are arranged radially around each rod in a spoke-like manner.

The fiber deposits attached to the rod can extend lengthwise.

Such fiber strands include fibers attached to and extending longitudinally from the first layer of fibers in contact with the rod.

As the rod rotates in the direction shown through the upper cordant and through the cordrant near the web-forming surface, these spoke-like fibrous protrusions are elongated and closely adjacent.

The rotating rod entrains these attached fibers to the final eudrant near the web 12 so that the fibers come into contact with the mat-forming surface 60.

Rotational centrifugal force and continuous rotation of the rods bring the fibers into contact with the mat-forming surface 60 and serve to break the electrical attraction of the spotted fibers to the rods; these fibers are arranged in a preferred direction in the plane of the mat. Deposited.

The direction of rotation of the rod appears to be such that the rod and the fibers attached to it climb up the rod as the mat moves in the direction shown.

The rods are positioned so that the bottom circumferential plane of each rod is in contact with the surface of the mat on which it is being molded; the web 12 is slightly raised as it passes under the rods due to the suction on the activated rods. It will be done.

This contact relationship causes the fibers to be removed from the bar and the first cord lat portion of the bar is free of fibers only after it passes closest to the mat surface.

The number of rotations of the rods is chosen to optimize the alignment and avoid the formation of fiber clumps on the rods.

In addition to the fibers that adhere to these rods, the fibers that fall toward and between the rods cause the fiber axes to be substantially parallel to the plane of the mat being formed, and the long axes of the fibers to the web. 12; such alignment is represented by the fibers in portion 66 of chamber structure 24.

The sub-plane electrical means or rods 44-49 shown in FIG. 2 help maintain another electrical force in the mat being formed by ensuring a small electrical current in the mat.

The means for positioning, rotating and electrically connecting the elongated conductive rod are shown in FIG.

In this embodiment, a support framework 70 extends along the opposite side of the molding chamber 24 in the machine molding direction.

The support framework 70 has mounting and electrical connection bearings, e.g.
．． 75 and 76, 77 at the rear end.

As shown, the spacing between the web 12 and the rod axis increases in the direction of web movement.

Drive means 84 provide a controlled rotation of the rod.

Additional teachings that can be used to increase production rates and enhance fiber alignment while maintaining consistent results include: maximizing electrostatic field strength while avoiding curvature. monitoring the moisture content of the fibers, electrical conductivity, amount of binder resin contained in the raw material, selection of type and condition, limiting the rotational speed and size of the conductive rods that create the electric field, and for forming the mat. Optimizing the effects of electric field strength is accomplished by monitoring the addition of materials that affect the physical properties of the fibers, such as controlling the longitudinal motion of the conveyor support belt.

The present invention has particular application in working with lightweight fibrous materials.

Pressure-refined wood materials, the materials of which are presented below, have posed particular challenges to the prior art in obtaining desired sequences and industrial production rates.

The wood is broken down in a pressurized steam digester at atmospheric pressure into finer fibers than those obtained from grinding mill conditions.

Various refining methods for producing lightweight fiber raw materials are known in the art [e.g., Thomas M. Maloney (Th
omos M. Modern Particleboard and Pyroprocessed Fiberboard (Modern Pa
rticleboard and dry process
ss Fi terboard ) No. 98.99, 2
See page 12].

The majority of high-pressure steam-cooked wood materials are made up of extremely fine hair-like fibers that can be smaller than 25.4 microns in diameter.

These hair-like fibers can vary in length up to 1.9 cTL, but are typically about 0.653 to 1.27 cm long.

The tendency toward clumping exhibited by this material, similar to that observed in cotton fibers, is rooted in the nature of these extremely fine hair-like fibers.

Most of the weight percent of these pressure disc refined feedstocks consists of heavy, long pieces of wood having diameters up to about 50.8 microns.

Some of these exhibit fibrous properties that allow them to be laminated in the longitudinal direction, while others are hard.

The remainder of such raw material consists of dust-like particles.

According to the teachings of the present invention, between 984 and 3,937 volts/
Appropriate alignment conditions are obtained by the electric field strength established by a rotating bar that exhibits a voltage gradient in crn (volts/
The voltage gradient of cIrL is in any case equal to the distance between the electrodes divided by the positive polarity applied to the electrodes plus the negative polarity voltage applied to the adjacent electrodes at that moment.

) The voltage supply can be conventional; both AC and DC can be used, but DC is preferred as it provides better fiber alignment.

The voltage gradient should remain below the point where the bend occurs.

The voltage gradient at which curvature occurs in air is approximately 4.7, depending on the relative humidity.
27 to about 6,921 volts/CrrL.

Also, lightning leakage increases faster at field strengths greater than 3,937 volts/h.

Typical voltage gradient when working with lightweight materials is approximately 3,15
Control of bar spacing along the mechanical forming direction of the charged bars on the web, which is 0 volts/cfrL, relies in part on a high voltage power connection.

The electric field strength can be increased by using two voltage sources of opposite polarity connected to adjacent bars.

4,724 volts/C with a 5,0,000 volt DC power supply and 1.27 crIL spacing between bars in the machine forming direction.
Voltage gradients up to rIL can be achieved.

The voltage output of the power supply is adjustable.

For low voltage output operation, the bar spacing can be reduced to maintain a predetermined voltage gradient.

The coordination ratio progressively increases substantially linearly as the voltage gradient increases according to the teachings of the present invention.

Within the above range of values, a rod diameter of 1.90 crrL gives the best alignment results.

Smaller or larger diameter rods such as about 1.27 cr
It can be used from IL to 2.54crrL.

However, using rods of 3.18 crI'L or larger gives a lower alignment ratio in the case of the above-mentioned lightweight wood materials.

The metallurgical properties of the rod have little effect as long as the rod is a good conductor.

For the above lightweight materials, the rotation of the rod is approximately 100 to 30
0r. p. It is controlled within a range of m.

The improved coordination ratios and productivity of the present invention allow the use of lightweight pressurized feedstocks with a significantly wider range of moisture content than previously considered practical for wall and partition type plate electrodes.

For example, improved coordination ratios are obtained using moisture contents of about 5 to about 15 weight percent.

This significant increase expands the selection latitude used in resin binder systems while maintaining consistency of raw materials and results.

In the case of prior art chamber and partition wall electrodes, the moisture content range of the raw materials that can be used is limited; most alignment effects are obtained when the moisture content falls below an optimum percentage. do not have.

For example, it is generally believed that a moisture content of 15% or higher is more suitable for obtaining alignment.

In the practice of this invention, a moisture content in the range of about 7'/2 to about 10% is preferred, although the desired sequence ratio can be obtained over a wider range of moisture contents.

However, as the moisture content approaches 20%, the adhesive properties of certain resins, the so-called "stick level", interfere with proper mat formation.

The moisture content of the feedstock can be monitored using conventional measuring equipment for better field strength selection.

Moisture content monitors can be placed along the raw material processing line and activated to maintain the moisture content of a particular raw material if it is shown to be too low. I can do it.

In fact, there are many suitable binder systems that do not significantly impair the achievement of proper alignment.

Resin type K includes urea formaldehyde, phenol formaldehyde, incyanate, and tannin formaldehyde.

The resin can be applied in powder or liquid form.

Resin percentages typically range from about 4 to 10% by weight of dry fiber, depending on usage and product.

With some liquid resins, such as urea formaldehyde, sticking occurs resulting in agglomeration or spheroidization of the fibers.

Low tack resins can be selected to avoid problems interfering with proper alignment and uniform deposition.

The effect of the electric field on the raw material can be modified, for example, by limiting the addition of conductivity-enhancing salts to the fiber material to improve the alignment ratio.

If the manufacturing process requires a very low moisture content, it is advantageous to include a salt such as sodium chloride.

However, in most cases, when using the present invention, the moisture content selected for a particular fiberboard manufacturing process will provide the appropriate electrical conductivity for the desired arrangement.

Although many factors go into evaluating the directional properties of a fiberboard, flexural stiffness, also referred to as flexural modulus, provides a convenient measure of achieving an effective fiber alignment ratio.

Methods and mountings for measuring the properties of arrayed particle boards are known in the art;
John W. Talpot presented at the 8th Washington State University Particleboard Symposium in May.
Electrical Arranged Particleboard and Fiberboard (Electricalall) by nWTalbatt
y A lignee Particleboarda
For random arrays, the ratio of particles in the X direction (forming direction) to the number of particles in the Y direction (perpendicularly transverse to the molding direction) is 1:1.

In the case of fiber alignment in the shaping direction, this ratio increases.

An indicator of the degree of alignment achieved by a fiber is the modulus of elasticity in the direction of mechanical forming (Ex) and the modulus of elasticity in the transverse direction (Ey).
).

Using high pressure refined non-fibers, which have been considered the most difficult to work with, the lightweight raw materials mentioned above, FjXZEY ratios of 2:1 or higher are achieved using the present invention.

The present invention is capable of providing desirable array ratios at economically acceptable production rates over an industrially practical forming area using lightweight feedstocks produced by high pressure refining processes.

For example, at a raw material feed rate of 8,154 kg/h flow rate, the electric field fiber arrangement is 4.88 to 244 kg/h to the desired ratio.
Deposition of fibers at 7+''/min over a deposition surface of approximately 6.96 m can be easily achieved using the present invention.

A fiberboard having a density of 96.11 kg/m and a thickness after curing/cm at a feed rate of about 136 kg/min, a deposition rate of about 6.96 m, and a desired orientation at a speed of 15.24 linear m/min. It can be molded with a certain ratio.

If the desired final thickness is 6.35 mm, such a fiberboard can be produced at 7.62 linear m/min.

In fact, the actual deposition rate of dry fibers exceeds these rates because precured deposition of raw materials is usually over press capacity.

Feeding, distributing, aligning and depositing the raw material at maximum speed to handle the fibers more effectively and more evenly distribute them; if the deposition exceeds the capacity of the press, some of the mats are transferred to the curing press. It is scraped off before entering and returned to the feed and dispersion line.

Although specific structures, physical properties, and dimensional values are listed to clarify specific examples, it should be recognized that modifications within the scope of the present invention may be made by those skilled in the art in light of the above disclosure. be.

Reference should therefore be made to the claims appended hereto to determine the scope of the invention.

[Brief explanation of the drawing]

1 is a schematic diagram showing an apparatus for continuous line production of fibreboard according to the invention; FIG. 2 is a schematic diagram of a cross-section along the machine forming direction of the arrangement and deposition apparatus according to the invention; FIG. FIG. 4 is a schematic cross-sectional view along the mechanical forming direction of the electric field, FIG. 4 is a schematic cross-sectional view along the mechanical forming direction showing the effect of the electric field on the fiber material of the present invention, and FIG. 5 is a schematic cross-sectional view of the electric field forming device of the present invention. FIG. 3 is an elevational view showing the arrangement and rotation structure. 10... Raw material supply device, 11... Molding conveyor, 12... Web, 14...
・Dispersion device, 16... Raw material room, 18...
-Measuring device, 20...Longitudinal dispersion device, 22
...Fiber separation device, 24...Sequence deposition chamber, 2 8...Conveyor, 32,34...
... Guide wall, 36-41 ... Conductive rod, 44
~41... Conductive rod, 60... Mat forming surface, 70... Support framework, 74, 75, 7
6,77...bearing, 78,79,80.
81... Axis.

Claims (1)

[Scope of Claims] 1. In a continuous line process for arranging and depositing lightweight raw materials containing fiber materials and curable binders in the manufacture of directional fiberboard, supplying a lightweight material comprising elongated fibers moving along a flow path substantially perpendicular to such surface for material deposition, such web continuously moving to establish a forming direction; guiding a plurality of elongated conductive rods in the direction of such web, with their longitudinal axes in transverse relation to the forming direction, and in predetermined contact with the web in mutually spaced relation along such forming direction; The electric potential is established on the rods, and the fibers are attracted to the rods, and an electric field is established so that the long axis of the elongated fibers is formed and aligned in the direction of formation of the mat plane. by exerting a force on the fibers moving towards the web, which are being arranged in parallel relation to each other, and by controlling and driving the elongated charged rods to rotate them about their respective axes. The fibers attached to the web are deposited by bringing the fibers into contact with the mat-forming surface presented by such a web, thereby aligning and depositing the fibers in a preferred arrangement using electrical and mechanical forces. The above continuous line method is characterized. 2. A device used in the continuous line production of fiberboard from lightweight raw materials containing finely woven long fibers and a hardening binder, which provides fiber alignment and uniform deposition that enhances the directionality of the fiberboard; means for delivering such lightweight material substantially uniformly dispersed in a deposition region establishing a forming conveyor flow path comprising a continuously moving web exhibiting an expansive surface and forcing fibers in loose form substantially free of clumps; Apparatus for establishing an electric field in the flow path of such material to such a deposited surface region, rotating with its long axis in transverse relation to the direction of movement of such deposited surface and in substantially parallel relation to such deposited surface; Such an electric field establishment means comprising a number of elongated conductive rods placed on the deposition surface, adjacent to the mat-forming surface presented by the deposition of fibers onto the deposition surface, and providing a flow path for the raw material on subsequent deposition of such deposition surface. a number of conductive bars spaced apart along the direction of movement across the such an electric field comprising lines of force that align the long axes of such fibers in a substantially parallel relationship with the mat-forming surface in the direction of movement of the deposited surface; means for rotating such electrically conductive rod; means for controlling the electrical potential of such rod; A device as described above, characterized in that it comprises means for establishing the position of the bar in relation to a preselected spacing above the deposition surface.