US2389024A - Means for forming fiber felts - Google Patents

Description

Filed Aug. 10. 1942 I72 zrwefar v F05! Jkfirawrzlee Patented Nov. 13, 1945 MEANS FOR FORMING FIBER FELTS Robert N. Brownlee, Cloquet, Minn., assignor to Wood Conversion Company, Cloquet, Minn., a

corporation of Delaware Application August 10, 1942, Serial No. 454,281

13 Claims.

This invention relates to improvements in fiber depositing apparatus.

In the forming of felts or blankets by releasing fibers, such as vegetable fibers in a settling or feltforming chamber for dispersal in the atmosphere thereof and deposit upon a receiving member, such as a wire screen, portions of the fibers generally contact the walls of the chamber and cling thereto. Such stray or fugitive fibers accumulate during the operation of the felt-forming apparatus until festoon-like formations occur, and as growth continues they drop from the walls in clusters, fiocs or the like. The dropping of fiber festoons upon the felt being formed impairs the uniformity in density of the felt as well as the felting of the fibers into a well integrated felt structure of the desired strength and resiliency and smooth upper surface. 7

In felt-forming apparatus having a fiber-depositing or settling chamber but little wider than the forming screen, the deposited fiber mass generally is thicker along the margins of the screen by reason of the dropping of fiber clusters or festoons from the side walls of the chamber and by reason of the bafiling effect of the side walls, which induce a relatively high concentration of fibers adjacent such walls and the excessive deposition of fibers along the margins of the screen. The result of such arrangement is that the formed felt or blanket is built up to a greater depth or thickness along the margins thereof, impairing the uniformity in density of the felt and contributing to the formation of irregular margins. Trimming-several inches from the edges of the felt has frequently been necessary heretofore, resulting in waste of formed mat and ineflicient use of the width of the receiving member.

One object of the invention is to provide a feltforming apparatus which prevents festooning, or the accumulation of fugitive or stray fibers upon the walls of the forming chamber from which the fibers can fall in clusters of fiocs upon the felt being formed.

Another object of the invention is to provide means operable within the fiber depositing chamber for collecting fugitive fibers and removing the same therefrom whereby only the regularly deposited fibers enter into the formation of the felt being formed.

An additional object of the invention is to provide fiber depositing apparatus arranged to prevent the deposit upon the margins of the screen of relatively high concentrations of fibers, thereby avoiding the formation of relatively high densities and irregularities in the margins of the felt.

Other objects relate to various features of construction and arrangement of parts which will be apparent from a consideration of the accompanying drawing which illustrates diagrammatically an embodiment of the present improvements.

Fig. 1 is a longitudinal vertical sectional view of a felt forming chamber embodying improvements which are illustrative of the invention.

Fig. 2 is a vertical sectionalview taken on line 2-2 of Fig. 1.

Fig. 3 is an enlarged broken horizontal sectional view taken on line 3-3 of Fig. 1.

In the drawing the fiber-settling chamber is indicated generally by the numeral l0 and comprises front and rear end walls II and II, a top wall l3 and side walls It. An endless fiber-receiving screen of conventional form is indicated generally by numeral IS, the upper run of which extends through the end walls H and I2 of the chamber for receipt of fibers to form mat It. The screen passes around end rollers, as usual, the upper run also being supported conventionally in the desired plane by intermediate rollers I1. The upper run of the screen, as viewed in Fig. l, is designed to move to the right and after leaving the forming chamber the felt on the screen may be conveyed by the screen to other apparatus for additional treatment prior to its removal from the screen. For example, in the forming of deposited-fiber felts involving the use of liquid or other bonding material, the felts are passed through a drying or bond-activating chamber, such as is indicated diagrammatically at I 8, for example, and which per se forms no part of the present invention. 1

In Fig. 1 of the drawing means are shown for injecting fibers into the chamber I0, such means, in the form illustrated, comprising a nozzle l9 through which the fibers are delivered at a substantial velocity by air. The fibers employed may be of any feltable character, but for the purpose of the present disclosure they may be assumed to be vegetable fibers which have been reduced by known mechanism and treatments to, or substantially to, their ultimate form. Such ultimate fibers are light in weight and festoon readily in the walls of the forming chamber. They cling together and grow, much in the manner that snow flakes produce overhanging and festoon-like formations.

The nozzle I 9, or several of the same when desired, may be positioned near the upper portion of the front wall ll of the chamber In and, if desired, disposed at an angle to direct the fibers downwardly and forwardly of the chamber toward the screen [5. The fibers may be discharged by the nozzle or nozzles in a condition of high concentration and be further dispersed within the chamber to provide relatively uniform deposition of the fibers upon the screenas the latter moves within the chamber.

A nozzle 20 is shownin Fig. 1 through which fiber bonding material may be sprayed into the fiber stream within the chamber in instances where a bonded felt or mat is to be produced. Where the bonding material is liquid'adhesive, it greatly augments the tendency of the fibers to festoon and of the festoons to drop without breaking up. It is desirable that the fibers which are blown into the chamber 10 through the nozzle or nozzles I!) be uniformly dispersed in their movement toward. the screen 16 and be deposited thereon to provide a fiber mass which is substantially uniform transversely of the screen. Where the side walls of the forming chamber are relatively close to the margins of the screen, a uniform dispersal of the fibers above the screen frequently is not attained due to the baffling effects or eddy currentsinduced by the side walls of the chamber. Hence along its edges of the screen a higher concentration of fibers occurs which build up the felt at the edges beyond the thickness of intermediate portions. Such felts, when compressed and dried are of greater density along the edges than in the intermediate portions, which condition it is desirable to avoid.

In the present embodiment of the invention the chamber I is substantially wider than the screen as illustrated in Fig. 2. In that figure the side walls It are shown spaced substantially from the edges of the upperrun l of the screen whereby the fibers that drift along the side walls or which cling thereto and subsequently drop therefrom in flocs or clusters do not alight upon theforming blanket or felt. In the chamber construction illustrated in the drawing a gutter 2| is shown at the bottom of each of the side walls ll. The bottoms of the gutters are below the level of the upper run of the screen l5, into which gutters the fiber festoons that fall from the side walls, and also the excessively high concentrations of fibers which occur along the walls, are deposited. An endless belt or conveyer 22 is shown for each gutter for conveying the fibers therefrom. The conveyers 22 pass over end rolls 23, 24, adjacent the latter of which are provided rotary brushes 25 for removing the fibers from the conveyer for collection in a trough or troughs 26 from which the fibers may be returned to the shredder for re-delivery to the nozzle l9.

The above described structure avoids the excessive build-up of fiber thickness along the margins of the felt on the forming screen and contributes to the desired uniformity in density of the felt and the smooth top surface given to it by passing it under a compression roll 2'I- to reduce the fiber mass to the desired thickness and to efiect intimate inter-felting of the fibers. By avoiding excessive deposition of fibers 'on the margins of the screen and on thefioor contiguous the margins, a relatively straight line definition is given to the edges of the felt and hence less material, if any, need be trimmed from the edges than has heretofore generally been required.

The fine, light weight ultimate fibers not only tend to festoon on the side walls 14 ofthc chamher but on the rear wall [2 and the top wall 13 as well, in instances where the intake nozzle 19 is arranged to direct the fibers toward the rear of. the chamber. For the purpose of avoiding the festooning of the fibers on these walls and the dropping of the same in clusters and clumps upon the sheet being formed, means preferably are provided for effecting either a continuous or intermittent removal of the fibers which tend to cling to'such walls.

The fiber-removing means mentioned are illustrated as conveyers or belts, substantially co-extensive in width with the respective walls and arranged tocarry the clinging fugitive fibers from the chamber. Thus, at the rear end of the chamber an endless belt-like conveyer 28 is shown with a vertical inner run 28 inside the chamber. The fugitive fibers which cling to the conveyer 28 are removed from the chamber either by continuous or intermittent operation of the conveyer. A rotary brush 30 brushes the fibers from the conveyer into a trough or collecting receptacle 3| from which they may be returned to the shredder.

Where the top of the chamber is so close to the turbulent zone in which the fibers are dispersed upon introduction, fibers tend to festoon on the top wall.

A similarfugitive fiber conducting conveyer 32 may be provided at the top of the chamber with a lower run 33 beneath the wall l3 and an upper run 33' above the wall 13. Fibers that stick and cling to the run 33 are carried to the exterior of the chamber and are removed from the conveyer by suitable means such as a rotary brush 34 which deposits the fibers in a receptacle 3! from which they may be returned to the shredder. Inasmuch as the general direction of the fiber movement within the chamber I0 is to the right, an excessive accumulation of fibers generally does not occur on the front wall ll. However to avoid the dropping of any such festoons as may form on the wall II or such as may more readily form on said wall should the position of the nozzle or nozzles l9 be substantially altered, a horizontal conveyer 36 is shown for catching such fiber clusters and preventing deposition thereof on the screen. The conveyer 36 is shown with the upper run supported by a plate 3'! with the edge of the conveyer extending at least to the edge of the plate. The fibers which settle upon the conveyer are removed to the exterior of the chamber where they are removedfrom the conveyer, as by a brush 38 and deposited in a receptacle 3!. A horizontal conveyer'structure such as is used 2 on the wall ll may likewise be employed on the wall 12 if desired in lieu of the vertical conveyer 28, or vertical conveyers may be employed on the side walls I in instances where the screen is substantially the full width of the chamber, in lieu of the stray fiber collecting means shown. Be

neaththe upper run of the receiving screen a suction box 40 is shown, sufficient suction from any suitable source being maintained in the outlet duct ll thereof to augment the uniformity of the downward flow of air through the screen and uniform deposition of the fibers thereon. The suction box serves in part at least to remove air introduced with the fibers. The suction box may be operated to remove all air and to draw air in through openings into the chamber.

As the fibers accumulate on the moving screen to form a mass of the desired thickness, the mass passes from the chamber 10 beneath the compression roll 21 which effects further inter-felting of the fibers and reduces the fiber mass to a well integrated felt of the desired thickness. Upon emergence from the drier la the felt is removed from the screen. By reason of the procession of means for removing the stray or fugitive fibers from the settling chamber, the uncontrolled and non-uniform deposit of fibers on the screen is avoided and a felt of greater uniformity in density and interfelted characteristics is provided.

By means of the apparatus disclosed only the regularly deposited fibers, that is, those which travel freely and directly, or indirectly, from the nozzle I! to the screen, and which therefore are relatively well dispersed and are laid down uniformly, become constituents of the felt, while theirregularly deposited or fugitive or stray fibers which settle or tend to settle on or along the walls are removed from the chamber.

The apparatus shown and described is to be considered merely as illustrative of the invention asit is apparent that various modifications of the apparatus may be resorted to without departing from the spirit of the invention.

I claim:

1. Fiber-depositing apparatus comprising a fiber-settling chamber, a fiber-receiving member therein for receiving regularly deposited fibers, means for releasing fibers within the chamber at an elevation above said member, and endless conveyer means having a run operable within the chamber and of a length to traverse a wall thereof adjacent an edge of the receiving member for receiving deposited fugitive fibers and removing the same from the chamber.

2. Fiber-depositing apparatus comprising a fiber-settling chamber, a fiber-receiving member in the chamber, means for releasing fibers-within the chamber for deposition upon said member, and conveyer means operable within the chamber for preventing the deposition on said member of fiocs of fibers that initially deposit on the walls of the chamber.

3. Fiber-depositing apparatus comprising a fiber-settling chamber, means for projecting fiber into said chamber for deposition therein, a traveling fiber-receiving conveyer within said chamber of less width than said chamber, and means within the chamber co-extensive with and adjacent the margins of said fiber-receiving conveyer within the chamber and at an elevation difierent from the elevation of said conveyer for receiving fugitive fibers that'are deposited adjacent and beyond the margins of said fiber-receiving conveyer and removing the same from the chamber.

4. Fiber-depositing apparatus comprising a fiber-settling chamber, means for projecting fibers into the chamber, a fiber-receiving member within the chamber, and a plurality of means each adjacent and operable along a wall of the chamber and of a length to traverse the full extent of the chamber in the direction of movement of the respective means for removing from the chamber fugitive fibers that are deposited on said means respectively.

5. Fiberdepositing apparatus comprising a fiber-settling chamber, a fiber-receiving member therein, means for injecting fibers into the chamber above said member to efiect dispersal of the fibers within the chamber for deposit upon said member, and conveyers within the chambers having portions adjacent and traversing various walls thereof and of such length as to traverse the extent of the respective walls in the direction of movement of the conveyers for receiving fibers that initially tend to settle on and cling to the respective walls and for removing the same from the chamber.

6. Fiber-depositing apparatus comprising a fiber-settling chamber, a fiber-receiving member adjacent the bottom of the chamber, means for releasing fibers into an upper portion of the chamber for dispersal therein and for deposition upon said member, and fiber-removing means within the chamber operable in a direction and of a length to traverse the full extent of a wall of the chamber in the direction of operation of said fiber-removing means for receiving and removing from the chamber the fugitive fibers that are deposited and otherwise collect upon said fiberremoving means.

'7. Fiber-depositing apparatus comprising a fiber-settling chamber having side walls, a fiberreceiving member in the lower portion thereof and of a width less than the width of the chamber and spaced at its edges from the side walls of the chamber, means for releasing fibers into an upper portion of the chamber for dispersal therein and for deposition upon said member, and

means along the edges of said member for removing from the chamber the fibers that settle in positions laterally outside of said fiber-receiving member.

8. Fiber-depositing apparatus comprising a fiber-settling chamber, a fiber-receiving member therein, means for releasing fibers within the chamber at an elevation above said member for deposition upon the latter, and endless conveyers each having a run within the chamber of a length for fully traversing a wall of the chamber in the direction of operation of the respective conveyers and movable to the exterior of the chamber for.

receiving irregularly deposited fibers and removing the same from the chamber.

9. Fiber-depositing apparatus comprising a fiber-settling chamber, a fiber-receiving member in the lower portion thereof, means for releasing fibers within the chamber at an elevation above said forming member for deposition thereon, and troughs in said chamber adjacent the edges of said member for receiving fibers that settle into the lower portions of the chamber but laterally of said member. Y

10. Fiber-depositing apparatus comprising a fiber-settling chamber, a fiber-receiving member therein, means for releasing fibers at an elevation above said member for deposition thereon, and means for preventing the deposit on said receiving-member of wall-formed fiber-fiocs comprising a plurality of conveyers operable within the chambers along the respective walls thereof for receiving wall-formed fiocs and irregularly deposited fugitive fibers and removing the same from the chamber.

11. In a fiber-settling chamber, a fiber-receiving member for receiving regularly deposited fibers, means for introducing fibers into the chamber above said member, and an endless conveyer having a run movable within the interior of the chamber contiguous to a wall thereof and of a length to traverse the wall from edge to edge in the direction of movement of said run for receiving and removing from the chamber fibers that tend to settle on said wall.

12. In a fiber-depositing chamber, twoparallel side walls, a fiber-receiving member disposed between said side walls on which to build a fiber mat by deposition of fibers, there being an intervening space between each edge of the member and the corresponding side wall, whereby fibers deposited in the chamber fall both on said member and into said spaces, and means for collecting the fibers or masses thereof which fall into said spaces from the chamber or from the edges of said member.

13. In a. fiber-depositing chamber, two parallel 5 side walls, a fiber-receiving member movable between said side walls parallel thereto on which to build a fiber mat by deposition of fibers, there

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