US3881225A

US3881225A - Method of felting fibrous elements

Info

Publication number: US3881225A
Application number: US398162A
Authority: US
Inventors: Robert D Lambert
Original assignee: MULTIPLY DEV CORP Ltd
Current assignee: MULTIPLY DEV CORP Ltd
Priority date: 1972-03-09
Filing date: 1973-09-17
Publication date: 1975-05-06
Anticipated expiration: 1992-05-06

Abstract

Improvements are disclosed for securing a greater uniformity of the deposition on a moving surface, of particulate material flowing uniformly to the depositing means in a narrow stream, to form a mat of any desired width on the moving surface, by feeding the stream into the center of the intake of a horizontally revolving distributor whose outlet continuously discharges portions of the material into a circular arrangement of inlets of individual conveyors.

Description

United States Patent 1 1 1111 3,881,225

Lambert May 6, 1975 METHOD OF FELTING FIBROUS 2,770,844 11/1956 Lambert 19/155 ELEMENTS Robert D. Lambert, Fort Wayne, Ind.

Inventor:

Assignee: Multiply Development Corporation Ltd., Vancouver, BC, Canada Filed: Sept. 17, 1973 Appl. No.: 398,162

Related US. Application Data Division of Ser. No. 233,244, March 9, 1972.

US. Cl 19/155; l9/l56.3 D0lg 25/00 Field of Search 19/155l56.4; 156/622, 62.4

References Cited UNITED STATES PATENTS 6/1956 Clark et al. 19/l56.3

Primary ExaminerDorsey Newton [57] ABSTRACT Improvements are disclosed for securing a greater uniformity of the deposition on a moving surface, of particulate material flowing uniformly to the depositing means in a narrow stream, to form a mat of any desired width on the moving surface, by feeding the stream into the center of the intake of a horizontally revolving distributor whose outlet continuously discharges portions of the material into a circular arrangement of inlets of individual conveyors.

6 Claims, 11 Drawing Figures DTENTEUMAY sum 3,881,225

sum 2 0F 6 mum??? smrs 3,881,225

Ff-IENIEDHAY 61975 SHEET FGH METHOD OF FELTING FIBROUS ELEMENTS This is a division, of application Ser. No. 233,244, filed Mar. 9, 1972.

BACKGROUND OF THE INVENTION This invention relates to the manufacture of molded structures, comprising fibrous elements and fibrous particulates of various dimensions, and it relates more particularly to an improvement over the method described in US. Pat. No. 2,770,844 for depositing fibrous elements in a layer or mat of predetermined thickness, whereby the effects of variations of either flow rate or inclination of the feed stream of fibrous elements are materially minimized.

As described in the aforementioned patent, the fibrous elements are fed to the center of a rapidly and uniformly rotating duct 16. If the feed is uniform and constant, equal quantities of fibrous elements are deposited into the ingoing ends of separate downpipes having their outgoing ends disposed across the collecting surface. A series of adjustable splash plates 33 serve to broaden the flow of elements from the downpipe and distribute thtm in adjoining strips to form a flat mat across the surface.

If the stream of elements are fed at a uniform rate to the distributor duct and no fluctuations in guantity, quality or direction occur after the elements flow from the distributor duct, a mat of good uniformity can be obtained. However, unless the elements are free flowing, which is seldom the case with fibrous material and never the case with wood wafers, it is practically impossible to secure a flow of elements to the duct which does not experience nomentary fluctuations in volume, direction or rate. Moreover, if the total flow is desired to be increased or diminished, for purposes of changing the thickness of the deposited mat, the means taken to compensate for the change in angle of approach of the stream and the position of its centroid with respect to the axis of rotation of the entrance to the distributor duch requires some adjustments to be made to the lateral positions of the ends of the downpipes or the attitude of the splash plates. The need for adjustment arises from the fact that when the ingoing stream enters the distributing duct at an angle to its axis of rotation, or if the centroid of the stream falls beyond it, and the tube of the duct is in line with that offset, more elements will flow into it than when the tube is in its opposite position. Thus more fibrous elements will be fed into some of the downpipes and less to the diametrically oppositely situated downpipes. The adjustments necessary to overcome a change either in the average rate of flow or the nature of the material is determined by trial and error for specific conditions. This is time consuming because it requires an analysis of areal weights across the mat of the finished structure. The effect of rapid fluctuations in feed rate cannot be eliminated unless the revolving duct is revolved at an impractical rapid rate. The rate is normally limited to a rate which will enable the elements to flow smoothly through the duct, usually less than 80 rpm. It will also be evident that momentary fluctuations in the feed rate to the revolving duct will cause corresponding variations in the angle of approach of the entering feed stream.

SUMMARY OF THE INVENTION To overcome deficiencies of the type heretofore described continuously to deposit elements to form a mat having a uniform thickness across its width, on a moving collecting surface, irrespective of rapid minor fluctuations in the stream of elements, a number of steps, preferably taken in combination, have been devised. Means are provided positively to cause the stream of elements to fall vertically with a substantially circular and uniform cross section, having an axis which coincides with the vertical axis of the entrance of distributing means rotating about the axis, which means discharge the elements into adjacent inlets of a circular arrangement of downpipes. When the distributing means comprises a smooth duct, it is curved backwards, like the impeller of a centrifugal pump, in order to reduce the friction between the elements and the interior of the duct to enable more rapid rotation without stick-slip movement of the elements. Such higher rotational speeds are effective to spread non-uniformities in the rate of flow of the elements over an increased number of inlets to the downpipes. In the alternative, the distributing means may be in the form of a driven conveyor adapted to transport the elements from said entrance to the inlets of the downpipes. The outlets of the downpipes, the inlets of which are substantially diametrically opposite to each other in the described circular arrangement, are located along the same path traversed by the continuously moving collecting surface thereby to correct diametrical unbalances which might be caused by a temporary vertical deflection of the stream of elements entering the distributing means. Finally, the outlets of the downpipes, the inlets of which are adjacent in the circular arrangement, are spaced one from the other across the moving surface by the outlets of other downpipes. While each of these measures, taken alone, will effect improvements, their combination is preferred to achieve best results.

DESCRIPTION OF THE DRAWINGS For purposes of illustration, but not of limitation, embodiments of the invention are shown in the accompanying drawings, in which FIG. 1 is a fragmentary, diagrammatic, side elevational view taken along the line l1 of FIG. 2 of one form of apparatus embodying the features of this invention, with the discharge ends of the downpipes arranged in two rows across the collecting surface;

FIG. 1a is a schematic side elevational view showing a modification of the apparatus of this invention;

FIG. 2 is a diagrammatic plan view taken along the line 2-2 of FIG. 1;

FIG. 3 is a schematic plan view of an arrangement of 48 downpipes having their discharge ends arranged in four rows across the collecting surface;

FIg. 4 is a schematic plan view, similar to that of FIG. 3, showing the arrangements of 36 downpipes having their discharge ends arranged in four rows across the collecting surface;

FIG. 5 is a schematic plan view showing the arrangement of 12 downpipes with their discharge ends arranged in a single row, illustrating a feature of this invention for feeding the distributor means shown in FIG. la;

FIG. 6 is a side elevational view of a modification in the design of the rotating duct shown in FIG. 1 with the feed means shown in FIG. 7;

FIG. 7 is a plan view taken along the line 7-7 of FIG. 6;

FIG. 8 is a plan view of a further modificaton in the design of a rotating distributing means shown in FIGS. 2 and 7;

FIG. 9 is an elevational view taken along the line 99 of FIG. 8; and

FIG. 10 is a sectional end view of the belts and pulleys taken along the line l0l0 of FIG. 9.

Referring now to FIG. 1 of the drawings, the elements 10, in the form of wood wafers, chips or fibers, are advanced on a continuously moving belt 9 and fed in a continuous stream downwardly towards the center of the inlet of a rotating duct 16. Adjustable guide plates 11, of semi-cylindrical shape, are positioned in the path of the following elements to direct the downcoming stream of elements to fall as nearly as possible vertically into the entrance of duct 16. It is desirable, though not essential to the practice of this invention, to provide additional means to insure that the centroid of the cross section of the feed stream coincides with the axis of the drive motor shaft 22 for the rotating duct. For this purpose, a pair of contiguous wheels 40, having substantially semi-cylinderical, concave peripheries, are mounted directly above the inlet of the distributor duct such that the center of the circle formed by the concave rims lies on the axis of rotation of the duct. A motor (not shown) operates to drive the wheels 40 for rotational movement in opposite directions, for downward movement together at their nip, with the periphery of the wheels being shaped to compress the falling stream into a cylinder without crushing the elements. The diameter of the cylinder as well as the diameter of the curvilinear concave peripheral portions of the wheels are dimensioned to be less than the diameter of the entrance of the distributor duct 16.

For some purposes, the concave wheels may be replaced by a pair of vertically traveling endless chains carrying shoes or other attachments having curvilinear and preferably semi-circular concave faces which, when similarly adjusted, form the falling stream of elements into a cylinder the axis of which corresponds with the axis of rotation of the distributor duct.

Shaft 22 is driven by motor 21 to rotate the distributing duct so that its discharge end 26 delivers the elements successively to the ingoing ends of downpipes 27. The inlets of the downpipes are arranged in side by side relation with each other in the circular path. In FIGS. 1, la and 2, the number of downpipes are restricted for purposes of clarity. The distributing duct 16 may be radial in plan, as shown in FIG. 2 of US. pat. No. 2,770,844, but it is preferred to form the distributing duct with a curvilinear contour similar to that shown in FIGS. 2 or 7, so that in plan it sweeps backwards, resembling the impeller of a centrifugal pump. This minimizes the friction of the falling elements on the inside surface of the rotating duct and permits a higher speed of rotation without the inducement of irregular flow which might otherwise be caused by momentary sticking or slipping of the elements as they travel over the surface. It will be appreciated that it is advantageous, for uniformity of distribution, to rotate the distributing duct as rapidly as practical without causing stick-slipping of the elements or excessive windage.

The elements fed in rapid succession to each downpipe issue as a continuous stream onto the surfaces of adjustable splash plates 33 which operate to flatten and spread the streams of elements as they fall to assume a substantially continuous character, as they are deposited onto a moving collecting surface 32 to form the mat 12. Use can be made of a single splash plate 33, but it is preferred to make use of two or more splash plates arranged at opposite acute angles with the vertical in the path of the elements falling from the outlet of the ducts 27, with the splash plates vertically offset radially one from another with opposite inclinations so that the elements move from one plate to the other during movement to the collecting surface 32.

By way of modification, as shown in FIG. la, the ele ments may be feed or blown from the downpipes into a cylindrical mixing and aggregate-separating chamber 20 located above and extending across the collecting surface and which is provided with inlet 20a at the top and an outlet in the form of a slot 23 in the lower quadrant for deposition onto the collecting surface. A swing hammer or other cylindrical member 25 having a serrated peripheral surface, formed of pivotally supported teeth, is mounted within the chamber for rotatonal movement in a direction opposite the angular flow of elements from the outlet slot 23 so that substantially separated elements will flow from the chamber, while heavy aggregates will continue to circulate within the chamber until separated. The underside of the foraminous collecting surface communicates with a chamber having a fan 27a for the withdrawal of air downwardly through the collecting surface to hold the elements thereon.

In accordance with one feature of this invention, downpipes having diametrically opposite inlets are arranged with their outlets in substantially linear alignment for deposition of the elements to form the mat over the width of the moving surface. For example, as shown in FIG. 2, oppositely located

inlets

1 and 6 discharge over the sections of the moving surface 32 identified by the letter A, 4 and 9 over section B, 2 and 7 over section C, 5 and 10 over section D, and

inlets

3 and 8 over section E. Normally, the discharge of elements from the outlets of the downpipes is not along their center lines, with the result that it is desirable to provide means for adjustment of the lateral position of the outlets and for fixing the outlets in their adjusted positions. Minor changes can be made by adjusting the axial inclination of the splash plates 33.

In the event of momentary hiatus or surge in the supply of elements, as the end of the distributing duct 16 passes over the contiguous inlets of the downpipes 27, it would be undesirable to have momentary change reflected in the thickness of the contiguous strips of the mat. To compensate for such variation, as shown in FIGS. 2-5, the adjacent outlets of downpipes 27 are not located over contiguous strips or sections of the mat but, instead, are arranged in a nonsequential speced pattern across the moving surface 32. They are preferably arranged in a systematic pattern in order to distribute any momentary irregularities in the feed, as broadly as possible. Thus, as shown in FIG. 2, the elements introduced into pipe 1 are delivered to section A; pipe 2 to section C; pipe 3 to section E; pipe 4 to section B; pipe 5 to section D, pipes 1 to 5 discharging in one lateral position across the collecting surface while pipes 6 to 10 deposit the elements in another lateral position spaced longitudinally of the first. Because the inlet to pipe 6 is diametrically opposite to the inlet to pipe 1, it discharges over the same section A, and similarly pipes 7 to 10 discharge over the same strips as their diametrically opposite counterparts, as previously described.

In this manner, any variation occuring in the position or direction of the stream of elements entering the distributing duct 16, such as may result from a change in the flow pattern in the stream of elements which is not fully corrected by the guides, if the rotating duct 16 receives more elements in one position than another, the surplus deposited from the corresponding downpipe will be almost fully compensated by a deficiency coming from the downpipe of the opposite inlet, since both will be discharging over the same section.

FIG. 3 diagrammatically illustrates one possible arrangement of 48 downpipes feeding elements to four lateral stations ocrresponding to twelve imaginary strips A to M of the mat being formed. Each downpipe numbered 1 discharges over strip A and the other numbered downpipes discharge over strips B to M, as illustrated in the diagram, and as shown in the left hand portion of FIG. 3. The right hand portion of FIG. 3 shows an equivalent arrangement.

FIG. 4 illustrates another arrangement embodying the features of this invention, with the outlets of 36 downpipes arranged over four longitudinally spaced positions, with nine outlets laterally arranged in each group. In practice, with 36 downpipes, the six-jump spacing of the downpipes, shown in the bottom two lines of FIG. 4, has been found to be preferable with respect to the arrangement of the downpipes to the four rows.

FIG. 5 diagrammatically illustrates the arrangement of 12 downpipes with their outlets arranged in a single row. This arrangement is satisfactory, especially if the downpipes discharge into means, such as the cylindrical mixer in FIG. 1a, to disperse and distribute the elements, especially when such elements are formed of small fine fibers such as artificial silk.

FIGS. 6 and 7 illustrate the preferred means of feeding the streams of elements to the distributor. Such means exert a positive control on the shape of the cross section of the stream introduced into the duct 16. The guides 11, shown in FIG. I, serve this purpose but, because the reflection of the elements from their surfaces is affected somewhat by the manner in which the elements strike the guides, for example whether the majority of edges or flats of wood wafers contact them as they descend, the position of the stream may fluctuate slightly.

In FIG. 6, the elements are preferably discharged from the conveyor 9 by the revolving picker roll 42 so that elements which otherwise tend to cling together will not be discharged in lumps. The stream of elements falls between two revolving

drums

43 and 44 which may additionally have overlapping flanges and in which the concave faces in the periphery may be other than semi-circular, such as of rectangular, elliptical or other curvilinear shape. The drums gather the falling elements into a corresponding narrow rectangular or oval cross section and deposit them over the rotating cupped wheels 40. In the event that some of the elements splash sideways, they may be constrained to fall within the vertical axis of the two cupped wheels 40 by the aprons 45 and/or by the flanges on the

drums

43 and 44. The wheels 40, which turn in the downward direction at their nip, gather the falling elements into a compact cylindrical stream without crushing and discharge the stream vertically in alignment with the axis of the entrance of the revolving duct 16. The drums and wheels are located to accomplish the above.

The cone 46, carrying the drum 16, is rotated either directly by a gear motor or by an endless chain operatively connected to an external motor 48.

In order to reduce the windage of the rotating drum, it is desirable to enclose the duct between the two

cones

51 and 52, as shown in FIGS. 6 and 7. This construction has the further advantage of balancing the duct and protecting the inlets of the downpipes from external falling objects and it also eliminates the danger of personnel coming into contact with the revolving duct.

It will be obvious that either of the

rolls

43 and 44 may be replaced by a vertically moving endless belt or one of the rolls may be replaced by a stationary apron.

A suitable backward sweep for the spiral duct 16 may be calculated as follows: One determines the approximate speed of the elements sliding down through a straight duct sloped at the selected angle, such as an angle of approximately 45, when dropped into its inlet from a height of several feet. In general, the speed will be limited by friction, which will be approximately constant. With wood wafers, the speed will be about 9 feet per second. The time taken for the wafers to fall, such for example as 3 feet vertically down the duct from its entrance, will be about one-third second. During this period of time, if the duct is revolving, such for example at 2 rpm, a point 3 feet down will have moved onesixth revolution or about 2.2 feet. For good results, the duct should be swept back 2.2 feet at this point. The back sweep for other points in the spiral duct can be calculated in the same manner.

It is contemplated that, for certain purposes, for example to overcome a lack of sufficient head room, the downpipes can be replaced with mechanically operated conveyors, such as belt conveyors, arranged to deliver the elements onto the moving surface in the described manner.

To save further head room or in the event that the elements are damp or somewhat sticky and thus introduce uncertainty in their uniformity of flow down the smooth side of the rotating duct as shown in FIGS. 6 and 7, the duct can be replaced with a driven conveying means such as a screw conveyor or a pair of belts, as shown in FIGS. 8 and 9. In this modification, the stream of falling elements is gathered together into a circular cross sectional shape by the wheels mounted on a stationary framework and which have concave faces. These may replace the

drums

43 and 44 of FIGS. 6 and 7 whereby the elements are gathered into a stream of cylindrical shape, which stream continues through the space between the cupped wheels 40. The wheels can be mounted on a stationary framework or, in the preferred practice, they may be mounted on the rotating framework 53 of FIG. 9, for rotation with the

belts

51 and 52 about axes parallel to the shafts of the belt pulleys. This arrangement insures that the stream of wafers will strike the

belts

51 and 52 at the same place to give the same transport time to the pipe conveyors 27, independent of variations in the wafer stream leaving belt 10. If both are mounted on the stationary framework, they are so positioned that the axis of the falling cylindrical stream of elements coincides with the axis of rotation of the horizontally rotating framework 53 carrying the endless distributing

belts

51 and 52. The belts and their motor drives are mounted on the framework 53 rotated about shaft 22 by motor 48. Belt 52 operates about

pulleys

52a and 52b with the bottom run in parallel relation above the major top run of the belt 510 which operates about

rollers

51a and 51b with the lead ing end of the belt conveyor inclined upwardly to about the level of belt 52, while being spaced longitudinally thereof to provide a feed gap 50 through which the elements fall from the wheels 40.

The lower endless belt 510 receives the cylindrical stream of elements on the upper run and transports the elements radially to the surrounding circle of contiguous inlets of pipe conveyors 27. In order to hold the ele ments while being transported from the center of the rapidly rotating framework 53 to the rim, belt 51c, which is preferably cupped by the concave rollers 54, is biased as by spring means in the upward direction against the lower run of belt 52. The latter is driven at the same linear speed as belt 510. This insures that the elements travel uniformly and smoothly from the central axis of the rotating framework 53 to the rim at any speed of rotation. As a result, the speed of rotation can be increased considerably by comparison with that of the rotating drum shown in FIGS. 6 and 7. For some materials, it may be preferable to replace the belts with a screw conveyor.

The mechanical driven

belts

51c and 52, or other conveyor, have an additional advantage over the rotary duct 16 in that, if wheels 40 rotate with the framework 53, the descending stream of elements from these wheels can deviate from the vertical axis of rotation of the belts 510 or 52, or screw conveyor, and cause a lesser change in the rate of delivery by comparison with the same deviation occurring at the inlet of the revolving duct shown in FIGS. 6 and 7. If the wheels 40 rotate with the

belts

51c and 52, their exact position over the belts becomes relatively unimportant.

The top of the framework 53 may be closed, except for a central opening, and its perimeter provided with a series of vanes 55 whereby the performance will correspond to the rotor of a centrifugal fan, drawing air and any stray elements from its center and delivering the entrained stray elements to the inlets of pipe conveyors 27.

It is important to achieve even a slight gain in the uniformity of the areal weight of a mat of fibrous material especially when the mat is to be subjected to a uniform application of heat and pressure for consolidation into a board. Not only will the quality of the board be improved but its cost can be substantially reduced. For example, if the limits of variation in thickness can be reduced from to 2 percent, a savings of 3 percent of the total quantity of fiber and binder is made possible as well as savings in time and heat required for molding. Still greater savings can be achieved by reason of the more uniform concentration of elements in the mat since any unevenness may necessitate a subsequent and costly sanding operation on the surfaces of the finished board. Uniformity will be enhanced, especially when a revolving distributing duct 16 is employed, by insuring that the stream of elements is fed vertically into the inlet of the duct and that the centroid of the stream coincides with the axis of the rotation of the drum, as heretofore described. Additional uniformity can be achieved by increasing the number of downpipes to as large a number as is practical, limited by the need to keep their diameters sufficiently large to avoid the pipes becoming choked by the elements or by adventitious large splinters and the like. Uniformity is further enhanced by locating a plurality of complete units in series along the moving collecting surface. This serves not only to increase the rate of production, but minimizes the amount of additional auxiliary equipment required, since the uniformity of the whole mat can be controlled by a single belt controlling the entire feed, and then splitting the feed into as many streams as there are units, and feeding one of these subsidiary streams to each unit. When multiple units are employed, the speed of the subsidiary stream should be such that they arrive at and are discharged from their particular distributing unit as a given area of the moving collecting surface moves beneath the unit. With this arrangement, each section of the entire feed stream is deposited over a single area as it passes beneath the successive units so that any variation in the size of the subsidiary streams will have little effect on the final uniformity of deposition.

While the inlets to the distributing conveyors have been illustrated and described as being arranged in a horizontally disposed circle, it will be understood that the inlets may be arranged in two tiers with the described rotating conveyor modified to one that oscillates so that its outlet traverses the contiguous inlets of each tier at a uniform rate and, at the end of each tier, move over to the inlet of the adjacent tier and return.

It will be understood that changes may be made in the details of construction, arrangement and operation without departing from the spirit of the invention, especially as defined in the following claims.

I claim:

1. In the method of spreading a falling stream of particulate or fibrous material into a mat formed on a continuously moving collecting surface, the improvement comprising gathering the stream of particulate material into a compact downardly moving cylinder of material with its axis substantially coincident with that of the ingoing end of a rotating conveyor, rotating the conveyor about a vertical axis corresponding to the axis of the cylinder of material, said ingoing end being adapted to receive the stream of compacted particulate material, the outgoing end of said conveyor being adapted to successively feed increments of fibrous material in a non-cylindrical arrangement into circularly arranged contiguous inlets of distributing conveyors adapted to convey and deposit the material at non-contiguous positions across the collecting surface.

2. In the method of spreading a stream of particulate fibrous material into a wide mat formed upon a moving collecting surface, the improvement comprising gathering the stream into a vertically falling compact cylinder the axis of which coincides with that of the inlet at one end of a conveyor rotating about the same vertical axis and having an outlet spaced radially from the inlet whereby the compacted stream of particulate material passes through the inlet to the rotating conveyor for passage to the outlet, moving the outlet of said conveyor successively and continuously in a circular path for feeding said material to adjacent inlets of distributing conveyors, directing the outlets of the distributing conveyors with diametrically opposite inlets in the circular arrangement to the same longitudinal but nonadjacent crosswise portions of the moving collecting surface, whereby the uniformity of the mat across its width is minimally affected by non-uniform delivery or momentary fluctuations in the stream of material fed to the rotating cylinder.

3. in the method of spreading a stream of particulate fibrous material to form a wide mat upon a moving collecting surface, the improvement comprising gathering the stream as it falls into a compact cylinder, the axis of which coincides with the axis of the inlet of a conveyor rotating about a vertical axis and having an outlet spaced radially from the inlet whereby the compacted stream of particulate material passes through the inlet to the rotating conveyor for displacement to the outlet, moving the outlet of said conveyor continuously about a circular path for feeding the material to adjacent inlets of distributing conveyors, spacing the outlets of said distributing conveyors above and across the portion of said surface upon which the mat is to be formed, systematically interspersing across the surface upon which the mat is to be formed the outlets of those distributing conveyors the inlets of which are adjacent to each other, whereby momentary irregularities in the flow of said stream of material to the rotating conveyor have no effect upon adjoining strips of the mat in the direction parallel to its movement, arranging the outlets of said distributing conveyor in a plurality of rows across the collecting surface with the outlets of diametrically opposed inlets in the circular arrangement of the distributing conveyor being placed over the same lengthwise strip of said surface whereby variations of volume or location of the axis of the falling stream of material to the rotating conveyor has minimum effect.

4. In the method of laying a fibrous mat upon a continuously moving collecting surface by feeding a stream of fibrous material continuously to the ingoing end of a moving conveyor which discharges the elements as increments into adjacent inlets of a series of distributing conveyors, the outlets of which are situated across said collecting surface, the improvement comprising arranging all of said outlets so that they discharge the fibrous increments from adjacent inlets to positions across the collecting surface spaced by the other outlets whereby any non-uniformity in the increments fed to adjacent inlets will be distributed over correspondingly spaced longitudinal portions of the deposited mat.

5. in the method of forming a mat of fibrous elements on a moving conveying surface by feeding a stream of the elements to the ingoing end of a horizontally revolving conveyor and continuously discharging increments of said elements to circularly arranged inlets of a plurality of a distributing conveyors whose outlets are situated across and above the width of the conveying surface upon which the mat is to be formed, the improvement comprising placing the locations of said out lets over any longitudinal portions across the width of the moving surface such that each portion receives increments from those said inlets that are situated diametrically opposite in their circular arrangement and that the outlets over adjoining strips have their respective inlets so spaced around their circular arrangement that other inlets of the distributing conveyors are located between them.

6. In the method of forming a mat of fibrous elements on a moving conveying surface by causing a stream of the elements to fall in a circular cross-sectional pattern and distributing portions of the elements from the circular cross-sectional pattern into inlets of a plurality of distributing conveyors arranged in a circle and having outlets situated in at least two rows above and across the portion of the conveying surface upon which the mat is to be formed, the improvement comprising placing the location of said outlets such that the portions of the conveying surface passing beneath outlets aligned in the direction of movement of the conveyor receive portions of the elements entering their respective inlets that are situated substantially diametrically opposite each other in said circular pattern, whereby any nonuniformity in the distribution of the stream of elements caused by diametrical irregularity of distribution is corrected.

Claims

5. In the method of forming a mat of fibrous elements on a moving conveying surface by feeding a stream of the elements to the ingoing end of a horizontally revolving conveyor and continuously discharging increments of said elements to circularly arranged inlets of a plurality of a distributing conveyors whose outlets are situated across and above the width of the conveying surface upon which the mat is to be formed, the improvement comprising placing the locations of said outlets over any longitudinal portions across the width of the moving surface such that each portion receives increments from those said inlets that are situated diametrically opposite in their circular arrangement and that the outlets over adjoining strips have their respective inlets so spaced around their circular arrangement that other inlets of the distributing conveyors are located beTween them.

6. In the method of forming a mat of fibrous elements on a moving conveying surface by causing a stream of the elements to fall in a circular cross-sectional pattern and distributing portions of the elements from the circular cross-sectional pattern into inlets of a plurality of distributing conveyors arranged in a circle and having outlets situated in at least two rows above and across the portion of the conveying surface upon which the mat is to be formed, the improvement comprising placing the location of said outlets such that the portions of the conveying surface passing beneath outlets aligned in the direction of movement of the conveyor receive portions of the elements entering their respective inlets that are situated substantially diametrically opposite each other in said circular pattern, whereby any non-uniformity in the distribution of the stream of elements caused by diametrical irregularity of distribution is corrected.