US2840865A - Method and apparatus for depositing fibrous elements in the manufacture of fibrous structures - Google Patents

Description

2,840,865 EMENTS July 1, 1958 R. H. REED METHOD AND APPARATUS FOR DEPOSITING FIBROUS EL IN THE MANUFACTURE OF FIBROUS STRUCTURES Filed Oct. 22. 1954 INVENTOR. RUSSELL REED A Tl'ORNEVS United States Patent METHOD AND APPARATUS FOR DEPOSITING FIBROUS ELEMENTS IN THE MANUFACTURE OF FIBROUS STRUCTURES Russell H. Reed, Sandpoint, Idaho, assignor to Changew0 od Corporation, Chicago, 111., a corporation of Illi- 11015 Application October 22, 1954, Serial No. 464,039 12 Claims. (Cl. 19155) This invention relates to the manufacture of consolidated structures of fibrous elements such as wafers, chips, slivers and the like, and it relates more particularly to the deposition of fibrous elements to form endless mats which may be divided into sections for consolidation under heat and pressure into hard board panels and the like. As used herein, the term fibrous elements is meant to include fibers, wafers and chips produced of woody material and the like. These elements may be present in various shapes such as discs, ovoids, squares, rectangular members, fibrous and other simple shapes and they may be present in various dimensions ranging from individual fibers on up to Wafers of substantial dimension, but it is preferred to make use of fibrous elements having less than inches in any length or width to enable use in automatic systems for depositing the fibrous elements as employed in the practice of this invention. The term may include fibrous elements which are severed from wood by cutting parallel to and along the grain and the invention has particular application to the processing of thin fiat wafers of the type described in copending applications Ser. Nos. 344,088, now abandoned, 344,089 and 375,152, and now'U. S. Patents Nos. 2,773,789 and 2,776,685 respectively, in which wafers of less than 5 inches in length and varying in thickness from 0.002 to 0.065 inch are cut parallel to and across the grain of the wood.

In the manufacture of boards and similar molded structures by a process in which the fibrous elements are felted, either wet or dry, to form a mat, the fibrous elements are usually coated with a suitable binder, preferably in dry powder or particulate form. The fibrous elements are deposited automatically by gravitational means onto a collecting surface moving endlessly in one direction to form a continuous mat, for example as upon caul plates aligned in end to end relation for movement as an endless belt through the fiber depositing zone. In general, the fibrous elements are supplied for issuance in a uniform concentration from orifices situated uniformly across the collecting surface, such as for example by the means described in copending applications Ser. No. 381,448, filed September 21, 1953, and entitled Method and Apparatus for Deposition of Fibrous Elements in the Manufacture of Fibrous Structures, and Ser. No. 371,055, filed July 29, 1953, now U. S. Patent No. 2,770,844 and entitled Method and Means for Felting Fibrous Elements. The thickness of the mat of the fibrous elements which is formed upon the surfaces of the caul plates may be varied depending upon the feed rate of the fibrous elements and the linear speed of the collecting surface during passage through the fiber depositing zone.

In the manufacture of laminar structures wherein the character of the fibrous elements may be varied from the outer lamina to the inner cores, manufacture by processes heretofore described can conveniently and efficiently be carried out with a number of such fiber depositing systems arranged in sequence to deposit successive layers of the ICC fibrous elements one upon the other to produce the mat for consolidation by molding under heat and pressure. The first and last fiber depositing heads will provide the top and bottom lamina of the structure formed. Unless the structure is to be formed with a face veneer or with a veneer or cover sheet laminated thereto, it is desirable to control the fibrous elements deposited in forming the outer lamina to avoid large variations in the types, in the kind, and in the dimensions of the fibrous elements deposited. In general, it is most desirable, especially from the standpoint of appearance, to form the surface lamina .of fibrous elements of large thin wafers having substantially uniform dimension.

When the material forming the surfaces of the composite structures constitutes fibrous elements which are widely varying in dimension, such as in their lengths and widths, many difficulties arise in the steps of processing and such variation in particle size detracts materially from the appearance of the structure. The desire for uniformity in the dimension of the fibrous elements coupled with the desire to make use of thin wafers of substantial dimension has been in conflict with the continuous processes for mass production heretofore employed for handling the fibrous elements in deposition to form mats. Such large thin fibrous wafers are readily split lengthwise along the grain into separate entities of smaller dimension during handling in such continuous operations. Screening to separate the wafers for size during an intermediate stage of the process has been found to be impractical because fractures continue to occur in screening and in the subsequent handling of the fibrous elements. In addition, the separation of the fine or smaller elements from the remainder presents a problem because disposal of the elements would be uneconomical and use therefor requires an increase in the number of fiber depositing heads and in the space required therefor.

In the attempt to minimize breakage or splitting of the fibrous elements, use has been made of fibrous elements cut to thicknesses greater than desired for use in producing smooth flat surfaces on the molded structure.

Even then, breakage and splitting occurs so that it has been impractical from a commercial standpoint to deposit fibrous elements to form surface lamina which are substantially free of separated narrow splittings or small particles torn or rubbed from the fibrous elements. Such smaller particles formed of wafers of greater thickness provide surfacerblemishes especially on the surfaces of the product which are adjacent to the caul plates in molding.

It is an object of this invention to provide a method for handling fibrous elements to effect an efficient separation for size during travel of the fibrous elements immediately in advance of deposition onto the collecting surface to form the mat thereby to eliminate the possibilities of further splittings subsequent to separation.

Another object is to provide apparatus and a method for receiving the fibrous elements in uniform distribution across the width of the surface for forming the mat and for laying the larger or intact fibrous elements in one position and the smaller or separated fibrous elements in another position longitudinally along the collecting surface during its travel thereby to form separated lamina of the large and small elements from the fiber stream.

More specifically, another object is to provide a method for separating a stream of discrete fibrous elements of mixed dimensions into two or more streams containing the elements according to their size and to deposit them in separate lamina to form a mat without recourse to the use of additional fiber depositing heads or apparatus.

A still further object is to produce apparatus and to provide a method for depositing fibrous elements in a continuous, mass production operation to form mats in which the fibrous elements constituting the portion of nally forming a part of the same fibrous stream. As illustrated in Figures 4 and 5, one or more additional fiber depositing heads 11 may be subsequently employed to form additional layers of fibrous elements on the previously deposited lamina. Since the fibrous elements forming the intermediate layer or core of the mat are concealed from the surface, separation for dimension is unimportant and such core sections may be formed of rough cut fibers of greater dimension or greater variable in dimension or of different materials such as low cost fibrous elements or elements adapted to introduce specific propertiessuch as lower gravity, softness, insulation charac teristics or the like.

'In a multiple system of the type described, the top surface of the mat may be formed to embody characteristics similar to that of the bottom by the use of a rake 18 positioned in the path of the stream issuing-from the last of the fiber depositing heads 11 with the prongs of the rake positioned at a forward incline to permit the smaller of the fibrous elements to fall through between the prongs for deposition onto the previously deposited layers while the larger or intact fibrous elements are displaced forwardly over the prongs for deposition to produce the up per surface lamina of the mat.

In Figure 5, illustration is made of a similar system wherein the outer laminae of the mat are adapted to constitute the fibrous elements of smaller dimension with the larger intact fibrous elements in the adjacent areas in the interior thereof. For this purpose, the rake 18 below the first orifice 11 is positioned with the prongs extending in the direction of movement of the collecting surface or caul plates while the rake 18 lying in'the path of the stream of fibrous elements issuing from the last orifice 11 is positioned with the prongs extending in the reverse direction which is opposite to the direction of movement of the caul plates. Fibrous elements issuing from the orifices 11 in between may be allowed to fall gravitationally for deposition in uniform distribution to form the core of the mat.

By way of modification, the desired separation for deposition of the intact fibrous elements to form laminae substantially independent of the smaller and broken fibrous elements issuing from the same stream may be achieved also by the use of a foraminous drum 30 positioned between the caul plates 15 and the stream of fibrous elements 11 issuing from orifices in uniform distribution for deposition onto the caul plates. The drum 30 is perforated in its peripheral surface which enables the smaller fibrous elements to fall through the drum onto the caul plates 15 by gravitational force. The larger or intact wafers will be separated out onto the periphery of the drum which carries the fibrous elements forwardly or rearwardly for deposition onto the caul plates in advance of or behind the smaller elements, depending upon the direction of rotation of the drum. When, as illustrated in Figure 6, the drum is rotated slowly in a clockwise direction over a collecting surface traveling continuously in the direction to the left, the larger or intact fibrous elements will be displaced by the drum for deposition onto the collecting surface in advance of the smaller fibrous elements, which fall through the drum, so that the larger or intact fibrous elements will be contained in the surface laminae adjacent the caul plates. If, on the other hand, the drum 30 is rotated in the opposite direction, the smaller fibrous elements falling through the drum will deposit first upon the caul plates in advance of the larger or intact elements displaced from the stream in the direction of movement of the collecting surface.

In Figure 6, illustration is made of the use of a separating drum 30 in communication with a series of orifices 33 at the end of down pipes 34 employed in a fiber depositing system described in copending application Ser. No. 371,055 and now US. Patent No. 2,770,844. The plates 35 represent splash plates in communication with the outlet ends of the orifices'and which function to 6 spread each individual stream of fibrous elements later ally upon emission and thereby to achieve uniform distribution of fibrous elements for deposition on the collecting surface, eliminating grooves or zones of depletion.

It will be understood that the drum system may be used with equal eifectiveness in the streams of fibrous elements formed by the apparatus illustrated in Figures 1 to 5 or with any other fibrous stream capable of being intercepted by the drum and that the rakes may similarly be interchanged for the drum in the fiber depositing system shown in Figure 6 or for use with other streams of fibrous elements.

It will be apparent from the foregoing that I have provided a simple and expedient means for processing fibrous elements in a stream for separation of the elements to displace the larger or intact members from the broken down or smaller members for deposition onto a collecting surface and that such means for separation may be achieved without interference with the flow or distribution of the fibers and at a stage in the operation which minimizes the possibility of subsequent breakdown of fibrous elements and without causing excessive breakage thereby to enable the formation of laminae of selected materials. It will be evident further that the concepts embodying features of this invention may be adapted for the continuous operation in mass production of mats of fibrous elements, with or without binder previously applied to the surfaces thereof, for use in the manufacture of consolidated structures in the form of boards and panels and in which the surface lamina of the consolidated members may be selectively formed of thin wafers of substantial dimension to improve the appearance thereof.

It will be understood that various changes may be made in the construction, arrangement and operationwithout departing from the spirit of 'the invention, especially as defined in the following claims.

I claim:

1. Apparatus for the deposition of fibrous elements varying in dimension to form a mat in which the fibrous elements of larger dimension are deposited in a layer substantially separated from the layer of fibrous ele ments of smaller dimension, comprising a collecting surface moving endlessly in a longitudinal direction, means for issuing the fibrous elements in an endless stream in uniform distribution crosswise from an outlet in spaced relation over the collecting surface, and a member extending crosswise of the collecting surface and intercepting the stream of fibrous elementshaving foramens dimensioned to permit passage therethrough of fibrous elements of smaller dimension for deposition onto the collecting surface while the fibrous elements of larger dimension are displaced longitudinally by the foraminous member for deposition onto the collecting surface longitudinally of the fibrous elements of smaller dimension.

2. Apparatus for the deposition of fibrous elements varying in dimension to form a mat in which the fibrous elements of larger dimension are deposited in a layer substantially separated from the layer of fibrous elements of smaller dimension, comprising a collecting surf-ace moving continuously in a longitudinal direction, means for issuing the fibrous elements in an endless stream in uniform distribution crosswise from an outlet spaced over the collecting surface, and a member extending crosswise of the collecting surface and longitudinally at a downward incline across the path of the stream of fibrous elements having foramens dimensioned to permit passage therethrough of fibrous elements of smaller dimension for deposition onto the collecting surface while fibrous elements of larger dimension are displaced from the stream of fibrous elements over the surface thereof for deposition longitudinally of the fibrous elements of smaller dimension onto the collecting surface.

3. Apparatus for the deposition of fibrous elements in forming a mat as claimed in claim 2 in which the foraminous member is inclined in the direction opposite the direction of movement of the collecting surface for deposition of the fibrous elements of larger dimension onto the collecting surface to form a layer in advance of the deposition of fibrous elements of smaller dimension passing through the foraminous member.

4. Apparatus for the deposition of fibrous elements in forming a mat as claimed in claim 2 in which the foraminous member is inclined in the direction of movement of the collecting surface for deposition of the fibrous elements of larger dimension to form a layer over the layer of fibrous elements of smaller dimension passing through the foraminous member for deposition in advance on the collecting surface.

5. Apparatus for the deposition of fibrous elements in forming a mat as claimed in claim 2 in which the foraminous member comprises a plurality of interconnected elongate rods extending in closely spaced apart parallel relation through the stream of fibrous elements issuing from the outlet.

6jApparatus for the deposition of fibrouselements varying in dimension to form a mat in which the fibrous elements of larger dimension are in a layer substantially separated from the layer of fibrous elements of smaller dimension, comprising a collecting surface moving continuously in a longitudinal direction, means forissuing the fibrous elementsin an endless stream in uniform distribution crosswise of the collecting surface andfrom an outlet spaced upwardly therefrom, and a foraminous drum rotatably mounted for movement through the path of the stream of fibrous elements about an axis crosswise of the collecting surface having fora'mens dimensioned to permit passage of fibrous elements, of-sinaller dimension therethrough for deposition onto the collecting surface while fibrous elements of larger dimension are retained on the surface of the drum for displacement longitudinally from the stream for deposition onto, the collecting surface.

7. Apparatus for the deposition of fibrous elements in forming a mat as claimed in claim 6 in which, the foraminous drum is rotated in a direction whereby the peripheral portion engaged by the stream moves in a direction opposite the direction of movement of the collecting surface to displace the fibrous elements of larger dimension rearwardly to form a layer in advance of the deposition of fibrous elements of smaller dimension passing through the foraminous drum.

8. Apparatus for the deposition of fibrous elements in forming a mat as claimed in claim 6 in which the foraminous drum is rotated in a direction whereby the peripheral portion engaged by the oncoming stream of fibrous elements moves in thedirection corresponding to that of the collecting surface whereby the fibrous elements of larger dimension are displaced forwardly from the stream for deposition onto the collecting sur-' face subsequent: to the deposition of the fibrous elements of smaller dimension passing through the drum.

9. In the method of forming a felted mat of fibrous elements of variable dimension in which the fibrous elements of smaller dimension form a layer substantially separated from the fibrous elements of larger dimension, the steps of advancing a collecting surface continuously in a longitudinal direction, issuing the fibrous elements in an endless stream from an outlet spaced above the dinally spaced apart relation from the fibrous elementsof smaller dimension originally present in the same stream. 7

10.'In the method of forming a felted mat of fibrous "t ts, the steps of advancing a collecting surface continuously in a longitudinal direction, issuing-the fibrous elements in an endless stream from an outlet spaced above the collecting surface and with the fibrous elements in uniform distribution across the collecting surface, intercepting the stream of fibrous elements between the outlet. and the collecting surface with a foraminous member having foramens dimensioned to ermit passage of fibrous elements of smaller dimension therethrough for continued travel by gravitational force to the collecting surface, and displacing the fibrous elements unable to pass through the foraminous member in a longitudinal direction for deposition onto a longitudinally spaced portion of the collecting surface in spaced apart relation to the fibrous elements of smaller dimension passing through the foraminous member.

11. In the gravity deposition of mixed fibrous elements in forming a mat, the steps of issuing the fibrous elements in a continuous stream in uniform distribution across a collecting surface from an outlet spaced above the collecting surface, separating the larger fibrous elements by screening from the smaller in the descending stream to permit the smaller elements in the stream to proceed downwardly for deposition onto the collecting surface, and displacing the larger elements in a longitudinal direction for deposition onto the collecting surface along a zone longitudinally adjacent to that where the smaller elements are deposited whereby the larger and smaller elements are incorporated into the structure as separate laminae.

12. In the manufacture of structures from mixed fibrous material, the steps of sprinkling discrete elements of the material of large and small dimension in admixture from an orifice towards a collecting surface on which a matrix' of the structure is to be formed, moving the collecting surface continuously in a longitudinal direction intercepting the larger elements during their. passage to to the surface, moving them longitudinally from their passage, and simultaneously depositing them with the smaller elements on the collecting surface whereby the larger elements are deposited longitudinally of the simultaneously deposited smaller elements and are therefore concentrated in a separate lamina from that formed by the smaller elements.

References Cited in the file of this patent UNITED STATES PATENTS 1,812,108 McCullough June 30, 1931 2,624,079 Duvall Jan. 6, 1953 2,635,301 Schubert et al Apr. 21, 1953 2,693,619 Goss Nov. 9, 1954 2698. 1 Clark Dec. 28, 1954

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