US3835902A

US3835902A - Method of composing wide continuous bands of veneer

Info

Publication number: US3835902A
Application number: US00326627A
Authority: US
Inventors: A Elmendorf
Original assignee: Elmendorf Research Inc
Current assignee: Elmendorf Research Inc
Priority date: 1973-01-26
Filing date: 1973-01-26
Publication date: 1974-09-17
Anticipated expiration: 1991-09-17

Abstract

A method of composing veneer strips to form a continuous band in which proximal edges of adjacent pairs of strips may not be parallel. The strips are moved along a predetermined path and are separated to present gaps therebetween. The gaps are filled with a filler comprised of wood particles coated with a binder so that the mass of particles projects outwardly from at least one side of each gap. The particle mass in each gap is compacted under heat and pressure to the same thickness as the adjacent strips so that the filler is bonded to the edges of the strips. A flash of filler is formed on and is bonded to the surface of each adjacent strip at the edge of the strip to increase the connection between the filler and the strip. In a preferred embodiment of the invention, the particle masses are directed into the gaps by suction.

Description

Elmendorf Sept. 17, 1974 METHOD OF COMPOSING WIDE CONTINUOUS BANDS OF VENEER [75] Inventor: Armin Elmendorf, Palo Alto, Calif.

[73] Assignee: Elmendorf Research, Inc., Palo Alto, Calif.

[22] Filed: Jan. 26, 1973 [21] Appl. No.: 326,627

[52] US. Cl. 144/310 B, 117/2 R, 156/94 Primary ExaminerAndrew R. Juhasz Assistant ExaminerW. D. Bray Attorney, Agent, or FirmTownsend and Townsend [57] ABSTRACT A method of composing veneer strips to form a continuous band in which proximal edges of adjacent pairs of strips may not be parallel. The strips are moved along a predetermined path and are separated to present gaps therebetween. The gaps are filled with a filler comprised of wood particles coated with a binder so that the mass of particles projects outwardly from at least one side of each gap. The particle mass in each gap is compacted under heat and pressure to the same thickness as the adjacent strips so that the filler is bonded to the edges of the strips. A flash of filler is formed on and is bonded to the surface of each adjacent strip at the edge of the strip to increase the connection between the filler and the strip. in a preferred embodiment of the invention, the particle masses are directed into the gaps by suction.

13 Claims, 2 Drawing Figures METHOD OF COMPOSING WIDE CONTINUOUS BANDS OF VENEER In the manufacture of most Douglas fir and pine plywood, the veneers are cut on a lathe and are, therefore, referred to as rotary-cut. Large knots and wide splits are cut out at the lathe by clipping the veneer into relatively narrow strips. The strips are generally of various widths and slightly over 8 feet long for plywood S-foot long. The edges of veneer strips are often not exactly parallel to each other, and they are also generally slightly beveled since clipping does not produce a perfectly square edge. Consequently, the veneer strips must be jointed after drying in order to obtain the parallel, straight, and square edges required for edge gluing. Clipping and jointing results in a substantial loss of veneer so that the production of large sheets by edge gluing is costly.

Removing defects that are present when the veneer leaves the lathe results in waste of two types, namely, clipping loss resulting from removal of large open defects such as knotholes and splits, and jointing loss after drying the veneer. For a plywood manufacturer producing a million square feet of veneer per day, the veneer lost could have a value of $500 to $1,000 per day. While veneer waste may be chipped for paper manufacture, veneer in the form of plywood has a much greater value than the same amount of wood in the form of chips for paper.

Elmendorf US. Pat. No. 3,478,791, shows a method for filling knotholes and other open defects in veneer by sucking wood particles into the defects. I have found that if certain additional steps are taken beyond those shown in that patent, veneers can be held together edge to edge to produce a continuous band of veneer having a width equal to the length of the veneer strips. The resultant continuous sheet can be clipped into the desired sizes required for plywood manufacture. The edges of the veneer strips are not jointed and the waste incurred when the edges of each separate strip are sheared is eliminated. This results in a substantial economy in the manufacture of plywood. Furthermore, the labor of clipping the edges of the separate strips is eliminated. Assembling the separate strips into continuous full sized sheets and holding them together is referred to as composing.

Three methods of composing veneer are in use today. In one of these methods the edges of each strip of veneer are first jointed to make them square and parallel. Adhesive is then applied to the edges and these are then bonded together. Considerable waste is incurred in jointing the strips. Labor is involved in applying adhesive to the edges of the strips and in then bonding these together. In another method, fiberglass strings are bonded to the surfaces of the veneer. These extend across the grain and span the joints. The veneer edges are not bonded together and gaps may exist between the strips as these are generally not square or straight so that they do not fit together. The veneer strips are only loosely held by the strings and are readily pulled loose from the strings causing a machine breakdown so that this method of composing veneer is not satisfactory. In the third method. threads or strings are woven or stitched across the joints between the veneer strips. While the strips are more firmly held than with the glass fiber strips bonded across the veneer, the composing is still not satisfactory on account of open gaps at the joints, frequent lapping of veneer edges,and splits in the veneer. Splits in the veneer remain loose and open.

Composing veneer in accordance with my invention removes the deficiencies of each of the three methods described and all open defects are filled. My method results in considerable saving of veneer. A continuous band of veneer is formed at high speed with all openings filled at low cost, without gapsat the joints between veneer strips and without veneer loss.

My method of composing a continuous sheet of veneer out of strips of various widths consists of the following steps: Strips of veneer are placed in a horizontal plane and an end of each strip is brought into alignment. The strips are successively moved in the plane so that one edge of each strip is perpendicular to the direction of the movement across the grain of the wood. Gaps are then deliberately widened by separating the veneer strips at the joints to make the gaps at least wide enough to accommodate the larger particles of a filler, but not less than about I/ 16-inch wide. The filler, consisting of wood particles coated with a binder, is sucked into the gaps, the size of the particles being such that the particles can enter into the gaps at their narrowest point. Comminuted wood particles such as sawdust are satisfactory. About 8% to 40% of resin based upon the dry weight of the wood gives satisfactory results. The comminuted particles must be discrete and compressible, and when loosely assembled as a mass, they must be readily separated. Superior results are obtained when the binder has tack. The filler, as sucked into the gaps, has a thickness greater than that of the veneer strips. The filler is compacted under heat and pressure to about the same thickness as the veneer, and in compacting, it is bonded to the edges of the veneer strips. Furthermore, a flash of filler is formed on one surface of the veneer at the edges of the openings, and the veneer is slightly crushed at the edges. The flash extends over and is bonded to the face of the veneer, thereby greatly increasing the strength of the connection between the filler and the veneer. The resultant continuous band can be clipped into sheets of veneer of any desired width and length with very little loss.

The primary object of this invention is to provide a wood product and a method of making the same, wherein a plurality of strips of wood veneer are separated from each other to form gaps therebetween and the gaps are filled with masses of discrete, resin-coated, compressible particles so that, when the masses are compacted under heat and pressure, they are bonded to adjacent strips to form a unitary product having a given length and width.

Another object of this invention is to provide a wood product and method as described above, wherein the proximal edge margins of adjacent veneer strips need not be parallel with each other and the masses in the gaps also form flash to enhance the connection between the masses and adjacent strips.

Other objects of this invention will become apparent as the following specification progresses, reference being had to the accompanying drawing wherein:

FIG. 1 is a vertical section through apparatus for carrying out the method of the invention, illustrating the way in which veneer strips move past the apparatus; and

FIG. 2 is a fragmentary, perspective view of the wood product of the invention.

The apparatus shown in FIG. 1 may be used to suck the discrete coated particles into the gaps at the veneer edges after having previously separated the veneers to obtain a minimum gap. This gap may be widened so that a minimum gap may exist at one end of the strip of veneer, and the gap at the opposite end may be much greater. Veneer strips having non-parallel edges may be used. This is important since the edges of veneer commercially clipped at high speed are rarely exactly parallel, and the clipped edges may also not be square nor straight after drying. My method makes it possible to compose strips of veneer whose edges are not parallel or straight, or square into wide continuous bands of veneer without open areas or lapping of veneer at the joints.

Referring to FIG. 1, the veneer strips, 1, separated by gaps, 2, are brought into contact with a curved foraminous surface of the rotating cylinder, 3. Suction is provided around a portion of the perimeter of the concave surface of cylinder, 3. A partition, 4, excludes suction from the remainder of the cylinder. The veneer moves in contact with the cylindrical surface. The mass of discrete resin coated particles is shown at, 5, and this mass is maintained at a constant level by any conventional means such as an electric eye, not shown. The veneer is brought into contact with the stationary mass of discrete particles coated with a thermo-setting resin in the trough, 6. As the gap reaches the trough, 6, it is instantly filled with the particles. The air which is drawn through the gap carries with it some of the particles removed from this mass.

The mass of particles in each gap is sheared off the parent mass as the strips move and the mass is thicker than the thickness of the veneer, some of the excess having been removed by a cut-off brush, 7. By controlling the thickness of the particle mass 10 in each gap with cut-off brush, 7, the density of the compacted hardened filler is controlled. The particles that may adhere to the surface of the veneer are moved by the brush, 8. These fall down into the loose stationary mass, 5. The filler in the opening is then lightly compacted by a roller, 9.

The filler in the gap is compacted and hardened under heat and pressure as, for example, between heated steel belts, 11 and 12 disposed downstream of roller, 9 and on opposite sides of the strips. Flash, 13 (FIG. 2) is formed on the surface of each strip at the edges thereof due to over-filling of the corresponding gap, the flash lapping over such surface beyond the compacted mass. Also, the strip portions beneath the flash are crushed. The compacting and hardening of the filler is performed in a continuous operation by belts, 11 and 12 as the belts and strips move at the same speed.

I have found that adequate pressure can be obtained in this manner to ensure bonding of the compacted filler to the veneer edge margins and, moreover, that some of the filler forms a flash on one face of the veneer. This flash is an important feature of the process as it strengthens the connection between masses 10 and the adjacent strips and helps to hold the masses in place.

The resulting wood product 14 is shown fragmentarily in FIG. 2. This figure also shows that the proximal edge margins of a pair of adjacent strips need not be parallel.

Voids in the outer surface of each strip, 1 are filled as the strip moves past the mass of particles in trough, 6. The particles filling the voids are compacted under heat and pressure by belts, 11 and 12 and define regions, 15 as shown in FIG. 2.

Although the foregoing invention has been described in detail by way of illustration and example, for purpose of clarity and understanding, it is understood that certain modification may be practiced within the spirit of the invention as limited only by the scope of the appended claims.

In the claims:

1. A method of composing a plurality of strips of veneer comprising: moving the strips in edge-to-edge relationship along a predetermined path with each strip being spaced from an adjacent strip by a gap; filling substantially the volume of each gap with a compactable mass of discrete, binder-coated particles with the mass projecting outwardly from the gap; and applying heat and pressure to each mass to compact the same and to cure the binder thereof sufficiently to interconnect each pair of adjacent strips and to form a flash on the surface of each strip at the edges.

2. A method as set forth in claim 1, wherein the step of filling each gap includes drawing the mass into each gap by suction.

3. A method as set forth in claim 1, wherein said filling step includes moving the strips past a region containing a quantity of loose binder-coated particles, and drawing a mass of the particles out of the region and into each gap by suction as the gap moves past the region.

4. A method as set forth in claim 1, wherein is included the step of reducing the thickness of the portion of the mass projecting outwardly from each gap before the mass is compacted.

5. A method as set forth in claim 1, wherein each edge of a strip is crushed under the flash.

6. A method as set forth in claim 1, wherein the particles comprise sawdust, said binder being comprised of a thermosetting resin having a weight of at least 8% of the dry weight of the sawdust.

7. A method as set forth in claim 1, wherein each strip is stress relieved, said moving step including directing the strips about a curved path, said filling step including directing the particle mass into each gap as the strip moves about said curved path.

8. A method as set forth in claim 7, wherein is included the step of providing a region containing a quantity of said particles adjacent to the curved path, said filling step including drawing a mass of particles out of the region and into the gaps by suction.

9. A method as set forth in claim 1, wherein is included the step of filling voids in each strip as the strip moves along said path and as the gaps are successively filled, and compacting the particles in said voids under heat and pressure.

10. A method of composing veneer strips to form a continuous band in which the edges of adjacent strips may not be parallel with each other comprising: moving a plurality of strips of veneer in edge-to-edge relationship with each strip being spaced from an adjacent strip to present a gap therebetween; filling substantially the entire volume of each gap with a mass of discrete, binder-coated, compressible particles as the strips are moved so that the particle mass in each gap projects outwardly from one side thereof; and compacting and cluded the step of forming a gap between the edges of each pair of adjacent strips, the gap being wide enough at its narrowest point to accommodate the larger particles of the mass.

13. A method as set forth in claim 10, wherein is included the step of controlling the amount by which each mass projects outwardly from the corresponding gap to thereby control the density of the mass after it is compacted and hardened.

Claims

10. A method of composing veneer strips to form a continuous band in which the edges of adjacent strips may not be parallel with each other comprising: moving a plurality of strips of veneer in edge-to-edge relationship with each strip being spaced from an adjacent strip to present a gap therebetween; filling substantially the entire volume of each gap with a mass of discrete, binder-coated, compressible particles as the strips are moved so that the particle mass in each gap projects outwardly from one side thereof; and compacting and hardening the particle masses under heat and pressure to cause the masses to cure sufficiently to interconnect each pair of adjacent strips and to cause the surfaces of the masses to be substantially flush with the surfaces of adjacent strips.

11. A method as set forth in claim 10, wherein said compacting and hardening step includes forming a flash of the particles of each gap on the surface of each edge of adjacent strips to strengthen the connection therebetween.

12. A method as set forth in claim 10, wherein is included the step of forming a gap between the edges of each pair of adjacent strips, the gap being wide enough at its narrowest point to accommodate the larger particles of the mass.