US2831223A - Plywood - Google Patents

Description

April 22, 1958 J. c. DE sHAzoR, JR 2,831,223

PLYwooD Filed June l0, 1957 fuif/v7- PLYWOOD James C. De Shazor, Jr., Portland, Oreg., assignor to Columbia Basin Plastics Company, a corporation of Oregon Application June 10, 1957, Serial No. 664,525

8 Claims. (Cl. 20-91) This invention relates generally to plywood and more particularly to a method and means for assembling pieces of veneer wood sheets to form an inner ply to be used in making a plywood board from a plurality of plies.

Since thev number of plies, over three, used in making a finished plywood board does not eiect the practice of this invention, this disclosure is limited to a board with three plies. In making such a yboard a higher quality veneer sheet may be laid on a flat support with the downward side being the side which will be one of the faces of the finished board and the upper or inner side covered with glue. Then narrower pieces of poorer quality veneer woodvsheets are laid side rby side across the wet glue surface of the first outer sheet and a second outer sheet with an upper finish face and a lower face to which wet glue is applied is laid over the narrow pieces. When the three ply board so formed is pressed together and dried in an oven the result is a three ply board of plywood.

In assemblying the pieces making the inner ply of the board in the above way a great deal of time is lost if care is taken to fit the narrow pieces close together. If the narrow pieces are not carefully placed extra large voids will be formed and a great amount of glue is required to make a reasonably solid board. When the glue used becomes excessive difliculty is experienced in venting from the plywood board as it is being dried the volatile matter formed in the drying process. I-f these gases are not vented While the structure is under pressure, they may themselves develop such pressure that when the structure is released from the press in which it was dried the gases will expand and separate the plies in spots to form raised so-called blisters on the finished board and thus degrade the board. If the amount of glue used is not excessive the volatile gases will vent to the edges of the board through the glue seams between the narrow pieces of the inner ply while the glue is still soft.

It is the principal object of this invention to provide a method for assembling narrow strips of veneer wood to form a continuous sheet from which an inner ply of a plywood board can be cut to a desired size.

lt is a second object of this invention to provide locking means for holding the narrow strips in the form of a continuous sheet after such assembly.

It is a third object to form such a continuous sheet from narrow strips in such a way that the paths to the edges of the plywood boards through the seams between the narrow strips of the continuous strip will not be blocked and prevent the venting of volatile gases during the drying of the board.

How these and other objects are attained is explained in the following description referring to the attached drawing in which- Fig. 1 is a plan view of a three ply board having an inner ply in accordance with this invention.

Fig. 2 is an edge elevation of the board of Fig. l.

Fig. 3 is a fragmental section viewed along the line 3 3 of Fig. l.

.United States Patent() 2,831,223 Patented Apr. 22, 1958 Fig. 4 is a fragmental plan viewed along the line 4-4 of Fig. 3.

Like reference numerals refer to like parts in the several figures of the drawing.

Referring now to the drawing the completed plyboard 11 of Figures 1 and 2 is seen to include a top ply 12 a bottom ply 13 and an inner ply 14 all formed of strips of veneer wood. The top ply 12 and the bottom ply 13 are each shown to be formed of a single piece while the inner ply 14 is formed of three narrower strips 15, 16 and 17 held together by multiples of clips 18.

It is to -be noted that the inner ply 14 is fundamental to the present invention since it is made up of the veneer wood strips 15, 16 and 17 held together by clips 18. Also basic to the present invention are the clips 18 and the method of their application.

A clip 18 is basically rectangular in plan having substantially parallel ends 19 and parallel sides`20. The corners are rounded as shown and each of the sides 20 have formed near each of their ends a pair of latches 21 standing outwardly from the sides 20. Clips 18 have approximately parallel top and bottom surfaces spaced about one half the thickness of the inner ply 14 of board 11.

As typically shown in Figures 3 and 4 to apply a clip 18 a recess 23 is sunk in adjacent faces of strips 16 and 17 in a direction perpendicular to the common seam 22 to the depth of clip 18 and to a width equal to the spacing of sides 20 thereof for a length at least equal to the spacing of the ends 19 thereof. Then an adhesive is applied to the inner face of recess 23 on the lower face of clip 18 and clip 18 is pressed into recess 23 to be ush with the surfaces of strips 16 and 17. The pressure of insertion of clip 18 into recess 23 causes latches 21 to cut into strips 16 and 17 to secure strips 16 and 17 in substantial abutment at seam 22.

It should be noted that clip 18 blocks seam 22 for only half the depth thereof so that seam 22 continues to form a continuous opening laterally through board 11 for venting volatile matter from the interior of board 11 when it is being held under pressure in an oven while the glue dries.

While clips 18 can be made of any material strong enough for the purpose, can -be of almost any outline in plane and can be secured in place with any form of latches and With any compatible adhesive, I prefer to use a clip with the shape disclosed made of one of the many suitable organic plastics which can be dipped in a compatable solvent to form a surface adhesive which will penetrate between the wood grains to tix the clip in place.

Having listed some of the objects of my invention, illustrated and described a preferred form in which my invention may be practiced and explained the virtue and use thereof, I claim:

l. A plywood board having an inner ply including a pair of ply strips in substantial abutment along a seam extending transversely between opposite edges of said board, said ply strips being secured together across said seam by a flat clip sunk into adjacent surfaces of said strips across said seam for substantially one half only of the depth of said strips, whereby when said inner-ply is pressed between two other plies of said board with hot iluid glue substantially lling the spaces between said plies the half depth of said seam below said clip will serve to maintain said seam as a continuous vent to the outside for volatile matter within said board while said glue is drying.

2. For use as an inner ply of a plywood board a continuous ply comprising a pair of ply strips in substantial abutment along a seam extending transversely between opposite edges of said ply, said ply strips being secured together across said seam by a at clip sunk into adjacent 3 surfaces of said strips across said seam for substantially less than the full thickness of said strips whereby there will remain under said clip a substantial part of said seam uninterrupted by said clip.

3. The continuous ply of claim 2` for use Aas an inner ply of a plywood board in which said clip is formed with mechanical means for latehing said clip to said two ply strips.

4. The continuous ply of claim 2 in which said clip is adhesively secured to each of said two ply strips.

S. The continuous ply of claim 3 in which said clip is adhesively additionally secured to each of said two ply strips.

6. The continuous ply of claim 4 at an intermediate stage in the construction thereof in which said clip is formed of an organic plastic material covered with a compatable solvent to penetrate said two ply strips adjacent said -clip in the wood grain structure of said strips to unite said clip with said strips.

7. The continuous ply of claim 5 at an intermediate stage in the construction thereof in which said clip is formed of an organic plastic material covered with a compatable solvent to penetrate said two ply strips adjacent said clip in the wood grain structure of said strips to unite said clip with said strips.

8. The continuous ply of yclaim 5 in which said clip is formed of an organic plastic material and in which the surface of said clip adjacent said ply strips is separated from said ply strips -by a layer including the porous surface of said ply strips lled with the organic plastic material of said clip.

No references cited.

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