US2650395A - Structural wood unit - Google Patents

Description

Septl, 1953 P. DE ANGUERA l 2,650,395

STRUCTURAL WOOD UNIT Filed ne. 1e, 1948 ATTYS Patented Sept. l, 195.3

STRUCTURAL WOOD UNIT Philip de Anguera, Cincinnati, Ohio, assignor to Eva de Anguera, Cincinnati, Ohio Application December 16, 1948, Serial No. 65,657

(Cl. 2li-91) 1 claim. l

The present invention relates to improvements in structural wood units and is particularly directed to a prefabricated, composite unit which is especially useful as a floor panel and relates particularly to flooring manufactured from lower grades of lumber and which in use is to be subjected to intensive wearing actions and/or changes in temperature and moisture such as might exist by exposure to climatic conditions.

It is well known that wood readily absorbs moisture and conversely moisture quickly evaporates therefrom and in so doing considerable expansion and contraction, respectively takes place in the wood in the direction across its grain i. e. in the directions of the radial extensions of the medullary rays of the wood. It is also a generally recognized fact that the tensile strength and elastic resistance of wood is greatest along the grain in the longitudinal direction of its medullary rays. Longitudinal shrinkage of relatively hard, structural wood ordinarily is so small as to be considered negligible as it normallyv ranges from about 0.1 to 0.3 of one per cent from green or soaked to oven dry conditions.. Further it is a well known fact that edge grained lumber is approximately four times as resistant to wear as flat grain lumber and that good grade lumber for flooring is becoming extremely scarce and nearly prohibitive in its cost.

It has heretofore been suggested that flooring units be prefabricated from relatively narrow pieces of wood of various lengths by disposing said pieces in side by side rows and assembling the pieces inthe rows in end to end abutment, and splicing the unit together by longitudinally spaced, metal spiral dowels which are driven into prebored holes formed transversely through the assembled pieces. It has been found however that the material of the wood pieces around the metal dowels quite frequently splits across the wood grain due to the expansion and contraction of the wood in that direction, and in so doing, the material of the wood shrinks away from the dowels thus rendering less effective the dowel connections with the pieces which materially weakens the unit and frequently causes cracks to appear in the major faces of the unit.

It is Vtherefore an object of this invention to provide a driven, wood splicing means for a structural unit of the type described which precludes the splitting of the material of the united pieces around said splicing means and that also provides a means for prefabricating wood flooring units from substantially thinner stock.

Another object of the invention is to provide a metal connector key for a wood structural unit which is economically manufactured, and that effectively retains the wood pieces in fixed positions in the manufactured unit.

My improved structural wood unit therefore consists of thin metal connector keys adapted to be driven into longitudinally spaced prebored holes of uniform size formed transversely through the assembled wood pieces of a wood panel, said key having a width substantially greater than the diameters of the holes whereby its sides are sunk into the material of the pieces to retain them in fixed positions in the unit. Further the invention contemplates that the keys be so positioned in the prebored holes that their width dimensions are disposed substantially in the direction of the longitudinal extension of the medullary rays in the pieces which would place the keys with their major faces parallel to the major faces of the composite unit. It is also desirable that the grain of the wood pieces be substantially normal to the major faces of the unit so that the edge grain of the wood pieces is presented to the major wearing faces of the unit.

With the above and other objects in view, which Will be more readily apparent as the nature of the invention is better understood, this invention consists in the novel features of construction, combination, and arrangement of parts, hereinafter more fully described, illustrated in the accompanying drawing and defined in the appended claim.

Referring now to the drawing wherein like reference numerals indicate similar parts throughout the several views:

Fig. 1 is a fragmental, perspective View of a portion of my wood structural unit.

Fig. 2 is a cross sectional View taken on line 2 2 of Fig. 1; a suitable clamp used in manufacturing the unit being shown in dotted lines therein.

Fig. 3 is an enlarged cross section taken on line 3-3 of Fig. 2.

Fig. 4 is a fragmental, perspective View of a connector key for my unit.

Fig. 5 is a fragmental plan view of the stock from which the key may be most economically manufactured.

The embodiment of my invention comprises a number of wood pieces l0 of various lengths that are assembled in side by side relationship in longitudinal rows and which have their ends in abutment in the several rows. Any number of rows of pieces may be employed in fabricating the structural wood unit, but, as illustrated in Fig. l, I prefer to use approximately three rows of assembled strips and further employ relatively wide and thin pieces of wood that mayv have their grains extending substantially normal to the major faces of the unit. With particular reference to Figs. 1 and 3 it will be noted that the wood pieces in the unit have the longitudinal extension of their respective medullary rays Ill directed lengthwise in the pieces and therefore the greatest tensile strength of said pieces lies in said lengthwise directions and only a negligible shrinkage of the pieces or swelling will occur in said lengthwise directions.

The pieces so assembled are held together by a number of longitudinally spaced apart clamps. A suitable clamp for this purpose is illustrated by dotted lines I I in Fig. 2 and may have a pair of narrow jaws I2 and I3 which clamp the assembled strips between them by means of a screw lll that has left hand and right hand threads that cooperate with internally threaded lugs I5 and It depending from the jaws I24 and I3 respectively. A number of longitudinally spaced, transverse bores I'I of uniform diameter are formed through the assembled and clamped pieces by means of wood drills which may be aligned with the work by suitable jigs, or the like.

A thin connector key I8 preferably made from metal strip stock IIS, illustrated in Fig. 5, is driven endwiseA into each of the bores, and, as illustrated in Fig. 4, each of said keys has a round pilot end 20 formed thereon and an opposed flat driving end 2|. The connector key has a Width substantially greater than the diameter of the bore` into which it is to beV driven and as illustrated in Fig. 3 it will be notedy that the sides 22 and 23- of the connector key are forced into the material of the assembled pieces which thereby retains the pieces in xed positions in the unit.

As most clearly illustratedV in Fig. 3 the thin connector keys l8- are positioned in the respective transverse boresk il in the. unit with their widths extending in the general. direction ofthe longitudinal extensions. of the medullary rays I in the wood piecesv Ill, or, in other words the major faces of said keys are substantially parallel to the major faces of the composite wood unit. Thus the original hold power of the/keys, eiected. by driving them into the bores with their widths` extending in the general direction of thelongitudinal extension of the rays-in the wood pieces, will be retained. throughout thelentire period of usefulness of the unit, for, the keys cooperate with the characteristics of: the wood in that direction and, as has been. stated,

the material of the wood in said direction has the greatest tensile strength and elastic resistance and also no appreciable expansive and contractive qualities. Further as the greatest shrinkage and expansion of wood is in a direction across the grain, and the wood pieces Ill in the panels are generally disposed with their grain 24 running heightwise of said panel, contraction and expansion of the wood pieces will occur in both heightwise and transverse directions of the wood pieces, thus the greater component of such movement will be directed substantially vertically in the pieces as they are represented inV Fig. 3 whilst a lesser amount of the movement is directed transversely of the unit for the reasons indicated hereinbefore. As the keys are not set in their respective bores in generally vertical positions the material of the wood pieces around the bores is free to expand or contract vertically thus precluding splitting of the wood in said vertical vdirections around theV bores.

In the drawing the grains of the wood pieces have been indicated' by the. reference numeral 2li, and it will be noted that the grains of the wood pieces may all extend substantially normal to the major faces ofthe unit thereby present, ing the grain edge tothe major wearing surfaces of the unit to increase the useful life of the unit.

What is claimed is:

A composite structural unithaving. a plurality of elongate wood boards disposed in parallel rows and assembled in the rows in end to end'abutment, the predominant number of said boards having their individual grains disposed substantially normal to the major faces of the unit and` all of said boards having the longitudinalextent of their medullary rays disposed substantially lengthwise inthe unit, a number of longitudinally spaced bores of uniform d-iametersformed trans-Y versely through the assembled boards, ande a thin connector key extending through ther central portionv ofeach bore. andV having its sides wedged into the material of the wood on diametrically opposed sides of the board.k that lie in a line substantially normal tothe grains ofl the boards. I Y

PHILIP DE ANGUE-RA.

References Cited in the file of this patent FOREIGN PATENTS Number Country Date 399,024 Great Britain Sept. 28, 1933` 456,381 Great Britain Nov. 9, 1936l

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