US2439655A - Spliced lumber - Google Patents

Description

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April 13, 1948' H. c. GRAHAM 2,439,655

-SPLICED LUMBER Filed March 1e, 1944l ,Y'Ql- 2 3 f9.2. 54. k\\\\\\\ wg, 2 5 4.

fig. lP-l $159.5. 7

INVENTOR Patenteid Apr. 13, 1948 UNITED STAfrias PATENr t orner: a H Iaisas'ss a i SPLICED LnMBEa a IliarryC. au(lraliani,"1 Pittsburgh, Pa.,` assigner to Pittsburgh wScrew & Bolt Company, Pittsburgh, a l Pa., acorlporation otlennsylvana N "Application March 16, 1944SerialLNo. 526,693

coming lincreasingly scarce, expensive, and dilicultto secure. ,Long` lengths ofrheavy timber Afor use in piling, for-example;` are very difllcultto secure `and quite expensive.. Likewise, r `long lengths of heavy timber for use `in building r,or other constructions, are also diilicult to procure. n the other handincreased recognition `is being given to the use of wood in various 7construction operations, where heretofore `reinforced concrete has been employed, due tothe fact that for` many types of work, particularly where exposed: to rigorous climatic conditions and mechanical vibration, concrete has been found to spall, crack, `or disintegrate. `For example,` in railway, station `platforms and railwayr grade crossings, thereis an increasing demand for wood, notonly because ofthe greater service which it will render, but the ease with which itmay betakennpandreplaced for access to the` track or other purposes. 'Like- Wise there is anincreased demand for timber in lieu of concrete `for highway and other bridges.

The present` invention provides for f, the economical splicing together of smaller `pieces of lumber into a composite wholev which not only enables large or heavy timbers to be constructed, but enables in `many cases, inferior` ,grades of lumber to be very successfullyemployed, and the use of the present invention constitutes a factor in the conservation of valuable timber. t t It has heretofore been proposedto join smaller pieces of lumber together by spikes ortby nails,

butthis is not` adequatedueto the fact 'that l the nails are incapable of holding the Wood to- Attempts have ,been` made also` to accomplish the result by the` use of bolts andnuts, but here again difficulty has beentencountered, ,due tothe fact that the weaving yorvibrationof the wood tends to enlarge thehole through which `the bolt passes, While shrinkage of thewood oftenallows the tension under "which .the bolt is initially 10mm. (ci. et-913" placed to be relieved, `this latter result increasing the Weaving or relative movement `between the joined pieces, permitting the bolts to become increasingly loose.` Not only is this the case, but under conditions ofggcontinuedservice, the nuts will Vactually `move under vibration to a point where they drop completelymrf the bolt. As soon as anyffastener becomes loosein the` Wood, the initial bond, between `the fastener and the wood quickly disintegrates, and the wood actually seems toirecede from.` the zfastener. Experience has demonstrated therefore, that usual types of fastenings fall down `and areunsatisfactory in many` instances Where :these conventional fasteners wouldbeexpected to be satisfactory.

, According to theypresent invention, pieces of lumberrareisuccessfully spliced for service over manyyears of time. In the practice of the present invention, the two ormore pieces of wood which are to be` joinedvare temporarily secured or clamped together. Then they are drilled with a holeextending through one piece and at least part way,eifinot,entirely through the other. A dowel is then entered in this hole, the dowel having coarse spiraled ns or threads thereon', the angularpitch of which is not more than to the` longitudinal axis, oruis greater than 45 to a plane passing transversely `through the dowel. This pitch is such as to cause the dowel to be rotated as it is driveninto `the hole, the diameter of the hole being approximately the same, and preferably no greater than the root diameter of the `dowel. By reason `of this, the ydowel completely lls the hole `and the spiral threads or vanes compress the surrounding portions of the wood asthey cut a steeply spiraled thread into the wood. The dowel vis of a length such as toextend ycompletely through the piece into which it is iirstv entered and penetrate a substantial distance` into or entirely through the second piece, orl succeeding pieces. After the pieces have been doweled in thismannen the clamps ifemployed are released and the pieces will bepermanently held. One important factor contributing to the success of this means of securing the pieces together arises from the fact that ingdriving the dowel it `is impossible to strip the threads because each inward thrust of the dowel `underthe blow of a hammer produces aproper amount of rotation and it is impossibleto rotatethe dowel Without causing it to: penetratefurther intothe wood. Another factor is that the` threads in the wood, being interitted with the ,threads onethewdowel, have an angular pitch more nearly` approximating longitudinal keys than a succession of threads as is provided by ordinary wood screws or lag screws. AThis keying action serves to effectively resist the turning of the dowel except when accomplished by a driving force. In other words, the dowel cannot be turned as a screw is turned. Finally, a very important factor in the success of the present method that due toV the factthat when such'a'dowel is driven into wood, relative movement between the wood'and the dowel tends to rotate the dowel. Therefore any force tending to move two doweled pieces apartten'dsl to rotate the dowel, and since in separating,4 the votherwise forced in under impact or pressure.

' `As'they travel along the hole, they rotate, cutting two pieces move in opposite directions, each would j exert an opposite turning'force on the dowel; i. e., one of the two pieces would tend'to rotate the dowel in a clockwise direction,fwhilethesother' would tend to rotate it in a counter-clockwise direction, with the result that the forces would be neutralized and the'turning could not occur.

' My :invention may be frnore `f'ullyunderstood by referenceto the-accompanying `d'ra-wiirgs,"in which: 'l Y Y Fig.` lvisfa side elevation ofia dowlfde's-i'g'iie'dffor use-iinzthe presentfinventi'on.;

Figw2ais aitransverse section-in the'f'plane of A1751" face ofthe "dowel between the threads so that an initially tight hold is established between the tratingfthemannerf in fwliihftherpiecesare prey pared for :splicing:v Y Y Fig. i4 is a longitudinali-section '-thrdirglitwo piecesfof lumber joined' in en'd -toeend'l relatiom in accordance -Jwithf the presentinvention Fig.v5:is.fa topV plan viewfofanother'assembly, suchrasv afoor panel embodying my'invention, usefulfor bridge floors,` board-walks, station platforms, grade crossings, and felsewhere `where `a wooden floor of" this f characteri-isi desirable;

Fig. 6 isa transverse section in-lthe 'planeof line VI-'VIoffFigf' this View being on'a larger scale;

Fig. 7 is a view partly insideelev'ation `and partly in section of' still=anotherform of structure embodying my invention;

Fig.i8 isa schematic View illustrating the resolution of forces created in ther'dowel' when vthe pieces vtend to -separategthe viewbeing purely a schematic view;v and f Fig-9 is arview similar to Fi-gt ofla slightly modifiedy form f of panel.

Referring 'fir-sti to Figs. 1 andZ', thedowelI corn'- prises, in "its Apreferred embodiment, merely a length 4or rodl'iaving -a plurality of 'steeplyspiraled threads thereon. In Fig. 1, l2. designates the dowel and 4`SidesignaLtes the threads. The threadslform aniang'le of 45' or morelto a vertical vplane passing throughthe dowel. Thisv steep pitch ofthe threads causes the dowel to rotate when it is lbeing driven into the woo'dandthe pitch isso steep' th'atlthe threads v-will not serve to draw thezdo-welintothe wood when 'the dowel-is turnedlin the manner of'an ordinary wood screw. .The threadsmay"A be f formed on .the dowell either by .rolling o-r by twisting va ro'dofnon-circular crossisectionv about itsf'own axis. 'Theidowel per se is Ywell 'knownto those skilleslin the art, and alone forms noupa-rt of' the present'invention` According to fthe present invention, as illustratedfimFig. A`3,y the two or more pieces to b e joined together -are temporarily secured or clamped; In Fig, 4 designates one oftwo pieces and 5 designatesthe other. The'ylare'vheld i'nf any conventional rvicelike or `other clamp '6L After being clamped; oneforr-moreg prefer-ably Y a` F`plural ity of. spaced ."h'oles; l'l-are fdrilled 'therein, .the holes the dowel inopposite directions.

quired. Prior l'to .the presentinvnt'iogeitihas a steeply spiraled thread into the wood. The

'- woo'd' immediately around the hole is compressed andis'forcedintointimate contact with the surwood and the dowel.

After the dowels have been driven, the clamp or other holding means may be released, whereupon the-fpart'sfwillbefrmlwunited; :Ais herein- .before inaicatedfwhen tneyfrarefso nniteucrorces 'spready them s in `oppositel :directions Iasi indicated bythe straight arrowstendfto rotaterthedowl. The circularl arrows indicate that tneselfrees beingv exerted inioppositer direction-'f-teiid l oiifd'dte .'llliefi'rslit-is that the dowel Aeanriotfrcitate;"wherefore-thepieos cannot spread` apart. fnfno'hth'er .eriditihfof swelling and shrinking-ofthewoodthereforflhas no e'iect, andtest iristallations'h veestablislicd the pern'ianence--1V ofafsplice or @enit thus intended .to include eit'herfitlie pi'eiffi ments-'together infend It'o en'drelati application of my invention" fas appl' -ample to lengths of heavy` timber St piling, or elsewhere'iwhere' heavy;`

been'v proposed tozlap '.th'e 'ends'offth'ei piee'sgblt them together; and `then span? theintwthian annular'series` of stays or b'racesexteii loi'gii tudin'ally of theA assembly. With the @resent invention, 'muchA "more" permanen'te "and isatis'e factory results areiobtainedz'anditi isii-nhfecesry to use the externalA stays orfconnectors.

In Fig'. 4, l0 designates the upper of'tvvomein bers, and Il is the Iowerone.. As Sshownyltlie members .have the endsfthereoffcutiaway i-tolfrm overlapping tongues lila.V 'and VfHa remectively.

abuttingA andface Eto faice` relationfanfddril-led as described in connection with an'd the dowels designated I'Z areth'en'dr'iven..:Brefei ably they arev driven `from.:oppositefdirectiiinsfso as to; secure even.; more Veffective'i'holdlrgfpovvif.

InFi'gs 5xan'd '6, 'there"isillustratedafp catedL construction panel? designed fori-use Y tion platforms, crossings, 'boardwalllxsg lb Y hoors, or elsewhere whereesuch"constructioniis applicable. It may be assembled in 'manycasefsg from inferior or clieapergradesfo'f li'irdbe'r.V typical panel, for example, maybeuna'defim pieces of 2 x 4 setedgewiseahd"'seourei n", the manner hereinafter described, these' Vpiejcies ubeing either ofuniforin'length or being of'shotlngth. In Fig. 5, l'designates each of'the sever'alfpie'cs', andas indicated at la, theifull'lengt'hdf'sriiie'df the-piesmay'be less than thatotal length'of the panels so that some of the pieces are butted in end to end relation.

In making up the panels, a plurality, las for example 3 pieces d5, are rst clamped together and dowels I6 are entered into them, these dowels being the dowels illustrated in Fig. 1. In Fig. 1 they are illustrated as being entered from the left toward the right. The dowels are inserted by first drilling through the several pieces in the manner hereinbeforedescribed. After the first three pieces have been secured, two more additional pieces may be clamped to the assembly, to the left-hand side thereof, and the dowels I6 are entered, after rst drilling the pieces. These dowels extend not only through the two pieces which have been additionally added, but extend into that piece marked 15b, this being the innermost of the first group of pieces. After these pieces have been doweled, two more pieces are again applied, drilled and doweled, the dowels i6 passing through these two pieces Iand into the piece marked l5c. In this manner the panel is built up to any desired convenient width by adding additional pieces to the left-hand side of the panel. I have described the starting of the panel with three pieces followed by the addition of multiples of two, but this is purely arbitrary. It is necessary, however, to stagger the dowels as illustrated, both longitudinally and transversely in order that one dowel will not be driven into another, and in order to develop maximum strength. These panels are prefabricated at an appropriate assembling plant from which they are sent out into the field. In a structure such as that shown in Figs. 5 and 6, it is especially desirable to use dowels that do not have heads, in order that several pieces may be arranged in face to face contact.

In Fig. 7 there is illustrated another form of prefabricated structural unit useful for example in the construction of guard rails on highway bridges, or elsewhere where uprights are required. Whereas usual practice Would require the use of integral posts for this purpose, stronger and cheaper posts which incidentally may also be more artistic, are provided by the present invention. In Fig. 7 the post is illustrated as being composed of several pieces of lumber 20, 2|, and 22, which are illustrated as being of different lengths, but which may be of the same length. The lower ends of the several members terminate in a .common plane whereas the upper ends are stepped to improve the appearance of the unit. The several pieces are doweled in the man- In Fig. 9 there is disclosed a prefabricated structural panel similar to Fig. 5, but in which the dowels, 30, are of a length to extend continuously through all of the individual strips 3|. In either the form shown in Figi. 5 or Fig. 9, the dowels are close enough and heavy enough to provide load distributing bars to transmit and distribute heavy wheel loads for example over a considerable area.

While I am aware that it has heretofore been proposed to splice or secure the pieces of Wood together for extending the length or width thereof, and while I am also aware that dowels having only spiraled threads such as to enable them to be driven have heretofore been used in other elds, it has not heretofore been recognized that the use of these dowels for the splicing or joining of pieces of Wood to'form a structural unit would provide such a structural unit capable of standing up under extremes of weather and service condition over long periods of time without requiring attention, and wherein the parts cannot separate. In other words, my invention enables small pieces of lumber to be integrated into structural units which in turn may be employed in places where only expensive timber could heretofore be used, or enables timber to be used in locations where heretofore it would not be serviceable.

I claim as my invention:

A prefabricated wooden construction unit comprising a plurality of side-by-side rows of pieces of lumber of varying lengths, which pieces are arranged in end-to-end relationship in said rows, said unit having a plurality of holes ex tending transversely therethrough and spaced longitudinally thereof, a plurality of driven metallic screw threaded dowels extending through said holes, the diameter of said holes being approximately equal to the root diameter of said dowels, the threads of said dowels having suiiicient steepness of pitch so as to cause rotation of said dowels when driven through said holes.

HARRY C. GRAHAM;

REFERENCES CITED l The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Steiger J an. 8, 1842 Reinoehl et al. Feb. 7, 1911 Loetscher Sept. 10, 1929 Graham et al. Sept. 17, 1935 FOREIGN PATENTS Country Date Norway Feb. 17, 1908 Denmark July 2, 1934 Norway May 3, 1937 Germany Feb. 28, 1929 Number Number

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