CA1132892A - Apparatus for joining pieces of laminar material and in particular plywood core strips - Google Patents

Abstract

A B S T R A C T

An apparatus for joining plywood core strips comprises a feeding conveyor floor (1) for the wood strips to be jointed, a crowding conveyor floor (7) therefore and pressure elements (22,24), effective to press the wood strips against the feeding and crowding conveyor floors (1 and 7). Each pressure element includes a rod (22,24) having its front end (22f,24f) bent upwardly and supported by the machine frame (23, 25) through a kinematic train (22a,22b, 24a,24b) including a pneumatic cylinder (22c,24c) urging the rod (22,24) against the underlying conveyor floor (1, 7). Alignment means (26,26') including stop pawls (26') and sensors (34) controlling the actuation of the stop pawls (26') are provided to align the strips perpendicular to the feeding direction, as well as jointing material applying means (39-53).

FIGURE 2.

Description

1~3ZB9Z
_ 2 ~

Th-l~ inYention relate~ to an apparatu~ .~or joining piece~ of laminar material and in particular plywood core strips.
- ~lachines have been proposed which join together wood strips intended ~or m~{ing up the co~e plies o~
plywood, or ve~eex strip~ in general, by applying thereon the jointing material such as adhesive tapes or threads in a perpendicular directio~ to the strip edges~ a~d utilize a technique con~isting 1~ providing a succession of entraining con~eyor floor~ hereon the strips to be jointed edgewise are placed,and ~uitable pre~sure mechanisms capable o~ maintaining ~he strip~ in contact with such co~veyor ~loors; these ¢onve~or...~loors, which are compo~ed each of a serie~
o~ coplanar parallel con~eyor belts arranged in ~paced ~ide-b~side relatio~ship are characteristically driven at decreasing speeds, thersby the e~tr~inment o~ the wood strips to be joi~ted towards the jointing material applying mean~ iB perîormed with a progre~sive slowi~g 20 down of the ~oremost strips and consequent contacting therewith of the strips sequentially advanced from the ieeding cenveyor ~loor ~o the subsequent crowding co~veyor floor coplanar therewith.
E~own pre ssure mechanisms include pressing conveyor ~loors arranged above the entraining conveyor floors and adapted to press the wood strips against the underlying conveyor floors.
An example ~or thls technique is described, ~or example, i~ U5 Patent~ 2~705,514 or 2,4B8,759.

T~e use o~ pres~ing conveyor $100rs of the above d~scribed type had among others the ~ollowing dra~back~:
a) The strips to be proce~sed were clamped between the belts of the conveyor floor~ and e~rained by both of them 80 that a sliding movem~nt between the strips and the belts was dif~icult, thereby the ~rowding of the strip~ at t~e ~lower advancing conveyor floor wa~ e.ither impo3sible or caused excessive stresses both on the strips and the conveyor belt~.
b) The pressing conveyor floors require a complicated energy consumi~g driving and supporting meohanism, which occupied precious ~pace above the entraining conveyor floors, thereby preventing ade~uate arrangement of devices for the transverse slignment of the strips and the devices for the application of the ~ointing material on the strips~ in addition to the increased costs of the apparatus.
Thi~ invention is aimed at resolving the problems inherent in the removal of the above indicated draw-back~ from the apparatuses ~or joining pieces of laminar material to bet~er the efficency, increa~e the output and to reduce the manufacturing~ msi~tenance and operational costs.
~or the purpose there is provided according to the inve~tion sn apparatus for joining pieces of lamin~-r material, in particular wooden strips for ! plywood cores, including a plurality of successiv0 ¢oplanar oon~eyor iloors~ each consisting oi a series 3 of coplanar and parallel conveyor belt~ arr~lged in spa¢ed side-by-side relation~hip, said plurality o~
~ucces~ive coplanar conveyor floors including at least one feeding conveyor ~loor and at least one crowding con~eyor ~loor arr~nged a~ter the feeding conveyor floor and ha~ing it~ conveyor belt~ moving at a speed slower than that of the feeding conveyor ~loor belt~
S to allow the orowding thereon o~ the strip~ to be joi~ed~ and pressure mechani~m3 for holding the ~trip~
in contact ~ith the convegor floors~ wherein according to the improvement the apparatus is characterized ~n that the pressure mechanism~ comprise at lea~t one rod-like element arranged o~er at least paxt o* the long~tudinal extension o~ said succe~sive con~eyor floor3, ~aid rod-like ele~ent having a smooth lower ~urface ~acing the conveyor ~loors and mechanically controlled support mean~ for the rod-like element allo~ing said rod element to lie under co~trolled . pres~ure against the strips to be joined entrained by the conveyor ~loor~ alignment means arranb~ed betwee~
said rod-like element~ ~or aligning the strips to be ~oi~ed in a direction perpendicular to the longitudinal extension of the conveyor ~loor~ an~ joi~ting material applging means.
~ hese and other functlonal and constructional ~eature~ of the invention will be more apparent from the detailed de#cription which follows relating to a

2~ pos~ible prefe~red embodiment of the invention, where-in a single crowding conveyor floor i~ provided an~
.. th~ jointing material is a~ adhesive-coated thread, the embodiment being shown in the accompanying drawing~, in which:

3 Figure 1 i~ a diagrammatic plan view of the appa-ratus according to the inventio~; and ~ 5 -Figure 2 is a seotional v~ew o~ the apparatu~
t~en along the plane II-II o~ ~ig. 1.
~ Yith refere~ce to the cited drawing figures, there are indicated at 1 th~ belt~ which form the feeding conve~or floor, whereon an operator, located at the machine input end~ dispo~e~ the strips to be joined edgewise, such belts, being equipped with a belt tensioner 2, are run betwee~ drive pulleys, such as the one indicated at 3 i~ ~igure 2, which are ~eyed rigidly to a shaft 4~ and pulleys, ~uch as the one indicated at 5, also in ~igure 2, which. are idly ~ou~ted to the shaft 6.
The belt~ o~ the crowdi~g conveyor floor are indicated at 7 and are run between drive pulleys which are keyed r~gldly to the shaft 6-and pulleys which are idly mounted to a shaft 8, neither being shown in ~iguxe 2~ since they remai~ hidden respectively behind the pulley 5 and one o~ the splicing rollers which, as explained hereinafter, is also mounted to the ~h~ft 8; the belt~ 7 are equipped with a belt tensioner 9.
Bars 10 and 11, being carried by the structuxe 12 - o~ the machine, form a supporting and abutment element, re~pectively for the belts 1 and 7 of the feeding and crowding conveyor ~loors.
The motio~ is derived, for either con~eyor floors, ~rom an electric motor 13; a ~procket chain 14 ;. trans~er~ the motion to a sprocket wheel 15 which i~
keyed rigidly to the sha~t 4, a chain 16 transmitting the motion, through a speed reducer, between the sproc~ets 17 and 18; the latter is rigid with the sprocket wheel 19, wherefrsm motion is derived through _ 6 a chain 20 for the sprocket wheel 21, which is keyed riæidly to the sha~t 6.
Overlyin~ each of the belts 1 of the feedi~g conveyor floor and each of the belts 7 of the cro~dinæ
conveyor floor, are re3pective pressure elements which are operative to pre3s or bias the wooden ~trip~
against said conveyor ~loors, ~uch as to cause the same to mo~e under frictional en~agement. ~ach o~ the pressure elements overlying the ~eeding conveyor ~loor consist~ of a rod 22 kinem~tac~lly connected to a statio~ary arm 22a, which e~tends ~rom a crossmember 23 o~ the machine frame, through ~ rocker arm 22b pi~oted in 22k a~d on which the rod 22 is hinged in 22h by means o~ a lug 22i rigid therewith. ~he rod 22 i~ pushed towards the belt 1 by a pneumatic cylinder 22¢~ the pressure o~ which may be adjusted. ~rom the rod 22, there extends a lug 22d which i~ slidably guided by ~ork-liXe guides 22e, rigid with the arm 22a to preve~t lateral inclinations o~ rod 22. The front end 22f of the rod 22, bent upwardly to provide a ~laring inlet for the strips to be proce3~ed, i8 positioned æub3tantial1y at the wood strip ~ligning mechanism~ which will be e~plained h~reina~ter, wherea3 the rear end 22~ protrudes with respect to the belt 19 to e~tend o~er a contiguous end portion of the belt 7.
The rod 22 has a ~mooth lower surface faci~g the strips to be ~oined.
Quite similar to the above is the constructio~
of the pressure element~ or pushers overlyiDg the belts of the cro~ding con~-eyor floor. One thereo~
~hown in ~ig. 2 i~ formed by a rod 24 kinema~ically ~i32892 -- 7 _ supported by the stationary arm 24a, connect~d to the crossme~ber 25 throu~h a rocker arm 24b,.and pu~hed by pneumatic cylinder 2~c. From rod 24 a lug 24d ex-tends W~li chis slidablyguidedby the ~ork-likeguides 24e. It will be understood that the kinematic connection o~ the rod 24 is analoguous ~o that of rod 22. The front end 24f o~ the rod 24 i~ positioned substantially at the pulleys which are keyed to the ~haft 6, and the rear end 24~ is in a more forwardl~
loca~ed p~sition with respect to the jointing roller~
which will be de~cribed hereinafter.
The aligning mechanism ~or the strips to be joined together edgewise comprises a shaft 26 with ~top pa~ls 26' rigid therewith and shoWn in the drawing figures in a strip stopping position. ~he . rotational movement of the mechanism is controlled by ~E se known strip contacting sensors 27 and 28, which are adjustably supported by sliders 29 a~d 30 ~lidably supported on the guidss 31 and 32, ~ollowing consent by the sensors 33 and 34 which are removably attached to a rod 35, in co~formity with the modes explained hereina~ter, with re~erence to the machine operation.
~he jointing materiæl applying means comprise three mechanisms, indicated i~ ~ig. 1 at 36~37 and 38~ whereof the one indicated at 37 will be described in detail with re~erence to ~ig. 2. Such a mechanism consists o~ one of the roller~ 39 rigidly keyed to the shæft 8, which i~ driven to rot&te by a variable 30 ~peed electric motor 40 through a chain 41, and a rolier 42 which is suppo.rted idly on the arm 43, _ 8 _ ~ournaled and slidable on the shaft 44. The arm 43 carries~ moreover, a coil 45 o~ adhesiYe coated thread 46, constituting the jointing material ~ se known and ultrasonic welding dev~ce or sono-trode 47 effecting the melting of the adhesive by means of ~ ultrasolmds emitted by a generator included in the machine. At the end o~ the ~rm 43, there is provided a pneumatic cylinder 48 carried by a shaft 49, which performs the dual function of allowi~g the arm to be rai~ed~ and accordingly separation of the roller 42 from the sheet for carryin~ out ad~ustment operations, and of pressing the roller 42 again~t the sheet or strip with a force the amount of which is con~idered to be most ~uitable for proper operation.
15~or applyi~g the jointing material 46 to th~
. lower fac0 of the wood strip~, a coil 50 of adhesi~e material coated thread i~ provided which is carried b~ the arm 51 rigid with the slee~e 52, slidably mounted on the crossmember 53 of the machins structure;
the sono-trode 54 being also connected to said arm 51.
~ explained hereinabove, the deqcribed joi~ti~g material applying mechanisms are slidable transversely to the machine~ by virtue of the sleeve 52 and cross member 53~ thereby they can be carried at any point of the roller~ 39 for applying the jointing material to the most suitable looation.
~ inally, there is indicated at 55 a ~ se known sensor adapted to detect the pas~ing by of the wood strips~ and controlling a microswitch not shown provided on the supply side o~ the electric motor 40;
&aid sensor 55 being supported by a slider 56 slidable ~i3Zb~9~i:
_ g _ on the guide 32.
~he appar~tus operates as follows.
Onl~ when ~e fir~ ~trip laid by the operator onto the belts ~ o~ the feeding conveyor floor contact~ both se~sors 33 and 34, the strip is suffi-ciently aligned i.e. perpendicular to the longitudinal feeding direction o~ the apparatus a~d only then a conse~t i~ emitted by them for the raising rotation of the stop pawls 26' of the aligner 26~ following a short time interval which is controiled by a timer operati~e to permit the strip to rea~h contact with said stop pawls 26'. Re~erse sinking rotatiGn of the stop pawls 26~, to block the passing of the ~ollowing #trip which has to be aligned, occurs a~ the trail~ng edge of the ju~t considered strip pa~se~ under the sensor 27.
It will be appreciated that the raising and si~king rotatio~ of the stop pawls 26' is obtained by the action of a pneumatic cylinder (not sho~n), which acts on the ~haft 26 through a crank mechanism causing rotation through about 90 of this shaft irA
one or the other direction. The cyli~der is actuated through a ~E se known controlling electric circuit controlled b~ the above described ~ensors 33,34 a~d 27.
It will be understood that, when the ~trip to be entrained by the feeding con~eyor floor is not aligned~
i.e. is not perfectly perpendlcular, one of the senso~s 33 or 34 i8 not actuated and no consent is given for the raising rotation of the stop pawls 26'.
3 Consequertly the strip is further entrained by the feeding conveyor floor until it reaches one of the ~3Z89z ~top pawl~ 26' with one point thereof which i~
prevented from moving further and slides with respect to the conveyor floor while the other portion oi the strip is ~urther entrained until alignment with the perpendicular direction occurs and also the other of the sensors 33 or 34 is actuated, giving thereby consent ~or the rai 9ing rotation of the stop pawls 26' after the described short time interval allowing the relevant strip portion to travel the ~hort distance between the sensors 33 or 34 and the stop pawl~ 26~, such distance being normally shor~er than the width of the processed strip. 0~ continuing it~
advance movement and with the stop pawls 26' in blocking positio~ the considered strip gets i~to contact with the sensor 28 which-releases the rai~ng rotation of the stop pawls 26' ~uch as to allow the following strip to pass past it only i~ consent is gi~en by the se~sor~ 33 and 34, i.e. only if the following strip is in contact with both sen~ors 33 and 34, i.e. is ali~ned. An automatic control cycle of ~he aligner is thus established.
As the strips are transferred from the ~oading con~eyor floor to the crowding conveyor floor, owing to the ~ower speed of the lattsr with respect to the former, the strips tend to crowd i.e. to approach each other. It will be apparent that the prsssure elements 22,24 pressi~g the wood strips against the belts of the con~eyor floors ensure agai~st the risk of exce~sive slipping of the same with respect to the 3 belt3, and a~-oid overlapping of two con ecutive strips or cli~bing o~ one ~trip above the other.

il;~Z892 In ~act, it will be appreciated that the pre~sing action of the pre~ing rods 22,2~ which are - preferably made of steel should not sxceed a cer~ain degree,si~ce in the crowding con~eyor floor a slipping o~ the proces~ed strips wlth respect to the con~eyor belts of thè conveyor ~loors should be allo~ved, as hereinPfter described. On the other hand the pressing action should not be excessively low, since otherwise in the feeding conveyor an uneven slipping o~ the ~trips wilh re~pect to the conveyor belts may occur and an inclination thereof with respect to the alignment direction may happen after the align-ment deYice 26, 26' Moreover in the crowding conveyor floor the climbing of the strips one o~er the other ~hould be prevented as above described. It will be appreciatedthat this controlled pressure de~ree of the pres~ing rod~ 22~24 against the strips to be processed i~
obtained on the one hand by the weight itself of the ~0 pre~sing rods 22~24 and the roclcing support the~eof and on the other hand by the controlled pressing -action o~ the inclined pneumatic cylinders 22c and 24c. It will be under~tood that the point in which the cylinders 22c and 24c act i~ selected in the area where the danger of ~rregular slipping or ¢limbing of the strips is greater. In fact, owing .. to the oscillatable support o~ the pressing rods 22 and 24 on the respective rocker axms 22b and 24b the pres~ing action is greater in the area of the point of action of the piston rods of the cyli~ders 22c and 24~. ~oweYer this localized greater pressinæ

ll;~Z892 action i~ compen~ated by the horizont~l component of the inclined piston forcet which create~ an anti-cloc~qi~e movament o~ rotation about the pivot 22h, 22k and 24h, 24k as will appear clear to tnose ~kllled in the art~
As the first strip while sliding get~ in contact with sensor 55, the latter is raised and releases the ~tarting of the motor ~0, which drives the jointing materiRl applyin~ rollers 3~, which by rotating with a lower peripheral speed t~an the crowding conveyor floor, exert on the strip a braking action, causing a slippage thereof with re~pect to the ¢o~Yeyor belt~ 7, and conseauently a deceleration thereof such as t¢.produce contact with the oncomni~g following strip~ to thu~ produce the continuous sheet or ply which is join~ed.
Upon rotation o~ the roller 39, the adhesiYe-coa~ed threads 46 are progressively pressed on the one side by the driving roller~ 39 and on the other side by ~he.idle rollers 42 against the advancing jointed strips, which, ~hile advanci~g under the - ¢ontrolli~g action o~ the rollers 39 cause rotation o~ the idle rollers 42, thereby to exert a pulling a¢tio~ on the adhesive-coated threads which are thu~
25 unwound ~rom their coils 4~ and 50 and caused to pas~
through the heating device~ 47 and 54 thereby to cause t~e adhesive coating of the thread to attain a melted condition be~`ore being ~pplied to the strips by the pressing action thereon o~ the rollers 39 and 42~
3 It will be understood that the heating devices 47 and 54 may be of con~entional electric resistance type.

11;~289Z

Under normal conditions, the motor 40 is kept movi~g constantly on account of the achie~ed continuity o~ the sheet or ply u~1der the sensor ~5.
However, i~ for a reason whatever, the strip suppiy i8 momentarily discontinued, and a gap is formed under the sensor 55, then the sensor 55 is lowered and the motor 40 stops to cause the jointing material applying rollers 39 to stop thereby stopping in turn the contacti~g sheet or ply. Si~ce said rollers 39 will only resume their moYement upon arrival o~ a ~resh ~trip, it will be apparent how no discontinuity is created in the jointed sheet or ply.
It is to be noted that ~he output speed o~ the joi~ted ply~ and accordingly the machine own output, ~s proportional to the ~peed of the joint material applying rollers 39, which as me~tioned above al~o perform the ~unction of friotional rollers.
In ~act, as Yisible in ~ig. 1 rollers 39 are large enough to per~orm such double function, taking into account that t~e adhesiYe threads are sufficiently thin for the purpose.
~ i~ally~ provision i~ made in the controlling ¢ircuitry for cancelling the automatic cycle de~cribed aboYe, when it i8 desired to remove an undesired strip processed by the machine.
The machine de~cribed hereinabove ~ill obviously include means for supplying the strips to this apparatu~, a cutter for reducing the resulting continuous ply to size, and discharging and quic~
3 pili~g means.
The inYention as described hereinabo-ve is suscep-tible to many mod-i~ications and variations~
all o~ which fall within the scope of this inventive concept: for example, the adhesive provided on the splicing ~hxead could be melted by mean~ o~ the heat genexated by a spirally wound, and possibly encased, electrical re~istor, throug~l the inside whereof the thread is pa~sed in the presence of a co~pre~sed air jet .

Claims (8)

The embodiments of the invention in which an exclusive property or privileges is claimed are defined as follows:

1. An apparatus for joining pieces of laminar material, in particular wooden strips for plywood cores, including a stationary frame structure, supported on said frame structure a plurality of successive coplanar conveyor floors having a longitudinal extension, each consisting of a series of coplanar and parallel conveyor belts arranged in spaced side-by-side relationship, said plurality of successive coplanar conveyor floors including at least one feeding conveyor floor and at least one crowding conveyor floor arranged after the feeding conveyor floor and having its conveyor belts moving at a speed slower than that of the feeding conveyor floor belts to allow the crowding there-on of the strips to be joined, and pressure mechanisms for holding the strips in contact with the conveyor floors, wherein the pressure mechanisms comprise at least one rod-like element arranged over at least part of the longitudinal extension of said successive conveyor floors, said rod-like element having a smooth lower surface facing the conveyor floors and suspension means for the rod-like element and wherein said suspension means comprise for each rod-like element an articulated link connection allowing limited translatory and angular adaptation movements for said rod-like element and wherein said pressure mechanisms include a controlled pressure fluid opera-ted piston-cylinder group acting on said rod-like element allowing said rod element to adapt itself under controlled pressure against the strips to be joined entrained by the conveyor floors, the apparatus further comprising alignment means arranged between said rod-like elements for aligning the strips to be joined in a direction perpendicular to the longi-tudinal extension of the conveyor floors and jointing material applying means.

2. An apparatus according to claim 1 wherein said articulated link connection comprises a rocker arm arranged at a distance from said rod-like element and extending normally in the same direction as said rod-like element and having an end thereof hingedly supported on the stationary frame structure, a lug rigid with said rod-like element and projecting therefrom towards said rocker arm, said rocker arm having another end thereof hingedly connected with said lug at a distance from said rod-like element and a pressure fluid operated piston-cylinder group of adjusta-ble pressure type-having one extremity thereof hingedly connected to the stationary frame structure and the other opposite extremity thereof hingedly connected to said rod-like element at a distance from said another end of said rocker arm thereby to allow limited angular and translatory adaptation of said rod-like element to the thickness irregularities of the processed laminar material while maintaining a substantially constant evenly distributed pressure thereon.

3. An apparatus according to Claim 2, charac-terized in that said piston-cylinder group is arranged inclined with reject to said rod-like element and wherein said other opposite extremity of the piston-cylinder group is arranged near a rearward end of said rod-like element.

4. An apparatus according to Claim 1, charac-terized in that said alignment means comprise a shaft extending transverse to said rod-like elements near the forward end thereof, at least two stop pawls arranged in the reach of the path of the strips to be processed and fixed on said shaft at a distance from each other and defining the alignment direction for said strips, at least two inlet sen-sors located before said stop pawls and adapted to release the opening movement thereof only when both are in contact with a strip to be processed, a third sensor being provided after said stop pawls and adapted to release the closing movement of said pawls only when the trailing edge of a strip passes thereunder.

5. An apparatus according to claim 4, characterized in that after the third sensor a fourth sensor is provided which is adapted to give consent for the opening of the stop pawls when contacted by the passing by strip and preventing the opening of the stop pawl in the absence of the strip, and timer means delaying the opening action of said stop pawls.

6. An apparatus according to claim 1, characterized in that said jointing material applying means comprises a shaft extending transverse to the longitudinal direction of the apparatus and arranged at the end of the last conveyor floor thereof, a plurality of jointing material applying driven rollers keyed on said shaft, a variable speed motor for ro-tating said shaft and driving said rollers with a selected speed, a sensor before said rollers arranged in the path of said strips, said sensor being adapted to consent actuation of said motor when contacted by a strip and to stop said motor when out of contact with a strip to be processed, a plurality of pressing rollers arranged opposite said driven rollers to press said strips passing therebetween and allow-ing said driven roller to exert a braking action thereon, sup-port means for said pressing rollers, said support means in-cluding a swingable arm, coils of jointing material carried by said arm and heating means for said jointing material.

7. An apparatus according to claim 6, characterized in that said jointing material is an adhesive-coated thread and said processing means are an ultrasonic device for heating said adhesive-coated thread.

8. An apparatus according to claim 6, characterized in that said jointing material is an adhesive-coated thread and said processing means are electric resistor based heating means for the adhesive-coated thread.