CA2433487C - Floorboard and locking system therefor - Google Patents

Abstract

A floorboard and an openable locking system therefor comprise an undercut groove on one long side of the floorboard and a projecting tongue on the opposite long side of the floorboard. The undercut groove has a corresponding upwardly directed inner locking surface at a distance from its tip. The tongue and the undercut groove are formed to be connected by adjoining boards being brought together and snapped together.

Description

i CA 02433487 2003-07-01 _ ` - -" 'I'h~ ONwzdes~ Pa~~c-rt PCT/SE02/00042 ;POT r J...¾'MV'U0nIV AppGtcabk2n, s i .,.

u FLOORBOARD AND LOGKING SYSTEM THEREFOR

The present invention relates to a locking svstem for mechanical joinin.g of floorboards and floorboards having such a locking system.
Technical Field The invention is particularly suited for floorboards which are based on wood material and in the normal case have a core of wood and which are i.ntended to be mecha-nically joined. The following description of pri,or-art technique and the objects and features of the invention will th.erefore be directed at this field of application and, above all, rectangular parquet floors which are joined on long side as well as short side. The invention is particularly suited for floating floora, i.e. floors that can move in relation to the base. However, it should =15 be emphasis ed that the invention can be used on all types of existing hard floors, such as homogen.eous wooden floors, wooden.floors with a lamellar core or plywood core, floors with a surface of veneer and a core of wood f ibre, thin laminate floors, floors with a plasta.c core and the like. The invention can, of course, also be used in other types of floorboards which can be machined with cutting tools, such as subfloors of plywood or particle board. Even if it is not preferred, the floorboards can after installation be fixed to the base.
Technical Background of the Invention Mechanical joints have in a short time taken great market shares mainly owing to their superior laying pro-perties, joint strength and joint quality. Even if the floor according to WO 9426999 as described in more detail below and the floor marketed under the trademark Alloc have great advantages compared with traditional, glued floors, further improvements are, however, desirable.

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Mechanical joint systems are very convenient for joining not on.ly of laminate floors but also wooden floors and composite floors. Such floorboards may consist of a large number of different materials in the surface, core and rear side. A.s will be described below, these materials can also be included in the different parts of the joint system, such as strip, locking element and tongue. A solution involving an i.ntegrated strip which is formed according to, for ex.ample, WO 9426999 or WO 9747834 and which provides the horizontal joi.n.t, and also involvin.g a tongue which 'provides the vertical joint, results, however, in costs in the form of material waste i.n connection with the formingqof the mechanical joint by machining of the board material.
For optimal function, for instance a 15-mm-thick parquet floor should have a strip which is of a wl.dth which is approximately the same as the thickness of the floor, i,e. about 15 mm. With a ton.gue of about 3 mm, the amount of waste will be 18 mm. The floorboard has a normal width of about 200 mm. Therefore the amount of material waste wi11 be about 9%. Tn general, the cost of materaal waste will be great if the floorboards consist of expensive materials, if they are thick or if their format is small, so that the number of running meters of joint per square meter of floor wi1_1 be great.
Certainly =Clhe amount of material waste can be reduc-ed if a strip is used which is'in the form of a separate-ly man.ufactured aluminium strip which is already fi.xed to the floorboard at the factory. Moreover, the aluminium strip can in a number of applications result in a better and also more inexpensive joint system than a strip machined and formed from th.e core. However, the alurninium strip is disadvantageous since the in.vestment cost can be considerable and extensive reconstruction of the factory may be necessary to convert an exs.sting traditional pro-duction line so that floorboards with such a mechanical joint system can be produced. An advantage of the prior-i.Si?.
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-- . 3 art aluminium strip is, however, that the starting format - of the floorboards need not be changed.
When a stri.p produced by machining of the floorboard material is involved, the reverse is the case. Thus, the format of the floorboards must be adju.sted so that there is enota.gh materi.al for formzng the strip and the tongue.
For laminate floors, it is often necessary to change also the width of the decorative paper used. All these adjust-ments an.d changes also require costly modi.fications of production equipment and great product adaptations.
In addition to the above problems relating to undesirable material waste and costs of production and product adaptation, the strip has disadvantages in the form of its bein.g sensitive to damage during transport and installation.
To sum up, th.ere i.s a great need of providing a mechanical joint at a lower production cost whi.le at the same time the aim is to maintain the present excellent properties as regards laying, taki.ng-up, joint quali.ty and strength. With prior-art solutions, it is not pos-sible to obtain a low cost without also having to lower the standards of strength and/or laying function. An object of the invention therefore is to indicate solu-tions which aim at reducing the cost while at the same time strength and function are retained.
The invention starts from known floorboards which have a core, a front side, a rear side and opposite joint edge portions, of which one is formed as a tongue groove defined by upper and lower lips and having a bottom end, and the other is formed as a tongue w.ith an upwardly directed portion at its free outer end. The tongue groove has the shape of an undercut groove with an opening, an inner portion and an inner locking surface. At least parts of the lower lip are formed integrally with the core of the floorboard and the tongue has a locki.ng sur-face which is designed to coact with the inner locking surface in the tongue groove of an adjoining floorboard, j, ; .R.4 ~).'_t.... i , ; . ,t_:,, ~ I ' .~~~. ~.}~.},~jj'~ ~j ~~
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PCT/SE02f00042 when two such floorboards are mechanically join.ed, so ~ that their front aides are located in the same surface plane (HP) a.nd meet at a j oznt plane (VP) d.irected per-pendicular thereto. This technique is disclosed in inter alia WO 9627721, DE-A-1212275 and JP 3169967, which will be discussed in more detail belowo Defore th.at, however, the general technique regard-ing floorboards and locking systems for mechanical lock-ing-together of floorboards will be described as a back-ground of the present invention.
Description of Prior Art To facilitate the understandi.ng and description of the present invention as well as the knowledge of the problems behind the invention, here follows a descra.ption of both the basic construction and the function of floor-boards according to WO 9426999 and WO 9966151, with. refe-rence to Figs 1-10 in the accompanying drawingse In applicable parts, the foliowin:g description of the prior-art techns.que also applies to the ernbodiments of tb.e pre-sent invention as described belowa Fi.gs 3a and 3b show a floorboard 1-according to WO 9426999 from above and from below, respectivelyn The board 1 is rectangular with an upper side 2, an underside 3, two opposite long sides vaith joint ed.ge porti.ons 4a and 4b, and two opposite short sides with joint edge por-tions 5a and 5bo The joint edge portions 4ag 4b of the long sides as well as the joint edge portions 5a, 5b of the short sides can be joined mech.anically without glue in a direction D2 in Figa 1c, so as to meet in a joint plane VP (marked in Figo 2c) and so as to have, in their lald state, their upper sides in a common surface plane HP (marked in Fig 2c) o Zn the shown embodiment, which is an example of floorboards according to WO 9426999 (Fi.gs 1-3 in the accompanying d.rawings), the board 1 has a factory-mounted plane strip 6 which extends along the en.tire long side }r) i} .09 1': 2 0 2 PCTfSE02/00042 10_01-2003 s 4a and which is made of a flexible, resilient aluminium sheet. The strip 6 extends outwards beyond the jo.int , plane VP at the joint edge portion 4a. The strip 6 can be attached mechan.ically according to the shown embodiment or else by glue or i.n sorne other manner. As stated in said documents, it is possible to use as material for a stri.p that is attached to the floorboard at the factory, also other strip materials, such as sheet of some other metal, aluminium or plastic sections. As is also stated in WO 9426999 and as described and shown in WO 9966151, the strip 6 can instead be formed integrally with the board 1, f or instance by suitable machining of the core of the board 1.
The present invention i.s usable for floorboards where the strip or at least part thereof is integrally formed with the core, and the invention solves special problems that exist in the joining, disconnection and production 'of such floorboards. The core of the floor-board need not, but is preferably, made of a uniform material. The strip, however, is always integrated with the board, i.e. it should be formed on the board or be factory-mounted.
In known embodiments according to the above-mention-ed WO 9426999 and WO 9966151, the width of the strip 6 can.be about 30 mm and the thickness about 0.5 mm.
A similar, although shorter strip 6' is arranged along one short si.de 5a of the board 1. The part of the strip 6 projecting beyond the joint plane VP .is formed with a locki.ng element 8 which extends along the entire strip 6. The locking element 8 has in its lower part an operative locking surface 10 facing the joint plan.e VP
and having a height of, for instance, 0.5 mm. In laying, this locking surface 10 coacts with a locking groove 14 which is made in the underside 3 of the joint edge por-tion 4b of the opposite long side of an adjoining board 11 . The strip 6' along the short side is provided with a corresponding locking element 81, and the joint edge por-'iil':-.ii:.l`7 1~n:::Ur P= 'T`r:..f IL'trJ4.C(.J...I:,O.
-- ) .. ). ' , =: . . . ''f~::'. 'c1 ~1~1 'l~'YLP' V~`-_ ez~:i~~; ~E ~~r+'1;I,1~a PCT'tSE02100042 ` 6 tion 5b of thz opposite short side has a corresponding locking groove 14'. The edge of the locking grooves 14., 14' facing away from the joint plane VP forms an opera-tive locking surface 10' for coaction with the operati.ve locking surface 10 of the locking element.
For mechanical joining of long sides as well as short sides a?so in the vertical direction (direction Dl in Fig. ic), the board 1 is also along its one long side (joint edge portion 4a) and its one short sz.de (joint edge porti.on 5a) formed with a laterally open recess or tongue groove 16. Th.i.s is defined upwards by an upper lip at the joint edge portion 4a, 5a an.d downwards by the respective strips 6, 61. At the opposite edge por-tions 4b, 5b, there is an upper recess 18 which defines a lockin.g tongue 20 coacting with th.e recess or tongue groove 16 (see Fig. 2a) , Figs la-lc show how two long sides 4a, 4b of two such boards l, 1' on a base U can be joined wi.th each other by downward angling by pivoting about a centre C
close to the intersection between the surface plane HP
and_the joint plane VP, while the boards are held essen-tially in contact with each other.
Figs 2a-2c show how the short sides 5a, 5b of the boards 1, 1' can be joined together by snap action. The long sides 4a, 4b can be joined by means of both methods, whereas the joining of the short sides 5a, 5b - after laying of the first row of floorboards - is normally car-ried ou.t merely by snap action after the long sides 4a, 4b have first been joined.
When a new board 1' and a previously laid board 1 are to be joined along their long si.de edge portsons 4a, 4b according to Figs 1a-lc, the long side edge portion 4b of the new board 1' is pressed against the long side edge portion 4a of the previ.ously laid board 1 according to Fig. 1a, so that the locking tongue 20 is inserted into the recess or tongue groove 16_ The board 1' is then angled down towards the subfloor FT according to Fig, 1b.

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~ ~~~~~t omic.9 PCT/SE02/00042 The locking tongue 20 enters completely the recess or ~ tongue groove 16 while at the same time the locking ele-ment 8 of th.e strip 6 snaps into the locking groove 14.
During this downward angling, the upper part 9 of the locking elernent 8 can be operative and perform guiding of the new board 1' towards the preva.ously laid board 1.
In their joined position according to Fig. 1c, the boards 1, 1' are certainly locked in the D1 direction as well as the D2 direction along their long side edge por-tions 4a, 4b, but the boards l, 1' can be displaced rela-tive to each other in the longitudinal direction of the joint along the long sides (i.e. direction D3).
Figs 2a-2c show how the short side edge portions 5a and 5b of the boards 1, 1' can be joined mechanically in the D1 as well as the D2 direction by the new board 1' being displaced essentially horizontally towards the pre-viously lai.d board 1. This can in particular be carried out after the long side of the new board 1' has been joined, by .inward angling according to Figs la-c, with a previously laid board 1 in an adjoin.ing row. In the first step in Fig. 2a, bevelled surfaces of the recess 16 and the locking tongue 20 cooperate so that the strip 6' is forced downwards as a direct consequence of the bringing-together of the short side edge portions 5a, 5b.
During the final bringing-together, the strip 6' snaps up when the locking element 8' enters the locking groove 141, so that the operative locking surfaces 10, 10' on the Iocking element 8' and in the locking groove 141 engage each other.
By repeating the operations shown in Figs 1a-c and 2a-c, the entire floor can be laid without glue and along al1 joint edges. Thus, prior-art floorboards of the above type can be joined mechanically by first, as a ru1e, being angled downwards on the long side and by the short sides, when the long side has been locked, being snapped together by horizontal displacement of the new board 1' along the long side of the previously laid board 1 rlr.;..rl...n9 1 i:~7 :.~T3~Y~ i:~Il3F)'=.::t~I::f?:;.._. ._ .
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._ 8 (direction D3). The boards f, 1' can, wi.thout the joint - being damaged, be taken up again in reverse order of laying and then be laid once more. Parts of these laying principles are applicable also in connection with the present in.vention.
To function optimally and to allow easy layin.g and taking-u.p again, the prior-art boards should, after bei,ng joined, along their long sides be able to take a position where there is a possibility of a minor play betwee?-~. the 7.0 operative locki.ng surface 10 of the locking element and the operative locking surface 10' of the locking groove 14. However, no play is necessary in the actu.al butt joint between ~he boards in the joint plane VP close to the upper side of the boards (i,e. in the surface plane 1.5 HP). For such a position to be taken, it may be necessary to press one board against the other. A more detailed descripti.on of this play is to be found in WO 94269990 Such a play can be in the order of 0~01-0.05 mm between the operative locking surfaces 10, 10' when pressing the 20 long sides of adjoining boards against each other. This play facilitates entering of the locking element 8 in the locking groove 14, 14' and its leaving the same. As men-tioned., however, no play is required in the joint between the boards, where the surface plane HP and tra.e joint 25 plane VP intersect at the upper side of the floorboards.
The joint system enables displacement along the joint edge ~.n the locked position after joining of an optional side. Therefore laying can take place in~ man.y different ways which are all variants o.~ the three bas~c 30 methods:
- Angl~,ng of long side and snapping in of short side.
- Snapping in of long side - snapping in of short side.
- An.gling of sh.ort side, upward anglir~.g of two boards, 35 displacement of the new board along the short side edge of the prev=ous board and, finally, downward angling of two boards, = f ~ I , ~ 5; ~? =~ ~~. r.y... 1 1 ~~ I c~ r. i.. + , ~.
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rC'`.ot r.~ cir.T,anic:ir.:,.~ti!~~E~l~$d~~a7~4~~:~s;zdcu :"_Yi, a 77 PCTlSE02/00042 _ s ' The most comrnon and safest laying method is that the - long side is first angled downwards and locked against another floorboard. Subsequently, a displacement in the locked position takes place towards the short side of a third floorboard, so that the snapping-in of the short side,can take place. Laying can also be made by one side, long side or short side, being snapped together with another board. Then a displacement in the locked position takes place until the other side snaps together with a third board. These two methods require snapping-in of at least one side. However, laying can also take place with-out snap action. The third alternative is that the short side of a first board is angled inwards first towards the short side of a second board, which i.s already joined on its long side with a. third board. After this joining-together, the first and the second board are slightly angled upwards. The first board is displaced in the upwardly angled position along its short side until the upper joint edges of the first and the third board are in contact with each other, after which the two boards are jointly angled downwards.
The above-described floorboard and its locking sys-tem have been very successful on the market in connection with laminate floors which have a thickness of about 7 mm and an aluminium strip 6 having a thickness of about 0.6 mm. Similarly, commercial variants of the floorboards according to WO 9966151 shown i.n Figs 4a and 4b have been successful. However, it has been found that this tech-nique is not particularly suited for floorboards that are made of wood-fibre-based material, especially massive wood material or glued laminated wood material, to form parquet floors. One reason why this known technique is not suited for this type of products is the large amount of material waste that arises owing to the machining of the edge portions to form a tongue groove having the necessary depth.

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One more known design of inechanical locking systems for boards is shown in GB-A-1430423 and Figs 5a-5b in the accompanyin.g drawingse This system is basically a tongue-and-groove joint which is provided with an extra holding 5 hook on an extended lip on one side of the tongue groove and which has a correspondin.g hold.ing ridge formed on the upper side of the tongue. The system requires consider-able elasticity of the lip provided with the hook, and dismounting cannot take place withou.t destroying the 10 joint edges of the boards< A tight fit makes manufacture difficul.t and the geometry of the joint causes a large amount of material waste.
WO 9747834 discloses floorboards wi.th different types of inechanical locking systems. The locking systems which are intended for locking together the long sides of the boards (Figs 2-4 11 and 22-25 in the document) are design.ed so as to be mounted and disrnounted by a con-necting and angling movement, while most of th.ose intend-ed for locking together the short s3des of the boards (Figs 5-10) are designed so as to be connected to each other by being translatorily pushed towards each other for con.nection by means of a snap lock, but these locking systems at the short sides of the boards cann.ot be dis-mounted with.out being destroyed or, in any case, damaged.
Some of the boards th.at are di.sclosed in WO 9747834 an.d that have been designed for connection and dismount-ing either by an angular motion or by snapping together (F.zgs 2-4 in WO 9747834 and Figs 14a-c in the accompany-ing drawings), have at their one edge a groove and a strip projecting below the groove and extending beyond a joint plan.e where the upper sides of two join.ed boards meet. The strip is designed to coact with an essenti.ally complementarily formed portion on the opposite ed.ge of the board, so that two similar boards can be jo.ined. A
common feature of these floorboards is that the upper side of the tongue of the boards and the corresponding upper boundary surface of the groove are plane and ~
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'~ ~ ~~~~rr i~~~~c~~~ PCT/SE02100042 parallel with the upper side or surface of the floor-boards. The connection of the boards to prevent them from being pulled apart transversely of the joint plane is obtained exclusively by means of locking surfaces on the one hand on the underside of the tongue and, on the other hand, on the upper side of the lower lip or strip below' the groove. These locking systems also suffer from the drawback that they require a strip portion which extends beyond the joint plane, which causes material waste also within the joint edge portion where the groove is formed.
For mechani.cal joining of different types of boards, in particular floorboards, there are many suggestions, in which the amount of material waste is small and in which producti.on can take place in an effi.ci.ent manner also when using wood-fibre- and wood-based board materials.
Thus, WO 9627721 (Figs 5a b in the accompanying drawings) and JP 3169967 (Figs 7a-b in the accompanying drawings) disclose two types of snap joints which produce a small amount of waste but which h.ave the drawback that they do not allow easy dismounti.ng of the floorboards. More-over, in these systems it is not possible to use h.igh locking angles so as to reduce the risk of pulli.ng apart.
Also th.e joint geometry is disadvantageous with regard to snapping-in, which requires a considerable degree of material deformation., and with regard to manufacturing tolerances where large surface portions must be accurate-ly adjusted to each other. These large surface portions which are in contact with each other also make a di.s-pl.acement of the floorboards relative to each other in the locked position difficult.
Another known system i.s disclosed in. DE-A-1212275 and shown in Figs 8a-b in the accompanying drawings. Thi.s known system is suited for sports floors of plastic mate-rial and cannot be manufactured by means of large disk-shaped cutting tools for forming the sharply undercut groove. Also this known system cannot be dismounted with-out the material having so great elasticity that th.e - r!~_!ded b !:= 0 PN.:9.0 x;

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upper and lower lips round the undercut groove can be - greatly deformed while bei.ng pulled apart. This type of joint is therefore not suited for floorboard.s that are based on wood-based-based material, if high-qualityy joints are desireda FR-A-2675174 discloses a mechan.ical joint system for ceramic tiles which have complementarilv formed opposite edge portions, in which case use is made of separate spri.ng clips which are mounted at a distance from each other and which are formed to grasp a bead on the eage portion of an adjoining tilee The joint system is not designed for dismou.nting by pivoting, which is obvious from Fige l0a and, in particular, Fig. 10b in the accom-pany.ing drawings.
Another system is disclosed in DE 20001225U1., where the lower lip yi.eldso This prior-art construction, how-ever, is very sensitive and has great disadvantages because the lower lip has been weakened by the locking groove.
Also DE 19925248 discloses a system wi.th an upwardly directed locking element.
As is evident from that stated above, prior-art systems have both drawbacks and a.dvantagesa However, no locking system is quite suited for rational production of floorboard.s with a Iocking system which is optimal as regards production technique, waste of material, laying and taking-up function and which besides can be used for floors which are to have high qu.ality, strength and f_unc--tion in their laid stateo An object of the present invention is to sat7sfy this need and provide such an optimal locking system for floorboards and such optimal floorboardsa Another object of the invention is to provide a snap joi.nt whi.ch can be produced in a rational, manner. Further objects of the invention are evid.ent from that stated above as well as from the following descri-ptiona Jir-1õ'V
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Summary of the Invention A floorboard and an openable locking system therefor comprise an undercut groove on one long side of the floorboard and a projecting tongue on the opposite long side of the floorboard. The undercut groove has a corresponding upwardly directed inner locking surface at a distance from its tip. The tongue and the undercut groove are formed to be brought together by snap action. Preferred embodiments are also dismountable by an angling motion which has its centre close to the intersection between the surface planes and the common joint plane of two adjoining floorboards.
The undercut in the tongue groove of such a locking system can be produced by means of disk-shaped cutting tools whose rotary shafts are inclined relative to each other to form first an inner part of the undercut portion of the groove and then a locking surface positioned closer to the opening of the groove.

Further advantages and features of the invention are also evident from the following description.

Before specific and preferred embodiments of the invention will be described with reference to the accompanying drawings, the basic concept of the invention and the strength and function requirements will be described.

The invention is applicable to rectangular floorboards having a first pair of parallel sides and a second pair of parallel sides. With a view to simplifying the description, the first pair is below referred to as long sides and the second pair as short sides. It should, however, be pointed that the invention is also applicable to boards that can be square.

High Joint Quality - ~v . ntlr:!~,iSJ.:,P PCT'/SE02/00042 i0-O1.-2003 By high joint quality is meant a tight fit in the locked position between the floorboards both verti.cally and horizontal ly. It should be possible to join the floorboards without very large visible gaps or diffe-, 5 rences in leve7: between the joint edges in the unloaded as well as in the normally loaded state. In a high-quality floor, joint gaps and differences in level should not be greater than 0o2 and 0.1 mm respectively.
Upward Angling about Joint Edge In general, it should be possible to angle the long side of a floorboard upwards so that the floorboards can be released. Since the boards in the starting position are joined with tight joint edges, this upward anglingg must thus also be able to take place with upper joint edges in contact with each oth.er and with rotation at the joint edge. This possibi.lity of upward angling is very important not only when changing floorboards or moving a ,floor. Many floorboards are trial-laid or laid incorrect-ly adjacent to doors in corners etc. during installa-' tion. zt is a serious drawback if the floorboard cannot be easily released without the joint system bei.ng damag-ed. Nor is it always the case that a board that can be an.gled inwards can also be angled up again. In connection with the downward angling, a slight downwards bending of the str.ip usually takes place, so that the locking e1e-ment is bent backwards and downwards and opens. If the joint system is not formed with'suitable angles and radii, the board can after laying be locked in such man-ner that taking-up is not possible. The short side can, after the joint of the long side has been opened by upward angling, usually be pulled out along the joint edge, but it is advantageous i.f also the short side can, be opened by upward angling. This is parti.cularly advan-tageous when the boards are long, for instance 2.4 m, which makes pulling out of short sides di.fficult. The i upward angling should take place with great safety with-, 2 01) 3-0 1==951 1p:' i:,~`p;,s:ia'll~uzici~ ':-~C~_ iYi"~7`~>`,:!~'~~i?
,.,xa.~[x=Fn~t~: [i1":F,75.... ~._ .~ .1 -C:.iiCsl!llF.?L2:3'=:~Cl'j~;~~j'~ OI'!'i.ciCxs ~- - - 10-01-2003 out the boards getting stuck and pinching each other so as to cause a risk ot the locking system being damaged.
Snapping-in It should possible to lock the short sides of floorboards by horizontal snapping-in. Thi.s requires that parts of the joint system be flexible and bendabl.e. Even if inward angling of long sides is much easier and quicker than snapping-in, it is an advantage if also the long side can be snapped in, sirnce certain layi.ng operations, for i.nstance round doors, require that the boards be joined horizontal3y. In case of a snappable joint, there i.s a risk of edge risi.ng at the joint if the joint geometry is inappropriate.
Cost of Material at Long and Short Side zf the floorboard is, for instance, 1.2*0.2 m, each square meter of floor surface will have about six times more long side joints than short side joints. A large amount of rnaterial waste and expensive joint materials are therefore of less importance on short side than on long side.
Horizontal Strength For high strength to be achieved, the locking ele-ment must as a rule have a high locking angle, so that the locking element does not snap out. The locking ele-ment must be h.igh a.nd wide so that it does not break when subjected to high tensile load as the floor shrinks in winter owing to the low relative humidity at this time of the year. This also applies to the material closest to the locking groove in the other board. The short side joint should have higher strength than the long side joint since the tensile load during shrinking in winter is distributed over a shorter joint length along the short side than along the long side.
yertical Strength It should be possible to keep the boards plane when subjected to vertical loads. Moreover, motion in the joint should be avoided since surfaces that are subjected .
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Di.splaceabi.lity To mak.e it possi.ble to lock all four sides, it must be possible for a newly laid board to be displaced in the locked position along a prevs.ously lai.d board. This should take place using a reasonable amount of force, for instance by d.ri.ving together using a block and hammer, without the joint edges being damaged and ws.thout the joint system having to be formed with visible play hori-zontally and verticallyo Displaceabi.lity is more zmpor-tant on long side than on short si.de si.nce the friction is there essentially greater owing to a longer joint.
Production Tt should be possible to produce the joint system rationally using large rotating cutting too3s having extremely good accuracy and capacity, Measur.ing A good function, product3on tolerance and quality require that the joint profile can be conti.nuously measured and checked. The critical parts in a mechanical joint system should be designed in such manner th.at producti.on and measurement are facilitated. It should be possible to produce them with tolerances of a few hundredths of a millimetre, and it should therefore be possible to measure them with great accuracyP for i.nstance in a so-called profile projector. If the joint system is produced with linear cutting machining, the joint system will, except for certain production tolerances, have the same profile over the entire edge portion. Therefore the joint system can be measured with great accuracy by cutting out some sam.ples by sawing from the floorboards and measuring them in the profi.le projector or a measuring microscope. Rational production, however, requires that the joint system can also be measured quickly and eass.ly without destructive methods for instance usi.ng gages. This is facili.tated if the ;;=Q L~.; :zl d.c,c:ut. ,i_i.:. 2 Ll'_..: ..rY..tdc:r' _,: Qi~.i.dc, CA 02433487 2003-07-01 _ , - 10-01-2003 critical parts in the locking system are as'few as possibl.e.
Optimisation of Long and Short Side For a floorboard to be man.ufactured optimally at a minimum cost, long and short side should be opti.mised in view of their different properties as stated above. For instance, the long side should be optimised for downward angling, upward angling, positioning and displaceability, wh.ile the short side should be optimi.sed for snapping-in and high strength. An optimally designed floorboard should thus have different joint systems on long and short side.
Possibility of Moving Transverselv of Join.t Edge Wood-based floorboards and floorboards in general which contain wood fibre swell and shrink as the relative humidity changes. Swelling and shrinking usually start from above, and the surface layers can therefore move to a greater exten.t than the core, i.e. the part of which th.e joint system i.s formed. To prevent the upper joi.nt edges from rising or being crushed in case of a high degree of swelling, or joint gaps from arising when drving up, the joint system should be constructed so as to allow motion that compensates for swelling and shrink-ing.
The lnvention The invention is based on a first understanding that by usin.g suitable production methods, essentially by machining and using tools whose tool diameter signi-ficantly exceeds the th.ickness of the board, it is pos-sible to form advanced shapes rationally with great accu-racy of wood materials, wood-based boards and plastic materials, and that this type of Tnachining can be made in a tongue groove at a distance from the joint plane.
Thus, the shape of the joint system should be adapted to rational production which should be able to take place with very narrow tolerances. Such an adaptation, however, is not allowed to take place at the expense of other S..!)i fly ), ..
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~----' 18 important properties of the floorboard and the locking system.
The inventi.on is also based on a second under-standin.g, which is based on the knowledge of the require-ments that must be satisfied by a mechanical joint sys-tem for optimal function. This understandingg has made it possible to satisfy these requi.rements in a manner that has previously not been known, viz. by a combination of a) the design of the joint system with., for instance, specifi.c angles, radii, play, free surf aces and ratios between the different parts of the system, and b} optimal utilisation of the materi.al properties of the core or core, such as compression, elongation, bending, tensile strength and compressive strength, The invention is further based on a third under-standing that it is possible to provide a joint system at a lower production cost wh.i.l.e at the same time func-tzon and strength can be retained or even, i.n some cases, be improved by a combination of manufacturing technique, joint design, choice of materials and optimisation of long and short sa.des.
The invention is based on a fourth understanding that the joint system, the manufacturing technique and the measuring technig,que must be d.eveloped and adjusted so that the critical parts requiring narrow tolera.nces shoul.d, to the greatest possible extent, be as few as possible and also be designed so as to allow measuring and checking in continuous production.
According to a first aspect of the invention, there are thus provided a locking system and a floorboard with such a locking system for mechanical joining of all four sides of this floorboard in a first vertical directi.on DI., a second horizontal direction D2 and a third direc-tion D3 perpendicular to the second horizontal direction, with corresponding sides of other floorboards with iden-tical locking systems.

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The fl.oorboards can on two sides have a disconnect-= ible mechan.ical joint system, which is of a known type and which can be laterally displaced in the locked posi-tion and locked by inward angling about joint edges or by horizontal snapping. The floorboards have, on the other two sides, a lockin.g system according to the invention.
The floorboards can also have a locking system according to the .invention on all four sides.
At least two opposi.te sides of the floorboard thus have a joint system which is designed according to the invention and which comprises a tongue and a tongue groove defined by upper and lower lips, where the tongue in its outer and upper part has an upwardly directed part and where the tongue groove in. its inn.er and upper part has an undercut. The upwardly directed part of the tongue .and the undercut of the tongue groove in the upper lip have locking surfaces that counteract and prevent hori-zontal separation in a direction D2 transversely of the joint plar~.e. The tongue and the tongue groove also have coacting supporting surfaces wh..ich prevent vertical sepa-ration in a direction Dl parallel with the joint plane.
Such supporting surfaces are to be found at least in the bottom part of the tongue and on the lower lip of the tongue groove. In the upper part, the coacting locking surfaces can serve as upper supporting surfaces, but the upper 1ip of the tongue groove and the tongue can advan-tageously also have separate upper supporting surfaces.
The tongue, the tongue groove, the lockin.g element and the undercut are designed so that they can be manufactur-ed by machining using tools which have a greater tool diameter than the thickn.ess of the floorboard. The tongue can with its upwardly di.rected porti,on be inserted into the tongue groove and its undercut by essenti.ally hori-zontal snapping-in, the lower lip being bent so that the upwardly di.rected portion. of the tongue can. be i.nserted into the undercut. The lower lip is shorter than the upper lip, which facilitates the possibility of forming =~iot~~: tl' -ts~' y 1~ 7... : V: l:if,: r.=i,=,. ' ~j ~j : ~j7'1 =
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y"=,iW':L"!.C'~.@:Li }7~.' (1j ii . CLJC.c an undercut with a locking surface which has a relatively high inclination to the surface plane of the board and which thus gives a high horizontal locking force, which can be combined with a flexible lower lip.

5 According to a second aspect of the invention, the floorboard has two edge portions with a joint system according to the invention, where the tongue with its upwardly directed portion both can be inserted into the tongue groove and its undercut by a snap function and can 10 leave the tongue groove by upward angling while at the same time the boards are kept in contact with each other with their upper joint edges.

Alternatively or furthermore, the tongue can be made flexible to facilitate such snapping-in at the short 15 side after the long sides of the floorboard have been joined. Thus, the invention also relates to a snap joint which can be released by upward angling with upper joint edges in contact with each other.

According to a third aspect of the invention, the 20 floorboard has two edge portions with a joint system which is formed according to the invention, where the tongue, while the board is held in an upwardly angled position, can be snapped into the tongue groove and then be angled down by a pivoting motion about the upper joint edge.

The lower lip is shorter than the upper lip so as to enable greater degrees of freedom when designing the undercut of the upper lip and especially its locking surface.

According to another aspect of the invention, there is provided a flooring system comprising a plurality of identical floorboards, which are mechanically joinable at a 20a joint plane, said floorboards having a core, a front side, a rear side and opposite joint edge portions, of which one is formed as a tongue groove, which is defined by upper and lower lips and has a bottom end, and the other is formed as a tongue with an upwardly directed portion at its free outer end, the tongue groove, seen from the joint plane, having the shape of an undercut groove with an opening, an inner portion and an inner locking surface, and at least parts of the lower lip being formed integrally with the core of the floorboard, and the tongue having a locking surface which is formed to coact with the inner locking surface in the tongue groove of an adjoining floorboard, when two such floorboards are mechanically joined, so that their front sides are positioned in the same surface plane and meet at the joint plane directed perpendicular thereto, wherein the inner locking surface of the tongue groove is formed on the upper lip within the undercut portion of the tongue groove for coaction with the corresponding locking surface of the tongue, said locking surface being formed on the upwardly directed portion of the tongue to counteract pulling-apart of two mechanically joined boards in a direction perpendicular to the joint plane, wherein the lower lip has a supporting surface for coaction with a corresponding supporting surface on the tongue, said supporting surfaces being intended to coact to counteract a relative displacement of two mechanically joined boards in a direction perpendicular to the surface plane, wherein all parts of the portions of the lower lip which are connected with the core, seen from the point where the surface plane and the joint plane intersect, are located outside a plane which is positioned further away from said point than a locking plane which is parallel therewith and which is tangent to the coacting locking surfaces of the tongue groove and the tongue where these are most inclined relative to the surface plane, wherein the coacting 20b supporting surfaces of the lower lip and of the tongue, seen parallel with the surface plane, are positioned at a distance from, and closer to the joint plane than to the free outer end of the tongue, wherein all parts of the portions of the lower lip which are connected with the core are shorter than the upper lip and terminate at a distance from the joint plane, the lower lip is flexible, the upper lip is more rigid than the lower lip, and the upper and lower lips of the joint edge portions are formed to enable connection of a laid floorboard with a new floorboard by a pushing together motion essentially parallel with the surface plane of the laid floorboard for snapping together the parts of the locking system during downward bending of the lower lip of the tongue groove.

According to another aspect of the invention, there is provided a floorboard for providing the flooring system as described herein, by mechanical joining of the floorboard with similar floorboards at a joint plane between said floorboard and said adjoining similar floorboard, said floorboard having a core, a front side, a rear side and opposite joint edge portions, of which one is formed as a tongue groove, which is defined by upper and lower lips and has a bottom end, and the other is formed as a tongue with an upwardly directed portion at its free outer end, the tongue groove, seen from the joint plane, having the shape of an undercut groove with an opening, an inner portion and an inner locking surface, and at least parts of the lower lip being formed integrally with the core of the floorboard, and the tongue having a locking surface which is formed to coact with the inner locking surface in the tongue groove of said adjoining floorboard so that their front sides are positioned in the same surface plane and meet at the joint plane directed perpendicular thereto, wherein the inner locking 20c surface of the tongue groove is formed on the upper lip within the undercut portion of the tongue groove for coaction with the corresponding locking surface of the tongue, said locking surface being formed on the upwardly directed portion of the tongue to counteract pulling-apart of said two mechanically joined floorboards in a direction perpendicular to the joint plane, wherein the lower lip has a supporting surface for coaction with a corresponding supporting surface on the tongue, said supporting surfaces being intended to coact to counteract a relative displacement of said two mechanically joined floorboards in a direction perpendicular to the surface plane, wherein all parts of the portions of the lower lip which are connected with the core, seen from the point where the surface plane and the joint plane intersect, are located outside a plane which is positioned further away from said point than a locking plane which is parallel therewith and which is tangent to the coacting locking surfaces of the tongue groove and the tongue where these are most inclined relative to the surface plane, wherein the coacting supporting surfaces of the lower lip and of the tongue, seen parallel with the surface plane, are positioned at a distance from, and closer to the joint plane than to the outer free end of the tongue, wherein all parts of the portions of the lower lip which are connected with the core are shorter than the upper lip and terminate at a distance from the joint plane, the lower lip is flexible, the upper lip is more rigid than the lower lip, and the upper and lower lips of the joint edge portions are formed to enable connection of a laid floorboard with said adjoining floorboard by a pushing-together motion essentially parallel with the surface plane of the laid floorboard for snapping together the parts of the locking system during downward bending of the lower lip of the tongue groove.

20d A plurality of aspects of the invention are also applicable to the known systems without these aspects being combined with the preferred locking systems described here.

The invention also describes the basic principles that should be satisfied for a tongue and groove joint which is to be snapped in with a minimum bending of joint i ~

components and wi.th the surface planes of the floorboards - on essentially th.e same level.
The invention also describes how material properties can be used to achieve high strength and 1ow cost in com-bi.nation with snapping.
Different aspects of the i.nvention will now be described in more detail with reference to the accom-panying drawings which show different embodiments of the invention. The parts of the inventive board that are equivalent to those of the prior-art board in Figs 1-2 have throughout been given th.e same reference numerals.
Brief Description of the Drawings Figs 1a-c show in three steps a downward angling method for mechanical joining of lon.g sides of floorboards accordzng to WO 9426999.
Fi.gs 2a-c show in three steps a snappin.g-in method for mechanical joining of short sides of floor-boards according to WO 9426999.
Figs 3a-b show a floorboard according to WO 9426999 seen from above and from below respectively.
Figs 4a-b show two different embodiments of floorboards according to WO 9966151.
Figs 5a-b show floorboards according to GB 1430423.
Figs 6a-b show mechanical locking systems for the long side or the short side of floorboards accord-i.ng to WO 9627721.
Figs 7a-b show a mechanical locking system according to JP 3169967.
Figs 8a-b show boards according to DE-A-1212275.
Figs 9a-b show a snap joi.nt according to WO 9747834.
Figs 10a-b show a snap join.t according to FR 2675174.
Figs lia-b schematically illustrate two para11e1 joint edge portions of a first preferred embodiment of a floorboard according to the present invention.
Figs 12a-c show snapping-in of a variant of the inven-tion.

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1-7 PCTh"E02100042 10-01-~003 ~---Figs 13a-c show a downward and upward angling method using the in.vention.
Fig. 14 shows snapping-in of a production-adapted variant of the.invention.
Fig. 15 shows this variant of the invention to illu-strate taking-up by upward angli.ng while using bending and compression in the joint material.
Figs 16a-c show examples of a floorboard accordin.g to the inven.tion.
Figs 17a-c show how the joint system should be designed to facilitate snapping-in.
Fig. 18 shows snapping-in in an angled position.
Fig. 19 shows locking of short side with snapping-in.
Figs 20a-b show snapping-in of the outer and inner cor-ner portion of the short side.
Fig 21 shows a joint system according to the inven-tion with a flexible ton.guee Figs 22a-e show in detail snapping-in of the outer cor-ner porti.on of the short side by using an embodiment of the invention.
Figs 23 a-e illustrate in detail snapping-in of the inner corner portion of the short side by using an embodiment of the invention.
Detailed. Description of Preferred Embodiments A first preferred embodiment of a floorboard 1, 11, which is provided with a mechanical locking system according to the inventi.on, will now be described with reference to Figs 11a and llbe To facilitate the under-standing, the joint system is shown schematically. Tt should be ernphasised that a better function can be achieved with other preferred embodiments that will be described below.
Figs 11a, llb show schematically a sect.ion through a joint between a long side edge portion 4a of a board 1 and an opposite long side edge portion 4b of another board 1 .

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The upper sides of the boards are essentially posi-- tioned in a common surface p.~~.ane HP and th.e upper parts of the joint edge portions 4a, 4b engage each other in a vertical joint plane VP. The mechan.ical locking system results in locking of the boards relative to each other in both the vertical direction D1 and the horizontal direction D2 which extends perpen.dicular to the joint plane VP. During the laying of a floor with juxtaposed rows of boards, one board (1'), however, can be di.splaced along the other board (1) in a direction D3 (see Fig. 19) along the joint plane VP. Such a displacement can be used, for instance, to provide locking-together of floor-boards that are positioned in the same row.
To provide joining of the two joint edge portions perpendicular to the vertical plane VP and parallel with the horizontal plane HP, the edges of the tloorboard have in a manner known per se a tongue groove 36 in one edge portion 4a of the floorboard inside the joint plane VP, and a tonggue 38 formed in the other joint edge portion 4b and projecting beyond the joint plane VP.
In this embodiment the board 1 has a core or core 30 of wood which supports a surface layer of wood 32 on its front side and a balancing layer 34 on its rear side. The board 1 is rectangular and has a second mechanical lock-ing system also on the two parallel short sides. In sorne embodiments, this second locki.ng system can have the same design as the locking system of the long sides, but the locking system on the short sides can also be of a diffe-rent design accordi.ng to the invention or be a previously known mechanical locking system.
As an illustrati.ve, non-limiting example, the floor-board can be of parquet type with a thickn.ess of 15 mm, a length of 2.4 m and a width of 0.2 m. The invention, however, can also be used for parquet squares or boards of a different size.
The core 30 can be of larnella type and consist of narrow wooden blocks of an inex.pensive kind of wood. The : i3 t) 0 9 ].i): P; il.t..n =^~.!`- Q~ _ i:;1cA 7 Ci,U=-;Lit.l~.llt,.V_~~~~~.

CA 02433487 2003-07-01 PCT~SE02 00042 , 'r-Ce EJ a ~:. .,mm~af.0o. p`...~ ~y~pgg 1 ' 1-6i14Y3 " 24 surf ace la.yer 32 may h.ave a thickness of 3-4 mm and con-- sist of a decorative kind of hardwood and be varnished.
The balancing layer 34 of the rear side may consist of a 2 mm veneer layer. In some cases, i.t may be advantageous to u.se different types of wood materials in different parts of the floorboard for optimal properties wi.thin th.e indi.vidual parts of the floorboard.
As mentioned above, the mechanical locking system accordi.ng to the invention comprises a tongue groove 36 in one joint edge portion 4a of the floorboard, and a tongue 38 on the opposite joint edge portion 4b of the floorboard.
The tongue groove 36 is defined by u.pper and lower lips 39, 40 and has the form of an undercut groove with an opening between the two lips 39, 40.
The different parts of the tongue groove 36 are best seen in Fig. 11b. The tongue groove is formed in the core or core 30 and ex.tends from the edge of the floorboard..
Above the tongue groove, there is an upper edge portion or joint edge surface 41 which extends up to the surface plane HP. Inside the opening of the tongue groove, there is an upper engaging or supporting surface 43 whzch in this case is parallel with the surface plane HP. This engaging or supporting surface passes into an inclined locking surfa.ce 43 which has a locking angle A to the horizontal plane HP. Inside the locking surfacef there is surface portion 46 which forms the upper boundary surface of the undercut portion 35 of the tongue groove. The tongue groove further has a bottom end 48 which extends down to the lower li.p 40. On the upper side of this lip there i.s an engaging or supporting surface 50. The outer end of the lower 1ip has a joint edge surface 52 which is posi.tioned at a distance from the join.t plane VP.
The shape of the tongue is also best seen in Fig. 11b. The tongue is made of the material of the core or core 30 and exten.ds beyond the joint plane VP when this joi.nt edge portion 4b is mechanically joined with ::[)(l: - [j . 1) 1 .~,(1 7 .:'i y }1c.~ - f _ i ) .:. r1 i-Iy^op>Ti:i~~~::i)l:'.f~
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the joint edge portion 4a of an adjoining floorboard. The joint edge porti.on 4b also has an upper edge portion or upper joint edge surface 61 which extends along the joint plane VP down to the root of the tongue 38. The upper 5 side of the root of the tongue has an upper engaging or supporting surface 64 which in this case extends to an inclined locking surface 65 of an upwardly directed por-tion 8 close to the tip of the tongue. The locking sur-face 65 passes into a guidi.ng surface portion 66 which 10 ends in an upper surface 67 of the upwardly directed portion 8 of the tongue. After the surface 67 follows a bevel which may serve as a guiding surface 68. Th.i.s extends to the tip 69 of the tongue. At the lower end of the tip 69 there is a further guiding surface 70 15 which extends obli.quely downwards to the lower edge of the tongue and an engaging or supporting surface 71. The supporti.ng surface 71 is intended to coact with the sup-porting surface 50 of the lower lip when two such floor-boards are mechanically joined, so that their upper sides 20 are posi.ti.oned in the same surface plane HP and meet at a joint plane VP directed perpendicular thereto, so that the upper jo.int edge surface 41, 61 of the boards engage each other. The tongue has a lower joi.nt edge surface 72 which extends to the underside.
25 In this embodiment there are separate engaging or supporting surface 43, 64 in the tongue groove and on the tongue, respectively, which in'the locked state engage each other and coact with the lower supporting surfaces 50, 71 on the lower lip and on the tongue, respectively, to provide the locking in the direction D1 perpendicu.lar to the surface plane HP. In other embodiments, which will be described below, use is made of the lockin.g surfaces 45, 65 both as locking surfaces for locking together in the direction D2 parallel with the surface plane HP and as supporting surfaces for counteracting movements in the direction Dl perpendi.cular to the surface plane. In the embodiment according to Figs 11a, 2b, the locking sur-~t}t}3- r_ie:lktx~'[: a,,.~ ~ , ,- ,, .
~~+~ .~r. =[,,~'Gr:t>rit:u ~Q i~' 1"- ,PC10L 'it:iz;,1 czc:;uni4~?.t^ ,~U1P~~!1~1}~J;rt4~.3! _'i kr!dc:d Zx.' ~ 1 - 1-2 3 " 26 faces 45, 65 and.the engaging surfaces 43, 64 coact as upper supporting surfaces in the system.
As is apparent from th.e drawing, the tongue 38 extends beyond the joint plane VP and has an upwardly directed portion 8 at its free outer end or tip 69. The tongue has also a locking surface 65 which is formed to coact with the inner locki.ng surface 45 in the tongue groove 36 of an adjoining floorboard when two such floor-boards are mechani.cally joined, so that their front sides are positioned in the same surface plane HP and meet at a joint plane VP directed perpendicular theretoa As is eva.dent from Fig. 11b, the tongue 38 has a surface portion 52 between the locking surface 51 and the joi.nt plane VP. When two floorboards are join.ed, the surface portion 52 engages the surface portion 45 of the upper lip 8. To faci.litate insertion of the tongue into the undercut groove by inward angling or snapping-in the tongue can, as sh.own in. Figs 11a, 11b, have a bevel 66 between the locki.ng surface 65 and the surface portion 57. Moreover, a bevel 68 can be positioned between the surface portion 57 and the tip 69 of the tongue. The bevel 66 may serve as a guiding part by having a 1.ower angle of inclination to the surface plane than the angle of inclination A of the locking surfaces 43, 51.
The support-ing surface 71 of the tongue is in this embodiment essent.iallyy parallel with the surface plane HP. The tongue has a bevel 70 between thi.s supporting surface and the tip 69 of the tongue.
According to the invention, the lower lip 40 has a supporting surface 50 for coaction with the corresponding supporting surface 71 on the tongue 36. In thi.s embodi-ment, this supporting surface is posits.on.ed at a distance from the inner part 47 of the un.dercut groove. G+Ihen two floorboards are joined with each other, there is engage-ment both between the supporting surfaces 50, 71 and between the engaging or supporting surface 43 of the upper lip 39 and the corresponding engaging or supporting t~~ryy 0J ` FT'a o ~ O-P
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C,A 02433487 2003-07-01 ~-~ 10-01-2003 ' 27 surface 64 of the tongue. In this way, locking of the boards in the direction DI perpendicular to the surface plane HP is obtained.
Preferably, at least the major part of the inner part 47 of the undercut groove, seen parallel with the surface plane HP, is located further away from the joint plane VP than is the outer end or tip 69 of the tongue 36. By this design, manufacture is simplified to a con-siderable extent, and di.splacement of one floorboard 30 relative to another along the joint plane is facili.tated.
Another important feature of a mechanical locking system accord.ing to the invention is that all parts of the portion.s of the lower lip 40 which are connected with the core 30, seen from the point C, where the surface plane HP and the joint plane VP intersect, are located outside a plane LP2. This plane is located further away from sai.d point C than a locking plane LP1. which is parallel with the plane LP2 and which is tangent to the coacting locking surfaces 45, 65 of the undercut groove 36 and the tongue 38, where these locking surfaces are most inclined relative to the surface plane HP. Owing to this design, the undercut groove can, as will be describ-ed in more detail below, be made by using large disk-shaped rotating cutti.ng tools for machining of the edge portions of the floorboards.
A further important feature is that the lower lip 40 is resilient and that it is shorter than the upper lip 39. This enables production of the undercut using large rotating cutting tools which can be set at a relatively high angle to the horizonta.l plane, so that the locking surface 65 can be made with a high locking angle A. The high locking angle significantly reduces the downward component that arises in connecti.on with tensile load.
This means that the joint system will have high strength although the lower lip is resilient and thus has a lima.t-ed capability of counteracting a downward component. This results in optimisation for obtaining a high locking :
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:. }~~`:' -CA`02433487,2003-07-01 ~~T/A71e fr/ 42 = 10-01-2003 force in combination with lower resistance to snapping-in. High resistance to snapping-i.n makes snapping-i.n diffa.cu.lt and increases the risk of damage to th.e joint edge portions of the floorboards. The inventor has found that most materials used in floorboard.s can be made suf-ficiently resilient by being formed with lips of a suit-able thickness a.nd length which can work in the preferred joint system and provi.de sufficien.t locking force.
Figs 12a-c show snapping-in of two floorboards by bending of the lor,ver lip 40. As is evident from Fig. 12b, snapping-.in takes place with a minimum bending of the lower lip and wi.th the surface planes of the floorboards on essentially the same level. Th.is reduces the risk of cracking.
Figs 13a-c show that the locking system according to Figs 12a-c can also be used for upward angling and down-ward angling in connection with taki.ng-up and laying. The upper and lower lips 39, 40 and the tongue 38 are formed to enable disconn.ection of two mechanically joined floorboards by one floorboard being pi.voted upwards rela-tive to the other about a pivoting centre close to the intersection C between the surface plane HP and the joint plane VP so that the tongue of this floorboard is pivoted out of the undercut groove of the other floorboard.
The snap joint according to the invention can be used on both long side and short side of the floorboards.
Fig. 14 and Fig. 15 show, however, a variant of the invention which is above all suited for snappi.ng along the short side of a floorboard which is made of a rela-tively hard material, such as a hard kind of wood or a hard fibreboard.
In this embodiment, the tongue groove is essential-ly deeper than is required to receive the tongue. As a result, a higher bendability of the lower lip 40 is obtained. Moreover, the locking system has a long tongue with a thick locki.ng element 8. The locking surfaces 45, .
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65 are also heavily inclined. The dashed line indicates - the snapping motion.
The design according to Figs 14 and 15 allow discon-nection by upward angling of one board and a slight down-ward bendi.ng of the lower lip 40 of the other board.
However, i.n other more preferred embodiments of the invention, no downward ben.ding of the lower lip is necessary when disconnecting the floorboards.
In the locked position, it is possible to displace the floorboards in the longitudinal directi.on of the joi.nt. As a result, disconnection of, for examp7.e, the short sides can take place b_y pulling out in the longi-tudinal direction of the joint after disconnection of the long sides by, for instance, upward angling.
To facilitate manufacture, inward angling, upward angling, snapping-in and displaceability in the locked position and to mi.nimise the risk of creaking, a11 sur-faces that are not operati.ve to form a joint with tight upper joint edges and the vertical and horizontal joint should be formed so as not to be in contact with each other in the locked position and preferably also during locking and unlocking. Thi.s allows manufacture without requiri.ng high tolerances in these joint portions and reduces the friction i.n lateral displacement along the 'j oint edge. Ex.amples of surfaces or parts of the j oint system that should not be in contact with each other in the locked position are 46-67, 48-69, 50-70 and 52-72.
The join.t svstem accordi.ng to the preferred embodi-ment may cons.ist of several combinations of materials.
The upper lip 39 can be made of a rigid and hard upper surface layer 32 and a softer lower part which is part of the core 30. The lower lip 40 can consist of the same softer upper part 30 and also a lower soft part 34 which can be another kind of wood. The directions of the fibres i.n the three kinds of wood may vary. This can be used to provide a joint system which utilises these material pro-perties. The locking element i.s therefore according to ,,.
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' 30 the invention positioned closer to the upper hard and - rig-i d part, which thus is -flexible and compressible to a limited extent only, while th.e snap function is formed in the softer lower and flexible part. It shou.ld be pointed that the joint system can also be made in a homogeneous floorboard.
Figs 16a-c illustrate an example of a floorboard according to the inventione This embodiment shows speci-fically that the joint system on long side and short side is differently designed. On the short side, the locki.ng system is optimised for snapping by means of a high lock-ing angle, deeD tongue groove and upper lip shorter than lower lip while at the same time the lockin.g surfaces have a low height to reduce the requirement for downward bendin.g. On the long side, the joint system has been adjusted for joinin.g/taking-up by angular motions.
Moreover, the joint system may consist of different materials and combinations of rnaterials 30a, 30b and 30c.
It is also possible to select di.fferent materials on long and short sides. For example, the groove part 36 of the short sides may consist of a harder and more flexible wood materi.al than, for ira.stance, the tongue part 38 which can be hard and rigid and have other properties than the core of the long side. On the short side with the tongue groove 36 it is possi.ble, for instance, to choose a kind of wood 30b which is m.ore flex.ible than the kind of wood 30c on the other short side where the tongue is formed. This is particularly convenient in parquet floors with a lamellar core where the upper and lower side consist of different kinds of wood and the core consists of glued blocks. This construction gives great possibili.ties of varying the composition of mate-rials to optimise functi.on, strength and production cost.
zt is also possible to vary th.e material along the length of a side. Thus, for instance the blocks that are i positioned between the two short sides can be of diffe-' rent kinds of wood or materials so that some can be . .
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POe - 10-0x-2003 -' 3 l selected with regard to their contributing suitable _ properties which improve laying, strength etc. Different properties can also be achieved with different orienta-tion of fibres on long side and short side, and also plastic materials can be used on the short sides and, for instance, on di.fferent parts of the long side. If the floorboard or parts of its core consa.st of e.g. plywood with several layers, these layers can be selected so that the upper lip, the tongue and the lower lip on both long side and short side can all have parts wi.th different composition of materials, orientation of fibres etc.
which may give different properties as regards strength, bendability, machinability etc.
Figs 17a-c show the basic principl.e of how the lower part of the tongue should be designed in relation to the lower li.p 40 so as to facilitate a horizontal snapping--in according to the invention in a join.t system with an undercut or locking groove 8 in a rigid upper lip 39 and with a flexible lower lip 40. In this embodiment, the upper lip 39 is significantly more rigi.d, amon.g other things ow3ng to the fact that it can be thicker or that it may consist of harder and more rigid materials. The lower li.p 40 can be thinn.er and softer and the essential bendingg will therefore, in connection with snapping-in, take place in the lower lip 40. Snapping-i.n can be signi-ficantly facilitated among other things by the maximum bending of the lower lip 40 being limited as far as pos-sible. Fig. 17a shows that the bendin.g of the lower lip 40 will increase to a maximum bending level Bl which is characterized in that the tongue 38 is inserted so far into the tongue groove 36 that the rounded guiding parts come into contact with each other. When the tongue 38 is inserted still more, the lower lip 40 will be bent back un.ti.l the snapping-in is terminated and th.e locking ele-ment 8 is fully inserted in its final position in the undercut 35. The lower and front part 49 of th.e tongue 38 should be designed so as not to bend down the lower li.p NIP . ~11i ~{~,~ _ ,i:=,i?iri;:i_ i r~G;;ua;c;nCe'<01':'._, T:x,dc:d 1'))= C?PL:.dOC

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~ ~~ ~1__~ Rate~~ C-'SER; PCT/SE02/00042 '(~~' ~: ~':V=~~s~~.~~." t~,~:~Ã;~.~a~'v~-~t 10_01-2003 40 whi.ch instead should be forced downward by the iower . supporting surface 50. This part 49 of the tongue should have a shape which either touches or goes clear of the maxi.mum bending level of the lower lip 40 when this lower lip 40 is bent along the outer part of the lower engaging surface 50 of the tongue 38. If the tongue 38 has a shape which in this position overlaps the 1.ower lip 40, indi-cated by the dashed line 49b, the bending B2 according to Fig. 17b can be significantly greater. This may result i.n high friction in connection with sn.apping-in and a risk of the joint being damaged. Fig. 17c shows that the maxi-mum bendin.g can be limited by the tongue groove 36 and the tongue 38 being designed so that there is a space S4 between th.e lower and outer part 49 of the tongue and the lower lip 40. The upper lip being made more rigid and, the lower lip more flexible reduces th.e risk of edge ri.sing on the upper side of the laid floor as the floor shrinks and swells depend.ing on the relati.ve humidity of th.e indoor air. The greater rigidi.ty of the upper lip in combinat.ion with the arrangement of the locking surfaces also makes it possible for the joint to take up great pulling-apart forces transversely of the joint. Also the bendi.ng away of the lower lip contributes to minimisi.ng the risk of edge rising.
Hori2ontal snapping-in is normally used in connec-tion wi.th snapping-in of the short side'after locking of the long side. When snapping-in the long side, it is also possible to snap the joint system accordin.g to the inven-tion with one board in a slightly upwardly angled posi-tion. This upwardly angled snap position is illustrated i.n Fig. 18. Only a smalZ degree of bend.i.ng B3 of the lower lip 40 is necessary for the gu.iding part 66 of the locking element to come into contact with the guiding part 44 of the locking groove so that the locking element can then by downward an.gling be inserted into the under-cut 35.

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F 'trCi vs Pa5'an4 ONt; 0 PCT/SE02/00042 Figs 19 and 20 also describe a problem which can arise in connection with snapping-in of two short sides of two boards 2a and 2b which are already joined on their long sides with another first board 1. When the floor-board 2a is to be joined with the floorboard 2b by snap acti.on, the inner corner portions 91 and 92, closest to the long side of the fi.rst board 1, are positioned in the same plane. This is due to the fact that the two boards 2a and 2b on their respective long sides are joined to the same floorboard 1. According to Fig. 20b, which shows the section C3-C4, the tongue 38 cannot be inserted into th.e tongue groove 39 to begin th.e downward bending of the lower lip 40. Tn the outer corner portions 93, 94 on the other long side, in the section C3-C4 shown in Fig. 20a, the tongue 38 can be inserted into the tongue groove 36 to begin the down.ward bending of the lower lip 40 by the board 2b being automatically pressed and angled upwards corresponding to the height of the locking element 8.
The inventor has thus discovered that there may be problems in connection with snapping-in of inner corner portions in lateral displacement in the same plane when the ton.gue is formed with an upwardly directed portion at its tip and is to be in.serted into a tongue groove wi.th an undercut. These problems may cause a high resistance to snapping-in and a ri.sk of cracking in the joint system. The problem can be solved=by a suitable join.t design and choice of materials which enabZe material deformation and bending in a plurality of joint portions.
When snapping-in such a specially designed joint system, the following takes place. Tn-lateral displace-ment, the outer guiding parts 42, 68 of the tongue and the upper 1.ip coact and force the upwardly directed porti.on or locking element 8 of the tongue under the outer part of the upper lip 39. The tongue bends downward and the upper lip bends upward. This is indicated by arrows in Fig. 20b. The corner portion 92 in Fig. 19 is pressed upward by the lower lip 40 on the long side of .-;0 1):i- q =--09 l_fj : ' ..7 V ;:pe^.a.Zilkt ' ~~~ ~ , z:m~ud'~ b ' C?4, L".L 7 C~.ccURic::' ,li: ~~~' = 1~~ Y . C~uG
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~`9~' ~t=^csr~'3`''.~ ~'D~,~ '','.; ~~'~=/'- ai'~.., PCTfSE02100042 < 10-01-2003 ' 34 the board 2b being bera.t and the corner portion 91 being pressed downward by the upper lip on the long side of the board 2a being bent upward. The joint system should be con.structed so that the sum of these four deformations is so great that the locking element can slide along the upper li.p and snap into the undercut 35. It is known that it should be possible for the tongue groove 36 to widen i.n connection with snapping-in. However, it is not known that it may be an advantage if the tongue, wh.ich normally should be ri.gid, should also be designed so as to be able to bend in connection with snappin.g-in.
Such an embodiment is shown in. Fig. 21. A groove or the like 63 is made at the upper and i.nner part of the tongue inside the vertical plane VP. The entire extent PB
of the tongue from its inner part to its outer part can be extended, and it can, for instance, be made greater than half the floor thickness T.
Figs 22 and 23 show how the parts of the joint sys-tem bend in connection with snapping-in at the inner corner portion. 91, 92 (Fig. 19) and the outer corner por-tion 93, 94 (Fig. 19) of two floorboards 2a and 2b. To simplify manufacture, it is required that only the thin lip and the tongue bend. In practice, of course all parts that are subjected to pressure will be cornpressed and bent to a varying degree depending on thickness, bendabi-lity, composition of materials etc.
Fig. 22a shows the outer corner portion 93, 94 and Fig. 23a shows the inner corner portion 91; 92. These two Figures show the positi.on when th.e edges of the boards come into contact with each other. The joint system is designed so that even in this position the outermost tip of the tongue 38 .is located inside the outer part of the lower 1ip 40. When the boards are pushed towards each other still more, the tongue 38 will in the inner corner 91, 92 press the board 2b upward according to Figs 22b, 23b. The tongue wi11 bend downward and the board 2b at the outer corner portion 93, 94 will be angled upward.
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Fig. 23c shows that the tongue 38 at the inner corn.er 91, 92 will be bent downward_ At the outer corner 93, 94 according to Fig. 22c, the tongue 38 is bent upward and the lower lip 40 downward. A.ccording to Figs 22d,, 23d, this bending continues as the boards are pushed towards each other still more and now also the lower lip 40 is bent at the inner corner 91, 92 according to Fig. 23d.
Figs 22d, 23e show the snapped-in position. Thus, snapping-i.n can be facilitated significantly if the tongue 38 is also flexible and if the outer part of the tongue 38 is positioned inside the outer part of the lower lip 40 when tongue and groove come into contact with each other when the boards are positioned in the same pla.ne in connection with snapping-in that takes place after locking of the floorboard along its two other sides.
Several variants can exist within the scope of the i.nvention. The inventor has rnanufactured and evaluated a large number of variants where the different parts of the joint system have been manufactured with different widths, lengths, thicknesses, angles and radii of a num-ber of different board materials and of homogeneous plas-tic and wooden panels. All joint systems have been tested in a position turned upside-down and with snapping and angling of groove and tongue boards relative to each other and wi.th different combinations of the systems here described and also prior-art systems on long side and short side. Locking syatems have been manufactured where locking surfaces are also upper engaging surfaces, where the tongue and groove have had a plurality of locking elements and locking grooves, and where also the lower lip and the lower part of the tongue have been formed with horizontal locka.ng means in the form of locking ele-ment and locking groove.

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Claims (62)

CLAIMS:

1. A flooring system comprising a plurality of identical floorboards, which are mechanically joinable at a joint plane, said floorboards having a core, a front side, a rear side and opposite joint edge portions, of which one is formed as a tongue groove, which is defined by upper and lower lips and has a bottom end, and the other is formed as a tongue with an upwardly directed portion at its free outer end, the tongue groove, seen from the joint plane, having the shape of an undercut groove with an opening, an inner portion and an inner locking surface, and at least parts of the lower lip being formed integrally with the core of the floorboard, and the tongue having a locking surface which is formed to coact with the inner locking surface in the tongue groove of an adjoining floorboard, when two such floorboards are mechanically joined, so that their front sides are positioned in the same surface plane and meet at the joint plane directed perpendicular thereto, wherein the inner locking surface of the tongue groove is formed on the upper lip within the undercut portion of the tongue groove for coaction with the corresponding locking surface of the tongue, said locking surface being formed on the upwardly directed portion of the tongue to counteract pulling-apart of two mechanically joined boards in a direction perpendicular to the joint plane, wherein the lower lip has a supporting surface for coaction with a corresponding supporting surface on the tongue, said supporting surfaces being intended to coact to counteract a relative displacement of two mechanically joined boards in a direction perpendicular to the surface plane, wherein all parts of the portions of the lower lip which are connected with the core, seen from the point where the surface plane and the joint plane intersect, are located outside a plane which is positioned further away from said point than a locking plane which is parallel therewith and which is tangent to the coacting locking surfaces of the tongue groove and the tongue where these are most inclined relative to the surface plane, wherein the coacting supporting surfaces of the lower lip and of the tongue, seen parallel with the surface plane, are positioned at a distance from, and closer to the joint plane than to the free outer end of the tongue, wherein all parts of the portions of the lower lip which are connected with the core are shorter than the upper lip and terminate at a distance from the joint plane, the lower lip is flexible, the upper lip is more rigid than the lower lip, and the upper and lower lips of the joint edge portions are formed to enable connection of a laid floorboard with a new floorboard by a pushing together motion essentially parallel with the surface plane of the laid floorboard for snapping together the parts of the locking system during downward bending of the lower lip of the tongue groove.

2. A flooring system as claimed in claim 1, wherein the tongue is flexible.

3. A flooring system as claimed in claim 1 or 2, wherein the joint edge portions are designed to enable connection of a laid floorboard with a new floorboard by a pushing-together motion with the surface plane of the floorboards essentially aligned with each other during bending of the tongue and the lower lip.

4. A flooring system as claimed in any one of claims 1 to 3, wherein the upper and lower lips of the joint edges are designed to enable disconnection of two mechanically joined floorboards by upward pivoting of one floorboard relative to the other about a pivoting centre close to a point of intersection between the surface plane and the joint plane for disconnecting the tongue of the one floorboard from the tongue groove of the other floorboard.

5. A flooring system as claimed in claim 4, wherein the upper and lower lips of the joint edges are designed to enable disconnection of two mechanically joined floorboards by upward pivoting of one floorboard relative to the other about a pivoting centre close to a point of intersection between the surface plane and the joint plane for disconnecting the tongue of one floorboard from the tongue groove of the other floorboard during downward bending of the lower lip.

6. A flooring system as claimed in any one of claims 1 to 5, wherein at least the major part of the bottom end of the tongue groove, seen parallel with the surface plane, is located further away from the joint plane than is the outer end of the tongue.

7. A flooring system as claimed in any one of claims 1 to 6, wherein the supporting surface of the tongue and the lower lip, which are designed for coaction, are set at a smaller angle to the surface plane than are the coacting locking surfaces of the upper lip and the tongue.

8. A flooring system as claimed in any one of claims 1 to 7, wherein the locking surfaces are set at essentially the same angle to the surface plane as a tangent to a circular arc, which is tangent to the locking surfaces engaging each other, at a point closest to the bottom of the undercut groove and which has its centre at the point where the surface plane and the joint plane intersect.

9. A flooring system as claimed in any one of claims 1 to 7, wherein the locking surfaces are set at greater angle to the surface plane than a tangent to a circular arc, which is tangent to the locking surfaces engaging each other at a point closest to the bottom of the undercut groove and which has its centre at the point where the surface plane and the joint plane intersect.

10. A flooring system as claimed in any one of claims 1 to 9, wherein the upper lip and the tongue have contact surfaces which in their locked state coact with each other and which are positioned within an area between the joint plane and the locking surfaces of the tongue and the upper lip, which locking surfaces in the locked state coact with each other.

11. A flooring system as claimed in claim 10, wherein the contact surfaces, seen from the coacting locking surfaces of the tongue and the upper lip, are inclined upwards and outwards to the joint plane.

12. A flooring system as claimed in claim 10, wherein the contact surfaces are essentially parallel with the surface plane.

13. A flooring system as claimed in any one of claims 10 to 12, wherein the contact surfaces are essentially plane.

14. A flooring system as claimed in any one of claims 1 to 13, wherein the undercut groove and the tongue are of such a design that the outer end of the tongue is positioned at a distance from the undercut groove along essentially the entire distance from the locking surfaces of the upper lip and the tongue, which locking surfaces engage each other, to the coacting supporting surfaces of the lower lip and the tongue.

15. A flooring system as claimed in claim 14, wherein a surface portion of the outer end of the tongue, which is in contact with a surface portion of the undercut groove has a smaller extent seen in the vertical plane than do the locking surfaces when two such boards are mechanically joined.

16. A flooring system as claimed in any one of claims 1 to 14, wherein the edge portions with their tongue and tongue groove, respectively, are designed so that, when two floorboards are joined, there is surface contact between the edge portions along at most 30% of the edge surface of the edge portion supporting the tongue, measured from the upper side of the floorboard to its underside.

17. A flooring system as claimed in any one of claims 1 to 16, wherein the coacting supporting surfaces of the tongue and the lower lip are set at an angle of at least 10° to the surface plane.

18. A flooring system as claimed in claim 17, wherein the coacting supporting surfaces of the tongue and the lower lip are set at an angle of at most 30° to the surface plane.

19. A flooring system as claimed in claim 18, wherein the coacting supporting surfaces of the tongue and the lower lip are set at an angle at most 20° to the surface plane.

20. A flooring system as claimed in any one of claims 1 to 19, wherein at least parts of the supporting surfaces of the lower lip and the tongue are positioned at a greater distance from the joint plane than are the inclined locking surfaces of the upper lip and the tongue.

21. A flooring system as claimed in any one of claims 1 to 20, wherein the undercut groove and the tongue are designed to enable a floorboard which is mechanically joined with a similar floorboard to be displaced in a direction along the joint plane.

22. A flooring system as claimed in any one of claims 1 to 21, wherein the tongue and the undercut groove are designed to enable disconnection of one board from another by pivoting one board relative to the other while maintaining contact between the boards at a point of the joint edge portions of the boards close to the intersection between the surface plane and the joint plane.

23. A flooring system as claimed in claim 22, wherein the tongue and the undercut groove are designed to enable disconnection of boards by pivoting one board relative to another while maintaining contact between the boards at a point of the joint edge portions of the boards close to the intersection between the surface plane and the joint plane without essential contact between the tongue side facing away from the surface plane and the lower lip.

24. A flooring system as claimed in any one of claims 1 to 23, wherein the distance between the locking plane and the plane parallel therewith, outside which all parts of the lower lip portions connected with the core are located, is at least 10% of the thickness of the floorboard.

25. A flooring system as claimed in any one of claims 1 to 24, wherein the locking surfaces of the upper lip and the tongue form an angle to the surface plane of below 90° but at least 20°.

26. A flooring system as claimed in claim 25, wherein locking surfaces of the upper lip and the tongue form an angle to the surface plane of at least 30°.

27. A flooring system as claimed in any one of claims 1 to 26, wherein the coacting supporting surfaces of the tongue and the lower lip are directed at an angle to the joint plane which is equal to or smaller than a tangent to a circular arc which is tangent to the supporting surfaces engaging each other at a point closest to the bottom of the undercut groove and which has its centre at the point where the surface plane and the joint plane intersect, seen in cross-section through the board.

28. A flooring system as claimed in claim 27, wherein the coacting supporting surfaces of the tongue and the lower lip are set at a greater angle to the surface plane than a tangent to a circular arc, which is tangent to the supporting surfaces engaging each other at a point closest to the bottom of the undercut groove and which has its centre at the point where the surface plane and the joint plane intersect.

29. A flooring system as claimed in any one of claims 1 to 28, wherein the supporting surfaces of the tongue and the lower lip, which are designed for coaction, are set at a smaller angle to the surface plane than are the coacting locking surfaces of the upper lip and the tongue.

30. A flooring system as claimed in claim 29, wherein the supporting surfaces of the tongue and the lower lip, which are designed for coaction, are inclined in the same direction as but at a smaller angle to the surface plane than are the coacting locking surfaces of the upper lip and the tongue.

31. A flooring system as claimed in any one of claims 27 to 30, wherein the supporting surfaces form an at least 20° greater angle to the surface plane than do the locking surfaces.

32. A flooring system as claimed in claim 31, wherein the supporting surfaces form an at least 20° greater angle to the surface plane than do the locking surfaces.

33. A flooring system as claimed in any one of claims 1 to 32, wherein the locking surfaces of the upper lip and the tongue are essentially plane within at least the surface portions which are intended to coact with each other when two such boards are joined.

34. A flooring system as claimed in claim 33, wherein the tongue has a guiding surface which is positioned outside the locking surface of the tongue, seen from the joint plane, and which has a smaller angle to the surface plane than does this locking surface.

35. A flooring system as claimed in any one of claims 1 to 34, wherein the upper lip has a guiding surface which is positioned closer to the opening of the tongue groove than is the locking surface of the upper lip and which has a smaller angle to the surface plane than does the locking surface of the upper lip.

36. A flooring system as claimed in any one of claims 1 to 35, wherein at least parts of the supporting surfaces of the lower lip and the tongue are positioned at a greater distance from the joint plane than are the inclined locking surfaces of the upper lip and the tongue.

37. A flooring system as claimed in any one of claims 1 to 36, wherein the locking surface of the tongue, is arranged at a distance of at least 0.1 times the thickness of the floorboard from the tip of the tongue.

38. A flooring system as claimed in any one of claims 1 to 37, wherein the vertical extent of the locking surfaces coacting with each other is smaller than half the vertical extent of the undercut, seen from the joint plane and parallel with the surface plane.

39. A flooring system as claimed in any one of claims 1 to 38, wherein the locking surfaces, seen in a vertical section through the floorboard, have an extent which is at most 10% of the thickness of the floorboard.

40. A flooring system as claimed in any one of claims 1 to 39, wherein the length of the tongue, seen perpendicular away from the joint plane, is at least 0.3 times the thickness of the board.

41. A flooring system as claimed in any one of claims 1 to 40, wherein the joint edge portion supporting the tongue and/or the joint edge portion supporting the tongue groove has/have a recess which is positioned above the tongue and terminates at a distance from the surface plane.

42. A flooring system as claimed in any one of claims 1 to 41, wherein the undercut groove, seen in the cross-section, has an outer opening portion which tapers inwards in the form of a funnel.

43. A flooring system as claimed in claim 42, wherein the upper lip has a bevel at its outer edge positioned furthest away from the surface plane.

44. A flooring system as claimed in any one of claims 1 to 43, wherein the tongue, seen in cross-section, has a tip that tapers.

45. A flooring system as claimed in any one of claims 1 to 44, wherein the tongue, seen in cross-section, has a split tip with an upper and a lower tongue part.

46. A flooring system as claimed in claim 45, wherein the upper and lower tongue parts of the tongue are made of different materials with different material properties.

47. A flooring system as claimed in any one of claims 1 to 46, wherein the tongue groove and the tongue are formed integrally with the floorboard.

48. A flooring system as claimed in any one of claims 1 to 47, wherein the upper lip is thicker than the lower lip.

49. A flooring system as claimed in any one of claims 1 to 48, wherein the minimum thickness of the upper lip adjacent to the undercut is greater than the maximum thickness of the lower lip adjacent to the supporting surface.

50. A flooring system as claimed in any one of claims 1 to 49, wherein the extent of the supporting surfaces is at most 150 of the thickness of the floorboard.

51. A flooring system as claimed in any one of claims 1 to 50, wherein the vertical extent of the tongue groove between the upper and the lower lip, measured parallel with the joint plane and at the outer end of the supporting surface, is at least 30% of the thickness of the floorboard.

52. A flooring system as claimed in any one of claims 1 to 51, wherein the depth of the tongue groove, measured from the joint plane, is at least 2% greater than the corresponding extent of the tongue.

53. A flooring system as claimed in any one of claims 1 to 52, wherein the tongue has other material properties than the upper or lower lip.

54. A flooring system as claimed in any one of claims 1 to 53, wherein the upper and lower lips are made of materials with different properties.

55. A flooring system as claimed in any one of claims 1 to 54, wherein the locking system also comprises a second mechanical lock, which is formed of a locking groove which is formed on the underside of the joint edge portion supporting the tongue and extends parallel with the joint plane, and a locking strip which is integrally attached to the joint edge portion of the board under the groove and extends along, essentially the entire length of the joint edge portion and has a locking component which projects from the strip and which, when two such boards are mechanically joined, is received in the locking groove of the adjoining board.

56. A flooring system as claimed in claim 55, wherein the locking strip projects beyond the joint plane.

57. A flooring system as claimed in any one of claims 1 to 56, wherein it is formed in a board which has a core of wood-fibre-based material.

58. A flooring system as claimed in claim 57, wherein it is formed in a board which has a core of wood.

59. A flooring system as claimed in any one of claims 1 to 58, wherein the floorboards are quadrilateral with sides which are parallel in pairs.

60. A flooring system as claimed in claim 59, wherein the floorboards have mechanical locking systems at all their four lateral edge portions.

61. A flooring system as claimed in claim 59 or 60, wherein the joint edge portion with the tongue and/or the joint edge portion with the tongue groove on one pair of parallel joint edge portions has/have been formed with other material properties than the joint edge portion with the tongue and/or the joint edge portion with the tongue groove on the other pair of parallel joint edge portions.

62. A floorboard for providing the flooring system as claimed in any one of claims 1 to 61, by mechanical joining of the floorboard with similar floorboards at a joint plane between said floorboard and said adjoining similar floorboard, said floorboard having a core, a front side, a rear side and opposite joint edge portions, of which one is formed as a tongue groove, which is defined by upper and lower lips and has a bottom end, and the other is formed as a tongue with an upwardly directed portion at its free outer end, the tongue groove, seen from the joint plane, having the shape of an undercut groove with an opening, an inner portion and an inner locking surface, and at least parts of the lower lip being formed integrally with the core of the floorboard, and the tongue having a locking surface which is formed to coact with the inner locking surface in the tongue groove of said adjoining floorboard so that their front sides are positioned in the same surface plane and meet at the joint plane directed perpendicular thereto, wherein the inner locking surface of the tongue groove is formed on the upper lip within the undercut portion of the tongue groove for coaction with the corresponding locking surface of the tongue, said locking surface being formed on the upwardly directed portion of the tongue to counteract pulling-apart of said two mechanically joined floorboards in a direction perpendicular to the joint plane, wherein the lower lip has a supporting surface for coaction with a corresponding supporting surface on the tongue, said supporting surfaces being intended to coact to counteract a relative displacement of said two mechanically joined floorboards in a direction perpendicular to the surface plane, wherein all parts of the portions of the lower lip which are connected with the core, seen from the point where the surface plane and the joint plane intersect, are located outside a plane which is positioned further away from said point than a locking plane which is parallel therewith and which is tangent to the coacting locking surfaces of the tongue groove and the tongue where these are most inclined relative to the surface plane, wherein the coacting supporting surfaces of the lower lip and of the tongue, seen parallel with the surface plane, are positioned at a distance from, and closer to the joint plane than to the outer free end of the tongue, wherein all parts of the portions of the lower lip which are connected with the core are shorter than the upper lip and terminate at a distance from the joint plane, the lower lip is flexible, the upper lip is more rigid than the lower lip, and the upper and lower lips of the joint edge portions are formed to enable connection of a laid floorboard with said adjoining floorboard by a pushing-together motion essentially parallel with the surface plane of the laid floorboard for snapping together the parts of the locking system during downward bending of the lower lip of the tongue groove.