Jointing system

In a system for jointing together of adjacent pieces of flooring material by means of grooves (3) and tongues (4), at least one of the opposing surfaces on the tongues (4) and the grooves (3) of the pieces display flocked surface portions (10-13). The flocked surface portions (10-13) extend along the tongues (4) and/or the grooves (3) and cover substantially their entire length. The fiber length (9) of the flocked surface portions (10-13) exceeds the difference between the width of the grooves (3) and the thickness of the tongues (4).

TECHNICAL FIELD 
The present invention relates to a system for tongue and groove jointing of 
adjacent pieces of flooring material. 
The present invention also relates to a flooring material which is composed 
of a number of smaller pieces provided with tongues and grooves. 
BACKGROUND ART 
Flooring materials of the parquet floor type are previously known in the 
art as displaying surface coatings of, for example, veneer, laminate or 
the like on the upper and lower sides. The flooring material is in the 
form of tiles or elongate, relatively narrow strips which, in the central 
region seen in the cross sectional direction, have a panel or core forming 
layer often of wood or wood-based materials such as core-board, hardboard, 
chipboard, MDF board (medium density fiber board) or the like. 
Along their edges, the pieces of such flooring material are provided with 
tongues and grooves (T&G) which are joined together when a floor is laid. 
In order to positionally fix the different pieces of the flooring 
material, glue is employed to a large extent, so that a large continuous 
sheet is formed of the flooring material which thereby covers a complete 
floor in one continuous unbroken piece or stratum. 
The use of glue for jointing together smaller pieces of flooring material 
is time-consuming and involves risks that the surface coating layers, 
principally on the upper side of the material, be dirtied so that they 
become unusable or at least require cleaning. 
PROBLEM STRUCTURE 
The present invention has for its object to devise the system intimated by 
way of introduction such that it obviates the drawbacks inherent in older, 
prior art designs and constructions. In particular, the present invention 
has for its object to realise a system which eliminates the need for glue 
in jointing together of T&G on adjacent pieces of flooring material. Thus, 
the present invention relates to a system which permits adjacent pieces of 
flooring material quite simply to be slid together in order thereafter to 
be separable from one another only with great difficulty or using force. 
Finally, the present invention has for its object to realise a system 
which is simple and economical to produce. 
SOLUTION 
The objects forming the basis of the present invention will be attained if 
the system intimated by way of introduction is characterized in that at 
least one of the opposing surfaces on the tongues and grooves of the 
flooring pieces are provided with flocked surface portions. 
The flocked surface portions display such length of individual fibers that 
these are bent on jointing together of two adjacent pieces of flooring 
material. The thus bent or curved fibers will hereby act as a very large 
number of barbs which must be bent or deformed in connection with the 
separation of the flooring material pieces from one another. Taken as a 
whole, these fibers generate extremely great cohesive forces. 
Further advantages will be attained if the present invention is also given 
one or more of the characterizing features as set forth in appended claims 
2 to 10.

DESCRIPTION OF PREFERRED EMBODIMENTS 
In FIG. 1, reference numerals 1 and 2 relate to two pieces of a flooring 
material in which a first piece 1 is provided with a groove 3 for jointing 
together with a corresponding tongue 4 on the other flooring piece 2. The 
different pieces of flooring material which, in daily parlance, are often 
called "laminated parquet", have upper surface coating layers 5 which, on 
the one hand, are intended to be of decorative appearance in order, for 
example, to imitate a "genuine" parquet floor and, on the other hand, 
possess good resistance to wear etc. Seen in the cross sectional direction 
centrally in the pieces 1 and 2, these have cores 6 or panel forming 
portions which preferably consist of wood or wood-based material. For 
example, the cores may consist of coreboard, plywood, hardboard, 
chipboard, MDF board (medium density fiber board) or similar material. 
Finally, the pieces 1 and 2 have, on their underside, a lower surface 
coating 7 whose function is to act as a barrier layer preventing the 
flooring material from warping as a result of damp, temperature 
differences or other factors. Thus, the purpose of the barrier layer 7 is 
to keep the pieces of flooring material in a planar state. As far as the 
flooring material and the pieces thereof are described above, they are to 
be considered as conventional 
In its most general form, the present invention implies that at least one 
of the counter-facing surfaces on the tongues 4 and grooves 3 of the 
pieces 1 and 2 are provided with a large number of barb devices. These 
barb devices are designed in such a manner that, on jointing together of 
tongue and groove, they are folded or bent obliquely backwards in the 
direction of insertion of the tongue 4 into the groove 3 in order to 
engage with an opposing surface on the other material piece (FIG. 6). In 
order to be able to separate the material pieces 1 and 2 from one another, 
i.e. by withdrawing the tongue 4 from the groove 3, it is necessary that 
these barb devices be considerably deformed, substantially in their own 
longitudinal direction, or that they be forced into the opposing surface 
on the other material piece. If the barb devices are present in large 
numbers, extremely great forces may occur which prevent withdrawal of the 
tongue 4. 
In one practical embodiment, the barb devices are formed from so-called 
flocks which are applied according to the foregoing and which extend in 
the longitudinal direction of the tongues and/or the grooves and cover 
substantially the whole of their length. 
A flock consists of a base 8 (FIG. 6) in the form of a layer or foil of 
suitable adhesive or binder in which the one end of a very large number of 
approximately equal-length fibers 9 (FIG. 6) are secured. The individual 
fibers are straight and at least transversely directed, but preferably 
approximately at right angles to the plane of the base and the subjacent 
surface. 
The application of the base 8 may be effected by spraying, brushing or the 
like of a binder of suitable viscosity. Thereafter, the electrostatically 
charged short fiber pieces are blown or sprayed against the binder layer 
so that the ends of the individual fibers adhere in the base. As a result 
of the electrostatic charging with the same polarity on all fibers, the 
fibers will repel one another and assume a position such that they will be 
approximately at right angles to the substrate. 
It will further be apparent from FIG. 6 that the fiber length, or at least 
the average fiber length, exceeds the difference between the width of the 
grooves and the thickness of the tongues. This ensures the above-mentioned 
bending and oblique positioning of the fibers 9 on insertion of the tongue 
4 in the groove 3. 
In order to improve the capability of the barb devices or individual fibres 
9 to engage with the opposing surface, this is provided with a roughened, 
raised or uneven surface structure. If the core 6 in the pieces 1 and 2 
consists of wood or wood-based material, a suitable surface structure may 
be achieved by direct machine processing of this material. A suitable 
surface structure will thus be created by sawing, milling or grinding 
direct in the material of the core 6. 
In the embodiment according to FIG. 1, there is provided an elongate, strip 
shaped flock 10 on the upper side of the tongue 4. The flock 10 extends 
suitably along the tongue 4 preferably throughout its entire length. 
Furthermore, it is appropriate that the flock 10 covers as great a portion 
of the width of the tongue as possible. 
The application of the flock 10 to the tongue 4 is particularly simple, 
since the upper and lower surfaces of the tongue 4 are freely accessible 
for the electrostatic application of the fibers 9. 
FIG. 2 shows a relatively similar embodiment in which, however, the tongue 
4 is provided with flocks 10 and 11 on its upper and lower sides, 
respectively. 
In the embodiment according to FIG. 2, the tongue 4 may suitably be of 
slightly lesser thickness in relation to the width of the groove 3 than 
was the case in the embodiment according to FIG. 1. 
In FIG. 3, use is made of a flock 10 on the upper side of the tongue 4 and 
a flock 12 on the lower defining surface of the groove 3. In this 
embodiment, the fit between the tongue and the groove should correspond to 
that which applied in the embodiment according to FIG. 2. 
FIG. 4 shows an embodiment in which the tongue 4 is provided with a flock 
10 and in which, in addition, the groove 3 is provided with flocks 12 and 
13 on its underside and upper side, respectively. The fit between the 
tongue and groove may possibly be slightly looser than was the case in the 
embodiment according to FIG. 3. 
FIG. 5 shows an embodiment in which the upper and lower sides of the tongue 
4 are provided with flocks 10 and 11. Correspondingly, the groove 3 also 
has flocks 12 and 13 on the under and upper sides, respectively. 
As an alternative to applying the base 8 direct to the defining surfaces of 
the tongue 4 or the groove 3, it may be appropriate to apply the base to a 
self-adhesive foil or carrier which is provided with the flock fiber. The 
self-adhesive carrier may then be clipped or cut to suitable strips which 
are applied to the intended surfaces on the tongue or groove. This 
embodiment would appear to be particularly advantageous in the application 
of the flocks 12 and 13 interiorly in the groove 3. 
The present invention may be further modified without departing from the 
spirit and scope of the appended claims.