U.S. patent application number 11/034059 was filed with the patent office on 2005-08-04 for floor covering and locking systems.
This patent application is currently assigned to Valinge Aluminium AB. Invention is credited to Pervan, Darko.
Application Number | 20050166516 11/034059 |
Document ID | / |
Family ID | 34811811 |
Filed Date | 2005-08-04 |
United States Patent
Application |
20050166516 |
Kind Code |
A1 |
Pervan, Darko |
August 4, 2005 |
Floor covering and locking systems
Abstract
Floorboards with a mechanical locking system that allows
movement between the floorboards when they are joined to form a
floating floor.
Inventors: |
Pervan, Darko; (Viken,
SE) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
Valinge Aluminium AB
Viken
SE
|
Family ID: |
34811811 |
Appl. No.: |
11/034059 |
Filed: |
January 13, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60537891 |
Jan 22, 2004 |
|
|
|
Current U.S.
Class: |
52/589.1 |
Current CPC
Class: |
B27F 1/02 20130101; E04F
2201/0153 20130101; E04F 15/02 20130101; E04F 15/02038 20130101;
B27F 1/08 20130101 |
Class at
Publication: |
052/589.1 |
International
Class: |
E04F 015/22 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 13, 2004 |
SE |
0400068-3 |
Claims
1. A semi-floating floor comprises rectangular floorboards joined
with a mechanical locking system and in which locking system the
joined floorboards have a horizontal plane which is parallel to a
floor surface and a vertical plane which is perpendicular to the
horizontal plane, said locking system having mechanically
cooperating locks for vertical joining parallel to the vertical
plane and for horizontal joining parallel to the horizontal plane
of a first and a second joint edge and in which locking system a
vertical lock comprising a tongue which cooperates with a tongue
groove and the horizontal lock comprising a locking element with a
locking surface which cooperates with a locking groove, wherein the
format, installation pattern and locking system of the floorboards
are designed in such a manner that a floor surface of 1*1 meter can
change in length .DELTA.TL in at least one direction at least 1 mm
when the floorboards are subjected to a compressive and a tensile
load in the horizontal plane, and that this change in length
.DELTA.TL can occur without visible joint gaps.
2. The semi-floating floor as claimed in claim 1, wherein the width
of the floorboards does not exceed about 120 mm.
3. The semi-floating floor as claimed in claim 2, wherein there is
an average play in the locking system of at least about 0.1 mm when
the boards are subjected to a compressive and a tensile load in the
horizontal plane.
4. The semi-floating floor as claimed in claim 3, wherein the
floorboards are joined long side against short side.
5. The semi-floating floor as claimed in claim 3, wherein the
floorboards have a surface layer of laminate, and that parts of the
surface layer on at least one joint edge have been removed.
6. The semi-floating floor as claimed in claim 3, wherein a surface
layer is laminate or wood veneer, the core of the floorboard is a
wood based board, the change in floor length .DELTA.TL is at least
1.0 mm when a force F of 100 kg/m of the joint edge is used, the
change in floor length .DELTA.TL is at least 1.5 mm when a force F
of 200 kg/m of the joint edge is used, the average joint gaps do
not exceed 0.15 mm when the force F is 100 kg/m of joint edge and
they do not exceed 0.20 mm when the force F is 200 kg/m of joint
edge.
7. The semi-flooring floor as claimed in claim 6, wherein the wood
based board is MDF or HDF.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority of Swedish Patent
Application No. 0400068-3, filed in Sweden on Jan. 13, 2004 and
U.S. Provisional Application No. 60/537,891, filed in the United
States on Jan. 22, 2004, the entire contents of which are hereby
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates generally to the technical field of
locking systems for floorboards. The invention concerns on the one
hand a locking system for floorboards which can be joined
mechanically and, on the other hand, floorboards and floor systems
provided with such a locking system and a production method to
produce such floorboards.
[0003] The present invention is particularly suited for use in
floating wooden floors and laminate floors, such as massive wooden
floors, parquet floors, floors with a surface of veneer, laminate
floors with a surface layer of high pressure laminate or direct
laminate and the like.
[0004] The following description of prior-art technique, problems
of known systems as well as objects and features of the invention
will therefore as non-limiting examples be aimed mainly at this
field of application. However, it should be emphasized that the
invention can be used in any floorboards, which are intended to be
joined in different patterns by means of a mechanical locking
system. The invention may thus also be applicable to floors which
are glued or nailed to the sub floor or floors with a core and with
a surface of plastic, linoleum, cork, varnished fiberboard surface
and the like.
DEFINITION OF SOME TERMS
[0005] In the following text, the visible surface of the installed
floorboard is called "front side", while the opposite side of the
floorboard facing the subfloor is called "rear side". By "floor
surface" is meant the major outer flat part of the floorboard,
which is opposite to the rear side and which is located in one
single plane. Bevels, grooves and similar decorative features are
parts of the front side but they are not parts of the floor
surface. By "laminate floor" is meant a floor having a surface,
which consists of melamine impregnated paper, which has been
compressed under pressure and heat. "Horizontal plane" relates to a
plane, which is extended parallel to the outer part of the floor
surface. "Vertical plane" relates to a plane perpendicular to the
horizontal plane.
[0006] The outer parts of the floorboard at the edge of the
floorboard between the front side and the rear side are called
"joint edge". By "joint edge portion" is meant a part of the joint
edge of the floorboard. By "joint" or "locking system" are meant
cooperating connecting means, which interconnect the floorboards
vertically and/or horizontally. By "mechanical locking system" is
meant that joining can take place without glue. Mechanical locking
systems can in many cases also be joined by glue. By "vertical
locking" is meant locking parallel to the vertical plane. As a
rule, vertical locking consists of a tongue, which cooperates with
a tongue groove. By "horizontal locking" is meant locking parallel
to the horizontal plane. By "joint opening" is meant a groove which
is defined by two joint edges of two joined floorboards and which
is open to the front side. By "joint gap" is meant the minimum
distance between two joint edge portions of two joined floorboards
within an area, which is defined by the front side and the upper
part of the tongue next to the front side. By "open joint gap" is
meant a joint gap, which is open towards the front side. By
"visible joint gap" is meant a joint gap, which is visible to the
naked eye from the front side for a person walking on the floor, or
a joint gap, which is larger than the general requirements on joint
gaps established by the industry for various floor types. With
"continuous floating floor surface" is meant a floor surface, which
is installed in one piece without expansion joints.
BACKGROUND OF THE INVENTION
[0007] Traditional laminate and parquet floors are usually
installed floating on an existing subfloor. The joint edges of the
floorboards are joined to form a floor surface, and the entire
floor surface can move relative to the subfloor. As the floorboards
shrink or swell in connection with the relative humidity RH varying
during the year, the entire floor surface will change in shape.
[0008] Floating floors of this kind are usually joined by means of
glued tongue and groove joints. In laying, the boards are brought
together horizontally, a projecting tongue along the joint edge of
one board being inserted into a tongue groove along the joint edge
of an adjoining board. The tongue and groove joint positions and
locks the floorboards vertically and the glue locks the boards
horizontally. The same method is used on both long side and short
side, and the boards are usually laid in parallel rows long side
against long side and short side against short side.
[0009] In addition to such traditional floating floors, which are
joined by means of glued tongue and groove joints, floorboards have
been developed in recent years, which do not require the use of
glue but which are instead joined mechanically by means of
so-called mechanical locking systems. These systems comprise
locking means, which lock the boards mechanically horizontally and
vertically without glue. The vertical locking means are generally
formed as a tongue, which cooperates with a tongue grove. The
horizontal locking means comprising a locking element, which
cooperates with a locking groove. The locking element could be
formed on a strip extending from the lower part of the tongue
groove or it could be formed on the tongue. The mechanical locking
systems can be formed by machining the core of the board.
Alternatively, parts of the locking system such as the tongue
and/or the strip can be made of a separate material, which is
integrated with the floorboard, i.e., already joined with the
floorboard in connection with the manufacture thereof at the
factory.
[0010] The floorboards can be joined mechanically by various
combinations of angling, snapping-in, vertical change of position
such as the so-called vertical folding and insertion along the
joint edge. All of these installation methods, except vertical
folding, require that one side of the floorboard, the long or short
side, could be displaced in locked position. A lot of locking
systems on the market are produced with a small play between the
locking element and the locking grove in order to facilitate
displacement. The intention is to produce floorboards, which are
possible to displace, and which at the same time are connected to
each other with a fit, which is as tight as possible. A very small
displacement play of for instance 0.01-0.05 mm is often sufficient
to reduce the friction between wood fibers considerably. According
to The European Standard EN 13329 for laminate floorings joint
openings between floorboards should be on an average .ltoreq.0.15
mm and the maximum level in a floor should be .ltoreq.0.20 mm. The
aim of all producers of floating floors is to reduce the joint
openings as much as possible. Some floors are even produced with a
pre-tension where the strip with the locking element in locked
position is bended backwards towards the sub floor and where the
locking element and the locking groove press the panels tightly
against each other. Such a floor is difficult to install.
[0011] Wooden and laminate floors are also joined by gluing or
nailing to the subfloor. Such gluing/nailing counteracts movements
due to moisture and keeps the floorboards joined. The movement of
the floorboards occurs about a center in each floorboard. Swelling
and shrinking can occur by merely the respective floorboards, and
thus not the entire floor surface, changing in shape.
[0012] Floorboards that are joined by gluing/nailing to the
subfloor do not require any locking systems at all. However, they
can have traditional tongue and groove joints, which facilitate
vertical positioning. They can also have mechanical locking
systems, which lock and position the floorboards vertically and/or
horizontally in connection with laying.
RELATED ART
[0013] The advantage of floating flooring is that a change in shape
due to different degrees of relative humidity RH can occur
concealed under baseboards and the floorboards can, although they
swell and shrink, be joined without visible joint gaps.
Installation can, especially by using mechanical locking systems,
take place quickly and easily and the floor can be taken up and be
laid once more in a different place. The drawback is that the
continuous floor surface must as a rule be limited even in the
cases where the floor consists of relatively dimensionally stable
floorboards, such as laminate floor with a fiberboard core or
wooden floors composed of several layers with different fiber
directions. The reason is that such dimensionally stable floors as
a rule have a change in dimension, which is about 0.1%
corresponding to about 1 mm per meter when the RH varies between
25% in winter and 85% in summer. Such a floor will, for example,
over a distance of ten meters shrink and swell about 10 mm. A large
floor surface must be divided into smaller surfaces with expansion
strips, for example, every tenth or fifteenth meter. Without such a
division, it is a risk that the floor when shrinking will change in
shape so that it will no longer be covered by baseboards. Also the
load on the locking system will be great since great loads must be
transferred when a large continuous surface is moving. The load
will be particularly great in passages between different rooms.
[0014] According to the code of practice established by the
European Producers of Laminate Flooring (EPLF), expansion joint
profiles should be installed on surfaces greater than 12 m in the
direction of the length of the individual flooring planks and on
surfaces greater than 8 m in the width direction. Such profiles
should also be installed in doorways between rooms. Similar
installation guidelines are used by producers of floating floors
with a surface of wood. Expansion joint profiles are generally
aluminum or plastic section fixed on the floor surface between two
separate floor units. They collect dirt, give an unwanted
appearance and are rather expensive. Due to these limitations on
maximum floor surfaces, laminate floorings have only reached a
small market share in commercial applications such as hotels,
airports, and large shopping areas.
[0015] Unstable floors, such as homogenous wooden floors, may
exhibit still greater changes in shape. The factors that above all
affect the change in shape of homogenous wooden floors are fiber
direction and kind of wood. A homogenous oak floor is very stable
along the fiber direction, i.e., in the longitudinal direction of
the floorboard. In the transverse direction, the movement can be 3%
corresponding to 30 mm per meter or more as the RH varies during
the year. Other kinds of wood exhibit still greater changes in
shape. Floorboards exhibiting great changes in shape can as a rule
not be installed floating. Even if such an installation would be
possible, the continuous floor surface must be restricted
significantly.
[0016] The advantage of gluing/nailing to the subfloor is that
large continuous floor surfaces can be provided without expansion
joint profiles and the floor can take up great loads. A further
advantage is that the floorboards do not require any vertical and
horizontal locking systems, and they can be installed in advanced
patterns with, for example, long sides joined to short sides. This
method of installation involving attachment to the subfloor has,
however, a number of considerable drawbacks. The main drawback is
that as the floorboards shrink, a visible joint gap arises between
the boards. The joint gap can be relatively large, especially when
the floorboards are made of moisture sensitive wood materials.
Homogenous wooden floors that are nailed to a subfloor can have
joint gaps of 3-5 mm. The distance between the boards can be
irregularly distributed with several small and some large gaps, and
these gaps are not always parallel. Thus, the joint gap can vary
over the length of the floorboard. The large joint gaps contain a
great deal of dirt, which penetrates down to the tongue and
prevents the floorboards from taking their original position in
swelling. The installation methods are time-consuming, and in many
cases the subfloor must be adjusted to allow gluing/nailing to the
subfloor.
[0017] It would therefore be a great advantage if it were possible
to provide a floating floor without the above drawbacks, in
particular a floating floor which
[0018] a) May comprise a large continuous surface without expansion
joint profiles,
[0019] b) May comprise moisture sensitive floorboards, which
exhibit great dimensional changes as the RH varies during the
year.
SUMMARY
[0020] The present invention relates to locking systems,
floorboards and floors which make it possible to install floating
floors in large continuous surfaces and with floorboards that
exhibit great dimensional changes as the relative humidity (RH)
changes. The invention also relates to production methods and
production equipment to produce such floors.
[0021] A first object of the present invention is to provide a
floating floor of rectangular floorboards with mechanical locking
systems, in which floor the size, pattern of laying and locking
system of the floorboards cooperate and allow movements between the
floorboards. According to an embodiment of the invention, the
individual floorboards can change in shape after installation,
i.e., shrink and swell due to changes in the relative humidity.
This can occur in such a manner that the change in shape of the
entire floor surface can be reduced or preferably be eliminated
while at the same time the floorboards remain locked to each other
without large visible joint gaps.
[0022] A second object is to provide locking systems, which allow a
considerable movement between floorboards without large and deep
dirt-collecting joint gaps and/or where open joint gaps could be
excluded. Such locking systems are particularly suited for moisture
sensitive materials, such as wood, but also when large floating
floors are installed using wide and/or long floorboards.
[0023] The terms long side and short side are used in the
description to facilitate understanding. The boards can according
to the invention also be square or alternately square and
rectangular, and optionally also exhibit different patterns and
angles between opposite sides.
[0024] It should be particularly emphasized that the combinations
of floorboards, locking systems and laying patterns that appear in
this description are only examples of suitable embodiments. A large
number of alternatives are conceivable. All the embodiments that
are suitable for the first object of the invention can be combined
with the embodiments that describe the second object of the
invention. All locking systems can be used separately in long sides
and/or short sides and also in various combinations on long sides
and short sides. The locking systems having horizontal and vertical
locking means can be joined by angling and/or snapping-in. The
geometries of the locking systems and the active horizontal and
vertical locking means can be formed by machining the edges of the
floorboard or by separate materials being formed or alternatively
machined before or after joining to the joint edge portion of the
floorboard.
[0025] According to a first embodiment, a floating floor comprises
rectangular floorboards, which are joined by a mechanical locking
system. The joined floorboards have a horizontal plane, which is
parallel to the floor surface, and a vertical plane, which is
perpendicular to the horizontal plane. The locking system has
mechanically cooperating locks for vertical joining parallel to the
vertical plane and for horizontal joining parallel to the
horizontal plane of a first and a second joint edge. The vertical
locks comprise a tongue, which cooperates with a groove, and the
horizontal locks comprise a locking element with a locking surface
cooperating with a locking groove. The format, installation pattern
and locking system of the floorboards are designed in such a manner
that a floor surface of 1*1 meter can change in shape in at least
one direction at least 1 mm when the floorboards are pressed
together or pulled apart. This change in shape can occur without
visible joint gaps.
[0026] According to a second embodiment, a locking system is
provided for mechanical joining of floorboards, in which locking
system the joined floorboards have a horizontal plane which is
parallel to the floor surface and a vertical plane which is
perpendicular to the horizontal plane. The locking system has
mechanically cooperating locks for vertical joining parallel to the
vertical plane and for horizontal joining parallel to the
horizontal plane of a first and a second joint edge. The vertical
locks comprise a tongue, which cooperates with a groove and the
horizontal of a locking element with a locking surface, which
cooperates with a locking groove. The first and the second joint
edge have upper and lower joint edge portions located between the
tongue and the floor surface. The upper joint edge portions are
closer to the floor surface than the lower. When the floorboards
are joined and pressed against each other, the two upper joint edge
portions are spaced from each other and one of the upper joint edge
portions in the first joint edge overlaps a lower joint edge
portion in the second joint edge.
[0027] According to several preferred embodiments of this
invention, it is an advantage if the floor comprises rather small
floorboards and many joints, which could compensate swelling and
shrinking. The production tolerances should be rather small since
well-defined plays and joint openings are generally required to
produce a high quality floor according to the invention.
[0028] Small floorboards are however difficult to produce with the
required tolerance since they have a tendency to turn in an
uncontrolled manner during machining. The main reason why small
floorboards are more difficult to produce than large floorboards is
that large floorboard has a much large area, which is in contact
with a chain and a belt during the machining of the edges of the
floorboards. This large contact area keeps the floorboards fixed by
the belt to the chain in such a way that they cannot move or turn
in relation to the feeding direction, which may be the case when
the contact area is small.
[0029] Production of floorboards is essentially carried out in such
manner that a set of tools and a floorboard blank are displaced
relative to each other. A set of tools comprises preferably one or
more milling tools which are arranged and dimensioned to machine a
locking system in a manner known to those skilled in the art.
[0030] The most used equipment is an end tenor, double or single,
where a chain and a belt are used to move the floorboard with great
accuracy along a well defined feeding direction. Pressure shoes and
support unites are used in many applications together with the
chain and the belt mainly to prevent vertical deviations.
Horizontal deviation of the floorboard is only prevented by the
chain and the belt.
[0031] The problem is that in many applications this is not
sufficient, especially when panels are small.
[0032] A third object of the present invention is to provide
equipment and production methods which make it possible to produce
floorboards and mechanical locking systems with an end tenor but
with better precision than what is possible to accomplish with
known technology.
[0033] Equipment for production of building panels, especially
floorboards, comprises a chain, a belt, a pressure shoe and a tool
set. The chain and the belt are arranged to displace the floorboard
relative the tool set and the pressure shoe, in a feeding
direction. The pressure shoe is arranged to press towards the rear
side of the floorboard. The tool set is arranged to form an edge
portion of the floorboard when the floorboard is displaced relative
the tool set. One of the tools of the tool set forms a guiding
surface in the floorboard. The pressure shoe has a guiding device,
which cooperates with the guiding surface and prevents deviations
in a direction perpendicular to the feeding direction and parallel
to the rear side of the floorboard.
[0034] It is known that a grove could be formed on the rear side of
a floorboard and that a ruler could be inserted into the groove to
guide the floorboards when they are displaced by a belt that moves
the boards on a table. It is not known that special guiding
surfaces and guiding devices could be used in an end tenor where a
pressure shoe cooperates with a chain.
[0035] A fourth object of the present invention is to provide a
large semi-floating floor of rectangular floorboards with
mechanical locking systems, in which floor the format, installation
pattern and locking system of the floorboards are designed in such
a manner that a large semi-floating continuous surface, with length
or width exceeding 12 m, could be installed without expansion
joints.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIGS. 1a-1b show floorboards with locking system.
[0037] FIGS. 2a-2f show locking systems and laying patterns.
[0038] FIGS. 3a-3e show locking systems.
[0039] FIGS. 4a-4c show locking systems.
[0040] FIGS. 5a-5d show joined floorboards and testing methods.
[0041] FIGS. 6a-6e show locking systems.
[0042] FIGS. 7a-7e show locking systems.
[0043] FIGS. 8a-8f show locking systems.
[0044] FIGS. 9a-9d show locking systems.
[0045] FIGS. 10a-10d show production equipment
[0046] FIGS. 11a-11d show production equipment
[0047] FIGS. 12a-12c show locking system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0048] FIGS. 1a and 1b illustrate floorboards which are of a first
type A and a second type B according to the invention and whose
long sides 4a and 4b in this embodiment have a length which is 3
times the length of the short sides 5a, 5b. The long sides 4a, 4b
of the floorboards have vertical and horizontal connectors, and the
short sides 5a, 5b of the floorboards have horizontal connectors.
In this embodiment, the two types are identical except that the
location of the locks is mirror-inverted. The locks allow joining
of long side 4a to long side 4b by at least inward angling and long
side 4a to short side 5a by inward angling, and also short side 5b
to long side 4b by a vertical motion. Joining of both long sides
4a, 4b and short sides 5a, 5b in a herringbone pattern or in
parallel rows can in this embodiment take place merely by an
angular motion along the long sides 4a, 4b. The long sides 4a, 4b
of the floorboards have connectors, which in this embodiment
comprising a strip 6, a tongue groove 9 and a tongue 10. The short
sides 5a also have a strip 6 and a tongue groove 9 whereas the
short sides 5b have no tongue 10. There may be a plurality of
variants. The two types of floorboards need not be of the same
format and the locking means can also have different shapes,
provided that as stated above they can be joined long side against
short side. The connectors can be made of the same material, or of
different materials, or be made of the same material but with
different material properties. For instance, the connectors can be
made of plastic or metal. They can also be made of the same
material as the floorboard, but be subjected to a treatment
modifying their properties, such as impregnation or the like. The
short sides 5b can have a tongue and the floorboards can then be
joined in prior-art manner in a diamond pattern by different
combinations of angular motion and snap motions. Short sides could
also have a separate flexible tongue, which during locking could be
displaced horizontally.
[0049] FIG. 2a shows the connectors of two floorboards 1, 1' that
are joined to each other. In this embodiment, the floorboards have
a surface layer 31 of laminate, a core 30 of, for instance, HDF,
which is softer and more compressible than the surface layer 31,
and a balancing layer 32. The vertical locking D1 comprises a
tongue groove 9, which cooperates with a tongue 10. The horizontal
locking D2 comprises a strip 6 with a locking element 8, which
cooperates with a locking groove 12. This locking system can be
joined by inward angling along upper joint edges. It could also be
modified in such a way that it could be locked by horizontal
snapping. The locking element 8 and the locking groove 12 have
cooperating locking surfaces 15, 14. The floorboards can, when
joined and pressed against each other in the horizontal direction
D2, assume a position where there is a play 20 between the locking
surfaces 14, 15. FIG. 2b show that when the floorboards are pulled
apart in the opposite direction, and when the locking surfaces 14,
15 are in complete contact and pressed against each other, a joint
gap 21 arises in the front side between the upper joint edges. The
play between the locking surfaces 14, 15 are defined as equal to
the displacement of the upper joint edges when these edges are
pressed together and pulled apart as described above. This play in
the locking system is the maximum floor movement that takes place
when the floorboards are pressed together and pulled apart with a
pressure and pulling force adapted to the strength of the edge
portions and the locking system. Floorboards with hard surface
layers or edges, which when pressed together are only compressed
marginally, will according to this definition have a play, which is
essentially equal or slightly larger than the join gap. Floorboards
with softer edges will have a play which is considerable larger
than the joint gap. According to this definition, the play is
always larger or equal to the joint gap. The play and joint gap can
be, for example, 0.05-0.10 mm. Joint gaps, which are about 0.1 mm,
are considered acceptable. They are difficult to see and normal
dirt particles are too big to penetrate into the locking system
through such small joint gaps. In some applications joint gaps up
to 0.20 mm, with a play of for example 0.25 mm could be accepted,
especially if play and joint gaps are measured when a considerable
pressure and pulling force is used. This maximum joint gap will
occur in extreme conditions only when the humidity is very low, for
example below 20% and when the load on the floor is very high. In
normal condition and applications the joint gap in such a floor
could be 0.10 mm or less.
[0050] FIG. 2b shows an ordinary laminate floor with floorboards in
the size of 1.2*0.2 m, which are installed in parallel rows. Such a
laminate floor shrinks and swells about 1 mm per meter. If the
locking system has a play of about 0.1 mm, the five joints in the
transverse direction D2 B will allow swelling and shrinking of
5*0.1=0.5 mm per meter. This compensates for only half the maximum
swelling or shrinking of 1 mm. In the longitudinal direction D2 A,
there is only one joint per 1.2 m, which allows a movement of 0.1
mm. The play 20 and the joint gap 21 in the locking system thus
contribute only marginally to reduce shrinking and swelling of the
floor in the direction D2 parallel to the long sides. To reduce the
movement of the floor to half of the movement that usually occurs
in a floor without play 20 and joint gap 21, it is necessary to
increase the play 20 to 0.6 mm, and this results in too big a joint
gap 21 on the short side.
[0051] FIG. 2c shows floorboards with, for instance, a core 30 of
fiberboard, such as HDF, and a surface layer of laminate or veneer,
which has a maximum dimensional change of about 0.1%, i.e., 1 mm
per meter. The floorboards are installed in parallel rows. In this
embodiment, they are narrow and short with a size of, for example,
0.5*0.08 m. If the play is 0.1 mm, 12 floorboards with their 12
joints over a floor length of one meter will allow a movement in
the transverse direction D2 B of 1.2 mm, which is more than the
maximum dimensional change of the floor. Thus the entire movement
may occur by the floorboards moving relative to each other, and the
outer dimensions of the floor can be unchanged. In the longitudinal
direction D2 A, the two short side joints can only compensate for a
movement of 0.2 mm per meter. In a room which is, for example, 10 m
wide and 40 m long, installation can suitably occur, contrary to
the present recommended installation principles, with the long
sides of the floorboards parallel to the width direction of the
room and perpendicular to the length direction thereof. According
to this preferred embodiment, a large continuous floating floor
surface without large visible joint gaps can thus be provided with
narrow floorboards which have a locking system with play and which
are joined in parallel rows perpendicular to the length direction
of the floor surface. The locking system, the floorboards and the
installation pattern should thus be adjusted so that a floor
surface of 1*1 m can expand and be pressed together about 1 mm or
more in at least one direction without damaging the locking system
or the floorboards. A mechanical locking system in a floating floor
which is installed in home settings should have a mechanical
locking system that withstands tensile load and compression
corresponding to at least 200 kg per meter of floor length. More
specifically, it should preferably be possible to achieve the above
change in shape without visible joint gaps when the floor surface
above is subjected to a compressive or tensile load of 200 kg in
any direction and when the floorboards are conditioned in normal
relative humidity of about 45%.
[0052] The strength of a mechanical locking system is of great
importance in large continuous floating floor surfaces. Such large
continuous surfaces are defined as a floor surface with length
and/or width exceeding 12 m. Very large continuous surfaces are
defined as floor surfaces with length and/or width exceeding 20 m.
There is a risk that unacceptable joint gaps will occur or that the
floorboards will slide apart, if the mechanical locking system is
not sufficiently strong in a large floating floor. Dimensionally
stable floorboards, such as laminate floors, which show average
joint gaps exceeding 0.2 mm, when a tensile load of 200 kg/m is
applied, are generally not suitable to use in a large high quality
floating floor. The invention could be used to install continuous
floating floors with a length and/or width exceeding 20 m or even
40 m. In principle there are no limitations. Continuous floating
floors with a surface of 10,000 m.sup.2 or more could be installed
according to invention.
[0053] Such new types of floating floors where the major part of
the floating movement, in at least one direction, takes place
between the floorboards and in the mechanical locking system are
hereafter referred to as Semi-floating Floors.
[0054] FIG. 5d illustrates a suitable testing method in order to
ensure that the floorboards are sufficiently mobile in the joined
state and that the locking system is strong enough to be used in a
large continuous floating floor surface where the floor is a Semi
Floating Floor. In this example, 9 samples with 10 joints and with
a length L of 100 mm (10% of 1 meter) have been joined along their
respective long sides so as to correspond to a floor length TL of
about 1 meter. The amount of joints, in this example, 10 joints, is
referred to as Nj. The boards are subjected to compressive and
tensile load using a force F corresponding to 20 kg (200 N), which
is 10% of 200 kg. The change in length of the floor length TL,
hereafter referred to as .DELTA.TL, should be measured. The average
play, hereafter referred to as AP or floor movement per joint is
defined as AP=.DELTA.TL/Nj. If for example .DELTA.TL=1.5 mm, than
the average play AP=1.5/10=0.15 mm. This testing method will also
measure dimensional changes of the floorboard. Such dimensional
changes are in most floorboards extremely small compared to the
play. As mentioned before, due to compression of top edges and
eventually some very small dimensional changes of the floor board
itself, the average joint gap will always be smaller than the
average play AP. This means that in order to make sure that the
floor movement is sufficient (.DELTA.TL) and that the average joint
gaps 21 do not exceed the stipulated maximum levels, only .DELTA.TL
has to be measured and controlled, since .DELTA.TL/Nj is always
larger or equal to the average joint gap 21. The size of the actual
average joint gap 21 in the floor, when the tensile force F is
applied, could however be measured directly for example with a set
of thickness gauges or a microscope and the actual average joint
gap=AAJG could be calculated. The difference between AP and MJG is
defined as floorboard flexibility=FF (FF=AP-AAJG). In a laminate
floor .DELTA.TL should preferably exceed 1 mm. Lower or higher
force F could be used to design floorboards, installation patterns
and locking systems which could be used as Semi Floating Floors. In
some applications for example in home environment with normal
moisture conditions a force F of 100 kg (1000 N) per meter could be
sufficient. In very large floating floors a force F of 250-300 kg
or more could be used. Mechanical locking systems could be designed
with a locking force of 1000 kg or more. The joint gap in such
locking systems could be limited to 0.2 mm even when a force F of
400-500 kg is applied. The pushback effect caused by the locking
element 8, the locking surfaces 15, 14 and the locking strip 6
could be measured by increasing and decreasing the force F in steps
of for example 100 kg. The pushback effect is high If .DELTA.TL is
essentially the same when F is increased from 0 to 100 kg
(=.DELTA.TL1) as when F is increased from 0 to 200 kg and than
decreased back to 100 kg (=.DELTA.TL2). A mechanical locking system
with a high pushback effect is an advantage in a semi-floating
floor. Preferably .DELTA.TL1 should be at least 75% of .DELTA.TL2.
In some applications even 50% could be sufficient.
[0055] FIG. 2d shows floorboards according to FIG. 2c which are
installed in a diamond pattern. This method of installation results
in 7 joints per running meter in both directions D2 A and D2 B of
the floor. A play of 0.14 mm can then completely eliminate a
swelling and shrinking of 0.1% since 7 joints result in a total
mobility of 7*0.14=1.0 mm.
[0056] FIG. 2e shows floor surface of one square meter which
consists of the above-described floorboards installed in a
herringbone pattern long side against short side and shows the
position of the floorboards when, for instance, in summer they have
swelled to their maximum dimension. FIG. 2f shows the position of
the floorboards when, for instance, in winter, they have shrunk.
The locking system with the inherent play then results in a joint
gap 21 between all joint edges of the floorboards. Since the
floorboards are installed in a herringbone pattern, the play of the
long sides will help to reduce the dimensional changes of the floor
in all directions. FIG. 2f also shows that the critical direction
is the diagonal directions D2 C and D2 D of the floor where 7 joint
gaps must be adjusted so as to withstand a shrinkage over a
distance of 1.4 m. This can be used to determine the optimal
direction of laying in a large floor. In this example, a joint gap
of 0.2 mm will completely eliminate the movement of the floor in
all directions. This allows the outer portions of a floating floor
to be attached to the subfloor, for example, by gluing, which
prevents the floor, when shrinking, to be moved outside the
baseboards. The invention also allows partition walls to be
attached to an installed floating floor, which can reduce the
installation time.
[0057] Practical experiments demonstrate that a floor with a
surface of veneer or laminate and with a core of a fiberboard-based
panel, for instance a dimensionally stable high quality HDF, can be
manufactured so as to be highly dimensionally stable and have a
maximum dimensional change in home settings of about 0.5-1.0 mm per
meter. Such semi-floating floors can be installed in spaces of
unlimited size, and the maximum play can be limited to about 0.1 mm
also in the cases where the floorboards have a width of preferably
about 120 mm. It goes without saying that still smaller
floorboards, for instance 0.4*0.06 m, are still more favorable and
can manage large surfaces also when they are made of materials that
are less stable in shape. According to a first embodiment, a new
type of semi-floating floor where the individual floorboards are
capable of moving and where the outer dimensions of the floor need
not be changed. This can be achieved by optimal utilization of the
size of the boards, the mobility of the locking system using a
small play and a small joint gap, and the installation pattern of
the floorboards. A suitable combination of play, joint gap, size of
the floorboard, installation pattern and direction of laying of the
floorboards can thus be used in order to wholly or partly eliminate
movements in a floating floor. Much larger continuous floating
floors can be installed than is possible today, and the maximum
movement of the floor can be reduced to the about 10 mm that apply
to current technology, or be completely eliminated. All this can
occur with a joint gap which in practice is not visible and which
is not different, regarding moisture and dirt penetration, from
traditional 0.2 m wide floating floorboards which are joined in
parallel rows by pretension or with a very small displacement play
which does not give sufficient mobility. As a non-limiting example,
it can be mentioned that the play 20 and the joint gap 21 in
dimensionally stable floors should preferably be about 0.1-0.2
mm.
[0058] An especially preferred embodiment according to the
invention is a semi-floating floor with the following
characteristics: The surface layer is laminate or wood veneer, the
core of the floorboard is a wood based board such as MDF or HDF,
the change in floor length .DELTA.TL is at least 1,0 mm when a
force F of 100 kg/m is used, the change in floor length .DELTA.TL
is at least 1.5 mm when a force F of 200 kg/m is used, average
joint gaps do not exceed 0.15 mm when the force F is 100 kg/m and
they do not exceed 0.20 mm when the force F is 200 kg/m.
[0059] The function and joint quality of such semi-floating
floorboards will be similar to traditional floating floorboards
when humidity conditions are normal and the size of the floor
surface is within the generally recommended limits. In extreme
climate conditions or when installed in a much larger continuous
floor surface, such semi-floating floorboard will be superior to
the traditional floorboards. Other combinations of force F, change
in floor length .DELTA.TL and joint gap 21 could be used in order
to design a semi-floating floor for various application.
[0060] FIG. 3a shows a second embodiment, which can be used to
counteract the problems caused by movements due to moisture in
floating floors. In this embodiment, the floorboard has a surface
31 of direct laminate and a core of HDF. Under the laminate
surface, there is a layer 33, which consists of melamine
impregnated wood fibers. This layer forms, when the surface layer
is laminated to HDF and when melamine penetrates into the core and
joins the surface layer to the HDF core. The HDF core 30 is softer
and more compressible than the laminate surface 31 and the melamine
layer 33. According to the invention, the surface layer 31 of
laminate and, where appropriate, also parts of, or the entire,
melamine layer 33 under the surface layer can be removed so that a
decorative groove 133 forms in the shape of a shallow joint opening
JO 1. This joint opening resembles a large joint gap in homogeneous
wooden floors. The groove 133 can be made on one joint edge only,
and it can be colored, coated or impregnated in such a manner that
the joint gap becomes less visible. Such decorative grooves or
joint openings can have, for example, a width JO 1 of, for example,
1-3 mm and a depth of 0.2-0.5 mm. In some application the width of
JO 1 could preferably be rather small about 0.5-1.0 mm When the
floorboards 1, 1' are pressed towards each other, the upper joint
edges 16, 17 can be compressed. Such compression can be 0.1 mm in
HDF. Such a possibility of compression can replace the
above-mentioned play and can allow a movement without a joint gap.
Chemical processing as mentioned above can also change the
properties of the joint edge portion and help to improve the
possibilities of compression. Of course, the first and second
embodiment can be combined. With a play of 0.1 mm and a possibility
of compression of 0.1 mm, a total movement of 0.2 mm can be
provided with a visible joint gap of 0.1 mm only. Compression can
also be used between the active locking surfaces 15, 14 in the
locking element 8 and in the locking groove 12. In normal climatic
conditions the separation of the floorboards is prevented when the
locking surfaces 14, 15 are in contact with each other and no
substantial compression occurs. When subjected to additional
tensile load in extreme climatic conditions, for instance when the
RH falls below 25%, the locking surfaces will be compressed. This
compression is facilitated if the contact surface CS of the locking
surfaces 14, 15 are small. It is advantageous if this contact
surface CS in normal floor thicknesses 8-15 mm is about 1 mm or
less. With this technique, floorboards can be manufactured with a
play and joint gap of about 0.1 mm. In extreme climatic conditions,
when the RH falls below 25% and exceeds 80%, compression of upper
joint edges and locking surfaces can allow a movement of for
instance 0.3 mm. The above technique can be applied to many
different types of floors, for instance floors with a surface of
high pressure laminate, wood, veneer and plastic and like
materials. The technique is particularly suitable in floorboards
where it is possible to increase the compression of the upper joint
edges by removing part of the upper joint edge portion 16 and/or
17.
[0061] FIG. 3b illustrates a third embodiment. FIGS. 3c and 3d are
enlargements of the joint edges in FIG. 3b. The floorboard 1' has,
in an area in the joint edge which is defined by the upper parts of
the tongue 10 and the groove 9 and the floor surface 31, an upper
joint edge portion 18 and a lower joint edge portion 17, and the
floorboard 1 has in a corresponding area an upper joint edge
portion 19 and a lower joint edge portion 16. When the floorboards
1, 1' are pressed together, the lower joint edge portions 16, 17
will come into contact with each other. This is shown in FIG. 3d.
The upper joint edge portions 18, 19 are spaced from each other,
and one upper joint edge portion 18 of one floorboard 1' overlaps
the lower joint edge portion 16 of the other floorboard 1. In this
pressed-together position, the locking system has a play 20 of for
instance 0.2 mm between the locking surfaces 14, 15. If the overlap
in this pressed-together position is 0.2 mm, the boards can, when
being pulled apart, separate from each other 0.2 mm without a
visible joint gap being seen from the surface. This embodiment will
not have an open joint gap because the joint gap will be covered by
the overlapping joint edge portion 18. This is shown in FIG. 3c. It
is an advantage if the locking element 8 and the locking grove 12
are such that the possible separation i.e. e. the play is slightly
smaller then the overlapping. Preferably a small overlapping, for
example 0.05 mm should exist in the joint even when the floorboards
are pulled apart and a pulling force F is applied to the joint.
This overlapping will prevent moisture to penetrate into the joint.
The joint edges will be stronger since the lower edge portion 16
will support the upper edge portion 18. The decorative groove 133
can be made very shallow and all dirt collecting in the groove can
easily be removed by a vacuum cleaner in connection with normal
cleaning. No dirt or moisture can penetrate into the locking system
and down to the tongue 12. This technique involving overlapping
joint edge portions can, of course, be combined with the two other
embodiments on the same side or on long and short sides. The long
side could for instance have a locking system according to the
first embodiment and the short side according to the second. For
example, the visible and open joint gap can be 0.1 mm, the
compression 0.1 mm and the overlap 0.1 mm. The floorboards'
possibility of moving will then be 0.3 mm all together and this
considerable movement can be combined with a small visible open
joint gap and a limited horizontal extent of the overlapping joint
edge portion 18 that does not have to constitute a weakening of the
joint edge. This is due to the fact that the overlapping joint edge
portion 18 is very small and also made in the strongest part of the
floorboard, which consists of the laminate surface, and melamine
impregnated wood fibers. Such a locking system, which thus can
provide a considerable possibility of movement without visible
joint gaps, can be used in all the applications described above.
Furthermore the locking system is especially suitable for use in
broad floorboards, on the short sides, when the floorboards are
installed in parallel rows and the like, i.e., in all the
applications that require great mobility in the locking system to
counteract the dimensional change of the floor. It can also be used
in the short sides of floorboards, which constitute a frame FR, or
frieze round a floor installed in a herringbone pattern according
to FIG. 5c. In this embodiment, shown in FIGS. 3b-3d, the vertical
extent of the overlapping joint edge portion, i.e., the depth GD of
the joint opening, is less than 0.1 times the floor thickness T. An
especially preferred embodiment according to the invention is a
semi-floating floor with the following characteristics: The surface
layer is laminate or wood veneer, the core of the floorboard is a
wood based board such as MDF or HDF, the floor thickness T is 6-9
mm and the overlapping OL is smaller than the average play AP when
a force F of 100 kg/m is used. As an example it could be mentioned
that the depth GD of the joint opening could be 0.2-0.5 mm
(=0.02*T-0.08 T). The overlapping OL could be 0.1-0.3 mm
(=0.01*T-0.05*T) on long sides. The overlapping OL on the short
sides could be equal or larger than the overlapping on the long
sides.
[0062] FIG. 3e show an embodiment where the joint opening JO 1 is
very small or nonexistent when the floorboards are pressed
together. When the floorboards are pulled apart, a joint opening JO
1 will occur. This joint opening will be substantially of the same
size as the average play AP. The decorative groove could for
example be colored in some suitable design matching the floor
surface and a play will not cause an open joint gap. A very small
overlapping OL of some 0.1 mm (0.01*T-0.02*T) only and slightly
smaller average play AP could give sufficient floor movement and
this could be combined with a moisture resistant high quality
joint. The play will also facilitate locking, unlocking and
displacement in locked position. Such overlapping edge portions
could be used in all known mechanical locking systems in order to
improve the function of the mechanical locking system.
[0063] FIGS. 4a and 4b show how a locking system can be designed so
as to allow a floating installation of floor-boards, which comprise
a moisture sensitive material. In this embodiment, the floorboard
is made of homogeneous wood.
[0064] FIG. 4a shows the locking system in a state subjected to
tensile load, and FIG. 4b shows the locking system in the
compressed state. For the floor to have an attractive appearance,
the relative size of the joint openings should not differ much from
each other. To ensure that the visible joint openings do not differ
much while the floor moves, the smallest joint opening JO 2 should
be greater than half the greatest joint opening JO 1. Moreover, the
depth GD should preferably be less than 0.5*TT, TT being the
distance between the floor surface and the upper parts of the
tongue/groove. In the case where there is no tongue, GD should be
less than 0.2 times the floor thickness T. This facilitates
cleaning of the joint opening. It is also advantageous if JO 1 is
about 1-5 mm, which corresponds to normal gaps in homogeneous
wooden floors. According to the invention, the overlapping joint
edge portion should preferably lie close to the floor surface. This
allows a shallow joint opening while at the same time vertical
locking can occur using a tongue 10 and a groove 9 which are placed
essentially in the central parts of the floorboard between the
front side and the rear side where the core 30 has good stability.
An alternative way of providing a shallow joint opening, which
allows movement, is illustrated in FIG. 4c. The upper part of the
tongue 10 has been moved up towards the floor surface. The drawback
of this solution is that the upper joint edge portion 18 above the
tongue 10 will be far too weak. The joint edge portion 18 can
easily crack or be deformed.
[0065] FIGS. 5a and 5b illustrate the long side joint of three
floorboards 1, 1' and 1" with the width W. FIG. 5a shows the
floorboards where the RH is low, and FIG. 5b shows them when the RH
is high. To resemble homogeneous floors, broad floorboards should
preferably have wider joint gaps than narrow ones. JO 2 should
suitably be at least about 1% of the floor width W. 100 mm wide
floorboards will then have a smallest joint opening of at least 1
mm. Corresponding joint openings in, for example, 200 mm wide
planks should be at least 2 mm. Other combinations can, of course,
also be used especially in wooden floors where special requirements
are made by different kinds of wood and different climatic
conditions.
[0066] FIG. 6a shows a wooden floor, which consists of several
layers of wood. The floorboard may comprise, for example, an upper
layer of high-grade wood, such as oak, which constitutes the
decorative surface layer 31. The core 30 may comprise, for example,
plywood, which is made up of other kinds of wood or by
corresponding kinds of wood but of a different quality.
Alternatively the core may comprise or wood lamellae. The upper
layer 31 has as a rule a different fiber direction than a lower
layer. In this embodiment, the overlapping joint edges 18 and 19
are made in the upper layer. The advantage is that the visible
joint opening JO 1 will comprise the same kind of wood and fiber
direction as the surface layer 31 and the appearance will be
identical with that of a homogeneous wooden floor.
[0067] FIGS. 6b and 6c illustrate an embodiment where there is a
small play 22 between the overlapping joint edge portions 16, 18,
which facilitate horizontal movement in the locking system. FIG. 6c
shows joining by an angular motion and with the upper joint edge
portions 18, 19 in contact with each other. The play 20 between the
locking surface 15 of the locking element 8 and the locking groove
12 significantly facilitates joining by inward angling, especially
in wooden floors that are not always straight.
[0068] In the above-preferred embodiments, the overlapping joint
portion 18 is made in the tongue side, i.e., in the joint edge
having a tongue 10. This overlapping joint portion 18 can also be
made in the groove side, i.e., in the joint edge having a groove 9.
FIGS. 6d and 6e illustrate such an embodiment. In FIG. 6d, the
boards are pressed together in their inner position, and in FIG. 6e
they are pulled out to their outer position.
[0069] FIGS. 7a-7b illustrate that it is advantageous if the upper
joint edge 18, which overlaps the lower 16, is located on the
tongue side 4a. The groove side 4b can then be joined by a vertical
motion to a side 4a, which has no tongue, according to FIG. 7b.
Such a locking system is especially suitable on the short side.
FIG. 7c shows such a locking system in the joined and
pressed-together state. FIGS. 7d and 7e illustrate how the
horizontal locks, for instance in the form of a strip 6 and a
locking element 8 and also an upper and lower joint portion 19, 16,
can be made by merely one tool TO which has a horizontally
operating tool shaft HT and which thus can form the entire joint
edge. Such a tool can be mounted, for example, on a circular saw,
and a high quality joint system can be made by means of a guide
bar. The tool can also saw off the floorboard 1. In the preferred
embodiment, only a partial dividing of the floorboard 1 is made at
the outer portion 24 of the strip 6. The final dividing is made by
the floorboard being broken off. This reduces the risk of the tool
TO being damaged by contacting a subfloor of, for instance,
concrete. This technique can be used to produce a frame or freize
FR in a floor, which, for instance, is installed in a herringbone
pattern according to FIG. 5c. The tool can also be used to
manufacture a locking system of a traditional type without
overlapping joint edge portions.
[0070] FIGS. 8a-8f illustrate different embodiments. FIGS. 8a-8c
illustrate how the invention can be used in locking systems where
the horizontal lock comprises a tongue 10 with a locking element 8
which cooperates with a locking groove 12 made in a groove 9 which
is defined by an upper lip 23 and where the locking groove 12 is
positioned in the upper lip 23. The groove also has a lower lip 24
which can be removed to allow joining by a vertical motion. FIG. 8d
shows a locking system with a separate strip 6, which is made, for
instance, of aluminum sheet. FIG. 8e illustrates a locking system
that has a separate strip 6 which can be made of a fiberboard-based
material or of plastic, metal and like materials.
[0071] FIG. 8f shows a locking system, which can be joined by
horizontal snap action. The tongue 10 has a groove 9' which allows
its upper and lower part with the locking elements 8, 8' to bend
towards each other in connection with horizontally displacement of
the joint edges 4a and 4b towards each other. In this embodiment,
the upper and lower lip 23, 24 in the groove 9 need not be
resilient. Of course, the invention can also be used in
conventional snap systems where the lips 23, 24 can be
resilient.
[0072] FIGS. 9a-9d illustrate alternative embodiments of the
invention. When the boards are pulled apart, separation of the
cooperating locking surfaces 14 and 15 is prevented. When boards
are pressed together, several alternative parts in the locking
system can be used to define the inner position. In FIG. 9a, the
inner position of the outer part of the locking element 8 and the
locking groove 10 is determined. According to FIG. 9b, the outer
part of the tongue 10 and the groove 9 cooperate. According to FIG.
9c the front and lower part of the tongue 10 cooperates with the
groove 9. According to FIG. 9d, a locking element 10' on the lower
part of the tongue 10 cooperates with a locking element 9' on the
strip 6. It is obvious that several other parts in the locking
system can be used according to these principles in order to define
the inner position of the floorboards.
[0073] FIG. 10a shows production equipments and production methods
according to the invention. The end tenor ET has a chain 40 and a
belt 41 which displace the floorboard 1 in a feeding direction FD
relative a tool set, which in this embodiment has five tools
51,52,53,54 and 55 and pressure shoes 42. The end tenor could also
have two chins and two belts. FIG. 10b is an enlargement of the
first tooling station. The first tool 51 in the tool set makes a
guiding surface 12 which in this embodiment is a groove and which
is mainly formed as the locking groove 12 of the locking system. Of
course other groves could be formed preferably in that part of the
floorboard where the mechanical locking system will be formed. The
pressure shoe 42' has a guiding device 43'which cooperates with the
groove 12 and prevents deviations from the feeding direction FD and
in a plane parallel to the horizontal plane. FIG. 10c shows the end
tenor seen from the feeding direction when the floorboard has
passed the first tool 51. In this embodiment the locking groove 12
is used as a guiding surface for the guiding device 43, which is
attached to the pressing shoe 42. The FIG. 10d shows that the same
groove 12 could be used as a guiding surface in all tool stations.
FIG. 10d shows how the tongue could be formed with a tool 54. The
machining of a particular part of the floorboard 1 can take place
when this part, at the same time, is guided by the guiding device
43. FIG. 11a shows another embodiment where the guiding device is
attached inside the pressure shoe. The disadvantage is that the
board will have a grove in the rear side. FIG. 11 b shows another
embodiment where one or both outer edges of the floorboard are used
as a guiding surface for the guiding device 43, 43'. The end tenor
has in this embodiment support units 44, 44' which cooperate with
the pressure shoes 42,42'. The guiding device could alternatively
be attached to this support units 44,44'. FIG. 11c and 11d shows
how a floorboard could be produced in two steps. The tongue side 10
is formed in step one. The same guiding groove 12 is used in step 2
(FIG. 11d) when the groove side 9 is formed. Such an end tenor will
be very flexible. The advantage is that floorboards of different
widths, smaller or larger than the chain width, could be
produced.
[0074] FIGS. 12a-12c show a preferred embodiment which guaranties
that a semi-floating floor will be installed in the normal position
which preferably is a position where the actual joint gap is about
50% of the maximum joint gap. If for instance all floorboards are
installed with edges 16, 17 in contact, problems may occur around
the walls when the floorboards swell to their maximum size. The
locking element and the locking groove could be formed in such a
way that the floorboards are automatically guided in the optimal
position during installation. FIG. 12c shows that the locking
element 8 in this embodiment has a locking surface with a high
locking angle LA close to 90 degree to the horizontal plane. This
locking angle LA is higher than the angle of the tangent line TL to
the circle C, which has a center at the upper joint edges. FIG. 12b
shows that such a joint geometry will during angling push the
floorboard 4a towards the floorboard 4b and bring it into the
above-mentioned preferred position with a play between the locking
element 8 and the locking groove 12 and a joint gap between the top
edges 16, 17.
[0075] Although only preferred embodiments are specifically
illustrated and described herein, it will be appreciated that many
modifications and variations of the present invention are possible
in light of the above teachings and within the purview of the
appended claims without departing from the spirit and intended
scope of the invention.
* * * * *