[0001] The present invention concerns flooring according to the preamble of Claim 1.
[0002] Flooring of the kind indicated above has, over the years, been widely used in widely
differing applications. A particularly extensive sector of use is sporting or athletics
floorings, the two terms in question being used here in their widest sense so as to
include installations such as gymnasiums, fitness or medical centres, consulting rooms
and the like.
[0003] Figure 1 illustrates, in an ideal vertical transverse section, a flooring according
to the prior art. In particular, it shows flooring sold by the Applicant under the
commercial name SPORTFLEX SUPER X™. This flooring has been widely used, for example,
for athletics tracks and the like.
[0004] The flooring in question is constituted by a generally laminar or sheet-like structure
1, in which it is possible to distinguish:
- a tread layer 2 intended to face upwards with the flooring 1 in its forward orientation,
and
- a set of support formations 3 having a structure that can be defined generally as
pendunculate.
[0005] In practice, the flooring 1 is produced, for example, from mixtures of isoprene rubbers
in one or more successive calendering operations. In this way it is possible to give
the upper face 4 of the tread layer 2 a generally corrugated form, the primary function
of which is to prevent slipping. The set of support formations 3 is usually a reticular
structure comprising a transverse grid formed by a set of transverse ribs 5 connected
to each other by a longitudinal grid formed by respective orthogonal ribs 6 substantially
comparable to formations which extend in the form of bridges connecting adjacent ribs
5. The term "transverse" is intended here to refer to the preferred direction of running
or walking on the flooring 1 which - usually - also corresponds to the direction in
which the calendering operation is carried out.
[0006] In the particular arrangements according to the prior art, as illustrated in Figure
1, the height or depth of these bridges 6 (with reference to the general plane of
the tread layer 2) is slightly less than that of the transverse ribs 5. In this particular
embodiment, the ribs 5 thus constitute a kind of principal grid in the reticular structure
of the formations 3, while the bridges 6, usually aligned to form respective longitudinal
ribs of the flooring, orthogonally of the transverse ribs 5, constitute a kind of
strengthening reinforcement. Bearing in mind that this is, however, identically applicable
to the arrangement according to the invention, it can be stated that this particular
configuration of the support formations 3 constitutes a preferred, although not an
obligatory, choice. In fact, flooring exists according to the prior art in which the
aforesaid support formations 3 are in the form of a uniform, regular structure (with
ribs 5 and 6 of equal height) or, in general terms, as sets of isolated peduncular
support formations, not configured as continuous or substantially continuous ribs.
[0007] It is also noted (this consideration also applies in an identical way to the invention
which will be better described below) that producing the tread layer 2 from a material
substantially similar to, although usually with a different formulation from the material
constituting the support formations 3, is not imperative. For example, the tread layer
2 can be formed from a material that is completely different from that of the support
formations 3, for example, in the form of a sheet of rigid or substantially rigid
material.
[0008] An important characteristic of the flooring according to the invention considered
here is that the resilience (usually understood in the sense of an elastic resilience)
of the flooring 1 which is intended to be laid on a rigid foundation such as, for
example, a layer of asphalt, bitumen or cement, is dictated primarily by the resilience
of the support formations 3.
[0009] The term "primarily" is intended to mean that, even in an arrangement such as that
illustrated in Figure 1, the characteristics of the tread layer 2 can have a certain
bearing on the resilience of the flooring 1, this being largely dictated by the resilience
of the support formations 3.
[0010] In practice, the formations in question (this applies both to the transverse ribs
5 and the longitudinal ribs 6) all lie with their principal direction orthogonal to
the general plane of the tread layer 2. From the point of view of resilience, they
operate as elastic elements similar to compression springs interposed between the
tread layer 2 and the foundation on which the flooring 1 is laid.
[0011] The characteristics of a flooring of the type described above can be identified in
a quantitatively precise manner by applying the elastic impact test of the DIN standard
18035/6. This standard, together with the DIN standard 18032/2, enables a parameter,
KA (an abbreviation of the German word Kraftabbau), to be defined. This coefficient
corresponds substantially to a characterisation, in percentage terms, of the behaviour
of the flooring when subjected to a weight of standardised dimensions falling onto
it, with reference to the behaviour manifested as the result of the same stress on
a rigid surface, typically made of cement.
[0012] Flooring for sporting use, especially for athletics tracks, usually have a KA coefficient
lying between about 35 and 50%. This range of values is particularly required by the
text "Track and Field Facilities Manual", edited by the International Amateur Athletic
Federation (1995 edition). The lower value of the aforesaid range corresponds to flooring
characterisable as rather "hard", while the upper limit corresponds to flooring that
is rather "soft" when comparing the stresses of walking or running.
[0013] Referring, for simplicity, to the production of athletics tracks (it is, however,
noted once again that the applicability of the invention is not limited to this field),
flooring according to the prior art, as illustrated in Figure 1, behaves in a substantially
uniform manner independently of the specific way in which stress is applied or, more
specifically, of its interaction with the body of the athlete.
[0014] The interactions are usually very different, for example, depending on the discipline
practised and/or the style of running adopted. For example, a long or middle distance
runner usually adopts a running style in which each step involves a complete cycle
of contact (heel-sole-toes) of the foot. On the other hand, the sprinter or jumper,
such as the long jumper or triple jumper, adopts a running profile that is extended
forward with an interaction of the foot with the track that is practically limited
to the toes only, with a very short foot-track contact time in comparison with the
contact time typical of the long distance runner.
[0015] It follows from this that, for example, an athletics track formed with flooring of
the type illustrated in Figure 1 must necessarily reconcile the various requirements
in terms of flexibility, having to match the requirements of, for example, long or
middle-distance runners, who generally like a fairly soft flooring so as to limit
fatigue of the joints consequent on a long run, and the demands of sprinters or jumpers
who, on the other hand, tend to like a fairly hard track to optimise the transmission
of the propulsion forces exerted by the athlete on the ground. In general, however,
all athletes like to be able to carry out their warm up runs on a very soft base so
as to avoid tiring their joints and muscles.
[0016] The object of the present invention is to produce flooring of the type indicated
above that is fully capable of satisfying these requirements that are, in themselves,
contradictory.
[0017] According to the present invention, this object is achieved by flooring having the
characteristics defined in the following claims.
[0018] The invention will now be described, purely by way of non-limitative example, with
reference to the accompanying drawings, in which:
Figure 1, which concerns the prior art, has already been described above;
Figure 2 illustrates, in a sectional view substantially corresponding to the sectional
view of Figure 1, the characteristics of flooring produced according to the invention;
and
Figures 3 to 5 illustrate different kinds of interaction between the flooring according
to the invention and an athlete walking or running on the flooring itself.
[0019] In Figures 2 to 5, the same reference numerals as have already been used with reference
to the description of Figure 1 have been used to indicate parts or elements that are
identical or functionally equivalent to those already described with reference to
Figure 1.
[0020] An exception is made for the different elements referred to specifically in the following
description, where the same considerations as indicated above in relation to the flooring
of Figure 1, especially as regards the different intended uses and the possible variants
in production, apply in identical manner to the flooring according to the invention.
[0021] Therefore, it can be easily be appreciated from a comparison of Figure 1 and Figure
2 that the salient characteristic of the arrangement according to the invention is
the fact that at least some of the support formations 3, and especially the ribs 5
(defined above as "transverse"), are not disposed with their principal direction of
extension orthogonal to the tread layer 2, but are generally inclined with respect
to this plane. The term "direction of extension" naturally means the direction along
which the ribs 5 (or, more precisely, their profile in transverse section) extend
away from tread layer 2. In particular, the ribs 5 extend with their respective direction
of extension - monotonically - oblique with respect to the plane of the tread layer.
The term " monotonically" is intended to indicate the fact that the ribs 5 are inclined
in the same direction and not in alternate directions.
[0022] More precisely, the ribs 5 are disposed with their general direction of extension
X5 forming an angle α with respect to the direction of the normal N with respect to
the general plane of extension of the tread layer 2.
[0023] The value of the angle α is chosen from a range which is typically between approximately
25° and 50°, and preferably between approximately 35° and 40°.
[0024] The values indicated above correspond to choices identified following a first set
of experimental tests made by the Applicant. The exact value from time to time adopted
(to be understood in general terms as an average value of inclination, in that, variations
in the value of the angle α from rib to rib 5 can arise in the production process)
can be determined selectively as a function of the specific manners of use envisaged
for the flooring.
[0025] The precise criteria for this choice can be better understood by referring to the
different user/flooring interactions, illustrated with reference to Figures 3 to 5.
[0026] It will be recalled that flooring of the type illustrated in Figure 2 can be produced
using the same materials as are currently used to produce similar floorings according
to the prior art, utilising a simple calendering procedure or a multi-stage procedure
generally identical to those utilised for the production of floorings according to
the prior art. The result of providing the ribs, in particular, the longitudinal ribs
5 (in the embodiment illustrated here, it is supposed that the longitudinal ribs 6
maintain their generally orthogonal extension with respect to the tread layer 2) with
the desired angle can be obtained, according to an arrangement tested satisfactorily
by the Applicant, simply by providing the calendering roller for embossing the design
on the support ribs 3 with channels or tracks corresponding with and complementary
to the ribs 5, with their principal direction of extension, in the sense of their
depth, oriented in a direction at least generally inclined with respect to the respective
diameter of the calendering roller.
[0027] In general, for the production of flooring according to the invention, reference
can be made to the criteria and principles conventionally adopted for the production
of sports floorings. In this respect, reference may usefully be made, for example,
to the appendix entitled "I.A.A.F. Performance Specifications for Synthetic Surfaced
Athletics Tracks (Outdoor)" contained in the manual edited by the I.A.A.F., already
indicated above, and to the technical requirements of the DIN standard 18035/6. These
criteria and principles do not require explicit explanation here.
[0028] By way of non-limitative example, the flooring 1 illustrated in Figure 2 can have
the following characteristics:
- depth (measured between the surface 4 of the tread layer 2 and the foundation L in
the absence of stress): 13mm;
- depth of the tread layer: typically 6-7mm;
- number of ribs 5 per unit of length: 80-100/metre;
- width of the section of the ribs (measured orthogonally to the median axis): approximately
7mm.
[0029] Figure 3 illustrates schematically the response of flooring according to the invention
to a force applied in a generally vertical direction. This may be, for example, the
force applied by an athlete running on the flooring 1, adopting the pace usually adopted
by long or middle distance runners. In particular, Figure 3 illustrates the interaction
of the heel of the foot of such an athlete, which descends vertically onto the flooring
1, compressing it against the rigid substrate L on which the flooring is laid. Substantially
similar behaviour is also seen when the entire sole of the foot is set down vertically
on the flooring 1.
[0030] The consequent elastic deformation (the resilient behaviour) of the flooring 1 is
significantly determined more by the flexing of the ribs 5 with respect to their principal
axis of extension, than by the longitudinal compression thereof. This fact is entirely
understandable since, in the situation illustrated in Figure 3, the deformation stress
of the flooring 1 translates into a bending moment applied to the ribs 5 constituting
the transverse grid of the support formations 3.
[0031] The rather soft nature of the flooring derives from this.
[0032] For example, tests conducted by the Applicant show that flooring produced according
to the invention (therefore, with the main ribs 5 inclined with respect to the tread
layer 2) using dimensions of the ribs 5 corresponding to those of a flooring according
to the prior art, but with the ribs 5 orthogonal with respect to the tread layer 2,
has, with respect to this latter, a value for the coefficient KA that is approximately
5% greater in absolute terms. In other words, if flooring according to the prior art
(Figure 1) has a value for KA equal to approximately 35-37%, flooring formed according
to the invention with transverse ribs 5 substantially of the same size but inclined
with respect to the tread layer has, with respect to the tread layer, a value of KA
(always measured according to the DIN standard 18035/6) equal to 40-42%.
[0033] On the other hand, Figure 4 illustrates schematically the behaviour of flooring 1
according to the invention when subjected to a force of the type imparted by a sprinter
or jumper running on the flooring 1. This is usually at a very fast pace such that
the athlete in practice runs on his toes, applying to the flooring 1 (by means of
the friction of the sole of the shoe, possibly enhanced by the spikes that are usually
present on the athlete's shoes penetrating the body of the flooring) a stress that
is no longer orthogonal, but inclined with respect to the plane of the tread layer
2.
[0034] The aforesaid values of the possible inclination of the ribs 5 (values of the angle
α of Figure 2) correspond in a complementary manner to the typical values of the inclination
of the aforesaid stress deriving from the forward inclination adopted by the athlete
while running.
[0035] Due to the consequent alignment - or substantial alignment - of the direction of
the force applied by the athlete with the direction of inclination of the ribs 5,
the force deforming the flooring 1 translates substantially into a longitudinal force
along the ribs 5. Longitudinal force naturally means a force substantially aligned
with the direction of maximum extension (of the section profile) of the ribs 5.
[0036] When subjected to a force as illustrated in Figure 4 (that is, in practice, with
a direction of running such that the ribs 5 extend from the tread layer 2 "backwards"
with respect to the direction of running), the flooring 1 is generally harder than
when the force is applied according to the modality of Figure 3.
[0037] In practice, tests conducted by the Applicant show that the same flooring which,
when subjected to a force according to the typical manner of the DIN standard 18035/6
(in practice, according to the manner of use of Figure 3) has a value of KA equal
to approximately 40-42% while, if utilised according to the modalities illustrated
in Figure 4, characterised of resilience substantially comparable to that shown experimentally
by running on a flooring produced according to the prior art with a value of KA equal
to approximately 35-37%.
[0038] From the above, it can be concluded that the flooring according to the invention
has characteristics of differential resilience, demonstrating the desired "softness"
to the step of a long or middle-distance runner, and the desired "hardness" to the
rapid pace of a sprinter or jumper who takes a run up, for example, for a long jump
or triple jump.
[0039] Figure 5 illustrates the behaviour of flooring 1 according to the invention when
subjected to stress in yet further different ways, in particular, with a direct run
in the opposite direction to the direction referred to in Figure 4.
[0040] Figure 5 illustrates a method of running substantially similar to that of Figure
4 but in the opposite direction, that is, such that the ribs 5 extend from the tread
layer 2 "forwards" with respect to the direction of running. Consequently, Figure
5 also relates to running "on toes". In this case, however, the stress applied to
the flooring is inclined with respect to the tread layer 2 in a direction which tends
to be substantially orthogonal with respect to the principal direction of extension
(of the section profile) of the ribs 5.
[0041] Under these conditions, the aforesaid ribs are stressed more or less exclusively
flexed, with a bending stress preferably localised at the base or proximal part of
the ribs 5 themselves. According to the preferred embodiment of the invention, this
is the zone in which the ribs 5 have the smallest transverse section. This fact can
clearly be seen in the various figures, and particularly in Figure 2 where the "tear-drop"
shape of the section of the ribs 5 is illustrated.
[0042] In the conditions of use of Figure 5, the flooring 1 is at least slightly softer
than that in the stress conditions of Figure 3, while being stressed in ways typical
of a fast run. The modality of use demonstrated in Figure 5 lends itself to being
used in excellent manner, for example, during warm up runs when the athletes wish
to limit the fatigue of the joints. To this end, it is possible to envisage laying,
next to a track for the competitions (with the ribs facing "backwards" with respect
to the direction of running), a portion of warm up track in which the ribs 5 are facing
in the opposite direction. Alternatively, in an even simpler manner, the athletes
can utilise the same competition flooring as a warm up track by running it in the
opposite direction to the direction of running adopted during the competitions.
[0043] It is entirely clear that the effect of providing the flooring 1 qualities of differential
flexibility can be achieved in different ways from that adopted in the particular
embodiment illustrated here, in which this effect is obtained by inclining the principal
direction of extension (of the transverse section profile) of the ribs 5. Therefore,
to give by way of example some possible embodiments of the invention, the inclined
support formations could take the form, at least in part, of individual feet having
their axes inclined with respect to the tread layer, or they could be constituted
by shorter ribs, for example, distributed in a stepped arrangement on the lower face
of the tread layer. Again, although the above description referred to the possibility
of providing a variation in the flexibility of the flooring in a single direction
(in practice, orthogonal to the direction of extension of the ribs 5), the same effect
could be pursued in several directions. It follows that, with the principle of the
invention remaining the same, the details of construction and the embodiments can
be widely varied with respect to that described and illustrated, without by this departing
from the ambit of the present invention.
1. Flooring (1) comprising a tread layer (2) extending in a given plane and support formations
(5, 6) extending from the said tread layer (2) in respective directions of extension
(X5), characterised in that at least some of the said support formations (5) extend
with their respective direction of extension (X5) monotonically inclined with respect
to the plane of the tread layer (2).
2. Flooring according to Claim 1, characterised in that at least some of the said support
formations (5) extend with their respective direction of extension (X5) forming an
angle of between approximately 25° and 50° with respect to the normal (N) to the tread
layer (2).
3. Flooring according to Claim 2, characterised in that at least some of the said support
formations (5) extend with their respective direction of extension (5) forming an
angle of between approximately 35° and 40° with respect to the normal (N) to the tread
layer (2).
4. Flooring according to any preceding claim, characterised in that the said support
formations (5, 6) are distributed as at least a first and second grids, respectively
transverse (5) and longitudinal (6) with respect to a principal direction of use of
the flooring (1), and in that at least some of the said support formations (5) extending
with their respective direction of extension inclined with respect to the plane of
the tread layer (2) are comprised in the said transverse grid (5).
5. Flooring according to any preceding claim, characterised in that the at least some
of the said support formations (5) are produced in that form of ribs extending from
the said tread layer.
6. Flooring according to Claim 5, characterised in that the said ribs are substantially
continuous ribs.
7. Flooring according to Claim 4 and Claim 6, characterised in that the said substantially
continuous ribs (5) are comprised in the said transverse grid, while the said longitudinal
grid (6) comprises elements extending in the form of bridges between adjacent ribs.
8. Flooring according to Claim 7, characterised in that the said elements extending in
the form of bridges (6) are arranged as respective longitudinal ribs.
9. Flooring according to Claim 4, characterised in that the support formations of the
said longitudinal grid (6) have a height, with reference to the said given plane of
the tread layer (2), less than the comparable height of the support formations of
the transverse grid (5).
10. Flooring according to any preceding claim, characterised in that the said at least
some of the said support formations (5) have a proximal part constituting a portion
with a smaller transverse section than the support formations (5) themselves.
11. Flooring according to any preceding claim, characterised in that at least the said
support formations (5, 6) are constituted by an elastomeric mass.
12. Flooring according to Claim 11, characterised in that both the said tread layer (2)
and the said support formations (5, 6) are constituted by an elastomeric mass.
13. Flooring according to any preceding claim, characterised in that at least the said
tread layer is constituted by a mass of calendered material.