Note: Descriptions are shown in the official language in which they were submitted.
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MATTRESS CORE
Technical Field of the Invention
This invention relates to a mattress core and to a method of manufacturing a
mattress core.
Background of the Invention
Mattress cores, for example, have previously included an array of individually
pocketed
springs. In such mattress cores, each pocket spring typically includes a
spring encased
within a fabric sack. A variety of techniques have evolved for the manufacture
of
pocketed springs. Some of these techniques teach the creation of the pockets
within the
fabric plies prior to insertion of the wire spring and others teach the
insertion of the
coaxially compressed wire springs between the plies of the strip and the
subsequent
creation of the pockets by stitching the two plies to each other along
transverse lines
between adjacent springs. In either technique, the pocket is closed after the
insertion of the
spring, usually by stitching the two plies together along a line parallel to
the free edges of
the plies.
U.S. Patent No. 4,234,983, for example, teaches a manufacturing technique for
a mattress
core having an array of pocketed springs. This document teaches a technique
for
manufacturing a string of pocketed springs in which the overlaid fabric plies
are secured to
each other along the transverse and longitudinal lines of attachment to by
thermal welding
rather than by the use of stitching, as had conventionally been done. In
particular, this
document teaches a string of pocketed springs in which the pocket fabric is
thermally
weldable to itself so that the two plies of fabric of the folded strip in
which the pockets are
defined may be secured together without the necessity for stitching. In doing
so, a stronger
bond than is achieved when compared with sewing the same fabric material. At
the same
time, the elimination of any need for the thread and the sewing apparatus
which was
necessary to the manufacture of upholstery springs of this type.
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The above-mentioned techniques may improve efficiency of production mattress
cores.
However, the above-described techniques may not be able to adequately control
the
compression properties of the resultant mattress core to suit one or more load
requirements. To this end, it is not uncommon for two people to have different
preferences
when it comes to firmness of a mattress. That is, some people prefer a softer
mattress and
others prefer a harder mattress. This can make shopping for a mattress
difficult when the
mattress is to be shared by two people. This is particularly the case when the
mattress is
to be shared by a man and a woman having significantly different body sizes.
In this
situation, a mattress that is considered to have an adequate firmness by the
larger of the
two may be considered too hard for the lighter of the two. It is difficult to
find a single
mattress that satisfies the requirements of both parties.
The mattresses can, through wear and tear, visually sag when unloaded. That
is, when the
mattress is not bearing the weight of a person, for example. A sagging
mattress is not
typically aesthetically pleasing and would normally the owner to replace it.
It is generally
desirable to overcome problems associated with sagging mattresses.
Mattresses come with a variety of top layers attached to them. These top
layers, depending
on their design, add varying amounts of cushioning to the mattress. While the
construction
of the mattress core may be of a totally firm, for example, the top layer can
provide extra
padding. So called "Euro Tops" and "Pillow Tops", for example, are just two of
mattresses
that include such top layers.
The primary difference between Euro and Pillow is in the stitching, Euro tops
are stitched
directly to the mattress top with no additional materials or gap between the
top layer and
the mattress itself. A Pillow Top topping is affixed to a layer all its own,
which is attached
to the mattress proper, with a gap between the two. A Euro Top mattress lacks
the gap or
additional material between the mattress frame and the cushioned top. A Pillow
Top may
appear to sit higher and be thicker than a Euro Top and may feel slightly more
plush due to
the added space between the two parts of the mattress.
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It is generally desirable to improve the manufacturing steps involved in
construction of
Euro Top and Pillow Top mattresses. It is also desirable to manufacture Euro
Top and
Pillow Top mattresses having crowned upper surfaces. The crowned upper surface
is
generally aesthetically pleasing.
It is generally desirable to overcome or ameliorate one or more of the above
mentioned
difficulties, or at least provide a useful alternative.
Summary of the Invention
In accordance with one aspect of the invention, there is provided a mattress
core including:
(a) an array of strings of pocket springs extending in parallel across
the mattress core;
and
(b) a fastener coupling the array of pocket springs together,
wherein peripheral pocket springs located in peripheral sections of the array
are stepped
down from crown pocket springs which are framed by the peripheral pocket
springs.
Preferably, the crown pocket springs are substantially the same height.
Preferably, the peripheral pocket springs frame four sides of the crown pocket
springs.
Preferably, the peripheral pocket springs frame three sides of the crown
pocket springs.
Preferably, the array is formed in first and second halves, each having
peripheral pocket
springs located in non-adjoining peripheral sections of the array.
In accordance with one aspect of the invention, there is provided a mattress
including the
above described mattress core.
In accordance with another aspect of the invention, there is provided a method
of
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manufacturing a mattress core including the step of coupling a series of
strings of pocket
springs together with a fastener to form an array of strings of pocket
springs, wherein
peripheral pocket springs located in peripheral sections of the array are
stepped down from
crown pocket springs which are framed by the peripheral pocket springs.
Preferably, the crown pocket springs are substantially the same height.
Preferably, the array is formed in first and second halves, each having
peripheral pocket
springs located in non-adjoining peripheral sections of the array.
Preferably, the peripheral pocket springs are stepped down from the crown
pocket springs
on top and bottom sides of the mattress core.
Preferably, first and second halves of the array each include a central
cluster of pocket
springs, a rate of springs of pocket springs of the central cluster the first
one of said halves
being less than a rate of springs of pocket springs of the central cluster of
the second one of
said halves.
Brief Description of the Drawings
Preferred embodiments of the present invention are hereafter described, by way
of non-
limiting example only, with reference to the accompanying drawing in which:
Figure 1 is a plan view of a mattress core;
Figure 2 is an end view of the mattress core shown in Figure 1;
Figure 3 is a side view of a spring of the mattress core shown in Figure 1;
Figures 4a to 4f are plan views of a string of the mattress core shown in
Figure 1 arranged
in different stages of manufacture;
Figures 5a to 5c are plan views of sections of a string of the mattress core
shown in Figure
1 arranged in conditions of manufacture;
Figures 6a to 6c are plan views of the sections shown in Figures 5a to Sc
arranged in other
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conditions of manufacture;
Figures 7a to 7c are plan views of a string of the mattress core shown in
Figure 1 arranged
in different stages of manufacture;
Figures 8a and 8b are side views of a mattress core construction frame with
stings of the
mattress core shown in Figure 1 assembled thereon;
Figure 9 is a plan view of two halves of an array of pocket springs of the
mattress core
shown in Figure 1;
Figure 10 is a plan view of the two halves of the array of pocket springs
shown in Figure 9
framed in a box;
Figure 11 is a plan view of the two halves of the array of pocket springs
shown in Figure
10 arranged in another condition of manufacture; and
Figures 12 to 14 are end views of alternative mattress cores.
Detailed Description of Preferred Embodiments of the Invention
The mattress core 10 shown in Figures 1 and 2 forms part of a mattress (not
shown). The
mattress core 10 includes an array 12 of strings 14 of pocket springs 16
extending in
parallel across the mattress core 10, and a fastener 18 coupling the array 12
of pocket
springs 16together. As particularly shown in Figure 2, peripheral pocket
springs 16a
located in peripheral sections of the array 12 are stepped down from crown
pocket springs
16b which are framed by the peripheral pocket springs 16a.
Advantageously, the peripheral pocket springs 16a and the crown pocket springs
16b assist
in manufacture of Euro Top and Pillow Top mattresses (not shown). Further, the
crown
pocket springs 16b form a crown for the resultant mattress (not shown). The
crown results
in an aesthetically mattress and inhibits sagging of the mattress.
In order to provide a mattress that is suitable for two people that have
different preferences
when it comes to the firmness of a mattress, the mattress core 10 is formed in
first and
second halves 20a, 20b. A rate of springs 24 of crown pocket springs 16b of
the first half
20a of the mattress core is less than a rate of springs 24 of crown pocket
springs of the
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second half 20b of the mattress core. The rate of a spring is the change in
the force it
exerts, divided by the change in deflection of the spring. That is, it is the
gradient of the
force versus deflection curve. As such, the first half 20a of the mattress
will be softer than
the second half 20b of the mattress.
To further change the firmness of the mattress, first and second halves 20a,
20b of the
array 12 include respective central 22a, 22b; head 30a, 30b; and foot 32a, 32b
clusters of
crown pocket springs 16b. The rates of springs in the central 22a, 22b; head
30a, 30b; and
foot 32a, 32b clusters of crown pocket springs 16b can be selected to finely
tune the
firmness of the mattress core 10.
Any suitable combination of rates of springs for the central 22a, 22b; head
30a, 30b; and
foot 32a, 32b clusters of crown pocket springs 16b can be selected to finely
tune the
firmness of the mattress core 10. However, one particular combination is
described below
for illustrative purposes. Also, the description of the mattress core 10
provided below is
provided with reference to the strings 14 extending between a head 26 and foot
28 of the
mattress core 10. However, the strings 14 could, alternatively, extend across
the mattress
core 10.
Rates of springs 24 of the head and foot clusters 30, 32 of pocket springs of
the first half
20a of the array 12 are less than rates of springs 24 of central cluster 22a
of pocket springs
16. Similarly, rates of springs 24 of the head and foot clusters 30, 32 of
pocket springs of
the second half 20b of the array 12 are less than rates of springs 24 of
central cluster 22a of
pocket springs 16. As such, head and foot sections 30, 32 of the mattress core
10 are softer
than respective central sections 22a, 22b of the mattress core 10.
Springs 24 of the peripheral pocket springs 16a in the peripheral section 34
have a rate less
than the rate of springs 24 of the head and foot clusters 30, 32 of the first
and second
halves 20a, 20b of the array 12. As such, peripheral sections 34 of the
mattress core 10 are
softer than respective head and foot sections 30, 34 of the mattress core 10.
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The strings 14 include combinations of pocket springs 16 from the head, foot
and central
clusters 30, 32, 22a, 22b. Each pocket string 14 also includes peripheral
pocket springs
16a. For example, a centrally disposed string 14 of pocket springs in the
first half 20a
includes pocket springs in the head 30, central 22a and foot 32 clusters as
well as
peripheral pocket springs 16a. A string 14 of pocket springs 16 in the
peripheral section 34
of the first half 20a, includes border pocket springs 16b only.
The first and second halves 20a, 20b of the mattress core 10 are separated by
a barrier 36.
The barrier 36 is a section of foam. Alternatively, the barrier is any other
suitable
resiliently compressible material.
The fastener 18 includes top and bottom rectangular peripheral bands 18a, 18b
respectively
coupled to top and bottom sections 40a, 40b of peripheral pocket springs 16a
of the array
12. The top and bottom rectangular peripheral bands 18a, 18b are respectively
coupled to
top and bottom sections 40a, 40b of peripheral pocket springs 16b with clips
42. As
described below in further detail, opposed articular surfaces 74 of pocket
springs 16 in
opposed strings 14 of the array 12 are coupled together with an adhesive.
As particularly shown in Figure 3, the springs 24 are preferably helical
coils. The springs
24 formed using known apparatus (not shown) which takes a continuous length of
metal
wire and produces a helical coil. The coils are made from annealed metal and
then treated
with heat after fabrication. The apparatus used to manufacture the springs is
know in the
art and is not described here in detail.
The apparatus produces springs having different rates for use in the different
sections of
the mattress core. That is, the apparatus produces springs 24 for the pocket
springs 16
having the following thickness:
a. Springs 24a of the border 34 = 2.5mm to 5mm;
b. Springs 24b of the head cluster 30 = lmm to 2.3mm;
c. Springs 24c of the foot cluster 32 = lmm to 2.3mm;
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d. Springs 24di of the first central cluster 22a = lmm to 2.3mm; and
e. Springs 24dii of the second central cluster 22b = lmm to 2.3mm.
As above-mentioned, the springs 24di for the central cluster 22a have a lesser
rate than
springs 24dii for the central cluster 22b. In order to facilitate this, the
wire used for the
springs 24di of the central cluster 22a is thinner than the wire used to
manufacture the
springs 24dii of the central cluster 22b.
A description of the steps in manufacturing the peripheral strings 14a, 14b,
14w, 14x are
set out below with reference to Figures 4a to 4f:
a. As particularly shown in Figure 4a, four sections 44 of material are
cut, one for
each for border sting 14a, 14b, 14w, 14x of pocket springs 34. Preferably, the
material is
non-woven. Alternatively, the material is cotton. Preferably, each section 44
of material
has a length "L" and a height "2H".
b. As particularly shown in Figure 4b, each one of the four sections 44 is
folded in
half along a lengthwise median crease 46 so that the top half overlies the
bottom half. The
top and bottom halves of the material 20 are then stitched together with
spaced apart seams
48 in the manner shown in Figure 4c. The seams 48 extend substantially
perpendicularly
to the direction of the above-mentioned crease, thereby creating pockets 16
for the springs
24. As shown in Figures 4b, a template 50 is preferably used to indicate the
seam
positions.
c. As particularly shown in Figures 4d, the springs 24 for the border
strips 14 are then
inserted into the pockets 16 of the material 44. Each spring 24 is arranged so
that its
longitudinal axis DLAs is perpendicular to the longitudinal axis Dud) Of the
pocket 16.
d. The top and bottom halves of each section 44 of material are then
sewn together
along a common seam 54, in the manner shown in Figure 4e, so as to close the
pockets 16.
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e. The
springs 24 of each section 44 of material are then rotated in respective
pockets
16 so that the longitudinal axes DLAs of the springs 24 are parallel to the
longitudinal axes
DLAp of the pockets 16. In doing do the springs 24 resiliently expand within
the pockets 16
in the manner shown in Figure 4f.
A description of the steps in manufacturing the central strings 14c to 14L of
the first half
20a of the mattress core 10 are set out below with reference to Figures 5a to
8c:
a. As
shown in Figures 5a to 5c, material is cut for the peripheral 56, head 58,
foot 60
and central 62 sections of the central strings 14c to 14L of the first half
20a in the
following manner:
i.
twenty peripheral sections 56 of material, each section 56 having a length
"2/34 L" and a height "2H".;
i ii. ten
head sections 58 of material, each section 58 of material has a length
"10/34 L" and a height "211 + 2C";
iii. ten foot sections 60 of material, each section 60 of material has a
length
"10/34 L" and a height "2H + 2C";
iv. ten central sections 62 of material, each section 62 of material has a
length
"10/34 L" and a height "2H + 2C".
b. As
particularly shown in Figures 6a to 6c, each one of the sections 58 to 62 is
folded in half along a lengthwise median crease 64 so that the top half
overlies the bottom
half. The top and bottom halves of the material are then stitched together
with spaced
apart seams 66. The seams 66 extend substantially perpendicularly to the
direction of the
above-mentioned crease 64, thereby creating pockets 16 for the springs 24. A
template 50
is preferably used to indicate the seam positions.
c.
Material for each central string 14c to 14L is sewn together so that central
sections
62 separate head and foot sections 58, 60 and that peripheral sections 56 are
coupled to
free ends of respective head and foot sections 58, 60 in the manner shown in
Figure 7a.
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The combined length of each central string 14c to 14L is "U.
d. For each central string 14c to 14L, the following steps are performed in
the manner
shown in Figure 7b:
i. The springs 24a for the peripheral sections 56 are inserted into the
pockets
16 of the peripheral sections 56;
The springs 24b for the head section are inserted into the pockets 16 of the
head sections 58;
iii. The springs
24c for the foot section are inserted into the pockets 16 of the
foot sections 60;
iv. The springs 24di for the central section are inserted into the
pockets 16 of
the central sections 62.
Each spring 24 is arranged so that its longitudinal axis DLAs is perpendicular
to the
longitudinal axis DiAp of the pocket 16.
e. The top and bottom halves of each string 14c to 14L are then sewn
together along a
seam 68 so as to close the pockets 16.
f. The springs 24 of each string 14c to 14L are then rotated in respective
pockets 16
so that the longitudinal axes DLAs of the springs 24 are parallel to the
longitudinal axes
DLAp of the pockets 16. In doing do the springs 24 resiliently expand within
the pockets 16
in the manner shown in Figure 7c.
The above-described steps are then performed to manufacture the central
strings 14m to
14v of the second half 20b of the mattress core 10. However, springs 24dii are
used for the
central section 62 instead of the springs 24di.
Once all of the strings 14a to 14x have been manufactured, first half 20a of
the array 12 of
pocket springs 16, as shown in Figure 9, is then manufactured by:
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a. Arranging the first string 14a of pocket springs 16 along a footing 70
of a mattress
core construction frame 72 in the manner shown in Figure 8a;
b. Applying an adhesive to the superior articular side 74 of each pocket
spring 16 of
the first string 14a of pocket springs 16;
c. Arranging the next string 14b of pocket springs 16 over the previous
string 14a of
pocket springs 16, in the manner shown in Figure 8b;
d. Applying an adhesive to the superior articular side 74 of each pocket
spring 16 of
the next string 14b of pocket springs 16;
e. Repeating steps c and d until all strings 14a to 14L of the first half
20a of the array
12 have been coupled together.
The above-described steps are then repeated to manufacture the second half 20b
of the
array 12 of pocket springs 16 shown in Figure 9 using the strings 14m to 14x.
The adhesive is preferably a hot melt glue. Alternatively, any suitable
adhesive could be
used. The adhesive is preferably applies using a glue gun.
The two halves 20a, 20b of the array 12 of pocket springs 16 are then framed
in a box 76 in
the manner shown in Figure 10. The box 76 is of suitable size and shape to fit
around the
periphery of the array 12 in the manner shown. A barrier 78 is arranged
between the two
halves 20a, 20b of the array 12 as they are placed in the box 76. The box 76
exerts a
compressive force on the array 12.
Once arranged in the box 76, the above-described upper and lower rectangular
peripheral
borders 18a, 18b are arranged around the upper and lower peripheral edges 40a,
40b of
pocket springs 16 of the array 12 in the manner shown in Figure 11. The
borders 18a, 18b
are preferably made of metal. Alternatively, the borders are made of plastic.
The upper
and lower borders 18a, 18b are coupled to upper and lower sections of springs
24 of the
peripheral pocket springs 16 with fasteners 80. The fasteners 80 are
preferably metal
couplings.
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Advantageously, the mattress core has the following dimensions:
210 cm
200 cm
H = 10 to 30 cm
1 to 5 cm
Alternative mattress cores 100, 200, 300 are shown in Figures 12 to 14. The
mattress core
100 is constructed in accordance with the above described method steps.
However, the
mattress core 100 is formed as a single unit rather than two halves. The
mattress core 200
is constructed in accordance with the above described method steps. However,
the
peripheral pocket springs 16a are stepped down from upper and lower sides of
the mattress
core 200. The mattress core 300 is constructed in accordance with the above
described
method steps. However, mattress core 300 is formed as a single unit rather
than two
halves and the peripheral pocket springs 16a are stepped down from upper and
lower sides
of the mattress core 200.
Many modifications will be apparent to those skilled in the art without
departing from the
scope of the present invention
Throughout this specification, unless the context requires otherwise, the word
"comprise",
and variations such as "comprises" and "comprising", will be understood to
imply the
inclusion of a stated integer or step or group of integers or steps but not
the exclusion of
any other integer or step or group of integers or steps.
The reference to any prior art in this specification is not, and should not be
taken as, an
acknowledgment or any form of suggestion that the prior art forms part of the
common
general knowledge in Australia.
