U.S. patent application number 10/569300 was filed with the patent office on 2007-01-04 for cushion material formed of spring-structured resin-molded product, manufacturing method for the cushion material, and mold used for the manufacturing method.
Invention is credited to Tatsumi Kobayashi, Yuichiro Nakamura, Sadao Nishibori, Maki Shirai.
Application Number | 20070001336 10/569300 |
Document ID | / |
Family ID | 34204224 |
Filed Date | 2007-01-04 |
United States Patent
Application |
20070001336 |
Kind Code |
A1 |
Nishibori; Sadao ; et
al. |
January 4, 2007 |
Cushion material formed of spring-structured resin-molded product,
manufacturing method for the cushion material, and mold used for
the manufacturing method
Abstract
There is provided a method for producing a cushion material
composed of a resin molded article with a spring structure which is
so moldable as to allow the mold take any shape and size, is cheap,
and resistant to collapsing, does not cause fatigue even after
prolonged use, and has high shock absorbing capability and load
capacity, and thus suitably used as a material of any supports on
which one can sit, rest or mount such as seats of automotive
vehicles, motor cycles, bicycles, electric trains, and aircraft,
saddles for horse riding, chairs, sofas and beds, and a method for
producing a cushion material requiring only a low cost for its
disposal.
Inventors: |
Nishibori; Sadao; (Tokyo,
JP) ; Kobayashi; Tatsumi; (Saitama, JP) ;
Shirai; Maki; (Tokyo, JP) ; Nakamura; Yuichiro;
(Tokyo, JP) |
Correspondence
Address: |
DONN K. HARMS;PATENT & TRADEMARK LAW CENTER
SUITE 100
12702 VIA CORTINA
DEL MAR
CA
92014
US
|
Family ID: |
34204224 |
Appl. No.: |
10/569300 |
Filed: |
August 26, 2003 |
PCT Filed: |
August 26, 2003 |
PCT NO: |
PCT/JP03/10798 |
371 Date: |
February 23, 2006 |
Current U.S.
Class: |
264/103 ;
264/163; 264/324 |
Current CPC
Class: |
D04H 3/037 20130101;
D04H 3/16 20130101; A47C 27/122 20130101; B62J 1/26 20130101; A47C
27/12 20130101; B62J 1/18 20130101 |
Class at
Publication: |
264/103 ;
264/324; 264/163 |
International
Class: |
D21J 3/00 20060101
D21J003/00 |
Claims
1. A method for producing a cushion material composed of a resin
molded article having a spring structure, comprising the steps of:
forming a three-dimensional structure with voids at a predetermined
bulk density by contacting, entwining, and gathering ad] acent ones
of random loops or curls of solid and/or hollow continuous
filaments and/or short filaments made from a thermoplastic resin;
heating a male die or a female die, or a female die and/or the
three-dimensional structure to a temperature sufficiently high to
soften the three-dimensional structure; allowing the male die to
intimately contact with the female die so as to tightly compress
the three-dimensional structure; and hardening the
three-dimensional structure by cooling.
2. A method as described in claim 1 for producing a cushion
material composed of a resin molded article having a spring
structure wherein: superfluous edges protruded from the
three-dimensional structure into the stroke between the two mating
dies are cut with a heat cutter so that the edges are cut out and
open ends of edge filaments are fused together.
3. A method as described in claim 1 for producing a cushion
material composed of a resin molded article having a spring
structure wherein: a base to which the resin molded article with a
spring structure is attached serves as a male die, and the male die
is allowed to intimately contact with a female die so as to tightly
compress the three-dimensional structure; and the three-dimensional
structure is hardened by cooling.
4. A cushion material composed of a resin molded article having a
spring structure obtained by overlapping two or more layers of
sheets each comprising a three-dimensional structure having a same
or different spring property, wherein: the three-dimensional
structure is formed by contacting, entwining, and gathering
adjacent ones of random loops or curls of solid and/or hollow
continuous filaments and/or short filaments made from a
thermoplastic resin; and the three-dimensional structure is heated
in a male die or in a female die to a temperature sufficiently high
to soften it, compressed via closure of the two mating dies, and
allowed to harden by cooling.
5. A cushion material as described in claim 4 composed of a resin
molded article having a spring structure wherein the spring
property is determined by the density, material and/or filament
diameter of the three-dimensional structure.
6. A cushion material as described in claim 1 composed of a resin
molded article having a spring structure wherein the volume of the
resin molded article with a spring structure can be altered by
adjusting stroke of the male die when the female die has a deeply
set receptive base.
7. A cushion material as described in claim 1 composed of a resin
molded article having a spring structure wherein, out of the two
mating dies, at least the female die is made from concrete.
8. A concrete-made female die used for molding a resin molded
article with a spring structure which is obtained by preparing a
framework according to a master female die effective for molding a
resin molded article with a spring structure, pouring concrete
paste into the space within the framework, and allowing the
concrete paste to harden.
9. A cushion material as described in claim 1 composed of a resin
molded article having a spring structure wherein the vertical
movement of at least one of the two mating dies is achieved by a
pantograph jack.
10. A cushion material composed of a resin molded article having a
spring structure comprising a three-dimensional structure, wherein:
the three-dimensional structure is formed by contacting, entwining,
and gathering adjacent ones of random loops or curls of solid
and/or hollow continuous filaments and/or short filaments made from
a thermoplastic resin; and the three-dimensional structure has, on
both its top and bottom surfaces, two or more bulges formed on
predetermined linear areas by stitching the boundaries of each area
using a thread of a thermoplastic resin, and shortening the thread
by pressure.
11. A method for producing a cushion material composed of a resin
molded article having a spring structure, comprising the steps of:
extruding a melt of a thermoplastic resin into filaments and
contacting, entwining, and gathering adjacent ones of random loops
or curls of continuous filaments, thereby forming a
three-dimensional structure containing voids at a predetermined
bulk density; cutting the periphery of the three-dimensional
structure or a resin molded article with a spring structure to give
a U- or V-shaped profile, and stitching the thus formed edges with
a thread of a thermoplastic resin; and stitching with a thread of a
thermoplastic resin the boundaries of predetermined linear areas on
the top and bottom surfaces of the three-dimensional structure, and
shortening the thread by pressure.
12. A method as described in claim 11 for producing a cushion
material composed of a resin molded article having a spring
structure, comprising the steps of: placing the three-dimensional
structure on a female die; heating the female die and/or the
three-dimensional structure to a temperature sufficiently high to
soften the three-dimensional structure; allowing a male die to
intimately contact with the female die so as to tightly compress
the three-dimensional structure; cooling the three-dimensional
structure to confer a constant spring property thereto; and
stitching with a thread of a thermoplastic resin the boundaries of
predetermined linear areas on the top and bottom surfaces of the
three-dimensional structure, and shortening the thread by pressure.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] The present invention relates to a cushion material composed
of a resin molded article having a spring structure, method of
producing the same, and dies used in manufacture of the cushion
material, more particularly to a method for producing a resin
molded article with a spring structure which is excellent in shock
resistance and load capacity, and has an ability to meet specific
and non-specific needs in terms of shape and size in various
industrial fields, that is, a material suitably used for producing
any supports on which one can sit, rest or mount such as seats of
automotive vehicles, motor cycles, bicycles, electric trains, and
aircraft, saddles for horse riding, chairs, sofas and beds, and to
a method for producing a cushion material which requires a low cost
and burden for its disposal, and low production cost by simplifying
production facilities, and improves the precision of molding, and
apparatuses necessary for producing the cushion material.
[0003] 2. Background Art
[0004] At present, a polyurethane foam is a mainstream material of
cushions for seats and beds of automotive vehicles, motor cycles,
bicycles, electric trains and aircraft. Generally, cushions are
used in some form or another in any supports on which one can sit,
rest or mount regardless of whether they are exposed to vibrations
during use or not. Indeed, polyurethane foam is widely used in
various applications, and the wide spread of this material is
ascribed to its being comparatively free from problems in
production and cost.
[0005] One of such cushion materials is disclosed, for example, in
Japanese Patent No. 2995325 which proposes a cushion pad for the
seat of automobiles. Of the cushion pad in question, a seat surface
part is formed of a high resilience foam having a one layer
structure, and the high resilience foam is made of a polyurethane
foam which contains 10 wt % or less of tolylene diisocyanate (TDI),
and the remainder isocyanate formed by diphenylmethane
diisocyanate. Japanese Patent No. 2548477 proposes a cushion
structure obtained by fusing polyester fibers with a high melting
point to each other via a thermoplastic elastomer with a low
melting point. A cushion is proposed in Japanese Laid-Open Patent
Publication (Kokai) No. 2000-51011, which is obtained by partially
bonding synthetic fibers and natural fibers of 1 to 20 deniers with
each other, via a synthetic rubber adhesive or cross-linking
polyurethane.
[0006] Generally, when a man sits on a seat made of polyurethane
foam, his weight tends to concentrate in one point so much that
polyurethane foam beneath the point sinks deeply. Thus, his balance
becomes unstable, and he gets fatigued if he sits on the seat for a
long time. The main reason for this is as follows. Manufacture of a
product of a polyurethane foam is achieved by placing a foaming
material in a mold, and foaming the material uniformly, to give a
product uniform in density and strength. With this manufacture it
is difficult to obtain a product of which parts are modified in
density and strength according to the functions they are assigned.
Furthermore, because polyurethane foam is so soft and elastic that,
when man rests his weight on a seat made of polyurethane foam, he
feels an upward thrust on his buttock, touching on a hard bottom,
and vertical swing, and his feet may become numb and strongly tired
if he rests on the seat for a long time. Take a polyurethane seat
for a car or motorcycle as an example. Demands with regard to the
manufacture and structure of such a polyurethane seat are manifold,
but the material itself is so uniform in density that, when a man
sits on the seat, the distribution of pressures on the sitting
surface changes from moment to moment, and thus polyurethane foam
may not be suitable according to given functions assigned to the
seat. Manufacture of products of a polyurethane foam is generally
achieved via blow foaming, and thus the product has a uniform
spring property, or is conferred a number of roughly different
spring properties. Therefore, it is difficult for the product of
polyurethane foam to change its spring properties in accordance
with given requirements. The seat of a motor cycle must change its
spring property according to the type of motor cycle, e.g.,
according to whether the motor cycle is for touring, road racing or
motocross, or to the rider's posture during riding. As it is,
because the seat cannot change its spring property according to the
type of motor cycle or to the rider's posture, the rider must put
or lift his weight on or off the seat as needed during racing,
which, when repeated often over a long time, will cause the overall
center of gravity to be elevated and unbalanced.
[0007] Further, it is difficult to recycle polyurethane foams since
they are thermosetting resins. Therefore, polyurethane foams can
only be recycled by crushing them into chips with a crusher, and
bonding the chips into a material called chip foam (ribbon dead
foam), or can only be burned for recovery of thermal energy. The
method of disposal of polyurethane foams includes landfilling and
incineration. However, stable lands cannot be created by using
polyurethane foams since they are low in bulk density and soft, and
hence landfill sites suitable therefor are limited. Polyurethane
foams may be processed into particles or powders to be disposed
which requires, however, extra handling and costs. Further,
incineration of polyurethane foams may generate hydrocyanic acid
gases (hydrocyanic acid) which cause much damage to incinerators,
and have to be eliminated at high costs. As described above, it is
difficult to dispose polyurethane foams in accordance with the
Recycle Act without giving adverse side effects on environments
during and after disposal.
[0008] In addition to above, polyurethane foams have problems as
described below.
[0009] Manufacture of a polyurethane foam mold is achieved by
blowing a foaming material in a die (for example, for three
minutes) and separating the mold from the die. The separation
process is complicated and molding time is long. It is difficult to
clean polyurethane foams. This is because an amine catalyst used
during manufacture is trapped in the foams, causing bad smell. A
polyurethane foam has a heat storage property, and is liable to be
stuffy, and there is a fear that if the polyurethane foam is
exposed to intensive light for a long time, it may start to burn.
Its safety to environments is low.
[0010] Although year 2020 is set to a deadline of abolition of use
of CFCs (chlorofluorocarbons) substitute which is used as a foaming
agent, there is not yet found an alternate agent that is more
excellent in foaming performance than the CFCs substitute. TDI
(tolylene diisocyanate) which is an isocyanate normally used for
producing soft polyurethane foams is a very harmful material and
Notification No. 25 of the Ministry of Labor of Japanese Government
prescribes that TDI should be used at a concentration of 0.005 ppm
or less. In many actual manufacturing sites, thorough control of
TDI is not carried out, causing damage to health of workers.
[0011] The above-mentioned seat cushion pad for an automotive
vehicle disclosed in Japanese Patent No. 2995325 is improved in the
characteristics of the soft polyurethane foam, but still has the
drawbacks of polyurethane foams. In the cushion structure proposed
in the Japanese Patent No. 2548477, it is difficult to be recycled
due to fusing polyester fibers with a high melting point via a
thermoplastic elastomer with a low melting point, resulting in
complicated manufacturing method and high cost for producing.
Although the cushion proposed in Japanese Laid-Open Patent
Publication (Kokai) No. 2000-51011 offers advantages in that it has
excellent air permeability and is cleanable, it suffers from
disadvantages in that it has a low durability, a manufacturing
method thereof is complicated, and a processing cost is remarkably
high. Further, since the rubber adhesive and a crosslinkable
polyurethane are thermoset resins, and the cushion is not of a
single composition, it is difficult to recycle the cushion.
[0012] At present, however, despite that polyurethane foams have
many problems as described above, there is no alternate agent to
replace polyurethane that can be used not less suitably and cheaply
than polyurethane as a cushion material of the seats of automotive
vehicles, motor cycles, bicycles, electric trains, and aircraft,
and of beds.
DISCLOSURE OF INVENTION
[0013] In view of above, an object of the present invention is to
provide a method for producing a cushion material composed of a
resin molded article with a spring structure, that is, a material
suitably used for producing any supports on which one can sit, rest
or mount such as seats of automotive vehicles, motor cycles,
bicycles, electric trains, and aircraft, saddles for horse riding,
chairs, sofas and beds. To put it more specifically, the object of
the invention is to provide a method for producing a molded article
which simplifies molding process, permits the manufacture of a mold
comparatively freely in shape and size, requires a small cost for
production, and readily produces a cushion which satisfies widely
different requirements offered to springy articles such as: being
resistant to sinking and, when a user sits on it, being capable of
dispersing his weight uniformly over the sitting surface so that it
does not fatigue the user even if he sits on it for a long time,
and which is excellent in shock resistance and load capacity.
Particularly, the object of the invention is to provide a method
for producing a molded article which simplifies production
facilities, lowers production cost, improves the precision of
molding, reduces works required for processing, and can provide
finished products in which ends of the product will not
disintegrate of themselves even without deliberately resorting to
trimming or rounding-off after molding.
SUMMARY OF THE INVENTION
[0014] To attain the above objects, the method of this invention
for producing a cushion material composed of a resin molded article
with a spring structure comprises the steps of forming a
three-dimensional structure including voids at a predetermined bulk
density which is obtained by contacting, entwining, and gathering
adjacent ones of random loops or curls of continuous and/or short,
solid and/or hollow filaments made from a thermoplastic resin;
heating the three-dimensional structure placed in a female die
directly and/or via the die to a temperature sufficiently high to
soften the three-dimensional structure; compressing the
three-dimensional structure by bringing a male die in tight contact
with the female die; and hardening the three-dimensional structure
by cooling.
[0015] The method preferably further comprises a step of removing
superfluous ends of the three-dimensional structure protruding into
strokes between the male and female dies using a heat cutter, to
thereby thermally fuse the ends as well as to cut them off.
[0016] The "continuous and/or short filaments" preferably includes
filaments made from general purpose plastics (polyolefins,
polystyrene resins, methacryl resins, poly vinyl chloride, etc.) or
engineering plastics (polyamide, polycarbonate, saturated
polyester, polyacetal, etc.). For example, they are preferably made
from thermoplastic elastomers such as polyethylene (PE
hereinafter), polypropylene (PP hereinafter), and nylon.
[0017] Particularly, the filaments are preferably made from a
mixture obtained by adding a vinyl acetate resin (VAC hereinafter),
ethylene vinyl acetate copolymer (EVA hereinafter), or styrene
butadiene styrene (SBS hereinafter) to a polyolefin resin such as
PE or PP. The mixture ratio of the vinyl acetate content of the
polyolefin resin to VAC or EVA is 70 to 97 wt % to 3 to 30 wt %,
preferably 80 to 90 wt % to 10 to 20 wt %. If the VAC content were
equal to or lower than 3 wt %, the impact resilience of the
three-dimensional structure would be low. On the contrary, if the
VAC content were equal to or higher than 30 wt %, the thermal
characteristics of the structure would be degraded. The mixture
ratio of the polyolefin resin to SBS is 50 to 97 wt % to 3 to 50 wt
%, preferably 70 to 90 wt % to 10 to 30 wt %. The polyolefin resin
may be a regenerated resin.
[0018] "The continuous and/or short filaments" may be solid or
hollow. If the continuous and/or short filaments are hollow, they
are preferable because the air is entrapped in the hollow cavities
of the filaments, and act as a spring which confers a
characteristic spring property to the filaments. The air entrapped
in the hollow cavities of the filaments also prevents the
collapsing tendency of the filaments which would otherwise result
from long and habitual use. The air entrapped in the hollow
cavities of the filaments also preserves the rigidity of the
three-dimensional structure. The hollow cavities may be continuous
with other ones or may be independent of each other. As one
illustrative example, each of single hollow fibers may have hollow
cavities with septa inserted between adjacent cavities. If a
mixture of solid filaments and hollow filaments is used as a
material of the filaments, the mixture ratio of solid filaments to
hollow filaments is preferably solid:hollow=0 to 50:50 to 100.
Further, if hollow filaments are used in a central portion of the
structure, and covered with solid ones, the resulting structure
will give a desirable tactile impression.
[0019] The "solid continuous filaments and/or short filaments"
preferably have a diameter of 0.3 to 3.0 mm, particularly 0.7 to
1.0 mm. If the solid continuous filaments have a diameter equal to
or smaller than 0.3 mm, the filaments would lose resiliency and
fuse to each other so strongly that their void ratio would become
undesirably low. On the contrary, if the solid continuous filaments
have a diameter equal to or larger than 3.0 mm, the filaments would
become so resilient that they would not form loops and curls, nor
fuse together, which would lead to the lowered strength. If the
filaments include hollow filaments, they preferably have a diameter
of 1.0 to 3.0 mm, particularly 1.5 to 2.0 mm. If the void ratio
were equal to or lower than 10%, the hollow filaments would lose
the merit of reducing the weight of the product relative to its
bulk. On the contrary, if the void ratio were equal to or higher
than 80%, the hollow filaments would lose their cushioning
activity.
[0020] The bulk density of the "resin molded article with a spring
structure" may be 0.005 to 0.08 g/cm.sup.3, preferably 0.02 to 0.06
g/cm.sup.3. If the bulk density in question were 0.005 g/cm.sup.3
or lower, the article would have a reduced strength. On the
contrary, if the bulk density in question were 0.08 g/cm.sup.3 or
higher, the filaments would lose the merit of reducing the weight
of the article with respect to its bulk. The resin molded article
with a spring structure may have a uniform density throughout its
structure or may have a structure where high density and low
density substructures repeat alternately at certain intervals. In
the latter case, the low density substructure may have a density of
0.005 to 0.03 g/cm.sup.3, preferably 0.008 to 0.03 g/cm.sup.3, most
preferably 0.01 to 0.03 g/cm.sup.3. The high density substructure
may have a density of 0.03 to 0.08 g/cm.sup.3, preferably 0.04 to
0.07 g/cm.sup.3, most preferably 0.05 to 0.06 g/cm.sup.3.
[0021] The void ratio of the "resin molded article with a spring
structure" may be 96 to 99%, preferably 97 to 99%, most preferably
97 to 98%. To maintain elasticity and strength of the structure as
a cushion as well as reduce the weight thereof, the void ratio in
question should be in the range as mentioned above. [void ratio
(%)]=(1-[bulk density]/[density of resin]).times.100
[0022] The "cushion material" is preferably obtained by laminating
multiple resin molded articles with a spring structure into a
layered structure. The cushion material is preferably used as a
material of the seats of automotive vehicles, motor cycles,
bicycles, electric trains and aircraft, saddles for horse riding,
chairs, sofas and beds. The cushion material may be used, in place
of urethane foams, as a material of any supports on which one can
sit, rest or mount regardless of whether they are exposed to
vibrations or not.
[0023] Particularly, when the cushion material is used as a
material of the seat of an automotive vehicle or motor cycle which
is exposed to vigorous vibrations during use, it is preferred
because it readily adapts to various individual requirements (e.g.,
suspension characteristic) of the vehicle because of its thickness
being susceptible to external controls.
[0024] The "female die" is preferably made of concrete. The
concrete die dispenses with the use of a separating agent, and thus
reduces the cost of molding. The "male die" preferably consists of
a product (base) to which the cushion material can be attached.
Then, need for separate preparation of a male die can be safely
avoided, which will allow the molding cost to be reduced, and
precision of molding to be improved. Cooling may consist of
spontaneous cooling or forced cooling. Forced cooling is preferably
based on the use of water.
[0025] The cushion material of the invention is more receptive to
secondary processing than polyurethane, and can respond to needs
from consumers with regard to particular functions more finely than
polyurethane. Molding the cushion material is achieved by
compression molding. Thus, it is possible to provide a product to
match with the body shape of a given user, or in accordance with
the order of a user which will further enhance the advantage of the
product. Moreover, by adjusting the diameter of filaments
constituting a resin molded article with a spring structure,
material of the filaments, and their denier, bulk density and void
ratio, it is possible to allow the resin molded particle to have a
desired spring property. Although individual filaments constituting
the cushion material of the invention are equal in terms of spring
property, they may be conferred different spring properties after
having been differently compressed during compression molding.
Therefore, it is possible to provide a cushion material in which
different portions have different cushioning abilities and thus in
which, when a weight is put thereon, the weight is supported in
different manners according to the sites with which it is put into
contact. Moreover, it is possible by adjusting the stroke of the
male die to allow the mold to have a desired thickness.
[0026] Particularly, the "male die" may be constituted with a base
(which forms an element of the cushion material constituting the
product) to which a resin molded article with a spring structure
can be attached. Then, deliberate preparation of a male die
dedicated for the purpose can be safely dispensed with, which will
lead to the reduced production cost. Moreover, because part of the
product is used as an element (molding part) of the molding
apparatus, precision of molding will be improved. For raising or
lowering the male die, it is preferable to use a pantograph type
framework. As compared with a hydraulic cylinder or pneumatic
cylinder which is used in a conventional apparatus for molding
polyurethane, the framework in question is so simple that it will
contribute to the reduction of production cost as well as to the
simplification of production facilities. The male die is preferably
so constructed as to forbear a load weighing it or more. If the
female die is made of concrete, it will be possible to safely
dispense with the use of a separating agent which would be
otherwise required, as well as to reduce production cost as
compared with molding where metal dies are used for the same
purpose. Moreover, since the molding process itself is simplified,
and time required for molding is contracted, mass production of
cushion materials will become possible. Cooling may consist of
spontaneous cooling or forced cooling. Forced cooling is preferably
based on the use of water.
[0027] Generally speaking, with regard to the resin molded article
with a spring structure as described above, ends of the article
tend to disintegrate after molding, and thus require trimming or
rounding-off subsequent to molding, which may be cumbersome.
However, with the present article with a spring structure, it is
possible to trim ends of the article after compression molding by
cutting and fusion using a heat cutter, and thus to dispense with
the trimming process as above, which reduces superfluous works.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The objects and advantages of the invention will become
apparent from the following detailed description of preferred
embodiments thereof provided in connection with the accompanying
drawings in which:
[0029] FIG. 1 shows a perspective view of a cushion material
attached to a base 4.
[0030] FIGS. 2a and 2b show frontal and rear views of the cushion
material 1 attached to base 4, respectively.
[0031] FIG. 3 shows a lateral view of a motor cycle 10 equipped
with a seat composed of cushion material 1.
[0032] FIGS. 4a and 4b show perspective views of base 4 viewed from
different angles.
[0033] FIG. 5 illustrates a first step of the compression molding
applied to the cushion material 1.
[0034] FIG. 6 illustrates the first step of the compression molding
applied to the cushion material 1 viewed from a different
angle.
[0035] FIG. 7 illustrates a second step of the compression molding
applied to the cushion material 1.
[0036] FIG. 8 illustrates the second step of the compression
molding applied to the cushion material 1 viewed from a different
angle.
[0037] FIG. 9 illustrates a third step of the compression molding
applied to the cushion material 1.
[0038] FIG. 10 illustrates a step for attaching the cushion
material 1 to a base.
[0039] FIG. 11 is a diagram schematically showing steps necessary
for producing a resin molded article 30 having a spring
structure.
[0040] FIG. 12 shows a perspective view of an apparatus for
producing a resin molded article 30 having a spring structure
according to the method of the invention.
[0041] FIG. 13 shows a perspective view of another apparatus for
producing a resin molded article 30 having a spring structure
according to the method of the invention.
[0042] FIG. 14 shows a perspective view of yet another apparatus
for producing a resin molded article 30 having a spring structure
according to the method of the invention.
[0043] FIGS. 15a, 15b and 15c show the cross-sections of other
resin molded articles 30 having a spring structure embodying the
invention.
[0044] FIGS. 16a, 16b and 16c show the cross-sections of yet other
resin molded articles 30 having a spring structure embodying the
invention.
[0045] FIGS. 17a and 17b show rear and perspective views of a
molding die 622, respectively.
[0046] FIGS. 18a, 18b and 18c show the cross-sections of a resin
molded article 30 having a spring structure and of threads 31.
[0047] FIGS. 19a and 19b show the cross-sections of yet another
cushion material 1 embodying the invention.
[0048] FIGS. 20a and 20b show the cross-sections of yet another
cushion material 1 embodying the invention.
[0049] FIG. 21 illustrates another embodiment of compression
molding necessary for molding a cushion material 1.
[0050] FIGS. 22a and 22b illustrate yet another embodiment of
compression molding necessary for molding a cushion material 1.
[0051] FIGS. 23a and 23b illustrate an exemplary compression
molding process applied to a cushion material 1 using a
conventional apparatus.
[0052] FIG. 24 illustrates another exemplary compression molding
process applied to a cushion material 1.
[0053] FIGS. 25a and 25b illustrate yet another exemplary
compression molding process applied to a cushion material 1.
[0054] FIGS. 26a and 26b illustrate yet another exemplary
compression molding process applied to a cushion material 1 using a
conventional apparatuses.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0055] As is obvious from the reference to a perspective view shown
in FIG. 1, and frontal and rear views shown in FIGS. 2a and 2b, the
cushion material 1 is obtained by preparing a thermoplastic resin
(e.g., thermoplastic elastomer) such as a blend obtained by mixing,
for example, a polyolefin resin such as PE, PP, etc., with VAC, EVA
or SBS, and by processing the blend into a resin molded article 30
with a spring structure or a three-dimensional structure, and
subjecting the article or the structure to compression molding.
Explanation of a Resin Molded Article 30 with a Spring
Structure
[0056] Firstly, the resin molded article 30 with a spring structure
will be described.
[0057] The resin molded article 30 with a spring structure used in
this embodiment of the invention is a three-dimensional structure
having voids which is obtained by contacting, entwining, and
gathering adjacent ones of random loops or curls of continuous
and/or short filaments (simply filaments 31 hereinafter) made from
the above-described blend. The filaments exist as plural loops and
curls (see the inset figure A of FIG. 1 which enlarges a part of
interest). In this embodiment, the resin molded article 30 with a
spring structure comprises hollow filaments 31 whose cross-section
31a is shown in the figure (see the inset figure B of FIG. 1 which
enlarges another part of interest).
[0058] In this embodiment, the bulk density of the
three-dimensional structure may be 0.005 to 0.03 g/cm.sup.3,
preferably 0.008 to 0.03 g/cm.sup.3, most preferably 0.01 to 0.03
g/cm.sup.3. The void ratio of the three-dimensional structure may
be 96 to 99%, preferably 97 to 99%, most preferably 97 to 98%.
Explanation of Cushion Material 1
[0059] Next, the cushion material 1 will be described.
[0060] The cushion material 1 is obtained by subjecting the resin
molded article 30 with a spring structure to compression molding.
The cushion material of this embodiment is mainly used as a
material of the seat of an automotive bicycles (e.g., motor cycles
10).
[0061] The cushion material 1 has a bilayered structure consisting
of two sheet layers (overlying sheet layer 2 and underlying sheet
layer 3). The two sheets may have the same spring property, or
different spring properties. The two sheet layers are preferably
bonded to each other with an adhesive agent or double-faced tape.
It is possible to cause the two sheet layers or different portions
of each sheet layer to have different spring properties by
appropriately adjusting the density of resin molded article 30 with
a spring structure, its material, and/or the diameter of filaments
of the article constituting the sheet layers. In detail, the two
layers preferably have different spring properties such that, for
example, the overlying sheet layer gives a rigid feel while the
underlying sheet layer a soft feel.
[0062] According to this particular embodiment, the overlying sheet
layer 2 is less rigid or softer than the underlying sheet layer 3.
This is because the underlying sheet 3 must be fixed to a base 4
while the overlying sheet 2 must directly receive the buttock of a
rider during riding. The overlying sheet 2 preferably has the bulge
of its upper surface modified to fit to the shape of rider's
buttock when the rider takes a riding posture on the seat. On the
other hand, since the underlying sheet layer 3 is fixed to base 4,
it must be harder than the overlying sheet layer 2. The cushion
material is preferably constructed such that its shape is
maintained via the hardness of the underlying sheet layer 3.
[0063] The cushion material 1 has a characteristic suspension
property due to the underlying sheet layer 3. A conventional seat
of an automotive bicycles using urethane foam usually receives a
strong counter force (kick back) from the road surface after it
exerts a downward spring move towards the road. To absorb such a
counter force, the conventional seat of a motorcycle made from a
polyurethane foam often contains coil springs intimately bonded to
the polyurethane foam. However, according to this embodiment, the
seat has a bilayered structure: the softer overlying sheet layer 2
is for receiving human weight while the harder underlying sheet
layer 3 is for absorbing downward spring properties. This
structural feature can dispense with the use of coil springs.
Accordingly, the seat of this embodiment is advantageous in weight
and structure, in simplicity and in that it does not require the
introduction of any special facilities for absorbing downward
spring properties. Moreover, the bulk of the seat is comparatively
low, and thus the center of gravity lowers, which helps to
stabilize the rider's posture during riding. Further, it is
possible by adjusting the stroke of the male die to allow the
cushion material 1 to have desired thickness for its different
portions. Thus, it is possible by adjusting the stroke of the male
die to produce cushion materials different in size, shape and
profile to meet different suspension requirements.
[0064] Since the cushion material 1 is composed of a resin molded
article 30 with a spring structure, its air permeability is so high
that it naturally rejects the sojourn of moisture. Moreover, if
cooled or warmed air transmitted through a duct from an air
conditioner is permitted to pass through the cushion material of
the seat of motorcycle 10, the rider can cool or warm his body
during riding. If the same equipment is incorporated in the seat of
an automotive vehicle, the vehicle can enjoy the state-of-the art
function without resorting to any special facilities for the
purpose.
[0065] The shape of the cushion material 1 having a bilayered
structure comprising the overlying sheet layer 2 and underlying
sheet layer 3 is not limited to the one described above with
reference to figures, but may take any shape as desired according
to given applications. For example, the cushion material 1 may have
a single-layered structure. Conversely, the cushion material may
have a multiple-layered structure comprising two or more layers.
With regard to a cushion material having a multiple-layered
structure, at least one underlying layer may be made of a synthetic
rubber but at least one of the layers (preferably overlying layers)
is preferably made of a thermoplastic resin. The shape of a bulge
is not limited to the one described above. The shape, profile and
size of a cushion material may be appropriately modified so as to
finely meet given requirements such as product standards,
functions, and individual customers' needs.
[0066] It is preferable to place a kilt cushion material composed
of a resin molded article with a spring structure (stitched
manually or with a sewing machine) over another cushion material
having a multiple-layered structure (e.g., the overlying sheet
layer 2 of cushion material 1), and to use the assembly as a
top-sheet of the seat (not illustrated here). In this case, it is
possible to confer such subtly undulating bulge that can never be
observed in the seat prepared based on conventional molding, that
is, to appropriately modify the shape, profile and size of cushion
materials so as to provide seats that can finely meet given
requirements such as product standards, functions, and individual
customers' needs. Thus, it is possible to modify the size, shape
and profile of the seat of motorcycle in accordance with the type
of the motorcycle, or the body form of the rider. To put it more
specifically, if the seat is for a motorcycle 10 or an automotive
vehicle whose user (e.g., professional driver) is strict about
driving posture, it is possible to modify the size, shape and
profile of the seat in accordance with requirements from the user
so that the seat can exactly fit to his driving posture and
performance, which will confer the seat an additional merit.
[0067] Both the overlying sheet layer 2 and underlying sheet layer
3 have shapes corresponding with that of base 4. As is obvious from
inspection of the perspective views of FIGS. 4a and 4b, the base 4
forms a basement of the seat of motorcycle 10. The base 4 has a
stopper portion 4a on its frontal side and bulge 4b on its rear
side. The bulge 4b has, on its bottom surface, brackets 4c with
which the seat is fixed to the frame of motorcycle 10. The base 4
has several (e.g., six) cushions 4d made from rubber attached to
its bottom surface. Otherwise, many grooves and holes are formed as
shown in the figures.
Apparatus for Producing a Cushion Material 1 and Method
Therefor
[0068] Next, an apparatus for producing a cushion material 1
embodying the invention and method therefore will be described with
reference to FIGS. 5 to 10. A method for producing a resin molded
article 30 with a spring structure will be described later.
1) Feeding Step
[0069] FIG. 5 shows a lateral view of a system for producing a
cushion material 1 which is introduced for illustrating a first
stage of compression molding required for molding the cushion
material. FIG. 6 shows a frontal view of the same system for
illustrating the first stage of compression molding. As seen from
inspection of the illustration of FIG. 5 or 6, one or more resin
molded articles 30 with a spring structure is placed in a female
die 11 made of concrete (simply female die 11 hereinafter). At
least two resin molded articles 30 may have the same spring
property or different spring properties from each other. As
described earlier, each resin molded article 30 is a
three-dimensional structure having voids obtained by contacting,
entwining, and gathering adjacent ones of random loops or curls of
filaments 31 (see the inset figure C of FIG. 5 which enlarges a
part of interest).
[0070] According to this production method, it is necessary to heat
the resin molded articles 30 with a spring structure at a
temperature exceeding the softening point of a resin constituting
the filaments 31. To achieve this, hot water (preferably having a
temperature of 70.degree. C. or higher) from a hot water feeder 13
is allowed to enter into the cavity 12 formed within the male die
11, to thereby heat the resin molded articles 30 with a spring
structure to soften them. Feeding hot water into the cavity of
female die 11 is for permitting the hot water to penetrate the
resin molded articles 30 and to heat them from inside of the female
die 11. Alternatively, the female die 11 itself may be heated with
a heater. In this case, a heat conductor (e.g., heater) is
preferably embedded in the concrete walls of female die 11.
Preferably, the female die 11 are covered with a thermally
insulating material (e.g., with a box made of wood or of a foaming
resin). When it is necessary to heat the air (including the air in
the hollow cavities, if the filaments are hollow) contained around
filaments 31 constituting the resin molded articles 30 with a
spring structure, preferably extra heat from the heater embedded in
the concrete walls of female die 11 is used. The hot water feeder
13 may be substituted for a steam feeder 17 or the like. When a
steam feeder 17 is used, steam inlets are formed on the wall of the
female die 11 so that steam can enter the cavity 12 within the die
via the inlets. Steam is preferably injected into the die when
closure of dies occurs to thereby heat the mold. This mode of
heating is preferred because it allows the uniform transmission of
a high temperature to the mold. When molding requires
pressurization as well as heating, steam heating is preferred
because steam not only heats the mold but also can apply a pressure
on it. Steam heating is also effective for pressurizing a mold
while heating it, when the mold has such a complicated structure as
to reject uniform pressurization when mechanically pressurized.
[0071] Preparation of the female die 11 may be achieved, for
example, as follows. A framework is prepared from an appropriate
material such as gypsum or the like. The framework is reversed and
fixed on a horizontal plate, a separating agent is applied on the
framework or the plate, a concrete powder is kneaded with water to
give a paste, the paste is poured into the space enclosed by the
framework, and the framework is removed to give a concrete die.
Namely, after the concrete paste has hardened, the framework is
reversed again to the original position, and the framework and
horizontal plate are removed to isolate a concrete female die 11.
During the preparation process, it is possible by forming a space
below the horizontal plate attached to the framework, and by
adjusting the height of the space to alter the strength, rigidity
and thickness of concrete as desired. For example, to increase the
thickness of concrete, it is only necessary to lower the fixing
position of the plate. Since concrete is highly moldable, and
easily produces a desired mold when poured into a framework to be
hardened, the production cost of the concrete female die 1 is
comparatively low ( 1/50 to 1/100 times as low as the production
cost required for a similar die prepared via a conventional die).
Concrete further allows the production of female molds 11 having
complicated shapes, and mass production of the same mold with
improved precision. For example, for molding molds of the same
size, the same master framework can be used repeatedly. Further,
since the concrete die comes into close contact with a melt, only
tight closure of mating dies allows the formation of a mold each of
which external faces is polished as smooth as an abraded surface.
If the framework has a negative relief pattern on its inner wall,
the pattern will be transferred to the corresponding outer wall of
a mold. Or, if mating dies are closed with a vinyl sheet placed in
between, the external surfaces of the mold will have an impression
reminiscent of the texture or surface print of the vinyl sheet.
Furthermore, since the female die 11 is made of concrete, it can
safely withstand a high pressure that is applied while a cushion
material 1 is molded, and its durability is so high as to withstand
repeated usage as many as several tens thousand times moldings. The
weight of the female die 11 is preferably 50 to 100 kg.
[0072] The male die 14 is constituted with a base 4 and male
platform 14a (see FIGS. 4a and 4b). The male die 14 is fixed at
several points via fixtures to the distal end of a pantograph jack
15. The male die 14, being activated by the pantograph jack 15,
mates with the female die 11 to thereby apply a pressure from
upward onto the resin molded article 30 with a spring structure
placed in the cavity 12 of the female die 11. The male die 14 is
preferably so sturdy as to withstand a pressure of 10 t or higher.
In this embodiment, a plurality of (e.g., three) pantograph jacks
15 are attached to one male die 14. This is for increasing a
pressure applied to the mold, and for dispersing the applied
pressure over plural (e.g., three) sites. The pantograph jack 15
may be operated manually, or may be automatically operated being
connected to a motor 15a as needed. The proximal end of pantograph
jack 15 is fixed to a roof 18, and the roof 18 is supported by
pillars 19 on the top edges of the female die 11. Introduction of
the pantograph jack 15 allows the structure of the system to be
simplified which leads to the reduction of cost. However, the
pantograph jack 15 may be substituted for a hydraulic or pneumatic
cylinders or the like.
[0073] The male die 14 preferably includes, as its element, a base
4 which also serves as an element of the product. The base 4 is
attached to the male die platform 14a with the bottom surface of
the former facing to the lower surface of the latter. The upper
surface of the male die platform 14a is fixed via joining members
to the pantograph jack 15. Since part of the product (base 4) also
comprises as an element (male die 14) of the molding apparatus, it
is only necessary to prepare a female die 11 and separate
preparation of a male die 14 can be safely dispensed with. With the
conventional system for molding polyurethane foams, it is necessary
to prepare male and female dies separately. However, with the
system operating according to the method of the invention, since
part of the product serves as an element of male die, preparation
of a platen and punch is not needed, which leads to reduced costs
and improved precision of molding.
2) Die Closing Process
[0074] FIG. 7 shows a lateral view of the system for producing a
cushion material 1 which is introduced for illustrating a second
stage of compression molding required for molding the cushion
material, while FIG. 8 shows a frontal sectional view of the same
system for illustrating the second stage of the compression
molding. As seen from inspection of the illustrations shown in
FIGS. 7 and 8, the pantograph jack 15 is activated to push the male
die 14 (which is acted by the base 4) downward as indicated by the
arrows in FIGS. 7 and 8, to compress the mold. In this particular
embodiment, the female die 11 is so adjusted as to allow the male
die to enter into the cavity 12 to a deep level. Namely, the female
die 11 can be adjusted so as to allow the male die 14 to enter into
the cavity to a desired level. Since mating of the two dies occurs
with a more or less redundancy, it is possible to alter the
thickness of cushion material in accordance with a given
requirement by adjusting the stroke between the two mating dies.
Therefore, with the same pair of mating dies, it is possible to
produce cushion materials having various thickness. Needless to
say, it is also possible to alter the density of cushion materials.
As described above, with the same pair of mating dies, it is
possible to produce various cushion materials varying in density,
spring property and rigidity by simply adjusting the stroke between
the two mating dies as appropriate.
[0075] With this system it is possible to freely adjust the
thickness of a cushion material 1 by adjusting the stroke between
the two mating dies. If it is required to produce a thin cushion
material 1, it is only necessary to reduce the stroke between the
two mating dies to a desired small distance. Conversely, if it is
required to produce a thick cushion material 1, it is only
necessary to increase the stroke between the two mating dies to a
desired large distance. Namely, with this system it is possible to
freely adjust the thickness of a cushion material 1. It is also
possible to freely adjust the density, spring property and rigidity
of a cushion material. If the tapered angle of the inner lateral
walls of the female die 11 (inner lateral walls of the female die
illustrated are substantially perpendicular to the base) is made
smaller as needed than illustrated, it is possible to produce a
cushion material whose profile has a desired slope angle. The
desired slope angle may include, for example, 1/50 to 1/400 (e.g.,
1/200). The slope angle may be inwardly or outwardly directed. If
the female die 11 has a too large inward slope angle, it will be
difficult to adjust the stroke between the two mating dies to a
desired distance. Thus, it is possible using the same pair of
mating dies to produce various cushion materials 1 in accordance
with given requirements. Particularly, it is possible to produce
the same cushion materials 1 having various desired thickness. For
example, it is possible to produce a cushion material in accordance
with a given personal order, that is, to produce cushion materials
finely meeting personal needs of individual customers. With regard
to the parts of the seat facing the inner thighs of rider, it is
preferred to prepare the parts such that they have an enhanced
density and rigidity at the cost of spring property. This improves
the cushioning property and durability of the seat.
[0076] Generally, the outline of the seat is determined by the
rider's riding posture, and is more or less constant. However, the
thickness of the seat may vary depending on the type (required
suspension property) of the motorcycle. Thus, it is necessary to
adjust the thickness of the cushion material 1 according to the
type of the motorcycle. When a polyurethane foam is used as a
cushion material, it is processed into a mold while foaming. Thus,
the mold undergoes uniform expansion during molding as long as the
same dies are used. Thus, it is necessary to prepare multiple pairs
of mating dies if it is required to produce cushion materials
having different densities and thickness. According to the
production method of this invention, the problems encountered with
the conventional method using polyurethane foams can be safely
avoided.
3) Trimming Process
[0077] FIG. 9 shows a flat view of the system for producing a
cushion material 1 which is introduced for illustrating a third
stage of compression molding required for molding the cushion
material. As seen from inspection of the illustration shown in FIG.
9, after the mating dies are kept closed for a certain
predetermined period, a heat cutter 16 is moved along the edges of
the male die 14 to remove burrs 32 protruded from the edges of the
male die 14 (see the inset figure of FIG. 9 which enlarges a part
of interest) by cutting out those burrs as well as fusing the
filament ends of the burrs. According to the conventional method,
the mold has its edges trimmed after molding to fit to a desired
size, which complicates works involved in trimming. However, with
the method of the invention, the mold is easily trimmed.
Particularly, since trimming is introduced at a stage subsequent to
molding, it is possible to fuse the open ends of filaments of the
burrs to prevent their disintegration during use, to dispense with
the scaling step where the mold is tested for its size being as
designed, and to simplify testing procedures subsequent to
molding.
4) Mold Separating Process
[0078] Cooled water is poured in the cavity 12 of female die 11 to
harden the resin molded article 30 with a spring structure. The
water is poured abruptly at one time instead of being slowly poured
little by little, which leads to the reduction of time required for
hardening. After enough time has passed for the mold to harden, the
mold is separated from the dies. Whether a given mold hardens or
not is determined by slightly relaxing the pantograph jack 15 to
see whether there is any spring-back from the mold. If it is found
that there is no spring-back from the mold, the mold sufficiently
hardens. Then, cycles of alternate heating and cooling the female
die 11 and/or resin molded article are repeated. If a mold is
composed of hollow filaments, it is possible to prevent 30 from
occurring spring-back by keeping a thermally equilibrated condition
in consideration of the air masses kept in the hollow cavities of
filaments.
[0079] When the female die 11 is made of concrete, the resin, even
if it is melted, will not adhere to the inner walls of the die
which dispenses with the use of a separating agent. With a molding
apparatus incorporating conventional dies, the temperature rises so
sharply during molding that the resin melt readily adheres to the
inner walls of dies. To meet this drawback, when a polyurethane
foam is molded, it is absolutely necessary to use a separating
agent which may require extra work and time. When the mating dies
are made of concrete, the mold contacts so intimately with the
walls of dies that it is possible to mass-produce copies having an
exactly similar size and shape, even though the shape is
complicated.
5) Finishing Process
[0080] As shown in FIG. 10 which illustrates how a cushion material
1 is attached to a base, an overlying sheet 2 and underlying sheet
3 both prepared as described above are placed one over another, and
the assembly is laid over a base 4. A heat-shaped vinyl leather
sheet 5 is laid over the assembly, and fixed to the base 4 with a
stapler. Alternatively, fixation of the vinyl leather sheet 5 to
the base 4 may be achieved via an adhesive tape. If the underlying
sheet 3 is allowed, during molding, to have indents (or recesses)
which engage with corresponding recesses (or indents) formed on the
base 4, it is possible for the assembly to be safely fixed to the
base without requiring the use of a stapler or double-faced tape.
Layering of the overlying sheet 2 on the underlying sheet 3 may be
stabilized by inserting a bonding agent or adhesive tape between
the two opposite surfaces. Alternatively, the two sheets may have
indents or recesses on their opposing surfaces which will engage
with each other when the two sheets are assembled. Then, assemblage
of the two sheets does not require the use of a bonding agent or
adhesive tape. It should noted, however, that assemblage of the
overlying sheet 2, underlying sheet 3 and base 4 may not require
any deliberate fixation procedure, as far as they are covered with
a vinyl leather sheet 5 in the finishing process.
Method for Producing a Resin Molded Article 30 with a Spring
Structure
[0081] An exemplary method for producing a resin molded article 30
with a spring structure as described above will be described.
[0082] As shown in the diagrams of FIG. 11, according to the method
of this embodiment for producing resin molded articles 30 with a
spring structure, preferably, a polyolefin resin such as PE, PP or
the like and another resin such as VAC, EVA or SBS are fed, in
appropriate amounts, via a supplier such as a tumbler, feeder or
metering feeder, and the start resin is dry-blended, mixed, or
dissolved in a solvent, kneaded and fragmented into pellets. The
powdery mixture or pellets are transferred to a hopper 21 of an
extruder 20.
[0083] To be more specific, start resins, e.g., PP and SBS are
mixed with a tumbler (KR mixer, Kato Scientific Instruments Co.) at
40 rpm for 15 minutes.
[0084] Next, as seen from the perspective view of FIG. 12, a
mixture comprising the start resins is poured via a hopper 21 to a
uni-axial (axis diameter being 65 m) extruder 20. The mixture is
melted at a predetermined temperature (e.g., 200 to 260.degree.
C.), and the melt is kneaded and subjected to melt-extrusion at a
predetermined speed through a plurality of nozzles, taken off by a
winder 23 which will be described later, and formed into solid
and/or hollow continuous filaments 31 having a predetermined
diameter (e.g., 600 to 90,000 deniers, preferably 3,000 to 30,000
deniers, more preferably 6,000 to 10,000 deniers). The filaments 31
in a fused state are caused to form loops having a diameter of 1 to
10 mm, preferably 1 to 5 mm, and are taken off by the winder within
a (water) bath 25 while bringing adjacent ones of the filaments
into contact with each other within the water to be entwined
forming random loops. The contacted and entwined portions of the
filaments are at least partially fused and bonded to one another.
The filaments 31 may comprise solid filaments and hollow filaments
at a predetermined ratio.
[0085] The thickness and bulk density of the three-dimensional
structure or a mass of random loops may be determined as
appropriate by adjusting the stroke between take up rolls 24, 24 of
the winder 23 in the bath 25. The three-dimensional structure
(e.g., 10 to 200 mm in thickness and 2,000 mm in width) obtained by
processing filaments 31 so as to form a mass of random curls or
loops, and hardening them in water, is applied to another pair of
take-up rolls 26, 26 to produce a resin molded article 30 with a
spring structure.
[0086] When filaments 31 which have been formed into loops in water
are taken off by the winder 23, the cushion property of the
resulting three-dimensional structure may be altered as appropriate
by adjusting the take off speed of the winder 23. The
three-dimensional structure, when it is required to have a
comparatively high bulk density, should have a bulk density of 0.03
to 0.08 g/cm.sup.3, preferably 0.04 to 0.07 g/cm.sup.3, most
preferably 0.05 to 0.06 g/cm.sup.3. The three-dimensional
structure, when it is required to have a comparatively low void
ratio, should have a void ratio of 91 to 97%, preferably 92 to 96%,
most preferably 93 to 94%.
[0087] In taking off the filaments, the take-off speed of the
winder 23 is adjusted to a low take-off speed at intervals of e.g.,
3 to 5 m by e.g., reducing the take-off speed of take up rolls 24,
24 to a low predetermined level at certain predetermined regular
intervals. Then, it is possible to obtain a resin molded article 30
with a spring structure comprising a series of alternate
high-density portions and low-density portions repeating at regular
intervals (e.g., 30 to 50 cm) in a longitudinal direction, the
high-density portions being formed when filaments are taken off at
a low take-off speed while the low-density portions being formed
when filaments are taken off at a high take-off speed.
[0088] As seen from the frontal view of FIG. 13, if it is expected
that a three-dimensional structure such as a resin molded article
30 with a spring structure will hardly be bent by the take-up rolls
24, 24, it is possible to adjust the take-off speed of the winder
as above to produce a three-dimensional structure comprising a
series of high-density portions and low-density portions, and to
adjust the winder system such that the three-dimensional structure
can be bent at their low-density portions. The resin molded article
30 with a spring structure obtained via the above-described
processes are cut with a cutting device 27 into pieces having a
desired length. The bath 25 is equipped with inlet and outlet
valves (not illustrated here).
[0089] As seen from the frontal view of another apparatus shown in
FIG. 14 where a cutting device 127 is placed in a water bath 125,
the cutting device 127 is put below a winder 123, and a transport
device 128 comprising a conveyor carrying multiple joining spikes
on its surface is placed in the water bath 125 opposite to the
winder. The conveyor carries spring structure pieces obtained by
cutting a three-dimensional structure at predetermined sites by
piecing joining spikes into the pieces and thereby capturing them
on its surface. The elements corresponding with those of the
foregoing embodiment are represented by similar numerals with,
however, 1 being attached to the third place of the numerals.
[0090] By a method as described above, a resin molded article 30
having a spring structure is obtained which has, for instance, a
bulk density of 0.03 g/cm.sup.3 and thickness of 50 mm. The
three-dimensional structure can be manufactured by using
sub-structures which include one type of property or a combination
of a plurality of types of properties different from each other.
For the details of how resin molded articles 30 with a spring
structure are actually produced by the aforementioned method, and
results of the tests performed on them, the readers are referred to
EP 00-1-182-826AI and others which were published by the present
Inventors.
Other Embodiments of Resin Molded Articles 30 with a Spring
Structure
[0091] Resin molded articles 30 with a spring structure
representing embodiments other than the foregoing ones will be
described below. Their molding is based on the viscosity of start
resins.
[0092] During molding of a resin molded article 30 with a spring
structure mentioned below, it is possible to obtain a
three-dimensional structure which comprise portions different in
cushion property by adjusting the take-off speed and heating
temperature. For example, it is possible to obtain a resin molded
article 130 with a spring structure as shown in FIG. 15a where the
cushion property is weakened gradually or at predetermined regular
intervals as a testing probe advances from the periphery to the
core. In this particular example, the periphery is constituted with
a hard portion 130a while the core with a soft portion 130b. This
distribution of cushion property may be reversed as seen from a
resin molded article 230 with a spring structure shown in FIG. 15b
where the core is constituted with a hard portion 230a while the
periphery with a soft portion 230b. It is also possible to obtain a
resin molded article with a spring structure where spots having a
different cushion property (for example, two spots) are dispersed
in the article as seen from the one 330 shown in FIG. 15c.
[0093] A resin molded article with a spring structure like the one
130 is suitable as a cushion material of the seat of a motorcycle
10. Since the cushion material 1 has hard lateral surfaces, they
adequately fit to the medial bulges of the rider's thighs when the
rider mounts on the seat and takes a riding posture, which leads to
stable driving. A resin molded article with a spring structure like
the one 230 is suitable as a material of a helmet. A single
three-dimensional structure of which the surface (contacts with the
scalp) is soft while the core is rigid enables the production of
caps (sun hats and helmets) which will not disturb the hair style.
Such a cap is preferable because it prevents the penetration of sun
beams but permits excellent air permeability.
[0094] The cushion material of a seat may achieve its assigned
function as long as it has a sufficiently rigid external surface,
depending on the weight applied on the seat and bending it
undergoes when loaded with the weight. In such a case, it is
possible to obtain a resin molded article with a spring structure
by preparing plural thin three-dimensional structures each having a
different density, and laminating them in an appropriate
combination into a single layered structure, instead of preparing a
single three-dimensional structure which comprises portions having
different densities. This method permits the amount of resins used
for preparing a spring structure to be saved, and improves
productivity. For example, it is possible to obtain a resin molded
article with a spring structure 430 shown in FIG. 16a, by preparing
a three-dimensional structure 430a, placing another structure 430b
having a lower bulk density below it, and placing a second
structure 430c having a yet lower bulk density below the former,
and bonding the three structures into a single layered
structure.
[0095] It is also possible to obtain a resin molded article 30 with
a spring structure 530 shown in FIG. 16b which is partially
reinforced with cavities 530a (partition blocks) which are formed
in the structure by heating the spots to melt away filaments there.
Formation of cavities 530 may be achieved prior to or subsequent to
compression molding. It is also possible to obtain a resin molded
article 30 with a spring structure as shown in FIG. 16c where each
cavity includes a clamp 530b like a metal brace. The clamp 530b may
be inserted into the cavity prior to or subsequent to compression
molding.
[0096] The diameter of filaments 31 constituting a resin molded
article 30 with a spring structure is not necessarily uniform. Even
if a single cushion material is used as a seat, the weight imposed
on a given portion differs depending on which part of the seat the
portion occupies. Enhancing the rigidity of a given portion can be
achieved by altering the bulk density of that portion as well as by
modifying the diameter and/or hardness of filaments constituting
the portion. For example, it is preferable to distribute thick
and/or rigid filaments to a portion which comes into contact with
the rider's buttock and sustains a large part of his weight during
riding.
[0097] To produce a spring structure where one portion (e.g.,
central portion) comprises more thick filaments than the remaining
portions, the molding die 622 has nozzles prepared as shown in FIG.
17a such that nozzles 622a corresponding to the central portion
have a larger diameter than the remaining nozzles 622b. If this
molding die 622 is used, thick filaments 631 are extruded from its
central portion together with normal thin filaments 31 extruded
from the remaining portions as shown in FIG. 17b. It is possible to
obtain a spring structure where the rigidity is altered in a
complicated manner, by using such a molding die as described
above.
[0098] It is also possible to obtain a cushion material which
comprises filaments having the same thickness and bulk density with
those of a comparable structure but is softer or harder than the
comparable structure, by employing a filament material different
from what is used in the comparable structure. For example, if the
cushion material 1 is used as the seat of a motorcycle 10, it is
possible to employ a different filament material in accordance with
the weight of a user, which will increase the marketing value of
the seat.
[0099] It is also possible to entwine filaments of a spring
structure with natural fibers or metal wires to thereby produce a
complex spring structure. By so modifying the filaments of a spring
structure, it is possible to improve, for example, the thermal
resistance, collapsing tendency under prolonged use, and tensile
strength of filaments, that is, weak points inherent to synthetic
resin filaments. For example, it is preferable to entwine filaments
731 with plural metal wires 733 as represented in a resin molded
article 730 with a spring structure shown in FIG. 18a. It is also
preferable to combine hollow filaments 731 with metal wires by not
only entwining the former with the latter, but inserting the latter
through the cavity of the former as shown in a sectional view of a
combined filament of FIGS. 18b and 18c.
Cushion Materials 1 Representing Other Embodiments
[0100] When a female die 11 and male die 14 are closed to compress
a mold to produce a resin molded article 30 with a spring
structure, it is possible to alter the heating temperature in a
stepwise manner to thereby produce a spring structure in which the
rigidity changes from one portion to another. For example, it is
possible to produce a cushion material 101 as shown in FIG. 19a
where a lower portion 101a (plate-like portion) is rigid while an
upper portion 101b is soft. The edges 101c are preferably heated to
be formed into rigid plate-like portions. For example, edge
portions 101c where filament ends are curled by heating are
preferably processed to take a plate-like form during trimming. The
edge portions 101 can snugly mesh with the corresponding edges of a
base 4. Preferably, prior to assemblage, the edge portions 101c are
expanded, and allowed to return by spring property, to thereby mesh
with the corresponding edges of the base. This arrangement allows
the cushion material to be attached to the base without requiring
the use of a stapler, or to be detached from the latter.
[0101] When a female die 11 and male die 14 are closed to compress
a mold to produce a resin molded article 30 with a spring
structure, the female die 11 may be hotly burnt so as to raise the
temperature of the die to such a high level as to melt the surface
of a mold which, when hardened, forms a hard skin covering the mold
(epidermis molding). With this method, it is possible to melt and
harden only the superficial skin 201a of a mold or resin molded
article 30 with a spring structure as seen from a cushion material
201 of FIG. 19b, which will dispense with later coating (e.g.,
coating with a vinyl leather 5). This method is also applicable for
molding an instrument panel using a resin as a material. Namely,
according to this method, it is possible to not only prepare a mold
but also form a hard superficial skin around the mold.
Particularly, if a cushion material 1 must be water-proof or
insoluble to solvents, or must have a protective coating, the
epidermis molding based on hot burning is preferably employed to
form the superficial skin 201a.
[0102] Since the cushion material 1 constituted with a resin molded
article 30 with a spring structure of this embodiment is highly
air-permeable, it is more preferable depending on given
applications to dispense with the use of a vinyl leather 5 than to
cover the cushion material 1 with the leather. If the use of a
vinyl leather is omitted, a resin molded article 30 with a spring
structure is preferably covered with a net 306 as seen from the
cushion materials 301 shown in FIGS. 20a and 20b. The net 306 may
be applied over the cushion material 301 after compression molding.
The net 306 is preferably made of a water-repellent material (e.g.,
plastics). Then, the net 306 can maintain its excellent air
permeability, and thus the seat is conveniently used even when the
area is humid or the time is a wet season. Particularly such a seat
is suitably used when incorporated in a buggy which usually runs on
a sandy land. The net 306 prevents the disintegration of a cushion
material 301 so effectively that it improves the durability of the
seat. The mesh density of the net 306 is not limited to the one
shown in the figure, but may be set to any desired level. A vinyl
leather sheet 5 may be applied over the net-covered cushion
material. This is because, when the seat is incorporated in an
electric train and is damaged intentionally, the seat can be
prevented from the entry of foreign objects.
Mating Dies Representing Other Embodiments
[0103] In the above embodiments, the female die 11 is placed
downward while the male die 14 placed upwards, but positioning of
the two dies may be reversed. If the reverse positioning is
adopted, the female die 11 applies its weight on a mold during
molding, and thus compression molding is achieved via pressures
imposed by a compressor as well as via the weight of the female
die. Both the female die 11 and male die 14 are preferably made
from concrete, metal or FRP (fiberglass reinforced plastics). If
the heavier die is placed upward (pressing side) and allowed to
mate with the opposite die placed downward, it is possible to
exploit the weight of the upper die for compression molding. For
example, compression molding may be achieved by placing one die
made from heavier concrete upward, and the other die made from
lighter concrete downward, or by placing one larger die upward and
the other lighter die downward.
[0104] This embodiment incorporates a pantograph jack 15 to quickly
apply a uniform pressure on a mold. However, if compression molding
is achieved exploiting a pressure due to the heavier weight of a
die placed upward, it may be possible to dispense with the use of a
pantograph jack 15. For example, according to a molding system as
shown in FIG. 21, a male die 114 is suspended with balancers 115 or
the like each comprising a spring material, and compression molding
is achieved by allowing the male die 114 to fall into the female
die 111 due to its own weight as indicated by the arrows of the
figure. Alternatively, the male die 214 may be connected via a
hinge 215 to the female die 211 as shown in FIG. 22. The male die
214 is opened to a predetermined angle, a resin melt is poured into
the cavity within the female die 211, the male die is moved as
indicated by the arrow of the figure until it closes the cavity
within the female die 211, and thus compression molding is achieved
by exploiting the weight of the male die 214.
[0105] FIGS. 24 to 26 concern with other embodiments. With the
systems shown in those figures, vertical positioning of the female
die and male die may be reversed. With the systems, the concrete
female die 11 placed upwards serves as a weight during compression
molding. If the apparatus comprises a female die 111 suspended with
balancers 115 made of a spring material, compression molding may be
achieved by allowing the female die 111 to engage with the male die
114 due to its own weight as indicated by the arrows of the figure.
Alternatively, the male die 214 may be connected via a hinge 215 to
the female die 211 as shown in FIG. 22. The male die 214 is opened
to a predetermined angle, the male die is moved as indicated by the
arrows of the figure until it closes the cavity within the female
die, and thus compression molding is achieved by exploiting the
weight of the female die 211 in mating with the male die 214.
[0106] Although it was mentioned above that the female die 11 is
preferably made of concrete, it is possible to utilize a
conventional apparatus adapted for molding polyurethane foams as
profitably as the apparatus of the invention if the dies are
modified such that their trimming margins can be increased, and
accommodate the expansion of a mold as a result of molding, as
shown in FIGS. 26a and 26b. For example, according to a
conventional system, start resins (liquids) are poured into the
cavity, and an upper die 314 and lower die 314 are mated to be
closed and the resins are allowed to foam in the cavity (foaming as
a result of the mixture of two resins). However, the apparatus may
be modified as follows: a resin molded article 30 with a spring
structure is placed in the cavity, the article is compressed by
mating the two dies, and burrs protruded from the mating dies are
removed via pressures generated as a result of intimate closure of
the two mating dies. Then, it will be possible to obtain a cushion
material 1 like the one representing an embodiment of the invention
without resorting to a apparatus which incorporates concrete-made
mating dies. Or, it is preferable to trim a mold with a heat cutter
after the upper die has been removed. The mating dies 311, 314 of a
conventional apparatus may be made from a metal such as iron. The
die is preferably made from concrete or metal, but may be made from
a complex synthetic resin material such as FRP.
[0107] As shown in FIGS. 26a and 26b, it is possible to employ part
(e.g., lower die 311) of a conventional apparatus. For example,
according to a conventional apparatus, start resins (liquids) are
poured into the cavity, and an upper die (not illustrated) and
lower die 311 are mated to be closed and the resins are allowed to
foam in the cavity (foaming as a result of the mixture of two
resins). Instead, a resin molded article 30 with a spring structure
is placed in a apparatus, and it may be compressed by mating a male
die 314 with a lower die 311 equipped with a base 4.
[0108] The temperature of atmosphere or temperature control is
important for compression molding. During molding, start resins
soften and intermingle. However, the mixture does not occur at
molecular levels because the resins do not melt completely. Thus
the air masses entrapped in a mold are the same with those existent
in the start resins. To properly form a mold, it is necessary for
the temperature of the air masses to be equilibrated with the
softening temperature of start resins. Otherwise, if the heightened
temperature is abruptly reduced to a far low level, the air masses
will expand which will cause spring-backs to impair proper molding,
unless mating of the two dies is maintained so as to keep the
equilibrium state.
INDUSTRIAL APPLICABILITY
[0109] As described above, according to the invention, it is
possible to quickly produce a cushion material constituted with a
resin molded article with a spring structure which has desired
resistances to imposed weight and impact. Mass production of such a
cushion material is also possible. Since the production of such
cushion materials is based on compression molding, it is possible
to freely modify the size and shape of individual products. If the
cushion material is expected to be exposed to vertical vibrations,
horizontal vibrations or complex vibrations, it is possible to
confer bulges and recesses on both sides of a cushion material such
that the cushion material can effectively absorb vibrations as much
as possible.
[0110] According to the method of the invention, since burrs are
cut as well as fused with a heat cutter which is moved along the
edges of a male mold during closure of the two mating dies,
trimming is quite easy. Particularly, since trimming is introduced
at this stage of molding, disintegration of open filaments at the
edges is safely prevented, and renewed trimming and scaling
subsequent to molding which would be otherwise required can be
safely dispensed with, which reduces works required for
after-molding treatment.
[0111] Further, since a base to which a resin molded article with a
spring structure is attached also acts as a male die, it is
necessary to prepare only a female die for proper molding which
will lead to reduced production costs. Furthermore, since the
product itself is utilized as an element of the molding apparatus,
precision of molding will be improved.
[0112] Since it is possible using a molding apparatus incorporating
a single pair of mating dies according to the invention to produce
a cushion material in which some portions have a different
thickness from that of other portions. Thus, with a single
apparatus, it is possible to produce various cushion materials
different in size, shape and density in accordance with individual
requirements without resorting to multiple pairs of dies. More
specifically, it is possible, when it is required to provide seats
appropriate for the type of motorcycles, to provide seats whose
thickness varies depending on the type (required suspension
property) of the motorcycle. For example, according to the method
of the invention, it is possible when it is required to provide
thin cushion materials, to adjust the molding apparatus such that
the stroke between the two mating dies becomes thin. Conversely,
when it is required to provide thick cushion materials, it is only
necessary to adjust the molding apparatus such that the stroke
between the two mating dies becomes wide. Thus, it is possible to
produce cushion materials in accordance with given personal orders,
that is, to produce cushion materials finely meeting personal needs
of individual customers.
[0113] Furthermore, according to the method of the invention, it is
possible to readily produce cushion materials different in property
including their thickness by simply adjusting the stroke interval
between the two mating dies and choosing an appropriate material
(e.g., in filament diameter, texture, bulk density and void ratio).
More specifically, according to the method of the invention, it is
possible with a single apparatus to produce various cushion
materials different in size, shape and density in accordance with
individual requirements without resorting to multiple pairs of
dies. For example, it is possible, when it is required to provide
seats appropriate for the type of motorcycles or automotive
vehicles, to provide seats whose thickness varies depending on the
type (required suspension property) of the motorcycle or automotive
vehicle. Further, according to the method of the invention, it is
possible to provide cushion materials in which the distribution of
spring properties and rigidities is adjusted as desired by simply
varying the stroke width between the two mating dies, without
modifying the physical properties of the cushion material itself.
For example, when a cushion material is used as a material of the
seat of a motorcycle or automotive vehicle, it is possible to
modify the cushion property of the cushion material in accordance
with the type of motorcycle (for touring, road racing or motocross)
without resorting to any complicated processes which would
otherwise be required. If the cushion material is used as a
material of the seat of a motorcycle for motocross, it may be
prepared so as to absorb the weight of a rider. Then, the rider can
steer the motorcycle while resting on the seat which will insure
stability during riding.
[0114] If the cushion material comprises two or more layers of
sheets, it is possible to readily alter the properties of the
cushion material by choosing appropriate constitutive resin molded
articles with a spring structure (in terms of, e.g., diameter of
filaments, material, bulk density, void ratio, etc.) or by
adjusting the stroke width between the two mating dies. For
example, combination of spring properties between the overlying
layer and underlying layer can be altered as desired without
resorting to any complicated processes: it is quite easy to combine
overlying and underlying layers having the same spring property, as
well as to combine an overlying layer having a certain rigidity
with an underlying layer having a lower rigidity. It is also
possible to combine overlying layers with underlying layers such
that there is formed a stepwise stroke between adjacent layers to
thereby produce a central ridge.
[0115] Therefore, it is possible to provide seats that can finely
meet given requirements such as product standards, functions, and
individual customers' needs, which will leads to the increased
value of the product. Thus, when the cushion material is used as a
material of the seat of a motorcycle or automotive vehicle, it is
possible to modify the seat in accordance with the type of the
motorcycle or automotive vehicle, or the body form of the rider. To
put it more specifically, if the seat is for a motorcycle or
automotive vehicle whose user (e.g., professional driver) is strict
about driving posture, it is possible to modify the seat in
accordance with requirements from the user so that the seat can
exactly fit to his driving posture and performance. If the cushion
material is used as a material of the seat of a motorcycle for
motocross, it may be prepared so as to absorb the weight of a
rider. Then, the rider can steer the motorcycle while resting on
the seat which will insure stability during riding.
[0116] According to the method of the invention, cushion materials
are more easily produced than polyurethane foams undergoing
secondary processing according to the conventional method. Although
in manufacturing a polyurethane foam, toxic materials such as TDI
and the like are used, a resin molded article of the present
invention can be produced without generating toxic gases and hence
insures good working conditions.
[0117] According to the method of the invention, resins such as PE
or the like may be recycled into edible oil containers of
thermoplastic resins or biodegradable plastic films for
agricultural use with an additional merit added. Cushion materials
made of a resin molded article with a spring structure themselves
may be repeatedly recycled by melting used cushion materials and
submitting the melt again to molding process. The resin molded
article according to the invention is so excellent in recyclability
that it will not act as an undue load to environments even if it
must be disposed of after use. Further, the resin molded article
according to the invention can be manufactured at reduced costs
since recycled resins can be used for producing the same.
[0118] The cushion material of the invention made of a resin molded
article with a spring structure is highly durable and resistant to
collapsing even after prolonged use, has a very small quantity of
local sinking, and does not give a feeling of touching a hard
bottom, and vertical swing. Moreover, the cushion material, when a
user sits on it, uniformly receives the weight of the user on a
whole region in contact with the cushion structure. Hence, the
cushion material causes less fatigue of the user than a
polyurethane foam-made cushion, and makes the user feel more
relaxed. Thus, the cushion material of the invention can give a
characteristic relaxed feeling to the user that can hardly be
obtained from a polyurethane foam-made cushion.
[0119] The cushion material of the invention made of a resin molded
article with a spring structure has such an excellent spring
property that, when it is used as a material of the seat of an
automotive vehicle or motorcycle, it will dispense with the use of
coil springs which have been installed beneath the conventional
seat of an automotive vehicle or motorcycle to absorb kick-backs
from the road surface which would be otherwise a nuisance to the
driver. This simplifies the structure of the seat, and lowers the
center of gravity, which helps to stabilize the vehicle or
motorcycle during running.
[0120] Since the resin molded article of the invention has a
structure having completely continuous voids, it is so excellent in
air permeability that it does not keep extra moisture. if cooled or
warmed air transmitted through a duct from an air conditioner is
permitted to pass through the cushion material of the seat of
motorcycle, the rider can cool or warm his body during riding.
Since the cushion material is resistant to water and will not
degenerate when soaked with water, it may be profitably used as a
material of the seat of a motorcycle. The cushion material may be
washed with water, and will readily dry even when washed with
water.
[0121] As described above, the method of the invention for
producing a cushion material composed of a resin molded article
having a spring structure is suitably used for providing a cushion
material composed of a resin molded article with a spring
structure, that is, a material suitably used as a supportive
element of any supports on which one can sit, rest or mount such as
seats of automotive vehicles, motor cycles, bicycles, electric
trains, and aircraft, saddles for horse riding, chairs, sofas and
beds, regardless of whether the seat is exposed to vibrations or
not as a substitute for a conventional polyurethane foam-made
cushion material.
[0122] If the cushion material is used as a supportive element of a
seat which is expected to receive no vibrations during use, it is
only necessary to subject one surface of the cushion material to
compression molding. On the contrary, if the cushion material is
used as a supportive element of a seat which is expected to receive
vigorous vibrations during use, for example, the seat of an
automotive vehicle or motorcycle, it is preferable to overlap two
or more cushion materials each comprising kilted resin molded
article with a spring structure.
[0123] If the molding apparatus uses, for compression molding, a
pantograph jack instead of a hydraulic unit, the apparatus can have
a simpler structure which will reduce production costs. Moreover,
with this apparatus, it is easier to adjust the stroke width
between mating dies.
[0124] The embodiments of the present invention are not limited to
those described above, but may permit many variations and
modifications within the technical scope of the invention. Also,
since certain changes may be made in the above construction without
departing from the scope of the invention, it is intended that any
variations of and equivalents to the foregoing embodiments shall be
interpreted as included in the technical scope of the
invention.
[0125] Thus, the broadest claims that follow are not directed to a
machine that is configuration a specific way. Instead, said
broadest claims are intended to protect the heart or essence of
this breakthrough invention. This invention is clearly new and
useful. Moreover, it was not obvious to those of ordinary skill in
the art at the time it was made, in view of the prior art when
considered as a whole.
[0126] Moreover, in view of the revolutionary nature of this
invention, it is clearly a pioneering invention. As such, the
claims that follow are entitled to very broad interpretation as to
protect the heart of this invention, as a matter of law.
[0127] It will thus be seen that the objects set forth above, and
those made apparent from the foregoing description, are efficiently
attained. Also, since certain changes may be made in the above
construction without departing from the scope of the invention, it
is intended that all matters contained in the foregoing description
or shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
[0128] It is also to be understood that the following claims are
intended to cover all of the generic and specific features of the
invention herein described, and all statements of the scope of the
invention which, as a matter of language, might be said to fall
therebetween. Now that the invention has been described;
REFERENCE NUMERALS
[0129] 1: cushion material [0130] 2: overlying sheet [0131] 3:
underlying sheet [0132] 4: base [0133] 5: vinyl leather [0134] 10:
motorcycle [0135] 11: female die [0136] 12: cavity [0137] 13: hot
water feeding device [0138] 14: male die [0139] 15: pantograph jack
[0140] 16: heat cutter [0141] 20: extruder [0142] 21: hopper [0143]
22: molding die [0144] 23: winder [0145] 24: take-off rolls [0146]
25: bath [0147] 26: take-up rolls [0148] 27: cutting device [0149]
30: resin molded article with a spring structure [0150] 31:
filament [0151] 32: burr
* * * * *