Moldless process for manufacturing foamed articles

Moldless process for manufacturing foamed articles is disclosed wherein a trim cover is first prepared as having a composite structure of an outer facing material such as fabric and an inner backing material of low melting point such as a thin foam of polystyrene and having a shape substantially corresponding to a final contour of the finished article; the trim cover is heated and forced to form a pre-shaped cover conforming to the final contour of the finished article preferably by means of a restraining frame such as basket or plastic cage configured to the final contour of the finished article; highly reactive polyurethane composition foamable at low internal pressure is poured inside the pre-shaped cover and allowed to foam and expand to fill substantially an entire volume within the pre-shaped cover; and then the pre-shaped cover is externally heated to around the melting temperature of the backing material so as to significantly shrink and virtually dissipate the backing material interposed between the facing material and the foaming polyurethane at the same time allowing the polyurethane to further expand to adhere to and become integral with the inner surface of the facing material, thereby an integral foamed article is produced without the use of any molds.

DESCRIPTION 
1. Technical Field 
This invention relates to a moldless process for manufacturing foamed 
articles composed of a foamed polyurethane body and a cover material 
enveloping integrally the body, without the use of any conventional mold. 
2. Background Art 
Many foamed articles such as vehicle seat cushions, head rests, arm rests 
and the like are generally manufactured through the use of molds, each 
cavity of which is configured in conformity to an outer contour of a final 
product to be desired. A cover or facing material such as fabric and 
natural or synthetic leather is set in the mold cavity by being laid along 
the entire inner surface of the mold cavity and shaped so as to follow the 
cavity inner surface. A liquefied foamable composition is poured to the 
inside of the cover material which has already set in the mold cavity, and 
allowed to foam and expand until it reaches to and becomes integral with 
the inner surface of the cover. Foaming composition exerts strong 
pressures through the cover material against the cavity wall, and thereby 
adheres firmly to and integrally with the inner surface of the cover. 
It has been long believed that the molds used for manufacturing foamed 
articles must have strong and heavy metallic structures in order to endure 
the strong pressure caused by foaming of compositions and to assure an 
accurate outer configuration of the final product. Such molds however, are 
very expensive to manufacture and difficult to manipulate. And further 
such molds require large installing space. Additionally, even if different 
surface configurations are required for the final products, the cavity 
wall shape of the conventional molds cannot be easily altered to meet such 
requirements. 
Although the foaming compositions produce strong pressure against the cover 
during foaming inside the cover, they can not perform to smooth and remove 
wrinkles and creases which have been formed in the cover fabric at the 
time of setting up in the mold. Accordingly, once wrinkles are formed in 
the cover at the time of setting, they can not have a chance to be 
smoothed or removed. Thus, the setting of the fabric was a very important 
procedure and the fabric had to be set in such an accurate and regulated 
manner that it might make intimate contact with the cavity inner surface 
without wrinkles. This required cumbersome and time-consuming manual 
labor. 
Moreover, the cover placed in the conventional mold may easily move out of 
the proper setting position prior to pouring the foaming material. Even if 
the fabric can be once set accurately in the mold, this setting state is 
only provisional but not fixed. Accordingly, the cover fabric may easily 
get out of its proper position by vibrations or shocks applied to the 
mold. However, checking of the fabric setting state is very hard during 
the manufacturing process. Particularly, after the lid of the mold is 
closed, it is impossible to check how the fabric is set in the mold. 
Accordingly, subsequent pouring and foaming steps of the foamable 
composition must be proceeded without checking of fabric setting state, 
running the great risk of producing defective articles. 
Another problem is that the foamable composition of the prior art required 
considerably long time period from pouring to completing the final curing 
of the composition, and therefore very long and vast production line was 
needed for accomplishing the manufacture of foamed articles and yet only 
low productivity was attained. 
The prior mold manufacturing has further problems as follows. Vacuuming 
technique is usually employed with perforations through the cavity wall in 
order to attract and bring the fabric into intimate contact with the 
cavity surface. Thus, the fabric itself must be of impermeable nature to 
assure attracting effect on the fabric. In this case the resultant 
products including arm rests, seat cushions and the like become 
uncomfortable because they are sticky to the touch with sweat or moisture 
attached and remaining on the outer impermeable surface thereof. 
DISCLOSURE OF THE INVENTION 
Accordingly, it is an object of the invention to provide a novel process 
for manufacturing a foamed article without use of any conventional mold of 
heavy and massive type, that is, a moldless process for manufacturing 
foamed articles. 
Another object of the invention is to provide a process for manufacturing a 
foamed article using a pre-shaped cover material conforming to a final 
outer configuration of a product such as head rest, arm rest, seat cushion 
and the like, in which the shape of each cover material can be easily 
checked even immediately before pouring the foamable composition, and if a 
mal-shaped cover is found it can be readily restored by additional 
reshaping process so as to avoid any risk of producing defective articles. 
Yet another object of the invention is to provide a moldless process which 
uses novel reactive polyurethane compositions having very fast reaction 
rate and capable of completing foaming and curing in a very short time 
period as compared with the prior art compositions. Novel fast 
polyurethane composition itself and a device for pouring the same into a 
pre-shaped cover material are also disclosed. 
A further object of the invention is to provide a process for manufacturing 
a foamed article in which permeable materials can be utilized as the cover 
of the foamed body without any inconveniences experienced in the 
conventional vacuuming technique. 
A feature of the invention resides in that a trim cover is first prepared 
and pre-shaped into a desired shape conforming to a final outer 
configuration of an article including, head rest, seat cushion and the 
like. The trim cover is composed of a surface or facing material, e.g. 
woven or knitted fabric, and a backing layer, e.g. a thin layer of foamed 
materials, adhered to the inside of the facing material. This trim cover 
may be prepared by attaching the low melting foamed backing material onto 
the inner surface of the planar facing material by adhesion etc. and then, 
cutting out and sewing up the facing material in accordance with the 
configuration of the final article. Alternatively the trim cover may be 
prepared by first cutting out and sewing up only the facing material and 
then lining the inner surface of the sewn facing material with the foamed 
backing material. Next, the cover may be shaped to the contour of the 
final article by heating and softening the low melting backing material, 
and then the backing material is cooled and hardened to obtain a 
self-supporting pre-shaped cover. The pre-shaped cover itself formed into 
the contour of the final article prior to pouring the foamable 
polyurethane and the forming method thereof constitute a part of the 
present invention. 
Polystyrene foam may be employed as a backing material of low melting foam, 
and alternatively a mixed foam of polystyrene and polyethylene also may be 
employed. Heating process for softening the backing material may be 
carried out by using a heater or blowing hot air. This hot air blow can be 
utilized also as pressurizing means for shaping the cover to the final 
article contour. After shaping, the hot air is changed to cool air to cool 
the backing material. 
Because the backing material shaped and hardened in accordance with the 
present invention may support the cover in the shape of the final article 
contour, such pre-shaped cover acts also like a mold when a reactive 
polyurethane composition is poured into the cover. Thus, the poured 
polyurethane can foam and expand into the shape of the final article. 
At the time when the polyurethane foam expands to fill substantially an 
entire space within the pre-shaped cover, the backing material of low 
melting foam is virtually dissipated. This is accomplished by externally 
heating the cover up to the melting point of the backing material or more. 
Heating causes the polystyrene foam to fuse and significantly shrink, and 
reduce its volume to such an extent that the foam is deemed to virtually 
disappear. At that time the foaming polyurethane reaches to the inner 
surface of the facing cover and adheres thereto. 
According to another feature of the present invention, where the outer 
surface of the final article has a concave portion, an outer shape 
restraining frame or cage is required for suppressing the outer surface of 
the cover. This outer shape restraining frame may be used with convex and 
planar surfaces as well as concave surfaces. In any event, this shaping 
frame is completely different from the conventional mold of heavy and 
massive type. This restraining frame may be a basket of wire netting or a 
cage of transparent plastic, and therefore is light and inexpensive and 
very easy to handle and install. Such shaping frame is preliminarily 
configured to a desired final contour of the article and capable of being 
easily pre-formed if minor changes are required in the final contour. Heat 
and pressure are applied to the inside of the trim cover received in the 
shaping frame in order to soften the backing material and press the cover 
against the frame to obtain a desired pre-shaped cover. The backing layer 
reaches its melting point and gets virtually dissipated around the time 
the inner space is entirely filled with polyurethane. The basket or 
transparent cage as shaping frame allows checking whether or not the 
pre-shaped cover is in good condition for receiving pouring of reactive 
polyurethane composition. 
It is important to select desirable reactive polyurethane compositions for 
carrying out the moldless manufacturing process of the present invention. 
Preferable foam materials are ones which have low foaming pressures and 
fast reaction rates. In accordance with the the present invention, such 
reactive polyurethane composition having a considerable high viscosity is 
delivered inside the pre-shaped cover. To accomplish this, a novel pouring 
nozzle may be used for discharging such viscous compositions. The pouring 
nozzle may be inserted through the cover to the inside thereof. The 
pouring nozzle has a predetermined length of residential passage within 
which the reactive polyurethane compositions flow slowly enough to change 
from liquid state into creamy state and get a desired viscosity. This 
pouring nozzle also constitutes a part of the present invention. 
The following formulations define reactive polyurethane compositions 
suitable for the moldless manufacturing process of the present invention. 
______________________________________ 
Ingredients Parts by weight 
______________________________________ 
Polyol (molecular weight 6000) 
60-80 
polyol (molecular weight 4000) 
40-20 
water 1.6-7.00 
amines 0.5-1.50 
chain extender 0.2-1.00 
surfactant 0.1-3.00 
cell opener 2.0-6.00 
TDI/MDI* 60-80/40-20 (%) 
35.0-60.0 
______________________________________ 
*TDI/MDI: toluenediisocyanate and methyldiphenydiisocyanate

PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION 
Referring now to the drawings, the present invention will be described in 
detail in connection with preferred embodiments. 
FIG. 1 shows in a partial sectional view a composite cover material which 
may be employed for carrying out the present invention. The composite 
cover material comprises a facing material 1 and a backing material 2. The 
facing material 1 is preferably of permeable material such as woven or 
knitted fabrics, while impermeable material such as natural and synthetic 
leathers, polyvinyl chloride or nylon sheets may also be employed. The 
backing material 2 is attached to the lower surface of the facing material 
1. The backing material 2 is a thin foamed product of low melting point 
compounds such as polystyrene. The facing material 1 and the backing 
material 2 may be bonded together through the use of suitable adhesive 3. 
Alternatively the polystyrene backing 2 may be directly stuck onto the 
back surface of the material 1 by foaming in situ. Preferred polystyrene 
to be used in the invention is commercially available under the name of 
"Styropor" or "Styrofoam." 
In one embodiment, the backing material 2 is first applied onto the facing 
material 1 in a flattened or leveled state to obtain a composite cover. 
Next, the composite cover is cut into a desired shape and size and then 
sewn to form a cover shell which is used for any finished article. As an 
example of a finished article, a head rest for the seat or chair is taken 
in the following description. FIG. 2 shows a cover 5 used for a head rest. 
It should be noticed that the present invention is applicable to any other 
finished foam articles such as an arm rest, a seat cushion, a stuffed toy 
or doll, and the like. The cover 5 is prepared by cutting the composite 
cover material shown in FIG. 1 into one or more pieces of desired sizes 
and sewing them together to form a box-like shape or rectangular 
parallelepiped configuration. Thus obtained cover is called a "trim 
cover". 
In another embodiment, the cover may be prepared by cutting and sewing only 
the facing material 1 into the final contour of any desired article, and 
then attaching suitable pieces of thin polystyrene foam to the inside 
surface of such facing material. 
In any event, because of stiffness of the foamed polystyrene backing 
applied to the inside of the cover 5, the cover 5 has shape retentivity or 
is self-supporting to some extent. In this stage, however, the cover 5 
does not have yet configurations exactly corresponding to the final 
product. Specifically, a surface 6 is flat and different from a concave 
portion 21 and a rear surface 7 is not a convex portion 22 of the final 
product shown in FIG. 5. A top surface 8 may be held in almost flattened 
condition by the foamed polystyrene backing 2 unless the latter is very 
thin. The cover 5 also has a bottom opening 9. 
The trim cover 5 is then subjected to a shaping process which comprises the 
steps of heating the cover and blowing air inside the cover whereby the 
configuration of the cover exactly corresponding to the final product is 
obtained. 
An example of the heating step is illustrated in FIG. 3 in which the 
surface material 1 is shown in broken lines and the backing 2 is shown in 
a solid line. Preferably, the cover 5 is inverted and supported in a frame 
or false frame 11 and pinched at its edges of the bottom opening 9 with 
clip means 12. Heating means 10 such as an electric heater is placed over 
the frame 11 and applies heat sufficient to bring the backing material 2 
to a plasticized state, e.g. 90.degree. C. The false frame 11 is 
preferably provided with a concave portion 13 so that the top portion 8 of 
the cover 5 when heated may hang down to conform to a final configuration 
desired. 
The backing material 2 thus brought to plasticized state is easily 
deformable when external forces are applied. FIG. 4 illustrates an example 
of applying deforming forces to the plasticized cover 5, i.e. blowing of 
air. At this time, the plasticized cover 5 is received and supported 
within a shaping frame 15 in order to be restrained by the frame 15. The 
inner shape of the shaping frame 15 is corresponding to or complementary 
to a desired outer contour of the final product for giving a desired 
configuration to the cover 5. Specifically, this restraining frame 15 has 
a concave portion 16 and a convex portion 17 respectively to form a 
concave surface 21 and a convex surface 22 of a pre-shaped cover 20 shown 
in FIG. 5. While it cannot be seen in FIG. 4, a convex surface like the 
convex portion 13 in FIG. 3 is formed at the bottom of the shaping frame 
15. 
An air blowing pipe 14 is inserted inside the cover 5 supported within the 
frame 15. Air pressure is supplied through the pipe 14 to the inside of 
the plasticized cover 5 such as shown by arrows in FIG. 4 so that the 
backing material 2 and the facing material 1 are forced to inflate and 
internally press against the shaping frame 15 having the configuration of 
the final product. Thus the plasticized cover 5 obtains its outer shape 
perfectly equal to the final product contour to be required. The air 
blowing is continued until the plasticized material is cooled down and 
solidified in the shape conforming to the shaping frame 15. When removed 
from the frame 15, a pre-shaped cover 20 as shown in FIG. 5 is obtained. 
The cover 20 is of an outer contour having a concave front surface 21, a 
convex rear surface 22 and a convex top surface 23 for a desired head 
rest. Thus solidified pre-shaped cover 20 can maintain its desired shape, 
in other words, it has shape retentivity by itself or self-supporting 
nature. 
Alternatively, a single frame member may be used for functioning as both 
false frame 11 and shaping frame 15. In this case, a single blowing pipe 
14 may be used for first applying hot air to the inside of the trim cover 
5 to soften and shape the polystyrene backing material 2 and then for 
applying cold air to cool and solidify the cover backing material 5. In 
other words, hot air blowing constitutes a process for heating and 
shaping, and cold air blowing performs a solidifying process. 
In any event, the shaping and restraining frame 15 (or 11) used in the 
present invention can be a light weight and inexpensive member such as a 
basket made of wire mesh or wire netting, or a transparent cage, because 
low or very low pressure is enough to cause the reactive polyurethane 
compositions used in this invention to foam and expand as described 
hereinafter. This means that the necessity for heavy and expensive molds 
conventionally employed in the art can be eliminated from the process for 
manufacturing the foamed articles. And the labor and investment can also 
be remarkably reduced. 
The basket-like frame or transparent cage as mentioned above can be used 
continuously in the subsequent steps including pouring and foaming of the 
polyurethane composition, and heating and shrinking of the backing 
material. 
Prior to pouring polyurethane, the pre-shaped cover 20 is closed at its 
bottom. Where the final article is a head rest, the pre-shaped cover 30 
may be provided therein with inserts such as reinforcing members, core 
members, fittings or the like. An example of such inserts is shown at 25 
in FIG. 5. This insert 25 comprises a base 26, and a core member 27 
supported by legs 28 extending outwardly through the base 26. The core 
member 27 and each upper half of the legs 28 are to be contained within 
the shaped cover 20, and the base 26 closes the bottom opening of the 
cover 20 and seals it. If an employed insert is not supported by legs 28 
and the like but must be floating in the cover 20, a false positioning 
member (not shown) of the same material as the backing layer 2, i.e. 
polystyrene may be used to suspend such insert from the inner surface of 
the cover top. Where pivot points 28a of the legs 28 or other moving parts 
are to be included in the cover 20, protecting sleeves or wrapping films 
(not shown) of polystyrene or other material may be used to surround such 
moving parts and prevent them from being clogged with foamed polyurethane. 
Such protecting sleeves and films will shrink considerably and virtually 
disappear upon heating taken afterward to heat-shrink polystyrene backing 
2, and will not injure any function of such moving parts. 
Into the pre-shaped cover 20 thus closed, reactive polyurethane 
compositions in the liquid state are poured directly through the use of an 
appropriate injector or nozzle. Since the foamed polystyrene of the 
backing material 2 is relatively hard and of unicellar cells, it can well 
prevent poured liquid polyurethane from leaking out of the facing material 
1. 
Preferably, a pouring nozzle 30 as shown in FIG. 6 is employed in the 
present invention in order to supply the reactive polyurethane 
compositions in a desired creamy and viscous state into the cover 20. The 
pouring nozzle 30 is of a thin tube and can pierce the facing material 1 
and the backing material 2, e.g. at the rear surface 22 thereof of the 
cover 20. 
FIG. 7 represents in greater detail a cross sectional view of the pouring 
nozzle 30. The nozzle 30 is composed of a thin tube having at its one end 
a flared inlet and a closed bottom at the other end. The flared inlet is 
connected with a supply conduit 29. Liquid reactive polyurethane 33 comes 
from supply source (not shown) through the conduit 29 into the nozzle 30. 
The nozzle 30 may be of plastic such as polyethylene or polystyrene. The 
nozzle 30 has one or more outlets 32 opening near the bottom. There is a 
traveling passage 31 extending between the inlet and the outlet 32. The 
travelling passage 31 determines a "residential time" in which the 
reactive polyurethane changes its state from liquid (low viscosity) to 
desirable high viscosity while flowing from the inlet to the outlets as 
indicated by arrows. In this sense, the travelling passage 31 may be 
called "residential passage". The reactive polyurethane is converted to 
creamy and highly viscous state within the residential passage 31 and is 
extruded through the outlet 32 to the inside of the cover as shown at 34 
and overspread within the cover. 
Specifically, the "residential time" during which the reactive compositions 
should be staying in the residential passage 31 is at least about 1 second 
and needs not to exceed 4 seconds in case that the preferred polyurethane 
composition mentioned hereinafter is employed. If the prior art 
polyurethane compositions such as so called "hot curing" polyurethane are 
used, it takes about 20 seconds to convert such compositions from liquid 
state to creamy state. In contrast, a creaming time for the preferred 
composition of the present invention is very short, and therefore the 
travelling passage (residential passage) 31 of the nozzle 30 can be 
shortened whereby the efficiency and operability of the total 
manufacturing process are greatly improved. 
Although the length of the residential passage 31 is dependent upon the 
pressures exerted by the supply source of the liquid polyurethane, it is 
believed that the length of about 5 cm is sufficient for the 
under-mentioned polyurethane composition. The nozzle 30 may have a 
diameter of about 1 cm. 
The nozzle 30 is inserted preferably horizontally into the cover 20 so as 
to avoid influences of gravity upon the flow of the compositions 33 and 
34. Further, it is desired that the nozzle 30 be positioned so as to 
insure that the creamy composition 34 would not contact a localized 
portion of the inner surface of the cover 20, but evenly spread all over 
the entire space within the cover 20. 
Upon completion of pouring a predetermined amount of the reactive 
polyurethane composition, the nozzle 30 is removed from the cover 20. The 
resiliency of the surface material 1 and the backing material 2 will 
restore a hole pierced therein by the nozzle 30, but if necessary a 
closing member such as a tape may be applied to such hole portion. 
An example of the preferred polyurethane composition to be poured within 
the pre-shaped cover of the invention is as follows: 
______________________________________ 
Components Parts by weight 
______________________________________ 
Polyol (molecular weight 6000) 
70.00 
polyol (molecular weight 4000) 
30.00 
water 2.80 
amines 1.00 
chain extender 0.50 
surfactant 1.50 
cell opener 4.00 
TDI/MDI* 80/20 (%) 45.00 
______________________________________ 
*TDI:toluenediisocyanate MDI:methyldiphenyldiisocyanate 
This composition is highly reactive and able to attain a high degree of 
polymerization in a few seconds. Thus, the composition poured through the 
nozzle 30 will foam and expand to fill the interior of the cover 20 as 
shown at 35 in FIG. 6 shortly after removing of the nozzle 30. This 
composition can expand at a very low internal pressure so that the cover 
20 with the backing 2 of impermeable foamed polystyrene layer will not be 
ruptured by an expanding pressure of the polyurethane foam. However, for 
greater safety purpose, the backing 2 may have perforated pin holes (not 
shown) for releasing internal gases resulting from the expansion of the 
polyurethane. 
When the polyurethane foam 35 has expanded to fill substantially the entire 
space within the cover 20, the nearly finished product is subjected to a 
heating process for diminishing and virtually extinguishing the backing 
layer 2. Heating is externally applied to bring the backing material 2 to 
its softening or melting point of about 110.degree.-130.degree. C. FIG. 8 
illustrates a heating furnace 37 containing the nearly finished product. 
Alternatively, heating wires may be wrapped around the frame 15 shown in 
FIG. 4 and an electrical current may be passed through the wires in this 
heating process. 
By externally heating, the backing material 2 of polystyrene is melted and 
extremely shrunk to one tenth or even one hundredth of its original size 
so that it may be considered to virtually disappear. At this point, the 
polyurethane foam 35 reaches the inside surface 1a of the fabric 1 of the 
pre-shaped cover 20 as shown in FIG. 9 and still continues to expand and 
press the cover outwardly until it finally cures. The expanding 
polyurethane 35 is stil in sufficient tacky condition to strongly adhere 
to the inside 1a, but it loses almost of all its fluidity so that it will 
not soak out of the fabric 1. 
As an alternative, the backing material 2 of foamed polystyrene may be 
provided with a plurality of small holes 4 as shown in FIG. 1A. In such 
case, portions of the expanding polyurethane foam 35 still in tacky state 
are permitted to pass through these holes 4 to reach the inside la of the 
cover before disappearance of the backing material 2. This insures making 
a positive and mechanical linkage between the fabric 1 and the foam 35. It 
is apparent that these holes 4 may also be useful for releasing gas from 
the interior of the cover. 
Since the composition employed in the present invention has an extremely 
high reaction rate, it reaches a highly polymerized condition very 
rapidly, for example, within 5 seconds in case of a 5 liter cover, or in 
12 seconds in case of 20 liter cover. Accordingly, the foamed body 35 
conforms to the pre-shaped cover very soon, and it can be removed from the 
restraining frame 15 in a very short period without fear that its outer 
configuration might be destroyed. At the time the polymerization reaction 
of the configured foamed mass 35 exceeds 90% of the maximum degree within 
15 minutes, the nearly finished product can be handled manually or in an 
automatic machinery to be conveyed to subsequent stages, e.g. packaging 
station whereby operational time can be considerably reduced. 
FIG. 10 illustrates a modified form of the invention in which a mixed foam 
of polystyrene and polyethylene is employed as a backing layer applied 
onto the facing material 1. The backing layer of mixed foam is softer and 
more pliable than the backing material of only polystyrene and easier to 
handle in the sewing operation of cover 1. Moreover, the mixed foam 
backing enjoys an additional advantage in that stronger linkages are 
produced between the cover fabric and foamed polyurethane after such 
backing layer was heated. That is to say, when heated, cell structures in 
the mixed backing layer 2' are divided into polyethylene beads and 
polystyrene beads, and the latter are readily shrunk and dissipated to 
leave holes in the remaining polyethylene layer through which portions 35A 
of the foaming polyurethane 35 pass to reach and adhere to the inside 1a 
of the fabric 1. The polyethylene layer 2' remains in a liquefied state 
between the fabric 1 and the polyurethane foam body 35. Again, it is 
preferable that the mixed foam backing is provided with pin holes for air 
releasing 
INDUSTRIAL APPLICABILITY 
According to the invention, the pre-shaped cover can hold its final shape 
by itself and be supported by simple, light and see-through frame or cage 
over several processing stages whereby the use of heavy and massive molds 
of conventional type is eliminated. Further, visual inspection can be 
easily done through the supporting frame or cage in order to ascertain 
whether the pre-shaped cover received in the frame holds its desired final 
shape even immediately before pouring the polyurethane liquid. Therefore, 
in the present invention, it is most unlikely to proceed to pour the 
polyurethane into mal-shaped cover, whereas the conventional mold does not 
permit any visual inspection after setting the fabric in the mold and 
closing the lid of the mold so that the risk of defective products is 
always involved. In the present invention, if a mal-shaped cover is found 
before commencing pouring of polyurethane, it can be easily removed from 
the supporting frame or cage and returned to the shaping station where the 
mal-shaped cover is again subjected to heating for re-shaping purpose and 
corrected to its proper configuration. Thus, savings of material can be 
attained in the invention.