Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a method and an apparatus for
molding polyurethane soles fo~ footwear.
More specifically, the invention relates to the molding
of soles for footwear using polyurethane of two different colors
and~or physical and chemical properties. In the production of soles
for sports shoes or the like, it is common practice to use a
single material such as polyurethane or polyvinyl chloride; and
to make the soles in two separate and distinct molding operations
using different compositions for the two sole portions. The
resulting soles have two differently colored portions and/o~ two
portions with different properties such as hardness.
One conventional two color molding technique is disclosed,
for example, in applicant's Canadian Patent No. 977,917 , issued
November 18, 1975 . In the conventional method, a first mold
cavity is formed at a first molding station where a first injec-
tion of moldable material is effected, and the mold is moved to
a second molding station where a second mold cavity is formed
and a second moldable material is injected into the second mold
cavity. The first mold cavity is formed by a mold top in the
form of a dummy last, mold sides or side rings and a mold piston.
The second mold cavity is defined by the mold piston and first
sole portion thereon, a lasted upper and different portions of
; the mold sides or another set of mold sides. In such a method,
it is necessary to inject the moldable material at two separate ~~
locations to permit the first sole portion to at least partially
cure to a hardness sufficient to prevent deformation thereof
during the second injection. With the large injection units used to
inject polyvinyl chloride, only one injection unit can be present at
any one molding station.
It will be appreciated that the conventional method
requires a large turntable with a plurality of molds - usually
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20 - 24 - in order to operate efficiently and economically. With
a material such as polyurethane which requires an approximately
3 minute curing time, a large apparatus has been a necessity.
Moreover, for two color injection a four component dispensing
system is required, i.e. resin and hardener containers must be
provided at each of the two molding stations. When injecting at
two separate, spaced apart locations, the edge of the mold con-
taining the injection port for the second material becomes
clogged during the first injection step, thus making injection of -
the second ~aterial difficult if not impossible.
Thus, it is readily apparent that there exists a need
for a simple method and apparatus for injecting two component
polyurethane or the like. By two component is meant polyurethane
of two different colors, or polyurethane compositions having
different physical and/or chemical properties for each molding
operation. Alternatively, two similar compositions can be used.
The object of the present invention is to provide a
method and an apparatus for injecting two component polyurethane
soles for footwear which are relatively simple and which facili-
tate the production of such soles. - -
According to one aspect of the invention, there is pro-
vided a method for molding two component soles for footwear of
polyurethane or the like comprising the steps of molding a first
sole portlon at a first molding station; moving the first sole
portion along a path of travel such that it returns to said first
molding station after a predetermined period permitting at least
partial curing of the flrst sole portion; and thereafter simul- - -
taneously molding a second sole portion on said first sole portion
and a new, separate first sole portion at said first molding statio~
~ According to another aspect of the invention, there is
~ provided an apparatus for molding two component soles for
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footwear of polyurethane or the like comprising a turntable; a
plurality of spaced apart mold bottoms carried by said turntable;
mold top means carried by said turntable for forming a first
mold cavity with each of said mold bottoms one at a time; mold
sides; a plurality of lasts carried by said turntable for
receiving uppers and forming second mold cavities with said mold
bottoms and mold sides; said lasts being equal in number to said
mold bottoms; and means for simultaneously injection one compon-
ent into a first mold cavity and the second component into a
- 10 second mold cavity, whereby simultaneously to complete a two
component sole and mold a newr separate first sole portion.
; By simultaneously injecting one component of a two
component sole into one mold and a second component of a two
component sole into another mold at the same molding station,
the number of molding stations can be substantially reduced.
Moreover, after the initial injection of a first component into
a plurality of molds on a turntable to form a plurality of
first sole portions, simultaneGus injection of the second
component to complete the soles and injection of new first
components can take place on a continuous basis. It is also
possible to use a single source of polyurethane resin and a
single injection unit. With such an arrangement, three material
feed systems are required instead of four One feed system
supplies the polyurethane resin to a pair of mixing devices, the
second system supplies the hardener and other materials, e.g.
coloring agents to the first component mixing device and injec-
tion nozzle, and the third system supplies the hardener and other
materials to the second component mixing device and injection
nozzle. Thus, not only do the method and apparatus of the
present invention facilitate production, but they can lead to
a substantial saving in machinery costs. The use of a single
; injectiOn unit having two nozzlesmeans that the safety features
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normally required are also red-~ced in number, i.e. safety features
may be required for one injection unit instead of two.
With the method and apparatus of the present invention,
the molds pass an operator immediately before molding operations,
and the face of the molds containing the injection ports can be
cleaned In known two component molding methods,molding of one
component occurs at a first molding station and molding of a
second component occurs at a second molding station remote from
the first station. Thus, if the second injection port becomes
blocked during the first molding step, it may be difficult or
impossible to effect the second molding step unless an operator
; is present to clean the face of the mold containing the injection
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ports. In other words, instead of two cleaning operations for
molding at two separate locations, only one cleaning operation is
required with the method and apparatus of the present invention.
The invention will now ~e described in greater detail
with reference to the accompanying drawings, which illustrate
preferred embodiments of the invention, and wherein:
Figure 1 is a schematic plan view of a molding apparatus ~ ~
in accordance with the present invention; ~ - -
Figure 2 is a schematic elevation view of the apparatus
of Fig. l;
Figures 3 to 5 are schematic cross-sectional views of
molds and sole components during molding in accordance with one
embodiment of the method of the present invention;
Figure 6 is a longitudinal sectional view of the molds
$ and sole components of Fig. 5;
Figures 7 to 9 are schematic cross-sectional views of
molds and sole components during molding in accordance with a
second embodiment of the method of the present invention;
Figures 10 to 13 are schematic cross-sectional views of
molds and sole components during molding in accordance with a
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third embodiment of the method of the present invention; and
Figures 14 to 16 are schematic cross-sectional views
of molds and sole components during molding in accordance with
a fourth embodiment of the method of the present invention.
With reference to the drawings and in particular to
Figs. 1 and 2, the molaing apparatus of the present invention
includes a base 1 resting on the floor and a turntable 2 rota-
tably mounted on the base 1 for rotation about the vertical
longitudinal axis of the machine. The turntable 2 is generally
circular and is provided with a plurality of molds (not shown
in Figs. 1 and 2) spaced equidistant apart about the periphery
of the turntable for receiving a liquid polyurethane mixture
from a pair of injection units 4 and 5. Polyurethane resin, --
hardener and any desired additives are fed into the units 4 and 5
and then injected into the molds via nozzles 6 and 7, respectively.
The two injection units 4 and 5 can be replaced by a single unit
(not shown) With a pair of nozzles and separate mixing facilities.
The separate mixing ~acilities would both b~ connected to a
single source of polyurethane resin, and to separate sources of
hardener and additives. The two injection units 4 and 5 or the
pair of nozzles on the single unit are located at one molding
station for simultaneously injecting polyurethane into two
~ separate molds.
-' A central column 8 on the turntable 2 is provided with
last holders 9 (one shown) located above the turntable, the
number of last holders 9 being equal to the number of molds.
Each last holder 9 supports a dummy or false last 10 on one
surface and a last 11 on an opposite surface thereof, or alter-
natively a pair of lasts on such surfaces. The last holders 9
are rotatably and vertically slidable on the column 8 so that a
first mold cavity can be formed using a false last 10 to produce
a first sole portion. Conventionally, after formation of the
first sole portion, the false last 10 is then raised to open the
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first mold which is moved with the turntable 8 to a second
molding station. Before reachin~ the second molding station,
the last holder 9 is rotatea so that a lasted upper, i.e. an
upper on the last 11 extends downwardly. The lasted upper is
moved downwardly to close the mold at a second molding station,
a second sole portion is molded using a second injection unit,
and the lasted upper with the complete sole is moved upwardly
to open the mold. Finally, the completed article of footwear
is moved with the turntable to an unloading station which corres-
ponds to the loading station for uppers. Thereafter, the method
is repeated continuously.
- Referring now specifically to Figs. 3 to 5, in accord-
ance with the method of the present invention, first and second
sole portions of a two component sole are molded separately and
simultaneously at a single molding station using a pair of
injection units or a single injection unit with two separate
injection nozzles. The first step in the method is to form a
first mold cavity 12 using a false last, which is in the form of
a vertically movable mold bottom 13, and a double faced sole
plug 14. The sole plug 14 is rotatably mounted on a turntable 2.
The two faces of the sole plug 14 contain recesses 15 and 16 for
defining the first mold cavity 12 and a second mold cavity 17.
Initially, the second mold cavity 17 is formed by a last 18 with
an upper thereon (hereinafter referred to as a lasted upper),
side molds 19 and the face of the sole plug 14 containing the
recess 16. A first component in the form of a mixture of poly-
urethane resin, hardener and other additives is injected into
the first mold cavity 12 to form a first sole portion 20. In
the same manner, a first sole portion is formed in each of a
plurality of molds of the above-described type on a turntable
(not shown). The first sole portions 20 ultimately form the
; outer or bottom portion of the sole.
Upon completion of all of the first sole po~tions 20,
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the first mold, h~ving completed a circular path of travel,
returns to the molding station. However, before reaching such
molding station, both mold cavities 12 and 17 are opened by
moving the false last 13 downwardly, moving the side molds 19
apart and moving the lasted upper 18 upwardly, leaving the first
sole portion 20 in the recess 15 in the sole plug 14. The sole
plug 14 is rotated to a position in which the lasted upper 18
is opposed by the first sole portion 20, and the empty recess 16
in the opposite face of the sole plug 14 opposes the mold bottom
or false last (Fig. 4). Finally, the mold is closed to form new
mold cavities, and a second sole portion 21 (Figs. 5 and 6) is
molded using a second color polyurethane or a polyurethane compo-
sition having different properties from that used in the first
sole portion 20. At the same time as the second sole portion 21
~ is being molded, i.e., simultaneously with the in~ection of the
; second component into the mold cavity 17 via an injection port
23, a second batch or shot of first component is injected into
the mold cavity defined by the recess 16 and the mold bottom 13
via an injection port 24. It is readily apparent that the second
sole portion 21 forms an inner sole on the outer sole (first sole
portion 20). It is also apparent that after all of the first
sole portions are molded initially, the second mold cavities are
formed by a first sole portion on the sole plug 14, a lasted
upper 18 and the mold sides 19. Following completion of the
initial molding of the first sole portions, the method is con-
tinuous.
Referring now to Figs. 7 to 9, in accordance with a
second embodiment of the present invention, first and second molds
generally indicated at 25 and 26 are formed on a single plate 27,
which is rotatable about a vertical axis 28. In a first molding
operation, a first mold 25 including a vertically movable mold
top or false last 29 and a sole plug or mold bottom 30, is
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closed by moYin~ the false last 29 downwardly onto the mold
bottom 3a and a first sole portion 31 is molded by injecting a
first polyurethane composition into mold cavity 32. At the same
time, the second mold 26 is closed to form a mold cavity 33 on
the opposite side of the top surface of the plate 27. The
second mold 26 is formed by a mold bottom 34, mold sides 35 and
lasted upper 36.
Upon completion of the first sole portion 31, the molds
25 and 26 are opened by moving the false last 29 upwardly, by
moving the mold sides 35 apart and the lasted upper 36 upwardly,
and the plate 27 is rotated about the axis 28 to reverse the
positions of the mold bottoms 30 and 34 (Fig. 8). A new mold
cavity 37 similar to cavity 32 is formed using the false last 29
and the mold bottom 34; and a new mold cavity 38 similar to cavity
33 is formed using the first sole portion 31 on the mold bottom 30,
the mold sides 35 and the lasted upper 36. As illustrated in -
Fig. 9, a new first sole portion 39 is formed in the mold cavity
37, and simultaneously, a second sole portion 40 is molded in the
mold cavity 38. Thereafter, the method is continuousO While a
first sole portion is being molded in one mold 25, a second sole
portion is being molded in the second mold 26 at a single molding
station using a pair of injection units 4 and 5 (Figs. 1 and 2)
or a single injection unit with two injection nozzles.
In another embodiment of the method of the present
invention illustrated in Figs. 10 to 13, four mold bottoms 41, 42,
43 and 44 are utilized with a single mold top or false last 45
to form one mold generally indicated at 46, and with side molds
47 and a lasted upper 48 to form a second mold generally indicated
at 49. The sequence o~ operation is essentially the same as in
the other embodiments of the invention. The mold bottoms move
in a generally rectangular path of travel. Firstly, the molds
46 and 49 are closed, with the mold bottom 41 forming the base
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of the mold 46, and a first sole portion 50 is molded in recess
51 in the top of the mold bottom 41 (Fig. 101. The molds 46 and
49 are opened, and the mold bottoms are moved to the next
adjacent corner of the rectangular path of travel in the direc-
tions of arrows A, B, C and D (Fig. 11). A second set of molds
46 and 49 are formed, the mold bottom 41 forming the base of the
mold 49 and the mold bottom 42 forming the base of the mold 46.
Another first sole portion 52 is molded in recess 53 in the top
of the mold bottom 42, and simultaneously a second sole portion
54 is molded onto the bottom of the lasted upper 48. The mold
bottom moving steps and double molding operations are repeated
for each of the mold bottoms, first sole portions 55 and 56
being molded in recesses 57 and 58 in the mold bottoms 43 and 44,
respectively, and second sole portions 59 and 60 being molded in
the mold 49 on the first sole portions 52 and 55, respectively,
Thereafter, the method is continuous. In the next simultaneously
molding operations, a new first sole portion is molded in the
, recess 51 in the mold bottom 41 and a second sole portion is
molded onto the first sole portion 56 in the mold bottom 44.
By continuously moving the mold bottoms in the direction of
arrows A, B, C and D, the two component soles can readily be
mass produced.
In Figs. 14 to 16 the same reference numerals are used
to identify elements similar to those in Figs. 10 to 13.
The apparatus and method of Figs. 14 to 16 are similar
to those of Figs. 10 to 13, except that the mold bottoms 41, 42,
43 and 44 are moved through a circular, clockwise path of travel.
A series of molds 46 are formed using the mold bottoms 41, 42,
43 and 44, and a mold top or false last 45. By the time a first
sole portion 55 is being molded in the mold bottom 43, a second
sole portion 54 is being molded onto, between and bonded to the
lasted upper 48 and the first sole portion 50. Thereafter, the
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process is continuous, with the mold bottoms 41, 42, 43 and 44
virtually constantly in use, and the simultaneous injection of
the first and second components being effected during each molding
operation.
of course, in each of the method of Figs. 10 to 13 and ~-
- 14 to 16, the finished sole can and preferably is retained in
the mold 49 until it reaches a location immediately before the
location of the mold 46. This would provide sufficient time for
complete curing. MoreoVer, the molds 46 and 49 would be opened
simultaneously, new molds closed, and the mold injection ports
cleaned simultaneously.
In the first embodiment of the apparatus described
hereinbefore (Figs. 3 to 5), the top surface of the mold bottom
13 is coated with polytetrafluoroethylene, which facilitates
separation of the mold bottom from the first sole portion. By
~ the same token, the mold top or false last used to form the first
- mold in the apparatus of Figs. 7 to 16 can be coated with polytet-
rafluoroethylene.
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SUPPLEr~ENTARY DISCLOSURE
The principal disclosure describes several different
embodiments of the apparatus for molding polyurethane soles in
which molding of two sole portions occurs simultaneously at a
single mold station.
In accordance with another embodiment of the invention
the first sole portion is molded in a-mold cavity defined by a
recess in a sole plug or mold bottom, which is mounted on one
arm of a generally L-shaped carrier, and a mold cover or false
last; the mold bottom is rotated around an inclined axis to a
second molding location beneath a lasted upper; a second mold
cavity is formed using the mold bottom and first sole portion,
mold sides and the lasted upper; and a second sole portion is
molded in the second mold cavity. At the same time, another
first sole portion is molded in a new first mold cavity defined
by a second mold bottom on the other arm of the L-shaped carrier
and the mold cover or false last.
The apparatus for carrying out the above method includes
a generally L-shaped mold carrier,with a mold bottom mounted on
the outer end of each arm thereof. Thus, the mold bottoms are at
a right angle to each other; A sole cover opposing the vertically
disposed mold bottom completes one mold cavity for molding the
first sole portion. The second mold bottom is horizontally
disposed, and cooperates with mold sides and a lasted upper to
form the second mold cavity. After a first sole portion has been
molded in one mold cavity, operation of the apparatus is contin-
uous, with first and second sole portions being molded simultan-
eously at the same molding station.
In practice, the first mold is opened by moving the mold
cover outwardly away from the mold bottom. The second mold is
opened by moving the mold sides outwardly away from the lasted
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upper, moving the lasted upper upwardly away from the mold bottom,
and moving the mold bottom downwardly away from the lasted upper.
Thus, the mold carrier is moved downwardly with the bottom molds.
In the lower position, the mold carrier can be freely rotated
around an inclined axis (through the corner of the L), so that
the mold bottoms change places.
The additional embodiment of the invention will now be
described with reference to the accompanying drawings, wherein:
Figures 17 to 19 are schematic, partly sectioned views
of molds and sole components or portions during molding in accord-
ance with a fifth embodiment of the method of the present
invention.
With reference to Figs. 17 to 19, in accordance with the
fifth embodiment of the invention first and second molds generally
indicated at 61 and 62 are provided at each molding station on
- the turntable 2 (Figs. 1 and 2). The molds 61 and 62 are defined
in part by a pair of mold bottoms 63 and 64 mounted on the outer
free ends of a generally L-shaped carrier 65. The carrier 65 is
rotatably mounted on the turntable for rotation around an inclined
axis 66, which extends through the corner of the L (in this case
through the point where such corner would be).
Referring to Fig. 17, the mold bottom 63, which is vert-
ically disposed in the first molding position, forms a first
mold cavity 67 with a mold top or false last 68. A first sole
portion 69 is injected into the mold cavity 67 through a nozzle
70 and a molding port 71 in the mold top 68. At the same time,
a second mold cavity 72 is formed on the mold bottom 64 using
` mold sides 73 and 74, and a lasted upper 75.
Upon completion of the first molding operation, the
mold 61 is opened by moving the mold top 68 outwardly in the
direction of arrow 76 (Fig. 18), leaving the first sole portion
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69 on the mold bottom 63. The mold 62 is also opened by moving
the mold sides 73 and 74 outwardly in the directions of arrows 77,
moving the lasted upper 75 upwardly (arrow 78~ and moving the
mold bottom 64 downwardly (arrow 79). Of course, because the
mold bottom 64 is mounted on the carrier 65, it is necessary to
move the whole carrier and both mold bottoms 63 and 64 downwardly.
The carrier 65 is then rotated around the inclined axis 66 in the
direction of arrow 80, so that the mold bottom 64 assumes the
vertical orientation and the mold bottom 63 assumes the top,
horizontal position (Fig. l9).
In the second molding position, the molds are again
closed. A new first mold cavity is defined by the mold bottom 64
and the mold top 68, and a new first sole portion 81 is injected
into the mold cavity via the port 71. At the same time, a second
mold cavity is defined by the mold bottom 63 and the first sole
portion 69, mold sides 73 and 74, and the lasted upper 75. A
second sole portion 82 is injected into the second mold cavity
through an injection nozzle 83 ana a molding port 84 in the mold
side 74.
; ~ 20 It will be appreciated that the first sole portions form
the outer or bottom portions of the sole, and the second sole
portions form the inner or so-called midsole which connects the
outer sole portior to the 1asted ~pper.
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