Note: Descriptions are shown in the official language in which they were submitted.
2123046
The present invention relates to an appara-
tus and method for molding footwear from plastics mate-
rial and in particular for forming a seamless upper for
footwear.
There are many examples of injection molded
footwear. Typical of such footwear and the apparatus
for producing it is described in U.S. Patent 3,160,921
issued December 15, 1964 to Herbert Ludwig. As with
most such footwear, the Ludwig boot has a seam extend-
ing from the toe to the vamp and similarly at the heelalong the Achilles area. This seam is produced by the
mold halves which split in a vertical plane.
The problem appears to lie in the fact that
such injection molds, which are lasted molds, must be
split in order to accommodate the last and to be able
to properly demold the upper from the last.
In many cases injection molded boots are
produced on carrousel molding machines having a plu-
rality of stations. A split mold for forming the upper
is also located on each station on the carrousel. The
lasts are disposed horizontally and the mold halves
split along horizontal planes onto the lasts while the
sole plate moves horizontally towards the split mold to
close the mold. Thus the resulting upper has a seam in
a plane along the axis of the last.
It is an aim of the present invention to
provide plastics molded footwear having a seamless
upper.
It is a further aim of the present invention
to provide an apparatus for injection molding a foot-
wear upper without a visible seam.
It is a further aim of the present invention
to provide a carrousel apparatus for producing footwear
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including an upper and sole wherein the upper is seam-
less.
-It is a further aim of the present invention
to produce a calf-length boot having a seamless upper.
An apparatus in accordance with the present
invention comprises a first mold member having wall
surfaces defining a cavity conforming to the outer sur-
face of at least the lower portion of a footwear upper.
The first mold defining an opening for the cavity cor-
responding to the demarcation of the upper. A last ismounted for movement in the cavity between a first
position in the cavity, adjacent but spaced from the
wall surfaces of the cavity, to define the inner sur-
face of at least the lower portion of the upper and a
second position at a greater distance from the cavity
wall surfaces to allow demolding of the upper from the
last. Means are provided for closing the opening of the
first mold thereby closing the cavity with the last in
the first position and injection means are provided for
injecting plastics material into the cavity to fill the
space between the last and the mold wall surfaces in
order to form the seamless upper.
In a more specific embodiment, the means for
closing the opening of the first mold is a second mold
defining a second cavity shaped to form at least an
intermediate sole portion.
In a more specific embodiment, the apparatus
of the present invention includes a frame and the first
mold member is mounted to the frame. The last is also
mounted to the frame and is movable in an axis relative
to the first mold within the cavity of the first mold.
The second mold member is mounted in vertical alignment
with the axis of the last and the first mold such that
at least one of the first and second molds is movable
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in the axis relative-to the frame from a first position
with the last in the first position within the cavity
of the first mold and with the first mold spaced from
the last sufficient to allow an injected plastics
material to form an upper, to a second position wherein
the first and second molds are separated and the last
is moved outwardly of the cavity of the first mold to
permit demolding of the upper from the last.
In a more specific embodiment of the present
invention, injection means for injecting plastics is
provided in the first mold and means are provided for
actuating the injection means in the second position of
the cycle.
In a further embodiment, a second injection
means is associated with the second mold to inject a
plastics of a different density and/or a different
colour for forming the sole which may be different from
the density of the plastics material forming the upper.
A method in accordance with the present
invention comprises providing a molding station having
first and second mold parts movable towards each other
in a vertical axis and a last in a cavity of the mold
parts wherein the cavity of the first mold part defines
with the last, at least a lower portion of the upper
and the cavity of the second mold part defines at least
an intermediate portion of the sole of the footwear
with the last. The steps include moving at least one of
the first and second mold parts towards each other in
an axis from a position wherein the first and second
mold parts are spaced apart to a position wherein the
mold parts are closed onto each otheri simultaneously
moving the last to a position within the cavity of the
first mold part; injecting plastics material into the
cavities of the first and second molds; cooling the
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plastics material being molded; separating the molds
along the vertical axis; and, moving the last outwardly
of the first mold and demolding the upper from the
last.
Having thus generally described the nature
of the invention, reference will now be made to the
accompanying drawings, showing by way of illustration,
preferred embodiments thereof, and in which:
Figure 1 is an end elevation partly in
cross-section of a molding station in accordance with
the present invention;
Figure 2 is an end elevation partly in
cross-section similar to Figure 1 showing the parts in
a different operative position;
Figure 3 is a fragmentary end elevation
partly in cross-section similar to Figure 2, showing
further parts in the same operative position;
Figure 4 is an end elevation of the molding
station similar to Figure 3 with the parts in a dif-
ferent operating position;
Figure 5 is a fragmentary vertical cross-
section of a molding station showing another embodiment
of the present invention;
Figure 6 is a fragmentary vertical cross-
section similar to Figure 5 showing the parts in a
still different operative position;
Figure 7 is a fragmentary vertical cross-
section similar to Figures 5 and 6 showing the parts
thereof in a still different operative position;
Figure 8 is a fragmentary vertical cross-
section similar to Figure 7 showing the parts in a dif-
ferent operating position; and
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Figure 9 is a fragmentary side elevation
partly in cross-section of a detail of the present
invention showing its second molds.
Referring now to Figures 1 to 4 there is
shown a molding station 10 which could be part of a
carrousel. A typical carrousel might be a Union Car-
rousel Last Machine, which has been adapted to the par-
ticular molding operation of the present invention.
Such a carrousel last machine is well known and might
be a a low pressure direct injection onto an upper and
sold by MAIN Group, and will not be described in the
present specification. Only a single molding station
which would be repeated at several locations on the
carrousel, will be described.
As shown in Figures 1 to 4 the molding sta-
tion 10 includes a frame 12, including posts Z6, sup-
porting table 25, and a first mold member 16 on
frame 12 and adapted to slide vertically relative to
the table 25.
A first mold member 16 includes a one piece
mold block 36 having a cavity 22 defined by surfaces
which replicate the outer surface of the finished lower
portion, at least, of the upper. A bracket 34 slides on
posts 26 and is fixed to telescoping hydraulic cyl-
inder 28 which drives the bracket 34.
A sub-frame 38 is located below the table 25
and is adapted to slide on columns 26 which support the
table 25. The sub-frame 38 mounts rods 40 which in turn
support a last 18 The last 18 is movable within the
mold block 36 As shown in Figures 2 and 4, the last 18
includes a collar 48 which fits tightly at the neck 50
of the mold block 36. The rods 40 slide in seals pro-
vided at the collar 50. Compression springs 32 are pro-
~1~3D~I;
vided on posts 26 and extend between bracket 34 and
sub-assembly 38.
Hooks 44 may be fixed to the table 25 and
extend downwardly to provide the lower limit of travel
of the sub-frame 38.
As shown in Figure 9, the head of the car-
rousel includes an arm 52 extending radially and mount-
ing a rotating head 54. A second mold member 20 defin-
ing a cavity 24 to form an intermediate sole portion is
mounted to the head 54. A third mold 21 is mounted to
the head 54 by rods 56 at 180 from the second mold 20.
The second mold 20 and third mold 21 can be rotated
between a first position as shown in Figures 1 and 2,
and a second position at a succeeding position on the
carrousel (not shown) with the mold 21 in place as
shown in Figures 3 and 4.
The arm 52 and rotating head 54 is identical
to the structure of the MAIN Group Carrousel low pres-
sure last machine described above. However, in the pre-
sent case, instead of mounting the last on the rotatinghead 54, the head mounts the molds forming the sole.
First mold member 16 further includes a mold
part 60 associated with the mold block 36 as shown in
Figures 1 to 4. This mold part 60 provides a cavity
wall associated with cavity 22 to form the bottom meta-
tarsal inner portion of the upper which extends
inwardly of the last 18. In order not to interfere with
the last 18 and to allow the last to move out of the
cavity 22 as will be described, the mold part 60 can
move away from the mold block 36 as shown in Figure 4,
since it is mounted on the end of a sliding rod 62.
Rod 62 slides in an angled bore 64 in the mold
block 36. The other end of rod 62 is adapted to travel
in a loss motion slot 66 formed on the sub-assembly 38.
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2123D~ 6
Figure 1 shows the molding station in a
position prior to forming a footwear product. In this
case the cylinder 28 and bracket 34 are at their lower
most position. The last 18 is within the cavity 22
while the sub-frame 38, on which the last 18 is
mounted, is at its lowest position seated on the
hooks 44 extending downwardly from the table 25.
The mold part 60 is in its closed position
and the second mold 20 is closed onto the mold
I0 block 36. The cavity 22 with the last 18 is closed and
is ready for the first plastics injection to form the
upper and an intermediate portion of the sole.
In Figure 2 the cycle has been initiated and
the cylinder 28 including bracket 34 have moved
upwardly in the vertical axis.
The injection molding procedure is started
and as shown in Figure 2 the plastics material has been
injected to form the upper and an intermediate portion
of the sole which is delimited by the mold 20. As shown
in dotted lines in Figure 2, the mold 20 will then be
raised. As seen in Figure 9 the arm 52 is mounted to a
carriage 68 which travels on a track 70 formed on the
carrousel. Thus, as shown in Figures 2 and 9, the
mold 20 will be raised a short distance to be released
from the mold 16 and allow the head 54 to be rotated at
180 in order to move the mold 21 into the position
over the cavity 22 of first mold 16. The carrousel will
have rotated the station 10 to the next injection posi-
tion and the mold 21 is then lowered into a position as
shown in Figure 3. A second plastics material of a
different density is then injected to form the sole
onto the intermediate portion of the sole. The second
plastics material may be of a different colour and/or
same density.
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2123~46
As shown in Figure 4 the cylinder 28 con-
tinues its travel, in the vertical axis, moving the
sub-frame 38, and thus the last 18, out of the cav-
ity 22.
However, as the last 18 begins its upward
travel on the rods 40, the mold 21 will have been
removed from the top of the block 36 as previously
described. The upward movement of the sub-frame 38
causes the mold part 60 to be disengaged from the mold
block 36 by means of rod 62. Thus, the last 18 has a
clear path to move upwardly and outwardly of the cav-
ity 22 and allow the footwear product to be demolded
from the last 18.
The only apparent split line is in a hori-
zontal plane at the level of the sole. Thus, any seam
will be coincident with an edge of the sole or other
line demarcation on the upper and, therefore, the split
line or seam is not apparent. It is important that the
separation between the molds and the split line be at
the highest point in order to allow air to escape dur-
ing the molding.
The plastics material flows into the area
between the last 18 and the cavity walls of the mold 21
to form the sole and heel portions. Different colour
and/or different dènsity sole and heel can thus be
integrated on the bottom of the upper.
Although not shown, the head 54 can be piv-
oted 90 to move molds 20 and 21 out of position in
order to allow access to the footwear which is on the
last 18, and the footwear is then removed from the
last. During the demolding of the upper and sole from
the last 18 air can be injected through a nozzle (not
shown) which can be provided on the sole part of the
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2123~6
last 18 to thereby separate the sole of the boot from
the last 18.
The sub-frame 38 is then lowered by retract-
ing the cylinders 28. The weight of the sub-frame 38 on
the bracket 34 should be sufficient to lower the
last 18. However, in the event that sub-frame 38 is
somehow held in suspension, there are springs 32 which
extend between the brackets 34 and the sub-frame 38 to
help move the sub-frame 38 downwardly to its lowest po-
sition as shown in Figure 1. The cycle is then
repeated.
Referring now to Figures 5 through 8 there
is shown a more sophisticated embodiment of the present
invention whereby calf length boots can be molded in
the mold. Some of the corresponding numeral have been
raised by 100 in these figures but they will not neces-
sarily all be referred to. In any event the mold
parts 120, 121 are identical to mold parts 120, 121 in
Figures 1 to 4 and 9, and although the structure mount-
ing the mold parts 120, 121 are not shown it would be
identical to that shown in Figure 9.
The height of mold block 136 is increased
and the cavity 122 is lengthen to include the outer
shape of the calf portion of the boot. From a molding
point of view the calf portion of the boot has greater
dimensions than the ankle portion creating demolding
problems. In the present embodiment, the last 118 has a
second portion 119 which moves independently of
last 118 but in the vertical axis.
A second sub-frame 100 shown in Figures 5
to 8 includes pistons 102 which are within cylindrical
chambers 104 defined in last part 119.
Figure 5 shows the mold parts 116 and 120
or 121 closed onto the last parts 118 and 119. The
-- 10 --
2123û46
plastics material is injected into the space defined
between the cavity walls and last walls to mold a boot.
It is understood that the sequence of mold-
ing the sole as described in respect of Figures 1 to 5
and 9 would be followed in the present embodiment. How-
ever, in Figure 5 the representation of the second mold
is identified by reference numerals 120 and 121 to
indicate that both molds 120 forming the intermediate
portion of the sole, and injected with the plastics
material which is injected to form the upper, can then
be replaced by mold 121 to complete the sole using a
plastics material, preferably of a different density
and maybe of a different colour.
In Figures 6 through 8 mold 121 is identi-
fied.
When it is required to demold the boot the
last 119 is moved downwardly away from the cavity 122
as shown in Figure 6. This is accomplished by the
bracket 134 moving downwardly and drawing rods 102
which move in cylindrical chamber 104 formed in the
last 119. The air 174 is shut so that the cylindrical
chamber 141 and piston 143 are deactivated. In fact air
is provided in the cylindrical chamber 141 above the
piston head of rod 143 when the lasts 118 and 119 are
closed in the mold 116 as shown in Figure 5. This is to
insure a tight closure of the two last portions 118 and
119 .
To allow the last portion 119 to move down-
wardly as shown in Figure 6 the air must be released
from the chamber 141, allowing the piston head of pis-
ton rod 143 to be free of any mechanical connection
with last 119 during its downward movement. Once the
bracket 134 has reached the end of its bottom stroke as
shown in Figure 4 it is then moved upwardly causing the
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rods 102 to move in the loss motion chamber 104 without
- moving the last portion 119. As the bracket 134 engages
the sub-frame 138 by means of bumpers 135 the sub-
frame 138 will begin its upward stroke, pushing the
rod 140 which in turn lifts the last 118 from the cav-
ity 122 as shown in Figure 8. A further upward movement
of the bracket 134 and sub-frame 138 will cause the
last part 119 to return along its upper stroke into the
mold cavity 122. However, by the time the last part 119
reaches its position within the cavity 122 the calf
portion of the boot will have been demolded from the
cavity 122 and the last portion 119. The complete boot
can then be demolded from the last 118.
Once the boot B has been demolded from the
last 118 the bracket 134 and sub-frame 138 are reversed
and start their downward movement to reach a position
as shown in Figure 5. At the same time air is intro-
duced into the cylinder 141 above the head of the pis-
ton rod 143 to positively close the last portion 118
against the last portion 119 within the mold 122. A
second mold 120 is then closed on the opening formed
and the cycle can be repeated.
