Note: Descriptions are shown in the official language in which they were submitted.
69~
Background of the Invention
The invention is concerned with a molding apparatus
for finish forming and curing tread and track belts with any
desired tread pattern thereon.
In the making and curing of tire tread and track belts
it has been common to wrap one or more layers of an uncured
elastomeric material such as rubber or the like, with or with-
out reinforcement such as metal belting, fabric and the like,
about a cylindrical core. The cylindrical core is selected
to have a diameter equal to the desired inner diameter of the
eventually cured belt. Thereafter, the cylindrical core,
with the elastomeric layers and the like attached thereabout,
is generally placed in the center of a cylindrical mold which
comprises a larger cylinder, which larger cylinder can include
mold faces with desired tread patterns on the interior sur-
face thereof, the diameter of the larger cylinder is reduced
until it properly contacts the material wrapped about the
inner core and the entire apparatus is heated to cure the
elastomer wrapped about the inner core. In such an apparatus,
the outer mold face cylinder can, of course, be constantly
heated if desired but it is not possible to heat the inner
core about which the rubber is wrapped because premature
curing might then take place. What results is somewhat un-
even heating and hence uneven curing of the elastomer into
the form of a tire tread or track belt. In particular, metal
bands within the tire tread or track belt are often displaced
from their desired positions when cured in a prior art mold
with a relatively high temperature gradient between the inner
core holding the tire tread or track
-- 1 --
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belt and the outer cylinder of mold faces. Also, the time of
curing is relatively long since the inner core, at least,
must be heated after it has been placed in the mold. Further,
the repeated heating and cooling of at least the inner core is
costly in energy.
It would be highly desirable to provide an apparatus
and a process for curing tire tread and track belts wherein
the belts were uniformally and relatively ~uickly cured from
both their inner and outer circumferences while heating costs
were minimized and wherein metal bands and the like within the
tire tread and track belts were kept uniformally distributed
by the uniform curing thereof. The present invention provides
~, jus~ a~ apparatus and process.
Summary of the Invention
The invention comprises an apparatus for curing a
tread or track belt, said apparatus having a plurality of
~ inner segments movable between a first position at which the
-~ inner segments fit together to form a substantially inner
cylindrical mold face surface and a second position at which
the inner segments are moved radially inwardly toward a
longitudinal axis of said cylindrical mold face surface, said
plurality of inner segments including a first set of inner
segments alternatively placed between the segments of a second
set of inner segments, the improvement comprising: means for
moving the segments of the first set of inner segments between
the first and second positions; means for moving the segments
of the second set of inner segments between the first and second
position in response to movement of the segments of the first
set of inner segments; a plurality of outer segments movable
between a first position at which the outer segments fit
together
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to form a second mold face surface and a second position
at which the outer segments are moved radially outwardly;
means for moving the outer segments between the first and
second positions; a seal ring movable between a first posi-
tion at which said seal ring is in sealing contact with theends of inner and outer segments at the first position of the
inner and outer segments and a second position at which said
seal ring is positioned intermediate to the ends of the inner
and outer segments at the second position of said inner and
outer segments; and means for moving the seal ring between
said first and second positions.
Brief Description of the Drawings
.
The invention will be better understood by reference
to the drawings wherein like numbers denote like parts
: 15 throughout and wherein:
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-- 3 --
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FIG. 1 illustrates in top view an apparatus in
accordance with the present invention for curing tire tread
and track belts;
FIG. 2 is a view taken along the plane II-II of FIG. l;
. 5 FIG. 3 illustrates a blown-up partial view taken
: along the plane III-III of FIG. 1 showing a track belt within
the apparatus of the present invention;
FIG. 4 illustrates a blown-up partial view similar
. to that of FIG. 3 but with a tire tread belt within the
apparatus of the present invention;
FIG. 5 illustrates a blown-up view taken in the area
V of FIG. l;
FIG. 6 illustrates a blown-up cross section of a
facing member of an outer mold shoe for a track belt;
FIG. 7 illustrates a blown-up cross section of a .
facing member of an outer mold shoe for a tread belt; and
FIG. 8 illustrates a blown-up detail relating to
coordinated movement of the outer mold shoes for a tread or
track belt.
Description of the Preferred Embodiment
A tire tread and trackbelt curing apparatus 10 is
shown generally in FIG. 1. FIGS. 2 - 8 show details in the
structure of said preferred apparatus 10. The apparatus 10
includes an inner cylinder 12 formed partially of a first
set of a plurality of inner segments 14. The first set of
inner segments 14 each fit adjacent to one another, as shown
most clearly in FIGS. 1 and 5, to form the inner cylinder 12.
The inner cylinder 12 is further formed from a second set of
a plurality of inner segments 15 which, in a manner which will
be described in following, act as slave segments
~ 4 --
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which are carried forward by the movement of the first set of
inner segments 14, which segments 1~ are powered. Thus, the
first set of segments 14 and the second set of segments 16 fit
together in alternating sequence to form the inner cylinder 12.
As will be noted by reference to FIG. 5, it is necessary that
the inner cylinder 12 be completely continuous. That is, gaps
cannot be left between adjacent inner segments 14 and 16, and
a proper mechanical arrangement must be provided to give an
easy and smooth working mechanism whereby the first plurality
of inner segments 14 and the second plurality of inner seg-
ments 16 can be easily retracted and advanced to form the con-
tinuous inner cylinder 12 in the manner described below.
FIG. 1 does not show fully the mating of the inner segments 14
and 16 to form the continuous inner cylinder 12 because of
crowding problemsO FIG. S illustrates this feature in detail,
as explained below.
Retraction of the first set of segments 14 proceeds
via action of a first plurality of links 20 under the impetus
of an elevation cylinder 22 which is moved upwardly or downwardly
under the impetus of a first hydraulic cylinder 24. The first
hydraulic cylinder 24 acts between a frame 26 and the elevation
;~ cylinder 22 to cause the elevation cylinder 22 to move up-
wardly or downwardly as guided by a centering slide 28 which
forms a part of the frame 26. As will be most apparent from
FIG. 2, there is a second plurality of links 30 aligned below
the first plurality of links 20 in one-to-one relation
therewith so as to provide an even pulling or pushing force up-
on the tops and bottoms of the first set of inner segments 14
and, as will be explained later, also upon the second set of
inner segments 16. Each of the links 20 is pivoted at a
plurality of first pivots 32 to the
1~ 4
elevation cylinder 22. In the embodiment illustrated, the
elevation cylinder 22 is at its lowermost position under the
impetus of the hydraulic cylinder 24 which is substantially
fully retracted and in that position each of the first
plurality of links 20 and the second plurality of links 30 is
substantially horizontal thus holding the first powered set of
segments 14 in their outwardly expanded position to form the
continuous inner cylinder 12.
Referring most particularly to FIG. 2, it will be
noted that a second hydraulic cylinder 36 communicates be-
tween the frame 26 and a linkage 38 to provide a capability
for moving upwardly and downwardly a lower seal ring 40.
The lower seal ring 40 along with the inner cylinder 12, an
upper seal ring 42 and an outer cylinder 44 together form
the basic structural parts of the apparatus 10 of the present
invention. It is clear that as the second hydraulic cylinder
36 expands, i.e., as a rod 46 thereof extends therefrom, a
horizontal block 48 will be forced downwardly thereby pulling
downwardly at a plurality of pivots 50 upon a plurality of
links 52, which in turn pull downwardly at a plurality of
pivots 54 upon a plurality of cranks 56, which are centrally
pivoted at a plurality of pivots 58 to a plurality of
stationary arms 60 which extends downwardly from and forms
a part of the frame 26. The downward force exerted upon the
pivots 54 results in an upward force exerted upon a plurality
of links 62 at a plurality of pivots 64. This in turn leads
to a force being upwardly applied upon the lower seal ring
40 via a plurality of pivots 66 and an intermediate lower
seal ring support 68.
Referring most particularly to FIGS. 1 and 2, there
is illustrated therein the upper seal ring 42 previously
-- 6 --
; mentioned and means for lifting it upwardly and away from the
inner cylinder 12 and the outer cylinder 44, and then tilting
it to a generally vertical position. Briefly, the upper ring
seal 42 is held by a lift fixture 70 which communicates via
- 5 a bridge 72 and a link 74 with lift means 76, said lift means
76 comprising a third hydraulic cylinder 78 and a crank 80.
The third hydraulic cylinder 78 is attached to a portion of
the frame 26 radially external of the outer cylinder 44.
~enerally, the third hydraulic cylinder 78 is attached to the
frame 26 at pivot 82. The third hydraulic cylinder 78 has a
: rod 84 forming a part thereof in the usual manner, and the
rod 84 is attached pivotally to a pivot 86 to the crank 80.
The crank 80 is pivotally attached to the frame 26 at a
pivot 88 and is also attached to the lift fixture 70 at a
pivot 90. As the hydraulic cylinder 78 extends, thus causing
the rod 84 to move outwardly therefrom the crank 80 is forced
to pivot about the pivot 88 thereby causing an upward force
upon the pivot 90 and an overall lifting force upon the lift
fixture 70. At the same time, an auxiliary hydraulic cylinder
92 would have its rod 94 extending outwardly and acting via
a pivot 96 to provide an overall vertically upward movement
of the lift fixture 70. What results then is a direct vertical
upward movement of the lift fixture 70 with the link 74 rotat-
ing about a pivot 98 that is attached to the frame 26 and
about a pivot 100 that is attached to the lift fixture 70.
After the lift fixture 70, and with it the upper seal ring
; 42, has been moved upward directly a sufficient distance to
clear any obstructions, the lift fixture 70 is then rotated,
as by retraction of the third hydraulic cylinder 78, and the
auxiliary hydraulic cylinder 92 to move pivotally away from
the top of the apparatus 10 and into a vertical position.
-- 7
i
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It is important to the practice of the present invention,
especially when a track belt 102 is being cured therein, that
it be possible to lift the upper seal ring 42 directly upwardly
so that it may clear the anchor plates 104 thereof, as is
illustrated most clearly in FIG. 3. It will be apparent tha-t
the link 74 along with the crank 80 forms an unequal parallel
arm linkage that is powered by the third hydraulic cylinder 78.
The linkage is thus arranged so that the lift fixture 70 raises
` the upper seal ring 42 approximately straight up during the
initial extension of the third hydraulic cylinder 78. As
will be further noted by reference to FIGS. 1, 2, 3 and 4,
a plurality of holddown plates 105 extend from the first
plurality of cylinders 14 radially outwardly to rest upon and
ho]d down the upper seal ring 42 when it is in its down
(sealing) position. This increases the overall structural
integrity during belt curing.
Referring now once again most particularly to
FIGS. 1 and 2, there is illustrated therein in some detail the
structure and operation of the outer cylinder 44. Briefly,
the outer cylinder 44 comprises a plurality of outer segments
106, each of which is retractable outwardly under the impetus
of a respective one of a plurality of outer hydraulic cylinders
; 108, with each of the plurality of outer segments 106 being
generally carried by a rod 110 of a respective one of the
outer hydraulic cylinders 108, and with each of the segments
of the plurality of outer segments 106 being slidingly held
and positioned between a respective guide 112 supported by
, the frame 26. Thus, each of the third plurality of segments
106 is constrained to move horizontally. Each of the outer
cylinders 108 is held by an outer ring portion 114 of the
frame 26.
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- Referring now to FIGS. 6 and 7, there ~ llustrated
therein embodiments of the plurality of outer segments 106
adapted respectively for forming track belts and tread belts.
` In each of these two embodiments, passages 116 are provided
within the outer segments 106 to allow them to be kept at
a desired curing temperature. Thus, the outer segments 106
can be preheated to a desired curing temperature Eor the
- belt which is to be cured within the apparatus 10. A
plurality of facing members 117, which in some cases, as
discussed in following, may define a tread pattern, are
affixed removably as via bolts one to each of the outer seg-
ments 106.
The embodiment of FIG. 6 is concerned with a track
belt and hence generally there will be no tread pattern therein
other than a pattern for mating with a traction shoe bolted
to the track belt. Instead, there will generally be a
reinforced high temperature elastomeric cup 118 which acts
as a plug to abut each central boss 120 in each anchor plate
104 of a track belt. The cup 118 is made of an elastomeric
material so that it will deflect inwardly thus sealing and
assuring a clean outer surface about the central boss 120
in the anchor plate 104. This facilitates later attachment
of traction shoes to the belt after it is cured.
Turning now more particularly to FIG. 7, there is
shown therein a cross section of one of the facing members
117 for a tread belt. With the tread belt, each of the facing
members 117 will generally include a series of upraised
ridges 122 defining a tread pattern. As with the embodiment
in FIG. 6, the passages 116 serve as steam passages whereby
the facing members 117 can be kept at a constant curing
temperature.
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The inner cylinder 12 is generally also heated by
passing steam or the like into the interior of the first set
of inner segments 14, and more particularly into a plurality
of steam chambers 124 therein, illustrated in FIG. 2.
Similar steam chambers can be provided within the second set
of inner segments 16.
Reference to FIG. 5 will illustrate the interaction
between the first set of inner segments 14 and the second
set of inner segments 16 as driven by the first and second
pluralities of links 20 and 30. The upper seal ring 42 is
shown in FIG. 5 in partially cut-away form whereby the join-
ing together of the first set of inner segments 14 with the
second set of inner segments 16 to form the inner cylinder
; 12 as a complete cylinder is clearly illustrated. As will be
noted from FIG. 5, each of the second or slave set of inner
segments 16 is locked in place by an edge 126 on the first
set of inner segments 14 which mates with a ledge 128 on
each of the second set of inner segments 16 to form a joint
129. Thus, any force exerted inwardly upon one or more of
the second set of inner segments 16 causes the ledge 128 to
be forced against the edge 126 and, since the edge 126 is
poweredly held in place by the first and second pluralities
of links 20 and 30 and the operation of the elevation cylinder
22, each of the second set of inner segments 16 is also held
in place in the same manner.
During retraction of the first set of inner seg-
ments 14 toward the elevating cylinder 22, as when the first
` hydraulic cylinder 24 extends whereby the first and second
links 20 and 30 are pulled upwardly at the first plurality of
pivots 32 and the second plurality of pivots 34, thus pulling
the first set of inner segments 14 toward the elevation
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cylinder 22 at a third plurality of pivots 130 and a fourth
plurality of pivots 132, respectively, the fi.rst set of
inner segments 14 is linked to the second set of inner
segments 16 by a plurality of slotted master/slave links 134
which are rotatably attached to the first set of inner seg-
ments 14 at a i~t~ plurality of pivots 136 and to the second
set of inner segments 16 via a sixth plurality of pivots 138.
The links 134 are slotted at the fifth plurality of pivots
136 to correct for possible machining variations. The fifth
plurality of pivots 136 are attached to the first set of
inner segments 14 at a plurality of arms 140, which extend
therefrom toward the elevation cylinder 22 intermediate the
; first plurality of links 20 and the second plurality of links
30. As is clear, most particularly by reference to FIGS. 2
and 5, as the first plurality of links 20 and the second
plurality of links 30 are caused to move upward under the
impetus of the elevation cylinder 22 moving upward at the
pivots 32, 34 respectively, the first set of inner segments 14
is forced to move inwardly as the first plurality of links 20
pivot about the third plurality of pivots 130 and the second
plurality of links 30 pivot about the fourth plurality of
pivots 132. This causes the plurality of master/slave links
134 to pivot about the fifth plurality of pivots 136 which
~ in turn causes the sixth plurality of pivots 138, motivated
; 25 by the plurality of master/slave li.nks 134, to pull inwardly
upon the second set of inner segments 16. Thus, first the
first set of inner segments 14 pull away from defining the
inner cylinder 12 and then the second set of inner segments
16 follow the first set of inner segments 14 away from
forming the inner cylinder 12. In actual design, the link
-- 1 1 --
." ' " ~ .
134 and its connections to the first set of inner segments
14 and the second set of inner segments 16 is generally chosen
so that the first set of inner segments 14 will travel away
from the inner cylinder 12 approximately twice the distance
that the second set of inner segments 16 will travel away
from said inner cylinder 12. The design objective is to get
inner cylinder 12 to retract far enough to allow lower ring
40 sufficient clearance to elevate. The 2:1 travel is a result.
Turning now to FIG. 8, there is illustrated therein
means for assuring that each of the outer segments 106 travels
outwardly away from defining the outer cylinder 44 at a
generally equal rate even if one or more of the hydraulic
cylinders 108 does not tend to operate at exactly the same
speed as do all of the other cylinders 108. More particularly,
FIG. 8 illustrates a segment alignment mechanism 144 comprising
a first bore 146 within one of the segments 106 and a second
bore 148 within the next adjacent of the segments 106. A
shaft 152 fits in pressed fit within the first bore 146 and
its loosely within the second bore 1~8. Also within the
second bore 148 is a spherical bearing 154 in which the shaft
152 slidingly fits. Thus, i one o the two adjacent shoes
106, shown in FIG. 8, tends to be moved by its respective
hydraulic cylinder 108, at a different rate than the other
shoe segment 106, the shaft 152 extending therefrom will
exert pressure upon the slower-moving adjacement segment 106
whereby they will be forced to travel at the same speed. The
' spherical bearing 154 in this case serves to allow for varia-
tions and to prevent binding and the like.
` Adverting now once again to FIG. 3, there is
illustrated therein a particular upper seal ring 42 and upper
- 12 -
seal ring arrangement which is useful when a track belt 102,
having anchor plates 104 thereon, is secured in the apparatus
10 of the invention. When track belts 102, which have anchor
plates 104, are to be secured in the apparatus of the present
invention, then a speclal problem arises of obtaining a good
seal about the anchor plates 104 and maintaining that good seal
during securing of the track belts 102. One advantageous
apparatus for accomplishing this is shown in FIG. 3. In this
apparatus, the first set of inner segments 14 or the second
set of inner segments 16, as the case may be, and at times
the joining of the first set of inner segments with the
second set of inner segments, as shown for example in FIG. 5,
meet to form the inner cylinder 12. The upper seal ring 42
adjacent the anchor plates 104 would then preferably include
a pin 156 loaded by a spring 158 to protrude inwardly toward
the elevation cylinder 22 until a pressure pad 160 contacts
an inner end 162 thereof, and presses the pin 156 against the
force of the spring 158 sufficiently so that an outer end 164
thereof contacts the anchor plate 104 and holds it in its
- 20 proper radial position.
In order to maintain the apparatus 10 easily con-
vertible for handling either track belts or tread belts,
an end portion 166, 167 of each of the outer segments 106 is
made detachably attachable thereto. Thus, one can convert
from the configuration shown in FIG. 3 to the configuration
shown in FIG. 4 by changing the upper seal ring 42 and by
changing the end portions 166, 167 of each of the outer
segments 106. End portion 167 useful with the track belt 102
; is pinned by press fit pins 176 shown in FIG. 3 to the anchor
plates 104 with two pins 176 each being used at the top and
bottom of each anchor plate 104.
- 13 -
.
The pins 176 are piloted in mounting holes to keep the anchor
plates 104 in proper alignment during cure. A change in the
upper seal ring 42 is necessary with respect to the first set
of inner segments 14 and/or the second set of inner segments
16 for which purpose an end portion 168, 169 thereof is
likewise made detachably attachable.
It should be noted that each of the structures
shown in FIGS. 3 and 4 represent changes made not only at the
upper seal ring 42 but also represent changes which are made at
the lower seal ring 40, symmetrically thereto. A seal member
170 is provided which abuts the right hand curved portion of
` the anchor plates 104. The seal member 170 is clamped beneath
the end portion 167. Another seal member 171 is held in the
: upper seal ring 42 and abuts the left hand curved portion
of the anchor plates 104. At the edges of the plates 104 the
two seal members 170 and 171 meet each other. Between the
;~ anchor plates 104 the seal member 171 extends to abut the
facing members of the third plurality of segments 106. The
seal members 170 and 171 contact at an angle as illustrated
at X at the edges of the anchor plates 104. This allows the
` pressure of flowing uncured rubber of the belt 102 to aid in
sealing the joint between the seal members 170 and 171. Once
again, identical structure is needed for the lower seal ring
40. It should be noted further by reference to FIG. 4 that
the upper seal ring 42, and for that matter the symmetrical
` lower seal ring 40, is heated as via passing steam through
the steam chamber 172 therein.
Operation
In operation with the first set of inner segments 14
and the second set of inner segments 16, as well as the plural-
ity of outer segments 106, retracted away from forming the
- 14 -
respective inner cylinder 12 and outer cylinder 44, the linkaye
38 is activated by the second hydraulic cylinder 36 to cause
the lower seal ring 40 to move upwardly. An uncured belt 11 is
then placed upon the lower seal ring 40 and it is lowered into
place through shortening of the second hydraulic cylinder 36
and concurrent movement of the linkage 38. Thereafter, the
upper seal ring 42 rotates from the vertical to the horizontal
and lowers into position under the impetus of the hydraulic
cylinders 78 and 92. At this time, the belt 174, if a tread
belt, or 102, if a track belt, is held between the lower seal
ring 40 and the upper seal ring 42. The first set of inner
segments 14 then begins moving outwardly and carries the
second set of inner segments 16 outwardly with it. Inner
cylinder 12 is formed completely before outer segments 106 be-
gin to move inwardly. Outer segments 106 then move in untilthey are resisted by the uncured rubber. The hydraulic cy-
linders 108 are large enough to create a pressure, generally
at least 200 psi and preferably about 350 psi in the uncured
rubber between the inner cylinder 12 and the outer cylinder 44.
This is an important aspect in making a good belt.
During this entire operation, the first set of
inner segments 14, the second set of inner segments 16 and the
plurality of outer segments 106 are maintained and preheated as
by steam flowing through the passages 116 and 124 at a tempera-
ture suitable for curing the belt 102 or 174. The apparatus
is then held in its closed position until the belt 102 or 174
has become cured. Thereafter, the outer plurality of segments
106 are withdrawn, the first set of inner segments 14, followed
by the second set of inner segments 16, are withdrawn and the
upper seal ring 42 is lifted from the belt 102 or 174 and the
- 15 -
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lower seal ring 40 is elevated through action of the second
hydraulic cylinder 36 and the linkage 38 to push upwardly the
now-cured belt 102 or 174 and place it in position for removal
so that another uncured belt 102 or 174 can replace it.
Wh le the invention has been described in connection
with specific embodiments thereof, it will be understood that
it is capable of further modification, and this application is
intended to cover any variations, uses or adaptations of the
invention following, in general, the principle.s of the inven-
tion and including such departures from the present disclosure
as come within known or customary practice in the art to
which the invention pertains and as may be applied to the
essential features hereinbefore set forth, and as fall within
the scope of the invention and the limits of the appended claims.
.
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