Method and an apparatus for assembling and removing a segmented tire mold core in a tire mold

The invention is related to a method of assembling a segmented tire mold core from core segments inside a tire mold, a method of splitting up and removing a segmented tire mold core from a tire mold and an apparatus comprising a tool which determines the outer contour of a tire and a segmented tire mold core which determines the internal contour of a tire, as well as the associated charging, conveying and control devices.

BACKGROUND OF THE INVENTION 
The invention relates to a method of assembling a tire mold core from 
separable core segments inside a tire mold, a method of splitting up and 
removing a segmented tire mold core from a tire mold and an apparatus 
comprising a tool by means of which the outer contour of a tire is 
determined and a segmented tire mold core by means of which the internal 
contour of a tire is determined, as well as the associated charging, 
conveying and control devices. 
It is known to use multiple-part expandable tire mold cores for the 
production of tires. The difference between the expanded and unexpanded 
conditions of such cores is not very great. Using known apparatuses, it is 
possible to produce tires of only small cross sections with small cambered 
heights. Most conventional commerical tires with larger cushion heights 
cannot be produced using these known apparatuses. The occurrence of flags 
of material which make it difficult to remove the core and necessitate 
frequent cleaning of the tool are further critical factors with these 
apparatuses. With known core structures, it is difficult to prevent 
material from penetrating into the openings for the coupling pins and 
movement bolts or between the wedge faces, thus impairing the movability 
of the core.

DESCRIPTION OF THE INVENTION 
The invention is directed to a method of assembling a tire mold core 
comprising: 
(a) moving simultaneously approximately perpendicularly into and toward the 
center of the approximate tire plane containing the radii of the tire to 
be formed, a first unexpanded core segment group; 
(b) radially expanding the first core segment group within the tire plane; 
(c) arresting the expansion of the first core segment group by stopping the 
radial movement of the respective core segments of the group when the core 
segments are positioned so as to partially form a tire mold core; and 
(d) repeating steps (a), (b) and (c) for each remaining unexpanded core 
segment group until the tire mold core is complete. 
The invention is also directed to a method of removing a segmented tire 
mold core from a tire mold comprising: 
(a) moving respective core segments of a first core segment group of the 
tire mold core radially toward the center of the approximate tire plane 
containing the radii of the tire; 
(b) arresting the movement of the core segments of the first core segment 
group when the core segment group is in an unexpanded condition in the 
center of the tire plane; 
(c) moving the core segments of the first core segment group simultaneously 
approximately perpendicularly to and outside of the tire plane; and 
(d) sequentially repeating steps (a), (b) and (c) for each remaining 
expanded core segment group until all core segment groups have been 
removed from the tire plane. 
Additionally, the invention is directed to a method of making tires by 
introducing a segmented tire mold core into a tire mold, forming a cavity 
of predetermined thickness around the completed tire mold core by means of 
a multiple part tire tool which determines the outer contour of the tire 
to be formed, charging the cavity with a tire forming material, opening 
the tire tool after the tire has been formed, removing the tire from the 
tire mold and removing from the tire mold the segmented tire mold core. 
The invention is also directed to an apparatus for making a tire comprising 
a tool by means of which the outer contour of the tire is determined and a 
tire core by means of which the inner contour of the tire is determined, 
as well as the associated charging, conveying and control devices, 
characterized in that the core (1 or 35) comprises segments, the segments 
(1 or 35) are joined toward the center of the tire with a guide and an 
adaptor member (21 or 36), said segments (1 or 35) being radially movable 
in groups approximately in the plane of the tire and said segments also 
being movable approximately perpendicularly to the plane of the tire in a 
position at the center of the tire. 
Objects of the invention are generally to produce high quality tires 
economically and particularly to reduce the cycle times by automating the 
introduction of a core into the tire tool and removing the core in the 
tire tool in a practical manner. High demands are placed on the apparatus' 
non-susceptibility to failure. 
These objects are achieved by the apparatus in that the core comprises 
separable core segments, each of the core segments is joined toward the 
center of the tire with a guide and adaptor member; the core segments can 
be moved radially in core segment groups approximately in the tire plane 
and also can be moved approximately perpendicularly to the tire plane 
while in a position in the center of the tire. When assembling the tire 
mold core, the core segments are introduced in unexpanded core segment 
groups into the center of the approximate tire plane containing the radii 
of the tire to be formed, are expanded radially in core segment groups, 
and are arrested in their terminal positions forming the mold core. When 
splitting up the mold core, the core segments are moved in core segment 
groups toward the center of the tire, and then are moved in these core 
segment groups approximately perpendicular to the tire plane and into a 
plane outside the approximate plane of the tire. 
In particular, high quality tires can be produced by this method from 
pourable elastomers. The method is so flexible that most commercial tires 
can be produced having conventional tire widths, tire diameters and 
cushion heights. 
It is also particularly desirable that the filling operation can take place 
from the center. In the assembled condition, the core does not have any 
inconvenient structural components toward the center of the tire and has a 
very smooth internal surface. Whether the tire is formed by injection 
molding or by centrifuging is of secondary importance in the invention. 
The method is not only suitable for the production of an integral tire but 
it is also possible to produce a ready-made or partially-made tire on the 
stable core and to compress tires which have been made beforehand by, for 
example, vulcanization. Both pourable and injectable elastomers or 
vulcanizable elastomers can be processed on the apparatus of the 
invention. 
The tire mold core is very stable in shape and position. It can be 
mechanically dismantled and assembled in the mold in a short time. 
Undisturbed operation is guaranteed for long periods due to the simple 
radial movement of the core segments approximately in the plane of the 
tire. 
The preferably metallic core produces a smooth internal surface. The core 
segments can be guided and arrested so accurately to form a smooth, 
circular internal surface that tires which can run concentrically with 
high accuracy are obtained. Over-dimensioning of the wall thickness for 
reasons of safety can be omitted due to the high precision possible during 
production. 
There are ventilation slits either unavoidable or intentional on the mold 
core. If material should penetrate into these slits, the ability to split 
up the core is not placed in doubt. Production is possible without 
bladders. 
Each of the core segments has a guide and an adaptor member toward the 
center of the tire. During removal of the core, the core segments first 
are moved radially toward the center of the tire plane and then guided 
axially through the internal diameter of the tire and mold and out of the 
separating plane of the mold. The core segments are usually shifted to the 
central point of the tire plane with the aid of a lifting element group. 
All core segment groups can be moved with one lifting element group if it 
is mounted pivotally. During the lifting stroke, the guide members of the 
core segments slide from the guides in the outer mold into the guides of a 
take-up platform which is positioned in the center. The take-up platform 
and its associated core segment group is lowered axially and then moved, 
for example, in a linear direction. The next free take-up platform is 
positioned in the take-up position so that the next core segment group can 
be removed from the mold. A course of movement of this type which takes 
place on linear or simple geometric (circular) paths is rarely susceptible 
to breakdown. In known apparatuses, the three-dimensional course of 
movement is quite complicated. By the invention, precise positioning of 
the core segments is possible, even over long operating times, due to the 
simple and inexpensive guides in conjunction with stops and controlled 
lifting elements. 
Further stabilization and clamping of the core segments is provided by the 
cut guide between the core separating planes which always are 
perpendicular to the tire plane. The simple geometric shape of the core 
segments is desirable for reasons of production. 
The core can be heated in the same manner as the mold so that vulcanizable 
compositions can also be pressed on to the core with close tolerances in 
the wall thickness and can then be processed. 
It may be necessary to evacuate the mold prior to casting. The method of 
the invention does not give rise to any particular problems at this stage. 
The channels can run between or within the core segments, for instance by 
countersinks into the core separating plane. 
The core separating plane preferably runs radially or almost radially. 
These planes are perpendicular to the tire plane. It is advantageous, for 
example, if the core segments which are removed from the core first and, 
therefore, reinserted last are designed slightly wedge-shaped toward the 
external diameter. This makes access easier as the core is split up and 
allows the core segments to be clamped in the expanded condition. 
A group of segments is moved simultaneously in each case in a preferred 
range of from three to six times for about each two to six parts. This 
reduces the cycle time considerably. 
The invention is illustrated in the drawings by way of example and is 
described in more detail below. 
In these examples, the core 1 is divided into 16 segments which are 
combined into four groups. The allocation of the segments to a group is 
clarified by the addition of the letters a, b, c and d. In FIG. 1a, the 
first core segment group 1a is moved from its position in the mold core to 
the center of the tire leaving groups 1b, 1c and 1d still in the expanded 
condition. The core segments 1a are then moved radially to the center of 
the tire and then out of the tire plane. FIG. 1b illustrates a condition 
in which the second core segment group 1b has been moved from the expanded 
condition and into the center of the tire. It, too, is then moved out of 
the tire plane. The core segments (for example, 1a and 1b) are 
approximately disc-shaped. They are preferably tapered in a slightly wedge 
shape in the outward direction. In FIG. 1c, only the last core segment 
group 1d remains in the expanded condition while the group 1c has been 
moved to the center. In FIG. 1d, core segment group 1d has been moved from 
the expanded condition into the center of the tire plane, all other groups 
already having been removed from the tire plane. The last core segment 
group 1d need no longer be moved from the plane of the tire in FIG. 1d as 
it can be the fire core segment group to be moved back into the mold core 
position when the mold core is reassembled. 
FIGS. 2 to 8 and 9 to 13 show two different embodiments of the apparatus of 
the invention. FIG. 2 shows a section through an apparatus from the side 
with press, tool and core removing unit (FIG. 2 (7). The upper section of 
the mold 2 is raised. The tire 3 cannot yet be removed in this position. 
As seen from the lefthand region, at least one core segment group 1 is 
also present in the tire 3. In addition, the outer mold segments 5 are 
still engaged. The outer mold segments 5 are drawn outwards by the claws 6 
and the tire 3 is released only when the upper section of the mold is 
raised further. 
The assembly and dismantling of the segmented tire core 1 is made clearer 
in FIG. 3. Each of the core segment groups 1a, 1b, 1c and 1d is deposited 
on its own lifting platform 7. The segment groups are designated 
respectively 1a, 1b, 1c and 1d to distinguish which segment group belongs 
to which lifting platform (7a, 7b, 7c and 7d). In FIG. 3, three core 
segment groups have already been removed. The lifting platform 7d is 
raised and the core segments 1d which are still located in the tire 3 can 
be moved to the center of the tire by the lifting elements 8 (further 
illustrated in FIG. 4). The lifting elements 8 obviously also move the 
core segments from the center of the lifting platform into the mold core 
position in the same way. The four lifting elements 8 (shown in FIG. 4) 
are located on a rotating table 9 (FIGS. 3 and 4) which is adjusted by a 
geared motor 10 (FIGS. 2 and 4) so that they can move all core segment 
groups 1 (FIGS. 3 and 4). 
After the mold core has been split up, the core segments can be expanded in 
the reverse sequence to again form the mold core. As can be seen from 
FIGS. 3 and 4, the lifting platform 7d with the core segments 1d, which 
are shown still in the expanded condition, obviously need not be lowered 
by the lifting device 11 (FIG. 3) when the core segments 7d are moved to 
the center and the tire is removed. As the core is reassembled, core 
segments 1d are moved back into the mold core position first, as shown in 
FIGS. 3 and 4. The empty lifting platform 7d is lowered. The advancing 
movement of the lifting cylinder 12 (FIGS. 3 and 4) will then move the 
core segment group 1c on the lifting platform 7c beneath the tire tool. In 
the meantime, the lifting elements 8 on the rotary platform 9 will also 
move into the coupling position required for the core segments 1c. The 
couplings 23 on the core segments 1 are shown more clearly in FIGS. 7 and 
8. The lifting elements 8 move the core segments 1c into their expanded 
position after they have been raised on the lifting platform 7c into the 
plane of the tire. The remaining core segments 1b and 1a are also inserted 
in the same way. The mold ring 13 is raised by the raising element 14 
(FIGS. 2 and 3). Foot rings are needed in most tires. In the method of the 
invention, the lower foot ring 15 is inserted when all core segments 1 
have moved to the center of the tire plane. The upper foot ring 16 is 
inserted once the core 1 has expanded before the mold is closed by the 
press 17 (FIG. 2). As can be seen from FIGS. 2 and 5, as the mold tool is 
closed, the outer mold segments 5, the upper section 2 of the mold and the 
mold plate system 18 are moved into the production position. In so doing, 
the mold plate system 18 takes over the locking of the core segments 1 and 
seals the mold in the center. The remaining cavity is filled by means of 
the end unit 19 (FIG. 2) of the dosing device which is usually a mixing 
head. A tire is then formed which receives its final shape due to both the 
contour of the tool (2, 5, 13 and 22) and the internal core segments 1 
forming the mold core. 
Once reaction or vulcanization is complete, the core is split up in the 
reverse sequence as just described, i.e. the core segment group 1a which 
was mounted last is drawn on to the lifting platform 7a first. The mold 
ring 13 has to be lowered before the core is dismantled. 
In FIG. 4, core segment groups 1a, 1b and 1c on the lifting plates 7a, 7b 
and 7c are located in the lowered position to the side of the tire tool. 
The core segments 1d are moved into the expanded position. 
In FIG. 5, the tire mold is completely compressed. It can be seen that a 
reinforcement 4 is provided in the running tread of the tire in addition 
to the foot rings 15 and 16. These reinforcing inlays are placed in the 
mold at the same time as the lower foot ring 15 when the core has been 
split up. As illustrated in FIGS. 7 and 8, there are usually holding combs 
20 on the core segments. 
FIG. 6, which is a view approximately perpendicular to the plane which 
would contain the radius of the tire, shows the segments in the production 
condition without press and without mold. 
An individual segment of group 1a or 1b with combs 20 is illustrated in 
FIGS. 7 and 8. 
FIGS. 9 to 13 show another embodiment of the apparatus of the invention. 
Unlike the previous apparatus, in this example the tire axis extends 
horizontally. This apparatus is preferably used for making up and 
compressing elastomers. It is also particularly suitable for vulcanizing 
ready-made rubber tires. The core is readily accessible. It is simple and 
fast to assemble due to its small number of components. This core removal 
unit is very suitable for rotational casting. The core unit is suitable 
for making up tires without an outer mold, for example Numbers 30, 31 and 
32 in FIG. 9. 
Whereas in the first embodiment the core segments moved in the plane of the 
tire or parallel to the plane of the tire in the first step of the 
operation for splitting up the core, in this embodiment the path of the 
core segments is circular. However, as suggested by FIG. 10, since the 
radii are relatively large in comparison with the path, the core segments 
remain approximately in the plane of the tire. 
Whereas the tool parts 2, 5, 13 and 22 shown in FIGS. 2 to 5 correspond to 
the tool which determines the outer contour of the tire in the first 
embodiment discussed, parts 30, 31 and 32 shown in FIGS. 9 to 13 determine 
the outer contour of tire in the second embodiment. FIG. 9 shows the tool 
in the production position. Once the tire material has fully reacted, the 
central locking plate 34 will move to the right. 
FIG. 10 shows the first core segment group 35a. The lateral dishes 30 and 
32 are open and the moldings 31 are raised in the radial direction. The 
core segments 35 are joined to hinge arms 36. They can be pivoted about 
the hinge axis 37 toward the center of the tire mold over a circular path. 
In FIG. 11, the tool with the outer moldings 30 and 31, including the core 
segment groups 35b, 35c and 35d which have not yet been moved into the 
center of the tire plane, will travel by about one tire width to the 
right. The core segment group 35a which has already been withdrawn remains 
in its position and is portrayed by broken lines. In this position, the 
core segment group 35b is dismantled by lifting elements. These lifting 
elements which are not shown in FIG. 11 are located between the hinge arms 
36a of the core segments 35a which have already been removed from the 
mold. 
FIG. 12 shows the next step of removal from the mold. The core segment 
groups 35a and 35b which have been pivoted away by their pivoting the 
guide bearings and the open segmented outer mold (Numbers 31 and 30) 
remain in their position while the other external mold dish 32 with the 
tire 33 and the remaining core segments 35c and 35d travel by about two 
tire widths to the left from their position in FIG. 11. There, core 
segment group 35c is removed. 
As the last stage, the outer ring 32 of the mold with the core segment 
group 35d including mounting 37 is moved once again by about one tire 
width to the left and the last core segments 35d are pivoted to the 
central point of the tire. The tire 33 can be removed through the opening 
formed between the outer moldings which were moved to the right and to the 
left and the core segment groups. The core is assembled in the reverse 
order. 
If tires are to be made up separately, the outer mold (30, 31 and 32) is 
replaced by centering rings which, in conjunction with the locking plate 
34 of FIG. 9 ensures that the core segments 35 are centered.