Note: Descriptions are shown in the official language in which they were submitted.
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VULCANIZATION MOLD AND PNEUMATIC VEHICLE TIRE
Field
The invention relates to a vulcanization mold for vulcanizing a pneumatic
vehicle tire, in particular
a passenger vehicle winter tire, having mold segments which form the profiled
tread strip of the
tire and have mold webs which form depressions for forming profile blocks or
block-like profile
positives, lamellar plates for forming sipes in the profile blocks and/or
block-like profile positives
being anchored in depressions, the lamellar plates dividing the depressions
into portions, in which
in each case at least one ventilating bore is configured in the mold segment.
Furthermore, the
invention relates to a pneumatic vehicle tire which has been heated in a
vulcanization mold of this
type.
Background
During shaping of a green tire into a vulcanization mold, the air which is
present in the
vulcanization mold is enclosed between said mold and the green tire and has to
be discharged.
It is therefore customary to ventilate vulcanization molds by a multiplicity
of ventilating bores being
configured which ensure discharge of the enclosed air. Ventilating units with
valves are usually
inserted into ventilating bores, which ventilating units close the ventilating
bores when the green
tire has been shaped and therefore prevent the generation of rubber flash
during the vulcanization
of the green tire. In the case of tread strip profiles which are formed by way
of profile blocks and/or
block-type profile positives, it is customary to position the ventilating
bores at the lateral edge
regions of the depressions which form the blocks and/or the block-like profile
positives. If lamellar
plates are provided which form narrow sipes in the blocks and/or profile
positives, in each case
two ventilating bores are usually provided per portion. In the case of long
depression portions, in
each case one central ventilating bore can additionally also be provided. If
the enclosed air is then
not discharged completely, irregularly shaped block element edges can be
produced, in particular
in the region of the sipes which are formed by the lamellar plates.
Summary
The invention is based on the object of configuring a vulcanization mold in
such a way that the
block and sipe edges are formed exactly, with the result that the block edges
and sipes which are
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formed in the tread strip can develop their effect which is required for
optimum snow and ice
performance.
According to the invention, the object which is set is achieved by virtue of
the fact that in each
case a number of elevations which cross the respective portion are configured
in the portions of
the depressions parallel or substantially parallel to the extent of the
lamellar plates, which
elevations run in an at least substantially straight manner and have a base
width and a height of
from 0.2 mm to 0.3 mm, and the mutual spacing of which is between 1 mm and 1.5
mm, and the
course of which is interrupted by the ventilating bores.
The elevations act as spacer elements during the shaping of the green tire, as
a result of which
the enclosed air is divided into a multiplicity of part air quantities and
targeted discharge of the
part air quantities into the ventilating bores is assisted effectively.
Ventilating channels which
ensure geometrically exact shaping of the block and sipe edges as a result of
the optimized
discharge of the air into the ventilating bores are therefore formed between
the elevations.
In vulcanization molds which shape tread strips of winter tires, it is
customary to anchor lamellar
plates which are designed correspondingly for forming sipes which run in a
straight, zigzag or
undulating manner in plan view. In order to ensure satisfactory discharge of
the enclosed air into
the ventilating bores even in lamellar plates of this type, according to the
invention at least one
elevation is provided which, interrupted correspondingly by the lamellar
plate, crosses the zigzag
or undulating portions of the lamellar plate. Furthermore, lamellar plates are
also customary which
are configured for forming sipes which run in a stepped manner in plan view
and accordingly have
alternately short and longer portions. In lamellar plates of this type, it is
advantageous if at least
one elevation has a course which coincides with a longer portion of the
lamellar plate and the
course of said elevation is interrupted along said portion.
In order to ensure discharge of air which is as optimum as possible during
shaping of the green
tire in all those regions of the vulcanization mold which form profile
positives with sipes, the
elevations are configured in all regions of the depressions.
Furthermore, the invention relates to a pneumatic vehicle tire, in particular
a passenger car winter
tire, having a tread strip which has profile blocks and/or block-like profile
positives which, in a
vulcanization mold according to the invention, have been provided with sipes
by means of lamellar
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plates and with micro-grooves by means of elevations. The pneumatic vehicle
tire therefore has
micro-grooves which all run in a straight manner and parallel or substantially
parallel to the extent
of the sipes in the profile blocks and/or the block-like profile positives.
The micro-grooves which
are formed in the tread strip by way of a measure for improving the discharge
of air in the tire
vulcanisation mold are advantageous in a novel tire, since they assist the
grip on snow and ice.
It is therefore also advantageous for tire properties if the tread strip is
composed of profile blocks
and/or block-like profile positives which are provided in each case with a
number of sipes and
micro-grooves which run parallel or substantially parallel to said sipes.
Hence, according to a broad aspect, the invention provides a vulcanization
mold for vulcanizing
a pneumatic vehicle tire, the mold comprising mold segments which form a
profiled tread strip of
the tire and have mold webs which form depressions for forming profile blocks
or block-like profile
positives, lamellar plates for forming sipes in the profile blocks and/or
block-like profile positives
being anchored in depressions, the lamellar plates dividing the depressions
into portions, in which
in each case at least one ventilating bore is configured in the mold segment,
wherein in each case
a number of elevations which cross the respective depression are configured in
the portions of
the depressions parallel or substantially parallel to the extent of the
lamellar plates, which
elevations run in an at least substantially straight manner and have a base
width and a height of
from 0.2 mm to 0.3 mm, wherein a mutual spacing of which is between 1 mm and
1.5 mm, and
wherein a course of which is interrupted by the ventilating bores.
Brief description of the drawings
Further features, advantages and details of the invention will now be
discussed in more detail on
the basis of the drawing, which illustrates exemplary embodiments. In the
drawing:
fig. 1 diagrammatically shows a plan view of that part region of the inner
side of a vulcanization
mold for pneumatic vehicle tires which shapes a profile block,
fig. 2 shows a sectional illustration along the line II-II from fig. 1,
fig. 2a shows an enlarged illustration of a detail from fig. 2,
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fig. 3 shows a part section through a profile block, shaped in a vulcanization
mold according to
the invention, and
fig. 4 shows a partial developed view of a tread strip which has been
vulcanized in a vulcanization
mold which is configured according to the invention.
Detailed description of embodiments
Variants, examples and preferred embodiments of the invention are described
hereinbelow. A
vulcanization mold for passenger car tires is usually composed of side shells
which shape the
sidewalls of the tire and of from seven to thirteen mold segments which shape
the tread strip
region of the tire and are provided with the tread strip profiling.
Furthermore, a vulcanization mold
for passenger car tires contains on average approximately 4500 ventilating
bores which are
predominantly situated in the mold segments. The ventilating bores can be
simple bores or
ventilating units which contain ventilating valves can be inserted into the
bores. The ventilating
bores ensure discharge of that air to the outside which is present during the
shaping of the green
tire between the latter and the tire mold. In comparison with simple
ventilating bores, inserted
ventilating units have the advantage that they ensure the required ventilation
during shaping of
the green tire, but close the bores when the green tire has been molded.
Fig. 1 shows a view of that part region of a mold segment of a tire
vulcanization mold which
shapes a profile block of the tread strip, fig. 1 showing the rectangular
outline of said part region
which is delimited by mold webs which shape grooves. Accordingly, the small
region of the tire
vulcanization mold which is shown is a rectangular depression which is
delimited by mold webs
and shapes a profile block which is rectangular in plan view. The arrow U
denotes the
circumferential direction of the shaped tread strip. The depression 1 has two
bounding walls which
are oriented in the transverse direction and two bounding walls which are
oriented in the
circumferential direction U; fig. 2 shows the two walls la which run in the
transverse direction.
Lamellar plates 2 which run parallel to one another and to the walls la divide
the depression 1 in
the transverse direction and are spaced apart at least substantially uniformly
from the walls 1a of
the depression 1 which run in the transverse direction. For the sake of
simplicity, the lamellar
plates 2 are denoted as flat plates which are oriented in the radial
direction, have a thickness of
between 0.4 mm and 0.6 mm and accordingly shape sipes of said width which run
in a straight
manner in the profile block of the tire. The lamellar plates 2 divide the
depression 1 into portions
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3 of equal size, from the bottom of which in each case three ventilating bores
4 run into the mold
segment interior. Two of the ventilating bores 4 are arranged on the lateral
edge sections of the
portions 3, and one ventilating bore 4 is arranged in the middle region.
Elevations 5 are configured
on the mold inner side parallel to the lamellar plates 2 between the
individual lamellar plates 2
and the respectively outer lamellar plate 2 and the adjacent wall la of the
depression 1 which
runs in the transverse direction. In the embodiment which is shown, three
elevations 5 are
provided in each portion 3, which elevations 5 are likewise at at least
substantially the same
spacing from one another and from the lamellar plates 2. The elevations 5 are
of preferably
rectangular or square cross section, their width b is from 0.2 mm to 0.3 mm,
and their height h is
likewise from 0.2 mm to 0.3 mm. Their spacing a from one another and their
spacing a from the
wall la and from the lamellar plates 2 is between 1 mm and 1.5 mm.
The course of the elevations 5 is interrupted by way of the ventilating bores
4. The elevations 5
act as spacer elements during the molding process of the green tire into the
vulcanization mold.
The green tire comes into contact with the elevations 5 toward the end of the
molding process,
with the result that the air which is enclosed between the outer side of the
green tire and the inner
side of the depression 1 is divided into a multiplicity of part air quantities
which assist targeted
ventilation or discharge of the enclosed air into the ventilating bores 4.
Therefore, correct and
exact shaping of the profile block in the depression 1, in particular the
sipes, is ensured by way
of the lamellar plates 2, with the result that exactly shaped grip edges are
formed in the profile
block.
A vulcanization mold according to the invention has elevations 5 as spacer
elements at least in
those regions which form profile blocks which have a number of sipes. The
majority of the
elevations 5 have a connection to at least one ventilating bore 4. However,
elevations which do
not have a connection to a ventilating bore can also be provided sporadically,
above all in regions
which form corner regions of profile positives.
Fig. 4 shows a partial developed view of one design variant of a tread strip
of a passenger car
winter tire, which tread strip is heated in a vulcanization mold according to
the invention, B
denoting the width of that part of the tread strip which makes contact with
the ground, the width
which the tire assumes in the ground contact area when rolling, determined
according to the
ETRTO standards. M-M denotes the middle circumferential line of the tread
strip, the tire equator.
The tread strip profile which is shown by way of example is of asymmetric
design and therefore
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has profile positives of structurally different configuration in the two tread
strip halves. On the
shoulder side, the tread strip has in each case one block row 6, 8 which runs
around in the
circumferential direction and is composed in each case of blocks 6a and 8a
which are separated
from one another in the circumferential direction by way of transverse grooves
7, 9. A further block
row 11 with blocks 11a which are separated from one another by way of
transverse grooves 12
adjoins the block row 6, in a manner which is separated from the latter by way
of a circumferential
groove 10 which runs around in the circumferential direction. A further
circumferential groove 13
separates the block row 11 from a circumferential region which reaches as far
as the second
shoulder-side block row 8 and in which profile blocks 18 and block-like
profile positives 19, 20 are
formed. A further circumferential groove 14 runs to the block row 8. Starting
from the
circumferential groove 14, oblique grooves 15 run in a manner which is curved
arcuately at least
slightly at an angle a of from approximately 35 to 45 until beyond the
middle circumferential line
M-M. Further oblique grooves 16 and 17 which are oriented in the opposite
direction with respect
to the oblique grooves 15 divide said region of the tread strip into the
profile blocks 18 and the
block-like profile positives 19, 20.
All of the blocks 6a, 8a, 11a, 18 and all of the block-like profile positives
19, 20 are provided in
each case with a number of sipes 21, 22 which extend parallel to one another.
As viewed in plan
view, the sipes 21 in the blocks 8a, 18 and the block-like profile positives
19, 20 have a
substantially stepped course with alternately short and longer portions 21a,
21b and extend
parallel to transverse grooves 9 in the shoulder-side block rows 11 and with
respect to the oblique
grooves 15, 16 between the blocks 18 and the block-like profile positives 19,
20. The sipes 22 in
the shoulder-side blocks 6a and the blocks 11a have an undulating or zigzag
course with
approximately identically long portions in plan view. In the blocks 6a, the
sipes 22 extend parallel
to the transverse grooves 7 which run between the blocks 6a. The sipes 22
which are arranged
in the blocks 11a have a course which has the opposite angle with respect to
the transverse
grooves 12 between the blocks 11a.
All of the sipes 21 and 22 are formed by way of corresponding lamellar plates
and with a width of
from 0.4 mm to 0.6 mm. Furthermore, all of the blocks 6a, 8a, 11a, 18 and
block-like profile
positives 19, 20 are provided, in particular "covered", with a multiplicity of
micro-grooves 23, 23'
which run parallel to one another and have been formed by means of elevations
5 in the
vulcanization mold. The course of a majority of the micro-grooves 23, 23' is
interrupted by way of
round clearances 24 which have been formed at the locations of the ventilating
bores 4. The
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dimensions of the micro-grooves 23, 23, their width, their depth and their
spacing from one
another and their spacing from the block edges correspond to the
abovementioned dimensions
for b, h and a, as shown in fig. 3. In the blocks 6a, 11 a with sipes 22 which
run in an undulating
manner, the micro-grooves 23' run parallel to the extent of the sipes 22, with
two to three micro-
grooves 23' crossing the zigzag or undulating portions of the sipes 22. In the
blocks 8a, 18 and
the block-like profile positives 19, 20 with sipes 21 which run in a stepped
manner, the micro-
grooves 23 preferably run parallel to the longer portions 21b; some cross the
short portions 21a
of the sipes 21 ..
List of Designations
1 .............. Depression
la .............. Bounding wall
2 ............... Lamellar plate
3 ..... Portion
4 ............... Ventilating bore
5 ............... Elevation
6 ............... Block row
6a .............. Block
7 ..... Transverse groove
8 ............... Block row
8a .............. Block
9 ............... Transverse channel
10 .............. Circumferential groove
11 ... Block row
1 1 a ........... Block
12 .............. Transverse channels
13 .............. Circumferential groove
14 .............. Circumferential groove
15 .... Oblique groove
16 .............. Oblique groove
17 .............. Oblique groove
18 .............. Profile block
19 .............. Block-like profile positive
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20 .............. Block-like profile positive
21 ............. Sipe
21a ............ Portion
21b ............. Portion
22 ..... Sipe
23, 23' ........ Micro-grooves
24 .............. Clearances
................ Line
................ Width of the ground contact area
M-M ... Tire equator
a ............... Spacing
................ Width
................ Height
a ............... Angle
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