CA2929902C

CA2929902C - Vulcanization mold and pneumatic vehicle tire

Info

Publication number: CA2929902C
Application number: CA2929902A
Authority: CA
Inventors: Christian Brandau; Franz Diensthuber
Original assignee: Continental Reifen Deutschland GmbH
Current assignee: Continental Reifen Deutschland GmbH
Priority date: 2013-12-09
Filing date: 2014-10-07
Publication date: 2019-05-28
Anticipated expiration: 2034-10-07
Also published as: DE102013225298A1; CN105813819A; EP3079875A1; PL3079875T3; CA2929902A1; CN105813819B; WO2015086186A1; EP3079875B1

Abstract

The invention relates to a vulcanization mold for vulcanizing a pneumatic vehicle tire, in particular a winter passenger-car tire, comprising mold segments, which form the profiled tread of the tire and have molding ridges, which form recesses (1) for forming profile blocks (6a, 8a, 11a) or block-like profile positives (19, 20), wherein lamellar sheets (2) are anchored in recesses (1) in order to form incisions (21, 22) in the profile blocks (6a, 8a, 11a) or block-like profile positives (19, 20), wherein the lamellar sheets (2) divide the recesses (1) into sections (3), in each of which at least one venting bore (4) is formed in the mold segment. In each of the sections (3) of the recesses (1), a number of elevations (5) crossing the particular recess (1) parallel or substantially parallel to the extent of the lamellar sheets (2) is formed, the course of which elevations is interrupted at the venting bores (4). The invention further relates to a pneumatic vehicle tire that is produced by means of the vulcanization mold.

Description

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

2 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

3 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,

4 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

5 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

6 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 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

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

Claims

9

1. 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.

2. The vulcanization mold of claim 1, wherein the lamellar plates are configured for forming sipes which run in a straight, zigzag or undulating manner in plan view, at least one elevation, interrupted correspondingly by the lamellar plate, crossing the zigzag or undulating portions of the lamellar plate.

3. The vulcanization mold of claim 1, wherein the lamellar plates are configured for forming sipes which run in a stepped manner in plan view and have alternately short and longer portions, at least one elevation having a course which coincides with a longer portion and the course of said elevation being interrupted along said portion.

4. The vulcanization mold of any one of claims 1 to 3, wherein the elevations are configured in all regions of the depression.