JP2009220418A - Tire forming mold and tire manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire forming mold which can change hardness within a micro range such as defined by a groove edge part or a sipe edge part, and a tire manufacturing method. <P>SOLUTION: This tire forming mold is equipped with a tread mold part 1 for molding the tread face of a tire, a cone ring 24 for heating the tread mold part 1 from the back and an imbedded member 6 which is imbedded in the tread mold part 1 and has the end part 6a projecting from the molding face 1a of the tread mold part 1. In addition, the tread mold part 1 has an inside member 11 including the molding face 1a, and a back member 12 arranged on the back face side of the inside member 11. Further, the imbedded member 6 has a penetration part 6b which penetrates the back member 12, and is formed of a material with a different heat conductivity from the inside member 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tire mold and a tire manufacturing method for vulcanizing a tire.

  Normally, the tread surface of a pneumatic tire is provided with groove portions such as circumferential grooves and lateral grooves, and land portions such as blocks and ribs divided by the groove portions, depending on the required tire performance and use conditions. Various tread patterns are formed. In addition, in a studless tire useful as a winter tire, a cut called a sipe is formed in a land portion, and an edge effect by the sipe enhances running performance on an ice road surface having a low friction coefficient.

  The block 90 shown in FIG. 8 is an example of a land portion, and its periphery is surrounded by a groove portion 91. In this example, two sipes 92 are arranged in a straight line on the surface of the block 90. The groove edge portion GE serving as the edge of the groove portion 91 and the sipe edge portion SE serving as the edge of the sipe 92 are places where an edge effect is exerted due to the collapse of the block 90 or the like, and influences on the braking performance and uneven wear resistance performance of the tire. Is big.

  By the way, the following Patent Document 1 describes a tire in which the hardness of the groove edge portion is locally increased. Further, Patent Document 2 described below describes a tire in which the hardness of the sipe edge portion as well as the groove edge portion is locally increased. These tires are intended to enhance the edge effect by the groove edge portion and the sipe edge portion and improve the braking performance (ice braking performance) on the ice road surface.

  However, the tires described in the following Patent Documents 1 and 2 have a special tread structure mainly composed of foam rubber, and the manufacturing method thereof includes forming a non-foam rubber into a thin film on the surface of the tread rubber made of foam rubber. It is arranged and a tread pattern is formed thereon. In these tires, the groove edge part and the sipe edge part are merely formed of different blended rubbers, and there are problems in manufacturing and there are concerns about problems such as interface peeling.

  Except for the case of using such a different compound rubber, a tire in which the hardness of the groove edge portion or the sipe edge portion is locally different, and a tire mold and a tire manufacturing method capable of forming such a tire are described in the present invention. As far as the person knows, it does not exist by the time of this application.

  Patent Document 3 below discloses a tire molding die in which a heating unit or a cooling unit is provided in a mold part for molding a tread surface of a tire so that a rigidity difference is provided between a kicking side and a stepping side of a block. However, since this tire molding die is for heating or cooling the tread surface indirectly by a pipe line or a heater provided at a position away from the tread surface, a rigidity difference is easily generated only in the vicinity of the tread surface, The portion where the difference in rigidity is caused disappears early due to wear.

On the other hand, using the tire molding die described in Patent Document 3 below, when applying a rigidity difference between the kicking side and the stepping side of the block, heating with a pipe line or a heater is performed for a region having a certain extent. Cooling is also conceivable. However, in this case, although the portion causing the rigidity difference is formed deeply, the change in rigidity in a minute range such as the groove edge portion or the sipe edge portion cannot be obtained.
JP-A-8-175116 Japanese Patent Laid-Open No. 5-147412 JP 11-165320 A

  This invention is made | formed in view of the said situation, The objective is to provide the tire shaping | molding die and tire manufacturing method which can change hardness in a micro range, such as a groove edge part and a sipe edge part.

  The above object can be achieved by the present invention as described below. That is, the tire mold according to the present invention includes a tread mold part that molds a tread surface of a tire, a heating unit that heats the tread mold part from the back side, and a tread mold part embedded in the tread mold part. An embedding member having an end projecting from a molding surface, and the tread mold portion includes an inner member including the molding surface and a back member disposed on the back side of the inner member, The member has an intrusion portion that has invaded the back member, and is formed of a material having a thermal conductivity different from that of the inner member.

  In this tire mold, since the tread mold portion includes the inner member including the molding surface and the back member disposed on the back side thereof, the back member first becomes high temperature, and the heat of the tire passes through the inner member. It is transmitted to the tread surface. In addition, by providing the embedded member as described above, the heat of the back member is transmitted to the tread surface via the inner member, and the embedded member is utilized by utilizing the difference in heat conduction between the inner member and the embedded member. The temperature of the protruding end portion of can be made different from the temperature of the molding surface. For this reason, the hardness of the rubber around the protruding end of the embedded member can be locally changed, and the tire performance is improved by changing the hardness within a minute range such as the groove edge portion and the sipe edge portion. be able to.

  Further, according to the tire molding die of the present invention, it is possible to deeply form the portion where the hardness changes along the protruding end portion of the embedded member, and the improvement effect of the tire performance is improved until the end of wear. It can last. And since it is not necessary to form a groove edge part and a sipe edge part with different compounded rubber, a normal unvulcanized tire can be used and there is no fear that interface peeling will occur in a place where hardness differs.

  The tire manufacturing method according to the present invention includes a step of setting an unvulcanized tire in a tire mold and then heating the tire and pressing the molding surface of the tread mold portion against the tread surface to perform vulcanization molding. In the manufacturing method, the tread mold portion includes an inner member including the molding surface and a back member disposed on the back side of the inner member, and is embedded in the tread mold portion to end from the molding surface. When the embedded member from which the protrusion protrudes has a penetrating portion that has penetrated into the back member, and the tire is vulcanized and molded using a tire mold that is formed of a material having a thermal conductivity different from that of the inner member. Further, the difference between the heat conduction between the inner member and the embedded member is utilized while heating the tread mold part from the back side and transferring the heat of the back member to the tread surface through the inner member. , The temperature of the protruding ends of the serial embedded members and wherein varying the temperature of the molding surface.

  In this tire manufacturing method, when the tire is vulcanized, the protruding end of the embedded member is utilized by utilizing the difference in heat conduction between the inner member of the tread mold portion and the embedded member embedded in the tread mold portion. Since the temperature of the part can be made different from the temperature of the molding surface, the hardness of the rubber around the protruding end of the embedding member can be locally changed. The tire performance can be improved by changing the hardness within a certain range.

  Further, according to the tire manufacturing method of the present invention, it is possible to deeply form the portion where the hardness changes along the protruding end portion of the embedded member, and the improvement effect of the tire performance is improved until the end of wear. It can last. And since it is not necessary to form a groove edge part and a sipe edge part with different compounded rubber, a normal unvulcanized tire can be used and there is no fear that interface peeling will occur in a place where hardness differs.

  In the tire molding die and the tire manufacturing method according to the present invention, the protruding end portion of the embedded member constitutes a bone portion for forming a groove portion on the tread surface or a blade for forming a sipe on the land portion. can do.

  It is possible to locally change the hardness of the groove edge portion when the protruding end portion of the embedding member constitutes a bone portion, and the hardness of the sipe edge portion when it constitutes a blade. As a result, for example, by increasing the hardness of the groove edge part and sipe edge part locally to increase the rigidity, the edge effect due to the ridge line of the block and the sipe can be improved and the ice braking performance can be improved. Useful.

  Further, when traveling on a dry road surface, the contact pressure at the groove edge portion is higher than that at the central portion of the land portion, and as a result, the contact pressure tends to be uneven. Therefore, by lowering the rigidity locally by lowering the hardness of the groove edge part, the contact pressure at the groove edge part is lowered and the contact pressure at the land part is made uniform, and the braking performance and uneven wear resistance performance on the dry road surface are improved. It can be improved and is particularly useful as a summer tire.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view schematically showing an example of a tire mold according to the present invention, showing a clamped state. In FIG. 1, the tire (not shown) is set so that the tire axial direction is up and down, the right side in FIG. 1 is the inside in the tire radial direction, and the left side in FIG. 1 is the outside in the tire radial direction.

  The tire mold 20 (hereinafter sometimes simply referred to as “mold 20”) includes an annular tread mold portion 1 that molds a tread surface of a tire and a pair of sides that mold an outer surface of a sidewall portion of the tire. The mold parts 2 and 3 and a pair of bead rings 4 disposed on the inner side in the tire radial direction of the side mold parts 2 and 3 are provided. The tire set in the mold 20 is in a state where the bead portion is fixed by the bead ring 4.

  The molding surface 1a on the inner peripheral side of the tread mold portion 1 has a bone portion for forming a groove portion in the tread surface of the tire and a recess for forming a land portion divided by the bone portion. Is provided. A blade for forming a sipe on the land portion of the tread surface is disposed in the recess as necessary. At the time of vulcanization molding, the molding surface 1a is pressed against the tread surface of the unvulcanized tire, and a tread pattern corresponding to the bone portion and the recess is formed.

  The mold 20 of the present embodiment is a so-called segmented mold, and the tread mold portion 1 is composed of a combination of sectors divided in the tire circumferential direction. That is, the tread mold portion 1 is in a state in which the sectors are gathered together to form a continuous annular shape when the mold is clamped, and is in a state of being separated from each other by being displaced outward in the tire radial direction when the mold is opened.

  The tread mold portion 1 includes an inner member 11 including a molding surface 1 a and a back member 12 disposed on the back side of the inner member 11. The inner member 11 may be integrally formed as shown in FIG. 2A, but may be constituted by a combination of a plurality of pieces as shown in FIG. The inner member 11 is fitted on the inner peripheral side of the back member 12 and is fixed so as not to drop off by a bolt, a stopper, or the like. In addition, in FIG. 2, description about the uneven | corrugated shape (bone part and a recess) of the molding surface 1a is abbreviate | omitted.

  An example of the material of the inner member 11 is aluminum. This aluminum is a concept that includes not only pure aluminum materials but also aluminum alloys. For example, Al-Cu, Al-Mg, Al-Mg-Si, Al-Zn-Mg, Al-Mn System and Al-Si system. On the other hand, as the material of the back member 12, a material different from the inner member 11 is preferably adopted, and an iron-based material such as steel is exemplified.

  The tread mold 1 is surrounded by a cone ring 24 as a heating means. The cone ring 24 is provided with a passage 26 so that the heating fluid flows through the passage 26. Examples of the heating fluid include steam, gas, and hot water. By the flow of the heating fluid, the tread mold portion 1 is heated to a predetermined temperature from the back side.

  Although not shown, a lower platen is disposed below the side mold part 2, and an upper platen is disposed above the side mold part 3. Each of these platens has a passage formed therein, and is configured so that the heated fluid flows in the same manner as the cone ring 24. The side mold parts 2 and 3 are heated to a predetermined temperature by the flow of the heating fluid.

  A container 21 is attached to each outer peripheral surface on the back side of the tread mold 1 for each sector. The container 21 is slidably attached along the tire radial direction to the lower surface of a side plate 23 configured to be movable up and down. The cone ring 24 is fitted to a rail 25 provided on the outer slope of the container 21, and is configured to be movable up and down relatively with respect to the side plate 23.

  In the mold clamping state shown in FIG. 1, when the cone ring 24 is raised and the container 21 is moved outward in the tire radial direction, the tread mold part 1 expands and is separated from the side mold parts 2 and 3, and further the side When the plate 23 and the container 21 are raised, the tread mold part 1 and the side mold part 3 are lifted to shift to the mold open state. The transition from the mold opening state to the mold clamping state may be performed by reversing the above operation.

  Although not shown, a rubber bag called a bladder is installed inside the mold 20. At the time of vulcanization molding, the tread surface of the tire is pressed against the molding surface 1a by expanding the bladder outward in the tire radial direction. It is also possible to use a rigid core instead of the bladder.

  As shown in FIG. 1, the molding die 20 includes an embedding member 6 embedded in the tread mold portion 1 and having an end portion 6 a protruding from the molding surface 1 a of the tread mold portion 1. The end portion 6a is a portion that presses against the tread surface of the tire to form a recess. Therefore, the protruding end portion 6a of the embedded member 6 can constitute a bone portion for forming a groove portion on the tread surface or a blade for forming a sipe on the land portion of the tread surface.

  The embedded member 6 has an intrusion portion 6 b that enters the back member 12. In the present embodiment, the end opposite to the end 6a of the embedded member 6 enters the back member 12, and this end becomes the intrusion 6b. The embedded member 6 is made of a material having a thermal conductivity different from that of the inner member 11. For this reason, although heat is supplied from the back member 12 heated by the cone ring 24 to the inner member 11 and the embedded member 6, the heat is easily transmitted differently.

  FIG. 3 is an essential part enlarged view conceptually showing a cross section of the tread mold part 1. In this figure, one bone portion 61 and one blade 62 are representatively shown, but a plurality of bone portions and a plurality of blades are arranged in a complex manner on the actual molding surface 1a.

  As shown in FIG. 3, each of the bone portion 61 and the blade 62 is constituted by the protruding end portion 6 a of the embedded member 6. That is, the embedded members 6 </ b> A and 6 </ b> B embedded in the tread mold 1 have their end portions protruding from the molding surface 1 a, and the protruding end portions serve as the bone portion 61 and the blade 62. Further, the embedded members 6A and 6B have end portions 63 and 64 opposite to the end portions constituting the bone portion 61 or the blade 62 inserted into the back member 12, and these constitute the intrusion portion 6b.

  FIG. 4 is an enlarged view of a main part conceptually showing a cross section of a tread mold part included in a conventional mold. As shown in FIG. 4, in the tread mold part 95 provided in the conventional mold, the bone part 96 is provided integrally with the molding surface 98, or the blade 97 is embedded in the molding surface 98 at a depth of about several millimeters. Have been. Therefore, by heating the tread mold portion 95 to a predetermined temperature, the temperatures of the bone portion 96, the blade 97, and the molding surface 98 become equal.

  In the present invention, the material of the embedded member 6 is not particularly limited as long as it has a thermal conductivity different from that of the inner member 11. Whether to set the thermal conductivity of the embedded member 6 higher or lower than that of the inner member 11 may be appropriately selected according to the tire performance to be improved, and will be described in detail later. In addition, it is preferable to interpose a heat insulating material between the embedded member 6 and the inner member 11 to suppress heat transfer between them.

  In the present embodiment, an example is shown in which the inner member 11 is formed of aluminum, the back member 12 is formed of steel, and the embedded member 6 is formed of a material (for example, SUS) having a lower thermal conductivity than the inner member 11. For reference, it is known that the thermal conductivity near room temperature is 236 for aluminum, 84 for iron, and 390 for copper (unit: W / (m · K)).

  In the tire molding die of the present invention, the shape and moving mechanism of the tread mold part and the side mold part, the bone part and the recess, the shape of the blade, the presence / absence of the blade, and the like can be appropriately changed according to the use and conditions. It is. The present invention can also be applied to a so-called two-piece mold in which the tread mold portion is divided in the tire width direction.

  Hereinafter, a method for manufacturing a tire using the above mold will be described. First, an unvulcanized tire is set in the mold 20 and clamped. Next, the bladder is inflated so that the tread surface of the tire is pressed against the molding surface 1 a and the outer surface of the sidewall portion of the tire is pressed against the inner peripheral surfaces of the side mold portions 2 and 3. At this time, a groove portion is formed on the tread surface by the bone portion 61, and a sipe is formed on the tread surface by the blade 62.

  The tread mold part 1 and the side mold parts 2 and 3 are heated to a predetermined temperature by the cone ring 24 and the platen, respectively, and the unvulcanized tire in the mold 20 has an appropriate vulcanization temperature (for example, 160 to 180 ° C.). Degree). More specifically, the cone ring 24 heats the tread mold part 1 from the back side, so that the back member 12 first becomes high temperature, and the heat is transmitted to the tread surface of the tire via the inner member 11. , Mainly used for vulcanization of tread rubber.

  At this time, while the heat of the back member 12 is transmitted to the tread surface via the inner member 11, the projecting end portion of the embedded member 6 is utilized by utilizing the difference in thermal conduction between the inner member 11 and the embedded member 6. The temperature of 6a is made different from the temperature of the molding surface 1a. In this embodiment, since the thermal conductivity of the embedded member 6 is lower than that of the inner member 11 and heat from the back member 12 is less likely to be transmitted as compared to the inner member 11, the temperature of the end portion 6a is set higher than the temperature of the molding surface 1a. Can also be lowered.

  Therefore, if the end 6a of the embedded member 6 constitutes the bone 61, the bone 61 pressed against the tread surface Tr forms the groove 81 as shown in FIG. The temperature of the area A around 61 can be made lower than the other parts, and the hardness of the rubber in the area A can be increased. As a result, the hardness of the groove edge portion GE serving as the edge of the groove portion 81 can be locally increased.

  If the end 6a of the embedded member 6 constitutes the blade 62, as shown in FIG. 6, when the blade 62 pressed against the tread surface Tr forms a sipe 82, Thus, the temperature of the region B can be made lower than that of the other parts, and the hardness of the rubber in the region B can be increased. As a result, the hardness of the sipe edge portion SE that becomes the edge of the sipe 82 can be locally increased.

  Thus, by increasing the hardness of the groove edge portion GE and the sipe edge portion SE locally to increase the rigidity, the edge effect due to the ridge line of the block and the sipe can be enhanced, and the ice braking performance can be improved. In addition, since the hard part of the rubber can be formed deeply along the depth direction of the groove 81 or sipe 82 as in the areas A and B, the groove edge part GE and the sipe edge part SE always have hardness even if wear progresses. Therefore, the effect of improving the tire performance can be favorably maintained until the end of wear.

  In the present invention, all the bones and blades in the molding surface 1a can be constituted by the end 6a of the embedding member 6. However, the present invention may be applied only to some bones or blades in the molding surface 1a. Absent. Therefore, for example, only the embedded member related to the bone portion forming the transverse groove may be cooled, and in that case, the hardness is intensively increased especially in the groove edge portion which has a large contribution to the braking performance. It is done. In addition, in the present invention, various variations are conceivable with respect to the arrangement of the places where the hardness is changed, such as changing the hardness of the sipe edge portion every other when a plurality of sipes are arranged in parallel.

  By the way, in the present invention, the embedded member 6 is formed of a material having a higher thermal conductivity than the inner member 11 (for example, a copper-based material), and heat from the back member 12 is more easily transmitted than the inner member 11, It is possible to raise the temperature of the part 6a higher than the temperature of the molding surface 1a. In this case, contrary to the above, the rigidity of the rubber around the end portion 6a can be lowered to reduce the rigidity. As a result, for example, it is possible to reduce the rigidity of the groove edge portion GE, which tends to increase the contact pressure on the dry road surface, thereby making the contact pressure on the land portion uniform, and improving the braking performance and uneven wear resistance performance on the dry road surface. it can.

  From the viewpoint of appropriately exerting the tire performance improvement effect such as the improvement of the ice braking performance and the dry braking performance, it is preferable to cause a hardness difference of 4 ° or more between the rubber around the end portion 6a and the rubber in the other portion. This rubber hardness is a value measured according to the JISK6253 durometer hardness test (type A).

  When describing such a rubber hardness difference, it is assumed that the rubber hardness around the end portion 6a is measured in the hatched region in FIG. 7, and the rubber hardness of the other portion is measured outside the region. . That is, the hardness of the groove edge portion GE is measured within a range of 10% of the land lengths X and Y from the ridge line of the block, and the hardness of the sipe edge portion SE is such that the distance d from the sipe 82 is about 1 mm. It shall be measured within the range.

  In the above description, it has been described that the hardness of the peripheral rubber is increased by lowering the temperature of the end portion 6a, and the hardness of the peripheral rubber is decreased by increasing the temperature of the end portion 6a. It can be explained from the relationship with behavior. In other words, in rubber vulcanization, the higher the vulcanization temperature, the earlier the start time of vulcanization reversion. Therefore, the higher the vulcanization temperature, the more rubber the vulcanization time used for general tire vulcanization molding. The hardness tends to be low.

  Therefore, depending on conditions such as the vulcanization time and rubber compounding, such as when the vulcanization time is short enough that reversion does not occur, contrary to the above, if the temperature at the end of the embedded member is lowered, There is a possibility that the hardness of the rubber will decrease. However, this is not a problem in the present invention. This is because it can be easily grasped in advance which phenomenon will occur under the vulcanization conditions to be carried out, depending on whether the hardness is increased or decreased around the end of the embedded member. This is because it is only necessary to select whether the thermal conductivity is higher or lower than that of the inner member.

  In the tire manufacturing method according to the present invention, when the tire is vulcanized and molded, the temperature of the protruding end portion of the embedded member is formed by utilizing the difference in heat conduction between the inner member and the embedded member as described above. Except for making it different from the temperature of the surface, it is the same as the normal tire manufacturing method, and conventionally known manufacturing methods and steps can be applied except for the steps related to vulcanization molding.

  Examples that specifically show the structure and effects of the present invention will be described below. Each performance evaluation of the tire was performed as follows.

(1) Ice braking performance The tire is mounted on a 2500cc class passenger car (rear wheel drive), runs on the ice platen road surface (friction coefficient μ ≒ 0.1), and the braking force is applied at a speed of 40km / h to operate the ABS. The braking distance was evaluated with an index. The result of Comparative Example 1 is set to 100, and the larger the value, the shorter the braking distance and the better the ice braking performance.

(2) Dry braking performance The tire is mounted on a 2500cc class passenger car (rear wheel drive), driven on a dry road surface (friction coefficient μ ≒ 1.0), and braking force is applied at a speed of 100km / h to operate the ABS. The braking distance was evaluated with an index. The result of Comparative Example 2 is set to 100, and the larger the value, the shorter the braking distance and the better the dry braking performance.

  Two types of unvulcanized tires with different tread rubber formulations were prepared. One is a rubber compounding (A compounding) used for a general studless tire (winter tire), and the other is a rubber compounding (B compounding) used for a general summer tire (summer tire). . Table 1 shows the relationship between the vulcanization temperature and the rubber hardness when the vulcanization time is 10 minutes for the rubbers of A and B.

  The measured value in Table 1 refers to the value measured according to the hardness test described above. The same applies to the rubber hardness in Table 2 below. From Table 1, it can be seen that the rubbers of these A blends and B blends have lower hardness as the vulcanization temperature is higher during vulcanization for 10 minutes. Therefore, in this case, if it is desired to increase the rubber hardness, the vulcanization temperature may be set low.

Comparative Example 1
Comparative Example 1 was obtained by vulcanizing and molding an unvulcanized tire having a tire size of 215 / 60R16 and a tread rubber compounding of compounding A by a usual method. The vulcanization temperature was 180 ° C., the vulcanization time was 10 minutes, and the sipe distance (blade distance) was 4 mm. In Comparative Example 1, the tread mold portion is pressed against the tread surface of the unvulcanized tire in a state where the molding surface of the tread portion, the bone portion, and the blade are heated and held at the same temperature.

Example 1
In vulcanization molding of an unvulcanized tire, Example 1 was made the same as Comparative Example 1 except that the tire molding die as described above was used. In this mold, the material of the inner member is aluminum, and the material of the back member and the embedded member is SUS. In Example 1, the temperature of the molding surface of the tread mold part is different from the temperature of the end part of the embedded member, and the hardness of the rubber around the bone part and the sipe is locally changed.

Comparative Example 2
Comparative Example 2 was the same as Comparative Example 1 except that the tread rubber was mixed with B and the vulcanization temperature was 160 ° C. In Comparative Example 2, no blade is provided in the mold.

Example 2
Example 2 was the same as Comparative Example 2 except that a tire mold as described above was used for vulcanization molding of an unvulcanized tire. In this mold, the inner member is made of aluminum, the back member is made of SUS, and the embedded member is made of copper. In Example 2, the temperature of the molding surface of the tread mold part is different from the temperature of the end part of the embedding member, and the hardness of the rubber around the bone part is locally changed.

  Table 2 shows the results of examining the hardness of the tread rubber, the hardness of the edge portion, and the braking performance of Comparative Examples 1 and 2 and Examples 1 and 2. In Table 2, “the hardness of the edge portion” is the rubber hardness measured at the sipe edge portion in Comparative Example 1 and Example 1, and the rubber hardness measured at the groove edge portion in Comparative Example 2 and Example 2. is there.

  From Table 2, it can be seen that in Comparative Example 1, the hardness of the tread rubber is uniformly 45 °, whereas in Example 1, the hardness changes locally at the sipe edge portion. As a result, in Example 1, the edge effect is enhanced and the ice braking performance can be improved. In Comparative Example 2, it can be seen that the hardness of the tread rubber is uniformly 54 °, whereas in Example 2, the hardness changes locally at the groove edge portion. As a result, in the second embodiment, the ground contact pressure in the block is made uniform to improve the dry braking performance.

1 is a longitudinal sectional view schematically showing an example of a tire mold according to the present invention. The perspective view which shows roughly one of the sectors which comprise a tread type | mold part The principal part enlarged view which showed notionally the cross section of the tread type | mold part with which the tire shaping | molding die of this embodiment is equipped The principal part enlarged view which showed notionally the cross section of the tread type | mold part with which the conventional tire shaping | molding die is equipped Cross-sectional view showing the surroundings of the bone during vulcanization molding Sectional view showing the surroundings of the blade during vulcanization molding Plan view of block to show rubber hardness measurement area Perspective view of block with sipes formed

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread type | mold part 1a Molding surface 6 Embedded member 6a End part 6b which the embedded member protruded Intrusion part 11 Inner member 12 Back member 20 Tire shaping | molding die 24 Cone ring (heating means)
26 Passage 61 Bone 62 Blade 81 Groove 82 Sipe GE Groove Edge SE SEipe Edge

Claims (4)

A tread mold part that molds the tread surface of the tire, a heating means that heats the tread mold part from the back side, and an embedded member that is embedded in the tread mold part and protrudes from the molding surface of the tread mold part And
The tread mold portion includes an inner member including the molding surface and a back member disposed on the back side of the inner member, and the embedded member includes an intrusion portion that has penetrated the back member, A tire molding die formed of a material having a thermal conductivity different from that of the inner member.   The tire molding die according to claim 1, wherein the projecting end portion of the embedded member constitutes a bone portion for forming a groove portion on a tread surface or a blade for forming a sipe on a land portion. In a tire manufacturing method including a step of vulcanizing and molding an unvulcanized tire in a tire mold and then heating the tire and pressing a molding surface of a tread mold portion on the tread surface,
The tread mold portion includes an inner member including the molding surface and a back member disposed on the back side of the inner member, and is embedded in the tread mold portion and having an end protruding from the molding surface. Using the tire mold that is formed of a material having a heat conductivity different from that of the inner member, while the intruding member has an intrusion portion that has invaded the back member,
When the tire is vulcanized and molded, the tread mold part is heated from the back side to transfer the heat of the back member to the tread surface through the inner member, and the heat of the inner member and the embedded member. A tire manufacturing method, wherein the temperature of the protruding end portion of the embedded member is made different from the temperature of the molding surface by utilizing a difference in conduction.   The tire manufacturing method according to claim 3, wherein the protruding end portion of the embedded member constitutes a bone portion for forming a groove portion on a tread surface or a blade for forming a sipe on a land portion.

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