Tire vulcanization mold and method for manufacturing pneumatic tires

Abstract

To provide a temperature sensor with excellent responsiveness to changes in a temperature of an object to be measured, a tire curing mold with such a temperature sensor, and a pneumatic tire production method using such a temperature sensor.SOLUTION: There is provided a temperature sensor 8 that comprises a resistive element 82 and a protective tube 81 that protects the resistance element 82. The protective tube 81 comprises: a first portion 811 that is located on a tip side of the protective tube 81 and made of a first material; and a second portion 812 that is located closer to the other end of the protective tube 81 than the first portion 811 and made of a second material. A thermal conductivity of the first material is greater than a thermal conductivity of the second material. According to such a configuration, heat conduction from an object to be measured (for example, a tread 3 of a tire being heat-vulcanized) to the resistance element 82 is excellent, and therefore a responsiveness of the temperature sensor 8 to changes in a temperature of the object to be measured is excellent. As a result, an end point of vulcanization can be obtained with high accuracy.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a temperature sensor, a tire vulcanizing mold, and a method for manufacturing a pneumatic tire. [Background technology]

[0002] In pneumatic tire production, seasonal factors can cause variations in the temperature of raw unvulcanized tires (i.e., raw tires), the temperature inside the mold, the ambient temperature, etc., so it is common to set a margin of time that takes these variations into account and incorporate this margin of time into the heating and vulcanization time. This is because if vulcanization is insufficient, air generated by the vulcanization reaction will remain in the vulcanized rubber, which could lead to damage to the pneumatic tire.

[0003] The leeway time can be eliminated or reduced by measuring the temperature during heating and vulcanization for each tire and then determining the end point of vulcanization for each tire. It is known to use a temperature sensor to measure the temperature change of the tire (i.e., the temperature change of the rubber) during heating and vulcanization (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-85524 Summary of the Invention [Problem to be solved by the invention]

[0005] It is desirable for the temperature sensor to have high responsiveness to temperature changes in the tire during heat vulcanization, because the higher the responsiveness of the temperature sensor, the more accurately the end point of vulcanization can be determined, thereby eliminating or reducing excessive heating.

[0006] An object of the present invention is to provide a temperature sensor that is highly responsive to temperature changes of an object to be measured. Another object of the present invention is to provide a tire curing mold equipped with such a temperature sensor, and to provide a method for manufacturing a pneumatic tire using such a temperature sensor. [Means for solving the problem]

[0007] In order to solve this problem, the temperature sensor of the present invention has the following configuration.

[0008] A temperature sensor for measuring a rubber temperature, A resistive element; a protective tube for protecting the resistance element, the protective tube comprises a first portion made of a first material and located on a tip side of the protective tube, and a second portion made of a second material and located on the other end side of the protective tube relative to the first portion, The thermal conductivity of the first material is greater than the thermal conductivity of the second material. Temperature sensor. Here, the "tip" of the protective tube means the end of the protective tube that is closest to the resistance element, and the "other end" means the other end of the protective tube. Furthermore, the first portion being "located on the tip side of the protective tube" implies that the first portion is located at least at the tip of the protective tube.

[0009] The temperature sensor of the present invention includes a resistance element, that is, the temperature sensor is a resistance thermometer, and therefore can detect temperature changes of the measurement object with higher accuracy than a thermocouple.

[0010] Furthermore, since the thermal conductivity of the first material constituting the first portion of the protective tube of the temperature sensor located at the tip end is greater than the thermal conductivity of the second material constituting the second portion located at the other end, the thermal conduction from the measurement object to the resistance element is superior compared to when the protective tube is made of only the second material, and the responsiveness of the temperature sensor to temperature changes of the measurement object is superior. As a result, for example, when the measurement object is rubber being heated and vulcanized, the end point of vulcanization can be determined with high accuracy.

[0011] It is preferable that the difference between the thermal conductivity of the first material and the thermal conductivity of the second material is 60 W / mK or more. If this difference is 60 W / mK or more, the thermal conductivity from the object to be measured to the resistance element is improved, and the responsiveness of the temperature sensor to temperature changes in the object to be measured is improved, which results in, for example, more accurate determination of the end point of vulcanization.

[0012] The tire vulcanizing mold of the present invention comprises: A tread mold for molding the tread of an unvulcanized tire is provided, The tread mold includes a plurality of segments divided in the tire circumferential direction, At least one of the segments includes a protrusion for forming a groove in the tread of the green tire, and the temperature sensor has at least the portion protruding from the protrusion.

[0013] The tire vulcanization mold of the present invention has at least one segment equipped with a temperature sensor, allowing for measurement of tire temperature changes with excellent responsiveness. Moreover, because at least the first portion protrudes from the protrusion for forming a groove in the tread, it is possible to embed the first portion in the tread of an unvulcanized tire, and the tire temperature can be measured with the first portion embedded in the tread of the tire being heated and vulcanized. As a result, the end point of vulcanization can be determined with high accuracy.

[0014] Preferably, at least a part of the second portion of the temperature sensor also protrudes from the protrusion. By having not only the first portion of the temperature sensor but also at least a part of the second portion protruding from the protrusion, heat conduction from the protrusion to the resistance element can be reduced compared to when only the first portion protrudes from the protrusion, so that the temperature change of the tire during heat vulcanization can be measured with high accuracy, and as a result, the end point of vulcanization can be determined with high accuracy.

[0015] It is preferable that the length of the portion of the protective tube that protrudes from the projection is 20% to 60% of the length of the portion that protrudes from the projection. By making the length of the first portion 20% or more, the heat conduction from the object to be measured to the resistance element is improved, and the responsiveness of the temperature sensor to the temperature change of the object to be measured is improved, so that the end point of vulcanization can be determined more accurately. On the other hand, by making the length of the first portion 60% or less, the heat conduction from the protrusion of the segment to the resistance element can be further reduced, so that the temperature change of the tire during heat vulcanization can be measured more accurately, and as a result, the end point of vulcanization can be determined more accurately.

[0016] The method for producing a pneumatic tire of the present invention includes a step of heating and vulcanizing an unvulcanized tire in the tire vulcanization mold.

[0017] According to the method for manufacturing a pneumatic tire of the present invention, the temperature change of the tire during heat vulcanization can be measured with excellent responsiveness, and as a result, the end point of vulcanization can be determined with high accuracy. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view of a main part of an unvulcanized tire in a tire meridian plane, which is heat-vulcanized in this embodiment. FIG. [Figure 2] FIG. 2 is a cross-sectional view conceptually showing a main part of the mold of the present embodiment. [Figure 3]1 is a cross-sectional view of a main portion near a temperature sensor when an unvulcanized tire is heated and vulcanized in a mold according to the present embodiment. This cross section is a cross section taken along a plane passing through the axis of the temperature sensor in the tire meridian plane. [Figure 4] 1 is a cross-sectional view of a main part near a temperature sensor when an unvulcanized tire is heated and vulcanized in a mold according to a modified example of the present embodiment. This cross section is a cross section taken along a plane passing through the axis of the temperature sensor in the tire meridian plane. [Figure 5] 1 is a cross-sectional view of a main part near a temperature sensor when an unvulcanized tire is heated and vulcanized in a mold according to another modification of the present embodiment, the cross section being taken along a plane passing through the axis of the temperature sensor in the tire meridian plane. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described.

[0020] It should be noted that in this specification, all concepts such as "first" and "second" are used solely for the purpose of distinguishing one thing from another, and do not indicate or suggest a relative order or technique.

[0021] In this specification, the tire width direction is the direction parallel to the tire rotation axis, which is the center of rotation of a pneumatic tire or an unvulcanized tire. The tire radial direction is the diameter direction of a pneumatic tire or an unvulcanized tire. The tire circumferential direction is the direction around the tire rotation axis. The tire equatorial plane is a plane that is perpendicular to the tire rotation axis and is located at the center in the tire width direction. The tire meridian plane is a plane that includes the tire rotation axis and is perpendicular to the tire equatorial plane.

[0022] Since the temperature sensor of this embodiment can be suitably used in the manufacture of pneumatic tires, we will first explain the unvulcanized tire that is the basis for pneumatic tires, and then explain the tire vulcanization mold and the method for manufacturing pneumatic tires.

[0023] <1. Unvulcanized tires> 1, an unvulcanized tire (hereinafter sometimes referred to as a "green tire") 9 includes a pair of bead portions 1, sidewalls 2 extending radially outward from each of the bead portions 1, and a tread 3 continuing to the radially outer ends of each of the sidewalls 2. Each bead portion 1 includes a bead core 1a extending circumferentially around the tire.

[0024] The carcass 4 extends from the tread 3 through the sidewalls 2 to the bead portions 1, with its ends folded back via the bead cores 1a. The carcass 4 is made up of at least one carcass ply. The carcass ply has carcass cords covered with topping rubber and extending at an angle of approximately 90° relative to the tire circumferential direction.

[0025] The belt layer 5 is bonded to the outside of the carcass 4 by the tread 3, and is covered from the outside with tread rubber 6. The belt layer 5 is composed of a plurality of belt plies, for example, two belt plies. Each belt ply has belt cords covered with topping rubber and extending at an angle to the tire circumferential direction. The belt plies can be layered so that the belt cords cross each other in opposite directions.

[0026] The tread 3 has a tread surface. The tread rubber 6 may be configured with only one layer, or may be configured with a so-called cap base structure having a base tread on the inner side in the tire radial direction and a cap tread located on the outer peripheral side thereof.

[0027] <2. Tire curing mold> As shown in FIG. 2, a tire curing mold (hereinafter sometimes referred to as the "mold") 10 includes a cylindrical tread mold 11 and a pair of upper and lower annular side molds 12 and 13 arranged radially inside the tread mold 11. Thus, the mold 10 includes the tread mold 11 capable of contacting the tread surface of a green tire 9, the side mold 12 (hereinafter sometimes referred to as the "lower mold 12") capable of contacting the tire's outer surface facing downward, and the side mold 13 (hereinafter sometimes referred to as the "upper mold 13") capable of contacting the tire's outer surface facing upward. These molds are configured to be freely displaceable between a mold-closed state and a mold-open state by an opening / closing mechanism (not shown) arranged around them. The green tire 9 is set in a cavity defined by the tread mold 11, the lower mold 12, and the upper mold 13. The tread mold 11 is divided circumferentially into a plurality of segments (see FIG. 3; specifically, segments 111). Each segment is movable in the radial direction of the green tire 9 placed in the mold 10. The mold 10 is provided with a platen (not shown) having a heat source such as an electric heater or a steam jacket, which heats each mold portion.

[0028] A central mechanism 14 is provided in the center of the mold 10 coaxially with the tire, and a tread mold 11, a lower mold 12, and an upper mold 13 are arranged around this. The central mechanism 14 has a rubber bag-shaped bladder 15 and a center post 16 extending in the tire width direction, and an upper clamp 17 and a lower clamp 18 that grip the ends of the bladder 15 are provided on the center post 16.

[0029] A medium supply path 21 for supplying a heating medium into the bladder 15 extends vertically in the central mechanism 14, and an outlet 22 is formed at the upper end of the medium supply path 21. A supply pipe 24 is connected to the medium supply path 21, through which the heating medium supplied from a heating medium supply source 23 and the pressurized medium supplied from a pressurized medium supply source 26 flow. The heating medium is supplied in response to the opening and closing operation of a valve 25, and the pressurized medium is supplied in response to the opening and closing operation of a valve 28.

[0030] Furthermore, a medium discharge path 31 extends vertically in the central mechanism 14 for discharging the high-temperature, high-pressure fluid, which is a mixture of the heating medium and the pressurizing medium in the bladder 15, and a recovery port 32 is formed at the upper end of the medium discharge path 31. A discharge pipe 34, through which the high-temperature, high-pressure fluid flows, is connected to the medium discharge path 31, and a blow valve 33 for opening and closing the discharge pipe 34 is provided on the discharge pipe 34. The high-temperature, high-pressure fluid may be forced to circulate by a pump 35 so that the high-temperature, high-pressure fluid passing through the medium discharge path 31 is resupplied into the bladder 15 via the medium supply path 21.

[0031] As described above, the mold 10 includes a tread mold 11 for molding the tread 3 (see FIG. 1) of the green tire 9, and the tread mold 11 includes a plurality of segments (see FIG. 3; specifically, segments 111) divided in the tire circumferential direction. Each segment includes a protrusion (see FIG. 3; specifically, protrusion 115) for forming a groove in the tread 3 of the green tire 9. The number of protrusions per segment may be one or more. For example, the number of protrusions per segment may be two, three, or four. The protrusions may extend in the tire circumferential direction. The protrusions are preferably protrusions for forming wide grooves, such as main grooves.

[0032] As shown in FIG. 3 , at least one of the segments 111 includes a temperature sensor 8 arranged to extend in the height direction of the protrusion 115. That is, at least one of the segments 111 includes a temperature sensor 8 arranged to extend in the tire radial direction. Here, the axis of the temperature sensor 8, i.e., the length direction of the temperature sensor 8, may or may not coincide with the tire radial direction. The length direction of the temperature sensor 8 can also be rephrased as the length direction of the protective tube 81. Considering the ease of inserting the temperature sensor 8 into the tread 3, it is preferable that the axis of the temperature sensor 8 coincide with the tire radial direction. The temperature sensor 8 can be fixed by any method.

[0033] The temperature sensor 8 includes a resistive element 82, a protective tube 81, and an internal conductor 83. The temperature sensor 8 may further include a terminal (not shown). The terminal may be formed from the end of the internal conductor 83. The protective tube 81 protects the resistive element 82 and the internal conductor 83 from the object to be measured and the atmosphere. The internal conductor 83 connects the resistive element 82 to the terminal. In the temperature sensor 8, the resistance value of the resistive element 82 changes with temperature, and therefore the temperature of the object to be measured can be derived by passing a measurement current through the resistive element 82 and then measuring the voltage across the resistive element 82.

[0034] Since the temperature sensor 8 includes the resistance element 82, it is possible to detect the temperature change of the tread 3, which is the measurement target, with higher accuracy than with a thermocouple.

[0035] Resistance element 82 is protected by a protective tube 81. Specifically, resistance element 82 is housed in protective tube 81, and is thereby protected from the object to be measured and the atmosphere.

[0036] Resistance element 82 is housed at the tip of protective tube 81. Specifically, resistance element 82 is housed in protective tube 81 so as to be surrounded by the inner surface of first portion 811 of protective tube 81.

[0037] The resistor element 82 may be a wire-wound resistor element or a thin-film resistor element, with a thin-film resistor element being preferred.

[0038] The number of resistive elements 82, that is, the number of elements, may be, for example, one, two, or three. Note that the number of elements may be three or more.

[0039] The protective tube 81 has a tubular shape with a closed tip. The tip may be rounded or not. The protective tube 81 may be coated with some kind of coating.

[0040] Protective tube 81 includes a first portion 811 located on the tip side of protective tube 81, and a second portion 812 located closer to the other end of protective tube 81 than first portion 811. First portion 811 and second portion 812 may be joined by welding, for example, or one may have a male thread and the other a female thread, with the two fitting together.

[0041] The first part 811 is located at least at the tip of the protective tube 81 and is adjacent to the second part 812. In this way, the first part 811 closes the opening of the second part 812 at the tip of the protective tube 81.

[0042] The first part 811 has a hole in which the resistance element 82 is housed. This hole opens toward the other end of the protective tube 81. This hole is connected to the cavity of the tubular second part 812 (i.e., the cavity surrounded by the inner surface of the second part 812).

[0043] The rearmost end of the first portion 811 may be located at the same position as the rearmost end of the resistance element 82 in the longitudinal direction of the temperature sensor 8, or may be located closer to the tip of the protective tube 81 (specifically, of both ends of the protective tube 81, the end closer to the resistance element 82) than the rearmost end of the resistance element 82, or may be located closer to the other end of the protective tube 81 (specifically, of both ends of the protective tube 81, the end farther from the resistance element 82) than the rearmost end of the resistance element 82. In particular, it is preferable that the rearmost end of the first portion 811 be located at the same position as the rearmost end of the resistance element 82, or closer to the other end of the protective tube 81 than the rearmost end of the resistance element 82. This is because it is possible to further increase heat conduction from the tread 3, which is the measurement target, to the resistance element 82.

[0044] The first portion 811 is made of a first material. The thermal conductivity of the first material is preferably 40 W / mK or more, more preferably 70 W / mK or more, and even more preferably 100 W / mK or more. If the thermal conductivity is 40 W / mK or more, the thermal conduction from the tread 3 to be measured to the resistance element 82 can be further increased. The thermal conductivity of the first material may be 150 W / mK or more, or may be 200 W / mK or more. On the other hand, the thermal conductivity of the first material may be, for example, 400 W / mK or less, 380 W / mK or less, or 350 W / mK or less.

[0045] Examples of the first material include pure copper and copper alloys. Examples of pure copper include electrolytic copper, oxygen-free copper, deoxidized copper, and vacuum-melted copper. Examples of copper alloys include iron-containing copper, chromium copper, cobalt copper, brass, bronze, cupronickel, nickel silver, phosphor bronze, aluminum bronze, silicon bronze, manganese bronze, beryllium copper, titanium copper, chromium copper, Causon alloy, zirconium copper, manganin, and Kelmet. Among these, iron-containing copper, chromium copper, and cobalt copper are preferred because of their high thermal conductivity and strength.

[0046] The second portion 812 is made of a second material. Examples of the second material include stainless steel. Examples of stainless steel include martensitic stainless steel, ferritic stainless steel, austenitic stainless steel, austenitic-ferritic stainless steel, and precipitation hardened stainless steel. Examples of the second material include pure copper and copper alloys. A description of pure copper and copper alloys will be omitted because they overlap with the description of pure copper and copper alloys in the first material. Therefore, the description of pure copper and copper alloys in the first material can also be used as a description of pure copper and copper alloys in the second material.

[0047] The thermal conductivity of the first material is greater than that of the second material. This results in excellent heat conduction from the tread 3 to the resistance element 82, and therefore excellent responsiveness of the temperature sensor 8 to temperature changes in the tread 3. As a result, the end point of vulcanization can be determined with high accuracy.

[0048] The difference between the thermal conductivity of the first material and the thermal conductivity of the second material (i.e., the thermal conductivity of the first material minus the thermal conductivity of the second material) is preferably 60 W / mK or more, more preferably 100 W / mK or more, and even more preferably 150 W / mK or more. A difference of 60 W / mK or more improves heat conduction from the tread 3 to the resistance element 82, thereby improving the responsiveness of the temperature sensor 8 to temperature changes in the tread 3. As a result, the end of vulcanization can be determined with greater accuracy. This difference may be, for example, 390 W / mK or less, 370 W / mK or less, or 350 W / mK or less.

[0049] A first portion 811 of the protective tube 81 protrudes from the protrusion 115. Specifically, the first portion 811 of the protective tube 81 protrudes from the tip of the protrusion 115. This makes it possible to embed the first portion 811 in the tread 3 of the green tire 9, and the temperature of the tread 3 can be measured with the first portion 811 embedded in the tread 3. Therefore, the temperature change of the tread 3 can be measured with excellent responsiveness. As a result, the end point of vulcanization can be determined with high accuracy.

[0050] More specifically, at least a portion of the second portion 812 of the protective tube 81 also protrudes from the protrusion 115. In this way, by having not only the first portion 811 but also at least a portion of the second portion 812 protrude from the protrusion 115, heat conduction from the protrusion 115 to the resistance element 82 can be reduced compared to when only the first portion 811 protrudes from the protrusion 115, and therefore the temperature change of the tread 3 can be measured with high accuracy. As a result, the end point of vulcanization can be determined with high accuracy.

[0051] The length L2 of the portion of the protective tube 81 that protrudes from the protrusion 115 (hereinafter sometimes referred to as the "protrusion height") is preferably 5 mm or more. On the other hand, the protrusion height L2 is preferably 20 mm or less, and more preferably 15 mm or less. This is because the smaller the protrusion height L2, the less likely it is that foreign matter (e.g., pebbles) will become caught in the hole formed in the groove of the pneumatic tire by the temperature sensor 8. In addition, the smaller the protrusion height L2, the more likely it is that damage to the temperature sensor 8 (for example, damage that may occur due to the load applied to the temperature sensor 8 when the temperature sensor 8 is inserted into the raw tire 9) can be reduced.

[0052] The ratio of the protrusion height L2 to the height L3 of the protrusion 115, i.e., L2 / L3, is preferably 0.15 to 1.00. That is, this ratio is preferably 15% to 100%. This ratio may be 90% or less, or may be 80% or less.

[0053] When the protrusion height L2 is 100%, the length L1 of the first portion 811 is preferably 20% or more, and more preferably 30% or more. When the length L1 is 20% or more, heat conduction from the tread 3 to be measured to the resistance element 82 is further improved, and the responsiveness of the temperature sensor 8 to temperature changes in the tread 3 is further improved. As a result, the end of vulcanization can be determined with greater accuracy. On the other hand, the length L1 of the first portion 811 is preferably 60% or less, and more preferably 50% or less. When the length L1 is 60% or less, heat conduction from the protrusion 115 to the resistance element 82 can be further reduced, and temperature changes in the tread 3 can be measured with greater accuracy. As a result, the end of vulcanization can be determined with greater accuracy. In this specification, "length L1" means the maximum length of the first portion 811 in the longitudinal direction of the temperature sensor 8.

[0054] The smaller the width W1 of the protective tube 81, the less noticeable holes formed in the grooves of the pneumatic tire, so in that sense, it is preferable that the width W1 of the protective tube 81 is smaller. On the other hand, the larger the width W1 of the protective tube 81, the more durable the temperature sensor 8 is, so in that sense, it is preferable that the width W1 of the protective tube 81 has a certain thickness. Taking these into consideration, the width W1 of the protective tube 81 is preferably 2 mm to 10 mm. In this specification, "width W1" means the maximum width of the protective tube 81. Therefore, when the protective tube 81 has a shape with a diameter, it means the maximum diameter of the protective tube 81.

[0055] The width W1 of the protective tube 81 is preferably 25% to 100% when the width W2 of the protrusion 115 is 100%. The width W1 may be 90% or less, or may be 80% or less. In this specification, "width W2" refers to the maximum width of the protrusion 115 in the tire width direction.

[0056] <3. Manufacturing method of pneumatic tire> The method for manufacturing a pneumatic tire in this embodiment includes a step of heat-vulcanizing a green tire 9 in a mold 10. Because the method for manufacturing a pneumatic tire in this embodiment includes this step, the temperature change of the green tire 9 during heat-vulcanization can be measured with excellent responsiveness. As a result, the end point of vulcanization can be determined with high accuracy.

[0057] In the method for manufacturing a pneumatic tire according to this embodiment, for example, a green tire 9 is set in a mold 10, and the green tire 9 is heated while being pressed against the inner surface of the mold 10, which is clamped by an inflated bladder 15. To heat the green tire 9, external heating, in which the green tire 9 is heated from the tire outer surface side using the heated mold 10, and internal heating, in which the green tire 9 is heated from the tire inner surface side using the bladder 15 to which at least a high-temperature heating medium is supplied, can be performed.

[0058] When the raw tire 9 is pressed against the inner surface of the mold 10 by the bladder 15, the tip of the temperature sensor 8 (specifically, the portion of the protective tube 81 of the temperature sensor 8 that protrudes from the protrusion 115) is inserted into the tread 3 of the raw tire 9, so that the temperature of the tread 3 can be measured by the temperature sensor 8 inserted into the tread 3 during heating and vulcanization.

[0059] In this manner, the raw tire 9 is heated and vulcanized, that is, the raw tire 9 is vulcanized and molded to obtain a pneumatic tire.

[0060] <4. Various modifications can be made to this embodiment> The present embodiment described above can be modified in various ways. For example, one or more of the following modifications can be selected and applied to the present embodiment described above.

[0061] In the above-described embodiment, the resistor element 82 is housed in the hole of the first part 811. However, the present embodiment is not limited to this configuration. For example, as shown in FIG. 4 , the resistor element 82 may be embedded in the first part 811 of the protective tube 81.

[0062] In the above-described embodiment, the temperature sensor 8 is configured to include only the protective tube 81 as a protective tube. However, this embodiment is not limited to this configuration. That is, the temperature sensor 8 may further include another protective tube. For example, as shown in FIG. 5 , the temperature sensor 8 may further include an outer protective tube 86. Preferably, the leading end of the outer protective tube 86 is located at the same position as the rear end of the first portion 811 of the protective tube 81 in the longitudinal direction of the temperature sensor 8, or is located closer to the other end of the protective tube 81 (the end of the protective tube 81 farthest from the resistance element 82) than the rear end of the first portion 811. For example, the outer protective tube 86 may extend in the longitudinal direction of the temperature sensor 8 from the side surface of the second portion 812 of the protective tube 81, with a gap between the side surface and the second portion 812. An air space may be provided between the outer protective tube 86 and the protective tube 81. This reduces heat conduction from the protrusions 115 to the resistance element 82, thereby enabling more accurate measurement of temperature changes in a tire during heat vulcanization.

[0063] In the above-described embodiment, the first portion 811 is adjacent to the second portion 812. However, this embodiment is not limited to this configuration. For example, a third portion (not shown) made of a third material may be provided between the first portion 811 and the second portion 812 and adjacent thereto. That is, the protective tube 81 may include the first portion 811 located closer to the tip of the protective tube 81, the second portion 812 located closer to the other end of the protective tube 81 than the first portion 811, and a third portion between the first portion 811 and the second portion 812 and adjacent thereto. A description of the third material will be omitted because it overlaps with the descriptions of the first material and the second material. Therefore, the descriptions of the first material and the second material can also be used as a description of the third material. The thermal conductivity of the third material may be greater or less than that of the first material. The thermal conductivity of the third material may be greater or less than that of the second material.

[0064] In the above-described embodiment, a configuration has been described in which not only the first portion 811 but also at least a part of the second portion 812 protrudes from the protrusion 115. However, this embodiment is not limited to this configuration. For example, only the first portion 811 may protrude from the protrusion 115.

[0065] In the above-described embodiment, the temperature sensor 8 is used to measure the temperature of the raw tire 9 during heat vulcanization. However, the present embodiment is not limited to this configuration. In other words, the temperature sensor 8 may be used to measure the temperature of rubber other than the raw tire 9. [Explanation of symbols]

[0066] 1...bead portion, 1a...bead core, 2...sidewall, 3...tread, 4...carcass, 5...belt layer, 6...tread rubber, 9...green tire, 10...mold, 11...tread mold, 12...lower mold, 13...upper mold, 14...center mechanism, 15...bladder, 16...center post, 17...upper clamp, 18...lower clamp, 21...medium supply path, 22...outlet, 23...heating medium supply source, 24...supply piping, 25...valve, 26...pressurized medium supply source, 28...valve, 31...medium discharge path, 32...recovery port, 33...blow valve, 34...discharge piping, 35...pump, 111...segment, 115...projection, 8...temperature sensor, 81...protective tube, 82...resistance element, 83...inner conductor, 811...first part, 812...second part, 86...outer protective tube

Claims

1. A tread mold for molding the tread of an unvulcanized tire is provided, The tread mold includes a plurality of segments divided in the tire circumferential direction, At least one of the segments has a protrusion for forming a groove in the tread of the unvulcanized tire and a temperature sensor for measuring a rubber temperature, the temperature sensor includes a resistance element and a protective tube that protects the resistance element; the protective tube comprises a first portion made of a first material and located on a tip side of the protective tube, and a second portion made of a second material and located on the other end side of the protective tube relative to the first portion, the thermal conductivity of the first material is greater than the thermal conductivity of the second material; At least the portion of the temperature sensor protrudes from the protrusion. Tire vulcanization mold.

2. The tire vulcanizing mold according to claim 1 , wherein at least a portion of the second portion of the temperature sensor also protrudes from the protrusion.

3. 3. The tire vulcanization mold according to claim 2, wherein the length of the portion of the protective tube protruding from the projection is 20% to 60% of the length of the portion of the protective tube protruding from the projection.

4. A method for manufacturing a pneumatic tire, comprising a step of heat-vulcanizing an unvulcanized tire in the tire vulcanizing mold according to any one of claims 1 to 3.

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