JP2017113996A - Die for tire vulcanization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die for tire vulcanization that has a thermal insulation structure to reduce influence of body temperature of the die for tire vulcanization and enables temperature measurement at a position near the surface of a processing point of a green tire while avoiding shortage of heat supply to the surface of the processing point during vulcanization.SOLUTION: A die 1 for tire vulcanization used in vulcanization of a green tire G is equipped with a die body 11 having a molding surface M touching the green tire G, a sheath thermocouple 2 that is installed in the inside of the die body 11 and has a temperature sensor 21 arranged on the molding surface M, and a thermal insulation layer 3 arranged between the die body 11 and the sheath thermocouple 2 so as to enclose the temperature sensor 21.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire vulcanization mold, and more particularly, adopts a heat shield structure that is less susceptible to the temperature of the mold body in the tire vulcanization mold, and processing points of a green tire during vulcanization. The present invention relates to a tire vulcanization mold that enables temperature measurement at a position close to the surface of a processing point while avoiding insufficient heat supply to the surface.

  When vulcanizing a green tire, various attempts have been made to measure the temperature of each part of the green tire in order to grasp the vulcanization status of the tire (see, for example, Patent Document 1). In the proposal of Patent Document 1, a temperature sensor that detects the temperature of a rubber product during vulcanization and a transponder that stores temperature data detected by the temperature sensor in a storage unit and transmits it as a response signal are embedded in the rubber product. The temperature of rubber products during vulcanization is measured. However, since the temperature measurement result of the obtained rubber product is transmitted after vulcanization by a transponder, the obtained temperature measurement result cannot be used for temperature adjustment during vulcanization.

  On the other hand, when measuring the temperature of a green tire, the body temperature of the mold used for vulcanization and the rubber surface temperature of the green tire (hereinafter referred to as the processing point temperature) are generally regarded as the same. However, in practice, there is a difference between the die body temperature and the processing point temperature of the green tire, and therefore it is necessary to measure the temperature at a position closer to the processing point surface. In addition, in order to accurately measure the processing point temperature, a structure that is not easily influenced by the body temperature of the mold is required.

  Here, as a method for measuring the processing point temperature without being influenced by the body temperature of the mold, a thermocouple (exposed type) sandwiched between the tire surface and the mold can be considered. Thereby, since temperature measurement at a position close to the tire surface can be performed, it can be expected to measure the tire surface temperature with high accuracy. However, in the actual production process, such a thermocouple is complicated to handle such as wiring, so the thermocouple has to be attached to the mold side, and is affected accurately by the temperature of the mold. It was difficult to measure the processing point temperature.

JP 2007-225552 A

  The object of the present invention is to adopt a heat shielding structure that is not easily affected by the body temperature of the tire vulcanization mold, and while avoiding insufficient heat supply to the surface of the processing point of the green tire during vulcanization, the processing point An object of the present invention is to provide a tire vulcanization mold that enables temperature measurement at a position close to the surface.

  In order to achieve the above object, a tire vulcanization mold according to the present invention is a mold body having a molding surface that comes into contact with the green tire in a tire vulcanization mold used when vulcanizing a green tire. A sheath thermocouple disposed inside the mold body and having a temperature sensing part disposed on the molding surface, and between the mold body and the sheath thermocouple so as to surround the temperature sensing part. And a heat shielding material layer disposed on the surface.

  In the present invention, in a tire vulcanization mold used when vulcanizing a green tire, a mold body having a molding surface that comes into contact with the green tire, and a temperature sensing device disposed inside the mold body. A vulcanization of a green tire is provided by providing a sheath thermocouple having a portion disposed on the molding surface and a heat shield layer disposed between the mold body and the sheath thermocouple so as to surround the temperature sensing portion. In addition, the temperature sensing part for measuring the processing point temperature becomes less susceptible to the temperature of the mold body, and the temperature at a position close to the molding surface of the green tire can be measured. As a result, measurement with high accuracy is possible.

  In the present invention, the thermal conductivity of the heat shield material layer at 200 ° C. is preferably 25 W / mk or less. Thereby, since the heat shielding material layer is made of a material having a relatively low thermal conductivity, it becomes possible to make the temperature sensitive part less susceptible to the temperature of the mold body.

  In this invention, it is preferable that the sensitivity with respect to the processing point temperature of the green tire by a temperature sensing part is 10 times or more of the sensitivity with respect to the temperature of the mold body. Thereby, it becomes possible to improve the accuracy of the temperature measured in the temperature sensing part.

  In the present invention, the diameter of the heat shielding material layer is preferably at least twice the diameter of the sheath thermocouple. Thereby, since the heat insulation performance of the heat insulation material layer is improved, it becomes possible to make the temperature sensitive part less susceptible to the influence of the temperature of the mold body.

  In the present invention, it is preferable that the diameter of the heat shielding material layer is 1/3 or less of the thickness of the portion in contact with the temperature sensitive portion in the green tire. If the heat shield layer is excessively thick, the heating capacity of the tire vulcanization mold will be reduced. Therefore, by setting the diameter of the heat shield layer to one third or less of the thickness of the green tire, The vulcanization process can be carried out without hindering the heating of the green tire.

  In this invention, it is preferable that the time constant of the temperature measured in the temperature sensitive part with respect to the processing point temperature of a green tire is 30 seconds or less. Thereby, it becomes possible to improve the accuracy of the temperature measured in the temperature sensitive part using the temperature sensitive part having a reaction rate required at the time of vulcanization of the green tire.

It is sectional drawing which shows typically the metal mold | die for tire vulcanization | cure of this invention. It is sectional drawing which shows typically the metal mold body of the metal mold | die for tire vulcanization | cure of this invention. It is sectional drawing which shows typically the sheath thermocouple used for the metal mold | die for tire vulcanization | cure of this invention. It is sectional drawing which shows typically the sheath thermocouple used for the metal mold | die for tire vulcanization | cure of this invention. It is a graph showing the responsiveness of the temperature sensitive part of the sheath thermocouple used for the tire vulcanization mold of the present invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a tire vulcanizing mold 1 according to the present invention, and shows a state in which a green tire G is pressed against a molding surface M of a mold body 11 by a bladder 5 during vulcanization in a vulcanizer 4. Yes. The green tire G is composed of a crown part G1, a side part G2, and a bead part G3.

  The tire vulcanization mold 1 includes a mold body 11 having a molding surface M that abuts against the crown portion G1 of the green tire G, and a temperature-sensitive portion 21 that is disposed inside the mold body 11 and has a molding surface M. And a heat shield layer 3 disposed between the mold body 11 and the sheath thermocouple 2 so as to surround the temperature sensing part 21.

  The mold body 11 is composed of three mold bodies 11A, 11B, and 11C. As shown in FIG. 2, the mold main body 11 </ b> A is formed with a hole 12 that penetrates the mold main body 11 </ b> A and reaches the molding surface M that contacts the green tire G. A space 13 in which the heat shielding material layer 3 is disposed is formed adjacent to the hole 12 in the vicinity of the molding surface M in the mold main body 11A. Examples of the material of the mold body 11 include iron and aluminum alloy.

  The sheath thermocouple 2 is disposed in the hole 12. As shown in FIG. 3, the sheath thermocouple 2 includes a metallic cylindrical sheath 22 and a thermocouple 23 held in the sheath 22. The thermocouple 23 includes a pair of electrodes 23A and 23B, and the tips of these electrodes 23A and 23B are joined to each other. And the junction of the tip of electrode 23A, 23B in the thermocouple 23 is the temperature sensing part 21. In addition, a lead wire 25 is connected to the thermocouple 23, and the lead wire 25 is drawn out of the mold body 11 </ b> A through the sheath 22.

  The electrodes 23A and 23B are made of different metal materials. Different metal materials used for the electrodes 23A and 23B can be appropriately selected from the types of metal materials described in JIS standards (JIS C 1602-1995, etc.). For example, the symbols K and T of the kind in the JIS standard can be mentioned. The electrodes 23A and 23B are covered with a grout 24 which is an insulator. As a material of the grout 24, for example, quartz glass or the like is used.

  The heat shield layer 3 is disposed in a space 13 formed in the vicinity of the molding surface M in the mold body 11A. Further, the heat shielding material layer 3 is disposed adjacent to the sheath thermocouple 2 and surrounds the temperature sensing part 21. The material of the heat shielding material layer 3 may be any material having a thermal conductivity smaller than that of the material of the mold body 11 (iron, aluminum alloy, etc.). For example, quartz glass or the like is used. In particular, the heat conductivity at 200 ° C. of the heat shielding material layer 3 is 25 W / mk or less, more preferably 5 W / mk or less. By making the thermal conductivity of the heat shield material layer 3 within the above range, the heat shield performance of the heat shield material layer 3 is improved, so that the influence of the temperature of the mold body 11 on the temperature sensitive portion 21 is further increased. It becomes possible to make it difficult to receive.

  In the tire vulcanization mold described above, in the tire vulcanization mold 1 used when vulcanizing the green tire G, a mold body 11 having a molding surface M that contacts the green tire G, The sheath thermocouple 2 disposed inside the mold body 11 and having the temperature sensing part 21 disposed on the molding surface M, and between the mold body 11 and the sheath thermocouple 2 so as to surround the temperature sensing part 21. By providing the disposed heat shielding material layer 3, the temperature sensing part 21 for measuring the processing point temperature during the vulcanization of the green tire G becomes less susceptible to the temperature of the mold body 11, and the green tire It becomes possible to measure the temperature at a position close to the molding surface M of G.

  In the present invention, when measuring the processing point temperature of the green tire G in the temperature sensing unit 21, sensitivity is used as an index representing the accuracy of the measured temperature. The higher the sensitivity to the processing point temperature of the green tire G by the temperature sensing unit 21 is, the higher the accuracy of the temperature measured by the temperature sensing unit 21 is.

  As the range of sensitivity in the present invention, the sensitivity to the processing point temperature of the green tire G by the temperature sensing portion 21 is preferably 10 times or more the sensitivity to the temperature of the mold body 11. That is, the difference between the temperature measured at the temperature sensing part 21 and the processing point temperature of the green tire G is defined as a temperature difference a, and the difference between the temperature of the mold body 11 and the temperature measured at the temperature sensing part 21 is defined as a temperature difference. When b is set, the ratio (b / a) of the temperature difference b to the temperature difference a is preferably 10 or more. For example, when the temperature of the mold body 11 is 100 ° C., the processing point temperature of the green tire G is 20 ° C., and the temperature measured at the temperature sensing portion 21 is 25 ° C., the ratio of the temperature difference b to the temperature difference a (b / A) is calculated as (100-25) / (25-20) and becomes 15.

  Thus, by using the sensitivity to the processing point temperature of the green tire G by the temperature sensing part 21, it can be used as an index of the accuracy of the temperature measured in the temperature sensing part 21, and the temperature sensing part 21 with higher sensitivity can be obtained. It becomes possible to improve the accuracy of temperature measurement.

FIG. 4 shows the diameter of the sheath thermocouple 2, the diameter of the heat shield layer 3, and the thickness of the green tire G. As shown in FIG. 4, the diameter of the sheath thermocouple 2 is Φ ₂ , the diameter of the heat shield layer 3 is Φ _3, and the thickness of the portion of the green tire G that is in contact with the temperature sensing portion 21 is the thickness t. To do. The thickness t of the green tire G is assumed to be perpendicular to the green tire G from the center position of the temperature sensing portion 21 and the length thereof is measured.

In this case, the diameter Φ ₃ of the heat shielding material layer 3 is preferably at least twice as large as the diameter Φ ₂ of the sheath thermocouple 2. Thus the diameter [Phi ₃ of the thermal barrier material layer 3 by not less than 2 times the diameter [Phi ₂ of sheathed thermocouple 2, in order to improve heat shielding performance of the thermal barrier material layer 3 is, the temperature sensing portion 21 On the other hand, the influence of the temperature of the mold body 11 can be made more difficult to be affected.

Further, it is preferable that the diameter [Phi ₃ of the thermal barrier material layer 3 is 1/3 or less of the thickness t of the site and the temperature sensing portion 21 abuts on the green tire G. Thus, by making the diameter Φ ₃ of the heat shield material layer 3 to be one third or less of the thickness t of the green tire G, the heat shield material layer 3 does not hinder heating the green tire G, It becomes possible to carry out the vulcanization process. Here, when the heat shielding material layer 3 is excessively thick, the heating ability of the tire vulcanization mold 1 is reduced.

  In the present invention, a time constant is used as an index representing the accuracy of the temperature measured in the temperature sensing unit 21. The time constant is the temperature difference between the temperature measured by the temperature sensing unit and the temperature measurement target before the temperature sensing unit is brought into contact with the temperature measurement target. The time until the temperature measured later in the temperature sensing part reaches 63.2% of the initial temperature difference is defined as the time.

  FIG. 5 is a graph showing the relationship between the temperature A measured at the temperature sensing unit 21 and the temperature B measured between the green tire G and the mold body 11. The temperature B is a temperature measured by installing a thermocouple between the green tire G and the mold body 11 (point X in FIG. 4). That is, the temperature B as compared with the temperature A is a processing point of the green tire G. Temperature. The vertical axis represents temperature T (° C.), and the horizontal axis represents time S (seconds).

  The upper diagram of FIG. 5 shows temperature changes of the temperature A and the temperature B from the start point when the green tire G is pressed against the molding surface M of the mold body 11 during vulcanization. As shown in the upper diagram of FIG. 5, the temperature A suddenly decreases at the same time as the mold body 11 contacts the green tire G, rises at a certain temperature, and then remains flat. It has become. On the other hand, the temperature B suddenly increases as soon as the mold body 11 contacts the green tire G, and then becomes the same temperature as the temperature A. Thus, when the green tire G is pressed against the molding surface M of the mold body 11 during vulcanization, it can be seen that heat is transferred from the mold body 11 to the green tire G.

Also, shown in figure 5, the temperature difference T _A is the initial temperature difference between the temperature A and temperature B before pressing the green tire G on the mold body 11 (referred to as 100% the initial temperature difference T _A) , the temperature difference T _B indicates the temperature difference to be 63.2% with respect to the initial temperature difference T _a. That is, when pressing the green tire G on the forming surface M of the mold body 11 during vulcanization, will the temperature difference is shrunk by machining point temperature of the green tire G rises, the time to reach the temperature difference T _B Time S1. The time S1 becomes a time constant of the temperature measured at the temperature sensing unit 21 with respect to the processing point temperature of the green tire G.

  1 to 4, it is preferable that the time constant of the temperature measured in the temperature sensing unit 21 with respect to the processing point temperature of the green tire G is 30 seconds or less. Thereby, it becomes possible to improve the accuracy of the temperature measured in the temperature sensing part 21 by using the temperature sensing part 21 having a reaction rate required when the green tire G is vulcanized.

  In the above-described embodiment, the case where the sheath thermocouple 2 is installed at the central portion of the mold body 11A and the temperature is measured has been described. However, the sheath thermocouple is applied to the portion of the mold body 11 where the temperature measurement is required. What is necessary is just to install the pair 2 suitably.

DESCRIPTION OF SYMBOLS 1 Tire vulcanization mold 11 Mold body 12 Hole 13 Space 2 Sheath thermocouple 21 Temperature sensing part 22 Sheath 23A, 23B Electrode 24 Grout 25 Lead wire 3 Heat shield layer 4 Vulcanizer 5 Bladder G Green tire G1 Crown Part G2 Side part G3 Bead part M Molding surface

Claims (6)

  In a tire vulcanization mold used when vulcanizing a green tire, a mold body having a molding surface that comes into contact with the green tire, and a temperature-sensitive portion disposed inside the mold body A tire comprising: a sheath thermocouple disposed on the molding surface; and a heat shielding material layer disposed between the mold body and the sheath thermocouple so as to surround the temperature sensing portion. Mold for vulcanization.   2. The tire vulcanization mold according to claim 1, wherein a thermal conductivity at 200 ° C. of the heat shielding material layer is 25 W / mk or less.   3. The tire vulcanization mold according to claim 1, wherein a sensitivity to a processing point temperature of the green tire by the temperature-sensing unit is 10 times or more a sensitivity to a temperature of the mold body.   The tire vulcanization mold according to any one of claims 1 to 3, wherein a diameter of the heat shielding material layer is twice or more a diameter of the sheath thermocouple.   The diameter of the said heat-insulating material layer is 1/3 or less of the thickness of the site | part which contact | abuts with the said temperature-sensitive part in the said green tire, The tire vulcanization | cure in any one of Claims 1-4 characterized by the above-mentioned. Mold.   The tire vulcanization mold according to any one of claims 1 to 5, wherein a time constant of a temperature measured at the temperature sensitive portion with respect to a processing point temperature of the green tire is 30 seconds or less.

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