JP6769180B2 - Raw tire temperature simulation method and tire vulcanization method - Google Patents

Description

The present invention relates to a simulation method for calculating the temperature and vulcanization amount of a raw tire and a vulcanization method for a tire.

Conventionally, in the step of vulcanizing a raw tire, a mold for forming the outer surface of the tire and a bladder that expands in the cavity of the raw tire set in the mold have been used. Raw tires are vulcanized and molded by heating and pressurizing between these molds and bladder.

A high-pressure gas containing water vapor is supplied to the internal space of the bladder. Due to the temperature drop in the internal space of the bladder, a part of the water vapor is condensed and stored in the internal space of the bladder as a drain. The drain is denser than the gas and therefore collects below the bladder. Further, since the drain and the gas transfer heat differently, there is a problem that vulcanization is hindered. Therefore, it is important to predict the temperature of the raw tire in consideration of the influence of the drain.

The following Patent Document 1 proposes a simulation method for performing heat conduction analysis of a raw tire in consideration of the influence of a drain. In this simulation method, a raw tire model in which a raw tire is modeled, a bladder model in which a bladder is modeled, and a drain model in which a drain is modeled are used.

Japanese Unexamined Patent Publication No. 2013-116583

In Patent Document 1, the material properties of rubber are input to the drain model in order to collectively analyze the heat conduction of the raw tire model, the bladder model and the drain model. However, the material properties of drain and rubber are very different. Therefore, the simulation method of Patent Document 1 has a problem that the temperature of the raw tire cannot be calculated accurately.

The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a temperature simulation method and a tire vulcanization method capable of accurately calculating the temperature of a raw tire.

In the present invention, a mold for forming the outer surface of a tire and a part of the water vapor are partially expanded in the inner space of the raw tire set in the mold by supplying a high-pressure gas containing water vapor. This is a method for calculating the temperature of the raw tire in the step of vulcanizing the raw tire using a bladder stored as a drain in a computer, and the computer has a finite number of the raw tire. A process of inputting a raw tire model modeled by the elements of, a process of inputting a drain model in which the drain is modeled by a finite number of elements, and a process of arranging the drain model in the lumen of the raw tire model. The step of defining the temperature of the mold on the outer surface of the raw tire model, the step of defining the temperature and heat transfer rate of the gas directly or indirectly on the lumen surface of the raw tire model, the above. The step of inputting the material properties of the drain into the drain model, the step of defining the temperature of the drain in the drain model, and the computer using the mold to set the temperature of the mold, the temperature of the gas, and the temperature of the drain. It is characterized by including a step of calculating the temperature of the raw tire model based on the above.

In the method for simulating the temperature of a raw tire according to the present invention, it is desirable that the material properties include at least one of thermal conductivity, density or specific heat.

In the method for simulating the temperature of a raw tire according to the present invention, a step of inputting a bladder model in which the bladder is modeled with a finite number of elements into the computer and arranging the bladder model in the lumen of the raw tire model. It is desirable to include the steps to be performed.

In the step of arranging the drain model in the temperature simulation method of the raw tire according to the present invention, it is desirable to arrange the drain model so as to be in contact with the internal space of the bladder model and the inner surface thereof.

In the method for simulating the temperature of a raw tire according to the present invention, the temperature of the gas is determined by the portion of the inner surface of the bladder model exposed in the internal space of the bladder model and the outer surface of the drain model. It is desirable to set it in the exposed portion in the internal space.

In the method for simulating the temperature of a raw tire according to the present invention, it is desirable that the inner surface of the bladder model is divided into a plurality of regions, and the temperature of the gas is different for each region.

In the method for simulating the temperature of a raw tire according to the present invention, the step of inputting the drain model includes the step of calculating the amount of the drain generated by the computer prior to the step of inputting the drain model. It is desirable to determine the size of the drain model based on the amount.

The present invention controls the temperature of the mold or the temperature of the gas based on the temperature of the raw tire model obtained by the temperature simulation method of the raw tire according to any one of claims 1 to 7. It is characterized by that.

The raw tire temperature simulation method of the first invention of the present application includes a step of arranging the drain model in the cavity of the raw tire model, a step of defining the temperature of the mold on the outer surface of the raw tire model, and a step of defining the raw tire model. The process of defining the temperature and heat transfer rate of a high-pressure gas containing water vapor, directly or indirectly on the lumen surface, the process of inputting the material properties of the drain into the drain model, and the process of inputting the temperature of the drain into the drain model. Includes process.

Further, the raw tire temperature simulation method of the first invention of the present application includes a step in which a computer calculates the temperature of the raw tire model based on the temperature of the mold, the temperature of the gas, and the temperature of the drain. There is. According to the raw tire temperature simulation method of the first invention of the present application as described above, the temperature of the raw tire can be calculated in consideration of the influence of the drain without actually vulcanizing the raw tire. ..

Moreover, in the raw tire temperature simulation method of the first invention of the present application, the material properties of the drain are defined in the drain model. Therefore, in the raw tire temperature simulation method of the first invention of the present application, the influence of drain is considered more accurately than the simulation method of Patent Document 1 in which the material properties of rubber are defined in the drain model. The temperature and amount of vulcanization of raw tires during vulcanization can be calculated accurately.

The tire vulcanization method of the second invention of the present application is the temperature of the mold or the temperature of the gas based on the temperature of the raw tire model obtained by the temperature simulation method of the raw tire of the first invention of the present application. Is in control. According to the raw tire temperature simulation method of the first invention of the present application, the temperature and vulcanization amount of the raw tire can be calculated accurately in consideration of the influence of the drain. Therefore, in the tire vulcanization method of the second invention of the present application, the temperature of the mold or the temperature of the raw tire can be controlled in consideration of the influence of the drain, so that uneven vulcanization of the tire can be prevented.

It is a perspective view which shows an example of the computer 1 which executes the simulation method of this embodiment. It is sectional drawing which shows an example of the tire to be evaluated. It is sectional drawing explaining an example of the process of vulcanizing a raw tire. It is a flowchart which shows an example of the processing procedure of the simulation method of this embodiment. It is a figure which shows an example of the mold model, the raw tire model, the bladder model and the drain model used in the simulation method of this embodiment. It is a flowchart which shows an example of the processing procedure of the arrangement process of this embodiment. It is a flowchart which shows an example of the processing procedure of the boundary condition definition process of this embodiment. FIG. 5 is a simplified diagram. It is a graph which shows the relationship between temperature and time about a 1st region and a 2nd region. It is a figure which shows an example of the mold model, the raw tire model and the drain model used in the simulation method of another embodiment of this invention. It is a flowchart which shows an example of the processing procedure of the simulation method of still another Embodiment of this invention. It is a graph which shows the relationship between the gauge pressure of an experimental example and a vulcanization time. (A) is a graph showing the relationship between the temperature of the center portion of the experimental example and the vulcanization time, and (b) is a graph showing the relationship between the temperature of the center portion of the example and the vulcanization time. (A) is a graph showing the relationship between the temperature of the maximum tire width portion of the experimental example and the vulcanization time, and (b) is a graph showing the relationship between the temperature of the maximum tire width portion of the example and the vulcanization time. is there.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The raw tire temperature simulation method of the present embodiment (hereinafter, may be simply referred to as “simulation method”) is a method for calculating the temperature of the raw tire in the step of vulcanizing the raw tire using a computer. is there.

FIG. 1 is a perspective view showing an example of a computer 1 that executes the simulation method of the present embodiment. The computer 1 includes a main body 1a, a keyboard 1b, a mouse 1c, and a display device 1d. The main body 1a is provided with a processing unit (CPU), a ROM, a working memory, a storage device such as a magnetic disk, and disk drive devices 1a1, 1a2 and the like. The storage device stores in advance a processing procedure (program) for executing the simulation method of the present embodiment.

FIG. 2 is a cross-sectional view showing an example of the tire 2 to be evaluated. The tire 2 of the present embodiment is configured as, for example, a pneumatic tire for a heavy load. The tire 2 is provided with a carcass 6 extending from the tread portion 2a through the sidewall portion 2b to the bead core 5 of the bead portion 2c, and a belt layer 7 arranged on the outer side of the carcass 6 in the tire radial direction and inside the tread portion 2a. Has been done.

The carcass 6 is composed of at least one carcass ply 6A, or one carcass ply 6A in the present embodiment. The carcass ply 6A has a main body portion 6a that reaches the bead core 5 of the bead portion 2c from the tread portion 2a through the sidewall portion 2b, and is connected to the main body portion 6a and is folded back from the inside to the outside in the tire axial direction. It includes a folded portion 6b. A bead apex rubber 8 extending outward in the radial direction of the tire from the bead core 5 is arranged between the main body portion 6a and the folded-back portion 6b. Further, the carcass ply 6A has a carcass cord arranged at an angle of, for example, 75 to 90 degrees with respect to the tire equator C.

An inner liner rubber 9 forming the inner surface of the tire 2 is provided on the inner surface of the carcass 6. The inner liner rubber 9 is made of, for example, a butyl rubber having excellent air permeability and prevents air leakage.

The belt layer 7 is composed of, for example, four belt plies 7A to 7D in which steel belt cords are arranged at an angle of, for example, 10 to 70 ° with respect to the tire circumferential direction. These belt plies 7A to 7D are provided with one or more points where the belt cords intersect each other between the plies.

Such a tire 2 is manufactured by vulcanizing and molding an unvulcanized raw tire in a mold according to a convention. FIG. 3 is a partial cross-sectional view illustrating an example of a step of vulcanizing a raw tire (hereinafter, simply referred to as a “vulcanization step”).

In the vulcanization step of the present embodiment, a mold 11 for molding the outer surface of the tire 2 and a bladder 12 expanding in the lumen of the raw tire 2L set in the mold 11 are used. The raw tire 2L is vulcanized and molded by heating and pressurizing between the mold 11 and the bladder 12. As a result, the tire 2 shown in FIG. 2 is manufactured.

The mold 11 can hold, for example, a pair of sidewall molding dies 13 and 13 having sidewall molding surfaces 13s, a tread molding die 14 having tread rubber molding surfaces 14s, and a pair of bead portions 2c of the raw tire 2L. The bead rings 15 and 15 are included. By fitting the sidewall molding die 13, the tread molding die 14, and the bead ring 15, a molding surface 11s capable of molding the outer surface 2o of the tire 2 is formed. Further, the mold 11 is provided with heating means (not shown) such as an electric heater.

The bladder 12 is made of an expandable rubber-like elastic body. A high-pressure gas 17 containing water vapor is supplied to the internal space 12s of the bladder 12 from a supply means (not shown). The water vapor includes not only water vapor obtained by evaporating water to become a gas, but also saturated water vapor in which an equilibrium state is established between water and water vapor, and superheated water vapor obtained by further heating saturated water vapor. As a result, the bladder 12 expands and the raw tire 2L is pressed against the molding surface 11s of the mold 11. The gas 17 may be an air-fuel mixture composed of water vapor mixed with at least one or a plurality of inert gases such as nitrogen. The temperature of the gas 17 is set to, for example, about 140 to 220 ° C.

When the water vapor contained in the gas 17 is cooled on the inner surface of the bladder 12, a part of the water vapor is condensed and stored as a drain 18 in the internal space 12s of the bladder 12. Since the drain 18 has lower heat transfer (interferes with heat conduction) than the gas 17, it interferes with vulcanization of the raw tire 2L. In the present embodiment, a mechanism (not shown) for discharging a predetermined amount or more of the drain 18 is provided.

In the simulation method of the present embodiment, the temperature of the raw tire 2L is calculated in consideration of the influence of the drain 18. FIG. 4 is a flowchart showing an example of the processing procedure of the simulation method of the present embodiment.

In the simulation method of the present embodiment, a mold model in which the mold 11 is modeled with a finite number of elements is input to the computer 1 (step S1). FIG. 5 is a diagram showing an example of a mold model, a raw tire model, a bladder model, and a drain model used in the simulation method of the present embodiment.

In step S1, based on the design data (for example, CAD data) of the mold 11 (shown in FIG. 3), the mold 11 can handle a finite number of elements F (i) (i = 1) that can be handled by the numerical analysis method. , 2, ...) to be modeled (discretized). As a result, the mold model 21 is set.

The mold model 21 of the present embodiment is a first mold model 23 that models the sidewall molding mold 13 (shown in FIG. 3) and a second mold model that models the tread mold 14 (shown in FIG. 3). Includes a model 24 and a third molded model 25 that models the bead ring 15 (shown in FIG. 3). By integrally combining the first molding mold model 23, the second molding mold model 24, and the third molding mold model 25, the molding surface 21s for molding the outer surface 30o of the raw tire model 30 is formed.

As the numerical analysis method, for example, a finite element method, a finite volume method, a difference method or a boundary element method can be appropriately adopted. In this embodiment, the finite element method is adopted. Further, as each element F (i), for example, a quadrilateral element or the like can be adopted in the case of a two-dimensional model, and a tetrahedral solid element or the like can be adopted in the case of a three-dimensional model. Each element F (i) is provided with a plurality of nodes. Each element F (i) has an element number, a node number, a node coordinate value, and material properties (rigidity, Young's modulus, thermal conductivity, density, specific heat, or heat) of the mold 11 (shown in FIG. 3). Numerical data such as expansion coefficient) is defined. For setting (modeling) such a mold model 21, for example, commercially available meshing software is used. The mold model 21 is stored in the computer 1.

In the simulation method of the present embodiment, a raw tire model in which the raw tire 2L (shown in FIG. 3) is modeled with a finite number of elements is input to the computer 1 (step S2). In step S2, based on the design data (for example, CAD data) of the mold 11 (shown in FIG. 3) and the tire 2 (shown in FIG. 2), a finite number of raw tires 2L can be handled by the numerical analysis method. It is modeled (discretized) by the elements G (i) (i = 1, 2, ...). As a result, the raw tire model 30 is set.

As the element G (i), the same element as the element F (i) of the mold model 21 is adopted. Each element G (i) includes an element number, a node number, a node coordinate value, and material properties (rigidity, Young's modulus, thermal conductivity, density, specific heat, or heat) of the raw tire 2L (shown in FIG. 3). Numerical data such as expansion coefficient) is defined. The raw tire model 30 is stored in the computer 1.

Next, in the simulation method of the present embodiment, a bladder model in which the bladder 12 (shown in FIG. 3) is modeled with a finite number of elements is input to the computer 1 (step S3). In step S3, the bladder 12 is modeled with a finite number of elements H (i) (i = 1, 2, ...) That can be handled by the numerical analysis method, based on the design data (for example, CAD data) of the bladder 12. It is made (discretized). As a result, the bladder model 22 is set. In FIG. 5, the bladder model 22 is shown in color so as to be easily distinguished from other models.

As the element H (i), the same elements as the element F (i) of the mold model 21 and the element G (i) of the raw tire model 30 are adopted. Each element H (i) has an element number, a node number, a node coordinate value, and material properties (rigidity, Young's modulus, thermal conductivity, density, specific heat, or thermal expansion) of the bladder 12 (shown in FIG. 3). Numerical data such as coefficients) are defined. The bladder model 22 is stored in the computer 1.

Next, in the simulation method of the present embodiment, a drain model in which the drain 18 is modeled with a finite number of elements is input to the computer 1 (step S4). In step S4, in the vulcanization step shown in FIG. 3, the drain 18 stored in the internal space 12s of the bladder 12 has a finite number of elements J (i) (i = 1, 2, ... ) Is modeled (discretized). As a result, the drain model 28 is set.

As the element J (i), the same element F (i) of the mold model 21 and the like are adopted. Thereby, the drain model 28 is defined as a solid with no flow. Further, in each element J (i), numerical data such as an element number, a node number, a node coordinate value, and a material property of the drain 18 (shown in FIG. 3) are defined. The material properties include at least one of thermal conductivity, density or specific heat, and in this embodiment all of thermal conductivity, density and specific heat. As a result, in step S7 described later, the calculation in consideration of the drain 18 can be performed. In the present embodiment, other material properties include, for example, a coefficient of thermal expansion.

The size of the drain model 28 is preferably set based on the amount of drain 18 generated in the internal space 12s of the bladder 12 in the vulcanization step shown in FIG. In this embodiment, a mechanism (not shown) for discharging a predetermined amount or more of the drain 18 is provided. Therefore, it is desirable that the size of the drain model 28 is set based on this constant amount. As a result, in the present embodiment, even if the drain model 28 is defined as a solid without flow, the calculation accuracy does not decrease. Moreover, since it is not necessary to consider the increase or decrease of the drain 18, the calculation time can be shortened. The drain model 28 is stored in the computer 1.

Next, as shown in FIG. 4, in the simulation method of the present embodiment, the raw tire model 30, the bladder model 22, and the drain model 28 are arranged in the internal space 21i of the mold model 21 (arrangement step). S5). FIG. 6 is a flowchart showing an example of the processing procedure of the arrangement step S5 of the present embodiment.

In the arrangement step S5 of the present embodiment, the raw tire model 30 is first arranged in the internal space 21i of the mold model 21 (step S51). In step S51, the outer surface 30o of the raw tire model 30 is brought into contact with the molding surface 21s of the mold model 21. A restraint condition for preventing misalignment may be defined between the outer surface 30o of the raw tire model 30 and the molding surface 21s of the mold model 21.

Next, in the arrangement step S5 of the present embodiment, the bladder model 22 is arranged in the lumen 30s of the raw tire model 30 (step S52). In step S52, the outer surface 22o of the bladder model 22 is brought into contact with the inner cavity surface 30i of the raw tire model 30. A restraint condition for preventing misalignment may be defined between the outer surface 22o of the bladder model 22 and the inner cavity surface 30i of the raw tire model 30.

Next, in the arrangement step S5 of the present embodiment, the drain model 28 is arranged in the cavity 30s of the raw tire model 30 (step S53). In step S53 of the present embodiment, the drain model 28 is arranged in the internal space 22s of the bladder model 22. Further, in step S53, the drain model 28 is arranged so as to be in contact with the inner surface 22i of the bladder model 22. In the present embodiment, it is arranged below the internal space 22s in the figure based on the actual position of the drain 18 stored in the internal space 12s of the bladder 12 shown in FIG. A constraint condition for preventing misalignment may be defined between the drain model 28 and the inner surface 22i of the bladder model 22.

Next, as shown in FIG. 4, in the simulation method of the present embodiment, a boundary condition for calculating the temperature of the raw tire model is defined in the computer 1 (boundary condition definition step S6). FIG. 7 is a flowchart showing an example of the processing procedure of the boundary condition definition step S6 of the present embodiment.

In the boundary condition definition step S6 of the present embodiment, first, the temperature of the mold is defined on the outer surface 30o of the raw tire model 30 (step S61). In step S61, the temperature of the mold 11 during vulcanization shown in FIG. 3 on the molding surface 11s is defined on the outer surface 30o of the raw tire model 30 shown in FIG. The temperature of the mold is stored in the computer 1.

The setting of the mold temperature is not limited to such an embodiment. For example, the temperature of the heating means may be defined in the element F (i) of the mold model 21 arranged at the position corresponding to the heating means (not shown) of the mold 11 shown in FIG. In this case, in step S7 described later, the heat generation of the mold model 21 is calculated, and the temperature of the mold is defined on the outer surface 30o of the raw tire model 30 via the molding surface 21s of the mold model 21. Since the temperature of such a mold is calculated based on the actual heating of the mold 11, the calculation accuracy can be improved.

Next, in the boundary condition definition step S6 of the present embodiment, the temperature and heat transfer coefficient of the gas are defined directly or indirectly on the lumen surface 30i of the raw tire model 30 (step S62). In step S62 of the present embodiment, in the vulcanization step shown in FIG. 3, the temperature and heat of the gas are taken into consideration in consideration of the portion in contact with the gas 17 (that is, the inner surface 12i of the bladder 12 and the outer surface 18o of the drain 18). The transmission rate is defined.

In step S62 of the present embodiment, first, of the inner surface 22i of the bladder model 22, the portion 41 exposed in the internal space 22s of the bladder model 22 (that is, the portion not covered by the drain model 28 or the mold model 21). The temperature and heat transfer coefficient of the gas are set in. Next, in step S62 of the present embodiment, the temperature and heat of the gas are applied to the portion 42 (that is, the portion that does not contact the inner surface 22i of the bladder model 22) exposed in the internal space 22s of the outer surface 28o of the drain model 28. The transmission rate is set. As a result, in step S62, the temperature and heat transfer coefficient of the gas are indirectly defined in the cavity surface 30i of the raw tire model 30 via the bladder model 22 and the drain model 28. The temperature of the gas can be set as appropriate. The temperature of the gas of this embodiment is set within the above range. The heat transfer coefficient of the gas can also be set as appropriate. The heat transfer coefficient of a gas may be predicted from the generation of latent heat when liquefied from water vapor, or may be obtained experimentally. Usually, the heat transfer coefficient in the air-fuel mixture or when water vapor is liquefied is 80 to 20000 W / (m ² · K). The temperature and heat transfer coefficient of the gas may be obtained by an air flow simulation performed in advance.

The temperature and heat transfer coefficient of the gas can be uniformly set in the exposed portions 41 and 42 in the internal space 22s. In the internal space 22s of the bladder 12, when water vapor and an inert gas having different temperatures and densities are mixed, a light gas is accumulated in the upper part and a heavy gas is accumulated in the lower part, so that the inner surface of the bladder 12 is accumulated. The temperature of 12i may not be constant. Therefore, in step S62, of the inner surface 22i of the bladder model 22, the exposed portion 41 of the bladder model 22 may be divided into a plurality of regions, and the gas temperature and heat transfer coefficient may be different for each region. .. This makes it possible to define the temperature and heat transfer coefficient of the gas based on the actual vulcanization process. FIG. 8 is a simplified view of FIG. In FIG. 8, the mesh of the elements is omitted.

As shown in FIG. 8, the exposed portion 41 of the bladder model 22 of the present embodiment is divided into an upper first region 41a and a lower second region 41b in the figure. The gas temperature and heat transfer coefficient set in each region 41a and 41b are set based on the results measured at the position of the inner surface 12i of the bladder 12 corresponding to each region 41a and 41b in the vulcanization step. Is desirable.

FIG. 9 is a graph showing the relationship between the temperature and time of the bladder corresponding to the first region 41a and the second region 41b. In this graph, the temperature of the gas in the first region 41a is set higher than the temperature of the gas in the second region 41b. As a result, the temperature of the gas can be defined based on the actual vulcanization step shown in FIG. 3, so that the simulation accuracy can be improved. The temperature and heat transfer coefficient of the gas are stored in the computer 1.

Next, as shown in FIGS. 5 and 7, in the boundary condition definition step S6 of the present embodiment, the drain temperature is defined in the drain model 28 (step S63). In step S63 of the present embodiment, the drain temperature is defined in each element J (i) constituting the drain model 28. The drain is liquefied from water vapor and accumulates, but immediately after liquefaction, the temperature is the same as that of water vapor. Therefore, it is desirable that the initial temperature of the drain is set to be the same as the temperature of the gas (water vapor).
Further, it may be set based on the measurement result of the drain 18 stored in the vulcanization shown in FIG. 3 and the result of the air flow simulation. The temperature of the drain is input to the computer 1.

Next, in the boundary condition definition step S6 of the present embodiment, the initial temperatures of the mold model 21, the raw tire model 30, and the bladder model 22 are defined (step S64). The initial temperature can be set as appropriate. The initial temperature of this embodiment is set to, for example, 40 to 90 degrees.

Next, in the simulation method of the present embodiment, the computer 1 calculates the temperature of the raw tire model 30 (step S7). In step S7, the temperature of the raw tire model 30 is calculated based on the mold temperature, the gas temperature and the heat transfer rate, and the drain temperature defined in the boundary condition definition step S6.

In the simulation method of the present embodiment, different material identifications are defined for the mold model 21, the raw tire model 30, the bladder model 22, and the drain model 28. Therefore, different heat conduction equations are applied to the mold model 21, the raw tire model 30, the bladder model 22, and the drain model 28.

Then, in step S7, heat conduction of the mold model 21, the raw tire model 30, the bladder model 22, and the drain model 28 is based on the mold temperature, the gas temperature and the heat transfer coefficient, and the drain temperature. The analysis is done. In step S7, the temperature of the element F (i) of the mold model 21, the temperature of the element G (i) of the raw tire model 30, the temperature of the element H (i) of the bladder model 22, and the element J of the drain model 28. The temperature of (i) is calculated for each unit time T (x). These temperatures are stored in the computer 1.

For the heat conduction analysis of the present embodiment, the same method as before is adopted. The heat conduction analysis can be calculated using commercially available finite element analysis application software such as Abaqus manufactured by Dassault Systems, LS-DYNA manufactured by LSTC, or NASTRAN manufactured by MSC. The unit time Tx can be appropriately set depending on the required simulation accuracy.

In the simulation method of the present embodiment, the drain model 28 is arranged in the cavity 30s of the raw tire model 30. In the drain model 28, the material properties of the drain 18 and the temperature of the drain 18 shown in FIG. 3 (that is, a temperature equal to or lower than the temperature of the gas 17) are defined. As a result, in the simulation method of the present embodiment, it is possible to calculate a state in which the temperature rises slowly and vulcanization does not proceed easily in the portion where the drain exists, as in the actual vulcanization step.

As described above, according to the simulation method of the present embodiment, the temperature of the raw tire 2L can be calculated in consideration of the influence of the drain 18 without actually vulcanizing the raw tire 2L.

Moreover, since the material properties of the drain 18 are defined in the drain model 28, for example, the influence of the drain 18 is affected as compared with the simulation method of Patent Document 1 in which the material properties of rubber are defined in the drain model 28. Can be considered more accurately. Therefore, in the simulation method of the present embodiment, the temperature of the raw tire 2L during vulcanization can be calculated accurately.

Further, in the simulation method of the present embodiment, the temperature of the raw tire model 30 is calculated based on the drain model defined as a solid without flow and the conditions of the temperature of the gas and the heat transfer coefficient. Therefore, in the simulation method of the present embodiment, for example, it is not necessary to carry out a fluid simulation in which the drain 18 and the gas 17 are modeled as a fluid, so that the calculation time can be shortened.

Further, in the simulation method of the present embodiment, different gas temperatures and heat transfer coefficients are set in the plurality of regions 41a and 41b in which the inner surface 22i of the bladder model 22 is divided, so that the actual vulcanization step can be performed. Based on the temperature and heat transfer coefficient of the gas can be defined. Therefore, in the simulation method of the present embodiment, the temperature of the raw tire 2L during vulcanization can be calculated more accurately.

Next, as shown in FIG. 4, in the simulation method of the present embodiment, the computer 1 determines whether or not a predetermined vulcanization end time has elapsed (step S8). If it is determined in step S8 that the vulcanization end time has elapsed (“Y” in step S8), the next step S9 is carried out. On the other hand, when it is determined that the vulcanization end time has not elapsed (“N” in step S8), the unit time T (x) is advanced by one (step S10), and steps S7 and S8 are repeated. Will be implemented. Thereby, the temperature of the raw tire model 30 can be calculated from the start of vulcanization to the end of vulcanization.

Next, in the simulation method of the present embodiment, the computer 1 determines whether the vulcanization conditions (that is, the boundary conditions such as the mold temperature or the gas temperature) are good based on the temperature of the raw tire model 30. (Step S9). In step S9, it is determined whether or not the vulcanization conditions are good based on the quality and productivity of the tire after vulcanization predicted from the temperature of the raw tire model 30 (shown in FIG. 5).

When it is determined in step S9 that the vulcanization conditions are good (“Y” in step S9), a series of processes of the simulation method is completed. On the other hand, when it is determined that the vulcanization conditions are not good, the vulcanization conditions are changed (step S11), and steps S7 to S10 are carried out again. As a result, the simulation method of the present embodiment can obtain good vulcanization conditions based on the temperature of the raw tire model 30.

In the simulation method of the present embodiment, the bladder model 22 is arranged in the cavity 30s of the raw tire model 30, but the simulation method is not limited to this mode. FIG. 10 is a diagram showing an example of a mold model, a raw tire model, and a drain model used in the simulation method of another embodiment of the present invention. In this embodiment, the same configurations as those in the previous embodiment are designated by the same reference numerals, and the description thereof may be omitted.

In this embodiment, the drain model 28 may be arranged in the cavity 30s of the raw tire model 30 without arranging the bladder model 22 (shown in FIG. 5) in the cavity 30s of the raw tire model 30. .. In this case, the drain model 28 is arranged so as to come into contact with the lumen surface 30i of the raw tire model 30. Further, the temperature and heat transfer coefficient of the gas are directly defined on the inner cavity surface 30i of the raw tire model 30.

In the simulation method for reproducing such a vulcanization method, the temperature of the raw tire 2L can be calculated in consideration of the influence of the drain 18 as in the previous embodiment. In this embodiment, the cavity surface 30i of the raw tire model 30 may be divided into a plurality of regions (not shown), and different gas temperatures and heat transfer coefficients may be defined for each region.

In the previous embodiments, the size of the drain model 28 is set based on a certain amount of drain 18 being discharged, but is not limited to such an embodiment. For example, the computer 1 may calculate the generated amount of the drain 18 in advance, and the size of the drain model may be determined based on the generated amount. FIG. 11 is a flowchart showing an example of a processing procedure of the simulation method of still another embodiment of the present invention. In this embodiment, the same configurations as those in the previous embodiment are designated by the same reference numerals, and the description thereof may be omitted.

In the simulation method of this embodiment, the computer 1 calculates the amount of drainage generated prior to the step S4 of inputting the drain model (step S12). The amount of drain generated may be calculated by airflow simulation. The airflow simulation can be performed by the same method as before.

In step S4 for inputting the drain model of this embodiment, the size of the drain model 28 is determined based on the amount of drain generated calculated in step S12. As described above, in the simulation method of this embodiment, the size of the drain model 28 can be approximated to the actual amount of the drain 18 generated in the vulcanization step shown in FIG. Therefore, in the simulation method of this embodiment, the influence of the drain 18 can be considered more accurately, and the temperature and the amount of vulcanization of the raw tire during vulcanization can be calculated accurately.

Further, when the amount of drain generated changes from moment to moment, the size of the drain model 28 may be changed in step S7. Thereby, the influence of the drain 18 can be considered more accurately.

Next, the tire vulcanization method of the present embodiment (hereinafter, may be simply referred to as “vulcanization method”) will be described. In the vulcanization method of the present embodiment, the temperature of the mold or the temperature of the gas is controlled based on the temperature of the raw tire model 30 obtained by the simulation methods so far.

In the vulcanization method of the present embodiment, the temperature of the mold or the temperature of the gas is controlled based on the good vulcanization conditions obtained by the simulation method shown in FIG. 4 or FIG. The temperature of the mold may be controlled by a control means (not shown) connected to a heating means (not shown) of the mold 11, or may be manually controlled by an operator. The temperature of the gas may also be controlled by a control means (not shown) connected to a supply means (not shown) or manually by an operator.

As a result, in the vulcanization method of the present embodiment, the temperature of the raw tire 2L can be satisfactorily controlled in consideration of the influence of the drain, so that uneven vulcanization can be prevented. Therefore, in the vulcanization method of the present embodiment, the quality of the tire 2 and the productivity of the vulcanization process can be surely improved.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified into various embodiments.

Raw tires were vulcanized and molded using the mold and bladder shown in FIG. 3 (experimental example). In the experimental example, gas (steam, nitrogen) was supplied to the internal space of the bladder based on the graph showing the relationship between the gauge pressure and the vulcanization time shown in FIG. Only steam was supplied for 5 minutes from the start of vulcanization. Nitrogen was supplied 5 minutes after the start of vulcanization.

Then, the measurement positions 51 and 52 of the center portion of the tread portion, the measurement positions 53 and 54 of the shoulder portion, the measurement positions 55 and 56 of the maximum tire width portion, and the measurement positions 57 and 58 of the bead apex end side shown in FIG. The temperature from the start of vulcanization to the end of vulcanization was measured at the measurement positions 59 and 60 of the bead portion. Further, in the experimental example, in the bladder shown in FIG. 3, the temperature of the portion corresponding to the first region and the second region shown in FIG. 8 was measured, and the first region and the second region shown in FIG. 9 were measured. A graph showing the relationship between temperature and time was obtained.

According to the processing procedure shown in FIG. 4, the temperature of the raw tire was calculated using a computer (Example). In the examples, the mold model, the raw tire model, the bladder model and the drain model shown in FIG. 5 were used. In the drain model of the example, the material properties of the drain were set.

In the example, the temperature of the mold of the following experimental example was set in the mold model. Further, as the temperature of the gas of the example, the temperature of the graph of FIG. 9 was set in the first part and the second part of the bladder model shown in FIG. Further, the heat transfer coefficient of the gas was set in the first part and the second part of the bladder model, respectively, based on the airflow simulation carried out in advance. The temperature of the second part was set in the exposed part of the drain model. In addition, the following drain temperatures were set in the drain model. Then, the temperature of the raw tire model was measured based on the temperature of the mold, the temperature of the gas and the heat transfer coefficient, and the temperature of the drain. The temperature of the raw tire model was measured at the positions corresponding to the measurement positions 51, 52, 55 and 56 of the experimental example shown in FIG. The common specifications are as follows.
Tire size: 9.00R20
Mold heating temperature: 155 ° C
Gas heat transfer:
0-5 minutes (water vapor): 100 W / (m ² · K)
After 5 minutes (water vapor + nitrogen): 80 W / (m ² · K)
Material properties of drain:
Thermal conductivity: 0.661W / (m ・ K)
Density: 1000g / cm ³
Specific heat: 4500 J / K ・ g
Initial temperature of drain: 200 ° C

The results of the test are shown in FIGS. 13 and 14. FIG. 13A is a graph showing the relationship between the temperature of the center portion (measurement positions 51 and 52) of the experimental example and the vulcanization time, and FIG. 13B is the temperature and vulcanization time of the center portion of the example. It is a graph which shows the relationship with. FIG. 14A is a graph showing the relationship between the temperature of the maximum tire width portion (measurement positions 55 and 56) of the experimental example and the vulcanization time, and FIG. 14B is the temperature of the maximum tire width portion of the example. It is a graph which shows the relationship between vulcanization time and vulcanization time.

As a result of the test, as shown in FIGS. 13 and 14, it was confirmed that the temperature of the tire model of the example was close to the temperature of the tire model of the experimental example. As shown in FIG. 13, since the drain model was not set at the measurement positions 51 and 52, the temperature difference between them was calculated to be small. On the other hand, as shown in FIG. 14, in the graph of the embodiment, the temperature rise rate of the temperature on the side where the drain is accumulated (measurement position 56) is calculated to be slower than the temperature on the opposite side (measurement position 55). It was. Therefore, in the example, the temperature of the raw tire could be calculated accurately in consideration of the influence of the drain.

S4 Step of inputting material properties of drain S53 Step of arranging drain model S7 Step of calculating temperature of raw tire model

Claims (8)

The mold that forms the outer surface of the tire and the supply of high-pressure gas containing steam expands in the cavity of the raw tire set in the mold, and a part of the steam is stored as a drain in the internal space. It is a method for calculating the temperature of the raw tire in the step of vulcanizing the raw tire using a bladder, using a computer.
A process of inputting a raw tire model in which the raw tire is modeled with a finite number of elements into the computer.
A step of inputting a drain model in which the drain is modeled with a finite number of elements into the computer.
A step in which the computer places the drain model in the lumen of the raw tire model.
A step of causing the computer to store the temperature of the mold defined on the outer surface of the raw tire model.
A step of causing the computer to store the temperature and heat transfer coefficient of the gas defined directly or indirectly on the lumen surface of the raw tire model.
A step of causing the computer to store the material properties of the drain defined in the drain model.
The step of inputting the temperature of the drain defined in the drain model to the computer , and
A method for simulating a temperature of a raw tire, wherein the computer includes a step of calculating the temperature of the raw tire model based on the temperature of the mold, the temperature of the gas, and the temperature of the drain.
The temperature simulation method for a raw tire according to claim 1, wherein the material property includes at least one of thermal conductivity, density or specific heat. A process of inputting a bladder model in which the bladder is modeled with a finite number of elements into the computer,
The method for simulating a temperature of a raw tire according to claim 1 or 2 , wherein the computer includes a step of arranging the bladder model in a cavity of the raw tire model. The temperature simulation method for a raw tire according to claim 3, wherein the step of arranging the drain model is to arrange the drain model so as to be in contact with the internal space of the bladder model and the inner surface thereof. The temperature of the gas is set on a portion of the inner surface of the bladder model exposed in the internal space of the bladder model and a portion of the outer surface of the drain model exposed in the internal space. 4. The method for simulating the temperature of a raw tire according to 4. The inner surface of the bladder model is divided into a plurality of regions.
The temperature simulation method for a raw tire according to claim 5, wherein the temperature of the gas differs for each region. The computer includes a step of calculating the amount of the drain generated prior to the step of inputting the drain model.
The raw tire temperature simulation method according to any one of claims 1 to 6, wherein the step of inputting the drain model is to determine the size of the drain model based on the generated amount. The feature is that the temperature of the mold or the temperature of the gas is controlled based on the temperature of the raw tire model obtained by the temperature simulation method of the raw tire according to any one of claims 1 to 7. How to vulcanize tires.

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