JP7119554B2 - Method for creating raw tire component model and method for creating raw tire model - Google Patents

Description

The present invention relates to a method for creating a green tire member model and a green tire model using a computer.

Patent Literature 1 listed below proposes a method for creating a raw tire model using a computer. In the method disclosed in Patent Document 1, first, a reinforcing material model obtained by discretizing a reinforcing material such as a belt ply is input to a computer. The reinforcing material model includes a code model in which the reinforcing material cords are modeled using beam elements.

Next, in the method of Patent Document 1 below, a casing model and a tread ring model are input to a computer. The tread ring model includes a stiffener model. Then, in the method of Patent Document 1 below, a raw tire model is created by arranging a tread ring model outside the casing model and performing deformation calculations thereof.

JP 2015-225457 A

However, the shape of the raw tire model created by the method of Patent Document 1 is slightly different from the shape of the raw tire that is actually manufactured.

For example, in the process of actually forming a green tire, initial tension is applied to the cords of reinforcing materials such as plies from the viewpoint of preventing loosening and meandering of the cords when reinforcing materials are stacked. When the reinforcing material is superimposed on the green tire casing including the carcass ply and the like, the casing is tightened by the tension, which affects the shape change. Such initial tension has not been reproduced in previous stiffener models.

SUMMARY OF THE INVENTION The present invention has been devised in view of the actual situation as described above, and a main object of the present invention is to provide a method capable of accurately creating a raw tire member model and a raw tire model.

The present invention is a method for creating, using a computer, a model for numerical analysis of a raw tire molding member including at least one first member in which reinforcing cords are arranged, wherein the first member is discretized. inputting the obtained first member model into the computer, wherein the first member model includes a code model obtained by discretizing the reinforcing cord with elements having a plurality of nodes, wherein the method comprises: The method further includes defining a tensile stress in the code model of the first member model under a condition that restricts movement of the node.

In the method for creating a raw tire member model according to the present invention, the step of defining the tensile stress includes a step of constraining the movement of the nodes, and after the step of constraining the movements of the nodes, the longitudinal direction of the cord model. between the adjacent nodes, calculating the amount of thermal contraction associated with the temperature drop of the element; and calculating the tensile stress corresponding to the amount of thermal contraction.

In the method for creating a raw tire member model according to the present invention, the step of defining the tensile stress calculates the elongation of the element so that the distance between the adjacent nodes in the longitudinal direction of the cord model increases. calculating the tensile stress corresponding to the elongation; and constraining movement of the node after calculating the tensile stress.

In the method for creating a raw tire member model according to the present invention, the raw tire molding member further includes a second member to be superimposed on the first member, and the step of inputting the first member model includes the second Discretizing based on the shape of the first member before overlapping with the member, the method discretizing the second member based on the shape before overlapping with the first member. The method may further include inputting a model into the computer, and having the computer overlay the first member model and the second member model.

In the method for creating a raw tire member model according to the present invention, the step of defining the tensile stress may be performed before the step of overlapping.

In the method for creating a raw tire member model according to the present invention, the step of defining the tensile stress may be performed after the step of overlapping.

In the method for creating a raw tire member model according to the present invention, after the superimposing step, the computer releases the constraints of the nodes of the code model of the first member model so that the A step of allowing contraction deformation of the code model may be further included.

The present invention is characterized by including the step of creating a model for numerical analysis of a green tire using the green tire member model created by the method according to any one of claims 1 to 7.

The raw tire member model creation method of the present invention includes the step of inputting into a computer a first member model obtained by discretizing at least one first member in which reinforcing cords are arranged. The first member model includes a cord model obtained by discretizing the reinforcing cord with elements having a plurality of nodes. The method further includes the step of the computer defining tensile stresses in the code model of the first member model under conditions that constrain movement of the nodes.

By defining the tensile stress in the cord model, the first member model can reproduce the first member in which initial tension is applied to the reinforcement cords in the actual green tire molding process. Therefore, the method of the present invention can create a raw tire member model that can create a raw tire model with high accuracy.

1 is a perspective view showing an example of a computer for executing a raw tire member model creation method and a raw tire model creation method; FIG. It is a sectional view showing an example of a green tire. FIG. 4 is a partial perspective view of the first member; 4 is a flow chart showing an example of a processing procedure of a method for creating a raw tire member model; FIG. 4 is a conceptual diagram showing an example of a first member model and a second member model; FIG. 4 is an exploded perspective view showing part of the first member model; 4 is a flow chart showing an example of a processing procedure of a tensile stress definition step; FIG. 4 is a partial plan view showing an example of a code model in which tensile stress is defined; It is a flowchart which shows an example of the processing procedure of the tensile-stress definition process of other embodiment of this invention. (a) to (c) are plan views for explaining a tensile stress definition process according to another embodiment of the present invention. 4 is a flow chart showing an example of a processing procedure of a joining step; FIG. 4 is a conceptual diagram showing an example of a first member model and a second member model having portions that overlap each other; FIG. 4 is a conceptual diagram showing an example of a first member model and a second member model after deformation; FIG. 4 is a conceptual diagram showing an example of a first member model and a second member model that are in close contact with each other; 4 is a flow chart showing an example of a processing procedure of a method for creating a raw tire model; FIG. 2 is a conceptual diagram showing an example of a casing model that expands radially outward and a tread ring model. It is a conceptual diagram which shows an example of a raw tire model.

An embodiment of the present invention will be described below with reference to the drawings.
The method for creating a green tire member model according to the present embodiment (hereinafter sometimes simply referred to as the “first method”) is a method for creating a model for numerical analysis of a raw tire molding member using a computer. be. In addition, the raw tire model creation method of the present embodiment (hereinafter sometimes simply referred to as the "second method") uses the raw tire member model created by the first method for numerical analysis of the raw tire. A method for creating a model. FIG. 1 is a perspective view showing an example of a computer 1 for executing a raw tire member model creation method and a raw tire model creation method.

A 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 an arithmetic processing unit (CPU), a ROM, a work memory, a storage device such as a magnetic disk, disk drive devices 1a1 and 1a2, and the like. Note that the storage device pre-stores processing procedures (programs) for executing the first method and the second method of the present embodiment.

FIG. 2 is a cross-sectional view showing an example of a raw tire. The green tire 2 includes a plurality of green tire forming members (hereinafter sometimes simply referred to as "green tire members") 3 stacked on each other. The green tire member 3 of this embodiment includes at least one first member 5 in which reinforcing cords are arranged, and a second member 6 superimposed on the first member 5 . The first member 5 and the second member 6 are in an unvulcanized state. The term "unvulcanized" as used herein includes all modes that are not completely vulcanized, and the so-called semi-vulcanized state is included in this "unvulcanized".

The first member 5 of this embodiment is configured as a belt ply 7 . This belt ply 7 is overlaid on a carcass ply 6g and a cushion rubber 6h of the second member 6, which will be described later. The belt ply 7 includes an inner belt ply 7a and an outer belt ply 7b arranged outside the inner belt ply 7a in the tire radial direction. It should be noted that the belt ply 7 may include another belt ply (not shown) arranged radially outward of the outer belt ply 7b. Both axial end portions of the first member 5 of the present embodiment are covered with covering rubber 14 .

FIG. 3 is a partial perspective view of the first member 5. FIG. The first member 5 (inner belt ply 7 a and outer belt ply 7 b ) includes reinforcing cords 8 and topping rubber 9 covering the reinforcing cords 8 .

The reinforcing cords 8 are arranged at an angle θ1 of, for example, 10 to 40 degrees with respect to the tire circumferential direction. The reinforcing cords 8 of the inner belt ply 7a and the reinforcing cords 8 of the outer belt ply 7b are superimposed so as to cross each other. When another belt ply (not shown) is arranged outside the outer belt ply 7b, for example, reinforcing cords (not shown) arranged at an angle of 0 to 5 degrees with respect to the tire circumferential direction are provided. Further included. Although the reinforcing cords 8 of the present embodiment are configured as steel cords, they are not limited to such an aspect.

As shown in FIG. 2, the second member 6 of this embodiment includes a tread rubber 6a, a sidewall rubber 6b, a clinch rubber 6c, a bead apex rubber 6d, an inner liner rubber 6e, a bead core 6f, a carcass ply 6g, and A cushion rubber 6h is included.

In the tread portion 2a of the raw tire 2, the tread rubber 6a is arranged outside the outer belt ply 7b in the tire radial direction. The sidewall rubber 6b is arranged outside the carcass ply 6g in the tire axial direction in the sidewall portion 2b of the raw tire 2 . The clinch rubber 6c is fixed radially inward of the sidewall rubber 6b.

The bead apex rubber 6d extends outward in the tire radial direction from the bead core 6f. The inner liner rubber 6e is arranged on the inner surface of the carcass ply 6g. The cushion rubber 6h is arranged outside the carcass ply 6g in the buttress portion of the raw tire 2. As shown in FIG. The bead core 6f is formed by, for example, spirally winding a steel bead wire having a substantially rectangular cross section and covering it with unvulcanized rubber.

The carcass ply 6g extends from the tread portion 2a through the sidewall portion 2b to the bead core 6f of the bead portion 2c. The carcass ply 6g is formed by covering carcass cords (not shown) arranged at an angle of, for example, 75 to 90 degrees with respect to the tire equator C with unvulcanized topping rubber (not shown). .

In the process of molding the raw tire 2 (hereinafter referred to as the unit "molding process"), the first member 5 and the second member 6 are formed into an annular shape by a molding drum (not shown) or the like, as in the conventional molding process. The raw tire 2 is molded by being formed and superimposed on each other. In the molding process of the present embodiment, from the viewpoint of preventing slackness and meandering of the reinforcing cords 8 (shown in FIG. 3) of the first member 5, initial tension is applied to the reinforcing cords 8 when the second member 6 is stacked. The process of giving is being carried out. In the step of applying the initial tension, for example, the first member 5 is supplied when winding the first member 5 (in this embodiment, the inner belt ply 7a and the outer belt ply 7b) on a forming drum (not shown). This can be done by controlling the rotation speed of the rollers to be slower than the rotation speed of the forming drum.

FIG. 4 is a flow chart showing an example of a processing procedure of a raw tire member model creation method. FIG. 5 is a conceptual diagram showing an example of the first member model 11 and the second member model 12. As shown in FIG. A raw tire member model 10 includes a first member model 11 and a second member model 12 .

In the first method of the present embodiment, first, a first member model 11 obtained by discretizing the first member 5 (shown in FIG. 2) is input to the computer 1 shown in FIG. 1 (step S1). In step S1, discretization is performed based on the shape of the first member 5 before overlapping with the second member 6 shown in FIG. FIG. 6 is an exploded perspective view showing part of the first member model 11. FIG.

In step S1, first, the design data (for example, CAD data) of the first member 5 before forming the green tire 2 shown in FIG. 2 (that is, before overlapping with the second member 6) is shown in FIG. is input to the computer 1. The design data includes, for example, numerical data such as the cross-sectional shape of the first member 5 (the inner belt ply 7a and the outer belt ply 7b in this embodiment) shown in FIG. Then, in step S1, based on the design data of the first member 5, a finite number of elements (elements F(i) and elements G(i) shown in FIG. 6) that can be handled by numerical analysis are discretized. there is Thus, in step S1, a three-dimensional first member model 11 is set.

The first member model 11 includes an inner belt ply model 11a modeling the inner belt ply 7a (shown in FIG. 2) and an outer belt ply model 11b modeling the outer belt ply 7b (shown in FIG. 2). included. As shown in FIG. 6, the first member model 11 (inner belt ply model 11a and outer belt ply model 11b) of this embodiment includes a cord model 16, a topping rubber model 17, and a covering rubber model 18 (FIG. 5). ) are included.

The first member model 11 of this embodiment is formed in a thin plate shape having a thickness in the tire circumferential direction. Such a first member model 11 can reduce the number of elements F(i) compared to, for example, a model (not shown) that is continuous in the tire circumferential direction, and is therefore useful for shortening the calculation time.

The code model 16 is defined by discretizing the reinforcement code 8 (shown in FIG. 3) with a finite number of elements F(i) (i=1, 2, . . . ) each having a plurality of nodes 19 . Elements F(i) in this embodiment are defined as beam elements. The elements F(i) are assigned along the reinforcing cords 8 based on the arrangement of the reinforcing cords 8 . Thus, in step S1, the code model 16 can be set.

A beam element is a linearly defined one-dimensional element. Such beam elements, unlike two-dimensional shell elements and three-dimensional solid elements, allow calculation of the longitudinal tension and compression acting on each reinforcing cord 8 (shown in FIG. 3).

A finite element method, a finite volume method, a finite difference method, or a boundary element method, for example, can be appropriately employed as the numerical analysis method for the element F(i), and the finite element method is employed in this embodiment. Element F(i) includes the element number, coordinate values of node 19, and material properties (e.g., density, tensile stiffness, compression stiffness, shear stiffness, bending stiffness, torsional stiffness) of reinforcing cord 8 (shown in FIG. 3). , modulus of elasticity, or coefficient of thermal expansion along the longitudinal direction of the reinforcing cords 8), etc. are defined. Furthermore, the temperature (for example, 15 to 35° C.) at the time of manufacturing the raw tire 2 shown in FIG. 2 is set for the element F(i).

The topping rubber model 17 and the covering rubber model 18 (shown in FIG. 5) are a finite number of elements G(i) (i=1, 2, . . . ) that can be handled by numerical analysis. is defined by discretizing with Element G(i) in this embodiment is defined as a three-dimensional solid element.

As the numerical analysis method for the element G(i), the same method as for the element F(i) is adopted. Numerical data such as the element number, the number of the node 20, the coordinate values of the node 20, and material properties (for example, density, Young's modulus and/or damping coefficient) are defined for the element G(i). Further, the element G(i) is set to the temperature at which the green tire 2 shown in FIG. 2 is manufactured.

The topping rubber 9 and the covering rubber 14 (shown in FIG. 5) of this embodiment are made of unvulcanized rubber. The material properties of unvulcanized rubber are described, for example, in the literature (Hiroshi Harima, “Large deformation behavior of unvulcanized rubber under constant elongation speed”, Journal of Japan Rheology Society, Japan Rheology Society, 1976, Vol. .4, p.3-9) and literature (Chikao Tozaki, three others, "Green strength index, viscoelastic handling of yield stress", Journal of the Japan Rubber Association, Japan Rubber Association, 1969, 42, No. 6, p.433-438).

Next, in step S1, the cord model 16, the topping rubber model 17, and the covering rubber model 18 are integrally fixed based on the design data of the first member 5 shown in FIG. Thereby, in step S1, as shown in FIG. 5, the first member model 11 (inner belt ply model 11a and outer belt ply model 11b) can be defined. The fixation of the cord model 16 (shown in FIG. 6), the topping rubber model 17 (shown in FIG. 6), and the covering rubber model 18 includes contact conditions to prevent slipping through and fixation conditions to prohibit mutual relative movement. Boundary conditions are used.

The ends of the covering rubber model 18 are tapered. As a result, the first member model 11 and the second member model 12 can be brought into close contact without gaps in the joining step S4, which will be described later. The first member model 11 is stored in the computer 1 shown in FIG.

Next, in the first method of the present embodiment, the second member model 12 (shown in FIG. 5) obtained by discretizing the second member 6 (shown in FIG. 2) shown in FIG. 1 (step S2). The second member model 12 is set based on the shape of the second member 6 shown in FIG. 2 before being superimposed on the first member 5 .

In step S2, first, the design data (for example, CAD data) of the second member 6 before forming the green tire 2 shown in FIG. 2 (that is, before overlapping with the first member 5) is shown in FIG. is input to the computer 1. The design data includes, for example, numerical data such as the cross-sectional shape of the second member 6 (tread rubber 6a to cushion rubber 6h) shown in FIG. Then, in step S2, based on the design data of the second member 6, by discretizing with a finite number of elements H(i) (i=1, 2, . of the second member model 12 is set.

The second member model 12 includes a tread rubber model 12a discretized from the tread rubber 6a (shown in FIG. 2), a sidewall rubber model 12b discretized from the sidewall rubber 6b (shown in FIG. 2), and a clinch rubber 6c. (shown in FIG. 2) is included. The second member model 12 includes a bead apex rubber model 12d that discretizes the bead apex rubber 6d (shown in FIG. 2), an inner liner rubber model 12e that discretizes the inner liner rubber 6e (shown in FIG. 2), and a bead core model 12f that discretizes the bead core 6f (shown in FIG. 2). Further, the second member model 12 includes a carcass ply model 12g discretized from the carcass ply 6g (shown in FIG. 2) and a cushion rubber model 12h discretized from the cushion rubber 6h (shown in FIG. 2). .

In this embodiment, at least one of the end portions of the tread rubber model 12a, the sidewall rubber model 12b, the clinch rubber model 12c, the bead apex rubber model 12d, the inner liner rubber model 12e, the carcass ply model 12g, and the cushion rubber model 12h. The portions are each formed in a tapered shape. As a result, the second member model 12 and the first member model 11 can be brought into close contact without a gap in the joining step S4, which will be described later.

The second member model 12 of this embodiment is formed in a thin plate shape having a thickness in the tire circumferential direction. Such a second member model 12 can reduce the number of elements H(i) compared to, for example, a model (not shown) that is continuous in the tire circumferential direction, and is therefore useful for shortening the calculation time.

As the numerical analysis method for the element H(i), the same method as for the element F(i) and the element G(i) shown in FIG. 6 is adopted. Element H(i) is defined as a three-dimensional solid element, beam element, or the like. The element H(i) includes the element number, the number of the node 26, the coordinate values of the node 26, and the properties of the second member 6 shown in FIG. coefficients, etc.) are defined. Further, the element H(i) is set with the temperature at which the green tire 2 shown in FIG. 2 is manufactured. The material properties of the parts constituting the unvulcanized rubber are defined based on the above literature. The second member model 12 is stored in the computer 1 shown in FIG.

Next, in the first method of this embodiment, the computer 1 shown in FIG. stress definition step S3). FIG. 7 is a flow chart showing an example of the procedure of the tensile stress definition step S3. FIG. 8 is a partial plan view showing an example of the code model 16 in which the tensile stress S is defined.

In the tensile stress definition step S3 of this embodiment, first, the movement of the node 19 of the element F(i) of the code model 16 is constrained (step S31). In this embodiment, the movement of the node 19 is constrained by the boundaries that constrain the movement of the nodes 19, 19 along the longitudinal direction between the nodes 19, 19 arranged at both longitudinal ends of each element F(i). set by the conditions. Such boundary conditions allow deformation of the code model 16 and the first member model 11 including the code model 16 .

Further, the boundary conditions are such that the nodes 19, 19 at both ends in the longitudinal direction of each element F(i) are constrained only to move in the direction in which the distance L1 between the nodes 19, 19 becomes smaller than the original distance L1a. may Such a boundary condition allows movement in a direction in which the distance L1 between the nodes 19, 19 is greater than the original distance L1a, so that the code model 16 can be deformed more flexibly.

Next, in the tensile stress definition step S3 of the present embodiment, between the nodes 19, 19 adjacent in the longitudinal direction of the cord model 16, the thermal contraction amount due to the temperature drop of the element F(i) is calculated (step S32). . Step S<b>32 of this embodiment is performed after step S<b>31 of restraining the movement of the node 19 .

A temperature drop of the element F(i) is defined based on a predetermined first temperature and second temperature. As the first temperature, for example, the temperature at which the raw tire 2 is manufactured is set. The second temperature is set lower than the first temperature, for example, -10 to 10°C.

In step S32, the temperature of each element F(i) of the code model 16 is gradually lowered from the first temperature to the second temperature every minute time (simulation unit time) Tx (x=0, 1, . . . ). I am letting Accordingly, in step S32, the thermal contraction of each element F(i) is calculated based on the coefficient of thermal expansion defined for each element F(i).

The thermal contraction of each element F(i) acts in the direction of isotropic contraction of the volume without depending on the direction. Each element F(i) in this embodiment is a beam element. Therefore, the thermal contraction of each element F(i) acts in the longitudinal direction (contraction direction) of the code model 16 . Such thermal contraction can be calculated using, for example, commercially available finite element analysis application software such as LS-DYNA manufactured by JSOL.

In this embodiment, since the movement of the node 19 of each element F(i) is constrained, each element F(i) is thermally contracted (the distance L1 between the nodes 19, 19 is longer than the original distance L1a). smaller state) is not calculated. Therefore, in step S32, between the adjacent nodes 19, 19 of each code model 16, the amount of thermal contraction (thermal strain) associated with the temperature drop of the element F(i) is calculated.

Next, in the tensile stress definition step S3 of this embodiment, the tensile stress S corresponding to the amount of thermal contraction is calculated (step S33). In step S33, the amount of thermal shrinkage (thermal strain) is multiplied by the elastic modulus of the reinforcing cords 8 (shown in FIG. 3). Thereby, in step S33, the tensile stress S corresponding to the amount of thermal contraction can be calculated. A tensile stress S is defined for each element F(i) of the code model 16 .

As described above, in the tensile stress definition step S3 of the present embodiment, the tensile stress S can be defined in the code model 16 under conditions that restrict the movement of the node 19. FIG. As a result, the first member model 11 (shown in FIGS. 5 and 6) of the present embodiment can reproduce the actual first member 5 in which the initial tension is applied to the reinforcing cords 8 (shown in FIG. 3). can. Therefore, the first method of the present embodiment can create the raw tire member model 10 that enables creation of a raw tire model with high accuracy.

In the tensile stress definition step S3, after the tensile stress S is defined for each element F(i) of the code model 16, the temperature of each element F(i) is set to the first temperature (in this embodiment, the temperature of the green tire 2 manufacturing temperature) is preferably defined. This prevents the first method from defining temperature differences between the cord model 16 and the topping rubber model 17 and between the cord model 16 and the covering rubber model 18 (shown in FIG. 5). be able to.

In the tensile stress defining step S3 of the present embodiment, the tensile stress S of the cord model 16 is calculated based on the thermal contraction amount of the element F(i) due to the temperature drop, but the present invention is not limited to such a mode. FIG. 9 is a flow chart showing an example of the procedure of the tensile stress definition step S3 according to another embodiment of the present invention. FIGS. 10(a) to 10(c) are plan views for explaining the tensile stress definition step S3 of another embodiment of the present invention. In addition, in this embodiment, the same code|symbol may be attached|subjected about the structure same as an old embodiment, and description may be abbreviate|omitted.

In the tensile stress definition step S3 of this embodiment, the extension of the element F(i) is performed so that the distance L1 between the nodes 19, 19 adjacent in the longitudinal direction of the cord model 16 becomes large (larger than the original distance L1a). is calculated (step S34). In step S34 of the present embodiment, prior to the expansion calculation of each element F(i), as shown in FIG. distance L1a). This is because the distance L1 between the nodes 19 and 19 is restored to the original distance L1a by the extension calculation of the element F(i).

In this embodiment, the distance L1 between the nodes 19, 19 is reduced in consideration of the amount of change Lb (FIG. 10(c)) in the expansion calculation of the element F(i). At this time, the stress and the like of the element F(i) due to the contraction of the distance L1 between the nodes 19, 19 are not calculated.

The expansion of the element F(i) in this embodiment is performed by expansion calculation for expanding the cord model 16 outward in the tire radial direction. Therefore, in the present embodiment, the cord model 16 is arranged radially inward of the tire in consideration of expansion calculation. In this case, before placing the cord model 16 radially inward of the tire, it is desirable to set a boundary condition that allows the cord model 16 and the topping rubber model 17 (shown in FIG. 6) to overlap each other.

Next, in step S34, the extension of each element F(i) shown in FIG. 10(b) is calculated. As a result, in step S34, as shown in FIG. 10(c), the distance L1 between the nodes 19, 19 of the code model 16 can be restored to the original distance L1a shown in FIG. 10(a). .

As described above, the expansion of the element F(i) is performed by the expansion calculation that expands the cord model 16 outward in the tire radial direction. The expansion calculation of the code model 16 is performed by calculating the expansion of each element F(i) of the code model 16 between the nodes 19, 19 adjacent to each other in the longitudinal direction as the temperature rises. The temperature rise of the element F(i) is defined based on a predetermined first temperature (in this embodiment, the temperature at the time of manufacturing the raw tire 2) and a third temperature. The third temperature is set higher than the first temperature, for example, 40 to 60.degree.

In step S34, the temperature of each element F(i) of the code model 16 is gradually increased from the first temperature to the third temperature every minute time (simulation unit time) Tx. Accordingly, in step S34, the thermal expansion of each element F(i) is calculated based on the coefficient of thermal expansion defined for each element F(i). Such thermal expansion calculations can be calculated using the finite element analysis application software described above.

Each element F(i) in this embodiment is a beam element. Therefore, the thermal expansion of each element F(i) acts in the longitudinal direction (extending direction) of the code model 16 . Therefore, in step S34, the extension of each element F(i) can be calculated. As a result, in step S34, the length in the longitudinal direction and the position in the tire radial direction of the cord model 16 can be restored to the original length and position. After the elongation of each element F(i) is computed, boundary conditions are preferably set to prohibit the cord model 16 and topping rubber model 17 from overlapping each other.

Next, in the tensile stress definition step S3 of this embodiment, the tensile stress S corresponding to the elongation of the element F(i) is calculated (step S35). The tensile stress S is obtained by multiplying the strain of the element F(i) caused by the elongation of the element F(i) by the elastic modulus of the reinforcing cords 8 (shown in FIG. 3). The strain of the element F(i) is the extension of the element F(i) (longitudinal deformation between the nodes 19, 19) Lb+Lb (shown in FIG. 10(c)) to the element F(i) before extension. is obtained by dividing by the distance (original distance) L1a. A tensile stress S is defined for each element F(i) of the code model 16 .

Next, in the tensile stress definition step S3 of this embodiment, the movement of the node 19 of the element F(i) of the code model 16 is constrained (step S36). The step S36 of this embodiment is performed after the step S35 of calculating the tensile stress S. Restriction of movement of the node 19 can be performed by the same procedure as step S31 of the tensile stress definition step S3 of the previous embodiment shown in FIG.

As described above, in the tensile stress definition step S3 of this embodiment, the tensile stress S can be defined in the code model 16 under conditions that restrict the movement of the node 19, as in the previous embodiment. Thereby, the first member model 11 of this embodiment can reproduce the actual first member 5 in which the initial tension is applied to the reinforcing cords 8 (shown in FIG. 3). Therefore, the first method of this embodiment can create the raw tire member model 10 that can accurately create a raw tire model.

In the tensile stress definition step S3 of this embodiment, prior to calculating the elongation of the element F(i) in the step S34 of calculating the elongation of the element F(i), code Although the distance L1 in the longitudinal direction of the model 16 is made small (smaller than the original distance L1a), it is not limited to such a mode. For example, step S34 may calculate the elongation of element F(i) without reducing the longitudinal distance L1 of chord model 16 . In this case, in the step S36 of constraining the movement of the node 19, prior to constraining the movement of the node 19, the longitudinal distance L1 of the cord model 16 is returned to the original distance L1a (shown in FIG. 10(a)). is desirable.

Next, in the first method of the present embodiment, the computer 1 shown in FIG. 1 superimposes the first member model 11 and the second member model 12 shown in FIG. 5 (bonding step S4). FIG. 11 is a flow chart showing an example of the procedure of the joining step S4. FIG. 12 is a conceptual diagram showing an example of the first member model 11 and the second member model 12 having overlapping portions.

In the joining step S4 of the present embodiment, a first joined body model 31, a second joined body model 32, and a tread ring model 33 are set.

The first joint model 31 includes an inner liner rubber model 12e, a carcass ply model 12g, a clinch rubber model 12c, a sidewall rubber model 12b, and a cushion rubber model 12h. In the joining step S4, the first joined body model 31 can be defined by overlapping (joining) the inner liner rubber model 12e to the cushion rubber model 12h.

The second joint model 32 includes a bead core model 12f and a bead apex rubber model 12d. In the joining step S4, the second joined body model 32 can be defined by overlapping (joining) the bead core model 12f and the bead apex rubber model 12d.

The tread ring model 33 includes an inner belt ply model 11a, an outer belt ply model 11b, and a tread rubber model 12a. In the joining step S4, the tread ring model 33 can be defined by overlapping (joining) the inner belt ply model 11a, the outer belt ply model 11b, and the tread rubber model 12a.

In the joining step S4 of the present embodiment, first, the first member model 11 (the inner belt ply model 11a and the outer belt ply model 11b) and the second member model 12 (the tread rubber model 12a to the cushion rubber model 12h) are They are arranged under boundary conditions that allow mutual overlap (step S41).

As shown in FIG. 12, in step S41 of the present embodiment, first member models 11 (inner belt ply model 11a and outer belt ply model 11b) and second member models 12 (tread rubber model 12a to cushion rubber Model 12h), the first member 5 and the second member 6 are arranged so that the distance from the axis of the forming drum (not shown) for forming the first member 5 and the second member 6 in an annular shape (that is, the distance in the tire radial direction) is aligned. .

In step S41, the cross-sectional shape of each of the first member model 11 (the inner belt ply model 11a and the outer belt ply model 11b) and the second member model 12 (the tread rubber model 12a to the cushion rubber model 12h) is changed. The first member model 11 and the second member model 12 are arranged under boundary conditions that allow mutual overlap without any overlap. For this reason, the first member model 11 and the second member model 12 are provided with overlapping portions 34 (indicated by dashed lines in FIG. 12) that at least partially overlap each other.

The overlapping portions 34 of this embodiment are between the inner belt ply model 11a and the outer belt ply model 11b, between the carcass ply model 12g and the clinch rubber model 12c, and between the carcass ply model 12g and the sidewall rubber model 12b. is set between Note that the bead core model 12f and the bead apex rubber model 12d of the present embodiment are not provided with overlapping portions.

Next, in the joining step S4 of the present embodiment, the first member model 11 and the second member model 12 are deformed so that the overlapping portion 34 is eliminated (step S42). In step S42, the overlapping portion 34 is eliminated by moving the first member model 11 and the second member model 12 inward or outward in the tire radial direction. FIG. 13 is a conceptual diagram showing an example of the first member model 11 and the second member model 12 after deformation.

The method of moving the first member model 11 and the second member model 12 can be appropriately adopted. In step S42 of the present embodiment, the coefficients of thermal expansion defined for each element F(i), G(i) and H(i) and the temperatures set for the first member model 11 and the second member model 12 The first member model 11 and the second member model 12 are deformed (expanded or contracted) based on the amount of change.

In step S42, the temperatures of the elements F(i), G(i) and H(i) shown in FIGS. The temperature is gradually changed to the set temperature every minute time (simulation unit time) Tx. Accordingly, in step S42, based on the coefficient of thermal expansion defined for each element F(i), G(i) and H(i), each element F(i), G(i) and H(i) is calculated. Such thermal expansion and thermal contraction calculations can be calculated using the finite element analysis application software described above.

A temperature higher than the initial temperature is set for the outer belt ply model 11b and the tread rubber model 12a. As a result, in step S42, the expansion of the outer belt ply model 11b and the tread rubber model 12a can be calculated, so that the outer belt ply model 11b and the tread rubber model 12a can be moved outward in the tire radial direction. Therefore, in step S42, the overlapping portion 34 (shown in FIG. 12) between the inner belt ply model 11a and the outer belt ply model 11b can be eliminated. The element F(i) of the cord model 16 of the outer belt ply model 11b of this embodiment is allowed to move in the direction in which the distance between the nodes 19 increases. Therefore, in step S42, expansion deformation of the outer belt ply model 11b is allowed.

On the other hand, a temperature lower than the initial temperature is set for the clinch rubber model 12c and the sidewall rubber model 12b. As a result, in step S42, the contraction of the clinch rubber model 12c and the sidewall rubber model 12b can be calculated, so that the clinch rubber model 12c and the sidewall rubber model 12b can be moved inward in the tire radial direction. As a result, in step S42, overlapping portions 34 (shown in FIG. 12) between the carcass ply model 12g and the clinch rubber model 12c and between the carcass ply model 12g and the sidewall rubber model 12b can be eliminated. .

Next, in the joining step S4 of the present embodiment, the first member model 11 (the inner belt ply model 11a and the outer belt ply model 11b) and the second member model 12 (the tread rubber model 12a to the cushion rubber model 12h) are prepared. They are brought into close contact (step S43). In step S43, the first member model 11 and the second member model 12 are separated from each other by a gap under boundary conditions in which the first member model 11 and the second member model 12 are allowed to contact with each other and are prohibited from overlapping with each other. It is tightly attached without FIG. 14 is a conceptual diagram showing an example of the first member model 11 and the second member model 12 that are in close contact with each other.

In step S43 of the present embodiment, the first member model 11 and the second member model 12 (the outer belt ply model 11b, the tread rubber model 12a, the clinch rubber model 12c and the sidewall rubber model) are set to temperatures different from the initial temperature. 12b), the temperature of each element F (i), G (i) and H (i) is changed from a temperature different from the initial temperature to the initial temperature (temperature at the time of manufacturing the raw tire 2) for a minute time (simulation unit time) is gradually returned every Tx. As a result, in step S43, the contraction or expansion of the first member model 11 and the second member model 12 can be calculated. can be moved to Such thermal contraction and thermal expansion calculations can be calculated using the finite element analysis application software described above.

As described above, in step S43, the first member model 11 and the second member model 12 are set with boundary conditions that allow contact with each other and prohibit overlapping with each other. As a result, in step S43, the first member model 11 and the second member model 12 can be brought into close contact while preventing the overlapping portion 34 (shown in FIG. 12) of the first member model 11 and the second member model 12.

In step S43, the inner liner rubber model 12e, the carcass ply model 12g, the clinch rubber model 12c, the sidewall rubber model 12b, and the cushion rubber model 12h can be brought into close contact by calculating the expansion of the sidewall rubber model 12b and the cushion rubber model 12h. can. Boundary conditions for preventing relative movement are set between the inner liner rubber model 12e, the carcass ply model 12g, the clinch rubber model 12c, the sidewall rubber model 12b and the cushion rubber model 12h. As a result, in step S43, it is possible to set the first joint model 31 in which the inner liner rubber model 12e, the carcass ply model 12g, the clinch rubber model 12c, the sidewall rubber model 12b, and the cushion rubber model 12h are joined.

Furthermore, in step S43, the inner belt ply model 11a, the outer belt ply model 11b, and the tread rubber model 12a can be brought into close contact by the shrinkage calculation of the outer belt ply model 11b and the tread rubber model 12a. A boundary condition is set between the inner belt ply model 11a, the outer belt ply model 11b, and the tread rubber model 12a to prevent relative movement. Thus, in step S43, the tread ring model 33 obtained by joining the inner belt ply model 11a, the outer belt ply model 11b, and the tread rubber model 12a can be set.

In this embodiment, the nodes 19, 19 of the cord model 16 of the outer belt ply model 11b are constrained only to move in the direction in which the distance L1 between the nodes 19, 19 becomes smaller (that is, becomes smaller than the original distance L1a). ing. Therefore, even if the shrinkage calculation of the outer belt ply model 11b is performed, the original distance L1a between the nodes 19, 19 is maintained. c)) is maintained.

Furthermore, in step S43, a boundary condition is set between the bead core model 12f and the bead apex rubber model 12d to prevent relative movement. Thus, in step S43, it is possible to set the second joint model 32 in which the bead core model 12f and the bead apex rubber model 12d are joined. The first zygote model 31, the second zygote model 32 and the tread ring model 33 are stored in a computer.

In the first method of the present embodiment, the first member model 11 and the second member model 12 can be superimposed in the same manner as in the molding process of the actual raw tire 2 (shown in FIG. 2). Therefore, the first method of the present embodiment can create the raw tire member model 10 that enables creation of a raw tire model with high accuracy.

Next, in the first method of this embodiment, the computer 1 shown in FIG. 10(c)), the contraction deformation of the code model 16 of the first member model 11 is allowed (step S5). The step S5 of this embodiment is performed after the step of overlapping the first member model 11 and the second member model 12 (joining step S4).

In step S5, the boundary conditions constraining the movement of the nodes 19 (shown in FIGS. 8 and 10(c)) of the cord models 16 of the first member models 11 (inner belt ply model 11a and outer belt ply model 11b) is disabled. As a result, in step S5, based on the tensile stress S (shown in FIGS. 8 and 10(c)) defined for each element F(i), the tension between the nodes 19, 19 adjacent in the longitudinal direction of the cord model 16 is increased. A contraction deformation that reduces the distance L1 (original distance L1a) of is calculated.

In step S5, contraction deformation of the cord model 16 of the first member model 11 (the inner belt ply model 11a and the outer belt ply model 11b) is allowed, so that the length of the cord model 16 in the longitudinal direction is reduced. The one-member model 11 contracts radially inward. Due to the diameter reduction of the first member model 11, the tread rubber model 12a of the second member model 12 joined to the first member model 11 (inner belt ply model 11a and outer belt ply model 11b) is also reduced in diameter. As a result, in step S5, the tread ring model 33 can be reduced radially inward.

Such a tread ring model 33 can reproduce the raw tire member 3 (in this embodiment, the tread ring 23) deformed under the influence of the reinforcing cords 8 (shown in FIG. 3) to which initial tension is applied. can. Therefore, the first method of the present embodiment can create the raw tire member model 10 that enables creation of a raw tire model with high accuracy.

In the first method of the present embodiment, the tensile stress definition step S3 was performed before the step of overlapping the first member model 11 and the second member model 12 (joining step S4), but the present invention is not limited to such an aspect. . The tensile stress definition step S3 may be performed after the bonding step S4, for example. In this case, the tensile stress definition step S3 is based on the procedure shown in FIG. is preferably calculated. This is because, unlike the procedure shown in FIG. 9, the procedure shown in FIG. 7 does not require the calculation of radial contraction and expansion of the code model 16, thereby shortening the calculation time.

Next, a method (second method) for creating a raw tire model according to the present embodiment will be described. In the second method, a model for numerical analysis of a green tire is created using the raw tire member model created by the first method. FIG. 15 is a flow chart showing an example of a processing procedure of a raw tire model creation method.

In the second method of the present embodiment, first, a raw tire member model 10 (shown in FIG. 14) is created based on the first method shown in FIG. 4 (step S11). Next, in the second method of the present embodiment, a casing model 35 is set by closely contacting the first bonded body model 31 and the second bonded body model 32 shown in FIG. 14 (step S12). is expanded radially outward of the tire (step S13). FIG. 16 is a conceptual diagram showing an example of a casing model 35 that bulges outward in the radial direction.

In step S13, the bead portions 35c, 35c of the casing model 35 are moved inward in the tire axial direction so as to reduce the axial distance of the bead portions 35c, 35c of the casing model 35, and the casing model 35 is expanded outward in the tire radial direction. A deformation calculation is performed to The swelling of the casing model 35 is calculated based on the uniformly distributed load w1 defined on the inner surface of the casing model 35. As shown in FIG. The uniformly distributed load w1 is set based on the pressure of the high-pressure air that inflates the casing (not shown) of the raw tire 2 shown in FIG. The swelling of the casing model 35 allows the outer surface of the casing model 35 and the inner surface of the tread ring model 33 to come into contact with each other.

Next, in the second method of the present embodiment, the tread ring model 33 (shown in FIG. 14) is deformed toward the casing model 35 (step S14). Deformation of the tread ring model 33 is calculated based on a uniformly distributed load w2 defined on the outer surface of the tread ring model 33 . The uniformly distributed load w2 is set based on the pressure of a stitching roller (not shown) that presses the outer peripheral surface of the tread ring (not shown) of the green tire 2 shown in FIG. Thereby, in step S14, the deformation calculation of the tread ring model 33 can be performed so that the inner surface of the tread ring model 33 follows the outer surface of the casing model 35. FIG.

Next, in the second method of the present embodiment, the protruding portion 35o of the casing model 35 protruding axially outside the bead core model 12f is rolled up around the bead core model 12f (step S15). In step S15, the protruding portion 35o of the casing model 35 is rolled up based on the uniformly distributed load w3 defined on the inner surface of the protruding portion 35o. The uniformly distributed load w3 is set based on the pressure of a bladder (not shown) that presses against the inner surface of the protruding portion (not shown) of the raw tire 2 shown in FIG.

In step S15, deformation calculations are performed for the protruding portion 35o rolled up and the bead apex rubber model 12d so that the outer surface of the protruding portion 35o is in close contact with the outer surface of the carcass ply model 12g or the outer surface of the tread rubber model 12a. be. As a result, in step S15, the first member model 11 (the inner belt ply model 11a and the outer belt ply model 11b) and the second member model 12 (the tread rubber model 12a to the cushion rubber model 12h) are brought into close contact with each other without gaps. be able to.

Next, in the second method of the present embodiment, the first member model 11 (the inner belt ply model 11a and the outer belt ply model 11b) and the second member model 12 (the tread rubber model 12a to the cushion rubber model 12h) are The close contact state is maintained so that they are not separated from each other (step S16). In step S16, a boundary condition for preventing relative movement is set on the contact surface between the first member model 11 and the second member model 12 that are in close contact with each other. As a result, a raw tire model 36 is created. FIG. 17 is a conceptual diagram showing an example of the raw tire model 36. As shown in FIG.

In this embodiment, due to the contraction deformation of the cord model 16 (shown in FIGS. 8 and 10(c)) in step S5, the reinforcement cord 8 to which the initial tension is applied shown in FIG. A tread ring 23 (green tire member 3) is reproduced. By bringing such a tread ring model 33 into close contact with the casing model 35 (shown in FIG. 16), the casing model 35 holds the casing (not shown) tightened by the initial tension of the reinforcing cords 8 shown in FIG. can be reproduced. Therefore, in the second method of the present embodiment, since it is possible to consider the shape change of the green tire 2 due to the tightening of the casing by the reinforcing cords 8, the shape of the actual raw tire 2 (shown in FIG. 2) can be accurately determined. A reproduced raw tire model 36 can be created. The raw tire model 36 is stored in the computer 1 shown in FIG.

Next, in the second method of the present embodiment, it is determined whether or not the shape of the raw tire model 36 is good (step S17). The entity that makes the determination is not particularly limited, and may be determined by, for example, the computer 1 shown in FIG. 1 or an operator.

In step S17, if it is determined that the green tire model 36 has a good shape ("Y" in step S17), a green tire is manufactured based on the design data of the green tire member 3 (step S18). . On the other hand, if it is determined that the shape of the green tire model 36 is not good (“N” in step S17), the design data of the green tire member 3 is changed (step S19), and steps S11 to S17 are performed again. be done.

In the first method and the second method of the present embodiment, the green tire model 36 that accurately reproduces the shape of the actual green tire 2 (shown in FIG. 2) can be created. Good or bad can be determined with high accuracy. Thus, in the second method of the present embodiment, it is possible to reliably manufacture a green tire 2 having a good shape.

In this embodiment, as shown in FIG. 4, after the joining step S4 of overlapping the first member model 11 and the second member model 12, the first member model 11 (the inner belt ply model 11a and the outer belt ply model 11b) Although the step S5 is performed to allow the contraction deformation of , the present invention is not limited to such a mode. The step S5 of allowing contraction deformation of the first member model 11 is performed in the second method of creating the raw tire model shown in FIG. It may be performed after the step S16 of maintaining the close contact state. In such a second method, it is possible to create a green tire model 36 that considers the change in shape of the green tire 2 due to the tightening of the casing (not shown) by the reinforcing cords 8 .

Although the particularly preferred 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 in various ways.

A green tire (shown in FIG. 2) including at least one first member (shown in FIGS. 2 and 3) in which reinforcing cords are arranged was manufactured (experimental example). The reinforcing cords in the experimental example were given an initial tension that produced an elongation of 0.7%.

Using a computer, a model for numerical analysis of a raw tire molding member including at least one first member having reinforcing cords arranged thereon was created (Example and Comparative Example). In the embodiment, the tensile stress was defined in the code model of the first member model under the condition of restraining the movement of the nodes based on the processing procedure shown in FIGS. 4 and 8 . Tensile stress was defined based on the initial tension applied to the reinforcement cords of the experimental examples.

Next, in the embodiment, the first member model and the second member model are overlapped based on the processing procedure shown in FIG. 11, and the step of allowing the contraction deformation of the code model of the first member model was performed. Then, in the example, a raw tire model was created based on the processing procedure shown in FIG.

On the other hand, in the comparative example, no tensile stress was defined in the code model of the first member model. Then, the first member model and the second member model were superimposed to create a raw tire model.

Then, the tire circumferential length of the tread central portion of the raw tire models of the example and the comparative example was compared with the tire circumferential length of the tread central portion of the experimental raw tire model. Common specifications, etc. are as follows, except for those described in the specification.
Tire size: 275/40ZR18
First member: inner belt ply, outer belt ply Test results are shown in Table 1.

As a result of the test, the length of the tread center portion of the example was closer to the length of the tread center portion of the experimental example than the length of the tread center portion of the comparative example. Therefore, in the example, the raw tire member model and the raw tire model could be created with higher accuracy than in the comparative example.

S1 Step of inputting the first member model S3 Step of defining the tensile stress in the code model of the first member model

Claims (8)

A method for creating, using a computer, a numerical analysis model of a raw tire molding member including at least one first member in which reinforcing cords are arranged, comprising:
inputting a first member model obtained by discretizing the first member into the computer;
The first member model includes a code model obtained by discretizing the reinforcing cord with elements having a plurality of nodes,
The method further includes defining, in the code model of the first member model, a tensile stress under conditions that constrain movement of the node.
How to create a raw tire component model. defining the tensile stress constrains movement of the node;
After the step of constraining the movement of the nodes, calculating the thermal contraction amount due to the temperature drop of the element between the nodes adjacent in the longitudinal direction of the code model;
2. The method of creating a raw tire member model according to claim 1, further comprising the step of calculating said tensile stress corresponding to said amount of thermal shrinkage. The step of defining the tensile stress includes calculating the elongation of the element such that the distance between adjacent nodes in the longitudinal direction of the cord model increases;
calculating the tensile stress corresponding to the elongation;
2. The method of creating a green tire member model according to claim 1, further comprising a step of constraining movement of said nodes after said step of calculating said tensile stress. The green tire molding member further includes a second member that is superimposed on the first member,
The step of inputting the first member model includes the step of discretizing based on the shape of the first member before overlapping with the second member,
The method includes inputting a discretized second member model into the computer based on a shape of the second member before being superimposed on the first member;
4. The raw tire member model creation method according to claim 1, further comprising the step of causing said computer to overlap said first member model and said second member model. 5. The method of creating a raw tire member model according to claim 4, wherein the step of defining said tensile stress is performed before said step of overlapping. 5. The method of creating a raw tire member model according to claim 4, wherein the step of defining the tensile stress is performed after the step of overlapping. The method includes, after the superimposing step, the step of allowing the code model of the first member model to contract and deform by releasing the constraints of the nodes of the code model of the first member model by the computer. The method for creating a raw tire member model according to any one of claims 4 to 6, further comprising: Using the green tire member model created by the method according to any one of claims 1 to 7, creating a model for numerical analysis of the green tire,
How to create a raw tire model.

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