JP7649124B2 - Cost calculation system, method and program - Google Patents

Description

The present invention relates to a cost calculation system, method, and program.

There is a method in which a database is prepared in advance that stores data such as the cost of various parts, and when a user selects multiple parts for producing a finished product, the cost of the finished product is calculated based on the cost data of each part stored in the database (see, for example, Patent Document 1).

JP 2002-182732 A

Incidentally, the material costs of each component that makes up a tire may be managed as data. Also, a finite element model may be created to perform tire simulations.

The present invention aims to provide a system, method, and program that can calculate the cost of tires using such material cost data and finite element models.

A cost calculation system according to an embodiment has a database of data necessary for calculating the cost of a finished product, and a calculation unit that calculates the cost of the finished product using data from the database, wherein the database includes data on material costs for a plurality of materials, and the calculation unit calculates the cost of the finished product, which is a tire made of a plurality of tire constituent components made of different materials, and the calculation unit calculates the cost of the tire as a finished product using the volume of each tire constituent component determined based on a finite element model of the tire and the material costs of the materials of each tire constituent component stored in the database , wherein the finite element model is a two-dimensional model of a widthwise cross section of the tire, and the calculation unit calculates the volume of each tire constituent component when the two-dimensional model is expanded once in the circumferential direction of the tire, and calculates the cost of the tire using the volumes, and with respect to tread rubber, which is one of the tire constituent components, the calculation unit calculates the volume of the tread rubber by excluding the volume of grooves that do not appear in the two-dimensional model from the volume of the tread rubber when the two-dimensional model is expanded once in the circumferential direction of the tire .

In addition, a cost calculation method of an embodiment includes a step in which a computer executes a step of acquiring data necessary for cost calculation from a database, and a step of calculating a cost using the data acquired from the database, the database includes data on material costs for a plurality of materials, and the cost calculation method is a method in which the computer calculates the cost of a tire composed of a plurality of tire constituent members made of different materials, and the computer calculates the volume of each tire constituent member based on a finite element model of the tire, and calculates the material cost of each tire constituent member from the database as the data. The method is characterized by executing the steps of acquiring material costs and calculating the cost of the tire using the volume and material costs of each tire constituent component , wherein the finite element model is a two-dimensional model of a widthwise cross section of the tire, the computer calculates the volume of each tire constituent component when the two-dimensional model is expanded once in the circumferential direction of the tire, and calculates the cost of the tire using the volumes, and with regard to tread rubber, which is one of the tire constituent components, the computer calculates the volume of the tread rubber by excluding the volume of grooves that do not appear in the two-dimensional model from the volume of the tread rubber when the two-dimensional model is expanded once in the circumferential direction of the tire .

Moreover, the program of the embodiment is a program for causing a computer to execute the above-described method.

According to the cost calculation system, method, and program of the embodiment, the cost of a tire can be calculated using material cost data and a finite element model.

FIG. 1 is a diagram showing the configuration of a cost calculation system. A diagram showing the database configuration. FIG. 2 is a diagram showing a two-dimensional tire model. 1 is a flowchart of a cost calculation method.

The embodiment will be described with reference to the drawings. Note that the embodiment described below is merely an example, and any modifications that do not deviate from the spirit of the present invention are considered to be within the scope of the present invention.

The cost calculation system 10 of the embodiment is a system that calculates the cost of a tire based on a finite element model of the tire created for simulations or the like and the material costs of each tire component stored in a database. Here, tire components refer to components that make up the tire, such as tread rubber and sidewall rubber.

As shown in FIG. 1, the cost calculation system 10 of the embodiment is a computer system including a CPU 11, a memory 12, etc. An input device 30 such as a keyboard and an output device 31 such as a display are connected to the cost calculation system 10.

The memory 12 stores a program 13 for executing the cost calculation method of this embodiment, a database 14 in which data necessary for cost calculation is stored, and the like. The CPU 11 reads and executes the program 13 in the memory 12, thereby functioning as a model acquisition unit 16, a component volume calculation unit 17, and a cost calculation unit 18, which will be described later. The component volume calculation unit 17 and the cost calculation unit 18 can be collectively referred to as a calculation unit.

As shown in FIG. 2, database 14 stores the numbers of the materials (rubber) that make up the tire (hereinafter referred to as "compound numbers") and data such as the physical property values, density, and material cost of each material, linked together. Here, the physical property values include those required for simulations using a finite element model, such as Poisson's ratio and elastic modulus. The material cost is the price per unit weight of the material. Various types of rubber with different compositions are assumed as materials. The density and material cost data are used to calculate the cost of the tire, and the physical property values are used for finite element analysis.

The model acquisition unit 16 acquires a tire model. The tire model acquired here is a finite element model in which the tire is divided into a finite number of elements. For each element, an element number, a node number, a node coordinate, and material property values (e.g., density, Young's modulus, Poisson's ratio, etc.) can be set. The finite element model acquired by the model acquisition unit 16 can be one that has been created in advance for simulating a tire using finite element analysis.

The finite element model in this embodiment is a two-dimensional model of a tire widthwise cross section (hereinafter referred to as "tire two-dimensional model 20") as shown in FIG. 3. This tire two-dimensional model 20 is a model of one side in the tire width direction. However, a model in which both sides in the tire width direction are complete may also be obtained as the tire two-dimensional model.

The tire two-dimensional model 20 shows tire components such as beads 21, carcass plies 22, inner liner 23, belt 24, tread rubber 25, sidewall rubber 26, and rim strip 27. The tread rubber 25 also shows a main groove 28. In an actual tire, the main groove 28 goes around the tire circumferentially. The part of the tread rubber 25 between the two main grooves 28 and the part between the main groove 28 and the ground contact edge are called the land part.

Although not shown in the tire two-dimensional model 20, various grooves such as lateral grooves extending in the tire width direction and sipes closing within the land portions are formed in the land portions of an actual tire. The total volume Vq of the grooves not appearing in the tire two-dimensional model 20 relative to the volume _Vp of the tread rubber 25 assuming that there are no grooves ( _grooves other than the main grooves 28) not appearing in the tire two-dimensional model 20 is defined as the slit void ratio R. That is, the slit void ratio R is calculated by the following formula.

The component volume calculation unit 17 calculates the volume of each tire component based on the two-dimensional tire model 20 acquired by the model acquisition unit 16. The volume of each tire component is calculated by assuming that the two-dimensional tire model 20 is expanded once in the tire circumferential direction.

As an example, the volume of a tire component can be calculated using the following integral formula:

Here, x is the coordinate in the tire axial direction, a is the coordinate on the x-axis of the end of the tire constituent member on one side in the tire axial direction, b is the coordinate on the x-axis of the end of the tire constituent member on the other side in the tire axial direction, f(x) is a function that represents the curve of the tire constituent member on the tire axially outer side on the tire 2D model 20, and g(x) is a function that represents the curve of the tire constituent member on the tire axially inner side on the tire 2D model 20. For reference, f(x) and g(x) when calculating the volume of two belts 24 are shown in bold lines in Figure 3. The coordinate x is also shown in Figure 3.

As another example, there is a method of finding the three-dimensional volume of each element of the two-dimensional tire model 20 by rotating it once around the tire rotation axis, and then finding the volume of the tire constituent member by adding up the volumes of all the elements that make up the tire constituent member. Specifically, first, using the Pappus-Guldin theorem, the volume of each element on the two-dimensional tire model 20 when rotated once around the tire rotation axis is calculated using the following formula.

Here, _Rm is the distance from the tire rotation axis to the center of gravity of the m-th element, _Sm is the area of the m-th element, and _vm is the volume of the m-th element. The distance R from the tire rotation axis to the center of gravity of the element is found from the center of gravity coordinates, which are found from the nodal coordinates. The volume of each element found in this way is added together using the following formula to find the volume of the tire constituent member.

Here, j is the number of elements that make up the tire component.

When the two-dimensional tire model 20 is a model of only one side in the tire width direction, the volume of the tire constituent members can be calculated by doubling the volume V calculated by equations 2, 3, and 4. Also, when the two-dimensional tire model is a model of both sides in the tire width direction, the volume V calculated by equations 2, 3, and 4 is the volume of the tire constituent members.

Incidentally, when calculating the volume _Vt of the tread rubber 25, simply assuming that the two-dimensional model of the tread rubber 25 is expanded in the tire circumferential direction results in the calculation including the volumes of various grooves (e.g., lateral grooves and sipes) that do not appear in the two-dimensional model (i.e., the volume of portions where no rubber actually exists) in the volume of the tread rubber 25. To prevent this, the member volume calculation unit 17 calculates a more accurate volume of the tread rubber 25 by subtracting the volumes of the various grooves that do not appear in the two-dimensional model (the above _Vq ) from the volume of the tread rubber 25 calculated by expanding the tire two-dimensional model 20 once in the tire circumferential direction (the same volume as the above _Vp ).

Specifically, the member volume calculation unit 17 calculates the accurate volume _Vt of the tread rubber 25 by the following formula.

However, in practice, the slit void ratio R is often known, rather than the volume _Vq of each of the above-mentioned various grooves. Therefore, in this embodiment, the member volume calculation unit 17 calculates an accurate volume _Vt of the tread rubber 25 by the following formula.

The cost calculation unit 18 calculates the cost of the tire from the material cost of each tire constituent member read from the database 14 and the volume of each tire constituent member calculated by the material volume calculation unit 17. In detail, the cost calculation unit 18 calculates the cost of the tire constituent member by multiplying the volume of the tire constituent member by the material density and material cost of the tire constituent member, and calculates the cost of the tire by adding up the costs of all the tire constituent members. In other words, the cost of the tire is calculated by the following formula.

Here, Y is the cost of the tire (yen), _Vn is the volume of the nth tire constituent ( ^m3 ), _ρn is the material density of the nth tire constituent (kg/ ^m3 ), _cn is the material cost (yen/kg), and i is the number of tire constituents that make up one tire.

If database 14 stores only data on rubber components and does not contain data on materials other than rubber components such as steel cords and organic fiber cords, the exact cost of the tire cannot be calculated using equation 7 alone. In that case, a more accurate cost of the tire can be calculated by adding the cost of components other than rubber components to the cost Y calculated using equation 7.

The physical property values in database 14 are used during simulation using finite element analysis, but are not used when calculating the cost of the tire.

The method for calculating the cost of tires using the cost calculation system 10 described above will be explained with reference to the flowchart in Figure 4.

First, the model acquisition unit 16 acquires a two-dimensional tire model 20, which is a finite element model (S1). The two-dimensional tire model 20 is created, for example, from a two-dimensional CAD drawing of the tire and is stored in advance in the memory 12, etc.

Next, a compounding number is obtained from the database 14 for the two-dimensional tire model 20, which is a finite element model (S2). Specifically, the user operates the input device 30 to assign the compounding number stored in the database 14 to each element of the finite element model. This links each element to the physical property value, density, and material cost linked to the compounding number. Since there are multiple elements for one tire component, the same compounding number is assigned to multiple elements belonging to the same tire component. Note that the finite element model becomes available for simulation by assigning physical property values to each element. A description of the simulation will be omitted here.

Next, the member volume calculation unit 17 calculates the volume of each tire constituent member based on the tire two-dimensional model 20 acquired by the model acquisition unit 16 (S3). At this time, the member volume calculation unit 17 uses the slit void ratio R to calculate the accurate volume Vt of the tread rubber 25 from the volume _Vp of the tread rubber obtained by a calculation of developing the two-dimensional model in the tire circumferential direction, excluding the volume _Vq of various grooves that do not appear in the two-dimensional _model . The slit void ratio R is input by the user from the input device 30.

Next, the cost calculation unit 18 calculates the cost of the tire based on the volume, density, and material cost of each tire component (S4). At this time, the cost calculation unit 18 reads the cost of the material from the database 14 based on the compounding number assigned in step S2 and uses it for the calculation.

Next, the cost calculation unit 18 outputs the calculation result to the output device 31 (S5).

As described above, the cost calculation system 10 of this embodiment calculates the cost of a tire as a finished product using the volume of each tire component determined based on the finite element model of the tire and the material cost of each tire component stored in the database 14. This makes it possible to calculate the cost of a tire by utilizing the managed material cost data and the finite element model created for the simulation.

In addition, the finite element model of this embodiment is a two-dimensional model of the tire widthwise cross section, but the component volume calculation unit 17 calculates the volume of each tire component when the two-dimensional model is expanded once in the tire circumferential direction, thereby making it possible to calculate the volume of each tire component within the entire tire. The cost calculation unit 18 can then use this volume to calculate the cost of the tire. Therefore, even if only a two-dimensional model is available as the finite element model, the cost of the tire can be calculated. Also, since there is no need to create a three-dimensional model just to calculate the cost of the tire, the cost can be calculated in a short time.

The component volume calculation unit 17 also calculates the final volume of the tread rubber 25 from the volume of the tread rubber 25 when the two-dimensional model is expanded once in the tire circumferential direction, excluding the volume of grooves that do not appear in the two-dimensional model. This makes it possible to more accurately calculate the volume of the tread rubber 25, and therefore the cost price of the tire.

As described above, the cost calculation method of this embodiment includes the steps of determining the volume of each tire component based on a finite element model of the tire, obtaining the material cost of each tire component from database 14, and calculating the cost of the tire using the volume and material cost of each tire component. This method makes it possible to calculate the cost of the tire by utilizing managed material cost data and a finite element model created for the simulation.

Various modifications can be made to the above embodiment. Examples of modifications are described below.

<Modification 1>
The finite element model acquired by the model acquisition unit 16 may be a three-dimensional model of the entire tire. In this case, the member volume calculation unit 17 can calculate the volume of each tire component from the three-dimensional model without performing calculations to expand the two-dimensional model in the tire circumferential direction as in the above embodiment. In this case, the volume of grooves and land portions whose shapes change three-dimensionally, such as three-dimensional sipes whose shapes change in the depth direction, can be accurately calculated, and the volume of the tread rubber 25 can be accurately calculated.

<Modification 2>
There is no limitation on the specific form of use of the cost calculation system 10. For example, the cost calculation system 10 may be provided in a server, and a plurality of client computers may be connected to the server via a network, so that each client computer can calculate the cost of a tire.

<Modification 3>
In the above embodiment, the cost is calculated in yen, but the cost calculation unit 18 may calculate the cost in another currency. Also, the cost calculation unit 18 may calculate the cost in one currency and then convert it into another currency.

In addition, because each material is produced in a different country, the cost of one material may be expressed in yen and the cost of another material in dollars in the database 14, and so on. In such cases, the cost calculation unit 18 calculates the cost of the tire using the following formula.

Here, a _n is a coefficient for converting the currency of the cost (c _n ) of the nth tire constituent member into the currency of the cost (Y) to be calculated.

<Modification 4>
The method of calculating the cost of the tread rubber 25 is not limited to the method of calculating an accurate volume _Vt of the tread rubber 25 as in the above embodiment, and then multiplying _Vt by the material density _ρn and the material cost _cn .

For example, first, the component volume calculation unit 17 calculates the volume _Vp of the tread rubber 25 calculated by developing the tire two-dimensional model 20 in the tire circumferential direction. Next, the cost calculation unit 18 multiplies the volume _Vp by the material density _ρn and the material cost _cn to calculate a tentative cost _Y1 that ignores the presence of various grooves that do not appear in the tire two-dimensional model 20. Next, the cost calculation unit 18 calculates an accurate cost _Y2 by the following formula using the slit void ratio R.

<Modification 5>
The database 14 may also include data on materials other than rubber members, such as steel cords and organic fiber cords. In that case, the accurate cost of the tire can be calculated using the formula (7).

10...cost calculation system, 11...CPU, 12...memory, 13...program, 14...database, 16...model acquisition unit, 17...component volume calculation unit, 18...cost calculation unit, 20...tire two-dimensional model, 21...bead, 22...carcass ply, 23...inner liner, 24...belt, 25...tread rubber, 26...sidewall rubber, 27...rim strip, 28...main groove, 30...input device, 31...output device

Claims (3)

A cost calculation system having a database of data necessary for calculating the cost of a finished product, and a calculation unit that calculates the cost of the finished product using data from the database,
the database includes material cost data for a plurality of materials;
The calculation unit calculates a cost of the finished product, which is a tire made of a plurality of tire constituent members made of different materials,
the calculation unit calculates a cost of the tire as a finished product by using a volume of each tire constituent member obtained based on a finite element model of the tire and a material cost of each tire constituent member stored in the database ,
the finite element model is a two-dimensional model of a tire width direction cross section, the calculation unit calculates a volume of each tire constituent member when the two-dimensional model is expanded once in the tire circumferential direction, and calculates a cost of the tire using the volume;
With regard to tread rubber, which is one of the tire constituent components, the calculation unit determines the volume of the tread rubber by excluding the volume of grooves that do not appear in the two-dimensional model from the volume of the tread rubber when the two-dimensional model is expanded once in the circumferential direction of the tire . A cost calculation method, comprising the steps of: acquiring data necessary for cost calculation from a database; and calculating a cost using the data acquired from the database,
The database includes data on material costs for a plurality of materials;
The cost calculation method is a method in which the computer calculates a cost of a tire made of a plurality of tire constituent members made of different materials,
The computer,
determining a volume of each tire component based on a finite element model of the tire;
acquiring a material cost of each tire component as the data from the database;
Calculating the cost of the tire using the volume and material cost of each tire component;
The present invention is characterized in that :
the finite element model is a two-dimensional model of a tire width direction cross section, the computer calculates a volume of each tire component when the two-dimensional model is expanded once in the tire circumferential direction, and calculates the tire cost using the volume;
With regard to tread rubber, which is one of the tire constituent components, the computer calculates the volume of the tread rubber by subtracting the volume of grooves that do not appear in the two-dimensional model from the volume of the tread rubber when the two-dimensional model is expanded once in the circumferential direction of the tire . A program for causing a computer to execute the method of claim 2 .

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