How to create a tire model

Abstract

In creating tire models, we aim to create more accurate numerical analysis models that reflect the shape of actual tires. [Solution] The tire model creation method includes the steps of: taking a photograph of the cross-section of an actual tire corresponding to the tire to be analyzed and obtaining cross-sectional data including the cross-sectional contour from the photographed image of the cross-section (S20); modifying the design drawing of the tire to be analyzed to match the obtained cross-sectional contour (S30); and creating a numerical analysis model of the tire to be analyzed based on the modified design drawing (S40). The modification step involves matching either the outer or inner surface shape of the obtained cross-sectional contour with the corresponding contour shape of the design drawing, and changing the thickness of the rubber material in the design drawing according to the difference between the thickness of the contour shape in the design drawing and the thickness of the measured cross-sectional contour, thereby matching the corresponding contour shape in the design drawing with the other shape of the cross-sectional contour, and thus reflecting the cross-sectional contour of the actual tire in the design drawing.

Description

Technical Field

[0001] The present invention relates to a method for creating a tire model.

Background Art

[0002] When analyzing the behavior and grounding state of a tire, if a numerical analysis model is created from the design drawing of the tire and the behavior and grounding state are analyzed, the results may differ from those of the actual tire. One of the reasons for this is that the cross-sectional shape and internal structure of the actual tire are different from those of the design drawing. Factors that cause variations in the cross-sectional shape and internal structure include variations in members, rubber flow during vulcanization, and thermal shrinkage during the post-cure inflation (PCI) process after vulcanization. Patent Documents 1 and 2 describe methods for reflecting the shape of an actual tire when creating a numerical analysis model.

[0003] For example, Patent Document 1 describes a method for creating a tire model that includes a step of measuring the tire shape and superimposing cross-sectional data of the internal structure of the initial tire by synthesizing tire radial cross-sectional data obtained by using numerical values of data measured from a design drawing or a tire cross-sectional photograph inside the cross-sectional data of the outer shape of the measured actual tire.

[0004] Patent Document 2 describes a method for creating a tire model that includes a step of measuring the outer contour shape of a tire cross-section and deforming a base model so that the reference points of the geometrically modeled base model corresponding to the same parts as the reference points of the measured contour shape coincide.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in both of the tire model creation methods described in Patent Documents 1 and 2, there is room for improvement in terms of creating a more accurate numerical analysis model that reflects the shape of an actual tire. [Means for solving the problem]

[0007] The tire model creation method according to the present invention is a tire model creation method that includes: a cross-sectional data acquisition step of photographing a cross-section of an actual tire corresponding to the tire to be analyzed and acquiring cross-sectional data including the cross-sectional contour from the photographed image of the cross-section; a modification step of modifying the design drawing of the tire to be analyzed so as to match the acquired cross-sectional contour; and an analysis model creation step of creating a numerical analysis model of the tire to be analyzed based on the modified design drawing, wherein the modification step matches either the outer shape or the inner shape of the acquired cross-sectional contour with the corresponding contour shape of the design drawing, modifies the thickness of the rubber member in the design drawing according to the difference between the thickness of the contour shape in the design drawing and the measured thickness of the cross-sectional contour, and matches the other shape of the cross-sectional contour with the corresponding contour shape of the design drawing, thereby reflecting the cross-sectional contour of the actual tire in the design drawing. [Effects of the Invention]

[0008] According to the tire model creation method of the present invention, the difference between a photographic image of the cross-section of an actual tire and the design drawing of the tire to be analyzed before modification can be reflected in the thickness of the rubber material, which is the internal structure of the design drawing of the tire to be analyzed. Therefore, a more accurate numerical analysis model of the tire to be analyzed that reflects the shape of the actual tire can be created. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view from a design drawing of an example of a pneumatic tire, which is the tire being analyzed, with the groove shape omitted. [Figure 2]This figure shows a tire model creation system used in the tire model creation method of the embodiment. [Figure 3] This is a flowchart showing a method for creating a tire model as an example of an embodiment. [Figure 4] Figure 3 is a flowchart showing the process of acquiring CT images, which are tire cross-section images, and tire cross-section data. [Figure 5] This figure shows the feature lines of tire cross-sectional data obtained from CT images of actual tires corresponding to the tire shown in Figure 1. [Figure 6] Figure 3 is a flowchart showing the tire design drawing modification process and the tire numerical analysis model creation process. [Figure 7A] This diagram shows how to modify the tread portion of the first revised design drawing based on the differences between the design drawing and the tire cross-section data. [Figure 7B] This diagram shows how to modify the tread portion in the second revised design drawing based on the differences between the first revised drawing and the tire cross-section data. [Figure 8] This diagram shows how to modify the portion including the sidewall in the first and second revised design drawings, based on the differences between the design drawings and the tire cross-section data. [Figure 9A] This diagram shows how to correct the part including the chainring in the first revised drawing of the design drawing, based on the differences between the design drawing and the tire cross-section data. [Figure 9B] This diagram shows how to modify the part including the chainring in the second revised design drawing based on the differences between the first revised drawing and the tire cross-section data. [Figure 10] This figure shows the tire cross-section in the second modified figure, which has been modified according to the method of the embodiment shown in Figure 1. [Modes for carrying out the invention]

[0010] Hereinafter, an example of an embodiment of the tire model creation method according to the present invention will be described in detail with reference to the drawings. The embodiment described below is merely an example, and the present invention is not limited to the following embodiments.

[0011] The tire model creation method of this embodiment is a method for creating a numerical analysis model of a tire used for performing analyses such as ground contact analysis and behavior analysis of a pneumatic tire used for an automobile or the like.

[0012] [Configuration of Tire] First, the configuration of the pneumatic tire 10 will be described using FIG. 1. FIG. 1 is a meridian cross-sectional view of an example of the pneumatic tire 10 that is the analysis target tire, and is a cross-sectional view in the design drawing shown with the groove shape omitted. FIG. 1 is a pre-modification drawing before reflecting the tire cross-sectional data obtained from photographing an actual tire. Hereinafter, the pneumatic tire 10 will be referred to as the tire 10. In FIG. 1, the hatching indicating the cross-section is omitted. Also, hereinafter, the tire axial direction may be indicated by X and the tire radial direction may be indicated by Y.

[0013] The tire 10 has a pair of beads 12 provided on both sides in the tire axial direction X, a carcass 19 spanned between the pair of beads 12, a belt layer 15 wound around the outer peripheral side of the middle part of the carcass 19, and a rubber tread 16 provided on the outer side in the tire radial direction Y of the belt layer 15. The belt layer 15 is arranged such that the inner belt 15b overlaps the inner peripheral side of the outer belt 15a and reinforces the tread 16. Each of the belts 15a and 15b is formed by covering a plurality of metal cords arranged in a direction inclined with respect to the tire circumferential direction with rubber. In adjacent belts 15a and 15b, the cords are inclined in opposite directions with respect to the tire circumferential direction so that the cords of each other cross.

[0014] A rubber sidewall 18 is continuous on the outer side in the tire axial direction X of the tread 16. The tire 10 is filled with air in a state where a rim (not shown) is assembled on the inner peripheral side.

[0015] The bead 12 has a bead core 13 and a bead filler 14 extending radially outward in the tire radial direction Y of the bead core 13.

[0016] The bead core 13 is an annular member in which a rubber-coated metal bead wire is wound a plurality of times in the tire circumferential direction. The bead core 13 serves to fix the air-filled tire 10 to the rim. The bead filler 14 is made of rubber and is provided to increase the rigidity of the bead 12.

[0017] The carcass 19 is composed of a plurality of sheet-like members formed by covering a large number of cords made of organic fibers with rubber.

[0018] On the outer side of the carcass 19 in the tire axial direction and on the inner side of the sidewall 18 in the tire radial direction, a rubber chafer 63 is provided. The chafer 63 extends to a position radially inside the bead core 13 and reaches the inner surface of the tire.

[0019] An inner liner 61 made of rubber is provided on the entire inner surface of the tire 10. The inner end of the inner liner 61 in the tire radial direction Y is continuous with the chafer 63.

[0020] Since the tire 10 is configured as described above, for example, along the tire radial line indicated by the straight line A1 in FIG. 1, the tread 16, the outer belt 15a, the inner belt 15b, the carcass 19, and the inner liner 61 are arranged in order from the outside in the tire radial direction. Also, along the tire axial line near the center in the tire radial direction indicated by the straight line A2 in FIG. 1, the sidewall 18, the carcass 19, and the inner liner 61 are arranged in order from the outside in the tire axial direction. Further, along the tire axial line near the inner end in the tire radial direction indicated by the straight line A3 in FIG. 1, the chafer 63, the carcass 19, the bead core 13 of the bead 12, the carcass 19, and the inner liner 61 are arranged in order from the outside in the tire axial direction.

[0021] Next, a method for creating a numerical analysis model of the tire 10 to be analyzed will be described. According to the tire model creation method of the embodiment, when analyzing the behavior and grounding state of an actual tire, a more accurate numerical analysis model of the tire 10 that reflects the shape of the actual tire and can obtain results closer to the analysis results of the actual tire can be created.

[0022] [Tire Model Creation System] Figure 2 shows a tire model creation system 1 used in the tire model creation method of the embodiment. The tire model creation system 1 consists of a design support device 20 and a simulation device 70.

[0023] The design support device 20 is a CAD system consisting of a computer equipped with a control device 50 including a processor and memory. The design support device 20 may be connected to a drawing data management server that manages designed drawing data via a network such as a LAN.

[0024] The design support device 20 includes an input device 22, a display device 30, a storage unit 40, and a control device 50. The input device 22 is used by the user to input instructions, etc., and consists of a keyboard, mouse, touch panel, etc.

[0025] The display device 30 is a display that shows images of input information obtained using the input device 22, output images such as design drawings, captured images, and cross-sectional contours represented by cross-sectional data acquired from captured images, and is composed of, for example, a liquid crystal display, an organic EL display, etc.

[0026] The memory unit 40 stores programs that run on the control device 50, such as design support programs, and data necessary for designing and modifying CAD drawings. The memory unit 40 may be configured as an external storage device.

[0027] The control device 50 includes a data acquisition unit 51, a design modification support unit 52, and a CT image acquisition unit 53. The data acquisition unit 51 acquires data such as already created design drawings from the storage unit 40, a data management server connected to the design support device 20, or an external storage medium such as a USB memory.

[0028] The design modification support unit 52 enables design and modification work by allowing users to perform drawing, editing, and other functions through command selection, similar to a standard CAD system.

[0029] The CT image acquisition unit 53 acquires tire cross-sectional data, which is a cross-sectional image of the width direction, which is a meridian cross-section along the width direction of the actual tire, as captured by the X-ray CT scanner, as described later. The "actual tire" is manufactured based on the design drawing of the tire 10 before the modifications described later are made. The control device 50 is configured to display the captured image of the acquired tire cross-sectional data on the display device 30 simultaneously with the design drawing on the screen where the design modification work is performed. Furthermore, the control device 50 can automatically or manually create feature lines as contour lines of the outer shape of the actual tire in the cross-sectional image, as well as contour lines of internal structures such as the belts 15a, 15b and the bead core 13, by performing image processing on the captured image displayed on the display device 30. Feature lines are created, for example, by performing noise reduction and filtering based on brightness values ​​on the cross-sectional image, then binarizing the filtered image to detect edges, and acquiring a binary image containing the edges, thereby creating each contour line of the cross-sectional image. At this time, the system may be configured to allow the user to manually select and delete unnecessary contour lines other than the feature lines.

[0030] The design modification support unit 52 described above may be configured to have a function that measures the length between two points, for example, the thickness of the cross-sectional contour, by specifying two points on the cross-sectional contour in the cross-sectional image including the feature lines described above. Similarly, the design drawing may also be configured to have a function that measures the length between two points, for example, the thickness of the contour shape, by specifying two points on the contour shape corresponding to the cross-sectional contour.

[0031] Next, the simulation device 70 consists of a computer equipped with a control device including a processor and memory, and performs analyses such as the behavior analysis of the tire 10. The simulation device 70 may consist of one computer or multiple computers. In addition, some of the functions of the simulation device may reside on a server or the like connected via a communication network.

[0032] The simulation device 70, like the design support device 20, includes an input device, a display device, a storage unit, and a control unit. The simulation device 70 is connected to the design support device 20 via a network such as a LAN, enabling the acquisition of data such as design drawings and revised design drawings. The simulation device 70 is not connected to the design support device 20, and the user can also use an external storage medium such as a USB memory stick to have the simulation device 70 acquire data such as design drawings and revised design drawings obtained from the design support device 20. The user can input analysis conditions, numerical analysis model creation conditions, etc., into the control unit using the input device. The display device is a display that shows images of input information using the input device, output images such as analysis results, etc. The storage unit stores programs that run on the control unit and data necessary for model generation for analysis.

[0033] The control device of the simulation device 70 includes a tire model creation unit 71 that creates an FEM (Finite Element Method) model, which is a numerical analysis model of the tire 10; a road surface model creation unit 72 that creates a road surface model; a condition setting unit 73 that sets conditions such as boundary conditions for performing the analysis; and an analysis unit 74 that performs analyses such as behavior analysis and contact analysis.

[0034] [How to create a tire model] Next, a tire model creation method for creating a numerical analysis model using the tire model creation system 1 will be described. Figure 3 is a flowchart of a tire model creation method for one embodiment. In S10 of Figure 3, the tire design drawing creation process is performed using the design support device 20 described above to create a design drawing of the tire 10 to be analyzed. Next, the design support device 20 takes a CT image, which is a photograph of the cross-section of an actual tire corresponding to the tire 10, that is, an actual tire manufactured based on the design drawing of the tire 10 before the modifications described later, and performs a CT image and cross-sectional data acquisition process (S20) to acquire cross-sectional data including the cross-sectional contour and internal structure of the tire cross-section from the CT image.

[0035] Figure 4 is a flowchart showing the process for acquiring CT images and cross-sectional data in Figure 3. In this acquisition process, at S21 in Figure 4, first, a real tire is set up to acquire a CT image. Next, at S22, an X-ray CT scanner is used to photograph the external shape and internal structure of the tire's cross-section in the width direction. At this time, the actual tire is set up differently depending on whether it is in a standalone state without a rim or in a state with a rim attached and filled with a small amount of internal pressure. For example, in the standalone state, to minimize the effect of deflection due to gravity on the actual tire, the tire is supported upright, and a CT image is taken at a horizontal position near the vertical center of the actual tire. In the case of a tire with a rim attached, the rim is assembled at room temperature, and the internal pressure of the actual tire is kept sufficiently low so that deformation due to internal pressure is minimized when the tire is set up and a CT image is taken.

[0036] Next, in S24, the design support device 20 acquires tire cross-sectional data from the captured images acquired in S22, including the cross-sectional contour of the outer shape of the actual tire's cross-section and the cross-sectional contour of the metal members of the internal structure. This allows the system to acquire the outer shape of the cross-section of the actual tire and the positions of the metal members of the internal structure, such as the belt layer 15 and the bead core 13.

[0037] Figure 5 shows an example of feature lines of tire cross-sectional data obtained from a CT image of a real tire 10a corresponding to the tire 10 shown in Figure 1. The result of the feature lines shown in Figure 5 also shows that the outline shape of the cross-section of the real tire 10a and the positions of the internal structure, namely the belt layer 15 and the bead core 13, can be obtained using the method in this example.

[0038] Next, in S30 of Figure 3, a tire design drawing modification process is performed to modify the design drawing of the tire 10 to be analyzed so that it matches the cross-sectional contour of the tire cross-section obtained. Then, in S40, an analysis model creation process is performed to create a numerical analysis model of the tire 10 based on the modified design drawing.

[0039] Figure 6 is a flowchart showing the tire design drawing modification process (S30) and the analysis model creation process (S40) in Figure 3. The tire design drawing modification process includes steps S31 to S33 in Figure 6. Specifically, in S31, the position of the tire 10 within the design drawing is changed overall so that the shape of the outer surface contour of the tire 10 in the design drawing matches the outer surface shape of the cross-sectional contour of the actual tire 10a (Figure 5) obtained from the CT image. At this time, the thickness of the tire 10 remains the same as in the original design drawing.

[0040] Next, in S32, the thickness of the tire 10 in the design drawing and the cross-sectional contour of the actual tire 10a (Figure 5) are made to match overall. Specifically, depending on the difference between the thickness of the contour shape of the tire 10 in the design drawing and the measured thickness of the cross-sectional contour of the actual tire 10a, the thickness of the rubber material inside the tire 10 in the design drawing is modified so that the inner contour of the tire 10 in the design drawing matches the inner shape of the cross-sectional contour of the actual tire 10a, thereby reflecting the cross-sectional contour of the actual tire 10a in the design drawing. At this time, the rubber material to be modified is the outermost and thickest rubber material at each position where the tire thickness is to be modified. For example, if the thickness along the tire radial direction in the part including the tread 16 is to be modified, for example, if the thickness along the tire radial line A1 shown in Figure 1 is to be modified, the materials laminated along the tire radial line A1 are the tread rubber, belt layer 15, carcass 19, and inner liner 61 that make up the tread 16. Here, we can consider that only the tread rubber, which is positioned on the outermost side and in contact with the mold, experiences the greatest temperature rise and has the greatest thickness, exhibits thickness fluctuations. In other words, other components besides the tread rubber, such as the belt layer 15 which is mainly composed of metal, the carcass 19 which is mainly composed of fiber, and the inner liner 61 which has a small thickness, are considered to have no thickness fluctuations. Therefore, the difference in thickness between the tire 10 in the design drawing and the actual tire 10a is resolved by correcting the thickness of the tread rubber. The tread rubber corresponds to the outer rubber component.

[0041] Furthermore, if the thickness of the sidewall 18 along the tire axis, passing near the center of the tire's radial direction, is to be modified, for example, if the thickness along the tire axis line A2 shown in Figure 1 is to be modified, the components laminated along the tire axis line A2 are the sidewall rubber, carcass 19, and inner liner 61 that constitute the sidewall 18. Here, it can be assumed that only the sidewall rubber, which is positioned on the outermost side and in contact with the mold, experiences the greatest temperature rise and has the greatest thickness, has a variation in thickness. In other words, components other than the sidewall rubber, such as the carcass 19, which is mainly composed of fiber, and the inner liner 61, which has a small thickness, are considered to have no variation in thickness. Therefore, the difference in thickness between the tire 10 in the design drawing and the actual tire 10a is resolved by modifying the thickness of the sidewall rubber. The sidewall rubber also corresponds to the outer rubber component.

[0042] Furthermore, if the thickness along the tire axis passing through the bead core 13 is to be modified, for example, if the thickness along the tire axis line A3 is to be modified, the components laminated along the tire axis line A3 shown in Figure 1 are the cheese rubber constituting the cheese 63, the carcass 19, the bead core 13, and the inner liner 61. Here, it can be considered that only the cheese rubber, which is positioned on the outermost side and in contact with the mold, experiences the greatest temperature rise and has the largest thickness, has a variation in thickness. In other words, components other than the cheese rubber, such as the bead core 13 which is mainly composed of metal, the carcass 19 which is mainly composed of fiber material, and the inner liner 61 which has a small thickness, are considered to have no variation in thickness. Therefore, the difference in thickness between the tire 10 in the design drawing and the actual tire 10a is resolved by modifying the thickness of the cheese rubber. The cheese rubber also corresponds to the outer rubber component.

[0043] Furthermore, if the thickness along the tire axis passing through the bead filler 14 is the one to be modified, the bead filler 14 is harder than the surrounding rubber, so it can be considered that there is no change in thickness.

[0044] The above explains how to correct the thickness of the tire 10 in the design drawing at three locations by correcting the thickness of the outermost and thickest rubber component, thereby matching the thickness of the tire 10 in the design drawing with the actual tire 10a. On the other hand, when correcting the thickness of other parts of the tire 10, the thickness of the outermost rubber component may also be corrected to match the thickness of the tire 10 in the design drawing with the actual tire 10a. For example, in the part where the tread rubber and sidewall rubber overlap in the thickness direction, the thickness of the tread rubber can be corrected as the outermost component. In this case, since the outermost component is in contact with the mold, it is thought that the amount of thickness change will be large due to the large temperature rise.

[0045] Using the method described above, the tire thickness is corrected by modifying the thickness of the rubber material in the cross-sectional contour shape of the tire 10 in the design drawing so that it matches the thickness of the actual tire 10a overall. In addition, in the cross-sectional contour shape of the tire 10 in the design drawing, the inner position of the contour shape is modified at multiple circumferential positions along the outer surface in accordance with the correction of the tire thickness, and for the parts of the thickness that have not been corrected, the thickness and contour shape may be corrected using the positions where the thickness has been corrected by smoothing processing in CAD.

[0046] By modifying the thickness of the rubber component in this way, the shape of the tire 10 in the design drawing will reflect the shape of the actual tire 10a. This allows the difference between the photographic image of the cross-section of the actual tire 10a and the design drawing of tire 10 before modification to be reflected in the thickness of the rubber component, which is the internal structure of the tire 10 design drawing. As a result, a more accurate numerical analysis model of tire 10 that reflects the shape of the actual tire 10a can be created.

[0047] In this process, during the tire design drawing modification, the thickness of the outermost rubber member located within the cross-section of the design drawing is modified according to the difference between the thickness of the contour shape of the tire 10 design drawing and the measured thickness of the cross-sectional contour of the actual tire 10a, thereby reflecting the cross-sectional contour of the actual tire 10a in the design drawing.

[0048] Next, in step S33 of Figure 6, the position of the internal structure of the actual tire 10a is reflected in the tire 10 in the design drawing. Specifically, the belt layer 15 and the bead core 13 are metal members that serve as reinforcing members, and their positions inside the tire can be obtained from tire cross-sectional data obtained from captured images. Therefore, based on this position, the thickness of the surrounding members is modified so that the positions of the metal members match between the design drawing and the internal structure of the cross-section of the actual tire 10a. More specifically, after the step of changing the thickness of the outer rubber member described above, the thickness of the inner rubber member, which is the next thickest after the outer rubber member and softer than a predetermined hardness, and the thickness of the outer rubber member are modified according to the difference in position between the internal structure of the design drawing and the internal structure of the cross-section of the actual tire. The inner rubber member is, for example, the inner liner 61.

[0049] Furthermore, in the tire design drawing modification process, the thickness of the outer rubber member and the inner rubber member within the cross-section of the design drawing is increased or decreased so as not to change the overall thickness of the cross-section, thereby matching the positions of the belt layer 15 and the bead core 13 within the design drawing to the internal structure of the cross-section of the actual tire. This allows the position of the internal structure obtained from the captured image of the actual tire 10a to be reflected in the thickness of the rubber material, which is the internal structure of the tire design drawing 10, making it possible to create a more accurate numerical analysis model of tire 10 that reflects the shape of the actual tire 10a.

[0050] Next, in S40 of Figure 3 and S40 of Figure 6, the simulation device 70 performs an analysis model creation process to create a numerical analysis model of the tire 10 based on the revised design drawings. Then, in S50 of Figure 3, the simulation device 70 performs a road surface model creation process to create a road surface model, and after setting the analysis conditions, it performs an analysis execution process such as behavioral analysis using the numerical analysis model (S60).

[0051] Next, using Figures 7A to 9B, we will explain in more detail the methods for modifying the thickness of the tread 16, the sidewall 18, and the chaff 63 during the tire design drawing modification process.

[0052] Figure 7A shows how to correct the thickness of the portion including the tread 16 in the first revised drawing of the design drawing, based on the difference between the design drawing and the tire cross-sectional data. Figure 7A shows the stacking state of multiple members in the portion including the tread, for example, in the cross-section along the tire radial line A1 in Figure 1, in the design drawing, the tire cross-sectional data obtained from the CT image (CT image cross-section), and the first revised drawing. The first revised drawing is corrected according to the difference in thickness between the design drawing and the tire cross-sectional data. In Figure 7A, the tire thickness T2 in the tire cross-sectional data is smaller than the tire thickness T1 in the design drawing. Therefore, as in the first revised drawing, the thickness of the tread rubber, which is the outermost rubber member located in the cross-section of the design drawing, is corrected to be smaller by the difference between the tire thickness T1 in the design drawing and the tire thickness T2 in the tire cross-sectional data, so that the tire thickness T3 in the first revised drawing matches the tire thickness T2 at the corresponding position in the tire cross-sectional data (T3=T2).

[0053] On the other hand, if the tire thickness T2 in the tire cross-section data is greater than the tire thickness T1 in the design drawing, then in the portion where the thickness is greater, the tread rubber thickness in the cross-section of the design drawing is increased by the difference between the tire thickness T1 in the design drawing and the tire thickness T2 in the tire cross-section data in the first revised drawing, so that the tire thickness T3 in the first revised drawing matches the tire thickness T2 at the corresponding position in the tire cross-section data.

[0054] On the other hand, the outer surface position of the outer belt 15a and the inner surface position of the inner belt 15b differ between the first revised drawing in Figure 7A and the tire cross-sectional data. When the belt positions differ between the first revised drawing and the tire cross-sectional data in this way, the thickness of the components whose thickness was not changed in the process shown in Figure 7A is corrected.

[0055] Figure 7B shows how to correct the thickness of the portion including the tread 16 in the second revised drawing of the design drawing, based on the difference between the first revised drawing and the tire cross-section data. The second revised drawing is obtained by modifying the first revised drawing according to the difference in the position of the internal structure between the first revised drawing and the tire cross-section data. The other meanings represented by Figure 7B are the same as in the case of Figure 7A. In the modification in Figure 7B, the thickness of the tread rubber and the thickness of the inner liner 61 are modified so that the overall thickness in the radial direction of the tire in the portion including the tread 16 does not change, thereby making the outer surface position of the outer belt 15a and the inner surface position of the inner belt 15b match between the second revised drawing and the tire cross-section data. At this time, if the boundary position between the outer belt 15a and the inner belt 15b differs between the second revised drawing and the tire cross-section data, the boundary position can be matched by modifying the thickness of the rubber covering each belt 15a and 15b.

[0056] Figure 8 shows how to correct the thickness of the portion including the sidewall 18 in the first and second revised drawings of the design drawing, based on the difference between the design drawing and the tire cross-section data. Figure 8 shows the stacking state of multiple members in the portion including the sidewall 18, for example, in the cross-section along the tire axial line A2 in Figure 1, in the design drawing, the tire cross-section data obtained from the CT image (CT image cross-section), and the first and second revised drawings, respectively. The first revised drawing is corrected according to the difference in thickness between the design drawing and the tire cross-section data. In Figure 8, the tire thickness T5 in the tire cross-section data is smaller than the tire thickness T4 in the design drawing. Therefore, as in the first revised drawing, the thickness of the sidewall rubber, which is the outermost rubber member located in the cross-section of the design drawing, is corrected to be smaller by the difference between the tire thickness T4 in the design drawing and the tire thickness T5 in the tire cross-section data, so that the tire thickness T6 in the first revised drawing matches the tire thickness T5 at the corresponding position in the tire cross-section data (T6=T5).

[0057] On the other hand, if the tire thickness T5 in the tire cross-section data is greater than the tire thickness T4 in the design drawing, then in the portion where the thickness is greater, the first revised drawing is modified to increase the thickness of the sidewall rubber within the cross-section of the design drawing by the difference between the tire thickness T1 in the design drawing and the tire thickness T2 in the tire cross-section data, so that the tire thickness T6 in the first revised drawing matches the tire thickness T5 at the corresponding position in the tire cross-section data.

[0058] Figure 9A shows how to correct the thickness of the portion including the Chehar 63 in the first revised drawing of the design drawing, based on the difference between the design drawing and the tire cross-section data. Figure 9A shows the stacking state of multiple members in the portion including the Chehar 63, for example, in the cross-section along the tire axial line A3 in Figure 1, in the design drawing, the tire cross-section data obtained from the CT image (CT image cross-section), and the first revised drawing. The first revised drawing is corrected according to the difference in thickness between the design drawing and the tire cross-section data. In Figure 9A, the tire thickness T8 in the tire cross-section data is smaller than the tire thickness T7 in the design drawing. Therefore, as in the first revised drawing, the thickness of the Chehar rubber, which is the outermost rubber member located in the cross-section of the design drawing, is corrected to be smaller by the difference between the tire thickness T7 in the design drawing and the tire thickness T8 in the tire cross-section data, so that the tire thickness T9 in the first revised drawing matches the tire thickness T8 at the corresponding position in the tire cross-section data (T9=T8).

[0059] On the other hand, if the tire thickness T8 in the tire cross-section data is greater than the tire thickness T7 in the design drawing, then in the portion where it is greater, the thickness of the chaff rubber within the cross-section of the design drawing is increased by the difference between the tire thickness T7 in the design drawing and the tire thickness T8 in the tire cross-section data in the first revised drawing, so that the tire thickness T9 in the first revised drawing matches the tire thickness T8 at the corresponding position in the tire cross-section data.

[0060] On the other hand, the outer and inner positions of the bead core 13 of the bead 12 differ between the first revised drawing in Figure 9A and the tire cross-sectional data. When the position of the bead core 13 differs between the first revised drawing and the tire cross-sectional data in this way, it is possible that the movement of the material surrounding the bead core 13 or the expansion and contraction of the carcass 19 have an effect. As a result, the thickness of the material whose thickness was not changed in the process shown in Figure 9A is changed.

[0061] Figure 9B shows how to correct the thickness of the part including the chaff 63 in the second revised drawing of the design drawing, based on the difference between the first revised drawing and the tire cross-section data. The second revised drawing is obtained by modifying the first revised drawing according to the difference in the position of the internal structure between the first revised drawing and the tire cross-section data. The other meanings represented by Figure 9B are the same as in the case of Figure 9A. In the modification in Figure 9B, the thickness of the chaff rubber and the thickness of the inner liner 61 are modified so that the overall thickness in the tire axial direction in the part including the chaff 63 does not change, thereby matching the outer and inner positions of the bead core 13 in the second revised drawing and the tire cross-section data. By using the tire model creation method including the process shown in Figures 7A to 9B, it is possible to create a numerical analysis model of the tire 10 that reflects the shape of the actual tire 10a and has even higher accuracy.

[0062] In Figures 9A and 9B, the case where only the carcass 19 and inner liner 61 are positioned on the inner surface side of the bead core 13 is explained. However, there are also cases where the chafer wraps around to the inner surface side of the bead core 13 and is positioned between the carcass and the inner liner. In this case, however, the thickness of the chafer positioned on the inner surface becomes considerably smaller, so the change in thickness in that area can be ignored.

[0063] Furthermore, the above describes a case in which, in the tire design drawing modification process, the outer surface shape of the acquired cross-sectional contour of the actual tire 10a is matched with the corresponding outer surface contour shape of the design drawing, and the thickness of the rubber material in the design drawing is modified according to the difference between the thickness of the contour shape in the design drawing and the thickness of the measured cross-sectional contour, thereby matching the corresponding inner surface contour shape of the design drawing with the inner surface shape of the cross-sectional contour, and thereby reflecting the cross-sectional contour of the actual tire 10a in the design drawing.

[0064] Alternatively, in the tire design drawing modification process, the inner surface shape of the acquired cross-sectional contour of the actual tire 10a may be matched with the corresponding inner surface contour shape of the design drawing, and the thickness of the rubber material in the design drawing may be modified according to the difference between the thickness of the contour shape in the design drawing and the thickness of the measured cross-sectional contour, thereby matching the corresponding outer surface contour shape of the design drawing with the outer surface shape of the cross-sectional contour, and thus the cross-sectional contour of the actual tire 10a may be reflected in the design drawing.

[0065] Figure 10 shows the tire cross-section in the second modified drawing, which is modified from the design drawing in Figure 1 using the method of the embodiment. The tire cross-sectional shape in Figure 10 is obtained by modifying the tire cross-sectional shape of the design drawing in Figure 1 using the method of the embodiment, with respect to the cross-sectional data obtained from the CT image of the corresponding actual tire 10a shown in Figure 5. Note that in Figures 1 and 10, the groove shape of the tread 16 is omitted for simplification. However, when actually creating a numerical analysis model, as shown in Figure 10, the groove depth can be modified from the design shape according to the difference in thickness at each part of the tread between the design drawing and the cross-sectional data, and then the grooves from the design drawing can be combined with the shape of the tire cross-section in the second modified drawing. It is preferable to create the numerical analysis model based on this combined groove shape in order to improve the accuracy of the analysis.

[0066] The inventor created a numerical analysis model (example model) of tire 10 based on a revised drawing obtained by modifying the design drawing using cross-sectional data obtained from a CT image of an actual tire 10a. The results of the ground contact analysis performed using this numerical analysis model were compared with the results of the ground contact analysis performed using a numerical analysis model (comparative example model) created based on the design drawing without reflecting information from the actual tire 10a. Specifically, the measured results of the ground contact width, ground contact length of the center and shoulder areas, and (shoulder ground contact length) / (center ground contact length) of the ground contact shape on the tread, performed using the actual tire 10a, were compared with the ground contact analysis results for the lengths or ratios corresponding to each measured item, performed using the example model and the comparative example model. As a result, the difference between the ground contact analysis performed using the comparative example model and the measured results increased from -9.9% to +6.1%, while the difference between the ground contact analysis performed using the example model and the measured results decreased from -4.0% to +2.7%. This confirmed the effectiveness of the embodiment.

[0067] Furthermore, while the above describes creating a numerical analysis model based on the shape after modifications made using the first revised design drawing and then the second revised drawing, it is also possible to create a numerical analysis model based on the shape after modifications using the first revised drawing but without modifications using the second revised drawing. [Explanation of symbols]

[0068] 10 Pneumatic tire (tire), 10a Actual tire, 12 Bead, 13 Bead core, 14 Bead filler, 15 Belt layer, 15a Outer belt, 15b Inner belt, 16 Tread, 17 Sidewall, 18 Sidewall, 19 Carcass, 20 Simulation device, 22 Input device, 30 Display device, 40 Storage unit, 50 Control device, 51 Data acquisition unit, 52 Design modification support unit, 53 CT image acquisition unit, 61 Inner liner, 63 Chester, 70 Simulation device, 71 Tire model creation unit, 72 Road surface model creation unit, 73 Condition setting unit, 74 Analysis unit.

Claims

1. A cross-sectional data acquisition step involves taking a photograph of the cross-section of an actual tire corresponding to the tire to be analyzed, and obtaining cross-sectional data including the cross-sectional contour from the photographed image of the cross-section, A modification step of modifying the design drawing of the tire to be analyzed so as to match the acquired cross-sectional contour, A tire model creation method comprising: an analysis model creation step of creating a numerical analysis model of the tire to be analyzed based on the revised design drawings; The modification step involves matching either the outer or inner shape of the acquired cross-sectional contour with the corresponding contour shape in the design drawing, and adjusting the thickness of the rubber member in the design drawing according to the difference between the thickness of the contour shape in the design drawing and the measured thickness of the cross-sectional contour, thereby matching the corresponding contour shape in the design drawing with the other shape of the cross-sectional contour, and thereby reflecting the cross-sectional contour of the actual tire in the design drawing. How to create a tire model.

2. The cross-sectional data acquisition step involves acquiring the cross-sectional data, including the cross-sectional contour and internal structure, from the captured image of the cross-section of the actual tire. The modification step involves modifying the thickness of the outermost rubber member located within the cross-section of the design drawing, according to the difference between the thickness of the contour shape in the design drawing and the measured thickness of the cross-sectional contour, thereby reflecting the cross-sectional contour of the actual tire in the design drawing. Following this, the thickness of the inner rubber member, which is the next thickest and softer than a predetermined hardness, and the thickness of the outer rubber member are modified according to the difference in position between the internal structure in the design drawing and the internal structure in the cross-sectional data. The method for creating a tire model according to claim 1.

3. The modification step involves increasing or decreasing the thickness of the outer rubber member and the inner rubber member within the cross-section of the design drawing so that the overall thickness of the cross-section does not change, thereby aligning the positions of the belt and bead in the design drawing with the internal structure of the cross-sectional data. The method for creating a tire model according to claim 2.

4. In the cross-sectional data acquisition step, an X-ray CT device is used to acquire the cross-sectional data of the tire to be analyzed, either with the rim attached and filled with minute internal pressure, or without the rim attached. A method for creating a tire model according to any one of claims 1 to 3.

Images