Method for observing the contact surface of rubber elastic bodies

Abstract

To allow a large number of marks to be provided on a surface of a rubber elastic body in an effortless and simple manner.SOLUTION: A method of observing a tread of a rubber elastic body 1 according to the present invention comprises a mark forming step of forming marks 6 on a tread 2 of the rubber elastic body 1 and an image capturing step of capturing an image of the tread 2 while the rubber elastic body 1 with the formed marks 6 is sitting on a road surface using an image capturing device 13. The mark forming step comprises a cut forming step of forming parallelly arranged multiple cuts 4 and an injection step of injecting paint 5 into the multiple cuts 4.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for observing the contact surface of a rubber elastic body. [Background technology]

[0002] To analyze the deformation of the rubber elastomer that constitutes the contact surface of a tire, one method is to place multiple marks on the surface of the rubber elastomer, photograph the surface of the rubber elastomer along with the multiple marks while applying shear deformation to the rubber elastomer, and analyze the image of the rubber elastomer that includes the multiple marks to observe the contact surface of the rubber elastomer.

[0003] In such a method, if a mark is formed by applying paint directly to the surface of the rubber elastomer, the paint on the mark may peel off when the rubber elastomer is subjected to shear deformation, making it impossible to accurately observe the contact surface. Furthermore, because paint applied directly to the surface of the rubber elastomer has a different coefficient of friction from that of the rubber elastomer, it is difficult to meet the demands for precise observation, such as when analyzing deformation on surfaces with a low coefficient of friction, such as ice surfaces.

[0004] Therefore, Patent Document 1 discloses a technique for forming marks on the tire surface by injecting a colored material into holes formed on the tire surface by laser processing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-1628 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, a large number of holes must be formed by laser processing, which is a time-consuming process. Therefore, an object of the present invention is to provide a method for observing the contact surface of a rubber elastic body that can easily form a large number of markers on the surface of a rubber elastic body without requiring much time and effort. [Means for solving the problem]

[0007] The method for observing the contact surface of a rubber elastic body of this embodiment includes a marking formation process for forming marks on the contact surface of the rubber elastic body, and an imaging process for imaging the contact surface of the rubber elastic body with the marks formed thereon, where the rubber elastic body is in contact with the road surface, using a camera, and the marking formation process includes a slit formation process for forming multiple slits arranged parallel to each other, and an injection process for injecting paint into the multiple slits. [Effects of the Invention]

[0008] In the present invention, by providing the above-mentioned features, it is possible to easily provide a large number of marks on the surface of the rubber elastic body. [Brief explanation of the drawings]

[0009] [Figure 1] Flow diagram showing a method for observing the contact surface of a rubber elastic body [Figure 2] A plan view of a rubber elastic body on which a plurality of marks are formed. [Figure 3] Cross section AA of Figure 2 [Figure 4] FIG. 10 is a perspective view illustrating a step of forming a slit. [Figure 5] (a) to (e) are cross-sectional views explaining the injection process. [Figure 6] Schematic diagram showing an example of an apparatus used to observe the contact surface of a rubber elastic body. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] This embodiment shows an example in which strain occurring in a contact patch 2 where a rubber elastic body 1 comes into contact with a test road surface 11 is measured.

[0012] As illustrated in Figure 1, the method of this embodiment includes a step of producing a rubber elastomer 1 (step S1), a slit formation step (step S2) of forming multiple slits 4 on the contact surface 2 of the rubber elastomer 1, an injection step (step S3) of injecting paint 5 into the multiple slits 4 to form multiple marks 6, and a measurement step (step S4) of using the rubber elastomer 1 with the multiple marks 6 formed as a test piece to measure the strain occurring on the contact surface 2 using a measuring device 10.

[0013] (1) Process for producing rubber elastic body 1 The rubber elastic body 1 is produced by molding vulcanized rubber into a predetermined shape. In this embodiment, as shown in FIG. 6, the rubber elastic body 1 has a rectangular parallelepiped shape, and the contact surface 2 that is pressed against the test road surface 11 of the measuring device 10 has a rectangular shape. The contact surface 2 may be provided with sipes 3, each consisting of a long, narrow groove with a groove width of 1.5 mm or less and a depth of 2 mm to 10 mm, as shown in FIGS. 2 and 3. In this embodiment, the sipes 3 are provided so as to penetrate the periphery of the rubber elastic body 1, but this is not restrictive. Furthermore, the sipes 3 have a cross-sectional shape that includes a wave-shaped portion and a straight portion, but may also be entirely straight.

[0014] (2) Cutting process In the slit forming step, a plurality of narrow groove-like slits 4a, 4b as shown in FIGS. 2 and 3 are formed in the contact surface 2 of the rubber elastic body 1. Specifically, in this embodiment, a plurality of first cuts 4a are formed along a first direction X, and a plurality of second cuts 4b are formed along a second direction Y perpendicular to the first direction X. The first cuts 4a are arranged parallel to one another, and the second cuts 4b are arranged parallel to one another. In other words, the first cuts 4a and the second cuts 4b (hereinafter, the first cuts 4a and the second cuts 4b may be collectively referred to as cuts 4) are arranged in a lattice pattern intersecting perpendicularly.

[0015] In this embodiment, as shown in Figure 2, both ends of the slit 4 in the longitudinal direction (the direction in which the slit 4 extends) are arranged to penetrate the side surface 1a of the rubber elastic body 1, but only one end in the longitudinal direction may penetrate the side surface 1a of the rubber elastic body 1, or both ends in the longitudinal direction may terminate within the rubber elastic body 1.

[0016] The multiple cuts 4 can be formed, for example, using a jig 20 as shown in Fig. 4. In the jig 20, multiple blades 22 are connected and fixed by connectors 24 so that the blade edges 22a are parallel to each other while being spaced apart from each other.

[0017] To form the multiple cuts 4 using the jig 20, the jig 20 is positioned so that the multiple blades 22 are aligned in the second direction Y, and the multiple blades 22 are moved in the first direction X while pressed against the contact surface 2 of the rubber elastic body 1 to form the multiple first cuts 4a. Thereafter, the jig 20 is positioned so that the multiple blades 22 are aligned in the first direction X, and the multiple blades 22 are moved in the second direction Y while pressed against the contact surface 2 of the rubber elastic body 1 to form the multiple second cuts 4b. In this way, the multiple cuts 4 arranged in a grid pattern are formed in the contact surface 2 of the rubber elastic body 1.

[0018] The cross-sectional shape of the slit 4 can be any shape, such as rectangular or triangular, but is preferably a shape in which the groove width narrows toward the groove bottom, as shown in FIG. 3 . The groove width and depth of the slit 4 can be set to any size. For example, the groove width of the slit 4 can be set to 0.1 mm or more and 0.5 mm or less. The depth of the slit 4 can be set to 0.1 mm or more and 0.5 mm or less. When the groove width of the slit 4 is 0.1 mm or more and the depth is 0.1 mm or more, the workability of the injection step of injecting the paint 5 into the slit 4 is improved, and when the groove width of the slit 4 is 0.5 mm or less and the depth is 0.5 mm or less, changes in the rigidity of the rubber elastomer 1 due to the formation of the slit 4 can be suppressed.

[0019] The spacing between adjacent cuts 4, i.e., the spacing between first cuts 4a adjacent in the second direction Y and the spacing between second cuts 4b adjacent in the first direction X, can be any size, but is preferably larger than the groove width of the cuts 4, for example, 1 mm or more and 2 mm or less.

[0020] (3) Injection process In the injection process, paint is injected into the multiple cuts 4 formed in the contact surface 2 of the rubber elastic body 1 in the cut formation process. Specifically, as shown in FIG. 5(a), first, paint is applied to one flat surface 30a of the flat plate member 30 to form a paint film 32. It is preferable that the thickness of the paint film 32 is greater than the depth of the cuts 4 formed in the rubber elastic body 1.

[0021] Next, as shown in Figure 5(b), the contact surface 2 of the rubber elastic body 1, on which the multiple slits 4 are formed, is pressed against the coating film 32 formed on the flat plate member 30. This allows the paint 5 to be injected into the multiple slits 4 provided on the contact surface 2 all at once.

[0022] Next, as shown in Figure 5(c), the contact surface 2 of the rubber elastomer 1 is removed from the flat plate member 30, and the paint 7 adhering to the contact surface 2 is wiped off. As a result, the paint 5 injected into the slits 4 remains, and multiple marks 6 made of the slits 4 where the paint 5 was injected are provided on the contact surface 2 of the rubber elastomer 1, and a sample piece such as that shown in Figure 5(d) is obtained.

[0023] (4)Measurement process Using the rubber elastic body 1 having the plurality of marks 6 formed on the contact patch 2 as described above as a test piece, a measuring machine 10 shown in Fig. 6 is used to measure the strain that occurs on the contact patch 2 where the rubber elastic body 1 comes into contact with the test road surface 11. Note that the configuration of the measuring machine used in the contact patch observation method according to the present invention is not limited to this.

[0024] The measuring device 10 comprises a test road surface 11 for contacting the test piece, a rubber elastic body 1, a support device 12 for supporting the rubber elastic body 1, a photographing device 13 for photographing the contact surface 2 of the rubber elastic body 1, and a processing device 14 for performing processing to calculate the strain generated on the contact surface 2.

[0025] A transparent portion 11a is provided on at least a portion of the test road surface 11. The transparent portion 11a is formed of a transparent plate material such as acrylic or glass. The surface of the transparent portion 11a is formed to be flat. The support device 12 is configured to allow the rubber elastic body 1 to move back and forth in a direction perpendicular to the test road surface 11 (the up and down direction in FIG. 6), and a load corresponding to the distance between the rubber elastic body 1 and the test road surface 11 is input to the rubber elastic body 1. The support device 12 also has a known mechanism for applying shear stress to the rubber elastic body 1, simulating the state in which a driving force, braking force, slip angle, camber angle, etc. are applied to a tire.

[0026] The photographing device 13 is equipped with multiple cameras (two in this embodiment). The multiple cameras are each arranged on the opposite side of the test road surface 11 from the rubber elastic body 1, and can photograph the contact surface 2 of the rubber elastic body 1 that has been placed in contact with the test road surface 11 through the transparent portion 11a. In this embodiment, the camera that constitutes the photographing device 13 is a high-speed camera, but is not limited to this.

[0027] The photographing device 13 performs a first photographing process in which the contact surface 2 of the rubber elastic body 1 is photographed by a plurality of cameras in a first state, and a second photographing process in which the contact surface 2 of the rubber elastic body 1 is photographed by a plurality of cameras in a second state different from the first state.

[0028] In this embodiment, for example, the deformation of the contact surface 2 when the state is changed from a first state in which a shear stress simulating the state in which the contact surface 2 is in contact with the test road surface 11 and the tire is rolling is applied to the rubber elastic body 1 to a second state in which a shear stress simulating the state in which a braking force is applied to the tire on the test road surface 11 is applied to the rubber elastic body 1 is calculated as strain.

[0029] In other words, the photographing device 13 outputs an image of the contact surface 2 of the rubber elastic body 1 in a first state photographed in the first photographing process (hereinafter referred to as the first photographed image) and an image of the contact surface 2 of the rubber elastic body 1 in a second state photographed in the second photographing process (hereinafter referred to as the second photographed image) to the processing device 14, and the processing device 14 calculates the deformation of the contact surface 2.

[0030] The processing device 14 is composed of a computer and calculates the distortion occurring in the contact surface 2 based on the first and second captured images input from the photographing device 13. The processing device 14 analyzes the captured images using, for example, a sampling moiré method to calculate the deformation of the contact surface 2. Specifically, the processing device 14 smooths the first and second captured images in a certain direction and performs thinning and linear interpolation on the smoothed images to generate a moiré fringe image of the grid-like markings 6. The processing device 14 calculates the three-dimensional shape of the contact surface 2 of the rubber elastic body 1 in the first state and the second state based on the generated moiré fringe images, thereby calculating the deformation of the rubber elastic body 1. Note that, in addition to the sampling moiré method described above, the processing device 14 can also use methods such as a Fourier transform grid method and a spatial fringe analysis method to measure the deformation of the contact surface 2 of the rubber elastic body 1 based on the images photographed by the photographing device 13.

[0031] In the method for observing the contact surface of a rubber elastic body 1 of this embodiment as described above, the markings 6 formed on the contact surface 2 are composed of multiple cuts 4 arranged parallel to each other, so that a large number of markings 6 can be easily formed on the surface of the rubber elastic body.

[0032] In addition, in this embodiment, multiple blades 22 arranged parallel to each other are pressed against the contact surface 2 of the rubber elastic body 1 while being moved to simultaneously form multiple cuts 4, so that multiple marks 6 can be formed on the contact surface 2 of the rubber elastic body 1 in a short period of time.

[0033] Furthermore, in this embodiment, the slit 4 is provided so as to penetrate the side surface 1a of the rubber elastic body 1, so that deformation occurring at the peripheral edge of the contact surface 2 can also be measured with high precision.

[0034] In addition, in this embodiment, the distance between adjacent slits 4 is greater than the groove width of the slits 4, so that a large number of marks 6 can be placed on the contact surface 2 while suppressing changes in the friction coefficient of the contact surface 2 caused by forming the slits 4, and the deformation occurring on the contact surface 2 of the rubber elastic body 1 can be measured accurately.

[0035] The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0036] 1...rubber elastic body, 2...contact surface, 3...sipe, 4...notch, 5...paint, 6...mark, 10...measuring machine, 11...test road surface, 12...support device, 13...photographing device, 14...processing device, 20...jig, 22...blade, 24...connecting body, 30...flat plate member, 32...paint film

Claims

1. a mark forming step of forming a mark on the contact surface of the rubber elastic body; an imaging step of imaging the contact surface of the rubber elastic body, on which the mark is formed, in contact with a road surface, with a camera, The mark forming process is a method for observing the contact surface of a rubber elastic body, the method comprising: a cut forming process for forming a plurality of first cuts arranged parallel to each other along a first direction and a plurality of second cuts arranged parallel to each other along a second direction perpendicular to the first direction, and forming the plurality of cuts so that at least one of the longitudinal directions of the cuts penetrates the side of the rubber elastic body; and an injection process for injecting paint into the plurality of cuts.

2. 2. The method for observing a ground contact patch according to claim 1, wherein the distance between adjacent cuts is greater than the groove width of the cuts.

3. 3. The method for observing a contact patch according to claim 1, wherein the slit forming step forms the slits by moving a plurality of blades arranged parallel to one another while pressing them against the rubber elastic body.

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