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 hole forming step of forming multiple holes 4 by pressing multiple needle-like members 22 against the rubber elastic body 1, and an injection step of injecting paint 5 into the multiple holes 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 a large number of marks on the surface of the rubber elastomer, photograph the surface of the rubber elastomer together with the large number of marks while applying shear deformation to the rubber elastomer, and analyze the image of the rubber elastomer containing the large number of 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 in 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 with the marks formed on it while it is in contact with the road surface, and the marking formation process includes a hole formation process for pressing a plurality of needle-shaped members against the rubber elastic body to form a plurality of holes, and an injection process for injecting paint into the plurality of holes. [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 having a plurality of holes formed therein. [Figure 3] Cross section AA of Figure 2 [Figure 4] FIG. [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 hole forming step (step S2) of forming multiple holes 4 in the contact surface 2 of the rubber elastomer 1, an injection step (step S3) of injecting paint 5 into the multiple holes 4 to form multiple marks 6, and a measurement step (step S4) of using a measuring device 10 to measure the strain generated in the contact surface 2 using the rubber elastomer 1 with the multiple marks 6 formed as a test piece.

[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 a plurality of sipes 3 are provided on a contact surface 2 that is pressed against a test road surface 11 of a measuring device 10. The sipes 3 are elongated grooves with a groove width of 1.5 mm or less. In this embodiment, the sipes 3 are provided so as to penetrate the periphery of the rubber elastic body 1, but they may also terminate within the rubber elastic body 1. Furthermore, although the sipes 3 are entirely linear, they may also be sipes that include a corrugated portion having a corrugated cross-sectional shape.

[0014] (2) Hole forming process In the hole forming step, a plurality of holes 4 are formed in the contact surface 2 of the rubber elastic body 1 as shown in FIGS.

[0015] Specifically, a plurality of needle-like members 22 provided on a drilling jig 20 are pressed against the contact surface 2 of the rubber elastic body 1 to form a plurality of holes 4 in the contact surface 2. As shown in FIG. 4 , the drilling jig 20 has a flat base 24 on which a plurality of needle-like members 22 protruding from one surface 24a. The drilling jig 20 is placed so that one surface 24a faces the contact surface 2 of the rubber elastic body 1, and then at least one of the drilling jig 20 and the rubber elastic body 1 is moved so that the one surface 24a comes into surface contact with the contact surface 2. As a result, the multiple needle-like members 22 provided on the one surface 24a of the drilling jig 20 simultaneously pierce the contact surface 2 of the rubber elastic body 1, and a plurality of holes 4 are formed in the contact surface 2 at once.

[0016] In this embodiment, the planar shape of the holes 4 is circular, but it can be any shape, such as rectangular or triangular. The diameter of the holes 4 is, for example, 0.2 mm or more and 1 mm or less. The diameters of the multiple holes 4 may all be the same, or there may be holes 4 with various diameters within a predetermined range. The depth of the holes 4 is, for example, 0.1 mm or more and 1 mm or less. The spacing between adjacent holes 4 may be any spacing that prevents the holes 4 from overlapping, and is, for example, 0.2 mm or more and 1.5 mm or less.

[0017] Furthermore, when multiple sipes 3 are formed on the contact surface 2 as in this embodiment, it is preferable that the spacing between adjacent sipes 3, i.e., the spacing between adjacent holes 4, is smaller than the distance between the sipes 3 at their closest positions.

[0018] Furthermore, it is preferable that a plurality of holes 4 be provided along the periphery of the rubber elastic body 1 in an area at a distance of 0.2 mm to 1.5 mm from the periphery of the rubber elastic body 1 .

[0019] (3) Injection process In the injection process, paint is injected into the multiple holes 4 formed in the contact surface 2 of the rubber elastic body 1 in the hole 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 coating film 32. It is preferable that the thickness of the coating film 32 is greater than the depth of the holes 4 formed in the rubber elastic body 1.

[0020] Next, as shown in Figure 5(b), the contact surface 2 of the rubber elastic body 1, in which the plurality of holes 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 plurality of holes 4 formed in the contact surface 2 all at once.

[0021] Next, as shown in Figure 5(c), the contact surface 2 of the rubber elastic body 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 holes 4 remains, and a sample piece is obtained on the contact surface 2 of the rubber elastic body 1, with multiple marks 6 made of holes 4 into which the paint 5 has been injected, as shown in Figure 5(d).

[0022] (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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] In this embodiment, for example, a first state is defined as a state in which a force 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, and a second state is defined as a state in which a force 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, and the deformation of the contact surface 2 when changing from the first state to the second state is calculated as strain.

[0028] 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.

[0029] The processing device 14 is composed of a computer and calculates the strain 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 digital image correlation method to calculate the deformation of the contact surface 2. The processing device 14 performs pattern matching on the first and second captured images to determine the amount of displacement of the pattern consisting of multiple markers 6 and calculates the deformation of the rubber elastic body 1 as strain. Note that, in addition to the digital image correlation method described above, the processing device 14 can also use the Fourier grid method, sampling moiré method, etc. to measure the deformation of the contact surface 2 of the rubber elastic body 1 based on the images captured by the photographing device 13.

[0030] (5) Effects In the method for observing the contact surface of a rubber elastic body 1 of this embodiment as described above, multiple needle-shaped members 22 are pressed against the contact surface 2 of the rubber elastic body 1 to form multiple holes 4, so that multiple marks 6 can be easily provided on the surface of the rubber elastic body 1.

[0031] In addition, in this embodiment, by pressing a drilling jig 20 having multiple needle-shaped members 22 against the contact surface 2 of the rubber elastic body 1, the multiple needle-shaped members 22 simultaneously pierce the contact surface 2 of the rubber elastic body 1, and multiple holes 4 are formed in the contact surface 2 at once, so that a large number of marks 6 can be formed on the contact surface 2 of the rubber elastic body 1 in a short period of time.

[0032] In addition, in this embodiment, by pressing the contact surface 2 of the rubber elastic body 1, in which multiple holes 4 have been formed, against the coating film 32 formed on one surface 30a of the flat plate member 30, paint 5 can be injected into the multiple holes 4 at once, and therefore, 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, multiple holes 4 are provided in the contact surface 2 of the rubber elastic body 1 so that the distance between adjacent holes 4 is smaller than the distance between adjacent sipes 3, and therefore multiple marks 6 can be formed in each rubber portion separated by the sipes 3. This makes it possible to determine the amount of displacement of the pattern made up of multiple marks 6 for each rubber portion separated by the sipes 3, and to accurately calculate the deformation of each rubber portion.

[0034] 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]

[0035] 1...rubber elastic body, 2...contact surface, 3...sipe, 4...hole, 5...paint, 6...mark, 10...measuring machine, 11...test road surface, 12...support device, 13...photographing device, 14...processing device, 20...hole drilling jig, 22...needle-shaped member, 24...base, 30...flat member, 32...paint film

Claims

1. A mark forming step of forming a mark on the contact surface of a rubber elastic body produced by molding vulcanized rubber into a predetermined shape; an imaging step of imaging the ground contact surface on which the mark is formed in a state of contact with a road surface, The mark forming process is a method for observing the contact surface of a rubber elastic body, which includes a hole forming process in which a plurality of needle-shaped members having pointed tips attached to a hole drilling jig are pressed against the rubber elastic body to form a plurality of holes, and an injection process in which paint is injected into the plurality of holes.

2. The rubber elastic body has a plurality of sipes, 2. The method for observing the contact patch of a rubber elastic body according to claim 1, wherein the spacing between the plurality of holes is smaller than the spacing between the sipes at the closest positions.

3. 3. A method for observing the contact surface of a rubber elastic body as described in claim 1 or 2, wherein the injection process comprises the steps of applying paint to a flat surface, and pressing the rubber elastic body having a plurality of holes formed therein against the paint applied to the flat surface to inject the paint into the plurality of holes.

4. A method for observing the contact surface of a rubber elastic body described in any one of claims 1 to 3, wherein the hole forming process forms the plurality of holes using a drilling jig having a base and a plurality of needle-shaped members protruding from the base.

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