Method for manufacturing sample for friction test, and the sample and friction test method

Abstract

To provide a method for easily producing a sample for a friction test that enables accurate grasping of friction characteristics, the sample, and a friction test method using the sample.SOLUTION: There is provided a method for producing a sample for a friction test, comprising a modeling process using a three-dimensional printer 6. The modeling process comprises: irradiating a predetermined liquid material M accommodated in a container 9 with UV light from an irradiation head 7 to model into a desired shape; and curing to laminate into a layered shape; forming a flat plate-like body 1A having desired recesses 3a and protrusions 3b on one surface 2 and a Shore A hardness of 85 or less; and in the modeling process, preventing the modeling of a support member integrated with the flat plate-like body 1A using the predetermined material M. The flat plate-like body 1A is used as a friction test sample 1, and the sample is slid with one side 2 facing a target surface 10 while being pressed, and dynamic friction characteristics are measured.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a method for producing a sample for a friction test, the sample, and a friction test method, and more particularly to a method for easily producing a sample for a friction test whose friction characteristics can be accurately grasped, the sample, and a friction test method using the sample. [Background technology]

[0002] One of the performance characteristics of a tire is its friction characteristics. These friction characteristics change depending on the tread pattern. For example, to confirm the friction performance of various tread patterns, the dynamic friction coefficient is measured using friction test samples (block-shaped samples) of each tread pattern. To produce these samples, a vulcanization mold is required for each tread pattern, so it takes a lot of time and costs to produce samples of many different tread patterns.

[0003] In recent years, various types of three-dimensional printers (3D printers) have been developed, and it has been proposed to use 3D printers to manufacture test samples (see, for example, Patent Document 1). By using a 3D printer, it is possible to manufacture friction test samples of various tread patterns in a shorter time. As illustrated in FIG. 8, when a sample 11 is generally manufactured using a 3D printer, a support member 11a integrated with the main body of the sample 11 is simultaneously formed in addition to the main body of the sample 11. This support member 11a is then removed from the main body of the sample 11 to complete the sample 11. Since the sample 11 manufactured in this manner has a shape distortion caused by the support member 11a, it may not be possible to accurately grasp the original friction characteristics due to the tread pattern. Therefore, there is room for improvement in easily manufacturing a friction test sample that can accurately grasp the friction characteristics. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-80096 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a method for easily producing a sample for a friction test that enables friction characteristics to be accurately grasped, the sample, and a friction test method using the sample. [Means for solving the problem]

[0006] In order to achieve the above object, the manufacturing method of a friction test sample of the present invention is a manufacturing method of a friction test sample in which a specified material is shaped and hardened using a three-dimensional printer to manufacture a friction test sample, and is characterized in that in the manufacturing step of the specified material, the specified material is shaped into a plate-like body having a desired uneven shape on one side and hardened to have a Shore A hardness of 85 or less, without forming a support member using the specified material.

[0007] The friction test sample of the present invention is a friction test sample formed from a specified material using a three-dimensional printer, characterized in that the sample has no traces of the removal of a support member formed from the specified material, is a flat plate-like body having a desired uneven shape on one side, and has a Shore A hardness of 85 or less.

[0008] The friction test method of the present invention is a friction test method using the sample manufactured by the above-mentioned manufacturing method for a friction test sample, and is characterized in that the one surface of the sample is opposed to a target surface, and the sample is slid while being pressed against the target surface, thereby measuring dynamic friction characteristics. Effect of the Invention

[0009] According to the method for producing a friction test sample of the present invention, it is possible to easily produce samples having various uneven shapes on one side in a short time by using a three-dimensional printer. In addition, since a support member integrated with the sample is not produced, the produced sample does not suffer from distortion due to the support member. As a result, according to the present invention, it is advantageous to accurately grasp the friction characteristics due to the uneven shape on one side of a sample having a Shore A hardness of 85 or less and a certain degree of flexibility. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is an explanatory diagram illustrating an embodiment of a sample for a friction test in a plan view. [Diagram 2] 2 is an explanatory diagram illustrating an embodiment of the sample in FIG. 1 in a side view. FIG. [Diagram 3] FIG. 11 is an explanatory diagram illustrating another embodiment of the sample in a plan view. [Figure 4] 4 is an explanatory diagram illustrating an embodiment of the sample of FIG. 3 in a side view. FIG. [Diagram 5] 2 is an explanatory diagram illustrating an embodiment of the sample of FIG. 1 fixed to a holding plate in a plan view. FIG. [Figure 6] 6 is a side view illustrating a friction test using the sample embodiment of FIG. 5. FIG. [Figure 7] 2 is an explanatory diagram illustrating a process for producing the sample for friction test of FIG. 1 in a side view. FIG. [Figure 8] FIG. 13 is an explanatory diagram illustrating a conventional sample as viewed from the side. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a method for producing a sample for a friction test, the sample, and a friction test method of the present invention will be described based on the embodiments shown in the drawings.

[0012] A friction test sample 1 (hereinafter referred to as sample 1) of the present invention illustrated in Fig. 1 and Fig. 2 is manufactured by shaping and hardening a predetermined material M using a three-dimensional printer 6 (hereinafter referred to as 3D printer 6) illustrated in Fig. 7. The manufacturing method of sample 1 will be described later. This sample 1 is a flat plate having a desired uneven shape on one side 2, and has a Shore A hardness of 85 or less. The X, Y, and Z arrows in the figures respectively indicate the length direction, width direction, and thickness direction of sample 1, which are perpendicular to each other.

[0013] More specifically, the sample 1 has one surface 2 formed with recesses 3a and protrusions 3b of desired specifications, and the other surface 4 is a simple flat surface. The thickness of this flat sample 1 is, for example, 1 mm to 150 mm, the length is, for example, 10 mm to 50 mm, and the width is, for example, 10 mm to 50 mm.

[0014] In the sample 1 illustrated in FIGS. 1 and 2, the convex portions 3b are simple rectangular parallelepipeds and are square in plan view. The convex portions 3b are arranged in four rows at equal intervals in the length direction and width direction of the sample 1, so that a total of 16 convex portions 3b are arranged. The gaps between these convex portions 3b form the concave portions 3a. In another embodiment of the sample 1 illustrated in FIGS. 3 and 4, the concave portions 3a are simple rectangular parallelepiped depressions and are square in plan view. The concave portions 3a are arranged in four rows at equal intervals in the length direction and width direction of the sample 1, so that a total of 16 concave portions 3a are arranged. The gaps between these concave portions 3a form the convex portions 3b.

[0015] The recesses 3a and the protrusions 3b may have any desired shape, such as a circle, an ellipse, a rectangle, a square, a polygon having pentagons or more, a curved elongated shape, a bent elongated shape, or a combination of a plurality of these shapes.

[0016] The size, number, and arrangement of the recesses 3a and protrusions 3b can be set to a desired size, number, and arrangement within the range in which they can be formed on the sample 1. The depth (maximum depth) of the recesses 3a and the height (maximum height) of the protrusions 3b are, for example, 0.1 mm or more and 20 mm or less.

[0017] When performing a friction test on this sample 1 assuming that it is the tread portion of a tire, one side 2 is pressed against and slid against a target surface 10 assuming that the tire will run on, as shown in Fig. 6. Thus, samples 1 having various desired uneven shapes assuming tread patterns on one side 2 are manufactured.

[0018] The Shore hardness is a value measured by a Type A durometer based on the standard JIS K6253-3: 2012. In order to make Sample 1 more similar to vulcanized rubber, the Shore A hardness of Sample 1 is, for example, preferably 80 or less, and more preferably 75 or less.

[0019] 7, the sample 1 is manufactured using a 3D printer 6, but the modeling method of the 3D printer 6 is not particularly limited, and various known methods such as a photolithography method and a fused deposition modeling method can be adopted. In this embodiment, a DPL type 3D printer 6, which is a type of photolithography method, is used.

[0020] This 3D printer 6 is of known specifications having an irradiation head 7, a platform 8 for holding the sample 1, and a material container 9 in which the predetermined material M is contained. UV light is irradiated from the irradiation head 7 in a planar manner toward the bottom surface of the material container 9 in which the liquid predetermined material M is contained. Since the predetermined material M is hardened by the UV light, the platform 8 is moved upward little by little, and the predetermined material M is molded into a desired shape little by little in the thickness direction. By stacking the predetermined material M in layers in the desired shape in this way, the predetermined material M is molded and hardened into a flat plate-like body 1A having a desired uneven shape on one side 2. In the stereolithography method, since excess predetermined material M is attached to the molded flat plate-like body 1A, the unnecessary predetermined material M is removed and washed. In addition, the molded flat plate-like body 1A is subjected to a secondary hardening process as necessary. The flat plate-like body 1A molded in this way becomes the sample 1.

[0021] In this manufacturing method, a support member 11a integrated with the sample 11, as exemplified in Fig. 8, is not manufactured. That is, as exemplified in Fig. 7, the specified material M is shaped and hardened with zero inclination relative to the platform 8 (parallel to the platform 8). In this way, the sample 1 is manufactured without manufacturing a support member. Therefore, distortions and the like caused by the support member do not occur in this sample 1. Since this sample 1 is manufactured without a support member, there is no trace of the removal of the support member shaped from the specified material M.

[0022] The predetermined material M may be any material that can be used in the 3D printer 6, and the type of the predetermined material M that can be used is determined by the modeling method of the 3D printer 6. When the modeling process is a photolithography method, various known UV curing resins can be used as the predetermined material M, and for example, acrylate or isobornyl acrylate is used.

[0023] When the molding process is a fused deposition modeling method, various known resins that melt by heat can be used as the predetermined material M. Examples of the predetermined material M that can be used include ABS resin, PVA resin, polycarbonate, urethane resin, nylon resin, and PLA resin.

[0024] A 3D printer 6 using a stereolithography method (DPL method or SLA method) as in this embodiment is advantageous for forming a detailed uneven shape (advantageous in terms of resolution). On the other hand, the fused deposition modeling method is suitable for making the hardness of the sample 1 similar to that of vulcanized rubber, since it is possible to use a predetermined material M that is more flexible and similar to vulcanized rubber. However, since the fused deposition modeling method has a lower resolution than the stereolithography method, the stereolithography method is used when priority is given to forming a desired uneven shape with high accuracy.

[0025] When performing a friction test using this sample 1, the other surface 4 of the sample 1 is joined to a holding plate 5 as illustrated in Figs. 5 and 6. The holding plate 5 is a rigid body such as a metal plate, and the surface facing the other surface 4 is a simple flat surface. The other surface 4 and the holding plate 5 are firmly joined using an adhesive or the like. If the support member is not formed at the same time as the main body of the sample 1 during the manufacture of the sample 1, the flat sample 1 may be slightly warped. However, even if the sample 1 is slightly warped, by joining the other surface 4 to the holding plate 5, the one surface 2 returns to its original state without warping.

[0026] One surface 2 of the sample 1 integrated with the holding plate 5 is opposed to and pressed against the target surface 10. In this state, the target surface 10 and the sample 1 are moved relatively along the target surface 10 to slide the sample 1 and measure the dynamic friction characteristics. The target surface 10 may be fixed at a fixed position and the sample 1 moved, or the sample 1 may be fixed at a fixed position and the target surface 10 moved. By performing the friction test in this manner, the dynamic friction coefficient of the sample 1 with respect to the target surface 10 is grasped as the dynamic friction characteristic of the sample 1. The dynamic friction characteristic of the sample 1 can be measured by employing various known friction tests.

[0027] As described above, by using the 3D printer 6, the sample 1 having various uneven shapes on the one side 2 can be easily manufactured in a short time. In addition, since a support member integrated with the sample 1 is not manufactured when manufacturing the sample 1, the manufactured sample 1 does not suffer from distortion or the like caused by the support member. Therefore, even if the sample 1 has a Shore A hardness of 85 or less and is somewhat flexible, it is advantageous for accurately grasping the friction characteristics caused by the uneven shape of the one side 2.

[0028] The surface of the protrusions 3b that contact the target surface 10 during the friction test preferably has an arithmetic mean height Sa of 5 μm or less, more preferably 2 μm or less. The arithmetic mean height Sa is a value measured in accordance with ISO 25178. By setting the calculated mean height Sa of the surface of the protrusions 3b to 5 μm or less, the effect of the surface roughness of the protrusions 3b on the friction characteristics of the sample 1 is eliminated, which is even more advantageous in accurately grasping the original friction characteristics of the uneven shape of the one side 2.

[0029] To grasp the dynamic friction characteristics of the sample 1 without variation, a certain amount of contact area with the target surface 10 is necessary. Therefore, when the pressing force applied to the sample 1 toward the target surface 10 is 0.16 MPa, it is advisable to set the contact area between the one side 2 and the target surface 10 relative to the total area of ​​the one side 2 in a plan view to 30% or more and 90% or less. In the case of the sample 1 illustrated in Figs. 1 to 4, this contact area is the total area of ​​the top faces of the protrusions 3.

[0030] In order to grasp the difference in dynamic friction characteristics caused by various uneven shapes of the one side 2, for example, multiple types of samples 1 are prepared in which the uneven shapes of the one side 2 are different and the contact area with the target surface 10 is set to be the same. Then, the above-mentioned friction test is performed on each sample 1 to measure the dynamic friction characteristics (dynamic friction coefficient). In addition, a feature quantity that characterizes the uneven shape of the one side 2 of each sample 1 is specified. Examples of this feature quantity include the area of ​​one recess 3a or protrusion 3 in a plan view (i.e., the size of one recess 3a or protrusion 3), the interval between adjacent recesses 3a, the interval between adjacent protrusions 3, the length of the contour line of one recess 3a or protrusion 3 in a plan view, the number of bending points on this contour line, and the ratio of straight and non-straight parts on this contour line. A combination of multiple types of these feature quantities can also be used as the feature quantity.

[0031] Then, a correlation is obtained between the measured dynamic friction characteristics of each sample 1 and the feature quantity that characterizes the uneven shape of each sample 1. By obtaining this correlation, the feature quantity that realizes the desired dynamic friction characteristics is identified, so that the sample 1 will exhibit the desired dynamic friction characteristics by making one side 2 into an uneven shape that has this feature quantity. In other words, by obtaining this correlation, it is possible to specify, to a certain extent, a tread pattern that exhibits the desired dynamic friction characteristics. As a result, it is advantageous to develop a tire having a tread portion that exhibits the desired dynamic friction characteristics with high accuracy in a shorter time. EXAMPLES

[0032] A total of six samples, three types of samples (samples 1 to 3) having one surface with an uneven shape as shown in Figures 1 and 2, and three types of samples (samples 4 to 6) having one surface with an uneven shape as shown in Figures 3 and 4, were manufactured by the DPL method without using a support member as described above, and the dynamic friction coefficient of each sample was measured by conducting a friction test as shown in Figure 6. Table 1 shows the specifications of each sample and the measurement results of the dynamic friction coefficient.

[0033] The material (specified material) of each sample is acrylic resin, the Shore A hardness is 50, the arithmetic mean height Sa of the convex surface on one side is 5 μm or less, and the contact area with the target surface in the friction test is 256 mm 2 The differences between the samples are essentially only the specifications shown in Table 1. The dynamic friction coefficients in Table 1 are expressed as an index, with the dynamic friction coefficient of sample 3 being the standard 100. The higher the index value, the higher the dynamic friction coefficient. Note that in Table 1, the number of recesses in samples 1 to 3 is listed as "-", but in reality, the gaps between the respective protrusions exist as recesses. Similarly, the number of protrusions in samples 4 to 6 is listed as "-", but in reality, the gaps between the respective recesses exist as protrusions.

[0034] [Table 1]

[0035] From the results in Table 1, it can be clearly seen that the dynamic friction characteristics differ due to the uneven shape of one side of each sample.

[0036] The present disclosure includes the following inventions. Invention 1: A method for manufacturing a sample for a friction test, comprising the steps of: forming a predetermined material using a three-dimensional printer and hardening the material to manufacture a sample for a friction test; A manufacturing method for a friction test sample in which, in the process of forming the specified material, a support member is not formed using the specified material, but the specified material is formed into a flat plate having a desired uneven shape on one side and hardened to have a Shore A hardness of 85 or less. Invention 2: 2. The method for producing a sample for a friction test according to claim 1, wherein the surface of the convex portions of the uneven shape on one side of the sample has an arithmetic mean height Sa of 5 μm or less. Invention 3: 3. The method for producing a sample for a friction test according to claim 1 or 2, wherein a photolithography method is adopted for the modeling step. Invention 4: 4. The method for producing a sample for a friction test according to any one of Inventions 1 to 3, wherein acrylate or isobornyl acrylate is used as the predetermined material. Invention 5: In a friction test sample in which a predetermined material is formed using a three-dimensional printer, The sample for friction testing has no traces of the removal of the support member made of the specified material, is a flat plate having a desired uneven shape on one side, and has a Shore A hardness of 85 or less. Invention 6: A friction test method using a sample manufactured by the manufacturing method of a friction test sample according to any one of claims 1 to 4, A friction testing method in which the one surface of the sample is opposed to a target surface and slid while being pressed against the target surface to measure dynamic friction characteristics. Invention 7: The friction testing method according to claim 6, wherein when a pressing force of 0.16 MPa is applied to the sample toward the target surface, the contact area between the one surface and the target surface is set to 30% or more relative to the total area of ​​the one surface in a plan view. Invention 8: A friction testing method according to invention 6 or 7, comprising preparing a plurality of types of samples each having a different uneven shape on the one surface and the same contact area with the target surface, and obtaining a correlation between the measured dynamic friction characteristics of each of the samples and a feature quantity that characterizes the uneven shape of each of the samples. [Explanation of symbols]

[0037] 1 Sample 1A flat plate 2 One side 3a Recess 3b Convex part 4 Other side 5 Holding plate 6. 3D Printer 7 Irradiation head 8. Platform 9 Material container 10 Target Surface 11 Conventional Samples 11a Support material M Specified material

Claims

1. A method for manufacturing a sample for a friction test, comprising the steps of: forming a predetermined material using a three-dimensional printer and hardening the material to manufacture a sample for a friction test; In the manufacturing process of the friction test sample, the specified material is shaped into a flat plate having a desired uneven shape on one side and hardened to have a Shore A hardness of 85 or less, without forming a support member using the specified material.

2. 2. The method for producing a sample for a friction test according to claim 1, wherein the surface of the convex portions of the uneven shape on one side of the sample has an arithmetic mean height Sa of 5 μm or less.

3. The method for producing a sample for a friction test according to claim 1 , wherein a photolithography method is adopted for the forming step.

4. 2. The method for producing a sample for a friction test according to claim 1, wherein the predetermined material is an acrylate or isobornyl acrylate.

5. In a friction test sample in which a predetermined material is formed using a three-dimensional printer, The sample for friction test has no traces of the removal of the support member made of the specified material, is a flat plate having a desired uneven shape on one side, and has a Shore A hardness of 85 or less.

6. A friction test method using a sample manufactured by the method for manufacturing a friction test sample according to any one of claims 1 to 4, comprising the steps of: A friction testing method in which the one surface of the sample is opposed to a target surface and slid while being pressed against the target surface to measure dynamic friction characteristics.

7. 7. The friction testing method according to claim 6, wherein when a pressing force applied to the sample toward the target surface is 0.16 MPa, a contact area between the one surface and the target surface is set to 30% or more relative to a total area in a plan view of the one surface.

8. 7. The friction testing method according to claim 6, further comprising the steps of: preparing a plurality of types of samples each having a different uneven shape on the one surface and a same contact area with the target surface; and obtaining a correlation between the measured dynamic friction characteristics of each of the samples and a feature quantity that characterizes the uneven shape of each of the samples.

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