JP2007320248A - Manufacturing method of pneumatic tire, vulcanizing mold, and pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a pneumatic tire to which mud hardly attaches, a vulcanizing mold, and a pneumatic tire. <P>SOLUTION: The pneumatic tire is molded by vulcanizing using the vulcanizing mold whose surface of a mold portion for molding a tread surface 14S and a side wall surface 20S is subjected to surface treatment by shot blasting using a blast material such as a glass based or plastic based materials whose surface has no sharp shape when manufacturing the pneumatic tire. Further, the blast material with a particle size between 200 and 800 μm is used. As a result, the mold surface of the vulcanizing mold is smooth and excellent in gloss. Furthermore, the surface roughness of the mold surface of the vulcanizing mold becomes in a range between 80 and 300 μm, which results in the formation of a tire having a surface to which mud hardly attaches. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire manufacturing method, a vulcanization mold, and a pneumatic tire that are optimal for use in agricultural machines such as tractors.

  Agricultural machines such as tractors are mainly paddy field and field running, but if traction is applied during these runnings, a strong force is applied to the tire in the soil, causing mud to adhere to the tire. From the conventional example, it has been regarded as important to prevent the adhesion of the mud (for example, see Patent Document 1).

  The mud adheres to the tire through moisture contained in the soil, but when the water film on the tire surface evaporates, the mud is directly stuck to the tire surface. On the other hand, the tractor may travel about 1 km after completing the work and entering the garage. In such a case, before returning to the vicinity of the garage and washing off the mud, the water film evaporates and mud adheres directly to the tire surface. When mud dries and sticks in this way, it often becomes a problem that mud does not fall off easily even after washing.

  By the way, when the tire surface roughness and the particle size of the mud are approximately the same, the mud particles get stuck in the recesses on the tire surface, so that the above-described sticking easily occurs. The kind of mud is classified into clay (particle size: 6 μm or less), silt (6 to 75 μm), fine sand (75 to 420 μm), and coarse sand (420 μm or more) in order from the smallest particle size. Of these, clay and silt-based soils are often found in the market, and soils with these particle sizes have smaller porosity between particles and are easier to adhere than soils with larger particle sizes. Sticking to tires is very strong.

In particular, it has been found that mud mainly composed of a part of silt (particle size of 6 to 50 μm) is most likely to stick to the tire surface. Therefore, when the surface roughness of the tire is about 6 to 50 μm, mud particles tend to get stuck on the tire surface and the mud itself tends to adhere to each other. .
JP-A-5-208454

  In view of the above facts, an object of the present invention is to provide a method for manufacturing a pneumatic tire in which mud does not easily adhere, a vulcanization mold, and a pneumatic tire.

  This inventor examined the cause of mud adhering easily in the conventional pneumatic tire. And in the vulcanization mold which vulcanizes-molds a pneumatic tire, especially in the case of a new article, it discovered that surface roughness was set to about 10-50 micrometers by implementation of finishing treatment.

  In the case of a tire manufactured with a new vulcanization mold, the surface roughness of the tire is about 10 to 50 μm because the surface roughness of the mold is about 10 to 50 μm. Here, as described above, since the particle diameter of the mud that is most likely to adhere is about 6 to 50 μm, the tire surface roughness is substantially equal to the particle diameter of the mud that is likely to adhere. In this case, the mud particles fit into the unevenness of the tire and the mud adhesion to the tire is promoted. Also, the attached mud is difficult to leave.

  Therefore, when traveling on a paddy field or field composed mainly of soil having a particle size in such a range, if the water film on the tire surface evaporates when traveling on the pavement after completion of the work, mud on the tire surface. Is stuck.

  Then, this inventor examined the cause of the surface roughness of a vulcanization mold being about 10-50 micrometers. As a result of investigations and experiments, the surface of the vulcanization mold was used because shot blasting used in the surface finishing process at the time of vulcanization mold production uses alumina metal powder as the blasting material. It was found that the roughness was about 10-50 μm.

  In addition, the inventor diligently studied the cause of the glossiness of the tire surface. It was noted that the metal powder used as the blast material had a sharp shape with a small particle size and a sharp portion. And by spraying such a hard metal powder on the surface of the vulcanization mold at a high pressure, it was found that the unevenness of the blasted mold surface was also sharpened, and a lot of sharp corners were formed. . Furthermore, the surface of the tire vulcanized with this mold is not glossy due to diffused reflection of light, and at first glance, it has been found that there is a case where the tire is stored for a long time after manufacturing and gives an impression like a deteriorated tire.

  Therefore, the present inventor diligently studied to prevent the unevenness of the mold surface from becoming a sharp shape.

  The present inventors have completed the present invention by carrying out the above examinations and conducting further experiments and further investigations.

  According to the first aspect of the present invention, at least the surface of the mold part for molding the tire tread surface and the tire side surface is shot blasted with a blasting material having a particle size in the range of 200 to 800 μm and a Mohs hardness of 3 to 7. Vulcanization molding is performed using a surface-treated vulcanization mold.

  The surface roughness of the mold part surface-treated with a blasting material having a particle size in the range of 200 to 800 μm is in the range of 80 to 300 μm, and the surface roughness of the tire surface part molded in the mold part is also 80 to It is in the range of 300 μm. Therefore, in the invention according to claim 1, the pneumatic tire is manufactured so that at least the surface roughness range of the tire tread surface and the tire side surface is different from the particle size range (6 to 50 μm) of the mud which is easily adhered. be able to. As a result, even when farming is performed in a field or the like using an agricultural machine equipped with this pneumatic tire, mud hardly adheres to the tire surface of the agricultural machine, and the adhering mud easily falls off. Therefore, even if the water film on the tire surface evaporates after the mud adheres, the amount of mud sticking to the tire surface is remarkably small.

  In the invention described in claim 1, since the vulcanized mold surface-treated by shot blasting with a blasting material having a Mohs hardness of 3 or more and 7 or less is used, the unevenness of the surface of the mold part becomes a gentle shape. . As a result, in the pneumatic tire obtained by vulcanization molding with the vulcanization mold, at least the tire tread surface and the tire side surface, which are important in appearance, are smooth and glossy. It is not damaged and greatly contributes to improving the appearance when new.

  The invention according to claim 2 is characterized in that the blast material is a glass-based or plastic-based blast material.

  In the invention according to claim 2, a general-purpose glass-based or plastic-based blast material not having a sharp shape is used as the blast material instead of a sharp metal powder, and the surface of the mold part is used. Processing is in progress. Therefore, at least the tire tread surface and the tire side surface can be made smooth and glossy with a general-purpose easily available blast material.

  The invention according to claim 3 is a vulcanization mold used for vulcanization molding of a pneumatic tire, wherein at least the surface of the mold part for molding the tire tread surface and the tire side surface has a particle size of 200 to 800 μm. And surface treatment by shot blasting with a blasting material having a Mohs hardness of 3 or more and 7 or less.

  The surface roughness of the mold part surface-treated with a blast material having a particle size in the range of 200 to 800 μm is in the range of 80 to 300 μm, and the surface roughness of the tire surface part molded in the mold part is also 80 to It is in the range of 300 μm. Therefore, in the invention according to claim 3, since the surface roughness range of at least the tire tread surface and the tire side surface is different from the particle size range of adhering mud (6 to 50 μm), it is molded by the mold part. Mud hardly adheres to the tire surface portion. As a result, even when farming is performed in a field or the like using an agricultural machine equipped with this pneumatic tire, mud hardly adheres to the tire surface of the agricultural machine, and the adhering mud easily falls off. Therefore, even if the water film on the tire surface evaporates after the mud adheres, the amount of mud sticking to the tire surface is remarkably small. In addition, if the surface roughness of the tire surface portion is smaller than 80 μm, mud tends to adhere, and if it is larger than 300 μm, the tire surface portion may be unevenly worn.

  In the invention according to claim 3, since the vulcanization mold surface-treated by shot blasting with a blasting material having a Mohs hardness of 3 or more and 7 or less is used, the unevenness of the surface of the mold part becomes a gentle shape. . As a result, in the pneumatic tire obtained by vulcanization molding with the vulcanization mold, at least the tire tread surface and the tire side surface, which are important in appearance, are smooth and glossy. Not damaged.

  The invention according to claim 4 is characterized in that the blast material is surface-treated with a glass-based or plastic-based blast material.

  In the invention according to claim 4, a general glass-type or plastic-type blast material not having a sharp shape is used as a blast material instead of a sharp metal powder, and the surface of the mold part is used. Processing is in progress. Therefore, at least the tire tread surface and the tire side surface are made smooth and glossy by a general-purpose easily available blast material.

  The invention according to claim 5 is characterized in that the surface roughness of at least the tire tread surface and the tire side surface is in the range of 80 to 300 μm, and the surface wavelength is 1.5 times or more of the surface roughness. To do.

  If the surface roughness is smaller than 80 μm, mud tends to adhere, and if it is larger than 300 μm, there is a concern that the tire surface portion is unevenly worn.

  Further, the surface wavelength is an interval between adjacent convex portions on the tire surface. The surface roughness corresponds to the wave amplitude on the tire surface. When the surface wavelength is 1.5 times or more of the surface roughness, it is possible to prevent the mud from further getting stuck and preventing the gloss from being easily generated due to irregular reflection.

  In the invention according to claim 5, when producing a pneumatic tire, a good pneumatic tire can be easily produced by vulcanization molding using the vulcanization mold according to claim 3.

  According to the invention described in claim 5, the tire surface portion which is important in appearance becomes a smooth surface, and the gloss of the tire surface portion is good. Further, it is possible to provide a pneumatic tire in which mud does not easily adhere to the tire surface and there is no concern about uneven wear.

  According to the present invention, it is possible to manufacture a pneumatic tire to which mud does not easily adhere, and to realize a vulcanization mold for manufacturing such a pneumatic tire.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. As shown in FIG. 1, a pneumatic tire 10 according to an embodiment of the present invention includes a carcass whose both ends are folded at bead cores, and a belt layer is provided on the outer side in the tire radial direction of the crown portion of the carcass. A tread portion 14 is formed on the outer side in the tire radial direction of the belt layer. In the tread portion 14, lugs 16 having a substantially trapezoidal cross section extending obliquely from the tire center to both sides in the tire width direction are arranged at predetermined intervals in the tire circumferential direction.

  Shoulder portions 18 are formed on both outer sides of the tread portion 14 in the tire width direction, and sidewall portions 20 are further formed.

  In the present embodiment, the tread portion 14, the shoulder portion 18, and the sidewall portion 20 each have a surface roughness within the range of 80 μm to 300 μm. In the present embodiment, the surface of the tread portion 14 includes the surface of each component such as a ground plane, a groove, and a depression, and the same applies to the surfaces of the shoulder portion 18 and the sidewall portion 20.

  In the vulcanization mold 22 (see FIG. 2) used for vulcanization molding of the pneumatic tire 10, the surface roughness of the surface 24S of the mold portion 24 that forms the tread portion 14, the shoulder portion 18, and the sidewall portion 20 is achieved. Are within the range of 80 μm to 300 μm. In this embodiment, the material of the vulcanization mold 22 is general aluminum.

  Moreover, in the vulcanization mold 22, the surface wavelength of the surface 24S of the mold part 24 is 1.5 times or more of the surface roughness. Therefore, also in the pneumatic tire 10, the surface wavelengths of the tread part 14, the shoulder part 18, and the sidewall part 20 are 1.5 times or more of the surface roughness. This prevents the mud from further getting stuck on the tire surface and prevents the gloss from being easily generated due to irregular reflection, so that the appearance when new is greatly improved.

  In the manufacture of the vulcanization mold 22, when the surface treatment of the surface 24S of the mold part 24 is performed, the surface treatment is performed by shot blasting using a glass or plastic blasting material having a particle size in the range of 200 to 800 μm. . As a result, the surface roughness of the surface 24S of the mold part 24 is in the range of 80 to 300 μm. In addition, the Mohs hardness of this glass-type or plastic-type blast material is 3-7.

In the present embodiment, the shot blasting condition is a pressure within the range of 4 to 7 kg / cm ² .

  When the pneumatic tire 10 is vulcanized and molded using the vulcanization mold 22, the surface roughness of the tread portion 14, the shoulder portion 18 and the sidewall portion 20 molded by the mold portion 24 is 80 μm to 300 μm. Within the range.

  Therefore, since it is outside the range of 6 to 50 μm where mud is most likely to adhere, mud is difficult to adhere to the tread portion 14, shoulder portion 18, and sidewall portion 20 of the pneumatic tire 10. Even if it adheres, it is easy to fall off.

  Further, in the manufacture of the vulcanization mold 22, the surface 24S of the mold part 24 is made of a glass or plastic blast material which is made of a material having a relatively low hardness as compared with a conventionally used blast material and does not have a sharp shape. Blast processing. Therefore, since the surface 24S of the mold portion 24 is a smooth surface, the tread surface 14S, the shoulder surface 18S, and the sidewall surface 20S, which are important parts in appearance, are also smooth and glossy.

<Test example>
In order to confirm the effect of the present invention, the present inventor firstly, an example of the vulcanization mold 22 of the above embodiment (hereinafter referred to as a vulcanization mold of an example) and an example of a conventional vulcanization mold (hereinafter referred to as a vulcanization mold) A conventional vulcanization mold) was prepared. Table 1 shows the surface treatment conditions by shot blasting for the vulcanization mold of the example and the vulcanization mold of the conventional example.

また、実施例の加硫モールドのモールド部表面を顕微鏡で撮影して得られた部分拡大図を図３に、従来例の加硫モールドのモールド部表面を顕微鏡で撮影して得られた部分拡大図を図５に、それぞれ示す。

Moreover, the partial enlarged view obtained by image | photographing the mold part surface of the vulcanization mold of an Example with a microscope is shown in FIG. 3, The partial expansion obtained by image | photographing the mold part surface of the vulcanization mold of a prior art example with a microscope The figure is shown in FIG.

  Furthermore, the present inventor made a pneumatic tire vulcanized and molded with the vulcanization mold of the example (hereinafter referred to as the pneumatic tire of the example) and a pneumatic tire vulcanized and molded with the vulcanization mold of the conventional example ( Hereinafter, it was referred to as a conventional pneumatic tire). The tire size is AGS 13.6 / 6-24. FIG. 4 is a partial enlarged view obtained by photographing the tread cross section of the pneumatic tire of the example with a microscope, and FIG. 6 is a partial enlarged view obtained by photographing the tread cross section of the pneumatic tire of the conventional example with a microscope. Respectively.

  And using these pneumatic tires, the amount of mud adhering to the tire surface was examined by running on a paddy field (the mud particle size is about 8 to 20 μm) to evaluate the performance.

  Agricultural machines equipped with tires were 34-horsepower tractors, all of which were mounted on the rear wheels and ran with 2WD (drive only the rear wheels). Both travel times are 10 minutes.

  In this experimental example, the mud adhering to the surface of each tire was dried after each run. Then, after traveling 100 m on the asphalt road surface, the amount of mud adhering to the groove between adjacent lugs 16 was measured, and the percentage of adhering mud was calculated. And the evaluation in the pneumatic tire of a prior art example was set to 100, and the index used as relative evaluation was computed about the pneumatic tire of the Example. The evaluation results are shown in Table 2. Table 2 shows that the smaller the index, the higher the performance.

表２から判るように、実施例の空気入りタイヤでは、従来例の空気入りタイヤに比べ、大幅に良好な評価結果となっており、泥付着量を７０％程度減らすことができた。

As can be seen from Table 2, the pneumatic tires of the examples had significantly better evaluation results than the conventional pneumatic tires, and the mud adhesion amount could be reduced by about 70%.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Further, it goes without saying that the scope of rights of the present invention is not limited to these embodiments.

1 is a schematic perspective view of a pneumatic tire according to an embodiment of the present invention. It is a typical side sectional view of a vulcanization mold concerning one embodiment of the present invention. It is the elements on larger scale obtained by image | photographing the mold part surface of the vulcanization mold of an Example with a microscope. It is the elements on larger scale obtained by photographing the tread section of the pneumatic tire of an example with a microscope. Partial enlarged view obtained by photographing the mold surface of the vulcanization mold of the conventional example with a microscope It is the elements on larger scale obtained by photographing the tread section of the pneumatic tire of the conventional example with a microscope.

Explanation of symbols

10 Pneumatic tire 14S tread surface (tire tread surface)
22 Vulcanization mold 22S Side wall surface (tire side surface)
24 Mold part 24S Surface 30 Pneumatic tire 34S Tread surface (tire tread surface)
40S sidewall surface (tire side surface)
42 Vulcanization mold 44 Mold part 44S Surface

Claims (5)

  Using a vulcanized mold in which at least the surface of the mold part for molding the tire tread surface and the tire side surface is surface-treated by shot blasting with a blasting material having a particle size of 200 to 800 μm and a Mohs hardness of 3 to 7 A method for producing a pneumatic tire, characterized by vulcanization molding.   The method for producing a pneumatic tire according to claim 1, wherein the blast material is a glass-based or plastic-based blast material. A vulcanization mold used for vulcanizing a pneumatic tire,
The surface of the mold part for molding at least the tire tread surface and the tire side surface is surface-treated by shot blasting with a blasting material having a particle size in the range of 200 to 800 μm and a Mohs hardness of 3 to 7. Sulfur mold.   The method for producing a pneumatic tire according to claim 3, wherein the blast material is surface-treated with a glass-based or plastic-based blast material.   A pneumatic tire having a surface roughness of at least a tire tread surface and a tire side surface in a range of 80 to 300 μm and a surface wavelength of 1.5 times or more of the surface roughness.

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