JP2007230162A - Mold for vulcanizing/molding tire and pneumatic tire manufactured using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve productivity by preventing the adhesion between a mold and a tire that takes place upon opening the mold without using a mold release agent and the like and without an increased mold cost. <P>SOLUTION: In the side forming surfaces of molds 1, 2 for tire vulcanizing/molding which form a pair of tire sides, there is provided a region 12 which is different in at least one, out of surface hardness, surface material or surface roughness, from each other between one side forming surface and the other side forming surface, and the projection area on the tire equatorial face of the mutually different region 12 is ≥30% of the projection area on the tire equatorial face of the whole side forming surfaces. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tire vulcanization mold for vulcanization molding of a pneumatic tire, and more particularly to a tire vulcanization mold having improved release properties after vulcanization molding.

  In vulcanization molding of tires, vulcanization molding is performed with a mold called a sector mold that consists of a segment divided into a plurality of segments for vulcanization molding of the tread portion and a side plate for vulcanization molding of the sidewalls. There are many. First, the raw tire is placed on the lower side plate, the side part of the raw tire is sandwiched with the upper side plate, the segment is moved inward in the tire radial direction, the mold is closed, and the raw tire is vulcanized To do. For example, a mold disclosed in Patent Document 1 is known.

  In addition to the above-mentioned mold, a tire vulcanization mold called a two-piece mold comprising an upper mold and a lower mold having a split surface in the vicinity of the tire equatorial plane is also used. When a two-piece mold is used, the green tire is placed on the lower mold, the upper mold is placed on the lower mold, the mold is closed, and the green tire is vulcanized.

JP 2000-37728 A (FIG. 1)

  Even when any of the above molds is used, usually only the upper side plate (or the upper mold) moves upward to open the mold. At this time, an operation of lifting the tire by the mechanism of the vulcanization molding machine and taking out the tire from the mold is performed. However, the tire side part after vulcanization molding is in close contact with the lower side plate (or lower mold), the tire removal fails, and the tire is left on the lower side plate (or lower mold). May occur.

  More specifically, in order to take out the tire, the tire after vulcanization molding needs to remain at a predetermined position in the vulcanization molding machine. The mechanism design of the vulcanizing machine determines which side of the tire needs to be peeled off first. On the other hand, the side surface that must be peeled off in advance is not peeled off, and the other side surfaces are peeled off first. As a result, the tire does not stay in a predetermined position and the tire removal fails. Alternatively, when the force for removing the tire is smaller than the force required to peel the contact surface between the tire and the mold, the tire removal fails.

  Since the tire vulcanization molding operation is automated, the occurrence of such a problem is fatal, and a recovery operation is required every time it occurs, resulting in a decrease in productivity. Further, when the sensor of the vulcanizing machine breaks down, the unvulcanized tire is newly loaded with the tire remaining after vulcanization molding in the mold, and the mold is automatically closed. As a result, the mold is often damaged.

  In a tire vulcanization mold, a molding surface (side surface molding surface) for molding a tire side portion is generally an iron background. Since the rubber disposed on the iron surface and the side portion of the tire is easy to adhere, measures are taken such as applying a mold release agent mainly composed of silicon to the side portion molding surface.

  A mold release agent mainly composed of silicon may enter an interface between different types of rubber constituting the tire, and may cause product defects such as peeling of a portion that must be integrated. There are also concerns about an increase in production cost due to the application of a release agent and a decrease in productivity due to an increase in production cycle time.

  Therefore, the object of the present invention is to prevent the adhesion between the mold and the tire, which occurs when the mold is opened, without using a mold release agent or the like and without increasing the mold cost. It is to improve the performance.

As a result of intensive studies to solve the above-mentioned problems, the present invention relates to a mold for molding a tire vulcanization, in a side part molding surface of a mold for molding a pair of tire side parts,
Between one side part molding surface and the other side part molding surface, at least one of surface hardness, surface material or surface roughness is provided with different areas,
The tire vulcanization mold is characterized in that a projected area of the tire equatorial plane in the different regions is 30% or more of a projected area of the tire equatorial plane of the entire one side portion molding plane.

  According to the knowledge of the inventors, it has been found that the adhesion between the mold molding surface and the rubber after vulcanization differs depending on the surface roughness and surface material of the mold molding surface. That is, with respect to surface roughness, rubber adhesion tends to increase on a smoother molding surface. Further, it was found that the adhesiveness tends to be increased even on a rough molded surface having a surface roughness exceeding a certain value. In the case of a surface roughness of 10 to 70 μm, more preferably 10 to 30 μm, and preferably an irregular uneven surface, the adhesion between the molding surface and the rubber was significantly reduced.

  When the surface material is chrome, the molding surface and the rubber are difficult to adhere. On the other hand, when the surface material is copper, the molding surface and the rubber are easily adhered. As for the hardness, it was found that the higher the hardness of the mold molding surface, the more difficult it is to adhere to the rubber.

  Therefore, in the side part molding surface of the mold for molding the pair of tire side parts, at least one of surface hardness, surface material, or surface roughness between one side part molding surface and the other side part molding surface. In the case where two different regions are provided, there is a difference in adhesion between the two side part molding surfaces and the vulcanized rubber. The adhesiveness of the side part molding surface of the mold to be peeled off first from the tire can be relatively lowered. If the projected area of the tire equatorial plane in the different areas is 30% or more of the projected area of the tire equatorial plane of one entire side part molding surface, the adhesion between the side part molding surface of the mold and the rubber is sufficient. The difference can be provided. As a result, it is possible to prevent the above-described problems from occurring and improve productivity by preventing the mold side surface and the rubber from sticking to each other without using a mold release agent or the like.

The invention of the present application is a mold part for molding a tire vulcanization, in a side part molding surface of a mold for molding a pair of tire side parts,
Between one side part molding surface and the other side part molding surface, at least one of surface hardness, surface material or surface roughness is provided with different areas,
The tire equatorial plane projected area of the different region in the radially outer region outside the radial direction of the tire from the position where the tire width of the side portion molding surface is maximum is the tire equatorial plane projected area of the radially outer region. It is characterized by being 70% or more.

  In the invention of the present application, there is a character processing region where characters are raised on the tire side surface in the vicinity of the position where the tire width of the molding surface is maximum, and it is difficult to change the surface hardness, surface material or surface roughness. Sometimes. However, since the radially outer region located outside the tire radial direction from the position where the tire width is maximized is generally formed of a smooth curved surface having no irregularities in the tire circumferential direction, it is easy to change the surface hardness and the like. is there. The projected area of the tire equatorial plane in the different areas is 70% or more of the projected area of the tire equatorial plane in the radially outer area, thereby providing a sufficient difference in adhesion between the side surface of the mold and the rubber. be able to.

  The present invention relates to an unevenness in which a thin film different from the mold base material is formed on at least one surface of the different regions, the surface hardness is different from each other, and the surface roughness of at least one of the different regions is 10 to 70 μm. It is a surface.

  By forming a thin film different from the mold base material (often iron) on the surface of the side portion molding surface, the surface hardness and / or surface material can be varied. Further, if the side portion molding surface is an uneven surface having a surface roughness of 10 to 70 μm, the adhesion to the rubber is further lowered, and a difference in adhesion between the side portion molding surface of the mold and the rubber is provided. be able to.

The invention of the present application is a mold part for molding a tire vulcanization, in a side part molding surface of a mold for molding a pair of tire side parts,
Between one side part molding surface and the other side part molding surface, at least one of surface hardness, surface material or surface roughness is provided with different areas,
The tire equatorial plane projected area of the different region in the radially inner region located on the inner side in the tire radial direction from the character processing region of the side portion molding surface is 70% or more of the tire equatorial plane projected area of the radially inner region. There,
A thin film different from the mold base material is formed on at least one surface of the different regions, the surface hardness is different from each other, and the surface roughness of at least one of the different regions is 10 to 70 μm. It is characterized by.

  As described above, since processing is easy in the tire radial direction inner region than the character processing region, the different regions in the radial inner region located on the inner side in the tire radial direction from the character processing region of the side portion molding surface. The projected area of the tire equatorial plane is 70% or more of the projected area of the tire equatorial plane in the radially inner region, and in a different region, a thin film different from the mold base material is formed, so that the surface hardness and / or By making the surface material different and further making the side portion molding surface an uneven surface with a surface roughness of 10 to 70 μm, the adhesiveness with the rubber is further reduced, and the side portion molding surface of the mold and the rubber A difference in adhesion can be provided. In the present application, the character processing region means a region of a mold forming surface where a character that can be read even when the tire is mounted on the rim, and excludes a region where a character hidden by the rim is formed.

  The present invention is characterized in that the thin film is formed by any one of plating, thermal spraying, vapor deposition, and baking.

  A known method may be used to vary the surface material and the surface hardness, but any one of plating, thermal spraying, vapor deposition, and baking can be processed at low cost.

  Hereinafter, embodiments of a tire vulcanization mold according to the present invention will be described with reference to the drawings. Fig.1 (a) shows sectional drawing of the metal mold | die for tire vulcanization molding which concerns on this invention, and shows the state which the metal mold | die closed. This is a sector mold type mold, and the tire side portion of the green tire G is sandwiched between the upper side plate 1 and the lower side plate 2, and then the segment 3 divided in the tire circumferential direction is reduced in diameter to close the mold. . In the figure, a mechanism for opening and closing the mold and a mechanism for holding the raw tire from the inside (for example, a bladder) are omitted, but a known mechanism can be used.

  After the tire vulcanization, the segment 3 first expands, and then only the upper side plate 1 moves upward to open the mold. At this time, an operation of lifting the tire by a mechanism (not shown) of the vulcanization molding machine and taking out the tire from the mold is performed. Therefore, it is a metal mold | die which performs the operation | movement which peels with the upper side plate 1 and a tire previously.

  FIG. 1B is a diagram in which the side portion molding surface of the upper side plate 1 is projected onto the tire equatorial plane C. FIG. The side portion molding surface has an annular first region 11 and second region 12. The tire equatorial plane projected area of the second region 12 is 30% or more of the tire equatorial plane projected area of the entire side portion molding surface of the upper side plate 1. In the first region 11, the surface hardness, the surface material, or the surface roughness is the same as that of the lower side plate 2. The second region 12 is a region in which at least one of surface hardness, surface material, or surface roughness is different from the lower side plate 2.

  For example, by subjecting the second region 12 to a quenching treatment, the surface hardness increases, and the adhesion between the second region 12 and the rubber decreases. As a result, since the upper side plate 1 begins to peel first, manufacturing defects do not occur. It is also possible to insert an annular metal into the second region 12 so that the surface hardness and the surface material are different from each other. As described above, when only the surface hardness and surface material of the second region 12 are different from those of the first region 11 and the side plate 2, the surface roughness of the side portion molding surfaces of the upper side plate 1 and the side plate 2 is the same. Therefore, there is no difference in the appearance quality of the molded tire.

  Further, after the powder is sprayed onto the second region 12 and, if necessary, the corresponding region (not shown) of the other side portion molding surface to form irregular irregular surfaces on the surface, the second region 12 is formed. Alternatively, it is possible to form a thin film on the surface of any one of the corresponding regions and make the surface hardness and the surface material different from each other. The thickness of the thin film is preferably 10 to 30 μm, and the edge of the turning mark applied to the molding surface disappears, and effects such as crack prevention can be exhibited. The thin film may be formed by any one of plating, thermal spraying, vapor deposition, and baking by a known method.

  More specifically, by performing shot blasting in the second region 12, forming irregular irregular surfaces (surface roughness 20 μm), further applying chrome plating to the second region 12, and forming a thin film, Adhesiveness with the rubber of the upper side plate 1 can be reduced.

  As another example, irregularities are formed on the surface of the side portion molding surface by spraying a powder having a Mohs hardness lower than the hardness of the side portion molding surface to the second region 12 with compressed air, thereby reducing the surface roughness. It can be different from the first region 11 and the side plate 2.

  The surface roughness of the side part molding surface is preferably 10 to 70 μm. When the surface roughness is less than 10 μm or more than 70 μm, the adhesion between the side portion molding surface and the rubber becomes high. Here, the surface roughness means the maximum height roughness Rz defined by JIS B0601 (2001 edition), and is measured by a stylus having a tip radius of 5 μm by a measuring method according to JIS B0651 (1996 edition).

  Also, there is a character processing area in the tire side surface near the position where the tire width of the side portion molding surface is maximized, so that it is difficult to vary the surface hardness etc. In the radially outer region located on the outer side in the tire radial direction from the position where the tire width of the side portion molding surface of the plate 1 is maximized, the tire equatorial plane projection area of the second region 12 is the tire equator projection of the radially outer region. The area is preferably 70% or more of the area.

  Alternatively, in the radially inner region located on the inner side in the tire radial direction from the character processing region of the side portion molding surface, as described above, after forming irregular irregular surfaces on the surface of the second region 12, the mold base material and It is also possible to form different thin films with different surface hardness and surface material. In this case, it is preferable that the projected area of the tire equatorial plane in different areas be 70% or more of the area of the radially inner area.

  In the above description, the side portion molding surface for molding the side portion of the tire is annularly divided and the inner annular region is defined as the second region 12, but the outer annular region may be the second region 12. In addition to the method of dividing the ring, the second area 12 may be divided into small areas as shown in FIG. In the figure, the small area is circular, but is not limited thereto. Further, as shown in FIG. 2B, the second region 12 may be divided into a fan shape as shown in FIG. In any case, the sum of the tire equatorial plane projected areas of the second region 12 may be 30% or more of the tire equatorial plane projected area of the entire side portion molding surface.

  In the present application, the term “tire side portion” refers to the end of a concavo-convex portion having a height of 1 mm or more that extends in the tire radial direction from the tire ground contact edge, continues to a tread pattern (tread surface design), or is formed independently of the tread pattern. The tire size is displayed in more detail, from the part where the tire bead is fitted to the rim, from the part where the region without the uneven part continuous in the tire circumferential direction starts to the inside in the tire radial direction. This refers to a region up to the circumference having a diameter of a distance (for example, 381 mm for 15 inches) converted to millimeters. In addition, when the unevenness which forms a shallow line such as knurling processing and serrated processing is constructed on the molding surface of the side part, in addition to the unevenness, the unevenness which molds the tire brand etc. may also be constructed. is there. In this case, a region from a portion where the unevenness for knurling / serrated processing ends to a circumference having a diameter converted to millimeters as a rim diameter display is defined as a tire side portion.

  However, it can be processed so that at least one of the surface hardness, the surface material, and the surface roughness is different from each other regardless of the unevenness. Further, in a general mold, a mold for forming a tread pattern is made of aluminum, and a mold for molding a tire side part and a bead part is made of a steel material that is integrally or divided into a plurality of parts. Therefore, a tire side part is good also as an area | region shape | molded by the metal mold | die manufactured with the steel material.

  Even in the case of the two-piece mold including the upper mold 21 and the lower mold 22 shown in FIG. 3, the side part is formed by performing the above-described processing on the side part molding surface for molding the tire side part of the upper mold 21. The adhesion between the molding surface and the rubber is remarkably lowered, and the above-described effects are exhibited. In this case, the side portion molding surface refers to a molding surface for molding the tire side portion defined above.

1A is a cross-sectional view of a tire vulcanization molding die according to the present invention, and FIG. 1B is a diagram in which a molding surface of a side plate is projected onto a tire equatorial plane. FIGS. 2A and 2B are diagrams showing a form of division of the first area and the second area. FIG. 3 is a diagram showing an embodiment in a two-piece mold.

Explanation of symbols

1 Upper side plate 2 Lower side plate 3 Segment 11 First region 12 Second region 21 Upper die 22 Lower die

Claims (6)

In the mold part for tire vulcanization molding, on the side part molding surface of the mold for molding a pair of tire side parts,
Between one side part molding surface and the other side part molding surface, at least one of surface hardness, surface material or surface roughness is provided with different areas,
The tire vulcanization molding die, wherein the tire equatorial plane projected areas of the different regions are 30% or more of the tire equatorial plane projected area of the entire one side portion molding surface. In the mold part for tire vulcanization molding, on the side part molding surface of the mold for molding a pair of tire side parts,
Between one side part molding surface and the other side part molding surface, at least one of surface hardness, surface material or surface roughness is provided with different areas,
The tire equatorial plane projected area of the different region in the radially outer region outside the radial direction of the tire from the position where the tire width of the side portion molding surface is maximum is the tire equatorial plane projected area of the radially outer region. A mold for tire vulcanization molding characterized by being 70% or more.   A concavo-convex surface in which a thin film different from a mold base material is formed on at least one surface of the different regions, the surface hardness is different from each other, and the surface roughness of at least one of the different regions is 10 to 70 μm. Item 3. A mold for tire vulcanization molding according to Item 1 or 2. In the mold part for tire vulcanization molding, on the side part molding surface of the mold for molding a pair of tire side parts,
Between one side part molding surface and the other side part molding surface, at least one of surface hardness, surface material or surface roughness is provided with different areas,
The tire equatorial plane projected area of the different region in the radially inner region located on the inner side in the tire radial direction from the character processing region of the side portion molding surface is 70% or more of the tire equatorial plane projected area of the radially inner region. There,
A thin film different from the mold base material is formed on at least one surface of the different regions, the surface hardness is different from each other, and the surface roughness of at least one of the different regions is 10 to 70 μm. Die for tire vulcanization molding.   The tire vulcanization mold according to claim 3 or 4, wherein the thin film is formed by any one of plating, thermal spraying, vapor deposition, and baking.   A pneumatic tire manufactured by the tire vulcanization mold according to any one of claims 1 to 5.

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