JP2007001076A - Tire mold, its manufacturing method and tire manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire mold capable of suppressing the occurrence of the spew of a tire and capable of forcibly discharging the air in the tire mold to the outside of the tire, its manufacturing method and a tire manufacturing method. <P>SOLUTION: In the tire mold 1 equipped with projections 2 for forming grooves to the tread part of the tire, the recessed parts 3 for forming the surface of the tread part and the through-holes 4 formed to the projections, the through-holes 4 are formed into the shape piercing through the projections 2 in a plate form and an exhaust hole 9 allowed to pierce through the through-holes 4 and the external surface 8 of the tire mold 1 is formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tire mold used for vulcanization molding of a tire, a manufacturing method thereof, and a manufacturing method of a tire using the tire mold.

2. Description of the Related Art A tire mold (tire mold) is known in which a protrusion for forming a groove in a tread portion of a tire has a through-hole having a circular cross section called a cross vent hole. The diameter of the through hole circle is 0.8 mm to 1.0 mm. A tire mold having an exhaust hole called a vent hole that penetrates a recess for forming the surface of a tread portion of the tire and an outer surface of the tire mold is known (see, for example, Patent Document 2). .
JP-A-2-14109 JP-A-7-24843 JP 2002-67042 A

  When vulcanizing a tire using the tire mold, rubber flows into the through hole and solidifies, so that a rubber protrusion called a spew is formed in the groove of the tire tread after completion. . Further, the rubber that has flowed into the through hole is cut and clogged in the exhaust hole, which may cause an air retention defect (bear) during tire vulcanization.

The tire mold of the present invention is a tire mold comprising a protrusion for forming a groove in a tread portion of a tire, a recess for forming a surface of the tread portion, and a through hole formed in the protrusion. Is formed in a shape penetrating the protrusion in a plate shape, and an exhaust hole is formed through the through hole and the outer surface of the tire mold. The hole width corresponding to the plate-like thickness direction of the through hole is 10 μm to 100 μm, or the through hole is formed to extend in a direction along a plane perpendicular to or inclined with respect to the surface of the recess. In addition, a plurality of through holes are formed extending in the direction along the surface of the recess, and a plurality of through holes are formed at predetermined intervals along a direction corresponding to the direction along the circumferential surface of the tire at the protrusion. And the distance between the bottom surface of the recess for forming the surface of the tread portion and the through hole is less than 0.5 mm.
The method for manufacturing a tire mold of the present invention is such that a plate for forming a through-hole is installed in a portion where a projection is formed in a mold, and then the cast metal is poured into the mold and cast, and then the plate is removed from the projection. Thus, a through hole is formed. After the plate for forming the through hole is installed in the part where the projection is formed in the mold and the hole forming body for forming the exhaust hole is connected to the plate, the casting metal is poured into the mold and cast. It is also characterized in that the hole forming body is removed to form an exhaust hole and the plate is removed from the protrusion to form a through hole.
In the tire manufacturing method of the present invention, when a tire is vulcanized by a tire mold, the air is sucked from the outside of the tire mold through the exhaust hole, and the air in the tire mold is taken out of the tire mold through the through hole and the exhaust hole. It is characterized by being exhausted.

According to the tire mold of the present invention, the through hole is formed in a shape penetrating the protrusion in a plate shape, and the exhaust hole is formed through the through hole and the outer surface of the tire mold. By reducing the width, it is possible to reduce the formation of spew due to the rubber flowing into the through-hole and the clogging of the exhaust hole due to the rubber flowing into the through-hole being cut. Therefore, a tire with less spew can be obtained. Further, since the air in the tire mold can be forcibly exhausted to the outside of the tire mold through the through holes and the exhaust holes, it is possible to reduce the shape defect of the tire final product caused by the air trapping failure at the time of tire vulcanization. In particular, when the hole width of the through hole is 10 μm to 100 μm, spew formation and clogging of the exhaust hole due to rubber can be effectively prevented. By forming the through-hole in a direction along a surface orthogonal to or inclined with respect to the surface of the recess, or extending in a direction along the surface of the recess, the circumferential surface of the tire at the protrusion A plurality of through holes can be formed at predetermined intervals along a direction corresponding to the direction along the direction along which the spew is formed and the air pockets are formed over the entire circumferential surface of the tire. Defects can be prevented. By setting the distance between the bottom surface of the recess and the through hole for forming the surface of the tread portion to be less than 0.5 mm, air that tends to collect around the boundary between the projection and the recess is formed during vulcanization of the tire. It can exhaust effectively.
According to the method for manufacturing a tire mold of the present invention, it is possible to obtain a tire mold that can suppress the occurrence of tire spew and a tire mold that can forcibly exhaust the air in the tire mold to the outside of the tire mold.
According to the tire manufacturing method of the present invention, it is possible to obtain a tire with less spew and shape defects.

Form 1
FIG. 1 shows a tire mold according to embodiment 1, and FIG. 2 (a) is a portion where a through hole is located along a direction orthogonal to a direction along a direction A (see FIG. 1) in which the tire mold extends. FIG. 2 (b) shows a cross section when the tire mold is cut along the direction A in which the protrusion extends, including the protrusion and the through hole, and FIG. 3 (a). FIG. 3 (b) shows a tire mold manufacturing method.

  As shown in FIG. 1, the tire mold 1 has a protrusion 2 and a recess 3 formed in a portion for transferring and forming a tread portion of the tire. The protrusion 2 is a portion for forming a groove (tread pattern groove) in the tread portion of the tire, and the concave portion 3 is a portion for forming the surface of the tread portion of the tire. The protrusion 2 is formed with a through hole 4 called a cross vent hole that penetrates the two recesses 3; 3 separated by the protrusion 2. The side wall 5 on the inner surface of the through hole 4 has the same shape as the cut surface when the protrusion 2 is cut along a direction orthogonal to the direction A along which the protrusion 2 extends. The thickness of the through hole 4 in the direction along the direction A in which the protrusion 2 extends, that is, the shortest distance of the distance D (see FIG. 2B) between both side walls 5; 5 of the inner surface of the through hole 4 It is formed in the range of 10 μm to 100 μm. That is, the through-hole 4 is formed in a shape penetrating the protrusion 2 in a plate shape, and the hole width D (= interval D) corresponding to the plate-like thickness direction of the through-hole 4 is in the range of 10 μm to 100 μm. Formed. The through hole 4 is formed in the protrusion 2 in the vicinity of the corner 11 of the recess 3. The bottom surface 6 of the through hole 4 and the bottom surface 7 of the recess 3 are preferably formed on the same surface. That is, the distance Z (not shown) between the bottom surface 7 of the recess 3 and the bottom surface 7 of the through hole 4 is preferably 0 mm or as close as possible to 0 mm. That is, when the tire is vulcanized, air easily collects around the boundary between the protrusion 2 and the recess 3, and the distance Z is optimally set to 0 mm in order to effectively remove the air. Since the distance Z between the through hole of a round hole called a conventional cross vent hole and the mold surface layer (corresponding to the recess 3) is 0.5 mm or more (0.5 mm to 0.6 mm), in the first embodiment, the distance Z By setting this to at least less than 5 mm, it is possible to effectively prevent air accumulation defects during vulcanization of the tire. The tire mold 1 is formed with an exhaust hole 9 called a vent hole that penetrates the through hole 4 and the outer surface 8 of the tire mold 1. The hole diameter D1 of the exhaust hole 9 is preferably larger than the hole width D of the through hole 4. The through hole 4 extends from the bottom surface 7 of one of the two recesses 3; 3 separated by the projection 2 to the bottom surface 7 of the other recess 3 via the peripheral surface 2 a of the projection 2. It has a groove (slit) shape in which the linear opening 10 with the interval D is connected to the exhaust hole 9. For example, 50 to 100 through-holes 4 are formed at predetermined intervals along a direction corresponding to the direction along the circumferential surface of the tire in the protrusion 2. For example, by setting the predetermined interval to an interval corresponding to the pitch of the tread pattern of the tire manufactured by the tire mold 1, it is possible to prevent spew formation and air accumulation defects over the entire peripheral surface of the tire.

  With reference to FIG. 3, the manufacturing method of the tire mold 1 is demonstrated. As shown in FIG. 3A, a plate 15 having a constant thickness in the range of 10 μm to 100 μm is previously installed in the gypsum mold 20. In the lower mold 21 of the mold 20, the molding space 16 of the projection 2 is cut along a direction perpendicular to the direction A (see FIG. 1) in which the projection 2 extends to the outside of the molding space 16. An extending groove (slit) 17 is formed. The thickness of the groove 17 is a constant thickness in the range of 10 μm to 100 μm. By inserting the plate 15 into the groove 17, the plate 15 is installed on the lower mold 21 of the mold 20. The upper end edge surface 17a of the groove 17 and the upper surface 15a of the plate 15 are set at the same height. The upper mold 22 of the mold 20 is provided with a hole forming body 18 such as a round bar for forming an exhaust hole 9 that penetrates the through hole 4 and the outer surface 8 of the tire mold 1. After placing the upper mold 22 on the lower mold 21 so that the lower end surface 18a of the hole forming body 18 and the upper surface 15a of the plate 15 are in contact with each other, casting is performed in a molding space 16; 19 formed by combining the mold 20 After casting a molten aluminum alloy as a metal, the upper mold 22 and the lower mold 21 of the mold 20 are released, so that an intermediate product in which the exhaust holes 9 are formed as shown in FIG. Get 25. Thereafter, the plate 15 is pulled out from the protrusion 2 in the direction of the arrow F1. As described above, as shown in FIG. 1, the through hole 4 formed in a shape penetrating the protrusion 2 in a plate shape, and the exhaust hole 9 penetrating the through hole 4 and the outer surface 8 of the tire mold 1 are formed. The provided tire mold 1 can be obtained.

  A tire manufacturing method will be described. When the tire is vulcanized by the tire mold 1, it is sucked from the outside of the tire mold 1 through the exhaust hole 9 by a vacuum outside the figure and penetrates the air in the tire mold 1 as indicated by an arrow B in FIG. By exhausting to the outside of the tire mold 1 through the holes 4 and the exhaust holes 9, a tire with less spew and shape defects can be obtained.

  According to the tire mold 1 of the first aspect, the protruding portion 2 includes the through hole 4, and the through hole 4 is formed in a shape penetrating the protruding portion 2 in a plate shape, and the through hole 4 and the outer surface 8 of the tire mold 1. Since the exhaust hole 9 is formed and the hole width D of the through hole 4 is set in the range of 10 μm to 100 μm, rubber flows into the through hole 4 during tire vulcanization. Even if the rubber does not protrude (or protrudes) or the rubber flows into the through-hole 4 (even if it protrudes), the amount can be made minute, and the formation of spew and clogging of the exhaust hole 9 due to rubber can be effectively prevented. . Therefore, a tire with less spew can be obtained. Further, since the air in the tire mold 1 can be forcibly exhausted to the outside of the tire mold through the through holes 4 and the exhaust holes 9, the shape of the final tire product caused by poor air retention during tire vulcanization is reduced. it can. On the other hand, as in the conventional case, in a through hole called a cross vent hole having a circle diameter of 0.8 mm to 1.0 mm, rubber easily flows into the through hole, and spew is easily formed. In addition, there is a problem that the rubber flowing into the through hole is cut and clogged in the exhaust hole. If the exhaust hole is clogged with rubber, the air in the tire mold cannot be forcibly exhausted through the through hole and the exhaust hole, resulting in a defective shape of the final tire product caused by a poor air retention during tire vulcanization. On the other hand, according to the tire mold 1 of the form 1, spew formation and clogging of the exhaust holes 9 due to rubber can be effectively prevented, and the air in the tire mold 1 is forced through the through holes 4 and the exhaust holes 9. Can exhaust. The through-hole 4 has a shape penetrating the protrusion 2 in a plate shape, and in particular, an interval extending to the bottom surface 7 of the other recess 3 via the peripheral surface 2a of the protrusion 2 during tire vulcanization. Since the straight opening 10 of D is a slit shape that connects the inside of the tire mold 1 and the exhaust hole 9, the opening 10 that connects the inside of the tire mold 1 and the exhaust hole 9 is long and passes through the opening 10. Thus, the rubber does not easily flow into the inside, and therefore the rubber is not easily cut. On the other hand, since a conventional through hole having a diameter of 0.8 mm to 1.0 mm has one circular opening having a diameter of 0.8 mm to 1.0 mm, rubber easily flows into the inside from this one opening. This structure is easy to cut and easily causes rubber clogging of the exhaust hole.

Form 2
FIG. 4 shows a part of the tire mold according to mode 2, and FIG. 5 (a) shows the position of the through hole along the direction orthogonal to the direction along the direction A (see FIG. 1) in which the tire mold extends. FIG. 5B shows a cross section when the tire mold is cut along the direction A in which the protrusions extend, including the protrusions and through holes, and FIG. (A) thru | or FIG.6 (c) show the manufacturing method of a tire mold.

  As shown in FIG. 4, a through hole 4 </ b> A called a cross vent hole is formed in the protrusion 2 of the tire mold 1 </ b> A of form 2 and penetrates the two recesses 3; 3 separated by the protrusion 2. The through hole 4A is formed in a shape that penetrates the protrusion 2 in a plate shape. A hole width D (= interval D) corresponding to the plate-like thickness direction of the through-hole 4A is formed within a range of 10 μm to 100 μm. The through hole 4 </ b> A is formed in the protrusion 2 in the vicinity of the corner 11 of the recess 3. The through hole 4 </ b> A is preferably formed such that one inner surface 6 </ b> A orthogonal to the hole width D is in contact with the bottom surface 7 of the recess 3 along the direction A along which the protrusion 2 extends. That is, the distance Z (not shown) between the bottom surface 7 of the recess 3 and the bottom surface 7 of the through hole 4 is set to 0 mm so that the bottom surface 7 of the recess 3 and the inner surface 6A of the through hole are continuous and the same surface. The distance Z is preferably as close as possible to 0 mm. When the tire is vulcanized, air tends to accumulate around the boundary between the projection 2 and the recess 3, and the distance Z is optimally set to 0 mm in order to effectively remove the air. In the second aspect, by setting the distance Z to be at least less than 5 mm, it is possible to effectively prevent an air retention failure during vulcanization of the tire. In the tire mold 1A, an exhaust hole 9A called a vent hole is formed through the through hole 4 and the outer surface 8 of the tire mold 1A. The hole diameter D2 of the exhaust hole 9A is larger than the hole width D of the through hole 4A. The exhaust hole 9A is connected to the center position of the inner surface 6A of the through hole 4A. Therefore, the air inside the tire mold 1A can be exhausted to the outside of the tire mold 1 through the opening 10A of the through hole 4A, the through hole 4A, and the exhaust hole 9A. For example, 50 to 100 through holes 4A are formed at a predetermined interval along a direction corresponding to the direction along the circumferential surface of the tire in the protrusion 2. For example, by setting the predetermined interval to an interval corresponding to the pitch of the tread pattern of a tire manufactured with the tire mold 1A, spew formation and air accumulation failure can be prevented over the entire peripheral surface of the tire. The width W in the direction orthogonal to the hole width D in the through hole 4A is in the range of 5 mm to 20 mm.

  A method for manufacturing the tire mold 1A will be described. First, a wooden mold as a base of a mold is prepared, and rubber is poured into the wooden mold to form a rubber mold. Next, after a plate is inserted and set in a predetermined position of the rubber mold, gypsum is poured into the rubber mold to create a gypsum mold. At this time, the plate moves from the rubber mold to the gypsum mold and is stuck in the gypsum mold. Then, aluminum is poured into the plaster mold to create an aluminum mold. At this time, the plate moves from the gypsum mold to the aluminum mold. And a through-hole is formed by extracting a board from an aluminum metal mold | die. The case where the through hole 4A of the tire mold 1 of FIG. 4 is formed will be described with reference to FIG. As shown in FIG. 6 (a), in the rubber mold 40 formed by pouring rubber into a wooden mold not shown in the figure, from both ends of the position corresponding to the lower surface of the protrusion 2, a constant range of 10 μm to 100 μm is obtained. 15B1; 15B2 formed by dividing the thick plate 15 into two parts are inserted and installed. There may or may not be a gap between the plate 15B1 and the plate 15B2. Gypsum is poured into the rubber mold 40 on which the plate 15B is installed to create a gypsum mold. At this time, as shown in FIG. 6B, the plate 15 </ b> B moves from the rubber mold 40 to the gypsum mold 41 and is stuck in the gypsum mold 41. Next, aluminum is poured into the gypsum mold 41 to create an aluminum mold. At this time, the plate 15B moves from the gypsum mold 41 to the aluminum mold 42 as shown in FIG. Then, the through-hole 4A is formed by extracting the plate 15B from the aluminum mold 42. And exhaust hole 9A which connects the outer surface 8 of the aluminum metal mold | die 42 used as the tire mold 1A, and the through-hole 4A is formed using drills, such as a drill outside a figure. As described above, as shown in FIG. 4, the through-hole 4A formed in a shape penetrating the protrusion 2 in a plate shape, and the exhaust hole 9A penetrating the through-hole 4 and the outer surface 8 of the tire mold 1A. The provided tire mold 1A is obtained. According to the tire mold 1A, the same effect as that of the tire mold 1 according to the first aspect is obtained. According to the manufacturing method of the tire mold 1A, the processing for the gypsum mold 41 for installing the plate for forming the through-hole 4A in the gypsum mold 41 can be eliminated. Work can be eliminated.

  The plates 15; 15A; 15B for forming the through holes are made of a material having a melting point higher than that of aluminum. For example, a plate made of stainless steel or iron is used.

  By setting the hole width D of the through hole 4; 4A to a value close to the range of 10 μm to 100 μm, even if it is not in the range of 10 μm to 100 μm, rubber does not flow into the through hole 4; 4A during tire vulcanization. Even if the rubber flows into the through-hole 4; 4A (even if it protrudes), the amount can be made very small, and it is effective for spew formation and clogging of the exhaust hole 9; 9A due to rubber. Can be prevented. In the first aspect, the tire mold 1 including the through hole 4 extending in the direction along the surface orthogonal to the surface of the recess 3 is shown. However, the penetration extending in the direction along the surface inclined with respect to the surface of the recess 3 is shown. The tire mold 1 having the holes 4 may be used.

The perspective view which shows the tire mold of the form 1 of this invention. FIG. 2A is a cross-sectional view of the tire mold of form 1 cut at a portion where a through hole is located along a direction perpendicular to the direction along which the protrusion extends, and FIG. Sectional drawing at the time of cut | disconnecting the part of a protrusion part and a through-hole along the direction where a protrusion part is extended of 1 tire mold. The figure which shows the manufacturing method of the tire mold of the form 1. The perspective view which shows the tire mold of the form 2 of this invention. FIG. 5A is a cross-sectional view of the tire mold of form 2 cut at a portion where the through hole is located along a direction orthogonal to the direction along which the protrusion extends, and FIG. 5B is the form. Sectional drawing at the time of cut | disconnecting the tire mold of 2 including a protrusion part and the part of a through-hole along the direction where a protrusion part extends. The figure which shows the manufacturing method of the tire mold of the form 2.

Explanation of symbols

1; 1A tire mold, 2 protrusion, 3 recess, 4; 4A through-hole,
7 bottom surface of recess, 8 outer surface of tire mold, 9; 9A exhaust hole,
15; 15A; 15B plate, 18; 18A hole former, 20; 20A mold, D hole width.

Claims (9)

  In a tire mold having a protrusion for forming a groove in a tread portion of a tire, a recess for forming a surface of the tread portion, and a through hole formed in the protrusion, the through hole forms a plate-like protrusion. A tire mold having an exhaust hole formed in a penetrating shape and penetrating the through hole and an outer surface of the tire mold.   2. The tire mold according to claim 1, wherein a hole width corresponding to a plate-like thickness direction of the through hole is 10 μm to 100 μm.   The tire mold according to claim 1 or 2, wherein the through hole is formed to extend in a direction along a surface orthogonal to or inclined with respect to the surface of the recess.   The tire mold according to claim 1 or 2, wherein the through hole is formed to extend in a direction along the surface of the recess.   The tire according to any one of claims 1 to 4, wherein a plurality of through holes are formed at a predetermined interval along a direction corresponding to a direction along the circumferential surface of the tire in the protruding portion. mold.   The tire mold according to any one of claims 1 to 5, wherein a distance between the bottom surface of the recess for forming the surface of the tread portion and the through hole is less than 0.5 mm.   The method for manufacturing a tire mold according to any one of claims 1 to 6, wherein a plate for forming a through hole is installed in a portion where a projection is formed in a mold, and then a molten metal of cast metal in the mold A method of manufacturing a tire mold, wherein a through hole is formed by removing the plate from the protrusion after casting and casting.   8. The method for manufacturing a tire mold according to claim 7, wherein a plate for forming a through hole is installed in a portion of the mold where the protrusion is formed and a hole forming body for forming an exhaust hole is connected to the plate. Then, after casting the molten metal of the cast metal into the mold and casting, the hole forming body is removed to form the exhaust hole, and the plate is removed from the projection to form the through hole. Method.   A tire manufacturing method using the tire mold according to any one of claims 1 to 6 or the tire mold manufactured by the tire mold manufacturing method according to claim 8, wherein the tire is vulcanized by the tire mold. A method for manufacturing a tire characterized in that, sometimes, air is sucked from the outside of a tire mold through an exhaust hole, and air in the tire mold is exhausted to the outside of the tire mold through a through hole and an exhaust hole.

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