JP4169570B2 - Tire mold and pneumatic tire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire mold and a pneumatic tire. More specifically, the present invention relates to a tire mold in which the number of gas vent passages such as vent holes is reduced to reduce the generation of spew and molding using the mold. Related to pneumatic tires.
[0002]
[Prior art]
The tire mold is provided with a number of venting passages such as vent holes for discharging the air remaining in the mold during tire vulcanization and the gas generated at that time to the outside of the mold. Yes. As a result, in the tire after vulcanization, a large amount of the rubber extruded into the gas vent passage becomes spew (a ridge-like protrusion) and remains on the tire surface.
[0003]
For this reason, an operation of cutting and removing spews is performed after the vulcanization is completed. However, since many spew cut traces remain on the tire surface, the appearance must be deteriorated. In addition, it takes time to cut and remove as much as there are spews, resulting in poor work efficiency. In addition, since the removed spew is disposed of as industrial waste, the material is wasted and the amount of spew is increased, leading to an increase in industrial waste.
[0004]
Therefore, in recent years, as a countermeasure, an annular groove for venting gas is formed along the circumferential direction on the side molding surface of the tire mold, and the air collected in the groove is discharged to the outside through the venting passage. There has been proposed a metal mold (for example, see Patent Document 1). By providing such a venting groove, the number of venting passages is greatly reduced, and the generation of spew is greatly reduced.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-166424 [0006]
[Problems to be solved by the invention]
However, in the above proposed mold, in order to effectively discharge the air collected in the annular groove to the outside, it is necessary to connect eight or more gas vent passages to the same groove, and there is room for further improvement. there were.
[0007]
An object of the present invention is to provide a tire mold and a pneumatic tire that can further reduce the generation of spew by further reducing the number of vent holes such as vent holes.
[0008]
[Means for Solving the Problems]
In the tire mold of the present invention that achieves the above object, a groove extending along the circumferential direction of the mold is provided on a side molding surface for molding the sidewall portion of the tire, and the groove depth is gradually increased. The gas vent passage is communicated with the deepest part of the groove.
[0009]
Another tire mold of the present invention is provided with a groove extending along the circumferential direction of the mold on the side molding surface for molding the sidewall portion of the tire, and the groove is configured such that the groove width becomes narrower sequentially, A gas vent passage is communicated with the narrowest portion of the groove.
[0010]
The pneumatic tire of the present invention has a protrusion having a width of 0.2 to 5.0 mm and a height of 0.1 to 5.0 mm extending along the tire circumferential direction on the outer surface of the sidewall portion. The protrusions are formed such that the protrusion heights are sequentially increased toward the highest part having the highest protrusion height, and a cut trace from which spew has been removed is present on the surface of the highest part .
[0011]
Another pneumatic tire of the present invention has a protrusion having a width of 0.2 to 5.0 mm and a height of 0.1 to 5.0 mm extending along the tire circumferential direction on the outer surface of the sidewall portion. The protrusions are formed such that the protrusion widths are gradually narrowed toward the narrowest part where the protrusion width is the narrowest, and there is a cutting trace on which the spew is removed on the surface of the narrowest part .
[0012]
According to the present invention described above, unvulcanized rubber having viscoelasticity that has flowed into the groove during tire vulcanization gathers the gas remaining in the groove and gas such as generated gas to the deepest part or the narrowest part. Since it can be gathered there and discharged to the outside through the gas vent passage, the number of gas vent passages can be further reduced as compared with the prior art to reduce the occurrence of spew. Therefore, the number of spew cuts can be reduced, the appearance can be improved, the spew cutting removal time can be reduced, the work efficiency can be improved, and the amount of spew to be removed can be reduced. In addition, the generation of industrial waste can be reduced.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0014]
FIG. 1 shows a sectional mold as an example of a tire mold according to the present invention. An annular upper mold 1 for molding one sidewall portion of a tire and an annular lower mold for molding the other sidewall portion. A mold 2 and an annular side mold 4 including a plurality of sectors 3 for forming a tread portion are provided.
[0015]
The upper mold 1 has side molding surfaces 5 and 6 for molding the sidewall portions on the lower surface side and the lower mold 2 on the upper surface side. The side mold 4 includes a tread molding surface 7 that molds a tread portion on the inner peripheral surface side.
[0016]
As shown in FIGS. 1 and 2, the side molding surfaces 5 and 6 are provided with annular grooves 8 and 9 extending along the mold circumferential direction F, respectively. Grooves 8 and 9 are provided for collecting and discharging gas remaining, such as air remaining during tire vulcanization and generated gas, to the outside. As shown in FIGS. The side portions 8a and 9a are the shallowest and the other side portions 8b and 9b are the deepest deepest portions, and the groove depth between them is continuously from the one side portions 8a and 9a toward the other side portions 8b and 9b. It is changing and getting deeper. The groove width of the grooves 8 and 9 is constant.
[0017]
One end of one vent hole (gas vent passage) 10, 11 communicates with the other side portions 8b, 9b which are the deepest portions of the grooves 8, 9. The vent holes 10 and 11 penetrate the upper mold 1 and the lower mold 2, and the other end is opened to the outside so that the gas collected at the deepest part of the grooves 8 and 9 can be discharged from the vent holes 10 and 11 to the outside. It has become. In FIG. 1, for easy understanding, the grooves 8 and 9 and the vent holes 10 and 11 are shown in an enlarged state for the sake of easy viewing.
[0018]
FIG. 4 shows an example of a pneumatic tire after removal of spew that has been vulcanized and molded using a tire mold having the grooves 8 and 9 described above. The tire T <b> 1 has an annular protrusion 32 that extends along the tire circumferential direction C on the outer surface 31 a of the sidewall portion 31. The protrusion 32 has a configuration in which the protrusion height is gradually increased while continuously changing the protrusion height from the one side 32a to the other side 32b. That is, the protrusion 32 has the highest portion having the highest protrusion height on the other side portion 32b, and the protrusion height continuously increases from the one side portion 32a toward the highest portion. The protrusion width of the protrusion 32 is constant. Only one cut mark 33 is left on the surface of the other side portion 32b from which the spew formed immediately after vulcanization is removed. Since the protrusion 32 is formed by the grooves 8 and 9, the width and height thereof are the same as the groove width and groove depth of the grooves 8 and 9 described later.
[0019]
Although not shown for the purpose of well-known, the pneumatic tire has a carcass layer mounted between the left and right bead portions 34 on the inner side of the tire, and tires around the bead cores whose both end portions are embedded in the bead portions 34. It is folded from the inside to the outside. A belt layer is provided on the outer peripheral side of the carcass layer of the tread portion 35. The same applies to the pneumatic tire shown in FIG. 9 below.
[0020]
The above-described grooves 8 and 9 show an example in which one groove is provided in each drawing, but usually 2 to 4 (plural) grooves are provided according to the size of the mold, that is, the tire size. One vent hole communicates with the deepest part of the groove.
[0021]
According to the tire mold of the present invention described above, gas such as residual air and generated gas gathers in the grooves 8 and 9 due to the rubber flow at the time of tire vulcanization, and is unvulcanized in the grooves 8 and 9. The rubber enters, and the unvulcanized rubber having viscoelasticity reaches the groove bottom from the one side 8a, 9a having the shallowest groove depth toward the other side 8b, 9b. Thus, since the grooves 8 and 9 are filled, the gas in the grooves 8 and 9 can be collected at the deepest portion of the grooves 8 and 9 and effectively discharged to the outside through the vent holes 10 and 11. Therefore, since it is only necessary to provide one vent hole 10 and 11 for each groove 8 and 9, the number of vent holes can be further reduced as compared with the conventionally proposed mold to greatly reduce the occurrence of spew. it can.
[0022]
As a result, spew cutting traces are reduced and the appearance can be improved. Further, the spew cutting and removing time can be reduced, work efficiency can be improved, and the amount of spew removed can be reduced, so that waste of materials can be reduced and industrial waste can be reduced.
[0023]
FIG. 5 shows another example of the gas discharge grooves 8 and 9 described above. Depending on the design formed on the sidewall portion of the tire, etc., the location where the gas tends to accumulate differs, and the gas exhaust groove may not be arranged in an annular shape depending on the design. It is a groove | channel provided in such a case, Comprising: The circular-arc-shaped groove | channel 14 partially extended along the circumferential direction is formed in the side molding surfaces 5 and 6. FIG. In FIG. 5, the side molding surface 6 of the lower mold 2 is schematically shown, but the side molding surface 5 of the upper mold 1 has the same configuration, so the figure is omitted, and numbers in parentheses are added to FIG. Is attached. The same applies to FIG. 6 described later.
[0024]
The groove 14 is formed so that the groove depth is the shallowest at one end (one side) 14a and the other end (the other side) 14b is the deepest deepest, and the above described from the one end 14a to the other end 14b. It is getting deeper as well. The groove width of the groove 14 is constant.
[0025]
One vent hole 15 communicates with the other end portion 14 b which is the deepest portion of the groove 14, and the gas collected at the deepest portion of the groove 14 can be discharged from the vent hole 15 to the outside. In this way, even in the groove 14 partially extending along the circumferential direction of the mold, the gas collected in the groove 14 is collected at the deepest portion of the groove 14, and is effective to the outside through the vent hole 15. Can be discharged, thereby reducing the number of vent holes and reducing spewing.
[0026]
FIG. 6 shows another example of the groove 14 described above. The groove 16 of FIG. 6 has the groove depth that is the shallowest at both ends 16a and 16b, and the central portion 16c is the deepest deepest portion. The depth of the groove gradually increases from the shallowest ends 16a, 16b to the deepest central portion 16c while continuously changing. The groove width of the groove 16 is constant.
[0027]
One vent hole 17 communicates with the central portion 16c, which is the deepest portion of the groove 16, so that the gas collected at the deepest portion of the groove 16 can be discharged from the vent hole 17 to the outside. Even if it is such a structure, the effect similar to the above can be acquired.
[0028]
In the embodiment described above, the groove depths of the grooves 8, 9, 14, and 16 are appropriately selected depending on the size of the mold, that is, the size of the tire to be molded, but are substantially 0.1 to 5.0 mm. It is better to change within this range. If the groove depth is less than 0.1 mm, it will be difficult for the unvulcanized rubber to smoothly flow into the groove during tire vulcanization, so the gas in the groove is effectively discharged to the outside through the vent hole. It becomes difficult. If it exceeds 5.0 mm, it is not preferable from the viewpoint of appearance.
[0029]
The groove widths of the grooves 8, 9, 14, and 16 are also appropriately selected depending on the size of the tire to be molded, and should be constant within a range of 0.2 to 5.0 mm. It is also possible to change the groove width to such an extent that the flow is not changed.
[0030]
The shape of the grooves 8, 9, 14, and 16 is not limited to the quadrangular cross section shown in the figure (see FIG. 1). For example, as shown in FIG. Yes, it is not particularly limited. The same applies to a groove 18 shown in FIG.
[0031]
The grooves 8, 9, 14, and 16 are preferably configured to continuously change the groove depth as described above, but the remaining gas such as air is collected from the shallowest part toward the deepest part. As long as the groove depth is changed sequentially so that it can be performed, for example, it may be changed stepwise. In the pneumatic tire formed with the mold having the grooves with the groove depths increasing in depth, the protrusions 32 formed on the outer surface 31a of the sidewall part 31 have the protrusion heights correspondingly higher. Become.
[0032]
FIG. 8 shows still another example of the gas discharge groove, and shows an example of the annular groove 18 with the groove width changed instead of the annular grooves 8 and 9 with the groove depth changed as described above. Is.
[0033]
The groove 18 has the narrowest groove width at one side 18a and the narrowest part at the other side 18b, and the groove width between them continuously changes from one side 18a to the other side 18b. However, it is getting narrower. The groove depth of the groove 18 is constant. One end of one vent hole 19 communicates with the other side portion 18b which is the narrowest portion of the groove 18 so that the gas collected in the narrowest portion of the groove 18 can be discharged to the outside from the vent hole 19.
[0034]
Even if the groove 18 has such a narrow groove width, the unvulcanized rubber having viscoelasticity at the time of vulcanization of the tire has the groove 18 from the one side portion 18a having the largest groove width toward the other side portion 18b having the smallest groove width. Since the gas in the groove 18 is collected in the narrowest part and can be effectively discharged to the outside through the vent hole 19, the number of vent holes is greatly reduced, and spew is generated. Can be greatly reduced.
[0035]
FIG. 9 shows an example of a pneumatic tire after removal of spew that has been vulcanized and formed using a tire mold having the groove 18 described above. The tire T2 has an annular protrusion 42 extending along the tire circumferential direction C on the outer surface 31a of the sidewall portion 31, while continuously changing the protrusion width from one side 42a to the other side 42b. The structure is gradually narrowed. That is, the protrusion 42 has the narrowest part where the protrusion width is the narrowest on the other side part 42b, and the protrusion width is continuously narrowed from the one side part 42a toward the narrowest part. The protrusion width of the protrusion 42 is constant. On the surface of the other side portion 42b, only one cut mark 43 is left after removing the spew formed immediately after vulcanization. Since the protrusion 42 is formed by the groove 18, the width and height thereof are the same as the groove width and groove depth of the groove 18 described later.
[0036]
The grooves 14 and 16 shown in FIGS. 5 and 6 can also have the groove width changed as described above, instead of the groove depth.
[0037]
As described above, the groove width of the groove 18 is appropriately selected according to the size of the mold, that is, the size of the tire to be molded, but can be substantially 0.2 to 5.0 mm, and its range. It is better to change within. If the groove width is shallower than 0.2 mm, it becomes difficult for the unvulcanized rubber to smoothly flow into the groove during tire vulcanization. Conversely, if it exceeds 5.0 mm, it is not preferable from the viewpoint of appearance.
[0038]
The groove depth of the groove 18 is also appropriately selected according to the size of the tire to be molded, but the groove depth is preferably constant within a range of 0.1 to 5.0 mm.
[0039]
It is preferable that the groove width of the groove 18 is continuously changed as described above, but the groove width is set so that the remaining gas such as air can be collected from the widest portion toward the narrowest portion. Any one may be used as long as it is changed sequentially. For example, it may be changed stepwise. Thus, in the pneumatic tire formed by the tire mold having the grooves whose groove widths are gradually reduced, the protrusions 42 formed on the outer surface 31a of the sidewall part 31 have protrusion heights corresponding to the corresponding protrusions. Get higher.
[0040]
In the present invention, in the above-described embodiment, an example of a sectional type tire mold is shown. However, the present invention may be a two-part type tire mold including an upper mold and a lower mold. Any mold having a side molding surface for molding the sidewall portion can be applied.
[0041]
Moreover, in the said embodiment, although the groove | channel for gas exhaustion mentioned above changed either the groove depth or the groove width, the groove | channel which changed both of them may be sufficient.
[0042]
【The invention's effect】
As described above, according to the present invention, a groove extending along the circumferential direction is provided on a side molding surface for molding a sidewall portion of a tire, and the groove depth is sequentially increased or the groove width is sequentially reduced. Since the gas vent passage is communicated with the deepest part or the narrowest part of the groove, the number of vent holes can be further reduced as compared with the conventionally proposed tire mold, and the generation of spew can be further reduced. . Therefore, it is possible to improve the appearance, increase the work efficiency of cutting and removing spew, reduce the waste of materials, and further reduce industrial waste.
[Brief description of the drawings]
FIG. 1 is a half sectional view showing an example of a tire mold according to the present invention.
2A is an explanatory diagram schematically showing an upper mold viewed from the lower side, and FIG. 2B is an explanatory diagram schematically showing the lower mold viewed from the upper side.
FIGS. 3A and 3B are expanded views showing a cross section of the groove in FIG. 2 cut along the center in the width direction, wherein FIG. 3A is an enlarged view showing an upper mold groove, and FIG. 3B is an enlarged view showing a lower mold groove; It is.
4 (a) is a schematic side view showing an example of a pneumatic tire molded using the tire mold of FIG. 1, and FIG. 4 (b) is an enlarged view showing a developed section cut along a protrusion. is there.
5A and 5B show another example of the groove, wherein FIG. 5A is an explanatory view schematically showing the lower mold viewed from above, and FIG. 5B is an enlarged view of the groove formed in the lower mold. It is an equivalent figure.
6 is a view corresponding to FIG. 5B showing another example of the groove in FIG. 5;
7A and 7B are enlarged cross-sectional views showing other shapes of grooves, respectively.
FIG. 8 is an explanatory view showing still another example of the groove, in a state where the annular groove viewed from the opening side is developed on a straight line over one circumference.
9A is a schematic side view showing an example of a pneumatic tire molded using a tire mold having a groove of FIG. 8 , and FIG. 9B is an enlarged view showing a protrusion.
[Explanation of symbols]
1 Upper mold 2 Lower mold 5, 6 Side molding surface 8, 9 Groove 8b, 9b The other side (deepest part)
10,11 Vent hole (gas vent passage)
14 Groove 14 b Other end (deepest part)
15 Vent hole (gas vent passage) 16 Groove 16c Center part (deepest part) 17 Vent hole (gas vent passage)
18 groove 18b other side (narrowest part)
19 Vent hole (gas vent passage) 31 Side wall 31a Outer surface 32, 42 Protrusion 33, 43 Cut trace C Tire circumferential direction F Mold circumferential direction T1, T2 Pneumatic tire

Claims (16)

A groove that extends along the circumferential direction of the mold is provided on a side molding surface that molds the sidewall portion of the tire, and the groove is configured so that the groove depth becomes deeper in order, and a gas vent passage is formed at the deepest portion of the groove. Tire molds that communicate with each other. 2. The tire mold according to claim 1, comprising annular upper and lower molds each having a side molding surface for molding a sidewall portion of the tire, wherein the groove is provided on a side molding surface of the upper and lower molds. The tire mold according to claim 1 or 2, wherein the groove depth is gradually deepened while continuously changing the groove depth. 4. The tire mold according to claim 1, wherein the groove depth is deepened from one side portion toward the other side portion, and the other side portion is the deepest portion. The tire mold according to claim 1, 2, 3, or 4, wherein the groove depth is 0.1 to 5.0 mm. The tire mold according to claim 1, 2, 3, 4, or 5, wherein the groove is an annular groove extending along a circumferential direction of the mold. A groove extending along the circumferential direction of the mold is provided on a side molding surface for molding the sidewall portion of the tire, and the groove is configured so that the groove width becomes narrower in order, and a gas vent passage is formed in the narrowest portion of the groove. Tire molds that communicate with each other. The tire mold according to claim 7, comprising annular upper and lower molds each having a side molding surface for molding a sidewall portion of the tire, wherein the groove is provided on a side molding surface of the upper and lower molds. The tire mold according to claim 7 or 8, wherein the groove width is gradually narrowed while continuously changing the groove width. The tire mold according to claim 7, 8 or 9, wherein the groove width is narrowed from one side portion toward the other side portion, and the other side portion is the narrowest portion. The tire mold according to claim 7, 8, 9, or 10, wherein the groove width is 0.2 to 5.0 mm. The tire mold according to claim 7, 8, 9, 10, or 11, wherein the groove is an annular groove extending along a circumferential direction. Extending along the outer surface of the sidewall portion in the tire circumferential direction, a width 0.2 to 5.0 mm, has a protrusion height 0.1 to 5.0 mm, the protrusion portion protruding height is most A pneumatic tire which is formed so that the height of the protrusions is gradually increased toward the highest highest portion, and the surface of the highest portion has a cut mark obtained by removing spew . The pneumatic tire according to claim 13, wherein the height of the protrusion is gradually increased while continuously changing. A protrusion having a width of 0.2 to 5.0 mm and a height of 0.1 to 5.0 mm extending along the tire circumferential direction on the outer surface of the sidewall portion, the protrusion having the smallest protrusion width A pneumatic tire formed so that the protrusion width gradually becomes narrower toward the narrowest part, and the surface of the narrowest part has a cut mark obtained by removing spew . The pneumatic tire according to claim 15, wherein the width of the protrusion is gradually narrowed while being continuously changed.

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