Patent Application
20240066822
The present invention relates to a sipe blade for forming sipes in a tire and a tire mold.
Conventionally, in tires, by forming narrow grooves (so-called sipes), which have narrower widths than groove widths of main grooves, in tread blocks demarcated by the main grooves extending in the circumferential direction and in the width direction, a gripping force on ice is improved by controlling a block rigidity or increasing edges. Normally, a mold for molding such tires is manufactured by a casting process, however, if a part, which is used to mold such sipes as described above, especially sipes having a groove width of about 2 mm or less, is formed integrally with another part by casting in, there is a great danger of breakage of that part due to loads repeatedly applied at the time of tire molding and demolding. Thus, to cope with this, a thin member (a sipe blade) having been separately manufactured by press molding a metal plate or the like made of a steel material with higher strength, is casted in to the above-mentioned part.
As described above, by press-molding the steel material of the sipe blade, a certain degree of freedom is obtained in setting of the shape of the sipe. On the other hand, since the sipe blade obtained by press-molding the steel material cannot be largely changed, in terms of the thickness thereof, there is a problem that the degree of freedom in changing the shape of the groove width, namely, partially widening the groove width of the sipe and so on, is low.
It is therefore an object of the present invention to provide a sipe blade and a tire mold capable of improving the degree of freedom in setting the sipe shape in a tire while assuring a repeated fatigue life of the sipe blade.
As a configuration of a sipe blade for solving the above-described problem, a sipe blade which is implanted in a base mold and which molds a sipe in a tire is configured to include a first blade molded by pressing a plate member and a second blade having a thickness greater than a thickness of the first blade, in which the second blade is provided with a contact portion which extends along an outer periphery of the first blade implanted in the base mold and with which one molding surface of the first blade comes in contact along a peripheral edge portion of the first blade, or provided with a fitting portion which accommodates the peripheral edge portion of the first blade and with which both molding surfaces of the first blade come in contact.
Further, as a configuration of a tire mold for solving the above-described problem, a tire mold is provided with the sipe blade having the above-described configuration.
It should be noted that the above-described summary of the invention does not enumerate all the necessary features of the present invention, and respective configurations constituting the feature groups can also be the invention.
Hereinafter, the present invention will be explained in detail through embodiments, however, the embodiments described below do not limit the inventions set forth in the claims, and not all of combinations of the features described in the embodiments are necessarily essential to the solving means of the invention.
As illustrated in
As illustrated in
The blade attachment portion 12 extends along the tire width direction from one of the adjacent circumferential direction groove molding portions 10, 10 so as to reach the other one of the adjacent circumferential direction groove molding portions 10, 10. The blade attachment portion 12 is configured with a first blade attachment portion 14 for attaching the first blade 40 and a second blade attachment portion 16 for attaching the second blade 60. The first blade 40 and the second blade 60 configure the sipe blade 4.
The first blade attachment portion 14 is provided to linearly extend so as to connect between the circumferential direction groove molding portions 10; 10. The first blade attachment portion 14 is formed as a groove that is recessed in a slit shape into a grounding surface molding portion 11, which molds a grounding surface of the tire, of the molding surface 2a of the base mold 2. The first blade attachment portion 14 is provided, along the tire width direction, with a plurality of convex portions 18 for fixing the first blade 40. The convex portion 18 is formed so as to swell in a spherical shape from a groove wall 14a forming the first blade attachment portion 14.
The second blade attachment portion 16 is provided in the circumferential direction groove molding portion 10. The second blade attachment portion 16 is recessed toward the outside in the tire width direction from a groove wall molding portion 10A, which forms the groove wall of the circumferential direction groove of the circumferential direction groove molding portion 10 in the tire, extends in the tire radial direction from a groove bottom molding portion 10B, which forms the groove bottom of the circumferential direction groove of the circumferential groove molding portion 10 in the tire, and is formed as a concave portion recessed more than the grounding surface molding portion 11 configuring the molding surface 2a.
As illustrated in
The first blade 40 is provided with a plurality of circular engagement holes 42 that penetrate in a plate thickness direction and that engages with the convex portion 18 provided in the first blade attachment portion 14. The first blade 40 is attached to the base mold 2 at a predetermined position in such a manner as not to fall off by engaging the engagement hole 42 with the convex portion 18 provided in the first blade attachment portion 14.
The strut portions 62, 62 are attached to the second blade attachment portions 16, 16 of the base mold 2, respectively, and, as illustrated in
As illustrated in
The accommodation groove 66 is configured with strut portion grooves 67; 67 formed in the strut portion 62 and a coupling portion groove 68 formed in the coupling portion 64. The strut portion grooves 67; 67 formed in each of the strut portions 62; 62 face each other and extend parallel to each other from one end 62t in the extension direction of each of the strut portions 62; 62 to the coupling portion 64 along the extension direction of the strut portion 62. The coupling portion groove 68 extends along the extension direction of the coupling portion 64 and is connected to the strut portion grooves 67; 67 provided in each of the strut portions 62; 62.
The groove width L3 of the accommodation groove 66 is so formed that the short sides of the first blade 40 can be inserted from one end 62t; 62t sides of the strut portion grooves 67; 67 in a manner that the first blade 40 can be slidable toward the coupling portion 64, and that one long side of the first blade 40 can be inserted into the coupling portion groove 68. In other words, by fitting the first blade 40 into the accommodation groove 66 of the second blade 60, the first blade 40 and the second blade 60 are integrated as one ripe blade 4.
Hereinafter, an explanation is given as to the relationship between the second blade 60 and the first blade 40 when the second blade 60 and the first blade 40 are integrated.
As illustrated in the enlarged views of
As illustrated in
As described above, the sipe blade 4 is inserted into the blade attachment portion 12 of the base mold 2, for example, in the state in which the first blade 40 is combined with the second blade 60, and configures a part of the tire mold 1. In the state of being attached to the base mold 2, the sipe blade 4 can change the groove width, in the tire radial direction, of one sipe when the tire is molded, as the first blade 40 and the coupling portion 64 of the second blade 60, which have different thicknesses, are exposed between the circumferential direction groove molding portions 10; 1.0.
In this way, namely, it is possible to mold a narrow groove extending in the tire radial direction from the grounding surface of the tire by the first blade 40 which is thin in the thickness, and mold a wide groove having a wide groove width by the second blade 60 which is greater in the thickness than that of the first blade 40 on the groove bottom side of this narrow groove. By molding the sipe in this manner, water entering into the narrow groove from the grounding surface side can be efficiently drained from the wide groove on the groove bottom side to the circumferential direction groove.
In this way, by using a member, which is formed by pressing a plate member, for the portion of the sipe where the narrow groove is molded, and by forming, by the additive manufacturing method, the portion where the wide groove is molded, advantages of each manufacturing method can be utilized and the durability of the sipe blade 4 can be improved. In other words, if the sipe blade for molding the narrow groove is formed by the additive manufacturing method, the durability is degraded, however, this can be prevented by using a plate member.
The sipe blade 4 according to the present embodiment differs from the aforementioned sipe blade 4 in that the sipe blade 4 according to the present embodiment is provided with the vent passage 70 that makes it possible to exhaust air intervening between the tire mold 1 and a green tire during tire molding. As illustrated in
Since the accommodation groove 66 is formed by the additive manufacturing method and the first blade 40 is formed by pressing the plate member, the surface roughness differs from each other. More specifically, the surface of the first blade 40 is smoother than the surface roughness (the visible roughness inherent to the additive manufacturing method) of the second blade 60 formed by the additive manufacturing method. Due to this difference in the surface roughness, a gap is formed between the first blade 40 and the second blade 60, which allows air to flow into the vent passage 70. This gap may be utilized as an introduction path to the vent passage 70.
In the case of configuring the sipe blade 4 in this manner, as illustrated in FIGS. GA to GC, it is desirable to provide, in the base mold 2, vent holes 20 that penetrate to the second blade attachment portion 16 to which the strut portions 62; 62 of the second blade 60 are attached, and to the back surface 2b of the base mold 2. By configuring the base mold 2 in this manner, air intervening between the green tire and the molding surface 2a can be efficiently discharged when molding the tire, thus it is unnecessary to provide the vent hole in another part of the base mold 2. In addition, with this configuration, air can be discharged from the vent hole 20 provided in the base mold 2. Further, because the gap formed by the difference in the surface roughness is such a degree to which rubber hardly enters, not only the air can be discharged through the sipe blade 4, but also spews (molding mark) are not molded on the surface of the tire. Thus, the appearance of the tire after molding can be improved.
The second blade 60 may be formed by the additive manufacturing method to have the support portions 62; 62 and the coupling portion 64 as separate members, as illustrated in
As illustrated in
As illustrated in
In the second blade 60, groove-shaped accommodation grooves (corresponding to the above-described accommodation groove 66) extending along the extension direction of the plate thickness surface 61m and into which the outer peripheries of the first blades 40A to 40C can be inserted, are formed in the plate thickness surface 61m forming the openings 61A; 61B; (31C. The Sipe blade 4 may be formed as shown in this Embodiment 4.
Incidentally, it should be noted that the thicknesses of the first blades 40A to 40C may be set appropriately, namely, may be set to be the same or may be set to be different for each blade or may be set such that two of the first blades may be set, to have the same thickness and the remaining one may be set to have a different thickness. Even when the thicknesses of the first blades 40A to 40C are changed as described above, by forming the second blade 60 by the additive manufacturing method, it is possible to easily change the groove width for accommodating the first blades 40A to 40C and form the groove.
In the above-described Embodiments 1 to 4, it has been explained that the sipe blade 4 extends so as to reach between the circumferential direction groove molding portions 10; 10, however, it is not limited thereto. As illustrated in
The sipe blade 4 according to Embodiment 5 is provided in such a manner that the second blade 60 comes in contact with the first blade 40. That is, in the above-described. Embodiments 1 to 4, it has been explained that the second blade 60 is formed so as to support the molding surfaces 40m; 40m of the first blade 40 by the pair of groove walls 66m: 60m that form the accommodation groove 66. However, as illustrated in
As illustrated in
By forming the opposing wall 72n so as to have the predetermined gap relative to the outer peripheral surface 40a of the first blade 40, the opposing wall 72n may be made movable with respect to the second blade 60 when an external force acts on the first blade 40. Namely, because it is possible to be displaced relative to the second blade 60 when the tire mold 1 is demolded from the tire, for example, occurrence of defects such as damaging the tire when & molding can be suppressed and the force acting on the first blade 40 can be released, it is possible to prevent unnecessary deformation of the first blade 40 and improve the durability of the sipe blade 4.
In the case of setting different thicknesses to the sipe blade 4, by combining the first blade 40 and the second blade 60 that are different in the thickness to form one sipe blade 4 for molding the tire, and by molding the narrow groove in the tire by the first blade 40 and by molding a groove, having a wide groove width, on the groove bottom side of the sipe by the second blade 60 having the thickness greater than that of the first blade 40, it is possible to improve, while gaining an edge effect on ice and snow by the portion molded by the first blade 40, the performance of drainage of water entered into the groove by the portion molded by the second blade 60.
As explained above using each of Embodiments 1 to 5, by configuring the sipe blade 4 that molds one sipe (narrow groove) in the tire, with two different materials, which are: the first blade 40 that is formed by pressing the metal plate; and the second blade 60 that is formed by the additive manufacturing method and that molds the wide groove in the sipe, it is also possible to maintain the durability of the sipe blade 4 while maintaining the degree of freedom of design in the sipe formation.
It should be noted that the number of parts configuring the sipe blade 4 and the shape of the parts configuring the sipe blade 4 are not limited to those shown in each of the above-described Embodiments, and may be changed appropriately.
For example, in setting the sipe blade 4, like the second blade 60, by forming a part of the sipe blade by the additive manufacturing method, it is possible to maintain the degree of freedom in setting the shape. In addition, by utilizing a press-molded metal plate, like the first blade 40, for the part where the strength is insufficient (the portion where the thickness is desired to be reduced) when formed by the additive manufacturing method, even in the case of molding a groove width of about 0.2 mm, for example, it is possible to prevent breakage at the time of demolding, and maintain the durability.
In other words, it is possible to provide a durable sipe blade and a tire mold while utilizing the superiority of the degree of freedom in forming the sipe on the tire by the additive manufacturing method.
Incidentally, in the above description, it has been explained that the second blade 60 having a thickness greater than that of the first blade 40 is formed by the additive manufacturing method, however, it may be manufactured by precision casting or machining in a process different from forming of the base mold, for example.
Further, it has been explained that, in Embodiment 2, the vent passage 70 is provided in the second blade 60 and the vent hole 20 is provided in the base mold 2 so as to be communicated with the vent passage 70. However, in a case in which the vent passage 70 is not provided in the second blade 60 (for example, like in Embodiment 1 and Embodiments 3 to 5), it is desirable to provide the vent hole 20 in the base mold 2 in such a manner that the vent hole 20 opens to the accommodation groove 66 opened at one end. 62t of each strut portion 62 of the second blade 60 attached to the base mold. 2. As described above, the first blade 40 is formed by pressing the plate member, and the second blade 60 is formed by the additive manufacturing method. For this reason, the surface of the first blade 40 is smoother than the surface roughness (the visible roughness inherent to the additive manufacturing method) of the second blade 60 formed by the additive manufacturing method. Because a gap is formed between the first blade 40 and the second blade 60 due to this difference in the surface roughness, by utilizing this gap as a vent passage, air can be discharged from the vent hole 20 provided in the base mold 2. In addition, since the gap formed by the difference in the surface roughness is such a degree to which rubber hardly enters, it has an advantage that molding marks such as spews are less likely to remain in the tire after molding.
It should be noted that the manufacturing method of the tire mold is not limited to attaching the ripe blade 4 to the blade attachment portion 12 provided in the base mold 2, as described above. The sipe blade 4 may be embedded and integrated by casting in or the like, for example, when casting the base mold 2.
As explained above, a sipe blade which is implanted in a base mold and which molds a sipe in a tire is so configured that the sipe blade includes a first blade molded by pressing a plate member and a second blade having a thickness greater than a thickness of the first blade, in which the second blade is provided with a contact portion which extends along an outer periphery of the first blade implanted in the base mold and with which one molding surface of the first blade comes in contact along a peripheral edge portion of the first blade, or provided with a fitting portion which accommodates the peripheral edge portion of the first blade and with which both molding surfaces of the first blade come in contact. With this configuration, it is possible to improve the degree of freedom in setting of the sipe shape and, even for the sipe blade having a special shape, it is possible to manufacture the sipe blade with a repetitive fatigue life without a practical problem.
Further, by configuring such that a part of the second blade is included in a part of the molded item to be molded in the tire by the base mold, it is possible to improve the durability due to the undercut shape caused by a 3D bent shape of the sipe blade.
Further, by configuring such that a gap, which is generated in the contact portion where the first blade and the second blade come in contact or which is generated in the fitting portion, is communicated with the vent hole provided in the base mold, air can be discharged through the gap generated in the contact portion or in the fitting portion of the second blade. Therefore, it is unnecessary to provide the vent hole separately at another position of the base mold 2, and it is possible to suppress the occurrence of spews during tire molding.
Further, by providing the second blade with a groove that is communicated with the vent hole and extends along the contact portion where the first blade and the second blade come in contact or along the fitting portion, it is possible to discharge more of the air. It is also possible to further suppress the occurrence of spews during tire molding.
Further, by configuring such that a tire mold is provided with the ripe blade according to any of claims 1 to 6, the durability of the tire mold can be improved.
1: Tire mold, 2: Base mold, 4: Sipe blade, 20: Vent hole, 40: First blade, 60: Second blade, 66: Accommodation groove, 70: Vent passage.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-010847 | Jan 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/041149 | 11/9/2021 | WO |
