JP6834635B2 - How to manufacture airless tires and airless tires - Google Patents

Description

The present invention relates to a method for manufacturing an airless tire that suppresses partial peeling of a tread ring and spokes due to heat shrinkage of a polymer material during casting, and an airless tire.

Patent Document 1 below proposes, as an airless tire applicable to passenger cars, a structure in which a tread ring and a hub are connected by spokes having plate-shaped spoke bodies arranged in a radial pattern. Has been done.

In the proposed airless tire, in order to increase the adhesive strength between the tread ring and the spokes, a rough surface treatment and an adhesive are applied to the inner peripheral surface of the vulcanized tread ring, respectively. After that, the tread ring and the hub are put into the casting mold, and the raw material liquid of the polymer material for forming the spokes is injected and cured to integrate the spokes, the tread ring and the hub.

However, as shown in an exaggerated manner in FIG. 10, when the polymer material is cured, heat shrinkage occurs, and the plate-shaped spoke body a1 shrinks in the length direction thereof. At this time, at the intersection x between the outer annular portion a2 of the spoke a and the spoke body a1, a force F in the direction of pulling the outer annular portion a2 inward in the radial direction acts. As a result, partial peeling j of the outer annular portion a2 from the tread ring b tends to occur at the intersection x.

International Publication WO2014 / 188912

Therefore, an object of the present invention is to provide a method for manufacturing an airless tire that suppresses partial peeling between the tread ring and the spokes due to heat shrinkage of the polymer material during casting, and to provide an airless tire.

The first invention of the present application is from a cylindrical tread ring having a ground plane, a hub arranged inside the tread ring in the radial direction and fixed to an axle, and a polymer material connecting the tread ring and the hub. It is a method of manufacturing airless tires with spokes.
A raw tread forming step of forming a raw tread ring by sequentially winding tread components including tread rubber on the tread forming surface of a cylindrical rigid core having a tread forming surface on the outer peripheral surface.
A tread vulcanization step in which the raw tread ring is put into a vulcanization die together with a rigid core and vulcanized by heating.
The hub and the pre-vulcanized tread ring removed from the rigid core are mounted in a casting die, and the height is high in the casting die and in the space between the pre-vulcanized tread ring and the hub. It is equipped with a casting process that integrates the spokes, the vulcanized tread ring, and the hub by injecting and curing the raw material liquid of the molecular material.
The rigid core is provided with a plurality of grooves extending from one side edge side in the axial direction of the tread forming surface to the other side edge side on the tread forming surface, whereby the tread vulcanization step has already been added. The inner peripheral surface of the vulcanization tread ring is characterized by forming ridges on which the grooves are transferred.

In the method for manufacturing an airless tire according to the present invention, the total opening area SA, which is the sum of the areas of the openings of the grooves on the tread forming surface, is the surface area S0 of the tread forming surface when the grooves are not formed. It is preferably 30 to 70%.

In the method for manufacturing an airless tire according to the present invention, the total surface area SB of the tread forming surface including the surface area of each groove is 130% or more of the surface area S0 of the tread forming surface when the groove is not formed. preferable.

In the method for manufacturing an airless tire according to the present invention, it is preferable that the groove is formed parallel to the tire axial direction.

In the method for manufacturing an airless tire according to the present invention, an adhesive coating step of applying an adhesive to the inner peripheral surface of a pre-vulcanized tread ring removed from the rigid core is provided before the casting molding step. It is preferable to obtain.

The second invention of the present application is an airless tire formed by the manufacturing method of the first invention, and is on the inner peripheral surface of the tread ring from one side edge side to the other side edge side in the axial direction of the inner peripheral surface. It is characterized by having multiple ridges that extend.

In the first invention, as described above, a raw tread ring is formed using a rigid core having a plurality of grooves on the tread forming surface, and the raw tread ring is vulcanized together with the rigid core. It is put inside and vulcanized by heating. Therefore, a plurality of ridges to which the grooves are transferred are formed on the inner peripheral surface of the pre-vulcanized tread ring.

The ridges increase the contact area between the tread ring and the polymer material, and the ridges bite into the polymer material, so that the bonding strength can be increased as compared with the rough surface treatment. As a result, it is possible to suppress the occurrence of partial peeling between the spokes and the tread ring due to heat shrinkage of the polymer material during casting molding. In addition, the rough surface treatment process becomes unnecessary, which can contribute to the improvement of productivity.

It is a perspective view which shows an Example of the airless tire formed by the manufacturing method of this invention. It is sectional drawing in the tire axial direction which shows the airless tire. It is a perspective view which shows the tread ring used for the airless tire. It is a partial cross-sectional view in the direction perpendicular to the tire axis which shows the joint part of the tread ring and the spoke enlarged. It is a conceptual diagram which shows the raw tread forming process, the tread vulcanization process, and the adhesive application process. (A) and (B) are conceptual diagrams showing a casting molding process. (A) to (D) are cross-sectional views illustrating the cross-sectional shapes of the grooves and the ridges. (A) to (E) are pattern diagrams of a groove and a ridge. It is a partial cross-sectional view of the tread forming surface explaining the total surface area SB. It is a partial enlarged view which exaggerates the partial peeling of a spoke from a tread ring.

Hereinafter, embodiments of the present invention will be described in detail.
FIGS. 1 and 2 show an example of an airless tire 1 formed by the manufacturing method of the present invention. The airless tire 1 connects a cylindrical tread ring 2 having a ground contact surface 2s, a hub 3 arranged inside the tread ring 2 in the radial direction and fixed to an axle J, and the tread ring 2 and the hub 3. It is equipped with spokes 4 made of a tread. In this example, the case where the airless tire 1 is formed as a passenger car tire is shown.

The tread ring 2 is a portion corresponding to a tread portion in a pneumatic tire, and is composed of a tread component member Tg including a tread rubber 2A. In this example, the tread component Tg includes a tread rubber 2A and a reinforcing cord layer 2B embedded therein. As the tread rubber 2A, a rubber composition having excellent frictional force against grounding and abrasion resistance is preferably adopted. The reinforcing cord layer 2B includes a first cord ply 2B1 in which tire cords are arranged at an angle of, for example, 10 to 45 degrees with respect to the tire circumferential direction, and a first cord ply 2B1 in which the tire cord is spirally wound in the tire circumferential direction. The code ply 2B2 of 2 can be used in appropriate combination.

The hub 3 corresponds to a tire wheel, and in this example, a disk-shaped disc portion 3A fixed to the axle J and a cylindrical disc portion 3A integrally formed at the outer end portion in the radial direction of the disc portion 3A. It is equipped with a spoke mounting portion 3B. A hub hole 3A1 through which the front end portion Ja of the axle J is inserted is formed in the center of the disk portion 3A. Further, around the hub hole 3A1, a plurality of bolt insertion holes 3A2 for fixing the bolt portion Jb arranged on the axle side with a nut are provided.

Like a conventional tire wheel, such a hub 3 is separately formed of a metal material such as steel, an aluminum alloy, or a magnesium alloy.

The spoke 4 is a cast molded body made of a polymer material, and in this example, the outer annular portion 4A, the inner annular portion 4B, and the outer annular portion 4A and the inner annular portion 4B are connected radially. It is formed from a plurality of plate-shaped spoke bodies 4C. As the polymer material, for example, a thermosetting resin such as an epoxy resin, a phenol resin, a polyurethane resin, or a melamine resin is preferably used, but a polyurethane resin is more preferably used because it has excellent elastic properties. Can be done.

The outer annular portion 4A and the inner annular portion 4B are cylindrical bodies concentric with the axle J, respectively, and are integrally joined to the inner peripheral surface of the tread ring 2 and the outer peripheral surface of the hub 3 by casting. Further, the spoke body 4C of this example is composed of a first spoke body 4C1 that is inclined to one side with respect to the tire axial direction and a second spoke body 4C2 that is inclined to the other side, and the first and second spoke bodies are described above. The spoke bodies 4C1 and 4C2 are arranged alternately in the tire circumferential direction. In this example, the case where the first and second spoke bodies 4C1 and 4C2 are continuous in a zigzag shape is shown, but the first and second spoke bodies 4C1 and 4C2 may be separated in the circumferential direction.

As shown in FIG. 3, a plurality of ridges 5 extending from one side edge 2E1 side to the other side edge 2E2 side in the axial direction of the inner peripheral surface are projected on the inner peripheral surface of the tread ring 2. To. In this example, the case where the ridge 5 extends from the one side edge 2E1 to the other side edge 2E2 is shown, but it may be terminated before the one side edge 2E1 and the other side edge 2E2.

As shown in FIG. 4, the ridge 5 increases the contact area between the tread ring 2 and the outer annular portion 4A (spoke 4), and the ridge 5 bites into the outer annular portion 4A, whereby the tread ring 2 The joint strength between the surface and the outer annular portion 4A can be increased. As a result, it is possible to suppress the occurrence of partial peeling between the outer annular portion 4A (spoke 4) and the tread ring 2 due to heat shrinkage of the polymer material when the spoke 4 is cast-molded. ..

In this example, an adhesive layer 6 made of an adhesive 6a is formed on the inner peripheral surface of the tread ring 2 including the ridges 5, and the bonding strength is further formed.

The ridges 5 are provided on the tread forming surface 10s of the rigid core 10 as shown in FIG. 5 when the tread ring 2 is vulcanized as described in the method for manufacturing the airless tire 1 described later. The groove 11 is formed by being transferred to the inner peripheral surface of the tread ring 2. Therefore, the ridge 5 has substantially the same shape as the groove 11, and the cross-sectional shape, size, and arrangement pattern thereof will be described in the groove 11 described later.

Next, a method of manufacturing the airless tire 1 will be described. As shown in FIGS. 5 and 6, this manufacturing method includes a raw tread forming step K1, a tread vulcanization step K2, and a casting molding step K3.

As shown in FIG. 5, in the raw tread forming step K1, a cylindrical rigid core 10 having a tread forming surface 10s on the outer peripheral surface is used. Then, the raw tread ring 2R is formed by sequentially winding the unvulcanized tread component Tg containing the tread rubber 2A on the tread forming surface 10s of the rotating rigid core 10.

In the present invention, the rigid core 10 is provided with a plurality of grooves 11 extending from the one side edge 10E1 side of the tread forming surface 10s in the axial direction i direction to the other side edge 10E2 side on the tread forming surface 10s. To. In this example, the case where each groove 11 extends from the one side edge 10E1 to the other side edge 10E2 is shown, but it may be terminated before the one side edge 10E1 and the other side edge 10E2.

The cross-sectional shape of the groove 11 is, for example, a rectangular shape 11a (FIG. 7 (A)), a triangular shape 11b (FIG. 7 (B)), or a semicircular shape, as illustrated in FIGS. 7 (A) to 7 (D). Various types such as 11c (FIG. 7 (C)) and wedge-shaped shape 11d (FIG. 7 (D)) can be adopted. In particular, from the viewpoint of ease of removal of the tread ring 2 (sometimes referred to as "pre-sulfurized tread ring 2") from the rigid core 10 (sometimes referred to as "tread ring removableness"), 11b The triangular shape 11b is most preferable in the order of> 11c> 11a> 11d. Further, from the viewpoint of suppressing peeling between the tread ring 2 and the spokes 4 during casting (hereinafter referred to as “spoke peeling suppression”), the wedge shape 11d is most preferable in the order of 11b <11c <11a <11d.

The size of the groove 11 is not particularly limited, but the opening width W is preferably 2 to 5 mm and the depth h is preferably 0.5 to 2.5 mm. The depth h is smaller than the thickness t (shown in FIG. 4) of the outer annular portion 4A, and is preferably 10 to 50% of the thickness t. If the depth h exceeds 2.5 mm, the strength of the outer annular portion 4A tends to decrease, and conversely, if it is less than 0.5 mm, the contact area cannot be sufficiently increased and the effect of suppressing spoke peeling is reduced.

The arrangement pattern of the groove 11 is as shown in FIGS. 8A to 8E.
(1) Pattern Pa (FIG. 8 (A)) formed from the groove 11A parallel to the axial center i direction,
(2) Pattern Pb (FIG. 8 (B)) formed from the groove 11B inclined to one side at a constant angle θ with respect to the axial center i direction.
(3) A pattern Pc (FIG. 8 (C)) formed by a groove 11B inclined to one side at a constant angle θ and a groove 11C inclined to the other side at a constant angle θ.
(4) A pattern Pd (FIG. 8 (D)) formed from a parabolic groove 11D that is convex on one side in the circumferential direction with the width center wi of the rigid core 10 as the target axis.
(5) Various patterns Pe (FIG. 8 (E)) formed by a parabolic groove 11D that is convex on one side in the circumferential direction and a parabolic groove 11E that is convex on the other side in the circumferential direction. Things can be adopted.

As shown in FIG. 5, in the tread vulcanization step K2, the raw tread ring 2R is put into the vulcanization die 12 together with the rigid core 10 and vulcanized by heating. The vulcanization die 12 of this example includes a side mold 12a for molding the side surface of the tread ring 2 and a tread mold 12b for molding the outer peripheral surface, and the tread mold 12b is divided in the circumferential direction and inside and outside in the radial direction. It is composed of a plurality of segments 12b1 that can be moved to.

Then, the existing vulcanized tread ring 2 is vulcanized and molded with high accuracy by heating the raw tread ring 2R between the rigid core 10 and the vulcanization die 12 while pressurizing the raw tread ring 2R. At this time, the rubber of the raw tread ring 2R enters the groove 11, so that the ridge 5 on which the groove 11 is transferred is formed on the inner peripheral surface of the already vulcanized tread ring 2.

Further, after the vulcanized tread ring 2 is taken out from the vulcanization mold 12 together with the rigid core 10, the vulcanized tread ring 2 is removed from the rigid core 10 by the tread ring taking-out step Ka.

Here, in the case of the patterns Pa and Pb, the tread ring 2 can be removed by pushing out the tread ring 2 in the axial direction i direction without reducing the diameter of the rigid core 10. Therefore, there is an advantage that the structure of the rigid core 10 can be simplified, and it can be preferably adopted. In the pattern Pb, the tread ring 2 can be removed by pushing the rigid core 10 in the direction of the axis i while rotating it around the axis i. On the other hand, in the case of the patterns Pc to Pe, it is necessary to reduce the diameter of the rigid core 10 when removing the tread ring 2, which is disadvantageous in that the structure of the rigid core 10 is complicated.

As shown in FIGS. 6A and 6B, in the casting step K3, the spokes 4 are formed by casting. Specifically, by mounting the hub 3 and the pre-vulcanized tread ring 2 in the casting mold 30, the hub 3 can be placed in the casting mold 30 and between the pre-vulcanized tread ring 2 and the hub 3. A space portion H corresponding to the spoke 4 is formed. Then, by injecting and curing the raw material liquid of the polymer material into the space H, an airless tire 1 in which the spokes 4, the vulcanized tread ring 2 and the hub 3 are integrated is formed.

In this example, as shown in FIG. 5, an adhesive coating step of applying the adhesive 6a to the inner peripheral surface of the already vulcanized tread ring 2 removed from the rigid core 10 before the casting molding step K3. K4 is performed. The casting molding step K3 is performed after the applied adhesive 6a has dried.

As the adhesive 6a, various adhesives such as latex type, solvent type, and reactive type can be appropriately selected depending on the material of the adherend. For example, when the spoke 4 is a urethane-based resin, for example, an adhesive represented by the trade name "Chemlock 218E" manufactured by Rhodefar East Co., Ltd. is preferably adopted.

Here, in order to suppress peeling of the tread ring 2 and the outer annular portion 4A (spoke 4) due to heat shrinkage of the polymer material, the sum of the areas sa of the openings of the grooves 11 on the tread forming surface 10s. The total opening area SA is 30 to 70%, more preferably 50 to 70% of the surface area S0 of the tread forming surface when the groove 11 is not formed. When the total opening area SA is less than 30% of the surface area S0, the contact area is reduced and the peeling suppressing effect is lowered. On the contrary, even if it exceeds 70%, poor flow of the polymer material is likely to occur between the ridges 5 and 5, and similarly, the effect of suppressing spoke peeling is lowered.

Further, the total surface area SB of the tread forming surface 10s including the surface area sb of each groove 11 is preferably 130% or more of the surface area S0 of the tread forming surface 10s when the groove 11 is not formed. As a result, the contact area is secured and a sufficient peeling suppressing effect is exhibited. As shown in FIG. 9, the total surface area SB is shown as the sum of the total surface area sb of each groove 11 and the total area sc of the area sc between the grooves 11 and 11 on the tread forming surface 10s. .. Further, the surface area sb of the groove 11 includes the area of the groove side surface and the area of the groove bottom of the groove 11.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified into various embodiments.

Based on the manufacturing method of the present invention shown in FIGS. 5 and 6, 10 airless tires (tires corresponding to tire sizes 145 / 70R12) having the structure shown in FIG. The sex and the effect of suppressing spoke peeling were tested. Grooves are formed on the tread forming surface of the rigid core based on the specifications in Table 1.

Each tire has substantially the same specifications except for the groove, and urethane resin is used for the spokes, and "Chemlock 218E" (trade name manufactured by Road Far East Corporation) is used as the adhesive. .. As Comparative Example 1, instead of the groove, the tread-forming surface is roughened with a surface roughness Ra (arithmetic mean roughness) of 10 μm.

(1) Tread ring removable:
After the tread vulcanization step, the tread ring was removed from the rigid core by pushing the tread ring in the axial direction without reducing the diameter of the rigid core. The ease of removal at that time was shown by a 10-point method by sensory evaluation of workers. The larger the number, the better. 4 points or more pass.

(2) Spoke peeling inhibitory effect:
After the casting step, the state of peeling between the tread ring 2 and the spokes 4 due to heat shrinkage of the urethane resin was visually inspected, and was shown by a 10-point method by a sensory evaluation by an inspector. The larger the number, the better. 4 points or more pass.

As shown in Table 1, it can be confirmed that in the examples, the spoke peeling suppressing effect is exhibited as compared with the comparative example 1. As shown in Example 3, if the total opening area SA of the groove is too small, the spoke peeling suppressing effect is reduced. Further, as shown in Example 2, even if the total opening area SA of the groove is too large, the polymer material (urethane resin) does not sufficiently flow in and the spoke peeling suppressing effect is reduced. Therefore, the total opening area SA of the groove is preferably 30 to 75%, more preferably 30 to 70% of the surface area S0. The total surface area SB of the tread-forming surface is preferably 125% or more, more preferably 130% or more of the surface area S0 from Example 3.

Regarding the tread ring removability, although the example is lower than the comparative example, when the arrangement pattern of the groove is Pa or Pb, the cross-sectional shape is triangular, rectangular, semicircular, or wedge-shaped. It can be confirmed that all of them can be extruded in the axial direction.

1 Airless tire 2 Tread ring 2A Tread rubber 2R Raw tread ring 2s Ground surface 3 Hub 4 Spoke 5 Convex 6a Adhesive 10 Rigid core 10s Tread forming surface 11 Groove 12 Vulcanization mold 30 Casting mold H Space K1 Raw tread forming process K2 Tread vulcanization process K3 Casting molding process K4 Adhesive coating process Tg tread components

Claims (6)

An airless tire equipped with a cylindrical tread ring having a ground contact surface, a hub arranged radially inside the tread ring and fixed to an axle, and spokes made of a polymer material connecting the tread ring and the hub. It is a manufacturing method of
A raw tread forming step of forming a raw tread ring by sequentially winding tread components including tread rubber on the tread forming surface of a cylindrical rigid core having a tread forming surface on the outer peripheral surface.
A tread vulcanization step in which the raw tread ring is put into a vulcanization die together with a rigid core and vulcanized by heating.
The hub and the pre-vulcanized tread ring removed from the rigid core are mounted in a casting die, and the height is high in the casting die and in the space between the pre-vulcanized tread ring and the hub. It is equipped with a casting process that integrates the spokes, the vulcanized tread ring, and the hub by injecting and curing the raw material liquid of the molecular material.
The rigid core is provided with a plurality of grooves extending from one side edge side in the axial direction of the tread forming surface to the other side edge side on the tread forming surface, whereby the tread smelting step has already been added. A method for manufacturing an airless tire, which comprises forming ridges on which the grooves are transferred on the inner peripheral surface of a sulfur tread ring. The total opening area SA, which is the sum of the areas of the openings of the grooves on the tread-forming surface, is 30 to 70% of the surface area S0 of the tread-forming surface when the grooves are not formed. Item 1. The method for manufacturing an airless tire according to item 1. The airless tire according to claim 1 or 2, wherein the total surface area SB of the tread forming surface including the surface area of each of the grooves is 130% or more of the surface area S0 of the tread forming surface when the grooves are not formed. Manufacturing method. The method for manufacturing an airless tire according to any one of claims 1 to 3, wherein the groove is formed parallel to the tire axial direction. Claims 1 to 4, wherein an adhesive application step of applying an adhesive to the inner peripheral surface of the already vulcanized tread ring removed from the rigid core is provided before the casting step. The method for manufacturing an airless tire according to any one. An airless tire formed by the manufacturing method according to any one of claims 1 to 5, which extends from one side edge side in the axial direction of the inner peripheral surface to the other side edge side on the inner peripheral surface of the tread ring. An airless tire characterized by having multiple ridges.

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