Method for manufacturing non-pneumatic tire

Abstract

The present invention provides a method for manufacturing a non-pneumatic tire capable of suppressing peeling of a ring member from a tread member. In a method for manufacturing a non-pneumatic tire (1) according to the present disclosure, the non-pneumatic tire (1) comprises: a ring member (12) having an inner cylinder (31), an outer cylinder (32) surrounding the inner cylinder (31) from the outside in the radial direction, and a connecting member (33) connecting the inner cylinder (31) and the outer cylinder (32); and a cylindrical tread member (13), the method for manufacturing the non-pneumatic tire (1) being characterized by comprising the steps of: inserting the tread member (13) into the cavity (102); closing the cavity (102) by moving the movable-side mold (130) in the direction of the fixed-side mold (110); and forming a ring member (12) by supplying a molten resin (R) to a space on the inner side of the tread member (13) in the tire radial direction (B), wherein the outer diameter of the outer peripheral surface (tread (13a)) of the tread member (13) before the ring member (12) is formed is smaller than the inner diameter of the inner peripheral surface (102a) of the cavity (102) facing the outer peripheral surface.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority based on Japanese Patent Application No. 2022-167045, filed on October 18, 2022, and the entire specification of that patent application is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a method for manufacturing a non-pneumatic tire. Background Art

[0004] In recent years, in order to avoid the occurrence of tire blowout, a tire that does not need to be filled with pressurized air (non-pneumatic tire) has been developed. The non-pneumatic tire disclosed in Patent Document 1 includes a mounting body mounted on an axle, a ring member having an inner cylinder body externally mounted on the mounting body and an outer cylinder body surrounding the inner cylinder body from the outer side of the tire radial direction, a plurality of connecting members arranged between the inner cylinder body and the outer cylinder body along the tire circumferential direction and connecting the inner cylinder body and the outer cylinder body in a relatively elastically displaceable manner, and a tread member arranged on the outer peripheral surface side of the outer cylinder body within the entire circumference of the outer cylinder body.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-193046 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] When manufacturing the non-pneumatic tire disclosed in Patent Document 1, it is necessary to perform surface treatment on the outer peripheral surface of the resin ring member, apply adhesive, and embed the tread member into the outer peripheral surface of the ring member. Therefore, a tooling mold is required in each process, resulting in an increase in manufacturing costs.

[0010] As a means for simplifying the manufacturing process of the non-pneumatic tire and reducing the manufacturing cost, it is conceivable to insert-mold a resin ring member using a tread member as an insert material.

[0011] However, when the tread member is insert-molded as an insert material in a resin ring member, the formed ring member may shrink radially inward during cooling and may be separated from the tread member. This point has room for improvement.

[0012] An object of the present disclosure is to provide a method for manufacturing a non-pneumatic tire capable of suppressing separation of a ring member from a tread member.

[0013] Solutions for solving problems

[0014] In order to solve the above-mentioned problems, the manufacturing method of the non-pneumatic tire disclosed in the present invention is as follows: [1]

[0016] The non-pneumatic tire includes: a ring member, which is integrally formed with an inner cylinder, an outer cylinder surrounding the inner cylinder from the radial outside of the tire, and an elastically deformable connecting member that connects the inner cylinder and the outer cylinder to each other; and a cylindrical tread member, which is installed on the radial outside of the ring member. The manufacturing method of the non-pneumatic tire is characterized by comprising the following steps: inserting the tread member into a mold cavity of a forming mold; moving the movable side mold toward the fixed side mold to close the mold cavity; and supplying molten resin to the space on the radial inside of the tread member in the mold cavity to form the ring member, wherein the outer diameter of the outer peripheral surface of the tread member before the ring member is formed is smaller than the inner diameter of the inner peripheral surface of the mold cavity opposite to the outer peripheral surface.

[0017] By adopting such a structure, when pressurized molten resin is supplied into the mold cavity, the tread of the tread member expands toward the outer side in the tire radial direction in a manner close to the inner peripheral surface of the mold cavity opposite to the tread. Afterwards, although the filled molten resin shrinks when cooled, the tread member expanded toward the outer side in the tire radial direction returns to its original shape following the shrinkage of the resin. Therefore, it is possible to prevent peeling from occurring between the inner peripheral surface of the tread member and the shrinking resin (ring member).

[0018] In addition, the manufacturing method of the non-pneumatic tire of the present disclosure is as follows, [2]

[0020] According to the configuration described in [1] above, preferably, the shrinkage rate of the tread member due to cooling of the molten resin is larger than the shrinkage rate of the ring member.

[0021] By adopting such a structure, when the molten resin is cooled, the inner circumferential surface of the tread member on the inner side of the tire radial direction shrinks to a greater extent than the outer circumferential surface of the ring member on the outer side of the tire radial direction. Therefore, a force is applied in a direction to make the outer circumferential surface of the ring member and the inner circumferential surface of the tread member closely fit, so that the outer circumferential surface of the ring member can be effectively prevented from peeling off from the inner circumferential surface of the tread member.

[0022] In addition, the manufacturing method of the non-pneumatic tire of the present disclosure is as follows, [3]

[0024] According to the configuration described in [1] or [2] above, preferably, the radial position of the inner circumferential surface of the tread member at the end position in the tire width direction before the ring member is formed is the same radial position as the outermost end in the tire radial direction at the end position in the tire width direction of the block member of the forming mold that forms the connecting member.

[0025] With such a configuration, the inner peripheral surface of the tread member is supported by the stopper member of the molding die over the entire circumference. Therefore, the tread member is less likely to be displaced due to the supply of molten resin, and can be stably inserted into the molding ring member.

[0026] In addition, the manufacturing method of the non-pneumatic tire of the present disclosure is as follows, [4]

[0028] According to any one of the above-mentioned configurations [1] to [3], preferably, the width of the tread member in the tire width direction before molding of the ring member is greater than the length of the cavity of the molding die in the tire width direction.

[0029] By adopting such a configuration, the space between the both ends of the tread member in the tire width direction and the mold cavity is effectively sealed, thereby effectively preventing the molten resin from leaking outward in the tire radial direction through the both ends of the tread member in the tire width direction.

[0030] In addition, the manufacturing method of the non-pneumatic tire of the present disclosure is as follows, [5]

[0032] According to any one of the above-mentioned structures [1] to [4], preferably, the stopper member of the forming mold is provided with a mold opening slope, which extends from one split mold of the forming mold to the other split mold, and is configured so that the top end portion of the stopper member is thinner than the base end portion.

[0033] By adopting such a configuration, it is possible to suppress the situation in which the stopper member collides with the inner peripheral surface of the tread member when the molding die is clamped.

[0034] In addition, the manufacturing method of the non-pneumatic tire of the present disclosure is as follows, [6]

[0036] According to the configuration described in any one of [1] to [5] above, preferably, the mold has a fitting groove for receiving a protrusion at an end portion in the tire width direction of the tread member.

[0037] By adopting such a structure, the sealing performance between the end of the tread member in the tire width direction and the mold cavity can be further improved, and the leakage of molten resin to the outer side of the tire radial direction can be effectively suppressed. In addition, by making the protrusion slightly protruding in the tire width direction than the ring member formed by the molten resin, it is possible to suppress the situation where the resin ring member directly collides with other objects and is damaged or damaged.

[0038] Effects of the Invention

[0039] According to the present disclosure, it is possible to provide a method for manufacturing a non-pneumatic tire capable of suppressing separation of a ring member from a tread member. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1A This is a side view of a non-pneumatic tire manufactured by the method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure.

[0041] Figure 1B yes Figure 1A An enlarged view of section I-I in FIG.

[0042] Figure 2 It is a front cross-sectional view of a forming mold used in the method for manufacturing a non-pneumatic tire according to one embodiment of the present disclosure.

[0043] Figure 3 This is a perspective view of a stopper member of a molding die used in the method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure.

[0044] Figure 4 This is a flowchart showing a process of implementing a method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure.

[0045] Figure 5 This is a front cross-sectional view of a mold in a state in the middle of mold clamping used in the method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure.

[0046] Figure 6 This is a front cross-sectional view showing a state where the filling of a molten resin into a molding die in the method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure begins.

[0047] Figure 7 This is a front cross-sectional view showing a state in which the filling of the molten resin into the molding die used in the method for manufacturing the non-pneumatic tire according to the embodiment of the present disclosure is completed.

[0048] Figure 8 It is an enlarged cross-sectional view showing a modified example of a tread member and a molding die. DETAILED DESCRIPTION

[0049] Hereinafter, the method for manufacturing a non-pneumatic tire of the present disclosure will be described with reference to the accompanying drawings. In each of the drawings, common components and locations are denoted by the same reference numerals.

[0050] Figure 1A The structure of a non-pneumatic tire 1 manufactured by the non-pneumatic tire manufacturing method according to one embodiment of the present disclosure is shown.

[0051] like Figure 1AAs shown, the non-pneumatic tire 1 includes a ring member 12 mounted on the outer side of the tire radial direction B of the mounting body 11 mounted on the axle 210a, and a cylindrical tread member 13 mounted on the outer side of the ring member 12 in the tire radial direction B. The non-pneumatic tire 1 of this embodiment is a so-called bottom load type non-pneumatic tire 1 that mainly supports the load by the portion of the ring member 12 below the axle 210a.

[0052] The mounting body 11 includes a cylindrical mounting cylinder 21 to which the top end of the axle 210a is mounted, a cylindrical outer circumferential cylinder 22 surrounding the mounting cylinder 21 from the outside in the tire radial direction B, and a plurality of ribs 23 connecting the mounting cylinder 21 and the outer circumferential cylinder 22. The outer circumferential cylinder 22 has a circumferential groove extending over the entire circumference of the tire circumferential direction C on the outer circumferential surface of the outer circumferential cylinder 22 on the outside in the tire radial direction B. By providing the mounting body 11, the ring member 12 including the inner cylinder 31, the outer cylinder 32 and the connecting member 33 can be easily mounted on the axle 210a.

[0053] The ring member 12 includes an inner cylindrical body 31 , an outer cylindrical body 32 surrounding the inner cylindrical body 31 from the outer side in the tire radial direction B, and an elastically deformable connecting member 33 connecting the inner cylindrical body 31 and the outer cylindrical body 32 to each other.

[0054] Here, the mounting tube 21, the outer peripheral tube 22, the inner tube 31, the outer tube 32, and the tread member 13 are arranged so that their central axes are coaxial (common central axis O). In addition, the mounting tube 21, the outer peripheral tube 22, the inner tube 31, the outer tube 32, and the tread member 13 are arranged so that the central parts in the tire width direction A are aligned with each other.

[0055] The mounting tube 21, the outer tube 22 and the ribs 23 of the mounting body 11 are integrally formed of a metal material such as aluminum alloy or a resin material such as polypropylene. Figure 2 The side view shown is a symmetrical configuration with the central axis O as a reference point.

[0056] The outer cylindrical body 32 of the ring member 12 is larger in size in the tire width direction A, that is, in width, than the inner cylindrical body 31 .

[0057] The connecting member 33 is composed of a plurality of connecting plate portions 33a arranged along the tire circumferential direction C. The plurality of connecting plate portions 33a are arranged point-symmetrically with respect to the central axis O between the inner cylinder 31 and the outer cylinder 32 of the ring member 12. In addition, the connecting plate portions 33a of the present embodiment have the same size and the same shape. In addition, the width of each connecting plate portion 33a in the tire width direction A of the present embodiment is smaller than the width of the outer cylinder 32 in the tire width direction A.

[0058] The connecting plate portions 33 a adjacent to each other in the tire circumferential direction C are arranged spaced apart from each other so as not to contact each other.

[0059] The outer end portion 33a1 of each connecting plate portion 33a, which is connected to the outer cylinder 32 on the outer side of the tire radial direction B, is located closer to the tire circumferential direction C than the inner end portion 33a2, which is connected to the inner cylinder 31 on the inner side of the tire radial direction B. In other words, the outer end portion 33a1 and the inner end portion 33a2 are arranged at different positions in the tire circumferential direction C. In this way, the connecting plate portion 33a can be used as a leaf spring that is easily elastically deformed in the tire radial direction B.

[0060] In the present embodiment, the inner cylinder 31, the outer cylinder 32 and the connecting member 33 are made of resin. As a result, the inner cylinder 31, the outer cylinder 32 and the connecting member 33 can be made lightweight. In the present embodiment, the inner cylinder 31, the outer cylinder 32 and the connecting member 33 are integrally formed of a resin material by insert molding using the tread member 13 as an embedded material. In addition, as a resin material, for example, it can also be only one resin material, a mixture containing two or more resin materials, or a mixture containing one or more resin materials and one or more elastomers. In addition, for example, additives such as an anti-aging agent, a plasticizer, a filler or a pigment can also be included. The resin material is preferably a thermoplastic resin.

[0061] Specifically, the resin material may include thermoplastic resins such as polyester and nylon, thermosetting resins such as vinyl ester resin and unsaturated polyester resin, and other synthetic resins. The resin material may also include fibers such as glass, carbon, graphite, aramid, polyethylene, and ceramic as reinforcing fibers.

[0062] In addition, the ring member 12 of the present embodiment is composed of the inner cylinder 31, the outer cylinder 32 and the connecting member 33 described above, but may also include other parts.

[0063] The ring member 12 is restricted from relative movement in the tire width direction A relative to the mounting body 11 by the inner cylinder 31 of the ring member 12 being accommodated in the circumferential groove defined on the outer peripheral surface of the outer peripheral cylinder portion 22 of the mounting body 11 in the tire radial direction B. In addition, the ring member 12 is restricted from relative movement in the tire circumferential direction C relative to the mounting body 11 by bolting the inner cylinder 31 of the ring member 12 and the outer peripheral cylinder portion 22 of the mounting body 11 with bolts 70. In this way, the ring member 12 of the present embodiment is fixed relative to the mounting body 11, but the fixing of the mounting body 11 and the ring member 12 is not limited to the above-mentioned fixing means. For example, the relative movement of the mounting body 11 and the ring member 12 in the tire circumferential direction C can also be restricted by fitting a convex portion of one of the outer peripheral surface of the outer peripheral cylinder portion 22 of the mounting body 11 and the inner peripheral surface of the inner cylinder 31 of the ring member 12 with a concave portion provided on the other.

[0064] The tread member 13 is formed into a cylindrical shape, and covers the outer peripheral surface side of the outer cylinder 32 of the ring member 12 within the range of the entire area. The tread 13a of the non-pneumatic tire 1 is formed by the outer peripheral surface of the tread member 13. In the present embodiment, the tread member 13 is formed by, for example, vulcanized rubber or thermoplastic material formed by vulcanizing a rubber composition containing natural rubber, etc. As thermoplastic materials, for example, thermoplastic elastomers, thermoplastic resins, etc. can be listed. As thermoplastic elastomers, for example, amide thermoplastic elastomers (TPA) specified in JIS K 6418, ester thermoplastic elastomers (TPC), olefin thermoplastic elastomers (TPO), styrene thermoplastic elastomers (TPS), polyurethane thermoplastic elastomers (TPU), thermoplastic rubber crosslinked bodies (TPV), other thermoplastic elastomers (TPZ), etc. can be listed. As thermoplastic resins, for example, polyurethane resins, olefin resins, vinyl chloride resins, polyamide resins, etc. can be listed.

[0065] In addition, from the viewpoint of wear resistance, it is preferable to form the tread member 13 from vulcanized rubber.

[0066] Next, the forming die 100 used in the method for manufacturing the non-pneumatic tire 1 according to the present embodiment will be described.

[0067] like Figure 2 As shown, the molding die 100 is divided into two parts by a parting line PL, and includes a fixed side die 110 on the right side of the figure and a movable side die 130 that can move in the left-right direction of the figure relative to the fixed side die 110. Figure 2 The fixed mold 110 and the movable mold 130 are shown in a state where the molds are butted against each other at the parting line PL.

[0068] The tread member 13 is arranged in the cavity 102 formed by the fixed side mold 110 and the movable side mold 130. Before closing the molding die 100, the person performing the manufacturing method arranges the tread member 13 in the cavity 102. As described later, the width of the tread member 13 in the tire width direction A before insert molding is larger than the width of the cavity 102 in the tire width direction A of the molding die 100 after the mold is closed. That is, in the case of Figure 1A In the state where the tread member 13 is arranged in the mold cavity 102 and the mold is closed, the tread member 13 is compressed in the tire width direction A from the molding die 100. As a result, it is possible to suppress the molten resin R supplied into the mold cavity 102 through the gate 104 from leaking upward from the gap between the both ends of the tread member 13 in the tire width direction A and the mold cavity 102.

[0069] exist Figure 2 , from the fixed side mold 110 toward the movable side mold 130 side ( Figure 1AThe fixed side stopper member 112 for forming the connecting member 33 is protrudingly provided on the left side of the movable side mold 130. Similarly, from the movable side mold 130 toward the fixed side mold 110 side ( Figure 1A The movable side stopper member 132 for forming the connecting member 33 is protrudingly provided on the right side of the fixing member 112. In the example shown in the figure, the movable side stopper member 132 is arranged at a radial position between the two fixed side stopper members 112. The fixed side stopper member 112 and the movable side stopper member 132 are formed at Figure 1A The non-pneumatic tire 1 shown has a hole portion 33 c between the connecting members 33 adjacent in the circumferential direction.

[0070] Figure 2 The arrangement of the fixed side stopper member 112 and the movable side stopper member 132 in the cross-sectional view of the forming die 100 is similar to Figure 1A and Figure 1B The cross section II of the non-pneumatic tire 1 in FIG. Figure 2 The outer side of the tire radial direction B ( Figure 2 The height of the fixed side block member 112 in the tire radial direction B is Figure 1B The radial length r1 on the section I-I in corresponds to. Similarly, Figure 2 The height of the movable side stopper member 132 in the tire radial direction B is Figure 1B The radial length r2 on the section I-I in corresponds to. In addition, Figure 2 Inner side of tire radial direction B ( Figure 2 The height of the fixed side block member 112 in the tire radial direction B is Figure 1B It corresponds to the radial length r3 on the section II in FIG.

[0071] like Figure 2 and Figure 3 As shown, the fixed side stopper member 112 is provided with a mold opening slope in which the height in the tire radial direction B and the width in the tire circumferential direction C decrease from the base end portion 112b toward the top end portion 112a. According to this structure, it is easier to release the non-pneumatic tire 1 from the forming mold 100 when the mold is opened. In addition, it is possible to suppress the situation in which the stopper member 112 collides with the inner peripheral surface of the tread member 13 when the forming mold 100 is closed.

[0072] Utilizing the above-mentioned mold opening inclination, in the state before the embedded forming ring member 12, the tire radial position B of the inner circumferential surface at the end position A in the tire width direction of the tread member 13 is the same radial position as the radial outermost end at the end position A in the tire width direction of the fixed side stopper member 112 forming the connecting member 33 (the base end 112b at the tire radial position B which is farthest from the center).

[0073] That is, before being inserted into the molding ring member 12, the inner peripheral surface of the end portion of the tread member 13 on the fixed side mold 110 abuts against the thickest base end portion 112b of the fixed side stopper member 112. According to this structure, since the tread member 13 is held by the fixed side stopper member 112 before being inserted into the molding ring member 12, it is not easy for the tread member 13 to be displaced due to the supply of the molten resin R as a later step, and the molding ring member 12 can be stably inserted into the molding ring member 12.

[0074] In addition, if Figure 3 As shown, since the fixed side block member 112 and the movable side block member 132 are arranged alternately in the circumferential direction, in the state before the embedded molding ring member 12, the tread member 13 is alternately supported in the circumferential direction by the base end portion 112b of the fixed side block member 112 and the base end portion 132b of the movable side block member 132.

[0075] like Figure 2 As shown, in the state before the ring member 12 is inserted and molded, the outer diameter of the outer peripheral surface (tread 13a) of the tread member 13 is smaller than the inner diameter of the inner peripheral surface 102a of the cavity 102 opposite to the outer peripheral surface. According to this structure, when the pressurized molten resin R is supplied into the cavity 102 through the gate 104 as described later, the tread 13a of the tread member 13 expands toward the outer side of the tire radial direction B in a manner close to the inner peripheral surface 102a of the cavity 102 opposite to the tread 13a. Afterwards, although the filled molten resin R shrinks when cooled, the tread member 13 that expands toward the outer side of the tire radial direction B returns to its original shape following the shrinkage of the resin. Therefore, it is possible to prevent the inner peripheral surface of the tread member 13 and the shrinking resin (ring member 12) from being easily peeled off.

[0076] In use with Figure 2 and Figure 3 When the method for manufacturing the non-pneumatic tire 1 of the present embodiment is implemented by using the molding die 100 having a structure of Figure 4 Step S101) In order to insert the tread member 13 into the forming mold 100, the movable side mold 130 is moved toward Figure 2 The mold cavity 102 is opened by moving to the left side of the mold 100, and the tread member 13 is inserted into the mold cavity 102 of either the fixed mold 110 or the movable mold 130. As described above, since the tire width direction A end of the inner circumferential surface of the tread member 13 is supported by the base end 112b of the fixed side stopper member 112 or the base end 132b of the movable side stopper member 132, it is stably held in the fixed mold 110 or the movable mold 130 when the molding mold 100 is opened.

[0077] Next, the movable mold 130 is moved toward the fixed mold 110 to close the molds, and the tread member 13 is compressed in the tire width direction A ( Figure 4 As described above, the width of the tread member 13 of the ring member 12 before molding in the tire width direction A is formed to be larger than the length of the cavity 102 of the molding die 100 in the tire width direction A. Figure 5 As shown, in a state where the fixed side mold 110 and the movable side mold 130 are separated by a gap G, both ends of the tread member 13 in the tire width direction A abut against both ends of the mold cavity 102 in the tire width direction A of the forming mold 100. Figure 5 The state shown makes the movable side mold 130 closer to the fixed side mold 110, so that the tread member 13 is compressed by the tire width direction A both ends of the mold cavity 102, and the tire width direction A both ends of the tread member 13 and the mold cavity 102 are sealed ( Figure 2 In addition, in this embodiment, Figure 5 As shown, the gate 104 is arranged so that the parting line PL passes through the axis of the gate 104 for supplying the molten resin R into the cavity 102 .

[0078] Next, molten resin R ( Figure 4 The supply of molten resin R is as follows: Figure 6 As shown in FIG. 1 , the molten resin R is pressurized and fed into the cavity 102 through a gate 140 provided on the inner side of the cavity 102 in the tire radial direction B. As for the supplied molten resin R, first, Figure 6 The fixed side block member 112 on the inner side of the tire radial direction B (the lower side of the figure) is close to the inner side of the tire radial direction B and the inner cylinder 31 (refer to Figure 1A ) into the space corresponding to the molten resin R. Figure 6 The direction of the arrow (outer direction of the tire radial direction B, Figure 6 The molten resin R is sequentially supplied to the upper direction of Figure 1A The molten resin R is supplied into the space corresponding to the connecting member 33. Figure 1A The molten resin R is supplied into a space corresponding to the outer cylindrical body 32 and facing the inner peripheral surface of the tread member 13 .

[0079] When the molten resin R is filled in the space in the mold cavity 102 facing the inner peripheral surface of the tread member 13, as shown in FIG. Figure 7 As shown, the tread member 13 is pressurized by the molten resin R and expands outward in the tire radial direction B ( Figure 4Step S104). The tread member 13 expands until the tread 13a contacts the inner circumferential surface 102a in the mold cavity 102, and a compressive strain is generated in the tire radial direction B due to the further pressure of the molten resin R. As a result, a strain that also extends in the tire width direction A is generated, so that the two ends of the tread member 13 in the tire width direction A and the two ends of the mold cavity 102 in the tire width direction A are more firmly fitted, and the sealing between the two is improved. Therefore, it is possible to effectively prevent the molten resin R from leaking outward from the tire radial direction B through the two ends of the tread member 13 in the tire width direction A.

[0080] When the pressurized molten resin R is filled into the cavity 102 in step S104, the supply of the molten resin R from the gate 104 is stopped, and the molten resin R in the cavity 102 is cooled. The pressure in the cavity 102 decreases during the cooling of the molten resin R, and the molten resin R shrinks based on the inherent molding shrinkage of the material. Although the cooled resin in the cavity 102 shrinks toward the inner side of the tire radial direction B, the tread member 13 expanded toward the outer side of the tire radial direction B in step S104 returns to its original shape before the supply of the molten resin R due to the decrease in the resin pressure in the cavity 102. The tread member 13 shrinks toward the inner side of the tire radial direction B in the same manner as the cooled resin.

[0081] In particular, in the present embodiment, the shrinkage rate of the tread member 13 as the molten resin R cools is larger than the shrinkage rate of the molten resin R (ring member 12) on the radially inner side of the tread member 13. Here, the shrinkage rate of the tread member 13 is the diameter of the inner peripheral surface on the inner side of the tire radial direction B of the tread member 13 inserted into the molding die 100 relative to the state in which the tread member 13 is expanded toward the outer side of the tire radial direction B when the pressurized molten resin R is supplied ( Figure 7 The shrinkage rate of the molten resin R (ring member 12) on the radially inner side of the tread member 13 is the reduction in the diameter of the outer peripheral surface of the molten resin R (ring member 12) on the outer side of the tire radial direction B in the state where the molten resin R is cooled relative to the state where the pressurized molten resin R is supplied ( Figure 7 The reduction in diameter of the outer peripheral surface under the condition of (in the state).

[0082] Thus, in the present embodiment, the shrinkage rate of the tread member 13 as the molten resin R is cooled is configured to be greater than the shrinkage rate of the molten resin R (ring member 12) on the radially inner side of the tread member 13. According to this configuration, when the molten resin R is cooled, the inner peripheral surface of the tread member 13 on the inner side of the tire radial direction B shrinks more toward the inner side of the tire radial direction B than the outer peripheral surface of the ring member 12 on the outer side of the tire radial direction B. Therefore, it is possible to effectively suppress the outer peripheral surface of the ring member 12 from peeling off from the inner peripheral surface of the tread member 13.

[0083] Figure 8 is a modified example of this embodiment, which is Figure 7 An enlarged view of the state in which the corresponding molten resin R is filled in the mold cavity 102. In this modified example, a fitting groove 102b is provided to accommodate a protrusion 13b that further protrudes outward from the end of the tread member 13 in the tire width direction A. According to this structure, the sealing between the end of the tread member 13 in the tire width direction A and the mold cavity 102 can be further improved to effectively suppress the molten resin R from leaking outward in the tire radial direction B. In addition, by making the protrusion 13b protrude slightly more than the ring member 12 formed by the molten resin R in the tire width direction A, it is possible to suppress the resin ring member 12 from directly colliding with other objects and being broken or damaged.

[0084] As described above, the present embodiment is a method for manufacturing a non-pneumatic tire 1, the non-pneumatic tire 1 comprising: a ring member 12 integrally formed with an inner cylinder 31, an outer cylinder 32 surrounding the inner cylinder 31 from the outer side of the tire radial direction B, and an elastically deformable connecting member 33 connecting the inner cylinder 31 and the outer cylinder 32 to each other; and a cylindrical tread member 13 mounted on the outer side of the ring member 12 in the tire radial direction B. In the manufacturing method, the following steps are included: The tread member 13 is inserted into the cavity 102 of the mold 100; the movable side mold 130 is moved toward the fixed side mold 110 to close the cavity 102; and the molten resin R is supplied to the space inside the tire radial direction B of the tread member 13 in the cavity 102 to form the ring member 12. In this manufacturing method, the outer diameter of the outer peripheral surface (tread 13a) of the tread member 13 before the ring member 12 is formed is smaller than the inner diameter of the inner peripheral surface 102a of the cavity 102 opposite to the outer peripheral surface. By adopting such a structure, when the pressurized molten resin R is supplied into the cavity 102, the tread 13a of the tread member 13 expands toward the outer side of the tire radial direction B so as to approach the inner peripheral surface 102a of the cavity 102 opposite to the tread 13a. Thereafter, although the filled molten resin R shrinks when cooled, the tread member 13 expanded toward the outer side of the tire radial direction B returns to its original shape following the shrinkage of the resin. Therefore, it is possible to prevent the inner peripheral surface of the tread member 13 and the shrunk resin (ring member 12) from being easily separated from each other.

[0085] In addition, in the present embodiment, the shrinkage rate of the tread member 13 as the molten resin R is cooled is larger than the shrinkage rate of the ring member 12. By adopting such a structure, when the molten resin R is cooled, the inner peripheral surface of the tread member 13 on the inner side of the tire radial direction B shrinks to a greater extent to the inner side of the tire radial direction B than the outer peripheral surface of the ring member 12 on the outer side of the tire radial direction B. Therefore, a force is applied in a direction to make the outer peripheral surface of the ring member 12 and the inner peripheral surface of the tread member 13 close to each other, so that the outer peripheral surface of the ring member 12 can be effectively suppressed from peeling off from the inner peripheral surface of the tread member 13. In addition, in the present embodiment, it is set as follows: the shrinkage rate of the tread member 13 and the ring member 12 is changed to prevent the outer peripheral surface of the ring member 12 from peeling off from the inner peripheral surface of the tread member 13, but it is not limited to this state. It is also possible to actively seek to prevent the tread member 13 from peeling off from the ring member 12 by appropriately using an adhesive or the like or by using a method of bonding a resin subjected to surface treatment and a vulcanized rubber subjected to surface treatment without the aid of an adhesive.

[0086] In addition, in the present embodiment, the radial position of the inner peripheral surface of the tread member 13 at the end position in the tire width direction A before the ring member 12 is formed is the same radial position as the outermost end in the tire radial direction B at the end position in the tire width direction A of the stopper members (fixed side stopper member 112 and movable side stopper member 132) forming the connecting member 33 of the forming mold 100. By adopting such a configuration, since the inner peripheral surface of the tread member 13 is supported by the stopper members of the forming mold 100 in the entire circumferential direction, it is not easy to cause the tread member 13 to be displaced due to the supply of the molten resin R, and the ring member 12 can be stably inserted and formed.

[0087] Furthermore, in the present embodiment, the width of the tread member 13 in the tire width direction A before the ring member 12 is formed is configured to be larger than the length of the cavity 102 in the tire width direction A of the forming mold 100. By adopting such a configuration, the two ends of the tread member 13 in the tire width direction A and the cavity 102 are effectively sealed. Therefore, it is possible to effectively suppress the molten resin R from leaking outwardly in the tire radial direction B through the two ends of the tread member 13 in the tire width direction A.

[0088] In addition, in the present embodiment, the stopper members (fixed side stopper member 112 and movable side stopper member 132) of the forming mold 100 are provided with a mold opening slope, which extends from one split mold to the other split mold of the forming mold 100, and is configured so that the top end of the stopper member is thinner than the base end. By adopting such a configuration, it is possible to suppress the situation where the stopper member collides with the inner peripheral surface of the tread member 13 when the forming mold 100 is closed.

[0089] In addition, in the present embodiment, the molding die 100 is configured to have an engagement groove 102b for accommodating the protrusion 13b at the tire width direction end of the tread member 13. By adopting such a configuration, the sealing performance between the tire width direction A end of the tread member 13 and the mold cavity 102 can be further improved, and the molten resin R can be effectively prevented from leaking outward in the tire radial direction B. In addition, by making the protrusion 13b slightly protrude in the tire width direction A from the ring member 12 formed of the molten resin R, it is possible to prevent the resin ring member 12 from directly colliding with other objects and being broken or damaged.

[0090] The present disclosure is described based on the drawings and embodiments, but it should be noted that if a person skilled in the art can make various deformations and modifications based on the present disclosure. Therefore, it should be noted that these deformations and modifications are included in the scope of the present invention. For example, the structure or function included in each embodiment can be reconfigured without theoretical contradiction. In addition, the structure or function included in each embodiment can be used in combination with other embodiments, and multiple structures or functions can be combined into one, or divided, or a part can be omitted.

[0091] For example, the present embodiment is assumed to be used for manufacturing a bottom load type non-pneumatic tire 1 , but is not limited to this aspect and can also be used for manufacturing a top load type non-pneumatic tire 1 .

[0092] Industrial Applicability

[0093] The present disclosure relates to a method for manufacturing a non-pneumatic tire 1 capable of suppressing separation of a ring member 12 from a tread member 13 .

[0094] Description of Reference Numerals

[0095] 1. non-pneumatic tire; 11. mounting body; 12. ring member; 13. tread member; 13a. tread; 13b. protrusion; 21. mounting cylinder; 22. outer cylinder; 23. rib; 31. inner cylinder; 32. outer cylinder; 33. connecting member; 33a. connecting plate; 33a1. outer end; 33a2. inner end; 33c. hole; 70. bolt; 100. forming mold; 102. mold cavity; 102a. inner circumferential surface; 102b. fitting groove; 10 4. Gate; 110. Fixed side mold; 112. Fixed side block member; 112a. Top end; 112b. Base end; 130. Movable side mold; 132. Movable side block member; 132a. Top end; 132b. Base end; 140. Gate; 210a. Axle; A. Tire width direction; B. Tire radial direction; C. Tire circumferential direction; G. Gap; O. Center axis; PL. Parting line; R. Molten resin; r1, r2, r3. Radial length.

Claims

1. A method for manufacturing a non-pneumatic tire, the non-pneumatic tire comprising: a ring member integrally formed with an inner cylinder, an outer cylinder surrounding the inner cylinder from the outer side in the tire radial direction, and an elastically deformable connecting member connecting the inner cylinder and the outer cylinder to each other; and a cylindrical tread member mounted on the outer side of the ring member in the tire radial direction, The manufacturing method includes the following steps: inserting the tread member into a mold cavity of a forming mold; Moving the movable side mold toward the fixed side mold to close the mold cavity; and supplying molten resin to a space on the inner side of the tread member in the tire radial direction in the mold cavity to mold the ring member, The outer diameter of the outer peripheral surface of the tread member before the ring member is formed is smaller than the inner diameter of the inner peripheral surface of the cavity that faces the outer peripheral surface.

2. The method for manufacturing a non-pneumatic tire according to claim 1, wherein: The shrinkage rate of the tread member as the molten resin is cooled is larger than the shrinkage rate of the ring member.

3. The method for manufacturing a non-pneumatic tire according to claim 1 or 2, wherein: The radial position of the inner circumferential surface of the tread member at the tire width direction end position before forming the ring member is the same radial position as the outermost end in the tire radial direction at the tire width direction end position of the stopper member of the forming mold forming the connecting member.

4. The method for manufacturing a non-pneumatic tire according to claim 1 or 2, wherein: The width of the tread member in the tire width direction before the ring member is formed is greater than the length of the cavity of the forming mold in the tire width direction.

5. The method for manufacturing a non-pneumatic tire according to claim 1 or 2, wherein: The stopper member of the forming mold is provided with a mold opening slope extending from one split mold of the forming mold to the other split mold, and is configured so that the top end portion of the stopper member is thinner than the base end portion.

6. The method for manufacturing a non-pneumatic tire according to claim 1 or 2, wherein: The molding die has a fitting groove for receiving a protrusion at an end portion in the tire width direction of the tread member.

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