Manufacturing method for non-pneumatic tires

Abstract

To provide a method of manufacturing a non-pneumatic tire capable of suppressing separation of a ring member from a tread member.SOLUTION: A non-pneumatic tire 1 comprises: a ring member 12 having an inner cylindrical body 31, an outer cylindrical body 32 surrounding the inner cylindrical body 31 from the outside in a radial direction, and a connection member 33 that connects the inner cylindrical body 31 and the outer cylindrical body 32; and a cylindrical tread member 13. A method of manufacturing the non-pneumatic tire 1 according to the present disclosure comprises the steps of: inserting the tread member 13 into a cavity 102; moving a movable side mold 130 toward a stationary side mold 110 to close the cavity 102; and supplying a molten resin R to a space inside the tread member 13 in the tire radial direction B to mold the ring member 12. An outer diameter of an outer circumferential surface (a tread surface 13a) of the tread member 13 before molding the ring member 12 becomes smaller than an inner diameter of an inner circumferential surface 102a of the cavity 102 that faces the outer circumferential surface.SELECTED DRAWING: Figure 7

Description

Technical Field

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[0006] , ,

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[0001] The present disclosure relates to a method for manufacturing a non-pneumatic tire.

Background Art

[0002] In recent years, in order to avoid the occurrence of punctures, tires that do not require filling with pressurized air inside (non-pneumatic tires) have been developed. The non-pneumatic tire disclosed in Patent Document 1 includes a mounting body attached to an axle, a ring member having an inner cylindrical body externally mounted on the mounting body and an outer cylindrical body surrounding the inner cylindrical body from the outer side in the tire radial direction, a plurality of connecting members disposed along the tire circumferential direction between the inner cylindrical body and the outer cylindrical body and connecting the inner cylindrical body and the outer cylindrical body so as to be relatively elastically displaceable, and a tread member disposed over the entire outer peripheral surface side of the outer cylindrical body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0007] The object of this disclosure is to provide a method for manufacturing a non-pneumatic tire that can suppress the separation of the ring member from the tread member. [Means for solving the problem]

[0008] To solve the above problems, the method for manufacturing a non-pneumatic tire according to this disclosure is: [1] A method for manufacturing a non-pneumatic tire comprising a ring member integrally formed with an inner cylinder, an outer cylinder surrounding the inner cylinder from the outside in the tire radial direction, and an elastically deformable connecting member connecting the inner cylinder and the outer cylinder, and a cylindrical tread member mounted on the outside of the ring member in the tire radial direction, the method comprising the steps of inserting the tread member into the cavity of a molding die, moving the movable side die toward the fixed side die to close the cavity, and supplying molten resin to the space in the cavity on the inside of the tread member in the tire radial direction to mold the ring member, wherein the outer diameter of the outer circumferential surface of the tread member before molding the ring member is smaller than the inner diameter of the inner circumferential surface of the cavity facing the outer circumferential surface. With this configuration, when pressurized molten resin is supplied into the cavity, the tread surface of the tread member expands outward in the tire radial direction so that it approaches the inner circumferential surface of the cavity opposite the tread surface. Subsequently, as the filled molten resin cools, it shrinks, but the tread member that had expanded outward in the tire radial direction returns to its original shape while following the shrinkage of the resin. Therefore, delamination between the inner circumferential surface of the tread member and the shrunk resin (ring member) is less likely to occur.

[0009] Furthermore, the method for manufacturing a non-pneumatic tire described herein is: [2] In the configuration described in [1] above, it is preferable that the shrinkage rate of the tread member due to the cooling of the molten resin is greater than the shrinkage rate of the ring member. With this configuration, during the cooling of the molten resin, the inner circumferential surface of the tread member on the radial side of the tire tends to contract more inward in the radial direction of the tire than the outer circumferential surface of the ring member on the radial side of the tire. Therefore, a force acts on the outer circumferential surface of the ring member to adhere closely to the inner circumferential surface of the tread member, effectively suppressing the separation of the outer circumferential surface of the ring member from the inner circumferential surface of the tread member.

[0010] Furthermore, the method for manufacturing a non-pneumatic tire described herein is: [3] In the configuration described in [1] or [2] above, it is preferable that the radial position of the inner circumferential surface at the tire width direction end position of the tread member before molding 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 die member of the molding die that forms the connecting member. By adopting this configuration, the inner circumferential surface of the tread member is supported circumferentially by the die's insert member, making it less likely for the tread member to shift position due to the supply of molten resin, and allowing the ring member to be stably insert-molded.

[0011] Furthermore, the method for manufacturing a non-pneumatic tire described herein is: [4] In any of the configurations described in [1] to [3] above, it is preferable that the width of the tread member in the tire width direction before molding the ring member is greater than the length of the cavity of the molding die in the tire width direction. By adopting this configuration, the space between the tread member at both ends in the tire width direction and the cavity is effectively sealed. Therefore, it is possible to effectively suppress the leakage of molten resin from the tread member at both ends in the tire width direction to the radial side of the tire.

[0012] Furthermore, the method for manufacturing a non-pneumatic tire described herein is: [5] In any of the configurations described in [1] to [4] above, it is preferable that the spool member of the molding die extends from one split mold to the other split mold of the molding die, and that the tip of the spool member is configured to be thinner than the base end. By adopting this configuration, it is possible to suppress the collision of the saddle component with the inner circumferential surface of the tread component when clamping the molding die.

[0013] Furthermore, the method for manufacturing a non-pneumatic tire described herein is: [6] In any of the configurations described in [1] to [5] above, it is preferable that the molding die has a fitting groove for receiving the projection at the tire widthwise end of the tread member. By adopting this configuration, the sealing performance between the tire widthwise end of the tread member and the cavity can be further enhanced, effectively suppressing leakage of molten resin outward in the tire radial direction. In addition, by making the protrusions slightly protrude in the tire width direction from the ring member formed by the molten resin, it is possible to suppress damage or scratches to the resin ring member from direct collision with other objects. [Effects of the Invention]

[0014] According to this disclosure, it is possible to provide a method for manufacturing a non-pneumatic tire that can suppress the separation of the ring member from the tread member. [Brief explanation of the drawing]

[0015] [Figure 1A] This is a side view of a non-pneumatic tire manufactured by a non-pneumatic tire manufacturing method according to one embodiment of the present disclosure. [Figure 1B] This is an enlarged view of section II in Figure 1A. [Figure 2] This is a front cross-sectional view of a molding die used in a method for manufacturing a non-pneumatic tire according to one embodiment of the present disclosure. [Figure 3]It is a perspective view of a die member of a molding die used in a method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure. [Figure 4] It is a flowchart showing an implementation procedure of a method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure. [Figure 5] It is a front sectional view showing a state during mold clamping of a molding die used in a method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure. [Figure 6] It is a front sectional view showing a state where filling of molten resin into a molding die used in a method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure has started. [Figure 7] It is a front sectional view showing a state where filling of molten resin into a molding die used in a method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure has been completed. [Figure 8] It is an enlarged sectional view showing a modified example of a tread member and a molding die.

MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, a method for manufacturing a non-pneumatic tire according to the present disclosure will be described with reference to the drawings. The same reference numerals are given to common members and parts in each figure.

[0017] [[ID=2Z]]FIG. 1A shows the configuration of a non-pneumatic tire 1 manufactured by a method for manufacturing a non-pneumatic tire according to an embodiment of the present disclosure.

[0018] As shown in FIG. 1A, the non-pneumatic tire 1 includes a ring member 12 mounted on the outer side in the tire radial direction B of a mounting body 11 attached to an axle 210a, and a cylindrical tread member 13 mounted on the outer side in the tire radial direction B of the ring member 12. The non-pneumatic tire 1 of the present embodiment is a so-called bottom-loaded non-pneumatic tire 1 that mainly supports a load by the ring member 12 below the axle 210a.

[0019] Note: In the original text, there is an unclear "図1Aは" in ID=27 which is corrected to "FIG. 1A shows" in the translation for better English expression. Also, there seems to be a duplicate ID=20 which is likely a mistake in the original, and it is left as it is in the translation for the purpose of following the instruction. If this is not correct, please provide more context or clarify the issue.The mounting body 11 includes a cylindrical mounting cylinder portion 21 to which the tip of the axle 210a is attached, a cylindrical outer circumferential cylinder portion 22 that surrounds the mounting cylinder portion 21 from the outside in the tire radial direction B, and a plurality of ribs 23 that connect the mounting cylinder portion 21 and the outer circumferential cylinder portion 22. The outer circumferential cylinder portion 22 defines a circumferential groove that extends over the entire circumference in the tire circumferential direction C on its outer circumferential surface in the tire radial direction B. By providing the mounting body 11, the ring member 12, including the inner cylinder 31, outer cylinder 32, and connecting member 33, can be easily attached to the axle 210a.

[0020] The ring member 12 comprises an inner cylinder 31, an outer cylinder 32 that surrounds the inner cylinder 31 from the outside in the tire radial direction B, and an elastically deformable connecting member 33 that connects the inner cylinder 31 and the outer cylinder 32 to each other.

[0021] Here, the mounting cylinder portion 21, the outer circumferential cylinder portion 22, the inner cylinder 31, the outer cylinder 32, and the tread member 13 are arranged so that their respective central axes are coaxial (share a common central axis O). Furthermore, the mounting cylinder portion 21, the outer circumferential cylinder portion 22, the inner cylinder 31, the outer cylinder 32, and the tread member 13 are arranged so that their central portions in the tire width direction A coincide with each other.

[0022] The mounting cylinder portion 21, the outer circumferential cylinder portion 22, and the ribs 23 of the mounting body 11 are integrally formed from a metal material such as aluminum alloy or a resin material such as polypropylene. The multiple ribs 23 are arranged so as to be point-symmetric with respect to the central axis O in the side view shown in Figure 2.

[0023] Of the ring members 12, the outer cylinder 32 has a larger size in the tire width direction A, i.e., a larger width, than the inner cylinder 31.

[0024] 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 between the inner cylinder 31 and the outer cylinder 32 of the ring member 12 so as to be point-symmetric with respect to the central axis O. Furthermore, each connecting plate portion 33a in this embodiment has the same size and shape. Moreover, the width A in the tire width direction of each connecting plate portion 33a in this embodiment is smaller than the width A in the tire width direction of the outer cylinder 32.

[0025] The connecting plate portions 33a adjacent to each other in the tire circumferential direction C are arranged to be separated from each other and not in contact with each other.

[0026] Of the connecting plate portions 33a, the outer end portion 33a1, which is connected to the outer cylinder 32 and is on the outside in the tire radial direction B, is located on one side in the tire circumferential direction C than the inner end portion 33a2, which is connected to the inner cylinder 31 and is on the inside in the tire radial direction B. In other words, the outer end portion 33a1 and the inner end portion 33a2 are positioned at different locations 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.

[0027] In this embodiment, the inner cylinder 31, outer cylinder 32, and connecting member 33 are made of resin. This makes it possible to reduce the weight of the inner cylinder 31, outer cylinder 32, and connecting member 33. In this embodiment, the inner cylinder 31, outer cylinder 32, and connecting member 33 are integrally formed from resin material by insert molding with the tread member 13 as the insert material. The resin material may be, for example, a single type of resin material, a mixture containing two or more types of resin materials, or a mixture containing one or more types of resin materials and one or more types of elastomers. Furthermore, it may contain additives such as antioxidants, plasticizers, fillers, or pigments. The resin material is preferably a thermoplastic resin.

[0028] Specifically, the resin material can be thermoplastic resins such as polyester and nylon, thermosetting resins such as vinyl ester resins and unsaturated polyester resins, and other synthetic resins. The resin material may further contain reinforcing fibers such as glass, carbon, graphite, aramid, polyethylene, and ceramic.

[0029] In this embodiment, the ring member 12 is composed of the inner cylinder 31, outer cylinder 32, and connecting member 33 described above, but it may also be a ring member comprising other parts.

[0030] The ring member 12 is restricted from relative movement in the tire width direction A relative to the mounting body 11 by housing its inner cylinder 31 within a circumferential groove defined on the outer circumferential surface of the outer circumferential cylindrical portion 22 of the mounting body 11 in the tire radial direction B. Furthermore, 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 circumferential cylindrical portion 22 of the mounting body 11 together with bolts 70. In this way, the ring member 12 in this embodiment is fixed to the mounting body 11, but the fixing of the mounting body 11 and the ring member 12 is not limited to the fixing means described above. Relative movement of the mounting body 11 and the ring member 12 in the tire circumferential direction C may be restricted, for example, by fitting a convex portion provided on one of the outer circumferential surfaces of the outer circumferential cylindrical portion 22 of the mounting body 11 and a concave portion provided on the other.

[0031] The tread member 13 is formed in a cylindrical shape and covers the entire outer surface of the outer cylinder 32 of the ring member 12. The outer surface of the tread member 13 constitutes the tread surface 13a of the non-pneumatic tire 1. In this embodiment, the tread member 13 is formed of vulcanized rubber, which is obtained by vulcanizing a rubber composition including natural rubber, or a thermoplastic material. Examples of thermoplastic materials include thermoplastic elastomers and thermoplastic resins. Examples of thermoplastic elastomers include amide-based thermoplastic elastomers (TPA), ester-based thermoplastic elastomers (TPC), olefin-based thermoplastic elastomers (TPO), styrene-based thermoplastic elastomers (TPS), urethane-based thermoplastic elastomers (TPU), thermoplastic rubber crosslinked material (TPV), and other thermoplastic elastomers (TPZ) as specified in JIS K 6418. Examples of thermoplastic resins include urethane resin, olefin resin, vinyl chloride resin, and polyamide resin.

[0032] Furthermore, from the viewpoint of wear resistance, it is preferable to form the tread member 13 from vulcanized rubber.

[0033] Next, the molding die 100 used in the manufacturing method of the non-pneumatic tire 1 according to this embodiment will be described.

[0034] As shown in Figure 2, the molding die 100 is divided into two parts by a parting line PL, and comprises 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 relative to the fixed-side die 110. Figure 2 shows the state in which the fixed-side die 110 and the movable-side die 130 are in contact with each other at the parting line PL and clamped together.

[0035] A tread member 13 is placed inside the cavity 102 formed by the fixed mold 110 and the movable mold 130. The tread member 13 is placed inside the cavity 102 by the person performing this manufacturing method before the molding die 100 is closed. The width of the tread member 13 in the tire width direction A before insert molding is configured to be larger than the width of the cavity 102 in the tire width direction A of the molding die 100 after the die is closed, as will be described later. In other words, as shown in Figure 1A, when the tread member 13 is placed inside the cavity 102 and the die is closed, the tread member 13 is compressed in the tire width direction A from the molding die 100. This prevents the molten resin R supplied into the cavity 102 through the gate 104 from leaking upward through the gap between both ends of the tread member 13 in the tire width direction A and the cavity 102.

[0036] In Figure 2, a fixed-side sprocket member 112 is provided projecting from the fixed-side mold 110 toward the movable-side mold 130 (left side in Figure 1A) for forming the connecting member 33. Similarly, a movable-side sprocket member 132 is provided projecting from the movable-side mold 130 toward the fixed-side mold 110 (right side in Figure 1A) for forming the connecting member 33. In the illustrated example, the movable-side sprocket member 132 is positioned radially between the two fixed-side sprocket members 112. The fixed-side sprocket member 112 and the movable-side sprocket member 132 form a hole 33c between adjacent connecting members 33 in the circumferential direction of the non-pneumatic tire 1 shown in Figure 1A.

[0037] The arrangement of the fixed-side spool member 112 and the movable-side spool member 132 in the cross-sectional view of the molding die 100 in Figure 2 corresponds to the cross-section II of the non-pneumatic tire 1 in Figures 1A and 1B. Specifically, the height of the fixed-side spool member 112 on the outer side of the tire radial direction B (upper side in Figure 2) corresponds to the radial length r1 on the cross-section II in Figure 1B. Similarly, the height of the movable-side spool member 132 on the tire radial direction B in Figure 2 corresponds to the radial length r2 on the cross-section II in Figure 1B. Furthermore, the height of the fixed-side spool member 112 on the inner side of the tire radial direction B (lower side in Figure 2) corresponds to the radial length r3 on the cross-section II in Figure 1B.

[0038] As shown in Figures 2 and 3, the fixed-side saddle member 112 is provided with a draft angle such that the height B in the tire radial direction and the width C in the tire circumferential direction decrease from the base end 112b to the tip end 112a. This configuration facilitates the release of the non-pneumatic tire 1 from the molding die 100 when the mold is opened. It also prevents the saddle member from colliding with the inner circumferential surface of the tread member 13 when the molding die 100 is clamped.

[0039] Due to the draft angle described above, in the state before insert molding the ring member 12, the position B in the tire radial direction of the inner circumferential surface at the end A in the tire width direction of the tread member 13 is at the same radial position as the outermost radial end (the base end 112b where the tire radial position B is furthest from the center) at the end A in the tire width direction of the fixed side saddle member 112 that forms the connecting member 33.

[0040] In other words, before insert molding the ring member 12, the inner circumferential surface of the end of the tread member 13 on the fixed side mold 110 is in contact with the widest base end 112b of the fixed side spool member 112. With this configuration, before insert molding the ring member 12, the tread member 13 is held by the fixed side spool member 112, making it less likely for the tread member 13 to shift position due to the subsequent supply of molten resin R, and allowing the ring member 12 to be stably insert molded.

[0041] As shown in Figure 3, since the fixed-side link member 112 and the movable-side link member 132 are arranged alternately in the circumferential direction, the tread member 13 is alternately supported in the circumferential direction by the base end 112b of the fixed-side link member 112 and the base end 132b of the movable-side link member 132, before the ring member 12 is insert-molded.

[0042] As shown in Figure 2, in the state before insert molding the ring member 12, the outer diameter of the outer circumferential surface (tread surface 13a) of the tread member 13 is configured to be smaller than the inner diameter of the inner circumferential surface 102a of the cavity 102 facing the outer circumferential surface. With this configuration, when the molten resin R, which is pressurized via the gate 104 as described later, is supplied into the cavity 102, the tread surface 13a of the tread member 13 expands outward in the tire radial direction B so that it approaches the inner circumferential surface 102a of the cavity 102 facing the tread surface 13a. Subsequently, when the filled molten resin R cools, it contracts, but the tread member 13, which had expanded outward in the tire radial direction B, returns to its original shape while following the contraction of the resin. Therefore, delamination between the inner circumferential surface of the tread member 13 and the contracted resin (ring member 12) is less likely to occur.

[0043] When carrying out the manufacturing method of the non-pneumatic tire 1 according to this embodiment using a molding die 100 having the configurations shown in Figures 2 and 3, first, the tread member 13 is inserted into the cavity 102 of the molding die 100 (step S101 in Figure 4). To insert the tread member 13 into the molding die 100, the movable side mold 130 is moved to the left side in Figure 2 to open the cavity 102, and the tread member 13 is inserted into the cavity 102 of either the fixed side mold 110 or the movable side mold 130. As described above, since the A end in the tire width direction of the inner circumferential surface of the tread member 13 is supported by the base end 112b of the fixed side spool member 112 or the base end 132b of the movable side spool member 132, the tread member 13 is stably held in the fixed side mold 110 or the movable side mold 130 when the molding die 100 is open.

[0044] Next, the movable mold 130 is moved toward the fixed mold 110 and clamped, compressing the tread member 13 in the tire width direction A (step S102 in Figure 4). As described above, the width of the tread member 13 in the tire width direction A before molding the ring member 12 is formed to be larger than the length of the cavity 102 of the molding mold 100 in the tire width direction A. Therefore, as shown in Figure 5, when the fixed mold 110 and the movable mold 130 are separated by a gap G, both ends of the tread member 13 in the tire width direction A contact both ends of the cavity 102 of the molding mold 100 in the tire width direction A. By moving the movable mold 130 further toward the fixed mold 110 from this state shown in Figure 5, the tread member 13 is compressed by both ends of the cavity 102 in the tire width direction A, and the space between both ends of the tread member 13 in the tire width direction A and the cavity 102 is sealed (state in Figure 2). In this embodiment, as shown in Figure 5, the gate 104 is positioned such that the parting line PL passes along the axis of the gate 104 that supplies molten resin R into the cavity 102.

[0045] Next, molten resin R is supplied to the space radially inward of the tread member 13 in the cavity 102 (step S103 in Figure 4). As shown in Figure 6, the molten resin R is supplied by pressure into the cavity 102 through a gate 140 provided on the inner side of the cavity 102 in the tire radial direction B. The supplied molten resin R is first supplied to the space corresponding to the inner cylinder 31 (see Figure 1A) which is on the inner side of the tire radial direction B (lower side of the figure) than the fixed side compost member 112. Subsequently, the molten resin R is supplied sequentially in the direction of the arrow in Figure 6 (outward direction of tire radial direction B, upward direction in Figure 6), supplying the molten resin R to the space corresponding to the connecting member 33 in Figure 1A. Finally, the molten resin R is supplied to the space opposite the inner circumferential surface of the tread member 13, which corresponds to the outer cylinder 32 in Figure 1A.

[0046] When the molten resin R fills the space in the cavity 102 facing the inner circumferential surface of the tread member 13, the tread member 13 is pressurized by the molten resin R and expands outward in the tire radial direction B, as shown in Figure 7 (step S104 in Figure 4). The tread member 13 expands until the tread surface 13a contacts the inner circumferential surface 102a within the cavity 102, and further pressure from the molten resin R causes compressive strain in the tire radial direction B. Consequently, strain also tends to occur in the tire width direction A, causing the ends of the tread member 13 in the tire width direction A and the ends of the cavity 102 in the tire width direction A to adhere even more firmly, improving the sealing performance between them. Therefore, leakage of the molten resin R outward in the tire radial direction B through the ends of the tread member 13 in the tire width direction A can be effectively suppressed.

[0047] Once step S104 completes the filling of the cavity 102 with pressurized molten resin R, the supply of molten resin R from the gate 104 is stopped, and the molten resin R in the cavity 102 is cooled. As the molten resin R cools, the pressure in the cavity 102 decreases, and the molten resin R shrinks based on the material's inherent molding shrinkage rate. The cooled resin in the cavity 102 shrinks inward in the tire radial direction B, but because the resin pressure in the cavity 102 has decreased, the tread member 13, which was expanded outward in the tire radial direction B in step S104, returns to its original shape before the supply of molten resin R. The tread member 13 shrinks inward in the tire radial direction B, similar to the cooled resin.

[0048] In particular, in this embodiment, the shrinkage rate of the tread member 13 due to the cooling of the molten resin R 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. Here, the shrinkage rate of the tread member 13 is the decrease in the diameter of the inner circumferential surface of the tread member 13 when inserted into the molding die 100, relative to the diameter of the inner circumferential surface on the radially B side of the tread member 13 when pressurized molten resin R is supplied and the tread member 13 is expanded outward in the tire radial direction B (state shown in Figure 7). Furthermore, the shrinkage rate of the molten resin R (ring member 12) on the radially inner side of the tread member 13 is the decrease in the diameter of the outer circumferential surface of the molten resin R (ring member 12) when the molten resin R has cooled, relative to the diameter of the outer circumferential surface on the radially B side of the molten resin R (ring member 12) when pressurized molten resin R is supplied (state shown in Figure 7).

[0049] Thus, in this embodiment, the shrinkage rate of the tread member 13 due to the cooling of the molten resin R 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. With this configuration, when the molten resin R cools, the inner circumferential surface of the tread member 13 on the radial side B of the tire tends to shrink more inward in the radial direction B than the outer circumferential surface of the ring member 12 on the radial side B of the tire. Therefore, it is possible to effectively suppress the separation of the outer circumferential surface of the ring member 12 from the inner circumferential surface of the tread member 13.

[0050] Figure 8 is a modified example of this embodiment, and is an enlarged view showing the state in which the molten resin R corresponding to Figure 7 is filled into the cavity 102. In this modified example, a fitting groove 102b is provided to receive a projection 13b that protrudes further outward from the end of the tread member 13 in the tire width direction A. This configuration further enhances the sealing performance between the end of the tread member 13 in the tire width direction A and the cavity 102, effectively suppressing leakage of the molten resin R outward in the tire radial direction B. In addition, by making the projection 13b protrude slightly in the tire width direction A than the ring member 12 formed by the molten resin R, it is possible to suppress damage or scratches to the resin ring member 12 from directly colliding with other objects.

[0051] As described above, this embodiment is a method for manufacturing a 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 outside in the tire radial direction B, and an elastically deformable connecting member 33 connecting the inner cylinder 31 and the outer cylinder 32, and a cylindrical tread member 13 mounted on the outside in the tire radial direction B of the ring member 12, the method comprising the steps of inserting the tread member 13 into the cavity 102 of a molding die 100, moving the movable side mold 130 toward the fixed side mold 110 to close the cavity 102, and supplying molten resin R to the space on the inside of the tread member 13 in the tire radial direction B in the cavity 102 to mold the ring member 12, wherein the outer diameter of the outer peripheral surface (tread surface 13a) of the tread member 13 before molding the ring member 12 is configured to be smaller than the inner diameter of the inner peripheral surface 102a of the cavity 102 facing the outer peripheral surface. With this configuration, when pressurized molten resin R is supplied into the cavity 102, the tread surface 13a of the tread member 13 expands outward in the tire radial direction B so that it approaches the inner circumferential surface 102a of the cavity 102 that is opposite to the tread surface 13a. Subsequently, as the filled molten resin R cools, it shrinks, but the tread member 13, which had expanded outward in the tire radial direction B, returns to its original shape while following the shrinkage of the resin. Therefore, delamination between the inner circumferential surface of the tread member 13 and the shrunk resin (ring member 12) is less likely to occur.

[0052] Furthermore, in this embodiment, the shrinkage rate of the tread member 13 due to the cooling of the molten resin R is configured to be greater than the shrinkage rate of the ring member 12. By adopting this configuration, when the molten resin R cools, the inner circumferential surface of the tread member 13 on the inner side in the tire radial direction B tends to shrink more inward in the tire radial direction B than the outer circumferential surface of the ring member 12 on the outer side in the tire radial direction B. Therefore, a force acts in a direction that causes the outer circumferential surface of the ring member 12 to adhere closely to the inner circumferential surface of the tread member 13, so that the separation of the outer circumferential surface of the ring member 12 from the inner circumferential surface of the tread member 13 can be effectively suppressed. In this embodiment, the shrinkage rates of the tread member 13 and the ring member 12 are changed to prevent the separation of the outer circumferential surface of the ring member 12 from the inner circumferential surface of the tread member 13, but the embodiment is not limited to this. The separation of the tread member 13 and the ring member 12 can be actively prevented by using adhesives or by using methods such as bonding a surface-treated resin and a surface-treated vulcanized rubber without using an adhesive.

[0053] Furthermore, in this embodiment, the radial position of the inner circumferential surface of the tread member 13 at the A end position in the tire width direction before molding the ring member 12 is configured to be at the same radial position as the outermost end in the tire radial direction B at the A end position in the tire width direction of the stopper members (fixed stopper member 112 and movable stopper member 132) of the molding die 100 that forms the connecting member 33. By adopting this configuration, the inner circumferential surface of the tread member 13 is supported circumferentially by the stopper members of the molding die 100, so that displacement of the tread member 13 due to the supply of molten resin R is less likely to occur, and the ring member 12 can be stably insert-molded.

[0054] Furthermore, in this embodiment, the width of the tread member 13 in the tire width direction A before molding the ring member 12 is configured to be greater than the length of the cavity 102 of the molding die 100 in the tire width direction A. By adopting this configuration, the space between both ends of the tread member 13 in the tire width direction A and the cavity 102 is effectively sealed. Therefore, it is possible to effectively suppress leakage of molten resin R from both ends of the tread member 13 in the tire width direction A to the outside in the tire radial direction B.

[0055] Furthermore, in this embodiment, the saddle members of the molding die 100 (fixed-side saddle member 112 and movable-side saddle member 132) extend from one split mold to the other of the molding die 100, and are configured to have a draft angle such that the tip of the saddle member is thinner than the base end. By adopting this configuration, it is possible to suppress the saddle members from colliding with the inner circumferential surface of the tread member 13 when the molding die 100 is clamped.

[0056] Furthermore, in this embodiment, the molding die 100 is configured to have a fitting groove 102b that receives the projection 13b at the tire width direction end of the tread member 13. By adopting this configuration, the sealing performance between the tire width direction A end of the tread member 13 and the cavity 102 can be further improved, effectively suppressing leakage of molten resin R to the outside in the tire radial direction B. In addition, by making the projection 13b protrude slightly in the tire width direction A from the ring member 12 formed by the molten resin R, it is possible to suppress damage or scratches to the resin ring member 12 from directly colliding with other objects.

[0057] While this disclosure has been described based on the drawings and embodiments, it should be noted that those skilled in the art can make various modifications and alterations based on this disclosure. Therefore, it should be noted that these modifications and alterations fall within the scope of the present invention. For example, the configurations or functions included in each embodiment can be rearranged in a logically consistent manner. Furthermore, the configurations or functions included in each embodiment can be used in combination with other embodiments, and multiple configurations or functions can be combined into one, divided, or partially omitted.

[0058] For example, this embodiment is intended for use in the manufacture of a bottom-load type non-pneumatic tire 1, but it is not limited to this embodiment and can also be used in the manufacture of a top-load type non-pneumatic tire 1. [Industrial applicability]

[0059] This disclosure relates to a method for manufacturing a non-pneumatic tire 1 that can suppress the separation of the ring member 12 from the tread member 13. [Explanation of Symbols]

[0060] 1: Non-pneumatic tire, 11: Mounting body, 12: Ring member, 13: Tread member, 13a: Tread surface, 13b: Projection, 21: Mounting cylinder part, 22: Outer circumference cylinder part, 23: Rib, 31: Inner cylinder body, 32: Outer cylinder body, 33: Connecting member, 33a: Connecting plate part, 33a1: Outer end, 33a2: Inner end, 33c: Hole, 70: Bolt, 100: Molding die, 102: Cavity, 102a: Inner circumference surface, 102b: Fitting groove, 104: Gate, 110: Fixed side die, 112: Fixed side link member, 112a: Tip part, 112b: Base end, 130: Movable side die, 132: Movable side link member, 132a: Tip, 132b: Base, 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 ring member integrally formed comprising an inner cylinder, an outer cylinder surrounding the inner cylinder from the outside in the tire radial direction, and an elastically deformable connecting member connecting the inner cylinder and the outer cylinder, A cylindrical tread member is mounted on the outer side of the ring member in the tire radial direction, and A method for manufacturing a non-pneumatic tire, comprising: The steps include inserting the tread member into the cavity of the molding die, The steps include moving the movable mold towards the fixed mold to close the cavity, The steps include: supplying molten resin to the space on the inner side of the tread member in the tire radial direction within the cavity to form the ring member; Includes, A method for manufacturing a non-pneumatic tire, wherein the outer diameter of the outer circumferential surface of the tread member before molding the ring member is smaller than the inner diameter of the inner circumferential surface of the cavity facing the outer circumferential surface.

2. The method for manufacturing a non-pneumatic tire according to claim 1, wherein the shrinkage rate of the tread member due to the cooling of the molten resin is greater 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 at the tire width direction end position of the tread member before molding 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 spool member of the molding die that forms the connecting member.

4. A 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 molding the ring member is greater than the length of the cavity of the molding die in the tire width direction.

5. A method for manufacturing a non-pneumatic tire according to claim 1 or 2, wherein the spool member of the molding die extends from one split mold to the other split mold of the molding die, and is provided with a draft angle such that the tip of the spool member is thinner than the base end.

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 projection at the tire widthwise end of the tread member.

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