Tire molding drum

Abstract

A tire molding drum according to the present disclosure comprises a plurality of segments that are disposed in the drum circumferential direction and form a drum outer peripheral surface where an outer surface in the drum radial direction can support a tire material. The plurality of segments include a partially expanding / contracting segment capable of forming a retreat surface in a portion of the drum outer peripheral surface in the drum circumferential direction by retreating inward in the drum radial direction with respect to an adjacent segment that is adjacent in the drum circumferential direction. The partially expanding / contracting segment includes: a mobile body that is movable in the drum radial direction; and a swing flap that is disposed so as to span the mobile body and the adjacent segment in the drum circumferential direction, and is pivotally supported by the adjacent segment so as to swing in the drum radial direction in conjunction with the movement of the mobile body in the drum radial direction.

Description

tire building drum

[0001] The present disclosure relates to tire building drums.

[0002] A conventional tire building method involves winding a ply around the outer peripheral surface of a tire building drum and joining both end faces of the ply in the circumferential direction of the drum together. Patent Document 1 discloses this type of tire building method.

[0003] Special table 2017-523926 publication

[0004] Incidentally, the ply is wound around the outer peripheral surface of the tire building drum so as to cover other tire materials, such as an inner liner and side rubber, that are already supported on the drum outer peripheral surface. As a result, both ends of the ply in the drum circumferential direction may adhere to the other tire materials, such as the inner liner and side rubber, making it difficult to accurately join both ends of the ply. In contrast, according to the tire building method described in Patent Document 1, a separator is disposed between the ply and other tire materials, such as the inner liner and side rubber, and both ends of the ply in the drum circumferential direction are held on the separator, thereby allowing joining without adhering these both ends to other tire materials, such as the inner liner and side rubber. This improves the joining accuracy of both ends of the ply in the drum circumferential direction.

[0005] However, in the tire building method described in Patent Document 1, the separator is arranged so that it protrudes radially outward from the drum outer peripheral surface, which is perfectly circular when viewed in the drum axial direction. If the ply is wound around the drum outer peripheral surface to cover the separator in this state, excess ply will be formed where the separator is located, and the shape of the ply will not be perfectly circular when viewed in the drum axial direction, which could reduce the circularity of the finished tire.

[0006] An object of the present disclosure is to provide a tire building drum that can improve the roundness of the ply when viewed in the drum axial direction, even when the ply is built using a separator.

[0007] A tire building drum according to a first aspect of the present disclosure is a tire building drum comprising: (1) a plurality of segments arranged in the drum circumferential direction, each segment having a radially outer surface that forms a drum outer peripheral surface capable of supporting a tire material, the plurality of segments including a partial expansion / contraction segment that can form a receding surface on a portion of the drum circumferential surface by receding radially inward relative to an adjacent segment adjacent to the drum circumferential direction, the partial expansion / contraction segment comprising: a movable body that can move in the drum radial direction; and a swinging flap that is arranged between the movable body and the adjacent segment in the drum circumferential direction and is journaled on the adjacent segment so as to swing in the drum radial direction in conjunction with the movement of the movable body in the drum radial direction. This configuration can improve the roundness of the ply as viewed from the drum axial direction, even when the ply is molded using a separator.

[0008] A tire building drum according to one embodiment of the present disclosure is the tire building drum described in (1) above, wherein: (2) the movable body includes a first comb-tooth portion having a plurality of convex portions that protrude in the drum circumferential direction toward the swinging flap and are spaced apart along the drum axial direction, the swinging flap includes a plurality of second comb-tooth portions that protrude in the drum circumferential direction toward the movable body and are spaced apart along the drum axial direction, and the first comb-tooth portion and the second comb-tooth portion are intermeshed with each other. This configuration makes it possible to prevent air from entering between the belt-shaped rubber member and the ply when the partial expansion / contraction segment is advanced outward in the drum radial direction and the belt-shaped rubber member is pressed against the inner surface of the ply in the drum radial direction.

[0009] A tire building drum according to one embodiment of the present disclosure is the tire building drum according to (3) above (1) or (2), wherein the movable body includes a cam groove extending in the drum circumferential direction, and the swinging flap includes a cam protrusion that is housed in the cam groove and is movable in the extension direction of the cam groove in association with the movement of the movable body in the drum radial direction. With this configuration, the swinging flap can be easily swung in conjunction with the movement of the movable body in the drum radial direction.

[0010] A tire building drum according to one embodiment of the present disclosure is (4) the tire building drum according to any one of (1) to (3) above, further comprising a movable body drive unit that can drive the movable body inward in the drum radial direction so as to form the receding surface. With this configuration, by driving the movable body inward in the drum radial direction, the receding surface can be formed on a portion of the drum circumferential surface.

[0011] A tire building drum according to one embodiment of the present disclosure is (5) the tire building drum according to (4) above, further comprising a segment group drive unit that is separate from the movable body drive unit and that is capable of expanding and contracting the plurality of segments in the drum radial direction. With this configuration, the entire circumferential area of ​​the drum outer circumferential surface can be expanded and contracted while maintaining the drum outer circumferential surface in a perfect circular shape.

[0012] A tire building drum according to one embodiment of the present disclosure is (6) the tire building drum according to any one of (1) to (5) above, wherein the movable body is movable inward in the drum radial direction by 20 to 40 mm so as to form the receding surface. With this configuration, it is possible to reliably ensure a space for arranging a separator when forming the receding surface.

[0013] A tire building drum according to one embodiment of the present disclosure is (7) the tire building drum according to any one of (1) to (6) above, wherein the number of the plurality of segments is 8 to 16. This configuration makes it easier to maintain the roundness of the outer peripheral surface of the drum when the plurality of segments as a whole expands and contracts in the drum radial direction.

[0014] According to the present disclosure, it is possible to provide a tire building drum that can improve the roundness of the ply when viewed in the drum axial direction, even when the ply is built using a separator.

[0015] 2B is a diagram showing a state in which a ply is wound around the separator to cover the separator, and both ends of the ply in the drum circumferential direction are held on the separator, with the end faces of both ends of the ply in the drum circumferential direction butting against each other and joined together, while both ends of the ply in the drum circumferential direction are held on the separator. FIG. 2C is a diagram showing a state in which the separator is pulled out from between the ply and the band-shaped rubber member, and the partial expansion / contraction segment is advanced outward in the drum radial direction to integrate the ply and the band-shaped rubber member. FIG. 3A is a diagram showing a tire building drum before the partial expansion / contraction segment is retracted inward in the drum radial direction relative to the adjacent segment. FIG. 3B is a diagram showing a tire building drum in a state in which the partial expansion / contraction segment is retracted inward in the drum radial direction relative to the adjacent segment. FIG. 3A is an enlarged view of a portion of FIG. 3B, and FIG. 3B is an enlarged view of the same position as FIG. 4A. 6A is a plan view of the partial expansion / contraction segment shown in Fig. 1 as seen from the outside in the drum radial direction. Fig. 6B is a perspective view of the moving body shown in Fig. 1. Fig. 6C is a perspective view of the moving body shown in Fig. 1 as seen from a different viewpoint than Fig. 6A. Fig. 6D is a cross-sectional view showing a cross section along the drum axial direction of the tire building drum shown in Fig. 1. Fig. 7A is a cross-sectional view showing a state in which the tire building drum has been contracted in diameter from the state shown in Fig. 7A without forming a receding surface.

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a tire building drum according to the present disclosure will be described with reference to the drawings. In each drawing, the same components are designated by the same reference numerals.

[0017] FIG. 1 is a diagram showing a portion of a tire building drum 1 as one embodiment of a tire building drum according to the present disclosure. Hereinafter, for convenience of explanation, a direction parallel to the central axis O of the tire building drum 1 will be referred to as the "drum axial direction A." Furthermore, a direction around the central axis O of the tire building drum 1 will be referred to as the "drum circumferential direction B." Furthermore, a radial direction of a circle around the central axis O of the tire building drum 1 will be referred to as the "drum radial direction C." Furthermore, the outer surface of the tire building drum 1 in the drum radial direction C will be referred to as the "drum outer peripheral surface 2." The tire building drum 1 is used to build a green tire, which is the base shape of a tire. During the green tire building process using the tire building drum 1, a cylindrical member is formed in which a band-shaped rubber member X and a ply Y, which serve as tire materials, overlap in the drum radial direction C. Examples of the band-shaped rubber member X include an inner liner X1 and a side rubber X2. Examples of the ply Y include a carcass ply formed by coating a reinforcing cord with rubber.

[0018] As will be described in detail later, as shown in Fig. 1, a tire building drum 1 includes a plurality of segments 10 arranged in the drum circumferential direction B. The outer surfaces 5 of the respective segments 10 in the drum radial direction C collectively form the drum outer peripheral surface 2 capable of supporting a tire material.

[0019] The multiple segments 10 include a partial expansion / contraction segment 12 and an adjacent segment 11 adjacent to the partial expansion / contraction segment 12 in the drum circumferential direction B. The partial expansion / contraction segment 12 is retractable inward in the drum radial direction C relative to the adjacent segment 11. By retracting the partial expansion / contraction segment 12 inward in the drum radial direction C relative to the adjacent segment 11, a retracted surface 3 can be formed on a part of the drum outer circumferential surface 2 in the drum circumferential direction B. The partial expansion / contraction segment 12 includes a movable body 20 and a swinging flap 30. The movable body 20 is movable in the drum radial direction C. The swinging flap 30 is disposed across the movable body 20 and the adjacent segment 11 in the drum circumferential direction B. The swinging flap 30 is journaled to the adjacent segment 11 so as to swing in the drum radial direction C in conjunction with the movement of the movable body 20 in the drum radial direction C.

[0020] Next, a tire building method using a tire building drum 1 will be described with reference to FIGS. 2A to 2D . FIG. 2A shows a state in which an inner liner X1 and side rubbers X2, which serve as a band-shaped rubber member X, are supported on the drum outer peripheral surface 2 of the tire building drum 1. FIG. 2B shows a state in which, from the state shown in FIG. 2A , the partial expansion / contraction segment 12 is retracted inward in the drum radial direction C relative to the adjacent segment 11, forming a retracted surface 3 on a part of the drum outer peripheral surface 2 in the drum circumferential direction B, and a separator 80 is disposed in the space formed by forming the retracted surface 3. FIG. 2C shows a state in which, from the state shown in FIG. 2B , a ply Y is wound to cover the separator 80, and both ends of the ply Y in the drum circumferential direction B are held on the separator 80, with the end faces of both ends of the ply Y in the drum circumferential direction B butted against each other and joined together. Figure 2D shows a state in which the separator 80 is pulled out from between the ply Y and the band-shaped rubber member X from the state shown in Figure 2C, and the partial expansion / contraction segment 12 is advanced outward in the drum radial direction C, thereby integrating the ply Y and the band-shaped rubber member X.

[0021] First, an overview of some steps included in the tire building method, as shown in Figures 2A to 2D, will be described. In this tire building method, a rubber member winding process is first performed, in which an inner liner X1 and side rubbers X2, which serve as a band-shaped rubber member X, are wound around the drum outer peripheral surface 2 of a tire building drum 1 (see Figure 2A). This is followed by a drum deformation process, in which the partially expanding / contracting segments 12 are retracted inward in the drum radial direction C relative to the adjacent segments 11, to form a retracted surface 3 on part of the drum outer peripheral surface 2 in the drum circumferential direction B (see Figure 2B). By forming the retracted surface 3, a space is formed outside the retracted surface 3 in the drum radial direction C. This is followed by a separator placement process, in which a separator 80 is placed in the space formed by forming the retracted surface 3 (see Figure 2B). This is followed by a ply winding process, in which a ply Y is wound around the drum outer peripheral surface 2 to cover the band-shaped rubber member X and the separator 80, and both ends of the ply Y in the drum circumferential direction B are held on the separator 80 (see Figure 2C). Thereafter, a joining process is carried out in which both end portions of the ply Y in the drum circumferential direction B are butted against each other and joined together while being held on the separator 80 (see FIG. 2C). Thereafter, the separator 80 is pulled out from between the belt-shaped rubber member X and the ply Y, and the partial expansion / contraction segment 12 is advanced outward in the drum radial direction C to integrate the belt-shaped rubber member X and the ply Y (see FIG. 2D).

[0022] As shown in Fig. 2A , in the rubber member winding step, an inner liner X1 and a side rubber X2 as a belt-shaped rubber member X are wound onto the drum outer peripheral surface 2 of a tire building drum 1 in the order of the inner liner X1 and the side rubber X2 so that they partially overlap in the drum radial direction C. Fig. 2A shows a cross section at a position in the drum axial direction A where the inner liner X1 and the side rubber X2 overlap in the drum radial direction C. By winding the belt-shaped rubber member X onto the drum outer peripheral surface 2 of the tire building drum 1 in this rubber member winding step, the belt-shaped rubber member X is molded into a cylindrical shape.

[0023] 2B , in the drum deformation process, the partial expansion / contraction segment 12 is retracted inward in the drum radial direction C relative to the adjacent segment 11, forming a retracted surface 3 on a part of the drum outer circumferential surface 2 in the drum circumferential direction B. At this time, the band-shaped rubber member X is deformed inward in the drum radial direction C at the position of the retracted surface 3 in the drum circumferential direction B so as to follow the retracted surface 3. In the separator arrangement process, a separator 80 is arranged in the space formed by forming the retracted surface 3, i.e., the space formed by the deformation of the band-shaped rubber member X inward in the drum radial direction C so as to follow the retracted surface 3.

[0024] As shown in Fig. 2C , in the ply winding step, the ply Y is wound around the drum outer peripheral surface 2 so as to cover the outside of the cylindrically molded belt-shaped rubber member X and separator 80 in the drum radial direction C, and both end portions of the ply Y in the drum circumferential direction B are held on the separator 80. Furthermore, as shown in Fig. 2C , in the joining step, a pair of joint rollers 71 of a joining device 70 are brought into contact with both end portions of the ply Y in the drum circumferential direction B, respectively, and each joint roller 71 is moved in the drum axial direction A while being rotated. This draws both end portions of the ply Y in the drum circumferential direction B toward each other, and allows the end faces of these end portions to butt against each other and be joined.

[0025] 2D , in the integration process, the separator 80 is pulled out from between the belt-shaped rubber member X and the ply Y along the drum axial direction A, and the partial expansion / contraction segment 12 is advanced outward in the drum radial direction C to integrate the belt-shaped rubber member X and the ply Y. This allows the belt-shaped rubber member X to be pressed against the inner surface of the ply Y in the drum radial direction C, and the belt-shaped rubber member X and the ply Y to be integrated.

[0026] The tire building drum 1 of this embodiment will be described in further detail below.

[0027] 3A and 3B are explanatory diagrams illustrating a mechanism for forming the receding surface 3 of the tire building drum 1 shown in FIG. 1. Specifically, FIG. 3A is a diagram illustrating the tire building drum 1 before the partial expansion / contraction segment 12 is retracted inward in the drum radial direction C relative to the adjacent segment 11. FIG. 3B is a diagram illustrating the tire building drum 1 in a state in which the partial expansion / contraction segment 12 is retracted inward in the drum radial direction C relative to the adjacent segment 11. Of the multiple segments 10 that form the drum outer circumferential surface 2, FIGS. 3A and 3B illustrate three segments: one partial expansion / contraction segment 12 and a pair of adjacent segments 11 on both sides of it. Hereinafter, for convenience of explanation, the state of the tire building drum 1 shown in FIG. 3A may be referred to as a "state before partial contraction," and the state of the tire building drum 1 shown in FIG. 3B may be referred to as a "state after partial contraction."

[0028] 3A and 3B , the outer peripheral surfaces of the multiple segments 10 collectively form one drum outer peripheral surface 2. As shown in Fig. 3A , the multiple segments 10 of this embodiment form a drum outer peripheral surface 2 that is perfectly circular when viewed from the drum axial direction A in the pre-partial diameter-reduced state. In contrast, as shown in Fig. 3B , the multiple segments 10 of this embodiment form a drum outer peripheral surface 2 that is not perfectly circular when viewed from the drum axial direction A in the post-partial diameter-reduced state. Specifically, the drum outer peripheral surface 2 formed by the multiple segments 10 of this embodiment in the post-partial diameter-reduced state includes a receding surface 3 formed by a portion of the drum circumferential direction B being receded more inward in the drum radial direction C than in the pre-partial diameter-reduced state.

[0029] In this way, by forming the receding surface 3 on the drum outer peripheral surface 2, a space can be formed outside the receding surface 3 in the drum radial direction C. In the separator arrangement step (see FIG. 2B ) described above, the separator 80 is arranged in the space formed by forming the receding surface 3. Therefore, the separator 80 is less likely to protrude outside the drum radial direction C from the drum outer peripheral surface 2 in the pre-partial expansion / contraction state. As a result, when the ply Y is wound so as to cover the outside of the separator 80 in the drum radial direction C in the ply winding step (see FIG. 2C ), excess ply Y is less likely to be generated at the position where the separator 80 is arranged in the drum circumferential direction B, and the shape of the ply Y when viewed from the drum axial direction A can be more easily maintained as a perfect circle.

[0030] As described above, the partial expansion / contraction segment 12 includes the movable body 20 and the swinging flap 30. The outer surfaces of the movable body 20 and the swinging flap 30 of the partial expansion / contraction segment 12 in the drum radial direction C are continuous with each other in the drum circumferential direction B, and form part of the drum outer circumferential surface 2 of the tire building drum 1 in the drum circumferential direction B.

[0031] The swinging flap 30 is pivotally supported by the adjacent segment 11 so as to swing in the drum radial direction C. More specifically, as shown in FIGS. 3A and 3B , the swinging flap 30 of this embodiment includes a connecting portion 36 attached to a hinge mechanism 45 of the adjacent segment 11. The hinge mechanism 45 includes a shaft portion 40 extending in the drum axial direction A and a pressing portion 41 disposed inward in the drum radial direction C and spaced apart from the shaft portion 40. The connecting portion 36 is sandwiched between the shaft portion 40 and the pressing portion 41. The connecting portion 36 is rotatable about the shaft portion 40 while sliding on the shaft portion 40 and the pressing portion 41. In this manner, the swinging flap 30 of this embodiment is rotatable relative to the adjacent segment 11 by the connecting portion 36 rotating about the shaft portion 40 between the shaft portion 40 and the pressing portion 41.

[0032] More specifically, the shaft portion 40 of this embodiment has an outer surface 40a located on the outside in the drum radial direction C, and an inner surface 40b located on the inside in the drum radial direction C. The outer surface 40a of the shaft portion 40 constitutes part of the drum outer peripheral surface 2. The inner surface 40b of the shaft portion 40 is disposed opposite the pressing portion 41. The inner surface 40b of the shaft portion 40 includes a convex curved surface. The outer surface 36a of the connecting portion 36 located on the outside in the drum radial direction C includes a concave curved surface. The convex curved surface of the inner surface 40b of the shaft portion 40 and the concave curved surface of the outer surface 36a of the connecting portion 36 are in slidable contact with each other in the circumferential direction around the shaft portion 40.

[0033] Furthermore, the inner surface 36b of the connecting portion 36 located on the inside in the drum radial direction C includes a convex curved surface that is approximately parallel to the outer surface 36a. The outer surface 41a of the pressing portion 41 located on the outside in the drum radial direction C includes a concave curved surface. The convex curved surface of the inner surface 36b of the connecting portion 36 and the concave curved surface of the outer surface 41a of the pressing portion 41 are in contact with each other and slide against each other when the connecting portion 36 rotates around the shaft portion 40, thereby guiding the rotation of the connecting portion 36 around the shaft portion 40.

[0034] With this configuration, it is possible to restrict movement of the connecting portion 36 in the drum radial direction C and the drum circumferential direction B, while allowing the connecting portion 36 to rotate around the shaft portion 40. In this manner, the swinging flap 30 of this embodiment is pivotally supported by the adjacent segment 11 so as to be swingable in the drum radial direction C.

[0035] As shown in Figures 3A and 3B, the swinging flap 30 swings in the drum radial direction C in conjunction with the movement of the movable body 20 in the drum radial direction C. For example, when the movable body 20 moves inward in the drum radial direction C from the pre-partial contraction state (see Figure 3A), the swinging flap 30 swings inward in the drum radial direction C in conjunction with this (see Figure 3B). As a result, the partial expansion / contraction segment 12 retreats inward in the drum radial direction C relative to the adjacent segment 11, forming a retreating surface 3 in a part of the drum outer circumferential surface 2 in the drum circumferential direction B. In this way, by swinging the swinging flap 30 in addition to the movement of the movable body 20 when forming the retreating surface 3, it is possible to prevent a sudden step from occurring in the drum radial direction C between the retreating surface 3 and the part of the drum outer circumferential surface 2 other than the retreating surface 3, compared to when the retreating surface 3 is formed by simply moving only the movable body 20. This makes it easier to hold the band-shaped rubber member X, which has been wound around the drum outer peripheral surface 2 in advance, along the retreating surface 3 when the retreating surface 3 is formed in the drum deformation step (see FIG. 2B ). As a result, in the subsequent separator placement step (see FIG. 2B ), the band-shaped rubber member X is spaced outward in the drum radial direction C from the retreating surface 3, preventing the placement of the separator 80 from being hindered by the band-shaped rubber member X.

[0036] When the movable body 20 moves outward in the drum radial direction C from the partially contracted state (see FIG. 3B), the swinging flap 30 moves in conjunction with this and swings outward in the drum radial direction C (see FIG. 3A). As a result, the partially expanding / contracting segment 12 advances outward in the drum radial direction C relative to the adjacent segment 11, and the drum outer circumferential surface 2 returns to the perfect circular state it had before the receding surface 3 was formed.

[0037] 3A and 3B , the partial expansion / contraction segment 12 of this embodiment is provided with a pair of swinging flaps 30 on both sides of the movable body 20 in the drum circumferential direction B, but the partial expansion / contraction segment 12 may be provided with only one swinging flap 30 on one side of the movable body 20 in the drum circumferential direction B. However, by providing a pair of swinging flaps 30 on both sides of the movable body 20 in the drum circumferential direction B as in the partial expansion / contraction segment 12 of this embodiment, the belt-shaped rubber member X can be held in a state closer to the receding surface 3 than in the case where only one swinging flap 30 is provided.

[0038] 4A is an enlarged view of portion E in FIG. 3A , showing an enlarged view of the portion of the swinging flap 30 pivotally supported by the adjacent segment 11 in the pre-partial diameter-reduction state. Also, FIG. 4B is an enlarged view of portion F in FIG. 3B , showing an enlarged view of the portion of the swinging flap 30 pivotally supported by the adjacent segment 11 in the post-partial diameter-reduction state. As described above, the swinging flap 30 can swing relative to the adjacent segment 11 by the connecting portion 36 rotating around the shaft portion 40 between the shaft portion 40 and the pressing portion 41. As shown in FIGS. 4A and 4B , when the tire building drum 1 changes from the pre-partial diameter-reduction state to the post-partial diameter-reduction state, the end portion 37 of the connecting portion 36 of the swinging flap 30 in the drum circumferential direction B moves outward in the drum radial direction C. The swinging flap 30 of this embodiment is configured so that, in the post-partial diameter-reducing state, the end 37 of this connecting portion 36 is located inside, in the drum radial direction C, with respect to the outline S defined by the drum outer peripheral surface 2 of the tire building drum 1 in the pre-partial diameter-reducing state. This makes it possible to prevent the band-shaped rubber member X wound around the drum outer peripheral surface 2 from being damaged by the end 37 protruding outward in the drum radial direction C when the tire building drum 1 is put into the post-partial diameter-reducing state in the drum deformation process described above.

[0039] Next, a mechanism by which the oscillating flap 30 oscillates in the drum radial direction C in conjunction with movement of the movable body 20 in the drum radial direction C will be described. As shown in FIGS. 3A and 3B , the movable body 20 of this embodiment includes a cam groove 25 extending along the drum circumferential direction B. The oscillating flap 30 of this embodiment is housed in the cam groove 25 and includes a cam protrusion 35 that is movable in the extension direction of the cam groove 25 as the movable body 20 moves in the drum radial direction C. The movable body 20 and the oscillating flap 30 are connected to each other via the cam groove 25 and the cam protrusion 35. The phrase "extending along the drum circumferential direction B" does not necessarily mean that the cam groove 25 extends parallel to the drum circumferential direction B, but also means that the cam groove 25 extends approximately parallel to the drum circumferential direction B, such as extending in a direction inclined at a predetermined angle or less with respect to the drum circumferential direction B.

[0040] Here, when the movable body 20 is moved inward in the drum radial direction C from the pre-partially contracted state (see FIG. 3A ), the cam groove 25 also moves inward in the drum radial direction C. As a result, a driving force directed inward in the drum radial direction C is transmitted to the cam protrusions 35 housed in the cam grooves 25 via the side walls of the cam grooves 25. As a result, the cam protrusions 35 swing inward in the drum radial direction C while moving in the extension direction of the cam grooves 25 relative to the cam grooves 25. With this movement of the cam protrusions 35, the swinging flaps 30 swing inward in the drum radial direction C. Conversely, when the movable body 20 is moved outward in the drum radial direction C from the post-partially contracted state, the cam grooves 25 also move outward in the drum radial direction C. As a result, a driving force directed outward in the drum radial direction C is transmitted to the cam protrusions 35 housed in the cam grooves 25 via the side walls of the cam grooves 25. As a result, the cam protrusions 35 move outward in the drum radial direction C while moving relative to the cam grooves 25 in the extension direction of the cam grooves 25. With this movement of the cam protrusions 35, the swinging flap 30 swings outward in the drum radial direction C. In other words, by transmitting the driving force of the movable body 20 in the drum radial direction C to the swinging flap 30 via the cam grooves 25 and the cam protrusions 35, the swinging flap 30 of this embodiment can swing in the drum radial direction C in conjunction with the movement of the movable body 20 in the drum radial direction C. In this way, by using the cam grooves 25 and the cam protrusions 35, the swinging flap 30 can be easily swing in conjunction with the movement of the movable body 20 in the drum radial direction C.

[0041] FIG. 5 is a plan view of the partial expansion / contraction segment 12 shown in FIG. 1 as viewed from the outside in the drum radial direction C. FIG. 6A is a perspective view of the movable body 20 shown in FIG. 1. FIG. 6B is a perspective view of the movable body 20 shown in FIG. 1 as viewed from a different perspective than FIG. 6A. As shown in FIGS. 5, 6A, and 6B, the cam groove 25 of this embodiment is configured as a recess recessed in the drum axial direction A. Also, as shown in FIG. 5, the cam protrusion 35 of this embodiment is configured as a protrusion protruding in the drum axial direction A. However, the cam groove 25 and the cam protrusion 35 are not limited to this configuration as long as they are configured to oscillate the oscillating flap 30 in the drum radial direction C in conjunction with movement of the movable body 20 in the drum radial direction C. For example, the cam groove 25 may be a recess recessed in the drum radial direction C, and the cam protrusion 35 may be a protrusion protruding in the drum radial direction C.

[0042] 3A and 3B , the tire building drum 1 of this embodiment includes a movable body drive unit 50 that can drive the movable body 20 inward in the drum radial direction C so as to form the receding surface 3. Furthermore, the movable body drive unit 50 can drive the movable body 20 inward in the drum radial direction C to form the receding surface 3, and then drive the movable body 20 outward in the drum radial direction C to return it to the state it was in before the receding surface 3 was formed. In other words, the movable body 20 of this embodiment can be moved inward and outward in the drum radial direction C by the movable body drive unit 50. Although the movable body drive unit 50 of this embodiment is configured by a cylinder mechanism, the configuration of the movable body drive unit 50 is not particularly limited and may be configured by, for example, a link mechanism, a slide mechanism, or the like.

[0043] It is preferable that the movable body 20 is moved 20 to 40 mm inward in the drum radial direction C from the state before partial diameter reduction (see FIG. 3A) so as to form the receding surface 3. By doing so, it is possible to reliably secure a space for arranging the separator 80 when the receding surface 3 is formed.

[0044] As shown in Fig. 5 , the movable body 20 of this embodiment includes a first comb-tooth portion 21 in which a plurality of convex portions 22 projecting in the drum circumferential direction B toward the swinging flap 30 are arranged at intervals along the drum axial direction A. The swinging flap 30 of this embodiment also includes a second comb-tooth portion 31 in which a plurality of convex portions 32 projecting in the drum circumferential direction B toward the movable body 20 are arranged at intervals along the drum axial direction A. As shown in Fig. 5 , the first comb-tooth portion 21 and the second comb-tooth portion 31 are intermeshed with each other.

[0045] Here, a gap 60 is formed on the drum outer peripheral surface 2 of the tire building drum 1 at a position between the movable body 20 and the swinging flap 30 in the drum circumferential direction B, as a buffer space for swinging of the swinging flap 30. This gap 60 serves as a non-pressure region where the belt-shaped rubber member X is not pressed by the drum outer peripheral surface 2 when the partial expansion / contraction segment 12 is advanced outward in the drum radial direction C and the belt-shaped rubber member X is pressed against the inner surface of the ply Y in the drum radial direction C in the above-mentioned integration process (see FIG. 2D ). Therefore, if this non-pressure region becomes large, there is a risk of air being trapped between the belt-shaped rubber member X and the ply Y, which is known as air infiltration. In contrast, if the first comb-tooth portion 21 and the second comb-tooth portion 31 are configured to mesh with each other as in the present embodiment, the gap 60 on the drum outer peripheral surface 2 can be dispersed to different positions in the drum circumferential direction B, and the maximum length Lm over which the gap 60 extends continuously in a straight line in the drum axial direction A can be reduced. This makes it possible to prevent air from entering the non-pressured area (gap 60).

[0046] FIG. 7A is a cross-sectional view of the tire building drum 1 shown in FIG. 1 taken along the drum axial direction A. FIG. 7B is a cross-sectional view showing a state in which the tire building drum 1 has been reduced in diameter from the state shown in FIG. 7A without forming the receding surface 3. As shown in FIGS. 7A and 7B , the tire building drum 1 of this embodiment includes, in addition to the movable body drive unit 50, a segment group drive unit 55 that can expand and contract the multiple segments 10 as a whole in the drum radial direction C. By including this segment group drive unit 55, the tire building drum 1 of this embodiment can expand and contract the entire area of ​​the drum outer circumferential surface 2 in the drum circumferential direction B while maintaining the drum outer circumferential surface 2 in a perfect circular shape. The number of multiple segments 10 included in the tire building drum 1 is preferably 8 to 16. This makes it easier to maintain the roundness of the drum outer circumferential surface 2 when the multiple segments 10 as a whole are expanded and contracted in the drum radial direction C.

[0047] In this embodiment, the segment group drive unit 55 is configured by a cylinder mechanism, but the configuration of the segment group drive unit 55 is not particularly limited and may be configured by, for example, a link mechanism, a slide mechanism, etc. Also, in this embodiment, the segment group drive unit 55 and the movable body drive unit 50 coexist by being arranged at different positions in the drum axial direction A, but the configuration in which the segment group drive unit 55 and the movable body drive unit 50 coexist is not limited to this.

[0048] The tire building drum according to the present disclosure is not limited to the specific configuration shown in the above-described embodiment, and various modifications, changes, and combinations are possible without departing from the scope of the claims.

[0049] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is thought to be a technology that can contribute to "No. 12: Responsible Consumption and Production" and "No. 13: Take concrete action against climate change."

[0050] The present disclosure relates to tire building drums.

[0051] 1: tire building drum, 2: drum outer peripheral surface, 3: receding surface, 5: outer surface of a plurality of segments in the drum radial direction, 10: segment, 11: adjacent segment, 12: partial expansion / contraction segment, 20: moving body, 21: first comb tooth portion, 22: convex portion, 25: cam groove, 30: swinging flap, 31: second comb tooth portion, 32: convex portion, 35: cam convex portion, 36: connecting portion, 36a: outer surface of connecting portion, 36b: inner surface of connecting portion, 37: end portion of connecting portion, 40: shaft portion, 40a: outer surface of shaft portion, 40b: inner surface of shaft portion, 41: pressing portion, 41a: outer surface of pressing portion, 45: hinge mechanism, 50: moving body drive unit, 55: segment group drive unit 60: Gap formed on the outer peripheral surface of the drum between the moving body and the swinging flap in the drum circumferential direction, 70: Jointing device, 71: Joint roller, 80: Separator, A: Drum axial direction, B: Drum circumferential direction, C: Drum radial direction, Lm: Maximum length that the gap on the outer peripheral surface of the drum extends continuously and straight in the drum axial direction, O: Central axis, S: Outline defined by the outer peripheral surface of the tire building drum in a state before partial diameter reduction, X: Band-shaped rubber member, X1: Inner liner, X2: Side rubber, Y: Ply

Claims

1. A tire building drum comprising a plurality of segments arranged in a drum circumferential direction, the outer surfaces in the drum radial direction forming a drum outer peripheral surface capable of supporting tire material, the plurality of segments including a partial expansion / contraction segment that can form a receding surface on a portion of the drum circumferential direction of the drum outer peripheral surface by receding inward in the drum radial direction relative to an adjacent segment adjacent to the drum circumferential direction, the partial expansion / contraction segment comprising: a movable body that can move in the drum radial direction; and a swinging flap that is arranged across the movable body and the adjacent segment in the drum circumferential direction and is journaled on the adjacent segment so as to swing in the drum radial direction in conjunction with the movement of the movable body in the drum radial direction.

2. A tire building drum as described in claim 1, wherein the movable body has a first comb tooth portion having a plurality of convex portions that protrude in the drum circumferential direction toward the oscillating flap and are arranged at a distance along the drum axial direction, and the oscillating flap has a second comb tooth portion having a plurality of convex portions that protrude in the drum circumferential direction toward the movable body and are arranged at a distance along the drum axial direction, and the first comb tooth portion and the second comb tooth portion are meshed with each other.

3. A tire building drum as claimed in claim 1 or 2, wherein the movable body is provided with a cam groove extending along the drum circumferential direction, and the oscillating flap is accommodated in the cam groove and is provided with a cam protrusion that is movable in the extension direction of the cam groove as the movable body moves in the drum radial direction.

4. A tire building drum as claimed in claim 1 or 2, further comprising a moving body drive unit capable of driving the moving body radially inwardly in the drum so as to form the receding surface.

5. A tire building drum as set forth in claim 4, further comprising a segment group drive section capable of expanding and contracting said plurality of segments in the drum radial direction, separate from said movable body drive section.

6. A tire building drum as set forth in claim 1 or 2, wherein said movable body is capable of moving 20 to 40 mm radially inwardly in said drum so as to form said receding surface.

7. A tire building drum as claimed in claim 1 or 2, wherein the number of said plurality of segments is between 8 and 16.

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