Tire molding drum

Abstract

To provide a tire molding drum which can easily make a shape of a ply close to a perfect circle when viewed from a drum axial direction, even when a separator is used to mold the ply.SOLUTION: A tire molding drum according to the present disclosure includes a plurality of segments 10 arranged in a drum circumferential direction, an outer surface of which in a drum radial direction forms a drum outer peripheral surface capable of supporting a tire material, and the plurality of segments includes partial expansion / contraction segments that are receded inward in the drum radial direction relative to adjacent segments 11 adjacent to each other in the drum circumferential direction, thereby forming a receding surface in a portion of the drum outer peripheral surface 2 in the drum circumferential direction. The partial expansion / contraction segment includes: a movable body 20 movable in the drum radial direction; and a swinging flap 30 arranged across the movable body and the adjacent segment in the drum circumferential direction and journaled to 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.SELECTED DRAWING: Figure 3B

Description

Technical Field

[0001] The present disclosure relates to a tire building drum.

Background Art

[0002] Conventionally, a tire molding method is known in which a ply is wound along the outer peripheral surface of a drum of a tire building drum, and end faces of both ends of the ply in the drum circumferential direction are abutted against each other and joined. Patent Document 1 discloses this type of tire molding method.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the ply is wound along the outer peripheral surface of the drum so as to cover other tire materials such as an inner liner and side rubber that are previously supported on the outer peripheral surface of the drum of the tire building drum. Therefore, both ends of the ply in the drum circumferential direction may adhere to other tire materials such as the inner liner and side rubber, and it may be difficult to accurately join both ends of the ply. On the other hand, according to the tire molding method described in Patent Document 1, a separator is disposed between other tire materials such as the inner liner and side rubber and the ply, and both ends of the ply in the drum circumferential direction are held on the separator, so that joining can be performed without adhering both ends to other tire materials such as the inner liner and side rubber. Thereby, the joining accuracy of both ends of the ply in the drum circumferential direction can be improved.

[0005] However, in the tire molding method described in Patent Document 1, the separator is arranged so as to protrude outward in the drum radial direction at a part in the drum circumferential direction with respect to the drum outer peripheral surface that is circular when viewed from the drum axis direction. In this state, when the ply is wound along the drum outer peripheral surface so as to cover the separator, the ply becomes surplus at the position where the separator is arranged, and the shape of the ply when viewed from the drum axis direction does not become circular, and there is a risk that the roundness of the finished tire will decrease.

[0006] An object of the present disclosure is to provide a tire molding drum capable of improving the roundness of a ply when viewed from the drum axis direction even when molding the ply using a separator.

Means for Solving the Problems

[0007] A tire molding drum according to a first aspect of the present disclosure is (1) It includes a plurality of segments arranged in the drum circumferential direction and forming a drum outer peripheral surface on whose outer surface in the drum radial direction a tire material can be supported, The plurality of segments include partial expansion and contraction segments capable of forming a retracted surface at a part in the drum circumferential direction of the drum outer peripheral surface by retracting inward in the drum radial direction with respect to adjacent segments adjacent in the drum circumferential direction, The partial expansion and contraction segment is A moving body movable in the drum radial direction, and A swing flap pivotally supported by the adjacent segment so as to be arranged across the moving body and the adjacent segment in the drum circumferential direction and swing in the drum radial direction in conjunction with the movement of the moving body in the drum radial direction. It is a tire molding drum. With this configuration, even when molding the ply using a separator, the roundness of the ply when viewed from the drum axis direction can be improved.

[0008] A tire molding drum according to one embodiment of the present disclosure is (2) The moving body includes a first comb-tooth portion in which a plurality of convex portions protruding in the circumferential direction of the drum toward the swing flap are arranged at intervals along the drum axis direction. The swing flap includes a second comb-tooth portion in which a plurality of convex portions protruding in the circumferential direction of the drum toward the moving body are arranged at intervals along the drum axis direction. The first comb-tooth portion and the second comb-tooth portion are meshed with each other, and the tire molding drum according to (1) above. With this configuration, when the partial expansion and contraction segment advances to the outside in the drum radial direction and presses the belt-like rubber member against the inner surface of the ply in the drum radial direction, it is possible to suppress the generation of air entry between the belt-like rubber member and the ply.

[0009] A tire molding drum as one embodiment of the present disclosure is (3) The moving body includes a cam groove extending along the circumferential direction of the drum. The swing flap is accommodated in the cam groove and includes a cam convex portion that can move in the extending direction of the cam groove as the moving body moves in the drum radial direction. The tire molding drum according to (1) or (2) above. With this configuration, the swing flap can be easily swung in conjunction with the movement of the moving body in the drum radial direction.

[0010] A tire molding drum as one embodiment of the present disclosure is (4) The tire molding drum according to (1) to (3) above, which includes a moving body driving portion capable of driving the moving body inward in the drum radial direction so that the retreat surface is formed. With this configuration, by driving the moving body inward in the drum radial direction, a retreat surface can be formed on a part of the outer peripheral surface of the drum in the circumferential direction of the drum.

[0011] A tire molding drum as one embodiment of the present disclosure is (5) The tire molding drum according to (4) above further includes a segment group driving unit that can expand and contract the plurality of segments in the drum diameter direction, separate from the moving body driving unit. With this configuration, the entire outer peripheral surface of the drum in the circumferential direction of the drum can be expanded and contracted while maintaining the outer peripheral surface of the drum in a perfect circular shape.

[0012] A tire molding drum as one embodiment of the present disclosure is (6) In the tire molding drum according to any one of (1) to (5) above, the moving body is movable 20 to 40 mm inward in the drum diameter direction so that the retreat surface is formed. With this configuration, when forming the retreat surface, a space for arranging the separator can be surely secured.

[0013] A tire molding drum as one embodiment of the present disclosure is (7) In the tire molding drum according to any one of (1) to (6) above, the number of the plurality of segments is 8 to 16. With this configuration, when expanding and contracting the plurality of segments as a whole in the drum diameter direction, it becomes easier to maintain the roundness of the outer peripheral surface of the drum.

Advantages of the Invention

[0014] According to the present disclosure, it is possible to provide a tire molding drum capable of improving the roundness of the ply when the ply is molded using a separator.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 5

Figure 6A

Figure 6B

Figure 7A

Figure 7B

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, embodiments of a tire molding drum according to the present disclosure will be exemplified and described with reference to the drawings. The same components are denoted by the same reference numerals in each figure.

[0017] FIG. 1 is a view showing a part of a tire molding drum 1 as an embodiment of a tire molding drum according to the present disclosure. Hereinafter, for convenience of explanation, the direction parallel to the central axis O of the tire molding drum 1 is referred to as the "drum axial direction A". Also, the direction around the central axis O of the tire molding drum 1 is referred to as the "drum circumferential direction B". Further, the radial direction of the circle around the central axis O of the tire molding drum 1 is referred to as the "drum radial direction C". Also, the outer surface on the drum radial direction C side of the tire molding drum 1 is referred to as the "drum outer peripheral surface 2". The tire molding drum 1 is used for molding a green tire that becomes the prototype of a tire. In the process of molding a green tire by the tire molding drum 1, a cylindrical member is formed in which the belt-like rubber member X and the ply Y as tire materials overlap in the drum radial direction C. Examples of the belt-like rubber member X include an inner liner X1 and a side rubber X2. Examples of the ply Y include a carcass ply formed by covering a reinforcing cord with rubber.

[0018] Although details will be described later, as shown in FIG. 1, the tire molding drum 1 includes a plurality of segments 10 arranged in the drum circumferential direction B. The outer surfaces 5 on the drum radial direction C side of each of the plurality of segments 10 together form a drum outer peripheral surface 2 capable of supporting tire materials.

[0019] The plurality of segments 10 includes 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 with respect to the adjacent segment 11. By the partial expansion / contraction segment 12 retracting inward in the drum radial direction C with respect to the adjacent segment 11, a retracted surface 3 can be formed on a part of the drum circumferential direction B of the drum outer peripheral surface 2. The partial expansion / contraction segment 12 includes a moving body 20 and a swing flap 30. The moving body 20 is movable in the drum radial direction C. The swing flap 30 is disposed across the moving body 20 and the adjacent segment 11 in the drum circumferential direction B. Further, the swing flap 30 is pivotally supported by the adjacent segment 11 so as to swing in the drum radial direction C in conjunction with the movement of the moving body 20 in the drum radial direction C.

[0020] Next, with reference to FIGS. 2A to 2D, a tire molding method performed using the tire molding drum 1 will be described. FIG. 2A is a view showing a state in which an inner liner X1 and a side rubber X2 as a belt-like rubber member X are supported on the drum outer peripheral surface 2 of the tire molding drum 1. FIG. 2B is a view showing 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 with respect to the adjacent segment 11, a retracted surface 3 is formed on a part of the drum circumferential direction B of the drum outer peripheral surface 2, and a separator 80 is disposed in the space formed by forming the retracted surface 3. FIG. 2C is a view showing a state in which, from the state shown in FIG. 2B, a ply Y is wound so as to cover the separator 80, and with both end portions of the ply Y in the drum circumferential direction B held on the separator 80, end faces of both end portions of the ply Y in the drum circumferential direction B are abutted against each other and joined. FIG. 2D is a view showing a state in which, from the state shown in FIG. 2C, the separator 80 is pulled out from between the ply Y and the belt-like rubber member X, and the partial expansion / contraction segment 12 is advanced outward in the drum radial direction C to integrate the ply Y and the belt-like rubber member X.

[0021] First, an overview of some of the steps included in the tire molding method shown in FIGS. 2A to 2D will be described. In this tire molding method, first, a rubber member winding step of winding an inner liner X1 and a side rubber X2 as a strip-shaped rubber member X on the drum outer peripheral surface 2 of the tire molding drum 1 is performed (see FIG. 2A). Then, a drum deformation step of retracting the partial expansion and contraction segment 12 inward in the drum diameter direction C with respect to the adjacent segment 11 to form a retracted surface 3 on a part of the drum circumferential direction B of the drum outer peripheral surface 2 is performed (see FIG. 2B). By forming the retracted surface 3, a space is formed outside the retracted surface 3 in the drum diameter direction C. Then, a separator arranging step of arranging a separator 80 in the space formed by forming the retracted surface 3 is performed (see FIG. 2B). Then, a ply winding step of winding a ply Y along the drum outer peripheral surface 2 so as to cover the strip-shaped rubber member X and the separator 80 and holding both end portions of the ply Y in the drum circumferential direction B on the separator 80 is performed (see FIG. 2C). Then, in a state where both end portions of the ply Y in the drum circumferential direction B are held on the separator 80, a joining step of butting and joining the end surfaces of both end portions to each other is performed (see FIG. 2C). Then, a separating step of pulling out the separator 80 from between the strip-shaped rubber member X and the ply Y and a step of advancing the partial expansion and contraction segment 12 outward in the drum diameter direction C to integrate the strip-shaped rubber member X and the ply Y are performed (see FIG. 2D).

[0022] As shown in FIG. 2A, in the rubber member winding step, the inner liner X1 and the side rubber X2 as the strip-shaped rubber member X are wound on the drum outer peripheral surface 2 of the tire molding drum 1 in the order of the inner liner X1 and the side rubber X2 so that a part of each overlaps in the drum diameter direction C. FIG. 2A shows a cross section at a position where the inner liner X1 and the side rubber X2 overlap in the drum diameter direction C in the drum axial direction A. By winding the strip-shaped rubber member X on the drum outer peripheral surface 2 of the tire molding drum 1 in this rubber member winding step, the strip-shaped rubber member X is formed into a cylindrical shape.

[0023] As shown in FIG. 2B, in the drum deformation step, the partial expansion / contraction segment 12 is retracted inward in the drum diameter direction C with respect to the adjacent segment 11, and a retracted surface 3 is formed on a part of the drum circumferential direction B of the drum outer peripheral surface 2. At this time, the belt-like rubber member X deforms inward in the drum diameter direction C along the retracted surface 3 at the position of the retracted surface 3 in the drum circumferential direction B. In the separator arrangement step, the separator 80 is arranged in the space formed by forming the retracted surface 3, that is, the space formed by the belt-like rubber member X deforming inward in the drum diameter direction C along the retracted surface 3.

[0024] As shown in FIG. 2C, in the ply winding step, the ply Y is wound along the drum outer peripheral surface 2 so as to cover the outside in the drum diameter direction C of the cylindrical belt-like rubber member X and the separator 80, and both end portions in the drum circumferential direction B of the ply Y are held on the separator 80. Further, as shown in FIG. 2C, in the joining step, each of the pair of joint rollers 71 of the joining device 70 is brought into contact with both end portions in the drum circumferential direction B of the ply Y, and each joint roller 71 is moved in the drum axis direction A while being rotated. Thereby, both end portions in the drum circumferential direction B of the ply Y are pulled closer to each other, and the end faces of these both end portions can be butted against each other for joining.

[0025] As shown in FIG. 2D, in the integration step, the separator 80 is pulled out in the drum axis direction A from between the belt-like rubber member X and the ply Y, and the partial expansion / contraction segment 12 is advanced outward in the drum diameter direction C to integrate the belt-like rubber member X and the ply Y. Thereby, the belt-like rubber member X can be pressed against the inner surface in the drum diameter direction C of the ply Y, and the belt-like rubber member X and the ply Y can be integrated.

[0026] Hereinafter, further details of the tire molding drum 1 of the present embodiment will be described.

[0027] Figures 3A and 3B are explanatory diagrams for explaining the mechanism that forms the retracted surface 3 of the tire molding drum 1 shown in FIG. 1. Specifically, FIG. 3A is a view showing the tire molding drum 1 before retracting the partial expansion / contraction segment 12 inward in the drum diameter direction C with respect to the adjacent segment 11. FIG. 3B is a view showing the tire molding drum 1 in a state where the partial expansion / contraction segment 12 is retracted inward in the drum diameter direction C with respect to the adjacent segment 11. In FIGS. 3A and 3B, among the plurality of segments 10 that form the drum outer peripheral surface 2, a total of three segments, namely one partial expansion / contraction segment 12 and a pair of adjacent segments 11 on both sides thereof, are shown. Hereinafter, for convenience of explanation, the state of the tire molding drum 1 shown in FIG. 3A may be described as the "state before partial diameter reduction", and the state of the tire molding drum 1 shown in FIG. 3B may be described as the "state after partial diameter reduction".

[0028] As shown in FIGS. 3A and 3B, the outer peripheral surfaces of each of the plurality of segments 10 together form one drum outer peripheral surface 2. Also, as shown in FIG. 3A, the plurality of segments 10 of the present embodiment form a drum outer peripheral surface 2 that is circular when viewed from the drum axis direction A in the state before partial diameter reduction. On the other hand, as shown in FIG. 3B, the plurality of segments 10 of the present embodiment form a drum outer peripheral surface 2 that is not circular when viewed from the drum axis direction A in the state after partial diameter reduction. Specifically, the drum outer peripheral surface 2 formed by the plurality of segments 10 of the present embodiment in the state after partial diameter reduction includes a retracted surface 3 formed by a part of the drum circumferential direction B retreating inward in the drum diameter direction C compared to the state before partial diameter reduction.

[0029] In this way, by forming the retreat surface 3 on the outer peripheral surface 2 of the drum, a space can be formed outside the retreat 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 this retreat surface 3. Therefore, it becomes difficult for the separator 80 to protrude outside the drum radial direction C from the outer peripheral surface 2 of the drum in the state before partial expansion and contraction. As a result, in the ply winding step (see FIG. 2C) described above, when the ply Y is wound so as to cover the outside of the separator 80 in the drum radial direction C, surplus of the ply Y is less likely to occur at the position where the separator 80 is arranged in the drum circumferential direction B, and it becomes easier to maintain the shape of the ply Y as a perfect circle when viewed from the drum axial direction A.

[0030] Also, as described above, the partial expansion and contraction segment 12 includes the moving body 20 and the swing flap 30. The outer surfaces of the moving body 20 and the swing flap 30 of the partial expansion and contraction segment 12 on the outside in the drum radial direction C are continuous in the drum circumferential direction B and constitute a part of the drum circumferential direction B of the drum outer peripheral surface 2 of the tire molding drum 1.

[0031] The swing 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 swing flap 30 of the present embodiment includes a connecting portion 36 attached to the 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 at a distance inside the drum radial direction C with respect to 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 around the shaft portion 40 while sliding on the shaft portion 40 and the pressing portion 41 between the shaft portion 40 and the pressing portion 41. In this way, the swing flap 30 of the present embodiment can swing with respect 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.

[0032] More specifically, the shaft portion 40 of the present embodiment includes an outer surface 40a located on the outer side in the drum radial direction C and an inner surface 40b located on the inner side in the drum radial direction C. The outer surface 40a of the shaft portion 40 constitutes a part of the outer peripheral surface 2 of the drum. The inner surface 40b of the shaft portion 40 is disposed to face the pressing portion 41. Further, 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 outer side 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] Also, the inner surface 36b of the connecting portion 36 located on the inner side in the drum radial direction C includes a convex curved surface substantially parallel to the outer surface 36a. The outer surface 41a of the pressing portion 41 located on the outer side 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 by sliding when the connecting portion 36 rotates around the shaft portion 40, the rotation of the connecting portion 36 around the shaft portion 40 is guided.

[0034] With such a configuration, while allowing the connecting portion 36 to rotate around the shaft portion 40, the movement of the connecting portion 36 in the drum radial direction C and the drum circumferential direction B can be restricted. In this way, the swing flap 30 of the present embodiment is pivotally supported by the adjacent segment 11 so as to be swingable in the drum radial direction C.

[0035] As shown in FIGS. 3A and 3B, the swing flap 30 swings in the drum radial direction C in conjunction with the movement of the moving body 20 in the drum radial direction C. For example, when the moving body 20 moves inward in the drum radial direction C from the state before partial diameter reduction (see FIG. 3A), the swing flap 30 swings inward in the drum radial direction C in conjunction therewith (see FIG. 3B). As a result, the partial expansion / contraction segment 12 retreats inward in the drum radial direction C with respect to the adjacent segment 11, and a retreat surface 3 is formed on a part of the drum circumferential direction B of the drum outer peripheral surface 2. In this way, when forming the retreat surface 3, by swinging the swing flap 30 in addition to the movement of the moving body 20, compared with the case where only the moving body 20 is moved to form the retreat surface 3, it is possible to suppress the occurrence of a sharp step in the drum radial direction C between the retreat surface 3 and the portion of the drum outer peripheral surface 2 other than the retreat surface 3. As a result, when the retreat surface 3 is formed in the above-described drum deformation process (see FIG. 2B), it becomes easier to hold the belt-like rubber member X wound in advance on the drum outer peripheral surface 2 along the retreat surface 3. As a result, in the subsequent separator arrangement process (see FIG. 2B), it is possible to suppress the state in which the belt-like rubber member X is separated outward in the drum radial direction C with respect to the retreat surface 3 and the arrangement of the separator 80 is inhibited by the belt-like rubber member X.

[0036] Note that when the moving body 20 moves outward in the drum radial direction C from the state after partial diameter reduction (see FIG. 3B), the swing flap 30 swings outward in the drum radial direction C in conjunction therewith (see FIG. 3A). As a result, the partial expansion / contraction segment 12 advances outward in the drum radial direction C with respect to the adjacent segment 11, and the drum outer peripheral surface 2 returns to the perfect circular state before the retreat surface 3 is formed.

[0037] As shown in FIGS. 3A and 3B, the partial expansion and contraction segment 12 of the present embodiment includes a pair of swing flaps 30 on both sides in the drum circumferential direction B of the moving body 20. However, the partial expansion and contraction segment 12 may include only one swing flap 30 on one side in the drum circumferential direction B of the moving body 20. However, by providing a pair of swing flaps 30 on both sides in the drum circumferential direction B of the moving body 20 as in the partial expansion and contraction segment 12 of the present embodiment, the belt-like rubber member X can be held in a state of being more along the retreat surface 3 as compared with the case where only one swing flap 30 is provided.

[0038] FIG. 4A is an enlarged view of part E in FIG. 3A, and is a view showing an enlarged part pivotally supported by the adjacent segment 11 of the swing flap 30 in the state before partial diameter reduction. FIG. 4B is an enlarged view of part F in FIG. 3B, and is a view showing an enlarged part pivotally supported by the adjacent segment 11 of the swing flap 30 in the state after partial diameter reduction. As described above, the swing flap 30 is swingable with respect 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 molding drum 1 varies from the state before partial diameter reduction to the state after partial diameter reduction, the end portion 37 in the drum circumferential direction B of the connecting portion 36 of the swing flap 30 moves to the outside in the drum radial direction C. The swing flap 30 of the present embodiment is configured such that the end portion 37 of the connecting portion 36 is located inside in the drum radial direction C with respect to the outer contour line S defined by the drum outer peripheral surface 2 of the tire molding drum 1 in the state before partial diameter reduction in the state after partial diameter reduction. By doing so, when the state after partial diameter reduction is achieved in the above-described drum deformation process, it is possible to suppress the belt-like rubber member X wound on the drum outer peripheral surface 2 from being damaged by the protruding end portion 37 to the outside in the drum radial direction C.

[0039] Next, a mechanism in which the swing flap 30 swings in the drum radial direction C in conjunction with the movement of the moving body 20 in the drum radial direction C will be described. As shown in FIGS. 3A and 3B, the moving body 20 of the present embodiment includes a cam groove 25 extending along the drum circumferential direction B. Further, the swing flap 30 of the present embodiment is housed in the cam groove 25 and includes a cam projection 35 that is movable in the extending direction of the cam groove 25 as the moving body 20 moves in the drum radial direction C. The moving body 20 and the swing flap 30 are connected to each other via the cam groove 25 and the cam projection 35. Note that the phrase "extends along the drum circumferential direction B" for the cam groove 25 does not mean that the cam groove 25 extends parallel to the drum circumferential direction B, but also includes the meaning of extending in a direction inclined within a range of a predetermined angle or less with respect to the drum circumferential direction B, that is, extending substantially parallel to the drum circumferential direction B.

[0040] Here, when the moving body 20 is moved inward in the drum diameter direction C from the state before partial diameter reduction (see FIG. 3A), the cam groove 25 also moves inward in the drum diameter direction C. As a result, a driving force directed inward in the drum diameter direction C is transmitted to the cam projection 35 accommodated in the cam groove 25 via the side wall of the cam groove 25. As a result, the cam projection 35 swings inward in the drum diameter direction C while moving relative to the cam groove 25 in the extending direction of the cam groove 25. Along with the movement of the cam projection 35, the swing flap 30 swings inward in the drum diameter direction C. Conversely, when the moving body 20 is moved outward in the drum diameter direction C from the state after partial diameter reduction, the cam groove 25 also moves outward in the drum diameter direction C. As a result, a driving force directed outward in the drum diameter direction C is transmitted to the cam projection 35 accommodated in the cam groove 25 via the side wall of the cam groove 25. As a result, the cam projection 35 moves outward in the drum diameter direction C while moving relative to the cam groove 25 in the extending direction of the cam groove 25. Along with the movement of the cam projection 35, the swing flap 30 swings outward in the drum diameter direction C. That is, by transmitting the driving force of the moving body 20 in the drum diameter direction C to the swing flap 30 via the cam groove 25 and the cam projection 35, the swing flap 30 of the present embodiment can swing in the drum diameter direction C in conjunction with the movement of the moving body 20 in the drum diameter direction C. Thus, by using the cam groove 25 and the cam projection 35, the swing flap 30 can be easily swung in conjunction with the movement of the moving body 20 in the drum diameter 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 moving body 20 shown in FIG. 1. FIG. 6B is a perspective view of the moving body 20 shown in FIG. 1 as viewed from a perspective different from that of FIG. 6A. As shown in FIGS. 5, 6A, and 6B, the cam groove 25 of the present embodiment is constituted by a recess that is recessed in the drum axial direction A. Further, as shown in FIG. 5, the cam projection 35 of the present embodiment is constituted by a projection that projects in the drum axial direction A. However, the cam groove 25 and the cam projection 35 are not limited to this as long as they swing the swing flap 30 in the drum radial direction C in conjunction with the movement of the moving body 20 in the drum radial direction C. For example, the cam groove 25 may be a recess that is recessed in the drum radial direction C, and the cam projection 35 may be a projection that projects in the drum radial direction C.

[0042] As shown in FIGS. 3A and 3B, the tire molding drum 1 of the present embodiment includes a moving body drive unit 50 that can drive the moving body 20 to the inside in the drum radial direction C so that the retracted surface 3 is formed. Further, the moving body drive unit 50 can drive the moving body 20 to the outside in the drum radial direction C after driving the moving body 20 to the inside in the drum radial direction C to form the retracted surface 3 and return to the state before the retracted surface 3 is formed. In other words, the moving body 20 of the present embodiment can move to the inside and the outside in the drum radial direction C by the moving body drive unit 50. The moving body drive unit 50 of the present embodiment is constituted by a cylinder mechanism, but the configuration of the moving body drive unit 50 is not particularly limited, and it may be constituted by, for example, a link mechanism, a slide mechanism, or the like.

[0043] Note that it is preferable that the moving body 20 moves 20 to 40 mm to the inside in the drum radial direction C from the state before partial diameter reduction (see FIG. 3A) so that the retracted surface 3 is formed. By doing so, it is possible to surely secure a space for arranging the separator 80 when the retracted surface 3 is formed.

[0044] As shown in Fig. 5, the moving body 20 of the present embodiment includes a first comb tooth portion 21 in which a plurality of convex portions 22 protruding in the drum circumferential direction B toward the swing flap 30 are arranged at intervals along the drum axial direction A. Further, the swing flap 30 of the present embodiment includes a second comb tooth portion 31 in which a plurality of convex portions 32 protruding in the drum circumferential direction B toward the moving body 20 are arranged at intervals along the drum axial direction A. Then, as shown in Fig. 5, the first comb tooth portion 21 and the second comb tooth portion 31 are engaged with each other.

[0045] Here, on the drum outer peripheral surface 2 of the tire molding drum 1, a gap 60 as a buffer space for the swing flap 30 to swing is formed at a position between the moving body 20 and the swing flap 30 in the drum circumferential direction B. This gap 60 is a non-pressing region where the belt-like rubber member X is not pressed against the drum outer peripheral surface 2 when the partial expansion segment 12 is advanced outward in the drum diameter direction C in the above-described integration process (see Fig. 2D) and the belt-like rubber member X is pressed against the inner surface of the ply Y in the drum diameter direction C. Therefore, when this non-pressing region becomes large, there is a possibility that air may stay between the belt-like rubber member X and the ply Y, that is, so-called air entrapment may occur. On the other hand, if the first comb tooth portion 21 and the second comb tooth portion 31 are configured to be engaged with each other as in the present embodiment, the gap 60 on the drum outer peripheral surface 2 can be dispersed at different positions in the drum circumferential direction B, and the maximum length Lm in which the gap 60 extends straight in the drum axial direction A can be reduced. Thereby, the occurrence of air entrapment in the non-pressing region (gap 60) can be suppressed.

[0046] FIG. 7A is a cross-sectional view showing a cross-section along the drum axial direction A of the tire molding drum 1 shown in FIG. 1. FIG. 7B is a cross-sectional view showing a state in which the diameter of the tire molding drum 1 is reduced without forming the retreat surface 3 from the state shown in FIG. 7A. As shown in FIGS. 7A and 7B, the tire molding drum 1 of the present embodiment includes a segment group drive unit 55 that can expand and contract a plurality of segments 10 as a whole in the drum diameter direction C separately from the moving body drive unit 50. By including this segment group drive unit 55, the tire molding drum 1 of the present embodiment can expand and contract the entire area of the drum circumferential direction B of the drum outer peripheral surface 2 while maintaining the drum outer peripheral surface 2 in a perfect circular shape. Note that the number of the plurality of segments 10 included in the tire molding drum 1 is preferably 8 to 16. By doing so, it becomes easier to maintain the roundness of the drum outer peripheral surface 2 when expanding and contracting the plurality of segments 10 as a whole in the drum diameter direction C.

[0047] The segment group drive unit 55 of the present embodiment is configured by a cylinder mechanism, but the configuration of the segment group drive unit 55 is not particularly limited, and it may be configured by, for example, a link mechanism, a slide mechanism, or the like. Further, in the present embodiment, the segment group drive unit 55 and the moving body drive unit 50 coexist by being arranged at different positions in the drum axial direction A, but the configuration for coexisting the segment group drive unit 55 and the moving body drive unit 50 is not limited to this.

[0048] The tire molding 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 Sustainable Development Goals (SDGs) Led by the United Nations] The SDGs have been proposed towards the realization of a sustainable society. One embodiment of the present invention can be a technology that contributes to "[No. 12_The Responsibility to Create, the Responsibility to Use]" and "[No. 13_Specific Measures for Climate Change]".

Industrial Applicability

[0050] The present disclosure relates to a tire building drum.

Explanation of Signs

[0051] 1: Tire building drum, 2: Drum outer peripheral surface, 3: Retreating surface, 5: Outer surface in the drum radial direction of a plurality of segments, 10: Segment, 11: Adjacent segment, 12: Partially expandable and contractible segment, 20: Moving body, 21: First comb tooth portion, 22: Convex portion, 25: Cam groove, 30: Swing flap, 31: Second comb tooth portion, 32: Convex portion, 35: Cam convex portion, 36: Connecting portion, 36a: Outer surface of the connecting portion, 36b: Inner surface of the connecting portion, 37: End portion of the connecting portion, 40: Shaft portion, 40a: Outer surface of the shaft portion, 40b: Inner surface of the shaft portion, 41: Pressing portion, 41a: Outer surface of the pressing portion, 45: Hinge mechanism, 50: Moving body drive portion, 55: Segment group drive portion, 60: Gap between the moving body and the swing flap in the drum circumferential direction formed on the drum outer peripheral surface, 70: Joining device, 71: Joint roller, 80: Separator, A: Drum axial direction, B: Drum circumferential direction, C: Drum radial direction, Lm: Maximum length in which the gap on the drum outer peripheral surface extends straight in the drum axial direction, O: Central axis, S: Outer contour line defined by the drum outer peripheral surface of the tire building drum in the state before partial diameter reduction, X: Belt-like rubber member, X1: Inner liner, X2: Side rubber, Y: Ply

Claims

1. It includes a plurality of segments arranged in the circumferential direction of the drum, and the outer surface in the drum radial direction forms a drum outer peripheral surface capable of supporting a tire material. The plurality of segments include partial expansion and contraction segments capable of forming a retracted surface on a part of the drum outer peripheral surface in the drum circumferential direction by retracting inward in the drum radial direction with respect to adjacent segments adjacent in the drum circumferential direction. The partial expansion and contraction segment includes a moving body movable in the drum radial direction, and a swing flap pivotally supported by the adjacent segment so as to be arranged across the moving body and the adjacent segment in the drum circumferential direction and swing in the drum radial direction in conjunction with the movement of the moving body in the drum radial direction. A tire molding drum.

2. The moving body includes a first comb tooth portion in which a plurality of convex portions protruding in the drum circumferential direction toward the swing flap are arranged at intervals along the drum axial direction. The swing flap includes a second comb tooth portion in which a plurality of convex portions protruding in the drum circumferential direction toward the moving body are arranged at intervals along the drum axial direction. The tire molding drum according to claim 1, wherein the first comb tooth portion and the second comb tooth portion are engaged with each other.

3. The moving body includes a cam groove extending along the drum circumferential direction. The swing flap includes a cam convex portion accommodated in the cam groove and movable in the extending direction of the cam groove as the moving body moves in the drum radial direction. The tire molding drum according to claim 1 or 2.

4. The tire molding drum according to claim 1 or 2, further comprising a moving body driving portion capable of driving the moving body inward in the drum radial direction so that the retracted surface is formed.

5. The tire molding drum according to claim 4, further comprising a segment group driving portion capable of expanding and contracting the plurality of segments in the drum radial direction, separate from the moving body driving portion.

6. The tire building drum according to claim 1 or 2, wherein the moving body is movable 20 to 40 mm inward in the drum diameter direction so that the rearward surface is formed.

7. The tire building drum according to claim 1 or 2, wherein the number of the plurality of segments is 8 to 16.

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