Molding drum

Abstract

To provide a molding drum capable of avoiding dislocation of a tip of a sheet-like rubber member without large-sizing.SOLUTION: A molding drum 10 to be wound with a sheet-like rubber member for a tire on its outer peripheral surface, is characterized by that: a plurality of segments are arranged in a drum circumferential direction with outer faces of respective segments coinciding with each other to form the outer peripheral surface of the molding drum 10; at least one of the plurality of segments is a tip-holding segment 20; the tip-holding segment 20 includes, as small segments arrayed in the drum circumferential direction, at least a first small segment 21 and a second small segment 22; and the first small segment 21 is capable of taking a first state where the second small segment 22 and the outer face coincide with each other and a second state where at least a part of the first small segment 21 is arranged at an outer side than the second small segment 22 in a drum diameter direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a molding drum.

Background Art

[0002] In the manufacturing process of pneumatic tires, there is a process in which a sheet-like rubber member is wound around a molding drum and formed into a cylindrical shape. When the sheet-like rubber member starts to be wound around the molding drum, the tip of the sheet-like rubber member is attached to the surface of the molding drum. The tip of the sheet-like rubber member only contacts the surface of the molding drum and adheres to the surface of the molding drum with a certain degree of strength.

[0003] However, the tip of the sheet-like rubber member may shift on the surface of the molding drum. Although the adhesiveness of the sheet-like rubber member varies slightly depending on the lot or the like, when the adhesiveness is small, it is particularly likely to shift on the surface of the molding drum. And if the tip of the sheet-like rubber member remains shifted, the completed tire will become a defective product.

[0004] Therefore, as described in Patent Document 1, it has been proposed to provide a drum clamp outside the drum diameter direction from the outer peripheral surface of the drum. According to this proposal, the tip of the member attached to the outer peripheral surface of the drum can be sandwiched between the outer peripheral surface of the drum and the drum clamp.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, with the above-mentioned drum clamp, the structure related to the drum clamp may be complicated, and the entire apparatus including the molding drum may be enlarged.

[0007] Therefore, the object of the present invention is to provide a molding drum that can prevent slippage of the tip of a sheet-like rubber member without increasing its size. [Means for solving the problem]

[0008] The present invention includes embodiments shown below.

[0009] [1] A molding drum in which a sheet-like rubber member for tires is wrapped around its outer circumference, wherein a plurality of segments are arranged in the circumferential direction of the drum, and the outer surfaces of each of the segments coincide to form the outer circumference of the molding drum, and at least one of the plurality of segments is a tip-holding segment, and the tip-holding segment comprises at least a first small segment and a second small segment as small segments arranged in the circumferential direction of the drum, and the first small segment can take a first state in which its outer surface coincides with that of the second small segment, and a second state in which at least a part of the first small segment is positioned radially outward from the second small segment.

[0010] [2] The molding drum according to [1], wherein the tip-holding segment is divided into the first sub-segment and the second sub-segment over the entire length of the drum axis.

[0011] [3] The molding drum according to [1] or [2], wherein the portion of the first subsegment that faces the outer surface of the second subsegment when in the second state is formed as a flexible portion.

[0012] [4] A molding drum according to any one of [1] to [3], wherein a moving device for moving the first small segment from the first state to the second state is arranged radially inward from the first small segment.

[0013] [5] A molding drum according to any one of [1] to [4], wherein a moving device for moving the first small segment from the first state to the second state is provided, the first moving device for moving the first small segment in the radial direction of the drum, and the second moving device for moving the first small segment, which has moved outward in the radial direction of the drum, toward the second small segment. [Effects of the Invention]

[0014] Despite not being significantly enlarged, the molding drum described above can prevent the leading edge of the sheet-like rubber component from shifting. [Brief explanation of the drawing]

[0015] [Figure 1] A perspective view of the molding drum during the expansion process. [Figure 2] A view of the molding drum during the expansion process, seen from the direction of the drum axis (viewed from the direction of arrow A in Figure 1). [Figure 3] A view of the molding drum in the axial direction when it is reduced in diameter. [Figure 4] A view of the tip holding device from the drum axis direction. This diagram shows the first small segment in the retracted position. [Figure 5] This diagram shows the moving device viewed from the outside in the radial direction of the drum (viewed from the direction of arrow B in Figure 1). The vertical direction is the drum axis direction. [Figure 6] This diagram shows the tip holding device viewed from the circumferential direction of the drum (viewed from the direction corresponding to arrow C in Figure 1). The left-right direction is the drum axis direction. [Figure 7] This diagram shows the second and third sub-segments viewed from the outside in the radial direction of the drum. The left-right direction is the drum axis direction. [Figure 8] A view of the second and third sub-segments from the drum axis direction. The vertical direction is the drum radial direction. [Figure 9] A view of the tip holding device from the drum axis direction. This diagram shows the first small segment when it has advanced radially outward from the drum. [Figure 10]View of the tip holding device as seen from the drum axis direction. View when the first small segment moves toward the second small segment. [Figure 11] View of the tip holding device as seen from the drum axis direction. View when a sheet-like rubber member is sandwiched between the first small segment and the second small segment. [Figure 12] Block diagram of the control unit etc. [Figure 13] Flow diagram of the molding of the cylindrical rubber member. [Figure 14] Diagram for explaining the method of winding the sheet-like rubber member around the molding drum. Diagram showing the state when the sheet-like rubber member is attached to the second small segment. [Figure 15] Diagram for explaining the method of winding the sheet-like rubber member around the molding drum. Diagram showing the state when the tip holding device holds the sheet-like rubber member. [Figure 16] Diagram for explaining the method of winding the sheet-like rubber member around the molding drum. Diagram showing the state when the molding drum rotates nearly one turn and stops. [Figure 17] Diagram for explaining the method of winding the sheet-like rubber member around the molding drum. Diagram showing the state when the first small segment returns to the retracted state. [Figure 18] Diagram for explaining the method of winding the sheet-like rubber member around the molding drum. Diagram showing the state when the molding drum rotates again and the sheet-like rubber member is attached to the first small segment. [Figure 19] View of the tip holding device of the modification as seen from the drum axis direction. [Figure 20] Diagram showing the state in the modification when the first small segment does not hit the sheet-like rubber member even when it is in the tilted state.

Mode for Carrying Out the Invention

[0016] The embodiments will be described based on the drawings. Note that the embodiments described below are merely examples, and those appropriately modified without departing from the gist of the present invention are included in the scope of the present invention.

[0017] The molding drum 10 shown in Figures 1 and 2 is a drum for molding a cylindrical rubber member by winding a sheet-like rubber member around its outer surface. The sheet-like rubber member is a component of a pneumatic tire. The sheet-like rubber member is made of rubber, but may contain non-rubber materials such as metal or organic fiber cords inside. The cylindrical rubber member molded from the sheet-like rubber member becomes part of a pneumatic tire.

[0018] As shown in Figures 1 and 2, the molding drum 10 is provided with a plurality of segments 11 arranged in the circumferential direction of the drum. Each segment 11 is a long member in the direction of the drum axis. The outer surface of each segment 11 in the radial direction of the drum (hereinafter referred to as the "outer surface") is a curved surface. Each outer surface 11a is part of the outer circumferential surface of the molding drum 10. The outer circumferential surface of the molding drum 10 is a single cylindrical surface that forms the outer circumference of the molding drum 10 and becomes the molding surface during molding.

[0019] When viewed from the outside in the radial direction of the drum, both ends of each segment 11 in the circumferential direction of the drum have a concave-convex shape portion 11b in which concave and convex shapes are arranged alternately in the direction of the tire axis. The concave-convex shape portions 11b of adjacent segments 11 are configured to interlock with each other.

[0020] Furthermore, each segment 11 is made of a metal such as stainless steel. The outer surface 11a of each segment 11 is a smooth metal surface.

[0021] Each segment 11 is attached to the outer portion of the segment holding member 12 in the radial direction of the drum. The segment holding member 12 is positioned inward from the segments 11 in the radial direction of the drum.

[0022] A known segment drive device 53 (see Figure 12), consisting of a cylinder or the like, is provided inside the molding drum 10. When the segment drive device 53 is driven, each segment 11 moves in the radial direction of the drum.

[0023] As the segments 11 move outward in the radial direction of the drum, the molding drum 10 expands in diameter. Diameter expansion means that the diameter increases. Figures 1 and 2 show the molding drum 10 when it has expanded in diameter. As shown in Figures 1 and 2, as the molding drum 10 expands in diameter, adjacent segments 11 come into contact with each other, and the outer surfaces 11a of all segments 11 become one cylindrical surface. In this state, a sheet-like rubber member is wrapped around it, and a cylindrical rubber member is molded.

[0024] Figure 3 shows the molding drum 10 when its diameter is reduced. Diameter reduction refers to a decrease in diameter. As the segments 11 move inward in the radial direction of the drum, the molding drum 10 is reduced in diameter as shown in Figure 3. When the molding drum 10 is reduced in diameter, segments 11 that have moved significantly inward in the radial direction of the drum and segments 11 that have moved slightly inward in the radial direction of the drum are arranged alternately in the circumferential direction of the drum. When the molding drum 10 is reduced in diameter after the cylindrical rubber member has been molded on the molding surface, a gap is created between the cylindrical rubber member and the outer surface 11a of the segments 11, making the cylindrical rubber member removable.

[0025] One of these segments 11 is replaced by a tip-holding segment 20. The tip-holding segment 20 is part of a tip-holding device 13 for holding the tip of the sheet-like rubber member. The tip of the sheet-like rubber member refers to the part where the sheet-like rubber member begins to be wound up.

[0026] The tip-holding segment 20 consists of three sub-segments 21, 22, and 23. The three sub-segments 21, 22, and 23 are arranged in the circumferential direction of the drum. The three sub-segments 21, 22, and 23 consist of a first sub-segment 21 in the center of the circumferential direction of the drum, a second sub-segment 22 on one side of the circumferential direction of the drum, and a third sub-segment 23 on the other side of the circumferential direction of the drum.

[0027] The second and third sub-segments 22 and 23 have the same length in the tire axis direction as the other segments 11. On the other hand, the first sub-segment 21 is longer in the drum axis direction than the other segments 11. As shown in Figure 5, the portions of the first sub-segment 21 on both sides in the drum axis direction protrude outward in the drum axis direction than the other segments 11, and these portions are held by the first moving device 30, which will be described later.

[0028] Each of the sub-segments 21, 22, and 23 is made of a metal such as stainless steel. The outer surfaces 21a, 22a, and 23a of each of the sub-segments 21, 22, and 23 (see Figure 4, etc.) are smooth metal surfaces. The surface roughness of the outer surfaces 21a, 22a, and 23a of sub-segments 21, 22, and 23a, such as the arithmetic mean roughness Ra, is the same as that of the outer surface 11a of the other segment 11.

[0029] On the inner surface of the first sub-segment 21 in the drum radial direction (hereinafter referred to as the "back surface"), the portion on the side of the second sub-segment 22 is formed as a flexible portion 27. The flexible portion 27 is located on the side of the second sub-segment 22 of the first sub-segment 21, relative to the center in the drum circumferential direction. The flexible portion 27 also includes the end of the first sub-segment 21 on the side of the second sub-segment 22. Preferably, the length of the flexible portion 27 in the drum axial direction matches the length of the adjacent second sub-segment 22 in the drum axial direction.

[0030] The flexible portion 27 is the part that bends and deforms when the tip of the sheet-like rubber member is held by the first small segment 21 and the second small segment 22, as will be described later. This deformation is reversible. The flexible portion 27 is made of one of the following materials: rubber, epoxy resin, foamed resin, sponge, etc. A member made of such a material is fitted into a notch formed on the back surface of the first small segment 21 to form the flexible portion 27.

[0031] As shown in Figures 7 and 8, the second sub-segment 22 and the third sub-segment 23 are connected by a connecting portion 25 located radially inward from the first sub-segment 21. The second sub-segment 22, the third sub-segment 23, and the connecting portion 25 form a recess 26 into which the first sub-segment 21 fits. When the first sub-segment 21 fits into the recess 26, the outer surfaces 21a, 22a, and 23a of the three sub-segments 21, 22, and 23 form a single curved surface, as shown in Figure 4.

[0032] The second sub-segment 22 and the third sub-segment 23 are provided to be movable in the drum radial direction together with the other segments 11. The segment drive device 53 that moves the second sub-segment 22 and the third sub-segment 23 in the drum radial direction is the same as the segment drive device 53 that moves the other segments 11 in the drum radial direction. When the second sub-segment 22 and the third sub-segment 23 move in the drum radial direction together with the other segments 11, the first sub-segment 21 also moves in the drum radial direction together with the second sub-segment 22, etc.

[0033] The first small segment 21, located in the circumferential center of the drum, is movable relative to the second small segment 22 and the third small segment 23. Moving devices for moving the first small segment 21 are provided on both sides of the drum axis.

[0034] As moving devices, a first moving device 30 and a second moving device 40 are provided, as shown in Figures 1 to 4. The first moving device 30 is a device that moves the first small segment 21 in the radial direction of the drum. The second moving device 40 is a device that moves the first small segment 21, which has moved outward in the radial direction of the drum, toward the second small segment 22. The first moving device 30 and the second moving device 40 together with the tip holding segment 20 constitute the tip holding device 13.

[0035] As shown in Figures 1 to 4, the first moving device 30 and the second moving device 40 are attached to the same single plate 24. The plate 24 is L-shaped when viewed from the direction of the drum axis. The first moving device 30 is attached to the first portion 24a (see Figure 4), which corresponds to one side of the L-shape of the plate 24 and extends in the direction of the drum diameter. The second moving device 40 is attached to the second portion 24b (see Figure 4), which corresponds to the other side of the L-shape of the plate 24.

[0036] As shown in Figures 5 and 6, the first portion 24a of the plate 24 is attached to the segment holding member 14 that holds the tip-holding segment 20 via bolts 15. The bolts 15 extend perpendicular to the plate 24. The plate 24 is attached to the drum axial end of the segment holding member 14. The plate 24 can move in the drum radial direction together with the segment holding member 14.

[0037] As shown in Figure 4, the plate 24, the first moving device 30, and the second moving device 40 are located radially inward from the first small segment 21 in the drum direction. Furthermore, the plate 24, the first moving device 30, and the second moving device 40 are located radially inward from the outer surfaces 21a, 22a, and 23a of the tip-holding segment 20 when the first small segment 21 is fitted into the recess 26 (in the retracted state described later).

[0038] Furthermore, the plate 24 is mounted on the drum axis side of the segment holding member 14. The first moving device 30 and the second moving device 40 are attached to the drum axis side surface of the plate 24.

[0039] As shown in Figure 4, the first moving device 30 comprises a cylinder 31, a rod 32 that moves back and forth relative to the cylinder 31, a guide 33 that moves back and forth next to the rod 32 and together with the rod 32, and a fixing device 35 to which the ends of the rod 32 and the guide 33 are fixed. In addition, a first connecting member 36 is fixed to the inner surface of the fixing device 35 in the direction of the drum axis as part of the first moving device 30.

[0040] The rod 32 moves forward and backward by the intake and exhaust of a fluid such as air into the cylinder 31. The rod 32 and the guide 33 extend in the radial direction of the drum.

[0041] As shown in Figure 6, the fastener 35 consists of a first portion 35a, which is a plate-shaped portion to which the ends of the rod 32 and the guide 33 are fixed, and a second portion 35b, which is a plate-shaped portion extending from the inner end of the first portion 35a in the drum axis direction in the same direction as the extension direction of the rod 32. The longitudinal directions of the rod 32 and the guide 33 are perpendicular to the plate-shaped first portion 35a.

[0042] The fastener 35 is located outward in the drum axis direction from the plate 24. The second portion 35b of the fastener 35 is parallel to the plate 24. The second portion 35b of the fastener 35 and the plate 24 are facing each other with a slight gap between them.

[0043] As shown in Figures 5 and 6, a shaft 37 protrudes from the second portion 35b of the fixture 35 toward the center in the drum axis direction, as part of the first moving device 30. This shaft 37 is inserted into a hole formed in the plate 24 that extends in the direction of the drum axis. Around this shaft 37, the fixture 35 and the first moving device 30 fixed thereto can change angle on the outer surface of the plate 24 in the drum axis direction. The way the angle of the first moving device 30 changes around the shaft 37 is shown in Figures 9 and 10.

[0044] As shown in Figures 4 and 6, the first small segment 21 is fixed to the cylinder 31 on the side opposite to the rod 32 and guide 33. More specifically, the area near the drum axial end of the first small segment 21 is fixed to the cylinder 31 by a bolt 28 acting as a fastener. The first small segment 21 is perpendicular to the longitudinal direction of the rod 32 and guide 33. As the rod 32 of the first moving device 30 moves forward and backward, the first small segment 21 fixed to the cylinder 31 advances outward in the drum radial direction or retracts inward in the drum radial direction.

[0045] As shown in Figure 9, the state in which the first sub-segment 21 extends radially outward from the second sub-segment 22 and the third sub-segment 23 in the drum direction is defined as the advanced state of the first sub-segment 21. Also, as shown in Figure 4, the state in which the outer surface 21a of the first sub-segment 21 coincides with the outer surfaces 22a and 23a of the second sub-segment 22 and the third sub-segment 23 is defined as the retracted state of the first sub-segment 21. In this embodiment, the retracted state is defined as the first state. In the description of segments and sub-segments, when the outer surfaces coincide, it means that their outer surfaces form a single curved surface together.

[0046] When the first sub-segment 21 is in the retracted position, as shown in Figure 2, the outer surfaces 21a, 22a, and 23a of the three sub-segments 21, 22, and 23 coincide with the outer surface 11a of the other multiple segments 11. The single curved surface formed at this time is cylindrical and is the outer surface of the molding drum 10. The formation of a single cylindrical outer surface makes it possible to mold a cylindrical rubber member on that outer surface.

[0047] As shown in Figures 4 and 5, the second moving device 40 comprises a cylinder 41, a rod 42 that moves back and forth relative to the cylinder 41, and a second connecting member 43 fixed to the tip of the rod 42. The rod 42 moves back and forth by drawing in and expelling a fluid such as air from the cylinder 41.

[0048] The cylinder 41 is attached to the plate 24 via a shaft member 44. The second moving device 40 can change its angle around the shaft member 44. Figures 9 and 10 show how the angle of the second moving device 40 changes around the shaft member 44.

[0049] As can be seen from Figure 4, when viewed from the direction of the drum axis, the rod 42 of the second moving device 40 is not parallel to the rod 32 of the first moving device 30, but at an angle. Furthermore, the tip of the rod 42 of the second moving device 40 is movable inward in the drum axis direction compared to the rod 32 of the first moving device 30.

[0050] The second connecting member 43, provided at the tip of the rod 42 of the second moving device 40, overlaps with the first connecting member 36 of the first moving device 30 in the direction of the drum axis. A shaft member 45, extending in the direction of the drum axis, passes through this overlapping portion. In this way, the first connecting member 36 and the second connecting member 43 are connected. This portion consisting of the first connecting member 36, the second connecting member 43, and the shaft member 45 is a knuckle joint. When the rod 42 of the second moving device 40 moves forward and backward, the knuckle joint moves in the direction of the rod 42's movement.

[0051] The rod 42 of the second moving device 40 moves forward and backward when the first small segment 21 is in the extended position. When the rod 42 of the second moving device 40 moves forward and backward, the orientation of the first moving device 30 changes, and the first small segment 21 moves.

[0052] In detail, firstly, in the first stage, the first small segment 21 is extended, and the rod 42 of the second moving device 40 is extended (i.e., the state shown in Figure 9). At this time, the first moving device 30 is oriented so that the longitudinal direction of its rod 32 is in the direction of the drum diameter.

[0053] Next, in the second stage, as shown in Figure 10, the rod 42 of the second moving device 40 retracts, shortening the distance from the cylinder 41 to the second connecting member 43. As a result, the first connecting member 36 of the first moving device 30 is pulled toward the cylinder 41 of the second moving device 40 by the rod 42 of the second moving device 40. As the first connecting member 36 is pulled, the entire first moving device 30 tilts by a predetermined angle around the axis 37. At this time, the inner portion of the first moving device 30 in the radial direction of the drum moves toward the cylinder 41 of the second moving device 40, and the outer portion in the radial direction of the drum moves toward the second small segment 22. Because the first moving device 30 tilts in this way, the first small segment 21, which is attached to the outer portion of the first moving device 30 in the radial direction of the drum, moves toward the second small segment 22.

[0054] After the second stage, when the rod 42 of the second moving device 40 extends again, the first connecting member 36 of the first moving device 30 is pushed by the rod 42 of the second moving device 40, causing the entire first moving device 30 to tilt by a predetermined angle around the axis 37. As the first moving device 30 tilts, the position of the first small segment 21 returns to the position shown in Figure 9.

[0055] As shown in Figure 9, when the first small segment 21 is extended and the rod 42 of the second moving device 40 is extended, the first small segment 21 is positioned radially outward from the connecting portion 25 between the second small segment 22 and the third small segment 23. At this time, the first small segment 21 is at the same height as both the second small segment 22 and the third small segment 23. This state is referred to as the upright state of the first small segment 21.

[0056] As shown in Figure 10, when the first small segment 21 is in the extended position and the rod 42 of the second moving device 40 is retracted, the first small segment 21 is tilted toward the second small segment 22 compared to when it is in the upright position. A part of the first small segment 21 is positioned radially outward of the second small segment 22. At this time, the flexible portion 27 on the back surface of the first small segment 21 faces the outer surface 22a of the second small segment 22. Here, "facing" means that a perpendicular line drawn to the outer surface 22a of the second small segment 22 intersects the flexible portion 27 of the first small segment 21.

[0057] Thus, the state in which the first sub-segment 21 in the extended state is tilted and the flexible portion 27 faces the outer surface 22a of the second sub-segment 22 is defined as the tilted state of the first sub-segment 21. In this embodiment, the tilted state is defined as the second state. When the first sub-segment 21 is in the tilted state, the distance between the flexible portion 27 of the first sub-segment 21 and the outer surface 22a of the second sub-segment 22 is, for example, 10 mm or more and 15 mm or less. Here, the distance refers to the length in the direction perpendicular to the outer surface 22a of the second sub-segment 22.

[0058] When the first sub-segment 21 is tilted, as shown in Figure 11, the tip of the sheet-like rubber member 1 can be sandwiched between the flexible portion 27 of the first sub-segment 21 and the outer surface 22a of the second sub-segment 22. When the tip of the sheet-like rubber member 1 is sandwiched, the flexible portion 27 of the first sub-segment 21 deforms. The elastic force resulting from the deformation of the flexible portion 27 firmly holds the tip of the sheet-like rubber member 1 between the flexible portion 27 and the outer surface 22a of the second sub-segment 22.

[0059] The first moving device 30, the second moving device 40, and the plate 24 to which they are attached are provided on both sides in the direction of the drum axis, as shown in Figure 6. The first moving device 30, the second moving device 40, and the plate 24 are arranged symmetrically with respect to a plane that passes through the axial center of the molding drum 10 and is perpendicular to the direction of the drum axis.

[0060] The operation of the molding drum 10 is controlled by the control unit 50. As shown in Figure 12, at least the first operating device 51, the second operating device 52, the segment drive device 53, the drum rotating device 54, and the material supply device 55 are connected to the control unit 50. The first operating device 51, the second operating device 52, the segment drive device 53, and the drum rotating device 54 are part of the molding drum 10.

[0061] The first operating device 51 is a device that changes the amount of fluid in the cylinder 31 in order to move the rod 32 of the first moving device 30 forward and backward. The first operating device 51 causes the first moving devices 30 on both sides in the drum axis direction to operate simultaneously. The second operating device 52 is a device that changes the amount of fluid in the cylinder 41 in order to move the rod 42 of the second moving device 40 forward and backward. The second operating device 52 causes the second moving devices 40 on both sides in the drum axis direction to operate simultaneously.

[0062] Furthermore, the drum rotating device 54 is a well-known device for rotating the molding drum 10, and includes, for example, a motor. The material supply device 55 is a device for supplying sheet-shaped rubber material to the molding drum 10.

[0063] Various types of tire-grade rubber materials can be used as sheet-like rubber components to be wrapped around the molding drum 10. Examples of sheet-like rubber components include single-piece sheet-like rubber components such as inner liners and belts. Other examples of sheet-like rubber components include sheet-like rubber components made by bonding multiple sheet-like components together, such as a temporary assembly in which a chafer and sidewall rubber are attached to both sides of an inner liner in the width direction. It is also possible to wrap one sheet-like rubber component on each side of the drum axis direction simultaneously. Examples of sheet-like rubber components wrapped simultaneously on both sides of the drum axis direction include chafers and sidewall rubber.

[0064] A sheet-like rubber member is wrapped around the outer surface of the molding drum 10 having the above configuration to form a cylindrical rubber member. The length of the sheet-like rubber member is approximately the same as the circumference of the molding drum 10. Molding in the molding drum 10 is performed under the control of the control unit 50. The molding process is as shown in Figure 13.

[0065] In detail, first, a material supply device 55 that supplies the sheet-like rubber member 1 to the molding drum 10 approaches the molding drum 10. Then, the leading edge of the sheet-like rubber member 1 supplied from the material supply device 55 is attached to the second small segment 22 of the molding drum 10 (S1 in Figure 13, Figure 14). The sheet-like rubber member 1 adheres to the outer surface 22a of the second small segment 22 due to its adhesive force. At this time, it is preferable that the leading edge of the sheet-like rubber member 1 coincides with or is close to the boundary between the first small segment 21 and the second small segment 22. Note that at this time, the first small segment 21 is in a retracted state.

[0066] Next, the first moving device 30 is activated, causing the first small segment 21 to extend (stand upright) (see Figure 9). Then, the second moving device 40 is activated, causing the first small segment 21 to tilt toward the second small segment 22, resulting in a tilted state (see Figure 10).

[0067] As the first small segment 21 tilts, the tip of the sheet-like rubber member 1 is sandwiched between the flexible portion 27 on the back surface of the first small segment 21 and the outer surface 22a of the second small segment 22. As a result, the tip holding device 13 holds the tip of the sheet-like rubber member 1 (S2 in Figure 13, Figure 15).

[0068] After the tip holding device 13 holds the tip of the sheet-like rubber member 1, the molding drum 10 starts to rotate (S3 in Figure 13). The tip holding device 13 continues to hold the tip of the sheet-like rubber member 1 while the molding drum 10 is rotating. As the molding drum 10 rotates, the sheet-like rubber member 1 is wound onto the molding drum 10.

[0069] When the molding drum 10 has rotated nearly one full turn and the tip of the sheet-like rubber member 1 has reached a predetermined position (YES in S4 of Figure 13), the rotation of the molding drum 10 stops (S5 in Figure 13, Figure 16). At this time, the sheet-like rubber member 1 is wrapped around almost the entire outer surface of the molding drum 10, but it is not attached to the outer surface 21a of the first small segment 21.

[0070] After the molding drum 10 stops rotating, the second moving device 40 is activated, causing the first small segment 21 to return to an upright position (see Figure 9). As a result, the first small segment 21 separates from the sheet-like rubber member 1, and the holding of the sheet-like rubber member 1 by the tip holding device 13 is released (S6 in Figure 13).

[0071] Next, the first moving device 30 is activated, causing the first small segment 21 to return to its retracted state (S7 in Figure 13, Figure 17). As a result, the outer surface 21a of the first small segment 21 coincides with the outer surface 22a of the second small segment 22 and the outer surface 23a of the third small segment 23.

[0072] After the first small segment 21 returns to its retracted position, the molding drum 10 rotates again. This rotation causes the sheet-like rubber member 1 to adhere to the outer surface 21a of the first small segment 21 (S8 in Figure 13, Figure 18).

[0073] When the sheet-like rubber member 1 is wound up completely (YES in S9 of Figure 13), the rear end of the sheet-like rubber member 1 coincides with or overlaps with the front end. The molding of the cylindrical rubber member is completed when the sheet-like rubber member 1 is wound up completely. The completed cylindrical rubber member is sent to a later process and used as part of a pneumatic tire.

[0074] Such a molding drum 10 can prevent the tip of the sheet-like rubber member from shifting despite not being enlarged. In detail, the molding drum 10 is equipped with a first small segment 21 and a second small segment 22 as small segments arranged in the circumferential direction of the drum. The first small segment 21 can take two states: a first state (retracted state) in which its outer surface coincides with that of the second small segment 22, and a second state (tilted state) in which a part of the first small segment 21 is located on the radially outer side of the second small segment 22. In this second state, the first small segment 21 and the second small segment 22 are configured to sandwich the tip of the sheet-like rubber member.

[0075] In this way, the tip of the sheet-like rubber member can be gripped, preventing the tip of the sheet-like rubber member from shifting. Here, the device that grips the tip of the sheet-like rubber member is not a device or the like provided radially outward from the outer surface of the molding drum 10, but rather the first small segment 21 and the second small segment 22 of the tip-holding segment 20, which is also one of the segments, so the molding drum 10 is not enlarged. In this way, the molding drum 10 can prevent the tip of the sheet-like rubber member from shifting despite not being enlarged.

[0076] Furthermore, since the tip-holding segment 20 is divided into a first sub-segment 21 and a second sub-segment 22 along the entire length in the direction of the drum axis, it can hold not only narrow sheet-like rubber members but also wide sheet-like rubber members. In addition, it can hold wide sheet-like rubber members made by bonding multiple sheet-like members together.

[0077] Furthermore, since the portion of the first sub-segment 21 that faces the outer surface 22a of the second sub-segment 22 when it is in the second state (tilted state) is formed as a flexible portion 27, the tip of the sheet-like rubber member can be firmly held by the flexible portion 27 and the outer surface 22a of the second sub-segment 22. Therefore, it is possible to prevent the tip of the sheet-like rubber member from slipping.

[0078] Furthermore, since the first moving device 30 and the second moving device 40, which move the first small segment 21, are positioned radially inward from the first small segment 21, the molding drum 10 does not become larger. Also, due to this arrangement, even if the first moving device 30 and the second moving device 40 rotate together with the segment 11, etc., problems such as them hitting surrounding objects of the molding drum 10 do not occur.

[0079] Furthermore, as a moving device for moving the first small segment 21, a first moving device 30 is provided to move the first small segment 21 in the drum radial direction, and a second moving device 40 is provided to tilt the first small segment 21, which has moved outward in the drum radial direction, toward the second small segment 22. Therefore, a two-stage operation can be achieved in which the first small segment 21 is moved in the drum radial direction to an upright state (extended state), and the upright first small segment 21 is tilted toward the second small segment 22 to a tilted state. Through this two-stage operation, the first small segment 21 can reliably press against the tip of the sheet-like rubber member on the outer surface 22a of the second small segment 22 from the outside in the drum radial direction.

[0080] Furthermore, since the first moving device 30 and the second moving device 40 are operated by a fluid such as air, it is easy to adjust the magnitude of the force that the first small segment 21 applies to hold down the sheet-like rubber member.

[0081] Furthermore, since the first moving device 30 and the second moving device 40 are provided on both sides of the first small segment 21 in the drum axis direction, the first small segment 21 can be operated simultaneously by the devices on both sides in the drum axis direction. As a result, even if the first small segment 21 is long in the drum axis direction, the entire first small segment 21 can be reliably moved.

[0082] Furthermore, because the outer surface 22a of the second small segment 22, to which the tip of the sheet-like rubber member is first attached, is a smooth metallic surface rather than a flexible surface, the tip of the sheet-like rubber member adheres easily to the outer surface 22a of the second small segment 22.

[0083] Various modifications can be made to the above embodiments. One of the modification examples described below may be applied to the above embodiments, or two or more may be applied to the above embodiments in combination. The combinations can be made freely as long as they do not result in technical inconsistencies.

[0084] <Example of change 1> The flexible portion does not need to be present in any part of the first or second sub-segment, including the back surface of the first sub-segment. Even without a flexible portion, the tip of the sheet-like rubber member can be held between the back surface of the first sub-segment and the outer surface of the second sub-segment.

[0085] <Example of change 2> The outer surface of the second sub-segment may be formed as a flexible portion in the part facing the tilted first sub-segment. In that case, the same flexible portion as in the above embodiment may be provided on the back surface of the first sub-segment, or the back surface of the first sub-segment may not have a flexible portion. Even when the outer surface of the second sub-segment is formed as a flexible portion, the tip of the sheet-like rubber member can be firmly held.

[0086] <Example of change 3> The flexible portion may be formed by applying a liquid made of resin or the like to a predetermined portion of the first small segment 21.

[0087] <Example of change 4> The portion of the sheet-like rubber member that contacts the sheet-like rubber member when holding its tip is not limited to the back surface of the first small segment and the outer surface of the second small segment.

[0088] A second state is achieved in which at least a portion of the first sub-segment moves to a position radially outward of the second sub-segment in the drum direction, and it is sufficient if, in the second state, the tip of the sheet-like rubber member can be sandwiched between any portion of the first sub-segment and any portion of the second sub-segment.

[0089] <Example of change 5> The first and second moving devices for moving the first sub-segment are not limited to those utilizing cylinders as in the above embodiment. The first and second moving devices can be any device capable of moving the first sub-segment. For example, the first and second moving devices may utilize motors.

[0090] <Example of change 6> The first and second moving devices for moving the first sub-segment may be provided on only one side in the drum axis direction. It is sufficient if the first sub-segment can be moved using only the first and second moving devices on one side in the drum axis direction.

[0091] <Example of change 7> The moving device for the first sub-segment does not need to be divided into a first moving device and a second moving device as in the above embodiment; it may be a single device. It is sufficient that the operation of a single moving device can cause the first sub-segment to take on two states: a first state in which its outer surface coincides with that of the second sub-segment, and a second state in which at least a portion of the first sub-segment is located outside the second sub-segment in the drum radial direction.

[0092] <Example of change 8> The relative positions of the cylinder 31 and the rod 32 of the first moving device 30 may be reversed from those in the above embodiment. Specifically, as shown in Figure 19, the rod 32 of the first moving device 30 may be located outward in the drum axial direction from the cylinder 31, and the first small segment 21 may be fixed to the tip of the rod 32. In this case, the first small segment 21 may be fixed to the rod 32 with another member in between.

[0093] <Example of change 9> The molding process for the cylindrical rubber member may differ from that of the above embodiment. For example, after the tip of the sheet-like rubber member 1 is attached to the second small segment 22 of the molding drum 10, the molding drum 10 may rotate by a small angle (this rotation is called a "small rotation") to slightly wind up the sheet-like rubber member 1. In this case, the rotation of the molding drum 10 stops after the small rotation, and the tip holding device 13 holds the tip of the sheet-like rubber member 1 during this stop. After that, the molding drum 10 resumes rotation and winds up the remaining portion of the sheet-like rubber member 1.

[0094] <Example of change 10> The operation of sandwiching the tip of the sheet-like rubber member between the first small segment 21 and the second small segment 22 is not limited to the operation of the above embodiment.

[0095] In this modified example, first, the tip of the sheet-like rubber member is attached to the outer surface 22a of the second small segment 22. Next, when the first moving device 30 is operated, the first small segment 21 moves into an extended state (upright state) (see Figure 9). Next, when the second moving device 40 is operated, the first small segment 21 tilts toward the second small segment 22 and moves into a tilted state. The two-stage operation of the first small segment 21 up to this point is the same as when the tip of the sheet-like rubber member is sandwiched between the first small segment 21 and the second small segment 22 in the above embodiment. However, as shown in Figure 20, in this modified example, when the first small segment 21 is in the tilted state, the first small segment 21 does not come into contact with the sheet-like rubber member.

[0096] In this modified example, after the first small segment 21 is tilted, the third stage of operation involves the first moving device 30 operating, causing the first small segment 21 to retract slightly inward in the drum radial direction. As the first small segment 21 retracts slightly, the tip of the sheet-like rubber member is caught between the first small segment 21 and the second small segment 22 (see Figure 11).

[0097] In this modified example as well, the tip of the sheet-like rubber member is firmly held between the first sub-segment 21 and the second sub-segment 22.

[0098] <Example of change 11> A single molding drum 10 may be provided with multiple tip-holding segments 20. In this case, the multiple tip-holding segments 20 may be arranged at equal intervals in the circumferential direction of the drum. [Explanation of symbols]

[0099] 1...Sheet-shaped rubber member, 10...Molding drum, 11...Segment, 11a...Outer surface, 11b...Uneven shape portion, 12...Segment holding member, 13...Tip holding device, 14...Segment holding member, 15...Bolt, 20...Tip holding segment, 21...First small segment, 21a...Outer surface, 22...Second small segment, 22a...Outer surface, 23...Third small segment, 23a...Outer surface, 24...Plate, 24a...First part, 24b...Second part, 25...Connecting part, 26...Recess, 27...Flexible part, 28...Bolt, 30...First moving device, 31...Cylinder, 32...Rod, 33...Guide, 35...Fixing device, 35a...First part, 35b...Second part, 36...First connecting member, 37...Shaft, 40...Second moving device, 41...Cylinder, 42...Rod, 43...Second connecting member, 44...Shaft member, 45...Shaft member, 50...Control unit, 51...First operating device, 52...Second operating device, 53...Segment drive device, 54...Drum rotating device, 55...Component supply device

Claims

1. In a molding drum in which a sheet-like rubber material for tires is wrapped around the cylindrical outer surface, Multiple segments are arranged in the circumferential direction of the drum, and the outer surfaces of each of the segments coincide to form the outer circumferential surface of the molding drum. At least one of the multiple segments is a tip-holding segment, The tip-holding segment comprises at least a first sub-segment and a second sub-segment as sub-segments arranged in the circumferential direction of the drum. A molding drum characterized in that the first small segment can take on a first state in which its outer surface coincides with that of the second small segment, and a second state in which at least a portion of the first small segment is positioned radially outward from the second small segment.

2. The molding drum according to claim 1, wherein the tip-holding segment is divided into the first small segment and the second small segment over its entire length in the axial direction of the drum.

3. The molding drum according to claim 1 or 2, wherein the portion of the first subsegment that faces the outer surface of the second subsegment when in the second state is formed as a flexible portion.

4. The molding drum according to claim 1 or 2, wherein a moving device for moving the first small segment from the first state to the second state is arranged radially inward from the first small segment.

5. The molding drum according to claim 1 or 2, wherein a moving device for moving the first small segment from the first state to the second state is provided, the moving device being a first moving device for moving the first small segment in the radial direction of the drum, and a second moving device for moving the first small segment, which has moved outward in the radial direction of the drum, toward the second small segment.

Images