Green tire manufacturing method

Abstract

A method for manufacturing a raw tire. Manufacturing a raw tire with high precision. A method for manufacturing a raw tire (1a) including a joining process (S2). The raw tire includes a second cylindrical body (32A) having a pair of non-contact areas (36, 36). The second cylindrical body has an overlapping portion (33) where a winding start end portion (32a) overlaps with an end end portion (32b). The joining process includes: a first non-contact area joining step (N3) of rolling a first roller (11) on the overlapping portion from the inner end (38i) side of the drum shaft direction of one non-contact area (36A) to the outer end (38e) side and pressing; and a second non-contact area joining step (N4) of rolling a second roller (12) on the overlapping portion from the inner end (39i) side of the drum shaft direction of the other non-contact area (36B) to the outer end side and pressing. The first non-contact area joining step and the second non-contact area joining step are performed at the same timing.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a green tire. Background Art

[0002] Patent Document 1 below describes a method for manufacturing a tire in which a sheet-like inner liner rubber and a sheet-like carcass ply wider than the inner liner rubber are sequentially wound on a forming drum. Both sides of the carcass ply in the width direction extend from the inner liner rubber.

[0003] Patent Document 1: Japanese Patent No. 5281671

[0004] Patent Document 2: International Publication No. 2007 / 007405 Summary of the invention

[0005] On the other hand, it is preferable that the carcass ply has an overlapping portion where a winding start end portion and a winding end end portion overlap, and the start end portion and the end end portion of the overlapping portion are reliably joined by pressing.

[0006] As a method for joining the overlapping portion, it is conceivable to apply the method for manufacturing a carcass ply material described in the above-mentioned Patent Document 2. In the manufacturing method of the above-mentioned Patent Document 2, two sets of roller units are used, one roller unit is moved from the center side of the joining portion of the carcass ply to one side, and the other roller unit is moved from the center side of the joining portion of the carcass ply to the other side. At this time, the other roller unit starts to move later than the one roller unit.

[0007] Here, since the portion of the carcass ply extending from the inner liner rubber is in direct contact with the forming drum, the adhesion to the forming drum is small. Therefore, if the manufacturing method of Patent Document 2 is applied to the joining of the carcass ply, the force generated by the roller units in the width direction acts on the extending portions on both sides with a time difference, causing the carcass ply to be misaligned in the width direction.

[0008] The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide a method for manufacturing a green tire capable of manufacturing the green tire with high precision.

[0009] The present invention is a method for manufacturing a raw tire, which includes: a step of winding a second rubber sheet having a width wider than that of the first rubber sheet on the outer side of a first cylindrical body formed on a drum to form a second cylindrical body having an overlapping portion in which a starting end portion of the winding overlaps with an ending portion; and a joining step of pressing the ending portion toward the starting end portion to join the overlapping portion, the second cylindrical body including a contact area in contact with the first cylindrical body and a pair of non-contact areas extending from the first cylindrical body on both outer sides in the direction of the drum axis, the joining step including: a first non-contact area joining step of rolling a first roller on the overlapping portion from an inner end side of the non-contact area on one side in the direction of the drum axis to an outer end side to press; and a second non-contact area joining step of rolling a second roller on the overlapping portion from an inner end side of the non-contact area on the other side in the direction of the drum axis to press, the first non-contact area joining step and the second non-contact area joining step being performed at the same timing.

[0010] In the method for manufacturing a raw tire of the present invention, preferably, the joining process includes: a first contact area joining step, in which the first roller is rolled on the overlapping portion from the central side of the contact area in the drum axis direction to the inner end of the non-contact area on the one side for pressing; and a second contact area joining step, in which the second roller is rolled on the overlapping portion from the central side of the contact area in the drum axis direction to the inner end of the non-contact area on the other side for pressing, and the second contact area joining step is started later than the first contact area joining step.

[0011] In the method for manufacturing a green tire of the present invention, preferably, the first non-contact region joining step is performed subsequent to the first contact region joining step, and the second non-contact region joining step is performed subsequent to the second contact region joining step.

[0012] In the method for manufacturing a green tire of the present invention, preferably, the pressing force of the first roller in the first non-contact region joining step is greater than the pressing force of the first roller in the first contact region joining step.

[0013] In the green tire manufacturing method of the present invention, preferably, the pressing force of the second roller in the second non-contact region joining step is greater than the pressing force of the second roller in the second contact region joining step.

[0014] In the method for manufacturing a green tire of the present invention, preferably, a moving speed of the second roller in the second contact area joining step is greater than a moving speed of the first roller in the first contact area joining step.

[0015] In the method for manufacturing a green tire of the present invention, preferably, the pressing force of the first roller in the first contact area joining step and the pressing force of the second roller in the second contact area joining step are 0.10 MPa to 0.15 MPa.

[0016] In the green tire manufacturing method of the present invention, preferably, a moving speed of the first roller in the first non-contact area joining step is the same as a moving speed of the second roller in the second non-contact area joining step.

[0017] In the green tire manufacturing method of the present invention, preferably, the pressing force of the first roller in the first non-contact region joining step and the pressing force of the second roller in the second non-contact region joining step are 0.20 MPa to 0.25 MPa.

[0018] In the method for manufacturing a green tire of the present invention, preferably, the first rubber sheet is a rubber material of unvulcanized rubber, and the second rubber sheet is a carcass material in which cords arranged in parallel are covered with unvulcanized rubber.

[0019] In the method for manufacturing a green tire of the present invention, preferably, the first rubber sheet is an inner liner, and the second rubber sheet is a carcass ply.

[0020] In the method for manufacturing a green tire of the present invention, the first non-contact area joining step and the second non-contact area joining step are performed at the same timing. Thus, the non-contact area on one side and the non-contact area on the other side act with opposite forces along the drum axis direction at the same timing, thereby suppressing the positional deviation of the second rubber sheet in the drum axis direction. Therefore, the method for manufacturing a green tire of the present invention can manufacture a green tire with high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a cross-sectional view showing one embodiment of a tire manufactured by the method for manufacturing a green tire of the present invention.

[0022] Figure 2 This is a perspective view showing one embodiment of an apparatus used in the method for manufacturing a green tire of the present invention.

[0023] Figure 3 It is a top view of the drum on which the rubber sheet is wound.

[0024] Figure 4 (a) and (b) are cross-sectional views for explaining the method for manufacturing a green tire of the present invention.

[0025] Figure 5 (a) and (b) are cross-sectional views for explaining the method for manufacturing a green tire of the present invention.

[0026] Description of symbols

[0027] 1a: raw tire; 38i, 39i: inner end; 38e, 39e: outer end; 11: first roller; 12: second roller; S2: joining process; N3: first non-contact area joining step; N4: second non-contact area joining step; 36A: non-contact area on one side; 36B: non-contact area on the other side; 32A: second cylindrical body; 32a: starting end; 32b: terminal end; 33: overlapping portion. DETAILED DESCRIPTION

[0028] Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

[0029] Figure 1 1 is a tire meridian cross-sectional view of a tire 1 manufactured by the green tire manufacturing method of the present embodiment (hereinafter, sometimes simply referred to as “manufacturing method”). Figure 1 The invention also can be used in a method for manufacturing green pneumatic tires for motorcycles, heavy-duty vehicles, and the like, in addition to passenger vehicles.

[0030] like Figure 1 As shown, the tire 1 of this embodiment includes: a carcass 6 extending between the bead portions 4, 4 on both sides; a belt layer 7 arranged on the tire radial direction outer side of the carcass 6 and arranged on the tread portion 2; and an inner liner 8 arranged on the inner side of the carcass 6.

[0031] The carcass 6 of the present embodiment is formed by a carcass ply 6A in which carcass cords (not shown) are arranged at an angle of 70° to 90° relative to the tire circumferential direction. In the present embodiment, the carcass ply 6A includes a main body 6a and a pair of turn-back portions 6b. The main body 6a extends, for example, across between the bead cores 5, 5 buried in the bead portions 4 on both sides. The turn-back portion 6b is connected to the main body 6a and turns back around the bead core 5 from the inner side to the outer side of the tire axial direction. The turn-back portion 6b of the present embodiment has an outer end 6e sandwiched between the belt layer 7 and the main body 6a. In this way, the tire 1 of the present embodiment is formed as a so-called high turn-up structure having a turn-back portion 6b with a large length in the radial direction of the tire.

[0032] The belt layer 7 of this embodiment is formed by two belt plies 7A and 7B arranged inside and outside the tire radial direction. Each belt ply 7A and 7B has, for example, steel cords arranged at an angle of 45° to 75° relative to the tire circumferential direction. The outer end 7e of the inner belt ply 7A in the tire axial direction is closer to the outside of the tread end Te and the outer end 6e of the turn-back portion 6b in the tire axial direction.

[0033] The “tread end Te” is defined as the outermost contact position in the tire axial direction when a standard load is applied to the tire 1 in a standard state and the tire contacts a flat surface at a camber angle of 0 degrees.

[0034] The “standard state” refers to an unloaded state in which the tire 1 is assembled on a standard rim (not shown) and filled with a standard internal pressure.

[0035] The “standard rim” is a rim whose specifications are determined for each tire in a specification system including the specifications to which the tire 1 is based, for example, “standard rim” in JATMA, “design rim” in TRA, and “measuring rim” in ETRTO.

[0036] The “standard internal pressure” refers to the air pressure determined for each tire in each specification in the specification system including the specifications based on which the tire 1 is based. If it is JATMA, it is the “maximum air pressure”; if it is TRA, it is the maximum value recorded in the table “TIRE LOAD LIMITSATVARIOUS COLD INFLATION PRESSURES”; if it is ETRTO, it is “INFLATION PRESSURE”.

[0037] The “standard load” refers to the load specified for each tire in each specification in the specification system including the specifications based on which the tire 1 is based. If it is JATMA, it is the “maximum load capacity”; if it is TRA, it is the maximum value recorded in the table “TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES”; if it is ETRTO, it is “LOADCAPACITY”.

[0038] The inner liner 8 of the present embodiment is formed of butyl rubber having excellent air impermeability. The inner liner 8 is in contact with the main body portion 6a of the carcass ply 6A, for example, and extends between the bead cores 5, 5 on both sides.

[0039] Figure 2 FIG. 1 is a perspective view of an embodiment of the device T used in the manufacturing method of this embodiment. Figure 2 As shown, the device T of this embodiment adopts a well-known device. The device T includes, for example, a drum 10, a first roller 11, and a second roller 12. In addition, in this embodiment, the device T further includes a server 13 and a conveying unit 14.

[0040] The drum 10 of the present embodiment has a cylindrical winding surface 10s. The winding surface 10s of the drum 10 is formed by, for example, a plurality of split dies 16 supported on a rotating shaft 10r of the drum 10. Each split die 16 is supported on the rotating shaft 10r in a manner that allows movement in the radial direction (drum radial direction) of the drum 10. Thus, the winding surface 10s of the present embodiment can expand and contract in the drum radial direction.

[0041] The rotating shaft 10r of the drum 10 is connected to a driving unit (not shown) such as a motor provided on the conveying unit 14. Thus, the winding surface 10s of the drum 10 can rotate via the rotating shaft 10r. The longitudinal direction of the rotating shaft 10r is the axial direction (drum axis direction) X of the drum 10. The rotating shaft 10r of the drum 10 of this embodiment is arranged horizontally.

[0042] The first roller 11 and the second roller 12 of this embodiment are used to press the rubber sheet 30 toward the winding surface 10s. The first roller 11 and the second roller 12 each include a support shaft 17 and a roller sheet 18. The roller sheet 18 is formed of, for example, a flexible resin material and is rotatably supported on the support shaft 17. The width w of the roller sheet 18 ( Figure 3 As shown), for example, it is preferably 5mm to 10mm.

[0043] The support shaft 17 of this embodiment is supported by a known moving tool (not shown) including a known rod cylinder mechanism or a rack and pinion mechanism, etc. Thus, the first roller 11 and the second roller 12 of this embodiment can move in the drum axis direction X or the vertical direction (up and down direction) Y, for example.

[0044] The server 13 of this embodiment is used to supply the rubber sheet 30 to the winding surface 10s of the rotating drum 10. By winding the rubber sheet 30 on the winding surface 10s of the drum 10, the green tire 1a as a tire component is formed.

[0045] Figure 3 FIG. 1 is a top view of the drum 10 and the rubber sheet 30 wound on the drum 10. Figure 3 As shown, the rubber sheet 30 of the present embodiment includes a first rubber sheet 31 and a second rubber sheet 32 ​​having a width wider than the first rubber sheet 31. The second rubber sheet 32 ​​is wound around the outside of the first rubber sheet 31.

[0046] In the present embodiment, the length of the second rubber sheet 32 ​​in the longitudinal direction (the conveying direction of the server 13) is greater than the length of the winding surface 10s of the drum 10 in the drum circumferential direction. Thus, when the second rubber sheet 32 ​​is wound on the drum 10, an overlapping portion 33 is formed where the winding start end portion 32a and the terminal end portion 32b of the second rubber sheet 32 ​​overlap. In the present embodiment, the overlapping portion 33 is formed over the entire width direction of the second rubber sheet 32. For example, the length of the first rubber sheet 31 in the longitudinal direction is preferably greater than the length of the winding surface 10s of the drum 10 in the circumferential direction.

[0047] The first rubber sheet 31 is, for example, an unvulcanized rubber material. In the present embodiment, the first rubber sheet 31 is used in the inner liner 8. The second rubber sheet 32 ​​is, for example, a carcass ply material in which parallel cords are covered with unvulcanized rubber. In the present embodiment, the second rubber sheet 32 ​​is used in the carcass ply 6A.

[0048] like Figure 2 As shown, the transport unit 14 is used to carry the drum 10 into the server 13 and to carry the drum 10 out of the server 13. The transport unit 14 can move along a track 19 or the like provided on the floor, for example.

[0049] Next, the manufacturing method of the present embodiment is described. The manufacturing method of the present embodiment includes a forming step S1 and a joining step S2. In the forming step S1, the second cylindrical body 32A is formed outside the first cylindrical body 31A formed on the drum 10.

[0050] Figure 4 (a) is a cross-sectional view of the drum 10 for explaining the forming step S1. Figure 4 As shown in (a) of FIG. 1 , in the present embodiment, the first cylindrical body 31A is formed by winding the first rubber sheet 31 on the winding surface 10s of the drum 10. The first rubber sheet 31 is wound on the winding surface 10s by, for example, being fed to the rotating drum 10 by the server 13. The winding terminal end (not shown) is joined to the first rubber sheet 31 by, for example, the first roller 11 or the second roller 12.

[0051] In the forming step S1 of the present embodiment, the second rubber sheet 32 ​​is then conveyed to the rotating drum 10 by, for example, the server 13 and wound on the winding surface 10s and the first cylindrical body 31A, thereby forming the second cylindrical body 32A. At this time, the starting end 32a and the terminal end 32b overlap in the drum radial direction. The overlapping portion 33 is preferably arranged in a manner such that it is located at the uppermost side in the vertical direction. The length L1 ( Figure 2 The width w of the roller sheet 18 is preferably smaller than that of the roller sheet 18, for example, about 3 mm to 6 mm. At this time, the first roller 11 and the second roller 12 are restricted to a position away from the drum 10.

[0052] The second cylindrical body 32A includes a contact area 35 in contact with the first cylindrical body 31A and a pair of non-contact areas 36, 36 extending from the first cylindrical body 31A to both sides in the drum axis direction X. The non-contact areas 36, 36 are formed so that their lengths L2 in the drum axis direction X are the same. In this specification, the non-contact area on one side (the left side in the figure) is the first non-contact area 36A, and the non-contact area on the other side (the right side in the figure) is the second non-contact area 36B.

[0053] Next, the bonding step S2 is performed. The bonding step S2 of the present embodiment includes a first contact region bonding step N1, a second contact region bonding step N2, a first non-contact region bonding step N3, and a second non-contact region bonding step N4.

[0054] Figure 4 (b) is a cross-sectional view of the drum 10 for explaining the first contact area joining step N1. Figure 4 As shown in (b), the first contact area joining step N1 of the present embodiment causes the first roller 11 to roll on the overlapping portion 33 from the center side of the contact area 35 in the drum axis direction X to the inner end 38i of the first non-contact area 36A and press. In the first contact area joining step N1, for example, the moving tool not shown in the figure is operated, and the first roller 11 contacts the center of the contact area 35 of the overlapping portion 33 in the drum axis direction X, so that the second rubber sheet 32 ​​is pressed on the drum 10. Then, for example, the moving tool is operated, and the first roller 11 moves while pressing toward the first non-contact area 36A side along the drum axis direction X. In this first contact area joining step N1, the moving speed (drum axis direction X) of the first roller 11 is set to v1. In addition, when the first rubber sheet 31 is the carcass ply 6A, the pressing force p1 of the first roller 11 is preferably 0.10MPa to 0.15MPa. At this time, in order to avoid contact with the first roller 11, the second roller 12 is restricted to a position away from the drum 10.

[0055] Next, the second contact region bonding step N2 is performed. Figure 5 (a) is a cross-sectional view of the drum 10 for explaining the second contact area joining step N2. Figure 5 As shown in (a), the second contact area joining step N2 causes the second roller 12 to roll on the overlapping portion 33 from the center side of the contact area 35 in the drum axis direction X to the inner end 39i of the second non-contact area 36B and press. In the second contact area joining step N2, for example, the moving tool not shown in the figure is operated, and the second roller 12 contacts the center of the contact area 35 of the overlapping portion 33 in the drum axis direction X, so that the second rubber sheet 32 ​​is pressed on the drum 10. At this time, it is preferred that the second roller 12 is pressed at the same position as the position where the first roller 11 initially pressed the second rubber sheet 32. Next, for example, the moving tool is operated to move the second roller 12 along the drum axis direction X toward the second non-contact area 36B side while pressing. The second contact area joining step N2 starts, for example, when the first roller 11 is moving in the contact area 35.

[0056] Thus, the second contact region joining step N2 is started later than the first contact region joining step N1, for example, to avoid contact between the first roller 11 and the second roller 12 and to keep the first pressing position on the second rubber sheet 32 ​​at the same position, thereby firmly joining the second rubber sheet 32.

[0057] In the second contact region joining step N2, the moving speed v2 (drum axis direction X) of the second roller 12 is set faster than the moving speed v1 of the first roller 11. The pressing force p2 of the second roller 12 is preferably the same as the pressing force p1 of the first roller 11, for example, set to 0.10 MPa to 0.15 MPa.

[0058] Next, the first non-contact region bonding step N3 and the second non-contact region bonding step N4 are started. Figure 5 (b) is a cross-sectional view of the drum 10 for explaining the first non-contact area joining step N3 and the second non-contact area joining step N4. Figure 5 As shown in (b), the first non-contact area joining step N3 rolls the first roller 11 from the inner end 38i side of the first non-contact area 36A in the drum axis direction X to the outer end 38e side to press on the overlapping portion 33. The second non-contact area joining step N4 rolls the second roller 12 from the inner end 39i side of the second non-contact area 36B in the drum axis direction X to the outer end 39e side to press on the overlapping portion 33.

[0059] The first non-contact area joining step N3 and the second non-contact area joining step N4 are performed at the same timing. As a result, the first non-contact area 36A and the second non-contact area 36B act in opposite directions along the drum axis direction X at the same timing, thereby suppressing the positional deviation of the second rubber sheet 32 ​​in the drum axis direction X. Therefore, the manufacturing method of this embodiment can manufacture the raw tire 1a with high precision. The "same timing" means that the moment when the first roller 11 passes through the inner end 38i of the first non-contact area 36A is the same as the moment when the second roller 12 passes through the inner end 39i of the second non-contact area 36B. In addition, the "same timing" includes the deviation of the moment to the extent that the effect of suppressing the positional deviation of the second rubber sheet 32 ​​in the drum axis direction X is exerted, for example, including the case where the deviation of the moment is within 2 seconds.

[0060] In order to perform the first non-contact region joining step N3 and the second non-contact region joining step N4 at the same timing, the moving speed v2 of the second roller 12 in the second contact region joining step N2 is made faster than the moving speed v1 of the first roller 11 in the first contact region joining step N1. Although it is determined by the length L3 of the contact region 35 in the drum axis direction (the width of the first rubber sheet 31), it is preferred that the moving speed v2 of the second roller 12 is 30 mm / sec to 50 mm / sec faster than the moving speed v1 of the first roller 11, for example.

[0061] Preferably, the moving speed V1 of the first roller 11 in the first non-contact region joining step N3 is the same as the moving speed V2 of the second roller 12 in the second non-contact region joining step N4. Thus, the timing of the first roller 11 and the second roller 12 passing through the outer ends 38e and 39e is also the same, and the first roller 11 and the second roller 12 act in opposite directions along the drum axis direction X in the entire area of ​​the first non-contact region 36A and the second non-contact region 36B. Thus, the positional deviation of the second rubber sheet 32 ​​in the drum axis direction X is further suppressed.

[0062] Although not particularly limited, it is preferred that the moving speed V2 of the second roller 12 in the second non-contact region joining step N4 is the same as the moving speed v2 of the second roller 12 in the second contact region joining step N2. In this case, the moving speed V1 of the first roller 11 in the first non-contact region joining step N3 is faster than the moving speed v1 of the first roller 11 in the first contact region joining step N1.

[0063] The moving speed v1 of the first roller 11 is preferably 140 mm / sec to 200 mm / sec, for example, although it is determined by the length L3 of the contact area 35 in the drum axis direction. In addition, the moving speed V1 of the first roller 11, the moving speed v2 of the second roller 12, and the moving speed V2 of the second roller 12 are preferably 190 mm / sec to 250 mm / sec.

[0064] In addition, the moving speeds v1, v2, V1, and V2 in each step N1 to N4 are not limited to the above-mentioned method. Since the first non-contact area joining step N3 and the second non-contact area joining step N4 are performed at the same timing. Moreover, the moving speed V1 of the first roller 11 in the first non-contact area joining step N3 is the same as the moving speed V2 of the second roller 12 in the second non-contact area joining step N4. As long as these regulations are met, other moving speeds can be selected separately.

[0065] In order to effectively exert the above-mentioned effect, it is preferable that the pressing force P1 of the first roller 11 in the first non-contact area joining step N3 and the pressing force P2 of the second roller 12 in the second non-contact area joining step N4 are the same. In the case where the second rubber sheet 32 ​​is the carcass ply 6A, the pressing force P1 of the first roller 11 in the first non-contact area joining step N3 and the pressing force P2 of the second roller 12 in the second non-contact area joining step N4 are preferably 0.20 MPa to 0.25 MPa.

[0066] In the joining process S2 of the present embodiment, the first non-contact area joining step N3 is performed following the first contact area joining step N1. In addition, the second non-contact area joining step N4 is performed following the second contact area joining step N2. That is, the joining process S2 is performed, for example, from the first contact area joining step N1 to the first non-contact area joining step N3 without stopping the first roller 11. In addition, the joining process S2 is performed, for example, from the second contact area joining step N2 to the second non-contact area joining step N4 without stopping the second roller 12.

[0067] In the present embodiment, the second contact area joining step N2 starts later than the first contact area joining step N1. Then, the first non-contact area joining step N3 is performed following the first contact area joining step N1, and the second non-contact area joining step N4 is performed following the second contact area joining step N2. However, the present invention is not limited to such a manner. For example, the first non-contact area joining step N3 and the second non-contact area joining step N4 may also start at the same timing, and then start in the order of the first contact area joining step N1 and the second contact area joining step N2. In this case, it is preferred that the moving speed V1 of the first roller 11 of the first non-contact area joining step N3 is the same as the moving speed V2 of the second roller 12 of the second non-contact area joining step N4. In addition, the moving speed v1 of the first roller 11 of the first contact area joining step N1 and the moving speed v2 of the second roller 12 of the second contact area joining step N2 may also be the same.

[0068] As mentioned above, although the particularly preferred embodiment of the present invention has been described in detail, the present invention is not limited to the illustrated embodiment, and can be implemented in various modified forms.

[0069] [Example]

[0070] use Figure 2 A green tire was manufactured by using a device having a second cylindrical body composed of a second rubber sheet (carcass ply) formed on the outside of a first cylindrical body composed of a first rubber sheet (inner liner). Furthermore, the molding accuracy of the second cylindrical body of the green tire was tested. The test method and general specifications are as follows.

[0071] Length of each non-contact area in the drum axis direction: 140mm

[0072] <Molding accuracy>

[0073] The tester measures the positional offset of the second rubber sheet relative to the first rubber sheet in the drum axis direction. The results are expressed as measured values, and less than 5 mm is considered good. The results are shown in Table 1.

[0074] In the embodiment, the first non-contact area joining step and the second non-contact area joining step are started at the same timing. In the comparative example, the first non-contact area joining step and the second non-contact area joining step are started at different timings.

[0075]

Table 1

[0076]

[0077] It was confirmed that the manufacturing method of the example was superior in molding accuracy compared to the manufacturing method of the comparative example.

Claims

1. A method for manufacturing a green tire, wherein: Include: A step of winding a second rubber sheet having a width wider than that of the first rubber sheet around the outside of a first cylindrical body of a first rubber sheet formed on a drum to form a second cylindrical body having an overlapping portion in which a starting end portion and an ending end portion of the winding overlap each other; as well as a joining step of pressing the terminal portion toward the starting end portion to join the overlapping portions, The second cylindrical body includes a contact area in contact with the first cylindrical body and a pair of non-contact areas extending from the first cylindrical body on both sides in the drum axis direction. The bonding process comprises: A first non-contact area joining step of rolling the first roller on the overlapping portion from the inner end side to the outer end side of the drum axis direction of one of the non-contact areas to press; as well as The second non-contact area joining step comprises rolling the second roller on the overlapping portion from the inner end side to the outer end side of the drum axis direction of the other non-contact area to press, The first non-contact area bonding step and the second non-contact area bonding step are performed at the same timing, The bonding process comprises: A first contact area joining step of rolling the first roller on the overlapping portion from the center side of the contact area in the drum axis direction to the inner end of the non-contact area on one side to press; as well as The second contact area joining step includes rolling the second roller on the overlapping portion from the center side of the contact area in the drum axis direction to the inner end of the other non-contact area to press, The second contact area joining step is started later than the first contact area joining step.

2. The method for manufacturing a green tire according to claim 1, wherein: The first non-contact region bonding step is performed subsequent to the first contact region bonding step. The second non-contact region bonding step is performed subsequent to the second contact region bonding step.

3. The method for manufacturing a green tire according to claim 1 or 2, wherein: The pressing force of the first roller in the first non-contact region bonding step is greater than the pressing force of the first roller in the first contact region bonding step.

4. The method for manufacturing a green tire according to claim 1 or 2, wherein: The pressing force of the second roller in the second non-contact area bonding step is greater than the pressing force of the second roller in the second contact area bonding step.

5. The method for manufacturing a green tire according to claim 1 or 2, wherein: A moving speed of the second roller in the second contact area joining step is greater than a moving speed of the first roller in the first contact area joining step.

6. The method for manufacturing a green tire according to claim 1 or 2, wherein: The pressing force of the first roller in the first contact region bonding step and the pressing force of the second roller in the second contact region bonding step are 0.10 MPa to 0.15 MPa.

7. The method for manufacturing a green tire according to claim 1 or 2, wherein: A moving speed of the first roller in the first non-contact area joining step is the same as a moving speed of the second roller in the second non-contact area joining step.

8. The method for manufacturing a green tire according to claim 1 or 2, wherein: The pressing force of the first roller in the first non-contact region bonding step and the pressing force of the second roller in the second non-contact region bonding step are 0.20 MPa to 0.25 MPa.

9. The method for manufacturing a green tire according to claim 1 or 2, wherein: The first rubber sheet is a rubber material of unvulcanized rubber, The second rubber sheet is a cord layer material in which cords arranged in parallel are covered with unvulcanized rubber.

10. The method for manufacturing a green tire according to claim 9, wherein: The first rubber sheet is an inner lining layer, The second rubber sheet is a carcass ply.

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