Bead manufacturing method and bead manufacturing apparatus

Abstract

Provided are a bead manufacturing method and a bead manufacturing apparatus capable of manufacturing, with high productivity, a bead in which the surface of a bead core is covered with a sheet material even if the specification of the bead core varies. When a portion in the circumferential direction of an annular bead core Bc mounted around a drum body 8 is pressed by using a pressing roller 13 toward a circumferential groove 8b formed in the outer circumferential surface of the drum body 8 to be externally fitted to the circumferential groove 8b, a sheet material Bs is sandwiched between the portion in the circumferential direction of the bead core Bc and the circumferential groove 8b to press-bond the sheet material Bs to the portion in the circumferential direction, the sheet material Bs is pulled out by a prescribed length along the circumferential groove 8b by the rotation of the drum body 8 and the bead core Bc, both end portions of the sheet material Bs in the width direction extending in the circumferential direction on the outer circumferential surface of the drum body 8 are folded back by folding back guides 14a, 14b to be press-bonded to the surface of the bead core Bc, and the surface of the bead core Bc is covered with the sheet material Bs over the entire length in the circumferential direction.

Description

Method and apparatus for manufacturing beads

[0001] The present invention relates to a method and an apparatus for manufacturing beads, and more particularly, to a method and an apparatus for manufacturing beads that can produce beads with various specifications of bead cores, whose surfaces are covered with a sheet material, with high productivity.

[0002] Various methods are known for attaching and covering a sheet material to the surface of an annular bead core that constitutes a tire (see, for example, Patent Document 1). In the method proposed in Patent Document 1, starting from the position where a sheet material (tape) is attached to the inner peripheral surface of the bead core by a pressure roller as the starting end (Fig. 8(a)), this sheet material is sequentially attached to the surface of the continuously rotating bead core. Thereby, the surface of the bead core is covered with the sheet material.

[0003] Although the bead core is formed of a metal wire, its surface has adhesiveness if it is covered with, for example, unvulcanized rubber. In the method proposed in Patent Document 1, the starting end of the sheet material can be fixed to the bead core in the case of a specification with strong adhesiveness, but it cannot be firmly fixed in the case of a specification with weak adhesiveness. Also, in a bead core composed only of a metal wire, it is difficult to fix the starting end of the sheet material to the surface of the bead core in the first place. If the starting end of the sheet material cannot be firmly fixed to the surface of the bead core, the surface of the bead core cannot be stably and reliably covered with the sheet material. Therefore, there is room for improvement in producing beads with various specifications of bead cores, whose surfaces are covered with a sheet material, with high productivity.

[0004] Japanese Patent Application Laid-Open No. 8-47984

[0005] The object of the present invention is to provide a method and an apparatus for manufacturing beads that can produce beads with various specifications of bead cores, whose surfaces are covered with a sheet material, with high productivity.

[0006] To achieve the above objective, the present invention provides a method for manufacturing a bead, in which a sheet material is attached to the surface of an annular bead core and the surface is covered with the sheet material, wherein a circumferential groove extending in the circumferential direction is formed on the outer surface of a drum body having a diameter smaller than the inner diameter of the bead core, the bead core is fitted onto the drum body, and a portion of the bead core in the circumferential direction is pressed toward the circumferential groove with a pressure roller and fitted into the circumferential groove, and the drum body is rotated around the drum axis to rotate the bead core, thereby sequentially fitting the bead core into the circumferential groove along its entire circumferential length. The present invention relates to a method for fitting a portion of the bead core in the circumferential groove, wherein the sheet material supplied to the outer circumferential surface is sandwiched between the portion and the circumferential groove and pressed against the portion, the sheet material is pulled out to a predetermined length along the circumferential groove by the rotating drum and the bead core, and both ends of the sheet material extending in the width direction circumferentially on the outer circumferential surface are folded back toward the bead core in the fitted state in the circumferential groove and pressed against the surface of the bead core, thereby covering the surface of the bead core with the sheet material over its entire circumferential length.

[0007] The bead manufacturing apparatus of the present invention has a pressure roller for pressing and attaching a sheet material to the surface of an annular bead core, and manufactures a bead whose surface is covered with the sheet material, comprising: a drum body having a diameter smaller than the inner diameter of the bead core; a folding guide for folding back the sheet material; and a supply source for supplying the sheet material to the outer circumferential surface of the drum body, wherein a circumferential groove extending in the circumferential direction is formed on the outer circumferential surface, and a circumferential portion of the bead core fitted onto the drum body is pressed toward the circumferential groove by the pressure roller and fitted into the circumferential groove, and the bead core rotates by rotating the drum body around the drum axis, thereby manufacturing the bead The bead core is configured to be fitted sequentially into the circumferential groove along its entire circumferential length, and the sheet material supplied to the outer circumferential surface is sandwiched between the circumferential portion fitted into the circumferential groove and the circumferential groove, and pressed against the circumferential portion, and the sheet material is drawn out to a predetermined length along the circumferential groove by the rotation of the drum body and the bead core, and both widthwise ends of the drawn-out sheet material that extend circumferentially on the outer circumferential surface are folded back by the folding guide toward the bead core fitted into the circumferential groove and pressed against the surface of the bead core, so that the surface of the bead core is covered with the sheet material along its entire circumferential length.

[0008] According to the present invention, the sheet material supplied to the outer circumferential surface is sandwiched between the circumferential portion fitted into the circumferential groove and the circumferential groove, and is pressed against the circumferential portion. Therefore, regardless of the adhesive strength of the surface of the bead core, the starting end of the sheet material when covering the bead core can be stably and firmly fixed to the surface of the bead core. Therefore, by rotating the drum body around the drum axis to rotate the bead core and sequentially fitting the bead core into the circumferential groove along its entire circumferential length, it is advantageous for productively manufacturing beads in which the surface of the bead core is covered with the sheet material.

[0009] Figure 1 is an explanatory diagram illustrating an embodiment of a bead manufacturing apparatus in a side view. Figure 2 is an explanatory diagram illustrating the bead manufacturing apparatus of Figure 1 in a front view. Figure 3 is an explanatory diagram illustrating the state of bead manufacturing by the bead manufacturing apparatus of Figure 2. Figure 4 is an explanatory diagram illustrating the area around the press roller of Figure 3 in a top view. Figure 5 is an explanatory diagram illustrating the area around the outer surface of the drum body in the direction of arrow A in Figure 3. Figure 6 is an explanatory diagram illustrating the area around the supply guide of Figure 3 in a cross view. Figure 7 is an explanatory diagram illustrating the area around the press roller of Figure 3 in a cross view. Figure 8 is an explanatory diagram illustrating the area around the pressing jig of Figure 3 in a cross view. Figure 9 is an explanatory diagram illustrating the area around the upper crimping roller of Figure 3 in a cross view. Figure 10 is an explanatory diagram illustrating the area around the upper folding guide of Figure 3 in a cross view. Figure 11 is an explanatory diagram illustrating the area around the middle crimping roller of Figure 3 in a cross view. Figure 12 is an explanatory diagram illustrating a cross-sectional view of the area around the lower folding guide in Figure 3. Figure 13 is an explanatory diagram illustrating a cross-sectional view of the area around the lower crimping roller in Figure 3.

[0010] The bead manufacturing method and apparatus of the present invention will be described in detail below based on the embodiments shown in the figures.

[0011] Using the embodiment of the bead manufacturing apparatus 1 illustrated in Figures 1 to 5, a bead B is manufactured in which the surface of an annular bead core Bc is covered with a sheet material Bs. Since bead B is a component of the tire, its specifications are determined according to tire performance, tire size, etc.

[0012] The bead core Bc is formed from metal wires such as steel wire, and various known specifications can be used. The sheet material Bs is formed by impregnating a fibrous fabric with RFL liquid (resorcinol, formalin, latex liquid), and has some adhesive properties. Various known specifications can be used for the sheet material Bs. The width of the sheet material Bs is set to be slightly longer than the perimeter of the surface in the cross-section of the bead core Bc.

[0013] The manufacturing apparatus 1 comprises a drum body 8 with a diameter smaller than the inner diameter of the annular bead core Bc, pressure rollers 13 (13a, 13b, 13c) for pressing and attaching sheet material Bs to the surface of the bead core Bc, folding guides 14 (14a, 14b) for folding back the sheet material Bs, a supply reel 2 which serves as a supply source for supplying sheet material Bs to the outer circumference of the cylindrical drum body 8, and a control unit 17. The operation of various components of the manufacturing apparatus 1 is controlled by the control unit 17. A known computer is used for the control unit 17.

[0014] A circumferential groove 8b is formed on the outer surface of the drum body 8, which rotates around the drum shaft 8a, extending along its entire circumferential length. The supply path for the sheet material Bs is from the supply reel 2 to the drum body 8. Numerous support rollers are arranged along this supply path, and the sheet material Bs is stretched across these support rollers. The arrows X and Y in the figure indicate the front-to-back and width directions of the manufacturing apparatus 1, respectively. The X and Y directions are perpendicular to each other. The dashed line CL indicates the widthwise center of the drum body 8, and the dashed line Z indicates the axis of the drum shaft 8a of the drum body 8. The width direction of the drum body 8 is the X direction, and the drum shaft 8a extends in the X direction.

[0015] The sheet material Bs is wound onto the supply reel 2 around a support shaft 2a that extends in the Y direction. Downstream of the supply of the sheet material Bs relative to the supply reel 2, the following components are arranged in order: a drive roller 3, a festoon section 4, a perforation section 5, a length adjustment mechanism 6, and a direction changing roller 7. The area downstream of the direction changing roller 7 in the supply path will be described later.

[0016] The direction-changing roller 7 changes the orientation of the supply path by 90° in a plan view. Therefore, the pivot shaft 2a (axis) of the supply reel 2 and the drum axis 8a (axis) of the drum body 8 are perpendicular in a plan view. If the pivot shaft 2a (axis) of the supply reel 2 and the drum axis 8a (axis) of the drum body 8 were configured to be parallel, the space required for installing the manufacturing device 1 would be excessive. For this reason, by using the direction-changing roller 7 to change the orientation of the supply path by 90° midway, the manufacturing device 1 is made more compact.

[0017] The drive roller 3, which is rotationally driven by an electric motor or the like, rotates the supply reel 2 around the support shaft 2a, thereby unloading the sheet material Bs from the supply reel 2. The sheet material Bs unloaded from the supply reel 2 in this manner is supplied toward the outer surface of the drum body 8 by the rotation of the drum body 8. The festoon section 4 has support rollers that are spaced apart vertically, and by stretching the sheet material Bs across these support rollers, it ensures the excess length of the sheet material Bs and also functions to apply a moderate and constant tension to the sheet material Bs stretched across it.

[0018] The perforation unit 5 has a blade portion 5a and a receiving portion 5b, and the blade portion 5a moves toward and away from the receiving portion 5b. As the blade portion 5a moves toward the receiving portion 5b, perforations are made in the sheet material Bs that passes between the blade portion 5a and the receiving portion 5b, transversely in the width direction. Various known specifications can be adopted for the perforation unit 5.

[0019] The length adjustment mechanism 6 has a support roller that moves up and down and adjusts the length of the sheet material Bs supplied to the drum body 8 to cover one bead core Bc. When the support roller 6 moves downward, the length of the sheet material Bs for one bead core Bc increases, and when it moves upward, the length of the sheet material Bs for one bead core Bc decreases. A predetermined length L of the sheet material Bs required to cover one bead core Bc is set in advance, and the length adjustment mechanism 6 is controlled according to this predetermined length L. This predetermined length L is set to be slightly longer than the total circumferential length of the bead core Bc.

[0020] Downstream of the direction-changing roller 7 in the supply path, a supply guide 9, a pressing roller 11, and a pressing jig 12 are arranged in that order. The supply guide 9, pressing roller 11, and pressing jig 12 are positioned above the drum body 8 and close to the outer surface of the drum body 8. A sheet presser 10 is positioned above the supply guide 9. The pressing jig 12 and sheet presser 10 can be provided as optional.

[0021] As illustrated in Figure 4, the supply guide 9 is a plate-like body having protruding edges at both ends, and these edges are spaced apart in the width direction of the drum body 8. The spacing between the protruding edges at both ends of the supply guide 9 is set to be slightly larger than the width dimension of the sheet material Bs. The supply guide 9 guides the sheet material Bs through and along the circumferential groove 8b, supplying it to the outer surface of the drum body 8. In this embodiment, since the circumferential groove 8b is formed in the center in the width direction of the outer surface of the drum body 8, the supply guide 9, sheet presser 10, presser roller 11, and pressing jig 12 are arranged according to the position of the circumferential groove 8b.

[0022] The sheet retainer 10 is a plate-like body made of, for example, metal or hard resin, and moves closer to and away from the supply guide 9. When the sheet retainer 10 moves closer to the supply guide 9, the sheet material Bs passing between the sheet retainer 10 and the supply guide 9 is sandwiched and fixed between the sheet retainer 10 and the supply guide 9 (the supply movement of the sheet material Bs is stopped).

[0023] The rotatable press roller 11 presses the sheet material Bs, guided by the supply guide 9, against the outer circumferential surface of the drum body 8. The sheet material Bs extends across the circumferential groove 8b to the outer circumferential surface of the drum body 8. In this embodiment, two press rollers 11, pivotally supported on one shaft, are spaced apart in the drum width direction, and these press rollers 11 press the sheet material Bs against the outer circumferential surface of the drum body 8 at positions straddling the circumferential groove 8b. It is preferable that the press rollers 11 be designed to press both ends of the sheet material Bs in the width direction so that the sheet material Bs does not lift up. The press rollers 11 are not limited to two as in this embodiment; a single press roller 11 can also be used to press the sheet material Bs across the circumferential groove 8b.

[0024] The pressing jig 12 presses the sheet material Bs into the circumferential groove 8b. More specifically, the pressing jig 12 guides the center of the sheet material Bs in the width direction into the circumferential groove 8b and presses it in place. The pressing jig 12 can be made of metal or hard resin and should be designed to press the sheet material Bs into the circumferential groove 8b. As illustrated in Figure 4, the width of the sheet material Bs placed on the outer surface of the drum body 8 is reduced by the amount that the center of the sheet material Bs in the width direction is pressed into the circumferential groove 8b by the pressing jig 12.

[0025] Next, we will describe the other components located on the outer circumference of the drum body 8.

[0026] Following the supply guide 9, sheet presser 10, presser roller 11, and pressing jig 12, the outer circumference of the drum body 8 is arranged with crimping rollers 13 (13a, 13b, 13c) and folding guides 14 (14a, 14b). More specifically, the crimping rollers 13a, 13b, and 13c are arranged sequentially at intervals in the circumferential direction toward the downstream side in the supply direction of the sheet material Bs. One folding guide 14a is positioned between crimping rollers 13a and 13b, and the other folding guide 14b is positioned between crimping rollers 13b and 13c.

[0027] A pair of guide rollers 16a and 16b are positioned opposite the crimping roller 13 and the folding guide 14, with the drum body 8 in between. The rotatable guide rollers 16a and 16b are spaced apart in the width direction of the manufacturing apparatus 1, and the guide rollers 16a and 16b move together in the width direction of the manufacturing apparatus 1. The bead core Bc, which is fitted onto the drum body 8, passes between the pair of guide rollers 16a and 16b.

[0028] As illustrated in Figure 2, the crimping roller 13 and the folding guide 14 are fixed to a movable frame 15 that moves closer to and away from the outer circumferential surface of the drum body 8. Therefore, by moving the movable frame 15 closer to the outer circumferential surface of the drum body 8, the crimping roller 13 and the folding guide 14 move closer to the outer circumferential surface of the drum body 8.

[0029] As illustrated in Figure 5, the crimping roller 13 is a rotatable roller positioned across the circumferential groove 8b. The outer surface of the crimping roller 13 and the outer surface of the drum body 8 face each other. The crimping roller 13 presses the sheet material Bs onto the surface of the bead core Bc, as will be described later.

[0030] As illustrated in Figure 2, the folding guide 14 has an arc-shaped plate that follows the outer circumferential surface of the drum body 8. As illustrated in Figure 5, one folding guide 14a is positioned unevenly on one side in the width direction of the circumferential groove 8b, and the other folding guide 14b is positioned unevenly on the other side in the width direction of the circumferential groove 8b. The folding guides 14a and 14b fold both ends of the sheet material Bs in the width direction toward the bead core Bc, as will be described later.

[0031] Next, we will explain an example of the procedure for manufacturing bead B using this manufacturing apparatus 1.

[0032] First, as illustrated in Figure 2, the bead core Bc is externally fitted onto the drum body 8 with the movable frame 15 separated from the outer circumferential surface of the drum body 8. Using a known transfer device that can grip and move the bead core Bc, the bead core Bc is inserted between a pair of guide rollers 16a and 16b and externally fitted onto the drum body 8. The bead core Bc is positioned so that its widthwise position on the drum body 8 coincides with the circumferential groove 8b.

[0033] Next, as illustrated in Figure 3, the movable frame 15 is moved closer to the outer surface of the drum body 8, and the crimping roller 13 presses against the outer surface of the bead core Bc. This presses a portion of the bead core Bc in the circumferential direction (the portion corresponding to the area from the upper crimping roller 13a to the lower crimping roller 13c) toward the circumferential groove 8b, causing it to be fitted into the circumferential groove 8b. Furthermore, the pair of guide rollers 16a and 16b are moved together toward the other guide roller 16b, and the inner surface of the bead core Bc is pressed by one of the guide rollers 16a. By maintaining the pair of guide rollers 16a and 16b in this position, a force acts on the bead core Bc in the direction toward the other guide roller 16b (Y direction), stably extrapolating the bead core Bc to the drum body 8.

[0034] With the bead core Bc externally fitted onto the drum body 8 in this manner, when the drum body 8 is rotated around the drum shaft 8a, the bead core Bc rotates along with the drum body 8. A portion of the bead core Bc that is fitted externally into the circumferential groove 8b comes out of the circumferential groove 8b when it passes through the crimping roller 13c. Therefore, as the bead core Bc continues to rotate along with the drum body 8, the bead core Bc is sequentially fitted externally into the circumferential groove 8b along its entire circumferential length.

[0035] In the supply path, the starting end (longitudinal tip) of the sheet material Bs is extended slightly downstream from the pressing jig 12 (for example, between the pressing jig 12 and the crimping roller 13a). Then, the starting end of the sheet material Bs is sandwiched between the outer surface of the drum body 8 and the pressing roller 11.

[0036] As illustrated in Figure 3, when the drum body 8 is rotated around the drum shaft 8a with the starting end of the sheet material Bs sandwiched between the outer surface of the drum body 8 and the pressing roller 11, the sheet material Bs, which is pressed against the outer surface of the drum body 8 by the pressing roller 11, is pulled out towards the pressing roller 13a after passing through the pressing jig 12.

[0037] The crimping roller 13 has a portion of the bead core Bc fitted into the circumferential groove 8b. As a result, the starting end of the sheet material Bs pulled out toward the crimping roller 13a is sandwiched between the bead core Bc, which is fitted into the circumferential groove 8b, and the circumferential groove 8b, and is pressed against the bead core Bc. Therefore, the pulled-out sheet material Bs is sandwiched between the portion of the bead core Bc that is fitted into the circumferential groove 8b and the circumferential groove 8b, and is pressed against this portion. In this state, the rotating drum body 8 and bead core Bc pull out the sheet material Bs along the circumferential groove 8b at substantially the same speed as the rotational speed of the drum body 8 (circumferential speed of the outer surface), without shifting relative to the outer surface of the drum body 8. The rotation of the drum body 8 and bead core Bc is configured to pull out a predetermined length L of sheet material Bs along the circumferential groove 8b. The surface of the bead core Bc is covered by the sheet material Bs of a predetermined length L that has been drawn out, along its entire circumferential length.

[0038] The process of covering the surface of the bead core Bc with sheet material Bs along its entire circumferential length will be described in detail with reference to Figures 6 to 13.

[0039] As illustrated in Figure 6, the sheet material Bs is supplied to the outer surface of the drum body 8 by the supply guide 9, while its displacement in the width direction is restricted. Next, as illustrated in Figure 7, the sheet material Bs that has passed through the supply guide 9 is pressed against the outer surface of the drum body 8 by the press roller 11. Next, as illustrated in Figure 8, the sheet material Bs pressed against the outer surface of the drum body 8 is pushed toward the circumferential groove 8b by the pressing jig 12. The pushed sheet material Bs takes on a shape that conforms to the cross-sectional shape of the circumferential groove 8b. In this embodiment, the sheet material Bs is not in contact with the bottom of the circumferential groove 8b.

[0040] Next, as illustrated in Figure 9, at the position of the crimping roller 13a, the outer surface of the bead core Bc is pressed by the crimping roller 13a, and the bead core Bc is fitted into the circumferential groove 8b. Since the sheet material Bs is interposed between the bead core Bc and the circumferential groove 8b, the sheet material Bs is sandwiched between the bead core Bc and the circumferential groove 8b and pressed against the inner surface of the bead core Bc. When the starting end of the sheet material Bs is sandwiched between the bead core Bc and the circumferential groove 8b, the presser roller 11 moves away from the outer surface of the drum body 8, releasing the pressure of the sheet material Bs against the outer surface of the drum body 8 by the presser roller 11.

[0041] The specifications (size and cross-sectional shape) of the circumferential groove 8b are set according to the specifications (size and cross-sectional shape) of the bead core Bc, but even with a single specification of circumferential groove 8b, it is possible to accommodate multiple specifications of bead core Bc. When the sheet material Bs is sandwiched between the bead core Bc and the circumferential groove 8b, it is preferable that about half of the cross-section of the bead core Bc protrudes outward from the outer circumferential surface of the drum body 8. That is, in the cross-section of the bead core Bc, for example, 30% to 70%, more preferably 40% to 60%, of the thickness of the bead core Bc should protrude from the outer circumferential surface of the drum body 8. If the thickness of the bead core Bc that protrudes from the outer circumferential surface of the drum body 8 is excessive (i.e., the bead core Bc is shallowly fitted into the circumferential groove 8b), it becomes slightly disadvantageous to stably press the sheet material Bs against the inner circumferential surface of the bead core Bc. If the thickness of the bead core Bc protruding from the outer surface of the drum body 8 is insufficient (i.e., if the bead core Bc is deeply fitted into the circumferential groove 8b), it becomes difficult to smoothly remove the bead core Bc from the circumferential groove 8b.

[0042] Next, as illustrated in Figure 10, one end of the sheet material Bs extending circumferentially on the outer surface of the drum body 8 is folded back towards the bead core Bc, which is fitted into the circumferential groove 8b, using one of the folding guides 14a. This presses the folded portion of the sheet material Bs against the surface of the bead core Bc.

[0043] Next, as illustrated in Figure 11, the outer circumferential surface of the bead core Bc, on which the sheet material Bs has been folded, is pressed by the crimping roller 13b. This ensures that the folded portion of the sheet material Bs is firmly pressed against the outer circumferential surface of the bead core Bc. When pressing the outer circumferential surface of the bead core Bc with the crimping roller 13b, it is preferable to bring the sheet material Bs covering the inner circumferential surface of the bead core Bc into contact with the bottom of the circumferential groove 8b, as illustrated in Figure 11. That is, it is preferable to press the sheet material Bs against the inner circumferential surface of the bead core Bc and the bottom of the circumferential groove 8b to firmly press the sheet material Bs against the inner circumferential surface of the bead core Bc. Note that with the other crimping rollers 13a and 13c, it is not necessary to bring the sheet material Bs covering the inner circumferential surface of the bead core Bc into contact with the bottom of the circumferential groove 8b.

[0044] Next, as illustrated in FIG. 12, the other end portion in the width direction of the sheet material Bs extending in the circumferential direction on the outer peripheral surface of the drum body 8 is folded back using the other folding guide 14b toward the bead core Bc in a state of being externally fitted in the circumferential groove 8b. Thereby, the folded portion of the sheet material Bs is pressure-bonded to the surface of the bead core Bc. More specifically, the folded portion of the sheet material Bs is overlapped with the sheet material Bs already pressure-bonded to the surface of the bead core Bc and pressure-bonded thereto.

[0045] Next, as illustrated in FIG. 13, the outer peripheral surface of the bead core Bc with both end portions in the width direction of the sheet material Bs folded back is pressed by the pressure-bonding roller 13c. Thereby, the portion where the sheet materials Bs overlap is securely pressure-bonded to the outer peripheral surface of the bead core Bc.

[0046] In this manner, the bead core Bc is sequentially placed in a state of being externally fitted in the circumferential groove 8b over the entire circumferential length, and the sheet material Bs is pressure-bonded to the surface of the bead core Bc, so that the surface of the bead core Bc is covered with the sheet material Bs over the entire circumferential length. When taking out the bead B manufactured in this way from the manufacturing apparatus 1, the pair of guide rollers 16a and 16b are integrally moved to the side of one guide roller 16a. Thereby, the outer peripheral surface of the bead B is pressed by the other guide roller 16b, making it easier to smoothly extract the bead B from the circumferential groove 8b.

[0047] As described above, according to the embodiment of this manufacturing apparatus 1, the sheet material Bs supplied to the outer peripheral surface of the drum body 8 is sandwiched between a circumferential portion of the bead core Bc in a state of being externally fitted in the circumferential groove 8b and the circumferential groove 8b, and is pressure-bonded to this circumferential portion. Therefore, regardless of the strength of the adhesiveness on the surface of the bead core Bc, the starting end portion of the sheet material Bs when covering the bead core Bc can be stably and firmly fixed to the surface of the bead core Bc. Therefore, during the process of covering the surface of the bead core Bc with the sheet material Bs, it is possible to avoid problems such as the sheet material Bs peeling off or shifting from the surface of the bead core Bc. Therefore, by sequentially externally fitting the bead core Bc into the circumferential groove 8b over the entire circumferential length, it is advantageous for productively manufacturing the bead B in which the surface of the bead core Bc is covered with the sheet material Bs over the entire circumferential length.

[0048] Therefore, this manufacturing apparatus 1 is particularly useful when the sheet material Bs cannot be firmly fixed to the surface of the bead core Bc due to the adhesiveness of the surface of the bead core Bc. That is, this manufacturing apparatus 1 is useful for covering the surface of the bead core Bc having a specification with weak surface adhesiveness or a specification composed only of a metal wire with the sheet material Bs.

[0049] In this embodiment, before bringing a circumferential portion of the bead core Bc into a state of being externally fitted in the circumferential groove 8b, the pushing jig 12 is used to bring the sheet material Bs into a state of being pushed into the circumferential groove 8b. Therefore, the central portion in the width direction of the sheet material Bs can be accurately guided and pushed into the circumferential groove 8b. As a result, the sheet material Bs can be extended in the circumferential direction with a desired width dimension on the outer peripheral surface of the drum body 8 on both sides of the circumferential groove 8b. That is, it becomes possible to control both end portions in the width direction of the sheet material Bs that are folded back toward the surface of the bead core Bc to a desired width dimension. As a result, both end portions in the width direction of the sheet material Bs can be folded back without excess or deficiency toward the surface of the bead core Bc by the folding guides 14a and 14b. Therefore, the quality of the manufactured bead B can be improved.

[0050] In this embodiment, perforations are formed across the sheet material Bs by the perforation unit 5 in the supply path that supplies the sheet material Bs to the outer circumferential surface of the drum body 8. When the sheet material Bs is pulled out and, for example, the perforations reach a predetermined position in the range corresponding to the area between the presser roller 11 and the crimping roller 13a, the sheet presser foot 10 is moved closer to the supply guide 9, and the sheet material Bs is sandwiched between the supply guide 9 and the sheet presser foot 10 to fix the pulled-out sheet material Bs (stopping the supply movement of the sheet material Bs). As a result, a large tension acts on the sheet material Bs, and the sheet material Bs is cut at the perforations.

[0051] In this way, when the perforation reaches a predetermined position on the outer surface of the drum body 8, the sheet material Bs is fixed at a position near the perforation upstream of the perforation, allowing the sheet material Bs to be cut to a predetermined length L by the perforation while the drum body 8 continues to rotate. As a result, the required predetermined length L of sheet material Bs can be obtained without stopping the rotation of the drum body 8 that is producing the bead B, which is increasingly advantageous for producing the bead B with high productivity.

[0052] Furthermore, the tip of the sheet material Bs cut at the perforations becomes the starting end of the sheet material Bs that will cover the next bead core Bc. When the sheet presser 10 is operated to cut the sheet material Bs at the perforations and at the same time perforations are made on the sheet material Bs by the perforation-making unit 5, the distance from the tip of the sheet material Bs cut at the perforations to the newly made perforations becomes the length (predetermined length L) of the sheet material Bs to be used next. If the specification of cutting the sheet material Bs to a predetermined length L is not adopted as in this embodiment, the sheet material Bs is cut to a predetermined length L by a known cutting means each time a sheet material Bs is to cover one bead core Bc and supplied to the outer surface of the drum body 8.

[0053] 1 Bead manufacturing apparatus 2 Supply reel 2a Support shaft 3 Drive roller 4 Festoon section 5 Perforation section 5a Blade section 5b Receiving section 6 Length adjustment mechanism 7 Direction changing roller 8 Drum body 8a Drum shaft 8b Circumferential groove 9 Supply guide 10 Sheet presser 11 Presser roller 12 Pressing jig 13 (13a, 13b, 13c) Crimping roller 14 (14a, 14b) Folding guide 15 Moving frame 16a, 16b Guide roller 17 Control unit B Bead Bc Bead core Bs Sheet material

Claims

1. In a method for manufacturing a bead, in which a sheet material is attached to the surface of an annular bead core and the surface is covered with the sheet material, a circumferential groove extending in the circumferential direction is formed on the outer surface of a drum body having a diameter smaller than the inner diameter of the bead core, the bead core is fitted onto the drum body, and a portion of the bead core in the circumferential direction is pressed toward the circumferential groove with a pressure roller and fitted into the circumferential groove, and the drum body is rotated around the drum axis to rotate the bead core so that the bead core is sequentially fitted into the circumferential groove along its entire circumferential length, A method for manufacturing a bead, wherein, when a portion of the bead core in the circumferential direction is fitted into the circumferential groove, the sheet material supplied to the outer circumferential surface is sandwiched between the portion in the circumferential direction and the circumferential groove and pressed against the portion in the circumferential direction, the sheet material is drawn out to a predetermined length along the circumferential groove by the rotating drum and the bead core, and both ends in the width direction that extend in the circumferential direction on the outer circumferential surface of the drawn sheet material are folded back toward the bead core that is fitted into the circumferential groove and pressed against the surface of the bead core, thereby covering the surface of the bead core with the sheet material over its entire circumferential length.

2. The method for manufacturing a bead according to claim 1, wherein the sheet material is pressed into the circumferential groove before the circumferential portion is fitted onto the circumferential groove.

3. A method for manufacturing a bead according to claim 1 or 2, wherein perforations are formed in the supply path for supplying the sheet material to the outer peripheral surface, and when the perforations reach a predetermined position on the outer peripheral surface, the sheet material is fixed at a position upstream of the perforations near the perforations, thereby cutting the sheet material to the predetermined length by the perforations while the drum body is rotating.

4. A bead manufacturing apparatus for manufacturing a bead whose surface is covered with a sheet material, comprising a pressing roller for pressing and attaching a sheet material to the surface of an annular bead core, the apparatus comprising: a drum body having a diameter smaller than the inner diameter of the bead core; a folding guide for folding back the sheet material; and a supply source for supplying the sheet material to the outer circumferential surface of the drum body, wherein a circumferential groove extending in the circumferential direction is formed on the outer circumferential surface, and a circumferential portion of the bead core, which is fitted onto the drum body, is pressed toward the circumferential groove by the pressing roller and fitted into the circumferential groove, and the drum body is rotated around the drum axis, thereby rotating the bead core, and the bead core is sequentially fitted into the circumferential groove along its entire circumferential length, A bead manufacturing apparatus wherein the sheet material supplied to the outer circumferential surface is sandwiched between a portion of the circumferential direction fitted into the circumferential groove and the circumferential groove, and is pressed against the portion of the circumferential direction, and the sheet material is drawn out to a predetermined length along the circumferential groove by the rotation of the drum body and the bead core, and both widthwise ends of the drawn-out sheet material that extend circumferentially on the outer circumferential surface are folded back by the folding guide toward the bead core fitted into the circumferential groove and pressed against the surface of the bead core, so that the surface of the bead core is covered with the sheet material over its entire circumferential length.

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