Method and apparatus for manufacturing beads

Abstract

The present invention provides a bead manufacturing method and apparatus that can efficiently produce beads with various specifications, in which the surface of the bead core is covered with a sheet material. [Solution] When a portion of the circumferential direction of the annular bead core Bc, which is fitted onto the drum body 8, is pressed by a pressure roller 13 toward a circumferential groove 8b formed on the outer surface of the drum body 8 and fitted into the circumferential groove 8b, a sheet material Bs is sandwiched between the circumferential portion of the bead core Bc and the circumferential groove 8b and the sheet material Bs is pressed onto this circumferential portion. By rotating the drum body 8 and the bead core Bc, the sheet material Bs is pulled out to a predetermined length along the circumferential groove 8b, and both widthwise ends of the sheet material Bs that extend circumferentially on the outer surface of the drum body 8 are folded back by folding guides 14a and 14b and pressed onto the surface of the bead core Bc, thereby covering the surface of the bead core Bc with the sheet material Bs over its entire circumferential length.

Description

Technical Field

[0001] The present invention relates to a method and apparatus for manufacturing beads, and more particularly, to a method and apparatus for manufacturing beads capable of producing beads having a bead core with various specifications and whose surfaces are covered with a sheet material with high productivity.

Background Art

[0002] Various methods are known for attaching and covering a sheet material to the surface of an annular bead core constituting a tire (see, for example, Patent Document 1). In the method proposed in Patent Document 1, starting from the position where the sheet material (tape) is attached to the inner peripheral surface of the bead core by a crimping 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, if its surface is covered with, for example, unvulcanized rubber, its surface has adhesiveness. 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 the case of 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 having surfaces covered with a sheet material with high productivity even for bead cores of various specifications.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] The object of the present invention is to provide a method and apparatus for manufacturing beads that can efficiently produce beads with various specifications, in which the surface of the bead core is covered with a sheet material. [Means for solving the problem]

[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. [Brief explanation of the drawing]

[0009] [Figure 1] This is an explanatory diagram illustrating an embodiment of a bead manufacturing apparatus in a side view. [Figure 2] Figure 1 is an explanatory diagram illustrating a bead manufacturing apparatus in a front view. [Figure 3] Figure 2 is an explanatory diagram illustrating the process of producing beads using the bead manufacturing apparatus shown. [Figure 4] This is an explanatory diagram illustrating the area around the press roller in Figure 3 from a top view. [Figure 5] This is an explanatory diagram illustrating the periphery of the outer surface of the drum body as seen from the perspective of arrow A in Figure 3. [Figure 6] Figure 3 is an explanatory diagram illustrating the area around the supply guide in a cross-sectional view. [Figure 7] This is an explanatory diagram illustrating the area around the pressing roller in Figure 3 in a cross-sectional view. [Figure 8] This is an explanatory diagram illustrating the area around the pressing jig shown in Figure 3 in a cross-sectional view. [Figure 9] This is an explanatory diagram illustrating a cross-sectional view of the area around the upper crimping roller in Figure 3. [Figure 10] This is an explanatory diagram illustrating the area around the upper folding guide in Figure 3 in a cross-sectional view. [Figure 11] This is an explanatory diagram illustrating a cross-sectional view of the area around the crimping roller in the middle of Figure 3. [Figure 12] This is an explanatory diagram illustrating the area around the lower folding guide in Figure 3 in a cross-sectional view. [Figure 13] This is an explanatory diagram illustrating a cross-sectional view of the area around the lower crimping roller in Figure 3. [Modes for carrying out the invention]

[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 FIGS. 1 to 5, a bead B in which the surface of an annular bead core Bc is covered with a sheet material Bs is manufactured. Since the bead B is a component of a tire, its specifications are determined according to tire performance, tire size, and the like.

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

[0013] This manufacturing apparatus 1 includes a drum body 8 having a smaller diameter than the inner diameter of the annular bead core Bc, a crimping roller 13 (13a, 13b, 13c) that crimps and attaches the sheet material Bs to the surface of the bead core Bc, a folding guide 14 (14a, 14b) that folds back the sheet material Bs, a supply reel 2 that serves as a supply source for supplying the sheet material Bs to the outer peripheral surface of the cylindrical drum body 8, and a control unit 17. The operations of various components of the manufacturing apparatus 1 are controlled by the control unit 17. A known computer is adopted for the control unit 17.

[0014] On the outer peripheral surface of the drum body 8 that rotates about the drum shaft 8a, a circumferential groove 8b extending over the entire circumferential length is formed. The supply path of the sheet material Bs is from the supply reel 2 to the drum body 8. A number of support rollers are arranged in this supply path, and the sheet material Bs is spanned over these support rollers. Arrows X and Y in the figure indicate the front-rear direction and the width direction of the manufacturing apparatus 1, respectively. The X direction and the Y direction are perpendicular to each other. Also, the dashed-dotted line CL indicates the center in the width direction of the drum body 8, and the dashed-dotted line Z indicates the axis of the drum shaft 8a of the drum body 8. Note that 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 around the supply reel 2 about a support shaft 2a extending in the Y direction. On the downstream side in the supply direction of the sheet material Bs with respect to the supply reel 2, a drive roller 3, a festoon section 4, a perforation imparting section 5, a length adjustment mechanism 6, and a direction changing roller 7 are arranged in this order. The downstream side of the direction changing roller 7 in the supply path will be described later.

[0016] The direction of the supply path is changed by 90° in plan view by the direction changing roller 7. Therefore, the support shaft 2a (axis) of the supply reel 2 and the drum shaft 8a (axis) of the drum body 8 are orthogonal to each other in plan view. If the support shaft 2a (axis) of the supply reel 2 and the drum shaft 8a (axis) of the drum body 8 are made parallel, the space required for installing the manufacturing apparatus 1 will become excessive. Therefore, by using the direction changing roller 7 to change the direction of the supply path by 90° midway, the manufacturing apparatus 1 is made compact.

[0017] The drive roller 3 rotationally driven by an electric motor or the like rotates the supply reel 2 about the support shaft 2a to feed out the sheet material Bs from the supply reel 2. The sheet material Bs fed out from the supply reel 2 in this way is supplied toward the outer peripheral surface of the drum body 8 by the rotation of the drum body 8. The festoon section 4 has support rollers arranged vertically apart from each other, and by draping the sheet material Bs over these support rollers, an extra length of the sheet material Bs is secured, and it functions to apply an appropriate constant tension to the draped sheet material Bs.

[0018] [[ID=I1]] The perforation imparting section 5 has a blade portion 5a and a receiving portion 5b, and the blade portion 5a moves closer to and away from the receiving portion 5b. When the blade portion 5a moves closer to the receiving portion 5b, a perforation crossing in the width direction is imparted to the sheet material Bs passing between the blade portion 5a and the receiving portion 5b. Various known specifications can be adopted for the perforation imparting section 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 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 toward and away from the supply guide 9. When the sheet retainer 10 moves toward 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 periphery 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 along 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 back both ends in the width direction of the sheet material Bs 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 extrapolated 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 extrapolated 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 to 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 towards the circumferential groove 8b by the pushing 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 for stably pressing the sheet material Bs onto 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 securely 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 Figure 12, the other end in the width direction 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 the other folding guide 14b. This presses the folded portion of the sheet material Bs against the surface of the bead core Bc. More specifically, the folded portion of the sheet material Bs is overlapped and pressed against the sheet material Bs that is already pressed against the surface of the bead core Bc.

[0045] Next, as illustrated in Figure 13, the outer surface of the bead core Bc, where both widthwise ends of the sheet material Bs are folded back, is pressed by the compression roller 13c. This ensures that the overlapping portions of the sheet material Bs are securely pressed against the outer surface of the bead core Bc.

[0046] In this way, the bead core Bc is sequentially fitted into the circumferential groove 8b along its entire circumferential length, and the sheet material Bs is pressed onto the surface of the bead core Bc, thereby covering the surface of the bead core Bc with the sheet material Bs along its entire circumferential length. When removing the bead B manufactured in this way from the manufacturing apparatus 1, the pair of guide rollers 16a and 16b are moved together towards one of the guide rollers 16a. As a result, the outer circumferential surface of the bead B is pressed by the other guide roller 16b, making it easier to smoothly remove the bead B from the circumferential groove 8b.

[0047] As described above, according to this embodiment of the manufacturing apparatus 1, the sheet material Bs supplied to the outer circumferential surface of the drum body 8 is sandwiched between a portion of the bead core Bc, which is fitted into the circumferential groove 8b, and the circumferential groove 8b, and is pressed against this portion of the bead core. Therefore, regardless of the adhesive strength of the surface of the bead core Bc, the starting end 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, problems such as the sheet material Bs peeling off or shifting from the surface of the bead core Bc during the process of covering the surface of the bead core Bc with the sheet material Bs can be avoided. Thus, by sequentially fitting the bead core Bc into the circumferential groove 8b along its entire circumferential length, it is advantageous to efficiently manufacture beads B in which the surface of the bead core Bc is covered with sheet material Bs along its 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. In other words, this manufacturing apparatus 1 is useful for coating the surface of a bead core Bc with sheet material Bs, especially when the surface has weak adhesiveness or when it is composed only of metal wires.

[0049] In this embodiment, before fitting a portion of the bead core Bc into the circumferential groove 8b, the sheet material Bs is pressed into the circumferential groove 8b using the pressing jig 12. This allows the widthwise center of the sheet material Bs to be accurately guided and pressed into the circumferential groove 8b. As a result, the sheet material Bs can be extended circumferentially with a desired width on the outer circumferential surfaces of the drum body 8 on both sides of the circumferential groove 8b. That is, it becomes possible to control the widthwise ends of the sheet material Bs that fold back toward the surface of the bead core Bc to a desired width. As a result, the folding guides 14a and 14b allow the widthwise ends of the sheet material Bs to be folded back toward the surface of the bead core Bc without excess or deficiency. 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 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. This makes it possible to obtain the required predetermined length L of sheet material Bs 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 length of the sheet material Bs to be used next becomes the length (predetermined length L) from the tip of the sheet material Bs cut at the perforations to the newly made perforations. 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. [Explanation of Symbols]

[0053] 1. Bead manufacturing equipment 2 supply reels 2a spindle 3 Drive rollers 4 Festoon Club 5. Perforation section 5a Blade 5b Receiving part 6. Length adjustment mechanism 7 Directional changing rollers 8 drum bodies 8a Drum shaft 8b Circumferential groove 9. Supply Guide 10 Sheet holder 11 Pressing roller 12 Pressing jig 13 (13a, 13b, 13c) Crimping roller 14 (14a, 14b) Folding Guide 15 Movement Frames 16a, 16b Guide rollers 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 the drum body, which has 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 by a pressure roller so that it is fitted into the circumferential groove. By rotating the drum body around the drum axis, the bead core is rotated 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 across the sheet material in the supply path for supplying the sheet material to the outer circumferential surface, and when the perforations reach a predetermined position on the outer circumferential 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 having a pressure roller for pressing and attaching a sheet material to the surface of an annular bead core, wherein the surface of the bead is covered with the sheet material, The device comprises 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 surface of the drum body. The outer surface has circumferential grooves extending in the circumferential direction, A portion of the bead core, which is fitted onto the drum body, is pressed toward the circumferential groove by the crimping roller and fitted into the circumferential groove. By rotating the drum body around the drum axis, the bead core rotates, and the bead core is sequentially fitted into the circumferential groove along its entire circumferential length. 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 pulled out along the circumferential groove to a predetermined length by the rotation of the drum body and the bead core, A bead manufacturing apparatus in which both widthwise ends of the drawn-out sheet material, which extend circumferentially on the outer peripheral surface, are folded back by the folding guide toward the bead core which is 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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