JP3425090B2 - Tire manufacturing method - Google Patents

Description

BACKGROUND OF THE INVENTION [0001] [Technical Field of the Invention The present invention relates to the production how the tire can reduce the radial run-out. 2. Description of the Related Art When manufacturing a tire, for example, a typical pneumatic radial tire, first, a band-shaped carcass ply is wound around a former having a perfect circular cross section, and both circumferential ends thereof are overlapped in a radial direction. A joint (overlap joint) is formed to form a cylindrical carcass ply. Further, annular bead cores are extrapolated at both ends in the axial direction of the cylindrical carcass ply, and the both ends of the carcass ply are wound up. Further, a sidewall rubber or the like is attached on the carcass ply. [0003] Thereafter, the carcass ply is deformed in a toroidal shape while narrowing the axial distance between the pair of bead cores, thereby forming a raw tire main portion. The toroidal green tire main portion is provided with a ring-shaped green tread portion on its outer periphery to form a green cover, which is vulcanized by a mold to manufacture a tire. [0004] By the way, the carcass ply, the side wall rubber and the like described above are jointed at both ends in the circumferential direction on the former, but the joint portion is thicker than other portions. And the radial runout (hereinafter, sometimes simply referred to as “RRO”), which is the vertical run-out of the tire in the radial direction, is likely to be increased. [0005] If the RRO is large, the roundness of the tire is impaired, which causes an abnormal force such as radial force variation when the tire is rotated. In order to solve such a problem, it has been proposed to dispose the above-mentioned joint portions in a tire circumferential direction, but a sufficient effect has not yet been obtained. According to the results of various experiments conducted by the inventors, the RRO of the already vulcanized tire and the RRO of the raw tire main body before vulcanization molding or the green cover having a green tread portion arranged thereon are shown.
It was found that there was a certain correlation with RO. In particular, regarding the RRO of the raw tire main part or the raw cover, the main cause is that the code path of the carcass ply is variously different, and in the case of a tire molded using the same former, a very similar RRO is obtained. Was found to be present.
The inventors have examined the RRO of the main part of the raw tire in advance,
By positively changing the code path so as to reduce the RRO, the inventors have found that the RRO can be reduced and a tire having a high roundness can be obtained, and the present invention has been completed. [0007] As described above, the present invention provides a method for producing a vulcanized tire having an R
It is an object of the present invention to provide a method for manufacturing a tire capable of reducing RO. [0008] The invention according to claim 1 (the present invention) provides a ring in which a toroidal raw tire main portion is formed by a foamer, and the raw tire main portion and its outer periphery are arranged. A vulcanized tire is formed by vulcanizing a green cover having a green tread portion in the form of a vulcanized tire, wherein the former is arranged side by side in a circumferential direction and is capable of moving forward and backward in a radial direction. Having a number of segments, forming a reference outer peripheral surface that forms a perfect circle by equalizing the radial distance of the outer peripheral surface of the segment, and an inner liner, a carcass ply, and a sidewall rubber that form the main portion of the raw tire When each circumferential joint is positioned on a specific segment of the former and wound, and the circumferential position of the vulcanized tire is vulcanized to correspond to the segment. Both, measuring the radial runout of the raw tire main part, raw cover or vulcanized tire, based on the measurement results of this radial runout, projecting the segment corresponding to the concave portion of the radial runout outside the reference outer peripheral surface, Further, after the segment corresponding to the convex portion of the radial runout is deformed into a modified outer peripheral surface depressed inward from the reference outer peripheral surface , the next raw tire main portion is formed . An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a vulcanized tire T (shown in FIG. 2) is obtained by vulcanizing a green cover 4 having a toroidal green tire main portion 2 and a ring-shaped green tread portion 3 arranged on the outer periphery thereof. It is formed. The raw cover 4 and the vulcanized tire T are manufactured sequentially and continuously. The raw tire main part 2 is formed by a former F for forming a tire main part. As shown in FIG. 3, the former F has a plurality of segments S which are arranged side by side in the circumferential direction and are capable of moving back and forth in the radial direction. In this example, the segment S uses eight pieces having an outer peripheral surface having the same circumferential length, but the number of divisions and the like can be changed as appropriate, and the circumferential length can be changed as appropriate. In this example, the length S (shown in FIG. 6) of the segment S in the axial direction is set to be equal. In the present embodiment, each of the segments S is supported via a segment advance / retreat means 10 so as to extend radially from a support shaft 9 located at the center. As the segment advance / retreat means 10, an appropriate means such as a hydraulic cylinder or a combination of a hydraulic cylinder and a link mechanism is used. Then, the former F is operated by the segment advance / retreat means 10.
By making the radial distance Rd from the center of the support shaft 9 to the outer peripheral surface 6 of each segment S uniform, the reference outer peripheral surface 5 that forms a perfect circle can be formed. Further, in the former F of this embodiment, as shown in FIG. 4, for example, irregularities can be formed on the outer peripheral surface by changing the radial distance to the outer peripheral surface 6 of the segment S. More specifically, the outer peripheral surface 6 of the segment S
Radially inward of the reference outer peripheral surface 5 (segment S
1) and radially outward (see segment S2). By adjusting the stroke amount of the segment advance / retreat means 10, each of the segments S is arranged at each of the positions so as to be freely aligned. Each of the segments S has an inclined surface C whose circumferential edge is away from an adjacent segment so that the segments S do not collide with each other when moving forward and backward. Next, a method for forming the green tire main portion 2 using the former F will be described. First, in this example, the outer peripheral surface of the former F is a reference outer peripheral surface 5 that is a perfect circle.
(Fig. 3). In this example, as shown in FIG. 5, an air-impermeable inner liner 12 is first wound on the reference outer peripheral surface 5 of the former F, and a carcass ply 13 is wound thereon. The carcass ply 13 is formed by covering both sides of a cord arrangement body arranged in parallel with a thin topping rubber, and the cords of the ply are parallel or at a small angle to the axial direction of the former F. It is wound around the outer peripheral surface of the former F to form a cylindrical carcass ply. Next, as shown in FIG.
For example, bead apex rubber 1
The annular bead core 15 connected to 6 is extrapolated, and both ends of the carcass ply 13 are wound up. At this time, the code path of the carcass ply 13 has a length along the segment S from one bead core 15 to the other bead core 15. After that, the first cover is formed by winding the side wall rubber 14 (1st molding).
The former is reduced in diameter and the cover is taken out. The circumferential ends of the inner liner 12, the carcass ply 13, and the sidewall rubber 14 are joined in a radially overlapping manner as shown in FIG. Note Each joint position 12j, 13j, 14j, etc. becomes a particular location on the pre-former, in this case, each segment S
It is wound so as to be on P1, SP2 and SP3.
That is, the inner liner 12 and the car
The circumferential direction of the casply 13 and the sidewall rubber 14
Each joint position 12j, 13j, 14j
F is positioned and wound on a particular segment S of F. Next, a bead portion is mounted (locked) on a clamp ring of a second molding machine (not shown) and expanded and deformed while reducing the axial distance between the pair of bead cores 15 of the first cover, as shown in FIG. The toroidal raw tire main part 2 is formed. Next, the outer peripheral portion 2a of the raw tire main portion 2
Then, the green cover 4 is molded (2nd molding) by bonding the green tread portion 3 to the green tread portion 3 and then vulcanized in a mold to manufacture the tire T. The raw tread portion 3 is formed by previously integrating a belt reinforcing layer 3b including a belt layer and the like, a tread rubber 3a, and the like. Further, the raw tread portion 3 may be formed in a ring shape in advance, and may be joined together with the expansion of the first cover. Then, such a raw tire main part 2,
Radial runout of raw cover 4 or vulcanized tire T
For example, it is measured by a non-contact type sensor or the like. In this example, FIG. 7 shows a waveform obtained by measuring the RRO of the vulcanized tire. The vertical axis is RRO (the amount of run-out in the tire radial direction), where a negative value indicates a concave in the tire radial direction and a positive value indicates a convex in the tire radial direction, and the horizontal axis indicates the reference position. (0-360 °). Next, in the present embodiment, the R
Based on the RO of the measurement result, the outer peripheral surface of the former F for the main portion formed partially moved back and forth in the radial direction, Ru reduce the RRO of the vulcanized tire. FIG. 8 shows an example of the RRO of the former in which the outer peripheral surface is partially moved in the radial direction as described above, together with the measurement result of the RRO of the vulcanized tire. In the figure, when the former forms the reference outer peripheral surface 5, R
RO becomes 0. In addition, the phase matches the phase from the reference position in the vulcanized tire. Therefore, raw cover 4
By performing vulcanization molding in such a manner that a specific position in the circumferential direction of the vulcanizing die is matched with a specific position in the vulcanizing mold, it is possible to determine which segment S of the former F corresponds to any position in the circumferential direction of the vulcanized tire T. You can know. Thus, vulcanized tires
Vulcanization molding corresponding to the segment in the circumferential direction of the segment
Is done. As means for reducing the RRO of a vulcanized tire,
Some segments S corresponding to the concave portions A of the RRO of the tire of the former F are projected outside the reference outer peripheral surface 5, and some segments S corresponding to the convex portions B of the RRO are connected to the reference outer peripheral surface 5. The modified outer peripheral surface depressed inward from the surface 5 is illustrated as an example. As described above, when the next raw tire main portion 2 is formed by using the former F for forming the raw tire main portion as the modified outer peripheral surface as described above, the outer peripheral surface of the segment S is located outside the reference outer peripheral surface 5. , The code path becomes longer by that amount. Therefore, for example, this part of the raw tire main part 2 is made convex in the tire radial direction as compared with the part of the reference outer peripheral surface 5, and it is possible to prevent the RRO from becoming concave. Similarly, at a position where the outer peripheral surface of the segment S of the former F is recessed inward from the reference outer peripheral surface 5,
The code path is shortened by the amount of the depression. Therefore, the portion of the raw tire main portion 2 corresponding to this segment S is concave in the tire radial direction as compared with the portion of the reference outer peripheral surface 5,
RRO can be prevented from becoming convex. [0025] Thus, the raw tire main portion formed into already 2, measures the RRO raw cover 4 or vulcanization tire T, the feedback element to reduce the RRO of the raw tire main portion which is then shaping the data , It is possible to gradually reduce the RRO of a continuously manufactured tire, and by repeating such feedback, the RRO is further reduced, and a tire having a high roundness can be obtained. . The procedure of such a process is shown in FIG. The former F having the modified outer peripheral surface described above
As shown in FIG. 9, it was found that the tire T was significantly reduced as shown in FIG. The amount of protrusion and dent of the former F from the reference outer peripheral surface 5 is preferably, for example, within the range of about ± 2.0 mm, and the amount of protrusion and dent is determined for each segment. It goes without saying that various settings can be made. As described above, one embodiment of the present invention has been described in detail. However, when the first molding and the second molding are performed in parallel, the green tire main part 2 or 1 obtained by the first molding or the second molding is obtained. The RRO may be measured for each of the raw covers 4, and each time, the outer peripheral surface of the former F may be made uneven in the first molding. This case is preferable because the RRO correction feedback is reflected early. Further, the average value of RRO may be calculated for each production lot and reflected on the next production lot, and these methods may be arbitrarily determined. Further, in this example, the RRO of the vulcanized tire T is measured for feedback, but the same effect can be obtained by measuring the RRO of the raw tire main part 2 or the raw cover 4. EXAMPLES The present invention was applied to manufacture a pneumatic radial tire having a tire size of 275 / 70R16. First, a green tire main part and a green cover were molded using a former having a perfect circular reference outer peripheral surface, and a vulcanized tire (comparative example) was prototyped. When the RRO of this vulcanized tire was measured,
The waveform of FIG. 7 is obtained, and the RRO of the overall value is 0.
Although the outer peripheral surface of the former was 93 mm, a green tire main part and a green cover were formed with the outer peripheral surface of the former being the modified outer peripheral surface shown in FIG. 8, and a vulcanized tire (example) was prototyped.
And it was confirmed that the overall value was reduced to 0.37 mm. [0031] [Effect of the Invention] As described above, in the present invention, Ru can reduce the RRO of the vulcanized tire.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view illustrating a raw tire main portion and a raw cover. FIG. 2 is a cross-sectional view of a vulcanized tire. FIG. 3 is a cross-sectional view of a former, showing a reference outer peripheral surface. FIG. 4 is a cross-sectional view of the former, showing a non-reference outer peripheral surface. FIG. 5 is a cross-sectional view of the former during a tire building process. FIG. 6 is a partial cross-sectional view along an axial direction of a former during a tire forming process. FIG. 7 is a waveform diagram showing a measurement result of RRO of a vulcanized tire. FIG. 8 is a waveform chart showing measurement results of a former. FIG. 9 is a waveform chart showing a measurement result of RRO of a vulcanized tire. FIG. 10 is a conceptual diagram showing the steps of the present invention. [Description of Signs] 2 Raw tire main part 3 Raw tread part 4 Raw cover F Former S segment

Claims (1)

(57) [Claims 1] A raw cover having a toroidal green tire main portion formed by a foamer and having the green tire main portion and a ring-shaped green tread portion disposed on the outer periphery thereof. Vulcanizing a vulcanized tire to form a vulcanized tire, wherein the former has a plurality of segments arranged side by side in the circumferential direction and capable of moving back and forth in the radial direction, By forming a reference outer peripheral surface that forms a perfect circle by equalizing the radial distance of the outer peripheral surface, the inner liner, carcass ply, and peripheral rubber joints that constitute the main part of the raw tire are identified by a former. Wound on the segment of
And while vulcanizing the circumferential position of the vulcanized tire in correspondence with the segment, measuring the radial runout of the raw tire main part, green cover or vulcanized tire, based on the measurement results of this radial runout, the segments corresponding to the recesses of the radial run-out is protruded outward from the reference outer peripheral surface, and after the segment corresponding to the convex portion of the radial run-out is deformed to fix the outer peripheral surface is recessed inward from said reference outer peripheral surface And a method for manufacturing a tire, comprising forming the following main part of a raw tire .