JP4388329B2 - Raw tire manufacturing method - Google Patents

Description

  The present invention relates to a green tire manufacturing method for improving the appearance performance and uniformity of a tire.

  In the manufacturing process of the raw tire (tire before vulcanization) in the radial tire, in order to arrange the carcass cords in a radial manner, as shown in FIG. 4, a tire winding body B including a carcass ply A1 once formed in a cylindrical shape, A process (inflation process) is performed in which the bead cores C and C are expanded in a toroidal shape, and the expanded portion Bc is adhered to the tread ring T that has been kept on standby in advance. In this inflation process, it is important for the appearance performance and uniformity of the so-called bulge dent and the like that the tire winding body B is uniformly expanded to make the circumferential arrangement of the carcass cords uniform.

  However, since the tire winding body B is a laminated body in which a plurality of rubber materials including the carcass ply A1 are laminated, it is difficult to inflate uniformly over the entire circumference. For example, as shown in FIG. There is a problem in that the circumferential arrangement of the carcass cord a varies, such as a rough portion y1 / a dense portion y2, and the appearance performance and uniformity of the finished tire are impaired. In particular. As shown in FIG. 5B, the joint portion J where the circumferential end portions of the carcass ply A1 overlap each other has a large thickness and rigidity, so that expansion is suppressed. Therefore, in the adjacent portions R and R adjacent to the joint portion J, The expansion of the region becomes excessive compared with other regions, and the difference in density, that is, the variation in the circumferential arrangement is made larger.

  Therefore, the present invention provides a carcass cord in a tire winding body based on preheating and heating the tire winding body to a uniform temperature in the range of 30 to 50 ° C. in advance using a high-temperature working gas in the inflation process. It becomes easy to extend the rubber between and it is possible to reduce the difference in extension over the entire circumferential direction, it is possible to improve the uniformity of expansion of the tire winding body, suppress variation in the circumferential arrangement of the carcass cord, It aims at providing the manufacturing method of the raw tire which can improve the external appearance performance and uniformity in a finished tire.

JP 2002-103472 A

In order to achieve the above object, the invention of claim 1 of the present application is a winding in which a primary tire member including a carcass ply is wound around an outer peripheral surface of a cylindrical former to form a right cylindrical tire winding body. Body formation process,
A bead core setting step of inserting the bead core from both outer ends in the axial direction of the tire wound body and setting the bead core on the radially outer side of the wound body;
A ring setting step of disposing a tread ring made of at least a belt ply and a tread rubber, concentrically with the tire winding body and at a distance radially outward;
Including an inflation step of sticking the tread ring and the center portion of the inflated tire roll by inflating the tire roll in a toroidal shape between bead cores,
In the inflation step, the tire winding body is formed using a high-temperature and low-pressure pre-operating gas having a temperature T1 of 50 to 100 ° C. and a pressure P1 of 5 to 50 kPa inside the tire winding body and at least between the bead cores. A preheating step for preheating to a uniform temperature in the range of 30 to 50 ° C ;
After the preheating step, the inflation gas is allowed to expand by using the working gas at a high temperature and a high pressure at which the temperature T2 is in the same range as the temperature T1 and the pressure P2 is increased to 100 to 250 kPa. It is characterized by including .

The invention of claim 2 is characterized in that the pressure P2 is in a range of 140 to 180 kPa .

  In the inventions of claims 3 and 4, the working gas is characterized in that the temperature T2 is the same temperature as the temperature T1 or higher or lower than the temperature T1.

  According to a fifth aspect of the present invention, the working gas is air and / or an inert gas.

  Since the present invention is configured as described above, it becomes possible to improve the uniformity of expansion of the tire winding body in the inflation process, suppress the variation in the circumferential arrangement of the carcass cords, and the appearance performance in the finished tire And the uniformity can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The manufacturing method of the green tire of the present invention is as follows:
<1> A wound body forming step S1 in which a primary tire member A including a carcass ply A1 is wound around an outer peripheral surface of a cylindrical former F1 to form a straight cylindrical tire wound body B (FIG. 1A). )When,
<2> Bead core setting step S2 in which bead cores C are inserted from both outer ends in the axial direction of the tire wound body B, and the bead cores C are set on the radially outer side of the tire wound body B (FIG. 1B). When,
<3> A ring setting step S3 (FIG. 2) in which a tread ring T is arranged concentrically with the tire winding body B and spaced radially outward.
<4> Inflation step S4 for sticking the tread ring T to the center portion Bc of the expanding tire roll B by inflating the tire roll B between the bead cores C and C in a toroidal shape. (FIGS. 3A and 3B).

  In the present invention, in the inflation step S4, the high temperature working gas X is fed into the tire winding body B and at least between the bead cores C and C, so that the tire winding body B is 30 to 50 ° C. In this range, the tire winding body B is inflated into a toroidal shape using the working gas X, and then adhered to the tread ring T.

  Here, in this example, the case where the manufacturing method of the green tire is adopted in a so-called two-stage forming method is illustrated, and subsequently the both ends of the tire wound body B after the bead core setting step S2. A folding step S5 (FIG. 1 (C)) for folding back Be around the bead core C is performed. The cylindrical folded tire winding body BT thus obtained is removed from the former F1 and transferred to the shaping former F2 shown in FIG. 2, and then the ring setting step S3 and the inflation step S4 are performed.

  The primary tire member A constituting the tire winding body B is usually configured to include the carcass ply A1 and an inner liner rubber sheet (not shown) disposed radially inward thereof. Accordingly, bead rubber (so-called clinch rubber or the like) forming the outer skin of the bead portion and / or side wall rubber or the like forming the outer skin of the sidewall portion can be added to the primary tire member A.

  The tread ring T includes a belt layer T1 composed of a plurality (usually two) of belt plies and a tread rubber T2 arranged on the outer side in the radial direction. Can be added. The tread ring T is integrally formed in an annular shape by a separate process using a belt drum.

  Further, in the raw tire manufacturing method of the present invention, only the inflation step S4 is different from the conventional one, and other winding body forming step S1, bead core setting step S2, ring setting step S3, folding step S5, etc. It can be carried out by the same method as in the prior art.

  Therefore, only this inflation step S4 will be described in detail below. As shown in FIGS. 2 and 3A, the tire winding body BT is held below the bead core C by the clamp ring 10 of the shaping former F2.

The inflation step S4 is performed as shown in FIGS. 3 (A) and 3 (B).
(1) temperature T1 is 50 to 100 ° C., and the preliminary working gas X1 hot low pressure P1 is 5～50KP a, and air from the sheet discharge port 11 provided on the clamp ring 10, the tire wound body B A preheating step S4a for heating to a uniform temperature T0 within a range of 30 to 50 ° C .;
(2) By supplying the high-temperature and high-pressure main working gas X2 in which the temperature T2 is in the same range as the temperature T1 and the pressure P2 is raised to 100 to 250 kPa, the tire winding body B is expanded in a toroidal shape, It includes an inflation step S4b for adhering the central portion Bc of the inflated tire roll B and the tread ring T.

  Here, the elongation of the unvulcanized rubber changes depending on the difference in temperature and the thickness of the rubber. Therefore, the conventional inflation process is greatly affected by changes in environmental temperature, changes in material temperature, and the like, and variations in the circumferential arrangement of carcass cords are likely to occur. In particular, as in the case of a conventional inflation process, when the temperature of the rubber is as low as 25 ° C. or less, for example, the flexibility of the rubber is significantly reduced and the overall expansion becomes difficult. Even when the difference is small, the elongation tends to concentrate on the easily stretchable portion, and the variation in the circumferential arrangement becomes larger.

  In contrast, in the preheating step S4a, the tire winding body B is preheated to a uniform temperature T0 in the range of 30 to 50 ° C. Therefore, influences such as changes in environmental temperature and changes in material temperature can be eliminated. In addition, since the rubber of the tire wound body B can be softened moderately and its extensibility can be increased uniformly, even when there is a difference in thickness such as a joint part, for example, a part other than the joint part (for example, the joint part and It is possible to alleviate the concentration of elongation in the adjacent portion), and in combination with the elimination of the influence of the temperature change, the variation in the circumferential arrangement can be effectively suppressed.

  If the uniform temperature T0 is less than 30 ° C., the flexibility and extensibility of the rubber are insufficient, and the effect of suppressing the variation in the circumferential arrangement cannot be sufficiently exhibited. On the contrary, when the uniform temperature T0 exceeds 50 ° C., it becomes too soft and it becomes difficult to support the internal pressure P2 in the next inflation step S4b. For example, the rubber between the carcass cords is deformed radially outward or New problems such as tearing occur. Therefore, the uniform temperature T0 is preferably in the range of 30 to 50 ° C.

  The “uniform temperature T0” is the maximum value T0max when the temperatures at least at four positions in the circumferential direction on the tire equator are measured on both the inner peripheral surface side and the outer peripheral surface side of the tire winding body B. And the minimum value T0min (T0max−T0min) means 5% or less of the minimum value T0min.

  In the preheating step S4a, it is necessary to fill the preliminary working gas X1 at the reference position P1 of the clamp ring 10 where the tire winding body BT is held in a right cylindrical shape. That is, when the clamp ring 10 is moved inward in the tire axial direction from the reference position P1, the tire winding body BT swells in a drum shape also by the preliminary working gas X1, and in this preheating step S4a, This is because there is a possibility that the circumferential arrangement of the carcass cords may already vary.

The pressure P1 of the preliminary working gas X1 is, it is also important in the range and the low pressure of the 5～50KP a, exceeds 50KP a, rubber extending or distortion between the carcass cords occurs, subsequent circumferential This will adversely affect the orientation. If the pressure P1 is less than 5 kPa and the temperature T1 is less than 50 ° C., the heating effect is inferior, for example, the amount of heat of the preliminary working gas X1 is insufficient, and it takes a long time to preheat the tire winding body B to the temperature T0. It will be necessary. On the other hand, when the temperature T1 exceeds 100 ° C., it is difficult to control the temperature T0 of the tire winding body B within the above range, and there is a possibility of causing burns on the inner peripheral surface side of the tire winding body B. Therefore, it is more preferable that the preparatory working gas X1 has a pressure P1 of 5 to 25 kPa, and a temperature T1 of 50 to 70 ° C. is more preferable. When T1 is 50 to 100 ° C., the heating time is usually about 10 to 60 seconds.

  Next, in the inflation step S4b, as shown in FIG. 3B, the high-temperature and high-pressure main working gas X2 in which the temperature T2 is in the same range (50 to 100 ° C.) as the temperature T1 and the pressure P2 is 100 to 250 kPa. The tire winding body B is expanded between the bead cores C and C in a toroidal shape. At this time, the temperature T2 of the working gas X2 can be the same temperature as the temperature T1, or higher or lower than the temperature T1, but from the viewpoint of suppressing variation in the circumferential arrangement, the temperature T2 is Most preferably, the temperature is the same as the temperature T1, and then it is preferably higher than the temperature T1. The temperature difference between temperatures T2 and T1 is preferably 10 ° C. or less.

  If the pressure P2 is less than 100 kPa, it is difficult to sufficiently inflate the tire winding body B. If the pressure P2 exceeds 250 kPa, the rubber between the carcass cords is deformed radially outward or broken. Is generated. Therefore, the pressure P2 is more preferably in the range of 140 to 180 kPa.

  In the preliminary working gas X1 and the main working gas X2, one or more kinds of gases selected from inert gases such as nitrogen and argon, or air, or a mixed gas of air and the inert gas is used. be able to.

  The secondary tire members other than the primary tire member A are attached to the tire winding body B prior to the inflation step S4 and / or the tire winding body B and the tread ring after the inflation step S4. It can be attached to a sticking body with T.

  In the case of the so-called single stage forming method, the steps S1 to S4 are sequentially performed on one single molding former (not shown) without transferring the tire winding body B (or BR). At this time, the folding step S5 is usually performed between the bead core setting step S2 and the inflation step S4, simultaneously with the inflation step S4b of the inflation step S4, or after the inflation step S4b.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  Based on the production method of the present invention, raw tires were manufactured according to the specifications shown in Table 1, each raw tire was vulcanized, and the uniformity of the finished tire (tire size 195 / 65R15) was measured. The comparative example and the example differ only in the inflation step.

(1) Uniformity:
Using Uniformity Tester, LRO (Lateral Run Out), RFV (Radial Force Variation), RFV Primary (Radial Force Variation Primary), LFV (Lateral Force Variation), CON (Conicity) ) Were measured, and the average value and standard deviation were compared.

  As shown in the table, it can be confirmed that in the examples, the LRO, the RFV, and the RFV primary were greatly improved.

(A)-(C) is a diagram explaining a wound body formation process, a bead core setting process, and a return process. It is a diagram explaining a ring set process. (A), (B) is a diagram explaining an inflation process. It is a diagram explaining a prior art. (A) and (B) are diagrams showing the problems.

Explanation of symbols

A1 Carcass ply A Primary tire member B Tire winding body C Bead core F1 Former S1 Winding body forming step S2 Bead core setting step S3 Ring setting step S4 Inflation step S4a Preheating step S4b Inflation step T Tread ring T0 Uniform temperature X Working gas X1 preliminary working gas X2 working gas

Claims (5)

A wound body forming step in which a primary tire member including a carcass ply is wound around an outer peripheral surface of a cylindrical former to form a straight cylindrical tire wound body;
A bead core setting step of inserting the bead core from both outer ends in the axial direction of the tire wound body and setting the bead core on the radially outer side of the wound body;
A ring setting step of disposing a tread ring made of at least a belt ply and a tread rubber, concentrically with the tire winding body and at a distance radially outward;
An inflation step of sticking the tread ring and the central portion of the expanding tire winding body by inflating the tire winding body in a toroidal shape between bead cores,
In the inflation step, the tire winding body is formed using a high-temperature and low-pressure pre-operating gas having a temperature T1 of 50 to 100 ° C. and a pressure P1 of 5 to 50 kPa inside the tire winding body and at least between the bead cores. A preheating step for preheating to a uniform temperature in the range of 30 to 50 ° C ;
After the preheating step, the inflation gas is allowed to expand by using the working gas at a high temperature and a high pressure at which the temperature T2 is in the same range as the temperature T1 and the pressure P2 is increased to 100 to 250 kPa. A method for producing a raw tire, comprising: The method for producing a raw tire according to claim 1, wherein the pressure P2 is in a range of 140 to 180 kPa . The present working gas, the raw tire manufacturing method according to claim 1, wherein the temperature T2 is the same temperature as the temperature T1. The present working gas, the raw tire manufacturing method according to claim 1, wherein the temperature T2 is higher or lower temperature than the temperature T1.   The said working gas consists of air and / or an inert gas, The manufacturing method of the raw tire in any one of Claims 1-4 characterized by the above-mentioned.

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