JP5452123B2 - Pneumatic tire manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire having a rubber member formed by bonding two types of rubber layers formed by a so-called strip wind method, and more specifically, suppressing the occurrence of vulcanization defects such as bears in the rubber member. The present invention relates to a method for manufacturing a pneumatic tire.

  In recent years, as shown in FIG. 6A, an unvulcanized rubber strip s in the form of a ribbon is placed on a cylindrical forming drum d from one side in the axial direction so that the side edges thereof overlap each other. A so-called strip wind method is employed in which a rubber member e for a tire such as a sidewall rubber or an inner liner rubber is formed by being spirally wound on the side (see, for example, Patent Documents 1 and 2 below). The rubber member e in FIG. 6 (a) is a second rubber layer e1 composed of the first rubber strip s1, and a second rubber layer affixed to the outside and having a different composition from the first rubber strip s1. The second rubber layer e2 is formed of a rubber strip s2.

JP 2007-168189 A JP 2007-276268 A

  By the way, in the above-mentioned rubber member, in the first rubber layer e1, the overlapping portions b where the first rubber strips s1 overlap each other and the non-overlapping portions c where the first rubber strips s1 do not overlap are alternately arranged in the axial direction. Formed side by side. Similarly, for the second rubber layer e2, overlapping portions b where the second rubber strips s2 overlap each other and non-overlapping portions c where the second rubber strips s2 do not overlap are formed alternately in the axial direction. Is done.

  However, in the first rubber layer e1 and the second rubber layer e2, there is a problem that when the overlapping portions b and b are overlapped in the radial direction, the surface of the rubber member e becomes uneven. For example, as shown in FIG. 6B, such a rubber member e is easily trapped in air K when bonded to another tire component member f, resulting in poor vulcanization, and the completed tire. There is a problem that durability and strength deteriorate. Alternatively, as shown in FIG. 6B, even if the air is exhausted well, there is a problem that the surface of the rubber member e becomes uneven and the appearance of the tire is deteriorated.

  The present invention has been devised in view of the above-described problems, and in the first rubber layer and the second rubber layer, an overlapping portion and a non-overlapping portion of the rubber strip are formed at optimal positions. The main object is to provide a method for manufacturing a pneumatic tire capable of flattening the surface of a rubber member, effectively preventing air trapping and suppressing poor vulcanization.

The invention according to claim 1 of the present invention is a rubber member in which a first rubber layer comprising a first composition and a second rubber layer comprising a second composition different from the first composition are bonded together. The first rubber strip made of the first composition is spirally wound from one side in the axial direction of the cylindrical molding drum to the other side so that the side edges thereof are overlapped with each other. Forming the first rubber layer in which the overlapping portion where the first rubber strip overlaps and the non-overlapping portion where the first rubber strip does not overlap are aligned in the axial direction, A second rubber strip made of the second composition is spirally wound on the outer side of one rubber layer from one side in the axial direction of the molding drum to the other side so that the side edges thereof overlap each other. Forming a rubber layer of 2 And the step of forming the second rubber layer, the first rubber layer without forming the overlapping portion in which the second rubber strip overlaps the radially outer side of the overlapping portion of the first rubber layer A non-overlapping portion is formed radially outside the non-overlapping portion, and a non-overlapping portion where the second rubber strip does not overlap is formed radially outside the overlapping portion of the first rubber layer. A method for producing a pneumatic tire , wherein the tire is an inner liner layer of a tire and the second rubber layer is a tie gum layer made of a highly adhesive rubber disposed outside the tire of the inner liner. It is.

The invention of claim 2, wherein the first rubber strip and the second rubber strip is the same and manufacturing method of pneumatic tire of claim 1, wherein the wound with a constant winding pitch.

The invention according to claim 3, winding pitch of the first rubber strip, the production of pneumatic tire of claim 2 wherein 0.5 to 0.8 times the width of the first rubber strip Is the method.

  The method for manufacturing a pneumatic tire according to claim 1 is characterized in that the second rubber strip made of the second compound is placed on the outer side of the first rubber layer, and one side in the axial direction of the molding drum so that the side edges thereof overlap each other. Non-overlapping in which the second rubber strip does not overlap with the second rubber strip formed in a spiral manner from one side to the other, forming an overlapping portion where the second rubber strip overlaps on the radially outer side of the non-overlapping portion of the first rubber layer The portion is formed radially outside the overlapping portion of the first rubber layer. Thereby, the thickness of the rubber layer can be made uniform, and residual air generated during vulcanization molding can be suppressed. For this reason, poor vulcanization is suppressed. Moreover, the pneumatic tire manufactured with this manufacturing method can ensure intensity | strength and durability.

It is a right half sectional view of the pneumatic tire of one embodiment of the present invention. It is the elements on larger scale which expand and show the side wall part of FIG. (A) And (B) is sectional drawing for demonstrating the shaping | molding process of a rubber member. (A), (B) is a perspective view which shows an example of the 1st and 2nd rubber strip. It is a figure explaining other embodiment. (A) thru | or (C) is sectional drawing of the rubber layer explaining the prior art.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1 and FIG. 2, a pneumatic tire 1 manufactured by the pneumatic tire manufacturing method of the present embodiment is, for example, a radial tire for passenger cars, and includes a sidewall portion 3 from a tread portion 2. A toroidal carcass 6 reaching the bead core 5 of the bead portion 4, a belt layer 7 disposed on the outer side in the tire radial direction of the carcass 6 and inside the tread portion 2, and disposed on the innermost side in the tire radial direction, The inner liner layer 10 has air impermeability, and a tie gum layer 11 made of a highly adhesive rubber composition disposed between the inner liner layer 10 and the carcass 6. The tie gum layer 11 is preferably arranged at least in the buttress portion region.

  The carcass 6 includes at least one carcass ply 6A in which carcass cords are arranged at an angle of, for example, 75 to 90 ° with respect to the tire equator C. In this example, the carcass ply 6A has both end portions around the bead core 5. It is folded and locked from the inner side to the outer side in the tire axial direction. As the carcass cord, for example, an organic fiber cord such as nylon, polyester, or rayon is preferably used.

  The belt layer 7 is configured by overlapping two belt plies 7A and 7B in which a belt cord is arranged at an angle of, for example, 15 to 35 ° or less with respect to the tire equator C so that the belt cords intersect each other. The The belt cord is preferably a highly elastic cord, particularly a steel cord.

  Further, a side wall rubber 3G is connected to the outer side of the carcass 6 of the side wall portion 3, and a bead rubber 4G (also called clinch rubber) is connected to the inner end of the side wall rubber 3G in the tire radial direction outside the carcass 6 of the bead portion 4. .) Are arranged. Further, the tread portion 2 is provided with a tread rubber 2G on the outer side in the tire radial direction of the belt layer 7.

  The present invention is a pneumatic tire having a rubber member 20 in which a first rubber layer 12 having a first composition and a second rubber layer 13 having a second composition different from the first composition are bonded together. It is a manufacturing method. In the present embodiment, a case where the first rubber layer 12 is the inner liner layer 10 and the second rubber layer 13 is the tie gum layer 11 is shown. Hereinafter, the molding process of the rubber member 20 will be specifically described.

  In the present embodiment, first, as shown in FIG. 3A, a first step of forming the first rubber layer 12 is performed. In the first step, the first rubber strip 14 having the first composition is spirally wound from one side in the axial direction of the cylindrical forming drum d to the other side so that the side edges 14S thereof overlap each other. Is done.

  Specifically, after fixing the winding start end 14X of the first rubber strip 14 continuously supplied from an applicator (not shown) on the molding drum d, the molding drum d is rotated at a constant speed, The applicator is moved at a predetermined constant speed in the axial direction of the forming drum d. Thus, in this step, the first rubber strip 14 is wound at a constant winding pitch P1, and the overlapping portion 14a where the first rubber strips 14 overlap each other and the first rubber strip 14 do not overlap. The first rubber layer 12 (that is, the inner liner layer 10) in which the overlapping portions 14b are alternately arranged in the axial direction is formed. In the present embodiment, the first rubber layer 12 is formed by one turn of the first rubber strip 14.

  For example, as shown in FIG. 4A, the first rubber strip 14 is formed in a ribbon shape having a rectangular cross section which is unvulcanized and has a width W1 larger than the thickness t1. The width W1 and the thickness t1 of the first rubber strip 14 are not particularly limited, but the width W1 is preferably about 5 to 50 mm and the thickness t1 is preferably about 0.5 to 3 mm. When the width W1 is less than 5 mm or the thickness t1 is less than 0.5 mm, it is liable to break when it is spirally wound, and the number of windings may be significantly increased, leading to a decrease in productivity. On the contrary, when the width W1 exceeds 50 mm or when the thickness t1 exceeds 3 mm, it tends to be difficult to form an accurate cross-sectional shape by winding in a spiral shape. The “unvulcanized” refers to the state of rubber that has not been completely vulcanized. Therefore, rubber that has only been pre-vulcanized is included in unvulcanized rubber.

  Further, in order to form the inner liner layer 10, the first rubber strip 14 of the present embodiment employs butyl rubber or butyl rubber compound having excellent air impermeability.

  Next, as shown in FIG. 3B, a second step of forming the second rubber layer 13 on the outside of the first rubber layer 12 is performed. In the second step, the second rubber strip 15 made of the second composition different from the first composition is placed outside the first rubber layer 12 so that the side edges 15S thereof overlap each other. The second rubber layer 13 is formed by spirally winding from one side to the other side in the axial direction. In FIG. 4B, the second rubber strip 15 is shown.

  Specifically, after the winding start end 15X of the second rubber strip 15 continuously supplied from an applicator (not shown) is fixed to the outer surface of the first rubber layer 12, for example, the molding drum d is fixed. While rotating at a speed, the applicator is moved at a predetermined constant speed in the axial direction of the forming drum d. Thus, in this step, the second rubber strip 15 is wound at a constant winding pitch P2, and the overlapping portion 15a where the second rubber strip 15 overlaps with each other and the second rubber strip 15 do not overlap each other. A second rubber layer 13 (that is, the tie gum layer 11) is formed in which the non-overlapping portions 15b are alternately arranged in the axial direction. The second rubber layer 13 of the present embodiment is also formed by one turn of the second rubber strip 15, similarly to the first rubber layer 12.

  The width W2 and thickness t2 of the second rubber strip 15 are preferably set in the same range as the width W1 and thickness t1 for the same reason as the first rubber strip. In the present embodiment, the second rubber strip 15 is formed with substantially the same width and thickness as the first rubber strip 14, but is not limited to such a mode. Further, in order to form the tie gum layer 11, the second rubber strip 14 of the present embodiment employs, for example, a natural rubber rich rubber compound having excellent adhesiveness.

  Further, in the second step, the overlapping portion 15a of the second rubber layer 13 is formed radially outside the non-overlapping portion 14b of the first rubber layer 12, and the non-overlapping portion 15b of the second rubber layer 13 is formed. Is formed on the outer side in the radial direction of the overlapping portion 14 a of the first rubber layer 12. Thereby, as is apparent from FIG. 3B, the outer surface of the rubber member 20 to which the first rubber layer 12 and the second rubber layer 13 are bonded is substantially flattened.

  Thereafter, for example, a sheet-like carcass ply 6A is wound around the outside of the rubber member 20, and after the carcass ply 6A is turned back, the pneumatic tire 1 is manufactured through a shaping process and a vulcanization process in accordance with customary practice. By adopting such a method, it is possible to obtain a raw cover that can prevent large air from being confined between the rubber member 20 and the carcass ply 6A as well as between the rubber members 20, and the bare during vulcanization can be obtained. The occurrence of defects such as these can be suppressed.

  Further, when the interface between the first rubber layer 12 and the second rubber layer 13 has a rectangular wave shape like a rack gear, a physical intermeshing bond occurs between the rubber layers 12 and 13, and anti-peeling It also helps to increase performance. Furthermore, since the thickness of the rubber member 20 becomes uniform, it is possible to prevent the surface of the inner liner layer 10 from becoming uneven after the tire vulcanization molding and to improve the appearance of the tire.

  In the embodiment of FIG. 3, the first rubber strip 14 and the second rubber strip 15 are wound with, for example, the same and constant winding pitches P1 and P2 (P1 = P2 = constant). Accordingly, for example, the winding of the first rubber strip 14 is temporarily stopped halfway, and the winding start end 15X of the second rubber strip 15 is fixed on the first rubber strip 14, and then both applicators are moved. Simultaneous winding that synchronizes the speed can be performed, and productivity can be improved.

  Further, if the winding pitch P1 of the first rubber strip 14 is too small, the region of the non-overlapping portion 14b is also reduced. As a result, the overlapping portion 14a of the second rubber strip 15 is accurately set to the non-overlapping portion 14b. It tends to be difficult to form the outer layers. From such a viewpoint, the winding pitch P1 is preferably 0.5 times or more, more preferably 0.6 times or more the width W1 of the first rubber strip 14, and the upper limit thereof is 1. Less than 0 times. In the above embodiment, the winding pitches P1 and P2 of the first and second rubber strips 14 and 15 are both about 0.66 times.

  In the case of the embodiment of FIG. 3, when the cross-sectional areas of the first rubber strip 14 and the second rubber strip 15 are the same, the first rubber layer 12 and the second rubber layer 13 per unit axial length. It can be formed with substantially the same rubber volume.

  FIG. 5 shows another embodiment of the present invention. In this embodiment, the winding pitch P1 of the first rubber strip 14 and the winding pitch P2 of the second rubber strip 15 are different. In the present embodiment, P1> P2 is set. In this embodiment, when the cross-sectional areas of the first rubber strip 14 and the second rubber strip 15 are the same, the rubber volume of the second rubber layer 13 per unit axial length is set to the first rubber layer 12. It can be larger than the rubber volume. Therefore, for example, it is effective to increase the rubber volume of the tie gum layer 11 and to achieve durability.

  As mentioned above, although the 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. For example, when the sidewall rubber 3G, the bead rubber 4G, and / or the tread rubber 2G are composed of two kinds of rubber blends, the present invention can be applied to these rubber members.

  In order to confirm the effect of the present invention, a passenger car radial tire of size 215 / 45R17 was prototyped based on the specifications shown in Table 1 and tested for the presence or absence of bears and aesthetics. The first rubber layer was employed as the inner liner layer, and the second rubber layer was employed as the tie gum layer. The first rubber strip and the second rubber strip had the same width of 23 mm and a thickness of 1.1 mm.

Regarding the presence or absence of bears, 1000 tires were vulcanized and molded under each condition, and the number of bears was measured. Further, in the aesthetic test, the smoothness of the inner liner layer forming the tire cavity surface was evaluated based on the sensuality of 10 general users (average value of n = 10). The results are indicated by a score of 100, which is the example with the highest evaluation.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that by forming the overlapping portion and the non-overlapping portion in the tire radial direction, generation of bears was suppressed and a good appearance was exhibited.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 12 1st rubber layer 13 2nd rubber layer 14 1st rubber strip 14a 1st rubber strip overlap part 14b 1st rubber strip non-overlap part 14S Side edge of 1st rubber strip 15 Second rubber strip 15a Second rubber strip overlap portion 15b Second rubber strip non-overlap portion 15S Side edge 20 of second rubber strip Rubber member d Molding drum

Claims (3)

A method for producing a pneumatic tire having a rubber member obtained by bonding a first rubber layer composed of a first composition and a second rubber layer composed of a second composition different from the first composition,
The first rubber strip is formed by spirally winding the first rubber strip having the first composition from one side in the axial direction to the other side of the cylindrical molding drum so that the side edges thereof overlap each other. Forming the first rubber layer in which the overlapping portion where the first rubber strips overlap and the non-overlapping portion where the first rubber strip does not overlap are aligned in the axial direction;
A second rubber strip made of the second compound is spirally wound on the outer side of the first rubber layer from one side in the axial direction of the molding drum to the other side so that the side edges thereof overlap each other. Forming a second rubber layer, and the step of forming the second rubber layer includes a step of forming an overlapping portion where the second rubber strip is overlapped with a radius of the overlapping portion of the first rubber layer. A non-overlapping portion that does not overlap the second rubber strip is formed in the radial direction of the non-overlapping portion of the first rubber layer without being formed outside in the direction. Formed on the outside ,
The first rubber layer is an inner liner layer of a pneumatic tire, and the second rubber layer is a tie gum layer made of a highly adhesive rubber disposed outside the tire of the inner liner. A method for producing a pneumatic tire.   The method for producing a pneumatic tire according to claim 1, wherein the first rubber strip and the second rubber strip are wound at the same and constant winding pitch.   The method for manufacturing a pneumatic tire according to claim 2, wherein a winding pitch of the first rubber strip is 0.5 to 0.8 times a width of the first rubber strip.

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