JP6450207B2 - Pneumatic tire manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire that suppresses air accumulation between a side rubber and a cylindrical carcass.

  As shown in FIG. 7, in the raw tire manufacturing stage, a side rubber c including a side wall rubber is generally attached to the outside of a cylindrical carcass b formed on the molding drum a. At this time, the side rubber c is pressed using the pressing roller d, and thereby the air between the side rubber c and the cylindrical carcass b is discharged. Note that a wide sponge roller is generally used as the pressing roller d (see, for example, Patent Document 1).

  However, since the thickness of the cylindrical carcass b and the side rubber c is not uniform, the outer surface of the side rubber c on the molding drum a is inflected in an uneven shape. For this reason, even if a sponge roller is used as the pressing roller d, there is a problem that the pressing force is insufficient at a low height portion, air is trapped at that portion, and the tire quality is deteriorated.

JP 2006-231616 A

  Therefore, an object of the present invention is to provide a method for manufacturing a pneumatic tire that can effectively discharge air between the side rubber and the cylindrical carcass and can suppress the occurrence of air accumulation and improve the tire quality.

The present invention includes a carcass forming step of forming a cylindrical carcass on a forming drum;
A side rubber forming step of forming a side rubber formed at least on the outer surface of the side wall portion on the outside of the cylindrical carcass;
Including a side rubber pressing step of pressing the side rubber against the cylindrical carcass by pressing means having a pressing roller,
The outer peripheral surface of the forming drum extends parallel to the drum axis in the meridional section including the drum axis,
In the side rubber pressing step, the pressing roller is parallel to the drum axis from one end side to the other end side in the drum axial direction of the side rubber while pressing the outer peripheral surface of the side rubber and rolling in the drum circumferential direction. It is guided and exhausts air between the side rubber and the cylindrical carcass.

  In the method for manufacturing a pneumatic tire according to the present invention, it is preferable that the pressing unit includes an air cylinder that supports the pressing roller, and the pressing roller presses the side rubber by the air cylinder.

In the method for manufacturing a pneumatic tire according to the present invention, the carcass forming step includes:
A winding step of winding a sheet-like carcass ply in a cylindrical shape on the forming drum;
A bead core setting step of setting an annular bead core at a position spaced inward in the drum axial direction from both ends of the cylindrical carcass ply;
It is preferable that the method further includes a step of turning back a protruding portion of the carcass ply that protrudes outward from the bead core in the drum axial direction around the bead core.

In the method for manufacturing a pneumatic tire according to the present invention, the side rubber includes a first rubber portion on the tread side and a second rubber portion on the bead side,
Moreover, prior to the folding step, the second rubber portion is attached to the inside of the protruding portion in the radial direction, and is turned to the outside in the radial direction of the protruding portion along with the folding step,
The first rubber part is composed of a first rubber part and a second rubber part by being attached on the inner end part in the drum axial direction of the second rubber part that has been changed in direction so as to have an overlapping part. Side rubber is formed on the outside of the cylindrical carcass,
In the side rubber pressing step, it is preferable that the pressing roller moves from the first rubber part side to the second rubber part side.

  In the present invention, by using a narrow pressing roller, the side rubber can be pressed while following the irregularities on the outer surface of the side rubber, and insufficient pressing force at the concave portion can be suppressed.

  Further, the pressing roller moves in the drum axis direction from one end side of the side rubber in the drum axis direction to the other end side while pressing on the outer peripheral surface of the side rubber and rolling in the drum circumferential direction. Therefore, the air between the side rubber and the cylindrical carcass can be gradually pushed out from one end side to the other end side, and combined with the suppression of the insufficient pressing force, it is effective to generate an air pocket between the side rubber and the cylindrical carcass. Can be suppressed.

It is sectional drawing which shows one Example of the pneumatic tire formed by the manufacturing method of this invention. It is a conceptual diagram which shows a carcass formation process. It is a conceptual diagram which shows the order of attachment of each member in a carcass formation process. It is sectional drawing which shows a side rubber formation process. It is sectional drawing which shows a side rubber pressing process. (A)-(C) are sectional drawings which show the other example of 1st stage. It is sectional drawing which shows the conventional pressing method of a side rubber.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 shows an example of a pneumatic tire 1 formed by the manufacturing method of the present invention. The pneumatic tire 1 of the present example is a pneumatic tire for a passenger car, and includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, the inside of the tread portion 2 and the above-described A belt layer 7 disposed on the radially outer side of the carcass 6.

  The carcass 6 is formed of one or more carcass plies 6A in this example, in which carcass cords are arranged at an angle of, for example, 75 to 90 ° with respect to the tire circumferential direction. The carcass ply 6 </ b> A has a ply turn-back portion 6 b that is turned around the bead core 5 at both ends of a toroid-like ply main body portion 6 a that extends between the bead cores 5 and 5. Further, a bead apex rubber 8 for bead reinforcement that extends in a tapered manner from the bead core 5 to the outer side in the tire radial direction is disposed between the ply body portion 6a and the ply turn-up portion 6b.

  The belt layer 7 is formed of two or more belt plies 7A and 7B in this example, in which belt cords are arranged at an angle of, for example, 10 to 35 ° with respect to the tire circumferential direction. The belt cords cross each other between the plies, thereby increasing the belt rigidity and reinforcing the substantially entire width of the tread portion 2 with a tagging effect.

  Inside the carcass 6, an inner liner rubber 10 made of a non-air permeable rubber such as butyl rubber and forming a tire lumen surface is disposed. Further, on the outside of the carcass 6, a sidewall rubber 3 </ b> G that forms the outer surface of the sidewall portion 3 and a clinch rubber 4 </ b> G that forms the outer surface of the bead portion 4 are disposed. The radially inner end of the sidewall rubber 3G is continuous with the radially outer end of the clinch rubber 4G. In this example, the side rubber 11 is constituted by the side wall rubber 3G and the clinch rubber 4G.

  Reference numeral 12 in the figure is a chafer for preventing rim displacement made of canvas cloth or the like. The chafer 12 includes a chafer main body 11A that forms the bottom surface of the bead portion 4, an outer rising portion 12B that is bent at the outer end in the tire axial direction and extends in contact with the outer surface of the ply turnup portion 6b, and a tire shaft of the chafer main body 12A. The outer rising portion 12C is bent at the inner end in the direction and extends along the tire cavity surface.

  Next, a method for manufacturing the pneumatic tire 1 will be described. This manufacturing method includes a raw tire forming step for forming a raw tire and a vulcanization step for vulcanizing and forming the formed raw tire in a mold. The raw tire forming step includes a 1st stage and a 2nd stage, and in the 1st stage, a cylindrical base tire (not shown) is formed using a molding drum 15 having a 1st former. In the 2nd stage, a shaping drum that is a 2nd former is used to inflate the base tire in a toroid shape, and a tread forming member is joined to the inflated portion to form a raw tire.

  In the production method of the present invention, conventional processes can be suitably employed for the 2nd stage and the vulcanization process. Therefore, only the 1st stage will be described below.

  The 1st stage includes a carcass forming step S1, a side rubber forming step S2, and a side rubber pressing step S3.

  As shown in FIG. 2, in the carcass forming step S <b> 1, a cylindrical carcass 106 is formed on the forming drum 15. Specifically, the carcass forming step S1 of this example includes a winding step S1a, a bead core setting step S1b, and a turn-back step S1c.

  In the winding step S1a, a sheet-like carcass ply 106A is wound in a cylindrical shape on the forming drum 15. Strictly, as shown in FIG. 3 conceptually showing the mounting order of the members, in this example, the chafer 112 and the inner liner rubber 110 are sequentially arranged on the forming drum 15 prior to the mounting of the carcass ply 106A. Is done. In FIG. 2, the chafer 112 and the inner liner rubber 110 are omitted.

  In the bead core setting step S1b, the annular bead core 105 is set at a position P separated from both ends of the cylindrical carcass ply 106A in the drum axial direction. In this example, the forming drum 15 includes a central drum portion 15a, a side drum portion 15b, and a step portion 15c therebetween. After the both ends of the cylindrical carcass ply 106A are narrowed down along the step portion 15a, the bead core 105 is set at the position P of the step portion 15a. A bead apex rubber 108 is integrally joined to the bead core 105 in advance.

  As the forming drum 15, for example, the sheet-like carcass ply 106A is wound in the state where the central drum portion 15a and the side drum portion 15b have the same diameter (winding step S1a), and then the central drum portion 15a is expanded. Thus, the step portion 15a can be formed. In this case, since it is not necessary to narrow down the both ends of the carcass ply 106A, there is an advantage that the disturbance of the carcass cord due to this narrowing can be suppressed. Further, since the central drum portion 15a and the side drum portion 15b have the same diameter, there is an advantage that the winding accuracy of the chafer 112, the inner liner rubber 110, and the carcass ply 106A can be improved.

  In the folding step S 1 c, the protruding portion 106 b of the carcass ply 106 A that protrudes outward from the bead core 105 in the drum axis direction is folded back around the bead core 105 in the drum axis direction. The protruding portion 106b is a portion corresponding to the ply folding portion 6b of the pneumatic tire 1 and is folded by the existing folding means 17 including the bladder 17A. The bladder 17A is provided in the side drum portion 15b.

  Thus, in this example, the cylindrical carcass 106 is formed as the carcass ply 106A in a state where the protruding portion 106b is folded back.

  As shown in FIG. 4, in the side rubber forming step S2 of this example, the side rubber 111 in which the side wall rubber 103G and the clinch rubber 104G are integrally joined in advance is formed outside the cylindrical carcass 106 including the folded-back protruding portion 106b. This is done by winding.

  As shown in FIG. 5, in the side rubber pressing step S <b> 3, the side rubber 111 is pressed against the cylindrical carcass 106 by the pressing means 19 having the pressing roller 18.

  Specifically, in the side rubber pressing step S3, the pressing roller 18 presses on the outer peripheral surface of the side rubber 111 and rolls in the drum circumferential direction, while the side rubber 111 rotates from the one end E1 side in the drum axial direction to the other end E2. Move in the drum axis direction. Thereby, the air between the side rubber 111 and the cylindrical carcass 6 is effectively discharged.

  The pressing means 19 of this example includes a moving table 21 supported by a guide 20 so as to be movable in the drum axis direction, an air cylinder 22 attached to the moving table 21, and a lower end of the rod via a roller holder 23. The pressing roller 18 is provided.

  The guide tool 20 includes, for example, a pair of guide shafts 20A extending in the drum shaft direction, and a ball screw shaft 20B parallel to the guide shaft 20A. The ball screw shaft 20B is rotationally driven by a motor (not shown) connected to one end thereof. In addition, the movable base 21 has a block shape in this example, and includes a bearing hole 21A guided by the guide shaft 20A and a screw hole 21B screwed to the ball screw shaft 20B. Therefore, the movable table 21 can freely move in the drum axis direction by the rotation of the ball screw shaft 20B.

  A pressing roller 18 is supported on the lower end of the rod of the air cylinder 22 via a roller holder 23 so as to be rotatable in the drum circumferential direction.

  The pressing roller 18 has a width Wr of preferably 1/5 or less, more preferably 1/10 or less, and further preferably 1/15 or less of the width Wg of the outer surface of the side rubber 111 in the drum axis direction. Laura. The width Wg is defined as the width in the drum axis direction when the side rubber 111 is disposed on the cylindrical carcass 106.

  In the pressing means 19 configured as described above, the pressing roller 18 is narrow, so that the side rubber 111 can be pressed against the cylindrical carcass 106 while following the irregularities on the outer surface of the side rubber 111, and the pressing force at the concave portion is insufficient. Can be suppressed. Moreover, the pressing roller 18 moves in the drum axial direction from the drum shaft direction one end E1 side to the other end E2 side of the side rubber 111 while rolling in the drum circumferential direction. Therefore, the air between the side rubber 111 and the cylindrical carcass 106 can be gradually pushed out from the one end E1 side to the other end E2 side, coupled with the suppression of the pressing force shortage, and between the side rubber 111 and the cylindrical carcass 106. Generation of air pockets can be effectively suppressed. One end E1 side is preferably the tread side, and the other end E2 side is preferably the bead side. The movement pitch P (movement distance per drum rotation) of the pressing roller 18 is 1.0 times or less, preferably 0.9 times or less the width Wr of the pressing roller 18.

  Further, by using the air cylinder 22, it can be pressed with a uniform force. The pressing roller 18 is preferably a hard roller made of, for example, rubber, metal, synthetic resin or the like that is not compressed and deformed by the pressing force. In order to easily move in the drum axis direction, it is preferable that both end portions of the pressing roller 18 are formed by arcuate surfaces 18E.

  FIG. 6 shows a second embodiment of the 1st stage. As shown in FIG. 6C, the side rubber 111 is composed of a first rubber portion 111A on the tread side that is the sidewall rubber 103G and a second rubber portion 111B on the bead side that is the clinch rubber 104G. In the second embodiment, the second rubber portion 111B attaches to the inside in the radial direction of the protruding portion 106b of the carcass ply 106A prior to the folding step S1c.

  Specifically, as shown in FIG. 6A, in the winding step S1a of this example, the second rubber portion is formed on the molding drum 15 having the same diameter of the central drum portion 15a and the side drum portion 15b. 111B (clinch rubber 104G), chafer 112, inner liner rubber 110, and carcass ply 106A are sequentially wound into a cylindrical shape. Accordingly, at least the second rubber portion 111B is attached to the radially inner side of the protruding portion 106b.

  Thereafter, as shown in FIG. 6B, the diameter of the central drum portion 15a is increased, and a step portion 15c is formed between the central drum portion 15b and the side drum portion 15b. In the bead core setting step S1b, the bead core 105 in which the bead apex rubber 108 is integrally joined is set at the position P of the step portion 15c. The bead apex rubber 108 is tilted inward in the drum axial direction and is attached to the carcass ply 106A.

  As shown in FIG. 6C, in the folding step S1c, the protruding portion 106b is folded around the bead core 105 inward in the drum axis direction. Along with this folding, the second rubber portion 111B (clinch rubber 104G) turns to the outside in the radial direction of the protruding portion 106b.

Then, the first rubber portion 111A is pasted with an overlapping portion J on the inner end portion in the drum axis direction of the second rubber portion 111B that has been redirected. Thereby, the side rubber 111 in which the first rubber part 111A and the second rubber part 111B are connected is formed outside the cylindrical carcass 106.
Further, in the side rubber pressing step S3, as in FIG. 5, the pressing roller 18 presses on the outer peripheral surface of the side rubber 111 and rolls in the drum circumferential direction, and from the first rubber portion side to the second rubber portion 111B. Move to the side. Since the first rubber part 111A overlaps the outside of the second rubber part 111B, the first rubber part 111A can move smoothly on the overlapping part J by moving from the first rubber part 111A side to the second rubber part 111B side. At the same time, air pockets generated in the overlapping portion J can be exhausted.

  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.

  In order to confirm the effect of the present invention, the pressing roller shown in FIG. 5 is used to press the outer peripheral surface of the side rubber formed on the outer side of the cylindrical carcass and roll in the drum circumferential direction from one end side of the side rubber. The drum was moved in the drum axial direction toward the other end, thereby exhausting air between the side rubber and the cylindrical carcass. The side rubber is formed according to the second embodiment shown in FIG.

  As a comparative example, a wide pressing roller made of sponge shown in FIG. 7 is used, and it is rolled in the drum circumferential direction while pressing the outer peripheral surface of the side rubber without moving in the drum axial direction. The air between the carcass was exhausted. In the embodiment, the width Wr of the pressing roller is 1/20 of the width Wg of the side rubber.

  Then, the formed raw tire was vulcanized, and it was confirmed whether or not air accumulation occurred in the sidewall portion of the tire after vulcanization. In the tire of the comparative example, air retention occurred, but in the tire of the example, no air retention occurred.

15 Forming drum 18 Pressing roller 19 Pressing means 22 Air cylinder 105 Bead core 106 Cylindrical carcass 106A Carcass ply 106b Protruding part 111 Side rubber 111A First rubber part 111B Second rubber part J Overlapping part P Position S1 Carcass forming step S1a Winding step S1b Bead core setting step S1c Folding step S2 Side rubber forming step S3 Side rubber pressing step P Position

Claims (4)

A carcass forming step of forming a cylindrical carcass on a forming drum;
A side rubber forming step of forming a side rubber formed at least on the outer surface of the side wall portion on the outside of the cylindrical carcass;
Including a side rubber pressing step of pressing the side rubber against the cylindrical carcass by pressing means having a pressing roller,
The outer peripheral surface of the forming drum extends parallel to the drum axis in the meridional section including the drum axis,
In the side rubber pressing step, the pressing roller is parallel to the drum axis from one end side to the other end side in the drum axial direction of the side rubber while pressing the outer peripheral surface of the side rubber and rolling in the drum circumferential direction. A method for producing a pneumatic tire, characterized in that air is guided and exhausted between a side rubber and a cylindrical carcass.   The method of manufacturing a pneumatic tire according to claim 1, wherein the pressing means includes an air cylinder that supports the pressing roller, and the pressing roller presses the side rubber by the air cylinder. The carcass forming step includes
A winding step of winding a sheet-like carcass ply in a cylindrical shape on the forming drum;
A bead core setting step of setting an annular bead core at a position spaced inward in the drum axial direction from both ends of the cylindrical carcass ply;
The method for producing a pneumatic tire according to claim 1 or 2, further comprising a step of turning back a protruding portion of the carcass ply that protrudes outward in the drum axial direction from the bead core, inwardly in the drum axial direction around the bead core. . The side rubber consists of a first rubber part on the tread side and a second rubber part on the bead side,
Moreover, prior to the folding step, the second rubber portion is attached to the inside of the protruding portion in the radial direction, and is turned to the outside in the radial direction of the protruding portion along with the folding step,
The first rubber part is composed of a first rubber part and a second rubber part by being attached on the inner end part in the drum axial direction of the second rubber part that has been changed in direction so as to have an overlapping part. Side rubber is formed on the outside of the cylindrical carcass,
4. The method of manufacturing a pneumatic tire according to claim 3, wherein, in the side rubber pressing step, the pressing roller moves from the first rubber portion side to the second rubber portion side.

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