JP6196433B2 - Pneumatic tire manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire capable of improving the detachability of a rigid core.

  In recent years, in order to improve the uniformity of a tire, a method of manufacturing a pneumatic tire using a rigid core having an outer surface for forming the inner cavity surface of the tire has been proposed (see Patent Document 1 below). The rigid core is assembled, for example, by connecting a plurality of segments in the tire circumferential direction. Such a rigid core can take out each segment from a pneumatic tire by sequentially moving each segment inward in the tire radial direction.

  In a method for manufacturing a pneumatic tire using a rigid core, first, a raw tire forming step is performed in which a tire member is attached to the outer surface of the rigid core to form a raw tire. Next, a vulcanization process is performed in which the raw tire is vulcanized together with the rigid core. And the rigid core removal process which takes out each segment from the vulcanized tire is performed.

  Further, in the raw tire forming step, for example, a tape-shaped rubber strip g is spirally formed on the outer surface b of the rigid core a as shown in FIG. And an inner liner forming step of forming an inner liner d.

JP-A-11-254906

  Generally, in a pneumatic tire, a sidewall portion protrudes outward in the tire axial direction from a bead portion. For this reason, the outer surface b of the rigid core a is also formed such that the sidewall molding surface b1 that forms the sidewall portion protrudes outward in the tire axial direction from the bead molding surface b2 that forms the bead portion.

  For this reason, as shown in FIG. 11 (b), in the rigid core removing step, the bead portion f of the tire e is expanded outward in the tire axial direction by the radial movement of the rigid core a. Thereby, a big friction tends to arise between the lumen | bore surface h of the bead part f, and the side wall molding surface b1 of the rigid core a. Such a large friction has a problem in that the rubber strip g of the inner liner d forming the inner cavity surface h is easily peeled off, and the detachability of the rigid core a is easily lowered.

  The present invention has been devised in view of the actual situation as described above, and a tape-shaped rubber strip is placed on each of a pair of bead molding surfaces of a rigid core from the outside in the tire radial direction while overlapping the side edges thereof. Mainly to provide a manufacturing method of a pneumatic tire capable of improving the removability of a rigid core based on forming a bead portion side region of an inner liner by pasting in a spiral shape on the inner side in the tire radial direction. Yes.

The invention according to claim 1 of the present invention is a method for manufacturing a pneumatic tire having a sidewall portion projecting outward in the tire axial direction from the bead portion by core molding, and includes a plurality of segments. Are connected in the tire circumferential direction to form an outer surface that forms a lumen surface of the pneumatic tire, and each segment is moved inward in the tire radial direction in order to move each segment from the pneumatic tire. A raw tire forming step of forming a raw tire by attaching a tire member to the outer surface of an assembling-type rigid core from which a segment can be taken out, and a vulcanization mold including a cavity for forming the outer surface of the raw tire to, the raw tire was put together with the rigid core, the vulcanization process to obtain a vulcanized tire by vulcanizing the raw tire, said from the vulcanized tire each cell Instruments to be moved radially inward tire, wherein and a rigid core removal step of removing the rigid core from the vulcanized tire, said raw tire forming step, of the outer surface of the rigid core, At least a pair of bead forming surfaces for forming the bead part, a tape-like rubber strip is spirally attached from the outer side in the tire radial direction to the inner side in the tire radial direction while overlapping the side edges thereof, and the bead of the inner liner is attached. It includes an inner liner forming step for forming a part side region.

  According to a second aspect of the present invention, the rubber strip includes a side edge of the outer surface of the rigid core at least in a region radially inward from a maximum width position of the rigid core in the tire axial direction. The method for manufacturing a pneumatic tire according to claim 1, wherein the tires are attached in a spiral shape from the outer side in the tire radial direction to the inner side in the tire radial direction while overlapping each other.

  According to a third aspect of the present invention, in the rubber strip, the outer radius of the rigid core is overlapped with each other in a region radially inward of the tire core from the equator of the rigid core while overlapping the side edges thereof. It is a manufacturing method of the pneumatic tire of Claim 1 or 2 affixed on the inside of a tire radial direction from the direction outer side in a spiral shape.

  The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3, wherein the rubber strip has a width of 5 to 25 mm and a thickness of 0.3 to 1.5 mm. It is a manufacturing method.

  The invention according to claim 5 is the pneumatic tire according to any one of claims 1 to 4, wherein the overlapping portion where the side edges of the rubber strip overlap is 50% or less of the width of the rubber strip. It is a manufacturing method.

  The method for producing a pneumatic tire of the present invention includes a raw tire forming step of forming a raw tire by attaching a tire member to an outer surface of a rigid core, a vulcanizing step of vulcanizing the raw tire together with the rigid core, A rigid core removing step of removing the rigid core from the vulcanized tire.

  The rigid core is formed with an outer surface that forms a lumen surface of a pneumatic tire by connecting a plurality of segments in the tire circumferential direction. Further, the rigid core is taken out from the pneumatic tire by sequentially moving the segments inward in the tire radial direction.

  The raw tire forming step includes a tape-shaped rubber strip on each of a pair of bead forming surfaces for forming at least a bead portion of the outer surface of the rigid core, and a tire radius from the outer side in the tire radial direction while overlapping the side edges with each other. It includes an inner liner forming step of forming a bead portion side region of the inner liner by being attached in a spiral shape on the inner side in the direction.

  In the bead portion side region of the inner liner, the side edge of the rubber strip on the outer side in the tire radial direction is covered with the adjacent rubber strip on the outer side in the radial direction on the inner cavity surface of the pneumatic tire. Thereby, the bead part side area | region can prevent that a rubber strip is upside down by the movement to the tire radial direction inner side of each segment. Therefore, in the manufacturing method of this invention, peeling of a rubber strip can be prevented effectively and the removal property of a rigid core can be improved.

It is sectional drawing which shows an example of the pneumatic tire manufactured with the manufacturing method of this embodiment. It is a disassembled perspective view which shows an example of a rigid core. It is sectional drawing of the rigid core in which the green tire was formed. It is the side view which looked at the core main body from the axial direction. It is sectional drawing of the green tire formed in the outer surface of a rigid core. It is sectional drawing explaining a vulcanization | cure process. It is an exploded sectional view explaining a rigid core removal process. It is sectional drawing explaining an example of an inner liner formation process. It is a perspective view which shows a rubber strip. (A) is the elements on larger scale of FIG. 8, (b) is a fragmentary sectional view which shows the bead part pushed and expanded to the tire axial direction outer side by the segment. (A) is sectional drawing explaining the conventional inner liner formation process, (b) is sectional drawing explaining a rigid core removal process.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
A method for manufacturing a pneumatic tire according to the present embodiment (hereinafter sometimes simply referred to as “manufacturing method”) includes a pneumatic tire (hereinafter also simply referred to as “tire”) using a rigid core. This is a method of manufacturing by child molding.

  As FIG. 1 shows, the tire 1 of this embodiment is comprised as a radial tire for passenger cars. The tire 1 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, and a belt layer 7 disposed on the outer side in the tire radial direction of the carcass 6 and inside the tread portion 2. An inner liner 9 disposed inside the carcass 6 is provided. In addition, the tire 1 is formed so that the sidewall portion 3 protrudes outward in the tire axial direction from the bead portion 4 at the time of 5% internal pressure filling, for example.

  “At the time of 5% internal pressure filling” is a state in which the tire 1 is assembled on the normal rim and is reduced from an unloaded normal state in which the normal internal pressure is filled to an internal pressure of 5% of the internal normal pressure.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, the standard rim for JATMA, “Design Rim” for TRA, or ETRTO If there is, “Measuring Rim”.

  “Regular internal pressure” is the air pressure standardized for each tire. If it is JATMA, it is the maximum air pressure. “INFLATION PRESSURE”, but when tire 1 is for a passenger car, the pressure is uniformly 180 kPa.

  The carcass 6 is composed of one or more radial structures in which carcass cords are arranged at an angle of, for example, 75 to 90 ° with respect to the tire equator C, and in this embodiment, one carcass ply 6A. For the carcass cord, for example, an organic fiber cord such as polyester or a steel cord is employed.

  The carcass ply 6 </ b> A extends from the tread portion 2 through a pair of sidewall portions 3, 3 across the bead portions 4, 4 in a toroidal shape. In the carcass ply 6 </ b> A of the present embodiment, the inner end 6 e in the tire radial direction terminates without being wound up by the bead portion 4.

  The bead core 5 includes an inner core 5A disposed on the inner surface in the tire axial direction and an outer core 5B disposed on the outer surface in the tire axial direction on the inner end 6e side of the carcass ply 6A. The inner core 5A and the outer core 5B are formed by winding one bead wire 5c in a spiral shape in the tire circumferential direction.

  Further, an inner apex rubber 8i is disposed on the inner surface of the inner core 5A in the tire axial direction. Further, an outer apex rubber 8o is disposed on the outer surface of the outer core 5B in the tire axial direction. These apex rubbers 8i and 8o are made of hard rubber.

  The belt layer 7 includes at least two belt plies 7A arranged in such a manner that the belt cord is inclined with respect to the tire equator C at a small angle of, for example, 10 to 40 °, and in this embodiment, two outer belt plies 7A in the tire radial direction. , 7B. These belt plies 7A and 7B are overlapped so that the belt cords cross each other. In addition, for example, a steel cord or an organic fiber cord such as aramid is adopted as the belt cord.

  The inner liner 9 is disposed in almost the entire area of the lumen surface 17 across the pair of bead cores 5 and 5 in a toroidal shape. The inner liner 9 is made of, for example, an air impermeable rubber material having a thickness t of about 0.5 to 2.0 mm. The air-impermeable rubber is, for example, a butyl system in which 60 parts by mass or more, preferably 80 parts by mass or more, and more preferably 100 parts by mass of butyl rubber (or a derivative thereof) in 100 parts by mass of the rubber component. Rubber can be preferably used.

  As shown in FIGS. 2 and 3, the rigid core 10 includes an annular core body 11, a core 12 inserted into the center hole 11 h of the core body 11, and an axial direction of the core body 11. A pair of side wall bodies 13L and 13U are provided on both sides of each other.

  The core body 11 is composed of a plurality of segments 14 having different sizes divided in the tire circumferential direction. As shown in FIG. 4, the segment 14 of the present embodiment includes a first segment 14A in which the circumferential length L1 gradually decreases inward in the tire radial direction, and the circumferential length L2 inward in the tire radial direction. A second segment 14B that gradually increases toward the center is included. The first segments 14A and the second segments 14B are alternately arranged in the tire circumferential direction.

  Such a core main body 11 can be disassembled by sequentially moving the second segment 14B and the first segment 14A inward in the tire radial direction. Further, the core body 11 is assembled by connecting the segments 14A and 14B in the tire circumferential direction, thereby forming an outer surface 18 for molding the lumen surface 17 of the tire 1 as shown in FIG. For example, the outer surface 18 of the present embodiment approximates the inner surface shape of the tire 1 when filled with 5% internal pressure.

  As shown in FIG. 5, on the outer surface 18, a tread molding surface 18a for molding the lumen surface 17 of the tread portion 2 of the tire 1, a sidewall molding surface 18b for molding the lumen surface 17 of the sidewall portion 3, And the bead shaping | molding surface 18c which shape | molds the lumen | bore surface 17 of the bead part 4 is included. In the present embodiment, the sidewall molding surface 18b is formed so as to protrude outward in the tire axial direction from the bead molding surface 18c. Further, a maximum width position 20 that protrudes most outward in the tire axial direction is provided on the sidewall molding surface 18b.

  As shown in FIG. 2, the core 12 is formed in a cylindrical shape. As shown in FIG. 3, the core 12 is inserted into the center hole 11 h of the core body 11. As a result, the core 12 can prevent the first segment 14A and the second segment 14B from moving inward in the radial direction.

  2, dovetail grooves 19a extending in the axial direction of the rigid core 10 and engaging with each other on the outer peripheral surface of the core 12 and the inner peripheral surfaces of the segments 14A and 14B, Or the ant tenon 19b is formed, respectively. Thereby, the core 12 and the segments 14A and 14B are connected so as to be relatively movable only in the axial direction.

  One side wall 13L is fixed to one side of the core 12 in the axial direction. The other side wall 13U is fixed to the other side of the core 12 in the axial direction. Further, the other side wall body 13U is detachably screwed through an inner screw portion 15 provided in the center hole 12h of the core 12. As shown in FIG. 3, the pair of side wall bodies 13L and 13U can prevent the core 12 from moving in the axial direction and hold the core body 11 and the core 12 together. it can.

  Each of the side wall bodies 13L and 13U is provided with a support shaft portion 16 projecting outward in the axial direction on the outer surface thereof. For example, the support shaft portion 16 is detachably connected to a chuck portion 23 such as a transport device (not shown) that transports the rigid core 10 to a vulcanization mold or the like.

Next, the manufacturing method of this invention is demonstrated.
As shown in FIG. 5, in the manufacturing method of the present embodiment, first, a raw tire forming step S <b> 1 is performed in which a raw tire 1 </ b> L is formed by attaching an unvulcanized tire member or the like to the outer surface 18 of the rigid core 10. Done. Here, the term “unvulcanized” includes all embodiments that have not been completely vulcanized. Therefore, the so-called semi-vulcanized state is included in this “unvulcanized”.

  In the raw tire forming step S1 of the present embodiment, an inner liner forming step S11 for forming the inner liner 9 is attached to the outer surface 18 of the rigid core 10, and a tire member such as the carcass ply 6A is attached to the outside of the inner liner 9. Affixing step S12 is performed.

  In the inner liner forming step S11, the inner liner 9 is attached to the outer surface 18 of the rigid core 10 across the pair of bead molding surfaces 18c and 18c. In the attaching step S12, for example, the carcass ply 6A, the cores 5A and 5B, the apex rubbers 8i and 8o, the side wall rubber 3G, the belt layer are formed on the outer surface 18 of the rigid core 10 to which the inner liner 9 is attached. 7, tread rubber 2G and the like are attached in order. Thereby, the raw tire 1 </ b> L is formed on the outer surface 18 of the rigid core 10.

  Next, a vulcanization step S2 for vulcanizing the raw tire 1L together with the rigid core 10 is performed. As shown in FIG. 6, in the vulcanization step S2, a vulcanization mold 22 having a cavity 22s that forms the outer surface of the raw tire 1L is used. In this vulcanization mold 22, the raw tire 1L is put together with the rigid core 10, and the raw tire 1L is vulcanized. After the vulcanization is completed, the vulcanized tire 1 is taken out from the vulcanization mold 22 together with the rigid core 10.

  Next, a rigid core removing step S3 for removing the rigid core 10 from the vulcanized tire 1 is performed. In the rigid core removing step S3, as shown in FIG. 7, first, the side wall bodies 13L and 13U and the core 12 of the rigid core 10 are disassembled and removed from the rigid core 10. Next, the second segment 14 </ b> B and the first segment 14 </ b> A are sequentially moved inward in the tire radial direction and removed from the vulcanized tire 1. Thereby, the tire 1 shown in FIG. 1 can be manufactured.

  Then, in the inner liner forming step S11 of the present invention, as shown in FIG. 8, the rubber strip 24 formed in the tape shape shown in FIG. It is affixed in a spiral while overlapping each other. Thereby, as shown in FIG. 10A, the inner liner 9 is formed in which a plurality of overlapping portions 25 where the side edges 24t of the rubber strip 24 overlap are formed. Such an inner liner forming step S11 is useful for eliminating intermediate stock and increasing productivity.

  Further, as shown in FIG. 8, the inner liner 9 affixed to the outer surface 18 of the rigid core 10 includes a tread portion side region 9a affixed to the tread molding surface 18a of the rigid core 10, and a sidewall. A sidewall portion side region 9b attached to the molding surface 18b and a bead portion side region 9c attached to the bead molding surface 18c are included. The sidewall portion side region 9b is formed to protrude outward in the tire axial direction from the bead portion side region 9c.

  As described above, the sidewall molding surface 18b of the rigid core 10 projects outward in the tire axial direction from the bead molding surface 18c. For this reason, as shown in FIG. 7 and FIG. 10B, in the rigid core removing step S3, the bead portion 4 of the tire 1 becomes the sidewall by moving the segments 14A and 14B inward in the tire radial direction. The molding surface 18b is pushed outward in the tire axial direction. As a result, large friction is likely to occur between the bead portion side region 9 c of the inner liner 9 and the sidewall molding surface 18 b of the rigid core 10. Such large friction tends to cause the rubber strip 24 of the inner liner 9 to be peeled off, and easily lowers the detachability of the rigid core 10.

  Therefore, in the inner liner forming step S11 of the present embodiment, as shown in FIG. 8 and FIG. 10 (a), at least a pair of bead molding surfaces 18c and 18c among the outer surface 18 of the rigid core 10 is rubber. The strip 24 is spirally attached from the outside in the tire radial direction to the inside. As shown in FIG. 10B, in the bead portion side region 9c of the inner liner 9, the side edge 24t on the outer side in the tire radial direction of the rubber strip 24 is adjacent to the outer side in the tire radial direction. Covered by a strip 24.

  Thus, in the bead portion side region 9c of the inner liner 9, the side edges 24t on the outer side in the tire radial direction of the rubber strip 24 are moved to the outer surface 18 of the rigid core 10 by the movement of the segments 14A and 14B toward the inner side in the tire radial direction. Can be prevented from being overwhelmed. Therefore, in the manufacturing method of the present invention, the rubber strip 24 can be effectively prevented from being peeled off, and the detachability of the rigid core 10 can be improved. In addition, in this embodiment, for example, since it is not necessary to apply a release agent to the outer surface 18 of the rigid core 10, problems such as poor adhesion of the rubber strip 24 due to the release agent can be prevented.

  As shown in FIG. 8, the rubber strip 24 is formed on the outer surface 18 of the rigid core 10 in the region radially inward from the maximum width position 20 of the rigid core 10 and from the outer side in the tire radial direction to the inner side in the tire radial direction. It is desirable to be attached in a spiral shape. As a result, as shown in FIG. 10 (b), the rubber strip 24 can be more effectively prevented from being peeled off at the inner liner 9 in the portion that contacts the maximum width position 20 of the rigid core 10. Moreover, as shown in FIG. 8, in this embodiment, since the rubber strip 24 can be continuously pasted from the maximum width position 20 to the bead molding surface 18c, the durability of the inner liner 9 is further improved. be able to.

  Further, the rubber strip 24 is spirally attached from the outer side in the tire radial direction to the inner side in the tire radial direction in a region on the inner side in the tire radial direction from the equator 10c of the rigid core 10 on the outer surface 18 of the rigid core 10. Is desirable. Thereby, the inner liner 9 can reliably prevent the rubber strip 24 from peeling in a wide range in the tire radial direction. Moreover, in this embodiment, since the rubber strip 24 can be continuously pasted from the equator 10c of the rigid core 10 to the bead molding surface 18c, the durability of the inner liner 9 can be further improved.

  As shown in FIG. 9, the width W1 of the rubber strip 24 is desirably 5 to 25 mm. If the width W1 of the rubber strip 24 is less than 5 mm, the number of windings of the rubber strip 24 increases, and the productivity of the inner liner 9 may be reduced. On the other hand, even if the width W1 of the rubber strip 24 exceeds 25 mm, the accuracy of attaching the rubber strip 24 is lowered, and the productivity of the inner liner 9 may be lowered. From this point of view, the width W1 of the rubber strip 24 is more preferably 10 mm or more, and more preferably 20 mm or less.

  From the same viewpoint, the thickness T1 of the rubber strip 24 is preferably 1.5 mm or less, and preferably 0.3 mm or more.

  Furthermore, as shown in FIG. 10A, the width W2 of the overlapping portion 25 where the side edges 24t of the rubber strip 24 overlap is desirably 50% or less of the width W1 (shown in FIG. 9) of the rubber strip 24. When the width W2 of the overlapping portion 25 exceeds 50% of the width W1 of the rubber strip 24, the overlapping portions 25 and 25 adjacent in the tire radial direction overlap each other. Such overlapping of the overlapping portions 25 and 25 tends to be a starting point of damage to the inner liner 9 because the rubber thickness of the inner liner 9 is locally increased. Thereby, there exists a possibility that the removal property of the rigid core 10 cannot fully be improved. Conversely, even if the width W2 of the overlapping portion 25 is less than 10% of the width W1 of the rubber strip 24, the side edge 24t on the outer side in the tire radial direction of the rubber strip 24 may not be sufficiently covered. From such a viewpoint, the width W2 of the overlapping portion 25 is preferably 35% or less of the width W1 of the rubber strip 24, and preferably 15% or more.

  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 manufacturing method of the present invention, tires using rubber strips shown in Table 1 were manufactured, and the detachability of these rigid cores and the productivity of the inner liner were evaluated. For comparison, as shown in FIG. 11 (a), a tire having an inner liner formed by attaching a rubber strip spirally from the inner side to the outer side in the tire radial direction was similarly evaluated. The common specifications are as follows.
Tire size: 235/40 R19
Number of rigid core segments: 8 The test method is as follows.

<Removability of rigid core>
Multiple test tires were vulcanized, and in the rigid core removal process, the time required to remove the rigid core by moving the rigid core segments inwardly in the tire radial direction at different speeds (cycle time) ) Was measured. Further, after taking out the rigid core, it was visually confirmed whether or not the rubber strip was peeled off from the inner liner. And in each test tire, the shortest cycle time was calculated | required among the several cycle time in which peeling of the rubber strip did not generate | occur | produce, respectively. The smaller the value, the better the removability of the rigid core.

<Inner liner productivity>
The rubber strip shown in Table 1 was spirally attached to the outer surface of the rigid core, and the average time required to form the inner liner of each test tire was measured. The results were expressed as an index with the comparative example as 100. The smaller the value, the better.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the removal method of the rigid core could be improved in the manufacturing method of the example.

1 Pneumatic tire 1L Raw tire 10 Rigid core 24 Rubber strip

Claims (5)

A sidewall part is a method for manufacturing a pneumatic tire that protrudes outward in the tire axial direction from the bead part by core molding,
By connecting a plurality of segments in the tire circumferential direction, an outer surface that forms a lumen surface of the pneumatic tire is formed, and by moving each segment inward in the tire radial direction in order, the pneumatic tire is formed. A raw tire forming step of forming a raw tire by attaching a tire member to the outer surface of an assembling-type rigid core capable of taking out each segment from the tire;
The raw tire is put together with the rigid core into a vulcanization mold having a cavity for forming the outer surface of the raw tire, and the raw tire is vulcanized to obtain a vulcanized tire. Vulcanization process,
A rigid core removing step of removing the rigid core from the vulcanized tire by moving the segments from the vulcanized tire inward in the tire radial direction ,
In the raw tire forming step, a tape-shaped rubber strip is placed on each of a pair of bead forming surfaces for forming the bead portion of the outer surface of the rigid core, and the side edges thereof are overlapped with each other in the tire radial direction. A method for manufacturing a pneumatic tire, comprising: an inner liner forming step in which a bead portion side region of an inner liner is formed in a spiral shape from the outside to the inside in a tire radial direction.
  The rubber strip extends from the outer side in the tire radial direction while overlapping the side edges thereof at least in the region inside the tire radial direction from the maximum width position of the rigid core in the tire axial direction on the outer surface of the rigid core. The manufacturing method of the pneumatic tire of Claim 1 affixed on the inner side of a tire radial direction spirally.   The rubber strip is spirally formed from the outer side in the tire radial direction to the inner side in the tire radial direction while overlapping the side edges in a region radially inward from the equator of the rigid core in the outer surface of the rigid core. The manufacturing method of the pneumatic tire of Claim 1 or 2 affixed on.   The method for manufacturing a pneumatic tire according to any one of claims 1 to 3, wherein the rubber strip has a width of 5 to 25 mm and a thickness of 0.3 to 1.5 mm.   The method for manufacturing a pneumatic tire according to any one of claims 1 to 4, wherein an overlapping portion where the side edges of the rubber strip overlap each other is 50% or less of the width of the rubber strip.

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