JP6457873B2 - Molding drum and method of manufacturing pneumatic tire using the same - Google Patents

Description

  The present invention relates to a molding drum with improved tire productivity and ride comfort performance and a method for manufacturing a pneumatic tire using the same.

  Conventionally, a pneumatic tire provided with a tread reinforcing layer that reinforces a tread portion and a tread rubber disposed outside the tread portion is known. As a method for producing such a tread reinforcing layer, for example, there is a method in which a ribbon-like belt-like ply is wound around the outer peripheral surface of a drum in a spiral manner. In such a manufacturing method, the belt-like ply is likely to collapse due to slippage between the belt-like ply and the outer peripheral surface of the drum, a winding error of the belt-like ply, or the like. For this reason, in the conventional manufacturing method, in order to suppress the above-mentioned slip and winding error, the side edges of the belt-like plies adjacent in the tire axial direction are overlapped or butted together.

  However, since the tread reinforcing layer formed in this way has high rigidity, there is a problem that riding comfort performance is likely to deteriorate.

  In the tread reinforcing layer formed as described above, the tread rubber material having a wide band shape is pressed against the tread reinforcing layer from the tire equator side toward the outside, and the forming drum and the tread reinforcing layer are separated from each other. At times (not shown), a force in the tire axial direction acts on the belt-like ply. For this reason, there has been a problem that the belt-like ply collapses at the time of stitching and at the time of separation, and the productivity tends to deteriorate.

Japanese Patent Laying-Open No. 2005-247017

  The present invention has been devised in view of the above circumstances, and based on improving the outer peripheral surface of the molding drum, the molding drum having improved tire productivity and ride comfort performance and the use thereof are used. The main purpose is to provide a method for manufacturing a pneumatic tire.

  The present invention is a forming drum for forming a tread reinforcing layer of a tire by spirally winding a ribbon-like belt-like ply around an outer peripheral surface, and the outer peripheral surface guides a winding position of the belt-like ply. A concave groove is provided in a spiral shape.

  In the molding drum according to the present invention, it is preferable that the outer peripheral surface includes a reference surface having an arc-shaped profile convex outward in the drum radial direction and the concave groove recessed from the reference surface.

  In the molding drum according to the present invention, it is desirable that the width of the concave groove is 1.0 to 1.1 times the width of the belt-like ply.

  In the molding drum according to the present invention, it is desirable that the depth of the concave groove is smaller than the thickness of the belt-like ply.

  In the molding drum according to the present invention, it is desirable that the depth of the concave groove is 0.5 to 0.8 times the thickness of the belt-like ply.

  The pneumatic tire manufacturing method according to the present invention includes a tread reinforcing layer in which a belt-like ply is spirally wound while being fitted into a concave groove provided on an outer peripheral surface of a forming drum according to any one of claims 1 to 5. Including the step of forming.

  The forming drum of the present invention is a drum for forming a tread reinforcing layer of a tire by spirally winding a ribbon-like belt-like ply around an outer peripheral surface. The outer peripheral surface of the molding drum is provided with a concave groove for guiding the winding position of the belt-like ply. Such a concave groove can fix the winding of the belt-like ply, so that it is possible to prevent the belt-like ply from collapsing when the belt-like ply is wound or when tread rubber is stitched. can do.

  Moreover, the concave groove is provided in a spiral shape. The tread reinforcing layer formed by such a concave groove has a formation region where the band-like ply is formed and a non-formation region which is sandwiched between the formation regions and where no band-like ply is formed. Such a non-formation region effectively reduces the rigidity of the tire, so that the riding comfort performance is improved. Further, since the pitch between the belt-like plies adjacent to each other in the tire axial direction can be made uniform, the ride performance and the material cost of the belt-like ply can be improved in a well-balanced manner. Therefore, in the method for manufacturing a pneumatic tire according to the present invention, the productivity and riding comfort performance of the tire are improved in a well-balanced manner.

It is an expanded view of the outer peripheral surface of the molding drum of one Embodiment of this invention. It is an expanded sectional view of the AA part of FIG. It is sectional drawing of the pneumatic tire manufactured using the molding drum of this invention. It is a perspective view which shows one Embodiment of a strip | belt-shaped ply. (A) is sectional drawing explaining a band formation process, (B) is sectional drawing explaining a tread rubber sticking process. It is an expanded view of the strip | belt-shaped ply of other embodiment. It is sectional drawing of the shaping | molding drum of a prior art example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of the outer peripheral surface 11a of the forming drum 11 of the present embodiment. The molding drum 11 is used, for example, to mold a tire constituent member before vulcanization. The vertical axis in FIG. 1 indicates the angle in the tire circumferential direction, and the horizontal axis indicates the tire axial direction. FIG. 2 is an enlarged cross-sectional view of the AA portion of the forming drum 11 of FIG.

  As shown in FIGS. 1 and 2, the outer peripheral surface 11 a of the forming drum 11 includes a reference surface 12 and a concave groove 13 that is recessed from the reference surface 12. In the present embodiment, the concave grooves 13 and the reference surface 12 are provided alternately in the tire axial direction.

  The reference surface 12 of the present embodiment has an arcuate profile 14 that protrudes outward in the drum radial direction. This profile 14 approximates the profile of the tread portion 2 (shown in FIG. 3) of the tire 1. Thereby, the outer surface 8a of the tread rubber 8 can be approximated to the profile of the tread portion 2. The profile 14 of the present embodiment is a profile of a motorcycle tire. In addition, the tire 1 manufactured using the molding drum 11 of the present invention is not limited to a motorcycle, and may be a tire 1 for a passenger car, for example.

  FIG. 3 is a cross-sectional view of the tire 1 for a motorcycle in a normal state in which the rim is assembled on a normal rim (not shown) and the normal internal pressure is filled and no load is applied. As shown in FIG. 3, the tire 1 for a motorcycle is such that the outer surface 2a between the tread ends 2t, 2t of the tread portion 2 can provide a sufficient contact area even when turning with a large camber angle. Curved and extended in a convex arc shape outward in the radial direction. The developed length of the outer surface 2a between the tread ends 2t and 2t is the tread developed width TW.

  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, “Standard Rim” for JATMA and “Design Rim” for TRA. For ETRTO, "Measuring Rim".

  The “regular internal pressure” is the air pressure defined by each standard for each tire in the standard system including the standard on which the tire is based. For example, “maximum air pressure” for JATMA, “table pressure for TRA” The maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, and “INFLATION PRESSURE” in the case of ETRTO. In this specification, when there is no notice in particular, the dimension of each part of the tire 1 is a value in a normal state.

  The tire 1 includes a carcass 6, a tread reinforcing layer 7, and a tread rubber 8. The carcass 6 extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4. The tread reinforcing layer 7 is disposed radially outside the carcass 6 and inside the tread portion 2. The tread rubber 8 is arranged on the outer side in the radial direction of the tread reinforcing layer 7 and has an outer surface 2 a of the tread portion 2. A drainage groove (not shown) may be appropriately provided on the outer surface 2a.

  In the present embodiment, the carcass 6 is constituted by a single carcass ply 6A. The carcass ply 6A includes a main body portion 6a that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 embedded in the bead portion 4, and a folded portion 6b that is connected to the main body portion 6a and folded back by the bead core 5. . A bead apex rubber Ba made of hard rubber is provided between the main body 6a and the folded portion 6b.

  The tread reinforcing layer 7 is composed of at least one ply. The tread reinforcing layer 7 of the present embodiment is formed of a band layer 9 composed of one band ply 9A. The band ply 9A is formed by winding a ribbon-like band-like ply 10 spirally in the tire circumferential direction.

  The maximum width Wt in which the tread reinforcing layer 7 is developed is preferably 75% to 90% of the tread developed width TW. As a result, the carcass 6 is effectively tightened to improve the high-speed stability performance and the steering stability performance in a well-balanced manner and maintain a high ride comfort performance.

  FIG. 4 is a perspective view of the belt-like ply 10. As shown in FIG. 4, the belt-like ply 10 is formed by, for example, covering a single reinforcing cord 21 made of steel with a topping rubber 22. The reinforcing cord 21 is desirably wound at an angle of 5 degrees or less, more preferably 1 degree or less with respect to the tire circumferential direction. As the reinforcing cord 21, a twisted cord is desirable.

  Although not particularly limited, the width Wa of the belt-like ply 10 is preferably about 1.0 to 5.0 mm, for example. The thickness t of the belt-like ply 10 is preferably about 0.8 to 2.0 mm, for example.

  As shown in FIG. 1 and FIG. 2, in this embodiment, the concave groove 13 is a rectangular shape including a bottom portion 15 extending in the tire axial direction and a pair of side portions 16 and 16 connecting the bottom portion 15 and the reference surface 12. Shape. Such a concave groove 13 guides the winding position of the belt-like ply 10. That is, the side portion 16 of the concave groove 13 can hold the end surface 10e of the belt-like ply 10 with its frictional force and fix the winding position of the belt-like ply 10. Thereby, the concave groove 13 can suppress the collapse of the belt-like ply 10 when the belt-like ply 10 is wound or when the tread rubber 8 is stitched. Thereby, productivity improves. The bottom portion 15 of the present embodiment extends parallel to the reference surface 12, that is, in an arc shape.

  The concave groove 13 extends spirally. The tread reinforcing layer 7 formed of the concave groove 13 includes a formation region 18 where the belt-like ply 10 is formed and a non-formation region 19 which is sandwiched between the formation regions 18 and 18 and where the belt-like ply 10 is not formed. Have. As a result, the rigidity of the tire 1 is effectively reduced, and riding comfort performance is improved.

  The concave groove 13 of the present embodiment is formed by one continuous in the tire circumferential direction. That is, the concave groove 13 has one end 13a and the other end 13b in the tire axial direction. Such a concave groove 13 can continuously arrange the belt-like ply 10 from the one end 13a to the other end 13b, so that an excessive decrease in rigidity of the tread reinforcing layer 7 can be suppressed. In addition, the shape of the ditch | groove 13 is not limited to such an aspect.

  As in the present embodiment, it is desirable that the end faces 10e, 10e on both sides of the belt-like ply 10 are fitted into the concave groove 13. Thereby, since the collapse of the belt-like ply 10 is further suppressed, the productivity is further improved.

  The width (length in the developing direction) W of the concave groove 13 is preferably 1.0 to 1.1 times the width Wa (shown in FIG. 4) of the belt-like ply 10. When the width W of the concave groove 13 is less than 1.0 times the width Wa of the belt-like ply 10, the end faces 10e and 10e on both sides of the belt-like ply 10 cannot be fitted into the concave groove 13, and the belt-like ply 10 is firmly There is a possibility that it cannot be fixed to. When the width W of the concave groove 13 exceeds 1.1 times the width Wa of the belt-like ply 10, the fixing force by the side portions 16 may be reduced, and the collapse of the belt-like ply 10 may not be suppressed.

  The width W of the groove 13 is preferably 40% to 90% of one pitch (length in the developing direction) P of the groove 13. When the width W of the concave groove 13 exceeds 90% of one pitch P of the concave groove 13, the rigidity of the tread reinforcing layer 7 cannot be reduced, and the ride comfort performance may not be improved. When the width W of the concave groove 13 is less than 40% of one pitch P of the concave groove 13, the rigidity of the tread reinforcing layer 7 becomes excessively small, and there is a concern that traveling performance such as steering stability and turning performance may be deteriorated.

  Further, the depth D of the concave groove 13 is preferably smaller than the thickness t of the belt-like ply 10. That is, when the depth D of the concave groove 13 is larger than the thickness t of the belt-like ply 10, the belt-like ply 10 and the tread rubber 8 cannot be firmly fixed. For this reason, when the tread reinforcing layer 7 is separated from the forming drum 11, the belt-like ply 10 and the tread rubber 8 cannot be smoothly separated, and the belt-like ply 10 may collapse. From such a viewpoint, the depth D of the concave groove 13 is more preferably 0.8 times or less the thickness t of the belt-like ply 10.

  When the depth D of the concave groove 13 is excessively smaller than the thickness t of the belt-like ply 10, the fixing force of the concave groove 13 becomes small, and when the belt-like ply 10 is wound or when the tread rubber 8 is stitched, There is a risk of roll-up. For this reason, the depth D of the concave groove 13 is preferably 0.5 times or more the thickness t of the belt-like ply 10.

  The angle θ formed between the bottom portion 15 and the side portion 16 is desirably 90 to 95 °. When the angle θ exceeds 95 °, the fixing force by the side portion 16 of the concave groove 13 becomes small, and there is a possibility that the winding collapse occurs at the time of stitching when the belt-like ply 10 is wound around the outer peripheral surface 11a. When the angle θ is less than 90 °, the belt-like ply 10 may not be smoothly fitted into the groove 13.

  5A and 5B conceptually show an example of a method for manufacturing the tread reinforcing layer 7 and the tread rubber 8 of the tire 1 of the present embodiment. As shown in FIG. 5, in the present embodiment, a manufacturing apparatus T including a forming drum 11 and an applicator 25 that supplies the belt-like ply 10 to the outer peripheral surface 11 a of the forming drum 11 is used. In addition, since other tire structural members, such as the carcass 6 and the bead apex rubber Ba, are formed by a well-known manufacturing method, the description is abbreviate | omitted.

  The molding drum 11 is rotatably supported by a base (not shown) having, for example, a power transmission device for rotating the outer peripheral surface 11a.

  In addition, the molding drum 11 is preferably formed from a plurality of deck segments divided in the circumferential direction as in the prior art, and is held so as to be able to reduce the diameter via a known diameter reducing means. For example, the tread reinforcing layer 7 and the tread rubber 8 are removed in the reduced diameter state of the forming drum 11.

  The applicator 25 is formed in a conveyor shape, for example, and has a delivery roller 26 on the downstream side thereof. The delivery roller 26 spirally winds the belt-like ply 10 around the outer peripheral surface 11 a of the forming drum 11. On the upstream side of the applicator 25, for example, a rubber extruder for continuously extruding the belt-like ply 10 is provided (not shown). Thereby, the belt-like ply 10 is continuously supplied. The applicator 25 is supported by, for example, a three-dimensional movement device (not shown) that can reciprocate in the axial direction and the radial direction with respect to the forming drum 11.

  The manufacturing method for manufacturing the tread reinforcing layer 7 and the tread rubber 8 according to the present embodiment includes the tread reinforcing layer forming step S1 for forming the band layer 9, and the tread rubber 8 disposed outside the band layer 9 as the band layer 9. A tread rubber attaching step S2 for integrally joining.

  As shown in FIG. 5A, in the tread reinforcing layer forming step S1, for example, one belt-like ply 10 is fitted into the groove 13 from one end 13a to the other end 13b of the groove 13 in the tire axial direction. Fasten at. Thereby, the band layer 9 is formed. At this time, in order to securely fix the belt-like ply 10, for example, a pressing roller (not shown) may be used. Further, in order to suppress wrinkles of the belt-like ply 10 and to accurately fit the belt-like ply 10 in the concave groove 13, the rotation speed of the forming drum 11 and the moving speed of the applicator 25 are controlled by a known control device. Is desirable.

  Next, as shown in FIG. 5 (B), in the tread rubber attaching step S2, for example, a wide band-like unvulcanized tread rubber material 20 is prepared. Next, the tread rubber material 20 is wound around the outer peripheral surface 11a of the molding drum 11 in a cylindrical shape (step S2a). Next, for example, using a stitcher (not shown) having a known roller, the tread rubber material 20 is pressed against the band layer 9 and rolled down (step S2b). Thereby, the band layer 9 and the tread rubber 8 are integrally joined. At this time, since the belt-like ply 10 is firmly fixed by the concave groove 13, the occurrence of the collapse of the belt-like ply 10 is suppressed.

  Next, the band layer 9 and the tread rubber 8 are removed from the molding drum 11 by being reduced in diameter by, for example, a diameter reducing device (not shown) of the molding drum 11. Also at this time, since the groove 13 is formed with the above-mentioned size, the belt-like ply 10 and the groove 13 are smoothly separated, and the occurrence of the collapse of the belt-like ply 10 is suppressed.

  FIG. 6 shows another embodiment of the belt-like ply 10. The belt-like ply 10 includes, for example, a first portion 10A wound from one end 13a of the groove 13 in the tire axial direction to an intermediate position 13c on the tire equator C, and from the intermediate position 13c of the groove 13 to the other end 13b in the tire axial direction. You may be comprised with the 2nd part 10B wound. Thereby, by using two applicators (not shown), the first portion 10A and the second portion 10B can be wound around the outer peripheral surface 11a at the same time, so that the productivity is further improved.

  As mentioned above, although the pneumatic tire of this invention and its manufacturing method were demonstrated in detail, this invention is changed and implemented in various aspects, without being limited to said specific embodiment.

Motorcycle tires of size 180 / 55R17 having the basic structure shown in FIG. 1 were prototyped based on the specifications shown in Table 1, and the productivity, running performance, and riding comfort performance of each sample tire were tested. The common specifications and test methods for each sample tire are as follows.
Maximum width of tread reinforcement layer Wt / TW: 84%
Number of belt-like ply reinforcement cords: 1 Material of belt-like ply reinforcement cords: Steel Band-ply width Wa: 4.2 mm
Strip ply thickness t: 1.0 mm

<Productivity>
Using the manufacturing apparatus T shown in FIG. 5, 100 sets including one set of tread rubber and a tread reinforcing layer for one tire were manufactured, and the number of sets in which the tread reinforcing layer had collapsed was confirmed. . The result is displayed as a real number. The number of sets in which the rolls are broken is 3 or less.

<Running performance and ride performance>
Each sample tire was manufactured using a tread reinforcement layer and a tread rubber that did not collapse the belt-like ply manufactured in the productivity test, and was mounted on the rear wheel of a motorcycle with a displacement of 750 cc under the following conditions. The test driver ran the vehicle on a dry asphalt road test course. At this time, the running performance related to the straight running stability, turning performance, traction, grip, and the like and the riding comfort performance were evaluated based on the test driver's sensuality. The results are displayed with a score of Example 1 being 100. The larger the value, the better. A commercially available tire (size: 120 / 70R17) was used for the front wheels. A numerical 10-point difference is when there is a significant performance change between them, and a 5-point difference is when there is a clear performance change between them. Differences of 3 points or less are differences that are difficult for passengers to notice. The test results are shown in Table 1.
Internal pressure (all wheels): 200 kPa

  As a result of the test, it was confirmed that the tires of the examples were comprehensively superior in productivity, running performance, and riding comfort performance as compared with the comparative examples. In addition, a test was performed using a belt-like ply in which the size of the belt-like ply was changed within a preferable range and a forming drum corresponding to the belt-like ply.

DESCRIPTION OF SYMBOLS 1 Tire 7 Tread reinforcement layer 10 Band-like ply 11 Molding drum 11a Outer peripheral surface 12 Reference surface 13 Concave groove

Claims (6)

A forming drum for forming a tread reinforcing layer of a tire by spirally winding a ribbon-like belt-like ply on an outer peripheral surface,
The outer peripheral surface is a forming drum in which a concave groove for guiding a winding position of the belt-like ply is spirally provided.   The forming drum according to claim 1, wherein the outer peripheral surface includes a reference surface having a circular arc-shaped profile that protrudes outward in the drum radial direction, and the concave groove that is recessed from the reference surface.   The forming drum according to claim 1 or 2, wherein a width of the concave groove is 1.0 to 1.1 times a width of the belt-like ply.   The forming drum according to any one of claims 1 to 3, wherein a depth of the concave groove is smaller than a thickness of the belt-like ply.   The forming drum according to claim 4, wherein a depth of the concave groove is 0.5 to 0.8 times a thickness of the belt-like ply. A pneumatic tire manufacturing method comprising:
It includes a step of forming a tread reinforcing layer by winding a belt-like ply in a spiral while being fitted in a concave groove provided on the outer peripheral surface of the forming drum according to any one of claims 1 to 5. A method of manufacturing a pneumatic tire.

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