Method and apparatus for manufacturing pneumatic tires

Abstract

To provide a method for manufacturing pneumatic tires and equipment for manufacturing pneumatic tires capable of reducing irregularities in a sealant layer formed on the tires.SOLUTION: A method of manufacturing a pneumatic tire includes applying a strip of sealant material discharged from a discharge port of a nozzle to the inner surface of a tire to form a sealant layer on the inner surface of the tire while rotating the nozzle facing the inner surface of the tire relatively to the axial center of the tire. The discharge port has a first side located in front of the nozzle in the direction of travel of the nozzle and a second side located behind the nozzle in the direction of travel of the nozzle. At least one of the first side and the second side has a neck protruding inside the discharge port.SELECTED DRAWING: Figure 5

Description

Technical Field

[0005] , , ,

[0004] , , , , , , ,

[0001] The present disclosure relates to a method and an apparatus for manufacturing a pneumatic tire.

Background Art

[0002] As a pneumatic tire having a puncture prevention function, a pneumatic tire provided with a sealant layer formed by applying a sealant material to the inner surface of the tire (also referred to as a sealant tire) is known. In the sealant tire, a through hole formed at the time of puncture is automatically blocked by the sealant material, preventing air leakage from the tire.

[0003] Patent Document 1 discloses applying a sealant material spirally to the inner surface of a tire. Patent Document 2 discloses pressing with a roller until the next sealant material adheres adjacent to a strip-shaped sealant material applied to the inner surface of the tire.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] This disclosure provides a method and apparatus for manufacturing a pneumatic tire that can reduce the unevenness of the sealant layer formed on the tire. [Means for solving the problem]

[0007] A method for manufacturing a pneumatic tire according to the present disclosure includes applying a strip-shaped sealant material discharged from the discharge port of a nozzle to the inner surface of a tire while rotating a nozzle directed toward the inner surface of the tire relative to the axis of the tire, thereby forming a sealant layer on the inner surface of the tire, wherein the discharge port has a first side located on the front side in the direction of travel of the nozzle and a second side located on the rear side in the direction of travel of the nozzle, and at least one of the first side and the second side has a constriction that protrudes inward from the discharge port. [Brief explanation of the drawing]

[0008] [Figure 1] A cross-sectional diagram of a tire along its meridian. [Figure 2] A diagram illustrating the configuration of a tire manufacturing apparatus for producing sealant tires by forming a sealant layer. [Figure 3] A side view showing the sealant application process. [Figure 4] A schematic plan view of the sealant layer to illustrate the application structure of the sealant material. [Figure 5] A side view and a bottom view of the nozzle of the first embodiment showing how the nozzle discharges sealant material. [Figure 6] A side view and a bottom view of the nozzle of the second embodiment showing how the nozzle discharges sealant material. [Figure 7](a) A diagram showing the shape of the sealant layer applied by the nozzle of Comparative Example 1. (b) A diagram showing the shape of the sealant layer applied by the nozzle of the second embodiment shown in Figure 6. (c) A diagram showing the shape of the sealant layer applied by the nozzle of the first embodiment shown in Figure 5. [Figure 8] (a) and (b) Diagrams showing the cross-sectional shape of the sealant material applied to the inner surface of a tire by the nozzle of the second embodiment. (c) Diagram showing the cross-sectional shape of the sealant material applied to the inner surface of a tire by the nozzle of the first embodiment. [Figure 9] A diagram showing the bottom view of the modified nozzle. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of this disclosure will be described with reference to the drawings.

[0010] The pneumatic tire of this embodiment is a sealant tire that has a sealant layer formed by applying a strip-shaped sealant material along the circumferential direction of the tire to the inner surface of the tire. The tire is a so-called tubeless tire and is used in a state in which it is filled with a gas such as air.

[0011] [First Embodiment] Figure 1 is a meridian cross-sectional view of a tire 1. The tire 1 comprises an annular tread 2 that contacts the road surface, a pair of left and right bead portions 3, 3 located inside the tire radial direction RD of the tread 2, and a pair of left and right sidewalls 4, 4 located between the tread 2 and the bead portions 3, 3. The tire 1 comprises a bead core 5 embedded in the bead portion 3, a carcass ply 6 extending toroidally between the left and right bead portions 3, 3, a belt 7 and tread rubber 8 provided on the outer circumference side of the carcass ply 6 in the tread 2, an inner liner 9 provided on the inner surface side of the carcass ply 6, and a sealant layer 10 provided on the inner surface side of the inner liner 9.

[0012] The sealant layer 10 is provided by being overlapped on the inner surface 1A of the tire 1, specifically, on the inner side of the inner liner 9. In this example, the sealant layer 10 is provided from one end to the other end in the tire axial direction AD on the inner surface 1A of the tread 2. Thus, the sealant layer 10 is preferably provided over the entire inner surface of the tread 2, may be provided only on the inner surface of the tread 2, or may be provided in a wider range including the inner surface of the tread 2. That is, the sealant layer 10 is preferably provided on the inner surface 1A of the tire 1 including the inner surface of the tread 2.

[0013] Here, the tire radial direction RD indicates a direction perpendicular to the tire rotation axis. The inside in the tire radial direction RD means a direction approaching the tire rotation axis, and the outside in the tire radial direction RD means a direction away from the tire rotation axis. The tire axial direction AD, also referred to as the tire width direction, is a direction parallel to the tire rotation axis. The tire circumferential direction CD (see FIG. 4) is a direction on the circumference centered on the tire rotation axis.

[0014] In the tire manufacturing method of the first embodiment, the sealant layer 10 is formed by continuously applying a strip-shaped sealant material 11 (see FIG. 4) along the tire circumferential direction CD while displacing it from one side to the other side in the tire axial direction AD on the inner surface 1A of the vulcanized tire 1, and the tire 1 provided with the sealant layer 10 is manufactured.

[0015] The method for manufacturing a vulcanized tire is not particularly limited, and a known method can be adopted. That is, a green tire (unvulcanized tire) is produced using tire constituent members such as the tread rubber 8 together with the bead core 5, the carcass ply 6, and the belt 7, and a vulcanized tire is obtained by vulcanizing and molding the obtained green tire. Then, after the vulcanization molding of the green tire, the sealant layer 10 is formed using the sealant material 11.

[0016] The sealing material 11 is not particularly limited, and known sealing materials can be used. Generally, an adhesive rubber material is used as the sealing material. Specifically, for example, a rubber composition containing butyl rubber and / or ethylene propylene diene rubber as rubber components, and blended with liquid rubber, plasticizer, filler, crosslinking agent (organic peroxide), crosslinking aid (vulcanization accelerator), etc. can be used, but it is not limited thereto. Examples of butyl rubber include halogenated butyl rubber such as brominated butyl rubber and chlorinated butyl rubber in addition to butyl rubber.

[0017] FIG. 2 is a configuration diagram of a tire manufacturing apparatus 20 for forming a sealant layer 10 to manufacture a sealant tire, showing the tire 1 cut. The tire manufacturing apparatus 20 includes a support device 30 for supporting the tire 1, a discharge machine 40 for discharging the sealing material 11, and a control unit (not shown) for controlling the formation operation of the sealant layer 10 by the support device 30 and the discharge machine 40.

[0018] In this example, the support device 30 includes an outer peripheral support portion 31 for supporting the outer periphery of the tire 1 with the tire rotation axis horizontal, and a drive device 32 for rotating the supported tire 1 around the tire rotation axis. However, it is not limited thereto. For example, the outer peripheral support portion may support the outer periphery of the tire with the tire rotation axis inclined with respect to the horizontal direction.

[0019] The discharge machine 40 includes a nozzle 41 for discharging the sealing material 11, a supply device 42 for supplying the sealing material 11 to the nozzle 41, and a moving device 43 for moving the nozzle 41.

[0020] The supply device 42 is a device for supplying the heated sealing material 11 to the nozzle 41 via a supply pipe 44, and can be configured using a constant volume pump such as a gear pump.

[0021] The nozzle 41 is a component that discharges the sealant material 11 supplied from the supply device 42, and as shown in Figure 3, the nozzle 41 has a discharge port 45 at its tip for discharging the sealant material 11. The nozzle 41 is a die (mouthpiece) that discharges the sealant material 11 into a predetermined cross-sectional shape, and the discharge port 45 is an opening formed in the nozzle 41.

[0022] In this example, the mobile device 43 is a multi-axis robot having at least three degrees of freedom, with a nozzle 41 attached to the tip of its arm 43A. The mobile device 43 positions the nozzle 41 inside the tire 1, with the nozzle's discharge port 45 facing downwards.

[0023] Figure 5 is a side view and a bottom view of the nozzle 41 showing how the nozzle 41 of the first embodiment discharges the sealant material 11. As shown in Figures 3 and 5, the moving device 43 moves the nozzle 41 inside the tire 1 with the discharge port 45, i.e., the bottom surface of the nozzle 41, facing the inner surface 1A of the tire. As shown in Figure 5, the discharge port 45 has a flattened shape in which the length H1 in the direction of travel TD of the nozzle 41 is shorter than the length W2 in the orthogonal direction DD which is perpendicular to the direction of travel TD of the nozzle 41. The discharge port 45 in this example is an opening based on an elongated trapezoidal shape. In this embodiment, the short side of the discharge port 45 coincides with the direction of travel TD, and the long side of the discharge port 45 which is perpendicular to the short side TD coincides with the orthogonal direction DD.

[0024] As shown in Figure 5, the discharge port 45 has a first side 51 located on the front side TD1 in the direction of travel of the nozzle 41, a second side 52 located on the rear side TD2 in the direction of travel of the nozzle 41, a third side 53 and a fourth side 54 located on both sides in the orthogonal direction DD perpendicular to the direction of travel of the nozzle 41, a first corner 55, a second corner 56, a third corner 57, and a fourth corner 58. The first side 51 is a side that has a constriction that protrudes inward from the discharge port 45 than the first straight line 51s (virtual straight line) connecting the first corner 55 and the second corner 56. The constriction narrows the opening thickness of the discharge port 45. In the example in Figure 5, the first side 51 is a single curve with a radius of curvature of 8.2 mm, but is not limited to this. The second side 52 is a side that has a constriction that protrudes inward from the discharge port 45 than the second straight line 52s (virtual straight line) connecting the third corner 57 and the fourth corner 58. The constriction narrows the opening thickness of the discharge port 45. In the example of Figure 5, the second side 52 is a single curve with a radius of curvature of 8.2 mm, but is not limited to this. The third side 53 is the third straight line 53s connecting the first corner 55 and the third corner 57. The fourth side 54 is the fourth straight line 54s connecting the second corner 56 and the fourth corner 58. In this embodiment, each of the corners 55, 56, 57, and 58 is bent, but they may also be slightly rounded. Thus, the discharge port 45 has a shape based on a quadrilateral including a trapezoid, and each side (first side 51, second side 52, third side 53, fourth side 54) does not bulge outwards from the discharge port 45. Therefore, swell (expansion) of the sealant material 11 can be suppressed.

[0025] As shown in the figure, in the orthogonal direction DD, the length W1 of the first side 51 is shorter than the length W2 of the second side 52. W1 is 4.0 mm and W2 is 9.0 mm. The length H1 of the discharge port 45 in the direction of travel TD is 3.28 mm. In this embodiment, the maximum length W2 of the discharge port 45 in the longitudinal direction DD is 9.0 mm, but is not particularly limited and may be, for example, 8 to 20 mm. The length H1 of the discharge port 45 in the short direction TD is also not particularly limited and may be, for example, 2 to 5 mm. Furthermore, it is preferable that the first corner portion 55 is located inside the orthogonal direction DD more than the third corner portion 57. It is preferable that the second corner portion 56 is located inside the orthogonal direction DD more than the fourth corner portion 58.

[0026] In the first embodiment, the distance D1 between the discharge port 45 and the inner surface 1A of the tire is set to be less than or equal to the dimension W2 in the longitudinal direction DD of the discharge port 45, and in this example, D1 is set to W2. As shown in Figure 3, the moving device 43 moves the nozzle 41 inside the tire 1 with the bottom surface of the discharge port 45, i.e., the nozzle 41, facing the inner surface 1A of the tire. This makes it easy to define the thickness of the sealant material 11 discharged from the discharge port 45 by the gap between the discharge port 45 and the inner surface 1A of the tire, regardless of the orientation of the discharge port 45 which rotates as described later, and a strip-shaped sealant material 11 with a thickness corresponding to the above distance D1 can be formed on the inner surface 1A of the tire.

[0027] When forming a sealant material 11 having a thickness corresponding to the above-mentioned distance D1 on the inner surface 1A of the tire, it is preferable to control the discharge amount from the nozzle 41 using, for example, a gear pump. More specifically, since the thickness of the sealant material 11 formed on the inner surface 1A of the tire corresponds to the above-mentioned distance D1, and the width of the sealant material 11 corresponds to the length W2 in the longitudinal direction DD of the discharge port 45, it is preferable to control the gear pump so that the product of "distance D1 (mm)", "length W2 (mm)", and "rotational speed of the inner surface 1A of the tire relative to the nozzle 41 (i.e., the relative speed between the two) (mm / second)" becomes the "discharge amount per unit time (mm3 / second)".

[0028] The nozzle 41 is moved in the tire axial direction AD and the tire radial direction RD by the moving device 43. The angle of the nozzle 41 with respect to the tire radial direction RD can also be changed by the moving device 43. As a result, the nozzle 41 can move in the tire axial direction AD while maintaining a constant distance D1 while positioning the discharge port 45 opposite the curved inner surface 1A of the tire tread 2.

[0029] The moving device 43 is equipped with a nozzle rotating device 46 for rotating the nozzle 41. The nozzle rotating device 46 is located at the tip of the arm 43A, and the nozzle 41 is attached to the arm 43A via the nozzle rotating device 46. The nozzle 41 is configured to rotate so that the discharge port 45 at its tip rotates when the nozzle 41 is rotated.

[0030] When manufacturing a tire 1 using the tire manufacturing apparatus 20, the vulcanized tire 1 is placed on the support device 30, and the nozzle 41 of the discharger 40 is moved into the tire 1 so that the discharge port 45 faces the inner surface 1A of the tire. In this example, since the sealant layer 10 is provided on the inner surface of the tread 2 from one end to the other in the tire axial direction AD, the nozzle 41 is positioned to face the inner surface 1A of the tire at that one end.

[0031] Next, the drive unit 32 rotates the tire 1, and while the nozzle 41 moves relative to it along the tire circumferential direction CD, the supply unit 42 supplies sealant material 11 to the nozzle 41, and the sealant material 11 is discharged from the discharge port 45 of the nozzle 41, applying a strip-shaped sealant material 11 to the inner surface 1A of the tire along the tire circumferential direction CD. More specifically, as shown in Figure 3, the strip-shaped sealant material 11 is formed on the inner surface 1A of the tire through the gap between the inner surface 1A of the tire and the bottom surface of the nozzle 41 facing it.

[0032] As the sealant material 11 is applied along the tire circumferential direction CD, the nozzle 41 is gradually moved in the tire axial direction AD by the moving device 43. As a result, the sealant material 11 discharged from the discharge port 45 is continuously applied along the tire circumferential direction CD while being displaced from one side to the other in the tire axial direction AD, and is bonded without gaps between adjacent sealant material 11, 11 in the tire axial direction AD, thereby forming a sealant layer 10.

[0033] In this case, the nozzle 41 may be moved at a constant speed in the tire axis direction AD to apply the strip-shaped sealant material 11 in a spiral pattern at a slight inclination relative to the tire circumferential direction CD (spiral application).

[0034] In a preferred embodiment, as shown in Figure 4, a strip-shaped sealant material 11 may be applied parallel to the tire circumferential direction CD. After each rotation, the sealant material may be applied at an angle to the tire circumferential direction CD so that a feed pitch corresponding to the width dimension of the sealant material 11 (approximately the same as the dimension W2 in the longitudinal direction DD of the discharge port 45) is applied in a predetermined region G of the tire circumferential direction CD, thereby creating a parallel application section 12 and an inclined application section 13. This application configuration is called step application.

[0035] In the example shown in Figure 4, one end 2A in the tire axial direction AD on the inner surface 1A of the tire tread 2 is designated as the left side, and the other end 2B as the right side. A strip-shaped sealant material 11 is applied in steps from one end 2A to the other end 2B. The application starts at one point CD in the tire circumferential direction on the one end 2A, forming the starting end 14 of the sealant material 11. From there, it is applied parallel to the tire circumferential direction CD to form the first parallel application section 12A. After applying around the entire circumference, the nozzle 41 is moved one pitch to the other side in the tire axial direction AD to form the first inclined application section 13A. Next, the second parallel application section 12B is formed, followed by the second inclined application section 13B, and this is repeated until the other end 2B is reached. Finally, the last parallel application section 12Y is formed at the other end 2B, and the application ends 15 of the sealant material 11 are formed at a position that coincides with the previous inclined application section 13X to terminate the application.

[0036] In Figure 4, the number of turns of the strip-shaped sealant material 11, i.e., the number of turns of the parallel coating section 12, is 7. However, the number of turns of the sealant material 11 can be appropriately set according to the coating width of the sealant material 11 and the width of the sealant layer 10. Although spiral coating and step coating have been described above, the method is not limited to these, and various coating methods can be employed.

[0037] [Second Embodiment] Figure 6 is a side view and a bottom view of the nozzle 41 showing how the nozzle 41 of the second embodiment discharges the sealant material 11. As shown in Figure 6, the discharge port 45 has a flattened shape in which the length H2 in the direction of travel TD of the nozzle 41 is shorter than the length W2 in the orthogonal direction DD which is perpendicular to the direction of travel TD of the nozzle 41. The discharge port 45 in this example is an opening based on a rectangular shape.

[0038] The first side 51 is a side that has a constriction that protrudes inward from the discharge port 45 beyond the first straight line 51s (virtual straight line) connecting the first corner 55 and the second corner 56. The constriction narrows the opening thickness of the discharge port 45. In the example of Figure 6, the first side 51 is a single curve and its radius of curvature is 8.2 mm, but it is not limited to this. The second side 52 is a side that has a constriction that protrudes inward from the discharge port 45 beyond the second straight line 52s (virtual straight line) connecting the third corner 57 and the fourth corner 58. The constriction narrows the opening thickness of the discharge port 45. In the example of Figure 6, the second side 52 is a single curve and its radius of curvature is 8.2 mm, but it is not limited to this. The third side 53 is the third straight line 53s connecting the first corner 55 and the third corner 57. The fourth side 54 is the fourth straight line 54s that connects the second corner 56 and the fourth corner 58. Thus, the discharge port 45 has a shape based on a quadrilateral including a trapezoid, and each side (first side 51, second side 52, third side 53, fourth side 54) does not bulge outwards from the discharge port 45. Therefore, swell (expansion) of the sealant material 11 can be suppressed.

[0039] As shown in the figure, in the orthogonal direction DD, the length of the first side 51 and the length of the second side 52 W2 are the same, and in both cases W2 = 9.0 mm.

[0040] [Results of Comparative Example 1] The nozzle of Comparative Example 1, although not shown in the figure, has a circular discharge opening with a diameter of 4.0 mm when viewed from below. Figure 7(a) is a schematic diagram showing the shape of the sealant layer 10 applied by the nozzle of Comparative Example 1. Because the discharge opening of the nozzle 41 of Comparative Example 1 is a circular shape that bulges outwards from the discharge opening, swell (expansion) occurs in the discharged sealant material. As a result, a circular uneven shape is formed on the surface of the sealant layer 10 formed on the inner surface 1A of the tire.

[0041] [Results of the second embodiment] Figure 7(b) is a schematic diagram showing the shape of the sealant layer 10 applied by the nozzle 41 of the second embodiment shown in Figure 6. As shown in Figure 6, constrictions are formed on the first side 51 and the second side 52 of the discharge port 45, so swell (expansion) is suppressed compared to a square-shaped discharge port without constrictions, and the cross-sectional shape of the sealant material immediately after discharge becomes close to a square. However, as shown in the side view of Figure 6, the sealant material 11 discharged from the discharge port 45 curves towards the rear side TD2 in the direction of travel TD, so the amount of sealant material passing through the outside of the corner R2 is greater than the amount of sealant material passing through the inside of the corner R1. The discharged sealant material 11 is held down by the bottom surface of the nozzle 41, and the excess sealant material 11 has no choice but to escape to the side. As a result, as shown in Figure 8(a), the excess sealant material on the inner surface 1A side of the tire escapes to the side. The ideal cross-sectional shape is a square, but the side of the sealant material 11 becomes a protruding shape. Next, as shown in Figure 8(b), if the sealant material 11 is discharged from the nozzle 41 at a position adjacent to the sealant material 11 formed on the inner surface 1A of the tire, the excess sealant material on the inner surface 1A side will escape to the side, and the escaped sealant material 11 will push up the adjacent sealant material 11, which is thought to make it easier for irregularities to occur in the sealant layer 10.

[0042] [Results of the first embodiment] Figure 7(c) is a schematic diagram showing the shape of the sealant layer 10 applied by the nozzle 41 of the first embodiment shown in Figure 5. As shown in Figure 5, since constrictions are formed on the first side 51 and the second side 52 of the discharge port 45, swell (expansion) is suppressed compared to a square-shaped discharge port without constrictions, and the cross-sectional shape of the sealant material immediately after discharge becomes closer to a square. As shown in the side view of Figure 5, since the sealant material 11 discharged from the discharge port 45 curves towards the rear side TD2 in the direction of travel TD, the amount of sealant material passing through the outside R2 of the corner is greater than the amount of sealant material passing through the inside R1 of the corner. Therefore, as shown in the bottom view of Figure 5, the length W1 of the first side 51 located at the front side TD1 in the direction of travel TD of the discharge port 45 is shorter than the length W2 of the second side 52 located at the rear side TD2 in the direction of travel TD of the discharge port 45. As a result, the amount of sealant material 11 discharged from the vicinity of the first side 51 can be suppressed to be greater than the amount of sealant material 11 discharged from the vicinity of the second side 52, thereby suppressing the generation of excess sealant material on the inner surface 1A side of the tire. The cross-sectional shape of the sealant material 11 can be made closer to the original preferred rectangle, as shown in Figure 8(c), and the unevenness of the sealant layer 10 can be reduced.

[0043] [Differentiation] (A) In the first embodiment, constrictions are formed on both the first side 51 and the second side 52, but as shown in Figure 9(a), constrictions may be formed on either the first side 51 or the second side 52. In the example of Figure 9(a), a constriction is formed on the first side 51 and the second side 52 is a second straight line 52s without a constriction, but the invention is not limited to this. For example, the first side 51 may be a first straight line 51s without a constriction and the second side 52 may have a constriction. The same applies to the second embodiment, in which a constriction may be formed on either the first side 51 or the second side 52.

[0044] (B) As shown in Figure 9(b), at least one of the third side 53 and the fourth side 54 may have a constriction that protrudes inward from the discharge port 45. In the example of Figure 9(b), both the third side 53 and the fourth side 54 have constrictions, but the example is not limited to this.

[0045] (C) The constriction in the above embodiment is a single curve (arc), but is not limited thereto. The side having a constriction may consist of multiple curves, multiple straight lines, or a combination of one or more straight lines and one or more curves.

[0046] [1] As described above, the method for manufacturing a pneumatic tire includes applying a strip-shaped sealant material 11 discharged from the discharge port 45 of the nozzle 41 to the inner surface 1A of the tire while rotating the nozzle 41 directed toward the inner surface 1A of the tire relative to the axis of the tire, thereby forming a sealant layer 10 on the inner surface 1A of the tire. The discharge port 45 has a first side 51 located on the front side TD1 in the direction of travel TD of the nozzle 41, and a second side 52 located on the rear side TD2 in the direction of travel TD of the nozzle 41, and at least one of the first side 51 and the second side 52 may have a constriction that protrudes inward from the discharge port 45.

[0047] The sealant material 11 discharged from near the first side 51 of the nozzle 41 becomes the portion of the sealant layer 10 formed on the inner surface 1A of the tire, and the sealant material 11 discharged from near the second side 52 of the nozzle 41 becomes the portion of the sealant layer 10 formed on the inner surface 1A of the tire, opposite to the inner surface 1A. The first side 51 and the second side 52 of the nozzle 41 correspond to both sides in the thickness direction of the sealant layer 10 formed on the inner surface 1A of the tire, respectively. Since at least one of the first side 51 and the second side 52 of the nozzle 41 has a constriction, the amount of excess sealant material 11 can be reduced, and the unevenness of the sealant layer can be reduced. The sealant layer needs to have a predetermined thickness to seal holes in the tire, and the thinnest recessed portion of the unevenness in the sealant layer is set to the predetermined thickness. If the unevenness of the sealant layer can be reduced, the sealant layer in the raised portions that do not contribute to the puncture prevention function can be reduced, thereby suppressing the increase in tire weight and, consequently, suppressing the deterioration of fuel efficiency caused by the increase in tire weight.

[0048] [2] In the method for manufacturing a pneumatic tire described in [1] above, the discharge port 45 has a first corner 55, a second corner 56, a third corner 57, a fourth corner 58, a third side 53, and a fourth side 54, the first side 51 is a first straight line 51s connecting the first corner 55 and the second corner 56, or a side that protrudes inward from the discharge port 45 beyond the first straight line 51s, and the second side 52 is a second straight line connecting the third corner 57 and the fourth corner 58 The third side 53 is a side that protrudes inward from the discharge port 45 beyond line 52s or the second straight line 52s, the third side 53 is a side that protrudes inward from the discharge port 45 beyond the third straight line 53s or the third straight line 53s connecting the first corner 55 and the third corner 57, and the fourth side 54 is a side that protrudes inward from the discharge port 45 beyond the fourth straight line 54s or the fourth straight line 54s connecting the second corner 56 and the fourth corner 58. Thus, the discharge port 45 has a shape based on a quadrilateral, including rectangles and trapezoids, and each side does not extend outwards from the discharge port 45. This suppresses swell of the sealant material 11 and reduces the formation of unevenness by excess sealant material.

[0049] [3] In the method for manufacturing a pneumatic tire described in [2] above, at least one of the third side 53 and the fourth side 54 may have a constriction that protrudes inward from the discharge port 45. Since it is possible to suppress the lateral swell (expansion) of the sealant material 11 discharged from the discharge port 45, it is possible to reduce the unevenness of the sealant layer 10 formed on the inner surface 1A of the tire.

[0050] [4] In the method for manufacturing a pneumatic tire described in any of [1] to [3] above, the discharge port 45 may have a flattened shape in which the length W2 of the nozzle 41 in the direction of travel TD is shorter than the length H1 of the orthogonal direction DD which is perpendicular to the direction of travel TD. This configuration is preferable because it facilitates the formation of a thin and wide sealant layer 10 on the inner surface 1A of the tire.

[0051] [5] In the method for manufacturing a pneumatic tire described in any of [1] to [4] above, the length W1 of the orthogonal direction DD perpendicular to the direction of travel TD of the first side 51 may be shorter than the length W2 of the orthogonal direction DD of the second side 52. The sealant material 11 discharged from the nozzle 41 curves as the nozzle 41 moves and forms on the inner surface 1A of the tire. The path R2 of the sealant material 11 discharged from near the first side 51 is more outward than the path R1 of the sealant material 11 discharged from near the second side 52. As a result, the amount of sealant material 11 discharged from near the first side 51 is greater than the amount discharged from near the second side 52. Consequently, the excess sealant material 11 that reaches the inner surface 1A of the tire escapes in the width direction (direction DD perpendicular to the nozzle 41) which is perpendicular to the thickness direction of the sealant layer 10, pushing up the already formed sealant material 11 and creating irregularities in the sealant layer 10. With the above configuration, the amount of sealant material 11 discharged from the vicinity of the first side 51 is suppressed to be greater than the amount of sealant material 11 discharged from the vicinity of the second side 52, thereby reducing the amount of excess sealant material 11 and suppressing the formation of irregularities in the sealant layer 10.

[0052] [6] The pneumatic tire manufacturing apparatus comprises a support device 30 for supporting a tire 1 and a nozzle 41 capable of discharging a strip-shaped sealant material 11 from a discharge port 45. The apparatus is configured to apply the strip-shaped sealant material 11 discharged from the discharge port 45 of the nozzle 41 to the inner surface 1A of the tire 1 while the nozzle 41 directed toward the inner surface 1A of the tire 1 is rotated relative to the axis of the tire 1. The discharge port 45 has a first side 51 located at the front side TD1 in the direction of travel TD of the nozzle 41 and a second side 52 located at the rear side TD2 in the direction of travel TD of the nozzle 41, and at least one of the first side 51 and the second side 52 may have a constriction that protrudes inward from the discharge port 45.

[0053] Although embodiments of this disclosure have been described above with reference to the drawings, it should be understood that the specific configurations are not limited to these embodiments. The scope of this disclosure is indicated not only by the description of the embodiments above but also by the claims, and further includes all modifications within the meaning and scope equivalent to the claims.

[0054] The structures adopted in each of the above embodiments can be adopted in any other embodiment. The specific configuration of each part is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of this disclosure.

[0055] For example, the execution order of operations, procedures, steps, and stages in the devices, systems, programs, and methods shown in the claims, specifications, and drawings can be implemented in any order, as long as the output of a previous process is not used in a later process. Even if the flow in the claims, specifications, and drawings is described using terms such as "first," "next," etc., for convenience, it does not mean that the execution must be in that order. [Explanation of Symbols]

[0056] 1...Tire, 1A...Inner surface, 10...Sealant layer, 11...Sealant material, 30...Support device, 41...Nozzle, 45...Discharge port, 51...First side, 51s...First straight line, 52...Second side, 52s...Second straight line, 53...Third side, 53s...Third straight line, 54...Fourth side, 54s...Fourth straight line, 55...First corner, 56...Second corner, 57...Third corner, 58...Fourth corner, TD...Direction of travel (short side), TD1...Front side in the direction of travel, TD2...Rear side in the direction of travel, DD...Orthogonal direction (long side).

Claims

1. The process involves applying a strip-shaped sealant material discharged from the nozzle's outlet to the inner surface of the tire while rotating a nozzle directed towards the inner surface of the tire relative to the tire's axis, thereby forming a sealant layer on the inner surface of the tire. Includes, The discharge port at the tip of the nozzle has a first side located on the front side in the direction of travel of the nozzle and a second side located on the rear side in the direction of travel of the nozzle. At least one of the first side and the second side has a constriction that protrudes inward from the discharge opening, The discharge port at the tip of the nozzle has a flattened shape in which the length in the direction of travel of the nozzle is shorter than the length in the orthogonal direction perpendicular to the direction of travel. The length of the first side in the orthogonal direction perpendicular to the direction of travel is shorter than the length of the second side in the orthogonal direction. A method for manufacturing a pneumatic tire, comprising controlling the position of the nozzle so that the sealant material discharged from the vicinity of the first side becomes part of the sealant layer on the inner surface side of the tire.

2. The discharge port has a first corner, a second corner, a third corner, a fourth corner, a third side, and a fourth side. The first side is a first straight line connecting the first corner and the second corner, or a side that protrudes inward from the discharge opening beyond the first straight line. The second side is a second straight line connecting the third corner and the fourth corner, or a side that protrudes inward from the discharge opening beyond the second straight line. The third side is a third straight line connecting the first corner and the third corner, or a side that protrudes inward from the discharge opening beyond the third straight line. The method for manufacturing a pneumatic tire according to claim 1, wherein the fourth side is a fourth straight line connecting the second corner and the fourth corner, or a side that protrudes inward from the discharge port beyond the fourth straight line.

3. The method for manufacturing a pneumatic tire according to claim 2, wherein at least one of the third side and the fourth side has a constriction that protrudes inward from the discharge port.

4. A support device for the tire, It comprises a nozzle capable of dispensing a strip-shaped sealant material from its outlet, The system is configured to apply a strip-shaped sealant material discharged from the nozzle's discharge port to the inner surface of the tire while rotating the nozzle, which is directed toward the inner surface of the tire, relative to the tire's axis. The discharge port at the tip of the nozzle has a first side located on the front side in the direction of travel of the nozzle and a second side located on the rear side in the direction of travel of the nozzle. At least one of the first side and the second side has a constriction that protrudes inward from the discharge opening, The discharge port at the tip of the nozzle has a flattened shape in which the length in the direction of travel of the nozzle is shorter than the length in the orthogonal direction perpendicular to the direction of travel. The length of the first side in the orthogonal direction perpendicular to the direction of travel is shorter than the length of the second side in the orthogonal direction. A pneumatic tire manufacturing apparatus that controls the orientation of the nozzle so that the sealant material discharged from the vicinity of the first side becomes part of the sealant layer formed on the inner surface of the tire.

Images