JP2012024996A - Bead set ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bead set ring 46 which can contribute to the enhancement of productivity without lowering the quality of an obtained tire.SOLUTION: The bead set ring 46 includes a main ring 48 and an auxiliary ring 50. The main ring 48 includes a socket 52 to which the auxiliary ring 50 is fitted and the flange 54 positioned outside the socket 52. When the auxiliary ring 50 is fitted to the socket 52, a part of the auxiliary ring 50 protrudes from the flange 54 to constituted a protrusion 62, to which the bead 22 of the tire is set. The width W0 of the protrusion 62 is made variable according to the length fitted to the socket 52 of the auxiliary ring 50. Preferably, in the bead set ring 46, the width W0 of the protrusion 62 can be adjusted by revolving the auxiliary ring 50 in a peripheral direction.

Description

  The present invention relates to a bead set ring. Specifically, the present invention relates to a method for manufacturing a pneumatic tire using the bead set ring.

  A pneumatic tire is configured by combining a number of members. The tire includes, for example, a pair of beads and a carcass bridged between the two beads.

  The bead includes a core and an apex that extends radially outward from the core. The core is formed by winding a non-stretchable wire (typically a steel wire). Apex is made of a crosslinked rubber. The carcass is composed of a carcass ply including a large number of cords arranged in parallel.

  In the tire manufacturing method, the apex is molded by extruding a rubber composition. This apex is combined with the core to obtain a ring-shaped bead. The bead is set on a bead set ring, which will be described later, and is crimped to the carcass ply. Components such as treads and sidewalls are further combined to obtain a raw cover. The raw cover is put into the mold. The raw cover is heated and pressurized in the mold to obtain a tire.

  FIG. 8 is a cross-sectional view showing a part of a conventional bead set ring 2. A bead 4 is set in the bead set ring 2.

  The bead set ring 2 includes a protrusion 8 and a flange 10. The protrusion 8 protrudes from the flange 10. The protrusion 8 has a ring shape. The bead 4 is fitted to the protrusion 8. The flange 10 extends radially outward from the protrusion 8. The flange 10 comes into contact with the core 12 of the bead 4 fitted to the protrusion 8. The flange 10 restrains the bead 4 from moving outward in the axial direction.

  FIG. 8 shows a part of the carcass ply 6 wound around the former F and formed into a cylindrical shape. The carcass ply 6 is bent at an end portion of the former F. The carcass ply 6 is located inside the bead set ring 2 in the axial direction. As shown, a part of the carcass ply 6 is located between the core 12 of the bead 4 and the former F.

  In the tire manufacturing apparatus, when the bead 4 is set on the bead set ring 2, the bead set ring 2 moves inward in the axial direction, and the bead 4 is pressed against the carcass ply 6. Examples of such a manufacturing apparatus are disclosed in Japanese Patent Laid-Open Nos. 3-243337 and 6-45725.

JP-A-3-243337 Japanese Utility Model Publication No. 6-45725

  Various tires are produced in the manufacturing apparatus. There are various specifications of the beads 4 supplied to the manufacturing apparatus. This manufacturing apparatus may be supplied with beads 4 having cores 12 having the same inner diameter but different widths.

  In FIG. 8, the double arrow WA is the width of the protrusion 8 of the bead set ring 2. A double-headed arrow WB is the axial width of the core 12 fitted into the protrusion 8.

  In this manufacturing method, a bead 4 having a core 12 having a width WB smaller than the width WA may be supplied and set on the bead set ring 2. In this case, there is a problem that the beads 4 are not sufficiently pressed against the carcass ply 6 and the quality is not stable.

  In this manufacturing method, the bead 4 having the core 12 having the width WB larger than the width WA may be supplied and set in the bead set ring 2 in some cases. In this case, there is a problem that the bead 4 fitted to the protrusion 8 falls and the quality and productivity are lowered.

  As shown in FIG. 8, the protrusion 8 and the flange 10 of the bead set ring 2 are formed integrally with the main body 14. The width WA of the protrusion 8 is unchanged. In this bead set ring 2, the width WA cannot be adjusted according to the width WB of the bead 4. For this reason, in this manufacturing method, it is necessary to prepare several types of bead set rings 2 having different widths WA. The maintenance of these bead set rings 2 requires a great deal of cost and labor. It takes time to properly use these bead set rings 2.

  In this manufacturing apparatus, when the width WB of the supplied beads 4 is changed, the bead set ring 2 needs to be replaced with another bead set ring 2 having a width WA corresponding to the width WB. During this exchange, production stops. This bead set ring 2 has a limit in improving productivity.

  An object of the present invention is to provide a bead set ring that can contribute to an improvement in productivity without deteriorating the quality of the obtained tire.

  The bead set ring according to the present invention includes a main ring and a sub ring. The main ring includes a socket into which the sub ring is fitted, and a flange located outside the socket. When the secondary ring is fitted into the socket, a part of the secondary ring protrudes from the flange, thereby forming a protrusion for setting the tire bead. The width of the protrusion can vary depending on the length of the sub-ring fitted into the socket.

  Preferably, in this bead set ring, the socket is provided with a female screw. A male screw corresponding to the female screw is provided in a portion of the sub-ring that is fitted into the socket. The width of the protrusion can be adjusted by rotating the sub-ring in the circumferential direction.

The tire manufacturing method according to the present invention includes:
(1) a step in which a bead having a ring-shaped core is obtained;
(2) A main ring and a sub ring are provided. The main ring includes a socket in which the sub ring is fitted and a flange located outside the socket. The sub ring is fitted in the socket. Then, a part of the sub-ring protrudes from the flange to form a protrusion on which the tire bead is set, and the width of the protrusion varies depending on the length of the sub-ring fitted into the socket. In the bead set ring, the width of the protrusion is adjusted, and the bead is set on the protrusion.
(3) a step in which this bead is pressure-bonded to the ply to obtain a raw cover;
(4) The raw cover is pressurized and heated to obtain a tire.

  In the bead set ring according to the present invention, the width of the protrusion can be changed in accordance with the width of the core of the supplied bead. According to this bead set ring, the bead can be securely and sufficiently pressed onto the carcass ply. This bead set ring can contribute to the improvement of tire productivity without deteriorating the quality of the obtained tire.

FIG. 1 is a cross-sectional view showing a part of a tire manufactured by a manufacturing method according to an embodiment of the present invention. FIG. 2 is a plan view showing a bead set ring used for manufacturing a tire. FIG. 3 is a front view illustrating the bead set ring of FIG. 2. FIG. 4 is an exploded front view of the bead set ring of FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. FIG. 6 is a cross-sectional view showing a state in which the secondary ring of the bead set ring is further screwed. FIG. 7 is a cross-sectional view showing a use state of the bead set ring. FIG. 8 is a cross-sectional view showing a part of a conventional bead set ring.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 shows a part of a tire 16 manufactured by a manufacturing method according to an embodiment of the present invention. The tire 16 has a substantially bilaterally symmetric shape with the one-dot chain line CL as the center. This alternate long and short dash line CL represents the equator plane of the tire 16. The tire 16 includes a tread 18, a sidewall 20, a bead 22, a carcass 24, a belt 26, a band 28, an inner liner 30 and a chafer 32. In FIG. 1, the vertical direction is the radial direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction.

  The tread 18 is made of a crosslinked rubber having excellent wear resistance. The tread 18 has a shape protruding outward in the radial direction. The outer surface of the tread 18 is a tread surface 34 that contacts the road surface.

  The sidewall 20 extends substantially inward in the radial direction from the end of the tread 18. The sidewall 20 is made of a crosslinked rubber.

  The bead 22 is located substantially inward of the sidewall 20 in the radial direction. The bead 22 includes a core 36 and an apex 38 that extends radially outward from the core 36. The core 36 has a ring shape. The core 36 is formed by winding a non-stretchable wire. The apex 38 is tapered outward in the radial direction. The apex 38 is made of a highly hard crosslinked rubber.

  The carcass 24 includes a carcass ply 40. The carcass ply 40 is stretched between the beads 22 on both sides, and extends along the inside of the tread 18 and the sidewall 20. The carcass ply 40 is folded around the core 36 from the inner side to the outer side in the axial direction.

  Although not shown, the carcass ply 40 is composed of a large number of cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each cord with respect to the equator plane is usually 70 ° to 90 °. In other words, the carcass 24 has a radial structure. The cord is usually made of organic fibers. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. A carcass having a bias structure may be employed.

  The belt 26 is located on the radially outer side of the carcass 24. The belt 26 is laminated with the carcass 24. The belt 26 includes an inner layer 42 and an outer layer 44. Although not shown, each of the inner layer 42 and the outer layer 44 is composed of a large number of cords arranged in parallel and a topping rubber. Each cord is inclined with respect to the equator plane. The absolute value of the tilt angle is not less than 10 ° and not more than 35 °. The cord inclination direction of the inner layer 42 is opposite to the cord inclination direction of the outer layer 44. A preferred material for the cord is steel. An organic fiber may be used for the cord.

  The band 28 covers the belt 26. Although not shown, the band 28 is composed of a cord and a topping rubber. The cord extends substantially in the circumferential direction and is wound spirally. The band 28 has a so-called jointless structure. The cord is usually made of organic fibers. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The inner liner 30 is joined to the inner peripheral surface of the carcass 24. The inner liner 30 is made of a crosslinked rubber. The inner liner 30 is made of rubber having excellent air shielding properties.

  In manufacturing the tire 16, a bead set ring 46 shown in FIGS. 2, 3, and 4 is used. In FIG. 2, the direction perpendicular to the paper surface is the axial direction. 3 and 4, the vertical direction is the axial direction. The bead set ring 46 includes a main ring 48 and a sub ring 50. The main ring 48 includes a socket 52 and a flange 54. The socket 52 and the flange 54 are located inside the main ring 48 in the axial direction. The socket 52 is a depression. The secondary ring 50 is fitted into the socket 52. The flange 54 is located outside the socket 52 in the radial direction. The flange 54 extends radially outward from the socket 52. As shown in FIG. 2, the flange 54 is provided with twelve holes 56 and three grooves 58. Of the twelve holes 56, the eight holes 56a are countersunk. These holes 56 are used for attachment to a manufacturing apparatus (not shown).

  The secondary ring 50 includes an adapter 60 on the outer side in the axial direction. The shape of the adapter 60 corresponds to the shape of the socket 52. When the secondary ring 50 is fitted into the socket 52, the adapter 60 is passed through the socket 52.

  FIG. 5 is a cross-sectional view taken along line VV in FIG. In FIG. 5, the horizontal direction is the axial direction, and the vertical direction is the radial direction. In FIG. 5, the direction indicated by the arrow A is axially outward.

  The bead set ring 46 is configured by combining a main ring 48 and a sub ring 50. As shown in the figure, in the bead set ring 46, a part of the secondary ring 50 protrudes from the flange 54 of the main ring 48. This protruding portion is the protrusion 62 of the bead set ring 46. In the bead set ring 46, the protrusion 62 is configured by fitting the sub ring 50 into the socket 52. In FIG. 5, what is indicated by a double-headed arrow W0 is the width of the protrusion 62. The width W0 is represented by the length from the tip 64 of the sub ring 50 to the flange 54.

  As shown in the figure, a female screw 66 is provided on the side surface of the socket 52. The adapter 60 of the sub ring 50 is provided with a male screw 68 corresponding to the female screw 66. In this bead set ring 46, the sub ring 50 is screwed into the socket 52 by fitting the adapter 60 into the socket 52 and rotating the sub ring 50 in the circumferential direction with respect to the main ring 48.

  FIG. 6 is a cross-sectional view showing a state in which the secondary ring 50 of the bead set ring 46 is further screwed. When the secondary ring 50 is screwed, the secondary ring 50 can move outward in the axial direction. By this movement, the length of the adapter 60 fitted into the socket 52 is gradually increased, and the width W0 of the protrusion 62 is gradually decreased. Then, as shown in FIG. 6, the secondary ring 50 contacts the bottom 70 of the socket 52. In this bead set ring 46, the width W 0 of the protrusion 62 is minimum when the secondary ring 50 is in contact with the bottom 70 of the socket 52.

  In the bead set ring 46, when the sub ring 50 is rotated in the direction opposite to the screwing direction, the sub ring 50 can move inward in the axial direction. By this movement, the length of the adapter 60 fitted in the socket 52 is gradually reduced, and the width W0 of the protrusion 62 is gradually increased. Thus, the secondary ring 50 can move in the axial direction with respect to the main ring 48. The width W <b> 0 of the protrusion 62 can be changed according to the length of the adapter 60 fitted into the socket 52. In this bead set ring 46, the width W0 of the protrusion 62 can be adjusted by rotating the auxiliary ring 50 in the circumferential direction.

  As described above, in the bead set ring 46, the male screw 68 of the secondary ring 50 corresponds to the female screw 66 of the main ring 48. For this reason, after the width W0 of the protrusion 62 is adjusted, the width W0 of the protrusion 62 is stably maintained unless the auxiliary ring 50 is rotated in the circumferential direction. In the bead set ring 46, the movement of the auxiliary ring 50 in the axial direction is effectively restrained.

  Using the bead set ring 46, the tire 16 is manufactured as follows. The rubber composition is extruded and the apex 38 is formed. The apex 38 is combined with the core 36 to obtain the bead 22. The bead 22 is set on the protrusion 62 of the bead set ring 46.

  FIG. 7 shows a bead set ring 46 in which the beads 22 are set. As shown in the figure, the core 36 of the bead 22 is fitted to the protrusion 62 of the bead set ring 46. In FIG. 7, what is indicated by a double arrow W1 is the axial width of the core 36. What is indicated by a point P is a position where the width W1 of the core 36 is halved.

  Although not shown, in this manufacturing method, the bead set ring 46 on which the bead 22 is set moves inward in the axial direction. By this movement, the bead 22 is wound around the former and is crimped to the cylindrical carcass ply 40. Components such as the tread 18 and the sidewall 20 are further combined to obtain a raw cover.

  The raw cover is put into the opened mold. When thrown, the bladder is shrinking inside the mold. After charging, the bladder is filled with gas. This filling causes the bladder to expand. When inflated, the bladder expands.

  As the bladder expands, the raw cover deforms. The mold is tightened and the internal pressure of the bladder is increased. The raw cover is pressed between the cavity surface of the mold and the bladder. The raw cover is heated by heat conduction from the bladder and the mold. The rubber composition of the raw cover flows by pressurization and heating. The rubber causes a crosslinking reaction by heating, and the tire 16 shown in FIG. 1 is obtained.

  In this bead set ring 46, the diameter of the outer peripheral surface 72 of the protrusion 62 is equal to the inner diameter of the core 36. For this reason, when the bead 22 is set on the bead set ring 46, the core 36 of the bead 22 comes into contact with the outer peripheral surface 72 of the protrusion 62. In the bead set ring 46, the bead 22 can be stably held. The bead 22 is pressure-bonded to the carcass ply 40 with the center of the core 36 and the center of the former aligned. The bead set ring 46 can contribute to the production of high-quality tires 16.

  As shown in FIG. 7, the core 36 of the bead 22 is in contact with the flange 54. The flange 54 can restrain the movement of the bead 22 in the axially outward direction. Since the position of the bead 22 in the axial direction is stably maintained, the bead 22 is securely crimped to the carcass ply 40. The bead set ring 46 can contribute to the production of high-quality tires 16.

  As described above, the bead set ring 46 is configured such that the width W0 of the protrusion 62 can be adjusted by the rotation of the sub ring 50. For this reason, in this manufacturing method, prior to the setting of the bead 22, the secondary ring 50 is rotated, and the width W0 of the protrusion 62 is adjusted to a width corresponding to the width W1 of the core 36 of the bead 22 to be supplied. . This adjustment is easy.

  In this manufacturing method, the width W0 of the protrusion 62 is adjusted so that the tip 64 of the protrusion 62 is positioned on the outer side in the axial direction from the position P at which the width W1 of the core 36 is halved. In other words, the width W0 is adjusted to be larger than half of the width W1. Since the bead 22 is set to the protrusion 62 whose width W0 is appropriately adjusted, the bead 22 can be prevented from dropping from the protrusion 62, and the bead 22 can be securely crimped to the carcass ply 40. In this manufacturing method, the high-quality tire 16 can be manufactured stably. From the viewpoint that the fall of the bead 22 can be effectively prevented, the width of the protrusion 62 is set so that the difference (W1−W0) between the width W1 of the core 36 and the width W0 of the protrusion 62 is 2.5 mm or less. It is preferable that W0 is adjusted.

  In this manufacturing method, the width W 0 of the protrusion 62 is adjusted to be smaller than the width W 1 of the core 36. Since the bead 22 is set on the protrusion 62 whose width W0 is appropriately adjusted, the bead 22 can be sufficiently crimped to the carcass ply 40. In this manufacturing method, the high-quality tire 16 can be manufactured stably. From the viewpoint that the bead 22 can be securely and sufficiently crimped to the carcass ply 40, the protrusion (W1-W0) between the width W1 of the core 36 and the width W0 of the protrusion 62 is 1.0 mm or more. The width W0 of the portion 62 is preferably adjusted.

  In this bead set ring 46, the width W0 of the protrusion 62 can be varied. Therefore, in this manufacturing method, a tire different from the tire 16 shown in FIG. 1 having a core having a different width W1 can be manufactured without replacing the bead set ring 46 with another bead set ring. In this manufacturing method, unlike the conventional manufacturing method, it is not necessary to prepare a plurality of bead set rings having different protrusion widths. The bead set ring 46 can contribute to an improvement in productivity.

  Since this bead set ring 46 can appropriately change the width W0 of the protrusion 62 in accordance with the width W1 of the core 36 of the bead 22, even if the width W1 of the core 36 of the supplied bead 22 is changed, The difference (W1−W0) between the width W1 of the core 36 and the width W0 of the protrusion 62 can be maintained in an appropriate range. The bead set ring 46 can contribute to the improvement of the productivity of the tire 16 without deteriorating the quality of the obtained tire 16.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
Tires were manufactured using the bead set rings shown in FIGS. In manufacturing the tire, a bead having a core having a width W1 of 6.8 mm was supplied. The width W0 of the protrusion of the bead set ring was adjusted to 4.8 mm. The difference between the width W1 and the width W0 (W1-W0) was 2.0 mm.

[Example 3]
In the bead set ring of Example 1, the sub-ring is rotated, the width W0 of the protrusion is adjusted to 5.6 mm, and the difference (W1−W0) is set to 1.2 mm. Tires were manufactured.

[Example 2]
While supplying a bead having a core whose width W1 is set to 5.5 mm, in the bead set ring of Example 1, the secondary ring is rotated, the width W0 of the protrusion is adjusted to 3.5 mm, and the difference ( A tire was manufactured in the same manner as in Example 1 except that W1-W0) was 2.0 mm.

[Example 4]
While supplying a bead having a core whose width W1 is 8.6 mm, in the bead set ring of Example 1, the secondary ring is rotated, the width W0 of the protrusion is adjusted to 6.6 mm, and the difference ( A tire was manufactured in the same manner as in Example 1 except that W1-W0) was 2.0 mm.

[Reference example]
A tire was manufactured using a conventional bead set ring having the configuration shown in FIG. 8 and having a protrusion WA of 5.0 mm. In manufacturing the tire, a bead having a core having a width WB of 6.8 mm was supplied. In this reference example, the difference between the width WB and the width WA (WB−WA) was 1.8 mm.

[Comparative Examples 1 and 2]
A tire was manufactured in the same manner as in the reference example except that the width WB and the difference (WB-WA) of the core of the bead supplied to the bead set ring were as shown in Table 1 below. In Comparative Examples 1 and 2, the bead set ring used in the reference example is used as it is.

[Bead drop occurrence rate]
The number of occurrences of bead dropping was investigated and the ratio of the number of occurrences to the total number of tires produced was obtained. The results are shown in Tables 1 and 2 below as the bead drop occurrence rate. Smaller numbers indicate better results.

[Code path]
A piece corresponding to the core of the bead was set on the bead set ring. This piece was molded using the trade name “MC Nylon” manufactured by Nippon Polypenco. The outer edge located on the inner side in the axial direction of this piece was marked with chalk, and this piece was wound around a former and pressed against a cylindrical carcass ply. By this crimping, the chalk was transferred to the carcass ply. This crimping was performed on both the left and right sides of the carcass ply. After crimping, the carcass ply was unfolded and the distance between the left and right chokes was measured. The distances at 16 locations along the circumferential direction were measured, and these standard deviations were obtained. In this specification, this standard deviation is referred to as a code path. This series of measurements was carried out five times, and the average value of the code path was determined. The results are shown in Tables 1 and 2 below. Smaller numbers indicate better results.

  As shown in Tables 1 and 2, the manufacturing method of the example has higher evaluation than the manufacturing method of the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The method described above can also be applied to the manufacture of various tires.

2, 46 ... Bead set ring 4, 22 ... Bead 6, 40 ... Carcass ply 8, 62 ... Projection 10, 54 ... Flange 12, 36 ... Core 16 ... Tire 24 ... Carcass 38 ... Apex 48 ... Main ring 50 ... Sub ring 52 ... Socket 60 ... Adapter 66 ... Female screw 68 ... Male screw

Claims (3)

It has a main ring and a sub ring,
The main ring includes a socket into which the sub ring is fitted, and a flange located outside the socket,
When this secondary ring is fitted into this socket, a part of this secondary ring protrudes from this flange, and a protrusion is set in which the tire bead is set,
A bead set ring in which the width of the protrusion can be changed according to the length of the sub ring fitted into the socket. The socket is provided with a female thread,
A male screw corresponding to the female screw is provided on the portion of the secondary ring fitted into the socket.
The bead set ring according to claim 1, wherein the width of the protrusion can be adjusted by rotating the sub-ring in the circumferential direction. A step of obtaining a bead having a ring-shaped core;
A main ring and a secondary ring, the main ring having a socket in which the secondary ring is fitted and a flange located outside the socket; when the secondary ring is fitted in the socket, A bead set ring in which a part of the secondary ring protrudes from the flange to form a protrusion in which the tire bead is set, and the width of the protrusion can be changed according to the length of the secondary ring fitted into the socket. In the step, the width of the protrusion is adjusted, and the bead is set on the protrusion.
The bead is pressure-bonded to the ply to obtain a raw cover;
A method of manufacturing a tire including a step of pressing and heating the raw cover to obtain a tire.

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