JP7137448B2 - Method for manufacturing pneumatic tires - Google Patents

Description

The present invention relates to a method for manufacturing pneumatic tires.

In order to manufacture a pneumatic tire, a tire component including a carcass ply is wound around a first molding drum to form a carcass band, while a tire component including a belt and a tread rubber is wound around a second molding drum to form a tread. form the band. Next, the tread band is transferred to a green tire molding position located on the outer diameter side of the carcass band by a belt transfer, and the carcass band expands radially outward and is bonded to the inner peripheral portion of the tread band, thereby forming a green tire. Mold the tire.

A pneumatic tire is manufactured by removing the molded green tire from the green tire molding position by green transfer and finally vulcanizing the green tire in a tire vulcanizing mold.

The molding drum is divided into a plurality of drum sectors in the circumferential direction, and each drum sector is configured to be expandable and contractible in the radial direction. is wound (see Patent Documents 1 and 2, for example).

On the other hand, the belt transfer and the green transfer are divided into a plurality of gripping portions in the circumferential direction, and each gripping portion is configured to be expandable and contractible in the radial direction. A tread band or a tread portion of a green tire is gripped radially inward at the peripheral portion (see Patent Documents 3 and 4, for example).

WO2007/116502 JP 2012-035562 A JP 2005-153284 A JP 2016-078342

In a pneumatic tire manufactured in this way, RFV (Radial Force Variation) is measured as one of the characteristics related to uniformity in the circumferential direction. RFV expresses the dispersion of the reaction force in the radial direction that occurs between the pneumatic tire and the ground contact surface when the pneumatic tire is rotated with a constant load applied. If the RFV becomes excessively large, it causes vibrations and the like during running, so it is required to reduce the RFV.

An object of the present invention is to provide a pneumatic tire manufacturing method capable of reducing RFV.

The present inventor has focused on reducing RFV by suppressing bending and / or residual strain that occurs in the belt cord included in the belt when molding the green tire as one of the factors of RFV. perfected the invention.

Specifically, the tread band molded by the molding drum is positioned corresponding to the first portion supported by the drum sector and the gap between the circumferentially adjacent drum sectors and is supported by the drum sector. 2nd part which is not in a line alternately in the circumferential direction. That is, the molding drum supports the tread band intermittently in the circumferential direction from the radially inner side. Similarly, the belt transfer and the green transfer intermittently support the tread band and the green tire from the outer diameter side, respectively, in the circumferential direction.

As a result, the tread band and the tread portion of the green tire are likely to be formed in a substantially polygonal shape, and the belt cords included in the tread band are subject to bending and/or residual strain due to the substantially polygonal shape. impact can occur. This effect may manifest as RFV in the final manufactured pneumatic tire.

Accordingly, the present invention is conceived to reduce the bending and/or residual strain that can occur in belt cords during green tire molding, thereby reducing RFV. The present invention is based on such an idea.

The present invention
Forming a tread band by cylindrically winding a tire component including a belt and a tread rubber around the outer periphery of each drum sector divided in the circumferential direction of the forming drum,
transferring the tread band to a green tire molding position located on the outer diameter side of the cylindrical carcass band containing the carcass ply;
bulging the carcass band radially outward and bonding it to the inner peripheral portion of the tread band to form a green tire;
removing the molded green tire from the green tire molding position;
A method for manufacturing a pneumatic tire by vulcanizing and molding the removed green tire,
The number of divisions of the molding drum is 17 or 19 ,
The removal of the green tire is performed by gripping the green tire from the outside in the radial direction by the inner peripheral portions of the green gripping portions divided in the circumferential direction of the green transfer,
There is provided a method for manufacturing a pneumatic tire, wherein the number of divisions of the green transfer is 17 or 19 .

According to the present invention, the molding drum is divided in the circumferential direction into 17 or 19 drum sectors, so that the belt cords included in the tread band molded on the outer circumference have 17 or 19 bends per circumference. Alternatively, an influence such as residual strain may occur. As a result, vibrations can appear at frequencies of the 17th or 19th order relative to tire rotation.

Here, the 17th or 19th order for tire rotation is larger than the order up to the 15th order that is generally targeted in uniformity evaluation, and the 3rd order that can be generated from the generally prepared three types of pattern pitch It is also different from the 7th, 9th, and 11th orders resulting from the general division numbers of 7, 9, and 11 in so-called segmented mold type tire vulcanizing molds. Furthermore, the 17th and 19th orders are prime numbers, and cannot be any multiple of the order subject to uniformity evaluation, the order based on the pattern pitch, and the order based on the number of divisions of the tire vulcanization mold. .

Therefore, it is possible to prevent the vibration of the order caused by the number of divisions of the forming drum from resonating with the vibration of the order caused by other factors, so that the RFV can be easily improved. In particular, by setting the number of divisions of the forming drum to 17 or 19, which tends to affect the belt cord, the above effects of the present invention are effectively exhibited.

In addition , the order resulting from the division number of the green transfer can be made different from any of the order subject to uniformity evaluation, the order resulting from the pattern pitch, and the order resulting from the division number of the tire vulcanization mold. cannot be a multiple of these as well. Therefore, it is possible to prevent resonance between the vibration of the order caused by the number of divisions of the green transfer and the vibration of the order caused by other factors. By setting the number of divisions of the green transfer to 17 or 19, which is likely to affect the belt cords next to the molding drum, the above effects are exhibited more effectively.

Preferably, the transfer of the tread band is carried out by gripping the tread band from the outside in the radial direction by inner peripheral portions of belt gripping portions divided in the circumferential direction of the belt transfer,
The division number of the belt transfer is 17 or 19.

According to this configuration, the order resulting from the number of divisions of the belt transfer must be different from any of the order subject to uniformity evaluation, the order resulting from the pattern pitch, and the order resulting from the number of divisions of the tire vulcanization mold. and cannot be multiples of these. Therefore, it is possible to prevent resonance between the vibration of the order caused by the division number of the belt transfer and the vibration of the order caused by other factors. By setting the number of divisions of the belt transfer, which tends to affect the belt cords next to the green transfer drum, to 17 or 19, the above effects are exhibited even more effectively.

Further, preferably, the number of divisions of the forming drum is different from the number of divisions of the green transfer and/or the number of divisions of the belt transfer.

According to this configuration, it is possible to prevent resonance between the vibration caused by the division number of the molding drum and the vibration caused by the division number of the green transfer and/or the division number of the belt transfer. This can further improve RFV.

Further, preferably, the number of divisions of the molding drum is equal to at least one of the number of divisions of the green transfer and the number of divisions of the belt transfer,
The division positions in the circumferential direction of the molding drum are the same as the division positions in the at least one circumferential direction having the same number of divisions.

According to this configuration, at least one of the portion of the tread band (or the tread portion of the green tire) supported by the drum sector of the molding drum and the green transfer and the belt transfer having the same number of divisions as the molding drum. The part gripped by the gripping part matches. As a result, the portion pressed radially outward by the molding drum is pressed radially inward by the one gripping portion, so that they act to cancel each other out. As a result, the tread band wound in a substantially polygonal shape can be easily corrected into a perfect circle, and the RFV is improved.

Further, preferably, the green transfer and the belt transfer are circumferentially divided at predetermined angular pitches,
The dividing positions of the green transfer in the circumferential direction are set to be offset by half the predetermined angular pitch from the dividing positions of the belt transfer in the circumferential direction.

According to this configuration, of the tread band (or the tread portion of the green tire), the portion supported radially inwardly by the green gripping portion and the portion supported radially inwardly by the belt gripping portion are aligned. Therefore, the influence (concave shape) of the portion supported radially inwardly on the tread band does not remain excessively.

Further, the portion of the tread band supported by the green gripping portion and the portion supported by the belt gripping portion are circumferentially shifted by half a pitch. As a result, the portion that is not supported radially inward by one of the green gripping portion and the belt gripping portion is supported radially inwardly by the other, so that the tread band is evenly pressed radially inward along the circumferential direction. be. As a result, the tread band can be more easily approximated to a perfect circle, thereby further improving the RFV.

Further, preferably, vulcanization molding of the green tire is performed by a tire vulcanization mold,
The tire vulcanization mold is divided into 17 or 19 sections in the circumferential direction.

According to this configuration, the order resulting from the number of divisions of the tire vulcanizing mold is the order subject to uniformity evaluation, the order resulting from the pattern pitch, and the order resulting from the number of divisions of the tire vulcanizing mold. It can be different from either and cannot be a multiple of these. Therefore, it is possible to prevent resonance between the vibration in the order caused by the division number of the tire vulcanizing mold and the vibration in the order caused by other factors.

Preferably, the forming drum has the tread band formed on the outer peripheral portion of the drum sector, and a plurality of the drum sectors are arranged in an annular shape at intervals in the circumferential direction,
The interval is set to 27 mm or less.

According to this configuration, by appropriately setting the interval between the drum sectors, the tread band is suppressed from falling into the interval, so that deformation of the tread band is suppressed and a perfect circle can be easily maintained. If the interval between the drum sectors is more than 27 mm, the tread band will drop excessively between the drum sectors, which may lead to poor uniformity.

ADVANTAGE OF THE INVENTION According to this invention, bending and/or a residual strain which may arise in a belt cord at the time of green tire molding can be reduced, and RFV can be reduced by this.

FIG. 2 is a plan view showing a schematic configuration of green tire molding equipment. The figure which shows roughly the molding process of a green tire. Side view of the forming drum. Side view of the belt transfer. Side view of the green transfer. The top view of a tire vulcanization mold. The side view of the green transfer which concerns on a modification. The side view of the green transfer which concerns on a further modification.

FIG. 1 is a schematic diagram showing a molding facility 100 for green tires T. As shown in FIG. As shown in FIG. 1, a green tire T molding facility 100 includes first to fourth molding devices 10, 20, 30, and 40. As shown in FIG. Each of the first to fourth molding apparatuses 10, 20, 30, 40 has first to fourth molding drums D1 to D4 for molding in each process.

The first molding device 10 includes a first molding drum D1, and first and second molding machines 11 for spirally winding an inner liner 5 made of a rubber strip and a rubber chafer 6 around the outer peripheral portion of the first molding drum D1. 12, third and fourth molding machines 13 and 14 for winding the belt-shaped first and second carcass plies 4a and 4b, a first transport path 15 connecting these in order, and a first transport path 15 along the first transport path 15. It has a first conveying section 16 for conveying one molding drum D1 to the first to fourth molding machines 11 to 14 in order.

As shown in FIG. 2(a), in the first molding device 10, the inner liner 5, the rubber chafer 6, and the first and second carcass plies 4a and 4b are sequentially wound around the outer periphery of the first molding drum D1. Then, a cylindrical carcass band 51 is molded. As shown in FIG. 1, the carcass band 51 is held from the outer peripheral side by the transfer 19 of the transfer means C1, extracted from the first forming drum D1, and transferred to the subsequent second forming device 20. As shown in FIG.

The second molding device 20 has a second molding drum D2 and a pair of supports 21 and 22 that rotatably support the second molding drum D2 from both sides in the width direction of the drum. The supports 21 and 22 are provided with turn-up means (not shown) such as an air bladder and setting means (not shown) for the bead 3 (see FIG. 2). After holding the carcass band 51 on the second forming drum D2, the setting means sets the beads at predetermined positions on both sides of the carcass band 51. As shown in FIG. As shown in FIG. 2(b), both side portions of the carcass band 51 are folded radially outward and inward in the width direction of the drum so as to wrap the bead 3 by the bladder of the turn-up means.

As shown in FIG. 1, a cylindrical carcass band 51 (also referred to as a green case) having both sides folded back in the second molding device 20 is held from the outer peripheral side by the transfer 23 of the transfer means C2 and placed on the molding drum. It is extracted from D2 and transferred to the subsequent fourth molding device 40 .

The third molding device 30 includes a third molding drum D3, fifth and sixth molding machines 31 and 32 for winding first and second band-shaped belts 7a and 7b around the outer circumference of the third molding drum D3, and strip-shaped belts. a seventh molding machine 33 for spirally winding the reinforcing belt 8; , a third conveying path 36 that connects them in order, and a third conveying section 37 that conveys the third molding drum D3 along the third conveying path 36 to the fifth to ninth molding machines 31 to 35 in order. ing.

As shown in FIG. 2(c), in the third molding device 30, the first and second belts 7a and 7b, the reinforcing belt 8, the tread base 9a, and the tread cap 9b are attached to the outer periphery of the third molding drum D3. A cylindrical tread band 52 is formed by winding in order. As shown in FIG. 1, the tread band 52 is held from the outer peripheral portion by the belt transfer 70, extracted from the third molding drum D3, and transferred to the fourth molding device 40. As shown in FIG.

The fourth molding device 40 has a fourth molding drum D4. The fourth molding drum D4 has a pair of supports 41 and 42 that hold the carcass band 51 transported from the second molding device 20 at the pair of left and right beads 3 from the inner diameter side. The pair of supports 41 and 42 are provided so as to be able to approach and separate from each other in the axial direction of the drum. (not shown).

As shown in FIG. 2(d), the belt transfer 70 aligns the tread band 52 with the carcass band 51 supported by the fourth molding drum D4, and the green tire molding portion located on the outer peripheral side of this is aligned with the center of the carcass band 51. After being transported to the position, the inflation medium is supplied to the inside of the carcass band 51 while the pair of supports 41 and 42 are brought close to each other. As a result, as shown in FIG. 2(e), a combined body is formed in which the carcass band 51 bulges outward in a toroidal shape and is joined to the inner peripheral portion of the tread band 52. As shown in FIG.

Further, as shown in FIG. 1, the fourth molding device 40 is provided with tenth molding machines 43, 43 for extruding rubber strips forming the sidewalls 2 to both side portions of the assembly. . As shown in FIG. 2(f), rubber strips for the sidewalls 2 are extruded and supplied to both side portions of the assembly by the tenth forming machines 43, 43 to complete the green tire T. As shown in FIG.

Therefore, according to the method for manufacturing a pneumatic tire according to the present embodiment, the tire constituent members including the belt 7 and the tread rubber 9 are cylindrically wound around the third molding drum D3 to form the tread band 52, and the tread band 52 is transferred to a green tire molding position located on the outer diameter side of the cylindrical carcass band 51 including the carcass ply 4, and the carcass band 51 is expanded radially outward to form the inner peripheral portion of the tread band 52. A pneumatic tire is manufactured by molding the green tire T by bonding to the green tire T, removing the green tire T from the green tire molding position, and vulcanizing the removed green tire T.

The completed green tire T is removed from the green tire molding position by the green transfer 80 of the transfer means C3. The removed green tire T is vulcanized and molded in a tire vulcanizing mold 90 (see FIG. 6) to manufacture a pneumatic tire.

FIG. 3 is a side view of the tread band 52 molded on the outer peripheral portion of the third molding drum D3 as seen from the tire axial direction. As shown in FIG. 3, the third molding drum D3 has an outer peripheral portion around which tire components are wound, which is divided into a plurality of drum sectors 60 in the circumferential direction.

Each drum sector 60 can be protruded and retracted in the radial direction of the third forming drum D3 from a radially inner position indicated by a dashed line to a radially outer position indicated by a solid line by driving means (not shown). The third molding drum D3 is configured such that the outer diameter thereof can be expanded and contracted by moving each drum sector 60 in the radial direction.

A plurality of tire constituent members are wound over the outer peripheral portion 61 of each drum sector 60 at the protruding position where each drum sector 60 protrudes radially outward. The tread band 52 wound around the third forming drum D3 is positioned between the drum sector support portion 52a supported from the radially inner side by the outer peripheral portion 61 of the drum sector and the adjacent drum sector 60. The non-drum supporting portions 52b that are not supported by the drum are alternately arranged in the circumferential direction.

The drum-supported portion 52a extends in an arc along the outer peripheral portion 61 of the drum sector, while the non-drum-supported portion 52b extends linearly between adjacent drum sectors 60. As shown in FIG. Therefore, the tread band 52 wound on the third forming drum D3 is molded into a substantially polygonal shape so that arc-shaped drum-supported portions 52a and linear non-drum-supported portions 52b are alternately arranged in the circumferential direction. be.

From this state, the tread band 52 is gripped from the radially outer side by the belt transfer 70 (see FIG. 4), and each drum sector 60 retreats radially inward, thereby reducing the diameter of the third forming drum D3. , thereby being transferred to the belt transfer 70 from the third forming drum D3.

FIG. 4 is a side view of the belt transfer 70 as seen from the tire axial direction of the tread band 52 gripped therein. As shown in FIG. 4, the belt transfer 70 has an annular shape, and the inner peripheral portion that grips the tread band 52 from the outer diameter side is divided into a plurality of belt gripping portions 71 in the circumferential direction.

Each belt gripping portion 71 is configured to project and retract in the radial direction of the belt transfer 70 from a radially outer position indicated by a dashed line to a radially inner position indicated by a solid line by driving means (not shown). The belt transfer 70 is configured such that the inner diameter thereof can be expanded and contracted by moving the belt gripping portions 71 in the radial direction.

At the protruded position where each belt gripping portion 71 protrudes radially inward, the inner peripheral portion 72 of each belt gripping portion 71 grips the tread band 52 from the radially outer side. The tread band 52 gripped by the belt transfer 70 is positioned between the belt gripping portion 52c gripped from the radially outer side by the inner peripheral portion 72 of the belt gripping portion 71 and the adjacent belt gripping portions 71, and is positioned between the belt gripping portions 71. The non-belt gripping portions 52d that are not gripped by the portion 71 are alternately arranged in the circumferential direction.

The belt gripped portion 52c extends arcuately along the inner peripheral portion 72 of the belt gripping portion 71, while the non-belt gripping portion 52d extends linearly between adjacent belt gripping portions 71. As shown in FIG. Therefore, the tread band 52 gripped by the belt transfer 70 is formed into a substantially polygonal shape in which arcuate belt gripped portions 52c and linear non-belt gripped portions 52d are alternately arranged in the circumferential direction.

FIG. 5 is a side view of the green transfer 80 viewed from the tire axial direction of the green tire T gripped here. As shown in FIG. 5, the green transfer 80 has an annular shape, and the inner peripheral portion that grips the green tire T from the outer diameter side is divided into a plurality of green gripping portions 81 in the circumferential direction.

Each green gripping portion 81 is configured to be protruded and retracted in the radial direction of the green transfer 80 from a radially outer position indicated by a dashed line to a radially inner position indicated by a solid line by driving means (not shown). The inner diameter of the green transfer 80 can be expanded and contracted by moving the green gripping portions 81 in the radial direction.

At the protruded position where each green gripping portion 81 protrudes radially inward, the inner peripheral portion 82 of each green gripping portion 81 grips the green tire T from the radially outer side. The green tire T gripped by the green transfer 80 is located between the green gripped portion Ta gripped from the radially outer side by the inner peripheral portion 82 of the green gripping portion 81 and the adjacent green gripping portion 81 and is gripped by the green. Non-green gripped portions Tb that are not gripped by the portion 81 are alternately arranged in the circumferential direction.

The green gripped portion Ta extends arcuately along the inner peripheral portion 82 of the green gripping portion 81 , while the non-green gripping portion Tb extends linearly between adjacent green gripping portions 81 . Therefore, the green tire T gripped by the green transfer 80 is molded into a substantially polygonal shape so that arc-shaped green-gripped portions Ta and linear non-green-gripped portions Tb are alternately arranged in the circumferential direction.

Here, the division number N1 of the third molding drum D3, the division number N2 of the belt transfer 70, and the division number N3 of the green transfer 80 are each set to a prime number of 17 or more. As shown in FIGS. 3 to 5, the numbers of divisions N1 to N3 are each set to 17 in this embodiment. As the number of divisions N1 to N3 increases, the number of parts of the third molding drum D3, the belt transfer 70, and the green transfer 80 increases and the structure becomes complicated. .

In addition, the third forming drum D3, the belt transfer 70, and the green transfer 80 are divided in the circumferential direction at the same angular position (same phase) about the tire axis of the tread band 52. As shown in FIG. That is, each drum sector 60 of the third molding drum D3, each belt gripping portion 71 of the belt transfer 70, and each green gripping portion 81 of the green transfer 80 are in the same phase around the tire axis of the tread band 52, They face each other with the tread band 52 interposed therebetween.

In other words, the drum supported portion 52a and the belt gripped portion 52c of the tread band 52 are positioned in the same phase and opposed to each other in the radial direction. Similarly, the drum-supporting portion 52a of the tread band 52 and the green-gripping portion Ta of the green tire T are located in the same phase and opposed to each other in the radial direction.

As a result, as indicated by white arrows in FIGS. 3 to 5, the drum-supported portion 52a of the tread band 52, which is supported from the radially inner side of the third forming drum D3 and pressed radially outward, The belt transfer 70 grips from the outside in the radial direction and presses toward the inside. Further, the drum supported portion 52a of the tread band 52 is gripped from the radially outer side by the green transfer 80 at the corresponding portion of the green tire T and pressed radially inward.

As a result, the tread band 52 supported in a substantially polygonal shape by the third molding drum D3 is gripped by the belt transfer 70 and the green transfer 80 and corrected to approximate a perfect circle.

Each of the drum sectors 60 is arranged in an annular shape with a space therebetween in the circumferential direction while being positioned at the projecting position. In FIG. 3, as shown by taking the third molding drum D3 as an example, the interval L between adjacent drum sectors 60 in the circumferential direction is set to 27 mm or less. With respect to each belt gripping portion 71 and each green gripping portion 81, each adjacent belt gripping portion 71 (or green gripping portion 81) with respect to the length of the inner peripheral portion 72 (or inner peripheral portion 82) is located at the projecting position. ) are similarly set.

As a result, excessive gaps are prevented from being formed between the elements divided in the circumferential direction, and the tread band 52 or the green tire T is prevented from falling into the gaps. Thereby, deformation of the tread band 52 or the green tire T can be easily suppressed.

According to the green tire molding facility described above, the following effects can be obtained.

(1) Since the third molding drum D3 is divided into 17 drum sectors 60 in the circumferential direction, the belt cord included in the tread band 52 molded on the outer peripheral portion is bent or bent at 17 points per circumference. Effects such as residual strain may occur. As a result, vibrations can appear at frequencies of the 17th order per tire revolution.

Here, the 17th order for tire rotation is larger than the order up to the 15th order that is generally targeted in uniformity evaluation, and is different from the 3rd order that can be generated from generally prepared three types of pattern pitches. It is also different from the 7th, 9th, and 11th orders resulting from the general division numbers of 7, 9, and 11 in segmented mold type tire vulcanizing molds. Furthermore, the 17th and 19th orders are prime numbers, and cannot be any multiple of the order subject to uniformity evaluation, the order based on the pattern pitch, and the order based on the number of divisions of the tire vulcanization mold. .

Therefore, the vibration in the order caused by the division number N1 of the third molding drum D3 can be prevented from resonating with the vibration in the order caused by other factors, so that the RFV can be easily improved. In particular, the RFV can be effectively reduced by setting the number of divisions of the third forming drum D3, which is likely to affect the belt cord, to be a prime number of 17 or more.

(2) By similarly setting the division numbers N2 and N3 of the belt transfer 70 and the green transfer 80 to 17, the resonance between the vibrations in the orders caused by these division numbers and the vibrations in orders based on other factors is eliminated. can be prevented.

(3) The division number N1 of the third molding drum D3, the division number N2 of the belt transfer 70, and the division number N3 of the green transfer 80 are equal to 17, and the respective division positions are set at the same angular position (phase). It is

In this case, as indicated by white arrows in FIGS. 3 to 5, the tread band 52 is supported by the drum sectors 60 of the third forming drum D3 from the radially inner side and pressed radially outward. The portion 52a and the belt gripping portion 52c supported from the outside in the radial direction by the belt gripping portions 71 of the belt transfer 70 and pressed toward the inner diameter side cancel each other. As a result, the tread band 52, which has been molded into a substantially polygonal shape on the third molding drum D3, is corrected so as to approach a perfect circle, thereby improving the RFV.

Similarly, the green gripping portion 81 of the green transfer 80 corrects the green tire T having the tread band 52 molded in a substantially polygonal shape on the third molding drum D3 so as to approach a perfect circle, thereby improving the RFV. do.

(4) As shown in FIG. 3, in the third forming drum D3, the interval L between adjacent drum sectors 60 positioned at the projecting positions is set to 27 mm or less. As a result, formation of excessive gaps between drum sectors divided in the circumferential direction is suppressed, and tread band 52 is suppressed from dropping into the gaps. As a result, the deformation of the tread band 52 is suppressed and it is easy to maintain the perfect circular shape. The belt transfer 70 and the green transfer 80 are also configured in the same manner, thereby suppressing the tread band 52 and the green tire T from falling between adjacent elements, thereby suppressing deformation.

If the interval L is larger than 27 mm, the tread band 52 will drop excessively between the drum sectors 60, which may lead to poor uniformity.

In the above embodiment, the number of divisions N1 to N3 of the third molding drum D3, the belt transfer 70, and the green transfer 80 is set to 17 for the green tire molding facility 100. In addition, the tire vulcanization metal Similarly, the division number N4 of the pattern 90 may be set to a prime number of 17 or more.

FIG. 6 is a plan view of the tire vulcanization mold 90. FIG. The tire vulcanization mold 90 is a segmented mold, and has a plurality of sectors 91 divided in the circumferential direction. Only each sector 91 is shown in FIG. Each sector 91 is configured to be radially projectable and retractable.

With the green tire T placed inside the tire vulcanization mold 90, each sector 91 protrudes radially inward to form a cavity 92 continuously formed in a perfect circle. is vulcanized to form a pneumatic tire. The division number N4 of the sector 91 is set to a prime number of 17 or more, like the division numbers N1 to N3 of the third molding drum D3, the belt transfer 70, and the green transfer 80 in the molding equipment 100. FIG. The upper limit of the division number N4 is similarly set to 19.

In the tire vulcanization mold 90, a cavity 92 formed by a plurality of sectors 91 is formed slightly larger than the outer diameter of the green tire T. As shown in FIG. Therefore, when the green tire T is molded to a predetermined standard size, the sector 91 does not normally come into contact with the green tire T when the mold is clamped to protrude radially inward.

However, when the green tire T is molded to have a large outer diameter exceeding the standard, the sector 91 protruding radially inward and the green tire T may come into contact with each other. In this case, in the green tire T, the elongation allowance during vulcanization molding differs between the portion that first contacts the sector 91 and the portion that contacts after mold clamping.

As described above, the tire vulcanization mold 90 has a prime number of divisions of 17 or more (17 in the present embodiment). Influences such as cord bending or residual strain are likely to occur. As noted above, the 17th order for tire rotation does not match orders based on other factors, nor does it match multiples of these. Therefore, it is possible to prevent resonance between the vibration in the order caused by the division number N4 of the tire vulcanization mold 90 and the vibration in the order based on other factors.

Further, in the above embodiment, the number of divisions N1 to N3 of the third molding drum D3, the belt transfer 70, and the green transfer 80 is set to be the same for the green tire T molding equipment 100, but may be different. For example, the division number N3 of the green transfer 83 may be set to 19 as shown in FIG.

In this case, since the order of vibration of the third molding drum D3 and the belt transfer 70 due to the division numbers N1 and N2 does not match the vibration order of the green transfer 80 due to the division number N3, their resonance is suppressed. RFV can be improved.

Further, in the above-described embodiment, the third molding drum D3, the belt transfer 70, and the green transfer 80 of the molding equipment 100 for the green tire T have the same number of divisions N1 to N3, and the division positions are also set to be the same. However, it is not limited to this. For example, as shown in FIG. 8, the division number N3 of the green transfer 85 may be kept at 17, and the dividing positions divided by the predetermined angular pitch may be shifted by half the predetermined angular pitch.

As a result, the belt gripping portion 52c of the tread band 52 and the green gripping portion Ta corresponding to the green tire T are not arranged in the same phase, so that the portion supported by the tread band 52 radially inward is not aligned. The influence (concavity) does not remain excessively.

Further, the belt gripping portion 52c of the tread band 52 and the corresponding green gripping portion Ta of the green tire T are shifted by half a pitch in the circumferential direction. As a result, in the green tire T and the tread band 52, the portion that is not supported radially inward by one of the green gripped portion Ta and the belt gripped portion 52c is supported radially inward by the other. 52 are evenly pressed radially inward along the circumferential direction. As a result, it is easy to correct the tread band 52 into a perfect circle, and the RFV is further improved.

The present invention is not limited to the configurations described in the above embodiments, and various modifications are possible.

7 belt 10 first molding device 20 second molding device 30 third molding device 40 fourth molding device 51 carcass band 52 tread band 52a supported drum portion 52b non-drum supported portion 52c belt gripped portion 52d non-belt gripped portion 60 drum Sector 70 Belt transfer 71 Belt gripping portion 80 Green transfer 81 Green gripping portion 90 Tire vulcanization mold 91 Sector D1 to D4 First to fourth molding drums T Green tire Ta Green gripping portion Tb Non-green gripping portion

Claims (8)

Forming a tread band by cylindrically winding a tire component including a belt and a tread rubber around the outer periphery of each drum sector divided in the circumferential direction of the forming drum,
transferring the tread band to a green tire molding position located on the outer diameter side of the cylindrical carcass band containing the carcass ply;
bulging the carcass band radially outward and bonding it to the inner peripheral portion of the tread band to form a green tire;
removing the molded green tire from the green tire molding position;
A method for manufacturing a pneumatic tire by vulcanizing and molding the removed green tire,
The number of divisions of the molding drum is 17 or 19 ,
The removal of the green tire is performed by gripping the green tire from the outside in the radial direction by the inner peripheral portions of the green gripping portions divided in the circumferential direction of the green transfer,
The method for manufacturing a pneumatic tire, wherein the number of divisions of the green transfer is 17 or 19 . The transfer of the tread band is carried out by gripping the tread band from the outside in the radial direction by inner peripheral portions of belt gripping portions divided in the circumferential direction of the belt transfer,
The division number of the belt transfer is 17 or 19,
The manufacturing method of the pneumatic tire according to claim 1 . The number of divisions of the molding drum is different from the number of divisions of the green transfer and/or the number of divisions of the belt transfer.
The manufacturing method of the pneumatic tire according to claim 2 . The number of divisions of the molding drum is equal to at least one of the number of divisions of the green transfer and the number of divisions of the belt transfer,
The division positions in the circumferential direction of the molding drum are the same as the division positions in the at least one circumferential direction having the same number of divisions.
The manufacturing method of the pneumatic tire according to claim 2 . The green transfer and the belt transfer are circumferentially divided at predetermined angular pitches,
The dividing position in the circumferential direction of the green transfer is set by shifting the dividing position in the circumferential direction of the belt transfer by half the predetermined angular pitch.
A method for manufacturing a pneumatic tire according to any one of claims 2 to 4 . Vulcanization molding of the green tire is performed by a tire vulcanization mold,
The tire vulcanization mold is divided into 17 or 19 in the circumferential direction,
A method for manufacturing a pneumatic tire according to any one of claims 1 to 5 . The forming drum has the tread band formed on the outer peripheral portion of the drum sector, and a plurality of the drum sectors are annularly arranged with intervals in the circumferential direction,
The interval is set to 27 mm or less,
A method for manufacturing a pneumatic tire according to any one of claims 1 to 6 . Forming a tread band by cylindrically winding a tire component including a belt and a tread rubber around the outer periphery of each drum sector divided in the circumferential direction of the forming drum,
transferring the tread band to a green tire molding position located on the outer diameter side of the cylindrical carcass band containing the carcass ply;
bulging the carcass band radially outward and bonding it to the inner peripheral portion of the tread band to form a green tire;
removing the molded green tire from the green tire molding position;
A method for manufacturing a pneumatic tire by vulcanizing and molding the removed green tire,
The number of divisions of the molding drum is 17 or 19,
The forming drum has the tread band formed on the outer peripheral portion of the drum sector, and a plurality of the drum sectors are annularly arranged with intervals in the circumferential direction,
The method for manufacturing a pneumatic tire, wherein the interval is set to 27 mm or less.

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