Patent Grant
8900389
This application is a U.S. National Phase under 35 U.S.C. §371, of International Application No. PCT/JP2007/056767, filed Mar. 29, 2007.
The present invention relates to methods for producing pneumatic tires, and more particularly, to a method for producing a pneumatic tire which can use existing facilities without change and does not make the spliced parts of an inner liner easily opened even if the tire is produced with use of an inner liner having a low adhesion.
There have been proposed pneumatic tires having an inner liner disposed beside the tire cavity as an air impermeable layer, the inner liner comprising a film formed of a thermoplastic resin as a main component instead of a conventional rubber in order to lighten the tire (see a patent document 1, for example).
Processes for producing such pneumatic tires include a process for winding a sheet-shaped film around a tire building drum of metal to form a cylindrical inner liner. Since the film has a low adhesion, adhesion between the film and the building drum is insufficient when the film has been wound around the building drum. As a result, the film is apt to fall off the building drum, and a problem is that it is difficult to wind the film around the building drum.
In order to solve the above problem, it is useful to provide a suction structure for suctioning the film on the building drum to hold it with use of negative pressure. However, it is required to newly provide the suction structure, and existing facilities can not be used without modification, which causes a problem of an increase in facility cost.
Further, the cylindrical inner liner is formed by splicing the winding-starting end and winding-finishing end of the sheet-shaped film. The film, however, has a low adhesion, and another problem is that, even if the inner liner can be formed by splicing the ends of the film, the spliced parts are easily opened when lifting is applied to the inner liner in a tire producing process.
Patent Document 1: Japanese Patent Application Kokai Publication HEI 10-35232
An object of the present invention is to provide a method for producing a pneumatic tire which can use existing facilities without change and does not make the spliced part of an inner liner easily opened even if the tire is produced with use of an inner liner having a low adhesion.
In order to achieve the above object, the present invention provides a method for producing a pneumatic tire having steps of winding an inner liner around a tire building drum to form a cylindrical body, the steps comprising: attaching a winding-starting end of the inner liner to the building drum via an uncured tacky member; winding the inner liner attached to the building drum around the building drum; and splicing a winding-finishing end side of the wound inner liner with the winding-starting end of the inner liner via the uncured tacky member to form the cylindrical body.
According to the present invention described above, the winding-starting end of the inner liner is attached to the building drum via the uncured tacky member, and the winding-finishing end side of the inner liner wound around the building drum is spliced with the winding-starting end of the inner liner via the uncured tacky member. Therefore, even when an inner liner having a low adhesion is used, the inner liner does not fall off the building drum. Accordingly, without providing a new suction structure, existing facilities can be used with no change.
Since the winding-starting end and winding-finishing end side of the inner liner are spliced with each other via the uncured tacky member, the spliced parts of the inner liner are not easily opened when lifting is applied to the inner liner during producing.
Embodiments of the present invention will be described in detail below with reference to the attached drawings.
Referring to
A carcass ply 4 extends between the right and left bead portions 3 inside the tire. The carcass ply has a rubber layer and reinforcing cords embedded therein. The reinforcing cords, which extend in the radial direction of the tire, are arranged at prescribed intervals in the circumferential direction of the tire. The carcass ply has opposite ends, which are turned up around bead cores 5 embedded in the bead portions 3 from the inner side of the tire toward the outer side with bead fillers 6 being sandwiched. An inner liner 8 is disposed inward of the carcass ply 4 via a tying rubber layer 7 for securing a good adhesion to the carcass ply 4.
The inner liner 8 comprises a film formed of a thermoplastic resin or thermoplastic elastomer composition comprising a blend of a thermoplastic resin and an elastomer, and acts as an air impermeable layer. As shown in
For the thermoplastic resin and thermoplastic elastomer composition used for the inner liner 8, conventionally known ones (see Japanese Patent Application Kokai Publication HEI 10-35232, for example) can be used; examples of the thermoplastic resin may include polyamide resins and polyester resins, and examples of the thermoplastic elastomer composition may include a blend of one of the above thermoplastic resins and diene rubber or olefin rubber as elastomer.
A plurality of belt plies 10 are provided radially outwardly of the carcass ply 4 in the tread portion 1. A tread rubber layer 11 is placed radially outwardly of the belt plies 10. A side rubber layer 12 is disposed outward of the carcass ply 4 in each sidewall portion 2, and a cushion rubber layer 13 is provided outward of the turned-up portion of the carcass ply 4 in each bead portion 3.
A method for producing the pneumatic tire of
First, as shown in
Once attachment of the winding-starting end 8′a of the inner liner 8′ is completed, the building drum 21 is rotated one revolution to wind the inner liner 8′ fully around the building drum 21. Then, as shown in
For the tacky member 9′, any tacky material may be used if the winding-starting end 8′a of the inner liner 8′ can be held on the building drum 21 and the spliced state can be maintained in such a manner that the opposite spliced ends 8′a and 8′b of the inner liner 8′ are not opened when lifting described later is applied thereto. One containing, for example, an epoxidized styrene-butadiene-styrene block copolymer is preferably used. The same goes for an uncured sheet-shaped tacky member 9″ described later.
It is generally preferable that the adhesion of the tacky member 9′ be higher. However, if it is excessively high, it is difficult to remove a first formed assembly 22 described later from the building drum 22. On the other hand, if the adhesion of the tacky member 9′ is too weak, the winding-starting end 8′a of the inner liner 8′ can not be held on the building drum 21, and the opposite spliced ends 8′a and 8′b of the inner liner 8′ is apt to open. Therefore, one suitable for the type and size of a tire used is selected.
After the cylindrical inner liner 8′ is formed, a first formed assembly 22 is formed by applying an unvulcanized tying rubber layer 7′, an unvulcanized carcass ply 4′, bead cores 5 with an unvulcanized bead filler 6′, unvulcanized cushion rubber layers 13′, and unvulcanized side rubber layers 12′ as is conventional (see
The first formed assembly 22 is removed from the building drum 21, mounted on a shaping drum 23 and internally pressurized as shown in
The first formed assembly 22 is toroidally inflated by lifting and pressed against the radially inner side of a second formed assembly 24 disposed radially outwardly thereof to form a green tire, the second formed assembly comprising unvulcanized belt plies 10′ and an unvulcanized tread rubber layer 11′ disposed radially outwardly thereof. The green tire is set in a tire curing press and vulcanized to obtain a pneumatic tire of
According to the present invention described above, when the inner liner 8′ is wound around the building drum 21 to form the cylindrical body, the winding-starting end 8′a of the inner liner 8′ is attached to the building drum 21 via the tacky member 9′, and the winding-finishing end 8′b of the wound inner liner 8′ is spliced with the winding-starting end 8′a of the inner liner 8′ via the tacky member 9′. Therefore, even when a film of a thermoplastic resin or thermoplastic elastomer composition having a low adhesion is used for the inner liner 8′, the inner liner 8′ does not fall off the building drum 21. Accordingly, without providing a new suction structure, existing facilities can be used with no change.
Since the winding-starting end 8′a and winding-finishing end 8′b of the inner liner 8′ are spliced with each other via the tacky member 9′, the opposite spliced ends 8′a and 8′b of the cylindrical inner liner 8′ are not easily opened when lifting is applied to the cylindrical inner liner 8′ during producing.
Referring to
More specifically, as shown in
Referring to
In the case of the inner liner 8′ with the uncured sheet-shaped tacky member 9″ preliminarily applied to the outer surface as described above, as shown in
In the third embodiment, the tacky member 9″ is provided on the entire outer surface of the inner liner 8′. Therefore, the opposite ends 8′a and 8′b of the inner liner 8′ may be spliced with each other in a butting manner via the tacky member 9″ in the alternative of splicing in the overlapping manner. In the case where the opposite ends 8′a and 8′b of the inner liner 8′ are spliced with each other in the overlapping manner via the tacky member 9″, it is sufficient to use an uncured tape-shaped tacky member (tacky member 9′ in
In the present invention, the thickness t of the uncured tacky member 9′, 9″ is preferably in the range of 0.3 mm to 3.0 mm, and is properly selected according to the type and size of a tire. If the thickness t of the tacky member 9′, 9″ is less than 0.3 mm, it is not preferable because the tacky member 9′, 9″ is apt to deform. If the thickness t of the tacky member 9′, 9″ is beyond 3.0 mm, it is not desirable from the viewpoint of weight. The thickness t of the tacky member 9′, 9″ can generally be about 0.4 to 1.5 mm in the case of pneumatic tires for passenger cars, and about 0.5 to 2.5 mm in the case of heavy duty pneumatic tires.
The length L1, in the circumferential direction of the drum, of the extension portion 9′x, 9″x of the tacky member 9′, 9″ adhered to the building drum 21, and the length L2, in the circumferential direction of the drum, of the one side portion 9′m of the tacky member 9′ are preferably equal to or more than 5 mm, respectively, in order to securely attach the inner liner 8′. The upper limits of the drum circumferential direction lengths L1 and L2 are dependent on adhesion, but in general, are preferably equal to or more than 15 mm from the viewpoint of facilitating a removal operation of the first formed assembly 22, the tacky member 9′, 9″ of which is adhered tightly to the building drum 21, from the building drum 21.
In the case where the opposite ends 8′a and 8′b of the inner liner 8′ are spliced with each other in the overlapping manner, the overlapping length OL is preferably equal to or more than 3 mm from the viewpoint of preventing the opposite spliced ends 8′a and 8′b of the inner liner 8′ from opening during lifting. The upper limit of the overlapping length OL is preferably equal to or less than 10 mm. The overlapping length OL is more preferably about 3 mm to 5 mm.
The length, in the widthwise direction of the tire, of the tacky member 9′ and 9″ is desirably the same as that of the inner liner 8′ as described above in light of securely attaching the inner liner 8′ to the building drum 21 and preventing the opposite spliced ends 8′a and 8′b of the inner liner 8′ from opening during lifting. However, it may be less than that, and can be properly selected. The tire widthwise direction length of the tacky member 9′, and 9″ is preferably the same as that of at least a region which is located between the right and left unvulcanized bead fillers 6′ and receives relatively great deformation during lifting.
The above embodiments show examples of the inner liner 8′ formed from a film of a thermoplastic resin or thermoplastic elastomer composition. However, the inner liner may be one having the film and a rubber layer laminated outward thereof. It is sufficient for the inner liner 8′ to have at least the film on a side facing the building drum 21.
The inner liner 8′ that is weak in adhesion is not limited to the above-described film of a thermoplastic resin or thermoplastic elastomer composition. The inner liner may be any inner liner if it is formed of a material which is weak in adhesion. The inner liner may be one formed of, for example, rubber (butyl rubber or diene rubber, for example) having a weak adhesion. The inner liner may also be one formed from a plurality of plies including a film of a thermoplastic resin or thermoplastic elastomer composition and a layer of rubber with a weak adhesion laminated thereon.
The above embodiments each show an example of using the uncured tacky member 9′, 9″ of one layer. However, an uncured tacky member formed from a plurality of layers may be used. In the case of the uncured tacky member formed from a plurality of layers, it is preferable that it comprise at least two uncured tacky layers 9′A and 9′B having different adhesions as shown in
The pneumatic tire produced according to the method of the present invention is not limited to the above-described pneumatic tire having a construction shown in
The present invention can be applied to any if it is a method for producing a pneumatic tire with use of an inner liner 8′ having a weak adhesion.
Green tires each having a construction shown in
As a comparative example, the result when an inner liner was attached to the building drum without using an tacky member is also shown in Table 1. It should be noted that as a tire curing press having the building drum, an existing one having no suction structure for suctioning and holding an inner liner was used.
Inner Liner Attachment Condition
A condition when the inner liner was attached to the building drum was visually observed, and was judged from the result thereof on three levels of ◯, Δ, and X. ◯ means that the inner liner was attached to the building drum without any problems. Δ means that the inner liner was attached to the building drum, but the uncured tacky member was deformed and the inner liner partially fell off the building drum. X means that the inner liner could not be attached to the building drum.
Inner Liner Opposite Ends Splice Condition
The green tire was cannibalized, and a splice condition of the opposite ends of the inner liner spliced in an overlapping manner was visually observed and was judged from the result thereof on two levels of ◯ and X. ◯ means that the opposite ends of the inner liner was spliced and there was no opening. X means that the opposite ends of the inner liner was opened and not spliced.
As seen from Table 1, the pneumatic tire producing method of the present invention can produce a pneumatic tire without opening the spliced opposite ends of the inner liner while existing facilities are used without modification; accordingly, the pneumatic tire producing method of the present invention can use existing facilities without change and does not make the spliced parts of an inner liner easily opened even if the pneumatic tire is produced with use of an inner liner having a low adhesion.
The method for producing a pneumatic tire according to the present invention having the aforementioned excellent effects is preferably applicable to production of a pneumatic tire having a inner liner with a low adhesion.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-090536 | Mar 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/056767 | 3/29/2007 | WO | 00 | 8/7/2008 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2007/114204 | 10/11/2007 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5938869 | Kaido et al. | Aug 1999 | A |
| 6079466 | Watanabe et al. | Jun 2000 | A |
| 6477894 | Koch et al. | Nov 2002 | B1 |
| 20050217774 | Borot | Oct 2005 | A1 |
| Number | Date | Country |
|---|---|---|
| 41 11 448 | Oct 1992 | DE |
| 4111448 | Oct 1992 | DE |
| 1 145 872 | Oct 2001 | EP |
| 2 299 978 | Sep 1976 | FR |
| U 62-121923 | Aug 1987 | JP |
| 06055661 | Mar 1994 | JP |
| A 6-55661 | Mar 1994 | JP |
| 06156007 | Jun 1994 | JP |
| 08244402 | Sep 1996 | JP |
| A 8-244402 | Sep 1996 | JP |
| 10006414 | Jan 1998 | JP |
| A 10-6414 | Jan 1998 | JP |
| A 10-35232 | Feb 1998 | JP |
| A 2004-148953 | May 2004 | JP |
| A 2004-351810 | Dec 2004 | JP |
| 2005068173 | Mar 2005 | JP |
| A 2005-297963 | Oct 2005 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20090173431 A1 | Jul 2009 | US |
