JPH04101835A - Forming method for pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the uniformity of a tire, while the gauge difference in the connected part of rubber sheets is made small by providing the steps of prescribed length at the front and rear of tubeless liner formed into the width almost corresponding to the peripheral length of a forming drum and the tie rubber stuck to the liner and by connecting them in forming process. CONSTITUTION:A tubeless liner 2 is formed into the width almost corresponding to the peripheral length (l) of a forming drum plus alpha, when it is calender- formed. Further, sticking steps H of 5-20mm are formed at the front and rear of the tubeless liner 2 and the tie rubber 3 to be stuck to the liner. When the rubber sheet 1 formed into the mutually stuck band shapes of two kinds is wound on a forming drum, it is cut into the length corresponding to the width of the forming drum, and is wound on a tire-forming drum in the state of being centered. When the sheet is wound, the parts 2a, 2b, and 3a, 3b of the distals to be connected are butt-connected with the compound of same kind.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for molding a pneumatic tire, and more specifically, to a method for forming a pneumatic tire, and more specifically, to reduce the level difference at the butt joint of rubber sheets, and to increase the bonding force at the butt joint. The present invention relates to a method for molding a pneumatic tire that can increase the uniformity of the pneumatic tire.

[Conventional technology] Conventionally, the method for forming tubeless pneumatic tires uses two types of rubber sheets, a tubeless liner and a tie rubber laminated together, and the tubeless liner is calendered to a width commensurate with the width of the forming drum. This is then wrapped around a tire forming drum.

[Problem that the invention seeks to solve]

For this reason, at the joint between the two types of rubber sheets, the pasted tubeless liner and tie rubber are alternately joined.
Since the same type of compound is not bonded, the adhesion after vulcanization and the difference in gauge with other parts may worsen tire uniformity and appearance, causing problems in tire quality.

[Object of the Invention] This invention was devised by paying attention to such conventional problems, and when forming a tubeless liner, the tubeless liner is formed with a width approximately corresponding to the circumference of the forming drum, and the tubeless liner and
By providing a step of a predetermined length at the front and rear of the tie rubber to be bonded to this and joining it, the gauge difference at the joint of the rubber sheet can be made smaller than before, improving tire uniformity. It is an object of the present invention to provide a method for molding a pneumatic tire that can increase the bonding force of the butt joint.

[Means to solve the problem]

In order to achieve the above object, the present invention has a width approximately corresponding to the circumference of the molding drum when molding the tubeless liner, and also has a predetermined length at the front and rear of the tubeless liner and the tie rubber bonded thereto. The two types of rubber sheets pasted together are cut into a length corresponding to the width of the tire forming drum, and when wrapped around the tire forming drum to form the tire, the end joints are coated with the same type of compound. The gist is to butt join.

[Action of the invention]

This invention is constructed as described above, and has 5 to 20 I
When forming a tire by wrapping it around a tire forming drum using the IIIn step, the end joints can be butt-joined with the same type of compound, so the difference in gauge at the joints of the rubber sheets can be compared with conventional methods. As a result, it is possible to improve tire uniformity and increase the bonding force of the butt joint.

[Embodiments of the invention] Hereinafter, the present invention will be described in detail based on the accompanying drawings.

FIG. 1 shows a cross-sectional view of a rubber sheet 1 according to the present invention, and the rubber sheet 1 is composed of a tubeless liner 2 and a tie rubber 3 pasted together, and the tubeless liner 2 is The tubeless liner 2 is molded with a width approximately corresponding to the circumferential length 2+α of the molding drum, and a bonding step H of 5 to 20 mm is formed at the front and rear of the tubeless liner 2 and the tie rubber 3 bonded thereto.

When wrapping the pasted rubber sheet 1 formed in two types of belt shapes around a forming drum (not shown), it is cut to a length corresponding to the width of the forming drum, and while being centered, the tire is formed. Wrap it around the drum. This wrapping sometimes causes the terminal joints 2a, 2b and 3a, 3b to
As shown in the figure, they are butt-jointed using the same type of compound.

By butt-jointing in this way, the gauge difference at the joint of the rubber sheets 1 can be made smaller than in the past, improving tire uniformity and increasing the joining force at the butt-joint. It is something that can be done.

Furthermore, when all the rubber sheets 1 are made of all-butyl liners, it is also possible to eliminate the masking tape that is required in the conventional method.

Furthermore, FIG. 3 shows another method of joining the end joining parts 2a, 2b and 3a, 3b of the rubber sheet l. In the first embodiment, a method of joining by butt joining was explained, but this method The second embodiment shows overlapping bonding.

That is, the end joint parts 2a, 2b, and 3a of the rubber sheet 1,
3b are stacked and bonded so that they are made of the same type of compound, it is possible to increase the bonding force of the bonded portion.

Moreover, FIG. 4 shows a cross section of the tire molded as described above after vulcanization. When the carcass member 4 is laminated on the tie rubber 3 and vulcanization molded, the rubber as shown in the figure There is not much difference in level between the end joining parts 2a, 2b and 3a, 3b of the sheet 1, and the appearance of the tire can also be improved.

〔Effect of the invention〕

In this invention, as described above, when forming the tubeless liner, it is formed with a width approximately corresponding to the circumference of the forming drum, and steps of a predetermined length are formed at the front and rear of the tubeless liner and the tie rubber bonded thereto. The two types of rubber sheets pasted together are cut to a length that corresponds to the width of the forming drum, and when wrapped around the tire forming drum to form the tire, the end joints are cut with a similar type of combiner. Since the rubber sheets are butt-jointed, the difference in gauge at the joint of the rubber sheets can be made smaller than before, and as a result, tire uniformity can be improved, and
This has the effect of dramatically increasing the bonding force of the butt joint after vulcanization.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a rubber sheet embodying this invention, FIG. 2 is a sectional view of a butt joint showing a first embodiment of this invention, and FIG. FIG. 4 is a sectional view of the butt joint of the first embodiment after vulcanization. 1...Rubber sheet, 2...Tubeless liner 3
...Tie rubber, 2a, 2b... End joint of tubeless liner, 3a, 3b... End joint of tie rubber.

Claims (1)

[Claims] In a method of molding a pneumatic tire using two types of rubber sheets in which a tubeless liner and tie rubber are laminated, the tubeless liner is molded to a width approximately corresponding to the circumference of the molding drum, and A step of a predetermined length is provided at the front and rear of the tubeless liner and the tie rubber that is bonded to it, and the two types of rubber sheets that are bonded are cut to a length that corresponds to the width of the forming drum. A method for forming a pneumatic tire, which is characterized in that when the tire is wound around a forming drum and formed, the end joints are butt-joined using the same type of compound.