JPH03189131A - Manufacture for pneumatic tire - Google Patents

Abstract

PURPOSE:To splice easily without generating overlapping of carcass cords or turbulence, by a method wherein a lug part made of only rubber is fitted to an end part of a carcass material and lapping of the end parts each is performed by making use of the lug part. CONSTITUTION:A long sized beltlike rubber coated cord material 1 obtained by covering carcass cords 4, which are arranged in parallel with each other, with cord rubber is molded with a calender. The cord material 1 possesses a lug part 3 comprised of only a rubber part not containing the carcass cords 4 on one side end part 10. The formed cord material 1 is cut off along a cut line 2 and a rectangular carcass material 6 is formed. The carcass material 6 is wound up round the circumference of a molding dump 9, the lug part 3 is lapped on one side end part 10' and the same is apliced. In this instance, the lug parts 3 are superposed upon each other so that a cord 4a positioning at the outer most end of a lug part 3 side and a cord 4b positioning at the outer most end of the end part 10' not having a lug part come into contact almost with a vertical line 7.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a pneumatic tire.

More specifically, the present invention relates to a method for manufacturing a pneumatic tire that allows the ends of carcass plies to be spliced together with high precision without requiring any skill, and that enables the manufacture of high-quality tires.

[Conventional technology]

Conventionally, generally, cylindrical pneumatic tires are formed using strip-shaped materials during tire manufacture, including the carcass, inner liner, outer cap tread, and side tread that make up the pneumatic tire. ing. That is, these strip-shaped materials are formed into a cylindrical shape by splicing their ends so that they overlap each other.

The lap-shaped splice portion formed in this way forms a thick step diagonally across the circumferential direction of the tire, and has greater rigidity than other portions. Therefore, when such tires rotate, periodic radial force variations (RF
V) was unavoidable.

The present inventors found that among the belt-shaped tire constituent materials that affect RFV, the influence exerted by the splice part of the carcass does not simply increase RFV due to differences in level or rigidity (the following tire It was discovered that problems related to surface level differences also occur.

That is, the carcass material is made up of a carcass cord embedded within a rubber layer of coated rubber.

Therefore, when a sheet of carcass material is wrapped around a forming drum and both ends are spliced into a lap shape, the carcass cords overlap, causing blue streaks called bumpy ply sides (BPS) to form on the side of the tire. A bulge appears as if it is standing up.

As mentioned above, as a method of joining carcass materials so as to eliminate the occurrence of overlapping of carcass cords, a so-called butt splice, in which the ends of the carcass materials are joined by butting each other, is known. . However, it requires a high level of skill to butt the ends of the carcass materials together without causing any overlap, and the work must be done with careful attention, which reduces work efficiency. What's more, it had the serious drawback that if tension was applied to the joint, the wall thickness of the joint would become smaller, the cords would become unevenly spaced, and in the worst case, they would peel off.

[Problem to be solved by the invention]

The present invention has been made in view of such conventional drawbacks, and its purpose is to easily splice the ends of carcass materials together without causing disturbance to the carcass cord, without requiring a high level of skill. The purpose of the present invention is to provide a manufacturing method that can produce high-quality pneumatic tires.

[Means to solve the problem]

That is, in the method for manufacturing a pneumatic tire of the present invention, ears made only of rubber are formed at one end of a sheet-like carcass material in which a carcass cord is covered with rubber, and the carcass material with ears is formed into a cylindrical shape on a forming drum. After wrapping the ends of the ears and the other ends together, beads are attached to each side edge of this cylindrical carcass material, and then the center part of the outer periphery of this cylindrical carcass material is attached. It is characterized by laminating a cap tread on the top and side trends on both sides.

Hereinafter, the method for manufacturing a pneumatic tire according to the present invention will be specifically explained.

As shown in FIG. 1, first, a long belt-shaped rubber-coated cord material 1, in which carcass cords 4 arranged in parallel are covered with coat rubber 5, is formed using a calender (not shown). This cord material 1 has an ear portion 3 at one end 10 consisting of only a rubber portion that does not include the carcass cord 4.
have. The width X of the ear portion 3 is 1.5 d or more, preferably 1.5 to 4 d in the case of steel cord, where d is the diameter of the carcass cord 4.

In the case of textile cords, the range is 2 to 10 d.

On the other hand, the width x1 of the rubber portion 3g at the other end 10' having no ears is approximately 0.5 to 1d.

Further, the width W between the end 10° and the outermost cord 4a on the ear side is equal to or slightly longer than the circumferential length of the forming drum 9.

The cord material 1 formed as above is cut at the cut line 2.
2 to form a rectangular carcass material 6 as shown in FIG. As shown in FIG. 3, the carcass material 6 is placed in a cell 8 together with the liner 7 while being arranged on a cloth liner 7 so that the carcass materials do not overlap.
Wind it up. The cell 8 in which the carcass material 6 has been wound up in this manner is transported to the next tire forming process.

As shown in FIG. 4, the carcass material 6 pulled out from the cell 8 carried to the tire forming process is wrapped around the forming drum 9, and the ear 3 is connected to the other end (the end without ear). Part) 10" Wrap and splice on top. At that time,
As shown in FIG. 5, in the ear portion 3, a cord 4a located at the outermost end on the side of the ear portion 3 and a cord 4b located at the outermost end on the end portion 101 side having no ear portion are connected to a vertical line 7. (However, it is acceptable for the two cords 4a and 4b to be somewhat similar in shape or to have some distance in the circumferential direction.) In this way, since the ear part 3 of the carcass material 6 is lapped and spliced to the other end 10'' which does not have an ear part, it is possible to splice the carcass material 6 by wrapping it to the other end 10'' where there is no ear part.
The ends 10, 10' can be easily lap spliced together. In other words, it is extremely difficult to butt the two ends together without leaving any gaps;
In the case of wrapping, there is a margin for joining due to the overlap, so the workability of lap splicing of the carcass material 6 is improved, and moreover, the carcass cord is not disturbed.

Both side portions of the cylindrical carcass 11 thus formed are squeezed as shown in FIG. 6, and an annular bead 13 is attached to each of the squeezed portions 12.

When the bead installation is completed, as shown in FIG. 7, both sides of the cylindrical carcass 11 are folded back using the expansion of the turn-up bladder 14 to form a primary grease tire 15. Furthermore, band-shaped side treads 16 are wrapped around each of the folded side portions, and the ends are spliced together.

The primary green tire 15 formed in this way is
For secondary molding, as shown in FIG. 8, the molding drum 9 is transferred to a molding drum 17 for secondary molding.

And a pair of left and right forming drums 17.17 for secondary forming.
When the primary green tire 15 is mounted on the vehicle, the inner bladder 18 is expanded in the radial direction, and the left and right forming drums 17. Ru. At this time,
The lap splice portion of the carcass material 6 undergoes some relative movement in the circumferential direction, and the two outermost carcass cords 4a, 4b of the carcass material 6 are also spaced at the same spacing as the other carcass cords 4.

After the primary green tire 15 is inflated in this way, the end portions of the side treads 16 are partially peeled off as shown in FIG. A band-shaped cap trend 20 with a belt 19 laminated on the inside is wrapped around it, and the ends are spliced together.

Next, as shown in FIG. 10, the cap tread 20
Both sides of the primary green tire 15 are brought into close contact with the primary green tire 15, and the ends of the side tread 16 are brought into close contact thereon to form a green tire 21.

As shown in FIG. 11, the completed green tire 21 is removed from the bladder 18 and then transferred to a vulcanization process.
It is vulcanized and molded in a mold. At this time, the lap splice part, in particular the lap splice part of the carcass material 6, is connected to the ear part 3.
flows and is joined in an almost flat state. As a result, a uniform joint is obtained without overlapping carcass cords or disorder of the carcass cords (and without unevenness at the joint).

In the pneumatic tire manufactured by the method described above, there is no overlapping of the carcass cords or disturbance of the carcass cords at the wrapped splice portion of the cylindrical carcass 11. Therefore, since this pneumatic tire has no step difference or rigidity difference caused by the lap-like splice portion, deterioration in radial force variation (RFV) is eliminated and tire uniformity (UF) is improved. Also, Bumpy Bligh Side (BPS)
The tires are also much smaller than conventional pneumatic tires, significantly improving the quality of the tires.

〔Effect of the invention〕

As mentioned above, the pneumatic tire obtained by the method of the present invention is produced by attaching rubber-only ears to the ends when splicing the ends of carcass materials together, and using the ears. Since the ends are lapped together, splicing can be easily performed without special training and without overlapping or disturbing the carcass cords. In addition, since there is no overlap of carcass cords or disturbance of carcass cords, the resulting tire is
RFV is reduced and tire uniformity is improved. The bumpy ply sides are also much smaller than in conventional pneumatic tires, significantly improving tire quality.

〔Example〕

A tire of the present invention manufactured using a carcass material having ears made only of rubber without a carcass cord, and a conventional tire manufactured using a carcass material without ears, were each
Prepare this book, Radial Force Variation (RF
V) and bumpy ply side (BPS) were measured.

The tire size for both tires is 215/
It was 65R15.

(Left below) (1) For RFV 4U2 (a) Rim used: 61/2JJ (standard rim) (bl
Load: 522kg (C) Air pressure: 2. Okg/cm2(d) Number of rotations: 60 rpm As a result, the RFV of the conventional tire was about 13 kg, whereas the RFV of the tire of the present invention was about 5 kg.

(218 PS The tire of the present invention has a bumpy ply side of 0.32
It was ~0.52m. In contrast, the bumpy ply side of conventional tires was approximately 0.711IA.

[Brief explanation of drawings]

FIGS. 1 to 12 are explanatory diagrams showing the method for manufacturing a pneumatic tire according to the present invention in order of steps. 3... Ear portion, 4... Carcass cord, 5... Rubber, 6... Carcass material, 9... Molding drum, 10.
101... End portion, 11... Cylindrical carcass material, 1
3... Bead, 16... Side trend, 20...
・Cap tread.

Claims (1)

[Claims] An ear made only of rubber is formed at one end of a sheet-like carcass material in which a carcass cord is covered with rubber, and this carcass material with ears is wound around a forming drum in a cylindrical shape, and the end of the ear and other After the ends are lapped together, beads are attached to each side edge of this cylindrical carcass material, and then a cap tread is laminated at the center of the outer circumference of this cylindrical carcass material, and side treads are laminated on each side. A method of manufacturing pneumatic tires.