JPS60184831A - Manufacture of pneumatic tire with lug - Google Patents

Abstract

PURPOSE:To prevent a disarray at the end of a cord outermost layer of a cord fabric layer with green rubber or a semi-vulcanized rubber as carcass cord layer by making rubber adhere to the entire circumferential surface of a body of a green tire before the vulcanization thereof. CONSTITUTION:A pair of right and left bead sections 12 are wound on a cylindrical former 11 while a plurality of cord fabric layers 13 with a green or semi- vulcanized rubber are wound thereon extending to said the bead sections 12. In addition, to prevent possible disarray of the cord in the vulcanization molding, a green tire 10 having a rubber sheet 14 comprising only a green or semi-vulcanized rubber stuck thereon is molded separately. This tire 10 is mounted on an insert die element 18 through a tire mounting machine while a circular slag, namely, a green rubber 27 making a part of a lug or tread section is mounted on the mating surface 26 of a lower die element 7. This rubber 27 is made to fluidize inward diametrically to adhere to the green tire 10 integrally and vulcanized by heating to complete a specified tire.

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing lug pneumatic tires.

Conventionally, when manufacturing pneumatic tires, tire components such as rubberized cord cloth layers and beads are sequentially stretched on a metal cylindrical former, and then an extruded tread rubber layer is further wrapped around the outermost layer. After attaching and molding a so-called green tire, it is removed from the former, and then this green tire is placed in a vulcanization mold and shaved into a toroidal shape with, for example, a bladder, while being heated and pressurized. It was then vulcanized and made into a finished tire.

By the way, the tread surface of a completed tire has a tread pattern (uneven pattern) that has been devised in various ways in order to obtain a predetermined tire performance.

For this reason, the tread pattern has different thicknesses.

On the other hand, the extruded tread rubber layer used when forming a green tire must have a uniform thickness in its longitudinal direction.

For this purpose, as shown in Figure 1, the tread surface after vulcanization (
In the tread rubber layer (3) having lugs (2) in 1), the tread rubber flows violently and its movement also affects the cord fabric layer (4), and as a result, the inner surface of the lugs (2) A concave surface (5) may be formed.

In addition, if the difference in height between the lug (2) and the tread surface (1) becomes extreme as shown in Figure 2, the concave surface (5) will expose the cord fabric layer (4) at the base of the lug (2). ).

Also, while a large amount of rubber is required for the lug (2), not so much rubber is required between the lugs (2), but in the conventional method, the tread rubber layer (
As for 3), the thickness must be uniform in the longitudinal direction, so the thickness is determined according to the lug portion.

For this reason, the areas between the lugs that do not require much rubber are extremely thick as shown in FIG. 3, and as a result, the inner surface of the tread portion has a corrugated shape in the circumferential direction corresponding to the number of lugs.

For these reasons, the conventional general tire manufacturing method increases the weight of the tire (due to excessive material), increases cost, and worsens straight-line performance.

This is causing deterioration in field performance.

In particular, pneumatic tires for rice transplanters are highly recommended! Webbed blades (a type of lug) are formed from the standpoint of increasing the tire capacity by one load, and agricultural tires such as binders and combines become so-called high-lug tires, making the above-mentioned problems more noticeable. It is.

From this point of view, for example, there is a method for manufacturing a pneumatic tire disclosed in Japanese Patent Publication No. 56672/1983.

The advantages of this are recognized.

However, in this conventional example, the tread rubber layer is molded in advance as a crown shape connected in the circumferential direction of the tire, and the inner periphery of the crown-shaped tread rubber layer is mainly coated with a rubberized cord cloth layer formed separately on a former. Since the raw case body, which consists of a tread and a pair of beads, is deformed into a toroidal shape and bonded together, the tread rubber layer must necessarily be unvulcanized or semi-vulcanized. Therefore, when the upper mold is opened and the core mold is removed, the rubber layer will not stick to the core mold, and the tread rubber layer will not remain in the mold, or even if it remains, it will be deformed. There is.

Therefore, in this conventional example, it is necessary to apply chrome plating to at least all parts of the surface of the core mold that come into contact with the molded rubber, and on the other hand, the corresponding surface of the mold must be specially treated by making it rough. Even with these special modifications, the tread rubber layer may remain deformed within the mold, which can result in tires with irregular shapes. Furthermore, it was necessary to inflate the raw case body, which was extremely difficult to control.

The present invention provides a new lug pneumatic tire manufacturing method that eliminates all the drawbacks of the general tire manufacturing method using an extruded tread rubber layer and the conventional tire manufacturing method using a molded tread rubber layer as described above. Particularly, the present invention is characterized in that the outermost cord end of the unvulcanized or semi-vulcanized rubberized cord cloth layer, which is a cascord layer, is prevented from being disturbed. purpose.

Therefore, according to the present invention, a cavity having the shape of a pneumatic tire with lugs to be produced is composed of at least three matching mold parts: an upper mold element, a lower mold element and a core mold element, which can be clamped. In a method for manufacturing a pneumatic tire with lugs using a tire manufacturing machine, a green tire having multiple layers of unvulcanized or semi-vulcanized rubberized cord cloth covering a pair of left and right bead portions is separately formed, The green tire is set in a splittable metal core element.

To load the metal core mold element into the cavity, set the outermost layer end of the rubberized cord cloth layer of the green tire so that it is closer to the lower mold element than the mating surfaces of the upper and lower mold elements, and then, A volume of rubber corresponding to the respective volumes of the tread surface layer including the lugs, the sidewall surface layer, and the bead portion surface layer is filled into the cavity from the opposite side from the terminal, and the rubber is applied to the entire outer peripheral surface of the tire body of the green tire. The present invention provides a method for manufacturing a pneumatic tire with lugs, which is characterized in that the lug pneumatic tire is bonded over the entire tire and then vulcanized.

Note that the lugs herein are defined as including the blades of pneumatic tires for rice transplanters.

Embodiments of the present invention will be described in detail with reference to FIG. 3 and subsequent figures.

Figures 3 and 4 show the forming process or procedure for the green tire αQ, and Figure 4 shows a general cylindrical former - αυ
Wrap a pair of left and right bead parts (2) on top, and
A plurality of unvulcanized or semi-vulcanized rubberized cord cloth layers α3 are wrapped around the bead portion (2), and an unvulcanized cord cloth layer α3 is further wrapped around the bead portion (2) to prevent the cord from being disturbed during vulcanization molding, which will be described later. A green tire αQ to which a rubber sheet α made of vulcanized or semi-vulcanized rubber is attached is separately molded.

In the example of FIG. 5, a pair of left and right beads (2), unvulcanized, are placed on the core-shaped element a9, which can be raised and lowered by a cylinder device (not shown), using a known tire cord mounting machine or manually. Alternatively, a semi-vulcanized rubber cord cloth layer α3 is wrapped and attached, and a green tire αQ is formed on which a rubber sheet α made of only unvulcanized or semi-vulcanized rubber is provided.

Here, the core-shaped element α9 consists of a first mold (15 mm) and a second mold (150) slidably attached to the first mold (15B) via a holder (15B), and the outer peripheral surface shape is It has a shape that follows the inner shape of the main body.

In addition, the cord of the cord cloth layer a3 may be made of nylon, polyester, rayon, or other synthetic or artificial fibers or natural fibers with low elongation, metal materials such as steel or aluminum, or composite materials thereof. It may also be a monofilament, a tape, a sash, or a thick-edged cord, on which an unvulcanized or semi-vulcanized topping rubber is provided.

Also, the rubber sheet α is in the form of a strip.

Although not shown, it is provided around the cord cloth layer α3.

A green tire On is formed which constitutes part or all of the rubber material of the tire body, such as abrasion gum strip and sidewall rubber, and has a carcass part here.

Therefore, the outermost layer end (13A) of the cord cloth layer (end) of this green tire αQ is coated with a plurality of layers over the bead part (end) so that the outermost layer end (13A) is located on either side of the tire <100 meridian plane. Can be attached.

Note that when the rubberized cord cloth layer a3 is semi-vulcanized, the rubber sheet (141) may not be necessary.

The green tire θ1 formed or molded as described above is mounted on a tire manufacturing machine shown in FIGS. 6 and 7.

The tire manufacturing machine is composed of at least three matching mold parts: an upper mold element αG, a lower mold element 0η, and a core mold element α. In this embodiment, the lower mold element (17) is fixed. Relative to this, the lower mold element (17) and the core mold element α are movable up and down, and the upper and lower mold elements (lf19Qη) are capable of closing and opening the mold.

When the molds are matched, a cavity 09 having the outer shape of the pneumatic tire with lugs to be manufactured can be formed, and in this embodiment, the lug molding part - shown by the blades that protrude largely from the sidewall part to the tread part. The upper and lower die elements ufDQ are formed at predetermined intervals in the circumferential direction, and a plurality of trapezoidal lug molding parts Qυ are formed at predetermined intervals in the circumferential direction between the lug molding parts. In addition, depending on the case.

The molded part Qη is unnecessary.

The core type element θ & is made to be able to move up and down by having a cylinder (not shown) attached to an annular rim (support), and a first type (C) is attached to the rim (A) via a bolt (C). Type 1 (
A split mold made of metal (steel, aluminum, etc.) that can be freely divided is attached to C) with the second mold (C) slidably fixed via the handle @1, and the first mold (C) and the second mold are When the molds (C) are matched, the inner surface shape of the toroidal tire body is formed. In addition, this core mold element (to) is a core mold element for green tire molding (15
1 can also be used as is.

In this embodiment, the core-shaped element Q81 has a shape that subtracts part of the outer thickness of the tread gauge and side gauge, so the deducted gauge will be supplemented by the rubber described later. Become.

A separately molded green tire (10) is mounted on the core mold element (to) via a tire mounting machine, and this core mold element Q81 is attached to the lug molding part of the lower mold element αη as shown in FIG. − is charged correspondingly.

During this charging, as shown in Fig. 6, the cord cloth layer αJ
The cord terminal (13A) is inserted and set so that it is positioned closer to the lower die element α force than the mating surface (E).

Furthermore, an annular slug, ie, unvulcanized rubber (A), which constitutes a part of the lug and tread portion, is attached to the mating surface (E) of the lower mold element αη.

Therefore, this rubber (a) has a capacity at least equivalent to the lug volume, and as shown in FIG. The resulting disturbance of the cords in the unvulcanized cord cloth layer 03 is prevented by the rubber sheet α bleeding. In addition, when the cord cloth layer α3 is semi-vulcanized (it may be unvulcanized), the rubber material is used as a tread.
The lugs can be made different from the tire itself.

Then, this rubber (goods) is flowed inward in the radial direction, adhesively integrated with the green tire αQ, and heated and vulcanized to complete a predetermined tire.

Here, the flow of the rubber wire for mold clamping first flows toward the upper mold element OdO, which has a larger gap than the lower mold element αη, which is filled to the full gauge of the y body.
Therefore, with this flow of rubber (4), if the rubber sheet α is not provided and the cord terminal (13A) is located on the upper mold element αG side, it will be disturbed, and the rubber sheet α If there is bleeding, a code terminal (13mm)
If it is located on the upper mold element αQ side, it will be disturbed by the flow of rubber (A) that fills the upper mold element αG and flows backward CB).

In order to prevent such cord terminal (13A) from being disturbed.

The terminal (13A)'ft regardless of the presence or absence of rubber sheet α seepage.
The lower die element αη side, that is, the mating surface (which is the supply part of the rubber wire)
This is prevented partly because it is positioned lower than e) and fills the cavity on the upper mold element αG side, weakening its momentum.

In addition, when a block shape is used as the rubber wire, the cross section thereof may be of any shape such as circular, rectangular, or square, and may be arranged at predetermined intervals in the circumferential direction depending on the case.

In addition, as for the rubber (c), the rubber injection port (
E) may be formed, and from this day (C), rubber is injected by injection or the like to fill the cavity A9. In this case, a plurality of rubber injection ports (C) are formed radially in the cavity Q9. It is said that there is communication in
Also, an air vent is formed. And in any case,
The rubber supply section is located on the opposite side from the terminal (13A).

In this example, a pneumatic tire (2) having a blade lug (to) and a trapezoidal lug of 0υ on the tire body is vulcanized and molded, and the process of opening the mold, disassembling the core mold elements, etc. After passing through the steps, the tire is transferred to the next inspection step, etc. by a tire unloading machine (unloader, etc.).

8 to 13 show agricultural wheels made of hunter tires of various shapes that can be manufactured by the method of the present invention, and FIGS. 8 to 11 show agricultural wheels made mainly of pneumatic tires for rice transplanters. 12 and 13 show agricultural tires and wheels used as binders, combines, etc.

The wheels shown in Figs. 8 and 9 have a toroidal surface (29mm) in which the inner circumferential surface of the tire is formed by the metal outer circumferential surface of a core-shaped element, and are mounted on a wheel consisting of spoke faces and a rim (b). It is composed of

The blade lugs (7) are inclined with respect to the wheel rotation direction (0), and trapezoidal lugs 6υ are arranged in a row on the tread portion at intervals between the blade lugs (7).

The blade lugs (to) may be a double-wing type with a series of them on both sides, or a single-wing type with a staggered arrangement in the circumferential direction,
In any case, the tire is continuous from the tread part through the shoulder part to the middle of the tire sidewall part.

The multi-layer cord a3, which is the carcass cord layer, is made of beads (
(to), and its both terminals (13A) (13J1)
is at a symmetrical position at the shoulder with respect to the tire meridian plane.

In FIG. 10, the - terminal (15A) is located on the bead wall.

The other terminal (13B) is located near the meridian plane, and in FIG. 11, both terminals (13AX13B) are located on the bead wall.

In Fig. 10, the flexible part of the side wool part (29B
) is provided with an inner cord made of the same material as the cord αa, and also an outer cord (in FIG. 11) is provided, and these cords are provided during green tire molding. In addition, the reinforcement cord (to) (
) may be provided on both the inner and outer, or may be provided in a single layer between the inner and outer, or together with the inner and outer.

In addition, as mentioned above, it is desirable that the rubber that makes up the tire body and the rubber that makes up the tire tread have different rubber properties due to their functions. The JISA hardness of the part is about 40' to 70'.

The JISA hardness of the tread part including the lugs is 60G to 8.
00, and no matter which range is selected, the difference in hardness between the two is 10° or more. Here, the hardness is after vulcanization.

Therefore, for the rice transplanters shown in Figures 8 to 12, the blade lug 01J requires considerable rigidity in order to obtain tractive force, while the sidewall part is flexible (from the viewpoint of vibration absorption). However, the desired tire can be obtained by simply changing the rubber properties of the tire body and lug parts (which may or may not include part of the tread and part of the sidewall). be able to.

Further, even in the case of the high lug type shown in Fig. 12.13, the lug portion can be made rigid and wear resistant. Furthermore, when the rubber sheet aa+ is used, its physical properties can be the same as or different from those of the rubber (2) or the tire body.

In summary, according to the present invention, a green tire having multiple layers of rubberized cord cloth surrounding the pair of bead portions is set in a splittable core-shaped element, and this is inserted into a cavity. Since the cavity is filled with rubber equivalent to the lug volume and vulcanization molded, the inner shape of the tire is physically secured by the core element during vulcanization molding, so there is no need for expansion of the Prada, etc. becomes.

In addition, regardless of whether the rubberized cord cloth layer is unvulcanized or semi-vulcanized,
Since the outermost layer terminal is on the lower mold element side, and the rubber supply section is located on the opposite side from the terminal, there is little disturbance of the cord terminal due to the flowing rubber, which prevents cracks from occurring from the cord terminal. It is possible to manufacture tires with reduced

Furthermore, since the rubber for the lugs does not need to be opened from the time the lug is injected into the mold and fills the cavity until the end of vulcanization, there is no deformation within the mold and the structure is uniform. A pneumatic tire with lugs of a predetermined shape can be manufactured using the minimum amount of rubber required.

In addition, since the rubber for the lugs is flowed separately into the mold in addition to the rubber for the tire body, the tire body has soft elasticity and the lugs have high rigidity. Can be done.

[Brief explanation of drawings]

1 to 5 are explanatory diagrams of the tread portion showing a conventional example,
FIG. 4 is an explanatory diagram of a first example of green tire molding according to the present invention, FIG. 5 is a sectional view of a main part of a second example of the same, and FIG. 6 is a sectional view of a main part of a tire manufacturing machine of the present invention. FIG. 7 is a sectional view of the same mold-clamped state, FIG. 8 is a front view of the first example of the tire obtained by the present invention, and FIGS.
Figure 1 is a cross-sectional view showing three examples along the arrow D-D in Figure 8;
Figures 1 and 16 are cross-sectional views of agricultural tire wheels. αQ...Green tire, (2)-...Bead part,
(13... Cord cloth layer with rubber, (13mu)... Cord terminal, αG... Upper mold element, αη-- Lower mold element,
αe... Core type element, o9... Cavity, Han...
・Lug molding part, (A)...Mating surface, (Foundation)...Rubber.

Claims (1)

[Claims] 1. A clampable tire making machine is provided in which a cavity having the shape of a pneumatic tire with lugs to be produced is composed of at least three conformable mold parts: an upper mold element, a lower mold element and a core mold element. In this method, a green tire having multiple layers of unvulcanized or semi-vulcanized rubberized cord cloth covering a pair of left and right bead portions is separately formed, and the green tire is divided. When setting the metal core mold element into a flexible metal core mold element and inserting the metal core mold element into the cavity, align the outermost layer end of the rubberized cord fabric layer of the green tire with the mating surface of the upper and lower mold elements. Then, fill the cavity from the opposite side from the end with a volume of rubber corresponding to the volume of the tread surface layer including the lugs, the sidewall surface layer, and the bead surface layer. A method for manufacturing a puffer pneumatic tire, comprising: bonding the rubber over the entire outer peripheral surface of a tire body of a green tire, and then vulcanizing it.