JP4212923B2 - Tire tread rubber molding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire tread rubber molding apparatus, and more particularly, when a conductive grounding rubber is inserted into a tire tread rubber having a cap tread formed of non-conductive rubber, a simple modification to an existing molding apparatus. TECHNICAL FIELD The present invention relates to a tire tread rubber molding apparatus that can be molded simply by adding a.
[0002]
[Prior art]
Pneumatic tires with a tread made of silica-based rubber compound with high silica content are attracting attention not only because of their low rolling resistance, but also excellent fuel efficiency and braking performance on wet roads. . However, the silica rubber compound has the above-mentioned advantages, but has a characteristic that the grounding function with respect to the road surface is extremely low because the electric resistance is larger than that of the conventional carbon black rubber compound. Therefore, it is easy to accumulate static electricity in the vehicle, and there is a concern that the accumulated static electricity may cause noise trouble in the car radio or cause a spark phenomenon to cause a fire.
[0003]
As a solution to such a problem, a conductive carbon black rubber compound is inserted into the vehicle from the tread surface to the under tread as a thin ground rubber layer with respect to the cap tread of the silica rubber compound. Many techniques for preventing static electricity from accumulating have been proposed. In addition, as a facility that enables the production of tire tread rubber with such a grounding rubber inserted at low cost, it consists of a conductive carbon black rubber compound by simply remodeling an existing tread rubber molding device. There is a proposal that a part of the unvulcanized rubber for the under tread or the unvulcanized rubber for the wing tip is inserted into the non-conductive cap tread as a rubber for grounding (Patent Document 1, Patent Document 2, etc.).
[0004]
The tire tread rubber molding apparatus is fitted with a mini insert block at a position immediately before the extrusion die, and a part of the unvulcanized rubber for the under tread or the unvulcanized rubber for the wing tip is diverted to the mini insert block, The structure is such that it is guided to the center of the non-conductive cap tread and interrupted as a thin ground rubber.
[0005]
However, the structure becomes complicated because the mini insert block is inserted in a narrow space immediately before the extrusion die, and this complexity makes it difficult to disassemble and reassemble the extrusion head periodically, and maintenance work is required. There was a problem that it was extremely complicated.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-240081 [Patent Document 2]
Japanese Patent Laid-Open No. 11-262944
[Problems to be solved by the invention]
An object of the present invention is to use an existing molding apparatus when molding a tire tread rubber in which a part of unvulcanized rubber for conductive wing chips is inserted as ground rubber into unvulcanized rubber for non-conductive cap tread. Provided is a tire tread rubber molding device that can be molded by simple modification and can be easily maintained.
[0008]
[Means for Solving the Problems]
A tire tread rubber molding apparatus according to the present invention that achieves the above-described object is provided with a flow path of a conductive unvulcanized rubber UT for an under tread and a non-conductive unvulcanized rubber CT for a cap tread on a preform die. Road and conductive left and right wing chip flow path for unvulcanized rubber WT are juxtaposed, and an extrusion die is mounted on the discharge side of the preform die, and the extrusion die is placed up and down across the extrusion port. The upper die and the lower die are arranged, and the middle die having guide passages for introducing the unvulcanized rubber WT for wing tips into the inlets provided on the left and right sides and guiding them to both ends of the extrusion port, In a molding apparatus for extruding the unvulcanized rubber UT, CT, WT as an integral tire tread rubber from an extrusion die,
A dividing wall that bisects the upstream portion of the extrusion port to the left and right, a guide groove that communicates with the left and right inlets, a communication hole that penetrates from the middle of the guide groove to the surface side, and the communication hole And a discharge orifice that opens to the extrusion port via the front side of the dividing wall.
[0009]
Thus, the middle die, the dividing wall that bisects the upstream side of the extrusion port to the left and right, the guide groove that communicates with the left and right inlets, the communication hole that penetrates from the middle of the guide groove to the surface side, and the communication hole And a discharge orifice that opens to the extrusion port via the front surface side of the dividing wall, and the preform die is a non-conductive cap only by processing the extrusion die without any changes. A tire tread rubber having a grounding rubber can be obtained by separating the unvulcanized rubber CT for tread from the left and right by a dividing wall and injecting a part of the conductive unvulcanized rubber WT for the wing chip therebetween. it can.
[0010]
Moreover, it is substantially the same as in the case of existing equipment, because it is only necessary to process dividing walls, guide grooves, communication holes, discharge orifices, etc. in the middle die, which is a component part of the existing extrusion die, with almost no change in external size. In the same operation, the upper die and the lower die can be assembled, disassembly and reassembly work during disassembly and cleaning can be simplified, and maintenance management work can be facilitated.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the term “non-conductive” refers to a case where the electric resistance value of the rubber after vulcanization is 10 ⁹ Ωcm or more, preferably 10 ¹⁰ Ωcm or more. In the present invention, such non-conductive rubber is used as unvulcanized rubber for cap treads. Moreover, as such a non-conductive rubber | gum for non-conductive cap treads, the silica-type rubber compound which blended the silica as a main component highly can be used preferably. Silica rubber compounds, especially when used in tread rubber, can reduce the rolling resistance of pneumatic tires and lower the fuel consumption rate, and the rubber hardness decreases and the adhesion friction force against the road surface increases. The braking performance on a wet road surface can be improved.
[0012]
On the other hand, the term “conductive” refers to the case where the electrical resistance value of the rubber after vulcanization is less than 10 ¹⁰ Ωcm, preferably less than 10 ⁹ Ωcm. In the present invention, such a conductive rubber is used as an unvulcanized rubber for an under tread or an unvulcanized rubber for a wing chip. As the conductive unvulcanized rubber, a carbon black rubber compound that is used in conventional regular tires and that contains carbon black as a main component is preferably used. Since the carbon black rubber compound is conductive, there is no problem of accumulating static electricity in the vehicle unlike the silica rubber compound.
[0013]
The present invention is characterized in that a part of the unvulcanized rubber for the conductive wing tip is used as a grounding rubber.
[0014]
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings.
[0015]
1 and 2 illustrate a tire tread rubber molding apparatus according to the present invention. FIG. 1 is an exploded perspective view when viewed from the extrusion die side (front side), and FIG. It is a disassembled perspective view when seen from the side.
[0016]
1 and 2, 1 is an extrusion die and 2 is a preform die, which are assembled together. The extrusion die 1 is a part for finally extruding the tire tread rubber T, and is composed of three parts, an upper die 3, a lower die 4, and an intermediate die 5, and is fitted into a recess 24 formed on the front wall of the preform die 2. It is supposed to be.
[0017]
The preform die 2 includes a flow path 21 for the unvulcanized rubber UT for undertread, a flow path 22 for the unvulcanized rubber CT for cap tread, and a flow path for the unvulcanized rubber WT for wing chips. 23 penetrates in the front-rear direction, and the distance between them gradually approaches as it goes forward. Of these, two flow paths 23 for the unvulcanized rubber WT for wing chips are provided on both the left and right sides. Through these flow paths 21, 22, and 23, conductive under-tread unvulcanized rubber UT, non-conductive cap tread unvulcanized rubber CT, and conductive wing tip un-vulcanized rubber WT are pre-treated. It is supplied from the back of the foam die 2 to the extrusion die 1 side.
[0018]
As shown in detail in FIGS. 3 to 5 (A), (B), and (C), the extrusion die 1 has a plate-like middle die 5 fitted on the back surface of the plate-like upper die 3, and the upper die. 3, a plate-like lower die 4 is integrally connected by a bolt 7 so that the extrusion die 1 forms a plate-like rectangle as a whole even after assembly. In this way, the individual parts are plate-like, and are plate-like with substantially the same width even after assembly, which facilitates handling and facilitates maintenance management.
[0019]
An extrusion port 6 is formed between the upper die 3 and the lower die 4 in which the middle die 5 is fitted, and the tire tread rubber T is extruded from the extrusion port 6. In the lower die 4, an inclined surface 8 is formed at a portion corresponding to the extrusion port 6 so that the unvulcanized rubber CT for cap tread and the unvulcanized rubber UT for undertread smoothly merge at the extrusion port 6. It has become.
[0020]
The middle die 5 is formed with a dividing wall 9 at the center of the extrusion port 6 in the width direction, and the dividing wall 9 temporarily bisects the unvulcanized rubber CT for cap tread flowing toward the extrusion port 6. ing. In addition, on the back surface of the middle die 5 (inflow side of unvulcanized rubber), inlets 10 and 10 for receiving the unvulcanized rubber WT for wing tips are provided on the left and right sides, respectively. The inflow port 10 penetrates from the back side to the front side, and further communicates with the end of the extrusion port 6 through the guide groove 11. It is made to laminate.
[0021]
In addition, on the back side of the middle die 5, guide grooves 12 extending toward the center and guide grooves 13 extending outward are provided on the left and right sides of each inflow port 10, respectively. The guide grooves 12, 12 extending from the respective inlets 10, 10 toward the center side have a groove width that increases toward the center side, and a communication hole 14 that extends back and forth is provided at the center portion. Thus, the flow rate and flow velocity of the unvulcanized rubber WT for wing tips are stabilized by gradually increasing the width of the guide groove 12 toward the communication hole 14. On the front side through which the communication hole 14 passes, a discharge orifice 15 is provided so as to descend to the front side of the dividing wall 9, and its discharge end is opened in the middle of the extrusion port 6.
[0022]
The unvulcanized rubber WT for wing tips received in the guide grooves 12 and 13 is collected at the inlet 10 and supplied to the end of the extrusion port 6. However, a part of the unvulcanized rubber WT for the wing tip received in the guide groove 12 on the center side enters the communication hole 14 and is discharged from the communication hole 14 to the center in the width direction of the extrusion port 6 through the discharge orifice 15. The Since the discharge orifice 15 is provided on the front surface side of the dividing wall 9, the unvulcanized rubber WT for wing tips discharged from the discharge orifice 15 is temporarily bisected by the dividing wall 9 and unvulcanized for cap tread. It is injected between the rubbers CT, CT, merged so as to be sandwiched between the two unvulcanized rubbers CT, CT, and then discharged from the extrusion port 6.
[0023]
As described above, when the unvulcanized rubber WT for the wing tip is injected between the halved cap tread unvulcanized rubbers CT and CT, the guide groove 12 is gradually grooved toward the communication hole 14 as described above. If the width is increased, the flow rate and flow rate of the unvulcanized rubber WT for wing tips are stabilized, so that the composite of the unvulcanized rubber WT and CT, CT can be stabilized. Of course, the guide grooves 12 may be formed to have the same width as shown in FIG.
[0024]
The opposing surface on the discharge side of the discharge orifice 15 is an inclined surface 8 of the lower die 4, and it is preferable that a groove 16 is provided on the inclined surface 8 along the rubber flow of the extrusion port 6 (FIG. 4, (See FIG. 5C). By providing such a kerf 16, the unvulcanized rubber WT for the wing tip discharged from the discharge orifice 15 crosses the unvulcanized rubber CT for the cap tread and reaches the unvulcanized rubber UT for the undertread. Therefore, it is possible to eliminate the formation of an incomplete tread rubber in which the ground rubber does not reach the surface of the unvulcanized rubber UT for the under tread from the tread surface.
[0025]
The molding apparatus of the present invention compositely molds the tread rubber in which the unvulcanized rubber WT for the wing tip is inserted as the ground rubber as described above with only the extrusion die 3 having a thickness of about 20 mm. Among them, the middle die 5 is about ½ of 10 mm, in which the unvulcanized rubber WT for wing tips is guided to the center by the guide groove 12, and left and right by the communication hole 14 and the discharge orifice 15 formed in the center. It is characterized in that it is injected between the unvulcanized rubber for cap tread CT and CT divided into two.
[0026]
The width of the thin earth rubber thus obtained is preferably in the range of 0.1 to 2 mm. Further, in order to mold such a thin rubber for grounding, the width of the discharge orifice 15 is preferably in the range of 0.5 to 10 mm.
[0027]
The molding apparatus of the present invention configured as described above includes an unvulcanized rubber CT extruder for a non-conductive cap tread (not shown), an unvulcanized rubber UT extruder for a conductive undertread, and a conductive wing tip. The unvulcanized rubber WT extruder is connected to a flow path at each extrusion end of the extruder and used for the manufacture of tire tread rubber. That is, each extruder has an unvulcanized rubber UT for undertread, an unvulcanized rubber CT for cap tread, and an unvulcanized rubber for wing chips, respectively, at the inlets of the channels 21, 22, and 23 of the preform die 2. Connected to supply WT.
[0028]
When each extruder is operated, each unvulcanized rubber supplied from each extruder to the front end of the preform die 2 is pressed by the unvulcanized rubber UT for the under tread and the unvulcanized rubber CT for the cap tread overlapping each other. Although entering the outlet 6, the unvulcanized rubber CT for cap tread is separated left and right by the dividing wall 9 of the middle die 6. Further, the unvulcanized rubber WT for the wing tip, which flows into the inlet 10 through the guide path 11, overlaps with the unvulcanized rubber UT for the under tread and the unvulcanized rubber CT for the cap tread, which overlaps as described above. It is joined to both ends. Further, a part of the unvulcanized rubber WT for wing chips passes through the communication hole 14 and is discharged from the discharge orifice 15 into the extrusion port 6 on the front end side of the dividing wall 9 and is divided into two by the dividing wall 9. It combines so that it may be pinched | interposed between unvulcanized rubber CT and CT, and it will become a tread rubber for tires from the extrusion port 6 in the composite state, and will be extruded.
[0029]
As shown in FIG. 7, the extruded tire tread rubber T is formed by laminating an unvulcanized rubber CT for a cap tread and an unvulcanized rubber UT for an undertread on the upper and lower sides and unwinged wing tips on both wings. Laminated rubber WT and WT are laminated, and the unvulcanized rubber WT for thin wing chips is penetrated from the tread surface to the unvulcanized rubber UT for the under tread in the approximate center of the unvulcanized rubber CT for cap tread. And it has the structure extended in the longitudinal direction (tire circumferential direction). The thin rubber at the center made of the unvulcanized rubber WT for wing chips functions as a ground rubber after being molded into a tire.
[0030]
As described above, in the tire tread rubber molding apparatus of the present invention, the middle die, the dividing wall that bisects the upstream side of the extrusion port into the left and right, the guide groove that communicates the left and right inflow ports, and the middle of the guide groove By simply forming a communication hole penetrating to the surface side and a discharge orifice opening from the communication hole through the front surface side of the dividing wall to the extrusion port, a non-conductive unvulcanized rubber CT for cap tread Can be separated into left and right by a dividing wall, and a part of the unvulcanized rubber WT for conductive wing chips is injected between them to obtain a tread rubber for tire in which a grounding rubber is formed.
[0031]
Moreover, it is substantially the same as in the case of existing equipment, because it is only necessary to process dividing walls, guide grooves, communication holes, discharge orifices, etc. in the middle die, which is a component part of the existing extrusion die, with almost no change in external size. In the same operation, the upper die and the lower die can be assembled, so that disassembly and reassembly during disassembly and cleaning can be simplified, and maintenance management work can be facilitated.
[0032]
In addition, the tire tread rubber molding apparatus of the present invention is a modification that only adds a separation wall, a guide groove, a communication hole, and a discharge orifice while keeping the original die of the extrusion die of the existing molding apparatus, If the middle die can be replaced with an existing middle die that is not provided with a separation wall or the like, it can be used as a conventional tread rubber molding apparatus for regular tires.
[0033]
【The invention's effect】
As described above, according to the present invention, when a tire tread rubber in which a part of an unvulcanized rubber for a conductive wing tip is inserted as a ground rubber into an unvulcanized rubber for a non-conductive cap tread is molded, A dividing wall that bisects the upstream side of the extrusion port into left and right sides, a guide groove that communicates with the left and right inlets, a communication hole that penetrates from the middle of the guide groove to the surface side, and the communication A discharge orifice that opens from the hole to the extrusion port through the front side of the dividing wall is formed. The preform die can be made non-conductive only by processing the extrusion die without any changes. A tire tread rubber having a grounding rubber is obtained by separating the unvulcanized rubber CT for cap tread from the left and right with a dividing wall, and injecting a part of the unvulcanized rubber WT for conductive wing chips therebetween. Can
[0034]
Moreover, it is substantially the same as in the case of existing equipment, because it is only necessary to process dividing walls, guide grooves, communication holes, discharge orifices, etc. in the middle die, which is a component part of the existing extrusion die, with almost no change in external size. In the same operation, the upper die and the lower die can be assembled, disassembly and reassembly work during disassembly and cleaning can be simplified, and maintenance management work can be facilitated.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a tire tread rubber molding apparatus according to the present invention when viewed from an extrusion die side (front side).
FIG. 2 is an exploded perspective view of the tire tread rubber molding apparatus of FIG. 1 as viewed from the back side on the opposite side.
FIG. 3 is a front view (front view) of an extrusion die constituting the molding apparatus of the present invention.
4 is a rear view of the extrusion die of FIG. 3. FIG.
5A is a view taken along the line XX in FIG. 4, FIG. 5B is a view taken along the line YY in FIG. 4, and FIG. 5C is a view taken along the line ZZ in FIG.
6 is a rear view showing another embodiment corresponding to FIG. 4; FIG.
FIG. 7 is a cross-sectional view of a tire tread rubber molded by the molding apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Extrusion die 2 Preform die 3 Upper die 4 Lower die 5 Middle die 6 Discharge port 9 Dividing wall 10 Inlet 12 Guide groove 14 Communication hole 15 Discharge orifice 16 Cut groove 21 (Unvulcanized rubber UT for undertread) flow Channel 22 (of unvulcanized rubber CT for cap tread) Channel 23 (of unvulcanized rubber WT for wing tip) Channel UT Unvulcanized rubber CT for under tread Unvulcanized rubber WT for cap tread Unused for wing tip Vulcanized rubber

Claims (5)

The preform die is provided with a conductive unvulcanized rubber UT channel for undertread, a non-conductive cap tread unvulcanized rubber CT channel, and conductive left and right wing tip unvulcanized rubber WT. A flow path is juxtaposed, an extrusion die is mounted on the discharge side of the preform die, the upper die and the lower die arranged vertically with the extrusion die sandwiched between the extrusion ports, and the inlets provided on the left and right A middle die having guide passages for introducing unvulcanized rubber WT for wing chips into both ends of the extrusion port, and integrating the unvulcanized rubbers UT, CT, and WT from the extrusion die In the molding equipment to extrude as tread rubber for
A dividing wall that bisects the upstream portion of the extrusion port to the left and right, a guide groove that communicates with the left and right inlets, a communication hole that penetrates from the middle of the guide groove to the surface side, and the communication hole A tire tread rubber molding apparatus in which a discharge orifice that opens to the extrusion port via the front side of the dividing wall is formed. 2. The tire tread rubber molding apparatus according to claim 1, wherein the groove width of the guide groove is formed so as to increase from the inlet side toward the center side. The upper die, the lower die, and the middle die are each formed into a plate-like outer shape, and the outer shape of the extrusion die after the upper die, the lower die, and the middle die are integrally assembled is a rectangular plate shape. Or a tire tread rubber molding apparatus according to 2; The tire tread rubber molding apparatus according to claim 1, 2 or 3, wherein a cut groove is provided on the surface of the lower die facing the discharge side of the discharge orifice. 5. The molding apparatus according to claim 1, 2, 3 or 4, wherein a part of the unvulcanized rubber WT for wing tips is used for a thin ground in the middle of the cap tread unvulcanized rubber CT in the tire width direction. A method for producing a tread rubber for a tire that is inserted so as to penetrate in the thickness direction as rubber.

Images