JP4148788B2 - 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 enables stable molding 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, in this way, a thin ground rubber is inserted into the non-conductive cap tread in a narrow space just before the extrusion die, and at the same time, it is pushed out from the extrusion die immediately. However, there is a problem that inferior quality tread rubber is easily produced. In addition, 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 for maintenance and maintenance work. 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 an unvulcanized rubber for a conductive undertread is inserted as a ground rubber into an unvulcanized rubber for a nonconductive cap tread. An object of the present invention is to provide a tire tread rubber molding apparatus that enables stable molding only by simple modification and facilitates maintenance management of molding components.
[0008]
[Means for Solving the Problems]
The tire tread rubber molding apparatus of the present invention that achieves the above object includes a preform die ( 2 ) with a conductive under-tread unvulcanized rubber UT channel ( 21 ) and a non-conductive cap tread non-conductive. The unvulcanized rubber UT for the under tread and the unvulcanized for the cap tread , which are juxtaposed so as to penetrate the vulcanized rubber CT channel ( 22) in the front-rear direction and move through the respective channels (21, 22). In a molding apparatus in which the rubber CT is joined by an extrusion die ( 1) provided on the discharge side of the preform die ( 2 ) and extruded as an integral tire tread rubber,
The upstream surface of the preform die ( 2 ) straddles both the flow path (21) inlet of the unvulcanized rubber UT for undertread and the flow path (22) inlet of the unvulcanized rubber CT for cap tread. The auxiliary plate ( 3 ) is detachably disposed, and a pair of left and right openings (31, 31) corresponding to the inlet of the flow path (21) with the partition wall (34) interposed between the auxiliary plate ( 3 ). And a pair of left and right openings (32, 32) corresponding to the inlet of the flow path (22) are provided so as to penetrate in the front-rear direction, and the pair of openings (31, 31) are provided on the upstream rear surface of the dividing wall (34). The inlet (33) of the unvulcanized rubber UT for undertread is provided so as to be sandwiched between the pair of openings (32, 32) on the downstream side front surface. Equipped with a discharge slit (37) communicating with the The unvulcanized rubber UT for undertread discharged from the discharge slit (37) into a thin sheet is joined so as to be sandwiched between the unvulcanized rubber CT for cap tread discharged from the pair of openings (32, 32), The composite flow is made to flow into the flow path (22) .
[0009]
In this way, an operation for interrupting a part of the unvulcanized rubber UT for the under tread as an earth rubber into the unvulcanized rubber CT for the cap tread is not performed immediately before the extrusion die, but on the upstream side of the preform die. Since the composite flow is stabilized while the preform die is moved, it is pushed out from the extrusion die only, so that a stable composite tread rubber for a tire can be obtained.
[0010]
Further, an opening corresponding to both flow path inlets of the unvulcanized rubber UT for the under tread and the unvulcanized rubber CT for the cap tread, and a flow path inlet of the unvulcanized rubber CT for the cap tread are formed in a single auxiliary plate. The grounding rubber to the unvulcanized rubber CT for cap treads, such as the dividing wall that bisects, the discharge slit, the inlet of the unvulcanized rubber UT for undertread, and the guide path that leads from the inlet to the discharge slit, etc. All the components necessary for interrupting are combined into one, and this auxiliary plate is simply detachable from the back of the preform die, making it easy to disassemble and reassemble during disassembly and cleaning. The 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]
The conductive contrast, the electrical resistance of the rubber after vulcanization refers to a case of less than 10 ¹⁰ [Omega] cm, preferably it refers to the case of less than 10 ⁹ [Omega] cm. 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 conductive undertread is used as a rubber for grounding.
[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, 2 is a preform die, and 3 is an auxiliary plate, 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 11, a lower die 12, and an intermediate die 13, and is fitted into a recess 24 formed on the front wall of the preform die 2. It is supposed to be. As shown in detail in FIGS. 6A, 6 </ b> B, and 6 </ b> C, the extrusion die 1 has a middle die 13 fitted on the back surface of the upper die 11, and the upper die 11, the middle die 13, and the lower die 12. And the tire tread rubber T is extruded from the extrusion port 14. An inclined surface 18 is formed at a portion corresponding to the extrusion port 14 of the lower die 12 so that the unvulcanized rubber CT for cap tread and the unvulcanized rubber UT for undertread are smoothly joined.
[0017]
On the back surface of the middle die 13, a guide groove 15 that receives the unvulcanized rubber WT for wing tips and a converging port 16 that focuses the unvulcanized rubber WT received by the guide groove 15 are provided on both the left and right sides. . The left and right converging ports 16 penetrate the opposite sides of the middle die 13 and communicate with the wing portion at the end of the extrusion port 14 via the guide groove 17. Therefore, the unvulcanized rubber WT focused at the focusing port 16 is guided to the wing portion of the extrusion port 14 and integrated with the tread rubber T.
[0018]
The preform die 2 has a flat passage 21 for the unvulcanized rubber UT for undertread, a passage 22 for the unvulcanized rubber CT for cap tread, and a passage 23 for the unvulcanized rubber WT for wing tips. And the distance between them gradually approaches as it moves forward. Of these, two flow paths 23 for the unvulcanized rubber WT for wing chips are provided on both the left and right sides.
[0019]
A recess 25 is formed on the back surface of the preform die 2 so as to include the inlet of the flow path 22 of the unvulcanized rubber CT for cap tread and the inlet of the flow path 21 of the unvulcanized rubber UT for undertread. The auxiliary plate 3 having the same dimensional width as the preform die 2 is detachably fitted in the recess 25. In addition, the auxiliary plate 3 has left and right sides with a partition wall 34 so as to correspond to the inlet 22 of the unvulcanized rubber CT for cap tread and the inlet 21 of the unvulcanized rubber UT for undertread. A pair of openings 32, 32 and 31, 31 are provided so as to penetrate in the front-rear direction.
[0020]
As shown in detail in FIGS. 3 to 5, the auxiliary plate 3 is provided with a dividing wall 34 in the center in the width direction, and the dividing wall 34 divides the openings 32 and 32 into left and right, and the preform die 2. The inlet of the flow path 22 of the unvulcanized rubber CT for cap tread on the side is also divided into right and left. Therefore, the dividing wall 34 temporarily separates the unvulcanized rubber CT for cap tread flowing into the flow path 22 of the preform die 2 into two flows.
[0021]
Further, the auxiliary plate 3 opens an inlet 33 for receiving the unvulcanized rubber UT for undertread so as to be sandwiched between the left and right openings 31, 31 at the center on the back side, and guides the inlet 33. A narrow discharge slit 37 that opens to the front side through the passage 36 is communicated. The discharge slit 37 faces the inlet of the flow path 22 of the unvulcanized rubber CT for cap tread of the preform die 2, and its longitudinal direction crosses the entire thickness direction of the flow path 22.
[0022]
The discharge slit 37 discharges the unvulcanized rubber UT for undertread received from the inflow port 33 in a thin sheet shape, but is narrowed down at the end of the guide passage 36 so that the discharge slit 37 is discharged at the time of the discharge. The flow rate is increased. Thus, the thin unvulcanized rubber for undertread UT discharged from the discharge slit 37 is sandwiched between the unvulcanized rubber for cap tread CT, CT temporarily divided into two by the dividing wall 34 on both sides thereof. And flows in the flow path 22 of the preform die 2 toward the extrusion die 1 while being sandwiched. And while flowing through this flow path 22, the thin unvulcanized rubber UT for undertread is in a stable composite state while being familiar with the unvulcanized rubber CT and CT for cap tread on both sides.
[0023]
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 the flow path end of each extrusion port of the extruder and used for the manufacture of tire tread rubber. That is, each extruder has the unvulcanized rubber CT for cap tread and the unvulcanized rubber UT for undertread in the openings 32 and 31 of the auxiliary plate 3 and the unvulcanized rubber WT for wing chips of the preform die 2. It connects so that it may supply to the inlet_port | entrance of the flow path 23. FIG.
[0024]
When each extruder is operated, the unvulcanized rubber WT for wing tips flows into the flow path 23 of the preform die 2 as it is, but the unvulcanized rubber CT for cap tread and the unvulcanized rubber UT for undertread are It flows into the flow paths 22 and 21 of the preform die 2 through a pair of left and right openings 32, 32 and 31, 31 of the auxiliary plate 3, respectively.
[0025]
Further, a part of the unvulcanized rubber UT for undertread flows into the inflow port 33 and is discharged from the discharge slit 37 into the flow path 22 through the guide path 36 in the form of a thin sheet. In this way, the unvulcanized rubber for cap tread CT, CT divided into the left and right by the dividing wall 34 is joined to both sides of the unvulcanized rubber UT for under tread discharged in the form of a thin sheet, The composite state is stabilized while flowing in the flow path 22 of the preform die 2 for a while in the merged state, and reaches the extrusion die 1.
[0026]
The unvulcanized rubber that has flowed through the three flow paths 21, 22, 23 is joined together by the extrusion die 1 at the tip, and is extruded as a tire tread rubber T having a cross-sectional shape as shown in FIG. 7. . The extruded tire tread rubber T is formed by laminating unvulcanized rubber CT for cap tread and unvulcanized rubber UT for undertread vertically, and unvulcanized rubber WT and WT for wing tips on both wings. Further, a thin-walled unvulcanized rubber for undertread UT is penetrated from the tread surface to the lower unvulcanized rubber for undertread UT in the substantially central portion of the cap tread unvulcanized rubber CT, and the longitudinal direction ( The structure extends in the tire circumferential direction). This thin unvulcanized rubber UT for undertread functions as a grounding rubber after being molded into a tire.
[0027]
The width of the thin earth rubber thus obtained is preferably in the range of 0.1 to 2 mm. In order to mold such a thin ground rubber, the width of the discharge slit 37 is preferably in the range of 0.5 to 10 mm.
[0028]
As described above, in the tire tread rubber molding apparatus of the present invention, the operation of interrupting a part of the unvulcanized rubber UT for the under tread as the ground rubber into the unvulcanized rubber CT for the cap tread is performed immediately before the extrusion die. The tread for a tire in a stable composite state is not performed, but is carried out at the back of the preform die upstream of the preform die and is only extruded from the extrusion die after the composite flow is stabilized while the preform die is moved. Rubber can be obtained.
[0029]
Further, an opening corresponding to both flow path inlets of the unvulcanized rubber UT for the under tread and the unvulcanized rubber CT for the cap tread, and a flow path inlet of the unvulcanized rubber CT for the cap tread are formed in a single auxiliary plate. The grounding rubber to the unvulcanized rubber CT for cap treads, such as the dividing wall that bisects, the discharge slit, the inlet of the unvulcanized rubber UT for undertread, and the guide path that leads from the inlet to the discharge slit, etc. All the components necessary for interrupting are combined into one, and this auxiliary plate is simply detachable from the back of the preform die, making it easy to disassemble and reassemble during disassembly and cleaning. The maintenance management work of these molding parts can be facilitated.
[0030]
Moreover, since the tread rubber molding apparatus for tires of the present invention has a structure in which only one auxiliary plate is added to the existing molding apparatus, as the auxiliary plate, an inlet, a guide path, a discharge slit, a dividing wall, etc. The tread rubber molding device for inserting the ground rubber according to the present invention is prepared by preparing an auxiliary plate of the same size provided with only the openings 31 and 32 without being provided, and making this auxiliary plate replaceable. It can also be used as a tread rubber molding device for regular tires.
[0031]
Further, in the illustrated example, the dividing wall 34 and the discharge slit 37 are arranged at the center in the width direction of the auxiliary plate. However, the tire having the main groove in the tread center is modified by shifting the position to the side from the center. It can also be used as a tread rubber molding device.
[0032]
【The invention's effect】
As described above, according to the present invention, when molding a tread rubber for a tire in which a part of the unvulcanized rubber for a conductive undertread is inserted as a ground rubber into the unvulcanized rubber for a nonconductive cap tread, By simply modifying the molding apparatus, stable molding can be achieved, and maintenance management of molding parts 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 rear view of an auxiliary plate constituting the molding apparatus of the present invention.
4 is a front view (front view) of the auxiliary plate of FIG. 3;
FIG. 5 is a view taken along arrow XX in FIG. 4;
6A and 6B show an extrusion die constituting the molding apparatus of the present invention, in which FIG. 6A is a rear view, FIG. 6B is a front view (front view), and FIG. is there.
FIG. 7 is a cross-sectional view of a tire tread rubber molded by the molding apparatus of the present invention.
[Explanation of symbols]
1 Extrusion die 2 Preform die 3 Auxiliary plate 21 (for unvulcanized rubber UT for undertread) Channel 22 (for unvulcanized rubber CT for cap tread) Channel 23 (for unvulcanized rubber WT for wing tips) Flow path 31, 32 Opening 33 Inlet 34 Dividing wall 36 Guide path 37 Discharge slit UT Unvulcanized rubber CT for undertread CT Unvulcanized rubber WT for cap tread Unvulcanized rubber for wing chip

Claims (5)

The preform die (2) penetrates the flow path (21) of the unvulcanized rubber UT for conductive undertread and the flow path (22) of the unvulcanized rubber CT for non-conductive cap tread in the front-rear direction. The under-tread unvulcanized rubber UT and the cap tread unvulcanized rubber CT moving in the respective flow paths (21, 22) are provided on the discharge side of the preform die (2). In a molding device that is joined by an extrusion die (1) and extruded as an integral tire tread rubber,
An upstream rear surface of the preform die (2) spans both the flow path (21) inlet of the unvulcanized rubber UT for undertread and the flow path (22) inlet of the unvulcanized rubber CT for cap tread. The auxiliary plate (3) is detachably disposed, and a pair of left and right openings (31, 31) corresponding to the inlet of the flow path (21) with the dividing wall (34) interposed between the auxiliary plate (3). And a pair of left and right openings (32, 32) corresponding to the inlet of the flow path (22) are provided so as to penetrate in the front-rear direction, and the pair of openings (31, 31) are provided on the upstream rear surface of the dividing wall (34). The inlet (33) of the unvulcanized rubber UT for undertread is provided so as to be sandwiched between the pair of openings (32, 32) on the downstream side front surface. A discharge slit (37) communicating with the The unvulcanized rubber UT for undertread discharged from the exit slit (37) into a thin sheet is joined so as to be sandwiched between the unvulcanized rubber CT for cap tread discharged from the pair of openings (32, 32), A tire tread rubber molding apparatus configured to cause a composite flow to flow into the flow path (22).   2. The tire tread rubber molding apparatus according to claim 1, wherein the discharge slit (37) crosses the flow path (22) inlet of the cap tread unvulcanized rubber CT in the thickness direction. The tire tread rubber molding apparatus according to claim 1 or 2 , wherein the auxiliary plate (3) has substantially the same width as the preform die (2). The auxiliary plate (3) has the same size as the auxiliary plate (3) and has an opening (31) and an opening (32) corresponding to the inlet of the channel (21) and the inlet of the channel (22), respectively. The tire tread rubber molding apparatus according to any one of claims 1 to 3 , wherein the auxiliary plate provided only with a) is replaceable. Using the molding device according to any one of claims 1 to 4, wherein a portion of the unvulcanized rubber UT for undertread, thin ground rubber in the tire width direction intermediate the cap tread unvulcanized rubber CT The manufacturing method of the tread rubber for tires inserted so that it may penetrate as thickness direction.

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