JP2017030429A - Tread, mold for tread molding, tread molding method and green tire molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of easily stitching down a wing rubber even if a strong-rigidity breaker is used in molding of a green tire to prevent occurrence of a defect such that the wing rubber comes off from a sidewall.SOLUTION: A tread is characterized in that the cross-sectional shape of a wing rubber is an acute triangle. A mold for tread molding comprises: a first preformer in which flow channels of a bottom rubber, base rubber, cap rubber and wing rubber are individually provided; a second preformer in which the flow channel of a laminate of the bottom rubber, base rubber and cap rubber laminated by combination of the upper and lower molds, and wing rubber-inducing flow channels inducing the wing rubber to both outsides of the flow channel of the laminate are formed; and a die plate. The flow channel of the wing rubber in the first preformer is provided below the flow channel of the bottom rubber, and the wing rubber-inducing flow channel in the second preformer is provided at a lower mold side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a technique for forming a tread used for manufacturing a pneumatic tire.

  Pneumatic tires are laminated and affixed with inner liner, carcass, breaker, etc., shaped into the shape of the tire, then molded with a tread and sidewalls to form a raw tire, and the molded raw tire is vulcanized Manufactured by molding.

  At the time of forming the green tire, the attached tread is then pressed so as to bend toward the side portion from the contact surface (stitch down process), and is pressed onto the sidewall.

  FIG. 3 is a cross-sectional view schematically showing a structure before a conventional tread is attached. As shown in FIG. 3, the tread 1 is formed by integrally extruding a sheet-like under rubber 4, a base rubber 3, and a cap rubber 2 in order at the center, and a wing rubber 5 disposed on both outer sides. (For example, patent document 1).

  When a stitch down process is performed on such a tread, a raw tire is formed by pressing the wing rubber 5 so that the wing rubber 5 is bent and pressed against the sidewall.

JP 2008-23743 A

  However, in the stitch-down process as described above, for example, if a breaker having a high rigidity is used as a breaker serving as a base of a tread, it is difficult to stitch down the wing rubber. There was a problem that the rubber floated from the side wall, and there was a need for improvement.

  Therefore, the present invention suppresses the occurrence of the problem that the wing rubber floats up from the sidewall by easily stitching down the wing rubber even when a strong breaker is used in forming the raw tire. It is an object to provide a technology that can be used.

  As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by the invention described below, and has completed the present invention.

The invention described in claim 1
A laminate in which under rubber, base rubber, and cap rubber are laminated in order,
A tread provided with wing rubber provided on both outer sides of the laminate,
The tread is characterized in that the cross-sectional shape of the wing rubber is an acute triangle.

The invention described in claim 2
A tread mold used for extruding the tread according to claim 1,
A first preformer in which an under rubber flow path, a base rubber flow path, a cap rubber flow path, and a wing rubber flow path are individually provided;
An upper mold and a lower mold are configured, and by combining the upper mold and the lower mold, a flow path of a laminate in which the under rubber, the base rubber, and the cap rubber are laminated, and the laminate A second preformer formed with wing rubber guiding channels for guiding the wing rubber on both outer sides of the channel,
A die plate for extruding the tread having a predetermined shape by integrating each rubber;
The wing rubber channel is provided below the under rubber channel in the first preformer, and the wing rubber guide channel is provided on the lower mold side in the second preformer. This is a tread mold.

The invention according to claim 3
Using the tread molding die according to claim 2, the under rubber, the base rubber, the cap rubber, and the wing rubber are integrally extruded to form the under rubber, the base rubber, and the cap rubber. It is a tread molding method characterized by molding a tread in which the wing rubber having an acute triangular cross section is disposed on both outer sides.

The invention according to claim 4
A green tire molding method for molding a green tire using the tread according to claim 1,
A method for forming a raw tire, characterized in that the tread affixed on a breaker is pressed so as to curve from the laminate toward the wing rubber, and the bottom surface of the wing rubber is pressure-bonded to a sidewall. is there.

  According to the present invention, even when a breaker having a high rigidity is used in forming a raw tire, the wing rubber can be easily stitched down to suppress the occurrence of a problem that the wing rubber floats from the sidewall. Technology that can be provided.

It is sectional drawing which shows typically the structure before sticking of the tread which concerns on one embodiment of this invention. 1 is an exploded perspective view of a tread mold according to an embodiment of the present invention. It is sectional drawing which shows typically the structure before the pasting of the conventional tread. It is a disassembled perspective view of the conventional mold for tread molding.

1. Background to the Present Invention (1) Structure of Tread The present inventor can easily stitch down a wing rubber even when a strong breaker that is difficult to stitch down is used. In order to suppress the lifting of the wing, a method for ensuring sufficient adhesion between the wing rubber and the sidewall was studied.

  As a result, if the side of the wing rubber that contacts the side wall (ie, the bottom surface of the wing rubber) is enlarged, a sufficient bonding area is secured between the wing rubber and the side wall when stitching down. As a result, a tread having a structure as shown in FIG. 1 was conceived.

  FIG. 1 is a cross-sectional view schematically showing a structure before attaching a tread according to an embodiment of the present invention. In the tread according to the present embodiment shown in FIG. 1, the wing rubber 5 having a cross section of an obtuse triangle (see FIG. 3) is formed into an acute triangle, and the bottom surface of the wing rubber 5 is lower than that of the conventional tread 1. Is also getting bigger. As a result, when stitching down, it is possible to secure a sufficient adhesion area between the wing rubber and the sidewall and properly crimp it, even when a strong breaker that is difficult to stitch down is used In addition, the wing rubber can be prevented from floating after stitching down.

(2) Tread Molding Mold Next, the inventor examined a tread molding mold as a specific molding technique for such a tread.

(A) Conventional Tread Molding Mold FIG. 4 is an exploded perspective view of a tread molding mold used for molding the conventional tread shown in FIG. Conventionally, raw rubber for each rubber member (under rubber 4, base rubber 3, cap rubber 2, wing rubber 5 shown in FIG. 3) is used as a first preformer C, a second preform, as shown in FIG. The tread was integrally extruded by passing through the reformer D and the die plate E in this order.

  Specifically, in the first preformer C, an under rubber flow path 8, a base rubber flow path 7, and a cap rubber flow path 6 are individually provided in order from the bottom. A pair of left and right wing rubber flow paths 9 is provided above 6. By supplying each raw rubber to these flow paths, an under rubber, a base rubber, a cap rubber, and a wing rubber are formed.

  The second preformer D is composed of an upper mold D1 and a lower mold D2. Between the upper mold D1 and the lower mold D2, there is provided a laminated flow path 10 in which an under rubber, a base rubber, and a cap rubber that have passed through the first preformer C are laminated to form a laminated body. Further, in the vicinity of both outer sides of the flow path 10 of the laminate of the upper mold D1, wing rubber guiding flow paths 11 for guiding the wing rubber that has passed through the first preformer C are provided.

  The die plate E is provided with an extrusion port 12, and each rubber that has passed through the second preformer D is integrated and extruded in the flow path to the extrusion port 12. The tread shown is molded.

(B) Tread molding die according to the present embodiment The inventor examined a tread molding die capable of molding a tread as shown in FIG. 1 in which the side in contact with the sidewall of the wing rubber is enlarged. The inventors have come up with a tread mold as shown in FIG. FIG. 2 is an exploded perspective view of a tread mold according to an embodiment of the present invention.

  As shown in FIG. 2, the tread molding die according to the present embodiment is provided with a first preformer A, a second preformer B, and a die plate E, so that a conventional tread molding die is provided. Similar to mold.

  However, in the first preformer A, a pair of left and right wing rubber flow paths 9 are provided below the under rubber flow path 8, and in the second preformer B, the wing rubber guiding flow path 11 is a lower mold. It differs from a conventional tread molding die in that it is provided on the B2 side.

  By using such a tread molding die, it is possible to obtain a tread 1 in which the cross-sectional shape of the wing rubber 5 as shown in FIG. 1 is an acute triangle. As described above, such a tread 1 can secure a sufficient adhesion area between the wing rubber and the side wall at the time of stitching down, and can be properly crimped. Even if it is used, the wing rubber can be prevented from floating after stitching down.

2. Tread Molding Method According to the Present Embodiment Hereinafter, a tread molding method using the above-described tread molding die according to the present embodiment will be described.

  First, under rubber, base rubber, cap rubber, and wing rubber are respectively supplied to each flow path of the first preformer A, and each rubber member after passing through the first preformer A is moved to the second preform. Supply to Reformer B.

  At this time, in the present embodiment, unlike the conventional case, the wing rubber flow path 9 is provided below the under rubber flow path 8, so that the wing rubber flows in the first preformer A. The second preformer B is supplied through the lower side of the path 8.

  Next, the under rubber, base rubber, and cap rubber are supplied to the flow path 10 of the second preformer B laminate. Thereby, an under rubber, a base rubber, and a cap rubber are laminated to form a laminated body.

  On the other hand, in the first preformer A, the wing rubber supplied to the second preformer B through the lower rubber flow path 8 is supplied to the wing rubber guiding flow path 11 to flow the laminate. Guide around 10 outside.

  At this time, the second preformer B of the present embodiment is different from the second preformer D (see FIG. 4) in which the conventional wing rubber guiding channel 11 is provided in the upper mold D1. Since the flow path 11 is provided in the lower mold B2, the wing rubber is guided to the lower portions near both outer sides of the flow path 10 of the laminate.

  And the laminated body and wing rubber which passed the 2nd preformer B are supplied to the extrusion port 12 of the die plate E, and the laminated body and wing rubber of under rubber, base rubber, and cap rubber are integrated. Extrude the tread.

  At this time, in this embodiment, the wing rubber passes through the wing rubber channel 9 below the cap rubber channel 6 in the first preformer A, and the lower mold B2 of the second preformer B. After passing through the wing rubber guiding channel 11 provided on the side, the air is supplied to the extrusion port 12 of the die plate E.

  That is, in the present embodiment, unlike the conventional case where the wing rubber is supplied from the upper side, the wing rubber 5 is supplied from the lower side. The tread 1 in which the wing rubber 5 having an acute triangular cross section as shown in FIG. 1 is formed can be extruded.

  The wing rubber 5 is made of a soft and strong rubber material, and the tread 1 of this embodiment has a larger bottom surface than the conventional tread as shown in FIG. In the stitch-down process in the tire forming process, a sufficient bonding area can be secured between the wing rubber and the sidewall, and the pressure can be appropriately pressed. As a result, even when a breaker having high rigidity that is difficult to stitch down is used, the wing rubber can be prevented from floating after the stitch down.

  Hereinafter, the present invention will be specifically described with reference to examples.

1. Example, Comparative Example (1) Example A tread molding die of the present embodiment shown in FIG. 2 is mounted on a picker back extruder of φ200 × φ200 × φ120 × φ120, and the cross-sectional shape shown in FIG. The tread was integrally extruded.

  The tread to be formed is a tread for tires of size 155 / 65R14 (product number A), a tread for tires of size 215 / 45R18 (product number B), a tread for tires of size 205 / 55R16 (product number C), and a size. Four types of treads (product number D) for 155 / 65R13 tires were formed, and 10 lots were molded for each product number. The specific production numbers for each product number are as shown in Table 1.

(2) Comparative Example A tread was molded under the same conditions as in the example except that the conventional tread molding die shown in FIG. 4 was used to integrally extrude the tread having the cross-sectional shape shown in FIG.

2. Evaluation Each of the obtained treads was used to form a raw tire, and after performing the stitch-down process, it was visually confirmed whether or not the wing rubber was lifted. The number of tires in which the occurrence of lifting was recognized was measured as the number of defective occurrences, and the occurrence rate was calculated as the failure occurrence rate of the stitch-down process. The results are shown in Table 1.

  In addition, the breaker of rigidity according to each tire size was arrange | positioned under each tread of product number AD.

  It can be seen from Table 1 that in the comparative example, the wing rubber was lifted in any size of the green tire molding process, whereas in the example, the wing rubber was not lifted at all.

  Therefore, by using a tread mold as shown in FIG. 2 to form a tread whose wing rubber has an acute-angled cross section, a breaker having high rigidity that is difficult to be stitched down in the raw tire molding process. Even when it was used, it was confirmed that it was possible to suppress stitch-down defects (wing rubber floating).

  While the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1 Tread 2 Cap rubber 3 Base rubber 4 Under rubber 5 Wing rubber 6 Cap rubber flow path 7 Base rubber flow path 8 Under rubber flow path 9 Wing rubber flow path 10 Laminate flow path 11 Wing rubber induction flow path 12 Extrusion port A, C First preformer B, D Second preformer B1, D1 Upper mold B2, D2 Lower mold E Die plate

Claims (4)

A laminate in which under rubber, base rubber, and cap rubber are laminated in order,
A tread provided with wing rubber provided on both outer sides of the laminate,
A tread wherein the cross-sectional shape of the wing rubber is an acute triangle. A tread mold used for extruding the tread according to claim 1,
A first preformer in which an under rubber flow path, a base rubber flow path, a cap rubber flow path, and a wing rubber flow path are individually provided;
An upper mold and a lower mold are configured, and by combining the upper mold and the lower mold, a flow path of a laminate in which the under rubber, the base rubber, and the cap rubber are laminated, and the laminate A second preformer formed with wing rubber guiding channels for guiding the wing rubber on both outer sides of the channel,
A die plate for extruding the tread having a predetermined shape by integrating each rubber;
The wing rubber channel is provided below the under rubber channel in the first preformer, and the wing rubber guide channel is provided on the lower mold side in the second preformer. A tread molding die characterized by the above.   Using the tread molding die according to claim 2, the under rubber, the base rubber, the cap rubber, and the wing rubber are integrally extruded to form the under rubber, the base rubber, and the cap rubber. A tread molding method comprising molding a tread having the wing rubber having an acute triangle cross section on both outer sides. A green tire molding method for molding a green tire using the tread according to claim 1,
A method for forming a raw tire, comprising: pressing the tread affixed on a breaker so as to bend toward the wing rubber from the laminated body, and pressing the bottom surface of the wing rubber to a sidewall.

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