JP2015051611A - Tire vulcanization mold and tire manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire vulcanization die capable of preventing rubber biting of a spring while suppressing bending deformation of a stem, and a method for manufacturing a tire using the same. A vent plug 2 includes a tubular housing 3, a stem 4 inserted into the housing 3, and a coiled spring that urges the stem 4 toward a cavity 15. The stem 4 has a columnar body 41 inserted into the spring 5 and a head 42 that closes the exhaust passage 21 by coming into contact with the inner surface of the opening 31 of the housing 3. The connecting end 41a of the body 41 connected to the head 42 has a larger diameter than the main body 41b of the body 41 surrounded by the spring 5. The top surface of the head 42 has a diameter larger than the inner diameter of the housing 3 into which the stem 4 is inserted. One or a plurality of protrusions 61 are provided on the side surface of the connecting end portion 41a, and the upper end position of the spring 5 is regulated by all or a part of the protrusions 61. [Selection diagram] Fig. 2

Description

  The present invention relates to a tire vulcanization mold in which a vent plug is attached to an exhaust hole of a molding surface in contact with an outer surface of a tire, and a tire manufacturing method using the same.

  In a tire vulcanization mold used for tire vulcanization molding, a large number of exhaust holes are provided on the molding surface in contact with the outer surface of the tire so that excess air between the tire and the molding surface is discharged to the outside. ing. Also, vent plugs attached to the exhaust holes are known in order to reduce the formation of rubber protrusions called spews. In Patent Documents 1 to 5, a vent plug (spring vent) is opened when a spring inserted into a tubular housing is biased by a spring, and closed when the outer surface of the tire is pushed down. Is disclosed.

  By the way, in the conventional vent plug, as in Patent Documents 1 to 3, the upper end position of the spring is regulated by the head portion of the stem, and the spring is arranged close to the molding surface. When it flows in, the inflow rubber may get entangled with the spring. If the spring is thus rubber-engaged, the inflow rubber is not removed when removing the vulcanized tire and the inflow rubber remaining in the housing prevents the spring from moving. It may cause malfunction.

  On the other hand, in the vent plugs described in Patent Documents 4 and 5, an annular protrusion along the circumferential direction is provided on the trunk portion of the stem, and the upper end position of the spring is regulated by the protrusion. However, in these vent plugs, the diameter of the trunk portion of the stem is constant, and the stem head portion and the trunk portion are connected through a relatively large step, so that the stem bends during repeated use. Prone to deformation. If the stem is bent, the inlet of the exhaust passage is locally expanded, and unvulcanized rubber easily flows into the housing, which is inconvenient.

International Publication No. 2006/070411 JP-A-2-214616 JP-A-9-141660 JP 2006-168253 A JP 2011-1116012 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tire vulcanization mold capable of preventing rubber engagement of a spring while suppressing bending deformation of a stem, and a method of manufacturing a tire using the same. It is to provide.

  The above object can be achieved by the present invention as described below. That is, a tire vulcanization mold according to the present invention includes a molding surface that is in contact with an outer surface of a tire set in a cavity, and a vent plug that is attached to an exhaust hole that is open on the molding surface. The vent plug includes a cylindrical housing having an exhaust passage therein, a stem that is inserted into the housing and serves as a valve body that opens and closes the exhaust passage, and the stem is opened to open the exhaust passage. A coil-shaped spring that is biased toward the cavity, and a head that closes the exhaust passage by contacting the stem with a columnar body inserted into the spring and an inner surface of the opening of the housing And the connecting end of the body connected to the head is larger in diameter than the body of the body surrounded by the spring, and the top surface of the head is The diameter of the housing is larger than the inner diameter of the housing into which the stem is inserted, and one or more protrusions are provided on the side surface of the connecting end, and the upper end position of the spring is regulated by all or part of the protrusions. It is what.

  In this mold, the trunk portion of the stem is connected to the head via a connecting end portion having a diameter larger than that of the body portion of the trunk portion, so that the difference in rigidity between the head portion of the stem and the trunk portion is small. The bending deformation of the stem can be appropriately suppressed. And since the protrusion which regulates the upper end position of a spring is provided in the side surface of the connection end part, even if a vent plug is in an open state, a spring is kept away from a molding surface. As a result, the rubber plug of the spring can be prevented so that the vent plug does not malfunction.

  It is preferable that the protrusion that regulates the upper end position of the spring is provided on the main body side of the connecting end, thereby preventing the spring from entering the periphery of the connecting end. According to such a configuration, since the spring can be moved away from the head of the stem in accordance with the length of the connecting end portion, it is possible to more reliably prevent the spring from being bitten by rubber.

  It is preferable that a ventilation space is formed between the protrusions provided on the side surface of the connection end portion so as to communicate the space around the head and the space around the main body. According to such a configuration, the air discharge resistance is suppressed by the ventilation space formed between the protrusions while the protrusion is provided on the side surface of the connecting end portion. Therefore, the above improvement effect can be obtained while appropriately maintaining the function of the vent plug.

  It is preferable that the projection for regulating the upper end position of the spring extends along the axial direction of the stem. According to such a configuration, the difference in rigidity between the head portion and the trunk portion of the stem can be further reduced, and the bending deformation of the stem can be effectively suppressed. In addition, since the minimum gap between the housing and the connecting end is reduced, the stem is difficult to tilt in the housing, and as a result, the inlet of the exhaust passage is prevented from spreading locally and into the unvulcanized rubber housing. Inflow can be suppressed.

  It is preferable that the plurality of protrusions discontinuous in the circumferential direction are provided with different positions in the axial direction, and when the stem is viewed from the axial direction, the region where the protrusions are provided has an annular shape along the circumferential direction. . In this case, it is possible to ventilate air from the space around the head to the space around the main body through the space between the discontinuous protrusions in the circumferential direction, thereby suppressing air discharge resistance. In addition, since the region where the protrusion is provided is annular along the circumferential direction, it is possible to prevent the unvulcanized rubber flowing into the housing from reaching the spring and prevent the spring from being bitten by rubber.

  Separately from the protrusions that regulate the upper end position of the spring, it is preferable that an annular protrusion along the circumferential direction is provided on the head side of the connecting end. According to such an annular projection, the inflow of unvulcanized rubber into the housing can be suppressed, and the rubber biting of the spring can be prevented. In addition, this annular protrusion is provided on the head side of the connecting end and does not increase the air discharge resistance in the open state of the vent plug, so that the function of the vent plug is properly maintained. The

  The tire manufacturing method according to the present invention includes the steps of setting an unvulcanized tire in the cavity of the tire vulcanization mold described above, and performing vulcanization by applying heat and pressure to the unvulcanized tire. According to such a method, as described above, the bending of the stem can be suppressed and the rubber engagement of the spring can be prevented, so that the malfunction of the vent plug can be prevented and a good tire appearance can be obtained.

1 is a longitudinal sectional view schematically showing an example of a tire vulcanizing mold according to the present invention. Cross-sectional view of vent plug attached to exhaust hole Sectional view showing closed state of vent plug (A) perspective view and (B) AA cross-sectional view of the stem The perspective view of the stem in another embodiment (A) perspective view and (B) BB arrow sectional view of a stem in another embodiment The perspective view of the stem in another embodiment The perspective view of the stem in another embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a cross section of a tire vulcanization mold 10 along a tire meridian cross section, and FIG. 2 shows an enlarged main portion thereof.

  As shown in FIG. 1, the tire vulcanization mold 10 includes a molding surface 1 that is in contact with the outer surface of a tire T set in a cavity 15. The molding surface 1 is provided with a large number of exhaust holes 16 for communicating the inside (cavity 15) of the mold 10 with the outside in order to discharge excess air between the tire and the molding surface 1 during vulcanization molding. It has been. As shown in an enlarged view in FIG. 2, the vent plug 2 is attached to the exhaust hole 16 that opens on the molding surface 1.

  An example of the material for the molding surface 1 is an aluminum material. This aluminum material is a concept including not only a pure aluminum material but also an aluminum alloy. For example, Al-Cu, Al-Mg, Al-Mg-Si, Al-Zn-Mg, Al-Mn Al-Si system is mentioned. The housing 3 and the stem 4 to be described later are preferably made of stainless steel or a steel material typified by S45C, which may be the same metal or different metals.

  The mold 10 of the present embodiment includes a tread mold part 11 that molds a tread part of a tire, side mold parts 12 and 13 that mold a sidewall part of the tire, and a bead ring 14 into which the bead part of the tire is fitted. With. Although not shown, a convex bone portion for forming a groove in the tread surface of the tire is provided on the inner surface of the tread mold portion 11. In FIG. 1, one exhaust hole 16 opened on the inner surface of the tread mold part 11 and one exhaust hole 16 opened on the inner surface of the side mold part 13 are drawn. A large number of exhaust holes 16 that open on the inner surfaces of the mold parts 12 and 13 are provided.

  As shown in FIG. 2, the vent plug 2 includes a cylindrical housing 3 having an exhaust passage 21 therein, a stem 4 that is inserted into the housing 3 and serves as a valve body that opens and closes the exhaust passage 21, and an exhaust passage 21. And a coiled spring 5 that urges the stem 4 toward the cavity 15 so as to be opened. The housing 3 is fitted into the exhaust hole 16 which is a circular hole, and is fixed to the molding surface 1. The opening 31 of the housing 3 has a top surface 31 a facing the cavity 15. The lower end 32 of the housing 3 is formed with a through hole 32a and an inner collar-shaped support 32b.

  The stem 4 has a columnar body 41 inserted into the spring 5 and a head 42 integrally connected to the body 41. A top surface 42 a that faces the cavity 15 and a side surface 42 b that faces the inner surface 31 b of the opening 31 are formed in the head portion 42. When the stem 4 is pushed down by the outer surface of the tire, the head 42 contacts the inner surface 31b of the opening 31 of the housing 3, whereby the exhaust passage 21 is closed and the vent plug 2 is closed as shown in FIG. Although the top surface 42a is disposed flush with the top surface 31a, the present invention is not limited to this.

  The trunk | drum 41 is formed in the column shape extended in the axial direction as a whole. A connecting end 41a connected to the head 42 is provided at one end in the axial direction of the body 41 located on the head 42 side, and at the other end in the axial direction of the body 41 located on the opposite side. A stopper 43 having a diameter larger than that of the through hole 32a is provided. The stem 4 does not come out of the housing 3 due to the action of the stopper 43. The stopper 43 can pass through the through hole 32a by being elastically deformed so as to close the slit 44.

  The connecting end portion 41 a has a larger diameter than the main body portion 41 b of the trunk portion 41 surrounded by the spring 5, and the top surface 42 a of the head portion 42 has a larger diameter than the inner diameter of the housing 3 in which the stem 4 is inserted. is there. That is, the diameter D1 of the connecting end portion 41a and the diameter D2 of the main body portion 41b satisfy the relationship of D1> D2, and the diameter D3 of the top surface 42a and the inner diameter D4 of the housing 3 satisfy the relationship of D3> D4. The inner diameter D5 is the inner diameter of the spring 5 that is incorporated in the housing 3 and receives a compression action. Although there is a case where D5> D1 in the process in which the vent plug 2 repeats opening and closing, the spring 5 does not cover the connecting end 41a due to the action of the projection 61 described later.

  In FIG. 2, the exhaust path 21 is open, and the vent plug 2 is in an open state. While the vent plug 2 is in the open state, the air in the cavity 15 is discharged to the outside of the mold 10 through the exhaust passage 21 as the outer surface of the tire approaches the molding surface 1. The exhaust passage 21 is formed so as to pass from the periphery of the head portion 42 (between the inner surface 31b and the side surface 42b), the periphery of the connection end portion 41a, the periphery of the main body portion 41b, and the through hole 32a. Since the opening of the housing 3 and the head 42 are circular as viewed from the axial direction, the inlet of the exhaust passage 21 is opened in a ring shape.

  A plurality of (four in this embodiment) projections 61 are provided on the side surface of the coupling end portion 41a, and the upper end position of the spring 5 is regulated by all of the projections 61. As shown in FIG. 4, the protrusions 61 are intermittently arranged at four locations in the circumferential direction around the axis. The diameter D6 including the protrusion 61 is smaller than the inner diameter D4 of the housing 3 and larger than the inner diameter D5 of the spring 5, and satisfies the relationship D4> D6> D5. The spring 5 surrounds the main body 41b of the body 41 and is interposed between the protrusion 61 and the support 32b to urge the stem 4.

  Since the trunk portion 41 is connected to the head portion 42 via the connecting end portion 41a having a diameter larger than that of the main body portion 41b, the difference in rigidity between the head portion 42 and the trunk portion 41 is relatively small. As a result, the stem 4 The bending deformation of can be appropriately suppressed. In addition, since the spring 5 is always moved away from the molding surface 1 by the protrusion 61, even if unvulcanized rubber flows into the housing 3, it is difficult to reach the spring 5, and the vent plug 2 caused by the rubber biting of the spring 5 is difficult. Malfunctions can be prevented. The inflow rubber in the housing 3 is easy to be removed together with the tire 5 when it is attached to the tire when the tire after the vulcanization molding is removed if the spring 5 is not engaged with the rubber.

  In the present embodiment, the head portion 42 of the stem 4 is formed in a truncated cone shape whose diameter increases toward the cavity 15, and the inner surface 31 b of the opening 31 of the housing 3 is a tapered surface whose diameter increases toward the cavity 15. Is formed. The connecting end 41a is formed in a cylindrical shape extending in the axial direction with the thickness of the bottom surface of the truncated cone. According to such a configuration, the difference in rigidity between the head portion 42 and the trunk portion 41 can be suitably reduced, which is convenient for suppressing the bending deformation of the stem 4.

  In the present embodiment, a protrusion 61 that regulates the upper end position of the spring 5 is provided on the main body 41b side (lower side in FIG. 3) of the connecting end 41a, whereby the spring 5 enters the periphery of the connecting end 41a. Is blocked. Although a protrusion may be provided on the central portion of the connecting end portion 41a or the head portion 42 side, the spring 5 is restricted by the protrusion 61 provided on the main body portion 41b side as described above, thereby increasing the length of the connecting end portion 41a. Accordingly, the spring 5 can be moved away from the head portion 42, so that the rubber biting of the spring 5 can be prevented more reliably.

  Between the protrusions 61 provided on the side surface of the connecting end portion 41a, a ventilation space 45 is formed that communicates the space around the head portion 42 with the space around the main body portion 41b. For this reason, the discharge of air from the cavity 15 to the outside is not hindered by the protrusion 61, and the function of the vent plug 2 can be appropriately maintained while suppressing the air discharge resistance. On the other hand, when the protrusion 61 is provided in an annular shape along the circumferential direction, the air discharge resistance tends to increase in the exhaust passage 21, particularly around the connection end portion 41 a.

  The modification of the protrusion provided in the side surface of the connection end part 41a is shown in FIGS. Since these are the same configurations and operations as those of the above-described embodiment except for the configurations described below, common points will be omitted and differences will be mainly described. Moreover, the same code | symbol is attached | subjected about the structure same as the already-described structure, and the overlapping description is abbreviate | omitted.

  In the example of FIG. 5, a plurality of protrusions 62 are provided on the side surface of the connecting end portion 41 a, and the upper end position of the spring 5 (not shown in FIG. 5, the same applies to FIGS. 6 to 8) is regulated by all of the protrusions 62. . The protrusions 62 are intermittently disposed at a plurality of circumferential positions (four positions in the present embodiment) similarly to the protrusions 61 of FIG. 4, and each extends along the axial direction of the stem 4. According to such a protrusion 62, the difference in rigidity between the head portion 42 and the trunk portion 41 can be further reduced, and the bending deformation of the stem 4 can be effectively suppressed. In order to enhance the effect of suppressing the bending deformation, it is preferable to extend the protrusion 62 to the vicinity of the head 42.

  Between the protrusions 62, a ventilation space 45 is formed along the axial direction of the stem 4, and the ventilation from the space around the head portion 42 to the space around the main body portion 41b can be performed. Air discharge resistance is suppressed. Further, since the minimum gap between the housing 3 and the connecting end portion 41a is reduced in the axial direction, the stem 4 is difficult to tilt in the housing 3. As a result, it is possible to prevent the inlet of the exhaust passage 21 from spreading locally, and to suppress the inflow of unvulcanized rubber into the housing 3. As a result, the vent plug 2 caused by the rubber engagement of the spring 5 can be suppressed. Malfunctions can be prevented.

  In the example of FIG. 6, a plurality of protrusions 63 and 64 are provided on the side surface of the connecting end portion 41 a, and the upper end position of the spring 5 is regulated by a part of the protrusions 63 and 64 (protrusion 64 in this embodiment). The protrusions 63 and 64 are intermittently disposed at a plurality of locations in the circumferential direction (four locations in the present embodiment), and are separated in the axial direction of the stem 4. That is, protrusions 63 and 64 that are discontinuous in the circumferential direction are provided with different axial positions. Further, the protrusions 63 and 64 are displaced from each other in the circumferential direction so as to have a complementary shape. When the stem 4 is viewed from the axial direction, the region where the protrusion is provided as shown in FIG. It becomes annulus along.

  According to such a configuration, the ventilation space 45 is formed between the protrusions 63, between the protrusions 63 and 64, and between the protrusions 64, and passes through the space around the head portion 42 from the space around the head portion 42. Since air can be ventilated to the surrounding space, air discharge resistance is suppressed. In addition, since the region where the protrusions are provided has an annular shape along the circumferential direction, even if unvulcanized rubber flows into the housing 3, the inflow rubber does not easily reach the spring 5, and the rubber engagement of the spring 5 occurs. Due to this, it is possible to prevent the malfunction of the vent plug 2.

  In the example of FIG. 7, a plurality of protrusions 65 and 66 are provided on the side surface of the connecting end portion 41 a, and the upper end position of the spring 5 is regulated by a part of the protrusions 65 and 66 (in this embodiment, the protrusion 66). The protrusion 65 is an annular protrusion along the circumferential direction, and is provided on the head 42 side (upper side in FIG. 7) of the connection end 41 a separately from the protrusion 66. The protrusion 66 has the same configuration as the protrusion 61 of FIG. 4, but may have another form as long as the upper end position of the spring 5 can be regulated.

  In such a configuration, the annular protrusion 65 prevents the unvulcanized rubber from flowing into the housing 3. Moreover, since the protrusion 65 is disposed on the side of the head 42 of the connecting end portion 41a, for example, at a height facing the inner surface 31b of the opening 31 in the opened state of the vent plug 2, the protrusion 65 causes the air to flow. Therefore, the vent plug 2 function can be appropriately maintained. Nevertheless, since the spring 5 is always moved away from the molding surface 1 by the projection 66, the rubber biting of the spring 5 can be effectively prevented.

  In the example of FIG. 8, one protrusion 67 is provided on the side surface of the connecting end 41 a, and the upper end position of the spring 5 is regulated by the protrusion 67. Since the projection 67 is provided in a spiral shape along the circumferential direction, and a spiral ventilation space 45 is formed between the projections 67, the projection 67 passes through the space around the head portion 42 b from the space around the head 42. The air can be ventilated into the space, and air discharge resistance can be suppressed.

  The shape of the protrusion provided on the side surface of the connecting end portion 41a may be other than the above as long as the upper end position of the spring 5 can be regulated, and other point-like protrusions instead of or in addition to the protrusion exemplified in the above-described embodiment. It is possible to employ protrusions that extend continuously or intermittently in the circumferential direction, or protrusions that extend continuously or intermittently in the axial direction.

  The method of manufacturing a tire using the mold 10 includes a step of setting an unvulcanized tire in the cavity 15 of the mold 10 and performing vulcanization by applying heat and pressure to the unvulcanized tire. The tire is expanded and deformed by expansion of a rubber bag called a bladder, and the outer surface of the tire presses against the molding surface 1. In the process, air between the tire and the molding surface 1 is discharged to the outside through the exhaust path 21 of the vent plug 2. At this time, the space in the exhaust hole 16 may be sucked with a suction machine to improve the exhaust performance.

  The tire vulcanization mold described above is the same as a normal tire vulcanization mold except that the vent plug attached to the exhaust hole is configured as described above, and any conventionally known shape, material, mechanism, etc. Can also be employed in the present invention.

  The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention. In the above-described embodiment, the mold structure is provided with a tread mold part and a pair of side mold parts, but the present invention is not limited to this. For example, the mold structure is vertically divided into two at the center part of the tread mold part. Also applicable to mold structures.

DESCRIPTION OF SYMBOLS 1 Molding surface 2 Vent plug 3 Housing 4 Stem 5 Spring 10 Tire vulcanization mold 15 Cavity 16 Exhaust hole 21 Exhaust passage 31 Opening part 41 Body part 41a Main part 41b Main part 42 Head part 45 Ventilation space 61 Protrusion 62 Protrusion 63 Projection 64 Projection 65 Projection 66 Projection 67 Projection

Claims (7)

In a tire vulcanization mold comprising a molding surface in contact with an outer surface of a tire set in a cavity, and a vent plug attached to an exhaust hole opened in the molding surface,
The vent plug includes a cylindrical housing having an exhaust passage therein, a stem that is inserted into the housing and serves as a valve body that opens and closes the exhaust passage, and the stem is inserted into the cavity so as to open the exhaust passage. And a coiled spring that urges toward
The stem has a columnar body portion that is inserted into the spring, and a head portion that closes the exhaust passage by contacting an inner surface of the opening portion of the housing,
The connecting end of the trunk connected to the head is larger in diameter than the main body of the trunk surrounded by the spring, and the top surface of the head is inserted with the stem. Larger than the inner diameter of the housing,
One or more protrusions are provided on the side surface of the connecting end, and the upper end position of the spring is regulated by all or a part of the protrusions.   2. The tire additive according to claim 1, wherein the protrusion that regulates the upper end position of the spring is provided on the main body side of the connecting end, thereby preventing the spring from entering the periphery of the connecting end. Sulfur mold.   The ventilation space which connects the space around the said head and the space around the said main-body part between the said protrusions provided in the side surface of the said connection end part is formed. Tire vulcanization mold.   The tire vulcanization mold according to any one of claims 1 to 3, wherein the protrusion that regulates an upper end position of the spring extends along an axial direction of the stem.   The plurality of protrusions that are discontinuous in the circumferential direction are provided with different positions in the axial direction, and when the stem is viewed from the axial direction, the region where the protrusions are provided has an annular shape along the circumferential direction. The tire vulcanization mold according to any one of? 3.   The annular projection along the circumferential direction is provided on the head side of the connecting end portion separately from the projection that regulates the upper end position of the spring. Tire vulcanization mold.   Manufacturing of a tire including a step of setting an unvulcanized tire in the cavity of the tire vulcanization mold according to any one of claims 1 to 6 and subjecting the unvulcanized tire to heating and pressurizing. Method.

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