JP2020066121A - Vent piece, tire vulcanization die, and tire manufacturing method - Google Patents

Abstract

To provide a vent piece capable of suppressing generation of spew clogging, and to provide a tire vulcanization die and a tire manufacturing method thereof.SOLUTION: A vent piece 2 comprises a cylindrical holder 3, and a cylindrical chuck 4 inserted inside the holder 3 in a nesting state. The holder 3 is provided with an inner peripheral surface 32 tilted in such a manner that an inner diameter gradually increases toward a cavity. The chuck 4 is provided with an outer peripheral surface 41 tilted so as to correspond to the inner peripheral surface 32 of the holder 3, and a division part provided in at least one portion in a circumferential direction. The chuck 4 is constituted so as to be displaceable in an axial direction between a first position at which the inner peripheral surface 32 of the holder 3 is applied to the outer peripheral surface 41 of the chuck 4, and a second position at which the outer peripheral surface 41 of the chuck 4 is separated from the inner peripheral surface of the holder 3.SELECTED DRAWING: Figure 5

Description

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

  Conventionally, in a tire vulcanizing mold, a large number of exhaust holes are provided on a molding surface for molding an outer surface of a tire. The exhaust hole communicates with the inside and the outside of the mold and discharges air between the outer surface of the tire and the molding surface during vulcanization molding, thereby preventing the occurrence of dent scratches called bare. Since rubber on the outer surface of the tire flows into the exhaust holes during vulcanization molding, many rubber protrusions called spews are formed on the outer surface of the vulcanized tire.

  As described in Patent Document 1, it is known to fit a cylindrical vent piece into the exhaust hole for the purpose of adjusting the size of the spew. Further, when the vulcanized tire is released from the mold, so-called spew breakage may occur, in which spew is cut in the middle due to frictional resistance with the inner surface of the vent piece. When the spew is broken, the separated spew causes the vent piece to be clogged, which hinders the discharge of air.

  Patent Document 2 describes a tire vulcanizing mold having a vent plug attached to an exhaust hole. However, this is a technique relating to a vent plug that does not generate spews, and does not suggest a solution to the problem of spew breakage when using the vent piece as described above.

JP, 2008-30402, A JP, 2009-255485, A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a vent piece, a tire vulcanizing mold, and a tire manufacturing method capable of suppressing the occurrence of spew breakage.

  The above object can be achieved by the present invention as described below. That is, the vent piece according to the present invention is a vent piece that is attached to an exhaust hole that is opened on the molding surface of a tire vulcanizing mold, and has a cylindrical holder and a cylindrical shape that is nested inside the holder. The chuck has an inner peripheral surface inclined so that the inner diameter gradually increases toward the cavity, and the chuck has an outer peripheral surface inclined to correspond to the inner peripheral surface of the holder. And a split portion provided at at least one position in the circumferential direction, wherein the chuck has a first position in which the inner peripheral surface of the holder is directed to the outer peripheral surface of the chuck, and the inside of the holder. It is configured to be axially displaceable between a second position where the outer peripheral surface of the chuck is separated from the peripheral surface.

  With this configuration, when the vulcanized tire is released from the mold, the chuck is displaced to the second position by the frictional resistance between the inner surface of the vent piece (that is, the inner surface of the chuck) and the spew. At the second position, since the outer peripheral surface of the chuck is separated from the inner peripheral surface of the holder, the chuck can open the split portion to expand the diameter. This reduces the resistance when pulling out the spew from the vent piece, and suppresses the occurrence of spew breakage.

  It is preferable that the vent piece has an urging member that urges the chuck toward the first position. According to this structure, the chuck can be arranged at the first position by the biasing force of the biasing member.

  It is preferable that an end portion of the chuck farther from the cavity is provided with a retaining portion that prevents the chuck from coming out of the holder toward the cavity. This can prevent the chuck from falling off.

  It is preferable that the chuck has a recess on the inner peripheral surface thereof. According to this structure, since the bulge is formed on the spew, the spew can be pulled by using the bulge in the trimming step after the vulcanization step.

  A tire vulcanizing mold according to the present invention comprises the molding surface in contact with the outer surface of a tire set in a cavity, and the vent piece mounted in the exhaust hole opening in the molding surface. is there. With this configuration, when the vulcanized tire is released from the mold, the chuck can be displaced and the diameter thereof can be increased as described above, and the occurrence of spew breakage can be suppressed.

  The method for manufacturing a tire according to the present invention comprises a step of setting an unvulcanized tire in a cavity of a tire vulcanizing mold equipped with the vent piece, and performing vulcanization by applying heat and pressure to the unvulcanized tire. It includes. According to such a method, when the vulcanized tire is released from the mold, the chuck can be displaced and the diameter thereof can be expanded as described above, and the occurrence of spew breakage can be suppressed.

  The tire manufacturing method according to the present invention, an unvulcanized tire is set in a cavity of a tire vulcanizing mold provided with the vent piece provided with a concave portion on the inner peripheral surface of the chuck, and the unvulcanized tire is It includes a step of performing vulcanization by applying heat and pressure, and a trimming step of cutting out the spews protruding from the outer surface of the vulcanized tire, and in the trimming step, the outer surface of the vulcanized tire is guided. The tire may be rotated with the cutter blade brought close to the cutter blade, and the swelling portion formed by the recess may be hooked on the guide to pull the spew, and the spew may be cut by the cutter blade. This prevents the spew from collapsing, makes it easier to maintain the posture of the spew during cutting, and makes it possible to make the cutting marks inconspicuous by cutting while pulling the spew.

A longitudinal cross-sectional view schematically showing an example of a tire vulcanizing mold provided with a vent piece according to the present invention Cross-sectional view of vent piece installed in exhaust hole The figure which looked at the vent piece of FIG. 2 along the axial direction. Diagram explaining the split structure of the chuck Sectional drawing which shows the vent piece at the time of vulcanization molding Sectional drawing of the vent piece in another embodiment. Sectional drawing of the vent piece in another embodiment. Figure showing how to cut out a spew with a bulge A perspective view showing an example of a guide used in a trimming process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a cross section of a tire vulcanizing mold 10 (hereinafter, may be simply referred to as “mold 10”) along a tire meridian section. The mold 10 is in a mold closed state. The tire T is set with the tire width direction facing up and down. In FIG. 1, the left direction is the tire radial direction outer side, and the right direction is the tire radial direction inner side. 2 is an enlarged view of a main part of FIG. 1, and corresponds to a cross section taken along the line AA of FIG. In FIG. 2, the upper direction is the tire radial direction inner side, and the lower direction is the tire radial direction outer side. FIG. 3 is a view of the vent piece 2 seen from the cavity 15 side along the axial direction.

  The mold 10 includes a molding surface 1 that contacts the outer surface of the tire T set in the cavity 15. The molding surface 1 is provided with an exhaust hole 16 that communicates the inside (cavity 15) of the mold 10 with the outside. At the time of vulcanization molding, air between the tire T and the molding surface 1 is discharged through the exhaust holes 16. As shown in an enlarged manner in FIG. 2, the vent piece 2 is attached to the exhaust hole 16 that opens at the molding surface 1.

  An example of the material of the molding surface 1 is an aluminum material. This aluminum material is a concept that includes not only pure aluminum-based materials but also aluminum alloys. For example, Al-Cu-based, Al-Mg-based, Al-Mg-Si-based, Al-Zn-Mg-based, Al-Mn-based. , Al-Si type. A holder 3 and a chuck 4 which will be described later and which constitute the vent piece 2 are preferably formed of stainless steel or a steel material typified by S45C, and these may be the same kind of metal or different kinds of metal.

  The mold 10 includes a tread mold portion 11 for molding a tread portion of a tire, side mold portions 12 and 13 for molding a sidewall portion of a tire, and bead rings 14 and 14 to which bead portions of a tire are fitted. Prepare The molding surface 1 includes the inner surface of the tread mold portion 11 and the inner surfaces of the side mold portions 12 and 13. Although not shown in the drawings, a convex bone portion for forming a groove on the tread surface of the tire is provided on the inner surface of the tread mold portion 11. In FIG. 1, only one exhaust hole 16 opened on the inner surface of the tread mold portion 11 is drawn, but in reality, a large number of exhaust holes opened on the inner surfaces of the tread mold portion 11 and the side mold portions 12, 13 are provided. It is provided.

  As shown in FIGS. 2 and 3, the vent piece 2 has a cylindrical holder 3 and a cylindrical chuck 4 that is inserted inside the holder 3 in a nested manner. The holder 3 is fixed to the molding surface 1. More specifically, the holder 3 is press-fitted into the exhaust hole 16 by an interference fit. Therefore, the outer peripheral surface 31 of the holder 3 is in close contact with the inner peripheral surface of the exhaust hole 16. The holder 3 has an inner peripheral surface 32 that is inclined so that the inner diameter thereof gradually increases toward the cavity 15. The inner peripheral surface 32 is formed in a tapered shape. In this embodiment, the top surface 33 of the holder 3 is arranged flush with the molding surface 1.

  The chuck 4 has an outer peripheral surface 41 that is inclined so as to correspond to the inner peripheral surface 32 of the holder 3. The outer peripheral surface 41 is inclined so that the outer diameter gradually increases toward the cavity 15. The outer peripheral surface 41 is formed in a tapered shape having the same slope as the inner peripheral surface 32 of the holder 3. The inner surface of the vent piece 2 is formed by the inner surface of the chuck 4 (that is, the inner peripheral surface 42). Therefore, the chuck 4 is in contact with the spew 9 (see FIG. 5) formed of the rubber flowing into the vent piece 2. The inner peripheral surface 42 extends along the axial direction with a constant inner diameter.

  As shown in FIG. 3, the chuck 4 has dividing portions 44, 44 provided at two locations in the circumferential direction. The chuck 4 has a split structure as shown in FIG. 4A, and is composed of two split pieces 4A and 4B that are arcuate when viewed in the axial direction. However, the present invention is not limited to this, and the chuck 4 may have a divided portion at at least one position in the circumferential direction. Therefore, for example, a three-divided structure as shown in FIG. 4 (B) or a one-divided structure as shown in FIG. 4 (C) may be used. However, in performing the diameter expansion operation described below, it is preferable to have the dividing portions 44 at at least two locations in the circumferential direction.

  The chuck 4 is configured to be axially displaceable between the first position shown in FIGS. 2 and 5 (A) and the second position shown in FIG. 5 (B). The chuck 4 can move relative to the holder 3 along its axial direction. The chuck 4 in the second position projects more toward the cavity 15 than the chuck 4 in the first position. At the first position, as shown in FIG. 5A, the inner peripheral surface 32 of the holder 3 is in contact with the outer peripheral surface 41 of the chuck 4. At the second position, as shown in FIG. 5B, the outer peripheral surface 41 of the chuck 4 is separated from the inner peripheral surface 32 of the holder 3.

  In the first position, since the inner peripheral surface 32 is directed to the outer peripheral surface 41, the divided portions 44, 44 of the chuck 4 are closed, and the divided pieces 4A and 4B are continuously connected to form an annular shape. (FIG. 4 (A) left side). The top surface 43 of the chuck 4 is arranged flush with the top surface 33 of the holder 3. On the other hand, at the second position, the outer peripheral surface 41 is separated from the inner peripheral surface 32, and a gap is created between them, so that the chuck 4 can open the split portions 44, 44 and expand the diameter. (Right side of FIG. 4 (A)). The top surface 43 of the chuck 4 is arranged closer to the cavity 15 than the top surface 33 (and the molding surface 1) of the holder 3.

  During vulcanization molding, a spew 9 is formed inside the vent piece 2 as shown in FIG. The spew 9 is pulled out from the vent piece 2 when the vulcanized tire is demolded. The occurrence of spew breakage is a concern when the frictional resistance between the inner surface (that is, the inner peripheral surface 42) of the vent piece 2 and the spew 9 is large, and when the frictional resistance is small, there is little concern about spewing. According to this vent piece 2, when the frictional resistance between the inner surface of the vent piece 2 and the spew 9 is large, the chuck 4 is displaced to the second position by the frictional resistance, and the spew is moved to the second position as shown in FIG. The diameter of the chuck 4 is expanded according to the operation of pulling out the chuck 9. As a result, the resistance when pulling out the spew 9 is reduced, and the occurrence of spew breakage is suppressed.

  The vent piece 2 has a spring 5 as a biasing member that biases the chuck 4 toward the first position. The spring 5 is arranged between the inner collar-shaped narrowing portion 34 formed on the holder 3 and the collar-shaped retaining portion 45 formed on the chuck 4, and is arranged in a direction away from the cavity 15 (anti-cavity). 15 side). As a result, the chuck 4 is arranged at the first position by the urging force of the spring 5 when the external force does not act on the vent piece 2 after the spew 9 is pulled out. The biasing member is not limited to such a coiled spring 5 as long as it has such a function. It is also possible to omit the biasing member, in which case the chuck 4 is pushed by the unvulcanized tire and placed in the first position.

  As shown in FIG. 5B, the retaining portion 45 prevents the chuck 4 from coming out of the holder 3 toward the cavity 15, and prevents the chuck 4 from falling off. The retaining portion 45 is provided at the end of the chuck 4 which is remote from the cavity 15. In the present embodiment, the chuck 4 is formed longer than the holder 3 in the axial direction, and the end portion provided with the retaining portion 45 always projects from the holder 3 to the side opposite to the cavity 15. The outer diameter of the retaining portion 45 is larger than the inner diameter of the throttle portion 34. Further, the outer diameter of the body portion 46 of the chuck 4 inserted through the narrowed portion 43 is smaller than the inner diameter of the narrowed portion 34.

  The tire manufacturing method using the mold 10 is a step of setting an unvulcanized tire in the cavity 15 of the mold 10 and subjecting the unvulcanized tire to heating and pressurization for vulcanization (vulcanization step). including. The tire is expanded and deformed by the expansion of a rubber bag called a bladder, and the outer surface thereof is pressed against the molding surface 1. In the process, the air between the tire and the molding surface 1 is discharged to the outside through the vent piece 2, and the spew 9 is formed inside the vent piece 2 as shown in FIG. At this time, the space inside the exhaust hole 16 may be sucked by a suction device to improve the exhaust performance. When demolding the vulcanized tire, the chuck 4 expands while being axially displaced as shown in FIG. 5B, so that the occurrence of spew breakage can be suppressed.

  The tire manufacturing method may include a step (trimming step) of cutting off the spew 9 protruding from the outer surface of the vulcanized tire for the purpose of improving the tire appearance. In the trimming step, the tire is relatively rotated while the cutter blade is brought close to the outer surface (eg, tread surface) of the vulcanized tire, and the root of the spew 9 is cut along the tire circumferential direction. At this time, if the spew 9 touching the cutter blade falls and the posture of the spew 9 collapses, the spew 9 may not be cut from the root, and the remnant scars remaining in a stump shape may be conspicuous.

  In the present embodiment, the vent piece 2 as described above is attached to the exhaust hole 16 that opens on the inner surface of the tread mold portion 11 as the molding surface 1, but instead of or in addition to this, the side mold portion 12 is provided. (And / or the side mold part 13) can also be attached to an exhaust hole opened on the inner surface.

  In the present embodiment, the mold structure including the tread mold section 11 and the pair of side mold sections 12 and 13 has been exemplified, but the present invention is not limited to this, and for example, the tread mold section is vertically divided into two parts. It may be a mold structure.

  6 and 7 show modified examples of the vent piece 2. Since these have the same configuration and operation as those of the above-described embodiment, except for the configuration described below, common points will be omitted and differences will be mainly described. Further, the same components as those already described are designated by the same reference numerals, and duplicate description will be omitted.

  In the example of FIG. 6, the inner peripheral surface 42 of the chuck 4 is inclined so that the inner diameter gradually decreases toward the cavity 15. Therefore, the spew 9 is formed in a tapered shape that gradually becomes thicker toward the tip thereof. According to this configuration, when the vulcanized tire is released from the mold, the frictional resistance between the inner surface (that is, the inner peripheral surface 42) of the vent piece 2 and the spew 9 becomes large, and the chuck 4 is secured along the axial direction. And can be displaced from the first position to the second position.

  In the example of FIG. 7, a concave portion 47 is provided on the inner peripheral surface 42 of the chuck 4. Therefore, the swelling portion 91 corresponding to the recess 47 is formed on the spew 9. The bulging portion 91 has a rounded shape, and is formed in a spherical shape in the present embodiment. Since the swelling portion 91 is formed on the spew 9, the friction resistance between the inner surface (that is, the inner peripheral surface 42) of the vent piece 2 and the spew 9 becomes large when the vulcanized tire is released from the mold. However, by displacing and expanding the diameter of the chuck 4 as described above, the spew 9 can be pulled out without trouble, and the occurrence of spew breakage can be suppressed.

  As shown in FIG. 8, in the trimming step of cutting off the spew 9 having the bulged portion 91, the tire is rotated while the guide 6 and the cutter blade 7 are brought close to the outer surface Ts of the vulcanized tire, It is preferable to cut the spew 9 with the cutter blade 7 while hooking the bulge 91 formed by the recess 47 on the guide 6 and pulling the spew 9. This prevents the spew 9 from falling down, and makes it easier to maintain the posture of the spew 9 at the time of cutting, and by cutting the spew 9 while pulling it, the cut mark becomes inconspicuous. In addition, by reducing the size of the stump-shaped excision mark, an effect of reducing rolling resistance can be expected.

  The guide 6 is formed in a comb shape as shown in FIG. When the tire rotates relative to the guide 6, the bulging portion 91 of the spew 9 that has entered the groove 61 is guided to the outer peripheral side, whereby the spew 9 is pulled. In order to properly exhibit such an action, it is preferable that the bulging portion 91 is formed at the center of the spew 9 or on the tip side of the spew 9. Further, when the chuck 4 is in the first position, the distance D (see FIG. 7) from the molding surface 1 to the concave portion 47 is preferably 5 mm or more. The guide 6 is not limited to being formed separately from the cutter blade 7, and may be integrated with the cutter blade 7.

  The tire vulcanizing mold described above is the same as a normal tire vulcanizing mold except that the vent piece attached to the exhaust hole is configured as described above, and has any conventionally known shape, material, mechanism, or the like. Can also be adopted in the present invention.

  The present invention is not limited to the embodiments described above, and various improvements and modifications can be made without departing from the spirit of the present invention.

1 Molding surface 2 Bent piece 3 Holder 4 Chuck 5 Spring (an example of a biasing member)
6 Guide 7 Cutter Blade 9 Spew 10 Tire Vulcanizing Mold 15 Cavity 16 Exhaust Hole 31 Holder Outer Surface 32 Holder Inner Surface 41 Chuck Outer Surface 42 Chuck Inner Surface 44 Split Part 45 Detachment Part 47 Recess 91 Bulge

Claims (7)

In the vent piece attached to the exhaust hole that opens on the molding surface of the tire vulcanization mold,
A tubular holder, and a tubular chuck inserted inside the holder in a nested manner,
The holder has an inner peripheral surface inclined so that the inner diameter gradually increases toward the cavity,
The chuck has an outer peripheral surface inclined so as to correspond to the inner peripheral surface of the holder, and a dividing portion provided at at least one position in the circumferential direction,
The chuck has a first position in which the inner peripheral surface of the holder is directed to the outer peripheral surface of the chuck and a second position in which the outer peripheral surface of the chuck is separated from the inner peripheral surface of the holder. , A vent piece characterized by being configured to be displaceable in the axial direction.   The vent piece according to claim 1, further comprising a biasing member that biases the chuck toward the first position.   The vent piece according to claim 1 or 2, wherein an end portion of the chuck farther from the cavity is provided with a retaining portion that prevents the chuck from coming out of the holder toward the cavity.   The vent piece according to any one of claims 1 to 3, wherein a concave portion is provided on an inner peripheral surface of the chuck.   Tire vulcanization provided with the said shaping | molding surface which contacts the outer surface of the tire set to the cavity, and the vent piece of any one of Claims 1-4 mounted in the said exhaust hole opened in the said shaping | molding surface. Mold.   A step of setting an unvulcanized tire in a cavity of a tire vulcanizing mold provided with the vent piece according to any one of claims 1 to 4, and performing vulcanization by applying heat and pressure to the unvulcanized tire. A method for manufacturing a tire including: A vulcanization step in which an unvulcanized tire is set in the cavity of a tire vulcanizing mold provided with the vent piece according to claim 4, and the unvulcanized tire is heated and pressed for vulcanization;
Including a trimming step of cutting off the spews protruding from the outer surface of the vulcanized tire,
In the trimming step, the tire is rotated in a state where a guide and a cutter blade are brought close to the outer surface of the vulcanized tire, and the bulging portion formed by the recess is hooked on the guide to pull the spew, A method for manufacturing a tire, in which spews are cut off with the cutter blade.

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