JP2017105064A - Tire vulcanization mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire vulcanization mold capable of removing rubber invading between a housing of a vent plug and a stem. SOLUTION: A vent plug is provided with a housing 40 which is tubular and has a vent hole from the inside of the mold to the outside of the mold on the inner diameter side, and a stem 50 which is inserted into the inner diameter side of the housing 40 to open and close the vent. Molded along the contact surface 44 in a tire vulcanization mold in which the surface of the housing 40 forming the ventilation holes, which is continuous from the molding surface, is the contact surface 44 that comes into contact with the stem 50 when the ventilation holes are closed. A rubber guide groove 47 extending from the surface 44 in the depth direction of the housing 40 is provided. [Selection diagram] Fig. 4

Description

  The present invention relates to a tire vulcanization mold.

  A tire vulcanization molding die used for vulcanization molding of a pneumatic tire is provided with a plurality of plug attachment holes that allow communication between the inside of the die and the outside of the die. A vent plug having a vent hole is fitted in these plug mounting holes. During vulcanization molding, air inside the mold escapes to the outside of the mold through the vent hole of the vent plug.

  By the way, some vent plugs consist only of a cylindrical member, and in the vent plug, a space on the inner diameter side of the cylindrical member is a vent hole. When vulcanization molding is performed using a vent plug consisting only of a cylindrical member, air inside the mold escapes to the outside of the mold through the vent hole of the vent plug, and then fluid rubber enters the vent hole. invade. As a result, unnecessary protrusions (spooes) made of rubber that has entered the air holes are formed on the surface of the pneumatic tire after vulcanization molding.

  In order to prevent the occurrence of spew, a vent plug including a cylindrical housing having a space on the inner diameter side as a ventilation hole and a stem inserted into the ventilation hole may be used (see, for example, Patent Documents 1 to 3). In this vent plug, the stem is always urged to the inside of the mold and the air vent is open, but when the rubber reaches the vent plug during vulcanization molding and pushes the stem from the inside of the mold, the stem Close the housing vent. Therefore, it is difficult for rubber to enter the ventilation hole, and spew is hardly generated.

Japanese Patent Laying-Open No. 2015-20297 JP, 2014-210356, A JP 2014-58046 A

  However, even when a vent plug including a housing and a stem is used, depending on the direction in which the rubber approaches the vent plug, the rubber may enter between the housing and the stem. In that case, when the pneumatic tire is taken out from the tire vulcanization mold after the vulcanization molding is finished, the molded rubber that has penetrated between the housing and the stem is torn off, and the one between the housing and the stem is broken. Rubber may remain in the part. Then, the stem cannot block the vent hole, and the vent plug does not function.

  Therefore, an object of the present invention is to provide a tire vulcanization mold that can remove rubber that has entered between a housing and a stem of a vent plug.

  The tire vulcanization mold according to the embodiment includes a molding member having a molding surface for molding a tire surface, a plug mounting hole provided in the molding member and communicating between the inside of the mold and the outside of the mold, and the plug mounting hole. A vent plug fitted to the housing, the vent plug being cylindrical and having a vent hole on the inner diameter side from the inside of the mold to the outside of the mold, and the vent hole inserted into the inner diameter side of the housing. In a tire vulcanization molding die comprising a stem that opens and closes, and a surface that continues from the molding surface of the housing that forms the vent hole is a contact surface that contacts the stem when the vent hole is closed A rubber guide groove extending from the molding surface in the depth direction of the housing is provided along the contact surface.

  In the tire vulcanization molding die according to the embodiment, the rubber that has entered the guide concave groove and is molded there is not easily torn off from the tire surface. Therefore, when the pneumatic tire is taken out from the tire vulcanization mold, the rubber that has entered between the housing and the stem is removed together with the pneumatic tire.

Sectional drawing of the axial direction of the tire vulcanization molding die 10 of embodiment. The sectional view of the axial direction of vent plug 30 of an embodiment. The figure which looked at the housing 40 of the vent plug 30 of embodiment from the metal mold | die inside. The fragmentary sectional view in AA of Drawing 3 of housing 40 in which stem 50 in an embodiment was inserted. FIG. 5 is an enlarged cross-sectional view of the vicinity of a circumferential groove 48 in FIG. The figure which looked at the guide ditch | groove 147 of the example of a change from the metal mold | die inside. Sectional drawing of the vent plug axial direction vicinity of the circumferential groove 148 of the example of a change.

  This embodiment will be described with reference to the drawings. The drawings may be exaggerated for the purpose of explanation.

  FIG. 1 shows a tire vulcanization mold 10 according to this embodiment. The tire vulcanization mold 10 includes a plurality of sectors 12 arranged on the circumference, a pair of side plates 14 provided on both sides in the axial direction of the circumference formed by the plurality of sectors 12, and a pair of bead rings. 16. The sector 12, the side plate 14, and the bead ring 16 are molding members for molding a pneumatic tire, and the inner surface of these molds is a molding surface 18 for molding the tire surface. The plurality of sectors 12 mainly molds the tire tread, the pair of side plates 14 molds the tire side, and the pair of bead rings 16 molds the tire bead. The material of the sector 12 is not limited, but is, for example, aluminum or an aluminum alloy (for example, an Al—Cu, Al—Mg, Al—Mn, or Al—Si alloy). Moreover, although the material of the side plate 14 and the bead ring 16 is not limited, For example, it is steel materials, such as a general structural rolled steel material (for example, SS400). The material of the side plate 14 and the material of the bead ring 16 may be the same or different.

  A plurality of plug mounting holes 20 are provided in the sector 12 and the side plate 14 which are molding members. The plug attachment hole 20 is a hole having a circular cross section and extending from the inside of the mold toward the outside of the mold. The plug attachment holes 20 are opened on the molding surface 18 and the outer surface of the mold. Therefore, the inside of the mold communicates with the outside of the mold through the plug mounting hole 20. Usually, the plug attachment hole 20 is opened in the molding surface 18 where air remains until the end of the vulcanization molding. A vent plug 30 is fitted in the plug mounting hole 20.

  As shown in FIG. 2, the vent plug 30 includes a housing 40 that has a cylindrical shape and has a vent hole 32 on the inner diameter side, and a stem 50 that is inserted on the inner diameter side of the housing 40 and opens and closes the vent hole 32. In FIG. 2, the upper side is the inside of the mold, and the lower side is the outside of the mold. Since the outer diameter of the housing 40 is slightly larger than the inner diameter of the plug mounting hole 20, the vent plug 30 can be fitted into the plug mounting hole 20.

  The vent hole 32 of the housing 40 communicates the inside of the mold and the outside of the mold. The mold inner end surface 42 of the housing 40 is on the same plane as the molding surface 18 of the molding member on which the housing 40 is provided, and is a part of the molding surface 18. However, there may be a step that does not cause a problem in appearance, for example, a step of 0.1 mm or less, between the mold inner end surface 42 of the housing 40 and the molding surface 18 around it. Of the inner diameter surface of the housing 40, that is, the surface that forms the vent hole 32, the surface that continues from the mold inner end surface 42 of the housing 40 in the depth direction of the housing 40 (that is, outward from the mold) is the vent hole of the vent plug 30. This is a contact surface 44 that contacts the stem 50 when 32 is closed. The contact surface 44 is tapered so that the diameter decreases toward the outside of the mold. Therefore, the contact surface 44 is inclined with respect to the vent plug axial direction. Of the inner diameter surface of the housing 40, the surface continuing from the contact surface 44 to the outside of the mold has a constant diameter. A protrusion 46 protruding toward the inner diameter side of the housing 40 is provided at an end of the housing 40 outside the mold or in the vicinity thereof. At the position of the protrusion 46, the inner diameter of the housing 40 is small.

  The stem 50 includes a head 54 having a mold inner end face 52 that is a part of the molding surface 18, a first body 56 continuous from the head 54 to the outside of the mold, and a mold from the first body 56. And a second body 57 that continues outward. These outer diameters are larger in the order of the head 54, the first body 56, and the second body 57. The outer diameter surface 53 of the head 54 is a surface that contacts the contact surface 44 of the housing 40 when the vent hole 32 is closed. The outer diameter surface 53 of the head 54 is a tapered surface so that the diameter decreases toward the outside of the mold. Therefore, the outer diameter surface 53 is inclined with respect to the vent plug axial direction. The inclination angle of the outer diameter surface 53 coincides with the inclination angle of the contact surface 44. A protrusion 58 that protrudes toward the inner diameter surface of the plug mounting hole 20 is provided at an end of the second body 57 outside the mold or in the vicinity thereof. The outer diameter of the stem 50 at the position of the protrusion 58 is larger than the inner diameter of the housing 40 at the position of the protrusion 46. Further, the outer diameters of the first body portion 56 and the second body portion 57 are smaller than the inner diameter of the housing 40, and there is a gap between the outer diameter surface of the first body portion 56 and the second body portion 57 and the inner diameter surface of the housing 40. Air can pass through this gap.

  A spring 34 (another elastic member may be provided in place of the spring 34) is provided as a part of the vent plug 30 between the protrusion 46 of the housing 40 and the first body portion 56 of the stem 50. Yes. The spring 34 urges the stem 50 toward the inside of the mold. Therefore, when no force is applied to the stem 50 to push the mold 50 outward, the mold inner end face 52 of the head 54 of the stem 50 protrudes more inside the mold than the mold inner end face 42 of the housing 40. A gap is formed between the contact surface 44 of the housing 40 and the outer diameter surface 53 of the head portion 54 of the stem 50 (this gap is referred to as “a gap between the contact surface 44 and the stem 50”), and the vent hole 32 is opened. It is in a state. The “open state” refers to a state in which no force is applied to the stem 50 to push the stem 50 to the outside of the mold. In the open state of the vent hole 32, the air inside the mold can pass through the gap between the contact surface 44 and the stem 50, escape from the vent plug 30 to the outside of the mold, and escape to the outside of the mold. In the open state of the vent hole 32, the open end with respect to the molding surface 18 of the space between the housing 40 and the stem 50, which is the air inlet to the vent plug 30, is ring-shaped. The length M of the gap between the contact surface 44 and the stem 50 in the opened state of the vent hole 32 (that is, the distance in the direction perpendicular to the contact surface 44) is preferably 0.04 mm ≦ M ≦ 0.30 mm. More preferably, 20 mm ≦ M ≦ 0.30 mm (see FIG. 5).

  When the stem 50 is pushed outside the mold against the biasing force of the spring 34, the contact surface 44 of the housing 40 and the outer diameter surface 53 of the head 54 of the stem 50 come into contact with each other, and the contact surface 44 and the stem The gap with 50 is closed. Then, the air inside the mold cannot escape to the outside of the mold. Also, fluid rubber is less likely to enter the gap between the contact surface 44 and the stem 50.

  The protrusion 58 of the stem 50 is located outside the mold from the protrusion 46 of the housing 40. As described above, the outer diameter of the stem 50 at the position of the protrusion 58 is larger than the inner diameter of the housing 40 at the position of the protrusion 46. Therefore, when the projection 58 hits the projection 46 from the outside of the mold, the stem 50 cannot move further inside the mold. Therefore, the stem 50 does not fall out from the housing 40 to the inside of the mold.

  As shown in FIGS. 3 and 4, one or more rubbers extending in the depth direction of the housing 40 from the mold inner end surface 42 which is a part of the molding surface 18 along the contact surface 44 of the housing 40. A guide groove 47 is provided. The number of guide grooves 47 is not limited, but is preferably a plurality of guide grooves 47 and more preferably four or more. Further, it is desirable that the plurality of guide grooves 47 are arranged at equal intervals in the circumferential direction of the contact surface 44. An end portion of the guide groove 47 inside the mold reaches the molding surface 18 (mold inner end surface 42). Further, the outer end of the guide groove 47 is terminated within the range of the contact surface 44. The shape of the guide groove 47 on the cross section in the direction parallel to the molding surface 18 is not limited, but is rectangular in FIG. When the vent hole 32 is in a closed state, only the end portion inside the mold of the guide groove 47 opens in the molding surface 18.

  As shown in FIGS. 3 to 5, a circumferential groove 48 is provided along the contact surface 44 of the housing 40 so as to cross the guide groove 47 and extend circumferentially. More specifically, the circumferential groove 48 intersects with the end of the guide groove 47 outside the mold and makes one round in the circumferential direction of the contact surface 44. The depth (length in the vent plug axial direction) P of the housing 40 from the mold inner end face 42 of the place where the circumferential concave groove 48 is provided is determined from the end of the contact face 44 inside the mold. It is desirable that the depth is 20% or more and 50% or less of the depth Q to the outer end.

  The shape of the circumferential concave groove 48 on the cross section in the vent plug axial direction is not limited, but the width is narrower at the bottom 48b than the opening end 48a (that is, the length in the direction parallel to the contact surface 44 is short). It is desirable to be. 4 and 5, the shape of the circumferential concave groove 48 on the cross section in the vent plug axial direction is a semicircular shape.

  The depth L in the direction perpendicular to the contact surface 44 of the circumferential groove 48 (that is, the depth in the direction perpendicular to the contact surface 44 from the opening end 48a to the bottom 48b of the circumferential groove 48) is 0. It is desirable that 10 mm ≦ L ≦ 0.03 mm. However, the depth L in the direction perpendicular to the contact surface 44 of the circumferential concave groove 48 is preferably shallower than the length M of the gap between the contact surface 44 and the stem 50 in the open state of the vent hole 32 (see FIG. 5). ).

  Further, the width N (that is, the length in the direction parallel to the contact surface 44) of the opening end 48a of the circumferential concave groove 48 is 10% or more of the length O of the contact surface 44 in the section in the vent plug axial direction. % Or less is desirable (see FIG. 5).

  Although the material of the housing 40 and the stem 50 is not limited, for example, a steel material such as a general structural rolled steel material (for example, SS400), copper, or the like is used. The material of the housing 40 and the material of the stem 50 may be the same or different.

  When vulcanization molding of a pneumatic tire is performed with the tire vulcanization mold 10 provided with the vent plug 30, an unvulcanized tire is set inside the tire vulcanization mold 10. Then, a bladder (not shown) arranged inside the set unvulcanized tire expands, and the surface of the unvulcanized tire is pressed against the molding surface 18. Further, the molding member such as the sector 12 is held at the vulcanization molding temperature. Then, the air remaining inside the tire vulcanization mold 10 escapes to the outside of the tire vulcanization mold 10 through the open air vent 32. At the same time, the fluid rubber of the unvulcanized tire approaches the vent plug 30.

  When the rubber reaches the vent plug 30 from the vent plug axial direction, the rubber first presses the 52 of the stem 50, and the vent hole 32 is closed. Next, the rubber enters the guide groove 47 and then enters the circumferential groove 48 where the penetration stops. The intruded rubber is molded in the guide groove 47 and the circumferential groove 48. Therefore, the rubber molded between the housing 40 and the stem 50 is composed of rubber molded in the guide groove 47 and rubber molded in the circumferential groove 48.

  Further, when the rubber reaches the vent plug 30 from the direction along the molding surface 18, the rubber enters between the housing 40 and the stem 50 before pressing the mold inner end surface 52 of the stem 50. Thereafter, the rubber pushes the mold inner end face 52 of the stem 50. In many cases, the vent hole 32 is not completely closed. As a result, the rubber enters the guide groove 47, the circumferential groove 48, and the gap between the contact surface 44 and the stem 50 (mainly, the portion inside the mold from the circumferential groove 48). . Therefore, the rubber molded between the housing 40 and the stem 50 is composed of the rubber molded in the guide groove 47, the rubber molded in the circumferential groove 48, the contact surface 44 and the stem 50. It consists of rubber molded in the gap.

  In any case, when the pneumatic tire is taken out from the tire vulcanization mold 10 after vulcanization molding, the rubber molded between the housing 40 and the stem 50 is pulled to the tire surface molded on the molding surface. It is done. At that time, the rubber molded in the guide groove 47 serves as a thick and hard torn reinforcing part, and the entire rubber molded between the housing 40 and the stem 50 is pulled out without tearing.

  As described above, in the tire vulcanization mold 10 according to this embodiment, even when rubber enters between the housing 40 and the stem 50, the pneumatic tire is taken out from the tire vulcanization mold 10. The rubber molded in the guide groove 47 serves as a reinforcing portion, and the entire molded rubber between the housing 40 and the stem 50 is pulled out and removed without tearing. In addition, the effect will be large if there are provided a plurality of guiding concave grooves 47, particularly four or more.

  Further, since the opening end of the space between the housing 40 and the stem 50 with respect to the molding surface 18 is ring-shaped, the rubber that has entered between the housing 40 and the stem 50 is easily molded into a ring shape. When rubber that has entered between the housing 40 and the stem 50 is molded in a ring shape, the tire surface molded on the molding surface and the rubber molded between the housing 40 and the stem 50 are connected in a ring shape. Therefore, the rubber molded between the housing 40 and the stem 50 is difficult to tear. Therefore, when the pneumatic tire is taken out from the tire vulcanization molding die 10, the entire rubber molded between the housing 40 and the stem 50 is removed without tearing.

  Further, since the circumferential concave groove 48 that intersects with the guiding concave groove 47 and makes one round in the circumferential direction of the contact surface 44 is provided, the rubber that has entered the guiding concave groove 47 passes through the circumferential concave groove 48 in the circumferential direction. The rubber that can move and intrudes between the housing 40 and the stem 50 is particularly easily formed into a ring shape. Therefore, the effect becomes remarkable.

  When the depth L in the direction perpendicular to the contact surface 44 of the circumferential groove 48 is shallower than the length M of the gap between the contact surface 44 and the stem 50 in the opened state of the vent hole 32, the contact surface 44 and the stem The thickness of the rubber that has entered into the gap 50 is sufficiently secured, and the thickness of the rubber that has entered the circumferential concave groove 48 and is molded there is not too thick. Therefore, when the rubber molded between the housing 40 and the stem 50 is pulled to the inside of the mold, it is difficult to tear at the rubber portion molded in the gap between the contact surface 44 and the stem 50, and the circumferential concave The rubber molded in the groove 48 is easily removed from the circumferential concave groove 48. In particular, if rubber has entered between the housing 40 and the stem 50 with the vent hole 32 open, the gap between the contact surface 44 and the stem 50 enters and the thickness of the molded rubber is sufficiently secured. Rubber is difficult to tear.

  Further, if the circumferential groove 48 is narrower at the bottom 48b than the opening end 48a on the cross section in the vent plug axial direction, the rubber molded in the circumferential groove 48 is pulled inside the mold. It is easy to come out of the circumferential groove 48 without being caught.

  Further, the depth from the mold inner end surface 42 of the housing 40 at the location where the circumferential groove 48 is provided is the depth from the inner end of the contact surface 44 to the outer end of the mold. 20% or more, it is difficult for the rubber that has entered between the housing 40 and the stem 50 to penetrate from the circumferential groove 48 to the outside of the mold. Further, the depth from the mold inner end surface 42 of the housing 40 at the location where the circumferential groove 48 is provided is the depth from the inner end of the contact surface 44 to the outer end of the mold. If it is 50% or less, the circumferential groove 48 and the molding surface 18 are not too far, so that when the rubber molded between the housing 40 and the stem 50 is pulled from the inside of the mold, the circumferential shape The rubber molded in the concave groove 48 is easily removed from the circumferential concave groove 48.

  Further, if the width N of the opening end 48a of the circumferential groove 48 is 10% or more of the length O of the contact surface 44 on the cross section in the vent plug axial direction, a large amount of rubber accumulates in the circumferential groove 48. Therefore, the effect of the circumferential groove 48 is great. Further, if the width N of the opening end 48a of the circumferential groove 48 is 50% or less of the length O of the contact surface 44 on the cross section in the vent plug axial direction, the circumferential groove is formed in the molded pneumatic tire. The rubber molded in 48 is inconspicuous and does not significantly affect the appearance quality.

  Various changes, substitutions, omissions, and the like can be made to the above embodiments without departing from the scope of the invention. A modified guide groove 147 is shown in FIG. 6, and a modified circumferential groove 148 is shown in FIG. The shape of the guide groove 147 on the cross section in the direction parallel to the mold inner end face 42 of the housing 40 may be a triangle having the groove bottom as one apex as shown in FIG. It may be semicircular as shown in 6 (b). Further, although not shown, the circumferential concave groove 48 may not be provided on the contact surface 44. Moreover, various examples of modification are given as the shape of the circumferential concave groove 148 on the cross section in the vent plug axial direction. As a modification of the shape having a narrower width at the bottom 48b than the open end 48a, a triangle whose groove bottom shown in FIG. 7 (a) is one of the vertices (the vertex may be rounded as shown in FIG. 7), The trapezoid etc. from which the bottom part 48b shown in FIG.7 (b) becomes a shorter base are mentioned. Another modification is a rectangle shown in FIG.

DESCRIPTION OF SYMBOLS 10 ... Mold for tire vulcanization molding, 12 ... Sector, 14 ... Side plate, 16 ... Bead ring, 18 ... Molding surface, 20 ... Plug mounting hole, 30 ... Vent plug, 32 ... Vent hole, 34 ... Spring, 40 ... Housing, 42 ... Mold inner end surface, 44 ... Contact surface, 46 ... Protrusion, 47 ... Guide groove, 48 ... Ground groove, 48a ... Open end, 48b ... Bottom, 50 ... Stem, 52 ... Mold inside End surface, 53 ... outer diameter surface, 54 ... head, 56 ... first torso, 57 ... second torso, 58 ... projection, 147 ... guide groove, 148 ... circumferential groove

Claims (4)

A molding member having a molding surface for molding the tire surface, a plug mounting hole provided in the molding member to communicate the inside of the mold and the outside of the mold, and a vent plug fitted in the plug mounting hole, The vent plug includes a cylindrical housing having a vent hole on the inner diameter side from the inside of the mold to the outside of the mold, and a stem that is inserted into the inner diameter side of the housing and opens and closes the vent hole. In the tire vulcanization molding die in which the surface continuous from the molding surface among the surfaces forming the ventilation holes is a contact surface that comes into contact with the stem when the ventilation holes are closed,
A tire vulcanization molding die provided with a guide groove for rubber extending from the molding surface in the depth direction of the housing along the contact surface.   The tire vulcanization mold according to claim 1, wherein a circumferential concave groove is provided along the contact surface so as to intersect with the induction concave groove and extend circumferentially.   The depth in the direction perpendicular to the contact surface of the circumferential groove is shallower than the distance in the direction perpendicular to the contact surface between the contact surface and the stem in the opened state of the vent plug. Tire vulcanization mold.   4. The tire vulcanization mold according to claim 2, wherein the circumferential groove has a shape that is narrower at a bottom portion than an opening end on an axial section of the vent plug. 5.

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