JP2017109441A - Mold for vulcanizing and molding tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for vulcanizing and molding a tire less likely to enlarge a prepared hole however often a change piece is replaced, and less likely to generate an unnecessary rubber projection on a tire surface.SOLUTION: In a mold for vulcanizing and molding a tire including a molding member 14 provided with a prepared hole 20 on a surface for molding a tire surface, and a change piece 30 to be fitted into the prepared hole 20, a part 32 including a surface 31 for molding the tire surface of the change piece 30 has a higher thermal expansion coefficient than the molding member 14, and has a clearance to a side wall where the prepared hole 20 is formed, and the clearance is closed at a vulcanization molding temperature.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a tire vulcanization mold.

  On the surface of the pneumatic tire (tire surface), for example, characters such as a tire size, a road index, a manufacturer name, a manufacturing date, a manufacturing number, a symbol, and the like are displayed. These characters and symbols are formed by transfer during vulcanization molding. In other words, the surface (inner surface) on which the tire surface of the tire vulcanization mold is molded has characters and symbols formed as recesses, and rubber flows into the recesses during vulcanization molding. Characters and symbols are formed on the screen.

  By the way, even if it is a pneumatic tire with the same external shape, the character, symbol, etc. which should be displayed on the surface may differ. Therefore, in the tire vulcanization mold, only parts such as letters and symbols can be replaced. Specifically, a pilot hole is formed in the inner surface of the tire vulcanization molding die, and a replacement piece is fitted in the pilot hole. Characters, symbols, and the like are formed as recesses on the surface of the replacement piece. And when a character, a symbol, etc. are changed, only a replacement piece is replaced (for example, refer to patent documents 1-3).

  Conventional replacement pieces are made of the same material as the surrounding parts of the tire vulcanization mold. The replacement piece is made to a certain size so that it can be fitted into the pilot hole of the tire vulcanization mold, and is fitted by being struck firmly into the pilot hole.

Japanese Patent Laid-Open No. 11-77694 JP 2000-202832 A Japanese Patent Laid-Open No. 2001-179751

  By the way, as a basic matter required for a tire vulcanization mold, it is possible to prevent unnecessary rubber protrusions from occurring on the tire surface as much as possible.

  However, if the replacement piece is strongly struck into the lower hole, the replacement hole is enlarged and a gap is formed between the replacement piece and the replacement piece while the replacement piece is being replaced many times. In addition, a new replacement piece may be additionally manufactured in order to display a different indication on the tire surface. In the process of manufacturing, it is necessary to finish the shape by hitting the new replacement piece into the pilot hole. At this time, if the replacement piece is strongly struck into the prepared hole, the prepared hole expands and a gap is generated between the existing replacement piece and the prepared hole. Then, if the vulcanization molding of the pneumatic tire is performed with this gap remaining, rubber flows into this gap, and unnecessary rubber protrusions are formed around the letters and symbols of the pneumatic tire. Will occur. In order to prevent the occurrence of this protrusion, a measure for filling the gap is required.

  The present invention has been made in view of the above circumstances, and the tire vulcanization molding in which the pilot hole is difficult to expand and unnecessary rubber protrusions are not easily generated on the tire surface even if the replacement piece is replaced many times. An object is to provide a metal mold.

  In the tire vulcanization mold according to the embodiment, a tire vulcanization mold including a molding member provided with a pilot hole on a surface for molding the tire surface and a replacement piece fitted into the pilot hole, The portion including the surface for molding the tire surface of the replacement piece has a larger coefficient of thermal expansion than the molding member, has a gap with respect to the side wall forming the pilot hole, and the gap is closed at the vulcanization molding temperature. It is characterized by.

  In the tire vulcanization mold according to the embodiment, since the portion including the surface for molding the tire surface of the replacement piece has a gap with respect to the side wall forming the prepared hole, the replacement piece is not strongly struck into the prepared hole. No matter how many times the replacement piece is replaced, the pilot hole is difficult to expand. In addition, since the portion including the surface for molding the tire surface of the replacement piece has a larger coefficient of thermal expansion than the molded member and the gap is closed at the vulcanization molding temperature, unnecessary rubber protrusions are unlikely to occur on the tire surface.

Sectional drawing of the axial direction of the metal mold | die 10 for tire vulcanization molding. The figure which looked at the replacement piece 30 fitted by the side plate 14 from the metal mold | die inner surface side. Sectional drawing in the surface which passes along the pilot hole 20 of the side plate 14 before the replacement | exchange piece 30 fitting. Sectional drawing in AA of FIG. Sectional drawing in the surface which passes along the replacement piece 30 of the side plate 14. FIG. Sectional drawing in BB of FIG. Sectional drawing in the surface which passes along the replacement piece 130 of the side plate of the comparative examples 1 and 2. FIG.

  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 beads. And a ring 16. The plurality of sectors 12 mainly forms a tread portion of a pneumatic tire, the pair of side plates 14 forms a side portion (tire side portion) of the pneumatic tire, and the pair of bead rings 16 forms a bead portion of the pneumatic tire. To do. 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. The sector 12, the side plate 14, and the bead ring 16 are heated to a vulcanization molding temperature (for example, any one of 130 to 200 ° C.) by an electric heater or high-temperature steam (not shown) at the time of vulcanization molding.

  As shown in FIG. 1 and FIG. 2, the side plate 14 that is a molded member is replaced with characters such as tire size, road index, manufacturer name, date of manufacture, serial number, etc. A piece 30 is provided. Some replacement pieces 30 have no plain characters or symbols. Hereinafter, the replacement piece 30 and the surrounding structure will be described.

  As shown in FIGS. 3 and 4, a pilot hole 20 is provided at the place where the replacement piece 30 is provided on the side plate 14 by spot facing or the like from the inner surface side of the mold. The pilot hole 20 is a hole into which the replacement piece 30 is fitted. The pilot hole 20 is formed by a bottom surface 21a and a side wall 21b extending from the end of the bottom surface 21a to the inner surface of the mold. Further, the bolt hole 22 penetrates from the bottom surface 21a of the prepared hole 20 to the outside of the mold.

  5 and 6 show a state in which the replacement piece 30 is fitted in the prepared hole 20. As shown in FIG. 4, a bolt hole 35 is provided from the outside of the mold as a fixing portion for the side plate 14 in a portion outside the mold of the replacement piece 30 (a lower layer portion 34 described later). With the replacement piece 30 fitted in the pilot hole 20 of the side plate 14, a bolt 23 is inserted into the bolt hole 35 and the bolt hole 22 of the side plate 14. It is fixed to. At this time, the bottom surface 37 of the replacement piece 30 and the bottom surface 21a of the pilot hole 20 are in contact with each other. However, the fixing method with respect to the pilot hole 20 of the replacement piece 30 is not limited to this.

  As shown in FIGS. 3 to 6, the replacement piece 30 includes an upper layer portion 32 including a surface for molding the tire surface (referred to as a tire molding surface 31), and a lower layer portion 34 provided outside the mold of the upper layer portion 32. With. Although the fixing method of the upper layer part 32 and the lower layer part 34 is not limited, In this embodiment, it fixes with the screw | thread 36. FIG. Specifically, two or more screw holes 36a pass through the lower layer portion 34 from the mold outer surface side toward the inner surface side. Further, screw holes 36b extending from the mold outer surface side and terminating in the upper layer portion 32 are provided at positions corresponding to the screw holes 36a of the upper layer portion 32, respectively. A screw 36 is inserted into the screw hole 36a and the screw hole 36b, and the upper layer portion 32 and the lower layer portion 34 are fixed. The replacement piece 30 in which the upper layer portion 32 and the lower layer portion 34 are integrated is tapered. That is, the piece 30 has a trapezoidal shape on a cross section in a direction perpendicular to the tire molding surface 31, and the area of the tire molding surface 31 is a surface facing the bottom surface 21 a of the pilot hole 20 (the bottom surface 37 of the replacement piece 30 and To be larger than the area.

  The place where the above-mentioned letters and symbols are formed is the tire molding surface 31 of the upper layer portion 32. The letters and symbols are engraved by mechanical engraving or hand-cut engraving. The upper layer portion 32 is tapered. That is, the upper layer portion 32 has a trapezoidal shape on a cross section perpendicular to the tire molding surface 31, and the area of the tire molding surface 31 is larger than the area of the contact surface 33 (see FIG. 4) with the lower layer portion 34. ing. The lower layer part 34 is also tapered so that the entire replacement piece 30 is tapered.

  At room temperature, that is, 5 to 35 ° C., the replacement piece 30 has a gap with respect to the bottom surface 21 a and the side wall 21 b forming the prepared hole 20. Specifically, at normal temperature, the area of the tire molding surface 31 is slightly smaller than the area of the opening end 24 of the pilot hole 20 on the inner surface of the mold. Therefore, as shown in FIG. 2, a gap is generated between the edge 38 of the tire molding surface 31 of the replacement piece 30 and the edge 25 of the upper end of the side wall 21 b of the pilot hole 20. This gap is closed when the upper layer portion 32 expands at the above vulcanization molding temperature. The gap length L (see FIG. 2) is, for example, 0.01 mm ≦ L ≦ 0.07 mm both in the tire circumferential direction and in the tire radial direction. Further, depending on the material and thickness of the replacement piece 30 (the length in the direction perpendicular to the tire molding surface 31), the thickness of the replacement piece 30 may easily change due to thermal expansion. In that case, the tire molding surface 31 of the replacement piece 30 is slightly more than the surrounding tire molding surface (for example, 0.01) with the bottom surface 37 of the replacement piece 30 and the bottom surface 21a of the pilot hole 20 in contact with each other at room temperature. It may be recessed.

  The upper layer portion 32 has a higher coefficient of thermal expansion than the side plate 14 and the lower layer portion 34. Although the material of the upper layer part 32 is not limited, For example, it is aluminum or aluminum alloy. Moreover, although the material of the lower layer part 34 is not limited, For example, they are steels, such as a general structural rolled steel material. The material of the side plate 14 and the material of the lower layer part 34 may be the same or different.

  When vulcanization molding of a pneumatic tire is performed with the tire vulcanization molding die 10 having the above structure, an unvulcanized tire is set inside the tire vulcanization molding die 10. Then, a bladder (not shown) arranged inside the set unvulcanized tire expands, and the surface of the unvulcanized tire is pressed against the inner surface of the mold (tire molding surface). In this state, the side plate 14 of the tire vulcanization molding die 10 is held at the above vulcanization molding temperature, and the unvulcanized tire is vulcanized. As a result, characters, symbols, and the like formed on the replacement piece 30 are transferred to the tire side portion.

  In this vulcanization molding, when the side plate 14 and the replacement piece 30 rise to the vulcanization molding temperature, the upper layer portion 32 of the replacement piece 30 has a higher coefficient of thermal expansion than the side plate 14 as described above. 32 is thermally expanded, and the gap between the edge 38 of the tire molding surface 31 of the replacement piece 30 and the edge 25 of the pilot hole 20 is closed. Therefore, the rubber of the unvulcanized tire does not flow between the edge portion 38 of the tire molding surface 31 of the replacement piece 30 and the edge portion 25 of the pilot hole 20. Here, since the replacement piece 30 is tapered as described above, when the upper layer portion 32 of the replacement piece 30 is thermally expanded, only the vicinity of the edge 38 of the tire molding surface 31 of the replacement piece 30 is a pilot hole. 20 is in contact with the vicinity of the edge 25 of the side wall 21b. That is, the replacement piece 30 and the side wall 21b of the pilot hole 20 are in line contact or in a close contact state.

  When changing the character or symbol of the tire side portion, or when changing the portion where the character or symbol or the like of the tire side portion has been displayed to a plain color, the operator can use the upper layer 32 of the replacement piece 30 of the side plate 14. Replace only. Specifically, first, the operator removes the bolt 23 and takes out the replacement piece 30 from the prepared hole 20 of the side plate 14. Next, the operator removes the screw 36 and removes the upper layer portion 32 before the change from the lower layer portion 34, and fixes the new upper layer portion 32 to the lower layer portion 34 before the change with the screw 36. Then, the operator puts the replacement piece 30 to which the new upper layer portion 32 is fixed into the prepared hole 20 of the side plate 14 and fixes it with the bolts 23. Here, since there is a gap between the tire molding surface 31 of the replacement piece 30 and the edge 25 of the pilot hole 20, it is not necessary for the operator to strike the replacement piece 30 strongly.

  The tire vulcanization molding die 10 of the present embodiment has the following effects. First, since the replacement piece 30 has a gap with respect to the side wall 21b that forms the prepared hole 20 of the side plate 14, it is not necessary for the operator to strike the replacement piece 30 strongly when putting it into the prepared hole 20. Therefore, the pilot hole 20 is difficult to expand regardless of how many times the replacement piece 30 is replaced. Moreover, since the thermal expansion coefficient of the upper layer portion 32 of the replacement piece 30 is larger than the thermal expansion coefficient of the side plate 14, the upper layer portion 32 expands in the vulcanization molding process, and the side wall that forms the replacement piece 30 and the lower hole 20. The gap between 21b is closed. Therefore, rubber does not flow between the replacement piece 30 and the side wall 21b forming the pilot hole 20, and unnecessary rubber protrusions are unlikely to occur on the tire surface after vulcanization molding. In addition, there is no possibility that the side plate 14 is deformed when the operator strikes the replacement piece 30 into the prepared hole 20 strongly.

  Further, when a new replacement piece 30 is additionally manufactured in addition to the existing replacement piece 30, it is not necessary for the operator to strike the new replacement piece 30 in the middle of manufacture into the lower hole 20, so that the lower hole 20 is formed. Difficult to expand. Therefore, it is difficult for a gap to be generated between the existing replacement piece 30 and the pilot hole 20.

  In addition, the pilot hole 20 is enlarged and it becomes necessary to produce a large replacement piece 30 that fits the pilot hole 20, or the replacement piece 30 is strongly struck into the lower hole 20 to be deformed to form a new replacement piece 30. It is difficult to make a new one.

  Further, since the replacement piece 30 includes the upper layer portion 32 and the lower layer portion 34, the characters and symbols of the tire side portion can be changed by exchanging only the upper layer portion 32. Therefore, it is not necessary to prepare as many replacement pieces 30 as the number of types such as characters and symbols, and only the upper layer portion 32 needs to be prepared, so that the cost can be reduced. Moreover, since the lower layer part 34 has a small coefficient of thermal expansion, there is no possibility of being strongly pressed against the side wall 21b of the prepared hole 20 even at the vulcanization molding temperature. Therefore, the lower layer part 34 is hard to deform | transform and can be used any number of times.

  Further, since the thermal expansion coefficient of the lower layer part 34 is smaller than the thermal expansion coefficient of the upper layer part 32, the lower layer part 34 is less deformed due to temperature change than the upper layer part 32. Therefore, the lower layer 34 is fixed to the side plate 14 so that the entire replacement piece 30 is not displaced. In particular, if the lower layer portion 34 and the side plate 14 are made of the same material, the deformation amount accompanying the temperature change of the lower layer portion 34 and the side plate 14 is the same. Is done.

  Further, if the lower layer 34 is made of steel, the crest (screw thread) inside the bolt hole 35 of the lower layer 34 is not easily crushed, so that the bolt 23 can strongly pull the lower layer 34 to the side plate 14 side. The replacement piece 30 and the side plate 14 are firmly fixed. Here, when the lower layer portion 34 is made of steel, the replacement piece 30 is not easily displaced if the side plate 14 is also made of steel. In the case where the side plate 14 is made of steel, if the upper layer portion 32 is made of aluminum or an aluminum alloy, the effect based on the difference in the thermal expansion coefficient is remarkably exhibited.

  Moreover, since the upper layer part 32 and the lower layer part 34 are being fixed with the screw | thread 36, replacement | exchange of the upper layer part 32 is easy.

  If the length L of the gap between the upper layer portion 32 of the replacement piece 30 and the side wall 21b forming the lower hole 20 is 0.01 mm ≦ L ≦ 0.07 mm, the operator places the replacement piece 30 into the lower hole 20. When inserting, it is not necessary to strike the replacement piece 30 strongly, and when the vulcanization molding temperature is reached, the gap is completely closed.

  Further, since the replacement piece 30 is tapered, when the operator puts the replacement piece 30 into the lower hole 20, the replacement piece 30 and the side wall 21 b of the lower hole 20 are unlikely to come into surface contact. Easy to put in the pilot hole 20.

  Various changes, substitutions, omissions, and the like can be made to the above embodiments without departing from the scope of the invention. For example, the replacement piece does not necessarily need to be divided into the upper layer portion and the lower layer portion, and may be one member made of one material having a larger coefficient of thermal expansion than the side plate 14 as a whole. Further, the characters, symbols, and the like formed on the replacement piece 30 may be formed not only as concave portions but also as convex portions.

  The tire vulcanization molds of Comparative Examples and Examples shown in Table 1 were evaluated. In the tire vulcanization molds of Comparative Examples 1 to 3 and Example 1, a pilot hole was provided in the side plate made of SS400, and a replacement piece was fitted into the pilot hole. FIG. 7 shows a state where the replacement piece 130 of Comparative Example 1 and Comparative Example 2 is fitted in the prepared hole 20 of the side plate 14. The replacement piece 130 of Comparative Example 1 is a conventional replacement piece that is not divided into an upper layer portion and a lower layer portion, and is entirely made of SS400, and there is no gap between the replacement piece 130 and the side wall of the lower hole 20 at room temperature. Is. The replacement piece 130 of Comparative Example 2 is not divided into an upper layer portion and a lower layer portion and is entirely made of aluminum, and there is no gap between the replacement piece 130 and the side wall of the lower hole 20 at room temperature. In the replacement piece of Comparative Example 3, the upper layer portion is made of aluminum and the lower layer portion is made of SS400, and there is no gap between the replacement piece and the side wall of the pilot hole at room temperature. In the replacement piece of Example 1, the upper layer is made of aluminum and the lower layer is made of SS400, and there is a gap between the replacement piece and the side wall of the pilot hole at room temperature.

  Evaluation item 1 is the amount of deformation of the pilot hole when the operator inserts a new replacement piece into a new side plate, uses the tire vulcanization mold, and then takes out the replacement piece. ○ means that there is almost no deformation, Δ means that the amount of deformation is small, and × means that the amount of deformation is large.

  The evaluation item 2 is good exchange workability of the replacement piece evaluated by the worker. ○ means that the work is easy, Δ means that the work is slightly difficult, and x means that the work is extremely difficult.

  Evaluation item 3 is the necessity of reworking of the replacement piece when the worker uses it once and re-uses the replacement piece taken out from the pilot hole of the side plate, and the degree of reworking when reworking is necessary It is. ○ means that reworking is unnecessary or slight reworking is necessary, △ means that a certain amount of reworking is necessary, and × means that a large amount of reworking is necessary or a replacement piece needs to be recreated. Yes.

  The evaluation results are shown in Table 1. Since the replacement piece 130 of Comparative Example 1 is made of SS400 having high hardness and there is no gap between the replacement piece 130 and the side wall of the pilot hole 20, an operator needs to fit the replacement piece 130 into the pilot hole 20. It was necessary to strike the replacement piece 130 strongly. For this reason, the amount of deformation of the pilot hole 20 is large, and the replacement piece 130 is also deformed to require large rework.

  The replacement piece 130 of Comparative Example 2 is made of aluminum whose hardness is lower than that of SS400, but there is no gap between the replacement piece 130 and the pilot hole 20, so that the replacement piece 130 is fitted in the pilot hole 20. The operator had to strike the replacement piece 130 to some extent. Therefore, the amount of deformation of the pilot hole 20 is small, and the replacement piece 130 is slightly deformed, so that some rework is required. Further, since the replacement piece 130 of Comparative Example 2 is entirely made of aluminum, when an operator strongly screws a bolt into the replacement piece 130 in order to fix the replacement piece 130 in the lower hole 20, the screw of the bolt hole of the replacement piece 130. There was a problem that the mountain collapsed. Therefore, in order for the operator to fix the replacement piece 130 to the pilot hole 20, it is necessary to screw a bolt into the replacement piece 130 and strike the replacement piece 130 from the inner surface of the mold toward the lower hole 20. It was a little difficult.

  Since the upper part of the replacement piece of Comparative Example 3 is made of aluminum and there is no gap between the replacement piece and the side wall of the lower hole, the evaluation result is equivalent to that of the replacement piece of Comparative Example 2.

  In the replacement piece of Example 1, there was a gap between the replacement piece and the side wall of the pilot hole, so that the operator did not have to strike the replacement piece strongly to fit the replacement piece into the pilot hole. Therefore, there was almost no deformation of the pilot hole, and the replacement piece could be reused with a slight rework. Also, the replacement work was easy.

DESCRIPTION OF SYMBOLS 10 ... Mold for tire vulcanization molding, 12 ... Sector, 14 ... Side plate, 16 ... Bead ring, 20 ... Pilot hole, 21a ... Bottom face of pilot hole 20, 21b ... Side wall, 22 ... Bolt hole, 23 ... Bolt, 24 ... Open end, 25 ... Edge of pilot hole 20, 30 ... Replacement piece, 31 ... Tire molding surface, 32 ... Upper layer portion, 33 ... Contact surface, 34 ... Lower layer portion, 35 ... Bolt hole, 36 ... Screw, 36a ... Screw hole, 36b ... Screw hole, 37 ... Bottom surface of replacement piece 30, 38 ... Edge of tire molding surface 31, 130 ... Replacement piece

Claims (5)

In a mold for tire vulcanization molding comprising a molding member provided with a pilot hole on the surface for molding the tire surface, and a replacement piece fitted into the pilot hole,
The portion including the surface for molding the tire surface of the replacement piece has a larger coefficient of thermal expansion than the molding member, has a gap with respect to the side wall forming the pilot hole, and the gap closes at the vulcanization molding temperature. Mold for tire vulcanization molding.   The replacement piece includes an upper layer portion including a surface for molding the tire surface, and a lower layer portion having a fixing portion for the molding member, and the thermal expansion coefficient of the lower layer portion is smaller than the thermal expansion coefficient of the upper layer portion. The tire vulcanization mold according to claim 1.   The tire vulcanization mold according to claim 2, wherein the upper layer part is made of aluminum or an aluminum alloy, and the lower layer part and the molding member are made of steel.   The mold for tire vulcanization molding according to claim 2 or 3, wherein the upper layer portion and the lower layer portion are fixed with screws. The length L of the gap between the portion including the surface for molding the tire surface of the replacement piece and the side wall forming the pilot hole is 0.01 mm ≦ L ≦ 0.07 mm.
The mold for tire vulcanization molding according to any one of claims 1 to 4.

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