JP7175753B2 - Manufacturing method of tire vulcanization mold - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a tire vulcanization mold .

A tire vulcanizing mold includes a sector mold having a plurality of sectors for molding a tread portion of a pneumatic tire, and a pair of side molds for molding a side portion of the pneumatic tire. Vent holes are formed at predetermined positions in these molds for discharging the air in the mold (cavity). Patent Document 1 discloses a cylindrical vent piece attached to this vent hole.

Japanese Utility Model Laid-Open No. 6-42122

The inner surface side of the mold constitutes a molding surface (profile surface) having steps corresponding to the shape of the outer surface of the pneumatic tire. The stepped portion includes uneven portions for forming patterns and inscriptions, and saw-cut grooves that form exhaust passages. When the vent piece is arranged on the pattern and the notation, the appearance of the pattern and the notation deteriorates due to the traces of the formed vent piece. When the vent piece is arranged on the saw-cut groove, the protruding portion of the vent piece deteriorates the exhaust efficiency during vulcanization. No consideration is given to these problems in Patent Document 1.

An object of the present invention is to suppress deterioration in appearance and exhaust efficiency when arranging a vent piece on a stepped portion of a molding surface.

A first aspect of the present invention is a plurality of molds each having a molding surface including a plurality of steps corresponding to the shape of the outer surface of a pneumatic tire, and an outer surface spaced apart from the molding surface, At least one of a pair of side molds forming a side portion of the pneumatic tire has a plurality of stepped portions corresponding to a plurality of ridges and grooves extending in the tire radial direction continuously in the tire circumferential direction of the side portion. A vent hole penetrating from the molding surface to the outer surface is formed so as to correspond to at least one of each of a plurality of concave portions and convex portions, and a part of the vent hole from the molding surface is formed on the molding surface side of the vent hole. A cylindrical vent piece is attached so that the protrudes, and a notch is formed on the molding surface side of the vent piece along the concave portion and the convex portion where the vent hole is formed. Provided is a method for manufacturing a tire vulcanization mold, in which a widened portion is formed on a molding surface side so as to gradually widen from the outer surface toward the molding surface.

According to this tire vulcanization mold, since the vent piece is provided with notches along the shape of the concave portion and the convex portion, which are step portions corresponding to the shape of the outer surface of the side portion of the pneumatic tire, The unevenness of the notch can compensate for the stepped portion of the mold. Therefore, in the case where the stepped portion is a concave-convex portion forming a notation and a pattern, it is possible to suppress deterioration in appearance of the molded pattern and notation.

In addition, on the molding surface side of the vent piece, a widened portion that gradually expands from the outer surface toward the molding surface is formed. It is possible to prevent the rubber that has flowed into the vent piece from remaining in the vent piece due to breakage.

In the present invention, since the vent piece is provided with a notch along the shape of the step corresponding to the shape of the outer surface of the pneumatic tire, the appearance of the pneumatic tire is deteriorated and the exhaust efficiency during vulcanization is reduced. can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the tire vulcanization molding machine using the tire vulcanization mold which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view showing the tire vulcanizing machine in a mold open state; Schematic diagram of a pneumatic tire molded by a tire vulcanization molding machine. Sectional drawing which shows the exhaust structure of a metal mold|die. The front view which shows the exhaust structure provided in the step part of side mold. BB line cross-sectional view of FIG. 4A. 4C is a perspective view of FIG. 4B; FIG. FIG. 4 is a perspective cross-sectional view showing the manufacturing process of the mold; FIG. 4 is a perspective cross-sectional view showing another manufacturing process of the mold; FIG. 4 is a perspective cross-sectional view showing another manufacturing process of the mold;

Embodiments of the present invention will be described below with reference to the drawings.

1A and 1B show a tire vulcanizing machine (hereinafter abbreviated as "vulcanizing machine") 10 using a tire vulcanizing mold (hereinafter referred to as "mold") 50 according to an embodiment of the present invention. show. The mold 50 includes a sector mold 51, an upper mold (side mold) 52, and a lower mold (side mold) 54 for molding the pneumatic tire 1 shown in FIG. is attached to the container 30 of the

(Overview of vulcanization molding machine)
As shown in FIG. 1A, vulcanization molding machine 10 comprises frame 20, container 30, bladder unit 40, and mold 50 of the present invention. The bladder unit 40 and the mold 50 define a cavity for vulcanizing the green tire 1'. By driving the frame 20 by a drive mechanism (not shown), the mold 50 is switched between the clamped state shown in FIG. 1A and the mold opened state shown in FIG. 1B.

As shown in FIGS. 1A and 1B, frame 20 includes plate 21 , upper platen 22 and lower platen 23 .

Plate 21 is fixed to the lower end of lifting member 24 . The upper platen 22 is fixed to the lower end of an elevating member 25 arranged in the center of the elevating member 24 . The lower platen 23 is fixed at a predetermined position below the upper platen 22 . The elevating members 24 and 25 each have a drive mechanism, and elevate the plate 21 and the upper platen 22 independently. The upper platen 22 has a channel 22a and the lower platen 23 has a channel 23a. The mold 50 can be adjusted to a desired vulcanization temperature via the upper platen 22 and the lower platen 23 by adjusting the temperature of the heat exchange medium (for example, oil) flowing through these flow paths 22a and 23a.

With continued reference to FIGS. 1A and 1B, container 30 comprises a plurality of segments 31 , jacket 32 , upper plate 33 and lower plate 35 .

The segments 31 are provided in the same number as the plurality of sectors 51A constituting the sector mold 51, and each sector 51A is screwed. The outer surface of the segment 31 in the radial direction X of the sector mold 51 is composed of an inclined surface 31a that gradually widens (inclines) downward from above. The plurality of segments 31 are respectively attached to a plurality of upper slides 34 fixed to the upper plate 33 and are reciprocally movable in the radial direction X with respect to the upper slides 34 .

The jacket 32 has a cylindrical shape capable of covering the outer periphery of the mold 50 in the open state shown in FIG. 1B and is fixed to the lower surface of the plate 21 . The jacket 32 moves up and down via the plate 21 according to the up-and-down motion of the elevating member 24 . When the plate 21 descends, the jacket 32 presses the inclined surface 31a with the inclined surface 32a located inside in the radial direction X, moving the segments 31 inward in the radial direction X, and connecting the plurality of segments 31 in a ring shape. be arranged (side by side).

The upper plate 33 is fixed to the lower surface of the upper platen 22 and moves up and down via the upper platen 22 according to the up-and-down motion of the elevating member 25 . An upper slide 34 is fixed to the outer periphery of the upper plate 33, and an upper mold 52 is fixed to the inner side thereof. The lower plate 35 is fixed to the upper surface of the lower platen 23 . A lower slide 36 is fixed to the outer periphery of the lower plate 35, and a lower mold 54 is fixed to the inner side thereof.

1A and 1B, the bladder unit 40 includes a spindle 41, an upper clamp 42, a lower clamp 43, and a bladder 44. As shown in FIG.

The support shaft 41 is arranged at the center of the lower platen 23 and has a rod 41a that can be raised and lowered in the width direction (axial direction) Y of the sector mold 51 by a drive mechanism (not shown). The upper clamp 42 is fixed to the rod 41a, and the lower clamp 43 is fixed to the main body of the support shaft 41. As shown in FIG. The interval in the width direction Y between the upper clamp 42 and the lower clamp 43 is adjusted by raising and lowering the rod 41a by driving the drive mechanism. The bladder 44 has an upper inner peripheral edge attached to the upper clamp 42 and a lower inner peripheral edge attached to the lower clamp 43 . Air is supplied to and discharged from the space surrounded by the upper clamp 42, the lower clamp 43, and the bladder 44 by an air supply/exhaust device (not shown). The bladder 44 is inflated by being supplied with air, and supports the green tire 1' from the inner side in the tire radial direction.

(Outline of tire vulcanization mold)
With continued reference to FIGS. 1A and 1B, mold 50 comprises sector mold 51, top mold 52, and bottom mold 54, as previously described.

The sector mold 51 includes sectors 51A each having a fan shape in a plan view and formed by dividing an annular body into a plurality (seven in this embodiment) in the circumferential direction Z, which are attached to the segments 31, respectively. In the clamped state shown in FIG. 1A, a plurality of sectors 51A are arranged in an annular shape with an inner diameter corresponding to the outer diameter of the tire to be molded. In the radial direction X of the sector mold 51, the inner surface of the sector 51A forms a molding surface 51a for molding the tread portion 2 (see FIG. 2) of the pneumatic tire 1, and the outer surface of the sector 51A forms a molding surface 51a for attaching to the segment 31. It constitutes the mounting surface 51b. The molding surface 51 a has a stepped portion corresponding to the shape of the outer surface of the tread portion 2 .

The upper mold 52 has an annular shape and is fixed to the lower surface of the upper plate 33 so as to be positioned above the green tire 1'. The upper mold 52 moves up and down via the upper plate 33 according to the up-and-down motion of the elevating member 25 . An upper bead ring 53 is fixed to the inner peripheral portion of the upper mold 52 . The inner surface of the upper mold 52 located on the lower side in FIGS. 1A and 1B constitutes a molding surface 52a for molding one of the pair of side portions 3 (see FIG. 2) of the tire 1, and the upper bead ring The inner surface of 53 constitutes a molding surface 53a for molding one of the pair of bead portions 4 (see FIG. 2) of the tire 1. As shown in FIG. The molding surface 52 a has a stepped portion corresponding to the shape of the outer surface of one side portion 3 . The outer surface of the upper mold 52 located on the upper side in FIGS. 1A and 1B forms a mounting surface 52b for mounting to the upper plate 33, and the outer surface of the upper bead ring 53 forms a mounting surface 53b for mounting to the upper mold 52. Configure.

The lower mold 54 has an annular shape like the upper mold 52, and is fixed to the upper surface of the lower plate 35 so as to be positioned below the green tire 1'. A lower bead ring 55 is fixed to the inner peripheral portion of the lower mold 54 . The inner surface of the lower mold 54 located on the upper side in FIGS. 1A and 1B constitutes a molding surface 54a for molding the other of the pair of side portions 3 of the tire 1, and the inner surface of the lower bead ring 55 is A molding surface 55a for molding the other of the pair of bead portions 4 of the tire 1 is formed. The molding surface 54 a has a stepped portion corresponding to the shape of the outer surface of the other side portion 3 . The outer surface of the lower mold 54 located on the lower side in FIGS. 1A and 1B forms a mounting surface 54b for mounting to the lower plate 35, and the outer surface of the lower bead ring 55 forms a mounting surface 55b for mounting to the lower mold 54. configure.

In the mold 50 configured in this way, the green tire 1 ′ is placed on the lower mold 54 in the opened state shown in FIG. In this state, air is supplied to inflate the bladder 44, and in a state in which the inner surface of the green tire 1' is held by the outer surface thereof, the lifting members 24 and 25 are lowered by driving the drive mechanism, thereby allowing the air to flow in FIG. 1A. The mold 50 is clamped as shown in .

The rubber of the green tire 1' adheres to the molding surfaces 51a to 55a by pressing from the mold 50. As shown in FIG. A heat exchange medium adjusted to a predetermined temperature is constantly flowing between the upper platen 22 and the lower platen 23 . As a result, the rubber of the green tire 1' is vulcanized, and the pneumatic tire 1 having the prescribed outer surface shape shown in FIG. 2 is completed.

A rib portion (not shown) formed on the molding surface 51a of the sector mold 51 forms a groove (not shown) having a predetermined shape on the outer surface in the tire radial direction of the tread portion 2 of the tire 1. . The stepped portions (uneven portions) formed on the molding surfaces 52a and 54a of the upper mold 52 and the lower mold 54 provide the side portion 3 of the tire 1 with a pattern for improving rigidity or design and the notation of the tire 1. molded.

For example, on the side portion 3 of the tire 1 shown in FIG. 2, a plurality of ridges 5 extending in the tire radial direction are provided at intervals in the tire circumferential direction as a functional pattern for improving the rigidity in the tire radial direction. A recessed line 6 is formed between adjacent projected lines 5 . 4A to 4C, molding surfaces (profile surfaces) 52a and 54a of the upper mold 52 and the lower mold 54 have concave portions 56 for forming the ridges 5 and convex portions for forming the ridges 6. 57 are formed, respectively, and a stepped portion is formed by these.

During vulcanization, if air or gas generated from the rubber composition remains in the mold 50, the rubber will not adhere to the molding surfaces 51a to 55a, and bares will occur on the tire surface or inside the tire 1. Air entrapment (cavities) may occur. Therefore, among the sector mold 51, the upper mold 52, the upper bead ring 53, the lower mold 54, and the lower bead ring 55, an exhaust structure for discharging air and gas is provided in the portion where the rubber flow is poor. .

FIG. 3 shows an exhaust structure formed in the sector mold 51. As shown in FIG. This exhaust structure has a vent hole 60 penetrating from the molding surface 51a to the mounting surface 51b (outer surface) to allow air and gas to flow from the inside of the mold 50 to the outside. A vent piece 61 is attached to the molding surface 51a side of the vent hole 60 . The vent piece 61 is a cylindrical member having a vent hole 61a, and is attached so that a widened portion 61b formed at one end is positioned on the molding surface 51a side. Such an exhaust structure is also formed in the upper mold 52, the upper bead ring 53, the lower mold 54, and the lower bead ring 55 as well.

Saw-cut grooves 58 (see FIG. 4A) forming exhaust passages are formed in the upper mold 52 and the lower mold 54 in order to guide the air in the mold 50 to the vent holes 60 and discharge it efficiently. The saw cut grooves 58 are formed in the molding surfaces 52a and 54a so as to be recessed outward in the width direction Y, and the outer surface of the tire 1 is formed with a protruding portion (see FIG. 2) 7 protruding in a semicircular shape corresponding to the saw cut grooves 58. be done.

Conventionally, when a vent hole is provided so as to straddle a concave portion and a convex portion, the vent piece protruding from the molding surface impairs the appearance of the pattern of the side portion and the notation. When the vent hole is provided on the saw-cut groove, part of the vent piece protruding from the saw-cut groove reduces the exhaust efficiency during vulcanization. In order to suppress such inconvenience, the vent piece 61 is configured as follows in this embodiment.

(Details of exhaust structure)
4A to 4C show an example in which a vent hole 60 is formed across the concave portion 56 and the convex portion 57 in the upper mold 52 and the lower mold 54. FIG. In the following description, the upper mold 52 and the lower mold 54 are collectively referred to as side molds.

4A to 4C, the side molds 52 and 54 are provided with vents extending from molding surfaces 52a and 54a in which concave portions 56 and convex portions 57 are formed to mounting surfaces 52b and 54b (see FIG. 1A). A hole 60 is provided. A vent piece 61 is attached to the forming surfaces 52 a and 54 a of the vent hole 60 , and a notch 62 is formed in the vent piece 61 along the shapes of the concave portion 56 and the convex portion 57 .

Specifically, the vent hole 60 is formed with a diameter that includes part of the second protrusions 57b located on both sides of the first protrusion 57a. The notch 62 of the vent piece 61 is formed along the shape of the projections 57a, 57b and the recess 56a therebetween. Due to the notch 62, the vent piece 61 is formed with a concave portion 63 that continues to the concave portion 56a, a convex portion 64 that continues to the convex portion 57a, and a convex portion 65 that complements the missing portion of the convex portion 57b. .

As shown most clearly in FIG. 4B, the recess 63 of the vent piece 61 has the same shape as the recess 56a of the side molds 52, 54 when viewed from the direction in which the recess 56 and the projection 57 extend, and the extension of the recess 56a function as The convex portion 64 of the vent piece 61 has the same shape as the convex portion 57a of the side molds 52 and 54, and functions as an extension of the convex portion 57a. The convex portion 65 of the vent piece 61 has a shape that complements the missing portion of the convex portion 57b of the side molds 52 and 54 due to the formation of the vent hole 60, and forms one convex line together with the remaining portion of the convex portion 57b. .

On the side of the notch 62 of the vent piece 61, a widening portion 66 is formed that gradually widens from the mounting surfaces 52b, 54b toward the molding surfaces 52a, 54a. This widening portion 66 is provided in place of the widening portion 61b removed by forming the notch 62. As shown in FIG. In other words, the vent piece 61 having the notch 62 does not have the enlarged portion 61b (see FIG. 3) provided in advance. The expanded portion 66 is formed so that the opening located on the same plane as the recessed portion 63 has a predetermined diameter required for exhaust.

The outer diameter D1 of the vent piece 61 (the inner diameter of the vent hole 60) is 1.5 mm to 3.2 mm, and the diameter D2 of the vent hole 61a of the vent piece 61 is 0.5 mm to 1.0 mm. The diameter D3 of the largest portion of the expanded portion 66 is the same as the diameter of the largest portion of the expanded portion 61b, and is 1.4 mm to 2.0 mm. The vent piece marks formed on the conventional tire without the notch 62 consist of a circular dent corresponding to the outer diameter D1 of the vent piece 61 and a conical projection with a maximum diameter D3 protruding from the center of the dent. and a spew with a diameter of D2 protruding from the top of this projection. On the other hand, in the present embodiment in which the vent piece 61 is provided with the notch 62 (the concave portion 63 and the convex portions 64 and 65), as shown in FIG. It consists of a conical protrusion 8a with a maximum diameter of D3 and a spew 8b with a diameter of D2 protruding from the top of the protrusion. That is, in the exhaust structure of this embodiment, the recess corresponding to the outer diameter D1 of the vent piece 61 can be eliminated.

As described above, in the mold 50 of the present embodiment, the notches 62 along the shapes of the concave portion 56 and the convex portion 57 are provided in the vent piece 61, so that the concave/convex portions 63 to 65 form the molding surfaces 52a and 54a. It is possible to compensate for the uneven portions (stepped portions) 56 and 57 of the . Therefore, the vent piece marks 8 formed on the tire 1 can be minimized. As a result, it is possible to suppress deterioration of the appearance of the pattern and the description formed on the tire 1 due to the vent piece marks 8 . Further, when the exhaust structure is provided on the saw-cut groove 58, the portion protruding into the saw-cut groove 58 is removed by the notch 62, so that a decrease in exhaust efficiency can be prevented. You can prevent it from being damaged. As a result, the pneumatic tire 1 with excellent appearance can be reliably molded.

Next, a method for manufacturing the mold 50 will be described with reference to FIGS. 5A to 5C.

When the exhaust structure is provided in the portions of the side molds 52 and 54 where the concave portion 56 and the convex portion 57 are formed, first, as shown in FIG. do. Subsequently, as shown in FIG. 5B, the vent piece 61 is driven from the molding surfaces 52a and 54a. At this time, conventionally, the end of the vent piece 61 had to be driven in until it was flush with the top of the projection 57, but in the present embodiment, it may protrude from the projection 57 as shown in the drawing.

Subsequently, as shown in FIG. 5C, the portions of the vent piece 61 protruding from the concave portion 56 and the convex portion 57 are cut to form a notch 62 having edges along the shapes of the concave portion 56 and the convex portion 57 . As a result, a concave portion 63 continuing to the concave portion 56a, a convex portion 64 continuing to the convex portion 57a, and a convex portion 65 supplementing the missing portion of the convex portion 57b are formed. compensated. In addition, the pre-provided expanding portion 61b is removed.

Finally, as shown in FIG. 4C, the notch 62 side of the vent piece 61 is cut around the axis of the air hole 61a to form a new conical expanded portion 66. As shown in FIG. The same applies to the formation of the exhaust structure on the saw-cut grooves 58 of the side molds 52 and 54 .

In this manner, since the vent piece 61 is formed with the widened portion 66 after the notch 62 is formed, it is possible to reliably prevent a decrease in exhaust efficiency during vulcanization. Moreover, when the mold is opened after vulcanization, the spew that has flowed into the vent piece 61 is broken by the conical projection formed by the expanded portion 66 and can be prevented from remaining in the vent piece 61 . Therefore, the maintainability of the mold 50 can also be improved.

The tire vulcanizing mold 50 of the present invention and the manufacturing method thereof are not limited to the configuration of the above-described embodiment, and various modifications are possible.

For example, it is possible to change the pattern and notation by means of stepped portions (uneven portions) as necessary. Moreover, the part where the exhaust structure having the vent piece 61 including the notch 62 is provided may be only the upper mold 52 or only the lower mold 54 . Moreover, when providing an exhaust structure in the skeleton (stepped portion) of the sector mold 51 forming the tread portion 2 , a notch 62 may be provided in the vent piece 61 attached to the vent hole 60 . Further, when saw-cut grooves are formed in the molding surfaces 53a, 55a of the bead rings 53, 55 and an exhaust structure is provided on the saw-cut grooves, a notch 62 may be provided in the vent piece 61 attached to the vent hole 60 thereof.

The mold 50 may be a two-piece mold including a pair of molds obtained by dividing the annular (mold clamped) mold 50 into two in the axial direction (upper and lower). Also when providing an exhaust structure on the stepped portion of the two-piece mold, the vent piece 61 may be provided with a notch 62 having a shape corresponding to the stepped portion.

The vent piece 61 may not be provided with the expanded portion 61b in advance. Further, the step of providing the widening portion 66 is not limited to after the notch 62 is formed, and can be changed as necessary. Further, the vent piece 61 does not necessarily have to be provided with the expanding portion 66 . In this case, the vent piece mark 8 formed on the tire 1 is only the spew 8b, so that the deterioration of the appearance of the pattern and the notation can be greatly improved.

DESCRIPTION OF SYMBOLS 1'... Green tire 1... Pneumatic tire 2... Tread part 3... Side part 4... Bead part 5... Protruding line 6... Concave line 7... Protruding part 8... Vent piece mark 8a... Protrusion 8b... Spew 10... Tire vulcanization Molding machine 20 Frame 21 Plate 22 Upper platen 22a Channel 23 Lower platen 23a Channel 24 Elevating member 25 Elevating member 30 Container 31 Segment 31a Inclined surface 32 Jacket 32a Inclined surface 33 ... Upper plate 34 ... Upper slide 35 ... Lower plate 36 ... Lower slide 40 ... Bladder unit 41 ... Support shaft 41a ... Rod 42 ... Upper clamp 43 ... Lower clamp 44 ... Bladder 50 ... Tire vulcanization mold 51 ... Sector mold (mold )
51A... Sector 51a... Molded surface 51b... Mounting surface (outer surface)
52 ... Upper mold (side mold)
52a... molding surface 52b... mounting surface (outer surface)
53 ... Upper bead ring (mold)
53a... molding surface 53b... mounting surface (outer surface)
54... Lower mold (side mold)
54a... molding surface 54b... mounting surface (outer surface)
55... Lower bead ring (mold)
55a... molding surface 55b... mounting surface (outer surface)
56, 56a... Concave part 57, 57a, 57b... Convex part 58... Saw cut groove 60... Vent hole 61... Vent piece 61a... Ventilation hole 61b... Expansion part 62... Notch 63... Concave part 64... Convex part 65... Convex part 66 ...Expansion part X...Radial direction of sector mold Y...Width direction of sector mold Z...Peripheral direction of sector mold

Claims (1)

Among a plurality of molds each having a molding surface including a plurality of steps corresponding to the shape of the outer surface of the pneumatic tire, and an outer surface spaced apart from the molding surface, the side portion of the pneumatic tire is formed. In at least one of the pair of formed side molds, a plurality of recesses and protrusions, which are the plurality of stepped portions corresponding to the plurality of protrusions and recesses extending in the tire radial direction continuously in the tire circumferential direction of the side portion. Forming a vent hole penetrating from the molding surface to the outer surface so as to correspond to at least one of
A cylindrical vent piece is attached to the molding surface side of the vent hole so that a part of the vent piece protrudes from the molding surface;
After forming a notch along the concave portion and the convex portion in which the vent hole is formed, on the molding surface side of the vent piece,
A method for manufacturing a tire vulcanization mold, wherein an expanded portion that gradually expands from the outer surface toward the molding surface is formed on the molding surface side of the vent piece.

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