JP2021079648A - Tire vulcanizing mold - Google Patents

Abstract

To provide a tire vulcanizing mold which can suppress deformation of a stencil plate and suppress occurrence of failure on the appearance of a product tire.SOLUTION: A tire vulcanizing mold 10 of the present invention includes a tire molding surface 14A for molding a tire, a mounting recessed portion 20 which is formed in a recessed shape with respect to the tire molding surface 14A, and a stencil plate 30 which is arranged in the mounting recessed portion 20 and forms marks M on a tire outer surface. The stencil plate 30 includes a flat portion 33 having a flat plate shape, and a curved portion 34 which is provided on at least a part of a peripheral edge portion of the flat portion 33. The flat portion 33 includes a mark forming portion 31 which forms the marks M on the tire outer surface, and the curved portion 34 is curved so as to approach a bottom surface 21 of the mounting recessed portion 20 toward a peripheral edge of the stencil plate 30.SELECTED DRAWING: Figure 4

Description

The present invention relates to a tire vulcanization die.

Signs such as letters, symbols or figures are provided on the outer surface of the side portion of the pneumatic tire to facilitate identification of the tire manufacturer, type, size, year of manufacture, week of manufacture and the like. In order to form such a sign, it is known that a stencil plate made of a metal plate such as aluminum or iron is replaceably attached to a side forming surface of a tire vulcanization die by a screw (see Patent Document 1 below). ..

Japanese Unexamined Patent Publication No. 2017-154282

By the way, the stencil plate is frequently replaced because the markings on the side of the pneumatic tire are changed frequently. The stencil plate may be deformed as the stencil plate is replaced repeatedly. When the stencil plate is deformed, a gap is likely to be generated between the tire vulcanizing die and the stencil plate, and unvulcanized rubber easily enters the gap during vulcanization and causes a poor appearance of the product tire.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a tire vulcanization die capable of suppressing deformation of a stencil plate and suppressing occurrence of poor appearance of a product tire.

The tire vulcanization mold according to the embodiment of the present invention has a tire molding surface for molding a tire, a mounting recess formed in a concave shape with respect to the tire molding surface, and a marking on the outer surface of the tire arranged in the mounting recess. In a tire vulcanization mold including a stencil plate forming a flat portion, the stencil plate includes a flat plate-shaped flat portion and a curved portion provided on at least a part of a peripheral portion of the flat portion, and the flat portion is provided. The tire is provided with a sign forming portion for forming a mark on the outer surface of the tire, and the curved portion is curved so as to approach the bottom surface of the mounting recess as it goes to the peripheral edge of the stencil plate.

In the above-mentioned pneumatic tire vulcanization die, deformation of the stencil plate can be suppressed, and the occurrence of poor appearance of the product tire can be suppressed.

Sectional view of tire vulcanization die of embodiment A view of the side plate of the embodiment as viewed from the inside of the mold. Perspective view showing the mounting recess, spacer and stencil plate disassembled AA sectional view of FIG. The disassembled view of the mounting recess, spacer and stencil plate of FIG. BB sectional view of FIG. CC sectional view of FIG. Partial side view of a pneumatic tire molded by the tire vulcanization die of the embodiment

FIG. 1 is a diagram showing a tire vulcanization die (hereinafter, simply referred to as a vulcanization die) 10 according to an embodiment. The vulcanization die 10 is used for vulcanizing and molding a pneumatic tire T.

Here, the pneumatic tire T includes a tread portion T1 forming a ground contact surface, and a pair of sidewall portions T2, T2 and bead portions T3, T3 extending inward in the tire radial direction from both ends in the width direction of the tread portion T1. It is configured, and a general tire structure can be adopted except for the sign provided on the sidewall portion T2.

The vulcanization die 10 is a die for setting an unvulcanized green tire and vulcanizing and molding, and forms a cavity inside which is a molding space for the tire T. The vulcanization die 10 includes a tread mold 12, a pair of upper and lower sidewall molds 14 and 14, and a pair of upper and lower bead molds 16 and 16. The tread mold 12 has a tire molding surface (tread molding surface) 12A for molding the outer surface of the tread portion T1. The pair of upper and lower sidewall molds 14, 14 have tire molding surfaces (sidewall molding surfaces) 14A, 14A for molding the outer surface of the sidewall portion T2. The pair of upper and lower bead molds 16 and 16 have a tire molding surface (bead molding surface) 16A for molding the outer surface of the bead portion T3.

As shown in FIGS. 1 to 7, the sidewall mold 14 is provided with a mounting recess 20 that is recessed with respect to the sidewall molding surface 14A. The mounting recess 20 is provided with a stencil plate 30 and a spacer 40 for forming a sign.

The mounting recess 20 is formed of a narrow recess extending while curving along the tire circumferential direction in which the length in the tire circumferential direction is larger than the width in the tire radial direction, and the mounting recess 20 is formed from the stencil plate 30 so as to be able to accept the stencil plate 30. It is provided very slightly larger. Screw holes 22 into which the fixing portions 23 are screwed are provided on the bottom surfaces 21 of both ends in the longitudinal direction (tire circumferential direction) of the mounting recess 20.

The fixing portion 23 is composed of a screw having a male screw portion to be screwed with the screw hole 22 provided in the mounting recess 20. Specifically, as shown in FIGS. 3 to 5, the fixing portion 23 has a head portion 23b having a tapered seat surface 23a (that is, a truncated cone shape) and a shaft portion provided with a male screw on the outer peripheral surface. It includes 23c.

As shown in FIG. 2, the stencil plate 30 is a narrow plate-like body that extends while being curved along the tire circumferential direction in which the length in the tire circumferential direction is larger than the width in the tire radial direction. The material of the stencil plate 30 is not limited, but is, for example, aluminum or an aluminum alloy. The thickness t1 (see FIG. 5) of the stencil plate 30 is not particularly limited, and is, for example, 0.4 to 0.6 mm.

The stencil plate 30 includes a flat plate-shaped flat portion 33, curved portions 34 provided on the peripheral edge portion of the flat portion 33, and insertion holes 35 provided at both ends in the longitudinal direction of the flat portion 33.

The flat portion 33 includes a surface 33a for molding the surface of the tire and a back surface 33b facing the bottom surface of the mounting recess 20. The label forming portions 31 are formed side by side on the surface 33a of the flat portion 33. The sign forming portion 31 is provided in a concave shape when viewed from the surface 33a side, and as shown in FIG. 8, a convex sign M is formed on the side portion of the tire T. The sign M is formed by arranging letters, symbols, figures, and the like, and represents a part or all of the manufacturer name, manufacturing factory, size, manufacturing week, manufacturing year, and the like as a whole. The label forming portion 31 has a shape in which the label M is inverted as a whole when the stencil plate 30 is viewed from the surface side.

The sign forming portion 31 is formed by recessing the flat portion 33 from the front surface 33a to the back surface 33b by press working. Therefore, a bulging portion 32 corresponding to the sign forming portion 31 appears on the back surface 33b side of the flat portion 33. The depth t2 (see FIG. 5) of the label forming portion 31 is, for example, 0.2 to 0.8 mm, and the bulging amount of the bulging portion 32 (the length in the vertical direction from the back surface of the flat portion 33 to the bulging portion 32). S) S is equivalent to the depth of the marker forming portion 31 (see FIGS. 6 and 7).

At both ends of the flat portion 33 in the longitudinal direction, receiving portions 36 for receiving the head portion 23b of the fixing portion 23 are provided. The receiving portion 36 has a tapered shape (truncated cone shape) in which the diameter gradually decreases as it approaches the back surface side (spacer 40 side). At the tip (lower end) of the receiving portion 36, a circular insertion hole 35 through which the shaft portion 23c of the fixing portion 23 is inserted is provided.

As shown in FIGS. 4 to 7, the curved portion 34 is curved so as to approach the bottom surface of the mounting recess 20 as it approaches the peripheral edge of the stencil plate 30.

The curved portion 34 is provided on the entire circumference of the flat portion 33 in the circumferential direction, and includes a first curved portion 34a provided in the central portion in the longitudinal direction and a second curved portion 34b provided at both ends in the longitudinal direction. .. The first curved portion 34a is greatly curved so as to be closer to the bottom surface 21 of the mounting recess 20 than the second curved portion 34b. That is, the bending amount of the first curved portion 34a (the length in the vertical direction from the back surface of the flat portion 33 to the tip of the first curved portion 34a) B1 is the bending amount of the second curved portion 34b (from the back surface of the flat portion 33). The curved portions 34a and 34b are curved so as to be larger than the vertical length to the tip of the second curved portion 34b) B2. B2 is not particularly limited and can be set to be smaller than the thickness t1 of the stencil plate 30, preferably 50% or less of the thickness t1. Further, it is preferable that the bending amounts B1 and B2 of the first curved portion 34a and the second curved portion 34b are smaller than the bulging amount S of the bulging portion 32.

The spacer 40 is a frame-shaped member having substantially the same shape, which is slightly smaller than the outer shape of the stencil plate 30 when viewed from the stencil plate 30 side. Insertion holes 42 through which the shaft portion 23c of the screw 23 is inserted are provided at both ends of the spacer 40 in the longitudinal direction.

As shown in FIG. 4, the spacer 40 is housed in the mounting recess 20 so as to be overlapped with the back surface side of the stencil plate 30, and is provided on the peripheral edge of the bulging portion 32 and the flat portion 33 corresponding to the sign forming portion 31. It contacts the back surface side of the flat portion 33 while avoiding the portion 34. As a result, the spacer 40 supports the stencil plate 30 so that the surface 33a of the flat portion 33 and the sidewall molded surface 14A are connected without a step.

When the stencil plate 30 and the spacer 40 are stacked and stored in the mounting recess 20, the insertion hole 35 and the insertion hole 42 are arranged coaxially with the screw hole 22 provided on the bottom surface 21 of the mounting recess 20. In this state, the shaft portion 23c of the fixing portion 23 is inserted into the insertion hole 35 and the insertion hole 42 and screwed into the screw hole 22, so that the head portion 23b of the fixing portion 23 and the bottom surface 21 of the mounting recess 20 are separated from each other. The stencil plate 30 and the spacer 40 are sandwiched.

According to the above embodiment, the stencil plate 30 is provided with a curved portion 34 that curves toward the bottom surface 21 of the mounting recess 20 toward the peripheral edge of the flat portion 33 on which the sign forming portion 31 is formed. Bending rigidity can be improved. Therefore, the deformation of the stencil plate 30 can be suppressed, and the occurrence of poor appearance of the product tire can be suppressed.

Further, according to the present embodiment, since the tip of the curved portion 34 is located in the mounting recess 20, no acutely recessed recess is formed on the outer surface of the tire T corresponding to the tip of the curved portion 34. , Cracks starting from the edge of the recess can be suppressed.

Further, in the present embodiment, when the bending amounts B1 and B2 of the first curved portion 34a and the second curved portion 34b are smaller than the bulging amount S of the bulging portion 32, the first curved portion 34a and the second curved portion 34b Corresponding protrusions are less likely to be formed on the outer surface of the tire T.

Further, in the present embodiment, when the fixing portion 23 avoids the curved portion 34 and comes into contact with the flat portion 33 to fix the stencil plate 30 in the mounting recess 20, the stencil plate is fixed even if the tightening pressure from the fixing portion 23 is received. The stencil plate 30 can be reliably fixed because the 30 is less likely to be deformed.

Further, in the present embodiment, when the curved portion 34 is provided in the central portion in the longitudinal direction of the flat portion 33, the deformable central portion in the longitudinal direction of the stencil plate 30 can be reinforced, which is caused by the deformation of the stencil plate 30. It is possible to suppress the resulting defective appearance of the product tire.

Further, in the present embodiment, the bending amount B1 of the first curved portion 34a provided at the central portion in the longitudinal direction of the flat portion 33 is the bending amount of the second curved portion 34b provided at the end portion in the longitudinal direction of the flat portion 33. When it is larger than B2, the bending rigidity of the stencil plate 30 can be made uniform and the stress concentration of the stencil plate 30 can be suppressed. As a result, the deformation of the stencil plate 30 can be suppressed, and the occurrence of poor appearance of the product tire can be suppressed.

(Change example)
The above embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention.

For example, in the above embodiment, the cross-sectional shape of the curved portion 34 is provided in an arc shape, but it may be a straight shape that bends from the flat portion 33.

Further, in the above embodiment, the case where the curved portion 34 is provided on the entire circumference of the flat portion 33 in the circumferential direction has been described, but the curved portion 34 may be provided only in the central portion in the longitudinal direction of the flat portion 33, or both ends in the longitudinal direction of the flat portion 33. The curved portion 34 may be provided at an arbitrary position in the circumferential direction of the flat portion 33, such as being provided only on the portion, being provided on the outside of the receiving portion 36, or being provided intermittently in the circumferential direction of the flat portion 33.

Further, in the above embodiment, the case where the curved portions 34a and 34b having different bending amounts are provided on the peripheral edge portion of the flat portion 33 has been described, but all of them may be set to the same bending amount or both ends in the longitudinal direction of the flat portion 33. The bending amount may be changed so as to gradually increase or gradually decrease from the center to the center.
Further, in the above-described embodiment, the stencil plate 30 and the mounting recess 20 are provided on the sidewall molding surface 14A, but may be provided on the bead molding surface 16A, and the sidewall molding surface 14A and the bead molding surface 16A may be provided. It may be provided on both sides of the above.

10 ... Tire vulcanization mold, 12 ... Tread mold, 14 ... Side wall mold, 16 ... Bead mold, 18 ... Side mold, 20 ... Mounting recess, 21 ... Bottom surface, 22 ... Bolt, 23 ... Fixed part, 30 ... Stencil Plate, 31 ... Label forming portion, 32 ... Swelling portion, 33 ... Flat portion, 33a ... Front surface, 33b ... Back surface, 34 ... Curved portion, 35 ... Insertion hole, 40 ... Spacer, 42 ... Insertion hole

Claims (4)

In a tire vulcanization die including a tire molding surface for molding a tire, a mounting recess formed in a concave shape with respect to the tire molding surface, and a stencil plate arranged in the mounting recess and forming a sign on the outer surface of the tire.
The stencil plate includes a flat plate-shaped flat portion and a curved portion provided on at least a part of the peripheral edge portion of the flat portion.
The flat portion includes a sign forming portion for forming a sign on the outer surface of the tire.
The curved portion is a tire vulcanization die that curves so as to approach the bottom surface of the mounting recess as it goes to the peripheral edge of the stencil plate. A fixing portion for fixing the stencil plate is provided in the mounting recess.
The tire vulcanization die according to claim 1, wherein the fixed portion abuts on the stencil plate at the flat portion. The tire vulcanization die according to claim 1 or 2, wherein the stencil plate is made of a narrow plate-like body, and the curved portion is provided at least in the central portion in the longitudinal direction. The curved portion includes a first curved portion provided at the central portion in the longitudinal direction of the stencil plate and a second curved portion provided at the end portion in the longitudinal direction of the stencil plate.
The tire vulcanization die according to claim 3, wherein the first curved portion is greatly curved so as to be closer to the bottom surface of the mounting recess than the second curved portion.

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