Tire vulcanization mold and tire manufacturing method

Abstract

To provide a tire vulcanization mold capable of reducing waste and cost, and a tire manufacturing method using the mold.SOLUTION: A tire vulcanization mold includes: a tire molding surface 1 in contact with an outer surface of the tire; a mounting groove 2 provided on the tire molding surface 1; a marker forming member 3 including a plurality of marker elements arranged in a longitudinal direction of the mounting groove 2; and a fixing member 4 that fixes the marker forming member 3 attached to the mounting groove 2. The marker forming member 3 is formed of a plurality of blocks 5 divided in the longitudinal direction of the mounting groove 2.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a tire vulcanization mold having a marking forming member attached to a tire molding surface, and a method for manufacturing a tire using the same. [Background Art]

[0002] On the outer surface of a pneumatic tire, a marking including characters and symbols indicating the tire size, manufacturer name, production year and week, and the like is formed. As a marking forming member for forming such a marking, a stencil plate (also called a serial plate) formed of a thin plate having a thickness of about 0.4 mm is known. The stencil plate is attached to the tire molding surface of a tire vulcanization mold. During vulcanization molding, an unvulcanized tire is pressed against the stencil plate, whereby the marking is formed by transfer. Such a stencil plate is described in, for example, Patent Documents 1 and 2.

[0003] A stencil plate is produced by stamping a marking configured by arranging a plurality of marking elements (for example, characters) on a single metal plate. When updating the tire marking, the stencil plate is replaced, and the used stencil plate is discarded. Normally, since the marking includes the production year and week, replacement is required at least every week, and the stencil plate is discarded each time. For this reason, there has been a problem that waste increases. In addition, it is necessary to produce a number of stencil plates corresponding to the update frequency of the marking, which tends to increase the cost. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Laid-Open Publication No. 2005-88517 [Patent Document 2] Japanese Patent Laid-Open Publication No. 2014-172360 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] This disclosure is made in view of the above circumstances, and its purpose is to provide a tire vulcanization mold that can reduce waste and costs, and a method for manufacturing tires using the same. [Means for solving the problem]

[0006] The tire vulcanizing mold of this disclosure comprises a tire molding surface in contact with the outer surface of a tire, a mounting groove provided on the tire molding surface, a marking member including a plurality of marking elements arranged in the longitudinal direction of the mounting groove, and a fixing member for fixing the marking member mounted in the mounting groove, wherein the marking member is formed of a plurality of blocks divided in the longitudinal direction of the mounting groove.

[0007] The tire manufacturing method of this disclosure includes a step of vulcanizing and molding a tire using the tire vulcanization mold described above. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic cross-sectional view showing an example of a tire vulcanization mold according to this disclosure. [Figure 2] Perspective view along the X-arrow in Figure 1 [Figure 3] Cross-sectional view taken along arrow AA in Figure 2 [Figure 4] Cross-sectional view taken along arrow BB in Figure 2. [Figure 5] Perspective view showing the sign-forming member and fixing member in disassembled form. [Figure 6] Perspective view of the block [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described with reference to the drawings.

[0010] Figure 1 shows a cross-section of the tire vulcanization mold 10 (hereinafter sometimes simply referred to as "mold 10") along the tire meridian cross-section. The mold 10 is in the closed position. The tire T is set with the tire axis oriented vertically. In Figure 1, the left direction is the outer radial direction of the tire, and the right direction is the inner radial direction of the tire.

[0011] The mold 10 comprises a tread mold portion 11 for forming the tread portion of the tire T, a pair of side mold portions 12 and 13 for forming the sidewall portion of the tire T, and a pair of bead rings 14 and 15 into which the bead portion of the tire T is fitted. The mold 10 has a tire molding surface 1 that contacts the outer surface of the tire T set in the cavity 16. The tire molding surface 1 includes the inner surface of the tread mold portion 11, the inner surfaces of the side mold portions 12 and 13, and the inner surfaces of the bead rings 14 and 15. Although not shown in the figure, the inner surface of the tread mold portion 11 is provided with irregularities for forming the tread pattern.

[0012] Examples of materials for the inner surface of the tread mold portion 11 include aluminum. This aluminum material is a concept that includes not only pure aluminum-based materials but also aluminum alloys, such as Al-Cu, Al-Mg, Al-Mg-Si, Al-Zn-Mg, Al-Mn, and Al-Si alloys. Examples of materials for the inner surfaces of the side mold portions 12 and 13 and the bead rings 14 and 15 include general structural rolled steel (e.g., SS400).

[0013] The mold 10 comprises a tire molding surface 1 that contacts the outer surface of the tire T, a mounting groove 2 provided on the tire molding surface 1, a marking member 3 that forms a mark on the outer surface of the tire T, and a fixing member 4 (not shown in Figure 1) that fixes the marking member 3 mounted in the mounting groove 2. The mounting groove 2 is provided by locally recessing a part of the tire molding surface 1, and the marking member 3 is fitted into it. In this embodiment, the mounting groove 2 is provided on the inner surface of the side mold portion 12 (an example of the tire molding surface 1).

[0014] Figure 2 is a perspective view taken along the X arrow in Figure 1, showing a portion of the inner surface of the lower side-type portion 12. A marking member 3 is mounted in the mounting groove 2, and the marking member 3 is fixed by a fixing member 4. The longitudinal direction LD of the mounting groove 2 corresponds to the tire circumferential direction, and the short direction SD of the mounting groove 2 corresponds to the tire radial direction. Furthermore, one side SD1 of the short direction SD corresponds to the outer side in the tire radial direction, and the other side SD2 corresponds to the inner side in the tire radial direction. The mounting groove 2 has an elongated shape in which the length L2 in the tire circumferential direction is greater than the width W2 in the tire radial direction. Figure 3 is a cross-sectional view taken along the AA arrow in Figure 2. Figure 4 is a cross-sectional view taken along the BB arrow in Figure 2.

[0015] A recess 31 (not shown in Figures 3 and 5) is provided on the front surface of the marking member 3 facing the cavity 16. During vulcanization molding, the outer surface of the unvulcanized tire is pressed against the front surface of the marking member 3, and a convex mark is formed by transfer. Therefore, the recess 31, when viewed from the front, is a mirror image of the mark formed on the tire T. In this example, the mark is formed by the string of characters "K6784539". That is, this mark is composed of eight marking elements: "K", "6", "7", "8", "4", "5", "3", and "9". Thus, the marking member 3 includes multiple (eight in this embodiment) marking elements arranged in the longitudinal direction LD of the mounting groove 2. Note that the marking elements are not limited to letters, but may also be symbols or figures.

[0016] Figure 5 is a perspective view showing the sign-forming member 3 and the fixing member 4 in an exploded view. In this mold 10, the sign-forming member 3 is formed of a plurality of blocks 5 divided along the longitudinal direction LD of the mounting groove 2. In this embodiment, the sign-forming member 3 is divided into eight parts, which is the number of sign elements. The sign-forming member 3 is constructed by connecting a plurality of independent blocks 5 along the longitudinal direction LD. Figure 6 is a perspective view showing a single block 5. The block 5 is made of a metal material such as stainless steel or aluminum. Each block 5 has the same shape as the others, except for the recess 31 provided on its front surface 51.

[0017] According to this configuration, when updating the marking of the tire T, it can be handled by replacing only the block 5 including the required marking element. For example, when the marking includes a 4-digit number "0712" representing the year and week of manufacture, and when updating this to "0713", the block 5 for "2" may be replaced with the block 5 for "3". Since the block 5 can be used repeatedly, the removed block 5 can be reused when it is needed in the future, which in turn can achieve reduction of waste. In addition, since the marking can be variously changed according to the combination of the blocks 5, there is no need to produce the number of marking forming members 3 corresponding to the update frequency of the marking, and cost reduction can be achieved.

[0018] In the present embodiment, the marking forming member 3 is divided such that one block 5 includes one marking element. That is, the marking forming member 3 is divided character by character (one marking element by one marking element). This increases the combination patterns of the blocks 5, so it is easy to flexibly cope with variations of the marking. However, the present invention is not limited thereto, and one block may include a plurality of marking elements. For example, the portion of the year and week of manufacture with high update frequency may be divided character by character, and the other portions may be integrated. The number of divisions of the marking forming member 3 is preferably three or more, more preferably four or more, and is further preferably the number of marking elements as in the present embodiment.

[0019] As shown in FIG. 6, the block 5 is formed in a rectangular plate shape as a whole. The block 5 has a front surface 51 facing the cavity 16, a back surface 52 facing the bottom surface 21 of the mounting groove 2 (see FIGS. 3 and 4), a side portion 53 on one side LD1 in the longitudinal direction LD, a side portion 54 on the other side LD2, a side portion 55 on one side SD1 in the lateral direction SD, and a side portion 56 on the other side SD2. The back surface 52 is in contact with the bottom surface 21 of the mounting groove 2. A thickness T5 of the block 5 (see FIG. 4) is smaller than a length L5 of the block 5 along the longitudinal direction LD, and is smaller than a width W5 of the block 5 along the lateral direction SD.

[0020] The thickness T5 of the block 5 is, for example, 1.0 mm or more, more specifically 1.0 to 2.0 mm. By having such a thickness T5, the recess 31 can be provided on the front surface 51 of the block 5, for example, by cutting using an NC machine. Therefore, the depth dimension of the recess 31 can be controlled with high accuracy, which is convenient for forming a convex mark at a required protrusion height. In contrast, in a conventional stencil plate formed of a thin plate, since the recess is embossed by embossing (relief processing), abrasion of the recess and variation in depth dimension may occur, which may hinder the formation of a convex mark at the required protrusion height.

[0021] As shown in Figures 3 and 5, the mounting groove 2 has a pair of shallow bottom portions 2S formed at both ends in the longitudinal direction LD, and a deep bottom portion 2D formed between the pair of shallow bottom portions 2S and having a larger depth than the shallow bottom portions 2S. The shallow bottom portions 2S have a relatively small depth, and the deep bottom portion 2D has a relatively large depth. The shallow bottom portion 2S is provided with a female screw hole 23 for attaching a bolt 7 described later. The mark forming member 3 is fitted into the deep bottom portion 2D. This enables appropriate positioning of each block 5 constituting the mark forming member 3 in the longitudinal direction LD. In addition, it is possible to prevent an excessively large gap between adjacent blocks 5, thereby suppressing the generation of unnecessary rubber burrs.

[0022] As shown in Figure 3, in this mold 10, one side portion 53 and the other side portion 54 of the block 5 in the longitudinal direction LD of the mounting groove 2 have complementary shapes that can be fitted to each other. According to this configuration, when the blocks 5 are connected in the longitudinal direction LD, the relative positions of adjacent blocks 5 are stable, which is convenient. In the present embodiment, the side portions 53 and 54 of the block 5 have step shapes as described later as complementary shapes that can be fitted to each other, but the configuration is not limited thereto.

[0023] In this embodiment, one of the side portions 53 and 54 of block 5 has a stepped shape where one side portion (side portion 53) protrudes from the back side of block 5, and the other side portion (side portion 54) has a stepped shape where the front side of block 5 protrudes. As a result, the side portion 54 of the adjacent block 5 fits over the side portion 53 of block 5, and the gap between adjacent blocks 5 is formed in a crank shape (see Figure 3). With this configuration, the rubber that enters the gap between adjacent blocks 5 is blocked midway, so even if rubber burrs are generated, they are less noticeable. In addition, since block 5 cannot be fitted upside down, an effect of preventing errors can also be expected.

[0024] The height h5 of the stepped surface of block 5, relative to the back surface 52, is set to substantially the same dimension as the height h2S of the shallow bottom portion 2S, relative to the bottom surface 21. As a result, the stepped surface of the lateral portion 53 that protrudes from the back side of block 5 and the shallow bottom portion 2S are substantially flush (see the lower left diagram in Figure 3), allowing the connecting portion 63 of the frame-like body 6, described later, to cover the lateral portion 53. Furthermore, the stepped surface of the lateral portion 54 that protrudes from the front side of block 5 and the shallow bottom portion 2S are substantially flush (see the lower right diagram in Figure 3), allowing the lateral portion 54 to cover the edge of the shallow bottom portion 2S. As a result, the relative position of the sign-forming member 3 (each of the blocks 5 constituting it) with respect to the mounting groove 2 can be stabilized more effectively.

[0025] The thickness T5 of block 5 is preferably 80-100%, more preferably 90-100%, of the depth D2 of the mounting groove 2 (see Figure 4). From the viewpoint of making rubber burrs caused by rubber entering the gaps between adjacent blocks 5 less noticeable, and further from the viewpoint of ensuring the strength of the protruding portion of the lateral part 53 of block 5, the height h5 of the stepped surface is preferably 40% or more of the thickness T5. Also, from the viewpoint of ensuring the strength of the protruding portion of the lateral part 54 of block 5, the height h5 of the stepped surface is preferably 60% or less of the thickness T5.

[0026] As shown in Figures 2-5, the fixing member 4 has a frame-shaped body 6 that holds the periphery of the sign-forming member 3 and a bolt 7 as a fastener. The frame-shaped body 6 is made of a metal material such as stainless steel. The frame-shaped body 6 is made of a plate material that is thinner than the block 5. The frame-shaped body 6 has a pair of extended parts 61, 62 that extend along the side wall 22 of the mounting groove 2, and a pair of connecting parts 63, 64 that connect them at both ends in the longitudinal direction LD. There is a window-like opening between the pair of extended parts 61, 62. Through holes 65 are formed in the pair of connecting parts 63, 64 through which the bolt 7 is inserted. The top surface of the bolt 7 protrudes from the tire molding surface 1, but it may be positioned in a recessed position from the tire molding surface 1, or it may be flush with the tire molding surface 1.

[0027] As shown in Figures 2 and 4, a mounting surface 55a is formed on the lateral portion 55 of the block 5 in the short direction SD of the mounting groove 2, recessed from the front surface 51 of the block 5, on which the frame-shaped body 6 (extended portion 61) is placed. The lateral portion 55 has a stepped shape with the back side of the block 5 protruding, and the frame-shaped body 6 (extended portion 61) is fitted into the recess formed between the lateral portion 55 and the side wall 22 of the mounting groove 2. The front surface of the frame-shaped body 6 is positioned recessed from the tire molding surface 1, but it may also be positioned flush with the tire molding surface 1. Similar to the lateral portion 55, a mounting surface 56a is formed on the lateral portion 56 on which the frame-shaped body 6 (extended portion 62) is placed.

[0028] As shown in Figure 3, the pair of connecting parts 63 and 64 are each placed on the shallow bottom section 2S. The connecting part 63 on one side LD1 in the longitudinal direction LD protrudes toward the deep bottom section 2D from the wall surface 24 that rises from the bottom surface 21 and reaches the shallow bottom section 2S, and covers the lateral part 53 of the block 5 adjacent to the shallow bottom section 2S. The connecting part 64 on the other side LD2 in the longitudinal direction LD is spaced away from the wall surface 24 in a direction away from the deep bottom section 2D so as not to obstruct the lateral part 54 of the block 5 from covering the edge of the shallow bottom section 2S. To prevent the formation of unnecessary rubber burrs, the spacing between the pair of extension parts 61 and 62, and the spacing between the pair of connecting parts 63 and 64 are set so as not to form an excessive gap between the block 5 and the frame-like body 6.

[0029] A tire manufacturing method using a tire vulcanization mold 10 includes the step of vulcanizing and molding a tire T using the mold 10, more specifically, the step of setting an unvulcanized tire in a cavity 16 and applying heat and pressure to the unvulcanized tire to perform vulcanization molding. The tire expands and deforms due to the expansion of the bladder, and its outer surface is pressed against the tire molding surface 1. After vulcanization molding, a mark is formed on the outer surface of the tire by a mark forming member 3.

[0030] In this embodiment, an example is shown in which the mounting groove 2 into which the sign-forming member 3 is attached is provided on the inner surface of the lower side mold portion 12. However, it may be provided on the inner surface of the upper side mold portion 13 instead, or in addition to this. The mounting groove 2 into which the sign-forming member 3 is attached can also be provided on the inner surface of the tread mold portion 11, or on the inner surfaces of the bead rings 14 and 15.

[0031] In this embodiment, a mold structure comprising a tread mold portion 11 and a pair of side mold portions 12 and 13 is illustrated, but the invention is not limited thereto. For example, a mold structure in which the tread mold portion is divided into two parts vertically at the center may also be used.

[0032] In this embodiment, an example is shown in which a recess 31 for forming a convex mark on the outer surface of the tire T is provided in the mark forming member 3 (each block 5), but the embodiment is not limited to this. Therefore, for example, a protrusion for forming a concave mark on the outer surface of the tire T may be provided in the mark forming member 3 (each block 5).

[0033] [1] As described above, the tire vulcanization mold 10 of this embodiment comprises a tire molding surface 1 that contacts the outer surface of the tire T, a mounting groove 2 provided on the tire molding surface 1, a marking member 3 including a plurality of marking elements arranged in the longitudinal direction LD of the mounting groove 2, and a fixing member 4 for fixing the marking member 3 mounted in the mounting groove 2. The marking member 3 is formed of a plurality of blocks 5 divided in the longitudinal direction LD of the mounting groove 2.

[0034] With this configuration, when updating the tire markings on the tire T, only the block 5 containing the required marking elements needs to be replaced. Since the removed block 5 can be reused, waste can be reduced. In addition, because the markings can be changed in various ways depending on the combination of blocks 5, there is no need to manufacture a number of marking forming members 3 corresponding to the frequency of marking updates, thus reducing costs.

[0035] [2] In the tire vulcanization mold 10 described in [1] above, it is preferable that the side portion 53 on one side and the side portion 54 on the other side of the block in the longitudinal direction LD of the mounting groove 2 have complementary shapes that can fit together. With this configuration, when the blocks 5 are connected in the longitudinal direction LD, the relative positions of adjacent blocks 5 are stable and convenient.

[0036] [3] In the tire vulcanization mold 10 described in [1] or [2] above, it is preferable that one of the side portions 53 on one side of the block 5 and the other side portion 54 has a stepped shape that protrudes from the back side of the block 5, and the other side has a stepped shape that protrudes from the front side of the block 5. With this configuration, the rubber that enters the gap between adjacent blocks 5 is blocked midway, so even if rubber burrs occur, they are less noticeable.

[0037] [4] In any one of the tire vulcanization molds 10 described in [1] to [3] above, it is preferable that the marking member 3 is divided such that each block 5 contains one of the marking elements. This increases the number of combination patterns of the blocks 5, making it easier to flexibly accommodate variations in the markings.

[0038] [5] In any one of the tire vulcanization molds 10 described in [1] to [4] above, it is preferable that the fixing member 4 has a frame-shaped body 6 that holds down the periphery of the marking member 3. This allows the marking member 3 to be held down and fixed in the mounting groove 2 without hindering the formation of the mark by the marking member 3.

[0039] [6] In the tire vulcanization mold 10 described in [5] above, it is preferable that a mounting surface 55a (56a) is formed on the side portion 55 (56) of the block 5 in the short direction SD of the mounting groove 2, which is recessed from the front surface 51 of the block 5 and on which the frame-shaped body 6 is placed. This configuration is convenient for positioning the front surface of the frame-shaped body 6 in a recessed position from the tire molding surface 1, or for positioning it flush with the tire molding surface 1.

[0040] [7] In any one of the tire vulcanization molds 10 described in [1] to [6] above, the mounting groove 2 preferably has a pair of shallow bottom portions 2S formed at both ends in the longitudinal direction LD, and a deep bottom portion 2D formed between the pair of shallow bottom portions 2S and having a greater depth than the shallow bottom portions 2S, and the marking member 3 is fitted into the deep bottom portion 2D. This allows the marking member 3 (each of the blocks 5 constituting it) to be appropriately positioned in the longitudinal direction LD.

[0041] [8] Furthermore, the tire manufacturing method of this embodiment includes a step of vulcanizing and molding a tire T using one of the tire vulcanizing molds 10 described in [1] to [7] above. By using a mold 10 as described above, it is possible to reduce waste and lower costs.

[0042] The tire vulcanization mold of this disclosure is equivalent to a conventional tire vulcanization mold, except that the marking member attached to the mounting groove on the tire molding surface is configured as described above, and any conventionally known shape, material, mechanism, etc., can be used.

[0043] The tire vulcanization mold and tire manufacturing method described herein are not limited in any way to the embodiments described above, and various improvements and modifications are possible without departing from the spirit of the invention. [Explanation of symbols]

[0044] 1. Tire molding surface 2 mounting grooves 2D deep bottom 2S shallow bottom part 3. Labeling member 4 Fixing members 5 blocks 6 Frame-like body 7. Bolts (an example of fasteners) 10 Tire vulcanization molds 16 Cavity Front of Block 51 52 Back of block 53 Side portion of the block in the longitudinal direction 54 Side portion of the block in the longitudinal direction 55 Side portion of the block in the short direction 55a Mounting surface 56 Side view of the block in the short direction 56a Mounting surface T-tire

Claims

1. The tire molding surface that contacts the outer surface of the tire, The mounting groove provided on the tire molding surface, A sign-forming member including a plurality of sign elements arranged in the longitudinal direction of the mounting groove, The system includes a fixing member for fixing the sign-forming member that is mounted in the mounting groove, The sign-forming member is formed of a plurality of blocks divided in the longitudinal direction of the mounting groove, The mounting groove has a pair of shallow bottom portions formed at both ends in the longitudinal direction, and a deep bottom portion formed between the pair of shallow bottom portions, which is deeper than the shallow bottom portions. The tire vulcanization mold is fitted into the deep bottom portion of the aforementioned marking member.

2. The tire vulcanizing mold according to claim 1, wherein one lateral portion of the block and the other lateral portion of the block in the longitudinal direction of the mounting groove have complementary shapes that allow them to fit together.

3. The tire vulcanizing mold according to claim 2, wherein one of the side portions of the block has a stepped shape that protrudes from the back side of the block, and the other has a stepped shape that protrudes from the front side of the block.

4. The tire vulcanizing mold according to claim 1, wherein the marking member is divided such that one block includes one marking element.

5. The tire vulcanizing mold according to claim 1, wherein the fixing member has a frame-shaped body that holds the periphery of the marking member.

6. The tire vulcanizing mold according to claim 5, wherein a mounting surface is formed on the side of the block in the short direction of the mounting groove, and the frame-shaped body is placed on it, recessed from the front surface of the block.

7. A method for manufacturing a tire, comprising the step of vulcanizing a tire using a tire vulcanizing mold described in any one of Claims 1 to 6.

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