JP3895309B2 - Manufacturing method of tire molding die and tire molding die manufactured by the manufacturing method - Google Patents

Description

  The present invention relates to a tire molding die manufactured by a casting method. More specifically, in a split mold for molding a tire (two-piece mold), the two split molds are arranged vertically with the split position surfaces facing each other, and cast as a single ring casting, The present invention relates to a method for manufacturing a split mold for molding a tire and a tire molding mold manufactured by the manufacturing method, wherein a cast product after casting is separated into upper and lower molds by machining or the like.

  Tire molding dies have many shapes that are difficult to deal with by machining, that is, a concave block shape with sharp corners and a thin convex shape called a sipe blade. There are many. At this time, the sipe blade often responds by “casting” the tire mold body.

  Moreover, it can be said that the gypsum casting method is often used among the casting production methods. This is because the mold is collapsible, has a high degree of freedom in supporting undercut shapes, can be easily assembled with the mold, can be cast into a nearly integral shape, and has high dimensional accuracy. The reason is that the mold cost is low.

  Other than the gypsum casting method, there are a ceramic mold method and a die casting method, but it can be said to be a minority (see Non-Patent Document 1).

  The tire molding die manufacturing method using the gypsum casting method is divided into two-piece molds (upper and lower split molds) that divide the tire shape into two in the width direction, and about 7 to 13 in the circumferential direction. It is roughly divided into two types: sectional mold (upper and lower integrated type).

  The two-piece mold has the advantage that the mold cost is low because the number of mold divisions is small and the mold structure is simple. On the other hand, when removing the molded tire from the mold, There is a demerit that it is easy to form an undercut due to the protrusion shape (bone or sipe blade) of the mold design surface, and that it is difficult to remove the mold for a complicated design. In order to overcome this problem and to have an advantage in terms of dimensional accuracy, a sectional mold is used.

  FIG. 16 shows a procedure for producing a two-piece mold by a gypsum casting method. First, a tire mold (master model) 1 is produced by machining using gypsum, resin or the like as shown in (a), and a rubber mold 2 in which the prototype 1 is inverted with silicone rubber or the like as shown in (b). Is made. Then, as shown in (c), the sector 3 obtained by dividing the rubber mold 2 into upper and lower parts is inverted by gypsum, and this sector 3 is baked and dried, and then cut at a plurality of angles as shown in (d). The ring-shaped mold 4 is assembled as shown in FIG. Then, as shown in (f), the mold 4 is surrounded by a casting frame 5 and cast into a casting by filling the casting frame 5 with a molten alloy 6 such as an aluminum alloy. Then, machining is performed, and then mold matching is performed as shown in (g) to obtain a tire molding die 8. In (g), reference numeral 7 denotes a plurality of pieces constituting the tire molding die 8, and the tire molding die 8 is produced by assembling in a ring shape using a backup material (not shown). Is.

  FIG. 17 shows a procedure for producing a sectional mold by a gypsum casting method. Similarly to FIG. 16, after producing a rubber mold 2 of (b) in which the original form 1 of the tire shown in (a) is reversed, (c) And, as shown in (d), sector 3 is made of gypsum and assembled as shown in (e) to form a mold 4. Thereafter, as in FIG. 16 (f), casting with a cast metal such as an aluminum alloy is performed, and the casting is matched to form a tire molding die 8 shown in FIG. 16 (f).

  As described above, it can be said that the tire mold 8 is usually manufactured by assembling the gypsum mold 4 in a ring shape, surrounding it with the casting frame 5, and casting it.

  At this time, the two-piece mold type requires two casting steps of casting the upper and lower rings in order to obtain the tire molding die 8 for one set (one set of upper and lower sides). .

  By the way, the dimensional accuracy required for the tire mold is determined by the dimensional accuracy of each part of the tire which affects the running performance of the tire.

  Quantitative evaluation of tire running performance is often performed by the following uniformity confirmation test. Uniformity (referred to as UF for short) refers to the force generated during one rotation of the tire under load and the magnitude of the fluctuation, and the components of the force in the three axial directions shown in FIG. It expresses by. In FIG. 18, the symbol TY is a tire and the symbol DR is a rotating drum.

  That is, in FIG. 18, the force components in the three-axis directions are radial force (RFV, abbreviation of Radial Force Variation), front-rear direction force (TFV, abbreviation of Tractive Force Variation), and tire width direction. Force (abbreviation of LFV, Lateral Force Variation) and force that prevents straight travel (abbreviation of CON, Connectivity).

  Here, the radial force (RFV) is a change width of a vertical reaction force generated on the tire TY and the ground contact surface (drum DR) when the tire TY is rotated by applying a constant load. The main causes of the vertical runout and the vertical stiffness fluctuation of the tire TY are generated. The force in the front-rear direction (TFV) is the change width of the reaction force in the advancing (tangential) direction generated on the tire TY and the ground contact surface (drum DR) when the tire TY is rotated with a constant load. Although it is easily affected by the sector division plane of the sectional mold, it has been theorized that there is almost no influence if the pitch is divided to the piece division level. The force in the tire width direction (LFV) is the change width of the reaction force in the lateral direction (tire width direction) generated on the tire TY and the ground contact surface (drum DR) when the tire TY is rotated with a constant load. This is mainly due to the lateral deflection and lateral stiffness fluctuation of the tire TY. The force that prevents straight travel (CON) is the difference (1/2) in the average value of reaction forces generated in the same axial direction when the tire TY is rotated forward and reverse with a constant load. The main cause of this is that the left and right shapes are different.

  In this way, the factors that determine the tire uniformity are the uniformity of the rubber thickness of the “green tire” before it is molded in the mold, the axial symmetry, the concentricity when setting the green tire mold, etc. It can be said that the degree of influence due to variations in the tire manufacturing process is extremely large.

  However, in recent years, variations in the tire manufacturing process have been considerably reduced, and accordingly, the degree of influence of dimensional accuracy on the mold side for molding the tire is increasing.

ここで、真円度特性とは、図１９（ａ）に示すように、基準真円Ｒからの振れ特性で、最大振れ幅（Ｒｍａｘ）で示している。芯ずれ特性Ｉは、図１９（ｂ）に示すように、タイヤとホイールとの芯ずれ特性である。芯ずれ特性ＩＩは、図１９（ｃ）に示すように、タイヤの上下型間（模式図では左右間）の芯ずれ特性である。芯ずれ特性Ｉ，IIが、タイヤ回転時の真円度特性（RRO、Rａｄｉａｌ Rｕｎ−Oｕｔの略）の悪化と言う形で現われることになる。芯ずれ特性ＩによるRROは、芯ずれ幅Rｅの２倍、芯ずれ特性IIによるRROも芯ずれ幅Lｅの２倍で表わされる。この芯ずれ特性ＩＩは、２Pモールドの場合、加硫機への組み込み後の「インロー」噛み合わせずれの影響も受けやすい。 Therefore, Table 1 shows the dimensional characteristics of the tire mold that affect the tire uniformity. Table 1 shows the mold accuracy guarantee items for improving the UF level. The roundness characteristics, the radius difference characteristics I and II of each part, the upper and lower mold diameter difference characteristics, and the buttress part protrusion characteristics are shown as items to be guaranteed. Select each characteristic, mold type (2P (2-piece mold type), Sec. (Sectional mold)), and influence on UF (RFV (radial force), LFV (force in the tire width direction) , CON (the force that prevents straight travel)), the degree of appearance of a bad influence on each factor. Table 1 also includes a column for standard examples (mold characteristics).

Here, the roundness characteristic is a vibration characteristic from the reference perfect circle R, as shown in FIG. 19A, and is represented by a maximum fluctuation width (Rmax). The misalignment characteristic I is a misalignment characteristic between the tire and the wheel, as shown in FIG. The misalignment characteristic II is a misalignment characteristic between the upper and lower molds of the tire (between left and right in the schematic diagram), as shown in FIG. The misalignment characteristics I and II appear in the form of deterioration of roundness characteristics (RRO, abbreviated to Radial Run-Out) during tire rotation. The RRO due to the misalignment characteristic I is represented by twice the misalignment width Re, and the RRO due to the misalignment characteristic II is also represented by twice the misalignment width Le. This misalignment characteristic II is also easily affected by the “in-law” misalignment after incorporation into the vulcanizer in the case of the 2P mold.

  Further, as shown in FIG. 19 (d), the upper and lower die diameter difference characteristics are such that the influence of the mold appears in the tire straightforwardly, and the diameter difference between the upper die side tire diameter D1 and the lower die side tire diameter D2 ( = D1-D2). As shown in FIG. 19E, the buttress portion protrusion characteristic is indicated by the maximum value of the thickness Ta of the protrusion piece a (Ta = Max value).

  As described above, when the mold for tire molding is considered from the viewpoint of tire uniformity with the design surface mold part alone, as shown in Table 5, roundness characteristics and misalignment characteristics at the top and bottom of the tire mold It can be seen that II and the upper and lower die diameter difference characteristics are very important characteristic values.

先ず、真円度特性について、図２０に基づいて説明する。 Qualitative comparison of these tire mold dimensional characteristics between the two-piece mold type and the sectional mold type is as shown in Table 2. Both characteristics are sectional in terms of tire uniformity. It can be said that the mold is more advantageous. This is due to the following reason.

First, the roundness characteristic will be described with reference to FIG.

  As shown in FIG. 20 (a), in the state of a ring casting, when the radius (diameter) is out of the target dimension (normal radius R) and the roundness characteristic is not good, in the two-piece mold, unless corrected by external force, It will be used as a mold in this state. On the other hand, in the sectional mold by the end face surplus setting method, as shown in FIG. 20 (b), after dividing the sector, both ends of the circumferential direction Pf surface are set to the positions of the regular radii R and the same between the upper and lower molds. Peripheral machining can be performed by adjusting the position of the sector so that the radius is the same (as in all sectors). Therefore, in the sectional mold, both ends of the sector can be shifted to the position of the normal radius R (as shown in FIG. 20 (c), before the sector position adjusting process → after the sector position adjusting process), so both the diameter and the roundness are obtained. Improved from the ring state.

  Next, the misalignment characteristic II will be described with reference to FIG.

  As shown in FIG. 21 (a), in the two-piece mold type, the upper and lower molds 8a and 8b are individually casted and the upper and lower molds are aligned by processing. It tends to occur. On the other hand, as shown in FIG. 21B, in the sectional mold type, since the upper and lower molds are integrated and cast as the mold 8, there is a possibility that misalignment between the upper and lower molds may occur during processing. Low.

  Further, the upper and lower mold diameter difference characteristics will be described from the viewpoint of the average diameter difference between the upper and lower molds (based on FIG. 22) and from the viewpoint of the difference in roundness tendency between the upper and lower molds (based on FIG. 23). .

  As shown in FIG. 22 (a), in the two-piece mold type, the upper and lower molds 8a and 8b are separately cast, so that the average diameter (upper φD, lower φD) tends to be different between the upper and lower molds. This is easily connected to the “upper and lower die diameter difference”. On the other hand, as shown in FIG. 22 (b), in the sectional mold, the upper and lower molds are integrated and cast as a mold 8, and the sector block radius can be adjusted at the time of processing. Therefore, it is difficult to cause an average diameter difference between the upper and lower molds.

  In addition, as shown in FIG. 23 (a), in the two-piece mold type, the upper and lower dies 8a and 8b are separately cast, so that an average diameter difference is easily generated between the upper and lower dies, and true between the upper and lower dies. The tendency of circularity is often different. For this reason, the upper and lower die radius difference (Δθ) at each portion (position of angle θ) tends to be even larger. On the other hand, as shown in FIG. 23B, in the sectional mold, since the upper and lower molds are integrated and cast as the mold 8, the tendency of roundness tends to be the same between the upper and lower molds. In addition, since the average diameter difference between the upper and lower molds is small, the vertical mold radius difference (Δθ) at each portion (position of the angle θ) is unlikely to be a large value.

  Also, from a viewpoint different from the dimensional accuracy, the two-piece mold has a lower degree of freedom in dealing with an undercut shape (with a reverse draft) than the sectional mold, compared to the sectional mold. Not suitable for complicated designs.

  In addition, in the case of a two-piece mold, the outer periphery of the ring casting is performed by a lathe, a milling machine, etc., so that the surface (dividing surface, PL surface) that divides the mold up and down must be made planar. In many cases, there is a limit in setting the divided surface while avoiding the design of the mold design surface (such as cast bone and cast-in sipe blade).

  In other words, in the case of a two-piece mold, if the cast bone and cast-in sipe blades exist across the divided surfaces, a large load is applied to this part when the mold is opened and closed or the molded tire is removed. It is easy to start, and it is easy to cause troubles such as breakage, and it is easy to cause troubles such as design defects when processing a mold (lathe). This tendency is stronger as the cast bone and sipe blade intersect the split surface at an acute angle, but in the case of a two-piece mold in which the split surface must be set to a flat surface, it is unavoidable to cross the acute angle. It is often necessary.

That is, as shown in FIG. 24, in the case of a two-piece mold, the cast bone (or cast sipe blade) shape 9b intersects with the right angle with respect to the divided surfaces 8c of the upper and lower molds 8a and 8b. On the other hand (FIG. 24 (a)), when the green tire is set in the mold and the mold is closed, the bone (sipe) portion 9b is less likely to be damaged by the rubber material bitten by the divided surface portion. Damage to the bone (sipe) portion 9b when removing the tire after curing the green tire (after vulcanization) is also difficult to occur. On the other hand, in FIG. 24B, the bone (sipe) portion 9b intersects with the “acute angle” with respect to the dividing surface 8c, and bone damage is likely to occur. In FIG. 24, reference numeral 9a denotes a cast bone (rib).
"Outline of mold making method", published by the Association for Foundry Technology Dissemination, November 25, 1981, pp. 143-166

  However, the two-piece mold has a merit that the mold can be molded at a lower cost than the sectional mold because the mold dividing structure is simple and the mold cost and the maintenance cost are low.

  Thus, conventionally, there is no tire mold manufacturing method that satisfies both the mold manufacturing cost and the tire performance.

Therefore, as a result of various studies, the inventor cast a two-piece mold by matching the upper and lower molds.
(1) Merits in dimensional accuracy can be obtained by casting the upper and lower molds together.
(2) Although it is more difficult to deal with casting defects such as shrinkage cavities and pinholes, it is more difficult to deal with casting defects such as shrinkage cavities and pinholes by combining the upper and lower molds. ) Thanks to progress, it is possible to pre-examine high-accuracy casting methods, and the situation is almost overcome.
(3) If the upper and lower molds are combined and the ring casting is in the form of a “sectional mold”, the diameter shrinkage rate tends to continuously change from the lower mold to the upper mold, making it difficult to obtain the desired as-cast diameter. However, it is possible to obtain a casting having a target diameter between the upper and lower molds by adding an appropriate correction.
And the present invention has been completed.

  The present invention has been made in view of such circumstances, and a first object of the present invention is to provide a dimensional accuracy equivalent to that of a sectional mold manufacturing method in a two-piece mold type tire molding mold manufactured by casting. The object is to provide a technique that can be developed and can simultaneously cast upper and lower dies (for one set) by casting one ring.

  The second object is to provide a technology that can shape the split surface (PL surface) of the two-piece mold by “casting” (or “as-cast”) without using machining. Therefore, it is difficult to cope with the curved surface shape of the mold dividing surface.

  In order to achieve the above-described object, the invention of claim 1 is a method for manufacturing a tire molding die comprising two ring-shaped mold parts that are manufactured by a casting method and divided into two in the tire central axis direction. The two ring-shaped mold parts are integrated continuously via a general part having a thickness corresponding to the finishing machining between the opposing surfaces of the mold dividing surfaces that come into contact with each other when the parts are vertically aligned. The one-ring casting is cast and manufactured, and then the one-ring casting is manufactured and separated into upper and lower molds.

  Therefore, according to the first aspect of the present invention, a two-piece mold is cast in the form of an integral ring in a state where a finishing machining allowance is provided between (upper and lower molds) dividing surfaces, and the resulting ring casting is divided into upper and lower molds. Make two ring mold parts.

  The invention according to claim 2 is the method for manufacturing the tire molding die according to claim 1, wherein the one-ring casting corresponds to each die dividing surface of the two ring-shaped die parts. Each part is formed by casting a divided surface having a width of 10 mm or more and half or less the thickness of the one-ring casting from the design surface portion of the one-ring casting to the thickness direction of the back portion. When the one ring casting after casting is processed and separated into upper and lower molds, the mold splitting is performed by leaving each of the casting split surfaces as mold split surfaces of the two ring mold parts. The surface is formed by casting.

  For this reason, in the invention of claim 2, since the upper and lower mold dividing surfaces on the design surface side are formed by “casting”, the machining of this part becomes unnecessary, and thus design defects or the like due to the processing occur. It becomes difficult.

  In addition, since the divided surface on the design surface side at this time is formed with a width of 10 mm or more and a width of 1/2 or less of the thickness of one ring casting, it has sufficient durability and is cast. It is less likely to interfere with the “push-up” effect of the time.

The invention of claim 3 is the tire mold manufacturing method according to claim 2, wherein the mold division plane formed by out casting is substantially at right angles to the design surface projections It is characterized by having curved surface shapes that intersect.

  For this reason, in the invention of claim 3, since the design surface protrusion and the mold dividing surface intersect at a substantially right angle, the appearance of an acute angle crossing state can be reduced, and the design surface protrusion is lost accordingly. Is less likely to occur.

  The invention according to claim 4 is the method for manufacturing a tire molding die according to any one of claims 1 to 3, wherein the casting mold for the one-ring casting uses a top and bottom mold as a continuous body. The plurality of sectors divided in the circumferential direction are assembled in a ring shape.

  For this reason, in the invention of claim 4, it is possible to express high dimensional accuracy by avoiding joining the upper and lower molds at the stage of the mold and using the sector of the upper and lower integrated structure.

  As described above, according to the invention of claim 1, a two-piece mold type tire molding die manufactured by casting can exhibit dimensional accuracy similar to that of the sectional mold manufacturing method, and is cast by one ring. Since the upper and lower molds (for one set) can be cast at the same time, further cost merit can be achieved in comparison with the conventional two-piece mold manufacturing method by simplifying the process.

  Further, according to the invention of claim 2, since the upper and lower mold dividing surfaces on the design surface side are formed by “casting”, the machining of the dividing surface becomes unnecessary, so that the effect of the invention of claim 1 is achieved. In addition, design defects due to processing are less likely to occur, and a tire molding die with higher dimensional accuracy can be manufactured.

  In addition, since the upper and lower mold dividing surfaces on the design surface side are formed to have a width of 10 mm or more and 1/2 or less of the wall thickness of one ring casting, they are excellent in durability and the “push-up” at the time of casting. It can bring about a good casting operation without hindering the effect.

  Further, according to the invention of claim 3, since the design surface protrusion and the mold dividing surface intersect each other at a substantially right angle, it is possible to reduce the appearance of an acute angle crossing state. In addition to the above effects, the design surface protrusion is less likely to be lost, and a tire molding die with higher dimensional accuracy can be manufactured.

  According to the invention of claim 4, since the upper and lower molds are avoided from being joined at the mold stage, and the sector of the upper and lower integrated structure is used, the effect of the invention of any one of claims 1 to 3 is achieved. In addition, a tire molding die with higher dimensional accuracy can be manufactured.

  According to the invention of claim 5, since the tire molding die is composed of two ring-shaped die parts manufactured with high dimensional accuracy, a high level can be obtained by using the die. A tire with the uniformity of can be manufactured.

  Hereinafter, the present invention will be specifically described based on embodiments.

  1 and 2 show the steps of a manufacturing method I of a tire molding die as a first embodiment of the present invention.

  This manufacturing method I is a method of manufacturing a tire molding die 8 made of two ring-shaped die parts (upper die 8a and lower die 8b) that are manufactured by a casting method and divided into two in the tire central axis direction. The two ring-shaped mold parts are integrated with each other through a general portion 14 having a thickness corresponding to the finishing machining between the opposing surfaces of the mold dividing surfaces that are in contact with each other when the parts are vertically aligned. The one-ring casting 13 is cast and manufactured as a continuous one-ring casting 13, and the one-ring casting 13 after casting is processed and separated into upper and lower molds 8a and 8b.

  At this time, the casting mold 4 of the single ring casting 13 is preferably formed by assembling a plurality of sectors 3 divided in the circumferential direction into a ring shape with the upper and lower molds as a continuous body.

  Specifically, as shown in FIGS. 1 and 2, first, a finishing portion is expected for the central portion 1c corresponding to the portion where the divided surfaces of the upper and lower master models 1a and 1b are in contact with each other. The master model 1 is manufactured by processing in an integrated shape (FIG. 1A). In the master model 1, the upper mold 8 a and the lower mold 8 b are arranged on the upper and lower sides of the center portion 1 c in the positional relationship between the upper mold 8 a and the lower mold 8 b constituting the final-shaped tire molding mold 8, respectively. It is formed to be located. The master model 1 may be manufactured separately, and may be manufactured by vertically joining the lower master models 1a and 1b. The joining part at this time is shown by the broken line in the center part 1c.

  Next, the rubber mold 2 was inverted from the master model 1 using silicone rubber or the like (FIG. 1 (b)), and then the sector 3 (see FIG. 17 (d)) was used from the rubber mold 2 using gypsum or the like. In addition, the necessary number of pieces are reversed, dried, and cut at an angle (FIG. 1C). This step can be performed in the same manner as in the past. In FIG. 1B, reference numeral 10 denotes a backup layer that maintains the shape of the rubber mold 2.

  Next, the produced plurality of sectors 3 are assembled in a ring shape on the surface plate 11 to produce a casting mold 4 (see FIG. 17E) (FIG. 1D). After assembly, secondary drying is performed if necessary. After the assembly, the cavity in the center of the ring is filled with the backup layer 10. The platen 11 is provided with a vacuum exhaust hole 11 a at a location corresponding to the backup layer 10.

  Next, the casting mold 4 is surrounded by a casting frame 12, and a molten alloy 6 such as an aluminum alloy is filled between the casting mold 4 and the casting frame 12 for casting (FIG. 1 (e)). In FIG. 1 (e), the molten metal above the mold 4 is a feeder 6a. Reference numerals 8a and 8b indicate the positional relationship between the upper mold and the lower mold constituting the final-shaped tire molding mold 8. (Hereinafter, the same applies to FIGS. 1 (f) and (g) and FIGS. 2 (h), (i), and (j)).

  After the molten metal is solidified and cooled, the mold 4 is disintegrated and removed to obtain a one-ring casting 13 (FIG. 1 (f)). The one-ring casting 13 is integrally and continuously manufactured through a general portion 14 having a thickness corresponding to the finishing machining between the opposing surfaces of the upper and lower molds 8a and 8b.

  Next, the feeder 6a portion of the one-ring casting 13 is cut and removed, and the inner diameter is measured (FIG. 1 (g)). As a result of this measurement, if the inner diameter needs to be expanded or reduced, the outer peripheral portion 13c is subjected to intermediate processing into a shape commensurate with the correction.

  In the diameter expansion correction, for example, as shown in FIG. 2 (h), a force in the direction of the arrow is applied to each of the cams 16a, 16b, and 16c by pulling the wedge 15 in the direction of the arrow by hydraulic pressure. This is done using a cam expander that expands in diameter.

  Further, in the diameter reduction correction, for example, as shown in FIG. 2 (i), the restraint ring 18 is fitted on the outside of the one-ring casting 13, and the restraint ring 18 is heated by setting the whole in the heating furnace 17. The diameter of the one ring casting 13 can be reduced along the shape. At this time, the constraining ring 18 is formed using a material having a smaller coefficient of thermal expansion than the one-ring casting 13 and a higher yield strength. For example, when the material of the one ring casting 13 is an aluminum alloy, the material of the restraining ring 18 is various cast irons, steel materials, nickel alloy materials, and copper alloy materials. In FIG. 2I, reference numeral 19 denotes a heater, and reference numeral 20 denotes a fan.

  Thus, dimensional correction such as diameter expansion correction and diameter reduction correction is performed as necessary. Of course, this correction may be performed after the upper and lower molds are divided in the next step (FIG. 2 (j)). In order to minimize the generation of the step, it can be said that it is desirable to correct the diameter before the division.

  Next, as shown in FIG. 2 (j), the general portion 14 (see FIG. 1 (f)) having a thickness equivalent to the finishing machining is cut off by a lathe, saw blade cutting by a contour machine, etc., wire discharge The one ring casting 13 is separated into an upper mold ring casting 13a and a lower mold ring casting 13b.

  Next, as shown in FIGS. 2 (k) and 2 (l), the upper mold ring casting 13a (or the lower mold ring casting 13b) is processed by the processing machine 21 to form the tire molding die 8. The upper mold 8a and the lower mold 8b, which are two ring-shaped mold parts, are manufactured. The processing machine 21 is mainly composed of a cutting tool 22 and a rotating bed 23. The upper mold ring casting 13a (or the lower mold ring casting 13b) is fixed to the rotating bed 23 and rotated, and the casting 13a ( The outer peripheral part of the casting 13a (13b) is processed into a predetermined shape by applying the cutting blade of the cutting tool 22 to the side surface of 13b).

  As described above, in the manufacturing method I, a two-piece mold (upper and lower molds) is cast in the form of an integral ring in a state where a finishing allowance is provided between split surfaces, and the resulting ring casting is converted into an upper and lower mold after dimensional correction. This is a method of dividing and manufacturing a ring mold for two-piece molding (tire molding mold 8, upper and lower molds 8a, 8b).

And according to this manufacturing method I,
(1) The upper and lower molds can be obtained simultaneously by casting one ring.
(2) Since the upper and lower molds are cast simultaneously, the casting shrinkage variation between the upper and lower molds can be reduced.
(3) Since the upper and lower molds are cast together, the roundness tendency between the upper and lower molds is the same.
It is possible to give the advantage of “sectional mold”.

  That is, according to the first invention, in addition to the merit of the mold production cost and the mold maintenance cost of the two-piece mold, it is possible to give a dimensional accuracy characteristic similar to that of the sectional mold. It is possible to easily overcome the weaknesses of the two-piece mold, that is, the ease of occurrence of misalignment between the upper and lower molds and the ease of occurrence of the upper and lower mold radius differences.

  In a preferred embodiment, the upper and lower molds are avoided from being joined at the stage of the mold, and the one with the upper and lower structures (sector 3) is used so that high dimensional accuracy is expressed for the tire molding mold 8. It is intended. This is due to the following reason.

  In other words, as described in the process of FIG. 1A, it is explained that at the stage of the master model, it is possible to assemble and form the parts divided (separated) for the upper and lower molds. . This is because the joining accuracy of the model (core misalignment, step, etc. between the models for the upper and lower molds) is easy to manage and easy to maintain until the rubber mold is reversed.

  However, if the same thing is done with a mold (gypsum mold, ceramic mold), the joining accuracy between the upper and lower molds tends to deteriorate.

As shown in FIG.
(1) Joining the upper and lower dies 3a and 3b in the mold (sector 3) increases the number of joints and increases the probability of joining errors, and the mold is lower in strength than the master model 1. , Maintaining the bonded state is difficult,
(2) Since the mold (sector 3) undergoes a “drying” or “firing” step, deformation in this step is likely to occur, and when the upper and lower dies 3a and 3b are joined, deviation and gaps are likely to occur. thing,
(3) When the upper and lower molds 3a and 3b are joined in the mold (sector 3), thermal expansion due to heat input during casting (transformation shrinkage also occurs in the case of gypsum mold), molten metal pressure, decompression and suction to the mold. Deviation due to external force such as force is likely to occur, and due to this deviation, molten metal is inserted into the joint surface part, and `` casting burr '' is likely to occur, and the tire width dimension is easily changed accordingly,
This is because there is a reason to say.

  In addition, the ring-shaped mold 4 in the steps of FIGS. 1D and 1E is made of gypsum. When the gypsum mold 4 exceeds about 300.degree. In order to show the behavior, the slower the melt solidification, the greater the amount of transformation shrinkage, and there is a case where the mold 4 tends to shrink better (that is, the diameter becomes smaller). Although it is qualitative, as shown in FIG. 4, in the gravity casting method (FIG. 4A), the diameter shrinkage of the casting 13 tends to be larger on the upper die 8 a side than on the lower die 8 b side, In the low pressure casting method (FIG. 4B), the opposite tendency is shown.

  That is, when the ring casting 13 for a tire mold is cast by the gravity casting method (FIG. 4A), if the gypsum mold 4 is assembled to the same diameter with the upper and lower molds, the ring casting 13 has the upper mold 8a side. Since it takes a long time to solidify the molten metal, the inner diameter tends to be smaller on the upper mold 8a side. When casting the ring casting 13 for a tire mold by the low pressure casting method (FIG. 4B), when the gypsum mold 4 is assembled to the same diameter with the upper and lower molds, the lower mold 8b side of the ring casting 13 is the molten metal. Since it takes a long time to solidify, the inner diameter tends to be smaller on the lower mold 8b side.

  When the gypsum mold 4 is used in this way, the diameter contraction rate of the ring casting 13 tends to continuously change from the lower mold 8b side to the upper mold 8a side, but it is difficult to obtain the desired cast diameter. By applying an appropriate correction, it is possible to obtain a casting 13 having a target diameter between the upper and lower molds.

  As the correction method at this time, as shown in FIG. 5 (gravity casting method) and FIG. 6 (low pressure casting method), a shape in which the difference between the upper and lower mold shrinkage rates is corrected is set at the time of the master model 1 ( Model correction method, Fig. 5 (a) and Fig. 6 (a)), or at the stage of gypsum mold, the outer periphery is processed by tilting forward and backward, and the shape is corrected by correcting the difference between the upper and lower mold shrinkage (mold) The sector 3 as the gypsum mold shape is corrected by either the correction method, either FIG. 5 (b) or FIG. 6 (b)), and this is assembled into a ring shape (ring-shaped mold 4) and cast. By doing so, it is possible to obtain a casting 13 having a target diameter between the upper and lower molds (FIGS. 5C and 6C).

  In addition, when a ceramic mold material is used instead of a plaster material, the ceramic mold material does not show a transformation shrinkage behavior even when heat is applied during aluminum alloy casting. Differences are unlikely to occur.

  FIG. 7 shows the steps of a method II for manufacturing a tire molding die as a second embodiment of the present invention. This manufacturing method II is different in that the mold dividing surface (PL surface) is not formed by machining such as lathe processing but “casting”, and the other configuration is the manufacturing method described above. The configuration is the same as I.

  That is, the one-ring casting 13 in the manufacturing method II is formed from the design surface portion 13d of the one-ring casting 13 to each part corresponding to each die dividing surface of the two ring-shaped mold parts (upper die 8a, lower die 8b). A casting divided surface 24 having a width of 10 mm or more and a width of 1/2 or less of the thickness T of the one ring casting 13 is formed by casting in the thickness direction of the back surface portion 13e. When the ring casting 13 is processed and separated into the upper and lower molds 8a and 8b, each of the casting divided surfaces 24 is left as the mold dividing surfaces of the two ring-shaped mold parts (upper mold 8a and lower mold 8b). Thus, the mold dividing surface is formed by casting.

  Specifically, as shown in FIG. 7, on the master model 1, the mold dividing surface shape can be “cast out” on a part (or the entire surface) of the finishing machining portion between the upper and lower dies 8 a and 8 b. The shape (projecting part 25) is projected (FIG. 7A).

  Next, similarly to the manufacturing method I described above, the required number of sectors 3 are reversed by using gypsum or the like from the rubber mold, and the plurality of sectors 3 are assembled to manufacture the ring-shaped mold 4 (FIG. 7 ( b)).

  Next, in the same manner as in the manufacturing method I described above, the ring mold 4 is surrounded by a casting frame and cast, and after the molten metal is solidified and cooled, the mold is released to produce the ring casting 13 (FIG. 7C). The ring casting 13 is formed with a casting divided surface 24 having a width D corresponding to the protruding amount of the overhang portion 25 formed on the master model 1. At this time, the casting divided surface 24 is formed so that the width D thereof is 10 ≦ D ≦ T / 2 (unit mm), where T is the thickness of the casting 13 in the absence of the overhanging portion 25. Is done. This is because if the width D is less than 10 mm, the durability as the dividing surface 24 becomes poor, and when the width D exceeds T / 2, in the vicinity of the corresponding portion of the overhang 25 at the time of casting. This is because the “hot water” effect is difficult to work, and “shrinkage nest” defects are likely to appear.

  Next, similarly to the manufacturing method I described above, after correcting the diameter as necessary, the ring casting 13 is divided into an upper mold ring casting 13a and a lower mold ring casting 13b (FIG. 7D). ). At this time, the upper and lower parts are divided with care so as not to damage the as-cast division surface.

  Furthermore, after the division, the outer ring processing of the lower mold ring castings 13a and 13b is performed (FIG. 6 (e)), and the lower molds 8a and 8b (design surface mold 8) are obtained on the two-piece mold (FIG. 7 ( f)). The upper and lower mold dividing surfaces on the design surface side are cast-out divided surfaces 24 formed by “casting” by the dimension D in FIG. 7C.

  As described above, according to the manufacturing method II, it is possible to form part (or the entire surface) of the upper and lower mold dividing surfaces of the two-piece mold for molding a tire by “casting”. As a result, machining of at least the mold dividing surface portion (casting divided surface 24) on the design surface side of the upper and lower molds is unnecessary, and the processing man-hours can be reduced, and at the same time, design defects due to processing of the corresponding portions, etc. There is an advantage that it is possible to avoid the occurrence of problems.

  Moreover, in the manufacturing method II, the overhang | projection part 25 in Fig.7 (a) is formed as follows as needed.

  As shown in FIG. 8, the overhang portion 25 is a design surface portion of the model 1 in a state in which the overhang portion 25 for mold parting surface casting is provided in advance on the master model 1 (FIG. 8A). If the “pin angle” corner shape 26a is required for the design (groove shape) 26 of the portion related to the dividing surface 25a (FIG. 8B), the tool of the processing tool 27 is actually processed after processing. There is a problem that the R shape 26b has a half diameter (FIG. 8C). In FIG. 8A, the master model 1 shows only the upper mold side portion.

  Therefore, the overhang portion 25 is formed by the “partial retrofitting method” (FIG. 9A) or the “total separation joining method” (FIG. 9B) shown in FIG. 9 in order to solve the above problems. Is done.

  That is, in the “partial retrofitting method”, as shown in FIG. 9A, the master model 1 has a relief recess 1 d formed below the projection on which the design 26 is formed. The master model 1 is formed by applying the design 26 to the projecting portion and then retrofitting an overhanging portion 25 in which only a main portion is formed in a piece shape to the escape recess 1d. In the “partial retrofitting method”, the master model 1 is integrally formed with an upper mold and a lower mold from the beginning.

  In addition, as shown in FIG. 8 (b), the “total separation joining method” is performed by separately forming the master model 1 into an upper master model 1a and a lower master model (not shown), and then for each model. A design 26 is applied to a predetermined convex portion using a processing tool 27, and then the upper master model 1a is formed through an overhang portion 25 having the same size as the central portion 1c of the master model 1 and integrally formed. And the lower master model are combined to form the master model 1.

  In this case, the “partial retrofitting method” is more preferable in terms of dimensional accuracy because the master model 1 of the upper and lower mold design surface portions can be processed with an integral structure, but the “total separation joining method” is also preferable. There is no problem if sufficient attention is paid to the synchronization of the concentricity and roundness tendency between the upper and lower molds when joining the overhang shaped part and the master model for the upper and lower molds.

  In addition, in order to prevent the defect | deletion of the corresponding cast bone, the both ends of the cast bone applied to the upper and lower mold dividing surfaces of the two-piece mold may be intentionally R-shaped. It is not necessary to use “pin angle”.

  FIG. 10 shows a part of the process of the manufacturing method III of the tire molding die as the third embodiment of the present invention. This manufacturing method III is the same as the manufacturing method II described above except that the mold dividing surface formed by casting has a curved shape.

  That is, the mold dividing surface 28 (see FIG. 10B) formed by casting in the manufacturing method III is a curved surface shape that intersects with a design surface protrusion such as a casting bone or a cast-in sipe blade at a substantially right angle. It is formed.

  Specifically, as shown in FIG. 10A, the master model 1 is formed by the “total separation joining method” described above using the overhang portion 25. In FIG. 10A, only the upper mold 1 a side is shown, but the shape of the upper and lower mold dividing surfaces 25 a of the master model 1 is set to a curved surface that is as orthogonal as possible to the design (groove shape) 26.

  At this time, the “total separation joining method” is adopted in the case where the curved surface shape of the dividing surface 25a is defined by rotation including the vertical movement of the straight line about the radius center of the master model 1 (see FIG. 10 (a)), when a “pin angle” (see “pin angle” corner shape 26a in FIG. 8B) is to be applied to the corner of the groove 26 on the dividing surface 25a. This is because it becomes difficult to deal with the overhanging portion 25 of the master model 1a by the “partial retrofitting method” described above (because the overhanging portion to be retrofitted has an undercut shape in the model radial direction). Therefore, if the curved surface shape of the dividing surface 25a is defined by “parallel movement” including vertical movement of the straight line, it is possible to deal with the “partial retrofitting method”.

  In the manufacturing method III, as in the manufacturing method II described above, a ring casting is obtained, and after the ring casting is separated into the upper and lower mold ring castings, predetermined outer periphery processing is performed to perform the upper and lower molds 8a and 8b (tire molding metal The mold 8) can be completed.

  According to this manufacturing method III, as shown in FIG. 10B, the upper and lower mold dividing surfaces 28 formed by “casting” on the design surface side are curved surfaces, and the lathe-finished rear surface side is a flat surface 28a. A tire molding die 8 having a surface shape can be manufactured.

  As shown in FIG. 11A, the tire molding die 8 intersects the upper and lower mold dividing surfaces 28 with a shape close to “orthogonal” with a cast bone (sipe) 9 b applied to the dividing surfaces 28. Since it formed in the curved surface, the defect | deletion of the corresponding cast-out bone 9b at the time of tire shaping | molding can be made hard to occur.

   Incidentally, when the “plane” division of the conventional method is performed, when the cast bone 9b intersects the split surface 29 at an “acute angle” as shown in FIG. 11 (b), the cast bone side surface 9c on the acute corner side is broken. It becomes easy to do. In FIGS. 11A and 11B, reference numeral 9a denotes a cast bone (rib).

  Further, in the manufactured tire molding die 8, since the dividing surface 28 becomes a curved surface, the dividing surface 28 itself acts as an upper and lower mold positioning mechanism (an imprint or dowel), and the upper and lower molds 8 a and 8 b A ripple effect that reduces the possibility of misalignment can also be achieved.

  As described above, according to the manufacturing method III, the mold dividing surface 28 formed by casting can be easily formed with the curved surface shape having the above-described excellent function.

  Incidentally, when the curved surface shape of the mold dividing surface 28 is formed by machining as in the conventional case, since a general-purpose lathe cannot be used, an NC processing machine is used, which causes an increase in equipment costs. ing. This is the same when repairing the corresponding split surface, and NC machining is essential after welding.

  Next, the dimensional accuracy of the tire molding die 8 manufactured by the manufacturing methods I, II, and III described above will be described.

  FIG. 12 shows the basic outer shape of the upper die 8a of the design surface mold manufactured in Examples I and II and Comparative Examples I and II (design surface design is omitted, tire size 205 / 60R13 two-piece mold type tire (Die) and dimensions (unit: mm) of each part. FIG. 12 shows only the upper die 8a of the design surface mold, but the lower die also has the same basic outer peripheral shape and dimensions.

  Other mold conditions are as follows.

Basic pitch types: 3 types of S, M, and L Number of pitches: S pitch 9 pieces, M pitch 9 pieces, L pitch 6 pieces No sipe blade casting and basic manufacturing conditions for tire molds (Example I, II and common conditions for Comparative Examples I and II) are as shown below.

Basic mold manufacturing method: Plaster casting method Set shrinkage: 11-15 / 1000 (varies depending on the part)
Gypsum mold material: USG Hydro Palm Foam Gypsum (mixed with 70% by weight of water mixture and 60% foaming increase)
Casting alloy: AC4C alloy (7.0% Si, 1% Cu, 0.5% Fe, 0.4% Mg, remaining Al)
Casting method: Gravity casting (casting method)
Example I:
As shown in FIG. 13, the finishing machining allowance is set at the central portion 1c on the master model 1, and the master model 1 in which the upper and lower molds 1a and 1b are integrated is manufactured. Through the steps of manufacturing method I, a two-piece mold (two split molds (Example I), upper and lower molds 8a and 8b) was manufactured. The casting (one-ring casting 13 in FIG. 1 (g)) was subjected to diameter expansion correction by an expander by 0.3 to 0.4 mm in a state of being integrated vertically, and then subjected to upper and lower mold division and outer periphery processing.

実施例ＩＩ：
図１４に示すように、上、下型分割面２８、２８を、図１４（ｂ）、（ｃ）に示すような曲面とすることを狙って、図１４（ａ）のようなマスターモデル１を製作し、以降は製造方法ＩＩおよびＩＩＩと同様な工程を経て、２ピースモールド（２つ割り金型８（実施例ＩＩ）、上、下型８ａ、８ｂ）を製作した。鋳物（図１（ｇ）の１リング鋳物１３）は、上下一体の状態で、エキスパンダーにより０．３〜０．４ｍｍ程直径拡張矯正を施した後、上、下型８ａ、８ｂに分離した。 Table 3 shows the dimensional accuracy of the lower molds 8a and 8b (Example I) on the two-piece mold thus obtained.

Example II:
As shown in FIG. 14, the master model 1 as shown in FIG. 14 (a) is aimed at making the upper and lower mold dividing surfaces 28, 28 into curved surfaces as shown in FIGS. 14 (b) and 14 (c). After that, through the same process as the manufacturing methods II and III, a two-piece mold (two split mold 8 (Example II), upper and lower molds 8a and 8b) was manufactured. The casting (one-ring casting 13 in FIG. 1 (g)) was subjected to diameter expansion correction by an expander by 0.3 to 0.4 mm in an integrated state, and then separated into upper and lower molds 8a and 8b.

  As shown in FIG. 14A, the master model 1 is produced by individually manufacturing the upper mold master model 1a, the lower mold master model 1b, and the central portion 1c, and then using a coupling means such as a wedge 30. Produced by

  Further, as shown in FIG. 14B, the dividing surface 28 is set to a sine wave (wave shape) curved surface for one cycle with an amplitude of 15 mm per pitch. It is formed to have a corrugated curved surface.

  Next, when the castings separated into the upper and lower molds 8a and 8b were temporarily combined with the upper and lower molds, a gap of about 0.10 mm at the maximum was generated in the as-cast split surface 28, so electric discharge machining using the upper and lower molds as electrodes. After performing the sliding (discharge sliding) by making the gap almost zero, it was processed into a predetermined outer peripheral shape.

比較例Ｉ：
図１５に示すように、上下型を分割した形態のマスターモデル１００を製作し、従来製法（図１６参照）のように、上下型を別々に鋳造することで２ピースモールド（２つ割り金型（比較例Ｉ）、上、下型）を製作した。図１５は、上型８ａのみを示すが、その下型も同様の基本外周形状および寸法を有している。鋳物（図１６（ｅ）のリング状の鋳型４、参照）は、上下別々の状態で、エキスパンダーにより０．３〜０．４ｍｍ程直径拡張矯正を施した。 Table 4 shows the dimensional accuracy of the lower molds 8a and 8b (Example II) on the two-piece mold thus obtained.

Comparative Example I:
As shown in FIG. 15, a master model 100 in which the upper and lower molds are divided is manufactured, and the upper and lower molds are separately cast as in the conventional manufacturing method (see FIG. 16) to thereby form a two-piece mold (two split molds). (Comparative Example I), upper and lower molds) were manufactured. FIG. 15 shows only the upper die 8a, but the lower die also has the same basic outer peripheral shape and dimensions. The casting (see the ring-shaped mold 4 in FIG. 16E) was subjected to diameter expansion correction by an expander by 0.3 to 0.4 mm in separate states.

比較例ＩＩ：
図１５に示すように、上下型を分割した形態のマスターモデル１００を製作し、上下型用の石膏鋳型を別々に製作しておき、リング状に組立てる時点（図１６（ｅ）あるいは図１７（ｅ）の工程に相当する）で、上下型用の各石膏鋳型を上下に重ねて組立てることで一体化し、以降は製造方法Ｉと同様な工程を経て、２ピースモールド（２つ割り金型（比較例ＩＩ）、上下型）を製作した。鋳物（図１（ｇ）の１リング鋳物１３参照）は、上下一体の状態で、エキスパンダーにより０．３〜０．４ｍｍ程直径拡張矯正を施した後、上下型分割，外周加工を施す。 Table 5 shows the dimensional accuracy of the two-piece mold upper and lower molds (Comparative Example I) thus obtained.

Comparative Example II:
As shown in FIG. 15, the master model 100 in which the upper and lower molds are divided is manufactured, and the gypsum molds for the upper and lower molds are separately manufactured and assembled into a ring shape (FIG. 16 (e) or FIG. e) corresponding to the process of e), and by integrating the gypsum molds for the upper and lower molds by stacking them up and down, the two-piece mold (two-part mold ( Comparative Example II), upper and lower molds) were produced. The casting (see 1-ring casting 13 in FIG. 1 (g)) is vertically integrated and subjected to diameter expansion correction by an expander by about 0.3 to 0.4 mm, and then is subjected to upper and lower mold division and outer periphery processing.

表３と表５とを比較することにより、実施例Ｉは、比較例Ｉに比べて高寸法精度を備えたタイヤ成形用金型であることが理解できる。 Table 6 shows the dimensional accuracy of the two-piece mold upper and lower molds (Comparative Example II) thus obtained.

By comparing Table 3 and Table 5, it can be understood that Example I is a tire molding die having higher dimensional accuracy than Comparative Example I.

  As a result, the manufacturing method I is capable of expressing dimensional accuracy equivalent to the sectional mold manufacturing method while being a two-piece mold type tire molding die manufactured by casting. 1 set) can be cast at the same time, so that further cost merit can be achieved as the process is simplified.

  Further, by comparing Table 3 and Table 6, it can be understood that Example I is a tire molding die having higher dimensional accuracy than Comparative Example II.

  As a result, the manufacturing method I employs a method of forming a casting mold by assembling the sector 3 with the lower gypsum mold as a continuous body into a ring shape (see FIG. 1D). In addition, after molding the lower gypsum molds 3a and 3b (see FIG. 3), the tire molding with higher dimensional accuracy than the manufacturing method of Comparative Example II in which a casting mold is formed by assembling in a ring shape. It can be understood that a metal mold can be manufactured.

  Further, by comparing Table 4 with Tables 5 and 6, it can be understood that Example II is a tire molding die having higher dimensional accuracy than Comparative Examples II and III.

  Thereby, it can be understood that the manufacturing method II can easily cope with the curved surface of the mold dividing surface while maintaining the high dimensional accuracy of the mold.

It is a conceptual diagram which shows the process of the manufacturing method I of the tire shaping die as 1st Embodiment of this invention. It is a conceptual diagram which shows the process of the continuation of the manufacturing method I of FIG. It is a conceptual diagram explaining the dimensional defect which generate | occur | produces when manufacturing the gypsum mold (sector) in the manufacturing method I of FIG. FIGS. 2A and 2B are conceptual diagrams for explaining a dimensional defect caused by a difference in casting method in the casting process of the manufacturing method I in FIG. 1, where FIG. 1A shows the case of gravity casting, and FIG. 1B shows the case of low pressure casting. FIG. 5 is a conceptual diagram illustrating a method for correcting a dimensional defect that occurs in the case of gravity casting in FIG. 4, where (a) is a model correction method, (b) is a mold correction method, (c) is a ring-shaped mold after correction, and Each casting cast with the mold is shown. FIG. 5 is a conceptual diagram illustrating a method for correcting a dimensional defect that occurs in the case of low-pressure casting in FIG. 4, where (a) is a model correction method, (b) is a mold correction method, (c) is a ring-shaped mold after correction, and Each casting cast with the mold is shown. It is a conceptual diagram which shows the process of the manufacturing method II of the tire shaping die as 2nd Embodiment of this invention. FIG. 9 is a conceptual diagram illustrating the relationship between the overhanging part for the upper and lower mold parting surface casting shape on the master model and the processing of the design (groove shape) part on the master model in the manufacturing method II of FIG. (B) is a principal part front view explaining a target shape, (c) is a principal part front view explaining the shape which can actually be processed. FIG. 7 is a conceptual diagram only on the upper mold side for explaining a method of imparting a target shape to the design (groove shape) portion in relation to the overhang portion of FIG. 7 and the processing of the design (groove shape) portion, (a) is a portion A retrofitting method is shown, and (b) shows a whole separation joining method. It is a conceptual diagram which shows a part of process of the manufacturing method III of the tire shaping die as 3rd Embodiment of this invention, (a) shows the process of forming an overhang | projection part in a master model, (b) is The tire mold as the final product is shown. (A) has shown the relationship between the up-and-down type | mold division | segmentation surface which has the curved-surface shape formed by the manufacturing method III of FIG. 10, and a casting bone, (b) The relationship with the cast bone is shown. It is sectional drawing which shows the basic outer periphery shape of the upper mold | type of the design surface metal mold | die manufactured through all the Examples and all the comparative examples, and the dimension (unit mm) of each site | part. It is sectional drawing which shows the outer periphery shape of the master model of Example I, and the dimension (unit mm) of each site | part. It is a conceptual diagram in Example II, (a) is sectional drawing which shows the outer periphery shape of a master model, and the dimension (unit mm) of each site | part, (b) is a principal part front view of the metal mold | die for tire molding, (c). FIG. 2 is a cross-sectional view and a perspective view of a tire mold. It is sectional drawing which shows the outer periphery shape of the master model of the comparative examples I and II, and the dimension (unit mm) of each site | part. It is a conceptual diagram which shows the process of the manufacturing method of the conventional 2 piece mold type tire shaping die. It is a conceptual diagram which shows the process of the manufacturing method of the conventional mold for tire molding of a sectional mold type. It is a conceptual diagram of a tire uniformity check test. FIG. 19 is a conceptual diagram for explaining mold accuracy guarantee items obtained in the uniformity confirmation test of FIG. 18, where (a) is a roundness characteristic (RUN−OUT = Rmax), and (b) is a misalignment characteristic I (RRO = 2Re). ), (C) are misalignment characteristics II (RRO difference = 2Le), (d) are upper and lower die diameter difference characteristics (diameter difference = D1-D2), and (e) buttress part protrusion characteristics (Ta = Max value), respectively. Show. It is a conceptual diagram which shows the adjustment process by the end surface surplus setting method of the conventional sectional mold, (a) Roundness before adjustment processing, (b) Adjustment processing step, (c) Roundness after adjustment processing Respectively. It is a conceptual diagram which shows the upper-lower mold misalignment characteristic between the molds for tire molding of the different types manufactured by the conventional gypsum casting method, (a) shows 2 piece mold type, (b) shows sectional mold type, respectively. It is a conceptual diagram which shows the upper-lower mold diameter difference characteristic between the molds for a different type of tire manufacture manufactured by the conventional gypsum casting method, (a) shows a 2 piece mold type, (b) shows a sectional mold type, respectively. It is a conceptual diagram showing the roundness characteristics between the upper and lower molds of different types of tire molding molds manufactured by the conventional gypsum casting method, (a) is a two-piece mold type, (b) is a sectional mold type Each is shown. It is a principal part conceptual diagram explaining the difference of the intersection state of the division surface and cast-out bone in the two-piece mold type tire molding die manufactured by the conventional gypsum casting method, (a) intersects at right angles. The state (b) shows a state intersecting at an acute angle.

Explanation of symbols

3 Sector 3a Upper type (sector)
3b Lower mold (sector's)
4 Ring mold (casting mold)
8 Tire mold 8a Upper mold (ring mold parts)
8b Lower mold (ring-shaped mold parts)
8c Dividing surface (die dividing surface)
9a Casting bone (design surface protrusion)
13 Ring casting (1 ring casting)
13d Design surface (1 ring casting)
13e Rear part (one ring casting)
14 General part 24 Mold division surface (Casting division surface)
28 Mold division surface (curved surface)
D Width (for split casting surface)
T Thickness (one ring casting)

Claims (4)

In a manufacturing method of a tire molding die comprising two ring-shaped mold parts that are manufactured by a casting method and divided into two in the tire central axis direction,
The two ring-shaped mold parts are integrated continuously via a general part having a thickness corresponding to the finishing machining between the opposing surfaces of the mold dividing surfaces that come into contact with each other when the parts are vertically aligned. A method for producing a mold for molding a tire, which is manufactured by casting and manufacturing as a single ring casting, and then processing and separating the one ring casting into upper and lower molds. A method for manufacturing a tire molding die according to claim 1,
The one-ring casting is 10 mm or more from the design surface portion of the one-ring casting to the thickness direction of the back portion at each portion corresponding to each mold dividing surface of the two ring-shaped mold parts. Each of the casting divided surfaces is formed by casting and separating the one-ring casting after casting into upper and lower molds. Is left as each mold dividing surface of the two ring-shaped mold parts, so that the mold dividing surface is formed by casting. A method for manufacturing a tire molding die according to claim 2,
Is the mold division plane formed by the out cast, the tire mold manufacturing method, characterized by being formed with a curved surface intersecting substantially at right angles with respect to the design surface projections. It is a manufacturing method of the metal mold for tire fabrication given in any 1 paragraph of Claims 1-3,
The casting mold for one ring casting is formed by assembling a plurality of sectors divided in the circumferential direction into a ring shape with the upper and lower molds as a continuous body, and manufacturing a mold for tire molding Method.

Images