JP2007015152A - Manufacturing method of piece assembling type tire mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a piece mold assembling type tire mold capable of casting and forming the tire mold in a state that a predetermined gap shape is imparted without machining the mutual fitting surfaces of piece castings. <P>SOLUTION: A design surface original mold, in which a design surface shape of one pitch unit and a plurality of side surface-shaped grooves of both ends of the design surface shape are carved, and a side surface original mold are manufactured. Respective rubber molds are reversely manufactured from these original molds and a necessary number of design surface casts and side surface casts are manufactured from the rubber molds by casting reversal. After the casts are baked/dried, the design surface casts are assembled in a ring form and the side surface casts corresponding to the design surface casts are fitted in and fixed to the groove parts of the design surface casts without forming a gap. The outer peripheries of them are surrounded by a casting frame and a molten metal is cast in the casting frame to cast and manufacture a ring casting wherein piece molds are connected in a ring form. The ring casting is dimensionally corrected and its outer periphery is processed by a lathe. After a necessary number of piece mold shapes are obtained, the piece molds are assembled in a holder. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is configured by assembling minute divided pieces like a jigsaw puzzle among molds used for tire molding, and the gaps (slits) between these pieces are closed by a mold shape. The present invention relates to a method for producing a non-spy tire mold (supure tire mold) of a type used as air escape in space. More specifically, the manufacturing cost when manufacturing a piece mold by casting + machining is minimized, and the design surface of the piece mold and the fitting surface portion between the piece molds are formed by casting, and machining is basic. In particular, it relates to technology that can be handled only by lathe processing.

  Tire molds can be divided into two parts in the width direction (upper and lower molds) and sectional molds (upper and lower ones) divided into about 7 to 13 in the circumferential direction. There are two main types. The most widely adopted method for casting tire molds is the use of a plaster casting method or ceramic mold that uses a collapsible mold such as gypsum to obtain aluminum alloy castings, iron and steel castings by low pressure casting or gravity casting. However, there is also a “die casting method” in which an aluminum alloy casting, iron, or steel casting is obtained by pressure casting using a non-collapseable mold such as steel.

  Since the gypsum casting method allows mold assembly and shape correction at the gypsum mold stage, there is an advantage in that a seamless “integrated casting” at the final shape level of the tire mold can be manufactured with high dimensional accuracy. In the case of the gypsum casting method, 2 rings with 2P mold and 1 ring with sectional mold can complete the casting of one set of molds, whereas the die casting method can be divided into many times (usually 50 to 200 times). If it is not cast, the casting for one set is not finished. For this reason, when considering the dimensional accuracy as a ring casting, it can be said that the dimensional variation of each part in one ring is small for the gypsum cast product, but the die cast product is affected by the variation of the number of castings. May appear. In addition, the die-casting method cannot provide an “undercut shape”, whereas the gypsum casting method is a collapsible mold, so it can be applied to the undercut shape with a high degree of freedom.

  On the other hand, considering from the solidification form of the casting, in the gypsum casting method, since the gypsum mold is a “heat insulating material”, the solidification of the molten metal occurs from the back side of the casting toward the design surface side. For this reason, there is a demerit that it is easy to generate “casting defects” on the important design surface side, whereas the die casting method causes solidification from the design surface side, so this problem is difficult to occur. Has the merit. For the same reason, the die-cast product also has an advantage that the casting strength characteristic becomes higher.

  In terms of casting production costs, it will be a comparison of "mold" production costs. When manufacturing several thousand or more identical castings, the die-cast method may be cost-effective, but such a situation is unlikely to occur with tire mold specifications. Therefore, it can be said that the casting production cost is cheaper in the gypsum casting method having a lower mold production cost. (The gypsum casting method can produce castings that are closer to the finished form, and the post-processing costs are lower.) In short, it requires a high level of skill to deal with casting defects. Gypsum casting is highly cost-effective and can handle any required shape with a high degree of freedom. Casting with good quality can be made relatively easily, but the die-casting method has low cost merit.

  The tire is formed by pressing an unvulcanized green tire against a tire mold and heat-curing the tire. For this reason, in a portion where a “closed space” is formed by contact between the tire mold design surface and the green tire, a deficiency in rubber filling in the tire is caused by residual air. As a countermeasure, various “air vent” functions are given to the tire mold.

There are three general venting mechanisms currently employed: vent holes, slit vents, and on-off valves.
The vent hole is for discharging air blocked between the mold and the rubber at the time of tire molding (compression molding) from a small hole (vent hole) opened in the mold body. For this reason, rubber whiskers occur in the corresponding parts, which is a demerit that the appearance characteristics and initial performance of the tire product are impaired, but the manufacturing cost of the mold is low, and cleaning when using the mold There is also a merit that it is easy to handle.

    Since the slit vent discharges the closed air from the gap when the small pieces of the mold are assembled, no spew is generated, and a burr-like rubber bulge is generated instead. This has excellent appearance characteristics as a tire and excellent initial performance, but has the demerits that the mold production cost is high and that it is difficult to perform cleaning when using the mold.

  The open / close valve is an open / close valve provided in the vent hole. An open / close valve mechanism is added to the vent hole opened in the mold to allow air to escape but not to allow rubber material to enter. It is. It can be said that it is a technology that overcomes the problems of the previous vent holes and slit vents, but it is a new technology that has not yet spread widely.

  Since the present invention relates to a slit vent type tire molding die, this technique will be described in detail. Various patents have been filed for slit vent type tire mold manufacturing methods. These are roughly divided into the following four types.

  The first is a laminated material machining method. This method is described in Patent Document 1 (Japanese Patent Laid-Open No. 2-295706). As shown in FIG. 1, after nesting in an appropriate part of the base material, the design surface is excavated by machining. Thus, a “slit” structure formed between “base material and nesting” is created in each part of the tire mold, and this is used as an air vent part. There is Patent Document 2 (Japanese Patent Laid-Open No. 2001-150441) as a similar patent, in which the nesting shown in the left figure is formed by “casting” by die casting as shown in FIG. Since the design surface is manufactured by machining, there is a weak point that it cannot handle complicated designs.

  The second is a “casting” method by die casting. This type of method is described in Patent Document 3 (Japanese Patent Laid-Open No. 2001-150455) and the like. As shown in Fig. 3, basically, a part of the base material (matrix phase mold or piece mold) made of aluminum alloy or iron-based alloy or the entire adjacent piece is made of aluminum alloy by die casting method. "Casting". The part that has been cast and solidified and cooled and contracted is used as a “slit”, making it an air vent mechanism for tire molds.

However, this method has the following three problems.
(1) Since the slit width dimension is determined by the amount of solidification and cooling shrinkage of the cast joint, it is difficult to strictly control the slit width dimension. (It can only be controlled by the width dimension on the casting side.)
(2) Basically, “steps” occur on the casting side and the casting side. (Occurs in a form similar to the part indicated by the horizontally long ellipse in the lower right of FIG. 3.)
(3) When curved joints are used instead of flat castings (see the lower side of Fig. 3), "unevenness" is generated at the site where the slits are formed. (This phenomenon is also caused by the fact that the shrinkage rate in the XYZ axis direction on the casting side changes.)

  The third is a method of “casting” different metal pieces by die casting. This method is described in Patent Document 4 (Japanese Patent Laid-Open No. 10-24423). As shown in FIG. 4, a steel material having a tire mold design surface shape (having a smaller thermal expansion coefficient than an aluminum alloy). The gaps created between the steel piece and the aluminum mold due to the difference in thermal expansion at the temperature (150 to 200 ° C) when the mold is used are defined as “slits”. It is used as a tire mold air vent mechanism. However, this method also has a weak point that it is difficult to control the slit width dimension to an intended value because the slit width dimension is determined by the difference in thermal expansion coefficient.

  The fourth is a “partition plate” divided piece casting method by a plaster casting method. This method is described in Patent Document 5 (Japanese Patent Laid-Open No. 2004-42505). As shown in FIG. 5, a ring-shaped casting is cast with a partition plate between gypsum molds. This is a method in which a slit corresponding to the thickness of the partition plate is formed between the piece castings when the piece castings obtained by the division are assembled in a ring in the holder. This method overcomes the above-mentioned three types of weaknesses, enables the production of piece molds with a small number of castings, and also allows the gap between pieces to be brought to the target dimensions. Although it can be said that it is a good method for aligning molds, even if you want to cast only a few pieces for mold repair, you must basically perform casting equivalent to one ring and follow up. It has a drawback that it is difficult to maintain a high-precision fit between the piece mold manufactured in step 1 and the piece mold that has already been completed.

In Patent Document 6 (Japanese Patent Laid-Open No. 2005-161575), as shown in FIG. 40, a mold having a design surface and a plurality of pieces of finishing machining surrounding the design surface is prepared, and the mold is formed on a surface plate. There is disclosed a tire mold manufacturing method in which a piece casting obtained by placing a die in a die and casting it into a square die and cutting it into pieces is assembled in a ring shape. It is also possible to manufacture the piece design surface and the piece side surface by casting by such a method. However, in this method, it is necessary to reassemble the finished piece casting into a ring shape, crush the mating surface and correct it, hold each piece casting on the surface plate again, and lathe the back and top and bottom surfaces. As a result, the production man-hours could not be reduced to the limit.
As described above, there are merits and demerits in the current production method of the piece assembly type tire mold, and the perfect production method has not been established.
JP-A-2-295706 Japanese Patent Laid-Open No. 2001-150441 Japanese Patent Laid-Open No. 2001-150455 Japanese Patent Laid-Open No. 10-24423 JP 2004-42505 A JP 2005-161575 A

  The present invention has been completed under such circumstances, and its purpose is to use a casting method using a collapsible mold material such as a gypsum casting method or a ceramic casting method, and a piece casting for a tire mold. In addition to providing a technology that enables efficient production of tires, a piece mold assembly type tire molding die that can be cast and formed with a predetermined gap shape without machining the mating surfaces between piece castings. It is to provide a mold manufacturing method.

In order to solve the above-mentioned problems, the invention of claim 1 is directed to a method of manufacturing a tire molding die of a piece die assembling method.
Design surface prototype corresponding to one piece mold and groove shape corresponding to the split surface of the piece mold at both ends in the circumferential direction are alternately engraved for multiple pieces on the same prototype. A piece mold that can be fitted into a groove shape that has been created and dug, and the height dimension protruding from the design surface mold after fitting is larger than the radial thickness dimension of the piece mold Separately make a prototype for the side with a surface shape corresponding to both circumferential end faces of
From these design surface prototypes and side surface prototypes, rubber molds are produced by reversing, and the design surface molds and side molds are produced from the rubber molds by reversing the required number of molds. Assemble in a ring shape so that it is almost a perfect circle on the design surface basis, and fit the side mold corresponding to the groove on the design surface mold without any gaps, and fix the outer circumference to the inner diameter larger than the circumscribed circle diameter of the side mold tip. A ring casting in which a piece metal mold is connected in a ring shape by casting a molten metal and casting a metal mold, and shaping the three sides of the piece mold, the design surface and the left and right side parts, by casting. After correcting the dimensions and turning the outer periphery of the ring casting, the back and top and bottom surfaces of multiple piece molds fitted in one ring are machined, and the design surface mold is also used for the second ring. Repeat the process of assembling the ring Thus, a necessary number of piece mold shapes are obtained, and the obtained piece molds are assembled in a holder.

  Further, in the invention of claim 2, when manufacturing a tire molding die by the method of claim 1, the number of ring castings to be cast to obtain one set of piece molds is two rings. When the first ring piece mold is completed, the piece mold is temporarily assembled, the circumferential dimensions, etc. are measured, and the first ring piece mold is assembled to the assembly dimensions. If there is a deficiency that is outside the allowable tolerance of the mold, correct the deficiency by reducing the depth of fitting the side mold into the groove of the design surface mold when manufacturing the second ring, or correct the side In the mold manufacturing process, the shortage of meat stealing material is affixed to the side rubber mold to correct the shortage, and if there is an excess, the side mold for the second ring has the appropriate thickness. Paste meat stealing material that does not melt into the molten alloy to be cast Therefore, the excess amount is corrected, or the excess amount is corrected by sticking an excessively thick wall stealing material to the side surface mold in the side rubber mold manufacturing process. .

  According to a third aspect of the present invention, there is provided a method for manufacturing a tire molding die of a piece mold assembling method, and a design surface shape corresponding to one piece mold and split surfaces of the piece molds at both circumferential ends. It is possible to create a design surface prototype by alternately engraving multiple pieces on the same prototype for the shape of the groove, and to fit the groove shape that has been dug, and after fitting, the design surface prototype Prototypes for side surfaces with surface shapes corresponding to both circumferential ends of the piece mold are prepared separately so that the height dimension protruding from the radial dimension of the piece mold is larger than these, From the design surface mold and the side pattern mold, each rubber mold is inverted, and the design surface mold and side mold are manufactured from the rubber mold by the required number of mold reversals, and the mold is baked and dried. Fit the corresponding side mold into the groove. The design surface mold unit is surrounded by a casting frame, a molten metal is cast between the mold and the casting frame, a segment casting is casted, and the design surface and left and right side surfaces of the piece mold are cast. By forming and shaping, a plurality of segment castings are set and held on the lathe so that they are concentric with respect to the design surface part, and the tilt between the upper and lower molds is minimized, and each casting outer periphery is lathe processed. Processes the back and top and bottom surfaces of multiple piece molds fitted in the segment casting, and repeats until the required number of piece molds is obtained, and assembles the obtained piece molds in the holder It is what.

  According to the invention of claim 4, in manufacturing a tire molding die by the method of claim 3, the number of segments to be cast at one time is adjusted to the number of segments to be processed at one time by lathe processing, and one lathe processing is performed. At the time of completion, temporarily assemble the obtained piece mold, measure the circumferential dimension, etc., if there is a shortage of size that deviates from the tolerance of the tire mold, at the time of production for the second time, By shortening the depth of fitting the side mold into the groove of the design surface mold, the shortage is corrected, or by attaching the meat stealing material to the side rubber mold in the side mold manufacturing process, Correct the deficiency, and if there is an excess, stick a meat stealer that has the appropriate thickness and will not be fused to the molten alloy to be cast on the second side mold. Correct the excess or add excess to the side mold in the side rubber mold manufacturing process. It is characterized by correcting the excess by pasting a thick stealing material.

  In the invention of claim 2, the first ring and the second ring are used, and in the invention of claim 4, the upper and lower relations of the design surface mold and the side surface mold are reversed with each other by half of the number of design surface molds. Casting can offset the dimensional error due to the difference in contraction between the upper and lower molds during casting for one set of piece molds. In addition, in the invention of claim 1 or 3, by providing an auxiliary groove shape for air escape promotion provided on the side surface portion of the piece mold and an uneven shape corresponding to a minute gap shape by attaching to the side surface mold by a manufacturing method, The shape can be formed on the side surface of the piece mold by a casting method.

  Furthermore, it is possible to process the piece fitting surface portion of the side surface mold so that the unevenness of 0.01 to 0.05 mm remains, and to make the directionality of the unevenness not coincide on the left and right side surfaces of the piece mold.

  According to the first aspect of the present invention, the mating surfaces of the piece castings can be cast and formed with a predetermined gap shape without machining, except for the design surface and the left and right mating surfaces. These three surfaces (upper and lower surfaces and back surface) can be turned. For this reason, a piece mold assembly type tire molding mold having a slit vent with an optimum width can be manufactured more easily and at a lower cost than in the past. According to the second aspect of the present invention, it is possible to solve the problems caused by the casting shrinkage variation that may occur in the first aspect of the invention, and to minimize the dimensional error. According to the third aspect of the present invention, since a plurality of segment castings are manufactured without creating a ring casting, the assembly man-hour and casting weight of the mold can be reduced, and the dimensional accuracy can be improved. The advantages of other claims will be described together with the embodiments.

(Invention of Claim 1)
In this embodiment, a necessary number of piece molds 1 as shown in FIG. 6 are manufactured, and these are combined to manufacture a mold for tire molding of a piece mold assembly system. The left side of FIG. 6 is a plane divided piece mold, and the right side is a curved divided piece mold. If you want to manufacture such a piece mold 1, “design surface”, “side surface (right)”, “side surface (left)” are formed by “casting”, “back”, “upper surface”, “lower surface” Is formed only by lathe machining. Hereinafter, each step will be described with reference to schematic views.

  FIG. 7 is an explanatory diagram of the prototype process, with the left side being a cross section in the week direction and the right side being a cross section in the width direction. First, the design surface prototype 4 is created by alternately engraving the design surface shape 2 and the groove shape 3 corresponding to one piece mold into the same prototype for a plurality of pieces. This prototype has a central angle of about 30 to 60 degrees, and is created as a shape in which the shape of the tire design surface is enlarged by the amount corresponding to the mold casting shrinkage. Here, the groove shape 3 is formed at a position corresponding to the dividing surface of the piece mold 1 at both ends in the circumferential direction of the design surface shape 2. The depth of the groove shape 3 is the depth at which the original is carved about 2 to 50 mm from the deepest part of the design surface shape 2. Further, a side surface prototype 5 that can be fitted into the groove shape 3 carved in the design surface prototype 4 and has a surface corresponding to the side surface shape of the piece mold 1 is also created at the same time.

  Here, the numerical regulation of “depth 2 to 50 mm” is that if the depth is less than 2 mm, the side surface prototype 5 cannot sufficiently cut and separate the groove portion of the design surface prototype 4, and if it exceeds 50 mm, This is because when the design surface mold is removed in the next process, the risk of breaking the mold due to the rubber shape (undercut) of the groove is increased. The numerical regulation of “30-60 deg” is less than 30 deg., The work efficiency of the subsequent process is poor, and if it exceeds 60 deg, when the design surface mold is removed from the rubber mold, the mold is molded in the rubber undercut shape. This is to increase the risk of breaking.

  Next, as shown in FIG. 8, a design surface rubber mold 6 and a side rubber mold 7 are cast-inverted from the design surface prototype 4 and the side surface prototype 5. The design surface rubber mold 6 can be basically handled by the same structure as that used in the conventional gypsum casting method. The side rubber mold 7 uses a backing frame that can minimize the thickness of the rubber layer and tries to transfer the shape with high dimensional accuracy.

  Next, as shown in FIG. 9, the design surface mold 8 and the side surface mold 9 are casted using the manufactured rubber mold. Either a plaster mold or a ceramic mold may be used. At the time of each mold, the fitting between the design surface mold 8 and the side surface mold 9 is confirmed. The finished mold is dried and fired.

  Next, as shown in FIG. 10, the finished design surface mold 8 is assembled in a ring shape so that the design surface portion diameter of the mold becomes a perfect circle. However, it is not possible to assemble a mold for the required number of pieces with one ring (because there is an extra groove shape). When assembling the design surface mold 8 into a perfect circle, if the design surface mold 8 alone cannot be assembled to a 360 deg degree, a dummy mold is appropriately sandwiched and assembled into a ring shape. When the design surface mold 8 is assembled, the side surface mold 9 corresponding to the groove is fitted and joined to the design surface mold 8 as shown in the lower part of FIG. 10 (using a method such as nailing, screwing, or wedge fastening). Bonding).

  Next, as shown in FIG. 11, a ring-shaped casting frame 10 is installed on the outer periphery of the mold that has been assembled into a ring shape, and a molten metal is filled (cast) between the mold and the casting frame. The inner diameter of the casting frame 10 is about 20 to 100 mm larger than the outermost diameter (φD) of the mold. If it is less than 20 mm, the molten metal cannot be sufficiently filled in each piece during casting, and if it exceeds 100 mm, the material loss in post-processing becomes too large.

  Next, as shown in FIG. 12, in the state of the obtained ring casting 11, the diameter and roundness of each part of the design surface part of the piece casting are measured. When the diameter / roundness is out of the allowable tolerance range, diameter correction and roundness correction are performed in a ring state. That is, when both ΦA, B, and C are smaller than the target diameter, diameter expansion correction is performed by an expander as shown in FIG. 13, and when both ΦA, B, and C are larger than the target diameter, a restraining ring as shown in FIG. Diameter reduction correction is performed using the difference in the thermal expansion coefficient of the ring casting, and when ΦA, C is the opposite of the target diameter, the correction is performed by combining both as shown in FIG. In this process, a method for correcting the roundness characteristic is described in detail in Japanese Patent Application Laid-Open No. 2004-42505, which is Patent Document 5.

  The casting after the dimensional correction in the ring state is processed with a lathe as shown in FIG. 16, and the back surface, top surface, and bottom surface of the piece are shaped. In this processing, the outer peripheral processing diameter is defined in the form of the thickness on the basis of the design surface of the piece casting. With this processing standard, the remaining diameter error in the ring casting state is offset. Even after the outer periphery machining, if the piece castings can be kept in the “connected” state, the lathe machining work is easy to perform. Therefore, as shown in FIG. 17, the prototype is built in such a way that “ears” are attached directly below the top and bottom surfaces It is desirable to keep in. Ear parts will be manually removed and finished later. In addition, the side mold 9 may be dealt with by opening a connecting hole.

  10 to 17 described above are repeated to obtain the necessary number of piece molds 1. Finally, the completed piece mold 1 (processed piece casting) is assembled to the holder 12 to complete the tire mold. When the piece mold 1 is assembled to the holder 12, if the target diameter is not achieved, correction is performed in this step. That is, when the design surface diameter after the temporary assembly is larger than the target diameter, as shown in FIG. Also, if there is an excessive gap between piece molds 1 after temporary assembly, refill the gap with a pad such as a shim or replace it with a newly manufactured (large) piece mold 1 as needed. To deal with. Since the former can be said to be much easier in terms of handling man-hours, it is possible to produce piece castings so that the diameter of the design surface is slightly larger than the target diameter in the temporarily assembled state of the piece mold 1. One point.

  As described above, according to the first aspect of the present invention, the mating surfaces of the piece castings can be cast and formed with a predetermined gap shape without being machined. Three surfaces (upper and lower surfaces and back surface) other than the fitting surface can be turned. For this reason, it is possible to manufacture a tire molding die of a piece die assembling method having a gap of an optimum width more easily and at a lower cost than before.

(Explanation of claim 2)
In the invention of claim 1 described above, in order to cast and manufacture a piece casting for one set of tire molds as described in paragraph 0030, it is essential to manufacture a casting of two or more rings. Also, in the last part die assembly process, the piece mold 1 is manufactured by casting, so the “casting shrinkage variation” creates excessive gaps between the pieces, and the design after assembly. There is a high possibility that the surface diameter is likely to become too large, and a considerable correction work is required.

The invention of claim 2 is to minimize this problem.
-Set the original shape so that one set of piece molds can be obtained by casting two rings,
・ Assemble the piece mold that was cast on the first ring,
・ Reflect the dimension result (large or small error with respect to the target dimension) to the casting of the second ring,
・ Minimizes dimensional errors when assembling one set of piece molds.
Claim 2 basically differs from Claim 1 in the final part, and the steps up to FIG. 17 are the same, so only the different steps will be described below.

  As shown in FIG. 19, the piece mold 1 obtained by casting and processing the first ring is provisionally assembled to the holder 12, and the circumferential development length (Cac) or the string dimension (Wac) in the piece assembled state Measure. At this time, when an error with respect to the target dimension is confirmed, the error amount is converted into a value Δp of one piece die unit. Considering the development length Cac in FIG. 19, when the target development length is C, Δp = (Cac−C) / 8.

There are the following two countermeasures when Δp is a negative value. The first is adjustment of the fitting state of the side surface mold 9 into the design surface mold 8. That is, as shown in FIG. 20, by sandwiching a shim (lifting) 13 having a thickness T between the design surface mold 8 and the side surface mold 9, the circumferential development dimension of the piece in the mold can be increased.
When the angle of the side mold 9 is θ, the thickness T of the shim 13 required to increase the circumferential development length by Δp for one piece mold is T = Δp / {2 · tan (θ / 2)}. The shim used here is preferably made of a material that does not melt to the molten metal because it may come into contact with the molten metal during casting. (Various steel materials)

  The second countermeasure when Δp is a negative value is the installation of the meat stealer 14 on the side rubber mold 7. As shown in FIG. 21, the side mold 9 is formed with the meat stealer 14 having a thickness Δp attached to one side of the side rubber mold 7 or the meat stealer 14 having a thickness Δp / 2 attached to both sides. This is a method of increasing the circumferential development length per piece mold by Δp by reversing the casting. The meat stealing material 14 used here may be of any material as long as the mold can be cast-reversed, and may be a polyethylene sheet or aluminum foil.

  The first countermeasure when Δp is a positive value is to stick a meat stealing material 15 having a thickness Δp on one side of the side mold 9 as shown in FIG. 22, or stealing a meat having a thickness Δp / 2 on both sides. This is a method of attaching the material 15. Since the meat stealing material 15 used here directly touches the molten metal during casting, it is essential that the material is not melted by the molten metal. For example, various steel materials are preferably used. Further, as a method for fixing the meat stealing material 15 to the side mold 9, there are methods such as adhesion by a raw mold material or a method in which holes are punched in various places of the meat stealing material and fixed by nailing here. .

  When Δp is positive, the second countermeasure is that after Δp meat stealing is performed on one side surface of the side surface prototype 5 or Δp / 2 meat stealing is performed on both side surfaces of the side surface prototype 5, as shown in FIG. This is a method of remanufacturing from the side rubber mold 7. The meat stealing material used here may be any material as long as the rubber mold can be cast-inverted. For example, various adhesive tapes may be used.

  After the above, the second ring piece casting may be manufactured by repeating the steps shown in FIG. As a result, the circumferential dimensional error generated in the piece casting in the casting of the first ring can be offset by the casting of the second ring, and the circumferential dimensional error as one set of piece casting can be minimized. is there.

(Invention of Claim 3)
In claims 1 and 2 described above, a piece mold is obtained by assembling the manufactured mold in a ring shape aimed at a perfect circle and casting a ring casting, and then processing the outer periphery of the ring casting. , Claim 3 is basically the same up to the mold manufacturing process, casting the manufactured mold in one segment unit, and processing the finished segment castings one by one on the lathe on the top and bottom and back It is related to the technology of manufacturing a piece mold for the minute. Since claim 3 is the same as claim 1 up to the step shown in FIG. 9, only FIG. 10 and after will be described.

Especially when casting ferrous alloys,
1) Even when cast into a ring shape, the strength characteristics of the alloy are too high, and it is difficult to correct the diameter and roundness of the ring casting.
2) When cast in a ring shape, the casting weight increases, the molten metal solidification time becomes too long, and the casting quality tends to deteriorate.
For this reason, there are cases where the method of assembling and casting the mold in a ring shape as in claim 1 cannot be adopted.
In such a case, as shown in FIG. 24, according to the invention of claim 3, one unit of the mold is surrounded by a casting frame, and the segment casting 16 is cast. Here, the positional relationship between the casting frame and the mold is the same as in the case of claim 1.

  In the invention of claim 3, as shown in FIG. 25, a plurality of segment castings 16 produced previously are set on a lathe. At this time, each segment casting 16 is placed on the lathe bed so that the design surface radius in the vicinity of both ends of each segment casting 16 becomes the target radius (Rcl) and there is no tilt between the upper and lower molds (Rtop = Rbot). Attach to. Then, as shown in FIG. 26, the outer periphery is processed so that the piece casting has a predetermined thickness on the basis of the design surface. The steps of FIGS. 10 to 12 are repeated until the necessary number of piece molds is obtained, and the following is the same as the step of claim 1.

The invention of claim 3 is compared with the invention of claim 1,
1) There is no need to assemble a mold. (Reduction of mold assembly man-hours)
2) There is no need to cast in a ring state. (Small casting weight is required)
3) Dimensional accuracy can be improved by adjusting the setting position of the segment casting to the processing machine during peripheral processing without correcting the casting dimensions with external force. (High dimensional correction is not required)
This has the advantage that it can easily cope with the production of iron-based cast tire molds using the ceramic mold method.

(Invention of Claim 4)
Even when the invention of claim 3 is carried out, the technique of claim 2 is used, which is a technique for canceling out the dimensional error of the piece mold that has been completed in advance as in claim 1 in the process of casting production in the follow-up. I can do it. The technical contents are the same as those described in claim 2, and will be omitted.

(Claim 5)
In the casting method, it is essential that the molten metal solidification in the mold-casting frame has a directivity such as the direction of the hot metal portion from one end of the product portion so that no shrinkage defects are generated in the product portion. There are two general tire mold casting methods: gravity casting and low pressure casting. 27 and 28 explain gravity casting and low-pressure casting. Gravity casting method has the direction of rough melt solidification from bottom to top and low-pressure casting method from top to bottom. Become. In castings, there is a tendency that the portion where the solidification of the molten metal is delayed generally shrinks better. This is because the part where solidification is delayed is due to the difference between the casting and the mold, and the mold is likely to be (creep) deformed, or the mold is transformed and contracted by heat input from the casting. In a tire mold casting using such a casting method, the problem is that the dimensions of the casting differ between the upper and lower molds. (In the case of gravity casting, the upper side of the casting will shrink well, and in the case of low pressure casting, the lower side of the casting will shrink well.

  Since the same phenomenon occurs in the piece casting of the present invention, the piece casting may be used particularly when using the techniques of claims 2 and 4 to assemble a piece mold with high accuracy in an as-cast state. There is a risk of generating a gap between the piece castings at the contracted portion. The invention of claim 5 relates to a technique for solving the problem.

  FIG. 29 is an explanatory diagram when the method of claim 5 is applied to the invention of claim 1, and casting is performed by reversing the vertical relationship between the design surface mold and the side surface mold in the first ring and the second ring. . FIG. 30 is an explanatory diagram when the method of claim 5 is applied to the invention of claim 3. In the first and second rounds, casting is performed by reversing the vertical relationship between the design surface mold and the side mold. By using this technique, the difference in shrinkage between the upper and lower molds in the casting plan is offset, and a piece mold assembly with good accuracy can be performed in the as-cast state.

(Invention of Claim 6)
As shown in FIG. 31 and FIG. 32, when a shallow slit groove shape 17 or a half-moon shaped auxiliary groove shape 18 is to be provided on a part of the side surface of the piece, the corresponding slit groove shape or By attaching the inverted shape member 19 having a half-moon shape, it is possible to apply the corresponding shape by casting. The invention of claim 6 is a manufacturing method according to claims 1 to 5, characterized in that the side mold of the side mold is provided with the air vent groove shape required for the side part of the piece mold. .

  When a convex member is pasted on the side mold, the part becomes a so-called “undercut shape”, which may be an obstacle to casting mold reversal, but the side mold is inverted to the rubber mold. In the first place, the slit groove and auxiliary groove required for the piece mold can be utilized for mold production (rubber mold) for two reasons: the depth is as shallow as 0.02 to 2 mm. (Removal from the mold)), there is almost no problem.

The merit of being able to give the air vent groove shape to the piece mold by following the pasting to the side mold is
1) By using a commercially available tape material, etc., it is possible to easily give the desired groove shape with an accuracy of the order of 0.01mm. 2) There is no need to remanufacture from the side mold when changing the mold design. It only has to be replaced.

(Invention of Claim 7)
One of the advantages of the above-described piece assembly type mold is that air is released from the gap between the piece assembly surfaces during tire molding. Therefore, the surface accuracy of the side surface mold determines the gap between the piece dies. When a piece mold is manufactured by a casting method using the techniques of claims 1 and 3, the surface property (roughness state) of the side surface of the piece mold is transferred as an inverted shape of the side surface mold. When the side surface mold is processed by a ball end mill, an uneven shape (cutter mark) like a concave lens is formed on the original surface as shown in FIG. 33, and in a piece casting, an uneven shape like a convex lens is formed on the side of the mold. It is formed. Strictly speaking, the unevenness depth on the side surface of the piece casting is Δs × (1−β): β is a shrinkage rate of the casting, where Δs is the unevenness depth of the side surface prototype. (Normally, Δs is as small as about 0.01 to 0.1 mm, and β is as small as 10/1000 to 30/1000, so even casting can be regarded as approximately Δs.)

  When the side surface original cutter marks transferred to the piece mold have the same directionality between adjacent piece molds, the problems shown in FIGS. 34 and 35 occur. In other words, since it is impossible to control with the cutter mark positioned precisely, the periodicity of the cutter mark is slightly shifted between adjacent pieces (a phase difference is produced) at the time of mold matching between piece molds. As shown in FIG. 35, the inter-piece gap Δ greatly varies.

  When assembling a piece mold of about 100 pieces in one set to make a tire mold, if this gap variation occurs between the pieces, a phenomenon of air discharge inhibition (bubble defects in the tire molded product) will occur locally during tire molding. Or excessive rubber burrs are likely to occur in the tire. When molding non-spy tires, it is necessary to control the gap between the piece molds in units of 0.01 mm, so there is a risk that a variation of only 0.01 mm may be fatal. Claim 7 provides a technique for overcoming the above-described problems and for providing a uniform gap between the piece molds.

  Specifically, it may be dealt with as shown in FIGS. FIG. 36 shows a method for processing the side pattern so that the direction of the cutter mark is different between adjacent piece molds. As a result, no matter how the piece molds are fitted, the gap formed by the irregular shape of the cutter mark can be maintained at 2 · Δs, and the high accuracy required for non-spy tire molds It is possible to control the gap between piece dies. Alternatively, the direction of the cutter mark may be changed as shown in FIG. 37, or one side surface prototype may be manufactured using wire electric discharge machining or the like as shown in FIG.

  It should be noted that, in claim 7, the numerical control as “0.01-0.05 mm unevenness” means that a sufficient air exhaust gap between the piece dies even when using the invention of claim 7 below 0.01 mm This is because if the thickness exceeds 0.05 mm, a large gap is excessively attached, and rubber burrs are inserted between the piece molds when the tire is molded.

(Tire molds manufactured through all examples)
As shown in FIG.
Pitch variations A, B, C, D, E 5 types
17 pitches A, 17 pitches B, 13 pitches C, 11 pitches D, 11 pitches E total 69 pitch / 1 ring sectional mold (sector division number 7)
Piece molds are casted for each pitch and ring assembly (piece side shape is a gently curved surface)

(Outline of piece mold casting method)
(prototype)
Material: Synthetic wood (Chemiwood)
Design surface prototype: 3 types (A, B, C, D, E pitch mixed pattern 3 types)
Side mold: 10 types (corresponding to the above three mold grooves) Manufactured by NC processing machine (When the mold is assembled in a ring, one set of piece molds has a prototype angle that can be manufactured within 2 rings)
The casting shrinkage ratio was 11-15 / 1000 for each part of the original mold, and the original mold was defined by expanding the mold dimensions accordingly (rubber mold).
Backing material: Gypsum material Rubber material: Condensed silicone rubber Rubber layer thickness 15mm

(Aluminum piece casting)
Mold material: Noritake Gypsum G-6 non-foamed gypsum (mixed with 60 parts by weight of water for 100 parts by weight of powder)
Alloy material: AC4C (Si: 7%, Mg: 0.4%, remaining Al)
(Iron piece casting)
Mold material: Ceramic mold material with ethyl silicate 40 as binder Alloy material: FCD600 (C: 3.4%, Si: 1%, remaining Fe spheroidal graphite cast iron)
The casting method adopted the gravity casting method for both aluminum and iron.

(Example 1) Examples of Claims 1, 2, 5, 6, and 7 Using the technique of Claim 1, the above-described piece assembly type tire mold was manufactured by an aluminum alloy casting method using a plaster mold. . On this occasion,
1) At the time of processing the side surface prototype, the surface roughness of the prototype is generated by about 0.02 mm, and the direction of the cutter mark is shifted by 90 degrees between the side surfaces of adjacent pieces (use of the invention of claim 7)
2) For the side model, three pieces of aluminum foil with a width of 10 mm, a length of 50 mm, and a thickness of 0.02 mm are attached to one side, and a piece casting is set so that a slit groove with a width of 10 mm and a depth of 0.02 mm can be formed. (Use of invention of claim 6)
3) After casting of the first ring, the upper and lower surfaces of the piece mold are machined with an NC lathe, and the completed piece mold is temporarily assembled in a holder, and the circumferentially expanded length per piece mold When the error relative to the target value was measured, it was about 0.01 mm smaller than the target value. For this reason, when assembling the second ring mold, a 0.2 mm thick SK-3 material (tool steel) shim (lifting material) is sandwiched between the design surface mold and the side mold (use of the invention of claim 2) )
4) For the second ring, the mold was assembled upside down with respect to the first ring, and casting and lathe processing was performed. (Use of invention of claim 5)
In both the first and second rings, the ring castings were subjected to diameter expansion correction in the ring state, and the diameter error with respect to the target diameter was set to less than ± 0.2 mm, and then lathe processing was performed on the upper and lower surfaces of the piece and the back surface.

Fit the finished piece mold into the holder, heat it to 250 ° C, apply external force (force in the radial center direction) through the holder, crush the gap between the pieces of the piece mold due to casting distortion, and attach the tire mold Completed.
The tire mold thus obtained had characteristics as shown in Table 1.

(Comparative Example 1) Comparative Example when Claim 5 was not Used in Example 1 When a tire mold was manufactured without performing 4) in Example 1, the characteristics of the obtained tire mold are shown in Table 2. As shown. There was a tendency for the amount of clearance between pieces on the upper mold side to be large, and the roundness characteristics were slightly deteriorated.

(Example 2) Examples of Claims 3, 4, 5, 6, and 7 Using the technique of Claim 3 for the above-described piece assembly type tire mold, iron-based alloy (FCD600) casting using a ceramic mold Produced by the law. On this occasion,
1) At the time of processing the side surface prototype, the surface roughness of the prototype is generated by about 0.02 mm, and the direction of the cutter mark is shifted by 90 degrees between the side surfaces of adjacent pieces (use of the invention of claim 7)
2) For the side model, three pieces of aluminum foil with a width of 10 mm, a length of 50 mm, and a thickness of 0.02 mm are attached to one side, and a piece casting is set so that a slit groove with a width of 10 mm and a depth of 0.02 mm can be formed. (Use of invention of claim 6)
3) After casting the first batch, the upper and lower surfaces of the piece mold are machined with an NC lathe, and the completed piece mold is temporarily assembled in a holder, and the circumferentially expanded length per piece mold When the error relative to the target value was measured, it was about 0.02 mm smaller than the target value. Therefore, when assembling the mold for the second batch, a 0.3 mm thick SK-3 material (tool steel) shim (lifting material) is sandwiched between the design surface mold and the side mold (use of the invention of claim 2) )
4) In the second batch, the casting was turned upside down and the lathe was machined. (Use of invention of claim 5)

When the finished piece mold was inserted into the holder, it was confirmed that it was about 0.01 mm larger per mold than the target value for the circumferential development length. The tire mold was completed by sandwiching the grains and carrying out hand-grinding and cutting.
The tire mold thus obtained had the characteristics shown in Table 3. Compared to Example 1, the reason why the gap accuracy and roundness characteristics are inferior is that the casting was not corrected for diameter and roundness by external force, and by casting an iron-based alloy with a high casting temperature, This is due to the increased casting distortion.

  As described above, according to the present invention, a piece assembling mold for molding a tire can be manufactured by a casting method more easily and cheaply than the conventional manufacturing method. It can be said that the present invention provides a technique that can provide a mold for molding a tire with high performance and high appearance quality at low cost, and it can be said that the technical influence on the corresponding industry is extremely large.

It is explanatory drawing of the machining method of a laminated material among the slit vent type tire metal mold manufacturing methods. It is explanatory drawing of the casting method among slit vent type tire metal mold manufacturing methods. It is explanatory drawing of the piece joining method among slit vent type tire metal mold manufacturing methods. It is explanatory drawing of the dissimilar metal piece casting method among slit vent type tire metal mold manufacturing methods. It is explanatory drawing of a partition plate division piece casting method among the slit vent type tire metal mold manufacturing methods. It is a perspective view which shows the piece metal mold | die manufactured by this invention. It is explanatory drawing of the original pattern process in embodiment of invention of Claim 1. It is explanatory drawing of the rubber-type process in embodiment of invention of Claim 1. It is explanatory drawing of the casting_mold | template process in embodiment of invention of Claim 1. It is explanatory drawing of the casting_mold | template process in embodiment of invention of Claim 1. It is explanatory drawing of the casting_mold | template process in embodiment of invention of Claim 1. It is explanatory drawing of the dimension measurement process in embodiment of invention of Claim 1. It is explanatory drawing of the dimension correction process in embodiment of invention of Claim 1. It is explanatory drawing of the dimension correction process in embodiment of invention of Claim 1. It is explanatory drawing of the dimension correction process in embodiment of invention of Claim 1. It is explanatory drawing of the outer periphery processing process in embodiment of invention of Claim 1. It is explanatory drawing of the ear attachment in embodiment of invention of Claim 1. It is explanatory drawing of the piece metal mold assembly process in embodiment of invention of Claim 1. It is explanatory drawing of the 1st ring temporary assembly process in invention of Claim 2. It is explanatory drawing of the 1st countermeasure when a dimension is minus. It is explanatory drawing of the 2nd countermeasure when a dimension is minus. It is explanatory drawing of the 1st countermeasure when a dimension is plus. It is explanatory drawing of the 2nd countermeasure when a dimension is plus. It is explanatory drawing of the casting process in embodiment of invention of Claim 3. It is explanatory drawing of the outer periphery processing process in embodiment of invention of Claim 3. It is explanatory drawing of the outer periphery processing process in embodiment of invention of Claim 3. It is explanatory drawing of a gravity casting method. It is explanatory drawing of a low pressure casting method. It is explanatory drawing at the time of applying the method of Claim 5 to invention of Claim 1. It is explanatory drawing at the time of applying the method of Claim 5 to invention of Claim 3. It is explanatory drawing of embodiment of Claim 6. It is explanatory drawing of embodiment of Claim 6. FIG. 9 is an explanatory diagram of a problem for explaining claim 7; FIG. 9 is an explanatory diagram of a problem for explaining claim 7; FIG. 9 is an explanatory diagram of a problem for explaining claim 7; It is explanatory drawing of embodiment of Claim 7. It is explanatory drawing of other embodiment of Claim 7. It is explanatory drawing of other embodiment of Claim 7. It is a dimensional drawing of a tire mold manufactured through all the examples. It is process explanatory drawing of the prior art of patent document 6. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piece mold 2 Design surface shape 3 Groove shape 4 Design surface prototype 5 Side surface mold 6 Design surface rubber mold 7 Side rubber mold 8 Design surface mold 9 Side surface mold 10 Ring-shaped casting frame 11 Ring casting 12 Holder 13 Shim 14 Meat stealing Material 15 Stealing material 16 Segment casting 17 Slit groove shape 18 Auxiliary groove shape 19 Inverted shape member

Claims (7)

In the manufacturing method of the tire mold of the piece mold assembly method,
Design surface prototype corresponding to one piece mold and groove shape corresponding to the split surface of the piece mold at both ends in the circumferential direction are alternately engraved for multiple pieces on the same prototype. A piece mold that can be fitted into a groove shape that has been created and dug, and the height dimension protruding from the design surface mold after fitting is larger than the radial thickness dimension of the piece mold Separately make a prototype for the side with a surface shape corresponding to both circumferential end faces of
From these design surface prototypes and side surface prototypes, rubber molds are produced by reversing, and the design surface molds and side molds are produced from the rubber molds by reversing the required number of molds. Assemble in a ring shape so that it is almost a perfect circle on the design surface basis, and fit the side mold corresponding to the groove on the design surface mold without any gaps, and fix the outer circumference to the inner diameter larger than the circumscribed circle diameter of the side mold tip. A ring casting in which a piece metal mold is connected in a ring shape by casting a molten metal and casting a metal mold, and shaping the three sides of the piece mold, the design surface and the left and right side parts, by casting. After correcting the dimensions and turning the outer periphery of the ring casting, the back and top and bottom surfaces of multiple piece molds fitted in one ring are machined, and the design surface mold is also used for the second ring. Repeat the process of assembling the ring Then, a necessary number of piece mold shapes are obtained, and the obtained piece mold is assembled in a holder.   In manufacturing a tire molding die by the method according to claim 1, piece shape arrangement in the original mold is performed so that the number of ring castings to be cast to obtain one set of piece molds is two rings, 1 When the piece mold for the ring is completed, the piece mold is temporarily assembled, the dimensions in the circumferential direction, etc. are measured, and the assembly dimensions for the first ring piece mold are outside the allowable tolerance of the tire mold. If a shortage occurs, correct the shortage by reducing the depth of fitting the side mold into the groove of the design surface mold during the production of the second ring, or use the side rubber in the side mold manufacturing process. The shortage of meat stealing material is affixed to the mold, and the shortage is corrected. If an excess occurs, the side mold for the second ring has the appropriate thickness and is melted into the molten alloy to be cast. Paste meat stealing material that you never wear and correct the excess Or, in the side rubber mold manufacturing process, manufacturing the mold for tire molding of piece assembly system, which corrects the excess by sticking the excess thickness of the stealer to the side mold Method. In the manufacturing method of the tire mold of the piece mold assembly method,
Design surface prototype corresponding to one piece mold and groove shape corresponding to the split surface of the piece mold at both ends in the circumferential direction are alternately engraved for multiple pieces on the same prototype. A piece mold that can be fitted into a groove shape that has been created and dug, and the height dimension protruding from the design surface mold after fitting is larger than the radial thickness dimension of the piece mold Separately make a prototype for the side with a surface shape corresponding to both circumferential end faces of
From these design surface prototypes and side surface prototypes, the rubber molds are produced by reversing, the design surface molds and side molds are produced from the rubber molds by the required number of molds, and the molds are baked and dried. Each side mold corresponding to the groove part is fitted and fixed in each unit, one unit of the design surface mold is surrounded by a casting frame, a molten metal is cast between the casting mold and the casting frame, a segment casting is produced by casting, a piece mold The design surface part and left and right side surface parts are cast and shaped, and a plurality of segment castings are set and held on the lathe so that they are concentric with respect to the design surface part and the collapse between the upper and lower molds is minimized. By lathing the outer periphery of the casting, the back and top and bottom surfaces of multiple piece molds fitted in each segment casting are machined and repeated until the required number of piece molds is obtained. Assembled piece mold in holder Method of manufacturing a tire mold piece assembly method, wherein.   In producing a tire molding die by the method according to claim 3, the number of segments to be cast at one time was adjusted to the number of segments to be processed at one time by lathe processing, and obtained when one lathe processing was completed. Temporarily assemble the piece mold, measure the circumferential dimension, etc., and if there is a shortage that is outside the allowable tolerance of the tire mold, the side mold will be used as the groove in the design surface mold during the second production. Correct the deficiency by reducing the depth of fitting into the surface, or correct the deficiency by sticking the deficient meat stealing material to the side rubber mold in the side mold manufacturing process, and excess If there is a minute, stick the meat stealing material that has the appropriate thickness on the second side mold and will not be fused to the molten alloy to be cast, and correct the excess or the side In the rubber mold manufacturing process, an excessive amount of meat stealing material is attached to the side mold The manufacturing method of the tire molding die of the piece assembly system characterized by correcting the excess by attaching.   Half of the number of design surface molds is cast with the design surface mold and side molds reversed in the vertical relationship with each other. The method for manufacturing a tire molding die of the piece assembly system according to claim 2 or 4, wherein the offset is offset.   Auxiliary groove shape for air escape promotion provided on the side surface of the piece mold and uneven shape corresponding to the minute gap shape are attached to the side mold by the manufacturing method, and the casting mold method is applied to the side surface of the piece mold. 4. The method for manufacturing a tire molding die of the piece assembly method according to claim 1 or 3, wherein the shaping is performed.   The side surface mold piece fitting surface portion is processed so as to leave an unevenness of 0.01 to 0.05 mm, and the directionality of the unevenness is not matched on the left and right side surfaces of the piece mold. Item 4. A method for manufacturing a die for tire molding according to item 1 or 3.

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