JP3708812B2 - Method for manufacturing tire mold having fine recess - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention provides a method for molding a tire.Tire moldFor details on the manufacturing method of the above, in detail, fine grooves such as vent grooves and material escapes necessary for tire manufacture are formed.PreparedtireMoldIt relates to the manufacturing method.
[0002]
[Prior art]
For example, as shown in FIG. 2, the tire 21 has a rib 22 that is a thick groove in the circumferential direction, a lug 23 that is a thick groove in the width direction, and a width of 0.1 to 0.1 for the purpose of improving grip force and drainage. It is common to form various groove shapes such as sipe 24 which is a narrow groove of about 3.0 mm. Accordingly, a mold for molding a tire (hereinafter referred to as “tire mold”) is formed with convex portions (bones, sipe blades) complementary to these groove shapes. Apart from this, there may be a case where a fine and complicated concave portion (hereinafter referred to as “fine concave portion”) for smoothly forming a tire such as a vent groove and material escape is formed.
[0003]
As shown in FIG. 3, the vent groove 31 is a fine recess having a width of 0.6 to 3.0 mm and a depth of about 0.6 to 3.0 mm formed at the side end of the bone 32 or sipe blade. In addition to the vent hole (air bleeding hole of about φ0.6 to 1.6 mm) 33, it has a function as an air bleeding mechanism at the time of tire compression molding.
[0004]
As shown in FIG. 4, tire molding is performed by compression molding in which a green tire 34 made of unpolymerized rubber having no groove shape is pressed against a tire mold 35. Therefore, the surface of the tire 34 and the surface of the mold 35 (bones) In some cases, air is enclosed in the closed space 36 formed by the sipe blade and the escape space is lost and a bubble defect (bear) 37 is generated. The vent groove serves as a place for the enclosed air to escape, and has the effect of preventing the occurrence of the bear 37 by guiding the air to the communicating vent hole.
[0005]
On the other hand, the material relief 41 shown in FIG. 5 is a fine recess having a width of 2 to 20 mm and a depth of 2 to 20 mm formed on the contact surfaces 42a and 43a of the upper mold 42 and the lower mold 43 of the tire mold. Thus, it functions as a discharge mechanism for excess material (rubber) generated during compression molding of the tire.
[0006]
When the tire is compression-molded by the upper and lower divided molds, excess material overflows from the mold to the contact surfaces 42a and 43a of the upper mold 42 and the lower mold 43, and the upper mold 42 and the lower mold 43 are in close contact with each other. Therefore, the green tire 45 cannot be bitten, and there is a risk of forming defects such as generation of rubber burrs and an increase in tire width dimension.
The material escape 41 serves as a place for the overflowing excess material 44 to escape, and has the effect of preventing such molding defects.
[0007]
As described above, fine recesses such as vent grooves and material escapes have a favorable effect on tire manufacturing, but it is not always easy to form such fine recesses in the tire mold, and the following problems are raised: Existed.
[0008]
Tire molds have many convex parts such as bones and sipe blades and sharp corners where the convex parts intersect at an acute angle, and the design is complicated. In many cases, it is produced by a casting method in which a molten metal is cast into a mold produced from a tire prototype and then reversed.
As a method of forming a fine recess in a tire mold on the premise of a casting manufacturing method, (1) a method of directly processing a fine recess in a tire mold manufactured from a tire prototype (hereinafter referred to as “first method”) Or (2) a method of forming fine convex portions corresponding to the fine concave portions on the tire prototype (hereinafter referred to as “second method”).
[0009]
However, the first method has a problem that a desired shape cannot be formed when an NC (numerical control) processing machine using a ball end mill or the like is used. In order to improve productivity, it can be said that labor saving by NC processing is indispensable, but tire molds have dimensional variations due to casting shrinkage, which may cause inconsistencies between input data and actual mold shapes. Because it is big.
Further, in the case of the vent groove, the formed portion hits the base of the bone of the mold, so that the tip of the processing tool is difficult to reach, and it can be said that machining itself is almost impossible.
[0010]
On the other hand, the second method has a problem in that the shape accuracy is inevitably lowered due to work variations, and the man-hours for forming the fine protrusions are enormous, and the productivity is extremely low.
[0011]
In the second method, it is necessary to form a fine convex portion on the surface of the prototype, but the convex shape (particularly a fine shape) is difficult to process even with an NC processing machine. 6), the block 51 has an extremely sharp corner 51a as shown in FIG. 6 (a). If it has, it can be said that processing is virtually impossible.
Therefore, conventionally, as shown in FIG. 6 (b), a piece 53 made of a linear member having a circular cross section is stuck in an installation groove 52 formed in advance on the surface of the block 51, or FIG. The fine convex part was formed by the method of sticking the piece 54 which is a linear member with a semicircular cross section on the surface of the block 51 as shown in c).
[0012]
However, in the above-described method, as shown in FIG. 6A, a large number of pieces 55 must be manually joined one after another to form a fine convex portion corresponding to one block 51.
When such complicated processing is performed for each of a myriad of blocks, a reduction in shape accuracy and productivity is inevitable.
In addition, the tire design is a random arrangement of multiple types of pitch designs that expand and contract the basic design in the tire circumferential direction with the aim of reducing vibration and noise during tire rotation and running as much as possible. There are many. In such a case, it is necessary to form fine convex portions having different shapes for each of the plurality of types of pitch designs, and the problems of shape accuracy and productivity become more prominent.
[0013]
In the case of the piece 53 having a circular cross section shown in FIG. 6B, a gap is likely to be formed on the contact surface between the piece 53 and the installation groove 52, and a man-hour for repairing the gap with a putty or the like is required. There is a difficulty. In particular, as shown in FIG. 7, the vent groove piece 56 formed on the surface of the curved block 51 is difficult to match the shape of the block 51 and the piece 56 on the contact surface, and a gap is likely to occur at the time of sticking. .
On the other hand, in the case of a semicircular cross-section piece, it is relatively difficult to generate a gap, and no man-hours for repair are required, but the processing man-hours for halving the cross-sectional linear member into a semicircular section Resulting in.
[0014]
[Problems to be solved by the invention]
As described above, at present, a method capable of producing a tire mold having fine and complicated recesses such as vent grooves and material escapes with high accuracy and high production efficiency (ie, simply and at low cost). Has not yet been found. The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a tire mold having fine and complicated recesses with high accuracy and high production efficiency. An object of the present invention is to provide a method that can be produced (ie, simply and at low cost).
[0015]
[Means for Solving the Problems]
  As a result of diligent investigations on the above-mentioned problems of the prior art, the present inventor casts a mold material into a concave mold prepared in advance by machining, and reverses it, thereby forming the same shape as the fine convex portion.Or a shape that approximates the fine convex portion in a planeBy manufacturing the convex member and sticking the convex member to the surface of the original mold, a tire mold having a fine and complicated concave portion can be obtained with high accuracy and high production efficiency (ie, simply and at low cost). It was found that it could be produced, and the present invention was completed.
[0016]
  That is, according to the present invention,A method for manufacturing a tire mold having a fine recess,By casting and reversing the mold material into a concave mold that has been prepared in advance by machining,For forming fine recesses in tire moldsSame shape as fine convexOr a shape that approximates the fine convex portion in a planeA tire prototype having the fine convex portion is obtained by producing a convex member and sticking the convex member to the prototype surface.A tire mold for obtaining a tire mold having a fine recess by producing a second reversal mold from the tire original mold via the first reversal mold, casting a metal melt into the second reversal mold and reversing the mold. Manufacturing methodIs provided.
[0017]
  Tire of the present inventionMoldIn the manufacturing method ofThe convex member is a convex member having a sharp corner, and the convex memberTheIn the cornerPreferably, a set of divided concave molds corresponding to each of the plurality of divided shapes is produced, and the concave mold is produced by assembling the one set of divided concave molds.The convex member is a convex member having a shape approximating the fine convex portion in a plane, and is preferably attached to the surface of the tire prototype so that the convex member follows the curved shape of the tire prototype,It is preferable to use an elastomer as a mold material cast into the concave mold.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
  Tire of the present inventionMold(Hereafter, simply “Mold". ) Manufacturing method is the same shape as the fine convexOr a shape that approximates the fine convex portion in a planeThe convex member is prepared, and the convex member is adhered to the original surface. Of the present inventionMoldAccording to the manufacturing method, it has a fine and complicated recessTire moldCan be produced with high accuracy and high production efficiency (that is, simply and at low cost). Hereinafter, the present inventionMoldThe manufacturing method will be described in detail.
[0020]
  Of the present inventionMoldThe first feature of the manufacturing method of the present invention is provided with fine convex portions.tireprototype(Hereafter simply referred to as “prototype”.)It is in the point of producing According to this method, fine concave portions that are difficult (or impossible) to be formed by a method of directly machining a mold are formed.prototypeCan be formed by a very simple operation of casting (casting) a molten metal into a mold (which means an inverted mold obtained by reversing the original mold an even number of times), which contributes to an improvement in productivity.
[0021]
  The second feature is the same shape as the fine convex part complementary to the fine concave part of the mold.Or a shape that approximates the surface of the fine convexIt is in the point which sticks the convex member of this to the surface of a prototype. According to this method, there is an advantage that a convex shape that is difficult to be processed even if an NC processing machine is used can be easily formed on the original mold.
[0022]
  The third feature is that the same shape as the fine convex part is obtained by casting the mold material into a concave mold prepared by machining in advance and inverting it.Or a shape that approximates the surface of the fine convexIt is in the point which produces this convex member. This method utilizes the fact that concave machining is easier than convex machining, and once a concave mold is manufactured, the same shape of convex members can be produced in large quantities with good reproducibility. It becomes possible to duplicate.
[0023]
Further, in the above method, even when a plurality of types of pitch designs (that is, fine convex portions having different shapes) exist, it is sufficient to produce a concave mold corresponding to this. This eliminates the need for complicated operations such as forming a fine convex portion by manually joining a large number of pieces to the prototype, thereby contributing to improvement in shape accuracy and productivity.
Furthermore, since the convex member can be produced simply by casting a mold material such as wax or resin into the concave mold, the number of processing steps such as halving the linear member having a circular cross section can be reduced.
[0024]
  Hereinafter, the present inventionMoldThe manufacturing method will be described step by step. The vent groove and the material relief can be basically formed through the same process, although the concave shape and the formation site in the mold (and hence the original mold) are different.
[0025]
(1) Production of concave mold
  First, the same shape as the fine recesses to be formed in the moldOr a shape that approximates the surface of the fine recessA concave mold having a concave portion is prepared. The concave portion can be formed by machining, for example, NC machining using a ball end mill. Although the concave material is not particularly limited, synthetic wood having good processability, a resin such as an epoxy resin or an acrylic resin, or a metal such as an aluminum alloy or steel can be preferably used.
[0026]
The concave portions may be formed at a time on the mold material, but as shown in FIG. 8A, a set of divided concave molds 61 corresponding to each of the shapes obtained by dividing the fine convex portion into a plurality of portions. It is preferable to manufacture the concave mold 62 by assembling the one set of divided concave molds 61. This is because, according to such a method, it is possible to produce the concave mold 62 corresponding to the convex member 63 having the sharp corner portion 63a that is difficult to be formed at a time.
[0027]
(2) Production of convex member
  Next, as shown in FIG. 8B, the same shape as the fine convex portion is obtained by casting the mold material into the concave mold 62 and inverting it.Or a shape that approximates the surface of the fine convexThe convex member 63 is produced. As the mold material cast into the concave mold 62, for example, wax, epoxy resin (thermosetting type), low melting point metal (melting point of about 100 ° C. or less), etc. can be used. In order to easily follow the curved shape of the tire), it is preferable to use an elastomer.
[0028]
The tire is composed of a curved surface having a constant curvature in the diameter direction and the width direction, and may have a different curvature for each part, so there are special circumstances such as the convex member being small enough to ignore the curvature of the original surface. As long as there is not, as shown to Fig.9 (a), the convex member 73 must also be produced in the shape which has a curvature. However, in such a method, the manufacturing process of the concave mold 72 is required. On the other hand, when the shapes of the original mold 77 and the convex member 73 are not matched, a gap is generated in the contact surface between the two, and a repairing process is required separately. The problem of becoming.
[0029]
Since the elastomer has stretchability and flexibility, even when the concave member 82 is produced by approximating the convex member 83 in a plan view as shown in FIG. It is easy to follow the curved surface shape and can be absorbed if there is some dimensional variation. Therefore, compared with the case where the convex member is formed of a material that does not have elasticity and flexibility, the number of handling steps can be further reduced, and the finished quality can be improved.
[0030]
The “elastomer” referred to in the present specification includes a rubber material having both elasticity and flexibility, and polysulfide rubber, silicone rubber, and polyurethane material having appropriate flexibility and tear strength are particularly preferable. .
[0031]
(3) Prototype production
Finally, the above-mentioned convex member is adhered to a desired location on the surface of the prototype to obtain a tire prototype having fine convex portions. For example, in the case of a vent groove, on the outer edge of each block defined by the original thick groove, in the case of material escape, a location corresponding to the vicinity of the contact surface between the upper mold and the lower mold of the tire mold A convex member is pasted on.
[0032]
The method for attaching the convex member is not particularly limited as long as it can withstand mold reversal, and examples thereof include adhesion using an epoxy-based or cyanoacrylate-based instantaneous adhesive or the like.
[0033]
  The prototype or its inverted type is manufactured as one set of upper and lower integral division types divided into 7 to 11 in the tire circumferential direction and / or one set of upper and lower division types divided into two in the tire width direction, and finallyInverted mold obtained by inverting the prototype twiceIn many cases, the mold is cast by assembling the ring into a ring shape. Therefore, in this specification, “original” and “inverted” include these divided types.
[0034]
The prototype produced as described above is used for casting a mold.
For example, by manufacturing a prototype by the above-described prototype manufacturing method, producing a second reversal mold from the prototype via the first reversal mold, casting a metal melt into the second reversal mold, and reversing the fine recesses Can be obtained.
[0035]
(4) Mold production
  The mold isObtained by inverting the prototype twiceIt can be manufactured by casting a molten metal into a mold. FIG. 10 is a process diagram showing an example of a method of casting a molten metal into a vertically divided mold that is one embodiment of a mold. First, a first reversal mold 92 having the same shape as the mold is produced by casting a first reversal mold material into the master 91. As the first inversion type material, for example, elastic rubber such as silicone rubber and polysulfide rubber can be used.
[0036]
  Next, a second reversal mold 93 having the same shape as that of the original 91 is produced by casting a second reversal mold material into the first reversal mold 92. As the second inversion type material, for example, a non-foamed gypsum, a ceramic mold material using ethyl silicate as a binder, or the like can be used..
[0037]
Finally, the molten metal 96 is cast into the second reversal mold 93. At this time, the above-described vertically integrated split type and / or vertically split type are cut into a predetermined shape 94 and then assembled into a ring shape 95 for casting. After casting, a necessary part is cut out to obtain an upper and lower split mold (mold) 100. The upper and lower split mold 100 is used in a state in which the upper mold and the lower mold are matched at the time of tire molding.
Usually, aluminum alloys such as AC4F, AC4C, AC4D, and AC7A are generally used as the mold material, but cast irons and cast steels such as FCD600, SUS420J2, S50C, and SKD61 are preferably used to ensure the strength.
[0038]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.
[0039]
In the following examples and comparative examples, a mold for molding a tire having a maximum outer diameter of 903 mm and a total contact surface width of 324 mm was used. FIG. 11 shows a schematic shape of the prototype (or mold) and the mold.
The original mold and its inverted mold are manufactured as a set of upper and lower divided molds divided into 12 parts in the tire circumferential direction and further divided into two parts in the tire width direction. We decided to use it for the manufacture of
[0040]
(Example 1-1)
In Example 1-1, “material escape” was formed in the lower mold of the upper and lower split molds by the method (casting) of the present invention. The formation site was a portion 113 corresponding to the tire outer peripheral side on the contact surface with the upper mold as shown in FIG.
The material relief 110a has a minute recess having a semicircular cross section with a radius of 3 mm, and an interval between the outer edge shape of the lower mold 110 and the outer edge shape of the lower mold 110 is 1.5 mm (tolerance ± 0.3 mm). The goal was to form so that
[0041]
In the portion 112 corresponding to the tire center side on the contact surface with the upper mold shown in FIG. 12, a material relief 110b was formed directly on the mold by NC processing using a ball end mill. This is also a fine recess having a semicircular cross section with a radius of 3 mm, but formed in an arc shape concentric with the outer diameter of the tire.
[0042]
(1) Production of concave mold
As shown in FIG. 1, a concave mold 4 having a concave portion 3 having the same shape as the fine concave portion 2 to be formed in the mold 1 was produced. A concave 3 having a semicircular cross section with a radius of 3 mm was formed on a block of synthetic wood (a mixture of epoxy resin and wood chip) by NC processing using a ball end mill, and a concave mold 4 was produced.
[0043]
(2) Production of convex member
By casting epoxy resin into the concave mold 4 and inverting it, a convex member 5 having the same shape as that of the fine convex portion, specifically, a bar shape with a semicircular cross section having a radius of 3 mm was produced.
[0044]
(3) Prototype production
The convex member 5 was attached to a portion corresponding to the tire outer periphery side of the prototype 6 made of synthetic wood with a cyanoacrylate-based instantaneous adhesive.
[0045]
(4) Mold production
A first reversal mold 7 is produced by casting polysulfide rubber (trade name: FMC201, manufactured by Smooth-on Co., Ltd.) on the original mold 6 to which the convex member 5 is adhered. Name: G-6, manufactured by Noritake Company Limited) and a mass ratio of water of 100: 55 was cast to prepare a second inversion mold 8.
[0046]
By casting and reversing the molten metal of AC4F aluminum alloy which consists of Si: 7 mass%, Cu: 0.8 mass%, Mg: 0.4 mass%, and the balance which consists of Al in the said 2nd inversion type | mold 8, it is a micro recessed part. A mold 1 with 2 was obtained. Finally, the material relief on the tire center side was directly formed in the mold 1 by NC processing using a ball end mill.
As a result, the material clearance on the tire outer peripheral side formed by the method of the present invention (casting) was within the range of 1.5 mm ± 0.3 mm from the outer edge shape of the tire molding space. That is, a material escape with high shape accuracy can be formed easily and beautifully, and a good result was shown.
[0047]
(Comparative Example 1-1)
In Comparative Example 1-1, an attempt was made to form a material relief on the tire outer peripheral side by a method of forming a fine convex portion on a prototype by machining. However, as shown in FIG. 13 (a), the tool 116 is in contact with the surface (design surface) of the original 115 and does not reach the portion 117 to be processed, so that the fine convex portion 118 cannot be formed.
[0048]
(Comparative Example 1-2)
In Comparative Example 1-2, an attempt was made to manufacture the mold 1 having the same shape as that of Example 1-1. However, the material escape 2 on the outer peripheral side of the tire was formed by a method of forming fine concave portions directly on the mold by NC processing using a ball end mill. Other steps were performed according to Example 1-1.
As a result, the thickness of the cut-off portion (gap between the material escape and the tire molding space) becomes 1.5 ± 0.5 mm due to the distortion caused by the casting shrinkage of the mold, and the tolerance (1.5 ± 0.3 mm). That is, there was a problem in terms of shape accuracy.
[0049]
(Example 2-1)
In Example 2-1, a “vent groove” was formed by the method (casting) of the present invention. The formation part was a part corresponding to a tire ground contact surface of a vertically divided type.
In the vent groove, a fine recess having a semicircular cross section with a radius of 3 mm was formed in a pseudo-frame shape along the side end portion of the bone of the mold.
[0050]
In Example 2-1, a tire having a structure in which three types of pitches 1 to 3 are arranged as shown in FIG. 14 was used. Therefore, as the prototypes to which the convex members are to be attached, there are the prototype A having the pitch arrangement 2, 1, 2, 2, and the prototype B having 2, 1, 1, 2, 2, 3, 2, 2, 2. Four types of prototype D having prototype C, 2, 3, 3, and 2 were prepared. Finally, a template (second inversion type) prepared from the prototypes A ′ to D ′ with the convex members attached to the prototypes A to D is appropriately cut into a ring shape having the arrangement shown in FIG. Used for mold production.
[0051]
Note that pitches 1 to 3 have three types of rectangular blocks on the original surface having a curved surface shape of R = 1075 mm, but the three types of blocks have different shapes for each pitch. . For example, at pitch 1, three types of a (89 mm × 45 mm), b (81 mm × 49 mm), and c (76 mm × 35 mm) were used.
[0052]
(1) Production of concave mold
A concave mold having a concave shape that is developed by approximating a fine concave section to be formed on a mold in a plane was produced (note that the concave mold produced nine types corresponding to each of three types of blocks on the original surface at pitches 1 to 3. did).
According to FIG. 8, a concave portion having a semicircular cross section with a radius of 0.5 mm is formed in a mold material 65 of synthetic wood (a mixture of epoxy resin and wood chip) by NC processing using a ball end mill as the tool 64. Thus, a set of divided concave molds 61 was produced, and a concave mold 62 was produced by combining them.
[0053]
(2) Production of convex member
Silicone rubber (trade name: TSE350, manufactured by Toshiba Silicone Co., Ltd.), which is an elastomer, is cast into the concave mold 62, and the back surface shape is imparted by the flat back cover 66 and inverted, so that the fine convex portion is developed in a plane approximation. A convex member 63 having a shape, specifically a rod-like body having a semicircular cross section with a radius of 0.5 mm, formed in a pseudo-frame shape was produced.
[0054]
(3) Prototype production
The convex member 63 was attached to the portion corresponding to the tire ground contact surface of the prototypes A to D made of synthetic wood, specifically, on the block 67 of each pitch design with a cyanoacrylate instantaneous adhesive. At this time, there was a part where an error of about ± 0.2 mm was caused in the developed dimension of the block 67 and the convex member 63, but it was possible to absorb it by the stretchability of the convex member 63.
[0055]
(4) Mold production
A first reversal mold is produced by casting polysulfide rubber (trade name: FMC201, manufactured by Smooth-on Co., Ltd.) on the original molds A ′ to D ′ to which the convex members are adhered, and then a non-foamed gypsum ( Product name: G-6, manufactured by Noritake Company Limited) and a mass ratio of water of 100: 55 were cast to prepare a second inversion type.
[0056]
The second inversion mold is appropriately cut and assembled into a ring shape having the arrangement shown in FIG. 14. Si: 7 mass%, Cu: 0.8 mass%, Mg: 0.4 mass%, and the balance is made of Al. By casting a molten metal of AC4F aluminum alloy and inverting it, a mold having fine recesses was obtained. As a result, the appearance quality was beautiful and a good mold could be created.
[0057]
(Comparative Example 2-1)
Also in Comparative Example 2-1, a mold was manufactured by a method according to Example 2-1.
However, similarly to FIG. 9A, a concave mold was produced in a shape having the same curvature as the original mold. As a result, the number of steps for manufacturing the concave mold was 1.5 times. That is, the production efficiency has decreased.
[0058]
(Comparative Example 2-2)
Also in Comparative Example 2-2, a mold was manufactured by a method according to Example 2-1.
However, the convex member was not attached to the original mold, and an attempt was made to form a vent groove by a method of directly forming a fine concave portion by NC processing using a ball end mill on the manufactured mold. However, as shown in FIG. 13B, the tool 126 is in contact with the bone 125a of the mold 125 and does not reach the portion 127 to be processed, so that the fine recess 128 cannot be formed.
[0059]
【The invention's effect】
  Tire of the present inventionMoldThe manufacturing method is the same shape as the fine convex part by casting the mold material into a concave mold prepared by machining in advance and inverting it.Or a shape that approximates the surface of the fine convexSince the convex member is manufactured and the convex member is adhered to the surface of the original mold, a tire mold having fine and complicated concave portions such as vent grooves and material escapes can be obtained with high accuracy and high production efficiency (that is, (Easy and low cost).
[0060]
  In addition, the present inventionMoldAccording to this manufacturing method, a minute and complicated convex shape can be formed relatively easily, so that not only vent grooves and material escapes, but also, for example, putting a manufacturer's logo mark on the tire surface, tire surface performance and aesthetics. It is possible to form a convex shape for improving the property. Therefore, it becomes possible to cope with the complicated design of the tire surface, which contributes to improvement of performance.
[Brief description of the drawings]
FIG. 1 is a process diagram showing a manufacturing process of a prototype and a mold using the present invention.
FIG. 2 is a schematic view showing types of grooves provided in a tire.
FIGS. 3A and 3B are explanatory views showing an example of a vent groove, where FIG. 3A is a top view and FIG. 3B is a cross-sectional view along A-A ′.
FIG. 4 is a process diagram showing an example of compression molding of a tire.
FIG. 5 is a process diagram for explaining a function of material escape.
6A and 6B are explanatory views showing a method for forming a vent groove, wherein FIG. 6A is a top view, and FIGS. 6B and 6C are cross-sectional views taken along line A-A ′.
FIG. 7 is a schematic perspective view showing a method for forming a vent groove.
[Fig. 8] of the present inventionMoldIt is process drawing (a) which shows one embodiment of the manufacturing method of (a), (b), (c).
FIG. 9Mold of the present inventionIt is process drawing which shows the embodiment of this manufacturing method, Comprising: (a) shows the example which made the concave shape the shape which has a curvature, (b) shows the example which comprised the convex member with the elastomer.
FIG. 10 is a process diagram showing one embodiment of a mold manufacturing method.
FIG. 11 is a schematic explanatory diagram showing shapes of a prototype (or a mold) and a mold in Examples and Comparative Examples.
FIG. 12 is a schematic explanatory view showing a material escape formation portion of Example 1-1.
FIGS. 13A and 13B are schematic explanatory views showing a manufacturing process of a prototype or a mold, where FIG. 13A shows a manufacturing process of Comparative Example 1-1, and FIG. 13B shows a manufacturing process of Comparative Example 2-2.
FIG. 14 is an explanatory diagram showing a pitch arrangement of tires of Example 2-1.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Mold, 2 ... Fine recessed part (material escape), 3 ... Recessed part, 4 ... Recessed type, 5 ... Convex member, 6 ... Original mold, 7 ... 1st inversion type, 8 ... 2nd inversion type, 21 ... Tire, 22 , 23 ... thick groove, 24 ... narrow groove (sipe), 31 ... vent groove, 32 ... bone, 33 ... vent hole, 34 ... green tire, 35 ... mold, 36 ... closed space, 37 ... bubble defect (bear) 41 ... Material escape, 42 ... Upper die (42a ... contact surface), 43 ... Lower die (43a ... contact surface), 44 ... Excess material, 45 ... Green tire, 51 ... Block (51a ... Sharp corner) ), 52 ... Installation groove, 53, 54, 55, 56 ... Piece, 61 ... Divided concave, 62 ... Concave, 63 ... Convex member (63a ... Sharp corner), 64 ... Tool, 65 ... Mold material, 66 ... Back cover, 67 ... prototype, 72 ... concave, 73 ... convex member, 77 ... prototype, 78 ... Lid, 82 ... concave, 83 ... convex member, 87 ... prototype, 88 ... back lid, 91 ... prototype, 92 ... first inverted type, 93 ... second inverted type, 94 ... predetermined shape, 95 ... ring shape, 96 ... Molten metal, 97 ... Cast frame, 98 ... Backing material, 99 ... Surface plate, 100 ... Upper and lower split mold (mold), 110 ... Lower mold (110a, 110b ... Material escape), 111 ... Tire molding space, 112 ... A portion corresponding to the tire center side, 113 ... a portion corresponding to the tire outer periphery side, 115 ... a prototype, 116 ... a tool, 117 ... a portion to be processed, 118 ... a fine convex portion, 125 ... a mold (125a ... bone), 126 ... tools, 127 ... parts to be processed, 128 ... fine recesses, 129 ... vent holes.

Claims (4)

A method for manufacturing a tire mold having a fine recess,
By casting a mold material into a concave mold prepared in advance by machining and inverting, a convex member having the same shape as the fine convex portion for forming the fine concave portion in the tire mold or a plane approximation of the fine convex portion is produced. And
By sticking the convex member to the prototype surface, a tire prototype having the fine convex portion is obtained ,
A second inversion type is produced from the tire prototype via the first inversion type,
A method for manufacturing a tire mold, in which a molten metal is cast into the second reversal mold and reversed to obtain a tire mold having a fine recess. The convex member is a convex member having a sharp corner,
Producing a set of split concave molds corresponding to each of the shapes obtained by dividing the convex member into a plurality at the corner portion ;
The method for manufacturing a tire mold according to claim 1, wherein the concave mold is produced by assembling the one set of divided concave molds . The convex member is a convex member having a shape approximating the fine convex portion in a plane,
The method for manufacturing a tire mold according to claim 1 or 2, wherein the convex member is attached to the surface of the tire prototype so as to follow the curved shape of the tire prototype. The method for manufacturing a tire mold according to claim 2 or 3 , wherein an elastomer is used as a mold material cast into the concave mold.

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