JP2011031452A - Method for manufacturing retreaded tire, mold for manufacturing retreaded tire and vulcanizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a retreaded tire which does not prolong a time of vulcanization while maintaining existing equipment and does not produce fluctuations as a product, and to provide a mold for manufacturing the retreaded tire and a vulcanizer, suited for the method for manufacturing the retreaded tire. <P>SOLUTION: The method for manufacturing the retreaded tire includes: a process of injecting unvulcanized rubber from the outside of a tire mold 10 to the interior R of a tread molding space formed by an outer surface in the circumferential direction of a casing tire 1 and a tire mold molding surface 20A disposed in the tire mold 10; and a process of vulcanizing the injected unvulcanized rubber. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a retreaded tire, and in particular, a method for manufacturing a retreaded tire by injecting unvulcanized rubber into a circumferential outer surface of a base tire installed in a mold, and use of the method. The present invention also relates to a mold for manufacturing a retread tire and a vulcanizing apparatus including the mold.

  Conventionally, the process of manufacturing retreaded tires is generally the process of manufacturing a base tire that becomes the foundation of the retreaded tire through a buffing process of cutting the tread part of a used tire, and the table after the tread part is cut by the buffing process The method includes a step of forming a new tread portion on the outer circumferential surface (crown portion) of the tire, and is classified into a HOT manufacturing method and a COLD manufacturing method depending on the molding method of the tread portion.

  The HOT manufacturing method is a manufacturing method in which an unvulcanized tire tread (raw tread) is stuck on a crown portion of a base tire and vulcanized in a tire mold to integrate the base tire and the tire tread. The COLD manufacturing method is a method in which a vulcanized or semi-cured tread called precure tread is attached to a crown portion of a base tire via an adhesive layer (cushion rubber) and vulcanized in a vulcanizing can. In this way, the base tire and the precure tread are integrated by the adhesive force of the adhesive layer.

JP 07-246665 A

However, in the former manufacturing method, there is a problem that the tread width of the retreaded tire after vulcanization varies as a result of variations in the shape of the raw tread extruded by the extruder. Due to the property of being stored as a temperature, a decrease in temperature is inevitable, and at the time of vulcanization, it is necessary to first vulcanize after warming the raw tread, so that the time required for vulcanization increases.
In the latter method, a step of applying an adhesive layer is required, and a vulcanized or semi-vulcanized precured tread is wound along the crown portion of the base tire, and the ends are joined together. Therefore, there arises a problem that the appearance of the product is impaired, such as a shift in the tread pattern at the end portion and a step between the base tire and the precure tread in the shoulder portion. Further, in any of the production methods, large equipment such as an extruder and a vulcanizing device for producing the tread itself is required, so that problems arise from the viewpoint of equipment investment.

  Accordingly, the present invention provides a method for manufacturing a retread tire, a mold for manufacturing, and a vulcanizing device that do not extend the vulcanization time while maintaining existing equipment to solve the above-mentioned problems, and that does not cause product variations. The purpose is to provide.

In order to solve the above-described problems, a method for producing a retread tire according to the present invention includes an unvulcanized rubber in a tread molding space formed by a circumferential outer surface of a base tire installed in a tire mold and a tire mold molding surface. And a step of vulcanizing the injected unvulcanized rubber.
According to the present invention, the step of applying an adhesive layer and the joint step are eliminated by injecting unvulcanized rubber into the tread molding space formed by the circumferential outer surface of the tire and the molding surface of the tire. In addition, since the injected unvulcanized rubber has a shape along the molding space in the tread molding space, there is no variation in quality as a retreaded tire after vulcanization.

  In addition, since the unvulcanized rubber is injected from outside the tire mold, it is possible to immediately proceed to the vulcanization process while maintaining the temperature of the injected unvulcanized rubber, thereby shortening the time required for vulcanization. be able to.

  Further, in the step of injecting the unvulcanized rubber, pressure is applied from the inner side in the tire radial direction of the base tire, so that the base tire bulges toward the tire mold molding surface, and the tread molding space extends along the circumferential direction of the base tire. And uniform space. Therefore, the thickness (gauge) of the tread portion formed on the outer circumferential surface of the base tire after completion of vulcanization can be made uniform.

  In addition, the end of the injection hole for injecting unvulcanized rubber on the tire mold molding surface side is provided at a position corresponding to the land portion or circumferential groove of the vulcanized retread tire, so that the inside of the tread molding space The unvulcanized rubber to be injected can be evenly distributed in the circumferential direction of the base tire.

Further, if the unvulcanized rubber is injected until the pressure applied from the inner side in the tire radial direction is the same as the pressure in the tread molding space or the pressure in the tread molding space is higher than the pressure applied from the inner side in the tire radial direction, The unvulcanized rubber can be injected without causing a shape change to the radially outer side or radially inner side of the circumferential outer surface of the base tire, and the unvulcanized rubber injected into the tread molding space It is possible to spread uniformly in the circumferential direction of the base tire.
Therefore, the thickness (gauge) of the tread portion formed on the outer circumferential surface of the base tire after completion of vulcanization can be made uniform.

Further, a mold for producing a retread tire according to the present invention includes a molding surface having a tread pattern and an injection hole for injecting unvulcanized rubber into a circumferential outer surface of a base tire installed in the mold, the injection hole However, since it communicates with the tread molding space formed between the outer circumferential surface of the base tire and the molding surface and the atmosphere, it is possible to immediately inject unvulcanized rubber through the injection hole.
Moreover, since the injected unvulcanized rubber has a shape along the molding space in the tread molding space, there is no variation in quality as a product after vulcanization.

  In addition, if the end of the injection hole on the molding surface side is provided at a position corresponding to the land portion or circumferential groove of the retreaded tire, the unvulcanized rubber injected into the tread molding space can be evenly distributed in the circumferential direction of the base tire. Can be spread.

  Moreover, according to the vulcanizing apparatus provided with the said mold for retread manufacture, a very high quality retread tire can be obtained efficiently in a short time.

  The summary of the invention does not enumerate all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention. Further, the present invention will be described in detail below through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included. It is not necessarily essential to the solution means of the invention, and includes a configuration or process that is selectively adopted.

The whole figure of a vulcanizer. The top view of a sector mold. The expanded sectional view which shows the tread molding space R. The expanded sectional view which shows the tread molding space R (other form). The expanded sectional view which shows an injection molding apparatus.

FIG. 1 is an overall view of a vulcanizing apparatus. A base tire 1 formed by buffing a tread portion of a used tire in a circumferential direction is used as a retread tire manufacturing mold 10 (hereinafter simply referred to as a tire mold). It shows the state installed in.).
The base tire 1 is a tire that is a base of a retread tire, and includes a pair of bead portions 2; 2 and a bead portion 2; A skeleton is formed by a carcass extending in a toroidal shape over substantially the entire region.
The bead portion 2; 2 is made of, for example, a bead core made of a bead wire formed by spirally winding a plurality of steel wires, and nylon, canvas cloth, or rubber sheet wound around the bead core. It consists of a chafer etc.

A plurality of belts 4 positioned on the outer side in the tire radial direction than the carcass are disposed in the crown portion A. The belt 4 is a member that extends in the tire width direction at the crown portion A, and is made of, for example, steel.
In this example, the base tire 1 for producing a retread tire is subjected to a buffing process on condition that at least the belt 4 positioned at the outermost side in the tire radial direction is not exposed or damaged in order to ensure quality. A tread part creation process described later is started on the surface of the crown part A of the base tire 1 (hereinafter referred to as a buffed surface 1A). In other words, the tread portion creation process is performed on the outer circumferential surface of the base tire 1.
An inner liner 6 that holds the inner pressure of the base tire 1 and is in contact with the outer surface of a bladder 71, which will be described later, is located on the innermost side in the crown portion A and both side portions B;

The base tire 1 is placed in the tire mold 10 in a horizontally placed state, that is, so that the tire rotation axis is vertical. The tire mold 10 surrounds the crown portion A and both side portions B; B of the base tire 1 installed therein over the entire circumference in the tire circumferential direction, and is in an unvulcanized state in a fluid state from the outside in the tire mold 10. When the tread rubber is injected, a new tread portion is formed in the crown portion A.
Hereinafter, the tire mold 10 will be described in detail with reference to FIG.

The tire mold 10 is a mold apparatus installed on the lower base 19A, and the lower mold 7 installed on the lower base 19A via a heat insulating material 14 and a platen 15 as heating means. Prepare.
The lower mold 7 is a member that holds one side portion B of the base tire 1, and the molding surface that faces and contacts the one side portion B is a design shape formed on the surface of the side portion B In the state where the base tire 1 is placed on the lower mold 7, the base tire 1 is in close contact with the one side portion B.

Above the lower mold 7, an upper mold 9 that faces the base tire 1 in the width direction is positioned, and the upper mold 9 is held by the upper mold holding portion 8.
The upper mold holding part 8 is an annular plate member, and is attached to the lower surface of the upper base 19B via the heat insulating material 14 and the platen 15 laid on the lower surface of the upper base 19B.
Further, the upper mold holding portion 8 and the upper base 19B are connected to the lifting post 41, and the lifting post 41 moves up and down by a driving source (not shown) to approach or separate from the lower mold 7 positioned below. To do.
The upper base 19 </ b> B includes an outer ring 25 that surrounds a tread mold holding portion 13 described later from the outside in the radial direction. The outer ring 25 includes an inclined surface 25A that gradually decreases in diameter as it goes downward. The inclined surface 25A is a surface parallel to the inclined surface 13B of the tread mold holding part 13 positioned below, and abuts on the inclined surface 13B so as to be slidable in the vertical direction as the upper base 19B is lowered.

The outer ring 25 has a plurality of injection holes 25a to 25e. The injection holes 25a to 25e are through holes extending horizontally from the inclined surface 25A to the outer surface 25B, and in the state where the outer ring 25 is lowered to the lower limit position, the injection holes 13a to 13e and the injection holes described later It communicates with 20a to 20e (see FIG. 3).
Further, the outer ring 25 is provided with a tread side heat source supply path 21 extending in the tire circumferential direction. The tread-side heat source supply passage 21 is a passage for circulating a thermal fluid supplied from a heat source supply means (not shown), and raises the temperature of the sector 20 described later to the vulcanization temperature when the vulcanization process is started. Mechanism.

  The upper mold 9 is engaged with the lower surface of the upper mold holding portion 8 and holds the surface of the other side portion B located on the upper side of the base tire 1. The molding surface of the upper mold 9 has an uneven shape corresponding to the design shape and the like formed on the surface of the other side portion B in the same manner as the lower mold 7, and the base tire 1 is mounted on the lower mold 7. In the placed state, it is in close contact with the other side portion B. The platens 15; 15 that are positioned opposite to each other in the vertical direction with the base tire 1 interposed therebetween are heat sources that mainly heat the lower mold 7 and the upper mold 9, and include a heat source supply pipe (not shown) inside. A heat fluid supplied from a heat source supply means (not shown) is supplied into the supply pipe, and the lower mold 7 and the upper mold 9 are heated.

Between the lower mold 7 and the upper mold 9, a tread mold 12 facing the buffed surface 1A of the base tire 1 is located. The tread mold 12 is an annular body configured by combining, for example, nine arc-shaped sectors 20 divided along the circumferential direction of the base tire 1.
Each sector 20 has a molding surface 20A formed as a surface for molding a tread pattern, and the outer surface 20B engages with the engagement surfaces 13A of a plurality of tread mold holding portions 13 corresponding to the sectors 20 individually. . Details of the molding surface 20A will be described later.
The tread mold holding portion 13 holds the sector 20 by engaging means such as grooves and recesses formed on the engaging surface 13A facing the outer surface 20B, and the inclined surface 13B gradually increases in diameter as the outer surface goes downward. Formed as.
Further, the tread mold holding portion 13 is erected so as to be slidable in a radial direction around the tire rotation axis by a rail 16 laid down below. When the outer ring 25 is lowered to the lower limit position and each tread mold holding portion 13 is reduced in diameter toward the tire rotation axis, each sector 20 moves the buffed surface 1A of the base tire 1 along the tire circumferential direction. It will be in the state surrounded along, ie, a mold-clamping state.

  The tread mold holding part 13 has a plurality of injection holes 13a to 13e. The injection holes 13a to 13e are through-holes extending horizontally from the engagement surface 13A to the inclined surface 13B, and communicate with the injection holes 20a to 20e formed in the sector 20.

As shown in FIG. 1, when the outer ring 25 is lowered to the lower limit position, an annular tread molding space R is formed between the molding surface 20 </ b> A of the sector 20 and the buffing surface 1 </ b> A of the base tire 1. In the tread molding space R, unvulcanized tread rubber is injected from the outside of the tire mold 10 through the injection holes 25a to 25e, the injection holes 13a to 13e, and the injection holes 20a to 20e formed in the sector 20. Is done.
That is, when the outer ring 25 is lowered to the lower limit position, that is, when the tire mold 10 is closed, the injection holes 25a to 25e, the injection holes 13a to 13e, and the injection holes 20a to 20e are formed between the tread molding space R and the atmosphere. The injection hole S communicated with the non-vulcanized rubber is formed in the tread molding space R from the outside. In addition, the hole diameter of the injection hole S is set as a diameter φ10 mm, for example.

  Hereinafter, the injection holes 20a to 20e will be described in detail with reference to FIGS. 2 (a) to 2 (c) and FIG. The injection holes 20a to 20e are through holes extending horizontally from the molding surface 20A of the sector 20 to the outer surface 20B, and open to the molding surface 20A. An opening end P that communicates with the tread molding space R and faces the buff processing surface 1A is provided so as to be located at a predetermined position on the molding surface 20A.

FIG. 2A is a plan view of the molding surface 20A, and the sector 20 in the figure is employed when manufacturing a retread tire having a main groove extending in the tire circumferential direction.
The molding surface 20A includes a plurality of main groove forming convex portions 22 extending in the circumferential direction of the base tire 1 and a plurality of land portion forming concave portions 23 partitioned by the plurality of main groove forming convex portions 22 along the tire width direction. Have. Therefore, when the tread portion is molded by the sector 20 having the molding surface 20A, a tread pattern having a shape reversed from the shape of the molding surface 20A is formed on the tread portion. After vulcanization, the tread portion is formed in the tire circumferential direction. A rehabilitated tire having a plurality of main grooves (rib grooves) extending over the land and a plurality of land portions partitioned along the width direction by the main grooves can be obtained. In the drawing, the opening end P is individually provided so as to correspond to a plurality of land portion forming recesses 23 that form the land portions of the tread portion after vulcanization, and at the center in the width direction of each land portion forming recess 23. Open.

  The molding surface 20A in FIG. 2B is employed in the sector 20 when manufacturing a retread tire having a main groove extending in the circumferential direction and a width direction groove extending inward in the tire width direction. The molding surface 20A is formed by a plurality of zigzag main groove forming convex portions 24 extending in the tire circumferential direction, a plurality of width direction groove forming convex portions 29 extending inward in the tire width direction, and the main groove forming convex portions 24 in the width direction. And a plurality of land portion forming recesses 26 that are divided along the line. Therefore, when the tread portion is molded by the sector 20 having the molding surface 20A, a tread pattern having a shape inverted from the molding surface 20A is formed. After vulcanization, a plurality of tread portions extending in the tire circumferential direction are formed on the tread portion. , A plurality of land portions partitioned in the width direction by a plurality of main grooves, and a retread tire having a groove (lag groove) extending in the tire width direction in the land portion in the vicinity of the side portion B can be obtained. . Also in this example, the opening end P is individually provided so as to correspond to the plurality of land portion forming recesses 26 that form the land portions of the tread portion after vulcanization, and each land portion forming recess 26 is substantially at the center in the width direction. Open at the position of. In this example, the opening end P is smaller than the opening end P in FIG. 2A, but the number of the injection holes S is appropriately determined by the number of land portions partitioned by the circumferential groove of the tire, Of course, the number of the open ends P is also appropriately determined.

The molding surface 20A in FIG. 2C is employed in the sector 20 when manufacturing a retread tire having a main groove extending in the tire circumferential direction and a width direction groove extending over the entire tire width direction. The molding surface 20A includes a plurality of main groove forming convex portions 27 extending in the tire circumferential direction, a plurality of width direction groove forming convex portions 28 extending over the entire tire width direction, the main groove forming convex portions 27, and the width direction grooves. And a plurality of land portion forming recesses 30 partitioned by the forming protrusions 28 in a block shape.
Therefore, when the tread portion is molded by the sector 20 having the molding surface 20A, a tread pattern having a shape inverted from the shape of the molding surface 20A is formed, and the vulcanized tread portion extends in the tire circumferential direction. It is possible to obtain a retread tire having a so-called block pattern land portion defined by a groove and a groove extending in the tire width direction.
Also in this example, the open end P is individually provided so as to correspond to the plurality of land portion forming recesses 30 that form the land portions of the tread portion after vulcanization, and the width direction substantially center of each land portion forming recess 30 Open at the position of. Note that the molding surface 20A is provided with a protrusion or the like for forming a sipe or the like provided for improving drainage in any of the above forms, but the illustration is omitted.

  As described above, the opening end P of the molding surface 20A is a land that is defined by at least a groove in the tire circumferential direction of a retread tire to be manufactured regardless of the shape (tread pattern) of the molding surface 20A. The unvulcanized rubber that is individually provided at a position corresponding to the land portion forming recess 23 (26, 30) that forms the portion and is injected into the tread molding space R can be distributed without excess or deficiency for each land portion. Is possible. In other words, the injection hole S communicates with the tread molding space R formed by the buffing surface 1A of the base tire 1 and the molding surface 20A and the atmosphere, and is the end of the injection hole S on the molding surface 20A side. The opening end P is a structure located in the land part formation recessed part 23 (26, 30) which forms the land part divided by the groove | channel of the tire circumferential direction in the tread part of the retreaded tire used as manufacture object. By adopting a configuration in which the opening end P of the injection hole S is opened at the position, the following extremely remarkable effects can be obtained.

That is, as shown in FIG. 3, the main groove forming convex portions 22 (24, 27) formed on the molding surface 20A protrude from the land portion forming concave portions 23 (26, 30) toward the buff processing surface 1A side of the base tire 1. Because of this shape, the gap X between the end surface of the main groove forming convex portion 22 (24, 27) and the buffed surface 1A is relatively narrow, and the fluidity is poor. However, if the opening end P is formed so as to be positioned for each land portion forming recess 23 (26, 30) forming the land portion of the retreaded tire, the land portion forming recess 23 (26, 26) extending in the tire circumferential direction is formed. It is possible to reliably distribute unvulcanized rubber to 30).
Further, since the gap X having poor fluidity is sandwiched between the plurality of opening ends P formed in the tire width direction, a sufficient amount of unvulcanized rubber is supplied into the gap X. .
Therefore, the unvulcanized rubber injected between the buffed surface 1A of the base tire 1 and the molding surface 20A that is the inner surface of the tire mold 10 can be uniformly distributed, and the quality of the retreaded tire after vulcanization It is possible to significantly reduce the possibility that the variation occurs.
The number and arrangement of the open ends P are not limited to the above example, and a plurality of open ends P may be formed along the tire circumferential direction with respect to one sector 20. Moreover, in the molding surface 20A shown in FIG. 2C, the opening ends P may be individually provided so as to correspond to all the land portion forming recesses 30.
More preferably, if the opening ends P are provided at intervals of, for example, 90 ° or 180 ° for each sector 20 constituting the tread mold 12, the injection completion time can be shortened and a large-scale installation is required. Without unvulcanized rubber can be injected quickly and efficiently.

As shown in FIG. 5, the opening end Q of the injection hole S and the injection hole 63 of the injection molding device 60 are connected to each other via a hollow joint 51.
The injection molding apparatus 60 is generally an extrusion that heats and kneads a diene rubber member such as SBR or BR that composes an unvulcanized tread rubber, a filler such as carbon black or silica, a vulcanizing agent, etc. at a temperature lower than the vulcanization reaction temperature Machine 61, cylinder 65 for storing unvulcanized rubber supplied from extruder 61 while keeping the temperature below the vulcanization reaction temperature, and fluidized unvulcanized tread rubber stored in cylinder 65 for injection hole 63. It is comprised from the plunger 70 extruded to the side.
The cylinder 65 is formed of a cylindrical body, and an injection hole 63 is formed at one end, and a storage space 66 communicating with the injection hole 63 is formed inside. The plunger 70 is a member that injects unvulcanized rubber supplied to the storage space 66 from the injection hole 63, and is stored in the storage space 66 by moving forward from the other end side of the cylinder 65 to the injection hole 63 side. Unvulcanized rubber is injected from the injection hole 63 at a constant pressure.
The joint 51 has a shape branched at one end to be connected to the injection hole 63 and the other end corresponding to the opening end Q of the injection holes S arranged in the tire width direction. Therefore, the unvulcanized rubber injected from the injection molding device 60 is divided into a plurality of land portion forming recesses 23 (26, 30) on the molding surface 20A and injected into the tread molding space R from the opening end P.
In this way, the joint 51 directly connects the opening end Q of the tire mold 10 and the injection hole 63 of the injection molding device 60, and injects unvulcanized rubber generated outside the tire mold into the tread molding space R. With this configuration, since the temperature of the unvulcanized rubber below the vulcanization temperature is not lowered, the unvulcanized rubber injected into the tread molding space R can be vulcanized in a very short time. Become.

As shown in FIGS. 1 and 3, when unvulcanized rubber is injected by the injection molding device 60, an internal pressure is applied to the base tire 1 by the in-tire pressure device 3. The in-tire pressurizing device 3 includes an annular bladder 71 made of an expandable / contractible member. The lower end edge that is opened is held by the lower clamp ring 72, and the upper end edge that is opened is held by the upper clamp ring 73. It is formed in a bag shape having airtightness. The lower clamp ring 72 and the upper clamp ring 73 are attached to a center post 74 and a center rod 75 that can be moved up and down independently of each other, and the center rod 75 extends to extend the bladder 71 in the up-down direction. The tire 1 can be inserted into the tire 1.
In addition, when the bladder 71 is inserted into the base tire 1 as shown in FIG. 1, the lower clamp ring 72 and the upper clamp ring 73 have bead rings 76; 76 that hold the vicinity of the bead portion 2 of the base tire 1. Is attached to the bead ring 76; 76 by attaching a seal member and a lock mechanism (not shown) so that the thermal fluid supplied to the inside of the bladder 71 does not leak to the outside. Note that an inert gas, nitrogen gas, saturated water vapor, or the like is employed as the thermal fluid.

  Thermal fluid is supplied into the bladder 71 from a heat source supply device (not shown) via a thermal fluid supply passage 77 provided in the center post 74. The bladder 71 expands in all directions inside the base tire 1 with the supply of the thermal fluid, and the outer surface of the bladder 71 comes into close contact with the surface of the inner liner 6 of the base tire 1 so that the base tire 1 is moved from the inside to the outside. Press against.

As shown in FIG. 3, when the bladder 71 is inflated, both side portions B; B of the base tire 1 are pressed toward the lower mold 7 and the upper mold 9 by internal pressure and are held immovably in the tire mold 10. The On the other hand, the crown portion A of the base tire 1 slightly expands outward in the tire radial direction, that is, toward the molding surface 20A due to the internal pressure, and the volume of the tread molding space R is reduced. In this state, the unvulcanized tread rubber is injected from the outside, whereby the tread portion having the same shape as the tread molding space R can be formed over the entire circumferential direction of the base tire 1.
Moreover, it is preferable that the internal pressure applied to the bladder 71 is the same as the internal pressure applied when the used tire before the buffing process that is the basis of the base tire 1 is molded. That is, when a green tire is vulcanized to produce a product tire, an apparatus having substantially the same configuration as the tire mold 10 and the tire pressure device 3 according to the present invention is used. If the internal pressure is applied to the base tire 1 with the same internal pressure as the internal pressure, excessive swelling or shortage of the amount of swelling in the tread molding space R of the crown portion A can be prevented. A retread tire having a tread gauge can be obtained. The pressure in this case is, for example, a pressure that is arbitrarily selected and set from 4 kgf / cm ^{2 to} 6 kgf / cm ² .
Further, the air staying between the outer surface of the bladder 71 and the inner surface of the inner liner 6 passes through a fine discharge path that communicates with the outside of the tire mold 10 through a groove formed on the outer surface of the bladder 71. Discharged. Note that the means for applying the internal pressure to the base tire 1 is not limited to the bladder 71, and air may be directly supplied into the base tire 1 without using the bladder 71.

Hereinafter, the manufacturing method of the retreaded tire using the tire mold 10 which consists of the said structure is demonstrated later on. First, the buffed base tire 1 is placed horizontally on the lower mold 7 by a conveying device such as a loader mechanism (not shown), and the center rod 75 is extended so that the bladder 71 is extended in the vertical direction. Later, the bladder 71 is inserted into the base tire 1 by reducing the center rod 75 to a predetermined position in the tire width direction. Then, after attaching the bead ring 76: 76 and a lock mechanism (not shown), the center post 74 is lowered, and the base tire 1 is placed on the lower mold 7 located below.
Next, the upper mold 9 is brought into contact with the other side portion B of the base tire 1 by lowering the elevating post 41. Simultaneously with the lowering of the lifting post 41, the plurality of tread mold holding portions 13 erected on the rail 16 are reduced in diameter in the tire radial direction, and the buffed surface 1A of the base tire 1 is surrounded by the tread mold 12. Become.

  Next, the tire pressing step will be described. High temperature and high pressure thermal fluid is supplied into the bladder 71 inserted in the base tire 1 through a thermal fluid supply passage 77 provided in the center post 74 by a pressurizing means (not shown) to expand the bladder 71. Let The expanded bladder 71 is in close contact with the surface of the inner liner 6 inside the base tire 1, and pressure is applied to the inside of the base tire 1. By applying pressure, both side parts B; B of the base tire 1 are held immovably by the lower mold 7 and the upper mold 9, and the crown part A slightly expands in the direction of the molding surface 20 A of the sector 20. The tread molding space R is formed over the entire circumference in the tire circumferential direction between the buffed surface 1A and the molding surface 20A.

Next, an unvulcanized rubber injection process will be described. First, the injection hole 63 of the injection molding device 60 and the opening ends Q of the plurality of injection holes 25a to 25e (injection holes S) provided in the outer ring 25 are connected via the joint 51.
Next, the unvulcanized rubber supplied from the extruder 61 is injected into the cylinder 65 of the injection molding device 60 from the injection hole 63 by moving the plunger 70 forward.

Here, the injection amount of the unvulcanized rubber is set so that the pressure P1 of the unvulcanized rubber in the tread molding space R is slightly higher than the internal pressure P2 applied to the base tire 1. That is, when the pressure P1 of the unvulcanized rubber in the tread molding space R is lower than the internal pressure P2 applied to the base tire 1, the tread gauge after vulcanization may be thin. In order to secure the tread gauge, the pressure P1 in the tread molding space R is desirably set higher than the internal pressure P2 applied to the base tire 1. More desirably, if the injection amount of the unvulcanized rubber is set so that the pressure P1 of the unvulcanized rubber in the tread molding space R and the internal pressure P2 applied to the base tire 1 are equal to each other, There is an extremely remarkable effect that it is possible to produce a retread tire having the same tread gauge as the product tire.
When unvulcanized rubber is injected into the tread molding space R, the air staying in the tread molding space R is discharged out of the tire mold 10 through a plurality of exhaust holes (not shown) or fine gaps between the plurality of sectors 20. Is done.

  Next, the vulcanization process will be described. After sufficient unvulcanized rubber is injected into the tread molding space R, the vulcanization process is performed. Specifically, by supplying a thermal fluid to the tread side heat source supply path 21, the unvulcanized rubber injected into the tread molding space R is raised to the vulcanization temperature, and is applied to the buffed surface 1 </ b> A of the base tire 1. A tread portion having the same shape as the tread molding space R is formed by being firmly integrated.

  Next, the tire removal process will be described. After completion of vulcanization, the upper mold 9 is separated from the other side portion B by raising the elevating post 41. As the elevating post 41 is raised, the engagement between the inclined surface 25A of the outer ring 25 and the inclined surface 13B of the tread mold holding portion 13 is released, and the tread mold holding portion 13 moves outward along the rail 16 in the tire radial direction. Each sector 20 is peeled off from the tread portion after vulcanization and demolding is completed. Next, after removing the upper bead ring 76, the bladder 71 is set in the extended state, and the bladder 71 is peeled off from the inner liner 6 to complete the manufacture of the retread tire.

Hereinafter, other embodiments according to the present invention will be described. FIG. 4 is a sectional view of a sector 40 according to another embodiment. The molding surface 40A of the sector 40 in this embodiment is different from the above-described configuration in that the opening end P of the injection hole S opens at the tip of the main groove forming convex portion 22 (24, 27).
That is, the opening end P of the injection hole S in this embodiment is individually provided so as to correspond to the plurality of main groove forming convex portions 22 (24, 27) that form the circumferential grooves of the tread portion after vulcanization. The main groove forming convex portions 22 (24, 27) are opened at a position substantially in the center in the width direction.
According to this embodiment, since the opening end P is located at a position corresponding to the gap X having poor fluidity in FIG. 3, the injected unvulcanized rubber is placed in the adjacent land portion forming recess 23 (26, 30). Since it flows so as to wrap around, unvulcanized rubber can be reliably distributed to the land portion forming recesses 23 (26, 30) extending in the tire circumferential direction.
Further, since the open end P exists at a position corresponding to the gap X having poor fluidity, a sufficient amount of unvulcanized rubber is supplied into the gap X.
Therefore, even in this embodiment, the unvulcanized rubber injected between the buffed surface 1A of the base tire 1 and the molding surface 40A that is the inner surface of the tire mold 10 can be evenly distributed, The possibility of variations in the quality of retreaded tires can be significantly reduced.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the said embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made to the above-described embodiment, and it is obvious that such changes and modifications can be included in the technical scope of the present invention. It is clear from the description.

1 tire, 1A buffed surface, 2 bead parts, 7 lower mold,
8 Upper mold holding part, 9 Upper mold, 10 Remolded tire manufacturing mold,
12 tread mold, 13 tread mold holder, 20 sectors,
20A molding surface, 20-20e injection hole, 22 (24, 27) main groove forming convex part,
23 (26, 30) land forming recess, 25 outer ring,
40 sectors, 40A molding surface, 51 joints, 60 injection molding equipment,
63 Injection hole, 71 Bladder, P Open end, R Tread molding space.

Claims (8)

Injecting unvulcanized rubber into the tread molding space formed by the circumferential outer surface of the base tire installed in the tire mold and the tire mold molding surface;
And a step of vulcanizing the unvulcanized rubber.   The method for producing a retread tire according to claim 1, wherein the unvulcanized rubber is injected from outside the tire mold.   The method for producing a retread tire according to claim 1 or 2, wherein, in the step of injecting the unvulcanized rubber, pressure is applied from a tire radial inner side of the base tire. The end portion of the injection hole for injecting the unvulcanized rubber on the tire mold molding surface side,
The method for producing a retread tire according to any one of claims 1 to 3, wherein the vulcanized tire is provided at a position corresponding to a land portion or a circumferential groove of the retread tire after vulcanization.   In the unvulcanized rubber, the pressure applied from the inside in the tire radial direction is equal to the pressure in the tread molding space, or the pressure in the tread molding space is applied from the inside in the tire radial direction. The method for producing a retread tire according to any one of claims 1 to 4, wherein the retread tire is injected until it becomes higher. A mold for manufacturing a retread tire having a molding surface having a tread pattern,
The mold includes an injection hole for injecting unvulcanized rubber on a circumferential outer surface of a base tire installed in the mold, and the injection hole is formed by a tread molding between the peripheral outer surface of the base tire and the molding surface. A mold for manufacturing retreaded tires, which communicates with space and the atmosphere.   The mold for manufacturing a retread tire according to claim 6, wherein an end of the injection hole on the molding surface side is provided at a position corresponding to a land portion or a circumferential groove of the retread tire.   A tire vulcanizing apparatus comprising the mold for manufacturing a retread tire according to claim 6 or 7.

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