JP2006056066A - Tire manufacturing core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently deal with various fluctuations of the volumes in the respective regions of a green tire regardless of the magnitude of them and to simplify and facilitate the attachment, replacement or the like of a non-compressive elastic material to a rigid member in each of the plurality of segments. <P>SOLUTION: In a tire manufacturing core 1 constituted by assembling a plurality of segments 2a and 2b so as to arrange them in an annular form under a mutual adhesion state and having the outer surface shape corresponding to the inner surface shape of a product tire, the respective segments 2a and 2b are constituted by attaching the non-compressible elastic plug 8, which specifically contributes to the outer surface shape, to each of a plurality of the holes 7 formed to the rigid member 6 in an elastically deformable manner. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

This invention is used in the manufacture of tires, and is an annular tire manufacturing core composed of a plurality of segments, which defines the inner surface of a tire from the formation of a green tire to the end of vulcanization thereof, It relates to a highly rigid core.

  For the purpose of manufacturing tires with high dimensional accuracy, each tire component is assembled on a rigid core to form a green tire having dimensions close to the final dimensions of the product tire, and the tire together with the rigid core For example, Japanese Patent Application Laid-Open No. Sho 62-270308 discloses a conventional technique for accommodating a vulcanization mold and performing vulcanization molding there.

  However, in this prior art in which both the core and the vulcanization mold are made of a rigid material, for example, the volume of the green tire during molding or the volume of the green tire thermally expanded by vulcanization molding is When the volume of the vulcanization space defined by the vulcanization mold becomes larger, for example, the rubber protrudes from the divided surfaces of the vulcanization mold components, and inevitably occurs. There was a problem that the tolerance for such volume fluctuation was small.

  On the other hand, the rigid core is replaced with a flexible membrane as disclosed in Japanese Patent Application Laid-Open No. 7-314573, and the flexible membrane is expanded by the supply of internal pressure. When the subsequent vulcanization is performed, the tolerance during vulcanization molding with respect to the volume fluctuation of the green tire can be sufficiently increased by the deformation of the flexible film.

  However, since the flexible membrane is in an expanded state under the supply of internal pressure, it cannot sufficiently support a large external force, and changes in shape and dimensions due to the external force when molding a green tire. Since there is a problem that the molding accuracy of the green tire cannot be lowered, and the flexible membrane is inseparable from the expansion / contraction deformation mechanism, the mechanism of the flexible membrane structure is complicated and large. There was a problem that it was inconvenient to handle because of forced conversion.

  Therefore, in order to solve such a problem caused by using a flexible membrane as a tire manufacturing core, European Patent Application No. 1262310 discloses a rigid core that forms an annular assembly of a plurality of segments. In the vulcanization of a green tire formed by covering the outer periphery of the crown area with a diaphragm and molding on the diaphragm, the diaphragm is made up of a conventionally known vulcanization bladder by the pressure supplied between the rigid core and the diaphragm. A technique has been proposed in which the crown region of the tire is pressed against the inner surface of the vulcanization mold.

  According to this proposed technology, the molding accuracy of the green tire can be improved based on the high external force support capability due to the action of the rigid core, and the core can be removed under a simple and compact structure. In addition to facilitating rotation, the volume of the green tire can be effectively absorbed by making the diaphragm function like a bladder.

  However, in such a proposed technology, the rigid core is disassembled into segments from the vulcanized product tire, and then the diaphragm is airtightly reattached every time the segments are assembled into an annular shape. In addition to the problem that the work process and the number of man-hours are unavoidable, the diaphragm is disposed only in the area corresponding to the crown area of the tire. In the corresponding region, there is a problem that the volume fluctuation of the raw tire cannot be effectively absorbed.

  Therefore, the applicant firstly improved the molding accuracy of the green tire sufficiently without the need for a process for removing and attaching the diaphragm in order to solve such problems of the prior art, and the green Japanese Patent Application No. 2003-297543 has proposed a small tire manufacturing core having a simple structure capable of allowing a large volume fluctuation regardless of the part of the tire.

  The tire manufacturing core is formed by assembling a plurality of segments in an annular shape under close contact with each other, and having an outer surface shape corresponding to the inner surface shape of the product tire. In addition, an incompressible elastic material such as rubber or elastomer is disposed on the outer surface of the rigid core in a layered manner by fixing, fixing, etc. It is configured by providing a plurality of escape recesses for the elastic material.

According to this, in the molding of the green tire on the outer peripheral side of the core, the external force exerted on the core by the tire constituent member, the stitching roll, etc. does not change the rigid core material, and preferably the Young's modulus is 1 ×. Since it will be fully supported by both the layered elastic material of 10 ⁸ to 1 × 10 ¹⁰ N / m ² and the core itself will not undergo substantial changes in shape and dimensions, green tire molding accuracy Can always be as high as expected.

  When the green tire molded on the core is accommodated in the vulcanization mold together with the core and the tire is vulcanized, the volume of the green tire is larger than the volume of the vulcanization space. In this case, the tire causes deformation of the layered elastic material provided by being fixed or fixed to each rigid core material into the escape recess based on the pressing force acting on the tire from the vulcanization mold. . As a result, the volume of vulcanization space defined by the core and the inner surface of the vulcanization mold is substantially increased. The protrusion is effectively suppressed and vulcanization molding is performed as expected.

In addition, each layered elastic material here can be fixed to the core material with local male-female fitting or other joints or mechanical connections at a plurality of locations with respect to the rigid core material. The elastic material fixed or fixed in this way is always integrated with the rigid core regardless of whether the core is disassembled or assembled. Can be performed easily and quickly without the addition of a special process, and the core structure can be simplified and simplified, and the entire core can be minimized.
JP-A-62-270308 JP-A-6-314573 European Patent Application No. 1262310

  This invention relates to the improvement of the above invention according to the applicant's previous proposal, and of course, it is possible to sufficiently deal with various variations in the volume at each part of the green tire, regardless of the amount of it, It is an object of the present invention to provide a tire manufacturing core in which attachment or replacement of an incompressible elastic material to a rigid member is simple and easy in each of a plurality of segments.

  The tire manufacturing core according to the present invention is formed by assembling a plurality of arc-shaped segments in an annular shape under close contact with each other, as in the previously proposed technique. The non-compressible elastic plug that contributes to the identification of the outer surface shape can be elastically deformed in a plurality of depressions or holes formed on the entire rigid segment of each segment. It is constituted by being attached to.

  Here, the surface of the elastic plug may be positioned in the same plane as the curved surface forming the surface of the rigid member, or may be positioned so as to protrude from the curved surface of the rigid member.

  Here, the Young's modulus of the elastic plug is preferably 1.5 to 8.0 MPa, and more preferably 3.0 to 6.0 MPa.

  In this tire manufacturing core, the elastic plugs can be attached to and removed from each segment very easily, and when molding a green tire on its outer surface, this is the same as the proposed technology. Since the external force exerted on the core by the tire constituent member, stitching roll, etc. is sufficiently supported by the rigid member and the elastic plug that does not change in volume, the core itself does not change in shape and dimensions. The molding accuracy of the green tire can be secured sufficiently high.

  Then, when the green tire molded on the core is inserted into the vulcanization mold together with the core and vulcanized, the molding volume or thermal expansion volume of the green tire is the vulcanization molding space, that is, the cavity. When larger or larger than the volume, the tire can be added by elastically deforming the elastic plug in the recess or hole, regardless of the site, resulting in a substantial increase in cavity volume. It is possible to effectively prevent excessive rubber from protruding from the divided surface of the sulfur mold and the like, regardless of the excessive amount of rubber, and always perform proper vulcanization molding.

In this case, if a plurality of depressions or holes are formed evenly on the development surface of the rigid member, the excess volume of the tire can be dispersed and absorbed evenly over the whole.
On the other hand, if the number of hollows or holes, the size, etc. are increased or the elastic modulus of the elastic plug is reduced at the part corresponding to the tread part where the total thickness of the green tire is particularly thick, Including the influence of the thermal expansion of the green tire at the time of molding, it is possible to achieve dispersion absorption according to the tire volume distribution.

  By the way, when the vulcanization molding is performed on the green tire in this way, when the volume of the cavity is selected in advance as a reference volume, for example, -1% of a predetermined volume of the green tire, the actuality of the molded green tire is reduced. Even if the volume is insufficient by 1% with respect to the predetermined volume, a sufficiently appropriate vulcanization molding can be performed, and according to this, the negative side volume fluctuation of the green tire can be effectively absorbed. Can do.

  Here, when the surface of the elastic plug is positioned in the same plane as the curved surface of the rigid member, for example, when the volume of the green tire is insufficient to a predetermined volume, the inner shape of the product tire is sufficiently smooth. On the other hand, when the surface of the elastic plug is positioned slightly protruding from the curved surface of the rigid member, for example, when the volume of the green tire becomes excessive, the elastic plug The inner shape of the product tire can be made sufficiently smooth based on the deformation in the pushing direction.

  As described above, the elastic plug has a Young's modulus of 1.5 to 8.0 MPa, particularly 3.0 to 6.0 MPa. It is preferable in order to support and to exert a resistance against the vulcanization pressure at the time of vulcanization.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional perspective view showing an embodiment of the present invention. A tire manufacturing core 1 shown here has a total of 10 large and small segments 2a and 2b aligned in an annular shape under close contact with each other. The assembled state of the ten segments 2a and 2b is, for example, a pair of rings that engage with all of them simultaneously from the inner peripheral side of the segments 2a and 2b, from the upper and lower sides in the figure. 3 and 4 can be maintained by being interconnected by connecting means 5 arranged at intervals in the circumferential direction.

  Here, the large segment 2a has a generally fan-shaped planar contour shape in which the circumferential length gradually increases outward in the radial direction, as shown in FIG. In addition, the small segment 2b has a shape in which the circumferential length gradually decreases outward in the radial direction or can be constant, and is present in a product tire, for example. The core 1 is disassembled by releasing the connecting means 5 and removing the respective rings 3 and 4 from the segments 2a and 2b. Then, first, all of the small segments 2b are extracted radially inward in the required order. From the extraction position, for example, it can be taken out upward, and then all of the large segments 2b can be taken out in the required order and also in the radial direction and taken out upward.

  On the other hand, in the assembly operation of the core 1, each small segment 2b is fitted between the large segments 2a arranged in advance in a predetermined position by moving outward in the radial direction, and then the segments 2a and 2b are fitted. This can be done by engaging the rings 3, 4 and operating the connecting means 5.

By the way, here, as shown in FIG. 2B by taking the large segment 2a as an example of the enlarged cross-sectional view in the width direction, each of the segments 2a and 2b is inserted into the rigid member 6 in the thickness direction. Each of the holes 7 is formed with an elastic plug 8 made of an incompressible elastic material such as rubber or elastomer. More preferably, the Young's modulus is 3.0 to 6.0 MPa. The elastic plug 8 in the range is prevented from coming off, for example, by engaging the return 8a provided at the tip of the elastic plug 8 with the segment inner surface.
Thus, here, the elastic plug 8 can be attached to the rigid member 6 as well as removed and replaced easily and easily.

  In this case, as illustrated in a perspective view in FIG. 3A, the plurality of holes 7 can be uniformly formed of the same size over the entire rigid member, for example, the rigid member 6. It is also possible to increase the arrangement density of the holes 7 and / or increase the hole size in the crown region.

  The insertion of the elastic plugs into the holes formed in this way is to place the surface of each elastic plug 8 in the same plane as the curved surface of the rigid member 6 as illustrated in FIG. In addition, the plug surface may be positioned so as to protrude from the curved surface of the rigid member, preferably in a curved shape.

  When a green tire is molded on the tire manufacturing core 1 configured as described above, the green tire GT normally deforms the elastic plug 7 as shown in the partial width direction sectional view of FIG. Without being formed, the core 1 is molded with high accuracy.

  Here, when the green tire GT molded in this way has a predetermined volume somewhat larger than the predetermined vulcanization space volume, for example, it is put into the vulcanization mold together with the core 1. When the vulcanization mold is closed, as shown in the partial cross-sectional view in the partial width direction in FIG. The head portion of the plug 8 is pushed and deformed inwardly of the hole 7, and as a result, the green tire GT can occupy a larger space. Therefore, the green tire GT has a predetermined volume. Even if it becomes larger, the protrusion of the mold component from the divided surface is advantageously prevented, and the vulcanization molding is sufficiently adequately performed.

By the way, in this case, when the predetermined vulcanization space volume is set to be 1% smaller than the predetermined volume of the green tire, for example, the green tire volume has a variation of -1% and the green A sufficiently appropriate vulcanization molding can be applied to the tire.
On the other hand, when the volume of the molded tire is a predetermined one and fluctuates to the + side, the volume fluctuation is sufficiently absorbed by the relief of the internal pressure based on the deformation of each elastic plug 8. This also enables proper vulcanization molding.

  That is, in this case, assuming that the variation of ± 1% of the volume of the green tire with respect to the predetermined volume can be absorbed, the change in the volume occupied in the hole 7 of the total elastic plug 8 at that time is conceptually shown in FIG. As shown.

If these are considered in consideration of the thermal expansion of the green tire, the core and the like, they are shown in a graph in FIG.
For example, as shown in FIG. 7A, each of the core and the green tire heated to 130 ° C. and 80 ° C. by preheating is integrally accommodated and heated in a vulcanization mold heated to 180 ° C. In this case, if the mold and the green tire both reach 180 ° C. which is the heating temperature of the vulcanization mold after 3 minutes from the housing, the increase in the core volume due to thermal expansion and the volume fluctuation during The increase in the volume of the green tire included in advance proceeds as indicated by A and B in FIG. 7B, while the temperature of the vulcanization mold is constant, so the volume of its surrounding space is constant. It becomes.

  Therefore, here, the elastic plug 8 is crushed and deformed in accordance with the thermal expansion of the core and the green tire, thereby causing the inward deformation of the hole 7, thereby showing the plug volume occupied in the hole. As shown in 7 (c), the thermal expansion of the core and the green tire is sufficiently allowed by gradually reducing the temperature.

  Thus, according to the core according to the present invention, the volume fluctuation at the time of molding the green tire can be tolerated to a large degree, and at the time of vulcanization molding of the tire regardless of the volume fluctuation at the time of molding the green tire. The volume increase due to the thermal expansion of can also be sufficiently tolerated.

FIG. 8 is a cross-sectional view showing another arrangement mode of the elastic plug.
This is because, for example, the elastic plug 10 is left in the recess 9 provided in the rigid member 6 with a circular planar contour, and the surface thereof is in the same plane as the curved surface of the rigid member 6. 8 is a stepped bolt in which the head is inserted into the central space 11 of the elastic plug 10. The elastic plug 10 is fastened and fixed to the rigid member 6 via 12 to prevent it from coming off.
Here, the stepped bolt 12 can be tightened with, for example, a hexagonal wrench penetrating the elastic plug 10 by making it a hexagonal socket head bolt.

Further, the embodiment shown in FIG. 8B is obtained by engaging the flange 13 provided in the middle in the vertical direction of the elastic plug 10 with the annular groove formed in the hollow wall, and FIG. In the embodiment shown in FIG. 2, the elastic plug 10 is fixed and secured by engaging a flange 14 provided at the lower end of the elastic plug 10 with an annular groove formed in the hollow wall.
Therefore, also in this case, the elastic plug 10 can be attached to and detached from the rigid member 6 and exchanged very easily.

  Any of the elastic plugs 10 arranged in this way has a central space 11 as a deformation space under a deformation tendency as schematically shown in FIG. 9 with respect to an increase in the vulcanization space internal pressure exceeding a predetermined value. Since the inner pressure can be relieved by deforming inwardly of the recess 9 so as to be crushed, in the vulcanization molding of the green tire GT, they are made to function in the same manner as the elastic plug 8 and the green Variations in the volume of the tire GT during molding and vulcanization molding can be sufficiently absorbed regardless of the amount.

  FIG. 10A is a cross-sectional view showing still another mode of arrangement of the elastic plug, in which the elastic plug 15 is rigidized by the stepped bolt 12 in the same manner as described with reference to FIG. In addition to being fixed to the member 6, the surface of the elastic plug 15 formed in, for example, a spherical shape is positioned so as to protrude from the curved surface of the rigid member 6.

  The rigid member 6 arranged in this manner is capable of increasing the internal pressure of the vulcanization space under the selection of the volume of the central space 11 until, for example, the central space 11 disappears as shown in FIG. The excess pressure can be relieved by elastic deformation in the inner direction of the recess 9.

  Here, the limit deformation amount of the elastic plug 15 in this case can be appropriately specified by selecting the plug volume and the central space volume with respect to the hollow volume. For example, as shown in FIG. In addition to being able to position the plug surface in the same plane as the curved surface of the rigid member 6, the plug surface can also be projected or recessed from the curved surface of the rigid member 6.

It is a section perspective view showing an embodiment of this invention. It is a rough line partial cross section of a core, and the width direction cross section of a segment. It is a perspective view which shows the state before and behind arrangement | positioning of an elastic plug. FIG. 3 is a partial cross-sectional view in the width direction of a core and a green tire. It is a width direction fragmentary sectional view which shows the insertion state in the mold of a green tire. It is a figure which shows notionally the absorption aspect of the volume fluctuation | variation of a green tire by an elastic plug. It is a graph which illustrates the state of change of temperature and volume with respect to vulcanization time. It is principal part sectional drawing which shows the other arrangement | positioning aspect of an elastic plug. It is sectional drawing which illustrates the effect | action of an elastic plug. It is principal part sectional drawing which shows the other arrangement | positioning aspect of an elastic plug.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tire manufacturing core 2a Large segment 2b Small segment 3, 4 Ring 5 Connection means 6 Rigid member 7 Hole 8, 10, 15 Elastic plug 9 Depression 11 Central space 12 Stepped bolt 13, 14 Flange GT Green tire M Vulcanization mold

Claims (4)

A tire manufacturing core having a plurality of segments assembled in an annular shape under close contact with each other, and having an outer surface shape corresponding to an inner surface shape of a product tire,
A tire manufacturing core configured by attaching an incompressible elastic plug, which contributes to the identification of the outer surface shape, to a plurality of depressions or holes formed in a rigid member so that each segment is elastically deformable.   The tire manufacturing core according to claim 1, wherein the surface of the elastic plug is positioned in the same plane as the curved surface of the rigid member.   The tire manufacturing core according to claim 1, wherein a surface of the elastic plug is positioned so as to protrude from a curved surface of the rigid member. The tire manufacturing core according to any one of claims 1 to 3, wherein a Young's modulus of the elastic plug is in a range of 1.5 to 8.0 MPa.

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