JP2005329881A - Support body for runflat tire and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a support body for a runflat tire having a shell member having sufficient weight reduction and high durability. <P>SOLUTION: The support body 16 has an annular shell 26 having two projecting parts 30A and 30B, and the shell 26 has a two-layer lamination structure where an aluminum-based layer 32 and a reinforcing layer 34 are laminated in the thickness direction. The aluminum-based layer 32 is formed of an aluminum alloy, and the reinforcing layer 34 is formed of stainless steel or high-tensile steel having high strength. Thus, the shell strength can be increased comparing with the case of molding from only the aluminum alloy, and the weight can be decreased comparing with the case of molding from only the stainless steel or high-tensile steel. Therefore, when the thicknesses of the aluminum-based layer 32 and the reinforcing layer 34 are set suitably according to the strength and weight required for the shell 26 in run flat travel, the shell 26 having sufficient weight reduction and high durability can be molded comparing with the case where the shell is molded using a single metallic material as a raw material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a support for an annular run-flat tire that is disposed inside a pneumatic tire so that it can travel a considerable distance while the tire is punctured, and a method for manufacturing the same.

  For example, in Patent Document 1, run flat running is possible with a pneumatic tire, that is, even if the tire pressure is punctured and the tire internal pressure becomes approximately 0 atm (gauge pressure), the vehicle runs stably for a certain distance (run flat running). ) (Hereinafter referred to as “run-flat tire”), a support for a run-flat tire made of a metal material such as high-tensile steel or stainless steel, for example, on the rim portion in the tire air chamber. (Hereinafter simply referred to as “support”) is disclosed (core type).

  In addition, as a support used in this type of run-flat tire, there is a support provided with a cylindrical shell and rubber legs that are vulcanized and bonded to both ends of the shell. A shape having two convex portions (double mountain shape) in a radial section of a tire attached to a rim is known. Such a shell is manufactured, for example, through a process including plastic working such as spatula drawing, roll forming, and hydroforming on a metal cylinder made of high-tensile steel or the like as a forming material.

In order to ensure sufficient strength, the shell as described above is practically formed from high-tensile steel or stainless steel as a raw material. There is a disadvantage that the vehicle becomes heavier and the handling and fuel consumption of the vehicle decrease. In order to eliminate these inconveniences, attempts have been made to manufacture shells using lightweight aluminum or aluminum materials such as aluminum alloys.
JP-A-10-297226

  However, when the shell is molded from aluminum, the shell can be significantly lighter than when the shell is molded from high-strength steel or stainless steel, but the strength is high-strength steel or stainless steel. It is inferior to a shell consisting of For this reason, when a shell made of an aluminum material is used for run-flat running, for example, a minute dent or crack may occur near the top of the convex portion due to an impact from the road surface. Such minute dents and cracks do not immediately reduce the safety and runnability of run-flat running, but cause the inability to improve the durability of shells made of aluminum. .

  An object of the present invention is to provide a support for a run-flat tire having a shell member that realizes sufficient weight reduction and high durability in consideration of the above facts, and a method for manufacturing the same.

  In order to achieve the above object, a support for a run flat tire according to claim 1 of the present invention is disposed inside a pneumatic tire, assembled to the rim together with the pneumatic tire, and loaded during run flat running. A ring-shaped support body that has at least two protrusions that protrude radially outward in a radial section, and has an annular shell member that is mounted on the outer peripheral side of the rim, The shell member has a laminated structure in which a plurality of metal layers are laminated along the thickness direction, and adjacent metal layers are formed of different kinds of metal materials.

  In the support for a run-flat tire according to claim 1, the annular shell member formed with the two protrusions is formed by laminating a plurality of metal layers along the thickness direction, and adjacent metal By having a laminated structure in which the layers are formed of different types of metal materials, the shell member can be constituted by a plurality of metal layers having different mechanical properties along the thickness direction. In particular, if a laminated structure of a metal layer made of an aluminum alloy with a low specific gravity and a metal layer made of stainless steel or high strength steel, which has a higher specific gravity but higher strength than aluminum alloy, the strength of the shell member is only aluminum alloy. Thus, the shell member can be increased in weight compared to the case of molding from stainless steel or tensile strength steel alone.

  Therefore, according to the support for the run flat tire according to claim 1, the metal material forming the plurality of metal layers constituting the shell member and the thickness of each metal layer are set to the shell member during the run flat running. If it is appropriately selected according to the required strength and weight, it is possible to form a shell member that achieves sufficient weight reduction and high durability compared to the case where the shell member is formed from a single metal material. Therefore, when run-flat running is performed with a run-flat tire using this shell member, the shell member may suffer from dents and cracks that adversely affect running due to loads such as impact from the road surface over a long period of time. Can be prevented and high maneuverability can be obtained.

  A run-flat tire support according to claim 2 is the run-flat tire support according to claim 1, wherein the shell member has a laminated structure including two or three metal layers. Features.

  The support for a run-flat tire according to claim 3 is the support for the run-flat tire according to claim 2, wherein the shell member having a laminated structure including two metal layers is arranged in the thickness direction. The aluminum base layer, which is the inner metal layer, is formed of an aluminum alloy, and the reinforcing layer, which is a metal layer laminated on the outer side of the aluminum base layer, is formed of either high-tensile steel or stainless alloy. Features.

  The support for a run-flat tire according to claim 4 is the support for the run-flat tire according to claim 2, wherein the shell member having a laminated structure including three metal layers is arranged in the thickness direction. The inner and outer reinforcing layers, which are inner and outer metal layers, are formed of either high-tensile steel or stainless steel alloy, and the aluminum base layer that is a metal layer laminated between these reinforcing layers is an aluminum alloy. It was formed by.

  A method for manufacturing a support for a run-flat tire according to claim 5 is a manufacturing method for manufacturing the support for a run-flat tire according to claim 2, and is any one of high-tensile steel and stainless steel alloy. The first metal tube formed in a cylindrical shape by the above is installed in a forming jig, and the second metal tube formed in a cylindrical shape by an aluminum alloy is superposed on the inner peripheral side of the first metal tube. A first step of installing a metal tube in the forming jig, and inserting a coil on the inner peripheral side of the first and second metal tubes installed in the forming jig, and supplying current to the coil Then, an electromagnetic force is applied to the first and second metal tubes, and the first and second metal tubes have a shape corresponding to the shell member along the molding surface formed on the inner peripheral surface of the molding jig. And plastically deforming the first metal tube and the second metal tube to each other in the second step. , Characterized by having a.

  In the method for manufacturing a support for a run-flat tire according to claim 5, the first metal tube formed in a cylindrical shape by either high-tensile steel or stainless alloy is installed in a forming jig, and this A second metal tube formed into a cylindrical shape with an aluminum alloy in a state of being superimposed on the inner peripheral side of the first metal tube is placed in the forming jig, and a coil is placed in the first and second metal tubes. The shell member having a two-layer structure is formed (electromagnetic forming) by bulging and deforming the first and second metal tubes by the electromagnetic force generated by passing a current through the coil. Since the shell member is formed by electromagnetic forming in this way, the forming time is very short (usually 0.1 seconds or less) compared to other processing methods such as hydroforming, and work hardening during plastic deformation This eliminates the possibility of deformation being hindered. That is, since the deformation of the first and second metal tubes proceeds in the superplastic deformation region where the material can be deformed without being affected by work hardening, the two-layer structure can be formed without causing cracking, bending, or the like. The shell member can be accurately formed into a desired shape.

  As described above, according to the support for a run-flat tire and the method for manufacturing the same according to the present invention, a shell member that is realized with sufficient weight reduction and high durability can be formed.

Hereinafter, a support for a run flat tire according to an embodiment of the present invention, a manufacturing method thereof, and a run flat tire using the support will be described with reference to the drawings.
[First Embodiment]
A support for a run-flat tire according to a first embodiment of the present invention and a manufacturing method thereof will be described with reference to FIGS.

  Here, as shown in FIG. 1, the run flat tire 10 is a tire in which a pneumatic tire 14 and a run flat tire support (hereinafter simply referred to as “support”) 16 are assembled to a rim 12. Say. The rim 12 is a standard rim corresponding to the size of the pneumatic tire 14.

  Here, the standard rim is a rim specified by the Yearbook 2002 version of JATMA (Japan Automobile Tire Association), and the standard air pressure is an air pressure corresponding to the maximum load capacity of the yearbook 2002 version of JATMA (Japan Automobile Tire Association). Yes, the standard load is a load corresponding to the maximum load capacity when a single wheel of Year Book 2002 version of JATMA (Japan Automobile Tire Association) is applied.

  Outside Japan, the load is the maximum load (maximum load capacity) of a single wheel at the applicable size described in the following standard, and the internal pressure is the maximum load (maximum load) of a single wheel described in the following standard. The rim is a standard rim (or “Approved Rim” or “Recommended Rim”) at an applicable size described in the following standards.

  The standards are determined by industry standards that are valid in the region where the tire is produced or used. For example, in the United States, it is “The Tire and Rim Association Inc. Year Book”, and in Europe it is “The European Tire and Rim Technical Organization Standards Manual”.

  As shown in FIG. 1, the pneumatic tire 14 includes a pair of bead portions 18, a toroidal carcass 20 extending over both bead portions 18, and a plurality of (this embodiment) located at the crown portion of the carcass 20. The belt layer 22 of two sheets in the form, and a tread portion 24 formed on the upper portion of the belt layer 22.

  The support body 16 disposed inside the pneumatic tire 14 is formed in an annular shape as a whole, and has a cross-sectional shape as shown in FIG. The support 16 has a metal shell 26 and rubber legs 28 vulcanized and molded at both ends of the shell 26. The pair of leg portions 28 are each assembled to the rim 12 when the support 16 disposed inside the pneumatic tire 14 is assembled to the rim of the pneumatic tire 14.

  As shown in FIGS. 1 and 2, the shell 26 is provided with convex portions 30A and 30B that are convex outward in the radial direction, and a concave portion 30C that is convex inward in the radial direction formed between the convex portions 30A and 30B. Side portions 30D and 30E extending from the convex portions 30A and 30B to the inner peripheral side are formed on the outer side in the width direction (X direction in FIG. 2) of the portions 30A and 30B. Flange portions 30F and 30G extending outward in the substantially tire rotation axis direction are formed at the radially inner end portions (rim side end portions) of the side portions 30D and 30E.

  Note that a plurality of through holes (not shown) penetrating in the thickness direction may be formed in the flange portions 30F and 30G of the shell 26 at a substantially equal pitch along the circumferential direction. As a result, the surface area of the bonded portion with the leg portion 28 in the flange portions 30F and 30G is increased, and an anchor effect is generated by the rubber material filled in the through-hole, so that the leg portion 28 and the flange portions 30F and 30G The connection strength can be greatly increased.

As shown in FIG. 2, the shell 26 has a laminated structure in which an aluminum base layer 32 and a reinforcing layer 34 are laminated along the thickness direction thereof. Here, the aluminum base layer 32 is disposed inside along the thickness direction of the shell 26, and is formed using an aluminum alloy as a material. Examples of the aluminum alloy used as the material of the aluminum base layer 32 include an Al—Mg-based aluminum alloy (for example, JIS designation 5000 series) that can obtain high strength by heat treatment, and an Al—Mg—Si-based aluminum alloy (for example, JIS designation). It is desirable to form any one of 6000 series and Al-Zn-based aluminum alloys (for example, JIS designation 7000 series) as a material. When the aluminum base layer 32 of the shell 26 is formed from an aluminum alloy other than these (for example, JIS names 1100 and 3003), the strength is low, and the thickness of the aluminum base layer 32 is required to ensure the required strength. This is because the weight may increase as compared with the case where the entire shell is formed of high-tensile steel or the like. The reinforcing layer 34 laminated on the outer side of the aluminum base layer 32 is formed of either high-tensile steel or stainless alloy. As a material of the reinforcing layer 34, for example, high-tensile steel having a tensile strength of 50 kgf / mm ² or more, or high-strength stainless steel such as SUS304 is desirable.

  At this time, the thickness of the shell 26 is appropriately set in the range of 0.5 mm to 10 mm according to the type of the pneumatic tire 14, the type of vehicle on which the run-flat tire is mounted, and the like. The dimensional ratio between the thickness TB (see FIG. 2) of the aluminum base layer 32 and the thickness TR (see FIG. 2) of the reinforcing layer 34 in the shell 26 is TR: TB = 0.3: 0.7-0. It is desirable to set within the range of 7: 0.3. That is, when the dimensional ratio of the thickness TR of the reinforcing layer 34 is less than 0.3, the strength of the shell 26 with respect to the impact load is insufficient, and the shell 26 is affected by an impact when overcoming a step or the like during run-flat travel. If the dimensional ratio of the thickness TR of the reinforcing layer 34 is greater than 0.7, cracks and deformation may occur, and even if the aluminum base layer 32 is formed of a low specific gravity aluminum alloy, aluminum This is because the effect of reducing the weight of the shell 26 by using the alloy cannot be obtained sufficiently.

  Then, the manufacturing method of the support body 16 which concerns on this embodiment is demonstrated.

First, a forming apparatus for electromagnetically forming the shell 26 of the support 16 will be described. As shown in FIG. 3, the molding apparatus 50 includes molds 52A and 52B that can be divided along the width direction, and the metal pipe 36 and the metal pipe 38 that are loaded in the molds 52A and 52B. Holding members 56 </ b> A and 56 </ b> B that are respectively held at predetermined positions, a coil 58 inserted into the metal tubes 36 and 38, and an electric circuit 60 for energizing the coil 58 with current. The electric circuit 60 is configured as an equivalent circuit of a so-called impact high current generation circuit, and the electromagnetic force required for processing is controlled by energy E (E = 1/2 × CV ² ) stored in the capacitor 70. It has become.

  The molds 52A and 52B are each formed with a molding surface 62 corresponding to the shape of the shell 26 on the inner peripheral side, and at a predetermined position of these molding surfaces 62, an exhaust gas communicating from the molding surface 62 to the outside is provided. A plurality of hole portions 64 are formed. Here, concave surfaces 62A and 62B having a semicircular cross section corresponding to the two convex portions 30A and 30B in the shell 26 are formed on the molding surface 62 of the molds 52A and 52B, respectively, over a half circumference.

  The electric circuit 60 includes a switch 68, a capacitor 70, and a resistor 72, and the capacitor 70 is charged in advance and connected to the switch 68 so that a high voltage current flows instantaneously.

  Using this molding apparatus 50, the shell 26 is molded as follows.

  First, the molds 52A and 52B of the molding apparatus 50 are divided by moving them radially outward, and a cylindrical metal tube 36 is inserted between the divided molds 52A and 52B. After the cylindrical metal tube 38 is inserted in an overlapped state on the inner peripheral side of 36, the molds 52A and 52B are integrated by moving to the inside in the radial direction. At this time, as shown in FIG. 4A, the lower ends of the metal pipes 36 and 38 are supported by the holding member 56B to prevent the metal pipes 36A and 52B from falling off. At this time, it is desirable that the large-diameter metal tube 36 has as little gap as possible between the inner peripheral surface of the metal tube 36 and the outer peripheral surface of the metal tube 38. For this reason, by inserting a small-diameter metal tube 38 into the inner peripheral side of the large-diameter metal tube 36 before loading the molds 52A and 52B, the inner peripheral surface of the metal tube 36 and the outer peripheral surface of the metal tube 38 are brought together. After the pressure contact state, these metal tubes 36 and 38 may be loaded into the molds 52A and 52B.

  Here, the metal tube 36 on the outer peripheral side is made of either high-tensile steel or stainless alloy, and forms the reinforcing layer 34 in the shell 26 by electromagnetic forming. The inner peripheral metal tube 38 is made of an aluminum alloy, and the aluminum base layer 32 in the shell 26 is formed by electromagnetic forming.

  Subsequently, as shown in FIG. 4B, the upper and lower ends of the metal tubes 36 and 38 are positioned by sliding the holding member 56A of the forming apparatus 50 inward and pressing the upper ends of the metal tubes 36 and 38. At the same time, the movement of the metal tubes 36 and 38 in the molds 52A and 52B is restricted. In this state, when an electric current is passed through the coil 58 by the circuit 60 of the molding apparatus 50, an induced current flows through the metal tubes 36 and 38, and at the same time, the metal tubes 36 and 38 follow Fleming's left-hand rule. Receives a pulse-like force (electromagnetic force). The electromagnetic force acts to bulge and deform the metal tubes 36 and 38 to the outer peripheral side. As a result, the metal pipes 36 and 38 are pressed against the molding surface 62 instantaneously (usually 0.1 seconds or less) by the action of the electromagnetic force, and each of them is plastically deformed along the molding surface 62, as shown in FIG. As shown, it is molded into a predetermined shape.

  At this time, the electromagnetic force acting on the metal tube 36 made of high-strength steel or the like having lower conductivity than the aluminum alloy is considerably weaker than the electromagnetic force acting on the metal tube 38. The metal tube 38 disposed on the inner peripheral side swells by a strong electromagnetic force, and the metal tube 36 is pushed out to the outer peripheral side by the pressure applied from the metal tube 38. It can be plastically deformed until pressed.

  Simultaneously with the plastic deformation by electromagnetic forming as described above, a shocking pressure is applied between the inner peripheral surface of the metal tube 36 and the outer peripheral surface of the metal tube 38. As a result, a phenomenon in which metal atoms diffuse to each other occurs at the interface where the inner peripheral surface of the metal tube 36 and the outer peripheral surface of the metal tube 38 are in contact with each other, and the two metal tubes 36 and 38 are joined by pressure welding. Are integrally formed to form a two-layered shell 26.

  Further, when the metal tubes 36 and 38 are plastically deformed by electromagnetic forming as described above, the air interposed between the metal tube 36 and the molding surfaces 62 of the molds 52A and 52B causes the deformation of the metal tubes 36 and 38 to be instantaneous. Therefore, it is difficult to be discharged to the outside through the gap between the two, but since the holes 64 are formed in the molds 52A and 52B, the metal pipe 36 and the mold 52A, The air intervening with 52B can be smoothly discharged to the outside. Therefore, it can be avoided that air remains between the metal tube 36 and the molding surface 62 during electromagnetic molding, thereby hindering the molding of the shell 26. Further, the shell 26 obtained in this way is instantaneously completed by electromagnetic forming using the metal tubes 36 and 38 as the forming material, so that the metal tubes 36 and 38 undergo work hardening accompanying normal plastic deformation. Since the deformation is completed before, the moldability for the metal tubes 36 and 38 is improved, and the shell 26 can be accurately formed into a predetermined shape. After the shell 26 manufactured by electromagnetic forming is heat-treated as necessary, as shown in FIG. 1, the rubber legs 28 are vulcanized and bonded to the pair of flange portions 30F and 30G, respectively. Thus, the support 16 is obtained.

  In the run flat tire support 16 according to the first embodiment described above, the annular shell 26 in which the two convex portions 30A and 30B are formed includes the aluminum base layer 32 and the reinforcing layer along the thickness direction. 34. The aluminum base layer 32 is formed of an aluminum alloy having a relatively low specific gravity, and the reinforcing layer 34 has a higher specific gravity but higher strength than the aluminum alloy. By forming the stainless steel or the high strength steel having hardness, the strength of the shell can be increased as compared with the case where the shell is formed only from the aluminum alloy, and the weight can be decreased as compared with the case where the shell is formed only from the stainless steel or the tensile strength steel.

  Therefore, according to the support body 16 according to the present embodiment, the thicknesses of the aluminum base layer 32 and the reinforcing layer 34 in the shell 26 are appropriately set according to the strength and weight required for the shell 26 during run-flat running. Then, compared to the case where the shell is formed using a single metal material, the shell 26 having a sufficiently light weight and high durability can be formed. When flat running is performed, it is possible to prevent a dent or a crack that adversely affects running due to a load such as an impact from the road surface on the shell 26 over a long period of time, and high maneuverability can be obtained. .

The shell 26 according to the present embodiment is manufactured by plastic processing the two metal pipes 36 and 38 by electromagnetic forming, and a plurality of metal layers are laminated along the thickness direction. After processing a thin plate-shaped rolled material (laminated material) in which adjacent metal layers are formed of different types of metal materials into a thin cylindrical metal tube, this metal tube is subjected to spatula drawing, roll forming, hydro You may manufacture by shape | molding to a predetermined shape by foam processing etc. In this case, the aluminum base layer constituting the inner peripheral side of the shell 26 may be formed of a titanium alloy other than an aluminum alloy, a magnesium alloy, or the like.
[Second Embodiment]
A support for a run-flat tire according to a second embodiment of the present invention will be described with reference to FIGS. In addition, the same referential mark is attached | subjected to the part which is common in 1st Embodiment, and detailed description is abbreviate | omitted.

The support 80 according to the second embodiment is different from the two-layered shell 26 according to the first embodiment in that the shell 82 extends along the thickness direction as shown in FIGS. 5 and 6. This is a three-layer structure. The shell 82 is configured by laminating an inner reinforcing layer 84, an aluminum base layer 88, and an outer reinforcing layer 86 in order from the inner side. Here, the inner reinforcing layer 84 and the outer reinforcing layer 86 are made of either high-tensile steel or stainless alloy, and the aluminum base layer 88 disposed between the reinforcing layers 84 and 86 is made of an aluminum alloy. As an aluminum alloy used as the material of the aluminum base layer 88, for the same reason as the case of the aluminum base layer 32 according to the first embodiment, an Al—Mg based aluminum alloy (for example, JIS name 5000 series), Al—Mg. It is desirable to form either a Si-based aluminum alloy (for example, JIS designation 6000 series) or an Al—Zn-based aluminum alloy (for example, JIS designation 7000 series) as a material. Further, as the material of the reinforcing layers 84 and 86, for example, high-tensile steel having a tensile strength of 50 kgf / mm ² or more, or high-strength stainless steel such as SUS304 is desirable. However, both the inner reinforcing layer 84 and the outer reinforcing layer 86 may be formed of the same metal material (high-strength steel or stainless steel), and one is formed of high-tensile steel and the other is formed of stainless steel. You may do it.

Here, the thickness of the shell 82 is appropriately set in the range of 0.5 mm to 10 mm according to the type of the pneumatic tire 14, the type of the vehicle on which the run-flat tire is mounted, and the like. Also been substantially equal to the thickness TR _OUT thickness TR _IN and outer reinforcing layer 86 of the inner reinforcing layer 84 in the shell 26, the sum TR' and aluminum base layer 88 thickness of these reinforcing layers 84, 86 The dimensional ratio with respect to the thickness TB ′ is desirably set within a range of TR ′: TB ′ = 0.4: 0.6 to 0.8: 0.2. That is, when the TR ′ dimension ratio is less than 0.4, the strength of the shell 82 with respect to the impact load is insufficient, and the shell 82 is cracked or deformed due to the impact when overcoming a step or the like during run-flat running. In addition, when the dimensional ratio of TR ′ is larger than 0.8, even if the aluminum base layer 88 is formed of a low specific gravity aluminum alloy, the light weight relative to the shell 82 due to the use of the aluminum alloy. This is because a sufficient effect cannot be obtained.

  The shell 82 according to the present embodiment has a thin plate-shaped rolled material (laminated layer) in which a plurality of metal layers are stacked along the thickness direction and adjacent metal layers are formed of different types of metal materials. After the material is processed into a thin cylindrical metal tube, the metal tube is formed into a predetermined shape by a processing method such as spatula drawing, roll forming, or hydroforming. The aluminum base layer 88 may be formed of a light metal material such as a titanium alloy or a magnesium alloy in addition to the aluminum alloy. Further, the shell 82 may be manufactured as a molding material using a laminated material having a laminated structure in which four or more metal layers are laminated along the thickness direction. The shell 82 manufactured in this manner is heat-treated as necessary, and then, as shown in FIG. 5, rubber leg portions 28 are vulcanized and bonded to the pair of flange portions 30F and 30G, respectively. A support 80 is used.

  In the runflat tire support 80 according to the second embodiment described above, the annular shell 82 in which the two convex portions 30A and 30B are formed has an inner reinforcing layer 84 along the thickness direction thereof. The aluminum base layer 88 and the outer reinforcing layer 86 have a three-layer structure in which the aluminum base layer 88 is formed of an aluminum alloy having a relatively low specific gravity, and the reinforcing layers 84 and 86 are made of an aluminum alloy. By forming with stainless steel or tensile strength steel having a higher specific gravity but higher strength, similar to the shell 26 according to the first embodiment, its strength can be increased as compared with the case of molding only from an aluminum alloy, In addition, the weight can be reduced as compared with the case of molding only from stainless steel or tensile strength steel.

  Therefore, also with the support body 80 according to the present embodiment, the thickness of the aluminum base layer 88 and the reinforcing layers 84 and 86 in the shell 82 is appropriately set according to the strength and weight required for the shell 82 during run-flat travel. If set, it is possible to form a shell 82 that achieves sufficient weight reduction and high durability compared to the case of forming a shell using a single metal material as a raw material. When run-flat running is performed, it is possible to prevent dents and cracks that adversely affect running due to loads such as impact from the road surface on the shell 82 for a long period of time, and to obtain high maneuverability. it can.

  In the shell 82, one of the inner reinforcing layer 84 and the outer reinforcing layer 86 can be formed from high-tensile steel, and the other can be formed from stainless steel. For example, the outer reinforcing layer 86 is excellent in rust prevention. Further, it may be formed of stainless steel so that rust is generated on the outer peripheral surface of the shell 82 over a long period of time. Thereby, it can prevent effectively that rust generate | occur | produces in the outer peripheral surface of the shell 82, and the friction with the tread part 24 of the shell 82 and the pneumatic tire 14 increases at the time of run flat driving | running | working.

  In addition, the shells 26 and 82 according to the first and second embodiments of the present invention are punched, drilled, and laser processed into holes for allowing air to flow in the pneumatic tire 10 through the convex portions 30A and 30B. For example, it may be perforated. The reason why the holes are formed in the shells 26 and 82 is mainly as follows. That is, the air chamber inside the pneumatic tire 14 is divided by the support 16 into a radially outer air chamber and a radially inner air chamber. Therefore, when there is no hole in the shells 26 and 82, the air volume of the air chamber that acts to cushion the impact transmitted from the road surface via the tread portion 24 is only the amount of the air chamber on the outside in the radial direction. Ride comfort is reduced. Further, in a (normal) pneumatic tire without the support 16, the air in the air chamber whose temperature has increased during traveling is cooled by coming into contact with the metal rim 12, and is controlled within a predetermined temperature range. However, in the run flat tire 10 in which the support body 16 is disposed inside the pneumatic tire 14, the air in the radially outer air chamber does not come into contact with the rim 12, and thus is not cooled well. There is a possibility that the life of the tire may be reduced due to an increase in temperature. However, if the holes are formed in the shells 26 and 82, the outer air chamber and the inner air chamber communicate with each other with respect to the supports 16 and 80, and the buffering action and the cooling action work well.

  In order to confirm the operation of the support according to the first and second embodiments of the present invention and the manufacturing method thereof described above, the support according to the example of the present invention (hereinafter referred to as “example”) and Comparison (evaluation tests 1 and 2) in terms of weight and impact resistance was performed on a conventional support (hereinafter referred to as “comparative example”).

(Evaluation Test 1)
In Comparative Example 1 of this test, a shell is formed using a JIS6061 aluminum alloy (Al-Mg-Si-based aluminum alloy) as a molding material, and a rubber leg is vulcanized and bonded to the shell to produce a support. did. In Comparative Example 2, a support was manufactured by molding a shell using SUS304 stainless steel as a molding material and vulcanizing and bonding rubber legs to the shell.

  On the other hand, in Examples 1 to 3, a two-layer shell having a base layer formed of an aluminum alloy of JIS6061 and a reinforcing layer formed of stainless steel of SUS304 is formed, and rubber legs are added to the shell. A support was produced by sulfur bonding.

  In Examples 4 to 6, a shell having a three-layer structure in which a base layer is formed of an aluminum alloy of JIS6061 and an inner reinforcing layer and an outer reinforcing layer are formed of stainless steel of SUS304 is formed. A support was produced by vulcanizing and bonding the legs.

  While measuring the shell weight which concerns on the said Comparative Examples 1-2, Examples 1-3, and Examples 4-6, a specific weight is calculated | required, and each support body is each mounted | worn in a pneumatic tire, and the block of 30 mm in height After carrying out an impact test overcoming the step formed in a shape at a traveling speed of 60 km / h, it was observed whether or not a crack occurred in each shell.

  The results of Evaluation Test 1 are shown below (Table 1).

(Evaluation test 2)
In Comparative Examples 1 and 2 of this test, a shell was formed by using a JIS6061 aluminum alloy (Al-Mg-Si aluminum alloy) as a molding material, and rubber legs were vulcanized and bonded to the shell. Manufactured. In Comparative Example 3, after forming a shell using SUS304 stainless steel as a molding material, a support was manufactured by vulcanizing and bonding rubber legs to the shell.

  On the other hand, in Examples 1 and 2, the base layer is formed from the aluminum alloy of JIS6061 and the reinforcing layer is formed from the stainless steel of SUS304, using the processing method by electromagnetic forming described in the first embodiment. A two-layer shell was molded, and rubber legs were vulcanized and bonded to the shell to produce a support.

  The weights of the shells according to Comparative Examples 1 to 3 and Examples 1 and 2 were measured to determine the specific weight, and each support was mounted in a pneumatic tire and formed into a block shape having a height of 50 mm. After conducting an impact test over the step at a traveling speed of 40 km / h, it was observed whether or not a crack occurred in each shell.

  In Example 2, the annular reinforcing layer was formed only in the vicinity of the tops of the pair of convex portions that are most likely to crack in the shell, and the shell was partially reinforced.

  The results of Evaluation Test 2 are shown below (Table 2).

It is sectional drawing at the time of rim mounting | wearing of the pneumatic run flat tire to which the support body which concerns on the 1st Embodiment of this invention was applied. It is a fragmentary perspective view of the shell shown by FIG. It is side surface sectional drawing which shows the structure of the shaping | molding apparatus of the support body which concerns on the 1st Embodiment of this invention. (A), (B), and (C) are explanatory drawings for demonstrating the manufacturing process of the shell which concerns on 1st Embodiment of this invention. It is sectional drawing at the time of rim mounting | wearing of the pneumatic run flat tire to which the support body which concerns on the 2nd Embodiment of this invention was applied. FIG. 6 is a partial perspective view of the shell shown in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Run flat tire 12 Rim 14 Pneumatic tire 16 Support body 26 Shell (shell member)
28 Leg part 32 Aluminum base layer 34 Reinforcement layer 36 Metal pipe 38 Metal pipe 50 Molding device 52A, 52B Mold 80 Support body 82 Shell (shell member)
84 Inner reinforcement layer 86 Outer reinforcement layer 88 Aluminum base layer

Claims (5)

An annular support body disposed inside a pneumatic tire, assembled to a rim together with the pneumatic tire, and capable of supporting a load during run-flat travel,
In the radial cross section, at least two convex portions each projecting radially outward are formed, and an annular shell member mounted on the outer peripheral side of the rim is provided.
The shell member has a laminated structure in which a plurality of metal layers are laminated along a thickness direction thereof, and adjacent metal layers are formed of different kinds of metal materials. Support.   2. The run-flat tire support according to claim 1, wherein the shell member has a laminated structure including two or three metal layers.   The shell member having a laminated structure composed of two metal layers is formed by forming an aluminum base layer, which is an inner metal layer, along the thickness direction with an aluminum alloy, and laminating the outer side of the aluminum base layer. The support for a run-flat tire according to claim 2, wherein the reinforcing layer, which is a layer, is formed of either high-tensile steel or a stainless alloy.   In the shell member having a laminated structure including three metal layers, the inner reinforcing layer and the outer reinforcing layer, which are inner and outer metal layers along the thickness direction, are made of either high-tensile steel or stainless steel alloy, respectively. The support for a run-flat tire according to claim 2, wherein an aluminum base layer, which is a metal layer formed and disposed between the reinforcing layers, is formed of an aluminum alloy. A manufacturing method for manufacturing a support for a run-flat tire according to claim 2,
A first metal tube formed in a cylindrical shape with either high-strength steel or stainless steel alloy is placed in a forming jig, and is superposed on the inner peripheral side of the first metal tube with an aluminum alloy. A first step of installing a cylindrically formed second metal tube in the forming jig;
Inserting a coil on the inner peripheral side of the first and second metal tubes installed in the forming jig, and applying an electric current to the coil to cause an electromagnetic force to act on the first and second metal tubes, The first and second metal tubes are plastically deformed into a shape corresponding to the shell member along the molding surface formed on the inner peripheral surface of the molding jig, and the first metal tube and the second metal tube. And a second step with each other,
A method for producing a support for a run-flat tire, comprising:

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