JP2005335569A - Manufacturing method and device of support shell for run-flat tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a support member of a run-flat tire realizing sufficient weight reduction and high durability, and having a support shell accurately formed into a prescribed shape. <P>SOLUTION: When manufacturing the support shell, an aluminum material 54 is installed in metallic molds 56A, 56B, the edge part of the aluminum material 54 abuts to the surface of the metallic molds forming grooves or irregularities, coils 58 are inserted into the aluminum material 54, the aluminum material is swollen by electromagnetic force generated by carrying current to the coils 58 to be plastically deformed along a forming face 62 and the drawing of the material is prevented. As a result, the shell member accurately formed into a desired shape can be obtained without generating cracks and bending, etc on the support shell. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a support shell used for a support member for an annular run-flat tire disposed inside a pneumatic tire so that it can travel a considerable distance in a punctured state during tire puncture, and its The present invention relates to a manufacturing apparatus.

  In Patent Document 1, as a tire capable of run-flat running with a pneumatic tire (hereinafter referred to as a run-flat tire), a metal such as high-tensile steel, stainless steel, or the like is provided at a rim portion in the air chamber of the tire. An attachment with a support member made of a material is disclosed.

  The support member includes rubber legs that are vulcanized and bonded to both ends of a support shell formed from a cylindrical material. The support shell is a tire attached to a rim. A two-sided shape is known in the radial cross section. Such a support shell is manufactured through a process including plastic processing such as spatula drawing processing, roll forming processing, hydroforming processing, and the like, using a metal cylinder made of high-strength steel or the like as a forming material. However, the support shell as described above is heavy, and there is an inconvenience that the operability and fuel consumption of the vehicle are reduced.

JP-A-10-297226

  In order to eliminate these inconveniences, attempts have been made to manufacture a support shell using a lightweight aluminum alloy or the like as a material (hereinafter referred to as an aluminum material). In foam molding and roll forming, defects such as cracking of the material are likely to occur, and it is difficult to stably manufacture the support shell.

  In particular, the hydroforming process takes about 2 seconds to process (plastic deformation), so the aluminum material, which is the object of processing, is hardened during deformation due to its properties, and the elongation becomes smaller. There was an inconvenience that cracking occurred.

  However, the inventors of the present application have advanced research and development on manufacturing a support shell by electromagnetic forming (electromagnetic tube forming) using an aluminum alloy as a raw material. According to this electromagnetic forming, the aluminum material can be processed into a desired shape in a very short time (usually within 0.1 seconds), so that the support shell can be formed by deforming the aluminum material in the superplastic deformation region. It has been found that it is possible to effectively prevent the occurrence of cracking and bending due to the effect of work hardening even in a portion where the amount of plastic deformation is large, and a new support shell has already been proposed as Patent Document 2.

Japanese Patent Application No. 2003-392169

  As a method for forming the support shell, the electromagnetic tube expansion molding method is an excellent method as described above, but it is not without problems. That is, when the base tube is plastically processed during electromagnetic tube expansion molding, drawing (retraction) occurs on the molding side of the support shell from both ends in the molding die abutting against the aluminum material, and depending on the shape, it is completed. The shape cannot be obtained.

  In view of the above facts, an object of the present invention is to provide a support shell for a run-flat tire that is accurately molded into a predetermined shape while ensuring light weight and high durability.

  In order to achieve the above object, the present invention is configured as follows. That is, the first is a method of manufacturing a support shell for a run-flat tire, which is a molding die end face that comes into contact with the aluminum material of a molding die that deforms a cylindrical aluminum material into a desired shape. A first step in which the aluminum material is placed in the molding die, and the end of the aluminum material is in contact with and fixed to the end surface of the molding die. The coil is inserted into the inner periphery of the aluminum material installed in the molding die, and an electric current is applied to the coil to cause electromagnetic force to act on the aluminum material. These aluminum materials correspond to the molding die. A support shell for a run-flat tire comprising the second step of plastically deforming into a shape to be formed, and speaking of the support shell, preferably before the second step, the desired material in the aluminum material The outer peripheral side or inner peripheral side of the part It is obtained by adding the step of overlaying the reinforcing ring.

  The second is an apparatus for manufacturing a support shell for a run-flat tire, which is an end surface of a molding die that comes into contact with the aluminum material of a molding die that plastically deforms a cylindrical aluminum material into a desired shape. The manufacturing apparatus is characterized in that a groove and / or unevenness is formed on the aluminum material and drawing at the time of forming the abutting aluminum material is eliminated, and the plastic deformation of the aluminum material is due to electromagnetic tube expansion forming means.

  The present invention provides a method and apparatus for manufacturing a support shell by electromagnetic forming (electromagnetic tube forming) using an aluminum alloy as a raw material, which can be processed into a desired shape in a very short time, and is plastically deformed. Even in the case of a large amount of support shell, it prevents cracking and bending, and when the base tube is plastically processed, it draws from the both end surfaces of the molding die holding the aluminum material to the molding side. It was possible to provide a support shell with no phenomenon.

  Here, the manufacturing method of the support shell for the run flat tire according to the first invention will be mainly described. The aluminum material (and the reinforcing ring) are respectively installed in the molding die, the coil is inserted into the aluminum material, An aluminum material is bulged and deformed (electromagnetic tube forming) by an electromagnetic force generated by passing a current through the coil, and a support shell having at least two convex portions is formed. At this time, by devising the end face of the molding die so that the aluminum material is not drawn during molding, the aluminum material is deformed as expected, and other processing methods such as hydroforming The molding time is very short compared to (usually 0.1 seconds or less), and there is no possibility that deformation is hindered by work hardening during plastic deformation. In other words, since the deformation of the aluminum material proceeds in a superplastic deformation region where the material can be reliably deformed without being affected by work hardening, the support shell is formed into a desired shape without causing cracks or bending. This is what you can do.

  And in the aluminum material, in order to prevent the drawing of the part supported by the contact surface of the molding die at the time of molding, the end of the material is fixed at an early stage during molding, One is to place a groove on the abutment surface of the molding die with the aluminum material (the end groove method), so that it can be caught outside the product at the initial stage of molding, thus preventing drawing. The desired shape can be obtained. The second is to provide unevenness on the surface of the molding die (end unevenness method), which has the same function.

  Here, the effect of the reinforcing ring will be described. Usually, the support shell has at least two protrusions, but since the cylindrical aluminum material is manufactured by electromagnetic forming, the vicinity of the top of the protrusions is deformed (stretched). The amount) is large and the wall thickness is thinner than other parts. For this reason, an aluminum reinforcing ring is superposed on the portion corresponding to the top of the aluminum material, plastically deformed into a shape corresponding to the support shell by electromagnetic forming, and the reinforcing ring is formed by shocking pressure generated by electromagnetic forming. The reinforcing part was formed by pressure bonding to an aluminum material, and the thickness near the top of the convex part was increased, so that the strength could be greatly increased. Such a reinforcing ring may be arranged inside the convex part or arranged outside.

  The aluminum material constituting the support shell is formed by using any one of an Al-Mg-based aluminum alloy, an Al-Mg-Si-based aluminum alloy, and an Al-Zn-based aluminum alloy. It is desirable to use these materials. Specifically, an Al—Mg-based aluminum alloy (for example, JIS designation 5000 series), an Al—Mg—Si-based aluminum alloy (for example, JIS designation 6000 series) and an Al—Zn-based aluminum alloy (for example, JIS designation 7000 series). A support shell having sufficient strength is manufactured by forming a cylinder using any one of the above) as a material and subjecting the cylindrical material to a predetermined heat treatment as necessary.

  The run-flat tire is a carcass formed in a toroid shape between a pair of bead cores, a side rubber layer that is disposed on the outer side in the tire axial direction of the carcass to form a tire side portion, and is disposed on the outer side in the tire radial direction of the carcass. And a tread rubber layer that constitutes a tread portion, and includes a pneumatic tire that is attached to the rim, and a support member that is disposed inside the pneumatic tire and is assembled to the rim. When the internal pressure of the pneumatic tire is reduced, the support member disposed in the tire air chamber supports the tread portion instead of the side rubber layer, thereby enabling run-flat running.

  Here, the operation of the support shell will be described. When the tread portion of the pneumatic tire receives a load from the road surface during run flat running, the tread portion is deformed so as to swell toward the inner peripheral side along the width direction. A phenomenon occurs in which the vicinity of the center of the portion enters between the two convex portions (inside the concave portion). At this time, a component force to the outside in the width direction acts on each of the two convex portions on the support shell that has received a load from the road surface via the tread portion, and the component shell spreads outward in the width direction by this component force. Thus, elastic deformation occurs. As a result, during run-flat running, the pressure contact force from both ends (legs) of the support member to the rim increases, and the connection strength of the support member to the rim increases. Can be effectively prevented from falling off.

  And since this support shell is shape | molded by the electromagnetic shaping | molding from the aluminum alloy raw material, while being reduced in weight, it shape | molds accurately in the predetermined shape. Therefore, a vehicle equipped with a run-flat tire using a support member made of this support shell has excellent maneuvering stability, can improve fuel consumption, and has a distance that enables stable and safe run-flat travel. Can be extended.

Hereinafter, the present invention will be described in more detail based on examples.
First, a manufacturing apparatus for electromagnetically forming the support shell 26 constituting the support member 16 according to the first invention will be described. As shown in FIG. 1, the manufacturing apparatus 50 includes molding dies 52A and 52B that can be divided along the width direction, and a cylindrical aluminum material 54 set on the divided molding dies 52A and 52B. , Holding members 56A and 56B for holding the aluminum material 54 in a predetermined position, a coil 58 inserted into the aluminum material 54, and an electric circuit 60 for energizing the coil 58. The electric circuit 60 is configured as an equivalent circuit of a so-called impact high current generating circuit, and the electromagnetic force necessary for machining is controlled by energy stored in the capacitor 70 (E = 1/2 · CV ² ). It has become.

  The molding dies 52A and 52B are formed with a molding surface 62 corresponding to the shape of the shell of the support shell 26 on the inner peripheral side, and at a predetermined position of the molding surface 62 for exhaust gas communicating with the outside from the molding surface 62. 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 support shell 26 are respectively formed on the molding surface 62 of the molding dies 52A and 52B over a half circumference. Yes. 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.

Now, the molding dies 52A and 52B and the edge of the aluminum material 54 come into contact with each other at the time of molding. It can't be denied. Therefore, in the present invention, in order to prevent such drawing, the contact surfaces 52A ₀ and 52B ₀ with the edges of the aluminum material 54 of the molding dies 52A and 52B are preferable as shown in FIG. Is formed by forming a groove 81 over the entire circumference, and can be caught on the aluminum material 54 at an early stage of molding, and as a result, drawing can be prevented and desired molding is performed. Is.

  The depth D of the groove 81 is preferably 0.1t ≦ D ≦ 10t with respect to the plate thickness t of the aluminum material 54 to be used. This is because the drawing cannot be ignored and is dragged from the product side. The width W of the groove 81 needs to be W> 2t.

  FIG. 3 is a schematic diagram showing the relationship between the groove 81 and the aluminum material 54 at the time of molding. The aluminum material 54 is deformed and fitted into the groove 81, and this prevents the drawing by the wedge effect. is there.

FIG. 4 shows the contact surfaces 52A ₀ and 52B ₀ with the edges of the aluminum material 54 of the molds 52A and 52B, preferably formed with irregularities 82 over the entire circumference thereof, and the initial stage of molding. As a result, the aluminum material 54 can be caught, and as a result, the drawing can be prevented and the desired forming can be performed.

  The unevenness 82 is preferably Ra: 10 points average roughness of 0.1 to 5 m / m. If it is too small, it will not be caught, and if it is 5 m / m or more, the drawing to the concavo-convex part 82 will increase, the thickness on the molding side will become thin, and the strength will decrease. In addition, the uneven | corrugated width | variety has preferable 1 m / m or more.

Next, a method for manufacturing a support shell according to the second invention will be described with reference to FIG. In this example, the reinforcing ring 74 is formed on the outer side of the aluminum material 54. However, the reinforcing ring 74 may be omitted and may be formed on the inner side. . Now, after the molding dies 52A and 52B of the manufacturing apparatus 50 are divided and the reinforcing ring 74 is inserted into the pair of concave portions 62A and 62B on the molding surface 62 (disposed on the outside) in this example, it is cylindrical. The aluminum material 54 is inserted between the divided molding dies 52A and 52B. Note that the lower end of the aluminum material 54 is supported by a holding member 56B. The contact surfaces 52A ₀ and 53B ₀ of the molding dies 52A and 52B with the aluminum material 54 are provided with grooves 81 having a depth of 5 m / m and a width of 10 m / m.

  In this state, the coil 58 is inserted into the inner peripheral side of the aluminum material 54 as shown in FIG. Here, each of the aluminum material 54 (and the reinforcing ring 74) includes an Al—Mg-based aluminum alloy (for example, JIS designation 5000 series), an Al—Mg—Si-based aluminum alloy (for example, JIS designation 6000 series), and Al. -It is shape | molded by either of Zn type aluminum alloys (for example, JIS name 7000 series).

  Next, as shown in FIG. 5B, the upper and lower ends of the aluminum material 54 are positioned by sliding the holding member 56 </ b> A of the manufacturing apparatus 50 and pressing the upper end of the aluminum material 54. In this state, when a current is passed through the coil 58 by the circuit 60 of the manufacturing apparatus 50, an induced current flows through the aluminum material 54, and at the same time, an edge of the aluminum material 54 is fitted into the groove 81, and at the same time The material 54 receives a pulse-like force (electromagnetic force) in accordance with Fleming's left-hand rule. This electromagnetic force acts to bulge and deform the aluminum material 54 (and the reinforcing ring 74) toward the outer peripheral side. Due to the action of the electromagnetic force, the aluminum material 54 (and the reinforcing ring 74) are pressed against the molding surface 62 instantaneously (usually 0.1 seconds or less), and each of them is plastically deformed along the molding surface 62, and FIG. ) To a predetermined shape.

  When the reinforcing ring 74 is used, at the same time as the plastic deformation due to electromagnetic forming as described above, an impact is applied between the portion corresponding to the vicinity of the peaks PA and PB in the aluminum material 54 and the two reinforcing rings 74. Pressure is applied. As a result, a phenomenon in which metal atoms diffuse mutually occurs at the interface where the inner peripheral surface of the two reinforcing rings 74 and the outer peripheral surface of the aluminum material 54 are in contact with each other, and the two reinforcing rings 74 each have a peak in the aluminum material 54. The parts corresponding to the vicinity of PA and PB are pressure-welded and the two reinforcing rings 74 are substantially integrated with the aluminum material 54, and the parts corresponding to the vicinity of the peaks PA and PB of the protrusions 30A and 30B in the aluminum material 54 The thickened reinforcing portions 32A and 32B are formed respectively.

  When the aluminum material 54 and the reinforcing ring 74 are plastically deformed by electromagnetic molding as described above, the air interposed between the aluminum material 54 and the molding surfaces 62 of the molding dies 52A and 52B causes the deformation of the aluminum material 54 to be instantaneous. Therefore, it is difficult to be discharged to the outside through the gap between the two, but it is smoothly discharged to the outside from the exhaust hole 64 formed in the molding dies 52A and 52B. Therefore, it can be avoided that air remains between the aluminum material 54 and the molding surface 62 during electromagnetic molding, thereby hindering the molding of the support. Further, since the support shell 26 obtained in this way is instantly formed by electromagnetic forming using the aluminum material 54 and the reinforcing ring 74 as a material, the aluminum alloy is deformed before work hardening associated with normal plastic deformation occurs. Complete. Accordingly, the formability of the aluminum alloy is improved, and the aluminum alloy can be accurately formed into a predetermined shape.

  In the obtained support shell 26, thickened reinforcing portions 32A and 32B are provided near the peaks PA and PB of the convex portions 30A and 30B, respectively. Therefore, when the pneumatic tire 10 is run flat using the support member 16 using the support shell 26, the run flat running is performed while the convex portions 30A and 30B are in contact with the tread. Therefore, by providing two reinforced convex portions 30A and 30B, the load from the road surface is more well distributed to two points, so that load concentration on the support shell 26 during run-flat travel is avoided, and the load on the support shell 26 is avoided. The load can be reduced. That is, it is possible to reinforce the portion where damage such as cracks and dents is likely to occur in the vicinity of the peaks PA and PB resulting from the concentration of the load, and to reinforce the thinning due to electromagnetic forming (electromagnetic tube expansion forming). Is.

  In the manufacturing method of the support shell 26 described above, since the aluminum material 54 (and the reinforcing ring 74) is bulged and deformed (electromagnetic forming) by electromagnetic force, it is formed as compared with other processing methods such as hydroforming. The time is very short (usually 0.1 seconds or less), and there is no possibility that deformation is hindered by work hardening during plastic deformation. That is, since the deformation of the aluminum material 54 proceeds in a superplastic deformation region where the material can be deformed without being affected by work hardening, the support shell 26 can be accurately formed into a desired shape without causing cracking, bending, or the like. Can be molded.

  The support shell 26 may be provided with a hole (not shown) for allowing air to flow in the pneumatic tire.

  The support shell 26 was subjected to a predetermined process such as a quenching process, and then the rubber leg 28 was vulcanized and bonded to obtain a completed support member 16.

  Hereinafter, a pneumatic run-flat tire using the support member 16 of the present invention will be described with reference to FIG. As shown in FIG. 6, the run flat tire 10 is a tire in which a pneumatic tire 14 and a support member 16 for a run flat tire are assembled to a rim 12. The rim 12 is a standard rim corresponding to the size of the pneumatic tire 14. And a pair of bead parts 18, a toroid-like carcass 20 extending over both bead parts 18, a plurality (two in this embodiment) of belt layers 22 located in the crown part of the carcass 20, and a belt A tread portion 24 formed on top of the layer 22.

  The support member 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 member 16 has an aluminum alloy support shell 26 and rubber legs 28 vulcanized and formed at both ends of the support shell 26. The pair of leg portions 28 are assembled to the rim 12 together when the support member 16 disposed inside the pneumatic tire 14 is assembled to the rim of the pneumatic tire 14.

  As shown in FIG. 6, the support shell 26 is formed with convex portions 30A, 30B that are convex outward in the radial direction, and concave portions 30C that are convex inward in the radial direction formed between the convex portions 30A, 30B. , 30B are formed on the outer side in the width direction (X direction), side portions 30D and 30E extending from the convex portions 30A and 30B to the inner peripheral side. 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. Further, in the support shell 26, reinforcing portions 32A and 32B are preferably formed in the vicinity of the peaks PA and PB located on the outermost peripheral side of the convex portions 30A and 30B, as shown in the figure. The reinforcing portions 32A and 32B are thicker than other portions of the support shell 26, and are provided over the entire circumference of the convex portions 30A and 30B. The reinforcing portions 32A and 32B have substantially symmetrical shapes along the width direction with the peaks PA and PB of the convex portions 30A and 30B as centers.

  In the pneumatic tire adopting the support member in the present invention, because the predetermined strength is secured and the weight is reduced, the steering stability and fuel consumption of the vehicle equipped with the run-flat tire are improved. It can be widely used for various tires.

FIG. 1 is a side sectional view showing a support shell manufacturing apparatus according to the present invention. FIG. 2 is a side sectional view of the main part of the molding die. FIG. 3 is a side sectional view showing the relationship between the part and the material shown in FIG. FIG. 4 is a side sectional view of the main part of another molding die. FIG. 5 is a side sectional view for explaining the manufacturing process of the support shell of the present invention. FIG. 6 is a cross-sectional view of the pneumatic run-flat tire employing the support member of the present invention when mounted on the rim.

Explanation of symbols

10 run flat tire 12 rim 14 tire 16 supporting member 18 bead portion 20 carcass 24 tread portion 26 supporting the shell 28 leg 32A, 32B reinforcement portion 50 manufacturing apparatus 52A, 52B molding die 52A _0, 52B ₀ of the molding die Contact surface with material 54 Aluminum material 58 Coil 62 Molding surface 74 Reinforcement ring 81 Groove 82 Uneven surface

Claims (5)

  A method of manufacturing a support shell for a run-flat tire, in which a cylindrical aluminum tube is deformed into a desired shape. A first step of placing the aluminum material in the molding die and fixing the end of the aluminum material in contact with the end surface of the molding die; and in the molding die A coil is inserted on the inner circumference side of the aluminum material installed in the coil, and an electric current is applied to the coil to cause electromagnetic force to act on the aluminum material, so that these aluminum materials are plastically deformed into a shape corresponding to the molding die. A method for producing a support shell for a run-flat tire, comprising: a second step.   The manufacturing method of the support shell for run-flat tires of Claim 1 which added the process of superimposing a reinforcement ring on the outer peripheral side or inner peripheral side of the desired site | part in an aluminum raw material before the said 3rd process.   The support shell for a run-flat tire according to claim 1 or 2, wherein the aluminum material is formed using any one of an Al-Mg-based aluminum alloy, an Al-Mg-Si-based aluminum alloy, and an Al-Zn-based aluminum alloy. Manufacturing method.   A device for manufacturing a support shell for a run-flat tire, wherein a groove and / or is formed on an end surface of a molding die that comes into contact with the aluminum material of a molding die that plastically deforms a cylindrical aluminum material into a desired shape An apparatus for manufacturing a support shell for a run-flat tire, characterized in that the irregularities are formed and drawing during molding of the abutting aluminum material is eliminated. The apparatus for manufacturing a run-flat tire support shell according to claim 4, wherein the plastic deformation of the aluminum material is caused by electromagnetic tube expansion forming means.

Images