JP5814628B2 - Rim molding method - Google Patents

Description

  The present invention relates to a method for molding a rim constituting a vehicle wheel, and more particularly to a rim molding method in which a desired portion of a rim is thinned and molded.

  For example, a two-piece wheel constructed by welding a rim and a disk is well known as a vehicle wheel. Here, the rim is generally formed into a desired shape by roll processing after a rectangular metal plate is curved to form a cylindrical element tube.

  In recent years, there is a strong demand for weight reduction of vehicle wheels. Therefore, the rim has a configuration in which a portion having a sufficient strength is thinned, and various forming methods have been proposed. For example, Patent Document 1 discloses a method in which after performing a flare process in which the side wall of the cylindrical element pipe is flared outward in the radial direction, the flare-shaped side wall is stretched and the side surface is contoured by spinning. Proposed. According to this method, the flare-shaped side wall can be stretched and the side surface contoured by a single spinning process. More specifically, in order to form the contour, a well roller (substantially the thickness does not change) is formed by pressing a spinning roller against a predetermined portion from the outside in the radial direction, and the front and back surfaces are further pressed while pressing the roller. By continuously moving in the direction (longitudinal direction), the flare-shaped side wall is thinned and contoured. As described above, since the method of Patent Document 1 can perform stretching and contour formation at the same time by a single spinning process, there is an effect that the time required for rim molding can be shortened.

Special table 2008-509005 gazette

  In the conventional method of Patent Document 1 described above, a well portion is first formed by spinning processing on a molded body (hereinafter referred to as flare molded body) in which a flare-shaped side wall is formed by flare processing, and then thinning is performed by spinning processing. Contouring is performed at once. This is because the well portion is first formed in the flare molded body, and the well portion is fitted to the mold disposed inside the flare molded body, so that the flare molded body is front and back with respect to the mold. This is because positioning is performed so as not to move in the direction, and after that, a portion to be thinned and a portion to be contoured are subjected to spinning processing without misalignment. For this reason, the conventional method of Patent Document 1 has a problem that the formation of the well portion, the thinning, and the contour formation must be performed by spinning, and the time required for the spinning is increased.

  Further, in the above conventional method, since thinning and contour formation are simultaneously performed by a single spinning process, it is difficult to contour a complicated form, and in reality it is necessary to form a contour in a relatively simple form. I can only do that. Furthermore, when the thinned and contoured shape is formed by a spinning process, a load is easily applied locally when the molded body is rolled in a subsequent process, and the rim is wrinkled, sinked, buckled. There is a problem that the possibility of occurrence of the above becomes high.

  The present invention provides a rim molding method capable of reducing the time required for spinning processing for thinning a predetermined portion and suppressing occurrence of wrinkles, sink marks, buckling, and the like during roll processing.

  The present invention provides a flared molded body formed by a flare process in a rim forming method for forming a desired rim by sequentially executing a plurality of roll processes for forming a desired rim shape stepwise after the flare process. After the first roll process is performed, a roll is formed by holding the concave portion after forming a roll forming body having a concave portion recessed radially inward and a roll intermediate forming portion contoured on both sides of the concave portion. In the rim forming method, the forming body is positioned in the front and back directions, and a spinning process is performed in which all or a part of the roll intermediate forming portion is thinned by spinning.

  In this method, the roll formed body in which the concave portion is formed by the first roll step is thinned by spinning, and it is not necessary to form the concave portion in the spinning step, and the time required for the spinning step can be shortened. . Further, in the spinning process, the thinning is performed by performing the spinning process based on the positioning by holding the concave portion formed in the first roll process, and by thinning the roll intermediate forming portion that is contoured by the first roll process. The desired site can be easily identified, and the site can be thinned accurately and stably. In addition, since the spinning process for thinning is performed after the first roll process, the roll process after the spinning process has a small amount of deformation of the roll molded body, and a local load generated during the roll processing. Accordingly, wrinkles, sink marks, buckling, and the like can be suppressed during roll processing. Therefore, according to the rim molding method of the present invention, the time required for the spinning process can be shortened and the wall thickness can be efficiently reduced, and the rim production process can be applied to the rim production process so that the production efficiency of the rim having a thinned desired portion can be stabilized Can be improved.

  Here, the roll intermediate forming portion to be subjected to spinning processing is a portion that is contoured by the first roll step after the flare step, and therefore is different from the portion of the flare molded body. That is, the present invention is characterized in that the roll intermediate forming portion that has been contoured by the first roll step is subjected to spinning processing, and in accordance with this, the above-described operational effects are achieved.

  In the rim forming method described above, the roll intermediate forming portion that is contoured by the first roll step includes a ledge intermediate forming portion for forming the ledge portion and a bead sheet intermediate forming portion for forming the front and back bead sheet portions. A method is proposed in which it is assumed that the configuration is provided.

  In this method, part or all of the ledge intermediate forming portion and the bead sheet intermediate forming portion are thinned by the spinning process. Here, since the ledge portion and the bead seat portion have a sufficient margin as compared with the flange portion and the like, the rim can be reduced in weight to reduce the weight of the rim. Further, in the spinning process, the ledge intermediate forming part and the bead sheet intermediate forming part are subjected to spinning processing, so that the ledge part and the bead sheet part, which are the thinning target parts, can be accurately and easily specified and thinned. . As a result, the spinning process can be performed efficiently, which can further contribute to shortening the time of the spinning process.

  In the rim forming method described above, the spinning step is inserted from the front and back sides of the roll molded body, and the first mandrel roll having a first step portion that supports the recess from the one side, the front and back sides of the roll molded body, and the like. The second mandrel roll that is fitted from the side and has a second step portion that supports the recess from the other side, holds the recess and positions in the front and back direction, and does not hold the front and back ends of the roll molded body In this state, a method is proposed in which a spinning roll is pressed from the radially outer side of the roll formed body to spin all or part of the roll intermediate forming portion.

  In such a method, since the first mandrel roll and the second mandrel roll that perform spinning processing in cooperation with the spinning roll are fitted from both the front and back sides of the roll molded body, respectively, the concave portions are held. It can be performed stably and accurately, and also contributes to shortening the time of the spinning process by not forming the recesses by spinning. And since a recessed part can be hold | maintained stably, spinning process can be performed, without hold | maintaining the front and back both ends of a roll molded object. Thereby, in the case of a spinning process, a spinning process can be performed suitably, without the movement of the front and back both ends of a roll molded object being restrict | limited.

  Note that the concave portion and the first step portion and the second step portion supporting the concave portion may be in contact with each other without a gap while holding the concave portion, or may have a partial gap. That is, the roll molded body may be formed so that the concave portion is shaped to follow the first step portion and the second step portion, or the concave portion can be held by the first step portion and the second step portion. If it exists, it may be formed as a different shape.

  In the rim forming method described above, the spinning step is proposed by spinning the whole or part of the roll intermediate forming portion by moving the spinning roll from the portion near the concave portion of the roll molded body in a direction away from the concave portion. Is done.

  In this method, since the spinning process is performed from the concave portion held by the first and second mandrel rolls toward the end portion that is not held, the roll intermediate forming portion that is subjected to the spinning processing is preferably stretched toward the end portion to reduce the thickness. it can.

  In addition, this method can perform a spinning process with one spinning roll. In the spinning process, the spinning roll may be moved only on the front or back side of the recess, or both the front and back sides may be moved sequentially.

  In the rim forming method described above, the spinning step includes spinning the whole or part of the roll intermediate forming portion by moving the two spinning rolls in directions away from the front and back side portions of the concave portion of the roll formed body. A method is proposed.

  In such a method, since the roll intermediate forming portions contoured on both sides of the concave portion by the two spinning rolls are respectively subjected to the spinning process, the time required for the spinning process can be further shortened. In particular, the time can be shortened as much as possible by moving two spinning rolls almost simultaneously.

  In the rim forming method described above, a spinning method is proposed in which all or part of the intermediate roll forming portion is spun while the concave portion of the roll formed body is pressed by the center guide roll from the outside in the radial direction.

  In this method, since the concave portion is held from the inside and outside by the first and second mandrel rolls and the center guide roll, the roll molded body can be positioned more stably and reliably, so that the processing accuracy of the spinning process can be further improved.

  In the rim molding method of the present invention, after the flare process, a first roll process is performed in which the concave portion and the roll intermediate forming portion are contoured, and the roll molded body molded by the first roll step is retained by holding the concave portion. This is a method in which a spinning process in which all or a part of the intermediate roll forming part is thinned by a spinning process is performed by positioning in the direction, so there is no need to form a recess in the spinning process, and the conventional method described above Compared to the above, the time required for the spinning process can be shortened. Further, since the roll intermediate forming portion is subjected to the spinning process based on the positioning by holding the concave portion, the target portion for thinning can be easily specified, and the thinning can be performed accurately and stably. In addition, since the spinning process for thinning is performed after the first roll process, the amount of deformation of the roll molded product is reduced in the roll process after the spinning process, reducing the load caused by the roll process after the spinning process. And the occurrence of wrinkles, sink marks, buckling and the like can be suppressed. From the above, according to the rim molding method of the present invention, the time required for the spinning process can be shortened, and the occurrence of wrinkles, sink marks, buckling, and the like can be suppressed during roll processing.

1 is a longitudinal sectional view of a vehicle wheel 1. 5 is an explanatory diagram of a molding process of the rim 2. FIG. It is explanatory drawing of the shaping | molding process continued from FIG. It is explanatory drawing of the 1st roll process of Example 1. FIG. 6 is an explanatory diagram of a spinning process of Example 1. FIG. It is explanatory drawing of the spinning process which continues from FIG. It is explanatory drawing of the spinning process of Example 2. FIG.

Embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a longitudinal sectional view of a vehicle wheel 1. This vehicle wheel 1 is a so-called two-piece united by fitting and welding a rim 2 formed from a steel plate and a disk 3 together. This is a type of steel wheel. In this embodiment, the direction from the back side of the disk 3 to the design surface side is the front direction, and the reverse direction is the back direction. A direction toward the central axis L of the vehicle wheel 1 along the wheel radial direction is defined as a radially inward direction, and a reverse direction is defined as a radially outward direction.

  Here, the rim 2 is formed with rim flange portions 11 and 12 at the opening edges of both front and back ends, and front and back bead seat portions 13 and 14 are coupled to the rim flange portions 11 and 12, respectively. Further, a well portion 15 that is recessed radially inward is formed between the front and back bead sheet portions 13 and 14, and a ledge portion 16 is coupled between the well portion 15 and the back side bead sheet portion 14. . The molding method of the rim 2 is the main part of the present invention, and details will be described later.

  On the other hand, the disk 3 is extended from the outer periphery of the hat portion 22 to the rear side, the hub mounting portion 21 having a hub hole 27 in the center, the hat portion 22 protruding from the outer peripheral edge of the hub mounting portion 21 to the front side. Disc flange portion 23. The hub attachment portion 21 is provided with bolt holes 26 at equal intervals in the circumferential direction, and the hat portion 22 is provided with a plurality of decorative holes 28 at equal intervals in the circumferential direction. Such a disk 3 can be formed by pressing a disk-shaped steel flat plate, and can be formed in the same manner as in the prior art. Therefore, the description of the forming step is omitted.

  The disc 3 is fitted into the rim 2 and the disc flange portion 23 of the disc 3 and the well portion 15 of the rim 2 are welded to obtain the vehicle wheel 1 of the present embodiment. Since the welding process can be performed in the same manner as in the prior art, the description thereof is omitted.

Next, the molding process of the rim 2 according to the main part of the present invention will be described.
As shown in FIG. 2A, a cylindrical element tube 32 is obtained by curving a substantially rectangular steel flat plate 31 and abutting and welding the short sides thereof.

  Thereafter, as shown in FIG. 2 (B), the both-end openings are expanded by pressing the frusto-conical flare molds 41 and 41 from the both-end openings of the cylindrical tube 32 by a flare process, respectively. Flared end portions 33a and 33a are formed, and a flare molded body 33 including the flare-shaped end portions 33a and 33a is formed. In the next first roll process, as shown in FIG. 2 (C), an intermediate form that is clamped by the first inner mold 43 and the first outer mold 44 from the inside and outside of the flare molded body 33 to reach a desired rim form. The first roll molded body 51 is formed by forming a contour. In the next spinning step, as shown in FIG. 3 (A), the first mandrel roll 91 and the second mandrel roll 92 are fitted into the first roll molded body 51, and the spinning rolls 93a and 93b are pressed from the outside. Thin the part partially. In the next second roll step, as shown in FIG. 3 (B), the second inner mold 45 and the second outer mold 46 sandwich the partially rolled first roll molded body 51 'from the inside and outside. The second roll molded body 52 is contoured. In the next third roll step, as shown in FIG. 3 (C), the inside and outside of the second roll molded body 52 is clamped by the third inner mold 47 and the third outer mold 48, and the bead sheet portions 13 on the front and back sides are formed. 14, the well portion 15, the ledge portion 16 and the like are contoured to form the rim 2. The desired rim 2 is obtained by adjusting to a perfect circle by the following expanding process (not shown).

  Hereinafter, the first roll process and the spinning process of Examples 1 and 2 will be described in detail.

  In the first roll process, the flare molded body 33 is loosely fitted in the first inner mold 43 arranged on the inside as shown in FIG. 4A, and the first outer mold is formed from the outside as shown in FIG. 4B. 44 is pressed against the flare molded body 33. At this time, by pressing the flare molded body 33 while rotating the first inner mold 43 and the first outer mold 44, the flare molded body 33 is rotated in the circumferential direction to roll.

  Here, the first inner mold 43 includes an inner recess forming portion 81 that is recessed radially inward, an inner front intermediate forming portion 82 provided on the front side of the inner recess forming portion 81, and a back side of the inner recess forming portion 81. The inner back intermediate first forming portion 83 and the inner back intermediate second forming portion 84 provided on the inner back. On the other hand, the first outer mold 44 includes an outer convex portion forming portion 86 facing the inner concave portion forming portion 81, an outer front intermediate forming portion 87 facing the inner front intermediate forming portion 82, and the inner rear intermediate portion. An outer back intermediate first forming portion 88 facing the one forming portion 83 and an outer back intermediate second forming portion 89 facing the inner front intermediate second forming portion 84 are provided.

  In the first roll process, the outer recessed portion forming portion 86 is pressed into the inner recessed portion forming portion 81 to form the recessed portion 66 that is recessed radially inward with respect to the flare molded body 33. The front side bead sheet intermediate forming part 63 for forming the front side bead sheet part 13 on the flare molded body 33 is contoured by the clamping pressure between the inner front intermediate forming part 82 and the outer front intermediate forming part 87. A ledge intermediate forming portion 67 for forming the ledge portion 17 on the flare molded body 33 is contoured by the clamping pressure between the inner back intermediate first forming portion 83 and the outer back intermediate first forming portion 88. The back side bead sheet intermediate forming part 64 for forming the back side bead sheet part 14 with respect to the flare molded body 33 is contoured by the clamping pressure between the inner back intermediate second forming part 84 and the outer back intermediate second forming part 89. To do.

  Thus, the concave portion 66, the front bead sheet intermediate forming portion 63, the ledge intermediate forming portion 67, and the back bead are formed on the flare molded body 33 by the clamping pressure between the first inner die 43 and the first outer die 44. By forming the sheet intermediate forming portion 64, the first roll molded body 51 including the concave portion 66, the front bead sheet intermediate forming portion 63, the ledge intermediate forming portion 67, and the back side bead sheet intermediate forming portion 64 is contoured. That is, the first roll molded body 51 has a configuration different from the flare molded body 33 because the contour is formed by rolling the flare molded body 33.

  A spinning process is performed after the first roll process. In the spinning step, as shown in FIGS. 5A and 5B, the first mandrel roll 91 is fitted from the front side of the first roll molded body 51 and the second mandrel roll is inserted from the back side of the first roll molded body 51. 92 is inserted. Here, the first mandrel roll 91 is in contact with the first step portion 95 that is in contact with and supported by the front inner peripheral surface of the recess 66 of the first roll molded body 51 and the inner peripheral surface of the front bead sheet intermediate forming portion 63. And a front peripheral portion 96 to be supported. On the other hand, the second mandrel roll 92 is in contact with and supported by the inner peripheral surface of the ledge intermediate forming portion 67 and the second step portion 97 that contacts and supports the inner peripheral surface of the recess 66. 98 and a back-side second peripheral portion 99 that contacts and supports the inner peripheral surface of the back-side bead sheet intermediate forming portion 64.

  In the first embodiment, as shown in FIG. 5 (B), the first step portion 95 and the second step portion 97 are substantially aligned with the inner peripheral surface of the recess 66 by the first mandrel roll 91 and the second mandrel roll 92. The first roll molded body 51 is positioned in the front and back direction position while being held in contact with no gap. Further, the front side bead sheet intermediate forming part 63, the ledge intermediate forming part 67, and the back side bead sheet intermediate forming of the first roll molded body 51 by the front side peripheral part 96, the back side first peripheral part 98, and the back side second peripheral part 99. The part 64 is supported. In addition, in the state of FIG. 5 (B), the both-ends opening part of the 1st roll molded object 51 is not hold | maintained.

  By rotating the first mandrel roll 91 and the second mandrel roll 92 fitted in the first roll molded body 51 in the circumferential direction, the first roll molded body 51 is rotated in the circumferential direction. Then, the spinning rolls 93 a and 93 b are pressed from the outside of the first roll molded body 51 as shown in FIG. 6A while rotating the first roll molded body 51. Here, the front-side spinning roll 93a is pressed against the back end of the front-side bead sheet intermediate forming portion 63 of the first roll molded body 51 from the radially outer side, and the front-side bead sheet intermediate forming portion 63 as shown in FIG. 6B. Move toward the front edge of the. On the other hand, the back side spinning roll 93b is pressed from the outside in the radial direction to the front end of the ledge intermediate forming portion 67 as shown in FIG. 6 (A), and is directed toward the back end of the ledge intermediate forming portion 67 as shown in FIG. 6 (B). To move. The operation is controlled so that the spinning rolls 93a and 93b on both sides start to move simultaneously.

  By controlling the operation of the two spinning rolls 93a and 93b in this way, the front bead sheet intermediate forming portion 63 is extended to the front side to be thinned, and the ledge intermediate forming portion 67 is extended to the back side to be thinned. By this spinning process, a first roll formed body 51 ′ having a thin front bead sheet intermediate forming portion 63 ′ and a ledge intermediate forming portion 67 ′ is obtained. In this spinning process, only the spinning process for partially thinning the first roll molded body 51 formed in the contour in the first roll process is performed, and no contour is formed.

  The rim 2 in which the front bead sheet portion 13 and the ledge portion 16 are thinned is formed by sequentially executing the second roll step, the third roll step, and the expanding step described above after the spinning step.

  In the first embodiment described above, in the spinning process, the concave portions 66 formed by the first roll process are held by the first mandrel roll 91 and the second mandrel roll 92 so that the front and back direction positions of the first roll molded body 51 are determined. Positioning is performed, and a spinning process is performed to reduce the thickness of the front bead sheet intermediate forming portion 63 and the ledge intermediate forming portion 67 which are contoured by the first roll process. Thereby, only the thinning process is performed in the spinning process, and the time required for the spinning process can be shortened. Furthermore, since positioning can be performed easily and stably by positioning the recess 66 formed in the first roll process as a reference, the spinning roll can be controlled by using the recess 66 as a reference, and the front bead sheet intermediate forming portion 63 and the ledge intermediate forming portion 67 can be accurately and stably spun. Further, in the spinning process, the spinning rolls 93a and 93b are moved toward the both-end opening portions without holding the both-end opening portions of the first roll molded body 51, so that the front-side bead sheet intermediate forming portion 63 is moved. When the ledge intermediate forming portion 67 is stretched, the movement of the opening portions at both ends of the first roll molded body 51 is not limited, and the spinning process can be suitably performed. Furthermore, since the spinning process for thinning is performed after the first roll process, the roll process after the spinning process has a small amount of deformation of the roll molded bodies 51 ′ and 52, and each roll processing is performed. Therefore, it is possible to reduce the local load generated in the process, and to suppress the occurrence of wrinkles, sink marks, buckling, and the like during roll processing. From the above, according to the rim molding process of the first embodiment, the time required for the spinning process can be shortened and the thickness can be efficiently reduced, and the rim partially thinned by being applied to the rim production process. The production efficiency of producing 2 can be stably improved.

  In the first embodiment, the first roll formed body 51 constitutes the roll formed body according to the present invention. Moreover, the roll intermediate | middle formation part concerning this invention is comprised by the front side bead sheet intermediate | middle formation part 63, the ledge intermediate | middle formation part 67, and the back side bead sheet intermediate | middle formation part 64. FIG.

  In Example 2, the first mandrel roll 91 and the second mandrel roll 92 are placed in the first roll formed body 51 as shown in FIG. Further, the center guide roll 94 is brought into contact with the recess 66 from the outside of the first roll molded body 51. Thereby, since the recessed part 66 can be pinched and hold | maintained from the inside and outside, the effect | action which hold | maintains this recessed part 66 is high, and the 1st roll molded object 51 can be positioned more stably. And since the spinning process is performed by the spinning rolls 93a and 93b as shown in FIG. 7B with the position of the recess 66 held in this way, the spinning process can be performed more stably. Processing accuracy can be further improved.

  Also in the second embodiment, the time required for the spinning process can be shortened as in the case of the first embodiment, and the occurrence of wrinkles, sink marks, buckling, and the like can be suppressed during the roll processing. 2 production efficiency can be improved stably.

  The second embodiment is the same as the first embodiment described above except that the recess 66 is held by the center guide roll 94 in the spinning process, and the same components are denoted by the same reference numerals and the description thereof is omitted. .

  On the other hand, in the case of Examples 1 and 2 described above, the front bead sheet intermediate forming portion and the ledge intermediate forming portion are thinned by the spinning process. In addition to this, the back bead sheet intermediate forming portion is also thin. The spinning roll may be controlled to operate. In this case, since the area to be thinned is widened, the weight reduction effect is further improved. Further, depending on the configuration of the rim, there is a configuration that does not include a ledge portion. In such a configuration, the front side bead sheet intermediate forming portion and the back side bead sheet intermediate forming portion can be thinned.

  Thus, in the spinning process, it can be set to spin any one or two places of the front side bead sheet intermediate forming part, the back side bead sheet intermediate forming part, and the ledge intermediate forming part. Or it can also set so that all the three places of the said intermediate formation part may be processed.

  In the first and second embodiments, the spinning process is performed by using two spinning rolls in the spinning process. However, as another method, the spinning process may be performed by using one spinning roll. For example, when thinning the front bead sheet intermediate forming portion and the ledge intermediate forming portion in the same manner as in Example 1, first, the spinning roll was moved from the back end of the front bead sheet intermediate forming portion to the front end to reduce the thickness. Later, the spinning roll is controlled to move so that the spinning roll moves from the front end to the back end of the ledge intermediate forming portion and is thinned.

  In Examples 1 and 2, the concave portion is positioned in contact with the first step portion of the first mandrel roll and the second step portion of the second mandrel roll in the spinning process with almost no gap. As a method of this, positioning may be performed with a gap between the concave portion and the first step portion and the second step portion. That is, as long as the concave portion can be positioned, a gap may be provided between the first step portion and the second step portion.

  Further, in Examples 1 and 2, only the process of thinning the front side bead sheet intermediate forming part and the ledge intermediate forming part is performed in the spinning process, but at the same time as the spinning process, the process of changing the shape of each intermediate forming part May be performed.

  The present invention is not limited to the above-described embodiments, and configurations other than the embodiments can be appropriately implemented within the scope of the present invention.

2 Rim 13 Front side bead sheet part 14 Back side bead sheet part 16 Ledge part 33 Flare molded body 51 First roll molded body (roll molded body)
63 Front side bead sheet intermediate forming part (roll intermediate forming part)
64 Back side bead sheet intermediate forming part (roll intermediate forming part)
66 Concave part 67 Ledge intermediate forming part (roll intermediate forming part)
91 First Mandrel Roll 92 Second Mandrel Roll 93a Front Side Spinning Roll 93b Back Side Spinning Roll 94 Center Guide Roll 95 First Step 96 Second Step

Claims (8)

In the rim forming method of forming a rim having a desired rim flange portion and a bead sheet portion by sequentially executing a plurality of roll steps for forming a contour in a desired rim form after the flare step.
After running the first roll shaping flare compact molded by flaring process, the roll forming body and a roll intermediate forming portion that is contoured on both sides of the recess and the recess dented inward in the radial direction In addition, before the roll process for completing the contour formation of the rim flange part or the bead sheet part ,
Rim forming characterized in that a roll forming body is positioned in the front and back direction by holding the concave portion, and a spinning process is performed in which all or part of the roll intermediate forming portion is thinned by spinning processing. Method. The rim forming method according to claim 1, wherein the spinning step is executed after the first roll step and before the second roll step. The roll intermediate forming portion that is contoured by the first roll step includes a ledge intermediate forming portion for forming a ledge portion and a bead sheet intermediate forming portion for forming front and back bead sheet portions. The rim forming method according to claim 1 or 2 . The spinning process
A first mandrel roll having a first step portion that is inserted from one side of the roll molded body and supports the recess from the one side, and a recess is inserted from the other side of the roll molded body from the other side. With the second mandrel roll provided with the second step portion that supports the concave portion, the concave portion is held and positioned in the front and back direction,
The whole or part of the roll intermediate forming part is subjected to spinning processing by pressing the spinning roll from the outside in the radial direction of the roll molded body without holding both front and back ends of the roll molded body. The rim forming method according to any one of claims 1 to 3 . Spinning process, by moving the spinning roll from the recess portion close roll forming body in a direction away from the recess, according to claim 4, characterized in that the spinning all or part of the roll intermediate forming portion Rim forming method. Spinning process, the two spinning rolls, by respectively move away from each other from the front and back sides site of the recess of the roll forming body claims characterized by spinning the whole or part of the roll intermediate forming portion The rim forming method according to claim 4 or 5 . 7. The spinning process according to claim 4 , wherein all or part of the intermediate roll forming portion is subjected to a spinning process in a state where the concave portion of the roll molded body is pressed from the radially outer side by the center guide roll. The rim molding method according to any one of the above. In the rim forming method for forming a desired rim by sequentially executing a plurality of roll steps for forming a contour in a desired rim form stepwise after the flare step,
  After performing the first roll process of forming the flare molded body formed by the flare process into a roll molded body having a concave portion recessed radially inward and a roll intermediate forming portion contoured on both front and back sides of the concave portion,
  A roll forming body is positioned in the front and back direction by holding the concave portion, and a spinning process for thinning all or part of the roll intermediate forming portion by spinning processing,
The spinning step is a rim forming method characterized in that all or part of the roll intermediate forming portion is subjected to a spinning process in a state where the concave portion of the roll formed body is pressed by the center guide roll from the outside in the radial direction.

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