JP6154381B2 - Manufacturing method of wheel rim for vehicle - Google Patents

Description

  The present invention relates to a method for manufacturing a vehicle wheel rim, and more particularly, to a method for manufacturing a vehicle wheel rim that manufactures a vehicle wheel rim from a ring.

  Patent Document 1 discloses a method of manufacturing a wheel in which a rim 6 and a disk 7 are integrated as shown in FIG. Patent Document 1 discloses a method of forming the rim 6 by press using an outer peripheral die 8a and an inner peripheral die 8b.

However, the method for manufacturing a vehicle wheel rim disclosed in the above publication has the following problems.
Since the rim 6 and the disk 7 are integrated, it is necessary to use a circular flat plate. Therefore, a rectangular flat plate cannot be used as it is, and there is a waste of material. In addition, since a circular flat plate is drawn into a rim portion, a large deformation process has already been applied before the rim portion is pressed. It is difficult to form a high-quality rim portion by press molding the rim portion.

European Patent Application Publication No. 0148066

  The objective of this invention is providing the manufacturing method of the wheel rim for vehicles which can suppress generation | occurrence | production of the waste of material.

The present invention for achieving the above object is as follows.
(1) An elemental ring preparation step in which a rectangular steel plate is wound into a cylindrical shape and both ends of the winding are welded to each other to form an elemental ring;
An outer peripheral mold divided in the circumferential direction and an inner peripheral mold are moved with respect to the elemental ring to reduce the diameter of the elemental ring by the outer peripheral mold and the diameter expansion of the elemental ring by the inner peripheral mold. A rim forming step performed by pressing, wherein the element ring is formed into a rim shape;
I have a,
In the rim forming step, the vehicle wheel rim manufacturing method is such that the maximum value of the diameter expansion of the elemental ring is larger than the maximum value of the diameter reduction of the elemental ring .
(2) The vehicle rim manufacturing method according to (1), wherein the rim forming step includes at least one rough forming step and a finishing step.
(3) The vehicle according to (1) or (2), wherein in the rim forming step, the moving speed and moving distance of the outer peripheral mold and the moving speed and moving distance of the inner peripheral mold are adjusted respectively. Wheel rim manufacturing method .
(4 ) In the rim forming step, the element ring is reduced in diameter to form a drop bottom surface portion of the wheel rim and at least a part of the first and second sidewall portions,
In the rough forming step, the diameter of the elemental ring is reduced, and the end part of the first sidewall part opposite to the drop bottom part in the axial direction of the elemental ring and the second sidewall part The manufacturing method of the wheel rim for vehicles as described in (2) provided with the process of shape | molding the recessed part whose width | variety is smaller than the space | interval with the edge part on the opposite side to the said drop bottom face part.

According to the vehicle wheel rim manufacturing method of the above (1), the following effects can be obtained.
Since the rim forming process is performed by pressing, the rim can be formed by using an outer peripheral mold and an inner peripheral mold of a general-purpose press. In addition, since a rectangular steel sheet is wound into a cylindrical shape, and both ends of the winding are welded to each other to form an element ring, and a rim forming step for making the element ring into a rim shape, A rim can be produced using a flat plate. Therefore, since it is not necessary to use a circular flat plate, it is possible to suppress the generation of waste of materials and to easily form a rim as compared to the case of using a circular flat plate.
In the rim forming process, the maximum value of the amount of expansion of the elemental ring is set larger than the maximum value of the amount of diameter reduction of the elemental ring. The risk of occurrence can be suppressed, and a rim with good quality can be molded.

According to the vehicle wheel rim manufacturing method of (2) above, the following effects can be obtained.
Since the rim forming step includes at least one rough forming step and a finishing step, a rim with good quality can be formed.

According to the vehicle wheel rim manufacturing method of (3) above, the following effects can be obtained.
In the rim forming process, each of the movement speed and stroke of the outer peripheral mold and each of the movement speed and stroke of the inner peripheral mold are adjusted so that the occurrence of shrinkage, wrinkles, etc. is suppressed and accuracy is improved. The rim can be molded well .

According to the vehicle wheel rim manufacturing method of ( 4 ) above, the following effects can be obtained.
Since the rough forming step includes a step of forming the recess by reducing the diameter of the elemental ring, it is possible to efficiently form a rim with higher efficiency and better quality.

It is process drawing of an element ring preparation process of a manufacturing method of a wheel rim for vehicles of an example of the present invention. (A) shows the strip | belt-shaped member wound by the coil shape. (B) shows a flat rectangular steel plate. (C) shows the state by which a steel plate is wound cylindrically. (D) shows the state which weld-joins the both ends of winding. (E) shows a state in which the rise and burrs of the welded portion are trimmed. (F) represents a prime ring. It is process drawing of the rim formation process of the manufacturing method of the wheel rim for vehicles of this invention Example. For clarity of the drawing, the cross-sectional display of parts other than the elemental ring and the rim is omitted. (A) shows the state before the rough forming process of a rim forming process. (B) shows the state after the rough forming step of the rim forming step. (C) shows the state before the finishing process of a rim forming process. (D) shows the state after the finishing process of a rim forming process. It is a partial half sectional view of the modification of the rough forming ring after the rough forming step in the vehicle wheel rim manufacturing method of the embodiment of the present invention. It is a partial half sectional view of the modification of the rough forming ring after the rough forming step in the vehicle wheel rim manufacturing method of the embodiment of the present invention. FIG. 10 is a half cross-sectional view of a modified example of the rough forming ring after the rough forming step in the vehicle wheel rim manufacturing method of the embodiment of the present invention. It is a half sectional view of the rim manufactured by the manufacturing method of the wheel rim for vehicles of the example of the present invention. In the outer rim type and inner rim type used in the method of manufacturing the vehicle wheel rim according to the embodiment of the present invention, both the outer rim type and the inner rim type are the circumferential division type, and the phases of the outer rim type and the inner rim type are matched. FIG. For the sake of clarity, the cross-sectional display of parts other than the elemental ring is omitted. In the outer periphery type and the inner periphery type used in the method for manufacturing the vehicle wheel rim according to the embodiment of the present invention, both the outer periphery type and the inner periphery type are circumferentially divided types, and the phases of the outer periphery type and the inner periphery type are different. It is sectional drawing in the case. For the sake of clarity, the cross-sectional display of parts other than the elemental ring is omitted. In the outer periphery type and the inner periphery type used in the method for manufacturing a vehicle wheel rim according to the embodiment of the present invention, both the outer periphery type and the inner periphery type are circumferential division types, and the number of divisions of the outer periphery type and the inner periphery type is different. FIG. For the sake of clarity, the cross-sectional display of parts other than the elemental ring is omitted. It is a fragmentary sectional view of the press machine used for the manufacturing method of the wheel rim for vehicles of the example of the present invention in the state where the press machine was operated and the outer periphery type and the inner periphery type were reduced. For the sake of clarity, the cross-sectional display of parts other than the elemental ring is omitted. It is sectional drawing when both the outer periphery type | mold and inner periphery type | mold are the axial direction division | segmentation type in the outer periphery type | mold and inner periphery type | mold used with the manufacturing method of the wheel rim for vehicles of this invention Example. For the sake of clarity, the cross-sectional display of parts other than the elemental ring is omitted. It is sectional drawing in case the radial direction retreat part is provided in the inner periphery type in the outer periphery type | mold and inner periphery type | mold used with the manufacturing method of the wheel rim for vehicles of this invention Example. For the sake of clarity, the cross-sectional display of parts other than the elemental ring is omitted. It is sectional drawing when the radial direction retraction part is provided in each of the outer periphery type | mold and inner periphery type | mold used with the manufacturing method of the wheel rim for vehicles of this invention Example. For the sake of clarity, the cross-sectional display of parts other than the elemental ring is omitted. It is sectional drawing of the shaping type | mold in the rim shaping process of the manufacturing method of the wheel rim for vehicles of this invention Example. For the sake of clarity, the cross-sectional display of parts other than the elemental ring is omitted. It is a figure which shows the modification of the manufacturing method of the wheel rim for vehicles of this invention Example, and is a half sectional view of an outer periphery type | mold and an inner periphery type | mold when an inner periphery type | mold is an axial press type | mold. For the sake of clarity, the cross-sectional display of parts other than the elemental ring is omitted. It is a schematic sectional drawing of the rim shaping | molding apparatus of the manufacturing method of the conventional wheel rim for vehicles.

Below, the manufacturing method of the wheel rim for vehicles of this invention Example is demonstrated with reference to FIGS.
The vehicle wheel rim (hereinafter also simply referred to as a rim) 30 according to the embodiment of the present invention is a method of manufacturing the rim 30 from the element ring 20 as shown in FIGS. The material of the element ring 20 is steel. The rim 30 is, for example, a rim for passenger cars, trucks / buses, and industrial vehicles.

As shown in FIG. 6, the rim 30 has a first flange portion 30a, a first bead sheet portion 30b, a hump portion 30h, a drop portion 30d (the drop portion 30d A first side wall portion 30c, a drop bottom surface portion 30d1, and a second side wall portion 30e), a second bead sheet portion 30f, and a second flange portion 30g. A disc (not shown) is fitted into the rim and welded to form a welding type wheel.
However, although not shown, the rim 30 does not have one of the first flange portion 30a or the second flange portion 30g, and is a full-face wheel that is joined to the back surface of a disk (not shown) with a bead seat portion. A rim may be used.

  As shown in FIG. 1, the manufacturing method of the rim 30 according to the embodiment of the present invention includes a ring manufacturing step in which a rectangular steel plate 10 is wound into a cylindrical shape and both ends of the winding are welded together to form a ring 20. 2, the outer peripheral mold 41 and the inner peripheral mold 42 divided in the circumferential direction are moved with respect to the main ring 20 (rough forming ring 40), and the main ring 20 ( This is performed by a press which reduces the diameter of the rough forming ring 40) and expands the diameter of the element ring 20 (rough forming ring 40) by the inner peripheral die 42, and makes the element ring 20 (rough forming ring 40) into the shape of the rim 30. A rim forming step. The diameter reduction of the elemental ring 20 (rough forming ring 40) by the outer peripheral mold 41 and the diameter expansion of the elemental ring 20 (rough forming ring 40) by the inner peripheral mold 42 are simultaneously performed on the elemental ring 20 (rough forming ring 40). It is performed all around. Further, the diameter reduction of the elemental ring 20 (rough forming ring 40) by the outer peripheral mold 41 and the diameter expansion of the elemental ring 20 (rough forming ring 40) by the inner peripheral mold 42 may be performed simultaneously (in the same process). .

The maximum inner diameter of the outer peripheral mold 41 when the outer peripheral mold 41 is expanded most is larger than the maximum outer diameter of the rim 30 so that the outer peripheral mold 41 can be removed from the rim 30. Further, the maximum outer diameter of the inner peripheral mold 42 when the inner peripheral mold 42 is most contracted is smaller than the maximum inner diameter of the rim 30 so that the inner peripheral mold can be removed from the rim 30.

In the elemental ring manufacturing step, as shown in FIG. 1, a flat rectangular steel plate 10 is obtained by, for example, pulling the belt-like member 11 linearly from the belt-like member 11 wound in a coil shape for each predetermined length. It is produced sequentially by cutting. Next, the flat rectangular steel plate 10 is wound into a cylindrical shape, both ends of the winding are butted against each other and welded together by flash butt welding, butt welding, arc welding, or the like, and the rise and burrs of the welded portion 12 are trimmed. Thus, the element ring 20 is produced.
In the elemental ring production step, although not shown, the elemental ring 20 may be produced by cutting a pipe-shaped material into a predetermined length.

  The rim forming process is performed by pressing. In the rim forming step, the blank 20 is set in the press machine 50 as shown in FIG. Thereafter, the press machine 50 is operated to move (crush) the outer peripheral die 41 and the inner peripheral die 42 with respect to the elemental ring 20, and the elemental ring 20 is formed into a rim shape. The drop portion 30 d of the rim 30 is formed by reducing the diameter of the element ring 20. The first flange portion 30 a and the second flange portion 30 g of the rim 30 are formed by expanding the diameter of the element ring 20.

As shown in FIG. 7, the outer peripheral mold 41 is a circumferentially divided mold that is divided in the circumferential direction. The outer peripheral die 41 is disposed on the outer side in the radial direction (hereinafter also simply referred to as the radial direction) of the element ring 20 (rough forming ring 40). The outer peripheral die 41 moves (reduces diameter) in the radial direction with respect to the element ring 20 (rough forming ring 40), thereby reducing the diameter of the element ring 20 (rough forming ring 40).

The inner circumferential mold 42 is a circumferential division mold divided in the circumferential direction. The inner peripheral mold 42 is arranged on the inner side in the radial direction of the element ring 20 (rough forming ring 40). The inner peripheral die 42 moves (expands) in the radial direction of the elemental ring 20 (roughly formed ring 40) with respect to the elemental ring 20 (roughly formed ring 40). Expand the diameter.
However, as shown in the modified example of FIG. 15, the inner peripheral die 42 includes a portion having a diameter larger than that of the elemental ring 20 (roughly formed ring 40). It may be an axial press die that moves (rolls and presses) in the axial direction of the element ring 20 (rough forming ring 40) to expand the diameter of the element ring 20 (rough forming ring 40). When the inner peripheral mold 42 is an axial press mold, the inner peripheral mold 42 may or may not be divided in the circumferential direction, but is divided only in the axial direction and divided in the circumferential direction. It is better not to.
Hereinafter, in the embodiment of the present invention, a case where the inner circumference type is a circumferential division type will be described.

  The number of divisions in the circumferential direction of the outer peripheral mold 41 and the inner peripheral mold 42 may be the same as shown in FIGS. 7 and 8, or may be different as shown in FIG. When the number of divisions in the circumferential direction of the outer periphery mold 41 and the inner periphery mold 42 is different, the number of divisions of the outer periphery mold 41 may be larger or smaller than the number of divisions of the inner periphery mold 42. Moreover, the phase in the circumferential direction of the outer periphery type | mold 41 and the inner periphery type | mold 42 may correspond as shown in FIG. 7, and may differ as shown in FIG.

In the rim forming step, the movement (reduction diameter) speed and movement distance of the outer peripheral mold 41 and the movement (expansion) speed and movement distance of the inner peripheral mold 42 are adjusted, respectively.
The diameter reduction speed and the moving distance of the outer peripheral mold 41 are configured to be changeable. Further, the diameter expansion speed and the moving distance of the inner peripheral mold 42 can be changed. The moving speed of the outer peripheral mold 41 may be the same as or different from the moving speed of the inner peripheral mold 42. The movement distance of the outer peripheral mold 41 may be the same as or different from the movement distance of the inner peripheral mold 42.
The moving speed of the outer peripheral mold 41 and the inner peripheral mold 42 may be always constant from the start of molding to the end of molding. However, in order to shorten the molding time, the molding start is made faster than the latter half of molding. It is desirable. The movement speed of the outer peripheral mold 41 and the inner peripheral mold 42 may be faster in the latter half of the molding than in the first half of the molding, but since the molding requires less force than the latter half of the molding. It is desirable that the beginning of molding be faster than the latter half of molding.

In the rim forming step, the maximum value of the diameter expansion of the element ring 20 is set larger than the maximum value of the diameter reduction of the element ring 20. This is to suppress the occurrence of buckling in the reduced diameter portion and its vicinity due to the reduced diameter. The diameter reduction rate from the elemental ring 20 is about 5% or within 5% in the most diameter-reduced part, and the diameter expansion rate from the elemental ring 20 is about 10% or more than 10% in the most diameter-expanded part. It is desirable that Further, it is desirable that the ratio of the diameter expansion ratio to the diameter reduction ratio from the element ring 20 is 1: 2.8 or more.

The outer peripheral die 41 is integrated over the entire length in the axial direction (hereinafter also simply referred to as the axial direction) of the element ring 20 (rough forming ring 40). However, as shown in FIG. 11, the outer peripheral mold 41 may be a split mold (axial split mold) that is split into at least two in the axial direction. The number of divisions in the axial direction of the outer peripheral mold 41 may be two, three, or four or more. In addition, in FIG. 11, the case where the outer periphery type | mold 41 is divided | segmented into 3 pieces is shown. When the outer periphery mold | type 41 is an axial direction division | segmentation type | mold, the moving speed and moving distance to the radial direction of each type | mold of an axial direction may each differ.

The inner circumferential mold 42 may be integrated over the entire length in the axial direction, or may be a divided mold (axially divided mold) divided into at least two. The number of divisions in the axial direction of the inner peripheral mold 42 may be two, three, or four or more. In the illustrated example of the present invention, the inner peripheral mold 42 is divided into two parts. When the inner peripheral mold 42 is an axially divided mold, the moving speed and moving distance in the radial direction of each mold in the axial direction may be different from each other.

As shown in FIG. 11, when the number of divisions in the axial direction of the outer peripheral mold 41 is three and the number of divisions in the axial direction of the inner peripheral mold 42 is two, the outer peripheral mold 41 has the other end in the axial direction. The first, second, and third outer molds 41a, 41b, and 41c are provided in this order. The inner peripheral mold 42 includes first and second inner molds 42a and 42b in order from one axial end to the other end.
Further, when the number of divisions in the axial direction of the outer peripheral die 41 is three and the number of divisions in the axial direction of the inner peripheral die 42 is two, the rim forming step includes the following configuration.
First, the first and third outer molds 41a and 41c and / or the first and second inner molds 42a and 42b are moved with respect to the element ring 20, and the first and third outer molds 41a and 41c The axially opposite ends 21 and 21 of the element ring 20 are sandwiched between the first and second inner molds 42a and 42b.
Next, the second outer mold 41b is formed with the first and second outer molds 41a and 41c and the first and second inner molds 42a and 42b sandwiching the axial ends 21 and 21 of the element ring 20. Is moved (reduced in diameter) relative to the elemental ring 20 to reduce the diameter of the part of the elemental ring 20 that becomes the drop portion 30d of the rim 30.
Next, the first and second inner molds 42a and 42b are moved (expanded) with respect to the element ring 20 to form at least the first flange part 10a and the second flange part 10g of the rim 30. Increase the diameter of the part. The diameter reduction of the part of the element ring 20 that becomes the drop part 30d and the diameter expansion of the part of the element ring 20 that becomes the first flange part 10a and the second flange part 10g may be performed simultaneously.

At least one of the outer peripheral mold 41 and the inner peripheral mold 42 may be provided with a radially retracted portion 43 as shown in FIG. In the part of the mold for reducing the diameter of the elemental ring 20 such as the part of the elemental ring 20 that becomes the drop part 30d, the retracted part 43 is provided in the inner peripheral mold 42, and the first flange part 10a and the second flange part In the part of the mold that expands the diameter of the elemental ring 20 like the part of the elemental ring 20 that becomes 10 g, the receding portion 43 is provided in the outer peripheral mold 41. FIG. 12 shows a case where the radially retracted portion 43 is provided only on the inner peripheral mold 42.
The radial retreating portion 43 is formed on either the outer peripheral die 41 or the inner peripheral die 42 at the corresponding positions of the outer peripheral die 41 and the inner peripheral die 42 in the axial direction (the same position in the axial direction). In a state in which the forming ring 40) is pressed and formed by the outer peripheral die 41 and the inner peripheral die 42, the forming ring 40) is provided so as to recede in the direction away from the formed rough forming ring 40 and the formed rim 30 in the radial direction. As shown in FIG. 13, a retreating portion 43 is provided in the radial direction on the inner peripheral mold 42 at a position corresponding to the portion of the element ring 20 that becomes the drop portion 30d, and the first flange portion 10a and the second flange portion 10g A receding portion 43 may be provided in the radial direction on the outer peripheral die 41 at a position corresponding to the portion of the element ring 20. It is possible to suppress an excessive load from being applied to both molds 41 and 42 by the radially retracted portion 43. Therefore, the molding force can be reduced.

  As shown in FIG. 10, the press machine 50 includes a first wedge 51 arranged in a cylindrical shape for moving the outer peripheral die 41 in the radial direction, and a conical shape for moving the inner peripheral die 42 in the radial direction. The second wedge 52 is provided. By operating the press machine 50 and moving the first wedge 51 and the second wedge 52 in the axial direction, the outer peripheral die 41 and the inner peripheral die 42 are moved in the radial direction to form the element ring 20 into a rim shape. can do.

  As shown in FIG. 2, the rim forming step includes at least one rough forming step (preliminary forming step) and one finishing step. FIG. 2 shows a case where the rim forming process includes only two processes, one rough forming process and one finishing process.

In the rough forming process, as shown in FIGS. 2A and 2B, the diameter of the elemental ring 20 portion that becomes the drop portion 30 d of the rim 30 is reduced, and the diameter of the other elemental ring 20 part is increased.

In the rough forming step, as shown in FIGS. 3 and 4, the core ring 20 is reduced in diameter, and viewed from the axial direction of the core ring 20 on the side opposite to the drop bottom surface portion 30d1 of the first sidewall portion 30c. A recess 40a having a width (length) L smaller than a distance L ′ (see FIG. 6) between an end 30c1 and an end 30e1 on the opposite side of the drop bottom surface 30d1 of the second sidewall 30e. You may provide the process to shape | mold. The recess 40 a is continuously provided over the entire circumference of the rough forming ring 40. As shown in FIG. 3, only one recess 40a may be provided in the axial direction of the rough forming ring 40, or two recesses 40a may be provided as shown in FIG. It may be provided above. In addition, it is preferable to provide two or more recesses 40a in order to suppress deformation of the molded product (rim 30).
When a plurality of the recesses 40a are provided, the width L of each recess 40a may be constant or different. When a plurality of recesses 40a are provided, the total sum of the widths L of the recesses 40a is set to be smaller than the interval L ′ (see FIG. 6).

As shown in FIG. 5, the rough forming step may include a step of forming a flare portion 40 b by flaring at least the portion of the element ring 20 that becomes the first and second flange portions 10 a and 10 g. In the step of forming the flare portion 40b, it is desirable that the first and second bead sheet portions 30b and 30f and the hoop portion 30h are also flare-processed. This is because the first and second bead sheet portions 30b and 30f and the hump portion 30h can be formed by reducing the diameter of the flare portion 40b in a step subsequent to the step of forming the flare portion 40b. The flare portion 40 b is continuously provided over the entire circumference of the rough forming ring 40.

When the rough forming step includes both the step of forming the concave portion 40a shown in FIGS. 3 and 4 and the step of forming the flare portion 40b shown in FIG. 5, the step of forming the concave portion 40a forms the flare portion 40b. May be performed before the step of forming, may be performed after the step of forming the flare portion 40b, or may be performed simultaneously (in the same step) with the step of forming the flare portion 40b.

In the finishing step, as shown in FIGS. 2C and 2D, the rough forming ring 40 after the rough forming is formed into a rim shape. 7 to 13, the structure and operation are the same in the rough forming process and the finishing process, although the mold shapes are different.

The manufacturing method of the rim 30 according to the embodiment of the present invention may have a rim shaping step after the rim shaping step, as shown in FIG. The rim shaping process is a process for improving the roundness of the rim 30.
In the rim shaping step, the shaping mold 60 having the conical part 61 is moved in the axial direction of the rim 30, and at least a part of the rim 30 in the axial direction is pushed and expanded in the radial direction by the conical part 61 to shape the rim 30. In the rim shaping step, it is desirable to push the first bead seat portion 30b and the second bead seat portion 30f, which are portions to which tires (not shown) are attached, in the radial direction.
In the rim shaping step, when the rim 30 is pushed out in the radial direction by the shaping die 60, at least a part of the rim 30 in the axial direction is radially reduced by a roll (not shown) arranged on the outer peripheral side of the rim 30. The rim 30 may be shaped. Further, instead of shaping by the shaping mold 60 or in addition to shaping by the shaping mold 60, the rim 30 may be shaped by roll forming at least one stage.

Next, the operation of the embodiment of the present invention will be described.
Since the rim forming step is performed by pressing, the rim can be formed by using a general-purpose press 50, the outer peripheral die 41, and the inner peripheral die 42.

Since the rectangular steel plate 10 is wound into a cylindrical shape and both ends of the winding are welded to each other to form the elemental ring 20 and the rim forming step for making the elemental ring 20 into a rim shape, The rim 30 can be manufactured using the flat plate. Therefore, since it is not necessary to use a circular flat plate, waste of material can be suppressed compared to the case of using a circular flat plate. Further, the rim 30 can be easily formed.

Since the rim forming step includes at least one rough forming step and a finishing step, the rim 30 can be stably formed as compared with the case where the rough forming step is not provided.

By using the outer peripheral die 41 divided in the circumferential direction and the inner peripheral die 42 divided in the circumferential direction, the rim 30 can be molded with high accuracy.
Further, the rim 30 can be accurately formed by considering the phase and the number of divisions of the outer peripheral die 41 divided in the circumferential direction and the inner peripheral die 42 divided in the circumferential direction.

In the rim forming process, each of the movement speed and stroke of the outer peripheral mold 41 and each of the movement speed and stroke of the inner peripheral mold 42 are adjusted, thereby suppressing the occurrence of shrinkage and wrinkles. Thus, the rim 30 can be molded with high accuracy.

In the rim forming step, the maximum value of the diameter expansion of the element ring 20 is larger than the maximum value of the diameter reduction of the element ring 20, so that buckling occurs in the diameter-reduced portion of the element ring 20. The rim 30 with good quality can be molded.

Since the rim shaping step of shaping the rim 30 by moving the shaping die 60 having the conical portion 61 in the rim axial direction after the rim shaping step, the roundness of the rim 30 can be improved.

  In the rim forming process, both the diameter expansion and the diameter reduction of the element ring 20 are performed, so that the element ring 20 is buckled, compared to the case where the element ring 20 is only expanded or only the diameter is reduced to form the rim 30. The occurrence of defects such as cracks and constriction can be suppressed.

Since the rough forming step includes a step of forming the recess 40a by reducing the diameter of the element ring 20, the risk of buckling in the portion of the element ring 20 where the diameter is reduced can be greatly suppressed, and the quality can be improved more efficiently. A good rim 30 can be formed effectively.

DESCRIPTION OF SYMBOLS 10 Steel plate 11 Band-shaped member 12 Welding part 20 Elementary ring 30 Rim 30a 1st flange part 30b 1st bead sheet part 30c 1st side wall part 30d Drop part 30d1 Drop bottom face part 30e 2nd side wall part 30f 2nd Bead sheet portion 30g second flange portion 30h hump portion 40 rough forming ring 40a concave portion 40b flare portion 41 outer peripheral die 42 inner peripheral die 43 radial retreating portion 50 press machine 51 first wedge 52 second wedge 60 shaping die 61 Conical part

Claims (4)

An element manufacturing process for manufacturing an elemental ring by winding a rectangular steel plate into a cylindrical shape and welding both ends of the winding to each other;
An outer peripheral mold divided in the circumferential direction and an inner peripheral mold are moved with respect to the elemental ring to reduce the diameter of the elemental ring by the outer peripheral mold and the diameter expansion of the elemental ring by the inner peripheral mold. A rim forming step performed by pressing, wherein the element ring is formed into a rim shape;
Have
In the rim forming step, the vehicle wheel rim manufacturing method is such that the maximum value of the diameter expansion of the elemental ring is larger than the maximum value of the diameter reduction of the elemental ring.   The vehicle rim manufacturing method according to claim 1, wherein the rim forming step includes at least one rough forming step and a finishing step. 3. The vehicle wheel rim according to claim 1, wherein in the rim forming step, the movement speed and movement distance of the outer peripheral mold and the movement speed and movement distance of the inner peripheral mold are adjusted respectively. Manufacturing method . In the rim forming step, the base ring is reduced in diameter to form a drop bottom surface portion of the wheel rim and at least a part of the first and second sidewall portions,
In the rough forming step, the diameter of the elemental ring is reduced, and the end part of the first sidewall part opposite to the drop bottom part in the axial direction of the elemental ring and the second sidewall part The manufacturing method of the wheel rim for vehicles of Claim 2 provided with the process of shape | molding a recessed part with a width | variety smaller than the space | interval with the edge part on the opposite side to the said drop bottom face part.

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