JP3131822B2 - Finishing method for cast wheels - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel of an automobile or a motorcycle, and more particularly to a cast wheel in which a hub and a rim and spokes connecting them are integrally formed by casting, and a method of finishing the same.

[0002]

2. Description of the Related Art In general, cast wheels have been used in many motorcycles in recent years because they have a large degree of freedom in design and do not require a spoke assembling process. However, the rim of the wheel has a circumferential groove for fitting the tire that is open toward the outer periphery. Therefore, when casting the rim, it cannot be cast using a simple split mold, and it is divided into four or more. Required complex molds. In addition, the part where the tire of the rim is fitted needs a finished surface with excellent surface roughness to prevent air leakage, so it can not be a product until casting, and forged on the rim of the cast wheel material A finishing method has been adopted in which the structure is densified by processing, or a cutting process is performed without forming a forging step to form a tire fitting surface.

[0003] On the other hand, a hub and a rim are separately formed, and a hub and a rim are connected by spokes made of a steel wire, or a spoke is welded to a disc instead of being assembled. There, the wheel rim is plastically worked. That is, a steel strip as a raw material is formed by rolling, then cut to a predetermined length, and butt-welded at both ends to form an annular shape.

[0004]

As described above, since the rim portion of the conventional cast wheel is finished by cutting, it takes a long time to improve the surface roughness. There was a problem that the yield was low and the productivity of the wheels was significantly reduced. Further, there is a problem that the mechanical strength is reduced because the surface portion hardened by casting is cut off by the cutting. In addition, it was also known that the rim of the wheel was manufactured by plastic working, but conventionally, since it was simply adopted for manufacturing convenience, the hub, spokes and rim were separately manufactured and assembled by welding and the like. This requires an assembling process in addition to the molding process, so that the manufacturing cost rises, and a configuration for connecting a hub and the like is indispensable.

[0005]

An object of the present invention is to provide a rim portion of a wheel material in which a hub, a rim, and spokes for connecting the hub and the rim are integrally cast. It is supported by a mold that is the reverse of the inner surface of the rim, and the mold is rotated.It has an almost soloban bead shape with a large diameter at the center and a small diameter at both sides from the outside. Press the rotary die to make a cut in the center of the casting material in the width direction, move the rotary die from there to the left and right sides, flow the material outward, expand the cut, and expand the bead support. , And a lug extending from the bead support portion in the outer peripheral direction.

[0006]

The hub, spokes and rim are integrally formed by casting, and they are connected without requiring a mechanical or metallurgical bonding step. The rim portion is formed by plastic working to have a surface roughness enough to fit a tire directly thereon, and the material is forged to improve mechanical properties. The cast wheel material has a thicker rim shape at the center and a thinner outer portion in the width direction, and can be cast by a relatively simple two-piece casting mold. Since the rotation of the wheel material is transmitted to the rotating die,
The rotating dies are rotated.The contact point between the material and the rotating dies is constantly changed by being pressed against the wheel material.The contact area between the wheel material and the rotating dies is small.
There is little friction between them, and a relatively small pressing force gives effective deformation to the wheel blank.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In the figure, reference numeral 10 denotes a completed cast wheel. The cast wheel 10 has a hub 12 with an axle hole 13 and a diameter of about 450 mm.
For a motorcycle having the tire fitting groove 21 of the rim 2
0 and the spokes 30 connecting them are integrally formed metallurgically. In this embodiment, since the configurations of the hub 12 and the spokes 30 are not much different from those of the conventional one, detailed description will be omitted.

[0008] In the present invention, the tire fitting groove 21 located on the outer surface of the rim 20 is, as shown in FIG.
A base 22 connected to the spokes 30 is connected to the center in the width direction of the wheel. The base portion 22 is formed by plastic working with the fine structure. Also, the base part 2
2 has a substantially U-shaped cross-section that opens in the outer peripheral direction, and has a highly rigid connection structure with the spoke 30.
A bead support portion 23 for supporting a bead of a tire is provided continuously outside the left and right sides of the base portion 22 in the width direction. The bead supporting portion 23 includes a reinforcing rib 25 formed between the base portion 22 and the ear portion 2 extending from the outer end to the outer peripheral direction.
The structure is reinforced from both sides by two ribs 4 and 4 to withstand the strong tension of the tire bead. Rim 20
In addition, a central rib 26 located at the center of the base portion 22 in the inner peripheral portion and a side rib 27 integrally formed with the ear portion 24 are formed so as to protrude in the centripetal direction. Thus, the rim 20 is formed to be relatively thin and uniform in thickness from the base portion 22 to the side, is made lightweight, and has high rigidity.

Next, the casting wheel 1 having such a configuration will be described.
0 will be described. The production of the cast wheel 10 starts with a wheel blank 15 shown in FIG. 2 which is obtained by casting an aluminum alloy by gravity casting. Wheel material 15
The rim portion 15a is thick at the center in the width direction and thin at the sides. For this reason, casting is possible with a left-right split mold D indicated by a virtual line. The wheel blank 15 thus obtained is plastically worked by a spinning machine as described later.

[0010] As shown in FIG.
It has a bed like a lathe, a rotating main shaft, and a saddle slidably supported on the bed (both not shown). A mold E supported on the main shaft and a pivot 31 are freely rotatable. And a support frame 33 for supporting these are fixed on the saddle.
The rotary die 32 has a substantially abacus shape with a large diameter at the center and a small diameter at the outside in the width direction, and the supporting frame 33 supporting the rotary die 32 is in the axial direction together with the saddle (in the horizontal direction in the figure).
In addition, the rim 20 is controlled by a numerical control device (not shown) to advance and retreat toward the axis line CL. Specifically, the rim 20 moves along the contour of the tire fitting groove 21. It has become.

In order to process the wheel blank 15 by the above-mentioned apparatus, first, the wheel blank 15 is attached to a mold E as shown in FIG. At this time, a small gap C is left in the radial direction between the outer peripheral surface of the mold E and the rim portion 15a of the wheel material 15. Next, the wheel blank 15 is rotated together with the mold E at a high speed of 200 to 300 rpm. At this time, the peripheral speed of the rotary die 32 rotates with the rotation of the wheel material 15 and becomes about 350 m / min. In this state, in FIG.
As shown by the imaginary line, the rotary die 32 is pushed into the widthwise central portion of the rim portion 15a with a pressing force of about 20t to divide the material into right and left. When this step reaches the end and the rotary die 32 reaches a predetermined depth, the rim portion 15a is pressed against the outer surface of the mold E, and at the same time the gap C disappears,
A part thereof is pushed into the space for the central rib 26 provided in the mold E, and the central rib 26 is formed.

The fact that the rotating die 32 is in the shape of a soroban bead or that the rotating die 32 is formed means that the contact point between the wheel material 15 and the rotating die 32 constantly changes, so that the force required to deform the wheel material 15 is changed. Requires less. The small diameter of the rotary die 32 and the small contact area with the wheel material 15 are also effective in reducing friction and facilitating molding. That is, as a result of reducing the friction between them, the wheel material is effectively deformed with a small pressing force. In this embodiment, since the heat generated by the friction is not small, lubricating oil and a lubricating material are supplied as necessary and pushed into the wheel material 15.

Next, the rotary die 32 is moved outward from the center in the width direction. At this time, the rotary die 32 moves with respect to the surface corresponding to the base portion 22, the bead support portion 23, or the ear portion 24 formed on the mold E while leaving a gap corresponding to the thickness of the rim 20. The wheel blank 15 on the side surface of the rotary die 32 is pressed against the outer surface of the mold E, and at the same time, the wheel blank 15 is extended outward. Thus, one side of the rim 20 is formed. Similarly, the rotary die 32 is moved to the opposite side, and the rim 20 is completed by processing the remaining portion. The cast wheel 10 is mounted on the rim 2
When 0 is completed, a valve hole is drilled in the rim 20,
At the same time, the axle hole 13, the mounting hole and the like formed in the hub 12 are machined using the rim 20 as a working standard to complete the product.

The rim 20 of the cast wheel 10 thus obtained is processed by the rotating dies 32 so as to have a smooth surface and a fine metal structure to improve mechanical properties. Also, since molding is not based on cutting,
Auxiliary work such as grinding of a cutting tool is not required, and chips are not generated at the time of machining, so that the material yield is improved.

[0015]

According to the present invention, the rim is formed by a working process, so that the surface roughness of the product is improved, the wear of the tire is reduced, and since no cutting chips are generated, the material yield is excellent and the mechanical strength is high. . Furthermore, despite the fact that the rim is plastically worked, it is metallurgically integrated with the spokes formed by the casting method and does not require any means for joining, so that assembly is simple and productivity is good. Then, the annular rim material cast at the tip of the spoke is stretched laterally from the center to the left and right along the mold, and is molded.Therefore, the rim is finished to the product dimensions without generating chips, and the material is finished. There is no waste. Also, a large machine such as a press machine is not required for molding. And so on.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which wheels are products, (a) is a front view viewed from an axle direction, and (b) is a BB cross-sectional view thereof.

FIG. 2 is a cross-sectional view showing a manufacturing process and showing a casting material as a material of a casting wheel.

FIG. 3 is a sectional view corresponding to FIG. 2, showing a state in which a casting material is attached to a mold.

FIG. 4 is a sectional view corresponding to FIG. 3 showing a shape during molding.

FIG. 5 is a side view corresponding to FIG. 3 showing a shape at the end of molding.

[Explanation of symbols]

10 ··· Cast wheel 12 ··· Hub 13 ··· Axle hole 15 ··· Wheel material 15a ··· Rim 20 ··· Rim 21 ··· Tire fitting groove 22 · ... Base part 23 ... Bead support part 24 ... Ear part 25 ... Reinforcement rib 26 ... Central rib 27 ... Side rib 30 ... Spoke 31 ··· Support shaft 32 ··· Rotating die 33 ··· Support frame C ··· Clearance D ··· Mold E ··· Mold CL ····· Axis line

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60B 1/00-3/06 B21H 1/04

Claims (1)

(57) [Claims] A rim portion of a wheel material in which a hub, a rim, and spokes connecting the hub and the rim are integrally cast, is formed into an annular shape having a thick central portion in the width direction and a thin lateral portion. Support the mold in the opposite shape of the mold, and rotate the mold.Press the rotating die, which has a large diameter at the center and a small diameter at both sides, from the outside, and press it against the casting material. A notch is made at the center in the width direction, and then the rotating die is moved to the left and right sides, and the cut is pushed out by flowing the material outward, and the bead support portion, and the outer periphery from the bead support portion Finishing method for cast wheels to form ears extending in the direction.