JP2002114002A - Light alloy wheel for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light wheel at a low cost by forming a novel shape in comparison with a conventional one with the predetermined means. SOLUTION: This light alloy wheel for vehicle has a disk part including a hub part and a design part, and has a rim part. The disk part is provided with a spoke part formed by mold casting at the design part thereof, and at least one part of a cast part in a back surface of the spoke part is formed at 5.0 degree or less in inclination of a taper part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light alloy wheel for a vehicle using a low-pressure casting and gravity casting mold, in which a cast-out portion is provided more efficiently on a spoke portion and a back surface of a hub portion than before. In particular, even in the case where the width of the spoke portion is small, the weight can be reduced more than before.

[0002]

2. Description of the Related Art Road wheels of automobiles, which are one type of vehicle wheels, have various materials and structures. For the purpose of reducing the weight and improving the appearance and design of automobiles, iron and aluminum alloys are used. Conversion to light alloys such as magnesium alloys and titanium alloys is progressing, and the proportion of aluminum wheels made of aluminum alloys is increasing.

As shown in FIG. 10, a light alloy wheel 30 generally has a disk portion including a thick hub portion 31 attached to an axle by bolts and nuts, a design portion 32 in which a thick portion and a thin portion are mixed, It comprises a thin rim 33 to which a tire is attached. The rim portion 33 includes a front flange portion, a rear flange portion, a cross portion where the rim portion and the disk portion intersect, and a rim center portion. The design part 32 is provided with a spoke part 34 and a design hole 35. The hub portion is provided with a bolt hole concave portion 36 for fixing to the vehicle body with a bolt.

[0004] Wheels affect the appearance of a vehicle and are produced in various shapes. Broadly speaking, there are spoke type, dish type, fin type and mesh type. The spoke type is designed such that 3 to 10 spokes extend from the hub portion and are connected to the rim portion, and the spokes are mainly used. In the dish type, a gentle surface is formed in a much wider area of the hub portion than in the spoke type, and the center of the design portion connected to the rim portion by shorter spokes is substantially disc-shaped. The fin type belongs to the spoke type, but is characterized by a relatively large number of spokes and a thin point. Also, the mesh type has a large number of spokes and is elongated narrowly, but the spokes are meshed like a mesh between the hub portion and the rim portion. Each specification has various forms.

FIG. 1 is a view showing the back side of the design surface shown in FIG. In the figure, parts corresponding to those in FIG. 10 are denoted by the same reference numerals. As described above, the spoke portions and the hub portions which are convex in design surface are provided with the cast-out portions 37 and 38 in order to reduce the weight. Usually, an upper die is provided in this cast-out portion. However, it has been difficult to form the cast-out portion in the best shape even if it is intended to achieve both strength and weight reduction.

[0006]

In the cast-out portion, a taper portion inclination for releasing from the mold is provided. However, conventionally, in mass production, it is difficult to reduce the taper portion inclination. Unless it is about 8 °, mold release is poor. Therefore, when the cast portion is provided in the hub portion and the spoke portion with a certain inclination of the tapered portion, in addition to the cast portion 50 which is required to have a minimum strength as shown in FIG. However, if the mold is designed in consideration of the inclination θ ′ of the tapered portion, the cast portion 51 that can be reduced in weight remains at the casting stage, and the weight cannot be further reduced without post-processing. In particular, it is difficult to reduce the weight of the thin spoke portion. Accordingly, an object of the present invention is to provide an inexpensive light alloy wheel for a vehicle, which can be formed into a shape which has not existed in the past by using a predetermined means, and which can achieve weight reduction even in various design portions.

[0007]

The light alloy wheel for a vehicle according to the present invention can be obtained for the first time by controlling the opening of the mold and arranging and pouring a plurality of gates, which is not performed as a conventional wheel manufacturing method. It is a thing. That is, a light alloy wheel for a vehicle having a disc portion including a hub portion and a design portion and a rim portion, wherein the disc portion has a spoke portion formed by die casting in the design portion, and the spoke portion or the hub. At least one part of the back surface of the portion has a tapered portion inclination of 5.0 ° or less at the tapered portion. Further, it is possible to make the taper portion inclination of 5.0 ° or less in a portion of 30% or more, or even 50% or more of the entire taper portion. Since the width is narrow and a deep cast-out portion can be formed, the weight can be reduced not only in the spoke-shaped wheel shown in FIG. 2 but also in the mesh-shaped or fin-shaped thin spoke portion shown in FIG.

Thus, even if the back surface of the design portion is formed by one mold, it is possible to form a cast-out portion having a depth five times or more the width. The inclination of the tapered portion is 4.5.
° or even 4.0 ° or less.

According to the present invention, of a light alloy wheel for a vehicle having a disk portion including a hub portion and a design portion and a rim portion, only the disk portion is cast by a mold, and the other rim portion is manufactured by another manufacturing method. Not only a two-piece wheel or a three-piece wheel bonded to a wheel, but also a light alloy wheel for a vehicle which is die-cast as a one-piece wheel in which the mold is hardly filled with molten metal can be used.

In the present invention, the cast-out portion is, as shown in FIGS. 5 and 6, a concave portion formed on the back side of the hub portion and the design portion for reducing the weight. The hub portion is a thick portion formed near the center of the design surface. Further, the spoke portion refers to a connecting portion that bridges between the hub portion and the rim portion. The inclination of the tapered portion is the portion of θ shown in FIGS. For example, as shown in FIG. 5, when the cast portion is provided in the spoke portion 34 and the inclination of the tapered portion of the cast portion is constant up to the back side of the design surface, the taper portion inclination θ is equal to the axial direction (A) of the wheel. This is the angle made by the tapered portion 40 of the punched portion.
Also, as shown in FIG. 6, when the cross-sectional shape of the cast-out portion is such that the taper portion has a different curvature depending on the location, it is the angle at the portion where the angle with the axial direction of the wheel becomes the smallest.

Further, the definition of “up to% or more of the entire tapered portion” does not indicate% with respect to the area of the tapered portion. It shows the ratio of the length of the portion where the taper portion inclination of 5 ° or less exists to the length of the contour of the taper portion inclination viewed from the back side of the design surface. For example, in FIG. 1, a plurality of Y-shaped spokes are provided on the design surface. However, a tapered portion inclination larger than 5 ° at the cast portion on the rim side than the Y-shaped branched portion, and the remaining branching It is assumed that only the hub portion side is formed with a taper portion inclination of 5 ° or less than the tapered portion. If the sum of the contours of the cast-out part on the rim part side with respect to the Y-shaped branched part is 240 mm and the remaining hub part side is 72 mm, 240 / (240 + 72) = 0.969,
67.9% are portions having a taper portion inclination of 5 ° or less.

[0012] When the cast-out portion is provided larger than usual, the cavity in the mold is reduced, and the flowability of the molten metal is deteriorated. In the side gate method in which the gate is provided only in the rim portion, or in the center gate method in which the gate is provided only in the disk portion, since the flow of the molten metal is suppressed in the above-described portion, the molding state is deteriorated and the casting cycle is likely to be delayed, By providing a plurality of gates on the rim portion and the disk portion, it is possible to form a thin and lightweight wheel in which the inclination of the tapered portion of the cast-out portion is small. Further, the inclination of the tapered portion can be set to 4.0 or less, and further, 3.5 ° or less.

When the solidified wheel is taken out of the mold as well as the gate for carrying out the present invention, strict drive control of the mold is required. When opening the lower mold or the upper mold that forms the disk part, it is preferable to move the movable platen using a parallel control drive device that synchronously pushes up the movable platen at three or more locations. A synchronous piston is provided on the upper platen, the upper plate is pushed up, and the upper plate located at the lowermost position is 20 to 30 mm.
What is necessary is just to move in parallel to the height of about. Alternatively, provide three or more synchronous hydraulic cylinders on the lower platen,
The movable platen may be directly pushed up. If the number is less than two, the movable platen is likely to be tilted and galling occurs, so that it is difficult to produce a product having a small tapered portion tilt.

In a conventional wheel casting machine, the movable platen is simply pulled up by one hydraulic cylinder, and the mold is simply opened. However, in casting a wheel, a holding furnace is provided near the lower platen, and in such a configuration, the lower platen easily expands thermally. Because the dimensional difference due to thermal expansion between the upper platen and the lower platen is different, the inner diameter of the guide and the outer diameter of the guide post should be 0.3 to
It is necessary to have a gap of about 0.5 mm. However, this gap causes a phenomenon that the movable platen constantly rises while tilting somewhere. 5. In the tapered part of the cast-out part
If the inclination of the movable platen is within the allowable range as long as the inclination of the movable platen is 0 to 8.0 °, the product can be released without deteriorating the shape of the molded product. In a product having a taper portion inclination of 5 ° or less, galling is likely to occur at a spoke portion or a cast portion of a hub portion. Also, when removing the wheel from the upper mold, the movable platen approaches the pusher pin that is usually fixed to the upper mold platen,
The wheel is pushed out from above and the pin is pushed out. At the time of mold release, the product has a temperature of 400 to 450 ° C and low strength. Especially when the design surface has a complicated shape, even if the wheel can be released from the lower die, it is difficult to release the wheel from the upper die later, and the strength is weak in the pulling direction, Failure to raise vertically vertically will result in damage to the upper mold and deformation of the design. Therefore, detailed consideration of the movable platen provided with the upper mold at the time of release is a very important technique. In order to raise the movable platen by strict control, it is necessary to perform parallel movement control for simultaneously pushing up three or more places on the upper die or the movable platen fixed to the upper die with the same amount of movement. A four cylinder vertical cylinder system is particularly effective. The cylinder may be driven using a current control valve or a servo valve.

The upper mold generally pushes the lower mold with a 200 KN clamping force. Because it is about 10MPa in hydraulic pressure,
This 10 MPa is reduced to substantially 0 MPa at a speed of less than 0.01 second.
When it is dropped, the deformation due to the stress applied to the casting machine is released at once, and a surge pressure is generated in the hydraulic circuit, which causes the entire casting machine to vibrate and the movable platen moves parallel to the upper platen. The movable platen moves laterally with respect to the upper platen, making it easier to cause galling behind the design surface. The time required for the actual valve to be fully opened is about 0.02 seconds, but the time when the mold clamping force becomes 0 MPa is about half of that time. Therefore, the mold clamping force is removed over a long period of time of 0.05 seconds or more, more preferably 0.10 seconds or more, so that the impact of the casting machine due to rapid oil pressure reduction is relieved, resulting in a design without galling. The surface can be shaped.

It is preferable to increase the clamping force so that unnecessary vibration and stress are not applied during clamping.
If the mold is suddenly clamped, vibration will occur in the entire casting record. The total weight of the movable platen and the lower mold is close to 3 to 4 tons, and a stress distortion of about 1 mm is generated in the upper mold platen and the lower mold platen in the vertical direction. Also, when closing the mold,
Since it also affects the parallel direction, it is preferable to perform mold clamping at a predetermined speed in order to manufacture an aluminum wheel with a small gradient of the tapered portion of the cast portion.

[0017]

(Embodiment 1) Hereinafter, the details of the present invention will be described with reference to the drawings. FIG. 3 is an example in which a light alloy wheel for a vehicle according to the present invention is cast, and is a diagram schematically showing equipment in a case where an aluminum alloy wheel is cast by ordinary low pressure casting. A holding furnace 2 is provided in the closed container 1, and a lower platen 3 is mounted on the closed container 1 to seal the closed container 1. The lower die platen 3 is provided with a stalk 4b for replenishing the molten metal 5 of the aluminum alloy into the mold at the center thereof, and the lower end of the stalk 4b is immersed in the molten metal 5 in the holding furnace 2. The upper end of the stalk 4b is connected to the sprue portion 7 of the mold via the sprue bush 6 fitted into the lower mold platen 3 and the lower mold 8 of the mold. The molten metal poured through the stalk 4b flows into the lower mold 8 and is poured into the cavity forming the hub of the wheel.

The lower die 8 of the die is attached to the lower platen 3. The lower die 8 is a fixed die, and is a surface on which a design portion is formed in the wheel. In this embodiment, the inclination of the tapered portion of the cast-out portion was 3.5 °, and the sectional shape of the spoke portion was as shown in FIG. The thickness T1 was 30 mm. Both lateral sides are laterally movable dies 10, which form the outer peripheral surface of the rim portion of the wheel. The upper mold 12 of the mold is attached to a movable platen 14. The upper die 12 is a so-called movable die, and forms a back surface of a design portion for attaching a wheel to a vehicle and an inner peripheral surface of a rim portion. The movable platen 14 is fixed to a guide post 15, and the guide post 15 can move up and down along a guide 16 provided on the upper platen 13. The upper end of the guide post 15 is fixed to the upper plate 17, and the hydraulic cylinder 21 provided on the upper platen moves the upper plate, and the movable platen 14 and the upper die 12 move up and down following the movement. In FIG. 2, the position where the upper plate 17 has reached the lowermost end is indicated by a broken line. The lowermost position is the position when the upper mold 12 is clamped to the horizontal mold 10 and the lower mold 8.

The casting operation is performed according to the following procedure. Lower mold 8,
After closing the molds of the upper mold 12 and the horizontal mold 10, a pressurized gas of 0.02 to 0.05 MPa such as air or an inert gas is fed into the closed container 1 through the pressurized gas supply pipe 18. Due to the sent pressurized gas, the molten aluminum 5 kept at about 700 ° C. in the holding furnace 2 is pushed up through the stalk 4 to the cavity in the mold kept at 350 to 450 ° C. enter. The cavity portion of the mold is coated with a coating that combines heat retention and release. After about 2 to 3 minutes, the pressurization is stopped, the molten metal 5 in the unsolidified stalk 4 is returned to the holding furnace 2, and the molten metal in the mold is waited for solidification. When the solidification of the molten metal in the mold is completed and the temperature reaches the removal temperature of about 400 to 450 ° C, the mold is opened and the cast product (wheel) is placed on the upper mold.
Raise the upper mold with the mark. When the wheel has risen to some extent, the wheel is separated from the upper die by the push pins fixed to the upper die platen, and the wheel is taken out using the detachable arm 11. This cycle is repeated and the product is cast.

As shown in FIG. 7, the oil pressure gradually decreased over 0.20 seconds and did not give any vibration to the casting machine.
Furthermore, it was confirmed that the movable platen rises while maintaining the parallelism with respect to the upper platen with almost no inclination throughout. In addition, 20 light alloy wheels for vehicles of 5 ° or less were manufactured at 50% or more of the inclination of the tapered portion of the spoke portion and the cast portion of the hub portion, and observation was made to see if there was any galling or deformation in the design. . Generation of galling on the back side of the design surface in this shape was not confirmed, and a wheel having a good shape was obtained.

Example 2 A wheel for a vehicle was manufactured in the same manner as in Example 1 except that the casting machine shown in FIG. 4 was used. Unlike the first embodiment, a plurality of stokes 4a and 4c are provided, and the molten metal flows into the horizontal die 10 through the lower die 8 and is poured into a cavity for forming a rim portion of the wheel. The molten metal 5 poured from the stalks 4a and 4c is slightly angled from the direction toward the wheel axis of the cavity to suppress the flow of the molten metal so that the molten metal 5 can easily flow in the circumferential direction of the rim. Twenty light alloy wheels for vehicles were manufactured, and observations were made for galling and deformation on the back side of the design surface. However, generation of galling on the design surface was not confirmed, and a wheel having a good shape was obtained.

(Example 3) Casting was performed using a total of three stokes. One of them was poured into the cavity forming the hub portion of the wheel as in the first embodiment. Also,
The remaining two rods flow into the horizontal mold 10 as in the second embodiment, and are poured into the cavity for forming the rim of the wheel. In addition, the shape of the lower die is changed, and the inclination of the tapered portion is 3.
The angle was set to 5 ° and the sectional shape of the spoke portion was as shown in FIG. The thickness T1 is 30 mm or more, and the ceiling thickness is 5 mm.
Hereinafter, the minimum width w is set to 4.5 mm or less, and the taper portion inclination is set to 3.5 ° at a portion of 50% or more of the tapered portion of the spoke portion. Otherwise, 20 vehicle wheels were manufactured under the same casting conditions as in Example 1. FIG. 1 shows a drawing viewed from the back side of the design surface of the wheel. Generation of galling on the back side of the design surface in this shape was not confirmed, and a wheel having a good shape was obtained.

(Comparative Example 1) As a comparison, FIG. 8 shows the pressure applied to the descending hydraulic pressure when the descending hydraulic pressure is reduced from 10 MPa to 0 MPa at a speed of 0.01 second and the upper die is raised with respect to the lower die. The fluctuation and the displacement of the movable platen are shown. The casting method and the measuring method are the same as in the first embodiment.

As shown in FIG. 8, the oil pressure suddenly dropped, and thereafter a sharp change was repeated about five times. The change was settled about 0.1 seconds after the moment when the oil pressure was lowered. It was confirmed that the movable platen tilted due to the severe fluctuation, and ascended with respect to the lower mold. The maximum displacement of each of the four corners of the movable platen is a position raised by about 3 to 5 mm, and a displacement difference of about 1.5 mm is confirmed.
There was also a large displacement difference in subsequent ascents. Twenty light alloy wheels for a vehicle having the same shape as in Example 1 were manufactured, and observation was made for galling on the back side of the design surface. As a result, although there were some differences, generation of galling was confirmed in all the wheels, and the appearance was deteriorated.

(Embodiment 4) When opening the lower or upper die forming the disk portion, four synchronous pistons 20 are provided on the upper platen on the upper die platen, and the upper plate at the lowermost position is set to 20.
It was raised while maintaining parallelism to a height of about ３０30 mm. In addition, a guide pin having a height of about 20 mm was provided between the upper mold and the lower mold so as not to move in the horizontal direction. Others were manufactured similarly to the comparative example 1.

In the same manner as in Comparative Example 1, the descending hydraulic pressure was reduced from 10 MPa to 0 MPa in 0.01 second, and the pressure fluctuation and the displacement of the movable platen applied to the descending hydraulic pressure when the upper mold was raised with respect to the lower mold were measured. It was measured. As a result, the fluctuation of the hydraulic pressure was the same as that of Comparative Example 1, but the fluctuation of the movable platen showed an almost constant increasing tendency. Based on the control of the four synchronous pistons, 0.5 mm was obtained at the four measurement positions. It was confirmed that the movable platen rises while maintaining the parallelism with the variation within.

(Example 5) As in Example 3, low pressure casting was performed using a total of three stalks. In addition, the shapes of the lower mold and the upper mold were changed, and a spoke type aluminum wheel shown in FIG. 2 was integrally cast. The inclination of the tapered portion of the cast-out portion on the back surface of the hub portion was 3.5 °. Otherwise, 20 vehicle wheels were manufactured under the same casting conditions as in Example 1. Generation of galling on the back side of the design surface in this shape was not confirmed, and a wheel having a good shape was obtained.

[0028]

As described above, according to the present invention, it is possible to form a spoke portion and a hub portion having a small inclination of a tapered portion of a cast-out portion without casting. As a result, it is possible to manufacture a wheel that is lighter than a conventional wheel. In addition, there is also an effect that the life of the mold is improved because there is little damage to the upper mold and the lower mold, and it is possible to integrally cast a light alloy wheel for a vehicle that has never been lighter without processing the cast-out portion, It can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a front view of a disk portion of a wheel according to an embodiment of the present invention.

FIG. 2 is a front view of a disk portion of a wheel according to another embodiment of the present invention.

FIG. 3 is an example of a casting machine used in the present invention.

FIG. 4 is an example of another casting machine used in the present invention.

FIG. 5 is an embodiment showing a shape of a taper portion inclination.

FIG. 6 is an embodiment showing another shape of the taper portion inclination.

FIG. 7 is a diagram illustrating a change in hydraulic pressure and a movement amount of a platen when the mold is opened according to the embodiment.

FIG. 8 is a diagram showing a change in hydraulic pressure and a movement amount of a platen in a conventional mold opening.

FIG. 9 is a schematic diagram showing a relationship between a tapered portion inclination and a wall thickness of a cast-out portion.

FIG. 10 is a front view of a disk portion of a conventional wheel.

[Explanation of symbols]

1: Closed vessel, 2: Holding furnace, 3: Lower platen, 4: Stoke, 5: Molten, 6: Gate bush, 7: Gate section,
8: lower die, 9: guide pin, 10: horizontal type, 11: detachable arm, 12: upper die, 13: upper die platen, 14: movable platen, 15: guide post, 16: guide, 17: upper plate, 18 : Pressurized gas insertion tube, 20: 4 synchronous pistons,
21: Hydraulic cylinder, 30: Aluminum wheel, 31: Hub part, 32: Design part, 33: Rim part, 34: Spoke part, 35: Design hole, 36: Bolt hole concave part, 37: Cast-out part (Spoke part) , 38: Cast-out part (hub part), 3
9: Casting portion taper portion inclination, 50: Casting portion, 51: Lightweight casting portion

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanobu Taniguchi 5200 Mikajiri, Kumagaya-shi, Saitama Pref.

Claims (6)

[Claims] 1. A light alloy wheel for a vehicle having a disc portion including a hub portion and a design portion and a rim portion, wherein the disc portion has a spoke portion formed by die casting in the design portion, and the spoke portion has a spoke portion. A light alloy wheel for a vehicle, characterized in that at least one part of the cast-out part on the back surface of the part has a part whose inclination is 5.0 ° or less. 2. The taper portion inclination at the cast-out portion on the back surface of the spoke portion is 30% of the entire taper portion at the cast-out portion.
The light alloy wheel for a vehicle according to claim 1, wherein the angle is 5.0 ° or less in the above-mentioned portions. 3. The inclination of the tapered portion in the cast-out portion on the back surface of the spoke portion is 50% of the entire tapered portion in the cast-out portion.
The light alloy wheel for a vehicle according to claim 1, wherein the angle is 5.0 ° or less in the above-mentioned portions. 4. A wheel made of a light alloy for a vehicle having a disk portion including a hub portion and a design portion and a rim portion, wherein at least one portion of a tapered portion inclination at a cast-out portion on the back surface of the hub portion is 5.0. ° Light alloy wheels for vehicles, characterized by having the following parts. 5. The method according to claim 1, wherein the whole is integrally molded.
5. The light alloy wheel for a vehicle according to 4. 6. The method according to claim 1, which is manufactured by a low pressure casting method.
A light alloy wheel for a vehicle according to claim 1.