JP4730639B2 - Light alloy wheel for vehicle and die for casting - Google Patents

Description

【００２６】
（比較例１）
図２に記載の水冷機構５１のみに冷却水を流し、水冷機構５０には冷却水を流さず鋳造を行った。鋳造を２００〜３００サイクルほど行うと図２のボルト穴形成用凸部８１の周囲に溶湯の焼き付きが発生し、製品の不良成形となった。又、金型のメンテナンスに時間を費やさなければ成らなかった。ＤＡＳ値の測定値を表１に併記する。特にボルト穴近傍でのＤＡＳ値が本発明のものとは異り大きい。組織観察写真を図６に示す。
【００２７】
（実施例２）
また、別の下型の詳細な形態を図１に示す。図１と図２で同一の構造のものは同一符号で示す。図１に示すように下型８には冷却用の水冷機構５２、５１を内部に配置している。水冷機構５２は主にハブ部近傍を冷却するようにホイールのディスク面に形成されるボルト穴用凹部となるボルト穴形成用凸部８１内に凸方向に延出した空洞部５２ａが配置されている。前記空洞部５２ａの奥にまで冷却管５２ｂを挿入し、外部冷却管５２ｃからミストを供給し、空洞部内を冷却した。排出されたミストは凸部近傍を冷却した後、冷却管５２ｂと空洞部５２ａの間を介して戻り、連通部８３から下型外へ排出される。
【００２８】
【発明の効果】
以上に記述の如く、本発明によれば、下形のボルト穴形成用凹部に最適な冷却構造を内装したことで、従来よりもはるかに強度がよく、安全性の高いホイールを提供できた。また、離型性が良くなったことで溶湯をハブ部から注湯する法案においてもテーパ部傾きの少ないボルト穴用凹部を形成することが可能である。
また、本発明の金型を用いることでホイール離型時のカジリが発生しなくなり、作業効率の向上を計ることができた。
【図面の簡単な説明】
【図１】下型の冷却機構を示す断面図である。
【図２】別の下型の冷却機構を示す断面図である。
【図３】ボルト穴周辺の要部断面図である。
【図４】ホイールの断面形状を示す図である。
【図５】本発明のボルト穴近傍の金属組織写真である。
【図６】従来のセンターゲート法案でのボルト穴近傍の金属組織写真である。
【図７】本発明に用いた鋳造機の１例である。
【符号の説明】
１：密閉容器、２：保持炉、３：下型プラテン、４：ストーク、５：溶湯、６：湯口ブッシュ、７：湯口部、８：下型、９：ガイドピン、１０：横型、１１：脱着アーム、１２：上型、１３：上型プラテン、１４：可動プラテン、１５：ガイドポスト、１６：ガイド、１７：上板、１８：加圧気体挿入管、２０：４本同期ピストン、２１：油圧シリンダ、３０：アルミホイール、３１：ハブ部、３２：デザイン部、３３：リム部、３４：スポーク部、３５：意匠穴、３６：ボルト穴用凹部、３７：ボルト穴、３８：ハブ穴、３９ボルト接触部、４０：テーパ部傾き、４１：意匠面側、４２：天井肉厚、４３：鋳抜き部抜け勾配、４４：鋳抜き部、５０，５１：冷却機構、８１：ボルト穴形成用凸部、８２スポーク部金型[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle with a light alloy wheel that is particularly safe and highly designable. The present invention also relates to a casting mold for producing the light alloy wheel for a vehicle, particularly to a low pressure casting mold.
[0002]
[Prior art]
There are various materials and structures for automobile road wheels, which are one of the wheels for vehicles, but from iron to aluminum alloys, magnesium alloys and titanium alloys for the purpose of reducing the weight and improving the appearance and design of automobiles. Conversion to light alloys such as these is progressing, and the ratio of mounting aluminum wheels made of aluminum alloys is increasing.
[0003]
As shown in FIG. 4, generally, a light alloy wheel 30 includes a thick hub portion 31 attached to an axle by bolts and nuts, a disk portion including a design portion 32 in which a thick portion and a thin portion are mixed, and a tire. It is composed of a thin rim portion 33 to be worn. The rim portion 33 includes a front flange portion, a rear flange portion, an intersection where the rim portion and the disk portion intersect, and a rim center portion. The design part 32 is provided with a spoke part and a design hole. The hub portion 31 is provided with a bolt hole 34 for fixing to the vehicle body with a bolt.
[0004]
The wheel determines the appearance of the vehicle and is produced in various shapes. There are broadly classified types such as spoke type, dish type, fin type, and mesh type. Further, the periphery of the concave bolt hole recess formed around the bolt hole has various forms depending on the type and specification.
[0005]
The bolt hole portion formed at the bottom of the bolt hole recess is fixed to the vehicle body by bolting, and a load is applied to transmit the driving force to the tire. However, it is difficult to increase the thickness and strengthen the weight of the light alloy wheel that is required. Further, in the casting method, the vicinity of the hub portion often becomes the final solidified portion, and there is a problem that it is difficult to improve the strength because the cooling rate is slow, and there is still room for examination. Moreover, the metal mold | die which shape | molds the recessed part for bolt holes becomes convex shape, and the wear of the mold release material by molten metal is intense. This is particularly noticeable in the casting method in which molten metal is poured from the hub cavity. For this reason, it was necessary to rework the mold at all times, which led to deterioration in productivity. Furthermore, even when trying to make a bolt hole recess with a small taper slope, the mold could not be released from the mold and scratches such as galling were likely to remain.
[0006]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide a low-intensity wheel that is shaped with a high-strength, safety, and high-definition shape that has never been achieved before and that has a sharp feeling.
[0007]
[Means for Solving the Problems]
The light alloy wheel for a vehicle according to the present invention has been studied along with the above problems, and as a result, has been solved by providing an unprecedented cooling structure. In other words, the present invention is a light alloy wheel for a vehicle having a disc portion including a hub portion and a design portion and a rim portion, and a bolt provided on the hub portion based on a DAS value at an intersection of the rim portion and the disc portion. The DAS value near the hole is smaller. Also, a light alloy wheel for a vehicle having a disc portion including a hub portion and a design portion and a rim portion, in the vicinity of a bolt hole provided in the hub portion from a DAS value of an intersection portion of the rim portion and the disc portion. The DAS value is smaller, and at least a part of the DAS value near the bolt hole provided in the hub portion is less than 30 μm.
[0008]
As a feature seen in the vehicle wheel of the present invention, it is possible to increase the cooling rate of the hub portion as compared with the conventional one. As a result, the DAS value in the vicinity of the bolt hole and also in the hub portion is much smaller than the conventional one, and the strength can be improved. In addition, cooling in the vicinity of the center gate dramatically improves manufacturing problems, and eliminates galling between the mold and the casting wheel at the hub portion having a complicated shape. This eliminates scratches on the wheel surface during mold release and reduces the occurrence of defects. Further, the molten metal is not damaged by the molten metal in the convex mold portion that forms the concave portion for the bolt hole, and the production efficiency is improved. In the present invention, the DAS value in the vicinity of the bolt hole was measured at the shaded portion shown in FIG. In the figure, 34 is a bolt hole, and a nut inserted from a bolt hole recess 37 comes into contact with a bolt contact portion 39 to fix the vehicle body and the wheel. Reference numeral 38 denotes a hub hole machined to a predetermined dimension, and 36 denotes an end portion of the spoke portion. The gate is usually cast in a state where it is provided below the hub hole 38 in the figure.
[0009]
The advantages of the present technology are described from the viewpoint of the castability of the molten metal. The vicinity of the bolt hole of the hub portion is a portion that requires strength because it is caulked by a nut . In the bill of pouring molten metal only from the hub (center gate bill), the vicinity of the bolt hole is close to the pouring gate, so the cooling rate of the molten metal becomes slow and the strength tends to drop compared to other parts. In order to improve the strength of the entire surface of the disk portion, cooling near the hub portion, particularly near the bolt hole is particularly important.
[0010]
In the center gate bill, when this part is cooled, the molten metal at the hub part solidifies first, and the hot metal effect at the rim part tends to be insufficient, so it is important to set the mold cooling for other parts as appropriate. . It is also possible to use the side gate method in which a molten metal dam is provided in the cavity portion forming the rim portion and poured. In addition, even if cooling is performed in the vicinity of the hub, if the multi-gate aluminum wheel is cast integrally with a molten metal weir in each cavity that forms the hub and rim, cooling is performed in the vicinity of the hub. It is preferable to set the directional solidification with the effect of the hot water in combination with the mechanism. The effect of the hot water for preventing the sinkholes in the spokes can be achieved to some extent by the pressure from the dam (side gate) on the rim side. Therefore, even if a cooling mechanism is provided in the bolt hole, a casting cycle will not occur. Shortening and improving the strength at the hub can be performed in a well-balanced manner. Particularly in the vicinity of the bolt hole, the bolt is fastened and fixed to the vehicle body and needs strength. Since the cooling rate is fast, there is no problem even if the thickness is reduced to improve the strength around the bolt hole. In the cooling condition of the present invention, the molten metal feeder effect time on the disk portion is relatively short, so that it can be easily applied to a rim portion having a larger volume. Specifically, the wheel shape suitable for manufacturing is expressed by the weight ratio of the rim portion to the disc portion, and the rim portion: disk portion = 6: 4 or the rim portion occupies a higher ratio.
[0011]
In the present invention, the relationship between the DAS value at the intersection and the DAS value in the vicinity of the bolt hole is defined. The technical reason will be described. The comparison of the two DAS values examined which of the hot water from the rim side and the pouring gate at the center of the disc should be finally left. For example, in order to integrally cast a vehicle wheel with a thin spoke part by the multi-gate method, the hot water effect from the center of the disk is terminated early, and the remaining unsolidified part is directed by the hot water effect from the rim part. It was found that it is preferable for the casting of the wheel to be coagulated. As a result, the cooling of the disk portion that mainly controls the design with a complex shape can be accelerated, and the castability such as mixing of bubbles can be improved. As a result, even if coating treatment such as vapor deposition plating is performed, it can be processed without any problem in appearance. Therefore, it is preferable to cool the hub portion more preferentially than the rim portion where the side gate is provided. In the embodiment, the DAS value of the measuring portion (portion that gives the hot water effect from the hub portion side) shown in FIG. 3 close to the spoke portion in the bolt hole and the crossing portion (the hot water effect from the rim portion side is given to the spoke) Comparison is made with the DAS value in (Part). This can be achieved by providing a feeder in the periphery of the rim portion even in the center gate bill, and by providing a feeder in the vicinity of the hub portion in the side gate.
[0012]
As a casting mold for a light alloy wheel for a vehicle suitable for the present invention, a center gate is provided at the center of a mold cavity forming a disk portion, a side gate is provided in a mold cavity forming a rim portion, and the rim portion It is preferable to provide a mold cooling structure in which the mold cooling strength at the hub portion can be made larger than the mold cooling strength at. The strength of mold cooling can be determined by measuring the surface temperature of the lower mold and the horizontal mold by thermography after casting the cast product.
[0013]
The DAS value indicates the strength of the cast aluminum material, and the smaller the DAS value, the higher the strength. The DAS value of the spoke part as in the present invention can be reduced by a casting mold for a light alloy wheel for a vehicle having a disk part and a rim part including a hub part and a design part. This was achieved by using a casting mold characterized by providing cooling means in the bolt hole forming convex portion. Further, this cooling means is a cooling pipe in which a cooling part that becomes a cavity toward the convex direction of the bolt hole forming convex part is formed, and a jet outlet for spraying mist on the vicinity of the convex part of the cooling part is provided. A structure in which is provided in the cooling unit is preferable. Further, as another structure, a structure having a double pipe structure composed of an outer cylinder and an inner cylinder, which are built in the convex direction of the bolt hole forming convex portion, is preferable. Details will be described in Examples.
[0014]
The mold for forming the bolt hole concave portion is the bolt hole forming convex portion 81 in FIGS. 1 and 2, but this portion is close to the position where the molten metal first enters the cavity by the center gate method, etc. Become. Further, unlike a substantially cylindrical rim portion, it has a relatively complicated shape having bolt holes and the like. When viewed from the molten metal to be cast, it is a wall shape in the vertical direction, and this wall surface tends to cause melting of the mold, seizure of the molten metal, and the like. Therefore, it is very preferable to use a mold having a structure in which a cooling pipe is provided along the bolt hole recess so as to strongly cool the vicinity of the bolt hole. In addition, the releasability is improved, and a concave portion for a bolt hole having a taper portion inclination of 5.0 ° or less, and further 3.0 ° or less can be formed.
[0015]
In order to obtain a bolt hole shape with a small inclination of the taper portion, strict drive control of the mold is necessary when the solidified wheel is taken out of the mold. When opening the lower mold or the upper mold forming the disk portion, it is preferable to move the movable platen by using a parallel control drive device that pushes up the movable platen at three or more locations synchronously. A synchronous piston is provided on the upper platen, the upper plate is pushed up, and the upper plate at the lowermost position is moved in parallel to a height of about 20 to 30 mm. Alternatively, three or more synchronous hydraulic cylinders may be provided on the lower platen to directly push up the movable platen. If the number is less than two, the movable platen tends to tilt, making it difficult to make a product with a small taper tilt.
[0016]
In a conventional wheel casting machine, the movable platen is simply lifted by a single hydraulic cylinder and the mold is simply opened. However, wheel casting has a structure in which a holding furnace is provided in the vicinity of the lower mold platen. In such a configuration, the lower mold platen is likely to thermally expand. Since the dimensional difference due to thermal expansion differs between the upper mold platen and the lower mold platen, it is necessary to leave a gap of about 0.3 to 0.5 mm between the inner diameter of the guide and the outer diameter of the guide post. However, this gap causes the phenomenon that the movable platen constantly rises while tilting somewhere. If the inclined part of the spoke part or the hub part has a tapered part inclination of 6.0 to 8.0 °, the inclination of the movable platen is an acceptable range that does not cause a problem, and the shape of the molded product is impaired. The product could be released without any problem. However, when the inclination of the taper portion is 5 ° or less, galling is likely to occur in the concave portion of the spoke portion or the hub portion. When released from the lower mold, the product has a temperature of 400 to 450 ° C. and has low strength. In particular, when the design surface has a complicated shape, it is easy to be taken by the lower mold and the strength is weak with respect to the pulling direction. Therefore, detailed consideration of the movable platen equipped with the upper mold at the time of mold release is a very important technology. The distance that the upper mold must rise parallel to the lower mold is about 5 to 20 mm at the maximum from the clamping position. If it rises more than that, even if the movable platen tilts somewhat, the design surface and the lower mold will not collide. In order to lift the movable platen by strict control up to this level, it is necessary to perform parallel movement control in which the upper mold or the movable platen fixed to the upper mold is simultaneously pushed up by the same amount of movement. A four-synchronous vertical cylinder system is particularly effective. The cylinder may be driven using a current control valve or a servo valve.
[0017]
Further, the upper casting mold is generally pushing the lower mold with a clamping force of 200 kN. Since the hydraulic pressure is about 10 MPa, when this 10 MPa is dropped to substantially 0 MPa at a speed of less than 0.01 seconds, the deformation due to the stress applied to the casting machine is released at once, and surge pressure is generated in the hydraulic circuit. As a result, the entire casting machine vibrates and the movable platen does not move parallel to the lower mold, or the upper mold moves laterally with respect to the lower mold, and the lower mold and the design surface are easily galled. The time until the actual valve is fully opened is about 0.02 seconds, but the mold clamping force becomes 0 MPa in about half of the time. Therefore, the mold clamping force is removed for a long time of 0.05 seconds or more, more preferably 0.10 seconds or more, and the impact of the casting machine due to sudden oil pressure reduction is reduced, resulting in a design without galling. The surface can be molded.
[0018]
Further, it is preferable to increase the clamping force so that unnecessary vibration and stress are not applied during clamping. If the mold is abruptly clamped, the entire casting will be vibrated. The total weight of the movable platen and the lower die is about 3 to 4 tons, and stress strain of about 1 mm is generated in the vertical direction on the upper platen and the lower platen. In addition, since the parallel direction is also affected at the time of mold clamping, it is preferable to perform mold clamping at a predetermined speed in order to produce an aluminum wheel with a small taper portion inclination.
[0019]
When casting using the side gate at the rim part, the pouring gate position is preferably at least above the design part surface, and more preferably higher than the design part back surface. In this way, it is possible to reduce the occurrence of the hot water boundary surface of the molten metal poured from the center gate and the side gate in terms of design. Further, by providing a high side gate, it is possible to reduce the occurrence of defects due to the hot metal effect due to the weight of the molten metal remaining in the rim even if the vicinity of the center gate is solidified early.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
(Example 1)
Hereinafter, the details of the present invention will be described with reference to the drawings.
FIG. 7 is an example of casting a light alloy wheel for a vehicle according to the present invention, and is a diagram showing an outline of equipment when an aluminum alloy wheel is cast by low pressure casting. A holding furnace 2 is provided in the sealed container 1, and a lower platen 3 is attached on the sealed container 1 to seal the sealed container 1. The lower mold platen 3 is provided with a stalk 4 for replenishing a molten aluminum alloy 5 to the mold at the center, and the lower end of each stalk is immersed in the molten metal 5 in the holding furnace 2. The upper end of the stalk is connected to the gate 7 of the mold through the gate bush 6 fitted in the lower mold platen 3 and the lower mold 8 of the mold. The molten metal poured through the stalk 4 flows into the lower mold 8 and is poured into a cavity that forms the hub portion of the wheel.
[0021]
The lower mold 8 of the mold is attached to the lower mold platen 3. The lower mold 8 is a fixed mold and is a surface that forms a design portion in the wheel. In the present embodiment, the minimum taper portion inclination was 3.5 °, and the minimum cross-sectional area of the spoke portion was 100 to 250 mm ² . Further, the thickness in the axial direction was 25 mm or more, the minimum width was 4.0 to 10.0 mm, and the taper portion inclination was 3.5 ° at a portion of 50% or more of the taper portion inclination of the spoke portion. Both sides are laterally movable molds 10 and form the outer peripheral surface of the wheel rim. The upper mold 12 of the mold is attached to the movable platen 14. The upper mold 12 is a so-called movable mold, and forms the back surface of the design portion for attaching the wheel to the car and the inner peripheral surface of the 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 a 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. 7, the position where the upper plate 17 has reached the lowest end is indicated by a broken line. This lowermost position is the position when the upper mold 12 is clamped with the horizontal mold 10 and the lower mold 8.
[0022]
A detailed form of the lower mold 8 is shown in FIG. As shown in FIG. 2, the lower mold 8 has cooling water cooling mechanisms 50 and 51 disposed therein. The water cooling mechanism 51 is disposed with its end facing the bolt hole forming convex portion 81 which is a bolt hole concave portion formed on the disk surface of the wheel so as to mainly cool the vicinity of the hub portion. The taper portion inclination of the bolt hole forming convex portion 81 is 3.0 to 5.0 °. Cooling water is poured into the outer tube 50a of the water cooling mechanism 50 toward the bolt hole forming convex portion 81 through the inner tube 50b. The cooling unit has a double-pipe structure, and is configured such that the flow direction of water in the inner pipe and the flow of water between the outer pipe 50a and the inner pipe 50b are opposite to each other. The cooling water that has reached the tip of the bolt hole forming convex portion 81 from the inner pipe flows through the outer pipe 50b and returns. Two cooling pipes 50c are provided in the cooling unit, and the cooling water is controlled to pass through the inside at a predetermined casting timing. A cooling mechanism 51 for cooling the disk portion (particularly the spoke portion) has a groove 51a formed in the lower portion of the lower die so as to be substantially circular around the wheel axis in the vicinity of the lower portion of the spoke portion die 82. The groove 51a is sealed by a sealing member 51b to form a cooling water passage. Water is supplied from the cooling pipe 51c to the cooling water passage to cool the vicinity of the spoke part mold 82. When the taper portion inclination of the bolt hole forming convex portion 3 is 3 to 5 °, if the mold surface temperature at the bolt hole forming convex portion is 450 ° or more, the coating mold is peeled off and the molten metal reacts. Since seizure occurs, the cooling conditions are set so that the maximum temperature is lower than that temperature.
[0023]
The casting operation is performed according to the following procedure. After closing the lower mold 8, 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 put into the sealed container 1 from the pressurized gas inlet pipe 18. Send it in. The molten metal 5 held at about 700 ° C. in the holding furnace 2 is pushed up through the stalk 4b by the fed pressurized gas, and the mold temperature is maintained at 350 to 450 ° C. enter. The cavity part of the mold is coated with a coating that combines heat retention and mold release. After about 2 to 3 minutes, the pressurization is evacuated, the molten metal 5 in the unsolidified stalk 4 is returned to the holding furnace 2, and the molten metal in the mold is awaited to solidify. When solidification of the molten metal in the mold is completed and the take-out temperature reaches about 400 to 450 ° C., the mold is opened, and the upper mold is raised with the cast product (wheel) attached to the upper mold. The wheel is separated from the upper mold by the push pin fixed to the upper mold platen when it rises to some extent, and the wheel is taken out using the detachable arm 11. This cycle is repeated to cast the product.
[0024]
The descending hydraulic pressure was reduced from 10 MPa to 0 MPa over 0.20 seconds, and the upper mold was raised relative to the lower mold. The oil pressure gradually decreased over 0.20 seconds and did not give a large vibration to the casting machine. Furthermore, it was confirmed that the movable platen was not tilted from beginning to end, but moved upward while maintaining parallelism with respect to the upper platen. In addition, 20 vehicle light alloy wheels of 5 ° or less were manufactured at 50% or more of the inclination of the spoke taper portion, and the design surface was observed for galling or deformation. Generation | occurrence | production of the galling of the design surface was not confirmed, but the wheel which has a favorable shape was obtained. Table 1 shows DAS values obtained by measuring the portions (1) to (3) shown in FIG. Moreover, the structure | tissue observation photograph of a bolt hole vicinity is shown in FIG. It was confirmed that the DAS value near the bolt hole was very small and smaller than the intersection. The DAS values in the table were measured at the side gate position cross section, but the same tendency was observed for the DAS values on the 90 ° side. Similar effects were obtained even when the side gate method or the multi-gate method was used.
[0025]
[Table 1]

[0026]
(Comparative Example 1)
The cooling water was poured only into the water cooling mechanism 51 shown in FIG. 2, and casting was performed without flowing the cooling water into the water cooling mechanism 50. When casting was performed for about 200 to 300 cycles, the molten metal was seized around the bolt hole forming convex portion 81 shown in FIG. 2, resulting in defective molding of the product. In addition, it was necessary to spend time on the maintenance of the mold. The measured value of the DAS value is also shown in Table 1. In particular, the DAS value near the bolt hole is different from that of the present invention. A tissue observation photograph is shown in FIG.
[0027]
(Example 2)
Moreover, the detailed form of another lower mold | type is shown in FIG. 1 and 2 are denoted by the same reference numerals. As shown in FIG. 1, the lower mold 8 has cooling water cooling mechanisms 52 and 51 arranged therein. In the water cooling mechanism 52, a hollow portion 52a extending in a convex direction is disposed in a bolt hole forming convex portion 81 which is a concave portion for a bolt hole formed on the disk surface of the wheel so as to mainly cool the vicinity of the hub portion. Yes. The cooling pipe 52b was inserted deeply into the cavity 52a, and mist was supplied from the external cooling pipe 52c to cool the inside of the cavity. The discharged mist cools the vicinity of the convex portion, returns through the space between the cooling pipe 52b and the hollow portion 52a, and is discharged from the communicating portion 83 to the outside of the lower mold.
[0028]
【The invention's effect】
As described above, according to the present invention, the optimal cooling structure is housed in the lower concave portion for forming the bolt hole, so that a wheel having much higher strength and higher safety than the conventional one can be provided. In addition, it is possible to form a bolt hole recess with a small taper inclination even in a method of pouring molten metal from the hub portion due to improved releasability.
Further, by using the mold of the present invention, galling at the time of releasing the wheel is eliminated, and the working efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a cooling mechanism of a lower mold.
FIG. 2 is a cross-sectional view showing another lower mold cooling mechanism.
FIG. 3 is a cross-sectional view of a main part around a bolt hole.
FIG. 4 is a diagram showing a cross-sectional shape of a wheel.
FIG. 5 is a photograph of the metal structure near the bolt hole of the present invention.
FIG. 6 is a photograph of a metal structure in the vicinity of a bolt hole in a conventional center gate bill.
FIG. 7 is an example of a casting machine used in the present invention.
[Explanation of symbols]
1: closed container, 2: holding furnace, 3: lower mold platen, 4: stalk, 5: molten metal, 6: gate gate, 7: gate part, 8: lower mold, 9: guide pin, 10: horizontal mold, 11: Desorption arm, 12: upper mold, 13: upper mold platen, 14: movable platen, 15: guide post, 16: guide, 17: upper plate, 18: pressurized gas insertion tube, 20: four synchronous pistons, 21: Hydraulic cylinder, 30: Aluminum wheel, 31: Hub part, 32: Design part, 33: Rim part, 34: Spoke part, 35: Design hole, 36: Recess for bolt hole, 37: Bolt hole, 38: Hub hole, 39 bolt contact part, 40: taper part inclination, 41: design surface side, 42: ceiling thickness, 43: cast-out part slope, 44: cast-out part, 50, 51: cooling mechanism, 81: for bolt hole formation Convex part, 82 spoke part mold

Claims (4)

  A light alloy wheel for a vehicle having a disk part and a rim part including a hub part and a design part, and a DAS value near a bolt hole provided in the hub part from a DAS value at an intersection of the rim part and the disk part. A light alloy wheel for vehicles characterized in that is smaller. A light alloy wheel for a vehicle having a disk part and a rim part including a hub part and a design part, and a DAS value near a bolt hole provided in the hub part from a DAS value at an intersection of the rim part and the disk part. A light alloy wheel for a vehicle , wherein the DAS value in the vicinity of a bolt hole provided in the hub portion is smaller than 30 μm.   The light alloy wheel for a vehicle according to claim 1 or 2, wherein the light alloy wheel for a vehicle is manufactured by a casting method in which a molten metal is poured from at least a mold cavity of a hub portion during casting. A bolt hole recess is provided around the bolt hole of the hub portion on the disk surface of the vehicle light alloy wheel, and the taper portion inclination of the bolt hole recess is 5.0 ° or less. 4. The light alloy wheel for vehicles according to any one of 3 above.

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