JPH04274858A - Casting method for wheel for vehicle - Google Patents

Abstract

PURPOSE:To enhance the strength of a rim part by quickening solidification, and also, to improve the productivity by shortening a casting cycle time. CONSTITUTION:A segmental die 3 for forming a cavity 5 for forming a rim part of a wheel by surrounding the lower die 1 and the upper die 2 is opened in an early stage at the time point when a surface layer part of a molten metal in the cavity 5 is solidified. When it remains closed, heat radiation to the segmental die 3 from the molten metal is suppressed and solidification is delayed by a clearance formed between the cavity and the segmental die 3 by solidification and contraction of the molten metal, but by opening in an early stage, the rim part is cooled by the open air, and solidification is quickened.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for casting vehicle wheels such as aluminum wheels.

0002

[Prior Art] Conventionally, as seen in Japanese Unexamined Patent Application Publication No. 2-151344, a lower mold and an upper mold forming a cavity for molding a disk portion of a wheel, and a rim portion of a wheel are molded by surrounding both molds. It is known to cast vehicle wheels using a mold consisting of a split mold that forms a cavity.In this case, when the molten metal in the cavity has completely solidified, the split mold is opened and the lower mold and the lower mold are opened. The upper mold is opened to take out the product.

0003

[Problem to be Solved by the Invention] By the way, when the molten metal in the cavity for the rim part solidifies, a gap is created between the mold and the split mold due to the shrinkage caused by the solidification, and this gap acts as a heat insulating layer to separate the mold from the rim part. Heat dissipation to the mold is inhibited, solidification of the rim portion is delayed, cycle time becomes longer, and cavities are more likely to form in the rim portion. An object of the present invention is to provide a casting method that can eliminate the above-mentioned problems caused by delayed solidification of the rim portion.

0004

[Means for solving the problem] In order to achieve the above purpose,
The present invention uses a mold consisting of a lower mold and an upper mold that form a cavity for molding the disc part of the wheel, and a split mold that surrounds both molds and forms a cavity for molding the rim part of the wheel. In the method of casting vehicle wheels, when the surface layer of the molten metal in the rim cavity has solidified, the split mold is opened to cool the rim with outside air, and then the lower and upper molds are opened. I made it.

[0005]

[Operation] By opening the split mold, the rim portion is exposed to the outside air and cooled, promoting solidification of the rim portion. In this case, it is desirable to determine the degree of solidification of the molten metal in the rim cavity by detecting the temperature of the split mold, and to open the split mold when the temperature of the split mold falls to a predetermined temperature.

[0006]

[Embodiment] Fig. 1 shows a mold for casting a vehicle wheel, and the mold includes a lower mold 1, an upper mold 2 that can be raised and lowered, both molds 1,
It is composed of a plurality of horizontally slidable split molds 3 surrounding the upper mold 2, and the upper mold 2 and the lower mold 1 are separated by clamping by lowering the upper mold 2.
Cavity 4 where the disc part of the wheel is formed between
Then, the upper and lower molds 1 are clamped by sliding the split mold 3 inward.
, 2 and the split mold 3, a cavity 5 for molding the rim portion of the wheel is formed. For split type 3,
A sprue 6 is formed which communicates with the cavity 5 for the rim part, and the molten aluminum in the molten metal holding furnace 7 provided below the lower mold 1 is connected to the hot water supply pipe 8 by air pressure applied to the holding furnace 7. The molten metal was supplied to a sprue 6 through a runner 9 formed in the mold 1, and the molten metal was injected into the cavities 4 and 5 from the sprue 6. The lower mold 1 has a cooling metal 10 in which a water cooling pipe 10a is cast.
, and the upper mold 2 has a cooling metal 11 in which an air cooling pipe 11a is cast.
Further, a riser part 12 is formed in the center of the upper mold 2, and the molten metal in the cavity 4 for the disc part is solidified from the lower mold 1 side, which is the outer surface, and is poured onto the outer surface of the disc part. It is possible to cast a wheel disk without unevenness due to sink marks or the like. In the figure, reference numeral 13 denotes a protrusion for forming an opening protruding from the lower die 1 in order to form an opening such as an air hole around the disk portion.

The wheel casting process is as shown in FIG.
A process A of clamping the split mold 3 and the upper mold 1, a process B of applying air pressure to the holding furnace 7 and injecting the molten metal into the cavities 4 and 5, and holding the molten metal in the cavities under pressure using air pressure. step C, cooling step D after releasing the pressure, and mold opening step E.
Usually, the split mold 3 and the upper mold 1 are opened after the cooling process D, but in this embodiment, the split mold 3 is opened after the air pressure is exhausted in the cooling process D. ,
The upper mold 2 was opened after the cooling process. Split type 3
If the cooling process was performed with the mold clamped, the solidification and shrinkage of the molten metal in the rim cavity 5 would create a gap between the molten metal and the split mold 3, which would inhibit heat radiation to the split mold 3. While the solidification of the molten metal is delayed, when the split mold 3 is opened, the rim portion is exposed to the outside air and cooled, promoting solidification. The time from the start of pouring to the completion of the pressurizing process was set to 170 seconds, and then the split mold 3 was opened with a waiting time of 20 seconds required for exhausting the air pressure, and the rim part was broken 50 seconds after the pressurizing process. The temperature of the rim decreased to 384°C, but when the split mold 3 remained clamped, the temperature of the rim remained 393°C even 60 seconds after the pressurizing process. In addition, when forming the sprue 6 in the split mold 3, the runner 9 of the lower mold 1 is opened to the atmosphere by opening the split mold 3, and if the split mold 3 is opened early as described above, the runner 9 of the runner 9 is opened to the atmosphere. The molten metal remaining below is surely dropped by the air that enters through the gap in the runner 9. Therefore, the lower end of the runner scrap part that is solidified and formed in the runner 9 swells due to the solidification of the remaining molten metal that adheres to it and gets caught in the runner 9 when the product is released from the mold, causing the sprue part to rupture and form the product. Does not cause problems such as damage.

[0008] By the way, the surface layer of the molten metal in the cavity 5 for the rim part solidifies in the pressurizing process C, and the split mold 3
The mold does not lose its shape even when the mold is opened, but in order to reliably prevent the mold from deforming, as shown in Figure 3, a temperature sensor 14 such as a thermocouple to detect the temperature of the split mold 3 is built into the split mold 3 to ensure that the mold temperature is at a predetermined level. It is sufficient to open the split mold 3 when the temperature drops below the temperature. In this embodiment, in order to detect the temperature of the upper part, the middle part, and the temperature of the sprue 6 of the cavity 5, the temperature sensors 14 are provided in three stages, upper and lower, so that the temperatures of the upper part, the middle part, and the sprue are determined respectively. The divided mold 3 was opened when the temperature was below 420°C, 430°C, and 440°C.

[0009]

[Effects of the Invention] As is clear from the above description, according to the invention of claim 1, early opening of the split mold allows the rim portion of the wheel to be cooled with outside air to promote solidification, thereby increasing the strength of the rim portion. In addition, according to the invention of claim 2, the degree of solidification of the molten metal can be determined from the temperature of the split mold, and the timing of opening the split mold can be appropriately controlled. have an effect.

[Brief explanation of the drawing]

[Figure 1] Longitudinal cross-sectional view of a mold used to carry out the method of the present invention

[Figure 2] Time chart showing an example of the casting process according to the method of the present invention

[Figure 3] Longitudinal cross-sectional view of the main parts showing a modified example of the mold

[Explanation of symbols]

1 Lower mold
2 upper mold, 3 split mold
4 Cavity for disc part

Claims (2)

[Claims] Claim 1: Using a mold consisting of a lower mold and an upper mold that form a cavity for molding a disc portion of a wheel, and a split mold that surrounds both molds and forms a cavity for molding a rim portion of a wheel. In this method, when the surface layer of the molten metal in the rim cavity has solidified, the split mold is opened to cool the rim with outside air, and then the lower and upper molds are opened. A method for casting a vehicle wheel, characterized by: 2. The method for casting a vehicle wheel according to claim 1, wherein the temperature of the split mold is detected to determine when to open the split mold.