JPS5881548A - Low pressure die casting method of wheel - Google Patents

Abstract

PURPOSE:To reduce casting cycles and to improve productivity in low pressure die casting for wheels by casting molten metal under pressure of the 1st stage, releasing side dies under pressure of the 2nd stage and cooling the outside surface of a rim forcibly. CONSTITUTION:When pressurized air is blown through an air introducing and discharging port 14a, pressure is exerted upon the surface of the molten metal in a crucible 8, and the molten metal enters dies through a down tube 9, whereby the wheel 1 is cast. Thereafter, the pressure of a holding furnace 13 is increased to open side dies 4a, 4b, and air is blown to cool a part of rim contour forcibly. On the other hand, molten metal is fed to a disc part while the pressurizing is held and the air in the furnace 13 is removed through the air introducing and discharging pipe 14. A top mold 2 is released, and the hub surfaces of the wheel hub 1 are qjickly cooled by the air through an air injection hole 20. The hub is clamped with a work removing device 19 and is removed from the bottom mold.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-pressure die casting method for wheels, which aims to shorten the casting cycle and improve productivity.

Traditionally, this type of wheel casting method includes gravity casting, low pressure casting,
There are die casting and molten metal forging methods.

The casting cycle for die casting and molten metal forging is said to be about 2 minutes, and although the productivity is better than gravity casting, low pressure casting, etc., there are still some problems in terms of quality (1) and yield (2). It is also considered disadvantageous compared to gravity casting or low pressure casting in terms of mold cost.

An example of the structure of a conventional low-pressure casting casting apparatus is shown in FIG. 1, and casting is performed using the cycle time shown in FIG. 2.

In Fig. 1, the mold of wheel (work) 1 is upper mold 2,
It consists of a lower mold 3 and horizontal molds 4a and 4b that open left and right, and are attached to a fixed platen 5 and a movable platen 6. The above-mentioned movable platen 6 is moved up and down by a pressure cylinder 7, and the horizontal type 4
a and 4b are configured to open left and right by horizontal movement cylinders 15a and 15b. The fixed platen 5 is provided with a nozzle 10 for injecting the molten metal in the molten metal pot 8 into the mold via the down tube 9. A heater 11 is provided around the outer periphery of the molten metal crucible 8 to heat the molten metal, and is installed in a holding furnace 13 together with a heat insulating material 12.

Further, the holding furnace 13 is provided with an air inlet/outlet port 14a, and when air at a predetermined pressure is sent through the air inlet/outlet pipe 14, the molten metal in the crucible 8 passes through the down tube 9 due to the surface pressure and exits the nozzle 10. Injected into the mold. In the conventional low-pressure casting method, as shown in FIG. 2, the air in the holding furnace is pressurized until it reaches point A of 0.51, and the molten metal in the crucible 8 is injected into the mold. In this state, the pressure is maintained at point 8, and at point B, the air in the holding furnace 13 is introduced into the air inlet and discharge pipe 1.
4, and held in the mold from point 0 to point 1 and cooled. During this time, one cycle is completed in about 8 minutes, and the sample is removed from the mold as shown in FIG. FIG. 3 is a diagram showing how to take out the wheel 1 from the mold.
When the lower mold is raised, the lower mold remains on the fixed platen 5, and the wheel 1 is attached to the upper mold and raised. When it rises above a certain distance, the ejector bin 16 attached to the upper die hits the ejector platen 17, so the tip of the bin 16 protrudes from the upper die 2, and the wheel 1 (workpiece) is removed from the upper die and moves to the lower part. The wheel receiver 18 is caused to fall onto the wheel receiver 18. The upper mold is provided with a drafting slope of 3° to 4° so that the wheel 1 adheres to the upper mold and rises, and at the same time is removed through the ejector bin 16.

As explained above, in the conventional low-pressure casting method, it takes about 8 minutes per cycle to take out the workpiece 1 from the mold, resulting in low productivity. Since the wheels are allowed to fall, the shock caused when they are removed from the upper mold and when they fall may cause distortion in the wheels.Therefore, a finishing allowance that takes into account the amount of distortion is required. This resulted in a high rate of defective products.

This invention has been made based on the above-mentioned circumstances, and is an improvement on the low-pressure casting method, which conventionally required about 7 to 8 minutes per cycle, by forced cooling, two-stage pressurization, and workpiece casting. The present invention provides a low-pressure die casting method for wheels that reduces the cycle time to 1/3, reduces machining allowance, lowers the defective rate, and improves productivity through improvements in ejecting.

Hereinafter, embodiments of the present invention will be described in detail based on FIGS. 4 to 7. FIG. 4 is a structural diagram of a casting apparatus used in the present invention. FIG. 5 is a graph showing one cycle of the method of the present invention and one cycle of the conventional method,
The solid line shows the method of this invention, and the dotted line shows the conventional method. 6 and 7 are detailed explanatory diagrams of this invention,
If the horizontal mold is removed in Figure 6, the upper mold is also removed in Figure 7.
- It is an explanatory diagram when using a device that cools the surface of the workpiece and increases the weight of the workpiece.

As shown by lines 0 to A in FIGS. 4 and 5, the crucible 8 is first filled with molten metal, and when pressurized air is blown from the air inlet/outlet 14a, pressure is applied to the surface of the molten metal in the crucible 8, causing the molten metal to melt. enters the mold from the down tube 9 through the nozzle 10, and the wheel 1 is cast. Approximately 0.5 YJ of point A
When the mold is filled with molten metal under the pressure of , it is held in this state at point E.

This point 1 is the same as the conventional method. Next, the pressure in the holding furnace 13 is increased by about 1 to 2 liters to create a riser effect.

At point F, as shown in FIG. 6, the horizontal molds 4a and 4b are opened and air is blown as shown by the dotted arrows to forcibly cool a portion of the rim contour. - The disk section is heated until 1,000 yen is maintained, and at point G, the air inside the holding furnace 13 is removed through the air introduction and discharge pipe 14, and the upper mold 2 is opened as shown in Fig. 7. At the same time, the workpiece is taken out at point H after the surface of the wheel 1 is rapidly cooled by air from the air injection hole 2° or while being forcedly cooled. Instead of the conventional method shown in Fig. 3, the workpiece is taken out using the workpiece take-out device 19 shown in Fig. 7, which gently grabs it from the lower die and takes it out, so no distortion occurs, and the machining allowance is approximately 1.51111mm compared to the conventional method.
~20 was required, but only about 0.5n is needed. Note that if the pressure is increased directly from point A to point F, the pressure will increase, so it is necessary to maintain A → E, and from point B to point F!
The two-stage pressure increase and the pressure retention from point F to point G are due to the riser effect. This is to prevent the formation of cavities due to the shrinkage of hot water during cooling. With the above method, the present invention allows workpiece removal at the flH point.

As explained in detail above, according to the low-pressure casting method for wheels according to the present invention, after casting at a predetermined first-stage pressure = 6-force and holding for a required time, the pressure in the holding furnace is reduced to a second-stage pressure.
When the pressure reaches the predetermined pressure, the horizontal mold is opened, and the pressure is maintained for the required time. After forced cooling of part of the FIJ mukonta, the upper mold is opened, and at the same time...
Since the workpiece is taken out after rapid cooling of the mold surface, the time for one cycle can be shortened to about 115 times compared to the conventional method.The workpiece is grabbed by the workpiece takeout device and taken out gently from the lower mold, so no distortion occurs. There is less machining allowance compared to conventional methods, and there are fewer defects and higher productivity. 1) Since forced cooling is performed using cold air, the structure becomes denser and the quality of the product can be improved. In addition, since there is no need to attach the wheel (workpiece) to the upper die and lift it as in the conventional method, the drafting slope can be set freely, and there are also effects such as being applicable to 2-impression.

[Brief explanation of drawings]

Fig. 1 is a structural diagram of a conventional casting device, Fig. 2 is a graph showing one cycle of the conventional low pressure casting method, Fig. 3 is an explanatory diagram of conventional workpiece removal, and Fig. 4 is a diagram of the casting device of the present invention. Structure diagram, Figure 5 is a graph showing one cycle of the method of this invention and one cycle of the conventional method, Figure 6 is a diagram showing the detailed explanation of this invention when the horizontal type is removed, and Figure 7 is the same diagram. , is an explanatory diagram when the horizontal mold and the upper mold are removed and the workpiece take-out device is used. 1...Wheel (work), 2...Upper die, 3...
Lower mold, 4a, 4b...Horizontal type, 13...Holding furnace, 19
...Workpiece take-out device. Patent applicant Topy Industries Co., Ltd. agent Patent attorney Hide Sato Akiaki 1 fake total 21q Total 51 - 9 Uga 4 Illustrations 5 Cabinets 1 Nine Kubi

Claims (1)

[Claims] In the wheel casting method, the wheel is cast at a predetermined first-stage pressure, held for a predetermined time, and then a second-stage pressure higher than the first stage is applied, and when the predetermined pressure is reached, the horizontal type is cast. After releasing the rim and holding it for a predetermined time while forcing the outer surface of the rim to cool, the upper mold is released at the same time as the pressure is released, and the workpiece is taken out after the rim surface is forcibly cooled or while it is being forcedly cooled. A low-pressure die casting method for wheels.