JPS61283452A - Forcibly cooling type casting method - Google Patents

Abstract

PURPOSE:To accelerate directional solidification and to efficiently obtain a casting having high quality by retreating a sliding pin and spraying a cooling medium while the part near the top end of the sliding pin forming part of a product cavity is in the half-solidified sate. CONSTITUTION:An ejector plate 5 is raised to position the top end of the sliding pin 3 to the product cavity surface. A molten metal is poured into the cavity. The pin 3 is retreated to eventually communicate the closed cooling medium supply hole 7 and cooling medium discharge hole 8 with a sliding pin hole 6 at about the time when the binary eutectic reaction to considerably decrease fluidity starts on progression of the solidification of the molten metal 12 in contact with the cavity surface of a drag 2. Water 13 is successively supplied from a cooling medium supply source, then the water 13 arrives at a cooling medium supply pipe 9 and is blown from nozzles 10 toward the hole 7 to directly cool the casting 14 and thereafter the water is discharged through the hole 8. The spraying of the water is stopped after the entire part of the casting 14 solidifies. The plate 5 is raised and the casting 14 is pushed to the outside of the mold by the pin 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a forced cooling casting method, in particular a forced cooling method that promotes directional solidification by partially forcing molten metal to efficiently produce high quality castings. This invention relates to a cooling casting method.

[Conventional technology]

In order to produce reliable aluminum alloy castings without casting defects, etc., it is desirable that the molten metal solidify rapidly and that the molten metal solidify directionally. Conventionally, mainly in gravity casting methods and low-pressure casting methods, solidification of molten metal has been promoted by cooling the mold with water or air. However, such cooling method
However, as shown in Table 1, 5KD61, a commonly used mold material, has a much lower thermal conductivity than aluminum, and is difficult to apply to the product cavity surface. Cooling efficiency was not sufficient due to the coating mold, etc.

Table 1: Thermal conductivity of various materials In this case, it is necessary to adjust the mold temperature relatively strictly to prevent poor water flow during pouring due to overcooling of the mold. Since the temperature varies periodically with the casting cycle, relatively sophisticated control technology is required to control the temperature of the mold. Furthermore, since a cooling means is incorporated into the mold, the mold structure becomes complicated and the cost of the mold increases.

In addition, in order to eliminate casting defects, the installation location, shape, capacity, etc. of the feeder are selected and set empirically in order to perform directional solidification. However, due to the shape constraints of the casting, there are limits to the selection and setting of the installation location, shape, capacity, etc. of the feeder, and it is often impossible to achieve good directional solidification using the feeder alone.

Therefore, the present applicant proposed a direct cooling casting method for castings, which promotes directional solidification by providing an extra wall part in the casting during casting and forcibly cooling this extra wall part (Japanese Unexamined Patent Publication No. 57-109
Publication No. 559). This direct cooling casting method has the advantageous effects of promoting directional solidification, improving the quality of the casting, and shortening the casting cycle.

The applicant has also proposed a forced cooling casting method in which an iron pipe is inserted into a casting, and the casting is forcibly cooled by passing water through the iron pipe. Similar to the direct cooling casting method, this forced cooling casting method promoted directional solidification, improved the quality of the casting, and shortened the casting cycle.

[Problem that the invention seeks to solve]

However, in the above-mentioned casting direct cooling casting method, there are problems in that the yield of the casting is poor because an extra wall part is provided in the casting for forced cooling, and it takes time to remove the extra wall part after casting. .

Further, in the above-mentioned forced cooling casting method, it is necessary to insert the iron pipe into the product cavity, but depending on the shape of the casting, it may be impossible to insert the iron pipe and it may not be applicable.

Therefore, it has been desired to develop a forced cooling casting method that can improve casting quality by ensuring directional solidification, shorten casting cycle time, and can be applied to a high yield regardless of the shape of the casting.

[Means for solving problems]

The above problem is solved by the forced cooling casting method of the present invention, which will be described below.

That is, the forced cooling casting method of the present invention is a forced cooling casting method that performs directional solidification by pouring molten metal into a product cavity defined by a mold and forcibly cooling the molten metal during the solidification process. Then, after the vicinity of the tip of the sliding pin that forms a part of the product cavity is semi-solidified and loses fluidity, the sliding pin is retreated and a cooling medium is poured into the sliding pin hole in which a space is formed. It is characterized by directly cooling the casting by spraying it with.

In the present invention, a sliding pin hole is used as a place to cool the casting. These sliding pin holes and sliding pins can be provided at any location that requires cooling, if necessary. Note that a typical mold is provided with an extrusion pin for ejecting the casting after solidification of the molten metal. This extrusion pin forms a product cavity together with the mold. Therefore,
An extrusion pin may be used as the sliding pin. After pouring, if the molten metal near the tip of the sliding pin becomes semi-solid and loses its fluidity, there will be no problem even if the sliding pin is moved back.

After the sliding pin retreats, a cooling medium is sprayed into the sliding pin hole in which the sliding pin-shaped space is formed.

At this time, the cooling medium may be sprayed directly toward the casting from below the sliding pin hole, or a supply hole and a discharge hole for supplying and discharging the cooling medium toward the sliding pin hole may be provided separately. The cooling medium may be supplied to the sliding pin 6 through the hole and discharged through the discharge hole.

At this time, a liquid such as water, a gas such as compressed air or nitrogen, or a mixture thereof can be used as the cooling medium.

Note that the detection of the semi-solid state near the sliding pin may be controlled by providing a thermocouple or the like in the mold near the sliding pin to directly measure the temperature, or it may be possible to control the detection of the semi-solid state in the vicinity of the sliding pin by directly measuring the temperature. The time required for the vicinity of the sliding pin to become semi-solidified may be measured, and the sliding pin may be moved back after a predetermined period of time has elapsed from the start of pouring.

[Effect]

According to the forced cooling casting method of the present invention, it has become possible to directly cool the casting using the sliding pin hole. That is,
After clamping the mold, when molten metal is poured into the product cavity from the spout, the molten metal begins to solidify from the parts that are in contact with the mold and the thinner parts. Therefore, the vicinity of the tip of the sliding pin facing the product cavity begins to solidify relatively early. When the vicinity of the tip of the sliding pin becomes semi-solidified, the sliding pin is moved back to make the sliding pin hole hollow. Then, a cooling medium such as water or compressed gas is sprayed into the sliding pin hole. Then, since the cooling medium directly cools the casting and the mold forming the sliding pin hole, the molten metal is cooled mainly in the part of the casting where the tip of the sliding pin is in contact, and directional solidification occurs. promoted.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

(First Example) Here, FIG. 1 is a sectional view showing an outline of each step of a forced cooling casting method according to a first example of the present invention.

In FIG. 1, 1 is a horizontal mold made of a self-hardening material, and 2 is a lower mold made of 5KD61.

A sliding pin 3 which also serves as an extrusion pin is slidably provided on the lower mold 2, and a product cavity 4 is defined by the horizontal mold 1, the lower mold 2, and the sliding pin 3.

The sliding pin 3 has one end connected to the extrusion plate front plate 5a and the extrusion plate rear plate 5b.
The other end is inserted into a sliding pin hole 6 formed in the lower mold 2 so that it can freely slide.

This extrusion plate 5 is connected to a cylinder (not shown),
By driving this cylinder, the extrusion plate 5 and the sliding pin 3 are moved forward and backward relative to the sliding pin hole 6.

A plurality of coolant supply holes 7 and coolant discharge holes 8 are formed in the lower mold 2 diagonally downward with respect to the sliding pin hole 6 . A cooling medium supply pipe 9 is disposed between the lower mold 2 and the extrusion plate 5 so as to surround the sliding pin 3. This cooling medium supply pipe 9 is provided with a first nozzle 10 at a position facing the cooling medium supply hole 7 and on the same straight line as the cooling medium supply hole 7, and can cool the lower surface of the lower mold 2. A second nozzle 11 is provided facing upward. Note that the cooling medium supply pipe 9 is connected to a cooling medium supply source (not shown).

Next, the ζ operation will be explained.

First, a cylinder (not shown) is operated to raise the extrusion plate 5, and the tip of the sliding pin 3 is positioned on the product cavity surface. As a result, the product cavity 4 is defined, and
Both the cooling medium supply hole 7 and the cooling medium discharge hole 8 are connected to the sliding pin 3.
Closed by

At this time, water has not yet been passed through the cooling medium supply pipe 9. This state is shown in FIG. 1 (al).

Fig. 1 (Al) In the state shown in FIG.
When the solidification of the molten metal 12 progresses and a binary eutectic reaction begins, in which the fluidity of the molten metal 12 is greatly reduced, a cylinder (not shown) is operated to lower the extrusion plate 5, and the sliding pin 3 is moved to the position shown in FIG.
Retract it to the position shown. As a result, the coolant supply hole 7 and the coolant discharge hole 8, which had been closed, communicate with the sliding pin hole 6. Subsequently, water 13 as a cooling medium is supplied from a cooling medium supply source (not shown). Then, this water 13 reaches the coolant supply pipe 9 and is sprayed toward the coolant supply hole 7 from the first nozzle IO.

At this time, the direction of the first nozzle 10 and the cooling medium supply hole 7
are on the same straight line, most of the water 13 enters the sliding pin hole 6 through the cooling medium supply hole 7, directly cools the casting 14, and then passes through the cooling medium discharge hole 8 to the outside of the system. is discharged to. Also, at the same time as this cooling, the second nozzle 11
Water is also sprayed toward the lower mold 2 from above. FIG. 1(b) shows the state at this time.

After the entire casting 14 has solidified, the water spraying is stopped,
As shown in FIG. 1(C), a cylinder (not shown) is operated to raise the extrusion plate 5, and the sliding pin 3 moves the casting 14.
Push it out of the mold.

When the resulting casting was examined, it was confirmed that directional solidification was occurring from the lower mold toward the E direction. Further, in this example, a high quality aluminum alloy casting without casting defects such as cavities was obtained.

Further, in this embodiment, unlike in the conventional direct cooling type casting method, the casting is not provided with an extra wall portion, so that the yield of the product is improved.

Further, since no excess thickness is provided, there is no need to remove the excess thickness in a post-processing process, and the casting cycle can be shortened.

Furthermore, unlike conventional forced cooling casting, there is no need to provide a cooling pipe that penetrates the casting, so it can be applied to all castings regardless of the shape of the casting.

(Second Example) As a second example, the cooling effect of the forced cooling casting method of the present invention was tested.

Here, FIG. 2 is a sectional view showing each step of the forced cooling casting method according to the second embodiment of the present invention, and FIG.
It is a graph showing the cooling effect of an example and a conventional example.

In Figure 2 (al), ■ is a horizontal type made of sand mold,
2 is a lower mold made of 5KD61. This lower die 2 is provided with a sliding pin hole 6, into which the sliding pin 3 is slidably inserted. And horizontal type 1
A thermocouple 15 for measuring the temperature of the central part of the casting is attached approximately to the center of the product cavity 4 defined by the lower die 2 and the sliding pin 3. A molten aluminum alloy (JIS AC4CH) 12 is poured into this mold. FIG. 2(a) shows the state immediately after pouring. Note that the temperature of the lower mold 2 before pouring is set at 100 to 150°C.

Approximately one minute after pouring, the lower part of the molten metal 12, that is, the portion that is in contact with the lower die 2 and the sliding pin 3, starts a binary eutectic reaction. At this time, as shown in FIG. 2 (bl), the sliding pin 3 is moved back, the cooling pipe 16 is positioned below the sliding pin hole 6, and the cooling pipe 16 is directed toward the sliding pin hole 6, that is, the casting. A cooling medium 17 was sprayed thereon.At this time, compressed air and a mixed vapor of compressed air and water were used as the cooling medium.

As a result, measurement results as shown in FIG. 3 were obtained using a thermocouple. In FIG. 3, A shows the case where a mixed vapor of compressed air and water is used as the cooling medium in this embodiment, and the opening shows the case where only compressed air is used as the cooling medium. For reference, a conventional method in which the lower part of the lower mold 2 is cooled with compressed air in the state shown in FIG. 2 (al) is also shown.

From FIG. 3, it can be seen that according to this embodiment, the time required to complete the binary eutectic reaction is shortened to 1/2 to 1/3 of that of the conventional method. In addition,
If only water is used, the coagulation time can be further shortened.

In addition, since the binary eutectic reaction time is shortened, aluminum alloys containing silicon as a component, such as JIs AC4
When using C, AC4CH, AC2B, etc., eutectic Si
The toughness of the casting improves because it becomes finely granulated.

Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and includes various embodiments within the scope of the claims. .

〔Effect of the invention〕

As described above, the forced cooling casting method of the present invention provides the following effects.

(a) Unlike the conventional direct cooling casting method, there is no need to provide extra wall for forced cooling in the casting, so the yield of the product (casting) is greatly improved.

(b) Unlike the conventional direct cooling casting method, there is no need to remove the excess thickness of the casting in the post-processing process, and cooling is performed immediately when the area near the sliding pin becomes semi-solidified. Therefore, the overall casting cycle can be shortened.

(c) Since directional solidification is promoted, casting defects such as cavities are suppressed, and high-quality castings can be obtained.

(d) Unlike the conventional forced cooling casting method, there is no need to install a cooling pipe inside the casting, so it can be applied to any shape of casting, and has great versatility.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing each step of the forced cooling casting method according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing each step of the forced cooling casting method according to the second embodiment of the present invention. FIG. 3 is a graph showing the cooling effect of the second embodiment of the present invention and the conventional example. l-・・−・−Horizontal type 2・−−−−Lower mold 3−・−・−・−Sliding bin 4−・・−・Product cavity 5・−・−Extrusion plate 6・−・・−Sliding Dynamic bottle hole 7 --- Coolant supply hole 8 --- Coolant discharge hole 9 --- Coolant supply pipe 10 --- First nozzle 11 --- --1・-Second nozzle l 2・---・・-? Boiled hot water 13-------・Water (cooling medium) 14----- Casting applicant Toyota Motor Corporation Fig. 1 fdl Fig. 2 tal Fig. 2 + b) Low-Kamako Ryo Harichi-J8 Hiroki 6th Confrontation M (Ge)

Claims (1)

[Claims] (1) A forced cooling casting method that performs directional solidification by pouring molten metal into a product cavity defined by a mold and forcibly cooling the molten metal during the solidification process, wherein a part of the product cavity After the area near the tip of the sliding pin that forms the mold is semi-solidified and loses its fluidity, the sliding pin is moved back and a cooling medium is sprayed into the sliding pin hole in which the space is formed to directly cool the casting. A forced cooling casting method characterized by: