JP2010052000A - Internal chilling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal chilling method where, in the case the member to be internally chilled and a casting metal internally chilling the same are different kinds of materials, the member to be internally chilled is satisfactory and easily internally chilled. <P>SOLUTION: A wear resistant ring 1 is preheated and held into a casting mold 2, and, in a state where ultrasonic vibration is applied to the wear resistant ring 1 from a plurality of directions in such a manner that the whole of the wear resistant ring 1 is uniformly vibrated, an aluminum molten metal 20 is cast into the casting mold 2. Further, at least one selected from the frequency, amplitude and application time of the ultrasonic vibration is regulated in such a manner that the joined layer 1A of the wear resistant ring 1 and the aluminum molten metal 20 is made into a prescribed thickness. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cast-in method for casting a cast metal into a mold in a state where the cast-in member is held in a mold, and molding a cast product to which the cast-in member is joined.

  For example, since a piston of a diesel engine burns in a highly compressed state, adhesion and wear occur in a ring groove in which a piston ring is mounted. For this reason, in order to improve the adhesion resistance and wear resistance of the ring groove, when casting the piston, a ring having high adhesion resistance and wear resistance (hereinafter referred to as “wear ring”) is cast. A ring groove is formed in this wear-resistant ring. For example, in the case of an aluminum piston, first, a wear-resistant ring made of heat-resistant cast iron (high Ni austenitic cast iron) or the like is aluminized. That is, the wear-resistant ring is immersed in molten aluminum or an aluminum alloy, and aluminum is diffused and penetrated into the surface layer of the wear-resistant ring. Next, the wear-resistant ring is held in a casting mold (mold), a molten aluminum is cast into the casting mold, and the wear-resistant ring is cast with aluminum. At this time, since the surface layer of the wear-resistant ring is rich in aluminum due to the previous aluminizing, the surface layer of the wear-resistant ring and the molten aluminum are bonded (fusion-bonded) well, and the wear-resistant ring is bonded and cast well. The rare casting is molded.

Also known are an aluminizing method and a cast-in method that makes it easy to remove a cast-in member such as a wear-resistant ring from the holder and that allows the cast-in member to be accurately and easily held in the mold. (For example, refer to Patent Document 1).
JP-A-11-179521

  By the way, in order to perform aluminizing, not only a dedicated melting furnace and a molten metal furnace are required, but also the processing after aluminizing is complicated and requires time and labor. For example, when holding an aluminized wear-resistant ring in the casting mold, the wear-resistant ring that is wet with molten aluminum at a high temperature is held in the casting mold. In fact, safety must be ensured and automation is difficult.

  Furthermore, the diffusion and permeation layer of aluminum by aluminizing improves the thermal conductivity and mechanical strength due to the diffusion bond between iron and aluminum, but it has the disadvantage that it is not strong in impact, that is, toughness and may become brittle. Have For this reason, when the diffusion-penetrating layer becomes thick, the fragile region also becomes large, and there is a possibility that the bond with a cast metal such as aluminum is broken (peeled). For this reason, it is necessary to appropriately control and manage the thickness of the diffusion and permeation layer by aluminizing, and manufacturing management requires a great deal of time and labor.

  Therefore, the present invention provides a cast-in method capable of casting a cast-in member in a good and easy manner when the cast-in member and the cast metal for casting the same are different materials. Objective.

  In order to achieve the above object, the invention according to claim 1 is a cast-in method in which a cast-in member and a cast metal in which the cast-in member is cast are different materials, and preheating the cast-in member. The cast metal is cast into the mold in a state where ultrasonic vibration is applied to the cast walnut member from a plurality of directions so that the entire cast walnut member vibrates uniformly. And

  According to the present invention, since the cast metal is cast in a state where ultrasonic vibration is applied to the cast walnut member, the cast metal diffuses and penetrates into the surface of the cast walnut member by vibration energy due to ultrasonic waves, and the cast metal is solidified. Along with this, the to-be-cast member and the cast metal are joined.

  According to a second aspect of the present invention, in the cast-in method according to the first aspect, ultrasonic vibration is applied to the cast-in member from at least two opposing directions.

  The invention according to claim 3 is the cast-in method according to claim 1 or 2, wherein the frequency of the ultrasonic vibration is set so that the bonding layer between the cast-in member and the cast metal has a predetermined thickness. It is characterized in that at least one of the amplitude and the application time is adjusted.

  According to a fourth aspect of the present invention, in the cast-in method according to the third aspect, when the cast walnut member is made of heat-resistant cast iron and the cast metal is aluminum or an aluminum alloy, the thickness of the bonding layer is 1 μm. It is characterized by being less than 15 micrometers above.

  According to a fifth aspect of the present invention, in the cast-in method according to any one of the first to fourth aspects, the cast metal constitutes a piston of an internal combustion engine, and the cast-down walnut member constitutes a ring groove portion in which a piston ring is mounted. It is characterized by that.

  According to the first aspect of the present invention, the cast metal diffuses and permeates into the surface of the cast walnut member, and a diffusion / penetration layer (bonding layer) is formed on the surface of the cast walnut member. Good (strong) bonding with the cast metal. Moreover, since ultrasonic vibration is applied so that the entire cast walnut member vibrates uniformly, a diffusion / penetration layer is formed on the entire surface of the cast walnut member, and the entire cast walnut member is well bonded to the cast metal. Is done. Further, the cast stuffed member can be easily cast only by casting the cast metal in a state where ultrasonic vibration is applied to the cast stuffed member from a plurality of directions. That is, a dedicated melting furnace is required, and good casting can be performed without performing aluminizing which is complicated and requires a lot of time and labor.

  According to the second aspect of the present invention, ultrasonic vibration is applied to the cast walnut member from at least two opposing directions, so that the entire cast walnut member is vibrated uniformly. It is possible to perform good cast-in by applying ultrasonic vibration to the surface.

  According to the invention described in claim 3, by adjusting the frequency, amplitude, and application time of the ultrasonic vibration, the bonding layer between the cast walnut member and the cast metal has a predetermined thickness, so that the bonding strength is appropriate. It becomes possible to. That is, if the joining layer is too thick, the cast walnut member and the cast metal may be peeled off due to the brittleness thereof, and the joining layer is controlled to a predetermined thickness (thin), so that the cast walnut member and the cast metal are cast. It is possible to prevent peeling from the metal and make the bonding strength appropriate.

  Further, when the cast walnut member is made of heat-resistant cast iron and the cast metal is aluminum or an aluminum alloy, as a result of investigation and research by the present inventor, the thickness of the bonding layer is set to 1 μm or more and less than 15 μm. It has been confirmed that peeling between the metal and the cast metal is prevented and the bonding strength is appropriate. For this reason, according to the invention described in claim 4, it is possible to prevent the cast-in member and the cast metal from being separated from each other, and to make the bonding strength appropriate.

  According to the fifth aspect of the present invention, the cast metal constitutes the piston of the internal combustion engine, the cast stuffed member constitutes the ring groove, and the piston that is the cast metal and the ring groove that is the cast stuffed member are good. To be joined. For this reason, the ring groove portion does not detach from the piston even under high temperature and pressure, and the ring groove portion functions permanently.

  The present invention will be described below based on the illustrated embodiments.

  FIG. 1 is a flowchart showing a cast-in method according to an embodiment of the present invention. This cast-in method is for a case where a cast-in member and a cast metal in which the cast-in member is cast are different materials and different metals. This is a cast-in method. In this embodiment, the cast walnut member is made of a heat-resistant cast iron (high-Ni austenitic cast iron) wear-resistant ring, the cast metal is aluminum, and the piston for an aluminum diesel engine (internal combustion engine) in which the wear-resistant ring is arranged is cast. The case where it does is demonstrated. That is, a case where aluminum constitutes a piston of an internal combustion engine, a ring groove for mounting the piston ring on the wear resistant ring is formed, and the wear resistant ring constitutes a ring groove portion will be described.

  First, a raw material (aluminum ingot, etc.), which is a cast metal, is melted in a melting furnace (step S1), and molten metal treatment such as degassing treatment or reforming treatment is performed (step S2), and then the molten aluminum melt is melted from the melting furnace. It moves to a holding furnace (step S3). On the other hand, the wear ring is heated (preheated) to about 200 to 300 ° C. in an atmospheric furnace (step S4), and the wear ring 1 is placed at a predetermined position in the casting mold (mold) 2 as shown in FIG. (Step S5).

  Next, a vibrator of an ultrasonic oscillator is attached to the wear-resistant ring 1 (step S6). At this time, the vibrator is attached so that the entire wear-resistant ring 1 vibrates uniformly. Specifically, as shown in FIG. 3, the vibrators 10 are respectively attached to the annular wear-resistant ring 1 at point-symmetric positions (opposite positions) around the center of the wear-resistant ring 1. The reason why the vibrator 10 is attached to two opposing positions in this way and ultrasonic vibration is applied to the wear-resistant ring 1 from two directions as will be described later is as follows.

  That is, when vibration is transmitted, resonance occurs at a half wavelength, and therefore, when ultrasonic vibration is applied to the wear-resistant ring 1 from only one direction, a non-vibrating portion that does not vibrate is generated as shown in FIG. As a result, the entire wear-resistant ring 1 does not vibrate uniformly. As a result, the wear-resistant ring 1 and aluminum are not uniformly joined when the molten aluminum 20 described later is cast. For this reason, by applying ultrasonic vibration to the wear-resistant ring 1 alternately from two opposing directions (with a phase difference of 180 degrees), the entire wear-resistant ring 1 is vibrated uniformly.

  Subsequently, the ultrasonic oscillator is activated to apply ultrasonic vibration to the wear-resistant ring 1 (step S7). In this state, as shown in FIG. 5, the molten aluminum 20 is cast into the casting mold 2 (step S7). S8). Here, the frequency of the ultrasonic wave may be a general frequency (20 kHz or more), but a higher frequency is desirable in consideration of the influence of cavitation on the molten aluminum 20. Further, at least one of the frequency, amplitude and application (irradiation) time of the ultrasonic vibration is adjusted so that the bonding layer (diffusion permeation layer) between the wear-resistant ring 1 and aluminum has a predetermined thickness. That is, if the bonding layer is too thick, the wear-resistant ring 1 and aluminum may be peeled off due to its brittleness, and the peeling of the wear-resistant ring 1 and aluminum is prevented by controlling the bonding layer to a predetermined thickness (thin). Thus, the bonding strength can be made appropriate.

Specifically, in the case of a wear ring 1 made of high Ni austenitic cast iron and aluminum or an aluminum alloy, the result of investigation and research by the present inventor is that the thickness of the bonding layer is about 7 μm (1 μm or more and less than 15 μm). It was confirmed that. For this reason, at least one parameter of the frequency, amplitude, and application time of the ultrasonic vibration is adjusted so that the thickness of the bonding layer is about 7 μm. Here, the parameters to be adjusted are determined based on the material, size, and shape of the to-be-cast member (wear ring 1), the material of the cast metal, the molten metal temperature, and the ambient temperature. For example, the adjustment is performed as follows.
Frequency of ultrasonic vibration: 28-50kHz
Amplitude of ultrasonic vibration: 15 μm or less Temperature of molten aluminum: 700 to 800 ° C.

  The application time of ultrasonic vibration is the largest parameter that affects the thickness of the bonding layer. When the application time is long, the bonding layer becomes thick, and when the application time is short, the bonding layer becomes thin.

  Thus, by casting the molten aluminum 20 in a state where ultrasonic vibration is applied to the wear-resistant ring 1, aluminum diffuses and penetrates into the surface of the wear-resistant ring 1 due to vibrational energy due to ultrasonic waves, and as the molten aluminum 20 solidifies. Thus, the wear-resistant ring 1 and aluminum are joined together.

  Next, after the casting is completed, the molten aluminum 20 in the casting mold 2 is cooled and solidified (step S9). Thereafter, the casting (piston) is taken out from the casting mold 2 (step S10), and post-processes such as cooling the casting and cutting the gate are performed (step S11). Here, the post-process also includes machining for forming a ring groove in the wear-resistant ring 1, whereby the wear-resistant ring 1 constitutes a ring groove portion.

  According to such a cast-in method, aluminum, which is a cast metal, diffuses and penetrates the surface of the wear-resistant ring 1, and a diffusion / penetration layer (bonding layer) is formed on the surface of the wear-resistant ring 1. Good (strong) bonding with aluminum. Moreover, since ultrasonic vibration is applied so that the entire wear-resistant ring 1 vibrates uniformly, a diffusion / penetration layer is formed on the entire surface of the wear-resistant ring 1, and the entire wear-resistant ring 1 is well bonded to the solidified aluminum. Further, since the ultrasonic vibration is applied so that the thickness of the bonding layer is about 7 μm by adjusting the frequency, amplitude and application time of the ultrasonic vibration, peeling between the wear resistant ring 1 and the solidified aluminum is prevented. It is possible to make the bonding strength (toughness) appropriate.

  Here, the result of confirming such an effect is shown in FIGS. FIG. 6 shows the result of processing the cast product by the main casting method to the product outer diameter (final piston outer diameter) and performing a red check (penetration flaw test) around the wear-resistant ring 1. FIG. 7 shows the result of cutting this cast product and verifying the joining state between the wear-resistant ring 1 and the solidified aluminum 21 with a microscope. On the other hand, FIG. 8 shows a case where a cast product (hereinafter referred to as “simple cast method”) without ultrasonic vibration and aluminizing is processed to the product outer diameter, and the periphery of the wear-resistant ring 1 is The result of the red check is shown, and FIG. 9 is an enlarged view of FIG.

  As is apparent from FIGS. 8 and 9, in the simple cast-in method, there are many gaps (red dyeing) between the wear-resistant ring 1 and the solidified aluminum 21, and the gaps are large, that is, the two are not joined. confirmed. On the other hand, in this cast-in method, as shown in FIG. 6, it was confirmed that there was no gap between the wear-resistant ring 1 and the solidified aluminum 21, and the wear-resistant ring 1 and the solidified aluminum 21 were well bonded. . Furthermore, as shown in FIG. 7, it was confirmed that a bonding layer (diffusion permeation layer) 1A was formed on the surface of the wear-resistant ring 1, and the thickness of the bonding layer 1A was 5 to 7 μm. That is, it was confirmed that the bonding strength (toughness) is appropriate and that the wear-resistant ring 1 and the solidified aluminum 21 are prevented from peeling off. On the other hand, when the molten aluminum 20 is cast after the wear resistant ring 1 is aluminized, it is confirmed that the thickness of the bonding layer 1A is about 15 to 20 μm.

  Moreover, the wear resistant ring 1 can be cast easily and appropriately simply by casting the molten aluminum 20 in a state where ultrasonic vibration is applied to the wear resistant ring 1 from two directions. In other words, a special melting furnace or the like is required, and it is possible to perform the casting of dissimilar materials (dissimilar metals) satisfactorily without performing aluminizing which is complicated and requires a lot of time and labor. As a result, it is possible to simplify the process and reduce manufacturing energy and manufacturing cost.

  Although the embodiment of the present invention has been described above, the specific configuration is not limited to the above embodiment, and even if there is a design change or the like without departing from the gist of the present invention, Included in the invention. For example, in the above embodiment, ultrasonic vibration is alternately applied to the wear-resistant ring 1 from two opposing directions. However, depending on the shape, size, material, etc. of the cast stuffed member, three or more Ultrasonic vibration may be applied from the direction so that the entire cast-in member is vibrated uniformly. Moreover, although the case where the wear-resistant ring 1 was cast was described, it is needless to say that the present invention can be applied to other cast members.

  As described above, the cast-in method according to the present invention can cast the cast-in member in a good and easy manner even if the cast-in member and the cast metal for casting the same are different materials. This is extremely useful.

It is a flowchart which shows the casting method which concerns on embodiment of this invention. FIG. 2 is a diagram showing a state in which a wear-resistant ring is placed in a casting mold in the cast-in method of FIG. 1. FIG. 2 is a view showing a state in which a vibrator is attached to a wear-resistant ring in the cast-in method of FIG. 1. FIG. 4 is a diagram showing a state in which only one vibrator is attached to the wear-resistant ring and a vibration state given to the wear-resistant ring in that case. FIG. 2 is a view showing a state in which molten aluminum is cast into a casting mold in the cast-in method of FIG. 1. It is a photograph which shows the result of having carried out the red check of the periphery of the wear-resistant ring by the cast-in method of FIG. It is the photograph (a) which shows the result of having cut | disconnected the periphery of the wear-resistant ring by the cast-in method of FIG. It is a photograph which shows the result of having carried out the red check of the periphery of the wear-resistant ring by a simple cast-in method. It is a partially enlarged photograph of FIG.

Explanation of symbols

1. Wear-resistant ring (cast cast member)
1A Bonding layer 2 Casting mold (mold)
20 Molten aluminum (cast metal)
10 vibrator 21 solidified aluminum (cast metal)

Claims (5)

A cast walnut method in which a cast stuffed member and a cast metal that casts this are different materials,
The cast metal is preheated and held in a mold, and the cast metal is applied in a state where ultrasonic vibration is applied to the cast walnut member from a plurality of directions so that the entire cast walnut member vibrates uniformly. A casting method characterized by casting into a mold.   2. The cast-in method according to claim 1, wherein ultrasonic vibration is applied to the cast-in member from at least two opposing directions.   The frequency, amplitude, and application time of the ultrasonic vibration are adjusted so that the joining layer between the cast stuffed member and the cast metal has a predetermined thickness. The cast-in method of any one of Claims.   4. The cast-in method according to claim 3, wherein when the cast-in member is made of heat-resistant cast iron and the cast metal is aluminum or an aluminum alloy, the thickness of the bonding layer is 1 μm or more and less than 15 μm. . The cast-in method according to any one of claims 1 to 4, wherein the cast metal constitutes a piston of an internal combustion engine, and the cast-in stuffed member constitutes a ring groove portion in which a piston ring is mounted. .