WO2022039540A1 - Titanium insert sleeve of electromagnetic stirring high-pressure casting device - Google Patents

Abstract

Provided is a titanium insert sleeve of an electromagnetic stirring high-pressure casting device, comprising: a cylindrical main body portion having a hollow body; an insert portion coupled to the inner surface of the main body portion and having a hollow in which a plunger tip moves; and a flange for coupling the insert portion to the inner surface of the main body portion so as to be fixed thereto, wherein the insert portion is made of titanium or a titanium alloy, and wear due to dissolution loss is suppressed.

Description

Titanium insert sleeve of electromagnetic stirring high pressure casting device

The present invention relates to a titanium insert sleeve of an electromagnetic stirring high-pressure casting device, and relates to a titanium insert sleeve of an electromagnetic stirring high-pressure casting device capable of minimizing dissolution loss due to molten metal, improving the quality of the casting, and improving the lifespan.

High-pressure casting refers to a method in which molten metal is press-fitted into a mold having a predetermined hollow part shape, and the molten metal is pressurized until it solidifies. High-pressure casting is widely used because of its advantages such as improvement of dimensional precision, maintenance of surface smoothness, reduction in cutting processing, and high-speed mass production.

The high-pressure casting device includes a mold and a sleeve and a plunger for injecting molten metal into the mold. 1a is a cross-sectional view showing a part of a general high-pressure casting apparatus. Referring to FIG. 1a, a sleeve 1 having a cylindrical hollow part is coupled to a mold 3, and a molten metal 7 inside the sleeve 1 This is injected The plunger 5 moves the inside of the sleeve 1 and presses the molten metal 7 introduced into the hollow part of the sleeve to press-fit the molten metal into the mold 3 to manufacture a casting.

Recently, among the methods of high-pressure casting, an electromagnetic stirring high-pressure casting method using electromagnetic waves has been developed. Unlike a general casting device, electromagnetic magnets are arranged in a circumference around the sleeve, and electromagnetic force is applied to the molten metal, which is a paramagnetic substance, injected into the sleeve for a period of several seconds to several tens of seconds.

The injection sleeve, which can be said to be a key part of the electronic stirring high-pressure casting device, plays the role of a cylinder that injects molten metal of a paramagnetic material such as aluminum molten metal at high pressure into the mold. By suppressing and refining the structure, castings with excellent mechanical properties can be manufactured.

However, due to electromagnetic force, vortex and bubble generation may occur in the molten aluminum inside the injection sleeve, causing dissolution loss (A in Fig. 1B) on the inner wall of the sleeve. In addition, since the electronic stirring high-pressure casting device takes about 5 times as long as the time required to keep the molten metal in the sleeve for electromagnetic stirring compared to the general high-pressure casting device, the dissolution loss of the injection sleeve may occur more, thereby shortening the life of the sleeve. There are possible problems. Therefore, it is required to develop a technology capable of minimizing the dissolution loss of the titanium insert sleeve of the electromagnetic stirring electromagnetic stirring high-pressure casting device.

[Prior art literature]

(Patent Document 0001) Korean Patent No. 10-2121979 (Registration Date: 2020. 06. 05)

(Patent Document 0002) Korean Patent Registration No. 10-1253605 (Registration Date: 2013.03.04)

The technical problem to be achieved by the present invention is to provide a titanium insert sleeve of an electromagnetic stirring high-pressure casting device capable of improving the quality of castings by minimizing dissolution loss due to molten metal by providing an insert part inside the sleeve and improving the lifespan. There is this.

In addition, another technical problem to be achieved by the present invention is to provide a titanium insert sleeve of an electromagnetic stirring high-pressure casting device capable of improving the sleeve pinching phenomenon of the plunger tip by setting the tolerance range of the insert part and the plunger tip, respectively. There is this.

Furthermore, another technical object to be achieved by the present invention is to provide a titanium insert sleeve of an electromagnetic stirring high-pressure casting device capable of improving the movement of the plunger tip toward the inside of the sleeve.

The object of the present invention is not limited to the object mentioned above, and other objects not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the following description.

In order to solve the above problem, the present invention provides a cylindrical body portion having a hollow, an insert portion coupled to the inner surface of the main body portion and having a hollow in which the plunger tip moves, and the insert portion is located on the inner surface of the main body portion. It is possible to provide a titanium insert sleeve of an electromagnetic stirring high-pressure casting device comprising a flange coupled to be fixed, wherein the insert portion is made of titanium or a titanium alloy, and wear due to dissolution loss is suppressed.

The sleeve may be one in which the body part and the insert part are hot-fitted.

The body portion may be formed of a diamagnetic material.

In the insert part, a tolerance of an inner diameter may be set by a product of a room temperature linear thermal expansion coefficient of the titanium alloy and a temperature difference between the molten metal and room temperature.

The plunger tip may have an outer diameter tolerance set by a product of a room temperature linear thermal expansion coefficient of the plunger tip and a temperature difference between the molten metal and room temperature.

The flange may have an inclination in which a cross section of an inner circumferential surface is narrowed toward the outside.

The titanium insert sleeve of the electromagnetic stirring high-pressure casting apparatus according to an embodiment of the present invention is provided with an insert of titanium or titanium alloy coupled to the inside of the body to minimize dissolution loss due to molten metal, thereby improving the quality of the casting and improving the lifespan. There are advantages that can be In addition, it is possible to improve the sleeve jamming phenomenon of the plunger tip by setting the tolerance range by reflecting the coefficient of linear thermal expansion of the insert part and the plunger tip and the temperature of the molten metal. This has the advantage of smoothing the movement of the plunger tip toward the inside of the sleeve.

1a is a cross-sectional view showing a part of a general high-pressure casting apparatus;

1b is a cross-sectional view showing a high-pressure casting device sleeve in which dissolution loss occurred;

2 is a perspective view showing a titanium insert sleeve of an electromagnetic stirring high-pressure casting device according to an embodiment of the present invention;

3 is a cross-sectional view taken along II' in FIG. 2;

4 is a perspective view showing a flange of a titanium insert sleeve of an electromagnetic stirring high-pressure casting device according to an embodiment of the present invention;

5 is a diagram showing the phase equilibrium state of Ti-Al.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. And, in the drawings, the length, thickness, etc. of layers and regions may be exaggerated for convenience. Like reference numerals refer to like elements throughout.

Figure 1a is a cross-sectional view showing a part of a general high-pressure casting device, Figure 1b is a cross-sectional view showing a high-pressure casting device sleeve in which dissolution loss occurs, Figure 2 is a titanium insert sleeve of the electromagnetic stirring high-pressure casting device according to an embodiment of the present invention 3 is a cross-sectional view taken along II' of FIG. 2, FIG. 4 is a perspective view showing a flange of a titanium insert sleeve of an electromagnetic stirring high-pressure casting apparatus according to an embodiment of the present invention, and FIG. 5 is Ti-Al It is a diagram showing the phase equilibrium state of

2 to 5 , the titanium insert sleeve 100 of the electromagnetic stirring high-pressure casting apparatus according to the embodiment of the present invention includes a body portion 110 , an insert portion 120 , and a flange 130 . can

The body portion 110 of the titanium insert sleeve 100 may be provided in a cylindrical shape having a hollow. When the titanium insert sleeve 100 is mounted on the electromagnetic stirring high-pressure casting device, the main body 110 may be formed of a diamagnetic material such as austenitic stainless steel in order to prevent the loss of electromagnetic force transmitted to the molten metal, which is a paramagnetic material. there is. For example, after centrifugally casting austenitic stainless steel as a material to produce a hollow cylinder, annealing for stress relief is performed, and after roughing the inner and outer diameters, a hole for inserting a thermocouple or a hole for assembling (110h) The body portion 110 may be formed by performing processing such as forming.

The insert part 120 is inserted into the inner surface of the body part 110, is coupled to the front surface, and may have a hollow 125 in which the plunger tip moves. For example, the insert unit 120 may be provided by forming a hollow through inner diameter drilling of a bar material, and then performing inner and outer diameter side cutting and outer diameter grinding.

The titanium insert sleeve 100 may be one in which the body part 110 and the insert part 120 are hot-fitted. That is, after heating the body part 110 , the insert part 120 is placed inside the body part 110 , and by cooling the body part 110 , the body part 110 and the insert part 120 are in close contact with each other. can be combined. After hot fitting of the insert part 120 , after inner diameter finishing and inner diameter honing, the titanium insert sleeve 100 may be manufactured by grinding the outer diameter and assembling the flange 130 .

Furthermore, since the insert part 120 is made of titanium or a titanium alloy, it is strong even when the temperature rises and falls, so that wear due to dissolution loss can be suppressed. When a steel type containing iron as a main component is applied to the insert sleeve as in the prior art, the high-temperature molten aluminum and iron contained in the sleeve react to generate metal compounds such as FeAl ₃ , Fe ₂ Al ₃ . The iron and aluminum compound is very brittle and may cause dissolution loss from the sleeve surface.

However, titanium or titanium alloy has excellent properties at high temperature, and the insert part 120 in contact with the molten metal is formed to include titanium or titanium alloy, thereby suppressing wear due to dissolution loss of the titanium insert sleeve 100 . For example, the titanium alloy may include Ti6Al4V. Ti6Al4V has a high melting point of 1680°C, which has a large difference from the molten metal temperature of about 700°C, and has excellent properties such as strength, toughness, corrosion resistance, and thermal conductivity at high temperatures.

Since the titanium included in the insert part 120 can continuously form a passivation film, a titanium dioxide film, as an oxide film by reacting with oxygen, direct contact between the molten aluminum and the insert part 120 material can be blocked. In addition, the titanium dioxide film may be partially destroyed by the high-temperature aluminum molten metal, but due to this, Al ₂ O ₃ is formed by the reaction of oxygen and aluminum in the 600° C. region, and the surface of the insert part 120 due to the reaction of titanium and aluminum TiAl ₃ compound formation may be induced (see FIG. 5). The TiAl ₃ compound has a body centered tetragonal crystal structure, has high strength, high corrosion resistance, and high toughness, and is in a stable state without a reaction mechanism with aluminum. Therefore, since the insert part 120 including the titanium alloy may further have a surface in a stable state without reacting with the molten metal, it is possible to suppress the loss of dissolution due to the molten metal.

That is, in the electromagnetic stirring high-pressure casting method, the titanium insert sleeve 100 according to the embodiment of the present invention is made of titanium or a titanium alloy even if the cycle of maintaining the aluminum molten metal at about 700° C. for 25 to 30 seconds is continuously repeated. Dissolution loss can be minimized by the insert unit 120 , the quality of the casting can be improved, and the lifespan of the titanium insert sleeve 100 can be improved. Furthermore, even if dissolution loss occurs due to long-term use, since only the insert part 120 needs to be replaced, maintenance costs are reduced.

The plunger tip moves the inside of the titanium insert sleeve 100 , that is, the hollow 125 of the insert part 120 , and injects and pressurizes molten metal into the mold. The tip does not work, which can cause problems with the injection of the product. This can be attributed to the difference in the coefficient of thermal expansion between the insert part 120 and the plunger tip.

Therefore, in order to solve the operation problem due to the pinching of the plunger tip during injection of the manufactured product, the insert part 120 is the product of the room temperature linear thermal expansion coefficient of the titanium alloy and the temperature difference between the molten metal and the room temperature. can Further, the plunger tip may be one in which the tolerance of the outer diameter is set by the product of the room temperature linear thermal expansion coefficient of the plunger tip and the temperature difference between the molten metal and the room temperature.

At this time, when the interval between the tolerance of the inner diameter of the insert part 120 and the tolerance of the outer diameter of the plunger tip increases, that is, when the difference between the maximum value of the inner diameter of the insert part 120 allowed in the tolerance and the minimum value of the outer diameter of the plunger tip is large, the plunger The tip may be eccentric. Therefore, it is preferable that the tolerance of the inner diameter of the insert part 120 and the tolerance of the outer diameter of the plunger tip reflects the difference between the maximum value of the inner diameter of the insert part 120 and the minimum value of the outer diameter of the plunger tip.

Therefore, reflecting the above tolerance range to prevent pinching of the plunger tip and eccentricity of the plunger tip, the insert part 120 may have an inner diameter tolerance of 0.10 × A1 to 0.22 × A1 from A1 below. , The plunger tip may have an outer diameter tolerance of -0.05×A2 to 0.02×A2 from A2 below.

A1=(Standard dimension of insert inner diameter (mm))×(Coefficient of thermal expansion at room temperature of titanium alloy)×(Temperature of molten metal (℃) - Room temperature (℃)) --------(1)

A2=(Standard dimension of insert inner diameter (mm))×(Coefficient of thermal expansion at room temperature of plunger tip material)×(Temperature of molten metal (℃) - Room temperature (℃)) -------(2)

As an experimental example, the insert part 120 was manufactured using a Ti6Al4V titanium alloy having a coefficient of linear thermal expansion of 8.6 * 10 ^-6 /℃ with a reference dimension of the inner diameter of the insert part 120 as 95 mm, and 700 at 25 ℃ room temperature An injection process was performed by injecting molten metal at °C into the titanium insert sleeve 100 . At this time, a plunger tip was manufactured using SKD61 having a coefficient of linear thermal expansion of 1.25*10 ^-5 /°C at room temperature. For a sleeve inner diameter of 95 mm reflecting A1 and A2, the tolerance of the sleeve inner diameter was 0.05 to 0.12, and the tolerance of the plunger tip outer diameter was calculated as -0.04 to 0.016.

The sleeve inner diameter tolerance and the plunger tip outer diameter tolerance were measured with respect to the standard dimension of 95 mm of the inner diameter of the insert part 120, and the results for the normal operation are shown in Table 1 below.

	Sleeve Tolerance	Plunger tip tolerance	jamming	eccentricity
Example 1	0.07	-0.01	does not exist	does not exist
Example 2	0.10	-0.01	does not exist	does not exist
Example 3	0.08	-0.03	does not exist	does not exist
Example 4	0.08	0	does not exist	does not exist
Comparative Example 1	0.03	-0.01	has exist	-
Comparative Example 2	0.05	0.02	has exist	-
Comparative Example 3	0.15	-0.01	does not exist	has exist
Comparative Example 4	0.13	-0.06	does not exist	has exist

Among the actually inserted insert sleeves, when the inner diameter of the sleeve was out of the tolerance range (Comparative Example 1), and when the inner diameter of the sleeve was within the tolerance range but the plunger tip outer diameter was out of the tolerance range (Comparative Example 2), the plunger tip was caught. If the plunger tip is within the tolerance range, but the inner diameter of the insert part 120 is out of the tolerance range and the difference between the inner diameter of the insert part 120 and the plunger tip outer diameter is large (Comparative Example 3), both the inner diameter of the sleeve and the outer diameter of the plunger tip are out of the tolerance range When the difference between the inner diameter of the back insert part 120 and the outer diameter of the plunger tip is large (Comparative Example 4), the eccentricity of the plunger tip occurred. Therefore, the insert part 120 and the plunger tip can improve the defect caused by pinching of the plunger tip and the eccentricity of the plunger tip by setting tolerances by reflecting the respective room temperature linear thermal expansion coefficients and the temperature of the molten metal.

The flange 130 may couple the insert part 120 and the body part 110 so that the insert part 120 is fixed to the inner surface of the body part 110 . For example, for coupling with the flange 130 and the body part 110, a flange coupling hole 130h is provided at a position corresponding to the body part assembly hole 110h, and the fastener is for body part assembly. By coupling the hole 110h and the flange coupling hole 130h through the coupling, the flange 130 and the body part 110 are coupled to fix the insert part 120 . Therefore, even if dissolution loss occurs due to long-term use, since only the insert part 120 needs to be replaced by releasing the flange 130 , there is an effect of reducing the maintenance cost. At this time, the fastener is preferably provided with a strong assembly bolt 132 so as not to be separated even if the insert portion 120 is deformed by heating and cooling.

In addition, the flange 130 may have an inclination in which the cross section of the inner circumferential surface 134 is narrowed toward the outside. Therefore, by providing the shape of the inlet part into which the plunger tip is inserted is slightly wider than the inside of the titanium insert sleeve 100, that is, the inside of the insert part 120, the movement of the plunger tip toward the inside of the titanium insert sleeve 100 can be smooth. there is. In this case, the slope angle θ, which is the inclination at which the cross section of the inner circumferential surface 134 is narrowed toward the outside, is preferably in the range of 10 to 12° so as not to deviate from the titanium insert sleeve 100 during the reciprocating motion of the plunger tip.

The titanium insert sleeve 100 of the electromagnetic stirring high-pressure casting apparatus according to the embodiment of the present invention includes the insert part 120 coupled to the inside of the body part 110 with titanium or titanium alloy to minimize dissolution loss due to molten metal. It has the advantage of improving the quality of the product and improving its lifespan. In addition, it is possible to improve the insert sleeve pinching phenomenon of the plunger tip by setting the tolerance range by reflecting the linear thermal expansion coefficient of the insert part 120 and the plunger tip and the temperature of the molten metal, and furthermore, the inlet part into which the plunger tip is inserted By providing a gradient in the injection sleeve 100, there is an advantage in that the movement of the plunger tip toward the inside becomes smooth.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that it can be done.

[Explanation of code]

100; Titanium insert sleeve

110; body part

110h; body assembly hole

120; insert part

125; hollow

130; flange

130h; hole for flange coupling

θ; draft angle

Claims (6)

1. A cylindrical body portion having a hollow, and

   an insert portion coupled to the inner surface of the body portion and having a hollow in which the plunger tip moves;

   and a flange coupling the insert part to be fixed to the inner surface of the body part,

   The insert part is made of titanium or a titanium alloy, and a titanium insert sleeve of an electromagnetic stirring high-pressure casting device, characterized in that wear due to dissolution loss is suppressed.
2. The method of claim 1,

   The titanium insert sleeve is a titanium insert sleeve of an electromagnetic stirring high-pressure casting device, characterized in that the body portion and the insert portion are coupled by hot fitting.
3. The method of claim 1,

   The titanium insert sleeve of the electromagnetic stirring high-pressure casting device, characterized in that the main body is formed of a diamagnetic material.
4. The method of claim 1,

   The insert part, a titanium insert sleeve of an electromagnetic stirring high-pressure casting device, characterized in that the tolerance of the inner diameter is set by the product of the room temperature linear thermal expansion coefficient of the titanium alloy and the temperature difference between the molten metal and room temperature.
5. The method of claim 1,

   The plunger tip is a titanium insert sleeve of an electromagnetic stirring high-pressure casting device, characterized in that the tolerance of the outer diameter is set by the product of the room temperature linear thermal expansion coefficient of the plunger tip and the temperature difference between the molten metal and room temperature.
6. The method of claim 1,

   The flange is a titanium insert sleeve of an electromagnetic stirring high-pressure casting device, characterized in that it has a slope in which the cross section of the inner circumferential surface is narrowed toward the outside.

Images