JP7193943B2 - sleeve for die casting - Google Patents

Description

The present invention relates to a sleeve used for filling molten metal into a cavity in a die casting apparatus.

In die casting of non-ferrous metals such as aluminum, magnesium, zinc, tin, lead and their alloys, a cylindrical sleeve is used to fill the cavity with molten metal. One end of the sleeve communicates with the cavity, and the plunger tip enters from the other end and slides in the sleeve in the axial direction. In a horizontal type (horizontal injection type) sleeve that is used with the axial direction substantially horizontal, a pouring hole that penetrates a part of the side peripheral wall of the sleeve opens upward near the end on the side where the plunger tip is inserted. It is designed to Molten metal supplied into the sleeve from the pouring hole is pushed by the plunger tip advancing in the sleeve to fill the cavity.

However, as shown in FIG. 5(a), in the horizontal sleeve 100 used with the axial direction substantially horizontal, the end portion on the pouring hole 130 side warps upward. In the drawing, the amount of deformation d due to warping is exaggerated.

When such deformation occurs, the frictional resistance between the plunger tip 150 traveling straight through the sleeve 100 and the inner peripheral surface of the sleeve 100 increases, as schematically shown in FIG. 5(b). Since the end on the side where the plunger tip 150 enters is warped upward, the frictional resistance greatly increases at the upper portion of the inner peripheral surface of the sleeve 100, and the plunger tip 150 bites into the inner peripheral surface of the sleeve 100. , so-called "galling resistance" occurs. As a result, both the sleeve 100 and the plunger tip 150 are likely to wear out, shortening their service life. In addition, the increased frictional resistance between the sleeve 100 and the plunger tip 150 causes instability in the speed at which the molten metal is injected into the cavity, adversely affecting the quality of the molded product. Therefore, there has been a demand for a die-casting sleeve in which the warp-up deformation of the end portion is suppressed.

Therefore, in view of the above circumstances, it is an object of the present invention to provide a die-casting sleeve that is used with its axial direction substantially horizontal, and in which the warping of the ends is suppressed. .

In order to solve the above problems, the die casting sleeve (hereinafter sometimes simply referred to as "sleeve") according to the present invention is
"It has a cylindrical tube and a pouring hole that penetrates a part of the side peripheral wall of the tube, and the front end is communicated with the cavity in a state where the axial direction is substantially horizontal, and the plunger chip is entered from the rear end. A die-casting sleeve that allows
The cylindrical portion has an outer cylinder and an inner cylinder fitted into the outer cylinder,
The inner cylinder has an upper wall portion formed of a first material at least from the periphery of the pouring hole to the rear end, and has a second wall portion from at least directly below the pouring hole to the rear end. having a lower wall made of two materials,
The second material has a smaller coefficient of thermal expansion than the first material.

It is thought that the warped deformation of the end of the sleeve that is used with the axial direction substantially horizontal occurs as follows. That is, when high-temperature molten metal is supplied from the pouring hole, the temperature immediately below, which is the portion that receives the molten metal, becomes extremely high. When the molten metal is supplied from the pouring hole, the liquid surface of the molten metal does not reach the upper part of the inner peripheral surface of the inner cylinder, so the peripheral edge of the pouring hole, which is the part directly below, does not become very hot. . As a result, while the immediately lower portion and the vicinity thereof, which have reached a very high temperature, undergo large thermal expansion, the degree of thermal expansion is small in the peripheral portion of the pouring hole that faces them. As a result, while the immediately lower portion and its vicinity extend greatly in the axial direction due to thermal expansion, the peripheral edge portion of the opposing pouring hole does not extend so much in the axial direction. It deforms so as to warp toward

Therefore, in the present invention, the lower wall portion is formed of a second material with a small thermal expansion coefficient from the immediately lower portion, which is the portion where the temperature is the highest due to heating by the molten metal, to the rear end where the plunger enters, and the sleeve has a lower wall portion. A configuration is employed in which the peripheral edge portion of the pouring hole, which is a portion facing the direct lower portion and does not reach as high a temperature as the direct lower portion, is the upper wall portion formed of a first material having a larger coefficient of thermal expansion than the second material. As a result, it is possible to balance the thermal expansion of the portion immediately below and in the vicinity thereof with the thermal expansion of the peripheral portion of the pouring hole, thereby suppressing the warping deformation of the end portion on the pouring hole side.

In addition to the above configuration, the die casting sleeve according to the present invention has
"The second material has a lower thermal conductivity than the first material."

Before the molten metal supplied from the pouring hole into the sleeve reaches the cavity, if the temperature drops inside the sleeve and solidified pieces are generated, defects such as peeling are likely to occur in those areas in the molded product. Decrease in mechanical strength. In this configuration, as the second material forming the lower wall portion, which is the main portion in contact with the molten metal, a material having a lower thermal conductivity than the first material forming the upper wall portion is used. Therefore, the lower wall portion, which is the main portion that comes into contact with the molten metal, has high heat retention, and suppresses the temperature drop of the molten metal.

In addition to the above configuration, the die casting sleeve according to the present invention has
It is possible that "the lower wall portion has a length covering the entire length of the inner cylinder in the axial direction".

Molten metal supplied into the sleeve from the pouring hole is pushed by the plunger tip and moves to the front end of the inner cylinder. That is, the lower portion of the inner peripheral wall of the inner cylinder contacts the molten metal over the entire axial length of the inner cylinder. Therefore, in this configuration in which the lower wall portion that is continuous with the bottom portion of the pouring hole extends over the entire length of the inner cylinder in the axial direction, almost the entire portion that contacts the molten metal is the second Since elongation due to thermal expansion is well suppressed by being formed of a material, upward warping deformation is effectively suppressed. In addition, when the thermal conductivity of the second material is lower than that of the first material, almost the entire portion in contact with the molten metal has high heat retention, so there is an advantage that the effect of suppressing the temperature drop of the molten metal is higher. .

In addition to the above configuration, the die casting sleeve according to the present invention has
"The height of the boundary between the upper wall portion and the lower wall portion gradually increases from the rear end toward the front end".

The liquid level of the molten metal supplied into the sleeve from the pouring hole rises as the molten metal pushed by the plunger tip moves toward the front end. In other words, the height of the portion of the inner peripheral wall of the inner cylinder that contacts the molten metal increases from the rear end toward the front end. In this configuration, the height of the upper end of the lower wall portion is gradually increased from the rear end to the front end in accordance with the rise in the height of the portion that contacts the molten metal. Therefore, since the entire portion that comes into contact with the molten metal is made of the second material with a small thermal expansion coefficient, elongation due to thermal expansion is better suppressed, so upward warping deformation is more effective. Suppressed. In addition, when the thermal conductivity of the second material is lower than that of the first material, there is an advantage that the effect of suppressing the decrease in the temperature of the molten metal is even higher due to the high heat retention of the entire portion in contact with the molten metal. .

As described above, according to the present invention, it is possible to provide a die-casting sleeve that is used with its axial direction substantially horizontal, and in which deformation in which the ends are warped up is suppressed.

FIG. 1(a-1) is a cross-sectional view of the sleeve of the first embodiment cut in the axial direction at the center, FIG. 1(a-2) is a cross-sectional view along line A1-A1, and FIG. ) is a sectional view taken along line A2-A2. FIG. 1(b-1) is a cross-sectional view of the sleeve of the second embodiment cut in the axial direction at the center, FIG. 1(b-2) is a cross-sectional view along line B1-B1, and FIG. ) is a sectional view taken along line B2-B2. FIG. 1(c-1) is a cross-sectional view of the sleeve of the third embodiment taken along the axial direction, FIG. 1(c-2) is a cross-sectional view taken along line C1-C1, and FIG. ) is a sectional view taken along line C2-C2. FIGS. 2(a) to 2(c) are explanatory diagrams for manufacturing the sleeve of the second embodiment. FIG. 3(a) is a graph plotting the amount of displacement of the sleeves of the example and the comparative example against time, and FIG. It is a graph plotted against. FIG. 4(a) is a cross-sectional view taken axially at the center of the sleeve when the molten metal is supplied from the pouring hole, and FIG. 4(b) is the molten metal moved by being pushed by the plunger tip. FIG. 4 is a cross-sectional view taken axially at the center of the sleeve in a folded state; FIG. 5(a) is a schematic diagram showing deformation in a conventional sleeve, and FIG. 5(b) is a schematic diagram for explaining galling resistance in the conventional sleeve.

Hereinafter, sleeves 1 , 2 and 3 of specific embodiments will be described with reference to the drawings. The sleeves 2 and 3 of the second and third embodiments are embodiments of the present invention, and the sleeve 1 of the first embodiment is a reference example. The points are descriptions of embodiments of the present invention. First, the sleeve 1 of the first embodiment will be described with reference to FIGS. 1(a-1) to 1(a-3). The sleeve 1 is a sleeve for a die-casting device, and has a cylindrical tubular portion and a pouring hole 30 that penetrates a part of the side peripheral wall of the tubular portion. is communicated with the cavity, and the plunger tip enters from the rear end E2.

The cylindrical portion has an outer cylinder 20 and an inner cylinder 10 fitted in the outer cylinder 20 , and the inner cylinder 10 is composed of an upper wall portion 11 and a lower wall portion 12 . The upper wall portion 11 is made of the first material, and is provided at least from the periphery of the pouring hole 30 to the rear end E2. The lower wall portion 12 is made of the second material, and is provided at least from directly below UN of the pouring hole 30 to the rear end E2. The pouring hole 30 is provided in the vicinity of the rear end E2 in the cylindrical portion. The pouring hole 30 is opened upward while the axial direction of the sleeve 1 is horizontal.

More specifically, the outer cylinder 20 is cylindrical and made of steel. The inner cylinder 10 is also cylindrical, and is shrink-fitted in the outer cylinder 20 with the upper wall portion 11 and the lower wall portion 12 butted against each other. In the sleeve 1, the upper wall portion 11 and the lower wall portion 12 each have a shape and size corresponding to a semi-cylinder obtained by cutting the cylindrical inner cylinder 10 at the center in the axial direction. That is, in the sleeve 1 , the upper wall portion 11 extends not only from the periphery of the pouring hole 30 to the rear end E2 of the inner cylinder 10 but also over the entire length L of the inner cylinder 10 in the axial direction. The lower wall portion 12 also has a length extending not only from the portion UN directly below the pouring hole 30 to the rear end E2 of the inner cylinder 10 but also over the entire length L of the inner cylinder 10 in the axial direction. Of course, the height h from the lower end of the inner cylinder 10 to the boundary between the upper wall portion 11 and the lower wall portion 12 is constant over the entire length L of the inner cylinder 10 in the axial direction, and the outer diameter of the inner cylinder 10 is It is one-half of R.

The upper wall portion 11 is made of SKD61, which is the first material. On the other hand, the lower wall portion 12 is made of a composite material (hereinafter referred to as "TC composite material") of titanium or a titanium alloy, which is the second material, and ceramics. The TC composite material of the present embodiment is produced by powder metallurgy, and is obtained by firing a compact formed from a raw material mixture of titanium powder, silicon carbide powder, and nickel powder in a non-oxidizing atmosphere. It is a thing.

The coefficient of thermal expansion of SKD61, which is the first material, is 10.7×10 ⁻⁶ /° C., while the coefficient of thermal expansion of the TC composite material, which is the second material, is 7.4×10 ⁻⁶ /° C. and is smaller than the first material. In this embodiment, the portion of the inner cylinder 10 that contacts the molten metal, that is, the portion UN directly below that receives the molten metal supplied from the pouring hole 30, and the plunger tip move toward the front end E1 as the plunger tip advances. Almost the entire portion that contacts the molten metal is the lower wall portion 12 made of a second material with a small coefficient of thermal expansion. The upper wall portion 11, which is a portion of the sleeve facing the lower wall portion 12 and is not as hot as the lower wall portion 12, is made of a first material having a higher coefficient of thermal expansion than the second material.

As a result, compared to the case where the lower wall portion 12 and the upper wall portion 11 are made of the same material, the magnitude of thermal expansion of the lower wall portion 12 and the degree of thermal expansion of the upper wall portion 11 when in contact with the molten metal are increased. Since the difference from the magnitude of thermal expansion is small and the thermal expansion of the lower wall portion 12 and the thermal expansion of the upper wall portion 11 can be brought close to a balanced state, the cylindrical portion warps upward on the rear end E2 side. can be suppressed.

In addition, the first material, SKD61, has a high thermal conductivity of 35.6 W/mK, while the second material, TC composite material, has a very low thermal conductivity of 7.4 W/mK. If the temperature of the molten metal supplied into the sleeve from the pouring hole 30 drops in the sleeve before reaching the cavity and a solidified piece is generated, defects such as peeling will occur at that portion in the molded product. It tends to occur and the mechanical strength decreases. In contrast, in the present embodiment, a material having a lower thermal conductivity than the first material forming the upper wall portion 11 is used as the second material forming the lower wall portion 12, which is the main portion that contacts the molten metal. doing. Therefore, the lower wall portion 12, which is the main portion that comes into contact with the molten metal, has high heat retention, and the risk of the temperature of the molten metal falling within the sleeve is reduced.

Further, since the lower wall portion 12 is provided with a length extending over the entire length L in the axial direction of the inner cylinder 10, almost the entire portion that comes into contact with the molten metal is made of the second material with a small coefficient of thermal expansion. Therefore, thermal expansion of the lower wall portion 12 due to being heated by contact with the molten metal is sufficiently suppressed.

In addition, since the lower wall portion 12 extends over the entire length L in the axial direction of the inner cylinder 10, almost the entire portion that contacts the molten metal is made of the second material with low thermal conductivity. Therefore, the drop in the temperature of the molten metal is suppressed while the molten metal moves through the sleeve 1 due to the advancement of the plunger tip.

Furthermore, the second material, TC composite material, has higher corrosion resistance to molten metal than the first material, SKD61. In the sleeve 1 of the present embodiment, SKD61, which has a higher coefficient of thermal expansion than the TC composite material but is inferior to the TC composite material in terms of corrosion resistance, is used as a material for forming a part of the inner cylinder 10. The lower wall portion 12, which is a portion, is made of a TC composite material having high corrosion resistance to ensure corrosion resistance to molten metal.

Next, the sleeve 2 of the second embodiment will be described with reference to FIGS. 1(b-1) to 1(b-3). The difference between the sleeve 2 and the sleeve 1 is that the height h of the boundary between the upper wall portion 11 and the lower wall portion 12, that is, the height h of the upper end of the lower wall portion 12 extends from the rear end E2 of the inner cylinder 10. The point is that it gradually increases toward the front end E1. Specifically, the height h at the rear end E2 of the inner cylinder 10 is 1/4 to 1/2 times the outer diameter R of the inner cylinder 10, and the height h at the front end E1 of the inner cylinder 10 is the inner diameter. It is 1/2 to 3/4 times the outer diameter R of the cylinder 10, and the height h linearly increases from the rear end E2 toward the front end E1.

The sleeve 2 having such a configuration also exhibits the same effects as those described above for the sleeve 1 . In addition, in the sleeve 2, the height h of the upper end of the lower wall portion 12 in the inner cylinder 10 increases from the rear end E2 toward the front end E1. The liquid level of the molten metal supplied into the sleeve from the pouring hole 30 rises as the molten metal pushed by the plunger tip moves toward the front end E1. In this embodiment, the height h of the upper end of the lower wall portion 12 is increased from the rear end E2 toward the front end E1 in accordance with the rise in the liquid level of the molten metal. Therefore, since the portion that comes into contact with the molten metal is entirely made of the second material with a small coefficient of thermal expansion, elongation due to thermal expansion is better suppressed, and upward warping deformation is more effectively suppressed. be.

Further, the temperature of the molten metal is the highest when it is supplied from the pouring hole 30, and the temperature tends to decrease as the molten metal is pushed by the plunger tip and moves toward the front end E1. In contrast, in the present embodiment, the proportion of the side wall of the inner cylinder 10 occupied by the lower wall portion 12 increases from the rear end E2 toward the front end E1. Since the lower wall portion 12 made of the second material having the lower thermal conductivity occupies a larger portion toward the front end E1, heat retention is enhanced toward the front end E1 side of the inner cylinder 10. It is possible to more effectively suppress the decrease in the temperature of the molten metal moving.

Furthermore, the sleeve 2 has the advantage that the inner cylinder 10 can be manufactured using the first material and the second material without waste. This will be explained using FIG. 2. The inner cylinder 10 of the sleeve 2 can be manufactured from a cylinder 50 made of a first material and a cylinder 60 made of a second material. The cylinder 50 has the same outer diameter R as the inner cylinder 10 . On the other hand, the cylinder 60 has the same outer diameter R as the inner cylinder 10 and the same inner diameter as the cylinder 50 . These cylinders 50 and 60 are cut along the same cutting line CL as shown in FIG. 2(a). The cutting line CL at this time is the same as the line along which the height h increases linearly from the rear end E2 toward the front end E1 in the inner cylinder 10 to be manufactured. The left figure in FIG. 2(a) is a side view of the cylinder 50 or the cylinder 60, and the right figure is a sectional view taken along line DD.

By such cutting, the cylinder 50 is divided into two parts 50a and 50b, and when dividing the cylinder 60 into the two parts 60a and 60b, as shown in FIG. Cutting allowance material is lost. In FIG. 2(b), the void S corresponding to the material lost by cutting is exaggerated.

After that, by combining the portion 50a obtained by dividing the cylinder 50 of the first material and the portion 60b obtained by dividing the cylinder 60 of the second material, one inner cylinder 10 is manufactured and the first Another inner cylinder 10 can be manufactured by combining the material portion 50b and the second material portion 60a. In such a combination, as shown in FIG. 2(c), by butting the two parts together while being displaced in the axial direction, the original material is retained despite the loss of material for the cutting allowance. It is possible to manufacture the inner cylinder 10 having the same outer diameter R as the cylinders 50 and 60 and having a perfect circular cross-sectional circle in the direction orthogonal to the axial direction. The left figure in FIG. 2(c) is a side view of a state in which the portion 50a and the portion 60b are combined, and the right figure is a sectional view taken along line EE.

Next, the sleeve 3 of the third embodiment will be described with reference to FIGS. 1(c-1) to 1(c-3). In the sleeves 1 and 2, the upper wall portion 11 has a length that covers the entire length L of the inner cylinder 10 in the axial direction. is shorter than the total length L of . Specifically, the height h at the rear end E2 of the inner cylinder 10 is 1/4 to 1/2 times the outer diameter R of the inner cylinder 10, and the height h gradually increases toward the front end E1. In addition, the height h coincides with the outer diameter R of the inner cylinder 10 at the position of the length N in the axial direction from the front end E1 of the inner cylinder 10 . That is, of the side peripheral wall of the inner cylinder 10, the portion having the length N in the axial direction on the front end E1 side consists only of the lower wall portion 12 formed of the second material.

Here, the length N is such that the maximum length (LN) of the upper wall portion 11 in the axial direction is 3/2 to 3 times the length n of the pouring hole 30 in the axial direction of the inner cylinder 10. can be set to be

With the sleeve 3 having such a configuration, it is possible to obtain the same effects as those described above for the sleeve 1 . In addition, the sleeve 3 is close to the necessary minimum including the periphery of the pouring hole 30, which is a portion where the thermal expansion should be balanced with the immediately below UN, which is the highest temperature due to the molten metal supplied from the pouring hole 30. The range is defined as the upper wall portion 11 formed of the first material having a large coefficient of thermal expansion. As a result, while obtaining the effect of suppressing the deformation that the rear end E2 side warps upward, the remainder serves as the lower wall portion 12, and the space in which the molten metal moves toward the front end E1 is surrounded by the second material with low thermal conductivity. Thereby, a decrease in the temperature of the molten metal can be effectively suppressed.

Further, as shown in FIG. 4A, when the molten metal M is supplied from the pouring hole 30, the liquid level of the molten metal M does not reach the upper part of the inner peripheral wall of the inner cylinder 10. As shown in FIG. 4(b), as it is pushed by the plunger tip 150 and moves toward the front end E1, the liquid level of the molten metal M may reach the top of the inner peripheral wall of the inner cylinder 10. be. The sleeve 3 of this embodiment is suitable for such use. That is, in the sleeve 3, the front end E1 side of the side peripheral wall of the inner cylinder 10 consists only of the lower wall portion 12, and the lower wall portion 12 is formed of the second material having a small coefficient of thermal expansion and thermal conductivity and high corrosion resistance. Therefore, the thermal expansion of the portion of the inner cylinder 10 that contacts the molten metal is suppressed, the corrosion resistance of that portion is enhanced, and the effect of suppressing the temperature drop of the molten metal can be effectively exhibited.

As described above, according to the sleeves 1, 2, 3 of the present embodiment, it is possible to suppress the warping deformation of the rear end E2 side into which the plunger tip enters, and the friction between the sleeves 1, 2, 3 and the plunger tip can be suppressed. As the resistance increases, the extent to which wear progresses in both can be reduced.

In practice, the sleeve of the example and the sleeve of the comparative example were compared in terms of the amount of deformation of the rear end E2 into which the plunger tip enters. In the sleeve of the embodiment, the outer cylinder 20 is made of carbon steel S45C for machine structural use, the inner cylinder 10 is made of the first material SKD61 to form the upper wall part 11, and the second material is the TC composite material to make the lower part. A wall portion 12 was formed. The configuration of the upper wall portion 11 and the lower wall portion 12 in the inner cylinder 10 of the sleeve of the example was the same as that of the third embodiment. On the other hand, the sleeve of the comparative example had the same size as the sleeve of the example, and the outer cylinder 20 was also made of S45C, and the inner cylinder 10 was entirely made of TC composite material. The TC composite material used for the sleeve of the example and the TC composite material used for the sleeve of the comparative example were obtained from the same raw material under the same conditions.

The sleeves of the examples and the sleeves of the comparative examples were placed in a state in which their axial directions were horizontal, and their front ends were communicated with the cavity of the same cold chamber die casting apparatus, and molten aluminum alloy (ADC 12) was supplied from the pouring hole. , and by advancing the plunger tip entered from the rear end, an operation was performed to fill the cavity with the molten aluminum alloy. At the rear end of the sleeve, a probe of a dial gauge was brought into contact with the upper end of the cylindrical portion, and changes in displacement with time from the time when the molten metal was supplied to the sleeve were measured. The amount of displacement was measured so that upward displacement was a positive value. The results are shown in FIG. 3(a).

From FIG. 3(a), it can be seen that the amount of upward warping of the rear end of the sleeve of the example is clearly suppressed as compared with the sleeve of the comparative example. FIG. 3B shows the ratio (percentage) of the amount of displacement of the sleeve of the example with respect to the amount of displacement of the sleeve of the comparative example. The time from the time the molten metal is supplied from the pouring hole to the time the cavity is completely filled (required time for one shot) is about 10 seconds. In the sleeve of the example, the displacement in the time required for one shot is suppressed to about one third of that of the sleeve of the comparative example.

As described above, the present invention has been described with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and as shown below, various improvements can be made without departing from the scope of the present invention. and design changes are possible.

For example, the inner peripheral surfaces of the upper wall portion 11 and the lower wall portion 12 constituting the inner cylinder 10 can be provided with a surface treatment layer by surface treatment such as nitriding treatment, carbonization treatment, and boride treatment.

In the above description, silicon carbide (SiC) was exemplified as a raw material of the TC composite material, but it is not limited to this, and nitride ceramics such as Si ₃ N ₄ , TiN, BN, and ALN, TiC, Carbide ceramics such as _B4C and _{CrC2 ,} boride ceramics such as _ZrB2 and _TiB2 , oxide ceramics such as _{Cr2O3 , TiO2} , _ZrO2 , MgO and _Y2O3 , and sialon can be used singly or in combination.

Further, when the sleeve is long, the inner cylinder may be divided into a rear end side including the pouring hole and a front end side to form a rear end side inner cylinder portion and a front end side inner cylinder portion. For example, the inner cylinder 10 of the length N portion on the front end side in the third embodiment is the front end inner cylinder portion, and the inner cylinder 10 of the length (LN) portion on the rear end side is the rear end inner cylinder. can be part of Alternatively, the entire front end side inner cylinder portion is made of the second material, and the rear end side inner cylinder portion has the same configuration as the inner cylinder 10 of either the first embodiment or the second embodiment. Alternatively, the boundary between the upper wall portion 11 and the lower wall portion 12 may be discontinuous at the boundary between the front end side inner cylinder portion and the rear end side inner cylinder portion. Even with these configurations, the same effects as described above are exhibited.

1 Sleeve (sleeve for die casting)
2 Sleeve (sleeve for die casting)
3 Sleeve (sleeve for die casting)
10 Inner cylinder 11 Upper wall part 12 Lower wall part 20 Outer cylinder 30 Pouring hole E1 Front end E2 Rear end UN Immediately below

Claims (3)

It has a cylindrical cylindrical portion and a pouring hole penetrating a part of the side peripheral wall of the cylindrical portion. A sleeve for die casting,
The cylindrical portion has a cylindrical outer cylinder and a cylindrical inner cylinder fitted into the outer cylinder,
The inner cylinder has an upper wall portion formed of a first material at least from the periphery of the pouring hole to the rear end, and has a second wall portion from at least directly below the pouring hole to the rear end. having a lower wall made of two materials,
The second material has a smaller coefficient of thermal expansion than the first material,
The height h of the boundary between the upper wall portion and the lower wall portion is 1/4 to 1/2 times the outer diameter R of the inner cylinder at the rear end, and the outer diameter R at the front end. and the height h increases linearly from the rear end to the front end
A die-casting sleeve characterized by: It has a cylindrical cylindrical portion and a pouring hole penetrating a part of the side peripheral wall of the cylindrical portion. A sleeve for die casting,
The cylindrical portion has a cylindrical outer cylinder and a cylindrical inner cylinder fitted into the outer cylinder,
The inner cylinder has an upper wall portion formed of a first material at least from the periphery of the pouring hole to the rear end, and has a second wall portion from at least directly below the pouring hole to the rear end. having a lower wall made of two materials,
The second material has a smaller coefficient of thermal expansion than the first material,
The height h of the boundary between the upper wall portion and the lower wall portion is 1/4 to 1/2 times the outer diameter R of the inner cylinder at the rear end, and the height h is the rear end to the front end side, and the height h coincides with the outer diameter R at a position where the length in the axial direction from the front end is N, and the height h coincides with the outer diameter R in the axial direction. When the total length of the inner cylinder is L, the maximum length (LN) of the upper wall portion is 3/2 to 3 times the length of the pouring hole in the axial direction. A die- casting sleeve characterized by The die-casting sleeve according to Claim 1 or Claim 2 , wherein the second material has a lower thermal conductivity than the first material .

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