JPH0679426A - Sleeve for injection molding of molten metal - Google Patents

Abstract

PURPOSE:To provide the sleeve having excellent structural strength even in a high-temp. state by constituting the sleeve of a triple structure consisting of an inside cylinder made of sialon ceramics or dense silicon nitride ceramics, an intermediate cylinder made of zirconia ceramics and an outside cylinder made of a heat resistant metal. CONSTITUTION:The 'sialon ceramics or dense silicon nitride ceramics' which is the material having excellent heat-wear resistance, corrosion resistance, thermal impact resistance, strength and wettability even at a high temp. is selected as the inside cylinder 1. The material 'zirconia ceramics' which has the excellent heat insulating characteristic and strength and has the coefft. of thermal expansion of value higher than the inside cylinder and lower than the value of the outside cylinder is selected as the intermediate cylinder 2. The outside cylinder 3 consists of the triple structure of the material 'heat resistant metal' which is easy in design of the construction and production. Further, a heater for heating is mounted in the inside part or outer peripheral part of the inside cylinder or the inside part, inner peripheral part or outer peripheral part of the intermediate cylinder. As a result, the sleeve is forcibly heated to an ideal temp. distribution and is applicable even to casting of a high material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melt injection molding sleeve, and in particular, (1) wear resistance, corrosion resistance, wettability, heat resistance, heat shock resistance, heat insulation,
Molten metal injection molding sleeve with excellent structural strength, and (2) In this injection molding sleeve, heating type injection molding of molten metal that can forcibly maintain the inner cylinder in contact with the molten metal in a high temperature range. For sleeves.

[0002]

2. Description of the Related Art In a molten metal injection molding sleeve, a plunger reciprocates in the sleeve in the axial direction at a high temperature to inject the molten metal at a high temperature, so that the inner surface of the sleeve is contacted with the molten metal. It is eroded and wears due to sliding with the plunger. Further, due to the above-mentioned erosion and wear, the surface quality of the inner surface of the sleeve is deteriorated and the clearance with the plunger tip is increased, so that the adhesion of the molten metal occurs, which adversely affects the casting operation and the casting.

Conventionally, in order to prevent damage to the inner surface of the sleeve due to the above erosion and wear, for example, a hot die steel such as SKD-61 is used for the injection molding sleeve. However, hot die steel has poor heat insulation due to its high thermal conductivity, and also has a large temperature dependence of hardness and strength,
Since these mechanical property values are remarkably deteriorated at high temperatures, they have the drawback of being inferior in hot wear resistance.

In order to compensate for the above-mentioned inferiority in terms of material, an injection molding sleeve having a structure in which the sleeve is water-cooled is used. However, since the temperature of the inner surface of the sleeve is inevitably lowered by water-cooling, a part of the molten metal is Since the solidified phase is easily solidified inside and the broken fragments of the solidified phase are mixed inside the casting, insufficient strength and variations occur in the quality of the casting. Therefore, in order to prevent the temperature of the molten metal from lowering due to contact with the low-temperature sleeve, casting is carried out by a method in which hot molten metal is supplied in advance. It becomes shorter and the temperature of the molten metal is raised, which is not preferable in terms of quality and energy saving.

In order to solve the above-mentioned problems with the hot die steel sleeve, a material having excellent wear resistance, corrosion resistance, heat resistance, thermal shock resistance, heat insulation and wettability is used. A double-structured injection molding sleeve including a cylinder and an outer cylinder made of heat-resistant metal has been proposed. For example, there has been proposed a double-structured injection molding sleeve having an inner cylinder made of dense silicon nitride ceramics and the like and an outer cylinder made of heat-resistant metal (see Japanese Patent Laid-Open No. 53-70034).

In this double-structured injection molding sleeve,
Although it has excellent wear resistance, corrosion resistance, heat resistance, thermal shock resistance, and wettability, dense silicon nitride ceramics has a relatively high thermal conductivity, so the heat insulating effect is insufficient, and the temperature of the outer cylinder during casting is low. Has the disadvantage that the temperature of the molten metal decreases in the sleeve.

Furthermore, since the dense silicon nitride ceramics have a small coefficient of thermal expansion, while the outer cylinder made of heat-resistant metal has a large coefficient of thermal expansion, the thermal expansion amount between the inner cylinder and the outer cylinder becomes high when the entire sleeve has a high temperature. Difference becomes large in both the axial direction and the radial direction of the sleeve, and the inner cylinder cannot be accurately restrained in the outer cylinder, so that the relative positional accuracy and attitude accuracy of the inner cylinder and the outer cylinder deteriorate. For this reason, the relative positional accuracy and posture accuracy of the reciprocating shaft of the plunger and the shaft of the inner cylinder are deteriorated, the sliding state between the inner surface of the sleeve and the plunger tip is deteriorated, and wear is increased, or Because of uneven wear,
The life of the sleeve is shortened.

In order to avoid this, a triple-structured injection molding sleeve has been proposed in which an intermediate cylinder made of a material having excellent heat insulating properties is incorporated between an inner cylinder and an outer cylinder.
For example, there has been proposed an injection molding sleeve having a triple structure including an inner cylinder made of dense silicon nitride ceramics, an intermediate cylinder made of porous silicon nitride ceramics, and an outer cylinder made of heat-resistant metal (Japanese Patent Laid-Open No. 2- (See Japanese Patent No. 104459). This triple-structured injection molding sleeve has excellent wear resistance, corrosion resistance, heat resistance, thermal shock resistance and wettability, as well as the double structure injection molding sleeve. It has the advantages that the temperature of the molten metal in the sleeve is small and that the temperature of the outer cylinder can be made relatively low.

[0009]

However, in the above-mentioned triple-structured injection molding sleeve, the porous silicon nitride ceramics used as the intermediate cylinder does not have a sufficient heat insulating effect, and the inner cylinder is heated to a sufficiently high temperature. Since it cannot be maintained, the temperature of the molten metal in the sleeve decreases, which is disadvantageous in terms of the quality of the casting. Further, the coefficient of thermal expansion of this porous silicon nitride ceramics is as small as that of the dense silicon nitride ceramics, while the coefficient of thermal expansion of the outer cylinder made of heat-resistant metal is large, so that it cannot be used at high temperature during casting. The difference in the amount of thermal expansion between the intermediate cylinder made of porous silicon nitride ceramics and the outer cylinder made of heat-resistant metal becomes large in both the axial direction and the radial direction of the sleeve, and the intermediate cylinder can be accurately restrained in the outer cylinder. Defects such as disappearance occur.

Further, since the porous silicon nitride ceramics is weak in strength and the tightening margin due to shrink fitting cannot be increased, a sufficient force for accurately restraining the intermediate cylinder and the inner cylinder in the outer cylinder is obtained. It is difficult to do so, and it is difficult to maintain the relative positional accuracy and attitude accuracy of the intermediate cylinder and the inner cylinder and the outer cylinder. For this reason, the relative positional accuracy and attitude accuracy between the shaft of the plunger and the shaft of the inner cylinder deteriorates, the sliding state between the inner surface of the sleeve and the plunger tip deteriorates, and wear increases, Due to uneven wear, the service life of the sleeve is shortened.

In order to solve such a problem, a method has been adopted in which the inner cylinder and the intermediate cylinder are previously joined and then the outer cylinder is joined by shrink fitting or the like. However, in such a method, since the difference in the coefficient of thermal expansion between the intermediate cylinder and the outer cylinder is large, it is necessary to increase the shrink fitting allowance between the intermediate cylinder and the outer cylinder. It becomes a problem. Also, the temperature of the outer cylinder must be set to a relatively high temperature during shrink fitting, which is clearly disadvantageous in design and manufacturing.

Further, in the above conventional triple-structured injection molding sleeve (similarly to the above-mentioned conventional double-structured injection molding sleeve), the temperature distribution inside the sleeve is such that the molten metal in the injection hole is Strongly affected by the distribution state of. Particularly in a sleeve used for a horizontal die-casting machine, the molten metal supplied in the casting process is injected into the mold along the bottom of the injection hole of the sleeve, so the temperature distribution inside the sleeve is lower than the upper temperature. The amount of thermal expansion of the lower part is larger than that of the upper part, so that the entire sleeve is warped.

Since such a warp is caused by uneven temperature distribution, the double structure injection molding sleeve having a small heat insulating effect is more remarkable than the triple structure injection molding sleeve having a large heat insulating effect. Appear in. Furthermore, as a matter of course, the higher the melting point of the metal material to be cast, the higher the temperature of the molten metal and the higher the temperature inside the sleeve, so that the above-mentioned problems become conspicuous. Therefore, it is very difficult to apply the above-mentioned conventional injection molding sleeve to the casting of a metal material having a higher melting point.

An object of the present invention is to provide a molten metal injection molding sleeve which solves the above-mentioned drawbacks and problems of the conventional injection molding sleeve. In detail, one of the objects of the present invention is (1) excellent in wear resistance, corrosion resistance, wettability, heat resistance, thermal shock resistance, and heat insulating property with respect to high-temperature molten metal materials, and (2) Even when the sleeve is hot during casting, the positional accuracy and posture accuracy between the axis of the plunger movement and the axis of the sleeve inner surface are sufficiently good.
(3) In addition, it has excellent wear resistance against sliding between the plunger tip and the inner surface of the sleeve. (4) Therefore, the service life is long, and (5) High temperature insulation and heat retention keeps the temperature of the molten metal low. Which is advantageous from the viewpoint of energy saving, and (6) can improve the quality of cast products, and (7) can be applied to a metal material with a high melting point. To provide.

The second object of the present invention is to provide the above (1) to (5).
In addition to (8), it is possible to forcibly control the inside of the sleeve in a relatively high temperature range.
(9) A heat-injection molding sleeve for die casting, which can obtain a highly reliable cast metal that is more structurally and strength stable, and (10) can be applied to a metal material having a higher melting point. There is.

[0016]

The present invention is an invention (hereinafter referred to as a first invention) that solves the problems (1) to (7), which are "one of the objects of the present invention", and the "present invention. The invention (hereinafter, referred to as a second invention) for solving the above-mentioned problems (1) to (5) and (8) to (10), which is the second object of the invention.

The first invention has a triple structure of an inner cylinder, an intermediate cylinder and an outer cylinder. (A) The inner cylinder has wear resistance, corrosion resistance, heat resistance, thermal shock resistance, heat insulation, strength and strength even at high temperatures. A ceramic material with excellent wettability is used. (B) The intermediate cylinder has excellent heat insulation and strength, and has a coefficient of thermal expansion larger than that of the inner cylinder and smaller than that of the outer cylinder. It is characterized by the use of a ceramics material having the characteristics that are the values, and (C) the use of an inexpensive metal material that is easy to structurally design and manufacture as the outer cylinder, which results in the above (1) to (7). It is a solution to the problem.

That is, the first invention is for molten metal injection molding characterized by having a triple structure of an inner cylinder made of sialon ceramics or a dense silicon nitride ceramics, an intermediate cylinder made of zirconia ceramics and an outer cylinder made of heat-resistant metal. Sleeve. "

The second invention is the same as the first invention.
The inner cylinder of (A), the intermediate cylinder of (B) and the outer cylinder of (C) have a triple structure.In addition, (D) the inner cylinder is forcibly temperature controlled in a relatively high temperature range. Is characterized in that a heating heater is attached to the inside or the outer peripheral portion or the inside of the intermediate cylinder, or the inner peripheral portion or the outer peripheral portion, and thereby, the problems (1) to (5) and (8) to (10) are solved. It has been resolved.

That is, the second aspect of the present invention is "a triple structure of an inner cylinder made of sialon ceramics or a dense silicon nitride ceramics, an intermediate cylinder made of zirconia ceramics, and an outer cylinder made of heat-resistant metal. A sleeve for molten metal injection molding, characterized in that a heater is attached to the inside, the inner peripheral portion, or the outer peripheral portion of the intermediate cylinder. "

The present invention will be described in detail below in terms of materials and structures based on drawings and tables. In the following description, the expression “present invention” is used to include both the first invention and the second invention, unless otherwise specified.

FIG. 1 is a schematic cross-sectional view showing an integrated structure of an injection molding sleeve for die casting which is an embodiment of the first invention, and has a triple structure of an inner cylinder 1, an intermediate cylinder 2 and an outer cylinder 3. Consists of. In FIG. 1, 4 is a plunger tip, 5 is
Is a mounting plate (a mounting plate for axially fixing the inner cylinder 1 and the intermediate cylinder 2), and 6 is a hot water supply port. Further, FIG. 2 is a schematic view showing an integrated structure of a heating type injection molding sleeve for die casting which is an embodiment of the second invention.
(A) is a sectional view taken along line BB of (B), and (B) is a sectional view taken along line AA of (A). This has a triple structure of an inner cylinder 1, an intermediate cylinder 2 and an outer cylinder 3 as in the first invention, but further includes a heating heater-7.
It is different in that it is attached.

First, the function of the material surface of each cylinder in the present invention will be described. The inner surface of the inner cylinder 1 is in contact with the high temperature molten metal during casting (the inner cylinder 1 in FIG. 2 is further heated by the heater 7 and is in a high temperature state),
Moreover, the plunger tip 4 and its inner surface slide.
For this reason, the inner cylinder 1 is required to be a material having excellent properties in wear resistance, corrosion resistance, heat resistance, thermal shock resistance, heat insulation, strength, and wettability even at high temperatures. Sialon ceramics and dense silicon nitride ceramics are well suited to this requirement. The suitability of the ceramic will be described below for each characteristic.

(Abrasion resistance) The abrasion resistance of sialon ceramics and dense silicon nitride ceramics at high temperature is 1500-1650H at room temperature (Vickers hardness).
It is about v, and even at 1000 ° C., it drops only to about 800 to 1300 Hv. On the other hand, in the case of SKD-61, the temperature is about 520 Hv at room temperature, and it drops remarkably as the temperature rises.

FIG. 5 shows an example of this, and is a characteristic diagram showing changes in Vickers hardness with temperature changes of sialon ceramics, dense silicon nitride ceramics, and SKD-61. The curves in the figure are for Sialon ceramics, the curves are for dense silicon nitride ceramics, and the curves are for SKD-61.

The longitudinal elastic modulus of sialon ceramics and dense silicon nitride ceramics is about 280 to 300 GPa at room temperature. Although it decreases as the temperature rises, it hardly decreases up to about 800 ° C, and it is about 220 to 260 GPa even at 1000 ° C, which has excellent characteristics equal to or higher than the value of the refractory metal at room temperature.

FIG. 6 shows an example of this, and is a characteristic diagram showing changes in longitudinal elastic modulus of sialon ceramics and dense silicon nitride ceramics with temperature changes. The curve in the figure is for sialon ceramics, and the curve is for dense silicon nitride ceramics.

In order to compare the "wear characteristics due to sliding" between the sialon ceramics and the dense silicon nitride ceramics and the refractory metal, the inventors of the present invention compare them with the sialon ceramics, the dense silicon nitride ceramics,
Regarding hot die steel, a slurry of SiC abrasive grains was supplied as a polishing agent and slid on a disk-shaped sample of the same size on a lapping machine with a load of 10 kg applied, and the thickness with sliding time The amount of wear loss in the direction was measured.

FIG. 7 shows the results of this test and is a characteristic diagram showing changes in the thickness loss of the sample with sliding time of the sialon ceramics, the dense silicon nitride ceramics and the hot die steel. The curves in the figure are for Sialon ceramics, the curves are for dense silicon nitride ceramics, and the curves are for SKD-61.

Also in this test result, the sialon ceramics and the dense silicon nitride ceramics showed excellent characteristics. From the above, it was confirmed that the sialon ceramics and the dense silicon nitride ceramics exhibited the characteristics of being superior in wear resistance to the hot die steel even at high temperatures, and were suitable for the material of the inner cylinder of the present invention. .

(Corrosion Resistance) Corrosion resistance of sialon ceramics and dense silicon nitride ceramics to high temperature molten metal will be described. Table 1 is shown as an example of the corrosion resistance test of sialon ceramics and dense silicon nitride ceramics against high temperature molten metal. Table 1 shows that a sample of sialon ceramics was dipped in a molten metal of pure aluminum and four kinds of aluminum alloys, the sample was washed with an aqueous solution of sodium hydroxide, and the dry weight before and after the immersion was measured to determine the change in weight. The results of the immersion test examined are displayed.

[0032]

[Table 1]

The inventors of the present invention also conducted the same test for other molten metals such as zinc alloy and magnesium alloy, and obtained the result that "the weight change before and after the immersion is almost zero". From Table 1 and these test results, it was confirmed that the sialon ceramics and the dense silicon nitride ceramics are hardly corroded by the molten metal at high temperature and are suitable for the material of the inner cylinder of the present invention.

(Leakage) Leakage of sialon ceramics and dense silicon nitride ceramics with respect to high-temperature molten metal will be described. The inventors of the present invention have conducted a number of tests on leak resistance of sialon ceramics and dense silicon nitride ceramics to molten metals such as high-temperature aluminum alloys, zinc alloys and magnesium alloys, and found that sialon ceramics and dense silicon nitride ceramics It was confirmed that the material is suitable for the material of the inner cylinder of the present invention, because it hardly leaks to the molten metal and exhibits extremely good characteristics.

(Regarding Thermal Shock Resistance) Next, the thermal shock resistance will be described. The present inventors tested the thermal shock resistance of sialon ceramics and dense silicon nitride ceramics by the following two methods.

As a first method, a thermal shock resistance test against quenching was conducted under the condition that the whole sample was kept at a uniform temperature. The test method is as follows. First, the sialon ceramics and the dense silicon nitride ceramics samples were heated and kept at the test temperature in an air atmosphere furnace, and the entire sample was kept at a uniform temperature. Next, immediately after taking out from the furnace, it is water-cooled, its flexural strength is measured based on JIS R1601, and it is investigated whether or not the strength is reduced due to the occurrence of cracks due to thermal shock, and the test temperature when the strength is reduced In this method, the difference between the temperature of water used for water cooling and the temperature of water used for water cooling is used as the thermal shock resistance (ΔT). According to the result of this test, the thermal shock resistance value (Δ) of sialon ceramics and dense silicon nitride ceramics
T) was about 600 to 650 ° C.

As a second method, a thermal shock resistance test was carried out when a part of the sample was rapidly heated and rapidly cooled. The test method is as follows. By measuring the AE wave during rapid heating and quenching, investigate whether there is an abnormal wave that occurs when a crack occurs in the sample, and then use a flaw detector after the sample temperature after quenching has dropped to room temperature. A test was conducted to check whether or not cracks were generated on the sample surface.

The contents of this test are as follows: (1) First, in order to examine the thermal shock resistance due to rapid heating, 740 to 900 ° C., using cylindrical sialon ceramics and dense silicon nitride ceramics samples with dimensions of φ70 × 40t. A part of the sample up to 2 mm from the end face was immersed for 30 seconds in the molten aluminum at a high temperature while measuring the AE wave. (2) Next, in order to examine the thermal shock resistance by rapid cooling, it was rapidly heated by the above method. The portion is immersed in water while measuring the AE wave, rapidly cooled for 30 seconds, and then, after the temperature of the sample has dropped to room temperature, the presence or absence of cracks on the surface portion of the sample is examined by a flaw detection agent.

The second test method is a method of confirming an abnormal wave generated when a crack is generated in a sample by measuring an AE wave, and water cooling when a crack is confirmed by a visual inspection with a flaw detection agent. In this method, the temperature difference between the temperature of the previous test part and the water temperature is used as the thermal shock resistance value (ΔT). According to the results of this test, regarding the thermal shock resistance due to rapid heating, no abnormal AE wave was observed during rapid heating, and sialon ceramics and dense silicon nitride ceramics showed 740-9.
No cracks were generated by the rapid heat generated by the molten aluminum at about 00 ° C.

Further, in the test of only rapid heating, a crack inspection was not observed when a flaw inspection was conducted after the sample was gradually cooled after rapid heating. Also, thermal shock resistance value (△
T) was about 370 to 420 ° C. From the above test results,
Sialon ceramics and dense silicon nitride ceramics exhibit excellent thermal shock resistance against local rapid heat due to the high-temperature molten metal required for the material of the inner cylinder of the present invention, and are also rapidly cooled under actual use conditions. It has been confirmed that it is suitable for the material of the inner cylinder of the present invention.

(Adiabatic Property) Next, the adiabatic property will be described. Table 2 shows various characteristics of various ceramic materials and heat-resistant metal materials used for injection molding sleeves for die casting at room temperature. As shown in Table 2, the thermal conductivity of sialon ceramics and dense silicon nitride ceramics is about 14 to 18 kcal / m · h · ° C, and SKD-61
Has a thermal conductivity of about 26 kcal / m ・ h ・ ° C. Therefore, sialon ceramics and dense silicon nitride ceramics are
It has excellent heat insulating properties as compared with D-61 and is suitable for the material of the inner cylinder of the present invention.

[0042]

[Table 2]

(Strength) Next, strength will be described. The bending strength of sialon ceramics and dense silicon nitride ceramics is about 800 to 1000MPa at room temperature, which decreases with increasing temperature, but does not decrease to about 800 ° C and is about 700 to 900MPa even at 1000 ° C. . Further, as described above, the longitudinal elastic modulus is also a relatively high value at room temperature, and it decreases with increasing temperature, but hardly decreases up to about 800 ° C (see Fig. 6). Strength is sufficient and deformation is relatively small.

As an example of this, FIG. 8 is shown. FIG. 8 shows sialon ceramics, dense silicon nitride ceramics,
FIG. 4 is a characteristic diagram showing changes in flexural strength of MgO-stabilized zirconia ceramics, Y ₂ O ₃ -stabilized zirconia ceramics, and porous silicon nitride ceramics with temperature changes.
The curve in FIG. 6 is for sialon ceramics, the curve is for dense silicon nitride ceramics, the curve is for MgO-stabilized zirconia ceramics, the curve is for Y ₂ O ₃ -stabilized zirconia ceramics, and the curve is for porous silicon nitride ceramics. Sialon ceramics and dense silicon nitride ceramics are excellent in strength at high temperatures as seen from FIG. 8, and are suitable for the material of the inner cylinder of the present invention.

The sialon ceramics and the dense silicon nitride ceramics having the above characteristics are used as the material of the inner cylinder of the injection molding sleeve for die casting and the heating injection molding sleeve for die casting of the second invention. ,
It can be seen that it fits very well.

Next, the material of the intermediate cylinder in the present invention will be described. The purpose of providing the intermediate cylinder 2 in FIG. 1 (the intermediate cylinder 2 in the first aspect of the invention) is to keep the inner cylinder 1 at a high temperature and at the same time the outer cylinder 3 at a relatively low temperature so that the inside of the sleeve can be maintained. This is to reduce the thermal loss of the molten metal and maintain the relative positional accuracy and attitude accuracy of the inner cylinder 1 and the outer cylinder 3 even during casting.

Further, for the purpose of providing the intermediate cylinder 2 (intermediate cylinder 2 in the second aspect of the invention) in FIG. 2, the inner cylinder 1 is formed by the combined use of the heating by the heating heater 7 and the heat insulating effect of the intermediate cylinder 2. By maintaining the outer cylinder 3 at a relatively low temperature while maintaining a high temperature at a relatively low running cost and at the same time the inner cylinder 1 becomes a high temperature, the thermal conductivity of the molten metal in the sleeve is the same as above. Inner cylinder 1 with less loss and during casting
This is to maintain the relative positional accuracy and attitude accuracy between the outer cylinder 3 and the outer cylinder 3. Therefore, the intermediate cylinder 2 in the present invention must be a material having excellent heat insulating properties.

Further, in the temperature distribution of each cylinder during casting in the triple structure injection molding sleeve of the present invention, the inner cylinder 1 has the highest temperature, and the intermediate cylinder 2 and the outer cylinder 3 have lower temperatures in this order. ,
In order to maintain the relative position accuracy and attitude accuracy described above, the difference in the amount of thermal expansion of the fitting portion between the cylinders should not be adversely affected by the sliding state between the sleeve inner surface and the plunger tip. Must be small. Therefore, the intermediate cylinder 2
Coefficient of thermal expansion is larger than the coefficient of thermal expansion of the inner cylinder 1 and smaller than the coefficient of thermal expansion of the outer cylinder 3, and the contact stress due to joining such as shrinkage fitting is required. It is desirable that the material has a strength capable of withstanding. The various properties of zirconia-based ceramics are well suited to these conditions. The suitability of this ceramic will be described below for each characteristic.

(Adiabatic Property) First, the adiabatic property will be described. The thermal conductivity of zirconia-based ceramics is 1.
8 to 3.3 kcal / m · h · ° C, which is a low value compared with heat-resistant steel, silicon nitride, sialon, and of course, porous silicon nitride ceramics (see Table 2 above), and has excellent heat insulation properties. Is suitable for the material of the intermediate cylinder of the present invention.

(Regarding Thermal Expansion Coefficient) Next, the thermal expansion coefficient will be described. The thermal expansion coefficient of zirconia-based ceramics is about 7.0 to 10.5 × 10 ^-6 / ° C, whereas the thermal expansion coefficient of sialon ceramics and dense silicon nitride ceramics, which are the materials of the inner cylinder, is 3.0 to 3.4 × 10. ^-6
On the other hand, the thermal expansion coefficient of the refractory metal that is the material of the outer cylinder is about 11 to 12 × 10 ⁻⁶ / ° C. (see Table 2 above). Therefore, the zirconia-based ceramics have the characteristics that satisfy the above-mentioned conditions for the coefficient of thermal expansion of the intermediate cylinder.

(Regarding Strength) Next, strength will be described. The bending strength of zirconia-based ceramics is, for example, 400M at room temperature in the case of MgO-stabilized zirconia ceramics.
It is about Pa, and it decreases as the temperature rises, but 300
Almost no decrease up to about 0 ° C. and about 250 MPa even at 1000 ° C. (see FIG. 8). With Y ₂ O ₃ -stabilized zirconia ceramics, the temperature is about 1200 MPa at room temperature, which decreases as the temperature rises, but does not decrease to about 300 ° C., and even at 1200 ° C. is about 350 MPa (see FIG. 8).
reference).

On the other hand, in the case of porous silicon nitride ceramics, the bending strength hardly changes with temperature, but it is as low as about 200 MPa (see FIG. 8). For this reason, when porous silicon nitride ceramics is used for the intermediate cylinder, the heat insulation is not sufficient, and due to insufficient strength, it is difficult to join the outer cylinder by shrink fitting or the like. When it is used for a cylinder, it has excellent heat insulation properties and can lower the temperature of the boundary surface between the intermediate cylinder and the outer cylinder during casting, so that the interference such as shrinkage fitting may be small. Therefore, the contact stress due to joining such as shrink fitting is small, and the strength is relatively strong, so there is no strength problem regarding joining, and joining such as shrink fitting with the outer cylinder is easy.

From the above, zirconia-based ceramics have characteristics suitable as the material of the intermediate cylinder of the present invention. In particular, MgO-stabilized zirconia ceramics has excellent heat insulating properties, and the coefficient of thermal expansion is approximately intermediate between that of the sialon ceramics and dense silicon nitride ceramics of the inner cylinder and the refractory metal of the outer cylinder (see Table 2 above). ), It is very suitable as a material for the intermediate cylinder.

Next, the material of the outer cylinder of the present invention will be described. The injection molding sleeve for die casting of the present invention,
A die casting machine is used by the outer cylinder 3 in FIGS. 1 and 2.
It is attached to the main body. Therefore, as the outer cylinder 3,
It is required that the position accuracy and the attitude accuracy of the moving shaft of the plunger of the die-casting machine and the shaft of the inner surface of the sleeve can be maintained in a good state, and the handling in the casting work is easy.

Further, although the heat from the inner surface of the sleeve is considerably insulated by the heat insulating effect of the intermediate cylinder 2, it must be excellent in heat resistance because it is also received from the mold and the die casting machine. . Therefore, the outer cylinder 3 is a material that has high strength, has a certain degree of heat resistance, is easy to handle in casting work, and is easy to mount and adjust on the die-cast machine body. Required. From the above, a heat resistant metal such as SKD-61 is suitable as the material of the outer cylinder 3.

Next, the function of the structural surface of the injection molding sleeve for die casting according to the present invention will be described. In injection-molded sleeves for die-casting, the clearance between the cylinders is determined by the position between the axis of movement of the plunger and the axis of the inner surface of the sleeve even when the sleeve during casting has a high temperature during casting. It is required that the accuracy and the posture accuracy are sufficiently good and that the sliding state between the plunger tip and the inner surface of the sleeve is not adversely affected. For that purpose, it is an effective means to reduce the difference in the thermal expansion amount of the fitting portion between the respective cylinders inside the sleeve, whichever joining method is used.

As described above, in the injection molding sleeve for die casting of the present invention, the inner cylinder 1 is made of sialon ceramics or dense silicon nitride ceramics, the intermediate cylinder 2 is made of zirconia ceramics, and the outer cylinder 3 Is made of heat-resistant metal. The temperature distribution inside the sleeve is highest in the inner cylinder 1 and lower in the order of the intermediate cylinder 2 and the outer cylinder 3. Further, since the inner cylinder 1 and the intermediate cylinder 2 are made of a material having a low thermal conductivity, The temperature of the cylinder 3 is low.

Regarding the coefficient of thermal expansion, the inner cylinder 1 is the smallest and the intermediate cylinder 2 and the outer cylinder 3 are larger in this order. Further, as a matter of course, in the present invention, by adjusting the wall thickness of each cylinder (in the second invention, in addition to the adjustment of the wall thickness of each cylinder, the mounting position of the heating heater 7 and The temperature of each cylinder and the temperature of the boundary between the cylinders can be adjusted by adjusting the amount of heat generation. Utilizing this feature, the present invention can reduce the difference in the thermal expansion amount of the fitting portion between the cylinders.

Therefore, in the present invention, it is possible to join the cylinders not only by shrink fitting, but also by press fitting, clearance fitting, or cast molding. Further, even in the case of shrink fitting, since the outer cylinder 3 is at a relatively low temperature during casting, sufficient accuracy can be obtained during casting even if the shrink fitting margin is small. Further, since the intermediate cylinder 2 is made of zirconia ceramics, the outer cylinder 3
There is no problem in strength regarding shrink-fitting joint with.

Particularly, in the heating type injection molding sleeve for die casting of the second invention, the heating heater 7 (see FIG. 2) mounted in the sleeve forces the temperature distribution in the sleeve. Since it is possible to control the temperature in a relatively high temperature range, the temperature distribution in the sleeve is controlled to be almost uniform by considering the influence of the molten metal distribution in the injection holes. The advantage is that the amount of thermal expansion can be balanced during casting, and the warpage is extremely small.

As described above in detail, the present invention (the injection molding sleeve for die casting of the first invention and the heating injection molding sleeve for die casting of the second invention) is made of sialon ceramic or dense silicon nitride ceramic (internal (Cylinder), zirconia-based ceramics (intermediate cylinder), and heat-resistant metal (outer cylinder) are combined, and are excellent from the material side of each cylinder,
It is also excellent in terms of structure and manufacturing.

[0062]

EXAMPLES Next, the present invention will be described in more detail with reference to examples of the present invention. Examples 1 to 3 below are examples of the first invention, and Examples 4 to 6 are examples of the second invention.

(Embodiment 1-First Invention) The first embodiment of the first invention will be described with reference to FIG. This Example 1
As shown in FIG. 1, consists of an inner cylinder 1, an intermediate cylinder 2 and an outer cylinder 3. The inner cylinder 1 is made of integral sialon ceramics, and the intermediate cylinder 2 is also made of integral MgO-stabilized zirconia ceramics. The outer cylinder 3 is made of SKD-61. The dimensions of the main part of each cylinder are the values shown in Table 3.

[0064]

[Table 3]

The inner cylinder 1 and the intermediate cylinder 2 are joined with a clearance fit, and the intermediate cylinder 2 and the outer cylinder 3 are joined with each other by shrink fitting to produce an injection molding sleeve having the structure shown in FIG. Machine
It was mounted on the test piece and subjected to a practical use test of 100,000 shots under the casting conditions shown in Table 4.

[0066]

[Table 4]

After the use, the inner surface of the sleeve was observed, the amount of wear loss was measured, the internal temperature of the inner cylinder during casting, and the temperature of the boundary between the cylinders were measured. In FIG. 1, (1) to (3) are temperature measurement points. ...... Temperature measurement point inside the inner cylinder ...... Temperature measurement point at the boundary between the inner cylinder 1 and the intermediate cylinder ...... Temperature measurement point at the boundary between the intermediate cylinder 2 and the outer cylinder 3

Further, using the temperature measurement results, the clearance between each cylinder and the shrink fitting margin during casting were simply calculated, and the heat insulating effect was confirmed. During this test, the operation of the plunger was always stable, and the observation of the inner peripheral surface of the sleeve inner cylinder after the test showed no evidence of uneven wear and erosion. Further, when the inner diameters of the inner cylinder 1 before and after the test were compared, the wear amount due to 100,000 shot casting, that is, the increase amount of the inner diameter was only 0.014 mm.

From the above observation and measurement results, the plunger
It is considered that the sliding condition between the tip 5 and the inner surface of the sleeve was extremely good and there was almost no erosion by the molten metal.
Table 5 shows the temperature measurement results during steady casting, and Table 6 shows the simplified calculation results of the clearance between the cylinders during steady casting.

[0070]

[Table 5]

[0071]

[Table 6]

From this temperature measurement result, the inner cylinder 1 sufficiently satisfied wear resistance, corrosion resistance, wettability and strength even during casting,
Further, it was confirmed that the intermediate cylinder 2 was in a temperature range where the strength was sufficiently satisfied, and the heat insulating effect was sufficient. It was confirmed that due to this heat insulating effect, the outer cylinder 3 made of SKD-61 is less affected by the temperature of the molten metal and can be cast even at a relatively low superheat degree.

FIG. 9 shows the temperature change of the inner cylinder due to the difference in structure and each material. In the figure, the SKD-61 metal sleeve is used for the inner cylinder, and the SIARON ceramic sleeve is used for the inner cylinder, both of which are shown in the position of FIG. It is a figure showing the temperature change situation inside the lower part. (Note that FIG. 9 shows the temperature change situation in the case where the heating type Sialon ceramic sleeve is used for the inner cylinder, which corresponds to the example of the second invention described later.) From the viewpoint of 9, it was confirmed that in the case of the sialon sleeve of the first invention, preheating at a temperature of 100 ° C. or higher is possible as compared with the metal sleeve that remarkably radiates heat.

Furthermore, the time required for the temperature of the sleeve to reach a steady state after the start of casting can be shortened to about one-half time, and the steady temperature is 100 ° C. higher. It was also confirmed that the temperature change in the injection cycle was 5-8 ° C, which was significantly smaller than that of the metal sleeve at 50 ° C. Therefore, the sialon sleeve of the first invention is an effective means for obtaining stable casting conditions.

Further, in view of the difference in the amount of thermal expansion from the calculation results of the clearances between the cylinders and the shrinkage fitting allowance during steady casting (see Table 6 above), the axis of movement of the plunger of the die casting machine and the sleeve -Position accuracy and posture accuracy with respect to the axis of the inner surface of the sleeve were within a range that could be maintained in a good state. Therefore, it is considered that there was no uneven wear on the inner circumference of the inner cylinder.

The internal structure of the casting was observed. The micrograph is shown in FIG. 10 (A) -Photo 1. Due to the excellent heat retaining effect of the ceramic sleeve in Example 1, as shown in FIG. 10 (A) -Photo 1, a stable structure in which fine primary crystal aluminum and eutectic structure are uniformly dispersed. In addition, there is little mixing of coarse primary aluminum or fractured chill layer, which is considered to have been caused by the temperature drop of the molten metal in the ceramic strips or sleeves that cause hard spots, and good casting is possible. I confirmed that there is. 10 (B) -Photo 2 and FIG. 10 (C) -Photo 3 show the internal structure of a product cast by Comparative Example 1 (conventional injection-molding sleeve for die-casting) described below.
The two-layer structure in which the crystallized area ratio of i is discontinuously changed (Photo 2) and the coarse primary crystal aluminum dendrite structure (Photo 3) are shown.

(Embodiment 2-First Invention) The dimensions, structure, etc. of the main parts of each cylinder are the same as in Embodiment 1, but in this Embodiment 2, the material of the inner cylinder 1 is changed to Sialon ceramics. This is different from Example 1 in that a dense silicon nitride ceramics is used. As in Example 1, the inner cylinder 1 is made of one-piece dense silicon nitride ceramics, the intermediate cylinder 2 is made of one-piece MgO-stabilized zirconia ceramics, and the outer cylinder 3 is
An injection molding sleeve made of SKD-61 was prepared and mounted on the same die casting machine as in Example 1, under the same casting conditions.
After 100,000 shots of actual use test, after use,
The inner surface of the cast was observed and the wear loss was measured, and the internal structure of the casting was observed.

As a result of this test, in the observation of the inner peripheral surface of the sleeve inner cylinder, no evidence of uneven wear or erosion was confirmed, and the sleeve was
The amount of wear loss on the inner surface of the sleeve was 0.015 mm, and like the first embodiment, a peeling piece of ceramics that causes a hard spot in the internal structure of the casting or a fractured chill layer that seems to have occurred in the sleeve. No contamination was observed. From these things, the clearance between the cylinders at the time of casting is
Similar to the above, the position accuracy and posture accuracy between the moving shaft of the plunger of the die casting machine and the shaft of the inner surface of the sleeve can be maintained in a good state, and the sliding state between the plunger tip and the inner surface of the sleeve was considered to be extremely good. To be

Further, it has been confirmed that the heat loss of the molten metal in the injection hole of the sleeve is small due to the heat insulating / heat retaining effect, so that casting can be performed even at a superheat degree relatively lower than the melting point of the molten metal. From the above, it was confirmed that the same effect as in the case of the sialon ceramic of Example 1 can be obtained also in the dense silicon nitride ceramics.

(Embodiment 3-First Invention) FIG. 3 is a view for explaining another embodiment (third embodiment) of the first invention, which is a split mold of an injection molding sleeve for die casting. It is a typical sectional view showing a structure. The material and the size of the main part of each cylinder are the same as in Example 1, but the inner cylinder and the intermediate cylinder are each divided into five parts, and an injection molding sleeve having the structure shown in FIG. It was mounted on the same die-casting machine as above, and under the same casting conditions, 100,000 shots of the actual use test were conducted, the inner surface of the sleeve after use was observed and the wear loss amount was measured, and the internal structure of the casting was observed.

As a result of this test, in the observation of the inner peripheral surface of the sleeve inner cylinder, no evidence of uneven wear and erosion was confirmed, and the wear loss amount of the inner surface of the sleeve was 0.015 mm, which was the same as in Example 1. It was not observed that the peeled pieces of ceramics causing the hard spots in the internal structure or the inclusion of the fractured chill layer which seems to have occurred in the sleeve were observed. From these things, the clearance between the cylinders at the time of casting is
Similarly, the position accuracy and attitude accuracy of the moving shaft of the plunger of the die casting machine and the shaft of the inner surface of the sleeve can be maintained in a good state, and the sliding state between the plunger tip and the inner surface of the sleeve was extremely good. Conceivable.

Further, it has been confirmed that the heat loss of the molten metal in the injection hole of the sleeve is small due to the heat insulating / heat retaining effect, so that casting can be performed even at a superheat degree relatively lower than the melting point of the molten metal. From the above, it was confirmed that even in the split type structure, an action equivalent to that of the integrated type structure of Example 1 was obtained.

(Fourth Embodiment) A second embodiment of the second invention (Embodiment 4) will be described with reference to FIG. As shown in FIG. 2, this Embodiment 4 is composed of an inner cylinder 1, an intermediate cylinder 2, an outer cylinder 3 and a heating heater 7. Inner cylinder 1
Is made of one-piece Sialon ceramics and has an intermediate cylinder 2
Is made of integral MgO-stabilized zirconia ceramics having six heater mounting grooves on its inner peripheral surface,
The outer cylinder 3 is made of SKD-61. The dimensions of the main part of each cylinder are the values shown in Table 7.

[0084]

[Table 7]

The inner cylinder 1 and the intermediate cylinder 2 are fitted with a clearance fit, and the intermediate cylinder 2 and the outer cylinder 3 are joined by shrink fitting, so that six grooves for mounting a heater are provided in the intermediate cylinder 2. The size of each one is φ8
Heater with a heating value of 1L max.
The heating type injection molding sleeve having the structure shown in FIG. 2 was prepared, mounted on a die casting machine, and subjected to a practical use test of 100,000 shots under the casting conditions shown in Table 8.

[0086]

[Table 8]

The inner surface of the sleeve after use was observed and the amount of wear loss was measured, and the temperature inside the inner cylinder and the temperature at the boundary between the cylinders were measured during steady casting. In Fig. 2 (A)
Is the temperature measurement point. Temperature measurement location inside the inner cylinder 1 at the lower part of the sleeve Temperature measurement location at the boundary between the inner cylinder 1 and the intermediate cylinder 2 at the lower part of the sleeve Boundary between the intermediate cylinder 2 and the outer cylinder 3 at the lower part of the sleeve Temperature measurement point in the section Temperature measurement point inside the inner cylinder 1 at the top of the sleeve Temperature measurement point at the boundary between the inner cylinder 1 and the intermediate tube 2 at the top of the sleeve Intermediate tube 2 at the top of the sleeve Temperature measurement point at the boundary with the outer cylinder 3

Further, the temperature measurement result is used to simply calculate the clearance between the cylinders and the shrink fitting allowance during steady casting, and the heating effect by the heating heater and the inner cylinder 1 and the intermediate cylinder 2 are used. The heat insulation effect was confirmed by. During this test, the plunger movement is always stable, and
Observation of the inner peripheral surface of the sleeve inner cylinder after the test showed no evidence of uneven wear and erosion. Furthermore, comparing the inner diameter of the inner cylinder 1 before and after the test, the wear amount due to 100,000 shot casting, that is, the increase amount of the inner diameter was only 0.013
It was mm.

From the results of the above observation and measurement, it is considered that the sliding condition between the plunger tip 5 and the inner surface of the sleeve was extremely good, and the erosion by the molten metal was hardly caused. Next, Table 9 shows the temperature measurement results at the time of steady casting, and Table 10 shows the simple calculation result of the clearance between the cylinders at the time of steady casting using the temperature measurement results.

[0090]

[Table 9]

[0091]

[Table 10]

From this temperature measurement result, the inner cylinder 1 was sufficiently satisfied with wear resistance, corrosion resistance, wettability and strength even during casting,
Further, the intermediate cylinder 2 is in a temperature range that sufficiently satisfies the strength, and the heat received from the high-temperature molten metal in the injection hole and the heating heater.
It was confirmed that the heat insulating effect against the heat received from No. 7 is sufficient. Due to this heat insulation effect, the outer cylinder 3 made of SKD-61 is less affected by the temperature of the molten metal, and the heating heater-7
Since the heat loss of the molten metal is small due to the heat-retaining effect in the injection hole due to the heating by the inner cylinder 1 and the heat insulation effect of the inner cylinder 1 and the intermediate cylinder 2, it may be possible to cast at a heating degree relatively lower than the melting point of the molten metal. confirmed.

The temperature inside the sleeve is controlled by the heating heater.
By controlling the output of the sleeve, the temperatures at the points axially symmetrical with respect to the central axis of the sleeve are almost the same, and the warpage of the sleeve as a whole due to the difference in thermal expansion is extremely reduced. The temperature distribution was ideal. FIG. 9 shows the situation of the temperature change of the inner cylinder 1 due to the difference in each material and heating method. In the figure, SKD-61 sleeves, Sialon ceramic sleeves, and heating type Sialon sleeves are shown, all of which are shown in FIG. 2 (A) at the inner cylinder 1. The temperature change inside the lower part is shown. (Note that and in FIG. 9 show the same situation as in the case of the first embodiment of the first invention.) With reference to FIG. 9, in the case of the heating type sialon sleeve of the fourth embodiment, with respect to the target set temperature. It was confirmed that sufficient preheating was possible.

Further, as compared with the case without heating, which requires a recovery time, the temperature rapidly drops to 150 to 200 ° C. after preheating.
The heating type sleeve has an advantage that a steady temperature can be reached in a short time because the casting operation can be continuously performed without a temperature drop after preheating. Furthermore, in the case of the heating type sialon sleeve, the steady temperature can be kept at 200 ° C. or higher as compared with the steady temperature of the metal sleeve, and 130 ° C. or higher as compared with the case without heating.

Further, it can be confirmed that the temperature difference in the injection cycle is 5 to 8 ° C., which is significantly smaller in the sialon sleeve than in the metal sleeve at 50 ° C., regardless of whether or not heating is possible. That is, the heating type sialon sleeve of Example 4 is not only effective for lowering the heat retention of the molten metal but also for controlling the temperature of the molten metal in a high temperature range, which is effective for stable casting work and the like, and also shortens the lead time. It was confirmed that it was also effective in improving work efficiency.

Furthermore, in view of the difference in the amount of thermal expansion from the clearance between the cylinders and the shrinkage fitting calculation result during steady casting, the clearance between the cylinders is the same as the axis of movement of the plunger of the die casting machine. It is considered that the position accuracy and attitude accuracy with respect to the axis of the sleeve inner surface were within a range in which it could be maintained in a good state. Further, when the internal structure of the casting was observed, it had a stable structure in which fine primary crystal aluminum and eutectic structure were uniformly dispersed.

FIG. 11A-Photo 1 shows an observation photograph of the internal structure. Photo 1 shows the internal structure of a product cast by the heat-type injection molding sleeve for die casting according to Example 4, and shows a good structure in which primary crystal Al is finely and uniformly dispersed. In particular, since the inside of the sleeve is kept at a high temperature by heating with a heater and solidification starts after the molten metal is completely filled in the mold, coarse primary crystal Al is not seen at all, and primary aluminum dendrites are not observed. The arm spacing has a very fine structure in which it is finely and uniformly dispersed (see Photo 1), and it was possible to obtain a casting with dramatically improved characteristics of strength, hardness, and surface properties in terms of quality. .

(Embodiment 5 to Second Invention) The dimensions and structure of the main parts of each cylinder are the same as those of Embodiment 4, but in this Embodiment 5, the material of the inner cylinder 1 is changed to Sialon ceramics. It differs from Example 4 only in using the dense silicon nitride ceramics. As in Example 4, the inner cylinder 1 was made of an integral type dense silicon nitride ceramics, and the intermediate cylinder 2 was an integral type MgO having six heater mounting grooves on its inner peripheral surface.
A heating injection molding sleeve made of stabilized zirconia ceramics and an outer cylinder 3 made of SKD-61 was prepared, and 100,000 shots of actual use were tested under the same casting conditions as in Example 4,
After the use, the inner surface was observed and the amount of wear loss was measured to observe the internal structure of the casting.

As a result of this test, the same as Example 4 was used.
Observation of the inner surface of the inner cylinder showed no evidence of uneven wear and erosion, the amount of wear loss was 0.016 mm, the internal structure of the casting was extremely good, and it was possible to produce a casting with excellent quality. From these facts, the difference in the amount of thermal expansion between the cylinders during casting depends on the position accuracy and attitude accuracy of the sleeve between the axis of the die casting machine plunger and the axis of the inner surface of the sleeve. It is considered that the temperatures at points having an axially symmetric positional relationship with respect to the central axis were almost the same, and it was considered that the ideal temperature distribution was such that the warpage of the sleeve as a whole due to the difference in thermal expansion was extremely small.

Further, the heat loss of the molten metal is small due to the heat-retaining effect in the injection hole due to the heating by the heating heater 7 and the adiabatic effect of the inner cylinder 1 and the intermediate cylinder 2. It was confirmed that casting is possible even with a small degree of superheat. From the above, it was confirmed that even when the dense silicon nitride ceramics was used for the inner cylinder 1, the same effect as the inner cylinder made of sialon ceramics of Example 4 was obtained.

(Embodiment 6-Second Invention) FIG. 4 is a diagram for explaining another embodiment (Embodiment 6) of the second invention.
It is a typical sectional view showing the structure of the division type of the heating type injection molding sleeve for die casting. The material of each cylinder and the size of the main part are the same as in Example 4, but the inner cylinder 1 and the intermediate cylinder 2 are each divided into five parts to produce a heating injection molding sleeve having the structure shown in FIG. Under the same casting conditions as in Example 4,
An actual use test of 100,000 shots was performed, the inner surface after use was observed, the wear loss amount was measured, and the internal structure of the casting was observed.

As a result of this test, the same as Example 4 was used.
Observation of the inner surface of the inner cylinder showed no evidence of uneven wear and erosion, the amount of wear loss was 0.016 mm, the internal structure of the casting was extremely good, and it was possible to produce castings with excellent quality. . From the above, from the viewpoint of the difference in the thermal expansion amount between the cylinders during casting, the plunger of the die casting machine is
It is considered that the positional accuracy and attitude accuracy between the moving axis of the robot and the axis of the sleeve inner surface were within the range in which the sleeve could be maintained in a good state, and the temperature inside the sleeve was about the center axis of the sleeve. It is considered that the temperatures at points having an axially symmetric positional relationship in the vertical direction are almost the same, and the warp of the sleeve as a whole due to the difference in the amount of thermal expansion is extremely small, which is an ideal temperature distribution.

Further, the heat loss of the molten metal is small due to the heating by the heating heater 7 and the heat retaining effect in the injection hole due to the heat insulating effect of the inner cylinder 1 and the intermediate cylinder 2, so that it is relatively higher than the melting point of the molten metal. It was confirmed that casting is possible even with a small degree of superheat. From the above, it was confirmed that the same effect as that of the integrated structure of Example 4 was obtained even in the divided structure.

Comparative Example 1-Comparative Example Corresponding to Example 1 of the First Invention For comparison with the first invention, a double cylinder consisting of an inner cylinder and an outer cylinder, each cylinder made of SKD-61. An example of an injection molding sleeve having a structure will be given. 30 mm inner diameter and 70 mm outer diameter
Inner cylinder made of SKD-61 and SKD with inner diameter of 70 mm and outer diameter of 156 mm
A double-structured injection molding sleeve consisting of a -61 outer cylinder was attached to the same die-casting machine as in Example 1 above, and an actual use test of 20,000 shots was performed under the same casting conditions as Example 1 (see Table 4 above). After the operation, the inner surface of the sleeve was observed, the wear loss amount was measured, and the internal structure of the casting was observed.

As a result of this test, by observing the inner peripheral surface of the sleeve inner cylinder, a scar in the axial direction was confirmed on the inner surface of the sleeve. This is because the chill layer of high hardness generated by the temperature drop of the molten metal in the sleeve was rubbed between the sleeve and the plunger by the plunger drive, and it is thought that it was caused by the inner surface of the sleeve being damaged. .

The wear loss on the inner surface of the sleeve is 0.066 m.
It was as large as m. Further, according to the observation of the internal structure of the casting, a two-layer structure in which the crystallized area ratio of coarse primary crystal Al and eutectic Si shown in FIG. Further, when the crystallization time of dendrite was estimated from the coarse primary crystal aluminum dendrite arm spacing shown in Fig. 10 (C) -Photo 3, the molten metal was filled into the mold, which was completely different from the fine primary crystal dendrite phase. It is thought that it crystallized in the sleeve before it started.

In the case of the SKD-61 sleeve, it was confirmed that the inclusion of these coarse primary crystal aluminum, the fractured chill layer or the two-layer structure has an influence on the quality deterioration of the casting such as the strength deterioration. Further, in the case of casting at a molten metal temperature of 615 ° C., a malfunction of the plunger occurred due to the welding of the molten metal.

From these test results, the SKD-61 double-structured injection-molded sleeve could not be cast unless the temperature of the molten metal was raised, so that the corrosion by the molten metal was large. Further, the sliding of the plunger tip and the inner surface of the sleeve causes a large amount of wear and, in addition, the heat insulating property is poor, so that the quality of the casting is adversely affected.

[0109]

INDUSTRIAL APPLICABILITY As described in detail above, the present invention provides an inner cylinder,
(A) A material with excellent wear resistance, corrosion resistance, heat resistance, thermal shock resistance, heat insulation, strength, and wettability even at high temperatures as the (A) inner cylinder in the triple-structure melt injection molding sleeve of the middle cylinder and outer cylinder. "Sialon ceramics or dense silicon nitride ceramics" is selected, and (B) a material with excellent heat insulation and strength as an intermediate cylinder, and a coefficient of thermal expansion larger than that of the inner cylinder and smaller than that of the outer cylinder. "Zirconia-based ceramics" is selected, (C) As the outer cylinder, a material "heat-resistant metal" that is easy to design and manufacture is selected.
It is characterized by the combination of.

The present invention has the following constitutions (A) to (C).
(1) Excellent corrosion resistance, heat resistance, thermal shock resistance, and wettability with respect to high-temperature molten metal materials, (2) excellent structural strength even when the sleeve during casting is in a high temperature state, and (3) plunger
The position accuracy and attitude accuracy between the movement axis of the and the inner surface of the sleeve are extremely good, and (4) Excellent wear resistance against sliding between the planer tip and the inner surface of the sleeve. 5) Long service life, and (6) Insulation inside the sleeve injection hole
It has excellent heat retention, and (7) it can be cast even with a relatively low superheat compared to the melting point of the metal material to be cast, (8) energy saving
This is also advantageous from the viewpoint of, and (9) the excellent effect of being able to obtain a casting that is structurally and strength stable is produced.

Further, since the intermediate cylinder is made of a material having excellent heat insulating properties and strength and an appropriate coefficient of thermal expansion, (10)
Regarding joints between cylinders, press-fitting, clearance fitting, cast gurney, etc. are possible as well as shrink-fitting, and even when shrink-fitting, the shrink-fitting margin may be small, and in terms of strength against contact stress due to shrink-fitting. (11) Even if the inner cylinder and the intermediate cylinder are integrated type or divided type, the same effect occurs, and this structural feature is very advantageous in designing and manufacturing the sleeve, (12) ADC12, which is a general-purpose die casting alloy
In addition to the above, it can be applied to casting of higher melting point metal materials such as aluminum / high silicon materials and wrought materials, etc. (13) Good heat retention in sleeve holes, high temperature of molten metal Since it has excellent stability, low-speed filling method is possible,
It is possible to exert effects such as preventing gas from being entrained in the molten metal, and (14) Utilizing the heat retaining method for the application as an injection sleeve or cylinder for the two-stage pressurizing method and the molten metal forging method. Is sufficiently possible, and other effects occur.

Moreover, in the second invention, in addition to the constitutions of (A) to (C) described above, (D) heating the inside or the outer peripheral portion of the inner cylinder or the inside, the inner peripheral portion or the outer peripheral portion of the intermediate cylinder. This is characterized by the fact that a heater is attached, which allows the sleeve to be forced into an ideal temperature distribution by (15) heating with a heating heater in addition to the effects of (1) to (14) above. Therefore, (16) the warp of the sleeve due to the difference in the amount of thermal expansion is extremely small, and (17) it can be cast with a smaller superheat than the melting point of the metal material to be cast. It is possible and more advantageous from the viewpoint of energy saving, (18)
It is also applicable to casting of higher melting point metal materials, (19)
Therefore, there is a remarkable effect that it can be used as a structural system for transporting molten metal.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an integrated structure of an injection molding sleeve for die casting which is an embodiment of the first invention.

FIG. 2 is a schematic cross-sectional view showing a structure of an integral type of a heating type injection molding sleeve for die casting which is an embodiment of the second invention, wherein (A) is a cross-sectional view taken along line BB of (B). , (B) is a sectional view taken along line AA of (A).

FIG. 3 is a schematic sectional view showing the structure of a split mold of an injection molding sleeve for die casting which is another embodiment of the first invention.

FIG. 4 is a schematic cross-sectional view showing the structure of a split mold of a heating type injection molding sleeve for die casting which is another embodiment of the second invention.

FIG. 5 is a characteristic diagram showing the relationship between temperature and hardness of various materials used for the inner cylinder.

FIG. 6 is a characteristic diagram showing the relationship between temperature and longitudinal elastic modulus of various materials used for the inner cylinder.

FIG. 7 is a wear comparison test diagram showing the relationship between the lap time and wear amount of various materials used for the inner cylinder.

FIG. 8 is a characteristic diagram showing the relationship between temperature and bending strength of various materials.

FIG. 9 is a diagram showing a temperature change state of the inner cylinder with respect to various materials.

FIG. 10 is a micrograph showing the internal structure of a cast product according to Example 1 of the first invention and a conventional example.

FIG. 11 is a micrograph showing the internal structure of a cast product according to Example 4 of the second invention.

[Explanation of symbols]

 1 Inner Cylinder 2 Intermediate Cylinder 3 Outer Cylinder 4 Plunger Tip 5 Mounting Plate 6 Hot Water Supply Port 7 Heating Heater

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hisashi Nagashio 390 Higashikatagami, Bizen City, Okayama Prefecture

Claims (7)

[Claims] 1. A molten metal injection molding sleeve having a triple structure of an inner cylinder made of sialon ceramics or dense silicon nitride ceramics, an intermediate cylinder made of zirconia ceramics, and an outer cylinder made of heat-resistant metal. 2. A triple structure of an inner cylinder made of sialon ceramics or dense silicon nitride ceramics, an intermediate cylinder made of zirconia ceramics and an outer cylinder made of heat-resistant metal. A molten metal injection molding sleeve, characterized in that a heater is attached to a peripheral portion or an outer peripheral portion. 3. The melt injection molding sleeve according to claim 1 or 2, wherein the inner cylinder and the intermediate cylinder are integrally formed. 4. The molten metal injection molding sleeve according to claim 1 or 2, wherein the inner cylinder and the intermediate cylinder are molds which are divided in a direction perpendicular to or parallel to the axial direction. 5. The one of the inner cylinder and the intermediate cylinder is an integral type, and the other is a type divided into a direction perpendicular to the axial direction or parallel to the axial direction.
The molten metal injection molding sleeve described. 6. The molten metal injection molding sleeve according to claim 2, wherein the heater is mounted in parallel, at a right angle, or in a spiral direction with respect to the axial direction. 7. The melt injection molding sleeve according to claim 2, wherein the heating temperature is controlled by a heating heater alone or in each divided zone.