JP2000202608A - Plunger sleeve for die casting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the rapid cooling of molten metal for supplying, to prevent the local solidification of the molten metal and to minimize the enclosure of gas generated with the thermal decomposition of lubricant by joining and integrating a two-layer structural cylinder which constitutes an outer casing member with a heat resistant metallic cylindrical body and the whole length or a partial range in the axial direction of an inner casing member with a porous cylindrical body. SOLUTION: The constitution of a plunger sleeve is joined and integrated to the two-layer structural cylinder 3 which arranged the porous cylindrical body 1 as the inner casing member over the whole length of the axial direction and laminating the heat resistant metallic cylindrical body 2 as the outer casing member on the outer periphery of the inner casing member. Further, a ceramic base porous cylindrical body 1A is applied to the rear side range portion of the inner casing member and a metal base porous cylindrical body 1B is applied to the front side range portion. Furthermore, at the one end part of a spiral groove 6 formed in the outer peripheral part of the porous cylindrical body 1, a lubricant press-in hole 7 is bored so as to penetrate the heat-resistant metallic cylindrical body 2. The lubricant is pressed into the spiral groove 6 from the lubricant press-in hole 7 with a lubricant press-in pump and impregnated into the porous cylindrical body 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger sleeve for a die casting machine for performing casting by pressing a non-ferrous metal melt such as an aluminum alloy into a cavity of a die via a plunger.

[0002]

2. Description of the Related Art Conventionally, as a plunger sleeve for a die casting machine, a cast product such as tool steel (SKD61, SKD11) having corrosion resistance to molten metal and wear resistance to repetitive sliding of a plunger tip, or a nitriding treatment. Is used. In addition, ceramics such as silicon nitride and N
It has also been proposed to apply a sintered product such as an i-based cermet. Further, in order to impart lubricity to the sleeve and the tip, a lubricant may be added every cycle before the molten metal is supplied.

[0003]

In order to improve and stabilize the quality of the die castings cast as described above, the molten metal supplied in the plunger sleeve is melted under a healthy molten fluid state. It is necessary to press-fit the molten metal into a die, but when the molten metal is brought into contact with the plunger sleeve, it is rapidly cooled and local solidification may occur in the molten metal. The locally solidified portion of the molten metal is cast into the cavity of the mold as it is together with the molten metal, which is one of the causes of causing defects in the die-cast product. Also, an oil lubricant is added to provide lubricity between the sleeve and the chip, but oil decomposes in the sleeve due to high heat and gas is generated, and the molten metal is entrained in the gas, which impairs the quality of the die cast casting. , Causing a decrease in mechanical properties such as ductility. The present invention has been made in view of the above problems, and suppresses rapid cooling of molten metal supplied to a plunger sleeve to eliminate local solidification of molten metal and to generate gas generated by thermal decomposition of a lubricant. It is an object of the present invention to provide a plunger sleeve for a die-casting machine, which minimizes entrainment of the plunger.

[0004]

In order to achieve the above-mentioned object, a plunger sleeve for a die-casting machine according to the present invention comprises an exterior member formed of a heat-resistant metal cylinder and a part of the entire length of the interior member or a partial area in the axial direction. And a two-layer structure cylinder constituted by a porous cylinder is joined and integrated.

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, in FIG. 1A, a porous cylindrical body 1 is provided as an interior member over the entire length in the axial direction, and a heat-resistant metal cylindrical body 2 is provided as an exterior member on the outer periphery thereof.
Are joined and integrated. In addition, the code | symbol 4 in a figure is a hot water supply port of a molten metal, and the code | symbol 5 is a plunger. 1B, the ceramic porous cylinder 1A is applied to the rear (right side in the figure) region of the interior member, and the metal porous cylinder 1B is applied to the front (left side) region. Is applied. Otherwise, the configuration is the same as that of FIG.

In FIG. 1C, a spiral groove 6 is formed on the outer periphery of the porous cylindrical body 1 as an interior member, and a lubricant press-in hole 7 is formed at one end of the spiral groove 6 with an exterior member. The heat-resistant metal cylindrical body 2 is perforated.
The lubricant press-in hole 7 is connected to a lubricant pump (not shown), and has a mechanism in which the lubricant is press-fitted and impregnated and held in the pores of the entire porous cylindrical body 1 through the spiral groove 6. Otherwise, the configuration is the same as that of FIG.

(Pore of Porous Cylindrical Body) The porous cylindrical body 1 of the plunger sleeve having the above structure has a porosity of at least 0.5% from the viewpoint of a heat insulating effect of suppressing rapid cooling of molten metal.
It is necessary to have a porosity of 7% or more that can hold the lubricant impregnated together with the heat insulating effect.
As the porosity is increased, the heat insulating effect and the supply of the lubricant are improved. However, an excessive increase in the porosity results in a decrease in the strength and wear resistance of the porous cylindrical body. Is appropriate. The larger the pore diameter is, the more advantageous from the viewpoint of the supply of the lubricant. However, as the pore diameter becomes larger, the insertion of the molten metal into the pores and the damage of the member due to the insertion become easier. For this reason, the pore diameter is preferably 200 μm or less.

(Material of Porous Cylindrical Body) Next, as the porous cylindrical body 1, a porous sintered body such as a metal type, a ceramic type or a composite thereof is applied. As examples of the material type, in the metal system, tool steel (SKD61, SKD11, etc.), stainless steel (SUS304, SUS430, etc.), high speed steel (SKH51, SKH55, etc.), maraging steel (1
8Ni-based, 20Ni-based, etc.), Co-based alloys (Tribaloy, etc.), Ni-based alloys (Cormoloy, Hastelloy, Inconel, etc.), and ceramics-based nitride ceramics (eg, silicon nitride, aluminum nitride, boron nitride), carbides Ceramics (for example, silicon carbide), boride ceramics (for example, titanium boride), and the like, and composite sintered bodies thereof, and cermets include titanium nitride-molybdenum alloy, tungsten carbide-cobalt, titanium carbide-titanium alloy, and the like.

(Manufacture of Porous Cylindrical Body) Next, as a method of manufacturing the porous cylindrical body 1 using the above-described material type, for example, the above-described raw material powder is pressure-molded under hydrostatic pressure. There is a method of sintering the green compact, and the particle size of the raw material powder does not need to be different from that usually used as a sintering raw material, but is relatively coarse (for example, 40 to 1000).
μm) allows pores having a large diameter to be distributed in the porous cylindrical body 1.

In the above case, the pressing of the raw material powder is carried out by cold isostatic pressing (CIP) in order to ensure the homogeneity of the green compact.
Molding) is preferably applied. In the sintering process, the atmospheric conditions and the sintering temperature in the production of a normal high-density sintered body can be applied. For example, when manufacturing the ceramic-based porous cylindrical body 1A, the CIP molding is performed with a pressing force of about 50.
The sintering of the green compact is performed at a pressure of normal pressure to 0.9 MPa and a temperature of 1700 to 1 MPa.
At 850 ° C., a porous sintered body can be obtained.

(Manufacture of Two-Layer Structure Cylinder) Next, when manufacturing the two-layer structure cylinder 3, necessary mechanical processing is performed on the porous cylindrical body 1 obtained as described above as an interior member, and attached parts are assembled. . The porous cylindrical body 1 and the heat-resistant metal cylindrical body 2 prepared as the exterior member are assembled by joining together by shrink fitting and press fitting. The interior member 1 is subjected to a surface modification treatment (for example, a nitriding treatment) to increase the hardness of the inner peripheral surface and enhance the wear resistance, if desired. The treatment may be performed in the same manner as the treatment of a conventional plunger sleeve made of tool steel or the like.
The treatment is performed under the condition that the temperature is maintained at about 20 Hr.

(Test Example) Ceramic powder (spray dryer granulated powder obtained by adding 5% of an organic binder to a composite powder containing 75 parts of silicon nitride, 15 parts of boron nitride, 6 parts of yttria, and 4 parts of alumina) was formed into a rubber type. Enclosed CIP
A green compact was formed by molding (pressing force: 1.5 ton / cm ³ ), and this was subjected to a sintering treatment (temperature: 1800 ° C., nitrogen pressurization: 0.8 MPa, time: 4 Hr) to obtain a ceramic porous material. A cylindrical body 1A was obtained. The spiral groove 6 as shown in FIG. 1 (c) may be machined after sintering. To obtain the metal-based porous cylinder 1B,
The metal powder was CIP-molded in the same manner as above to obtain a green compact, and then subjected to nitriding treatment (holding at 550 ° C. for 2 hours in ammonia gas) to obtain a metal-based porous cylindrical body 1B.

The porous cylindrical body 1 obtained as described above
FIG.
A concentric two-layer structure cylinder 3 as shown in (b) is manufactured,
Thereafter, the plunger sleeve was finished by machining (the sleeve is hereinafter referred to as a sleeve A). The specifications of the sleeve A and the porous properties of the porous cylindrical body 1 are as follows. Sleeve size (mm): hole diameter 60, thickness 12 of porous cylinder 1, heat-resistant metal cylinder 2
Thickness 13 and shaft length 250. Porous cylinder: porosity 12
%, Open porosity 8%, pore size distribution 7 μm under, average pore size 8
μm. Interior surface hardness: Hv350.

Comparative Example As a comparative example, a conventional tool steel SK was used.
A sleeve (nitriding material) made of D-61 was prepared (hereinafter, this sleeve will be described as sleeve B). The diameter, thickness, length, etc. of the sleeve B were the same as those of the sleeve A.

(Adiabatic Test) FIG. 2 shows the results of injecting molten aluminum alloy (AC-4C) into the sleeve A of the present invention and the sleeve B of the prior art, and measuring the change over time in the molten metal temperature. The sleeve A of the present invention has a lower temperature drop of the molten metal than the conventional sleeve B, and is excellent in heat insulation.

(Casting test) A casting test of an aluminum alloy casting was performed by a cold chamber die casting machine under the following conditions. Cast alloy: JIS H5302ADC-10 (Cu3.
0, Si 8.0, balance Al), casting temperature: 700 ° C. (sleeve hot water temperature), casting speed: 100 cm / sec, casting pressure: 250 ton, casting size: 100 × 150 ×
15 (maximum thickness) mm.

(Casting Results) The results of measuring the presence or absence of a cavity, the presence or absence of a fractured chill layer, and the gas content (cc / 100 g) of the die casting obtained as described above are shown in Table 1.
Shown in The gas content was determined by a method in which a sample was heated and dissolved to measure the amount of released gas. Also, in Table 1, the present invention (a) has the structure shown in FIG. 1 (a), the present invention (c) has the structure shown in FIG. 1 (c), and the comparative example shows the same tool steel SKD as described above. A sleeve obtained by nitriding -61 was used.

[Table 1]

From the above casting results, the sleeve of the present invention (a)
Die castings cast using (c) are superior to die castings cast using conventional tool steel sleeves in that they have less gas content, no casting cavities, and almost no fractured chill layers. You can see that it has been cast. This is presumably because the fine pores of the sleeve of the present invention suppress generation of gas and have a high heat insulating effect. Comparing the amount of the plunger lubricant added, the conventional one had to add 2 cc / shot, whereas the sleeve (a) of the present invention required 0.7 cc / shot to seize the plunger tip. Good with little abnormal wear. Further, in the present invention (c), 0.5 cc
/ Shot was good with little seizure of plunger tip and abnormal wear.

[0019]

As is apparent from the above description, the present invention has a two-layer structure in which the exterior member is constituted by a heat-resistant metal cylinder and the entire length of the interior member or a part of the axial direction is constituted by a porous cylinder. Since it is a plunger sleeve for a die casting machine with a structure in which the cylinders are joined and integrated, gas generation is suppressed, and a rapid temperature drop of the molten metal can be prevented by the heat insulation effect.
There is an excellent effect that a high quality and stable casting can be cast.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a plunger sleeve for a die casting machine showing three kinds of embodiments of the present invention.

FIG. 2 is a graph showing the relationship between the time after the molten metal is injected into the sleeve A of the present invention and the conventional sleeve B and the temperature of the molten metal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Porous cylinder 1A Ceramic-based porous cylinder 1B Metal-based porous cylinder 2 Heat-resistant metal cylinder 3 Double-layered cylinder 6 Spiral groove 7 Lubricant press-in hole

Claims (5)

[Claims] 1. A die-casting wherein an exterior member is constituted by a heat-resistant metal cylinder and a two-layer structure cylinder is constituted by joining a two-layer structure cylinder constituted by a porous cylinder for the entire length or a partial area in the axial direction of the interior member. Plunger sleeve for machine. 2. A plunger sleeve for a die casting machine according to claim 1, wherein said porous cylindrical body is a sintered body made of a single body of metal or ceramics or a composite body thereof. 3. The porosity of the porous cylindrical body is 0.5 to 40.
The plunger sleeve for a die casting machine according to claim 1 or 2, wherein the pore diameter is 200 µm or less. 4. A plunger sleeve for a die casting machine according to claim 1, wherein the pores of said porous cylindrical body are impregnated with a plunger lubricant. 5. A spiral groove is formed on an outer periphery of said porous cylindrical body, and a lubricant press-in hole is provided at one end of said spiral groove so as to communicate therewith. Plunger sleeve for die casting machines.