JPH02211959A - Die cast sleeve - Google Patents

Abstract

PURPOSE:To prevent the galling by the failure and nonuniform deformation of ceramics by forming the 1st layer of ceramics, the 2nd layer and 3rd layer of metals, forming the 2nd layer to have the coefft. of thermal expansion larger than the coefft. of thermal expansion of the 3rd layer and forming these layers into an integral structure by shrinkage fitting. CONSTITUTION:The die cast sleeve 1 is made into the 3-layered structure divided in the radial direction. The 1st layer 1a is constituted of the ceramics having a good heat insulating characteristic, the 2nd layer 1b and the 3rd layer 1c are constituted of the metals; in addition, the 2nd layer 1b is formed of the metal having the coefft. of thermal expansion larger than the coefft. of thermal expansion of the 3rd layer 1c. These three layers are assembled by shrinkage fitting. Since the three layers are made into the integral structure, the clearance 1x of the expansion margin between the ceramics of the 1st layer 1a and the metal of the 3rd layer 1c is made up and filled by the metal of the 2nd layer 1b having the coefft. of thermal expansion larger than the coefft. of thermal expansion of the 3rd layer 1c. The three layers, therefore, maintain the integrity without separation. The 1st layer 1a adheres tightly to the 2nd layer 1b and the nonuniform deformation, such as camber and bend, is averted as far as possible. The galling by the failure and ununiform deformation of the ceramics is, therefore, averted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a die-casting sleeve for a die-casting machine used for die-casting, squeeze-casting, etc.

[Prior art] Conventionally, the injection sleeve (die-casting sleeve) of a die-casting machine is made of a single cylindrical metal, 5KD6 or 5KD6.
Alloy tool steels for hot forming, such as No. 1, were used. These metals have a relatively low carbon content and are not exposed to high temperatures around 600°C for long periods of time to prevent heat checks, which can cause cracks on the surface due to the reversal of expansion and contraction caused by thermal cycles of rapid heating and cooling. Me-Cr-, which maintains hardness and wear resistance, and has an increased amount of chromium to withstand high-temperature oxidation.
It is V steel.

[Invention tries to solve! [Problem 2] Despite this, when casting is performed using these integral metallic die-casting sleeves, a solidified layer grows from the sleeve surface into the molten metal, and this solidified layer is mixed in the product and causes casting defects. On the other hand, if ceramic is used as the material for the sleeve in order to prevent this phenomenon, the ceramic will be damaged due to repeated heat checks, resulting in major operational problems.

In addition, the sleeve is deformed due to the uneven temperature distribution that occurs within the sleeve, and as a result, molten metal is inserted between the deformed sleeve and the plunger tip, causing galling between the plunger tip and the sleeve, resulting in smooth injection. It was hindering movement.

[Means for Solving the Problems] In order to solve the above problems, the die-cast sleeve of the present invention has a three-layer structure divided in the radial direction, and the innermost layer (first layer) has a good heat retention property. Ceramic, the intermediate layer (second layer) and the outermost layer (third layer) are made of metal, and the thermal expansion coefficient of the intermediate layer is larger than that of the outermost layer, and these three layers are made of metal. I decided to assemble it by shrink fitting.

[Function] Even if high-temperature molten metal is injected into the die-casting sleeve of the present invention, the coefficient of thermal expansion of the metal of the second layer is lower than that of the ceramic of the first layer.
Since it is larger than the metal of the third layer, it suppresses the generation of gap i due to the difference in thermal expansion between the first layer and the third layer. Therefore, even if assembled with a small shrinkage fit without requiring a large shrinkage fit during assembly, the first and second layers will be in close contact even at high temperatures during molten metal injection, and the ceramic of the first layer will remain in close contact with the other layers. Since non-uniform deformation such as bending and bending is suppressed as much as possible, it is possible to avoid ceramic damage and galling caused by non-uniform deformation.

[Example] The present invention will be described in detail below based on one drawing.

FIG. 1 and FIG. 2 show an embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view showing a die-cast sleeve according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing a die-cast sleeve according to another embodiment of the present invention.

In the figure, l is the die-cast sleeve, la is the first layer,
1b is the second layer, and lc is the third layer. The first layer ``a'' is made of ceramic, the second layer lb and the third layer 1c are made of metal, and the second layer ``a'' is made of ceramic.
Layer lb is made of material 1 with a higher coefficient of thermal expansion than 113 layer 1c.
For example, when the third layer 1c is made of 5KD6 or 5KD61 hot work die alloy tool steel, the tjIJz layer lb is made of stainless steel or copper alloy.

Adopt lead alloy, etc. However, the molten metal temperature is approximately 650℃
Therefore, it is required that the material does not dissolve at least below 700°C.

The second layer lb and the third layer 1c are manufactured in a cylindrical shape, and the third layer l
As shown in FIG. 1, they are integrally formed concentrically on the inner surface of the cylinder c by shrink fitting. The shrink fit allowance is selected so that a proper shrink fit can be achieved under high temperature usage conditions when pouring molten metal.

FIG. 2 shows another embodiment of the present invention, in which the second layer tb is formed into two or four parts with respect to the integral inner cylindrical third layer lc, and is housed in the third layer 1c. The first part has an integral inner cylinder shape.
Layer 1a is housed inside second layer lb. At this time, the second layer lb is shortened so that an axial gap lχ is created between the second layer lb and the third layer 1c at room temperature, and the assembly of these three layers is performed appropriately as in the first embodiment. It is made into one piece by shrink fit.

By configuring as above, the first embodiment (first
In both the second embodiment (Fig. 2) and the second embodiment (Fig. 2), the three layers are integrated in advance with a moderate shrinkage fit that is not excessive under high-temperature usage conditions, so when pouring the molten metal, the first layer The gap between the expansion allowance between the ceramic and the third layer of metal is filled by the second layer of metal, which has a higher coefficient of thermal expansion than the third layer, so the three layers remain integrated without separating. The first layer of ceramic is in close contact with the second layer, and uneven deformation such as warping or bending is avoided as much as possible. Therefore, galling phenomena caused by ceramic breakage and uneven deformation are prevented.

In addition, in the second embodiment, since the second layer lb is provided with a gap lχ as an axial deformation allowance at high temperatures, the second layer lb
The generation of excessive thermal stress on the metal b can be avoided.

[Effects of the Invention] The die-casting sleeve of the present invention includes ceramic in the first layer,
The second and third layers are made of metal, and the second layer has a higher coefficient of thermal expansion than the third layer, and is made into an integral structure by shrink fitting, so it can withstand repeated thermal loads of molten metal injection and cooling. Even though
Not only can damage and uneven deformation of the inner surface of the sleeve be prevented, but also galling of the molten metal can be avoided, ensuring stable, long-term continuous operation.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a die-cast sleeve according to the present invention, and FIG. 2 is a longitudinal sectional view showing another embodiment. 1...Die-casting sleeve, la...First layer, 1b...Second layer. IC...Third layer, lχ...Gap. Patent applicant: Ube Industries, Ltd.

Claims (1)

[Claims] (1) In a die-casting sleeve in which the injected molten metal is filled into a mold with an injection plunger, the die-casting sleeve has a three-layer structure divided in the radial direction, and the innermost layer (first layer)
is made of ceramic with good heat retention, the middle layer (second layer) and the outermost layer (third layer) are made of metal, and the middle layer is made of a metal whose coefficient of thermal expansion is larger than that of the outermost layer. A die-cast sleeve characterized by assembling these three layers by shrink fitting.