JPH02211961A - Die cast sleeve - Google Patents

Abstract

PURPOSE:To avert the galling of a molten metal by specifically forming three layers into an integral structure, dividing the 2nd layer to a plurality in the axial direction, superposing the divided layers on each other in the form of a socket and spigot type and grooving the superposed parts to form clearances in the axial direction. CONSTITUTION:The coefft. of thermal expansion of the metal of the 2nd layer 1b is larger than the coefft. of thermal expansion of the ceramics of the 1st layer 1a and the metal of the 3rd layer 1c and, therefore, even if the molten metal of a high-temp. is injected into the die cast sleeve 1, the generation of a clearance 1x by the difference in the thermal expansion between the 2nd layer and the 1st layer 1a on the 3rd layer 1c is suppressed. The 2nd layer 1b having the largest thermal expansion during hot is divided to a plurality in the axial direction and since the divided layers are so arranged as to form the clearances 1x in the axial direction, there are the margins for the deformation in the axial direction and the deformation by the thermal stress in the axial direction is prevented. In addition, the 2nd layers 1b have the parts where the layers are superposed on each other and the superposed parts are grooved. The layers can, therefore, be smoothly and integrally deformed in the axial direction at the time of the high-temp. expansion. The 1st layer 1a and the 2nd layer 1b adhere tightly to each other at the high-temp. time of molten metal injection and the deformation, such as camber and bend, of the ceramics of the 1st layer 1a is obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of 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 a single piece of cylindrical metal.

Alloy tool steels for hot work molds such as 5KD6 and 5KD61 were used. These metals have a relatively small amount of carbon and can withstand prolonged exposure to high temperatures around 600°C to prevent heat checks that cause cracks on the surface due to repeated expansion and contraction caused by thermal cycles of rapid heating and cooling. It is a Mo-Cr-V steel with increased chromium content to maintain hardness and wear resistance and to withstand high-temperature oxidation.

[Problems to be Solved by the Invention] Nevertheless, when casting is carried out using these integral metal cast sleeves, a solidified layer grows from the sleeve surface to the molten metal, and this solidified layer is mixed in the product. to generate 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 shocks, causing major operational problems.

In addition, the sleeve deforms 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, which prevents 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 metal, and the intermediate layer has a higher coefficient of thermal expansion than the outermost layer;

They are divided into multiple parts in the axial direction, overlapped with each other in a ■■■■ (inset) shape, grooved on either side of the overlapping surfaces, and arranged to form a gap in the axial direction. The layers were assembled 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 prevents the generation of gaps due to the difference in thermal expansion between the first layer and the third layer. The second layer, which has the largest thermal expansion when hot, is divided into multiple parts in the axial direction and arranged to form gaps in the axial direction, so there is an allowance for deformation in the axial direction. Unreasonable deformation due to thermal stress is prevented. Moreover, since the second layer has overlapping portions, and one overlapping portion is grooved, it can be deformed as one body in the axial direction without difficulty during high-temperature expansion.

In addition, even if assembled with a small shrinkage fit without requiring a large shrinkage fit during assembly, the first and second layers will stick together at high temperatures during molten metal injection, causing warping and bending of the ceramic in the first layer. Since non-uniform deformation such as this is suppressed as much as possible, it is possible to avoid damage to the ceramic and galling phenomena caused by non-uniform deformation.

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

1 to 4 show embodiments of the present invention. FIG. 1 is a longitudinal sectional view showing a die-cast sleeve according to the embodiment of the present invention. FIG. 2 is a longitudinal sectional view of a die-cast sleeve showing another embodiment of the present invention.

Figure 3 is a partially enlarged longitudinal section, and Figure 4 is Figure 3 rV-
This is a partially enlarged cross section of the IV view.

In the figure, 1 is a die-cast sleeve, la is the first layer,
1b is the second layer, and lc is the third layer. The first fila is made of ceramic, the second layer lb and the third layer 1c are made of metal, and the second layer lb is made of a material with a higher coefficient of thermal expansion than the third layer 1c. For example, the third layer 1c is made of 5KD6 or In the case of 5KD61 hot die alloy tool steel, the second layer lb is made of stainless steel, copper alloy, lead alloy, or the like. but.

The molten metal temperature is about 650℃, so at least 700℃
It is required that it does not dissolve in the following conditions.

Both the first layer 1a and the third layer 1c have a cylindrical shape and are manufactured integrally. On the other hand, the second layer lb is divided into a plurality of parts in the axial direction. To assemble these three layers, the second layer lb and the first layer 1a are integrally formed concentrically on the cylindrical inner surface of the third layer 1c by shrink fitting. At this time, as shown in Figure 1,
In the second layer ib, the thickness of the cylindrical ends is reduced to approximately half on the outer diameter side on one end and on the inner diameter side on the other end and overlapped with each other. They are joined in a so-called ■■■■ (inset) shape, and are arranged so that the end faces are not brought into close contact with each other in the axial direction while maintaining a gap lχ and a gap lχ゛. As shown in FIGS. 3 and 4, *1y is formed in the overlapping portion of the second layer lb by groove processing along the axial direction of the contact surface.

These three layers are then assembled together by shrink fitting, and the shrink fit allowance is selected so that a proper shrink fit can be achieved under high temperature usage conditions during injection of molten metal.

FIG. 2 shows another embodiment of the present invention, in which the second layer lb is divided into a plurality of parts in the axial direction with respect to the integral inner cylindrical third layer 1c, and is also divided into two or four parts in the circumferential direction. The first layer 1a is divided into a plurality of parts and stored in the third layer lc, and the first layer 1a having an integral cylindrical shape is stored inside the third layer lc.
Similarly to the figure), the second layers lb are arranged with axial gaps of 1χ and 1χ maintained between them. Assembling the three layers is the first
As in the embodiment, they are integrated by proper shrink fitting.

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, a gap lχ and a gap lχ° are provided in the second layer lb to allow for axial deformation at high temperatures, and a groove l is provided in the axial direction in the overlapping portion of the second layer lb to reduce the contact area. Therefore, each second layer lb can easily stretch and deform in the axial direction during thermal expansion at high temperatures. Therefore, generation of excessive thermal stress and deformation in the metal of the second layer lb can be avoided, and adverse effects caused by the thermal deformation of the second layer lb can also be avoided from reaching Mla.

In addition to forming the groove in an axial tooth shape as in this embodiment, various shapes such as knurling, lattice, and thread (spiral) shapes can be adopted.

[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, the second layer has a higher thermal expansion coefficient than the third layer, and is made into an integral structure by shrink fitting, and the second layer is divided into multiple parts in the axial direction. By providing an axial clearance, it can withstand repeated heat loads from pouring and cooling molten metal.

Not only can damage and uneven deformation of the inner surface of the sleeve be prevented, but also the phenomenon of molten metal leaking can be avoided, so stable and long-term continuous operation can be reliably carried out.

[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, FIG. 2 is a longitudinal sectional view showing another embodiment, FIG. 3 is a partially enlarged longitudinal sectional view of FIG. The figure is a partially enlarged cross-sectional view taken from rV-4V in FIG. 3. 1...Die-casting sleeve, 1a...1st layer, lb...2nd layer,
lc...Third layer, lχ, lχ°...gap, lso...groove. Figure 3 Figure 4 Patent applicant Ube Industries Co., Ltd.

Claims (1)

[Claims] (1) In a die-casting sleeve in which the injected molten metal is filled into the mold with an injection plunger, the die-casting sleeve has a three-layer structure divided in the radial direction, the innermost layer (first layer) is made of ceramic with good heat retention, and the middle layer is made of ceramic with good heat retention. The layer (second layer) and the outermost layer (third layer) are made of metal, the coefficient of thermal expansion of the intermediate layer is made of a metal that is larger than that of the outermost layer, and the intermediate layer is divided into multiple parts in the axial direction, and is separated from each other. ■
In addition to being placed overlapping each other in a ■■ (inset) shape,
A groove is formed on at least one of the overlapping contact surfaces to reduce the mutual contact area, and each intermediate layer is arranged to form a gap in the axial direction, and these three layers are sintered. A die-cast sleeve assembled by fitting.