JPH02211960A - Die cast sleeve - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a die-casting sleeve for a die-casting machine used for die-casting, squeeze-casting, etc.

[Prior art] In the past, the injection sleeve (die-casting sleeve) of a die-casting machine is a one-piece cylindrical metal, 5KD6 or 5KD6.
Alloy tool steels for hot molds such as No. 1 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. Mo-Cr- with increased chromium content to maintain hardness and wear resistance and to withstand high temperature oxidation.
It is V steel.

[Problem to be solved by the invention] Nevertheless, when casting is performed using these integral metallic die-cast sleeves, a solidified layer grows from the sleeve surface to the molten metal, and this solidified layer is mixed in the product. Generates 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 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, the intermediate layer has a higher coefficient of thermal expansion than the outermost layer, and is divided into multiple parts in the axial direction. The three layers were arranged so as to form a gap in the axial direction, and these three 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 a plurality of parts in the axial direction and arranged so as to form gaps in the axial direction.

Since there is a deformation allowance in the axial direction, unreasonable deformation due to thermal stress in the axial direction is prevented. In addition, even if a large shrink fit allowance is not required during one assembly, and even if the assembly is assembled with a small shrink fit allowance, the first and second layers will be in close contact with each other at the high temperature of molten metal injection, and the ceramic of the first layer will warp or bend. 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.

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 of a die-cast sleeve showing 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 1a is made of ceramic, the second layer lb and the third layer IC are made of metal, and the second layer 1a is made of ceramic.
Layer lb is made of a material with a higher coefficient of thermal expansion than the third layer IC. For example, when the third layer is made of hot-work mold alloy tool steel such as KD6 or 5KD61, the second layer lb is made of stainless steel or copper. Alloy, lead alloy, etc. shall be used. However, since the molten metal temperature is about 650℃, at least 70℃
It is required that it does not dissolve at temperatures below 0°C.

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 fourth layer IC 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,
The second layer lb is made by thinning the wall thickness of the cylindrical ends by approximately half on the outer diameter side at one end and half on the inner diameter side at the other end and overlapping each other in a so-called inlay (inset) shape, and the end face in the axial direction. Arrange them so that they do not come into close contact and maintain a gap lχ. 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 lb is divided into a plurality of parts in the axial direction of the integrated inner cylindrical third layer IC, 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 an axial gap lχ maintained therebetween. As in the first embodiment, the three layers are assembled together 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 skin or bending is avoided as much as possible. Therefore, f)s due to ceramic breakage and uneven deformation.
Prevent C4J phenomenon.

l...Die-casting sleeve.In addition, the second layer lb has an axial deformation allowance at high temperatures la...
・First layer, 1b...Second layer.

Since the gap lχ is provided, it is possible to avoid generation of excessive thermal stress and deformation in the metal of the second layer ib, and the adverse effects caused by the thermal deformation of the second layer ib can be applied to the first layer 1a. 3 layers,

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 a ceramic with good heat retention, the middle layer (second layer) and the outermost layer (third layer) are metal, and the coefficient of thermal expansion of the middle layer is a metal that is larger than that of the outermost layer, and in the axial direction. A die-cast sleeve is characterized in that it is divided into multiple parts, arranged to form a gap in the axial direction, and then assembled by shrink fitting these three layers.