JPH10263783A - Wear resistant parts and manufacture thereof, and parts for casting machine and die casting machine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wear resistant parts and a parts for casting machine which can stably maintain the wear resistance and the erosion resistance for a long term even in the case of using e.g. under such a severe condition as to contact with molten metal. SOLUTION: In the parts 1 having the wear resistant surface 1a needing the wear resistance or the contact surface with the molten metal and composed of composite dispersing at least one kind of compound grains selected from metal nitride, metal oxide, metal boride, metal carbide and these complex compound in metallic matrix, the compound grains are formed as inclined composition so that the vol. ratio of the compound grains in the metallic matrix reduces in the thickness direction of the parts from the wear resistant surface or the contact surface with the molten metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear-resistant part, a method of manufacturing the same, a part for a casting machine, and a die-casting machine using the same.

[0002]

2. Description of the Related Art A die-cast product made of a light metal material such as Al is placed in a cavity formed by a pair of dies.
It is manufactured by pressure filling a molten metal poured from a pouring port provided in an injection sleeve with a plunger.
In a cold-chamber die-casting machine used for manufacturing such a die-cast product, SKD61 tool steel is generally used as a constituent material of an injection sleeve, a mold, and the like, which come into contact with a light metal melt.

[0003] By the way, the above-mentioned die-cast component made of SKD61 tool steel has a surface which is in contact with a molten metal such as an Al-based molten metal as it is, for example, an inner peripheral surface (inner diameter side surface) of an injection sleeve having a substantially cylindrical shape. Since the erosion by the molten metal occurs in a relatively short time, nitriding treatment is generally performed on the contact surface with the molten metal. By this nitriding treatment, a nitride layer containing a nitride such as iron or chromium having a thickness of about 50 to 200 μm is formed on the surface layer of the SKD61 tool steel, and the reaction with the molten metal is suppressed.

However, die casting machine parts such as an injection sleeve and a mold come into contact with a molten metal such as 923 K or more, so that nitrogen diffusion is promoted and a nitride layer is decomposed. There is a problem that tool steel is gradually eroded. As described above, in the conventional nitriding treatment, the decomposition of the nitrided layer proceeds during use, so that the erosion resistance cannot be stably maintained for a long period of time.

[0005] Carburizing is also considered to be performed instead of the above-described nitriding. However, in a normal carburizing, carbon diffuses throughout the base material, and a carbide layer that can suppress the reaction with the molten metal can be suppressed. Cannot be formed. For this reason, components for casting machines such as injection sleeves and dies of die-casting machines are improved in erosion resistance to molten metal such as Al-based metal, and the long-term reliability of the erosion resistance is improved. Is required.

In response to the above demands, injection sleeves and the like are made of a ceramic material having excellent erosion resistance and abrasion resistance, or ceramic powder having excellent erosion resistance and a metal such as Ti alloy. Attempts have been made to manufacture injection sleeves and the like from composite materials with materials, specifically, composite materials to which powder sintering has been applied (Japan Die Casting Conference, 1994, pp 121-125). However, an injection sleeve or the like made of a ceramic material has low mechanical strength and toughness, which makes it difficult to handle, and has a problem of insufficient reliability. On the other hand, injection sleeves made of a composite material of ceramic powder and a metal material have improved fracture toughness, etc., compared to ceramics alone.However, ceramic powder is dispersed throughout the composite material using conventional powder sintering. Therefore, it is unavoidable that the material becomes brittle as compared with a normal metal material, which causes a decrease in reliability.

On the other hand, in particular, the injection sleeve of a die-casting machine is required to have abrasion resistance against sliding of a plunger tip. However, in the case of a conventional nitriding SKD61 tool steel, an initial nitride layer is present on the surface layer. Although it has good abrasion resistance at the stage, there is a problem that when the hardness is reduced by the decomposition of the nitride layer, the abrasion proceeds rapidly. As described above, although the surface nitriding treatment for the metal material basically contributes to the improvement of the wear resistance, the wear proceeds rapidly under severe conditions such as the decomposition of the nitride layer proceeds. It has such a problem.

[0008]

As described above, in a conventional wear-resistant part provided with wear resistance by a surface nitriding treatment or the like, under severe conditions in which the decomposition of the nitrided layer progresses rapidly, There was a problem that abrasion progressed. In particular, in a casting machine part that comes in direct contact with a molten metal, such as an injection sleeve of a die casting machine, A
There is a problem of erosion of the contact surface with l-based metal melt, etc.
There is a need for a casting machine part that can maintain good erosion resistance to a molten metal for a long period of time.

SUMMARY OF THE INVENTION The present invention has been made to address such a problem, and has a stable abrasion resistance for a long period of time even when used under severe conditions such as contact with a molten metal. It is an object of the present invention to provide a wear-resistant part and a method for producing the same that can be maintained in a molten state, and have excellent erosion resistance to a molten metal such as an Al-based molten metal. An object of the present invention is to provide a casting machine part that can be maintained for a long period of time, and a highly reliable die casting machine using the same.

[0010]

According to the first aspect of the present invention, there is provided a wear-resistant part having a wear-resistant surface requiring abrasion resistance, a metal nitride, and a metal oxide. Abrasion-resistant parts comprising a composite material in which at least one compound particle selected from a compound, a metal boride, a metal carbide and a composite compound thereof is dispersed in a metal matrix, wherein the compound particles are The composition is characterized in that the composition is gradient from the wear-resistant surface to the thickness direction of the component so that the volume ratio of the compound particles in the metal matrix decreases. In the wear-resistant part of the present invention, as described in claim 2, the part has a cylindrical shape, and an inner peripheral surface of the cylindrical part is the wear-resistant surface. It is particularly effective in such cases.

According to a third aspect of the present invention, there is provided a method for manufacturing a wear-resistant part, which has a cylindrical shape and has a wear-resistant surface whose inner peripheral surface is required to have wear resistance. In producing a wear-resistant part having the following, at least one selected from a metal nitride, a metal oxide, a metal boride, a metal carbide and a composite compound thereof is contained in a molten metal matrix material mainly constituting the part. Inject the seed compound particles,
The method is characterized by comprising a step of preparing a composite material melt and a step of producing the cylindrical component by centrifugal casting using the composite material melt.

A casting machine part according to the present invention has a contact surface with a molten metal, and comprises a metal nitride,
At least one compound particle selected from metal oxides, metal borides, metal carbides and composite compounds thereof,
A part for a casting machine made of a composite material dispersed in a metal matrix, wherein the compound particles are arranged such that a volume of the compound particles in the metal matrix in a thickness direction of the part from a contact surface with the molten metal. It is characterized in that the composition is graded so that the rate decreases. In the casting machine part of the present invention, as described in claim 5, the part has a cylindrical shape, and an inner peripheral surface of the cylindrical part is a contact surface with the molten metal. It is particularly effective in such cases.

Further, the die casting machine of the present invention is characterized in that
As described in the above, a pair of molds, one of which is movable, an injection sleeve connected to a fixed mold of the pair of molds, and also serves as a pouring receiver and a pressure cylinder, In a die casting machine including a plunger for pressure-filling the molten metal poured into the pair of dies and a driving mechanism for the plunger, at least one selected from the pair of dies and the injection sleeve includes:
It is characterized by comprising the casting machine part of the present invention described above.

In the wear-resistant parts and casting machine parts of the present invention, compound particles having high hardness, exhibiting excellent wear resistance, and further having excellent erosion resistance and the like, are incorporated in a metal matrix. A composite material having a composition gradient in the thickness direction and dispersed is used. According to such a composite material, the wear resistance and erosion resistance of the component can be sufficiently increased by the compound particles concentrated on the wear-resistant surface and the contact surface side with the molten metal, and the metal material can be improved. Even when used under severe conditions such as contact with the molten metal, it is possible to suppress the deterioration over time such as abrasion resistance and erosion resistance due to the disappearance of the compound particles, etc. It is possible to suppress a decrease in target strength and reliability.

For example, compound particles usually have a lower coefficient of thermal expansion than a metal matrix, and when a compound is formed as a general coating layer, the compound particles are easily peeled off based on the above-mentioned difference in thermal expansion. In the above, the compound particles are dispersed in the metal matrix and the composition is graded in the thickness direction. Etc. can be prevented. Further, since the compound particles have a composition gradient in the thickness direction, the original characteristics of the metal matrix can be fully utilized.

[0016]

Embodiments of the present invention will be described below.

First, an embodiment of a wear-resistant component of the present invention will be described with reference to FIG. The wear-resistant component 1 shown in FIG. 1 has a cylindrical shape, and its inner peripheral surface (inner diameter side surface) 1a is a wear-resistant surface. This wear-resistant part 1
Is at least one selected from metal nitrides, metal oxides, metal borides, metal carbides, and composite compounds thereof, which have high hardness, excellent wear resistance, light weight, and excellent erosion resistance. It is composed of a composite material in which seed compound particles are dispersed in a metal matrix with a composition gradient.

That is, as shown in FIG. 2, the compound particles which contribute to the improvement of the abrasion resistance, the erosion resistance and the like of the inner peripheral surface 1a are reduced from the inner peripheral surface 1a to the thickness t of the abrasion resistant part 1 as shown in FIG. In the direction, in other words, from the inner peripheral surface 1a to the outer peripheral surface 1b, the composition is gradient so that the volume ratio of the compound particles in the metal matrix decreases. The compound particles are concentrated on the inner peripheral surface 1a and the vicinity thereof, and form a region (high-concentration compound region) 2 containing the compound at a high concentration in the surface layer portion including the inner peripheral surface 1a.

As described above, the compound particles are dispersed in the wear-resistant part 1 with a composition gradient so that the high-concentration compound region 2 is formed on the surface layer including the inner peripheral surface 1a as the wear-resistant surface. By making (present), the inner peripheral surface 1a can be provided with excellent abrasion resistance, erosion resistance, and the like based on the hardness, abrasion resistance, and the like of the compound particles. In addition, since the compound particles have a composition gradient in the thickness t direction, embrittlement of the metal matrix mainly constituting the wear-resistant part 1 can be suppressed, and the compound particles are concentrated. Cracking or deformation due to a difference in thermal expansion between the high-concentration compound region 2 and the region (inner region) where the metal matrix is dominant can be prevented.

That is, when the compound particles are dispersed throughout the metal matrix, it is inevitable that the metal particles become brittle due to the compound particles. However, by compounding the compound particles as in this embodiment,
In a region near the outer peripheral surface 1b, the volume ratio of the compound particles is low,
Alternatively, since the compound particles are scarcely present, the properties inherent to the metal matrix can be sufficiently obtained in such a region. Accordingly, the mechanical strength and the like of the metal matrix as a whole can be sufficiently maintained as the wear-resistant component 1 as a whole, and a decrease in reliability and the like can be prevented.

When the compound particles are present, for example, as a coating layer, although the above-mentioned problem of brittleness can be solved, the compound particles usually have a larger coefficient of thermal expansion than the metal matrix, so Due to the difference in thermal expansion from the metal matrix, the compound coating layer is easily peeled off under a large temperature change such as in contact with the molten metal. On the other hand, the compound particles are dispersed in the metal matrix as in this embodiment, and further, the dispersion amount of the compound particles is made to have a composition gradient, so that the high concentration compound region 2 existing in the surface layer portion including the inner peripheral surface 1a and the metal are dispersed. The difference in thermal expansion from the region where the matrix is dominant (the internal region) can be reduced. Accordingly, cracking, deformation, and the like caused by the high-concentration compound region 2 can be prevented, and abrasion resistance, erosion resistance, and the like by the high-concentration compound region 2 can be stably obtained over a long period of time.

As the compound particles as described above, at least one selected from metal nitride particles, metal oxide particles, metal boride particles, metal carbide particles, and composite compound particles thereof is used. Examples of the metal nitride include silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), titanium nitride (TiN), and chromium nitride (CrN). As the metal oxide, alumina (Al ₂ O ₃ ),
Chromium oxide (Cr ₂ O ₃ ), cerium oxide (Ce
₂ O ₃ ), magnesia (MgO) and the like; metal borides such as iron boride (FeB), chromium boride (CrB) and zirconium boride (ZrB); and metal carbide as chromium carbide (Cr ₂ O). ₇ ), titanium carbide (TiC), zirconium carbide (ZrV), vanadium carbide (VC) and the like.

All of these metal compound particles have high hardness, exhibit excellent abrasion resistance, and are also excellent in erosion resistance and the like. In addition, both have specific gravity
7 or less, which is lighter than Fe-based alloys and the like. As described above, since the compound particles are lightweight, by applying the centrifugal casting method described in detail below,
The dispersion state having the composition gradient as described above can be easily obtained.

As the above-mentioned compound particles, those having an average particle diameter in the range of 30 to 500 μm are preferably used. If the average particle size of the compound particles is less than 30 μm, the effect of improving the abrasion resistance or the like may not be sufficiently obtained, and it may be difficult to concentrate the particles by a centrifugal casting method described later.
On the other hand, when the average particle size of the compound particles exceeds 500 μm,
Dropping and the like are likely to occur, and when centrifugal casting is applied, even if it is thrown into a molten metal, it floats, making it difficult to uniformly disperse. In particular, in order for the compound particles to be concentrated on the inner peripheral surface 1a side by the centrifugal casting method, it is desirable that the compound particles have an average particle diameter of 100 μm or more.

The compound particles are preferably dispersed in the metal matrix in a total amount of 2 to 10% by volume. If the volume ratio of the compound particles as a whole is less than 2% by volume, even when the composition is gradient, the effect of improving the characteristics of the wear-resistant surface may not be sufficiently obtained. If it exceeds, the metal matrix tends to become brittle.

Further, the degree of the composition gradient of the compound particles ranges from the abrasion-resistant surface (the inner peripheral surface 1a in this embodiment) to about 1/4 to 1/2 of the wall thickness t. Is preferably formed. If the thickness of the high-concentration compound region 2 is too large, the above-mentioned difference in thermal expansion may not be able to be sufficiently reduced. On the other hand, if the thickness is too small, characteristics such as abrasion resistance of the abrasion-resistant surface and compatibility with dissolution may be reduced. In some cases, it cannot be improved sufficiently. By setting the volume ratio of the compound particles in such a high-concentration compound region 2 to about 5 to 30% by volume, the characteristics of the wear-resistant surface can be sufficiently enhanced,
In addition, such characteristics can be stably maintained over a long period of time.

The metal matrix mainly constituting the wear-resistant part 1 is appropriately selected according to the use of the wear-resistant part 1 and the like. In particular, an Fe-based alloy such as cast iron or cast steel is mechanically used. It is preferably used from the viewpoint of strength and abrasion resistance. In particular, when the centrifugal casting method is applied to the production of the wear-resistant component 1, a cast iron or an Fe-based alloy satisfying a cast steel composition is preferably used.

The above-described wear-resistant part 1 can be easily and reproducibly obtained by applying a centrifugal casting method. As described above, since the compound particles have a lower specific gravity than, for example, an Fe-based alloy or the like constituting a metal matrix, when solidified by centrifugal casting, the compound particles gather at the rotation center side, and the compound particles are inclined to the rotation center side. A region where the particles exist at a high concentration (high concentration compound region 2) can be formed.

That is, first, at least one selected from the above-mentioned metal nitrides, metal oxides, metal borides, metal carbides and composite compounds thereof is introduced into a molten metal (metal melt) of a metal matrix material such as an Fe-based alloy. Is charged to prepare a composite material melt (turbid melt). The shape and the input amount (dispersion amount) of the compound particles are as described above.

Using such a molten composite material, the wear-resistant part 1 is formed by a horizontal centrifugal casting machine as shown in FIG.
Is prepared. The centrifugal casting device 11 shown in FIG.
A mold 14 having a desired shape held by a casting flask 13 is disposed on the mold 2. Then, from the molten metal receiver 15 arranged on the side surface of the mold 14,
A composite material melt (turbid melt) 16 is injected. here,
As the mold 14, it is preferable to use a sand mold capable of obtaining an appropriate coagulation rate for causing the compound particles to have a composition gradient, and the number of revolutions of the mold 14 depends on its diameter and the like.
Preferably, it is set to about 500 rpm. That is, when a sand mold is used, it is preferable to set conditions so that the gravity multiple is about 60 to 75G.

In the centrifugal casting apparatus 11 as described above, the molten composite material (turbid molten metal) 16 is poured into the rotating mold 14, and the molten composite material 16 is solidified while rotating. To produce a functional part.
At the time of the solidification, the metal particles having a large specific gravity are solidified, and the compound particles having a small specific gravity are concentrated on the rotation center side, that is, in the case of the cylindrical wear-resistant part 1, on the inner peripheral surface 1a side. The volume fraction of the compound particles in the surface layer portion including the surface 1a increases. Thus, the high-concentration compound region 2 is formed in the surface layer portion including the inner peripheral surface 1a, and a composite material in which the volume ratio of the compound particles is inclined in the thickness direction is obtained from this region.

In the above-mentioned centrifugal casting, it is also effective to use two or more kinds of compound particles having different particle diameters. Compound particles having a relatively large particle diameter tend to be concentrated on the rotation center side, and compound particles having a relatively small particle diameter are easily dispersed in a thick portion, so that the composition gradient of the compound particles can be adjusted.

The shape of the wear-resistant part 1 is preferably a cylindrical shape such as a cylinder in applying the centrifugal casting method as described above, but is not limited thereto. By processing the outer peripheral shape of the cylindrical casting, or cutting the cylindrical casting, wear-resistant parts having various shapes can be obtained. in this way,
The present invention is applicable to wear-resistant parts of various shapes.

Next, an embodiment of a casting machine part and a die casting machine according to the present invention will be described with reference to FIGS. FIG. 4 is a diagram showing a schematic configuration of a die casting machine according to an embodiment of the present invention, and FIG. 5 is an enlarged view showing a main part thereof. In these figures, reference numeral 21 denotes a movable mold 2
2 and a fixed mold 23 constitute a pair of molds, and the pair of molds 21 form a cavity 24. In the fixed mold 23, a casting port bush 25 is provided as a kind of mold so as to be connected to the cavity 24. An injection sleeve 26 is connected to the casting port bush 25, and the injection sleeve 26 is supported by a platen 27.

The injection sleeve 26 is provided with a pouring port 28 through which a light metal melt such as an Al-based metal melt is poured. A plunger tip 29 is movably disposed in the injection sleeve 26, and a plunger rod 31 driven by a plunger drive mechanism such as a hydraulic cylinder 30 is connected to the plunger tip 29. The light metal melt poured from the pouring port 28 is pressure-filled into the cavity 24 by the plunger tip 29 by operating the hydraulic cylinder 30.

The movable mold 22 is movable by a mold moving mechanism such as a hydraulic cylinder 32. When the movable mold 22 moves in a predetermined direction, the die-cast product produced in the cavity 24 is discharged from the mold by a fixed extrusion rod 33.

In the above-described die-casting machine, the inner peripheral surface 26a of the injection sleeve 26 is required to have erosion resistance because it is to be in contact with the light metal melt, and is to be polished to slide with the plunger tip 29. It is necessary to have wear properties. Thus, the inner peripheral surface 2 of the injection sleeve 26
6a is a contact surface with the molten light metal, and is also a wear-resistant surface required to have abrasion resistance, and has a roughly cylindrical shape. It is suitable as a wear-resistant part.

In this embodiment, a high-concentration compound region is formed in the surface layer including the inner peripheral surface 26a.
The injection sleeve 26 is composed of a composite material in which at least one compound particle selected from metal nitrides, metal oxides, metal borides, metal carbides and composite compounds thereof is dispersed in a metal matrix with a composition gradient. doing. The specific configuration of this composite material is the same as in the above-described embodiment of the wear-resistant component.

The compound particles concentrated on the inner peripheral surface 26a of the injection sleeve 26 and the vicinity thereof have high hardness, excellent abrasion resistance, and excellent erosion resistance as described above. Excellent abrasion resistance, erosion resistance and the like can be imparted to the inner peripheral surface 26a. Furthermore, since the compound particles have a lower thermal conductivity than a general metal material, the heat retaining property of the inner peripheral surface 26a of the injection sleeve 26 can be enhanced.

That is, the inner peripheral surface 26 of the injection sleeve 26
The high-concentration compound region formed in the surface layer portion containing a functions as a erosion barrier layer for the light metal melt, functions as a wear-resistant layer for the plunger tip 29, and further functions as a heat insulating layer. Is also provided.

As described above, based on the fact that the composition of the compound particles is inclined in the thickness direction, the high concentration compound region 2 where the compound particles are concentrated and the region where the metal matrix is dominant (the internal region) ) Can be prevented from being cracked or deformed due to the difference in thermal expansion, and embrittlement of the metal matrix mainly constituting the injection sleeve 26 can be suppressed, so that the mechanical reliability of the injection sleeve 26 is improved. After that, the wear of the injection sleeve 26 due to the light metal melt and the sliding with the plunger tip 29 can be stably suppressed over a long period of time. As a result, the life of the injection sleeve 26 can be significantly improved, and the long-term reliability of a die casting machine using the same can be improved.

The inner peripheral surface 26a of the injection sleeve 26 may be subjected to a nitriding treatment as in the case of the conventional SKD61 material. By using both the dispersion of the compound particles and the nitriding treatment, the erosion resistance can be further increased.

Here, it is preferable that the heat retaining property of the injection sleeve 26 is enhanced not only by forming the high concentration compound region but also as a whole of the injection sleeve 26. This is injection sleeve 26
This is to prevent the occurrence of problems such as entrainment of a solidification phase and obstruction of the flow of the molten metal due to solidification of the molten light metal by increasing the heat retention of the molten metal. For this reason, it is preferable to use a metal material having a thermal conductivity of 30 W / m K or less for the metal matrix forming the injection sleeve 26.
Furthermore, in order to prevent cracks due to thermal deformation of the injection sleeve 26 and galling with the plunger tip 29, the metal matrix has a thermal expansion coefficient of 15 × 10
It is preferable to use a metal material of ^-6 / K or less. More preferably, the coefficient of thermal expansion of the metal matrix is in the range of 10 to 15 × 10 ⁻⁶ / K.

An austenitic stainless steel is known as a metal material having a thermal conductivity of 30 W / m K or less. However, since the thermal expansion coefficient is as high as 18 × 10 ⁻⁶ / K, for example, Ni And at least one selected from Co and 25 to
It is preferable to use a low expansion Fe-based alloy containing about 45% by weight. Examples of such a low expansion Fe-based alloy include an invar alloy (Fe-36wt% Ni), a super-invar alloy (Fe-31wt% Ni-5wt% Co), a Kovar alloy (Fe-29wt% Ni-17wt% Co), 42 alloy (Fe
-42 wt% Ni) is also known, but low expansion cast iron is particularly preferably used in applying the above-mentioned centrifugal casting.

Specific examples of the low expansion cast iron include 0.1 to
1.0 wt% C, 3.0-7.0 wt% Si, 0.1-1.0
Low-expansion cast iron containing 0.1% by weight of Mn, 1.0% by weight or less of Mg, and 5.0 to 40% by weight of Ni, with the balance being Fe and unavoidable impurities. If necessary, C
At least one selected from the group consisting of r, Mo, W, V, Nb, Τa, Τi and Zr may be added in an amount of about 4% by weight or less.

Ni is a component imparting low thermal expansion and low thermal conductivity, and has a Ni content of less than 5.0% by weight or
If it exceeds 40% by weight, the effect of reducing the thermal expansion coefficient and the thermal conductivity cannot be sufficiently obtained. Si is a component that contributes to a reduction in oxygen concentration and an improvement in fluidity, and also imparts low thermal expansion and low thermal conductivity to the Fe-based alloy. If the Si content exceeds 7.0% by weight, a large amount of Si compounds are formed, and these characteristics are deteriorated.
% By weight or less.

C, Mn and Mg are basic components of cast iron.
C is a component that imparts castability and machinability similar to ordinary cast iron. If the content of C exceeds 1.0% by weight, the strength is reduced. Mn functions as a deoxidizing agent and a component for improving corrosion resistance. However, if the content of Mn exceeds 1.0% by weight, the coefficient of thermal expansion increases. Therefore, the content of Mn is preferably 1.0% by weight or less. Mg is a component that spheroidizes graphite.
If the content of g exceeds 1.0% by weight, low thermal expansion properties and a decrease in workability are caused.

The die-casting machine component made of a composite material in which compound particles are gradient-dispersed and dispersed in a metal matrix is not limited to the injection sleeve 26 described above, but also a casting bush having a contact surface with a light metal melt. 2
5. It is also effective for the mold 21. Further, the casting machine component of the present invention is not limited to the die casting machine component as described above, but can be applied to, for example, a stalk for low pressure casting. In particular, it is suitable for a casting machine part in which the cylindrical inner peripheral surface is a contact surface with the molten metal.

[0049]

Next, specific examples of the present invention will be described.

Example 1 An Fe-based alloy (low expansion cast iron) having a composition shown in Table 1 was used.
Melting was performed in a high frequency melting furnace. Thermal conductivity K of this Fe-based alloy
Is about 25 W / m K and the coefficient of thermal expansion from room temperature to 623 K is 11 × 10 ⁻⁶ / K.

[0051]

[Table 1] 5% by volume alumina particles are put into the Fe-based alloy melt as described above to form a composite material melt, and the injection having the shape as shown in FIG. 5 is performed using the centrifugal casting apparatus shown in FIG. A sleeve was made. The casting dimensions of the injection sleeve were 105 mm outside diameter, 45 mm inside diameter, and 360 mm length, and the dimensions after processing were 100 mm outside diameter, 60 mm inside diameter, and 350 mm length. As the alumina particles, those obtained by mixing two types of particles having an average particle diameter of 100 μm and 240 μm by 50% were used. A sand mold corresponding to the shape of the injection sleeve was attached to the centrifugal casting device.

Specifically, first, 5% by volume based on the amount of molten metal
Alumina particles of about 1823K into a tribe containing molten Fe-base alloy and stirred, immediately from the tribe to 1000rpm
The casting was performed through the pouring pan of the centrifugal casting machine rotating at. After rotating for about 10 minutes, the casting was removed from the sand mold. After grinding and removing the inner diameter of the casting by about 15 mm, a stress relief annealing heat treatment was performed at 923 K to finish to a final shape.

FIG. 6 shows the change in the volume ratio of alumina particles in the thickness direction from the inner peripheral surface of the injection sleeve thus obtained. The injection sleeve was assembled into a die-casting machine, and a mounting test was performed (die-casting test of molten Al alloy), and the erosion resistance of the injection sleeve was evaluated by examining a change in wall thickness immediately below the pouring port. Specifically, the number of shots in which the wall thickness immediately below the pouring gate was reduced by 1 mm was measured. Further, the openings at both ends of the injection sleeve were closed with bricks, and a molten metal of 953K Al alloy (ADC12) was poured at a filling rate of 20%, and the solidification time of the Al alloy at this time was measured. Table 2 shows the results.

Examples 2 to 5 In the same manner as in Example 1, except that the compound particles to be charged into the Fe-based alloy melt serving as the metal matrix were changed to the respective compound particles shown in Table 2, the injection sleeves were respectively used. Was prepared. Each compound particle has a particle size of 100 μm and 2
A mixture of 50 to 320 μm in 50% increments was added at 5 to 7% by volume based on the molten metal. Using each of these injection sleeves, erosion resistance and heat retention were measured and evaluated in the same manner as in Example 1. Table 2 also shows these results.

In the fifth embodiment, the inner peripheral surface of the injection sleeve of the first embodiment is further subjected to a nitriding treatment. The gas nitriding was performed under the conditions of 823K × 40 hours.

[Table 2] As is clear from Table 2, it can be seen that the injection sleeves according to the examples are all excellent in erosion resistance and heat retention. In addition, in the injection sleeve of each example, galling or the like was not generated by the plunger tip during the mounting test of the Al alloy, and it was confirmed that the injection sleeve was excellent in abrasion resistance.

[0056]

As described above, according to the abrasion-resistant part and the casting machine part of the present invention, even when the abrasion-resistant part is used under severe conditions such as contact with the molten metal, the abrasion-resistant part can be used. Properties and erosion resistance can be stably maintained over a long period of time. Therefore, it is possible to greatly improve the reliability of a die casting machine or the like using the same. Further, according to the method for manufacturing a wear-resistant component of the present invention, such a component can be easily and reproducibly manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a configuration of an embodiment of a wear-resistant component of the present invention.

FIG. 2 is a view for explaining a dispersion state of compound particles of the wear-resistant part shown in FIG.

FIG. 3 is a cross-sectional view showing one configuration example of a centrifugal casting device used for manufacturing a wear-resistant part of the present invention.

FIG. 4 is a view showing a schematic cross section of a schematic configuration of an embodiment of the die casting machine of the present invention.

5 is an enlarged view showing a main part of the die casting machine shown in FIG. 4;

FIG. 6 is a view showing a result of measuring a dispersion state of compound particles in an injection sleeve according to Example 1 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Abrasion-resistant parts 1a ... Inner peripheral surface 2 ... High-concentration compound area 11 ... Centrifugal casting device 21 ... A pair of molds 26 ... Injection sleeve

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masato Yada 2121 Nao, Asahi-machi, Mie-gun, Mie Prefecture Inside Mie Plant of Toshiba Corporation

Claims (8)

[Claims] 1. It has a wear-resistant surface where abrasion resistance is required,
A wear-resistant part comprising a composite material in which at least one compound particle selected from a metal nitride, a metal oxide, a metal boride, a metal carbide and a composite compound thereof is dispersed in a metal matrix. The abrasion resistance is characterized in that the compound particles have a composition gradient from the abrasion-resistant surface in a thickness direction of the component such that a volume ratio of the compound particles in the metal matrix decreases. Sex parts. 2. The wear-resistant part according to claim 1, wherein the part has a cylindrical shape, and an inner peripheral surface of the cylindrical part is the wear-resistant surface. And wear-resistant parts. 3. When manufacturing a wear-resistant part having a cylindrical shape and having an abrasion-resistant surface required to have abrasion resistance on its inner peripheral surface side, a metal matrix mainly constituting said part. In the molten metal, at least one selected from metal nitrides, metal oxides, metal borides, metal carbides and composite compounds thereof
A step of feeding one kind of compound particles to prepare a composite material melt; and a step of using the composite material melt to produce the cylindrical component by centrifugal casting. Manufacturing method of wearable parts. 4. A metal matrix having a contact surface with a molten metal, wherein at least one compound particle selected from a metal nitride, a metal oxide, a metal boride, a metal carbide, and a composite compound thereof is contained in a metal matrix. A casting machine part made of a dispersed composite material, wherein the compound particles have a reduced volume fraction of the compound particles in the metal matrix in a thickness direction of the part from a contact surface with the molten metal. A component for a casting machine characterized by having a composition gradient. 5. The casting machine component according to claim 4, wherein the component has a cylindrical shape, and an inner peripheral surface of the cylindrical component is a contact surface with the molten metal. Characterized wear-resistant parts. 6. The casting machine part according to claim 4, wherein said metal matrix is made of a metal material having a thermal conductivity of 30 W / m K or less. 7. The part for a casting machine according to claim 4, wherein said metal matrix is made of a metal material having a thermal expansion coefficient of 15 × 10 ⁻⁶ / K or less. 8. A pair of molds, one of which is movable, an injection sleeve connected to a fixed mold of the pair of molds and serving also as a pouring receiver and a pressure cylinder, and In a die casting machine including a plunger for pressure-filling the poured molten metal into the pair of dies, and a driving mechanism for the plunger, at least one selected from the pair of dies and the injection sleeve may be configured as follows. Item 6. A die casting machine comprising the casting machine part according to Item 4.