JP6722764B2 - Die casting sleeve and manufacturing method thereof - Google Patents

Description

The present invention relates to a die casting sleeve that is a component of a die casting apparatus and a method for manufacturing the sleeve.

A die casting sleeve, which is one of the components of a die casting apparatus used for die casting, is generally cylindrical. On the side surface of the cylindrical die casting sleeve, a molten metal supply port for supplying the molten metal to the internal flow path is provided. Then, when the die casting apparatus is in operation, for example, a metal melt such as aluminum, aluminum alloy, zinc or zinc alloy is supplied into the cylinder from the above-mentioned melt supply port. The supplied molten metal is injected from the molten metal injection port toward the mold cavity by the plunger. As a material for such a die-casting sleeve, for example, SKD61, which is a standard steel type of “alloy tool steel material” of JIS-G-4404:2006, is often applied. Further, there has been proposed a die casting sleeve in which a surface treatment such as a nitriding treatment is performed on the inner surface of the die casting sleeve made of SKD61 or the like (Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 2005-205666 Japanese Patent Laid-Open No. 2012-219340

One of the important properties required for die casting sleeves is melting resistance. Melting loss is the wear of the sleeve material caused by the molten metal coming into contact with the inner surface of the die casting sleeve. If this wear is severe, an injection abnormality or the like will occur during casting, and the life of the die casting sleeve will be shortened. When the inner surface of the die casting sleeve is subjected to a surface treatment, an effect of improving the melt damage resistance is recognized to some extent, but further improvement of the melt damage resistance has been demanded.
An object of the present invention is to provide a die-casting sleeve excellent in melting resistance and a manufacturing method thereof.

According to an aspect of the present disclosure,
A sleeve for die casting having a flow path inside,
A molten metal supply port for supplying a molten metal to the flow path from the outside penetrates from the inner surface to the outer surface of the sleeve for die casting,
At least a portion of the inner surface forming the flow path facing the molten metal supply port has a mass% of C: 0.4% or more and 2.5% or less, Si: 1.0% or less, Mn: 1.0% or less. , Cr: 3.0% or more and 12.0% or less, and a die casting sleeve made of a material having a composition of the balance Fe and impurities.

Further, according to an aspect of the present disclosure,
A method of manufacturing a die casting sleeve having a flow path inside, a melt supply port for supplying a metal melt from the outside to the flow path, which penetrates from an outer surface to an inner surface,
Prepare a spare body that will be the sleeve for die casting,
At least a portion of the inner surface forming the flow path that faces the molten metal supply port or a portion that faces the molten metal supply port has C: 0.4% or more and 2.5% or less, Si: 1% by mass. Provided is a method for producing a die casting sleeve, which comprises providing a material having a composition of 0.0% or less, Mn: 1.0% or less, Cr: 3.0% or more and 12.0% or less, and the balance Fe and impurities.

According to the present invention, there is provided a die casting sleeve having excellent melt resistance and a method for manufacturing the same.

It is a schematic diagram which shows the cross-section of the sleeve for die casting of this invention. It is a schematic diagram which shows the cross-section of another die casting sleeve of this invention. It is a drawing substitute photograph which shows the external appearance of the die casting sleeve used in the Example. It is a drawing substitute photograph which shows the inner surface of the position where the molten metal supply port of the sleeve for die castings of the present invention example after die casting is provided. It is a drawing substitute photograph which shows the inner surface of the position for which the molten metal supply port of the sleeve for die castings of a comparative example was provided after die casting. It is a drawing substitute photograph which shows the inner surface of the position where the molten metal supply port of the sleeve for die castings of the present invention example after die casting is provided. It is a drawing substitute photograph which shows the inner surface of the position for which the molten metal supply port of the sleeve for die castings of a comparative example was provided after die casting. It is a figure which shows the shape of the test piece used in the melting test of an Example. It is a figure explaining the point of the melting test of an example.

The present inventor investigated the state of melting damage occurring on the inner surface of the die casting sleeve. As a result, it has been found that the above-mentioned melting loss is remarkable in the inner surface of the die-casting sleeve, particularly at the portion facing the molten metal supply port. Therefore, it has been found that the melting resistance of the die casting sleeve as a whole can be improved by reviewing at least the material forming this portion, and the present invention has been completed.

In addition, the above-mentioned "cylindrical shape" means a shape in which a cavity as a flow path is formed inside, such as a cylindrical shape or a rectangular tube shape. The die casting sleeve may have a shape in which a cylindrical portion and a rectangular tubular portion are combined. The sleeve for die casting may be provided with protrusions or flanges on the outer peripheral surface of the cylindrical body.

The shape of the flow path may be cylindrical, prismatic, or a combination thereof. A cylindrical flow path may be formed in the cylindrical die casting sleeve. Alternatively, a prismatic channel may be formed in a cylindrical sleeve for die casting.

The molten metal supply port is provided on the outer peripheral surface of the cylindrical die casting sleeve. The die casting sleeve is used in a posture in which the molten metal supply port opens upward and the flow path extends substantially in the horizontal direction.

By the way, the melt loss includes “physical melt loss” caused by impact energy caused by falling of the metal melt and “chemical melt loss” caused by a chemical reaction with the metal melt. As a result of the investigation, it was found that physical erosion greatly affects the erosion resistance at the portion of the inner surface forming the flow path facing the molten metal supply port. At this portion, the metal melt supplied from the melt supply port to the flow path hits “with force”, so that remarkable physical melting loss is likely to occur.

A die casting sleeve has been proposed in which a surface treatment layer having a low chemical reactivity with a molten metal is provided on a material. This surface treatment layer is provided for the purpose of preventing the material forming the die casting sleeve and the molten metal from directly contacting each other, and has a certain effect on chemical erosion. However, the strength of the surface treatment layer is limited with respect to physical melt loss caused by mechanical factors of the molten metal, and the effect of limiting physical melt loss is limited only by the surface treatment layer.

In addition, in the recent die-cast casting, as the quality of the die-cast products produced increases, the number of castings under special conditions is increasing.
For example, in the case of general aluminum die casting, ADC12 (Fe: 1.3 mass% or less) specified in "Aluminum alloy die casting" of JIS-H-5302:2006 is used as a casting material, and at the time of casting The temperature of the molten metal is 660 to 680°C. Some automobile parts are changed from iron to aluminum alloy in order to reduce the weight. Such modifications may compensate for die cast product strength which is reduced with the change from iron to aluminum alloys.

In order to compensate for this strength, it is effective to suppress the occurrence of "cavity" in the die cast product. Therefore, a method of improving the flowability of the molten metal by increasing the temperature of the molten metal of the aluminum alloy is often used. Then, when the temperature of the molten metal rises to a special level of “700° C. or higher”, chemical erosion between the molten metal and the inner surface of the die casting sleeve is accelerated.
Further, for the above-mentioned strength compensation, a method of improving the strength of the die cast product by reducing the amount of Fe in the aluminum alloy is often used. Then, in the case of a special aluminum alloy in which the Fe content is reduced to the level of "0%", chemical erosion is accelerated.
In such special die casting, even the conventional die casting sleeve having the surface treatment layer has a limited effect of suppressing chemical erosion.

As described above, the present inventor has been able to reduce the physical melt loss in the portion of the inner surface forming the flow path facing the molten metal supply port, and to reduce the chemical melt loss in recent special die casting. We found that there is room for improvement.

Therefore, the present inventor firstly, a material for a sleeve for die casting (hereinafter, simply referred to as a “sleeve material”) that is resistant to a physical impact when the molten metal is supplied and has a low chemical reactivity with the molten metal. As a result, this sleeve material was found to have a content of “% by mass: C: 0.4% or more and 2.5% or less, Si: 1.0% or less, Mn: 1.0% or less, Cr: 3 It has been found that "a material having a compositional composition of Fe and impurities of 0.0% or more and 12.0% or less" is effective. The above component composition will be described below.

C: 0.4% by mass or more and 2.5% by mass or less (hereinafter, simply referred to as "%" by mass%)
C is an element that combines with Cr, W, Mo, V, and Nb to form a carbide, which improves the wear resistance of the die casting sleeve. The improvement in wear resistance is effective in suppressing physical melt loss. However, if the amount is too large, the toughness decreases. Therefore, it should be 0.4% or more and 2.5% or less after being balanced with the contents of Cr, W, Mo, V and Nb described later.
In addition, C is preferably 0.4% or more and less than 1.0%. If the C content is within this range, it is easy to achieve both the toughness of the sleeve material and the high temperature strength. More preferably, C is 0.9% or less. And, even more preferably, C is 0.8% or less, and particularly preferably, C is 0.6% or less. Further, C is more preferably more than 0.42%. And, C is more preferably 0.43% or more, and particularly preferably C is 0.44% or more.
Alternatively, C is preferably 1.0% or more and 2.5% or less, and in this case, the sleeve material is preferably a sintered material obtained by sintering a powder material. The sintered material is preferably obtained by sintering a metal powder having the same composition as the sleeve material to be obtained. At the time of sintering, it is preferable to use HIP (hot isostatic pressing) treatment. Generally, when the content of C is high, the high temperature strength of the raw material is high, but the carbide tends to be coarse or segregate easily, and the toughness tends to be low. However, by sintering the metal powder, it is easy to form carbides in the structure finely and uniformly, and further it is easy to make the structure itself finer, so that the toughness of the material is easily increased. More preferably, C is 1.2% or more. More preferably, C is 1.5% or more. Even more preferably, C is 1.7% or more. Further, C is more preferably 2.3% or less.

-Si: 1.0% or less Si is usually used as a deoxidizing agent in the melting step. And, it has an effect of enhancing the machinability of the sleeve material. However, if the amount is too large, the toughness of the sleeve material decreases. Therefore, Si is 1.0% or less. It is preferably 0.6% or less. It is more preferably 0.5% or less. Further, the lower limit of Si is not particularly defined (though it may be 0%), but it is preferably more than 0%. The amount of Si is more preferably 0.1% or more.

-Mn: 1.0% or less Mn, like Si, is used as a deoxidizing agent. Then, it has an effect of enhancing the hardenability and imparting an appropriate quenching and tempering hardness to the die casting sleeve. However, if the amount is too large, the retained austenite increases in the structure after quenching and tempering, and the toughness decreases. Therefore, Mn is set to 1.0% or less. It is preferably 0.7% or less. It is more preferably 0.6% or less. Further, the lower limit of Mn is not particularly specified (though it may be 0%), but it is preferably more than 0%. The Mn content is more preferably 0.1% or more. More preferably, it is 0.2% or more.

-Cr: 3.0% or more and 12.0% or less Cr is an element effective for improving hardenability and forming carbides and improving wear resistance of the sleeve material. The improvement in wear resistance is effective in suppressing physical melt loss. Further, since Cr has a melting point of about 1903° C., which is higher than the melting point of Fe (about 1539° C.) and is an element that makes it difficult to react with the molten metal, Cr is also effective in suppressing chemical erosion. Element. However, if it is too large, the toughness and the high temperature strength are deteriorated. Therefore, Cr is 3.0% or more and 12.0% or less. It is preferably 3.5% or more. It is more preferably 4.0% or more. Further, it is preferably 11.0% or less.
In addition, in the relationship between the characteristics of the toughness required for the die casting sleeve and the melting resistance, when the melting resistance is important, Cr is preferably 7.0% or more. It is more preferably 8.0% or more, and particularly preferably 9.0% or more. Further, when the toughness is important, Cr is preferably less than 7.0%. It is more preferably 6.0% or less, and particularly preferably 5.0% or less.

The sleeve material described above may contain one or more elements of Mo and W in addition to the above-mentioned elemental species. Mo is preferably less than 1.0% or 1.6% or more and 15.0% or less in the relational expression of (Mo+1/2W). The fact that Mo is specified to be less than 1.0% is based on the assumption that Mo is contained as an impurity in the sleeve material, and the sleeve material does not actively contain Mo. Mo itself is a relatively expensive material. Further, if Mo is mixed in the material, the mechanical strength of the material becomes high, and thus the workability of the material becomes high. Therefore, a sleeve material having a Mo content of less than 1.0% in which Mo is not positively mixed can be provided at a relatively low cost, and the processing difficulty is not high, which is preferable. In this case, Mo is more preferably 0.5% or less, further preferably 0.3% or less, still more preferably 0.15% or less. Then, the lower limit of Mo can be set to 0%.

Mo, W: (Mo+1/2W) relational expression: 1.6% or more and 15.0% or less Mo and W combine with C to form a carbide, which imparts wear resistance to the die casting sleeve. , Is an element that suppresses physical melt loss. Further, Mo has a melting point of about 2620° C. and W has a melting point of about 3380° C., which is higher than the melting point of Fe, and Mo and W are effective elements for suppressing chemical erosion. It is an element that has a large secondary hardening effect during tempering and can also impart high-temperature strength. However, if the amount is too large, machinability and toughness are deteriorated.
Mo and W may be contained alone or in combination as required. Since the content of W at this time is about twice the atomic weight of Mo, the content can be specified together with the “Mo equivalent” defined by the relational expression of (Mo+1/2W). Further, in the present invention, when at least one of Mo and W is contained, it is necessary to contain 1.6% or more in the above relational expression. It is more preferably 2.0% or more. It is particularly preferably 2.5% or more. And, at least one of Mo and W can contain 15.0% or less in the value by the relational expression of (Mo+1/2W). It is preferably 10.0% or less. It is more preferably 5.0% or less. And when it is desired to emphasize the toughness, etc., it is particularly preferably 3.0% or less.
In addition, it is also preferable to contain Mo: 1.0% or more and 1/2 W: 0.6% or more for each element of Mo and W.

The sleeve material described above may contain V in addition to the elemental species described above.
-V: 6.0% or less V is an element that combines with C to form a hard carbide, contributes to the improvement of the wear resistance of the die casting sleeve, and suppresses physical melt loss. The melting point of V is about 1847° C., which is higher than the melting point of Fe, and is an element that effectively acts to suppress chemical erosion. However, if the amount is too large, the toughness decreases. Therefore, V can contain 6.0% or less, if necessary. It is preferably 4.0% or less. It is more preferably 3.0% or less. More preferably, it is 2.0% or less. Further, when V is contained, it is preferably 0.5% or more. It is more preferably 1.0% or more. More preferably, it is 1.1% or more. It is particularly preferably more than 1.2%.

Further, the sleeve material described above may include one or more elements of Co and Nb in addition to the above-mentioned elemental species.
Co: 10.0% or less Co is an element that forms a solid solution in the matrix and improves the strength and heat resistance of the sleeve material. However, if it is too large, the toughness is reduced. Therefore, in the present invention, 10.0% or less of Co can be contained, if necessary. It is preferably 5.0% or less. It is more preferably 3.0% or less. It is particularly preferably 2.0% or less. Further, the lower limit of Co is not particularly specified (though it may be 0%), but it can be 0% or more. When Co is contained, it is preferably 0.5% or more.

-Nb: 3.0% or less Nb is an element that forms a carbide to strengthen the matrix of the sleeve material and improve wear resistance. It also has a high melting point of about 2415° C. and is an element that works to suppress chemical erosion. However, if the amount is too large, the machinability of the sleeve material is deteriorated. Therefore, Nb can contain 3.0% or less, if necessary. It is preferably 2.0% or less. It is more preferably 1.0% or less. Further, the lower limit of Nb is not particularly specified (though it may be 0%), but it can be 0% or more. When Nb is contained, the above effect can be obtained by containing 0.01% or more.

P, S, Ni, Cu, Al, Ca, Mg, O (oxygen), and N (nitrogen) are elements that may remain in the material as impurities. In the present invention, it is preferable that these elements are as low as possible. However, on the other hand, a small amount may be contained in order to obtain additional operational effects such as morphology control of inclusions, other mechanical properties, and improvement of manufacturing efficiency. In this case, 0≦P≦0.05%, 0≦S≦0.05%, 0≦Ni≦1.0%, 0≦Cu≦0.3%, 0≦Al≦0.3%, 0≦ A range of Ca≦0.02%, 0≦Mg≦0.02%, 0≦O≦0.03%, and 0≦N≦0.05% is sufficiently acceptable.

Among the die-casting sleeves, the sleeve material having the above component composition constitutes "at least the portion of the inner surface forming the flow path that faces the molten metal supply port", and the physics that occurs remarkably at the portion that faces the molten metal supply port. Melt loss can be suppressed. Further, since the composition is effective for suppressing chemical erosion, the erosion resistance of the die casting sleeve as a whole can be improved.

FIG. 1 is a schematic diagram of a die casting sleeve 1. As shown in FIG. 1, the die casting sleeve 1 has a molten metal supply port 2 that opens upward, a molten metal discharge port 6 that opens leftward, and a plunger insertion port 8 that opens rightward. A flow path 7 is provided inside the die casting sleeve 1. A molten metal supply port 2 for supplying a molten metal to the flow path 7 from the outside penetrates from the inner surface to the outer surface of the die casting sleeve 1. The molten metal supplied to the flow path 7 from the outside through the molten metal supply port 2 is pushed by a plunger (not shown) inserted from the plunger insertion port 8 to the outside (mold cavity) from the molten metal discharge port 6. Is emitted.

An example of a method of manufacturing such a die casting sleeve 1 will be described with reference to FIG.
First, the spare body 3 is prepared. In the present embodiment, the preparatory body 3 is a tubular member. A part of the inner surface of the preliminary body 3 forms a part of the flow path 7. On a part of the inner surface of the preparatory body 3, an enlarged diameter portion 3a having a diameter larger than that of the flow path 7 is provided. A first opening 3b forming a part of the molten metal supply port 2 is provided on the side surface of the preparatory body 3.

Next, the tubular member 5 is arranged in the expanded diameter portion 3a. The outer diameter of this member 5 is the same as or slightly larger than the inner diameter of the expanded diameter portion 3a. The inner surface of the member 5 forms the flow path 7. The member 5 is provided with a second opening 5a that forms the molten metal supply port 2 together with the first opening 3b. At least a portion 4 of the inner surface of the member 5 facing the second opening 5a is formed of a sleeve material having the above-described composition. In the present embodiment, the entire member 5 is formed of the sleeve material having the above component composition. By thus combining the preparatory body 3 and the member 5, the die casting sleeve 1 in which the portion 4 facing the molten metal supply port 2 is made of the raw material having the above-mentioned component composition can be manufactured.

Thereafter, if necessary, a part or the whole of the die casting sleeve 1 may be subjected to heat treatment (quenching and tempering) to adjust to a predetermined hardness.

In addition, in the above-mentioned embodiment, the example which forms the molten metal supply port 2 by combining the preliminary|backup body 3 which has the 1st opening 3b, and the member 5 which has the 2nd opening 5a was demonstrated, but this invention is this. Not limited to After the preliminary body 3 having no first opening and the member 5 having no second opening are combined with each other, a through hole penetrating from the outside to the inside is formed in the preliminary body 3 and the member 5 so that the molten metal supply port 2 is formed. It may be formed. In other words, the sleeve material (member 5) having the above-described composition may be provided in the "region facing the molten metal supply port" with respect to the preform 3 after the molten metal supply port 2 is provided. However, the sleeve material (member 5) having the above-described composition is provided in the "region facing the portion serving as the molten metal supply port" with respect to the preparatory body 3 before the molten metal supply port 2 is provided. Good.

The member 5 having the above-described component composition can be a cast material or a sintered material produced by a powder metallurgy method. Then, in addition to disposing the member 5 having the above-mentioned component composition on the preliminary body 3, for example, a material having the above-mentioned component composition is lined by a technique such as overlay welding or thermal spraying, or a ring having the above-mentioned component composition. The shaped part (inner sleeve) may be shrink-fitted. In the case of the shrink fitting method, compressive stress can be applied to the ring-shaped component, so that cracking of the ring-shaped component can be suppressed.

In particular, when the sleeve material having the above-mentioned component composition is a “preformed article before being provided” such as a tubular member or a ring-shaped member, the preliminary body 3 and the member 5 are arranged before the member 5 is arranged. And can be heat treated separately. As a result, the hardness of each part of the die casting sleeve 1 can be adjusted to a desired hardness.

For example, while adjusting the preliminary body 3 (that is, the inner surface of the flow path 7 excluding the inner surface of the member 5 in the case of FIG. 1) to a hardness of 40 to 48 HRC which emphasizes toughness, the member 5 is adjusted to 50 HRC or more. It is effective to improve the life of the die casting sleeve 1 as a whole by adjusting the hardness so as to emphasize the melting resistance.
For example, it is preferable to adjust the hardness of the member 5 in the range of 50 to 75 HRC. By increasing the hardness of the member 5, the compressive strength of the member 5 is improved and the resistance to physical melting damage is improved. It is also considered that the carbides in the metallographic structure of the member 5 are enriched and the distribution thereof becomes uniform with the above heat treatment, which contributes to the improvement of resistance to physical melt damage. That is, the harder the member 5, the better the resistance to physical melt damage, which is preferable.

In order to harden the member 5, it is effective to increase the C content of the member 5, and for example, the C content is preferably 1.0% or more. However, in the case of the member 5 having such a composition, coarse carbides are likely to be formed in the structure, and there is a concern that the toughness may decrease. Therefore, the member 5 having a C content of 1.0% or more is preferably, for example, the above-mentioned “sintered material”. As a result, the carbide in the structure of the member 5 can be made fine and uniform, and further, the structure itself can be made fine, which is advantageous for maintaining and improving excellent toughness. In this case, sufficient toughness can be ensured even if the member 5 is adjusted to have a hardness of "exceeding 60 HRC", or actually adjusted to a hardness of about 75 HRC.

As an example of the composition in which the content of C is 1.0% or more, for example, C: 1.0% or more and 2.5% or less, Si: 1.0% or less, Mn: 1.0% or less, Cr: 3.0% or more and 12.0% or less, one or two kinds of Mo and W according to the relational expression (Mo+1/2W): 10.0% or more and 15.0% or less, V: 3.0 % And 6.0% or less, and the component composition of the balance Fe and impurities can be set. Further, this component composition can further contain at least one of Co and Nb in an amount of Co: 10.0% or less and Nb: 3.0% or less.

As described above, when the C content is 1.0% or more, the hardness of the member 5 is easily increased, which is preferable. However, when the content of C is less than 1.0%, it is effective from the viewpoint of suppressing cracking of the member 5 due to thermal shock and economical efficiency as described in detail below, and the content of C is 1.0%. It is also preferably less than.
In consideration of suppressing cracking of the member 5 due to thermal shock, the hardness of the member 5 is preferably "60 HRC or less". It is more preferably 58 HRC or less, still more preferably less than 55 HRC, and even more preferably less than 54 HRC. In the case of the member 5 having such hardness, for example, the content of C can be set to less than 1.0%. As a result, excellent toughness can be secured even if the member 5 is made of a cast material (without being made of a sintered material). As a composition having a C content of less than 1.0%, for example, C: 0.4% or more and less than 1.0%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 3.0. % Or more and less than 7.0%, one or two kinds of Mo and W according to the relational expression of (Mo+1/2W): 1.6% or more and 15.0% or less, V: 0.5% or more and 6.0 % Or less, and the compositional composition of the balance Fe and impurities is preferable. Further, this component composition can further contain at least one of Co and Nb in an amount of Co: 10.0% or less and Nb: 3.0% or less.
The member 5 having C less than 1.0% may of course be a sintered material.

On the other hand, in the case where the member 5 is an “article formed after being provided” such as a welding material or a thermal spray material, as described above, a part or the whole of the die casting sleeve 1 after the member 5 is arranged is heat treated. Become. In the case where the entire die casting sleeve 1 is heat-treated "simultaneously", the materials (components) that can achieve a desired balance between hardness and toughness under common heat treatment conditions in both the preform 3 and the member 5. It is effective to select the composition. Alternatively, it is possible to select the optimum heat treatment condition for either the preparatory body 3 or the member 5. At this time, depending on the target hardness (heat treatment condition) of the member 5, the above-mentioned composition of the content of C is 1.0% or more, or the content of C is 1. It is also possible to apply any of the compositions below 0%. In addition, in the case of the method of applying the welding material or the thermal spray material to the member 5, the risk that the member 5 after the placement is displaced or dislocated from the inner surface of the preliminary body 3 is reduced.

According to the above-mentioned manufacturing method, the portion (preliminary body 3) that does not require special measures against melting damage can be manufactured with a general-purpose/inexpensive material such as SKD61, which is advantageous in reducing the labor and cost required for manufacturing. Is. In addition, since it is possible to separately manufacture a portion that requires measures against melting damage and a portion that does not require measures, it is possible to adjust optimal mechanical characteristics (for example, hardness) at each portion. That is, the die casting sleeve of the present invention is preferably made of a material (sleeve material) having at least a portion of the inner surface forming the flow path facing the molten metal supply port and having the above-described component composition. The inner surface other than the portion facing to is composed of "another material" having a component composition different from that of the above-mentioned sleeve material.

The above-mentioned "at least the portion facing the molten metal supply port" is, for example, on the cylindrical inner surface forming the flow path, "a portion of the entire circumference from the portion facing the molten metal supply port to the portion of the molten metal supply port (for example, 1) of the member 5 of FIG. 1). Further, the above-mentioned "at least the portion facing the molten metal supply port" faces the molten metal supply port with respect to the total length of the flow path (the length from the plunger insertion port 8 to the molten metal discharge port 6 in FIG. 1), for example. The length including the portion may be “up to half of the total length (for example, the entire inner surface of the member 5 in FIG. 1)”.

The composition of the "other material" is, for example, by mass%, C: 0.30% or more and 0.50% or less, Si: 1.5% or less, Mn: 1.0% or less, Cr. : 4.0% or more and 6.0% or less, one or two kinds of Mo and W according to the relational expression of (Mo+1/2W): 0.8% or more and less than 1.6%, V: 0.3% It is possible to be not less than 1.5%, Co: not less than 0% and not more than 1.0%, Nb: not less than 0% and not more than 0.3%, and balance Fe and impurities. P, S, Ni, Cu, Al, Ca, Mg, O (oxygen), and N (nitrogen) are elements that may remain in the material as impurities. And 0≦P≦0.05%, 0≦S≦0.05%, 0≦Ni≦1.0%, 0≦Cu≦0.3%, 0≦Al≦0.3%, 0≦Ca A range of ≦0.02%, 0≦Mg≦0.02%, 0≦O≦0.03%, and 0≦N≦0.05% is sufficiently acceptable.
In the case of SKD61, in mass%, C: 0.35% or more and 0.42% or less, Si: 0.80% or more and 1.20% or less, Mn: 0.25% or more and 0.50% or less, P:0. 0.030% or less, S: 0.020% or less, Cr: 4.80% or more and 5.50% or less, Mo: 1.00% or more and 1.50% or less, V: 0.80% or more and 1.15%. Below, the balance is Fe and impurities.

It should be noted that at least the portion of the inner surface forming the flow path 7 other than the portion 4 facing the molten metal supply port 2 may be formed of the sleeve material having the above-described component composition. For example, as shown in FIG. 2, all the inner surfaces forming the flow path 7 of the die casting sleeve 1 may be composed of the member 51 having the above-mentioned component composition. Alternatively, the entire die-casting sleeve can be made of a sleeve material having the above component composition. Then, a part or the whole of this die casting sleeve may be heat-treated to adjust it to a predetermined hardness. The above-mentioned thing can be applied about the point of this heat treatment.

After the member 5 having the above-described component composition is provided on the die casting sleeve 1, the surface of the member 5 may be finished into a product shape by finishing machining or the like, if necessary.
The member 5 preferably has a thickness of 2 mm or more in the state of being incorporated in the preliminary body 3. It is more preferably 4 mm or more, further preferably 7 mm or more, and particularly preferably 10 mm or more. If the member 5 is a “member preformed before being provided” such as a tubular member or a ring-shaped member, such a thickness may be adjusted by greatly adjusting the thickness of the ring-shaped article. Alternatively, in the case of an "article formed after being provided" such as a welding material or a thermal spray material, "multilayer deposition" may be performed during the overlay welding or thermal spraying.

In the die casting sleeve 1 of the present embodiment, the surface of the member 5 forming the flow path 7 may be surface-treated. That is, the surface treatment layer 5b may be provided on the surface of the member 5 forming the flow path 7.
In addition to nitriding treatment, the type of surface treatment can be appropriately selected from homo-treatment, physical vapor deposition method, chemical vapor deposition method and the like. As the type of the surface treatment layer 5b, in particular, a nitride layer such as a nitride layer or a nitrogen diffusion layer, an oxide layer, an oxynitride layer, a sulfuritride nitride layer mainly composed of sulfide and nitride, etc. Is effective in suppressing chemical erosion. These surface treatment layers may be used in combination. The thickness of the surface treatment layer is preferably 0.2 mm or more and 0.5 mm or less.

As an example of the surface treatment layer 5b described above, a layer having a "nitride layer" and an "oxide layer" on the nitride layer is preferable.
The thickness of the nitride layer is more preferably larger than 0 mm and 0.2 mm or more. Further, it is more preferable to set it to 0.4 mm or less. Such a nitriding layer can be formed by various known nitriding treatments such as gas soft nitriding treatment.
Further, the oxide layer is more preferably a “magnetite layer”. The thickness of the oxide layer is more preferably larger than 0 mm and 0.001 mm or more. Further, it is more preferable to set it to 0.02 mm or less. Such an oxide layer can be formed, for example, by a known homo treatment, steam treatment, or the like.

The surface treatment layer 5b described above is effective in suppressing chemical erosion. Even if the molten metal that is vigorously supplied from the molten metal supply port 2 to the flow path 7 destroys the surface treatment layer 5b, the member 5 having the above-described component composition, which is present underneath, has the effect of further promoting the progress of melting loss. To suppress. Therefore, by providing the above-mentioned member 5 on the portion 4 of the inner surface forming the flow path 7 facing the molten metal supply port 2 and further providing the surface treatment layer 5b on the member 5, the melting resistance of the die casting sleeve 1 as a whole is improved. Further improve.

The surface treatment layer 5b may extend to the inner surface of the flow path 7 other than the portion 4 facing the molten metal supply port 2. For example, the surface treatment layer 5b may be provided on the part forming the melt supply port 2, the part forming the melt outlet 6, or the entire inner surface forming the flow path 7. On the inner surface of the inner surface forming the flow path 7 other than the portion 4 facing the molten metal supply port 2, the degree of occurrence of physical erosion is low, so that the surface treatment layer 5b excellent in the ability to suppress chemical erosion is formed. Contributes to the overall improvement of melting resistance.

In the above description, the part facing the melt supply port means at least a part that is visible when the inner surface of the die casting sleeve is seen from the opening direction of the melt supply port 2. The die-casting sleeve is generally incorporated in a die-casting device in a posture in which the opening direction of the molten metal supply port extends substantially vertically downward. Therefore, it is preferable to provide the sleeve material of the present invention, which is resistant to physical and chemical erosion, at a portion facing the molten metal supply port.

Then, in die casting, the molten metal supplied from the molten metal supply port of the die casting sleeve may collide with a portion located at approximately 45° with respect to the above-described vertically downward direction. For this reason, it is preferable to provide the sleeve material of the present invention also in the portion located at 45°. Even in this case, since the molten metal that collides with the above-mentioned portion located at 45° flows toward the portion facing the molten metal supply port, the facing portion may also be melted. For this reason, when the sleeve material is provided at the portion facing the molten metal supply port, melting loss can be reduced.

<Production of sleeve for die casting>
Cylindrical die-casting sleeve preparatory bodies A1 and B1 each having an outer diameter of 200 mm, an inner diameter of 85 mm, and a length of 550 mm were prepared. The material of the die casting sleeve preforms A1 and B1 is SKD61.

-Production of Sleeve A for Die Casting (Example)-
The inner surface of the die-casting sleeve preliminary body A1 was machined to have an inner diameter of 105 mm from the end where the plunger insertion port 8 is provided to 200 mm in the longitudinal direction. The entire die-casting sleeve preliminary body A1 after machining was subjected to quenching and tempering to adjust the hardness to about 45 HRC.

On the other hand, a ring-shaped article having an outer diameter of 105 mm, an inner diameter of 85 mm, and a length of 200 mm was prepared as the member 5 provided on the inner surface of the die casting sleeve preliminary body A1 (ring wall thickness 10 mm). This ring-shaped article had the composition of components shown in Table 1, and the hardness was adjusted to about 53 HRC by quenching and tempering.

This ring-shaped article was shrink-fitted onto the machined inner surface of the die casting sleeve preliminary body A1. After the shrink fitting, the clamp ring was fixed to the end of the die casting sleeve preliminary body A1 so that the ring-shaped article would not come off from the die casting sleeve preliminary body A1.

After the ring-shaped article was shrink-fitted, the side surface of the die casting sleeve preliminary body A1 was machined to provide the molten metal supply port 2. The molten metal supply port 2 was provided at a position of 60 to 160 mm in the longitudinal direction from the end where the plunger insertion port 8 was provided. Further, the inner surface of the ring-shaped article after the shrink fitting was subjected to finishing machining. A flow path is formed by the inner surface of the die casting sleeve preliminary body A1 and the inner surface of the ring-shaped article. The appearance of the die-casting sleeve A (or die-casting sleeves B to D described later) is shown in FIG.

"All inner surfaces" of the die casting sleeve preparatory body A1 after the ring-shaped article was provided were subjected to a surface treatment to obtain the die casting sleeve A of the example. On the inner surface of the die casting sleeve, first, a nitride layer having a thickness of about 0.3 mm is formed by gas soft nitriding treatment, and then a magnetite layer having a thickness of about 0.01 mm is formed on the nitride layer by steam treatment. It formed and it was set as the surface treatment layer 5b.

-Preparation of sleeve B for die casting (comparative example)-
The entire die-casting sleeve preliminary body B1 was quenched and tempered to adjust the hardness to about 45 HRC. A molten metal supply port 2 is provided on the side surface of the die casting sleeve preliminary body B. The molten metal supply port 2 is provided at a position of 60 to 160 mm in the length direction from the end where the plunger insertion port 8 is provided. Then, "all inner surfaces" of the die casting sleeve preliminary body B1 after the quenching and tempering were subjected to a surface treatment to obtain a die casting sleeve B of a comparative example. A nitride layer having a thickness of about 0.3 mm was formed on the inner surface of the die-casting sleeve by gas soft nitriding treatment to form a surface treatment layer 5b.

<Evaluation of melting resistance of sleeves A and B for die casting>
The die-casting sleeves A (Example) and B (Comparative Example) were mounted on an 800-t cold chamber type die-casting apparatus, and die-casting of an aluminum alloy ADC12 (Fe: 1.3 mass% or less) for die-casting was performed. The temperature of the metal melt of ADC 12 during die casting was 680°C. Then, when the number of shots (the number of times die casting was performed) reached 40,000, the inner surfaces of the positions where the melt supply ports 2 of both sleeves were provided were observed.

The observation result of the die casting sleeve A is shown in FIG. 4, and the observation result of the die casting sleeve B is shown in FIG. 5, respectively. As shown in FIG. 4, a sound surface treatment layer 5b remained on the inner surface of the die casting sleeve A, and neither chemical nor physical erosion was observed. On the other hand, as shown in FIG. 5, on the inner surface of the die casting sleeve B, the surface treatment layer 5b is destroyed just below the molten metal supply port 2, and the material (that is, SKD61) is also depleted. , Significant melting loss was observed.

<Production of sleeve for die casting>
Cylindrical die casting sleeve preforms C1 and D1 having an outer diameter of 200 mm, an inner diameter of 85 mm and a length of 550 mm were prepared. The material of the die-casting sleeve preliminary bodies C1 and D1 is SKD61.

-Preparation of sleeve C for die casting (example of the present invention)-
The inner surface of the die-casting sleeve preliminary body C1 was machined so that the inner diameter of the portion from the end where the plunger insertion port 8 was provided to 200 mm in the longitudinal direction was 95 mm.
On the other hand, as the member 5 provided on the inner surface of the die-casting sleeve preliminary body C1, a welding rod having the component composition shown in Table 2 was prepared. Then, by the overlay welding using this welding rod, two overlay layers were formed on the machined inner surface of the die casting sleeve preliminary body C.
Then, the entire die-casting sleeve preliminary body C after the overlay welding was subjected to quenching and tempering so that the hardness of the SKD61 portion was about 45 HRC. As a result, the hardness of the buildup layer was also about 45 HRC.
After that, the side surface of the die-casting sleeve preliminary body C after forming the build-up layer was machined to provide the molten metal supply port 2. The molten metal supply port 2 was provided at a position of 60 to 160 mm in the length direction from the end where the plunger insertion port was provided.
The finishing buildup was performed on the buildup layer to give a finish thickness of the buildup layer of about 5 mm. As a result, a flow path was formed on the inner surface of the die casting sleeve preliminary body C1.
"All the inner surfaces" of the die casting sleeve preparatory body C1 were subjected to surface treatment to obtain a die casting sleeve C of the example. On the inner surface of the die casting sleeve, first, a nitride layer having a thickness of about 0.3 mm is formed by gas soft nitriding treatment, and a magnetite layer having a thickness of about 0.01 mm is formed on the nitride layer by steam treatment. , And the surface treatment layer 5b.

-Production of sleeve D for die casting (comparative example)-
The entire die-casting sleeve preliminary body D1 was quenched and tempered to adjust the hardness to about 45 HRC. A molten metal supply port 2 is provided on the side surface of the die casting sleeve preparatory body D1 at a position of 60 to 160 mm in the length direction from the end where the plunger insertion port 8 is provided.
"All inner surfaces" of the die casting sleeve preform D1 after the quenching and tempering were subjected to a surface treatment to obtain a die casting sleeve D of a comparative example. A nitride layer having a thickness of about 0.3 mm was formed on the inner peripheral surface of the die casting sleeve by a gas soft nitriding treatment to form a surface treatment layer 5b.

<Evaluation of melting resistance of sleeves C and D for die casting>
The die-casting sleeves C (Example) and D (Comparative example) were mounted on an 800-t cold chamber type die-casting apparatus to perform die-casting of an aluminum alloy for die-casting (Fe: less than 0.6%). The temperature of the molten metal of the aluminum alloy during die casting was 720°C.

In this die casting apparatus, the molten metal supplied from the molten metal supply port 2 was poured with a force so as to drop to a position obliquely below the molten metal supply port 2 by 45°. After die casting, the inner surfaces of the sleeves at the positions where the molten metal supply ports 2 were provided were observed.

FIG. 6 is a photograph of a portion 4 of the sleeve C for die casting which faces the molten metal supply port 2 after 4,500 times of die casting. In the figure, a circle indicates a position obliquely below the melt supply port 2 by 45°, and a star indicates a position directly below the melt supply port 2. As shown in FIG. 6, in the die-casting sleeve C, physical melting loss was observed at a position 45° obliquely below the molten metal supply port 2 where the impact energy due to the molten metal is considered to be large at 4,500 shots. However, the build-up layer still remained. The sound surface treatment layer 5b remained right below the molten metal supply port 2, and both chemical and physical melting loss was suppressed.

FIG. 7 is a photograph of the portion 4 of the die casting sleeve D facing the molten metal supply port 2 after 500 times of die casting. In the figure, a circle indicates a position obliquely below the melt supply port 2 by 45°, and a star indicates a position directly below the melt supply port 2. As shown in FIG. 7, in the die casting sleeve D, at the time of 500 shots, a remarkable physical melt loss was observed at a position 45° obliquely downward from the molten metal supply port 2 and was found immediately below the molten metal supply port 2. However, significant chemical erosion was observed.

The material forming the inner surface of the sleeve for die casting was assumed, and the melting resistance of this material was evaluated. Table 3 shows the component composition of the evaluated materials.

First, the materials 1 to 4 in Table 3 were processed into the shape of the test piece 16 having the dimensions (unit: mm) shown in FIG. At this time, the raw material 1 is a sintered material obtained by HIP (hot isostatic pressing) a metal powder having the composition shown in Table 3. The hardness of each of the test pieces 16 is material 1:70 HRC, material 2:53 HRC, material 3:45 HRC, and material 4:45 HRC.
Next, as shown in FIG. 9, the test piece 16 was moved up and down at a cycle of 90 rpm and a reciprocating height of 30 mm to carry out a melting damage test in which it was repeatedly immersed in the molten metal 17. The metal melt 17 is an aluminum alloy AC4C (Fe: 0.5 mass% or less) specified in "Aluminum alloy casting" of JIS-H-5202:2010, and its temperature was maintained at 700°C by a heater 18. .. The test time was 2 hours.
Then, before and after the melting loss test, the melting loss rate (%) was calculated according to the following formula based on the difference in weight of the test pieces (that is, the weight reduction). The smaller the value of this melting loss rate, the better the chemical melting resistance. The results are shown in Table 4.
Melt loss rate (%)={(weight before test−weight after test)/weight before test}×100

From the results of Table 4, the test pieces of the raw materials 1 to 3 showed less wear of the test pieces and excellent chemical erosion resistance as compared with the test piece of the raw material 4. Moreover, the form of physical erosion that could be caused by moving the test piece up and down was not confirmed. And, among the test pieces of the raw materials 1 to 3, the test piece of the raw material 1 having a composition with a C content of more than 1.0% and a large content of W, Mo, and V has a high hardness, and particularly It was excellent in melting resistance.

This application is based on the Japanese patent application filed on Aug. 31, 2016 (Japanese Patent Application No. 2016-169254), the contents of which are incorporated herein by reference.

According to the present invention, there is provided a die casting sleeve excellent in melting resistance and a method for manufacturing the same.

1 Die-casting sleeve 2 Molten metal supply port 3 Preliminary body 3a Expanded part 3b First opening 4 Site facing the molten metal supply port 5, 51 Member 5a Second opening 5b Surface treatment layer 6 Molten metal discharge port 7 Flow path 8 Plunger insertion port 16 Test piece 17 Metal melt 18 Heater

Claims (12)

A sleeve for die casting having a flow path inside,
A molten metal supply port for supplying a molten metal to the flow path from the outside penetrates from the outer surface to the inner surface of the sleeve for die casting,
Site facing at least the melt feed port of the inner surface forming the flow path, in mass%, C: 0.4% to 2.5% or less, Si: 1.0% or less, Mn: 1.0% A die-cast member made of a material having a component composition of Cr: 3.0% or more and 12.0% or less, Mo: less than 1.0%, balance Fe and impurities, and having a quenched and tempered structure. Sleeve. A sleeve for die casting having a flow path inside,
A molten metal supply port for supplying a molten metal to the flow path from the outside penetrates from the outer surface to the inner surface of the sleeve for die casting,
Site facing at least the melt feed port of the inner surface forming the flow path, in mass%, C: 0.4% to 2.5% or less, Si: 1.0% or less, Mn: 1.0% Hereinafter, Cr: 3.0% or more and 12.0% or less, one or two of Mo and W according to the relational expression of (Mo+1/2W): 1.6% or more and 15.0% or less, balance Fe and A sleeve for die casting, which is made of a material having a composition of impurities and has a tempered and tempered structure. The die-casting sleeve according to claim 1 or 2, wherein the component composition of the material is C: 0.4% or more and less than 1.0% in mass%. The component composition of the material is% by mass, C: 1.0% or more and 2.5% or less, and
The die casting sleeve according to claim 1, wherein the material is a sintered material. The sleeve for die casting according to any one of claims 1 to 4, wherein the composition of the material further contains V, and in mass%, V: 6.0% or less. 6. The component composition of the material further contains at least one of Co and Nb, and in mass%, Co: 10.0% or less and Nb: 3.0% or less. The die casting sleeve described in. A method of manufacturing a die casting sleeve having a flow path inside, a melt supply port for supplying a metal melt from the outside to the flow path, which penetrates from an outer surface to an inner surface,
Prepare a spare body that will be the sleeve for die casting,
At least one of the inner surface forming the flow path, the portion facing the portion serving as the portion facing the molten metal supply port or the melt feed port, in mass%, C: 0.4% to 2.5% or less, Si: 1.0% or less, Mn: 1.0% or less, Cr: 3.0% or more and 12.0% or less, Mo: less than 1.0%, and a material having a component composition of balance Fe and impurities A method of manufacturing a sleeve for die casting, comprising providing a member which is returned. A method of manufacturing a die casting sleeve having a flow path inside, a melt supply port for supplying a metal melt from the outside to the flow path, which penetrates from an outer surface to an inner surface,
Prepare a spare body that will be the sleeve for die casting,
At least one of the inner surface forming the flow path, the portion facing the portion serving as the portion facing the molten metal supply port or the melt feed port, in mass%, C: 0.4% to 2.5% or less, Si: 1.0% or less, Mn: 1.0% or less, Cr: 3.0% or more and 12.0% or less, and one or two of Mo and W according to the relational expression of (Mo+1/2W): 1. A method of manufacturing a sleeve for die casting, which comprises providing a member obtained by quenching and tempering a material having a composition of 6% or more and 15.0% or less and the balance of Fe and impurities. The method for manufacturing a sleeve for die casting according to claim 7 or 8, wherein the component composition of the material is C: 0.4% or more and less than 1.0% by mass%. The method for producing a die casting sleeve according to claim 7 or 8, wherein the material is a sintered material having a composition of mass% and C: 1.0% or more and 2.5% or less. The method for producing a die casting sleeve according to claim 7, wherein the component composition of the material further contains V, and in mass%, V: 6.0% or less. The composition of the material further contains at least one of Co and Nb, and in mass%, Co: 10.0% or less and Nb: 3.0% or less, 12. A method for manufacturing a sleeve for die casting according to.

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