KR20210084854A - Manufacturing Al Extrusion Mold with Cemented Carbide Coating from CVD Technology - Google Patents

Abstract

Disclosed is a method of manufacturing an aluminum extrusion mold processing a carbide material through chemical vapor deposition. The method of manufacturing an aluminum extrusion mold processing a carbide material through chemical vapor deposition includes the following steps of: arranging a base material including at least one of metal selected from a group composed of cobalt, chromium, manganese, molybdenum and copernicium and nonmetal selected from a group composed of silicon, phosphorus, carbon, oxygen and sulfur; including a first coating layer forming a coating with metal selected from a group composed of titanium, on the base material; and including a second coating layer forming a coating with nonmetal selected from a group composed of aluminum, silicon, phosphorus, carbon, oxygen and sulfur, which are made to improve hardness, on the first coating layer. The first and second coating layers have ratios of 3-3.5:2-2.5 in thickness, respectively. Therefore, the present invention is capable of improving the quality of an extruded product.

Description

Manufacturing Al Extrusion Mold with Cemented Carbide Coating from CVD Technology

The present invention relates to a method for manufacturing an aluminum extrusion mold coated with cemented carbide by applying CVD coating technology to the surface of a high-temperature tool steel material. Specifically, for metal extrusion in which a high-viscosity aluminum alloy is pressed at high pressure through a limited opening of an extrusion mold. It is about mold making.

Extrusion is a kind of metal plastic processing method. When a metal mass is put into a container and pressure is applied, the metal is discharged and molded according to the shape of the groove of the mold. Currently, many products are manufactured by extrusion molding.

A general extrusion mold may have a structure in which the upper and lower parts are divided into two parts based on the center and then assembled by fastening the upper and lower parts with bolts. In this case, if a part of the grooved forming hole is formed according to the product shape of the product to be extruded, only the damaged part can be replaced or repaired without the need to replace the entire core mold.

However, when the upper and lower molds are forcibly fitted and extruded, the mandrel and the die expand due to pressure and thermal expansion, which may cause eccentricity little by little, and this eccentricity is a mold product that must maintain fine precision. can lead to fatal errors.

In addition, the core core of the conventional mold core consists only of a combination of a simple straight line with an outline and an inner line. Since the flow rate of the extruded material in a semi-molten state is not constant in this core core, a load can be applied to the core core or the outer wall of the mold. have. In addition, a dead zone is formed in an angled place, and foreign substances may be deposited. In the end, there is a problem that may result in deterioration of the quality of the final product and the occurrence of defects.

On the other hand, CVD is a method called solid material precipitation from chemical vapor. It sends vapor of a compound (mainly a metal halide) of a substance to be coated on the surface of a structure maintaining high temperature with a transport gas and thermally decomposes it on the surface It refers to a method of coating or depositing a metal by hydrogen reduction, which is used for surface treatment of metal or used in semiconductor processing.

Therefore, a lot of research has been done on methods of increasing wear resistance and making an optimized extrusion mold by forming a hardened carbide on the surface of a high temperature tool steel base material by using a high temperature (HT)-CVD coating method. However, despite many studies, the coating layer on the base material of the extrusion mold has low durability and abrasion resistance.

Republic of Korea Patent Publication No. 10-2015-0093923 (2015.08.19.) Republic of Korea Patent Publication No. 10-2015-0069470 (2015.06.23.)

The present invention was devised in view of the above points, and by applying CVD coating technology to an extrusion mold base material made of a high-temperature tool steel material to form a single-layer or multi-layer coating, a manufacturing method of extruding aluminum having high viscosity and high density properties. Its purpose is to provide

In order to achieve the above object, the present invention provides a method for manufacturing an aluminum extrusion mold in which a hard material is coated on a surface of a high-temperature tool steel by a chemical vapor deposition method, comprising the steps of: preparing a base material including a metal made of hot tool steel; including a first coating layer for forming a coating on the base material with a metal selected from the group consisting of titanium, cobalt, chromium, manganese, molybdenum and copernicium; and a second coating layer coated with a metalloid or a non-metal selected from the group consisting of aluminum, silicon, phosphorus, carbon, oxygen and sulfur, which are metals for improving hardness, on the first coating layer.

The Al extrusion mold manufacturing method in which a hard material is coated on the surface of a high-temperature tool steel material by applying the CVD coating technology according to the present invention improves wear resistance, lowers the surface roughness, and reduces the surface roughness of the coating elements by forming at least two coating layers on the base material of the extrusion die. The diffusion ability and thermal conductivity can be improved. These properties work favorably for extrusion applications.

In addition, the Al extrusion mold, in which the hard material is coated on the surface of the high temperature tool steel material by applying the CVD coating technology according to the present invention, reduces friction with Al by the coating layer during pressing, that is, while passing through the extrusion die, and also reduces the thermoelectricity of the coating layer. It has excellent conductivity and can lower the processing temperature of extruded metal. The reduced processing temperature can again suppress the unwanted oxidizing effect of the extruded metal and improve the quality of the extruded product.

1 is a longitudinal cross-sectional view and a partially enlarged view of a mandrel and an extrusion die according to the present invention.
Figure 2 is a schematic photograph in which a multi-layer coating layer is formed on the base material of the extrusion die according to the first embodiment of the present invention.
Figure 3 is a photograph and component content graph schematically showing the surface of the extrusion die including the coating layer according to the present invention.

Hereinafter, a method of manufacturing an Al extrusion mold in which a hard carbide material is coated on a high temperature tool steel surface by applying a CVD coating technology according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a longitudinal cross-sectional view and a partially enlarged view of a mandrel and an extrusion die according to the present invention.

Referring to FIG. 1 , the extrusion mold 10 may include a mandrel 11 and a die 20 acting therewith. The extrusion mold 10 has at least two fixing parts 13 formed by projections of a mandrel 11 composed of an upper mold and a lower mold, and faces the die 20 and can be installed to face each other. . The mandrel 11 can extrude metal. The mandrel 11 may include a mandrel carbide 15 that is the hardness when the depth of the '凹' shape with respect to the center is 0, that is, the hardness when not work hardening. Further, the mandrel 11 is connected with a plurality of connecting tubes 30 provided around it, and the plurality of connecting tubes 30 are formed between the mandrel 11 and the annular surface of the die 20 . It can be used to guide the ductile metal during press operation through the extrusion direction 'P' in (11).

The die 20 may include a die carbide 25, which is the hardness when the depth of the '凹' shape with respect to the center is 0, that is, the hardness when work hardening is not performed. The conventional mandrel 11 and the die carbide 25 consisted of only a combination of a simple straight line with an outline and an inner line thereof, and the flow rate of the extruded material in a semi-molten state may not be constant. This problem occurs when a load is applied to the outer wall of the die carbide (25) mold and a dead zone is formed in an angled place, resulting in the deposition of foreign substances. There are problems that can lead to results. Therefore, the present invention may have a constant 'A' on the central axis with respect to the surface of the die carbide 25 facing the mandrel 11 in order to solve this problem. This 'A' means an inclined angle, and it can be inclined at about 5 to 10˚, and can reduce the dead zone and prevent foreign substances from being deposited.

Figure 2 is a schematic photograph of a multi-layer coating layer formed on the extrusion die base material according to the first embodiment of the present invention.

Referring to FIG. 2 , the method for manufacturing an aluminum extrusion mold 10 by processing a cemented carbide material by chemical vapor deposition (CVD) according to the present invention includes preparing a base material 100, forming a first coating layer 110 and forming the second coating layer 120 .

First, the step of preparing the base material 100 is made of a general hot tool steel, specifically cobalt (Co), chromium (Cr), manganese (Mn), molybdenum (Mo) and a group consisting of copernicium (Cn) may include at least one of a metal selected from and a non-metal selected from the group consisting of silicon (Si), phosphorus (P), carbon (C), oxygen (O), and sulfur (S). In detail, the base material 100 contains 0.17 to 0.23 wt% of carbon (C), 0.15 to 0.35 wt% of silicon (Si), 0.40 to 0.60 wt% of manganese (Mn), and 0.035 wt% of phosphorus (P) up to 0.035 wt% , sulfur (S) at a maximum of 0.035 wt%, chromium (Cr) in an amount of 9.00 to 10.00 wt%, molybdenum (Mo) in an amount of 1.80 to 2.20 wt%, and cobalt (Co) in an amount of 9.50 to 10.50 wt%.

[Table 1] shows various examples of the chemical composition constituting the base material 100 as follows.

On the other hand, the base material 100 of the extrusion die 20 may have a region that is easy to be exposed and is susceptible to wear, that is, a round region, a sliding region, a brace region, or a conical region. Therefore, if the weak properties of the base material 100 are supplemented, it is possible to reduce wear due to friction. Referring to FIG. 2 , in the step of forming the first coating layer 110 , a coating may be formed on the base material 100 with a metal selected from the group consisting of titanium (Ti). Existing coatings commonly used may include TiCN, TiC, TiN, TiBN, and the like. TiCN indicates the presence of each element and may include providing alternative metals to Ti or additionally adding other metals. Ti groups may be mainly used as the first coating layer 110 which is a base layer. In order to improve the first coating layer 110 , it may further include one or a plurality of additional coating layers having specific properties. TiBN provides high hardness to the base material 100 compared to other coating materials and provides strong corrosion resistance, thereby extending the life of the tool compared to a general tool. In addition, if another thin film material is formed after the TiBN layer is formed, the base material of the tool is strengthened to reduce the working deviation of the tool. In the case of multi-layer coating, it is combined with the excellent mechanical properties of other layers to extend the life of the tool and reduce the deviation. and make the work easier. That is, when the TiBN layer is formed than when the TiCN, TiC, or TiN layers are formed, the degree of diffusion of TiBN into the base material is higher than that of C and N. _{In order to form the TiBN coating layer, nitrogen, hydrogen, etc. are reacted with a compound such as TiCl 4} and BCl ₃ in gaseous form at about 700 degrees Celsius to 1000 degrees Celsius to form a first coating layer 110 such as TiBN on the surface of the metal. In the step of forming the second coating layer 120 , aluminum (Al), silicon (Si), phosphorus (P), carbon (C), which are metals that improve hardness on the first coating layer 110 , The coating may be formed of a non-metal selected from the group consisting of oxygen (O) and sulfur (S).

After the average temperature process, the second coating layer 120 may be formed through the following reaction using _{Al 2} O _{3 .}

The second coating layer 120 is also referred to as a functional layer, and as opposed to the first coating layer 110 , it is deposited at 1000 degrees at a so-called high temperature, and after the process is finished, it may have a layer thickness of 2 μm to 5 μm. In addition, the second coating layer 120 is hard and acts synergistically with the first coating layer 110 to reduce wear due to the extrusion process. On the other hand, since the C/N ratio of the second coating layer 120 having an average temperature does not change through the subsequent application of the second coating layer 120 , it maintains the intrinsic properties of the first coating layer 110 and at the same time has a columnar or stem shape. Since it has a structure, good adhesion with the first coating layer 110 can be achieved.

As shown in FIG. 2 , the thickness of the first coating layer 110 and the second coating layer 120 may have a ratio of 3 to 3.5: 2 to 2.5, respectively. That is, the first coating layer 110 may have a thickness of about 6-7 μm, and the second coating layer 120 may have a thickness of about 4-5 μm. At this time, since the extrusion mold 10 having the first and second coating layers 110 and 120 has such a thickness ratio, the wear resistance is improved, the surface roughness is lowered, and the diffusion ability and thermal conductivity of the coating elements can be improved. .

3 is a photograph and a component content graph schematically showing the surface of the extrusion die on which the coating layer according to the present invention is formed.

Referring to FIG. 3 , as a photograph schematically showing the surface of the extrusion die 20 on which the coating layer according to the present invention is formed, it can be seen that the first and second coating layers 110 and 120 are formed on the base material 100 . . At this time, the component content of the coating layer shown in the graph is iron (Fe) 2.88 wt%, titanium (Ti) 2.10 wt%, silicon (Si) 1.82 wt%, aluminum (Al) 60.38 wt%, oxygen (O) 22.87 wt%, and carbon (C) 9.95 wt% was included.

The second coating layer 120 may include carbon element, and the optimal ratio at the average temperature may be greater than 1 or greater than 1.5 C/N. For example, a C:N ratio of eg 60:440 may be possible in a typical implementation when measuring using secondary ion mass spectrometry (SIMS).

The second coating layer 120 to which the CVD coating technology is applied may be formed of at least one layer and may have improved texture, roughness and thermal conductivity. For example, the second coating layer 120 may have Al ₂ O ₃ , TiBN and TiO, and the average temperature may be coated at a CVD process temperature of 950° C. or higher. However, the present invention is not limited thereto, and the second coating layer 120 may be formed of ZrN, CrN, or CrC.

The present invention is not limited to the above-described extrusion die base material, extrusion material and coating material (enclosed and used gas). Rather, a material suitable for average temperature CVD to implement the present invention is suitable for the layer, and Ti is preferred as the metallic element, but need not be provided. In the context of the present invention, it is possible to dope the layer thus formed, and from the elements already mentioned B, in particular Zr, Cr, etc. may be included. _{In addition, it is not limited to Al 2} O ₃ , which was the main component of the second coating layer 120 that served as a cover or function, and can be variously applied as other TiO layers, MT layers, etc. that can be coated at high temperatures. .

In addition, as a component of the second coating layer 120, other light metals, for example, magnesium alloys or zinc alloys, copper and/or brass-based heavy metal alloys may be considered in addition to aluminum-based alloys. Furthermore, irrespective of the metal extrusion method mentioned above, the present invention is suitable for advantageously treating plastics such as CFK plastics and the like in terms of wear. As a further foreseeable point, in particular hard or abrasive extruded materials (powder metallurgical aluminum with a conceivable high Sl component of up to 14%) are processed and material property values (such as nanoparticles, SiC, etc.) Aluminum with additives to change material characteristic values can also be treated.

The above-described embodiments are merely exemplary, and various modifications and equivalent other embodiments are possible from those of ordinary skill in the art to which the present invention pertains. Therefore, the true technical protection scope of the present invention will have to be determined by the technical idea of the invention described in the claims.

10: Extrusion mold 11: Mandrel
13: fixed part 15: mendrel carbide
20: Die 25: Die carbide
30: connection tube 100: base material
110: first coating layer 120: second coating layer
P: Extrusion direction A: Inclined angle

Claims (1)

In the method for manufacturing an aluminum extrusion mold processing a cemented carbide material by chemical vapor deposition,
Preparing a base material comprising at least one of a metal selected from the group consisting of cobalt, chromium, manganese, molybdenum and copernicium and a non-metal selected from the group consisting of silicon, phosphorus, carbon, oxygen and sulfur;
including a first coating layer for forming a coating on the base material with a metal selected from the group consisting of titanium; and
a second coating layer having a coating formed on the first coating layer with a non-metal selected from the group consisting of aluminum, silicon, phosphorus, carbon, oxygen and sulfur, which are metals for improving hardness,
The thickness of the first coating layer and the second coating layer is 3 to 3.5: a method of manufacturing an aluminum extrusion mold processing a cemented carbide material by chemical vapor deposition, characterized in that having a ratio of 2 to 2.5, respectively.

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