KR20130097681A - Method for surface treating - Google Patents

Abstract

PURPOSE: A shape and structure of a short runner with improved wear resistance, and a surface processing method thereof are provided to implement not only effective and continuous wear resistance but also excellent suitability especially for a tool with a thin wall. CONSTITUTION: A surface processing method of a shape and structure of a short runner with improved wear resistance comprises the following steps. A metal object to be processed is provided. The metal object is coated through a vapor deposition process on a predetermined position. The coating is implemented by a coating substance which is selected from a group composed of a carbide, a nitride, an oxide, and a mixture of the carbide, the nitride, and the oxide. The coating substance is a substance which is selected from a group which is composed of a titanium carbide, a titanium nitride, a titanium bromide, a vanadium carbide, a chromium carbide, an aluminum oxide, a silicon nitride, titanium, a titanium-aluminum nitride, and an aluminum-chrome nitride; and any one between the nitride and the carbide from the same substances of the group.

Description

 Shape and structure of short runner with improved wear resistance and surface treatment method {METHOD FOR SURFACE TREATING}

The present invention relates to a shape and structure of the short runner with improved wear resistance and a surface treatment method.

FIELD OF THE INVENTION The present invention relates to a method for surface treatment of metals for improved wear resistance, and more particularly to extrusion tools-in particular disk-type pressings having at least one shaping opening for the extrusion of metals such as aluminum or aluminum alloys or Extrusion die-relates to a surface treatment method, the extrusion tool may comprise steel, cemented carbide having a surface coating.

The hardness of conventional pressing tools currently used for the production of molded aluminum parts does not provide satisfactory wear resistance. For this reason, such extrusion tools are cured using a variety of known processes.

Extrusion tools made of hot-working steel are more commonly cured after fabrication fabrication to about 46-50 HRC, and then by cavity sinking by grinding, high speed machining, machining centers, EDM and wire-EDM. It is finished. Extrusion tools are generally tested on aluminum pressing machines and, if necessary, modifications are made. If the extrusion tool is then ready for extrusion operation, it is set by nitriding to a surface hardness of about 1000 Hv in a pre-defined manner and that these hardness values provide adequate wear resistance when in practical use. Shows.

Known nitriding processes include salt bath nitriding with cyanate. However, this process brings serious environmental problems. Nitriding with gas has the disadvantage that the resulting cured layer is relatively thick and as a result has a very limited level of toughness. In addition, although there is a plasma nitridation treatment method, this process is not suitable for a tool having a thin slot in the opening.

Known curing processes involving nitriding also have a common drawback that the hardening layer diffuses at increasing temperatures, ie, temperatures of about 500 degrees, for example, layers produced by salt bath nitriding treatments after about 15 hours No longer exists.

In the pressing operation, if the nitriding layer has disappeared due to the diffusion effect, the pressing operation must be stopped and the tool is pickled free, cleaned and nitrided again. Through frequent addition-nitriding treatment near the tempering temperature of the steel used, the hardening and base strength are continuously reduced, resulting in early failures. Thus, for example in the case of a thin-walled tool, the service time that can be achieved is between about 30 and 1000 pressing operations before an updated further -nitriding process is required with the disadvantages of incidental cost.

Conventional tool processing process consists of heat treatment-> polishing-> arc processing. In the case of conventional arc processing, the surface property change occurs by R processing at the inlet and outlet of the bearing surface. The change in surface properties can be reduced.

However, even when the high-speed machining, there is a problem that the accumulated tolerance occurs when using aluminum.

In order to overcome the above problems, the present invention provides a metal processing method that achieves high hardness, which not only provides effective continuous protection from abrasion, but also involves an excellent suitability for tools with particularly thin walls. It aims to provide a solution and to be implemented in a simple manner without environmental pollution.

More specifically, the object of the present invention is to provide a method of reducing accumulated tolerances when machining using a high speed machine.

In order to achieve the object as described above to provide a surface treatment method of a metal for improving the wear resistance,

Providing a metal to be treated;

The method may include coating the metal at a predetermined position by vapor deposition.

The coating may be a material selected from the group consisting of carbides, nitrides, oxides and mixtures thereof.

The coating material is titanium carbide, titanium nitride, titanium boride

It may be one selected from the group consisting of vanadium carbide, chromium carbide, aluminum oxide, silicon nitride, titanium, aluminum oxide, titanium aluminum nitride, and aluminum chromium nitride, and nitrides and carbides of these materials.

Before and after coating the metal may further include a treatment step for increasing the hardness of the metal.

According to the present invention as described above it is possible to treat the metal to have a high wear resistance.

1 and 2 show an embodiment according to the present invention.

Hereinafter, the present invention will be described in detail. In the present invention, in the processing of the tool, the heat treatment-> polishing-> arc processing is replaced with the arc processing by the high speed processing machine to reduce the surface property change caused by the arc processing.

However, due to the simultaneous processing using a high speed processing machine, it is possible to process with a small change in the surface properties, but in the case of using aluminum (particularly at the 450 ° C extrusion temperature of aluminum), the cumulative tolerance Has occurred.

In order to reduce the cumulative tolerance, this problem can be solved by adding a deposition process using a deposition method. Deposition plants can be accomplished using two methods, PVD and CVD, which are described in more detail below.

The coatings completed using the vapor deposition method are selected from the group consisting of titanium carbide, titanium nitride, boron titanium, vanadium carbide, chromium carbide, aluminum oxide, silicon nitride, titanium aluminum nitride, aluminum chromium nitride, and combinations thereof. The coating material is made of the selected coating material. In the physical vapor deposition process (PVD), the target metal and the reactant gas are deposited on the surface of the metal in a plasma state in a vacuum chamber below 500 ° C. It is apply | coated to the surface of a metal by the gas deposition process at the temperature of 1000 degreeC or more.

In the chemical vapor deposition (CVD) process, a solid or liquid raw material must be injected into the reaction chamber in a gaseous state, and thus an additional device for gasifying the raw material is needed. An additional device is also needed to prevent condensation again.

In the case of PVD coating according to the present invention, after processing the metal to be treated primarily, the washing process is performed on the finished extrusion tool and the setting is performed to apply the coating to the PVD vacuum chamber. The extrusion tool is loaded into a PVD vacuum chamber and a vacuum pump is used to deposit the coating material.

Creates a high vacuum below 5X10 ^-5 mbar. After the high vacuum is formed inside the vacuum chamber and the chamber is heated, a thin oxide film on the surface of the extrusion tool is removed through an etching process using an inert gas such as argon gas. After the etching process, the target metal is evaporated at about 450 ℃ and the reactive gas is injected to form a plasma state. Then, a negative voltage is applied to the extrusion tool. Ionized (+) ions are deposited on the surface of the extrusion tool. When the deposition is complete, cooling is accomplished by cooling gas.

This is done by the following process.

1) providing a metal to be treated;

2) primarily processing the metal, including hardening;

3) coating the metal by the PVD process with the coating material described above.

When the PVD treatment is carried out according to the present invention, the high hardness thin film obtained by the PVD process evaporates the alloy and the metal material to be deposited under high vacuum conditions in an ionized state using ARC (arc) and reacts the reactive gas. After injection, the target metal vapor and the reactive gas are converted into a plasma state, and a high hardness ceramic thin film is formed on the surface of the extrusion tool by applying a negative voltage. This ceramic thin film has a high hardness of Hv 3,000 or more, which improves the wear resistance of the extrusion tool.

Since the process temperature of PVD treatment is about 450 ℃, in the case of cemented carbide or hot-drilled steel such as STD61 grade, the initial hardness is maintained without additional post-heat treatment, and there is no deformation of the extrusion tool size by the process temperature. In order to maximize the effect of improving the wear resistance of the coating, the molded part of the extrusion tool must make the optimum surface roughness before the PVD treatment and maintain the initial surface roughness after coating.

In particular, aluminum chromium nitride is chemically stable, has excellent abrasion resistance, and maintains oxidation resistance even at a high temperature of 1,100 ° C., thereby showing excellent abrasion resistance.

In addition, the PVD coating can be applied to the surface of the nitrided hot-hole oral cavity, and the surface of the extruded tool first hardened by the nitriding treatment provides the support base of the more robust PVD coating layer to provide excellent wear resistance.

In the CVD process according to the present invention, after processing the metal to be treated first, the gas-like injection gas (TiCl _4, etc.) is transferred to the surface of the metal, where nitrogen and hydrogen gas are injected together and processed. Heat the metal to be 850 to 1000 degrees Celsius, or even more than 1000 degrees Celsius. In this process, TiN (s) is formed on the surface of the metal and is grown. Quenching and tempering can then be done to achieve high hardness.

This is summarized by the following process.

1) providing a metal to be treated;

2) primarily processing the metal, including hardening;

3) coating the metal at a predetermined position by a CVD process with the above-described coating material.

4) additional hardness step

After the first machining step in 2), a high-speed machining process may be added.

An important chemical reaction can be represented by the formula: This chemical reaction is a CVD reaction, where the starting product is in the form of a vapor, the main product is separated in the form of a solid body, and the by-product is in gaseous form. The overall reaction equation for titanium nitride according to the high temperature CVD-process is described herein as an example, where

(g) = gas and (s) = solid:

H ₂

TiCl ₄ (g) + 1/2 N ₂ (g) + 2 H ₂ (g)-> TiN (s) + 4HCl (g)

850-1000 ℃

In this case, the reducing carrier gas H ₂ is excessively added. In the reaction the metal is heated to at least 850 degrees Celsius and preferably to at least 1000 degrees Celsius and the reaction also takes place under these conditions, after which the quenching and Tempering takes place.

Thermally activated CVD-processes-chemical vapor deposition-are produced by growth on surfaces or by diffusion of borides, carbides, nitrides, oxides, for the production of single crystals, for the injection of fiber structures into carbon or ceramics, and in general The procedure according to the invention forms an abrasion resistant layer for increasing the durability of the tool itself without further post-treatment, which is applied by a CVD process and is preferably at least 1000 ° C. It is provided because of the coating applied at a temperature, which is basically superior to conventional curing processes that maintain below a temperature of about 500 to 600 ° C.—the tempering limit of the steel material used.

Certainly, CVD-coating requires hardening of the finished tool after the coating operation but by the proper control of flow phenomena in the tool and in particular to the invention the invention of low-torsion hot-acting steel By choice according to such a technique, such a technique can be managed in a surprising and unpredictable manner, providing excellent properties with regard to curing and wear resistance.

In the process according to the invention, in addition to TiCl ₄ described above, titanium carbide, titanium nitride, titanium boride, vanadium carbide, chromium carbide, aluminum oxide and silicon nitride may be used. Depending on which material is used, it is possible to achieve microhardness levels between Hv 2000 and Hv = about 4000. Titanium carbide or aluminum oxide, in particular applied by a CVD-process, has excellent toughness, while chromium carbide, for example, is particularly good in wear resistance and less affected by cracks or pores. In particular also titanium carbide is further distinguished by its advantageous frictional properties.

Thanks to the scattering performance inherent in precise, uniform and uniform coating CVD procedures even with complex metals, it is possible to apply uniform, uniform coatings with particularly high precision.

Advantageous Ratios of Defect Ratio and Tool Quality In the fabrication and coating of extrusion dies according to the present invention, well-managed CVD-processes provide significant procedural reliability and good reproducibility, with very low rejection levels, It is possible to produce very high quality tools

Preferably, the starting materials used in the manufacture of the extrusion dies according to the invention are solid steels with good high temperature properties, for example alloyed with Cr, Mo or tungsten, for example ESR (Electro-) for high rigidity levels. It can be melted by slag remelting) and cemented carbide can be used.

Even in the multilayer structure the coating materials described above, any combination of these coating materials, or alternative suitable materials are deposited by CVD-process at a temperature of about 700 to about 1050 ° C. for 5-6 hours.

Tools made in this way are cured again after such coating procedures.

The metal used is chosen such that no significant twist or deformation occurs due to the rise in temperature that is connected to the CVD-coating process.

The coating formed by the vapor deposition method used in accordance with the invention additionally provides excellent wear resistance.

Good adhesion; Very good adhesion is achieved between the base material and the coating by means of vapor deposition due to the metallurgical characteristics.

It can be applied with respect to the actual extrusion operation-for example with respect to the molded aluminum part-using a tool of that kind made in accordance with the invention, in which the present invention also takes into account the flow properties of the aluminum and thus Considerations involved in design construction and hardening, in this regard it is particularly desirable to consider such flow characteristics by previous simulation calculations.

As a result, this provides for a greatly increased service time and maintenance of the tool is also no longer particularly needed as described at the beginning of this specification. Moreover, a low level of friction is advantageously achieved due to the coating material applied by the vapor deposition process according to the invention, the treatment or pressing speed of the extrusion die is improved, and better surface quality of the molded article is possible.

The deposition method according to the present invention can be used even after high-speed processing and can be used for the purpose of extending the life of a tool by using a general mold.

Claims (4)

As the shape, structure and surface treatment method of short runner with improved wear resistance
Providing a metal to be treated;
Coating the metal at a predetermined location by vapor deposition;
Shape and structure of short runner with improved wear resistance and surface treatment method
The method of claim 1, wherein the coating is a material selected from the group consisting of carbides, nitrides, oxides, and mixtures thereof.
The method of claim 1, wherein the coating material is selected from the group consisting of titanium carbide, titanium nitride, titanium boride, vanadium carbide, chromium carbide, aluminum oxide, silicon nitride, titanium, aluminum oxide, titanium aluminum nitride, and aluminum chromium nitride. Wear resistance improved short runner, characterized in that any one of the nitride, carbide of these materials and surface treatment method
The method of claim 1, further comprising a treatment step for increasing the hardness of the metal before and after coating the metal.

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