KR20150117725A - Its controlling device and surface heat treatment method - Google Patents

Abstract

The present invention relates to a surface heat treatment method and a control device thereof which allow a compound layer and a diffusion layer of a single material to be simultaneously heat-treated with their surfaces to satisfy their target thicknesses. To achieve this, the surface heat treatment method to laminate the compound layer and the diffusion layer on the single material, comprises: a setting step of setting the target thicknesses of the compound layer and the diffusion layer; a deduction step of deducing target thermal energy levels of the compound layer and the diffusion layer for reaching the target thicknesses of the compound layer and the diffusion layer in a heat treatment condition of applying thermal energy to the single material; a heat treatment step of proceeding with heat treatment by comparing the target thermal energy levels with real-time thermal energy levels measured by applying the thermal energy to the compound layer and the diffusion layer during the heat treatment by applying the thermal energy to the single material. Therefore, the surface heat treatment method and the control device thereof satisfy the target thicknesses of each layer at the same time and allow the easy and convenient heat treatment of products as the rate of relative thermal energy levels for reactions of each layer are set and a thermal cycle model satisfying the rate is set to proceed with the heat treatment to simultaneously apply the thermal energy to each layer to be heat-treated during the surface heat treatment of the single material on which the compound layer and the diffusion layer are formed.

Description

TECHNICAL FIELD [0001] The present invention relates to a surface heat treatment method,

The present invention relates to a surface heat treatment technique in a single material, and more particularly, to a method of setting a thermal cycle model and a ratio of a relative thermal energy value to a reaction of each material, To a surface heat treatment method and a control apparatus therefor, wherein heat treatment is performed while simultaneously satisfying the thickness of the layer formed by each reaction by monitoring the heat energy value.

The sintering process for the heat treatment of different materials simultaneously consists of a diamond tool sintered of two powder materials consisting of a blade part and a body part, an LC filter obtained by sintering a dielectric material and a magnetic material simultaneously, a lightweight automobile part sintered with a steel alloy and an aluminum alloy powder And the like can be used as a technique for simultaneously sintering various kinds of heterogeneous material powders.

The conventional co-sintering method of the different materials first divides the main material and the sub material, secures the sintering quality of the main material first, and sintering the sub material is performed under various heating conditions while varying the type and composition ratio of the powder The sintering heat treatment is aberrantly performed.

Therefore, the existing heterogeneous material heat treatment method has a problem that the intuition and experience of the developer are desperately required, and the possibility of simultaneous sintering and the possibility of sintering are inferior rather than selection of different materials and product development considering superior performance.

In the "heat treatment control method using energy value", which was previously filed by the present applicant and registered with Korean Patent Registration No. 10-0612446, the heating temperature in the furnace is set to a cumulative energy value for sintering And controlling the sintering density in real time during the sintering process.

That is, the above-described technique can monitor the increasing sintering density depending on the energy applied to one kind of material and control the heat treatment because the sintering is terminated when the material reaches the target sintering density.

However, when two kinds of materials are simultaneously injected into a furnace and sintered at the same time, there is a problem that a sintering heat treatment schedule capable of simultaneously satisfying a target sintering density of the two materials can not be presented.

That is, even if one of the two materials reaches a target sintered density, there is a problem that the sintered density of the second material, which is another kind of powder, can not be controlled at all. If three or more kinds of materials are put together and heat-treated, the target sintered density of three or more materials must be achieved at the same time, which is a more difficult problem.

On the other hand, the above-mentioned problems can be exemplified not only in the sintering process but also in the surface modification process.

For example, in the conventional plasma nitriding process, two nitriding layers are formed in a deep nitriding process for abrasion resistance purpose, and the outermost surface is a compound layer (or white layer) in the form of Fe 4 N of about 10 μm, And a nitride layer called a diffusion layer or a practical nitrided layer is formed in which a nitrogen ion is diffused into the inside of the diffusion layer and a surface hardness is increased to a depth of 100 to 600 μm.

The compound layer is a brittle layer itself, and a bonding force is a problem at a thickness of at least a certain level (usually 5 탆). Therefore, a tool which is subjected to an ultimate stress such as a rolling die requires no or minimal compound layer thickness.

The diffusion layer formed by diffusion into the metal of the ions is generally required to be about 300 mu m in the tool, but more than 400 mu m causes the brittleness.

In another case, in the case of plasma oxynitridation for securing corrosion resistance and abrasion resistance, it is required to secure at least 10 탆 thick oxynitride compound layer resistant to corrosion in order to secure corrosion resistance in addition to the conventional abrasion resistance.

Thus, it is necessary to control the thicknesses of the two layers formed on the surface, respectively, even in the case of surface modification such as plasma nitridation or plasma oxynitridation.

Generally, the thickness of the two layers is controlled, and when the total amount of gas to be introduced is determined, the gas ratio of hydrogen and nitrogen is controlled to control the formation of the compound layer. That is, when the formation of the nitride compound layer is to be suppressed as much as possible, the nitrogen ratio is lowered, and in the opposite case, the nitrogen ratio is increased.

However, since the conventional nitriding layer forming method is basically a trial and error method, the temperature and time required for the reaction are changed every time the partial pressure of nitrogen is controlled, so that the test must be restarted at the origin. However, when the nitrogen partial pressure condition without the compound layer is found and the temperature is raised or the time is increased to secure the diffusion layer of the target thickness, the compound layer is regenerated and the test is returned to the origin again.

On the other hand, in the "method for real-time monitoring of nitriding depth in plasma nitriding process ", which was filed and registered as a Korean Registered Patent Publication No. 10-1249539 by the present applicant, a plasma nitriding heat treatment process has been proposed in which a thermocouple The nitriding depth is monitored in real time during the plasma nitriding process by converting the measured product surface temperature into the cumulative energy value for plasma nitriding while measuring the product surface temperature in real time.

However, in the plasma nitridation process described above, only a control method for one layer out of the compound layer and the diffusion layer is presented, and there is a problem that a method of simultaneously satisfying the thicknesses of the two layers can not be proposed. That is, since both reactions are thermal activation reactions, the compound layer and the diffusion layer become thick together during the excessive heat treatment, and when the heat treatment is insufficient, they become thin together, so that it is difficult to simultaneously control the thickness of the two layers.

KR 10-0612446 B KR 10-1249539 B

SUMMARY OF THE INVENTION The present invention has been made in order to solve the conventional problems as described above, and it is an object of the present invention to provide a thermal cycle model and a ratio of a relative thermal energy value to a reaction of each material during a surface heat treatment in which two or more reactions occur simultaneously in a single material , And the thermal energy is applied while actually applying heat energy so as to reach the ratio of the heat energy value, thereby performing heat treatment while simultaneously satisfying the thickness of the layer formed by each reaction, and a control device thereof.

According to an aspect of the present invention, there is provided a method for surface heat treatment to form a compound layer and a diffusion layer on a single material, the method comprising: setting a target thickness of a compound layer and a diffusion layer; A derivation step of deriving a target heat energy value of the compound layer and the diffusion layer to reach a target thickness of the compound layer and the diffusion layer under a heat treatment condition for applying heat energy to the single material; And a heat treatment step of applying heat treatment to the single material by applying heat energy to the compound layer and the diffusion layer during heat treatment, and comparing the measured value of the target heat energy with a real time heat energy value measured by the heat treatment.

The deriving comprises: setting a ratio of a target thermal energy value of the compound layer to reach the target thickness and a target thermal energy value of the diffusion layer; A first securing step of obtaining a target heat energy value of the compound layer through a thermal cycle model forming a relationship between a heating temperature and a heating time; And a second securing step of substituting the thermal cycle model used in the first securing step into the diffusion layer to obtain a target thermal energy value of the diffusion layer.

A third securing step of, when the heat energy value of the diffusion layer obtained in the securing step is not equal to the target heat energy value of the diffusion layer, changing the target heat energy value of the compound layer to another thermal cycle model; And a fourth securing step of substituting the thermal cycle model used in the third securing step S24 into the diffusion layer to obtain a target thermal energy value of the diffusion layer.

The third securing step and the fourth securing step may be repeatedly performed until the thermal energy value of the compound layer and the thermal energy value of the diffusion layer coincide with the target thermal energy value of the compound layer and the target thermal energy value of the diffusion layer.

The surface heat treatment may be a plasma nitridation heat treatment.

In the heat treatment step, when the heat energy value measured in real time is lower than the target heat energy value, the plasma nitridation heat treatment of the material continues, and when the heat energy value measured in real time reaches the target heat energy value, the plasma nitriding heat treatment of the material is terminated The material can be cooled.

The heat energy value can be measured by the following equation (1) using the compound layer formation activation energy and the diffusion layer formation activation energy.

Equation 1

Where T = absolute temperature, Q = activation energy or diffusion layer formation activation energy, R = gas constant, dt = heating hold time.

The compound layer formation activation energy and the diffusion layer formation activation energy can be derived from the relationship between the thermal energy independently applied to the compound layer and the diffusion layer, and the thickness of the compound layer and the diffusion layer.

The constitution of the present invention is an apparatus for controlling surface heat treatment so as to form a compound layer and a diffusion layer on a single material so as to form a laminate therebetween, wherein the target thickness of the compound layer and the diffusion layer is set, and the heat treatment condition for applying heat energy to the single material, A target thermal energy value of the compound layer and the diffusion layer for reaching the target thickness is derived, and when the thermal energy is applied to the single material, the target thermal energy value and the real time thermal energy value measured by applying the thermal energy to the compound layer and the diffusion layer are compared And a control unit controlling the heat treatment to be performed.

The control panel connected to the control unit may be configured to visually confirm the thermal energy values of the compound layer and the diffusion layer measured in real time and the target thermal energy values of the compound layer and the diffusion layer.

According to the present invention, by setting the ratio of the relative thermal energy value to the reaction of each layer during a surface heat treatment in which a compound layer diffusion layer is formed on a single material, and setting a thermal cycle model capable of satisfying this, The heat energy is simultaneously applied to the layer, and the layer is heat-treated to simultaneously and easily heat-treat the product while satisfying the target thickness of each layer.

1 is a view for explaining a heat treatment flow in a surface heat treatment method according to the present invention.
2 is a view for explaining the relationship of the thickness of the compound layer to the thermal energy value of the compound layer in the surface heat treatment method according to the present invention.
3 is a view for explaining the relationship of the thickness of the diffusion layer with respect to the thermal energy value of the diffusion layer in the surface heat treatment method according to the present invention.
4 is a conceptual view for explaining the principle of a surface heat treatment method according to the present invention.
5 is a diagram showing a design example of a thermal cycle model in the surface heat treatment method according to the present invention.
FIG. 6 is a diagram illustrating a control panel monitoring values controlled by a surface heat treatment control apparatus according to the present invention; FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view for explaining a heat treatment flow in the surface heat treatment method according to the present invention, FIG. 2 is a view for explaining the relationship of the thickness of the compound layer to the heat energy value of the compound layer in the surface heat treatment method according to the present invention, FIG. 4 is a conceptual view for explaining the principle of the surface heat treatment method according to the present invention, and FIG. 5 is a view for explaining the principle of the surface heat treatment method according to the present invention FIG. 6 is a diagram illustrating a control panel in which numerical values controlled by the surface heat treatment control apparatus according to the present invention are monitored. FIG. 6 is a diagram illustrating a design example of a thermal cycle model in the surface heat treatment method.

The surface heat treatment method of the present invention comprises a large setting step (S10), a derivation step (S20), and a heat treatment step (S30).

Referring to FIG. 1, a surface heat treatment method in which a compound layer and a diffusion layer are formed on a single material, includes a setting step (S10) of setting a target thickness of a compound layer and a diffusion layer; A derivation step (S20) of deriving a target heat energy value of the compound layer and the diffusion layer to reach a target thickness of the compound layer and the diffusion layer under a heat treatment condition for applying heat energy to the single material; And a heat treatment step (S30) in which heat treatment is performed while comparing the target thermal energy value with a real time heat energy value measured by applying thermal energy to the compound layer and the diffusion layer when heat treatment is performed by applying heat energy to the single material.

That is, when a single material is subjected to a surface heat treatment, a ratio of a relative thermal energy value to a reaction between the compound layer and the diffusion layer is set, and a thermal cycle model capable of satisfying the thermal cycle model is set. The surface of the product can be easily and easily heat-treated.

In particular, the deriving step S20 may further include a ratio setting step S21, a first securing step S22, a second securing step S23, a third securing step S24, and a fourth securing step S25 ). ≪ / RTI >

Specifically, in the ratio setting step S21, a ratio of the target thermal energy value of the compound layer to reach the target thickness and the target thermal energy value of the diffusion layer is set.

In the first securing step (S22), the target heat energy value of the compound layer is obtained through a thermal cycle model in which the relationship between the heating temperature and the heating time is formed.

In the second securing step S23, the thermal cycle model used in the first securing step S22 is substituted into the diffusion layer to obtain the target thermal energy value of the diffusion layer.

That is, after the ratio of the target heat energy value between the compound layer and the diffusion layer is set, the target thermal energy value of the compound layer is obtained through a thermal cycle model capable of securing the corresponding thermal energy value, and then the thermal cycle model is applied to the diffusion layer, It is possible to set a thermal cycle model satisfying the ratio of the target heat energy value between the compound layer and the diffusion layer.

However, in the third securing step (S24), when the heat energy value of the diffusion layer obtained in the second securing step (S23) does not coincide with the target heat energy value of the diffusion layer, the target heat energy value of the compound layer is changed to another heat cycle model .

In the fourth securing step (S25), the thermal cycle model used in the third securing step (S24) is substituted into the diffusion layer to obtain the target thermal energy value of the diffusion layer.

If the thermal cycle model that satisfies the ratio of the target thermal energy value between the compound layer and the diffusion layer is not obtained through the first securing step (S22) and the second securing step (S23), the third securing step (S24) And the fourth ensuing step (S25) can be repeatedly performed until the thermal energy value of the compound layer and the thermal energy value of the diffusion layer coincide with the target thermal energy value of the compound layer and the target thermal energy value of the diffusion layer.

The heat treatment of the heterogeneous material applied to the present invention is preferably a plasma nitriding heat treatment, and the product can be subjected to plasma nitriding heat treatment while ensuring the thickness of the nitrided layer of the compound layer and the diffusion layer through the plasma nitriding heat treatment.

Further, in the heat treatment step (S30) of the present invention, when the thermal energy values of the compound layer and the diffusion layer measured in real time are lower than the target thermal energy values of the compound layer and the diffusion layer, the plasma nitriding heat treatment of the material continues, Reaches the target heat energy value, the material can be cooled while completing the plasma nitriding heat treatment of the material.

The heat energy value can be calculated by the following equation (1) using the compound layer formation activation energy and the diffusion layer formation activation energy.

Equation 1

Here, in the case of the compound layer, T = absolute temperature, Q = activation energy of compound layer formation, R = gas constant, dt = heating holding time,

In the case of the diffusion layer, T = absolute temperature, Q = diffusion layer formation activation energy, R = gas constant, and dt = heating holding time.

The compound layer formation activation energy and the diffusion layer formation activation energy may be derived from the relationship between the thermal energy independently applied to the compound layer and the diffusion layer, the thickness of the compound layer, and the thickness of the diffusion layer. In some cases, Activation energy and diffusion layer formation activation energy may be applied.

Meanwhile, the surface heat treatment control apparatus according to the present invention can be configured to be controllable through the control unit 10. [

Specifically, a device for controlling the surface heat treatment so as to form a compound layer and a diffusion layer on a single material is formed by setting a target thickness of a compound layer and a diffusion layer, and setting a target thickness of the compound layer and the diffusion layer And the heat energy is applied to the single material and the heat energy is applied to the compound layer and the diffusion layer during the heat treatment to compare the target value of the target thermal energy with the real time heat energy value measured. And a control unit (10) for controlling the control unit (10).

Here, the control panel 12 connected to the controller 10 may be configured such that the current heat treatment temperature is displayed and visually confirmed, together with the numerical values of the compound layer and the diffusion layer thermal energy measured in real time and the target thermal energy value of the compound layer and the diffusion layer .

The operation and effect of the present invention will be described with reference to the accompanying drawings.

According to the surface heat treatment method of the present invention, a compound layer is formed at the outermost layer during the plasma nitridation heat treatment for a single material, and a diffusion layer whose hardness is increased by diffusion penetration of nitrogen is formed in the metal.

Specifically, when the compound layer and the diffusion layer are to be controlled simultaneously, heat treatment is performed under the same plasma gas atmosphere condition and various constant temperature holding conditions. As shown in the graph on the left side of FIG. 2, A growth curve is formed. At this time, if the x-axis is converted into the heat energy value using Equation (1), it results in a single curve like the right side.

That is, regardless of the heating rate or thermal history, there is a unique relationship between the thermal energy value applied to the product and the thickness of the compound layer thickness, so that by measuring the thermal energy applied to the product, this graph can be used to monitor the compound layer thickness in real time .

Here, the activation energy value of the compound layer formation substituted into the equation (1) is 259 kJ / mol.

A thickness growth test of the diffusion layer was carried out in the same manner as above to obtain a curve forming the relationship in which the thickness of the diffusion layer increases together with the increase of the heat energy value as shown in the right curve of Fig. At this time, the diffusion layer formation activation energy value is 112 kJ / mol.

That is, since the activation energy for forming the diffusion layer is about half of the activation energy for the formation of the compound layer, it can be predicted that the diffusion layer can grow more rapidly.

Using the fact that the activation energy for each phase is different when there are different phases in a single material as well, the plasma nitridation process is performed using the concept of the relative area ratio above the activation energy of each phase as shown in FIG. A thermal cycle model can be designed.

That is, when there is a target thickness of the compound layer and the diffusion layer, and the thermal energy for achieving the target thickness is designed as shown in FIG. 4, the heating and temperature heating conditions are simultaneously determined.

Taking FIG. 4 as an example, when the compound formation is minimized and the diffusion layer is maximized as in a tool, plasma nitridation treatment is performed at a temperature equal to or lower than the compound layer formation activation energy, so that the compound layer formation can be suppressed and only the diffusion layer can be formed. That is, the thickness of the diffusion layer can be adjusted by adjusting the time.

Further, in the plasma oxynitriding process for securing corrosion resistance, when a compound layer thickness of 10 mu m level is also required, a condition that a compound layer becomes 10 mu m under various heating conditions in which a diffusion layer of 300 mu m is formed, that is, So that the heat treatment can be designed. That is, the target two-layer thickness can be simultaneously achieved by appropriately adjusting the thermal cycle model (relative area ratio).

5 is an example of designing an actual thermal cycle model for the surface heat treatment of the present invention. When the target thickness of the diffusion layer is 100 탆 and the target thickness of the compound layer is desirably suppressed to the maximum of 5 탆 or less, Various heat treatment designs can be made at temperature. When the thickness of the diffusion layer is varied to 500 to 940 占 퐉 while keeping the compound layer constant at the level of 20 占 퐉, the thermal energy necessary for forming the diffusion layer, that is, Can be achieved by varying the relative area of the thermal cycle model.

Thus, by setting the target thermal energy value corresponding to the target thickness of the two layers by the designed thermal cycle model and comparing the thermal energy value applied up to the present time with the target thermal energy value by the formula 1, Can be monitored.

1, first, as a design step for achieving a target nitriding thickness of the compound layer and the diffusion layer, the surface heat treatment method is applied to the surface of the substrate, Derive a relationship. Then, the ratio of the thermal energy values of the two layers to reach the target nitriding thickness obtained in advance through the product performance test is set as the target.

Subsequently, the heat energy value of the compound layer is obtained by changing the thermal cycle model made up of temperature and time, and the heat cycle model is substituted to obtain the heat energy value of the diffusion layer.

If the thermal energy level of the diffusion layer differs from the target thermal energy value, the target thermal energy value of the compound layer is again obtained by substituting another thermal cycle model (heating time, heating temperature), and then the thermal cycle model is substituted into the diffusion layer, Is equal to the target heat energy value. The process is repeated until such a match is reached, and the actual plasma nitridation heat treatment is performed at the moment of coincidence.

Subsequently, the target thermal energy values of the designed compound layer and the diffusion layer are input to the controller 10, and then, during the actual heat treatment process, the thermal energy value applied to each layer in real time using Equation 1 is continuously compared with the target thermal energy value, During the heat treatment, the plasma heat treatment is terminated as soon as the heat energy value reaches the target heat energy value.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the specific embodiments set forth herein; rather, .

S10: Setting step S20: Deriving step
S21: ratio setting step S22: first securing step
S23: Second securing step S24: Third securing step
S25: Fourth ensuring step S30: Heat treatment step
10: Control unit 12: Control panel

Claims (10)

As a method for surface heat treatment so that a compound layer and a diffusion layer are laminated on a single material,
A setting step (S10) of setting a target thickness of the compound layer and the diffusion layer;
A derivation step (S20) of deriving a target heat energy value of the compound layer and the diffusion layer to reach a target thickness of the compound layer and the diffusion layer under a heat treatment condition for applying heat energy to the single material; And
And a heat treatment step (S30) of performing heat treatment while comparing the target thermal energy value with a real time thermal energy value measured by applying thermal energy to the compound layer and the diffusion layer when the heat treatment is applied to the single material by heat treatment. Heat treatment method. The method according to claim 1,
The derivation step (S20)
A ratio setting step (S21) of setting a ratio of a target thermal energy value of the compound layer and a target thermal energy value of the diffusion layer to reach the target thickness;
A first securing step (S22) of obtaining a target heat energy value of the compound layer through a thermal cycle model forming a relationship between a heating temperature and a heating time;
And a second securing step (S23) of substituting the thermal cycle model used in the first securing step (S22) into the diffusion layer to obtain a target heat energy value of the diffusion layer. 3. The method of claim 2,
A third securing step (S24) in which, when the heat energy value of the diffusion layer obtained in the securing step S23 does not coincide with the target heat energy value of the diffusion layer, the target heat energy value of the compound layer is changed to another thermal cycle model );
And a fourth securing step (S25) of substituting the thermal cycle model used in the third securing step (S24) into the diffusion layer to obtain a target thermal energy value of the diffusion layer. The method of claim 3,
The third securing step (S24) and the fourth securing step (S25) are repeated until the heat energy value of the compound layer and the heat energy value of the diffusion layer match the target heat energy value of the compound layer and the target heat energy value of the diffusion layer And the surface heat treatment is performed. The method according to claim 1,
Wherein the surface heat treatment is a plasma nitridation heat treatment. 6. The method of claim 5,
In the heat treatment step S30,
When the heat energy value measured in real time is lower than the target heat energy value, the plasma nitriding heat treatment of the material continues,
Wherein the material is cooled while terminating the plasma nitridation heat treatment of the material when the heat energy value measured in real time reaches a target heat energy value. The method according to claim 6,
Wherein the heat energy value is measured by the following formula (1) using the compound layer formation activation energy and the diffusion layer formation activation energy.
Equation 1

Where T = absolute temperature, Q = activation energy or diffusion layer formation activation energy, R = gas constant, dt = heating hold time. The method according to claim 6,
Wherein the compound layer formation activation energy and the diffusion layer formation activation energy are derived from the relationship between the thermal energy independently applied to the compound layer and the diffusion layer, the compound layer thickness and the diffusion layer thickness. An apparatus for controlling surface heat treatment so that a compound layer and a diffusion layer are laminated on a single material,
The target thickness of the compound layer and the diffusion layer is set and a target thermal energy value of the compound layer and the diffusion layer for reaching the target thickness of the compound layer and the diffusion layer is derived under the heat treatment condition for applying heat energy to the single material, And a controller (10) for controlling the heat treatment to be performed while comparing the measured real-time thermal energy value and the target thermal energy value measured by applying thermal energy to the compound layer and the diffusion layer during the heat treatment. 10. The method of claim 9,
Wherein the control panel (12) connected to the controller (10) is configured to visually confirm the thermal energy level of the compound layer and the diffusion layer measured in real time and the target thermal energy value of the compound layer and the diffusion layer.

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