KR100687799B1 - refrigerant-cycling and vertically-charged vacuum heat treatment furnace and method for vacuunm heat-treatment - Google Patents

Abstract

Refrigerant circulation type vertical vacuum heat treatment furnace configured to configure the vacuum heat treatment furnace by the vertical charging method, to cool the heated workpiece by the refrigerant circulation type, and to control the heating according to the degree of vacuum inside the container in which the workpiece is charged; A vacuum heat treatment method is disclosed. The chamber charges the workpiece vertically. The heating means is installed adjacent to the chamber to heat the workpiece loaded in the chamber. The container houses the chamber and the heating means therein and is filled with an inert cooling gas inside. A vacuum evacuation means evacuates the vessel to vacuum the interior of the vessel. A refrigerant circulation line is disposed outside of the chamber. The cooling device circulates the refrigerant through the refrigerant circulation line.

Vacuum heat treatment furnace, vertical charging

Description

Refrigerant-cycling and vertically-charged vacuum heat treatment furnace and method for vacuunm heat-treatment

1 is a plan view showing a conventional vacuum heat treatment furnace.

Figure 2 is a schematic front sectional view of a refrigerant circulation vertical vacuum heat treatment furnace according to a preferred embodiment of the present invention.

3 is a plan view of a portion of a refrigerant circulation vertical vacuum heat treatment furnace according to a preferred embodiment of the present invention;

Figure 4 is a schematic cross-sectional view showing a preferred embodiment of the refrigerant circulation vertical vacuum heat treatment furnace according to a preferred embodiment of the present invention.

5 is a schematic cross-sectional view of a heat exchanger of a vacuum heat treatment furnace according to the present invention.

6 is a relationship diagram showing a relationship with a control unit for controlling a heating means according to the present invention;

7 is a flowchart illustrating a vacuum heat treatment method according to the present invention.

8 is a schematic diagram showing the flow of the unmanned automation program according to the present invention.

※ Explanation of code for main part of drawing ※

10 container 10-1 inner wall

10-2 Outer wall 10-3 Opening door

11 chambers and 12 cases

13 Heating means 14 Refrigerant circulation lines

15 cooling system 15-1 heat exchanger

15-2 Forced refrigerant transport means 16 Thermometer fittings

17 thermometer 100 containers

111 Chamber 115 Chiller

116 Thermocouple Cover 610 Control

620 memory section 630 alarm section

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of vacuum heat treatment furnaces, and more particularly, to a low cost and high efficiency vacuum heat treatment furnace for minimizing the occupied area of a device and the use of cooling gas and achieving a high vacuum degree, and an unmanned heat treatment method using the same.

Vacuum heat treatment is usually used for high temperature heat treatment of metal materials which require high cost and high quality which are easy to oxidize. A typical vacuum heat treatment furnace in the related art includes a container 100 and a chamber 111 disposed therein and heated by heating means. In addition, a vacuum exhaust line for vacuuming the inside of the container is connected, and a cooling device 115 is connected to cool the workpiece after heating. Such a conventional vacuum heat treatment furnace is completely exhausted by using a vacuum exhaust line in the state in which the workpiece is charged for heat treatment. Subsequently, the object is heated in a completely exhausted state, followed by an inert cooling gas (for example, Ar gas or N _2). Cooling to the target temperature is carried out while flowing the gas) into the vessel.

However, such a conventional vacuum heat treatment furnace requires a high cost in various ways. For example, as can be seen in Figure 1, by adopting a method of loading the workpiece horizontally, the occupied area occupied by the equipment itself compared to the effective effective area of the class is not only large, but also above all expensive It is inefficient configuration and method to maximize the consumption of the cooling gas by performing cooling while continuously flowing the inert cooling gas of. In addition, the conventional vacuum heat treatment furnace is designed so that the heating proceeds after the complete vacuum evacuation, and thus the time required for evacuation is increased, and the evacuation time is changed according to the vacuum evacuation conditions, thereby reducing the cost of delaying the working time. It causes a rise. In addition, in order to measure the temperature of the chamber, a conventional vacuum heat treatment furnace uses an expensive thermocouple sensor through a thermocouple fitting part 116 to set a set point position to match the position of the heat treatment target product. The sensor used is expensive and has a problem in that frequent additional costs are generated because of fatigue characteristics that occur due to fatigue cracking when used for a long time.

As described above, the conventional vacuum heat treatment furnace is a horizontal charging method, which has a large occupancy area compared to its contents, and accordingly, the components constituting the installation, in particular, the vacuum pumps, piping, and cooling devices are enlarged, and thus the price of the equipment itself is high. . In addition, there are factors that increase the heat treatment cost depending on the conditions under which the vacuum heat treatment process is performed.

SUMMARY OF THE INVENTION The present invention has been made to improve the above-described prior art, and an object of the present invention is to provide a vacuum heat treatment furnace for constituting a vacuum heat treatment furnace by a vertical charging method and cooling the heated to-be-processed object by a refrigerant circulation type.

Another object of the present invention is to provide an unmanned automated vacuum heat treatment furnace and a vacuum heat treatment method capable of controlling the heating according to the degree of vacuum inside the container into which the object is loaded.

In the vacuum heat treatment furnace of the present invention, a vertical charging method is adopted, rather than a conventional horizontal method, in a method of charging a workpiece. This minimizes the occupied area of the plant and allows a small pump capacity of the vacuum device used therein to achieve a sufficiently high degree of vacuum. In addition, in order to shorten the heat treatment working time as much as possible, it was designed in such a way that the heating is started at the time when the vacuum degree out of the oxidative atmosphere of the metal material loaded with the vacuum degree in the vacuum exhaust inside the container. In addition, unlike the conventional apparatus for continuously flowing inert cooling gas during the cooling period, the vacuum heat treatment furnace of the present invention fills the cooling gas to form an atmosphere before cooling, and then circulates a refrigerant such as cooling water using the cooling device. That's the way. In addition, the vacuum heat treatment furnace of the present invention adopts a vertical type container to fix the thermocouple to fit the height of the product is inserted without the need to individually install the sensor directly in the vicinity of the product heat-treated using the convection heat inside the container. To check the temperature.

Refrigerant circulation vertical charging vacuum heat treatment furnace according to the present invention comprises: a chamber for vertical charging of the workpiece; Heating means installed adjacent to the chamber to heat the workpiece loaded in the chamber; a container accommodating the chamber and the heating means therein and filled with an inert cooling gas; Vacuum evacuation means for evacuating the vessel to vacuum the interior of the vessel; A refrigerant circulation line disposed outside the chamber; And a cooling device for circulating the refrigerant through the refrigerant circulation line.

Preferably, the heat treatment furnace is a refrigerant circulation vertical charging vacuum heat treatment furnace including an opening and closing door installed in the upper portion of the container.

Preferably, the container is a double wall of the inner wall and the outer wall, the refrigerant circulation line is a refrigerant circulation type vertical charging vacuum heat treatment furnace, characterized in that installed between the inner wall and the outer wall of the container.

In addition, preferably, at least two or more thermometer fittings arranged in the height direction of the chamber are disposed in the container, and the refrigerant circulation vertical cabinet is inserted into the chamber through the thermometer fitting. It is a vertical vacuum heat treatment furnace.

Further, preferably, the refrigerant circulation line is a refrigerant circulation type vertical charging vacuum heat treatment furnace, characterized in that the coil or pipe type.

Preferably, the cooling device is a refrigerant circulation type vertical charging vacuum heat treatment furnace, characterized in that it comprises a heat exchanger and a refrigerant forced conveying means.

Further, preferably, a heat treatment method using a refrigerant circulation type vertical charging vacuum heat treatment furnace, comprising: (i) vertical charging of a workpiece; (ii) operating the vacuum evacuation means; (iii) initiating heating at a time when the vacuum in the chamber leaves the oxidative atmosphere; (iv) filling the interior of the vessel with inert cooling gas; And (v) circulating the refrigerant in the refrigerant circulation line.

Further, preferably, the chamber for vertical charging of the workpiece; Heating means installed at a lower portion of the chamber to heat the workpiece to be charged in the chamber; A container incorporating said chamber and said heating means; Vacuum evacuation means for evacuating the inside of the container to make a vacuum state: a refrigerant circulation line for circulating the supplied refrigerant disposed to surround the chamber; A cooling device connected to the refrigerant circulation line to force circulation of the refrigerant; And a control unit for controlling the operation of the heating means according to a comparison result between the vacuum degree in the chamber and the oxidative atmosphere reference vacuum degree.

In addition, preferably, the heating means is a refrigerant circulation type vertical charging vacuum heat treatment furnace including a molybdenum heating element.

Preferably, the control unit operates the heating means when the vacuum degree inside the chamber is equal to or greater than the oxidative atmosphere reference vacuum degree and stops the operation of the heating means when the vacuum degree inside the chamber is less than the oxidative atmosphere reference vacuum degree. A refrigerant circulation type vertical vacuum heat treatment furnace.

Also, preferably, the refrigerant circulation type vertical vacuum heat treatment furnace further includes a memory unit for storing the oxidative atmosphere reference vacuum degree.

Preferably, the refrigerant circulation type vertical vacuum heat treatment furnace further includes an alarm unit for generating an alarm in response to a control signal from the control unit when the operation of the heating means is stopped.

Further, preferably, a heat treatment method using a refrigerant circulation vertical vacuum heat treatment furnace, comprising: (i) evacuating a chamber in which a workpiece is loaded vertically; (ii) determining whether the vacuum degree inside the chamber is equal to or greater than the oxidative atmosphere reference vacuum degree: (iii) controlling the heating of the workpiece according to the determination result of step (ii); (iv) cooling the inside of the heated chamber.

Also, preferably, the step (iii) heats the workpiece within the chamber when the degree of vacuum in the chamber is greater than or equal to the oxidative atmosphere reference vacuum level, and when the degree of vacuum in the chamber is less than the oxidative atmosphere reference vacuum degree. It is a heat treatment method comprising the step of stopping the heating operation of the treatment.

Also, preferably, when the heating operation of the workpiece is stopped, the method further comprises generating an alarm.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 to 4 is a view showing a preferred embodiment of the vacuum heat treatment furnace according to the present invention, Figures 2 and 4 is a schematic cross-sectional view, Figure 3 is a plan view cut in part. 5 is a schematic cross-sectional view showing the internal structure of the heat exchanger of the refrigerant circulation vertical vacuum heat treatment furnace according to the present invention. 6 to 8 are diagrams illustrating a refrigerant circulation type vertical vacuum heat treatment furnace and a heat treatment method to which an automated program is applied, and FIG. 6 is a relationship diagram showing a relationship with a control unit for controlling a heating means, and FIG. 8 is a flowchart illustrating a heat treatment method to which the automated program of the present invention is applied, and FIG. 8 is a schematic diagram illustrating a flow of an unmanned automated program according to the present invention.

(Example)

The vacuum heat treatment furnace of the first preferred embodiment of the present invention includes a container 10 (shell) composed of double walls of the inner wall 10-1 and the outer wall 10-2 and sealing the interior. The opening / closing door 10-3 of a container is arrange | positioned at the upper surface part of a container. That is, unlike the conventional apparatus for opening and closing horizontally, it is installed in the upper portion of the container and vertically charged up and down. This configuration has the effect of substantially reducing the occupied area of the equipment by reducing the use of planar space and using the space above the equipment which is normally left unused. A refrigerant circulation line is disposed between the inner wall 10-1 and the outer wall 10-2 of the vessel, which will be described in detail below.

An inner container includes a case 12 defining a chamber 11, in which an object to be processed is placed. The workpiece placed in the chamber is heated by heating means 13 such as an electric heater.

The vessel 10 is connected with a vacuum evacuation means, such as a vacuum pump, for performing evacuation to evacuate the interior, and a cooling gas supply means for supplying an inert cooling gas such as Ar or N2 into the vessel.

In addition, the vacuum heat treatment furnace of the present invention includes a coil type refrigerant circulation line 14 disposed to surround the circumference of the case 12. The coiled refrigerant circulation line 14 is preferably disposed between the inner wall 10-1 and the outer wall 10-2 of the container 10. The refrigerant circulation line 14, which may be configured as a pipe, is connected to a cooling device 15 disposed outside. As can be seen in FIG. 3, the cooling device 15 comprises a heat exchanger 15-1 and a refrigerant forced transfer means 15-2 such as a blower. In this way, the cooling system of the vacuum heat treatment furnace of the present invention consisting of the refrigerant circulation line 14 and the cooling device 15 adopts a cooling method different from the conventional device. For example, the conventional apparatus is a method of injecting an expensive cooling gas such as Ar or N2 through the nozzle and the like continuously flowing while circulating the fan during the cooling period of the workpiece, but the cooling system of the vacuum heat treatment furnace of the present invention Cooling is performed by forcibly circulating the refrigerant by using the heat exchanger 15-1 and the refrigerant forced transfer means 15-2 of the cooling device 15 in a state where the inert cooling gas is pressurized into the container. This makes it possible to use an appropriate amount of expensive cooling gas that is excessively consumed excessively, and thus a significant cost reduction effect can be obtained.

In addition, at least two or more, preferably upper, middle, and lower three thermometer mouths 16 arranged in the height direction of the chamber 11 are disposed in the container, and a thermometer inserted into the chamber 11 through the chamber 11 is provided. Reference numeral 17 denotes a temperature measurement using convective heat inside the chamber, and the vacuum heat treatment furnace of the present invention is possible because it is a vertical charging type. Unlike conventional devices which extend several thermocouple sensors through one inlet to the desired measuring point, the vacuum heat treatment furnace of the present invention uses an inexpensive thermometer 17 through two or more inlets 16 properly arranged. By doing so, it is possible to obtain a comparable effect at low cost.

In the heat treatment method using the vacuum heat treatment furnace of the present invention, after the object to be processed is charged into the chamber 11, the vacuum exhaust means is operated to start evacuation.

The heating is then initiated by the heating means 13 at a time when the degree of vacuum inside the vessel leaves the oxidizing atmosphere, such as about 9.0 × 10 ⁻³ torr or more. Unlike the conventional apparatus which starts heating in a state of complete vacuum evacuation, it is possible to shorten the working time by initiating heating once the atmosphere inside the container reaches a degree of vacuum outside the oxidizing atmosphere.

Continue with the cooling step. The cooling step includes pressurizing and filling the inside of the container with an inert cooling gas such as Ar or N _2, and then circulating a refrigerant such as cooling water into the refrigerant circulation line 14 using the cooling device 15 in that state. do.

According to another preferred embodiment of the present invention, a low cost, high efficiency vacuum heat treatment furnace includes a vessel, a chamber, a heating means, a case, a refrigerant circulation line, a cooling device, and a control part, wherein the container seals the interior of the low cost, high efficiency vacuum heat treatment furnace. . The chamber is placed in the container to load the workpiece. The heating means heats the loaded workpiece. The case is disposed within the container to define the chamber. The refrigerant circulation line is arranged to surround the case. The cooling device circulates the refrigerant to the refrigerant circulation line for cooling the workpiece. The control unit controls the operation of the heating means according to the comparison result of the vacuum degree inside the chamber with the reference degree of oxidative atmosphere.

The heating means of the low cost high efficiency vacuum heat treatment furnace includes a molybdenum heating element.

In the case of the heating element used in the present invention, by using a molybdenum heating element other than the conventional graphite, it is possible to prevent contamination from carbon exposed to high temperature while the internally charged product is heat treated, Maintenance costs due to breakage can be reduced. In addition, molybdenum may be oxidized when exposed to oxygen at a temperature of 400 ° C. or higher, but in the present invention, if an appropriate level of vacuum is not obtained at 200 ° C. or higher by applying an unmanned automation program, the operation does not proceed and alarm is generated. It is designed to ring and is designed to suppress the damage caused by the oxidation of molybdenum.

In addition, the refrigerant circulation vertical vacuum heat treatment furnace of the present invention further includes a control unit 610, a memory unit 620, an alarm unit 630 in order to apply the unmanned automation program, the control unit of the refrigerant circulation vertical vacuum heat treatment furnace In operation 610, when the vacuum degree in the chamber is equal to or higher than the oxidative atmosphere reference vacuum degree, the heating means is operated. When the vacuum degree in the chamber is lower than the oxidative atmosphere reference vacuum degree, the operation of the heating means is stopped, and the operation of the heating means is stopped. When the oxidative atmosphere reference vacuum degree is stored, the memory unit 620 stores the oxidative atmosphere reference vacuum degree, and the control unit compares the vacuum in the chamber with the oxidative atmosphere reference vacuum degree and controls the alarm unit 630. Raise an alarm in response.

A heat treatment method using a low cost, high efficiency vacuum heat treatment furnace according to another embodiment: A workpiece is charged into a chamber. The chamber is evacuated by operating the vacuum evacuation means. After charging the to-be-processed object to the chamber 11, evacuation is started by operating a vacuum exhaust means.

Next, heating is initiated by the heating means 13 at a time when the degree of vacuum inside the vessel leaves the oxidizing atmosphere, such as about 9.0 × 10 ⁻³ torr or more. This is different from the conventional apparatus in which heating is started in a state of complete vacuum evacuation, and thus, the heating time can be shortened by initiating heating once the atmosphere inside the container reaches the degree of vacuum out of the oxidizing atmosphere. By starting the heating, an unmanned automated program can be executed to determine whether the vacuum in the chamber is equal to or higher than the oxidative atmosphere reference vacuum, ensuring the vacuum at the same time as heating, and suppressing the damage caused by the oxidation of molybdenum. According to the result of the determination, the heating of the chamber is controlled. Cooling the inside of the heated chamber.

Heating the chamber when the vacuum degree inside the chamber is equal to or higher than the oxidative atmosphere reference vacuum degree, and stopping the heating operation of the chamber when the vacuum degree inside the chamber is lower than the oxidative atmosphere reference vacuum degree, wherein the heating operation of the chamber is stopped. If so, further comprising the step of generating an alarm.

 The invention has the following effects.

(1) By adopting the vertical charging method from the existing horizontal charging method, the footprint of the equipment and the size of the vacuum exhaust system are minimized.

(2) Minimize consumption by using expensive inert cooling gas by designing by circulating the refrigerant after filling the cooling gas into the container instead of continuously flowing expensive cooling gas during cooling.

(3) The working time is shortened by starting the heating at a vacuum degree outside the oxidizing atmosphere of the charge material, rather than the method of completely heating the inside of the container after heating.

(4) As a vertical type, it is possible to measure temperature using convective heat in the furnace, so that an inexpensive general thermometer can be used, and the replacement method can also be performed at an external terminal, thereby providing convenience of replacement work.

(5) The manufacturing cost of the vacuum heat treatment furnace can be greatly reduced.

(6) The operator's management is reduced through the unmanned work program, and it is designed to contribute to the malfunction and safety of the machine by making the alarm handling device through the interlock device in case of an error.

Claims (17)

A chamber for vertically charging the workpiece; Heating means installed adjacent to the chamber to heat the workpiece to be charged in the chamber; A container accommodating the chamber and the heating means therein and filled with an inert cooling gas; Vacuum evacuation means for evacuating the vessel to vacuum the interior of the vessel; A refrigerant circulation line disposed outside the chamber; And And a cooling device for circulating the refrigerant through the refrigerant circulation line. 2. The refrigerant circulation vertical charge vacuum heat treatment furnace according to claim 1, further comprising cooling gas supply means for supplying the cooling gas into the container through the vacuum exhaust means. The refrigerant circulation type vertical vacuum heat treatment furnace according to claim 1, further comprising an opening and closing door installed at an upper surface of the container. The coolant circulation type vertical vacuum heat treatment furnace according to claim 1, wherein the container is a double wall of an inner wall and an outer wall, and the refrigerant circulation line is installed between the inner wall and the outer wall of the container. According to claim 1, wherein at least two or more thermometers arranged in the height direction of the chamber is arranged in the container, the refrigerant circulation type vertical vacuum, characterized in that the thermometer is inserted into the chamber through the thermometer openings. Heat treatment furnace. The refrigerant circulating vertical vacuum heat treatment furnace according to claim 1, wherein the refrigerant circulation line is a coil type or a pipe type. The refrigerant circulating vertical vacuum heat treatment furnace according to claim 1, wherein the cooling device includes a heat exchanger and a refrigerant forced conveying means. (i) vertical loading of the workpiece into the container; (ii) evacuating the vessel to vacuum the interior of the vessel; (iii) initiating heating at a time when the vacuum degree inside the vessel leaves the oxidizing atmosphere; (iv) filling with an inert gas into the vacuum vessel; And (v) circulating a refrigerant in a refrigerant circulation line. A chamber for vertically charging the workpiece; Heating means installed adjacent to the chamber to heat the workpiece to be charged in the chamber; A container accommodating the chamber and the heating means therein and filled with an inert cooling gas; Vacuum evacuation means for evacuating the vessel to vacuum the interior of the vessel; A refrigerant circulation line disposed outside the chamber; A cooling device for circulating a refrigerant through the refrigerant circulation line; And Refrigerant circulation type vertical vacuum heat treatment furnace including a control unit for controlling the operation of the heating means in accordance with the comparison result of the vacuum degree in the vessel and the oxidative atmosphere reference vacuum degree. The refrigerant circulating vertical vacuum heat treatment furnace according to claim 9, wherein the oxidative atmosphere reference vacuum degree is a vacuum degree inside the container when the inside of the container leaves the oxidative atmosphere. 10. The refrigerant circulation type vertical vacuum heat treatment furnace according to claim 9, wherein said heating means comprises a molybdenum heating element. 10. The method of claim 9, wherein the control unit operates the heating means when the vacuum degree inside the container is equal to or higher than the oxidative atmosphere reference vacuum degree and stops the operation of the heating means when the vacuum degree inside the container is lower than the oxidative atmosphere reference vacuum degree. Refrigerant circulation type vertical vacuum heat treatment furnace. The refrigerant circulating vertical vacuum heat treatment furnace of claim 9, further comprising a memory unit configured to store the oxidative atmosphere reference vacuum degree. The refrigerant circulating vertical vacuum heat treatment furnace according to claim 12, further comprising an alarm unit that generates an alarm in response to a control signal from the control unit when the operation of the heating means stops. (i) evacuating the container in which the workpiece is loaded vertically in a vacuum state; (ii) determining whether the degree of vacuum in the vessel is equal to or greater than the oxidative atmosphere reference vacuum degree: (iii) controlling the heating of the workpiece charged into the chamber according to the determination result of step (ii); (iv) filling an inert cooling gas into the vacuum vessel; And (v) circulating a refrigerant in a refrigerant circulation line formed in the vessel. The method of claim 15, wherein step (iii) is to heat the workpiece when the degree of vacuum in the vessel is equal to or greater than the oxidative atmosphere reference vacuum degree, and when the degree of vacuum in the vessel is less than the oxidative atmosphere reference vacuum degree, heating the workpiece. A vacuum heat treatment method comprising the step of stopping the operation. The vacuum heat treatment method according to claim 16, further comprising generating an alarm when the heating operation of the workpiece is stopped.

Images