JPH0255486B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a one-chamber vacuum heat treatment furnace, and more specifically, it heats a workpiece such as steel material under vacuum and then heat-treats it using gas cooling. Regarding vacuum heat treatment furnaces.

<Prior art> In a conventional vacuum heat treatment furnace using this type of single-chamber gas cooling, a pressure reducing device and a cooling gas supply device are connected to a vacuum container, a heating chamber is arranged inside the vacuum container, A circulation device for circulating the supplied cooling gas is disposed around the heating chamber within the vacuum container.

Conventional vacuum heat treatment furnaces of this type include the following two types depending on the gas cooling method.

(1) In the first type, the heating chamber has a substantially rectangular parallelepiped shape, and in addition to an internal door provided at the front for loading and unloading the processed material, cooling doors are provided on the top and bottom walls of the heating chamber. This type further includes a cooling fan as a circulation device in the vacuum container above the heating chamber. When cooling this type of workpiece, both the upper and lower cooling doors are opened and the cooling fan is activated, allowing the cooling gas to flow in only one direction, from top to bottom or from bottom to top. was used to cool the object to be processed.

(2) The second type has a cylindrical heating chamber placed horizontally in the front and back, and has cooling doors on the front and rear walls of the heating chamber (the cooling door on the front wall also serves as a way to take in and take out the processed material). Furthermore, a plurality of blowout nozzles for blowing out cooling gas along the circumferential direction are provided on the inner peripheral surface of the heating chamber, and each of these blowing nozzles is connected to a duct extending from a blower serving as a cooling gas circulation device. When cooling this type of workpiece, both the front and rear cooling doors are opened, the blower is operated, and cooling gas is blown onto the workpiece from all or predetermined blow-off nozzles, radially inward in the heating chamber. After that, the object to be processed is cooled by using the flow of cooling gas directed toward the front and rear of the heating chamber.

<Problems to be Solved by the Invention> In the first type of furnace, the flow of cooling gas in only one direction from above to below or from below to above is used, and the material to be processed is formed in the form of a long and thin rod. If the workpiece is in the form of a thin plate, it can be suspended vertically, and if the workpiece is in the form of a thin plate, it can be stood upright for uniform quenching.

However, when the workpiece is a thick, large workpiece such as a substantially spherical, substantially cubic, or rectangular parallelepiped, the upper and lower parts of the workpiece are cooled by separating the upstream and downstream sides of the cooling gas. The speeds were significantly different, and large quenching distortions were likely to occur in the workpiece, making it unsuitable for heat treatment in the first type of furnace.

Note that this drawback is the same when heat treatment is performed in the second and third stages, and the cooling rate of the processed material on the downstream side of the cooling gas on either the upper stage or the lower stage becomes slow, and the The quenching of the workpiece in the downstream direction was insufficient, and it was difficult to heat treat it in the first type of furnace.

In addition, the second type of furnace utilizes the flow of cooling gas that passes through the blow-off nozzle on the heating chamber's peripheral wall, radially inward from the heating chamber's peripheral wall, hits the workpiece, and then heads toward the front and back of the heating chamber. Therefore, when the object to be processed is a large, thick-walled object such as a substantially spherical, substantially cubic, or substantially rectangular parallelepiped, quenching can be performed satisfactorily.

However, in this type of furnace, as mentioned above,
The cooling gas blown out from the blow-off nozzle inward in the radial direction of the heating chamber always ends up flowing in two directions in the front and back directions of the heating chamber, so the flow of the cooling gas in the front and back directions of the heating chamber overlaps with the object to be processed. That is unavoidable. Therefore, when heat treating a long, slender rod-shaped workpiece, no matter how it is set in the furnace, bow-shaped quenching distortion will occur in the workpiece, making it unsuitable for heat treatment in the second type of furnace. It was hot.

In particular, in recent years, with the use of turbo fans and the development of pressurized gas cooling, it has become possible to obtain faster gas cooling rates, and as the cooling rates are becoming faster and faster, the above-mentioned problem of quenching distortion has been solved. It is becoming more likely to occur.

This invention can solve the above problems,
Even if the shape, size, etc. of the workpiece changes, the flow of cooling gas can be changed appropriately, and the workpiece can be cooled at a uniform rate, allowing heat treatment to be performed while minimizing the occurrence of quenching distortion. The purpose of the present invention is to provide a vacuum heat treatment furnace that can perform the following steps.

<Means for Solving the Problems> In the vacuum heat treatment furnace according to the present invention, a pressure reducing device and a cooling gas supply device are connected to a vacuum container, and a heating chamber and a predetermined position around the heating chamber are provided in the vacuum container. A vacuum heat treatment furnace is equipped with a circulation device that is arranged in a vacuum chamber to circulate the supplied cooling gas within the vacuum vessel, the heating chamber is approximately rectangular parallelepiped-shaped, and the cooling gas discharge side of the circulation device is provided with a cooling gas discharge side. , each equipped with a damper that can be opened and closed independently, and connected to four ducts each having a blow-off nozzle at the tip, and each blow-off nozzle is connected to the top wall, bottom wall, and left and right side walls of the heating chamber, respectively. The top wall, bottom wall, left and right side walls facing the blow-off nozzle in the heating chamber, and the front wall and rear wall, which are arranged facing each other with a gap, can be opened and closed independently. It is characterized by being equipped with a possible cooling door.

<Operations and Effects of the Invention> In the vacuum heat treatment furnace according to the present invention, after the workpiece is vacuum heat-treated, cooling gas from the cooling gas supply device is supplied into the vacuum container, and the upper and bottom walls of the heating chamber are heated. The cooling doors on the left and right side walls are opened, and the cooling doors on the front and rear walls of the heating chamber are also opened. At the same time, if the circulation device is operated and a predetermined damper is opened, cooling gas is blown out from a predetermined blow-off nozzle through a duct, and the cooling gas flows into the heating chamber from the wall of the predetermined heating chamber. Ru. After that, the cooling gas that has flowed in cools the object to be processed, and then flows out of the heating chamber from the wall of the heating chamber, which is open without the flow of cooling gas, and is taken into the circulation device and circulated again.

That is, in the vacuum heat treatment furnace according to the present invention,
By arbitrarily opening and closing the cooling doors on the top and bottom walls and left and right side walls of the heating chamber, and operating the damper to blow out the cooling gas from the blow-off nozzles facing those walls. , the cooling gas can be introduced from any direction such as above, below, left, or right inside the heating chamber. If the other cooling door of the heating chamber is left open, the inflowing cooling gas can flow out in any direction other than the direction of inflow, including the front, rear, upper, lower, left, and right of the heating chamber. be able to.

Therefore, in the vacuum heat treatment furnace according to the present invention, the flow of the cooling gas can be changed as appropriate, so even if the shape, size, etc. of the workpiece changes, cooling can be performed in accordance with the workpiece. It can be cooled by gas flow, and the object to be processed can be cooled at a uniform rate.
It is possible to suppress the occurrence of quenching distortion as much as possible.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

As shown in FIGS. 1 to 3, the vacuum heat treatment furnace F of the embodiment includes a vacuum container 1 connected to a known pressure reducing device 2 and a cooling gas supply device 3 such as nitrogen gas, and a heating chamber in the vacuum container 1. 4 are arranged. Vacuum container 1
The front part is a charging door 1A for charging the workpiece M into the inside.
It is said that

The heating chamber 4 has a substantially rectangular parallelepiped shape, includes a known heating element (not shown), and is surrounded by a known heat insulating material. The heating chamber 4 has an upper wall 4A, a bottom wall 4B,
Left side wall 4C, right side wall 4D, front wall 4E, and rear wall 4
F, cooling doors 8A, 8B, 8C, 8D, 8 which are selectively opened when cooling the object to be processed M, respectively.
E, equipped with 8F. Each cooling door 8A to 8F
can be opened and closed independently by an opening/closing device using an air cylinder (not shown) or the like arranged outside the vacuum container 1. Note that the cooling door 8E of the front wall 4E also serves as a function for loading the object M to be processed. Further, 4a is a stand for the object M to be processed.

A circulation device 5 including a fan, a blower, etc., that circulates the cooling gas supplied by the cooling gas supply device 3 within the vacuum container 1 is disposed behind the heating chamber 4 . The intake side of this circulation device 5 is located at one place behind the heating chamber 4, as shown in FIG. It is connected and branched into four parts. The circulation device 5 also includes a known cooling means (not shown) that cools the circulating cooling gas.

Each duct 6A, 6B, 6C and 6D has a damper 7A, 7B, 7C on the base side as shown in FIG.
and 7D. Each duct 7A to 7D is
Each can be opened and closed independently by an opening/closing device using an air cylinder (not shown) placed outside the vacuum container 1.

Further, the tip side of each duct 6A to 6D is connected to the first,
As shown in Figure 2, the upper wall 4A and the bottom wall 4 of the heating chamber 4
B, and cooling doors 8 on the left and right side walls 4C and 4D
It extends to the open parts A to 8D. Blowout nozzles 9A, 9B, 9C, and 9D each have a plurality of discharge holes and are disposed facing each other with a gap between them and the respective wall portions 4A to 4D.
is located.

Next, the manner in which the furnace F of this embodiment is used will be explained.

First, a case will be described in which a thin plate-shaped object to be processed M1 is heat-treated. Incidentally, when the objects to be processed M1 are in the shape of a thin plate, it is preferable to stand the plurality of objects to be processed M1 and to flow the cooling gas in the vertical direction, considering the amount of processing.

First, the charging door 1A and the cooling door 8E on the front wall 4E of the heating chamber are opened, and a plurality of workpieces M are placed inside the heating chamber 4.
1 is placed upright and charged, and the charging door 1A and the cooling door 8E are closed.

Then, the pressure reducing device 2 is operated, and the vacuum container 1 is
The interior is brought into a vacuum state and the object to be processed M1 is heated.

After the object to be processed M1 is maintained at a predetermined temperature for a predetermined time, the cooling gas supply device 3 is activated to pressurize the inside of the vacuum container 1 with the cooling gas. At the same time, the cooling doors 8A and 8B on the heating chamber top and bottom walls 4A and 4B
Then, the damper 7A of the duct 6A communicating with the upper wall 4A is opened, and the circulation device 5 is activated.

Then, the cooling gas flows into the heating chamber from the upper wall 4A through the blow-off nozzle 9A and flows out from the bottom wall 4B.
After that, it is sucked into the circulation device 4, passes through the duct 6A, flows into the heating chamber 4 from above again from the blow-off nozzle 9A, and is circulated (see Figs. 1 to 4).

After that, the damper 7A is closed, and the damper 7B of the duct 6B communicating with the bottom wall 4B is opened.

Then, the cooling gas flows in from the bottom wall of the heating chamber through the blow-off nozzle 9B, flows out from the top wall 4A, and then circulates through the circulation device 5 (fifth
(see figure).

The cooling gas flowing from above to below or from below to above within these heating chambers 4 cools each part of the thin plate-shaped workpiece M1 at a uniform cooling rate, thereby reducing the occurrence of quenching distortion. It will be hardened.

After that, once the quenching process has been completed, the circulation device 5 is stopped, and the charging door 1A and the front wall 4E of the heating chamber are opened.
The cooling door 8E may be opened and the object to be processed M1 may be taken out.

Next, to explain the case where the workpiece M2 is heat-treated in two or three stages, etc., when cooling, both the cooling doors 8C and 8D on the left and right side walls 4C and 4D of the heating chamber are opened, and the left side wall The circulation device 5 may be operated by sequentially and alternately opening the damper 7C of the duct 6C leading to the duct 4C and the damper 7D of the damper 6D leading to the right side wall 4D.

Then, as shown in FIGS. 6 and 7, the cooling gas flows into the heating chamber 4 from the left side wall 4C through the blowout nozzle 9C, flows out from the right side wall 4D, and circulates, or flows through the blowout nozzle 9D into the right side wall. It flows into the heating chamber 4 from 4D, flows out from the left side wall 4C, and is circulated.

Therefore, each of the stacked workpieces M2 can be uniformly cooled, and the workpieces M2 can be hardened while suppressing the occurrence of hardening distortion.

Furthermore, when heat-treating the thick and large spherical plate M3, each wall 4A of the heating chamber 4 is heated during cooling.
4F and 7D to each damper 7A of each duct 6A to 6D are all opened to operate the circulation device 5.

Then, as shown in FIGS. 10 and 11, the cooling gas passes through each blow-off nozzle 9A to 9D and reaches the upper wall 4A, the bottom wall 4B, and the left and right side walls 4C, 4 all around the heating chamber 4.
It flows in from D, flows out from the front and rear walls 4E and 4F, and circulates.

Therefore, similar to the second type of furnace described in the conventional technology section, it is possible to
can be uniformly cooled, and the workpiece M3 can be hardened while suppressing the occurrence of hardening distortion.

Furthermore, if desired, the heating chamber front and rear walls 4E, 4
With each wall 4A to 4D except for F open,
The ducts 7A and 7B of the ducts 6A and 6B leading to the top and bottom walls 4A and 4B are opened, and the left and right side walls 4
Damper 7 of duct 6C, 6D passing through C, 4D
C, 7D may be opened and the circulation device 5 may be operated.

In this embodiment, the cooling gas is
As shown in FIG. 9, the water flows into the heating chamber 4 from above and below and flows out from the left and right, or flows into the heat chamber 4 from the left and right and flows out from the top and bottom.

Therefore, in the vacuum heat treatment furnace F of the example, the cooling doors 8A to 8F and the dampers 7A to 7D are operated,
A fourth method that combines the flow of cooling gas in the heating chamber 4 during cooling in the vertical direction, left-right direction, front-back direction, etc.
In addition to the seven basic shapes shown in Figures 1 to 10, various flows can be selected.

Therefore, even if the shape, size, etc. of the object to be processed changes, the flow of cooling gas can be changed appropriately, so the object can be cooled with a flow of cooling gas that corresponds to the object to be processed. It has the same effect as described in the function/effect section.

In addition, in the furnace F of the example, each cooling door 8A
The operations of ~8F and dampers 7A to 7D can be adjusted using a controller, etc., and for example, the seven basic shapes shown in Figures 4 to 10 can be configured automatically, including the time, to process the same or different types of objects. The object M can also be subjected to vacuum heat treatment by automatic operation according to various patterns.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the − portion of FIG. 1 in the same embodiment, and FIG. 3 is a cross-sectional view showing the − portion of FIG. 1 in the same embodiment. Cross-sectional view, Figure 4, Figure 5, Figure 6
7, 8, 9, and 10 are schematic cross-sectional views when variously changing the flow of cooling gas during cooling, respectively, and FIG.
It is a schematic sectional view showing a - part of a figure. 1... Vacuum container, 2... Pressure reducing device, 3... Cooling gas supply device, 4... Heating chamber, 4A... Upper wall, 4
B...bottom wall, 4C...left wall, 4D...right wall,
4E...Front wall, 4F...Rear wall, 5...Circulation device,
6A, 6B, 6C, 6D...Duct, 7A, 7
B, 7C, 7D...Damper, 8A, 8B, 8C,
8D, 8E, 8F...Cooling door, 9A, 9B, 9
C, 9D...Blowout nozzle, F...Vacuum heat treatment furnace,
M, M1, M2, M3... objects to be processed.

Claims (1)

[Scope of Claims] 1 A vacuum container is connected to a pressure reducing device and a cooling gas supply device, and within the vacuum container is a heating chamber and a cooling gas disposed at a predetermined position around the heating chamber. A vacuum heat treatment furnace is provided with a circulation device for circulating gas in the vacuum container, wherein the heating chamber has a substantially rectangular parallelepiped shape, and each cooling gas discharge side of the circulation device can be opened and closed independently. four ducts each having a blow-off nozzle at the tip thereof are connected, and each blow-off nozzle has a gap with respect to the top wall, the bottom wall, and the left and right side walls of the heating chamber, respectively. The top wall, the bottom wall, and the left and right side walls facing the blow-off nozzle in the heating chamber, and the front wall and the rear wall are each provided with a cooling device that can be opened and closed independently. A vacuum heat treatment furnace characterized by being provided with a door.