JP2586480B2 - Vacuum heat treatment furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a vacuum heat treatment furnace.

Vacuum heat treatment furnaces are used when various materials to be heated are vacuum-heated and gas cooled. For example, there is a case where a metal material such as a mold and a tool is hardened by vacuum heating and gas cooling. In general, a vacuum heat treatment furnace of this type has a heating chamber surrounded by a heat insulating material formed in a furnace body, a heat exchanger, a fan, and the like are provided in the furnace body, and a heater is provided in the heating chamber. After heating the material to be heated in the heating chamber in vacuum, the cooling gas introduced into the heating chamber is cooled by a heat exchanger and circulated by a fan to cool the gas. In such a vacuum heat treatment furnace, a nozzle is inserted into the heating chamber through a heat insulating material forming a heating chamber in order to speed up cooling of the material to be heated after vacuum heating, and a cooling gas is supplied from the nozzle. There are some types that erupt.

The present invention relates to an improvement in a vacuum heat treatment furnace of the type in which a cooling gas is jetted from a nozzle as described above.

<Prior art and its problems> Conventionally, as a vacuum heat treatment furnace in which a nozzle is inserted into the heating chamber through a heat insulating material forming the heating chamber, the nozzle is fixed to face the central axis of the furnace body. The ones that are regularly arranged are used.

However, according to such a conventional furnace, there is a problem that, depending on the shape of the material to be heated, distortion occurs in the material to be heated after the vacuum heat treatment. In particular, the occurrence of such distortion is remarkable when a small object such as a drill is subjected to a vacuum heat treatment.

<Problems to be solved by the invention and means for solving them> The present invention provides an improved vacuum heat treatment furnace that solves the above-mentioned conventional problems.

Thus, the present inventors have studied from the above viewpoint. As a result, in order to reduce the occurrence of distortion in the material to be heated after the vacuum heat treatment, the injection of the cooling gas corresponding to the shape of the material to be heated is performed. It is important to change the direction, for example, for small objects such as drills, a vacuum is applied from the nozzle as in the conventional furnace in which the nozzle is fixedly arranged facing the central axis of the furnace body. It has been found that it is important not to eject the cooling gas in a relationship perpendicular to the drill after heating, but to eject the cooling gas in a relationship parallel to the drill.

That is, according to the present invention, a heating chamber surrounded by a heat insulating material is formed in a furnace main body, and after a material to be heated is vacuum-heated in the heating chamber, a cooling gas cooled by a heat exchanger is circulated to circulate the gas. In a vacuum heat treatment furnace for cooling, a plurality of pipes for introducing a cooling gas into a heating chamber are arranged in parallel between a furnace body and a heat insulating material forming a heating chamber, and the heat insulating material is provided in each of the pipes. A plurality of nozzles inserted through the heating chamber and inserted into the heating chamber. Attachments for regulating the jetting direction of the cooling gas are attached to the respective tips of the nozzles, and the jetting of the cooling gas is performed by the attachment. The present invention relates to a vacuum heat treatment furnace configured to change the direction.

In the vacuum heat treatment furnace according to the present invention, as in the case of the conventional furnace, a heating chamber surrounded by a heat insulating material is formed in the furnace body, and a heat exchanger, a fan, and the like are provided in the furnace body.
Further, a heating source is provided in the heating chamber, and a vacuum pump for making the heating chamber a vacuum atmosphere is connected to the furnace body.

In the vacuum heat treatment furnace according to the present invention, a plurality of pipes are arranged in parallel between the furnace body and a heat insulating material forming a heating chamber.
Usually, these pipes are arranged side by side at predetermined intervals in a ring shape as a whole in the furnace length direction around a heat insulating material forming a heating chamber. These pipes serve as a circulation path (outward path) of a cooling gas that is cooled by the heat exchanger and circulated by the fan. Each of these pipes is provided with a plurality of nozzles inserted through the heat insulating material forming the heating chamber and inserted into the heating chamber. Attachments are attached to tips of the nozzles. The attachment regulates the direction in which the cooling gas introduced through the pipe and the nozzle is ejected into the heating chamber. For example, an attachment made of a cylindrical part having an inclined portion is slid on the outer periphery of the tip of each nozzle, and these attachments are screwed to the outer periphery of the tip of each nozzle. The cooling gas is ejected in the direction in which the cooling gas is directed.

According to the present invention, by adjusting the direction in which each of the attachments is directed in advance according to the shape of the material to be heat-treated, the cooling gas is applied to the material to be processed after vacuum heating from an appropriate direction according to the shape. Can be spouted,
A high-quality heat-treated product with little distortion can be obtained.

Hereinafter, the configuration of the present invention will be described in more detail with reference to the drawings.

<Embodiment> FIG. 1 is a cross-sectional view of a main part in a furnace length direction showing an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of a main part in a furnace width direction showing the same embodiment as FIG. . Furnace body 21 with openable door 11
A heating chamber 32 surrounded by a heat insulating material 31 is formed therein,
The furnace body 21 is provided with a heat exchanger 41 and a fan 51, and the fan 51 is connected to a motor 52 installed outside the furnace.
The heating chamber 32 has openings 33, 34 on both sides in the furnace length direction.
34 is equipped with doors 12 and 13 that can be opened and closed. When the door 12 is opened, the heating chamber 32 communicates with the inside of the furnace body 21 on the side of the door 11, and when the door 13 is opened, the heating chamber is opened. 32 and the heat exchanger 41 communicate with each other.

On the other hand, between the heating chamber 32 surrounded by the heat insulating material 31 and the furnace main body 21, a total of 12 pipes 61 whose tips on the side of the door 11 are closed are formed at predetermined intervals in a ring shape as a whole in the furnace length direction. The pipes 61 are arranged side by side (the number of pipes 61 is increased or decreased as necessary), and the base ends of these pipes 61 communicate with the fan 51. Five nozzles 71 are attached at predetermined intervals to each of the twelve pipes 61 (the number of nozzles 71 is increased or decreased as necessary).
It penetrates through 31 and is inserted into heating chamber 32. Attachments 81 are attached to the tips of the nozzles 71, respectively.

FIG. 3 is a partially enlarged sectional view showing the relationship between the nozzle and the attachment in the same embodiment as FIGS. 1 and 2. An attachment 81 made of a cylindrical part as a whole is slidably in contact with the outer periphery of the tip of the nozzle 71 with a screw 91, and the tip of the attachment 81 is inclined. 91 at nozzle 71
It can be changed depending on the stop position.

After heating the material to be heated A in a predetermined manner in the heating chamber 32,
The heating source is turned off, the doors 12 and 13 are opened, a cooling gas is introduced into the furnace body 21 and the heating chamber 32 from outside the furnace, and the heat exchanger 41 and the fan 51 are operated. The cooling gas is supplied to the heat exchanger 41 →
The circulation is performed in the order of the fan 51 → pipe 61 → nozzle 71 → attachment 81 → heating chamber 32 / heated material A → openings 33 and 34 → heat exchanger 41 to gas-cool the heated material A In this case, according to the shape of the material A to be heated, for example, if the material A to be heated is a thin object such as a drill, the attachment 81 is blown out in advance in such a manner that the cooling gas is parallel to the drill. , And point it.

When performing a quenching test on a round bar (SKH51) with an outer diameter of 10 mm and a length of 150 mm, if a cooling gas is blown out perpendicular to the round bar without attaching an attachment like a conventional furnace, Although the distortion of the round bar was 0.2 mm, when the attachment 81 was attached as in the illustrated embodiment and the cooling gas was ejected in parallel with the round bar, the distortion of the round bar after cooling was reduced. The hardness was improved to less than 0.05 mm (both were average values of 10 round bars, and there was no difference in hardness of the round bars after cooling).

<Effects of the Invention> As described above, the present invention has an effect that distortion generated in a material to be heated after vacuum heat treatment can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part in a furnace length direction showing one embodiment of the present invention, FIG. 2 is an enlarged sectional view of an essential part in a furnace width direction showing the same embodiment as FIG. 1, and FIG. FIG. 3 is a partially enlarged cross-sectional view showing a relationship between a nozzle and an attachment in the same embodiment as FIGS. 1 and 2. 11, 12, 13 ... Door, 21 ... Furnace body 31 ... Insulation material, 32 ... Heating chamber, 41 ... Heat exchanger 51 ... Fan, 61 ... Pipe, 71 ... Nozzle 81 ... Attachment , A ... Heated material

Claims (1)

(57) [Claims] 1. A heating chamber surrounded by a heat insulating material is formed in a furnace body, and after a material to be heated is vacuum-heated in the heating chamber,
In a vacuum heat treatment furnace in which gas is cooled by circulating a cooling gas cooled by a heat exchanger, a plurality of pipes for introducing a cooling gas into a heating chamber are provided between the furnace body and a heat insulating material forming a heating chamber. A plurality of nozzles are installed in parallel with each other and inserted into the heating chamber through the heat insulating material in each of the pipes, and control the jetting direction of the cooling gas at the tip of each of the nozzles. The vacuum heat treatment furnace is configured such that an attachment to be attached is attached and the direction of jetting of the cooling gas can be changed by the attachment.