JPH01147052A - Method and apparatus for operating ionic carburization furnace - Google Patents

Abstract

PURPOSE:To uniformize the concn. of treatment gas around a material to be treated and to reduce scattering of carburization depth of the material to be treated by introducing the treatment gas into a furnace while moving a gas manifold in the furnace. CONSTITUTION:The inside of an ionic carburization furnace 30 is heated at proper temp. with a heater 7 and decompressed and gas is introduced into the furnace 30 from the feed source 19 of treatment gas while continuously rotating a gas manifold 20 around a vertical axial line 13 at low velocity to the unidirection and moving it with a main axis driver 14. DC high voltage is impressed between a material 5 to be treated and an anode 2 and ionic carburization treatment of the surface of the material 5 to be treated is performed by carbon ionized with generated plasma. Since the treatment gas is introduced into the furnace 30 through a gas blowing port 24 of the moving gas manifold 20, the concn. of the gas around the material 5 is uniformized and scattering of carburization depth of the surface of the material 5 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of operating an ion carburizing furnace and an apparatus therefor.

(Prior art) Recently, as a method for hardening the surface of objects to be treated such as steel, a processing gas consisting of a CH-based gas is introduced into a vacuum container containing the objects to be treated, and a glow discharge is caused between the object to be treated and the anode. generate,
Ion carburizing (also called plasma carburizing), in which ionized carbon is implanted into the surface of a workpiece, has been put into practical use. Figure 5 shows an example of the loading for this treatment method, where 1 is a steel furnace shell, 2 is a graphite anode that also serves as a heat insulator, and 3 is a stainless steel cathode, the base of which is an insulator. It is fixed to the furnace shell 1 via 4. 5 is a workpiece attached to a mounting jig, 6 is a graphite hearth on which the workpiece 5 is placed,
It is fitted into the upper end of the shade VM3. Reference numeral 7 denotes a round rod-shaped heater made of graphite that generates heat through resistance heating and heats and raises the temperature of the object to be processed 5 mainly by radiant heat, and 8 is a tubular gas manifold made of graphite for supplying processing gas. . Further, 9 is a vacuum pump connected to the furnace shell 1.

[Problem that the invention seeks to solve]

By the way, since ion carburizing is generally performed at a low pressure of about 1 to 1 QTOrr, the gas diffusion ability within the furnace is low.In contrast, in the ion carburizing furnace 10 having the above configuration, the gas manifold 8 is located at a fixed position within the furnace. Therefore, it is difficult to uniformly diffuse the processing gas, and there is a problem that the carburization depth of the object to be processed varies widely.

This invention solves the above-mentioned conventional problems, and is an ion carburizing method that can equalize the processing gas concentration around the workpiece in the furnace and reduce variations in carburization depth of the workpiece. and its equipment.

[Means for solving problems]

However, in the method of the present invention, an ion carburizing furnace is provided with an anode, a cathode, and a heater for heating the workpiece in a furnace shell connected to a vacuum pump, which is connected to a processing gas supply source and opened into the furnace. A gas manifold with a gas outlet,
This is a method of operating an ion carburizing furnace, characterized in that the process gas is introduced into the furnace while being moved within the furnace shell.

Further, the apparatus of the present invention is used in an ion carburizing furnace in which an anode, a cathode, and a heater for heating a workpiece are provided in a furnace shell connected to a vacuum pump. A gas manifold having a gas outlet opening into the furnace is connected to a hollow main shaft rotatably supported by the furnace shell, and the main shaft is connected to a processing gas supply source via a rotary joint. , an ion carburizing furnace characterized by comprising a main shaft drive device that engages with the main shaft and rotationally drives the main shaft.・[Function] In this invention, during ion carburizing, the processing gas is introduced into the furnace from the gas outlet of the moving gas manifold, and the processing gas concentration around the workpiece is made uniform, thereby making the glow The carbon ion concentration during discharge is also made uniform, and variations in the carburization depth of the object to be treated are reduced.

Further, in the apparatus of the present invention, the gas manifold can be continuously rotated in one direction or oscillated through a predetermined angle around the vertical axis by the main shaft drive device. The processing gas blown out from this rotating gas manifold is uniformly sprayed around the object to be processed, thereby making the processing gas concentration uniform. Further, the processing gas from the processing gas supply source can be supplied to the gas manifold, which rotates reliably and easily, via the rotary joint.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

In the figure, the same parts as in FIG. 5 are designated by the same reference numerals as in FIG. 5, and the explanation thereof will be omitted. Reference numeral 11 denotes a cylindrical main shaft made of carbon, which passes through the furnace shell 1 and is supported by a bearing 12 attached to the furnace shell 1 so as to be rotatable around a vertical axis 13 passing through the center of the hearth 6.

14 is a main shaft drive device, which is a motor 15 installed on the furnace shell 1.
A drive gear 16 is fixed to the output shaft of the main shaft 11, and this drive gear 16 meshes with a driven gear 17 fixed to the main shaft 11. Further, 18 is a rotary joint into which the upper end of the main @ 11 is fitted, and the main @ 11 is connected to a processing gas supply source 19 via this rotary joint 18 . On the other hand 2
0 is a carbon gas manifold connected to the lower end of the main shaft 11, which includes a main pipe 21 whose intermediate part is connected to the main shaft 11 and extends in the horizontal direction, and a curved branch pipe 22 connected to both ends of this main pipe 21. and a plurality of branch pipes 23 whose upper ends are connected to this branch pipe 22 and whose lower ends are sealed.

The main shaft 11 , the main pipe 21 , the branch pipe 22 , and the branch pipe 23 have internal hollow parts that are continuous with each other, and the pipe wall of the branch pipe 23 has a plurality of gas outlet openings that open toward the object to be processed 5 . 2
Furthermore, as shown in FIG. 1, a DC power source 25 for glow discharge is connected between the cathode 3 and the anode 2, and an AC power source 26 for heating is connected to the heater 7. 27 is a gate valve type charging port door, and 28 is an air cylinder for driving the cargo unloading of this door.

In the ion carburizing furnace 30 having the above configuration, the heater stores hot water in the furnace up to the carburizing temperature, the vacuum pump 9 is operated to reduce the pressure in the furnace, and the main shaft drive device 14 is operated to move the gas manifold 20 along the vertical axis. The processing gas is introduced into the furnace from the processing gas supply source 19 while continuously rotating in one direction at low speed around the processing gas supply source 19 . And the furnace pressure is 0.5~1Q
While maintaining the pressure at Torr, a DC high voltage is applied between the workpiece 5 and the anode 2 by the DC power supply 25, plasma is generated by DC glow discharge, and the carbon ionized by this plasma causes the surface of the workpiece to be heated. Perform ion carburizing treatment. Since the processing gas is introduced into the furnace from the gas outlet 24 of the rotating gas manifold 20, the processing gas
The processing gas concentration around the object 5 is made uniform, and the variation in carburization depth on the surface of the object 5 is reduced.

Ion carburizing furnace 30 with the above configuration (inner diameter of furnace shell 1 -1
200M), the gas manifold 20 was rotated at a speed of 3 times per minute to process the workpiece 5, which was loaded with 80M420 automobile gears stacked in 5 stages with 23 gears per stage on a mounting jig. Propane gas 15fJ/
Using a mixed gas of min and nitrogen gas 5ρ/n+in,
Carburizing at 870°C for 40 minutes at a furnace pressure of 2.5 Torr,
This was followed by a 2 hour diffusion process. Further, as a comparative example, the gas manifold 20 was stopped, and the ion carburizing treatment was performed under the same conditions as above. As a result, the variation in carburization depth of the workpiece 5 was ±0.085 m in the example of the present invention, while it was ±0.2 m in the comparative example.
A variation of more than twice that of 5 m was actually measured.

The present invention is not limited to the above embodiments; for example, instead of continuously rotating in one direction, the gas manifold 20 may be reciprocated within a certain angle range, such as 90 degrees or 180 degrees. . Further, instead of rotating the gas manifold as described above, the gas manifold 20 may be moved back and forth in a linear direction as shown in FIG. Note that 31 in the figure is a gas manifold fixed in the furnace, and the same parts as in FIG. 3 are given the same symbols as in FIG. 3. Further, it is also possible to use a gas manifold having a structure other than that described in F, such as having the branch pipes 23 arranged horizontally.

[Effects of the Invention] As explained above, according to the present invention, the processing gas is introduced into the furnace while the gas manifold is moved within the furnace, so that the processing gas concentration around the object to be processed is uniform. This makes it possible to reduce variations in the carburizing depth of the workpiece.

[Brief Description of the Drawings] Fig. 1 is a longitudinal sectional view of an ion carburizing furnace showing an embodiment of the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, and Fig. 3 is the same <B- A sectional view taken along line B, FIG. 4 is a view corresponding to FIG. 3 showing another embodiment of the present invention, and FIG. 5 is a view corresponding to FIG. 2 showing an example of a conventional ion carburizing furnace. 1... Furnace shell, 2... Anode, 3... Cathode, 7...
Heater, 9... Vacuum pump, 11... Main shaft, 12.
... bearing, 13 ... vertical axis, 14 ... main shaft drive device, 18 ... rotary joint, 19 ... processing gas supply source, 20 ... gas manifold, 24 ...
Gas outlet, 30...Ion carburizing furnace. 4th eye

Claims (1)

[Scope of Claims] 1. In an ion carburizing furnace that is equipped with an anode, a cathode, and a heater for heating a workpiece in a furnace shell connected to a vacuum pump, a gas connected to a processing gas supply source and opened into the furnace 1. A method for operating an ion carburizing furnace, comprising introducing a process gas into the furnace while moving a gas manifold having an outlet within the furnace shell. 2. In an ion carburizing furnace that is equipped with an anode, a cathode, and a heater for heating a workpiece in a furnace shell connected to a vacuum pump, the furnace can be freely rotated around a vertical axis through the furnace shell. A gas manifold having a gas outlet opening into the furnace is connected to a hollow main shaft supported by the shell, and the main shaft is connected to a processing gas supply source via a rotary joint, and the main shaft is engaged with the main shaft. An ion carburizing furnace characterized by comprising a main shaft drive device that rotationally drives the main shaft.