JPS5919723Y2 - Ion nitriding equipment - Google Patents

Description

[Detailed explanation of the invention] This invention ionizes nitrogen gas by glow discharge,
The present invention relates to an improvement of an ion nitriding apparatus that performs nitriding by colliding the nitrogen ions with a workpiece.

Conventionally, this type of equipment uses a cathode,
Direct current voltage is applied in vacuum (1 to 10 Torr) using the furnace wall as an anode to generate a glow discharge.The glow discharge ionizes nitrogen gas, and while the nitrogen ions collide with the workpiece, The nitriding treatment was performed by heating the object and then maintaining the object at the treatment temperature by glow discharge.

Therefore, if the object to be treated is initially cold, glow discharge becomes unstable, and depending on the degree of vacuum, gas atmosphere, etc., local arc discharge may occur, making it impossible to process uniformly, and heating takes time. The drawback was that the cycle efficiency was poor.

Furthermore, even after the processing temperature (300 to 570'C) has been reached, glow discharge concentrates on parts that have sharp points or pores due to the shape of the object, causing local overheating. It also had the disadvantage that uniform nitriding treatment could not be performed.

Furthermore, as the amount of material to be treated increases, it is necessary to increase the glow discharge output required for nitriding, but on the other hand, if the amount of heat released outside the furnace during nitriding is small, this may lead to overheating of the entire material to be treated. In some cases, nitriding becomes impossible.

Therefore, in order to perform the ion nitriding process uniformly and efficiently, a heating element is placed around the outer periphery of the vacuum reactor, and the workpiece is heated and nitrided using a combination of glow discharge and heat generated by the heating element. An ion nitriding apparatus as described above was developed by the inventors of the present invention.

The present invention is a further improvement of the ion nitriding apparatus that uses heat generated by a heating element in addition to the glow discharge described above, and enables heating of the object to be treated and nitriding treatment to be performed more thermally efficiently, in a shorter time, and more uniformly. An inner wall shield that can be opened and closed is installed on the inner periphery of the heating element, and a blind shutter means that can be opened and closed is installed on the outer periphery of the heating element, and the heating rate is adjusted by closing the blind shutter means at the same time as opening the internal heat shielding at the time of preheating. On the other hand, during nitriding, by closing the inner wall shield and opening the blind shutter means according to the amount of heat released, the amount of heat released outside the furnace due to glow discharge is adjusted, preventing overheating of the workpiece, and improving nitriding efficiency. An object of the present invention is to provide an ion nitriding treatment apparatus that improves the performance of the ion nitriding process.

The present invention will be described below based on embodiments shown in the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a steel vacuum reactor, which includes a cylindrical furnace body 2 and a lid body that covers the upper opening (portion for carrying in and out of the processed material) of the furnace body 2. 3, and the furnace body 2 and lid body 3 each have a water-cooled double structure so as to be cooled to an appropriate temperature.

Heat generating elements 4 arranged in a cylindrical shape are arranged concentrically with the furnace body 2 on the outer periphery of the vacuum reactor 1 .

On the inner circumferential side of the heating element 4, an openable and closable inner wall shield 7 is arranged, which is made up of a cylindrical arrangement of a large number of band-like rotating plates 6 rotatably attached to a vertical shaft 5. , each rotating plate 6 during the closing operation.
The heating elements 4 are oriented in the tangential direction and are continuous on the circumference.
In order to electrically shield the inner circumferential side of the heating element 4 from the object to be treated 8 (cathode) (see the lower half of Fig. 2), each rotary plate 6 is oriented radially in the direction of the heating element 4 during the opening operation. The inner circumferential side is open (see the upper half of FIG. 2).

Further, on the outer circumferential side of the heating element 4, an openable/closeable blind shutter means 11 is arranged, which is formed by arranging a large number of strip-shaped blinds 10 rotatably mounted on a vertical shaft 9 on the circumference. During the closing operation, each blind 10 faces in the tangential direction and is continuous on the circumference to shield the outer peripheral side of the heating element 4 (
As shown in the upper half of FIG. 2), each blind 10 is configured to face in the radial direction and open the outer circumferential side of the heating element 4 during the opening operation (see the lower half of FIG. 2). .

12 is a glow discharge power source that applies a DC voltage between the two electrodes, with the inner wall shield 7 as an anode and the workpiece 8 charged in the vacuum reactor 1 as a cathode; 13, a glow discharge power source that applies an AC voltage to the heating element 4; A power supply for a heating element to which the power is applied, the heat generation substitute power supply 13
A temperature control device 15 having a temperature measuring thermocouple 14 inserted into the vacuum reactor 1 is connected to the vacuum reactor 1, and is configured to detect the temperature inside the furnace and control the power source 13 for the heating element. .

Reference numeral 16 denotes a cathode mounting table on which the object to be processed 8 is placed, and is supported at the bottom of the vacuum reactor 1 by a tripod-shaped support 17 made of an insulating material.
A conductive disk 18 having a convex lower surface and an insulating disk 19 having a flat upper surface are stacked and fitted to the corresponding core portion so that the glow discharge does not concentrate on the portion that abuts the upper surface. A wedge-shaped slit is formed between 18 and disk 19.

20 is a cathode terminal 2 placed on a cathode mounting table 16 from outside the vacuum reactor 1.
A terminal introduction tube 22 is a support leg of the vacuum reactor 1 and has electrical insulation and vacuum sealing properties for introducing the reactor 1 .

Next, to explain its operation, when a direct current voltage is applied between the inner wall shielding body 7 as an anode and the cathode mounting table 16 (i.e. the object to be treated 8) as a cathode using the glow discharge power supply 12, a glow discharge occurs. On the other hand, when an AC voltage is applied to the heating element 4 by the heating element power supply 13, heat is generated.

The processing temperature (300 to 570°C, preferably 550 to 560°C) at which the workpiece 8 charged in the vacuum reactor 1 can be discharge nitrided
), the heating is performed only by the heat generated by the heating element 4, and the inner wall shield 7 is opened and the blind shutter means 11 is closed, as shown in the upper half of FIG.

Therefore, by opening the inner wall shield 7, the heat generated by the heating element 4 directly radiates and heats the object 8, and at the same time,
By keeping the blind shutter means 11 closed,
Since the heat rays trying to be emitted from the outer periphery of the heating element 4 to the outside of the furnace can be blocked and the amount of emitted heat can be reduced, the heat treatment of the workpiece 8 can be efficiently performed in a short time and uniformly.

Subsequently, after preheating to the processing temperature, the second
As shown in the lower half of the figure, the inner wall shield 7 is closed to electrically shield the heating element 4 from the object to be processed 8, and while the object to be processed 8 is maintained at the processing temperature by the heat generated by the heating element 4, The nitriding treatment is performed in combination with glow discharge using the inner wall shielding body 7 as an anode.

During this nitriding treatment, the glow discharge output is increased in accordance with the amount of charged material 8, while the heat generation by the heating element 4 is stopped or controlled, and the blind shutter means 11 is adjusted according to the amount of heat radiation. By adjusting the opening and closing, the amount of heat released outside the furnace is increased in accordance with the increase in the glow discharge output required for nitriding, preventing overheating of the object 8 to be treated, increasing the nitriding efficiency, and performing the nitriding process uniformly. Can be done.

Furthermore, since the heating element 4 is electrically shielded from the workpiece 8 (cathode) by the closed inner wall shield 7, arc discharge or abnormal glow may occur between the heating element 4 and the workpiece 8. No discharge occurs.

In this way, when the glow discharge output necessary for nitriding is large at the nitriding temperature and the temperature of the workpiece 8 tends to rise even by glow discharge alone, such as when a large amount of the workpiece 8 is charged, the blind shutter means 11 is opened to an opening degree corresponding to the degree of rise, the heat generation by the heating element 4 is stopped or controlled, and the heat radiation to the outside of the furnace is increased to prevent overheating of the workpiece 8 and to reduce the glow discharge output necessary for nitriding. is small and good;
When the temperature of the object 8 tends to decrease with glow discharge alone, it is also possible to close the blind shutter means 11 and perform heating by the heating element 4 at the same time.

Thereby, it is extremely easy to accurately and uniformly maintain the target temperature of the workpiece 8, regardless of the level of the nitriding temperature, the magnitude of the discharge output, or the amount of the workpiece 8 charged.

In addition to the above-mentioned opening/closing structure for the inner wall shield 7 and the blind shutter means 11, as shown in FIG. a concentric cylindrical body 23 having
．． 24 is interposed on the inner or outer periphery of the heating element 4, and one of the cylindrical bodies 23 and 24 is rotated to open the rectangular holes 23a and 24.
An opening/closing structure may be used in which the opening/closing structure is configured to open when the openings a match and close when they do not match.

In addition to the above-mentioned strip-shaped holes 23a and 24a, the holes may have various shapes such as square holes and rectangular holes.

Further, the heating element 4 may have a multi-segmented structure in which it is vertically divided into two or more parts, and the output of each divided heating element may be individually controlled.

In this case, there is an advantage that the temperature distribution in the furnace can be made good and uniform.

Therefore, according to the present invention, the workpiece can be heated by the heat generated by the heating element, and the workpiece can be nitrided by a combination of glow discharge and heat generation by the heating element. It is possible to prevent the occurrence of local arc discharge due to local overheating of the object to be treated, and to perform heating and nitriding of the object to be treated uniformly in a short time, thereby improving one-cycle thermal efficiency and processing efficiency. At the same time, when preheating the object to be processed, the inner wall shield is opened to improve the heating efficiency of the object to be processed by the heating element, and at the same time, by closing the blind shutter means, the amount of heat released outside the furnace is reduced, and the heating efficiency is improved. It can be further improved.

Furthermore, when nitriding the workpiece, the inner wall shield is closed to prevent the occurrence of arc discharge and the like to obtain a stable glow discharge, while the amount of heat released outside the furnace is controlled by opening and closing the blind shutter means to prevent overheating. The nitriding efficiency can be further improved and the nitriding process can be performed satisfactorily and uniformly.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view showing the overall structure, FIG. 2 is a cross-sectional view showing the upper half in a preheated state and the lower half in a nitrided state. The figure is a partially cutaway front view of a main part showing a modification of the inner wall shield or blind shutter means. 1... Vacuum reactor, 2... Furnace body, 3.
... Lid body, 4 ... Heating element, 5 ...
・Vertical axis, 6... Rotating plate, 7... Inner wall shield, 8... Processing object, 9... Vertical axis, 10... ... Blind, 11 ... Blind shutter means, 12 ... Power supply for glow discharge, 13 ... Power supply for heating element, 14 ...
・Thermocouple for temperature measurement, 15...Temperature control device, 16
・・・・・・Cathode mounting table, 16 a・・・・Legs,
17...Support stand, 18...Disc, 19
...Disk, 20...Terminal introduction tube, 21
...Cathode terminal, 22... Support leg, 23.
24... Cylindrical body, 23a, 24a...
Rectangular hole.

Claims (1)

[Scope of utility model registration request] In an ion nitriding treatment apparatus in which a heating element is disposed on the outer periphery of a vacuum reactor and a workpiece is nitrided by a combination of glow discharge and heat generated by the heating element, the inner periphery of the heating element can be opened and closed. In addition to shielding with an inner wall shielding member, a blind shutter means that can be opened and closed is provided on the outer periphery of the heating element, and the inner wall shielding member opens during preheating of the object to be treated and closes during nitriding to constitute an anode for glow discharge. An ion nitriding treatment apparatus characterized in that the apparatus is closed when preheating the object to be treated and is controlled to open and close during nitriding according to the amount of heat released.