JPS5914103B2 - Ion nitriding equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to an ion nitriding apparatus.

Specifically, the present invention creates an atmosphere of a processing gas consisting of or containing nitrogen in an airtight tank containing a workpiece, and applies a voltage between an anode and a cathode in the airtight tank. The present invention relates to an ion nitriding treatment apparatus that generates a glow discharge, ionizes nitrogen in a processing gas by the action of the glow discharge and voltage, and causes the formed nitrogen ions to collide with the workpiece to nitridize the workpiece. In conventional ion nitriding equipment, the airtight tank is used as an anode, or an auxiliary electrode is provided as part of the anode, and a support such as a support stand or a hanging jig is held at an anode potential. Electrodes are arranged in such a way that the object to be treated is used as a cathode, and a voltage is applied between the cathode and the anode to generate glow discharge.

5 However, when the hermetic tank is used as an anode in this way, discharge accompanied by electron bombardment occurs in unnecessary parts of the hermetic tank, and the discharge tends to shift to arc discharge, causing damage to the constituent parts of the hermetic tank. Contaminants accumulated in the corners cause arcing, and together with these points10 a very large one-hour arc occurs during the early stages of operation, both of which obviously interfere with the production and maintenance of the desired glow discharge. .

Furthermore, although it was not mentioned above, the airtight tank is cooled to prevent overheating and the single-strength nitriding process is carried out at about 540°C, so the cathode to be treated is placed directly in front of the anode airtight tank in order to generate electric discharge. The conventional deployment described above results in large heat losses. In addition, with such a conventional arrangement, there is a risk that the objects to be treated may be contaminated due to dirt in the airtight tank. Furthermore, it is desirable that the anode can be cleaned by decomposition, but cleaning cannot be easily achieved when an airtight tank is used as the anode. The main purpose of this generation is to eliminate the drawbacks of conventional ion nitriding processing equipment, mainly due to the electrode arrangement as described above.

In order to achieve this object, the present invention is characterized in that the object to be treated is used as a cathode, and an anode that at least partially covers the cathode is disposed in an airtight tank to make the airtight tank electrically neutral. shall be. According to this feature, the airtight tank is a neutral 3
0 and because this hermetic chamber is virtually isolated from the discharge space between the workpiece and the anode surrounding it at least partially, all of the conventional drawbacks associated with arc discharge are eliminated. removed to facilitate the initiation, generation and maintenance of a glow discharge.

Further, since the anode 35 constitutes a kind of heat insulating plate, that is, a heat reflecting plate, disposed between the airtight tank and the object to be treated, heat loss is significantly reduced compared to the conventional one. This reduction in heat loss was approximately 40% in one example. Moreover, since the anode can be arranged in a removable manner, cleaning is thereby considerably simplified. In addition to these points, the anode in this arrangement is located in such a position as to prevent contamination of the treated material due to contamination of the airtight tank. Embodiments of the ion nitriding apparatus of the present invention will be described below with reference to the drawings. In the illustrated embodiment of the ion nitriding treatment apparatus, the airtight tank 10 is composed of a horizontal substrate 11 and a bell-shaped tank body 12 that is removably and airtightly connected to the upper peripheral edge of the horizontal substrate 11, as shown at 32. grounded.

A support stand 15 that supports a workpiece 14 in an airtight tank is connected to a substrate 1 by its legs through an electrical insulator 16 in airtight engagement.
Attached to 1. The treatment gas inlet member 17 is substantially tubular in shape, has an inlet opening 18 at its lower end, and passes through the top opening 19 of the tank body 12 in its upper part. Feeding member 17
The flange 20 attached to the upper part of the top opening 19
It is connected to the tank body 12 via an electrical insulator 21 that covers the body and is in airtight engagement. The upper opening of the feed member 17 is connected to a feed pipe 22 having an electrically insulating part and a valve 23 disposed therein.
It is connected to the processing gas source 24 via. The substrate 11 has a discharge opening 25, which is connected to a vacuum evacuation device 28 via a discharge pipe 26 and a valve 27 arranged therein. The anode 29 is a bell-shaped metal plate placed in the airtight tank 10 so as to cover the top and sides of the workpiece 14, and is mechanically attached to the feeding member 17 and attached thereto. electrically connected.

The feed member 17 is connected to a power source 31 via a switch 30 in order to bring the anode 29 to a positive potential. The support base 15 is connected to a power source 31 via a switch 30 in order to set the support base 15 at a negative potential with respect to the anode potential and make the object to be treated 14 a cathode. In the ion nitriding apparatus configured as described above,
By activating the vacuum evacuation device 28 and opening the valve 27 to evacuate the inside of the airtight tank to a high degree of vacuum, and then opening the valve 23, the processing gas is passed from the gas source 24 through the piping 22 and further through the inlet member 17. The airtight tank 10 is filled.

The pressure of the processing gas in the airtight tank is maintained at a value (low pressure) suitable for glow discharge by adjusting the valves 23 and 27. Next, when the switch 30 is closed and a voltage suitable for generating a glow discharge is applied between the anode 29 and the cathode 14, the nitriding treatment of the object 14 is accomplished as described above. According to such an ion nitriding treatment apparatus, the anode 29 is positioned so as to cover the upper side and the side of the object to be treated 14, which can be used as a cathode, and to isolate between the object to be treated 14 and the airtight tank 10. In addition, since the airtight tank 10 is maintained air-neutral, there is no interference with the generation and maintenance of glow discharge due to arc discharge, and furthermore, the anode 29 constitutes a heat insulating plate, that is, a heat reflecting plate, and prevents the generation and maintenance of glow discharge due to arc discharge. It helps reduce losses and also achieves a contamination blocking effect.

Further, although not specified in the above description, the anode 29 can be removably attached to the feeding member 17, and if the tank is constructed in this way, the anode can be cleaned up very easily.

[Brief explanation of drawings]

The drawing is an illustrative view showing one embodiment of the ion nitriding apparatus according to the present invention. In the drawing, 10 is an airtight tank, 14 is an object to be processed, 18 is a processing gas inlet member, 25 is a processing gas discharge opening, 2
9 is an anode, and 31 is a power source for voltage application.

Claims (1)

[Claims] 1 Create an atmosphere of a processing gas consisting of or containing nitrogen in the airtight tank containing the object to be treated, and generate a glow discharge by applying a voltage between the anode and the cathode in the airtight tank, In an ion nitriding treatment apparatus that ionizes nitrogen in a processing gas by the action of glow discharge and voltage and causes the formed nitrogen ions to collide with the workpiece to nitride the workpiece, the workpiece is used as a cathode, An ion nitriding treatment apparatus characterized in that an anode that at least partially covers the anode is disposed in an airtight tank to make the airtight tank electrically neutral.