JPH0523496U - Induction plasma torch for decompression - Google Patents

Abstract

(57) [Abstract] [Purpose] Prevents the contact of the plasma flame generated in the induction plasma torch with the upper part of the decompression chamber, and performs good thermal spraying. [Structure] An outer tube 2 and inner tubes 3 and 4, which are attached to a lower end attachment portion 11 of the outer tube 2 and are attached to an upper portion 12 of a decompression chamber at a lower portion of the lower end attachment portion 11 of the outer tube 2 of the induction plasma torch. By providing the cylindrical insulating barrier 15 connected to the mounting portion 11 and extending inside the chamber, contact of the generated plasma flame 7 with the chamber upper portion 12 was prevented.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a decompression induction plasma torch that can generate a plasma flame stably without contacting the upper part of a grounded decompression chamber.

[0002]

[Prior Art]

 Conventionally, as a plasma torch 1 for generating an induction plasma, as shown in FIG. 2, for example, quartz glass, boron nitride or other refractory is used, and an outer tube 2 and a first inner tube 3 and In some cases, an inner tube 4 is provided, and an outer tube 2 is provided with a plasma gas introduction tube 5 and a sheath gas introduction tube 6 at one end in parallel with the central axis.

A tip of a plasma gas introduction pipe 5 that guides plasma gas for generating plasma into the first inner pipe 3 is connected via a joint 8.

In addition, in the space between the first inner pipe 3 and the outer pipe 2, the tip of the sheath gas introduction pipe 6 for introducing the plasma gas and the sheath gas for sealing the plasma frame 7 is connected via the joint 9. Connected.

In connecting the plasma gas introducing pipe 5 and the sheath gas introducing pipe 6 through joints, the central axis line is set so that the plasma gas or the sheath gas spirally moves in a predetermined pipe. It is necessary to make a connection at right angles to or in the direction of inclination.

[0006] Reference numeral 10 is a load introduction portion for powder when performing plasma spraying, but it may not be necessary when heating is performed using a plasma frame. Reference numeral 11 is an attachment portion for attaching the plasma torch 1 to the upper portion 12 of the decompression chamber, and 13 is a water cooling pipe for cooling the outer tube and the chamber.

In such a plasma torch, the outer tube 2, the first inner tube 3 and the second inner tube 4 are made of quartz glass, boron nitride or other refractory material having good roundness. Also, when connecting the plasma gas introducing pipe and the sheath gas introducing pipe to a predetermined pipe through a joint, the plasma gas introducing pipe and the sheath gas introducing pipe are sealed with silicon nitride or the like.

The joints 8 and 9 in the connection of the plasma gas introduction pipe and the sheath gas introduction pipe are formed with grooves or hollows in a direction in which the gas can spirally rotate, but not the joint, but the upper part of the outer pipe is sealed and both introductions are performed. Sometimes the tube is guided directly through the outer tube. Reference numeral 14 is a high-frequency coil which is inserted into the outer portion of the outer tube 2 from the introduction tube side and set at a predetermined position. A high frequency is applied to the high frequency coil 14, and the plasma gas serves as a plasma flame for heating a load (powder) and spraying.

[0009]

[Problems to be solved by the device]

 However, in the induction plasma torch as described above, the generated plasma flame 7 comes into contact with a part of the upper portion 12 of the decompression chamber which is connected to the lower end mounting portion 11 of the outer tube 2 and is grounded as shown in FIG. Therefore, there is a problem that not only the molten powder is not sprayed favorably onto the object to be sprayed (not shown), but also the plasma torch itself is damaged.

[0010]

[Means for Solving the Problems]

 As a result of studies to solve the above-mentioned problems in the conventional induction plasma torch, the present invention, as a result of the examination, has a cylindrical barrier under the mounting portion at the lower end of the outer tube inside the pressure reducing chamber so as to cover the generated plasma flame. It was found that the

That is, the present invention is composed of an outer tube and an inner tube, and is attached to the upper part of the decompression chamber at the lower end attachment part of the outer tube, and plasma gas is introduced into the inner tube between the outer tube and the inner tube. In a decompression plasma torch having a structure for introducing sheath gas, a decompression induction plasma torch provided with a cylindrical insulating barrier connected to the lower end of the outer tube and connected to the attachment part and extending into the chamber. It is provided.

[0012]

[Action]

 According to this invention, a cylindrical insulating barrier is provided inside the chamber so as to be connected to the mounting portion at the lower end of the outer tube of the induction plasma torch, thereby preventing the generated plasma flame from contacting the upper part of the chamber.

[0013]

【Example】

 The present invention will be described below with reference to FIG. 1 showing an embodiment thereof. It should be noted that reference numerals 1 to 14 in FIG. 1 indicate the same parts as the reference numerals 1 to 14 in FIG. 2 showing a conventional plasma torch, and their functions are also the same, and therefore their explanations are omitted.

In FIG. 1, reference numeral 15 is an insulating barrier provided so as to be connected to the lower end mounting portion 11 of the outer tube 2. The barrier 15 has a cylindrical shape and is located inside the upper portion 12 of the decompression chamber, and a length of 1.1 to 1.5 times the thickness of the chamber upper portion 12 is suitable. Further, it is preferable that the barrier 15 is provided integrally with the lower end mounting portion 11 of the outer tube 2 as illustrated.

To describe a specific example using the plasma torch of the present invention, the inner diameter r of the outer tube 2₁= 24 mm, the diameter r of the opening of the decompression chamber 12₂= 50 mm, thickness t of upper chamber 12 = 20 mm, length h of barrier wall = 25 mm, diameter r of mounting portion 11 of outer tube 2 ₃ = 70 mm plasma torch, using argon gas as plasma gas and sheath gas, and applying a power of 3 KW and a frequency of 13.56 MHz to the high frequency coil 14 under vacuum of 250 Torr or less, plasma spraying of metal powder was performed. It was not observed that the generated plasma flame crossed the barrier 15 and came into contact with the upper chamber 12, and the installation of the barrier allowed good spraying with a normal plasma flame.

[0016]

[Effect of the device]

 As described above, the present invention provides a cylindrical barrier longer than the upper thickness of the decompression chamber so as to extend into the decompression chamber by connecting to the lower end of the outer tube of the induction plasma torch. It prevents the plasma flame generated when the torch is used from contacting the upper part of the chamber. This has been confirmed to have the effect of achieving good thermal spraying and preventing damage to the torch.

[Brief description of drawings]

1 is a cross-sectional view of a decompression induction plasma torch of the present invention.

FIG. 2 is a sectional view of a conventional decompression induction plasma torch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma torch 2 Outer tube 3 1st inner tube 4 2nd inner tube 7 Plasma flame 11 Outer tube lower end mounting part 12 Chamber upper part 14 High frequency coil 15 Insulating cylindrical barrier

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Jun Okada 2-14-3 Awaji, Higashiyodogawa-ku, Osaka City, Osaka Prefecture Sansha Electric Manufacturing Co., Ltd. (72) Yuya Murata 2-chome, Awaji, Higashiyodogawa-ku, Osaka City, Osaka Prefecture Sanwa Denki Seisakusho Co., Ltd. (72) Inventor Hidehisa Tachibana 2-14-3 Awaji, Higashiyodogawa-ku, Osaka-shi, Osaka

Claims (1)

[Scope of utility model registration request] 1. An outer tube and an inner tube, which are attached to an upper portion of a decompression chamber at a lower end attachment portion of the outer tube, and introduce a plasma gas into the inner tube and a sheath gas between the outer tube and the inner tube, respectively. In the decompression plasma torch having the structure described above, a decompression induction plasma torch is provided below the lower end mounting portion of the outer tube, and provided with a cylindrical insulating barrier that is connected to the mounting portion and extends into the chamber.