JPH11104824A - Controlling device for injecting inert gas to metallic tube at the time of welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and surely inject inert gas at the time of welding a metallic tube and to prevent the oxidation of the inner surface of the metallic tube by fitting a gas injecting nozzle to a cylinder of inert gas through a pressure reducing valve and a solenoid valve and injecting the inert gas into the metallic tube. SOLUTION: The one end part of one metallic tube to be connected, is inserted into the corresponding end part of the other metallic tube and the other end part of one metallic tube is closed with a clogging means providing a gas venting hole, and the other end part of the other metallic tube is connected with a gas injecting nozzle 7 to open the solenoid valve 5 under such a condition. The inert gas in the cylinder 1 is made under condition of reduced pressure with the pressure reducing valve 3 and passed through the solenoid valve 5 and injected into the metallic tube. At the time of injecting the inert gas into the metallic tube in such a way, the air containing oxygen existing in the metallic tube is vented outside the metallic tube from the gas venting hole provided in the clogging means fitted to the other end of one metallic tube and the inert gas is filled up in the metallic tube. Under this condition, the connecting parts of both metallic tubes are gas-welded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling the injection of an inert gas into a metal pipe at the time of welding, and more particularly, to welding a metal pipe such as a refrigerant pipe of an air conditioner or a pipe of a hospital or factory. Pertaining to a device in which an inert gas is injected into the metal tube at the time of welding in order to prevent the inner surface of the metal tube from being oxidized when the connection is made and an oxide such as an oxide film to fall into the metal tube. is there.

[0002]

2. Description of the Related Art When connecting a refrigerant pipe of an air conditioner or a metal pipe such as a pipe of a hospital or factory, gas welding with acetylene or the like is generally performed. That is, one end of one metal tube to be connected is inserted into the corresponding end of the other metal tube, and the connection between the two metal tubes is gas-welded. At this time, it is often the case that the inner surface of the metal tube near the welding point is oxidized and oxides such as oxide films fall into the metal tube. When such oxide falls into the metal tube, the oxide moves in the metal tube together with the refrigerant and other gases, clogs valves, thin tubes, capillary tubes (capillaries), etc., and breaks the insulation of the compressed air motor. This may lead to a situation such as an abnormality in the hydraulic system.

In order to prevent such a situation, nitrogen gas and carbon dioxide (carbon dioxide) are previously stored in a metal tube during welding.
It is considered that an inert gas such as the above should be injected and filled to prevent oxidation in the metal tube.

[0004] However, there is no known preferred device for injecting an inert gas into a metal tube during welding.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a preferable apparatus for injecting an inert gas into a metal pipe during welding.

[0006]

In order to solve the above problems, the present invention provides an apparatus for controlling the injection of an inert gas into a metal pipe at the time of welding described below.

(1) A gas blowing nozzle is attached to the inert gas cylinder via a pressure reducing valve and an electromagnetic valve, and the inert gas is injected into the metal pipe from the gas blowing nozzle. An inert gas injection control device for a metal pipe during welding (Claim 1).

(2) Preferably, the solenoid valve is controlled by a remote control device.

(3) A sensor for detecting a flame during welding is provided. When the sensor detects a flame during welding, the solenoid valve is opened, and an inert gas is injected into the metal pipe from a gas blowing nozzle. (Claim 3).

[0010]

[Action]

[Apparatus of claim 1] When injecting an inert gas into a metal pipe by the apparatus of claim 1 at the time of welding a metal pipe, one end of one metal pipe to be connected is placed in the corresponding end of the other metal pipe. The solenoid valve may be opened in a state where the solenoid valve is inserted, the other end of the one metal pipe is closed by a closing means having a vent, and the other end of the other metal pipe is connected to a gas blowing nozzle. In this case, the inert gas in the cylinder passes through the solenoid valve while being decompressed by the pressure reducing valve, and is injected into the metal pipe. When the inert gas is injected into the metal pipe in this way, the oxygen-containing air that was present in the metal pipe flows out of the metal pipe through the ventilation hole of the closing means attached to the other end of the one metal pipe. It is extruded and the metal tube is filled with an inert gas. In this state, the connection between the two metal tubes is gas-welded. At this time, since the inside of the metal tube is filled with the inert gas and there is no oxygen in the metal tube, there is no possibility that the inner surface of the metal tube near the welding portion is oxidized. Therefore, an oxide such as an oxide film does not fall into the metal tube. After the welding is completed, the inert gas in the metal tube is removed by a vacuum pump, compressed air or the like.

[0011] The electromagnetic valve is opened and closed by remote control.

In the apparatus according to the third aspect, when the sensor detects a flame during welding, the solenoid valve is opened, and an inert gas is automatically injected into the metal pipe from the gas blowing nozzle. You.

[0013]

Next, embodiments of the present invention will be described with reference to the accompanying drawings. The one indicated by reference numeral 1 is nitrogen gas,
A cylinder containing an inert gas such as carbon dioxide (carbon dioxide). A gas blowing nozzle 7 is attached to the cylinder 1 via a pressure reducing valve 3 and a solenoid valve 5.
The inert gas 13 is injected into the metal tubes 9 and 11. Reference numerals 15, 17, and 19 indicate connecting pipes.

A conventionally known solenoid valve is used. That is, the solenoid valve 5 is composed of a valve connected to the plunger and a coil for driving the plunger. When a current is applied to the coil, a magnetic force is generated, the plunger is operated by the magnetic force, and connected to the plunger. The transfer and shutoff of the inert gas 11 are controlled by opening and closing the valve.

The solenoid valve 5 may be operated by a tumbler switch, but is preferably controlled by a remote controller 21. As shown in FIG. 1, the remote control device 21 remotely controls a remote control relay 25 by a remote control switch 23 and opens and closes the solenoid valve 5 by the remote control relay 25.

Further, a sensor 27 such as a photoelectric tube for detecting a flame (gas flame) at the time of welding is provided. When the sensor 27 detects the flame at the time of welding, the solenoid valve is opened 5 and the gas blowout nozzle 7 An inert gas may be injected into the metal tube 9. The sensor 27 is attached to a connection pipe 35 described later as an example.

FIG. 2 shows an example of the use state of the inert gas injection control device according to the present invention. That is, the metal tube 9 and the metal tube 1
In connecting the first and second metal tubes 1 and 2 by welding, one end 9a of one metal tube 9 is inserted into the corresponding end 11a of the other metal tube 11,
In a state where the other end 9b of the one metal pipe 9 is closed by closing means 33 having a vent hole 31 and the other end 11b of the other metal pipe 11 is connected to the gas blowing nozzle 7 via the connection pipe 35. The solenoid valve 5 may be opened. In this case, the inert gas 13 in the cylinder 1 passes through the electromagnetic valve 5 in a state where the pressure is reduced by the pressure reducing valve 3, and is injected into the metal pipes 9 and 11. In this state, the connection between the metal pipes 9 and 11 is subjected to gas welding. Reference numeral 37 denotes a welded portion. The closing means 33 is, for example, a vinyl cap having the ventilation hole 31. The power supply of the apparatus of the present invention may be either DC or AC.

[0018]

As described above, according to the present invention,
An inert gas can be very easily and reliably injected into the metal tube during welding of the metal tube. Injection of an inert gas into the metal tube during welding of the metal tube prevents oxidation of the inner surface of the metal tube, so that oxides such as oxide films on the inner surface of the metal tube fall into the metal tube, and the oxide forms a refrigerant. The above-mentioned problems, such as moving in a metal pipe together with other gases and the like, clogging valves, thin tubes, capillary tubes (capillaries), breaking the insulation of the compressed air motor, and causing abnormalities in the hydraulic system, are solved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of an inert gas injection control device according to the present invention.

FIG. 2 is a sectional view showing an example of a use state of the inert gas injection control device according to the first embodiment;

[Explanation of symbols]

 Reference Signs List 1 cylinder 3 pressure reducing valve 5 solenoid valve 7 gas blowing nozzle 9 metal pipe 9a one end 9b other end 11 metal pipe 11a corresponding end 11b other end 13 inert gas 15 connecting pipe 17 connecting pipe 19 connecting pipe 21 remote control device 23 remote control switch 25 Remote control relay 27 Sensor 31 Vent hole 33 Closing means 35 Connection pipe 37 Welding part

Claims (3)

[Claims] A gas blowing nozzle is attached to a cylinder of an inert gas via a pressure reducing valve and an electromagnetic valve, and an inert gas is injected into the metal pipe from the gas blowing nozzle. Inert gas injection control device for metal pipe during welding. 2. An inert gas injection control device according to claim 1, wherein said electromagnetic valve is controlled by a remote control device. 3. A sensor for detecting a flame at the time of welding is provided. When the sensor detects the flame at the time of welding, the electromagnetic valve is opened, and an inert gas is injected into the metal pipe from a gas blowing nozzle. 2. The inert gas injection control device according to claim 1, wherein: