DE8535215U1 - Device for controlling a protective gas and/or purge gas flow - Google Patents

Description

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MTU ENGINE AND TURBINE UNION
MUNICH GMBH

Munich, 24.2.1987

Device for controlling a protective gas and/or purge gas flow

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The invention relates to a device for controlling the shielding gas and/or purge gas supply to a welding torch and a root protection device, in particular for tungsten ^1S inert gas welding.

When joining high-quality workpieces and components, e.g. made of superalloys, titanium alloys, stainless steel, etc., it is necessary to protect the weld seam, especially its root, from oxygen ingress, and in the case of titanium, also from nitrogen ingress, in order to reduce chemical reactions, oxidation phenomena and their consequences, such as embrittlement, risk of breakage, etc. There are basically two options: either to carry out the welding in a self-contained welding chamber that has an inert gas atmosphere (e.g. glove box/shielding gas bell) or to form a type of displacement protection bell made of shielding gas on the weld seam itself in the burner area or the area surrounding it, in particular by directly flowing onto the top of the seam. The top of the seam is also protected by

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The weld is protected from welding gas, in particular by using a device that creates a gas chamber in the root area of the weld. This chamber must be sufficiently flooded and flushed before welding work begins.

Since the protective gases are usually expensive noble gases such as argon or helium, the second method mentioned above is often preferred, however

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Shielding gas or purge gas can be the same or similar gases or gas mixtures.

7.The object of the present invention is to.

to create a device for controlling the supply of protective gas and/or purge gas to a welding torch and the respective root protection device, in which the gas consumption is reduced by specifically controlled gas flow times/on the other hand the safety against oxidation or chemical reactions for the weld seam and thus for the parts to be joined is increased.

This object is achieved by the features listed in the characterizing part of claim 1. Further features can be found in the description and drawing of an embodiment, without the invention being limited to this, in particular not to the specific type of welding torch or welding process. Combinations and sub-combinations of the described, illustrated and claimed features, including features known per se, also fall within the scope of the invention.

Show it:

Fig. 1 is a schematic representation of the

control unit,

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Fig. 2 a block diagram of the control unit

in connection with the welding machine,

Fig ₄ 3 _v the welding torch with the outlet pipe for the shielding gas supply and the

associated root protection device

The control unit has a housing 1 and a time controller 2 for the pre-flow time and a time controller 3 for the post-

jQ flow of the protective gas and rinsing gas to the weld seam. 4 denotes the control electronics, which contains switching relays and will be explained in detail later. 5 denotes a controllable solenoid valve and 6 a pressure switch for gas flow or discharge.

■jc blocking. 7 indicates a signal lamp. Several signal lamps or other displays can also be provided. 8 indicates the control current line for releasing the welding current in the welding machine. The welding current is controlled in particular via a foot switch

r,Q 13, which is connected via line 9 to the control electronics 4, which contains the time controller, and to the welding machine 12, on the one hand. A shielding gas line 10 leads from the welding device 12 to the torch 15, and a purge gas line 11 leads to the root protection device. An additional line 16 can be used as a reserve line or bypass to another location. A further solenoid valve 17 can be arranged in the welding device in the supply line to the torch. In addition to the on/off switch 18 for the welding current, the welding device also provides

₃ Q mains and from the line 19 the pulse generator 20. In the time control in the housing 1 it is particularly clear from Fig. 2 that the electronics, in addition to the RC elements and/or diodes, a relay 4a for blocking or releasing the welding current to the line 8 to

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welding machine and the electromagnet 5a for the solenoid valve 5. A manual valve 21 can be installed in the main line 22 in front of the solenoid valve 5 in case the time control electronics fails or its power supply is interrupted.

B supply 23, the latter can be from a mains such as an alternating current mains of normal frequency or from a low-voltage source such as a battery, while the power supply of the welding device 12 at 19 requires a mains of at least 220 to 380 volts and 50 Hz. Welding transformer and pulse generator 20 as well as pulse control 14 are of a known type.

From Fig. 3 it can be seen a weld seam 24, the TIG torch 15 with W electrode 29 and a mouth pipe 25 of a ceramic nozzle 28 of the shielding gas supply line which places a shielding gas bell 26 over the area of the weld seam that connects the workpieces 30, 31.

The functions of the welding machine with shielding gas and/or purge gas time control are as follows:

There is a workpiece with a suitable root protection device. The welder sends a switching impulse to the pre-flow time controller 2 via his foot switch 13, the purge gas and later root shielding gas flow 27 is released via the solenoid valve 5. This floods the purge gas chamber, whereby the welding machine or the torch is not yet ready for ignition. Only when the pre-flow time has expired does the control device signal readiness for ignition with a clearly visible light signal 7. The welder can now ignite his torch as normal and start welding. If the welding current is switched off via the _foot switch 13, the post-flow time controller 3 comes into action. This controller keeps the shielding gas flow open via the solenoid valve control 5 until the part has cooled down sufficiently and a protective

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gas cover is no longer necessary. This post-flow time can be determined experimentally over a few tests and set on the post-flow time controller. If the welder starts work again within the post-flow time (changing electrodes, new filler wire, etc.), the welding can be started again immediately. If the post-flow time controller switches off, the welding must first be pre-flooded again (pre-flow time controller).

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24.2.1987

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Housing » · t » · · ... « t III Preflow time controller Post-flow time controller 1 Switching relay 2 Relay (electromagnet) 3 Gas valve control 4 magnetic valve 4a Supply pressure sensor 5 Signal lamp 5a Control current line 6 to the welding machine 7 Pulse control cable (for foot switch) 8th Shielding gas supply line Flushing or root protection gas line 9 Welding machine 10 Foot switch 11 Welding current control 12 Torch (TIG) 13 Reserve line 14 magnetic valve 15 On/off switch 16 Power line (to 12) 17 Impulse generator 18 Valve (manual) 19 Main line 20 Voltage source (mains connection) 21 Weld 22 Mouth (v. 15) 23 Protective gas bell 24 Root protection 25 Ceramic nozzle 26 Electrode (W) 27 Workpieces 28 29 23.2.1987 30,31 ESP-842

Claims (9)

-1 zw/fh MTU MOTOREN- UND TURBINEN-UNION MÜNCHEN GMBH Munich, 2.12.1986 Protection claims 15 1. Device for controlling the supply of shielding gas and/or purging gas to a welding torch and, if applicable, a corresponding root protection device in "- ¹ a Wolfrair.-Ir.ert gas welding torch, characterized in that it comprises in a housing (1) a control electronics (4), time control elements, switching means (relay 4a) and a solenoid valve (5a) in a line (10) to the torch (15) and/or (11) for root protection. device (24) and a lock as a mutual locking of the switching means (4a) for the welding current and the solenoid valve (5a) for controlling the shielding gas supply. 2. Device according to claim 1, characterized in that it comprises in the housing, in addition to the means for controlling the welding current and the protective gas supply, an output for a power line (8) for switching a welding device or welding machine (12). 35 ESP-842 ■ · * m -2- 3. Device according to claim 1 or 2, characterized in that the housing contains an input for a power line (9) to a foot switch (13). 4. Device according to claim 1, characterized in that the housing (1) of the control electronics contains a microprocessor that operates independently of the operator. IQ 5. Device according to claim 1, characterized in that a manual ^valve (5a) is permanently installed in the housing for emergency use. 6. Device according to claim 1 ₁ , characterized in that a pressure switch (6) for gas flow or blocking is contained in the housing (1). 7. Device according to claim 1, characterized in that the housing (1) contains an indicator (7) for the readiness of the burner to ignite. 8. Device according to claim 1, characterized in that in the housing (1) a battery or other voltage source or a voltage source connection (23) is present. 9. Device according to claim 1, characterized in that a consumption measuring device or - Flow meter (10) for protective gas and/or purge gas is firmly connected. ESP-842 2.12.1986