1. Purpose of the equipment. Technological processes in which equipment is used.

The «USKS-26» plant is designed for automatic arc welding of body products made of chemically active metals and alloys in a controlled environment with a non-consumable tungsten)electrode.

The maximal diameter of welded products is 500 mm, the maximal height is 500 mm, and the maximal weight with equipment is 50 kg.

The chamber contains: an electrode holder, a current lead, a brush holder, a rotator with a faceplate and the product itself intended for welding.

The vacuum system creates a preliminary vacuum of 2.6 Pa (2*10-2 mm Hg) in the chamber. After this, argon enters the chamber to an excess pressure of 0.02 MPa (0.2 atm). The chamber with the loaded product is ready for welding.

The operator console and control cabinet are used to control the welding process. Equipment in the cabinet controls the operating pressure of argon in the the chamber. The safety valve maintains pressure in the chamber. It is located on the vacuum system manifold.

The “VSVU-400” power source supplies energy for the welding arc.

Two viewing windows with light filters are designed for visual observation. Additional side windows serve to illuminate the workspace from external lights.

A pneumatic cylinder lifts the chamber hood vertically upward for loading and unloading products. The pneumatic cylinder is pivotally connected to a guide, which has the ability to move progressively in the body of the lifting mechanism. The upper part of the guide is rigidly connected to the lifting part of the vacuum chamber.

2. Features of the physical processes used.

Argon arc welding in an inert gas environment is widely used for joining non-ferrous metals and alloy steels, especially of small thickness. Otherwise, additives are used.

Additives for argon-arc welding are metals of higher density and lower melting point, which are sprayed by surfacing and act as a connecting “layer”.

In this case, welding is only possible in an environment of inert gases or carbon dioxide, since the entry of air will lead to spattering of soft molten metals.

3. Technical description. Design features. Equipment advantages.

The «USKS-26» plant consists of the following main components:

- Vacuum chamber;

- Base;

- Electrode holder

- Lifting mechanism;

- Rotator;

- Vacuum system;

- Inert gas supply system;

- Electrical wiring;

- Welding power source;

- Control system.

3.1 Vacuum chamber

The chamber is a vertically located sealed cylindrical container with a rounded top. The chamber is made of stainless steel. There are two viewing windows on the front side of the chamber, and two windows on the sides to illuminate the interior of the chamber with external lamps.

The chamber contains: a rotator faceplate, a product for welding, an electrode holder, a current lead and a brush holder.

3.2 Foundation

The base is a rectangular welded frame structure made of square pipes. A tabletop is installed on the upper frame, to which the base of the vacuum chamber, a rotator, chamber clamps, a vacuum chamber lifting mechanism, lamps and a vacuum system manifold are attached.

The sides of the base have removable steel panels. There are hinged steel doors installed at the front and rear for easy access when servicing the vacuum system, pneumatic system, rotator drive and electrical wiring.

To adjust the position of the plant table in the horizontal plane, the base has screw adjustment supports with the ability to be fixed in the desired position with a lock nut.

3.3 Electrode holder

The electric holder is designed to adjust the tungsten electrode to the joint being welded. The electric holder consists of a vertical supporting post with a rotating and retractable bracket with a rotating head into which a welding electrode is fixed through a collet.

The electrode is adjusted to the joint manually with the chamber open.

3.4 Lifting mechanism

A lifting mechanism is provided to lift, lower and fix the vacuum chamber in the uppermost position.

The pneumatic cylinder for lifting the chamber is equipped with a pneumatic brake, which automatically fixes the position of the rod in a given position and ensures that the vacuum chamber is held in the current (raised) position in the event of an emergency power outage or air failure. The brake release occurs when air is supplied to the brake cavity.

Signals about the extreme (upper and lower) positions of the vacuum chamber are transmitted to the plant’s automatic control system from two position sensors installed on the pneumatic cylinder body.

3.5 Rotator

The rotator is designed to rotate the product with equipment installed on the faceplate at a given speed during the welding process. To reduce the dimensions of the height of the installation and the vacuum chamber, the spindle has a cylindrical cavity for recessing part of the part to be welded beyond the plane of the faceplate.

3.6 Vacuum system

The vacuum system is designed to create a preliminary vacuum in the chamber before inert gas inning. The vacuum system is located inside of the base of the plant. The system includes: an oil-free vacuum mechanical pump, pneumatic vacuum valves, vacuum sensors, a vacuum gauge, and an excess pressure relief valve.

Using a vacuum system, a preliminary vacuum of 2.6 Pa (2*10-2 mm Hg) is created in the chamber. When the specified vacuum is reached, argon is injected into the chamber from the argon supply system to an excess pressure of 0.02 MPa (0.2 atm.).

In an emergency (power outage, interruption of air supply), the vacuum chamber is cut off from the pump by vacuum valves with a pneumatic drive.

3.7 Inert gas supply system

The argon supply system is designed to supply inert argon gas at the required pressure into the vacuum chamber before the process of welding of the product with a non-consumable tungsten electrode.

Preliminary adjustment of the required inert gas supply pressure is carried out manually in two stages: rough adjustment - on the gas cylinder reducer and fine adjustment - on the pressure regulator according to the pressure gauge.

Inert gas is injected into the chamber through a vacuum valve at the command of the installation’s automatic control system.

The installation has a system for monitoring and measuring the argon pressure in the chamber.

It is possible to equip the installation with a system for purifying inert gas from mechanical impurities formed during the welding process with a closed cycle without depressurizing the vacuum chamber.

Excess pressure that arises in the chamber during the welding process or when inert gas is introduced before welding is relieved by a safety valve.

3.8 Electrical wiring

Electrical wiring is designed to provide power to control circuits of mechanisms with electric drives. Electrical wiring lays in boxes, providing easy access to it during maintenance and repair work. Modern multi-core cables are used in electrical wiring.

3.9 Power supply

The universal rectifier “VSVU-400” is intended for powering of the plant for automatic and manual arc welding of heat-resistant steels, stainless steels and titanium alloys in an argon environment with a non-consumable electrode, as well as for welding carbon steels with coated electrodes with a compressed, continuous and pulsed arc.

3.10 Control system

The welding process is controlled from the operator's console or from the remote control. Starting and protective equipment is located in the control cabinet. The control system provides:

- automatic control of the welding process from the controller;

- manual and automatic control of the vacuum system;

- injection of inert gas;

- air intake;

- pneumatic system control.

The arc length is set manually by the welder.