1. Purpose of the equipment. Technological processes in which equipment is used.
The vacuum arc plant “833DM” is designed for melting titanium using the consumable electrode method and its subsequent casting into molds up to 120 kg.

2. Features of the physical processes used.
The vacuum electric arc melting plant “833DM” is used for melting titanium alloys.
Vacuum-arc plants “833DM” make it possible to obtain such advantages as a low concentration of gases and non-metallic inclusions in the alloy, high homogeneity and density of the ingot, and significantly improve the properties of the metal.
It is possible to achieve special conditions in vacuum plants: the highest temperatures and high pressures. Temperature is controlled either manually or using a regulator.

3. Technical description. Design features.
The plant consists of the following main mechanical components:
- Chamber;
- Mechanism for moving of the electrode;
- Crucible with rotation mechanism;
- Filling device;
- Container;
- Centrifugal machine;
- Vacuum system;
- Gas injection system;
- Сontrol system.

3.1. Chamber
The vacuum chamber is designed to accommodate mechanisms and devices for implementing of the technological process of skull melting: a contact pad for welding an electrode, a crucible, a consumable electrode, a container for casting molds mounted on a centrifugal table. The chamber is a water-cooled cylinder made of stainless steel and two water-cooled lids.

3.2 Electrode movement mechanism
The electrode moving mechanism, installed vertically on the upper branch pipe of the chamber, serves to carry out the working supply of the electrode during melting and quickly throw the electrode up at the end of melting. The mechanism consists of metal structures (columns), a gearbox with an electric motor, a coupling, a feed screw, a carriage, a pneumatic cylinder, a water-cooled source with flexible communications for supplying electricity, cooling water, and supplying compressed air to the pneumatic cylinder.
The plant uses a power source, “IDP-20” to power the electric arc. To minimize power wiring from the electrode to the power source, the plant is provided with a special separate trestle.
To connect the power source, busbars with flexible current leads are fixed to the column.
The downward movement of the rod during supply of the consumable electrode is performed by an asynchronous electric motor with a frequency drive.
During melting, the electrode has a negative electrical charge, and the skull crucible has a positive charge.

3.3 Crucible with rotation mechanism
A crucible with a rotation mechanism is used to fuse liquid metal with an electric arc from a consumable electrode and pour the metal into molds. It is a graphite container shaped like a truncated cone. The crucible is fixed in a welded water-cooled casing with rotating trunnions. The trunnions in the chamber holes have vacuum seals.

3.4 Filling device
The filling device (tray) is installed on a vacuum chamber above the container with the casting mold.

3.5 Container
The container is designed for placing of casting molds; it is installed and secured on the table of a centrifugal machine. The container is a cylindrical form with a lid. The lid has a central hole for pouring metal into the mold. A rotary manipulator is used to install the assembled container into the chamber. The bottom of the container has a landing hole.

3.6 Centrifugal machine
The centrifugal machine consists of a centrifugal table and a drive. The table and drive are installed on independent foundations. The drive of a centrifugal machine consists of a frame, an electric motor and a belt drive. The frame of the centrifugal table is a welded structure that is not rigidly connected to the chamber. The seal between the frame and the table is a flat ring made of vacuum rubber, protected from metal splashes by a special welded ring.
The drive of the centrifugal machine is equipped with an asynchronous motor and a frequency drive for stepless speed control.

3.7 Vacuum system
The plant is equipped with a modern vacuum system, required measuring tool and pneumatic valves for evacuation of the melting chamber.
The vacuum system of the plant provides two pumping modes: fore-vacuum and booster. The forevacuum pumping mode of the chamber is provided by mechanical and rotary pumps. The booster pumping mode is provided by steam ejector and mechanical pumps.
Pneumatically driven valves ensure safe operation of the vacuum system during power outages. The pneumatic system includes an air preparation unit and a receiver.

3.8 Gas injection system
The gas inlet system is designed to inject inert gases into the vacuum chamber during mold cooling and in an emergency.

3.9 Control system.
The control system of the “833 DM” plant is built according to the PC-PLC structure and includes a personal computer (upper level), a programmable logic controller (lower level). The controller controls the operation of the system at the lower level.
The controller performs the functions of technological process control, the computer performs only the terminal control task - visualization of the state of the furnace elements, storage of process history files, events and errors.
The plant control system performs the following functions:
- control of the operation of the vacuum system in automated, manual and adjustment modes;
- maintaining with high accuracy the main parameters of the vacuum arc melting process: arc current, speed of vertical movement of the electrode;
- automatic measurement of leakage of the working chamber;
- possibility of recording the parameters of the melting process and archiving the results.
The top-level software of the control system provides:
- processing information about technological parameters and the state of elements of the technological system;
- registration and storage of technological process parameters with reference to real time;
- formation of archive and emergency files, event file;
- converting the generated database into Excel table format;
- output to an electronic medium of a passport for the melting process carried out for subsequent printing by a printer.
Setting control actions and entering programmable process parameters displayed on the monitor is carried out using operator commands.