RU2845065C1 - Multifunctional vacuum furnace - Google Patents

Abstract

FIELD: furnaces.

SUBSTANCE: invention relates to a multifunctional vacuum furnace. Furnace consists of a water-cooled body, a collapsible metal frame of the furnace, a thermally insulated working zone of the furnace, inside of which there is a removable collapsible crucible for heat treatment of carbon fibre or charge, hydraulic cylinders driven by a hydraulic station, furnace body both faces are equipped with two water-cooled covers to be opened by said hydraulic cylinders. Said thermally insulated working zone accommodates crucible heating system. At that, the furnace is equipped with a vacuum-gas system installed on the furnace frame, a system for absorbing released gases and vapours, natural gas supply system, natural gas sieving output system or excess natural gas afterburner system, housing water cooling system, crucible accelerated cooling system and control system, furnace is equipped with current leads for heating crucible or charge by means of heating system, oil-type vacuum pump with possibility of quick oil replacement and standby vacuum pump.

EFFECT: possibility of carrying out several technological processes (intermediate annealing, pyrolytic sealing, final annealing) on one equipment, which makes it universal, since such a combination of technological operations leads to a reduction in the process cycle of up to 6-7 days, which is quite significant when working with carbon materials, and also saves time by excluding additional unloading/loading of equipment, which is accompanied by complete cooling of the furnace and repeated raising to previously achieved temperatures.

1 cl, 5 dwg

Description

Field of technology

The invention relates to the field of heat treatment, in particular to horizontal-type electric vacuum furnaces for pyrolytic compaction of products made from carbon-carbon composite material (CCCM) and chopped carbon fiber loaded into a crucible.

State of the art

A multifunctional vacuum electric furnace is known from the prior art, comprising a heater body, hydraulic means, an air recirculation system with water cooling, an external circulation pipeline with air cooling, a fire door and an inspection window located on the heater body, wherein a pressure sensor is installed on the next hydraulic axis, and on the mounting platform, which is the upper and two lower hydraulic axes are passed through a low-vacuum seal, a high-vacuum installation is separately respectively connected to the heater body (see CN 201145473, 05.11.2008).

The disadvantages of the above-mentioned patent are the low permissible temperature in the furnace of 1300°C and the small internal volume of 0.06 ^m3 of the heat treatment zone, as well as the lack of the ability to regulate the heating rate.

The prior art also discloses a vacuum furnace comprising an electric furnace housing, a vacuum system, a power supply device, a water cooling system, a hydraulic system, a pneumatic system, an electrical control system, an intermediate frequency power source, the electric furnace housing comprises a copper roller, a quartz tube and a temperature sensor, the control module and the induction coil are located in the cavity of the electric furnace housing, the copper roller and the quartz tube are located in the lower part of the electric furnace housing, and the induction coil is located in the middle part of the quartz tube (see CN 204963538, 13.01.2016).

The disadvantages of the above-mentioned patent are its narrowly specific purpose and the impossibility of using it for pyrolytic compaction processes of products made of carbon-carbon composite material (CCCM) and chopped carbon fiber.

Disclosure of invention

The technical results of the claimed invention are the possibility of carrying out several technological processes (intermediate firing, pyrolytic compaction, final firing) on one equipment, which makes it universal, since such a combination of technological operations leads to a reduction in the technological cycle to 6-7 days, which is quite significant when working with carbon materials, and also saves time by eliminating additional unloading/loading of equipment, which is accompanied by complete cooling of the furnace and repeated rise to previously achieved temperatures.

The above technical result is achieved by a multifunctional vacuum furnace consisting of a water-cooled body, a dismountable metal furnace frame, a heat-insulated furnace working area, inside which a removable dismountable crucible is installed for heat treatment of carbon fiber or charge, hydraulic cylinders driven by a hydraulic station, at both ends of the furnace body there are two water-cooled covers that open by means of said hydraulic cylinders, inside the heat-insulated working area there is a crucible heating system, while the furnace is equipped with a vacuum-gas system installed on the furnace frame, a system for absorbing released gases and vapors, a natural gas supply system, a natural gas sifting system or a system for exhausting excess natural gas, a water-cooling system for the body, an accelerated crucible cooling system and a control system, the furnace is equipped with current leads for heating the crucible or charge by means of a heating system, an oil-type vacuum pump with the possibility of quick oil change and a backup vacuum pump, a multifunctional a vacuum furnace consisting of a water-cooled body, a dismountable metal furnace frame, a heat-insulated furnace working area in which a removable dismountable crucible is installed for heat treatment of carbon fiber, the furnace is equipped with two water-cooled covers at both ends, opened by means of hydraulic cylinders driven by a hydraulic station, a charge heating system is located inside the heat-insulated working area, while heating is performed by electric current, the supply of which is carried out through current leads, and the vacuum in the furnace and the supply of inert gas are performed by means of a vacuum and gas system through a branch pipe - with cooling, the possibility of routine cleaning, gas supply through a gas pipe, while the furnace also includes an oil-type vacuum pump with the possibility of quick oil change and a backup vacuum pump.

Brief description of images

Fig. 1 shows a general view of a multifunctional vacuum furnace.

Fig. 2 shows view A-A of a multifunctional vacuum furnace.

Fig. 3 shows the view B-B of the multifunctional vacuum furnace.

Fig. 4 shows view "B" of a multifunctional vacuum furnace.

Fig. 5 shows the "G" view of a multifunctional vacuum furnace.

Implementation of the invention

The electric vacuum furnace is designed for pyrolytic compaction of products made of carbon-carbon composite material (CCCM) and chopped carbon fiber loaded into a crucible at an operating temperature of 980+20°C with natural gas supply, as well as for carrying out high-temperature heat treatment processes at temperatures up to 2350÷200C according to a set schedule in order to complete the production of friction composite carbon materials.

Heating of materials can be carried out in automatic and manual modes.

The automatic mode is carried out at a given temperature using feedback from the control device or at a given power. The manual mode is carried out using power regulation. The control device is a pyrometer.

Heating of materials is carried out in a vacuum in a furnace.

The processes of pyrolytic compaction of high-temperature heat-treated products can be performed sequentially, without removing the products from the furnace.

The furnace temperature, outer wall temperature, heating rate, furnace vacuum and gas supply parameters are monitored throughout the process, displayed on the monitor screen, recorded and archived.

The vacuum furnace includes the following systems:

- a system for heating the cage;

- vacuum-gas system;

- a system for absorbing emitted gases and vapors;

- natural gas supply system;

- a system for removing natural gas from the screen or a system for burning excess natural gas;

- water cooling system;

- accelerated cooling system for the cage;

- removable, collapsible crucible for heat treatment of carbon fiber;

- loading and unloading system for the cage;

- control system.

The electric vacuum furnace (Fig. 1) consists of a water-cooled body (1) with external dimensions D=2450 mm, L=3245 mm and an internal volume of 14 cubic meters.

The housing is arranged horizontally. The geometric dimensions of the insulated working area of the furnace are 1100×1100×2700 mm, the geometric dimensions of the crucible for heat treatment of carbon fiber are 900×900×2600 mm. The maximum charge weight is ~1500 kg.

At both ends the furnace is equipped with two water-cooled covers (2), which are opened using hydraulic cylinders (9), driven by a hydraulic station (10).

The heating system for the charge (4) is located inside the thermally insulated working area. The heating system for the charge provides:

maximum temperature, °C 2400 operating temperature, °C 2300 adjustable heating speed up to, °С 350 temperature difference along the height of the cage, no more than, °C 20

Heating is performed by electric current. Current is supplied through current leads (5).

The thermal insulation material is protected by composite carbon material to prevent destruction.

Vacuum in the furnace and inert gas supply are provided by vacuum and gas systems. The vacuum and gas system provides:

absolute pressure no more than, Pa 100 leakage rate no more than, Pa/h 40

Vacuum is provided through the outlet pipe (6) - with cooling, the possibility of routine cleaning, and gas supply through the gas pipe (7).

All the listed devices are assembled on a collapsible metal frame of the furnace (8).

In addition to the above, the furnace includes an oil-type vacuum pump with the ability to quickly change the oil, and a backup vacuum pump.

Switching to a backup pump in the event of failure of the main one is carried out automatically or by the operator.

Each cooling line is equipped with a water presence and temperature sensor.

If there is no water or if the threshold temperature is exceeded (set in the settings), the operator is notified by sound and light signals and a pop-up interface window, allowing the process to be transferred to manual control or stopped. If the plant operator does not take any action, the process is automatically stopped (the time after which the process will be automatically stopped is set in the settings).

The water cooling system ensures that the temperature of the outer wall of the housing does not exceed 50°C.

The accelerated cooling system provides forced cooling of the charge with inert gas ( _N2 , Ar) in a closed cycle with the ability to regulate the cooling rate in the range from 200 to 400°C/h.

The system for absorption of emitted gases and vapors ensures absorption of all emitted substances (carbon monoxide, sulfur, oxygen, hydrocarbons, etc.) without releasing them into the environment. The total amount of volatile products can be up to 5% of the mass of the workpieces (25-32 kg), including: carbon monoxide - up to 3%, hydrocarbons - up to 1.5%, sulfur - up to 0.5%, oxygen - up to 0.02%.

The loading and unloading system ensures horizontal loading and unloading of blanks, and in the case of carbon fiber heat treatment, unhindered loading and unloading while meeting occupational health and safety requirements.

The control system provides:

- operation of the furnace in both automatic and manual (setup) control modes;

- necessary interlocks that prohibit the operation of the furnace in case of abnormal situations or erroneous actions by the operator;

- switching off the furnace in safe mode in case of an emergency with simultaneous notification of personnel using sound and light alarms.

The control system ensures continuous monitoring of technical and technological parameters of the process with the ability to record and archive them.

The declared multifunctional furnace operates as follows. The full cycle of processing materials in the furnace consists of several stages:

- Furnace loading. Depending on the type of workpieces, loading is carried out manually or using a crane beam through the end covers of the furnace, opened by a hydraulic drive with the heat-insulating covers open and the front and rear graphite heater panels removed.

- Nitrogen purging during thermal stabilization or 5 mm Hg vacuum during firing and pyrolytic compaction. These operations are carried out with the end caps of the furnace closed.

- Heat treatment of blanks. Heat treatment is carried out for a long time from 13 to 16 hours, at different temperatures and heating rates. Heating is carried out gradually at the required rate and time holding at each temperature interval. After heating is completed, holding is carried out.

- Cooling. Cooling is carried out in two stages: passive, up to 900°C and in a nitrogen environment up to 200°C.

- Depressurization and unloading of the furnace. The end covers of the furnace are opened after the blanks have cooled to 200°C, then the heat-insulating covers are opened and cooling to 60°C occurs, and only after that unloading begins. Depending on the type of blanks, unloading is carried out manually, using a crane beam or a stacker. After unloading, the current leads, pyrometric tubes, body and furnace covers are cleaned of condensed deposits with a brush and scrapers. Then it is necessary to vacuum the working area of the furnace from remaining dirt and sweep the working area around the furnace, close the furnace covers.

Claims (1)

A multifunctional vacuum furnace consisting of a water-cooled body, a dismountable metal furnace frame, a heat-insulated furnace working area, inside which a removable dismountable crucible is installed for heat treatment of carbon fiber or charge, hydraulic cylinders driven by a hydraulic station, at both ends of the furnace body there are two water-cooled covers that open by means of said hydraulic cylinders, a crucible heating system is located inside the heat-insulated working area, while the furnace is equipped with a vacuum-gas system installed on the furnace frame, a system for absorbing released gases and vapors, a natural gas supply system, a natural gas sifting outlet system or an afterburning system for excess natural gas, a water-cooling system for the body, an accelerated crucible cooling system and a control system, the furnace is equipped with current leads for heating the crucible or charge by means of a heating system, an oil-type vacuum pump with the possibility of quick oil change and a backup vacuum pump.