Experimental furnace heating wire classification

Including iron-chromium alloy heating wire and nickel-chromium alloy heating wire into two categories. The former is a ferritic alloy tissue, which are austenitic alloys. In addition, there are some special purposes such as tungsten filament heating alloy wire, molybdenum wire and other laboratory furnace according to different purposes, to different temperatures, choose a different electric wire.
Laboratory furnace with electric wire electric iron chrome aluminum alloy material is characterized by:
1. Use of high temperature, such as HRE iron-chromium alloy wire in the atmosphere maximum temperature up to 1400 ℃, which is the laboratory furnace maximum temperature can reach 1,400 degrees, if you need to design more than this temperature laboratory furnace, you need to select another The electric wire;
(2) long life;
3 Allow the surface of the load is large;
4 good oxidation resistance, and its oxidation to generate AI2O3 film has good chemical resistance and high electrical resistivity, specific gravity less than nickel-chromium alloy, high resistivity.
5 sulfur resistance is good;
6 prices significantly lower than nickel-chromium alloy;
7 disadvantage is that as the temperature increases, the performance of plastic, high temperature strength is low.
Laboratory furnace nickel-chromium heating wire is characterized by:
1, high strength at high temperatures;
(2) long-term use and then cooled down, the material does not become brittle;
3 fully oxidized nickel alloy ming the radiation rate ratio Fe-Cr alloy high;
4 non-magnetic;
5 In addition to the atmosphere of sulfur, the better corrosion resistance.
Laboratory furnace alloy heating wire shortcomings
Alloy heating wire is the most widely used, the largest amount of heating materials. Its disadvantage is its working state is very high temperatures (hot state), prone to oxidation in air blown reaction; electrothermal energy conversion aspects from analysis due to energy loss leaving visible light generating section; electric wire is often Use a spiral state, power is generated when inductance effects.

Vacuum hot pressing furnace use Common Faults and exclusion method

High vacuum pumping on but does not leak ( muffle furnace mean value of the vacuum table for a long time does not move)
Possible causes:
1. High vacuum gauge tube aging
2. Diffusion pump oil aging
Solution: Replace the vacuum gauge; replacement diffusion pump oil.
But not on the low vacuum pumping does not leak (mean value of the vacuum table for a long time does not move)
Possible causes:
1 low vacuum current regulatory work incorrectly.
2. Mechanical pump oil aging
Solution: Adjust vacuum gauge tube current; replacement of mechanical pump oil.
Thermocouple automatic access failure, warning lights alarm
Possible causes:
1. Inner and outer limit failure.
2. Out of the motor does not turn.
Solution: Adjust or replace the external stopper; tests whether the motor has been broken, such as the replacement of the same type of motor bad. (Note) within the furnace limit should be observed before heating indicator light should be lit.
After a period of time the temperature does not rise up
Possible causes: heater resistance value becomes larger.
Solution: According to instructions to transfer large instrument output power; serious aging can only be replaced with a new heater
Incase control panel lights are on and the police overcurrent
Possible causes: heater shorted
Solution: Open the lid heater observe whether there is a short circuit, troubleshooting.
Over-temperature alarm and alarm lights on
Possible causes:
1. Over-temperature furnace
2. Instrument is set incorrectly
Solution: Press the manual reset over-temperature alarm parameters
Without water is lit and the alarm
Possible causes:
1. Valve did not open
2. Water pressure is too low
Solution: Open the valve; increase water pressure.

Mesh belt type continuous heat treatment furnace introduced:

Mesh belt type continuous heat treatment furnace electric heating, non-connected to the shape of parts placed on the network belt drive mesh belt running through the drive mechanism, so that the workpiece to be processed continuously through the furnace, step-by-step through the replacement, the warm-up heating, the average temperature, insulation, cooling process, so as to achieve the purpose of bright heat treatment. Mesh belt type continuous heat treatment furnace according to the type of temperature and external configuration, mainly applied to the metal material parts by bright annealing and sintering of metal powder.
Mesh belt type continuous heat treatment furnace working principle:
Mesh belt type continuous heat treatment furnace is the use of intermittent forward network with the workpiece through the temperature-controlled heating zones, and then fall into the quenching tank by the elevator automatically remove the mesh belt washing machine for degreasing cleaning, drying, and finally transport to mesh belt furnace for tempering continuous heat treatment production line. It in a controlled atmosphere heat treatment process of hardening, a thin layer carburizing, carbonitriding infiltration. During the heat treatment, the workpiece between the collision, a balanced manner through the furnace was heated, together with the role of the controlled atmosphere to prevent the incursion of air furnace. Therefore, the treatment, the workpiece surface is smooth, no decarburization, uniform hardness, deformation is small, high quality. The production line has a high degree of automation, easy to adjust the parameters, low labor intensity, do not pollute the environment, energy conservation, etc..
Mesh belt type continuous heat treatment furnace Scope:
Mesh belt type continuous heat treatment furnace for heating temperature quenching, carburizing and carbonitriding and subsequent tempering. Widely used in mass production of small parts such as fasteners, chains, bearings, small weapons, hardware tools, elastic components, sewing machines, bicycles, car and motorcycle parts the smooth hardening under protective atmosphere or thin carburizing and carbonitriding permeation. According to the different kinds of steel, can be water, oil or molten salt quenching tank quenching agent.

Selection of the heating element resistance furnace

A. Select the basic elements of heating elements
1. According to the temperature: (heating element temperature = furnace temperature +100- -200 degrees)
General furnace temperature is less than 1000 degrees, the choice of NiCr, FeCrAl
Furnace at 1000-1200 degrees, use FeCrAl (Cr27Al7Mo2)
Furnace temperature greater than 1200 degrees, the choice of pure metal or nonmetal
2. According to structural characteristics of the furnace
3. Treatment of the workpiece according to the situation
4. High radiation efficiency
5. Convenient source
Two. Select the heating element should have the following properties
High resistance, cross-sectional area, good mechanical strength, thermal expansion coefficient some chemical stability
III. Heating element surface load (W) select
1. W greater the shorter the life
2. High resistance furnace temperature, corrosive atmosphere, W is to take a small
3. Heating element with shield (such as car heaters, heating elements in the furnace under the floor), W is to take a small
4. Furnace can be ventilated, W whichever is greater (can be increased 30-50 percent)
5. Ribbon elements, W whichever is greater (can be increased 30-50 percent)
6. Replace difficult element, W to take a small
Four. Alloy element surface load Recommend
Material heating element temperature (unit: ° C)
Less than 1000 less than 1,100 less than 1200
OCr25Al5 1.6 - 1.8 1.2 - 1.5 0.81
Cr20Ni80 1.1 0.5 - 0.8
Cr15Ni60 0.8
CrAl7Mo2 at 1200-1300 degrees, W is taken 1.6-1.8
Five. Pure metal surface load
W, Mo, Ta less than 1800 °, W is taken 10-20W/cm2
Graphite W Less than 15-20W/cm2

 

Vacuum atmosphere furnace maintenance required

Environmental testing equipment variety, but the most widely used environmental test equipment for the heat, cold, heat vacuum atmosphere furnace. Hot and cold impact testing machine, for example, to talk about the vacuum atmosphere furnace construction and some of the common faults and troubleshooting.
Some vacuum atmosphere furnace and troubleshooting common faults:
1 in the high-temperature tests, such as temperature changes reach the test temperature value, you can check the electrical system, each troubleshooting. Such as the temperature rose very slowly, we must view the air circulation system, look at the wind circulation damper is open properly, otherwise, check the air circulation motor is functioning properly. Such as temperature overshoot badly then you need to set the parameters of PID tuning. If the temperature rise directly, over temperature protection, then the controller failures, to be replaced control instrument.
(2) during the operation of the test equipment suddenly fails, control instruments corresponding fault appears on the display prompts and a voice alarm. The operator can control the operation of the device using the troubleshooting chapter quickly check out which category failure, you can ask professionals quick troubleshooting to ensure that the test correctly. Other environmental test equipment in use there will be other phenomena, it should be specific phenomenon, specific analysis and troubleshooting.
3 reach the test temperature indicator, then you have to observe the temperature changes, the temperature drop is very slow, the temperature to a certain value, or the temperature tends to increase, the former is necessary to check the laboratory vacuum furnace to make low-temperature test whether the studio before drying, so the studio remain dry and then do the test sample into the working chamber test, the working chamber of the test sample is placed too much, so that indoor air can not fully cycle, the exclusion of the above reasons , it is necessary to consider whether the failure of the refrigeration system, and so we must ask the manufacturer's maintenance professionals.

 

Through type muffle furnace, gas carburizing furnace heat treatment work safety rules

1. Blast furnace gas pipes should be checked to open the valve sealing and gas pipeline pressure is not less than the specified value.2. Air furnace test putter agencies, institutions and rod lifting mechanism work.3. Release of the compression spring to a predetermined size range.4. Regulate the water level in the water seal, seal exhaust combustion tube through the open valve, close the valve through the seal.5. The feed side of the oven door closed, turn on the discharge side of the door look, when kerosene spray mist flow direction normal form and then close the door.6. The feed chamber burner lit.7. Exhaust valve seal shall be discharged by the barrier.8. First, the intermittent production carburizing furnace tank.9. Parts placement, parts and not less than 5 mm distance between the parts; Part bottom edge does not exceed the specified length and height.10. To quickly switch the feed and discharge gate door, but the speed of push-pull rod to be stable.11. Parts should be located in a pre-cooling chamber is below the thermocouple.12. Furnace filled with 24 chassis only allowed to continue feeding must first pull push.13. When we shutdown the furnace zone down to the same temperature, and then began to naturally cool.14. Equipment cleaning:(A) in the continuous production carburizing furnace tank cleaned once a week, intermittent production furnace tank cleaning should be carried out immediately after shutdown,(2) tank cleaning oven temperature is 850 ~ 870 ℃ when the chassis all out;(3) a nozzle with compressed air blown from the feed end of the furnace, the valve opening was not too much, blowing must move around, to prevent local overheating;(4) In the carburizing gas burner with kerosene before cleaning.15. Chassis or fixture should return after quenching chilling room to remove oil.16. Found that the exhaust pipe blockage (sudden increase in pressure inside the furnace) should be cleaned up immediately. First open the exhaust valve seal barrier, and then close the valve exhaust pipe through the water seal. Cleared should hit the exhaust pipe valve seal the opening, and then close the barrier seal exhaust valves.17. Note:(A) combustion conditions and constant attention to districts gas pressure;(2) Open the door can not stand them, to prevent the flame jet burns;(3) Note whether the combustion burner into sections and wedge the door with torches check for leaks;(4) found in the work burner flame goes out, you should immediately turn off the gas valve, close the air valve;(5) working parts from falling or wedge the door switch not working, you should stop feeding, remove the parts.

 

Tube furnace fire accident occurred when oil disposal measures

1, the first self-adjusting valve from the gas bypass valve at the gas cut off, lower the fire, when off the gas slowly to prevent tempering explosion.
2, a heat exchanger from the rich oil-rich oil outlet valve is closed into a tube furnace at the oil-rich, to prevent leakage of oil-rich continue to make fire intensified. De-oil rich in benzene column close the valve at the inlet tube furnace oil-rich tubular pipes, the pipe and other pipe furnace off.
3, surrounded by oil spillages with sand to prevent the spread of fire.
4, if the fire is not possible to place the furnace fire steam, the muffle furnace steam valve to open hearth fire put out the fire.
5, from the door of the joints foam firehouse with fire hoses connected to the foam bubbles firehouse. Tube furnace with foam fire on parts of the fire.
6, the most critical to control the outflow of gas and oil-rich, to prevent the fire intensified.

 

What laboratory furnace masonry carried

Laboratory furnace, furnace masonry and methods of the basic sequence of what? Laboratory furnace method of wet masonry masonry and dry assemble two kinds: Wet puzzle parts: the Ministry of flames melted the side walls and arch roof space, flue, chimney and furnace insulation bricks, masonry used in the wet mud bricks used should be based on refractory clay material prepared accordingly.
① laboratory furnace bottom masonry, including the passage at the end. Qi Hao large brick insulation brick and kaolin after the masonry wall at the inside and outside to relax 30-50mm leveling. Multilayer structure underground masonry elevation negative deviation must be controlled, the bottom of the total thickness tolerances generally-3mm. In the bottom layer of kaolin large brick laying above chrome ramming as a sealing layer to prevent liquid penetration to the corrosion resistance of glass poor clay layer.
② In the bottom steel structure on the basis of acceptance, according to the baseline and experimental furnace construction furnace, furnace centerline release related to feeding port, front and rear bubbling and forming pathway of Taiwan brushed drain board centerline.
③ lifting column. Interim measures to stabilize the column, and then install the ballast ballast according to design requirements angles, columns and ballast ballast angle must be close to the same time determined the exact elevation.
④ masonry wall, including the passage wall. The bottom brick masonry wall must ensure that the level of degree, or to the bottom of the tile area for processing until it reaches the requirements. Multi-wall brick building, the first in the field after the operation to make sure the furnace size, non-timber hewn side facing brick hearth. Masonry joints to be staggered corner pressure, strictly maintain verticality.
⑤ masonry parapet, the front wall, back wall and channel flame space. Masonry parapet bracket should be carefully examined, pallets and bearers installed after passing. Masonry brick and chest wall hooks have taken measures to prevent the dumping of the kiln.
⑥ big arch masonry. Production arch tires, do carry through gantry sedimentation test and check the corresponding size, the big arch masonry to the center from both sides simultaneously, and requires continuous operation, try to control! * + Complete. Large arch insulation layer construction after the end of the kiln to be baked.
⑦ laboratory furnace masonry flue, chimney. Kiln debris must be cleared, and with a vacuum cleaner after masonry. Laboratory furnace, furnace flue and chimney masonry, but also compatible with the metal heat exchanger, access paths masonry chimney must be completed before other masonry.