Vacuum sintering furnace: 十月 2016

2016年10月31日星期一

What is the importance of vacuum sintering furnace cooling system?

Vacuum sintering furnace is electric heating element near the vacuum heating furnace. Vacuum furnace cooling system is an important part of vacuum furnace. Cooling water should maintain smooth, otherwise the temperature rise caused downtime. This is vacuum furnace work often neglected problems When no one management major damage may result in vacuum furnace.
Molybdenum vacuum furnace heating after long time use will harden, shrinkage, drop, lodging first lap, after fusing (melting) wait for a phenomenon. To make the vacuum furnace heating wire is necessary strength at high temperature, prevent hardening, collapsed or droop, first to design the structure of the vacuum furnace heating wire size, such as spiral wire, pay attention to the heating element bending diameter, pitch and screw pitch diameter, etc. The heating body is going to loose by vacuum furnace insulation lining, 95 ceramic on insulation lining is put aside, leave the expansion space. Shelve location should be suitable for, one is in commonly 100 ~ 100 mm, and can prevent resistance wire to lie prone on strong hook. Also should avoid furnace silk direct contact between each other (short circuit), usually to pad spacer.
Deal with cooling water with biological decomposition chemical auxiliary method, the purpose is to keep the minerals in suspended state, reduce the rubber tube, coil and water jacket in sediment accumulation, to make the water clear. This generally adopts an automatic device to complete, it can monitor the conductivity of the water, automatically added chemicals, wash water, add fresh water. Cooperate with auxiliary steam filtration system, this method can guarantee the pH of the water control, to prevent redundant mineral deposits in the cooling water system. After the system work stable, at least once a month for the water quality test case after processing or owed.
Vacuum tempering furnace shell and the heat exchange equipment material test sample should also be placed in water system, a yearly weight loss test to check the effect of the processing. Coil of diffusion pump cooler must pay special attention to. Should be check regularly. If blocked, diffusion pump will be overheating and loss of function, but also further cause the diffusion pump heater burning, cause of expensive, time-consuming repairs. When snake-like cooling water pipe plug, water will disconnect with water and the drainage and use compressed air to blow or wash with dilute acetic acid solution.

2016年10月26日星期三

What are the factors affecting the quality of vacuum sintering furnace production?

Vacuum sintering furnace production quality besides internal factors and there are many external factors, we take a look at what are the factors that affect the quality of vacuum furnace production.
Structure, temperature control of vacuum sintering furnace, heating process and furnace atmosphere etc., will directly affect the quality of the products after vacuum furnace production. Within the forging heating furnace, raise the temperature of metal, can reduce the melting resistance, but the temperature is too high will cause grain oxide or burnt, seriously affect the quality of the product in a vacuum furnace. In the process of heat treatment, if the steel is heated to above the critical temperature of a point, and then suddenly use cooling cooling, can improve the hardness and strength of steel; If heated to a temperature below the critical temperature at some point after slow cooling, the more resilient and make steel.
So if in order to obtain a more precise size of the workpiece and the surface is bright and clean, can adopt the way of no oxidation furnace for production, control of the oxidation burning loss of vacuum furnace is the key.

2016年10月23日星期日

Vacuum sintering furnace is how to work?

Vacuum sintering furnace is in a vacuum environment to be heated objects in protective sintering furnace, its heating mode is more, such as resistance heating, induction heating, microwave heating, etc. Vacuum induction furnace is heated objects to make use of induction heating protective sintering furnace, can be divided into the power frequency, medium frequency, high-frequency, such as type, can be ascribed to a subclass of vacuum sintering furnace.
Vacuum sintering furnace can meet the requirements of rapid heating process; Intelligent temperature control switches use imported more sections program c the instrument control, c the stability of the control switches, repeatability is very reliable; Frequency conversion stepless speed regulation, stainless steel mesh belt transmission, the appearance of the new design concept, to ensure that the product smooth conveying.
Vacuum sintering furnace by using the principle of intermediate frequency induction heating, the high temperature of tungsten crucible in the winding, by heat conduction to work on, suitable for scientific research, military units for hard metal such as tungsten, molybdenum and its alloy powder sintering molding.

2016年10月19日星期三

In the vacuum furnace temperature distribution

Graphite rod arrangement method on either side of the heating element is decorated in the heating chamber, especially suitable for high vacuum furnace. In a high vacuum atmosphere, thermal radiation produced by on both sides of the heating element area artifacts can be uniformly heated. When the temperature at 400-1300 ℃, heating area each point temperature difference of + / - 5 K. In the '60 s, before the temperature control has been one of the main problems in the heat treatment technology. Because later adopted the technology of electronic temperature control, this problem has been resolved. At present, from the point of view of the temperature distribution, the precision of the hotspot temperature distribution is an important problem.
We almost always preferred to obtain uniform temperature on the structure can guarantee the hotspots, as for temporarily due to some reason make the hotspot temperature uneven phenomenon will disappear with the extension of heat preservation time. On the other hand, the temperature is higher or lower hotspot makes it consistently throughout the harmful effects of heat treatment. Below we present in this fruitful, the temperature gradient is lower than 0.01 K/cm vacuum furnace structure. In addition to the vacuum furnace temperature uniformity, there are some other advantages. Consume less power, completely avoid the use of toxic materials, heating, smoke pollution to the environment to produce outgassing, perfectly solve the problem of the material surface oxidation or distortion. Because of these advantages have now made vacuum furnace heat treatment process of necessary conditions. Heat transfer in a vacuum From the point of heat transfer, vacuum play a dual role.

2016年10月17日星期一

On analysis of nitrogen and oxygen mixed sintering furnace

Chain belt type sintering furnace atmosphere, Cu and O in the appropriate temperature and oxygen content of appropriate conditions the following chemical reaction: Cu + O2 - Cu2O, it has completed the preoxidation of Cu, but actually the suitable oxygen content in the process and the suitable temperature is very important, for this point, the device is equipped with two nitrogen oxygen mass flowmeter with high resolution, the two mass flowmeter in the mixed box respectively on the two interfaces of (mixed box: oxidation of nitrogen and oxygen mixed device), at the same time, each into the chamber of a stove or furnace temperature regions merged with mixed gas box connected to another interface.
Nitrogen oxygen after mixed, each node into the chamber of a stove or furnace, high-precision mass flowmeter guarantees the oxygen content in the hearth can be regulatory. Cu and O2 reaction in suitable conditions, the formation of Cu in Cu2O eutectic phase, it laid a solid foundation for high temperature sintering of DBC.
Chamber of a stove or furnace in actual temperature differ with performance temperature around 10 ℃, the real temperature of the furnace in the platform of high temperature of 1079 ~ 1081 ℃, should be about 12.5 min, under the condition of such process curve, substrate adhesion is good, the test strip adhesion test is within the scope of the requirements (copper and Al2O3 substrate adhesion greater than 60 n/cm, pulling speed of 50 mm/min).
After copper and Al2O3 substrate single adherent, there will be a curved surface radian, this is due to the different expansion coefficient of the Cu and Al2O3. When a second surface adhesion, can eliminate the bending caused by the different expansion coefficient, the surface is very smooth. Between copper and ceramic substrates without any air bubbles.

2016年10月13日星期四

The five requirements of vacuum sintering furnace

In order to guarantee the billet in the sintering process of powder forming dewaxing (lubricant or forming agent), reduction, sintering, alloying and densification, the need when sintering on the sintering temperature, protective atmosphere, ware transmission speed, heating and cooling speed and so on carries on the adjustment and control. Sintering furnace on the structure and function, therefore, should meet the following five requirements:
1. L have perfect dewaxing unit or dewaxing.
2. Has the air tightness, can isolate air outside the furnace and ensure smooth protective atmosphere in the furnace.
3. The temperature control of the paragraphs, paragraphs atmosphere is adjustable;
4. Continuous sintering furnace, with conveyer and the transmission speed is adjustable;
5. With fast cooling device, can be sintered parts rapid cooling to the temperature can be released.
The above is the five requirements, vacuum sintering furnace sintering furnace for sintering of powder metallurgy products of special equipment, its variety, reasonable selection and correct use of sintering furnace to ensure the quality of the powder metallurgy parts.

2016年10月11日星期二

Vacuum sintering furnace safety operation procedures

Vacuum sintering furnace is heated objects to make use of induction heating protective sintering furnace, can be divided into the power frequency, medium frequency, high-frequency, such as type, can be ascribed to a subclass of vacuum sintering furnace. Vacuum induction furnace is under vacuum or protective atmosphere conditions, using the principle of intermediate frequency induction heating make hard alloy tool bit and all kinds of metal powder compacting sintering of complete sets of equipment, is for hard alloy, metal dysprosium, designed in the industrial production of ceramic materials.
Vacuum sintering furnace safety operation procedures
1. Medium frequency induction coil, power supply, vacuum furnace, cooling water, the water of reservoir must be filled with water can not have impurities.
2. To start the pump, that its frequency power, vacuum induction coil, furnace, furnace cooling water circulation system is normal, and adjust the water pressure control in the specified value.
3. Check the vacuum pump power supply system, the pulley belt tightness, vacuum pump oil is located in the oil seal observation hole centerline. Check completed after artificial turn the vacuum pump pulley, without exception, but in the case of closing butterfly valve, vacuum pump.
Within 4. Check the vacuum furnace, vacuum furnace in the level of health, good insulation, induction coil, vacuum sealing tape elastic, qualified size.
5. Check the lever handle to start the vacuum furnace is flexible.
6. Check the rotation type McLeod gauge whether accord with requirement.
7. Check the graphite crucible, furnace charging accessories are complete.
8. After more than ready, connected to the power supply, intermediate frequency power supply switch, started in the intermediate frequency rules, try to start the inverter, success after the stop frequency, before blowing in.
9. Observation, the thermometer hole of the vacuum furnace cover, each furnace must be clean processing, in order to observe and temperature measurement.
10. According to different sintering furnace charging products, adopt corresponding furnace charging mode. According to relevant material plate furnace charging rules, do not get optional change.
11. In order to maintain constant temperature, prevent heat, hot pot and add carbon fiber on the second floor, cover on heat insulation screen again.
12. Good vacuum sealing tape.
13. The operating lever handle, turn the vacuum furnace top cover closely coincide with furnace body, put down the lid, and fixed lock nut.
14. Slowly open the butterfly valve, smoked furnace, air and vacuum degree reach the specified value.
15. After vacuum to specified requirements, to start frequency, adjustment of intermediate frequency power, as stipulated in the relevant material of sintering operation; Heating, heat preservation cooling.
16. After sintering, the stop frequency, the stop frequency conversion switch, inverter stop working, and disconnect the medium frequency power supply points total brake brake and power off.
17. After observed from furnace furnace black hole observation, turn off and disconnect current vacuum pump, vacuum butterfly valve and tap water to cooling and induction coil, furnace, finally stop the pump.
18, intermediate frequency voltage 750 v electric shock risk. In the whole operation and inspection process, must pay attention to the safety operation, do not contact with the hand intermediate frequency electric cabinet.
19. In the process of sintering, induction coil, at any time from the furnace side hole to observe whether put arc phenomenon, if discovery is unusual phenomenon, should immediately report relevant personnel processing.
20. Start the vacuum butterfly valve should be slow, otherwise you will take oil by extraction, rapid, adverse consequences.
21. The correct use of rotary McLeod gauge, otherwise it will cause the vacuum reading error or mercury resulting from operation, rapid overflow caused by public nuisance.
22. Pay attention to the safe operation of the vacuum pump pulley.
23. In the vacuum sealing tape, cover furnace roof, pay attention to prevent pressure hand.
24. All that under the condition of vacuum, volatile affect vacuum health, pipes get clogged, or vacuum pump caused by dirty workpiece or container, not charging.
25. All products with forming agent (such as oil or paraffin, must take off before charging sintering, otherwise it will cause adverse consequences.
26. The whole sintering process, must pay attention to the water meter pressure range and cooling water circulation, so as to avoid an accident.

2016年10月8日星期六

Understand the high requirements of the high temperature vacuum furnace

High temperature vacuum furnace ironmaking automation is designed to make production process optimization, produce stable quality products and improve the process operator working conditions, this requires the technical and economic aspects of productive rationalization measures, in the process of ore smelting discount, physical and chemical changes very difficult to control thedifficult measurement.
More and more high mechanization degree of high temperature vacuum furnace, vacuum environment was does not have other forms of sintering (when the furnace vacuum degree is 1.3 * 10-1 PASCAL, remaining in the furnace gas purity argon 99.99987%); Vacuum sintering can make material before a liquid particle oxidation film completely ruled out, so as to change a good wettability of the liquid with carbide phase, to improve the alloy organization structure, improve the performance of alloy. Due to the vacuum press billet pore reduced the amount of gas in steel rolling workshop push by the steel type heating furnace of continuous development to all kinds of stepping type furnace, roller hearth furnace, furnace, chain furnace, etc.
Some within the chamber furnace heating shaped blank in the past, now change in annular furnace heating, productivity had the very big enhancement. The use of the electronic computer, the stove from loading assumed, paragraphs in the furnace temperature control, fuel and air traffic control, automatic control, furnace pressure until the steel material on time and discharging program operation, are given by computer control values, and be able to adopt the optimal control of the furnace condition, on the temperature of the steel material and the temperature difference at very accurately.

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