The rapid increase in cutting speed has caused doubts about the effect of cutting fluids. Especially after the use of new tool materials such as cemented carbide, ceramics, CBN, the life of the tool has been greatly improved; at the same time, the cutting fluid pair The environment and the operator are harmful. In the metal processing of car, milling, drilling, grinding, etc., due to the use of metal cutting fluid, a large amount of oil mist particles are formed in the air. This phenomenon has caused widespread concern about air quality problems in workers' breathing areas. Because long-term exposure to this oil mist is very unfavorable to workers' health, according to the National Institute of Occupational Safety and Health (NIOSH), there are as many as 1.2 million workers exposed to metal cutting fluid oil mist every year. Therefore, the study of metal cutting fluid oil mist is a significant topic.
1. Formation of oil mist in metal cutting fluid 1.1 Mechanism of oil mist In order to effectively lubricate, cool and clean, the metal cutting fluid undergoes pumping, spraying and high-speed rotation of the tool or workpiece during the use process. Evaporation and other processes, which determine the cause of the oil mist is very complicated, mechanical, physical and chemical factors intertwined and work together. However, not all factors have a decisive influence on the generation of oil mist. The formation of oil mist in metal cutting fluid during processing can be mainly attributed to two mechanisms, atomization and evaporation: atomization is the conversion of mechanical energy into surface energy of droplets. The process is mainly caused by the intense impact of the liquid on the fixed and rotating unit in the machine tool system, which is broken up to form small droplets floating in the working environment; the evaporation occurs due to the large amount of heat generated in the cutting zone, which is passed through the cutting The liquid causes its temperature to be significantly higher than the saturation temperature, and boiling occurs on the solid-liquid contact surface to generate steam. These vapors then condense with small droplets or other particles in the surrounding air to form an oil mist.
1.2 The existence of oil mist The metal cutting process can produce the following three types of oil mist:
(1) A clean oil mist generated by jet impact, free of solid dust;
(2) Smoke generated by evaporation or burning due to high temperature of heating or high-speed cutting;
(3) Oil mist containing grinding dust generated by metal cutting fluid jetting during grinding. Oil mist is produced in different ways, and its particle diameter range is also quite different. Under normal circumstances, the oil mist generated by the mechanical atomization process mainly exists in the form of droplets, and the diameter of the droplets is wide, usually 2 to 10 um. The oil vapor generated by evaporation also forms a very small diameter condensate suspension during the condensation process, and the particle size is usually less than 2 um. Medical research has shown that oil vapors and large particle droplets are relatively less harmful to human lungs. Oil mist in the form of oil vapor is inhaled into the lungs and exhaled. They are not captured by the alveoli, and large droplets of oil cannot enter the lungs through the nose and bronchi. Only in the form of droplets, oil mist particles with a diameter of less than 5um can reach the alveoli smoothly and precipitate in the lungs, thus causing greater harm to the human body.
2. Control of oil mist in metal cutting fluid 2.1 Traditional method The concentration of oil mist particles in the atmosphere of the control workshop mainly includes mechanical and chemical methods. Mechanical methods include the installation of exhaust fans, oil mist traps, and the installation of guards or splash guards around the machine. These methods are easy to implement and have obvious effects, so they are widely used. But these methods have their own shortcomings. Although the exhaust fan is simple and effective, a simple exhaust device is not desirable. It merely moves a large amount of oil mist from the indoor to the outside, which is an extremely irresponsible behavior to the environment. It is reliable to install an oil mist collector or an oil mist separator in the workshop to purify or recycle the oil mist-containing gas.
2.2 Centrifugal (simple maintenance, economical and practical) Recommended products: Oil mist filter HJD series oil mist filter application of precision filtration and centrifugal separation technology, the filtration effect of the mist is up to 99.8%, the scope of application is wide, can It is an aqueous or oily mist.
HJD oil mist filter works:
A. The inhaled mist and dust enter the oil mist filter and first collide with the inertial collision plate, and then the large particle mist is removed by a secondary filter.
B. The granules are coarsely granulated under the action of the impeller to improve the filtration effect of the next filter.
C, three filters are high-efficiency filters, which can filter out fine oil mist.
Features:
High smoke collection efficiency, oil mist filter for mist-like dust collection efficiency of up to 99.8%
Easy to maintain, plug-in installation.
The equipment operates at low noise, less than 68dB (A).
The operation is safe and reliable, and there is a phase loss and overheat protection function. The device has no exposed power and the operation is safe.
The oil mist filter has a wide range of applications and is suitable for the purification of various water-soluble and oily mists.
2.3 Electronic (no consumables) Recommended products: oil mist cleaner (ion ion)
The working principle of the HJP oil mist cleaner is to ionize the air by means of corona discharge, so that the oil smoke particles in the air are charged, and the charged particles move to the discharge electrode under the action of the electric field force through the electric field, and accumulate after discharge. It is thus recycled (the recovered oil mist can be reused for the factory to reduce the economic cost of the coolant), while the discharge is clean air.
The oil mist cleaner includes four parts: the induced wind farm, the electrical control and the oil collection area. The soot and oil mist enter the electric field under the guidance of the negative pressure of the induced draft fan, firstly ionized by the electric field and charged (this process is called “chargedâ€), and the charged ions are trapped under the action of the electric field (this process is called "Dust collection"), the charged particles release the charge on the dust collecting electrode and collect the oil droplets and finally return to the oil collection area for recovery.
The oil mist cleaner can purify and collect various kinds of smoke, including acid gas and alkaline gas. The collection efficiency is more than 99% and the minimum filtration precision is 0.01UM. It is an ideal equipment for metal processing industry and clean production in the machining industry.
Features:
Efficiency and energy saving, oil mist recovery efficiency is greater than 99%.
Improve the working environment and achieve cleaner production.
Protect the physical and mental health of employees and reduce the incidence of occupational diseases.
Reduce the impact of smoke and oil mist on the machine system and control system, and reduce the maintenance cost of the machine.
The oil mist cleaner can recycle the part of the cooling oil that generates smoke from the machine tool, reducing production costs.
The function and application of the oil mist collector:
Reduce the impact on employees:
Oil mist particles of 0.3~3.5UM will remain in the human body, posing a health hazard.
Reduce work accidents:
Oil mist deposition makes the work area, floor and walkway slippery, which is easy to cause wrestling accidents.
Reduce fire hazards:
Oil deposits form potential fire hazards on walls, ceilings, and equipment.
Reduce coolant consumption:
The recovered oil mist can be reused as an economic expense for the plant to reduce coolant.
Application range:
It can be used for oil mist and water mist generated during processing of cutting oil, diesel and synthetic coolant.
Application example:
CNC lathes, washing machines, external circles, surface grinders, hobbing, milling machines and gear shaping machines, vacuum pumps, spray test chambers, EDM, CNC machining centers.
Selection instructions:
Closed cavity: inner cavity volume (M3) coefficient (1/min) air volume (M3/min) [length * width * height] * function coefficient = required air volume.
Example: CNC lathe, inner cavity size 1.1m width 1.05m height 1m[1.1*1.05*1]*4=4.6 M3/min
According to the above formula, it is most suitable to calculate the air volume using HJD-400.
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