Grinding is the final process of bearing machining, which has a direct impact on the accuracy, performance and service life of the finished bearing. During the machining process, the coolant prevents burns on the workpiece, improves the surface precision and roughness of the workpiece, and improves the resistance of the workpiece and the machine tool. The ability to rust and extend the life of tools and machine tools plays a very important role. Therefore, the proper use and maintenance of the grinding fluid is essential in the bearing processing.
1. The role of cutting fluid
Wet processing in the bearing processing process can greatly improve the cutting ability and service life of the tool, improve product accuracy and reduce scrap rate. The main advantage of wet machining using cutting fluid is
1) Lubrication: The cutting fluid can lubricate the tool and improve the cutting ability of the tool;
2) Cooling effect: The cutting fluid with a certain flow rate can cut the cutting tropical, thus reducing the temperature of the cutting tool;
3) Chip action: The chip liquid can wash away the chips and fall into the chip drains. At the same time, the chips in the grooves can also use the cutting fluid to achieve hydraulic chip removal.
4) Improve the surface roughness of the workpiece: the cutting fluid washes away the iron scraps on the machined surface, and the iron scraps do not scratch the machined surface, thereby improving the roughness;
5) Reduce rust: Select appropriate cutting fluid to prevent corrosion of workpieces and machine tool guides;
2. Reasonable use of cutting fluid
The cutting fluid can be roughly divided into oil-based cutting fluid and water-based cutting fluid according to the composition. The oil-based cutting fluid, such as the cutting fluid used in the super-finishing of the bearing factory, is a kerosene-based cutting fluid with a small amount of mechanical oil. After the oil-based cutting fluid passes through the processing part, it generally contains only solid impurities such as abrasive grains and chips, and in practice, only the solid impurities need to be separated to obtain a clean cutting fluid, so the treatment is relatively simple. The other type is a water-based cutting fluid, represented by an emulsion, in which fine oil droplets are highly dispersed in water, and the emulsion also contains various surfactants and rust inhibitors. After the emulsion passes through the processing site, it can easily breed microorganisms in addition to solid impurities such as abrasive grains and chips. Microorganisms include bacteria, molds, fungi, etc. These are the main factors affecting the quality of the emulsion. The normal emulsion contains no more than 1000 mg/mg. When the bacteria content reaches 10,000-100,000/mg, the emulsion is It will become black and smelly, the cooling and lubricating effect will drop rapidly, the unpleasant smell will be emitted, the equipment will be corroded, and even the bacteria will block the filter. At this time, all the emulsion must be replaced and the circulation system must be thoroughly cleaned.
3. Mechanism of bacterial growth in cutting fluid
Bacteria in the emulsion can be divided into two types: aerobic bacteria and anaerobic bacteria. Among them, anaerobic bacteria are the main culprit in causing black odor of emulsion. The emulsion always contains a certain amount of insoluble oxygen. Therefore, there are always anaerobic bacteria that grow and grow in this environment, and consume the insoluble oxygen in the emulsion, causing the water body to be deprived of oxygen. At this time, the anaerobic bacteria will take the opportunity to reproduce. Hyperplasia, anaerobic bacteria use the organic components and salts in the emulsion as nutrients, and at the same time decompose out the pungent gas such as ammonia and hydrogen sulfide. The organic acid decomposed by the anaerobic bacteria causes the pH of the emulsion to decrease and The iron reaction makes the emulsion appear grayish black. This process is carried out quite quickly in a certain temperature and a certain amount of "dead water" environment. The purpose of the emulsion treatment system is to try to delay the process.
4. Use and maintenance of cutting fluid
4.1 Configuration (Dilution) The configuration of the cutting fluid is diluted with water in a certain proportion. Water-based cutting fluids, especially emulsions, should be noted when diluting:
1) Water quality Under normal circumstances, it is not advisable to use water exceeding the recommended hardness, because the calcium and magnesium ions contained in the high hardness water will invalidate the anionic surfactant, the emulsion will decompose, and the water-insoluble metal soap will appear. Even if the emulsion is made of a nonionic surfactant, a large amount of metal ions can cause the micelles to aggregate, thereby affecting the stability of the emulsion. Too soft water is also not suitable for use. Emulsions formulated with too soft water tend to produce a large amount of foam during use.
2) The dilution of the dilute cutting fluid is related to the stability of the emulsion. Before using the cutting fluid, determine the dilution ratio and the volume of the required emulsion, and then calculate the amount of the cutting fluid used and the amount of water. When diluting, select a clean container, pour all the required water into the container, and then add the original solution under low-speed agitation. When the configuration is started, the addition rate of the original solution is based on the absence of the unemulsified stock solution. Note that the procedure for adding stock solution and water cannot be reversed.
4.2 Maintenance
Extending the service life of the emulsion In addition to the selection of the proper quality and proper use of the coolant, the maintenance of the cutting fluid is also a very important factor. The maintenance work of cutting fluid mainly includes the following items:
(1) Ensure the smooth flow of the liquid circulation line and eliminate the metal chips, metal powder, mold mucus, decomposition products of the cutting fluid itself, grinding wheel ash, etc. of the circulating line in time to avoid clogging.
(2) Antibacterial cutting fluid (especially emulsion) is essential for bacteriostatic growth. During the use of cutting fluid, the bacterial content should be checked regularly and appropriate measures should be taken in time.
(3) Purification should remove the chips and floating oil in the cutting fluid in time to eliminate the bacterial breeding environment.
(4) Check the PH value of the cutting fluid regularly, and make a big change, and take corresponding measures in time.
(5) Adding cutting fluid in time, because the cutting fluid is continuously consumed due to splashing, atomization, evaporation and carrying of materials and chips during recycling, it is necessary to add new liquid in time to meet the total circulating fluid of the system. constant.
5. Purification of cutting fluid
The filtration and purification of the cutting fluid is the process of removing a certain proportion of the relatively large solid particles in the cutting fluid from the cutting fluid. The filtered and purified cutting fluid can be reused in mechanical processing for recycling purposes. The advantages of filtration and purification of cutting fluid are mainly reflected in the following aspects:
1) Extend the cutting fluid replacement cycle: According to the practice of our factory, the replacement cycle of the cutting fluid after filtration can be greatly lengthened.
2) Improve the service life of tools and grinding wheels: In recent years, studies have shown that if the impurities (such as debris, grinding wheel powder, etc.) in the cutting fluid are reduced from 40μm to less than 10μm, the life of the tool (or grinding wheel) can be extended by 1- 3 times.
3) Improve the surface roughness of the workpiece and reduce the scrap rate.
4) Extend the service life of the pipeline and pump set, and the solid particles such as cutting fluid in the cutting fluid will accelerate the wear of the pipeline and pump components.
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A band-pass filter or bandpass filter (BPF) is a device that passes frequencies within a certain range and rejects (attenuates) frequencies outside that range.
Bandpass filters are widely used in wireless transmitters and receivers. The main function of such a filter in a transmitter is to limit the bandwidth of the output signal to the band allocated for the transmission. This prevents the transmitter from interfering with other stations. In a receiver, a bandpass filter allows signals within a selected range of frequencies to be heard or decoded, while preventing signals at unwanted frequencies from getting through. Signals at frequencies outside the band which the receiver is tuned at, can either saturate or damage the receiver. Additionally they can create unwanted mixing products that fall in band and interfere with the signal of interest. Wideband receivers are particularly susceptible to such interference.[3] A bandpass filter also optimizes the signal-to-noise ratio and sensitivity of a receiver.
In both transmitting and receiving applications, well-designed bandpass filters, having the optimum bandwidth for the mode and speed of communication being used, maximize the number of signal transmitters that can exist in a system, while minimizing the interference or competition among signals.
Outside of electronics and signal processing, one example of the use of band-pass filters is in the atmospheric sciences. It is common to band-pass filter recent meteorological data with a period range of, for example, 3 to 10 days, so that only cyclones remain as fluctuations in the data fields.
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