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Working principle of slow wire processing

 Slow wire walking, also called low-speed wire walking, is a kind of CNC machining machine tool that uses continuously moving fine metal wire as an electrode to pulse spark discharge on the workpiece to generate a high temperature of over 6000 degrees, ablate metal and cut into a workpiece. The principle of wire processing is the phenomenon that there is a gap between the wire electrode and the workpiece, and the metal is removed by continuous discharge. Since the slow-moving wire cutting machine adopts the method of wire electrode continuous feeding, that is, the wire electrode is processed during the movement, so even if the wire electrode is worn out, it can be continuously supplemented, so it can improve the machining accuracy of the parts and slow the wire. The surface roughness of the workpiece processed by the cutting machine can usually reach Ra=0.8μm and above, and the roundness error, linear error and dimensional error of the slow-moving wire cutting machine are much better t

Classification of CNC Machining Occupation Levels

1. Blue-collar layer:   That is, CNC machining operation technicians, proficient in machining and CNC machining process knowledge, proficient in the operation and manual programming of CNC machine tools (attributes: automated machine tools), understand automatic programming and simple maintenance of CNC machine tools (attributes: automated machine tools), such There is a large market demand for personnel, and they are suitable for operating workers of CNC machine tools (attributes: automated machine tools) in the workshop, but due to their single knowledge, their wages will not be much higher.   2. Gray collar layer:   One, CNC machining programmer:   Master the knowledge of 5 Axis CNC machining Aluminum   technology and the operation of CNC machine tools (attributes: automated machine tools), be familiar with the design and manufacturing expertise of complex molds (title: mother of industry), and be proficient in 3D CAD/CAM software, such as UG, GOOGLE PRO/E, etc. ; Familiar with CNC

Hydrostatic guideway of CNC machining lathe

The static pressure slide rail (TTW guide) of the CNC machining lathe transfers the oil with a certain pressure through the throttle to the oil cavity between the sliding surfaces of the slide rail (TTW guide) to form a pressure oil film to float the moving parts , Make the sliding rail (TTW guide) surface in a pure liquid friction state.   CNC machining General CNC machining usually refers to computer digital control precision machining, CNC machining lathe, CNC machining milling machine, CNC machining c17200   beryllium   copper   and milling machine, etc. The feed route of finishing is basically carried out along the part contour sequence. Therefore, the focus of determining the feed route is to determine the feed route of rough machining and idle stroke. In the numerical control processing, the control system issues instructions to make the tool perform various motions that meet the requirements, and the shape and size of the workpiece are expressed in the form of numbers and lette

National IV vehicle owners need to pay attention to how urea is used in vehicles

As a high-frequency vocabulary after the implementation of the National IV, the car urea solution began to rise in popularity at the beginning of the year. Many card friends ask, can the urea used in vehicles be replaced by agricultural urea and purified water? The answer is no substitute. Urea for vehicles can only purchase urea solutions that meet the corresponding standards on the market.
Urea for vehicles cannot be replaced by agricultural urea or purified water
●Agricultural urea is prone to poisoning of the catalytic converter. It cannot replace the urea solution for vehicles. It is a urea solution with stable concentration (consisting of 32.5% high purity urea and 67.5% deionized water), which is used to reduce the nitrogen oxides in the exhaust gas after the combustion of automobiles.
Ordinary fertilizer urea contains biuret, mechanical impurities, formaldehyde, and metal ions, which can poison the catalyst of the SCR exhaust gas post processor and cause damage to the components. Moreover, we searched the Internet and found that the value of the urea pump is less than 10,000 yuan. If there is irreparable damage, it will be a big loss for the user.
In addition, because fertilizer urea is easy to crystallize at low temperature and the concentration of urea solution cannot be guaranteed, the conversion rate of nitrogen oxides will be low. In addition, the loss of ammonia gas will destroy the SCR system, making the vehicle unable to meet the emission standards.
●Adding water to replace urea is very polluting to the environment-a common practice to resist National IV cheating is to bypass OBD monitoring and replace the urea solution with water to ensure that the engine works normally. Because the engine of the National Fourth SCR route is fully burned, the NOx content of the emission is relatively high.
Urea for vehicles cannot be replaced with agricultural urea and purified water. The behavior of adding water to replace urea should be denied and resisted. Nitric acid produced by the combination of NOx and water in the air is a major cause of acid rain. At the same time, NOx and other pollutants will produce photochemical smog pollution under the action of ultraviolet rays. It is very harmful to the atmosphere and has a great impact on human health. Therefore, the act of adding water to replace urea should be denied and resisted.
●Vehicle urea selection. There are many other names for vehicle urea solution in China. According to the European name, it is called “Adblue” solution. In North America, it is also called DEF diesel emission treatment fluid. It is also called diesel engine nitrogen oxide reducing agent in China. Denitrification agent for vehicles.
Most diesel vehicle manufacturers tend to use a 32.5% urea aqueous solution (AUS32) as a reducing agent. The concentration of urea directly affects the reduction rate of nitrogen oxides and the crystallization point of the urea solution. Too high or too low concentration not only can not improve the conversion efficiency of nitrogen oxides, but will cause the residual ammonia to form secondary pollution. The 32.5% concentration is chosen because the crystallization point of the vehicle urea solution at this concentration is *low (freezing point -11°C).
●Attention should be paid to the details-the urea solution must be filled with impurities and overflow. During the filling process, it is necessary to avoid impurities entering the solution and the urea tank as much as possible. Generally, urea solution has a special tube when filling, just open the mouth of the urea tank and insert the filling tube. However, there are some people who do not pay much attention to them, and they bring impurities into the tank and block the urea pump of the urea tank. In order to prevent impurities, pure water must be used when cleaning the SCR, not tap water.
The behavior of adding water to replace urea should be denied and resisted. The correct use of urea for vehicles. Urea is alkaline and has great corrosion to copper, cast iron, solder, and cast aluminum. Improper filling and overflow of urea can contaminate tanks and vehicles.
In addition, although urea itself has no major harm to the eyes and skin, it can also cause slight irritation to the human body. In case of skin contact, wash the exposed skin with plenty of soap or water. If it comes in contact with the eyes, open the upper and lower eyelids and rinse with water.
Urea filters have been used in the National IV models to filter out impurities in the urea solution and protect the SCR post-processing system.
● Keep away from light and dust during storage-use as soon as possible after opening to avoid over-temperature and under-temperature. Urea needs to be protected from light and high temperature during transportation. *The best transportation and storage temperature should be kept between -5℃-25℃. In addition, urea for vehicles will crystallize when the temperature becomes lower, and the volume expansion will increase to 7%. If the urea is too full, keep the storage volume ratio below 90%. High temperature will cause the decomposition of urea. Generally, the storage temperature of urea is related to the storage time of urea.
Car Urea Need to pay attention to the use of car urea. We can see from the table that most areas in the country store urea solution due to temperature, and the shelf life varies from half a year to three years. The product performance is usually stable within half a year.
Avoid dust during transportation and prevent damage. If urea is stored in a dirty and dusty place, the solution will be contaminated with impurities. When driving, usually a few barrels of urea are also used to prevent the urea solution from running out of power limit. During the carrying process, the card friend needs to take necessary shock-proof measures for the urea packaging to avoid leakage from the bumpy road and corrode the vehicle.
The storage of car urea is very important. The urea solution is easy to be contaminated by impurities or grow algae after being exposed to the sun. Moreover, the decomposition of urea itself produces ammonia loss, which causes the urea to deteriorate due to volatilization of the solution. According to the recommendations of domestic urea solution manufacturers, if the package is opened, it should be stored as required and used up within 30 days.
We can see that the concentration of vehicle urea solution and the presence or absence of impurities are critical to exhaust gas treatment. If you use water, agricultural urea, buy a “counterfeit” urea solution with a substandard concentration, or cause the qualified urea solution to deteriorate during storage and filling. It not only affects the conversion efficiency of nitrogen oxides, but also causes the loss of ammonia, and even directly destroys the SCR system, affecting the normal operation of the vehicle, and failing to meet the emission standards.

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