View EW Stats
Jump to content
Engineering Wall


Virgo

Members
  • Content count

    10
  • Joined

  • Last visited

Community Reputation

0 Neutral

About Virgo

  • Rank
    Member
  1. High and low temperature alternating humidity and heat test box is a necessary test equipment in aviation, automobile, household appliances, scientific research and other fields. It is used to test and determine the parameters and performance of electrical, electronic and other products and materials after high temperature, low temperature, alternating humidity and heat or constant temperature environment changes. The refrigeration cycle in the test chamber is composed of two isothermal processes and two adiabatic processes. The process is as follows: the refrigerant is adiabatically compressed to a higher pressure by the compressor, the exhaust temperature is increased by consuming energy, and then the refrigerant is exchanged through the isothermal ground of the condenser and the surrounding medium to transfer heat to the air. The surrounding media. The refrigerant is cooled by the adiabatic expansion of the interception valve, and the refrigerant temperature decreases. Finally, the refrigerant absorbs heat from the object with higher temperature isothermally through the evaporator, so that the temperature of the cooled object decreases. The design and application of energy regulation technology in the refrigeration system for the purpose of temperature reduction by starting the cycle again and again. An effective treatment method can not only ensure the normal operation of refrigeration units, but also effectively regulate the energy consumption and refrigeration capacity of the refrigeration system, so as to reduce the operating cost of the refrigeration system to a more economical level. The state of the state. Feilong Jiangli company specializes in producing water pumps for 40 years.
  2. Virgo

    Salt spray test

    Salt spray test is mainly used for testing salt spray corrosion resistance of galvanized and color coated products. There are two kinds of salt spray box: two kinds of roof salt spray box and spherical salt spray box. The spherical salt spray testing machine is more reasonable because of its reasonable structure design, the spray in the box is more uniform, but its price is higher, so it is seldom used. The parameters of salt spray testing machine can not be changed generally. If it needs to be changed, it is necessary to do a comparative tracking test to ensure the accuracy of the test. After the test sample is ready, if the surface is dirty, greasy stains, can be washed with clean water, or wipe cloth to remove, if not removed, the test data can not be referred to, need to be re-sampled. The sample should not be placed too much in the salt spray box, and the distance between the 1 fingers should be kept between the samples. To prevent changes in the test settings, the daily amount of fog should be recorded. When the salt spray test is taken out regularly for observation, only clean water can be used to wash and air-dry the surface of the sample. Do not wipe the surface of the sample with a dishcloth, because the dishcloth will remove the surface white rust. The position of the sample in the salt mist box should not be fixed. The position of the sample in the salt mist box should be changed after each observation. When the salt spray test machine is disused for a long time, the water in the salt spray box should be released. At the same time, the water in the saturated pail should also be released. https://s1.ax1x.com/2018/08/22/Po50z9.jpg
  3. Plastic is a kind of macromolecule material which is produced by complex chemical reactions such as polymerization, resin bonding, resin addition, condensation and so on. Properties: It is a light material (1/8 of steel), high specific strength, good chemical stability, corrosion resistance, good insulation, wear resistance, sound absorption, easy processing and molding. The main applications are: Installations: dashboard and gasket, sundries box, steering wheel, joystick, interior trim panel, seat armrest, door lining, various filling materials, etc. External fittings: sealing strip, bumper panel, fender, skirt edge, trim strip, hose, shock absorber gasket, handle, etc. Others: air filter housing, fan blades, various sensors, electrical appliances, and some gear. With the continuous improvement of advanced engineering plastics in performance, it is being developed and applied in automobile engine cover, roof, luggage rack and other parts. Plastics are divided into thermoplastics and thermosets. Thermoplastic softens after heating, has plasticity, machinability, and hardens after cooling; if it softens after reheating, hardens after cooling. This process can be repeated and has no effect on its structural properties. For example, polyfluoroethylene, polystyrene, polyamide (also known as nylon) and so on, they have simple molding process, high production efficiency, certain mechanical properties, but low heat resistance and rigidity. Thermoplastics are most widely used in automobiles. Commonly used are: ABS (acrylonitrile butadiene styrene), PP (polypropylene), PE (polyethylene) and so on. Thermosetting plastics react chemically when heated and harden after solidification; they cannot be softened by reheating. Such as phenolic resin, epoxy resin and so on. They are highly heat-resistant, pressure resistant and difficult to deform, and are relatively inexpensive, but the molding process is complex and the production efficiency is low.
  4. [Feilong Jiangli Edition] Heat treatment of steel parts is a process that changes the structure of steel by means of heating, heat preservation and cooling, so that the required properties of steel parts can be obtained. The heat treatment of steel varies according to the way of heating and cooling. Annealing: A heat treatment process in which steel is heated to a certain temperature for a period of time and then slowly cooled to room temperature with the furnace; the purpose is to reduce hardness, improve cutting performance, improve plasticity and toughness, eliminate structural defects in steel and eliminate internal stress. Normalizing: Normalizing is a heat treatment process in which the steel is heated to a critical temperature of 50-70 degrees above, fully insulated, and then cooled in the air; the purpose is basically the same as annealing, but the strength and hardness of normalized steel is higher than that of annealed steel. Quenching: quenching is a heat treatment process in which the steel is heated to 30-50 degrees above the critical temperature and cooled rapidly in the cooling medium after heat preservation; the commonly used cooling medium is water, mineral oil, salt, alkali water solution, etc. The main purpose of quenching is to improve the hardness and strength of the steel. Tempering: A heat treatment process in which hardened steel is reheated to a temperature below a critical temperature for a period of time and then cooled in air or oil to reduce or eliminate internal stress, improve toughness and plasticity, adjust hardness and reduce brittleness, and ensure that the shape and size of the steel remain unchanged. Surface hardening: Surface hardening is a local quenching method in which the surface of a steel piece is hardened to a certain depth while the central part remains unquenched; the purpose is to obtain a higher strength, wear resistance and fatigue strength on the surface of the steel piece, while the center still has sufficient plasticity and toughness. CHEMICAL HEAT TREATMENT: CHEMICAL HEAT TREATMENT means that steel parts are heated, kept warm and cooled in a certain medium, so that some elements in the medium penetrate into the surface layer of steel parts, thereby improving the surface properties; the purpose is to improve the hardness, wear resistance, corrosion resistance and oxidation resistance of the surface layer of steel parts; mainly carburizing, nitriding, carbonitriding, etc.
  5. There are many kinds of materials used to produce automobiles: iron and steel, non-ferrous metals, plastics, rubber, glass, ceramics and so on. According to statistics, in recent years, the weight composition ratio of the main materials of an ordinary car is approximately 65%-70%, 10%-15% of non-ferrous metals, and 20% of non-metallic materials. Various new materials, such as light metal materials, composite materials, high-tech synthetic materials, are increasingly used in modern automobiles. Metal materials have various properties. It has physical and chemical properties, mechanical properties and process properties. Physical and chemical properties refer to the properties of metal materials under various physical conditions and the ability to resist the erosion of various chemical media. Density: mass per unit volume; thermal conductivity: the ability to conduct heat; electrical conductivity: the ability to conduct electric current; thermal expansion: the ability to increase volume when heated; melting point: the temperature when the solid state becomes liquid; magnetism: the magnetic conductivity of metallic materials is called magnetism; corrosion resistance: metal resists the occurrence of the surrounding medium at room temperature The ability of chemical reactions to be destroyed; oxidation resistance: the ability of metals to resist oxidation at high temperatures. Mechanical performance refers to the resistance of metallic materials under various loads (external forces). It has the following indicators: Impact toughness: the ability of metal materials to resist failure under impact loading is called impact toughness. Fatigue strength: Fatigue cracks occur in metal materials under cyclic loading and lead to fracture called fatigue fracture; the maximum stress that does not produce fracture under repeated cyclic loading is called fatigue strength; the fatigue strength is measured by fatigue test; when the number of stress cycles of metal materials reaches 107, the parts are still Without breaking, the maximum stress at this time can be used as fatigue strength. For some high strength steels, the maximum stress at 108 cycles of stress is their fatigue strength. Cutting performance: cutting performance refers to the difficulty of machining metal materials. Heat treatment performance: heat treatment performance refers to the ability of metal materials to adapt to various heat treatment processes. https://s1.ax1x.com/2018/08/22/Po50z9.jpg
  6. The damage of automobile parts mainly includes four types: deformation, fracture, corrosion and wear. The first three types of damage are usually repaired by cold working, hot working or gluing. If the general parts deformation can be cold-pressed or hot-pressed after correction for mechanical repair; shaft parts can be broken by inlaying, welding, forging and other methods to repair; cylinder block water jacket cracks can be repaired by welding, riveting or adhesive methods. Parts wear is the most common damage. Parts that have not worn out beyond the specified repair size are processed according to repair size. Parts that have worn out beyond the repair size are repaired by surfacing, spraying, electroplating and other metal covering processes and adhesive methods. Electroplating Repair Method This method is to use the part to be repaired as the cathode, so that the metal cations in the electrolyte move toward the part (cathode) under the action of electric field force, and deposit on the surface of the part. The advantage of the electroplating method is that it can obtain a good wear resistant layer and no distortion of the parts. Chromium plating is often used to repair automobile parts, followed by iron plating chromium plating and iron plating are both electrode crystals, with similar ultra-fine grains and high dislocation structure and large internal stress, and is stratified, with a large number of microcracks. But the chromium plating layer and the iron plating layer have their own characteristics, such as high hardness, good wear resistance, and prolonging the service life of the parts. The disadvantages are low current efficiency, slow deposition, thin coating, high cost, and highly toxic chromium anhydride, serious environmental pollution. The electrolyte temperature of iron plating used to be above 90 C, which can reduce the internal stress of the coating and prevent peeling, but the hardness of the coating is on the low side. In 70s, the wear resistance and the bonding strength of the coating were increased by using low temperature iron plating at 45 C. Iron plating also has the advantages of fast accumulation, low cost and no pollution to the environment.
  7. The significance of automotive parts repair is to repair old and waste, reduce the consumption of new parts, thereby saving raw materials, energy and manpower for manufacturing parts. The damage of automobile parts mainly includes four types: deformation, fracture, corrosion and wear. The first three types of damage are usually repaired by cold working, hot working or gluing. If the general parts deformation can be cold-pressed or hot-pressed after correction for mechanical repair; shaft parts can be broken by inlaying, welding, forging and other methods to repair; cylinder block water jacket cracks can be repaired by welding, riveting or adhesive methods. Parts wear is the most common damage. Parts that have not worn out beyond the specified repair size are processed according to repair size. Parts that have worn out beyond the repair size are repaired by surfacing, spraying, electroplating and other metal covering processes and adhesive methods. Automatic surfacing is to install parts on the surfacing machine and turn them on side. Commonly used automatic surfacing has three technologies: vibration surfacing, carbon dioxide protection welding and submerged arc welding. Carbon dioxide protection welding is carried out under the covering of carbon dioxide gas. Because carbon dioxide can react with carbon in molten iron to form carbon monoxide at high arc temperature, some carbon monoxide gases escaped from molten iron pool and become pores in the welding layer, thus affecting the surfacing quality. Therefore, in order to reduce the porosity, carbon dioxide shielded welding mostly uses special low-carbon manganese-silicon alloy steel wire with low carbon content and sufficient deoxidizer. The wire diameter is 0.4-0.6 mm. The surfacing layer has high strength, few pores and no cracks, but the hardness is low. This method is suitable for repairing cab, leaf plate and other thin plate parts.
  8. Rolling bearings on automobiles include ball bearings, roller bearings, tapered bearings and needle roller bearings. They often work under high speed and heavy load conditions and bear considerable alternating loads. Therefore, rollers and raceways often produce serious wear, fatigue spalling, fracture, ablation (that is, high temperature annealing, serious, the color is purple black, similar to blue) and other phenomena. When rolling bearing, a component usually does not need to decompose and check the damage condition of each part. When inspecting, the bearings are cleaned and rubbed. The quality of the bearings can be appraised by means of external inspection, idling test and internal clearance inspection if necessary. (1) appearance check. In the inspection, if the following damage phenomena are found, they should be replaced in time. Rollers (ball, cylindrical roller, tapered roller, needle) and internal and external raceways are discolored by ablation; in the internal and external raceways of bearings, there are impact marks, marks and scratches; in the internal and external raceways of bearings, rolling bodies (ball, cylindrical roller, tapered roller, needle) on the occurrence of cracks, metal delamination, scaly peeling and a large number of (ball, cylindrical roller, tapered roller, needle) Usually more than one third of the area) black spots; excessive wear in the groove of the retaining roller, the roller can fall out by itself; due to tapered roller wear, its small end of the working face protruding out of the bearing outer seat ring end; tapered roller bearing inner ring large end of the internal end of the notch and metal spalling. In the inspection of rolling bearings, if only minor corrosive black spots are found in the bearings and minor defects in the cage are found, without affecting the rotation of the bearings, they can generally continue to be used. (2) idling inspection. The experiment mainly depends on whether the bearing rotates flexibly, whether there is noise or whether it is stuck or not. The inhomogeneity of the bearing rotation can be judged from the feeling on the hand (the old bearing is allowed to have a slight noise). (3) internal clearance check. The measurement of internal clearance and wear of ball bearings can be judged by measuring their radial and axial clearance. Axial clearance inspection: the bearing outer seat ring is placed on two cushion blocks, and the inner seat ring is suspended, and then a small plate is placed on the inner seat diagram, the dial stylus against the center of the plate, the maximum allowable value of axial clearance is 0.20 ~ 0.25 mm. Radial clearance inspection: Place the bearing on a flat plate so that the dial gauge stylus against the bearing outer seat, and then hand press the bearing inner ring, the other hand reciprocating push the bearing outer ring, the number of meter needle swing is the radial clearance of the bearing. The maximum allowable value of radial clearance is 0.10~0.15mm.
  9. Grinding is the process of grinding metal with a grinding wheel on a grinder. Grinding is one of the main methods of finishing. In the automobile industry, the grinding machine accounts for about 25%. Therefore, finishing and grinding of hardened materials is a common method. In addition, grinding is easy to automate, and is conducive to efficient production. Grinding has the following characteristics: 1. The grinding wheel has high abrasive hardness and good heat resistance, so it can grind hard materials that metal tools can not process. 2. Grinding can remove very thin and very fine chips, the chip thickness is generally only a few microns, therefore, has a strong correction ability, processing accuracy can reach T6~IT5, surface roughness of Ra0.1 micron. 3. high grinding speed. 4. The cutting temperature is high, and the instantaneous maximum can reach 1000 degrees Celsius. Therefore, the grinding surface is easy to produce residual stress, burn and crack. According to the geometry of the object, grinding can be divided into outer circle, inner circle, plane and formed surface. By clamping and driving the workpiece, it can be divided into centering grinding and centerless grinding. According to the feed direction, it can be divided into longitudinal feed and transverse feed. According to the working surface types of grinding wheels, they can be divided into peripheral grinding, end grinding and peripheral grinding. The types of grinding machines commonly used in automobile manufacturing are ordinary grinder and special grinder. Ordinary grinder includes: cylindrical grinder, internal grinder, surface grinder, centerless grinder, etc. Special grinding machines include camshaft grinder, crankshaft grinder, cross shaft grinder and so on. https://s1.ax1x.com/2018/08/22/Po50z9.jpg
  10. Repairing methods for worn parts can be divided into two categories: machining worn parts to restore the correct geometric shape and fit characteristics, and obtaining new geometric dimensions. Surfacing, spraying, electroplating and electroless plating are used to supplement the worn parts, or expanding (reducing) upsetting is used to increase (or reduce) the size of the worn parts, and then mechanical processing is carried out to restore the nominal size, geometry and surface roughness. Repair of deformed parts can be done by pressure correction and flame straightening. The cracks and damages on the parts can be repaired by welding, brazing, bench work or bonding. The worn parts are machined by repairing dimension method and inserting sleeve method to make them have correct geometry. Repair dimension method is widely used in automobile repairing. In order to balance the service life of parts, repair dimension method is used in many parts, such as cylinder, piston, piston ring, piston pin, crankshaft and bearing, which have high wear rate and short service life. In automobile use, some of them are only local wear or abrasion. When the structure and strength permit, the wear parts can be reduced (shaft) or enlarged (hole) to a certain size (usually 2-3 mm) and then embedded into a sleeve by interference fit method to restore the basic size of the repair process. Such as: cylinder liner, valve guide and all kinds of bushing. Thanks for the help of Feilong Jiangli
×