Quantcast
Jump to content

Erica Zhu Feilong Jiangli

Members
  • Content count

    17
  • Joined

  • Last visited

Community Reputation

0 Neutral

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. Erica Zhu Feilong Jiangli

    Corrosion wear of automotive parts

    The phenomenon of loss of metal in the relative movement of parts is known as the wear of parts. The occurrence of wear will cause changes in the shape, size and surface properties of the parts, which will gradually reduce the working performance of the parts. Wear is sometimes beneficial, such as running-in. According to different friction principles, wear can be divided into abrasive wear, adhesive wear, fatigue wear and corrosion wear. Corrosion wear: The abrasion on the friction surface of parts caused by chemical or electrochemical reaction due to the action of external medium is called corrosive wear. Corrosion wear is divided into oxidation corrosion wear, chemical corrosion wear and fretting wear. Chemical corrosion wear: The abrasion caused by chemical reaction directly between the metal and the external medium is called chemical corrosive wear. When a part is working in corrosive gas or liquid environment, a chemical reaction film is formed on the surface of the component. The bonding strength between the reaction film and the base metal is usually low. When the parts move relative to each other, the chemical reaction film will fall off and cause the chemical corrosion and wear of the parts. Electrochemical corrosion wear: The abrasion caused by the electrochemical reaction of metal in the external medium is called electrochemical corrosion wear. Fretting wear: Fretting wear is called fretting wear, which is caused by alternating load or vibration on the surface of interference fit of parts. Cavitation: Cavitation erosion is a fatigue exfoliation phenomenon on the surface of a solid moving relative to a liquid due to the local high temperature caused by bubble rupture and high impact pressure.
  2. Erica Zhu Feilong Jiangli

    Classification of stamping process

    The stamping process can be divided into different classes according to different standards. (1) according to the different deformation properties, it can be divided into separation process and forming process. Separation process: the material is processed under external force to produce deformation, as used in the deformation part of the equivalent stress reached the shear strength of the material, the material will produce shear cracking and separation, thus forming a certain shape and size of the parts. These stamping processes are generally referred to as separation processes, such as tailoring, punching, blanking, and cutting. Forming process: under the action of external force, the equivalent stress acting on the deformed part of the material is between the yield limit and the strength limit of the material. The material only produces plastic deformation, so as to obtain a certain shape and size of the parts. These stamping processes are collectively called forming processes, such as bending, drawing, forming and other deformation processes. (2) according to the basic deformation mode, it can be divided into blanking, bending, drawing and forming. Punching: Punching, such as punching, blanking, etc., is a process in which materials are cut apart along closed or non-closed contours. Bending: The stamping process of bending a material into an angle or shape is called bending, such as bending, crimping, twisting, etc. Drawing: The process of drawing a flat blank into a hollow part, or further changing the shape and size of the hollow part with a drawing die, is called drawing. There are thinner drawing and thinner drawing. Forming: The stamping process that causes material to deform locally to change the shape of a part or blank is called forming, such as flanging, shrinkage, etc.
  3. Erica Zhu Feilong Jiangli

    Stamping process

    Stamping technology is an advanced metal processing method. It is based on the plastic deformation of metal. It uses dies and stamping equipment to exert pressure on the sheet metal under normal temperature conditions, so that the sheet metal produces plastic deformation or separation, so as to obtain parts with certain shape, size and performance. Stamping technology is widely used in automobile industry, and is the key technology in automobile body manufacturing. Stamping features: (1) it is easy to operate, easy to realize mechanization and automation, and has high productivity. (2) The dimension precision of the part is guaranteed by the mould. Generally, it can be used for assembly without cutting, so the quality is stable. (3) it is possible to obtain parts with complex shapes which cannot be machined or processed by other metal processing methods. (4) Generally, it does not need to heat the blank, nor does it need to remove a large number of metals like cutting, so it not only saves energy, but also has a high utilization rate of materials. (5) The raw materials used are rolled sheets or strips, and the surface of the material is generally not damaged during the stamping process, so the surface quality of the stamping parts is better. The stamping process is carried out on punching presses or presses. Special punching tools are equipped on punching presses or presses.
  4. Erica Zhu Feilong Jiangli

    Introduction of welding method

    There are many kinds of welding methods. Several typical welding methods are introduced below. (1) electrode arc welding Electrode arc welding is a method of welding metal by using coated electrode as electrode and filler metal, arc burning between the end of electrode and the welded surface to melt electrode. Characteristics and applications: the electrode arc welding equipment is simple, light and flexible. It can be used to weld short seams in maintenance and assembly, especially in difficult parts. (2) resistance welding Resistance welding (RW) is a method of using resistance heat generated by electric current passing through the contact surface of the weldment to heat the part of the weldment to a high plastic or semi-melting state, and to crystallize and solidify the welded joint under pressure. Features and applications: easy to realize automation, high productivity; no filler metal, welding deformation is small; welding equipment is complex, power consumption is large. It is usually used for mass production. (3) gas shielded arc welding Gas shielded arc welding is to use gas as arc medium and protect arc and welding area by arc welding. Argon and carbon dioxide are the main protective gases. Features and applications: heat concentration, faster welding speed, less deformation after welding, is conducive to the mechanization and automation of welding process. Usually used for welding thin plates. (4) brazing Brazing refers to the method of using metal materials with lower melting point than the parent material as the solder, wetting the parent material and filling the gap between the workpiece interface with liquid solder and diffusing with the parent material. Features and applications: low heating temperature, small welding stress and deformation; smooth welded joints; can weld multiple seams at the same time, high productivity; simple welding equipment, less investment; low welding strength. Brazing is not suitable for welding of general steel structure and heavy load and moving parts. It is mainly used for manufacturing precision instruments, electrical components, dissimilar metal components and complex sheet structures.
  5. Erica Zhu Feilong Jiangli

    Free forging of parts blank

    Free forging is a kind of forging method which uses impact force or pressure to make the metal form freely in all directions between the top and bottom of the anvil surface without any restriction to obtain the required shape, size and certain mechanical properties of the forging. The equipment of free forging can be divided into two categories: forging hammer and hydraulic press. The hammer used in production is air hammer and steam air hammer. Hydraulic press is the only way to produce large forgings by using the static pressure generated by liquid to deform the blank. Basic process of free forging (1) The upsetting-one upsetting is a forging process which makes the cross-section of blank larger and the height smaller. There are two kinds of upsetting: integral upsetting and partial upsetting. (2) Drawing-drawing is contrary to upsetting, and is a forging process which makes the length of blank increase and the cross section decrease. (3) The punching process of punching holes or blind holes on billets. Characteristics and application of free forging Free forging is to control the shape and size of forgings by manual operation, so the forgings have low precision, large machining margin, high labor intensity, and low productivity. Therefore, it is mainly used in single-piece and small-batch production with simple structure and shape of forgings.
  6. Erica Zhu Feilong Jiangli

    Special casting for parts blank

    Special casting has the characteristics of high precision, good mechanical properties, high productivity and good working conditions. Special casting methods are as follows: (1) Metal mold casting: the method of injecting liquid metal into a mold made of metal to obtain a casting. Features: One mold multi-casting, high casting accuracy, good mechanical properties, but high cost, mainly used for mass production of copper, aluminum, magnesium and other non-ferrous alloy castings. (2) Investment casting: a casting method in which wax is made into a pattern, coated with several layers of refractory paint, and heated to make the pattern melt, flow out, and bake into a pattern with a certain strength, then poured and removed. Process features: take the melting pattern as the starting mode. The precision of casting is high, and it is a method of little cutting. Its equipment is simple and production quantity is not restricted. It is mainly used for mass production and mass production. The drawback is that the process is complex and the production cycle is long. (3) Pressure casting: a casting process in which molten metal is rapidly pressed into the cavity of a metal mold under high pressure and solidified under pressure to obtain a casting. Process features: high speed and high pressure is applied on the basis of metal mold casting to improve metal fluidity. It is mostly used for mass production of precision casting of non-ferrous alloys, such as aluminum, copper and magnesium. (4) Centrifugal casting: a casting method in which molten metal is poured into a high-speed rotating mold to solidify the liquid metal under the action of centrifugal force. Process features: compact structure, good casting quality. It is used to produce hollow castings.
  7. Erica Zhu Feilong Jiangli

    Sand casting for parts blank

    The materials used in making molds are called molding materials. The sand molds are mainly molded sand and core sand, which are composed of sand, binder and additives. 1.Molding materials should have the following properties: (1)Plasticity: molding sand and core sand are easy to form under the action of external forces. (2)Sufficient strength: molding sand and core sand are not easy to destroy under external force. (3)Fire resistance: molding sand and core sand are difficult to soften, sinter and adhere at high temperature. (4)Permeability: molding sand and core sand must be easy to ventilate after compacting. (5)Concession: molding sand and core sand can be compressed when cooled. 2.Pattern and core box The pattern and core box are tools for making moulds and cores. The shape of a casting to form a shape equivalent to the external shape of the casting. The core forms the inner cavity shape of the casting, and the core box is the tool for making the core. Sand moulds and core boxes are used for multi-purpose wood casting. Metal mold, plastic mold and other patterns for special casting. 3.Modeling method According to the different methods of modeling operation, it can be divided into: (1)Manual molding: sand filling, compacting, mold lifting and so on mainly have the manual completion, the operation is flexible, the productivity is low, mainly uses in the single piece small batch production. There are many specific methods of manual modeling: whole mold modeling, three-box modeling, scraper modeling, false box modeling and so on. (2)Machine Modeling: Mechanization of sand filling, compacting and moulding, high productivity and large investment, mainly used for mass production 4.Technical problems to be solved in sand casting (1)The choice of pouring position: the main processing surface and large plane of the casting should be facing down, and the part of the Dian wall of the casting should be placed at the bottom. (2)Selection of parting surface: plane parting surface should be adopted as far as possible, the number of parting surface should be as small as possible, so that all or most of the castings are placed in the same sand mold. (3)Drawing inclination and casting fillet: In order to start the mold conveniently, the mold should have a certain drawing inclination, the higher the mold, the smaller the slope value: the inner wall inclination is larger than the outer wall inclination. In order to prevent the casting from producing stress and cracks at the wall joints and corners, the casting wall joints and corners should be designed into rounded corners.
  8. (1) the concept of casting Molten metal is poured into the mold cavity, and after solidification and cooling, a certain shape of parts or parts blank is obtained. This method is called casting. The blank or parts obtained by casting are called castings. Castings generally account for about 20% of the vehicle's self weight, ranking only second after steel consumption. (2) casting method Sand mold casting: Liquid metal fills the mold cavity completely by gravity, and the raw material for forming the mold is mainly sand. Special casting: all kinds of casting methods other than sand casting. (3) characteristics and application of casting It is easy to shape and adaptable. The production cost is low and more economical. The microstructure and properties of casting materials are poor. Casting is generally used in the manufacture of automobile box, shell, bracket parts, such as: engine cylinder block, cylinder head, intake (exhaust) manifold, crankshaft, camshaft, ram speed box shell, chassis rear axle housing, killing bracket, brake drum, brake disc.
  9. Erica Zhu Feilong Jiangli

    What are auto parts?

    Automobile parts refer to the components of each unit of the automobile and all consumable materials serving the automobile. They can be divided into automobile parts, Automobile standard parts and automobile materials. The following is a detailed introduction. (1)Auto parts are divided into parts, assemblies, component, and body panels. Parts: the basic manufacturing unit of a car. It is an integral part that can no longer be disassembled. Such as: piston ring, piston, valve, impeller and so on. Assembly: a combination consisting of more than two parts and acting as a single part. For example, a connecting rod with a cover, a pair of bearing shells, and a cylinder head with a valve guide. Component: a combination consisting of several parts or assemblies, but can not function independently. For example, transmission cover, cooler cover, automobile steering connector, water pump and so on. Sometimes it is also called "half assembly". Body panels: formed by sheet metal stamping, welding, and covering automotive body parts such as: radiator cover, leaf plate, etc. (2) automotive standard parts Designed and manufactured according to the national standards, the same parts are unified in shape, size, tolerance, technical requirements, and can be used in a variety of instruments and equipment, and interchangeable parts are suitable for automotive standard parts such as bolts, gaskets, pins, keys, etc. (3) automotive materials Automobile operating materials, such as various oils, solutions, automotive tires, accumulators, standard bearings (non-special), etc. Most of the products produced by non-automotive industry and used by automobiles, generally not included in the catalogue of various types of automotive accessories, also known as "horizontal products". https://s1.ax1x.com/2018/08/22/Po50z9.jpg
  10. Automobile surface drawing parts have the following characteristics: 1.Deformation characteristics The deformation characteristics of large curved surface parts are as follows: the periphery is deep drawing, and the interior has bulging components. The surface shape is supplemented by the exterior material of the pressing surface and the interior by the material extension to meet the bulging requirements. At the same time, due to the deep drawing depth and complex shape, the distribution of deformation parts is uneven. Therefore, controlling the direction and velocity of material is extremely important. The part of large curved surface is easy to wrinkle and crack easily. 2.There must be enough stable blank holder force. Large curved surface parts require not only certain drawing force, but also enough stable blank holder force in the process of drawing. This kind of workpiece is often a large contour size, deep space surface, so the need for deformation and blank holder force are larger. In the ordinary single-action press with air cushion, the blank holder is only about 1/6 of the nominal tonnage, and the blank holder force is not stable, it is difficult to meet the technological requirements of such parts, so in a large number of production, the drawing of such parts are carried out on double-action press. The double-action press has two sliders for drawing and blank-holder, i.e. inner slider and outer slider. The blank-holder force can reach more than 40% - 50% of the total drawing force. It can satisfy the requirement of uneven distribution of deformation around the workpiece, and the blank-holder force is stable, and it is easy to get the deep-drawing parts with better stiffness. 3.The drawing parts must have enough stiffness. Most of these parts are used as the exterior of the machine, requiring sufficient stiffness (no trembling and noise in use) and dimensional stability (to ensure the quality of welding and assembly). This requires that all parts of the material be subjected to uniform tensile stress (ideally a two-way tensile stress state) in the drawing process, and that the tensile stress exceeds the yield limit, but is lower than the strength limit, so that the elastic recovery of the workpiece is reduced to a minimum, so that the shape is not distorted, but also not rupted.
  11. In order to realize drawing forming, it is necessary to add some materials with certain shapes outside the body of the panel to form the drawing process parts. These added parts are called process supplement parts. Generally speaking, the supplementary part of the process extends outward along the flanging line of the workpiece, then gradually changes its shape, turning the sharp corner of the original product into a spherical corner, turning the original unclosed area into a closed cavity, gradually changing the original depth of different drawing into a more uniform drawing depth, and changing the supplementary part into a spherical corner. The side wall of the drawing part improves the positioning condition of the stamping part in the post construction process. The process supplement includes two parts: the process extension surface and the pressing surface, which will be removed in the subsequent process. Therefore, under the condition that the satisfactory drawing parts can be drawn, the supplementary parts of the drawing process can be reduced as much as possible. The main function of the process extension surface is to make the drawing parts easy to form, including forming the side wall with simple shape, and increasing the local wall height, so that the drawing depth is more uniform, the concave surface shape is simplified, and the material is synchronized. Deformation, in order to prevent chattering lines and offset lines: the part of the drawing piece in contact with the blanking ring is called the blanking surface, it can be part of the body of the drawing piece, can also be made up of process supplements: in the panel drawing, in order to prevent wrinkling, the use of blanking ring to press the blank, there must be a blanking surface. https://s1.ax1x.com/2018/08/22/Po50z9.jpg
  12. Stamping direction selection is an important part in die design. It not only determines whether a satisfactory drawing piece can be drawn, but also affects the number of supplementary parts and the shape of blanking surface. The stamping direction includes two aspects, that is, the location of the production and the processing direction of the technological characteristics. Locally, each process feature has its best punching direction. However, the stamping process of panel often contains many process features, and the optimal stamping direction of each process feature is not consistent. Therefore, to determine the stamping direction of a process feature, not only the stamping feasibility of this feature should be considered, but also the coordination with other process features should be considered. Therefore, in the process of process design, it is an optimization problem to determine the stamping direction of all process characteristics of a process. Most automotive panels are of complex spatial curved surface shape, which is formed by sheet metal drawing. The deformation is very complex, so it is necessary to optimize the stamping direction. In the process of optimizing stamping direction, the material flow in the stamping process is analyzed firstly, and the principle of determining the stamping direction is put forward. According to the principle, a mathematical model is established, and then the CAD technology is used to optimize the stamping direction. https://s1.ax1x.com/2018/08/22/Po50z9.jpg
  13. Erica Zhu Feilong Jiangli

    Engine cooling mode

    According to the cooling medium used, engine cooling methods can be divided into water-cooled and air-cooled. 1. Water-cooled one by one with water as the cooling medium, heat first from the machine to water, by the flow of water to heat away and then into the atmosphere. After heat dissipation, the water flows back to the hot part again. The normal working temperature of the engine can be maintained by properly adjusting the water and cooling intensity. At the same time, hot water can also be used to preheat the engine, which is convenient for starting in winter. The structure of water-cooled cooling system: water pump, radiator, fan, thermostat, expansion tank, warm air, engine water jacket, cooling pipe. 2. the heat of air-cooled parts is directly scattered into the atmosphere. At present, most of the cars are water-cooled. https://s1.ax1x.com/2018/08/22/Po50z9.jpg
  14. Automobile engine is a kind of machine which provides power for automobile, and it is the heart of automobile. It affects the power, economy and environmental protection of automobile. According to different power sources, automotive engines can be divided into diesel engine, gasoline engine, electric vehicle motor and hybrid power. Engine overheating will cause the following hazards to the car: 1) reduce inflation efficiency and reduce engine power. 2) the tendency of early combustion and deflagration increases, resulting in early damage to parts due to additional impact loads. 3) the normal clearance (thermal expansion and cold contraction) of the moving parts is destroyed, the movement block, the wear aggravate, or even damage. 4) the deterioration of lubrication aggravates the friction and wear of parts. 5) the mechanical properties of parts are reduced, resulting in deformation or damage. And if the engine is too cold, it will also do harm to cars. 1) When the temperature of the mixture (or air) entering the cylinder is too low, the quality of the combustible mixture is poor (poor atomization), which makes it difficult to ignite or slow combustion, resulting in a decrease in engine power, an increase in fuel consumption (excessive heat loss, fuel condensation into the crankcase). 2) Water vapor in combustion products easily condenses into water and forms acids with acidic gases, which aggravates the erosion of the body and parts. 3) Unvaporized fuel scouring and diluting the oil film on the surface of parts (cylinder wall, piston, piston ring, etc.), which aggravates the wear of parts. 4) Increased viscosity of lubricating oil, poor fluidity, resulting in poor lubrication, worsening parts wear and power consumption. https://s1.ax1x.com/2018/08/22/Po50z9.jpg
  15. The greater the damping force of the shock absorber, the faster the vibration is reduced, but the effect of the parallel elastic elements can not be fully exerted. At the same time, the excessive damping force may also lead to damage to the connecting parts and frame of the shock absorber. In order to solve this contradiction between elastic elements and shock absorbers, the following requirements are put forward for shock absorbers. (1) In the compression stroke of the suspension, the damping force of the shock absorber should be small so as to make full use of the elasticity of the elastic elements to mitigate the impact. (2) In the suspension stretching stroke (the distance between the bridge and the frame) the damping force of the shock absorber should be large in order to reduce the vibration rapidly. (3) When the relative speed between the axle (or wheel) and the frame is too high, the shock absorber should be able to automatically increase the area of the liquid flow passage, so that the damping force is always within a certain limit to avoid excessive impact load. Cylinder shock absorber is widely used in automobile suspension system, and it can reduce vibration in compression and stretching stroke. It is called bidirectional action shock absorber, and a new type of shock absorber is adopted, which includes air-filled shock absorber and resistance adjustable shock absorber.
×

Copyright © 2018 AutoPartsForum.com Powered by Invision Community