Stamping is a manufacturing process that involves applying pressure to a material to deform it into a desired shape or size. There are various types of stamping processes utilized in the industry, each with its unique set of advantages and disadvantages. In this article, we will describe some of the most common types of stamping processes.
Overall, stamping is a versatile manufacturing process that plays a crucial role in the production of a wide range of metal parts and components. By understanding the different types of stamping processes, manufacturers can select the most suitable process for producing high-quality parts in an efficient and cost-effective manner.
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Blanking: Blankings are flat pieces of sheet metal that have been precisely cut and punched out from larger sheets of metal. Blanking is a process used to produce these flat pieces, and is ideal for producing large quantities of uniform, flat parts.
Coining: Coining is a stamping process used to create impressively flat and precise features - often used in creating coins or bearing seals.
Drawing: Drawing involves pulling a flat piece of metal through a die with a punch tool to form it into a three-dimensional shape. This process is commonly used in the creation of products such as automobile fenders, cans, and ship hulls.
Embossing: Embossing is the process of applying raised designs or patterns to a flat piece of metal by impressing the metal with a die. This process is popularly used in the production of decorations and signage.
Piercing: Piercing is the process of punching or drilling holes in a metal sheet. It is widely used in creating products such as luggage tags, name plates, and metal attachments.
Blanking and forming: Blanking and forming involve using a single die to create a part that has a variety of features, both flat and formed. It is a highly efficient process for creating complex parts.
Abstract: Energy saving and environmental protection are two major problems to be solved urgently by mankind. The World Summit on Sustainable Development was held in Johannesburg, South Africa, from 26 August to 4 September 2002. At the conference, IHS published "The Refrigeration Industry's Commitment to Sustainable Development and Mitigation of Atmospheric Changes," in which it is stated that the major challenge to the refrigeration industry is from global warming. The cause of the cooling industry affecting 80% of global warming is the carbon dioxide emissions. These indirect emissions are partly due to the production of energy required for the operation of the refrigeration unit. Keywords: thermal expansion valve electronic expansion valve principle control 1. Overview Energy-saving and environmental protection are two major human problems to be solved. The World Summit on Sustainable Development was held in Johannesburg, South Africa, from 26 August to 4 September 2002. At the conference, IHS published "The Refrigeration Industry's Commitment to Sustainable Development and Mitigation of Atmospheric Changes," in which it is stated that the major challenge to the refrigeration industry is from global warming. The cause of the cooling industry affecting 80% of global warming is the carbon dioxide emissions. These indirect emissions are partly due to the production of energy required for the operation of the refrigeration unit. Refrigeration, air conditioning and heat pumps consume about 15% of the world's production of electricity, which shows that the impact of indirect emissions is very serious. The paper also suggests that in the next 20 years, the refrigeration industry must set ambitions to achieve one of its goals: a 30-50% reduction in energy consumption per refrigeration unit. Refrigeration industry to protect the environment, energy efficiency should be used throughout the life cycle of refrigeration equipment. As one of the four major components of a refrigeration cycle, the throttling device plays a crucial role in the system. Choosing an appropriate throttling mechanism to match the refrigeration system is an important part of reducing the energy consumption of the entire refrigeration equipment. In this paper, the working principle of throttle mechanism and operation energy matching are analyzed, and the working principle of electronic expansion valve is analyzed emphatically. 2. The working principle of traditional throttling mechanism and matching The working principle of throttling is that when the working fluid flows through the valve, the refrigerant cross section suddenly shrinks, the fluid velocity increases, the pressure decreases, and the pressure drop depends on the ratio of the flow cross section shrinkage. The role of throttling institutions: 1, throttling buck. When the normal temperature and high pressure refrigerant saturated liquid flows through the throttle, into a low temperature and low pressure refrigerant liquid and produce a little flash gas. So as to achieve the purpose of absorbing heat to the outside world. 2, adjust the flow: the throttle valve through the temperature sensor outlet feel the refrigerant superheat degree changes to control the valve opening, adjust the flow of refrigerant into the evaporator, the flow and evaporator heat load to match . When the evaporator heat load increases when the valve opening also increases, the refrigerant flow increases, on the contrary, reduce the refrigerant flow. 3, control the degree of superheat: throttling mechanism has the function of controlling the evaporator superheat degree of the evaporator outlet, while maintaining the full utilization of the evaporator heat transfer area, but also to prevent damage caused by suction liquid compressor accident. 4, control the evaporation level: with liquid level control throttling mechanism has the function of controlling the evaporator level, both to maintain full use of the evaporator heat transfer area, and to prevent the suction liquid to reduce suction superheat. If the throttling mechanism to the evaporator supply volume and evaporation load is too large, part of the liquid refrigerant together into the compressor, causing wet compression or Chong Chong accident. On the other hand, if the amount of liquid supplied is too small compared with the load on the evaporator, the heat transfer area of ​​the evaporator part can not fully exhibit its effect and even the evaporation pressure will be reduced. In addition, the cooling capacity of the refrigeration system is reduced, the refrigeration coefficient is decreased, Device energy consumption increases. Throttle body flow regulation on the refrigeration unit energy saving play a very important role. Large central air-conditioning chillers commonly used throttle mechanism manual throttle, orifice, thermal expansion valve, float the main throttle. 2.1 Manual Throttle Manual throttle is the oldest type of throttle valve, its shape and general stop valve similar. It consists of the valve body, the valve core, stem, packing gland, cover, hand wheel and bolts and other components. The difference with the cut-off valve is that its spool is a needle or cone with a V-notch, and the stem adopts a fine thread. When turning the handwheel, the valve opening degree can be slowly increased or decreased, in order to ensure good regulatory performance. Manual throttle opening size, the need for frequent operator adjustments to adapt to load changes. Usually open degree of 1/8 ~ 1/4 laps, usually not more than one lap, open too large to play the role of throttling (expansion). The throttle is now replaced by an automatic throttling mechanism. 2.2 orifice plate orifice throttling mechanism consists of two orifice plates, using two throttling. Refrigerant through the first stage orifice plate, the refrigerant just reached the saturated liquid refrigerant line, and a slight flash of gas; as flash gas occupy part of the space, the flow is also fluctuating, resulting in the second stage into the orifice plate The flow of the fluid changes within a certain range (about 20%) to achieve the function of automatically adjusting the circulating amount of the refrigerant, the second-level orifice plate causes different pressure drop changes due to the fluctuating flow, and adjusts the pressure difference between the system and the low- After the dynamic equilibrium, stable expansion of the refrigerant to play the role of refrigeration and complete the entire refrigeration cycle. The design of primary and secondary orifice plates is based on: 1, the flow rate formula: q = ax Α x (2 x Δp x Ï) 1/2 2, chiller standard conditions: 12 ℃ / 7 ℃; 30 ℃ / 35 ℃. Chiller in standard conditions at full capacity operation, the orifice to the evaporator liquid supply and evaporation load to match. But the actual operation of the unit is often in variable conditions, variable load operation. In the case of large pressure drop, the evaporator load demand decreases (amplitude greater than 20%), orifice maximum allowance 20%, due to pressure increases, the actual orifice fluid volume than the evaporator load required Large, inspiratory superheat decreases, causing wet compression; In small pressure conditions, the evaporator load demand increased (amplitude greater than 20%), due to pressure drop, the actual evaporator liquid volume than the evaporator load required The amount of liquid is small, the suction superheat increases, the cooling capacity decreases, the cooling coefficient decreases, the refrigeration unit energy consumption increases; from low load to high load conditions (amplitude greater than 20%), the evaporator load demand increase Large, as the refrigerant mass flow increases, the actual amount of liquid in the evaporator in a short time is smaller than that required for the evaporator load, the superheat of the suction increases, the cooling capacity decreases, the refrigeration coefficient decreases, and the energy consumption of the refrigeration unit increases In the case of high load to low load (amplitude> 20%), the load on the evaporator decreases. Due to the decrease of the mass flow rate of the refrigerant, the actual amount of liquid stored in the evaporator in a short period of time is smaller than that required for the evaporator load A large amount of suction superheat reduction, Starting from wet compression, the extreme case of a sudden shutdown of the unit at full load reduces the load on the evaporator by 75%. As the mass flow of refrigerant suddenly decreases by 75%, the actual amount of liquid stored in the evaporator for a short period of time is less than that required for the evaporator load Large 55%, inspiratory superheating rapidly reduced, thereby reducing the exhaust superheat, oil effect decreased, and even lead to the compressor fuel. Although the first two orifice plate can be automatically adjusted in a certain range, but it is to deal with variable working conditions, variable load capacity is poor, and the cooling coefficient decreases, the cooling device energy consumption increases, generally unfit for use. 2.3 Thermal expansion valve Thermal expansion valve is widely used in central air conditioning chillers. It can control the evaporator liquid supply, but also throttling saturated liquid refrigerant. According to the different structure of the thermal expansion valve, divided into two types of internal and external balance. Taking into account the refrigerant flow through the evaporator to produce a certain pressure loss, in order to reduce the opening superheat and improve the evaporator heat transfer area utilization, generally from the expansion valve outlet to the evaporator outlet, the refrigerant pressure drop corresponding evaporation temperature Drop more than 2 ~ 3 ℃, should be used outside the balance of thermal expansion valve. External balanced thermal expansion valve works on the basis of force balance. At work, the upper part of the flexible metal diaphragm is affected by the pressure P3 of the working medium in the temperature-sensing package, and is affected by the outlet pressure P1 of the evaporator and the spring force P2 below. Diaphragm in the three force, up or down bulge, so that the valve hole off or open large, to adjust the amount of liquid supply for the evaporator. When the amount of liquid entering the evaporator is less than the heat load of the evaporator, the superheat of the vapor at the evaporator outlet increases and the pressure above the diaphragm is greater than the pressure below, thus forcing the diaphragm to bulge downward, Compression spring, and the valve needle top open, the valve hole open large, the amount of liquid for increased. Conversely when the liquid supply is greater than the evaporator heat load needs, then the outlet of the superheat steam decreases, the temperature of the system pressure decreases, the force above the diaphragm is less than the force below the diaphragm up the drum Out, the spring elongation, the plunger up and make the valve clearance is small, the amount of liquid on the evaporator will also be reduced. Thermal expansion valve overheating by the opening superheat and effective superheat composition, open overheating and spring preload, the effective degree of superheat and the spring and the valve stem stroke related. Expansion valve spring is designed according to standard conditions, the unit under standard conditions, the unit at full load or variable load operation are to maintain a high COP value. However, in the case of large differential pressure, the evaporation pressure is reduced and the liquid volume required for the evaporator load is reduced. However, in reality, the outlet pressure P1 of the evaporator decreases correspondingly as the evaporation pressure decreases due to the same degree of superheating, , The diaphragm pressure increases, the main valve opening increases, for liquid volume increased; but in the case of small pressure, the evaporation pressure increases, the evaporator load demand increased the amount of liquid, Inspiratory overheating constant case, due to the evaporation pressure increases, the evaporator outlet pressure P1 corresponding increase in diaphragm pressure drop smaller, so that the main valve opening decreases, reducing the amount of liquid supply; under variable load in this way. Therefore, thermal expansion valve in variable conditions for liquid volume adjustment needs to be further improved. Schematic diagram of a thermal expansion valve shown in Figure 1: Figure 1 Schematic diagram of the thermal expansion valve 2.4 Float + main throttle float + The main throttle valve is used for a free liquid evaporator, such as horizontal full Liquid evaporator automatically adjust the amount of liquid supply. Through the regulation of the float valve, a substantially constant liquid level can be maintained in the evaporator. The float valve has a cast iron housing, the liquid connection pipe and the gas connection pipe are respectively connected with the liquid and vapor of the controlled evaporator, so that the liquid level of the float valve housing is consistent with the liquid level in the evaporator. When the liquid level in the evaporator decreases, the liquid level in the housing also decreases. When the float falls, the valve needle opens the orifice to increase the liquid level of the float valve, and the valve spool The upper pressure P4 decreases and the pressure Ps at the upper part of the main expansion valve (including the spring force P5 at the upper part of the main expansion valve and the pressure P4 at the outlet of the float valve) decreases. When the pressure P1 at the lower part of the main expansion valve is larger than Ps, The main spool moves upward, increasing the opening of the valve, the main expansion valve for liquid volume increases; the other hand, the main expansion valve to reduce the amount of liquid supply. Float valve liquid volume and the main expansion valve core pressure drop (ΔP = P1-Ps) form a proportional relationship, adjust the size of the liquid volume, when the liquid level in the shell rises to the upper limit of the float, the valve needle hole Mouth close, Ps> P1, the main expansion valve is closed and stop the liquid, then the evaporator level is no longer rising, which can prevent the evaporation of liquid level is too high to cause wet compression, but also to ensure that the evaporator liquid supply and evaporation load Match. Since the upper part of the main expansion valve spring is designed according to standard conditions, the unit maintains a high COP at full load or variable load under standard conditions. However, in the case of small pressure drop, the condensing pressure is reduced and P1 is decreased. P1 is slightly smaller than the spring force in the upper part of the valve core, so that the opening degree of the main valve is small and the amount of liquid supply is too small, resulting in the required evaporation level A lag time, the system cooling coefficient decreases, the cooling device energy consumption increases, the same under variable load. Float + the main throttle valve in variable conditions for liquid volume adjustment needs to be further improved. Float + main throttle schematic diagram shown in Figure 2: Figure 2 Float + main throttle schematic diagram 3. Electronic expansion valve working principle and control 3.1 Electronic expansion valve - suction superheat control suction Gas overheating control system consists of electronic expansion valve, pressure sensor, temperature sensor, controller, work, the pressure sensor outlet pressure of the evaporator P1, the temperature sensor overheating compressor suction to the controller, the controller will signal After processing, the output command is then applied to the stepping motor of the electronic expansion main valve and the valve is opened to the desired position. To maintain the amount of fluid required for the evaporator. The electronic expansion valve stepping motor is based on the evaporator outlet pressure P1 changes, the compressor suction superheat changes in real-time output changes in power, the real-time output changes in the power to overcome various conditions in time and the main expansion under various load conditions Valve spring force changes, the valve opening to meet the needs of the evaporator liquid supply, and then the evaporator liquid supply can be real-time and evaporating load matching, that electronic expansion valve can be set manually by the controller, effective control Overheating. In addition, the electronic expansion valve from fully closed to fully open state of its use only takes a few seconds, the reaction and the speed of action, opening and closing characteristics and speed can be artificially set; electronic expansion valve in the 10% - 100% range Within the precise adjustment, and the adjustment range can be set according to the characteristics of different products. Selection of electronic expansion valve - suction superheat control, the unit regardless of standard conditions, changing conditions, full load, variable load operation to maintain a high COP level. Electronic expansion valve - suction superheat control refrigeration system diagram shown in Figure 3: Figure 3 electronic expansion valve - suction superheat control cooling system diagram 3.2 electronic expansion valve - liquid level control level control system by Electronic expansion valve, liquid level sensor, liquid level controller. When the liquid level in the evaporator changes up and down, the liquid level sensor in the evaporator changes the proportional relationship of the liquid level with a 4-20mA signal to the liquid level controller. After the liquid level controller processes the signal and then outputs the command Stepper motor in the electronic expansion of the main valve, so that the opening increased, reduced, in order to maintain the refrigerant level within a limited range. The electronic expansion valve stepping motor is based on changes in the level of refrigerant output changes in real-time power, the real-time output changes in the power to overcome the various conditions in time and under various load changes in the main expansion valve spring force, so that the valve Opening to meet the needs of the evaporator for liquid volume, and then the evaporator liquid volume can be matched with the evaporation load in real time, that electronic expansion valve can be set manually by the controller to effectively control the evaporation level. Select electronic expansion valve - liquid level control, the unit regardless of standard conditions, variable conditions, full load, variable load operation are maintained at a high COP level. Electronic expansion valve - liquid level control is generally used in the suction superheat less than 2 ℃ cooling device, and electronic expansion valve - suction superheat is generally used in suction superheat 5 ℃ refrigeration device, so the former ratio The latter is more efficient use of evaporation area, increase evaporation load, get a higher COP value. Electronic expansion valve - liquid level control refrigeration system diagram shown in Figure 4: Figure 4 electronic expansion valve - liquid level control refrigeration system diagram 4. Conclusion throttle mechanism in order to save energy, should be in different conditions, different Under load to ensure that the amount of liquid supply to the evaporator and the evaporation load to match. Way to save energy is the timely control of superheat (control level), real-time effective regulation of flow. Electronic expansion valve in superheat control (level control), flow regulation are better than the traditional throttling mechanism, and the reaction faster, wider range of adjustment, energy saving effect is more significant, has broad application prospects.