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HYDRAULIC CYLINDER BASIC KNOWLEDGE! COMPREHENSIVE AND EASY TO UNDERSTAND!
HYDRAULIC CYLINDER BASIC KNOWLEDGE! COMPREHENSIVE AND EASY TO UNDERSTAND! With the development of modern industry, hydraulic transmission technology has been widely used and developed in many industries, such as construction machinery loaders, bulldozers and rollers, forklifts, belt conveyors and truck cranes Construction Machinery Pile driver, Hydraulic Jack and grader, etc. ; agricultural machinery, Automotive Industry, mining machinery, metallurgical machinery... hydraulic transmission equipment usually by power, execution, control and auxiliary components. And the hydraulic cylinder as to achieve linear reciprocating motion or less than 360. The hydraulic mechanism of reciprocating motion, which is simple in structure and reliable in operation, is also the most widely used main executive element in hydraulic system. It is the hydraulic pressure energy produced by driving the prime mover in the form of mechanical energy to the hydraulic pump, it can drive the load directly to and fro or less than 360. A device that converts the Mechanical Energy of a reciprocating swing. If we want to understand hydraulic cylinder, we must know the following basic knowledge. The classification and composition of hydraulic cylinders can be divided into four types: Piston cylinder, plunger cylinder, swing cylinder and special cylinder According to the rated pressure is divided into high and ultra-high pressure hydraulic cylinder, medium and high pressure hydraulic cylinder and medium and low pressure hydraulic cylinder... 1, cylinder: Cylinder Cylinder is the main hydraulic cylinder parts, it and cylinder head, Piston and other parts constitute a closed chamber, Promote Piston Movement. There are 8 types of cylinder structure in common use, which are usually selected according to the connection form between cylinder and end cover. Materials generally require sufficient strength and impact toughness, but also have good welding performance, so the commonly used materials are: 25,45, ZG200 ~ 400,1CR18NI9 and so on. Cylinder cylinder blanks are usually cold-drawn or hot-rolled seamless steel tubes, therefore, the process is usually quenching and tempering (to ensure the strength of the cylinder, so that it can withstand the oil pressure will not deformation and damage)→ honing or boring (to ensure the cylinder diameter roughness, roundness, cylindricity and straightness, so that the piston seal after a long-term reciprocating motion remains the same)→ turning (to ensure the cylinder full length and other design size requirements)→ drilling (to ensure the processing of oil outlet hole, to ensure the access to the oil)→ Pliers 2, cylinder head: The cylinder head is installed at both ends of the hydraulic cylinder, a tight oil cavity is formed with the cylinder barrel. There are usually welding, thread, bolt, key and tie rod and other kinds of connection, generally according to the working pressure, cylinder connection, the use of environmental factors such as selection. 3. Piston Rod: Piston Rod is the main component of hydraulic cylinder transmission force. Medium Carbon Steel (E. G. No. 45 steel) is the material of choice. When the oil cylinder is working, the Piston rod is subjected to thrust, tension or bending moment, and it is necessary to ensure its strength; and the Piston Rod often slides in the guide sleeve, the fit should be proper, too tight, the friction is great, too loose, it is easy to cause stagnation and unilateral wear, which requires proper Surface roughness, straightness and roundness. Therefore, the process of Piston Rod is usually roughing → conditioning → semi-finishing → quenching → pre-plating → chromium plating → post-plating → finishing. 4. Piston: Piston is the main component to convert hydraulic energy into mechanical energy. Its effective working area directly affects the force and speed of the hydraulic cylinder. There are many kinds of connection between Piston and Piston Rod, such as clasp type, shaft sleeve type and nut type. HIGH STRENGTH CAST IRON HT200 ~ 300 or nodular cast iron for Pistons Without Guide Rings; High Quality Carbon Steels # 20, # 35 and # 45 for Pistons with Guide Rings. 5. Guide sleeve: the Guide sleeve plays a guiding and supporting role on the Piston Rod. It requires high matching precision, small friction resistance, good wear resistance and can bear the pressure, bending force and impact vibration of the Piston Rod. There is a sealing device inside to ensure that the cylinder barrel is sealed with a rod cavity, and a dust ring on the outside to prevent impurities, dust and moisture from being carried to the sealing device and damaging the seal. The metal guide sleeve is usually made of bronze, gray iron, ductile iron and oxide cast iron with low friction coefficient and good wear resistance. The non-metal guide sleeve can be made of polytetrafluoroethylene and polychlorotrifluoroethylene. 6. Cushioning device: The Piston and the Piston Rod have great momentum when driven by hydraulic pressure. When they enter the end cap and the bottom of the cylinder, they will cause mechanical collision, resulting in great impact pressure and noise. The buffer is used to avoid this kind of collision. Its working principle is that the oil (all or part) in the low-pressure Chamber of the cylinder can convert kinetic energy into heat energy by throttling, and the heat energy is carried out by the circulating oil to the hydraulic cylinder. The structure of the buffer device is divided into constant throttle area buffer device and variable throttle type buffer device. The main parameters of the hydraulic cylinder the main parameters of the hydraulic cylinder include pressure, flow, size and specification, piston stroke, motion speed, push-pull force, efficiency and hydraulic cylinder power, etc. . 1. PRESSURE: Pressure is the pressure of the oil acting on the unit area. The Formula P F / A is the load acting on the piston divided by the effective working area of the Piston. From the above formula, the establishment of pressure value is caused by the presence of load. The greater the load on the effective working area of the same Piston, the greater the pressure required to overcome the load. In other words, if the effective working area of the Piston is fixed, the greater the oil pressure, the greater the force produced by the Piston. Usually we say that the rated pressure, is the hydraulic cylinder can be long-term work pressure. According to the rated pressure, the pressure classification of hydraulic cylinder is shown in the following table: the maximum allowable pressure per MPA refers to the limit pressure that the hydraulic cylinder can bear in an instant, while the pressure test pressure refers to the test pressure that the hydraulic cylinder must bear when checking its quality, most of these two types of pressure states provide for pressures less than or equal to 1.5 times the rated pressure. 2, Flow: Flow is the unit time through the cylinder cylinder effective cross-sectional area of the volume. Formula Q v / t va, where V represents the volume of oil consumed in a stroke of the hydraulic cylinder Piston, t represents the time required for a stroke of the Hydraulic Cylinder Piston, v represents the speed of the Piston Rod, and a represents the effective working area of the Piston. 3. Piston Travel: Piston travel refers to the distance traveled between the Poles during reciprocating piston movements. In general, after satisfying the stability requirements of the cylinder, the standard stroke similar to the actual working stroke is selected. 4. The speed of the Piston: The speed is the distance per unit time that the pressure oil pushes the Piston, which can be expressed as v Q / a. 5. Dimension Specification: The dimension specification mainly includes the inner and outer diameter of the cylinder, the diameter of the Piston, the diameter of the Piston Rod and the size of the cylinder head, required to provide the push-pull force as well as the stroke to calculate, design and check. Common problems of hydraulic cylinder and maintenance of hydraulic cylinder as a component, a working device, as with all mechanical equipment, in the course of long-term operation, it is inevitable that different degrees of wear, fatigue, corrosion, looseness, aging, deterioration and even damage will occur in the structural parts of the hydraulic cylinder, which will worsen the working performance and technical condition, and then directly cause the whole hydraulic equipment failure, or even failure. Therefore, it is very important to eliminate and maintain the common problems in the daily work of hydraulic cylinder. The dynamic development of hydraulic cylinder with the development and popularization of hydraulic technology and the expansion of application fields and occasions, the working performance, structure, use range, manufacturing precision, appearance, material, test method of hydraulic cylinder are constantly put forward new requirements, therefore constantly promoting the development and progress of hydraulic cylinder. The general trend is: 1, high pressure, miniaturization. High pressure is an effective way to reduce the radial size and weight of hydraulic cylinder, and to reduce the volume of hydraulic device. 2. New Material, lightweight. With the high pressure, miniaturization, the use of hydraulic cylinder environment test, new material, lightweight has become one of the solutions. 3. Novel structural recombination. In order to adapt to the expansion of the application range of hydraulic cylinder, various new structures of hydraulic cylinder appear constantly, such as automatic control hydraulic cylinder, self-lock hydraulic cylinder, cable hydraulic cylinder, peristaltic hydraulic cylinder and compound hydraulic cylinder. 4. High Performance, multi variety. 5. Energy Saving and corrosion resistance.