簡易插床及液壓系統(tǒng)設(shè)計(jì)【含SW三維及4張CAD圖】

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What is hydraulic?Hydraulic systems are power-transmitting assemblies employing pressurized liquid to transmit energy from an energy-generating source to an energy-use area. All hydraulic systems depend on Pascal’s law, named after Blaise Pascal, who discovered the law. This law states that pressurized fluid within a closed container-such as cylinder or pipe-exerts equal force on all of the surfaces of the container.In actual hydraulic systems, Pascal’s law defines the basis of the results which are obtained from the system. Thus, a pump moves the liquid in the system. The intake of the pumps connected to a liquid source, usually called the tank or reservoir. Atmospheric pressure, pressing on the liquid in the reservoir, forces the liquid into the pump. When the pump operates, it forces liquid from the tank into the discharge pipe at a suitable pressure.The flow of the pressurized liquid discharged by the pump is controlled by valves. Three control functions are used in most hydraulic systems: (1) control of the liquid pressure, (2) control of the liquid flow rate, and (3) control of the direction of flow of the liquid.The liquid discharged by the pump in a fluid-power system is directed by valves to a hydraulic motor. A hydraulic motor develops rotary force and motion, using the pressurized liquid as its energy source. Many hydraulic motors are similar to pumps, except that the motor operates in a reverse manner from a pump.Where linear instead of rotary motion is desired, a cylindrical tube fitted with a movable piston, called a hydraulic cylinder, is often used. When the piston is moved by the pressurized fluid, the piston rod imparts a force or moves an object through a desired distance.Restricting the movement of the piston in a hydraulic cylinder, as when the piston carries a load, creates a specific pressure relationship within the cylinder. The surface area of the piston face is said to contain a specific number of square inches. The pressure of the pressurized liquid, multiplied by the piton area, produces an output force, measured in pound, at the end of the piston rod.The speed of movement of the piston rod depends on how fast the pressurized fluid enters the cylinder. Flow into the cylinder can be directed to either end, producing either a pushing or pulling force at the piston rod end. A seal around the rod where it passes through the cylinder end prevents leakage of the liquid.Directional control of the piston depends on which end of cylinder the liquid enters. As pressurized liquid enters one end of the cylinder, liquid must be drained from the other end. The drained liquid is led back to the reservoir. In a pneumatic system using air, the air in the exhausting end of the cylinder is vented to the atmosphere.Directional-control valves, also called two-way, three-way, four-way, etc. , are named in accordance with their basic function. Pressure-control and simple restrictor valves are usually two-way valves. They provide ON or OFF service. A three-way valves may perform several functions, all associated with the three-ports in the valve. For example, the power or pressurized liquid from a pump in a tractor may be sent to the hydraulic system serving the tractor’s front-end loader. Or the three-way valve may send the pressurized liquid to a hydraulic motor driving a feed conveyor while the front-end loader is not being used.Three-way valves may also be used to direct pressurized fluid to a single-acting hydraulic cylinder. As the three-way valve is actuated (operated) it can stop the pressurized flow to the cylinder. Further, the same valve can divert liquid from the cylinder to the reservoir, so the cylinder can retract by gravity or return springs and assume its original position. 什么是液壓？液壓系統(tǒng)是利用液體為介質(zhì)把能量從動(dòng)力源傳遞到消耗位置的動(dòng)力傳遞系統(tǒng)。所有液壓系統(tǒng)原理都基于帕斯卡定律，是以發(fā)現(xiàn)這個(gè)定律的帕斯卡的名字而命名的。這個(gè)定律表明在一個(gè)密封的容器里，如缸體或管子，受壓液體向容器表面所有方向施加相等的力。在實(shí)際液壓系統(tǒng)中，帕斯卡定律解釋從系統(tǒng)中得到的各種結(jié)果。泵使流體在系統(tǒng)里流動(dòng)。泵的吸入口接到液壓油容器，通常稱為液壓油箱。大氣壓壓在油箱里液體上，使液體流入泵里。當(dāng)液壓泵工作時(shí)，它以適當(dāng)?shù)膲毫Π岩后w從油箱壓到管道里。泵排出的高壓液體由閥控制。多數(shù)液壓系統(tǒng)運(yùn)用三種控制方式：（1）流體壓力控制；（2）流體速度控制；（3）流體方向控制。在液壓系統(tǒng)中由泵排出的液體經(jīng)由控制閥到液壓馬達(dá)。液壓馬達(dá)利用受壓的流體作為它的能量源產(chǎn)生旋轉(zhuǎn)的力和運(yùn)動(dòng)。液壓馬達(dá)跟泵的結(jié)構(gòu)類似，只不過它的工作原理是相反的。在要求直線運(yùn)動(dòng)代替旋轉(zhuǎn)運(yùn)動(dòng)的地方是用液壓缸，它由運(yùn)動(dòng)活塞和缸體構(gòu)成。當(dāng)活塞由高壓流體驅(qū)動(dòng)時(shí)，活塞桿傳遞力，推動(dòng)負(fù)載移動(dòng)一段設(shè)定的距離。當(dāng)液壓缸中的活塞運(yùn)動(dòng)受阻時(shí)，例如當(dāng)活塞有負(fù)載，在液壓缸中必然會(huì)產(chǎn)生一個(gè)相應(yīng)的壓力?；钊娣e以平方英寸為單位，受壓液體的壓力乘以活塞面積，就等于在活塞桿的末端產(chǎn)生的一個(gè)以磅為單位的輸出力?；钊麠U的速度取決于受壓液體進(jìn)入液壓缸里的多少?？梢钥刂朴鸵毫魅缫簤焊椎钠渲幸欢耍诨钊麠U上產(chǎn)生一個(gè)拉力或產(chǎn)生一個(gè)推力。在活塞上有密封裝置，防止流體的泄漏。活塞的方向控制取決于流體進(jìn)入液壓缸的哪一端，當(dāng)高壓流體進(jìn)入液壓缸的一端時(shí)，流體一定從另一端流出。排出的流體又回液壓油箱。在利用空氣的氣動(dòng)系統(tǒng)里，空氣是由缸體排放入大氣中的。方向控制閥也稱作二通閥、三通閥和四通閥等等，是根據(jù)它們的基本功能命名的。壓力控制閥和簡單的節(jié)流閥，通常采用二通閥，他們僅有通和斷功能。三通閥可以有幾種功能,這些和三通閥的油口有關(guān)。例如，來自泵的高壓流體可能傳送到拖拉機(jī)的液壓系統(tǒng)里驅(qū)動(dòng)負(fù)載。在不需驅(qū)動(dòng)時(shí)，三通閥將高壓流體送到驅(qū)動(dòng)輸送機(jī)構(gòu)的液壓馬達(dá)上。也可以用三通閥來控制單作用式液壓缸（只能單方面施力）的運(yùn)動(dòng)。例如，當(dāng)三通閥通時(shí)，它可以阻止高壓流體流入液壓缸。同時(shí)，該閥可以把液壓缸中的液體導(dǎo)向液壓油箱，因此，柱塞缸可以在重力或回程彈簧的作用下回到它的初始位置。四通閥有四個(gè)油口。壓力油口控制流體連接到需要高壓的地方。同時(shí)有一個(gè)油口從高壓區(qū)排出油液。排出的液體流回液壓油箱。