机械手-多用途气动机器人结构设计
机械手-多用途气动机器人结构设计,机械手,多用途,气动,机器人,结构设计
多用途气动机器人结构设计摘要 本文简要介绍了工业机器人的概念,机械手硬件和软件的组成,即PLC控制的气动机械手的系统工作原理,机械手各个部件的整体尺寸设计,气动技术的特点,PLC控制的特点。本文对机械手进行总体方案设计,确定了机械手的坐标形式和自由度,确定了机械手的技术参数。同时,设计了机械手的夹持式手部结构,设计了机械手的手腕结构,计算出了手腕转动时所需的驱动力矩和回转气缸的驱动力矩。设计了机械手的手臂结构。设计出了机械手的气动系统,绘制了机械手气压系统工作原理图,大大提高了绘图效率和图纸质量。利用可编程序控制器对机械手进行控制,选取了合适的PLC型号,根据机械手的工作流程制定了可编程序控制器的控制方案,画出了机械手的工作时序图,并绘制了可编程序控制器的控制程序。关键词: 工业机器人 机械手 气动 可编程序控制器(PLC)Structural Design of Multi-purpose Pneumatic RobotAbstract At first, the paper introduces the conception of the industrial robot and the Eller. Dairy information of the development briefly. Whats more, the paper accounts for the background and the primary mission of the topic. The paper introduces the function, composing and classification of the manipulator, tells out the free-degree and the form of coordinate. At the same time, the paper gives out the primary specification parameter of this manipulator,The paper designs the structure of the hand and the equipment of the drive of the manipulator. This paper designs the structure of the wrist, computes the needed moment of the drive when the wrist wheels and the moment of the drive of the pump.The paper designs the structure of the arm.The paper designs the system of air pressure drive and draws the work principle chart, the manipulator uses PLC to control. The paper institutes two control schemes of PLC according to the work flow of the manipulator. The paper draws out the work time sequence chart and the trapezium chart. Whats more, the paper workout the control program of the PLC, KEY WORDS: industrial robot manipulator pump air pressure drive PLC目 录第一章 引言 1.1机械手概述. .11.2气动机械手的设计要求21.3机械手的系统工作原理及组成.2第二章 机械手的整体设计方案2.1机械手的座标型式与自由度 62.2机械手的手部结构方案设计 72.3机械手的手腕结构方案设计72.4机械手的手臂结构方案设计72.5机械手的驱动方案设计72.6机械手的控制方案设计8 2.7机械手的主要技术参数8第三章 手部结构设计3.1夹持式手部结构10 3.1.1手指的形状和分类3.1.2设计时考虑的几个问题3.1.3手部夹紧气缸的设计第四章 手腕结构设计4.1手腕的自由度144.2手腕的驱动力矩的计算144.2.1手腕转动时所需的驱动力矩4.2.2回转气缸的驱动力矩计算4.2.3回转气缸的驱动力矩计算校核第五章 手臂伸缩,升降,回转气缸的设计与校核5.1手臂伸缩部分尺寸设计与校核205.1.1尺寸设计5.1.2尺寸校核5 .1 .3导向装置5 .1 .4平衡装置5.2手臂升降部分尺寸设计与校核215.2.1尺寸设计5.2.2尺寸校核5.3手臂回转部分尺寸设计与校核235.3.1尺寸设计5.3.2尺寸校核第六章 气动系统设计6.1气压传动系统工作原理图及元器件的选择25第七章 机械手的PLC控制系统设计7.1可编程序控制器的选择及工作过程267.1.1可编程序控制器的选择7.1.2可编程序控制器的工作过程7.2可编程序控制器的使用步骤277.3机械手可编程序控制器控制方案28 7.3.1控制系统的工作原理及控制要求 7.3.2 气动机械手的工作流程 7.3.3 I/0分配 7.3.4梯形图设计第八章 结论36致谢37参考文献38III毕 业 设 计 任 务 书 2008 年 3 月 3 日 毕业设计题目多用途气动机器人结构设计指导教师俞云强职称副教授专业名称机电一体化技术班级机电50532学生姓名孙启亮学号5020053223设计要求内容包括 :1、第一章为引言; 2、第二章为本选题总体设计方面的论述; 3、从第三章起为毕业设计总体设计框架和设计过程的详细论述; 4、倒数第二章为毕业设计的结果和讨论; 5、最后一章为展望与总结。完成毕业课题的计划安排序号内容时间安排1外文资料翻译2008-2-20至2008-3-32搜集课题相关资料2008-3-4至2008-3-143完成毕业设计说明书2008-3-15至2008-3-314预审,修改2008-4-1至2008-4-115答辩2008-4-20答辩提交资料外文资料翻译,毕业设计说明书计划答辩时间2008-4-20 无锡职业技术学院机电技术学院 2008 年 3 月 3日外文资料翻译Rotary pumps These are built in many different designs and are extremely popular in modern fluid-power system. The most common rotary-pump designs used today are spur-gear, generated-rotary , sliding-vane ,and screw pump ,each type has advantages that make it the most suitable for a given application .Spur-gear pumps. these pumps have two mating gears are turned in a closely fitted casing. Rotation of one gear ,the driver causes the second ,or follower gear, to turn . the driving shaft is usually connected to the upper gear of the pump .When the pump is first started ,rotation of gears forces air out the casing and into the discharge pipe. this removal of air from the pump casing produces a partial vacuum on the pump inlet ,here the fluid is trapped between the teeth of the upper and lower gears and the pump casing .continued rotation of the gears forces the fluid out of the pump discharge .Pressure rise in a spur-gear pump is produced by the squeezing action on the fluid ad it is expelled from between the meshing gear teeth and casing ,.a vacuum is formed in the cavity between the teeth ad unmesh, causing more fluid to be drawn into the pump ,a spur-gear pump is a constant-displacement unit ,its discharge is constant at a given shaft speed. the only way the quantity of fluid discharge by a spur-gear pump of type in figure can be regulated is by varying the shaft speed .modern gear pumps used in fluid-power systems develop pressures up to about 3000psi.Figure shows the typical characteristic curves of a spur-gear rotary pump. These curves show the capacity and power input for a spur-gear pump at various speeds. At any given speed the capacity characteristic is nearly a flat line the slight decrease in capacity with rise in discharge pressure is caused by increased leakage across the gears from the discharge to the suction side of the pump. leakage in gear pumps is sometimes termed slip. Slip also increase with arise pump discharge pressure .the curve showing the relation between pump discharge pressure and pump capacity is often termed the head-capacity or HQ curve .the relation between power input and pump capacity is the power-capacity or PQ curve .Power input to a squr-gear pump increases with both the operating speed and discharge pressure .as the speed of a gear pump is increased. Its discharge rate in gallons per minute also rise . thus the horsepower input at a discharge pressure of 120psi is 5hp at 200rpm and about 13hp at 600rpm.the corresponding capacities at these speed and pressure are 40 and 95gpm respectively, read on the 120psi ordinate where it crosses the 200-and 600-rpm HQ curves .Figure is based on spur-gear handing a fluid of constant viscosity , as the viscosity of the fluid handle increases (i.e. ,the fluid becomes thicker and has more resistance to flow ),the capacity of a gear pump decreases , thick ,viscous fluids may limit pump capacity t higher speeds because the fluid cannot into the casing rapidly enough fill it completely .figure shows the effect lf increased fluid biscosity on the performance of rotary pump in fluid-power system .at 80-psi discharge pressure the pp has a capacity lf 220gpm when handling fluid of 100SSU viscosity lf 500SSU . the power input to the pump also rises ,as shown by the power characteristics.Capacity lf rotary pump is often expressed in gallons per revolution of the gear or other internal element .if the outlet of a positive-displacement rotary pump is completely closed, the discharge pressure will increase to the point where the pump driving motor stalls or some part of the pump casing or discharge pipe ruptures .because this danger of rupture exists systems are filled with a pressure relief valve. This relief valve may be built as of the pump or it may be mounted in the discharge piping.Sliding-Vane PumpsThese pumps have a number of vanes which are free to slide into or out of slots in the pup rotor . when the rotor is turned by the pump driver , centrifugal force , springs , or pressurized fluid causes the vanes to move outward in their slots and bear against the inner bore of the pump casing or against a cam ring . as the rotor revolves , fluid flows in between the vanes when they pass the suction port. This fluid is carried around the pump casing until the discharge port is reached. Here the fluid is forced out of the casing and into the discharge pipe.In the sliding-vane pump in Figure the vanes in an oval-shaped bore. Centrifugal force starts the vanes out of their slots when the rotor begins turning. The vanes are held out by pressure which is bled into the cavities behind the vanes from a distributing ring at the end of the vane slots. Suction is through two ports A and AI, placed diametrically opposite each other. Two discharge ports are similarly placed. This arrangement of ports keeps the rotor in hydraulic balance, reliving the bearing of heavy loads. When the rotor turns counterclockwise, fluid from the suction pipe comes into ports A and AI is trapped between the vanes, and is carried around and discharged through ports B and BI. Pumps of this design are built for pressures up to 2500 psi. earlier models required staging to attain pressures approximating those currently available in one stage. Valving , uses to equalize flow and pressure loads as rotor sets are operated in series to attain high pressures. Speed of rotation is usually limited to less than 2500rpm because of centrifugal forces and subsequent wear at the contact point of vanes against the cam-ring surface. Two vanes may be used in each slot to control the force against the interior of the casing or the cam ring. Dual vanes also provide a tighter seal , reducing the leakage from the discharge side to the suction side of the pump . the opposed inlet and discharge port in this design provide hydraulic balance in the same way as the pump, both these pumps are constant-displacement units.The delivery or capacity of a vane-type pump in gallons per minute cannot be changed without changing the speed of rotation unless a special design is used. Figure shows a variable-capacity sliding-vane pump. It dose not use dual suction and discharge ports. The rotor rums in the pressure-chamber ring, which can be adjusted so that it is off-center to the rotor. As the degree of off-center or eccentricity is changed, a variable volume of fluid is discharged. Figure shows that the vanes create a vacuum so that oil enters through 180 of shaft rotation. Discharge also takes place through 180 of rotation. There is a slight overlapping of the beginning of the fluid intake function and the beginning of the fluid discharge.Figure shows how maximum flow is available at minimum working pressure. As the pressure rises, flow diminishes in a predetermined pattern. As the flow decreases to a minimum valve, the pressure increases to the maximum. The pump delivers only that fluid needed to replace clearance floes resulting from the usual slide fit in circuit components.A relief valve is not essential with a variable-displacement-type pump of this design to protect pumping mechanism. Other conditions within the circuit may dictate the use of a safety or relief valve to prevent localized pressure buildup beyond the usual working levels.For automatic control of the discharge , an adjustable spring-loaded governor is used . this governor is arranged so that the pump discharge acts on a piston or inner surface of the ring whose movement is opposed by the spring . if the pump discharge pressure rises above that for which the by governor spring is set , the spring is compressed. This allows the pressure-chamber ring to move and take a position that is less off center with respect to the rotor. The pump theb delivers less fluid, and the pressure is established at the desired level. The discharge pressure for units of this design varies between 100 and 2500psi.The characteristics of a variable-displacement-pump compensator are shown in figure. Horsepower input values also shown so that the power input requirements can be accurately computed. Variable-volume vane pumps are capacity of multiple-pressure levels in a predetermined pattern. Two-pressure pump controls can provide an efficient method of unloading a circuit and still hold sufficient pressure available for pilot circuits.The black area of the graph of figure shows a variable-volume pump maintaining a pressure of 100psi against a closed circuit. Wasted power is the result of pumping oil at 100psi through an unloading or relief valve to maintain a source of positive pilot pressure. Two-pressure type controls include hydraulic, pilot-operated types and solenoid-controlled, pilot-operated types. The pilot oil obtained from the pump discharge cannot assist the governor spring. Minimum pressure will result. The plus figure shows the solenoid energized so that pilot oil assists compensator spring. The amount of assistance is determined by the small ball and spring, acting as a simple relief valve. This provides the predetermined maximum operating pressure.Another type of two-pressure system employs what is termed a differential unloading governor. It is applied in a high-low or two-pump circuit. The governor automatically, Through pressure sensing, unloads the large volume pump to a minimum deadhead pressure setting. Deadhead pressure refers to a specific pressure level established as resulting action of the variable-displacement-pump control mechanism. The pumping action and the resulting flow at deadhead condition are equal to the leakage in the system and pilot-control flow requirements. No major power movement occurs at this time, even though the hydraulic system may be providing a clamping or holding action while the pump is in deadhead position The governor is basically a hydraulically operated, two-pressure control with a differential piston that allows complete unloading when sufficient external pilot pressure is applied to pilot unload port.The minimum deadhead pressure setting is controlled by the main governor spring A. the maximum pressure is controlled by the relief-valve adjustment B. the operating pressure for the governor is generated by the large-volume pump and enters through orifice C. To use this device let us assume that the circuit require a maximum pressure of 1000psi, which will be supplied by a 5-gpm pump. It also needs a large flow (40gpm) at pressure up to 500psi; it continues to 1000pso at the reduced flow rate. A two-pump system with an unloading governor on the 40-gpm pump at 500psi to a minimum pressure setting of 200psi (or another desired value) , which the 5-gpm pump takes the circuit up to1000psi or more.Note in figure that two sources of pilot pressure are required. One ,the 40-gpm pump, provides pressure within the housing so that maximum pressure setting can be obtained. The setting of the spring, plus the pressure within the governor housing, determines the maximum pressure capacity of the 40-gpm pump. The second pilot source is the circuit proper, which will go to 1000psi. this pilot line enters the governor through orifice D and acts on the unloading piston E . the area of piston E is 15 percent greater than the effective area of the relief poppet F. the governor will unload at 500psi and be activated at 15percent below 500psi, or 425psi. By unloading, we mean zero flow output of the 40-gpm pump.As pressure in the circuit increases from zero to 500psi, the pressure within the governor housing also increases until the relief-valve setting is reached, at which time the relief valve cracks open, allowing flow to the tank.The pressure drop in the hosing is a maximum additive value, allowing the pump to deadhead. Meanwhile, the system pressure continues to rise above 700psi, resulting in a greater force on the bottom of piston E than on the top. The piston then completely unseats poppet F, which results in a further pressure drop within the governor horsing to zero pressure because of the full-open position of the relief poppet F. flow entering the housing through orifice is directed to the tank pass the relief poppet without increasing the pressure in housing. The deadhead pressure of the 40-gpm pump then decreases to the lower set value. Thus , at the flow rate to the unloading governor ,the 40gpm pump goes to deadhead. The flow rate to the circuit decreases to 5gpm as the pressure to 1000psi, the 5-gpm pump is also at its deadhead setting, thus only holding system pressure.The 4-gpm pump unloads its volume at 500psi. It requires a system pressure of 600psi to unload the 40-gpm pump to its minimum pressure of 200psi. the 600-psi pilot supply enters through orifice D and acts on the differential piston E. The pumps volume is reduced to zero circuit-flow output at 500psi. The additional 100-psi pilot pressure is required to open poppet F completely and allow the pressure within the housing to decrease to zero.As circuit pressure decreases ,both pumps come back into service in a similar pattern.- 6 -
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