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Do you understand the classification and selection of pneumatic actuators?


Release time:

2022-06-14

今日,由无锡鑫明自控阀业有限公司为您具体介绍一下气动执行器的分类与选型?       气动执行器的分类      1.薄膜式执行机构      气动薄膜式执行机构的信号压力p效果于膜片,使其变形,带动膜片上的推杆移动,使阀芯发生位移,然后改变阀的开度。它结构简略,价格便宜,维修方便,广泛应用。气动薄膜执行机构有正效果和反效果两种方式。      当来自操控器或阀门定位器的信号压力加大时,阀杆向下的动作的叫正效果执行机构;当信号压力加大时,阀杆向上动作的叫反效果执行机构。正效果执行机构的信号压力是通入波纹膜片上方的薄膜气室;反效果执行机构的信号压力是通入波纹膜片下方的薄膜气室。经过替换个别零件,两者就能相互改装。      2.活塞式执行机构      气动活塞执行机构使活塞在气缸中移动发生推力,明显,活塞式的输出力度远大于薄膜式。因而,薄膜式适用于出力较小、精度较高的场合;活塞式适用于输出力较大的场合,如大口径、高压降操控或蝶阀的推进设备。除薄膜式和活塞式之外,还有一种长行程执行机构,它的行程长,转矩大,适用于输出角位移和大力矩的场合。      气动活塞执行机构的主要部件为气缸、活塞、推杆。气缸内活塞随气缸内两边压差的改变而移动。依据特性分为比例式和两位式两种。两位式依据依据输入活塞两边操作压力的巨细,活塞从高压侧被推向低压侧。比例式是在两位式基础上加以阀门定位器,使推杆位移和信号压力成比例关系。      3.齿轮齿条式执行机构      所有配件都选用的防腐蚀处理技术,能适应各种恶劣工况。其高低温以及各种特别行程的执行器在各种应用领域都有良好的表现。      气动执行器的分类四气动执行器的选型      在选用气动执行器前,请确认阀门扭矩。并在扭矩上添加安全值,水蒸汽或非光滑液体介质添加百分之25安全值;非光滑浆料液体介质添加白分之30安全值。      当选用阀门扭矩为210NM,气源压力只要5bar,介质为非光滑的水蒸汽,考虑到安全因素,添加百分之25安全值值即262NM,按双效果输出扭矩表查找气源压力在5bar时相应扭矩值。应选用277NM,型号为POADA300。      五气动执行器的性能特点      1.气动设备额外输出力或力矩应符合GB/T12222和GB/T12223的规则上面为薄膜式执行机构;      2.在空载情况下,对气缸内输入按规则的气压,其动作应平稳,无卡阻及爬行现象;      3.在0.6MPa的空气压力下,气动设备启、闭两个方向的输出力矩或推力,其值应不小于气动设备标牌所标示的数值,且动作应灵敏,不允许各部位出现永jiu变形及其他异常现象;      4.密封实验用大工作压力进行实验时,从各自背压一侧泄漏出的空气量不允许超越(3+0.15D)cm3/min(标准状态);从端盖、输出轴处泄漏出的空气量不允许超越(3+0.15d)cm3/min;      5.强度实验用1.5倍的大工作压力进行实验,保持实验压力3min后,其缸体端盖和静密封部位不允许有渗漏及结构变形;      6.动作寿数次数,气动设备模拟气动阀门动作,在保持两个方向的输出力矩或推力能力的情况下,启闭操作的启闭次数应不低于50000次(启—闭循环为一次);      7.带缓冲机构的气动设备,当活塞运动到行程终端方位时,不允许出现冲击现象。           上述就是由无锡鑫明自控阀业有限公司为您具体介绍的关于气动执行器分类与选型的全部内容,如有任何疑问,欢迎随时前来咨询!

Do you understand the classification and selection of pneumatic actuators?

Today, Wuxi Xinming automatic control valve industry Co., Ltd. will give you a specific introduction.Pneumatic actuatorClassification and selection?
     Pneumatic actuatorClassification


1. Membrane type actuator
The signal pressure p of the pneumatic diaphragm actuator has an effect on the diaphragm, deforms it, drives the push rod on the diaphragm to move, displaces the valve core, and then changes the opening of the valve. It has the advantages of simple structure, low price, convenient maintenance and wide application. Pneumatic membrane actuators have positive effects and negative effects in two ways.
When the signal pressure from the controller or valve positioner increases, the downward action of the valve stem is called the positive effect actuator; when the signal pressure increases, the upward action of the valve stem is called the negative effect actuator. The signal pressure of the positive effect actuator is passed into the film air chamber above the corrugated diaphragm; the signal pressure of the counter effect actuator is passed into the film air chamber below the corrugated diaphragm. After replacing individual parts, the two can be modified with each other.
2. Piston type actuator
The pneumatic piston actuator causes the piston to move in the cylinder to generate thrust. Obviously, the output strength of the piston type is much greater than that of the thin film type. Therefore, the diaphragm type is suitable for occasions with small output and high precision; the piston type is suitable for occasions with large output force, such as large diameter, high pressure drop control or butterfly valve propulsion equipment. In addition to the film type and piston type, there is also a long stroke actuator, which has a long stroke and large torque, and is suitable for occasions with output angular displacement and large torque.
The main components of pneumatic piston actuator are cylinder, piston and push rod. The piston in the cylinder moves with the pressure difference between the two sides of the cylinder. According to the characteristics, it is divided into two types: proportional type and two-bit type. According to the size of the operating pressure on both sides of the input piston, the piston is pushed from the high pressure side to the low pressure side. Proportional type is based on the two-bit valve positioner, so that the displacement of the push rod and the signal pressure are proportional to each other.
3. Rand-pinion actuator
All accessories are selected anti-corrosion treatment technology, can adapt to a variety of harsh conditions. Its high and low temperature and various special stroke actuators have good performance in various application fields.
Pneumatic actuator classification four pneumatic actuator selection
Before selecting a pneumatic actuator, confirm the valve torque. And in the torque to add a safety value, water vapor or non-smooth liquid medium to add 25 percent of the safety value; non-smooth slurry liquid medium to add 30 percent of the safety value of white.
The selected valve torque is 210NM, the air source pressure is only 5bar, and the medium is non-smooth water vapor. Considering the safety factor, add 25% of the safety value, namely 262NM, and find the corresponding torque value when the air source pressure is 5bar according to the double-effect output torque table. Should be selected 277NM, model POADA300.
Performance characteristics of five pneumatic actuators
1. The additional output force or torque of pneumatic equipment shall comply with the rules of GB/T12222 and GB/T12223, which are membrane type actuators;
2. In the case of no-load, enter the air pressure according to the rules in the cylinder, and its action should be stable, without blocking and crawling;
3. Under the air pressure of 0.6MPa, the output torque or thrust of pneumatic equipment in the opening and closing directions shall not be less than the value marked on the sign of pneumatic equipment, and the action shall be sensitive, and permanent jiu deformation and other abnormal phenomena shall not occur in each part;
4. When the sealing experiment is carried out with large working pressure, the amount of air leaked from the respective back pressure side is not allowed to exceed (3 0.15D)cm3/min (standard state); The amount of air leaked from the end cover and output shaft is not allowed to exceed (3 0.15d)cm3/min;
5. The strength test is carried out with a large working pressure of 1.5 times. After maintaining the experimental pressure for 3min, the cylinder end cover and static seal parts are not allowed to have leakage and structural deformation;
6. The number of operating life, pneumatic equipment to simulate the action of pneumatic valves, in the case of maintaining the output torque or thrust capacity in both directions, the number of opening and closing operations should not be less than 50000 (opening-closing cycle is once);
7. Pneumatic equipment with buffer mechanism, when the piston moves to the end of the stroke, no impact is allowed.
    



















The above is all about the classification and selection of pneumatic actuators specifically introduced by Wuxi Xinming automatic control valve industry Co., Ltd., if you have any questions, please feel free to come to consult!