How Does A Pneumatic Cylinder Work?

Overview of cylinder

As the core component in the pneumatic system, the air cylinder plays an indispensable role in industrial automation, mechanical manufacturing, aerospace and other industries.

 It mainly completes the work by guiding the piston to perform linear reciprocating motion in the cylinder barrel, and various accessories can be installed to complete the clamping, translation, rotation and other work of the object.

Precise driving and positioning of mechanical parts can be realized by accurately controlling the air pressure change inside the cylinder, so as to meet the requirements under various complex working conditions.

Working principle of cylinder

The pneumatic cylinder converts the pressure energy of the compressed air into mechanical energy through pneumatic transmission, and then the driving mechanism realizes linear reciprocating motion, swinging or rotating motion.Therefore, it is also called compressed air cylinder.

 In simple terms, the internal structure of the pneumatic piston cylinder is similar to a syringe, with cylinder barrel, piston, piston rod and other structures. The difference is that the syringe empties the fluid in the syringe by input of external force, while the cylinder pushes the piston and piston rod by input of compressed air to output external force.

The cylinder can be divided into single-acting cylinderand double-acting cylinder according to different structures and working modes.

 The piston of the single-acting cylinder only supplies air on one side, pushes the piston by air pressure to produce thrust to stretch out, and returns by spring or dead weight.

The double-acting cylinder has air pressure on both sides of its piston, and the forward or backward movement is realized by controlling the change of air pressure on both sides.

Cylinder parts and structure

The main parts of the cylinder include:

◆ Barrel: the inner cylindrical hole of the cylinder block is the place where the piston moves.

◆ End cover: It includes the cylinder head and other possible end covers (such as the sealing cover at both ends of the cylinder block). It is used to close the cylinder and connect with other parts. The intake valve and exhaust valve are installed on it.

◆ Piston: the piston reciprocates in the cylinder under the action of compressed gas. The piston is provided with a sealing ring to prevent air leakage between the left and right ends when the piston is working.

Generally, wear rings are also provided to improve the guiding property of the piston, reduce the wear of the piston seal ring, reduce the friction resistance and extend the service life.

Some models also have a built-in magnet, which is used to cooperate with the magnetic switch outside the cylinder for position detection.

◆ Piston rod: the piston rod is connected to the actuator outside the piston and the cylinder to transfer the reciprocating motion of the piston and output mechanical energy.

◆ Seals: including O-ring, cover packing, cushion gasket and various sealing rings inside and outside the cylinder. Generally, they are used to realize the sealing between various parts of the cylinder and prevent gas leakage. The selection and installation of seals have an important impact on the performance and life of the cylinder.

In addition to the above main parts, the cylinder may also include auxiliary parts such as bushing, dust ring and sensor. These parts work together to enable the cylinder to work stably and reliably under various severe environments.

Characteristics of cylinders

◆ Simple structure: because there is no complex fuel system and ignition system, the maintenance cost of cylinder is relatively low. It is also easier to replace cylinder parts.

◆ Lightweight design: the cylinder uses gas as the power source, without complicated electrical or fuel system. This makes the cylinder ideal for applications where space is narrow and lightweight design is required.

◆ High output: the output force of the cylinder is proportional to the square of the cylinder diameter, so the cylinder can produce a large output force, which is very beneficial for applications requiring large thrust.

◆ Fast response speed: the power output response speed of the cylinder is fast, which can realize fast start/stop and fast control. This is very important for machines with high requirements such as forging machine tools and mold machine tools.

◆ Environmental protection and energy conservation: gas is used as the power source, without exhaust emission; The noise generated by the cylinder during operation is relatively low, which helps to improve the working environment; The cylinder can realize energy saving and improve energy utilization efficiency through proper throttling and control of gas flow.

◆ Strong environmental adaptability: the cylinder can work normally in high temperature and low temperature environment, and has dustproof and waterproof capabilities, which can adapt to various harsh environments.

Cylinders of different materials can be used to meet different working environment and use requirements,such as aluminum cylinder and stainless steel cylinder.

◆ Low user requirements: compared to devices such as electric motors that require electrical knowledge, the principle and structure of cylinders are simpler and easier for ordinary workers to master and use.

Categories

As an important component in mechanical transmission, the cylinder is classified in a variety of ways. The common cylinders are:

◆ Standard Cylinder: have uniform dimensions and interface standards, easy to install and maintain, and can install various accessories. Widely used in various industrial automation equipment and production lines.

◆ Rodless Cylinder: without conventional rigid piston rods, reciprocates directly or indirectly with the piston. It can be divided into mechanical coupling and magnetic coupling. Especially suitable for small cylinder diameter and long stroke.

◆ Rotary Cylinder: the output shaft swings, and the swing angle is less than 280 °. It is used for rotating, turning over and classifying objects and other occasions requiring swinging motion.

◆ Compact Air Cylinder: compact structure and small volume, suitable for occasions with limited installation space. Widely used in electronic, medical, packaging machinery and other high-precision, high-frequency use of the industry.

◆ Dual Rod Guided Air Cylinder: dual rod pneumatic cylinders have a certain anti-torsion and anti-side load capacity，which allows them to carry a certain amount of lateral force.

Guided pneumatic cylinder adds another high-precision guided rod, and equipped with high-performance sealing ring and dustproof design, which ensures stable piston motion and reduces leakage. It is used to achieve high-precision linear motion or load guiding.

◆ Mini Pneumatic Cylinder: also known as mini air cylinder pneumatic or mini air cylinder, it has small volume, light weight, sensitive action, and is easy to install and process. It is widely used in situations where installation space is small and small motion control is required.

◆ Stopper Cylinder: cylinder type, roller type, roller lever type and other types, mainly used on conveying line to stop moving articles.

◆ Rotary index table: the rotary index table is an actuator of worm gear and worm structure, which can realize circular rotation motion and index function. Commonly used in mechanical manufacturing, industrial automation, engineering measurement and other fields.

In addition, according to different air cylinder manufacturers, the common series are:

◆ ISO6431(ISO15552) Pneumatic Cylinder

◆ Airtac Standard Pneumatic Cylinder

◆ SMC Standard Air Cylinder   

Cylinders play a crucial role in modern industrial and mechanical fields. If you want to learn more about cylinders and their benefits in applications, please contact us. We are a professional pneumatic cylinder company that offers a wide range of articles, videos and other resources on cylinders to help you better understand their working principles, characteristics and application scenarios.You can click here to view more articles.

We believe that by gaining a deeper understanding of cylinders, you will be able to better understand the technology and applications in modern industrial and mechanical fields.