Single-acting actuator - what should you know about it?
Single-acting cylinder is one type of pneumatic cylinder. These types of elements are mainly used in heavy industry. They are great at generating power that is necessary for the operation of machines. What exactly is the structure of single-acting cylinders? How do they work? What is the price of such structural elements? How much does a single acting cylinder cost? You will find a description with answers to all important questions in this article.
Single-acting pneumatic cylinder
If you want to buy a reliable structural element of the machine, a single-acting cylinder will be an excellent choice. The scheme of the structure of the pneumatic actuator is very simple. The most important element of its design is the piston, which is equipped with an additional magnet. Another important part is the piston rod, i.e. a simple structural element of the actuator, which allows the energy generated during operation to be transferred from the piston to the machine it drives. The piston rods are reciprocating. All elements for generating and transmitting energy are located in the covers. The last important element of the actuator structure are seals. Thanks to the use of high-quality seals, we can be sure that the actuator will serve us for a long time. Before buying this part, it is worth paying attention to the material from which the seals are made. If the actuator is to operate in difficult conditions, in contact with corrosive substances, oils or high temperature, seals of a stronger material should be selected. As a result, the service life of this structural element will be extended.
Simple design ensures reliability. Before making a purchase decision, it is also worth understanding how a single-acting pneumatic cylinder works. The principle of operation of this type of element is very simple. In the simplest terms, a pneumatic actuator generates mechanical energy from compressed air energy. How does this happen? The cylinder is inflated with air. When the mechanism is actuated, the air is forced against one end of the actuator by the working element. This causes the air to be compressed. Thus, energy is produced. With it, an external device can be driven.
Due to the applied structural elements of the mechanism and solutions that allow for the production of energy, there is also another name for this type of actuator - a single-acting piston actuator.
It is thanks to the pneumatic actuators that we are able to easily set in motion very heavy machines or lift objects weighing several tons. The movement of the piston rod allows for the generation of large amounts of energy that enable us to do this. We would never be able to do this with the strength of human muscles. In addition, the actuators allow you to achieve uniform and regular movement, which is another great advantage.
If we intend to use pneumatic actuators, it is worth remembering about ensuring high air quality. Contaminants that can be found in the compressed air have a negative effect on the components of the pneumatic cylinder. They can lead to damage and shorten the life of the mechanism. For this reason, the actuators should be supplied with compressed air class 5, in accordance with ISO 8573-1-2010. It is also worth having units for air preparation, such as AGD-SAU stations. These types of stations are responsible for pressure regulation and air filtration.
Single-acting, spring-loaded actuator
Single-acting pneumatic cylinder with spring performs the working movement thanks to the energy from the compressed air, while the return movement is performed thanks to the spring. During movement, the piston squeezes it, and the generated energy allows the piston to be withdrawn due to the stretching of the spring. The single acting spring actuator can be pull or push. They are distinguished by the position of the piston rod in the starting position:
- The single-acting, pushing cylinder has a retracted piston rod in the starting position. This compressed air extends the piston rod through the use of mechanical energy. The spring then causes this structural element of the actuator to return to its place.
- The single-acting, pulling cylinder has the extended piston rod in the starting position. In this case, compressed air is introduced from the side of the front cover. This pulls the piston rod into the cylinder.
Both the single-acting pneumatic actuator, pushing and the actuator with the spring-pulling, perform perfectly well in their role. It is worth knowing that the stroke of single-acting push cylinders does not exceed 100 mm. For this reason, it is good to bear in mind that this type of cylinder has a very limited stroke. This, in turn, may translate into low work dynamics. Due to the low stroke, speed and dynamization of the work of such an actuator, it can be a disappointment for people expecting a very fast pace of the mechanism's work. Importantly, the low stroke is also related to the appropriate cushioning of the cylinder. Due to the use of a shock absorber seal, air out of the cylinder is prevented when the shock absorber sleeve enters. The air is directed outside through a small opening in the cylinder cover. Thanks to this, the actuator amortization is appropriate, which has a direct positive effect on the durability of this mechanism. The cushioning mechanism does not reduce the dynamics in the case of cylinders with a long stroke, while in the case of cylinders with a stroke of up to 100 mm, the dynamics is limited, because the movement is stopped shortly after it starts.
The single-acting spring-loaded actuator offers numerous advantages, including, in particular, the low operating costs of the actuator. Due to the use of a spring, these types of mechanisms consume less air. In addition, it is worth knowing that in the event of failure of this element, repair is very simple and cheap. The maintenance costs of such mechanisms are also not high. Single-acting actuators with a spring do not require extensive infrastructure from us - they do not generate the need for a large resource of additional equipment.
In conclusion, operating a single acting spring actuator is not associated with high costs. What's more, the purchase of these elements also does not generate high costs. You don't have to spend a lot of money on a single-acting pneumatic cylinder! The price of the mechanism depends on the specification of a specific actuator, but it will certainly not exceed several hundred zlotys.
When considering single-acting actuators, it is possible to consider the difference between a single-acting and double-acting actuator. There are differences both in the construction and the purpose of this type of mechanisms. First, a single-acting cylinder is equipped with one working chamber. This is the basic element that distinguishes these types of mechanisms, because the double-acting cylinder works simultaneously in two working chambers. As a result, it can perform a working movement in both sides, and not - as in the case of single-acting cylinders - only in one. This is possible because the two chambers are alternately supplied with compressed air.
The advantages of double-acting cylinders are certainly the lower stroke length limitations of single-acting cylinders. Most single-chamber cylinders are limited to a stroke length of 100 mm, while in the case of dual-chamber cylinders, the stroke length limitations are only related to the design solutions used in a specific mechanism. However, it is worth noting that the long stroke increases the mechanical load on the actuator. This in turn translates into the need for larger bearing diameters and longer wear rings, resulting in an increase in the size of the entire mechanism.
It is worth noting, however, that single-acting actuators are less emergency due to their simpler structure, and thus - cheaper to operate. Their repair and maintenance is much more profitable. In many cases, the advantage of single-acting cylinders is also their compactness - they are usually smaller than double-acting cylinders.
Single-acting pneumatic cylinders - application
It is worth knowing that the very simple design and effective operation make the single-acting pneumatic actuator perfect for operation in extreme conditions. In such circumstances, it is often not possible to use more advanced electric actuators - e.g. due to the inability to supply electricity to a given place. The single-acting pneumatic cylinder works with compressed air, so it can fulfill its tasks in virtually every possible place. It should be remembered that due to their reliability, actuators of this type are also used where they come into contact with very high or very low temperatures. In this case, seals made of materials such as Teflon or Viton, i.e. individual types of synthetic rubber, are used. As a result, the extreme temperatures do not endanger the mechanism.
Pneumatic actuators are used in various industries. They are used in the metallurgical and metallurgical industries as well as in the food industry. Pneumatic cylinders are most likely used in every factory, for example in production lines and in presses. Single-acting pneumatic cylinders are also used in the wood industry, and more precisely in wood processing. It is worth knowing that the single-acting pneumatic cylinder is very simple and safe to use. The level of security of people working with this type of mechanisms is really high.
In the face of increasing awareness of topics related to ecology and wasting non-renewable resources, it is worth emphasizing that pneumatic actuators are neutral to the environment and do not generate pollution.
On a daily basis, we do not realize how useful a single-acting actuator is. It is used in the construction of many objects that surround us. Without this type of mechanism, it would be impossible, for example, to open the door in a car. Besides, surely every DIY enthusiast knows how many simple tools use pneumatic actuators. The actuators are also used when the unloading platforms are used by trucks. Thanks to the actuators, the work of emergency services is also easier - these elements can be found, among others, in cutters and spreaders necessary for rescuers.
Single-acting cylinder: frequently asked questions
How much air does a single-acting pneumatic cylinder consume?The amount of air consumed by the actuator is an important factor for technical and economic reasons. The mechanism's air requirement can be calculated using the formula V = l × n × S × e, where:
- V - air consumption,
- l - actuator stroke length,
- n - number of actuator operation cycles per minute,
- S - actuator active surface,
- e - compression ratio.
What is the difference between a push and a pull single acting cylinder?In the case of a single-acting push cylinder, compressed air causes the piston rod to extend, while a spring causes this element to return to its place. On the other hand, the single-acting, pulling cylinder has an extended piston rod, which is drawn into the cylinder by compressed air.
Why choose a single-acting cylinder?A single-acting cylinder is an excellent choice due to its wide range of applications, including in the mining, automotive and agricultural industries, and in production machinery. A single-acting actuator will prove itself wherever one-sided mechanical force is to be used. In addition, single-acting cylinders are cheap to operate and maintain.