Rodless cylinders are pneumatic drives and – as the name suggests – do not have a piston rod. Although they don't have a piston rod, they execute linear movements, which is why they are also known as linear drives. Rodless cylinders are used wherever a short installation length is advantageous and where the force has to be absorbed as consistently as possible. They also allow much longer travel distances with strokes of up to 8.5 m, which is not feasible for a standard cylinder with piston rod.
Rodless cylinders belong to the group of pneumatic cylinders that are operated using compressed air. They are used in a wide variety of pneumatic applications, such as in conveying, drive or handling technology. A characteristic feature of mechanically coupled cylinders is that power is transmitted via a lateral connection on the piston. This requires them to have a slot in the profile barrel. In the case of magnetically coupled cylinders, the force is transmitted through a closed profile barrel and a magnetic field. The installation length required in both variants is significantly less than with comparable piston rod cylinders.
The major advantages of cylinders without piston rods are longer travel strokes and a shorter design, which is why they can be used very flexibly. Rodless cylinders are therefore the first choice when space is limited. Thanks to available mounting slots on various sides of the mechanically coupled rodless cylinders, modular components, such as brakes or sensors, can be installed directly on the cylinders themselves. In addition to being very flexible to install, an inner and an outer sealing strip guarantee good sealing properties. This allows for long strokes, without restrictions.
• For any stroke length, piston rodless cylinder is only half as long as conventional cylinders.
• For long strokes, there is no risk of piston rod deflection.
• In the case of a piston rodless cylinder with guide, either slide guide or ball bearing guide can be chosen, which can be used for applications that require torsion and force, for example, a multi-axis system.
• The piston is driven by compressed air and has a risk of compressed air leakage due to its connection through the profile tube. This is not the case with the magnet.
• Due to the same groove, the rodless cylinder is more sensitive to dirt particles which limits its application somewhat despite being covered with magnetic bands.
• The above disadvantages are overcome by magnetically coupled cylinders, but these possess less force. If the (counter) force the product to be moved exceeds the force of the magnetic coupling, the piston will no longer guide the slide. The cylinder then only moves with its inner parts until one can again guide the piston past the magnet.
A rodless cylinder works by using a piston that is connected to an internal carriage inside the cylinder body. The carriage is guided by linear bearings or slides and moves back and forth along the inside of the cylinder body.
When compressed air pressure is supplied to the rodless pneumatic cylinder, it enters the cylinder through inlet ports and pushes the piston inside the carriage, causing it to move in linear direction. The air pressure behind the piston is released through exhaust ports on the opposite side of the rodless cylinder.
To reverse the motion of the carriage, compressed air is supplied to the opposite end of the cylinder, pushing the piston and carriage in the opposite direction. The exhaust ports on the original side of the rodless cylinder then release the air pressure.
The carriage typically includes a cylinder slot or bore for mounting and moving payloads, such as sensors, grippers, or other components. The carriage is also designed to seal against the inside of the cylinder body to prevent air leaks and maximize efficiency as well as save energy.
This traditional pneumatic cylinder is commonly used in applications that require long strokes or the ones that have limited space. They are also useful in applications that require precise positioning and smooth, consistent motion.
There are several types of pneumatic rodless cylinders available, each with their own unique design and capabilities. Please see below some common rodless cylinder types:
1. Cable cylinders: This pneumatic rodless cylinder uses cables to transmit the force from the internal carriage to the external load. They are often used in applications that require high speeds and high loads.
2. Magnetic cylinders: These pneumatic cylinders use magnets to move the internal carriage along the cylinder body. They are often used in applications where a clean, hygienic environment is required, as they do not require any external lubrication.
3. Belt-driven cylinders: This rodless cylinder uses a belt to transmit the force from the internal carriage to the external load. They are often used in applications that require high accuracy and repeatability.
4. Toothed belt cylinders: This pneumatic rodless cylinders use a toothed belt to transmit the force from the internal carriage to the external load. They are often used in applications that require high accuracy and precise positioning.
5. Screw-driven cylinders: This rodless cylinder uses a screw to transmit the force from the internal carriage to the external load. They are often used in applications that require the same force in both directions and precision, such as in the machining industry.
6. Guided cylinders: This cylinder slides uses external guides to support and guide the carriage along the cylinder body. They are often used in applications that require high precision and repeatability.
1. Cylinder Body: The cylinder body is the main housing for the piston and carriage assembly. It is typically made of aluminum, stainless steel, or other materials that can withstand the operating conditions of the application.
2. Piston: The piston moves the component of the cylinder that generates the force required to move the carriage. It is typically made of aluminum or other lightweight materials to minimize the weight of the moving mass.
3. Carriage: The external carriages are the internal components of the cylinder that moves along the cylinder body. It is typically guided by linear bearings or slides to ensure smooth and similar stroke length.
4. Seals: Seals are used to prevent air leaks and maintain the efficiency of the cylinder. They are typically made of rubber or other materials that can withstand the operating conditions of the application.
5. Inlet and Exhaust Ports: Inlet and exhaust ports are used to supply and release compressed air to and from the cylinder. They are typically located on opposite ends of the cylinder body.
6. Mounting and Payload Attachment Features: The carriage of the rodless cylinder often includes features for mounting and attaching payloads, such as sensor, gripper, or other tools.
7. Optional Components: Depending on the specific application requirements, a rodless cylinder may also include optional components, such as position sensor, shock absorbers, or flow control valves, to improve the performance and safety of the cylinder.
A cylinder barrel is a component of a pneumatic or hydraulic cylinder that provides a housing for the piston and other internal components. It is essentially the outer cylindrical portion of the cylinder that encloses the working fluid and provides a sealed environment for the piston to move back and forth.
The cylinder barrel is typically made of materials that can withstand the operating conditions of the application, such as aluminum, stainless steel, or other metals. It may be smooth or have grooves or ridges to provide a surface for seals to ride against and prevent fluid leaks.
In addition to providing a housing for the piston and other internal components, the cylinder barrel may also include mounting and attachment features for connecting the cylinder to other components or structures in the system. It may also have ports for inlet and outlet of fluid, as well as other optional features such as position sensors or cushions for absorbing impact at the end of the stroke.
Overall, the cylinder barrel plays a critical role in the function of the cylinder, providing a sturdy and reliable structure for the internal components to operate within, while also ensuring that the working fluid is contained and properly directed to achieve the desired motion.