Advantages, Disadvantages And Classification Of Rodless Cylinders
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1. Working principle of Rodless Cylinder
The working principle of rodless cylinder is similar to that of ordinary cylinder, except that the external connection and sealing form are different. Both ends of the rodless cylinder are hollow, and the permanent magnet in the piston rod drives another magnet (moving part) outside the piston rod to move through magnetic force. This type of cylinder has high requirements for environmental cleanliness.
There is a piston inside the rodless cylinder, but no piston rod. The piston is installed in the guide rail, the external load is connected to the piston, and the piston is driven to move through air intake. The magnetic coupling movement is achieved by using the permanent magnet in the hollow piston rod to drive another magnet outside the piston rod. The advantages of this method are fast speed and high load, but the inner and outer magnetic rings are easy to disengage, so it is less used now. The mechanical contact rodless cylinder is directly connected to the external actuator through the piston, so that it follows the piston to achieve reciprocating motion.
2. Classification of rodless cylinders
Rodless cylinders are divided into magnetic coupling rodless cylinders and mechanical contact rodless cylinders.
Magnetic coupling rodless cylinder:
The piston drives the moving body outside the cylinder body to move synchronously through magnetic force. A set of high-strength permanent magnetic rings are installed on the piston. The magnetic lines of force act on another set of magnetic rings on the outside through the thin-walled cylinder. Since the two sets of magnetic rings have opposite magnetic properties, they have strong suction. When the piston is pushed by the air pressure in the cylinder, the magnetic ring sleeve outside the cylinder moves together under the action of the magnetic force. The thrust of the cylinder piston must be adapted to the suction of the magnetic ring.
Mechanical contact rodless cylinder:
A groove is opened in the axial direction of the cylinder tube, and the piston and the cylinder head move in the upper part of the groove. In order to prevent leakage and dust, stainless steel sealing tape and dustproof stainless steel tape are used to fix the opening on the cylinder heads at both ends. The piston frame passes through the groove to connect the piston and the cylinder head as a whole. The piston and the cylinder head are connected together to drive the actuator fixed on the cylinder head to achieve reciprocating motion.
3. Characteristics of rodless cylinders
Compared with ordinary cylinders, rodless cylinders can reduce the installation device by 1/2 under the same stroke;
No need to set up anti-rotation machinery;
Applicable to cylinder diameters of 10-80mm, with a maximum stroke of 41.5m;
Speed can reach 10m/s.
4. Disadvantages of rodless cylinders
Poor sealing performance, prone to external leakage. When using a three-position valve, a medium pressure type must be selected;
The load force is small, and in order to increase the load capacity, a guide mechanism must be added.
