Sep.20.2024
The electric actuator is divided into two motion types: linear stroke and rotary stroke (where rotary stroke is further divided into multi-turn and part-turn, and linear stroke is usually push-pull structure). It is commonly used to control various valves to form electric valves or electric control valves (e.g., ball valves, butterfly valves, gate valves, control valves, single-seat valves, etc.) using AC alternating current or DC direct current as the driving power source. According to the operating mode, it is classified into two categories (electric switch type and electric control type).
Here, Fleyenda Flow will briefly explain the difference between linear stroke and rotary stroke.
Linear stroke refers to the distance the actuator moves in a straight line during operation, while rotary stroke refers to the angle the actuator rotates around its axis during operation.
Differences and applications of them:
Different motion types: The most obvious difference between linear stroke and rotary stroke is their motion types. Linear stroke involves the actuator moving along a straight line, while rotary stroke involves rotational movement around the axis. Generally, linear stroke actuators have faster movement speeds, suitable for situations requiring rapid control, while rotary stroke actuators have slower rotational speeds, suitable for situations requiring slow position adjustments.
Different application scenarios: Linear stroke and rotary stroke actuators also differ in their application scenarios. Linear stroke is mainly suitable for situations where linear position control is needed, such as welding lines and assembly lines in the automotive industry. On the other hand, rotary stroke is mainly suitable for situations where rotational angles are required, such as in robotic arms.
Applications of linear stroke: In automated production lines, linear stroke is commonly used. For example, machine arms on assembly lines often need to perform linear movements, such as grabbing, assembling, and transporting various items. Additionally, in the automotive industry, operations like welding, painting, and spot welding require the use of linear stroke actuators.
Applications of rotary stroke: Rotary stroke actuators are mainly used in situations requiring rotational angles. For instance, if a robotic arm is handling an item that needs to be rotated for processing or operation, or if there is a need to control the rotation of certain equipment, such as cutting, printing, or stamping.
In summary, linear stroke and rotary stroke actuators play indispensable roles in motion control systems, each suited for specific automation applications.
The electric actuator has a simple structure, small product volume, light weight, and is mainly composed of an execution mechanism and a control mechanism. These two parts respectively perform the functions of adjustment and propulsion. The control mechanism, driven by external force or the action of the execution mechanism, produces corresponding displacement to regulate the flow of the conveying medium. The execution mechanism is responsible for driving the action of the control mechanism based on the size of the control signal from the controller. Additionally, auxiliary devices such as valve positioners and handwheel mechanisms are often included to ensure the reliability and adjustment quality of the actuator, providing stability in structure and operation.
The working principle involves a pair of gears in the gearbox driving the active small gear (Z=8), which in turn drives the counter to work. If the counter is set to the correct position for valve opening or closing and reaches the pre-adjusted position (number of rotations), the cam will rotate 90°, causing the microswitch to actuate and cut off the power to the motor, stopping its rotation. This controls the stroke (number of rotations) of the electric device. This mechanism is widely used, especially in places where flammable and explosive conditions are a concern due to its high safety factor, strong operational functionality, and stable performance.
Advantages of electric actuators: Electric actuators have the advantages of easy power supply, fast signal transmission, long transmission distance, convenient centralized control, high sensitivity, high electrical control accuracy, ease of operation, and simple installation and wiring. However, they have a more complex structure, lower thrust, and a higher average failure rate compared to pneumatic actuators. They are suitable for places where explosion-proof requirements are not high and where there is a lack of air supply.
Disadvantages of electric actuators: The complex structure of electric actuators leads to a higher probability of failures. Due to their complexity, technical requirements for on-site maintenance personnel are relatively high. The motor generates heat during operation, and frequent adjustments can lead to overheating. Although there is thermal protection, it can increase wear on the gearbox. Additionally, electric actuators operate more slowly, taking a longer time to respond to signals from the controller and move to the appropriate position compared to pneumatic or hydraulic actuators.
Electric actuators are mainly applied in the following three major fields:
Selection considerations:
