What Is a Cam Positioner?
A cam positioner is a device used in the fields of mechanical engineering and automatic control.
They are intended to replace mechanical cams and simplify their structure. A mechanical cam is a mechanism that rotates a circular or elliptical cam shaft to operate a part that performs a specific action based on its shape.
Cam positioners typically use a sensor or encoder to detect the angle of rotation or position of the shaft and feed it back to a control system. The control system controls the shaft based on a pre-set cam profile.
In other words, the cam profile can be set as a profile in the cam positioner to replace a conventional mechanical cam. This avoids the complex mechanisms of mechanical cams and simplifies the structure.
Uses of Cam Positioners
1. Automotive Industry
The are used in engine valve control, offering precise timing and valve opening/closing control for engines, thereby improving fuel efficiency and reducing emissions.
2. Machining
They are used in machining equipment, such as machine tools like lathes and milling machines to control accurate positioning and cutting movements of tools.
3. Assembly Line
Used in product packaging and assembly lines. Accurate position control allows product packaging and assembly operations to be performed quickly and accurately.
4. Robotics
Used in robotics and automation systems. Cam positioners may be used in motion control and positioning of robotic arms.
5. Printing
Cam positioners are also used in the printing process. They are used to control the position of the print head and ink supply.
Principle of Cam Positioners
A cam positioner consists of elements such as measurement by a sensor, information processing by a control system, and position control by an actuator. This enables precise control of the position and speed of the axis to achieve the desired motion.
1. Sensor or Encoder
Cam positioners use sensors or encoders to measure the angle of rotation and position of the axis. This detects the current state of the axis and provides feedback to the control system.
2. Control System
Cam positioners work in conjunction with a control system. The control system receives feedback information from the sensors and encoders and calculates the difference from the target axis rotational position and speed.
3. Actuator
The control system sends commands to actuators to control the position of the axis. The actuator may take the form of an electric motor, hydraulic cylinder, or pneumatic cylinder. The actuator moves the axis to a precise position based on commands from the control system.
4. Feed-Forward Control
Feed-forward control may also be used with cam positioners. Feed-forward control uses position and velocity information predicted in advance based on a profile to control the actuator. This minimizes the effects of delay and response time and allows for more accurate control.
Types of Cam Positioners
The main types of cam positioners are as follows:
1. Optical Cam Positioner
An optical sensor is used to detect the convex position of the cam. The optical sensor detects the reflection or transmission of light between the cam and the convexity of the cam to obtain position information.
2. Laser Cam Positioner
Uses a laser sensor to detect the position of the cam’s convexity in a non-contact manner. The position information is obtained by analyzing the reflection or scattering pattern of laser light.
3. Encoder Positioner
Uses a device called an encoder to detect the angle of cam rotation. The encoder generates a pulse signal in response to cam rotation to acquire position information.
4. Potentiometer Positioner
A variable resistor called a potentiometer is used to detect the position of the cam. The resistance value of the variable resistor changes with cam rotation to acquire position information.