What Is an Air Chuck?
Actuators used in pneumatic systems are broadly classified into three types in terms of their method of operation: linear motion, rotational motion, and gripping motion.
For linear motion, air cylinders are commonly used. For rotary motion, there are air motors and rotary actuators for oscillating motion, both of which are used for circular motion. Clamping motion is used to clamp a workpiece by pneumatically opening and closing the fingers.
The linear motion of the cylinder is converted into an opening and closing motion of the fingers to enable the clamping motion of the workpiece. This is the air chuck.
Uses of Air Chucks
Air chucks are mainly attached to the end of industrial robots to grip workpieces by opening and closing the fingers to transfer and handle the workpieces. The size of the air chuck is generally expressed by the inner diameter of the cylinder tube, available in diameters ranging from 6 to 63 mm. Normally, the chuck is gripped by attaching a jaw suited to the shape of the workpiece to the finger section. The motion during chucking is accompanied by a conversion mechanism, such as a link. It is necessary to select the size and type of chuck by considering not only the gripping motion and gripping force but also the position of the gripping point and the moment during conveyance.
Principle of Air Chucks
There are three types of air chucks: parallel open/close chucks, fulcrum open/close chucks, and wide open/close chucks. Select the appropriate type according to the shape of the workpiece to be gripped. The parallel open/close chuck is a type in which the fingers move in parallel, with the number of fingers being 2 jaws, 3 jaws, or 4 jaws. The opening and closing motion is regulated by a guide mechanism, such as a linear guide or a sliding guide.
In the fulcrum open/close chuck, the linear motion of the cylinder drives the fingers directly by means of a link or cam motion. The guide mechanism is unnecessary, and the chuck is compact, but the design of the jaws attached to the end of the fingers is difficult because the gripping force varies greatly depending on the angle. Both types of parallel and fulcrum open/close chucks are available with either a double-acting cylinder or a single-acting cylinder for the opening/closing motion of the fingers. Those with a single-acting cylinder are available in two types: always open and always closed.
The wide open/close chuck is used when a large finger stroke is required. The cylinder motion directly drives the fingers, and the rack and pinion mechanism synchronizes the left and right fingers. The cylinder rod and guide rod are guided by a sliding bearing.