pneumatic circuit for tool handling in cnc machine tools

PNEUMATIC CIRCUIT FOR TOOL HANDLING IN CNC MACHINE TOOLS

1. Functional and Operational Requirements

The name CNC stands for computer numerical control. The CNC machines are electro- powered machine tools that copy computer programming inputs. These CNC machines control tools such lathes, mills and grinders. The pneumatic circuits are required in CNC machines to hold and machine the workpiece.

2. Circuit

Fig.16.9 illustrates a typical pneumatic circuit used in a CNC lathe machine for holding the workpiece/tool and machining the workpiece. This circuit uses solenoid-operated 4/2 DC valve, a solenoid-operated spring offset 4/3 DC valve, an air motor and a double-acting cylinder.

3. Operation

Extension and retraction of cylinder (i.e., clamping and unclamping of workpiece/tool): 

When the solenoid of the 4/2 DC valve is energized, the air flows into the blind end of the cylinder and the cylinder extends. This cylinder extension is used to clamp the workpiece (or the tool). When the solenoid of the 4/2 valve is de-energized, the air flows to the rod end of, the cylinder and the cylinder retracts so that to unclamp the workpiece (or the tool).

Actuation of air motor (i.e., rotation of tool/worktable): When the solenoid of 4/3 DC valve is energized, the air flows into inlet port of the air motor and hence the motor rotates. This motor rotation is used to rotate the tool (or the worktable). When the solenoid of the 4/3 DC valve is de-energized, the air motor rotates in the opposite direction.

The actuation of pneumatic cylinder and air motor are synchronized based on the application requirement through part programming.