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What is a Three-Jaw Chuck Machining Fixture? How does the Three-Jaw Chuck Work?

357 | Published by VMT at Sep 29 2021

The chuck is an important part of the turning process. As a clamping device, it has the function of fixing and safely clamping the workpiece. The chuck of the lathe has diversity to ensure that the material of the CNC turning parts can be kept stable and precise. This article will focus on the knowledge of the three-jaw chuck.

What is a three-jaw chuck?

The chuck is a fixture that clamps the material of CNC turning parts in a specific position. It is widely used in CNC machining factories. The three-jaw chuck uses the radial movement of three movable jaws evenly distributed on the chuck body to clamp the workpiece And positioning to the machine tool attachment. The three-jaw chuck also refers to the general-purpose chuck. When very fast, reasonable and accurate centering is required, this type is most suitable for clamping round and hexagonal CNC turning parts.

Three-Jaw Chuck Machining Fixture

Three-jaw chuck structure

1. Manual three-jaw chuck structure

The three-jaw chuck is composed of a claw body, a small bevel gear, a large bevel gear (the other end is a plane thread) and three jaws. The three jaws are matched with the same thread as the plane thread, and the three jaws are uniformly distributed at 120 in the guide groove in the jaw plate body. The taper hole of the claw body is matched with the outer taper surface of the front end of the lathe spindle, which plays a centering role, and transmits torque through the key. Finally, the chuck body is locked on the spindle with a nut.

2. Power three-jaw chuck structure

The power chuck is a self-centering chuck, which can be combined with different power devices (cylinder, oil cylinder or motor) to form a pneumatic chuck, a hydraulic chuck or an electric chuck. The air cylinder or oil cylinder is installed at the back end of the spindle of the machine tool, and the tie rod or tube passing through the spindle hole is used to push and pull the wedge sleeve in the chuck body at the front end of the spindle. This kind of chuck has rapid movement and small movement of the jaws, which is suitable for the production of large quantities of CNC turning parts.

How does the three-jaw chuck work?

Three-jaw chuck All the jaws of the three-jaw chuck are installed on a scroll, which uses the chuck wrench to rotate any of the three umbrella teeth on the circumference, thereby driving the plane thread to rotate and driving the three jaws Move together to play the role of self-centering and clamping parts. Three-jaw chucks are commonly used in lathes and indexing heads.

Chuck type

Chuck type	Features	Application
Zhongshi Power Chuck	1. The force of the wedge sleeve is directly transmitted to the claw guide area, so in the process of axial driving force transmission to the claw, 2. The friction loss is small 3. High radial and axial accuracy 4. High clamping force 5. High speed 6. Long jaw guide groove	High speed
Film chuck	1. The film clamping system has almost no abrasion after long-term use, and can always maintain stable accuracy. 2. The HSK installation method becomes the perfect interface for the "modular" replacement system. 3. After combining with HSK, the accuracy of reinstallation after the jaws are replaced is less than or equal to 0.005mm. 4. The medium transmission system can directly spray coolant or compressed air from the film chuck to the workpiece, or be used in the air tightness detection device of the workpiece.	High-precision grinding or hard turning
Rear pull type power chuck	1. High clamping accuracy. 2. Long guide wedge sleeve. 3. Super long guide support column. 4. Wedge transmission mechanism. 5. The support column with large contact surface has high stability.	High speed cutting
Floating chuck	1. The centering parts can be replaced, with elastic top and fixed top for self-centering clamping. 2. The connecting plate can be replaced and installed, with a centering flange, a short tapered surface, and a radial fine-tuning structure that is floating and flexible. 3. Lubrication by base jaws. 4. Self-centering mode is lubricated by wedge sleeve. 5. High clamping force.	Shaft workpiece machining
Power composite chuck	1. The 3 power telescopic jaws of the end drive that can transmit limited torque are supplemented, so that the clamping force of the end drive and the jaws are combined to transfer the high torque required for rough machining. 2. It has a wide range of use, and different workpiece diameters can be used by simply replacing the jaws and releasing the end face driver. 3. If you are using an end driver with a fixed center, the chuck needs to be driven by a hydraulic double-piston cylinder; if you are using an end driver with an elastic center, the chuck needs to be driven by a large- stroke Zhongshi hydraulic cylinder. This kind of chuck can use centralized lubrication.	Multi-axis CNC lathe machining