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Introduction of 3 Jaw Chuk

Views: 72     Author: Site Editor     Publish Time: 2021-01-27      Origin: Site

Introduction of 3 Jaw Chuk

Chucks are mechanical devices used on machine tools to clamp workpieces.The accessory of the machine tool is clamped and positioned by the radial movement of the movable jaws evenly distributed on the chuck body.The chuck generally consists of three parts: chuck body, movable jaw and driving mechanism of chuck jaw.The chuck body has a minimum diameter of 65 mm and a maximum diameter of 1500 mm. 

There are through holes in the center for passing through the workpiece or bar. The back has a cylindrical or short conical structure which is connected directly or through the flange to the end of the machine tool spindle.Chucks are usually installed on lathes, cylindrical grinders and internal grinders, and can also be used in conjunction with various indexing devices for milling and drilling machines.


It can be divided into: 2-jaw chuck, 3-jaw chuck, 4-jaw chuck, 6-jaw chuck and special chuck.It can be divided into: manual chuck, pneumatic chuck, hydraulic chuck, electric chuck and mechanical chuck from the point of use power.Structurally, it can be divided into: hollow chuck and solid chuck.


Introduction to 3-jaw chuck of lathe

The three-jaw chuck consists of a jaw disc body, a small bevel gear, a large bevel gear and a flat thread at the other end and three jaws.The three jaws have the same thread as the flat thread to match them, and the three jaws are uniformly distributed in the guide groove of the jaw disc body at 120 degrees.The taper hole of the claw disc body matches the outer taper surface of the front end of the lathe spindle and acts as a center. The key transmits the torque and finally locks the chuck body to the spindle with the nut.


When one of the small bevel gears is turned, the large bevel gear is driven to rotate, and the plane thread on the large bevel gear drives the three clamping jaws to move to the center or outward at the same time, thus realizing automatic centering.Centering accuracy is not high, about 0.05~0.15mm.There are three claws, one is front claw and the other is reverse claw. 

Some chucks can turn the claw back into reverse claw. When the reverse claw is replaced, larger diameter workpiece can be installed.Power chucks are automatic centring chucks, which can be made up of pneumatic, hydraulic or electric chucks with different power devices (cylinders, cylinders or motors).Cylinders or cylinders are installed at the back end of the spindle of the machine tool, and the wedge sleeve in the body of the chuck at the front of the spindle is pushed and pulled by a tie rod or pulling pipe pierced through the bore of the spindle. The axial advance and retreat of the wedge sleeve causes three clamping jaws to move radially at the same time. The chuck moves quickly and the clamping jaws move in a small amount, which is suitable for mass production.

Maintenance method of lathe chuck.

  • Lubrication is important in order to ensure that the lathe chucks still have a good accuracy after a long time of use.Incorrect or improper lubrication will lead to problems such as abnormal function at low pressure, weakened clamping force, poor clamping accuracy, abnormal wear and sticking, so the chuck must be lubricated correctly.

  • Put molybdenum disulfide grease (black colour) at least once a day into the nipple of the chuck until grease spills over the jaw surface or at the inner hole of the chuck (inner hole protective sleeve and connecting nut), but if the chuck rotates at high speed or if large quantities of water-based cutting oil are used in processing, more lubrication is required and must be determined according to different circumstances.

  • Always use an air gun or similar tools to clean the body of the chuck and the sliding surface at the end of the work.

  • Remove the chuck at least every 6 months, disassemble and clean it, keep the sliding surface of the clamping jaw clean and lubricate it, so as to prolong the life of the chuck.However, if cast iron is cut, thorough cleaning should be carried out at least once or more every 2 months to check parts for breakage and wear, or to replace new parts immediately.Full oil should be given after checking.

  • Different clamping modes or special fixtures must be used for different workpieces.Three-jaw chuck is only a general-purpose clamping device, which can damage the chuck if you use it to clamp irregular or strange work pieces. If the pressure of the chuck is not normal, the chuck will be under high pressure and the work piece will be clamped by the chuck after the machine is shut down, which will reduce the life of the chuck. Therefore, when you find that the gap between the chucks is too large, you must replace the new chuck immediately.

  • Cutting oil with anti-rust effect prevents rust in the chuck because rust on the chuck reduces the holding force and prevents the workpiece from being clamped.The lathe chuck maintenance is very important. If the correct maintenance method is not available, the lathe chuck will be used for a long time. With the wear of the chuck, the three claws will flare and deviate slowly from the center of the lathe spindle, which will increase the position tolerance of the machined parts.In this way, not only the accuracy will be greatly affected, but also the stability of the whole machine.Therefore, when using the lathe chuck, please be sure to do a good job of lathe chuck maintenance.


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