What are the precautions for the use of the positive jaw chuck?

The three-jaw chuck will reduce the coaxiality and flare phenomenon after a long period of use, which directly affects the machining accuracy and clamping reliability. The following method is simple and practical, and you can use it as a reference.

Taking the positive jaw chuck as an example, first clamp a round bar of appropriate diameter with an external clamp, start the machine tool, and turn the outer part of the jaw. Then a ring piece is clamped by means of internal support, the machine tool is started, and the inner part and end face of the jaw are turned.

Obviously, in this way, the coaxiality of the inner circle of the machined jaw and the spindle of the machine tool can be significantly improved, and the flare phenomenon can be eliminated, so as to obtain higher accuracy and achieve the purpose of correction. The following points need to be paid attention to in the specific application fashion:

1. Because there is inevitably a gap between the chute of the jaw and the chuck body, and the force direction of the jaw is just opposite to the force direction of the actual work when corrected, the modified chuck will appear flare when it is used. Therefore, the inner circle of the jaw should be pre-machined into a reverse flare with a certain taper (large inside and small outside), and the adjusted taper value can be determined by the test, which is the key to success or failure.

2. The outer circle of the round bar and the inner circle of the annular part need to be processed in advance and have a certain precision. And the inner diameter of the annular body should not be too small, otherwise it will make the concave arc of the jaw surface large and deep, and it is easy to damage the surface of the workpiece when clamping the large-diameter workpiece, which must be paid attention to.

3. Due to the high hardness of the jaw and the intermittent cutting, the cutting depth and the amount of pass should be small when correcting, and the cutting speed should not be too high. The tool material is preferably cemented carbide. If a small power head can be installed on the carriage, the effect is better if the grinding wheel is used for correction.

4. The purpose of this step is to establish a good benchmark to improve the correction accuracy, and it is best not to save this step.

5. This method can also be used to correct the error caused by improper installation or other reasons of the new three-jaw chuck, so as to improve the machining accuracy. The same principle can be used to correct the back-claw.

There are generally two common four-jaw chucks: one is a four-jaw self-centering chuck, and the other is a four-jaw single-action chuck. The former has the function of automatic centering, and the latter kind of each jaw can move independently, and there is no function of automatic centering, and there is no centering.

The full name of four-jaw self-centering chuck is manual four-jaw self-centering chuck for machine tools, which is composed of a disc body, four small umbrella teeth and a set of jaws. Four small bevel teeth and coil wire mesh, the back of the coil wire has a plane thread structure, and the jaws are installed on the plane thread in equal parts. Because the pitch of the plane rectangular thread on the coil wire is equal, the movement distance of the four jaws is equal, and it has the effect of automatic centering.

The full name of four-jaw single-action chuck is manual four-jaw single-action chuck for machine tools, which is composed of a disc body, four screw rods and one set of jaws. When working, four leading screws are used to drive the four jaws respectively, so the common four-jaw single-action chuck does not have the effect of automatic centering. However, various rectangular and irregular workpieces can be clamped by adjusting the position of the four jaws, and each jaw can be moved independently.

First of all, we need to find the right caliper, for example, if we correct the outer circle of 350 mm, we need a caliper of 0-500 mm.

Then we estimate the position of the four jaws first, so that the four jaws are evenly distributed around the chuck, and the prepared calipers are stuck on the required size, such as 350mm, and then the calipers are placed between the two pairs of jaws of the four jaws, so that the two pairs of jaws reach the position of the caliper, and the other two pairs of jaws find the correct position according to this method.

The workpiece is then clamped onto the chuck.

After the workpiece is clamped, the outer circle can be corrected with a magnetometer.

There are two types of jaws for four-jaw self-centering chucks, integral jaws and separate jaws. The integral claw is a card claw integrating the base claw and the top claw, and an integral claw is divided into four positive claws and four reverse claws. There are only four jaws for a set of separating claws, and each jaw is composed of a base claw and a top claw, and the function of the front claw and the reverse claw is achieved through the transformation of the top claw.

In addition, soft jaws can also be provided according to user requirements, and high centering accuracy can be obtained after random vehicle allocation (grinding) to meet the clamping requirements.

The jaws of the four-jaw single-action chuck have only one type of integral jaw. One jaw can be moved individually and is suitable for clamping eccentric and irregularly shaped parts.

Four-jaw self-centering chuck.

Function: The synchronous movement of the four jaws is suitable for clamping square and square parts, as well as shaft and disc parts.

Applicable machine tools and accessories: ordinary lathes, economical CNC lathes, grinding machines, milling machines, drilling machines and machine tool accessories - indexing head rotary table, etc.

Four-jaw single-action chuck.

Function: Each jaw can be moved individually, which is suitable for clamping eccentric parts and irregularly shaped parts.

Applicable machine tools and accessories: ordinary lathes, economical CNC lathes, grinding machines, milling machines, drilling machines and machine tool accessories - indexing head rotary table, etc.

Generally, the four-jaw chuck plane has grooves. First, use a tape measure to pull down the length of the workpiece. Then measure it out with a tape measure on the chuck (according to the engraved lines on the plane) to determine whether the two sides are symmetrical!

Then the workpiece is loaded and the accuracy is aligned. The long is corrected, and then the thin place is corrected, and the paw is corrected one by one, and the paw is made a mark when it is loose, and it is OK.