1. Centerline and tool holder of slender shaft parts

Applied in processing

When turning long shaft blanks with diameters greater than 10 to 12 times (such as lathe bar, screw, etc.), due to the difference in the rigidity of machining shafts, the effects of cutting force, cutting heat and vibration are increased, so bending and taper are prone to occur in turning , Waist drum, bamboo and other defects. In addition, vibration occurs during turning, which affects the roughness of the workpiece surface. In order to prevent this phenomenon, we can use the special support fixture such as the center frame. Lathe and positioning step tool holder is one of the lathe accessories, using the clamping jack and the center lathe or the front and rear jack and tool holder clamp to improve the rigidity of the cutting system.

Using these additional mounting card tools can improve the mounting card rigidity of the workpiece, reduce vibration, ensure processing quality, prevent parts from generating drums, improve the geometric accuracy and surface roughness of the workpiece surface, allow batch processing, and improve labor productivity. The following describes the application of the centerline of the slender shaft part and the tool holder.

First, the application of the center frame in the processing of slender shaft parts

1. Structure of the center frame

The centripetal or centrifugal force position of the three claws can be adjusted to match the workpieces with different diameters, and the claw fixing screws are locked to fix the claws in the desired position.

2. Use the center frame

(1) How to adjust the center frame

Before the workpiece is installed on the center lathe, the groove of the center frame claw can be installed in the middle of the blank. The diameter of the groove is the same as the diameter of the workpiece, and the width is slightly wider than the claw. Next, install the central shelf at an appropriate position on the bed surface, open the cover, install the workpiece between the two thimble (the end of the bed should be adjusted first), use a syringe or dial indicator to check whether the groove is jumping, and then close the cover , Adjust the 3 feet of the center frame to make it lightly contact with the workpiece groove. At this time, please turn the workpiece slowly to see if it can move. It is best to tie a copper belt or a flat belt between the claw and the workpiece. Add a little lubricating oil or use the three claws made of rubber to prevent the surface of the workpiece from being scratched. When turning large workpieces or workpieces, a central lathe with rolling bearings must be used.

(2) Turning steps

When turning, first turn the left end, then adjust the direction of the workpiece, use the same method to install and adjust the workpiece, and turn the other end.

For workpieces that already have an outer diameter. Moreover, when there should be no scratches on the surface, it is best to use a center frame with rolling bearings. If there is no center frame with rolling bearings, replace it with an auxiliary sleeve. When using, put the sleeve on the outer circle of the work piece, tighten the screw (there is a copper retaining ring between the screw and the work piece), and correct the outer circle of the sleeve with a dial indicator. If the outer ring of the sleeve is not concentric with the workpiece, the screw must be adjusted until it is concentric.

If you use a lathe to machine the end surface or inside of the long shaft, and trim or thread at one end of the shaft, you can move the center frame to the end of the near shaft. But before adjusting the three claws, pay attention to making the workpiece concentric and concentric, and then adjust the claws. Otherwise, the workpiece will quickly fall off the claw wheel because the center of rotation does not match the center of rotation of the spindle

Then clamp the end surface of the workpiece.

When turning a slender shaft using a cnc machining center, according to the overall machining needs of the shaft length, it can be divided into the following two categories:

1) The parts can be turned directly by the center turning lathe or by turning. The supporting claws of the center frame are made of cast iron or bronze and are used in the middle of the parts. The supporting surface of the parts must have fixed roughness and roundness requirements. Otherwise, the accuracy of the parts may be affected. The operation steps are as follows:

In the middle of the workpiece, in the frontal direction, the diameter of the cylindrical groove of about 100mm must be larger than the required size of the workpiece. When there is a groove, in order to reduce vibration, you can slow down and cut with a small knife.

Install the central station. When turning the lathe, adjust the three claws so that it gently touches the workpiece.

Rough turning. Cut from the end of the bed to the head of the bed until it stops at the grooved part.

Workpiece U-turn clamping.

Adjust the center frame support claw. A fine-grained emery cloth is placed between the processed surface and the three claws. The back of the emery cloth is attached to the rough. The sand grains face the three claws. Adjust the three claws to gently support the processed surface.

2) Long-axis workpieces that do not need to be processed in the middle can be supported by both the sleeve and the center lathe. Due to the irregular surface of some blanks, the middle section is not suitable for flat grooves, so the adjusting sleeve and the center frame can be used in combination. Adjust the sleeve, the use steps are as follows:

Adjust the screws at both ends of the sleeve so that the axis of the sleeve is consistent with the axis of rotation of the lathe spindle.

Install the center frame so that the support claws of the center frame contact the sleeve outer ring and rotate evenly.

Turning. Until the end is turned.

Turn the parts around
The center frame supports the adjustment of the position of the claw to contact the swiss turning surface of the part, adjust the supporting claw, so that the lathe surface rotation axis of the part is located at the center of the lathe main shaft rotating uranium can be combined and turned.

(3) Precautions

1) When using a center lathe to segment or turn a workpiece that can be turned, please pay attention to the following points:

During the entire process, pay attention to lubricate and maintain lubrication to prevent wear or “bite marks”. Like the case of fever, it is necessary to use touch to grasp the friction and heat of the workpiece and the central three claws at any time, and to adjust the central three claws in a timely manner, not to wait for “squeak” or smoke.

If the machined shaft is long, you can use more than two center lathes at the same time.
(2) When using a long-axis workpiece that does not need to be processed in the middle part of the center car:

Smoothly adjust the outer surface of the inner sleeve.

The inner l of the sleeve is 20 to 30 mm larger than the outer circle of the machined part.

When turning at low speed, lubricate the contact surface of the sleeve and the support sleeve of the center frame with oil. When turning at high speed, use the adjusting sleeve cooling lubricant to pour into the outer surface of the sleeve to cool.

Second, the application program of the slender shaft part of the tool holder

1. Use with knife holder

The tool holder is mainly used for turning long shafts that are not allowed to be connected, such as high-precision smooth shafts and long screws. Unlike the tool holder, the central lathe has only two claws, and the other claws are replaced by knives.

The knife holder is fixed on the big carriage that moves with the knife holder.

In order to improve the machining quality of the workpiece and make the turning smoothly, the tool holder that can turn the small diameter and slender shaft on the ordinary lathe has been improved and reformed. Together with the claws of the tool holder, a circle is formed, and the aperture of the ring is 0.02 to 0.03 ram larger than the outer circle of the workpiece, and is fixed on the large drag plate. During use, the inside of the sleeve is guided by the diameter of the hair, and through cold drawing, other diameters are selected as required. This simplicity and tool holder are easy to manufacture and convenient to use. Suitable for mass production of slender shaft parts.