One of the screws is a screw cut using a lathe. In the screw cutting process, it is possible to process male screws and female screws with cylindrical work, such as large outer diameter screws and special screws that cannot be done by tap processing. In this article, I will explain the task of screw cutting by the lathe and how to select a turning chip.
The following issues generated by the lathe are as follows.
A dedicated twist cut tip is used for screw cutting by lathe. Since the selection of a turning chip affects not only processing efficiency and tool life, but also screw accuracy, appropriate chip selection is required according to the screw standard and work material.
.In the screw cut, burrs may be more likely to appear depending on the type of turning chip and work material. Burrneeds to be processed reliably because it causes poor screws or contamination inside the machine.
When a chipping (missing of the blade) occurs, it leads to poor screw accuracy. It is likely to occur when cut deeply, and it is due to a large amount of cut amount and a burden on the chips. As the twist is cut deeply, the area where the work and the tip combine are large, so the burden on the chip increases even if the cut is small. The screw accuracy is tested using a measuring tool such as a screw gauge, but it is necessary to pay attention to mass production processing that only performs extraction inspection.
There are the following measures to improve the accuracy of screw cutting by lathe and prevent burries.
There are three types of typical turning chips used in screws: full profile, no finish blade, and multi -point chip. It is important to select an appropriate chip that suppresses each characteristic.
Full profile (with finish blade) is the most common turning chip. Highly accurate screw cutting is possible to process the entire contour including the top of the screws and the valley bottom. Since the nose R is larger than the finished blade (V-shape) chip, it can be processed with a small number of passes. In addition, it is not necessary to remove the burrs because of the finished blade, but the number of tools used increases because it is necessary to prepare a different turning chip according to the screw pitch.
Finished blade (V -shaped) is a turning chip used in multiple twisting processing. If the angle of the screws and the corner R are the same, one turning chip can handle different screw pitches, so you can reduce the number of tools used. Since the vertex of the screws is not processed, be careful about the occurrence of burrs. In addition, the chip nose R is too small to cover the pitch range, so the tool life is shortened.
The multi -point chip is a mountain -shaped turning chip with multiple processing points on the full profile. Since the number of passes is small, the tool life is extended and productivity is improved, so the processing cost is reduced. In 3 points of turning chips, productivity increases tripled, but it is important to pay attention to the finish accuracy because the contact surface of the edge of the blade is increased and the cutting resistance increases. It is necessary to secure a space to escape the edge of the blade at the end of the processing.
In the screw cutting process, it is necessary to be careful because burrs are likely to occur at the entrance and exit of the screw mountain. In order to remove burrs, it is effective to perform the following 1-3 processes. Squeeze the screw entrance / exit according to the screw angle Zero -cut the outer diameter with a normal turning chip Zero -cut the screws with a screwed cut tip
*Zero cut is a processing method that traces the process once processed.As a measure to improve chipping If the screw -cut fee is large, the load applied during the screw entrance or processing may cause large chipping. In that case, the lower processing is performed with a 55 ° or 60 ° chip installed before finishing, and the chipping can be prevented by leaving the aging properly.
When processing the vertex and valley bottom of small nose R (rounded corner), it is also effective to use the same angle to use a large stream R tip to perform the lower processing.
In this article, we explained the task of screw cutting by the lathe and how to select a turning chip. NC lathes can be performed relatively easily by using a screwed cycle, but in order to prevent burrs and improve the screw accuracy, selection of turning chips and appropriate subordinate processing are key.
