There are a variety of cutting tools, common thread turning tools, tap, squeeze tap, thread cutter and so on. How to choose the right machining tool? The choice of tool is actually the choice of processing methods, each processing method used by the different tools. For the processing of threaded holes, there are several common ways: tapping, turning, extrusion, thread milling. Here we first understand the advantages and disadvantages of various process methods and the use of restrictions, in the actual production, we can according to the characteristics of these processing methods, from a technical and economic point of view to analyze the use of which tool for processing.
1, tapping
Tapping is a widely used method of thread hole processing. It can use the shape of the CNC tool to determine the shape of the thread, so no special machine tool processing, in the ordinary machine tools, production lines and processing centers can be used. The tapping process is the first turn of the taps to be cut, turned to the bottom of the thread, leaves the workpiece, cuts it in a very narrow space and discharges the chips. For different processing conditions, different processing materials, the selected tap type is also different. In the small diameter and mass production using tap tapping.
2, turning processing
Turning thread is the use of indexing blade for turning, the production of commonly used triangular thread, the thread turning part of the shape of the thread should be consistent with the axial cross section. When turning, the workpiece must be moved longitudinally by one lead (single thread, lead = pitch) to produce the correct thread. Car triangular thread commonly used methods are the following three:
A, straight into the law car thread. When the thread is threaded, the workpiece is checked by the test, and the pitch is in accordance with the requirements. The radial direction is perpendicular to the workpiece axis and is repeated several times until the thread is good. This type of turning method is more accurate. As the two knives at the same time cutting and chip removal is not smooth, force, easy to wear the knife, the chip will scratch the thread surface.
B, oblique into the law car thread. When the workpiece pitch is greater than 3MM, the general use of oblique method of machining the thread, the incision method is the turning edge along the side of the thread in the radial feed at the same time as the axial feed, after several passes to complete the thread processing , And finally the use of straight into the knife, to ensure the accuracy of the tooth angle of the thread.
C, left and right infeed method. In the ordinary lathe, this method is to use the horizontal trailer scale control thread turning tool vertical infeed, with a small drag plate scale control knife around the micro-infeed. When the thread is cut close, use a nut or thread gauge to check if the thread size and machining accuracy are acceptable. This method is easy to operate, so the application is wider.
Turning threads are generally used for larger diameter holes, and the workpiece can be firmly clamped on the lathe for rotary machining.
3, extrusion molding processing
Extrusion processing is no chip processing. The machining process, like tapping, squeezes the tap into the pre-drilled hole and extruds the material in the axial and radial directions to form a unique toothed thread profile. Thread extrusion is suitable for plastic deformation of the better material, the material range is relatively small, generally require the material elongation at break greater than 7%, while the maximum tensile strength of less than 1300N / MM. In the aluminum alloy processing in the most applications,
4, thread milling
Thread milling process as shown below, the thread end mill is generally first dropped to the bottom of the threaded hole, the use of spiral interpolation method close to the workpiece, along the screw hole after 360 degrees in the Z-axis direction after the rise of a pitch, and then leave the workpiece The The torque of the thread cutter is small, which increases the safety of the process. It also has a wide range of applicability, can process a variety of different materials, and in the same pitch, the use of a tool can be processed a variety of thread diameter or tolerance range of the thread. Disadvantages are: requires the machine is a coordinate CNC machine tools, and in addition to the tap, the processing efficiency is relatively low, the tool cost is relatively high, so it is suitable for small batch production of large diameter threaded hole processing.
