The four-line square thread is a non-standard thread and it is difficult to process. To this end, a forming turning tool that uses a cutting + extrusion method to Machine threads is designed and manufactured (see Figure 1). 1. Tool bar 2. Rear plate 3. Sliding support 4. Tool 5. Front plate The knife has the following characteristics: To accommodate the processing of large-aperture threads, the shank head is fitted with a sliding bearing. When the tool is fed radially, the shank can move in the flat hole of the sliding support. Since the sliding bearing keeps in contact with the inner hole during the cutting process, the rigidity of the tool bar can be enhanced and the vibration of the tool bar can be eliminated; The tool is the final finishing tool, the front corner portion of the two blades of the cutter head (about 3 mm) plays a cutting role, and the rear trimming portion acts as a squeeze light repairing function; The two side edges form a negative relief angle (width of about 0.5 mm) of about 1° during machining, so that the flank of the tool fits snugly against the thread surface of the workpiece, thereby reducing vibration and increasing the smoothness of the cutting. At the same time, it has a certain calendering effect, which can improve the surface quality of the workpiece; The top edge of the tool has a negative rake angle of 3°, so both side edges have a negative edge inclination of 3°, which can force the chips to flow toward the top edge during cutting, so that the processed surface is not scratched; The rear side edge (the top surface of the right edge) is ground with a crescent groove to increase the rake angle of the blade. When cutting, the working front angles of the two side edges tend to be equal, so that the cutting is smooth and the boring phenomenon is avoided. . When machining copper nuts, the workpiece rotation speed is 50r / min, and the cutting is performed by three knives: the first rough cutter width is 8mm, the front angle is large, and the feed amount is 1.5mm each time; the second rough cutter width is 15mm, the amount of feed is 1.5mm each time; the third is a precision cutter (see Figure 2), the width is 16+0.2mm, and the amount of feed is 3mm. figure 2 Before cutting, apply a knife to draw a groove on the workpiece, and the first knife is facing the middle of the groove to ensure that the balance on both sides is equal; the first cut and the one to be cut are single-sided force, resulting in the first buckle and finally In order to solve this problem, the size of the blank can be made slightly larger than the size of the workpiece, and then both ends are cut off. Stainless Steel Railing project Foshan City, Nanhai District Huidexing Stainless Steel Products LTD., , https://www.huidexing.net
6. Press the screw (M16) 7. Countersunk head screw (M10)
Figure 1 Four-line square thread forming turning tool structure 
Four-line square thread processing tool design (Figure)