Square threads, characterized by a square thread profile, have a thread thickness equal to half the pitch. They offer high transmission efficiency but suffer from low alignment precision and weak root strength. Precise manufacturing of square threads is challenging, and the clearance after wear of the helical pair is difficult to compensate for or repair. A common example close at hand is the thread on a vise. It requires a great deal of force when tightening and loosening, which needs to be done frequently. Threads on valves and water pipes, regardless of size (small ones for faucets), are square threads, varying only in dimensions. Jacks and螺旋冲压机 also use this type of thread. Therefore, square threads are suitable for heavy loads, where the strength of the thread is required to be robust, and there are no stringent demands on thread precision.
Thread Turning Tools: Considering the shape of the thread, slotting tools are suitable for machining short threads. The width of the cutting edge should be half the pitch, and since there are many wide-pitch threads, high-speed steel flexible turning tools are often used. The biggest challenge in processing square threads is the grinding method of the turning tool. The width of the cutting edge should be half the pitch, which is not easy to operate. If the pitch and lead increase, the thread rise angle (lead angle) will be larger, and the back angle of the turning tool may hit the side of the thread. Additionally, for threads with a large lead, the thread rise angles at the top and bottom of the thread will not be the same. Therefore, on the outer circumference (thread top), the width of the cutting edge should be the same as the slot width, and at the bottom of the thread groove, the thread will be indented below. To avoid these phenomena, the indented part uses a trapezoidal turning tool with a smaller front cutting edge width.
Unlike triangular and trapezoidal threads, square threads do not have the complications of single or double cutting, nor is there an issue with the mid-径, because precision requirements are not high. In fact, this is relatively simpler in thread processing.
