霸刀分享-常见螺纹加工方法的对比
螺纹切削:包括车削、铣削、攻丝、套丝、磨削、研磨和旋风切削等。车削和铣削螺纹时，工件每转一转，机床的传动链保证刀具或砂轮沿工件轴向准确而均匀地移动一个导程。攻丝或套丝时，刀具与件作相对旋转运动，并由先形成的螺纹沟槽引导着刀具(或工件)作轴向移动。
螺纹铣削:在螺纹铣床上用盘形铣刀或梳形铣刀进行铣削。梳形铣刀用于铣削内、外普通螺纹和锥螺纹，由于是用多刃铁刀铁削，其工作部分的长度又大于被加工螺纹的长度，故工件只需要旋转1.25~1.5转就可加工完成，生产率很高。螺纹铣削的螺距精度一般能达8~ 9级，表面粗糙度为R5~0.63微米。 这种方法适用于成批生产-般精度的螺纹工件或磨削前的粗加工。
螺纹磨削:主要用于在螺纹磨床上加工淬硬工件的精密螺纹，按砂轮截面形状不同分单线砂轮和多线砂轮磨削两种。单线砂轮磨削能达到的螺距精度为5~6级，表面粗糙度为R1.25~0.08微米，砂轮修整较方便。这种方法适于磨削精密丝杠、螺纹量规、蜗杆、小批量的螺纹工件和铲磨精密滚刀。多线砂轮磨削又分纵磨法和切入磨法两种。
螺纹研磨:用铸铁等较软材料制成螺母型或螺杆型的螺纹研具，对工件上已加工的螺纹存在螺距误差的部位进行正反向旋转研磨，以提高螺距精度。淬硬的内螺纹通常也用研磨的方法消除变形，提高精度。
攻丝和套丝:攻丝是用一定的扭距将丝锥旋入工件上预钻的底孔中加工出内螺纹。套丝是用板牙在棒料(或管料)工件上切出外螺纹。加工内，外螺纹的方法虽然很多，但小直径的内螺纹只能依靠丝锥加工。攻丝和套丝可用手工操作，也可用车床、钻床、攻丝机和套丝机。
螺纹滚压:用成形滚压模具使工件产生塑性变形以获得螺纹的加工方法。螺纹滚压一般在滚丝机、搓丝机或在附装自动开合螺纹滚压头的自动车床上进行，适用于大批量生产标准紧固件和其它螺纹联接件的外螺纹。滚压螺纹的外径一般不超过25毫米，长度不大于100毫米，螺纹精度可达2级(GB197-63),所用坯件的直径大致与被加工螺纹的中径相等。
A comparison of common thread processing methods
Thread cutting: including turning, milling, tapping, threading, grinding, lapping and cyclone cutting, etc. When turning and milling threads, with each revolution of the workpiece, the transmission chain of the machine tool ensures that the cutting tool or grinding wheel moves accurately and evenly along the axial direction of the workpiece by one lead. When tapping or threading, the tool and the workpiece perform relative rotational motion, and the tool (or workpiece) is guided to move axially by the previously formed thread groove.
Thread milling: Milling is carried out on a thread milling machine using a disc milling cutter or a comb milling cutter. Comb milling cutters are used for milling both internal and external common threads and conical threads. As they are made with multi-edge iron cutters and the length of the working part is greater than that of the thread being processed, the workpiece only needs to be rotated 1.25 to 1.5 times to complete the processing, resulting in a very high productivity. The pitch accuracy of thread milling can generally reach grade 8 to 9, and the surface roughness is R5 to 0.63 microns. This method is suitable for batch production of thread workpieces with general precision or rough machining before grinding.
Thread grinding: It is mainly used for processing precision threads of hardened workpieces on thread grinding machines. According to the different cross-sectional shapes of the grinding wheel, it is divided into single-line grinding wheel and multi-line grinding wheel grinding. The pitch accuracy that can be achieved by single-line grinding wheels is 5 to 6 grades, and the surface roughness is R1.25 to 0.08 microns. The grinding wheel dressing is relatively convenient. This method is suitable for grinding precision lead screws, thread gauges, worms, small batches of threaded workpieces and scraping precision hobs. Multi-wire grinding wheels are further divided into longitudinal grinding and plunge grinding.
Thread grinding: A thread grinding tool made of relatively soft materials such as cast iron in the shape of nuts or screws is used to rotate and grind the parts of the processed threads on the workpiece that have pitch errors in both forward and reverse directions to improve the pitch accuracy. Hardened internal threads are usually ground to eliminate deformation and improve precision.
Tapping and threading: Tapping involves using a certain torque to rotate a tap into a pre-drilled bottom hole on a workpiece to produce internal threads. Threading is the process of cutting external threads on bar (or tube) workpieces using dies. Although there are many methods for processing internal and external threads, small-diameter internal threads can only be processed by taps. Tapping and threading can be operated manually or by lathes, drilling machines, tapping machines and threading machines.
Thread rolling: A processing method that uses a forming and rolling die to cause plastic deformation of the workpiece to obtain threads. Thread rolling is generally carried out on thread rolling machines, thread rolling machines or automatic lathes equipped with automatic opening and closing thread rolling heads. It is suitable for the mass production of external threads of standard fasteners and other threaded connections. The outer diameter of rolled threads generally does not exceed 25 millimeters, and the length does not exceed 100 millimeters. The thread accuracy can reach grade 2 (GB197-63), and the diameter of the blank used is approximately equal to the median diameter of the thread to be processed.