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What is Archimedes worm?

Pubdate:2018-05-12 11:03:47   Hits:2046   【Large Moderate Small
What is Archimedes worm?

This worm, perpendicular to the axis of the plane (i.e. the end face), the tooth profile for Archimedes helix (TuArchimedes worm), in the plane containing the axis of the tooth profile (i.e. axial tooth profile) for a straight line, the tooth profile angle alpha 0 = 20 degrees. It can be machined on a lathe with a single knife with a straight edge (when the lead angle is less than 3 degrees) or with a double knife (when the lead angle is more than 3 degrees). When installing the tool, the top of the cutting edge must pass through the axis of the worm, as shown in the Archimedes worm. The worm is difficult to grind and is difficult to process when the lead angle is large. See animation normal straight profile worm (ZN worm) this kind of worm end face profile is extended involute (figure < normal straight profile worm >), normal surface (N-N) tooth profile is straight line. The ZN worm is also used for turning on the lathe with a straight blade single or double knife. The installation form of the tool is shown in Fig. This worm is difficult to grind up. See the animation involute worm (ZI worm) this kind of worm's end face profile is the involute (figure < involute worm >), so it is equivalent to a few teeth (number of teeth equals the number of worm heads), large helical angle involute cylindrical helical gear. The ZI worm can be turned on the lathe by two straight turning tools. The top of the blade should be tangent to the base cylinder. One cutter is higher than the worm axis and the other is lower than the worm axis, as shown in Figure <Involute Worm>. The tooth shape angle of the cutter should be equal to the base cylinder helix angle of the worm. This worm can be grind on a special machine tool. See animated cone enveloping cylindrical worm (ZK worm). This is a nonlinear helicoid worm. It can not be machined on the lathe. It can only be milled on the milling machine and grinded on the grinder. During machining, the cutter rotates around its own axis besides the spiral motion of the workpiece. At this point, the enveloping surface of the rotary surface of the milling cutter (or grinding wheel) is the spiral tooth surface of the worm (figure < conical enveloping cylindrical worm >), and the tooth profiles on the I-I and N-N sections are all curves (figure < conical enveloping cylindrical worm >). This worm is easy to grind. The worm has high precision and is widely used. As for the worm gear profile matched with the above worm, it is completely different from the profile of the worm. Worm gear is usually machined with hob or flying cutter on hobbing machine. In order to ensure that the worm and worm gear can mesh correctly, the hob profile of the cutting worm gear should be the same as the worm profile, and the center distance of the deep cutting should be the same as the center distance of the worm drive. Basic parameter modulus m, pressure angle, worm diameter coefficient q, lead angle, worm head number, turbine teeth number, crown height coefficient (take 1) and crown clearance coefficient (take 0.2). Among them, modulus m and pressure angle refer to the modulus and pressure angle of the worm shaft surface, that is, the modulus and pressure angle of the turbine end face, and are all standard values; the worm diameter coefficient q is the ratio of the worm indexing circle diameter to its modulus M.