Folding Archimedes worm
The worm of Archimedes worm (ZA worm) is perpendicular to the plane of the worm axis (end face). The tooth profile is Archimedes spiral line (Figure Archimedes worm), and the tooth profile (the axial tooth profile) is linear on the plane containing the axis, and the tooth angle is 0=20. It can be used on the lathe straight edge pole (when the lead angle is smaller than 3 DEG when gamma knife (or double) when the gamma >3 degrees) turning. When the tool is installed, the top surface of the cutting edge must be passed through the axis of the worm, as shown in figure Archimedes worm. It is difficult to grind the worm, and it is inconvenient to be processed when the guide angle is large. See animation
Foldable straight profile worm
The tooth profile of the straight profile worm (ZN worm) is extended involute (drawing < straight profile worm >), and the N-N profile is a straight line. The ZN worm is also turning on a lathe with a single knife or double knife with a straight edge. The installation form of the tool is like diagram <; the straight profile worm >; It is also difficult to grind this worm. See animation
Folding involute worm
The involute worm (ZI worm) has a involute tooth profile (Figure < involute worm >), so it is equivalent to an involute helical gear with a small number of teeth (the number of teeth is equal to the number of worm heads) and the large helix angle. The ZI worm can be turned on the lathe with two straight blade blades. The top surface of the blade should be tangent to the base cylinder, one of which is higher than the axis of the worm, and the other is lower than the axis of the worm, as in Figure <; involute worm >; The tooth angle of the cutter should be equal to the spiral angle of the worm's base cylinder. The worm can be grind on a special machine tool. See animation
Folded conical loaf cylindrical worm
The cone loaf worm (ZK worm) is a kind of nonlinear spiral curved worm. It can not be machined on a lathe, only milling on a milling machine and grinding it on a grinder. In processing, in addition to the workpiece as a spiral motion, the tool also revolves around its own axis. At this time, the enveloping surface of the rotary surface of the milling cutter or grinding wheel is the spiral tooth surface of the worm (Fig. < cone, enveloping cylindrical worm >); the tooth profiles on I-I and N-N cross sections are all curvilinear (Figure <; cone enveloping cylindrical worm >). The worm is easy to grind, the worm's precision is high, and the application is more and more widely used.
As for the tooth profile of the worm wheel paired with the various kinds of worm, the tooth profile of the worm is completely different with the tooth profile of the worm. The worm wheel is usually machined on a hobbing machine with a hob or a flying knife. In order to ensure the worm and worm gear can engage correctly, the hob profile of the worm gear should be consistent with the profile of the worm, and the center distance between the worm and the worm should also be the same as the center distance of the worm drive.
