中文版Thread: On the column or the circular cone surface, has the stipulation tooth shape continual bulge which forms along the spiral line.
Box thread: Thread which forms in the column or the circular cone internal surface.
External screw thread: Thread which forms in the column or the circular cone outside surface.
Effective thread: Screw which and the incomplete thread is composed of the complete thread, not including spiral tail.
Nominal diameter: On behalf of thread size diameter.
Great diameter: With external screw thread crest either in root of thread contacting ideal cylinder or circular cone diameter. (External screw thread) or D (box thread) expressed with d.
Pitch diameter: An ideal cylinder either the circular cone diameter, this column or the circular cone bus bar adopts in the tooth shape the trench and the bulge width equal place. This ideal cylinder either the circular cone are called the pitch diameter column or the pitch diameter circular cone. The pitch diameter (external screw thread) or D2 (box thread) expressed with d2.
Trail: With the outside root of thread either box thread crest contacting ideal cylinder or circular cone diameter. (External screw thread) or D1 (box thread) expressed with d1.
Pitch: The neighboring two teeth correspond the axial distances between two spots on the diameteral wire.
Thread precision: And turns on lathe by the thread tolerance zone gathers the weight thread quality overall target which the length is composed together.
Gyrotropic: The thread has the dextrorotation and the laevo-rotatory two kinds. The inside and outside threads turn on lathe fashionably, what turns on lathe clockwise into is the dextrorotation, what turns on lathe anti-clockwise into is the laevo rotatory.
