| 摘要 |
The screw with a plurality of helix angles comprises a first section having a first thread with a first helix angle, at least one third section having a third thread with a third helix angle; and a fifth section having a fifth thread with a fifth helix angle wherein the fifth thread is identical to the first thread. The third helix angle is equal or not equal to the first helix angle. Moreover, the screw further comprises a second section connected between the first section and the third section; the second section having a second thread with a second helix angle; a fourth section connected between the third section and the fifth section; and the fourth section having a fourth thread with a fourth helix angle. A mold device for forming the screw is also included. The mold device further comprises a second mold line-symmetrical to the first mold. |
