Общий каталог Widia 2017 - страница 698

Laydown Threading Shim Selection Guidelines

It is essential to select the correct shim to ensure thread quality and maximum tool life. These parameters are needed:

• Pitch
• Pitch diameter
• Number of starts
• Feed direction

NOTE: When considering method of thread cutting, the part’s shape and stability and the fl ow of chips are determining factors in your decision.

Laydown Selection Chart

pitch (mm) RH thread/RH tooling LH thread/LH tooling 10 — 9 — 8 — 7 — 6 — 5 — 4 — 3 — 2 — 1 — 0 — 1 — 2 — 3 — 4 — 5 — 6 — 7 — 8 — 9 — 10 — LH thread/RH tooling RH thread/LH tooling pitch (mm) NOTE: For multi-start threads, use the lead value instead of the pitch. Diagram of Thread Lead Angles To calculate the lead angle of a given thread, use this formula: All toolholders are designed with an inclination angle = 1.5°. When turning standard threads with a lead angle of 1–2°, this guarantees adequate ß = thread lead angle clearance at the fl anks of the insert’s thread tooth. The thread lead angle and the required De = effective pitch diameter of thread wear inclination angle of the insert are given by ß. P•S ß = Arctan P = 1/TPI / De Cutting edge height is constant at every shim TPI = threads per inch and insert combination. All toolholders are supplied with 1-1/2° lead angle. S = number of starts single-start, lead = pitch multiple-start, lead = pitch (x) number of starts