Общий каталог Yamawa 2021 - страница 684

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13. Introduction to Thread Forming Taps (Roll Taps) Intro Shape of internal threads and ratio of thread engagement affected by bored hole diameter Compared with the basic height of thread engagement, the actual height of the thread engagement is called “thread engagement ratio” in SP percentage. Depending on the bored hole diameter, internal thread and thread engagement ratio will change. The tapping condition must be chosen by referring to the thread engagement ratio. The portion of material to be formed can be reduced by selecting the largest possible bored hole diameter. In this way the load on taps is reduced, decreasing tap’s wear and damage. SL Ck45, minor diameter of thread (cutting process) Aluminum, minor diameter of thread (forming process) PO M24x3 M25x2 minor diameter tolerance of internal thread minor diameter tolerance of internal thread Ø 20.752 - Ø 21.252 Ø 22.835 - Ø 23.210 Internal External [Aluminum, internal thread formed] Internal ST [Ck45 internal thread cut] M25x2 M24x3 thread thread thread bored hole size: Ø 23.903 bored hole size: Ø 20.652 minor diameter of finished internal thread : 22.723 mm minor dia tolerance of internal thread NG minor dia tolerance of internal thread NG thread engagement ratio: 103.1% thread engagement ratio: 105.2% ROLL [Aluminum, internal thread formed] [Ck45 internal thread cut] M25x2 M24x3 bored hole size: Ø 24.042 mm bored hole size: Ø 21.000 minor diameter of finished internal thread : 23.067 mm minor dia tolerance of internal thread: minor dia tolerance of internal thread : Middle CARBIDE Middle thread engagement ratio: 92.4% thread engagement ratio: 89.3% [Aluminum, internal thread formed] [Ck45 internal thread cut] M25x2 M24x3 bored hole size: Ø 24.240 mm bored hole size: Ø 21.352 minor diameter of finished internal thread : 23.462 mm LONG minor dia tolerance of internal thread NG minor dia tolerance of internal thread NG thread engagement ratio: 81.5% thread engagement ratio: 71.0% HAND Example of thread engagement for M6x1 cutting and forming tap TAPS Boring before tapping - Check 1 EG (STI) PD PD Engagement ratio on cutting taps Engagement ratio on roll taps Min Internal threads Min 100% Max 78.2% 100% SPECIAL THREADS, Internal threads Internal threads GAUGES Max THREAD Min Max 78.2% 74.1% MILLS Internal threads made by roll taps are different from those made by cutting Length of taps on the shape of minor diameter. engagement=9.1mm Engagement DIES Symbol classification Middle Coarse Engagement Fine length Internal threads Engagement Unit : mm length classification Unit : mm D1 d=6.0mm S Short engagement length 4H 5H — S≤3(mm) External threads *Hole size for thread forming taps Drill size Min Max M Normal engagement length 5H 6H 7H 3