Jami Ruxsat Etilgan Qoldiq Nomutanosiblikni Ikkita Tekislik O'rtasida Qanday Taqsimlash Kerak
For a two-support rotor, the total permissible residual unbalance (U_{mathrm{per}}) is distributed between two correction planes based on rotor geometry and the rotor center of mass (CM) position. Below are the core rules from ISO 21940-11, including the 70:30 limitation set out in Clause 7.2.2 of the standard.
Definitions
- (U_{mathrm{per}}): total permissible residual unbalance for the rotor.
- (U_{mathrm{per}A}), (U_{mathrm{per}B}): permissible residual unbalance allocated to planes A and B.
- (L): A va B tekisliklari orasidagi masofa.
- (L_A): og'irlik markazidan A tekisligigacha bo'lgan masofa.
- (L_B): og'irlik markazidan B tekisligigacha bo'lgan masofa.
- Geometrik munosabat: (L = L_A + L_B).
1) Simmetrik rotor
Agar rotor simmetrik bo'lsa va massa markazi tekisliklar o'rtasida taxminan markazlashgan bo'lsa, ruxsat etilgan qiymatni teng taqsimlang:
(U_{mathrm{per}A} = U_{mathrm{per}B} = dfrac{U_{mathrm{per}}}{2})
Bu usul rotori simmetrikka yaqin bo'lgan ko'pchilik standart holatlarga mos keladi.
2) Nosimmetrik rotor (richag qoidasi)
Agar massa markazi bitta tayanch tomonga siljigan bo'lsa, ruxsat etilgan qiymatni richag qoidasi asosida taqsimlang, massa markazidan qarama-qarshi tekislikkacha bo'lgan masofaga mutanosib ravishda:
(U_{mathrm{per}A} = U_{mathrm{per}} cdot dfrac{L_B}{L})
(U_{mathrm{per}B} = U_{mathrm{per}} cdot dfrac{L_A}{L})
Bu yerda (L) — tekisliklar orasidagi masofa, (L_A) va (L_B) esa massa markazidan mos ravishda A va B tekisliklarigacha bo'lgan masofalar.
Muhim cheklov: 70:30 qoidasi
To avoid extreme accuracy requirements in one plane, ISO 21940-11:2016 (Clause 7.2.2) stipulates for inboard rotors — i.e. with the centre of mass located between the bearing planes — that the split shall be limited to a 70:30 ratio. Even if the CM is very close to one plane/support:
- The smaller share should not be less than (0.3 cdot U_{mathrm{per}}).
- The larger share should not exceed (0.7 cdot U_{mathrm{per}}).
(0.3 cdot U_{mathrm{per}} le U_{mathrm{per}A},, U_{mathrm{per}B} le 0.7 cdot U_{mathrm{per}})
Note: these limits apply to inboard rotors. For outboard (overhung) rotors, Clause 7.2.3 of the standard allows the larger share to reach (1.3 cdot U_{mathrm{per}}), while the smaller share must still be at least (0.3 cdot U_{mathrm{per}}).
Calculator
Enter (U_{mathrm{per}}) and distances. The calculator supports symmetric split and lever-rule split. It also applies the 70:30 limitation when enabled.
