ISO 1940-2 nima?

Quick Answer

ISO 1940-2:1997 (Mechanical vibration — Balance quality requirements of rigid rotors — Part 2: Balance errors) was the international standard for identifying, assessing and taking into account the errors that arise when balancing rigid rotors — from mandrel and drive-shaft unbalance to component runout and instrumentation scatter. It has been withdrawn and replaced by ISO 21940-14:2012 (Mechanical vibration — Rotor balancing — Part 14: Procedures for assessing balance errors), which extends the same procedures to rotors with flexible behaviour. Note: it is often confused with the balancing vocabulary — that is a different standard, ISO 21940-2 (formerly ISO 1925), whose terminology this page summarises below.

When an engineer in Germany specifies "dynamic unbalance correction to G 6.3 in two planes," a technician in Japan must understand exactly what is required — the same rotor condition, the same balancing procedure, and the same acceptance criterion. The ISO balancing vocabulary — ISO 21940-2 (formerly ISO 1925) — makes this possible by providing a single, internationally agreed vocabulary for the entire field.

ISO 1940-2 itself, by contrast, was neither a dictionary nor a tolerance specification — it dealt with balance errors. It classified the error sources of the balancing process as systematic (magnitude and angle can be evaluated — e.g. mandrel or drive-shaft unbalance, radial and axial runout, keys and keyways, residual magnetism, reassembly and instrumentation errors), randomly variable (loose parts, entrapped liquids, thermal distortion, windage) and scalar (only the maximum magnitude can be estimated, the angle is indeterminate — e.g. fitting clearances and manufacturing tolerances), and gave procedures for assessing them and taking them into account so that the residual unbalance genuinely stays within the permissible value Uper from ISO 1940-1 (now ISO 21940-11). Its successor, ISO 21940-14, keeps exactly this role within the ISO 21940 series.

Atamalarni Batafsil Tahlil Qilish

Qattiq / Egiluvchan Rotorlarni Farqlash

Bu balanslashtirish sohasidagi eng muhim tasnifdir. Ushbu farq hamma narsani belgilaydi: qaysi standart qo'llaniladi, qanday uskunalar kerak, nechta tekislik talab etiladi va balanslashtirish qanday tezlikda amalga oshirilishi kerak.

Rigid Rotor (ISO 21940-2 definition)

Istalgan ikkita ixtiyoriy tekislikda muvozanatsizligini tuzatish mumkin bo'lgan va tuzatishdan so'ng qoldiq muvozanatsizlik maksimal ish tezligigacha bo'lgan har qanday tezlikda sezilarli darajada o'zgarmaydigan rotor. Amaliy sinov: birinchi egilish rezonans chastotasi critical speed maksimal ish tezligidan ancha yuqori bo'lsa (odatda > 1,5× yoki undan ko'p), rotor qattiqdir.

Flexible Rotor (ISO 21940-2 definition)

Ish tezligida elastik deformatsiyaga uchraydigan va shu sababli muvozanatsizlik holati o'zgaRadigan rotor. Ikki tekislikdan ortiq sonda, ish tezligida yoki unga yaqin tezlikda balanslashtirilishi kerak. Applies to: katta turbogeneratorlar, ko'p bosqichli yuqori tezlikli kompressorlar, yuqori tezlikdagi uzun qog'oz mashinasi silindirlari. ISO 21940-12 standarti bilan tartibga solinadi.

Sanoat rotorlarining katta qismi — elektr motorlar, muxlislar, nasoslar, zamovniklar, vallar — qattiq rotorlardir. ISO 1940-1 G-sinf tizimi bevosita qattiq rotorlarga qo'llaniladi.

Muvozanatsizlikning Uch Turi

The vocabulary (ISO 21940-2) defines three fundamental types based on the geometric relationship between the principal inertia axis and the rotation axis. Understanding these is essential for selecting the correct balancing procedure:

Muvozanatsizlik vektori
U = m × r   (magnitude)     U∠θ   (polar form)
m = unbalanced mass (g) | r = distance from axis (mm) | θ = angular position (°)
  • Static unbalance produces a force — ikkala podshipnik ham 1× RPM chastotasida bir fazada tebranadi. Rotorni muvozanatsiz holda aniqlash mumkin — aylantirishsiz (og'irlik kuchi pichoq qirralarda buni ko'rsatadi). Bitta tuzatish tekisligi yetarli. Tor disk shaklidagi rotorlar uchun xos (L/D < 0.5): tor shkivlar, ventilyator krylchatkasi, yupqa flyuerviller.
  • Moment muvozanatsizligi produces a moment — bearings vibrate 180° out of phase at 1× RPM. The net force is zero (centre of mass is on the axis), but two equal and opposite heavy spots in different axial positions create a rocking couple. Only detectable while spinning. Requires two correction planes.
  • Dinamik muvozanatsizlik = static + couple combined. The general case for all real rotors that are not perfectly symmetric. Both force and moment are present. Bearings vibrate at 1× with neither in-phase nor exactly 180° out-of-phase relationship. Requires two-plane balancing.

Solishtirma muvozanatsizlik va G-daraja bog'liqligi

Solishtirma muvozanatsizlik (e = U/M) is the key metric that enables universal balance quality comparison. A 5 kg rotor with 50 g·mm unbalance has e = 10 µm. A 500 kg rotor with 5 000 g·mm unbalance also has e = 10 µm — identical balance quality despite 100× mass difference.

The G-grade extends this by incorporating speed: G = e × ω, giving a single number (mm/s) that characterises balance quality independently of both mass and speed. This is the foundation of the ISO 1940-1 tolerantlik tizimi.

Tuzatish tekisliklari va tolerantlik tekisliklari

The vocabulary draws a critical distinction that is often missed in practice:

  • Tolerantlik tekisliklari = tebranish va dinamik yuklamalar eng muhim bo'lgan podshipnik tekisliklari. Ruxsat etilgan muvozanatsizlik Uper shu yerda ko'rsatiladi.
  • Tuzatish tekisliklari = og'irlik qo'yish mumkin bo'lgan jismonan qulay joylar (ventilyator stupitsi, motor halqalari, val yelkalari). Ko'pincha podshipniklardan boshqa o'qli joylarda joylashgan.

Converting Uper tolerantlik tekisliklaridan tuzatish tekisliklariga o'tkazish uchun rotor geometriyasini bilish zarur. Assimetrik yoki tashqaridan osilgan rotorlar uchun bu o'tkazish har bir tekislik uchun tolerantliklarni sezilarli darajada o'zgartirishi mumkin. Balanset-1A rotor o'lchamlari kiritilganda bu konversiyani avtomatik ravishda bajaradi.

Muvozanatlash mashinalarining turlari

Ikki asosiy mashina turi turli fizik o'lchov tamoyillarini aks ettiradi:

  • Soft-bearing: Suspenziyaning tabiiy chastotasi ish tezligidan ancha past → mashina o'lchaydi displacement. Har yangi rotor uchun kalibrlash talab etiladi. Tarixiy ahamiyatga ega; hozirda kamroq qo'llaniladi.
  • Hard-bearing: Suspenziyaning tabiiy chastotasi ish tezligidan ancha yuqori → mashina o'lchaydi force. Doimiy kalibrlanган — har xil rotorlarni alohida kalibrlashsiz qabul qiladi. Zamonaviy asosiy tur.

Dala sharoitida muvozanatlash asboblari, masalan, Balanset-1A boshqa tamoyildan foydalanadi: ular ISO ma'nosida "mashina" emas, balki rotorning o'z podshipliklari va tayanchi o'lchov tizimi sifatida ishlatiladi; tuzatishni maxsus muvozanatlash mashinasisiz aniqlash uchun sinov og'irligi (ta'sir koeffitsienti) usulidan foydalanadi.

O'zaro havola: Har bir atama qayerda ishlatiladi

Standards That Reference the ISO Balancing Vocabulary (ISO 21940-2)

ISO 1940-1 / ISO 21940-11: Barcha tolerantlik va sifat atamalarini qo'llaydi — G-sinf, Uper, balans tolerantligi, qoldiq muvozanatsizlik. Ushbu lug'atning asosiy foydalanuvchisi.

ISO 14694: Uses rotor terms (rigid), unbalance terms, and extends with fan-specific BV application categories, balance grades and vibration-limit tables.

ISO 10816 / ISO 20816: O'lchov atamalarini qo'llaydi — tebranish tezligi, RMS, podshipnik korpusi o'lchov nuqtalari.

ISO 21940-12: Ko'p tezlikli, ko'p tekislikli protseduralar bilan moslashuvchan rotor ta'rifini kengaytiradi.

API 610 / API 617: Neft sanoati standartlari nasos va kompressor texnik shartnomalari uchun ISO 1940 G-sinflari va muvozanatsizlik terminologiyasiga murojaat qiladi.

ISO 1940-2 → ISO 21940-14: Transition

ISO 21940-14:2012 has formally cancelled and replaced ISO 1940-2:1997, of which it constitutes a technical revision — the main change being the extension of its applicability to rotors with flexible behaviour. The balancing vocabulary followed a separate path: ISO 1925 was revised as ISO 21940-2. The ISO 21940 numbering reflects integration into the comprehensive ISO 21940 series covering all aspects of rotor balancing. The old designations still appear widely in industry literature.


Rasmiy standart: ISO 21940-14:2012 (replaces ISO 1940-2) on ISO Store →

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