Libreng Kasanayan sa Inhinyero
Trial Weight Calculator para sa Pag-balance ng Rotor
Calculate the recommended trial weight mass for single-plane rotor balancing using an empirical field formula. Accounts for rotor mass, speed, correction radius, support stiffness, and vibration severity — and automatically caps the result so the trial-weight centrifugal force stays below 10% of the rotor weight.
Results
Formula ng Pagsubok na Timbang
The trial weight mass is estimated using an empirical field formula (based on Vibromera balancing experience, not derived from ISO 21940) that accounts for support conditions and vibration severity:
- Mt — masa ng pagsubok na timbang (g)
- Mr — masa ng rotor (g) — ilagay sa kg, na-convert sa gramo sa loob ng sistema
- Ksupp — coefficient ng tibay ng suporta (0.5–5.0)
- Kvib — coefficient ng antas ng vibration (0.5–3.0) — nakuha mula sa nasukat na vibration sa mm/s
- Rt — radius ng pag-install ng trial weight (cm) — ilagay sa mm, na-convert sa cm sa loob ng sistema
- N — bilis ng rotor (RPM)
Coefficient ng Tibay ng Suporta (Ksupp)
Ang coefficient na ito ay isinasaalang-alang kung paano nakakaapekto ang istruktura ng suporta ng makina sa vibration response sa unbalance:
| Ksupp | Support Type | Description |
|---|---|---|
| 5.0 | Very rigid | Masibong bloke ng kongkreto, matibay na istruktura ng bakal. Halos hindi nagbabago ang vibration sa unbalance — kailangan ng heavier pagsubok na bigat (mataas na Ksupp). |
| 4.0 | Rigid | Pundasyon ng kongkreto, matibay na pedestal. Karaniwang ginagamit para sa malalaking pump at compressor. |
| 2.0–3.0 | Medium | Karaniwang industrial na pagkakabit, baseplate sa kongkreto. Pinaka-karaniwang sitwasyon para sa mga fan, motor, at pangkalahatang makinarya. |
| 1.0 | Flexible | Spring mounts, rubber isolators. Ang makina ay umiibak nang libre — lighter pagsubok na bigat ay sapat (mababang Ksupp). |
| 0.5 | Very flexible | Suspended mount, soft isolators, balancing jig/cradle. Maximum na tugon ng vibration — pinakamahiwagang pagsubok na bigat. |
Tuntunin ng hinlalaki: Ang matibay na suporta (Ksupp = 4–5) ay “sumasalo” ng vibration, kaya kailangan ng mas mabigat na trial weight upang makagawa ng masusukat na pagbabago. Ang nababaluktot na suporta (Ksupp = 0.5–1) ay nagpapalaki ng tugon, kaya sapat na ang mas magaang na trial weight.
Vibration Level Coefficient (Kvib)
Ang coefficient na ito ay sumasalamin sa kasalukuyang kalubhaan ng vibration ng makina bago ang pag-balance:
| Kvib | Antas ng Vibrasyon | Condition |
|---|---|---|
| 0.5 | Maganda (≤ 1 mm/s) | Napakahusay na pagpapatakbo. Gumamit ng magaang na trial weight upang hindi malampasan ang vibration signal na mababa na. |
| 0.8 | Maganda (1–2 mm/s) | Malinaw na pagsasagawa. Lamang na pagpapayos. Magaan na pagsubok na bigat. |
| 1.0 | Katanggap-tanggap (2–3 mm/s) | Napapansin ngunit katanggap-tanggap na vibration. Pamantayan na balancing job. |
| 1.2 | Katanggap-tanggap (3–4.5 mm/s) | Katamtamang imbalance. Karaniwang umpukan. |
| 1.5 | Nakataas / Mataas (4.5–11 mm/s) | Malinaw at makabuluhang unbalance. Ang pinaka-karaniwang kaso sa field balancing — ang default na hanay. |
| 2.0 | Mapanganib (11–18 mm/s) | Malaking unbalance, agarang pag-balance. Maaaring gumamit ng mas mabigat na trial weight — mataas na ang vibration. |
| 2.5 | Mapanganib (18–28 mm/s) | Matinding unbalance. Katanggap-tanggap ang mas mabigat na trial weight upang matiyak ang masusukat na pagbabago ng vector. |
| 3.0 | Matinding (> 28 mm/s) | Labis na vibration. Suriin ang makina bago mag-balance; pinaka-mabigat na banda ng trial weight. |
Bakit Gumagana ang Formula na Ito
Ang formula na Mt = Mr × Ksupp × Kvib / (Rt × (N/100)²) ay sumasaklaw sa pangunahing pisika:
- Heavier rotors kailangan ng mas mabigat na trial weight (linear kasama ang Mr)
- Higher speeds nagbibigay ng mas malaking centrifugal force bawat gramo, kaya mas kaunting trial weight ang kailangan (inverse square ng N)
- Larger radius nangangahulugang mas malaking moment bawat gramo, kaya mas kaunting timbang ang kailangan (inverse ng Rt)
- Mas matibay na mga suporta kailangan ng mas maraming timbang upang makagawa ng matuklagang pagbabago ng vibration (mas mataas na Ksupp = 4–5)
- Mga flexible na suporta nagpapalaki ng tugon, kaya mas kaunting timbang ang kailangan (mas mababang Ksupp = 0.5–1)
- Mas mataas na umiiral na vibración nangangahulugan ng mas malaking umiiral na unbalance — proporsyonal na mas malaking trial weight (mas mataas na Kvib)
Centrifugal Force Safety Cap
The empirical formula alone can suggest a mass that is unsafe at speed — especially with high Ksupp and Kvib values. That is why the calculator always checks the centrifugal force the trial weight would generate:
- F — centrifugal force of the trial weight (N)
- m — trial weight mass (kg)
- r — installation radius (m)
- ω — angular speed (rad/s), N in RPM
A widely used field-balancing guideline is that this force should not exceed about 10% of the rotor weight (W = Mr × 9.81 N). If the empirical formula suggests a heavier mass, the calculator automatically limits the recommended trial weight to the 10%-of-rotor-weight force level and shows a warning. The centrifugal force of the recommended weight (in newtons and as a percentage of rotor weight) is always displayed in the results.
Praktikal na Halimbawa
Given: Mr = 111 kg = 111,000 g, N = 1111 RPM, Rt = 111 mm = 11.1 cm, Ksupp = 1.0, Vibration = 11 mm/s → Kvib = 1.5
Step 1: Speed factor: (N/100)² = (1111/100)² = 11.11² = 123.43
Step 2: Denominator: Rt(cm) × (N/100)² = 11.1 × 123.43 = 1,370.1
Step 3: Numerator: Mr(g) × Ksupp × Kvib = 111,000 × 1.0 × 1.5 = 166,500
Step 4: Empirical estimate: Mt = 166,500 / 1,370.1 = 121.5 g
Step 5 — force check: ω = 2π × 1111 / 60 ≈ 116.34 rad/s. For 121.5 g at 0.111 m: F = 0.1215 × 0.111 × 116.34² ≈ 182.6 N — that is ≈ 16.8% of the rotor weight (111 × 9.81 ≈ 1,089 N), above the 10% guideline.
Step 6 — safety cap: Mt(max) = 0.10 × 1,089 / (0.111 × 116.34²) ≈ 0.0725 kg = 72.5 g
Result: Gumamit ng humigit-kumulang 72 g trial weight at 111 mm radius (capped by the 10% force limit; the raw empirical estimate of 121.5 g would create excessive centrifugal force).
⚠️ Paalala sa Kaligtasan: An excessively heavy trial weight can cause dangerously high vibration. The goal of the trial run is a measurable but safe response — typically a 20–30% change in vibration amplitude or a 20–30° phase shift. Keep the trial-weight centrifugal force below about 10% of the rotor weight (this calculator enforces that limit automatically). If in doubt, start with half the calculated weight and increase gradually. Always ensure the trial weight is securely attached and cannot detach during rotation.
Paghahambing sa Pamamaraan ng ISO 21940
The classic ISO approach uses balance grade G to calculate permissible unbalance, then takes 5–10% of it (divided by the correction radius) as trial weight. This Vibromera formula is an empirical field shortcut, not an ISO-derived equation; it gives comparable results while directly accounting for real-world conditions (support stiffness and current vibration level) that the ISO method assumes are ideal. The added centrifugal-force cap keeps its recommendations within safe limits even when the machine is already vibrating heavily.
Mga propesyonal na instrumento at software para sa field balancing. Makamit ang pagsunod sa ISO 21940-11 sa lugar gamit ang mga device ng serye ng Balanset. Ginagamit sa 50+ na bansa.
