Bolt kuchlanish maydoni qanday hisoblanadi?

The tensile stress area As is calculated as As = (π/4) × ((d₂ + d₃)/2)², where d₂ is the pitch diameter and d₃ is the minor diameter of the external thread. This formula accounts for the thread root geometry and gives the effective cross-section for tensile loading per ISO 898-1.

O'rta diametr va kichik diametr o'rtasidagi farq nima?

O'rta diametr (d₂) — rezba tishi kengligi bo'shliq kengligi bilan teng bo'lgan diametr; u rezba mosligi uchun asosiy o'lcham hisoblanadi. Kichik diametr (d₃) — tashqi rezba ildizidagi eng kichik diametr. Kichik diametr boltning o'zak kesim yuzini belgilaydi.

Qo'pol va mayda qadamli rezba o'lchamlari o'rtasidagi farq nima?

For the same nominal diameter, fine pitch threads have a smaller pitch (P), resulting in a larger pitch diameter and minor diameter compared to coarse threads. This gives fine pitch bolts a larger stress area — for example, M12×1.25 fine has As ≈ 92 mm² versus M12 coarse (P=1.75) with As ≈ 84.3 mm². Fine pitch threads provide better resistance to loosening from vibration.

Muhandislik uchun bepul vosita

Metrik rezba o'lchamlari kalkulyatori

M3 dan M48 gacha bo'lgan metrik ISO rezbalari uchun barcha asosiy o'lchamlarni — o'rta diametr, kichik diametr, kuchlanish maydoni, o'zak maydoni — qo'pol va mayda qadam bo'yicha qidiring.

ISO 261 ISO 724 M3 – M48

Results

Rezba belgisi

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Nominal diametr d

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Pitch P

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O'rta diametr d₂

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Ichki diametr d₃ (bolt)

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Minor Diameter D₁ (nut)

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Rezba balandligi H

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Stress Area Aₛ

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Core Area A₃

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Thread	d (mm)	P (mm)	d₂ (mm)	d₃ (mm)	D₁ (mm)	H (mm)	Aₛ (mm²)	A₃ (mm²)

ISO Metrik Rezba Geometriyasi

Per ISO 261 and ISO 724, the basic profile of ISO metric threads is defined by the fundamental triangle height H₁ and the pitch P.

O'rta diametr & ichki diametr

Tashqi (bolt) rezbaning o'rta diametri d₂ va ichki diametri d₃ nominal diametr d va qadamdan P olinadi:

The minor diameter D₁ of the internal (nut) thread:

Kuchlanish maydoni & o'zak kesimi

Tortishish kuchlanishi maydoni A_s (ISO 898-1 ga muvofiq) va o'zak kesim maydoni A₃:

ℹ️ Note: Kuchlanish maydoni A_s — boltlarning tortishish va siqilish yuklamalarini hisoblashda qo'llaniladigan samarali ko'ndalang kesim maydoni. U o'zak kesim maydoni A₃ dan kattaroq, chunki qadamli va ichki diametrlarning o'rtacha qiymatini oladi.

Amaliy Misol

Misol — M12 yirik qadamli

Given: d = 12 mm, P = 1.75 mm

H = 0.866025 × 1.75 = 1.5155 mm

d₂ = 12 − 0.6495 × 1.75 = 10.863 mm

d₃ = 12 − 1.2269 × 1.75 = 9.853 mm

A_s = (π/4) × ((10.863 + 9.853)/2)² = 84.3 mm²

A₃ = (π/4) × 9.853² = 76.2 mm²