V-Bending Force
Calculate the force to bend a sheet in a V-die, F = (C·σ_r·L·t²) ÷ V, from the process constant C (~1.33 for free V-bending), the material tensile strength σ_r (N/mm²), the bend length L (mm), the sheet thickness t (mm) and the V-die opening V (mm). V-bending is the most common forming operation on press brakes: the sheet rests on a V-shaped die and a punch forces it in, bending it to the desired angle. Force grows with the SQUARE of thickness (thicker sheets need much higher forces) and with material strength, and decreases with die opening (larger V → lower force, but larger bend radius). The rule of thumb uses V ≈ 6-8 times the thickness. Computing the force is essential to select the press brake (tonnage) and not overload the tooling. The bend-tonnage tables ubiquitous in sheet shops are exactly this formula applied to combinations of thickness, material and die opening. Enter the constant, tensile strength, length, thickness and die opening.
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Força de dobramento em V
A força de dobramento de uma chapa numa matriz em V é F = (C·σ_r·L·t²) ÷ V, a partir da constante do processo C (~1,33 para dobra em V livre), da resistência à tração σ_r, do comprimento da dobra L, da espessura t e da abertura da matriz V. O dobramento em V é a operação de conformação mais comum em dobradeiras (press brakes): a chapa é apoiada sobre uma matriz em forma de V e um punção a força para dentro, dobrando-a no ângulo desejado. A força cresce com o quadrado da espessura (chapas mais grossas exigem forças muito maiores) e com a resistência do material, e diminui com a abertura da matriz (V maior → menor força, porém raio de dobra maior). A regra prática usa V ≈ 6 a 8 vezes a espessura. Calcular a força é essencial para selecionar a dobradeira (tonelagem) e para não sobrecarregar o ferramental. As tabelas de tonelagem de dobra, onipresentes nas oficinas de funilaria e estamparia (e nos controladores das dobradeiras CNC), são justamente a aplicação desta fórmula para todas as combinações de espessura, material e abertura de matriz. Informe a constante, a resistência à tração, o comprimento, a espessura e a abertura da matriz.
Related Tools
Cup Deep-Drawing Force
Calculate the deep-drawing force to form a cylindrical cup, F = π·d·t·σ_r·(D/d − 0.7), from the punch (cup) diameter d (mm), the sheet thickness t (mm), the material tensile strength σ_r (N/mm²) and the blank (disc) diameter D (mm). Deep drawing turns a flat disc into a hollow body (cup, can, pot, fuel tank, body panel): a punch pushes the disc center through a die, and the rim material flows radially inward, forming the cup wall. Force grows with the drawing ratio D/d (the larger the disc relative to the cup, the more material must flow and the higher the force), with material strength and thickness. The (D/d − 0.7) term is a classic empirical approximation (Siebel's formula) including friction and deformation work. Computing the force is essential to select the press and avoid RUPTURE of the cup bottom (if the force exceeds the already-formed wall's strength, the bottom tears). It is a central calculation in metal packaging, appliances and auto parts. Enter the punch diameter, thickness, tensile strength and blank diameter.
Punching Force (Sheet Cutting)
Calculate the force to punch (cut) a round hole in sheet metal, F = π·D·t·τ, from the hole diameter D (mm), sheet thickness t (mm) and the material shear strength τ (N/mm²). The product π·D is the cut perimeter; times thickness gives the area to be sheared; times shear strength gives the force. Punching (and sheet cutting in general, like blanking) is one of the most common stamping operations: a punch descends against a die, with a small clearance, and shears the material, separating the part or scrap. Computing the force is essential to select the press (whose tonnage capacity must exceed the force with margin) and to size the tooling. Force can be reduced with tricks like adding a shear angle to the punch or die, making the cut progressive instead of simultaneous over the whole perimeter — reducing the peak force (but increasing stroke). Knowing the force also lets you estimate the operation's work and energy. Enter the hole diameter, thickness and shear strength.
Minimum Bend Radius
Estimate a sheet's minimum bend radius, R_min = t·(50/r − 1), from the thickness t (mm) and the material's percent reduction of area r in the tensile test (%, a ductility measure). The minimum radius is the smallest inner radius you can bend a sheet to WITHOUT cracking the outer face (which is in tension). Bending below the minimum causes cracks or rupture in the outer fiber, where tensile strain exceeds the material's capacity. The minimum radius depends strongly on the material's DUCTILITY (here via reduction of area r): very ductile materials (annealed aluminum, low-carbon steels) can be bent to nearly zero radius (sharp bend), while brittle or work-hardened materials need large radii. It also depends on the bend ORIENTATION relative to the sheet's rolling direction (bending across the rolling direction allows smaller radii than along it, due to anisotropy). Knowing the minimum radius is essential in bent-part design: specifying a smaller radius than possible leads to crack scrap. It is common to express the minimum radius as multiples of thickness (e.g. '2t'). Enter the thickness and the material's reduction of area.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.