Calculating the blanking force skillfully

1.

F impulse = KLT τ ， Where f -- blanking force, K -- coefficient; The safety factor is generally taken as 1.3 considering the wear of the cutting edge of the blanking die, the fluctuation of the clearance between the punch and the die (the variation or uneven distribution of the value), the lubrication condition, the variation of the mechanical properties of the material and the thickness tolerance, etc. L -- total length of blanking periphery, mm; T -- material thickness, mm; τ—— Material shear strength, MPa

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extended data:

stamping advantages

1. High proction efficiency, convenient operation, easy to realize mechanization and automation. This is because stamping depends on the stamping die and stamping equipment to complete the processing. The stroke times of ordinary press can reach dozens of times per minute, and the high-speed pressure can reach hundreds or even thousands of times per minute, and each stamping stroke can get a stamping part

2, stamping, stamping die ensures the size and shape accuracy of stamping parts, and generally does not destroy the surface quality of stamping parts, and the life of dies is generally longer. So stamping quality is stable, interchangeability is good, and has the same characteristics. p>

3. Stamping can process parts with large size range and complex shape, such as the second hand of clock and watch, the longitudinal beam and panel of automobile, and the cold deformation hardening effect of material ring stamping, the stamping strength and stiffness are higher

Stamping is a kind of material saving and energy-saving processing method, and the cost of stamping parts is low

3. Definition of blanking force:
refers to the maximum resistance of material to die ring blanking< Calculation formula of blanking force:
P = FLT σ B
where f is the empirical coefficient, generally 0.6-0.9; L is the length of the trimming line, mm; T is the sheet thickness, mm; σ B is the shear strength of plate, MPa
blanking:
it is a kind of stamping process in which a part of materials or process parts are separated from another part of materials, process parts or wastes by stamping die. Blanking is the general term for the separation processes such as shearing, blanking, punching, blanking, notching, cutting, chiseling, trimming, tongue cutting, cutting and repairing. A stamping method for separating a part or blank of a desired shape and size from a sheet metal. Blanking is to use the edge of the die to make the sheet proce shear deformation and separation along a certain contour line. Blanking accounts for the largest proportion in stamping proction. In the blanking process, the sheet metal itself does not proce plastic deformation except for the metal near the shearing contour line, so the parts processed by flat blanking are still the same

4. Calculation method of blanking force:
P = FLT σ B
where f is the empirical coefficient, generally 0.6-0.9; L is the length of the trimming line, mm; T is the sheet thickness, mm; σ B is the shear strength of plate, MPa
refers to the maximum resistance of the material to the die ring blanking.

5. Calculation formula of punch pressure P = KLT Г
where: K is the coefficient, generally equal to 1,
L is the circumference of the proct after stamping, in mm
t is the material thickness, in mm< br /> Г It is the shear strength of the material. Unit MPa
the calculated result is the unit of Newton. After dividing the result by 9800n / T, the result is the number of T.
this can only be calculated roughly. For the sake of safety, multiply the above value by 2, so the calculated value also conforms to the punching force calculation formula of compound die
P = k * L * t* τ
P flat edge blanking force (n)
tmaterial thickness (mm)
L blanking perimeter (mm)< br /> τ Material shear strength (MPA); K safety factor is generally k = 1.3.
calculation formula of punching shear force
F = s * L * 440 / 10000s workpiece thickness l workpiece length generally, this formula can be used
the punching pressure refers to the minimum pressure that the
press should have ring blanking
P stamping = P blanking + P unloading + P pushing + P blank holder force + P drawing force
the punch force is to select the tonnage of the punch press to determine the die strength. Stiffness check basis
1? Blanking force and its influencing factors: the main factors influencing the blanking force are as follows:
2. Calculation of blanking force P = Lt σ B
where p blanking - blanking force L - peripheral length of blanking part T - sheet thickness σ B-material strength limit σ The unit of result is kn
3? The force to unload the workpiece or scrap from the punch PX = kxp
where the reference number of KX - unloading force coefficient KX - is 0.04, and the calculated result unit is kn
4? The force to push the workpiece or scrap out of the die along the blanking direction Pt = ktpnkt - pushing force coefficient n - the number of pieces left in the die hole

6. It refers to the maximum resistance of the material to the die ring blanking.

7. Calculation formula of punch pressure P = KLT Г Where: K is the coefficient, generally equal to 1,

8. The calculation method of blanking force:
the blanking force is not less than the cutting force of cutting workpiece + pressing and returning force
cutting force = shear strength of material * cross-sectional area
taking a circle with a diameter of 100 mm cut on a 3 mm thick Q235 steel plate as an example, the calculation method is as follows:
cutting force of steel plate = 350 n / square mm * 3.14 * 100 * 3 = 329700 n
blank holder Return force: estimated 80000 n
press pressure: 32900 + 80000 = 409700 n
selected press: 63 t press