How to calculate the force needed for steel plate stamping

1. Look at the materials of the book, to see the steel plate material, pressing method
the width of the sheet is 500-1500 mm; The thickness is 600-3000 mm. According to the types of steel, there are ordinary steel, high-quality steel, alloy steel, spring steel, stainless steel, tool steel, heat-resistant steel, bearing steel, silicon steel and instrial pure iron sheet; According to professional use, there are oil barrel plate, enamel plate, bulletproof plate, etc; According to the surface coating, there are galvanized sheet, tinplate, lead plate, plastic composite steel plate, etc.

2. For separation process:
calculation of punching force

in blanking process, punching force refers to the general term of
, unloading force, pushing force and pushing force. Punching force is the main basis for selecting
and also the necessary data for die design<

1.
calculation

is the pressure exerted on the sheet by the punch in the blanking process, which changes with the depth of the punch into the material. The blanking force F can be calculated as follows:
F = KLT τ
where f -- blanking force, N
k -- coefficient; Considering the wear of
cutting edge, fluctuation of clearance between punch and die (variation or uneven distribution of values), lubrication, variation of
and thickness tolerance and other factors,
is generally set as 1.3
L -- total length of blanking periphery, mm
T -- material thickness, mm< br /> τ—— Material
, MPa
when
cannot be found τ It can be used
σ B substitute τ， In this case, the approximate calculation method of k = 1 is adopted. That is,
F = Lt σ B
where σ B -- material
, MPa

2. Calculation of unloading force, pushing force and pushing force
after blanking, the force required to scrape the material from the punch is called unloading force; The force required to push the part or scrap from the die is called pushing force; The force required to eject the part from the die is called ejecting force. In the actual proction, it is generally calculated as follows:
unloading force F = k unloading f punching
pushing force F = NK pushing f punching
pushing force F = k jacking f punching
where f punching -- blanking force, N
k unloading - unloading force coefficient, whose value is shown in the table
k push -- push force coefficient, whose value is shown in the table
k top -- the force coefficient of the top part, whose value is shown in the table
n -- the quantity of parts or scrap accumulated in the die (n = H / T); H is the height of the straight edge; T is the material thickness.

3.

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

4. Check Q235's shear strength in the stamping manual, which is about 32 ~ 38 kggm2, and multiply the cross section by 200x4x10x38 = 304t

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. Generally, the unit of MPa is 320.
the unit of calculation is Newton. When the result is divided by 9800n / T, the number is t.
this can only be calculated roughly. For the sake of safety, multiply the above value by 2, so that the calculated value also conforms to the impact pressure of the composite die

6. F=LT σ BF
L refers to the length of the trimming line. For example, if a square hole is punched, the length of the trimming line is the sum of the lengths of the four sides of the square hole, which is just its perimeter
t refers to the material thickness, unit: mm
F is the blanking coefficient, generally 1.3
F is the blanking coefficient σ B refers to the tensile strength of stamping steel plate material
this formula is the punching force calculation formula of punch press.

7. The area of the stamping part of the iron plate, multiplied by the yield strength of the stamping plate, is the required force, multiplied by the safety factor of 1.1.5, unit: n, divided by 10000, to obtain the tonnage of the press

8.

σ= Fb/So

in the tensile process, the material enters the strengthening stage after the yield stage, and then the maximum force FB is obtained by dividing the original cross-sectional area so of the sample with the decrease of the transverse section size σ， It is called tensile strength or strength limit σ b. The unit is MPa. It represents the maximum ability of a metal material to resist failure under tension. The calculation formula is as follows: σ= Fb/So

when the steel yield to a certain extent, e to the rearrangement of internal grains, its resistance to deformation increases again. At this time, although the deformation develops rapidly, it can only increase with the increase of stress until the stress reaches the maximum. After that, the ability of steel to resist deformation is obviously reced, and a large plastic deformation occurs at the weakest point, where the cross section of the specimen shrinks rapidly, necking phenomenon occurs, and finally fracture occurs

(kilogram force per unit area)

in China, the universal material testing machine is widely used to measure the tensile / compressive strength of materials

for brittle materials and plastic materials without necking, the highest tensile load is the fracture load, so the tensile strength also represents the fracture resistance. For necking plastic materials, the tensile strength represents the resistance to the maximum uniform deformation and the ultimate bearing capacity of the material under static tension. For parts such as wire rope, tensile strength is a significant performance index. Tensile strength is easy to measure and has good reprocibility. It has a certain relationship with other mechanical properties such as fatigue limit and hardness. Therefore, it is also used as one of the conventional mechanical properties to evaluate proct quality and process specification

9. The actual force required is a little smaller than the calculated one, because the punching needle is inclined. Manual punch needle drop speed, may also be labor-saving factors.