The reasonable selection of tonnage for molds is crucial. Excessive tonnage can lead to waste, while choosing too little will hinder smooth mass production.
The reasonable tonnage can actually be calculated by adding up various forces in the mold to obtain the total sum, which will give the appropriate tonnage value.
Common forces in molds include: shearing force, blank holding force, stripping force, bending force, stretching force, etc.
Shearing force: the force that separates the material, accounting for the majority of all forces and serving as a core indicator for tonnage calculation. However, the shearing force is not constant, and the force changes significantly during the stamping process.
From the moment the punch contacts the material, the shearing force continuously increases until the material collapses at approximately 1/3T position to reach its maximum value, after which the material fractures and the shearing force decreases. When calculating the shearing force, only the maximum value needs to be considered.
Practical calculation of shearing force:
Formula: P = L * T * K
P: shearing force, unit in Newtons (N)
L: total shearing perimeter, unit in millimeters (mm)
T: material thickness, unit in millimeters (mm)
K: material shear resistance coefficient, unit in N/mm², common iron material coefficient is 330, stainless steel is 660
For example: for common iron material with thickness T = 1mm, and a total length × width to be sheared of 300×500, how should the shearing force be calculated?
Solution:
P = L * T * K
L = (300 + 500) × 2 = 1600mm
T = 1mm
K = 330
P = 1600 × 1 × 330 = 528000N ≈ 52.8t
Unit conversion: 1Kg = 9.8N ≈ 10N, 1t = 1000Kg ≈ 10000N
Practical calculation of bending force:
Formula: P1 = 0.43 * T * L1 * K1
P1: bending force, unit in Newtons (N)
L1: bending length, unit in millimeters (mm)
T: material thickness, unit in millimeters (mm)
K1: material tensile resistance coefficient, unit in N/mm², common iron material coefficient is 300~350, stainless steel is 350~400
(The calculation method is the same as above)
Practical calculation of blank holding force:
Formula: P2 = 0.33 * P1
P1: bending force, unit in Newtons (N)
Practical calculation of stripping force:
Formula: P3 = 0.05 * P1
P1: bending force, unit in Newtons (N)
Practical calculation of tonnage:
Formula: D = 1.3 * P / 10000
P: shearing force, unit in Newtons (N)
Note: 1.3 is the reserved tonnage and should not be calculated exactly.
Have you all calculated the tonnage for the mold press machine???
The reasonable tonnage can actually be calculated by adding up various forces in the mold to obtain the total sum, which will give the appropriate tonnage value.
Common forces in molds include: shearing force, blank holding force, stripping force, bending force, stretching force, etc.
Shearing force: the force that separates the material, accounting for the majority of all forces and serving as a core indicator for tonnage calculation. However, the shearing force is not constant, and the force changes significantly during the stamping process.
From the moment the punch contacts the material, the shearing force continuously increases until the material collapses at approximately 1/3T position to reach its maximum value, after which the material fractures and the shearing force decreases. When calculating the shearing force, only the maximum value needs to be considered.
Practical calculation of shearing force:
Formula: P = L * T * K
P: shearing force, unit in Newtons (N)
L: total shearing perimeter, unit in millimeters (mm)
T: material thickness, unit in millimeters (mm)
K: material shear resistance coefficient, unit in N/mm², common iron material coefficient is 330, stainless steel is 660
For example: for common iron material with thickness T = 1mm, and a total length × width to be sheared of 300×500, how should the shearing force be calculated?
Solution:
P = L * T * K
L = (300 + 500) × 2 = 1600mm
T = 1mm
K = 330
P = 1600 × 1 × 330 = 528000N ≈ 52.8t
Unit conversion: 1Kg = 9.8N ≈ 10N, 1t = 1000Kg ≈ 10000N
Practical calculation of bending force:
Formula: P1 = 0.43 * T * L1 * K1
P1: bending force, unit in Newtons (N)
L1: bending length, unit in millimeters (mm)
T: material thickness, unit in millimeters (mm)
K1: material tensile resistance coefficient, unit in N/mm², common iron material coefficient is 300~350, stainless steel is 350~400
(The calculation method is the same as above)
Practical calculation of blank holding force:
Formula: P2 = 0.33 * P1
P1: bending force, unit in Newtons (N)
Practical calculation of stripping force:
Formula: P3 = 0.05 * P1
P1: bending force, unit in Newtons (N)
Practical calculation of tonnage:
Formula: D = 1.3 * P / 10000
P: shearing force, unit in Newtons (N)
Note: 1.3 is the reserved tonnage and should not be calculated exactly.
Have you all calculated the tonnage for the mold press machine???
