Deep Drawing Calculations and main principles of deep drawing with a hydraulic deep drawing press. Free consultation. Price from the manufacturer.
Deep Drawing Calculations
Deep drawing is a metal forming process used to form sheet metal into a desired shape. The process involves drawing a flat sheet of metal into a die cavity, using a punch. The sheet is then stretched and formed into the shape of the die cavity.
There are several calculations involved in the deep drawing process to ensure the final product meets the desired specifications. Some of the key calculations include:
- Blank size calculation: The size of the blank needed for deep drawing is calculated based on the desired diameter of the finished product, the depth of the draw, and the thickness of the material.
- Drawing force calculation: The force required to draw the material into the die cavity is calculated based on the size and shape of the die, the material properties, and the desired depth of the draw.
- Strain calculation: The strain on the material during the deep drawing process is calculated based on the initial and final dimensions of the material and the geometry of the die.
- Frictional force calculation: The force required to overcome the friction between the material and the die during the deep drawing process is calculated based on the coefficient of friction between the two materials.
- Punch force calculation: The force required to push the punch through the material during the deep drawing process is calculated based on the material properties and the geometry of the punch.
Overall, these calculations help ensure that the deep drawing process is carried out efficiently and effectively, resulting in a final product that meets the desired specifications.
Blank size calculation
Blank size calculation is an important aspect of deep drawing calculations, as it determines the amount of material required for the production of a specific part. The blank size is calculated based on the dimensions of the finished part, the material properties, and the desired thickness of the blank.
The basic formula for calculating the blank size is:
Blank Diameter (BD) = Finished Diameter (FD) + (2 x Depth of Draw (DOD))
where the depth of draw is the difference between the height of the blank before and after forming.
The blank size calculation also takes into account the material’s yield strength and its elongation at break, which are used to calculate the amount of deformation that can be achieved without cracking or tearing the material.
Other factors that can affect the blank size calculation include the type of tooling used, the press capacity, and the lubrication used during the drawing process.
Drawing force calculation:
Calculating the drawing force required for a deep drawing process involves several factors, including the material properties, the blank size and shape, the punch and die dimensions, and the friction between the material and the tooling.
One common equation used to calculate the drawing force is:
F = K * T * L * (S – L * R)
Where:
F = Drawing force (in pounds or newtons) K = Coefficient of drawing force (typically ranges from 0.5 to 0.6) T = Tensile strength of the material (in psi or MPa) L = Blank diameter or length (in inches or millimeters) S = Punch diameter or length (in inches or millimeters) R = Die radius (in inches or millimeters)
It’s important to note that this equation provides an estimate and may need to be adjusted based on specific process conditions and the desired level of accuracy. Additionally, other factors such as the material’s yield strength and work hardening behavior may also need to be considered. It’s recommended to consult with an experienced engineer or use specialized software to accurately calculate the required drawing force for a deep drawing process.
Strain calculation
In deep drawing, strain is the amount of deformation per unit length of the original material. It is an important parameter that determines the quality of the final product. The strain can be calculated using the following formula:
ε = ln (r/R)
Where:
- ε is the strain
- r is the radius of the punch
- R is the radius of the blank
The strain is directly proportional to the depth of the draw, which means that as the depth of the draw increases, the strain also increases. It is important to calculate the strain to ensure that the material does not exceed its elastic limit and cause defects in the final product.
Frictional force calculation
Calculating the frictional force is an essential step in determining the drawing force in deep drawing. The frictional force acts on the blank as it moves through the die and affects the drawing force required to form the blank into the desired shape. The frictional force depends on several factors, including the surface finish of the die, the material properties of the blank and die, and the lubrication conditions.
To calculate the frictional force, the coefficient of friction (µ) is required. The coefficient of friction is a dimensionless quantity that represents the ratio of the frictional force between two surfaces to the normal force acting perpendicular to those surfaces. The coefficient of friction can be determined experimentally or estimated based on empirical formulas.
Once the coefficient of friction is known, the frictional force can be calculated using the following equation:
Frictional force = µ x Normal force
where the normal force is the force acting perpendicular to the surface of the blank. The normal force is equal to the drawing force in deep drawing.
In summary, the frictional force can be calculated by determining the coefficient of friction between the blank and die surfaces and multiplying it by the normal force acting on the blank during the deep drawing process.
Punch force calculation
Punch force calculation in deep drawing involves determining the force required to punch the metal sheet into the desired shape. The punch force is determined based on various factors such as the size of the punch, the thickness of the sheet, the yield strength of the material, and the desired shape of the finished product.
The punch force can be calculated using the following formula:
Punch Force = (Shear Strength of Material x Perimeter of Blank) – (Blank Thickness x Drawing Force)
Here, the shear strength of the material is the maximum shear stress that the material can withstand before it starts to deform plastically. The perimeter of the blank is the length of the boundary of the blank, and the drawing force is the force required to pull the metal sheet through the die.
Once the punch force is calculated, it can be used to select an appropriate press machine for the deep drawing process. The press machine should be capable of providing the required punch force without exceeding its maximum capacity.