Process classification of stamping products

Process classification of stamping products

1. Basic process classification

Stamping processes can be divided into two categories based on their deformation properties: material separation and forming.

The separation process refers to the stamping process in which the stress in the deformed part of the billet reaches the tensile strength under the action of punching pressure, causing the billet to fracture and produce separation, thereby obtaining the required shape and size of the workpiece.

The forming process refers to the stamping process in which the stress in the deformed part of the blank reaches the yield point under the action of punching pressure, but does not reach the tensile strength, causing the blank to undergo plastic deformation without fracture and separation, thus obtaining the required shape and size of the workpiece.

2. Categories of Separation Processes

The separation process is divided into two categories based on its different deformation mechanisms: punching and trimming.

Blanking: Refers to the use of molds to cut sheet materials along a certain curve or straight line (including the following types)

Renovation is a separate processing method that reprocesses the cross-sectional part of a punched piece. Renovation deformation is a cutting mechanism, and the dimensional accuracy and cross-sectional quality of the workpiece are better than those of punched pieces.

3. Categories of forming processes

There are many forming processes, including bending, deep drawing, flanging, bulging, and extrusion processes.

Punching and cutting

1. Introduction to the Form and Forming Process of Blanked Products

The form of the punched product. The cross-section of the punched product is divided into four forms: collapse angle, bright zone, fracture zone, and burr. These four forms are generated at different stages, different parts, and different stress effects during the product punching process.

1) Elastic deformation stage

2) Plastic deformation stage

Stress analysis: The material's stress gradually exceeds the elastic limit from the edge to the center

3) Shear cracking stage

Stress analysis: The stress in the part of the material near the concave die edge first reaches the shear strength of the material, which increases the cracks generated by the material near the concave die edge. At this point, the material at the edge of the convex die is still in the plastic deformation stage. As the punch further penetrates into the material, the material near the punch also reaches shear strength and cracks occur. Later, the two cracks overlap and the material separates.

1. Classification, Function, and Structure of Blanking Products

Piercing

Function 1. Used as a general through-hole (with lower requirements); 2. Used as a self tapping bottom hole (product design requires a high proportion of bright bands); 3. Used as a high-precision shaft hole (requires no burrs and less fracture zone) (using mechanical deburring or mold chamfering)

Blanking and stamping

Function 1. Used as a general appearance (with lower requirements); 2. Used as a laser welding assembly for butt joints (without burrs, large bright bands, small gaps in fracture bands); 3. Used as a soft decorative support (requires curling or deburring)

Attention: 1. When designing the product, there should be appropriate rounded corners at the connections of each straight line or curve of the punched part (Otherwise, the stress of the concave mold is concentrated and it is easy to be damaged); 2. Considering the machining process of mold wire cutting, the minimum R angle of punched or dropped parts should not be less than R0.2.

Tongue cutting and curved lancing

Function 1. Used as a buckle; 2. Used as a limit; 3. Save processes, improve material utilization, and combine cutting and bending processes into one

Precautions for designing tongue cutting and curved cutting structures:

1) When cutting, the width of the punch should be large enough. When designing the parts, ensure that the distance between the cutting and bending parts is more than 5mm, otherwise the punch strength will be low and the lifespan of the mold will be affected.

2) When designing the mold, the cutting part of the blade should ensure a straight edge of about 3mm to prevent the occurrence of knife breakage. Ensure that there is a gap on both sides of the punch to ensure cutting before bending.