Structural Safety Impact of Stamping Dies

Stamping dies are the primary process equipment for stamping processing, and stamped parts are produced through the relative movement of the upper and lower dies. During processing, the continuous opening and closing of the upper and lower dies poses a serious threat to the safety of operators if their fingers repeatedly enter or remain in the die closure area.

1. Working Components

   The punch and die are the working components directly responsible for forming the blank. As such, they are critical parts of the die. The punch and die are not only precise but also complex, and they must meet the following requirements:

   • Sufficient strength to avoid fracture or failure during the stamping process.
   • Appropriate material selection and heat treatment to prevent excessive hardness and brittleness.
2. Positioning Components

   Positioning components determine the installation position of the workpiece and include positioning pins (plates), stop pins (plates), guide pins, guide plates, pitch blades, side presses, etc. When designing positioning components, operational convenience should be considered. Over-positioning should be avoided, and positions should be easy to observe. It is preferable to use forward positioning, contour positioning, and guide pin positioning.

3. Blank Holding, Stripping, and Ejection Components

   Blank holding components include blank holders and pressure plates.

   Blank holders apply blank holding force to drawing blanks, preventing the blank from arching and wrinkling under tangential pressure. Pressure plates prevent the blank from shifting and bouncing. Ejectors and stripper plates facilitate part ejection and scrap removal. These components are supported by springs, rubber, or air cushion push rods on the equipment, allowing them to move up and down. Ejectors should be designed with sufficient ejection force, and their movement must be limited. Stripper plates should minimize the closure area or have hand clearance slots machined at operational positions. Exposed stripper plates should be surrounded by protective guards to prevent fingers or foreign objects from entering, and exposed edges should be chamfered.

4. Guiding Components

   Guide pillars and guide bushes are the most widely used guiding components. Their function is to ensure precise (clearance fit) between the punch and die during stamping. Therefore, the clearance between guide pillars and guide bushes should be smaller than the stamping clearance. Guide pillars are installed on the lower die base and must extend at least 5 to 10 mm above the top surface of the upper die plate at the bottom dead center of the stroke. Guide pillars should be positioned away from the die blocks and pressure plates to ensure operators can feed and retrieve materials without reaching over the guide pillars.

   
5. Support and Clamping Components

   These include upper and lower die plates, die shanks, punch and die holders, spacer plates, limiters, etc. The upper and lower die plates are the foundation components of the stamping die, with all other parts mounted and fixed on them. The planar dimensions of the die plates, particularly the front-to-back direction, should match the workpiece. Plates that are too large or too small may hinder operation.

   Some dies (such as blanking and punching dies) require spacer plates under the die set to facilitate part ejection. In such cases, the spacer plates should ideally be bolted to the die plates, and the thickness of the two spacer plates must be absolutely equal. The spacing between the spacer plates should be just enough to allow part ejection and not too large, as this could cause the die plates to crack.

6. Fastening Components

   These include screws, nuts, springs, dowel pins, washers, etc., which are generally standard parts. Stamping dies use a large number of standard parts. When selecting and designing these components, ensure they meet fastening and elastic ejection requirements. Avoid exposing fasteners on operational surfaces to prevent injuries and operational interference.