TM — Trusted Machinery

這是一份將原文內容整理並轉譯為模具專業英文 (Die & Tooling Terminology) 的版本。文中採用了業界標準的術語，讓整體架構更加專業且條理分明。

Technical Overview of Deep Drawing Dies

A Deep Drawing Die is a specialized tooling assembly mounted on a press machine to transform a flat metal sheet blank into various open-formed hollow components (such as cylindrical, rectangular, spherical, or conical shapes).

1. Core Components & Working Principle

The basic mechanism involves press tonnage forcing the punch to press the blank—positioned on the die block—into the die cavity, inducing plastic deformation.

• Punch: Defines the internal geometry and dimensions of the drawn part.
• Die Block / Cavity: Defines the external geometry and dimensions of the part.
• Blank Holder (Pressure Plate): A critical component designed to clamp the metal sheet during draw-in, preventing wrinkling caused by compressive stresses in the flange area.

2. Mechanics of Deep Drawing

Unlike standard bending, deep drawing involves extensive material flow. As the punch descends, the blank under the blank holder flows inward toward the center of the die cavity, decreasing in diameter while increasing in wall height.

1. Elastic Deformation: Occurs upon initial contact between the punch and the blank.
2. Plastic Deformation (Material Flow): The core stage where the material flows into the die under combined radial tensile stress and tangential compressive stress.
3. Wall Formation: The drawn material along the cavity wall acts as a force-transmission zone, transferring punch force to the un-deformed flange section.

3. Classification & Variations

• First-draw vs. Redrawing Dies: If the draw depth is too deep for a single pass (risking rupture), multiple redrawing steps are used to progressively decrease the diameter and increase the depth.
• Reverse Drawing Dies: Draws the pre-formed shell in the opposite direction. This facilitates material flow, reduces work hardening, and allows higher draw ratios.
• Ironing Dies: Intentionally thins the sidewalls during drawing to produce parts with precise wall thickness (e.g., two-piece cans or cartridge cases).
• Single-Action vs. Double-Action Dies:
  • Single-Action: Used on standard presses; blank holding force (BHF) is supplied via die cushions, springs, or nitrogen cylinders.
  • Double-Action: Used on specialized double-action presses; the outer slide controls blank holding while the inner slide drives the punch, offering superior and controllable clamping force.

4. Critical Technical Parameters

• Drawing Ratio ($m$): A key indicator measuring the severity of deformation, defined as the ratio of the drawn shell diameter ($d$) to the initial blank diameter ($D$):$$m = \frac{d}{D}$$A smaller drawing ratio indicates greater deformation.
• Corner Radii (Punch & Die Radii): Crucial design factors. Too small a radius causes tensile fracture; too large a radius induces wrinkling.
• Lubrication: Due to intense sliding friction between the sheet metal and tooling surfaces, high-performance lubricants are essential to prevent galling (scoring) and tool wear.

5. Common Defects & Mitigation

• Wrinkling: Typically occurs in the flange area due to insufficient blank holding force or excessively thin material.
• Fracture (Tearing): Occurs at the “critical section” near the bottom radius when drawing forces exceed the ultimate tensile strength of the wall. This is usually caused by an excessively low drawing ratio or overly sharp tool radii.

Summary: A deep drawing die is a high-precision tooling system. Beyond defining part geometry, it relies on the precise management of blank holding pressure and material flow to successfully convert a flat sheet into a 3D hollow component.