Stretching Die

Forming hollow parts: The core function is to transform straight metal sheet materials into open hollow parts, or to further change the shape and size of existing hollow parts.

Typical products: Include automotive fuel tanks, kitchen sinks, motor housings, beverage cans, and various metal cup-shaped containers.

Common mold classification: Depending on the combination of processes, they are divided into single-process molds and continuous molds.

Process comparison: Compared with progressive die stamping, the stretching process is more suitable for manufacturing components with large depths, cup-shaped or hollow shapes, while progressive dies are more suitable for flat hole parts.

Continuous stretching mold: Through the same set of molds multiple times on a strip material, the required shape is gradually formed, suitable for mass production.

Composite stretching mold: In one stroke, multiple processes such as blanking and stretching are completed simultaneously, suitable for high-precision and large-batch components.

Material selection has restrictions: Not all metals are suitable for stretching, and materials with good plasticity and moderate strength should be selected.

Recommended materials: Commonly used materials include stainless steel, low-carbon steel, aluminum, copper, and brass. These materials have excellent ductility and are less prone to cracking.

Avoid materials: Try to avoid using very hard or very brittle materials, as they are prone to chipping and have poor surface quality.

The stretching coefficient must be calculated accurately: The deformation degree of each stretching cannot be too large, and it should be controlled within the limit coefficient.

Calculation principle: The total stretching coefficient is equal to the product of each stretching coefficient. The thicker the material and the better the plasticity, the smaller the coefficient can be taken.

Number of times determination: If the product height is large, it needs to be stretched multiple times, and intermediate annealing treatment may be required to eliminate material hardening.

Mold structure details: The structural design directly affects the quality of the finished product and the lifespan of the mold.

Edge stopper design: When the material is thin and the depth is large, wrinkling is prone to occur, so an edge stopper should be added, but excessive pressure will cause cracking, and the pressure needs to be adjusted appropriately.

Ventilation hole setting: Ventilation holes with a diameter of 3mm or more should be set on the stretching punch to prevent the part from being difficult to remove when it is tightly attached to the punch.