The core process of the two-piece tinplate can involves transforming a round plate blank into a seamless can body with an integrated can body and can bottom through die stamping and stretching in one operation. In the manufacturing process of iron hammers, two main process routes are adopted:
Process route 1: Thinning and deep drawing (DI can)
This is the most widely used type in the beverage industry at present, and the process flow is as follows:
Sheet preparation → pre-drawing cup → second drawing → drawing and forming → flanging and necking
Specific steps:
1. Plate preparation: Punch and cut the tinplate into round billets with a thickness of 0.2-0.3mm, and apply lubricant on both sides
2. Pre-drawing cup: In the first drawing die, the blank holder is used to press the edge of the sheet metal, and the upper punch and lower punch work together to cause plastic deformation and flow in the circumferential direction of the sheet metal, resulting in the stamping of the sheet metal into a shallow can shape
3. Second deep drawing: Place the first can body in the second deep drawing mold for the second stamping and deep drawing process, resulting in a reduction in can body diameter and an increase in height
4. Deep drawing and flanging and necking: Perform the third stamping and deep drawing process, and set the flanging and necking at the can mouth position to a flaring structure
5. UV curing and no-cleaning: Through UV irradiation and ventilation, the paint film layer is cured, and the lubricant is fully evaporated, resulting in a finished tank product that requires no cleaning
After ironing, the wall thickness of the can body can be reduced from the original 0.3-0.4mm to 0.1-0.14mm, while the can bottom remains basically at the original thickness of the blank. This differentiated thickness distribution not only ensures the strength of the container, but also achieves material saving.
Process route 2: Deep drawing and drawing (DRD can)
It is suitable for producing shallow-drawn cans or containers with relatively special shapes. The basic process is as follows:
Original plate preparation → punching and cutting into corrugated plates → applying lubricant → cutting round sheet blanks → cupping → further punching and drawing → can bottom forming → flange trimming → inspection
Unlike ironing, the thickness of the can body remains essentially unchanged during deep drawing, with the material stretching primarily being compensated by the flow of metal at the flange.
The lid of a two-piece can
The lids of two-piece cans usually adopt standardized easy-to-open designs, which can be divided into three main types according to the opening method: pull-tab type, tab-retained type, and full-open type.
