The process of punching the solid blank into a capillary tube by extrusion method. There are two types of perforated capillary tubes: those with cup bottoms and those with penetrations, which are used as blanks for pipe jacking, pipe rolling by periodic pipe rolling machines, and pipe extrusion.
The pressure perforation achieved with the punch (head) on the press belongs to the extrusion deformation and can be divided into two types: open type and closed type, as shown in Figure 1.
When perforating, square billets (some use round billets) or polygonal ingots are often used.
If the punched metal just fills the free space between the barrel wall and the blank, the pressure piercing is open piercing. If the punched metal is larger than the volume of the free space, the pressure piercing is closed piercing.
When perforating polygonal steel ingots, it is usually open perforation at the beginning and closed perforation at the later stage.
An expansion perforation method is also widely used in the production of extruded steel pipes (Figure 2), that is, drilling a ф20~40mm pilot hole in the center of the blank, and then pushing the punch through the pilot hole to expand the pilot hole while making the hollow blank Extend backwards in the mold.
This method has high output, small perforation force, high capillary wall thickness accuracy, low cost, and can punch out longer capillary tubes, but it wastes a lot of metal.
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