| 摘要 |
A process for cold forming semi-float axle tubes and similar types of metal tubes which includes arranging a short, tubular blank within an open ended die having an extrusion die throat, and pushing the blank through the die throat with a punch. The punch is provided with a ram portion, for applying pressure to the blank for moving it axially, and also an extension formed in several sections of successively smaller diameter which act as mandrels for sizing the tube interior walls. As the punch pushes the tube axially through the throat, initially a middle size extension is arranged within the throat to extrude a thickened leading edge portion on the blank. Further movement of the die results in a larger extension section traveling through the throat for extruding a thin wall tubular section of considerable length, leaving a small unextruded portion of the blank still within the die. At that point, the punch is removed and a second blank is inserted within the die. The punch is repositioned and presses the second blank against the unextruded portion of the first blank for continuing the extrusion thereof. Because of the spacing provided by the second blank, a smaller, end extension section is positioned within the throat for a short time for extruding a substantially enlarged inwardly extending ring portion on the partially extruded blank, followed by a thickened trailing end portion formed by the middle sized extension traveling through the die throat. While the trailing end thickened portion of the blank is formed, simultaneously the lead thickened end portion of the second blank is also formed. The cycle is repeated with successive blanks. The inwardly thickened lead end portion of each extruded tube is flared or flowed outwardly later, to form a generally bell-like enlarged end portion which is integral with the remainder of the tube, and of a wall thickness corresponding to the thickness of the trailing end thickened portion.
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