METHOD OF MANUFACTURING HOLLOW ITEMS Russian patent published in 2010 - IPC C22F1/04 

FIELD: metallurgy.

SUBSTANCE: invention refers to manufacture of hollow items from aluminium alloys. Method involves fabrication of a hollow semi-finished product and heat treatment - ageing for the alloys strengthened with heat treatment, or annealing for the alloys non-strengthened with heat treatment. Heat treatment is performed in the device for heat fixing of external and/or internal surfaces of semi-finished product throughout its whole length or some part of length; at that, at heat fixing of external semi-finished product surface, as the device there used is sleeve made from steel with low thermal linear expansion coefficient with functional sleeve diametre calculated by the formula D_S≈D[1+(α_a-α_s)·t_H-α_a·α_s·t² _H], where D_S-functional sleeve diametre at normal temperature, D - outer diametre of semi-finished product at normal temperature, α_a - thermal linear expansion coefficient of aluminium alloy, α_s thermal linear expansion coefficient of steel from which sleeve is made, t_H - heating temperature of semi-finished product and sleeve at final heat treatment (°C). At thermal fixing of inner surface of semi-finished product, as the device there used is mandrel made from material with thermal linear expansion coefficient close to thermal linear expansion coefficient of semi-finished product metal with functional mandrel diametre calculated by the formula d ≤ d_m ≤ (d + 0.5 · Δd) , where d - inner diametre of semi-finished product at normal temperature, d_m - functional mandrel diametre at normal temperature, Δd - allowance for inner semi-finished product diametre.

EFFECT: improving geometric relationship of hollow items from aluminium alloys of any geometric shape.

2 dwg, 2 ex