FIELD: method for building-up and foaming of polyolefin plates or films capable of building-up, or foaming of built-up polyolefin plates or films. SUBSTANCE: the moving, mainly continuously, polyolefin plate or film is blown round by hot air. Hot air counterflows the direction of movement of polyolefin plate or film along the latter. The device for building-up and foaming of polyolefin pates or films or for foaming of built-up polyolefin plates or films has and oven and a device for heating of the polyolefin plate or film placed in it, that is conjugate to the oven, by hot air. The device for heating the polyolefin pate or film is so positioned and made that the flow of hot air coming out of the device is directed approximately in parallel with the plane of the plate or film. The hot air counterflows the direction of movement of the plate or film passed through the oven. EFFECT: enhanced efficiency, especially when realized on a small scale, reduced expenditures connected with manufacture and operation. 13 cl, 2 dwg
