| 摘要 |
<p>Each mouthpiece aperture is formed by two sepd. semi-circular channel sections, each of which communicates through a centrally connected branch channel with the respective material inlet. Each of the semi-circular sections of the inner and outer mouthpiece channels has a successively diminishing axial length from the branch channel point of connection to the limit between the sections. - A sharp edge is arranged between the mouthpiece sections, and runs horizontally. The tool body is of tool steel, and is virtually cylindrical in shape. The inlets are at diametrically opposed points. At the one end surface of the tool body are two coaxial circular channels, an inner and an outer. The inner channel is defined between an inner and an outer cylindrical wall corresp. to the required wall thickness of the inner wall of the double-walled plastic pipe, and the outer channel is likewise defined in respect of the pipe outer wall.</p> |
