| 摘要 |
<p>A die for mfr. of helically corrugated tubing by extruding a molten annular section tube through a cylindrical die fitted with a rotary lining featuring a helical channelled profile. The extrudate is vacuum sized and chilled as it slips through the lining, pref. assisted by a lubricant drip fed into the emerging profile to back feed over the interior of the die surfaces. After emerging from the die, the profile passes over a mandrel where external gripping by resilient rollers prevents radial twisting. An ancillary tool may perforate the extrudate at intervals along the root of the helix. Esp. for mfr. of semi-rigid or crush resistant pipes. esp. soil drainage pipes. Relatively simple machinery which produces continuous corrugated pipe faster and with few blemishes.</p> |
