Planetary gear extruder for processing plastics has planetary spindles whose sliding ends against a supporting ring are hardened by addition of weld material or by insertion of pins

摘要

The planetary spindles(10) slide on a supporting ring(11) at the rear end of the barrel(1) as they rotate around a central spindle(9). Wear resistance is increased either by hardening the sliding faces of the planetary spindles and/or supporting ring or by inserting pins into the planetary spindles. The hardened sliding faces are created by applying welding material onto the spindle base material, the welded material being harder than that of the spindles. Pin diameter is between one third and a half of the diameter of the root line of the planetary spindle teeth. Hardened faces have a hardness of not less than70HRC, preferably not less than80HRC. Welding material is applied to part of or the entire surface and is ground as required. Several layers of welding material may be built up, the first acting as a buffer layer. Deposited welding material has a thickness of 1-20mm, preferably 3-15mm and more preferably 10-14mm. Each layer is not >6mm, preferably 2-5mm and more preferably 3-4mm. Welding material may be introduced into bores in the base material of the planetary spindles(10). Such bores have a increasing diameter towards the open end. The increase may occur in steps or continuously. The angle at the outer end is 130-150[deg], preferably 110-130[deg]. Along the remainder of the bore the angle is 30-90[deg], preferably 50-70[deg]. After filling the bore the weld material is ground so that the new surface either projects above or is flush with the old surface.