| 摘要 |
<p>The arrangement is intended for applying a wear-resistant tubular lining to the inner surface of the housing bore containing the transport worm of an extrusion press. A cylindrical mandrel is first provided with an external wear- resistant deposit and machined so that it fits accurately in this bore. After insertion in the bore, the material of the mandrel is removed by a machining operation leaving the deposit in position. The final machining operation may remove a surface layer of the wear-resistant material. For a twin-screw extrusion press, two such mandrels may be coated and provided with flats so that they can together be inserted in the twin bores, after which the deposits are joined together and to the housing by soldering, preferably vacuum-soldering (at 11). Used for plastic extrusion press. This method overcomes the inadequacy of wear resistance produced by surface-hardening of the housing material of the bore wall. It also avoids stresses and deformation due to differential elasticity and differential expansion occurring when a wear-resistance insert bush is fitted by a material cast into the annular space between bush and bore wall. Such stresses and deformation lead to increased wear.</p> |
