| 摘要 |
A continuous extrusion machine, in which feedstock is admitted (at 50) to a peripheral groove (12) in a rotating wheel (10), is enclosed in that groove by a cooperating shoe (24), and is frictionally dragged along the arcuate passageway (48) formed by said groove and a projecting portion (30) of said shoe towards an abutment (36) carried by the shoe. The pressure in the metal in front of the abutment continuously extrudes a metal product through a die (42). The abutment tip and adjacent wheel parts disposed downstream of the abutment are cooled directly by a jet of cooling fluid issuing from a nozzle (64) carried downstream on the shoe. An annular band (74) of a good thermally-conductive metal embedded concentrically in the wheel enhances the cooling obtained. Flash (68) extruded through clearance gaps (32, 34) between cooperating wheel and shoe surfaces is intercepted and broken off periodically, in short lengths, by teeth 70 projecting from the wheel. The radial depth of the passageway (48) progressively decreases in the direction of wheel rotation in a zone extending upstream from the abutment (36), so as to improve in that zone, in the case of particulate or comminuted feedstock, the metal flow pattern adjacent the abutment, such feedstock in that zone being in a fully compacted condition without voids. This is achieved by the shaping of a surface (40A) of a die block (40) which adjoins the abutment (36) and incorporates the die member (42). That shaping produces with particulate or comminuted feedstock a metal flow pattern closely resembling that achievable with feedstock in solid form. A continuous extrusion product (102) issuing from a continuous extrusion apparatus (10; 100) is threaded through a treatment die (104) whereby to change its cross-section, and is continuously drawn therethrough by a tensioning device (106, 112) under the control of a system which (a) senses the temperature of the product (102) as it leaves the extrusion apparatus (100); (b) converts a temperature signal (120) so produced, in a function generator (124), into a tension reference signal (126); (c) compares with that tension reference signal a tension feedback signal (116) derived from a sensor (118) adjacent the extrusion apparatus; and (d) controls the tensioning device in accordance with the difference of the tension reference and feedback signals so as to prevent the sensed tension in the product extending between the extrusion apparatus (100) and the treatment die (104) from exceeding a safe value which is less than the yield stress tension of that product at the sensed temperature. |
