| 摘要 |
1478204 Surface hardening of alloy steel articles K HEHL 12 July 1974 [16 July 1973] 30917/74 Heading C7N A method of heat-treating alloy steel workpieces, e.g. plastification cylinders and screws of injection moulding apparatus, comprises heating the workpiece to a temperature between 350‹C and the Ac 1 or Ac 3 points, e.g. 550‹-650‹C, followed by heating a surface above the Ac 1 or Ac 3 temperature and quenching to produce a hardened surface. The workpiece, e.g. cylinder 10, is clamped to a rotatable spindle 3 and inductors 7, 9 are in their uppermost positions. The medium frequency inductor 7 is lowered to the base of the cylinder 10, the generator 26 is switched on and the inductor 7 makes two successive passes to heat the cylinder. The inductor 7 is switched off, the high frequency inductor 9 lowered to the bottom of the cylinder, generator 22 is activated and the cylinder is heated from the inside. As the inductor 9 moves upwardly, a quenching spray exits from the spray head 8 and/or from annular spray head 6. The carriages 19, 23 carrying generators 22, 26 and the associated inductors 9, 7 are driven hydraulically, and the whole process may be automatically activated, e.g. by solenoid valves. |
