Patent GB-789419-A (GB)
Title: Improvements in or relating to sharpening or polishing apparatus
Inventor: SIMJIAN LUTHER GEORGE
IPC: H01F7/06
Filed: 1956-02-03
Abstract: 789,419. Sharpening or polishing. REFLECTONE CORPORATION. Feb. 3, 1956, No. 3541/56. Class 60. Sharpening or polishing apparatus comprises a mixture of a liquid, non-magnetic abrasive particles and magnetic particles in a container which is arranged to surround the portion of an article to be treated, means for supporting the article in the mixture, and means applying a varying magnetic field to the mixture to vary the consistency thereof. Apparatus for sharpening a cutting instrument, e.g., a surgical knife blade 13, Fig. 1, comprises a container 10 in which is a mixture of magnetic particles such as iron filings abrasive particles such as carborundum, and a liquid such as a light oil. The pole pieces of a magnetic core 12 having a winding 20 project through the container walls so as to be adjacent the cutting edge of the knife blade 13. A holder 14 for the knife blade is coupled to an armature 15 controlled by an electromagnet having a core 17 and winding 18. Direct current is supplied from a rectifier 21 to the windings 18, 20 under the control of commutators 23, 24 driven by an electric motor 26, to produce the following cycle (1) windings 18, 20 not energized : the knife blade 13 is in its lowest position, and the mixture has a low consistency. (2) winding 20 energized : the mixture has a high consistency. (3) winding 18 also energized : the knife blade is moved upwardly through the high consistency mixture. (4) winding 20 deenergized ; the mixture has a low consistency. (5) winding 18 also de-energized : the knife blade is moved downwardly by a spring 34. The cycle is repeated as often as necessary. In a modification, Fig. 2, the support 14 for the instrument 13 is attached to a pivoted arm 35 which is rocked by a cam 37 on the shaft of the commutator 38 which controls supply to the winding 20 from a D.C. source 42. In a further modification, Fig. 3, winding 20 is connected to A.C. source 22 through a phase changing circuit including an inductor 44 and a capacitor 45 either one or both of which may be adjustable; the instrument 13 is secured to a pivoted arm 46 controlled by a magnet 47 fed from the A.C. source. In a further modification, Fig. 4, a gear 50 to be polished is mounted within the bath and is secured to shaft 51 rotated through worm gearing 52 by motor 53. When current is supplied to winding 20 the mixture has its consistency altered cyclically thus giving the magnetic particles a slight vibratory motion which is imparted to the abrasive particles thereby polishing that portion of the gear 50 which lies in the vicinity of the pole pieces of the core 12. By slowly rotating the gear, the entire periphery is polished. In a further modification, Fig. 5, for polishing an irregular object two sets of three pole pieces are employed together with switching means 54 for periodically switching from one set to the other ; the switching means may be a relay operated device or a commutator mechanism run by a motor. At one interval of time coils 55, 56, 57 are connected together in the three phase relationship with supply lines 58 ; after a few cycles, the device 54 switches the current to coils 60, 61, 62. The pole pieces of one set of coils are mounted in a different plane from the pole pieces of the second set, and each set produces a magnetic pattern different from the pattern produced by the other set. The magnetic flux from either one of the sets of coils produces a vibratory motion within the mixture which is circular in character ; the consistency of the mixture in front of any set of pole pieces varies as a function of the instantaneous magnetic flux density and flux pattern.