Method for fabricating a dielectric filled ferrite toroid for use in microwave devices

Abstract

The process provides practical manufacture of a two-piece, dielectric filled, ferrite toroid assembly while providing optimum electromagnetic characteristics presently not consistently available by manufacturing the toroid in a pressed one-piece configuration. A pair of complementary ferrite blanks of selected shapes are machined to dimension, and the mating surfaces thereof are selectively lapped. The complementary ferrite parts are then permanently assembled about a pre-machined dielectric insert, and the composite toroid is secured together by a selected adhesive selectively disposed therein.

We claim: 
     
       1. A method for fabricating a two-piece toroid having a dielectric material insert, which two-piece toroid exhibits the hystersis loop characteristics of a one-piece toroid, comprising the steps of: pressing selected quantities of a magnetic material into a pair of selected complementary blanks of substantially uniform density over their entire cross-sections;   machining the pair of blanks to define confronting mating surfaces commensurate with complementary cross-sectional shapes and lengths of given dimensions within selected tolerances;   lapping the confronting mating surfaces of the pair of machined shapes to a finish sufficient to maintain the hystersis loop characteristics inherent in a similar one-piece configuration formed of the same magnetic material;   machining a single dielectric material insert to outside dimensions which allow the insert to fit snugly within the complementary pair of magnetic machined shapes along the entire length thereof; and   assembling the complementary pair of machined shapes about the dielectric material insert with intimate contact between all surfaces of the insert facing respective confronting surfaces of the machined shapes, wherein the lapped confronting surfaces of the machined shapes are in such intimate contact that the hysteresis loop characteristics are similar to those of a one-piece toroid.   
     
     
       2. The method of claim 1 wherein the step of lapping provides surface finishes of from 1 to 10 microinches as required to maintain the hysteresis loop characteristics of a one-piece toroid of the same material. 
     
     
       3. The method of claim 2 wherein the step of pressing includes, pressing each of the complementary blanks to define rough forms of the given complementary cross-sectional shapes. 
     
     
       4. The method of claim 2 wherein the step of pressing includes, pressing the complementary blanks in the form of rough slabs of the magnetic material; and the step of machining the pair of blanks includes, grinding the slabs into the cross-sectional shapes of given dimensions. 
     
     
       5. The method of claim 2 wherein the magnetic material is a ferrite material. 
     
     
       6. The method of claim 5 further including the step of disposing selected adhesive on selected portions of the composite toroid to permanently secure the complementary pair of magnetic machined shapes in intimate contact at all surfaces thereof confronting the confined dielectric material insert. 
     
     
       7. The method of claim 6 further including the step of beveling the dielectric material along the corners thereof to allow disposition therealong of the selected adhesive. .Iadd. 8. A method for fabricating a two-piece toroid having a dielectric material insert, which two-piece toroid exhibits the hysteresis loop characteristics of a one-piece toroid, comprising the steps of;  machining a pair of complementary blanks of a magnetic material, with a substantially uniform density over the blanks' cross-sections, to define confronting mating surfaces on the blanks commensurate with the complementary cross-sectional shapes and lengths of given dimensions within selected tolerances;    lapping the confronting mating surfaces of the pair of machined shapes to a finish sufficient to maintain the hysteresis loop characteristics inherent in a similar one-piece configuration formed of the same magnetic material;   machining a dielectric material to form a single insert of outside dimensions which allow the insert to fit snugly within the complementary pair of magnetic machined shapes along the entire length thereof; and    assembling the complementary pair of machined shapes about the dielectric material insert with intimate contact between all surfaces of the insert facing respective confronting surfaces of the machined shapes, wherein the lapped confronting surfaces of the machined shapes are in such intimate contact that the hysteresis loop characteristics are similar to those of a one-piece toroid. .Iaddend. .Iadd. 9. The method of claim 8 wherein the step of lapping provides surface finishes of the order of 1 to 10 microinches commensurate with maintaining the hysteresis loop characteristics of a one-piece toroid of the same material. .Iaddend.