Claims
- 1. Method of manufacturing a miniature variable inductor comprising a coil, a pair of connecting skids to which said coil is soldered, a movable ferromagnetic core, a screwthread on at least part of said core, an injection-molded plastics cover in the form of a hollow die with two oppositely disposed lateral walls to which said connecting skids are clipped, a solid part of said cover and a hollow space between said two walls, a central opening through said two walls, said solid part of said cover and said hollow space defining a housing for said core, and a resin encapsulating said coil, which is disposed in said hollow space coaxially with said central opening, which has a threaded portion where it passes through said solid part of said cover complementary to the thread on said core, which method comprises the steps of:
- making coils by winding conductive wire coated with a thermo-adherent insulative material in a warm air environment onto a temporary former and then removing said temporary former,
- making cores by overmolding grubscrews at one end of ferromagnetic rods the diameter of which is less than the diameter of said coils,
- making pairs of connecting skids by stamping them out from metal strip without separating them from said strip, so that said skids of a given pair are on opposite sides of said strip, facing each other across a distance the same as that between them in the finished inductor, said skids alternating with centering clips on said strip,
- injection molding plastics covers in the shape of a hollow die with two oppositely disposed walls the same distance apart as said skids of a given pair in said metal strip, each of said two walls being separated from the other by a solid part of said cover and a hollow space, a central opening matched to the dimensions of said core passing through said two walls and said solid part of said cover and being threaded in said solid part of said cover to complement said thread on said core, said hollow space being adapted to accommodate a winding coaxially with said central opening and said solid part of said cover being separated from said two lateral walls of said cover by grooves which expose the edges of said two walls,
- tinning and bending the ends of said coils,
- placing said coils on the pairs of connecting skids on said metal strip in the direction of its width and soldering their ends to said skids,
- placing said covers in a support having the same elongate shape as said metal strip and comprising a series of housings for said covers with the same spacing as said skids on said metal strip alternating with centering pins having the same relative disposition as said centering clips on said metal strip, each cover being disposed upside down with its central opening perpendicular to the length of said support,
- inserting said coils mounted on said pairs of connecting skids on said metal strip into said hollow spaces of said covers placed in said support, ensuring that said pegs locate correctly in said clips,
- placing a pin inside each housing of said support through a lateral opening coaxial with said central opening of said cover, said pin being shaped to define a space within which said core is to move,
- filling said hollow part of each cover with an encapsulating resin,
- removing said pin after said encapsulating resin has hardened,
- removing said covers from said support,
- separating said skids from said metal strip, and
- fitting said covers into said openings made by said pins.
Priority Claims (1)
Number |
Date |
Country |
Kind |
85 13918 |
Sep 1985 |
FRX |
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Parent Case Info
This is a division of application Ser. No. 902,832, filed Sept. 2, 1986, now U.S. Pat. No. 4,706,058.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4425702 |
Murakami et al. |
Jan 1984 |
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Divisions (1)
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Number |
Date |
Country |
Parent |
902832 |
Sep 1986 |
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