US3119917A

US3119917A - Induction heating device

Info

Publication number: US3119917A
Application number: US80628A
Authority: US
Inventors: Edward H Dehn
Original assignee: United States Steel Corp
Current assignee: United States Steel Corp
Priority date: 1961-01-04
Filing date: 1961-01-04
Publication date: 1964-01-28
Anticipated expiration: 1981-01-28

Description

Jan. 2s, 11964 E. HD1-:HN l3,119,917

INDUCTION HEATING DEVICE Filed Jan. 4, 1961 /NVE/V TOR EDWARD H. DEHN Allo/'nay United States Patent() 3,119,917 INDUCTEUN HEATING DEVICE Edward H. Dehn, (lil City, la., assigner to United States Steel Corporation, a corporation of New .lersey Filed dan. 4, 1961, Ser. No. 80,623 Il Claims. (Cl. 219-10.79)

This invention relates to an improved induction heating device.

Although my invention is not thus limited, the device is particularly useful in heat-treating ball valve cages used in oil well pumps, for example as shown in Neilsen Patent No. 2,294,568. A conventional ball valve cage includes a plurality of internal longitudinal ribs for guiding the ball closure member, and respective fingers at one end of each rib for limiting relative movement of the ball in that direction. Such cages are of small size, commonly having an inside diameter of less than 2 inches. Desirably the ribs and fingers `are hardened to resist wear which results from constant movement of the ball, but the remainder of the cage is left unhardened to promote toughness. lt is known to employ induction heating devices for selectively `heat-hardening the ribs and fingers, but previous devices with which I `am familiar heat only one rib and linger at a time. In structures of such small size, it has been considered impractical to heat ya plurality of ribs land fingers simultaneously for the reason that intermediate adjacent portions of the structure become overheated and lose toughness.

An object of the present invention is to provide an improved induction heating device which simultaneously heats a plurality of selected portions on the interior of a small metal article without overheating intermediate adjacent portions.

A further object is to provide an improved induction heating device which enables all ribs and lingers of a ball valve cage to be heated for hardening in a single operation without adverse effects on the remainder of the cage structure.

A further object is to provide a device which has the foregoing improved characteristics and is of simple construction readily used in existing manufacturing processes.

In accomplishing these and other objects of the invention, i have provided improved details of structure, a preterred form of which is shown in the accompanying drawing, in which:

FlGURE l is a perspective view, with parts broken away, of my improved heating device;

FIGURE 2 is a cross section of the device on line II-Il of FIGURE l;

`FIGURE 3 is an enlarged longitudinal sectional view of a ball valve cage of the type with which I can use my hea-ting device; and

FIGURE 4 is a cross section of the cage on line lV-iV of FIGURE 3.

As FIGURES l and 2 show, my induction heating device includes a substantially cylindrical core lll formed of a non-conducting ferromagnetic material. Such miaterials are available commercially, and consist of tine magnetic particles dispersed in a heat-resistant, electrically insulating binder, commonly plastic. An electrically conductive stern 12 is iixed to the core and extends upwardly therefrom. At least the upper portion of the stem is tubular, having a bore 13. An electrically conductive fitting 1-4 is iixed to the side of the stem above the core. One end of a continuous length of copper tubing 1S, preferably of square cross section, is joined to the iitting 14, which also provides communication between the bores of the tubing and stem. Tubing 15 has a convolution '16 which extends downwardly within 'a longitudinal groove 17 in the circumferential face of the core, forms an enlarged loop `1S at the bottom edge of the core, and thence Mice extends upwardly within groove 17 back to the top of the core. Next tubing 15 extends across the top of the core to one or more additional circumferentially spaced grooves 17a and 171), and it has convolutions which lie within these additional grooves with loops -at the bottom, similar to the arrangement illustrated for groove 17. The other end of tubing 15 is connected to a tubular auxiliary stem 19 of electrically conductive material. insulating inserts 20 separate the two lengths of tubing 15 which make up each. convolution 16, and an insulating sheath 2l covers the entire core and tubing to prevent direct shorts. l connect Istems l2 `and 19 to a suitable high frequency A.-C. source and also to suitable means for circulating water through the stems 'and tubing 15.

The particular induction heating device illustrated is designed for use with a valve cage constructed as shown in FIGURES 3 and 4. This cage has three

longitudinal ribs

22, 22a :and 22h spaced 120 apart around its inner circumference. Respective integral fingers 23 are formed at one end of each rib. To heat-harden the ribs and ingers, I insert the device within the cage and apply current to the stems 12 and 19 and also circulate water therethrough -to prevent overheating the tubing )15 and core lil. Each convolution 16 overlies `a

rib

22, 22a or 22h, and each loop 13 overlies a linger 23. The nonconducting magnetic core lll acts as an intensifier and is essential to attain eicient heating. The heating effect is concentrated at the ribs and iingers, which quickly reach critical temperatures for hardening, while intermediate adjacent portions of `the cage structure are not overheated. Following a brief heating step, I remove the device and quench the cage in any suitable known medium.

From the foregoing description, it is seen that my invention affords `a simple device for inductively heating a plurality of selected portions of the interior of a small metal article. The particular valve cage illustrated is only one example of the sort of article with which I can use the device. For other articles it is only necessary to construct the device of a size to lit the article and with the convolutions of the current carrying tubing matching the portions to be heated. In simultaneously heating all the portions to be hardened, -I `achieve a further advantage over heating them one at a time in that l do not destroy the hardening attained on one portion Iwhen heating another poition. I believe l have achieved a surprising and unexpected result in locally heating selected areas with-in a small confined space without encountering canceling effects.

While l have shown and described only a single embodiment of my invention, it is apparent that modifications may arise. Therefore, I do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

I claim:

l. An induction heating device for simultaneously heating a plurality of selected portions on the interior of a small metal article without overheating intermediate adjacent portions, said device comprising a substantially cylindrical core of non-conducting ferromagnetic material, a conductor having a plurality of convolutions which extend along the sides of said core, each convolution being circumferentially spaced from adjacent convolutions to concentrate heating of the article to portions which the convolutions overle, insulating material separating portions of said conductor making up the same convolution and covering said core and conductor, and means for applying high frequency electric current to said conductor.

2. An induction heating device for simultaneously heating a plurality of selected portions on the interior of a small metal article without overheating intermediate adjacent portions, said device comprising a substantially cylindrical core of non-conducting ferromagnetic material,

a tubular conductor having a plurality of convolutions which extend along the sides of said core, each convolution being circumferentially spaced from adjacent convolutions to concentrate heating of the article to portions which the convolutions overlie, insulating material separating portions of said conductor making up the same convolution and covering said core and conductor, means for applying high frequency electric current to said conductor, and means for circulating cooling Water through the bore of said conductor.

3. An induction heating device for simultaneously heating a plurality of selected portions on the interior of a small metal article without overheating intermediate adjacent portions, said device comprising a substantially cylindrical core of non-conducting ferromagnetic material, an electrically conductive tubular stem fixed to an end of said core, a tubular conductor electrically connected at one end to said stem with its bore in communication with the bore of said stem, said conductor having a plurality of convolutions which extend in series along the sides iof said core, each convolution being circumferentially spaced from adjacent convolutions to concentrate heating of the article to portions Which the convolutions overlie, an electrically conductive tubular auxiliary stem electrically connected to the other end of said conductor with its bore in communication with the bore of said conductor, insulating material separating portions of said conductor making up the same convolution and covering said core and conductor, means for applying high frequency electric current to said stems, and means for circulating cooling Water through the bores of said stems and said conductor.

4. An induction heating device for simultaneously heating a plurality of selected portions on the interior of a small metal article Without overheating intermediate adjacent portions, said device comprising a substantially cylindrical core of non-conducting ferromagnetic material having a plurality of circumferentially spaced longitudinal grooves in its sides, an electrically conductive tubular stem xed to the top of said core, a tubular conductor electrically connected at one end to said stem with its bore in communication with the bore of said stem, said conductor having a plurality of convolutions which extend in series, each convolution lying within a different one of said grooves and having an enlarged loop at the bottom edge of said core, each convolution being circumferentially spaced from adjacent convolutions to concentrate heating of the article to portions which the convolutions overlie, an electrically conductive tubular auxiliary stem electrically connected to the other end of said conductor with its bore in communication with the bore of said conductor, insulating material separating portions of said conductor making up the same convolution and covering said core and conductor, means for applying high frequency electric current to said stems, and means for circulating cooling Water through the bores of said stems and said conductor.

References Cited in the le of this patent UNlTED STATES PATENTS 2,749,423 Bisterfeld June 5, 1956 2,759,085 Van Iperen Aug. 14, 1956 2,777,041 Dustman Ian. 8, 1957 2,785,263 Van Iperen Mar. 12, 1957 2,825,788 Loving Mar. 4, 1958 2,828,397 Emerson Mar. 25, 1958 FOREIGN PATENTS 635,421 Great Britain Apr. 12, 1950

Claims

1. AN INDUCTION HEATING DEVICE FOR SIMULTANEOUSLY HEATING A PLURALITY OF SELECTED PORTIONS ON THE INTERIOR OF A SMALL METAL ARTICLE WITHOUT OVERHEATING INTERMEDIATE ADJACENT PORTIONS, SAID DEVICE COMPRISING A SUBSTANTIALLY CYLINDRICAL CORE OF NON-CONDUCTING FERROMAGNETIC MATERIAL, A CONDUCTOR HAVING A PLURALITY OF CONVOLUTIONS WHICH EXTEND ALONG THE SIDES OF SAID CORE, EACH CONVOLUTION BEING