US2452162A

US2452162A - Induction heating coil

Info

Publication number: US2452162A
Application number: US614688A
Authority: US
Inventors: Robert J Stanton; Lowry Christopher
Original assignee: Induction Heating Corp
Current assignee: Induction Heating Corp
Priority date: 1945-09-06
Filing date: 1945-09-06
Publication date: 1948-10-26
Anticipated expiration: 1965-10-26

Description

Oct. 26, 1948.- R. J. STANTON ETAL INDUCTION HEATING 0011.

Filed Sept. 6, 1945 mv ENT'OFZS Pose/2T J 5 TA/vTo/v CHRISTOPHER LOVYFZY 7W GW MM? AT TO RN EYS Patented Oct. 26, 1948 UNITED STATES PATENT OFFICE INDUCTION HEATING COIL of New York Application September 6, 1945, Serial No. 614,688

1 Glaim. 1

This invention pertains to an induction heating coil of novel construction, particularly adapted for use in uniformly hardening the face portions of internal combustion engine rocker arms and other metal objects of analogous configuration.

Owing to the peculiar shape of internal combustion engine rocker arms and the like, extreme difficulty has been encountered in devising means for so heating the face portions thereof by means of high frequency induced currents, as to provide a uniform hardness pattern over the face portion on subsequent quenching. The present invention provides a high frequency induction coil construction which is ideally adapted to such purposes.

In accordance with its preferred embodiment, the coil of the present invention consists of a single tubular conductor, composed of a metal, such as copper, having relatively high heat conductivity and low high frequency losses, this conductor being formed into a series of spaced convolutions, a portion of the turns of which are disposed substantially parallel to one plane while the remaining turns are disposed substantially parallel to a second plane intersecting the first, whereby the two coil portions form in effect a dihedral angle adapted to receive therein the face portion of the object to be hardened, such as an internal combustion engine rocker arm, the portions of the tubular conductor which form the apex of the dihedral angle being preferably spaced with substantial uniformity across the face of the object when so inserted, for purposes of uniformly and efiiciently heating the same. The terminals of the so-wound tubular conductor are connected to suitable electrical conductors for applying a source of high frequency energizing voltage thereto; and also are provided with suitable pipe extensions for circulating a cooling liquid, such as cold water, through the coil during the heating operation.

In the annexed drawing:

Fig. l is a plan view of a coil assembly in accordance with the invention, provided with suitable electrical connections for energizing the coil from a. high frequency source, and provided also with the aforesaid pipe extensions for circulating the cooling liquid through the coil during heating. This View also includes a showing of an internal combustion engine rocker arm as disposed in proper relation to the coil for uniformly heating the face portion thereof.

Fig. 2 is a partial side elevation of the Fig. 1 showing, illustrating particularly the arrange-.

ment of the rocker arm in relation to the coil for the uniform heating aforesaid.

Fig. 3 is a section at 33 of Fig. 2 looking to the right therein; while Fig. 4 is a section at 4-4 of Fig. 2 looking to the left therein.

Fig. 5 is a plan view of the heating coil, corresponding to the showing thereof in Fig. 1, but with the rocker arm removed, to illustrate the coil construction more in detail.

Referring to the various figures of the drawing, in which like elements are similarly designated, the high frequency induction coil of the invention, shown generally at l, comprises, as stated, a single piece of metal tubing 2, Fig. 4, of copper or the like, formed into a series of spaced convolutions, such as 3, 4, 5, 6, a portion, preferably half, of the turns of which, such as 3, 4, are arranged substantially parallel to one plane, while the remaining convolutions, such as 5, 6, are ar anged substantially parallel to a second plane intersecting the first, to form in effect a dihedral angle therebetween, as indicated at I, Fig. 3. This angle is of such aperture as to permit the insertion therein of the portion 8, to be facehardened, of an internal combustion engine rocker arm 9 or the like.

In order to assure substantially uniform heating across the entire face of the portion 8 to be hardened, the portions ID to i3, Fig. 3, of the tubular conductor forming the apex of the dihedral angle 1, are preferably spaced with substantial uniformity in parallel relation and in a common plane, as shown, whereby all portions of the face 8 are subjected to approximately the same flux density, whereby all portions of the face are heated with relative uniformity throughout, so that on subsequent quenching to harden, an even hardness pattern is obtained over the entire rocker arm face.

Since it is desired to impart maximum hardmess to only the face portion 8 of the rocker arm, leaving the balance relatively tough and unhardened, for purposes of withstanding shock, etc., the coil convolutions 3 to 6 inc. are flared progressively outwardly away from the rocker arm face portion as shown at l4, l5, Fig. 1, thereby to minimize heating of the rocker arm, except for the face portion 8.

The coil l is brazed at its terminals [6, IT to the pipe extensions l8, l9, which extend through conductive sleeves 20, 2| of copper or the like, to other pipe extensions, such as 22, 23, the latter extending to a source of supply for circulating cold water or the like through the coil l during operation. The conductive sleeves 20, 2| terminate in right-angle lugs, such as 24, 25, the latter being brazed to conductive connecting lugs 28, 27 secured in position on a high frequency supply transformer '28 by the

transformer bushings

29, 30. An insulating panel 31 through which the copper sleeves 20, 2| extend, is mounted in front of the transformer 28 to protect the operator from the high frequency transformer voltage. During the heating operation, the rocker arm 9 or the like is supported, as shown in Fig. 1, on a cylindrical stud 32 carried by a supporting table 33.

From the aforesaid description of the invention as applied specifically to the face hardening of internal combustion engine rocker arms, its'application to the face hardening of various other objects will be apparent; as will also its application to various other high frequency induction heat treatments, such as annealing, tempering, brazing, soldering, etc.

We claim:

An induction heating coil comprising a length of tubular conductor wound in a plurality of generally helical spaced convolutions of approximately the same dimensions, said convolutions merging into one another in succession continuously from one end of the conductor to the other, a plurality of such convolutions being arranged substantially parallel to a first plane, another plurality thereof being arranged substantially parallel to a second plane intersecting the first and forming thereby a dihedral angle adapted to receive therein a portion of an object to be heat treated, said convolutions all having substantially straight portions disposed in substantially parallel positions along a third plane which is parallel to the line of intersection of said first and second planes, at least four of such parallel portions thus being provided along said third plane for generally conforming to a surface portion of said object to be heated, the remaining portions of the convolutions diverging from said plane at either side along said first and second planes, and a pair of high frequency energizing terminals connected respectively to the ends of saidconductor at the first and last of the successive convolutions.

ROBERT J. STANTON.

CHRISTOPHER LOWRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number -Name. Date 2,052,010 Bailey Aug. 25-, 1936 2,075,079 Anderson Mar. 30,. 1937 2,320,573 Doelker June 1, 1943 OTHER REFERENCES