US2339157A - Method of hardening contiguous areas - Google Patents

Description

/ Jan. 11, 1944. DENNEEN Em 2,339,157

METHOD OF HARDENING CON'IIGUOUS AREAS Filed May 27, 1940 l I INVENTOR Patented Jan. 11, 1944 2,339,157 METHOD or nanpnmc con'rrcuous AREAS Francis S. Denneen, Cleveland, and William C.

Dunn, Shaker Heights, Ohio, Ohio Crankshaft Company, Cleveland,

a corporation of Ohio Application May 27, 1940, Serial No. 337,428

4' Claims. ((11.219-13) The present application is a continuation in part of our application Serial.No. 54,388 filed Dec. 14, 1935, now Patent No. 2,202,759, issued May 28, 1940 and entitled fl-feat treatment of shafts and the like" and is directed mainly to hardening substantially all of the axially -ex-' tending surfaces of a shaft or similar, article in such a way that adjacent areas are hardened to different degrees and/or different depths, the apparatus employed being adapted to hardenall of the surfaces substantially simultaneously and in such manner that the hardened zones blend into each other without a distinctly marked line of change. However, the apparatus employed is capable of beingso adjusted as to leave unhardened areas of any selected widths since in termediate unhardened areas are frequently required. I

In' view of the above conditions, the chief object of the present invention is to provide a method of hardening substantially simultaneously selected parts of a shaft or similar article,

adjacent parts blending together but being of different characteristics. Another object is to provide a method of hardening several areas of a shaft selectively to the same or different degrees of hardness and leaving intervening areas substantially unhardened. A further object is to provide a. method of controlling the rate and amount of quenching as well as the rate and amount of heatingin such adjacent areas. An additional object is to provide a method which is suiiicientlyflexible to permit the use of equipment which is readily applicable to other shafts of approximately the same diameter but having variously arranged hardened zones.

With these and other objects in view, said invention then consists of the method hereinafter described. It will be understood that the following description is not intended to limit the scope of this invention and that the invention may appear in many embodiments differing in detail from this disclosure but within the scope of the appended claims.

The annexed drawing and following descrip tion set forth in detail certain mechanism embodying the invention, such described means, however, constituting but one of the various forms inwhich the principle of our invention may be used.v

In said annexed drawing:

Fig. 1 illustrates the preferred form of our apparatus. Fig. 2 is a section on line 1-4 of Fig. l and diagrammatically includes means of control. v

assignors to The Ohio,

' In the apparatus illustrated in the above fisures, the shaft 12 is inserted in a series of parallel and relatively closely spaced inductors l3, l4, l5, l8 and I1, thesurface of the shaft being spaced from the inner surfaces of the inductors. Heating current. is supplied by the high frequency generator 18 which delivers this current thru the power lines is and 20. Suitable transformers having primaries Zl connected across these power lines and with secondaries 22 connected to the inductors serve as means for converting the relatively high voltage generator output into low voltage current of high'density at the inductors. Condensers such as 23 are connected across the primaries 'so as to tune the circuits for the most suitable heating con- -.ditions. The generator output is controlled by the field resistanc 24. The connections of the secondary coils. to Y the inductors are made at points such as 25 .and '28 which are substantially opposite for proper current distribution, the displaced position'sindicated in Fig. 1 being for ease of illustration. videa transformer for each inductor. However, under some conditions, when the equalization or distribution of current to several inductors is not dimcult, two or more inductors are connected to on secondary such asthe connections illustrated for inductors l4 and;

As it is frequently required to. regulate the heating and/or quenching to control the depth of the hardened zone or its degree of hardness at various parts of the shaft, means is provided to automatically take care of such conditions. Forsuch parts as may require a deep hardened zone, as for instance the spline portion at 21, the heating is begun here somewhat in advance of heating at other parts. This is accomplished by closing switch 28 before closing otherof the pri-. mary. circuits and considerable heating is accomplished in advance after which the remaining circuits are closed.

The heating in various parts of shaft I2 is further controlled by changing the direction of current in one or more of. the inductors relative to the direction of current in the other inductors. Thus if, for instance, the connections for the transformer supplying current to inductor 15 are reversed by means of switch 28a, the current in this inductor atany instant willbe in a direction opposite to that which this current would have if the terminals had not been reversed, i. e., it will be out of its original phase. The flux field produced by this inductor will then oppose that of inductors H. and I! of which the connec- It is customary to protions have not been chanced and in which the current thus remains in its tion.

materially out of phase relative to the current in inductor effected.

The automatic control of such heating and quenching is provided by rotating timer discs having contacts indicated at 3| and 32, the discs being driven by a synchronous motor M,

quenching fluid during and at terval of time he means or method stated by any of the following claims or the equivalent be employed. We, therefore, particularly point tlnctly claim as our, invention:

of such stated means or method out and disof inductors, the inductors being spaced along said article, providing a supply varying current for the inductors, each inductor producing a flux inductor being in timed relation to the current supply to an adjacent inductor article between the inductors, and interrupting the supply of inductors.

2. A method of surface hardening an article, the article being adapted to be hardened by heatcancel the flux field in the space between the inductors to substantially eliminate a, aeneration or heating current in the aforesaid intermediate part of the article, and timing the supply of current to one inductor relative to that being supplied to the other to provide an interval in which substantial heating current is generated in the intermediate part to produce a predetermined heating in said part, the heatin: in said part bein: substantially less than the heating in one of said zones.

FRANCIS s. DENNEEN. WILLIAM c. norm.

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