US2794894A - Induction heat-treating apparatus - Google Patents

Description

u 1957 c. A. TUDBURY 2,794,894 mnucnou HEAT-TREATING APPARATUS Filed Oct. 5, 1954 a SheetsSh et 1 INVENTOR. CHESTER A. TUDBURY A TTORNEY June 4, 1957 c TUDBURY 2,794,894

INDUCTION HEAT-TREATING APPARATUS Filed Oct. 5, 1954 s sheets-$11281; 2

AIIORNEY June 1957 c. A. TUDBURY 2,794,894

INDUCTION HEAT-TREATING APPARATUS Filed Oct. 5, 1954 3 She,ets-Sheet 5 m 49 o I N Y ;;L@ Q o I j I24 0 g g L 70 INVENTOR. CHESTER A. TUDBURY A TLORNE Y United. States Patent ()fiice 2,794,894 Patented June 4, 1957 2,794,894 INDUCTION HEAT-TREATING APPARATUS Chester A. Tudbury, Cleveland, Ohio Application October 5, 1954, Serial No. 460,462

7 Claims. (Cl. 219--l0.57)

This invention pertains to the art of high-frequency induction heating and, more particularly, to apparatus for automatically heat treating a series of elongated workpieces each having a plurality of spaced areas to be hardened.

The invention particularly pertains to the heat treating of camshafts as used in internal combustion engines and will be described with particular referencethereto, although it will be appreciatedfrom a reading of this specification that the invention has .broader applications. As is known, camshafts are used in internalcombustion engines for the purpose of opening and closing valves, allowing the entrance and exit of air fuel mixtures and burned gases. A camshaft will normally have two cams for each cylinder of the engine, plus intermediate bearing areas. Thus, a camshaft for a conventional automotivetype engine may have sixteen cam surfaces, plus eight intermediate bearing surfaces which must be heat treated. In the past, such cam and bearing surfaces were heat treated, one or two at a time. This required an inordinately large amount of time and required excessive handling of the camshafts. In any event, the operation was relatively expensive.

The present invention contemplates apparatus which enables all of the areas on the camshaft to be hardened simultaneously and for such camshafts to be automatically loaded and unloaded.

In accordance with the present invention, apparatus is provided including a base, a plurality of inductors mounted on the base in side-by-side spaced relationship with the workpiece opening of the inductors all in axial alignment. A rack slidable on the base on a line of movement parallel to the axes of the openings has spaced workpiecesupporting means thereon. One Of such means includes an elongated member having a line of movement through the workpiece openings and a length at least greater than the maximum spacing between the inductors. Power means are provided for selectively causing the supporting means to release or engage a workpiece.

A magazine is provided on the base at the end of the inductors opposite from that of the elongated member. A transfer mechanism is provided for moving workpieces from the hopper to a position where they may be engaged by the workpiece-supporting means, which transfer mechanism is so arranged as to receive a workpiece from the hopper at the same time as it receives a completed workpiece from the rack for disposal. Such transfer mechanism then operates to move a workpiece from the hopper to the rack and, at the same time, disposes of the completed workpiece.

The principal object of the invention is the provision of new and improved apparatus for automatically hardening a plurality of areas simultaneously on an elongated workpiece and for automatically loading and unloading such workpieces.

Another object of the invention is the provision of a new and improved mechanism for automatically hardening all of the bearing areas on a camshaft simultaneously.

Still another object of the invention is the provision of new and improved apparatus for inductively heat treating elongated workpieces comprising a plurality of highfrequency inductors with their workpiece openings in spaced aligned relationship, a rack having workpiece supporting means movable on a line of movement parallel to the openings through the inductors, one of the means being elongated and having a line of movement through the openings whereby a workpiece may be positioned in the rack automatically and then advanced in a single movement into the high-frequency inductors.

The invention may be comprised in certain parts and arrangement of parts, a preferred embodiment of which will be described in this specification in detail and illustrated in the accompanying drawing which is a part hereof, and wherein:

Figure l is a partial top elevational view of apparatus embodying the present invention;

Figure 2 is a front elevational view of Figure l;

. Figure 3 is'an end elevational view of Figure 2;

Figure 4 is a cross-sectional view of Figure 1 taken approximately on the line 44 thereof; and

Figure 5 is'a cross-sectional view of Figure 1 taken approximately on the line 55 thereof.

Referring now to the drawings wherein the showings are for the purposes of illustrating a preferred embodiment of the invention only and not for the purposes of limiting the invention, the figures show high-frequency heat-treating apparatus including a workpiece A in the position of being supported on a rack B after just having been transferred from a hopper C by a transfer mechanism D and just prior to being advanced into a plurality of high-frequency inductors E for the purpose of being heat treated. All of the above is supported generally on a base F of a size sufiicicnt to hold the above mechanism and other associated apparatus.

The workpiece A is in the form of a camshaft for internal combustion engines and, as such, is in the form of an elongated shaft 5 having a plurality of cylindrical bearings 6, 7 and 8 in spaced relationship along its length. These bearings, as is known, are mounted in suitable hearing supports in the internal combustion engine block and support the camshaft for rotation about an axis. intermediate the bearings 6 and 7 are a pair of cams 1 and 2 and intermediate the'bearings 7 and 8 are a pair of cams 3 and 4. These cams actuate valve in the internal combustion engine. The bearing surfaces and the cam surfaces must be hardened. The present invention contemplates hardening these surfaces in a single operation.

The camshaft 5 also has a flange end 9 by which the camshaft may be positively driven when placed in the engine. The ends of the camshaft are provided with conical openings coaxial with the axis of rotation of the bearings 6, 7 and 8.

The base F forms no part of the present invention. It is generally a frame and sheet steel construction and is generally rectangular at top plan view. It has an upstanding portion 10 on the back edge of the base in which impedance-matching transformers and other apparatus associated with high-frequency induction-heating equipment may be housed. This portion 10 has a front surface 11 on which the inductors E are mounted. The number of inductors E employed will correspond to the number of surfaces on the camshaft to be hardened. In the embodiment of the invention shown, seven inductors are illustrated. Obviously, more or less can be employed depending on the number of areas to be hardened with a spacing corresponding to the spacing of the areas on the workpiece to be heat treated. As shown, these inductors are in spaced aligned relationship. Each have a workpiece-receiving opening 12 of a radius at least greater than the maximum radius of the camshaft A at any point. Thus, when the camshaft A is positioned within the workpiece opening 12, the camshaft may be rotated without at any time striking the surfaces of the inductor E. Also, the camshaft may be advanced axially through the aligned openings.

The inductors E are relatively conventional and include generally a C-shaped loop having a pair of fishtail leads 16 extending from the split thereof in closespaced parallel relationship to terminal blocks 18. These terminal blocks are connected to corresponding terminal blocks 19 on impedance-matching transformers and by this construction, the inductors E are supported in the positions shown. Obviously, the inductors E may be hollow and cooling water may be circulated therethrough as is conventional in the induction-heating art to remove any heat generated within the inductor during the heating operation. They are also fitted with an integral quench arrangement as described and claimed in U. S. Patent No. 2,170,130 owned by the assignce of this application.

As is known, camshafts positioned within the workpiece-receiving opening 12 will be rapidly heated directly opposite each inductor by high-frequency currents flowing in the inductor itself and then hardened by the quench medium projected thereonto.

Shielding rings 75 comprised of a solid copper loop (see Figure 5) with openings aligned with the. openings 12 of the inductors are positioned between each inductor E. Such rings 75 prevent heating of the workpiece in between the adjacent inductors E. The axial length and extent of nonheat treated area may be readily controlled by adjusting the dimension of the ring 75.

The workpiece A is carried into and out of the workpiece opening 12 of the inductors E by means of the rack B which is movable on a line of movement parallel to a line through all of the workpiece-receiving openings 12. The rack B comprises generally a left-end member 20 and a right-end member 21 rigidly interconnected by means of a rod or shaft 22. This rack B is supported for sliding movement on the base F by means of ways which, in the embodiment shown, comprise a pair of cylindrical bars 24 on which the left-end member 20 slides and a pair of cylindrical bars 25 on which the right-end member 21 slides. These bars 24, 25 are fixed at their ends in blocks 26, 27 respectively rigidly mounted on the base F. It will be noted that the length of the ways is greater than the maximum spacing between the right and left hand inductors. Thus, the rack B can have a length of movement greater than the maximum spacing of the high-frequency inductors E.

The right-end member 21 has an elongated workpiecesupporting member 30 rotatably supported thereon and extending to the left on a line corresponding to the axis through the workpiece openings 12. This member 30 is rotatably supported in bearings 31, 32 at its right-hand end. The left-hand end of the member 30 is provided with means for releasably engaging the right-hand end of the camshaft A and, in the embodiment shown, a lathe center 34 is provided. It will be noted that a slide bearing 36 is provided on the base F which provides a rotatable sliding support for the member 30 when the rack is in its right-hand position.

The member 30 is also slidable along its axis for short distances in the bearing 31, 32. It is urged toward the left by means of a helical coil spring 38. A collar 39 provides a stop limiting the left-hand movement. When a camshaft A is loaded in the rack as will subsequently appear, the member 30 slides to the right and the collar 39 engages a limit switch 40. This limit switch is for the purpose of preventing energization of the inductors E unless a camshaft A is supported on the rack B. Other limit switches can be provided to insure that the rack is in the right-hand position before these inductors E are electrically energized.

The left-hand end member 20 has a shaft 42 rotatably iii and slidably supported thereon on a line through the axis of the shaft 30. This shaft 42 likewise has means for supportingly engaging the workpiece A and, in the embodiment shown here, is a lathe center 43. A lever 44 pivoted on the member 20 about a vertical axis 45 engages the left-hand end of the shaft 42 and slides the shaft 42 in its bearing 47. Power means in the form of a hydraulic cylinder 48 mounted on the base F and having a push rod 49 actuates a lever 44 when the rack is in the left-hand position for the purpose of releasing a camshaft from the rack when the shaft 42 is in its left-hand position and for re-engaging a camshaft when the shaft 42 is moved to its right-hand position.

An electric motor 50 is also mounted on the left-end member 20 and through suitable mechanism not shown rotates the shaft 42. Such rotation of the shaft 42 is transmitted to the workpiece A through the lathe center 43 and during the heating operation the workpiece A is preferably continuously rotated. As above pointed out, the shaft 30 is also rotatable and also rotates during a heating operation because of the driving connection between the lathe centers 43 and 34 through the workpiece A.

Workpieces A to be processed by the apparatus are first placed in the hopper C. In the embodiment shown,

- the hopper comprises two spaced angle sections 51, 51a

mounted on the back of the base F and sloping toward the front. Camshafts are placed in the hopper and roll toward the front of the base F under the force of gravity. A dog 53 mounted on the front edge of the hopper prevents the' workpieces from falling off of the hopper C except when needed.

The transfer mechanism D advances camshafts on the hopper C to the rack B. In the embodiment of the invention shown, the transfer mechanism D comprises a plate 55 supported for vertically sliding movement on the base F. A pair of V blocks 56 mounted on the upper edge of this plate and extending to the front therefrom receive camshafts from the hopper C. The plate 55 also has a second pair of V blocks 57 located below the upper V blocks 56 which are intended to receive workpieces from the rack B and dispose of them. The plate 55 is moved vertically by means of a hydraulic cylinder arrangement 60 having a vertically extending connecting rod 61 connected to the lower edge of the plate 55.

In a like manner, a hydraulic cylinder 64 is provided mounted on the base F and having a connecting rod 65 connected to the right-hand end member 21 of the rack B for the purpose of sliding the rack B from a right to a left-hand position and return. Obviously, in the left-hand position, the rack is in the load position and in the righthand position is in the heat-treat position.

In order to describe the operation of a preferred embodiment of the invention, it will be assumed that the rack is in the left-hand position and that camshafts to be hardened are in the hopper C. The transfer mecha nism is first moved upwardly by means of its hydraulic cylinder 60. When the mechanism reaches the upper end of its stroke, it engages the dog 53, releasing a camshaft which then rolls into the upper V blocks 56. The transfer mechanism then reverses itself and drops the V blocks 56 until the center of the camshaft is aligned with the centers of the lathe centers 34, 43. At this time, the hydraulic cylinder 48 which has previously been in the position to have retracted the shaft 42 is actuated to advance the shaft 42 to the right so that the center 43 engages the left-hand end of the camshaft A. The camshaft A is then pushed onto the center 34 and the shaft 30 is pushed to the right until the collar engages the lefthand end of the member 21. At this time, the collar 39 actuates the limit switch 40, indicating that a camshaft is satisfactorily loaded on the rack B. The transfer mechanism then lowers itself to remove the V block 56 from the alignment of the camshaft A. Thereafter, the rack B is moved to the right by means of the hydraulic cylinder 64. At the same time, the motor 50 is energized to rotate the workpiece A. When the rack B has moved to the full right-hand position, the high-frequency inductors are ready to be energized. Normally, these inductors rapidly heat the camshaft while it is rotating in the bores and, thereafter, quench water is sprayed through tge inductors to quench the heated surfaces of the cams aft. 1

When the heating operation is finished, the hydraulic cylinder 64 is actuated to advance the rack to the lefthand position. In the meantime, however, the transfer mechanism has been actuated to bring the V blocks 56 above the line of the camshaft but allowing the V blocks 57 to be below the line of the camshaft. Thereafter, the transfer mechanism moves further upwardly until the dog 53 is engaged and a new camshaft advances into the upper V blocks 56. At the same time, the hydraulic cylinder 48 is actuated to retract the shaft 42 and the process workpiece drops into the lower V blocks 57. The transfer mechanism D then lowers, bringing a new camshaft into alignment with the centers 43, 34 and the camshaft in the block 57 engages the rack 70 and is removed from the V blocks 57. The camshaft then rolls forwardly and out of the machine, inasmuch as the rack 70 slopes forwardly and downwardly.

By virtue of. the present invention, it has been found possible to easily heat treat as many as 700 camshafts per hour per machine, a speed heretofore unheard of in the heat-treating industry. This is approximately 14,800 camshafts per day.

Obviously, the apparatus described can be readily adjusted to harden any length of camshaft within its limitations. Thus, it is entirely possible by providing different degrees of projection of the centers 34 or 43 or by providing different length members 30 to readily handle any length of camshaft. ferent inductors E with different sized workpiece openings, many diameter cams can be readily handled.

As pointed out above, it is preferred that the inductors B have an integral quench arrangement whereby the heated surfaces on the camshaft may be quenched in position. If desired, and with certain type of metals, it is possible that the quenching may be delayed for a time period to enable the camshaft to be returned to the load position and then dropped into a quench tank aligned with the hopper and below the rack 70.

The invention has been described with particular reference to a preferred embodiment. It will be obvious that modifications and alterations will occur to others upon a reading and understanding of this specification and it is my intention to include all such modifications insofar as they come within the scope of the appended claims.

Having thus described my invention, I claim:

1. High-frequency induction heat-treating apparatus of the type described comprising, in combination, a base, a plurality of closed high-frequency inductors mounted on said base and having aligned openings with a common axis, a rack movable on said base on a line of movement parallel to said axis, said rack being elongated in said line of movement, an elongated member on one end of said rack extending toward the opposite end thereof and aligned with said axis, means on the end of said member for supportingly engaging a workpiece and means on the other end of said rack aligned with said axis for supportingly engaging a workpiece in cooperation with the means on said member, said rack being movable from a first position where said member is in said aligned openings and a workpiece may be readily positioned in said means or removed to a second position where said workpiece is within said openings.

2. High-frequency induction heat-treating apparatus of the type described comprising, in combination, a base, a plurality of high-frequency inductors mounted on said base with aligned workpiece-receiving openings having a common axis, a rack mounted on said base for movement Furthermore, by providing dif- 1 with a line of movement parallel to said axis and being elongated in said line of mpvement, a member elongated in said line of movement mounted on one end of said rack and extending toward the opposite end and being aligned with said axis, a slide member on said base at the end of said inductors corresponding to said one end of said rack for slidably supporting said member, means on the end of said member for releasably engaging a workpiece, means-on the other end of said rack for releasably engaging a workpiece and means for moving said rack on said line of movement.

3. In high-frequency induction heat-treating apparatus of the type described comprising, in combination, a base, a plurality of high-frequency inductors each having a workpiece-receiving opening all with a common axis, a rack movable on said base on a line of movement parallel to said axis and being elongated in said line of movement, an elongated member mounted on one end of said rack extending toward the opposite end and being aligned with said axis, means on the end of said member for releasably engaging a workpiece, a second member mounted on the opposite end of said rack aligned with said first member and said axis, said second member having means for releasably engaging a workpiece and means for rotating said second member whereby a workpiece may be continuously rotated when in the inductors and means for reciprocating said rack, said rack being movable from a position where said elongated member is in said inductor openings and a workpiece can be positioned between said members to a position where said elongated member is withdrawn from said openings and the workpiece is within said openings.

4-. High-frequency induction heat-treating apparatus of the type described comprising, in combination, a base, a plurality of high-frequency inductors mounted on said base with aligned workpiece openings having a common axis, a rack removable on said base with a line of movement parallel to said axis and being elongated in said line of movement, an elongated member on one end of said rack extending toward the opposite end and aligned with said axis, means on the end of said member for releasably engaging a workpiece, a second member on the opposite end of said rack aligned with said first mentioned member, said second member being reciprocable and power means for reciprocating said second member toward and away from said first member whereby to engage or release a workpiece respectively and means for reciprocating said rack.

5. High-frequency induction heattreating apparatus comprising, in combination, a plurality of high-frequency inductors each having a workpiece-receiving opening all on a common axis, a solid shield ring positioned between at least pairs of said inductors and having workpiecercceiving openings aligned with the workpiece-receiving openings of said inductors, a rack movable on said base and having a line of movement parallel to said axis, an elongated member on one end of said rack extending toward the opposite end and aligned with said axis, means for reciprocating said rack on said base to move said member into and out of said workpiece-receiving openings, a second member on the opposite end of said rack, both of said members being reciprocable and rotatably mounted relative to said rack, power means for rotating at least one of said members, power means for recipro eating one of said members whereby a workpiece may be releasably engaged, the other of said members being on said base with a line of movement parallel to said axis, workpiece-supporting means on said rack aligned with said axis, one of said means being elongated and movable through said workpiece openings to receive a workpiece and out of said openings to bring a workpiece into said inductor openings and support it there for heat treatment, means for actuating said means to releasably engage a workpiece and power means for reciprocating said rack.

7. High-frequency induction-heating apparatus of the type described comprising, -in combination, a base, a plurality of high-frequency inductors mounted on said base and having workpiece-receiving openings with a common axis, a rack reciprocably supported on said base with a line of movement parallel to said axis, spaced workpiecesupporting means on said rack aligned with said axis, one of said means being elongated and movable through said workpiece openings to receive a workpiece and out of said openings to support a workpiece in said inductor openings, means for actuating said means to releasably engage a workpiece and power means for reciprocating said rack, transfer mechanism movable in a vertical direction on said base and having upper and lower workpiece supports, said upper supports receiving a workpiece from a hopper when the mechanism is in the upper position while said lower supports receive a workpiece from said rack, said mechanism being movable to a lower position whereby to provide a workpiece to said rack while the workpiece in the lower supports is being removed from said lower supports for removal from the apparatus.

References Cited in the file of this patent UNlTED STATES PATENTS 2,255,103 Denneen et a1. Sept. 9, 1941 2,452,801 Storm Nov. 2, 1948 2,574,564 Hogel et a1 Nov. 13, 1951 2,604,577 Strickland et a1. July 22, 1952

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