US2464351A - Method of successively cutting and differentially hardening a toothed member - Google Patents

Description

March 15, 1949 A. E. SHORTER METHOD OF SUCCESSIVELY CUTTING AND DIFFERENTIALLY HARDENING A TOOTHED MEMBER Filed April 19, 1944 4 Sheets-Shet 1 Rm m m0 H 5 E T R E B L A A TTORNEY March 15, 1949. A. E. SHORTER 2,464,351 METHOD OF SUCCESSIVELY CUTTING AND DIFFERENTIALLY HARDENING A TOOTHED MEMBER Filed April 19, 1944 4 Sheets-Sheet 2 IN VEN TOR.

ALBERT E. SHORTER ATTORNEY March 15, 1949. SHORTER 2,464,351

METHOD OF SUCCESSIVELY CUTTING AND DIFFERENTIALLY HARDENING A TOOTHED MEMBER Filed April 19, 1944 4 Sheets-Sheet 3 F/GG INVENTOR. ALBERT E. SHORTER A TTORNEY March 15, 1949.

A. E. SHCRTER METHOD OF SUCCESSIVELY CUTTING AND DIFFERENTIALLY HARDENING A T-OOTHED MEMBER Filed April 19, 1944 F/GZ 4 Sheets-Sheet 4 INVENTOR. ALBERT E. SHORTER ATTORNEY Patented Mar. 15, 1949 M'Errioi OFWSUTCCESSIVELY CUTTING AND DIFFERENTIALLY 'HARDENING A TOUTHED MEMBER Albert Edwar Shorter, Sheflield, England; as-

sigrior to TheLinde Air Products Company, New York, N. Y., a corporation of Ohio Apji'ieatibii April 19, 1944, Serial No. 531.786

In Great Britain May 26, 1943 1 The present invention relates to the production of shaped ferrous metal parts having surface hardened profiles. v I It is common practice to produce shaped ferrous metal articles, suchfa's templates, sprocket wheels, gear wheels and other machine parts and tools Icy cutting the parts from metal blanks using a high temperature severing procedure. It is also l rnown that the profiles of such shaped articles or selected portions thereof may be surface hardened by applying thereto high temperature heat to'raise the surface to the critical point or above and then r'ais ei'y cooling or quenching the heated surface. The employment of two separate heating operations, the first in'the severing procedure, and the seconiclin 'the' har dening process ,;is both time consuming and wasteful of heat energy. H I v According to this invention a shaped ferrous metal part having a surface hardened profile is produced by subjecting a metalbl'ank to a high temperature severing procedure whereby the blank is progressively out to the required profile and progressively quenching the profiled surface before the temperature thereof has fallen below the critical point, whereby a shaped metal part having a surface hardened profile is ohtained.

A preferred method of producing a shaped fermus metal part having a; surface hardened profile in accordance with this invention comprises progressively heating a man blank, directing an oxidising jet upon the heated surface to cut the desired profile and progressively applying a stream of quenching fluid to the profiled surface before the temperature thereof has fallen below the critical point. p I M The quench is preferably applied in the form of an annular stream surroundingthe "cutting point thereby ensuring the quenching of the heated surface despite alterations, in the direction of relative prog'res'sion het'weenlthe metal blank andthe heating and oxidising jet. I v

According to another feature: of'this'. invention apparatus for producing a shaped ferrous metal part having a surface hardened profile, comprises in combination high temperature oxidising means for progressivelyciitting tl' e' metal to the required profile and a quenching device adapted to apply a stream of quenching fiuidt'o the profiled surface before the temperature thereof has fallen below the critical point. M

In accordance with a further feature of this invention amachine for producing a shaped ferrous metal part havi a'gsu-rface hardened profile eoinpi es" in combination a support uni- 4 Claims. (01. 1434)) versally movable in a plane and bearing a tracer mechanism and a cutting burner withassociated' quenching device, the tracer mechanism com prising a mechanically d'riven tracing roller in axial alignment with the cutting burner normal to the plane of movement, and a template" er ranged to guide the tracing roller along a path conforming to the'desired 'profil'e. The machine may be're'ndered substantially wholly automatic by providingin association with the template an electrical control system including limitswitch'es adapted to be actuatedby the tracing roller as it traverse'e the template to turn on and on iht'he desired sequence the supply of the fluids to the cutting burner and quenching device.

The invention will now be described in further detail with reference 'to the accompanying drawings in which:

Fig. 1 is a view in central longitudinal section of a compound cutting burner and quenching device;

Fig. 2 is an underside 'view of the apparatus shown in Fig. 1; 1 Fig. 3 is a View in central longitudinal section of a modified burner and quenching device;

Fig. 4 is 'a fragmentary plan view, somew at diagrammatic, illustrating the path of traverse over the work of the apparatus shown in '2 and 3;

. Fig. 5 is 9; view inside elevation "of a machine for the production'of a surface hardened picnic; a portion being broken away to expose a part of the mechanism; a u

I Fig. 6 is a plan view or the machine shown" in Fig. 5;

Fig. 7 is a plan view of "a detail or the machine shown in Fig. '6, 'on an nlarged scale, an

Fig. 8 is a View in side elevation of another de tail of the machine, on an enlarged scale. I

Referring to Figs. 1-, 2 and 3, a cutting burner B has a substantially cylindrical fn'ozzle pro: vided in known mannerflwithfa central oiifi c e J delivering a jet of oxygen, the central ori'fi a ing: surrounded by an annular row of prehea g orfices Hl'deliveringfa combustible fuel such as an oxyf'ace'tylene mixture. Around the wet dfth nozz'le'N there is mounted a hollow walled cylin drical quenching device Q, the inner wan iii which is a sliding fit with the wall of are nb'zzie N. The quenching device Q has an inlet in t P fitted with a conduit C for connection to asiipply o f 'qu"ejn'ching fluid which, in most instances; will be cold water and 'a series of discharge orifices 10 for producing a'ring of quenching jets arranged to impinge upon the heated surface along the circumference of a circle centred on the cutting point. Since the inner wall of the quenching device Q is in close contact with the nozzle N, the quenching liquid delivered to the quenching device serves also as coolant for the nozzle.

To prevent the quenching fluid discharged from orifices from interfering with the heating and cutting jets, a shield S is provided between these jets and the quenching jets. The shield S may be constituted as an extension of the inner wall of the quenching device Q, the exension projecting forwardly of the nozzle N to terminate close to the surface of the work W being cut when the nozzle N is positioned at the correct distance from the surface. Gas escape slots G may be formed in the end surface of the shield S to permit the products of combustion to escape readily.

As the distance of the nozzle N from the surface will need to be varied with different thicknesses and composition of metal or alloy being cut, it is of advantage to arrange for the shield S to be adjustable with respect to the nozzle N, so that the shield may be maintained close to the work for all settings of the nozzle N. Withthe arrangement shown in Fig. 1, this is achieved by simply sliding the quenching device Q, of which the shield S forms an integral part up or down the nozzle N. In the modification shown in Fig. 3, which in all other respects is substantially identical with that shown in Figs. 1 and 2, the quenching device Q and shield S integral therewith threadedly engage the nozzle N. The requisite adjustment of the nozzle N with respect to the surface to be cut is effected by screwing the quenching device Q about the nozzle N. A looking nut L may be provided for securing the quenching device in the desired position.

The operation of cutting and hardening a profile using the apparatus shown in Figs. 1, 2 and 3 will be clear by reference to Fig. 4, where J represents the cutting jet, H the line of impingement of the preheating jets, and Q the line of impingement of the quenching jets upon the surface of the work W. At the starting point, the preheating jets are lighted up and, after heating for the appropriate period as determined by the thickness of the material being cut, the oxidising jet is turned on. At the same instant the quenching jets are turned on and the apparatus is traversed over the material either by hand or by a machine, the line of traverse being either marked upon the surface beforehand or a template provided for guiding the cutting jet along the required path. The cutting operation raises the temperature of the metal along the line of cut above the critical point and the temperature will not have fallen below this point when, in the course of traverse, the cut profile comes under the influence of the quenching jets which rapidly cool the heated surface below the critical point and thereby produce a hardened surface. In Fig. 4 there is illustrated the cutting and hardening of a toothed profile T, where the direction of traverse is constantly changing. In advancing along the tooth flank T already cut, the burner moved leftwardly but after passing the apex to cut the tooth flank T the burner moves rightwardly. By surrounding the cutting jet with an annular quenching jet, the quenching of the heated cut profile is ensured whatever the direction of traverse may be at any instant.

A machine for producing a shaped ferrous metal part having a surface-hardened profile in accordance with the invention is shown in Figs. 5 to 8 to which reference will now be made.

.4 For purpose of illustration the set up and operation of the machine will be described in connection with the cutting from an annular blank with sequent hardening of a component having a number of identical profiles uniformly spaced around the periphery. An example of such a component is a sprocket wheel.

The machine comprises a massive four-sided base Ill having a transverse partition H on which is mounted a support l2 for the work W. Where,

as in the present example, a number of profiles are to be produced arranged around the circumference of a circle, the work support l2 comprises a turntable; where the profiles are disposed linearly, a machine slide would replace the turntable. The partition II has a drain l3 leading to an outlet M for the quenching liquid. To one side of the base l0 there is secured a pedestal l5 supporting a vertical column [B which carries an upper arm 11 and a lower arm l8 extending over the work sup-port l2. The two arms ll, l8, are slidably mounted on the column I6 and are arranged to be clamped firmly thereto by means of clamps I9, 20, respectively.

At its end remote from column Hi, the upper arm I! carries a template 2| of form-magnetic material for propelling the cutting burner B and quenching device Q along the desired path. With the template 2| there is associated an electrical control system comprising four limit switches to be described in detail later, the switches being connected to a control cabinet 22 by current leads extending through a sheath 23. l

The lower arm I8 is articulated so as to be uni-- versally movable in a plane and is known in the cutting machine art as a folding gate arm. The arm l8 constitutes a support for a tracer mechanism M and a cutting burner B with associated quenching device Q. The tracer mechanism M comprises a mechanically driven mag netic tracing roller 24 arranged to bear against the template 2 l, the roller 24 being in axial alignment with the burner B normal to the plane of movement. The roller 24 is adapted to be energised by a magnet coil which causes the roller 24 to adhere to the edge of the template and is caused to travel around the template by means of a driving motor 25, which may be a variable speed electric motor, to which the roller 24 is coupled through a gear box. The construction and operation of such tracer mechanism is well known in the art and no detailed description thereof is deemed necessary. The burner B, which is se-- cured to the arm l8 by a clamp 26, is furnished with a nozzle N on which the quenching device Q is mounted as described above with reference to Figs. 1 and 2 or Fig. 3.

The cutting oxygen is supplied to the burner B through a solenoid-operated valve 21 and flexible conduit 28, the gaseous fuel for preheating is supplied through a solenoid-operated valve 29 and flexible conduit 30; the quenching liquid is supplied to the quenching device Q through a solenoid-operated valve 3! and flexible conduit 32. A pilot light 33 supplied with a gaseous fuel through a flexible conduit 34 may be provided to ignite the preheating jets.

In the particular example taken to illustrate this invention, namely the production of a sprocket wheel, the guiding surface or edge 35 to which the roller 24 adheres is an internal boundary formed by an opening in the template 2| as will be clear from Fig. '7. The guiding edge 35 is mounted in vertical alignmentwith the work W and having been properly orientated radially and circum'ferentially with respect thereto, the burnere with the quenchingdevice Q operates simultaneously through the same pathas the roller 24 to produce a surface hardened profile in the manneidescribed above with reference to Figs. 1 to i. In sprocket wheels and other toothed members, which in use are subject to wear and impact mainly along the flanks and root of each tooth, it is usually desirable for the apex to have a less hard but tougher structurethan the flanks and root. The ensuing description shows howsuch differentially hardened teeth may beautomatically produced insuccession around the periphery of the Wo k W- The sequence of operations involved in the production of such a toothed member, starting at the apex of one tooth, moving along a flank and root and finally along the flank of an adjacent tooth to the apex thereof, isas follows:

a. The turning on of the preheating jets and subsequently of the oxidising jet with sequent starting of the burner along the desired path;

b. The turning on of the quenching jets as soon as the oxidising jet has moved a predetermined distance alonga tooth flank from the apex;

c. Theturning oil of the quenching jets as the burner approaches the apex of the second tooth;

d. The turning off of the preheating and oxidising jets when the apex of the second tooth is reached.

On completion of this sequence of operations, the burner is returned to the starting position whilst the work is moved through one tooth space so that the apex of the second tooth becomes the starting point of the second sequence of operations. This is repeated round the whole circumference of'the blank until the burner once again reaches the apex of the first tooth. I

Reverting to Fig. '7, the aforementioned operations a, b, c, d are initiate'd'in turn at the four similarlyde'ttered points shown on the guiding edge of the template 2| by an'electrical control system now to be described.

At each of the four points a, b, c, d there is a limit switch LSA, LSB, LSC, LSD respectively, the four switches being secured to template 2| and connected to relays (not shown) housed in control cabinet 22, which cause the solenoid perated valves 21, 29, 3|, to be turned on and off in the desired sequence. A main switch MS, which may be of the push button type, controls the starting of motor 25 and the energisation of the magnet coil associated with the tracing roller 24. Switch MS is mounted on a switch panel SP secured to the front of the base l0 (Figs. 5 and 6). A second push button switch OS is mounted on panel SP for breaking the circuit, together with three further switches QV, FV, and 0V. Switch QV is arranged to complete the circuit through the solenoid of quench valve 3| independently of the control exercised by the limit switches on the template to permit of testing the supply of quenching medium; switches FV and 0V perform analogous functions in the circuits through the solenoids of fuel gas valve 29 and oxygen valve 21 respectively.

Except that switch LSA is associated with a latch mechanism LM, the four limit switches are identical, being simple make-and-break contact switches which are closed in turn by the tracing roller 24 as it traverses the guiding edges 35. The latch mechanism LM serves the function of preventing the roller 24 from traversing the guidi l'as f 5. f r eciecr ti d in e va I n rt s h tt s rqi is ter hat may b 'imfi-l parted to the work before the cutting x en is turned on. As will be clear by reference to Fig. 8, the lat-ch mechanism LMcomprises a roller 36 carried by a stem 3'! slidably mounted in a guide 38 constituting an extension to ,the switch lever 39 of limit switch LSA. Stem3'l is secured to a flexible cable 49 by means of which itcan be retracted to lift the roller '36 out of the path of the tracing roller 24. A helical spring 4| is provided to restore the roller 36 to its original position when the cable 40 is'released'. h N v The sequenceof operation is as follows; Y I Prior to starting, the tracing roller 2415 moved mum; he gu ed efi tin-i sinthe. i in ty bf. h po t O l s r o t e. mai swi ch motor 2. t rt ter t the raci gro l'er- 24 whilst simultaneously the magnet cell which magnetises roller 24 is energised. The roller 24 moves slightlyaround the guiding edge 35 in a clockwise direction to abut, against the latch roller 35 causing switch 39 to close, further traverse of the tracing roller 24 aro'und the guide ing edge 35 being prevented by the latch roller 36 although the tracing roller 24 continues to rotate. Closure of switch 39 energises the solehold-operated fuel gas valve 29 to turn on the preheating gas to burner 13 which isignited at thenoZiZle N by the pilot light 33. After apreheating period, solenoid-operated valve 21 is energised to turn on the supply of cutting oxygen to the nozzle N which moves round the guiding edge 35 in a clockwise direction and thenormal cutting operation proceeds along the tooth flank until the tracing roller 24 reaches thepoint b' where it abuts against the leverof limit switch LSB to close this switch, thereby causing the energisation of the solenoid-operated quench valve 3| to turn on the supply of quenching medium to the quenching device Q. Tracing roller 24 con: tinues to roll round the edge 35 untilit reaches the point 0 where it closes limit switch LSC to turn off the supply of quenching medium as the cutting operation approaches the apex of the second tooth. Further movement of the tracing roller 24 brings it to the position d where it closes limit switch LSD to shut off both the preheating gas and the cutting oxygen supply. Tracing roller 24 continues to move round the edge 35 to return to the starting point whilst the work W is rotated to bring the apex of the second tooth immediately below the point a, whereupon switch MS is again closed and the cycle of operations is repeated.

I claim:

1. Method of successively cutting and diirerentially hardening a toothed member to cause the apex of each tooth to have a less hard but tougher structure than the flanks and root, which comprises directing a preheating jet and subsequently a cutting stream of oxygen against a blank at the apex of a tooth, relatively propelling said jet and cutting stream with respect to a blank to form a kerf along the flank and root of said tooth and the adjacent flank of the next tooth, directing a quenching jet against the kerf as soon as the oxidizing stream has moved relatively to the blank a predetermined distance along the flank of the first tooth and causing said quenching jet to follow said cutting stream, turning ofi the quenching jet as the cutting stream approaches the apex of the second tooth, and completing the cut to the apex of the second tooth.

2. Method of successively cutting and difierentially hardening a toothed member to cause the apex of each tooth to have a less hard but tougher structure than the flanks and root, which comprises directing a preheating jet and subsequently a cutting stream of oxygen against a blank at the apex of a tooth, relatively propelling the blank and said jet and cutting stream along the flank and root of said tooth and the adjacent flank of the next tooth, directing quenching fluid against said blank in an annular stream concentric with the cutting stream as soon as the cutting stream has moved relatively to said blank a predetermined distance along the flank of the first tooth,

causing said quenching stream to move with said cutting stream relatively to the blank While maintaining such concentric relation and thereby insuring quenching of the heated kerf despite change in direction of relativemovement of the cutting stream, and turning off said quenching stream as the cutting stream approaches the apex of the second tooth.

3. Apparatus for successively cutting and differentially hardening a toothed member to cause the apex of each tooth to have a less hard but tougher structure than the flanks and root, which comprises a burner nozzle for directing a preheating jet and subsequently a cutting stream of oxygen against a blank at the apex of a tooth, a support for said burner nozzle universally movable in a plane and bearing a tracer mechanism for propelling said burner along the flank and root of said tooth and the adjacent flank of the next tooth, a quenching device surrounding said burner nozale and constructed and arranged to project an annular stream surrounding said preheating jet and cutting oxygen stream, a limit switch actuated by said tracer mechanism for turning on said quenching device as soon as the cutting oxygen stream has left the apex and has moved a predetermined distance along the flank of the first tooth, and another limit switch actuated by said tracer mechanism for turning 01f said quenching device as the cutting stream approaches the apex of the second tooth.

4. Method of successively cutting and differentially hardening a toothed member to cause the apex of a tooth to have a less hard and tougher structure than the flanks, which comprises directing' a cutting oxygen stream against a blank at the apex of a tooth, relatively propelling the blank and said cutting stream to form a kerf along the flank, directing a quenching jet against the kerf as soon as the cutting stream has moved relatively to the blank a predetermined distance along the flank and causing said quenching jet to follow said cutting stream, turning off the quenching jet before the cutting stream reaches the apex of the second tooth, and completing the cut to the apex of the second tooth.

ALBERT EDWARD SHORTER.

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

UNITED STATES PATENTS Number Name Date 1,145,875 Andres July 13, 1915 1,396,993 Carter Nov. 15, 1921 1,585,893 Coberly May 25, 1926 1,799,614 Coberly Apr. 7, 1931 1,869,836 Anderson Aug. 2, 1932 1,969,840 Goddard Aug. 14, 1934 2,051,915 Sykes Aug. 25, 1936 2,065,627 Taylor Dec. 29, 1936 2,170,876 Shorter Aug. 29, 1939 2,187,731 Davis Jan. 23, 1940 2,190,360 Howard Feb. 13, 1940 2,208,121 Davis July 16, 1940 2,227,476 Williams et a1 Jan. '7, 1941 2,274,005 Shorter Feb. 24, 1942 2,286,591 Van Triest June'16, 1942 2,296,612 Gridley Sept. 22, 1942 FOREIGN PATENTS Number Country Date 632,258 Germany July 4, 1936 527,725 Great Britain Oct. 15, 1940

Images