US2282942A - Flame hardening - Google Patents

Description

May-12, 1942. J. J., CROWE FLAME HARDENING Filed April 2, 1940 2 Sheets- Sheet 1 -depth below the surface.

Patented May 12, 1942 John J. Crowe,

Reduction Company, Incorporated, N. Y., a corporation of New York Westfield, N. 1., assignor to an- New York,

ApplicationApril z, 1940, Serial'No. 327,401

14 Claims. '(01. 148-21) This invention relates to flame hardening. and more particularly to methods and apparatus by which a work-piece can be hardened to a uniform depth in spite-of variations in the section of metal.

In flame hardening operations, the heat of high-intensity flames, such as oxyacetylene flames, is applied to the surface of the workpiece and the metal is heated above its critical temperature on the surface and for a limited The depth to which the metal is heated above its critical temperature depends upon a number of factors including the intensity of the heating jets, thenumber of jets, the length of time'that the heat is applied, and the mass of underlying metal into which heat flows by conduction.

It is an object of this-invention to prevent variation in the depth of hardness as a result of differences in the mass of underlying metal at different parts of a workpiece, and this result is obtained by producing compensating variations in one or more of the other factors that effect the depth of hardening,

In the preferred embodiment of this invention 4 different numbers of flame jets are used to compensate for differences in the mass of metal into which heat is lost by conduction. In this way thedepth of metal that remains heated above its critical temperature can be kept substantially constant throughout the length of a section. The

invention changes the number of flames in actaken from such an angle that the bottom face of the-torch block is visible. Y

Figs. -9 are diagrammatic elevations, on a reduced scale, showing the variation in the number of flamesoperating while the torch block of Fig, 2 is moved progressively along the workpiece. Fig. 1 shows a torch block H in which are two separate distributing chambers, a longitudinal chamber l2 and a transverse chamber I3. A

. mixture of oxygen and fuel gas, preferably an oxyacetylene mixture, is supplied to the longithe upstream side.

cordance with their longitudinal displacement during a progressive flame hardening operation.

The same result can be obtained by changes in.

the intensity of the flames, but variation in the number of flames can be obtained more advantageously in practice.

Other objects, features and advantages of the invention will appear or be pointed out as the specification proceeds.

In the accompanying drawings, forming part hereof:

Fig. 1 is a perspective view, partly diagram matic, illustrating the manner in which a round body is hardened in accordance with this invention.

Fig. 2 is a perspective view showing apparatus for hardening a flat. work-piece in accordance with this invention.

Fig. 3 is an enlarged vertical section through the torch block on the line 3-3 of Fig. 2.

Fig. 4 is an enlarged perspective view of one end of the torch shown in Fig.

tudinal distributing chamber i2 bytubing IS. A similar gas mixture is supplied to the transverse distributing" chamber l3 by tubing 16 that communicates with the chamber I3 through a passage in the torch block ll. p

A row of 'evenlyspaced flame jet orifices l8 open.throug-h the' top face of the torch block H and at their lower ends'open'into the distributing chamber l2. A s'imilar'transverse row of flame jet orifices [9 leading from the chamber 13 open through the top face of the torch block.

The supply of .gas to the tubing l5 and I6 is controlled by quick-acting shut-off valves 2| and 22; respectively. Fuel gas is supplied through a tube 23 and oxygen'through a tube 24 to an inlet pipe 26 that communicates with the valve 2| on Fuelgas and oxygen flow to the valve 22 through conduits similar to the tubes 23, 24 and indicated bythe same reference characters. There is a valve 21 in each of the tubes 23, 24 for adjusting the flow of fuel gas or oxygen.

The'shut-oif valves 2| and 22 are normally closed, by spring or weight bias, and are opened by upward displacement of valve-operating plungers 28 and 29, respectively. The plunger 23 is displaced by a cam 30 secured to a cam shaft 32 that is rotated by a timer 33. Another cam 34 secured to the shaft 32 displaces the plunger 29. The torch block II has a distributing chamber 36 from which quenching fluid, such as water, is discharged through jet orifices 31 that open through the bottom face of the torch block.

'The quenching fluid is supplied through a pipe 39, shut-off valve 39, and tubing 40. The i-shut- 2, the view being the mass of the work-piece much greater at its the torch II is placed in the position shown in Fig. 1. v

The timer 33 is started and the cam 34 opens the valve 22 and causes gas to flow to the flame jet orifices I9. The jets from these orifices are lighted and heat the metal in the region of the flange 45. After a definite time interval, the cam 30 opens the valve 2| and permits gas to flow to the flame jet orifices I8.. The jets from these orifices are ignited by the other flames andthe inside of the work-piece is heated by all of the flames. The work-piece is rotated rapidly during the entire time that it is being heated in order to distribute the heat uniformly around I e entire angular extent of the inside surface.

' The cams 30 and 34 are so designed that with a given speed of rotation of the shaft 32 by the timer 33, the work-piece 44 is heated above the critical temperature of the metal for a predetermined depth, and for a uniform depth along the entire width of the work-piece because the additional heat put into the work-piece in the region of the flange 45 compensates for the heat lost by conduction into the additional mass of metal at the left end of the work-piece. The time that the cams 30 and 34 hold the valves 2I and 22 open depends upon the heating effectiveness of the torch. Each of the flame jets is a separate heating agency and the intensity of the flame systems and the heating effectiveness of the torch depend not only upon the size'of these flames but upon how closely they are spaced.

The cams coordinate the heating time with the intensity of the flame systems toobtain the necessary heating of the work-piece, the set of cams being designed for a particular work-piece that is produced in quantity.

As soon as the cams 30 and 34 have turned far enough to cause the valves 2I and 22 to close,

.the cam 42 immediately opens the valve 39 and causes fluid from the quenching jet orifices 3'I to cool the rapidlyrotating work-piece quickly and produce the desired hardness.

The application of this invention to a progressive flame hardening operation is illustrated in Fig. 2. A self-propelled torch carriage 48 has front wheels 49 driven by a motor 50, and rear wheels 5I, that run on rails 52 attached to a supporting table 53. The carriage travels along the track at preferably uniform speed.

A torch-supporting bar 55 slides in a bearing block 56 on top of the carriage. A rack 51 extends along the lengthof the bar 55 and the bar is shifted lengthwise in the bearing block 56 by a pinion that meshes with the rack and that is turned by a shaft 59. There is a hand-wheel 60 at the upper end of the shaft 59.

A bracket 62 near one end of the supporting bar 55 is connected to a torch block 63 and holds the torch block 53 spaced from a work-piece 64. The block 63 -extends across as much of the width as is to be hardened, which is the full width of the work-piece 64 in Fig. 2.

The structure of the torch block 63 is shown in Figs. 3 and 4. There are four parallel distributing chambers 66, 61, 68 and 69 extending lengthwise in the torch block for substantially the entire length of the block. A row of jet orifices II, 12, I3 and 14 extend from the chambers 66, 61, 68 and 69, respectively, and through the bottom face of the torch block 63 as shown in Fig. 4. The chambers 56, 61, 58 and 69 are at different levels in the torch block to permit the rows of jet orifices to be located closer together.

' A mixture of oxygen and fuel gas is supplied to the distributing chambers 66 and 68 through vertical passages 16 and 18, respectively, in one end of the torch block, and a similar mixture is supplied to the chamber 61 through a vertical passage TI at the other end of the torch block.

Quenching fluid, such as water, is supplied to the distributing chamber 69 through a passage I9 in the end of the torch block with the passage 11. a The supply of fluids to the torch 63 in Fig. 2 is controlled by cam-operated valves similar to those shown in Fig. land the pipes and tubing and gas-flow adjusting valves are indicated by the same reference characters as in Fig. 1. These valves are housed within the front of the carriage 48 in Fig. 2,-and there are three gas shutoff valves instead of two as shown in Fig. 1. The valves are identical, however, andthe .additional gas line is indicated by the reference character 8|. The tubing I5, I6, 8| and 49 connects with the top of the torch block 63 in register with the passages I], I8, I6 and I9, respectively.

The cams that control the supplyoffluids to the tubing I5, I6, 8| and 'are on a common cam shaft 32, but instead of a-timer, such as shown in Fig. 1, the cam shaft 32 of Fig. 2 is the displacement of the torch carriage-and the valves are operated when the carriage and torch reach predetermined positions along their course of travel regardless of the speed at which the carriage moves. v

The particular shape of the cams used to operate the valves on the torch carriageof- Fig. 2

will be evident from the operation illustrated in Figs. 5-9.

During'the first part of the hardening operation the torch block 63 moves to the right across the top of the work-piece 64 with flame jets I3 issuing from the third row of orifices I3 and quenching .jets I4 issuing from the fourth row of, orifices 14. .No gas is supplied. to the first and second rows of orifices II and I2.

Fig. 6 shows the torch 63 as it approaches the section where the thickness of the work-piece begins to increase. At this location the cams cause the second row of orifices I2 to be supplied with an oxy-fuel gas mixture and flame jets I2 are lighted and increase the-heating effectiveness of the torch to compensate for the added heat loss by conduction to the additional mass of metal.

In Fig. '7 the torch is shown as it reaches the cams to close the valve through which the oxyfuel gas mixture is supplied to these flames.

;'-When the torch reaches a section where the The torch 53 h hree rows of heating flame is illustrative only, Twoor four, or even e groups of flames can be used, and itis not necessary that the groups be arranged in separate rows, Forfxarnple, alternate jets of a single row might be supplieddfrom separate distributing chambers and comprise different groups. The number of flames in the different. groups need not be the same. .Where the thickness of the work increases gradually, it isdesirable to increase the heating effectiveness of the torch by smaller increments than is possible with the torch 63 where the turning-on of the second group of flame jets doubles the number of flames. For a rather rapid and very large change in section, as in the workpiece 54, large increments'in the flame system are desirable. c

. The cams controlling the flames of the torch 63 in Figs. 2-9 are designed to vary the heating effect of the torch in a manner that compensates for the increase in the'massof metal in the center of the work-piece, andthat produces a substantially uniform depth of hardness along the full length of the metal treated by the torch.

Various changes and modifications can be madein the invention, and some featuresof the invention can be I claim: I

1. The method of flame hardening a metal work-piece, which method comprises heating a section of the work-piece above its critical temperature by applying intense heat to the surface of that section with a number of separate heat used without others.

' sources, starting the operation of some of said heat sources ahead of others to apply heat for longer periods to regions-where the mass of the work-piece is heavier than at other regions, and quenching the work-piece while it is heated above its critical temperature.

2. In the flame hardening of a metal workpiece, the improvement which comprises heating the section to be hardened by means of heating agencies applied simultaneously along the entire length of said section until the metal is heated above its critical temperature for a predetermined depth, but subjecting regions where the workpiece is of greater thickness to suflicient preliminary local heating to compensate for and reduce the addition conduction losses to the mass of metal in the region of greater thickness so that the work-piece is heated above its critical temperature for a substantially uniform depth by the simultaneous action of the heating agencies.

3. The method of flame hardening a metal work-piece that is not of uniform thickness throughout the length of the section to be-hardened, which methodcomprises heating the regions of greater thickness flrst by local application of oxyacetylene heating flames to the surface of the work-piece at the thicker regions, subsequently applying oxyacetylene heating flames to the remainder of the surface of the section to be hardened while continuing the heating of the thicker regions, coordinating the time and intensity of the heating at different regions so that the entire section to be hardened is heated above the critical temperature of the metal for a substantially uniform depth at approximately the same time, and-with'the metal at this elevatedtemperature applying-quenching jets to the entiresection. v

'4. The method of hardening a generally cylindrical work-piecethat is'o'f non-uniform wall thickness, which methodcomprises rotating the work-pieceabout its aids during the-entire hardening operation, "applying heating flames first to the the surfacewhere the'wallis of greatest thickness, and subsequently to the entire length of the wall to be hardened with the time and intensity'of the heating at the different'regions coordinated to heat thedifierent parts of thewall above the critical temperature ofthem'etalfor a substantially uniform depth at approximately the same time, discontinuing the heating-and immediately thereafter applying I a quenching fluid to'the rotating work-piece throughout the length of the wall to-be hardened. 1 r

5. The method of flame hardening ametal work-piece that is not of uniform thickness throughout the length of the section-to be hardened, which method comprisesproducing relative movement of the work-piece and a systeni of flame jets that extend transversely of the direction of said movement, disposing the-flame jets so that some of said flame jets heat thesame portion 'of'the work-piece duringfsaid relative movement, supplying fuel for different .groups .of the flame jets from'separate-distributing chambers, changing .the heating effectiveness of the system of flame jets by extinguishing "certain of the flame jets during the heating operation, causing the flame jets to be extinguished byshutting off fuel toxthe'distributing chamberythat supplies the group to which those flame jetsbelong, and controlling the extinguishment of the flame jetsin accordance-with a predetermined sequence that compensates for differences in heat losses at regions of the surface where the underlying metal of the work-piece is of different thickness,

6. The method of flame hardening a workpiece that varies in thickness along its length, which method comprises progressively moving at a substantially uniform speed a system of heating flames along the length of the work-piece with a plurality of said heating flames in positions to heat the same portion of the work-piece during themovement ofsaid system lengthwise of the work-piece, following said system of heating flames closely by a system of quenching jets, and increasing and decreasing the number of heating flames in said system in accordance with changes in the thickness of the work-piece.

7. The method of rogressively hardening a work-piece comprising moving a multi-j et system of heating flames along the length of the workpiece with the flame jets in a plurality of rows extending transversely of the direction of their movement along the work, following close behind the heating flame jets with a transversely extending row of quenching jets, and varying the heat developed by the flame system by cutting off the supply of fuel to different numbers of groups of the flame jets to compensate for various reductions in the thickness of the work-piece at regions along its length, and choosing the flame jets for extinguishment so as to leave the system of heating flames substantially unchanged in length transverse of the work-piece.

8. In flame hardening apparatus, torch means with a number of groups of jet orifices for direct- 'diflerent directions and a A ing heating flames against a section of a workpiece, said torch means having separate distributing chambers tor the respective groups of flame jet orifices, a shut-oi! valve controlling the supply or fuel to each or the separate distributin a 9. Flame hardening. apparatus including incombination torch means with groups of flame jet conduits.

series with all ofsaid 12. Inailame hardening apparatus, a torch block for heating'a section or a-work-piece two rows of Jet orifices opening through the top race of the torch block, one row extending "longitudinally and the other-transversely on thetorch pendent shut-oi! valves in' block, separate distributingchambers for su'pplyinggas to each of said rows of jet oriflesgseparate valves for controlling the suppig' oi. gas to 1 each or said chambers, and means for operating orifices and a separate distributing chamber for each group or orifices, a valve for controlling the supply of gas to each distributing chamber, a cam associated with each of the valves for causing that valve to open and close, said cams being shaped and related with each other in accordance with variations in the thickness of a particular work-piece that is to be hardened, and

i automatic means for rotating the cams in unison and at a speed correlated with the heating operation to vary the heat developed by-the t'orch means in a manner that compensates for, differences in the conduction heat losses at regions of diflerentthickness.

10. Flame hardening. equipment including a torch-block with separate distributing chambers therein extending in dlfierent directions, and a group of jet orifices opening from each of said chambers, and a separate shut-oi! valve for controlling the supplyo! gas to each chamber.

11. Flame hardening equipment including a torchblock with three or more separate distributing chambers therein, some 01 which extend in opening'trom' each or said chambers, a conduit for supplying quenching fluid to one of the distrib-v uting chambers, and other conduits for supplying fuel gas to theother chambers, and inde'- orifices supplied with gas from different distributing chambers, valves'controlling the supply of gas to the respectivechambers, means for moving the torch means. and means responsive to the displacement or the torch lengthwise or a work-piece for operating the valves, said means including oneor morecams'designed to control the valves in accordance with variations in the thickness of the work-piece.

14. Flame hardening equipment including in combination a support, means carried by the support and comprising a number of heating agencies for heating a work-piece; a plurality of said heating agencies being in positions to heat the same portion of the work-piece during movement of the support lengthwise of the work-piece, mechanism for moving the support lengthwise alongthe work-piece, and means responsive to such movement of the. support for controlling the operation of the heating means to cause difierent numbers of said agencies to heat'the same portion of the work-piece at diflferent recom: J. cRovvE,

DISCLAIMER-f .2,282,94 2. +-John J. fi-owg we'stfield JQ Fun n HARDER-1N6; Petent dated May 12 1942. Disclaimer filed June 18, 1943, by the eseignee, Air Reduet'ion Company, Inorporated.

Hereby enterethis disclaimer to claim-10 of said patent; '1 IOfliciqlGwafla July 1;,194a1e I

Images