US2279564A - Apparatus for flame hardening tubular structures - Google Patents

Description

April 14, 1942. c, EMERY ET AL 2,279,564

APPARATUS FOR FLAME HARDENING TUBULAR STRUCTURES Filed Oct, 50, 1959 Patented Apr. 14, 3%42 Users" TUBULAR. STRUCTUR Frank C. Emery, Los Angeles, and Edwin F. Green, Lynwood, Calif., asslgnors to Axelson Manufacturing 00., Los Angeles, Calii., a corporation of California Application October so, 1939, Serial nascrsza 8 Claims.

Our invention relates to an apparatus for flame hardening the interior. surfaces of bores.

In many industries it is desired to harden the interior surfaces of bores on various pieces of machinery and the most effective means hereto! fore known for accomplishing this result has been to employ a case hardening process which is laborious and expensive and which process frequently leaves the hardened surfaces with scale or coatings of oxide which must be subsequently removed in order to provide smooth surfaces, particularly if the bores are to receive other machinery parts which move within the bores as is the case with engine and pump cylinders, linings. therefor, sleeves, bushings, and the like.

While it will be understood that our invention is obviously applicable to the treatment of bores in any machine elements or parts regardless of length and diameter of the bores, our invention is particularly useful in connection with the manufacture of oil well pumps, wherein the barrel of the pump is usually formed of a relatively long length (up to twenty or more feet) of relatively small bore and thin walled tubing (internal diameters whichrange upwardly from about one inch and the wall thickness of which may be It is therefore an object of our invention to provide an apparatus by which bores may have their internal surfaces flame hardened by a flame hardening process in which a burner may be bodily introduced into the bore to direct jets of flame against the interior surface of the bore and in' which a cooling medium is so introduced ahead of and behind theflame as to confine the application of heat to the surface to be hardened the flame hardening of bores inwhich the burner one-eighth of an inch or more). Thes barrels provide the pump cylinder within which reciprocates a pump plunger which must make sealing contact. It is therefore essential that the internal surface of the barrel be extremely smooth throughout its length, accurately sized throughout its length and present to the reciprocating.

plunger a hard, wear-resistant surface.

Though it is necessary to harden only the interior surface of any such bores, it is impossible,

when using the case hardening process, to accurately and uniformly control the distribution of heat through all parts of the metal surrounding the bore to avoid the building up of undesirable internal stresses which, for example in thin walled structures, will result in the warping of processes, it has been common practice to employ liners within the barrel constructed of a plurality of short sections of accurately sized tubing to provide the necessary accurately sized and hardened surface for cooperation with the pump plunger.

" is so constructed as to provide a plurality of jets directed radially against the internal surface of the bore to provide a substantial circle of flame extending about the cross section of the bore and confining the heated area in a direction longitudinal of the bore by cooling medium which is introduced ahead of and behind the flame jets.

Another object of our invention is to provide a burner of the character described in the preceding paragraph wherein the cooling medium is introduced through the burner and acts to cool I of the flame jets so'as to produce, in effect, ap'ai of spaced circles of cooling medium extending across the cross section of the bore and defining the gases supplied to theburner and to cool the burner itself and thereby avoid flash-backs or pre-ignition of the gases employed to produce the flame.

Another object of "our invention is to provide a burner as described in which the cooling medi- J um is ejected' from the burner. as two groups of spray streams, one group directed rearwardly of the flame jets and the other directed forward a short zone betweenthem within which the application of heat confined.

It is also an object of ourinvention to provide an apparatus ofthe character set forth in the preceding paragraph in which means is provided for rotating the device having the bore to be treated about a horizontally disposed longituto the surface of the bore is dinal axis while the flame is being passed therethrough to permit the use of water or other liquid cooling medium for both quenching and prevent-.

ing pre-heating.

Another object of our invention is to provide an apparatus as set forth in the preceding paragraph; wherein the cooling medium is introduced into the rotating bore to be treated as two sepathe interior of the tubing I, being supported upon a supporting tubular structure I. The tubular supporting structure I may be carried in the tool post upon the conventional lathe carriage but we have found it desirable to substitute a carriage construction 8 which includes a guiding means 9 resting upon ways In of the lathe bed II and adapted to he slid therealong. The carriage 8 preferably includes a downwardly depending portion l2 which carries a means engaging a conventional lathe feed screw [3 so that rotation of this feed screw will operate to advance the carriage 8 along the ways III to cause the burner 6 to pass at a uniform rate longitudinally through the tubing l.

The carriage 8 is provided with a manifold M into which is secured the tubular supportingstructure The'manifold l4 preferably includes the bore to control the depth to whichthe interior surface of the bore is heated to the desired temperature.

Itis a still further object of our invention to provide in an apparatus of the character set forth in the preceding paragraphs a means for adjusting the heat of the flame, the rate of travel of the flame through the bore, and the rate of flow of cooling medium to the heated portions of the bore to permit the control of depth to which the surface is hardened, the degree of hardness imparted thereto and the degree of tempering effected upon the hardened portions of the surface.

It is a further object of our invention to provide in an apparatus of the character set forth in the preceding paragraph a means for supporting a burner centrally of the bore as it is passed longitudinally therethrough.

Other objects and advantages of our invention will be apparent from a study of the foltails of construction.

Referring to the drawing, we have illustrated in Fig. 1 one form of flame hardening apparatus of our invention which is particularly adapted to the hardening of the internal surface of a long length, small diameter tube such as might be used for pump barrels. This apparatus is illustrated as including a means for supporting a relatively long length of small bore tubing I for rotation about its horizontally disposed longitudinal axis. The means for so holding and rotatting the tubing l is illustrated in Fig. 1 as comprising a conventional engine lathe 2, it'having been found that such a lathe is particularly adapted for this use, although it is to be understood that other types of apparatus capable of performing the desired functions would be equally and 5.

A combination burner and spray head't is mounted for longitudinal axial movement along a means for adequately mixing in the proper proportions oxygen, which may be delivered from an oxygen supply tank l5 by means of a flexible hose l6, and acetylene, or other combustible gas, which may be obtained from a gas supply tank I! and delivered to the manifold M by means of v a flexible hose i8.

Provision is also made in the manifold M for receiving, but keeping separate from the mixture of oxygen and acetylene, a cooling-medium, such as Water, which may be supplied thereto from a suitable supply 19 by means of fluid connections 20 and 2|. A control valve 22 is preferably interposed between the fluid supply lines 20 and 2| so that the rate. of flow of cooling medium may be adjusted. The control valve 22 is preferably formed as a small'carriage and includes means cooperating with the ways ill of the lathe bed.

ll to permit the control valve 22 to slide along these ways. The valve structure 22 is preferably connected by means of a bar 23, or similar connecting means, to the carriage 8 so that as the carriage 8 moves along the lathe bed H the control valve 22 is also caused to move therealong. The length of the bar 23 is so adjusted as to dispose the control valve 22 adjacent the burner 6 so that an operator disposed adjacent the control valve 22 may observe exteriorly the effects of the burner 6 within the tube l and control the amount of liquid flow in terms of what is observed.

We have illustrated in Figs. 2 and 3 the details of construction'of the preferred form of combination burner and spray head 6 and tubular supporting structure 1 therefor. The tubular supporting structure I preferably comprises a relatively thin walled tubing 24 within which is concentrically mounted a similar but smaller piece of tubing 25. The tubing 25 is so connected to the manifold M as to convey to the burner 6 the mixture of combustible gases which is received from the supply tanks I5 and H. The annular space between the exterior of the tubing 25 and the interior of the tubing 24 is connected within the manifold 14 to the liquid supply line 2| so that the cooling medium which is delivered thereby to the burner 6 surrounds the combustible gas which is contained within the tubing portion 25.

The combined burner and spray head 6 preferably includes a guiding or supporting portion 26 which is provided with an axially extending bore 21 adapted to receive the end of the outer tubing 24 and be secured thereto by any suitable means, such as brazing or silver soldering. The guiding and supporting structure 26 is provided with a pair of downwardly and outwardly directed feet Aburner head 3I is secured to that end of the:' supporting structure 25 which is opposite to that end secured to the tubing 24. .The burner head 3| is preferably provided with a large diameter cylindrical portion 32 and a small diameter cylindrical portion 33 which'are interconnected by a tapering or conical section 34. The enlarged cylindrical portion 32 is prefer-ably machined so as to provide an internal recess 35 which is" annular' inshape having an internal boss 35 disposed cen'trally. therein. The annular space 35 communicates with the bore 21 provided in the supporting structure 26 so that cooling medium which is conveyed through the annular space between the tubings 24 and 25 is conducted through the bore 21 and into the annular space 35.

A set of spray openings 31 comprising relatively small bore orifices are provided in the conical section 34 of the burner head 3| and communicate between the cooling medium space 35 and the exterior of the'burner. Each of the orifices 31 is directed forwardly at an angle to the axis of the tubular support I so that jets of cooling medium 38 which are discharged therefrom are projected forwardly and strike the interior surface 38 of the tubing I at a point in advance of the forwardend of the burner 8. A similar coacting set of orifices 39 is also provided which communicates between the exterior surface of the large diameter cylindrical portion 32 and the annular space 35. The orifices 39 are preferably directed rearwardly at an angle to the axis of the tubing I so that jets of cooling medium 48 discharged therefrom will strike the interior surface of the tubing I at a rearwardly directed angle thereto and at a position disposed to the rear of the orifices 39.

It will be observed thatas the tubing I is disposed with its axis substantially horizontal and is being continually rotated about this axis by the spindle driving mechanism of the lathe 2 that the jets of cooling medium 38 which are directed forwardly will impinge upon the interior surface 38 of the tubing I at a forwardly directed angle so as to operate to force a continuous stream A of the cooling medium forwardly along the tubing to be discharged out that end which is carried in the lathe chuck 3. In a similar manner, the cooling medium which is directed against the interior wall 38 of the tubing I by the jets 48 will be forced thereby in a continuous stream B rearwardly along the tubing I to be discharged out.

the end thereof which is carried by the-steady rest 5.

It will be apparent that the operation of the sets of jets 38 and 48 is to apply the cooling medium substantially uniformly to the entire interior surface. of the tubing I with the exception of a relatively short cylindrical zone disposed between the zones of application to the interior surface 38 of the jets 38 and 48. It is against this longitudinally limited zone of the interior of the tubing I that a multiplicity of individual flame jets M is directed. The flame jets 4| are each preferably disposed substantially normal to the axis of the tubing I, this disposition being obtained by providing a multiplicity of burner openings 42 which communicate between the exterior'surface of the small diametercylinder portion 33 and a longitudinal bore 43 extending therethrough. The bore 43 communicates with the interior of the gas supply tubing and extends through the cylindrical boss 36 to which the end of the tubing 25 maybe secured as bybrazing or silver soldering.

The number of openings 42 employed is pref- 'erably made equal to or a multiple of the number of sprayjet openings 31 employed, each of the openings 42 being disposed in staggered relationship relative to adjacent openings3l so thatthe flame jets 4I arecaused to pass between adjacent cooling median jets 38. The extreme forward end of the bore 43 may be closed by means of a screw plug "44 threadedly engaged with the forward end of the bore 43 and adapted to clamp a seal or gasket 45 against the forward end of the small diameter cylindrical portion 33. The plug 44 is preferably formed with a longitudinally extending boss 46 which projects into the bore 43 so that by selecting the diameter and for gases through the bore and jets 4I may be regulated to produce the desired throw of the names from the jets as well as to produce a steady, smooth, uniform flow of the gases therefrom. I

In operation, the apparatus is set up in the fashion illustrated in Fig. 1, :the proper propertions of oxygen and acetylene or other combustible gas are provided in the burner 8 and the burner ignited to provide the flame jets M. A flow of cooling medium is then started by means of the fluid control 'valve 22 and the tubing I is rotated and the feed screw I3 engaged to cause the carriage 8 to advance to the left, as illustrated in Fig. 1, and cause the burner 6 to enter and pass through the interior of the tubing I. As the burner 6 passes through the tubing, the cooling medium supplied by the jets 38 operates to'cool the portions of the tube which are disposed ahead of the flame jets 4| to prevent pre heating of the tube either by conduction through the metal or by the hot gases resulting from the combustion of the gases-supplied to the burner.-

It will be observed that as the burner 6 is ad vanced through the tubing, the flame jets 4| operate to heat that zone which lies between the two zones of application of the cooling medium flame jets 4I and operate to quench these heated I portions and harden the interior surface of the tubing in a well known manner. The cooling medium which is forcedout the rear end of the tube by the jets 48 operates to continually cool the hardened portions of the tube to prevent annealing or tempering of these portions. It has been found, however, that if the rate of flow of cooling medium is properly controlled the hardened portions of the tubing'may be reheated by conduction from the heated zone-toprovide a tempering of thesehardened portions. It will be observed that the amount of tempering which is provided may be readily controlled by controlling the rate of flow of the cooling medium to the burner.

Attention is also called to the fact that the depth to which the walls of 'the tubing l are heated to a temperature in excess of. the critical temperature depends upon the rate of gas flow to the burner 6 and the rate at which the burner is moved through the tubing, while the degree of hardness is dependent upon the severity of the body for withstanding shocks and impact loads.

Byemploying a burner of the character described herein by which the cooling medium surrounds the supply pipe leading to the burner and also comes into intimate contact with the burner, the combustible gas mixture and the burner are maintained at such low temperatures as to :prevent flash-backs and our burner can be successfully employed within tubes or bores having diameters in the order of one inch or less.

.It has been found that an operator, by experience, may observe and recognize the operating conditions as regards the depth to which the hardening of the tubing is carried and the degree of hardness thereof by observing 'the exterior of the tubing at the location of the flame 4| within the tubing. It accordingly lies within the interior surface .of said bore to heat a short cy-v lindrical zone to a temperature in excess of the critical temperature; means associated with said burner for directing a cooling medium against said interior and about the .entire periphery burner; and means associated with said burner for directing a cooling medium against said interior surface after it is heated to quench and harden said heated surface.

scope of this invention to centralize all of the poses of illustration, specifically described herein,

it will be understood by thoseskilled in this art that the principles of our invention may be readily employed for the flame hardening of the interior surfaces of other types of bores and for the effective treatment of other types of machinery in which the same problems are: presented, and

we, therefore, do not desire to be limited to any of the details illustrated and described herein,

except as defined in the appended claims.

We claim:. 1. In an apparatus for hardening the interior surfaces of bores in machine elements, the combination of: a burner; means for advancing said burner longitudinally through said bore; means on said burner for heating the interior surface of said bore to a temperature in excess of the critical temperature; and means associated with said burner for applying a cooling medium to said element within said bore on opposite sides of said burner to confine the heat to a short cylindrical zone and to quench and to harden the surface immediately after it is heated.

2. In an apparatus for hardening the interior surface of bores in machine elements, the combination of: a burner; means for advancing said burner longitudinally through said bore; means on said burnerior directing flame against the 3. In an apparatus for hardening the interior of bores in machine elements, the combination of: means for rotating said element about the longitudinal axis of said bore disposed horizontally;

a burner; means for advancing said burner longitudinally through said bore while said element is rotating; means for conveying a flame producing combustible mixture to said burner; means on said burner for directing flame against the interior surface of said bore to heat a short cylindrical zone to a temperature in excess of the critical temperature; and means associated with said burner for confining the he'atingeffect of said flame to said zone comprising means for directing a cooling medium against said interior surface and forwardly in advance of said zone; and means for directing a cooling medium against said interior surface immediately after it is heated to quench and harden the heated surface.

4. In an apparatus for hardening the interior surface of bores in machine elements, the comed surface immediately after. it is heated to quench and harden said surface; a conduit for conducting said cooling medium to the location of said burner; valve means in said conduit for controlling the amount of cooling medium conveyed to said burner to control the severity of the quench; and means mounting said valve means for movement with said burner exteriorly of the b'ore along the side of said element.

5. In a burner for use in flame hardening the interior of bores, the combination of: a head insertable in said bore for advancing movement longitudinally. therethrough; a gas passage in said head, a plurality of outwardly directed burner openings in said head communicating with said passage for directing flame against the interior surface of said bore included within a short cylindrical zone; a cooling medium space in said head surrounding said gas passage; one set of spray openings communicating with said medium space for directing a cooling medium therefrom against said surface and about the entire periphery thereof immediately behind said flame to quench and harden said surface after it is heated; and another set of spray openings also communicating with said medium space for directing said cocling medium therefrom against said surface and about the entire periphery thereof immediately in advance of said flame to prevent preheating thereof until said flame is brought into contact therewith.

6. In a burner for use in flame hardening the interior of bores, the combination of: a head insertable in said bore for advancing movement longitudinally therethrough; a gas passage in said head; a plurality of radially disposed burner openings in said head communicating with said passage for directing flame against the interior surface of said bore included within a short cylindrical zone; a liquid space in said head surrounding said gas passage; one set of spray openings disposed behind said burner openings communicating with said liquid space and directed rearwardly of said' flame openings for directing a cooling medium therefrom against said interior surface rearwardly of the advancing flame to quench and harden said interior surface after it is heated; and another set of spray openings also disposed behind said burner openings communicating with said liquid space and-directed forwardly of said flame openings for directing said cooling medium therefrom against said interior surface in advance of said flame to prevent pre-heating of the surface until said flame is brought into contact therewith.

7. In a burner for use in flame hardening the interior of bores, the combination of: a head insertable in said bore for advancing movement longitudinally therethrough; a gas passage in said head; a plurality of radially disposed burner openings in said head communicating with said passage for directing flame against the interior surface of said bore included within a, short cylindrical zone; a liquid space in said head surrounding said gas passage; one set of spray openings disposed behind said burner openings communicating with said liquid space and directed at an angle rearwardly of said burner openings for directing a cooling medium therefrom against saidinterior surface rearwardly of the advancing flame to quench and harden said interior surface after it is heated; and another set of spray openings also disposed behind said burner openings communicating with said liquid space and directed at an angle forwardly of and'between adjacent ones of said burner openings for directstantially radially extending gas openings com-' municating with said gas passage near the.opposite end thereof; plug means in said opposite end having means thereon projected into said gas passage to restrict the passage adjacent said openings for producing a uniform flow of gas therefrom; a cooling medium conduit surrounding said gas conduit and coupled to said body to pass a cooling medium about said gas'conduit and-into the interior of said burner body; and a plurality of circumferentially spaced spray openings extending outwardly through said body for thepassage of cooling medium, a part of said spray openings being spaced in staggered relation to the spacing of the gas openings and directed forwardly therebetween, the remainder of said spray openings being directed rearwardly.

FRANK C. EMERY. EDWIN F. GREEN.

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