US2487974A - Process of continuously thermochemically scarfing a series of elongated steel bodiesand apparatus therefor - Google Patents

Description

5. B. KIRK R m A u s LE T. CD O MB E R HLO EF OEE M R E H BE TM H T SNA U OLA U N P. IYFA O m m E S A E 2 eets-Sheet 1 Filed y 28. 1945 INVVENTOR sTANLEY B. KIRK TORNEY s. B. KIRK 2,487,974 PROCESS OF CONTINUOUSLY THERMOCHEMICALLY SCARFING Nov. 15, 1949 A SERIES OF ELONGATED STEEL BODIES AND APPARATUS THEREFOR 2 Sheets-Sheet 2 Filed July 28. 1945 INVENTQR STANLEY B. KIRK ATTORNEY I terrupting Patented Nov. 15 1949 7 UNITED STATES PATENT OFFICE.

2,487,974 PROCESS OF CONTINUOUSLY THERMO- CHEMICALLY SGARFING A SERIES ELONGATED STEEL BODIES AND APPARA- TUS THEREFOR.

Stanley B. Kirk,

New Rochelle, N. Y., assignor I 4 to The Linde Air. Products Company, a, corpusration of Ohio Application July 28, 1945, Serial No. 607,647

8 Claims. (01. 148-9.5)

This invention relates to the art. of thermally conditioning metal bodies, and more particularly Objectionable defects which occur on the surfaces of steel blooms, billets, etc., have heretofore been removed by thermochemically desurfacing or scarring such surfaces while the hot steel bodies are in transit on a rolling mill conveyor'from one roll stand to the next. Inapparatus used for this purpose, it has been impracticable to desurface blooms and billets of relatively short length, e. g., four to six feet in length. This has been due in part to the fact that,,during the desurfacing,

such short-length bodies cannot be properly supported and propelled by the rolling mill conveyor. Longer bodies have been desurfaced one at a time 'in the apparatus heretofore used, which has involved manipulations and interruptions, both at the beginning and at the end of the thermochemical clesurfacing operation on the longitudinal surfaces of each body. First, the front or approaching end of the body and the desurfacing blowpipe heads must be properly positioned relatively to one another to start the desurfacing; then the preheat gases are turned on to preheat'a starting zone, whereupon the desurfacing oxygen V is turned on; and finally all gases are turned off after the body has been desurfaced longitudinally to its other end. These manipulations are repeated in desurfacing each of a succession of bodies.

In the desurfacing of relatively long steel bodies of rectangular cross section, for example, it has been the practice to set the blowpipe heads initially so that they will surround and bear against the four sides of a billet or other steel body when the front end of the latter reaches a starting position. Consequently, it has been necessary to start the'desurfacing at a preheated zone spaced 2. short distance rearwardly from the front end of the body, which leaves short undesurfaced areas adjacent the front end of the body. This undesurfaced end of the body usually is removed by cropping, in order to provide a completely desurfaced body. Such cropping and the resulting scrapping of metal are objectionable,

and this would be especially so in similarly processing metal bodies of short length and those thermochemically from a series of metal bodies;

to provide an improved process and apparatus thermochemically desurfacing relatively longer, metal bodies for short, as well as the usual 'without interrupting the continuity of the desurfacing operation, especially when the bodies are at a rolling temperature and are being propelled from one roll stand to the next roll stand in a rolling mill; and to provide an improved process and apparatus adapted to thermochemically condition the longitudinal sides of metal bodies completely from end to end.

The above and other objects and the novel features of this invention will become apparent from the following description taken with the accompanying drawings, in which:

Fig. 1 is a perspective View of a billet-desurfacing apparatus embodying this invention and adapted to perform the improved 'desurfacing process;

Fig. 2 is a central vertical cross-sectional View through two of the desurfacing blowpipe heads and the panel which carries them, also illustrating a billet and some of the rolls which straighten successive billets, align them with the throat or space defined by the blowpipe heads, and propel and guide them past the heads; and

Figs. 3 through '7 are fragmentary views in side elevation of a portion of the apparatus, illustrating the operation thereof.

According to this invention, the steel billets'or other metal bodies to be desurfaced or conditioned are propelled lengthwise and in end-to-end contact through a throat or space defined by a group of desurfacing blowpipe heads extending around the path of the billets. These blowpipe heads, during operation, continuously produce or discharge preheating flames and desurfacing oxygen streams which are directed obliquely transverse zones of the longitudinal sides of the series'of billets as the latter are propelled through the space defined by the desurfacing heads, to progressively remove a layer of surface metal from each side of every billet in the series without interrupting either the-preheating flames or the desurfacing oxygen streams and without interrupting the movement of the series of billets past the blowpipe heads.

surfaces are irregular, gaps may occur between the successive substantially coplanar billet sides,

in which event the molten slag and desurfacing reaction will not effectively carry across a gap to the succeeding billet side. Under such conditions. the continuity of the desurfacing operation is maintained by automatically introducing suitable adjuvant material, such as finely-divided metal adapted to increase the intensity of the preheat,

into the reaction zones when the preheating flames and oxygen streams cross such gaps and areapplied to the front end edges of the succeeding billet sides. Such adjuvant material desirably also is introduced as an aid to quickly start the desurfacing reaction at the front end edges of the first billet in the series. In each instance,

therefore, the longitudinal sides of every billet in the entire series are completely conditioned by the continuous desurfacing operation; hence no time is lost nor gas wasted in manipulating each billet and in repeatedly turning on and shutting off gases, or in moving the desurfacing heads inward toward the billet sides at the entering end of each billet and outwardly after each billet has. passed through the machine, and it is unnecessary to crop and scrap undesurfaced ends of billets.

A typical apparatus embodying this invention is illustrated in the drawings. As shown, such apparatus is constructed and arranged to condition or desurface all four longitudinal sides of a series of steel billets B of square cross-section as they are propelled lengthwise in end-to-end abutting relation past a group of four desurfacing blow.- pipe units D movably mounted on a stationary supporting panel P. The [blowpipe unitsare arranged perpendicular to one another so that their inner billet-engaging faces will define a square space or throat registering with a square hole I0, extending through the panel P, the throat and hole together providing aligned passages in the path of the billets.

Each blowpipe unit D is constructed to produce and deliver a wide preheating gas flame and a wide oxidizing gas stream obliquely against a lon-' gitudinal side of the passing billet B, to preheat and desurface successive zones extending across the side of the billet. For example, each blowpipe unit may be generally similar to the one disclosed in Bucknam Patent No. 2,362,536 issued November 14, 1944. The desurfacing heads are prefer-' ably mounted by means of T slots or dovetail slides on the plate P and stops preferably are provided for limiting inward movement of the heads such as, for example, collars or heads on the spring guide rods as indicated in Fig. 2. Yieldable means, such as springs II or pneumatic devices, may be arranged between abutments I2 on the panel P and the outer end of each blowpipe unit to yieldingly press the inner face of the blowpipe unit against a side of the billet; and the inner forward corner of each blowpipe unit may be rounded as at I3, to facilitate the entry of the. first billet of the series into the throat formed by the group of blowpipe units. This free floating arrangement of the blowpipe heads and their rounded corners enable the heads to automatically accommodate themselves to minor deviations of the billet sides from a straight path as they move past the blowpipe heads.

Suitable mechanism is provided to propel the series of billets B past the blowpipe heads D, to straighten the billets before they reach the blow pipe heads, to properly support the billets and maintain them in end-to-end abutting relation while they are passing the blowpipe heads, to maintain their corresponding sides in coplanar relation, and to guide the billets accurately along a path extending through and aligned with the throat formed by the blowpipe heads. As shown, this is accomplished by two substantially similar sets of rolls, one set being located in front and one set behind the panel P, each set being generally similar to a conventional straightening roll stand. The front set of rolls may comprise pairs of Vertical and horizontal power driven rolls pref- 0 erably arranged so that the rolls nearest the desurfacing heads are horizontal to provide support for short billets, the distance between supporting rolls before and after the desurfacing heads therebybeing short. The front pair of rolls I 4 thus may be vertical, the next pair of rolls I5 horizontal, the third pair of rolls I6 vertical, and the last pair of rolls horizontal; the rolls of each horizontal pair I5, I! being spaced apart vertically sulhcient to engage the upper and lower sides of the billets passing between them, and the rolls of each vertical pair I4, I6 being spaced apart horizontally to engage the opposite vertical sides of the billets. The supporting frame, bearings and roll driving mechanism may be conventional and arenot shown in the'interests of clearness. The rear set of rolls comprises two pairs of horizontal rolls I8, I8 and two pairs of vertical rolls 2B, 29; the rolls of each horizontal pair being spaced apart a suflicient distance vertically to engage the upper and lower sides of the billets passing between them, and the rolls of each pair of vertical rolls being spaced apart a sufilcient distance horizontally to engage the opposite vertical sides of the billets passing between them.

Each roll of the two sets of rolls desirably is positively and continuously driven in the direction of the indicating arrows by suitable powerdriven mechanism, including motors X and Y though for some purposes the rolls of the rear set may be idlers, i. e., not power driven. The lower horizontal rolls serve to support the billets and cooperate with the upper horizontal rolls to properly support and maintain the billets, even the shorter lengths, in a horizontal position during the desur'facing operation and to positively drive the billets through the machine at desurfacing speed. The passes between each pair of both the front. and rear sets of rolls are so arranged'and aligned that together they provide a fixed horizontal billet path which is coaxial with the hole Ill through the panel P and with the throat formed by the blowpipe heads, thus insuring that the series of billets will be accurately guided and propelled past the blowpipe heads and through-the machine. The front and rear sets of rolls are preferably suitably aligned with conveyor means for feeding billets to and from the machine, for example, power driven conveyor rolls I9 of an inlet conveyor and rolls 2i of a discharge conveyor.- To assist in keeping the incoming billets in end-to-end abutted relation the rolls I9 may be driven by suitable powerdrivenmechanism including a motor Z at a slightly faster speed than the rolls I I.

Both the front and rear sets of rolls frictionally "engage the several sides of the billets to propel the latter at a constant selected desurfacing speed while maintaining the billets butted end-to-end; and to further insure this abutting relation the rear set of rolls may be driven at a slightly slower speed than the front set, or the front set of rolls may constitute the sole power-driven billet pushing or propelling means of the machine while the rolls of the rear set operate'as idlers and primarily assist in supporting and guiding the billets. Moreover, the horizontal and vertical rolls of the front roll set cooperate to straighten the billets and remove any camber, bends, or twists therein before the billets are presented to theblowpipe heads.

Where the billet end faces are square, i. e., perpendicular to longitudinal sides of billets, the desurfacing reaction usually will advance smoothly and with no interruption across the joints between the abutting ends of the series of billets. However; to insure efficient and uninterrupted desurfacing across the joints between the abutting ends, particularly when the billet end faces are not square and gaps occur between opposed edges at the joints, the apparatus includes suitable means operable automatically to introduce a-small quantity of adjuvant material into the reaction zone at the time that the mutually abutting ends pass the blowpipe heads, and also at the moment that the preheating flamesand desurfacing oxygen streams impinge against the sides of the first billet in the series. 1 I

As shown, the means for supplying powdered adjuvant material'to the reaction zone includes a container and dispenser H for'the adjuvant material, such as finely-divided iron, steel, manganese, ferromanganese, or suitable mixtures thereof. In order to deliver the powdered adjuvant material to and distribute it along the reaction zone, a source of fuel gas such as acetylene under pressure communicates by apipe 22 with the interior of the dispenser H, and the powder-laden stream of fuel gas is delivered from the dispenser through acommon supply pipe 23 and flexible branch pipes 24 to the fuel gas passages in the several blowpipe heads H, to be discharged from the fuel gas orifices of the latter into the reaction zones extending across the sides of the billets, or the powder-laden gas streams may bedischarged from separate rows of orifices parallel to the conventional oxygen and preheating gas orifices of the heads.

The common supply pipe 23 is provided with a control valve V which is connected to be mechanically operated by a solenoid 25. The solenoid is, in turn, connected to be electrically operated'by a time delay device T which is under the control of switches 26 and 21, the electrical control circuit being connected to a suitable source of current supply by insulated conductors LI and L2.

, The limit switches 26 and 21 are responsive to the operation of joint'detectors 28 and 29, respectively, which, in the illustrated example, include triggers 30 and 3| pivoted to supports 32 and 33 above the path of the billets and in advance of the scarfing machine S. Thetriggers 3t and 3| ride on the top surfaces of the billets as they move toward the desurfacing machine,

in which case the switch 21 "remains closed so that when a gap G between adjacent bodies B is presented under the trigger 30' the latter falls below a certain level and causes a vertical slide 34 to actuate a lever 35 of the limit switch 26 'device T which, in turn,

without interruption to the desurfacing operation. My, The powder contr ol'yalve V should be closed both when no billets are being conditioned, Fig. '7,

and when there are no gaps or no low or high portions at the joints adjacent the abutting ends of successive billets, also while the longitudinal sides of the billets are being conditioned, Fig. 4.

However, in order to condition the first billet in the series, Fig. '3, as well as all others, completely from end-to-end, the valve V must be opened at the instant that the leading end of the first billet reaches the preheating flames and oxygen streams discharged from the blowpipe heads; and the valve V also must open whenever a gap or a low or high edge at any joint between successive billets reaches the preheating flames and oxygen streams. r

As shown in Fig. 3, when the first billet is being advanced toward the scarfing machine S, the billet first engages and elevates the trigger 3|, so that the normally closed switch 21 remains closed.

Prior to the arrival of the billet B to a position under the trigger 30, the latter, being unsupported, falls to its lowest position, carrying with it the slide 34 and the cam 36 which is mounted on the slide. In this position of the cam 36 the switch 26, which is normally open, remains open so that the timing device T is not energized.

As shown in Fig. 4, however, when the billet B supports the trigger 30 at its normal operative level, the slide 34 is elevated, causing the cam 36 to momentarily close the normally open switch 26, which results, by virtue of the operation of the time delay device, in opening the powder valve V at the proper time when the leading edge E of the first billet is in proper position to start the desurfacing operation. A flying start results.

As shown in Fig. 5, a gap G in a'jOint between adjacent billets, causes the trigger 30 to drop, as described above in connection with Fig. 1, so that switch 26 is momentarily closed, resulting in the delivery of a burst of powder when the gap is presented to the Scarfing machine S. r

In case the joint between adjacent billets has an elevation or transverse-ridge R, asshown in Fig. 5A,'the switch 26 is also closed by virtue of 60 As shown in Fig. 6, when the last billet B passes from under the trigger 3|, the latter falls to its lowermost position, automatically opening the normally closed switch 21, which is in series circuit relation with the normally open switch 26. Thus, the subsequent tripping of the trigger 30 when it is no longer supported by the billet, and the momentarily closing of the switch 26 does not result in energizing the circuit L -I, L-2. I

The time or distance interval metering device in the timer T may be synchronized-by suitable means electrically or by gearing with the rolls in front of the desurfacing heads in order that the valve Vc-will be energized at the right time irrespective of variations of speed 01 the rolls and billets. When thefirst billet of a series enters the machine for treatment, the desurfacing gases for the-heads D should be turned on. This can be done by a manual control.

It Will be understood that slag-removing water jets J may be provided between the scarfing machine .S and the rolls [6 and I! to protect the latter. Complete slag removal transversely of the workpiece may be obtained by the use of slagremoving water.

The apparatus embodying thisinvention may be inserted in the conveyor table between roll stands, or it may be operated independently of a rolling mill. While the invention is shown as applied in .the desurfacingof metal bodies, novel features of this. invention are also applicable for oxy-gas cutting and for thermally conditioning metal bodies. Moreover, various changes may be made in the machine disclosed herein without departing from the invention or sacrificing its advantages.

I claim:

1. Apparatus for thermochemically scarfing surface metal continuously from a series of elongatedsquare-ended steel bodies of similar crosssectional shape, which comprises conveyor means for advancing the bodies in succession along a horizontal path in the direction of their length,

thermochemical scarfing means for applying preheating flame and a stream of oxidizing gas obliquely against successive surfaces of such bodies, pairs of vertical and horizontal body straightening rolls mounted both directly in front and in backof said scarfing means for transversely compressing the bodies, motor means for power driving at least the straightening rolls in front of said scarfing means, and separate motor means for power driving said conveyor means at a faster rate than said driven straightening rolls,v

so that the bodies are longitudinally compressed in abutting end-to-end contact with one another as the bodies are scarfed by said scarring means without interruption on account-of the joints between such bodies.

2. Process of thermochemically scarfing. surface metal continuously and without any jointinterruption from a series of elongated steel bodies of'similar cross-sectional shape, which comprises squaring the ends of such bodies, support-;

ing the bodies in abutted end-to-end. relation, compressing the bodies longitudinally thereof, maintaining the bodies in axial alignment, moving the bodies continuously through a scarfing station, at such station progressively applying5g55 preheating flames and streams of oxidizing gas obliquely against and lengthwise of successive coplanar longitudinal surfaces of said moving bodies to produce an oxidizing reaction which thermochemically scarfs surface metal therefrom longitudinally of the bodies, at least some of said bodies having gaps between them; automatically detecting any gaps between such bodies before the joints are subjected to such reaction, and increasing. the intensity of the reaction when a joint" with a gap is subjected to such reaction by adding a burst of combustible metal powder consisting essentially of iron to the streams of oxidizing gas, so that the scarfing action is continuous and proceeds smoothly from onebody to the next succeeding body.

3. Process of' thermochemically scarfing surface metal continuously and without any jointinterruption from a series of elongated steel bodies of similar cross-sectional shape, which com prises squaring: the-ends of such bodies, conveying said bodies in succession along. a horizontal path-in the direction of their length, longitudinally compressing said bodies so that the joints are positively closed and the abutting end edges are in mutually contacting metal-to-metal rela- .tionship,: transversely compressing the bodies vertically and horizontally directly in front and in back of a thermochemical scarfing station to inl-sure straightness thereof and smooth continuity --surface metal from aseries of metal bodies, such .as steel billets, comprising the combination of means for supporting and propelling said bodies simultaneously in the direction of their length in end-to-end contacting relation, a plurality of blowpipe heads adapted to discharge oxidizing gas streams against the longitudinal surfaces of said bodies for removing surface metal from all of the surfaces in a single pass, means responsive to the joints betweenadjacent bodies for initiating a time delay, time delay means for operating a powder valve, and means responsive to the operation of said powder valve for supplying adjuvant material to said joints as they approach said desurfacing heads, so that the bodies are suceessively desurfaced without interruption between adjacent bodies.

5. Apparatus for thermochemically desurfacing a series of elongated metal bodies, such as steelbillets, comprising an oxygen scarfing machine including a plurality of desurfacing blowpipe heads having nozzle protective shoes shaped to provide a mouth having an opening for the entrance of: said bodies, and means for supporting, propelling and straightening said bodies as they pass through the scarfing machine, comprising vertical and horizontal rolls mounted both in frontand in back of said scarfing machine for straightening each body, said rolls being closely spaced and driven at fixed speeds.

6. Apparatus for desurfacing a series of metal bodies, such as steel billets, of relatively short length, comprising means for supporting and continuously propelling said bodies in the direction of their length and in end-to-end contact, comprising a plurality of sets of supporting, propelling and straightening rolls which serve to pro- .pel'the bodies along a-relatively fixed axis and --disposed adjacent the longitudinal sides of the bodies when so propelled, the number of said heads being sufficient to desurface all of said sides in one pass, means supporting said heads for limited movement in response to variations in the dimensions of the bodies, and means for increasing the intensity of the thermochemical reaction at the joints between adjacent bodies, so that the desurfacing operation bridges such joints without interruption, said last-named means in eluding means for supplying adjuvant material to the reaction zone and means for feeding such material momentarily, comprising a Valve, a timing device for operating said valve, and means for initiating operation of said timing device, comprising a joint detector disposed in the path of said bodies in advance of the scarfing machine.

7. In apparatus for scarfing a body progressively from one end to the other thereof, the combination comprising, a scarfing station, vertical and horizontal rolls located both in front and back of said station for guiding a series of bodies through said station, said vertical and horizontal rolls cooperating to straighten each body, means for continuously driving said rolls to move said bodies at constant speed, thermochemical scarfing means located at said station, said means comprising work heating means which is adjustable, a work detector located in advance of said station, and means responsive to said detector for adjusting said work heating means, including means for timing the adjustment of said work heating means in accordance with the arrival of the work with respect thereto, so that the bodies are scarfed longitudinally as they move continuously through said station.

8. In apparatus for scarfing the surface of a metal body progressively from one end to the other end thereof, the combination comprising, a scarfing station, straightening rolls for guiding a series of metal bodies through said scarfing station, means for driving said rolls to move said bodies at constant speed through said scarfing station in abutting end-to-end relation, thermochemical scarfing means and a heat increasing instrumentality located at said station, a joint detector located in advance of said station, and means responsive to said joint detector for operating said heat increasing instrumentality, including time delay means for timing such operation of said instrumentality in accordance with the arrival of the joint with respect thereto, so that the scarfing action continues across each joint between the bodies as they move continuously through the scarfing station.

STANLEY B. KIRK.

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

UNITED STATES PATENTS Number Name Date 1,194,617 Goss Aug. 15, 1916 2,016,414 Cramer Oct. 8, 1935 2,030,842 Anderson Feb. 18, 1936 2,067,972 Leech Jan. 19, 1937 2,072,121 Montgomery Mar. 2, 1937 2,125,174 Jones July 26, 1938 2,189,753 Bucknam et al. .Feb. 13, 1940' 9 2,288,027 Schel1eri;;'i: June 30, 1942 2,290,290 Meincke July 21, 1942 2,309,096 Bucknam et a1 Jan. 26, 1943 2,312,418 Keller et a1. Mar. 2, 1943 2,312,839 Kullman et a1. Mar. 2, 1943 2,323,974 Bucknam et a1. July 13, 1943 2,325,638 Strickland Aug. 3, 1943 2,329,188 Denneen et a1 Sept. 14, 1943 2,362,536 Bucknam Nov. 14, 1944 2,366,787 Hoffman Jan. 9, 1945 FOREIGN PATENTS Number Country Date 344,057 France Aug. 25, 1904 641 Australia Mar. 18, 1926 of 1926 549,781 Germany May 2, 1932 OTHER REFERENCES Metals Handbook, 1939; pages 927, 928, 933, 934, 937; published by American Society for Metals, Cleveland, Ohio.

International Autylene Assoc. Oxy-acetylene Committee publications, sec. XIII, Flame Hardening by the Oxy-acetylene Process," 1940,

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