US3367804A

US3367804A - Method and apparatus for quenching

Info

Publication number: US3367804A
Application number: US453925A
Authority: US
Inventors: Teplitz Alfred
Original assignee: United States Steel Corp
Current assignee: United States Steel Corp
Priority date: 1965-05-07
Filing date: 1965-05-07
Publication date: 1968-02-06
Anticipated expiration: 1985-02-06
Also published as: BE680468A; NL6606238A; DE1508451A1; GB1144204A

Description

Feb. 6, 1968 A. TEPLITZ 3,367,804

METHOD AND APPARATUS FOR QUENCHING Filed May 7, 1965 2 Sheets-Sheet 1 qll Attorney A. TEPLITZ 3,367,804

METHOD AND APPARATUS FOR QUENCHING 2 Sheets-Sheet 2 Feb. 6, 1968 Filed May 7, 1965 Alli PIE: 2 ll? AIR AIR

INVENTOR ALFRED TEPL/TZ Uit States 3,367,804 METHOD AND APPARATUS FOR QUENCHKNG Alfred 'Ieplitz, Pittsburgh, Pa, assignor to United States Eitcei (Iorporation, a corporation of Delaware Filed May 7, 1965, Ser. No. 453fi25 8 Claims. (Cl. 148-443) ABSTRACT OF THE DISCLGSURE A method and apparatus for quenching metal which is adaptable for use in a continuous process. The apparatus comprises two plate members spaced from each other having an aligned passageway therewithin for the passage of work through the plates. The plates are disposed substantially perpendicular to the line of travel of the work and gas is propelled against the surface of the first plate member surrounding the passageway, and liquid coolant is propelled against the surface of the second plate member surrounding the passageway. As a result, a. substantially planar mass of gas and a substantially planar mass of liquid coolant are provided across the passageways of the first and second plate members.

This invention relates to quenching, is. rapid cooling or metal after application of some thermal treatment. More particularly, the invention relates to method and apparatus for quenching which is adaptable in continuous processing systems.

To develop and improve physical and metallurgical properties, various thermal or heat treatments have been devised. In many heat treatments, it is important to rapid- -1y lower the temperature of the metal workpiece after heating to elevated temperature to produce desired metallurgical structure and corresponding physical properties. Many quenching systems have been proposed and used to accomplish rapid temperature reduction from elevated temperature. Among these systems are the relatively simple technique of immersing the metal workpiece in a coolant and more complex methods such as those involving the use of sprays and mist.

In many metallurgical practices, it is desirable to initiate quenching of a metal workpiece abruptly and with minimum premature cooling. Thus, the metal should be quenched as soon as possible after leaving the heat treating furnace. To this end, continuous heat treating systems have been designed with quenching systems adjacent the heat treating furnaces with the aim of cooling the metal workpiece as quickly as possible as it emerges from the furnace. In continuous systems, it is necessary that each successive increment of workpiece, as it moves through the quench, be contacted with coolant about its entire periphery at the same instant to insure straightness and uniform properties of the quenched product. Among the more popular quenching procedures have been those which employ sprays from nozzles strategically located to accomplish the maximum cooling of the metal workpiece. Such spraying techniques, however, sutfer from the disadvantage that a good deal of splashing occurs which may cause premature cooling of the portion of the workpiece not yet within the quenching zone and back up of coolant into the furnace. To minimize premature cooling and back up of coolant, a spray of gas, e.g. air, directed at a workpiece behind the coolant, has been used in an attempt to control coolant flow. Typically, quenching systems employ a plurality of nozzles aimed in a predetermined fashion to provide optimum cooling of a workpiece under static conditions. This approach further suffers from the obvious drawback that disruption of the ideal conditions requires readjustment of the sprays for optimum quenching. Variations from the static conditions upon which designs are based occur frequently in continuous systems because the metal may vary slightly in size and shape and its path of travel can also change somewhat.

The present invention avoids the aforementioned problems and provides a method and apparatus for quenching metal which is adaptable for use in continuous processing systems without the necessity of constant readjustment. The quenching arrangement of the invention further provides a sharp quench line without disadvantageous premature cooling of the metal workpiece and without undesirable back up of coolant into the furnace. Because there is no danger of coolant back up into the furnace, the apparatus can be positioned immediately adjacent the exit of the heat treating furnace for optimum metallurgical perforamnce.

The quenching system of the invention can be regarded as including two quenching zones, although for light sections only the first of these may be sufiicient to accomplish the desired rapid temperature reduction. In the first quenching zone are positioned two plate members spaced from each other and having aligned passageways for passage through them of a metal workpiece emerging from the heat treating furnace. The plate members are positioned substantially perpendicular or normal to the line of travel of the metal workpiece. Against the first of the plate members located nearest the furnace is projected gas, e.g. air, around the passageway in the plate. In a similar manner, a liquid coolant is projected on the surface of the second plate also around the passageway. In this way, the substantially planar mass or curtain of gas and liquid coolant is projected across the passageway of each of the plate members through which metal from the heat treating furnace is passed. The velocity and volume of the gas projected against the first plate is controlled so that it is sufficient to prevent liquid coolant which would otherwise flow or splash backward after impinging on the metal workpiece from doing so. As a consequence, a substantially fine quench line results around the periphery of the traveling metal workpiece which, if an elongated section, is progressively cooled in increments by passage through a curtain of liquid coolant. A particular advantage of normal to-the-work coolant impingement provided by the coolant plate is that departures from the nominal pass line and of nominal workpiece dimensions will not disturb the simultaneity of quench around the periphery of the workpiece (as would be the case with conventional angled-spray quench arangements). Another important advantage of this system is that individual positioning and adjustment of a large number of nozzles is avoided. Thus, it is apparent that my invention has the advantage of requiring no fine adjustments of nozzles for quenching and can tolerate considerable deviation in shape and path of travel of the metal workpiece.

As desired and according to the preferred embodiment of the invention, a second quenching zone can be positioned immediately adjacent the first quench zone, to accomplish further reduction in temperature of the interior of the metal workpiece. This latter arrangement is particularly advantageous when treating relatively thick sections of metal such as steel in which the first quenching zone can be effectively employed to accomplish a rapid reduction of the surface temperature and the second quenching zone can be used to lower the interior temperature of the metal workpiece to the desired level while maintaining the low surface temperature obtained in the first quenching zone.

Where straightness of the product is important, the metal workpiece is restrained during quenching to minimize or preclude distortion during the drastic temperature La reduction which occurs on quenching. In the processing of steel structural shapes, to which the invention is especially well suited, the restraint must be considerable and is best accomplished with groups of four rolls arranged in pairs, horizontally and vertically around the steel beam to confine it. Many such groups of rolls will be used for long beams and some may be located within the second quenching zone.

Other aspects and advantages of the invention will be more evident by the following description taken together with the drawings wherein:

FIGURE 1 is a schematic side elevation partly in section of a preferred embodiment of the quenching apparatus;

FiGURE 2 is a section taken along lines lIIi of FIG- URE 1 showing the gas-curtain portion of the first quenching zone;

FIGURE 3 is a section taken along lines TIL-III of FIGURE 1 showing the liquid coolant portion of the first quenching zone;

FIGURE 4 is a vertical cross section taken along lines IVIV of FIGURE 2; and

FIGURE 5 is a sectional view taken along lines VV of FIGURE 1 through the second quenching zone.

As is seen in FIGURE 1, a metal workpiece 8 passes through the quenching apparatus as it emerges from the heat treating furnace 1h. The metal workpiece 8 is advantageously restrained during quenching by horizontal and vertical rolls positioned throughout the quenching apparatus. It is necessary to restrain the metal workpiece during the rapid temperature reduction to obtain maximum straightness. The first set of rolls illustrated include horizontal rolls 14a and 14b and vertical rolls 16a. The first quenching zone comprises the aforementioned combination of spaced apart gas and liquid coolant curtains arranged so as to provide a substantially planar mass of gas and a substantailly planar mass of liquid coolant across the passageways in each of the plate iembers 2% and 30, respectively. The first plate member 28 is secured to and spaced from second plate member 36} by means of bolts 26 and sleeves 26. The plates are spaced apart in such a manner as to permit the gas to escape with minimum turbulence. Plate member 30 is in turn secured to a frame or housing 29 by quick disconnect fasteners 28. Quick disconnect couplings 23a and 23b permit the gas and coolant lines, respectively, to also be rapidly disconnected. Each of the

plate members

20 and 30 contains a passageway for the metal workpiece which preferably conforms to the configuration of the workpiece. In the embodiment illustrated, the workpiece is shown as a steel I-beam; however, it is apparent that other cross sections can be similarly treated and when other shapes are proc cssed,

plate members

20 and 30 can be replaced with other plates having passageways generally conforming to the shape to be processed. To facilitate rapid replacement of the quenching plates, the aforementioned quick disconnect fasteners 28 are employed and both

plate members

20 and 3%) can be removed as a unit with a similar unit having appropriately shaped passageways quickly substituted therefor.

As is best seen in FIGURES l and 2, air is supplied to plate member 20 by nozzles 24a, 24b, 24c and 2412' which are distributed around the passageway and which direct gas against the plate surrounding or circumscribing the passageway 41 Gas is supplied to the nozzles by manifolds 22a, 22b, 22c and 22b. Connected to each of the manifolds but shown for simplicity as connected to only one thereof, is a fluid line 21 which receives gas from a suitable supply such as a compressor (not shown). A pressure regulator 23 may be advantageously included along with valve 25 and flow meter 27 to insure a measured and controlled supply of gas to each of the manifolds.

The second plate member 3t? supports the first plate member 20 to which it is fastened and is in turn supported on a frame 29 by quick disconnect couplings 28.

As best seen in FIGURES l and 3, liquid coolant is supplied against the surface of plate member 39 by a plurality of nozzles positioned to surround the passageway d2. Nozzles 34a, 34c and 34b receive liquid coolant from

headers

32a, 32b, 32c and 32b respectively. Each of the headers is preferably connected to an independent coolant supply but for simplicity only one such line is shown in the drawings. As can be seen, liquid coolant is supplied through line 31 from a suitable supply or reservoir by a pump 33. A pressure regulator 35, a control valve 37' and a flow meter 39 may be advantageously used to furnish a measured and controlled supply of liquid coolant to each of the headers.

The second quenching zone is located adjacent the first quenching zone and may comprise any suitable means for delivering coolant to the workpiece in sufiicient quantity to lower the interior temperature of the metal workpiece to the desired level while maintaining the surface temperature at substantially that obtained in the first quenching zone. In the embodiment shown, the second quenching zone comprises a suitable housing within which is disposed a plurality of horizontal restraining rolls 54a, 54b, 56a, 56/], 58a and 58b which coact with a plurality of vertical restraining rolls 54c, 56c and 58c. The horizontal and vertical rolls are present in pairs on opposite sides of the metal workpiece, as best shown in FIGURE 5. Within housing 5t} are disposed a plurality of conventional spray nozzles and coolant supply headers 52a, 52b, 52c, 5261, 52c, 52], 52x, 52y and 522. Each of the headers in the second quenching zone is supplied with liquid coolant in a conventional manner. Since the function of this quenching zone is simply to withdraw heat from the interior of the metal workpiece as rapidly as possible, it is only necessary to supply coolant in suflicient quantity to extract heat from the metal workpiece as quickly as possible. A drain 57 may be provided for convenience, The requirements for the second quenching Zone are less rigorous than those of the first quenching zone. In the second zone, it is only necessary to keep the entire surface of the work continuously wet with coolant to insure constant heat removal from the interior of the workpiece.

The manner in which the combined plate members in the first quenching zone function to provide a fine quenching line around the periphery of the metal is best seen in FIGURE 4. The passageways in

plate members

20 and 30 are preferably beveled as shown to assist in providing a thin line of contact of the gas and liquid coolant onto the metal workpiece. Gas supplied against the surface of plate member 20 surrounding the passageway 40, which conforms generally to the configuration of the metal workpiece 8, is supplied in sufficient volume and velocity to effectively retard and prevent back flow of liquid coolant after impingement against the metal workpiece 8. This gas flow 44- is shown diagrammatically and extends substantially to plate member 36. If splashing of the coolant was not restricted, the total flow of coolant on the workpiece would be divided so that half would flow forward on the workpiece and half flow backward toward the furnace. Back flow must, of course, be avoided to prevent injury to furnace operation as well as to minimize premature cooling of the workpiece.

Where .straightness of the product is a significant factor, it is, as has been described above, advantageous to restrain the metal workpiece during quenching. A suitable arrangement for this purpose is the combination of horizontal and vertical rolls described above. The arrangement of the rolls in this fashion is best shown in FIGURE 5 which shows one such assembly in the second quench zone. As can be seen, horizontal rolls 54a and 54b coact with vertical rolls 54c and 54a to confine the metal workpiece 8. FIGURE 5 also shows typical dispositions of sprays 5212, 52y, 52c and 52y surrounding the workpiece within the second quenching zone. The groups of restraining rolls which may also be used to convey as well as support the work should be as closely coupled as possible, consistent with operating and maintenance requirements. To facilitate a compact arrangement, the roll groups may be supported by housings (not shown) common to all rather than by individual housings. The rolls may also be either individually driven or driven from a common drive, and the roll spacing should be adjustable to accommodate a variety of work. An integrated control system may be provided to insure that all roll drives are speed matched and either electric motor or fluid power drives may be used.

As an example of the operation of the invention, a 16-inch, wide-flange beam Weighing 78 lb./ft. moving through the furnace at 3.75 f.p.m. can be quenched from a temperature of about 1800" F. to about 300 F. with a total water flow of about 460 g.-p.m. divided so that about half is supplied in each of the two quenching zones. Where, as in the preferred embodiment, a low nozzle pressure, eg 25 psi, is used to encourage laminar flow, 30 nozzles or outlets of Ar-inch inside diameter distributed so as to discharge coolant around the passageway can be employed in the first quenching zone. This can be accomplished with ten outlets on about 2-inch centers directing coolant toward each flange (20 coolant outlets total) and 5 outlet on about 3-inch centers directing coolant toward each side of the web' To prevent back flow of water, air is supplied to the first plate ahead of the water plate through 30 -inch nozzles each delivering 4 c. f.m. of air at 60 psi. The air nozzles are similarly positioned around the passageway. While the requirements are less rigorous, coolant supplied in the second quench should be distributed over the length of the work within it so that maximum heat removal is achieved. The nozzles used in this zone will be able to project sprays onto the entire surface of the work to maintain substantially the same surface temperature achieved in the first quenching zone while cooling the interior to the desired low temperature.

It is apparent that various changes and modifications may be made without departing from the invention. Spacing between the plates in the first quenching zone may be varied to produce different effects as desired; however, with increased spacing the effectiveness of the gas curtain in preventing back fiow of liquid coolant is lessened. It is also desirable to minimize turbulence of gas and cooland between the plates, as this also reduces the effectiveness of the gas curtain. As might be expected, the quantity of gas required to prevent back flow of coolant increases as the coolant flow is increased. However, optimum adjustments can be readily arrived at for specific equipment. It is also obvious that relatively simple cross sections such as slabs or plate may be proceed as well a structural shapes and beams.

I claim:

1. An apparatus for quenching metal adaptable for use in a continuous processing system comprising first and second plate members spaced from each other and having aligned passageways therein for passage of metal therethrough, said plate members being disposed substantially perpendicular to the line of travel of said metal, means to propel gas against the surface of said first plate member surrounding the passageway therein and means to propel liquid coolant against the surface of said second plate member surrounding the passageway therein, whereby a substantially planar mass of gas and a substantially planar mass of liquid coolant are provided across the passageways of said first and second plate members, respectively.

2. An apparatus for quenching metal adaptable for use in a continuous processing system comprising first and second quenching zones, said first quenching zone comprising first and second plate members spaced from each other and having aligned passageways therein for passage of metal therethrough, said plate members being disposed substantially perpendicular to the line of travel of said metal, means to propel gas against the surface of said first plate member surrounding the passageway therein and means to propel liquid coolant against the surface of said second plate member surrounding the passageway therein, whereby a substantially planar mass of gas and a substantially planar mass of liquid coolant are provided across the passageways of said first and second plate members, respectively; said second quenching zone being positioned adjacent to said first quenching zone and adapted to receive metal therefrom, said second quenching zone comprising means to deliver coolant into contact with said metal to extract heat therefrom.

3. An apparatus for quenching metal adaptable for use in a continuous processing system comprising first and second quenching zones and means to restrain said metal to substantially prevent distortion thereof during quenching, said first quenching zone comprising first and second plate members spaced from each other and having aligned passageways therein for passage of metal therethrough, said plate members being disposed substantially perpendicular to the line of travel of said metal, means to propel gas against the surface of said first plate member surrounding the passageway therein and means to propel liquid coolant against the surface of said second plate member surrounding the passageway therein, whereby a substantially planar mass of gas and a substantially planar mass of liquid coolant are provided across the passageways of said first and second plate members, respectively; said second quenching zone being positioned adjacent to said first quenching zone and adapted to receive metal therefrom, said second quenching zone comprising means to deliver coolant into contact with said metal to extract heat therefrom.

4. An apparatus for quenching metal adapt-able for use in a continuous processing system comprising first and second quenching zones and means to restrain said metal to substantially prevent distortion thereof during quenching, said first quenching zone comprising first and second plate members spaced from each other and having aligned passageways therein for passage of metal therethrough, said plate members being disposed substantially perpendicular to the line of travel of said metal, means to propel gas against the surface of said first plate member surrounding the passageway therein and means to propel liquid coolant against the surface of said second plate member surrounding the passageway therein, whereby a substantially planar mass of gas and a substantially planar mass of liquid coolant are provided across the passageways of said first and second plate members, respectively; said second quenching zone being positioned adjacent to said first quenching zone and adapted to receive metal therefrom, said second quenching zone comprising means to deliver coolant into contact with said metal to extract heat therefrom; said means to restrain said metal during quenching being disposed ahead of said first quenching zone and within said second quenching zone.

5. An apparatus according to claim 4 wherein said means to restrain said metal during quenching comprises groups of rolls and each group of rolls comprises a pair of horizontally disposed rolls and a pair of vertically disposed rolls, said horizontally disposed rolls being adapted to contact the top and bottom of said metal and said vertically disposed rolls being adapted to contact opposite sides of said metal.

6. In a process of heat treating metal wherein said metal is quenched after passing through a heat treating furnace, the improvement comprising passing said metal as it comes out of said furnace through a quenching zone comprising a plane of high velocity gas and a plane of coolant, both of which are substantially perpendicular to the line of travel of said metal, the velocity and volume of said gas being suflicient to substantially prevent said coolant from flowing in a direction opposite to the direction of travel of said metal after impingement upon said metal.

7. A method of quenching metal as it emerges from a heat treating furnace comprising passing said metal through a first quenching zone to rapidly lower the surface temperature of said metal and then passing said metal through a second quenching zone to lower the internal temperature of said metal, the temperature of the surface of said metal being rapidly reduced in said first quenching zone 'by passing said metal through a plane of high velocity gas and a plane of liquid coolant, both of which are substantially perpendicular to the line of travel of said metal, the velocity and volume of said gas being suflicient to substantially prevent said liquid coolant from flowing in a direction opposite to the direction of travel of said metal after impingement upon said metal.

8. A method of quenching metal as it emerges from a heat treating furnace comprising passing said metal through :a first quenching zone to rapidly lower the surface temperature of said metal and then passing said metal through a second quenching zone to lower the internal "temperature of said metal and restraining said metal while passing same through said first and second quenching zones to substantially prevent distortion thereof, the temperature of the surface of said metal being rapidly reduced in said first quenching zone by passing said metal through a plane of high velocity gas and a plane of liquid coolant, both of which are substantially perpendicular to the line of travel of said metal, the velocity and volume of said gas being suflicient to substantially prevent said liquid coolant from flowing in a direction opposite to the direction of travel of said metal after impingement upon said metal.

References Cited UNITED STATES PAT ENTS 3,036,825 5/1962 Eisenrnenger 2664 3,148,093 9/1964 Williams et a1. 148-445 X 3,208.7 9/ 1965 Peretick 266-4 FOREIGN PATENTS 870,556 6/1961 Great Britain.

CHARLES N. LOVELL, Primary Examiner.