US3604696A

US3604696A - Continuous quench apparatus

Info

Publication number: US3604696A
Application number: US782522A
Authority: US
Inventors: Vincent R Coleman; Perry J Murphy Jr; Victor N Lockhart
Original assignee: Van Dorn Co
Current assignee: Van Dorn Co
Priority date: 1968-12-10
Filing date: 1968-12-10
Publication date: 1971-09-14
Anticipated expiration: 1988-09-14
Also published as: FR2025731A1; DE1946025A1; GB1239165A

Abstract

Apparatus for continuously and progressively quenching elongated flat steel members comprising a plurality of pairs of continuous cylindrical rolls, each roll pair being closely spaced from a successive roll pair and comprising an upper roll aligned and parallel with a lower roll, the nips of the roll pairs lying in the same plane. A plurality of upper and lower jet quench means are positioned between successive rolls, above and below said plane, the apparatus including means to support the rolls so that they apply a pressure on the steel member being quenched along continuous lines of contact across the member. Passageway means are provided in the rolls for a cooling fluid to cool the rolls, the rolls thereby providing an additional cooling action along said lines of contact of the rolls with the member so that the quenching is uninterrupted, uniform and complete.

Description

United States Patent [72] Inventors Vincent R. Coleman Aurora, Ohio; Perry J. Murphy, Jr., Pittsburgh; Victor N. Lockhart, lrwin, Pa. [21] Appl. No. 782,522 [22] Filed Dec. 10, 1968 [45] Patented Sept. 14,1971 [73] Assignee The Van Dorn Company Cleveland, Ohio [54] CONTINUOUS QUENCl-l APPARATUS 3 Claims, 11 Drawing Figs.

{52] US. Cl 266/6 S, 72/201 [51] lnt.Cl C2ld H62 [50] Field of Search 266/3, 6, 6 S; 72/201 [56] References Cited UNITED STATES PATENTS 3,367,804 2/1968 Teplitz 266/6 2,056,433 10/1936 Matthews 72/201 Primary Examiner-Gerald A. Dost Attorney-Meyer, Tilberry and Body ABSTRACT: Apparatus for continuously and progressively quenching elongated flat steel members comprising a plurality of pairs of continuous cylindrical rolls, each roll pair being closely spaced from a successive roll pair and comprising an upper roll aligned and parallel with a lower roll, the nips of the roll pairs lying in the same plane. A plurality of upper and lower jet quench means are positioned between successive rolls, above and below said plane, the apparatus including means to support the rolls so that they apply a pressure on the steel member being quenched along continuous lines of contact across the member. Passageway means are provided in the rolls for a cooling fluid to cool the rolls, the rolls thereby providing an additional cooling action along said lines of contact of the rolls with the member so that the quenching is uninterrupted, uniform and complete.

h .55 a i 9 i u vi8 I I z T as fi -16 '34 PATENTED SEP1 4197i SHEET 1 0F 5 FlG.l

i x 'mons. 113

VINCENT R LEMAN PERRY J M 9w, JRfa gg cToa N. LOCK-HART Me afllw 8; B

A TORNE 3 FIG. 2

PATENTED SEP 1 4 1971 SHEET 3 OF S Fl (5. 9A

INVENTORS. R. COLEMAN,

MURPHY JR. a VICTOR N. LOCKHART 1% m a M,

ATTORNEYS CENT ERRY J.

PATENTED SEP 1 4 I87! 3 604 696 SHEET 5 OF 5 1! (I) 9 LI.

lfiamoas. VINCENT R. co smm. PERRY J MU Y.

VICTOR N10 riHART BY M8,. 214 a Bad;

ATTORNEYS CONTINUOUS QUENCH APPARATUS The present invention relates to the art of quenching elongated flat steel members, such as steel strip or steel sheet members, and particularly to apparatus for continuously and progressively quenching said steel members.

The invention is particularly directed to a quench system for use with lower carbon alloy steels where the rate of quench must be very high and where variations in the quench rate between various portions of the member produce variations in the physical characteristics of various portions of the quench member, and 'will be described with particular thereto, although it will be appreciated that the invention has broader applications such as the quench of high or low alloy steel members of any thickness.

It is known that the physical characteristics of a carbon steel member, e.g. hardness, tensile strength and ductility can be improved by heating the member above its austenizing temperature and then rapidly cooling or quenching the member to below its Ms temperature. lt is also known that as the alloy content of steel is lowered, the quench rate must be very high if the desired improvements in the physical characteristics are to be obtained. Thus with such lower alloy steels, the quench rate is critical and small variations in the temperature in the various portions of the member at the beginning of quench, or small variations in the rate of quench on various portions, will produce large variations in the physical characteristics of the quenched member.

A further problem with quenching large steel members having flat surfaces is that the members tend to warp or bow as a result of the quenching process, which can be prevented only by rigidly supporting or clamping all portions of the member during the quenching operation.

it is known to quench steel plate or other types of members in what is termed a batch-platen quench unit. In this unit, the hot plate is moved from a furnace into an adjacent quenching fixture where it is gripped between rigid upper and lower platens, securely holding the plate, each having a large number of feet in'a wafflelike pattern which contact the upper and lower surfaces of the plate. A plurality of sprays or jets direct large volumes of water onto both the upper and lower surfaces of the plate. During the quench operation, the platens rigidly hold the plate to prevent it from warping, bowing or bulging. Upon completion of quench, the platens are released and the plate is then transported to a tempering furnace.

A serious disadvantage with the batch-platen quench system is that there is an appreciable amount of time required to move the plate from the furnace into the quench fixture. This time is sufficient, particularly with thin gauge, low hardenability steels where the heat loss can be relatively rapid, for the temperature of the plate to drop a significant amount losing some of the value of a rapid quench from a high temperature.

in addition the leading edge or portion of the plate will be out of the heating furnace and exposed to room temperature for a longer period of time than the trailing edge, or portion, before quench is commenced. This means that prior to the start of quench, the leading edge of the plate which has been out of the furnace the longest period of time will have cooled to a lower temperature than the trailing edge of the plate which has been out'of the furnace for a shorter period of time. When the whole plate is quenched simultaneously, to a much lower temperature, the rate of cooling will vary throughout the plate, in turn resulting in a plate of nonuniform hardness and strength.

Another serious disadvantage with the batch-platen quench system is that pockets of steam are likely to form on the surfaces of the plate being quenched. These steam pockets have a low heat conductance, and tend to blanket areas of the plate, varying the rate of 'heat removal across the plate resulting in nonuniform hardening of the plate.

In addition, because the batch-platen system requires continuous holding contact between the feet of the platens and the plate at spaced points during the quench operation, the

feet will mask-off portions of surface areas of the plate from the quench water, also varying the rate of heat removal from the plate, resulting in nonuniform hardening and possibly the development of soft spots at these areas of contact.

As a further problem, quenching causes substantial transformation and thermal volume changes, and a rigid restraint on the plate by the platen feet opposing the dimensional changes can cause serious surface scratch marks on the plate, and localized areas of fatigue or stress concentration. Also, it is difficult to uniformly distribute the quench water over the top and bottom surfaces of the plate in the conventional batch-platen system resulting in nonuniform hardening.

It is known to quench steel plate in a continuous manner in what is called a roller quench unit. This unit consists of upper and lower roller assemblies arranged so that the plate passes between the upper and lower rolls. Between each set of rolls, the plate is subjected to upper and lower sprays of quench water, so that the plate is progressively cooled as it proceeds through the unit. In order to prevent the rolls from masking substantial areas of the steel plate from the quench water, each roll is made up of a series of spaced-apart washerlike discs which contact the plate progressively along a longitudinal line, the effect being similar to the wafflelike pattern of the batch-platen system. Although this roller quench unit has the advantage over the batch-platen system that quench of the plate is carried out, in a lengthwise direction, from the same high temperature, the unit still is little more than an extension of the batch-platen system in that there are contact points between the rolls and plate being quenched where the surface of the plate is masked from the cooling spray water. Even though the areas masked by the rolls are made as small as possible, an uneven rate of cooling can occur and soft spots or lines along the plate can result.

Even more serious, steam pockets form upon the surfaces of the plate during the quench period. As with the batch-platen system, these steam pockets have a low heat conductance, and blanket areas of the plate, resulting in uneven cooling across the plate and nonuniform hardening.

it is an object of the present invention to overcome the above disadvantages, and in particular to provide a continuous, uninterrupted and progressive quench system which achieves a uniform rate of cooling across the member being quenched.

In accordance with the present invention, there is provided a quench unit for continuously and progressively quenching elongated flat steel members comprising a plurality of pairs of continuous cylindrical rolls (as distinguished from the spaced washers of the prior art), each roll pair being closely spaced from a successive roll pair and comprising a cylindrical upper roll aligned and parallel with a lower roll; the nips between the roll pairs lying in the same plane; a plurality of upper and lower jet quench means positioned between successive rolls above and below said plane adapted to introduce a quenchant onto the upper and lower surfaces of a member being quenched; support means spacing said rolls in a close spacedapart relationship so that the rolls exert a continuous pressure on the member along continuous lines of contact across the width of the member, the rolls thereby squeezing out any steam pockets which have commenced to form on the surfaces of the member; the rolls also being hollow and internally cooled by a suitable cooling medium to provide an additional cooling action along said lines of contact so that the quench is uninterrupted, uniform and complete. The rolls are preferably of the same diameter and are all driven at exactly the same speed so that the member as it cools and shrinks is subjected to tension forces between adjacent pairs of rolls which hinder warpage in a longitudinal direction, and of course rigidly hold the member in a transverse direction to hinder warpage in tha direction.

In accordance with an additional phase of the invention, backup rolls are provided which are cylindrical and coextensive with the pressure rolls, in contact with successive pairs of pressure rolls. The backup rolls are hollow and cooled to extract heat from the surfaces of the pressure rolls.

In a further additional phase of the invention, each pressure roll is in contact with a plurality of axially aligned and axially spaced backup roll segments with each roll segment being individually adjustable so as to permit the application of different pressures on different axial portions of the pressure rolls to cause the latter to exert different pressures on the member being cooled across its width. The frictional engagement of the pressure rolls with the member thus differs at various points across the width thereof, permitting the quench unit of the invention to be used for leveling the member being quenched, with different compensating tension forces across the width of the member.

In a further aspect of the invention, the quenchant adjacent the inlet end of the quench unit will be in the form of highpressure high-velocity jets designed to cause an immediate uniform surface quench across the width of the plate and at the same time inhibit the formation of steam pockets, and/or if they should form to flush them away from the surface; followed by medium pressure jets, and then a plurality of flooding jets towards and up to the outlet end of the quench unit.

It will become apparent that the present invention offers a substantial advance in the art in providing not only an improved immediate quench by which every part of the member being quenched is cooled from the same high temperature, but in addition, a means by which the member is uniformly cooled at the same rate throughout. since the hardness and strength achieved is a function of cooling rate, this results in more uniform levels of hardness and strength in the member.

The invention and these and other advantages will become more apparent upon consideration of the following specification with reference to the accompanying drawings, in which FIG. 1 is a section elevation view of a quench unit in accordance with the present invention;

FIG. 2 is a schematic section elevation view of the unit of FIG. IiIIustrating the principles of the invention;

FIG. 3 is a plan view of the machine of FIG. 1;

FIG. 4 is a section view taken along line 4-4 of FIG. 2;

FIG. 5 is a detailed elevation view of a portion of the machine of FIG. 2 illustrating the concepts of the invention;

FIG. 6 is an enlarged detailed view of a spray nozzle in accordance with the concepts of the invention;

FIG. 7 is an enlarged detailed view of a further spray means in accordance with the invention;

FIGS. 8 and 8A are an elevation view and section view respectively illustrating an embodiment of the invention; and

FIGS. 9 and 9A are an elevation view and section view, respectively, illustrating schematically a further embodiment of the invention.

Referring to the drawings, particularly FIGS. 1 and 2, for the purposes of illustrating the preferred embodiment of the invention only and not for the purpose of limiting the same, the figures show a quench unit for continuously and progressively quenching elongated flat steel members, which comprise a plurality of successive upper and lower pairs of pressure rolls R,, R R R,..., which pairs are in spaced-apart relationship, and between which are successive quench zones 0,, Q Q 0 In each of the quench zones, there are positioned upper and lower jet quench means 1,, J J J positioned to force a suitable quenchant onto the upper and lower surfaces of a member M being cooled in the quench zones. The'rolls R are hollow and provided with a suitable coolant which is flowed through the rolls. In operation, the member M to be quenched is introduced into one end of the quench unit (in this view, the left end), and is passed through the unit at a relatively high rate of speed, between the nips of the pairs of pressure rolls R, exiting at the opposite or right end.

Particulars of the invention will now be described.

In FIG. I, the quench unit comprises a suitable frame 12 having an upper framework 14 which supports the upper pressure rolls R,, R R,..., and a lower frame work 16 which supports the lower pressure rolls R R R The pressure rolls are supported in suitable upper and lower bearing chocks 18 and 20, respectively, at opposite ends of each of the pressure rolls. As shown, the rolls are arranged in pairs, each pair comprising an upper roll and a lower roll which are spaced close together and are parallel, successive rolls pairs being spaced apart and also parallel. The roll pairs are arranged so that the nips of each of the roll pairs lie in the same plane, preferably in a horizontal plane, and so that the member being quenched passes in that plane through the quench unit.

Generally the quench unit frameworks can be open along the sides and ends thereof, except for the members which support the rolls. the bearing chocks for the lower pressure rolls may be rigidly mounted within the lower framework 16, whereas the upper pressure rolls are mounted in slides 22 which support the chocks for the upper rolls and which move up and down in guideways 24, the latter being part'of the upper framework 14. On opposite sides of the quench unit, flanges 26, also part of the upper framework 14 above the upper pressure rolls, provide seats for a plurality of springs 28, the springs bearing against the lower surface of the flanges causing the slides 22 to force the upper pressure rolls against the member being quenched. The spring forces are made adjustable, for instance by nuts 30 precompressing the springs, to vary the force of the rolls against the member being quenched.

In accordance with the invention, all of the rolls are driven at the same peripheral speed so that the member being quenched as it cools and shrinks is subjected to tension forces between adjacent pairs of rolls. This may be accomplished in a number of different ways, but in the embodiment shown the lower rolls R R R are driven through a plurality of drive sprockets 32, one connected to each lower roll, by a plurality of continuous chains 34. A second chain 36 is connected between a lower sprocket 38 and a speed reducer 40, driven by motor 42 at variable speeds. Driving the lower rolls causes the member being quenched to advance from one end of the quench unit to the other, the upper rolls being idler rolls.

FIGS. 2-4 illustrate the jet quench means in accordance with the invention showing a plurality of jet means j,, J J J positioned in each of the quench zones 0,, Q Q 0,..., between successive roll pairs, the jet means J,, J J being above the member to be quenched, those labeled J J .l ...being below the member. Each of the jet means comprises a laterally disposed coolant pipe 50 which is centered between and parallel with the pressure rolls, the pipes lying in horizontal planes spaced equidistant from the member being quenched, at about a distance equal to the diameter of the pressure rolls. The coolant pipes are supplied with a suitable quenchant, which may be a liquid or gas, by manifold pipes 52 which extend above and below the coolant pipes longitudinally along the axis of the quench unit centered between the opposing sides of the unit. Connections 54 between the manifold pipes 52 and coolant pipes 50 distribute the quenchant to the coolant pipes.

The quenchant is distributed by each of the coolant pipes uniformly across the surface of the member being quenched rapidly cooling the member. In an embodiment of the invention, there will be over the length of the quench unit a first high pressure quench entering zone 0,, Q adjacent the inlet end of the unit and between the first and second pairs of rolls; followed by an intermediate high pressure zone 0 0,, between the second and third pairs of rolls; and a subsequent low pressure flooding zone Q Q extending from the intermediate zone to the quench unit outlet end.

FIG. 4 illustrates the jet pattern of the first set of jets in the entering high pressure quench zone 0,, O in this example between the first and second pairs of pressure rolls. As shown, the upper coolant pipe .I is provided with downwardly oriented apertures or nozzles 56 (illustrated in detail in FIG. 6) and the lower coolant pipe J is similar in design provided with upwardly oriented apertures or nozzles. Although the design of the particular jet aperture or nozzle used is not critical, the nozzle illustrated in FIG. 6 has proven to be operative. Spaced effectively laterally across the width of the quench unit, the nozzles 56 produce a plurality of high pressure, fan shaped jets which overlap and uniformly contact the member being quenched across its width as the latter is advanced into the quench unit.

In the following high pressure zone 0 0,, which in this example is the area between the second and third pressure roll pairs, the upper and lower coolant pipes are provided with medium pressure jet nozzles of slightly larger dimension on centers spaced slightly further apart, but having essentially the same design as the nozzles of FIG. 6, producing overlapping medium pressure fan jets. The difference is that in this zone a greater quantity or volume of quenchant at slightly lower pressure is caused to impinge on the member upper and lower surfaces than in the entering zone 0,, Q

In the low pressure flooding zone 0,, 0 which constitutes the remaining extent of the unit, the upper and lower coolant pipes are provided with slots 58, as shown in FIG. 7, which run longitudinally along the pipe, or laterally with respect to the quench unit. The slots have a much increased cross-sectional area, over the area provided by the nozzles of FIG. 6, to flood the surfaces of the member being quenched with a low pressure sheet or jet of the quenchant.

Although in the above example, the entering high pressure quench zone and intermediate pressure zone are shown as each comprised of only a single set of coolant pipes encompassed by only two pairs of pressure rolls, it is apparent that in a unit of much greater length having a greater number of pressure rolls, these zones will comprise a larger number of coolant pipes encompassed by a large number of the roll pairs. For instance, each of these two zones may comprise three or four pairs of rolls and an equivalent number of coolant pipes.

It is a significant feature of the invention, that, in addition to extracting heat from the member in the quench zones by means of jets of quenchant, the cooling of the member is continued along the lines of contact between the pressure rolls and the member, for the purpose of providing a continuous uninterrupted uniform rapid quench of the member. This is accomplished by internally cooling the pressure rolls.

The figures, particularly FIG. 3, show the manner in which the pressure rolls are internally cooled. Each pressure roll is hollow (as shown in FIG. 2) and connected to a suitable manifold arrangement 60 (FIG. 3) consisting of an inlet manifold pipe 62 having connections 64 leading to the inside of each of the pressure rolls through the bearing neck portions for the rolls. The flow may exit from the inside of the rolls through a suitable outlet line, for instance, one not shown positioned at the opposite end of each roll; or a collecting pipe 66 exiting through the neck along with the connection 64 leading to an outletmanifold 68.

The latter arrangement may be preferred in that it does not interfere with the drive assembly for the lower rolls.

Although the pressure rolls are shown as being hollow, as an alternative, they may be more solid and provided with a plurality of longitudinally extending passageways for the flow of coolant.

In the example of the unit shown in FIGS. l-5, the rolls are about 7% inches in diameter constructed of SAE 1020 steel tubing having a wall thickness of about one-half inch. Obviously this diameter and wall thickness may vary, but the diameter should besufficiently small so that the rolls can be placed on closely spaced centers, but sufficiently large for strength requirements and to permit cooling of the roll surfaces between periods of contact with the hot plate; that is, as a particular portion of the roll surface is rotated out of contact with the member'being quenched, the diameter of the roll should be sufficientfor enough time to elapse for that portion to cool prior to recontact with the member. The surface of a small diameter roll may be out of contact with the member too short a time to appreciably cool and provide an appreciable quenching action. In the unit shown in FIGS. 1-5 the diameter of 7% inches has proven to be effective in meeting all criteria.

The pressure rolls extract an appreciable amount of heat, and an indication of the amount of heat extracted is the variation in roll surface temperature before and after contact with the member being quenched as well as the increase in the temperature of the coolant passed through the rolls. It can be appreciated that the roll surface temperature is a difficult variable to measure, but it is estimated that the temperature, as an indication of the amount of heat extracted by the rolls, will vary appreciably.

Any suitable coolant can be used to cool the rolls, for instance water, or gases, as long as the rolls are sufficiently cooled.

In operation, the member being cooled is introduced into the quench unit at a predetermined feed rate, dependent upon the temperature of the member, its thickness, composition and other factors, and the spacing between the quench unit and the heating furnace would be such that cooling of the leading edge of the member would commence almost immediately, the first cooling being by contact of the first pair of pressure rolls R,, R with the member. One advantage in this sequence of quench is that the pressure rolls prevent splashing of quenchant onto the member to be quenched in an indiscriminate manner, in turn preventing nonuniform cooling which would result.

In the subsequent high pressure quench zone Q,, Q between the first and second pairs of pressure rolls, the high pressure jet nozzles provide upper and lower high velocity jets of quenchant impinging against the upper and lower surfaces of the member. The velocity and fineness of the jets are such as to prevent, to a large extent, the formation of steam pockets on the surfaces of the member.

As the member is advanced in the quench unit at a relatively rapid rate of speed, any steam pockets which commence to form are quickly squeezed out by pressure contact of the roll pairs with the member, as shown in FIG. 5, the rolls being on closely spaced centers for this purpose. Since the rolls are cylindrical, the squeezing action of the rolls is continuous across the width of the member being quenched.

The next quenching action is by the second pair of quench rolls, further extracting heat from the member being cooled, all portions of the surfaces of the rolls being in a cooled state prior to contact with the member by virtue of the thin walls of the rolls and the fast moving internal coolant within the rolls. Subsequently, the member is again contacted with quenchant. this sequence repeating until the member is cooled. Also, by passing the steel member through the quench unit at a relatively high rate of speed, the quenching step is uninterrupted.

It should be noted that in the intermediate pressure zone 0 0 the temperature of the member being quenched has been lowered to the point where a greater amount of quenchant can be introduced onto the surfaces of the member, at lower pressure, the higher volume flow continuing the high rate of heat removal from the member. However, the quenchant is still in troduced onto the member through nozzles in a jetlike manner, and squeezing of forming steam pockets on the member is still an important function of the successive pairs of pressure rolls.

After cooling has progressed further to a sufficient degree, then the plate is flooded in the final cooling low pressure flooding zone by means of the coolant pipes provided with longitudinally extending slot nozzles. The length of this final zone, and the number of pairs of pressure rolls encompassing the zone depends upon a number of conditions, but in effect, its length is sufficient to remove the balance of the heat remaining in the member being quenched. In this final cooling zone, as throughout the length of the quench unit, the squeezing action of the closely spaced cylindrical rolls on steam pockets which have commenced to form continues to be important. Also the quenching action of the pressure rolls remains an important function of the rolls so that the cooling is continuous and uninterrupted. With respect to both functions, successive pairs of pressure rolls should be on closely spaced centers.

It is a feature of the invention that the high pressure jets, particularlyv in the first quench zone 0,, Q of the quench unit will remove at least in part scale which has formed on the surfaces of the member being quenched.

Advantages of the invention should now be apparent.

Since the successive pairs of pressure rolls are on closely spaced centers, and are able to prevent the formation of steam pockets on surfaces of the rapidly advancing member being quenched, the blanketing action of steam pockets is avoided and the rate of cooling of all portions of the member, not only across its width, but in a lengthwise direction is completely uniform. Since the rate of cooling is critical to hardness and strength, this results in complete uniform hardening and strengthening of the member.

In addition, by cooling the pressure rolls, the rolls extract heat from the member being quenched along the lines of contact between the member and the rolls continuing and contributing to the quenching step. In this way, there is no blanketing of the member, such as occurs with the platens or disctype rollers of the prior art, and cooling of all parts of the member is uninterrupted and maintained at a constant rate, for uniform hardening and strengthening of the member.

With respect to both functions of the pressure rolls, successive rolls should be as closely spaced as possible, in the order of about two inches, or a fourth of the roll diameters.

Additional advantages of the present invention, particularly over the conventional batch-platen quench system, should also be apparent. Since quenching is commenced almost immediately as the member being quenched leaves the furnace, and since the time lag prior to quenching is the same for every part of the member, the cooling or quenching of all parts of the member starts from the same temperature. This means that the rate of cooling for all parts of the member will be the same, and again, since the rate of cooling is critical to the hardness and strengthening obtained, the hardness and strength of all portions of the member will be the same.

This advantage is particularly important in cooling thin gauge low hardenability steel plate which loses temperature rapidly when exposed to room temperature even for short time periods after leaving the furnace and prior to the commencement of the quenching action.

In an example in accordance with the invention, a five foot long plate 36 inches wide was subjected to hardness testing, with the finding that the hardness varied across the surface of the plate less than one point Rockwell. This is indicative of uniform and complete quenching.

As a further advantage, an operator of the present unit can adjust the pressure which the opposing rolls of the roll pairs exert on the member being quenched to obtain a desired amount of tension on the member, or resistance to shrinkage as the member cools. It is an important feature of the invention that the pressure rolls R,, R R R are all of the same diameter, and the drive assembly is such that the rolls are all driven at the same speed. In this way, the operator can effect a desired amount of stretching during the quench operation to obtain what is called leveling of the member. As the member cools and shrinks, it is subjected to tension forces between adjacent pairs of rolls which reduce warpage in a longitudinal direction, the cylindrical rolls also holding the member in a transverse direction reducing warpage in that direction. This is particularly useful in quenching plate material which may have wavy edges or may be buckled as it enters the furnace. The shrinkage under tension causes some stretching of the plate minimizing the length differences. Close spacing of suc- 1 cessive pressure rolls is also important towards obtaining optimum leveling.

As a further advantage of the present invention, the surface I may be as much or more than thirty feet in length having thirty or more pairs of pressure rolls. Quite obviously, the quench unit could be sized even larger.

The embodiment of FIGS. 8 and 8A illustrates a typical production quench system in accordance with the invention,

comprising a large'number of successive pairs of hollow pressure rolls R R R ,'R,, with upper and lower jet quench means 1., J J .l.,.'.., between each roll pair. In the example of FIGS. 8 and 8A, the first six to eight roll pairs are equally divided into the entering high pressure quench zone and intermediate medium pressure quench zone, the remaining extent of the machine constituting the low pressure flooding zone of the quench unit.

flGS. 8 and 8A also illustrate an embodiment or variation in accordance with the invention. In the figures, the upper and lower pressure rolls R R R R are backed up by a plurality of backup rolls 70, each backup roll being bridged between successive pressure rolls, on the bottom and top of the quench unit. The backup rolls are continuous and cylindrical in shape, applying a backup pressure across substantially the entire width of the pressure rolls, urged by the spring means 72. The advantage of this arrangement is that in addition to strengthening the support of the pressure rolls, the backup rolls are also hollow and suitably cooled by a fluid introduced through a manifold arrangement 74, FIG. 8A. Cooling the backup rolls more rapidly cools the pressure rolls, between periods of contact with the member being quenched, and enhances the quenching effect of the pressure rolls in the quench operation.

In the embodiment of H68. 9 and 9A, a plurality of short spaced-apart backup rolls are employed across the width of the quench unit, also bridging the gap between successive upper rolls and successive lower rolls. Each of these backup rolls is adjustable, by adjusting means 82, so that the pressure exerted by the backup rolls against the pressure rolls can be varied across the width of the latter and across the width of the unit. This permits an operator to vary the tension across the width of the unit exerted on the member being quenched and to achieve a laterally variable amount of stretching of the member during the quench operation. ln this way, leveling of the plate during quench can be accurately effected. For instance, in a wide plate, the longitudinal edge dimensions may be greater than the longitudinal dimension along the center of the plate, and the plate will have wavy edges; whereas if the reverse is the case, the center of the plate will tend to buckle, as in an oil can. By suitably varying the pressure applied across the width of the plate by the pressure rolls, the longitudinal edge and center dimensions can be equalized during the quench step.

Although reference has been made to upper and lower rolls and upper and lower surfaces of the member being quenched, it is apparent that the quench unit of the present invention can be oriented in a vertical or other plane, the terms upper and lower merely being indicative of a spatial relationship of component parts. a

The invention has been described with reference to specific embodiments, but other variations within the scope of the following claims will be apparent to those skilled in the art.

We claim:

1. A device for quenching an elongated flat strip comprising; a bottom roll set including a plurality of horizontally spaced rolls of substantially the same diameter, an upper roll set including a plurality of horizontally spaced rolls of substantially the same'diameter and of substantially the same diameter as said rolls in said bottom roll set, each said roll in said upper roll set being vertically aligned and parallel with a corresponding roll in said bottom roll set, drive means for driving each roll in one of said roll sets at substantially the same speed in a predetermined direction to move a strip in a predetermined direction through said bottom and upper roll sets, each roll in the other of said roll sets being nondriven and mounted for independent rotation, each said roll in the other of said roll sets being individually mounted for movement toward and away from a corresponding roll in said one roll set, biasing means for independently biasing each roll in said other roll set toward said rolls in said one roll set, and quenching means for quenching a strip moving through said roll sets, said quenching means including a first quench means for supplying quenchant at high pressure and low volume to quench a strip moving through said roll sets at a first relatively slow quench rate, said quenching means including a second quench means spaced from said first quench means in said predetermined direction of travel of a strip through said roll sets for supplying quenchant at a substantially lower pressure and a substantially higher volume than said first quench means to quench a strip moving through said roll sets at a second relatively high quench rate substantially higher than said first rate.

2. The device of claim 1 and further including a plurality of horizontally spaced backup rolls for said rolls in said other roll set, each of said backup rolls being positioned intermediate and contacting a pair of rolls in said other roll set, said backup rolls being movable toward and away from said rolls in said other roll set, and said biasing means acting on said backup rolls for biasing said backup rolls toward said rolls in said other roll set.

3. The device of claim 1 wherein said one roll set comprises said bottom roll set.

Claims

1. A device for quenching an elongated flat strip comprising; a bottom roll set including a plurality of horizontally spaced rolls of substantially the same diameter, an upper roll set including a plurality of horizontally spaced rolls of substantially the same diameter and of substantially the same diameter as said rolls in said bottom roll set, each said roll in said upper roll set being vertically aligned and parallel with a corresponding roll in said bottom roll set, drive means for driving each roll in one of said roll sets at substantially the same speed in a predetermined direction to move a strip in a predetermined direction through said bottom and upper roll sets, each roll in the other of said roll sets being nondriven and mounted for independent rotation, each said roll in the other of said roll sets being individually mounted for movement toward and away from a corresponding roll in said one roll set, biasing means for independently biasing each roll in said other roll set toward said rolls in said one roll set, and quenching means for quenching a strip moving through said roll sets, said quenching means including a first quench means for supplying quenchant at high pressure and low volume to quench a strip moving through said roll sets at a first relatively slow quench rate, said quenching means including a second quench means spaced from said first quench means in said predetermined direction of travel of a strip through said roll sets for supplying quenchant at a substantially lower pressure and a substantially higher volume than said first quench means to quench a strip moving through said roll sets at a second relatively high quench rate substantially higher than said first rate.