US3662997A

US3662997A - Apparatus for quenching coils

Info

Publication number: US3662997A
Application number: US21735A
Authority: US
Inventors: William M Bloom
Original assignee: Allegheny Ludlum Steel Corp
Current assignee: Allegheny Ludlum Corp; Pittsburgh National Bank
Priority date: 1970-03-23
Filing date: 1970-03-23
Publication date: 1972-05-16
Anticipated expiration: 1989-05-16

Abstract

Apparatus for rapidly and uniformly quenching coils of steel rod, tube or the like from an annealing temperature to a quench temperature by establishing a flow of quenching liquid from the inside of the coil about the wraps to the outside of the coil at a flow rate sufficient that the quenching liquid is maintained in its liquid state. The apparatus includes a quenching bath, means for lowering the coils into the bath, quenching liquid supply means disposed within the central open portion of the coils when lowered in the bath in quenching position, means to collet quenching liquid from around the outside diameter of the coils when in quenching position, and circulating means for providing a forced flow of quenching liquid from the supply means through the wraps of the coil to the collecting means. Preferred embodiments include a means for recirculating the quenching liquid, means for removing heat picked up from the coil wraps and means for controlling the temperature of the bath.

Description

United States Patent Bloom [451 May 16, 1972 Allegheny Ludlum Steel Corporation, Pittsburgh, Pa.

22 Filed: Mar. 23, 1970 21 Appl.No.: 21,735

[72] Inventor:

[73] Assignee:

[52] U.S. Cl. ..266/6 R, 148/143 [51] Int. Cl. ..C2ld 1/62 [58] Field olSearch "148/143, 153; 266/2 R,3R, 266/4R,4A,4B,6R,6S

[56] References Cited UNITED STATES PATENTS 687,716 12/1901 Bennett ..148/143 1,874,300 8/1932 Johnson ..266/6 R 1,959,215 5/1934 Owen ..266/6 R 1,977,989 10/1934 Gassen ..266/6 S 2,484,333 10/1949 Cobb et al ..266/4 R 2,843,514 7/1958 Kunz ..266/4 R 3,490,500 1/1970 Dopper et a1. ..266/3 R Make Up Quenching Primary Examiner-Gerald A. Dost Attorney-Richard A. Speer, Vin ent G. Gioia and Howard R. Berkenstock, Jr.

[ 57] ABSTRACT Apparatus for rapidly and uniformly quenching coils of steel rod, tube or the like from an annealing temperature to a quench temperature by establishing a flow of quenching liquid from the inside of the coil about the wraps to the outside of the coil at a flow rate sufficient that the quenching liquid is maintained in its liquid state. The apparatus includes a quenching bath, means for lowering the coils into the bath, quenching liquid supply means disposed within the central open portion of the coils when lowered in the bath in quenching position, means to collet quenching liquid from around the outside diameter of the coils when in quenching position, and circulating means for providing a forced flow of quenching liquid from the supply means through the wraps of the coil to the collecting means. Preferred embodiments include a means for recirculating the quenching liquid, means for removing heat picked up from the coil wraps and means for controlling the temperature of the bath.

6 Claims, 1 Drawing Figure PATENTEDHAY 16 1972 (HI QN APPARATUS FOR QUENCI-IING COILS BACKGROUND OF THE INVENTION Coils of rod and tube such as those formed from alloy steels have been water quenched by various methods. Conventional methods of quenching coiled rod or tube usually include suspending the coil from a C-hook with the coil hanging vertically over the bath and then dipping the coil into the bath. Those familiar with the art realize that an effective quenching involves the continuous cooling of the article from the annealing temperature to the quench temperature at a rate rapid enough to prevent unwanted transformation of certain microstructure of the alloy. In the case of large coils of rod as well as those more tightly wound, the circulation of quenching liquid is important both to insure an accelerated cooling rate as well as to insure a uniform cooling of the wraps. If the required cooling rate is not maintained for any given section or wrap of a coil, the material in that area may suffer undesired metallurgical change which in turn may generate waste in the quenching operation. Further, if the unsatisfactory flow is continued for a prolonged duration, a change from the liquid to gaseous state; e.g., water to stream of the quenching liquid occur. If this occurs within the wraps of coils being cooled, the uniform cooling of the coil as a whole is interrupted. The change of the liquid to the gaseous state creates gas pockets which impede the flow of the liquid quenching medium through the wraps as well as diminishing the uniform cooling rate which might otherwise be maintained. It will be appreciated by those familiar with the art also that a gaseous medium is generally less capable of carrying heat away from the article to be cooled.

The apparatus of my invention provides adequate quenching or large, tightly wrapped coils of rod and the like by insuring a positive flow of quenching medium among the wraps of the coil and by providing a cooling rate sufficiently accelerated to avoid undesirable metallurgical change of the material as well as a uniform cooling of the wraps of the coils to insure uniform good quality of quenched product.

SUMMARY OF THE INVENTION Apparatus for quenching coils of metal such as rod, tube and the like by a process including lowering the coil into a quenching bath, supplying a quantity of circulating quenching liquid to the bath at the inside diameter of the coil, forcing the flow of the quenching liquid through the wraps of the coil and removing the supplied quenching liquid from the bath in close proximity to the outside diameter of the coil, all the while maintaining the flow rate at a sufficient value to enable the quenching liquid to remain in its liquid state. The apparatus for quenching coils of material such as rod, tube or the like include a quenching bath, a supply means for supplying the quenching liquid in the approximate center of the bath about which the coil to be quenched is placed and collecting means disposed around the outside of said coil to receive the circulating quenching fluid being passed through the wraps of the coil. Preferred embodiments of the apparatus include means to oscillate the coil in a direction substantially perpendicular to the forced flow of the quenching liquid as well as recirculating means to return the quenching liquid from the collecting means to the supply means and including means to remove heat gained by the quenching liquid during the quenching operation.

DESCRIPTION OE THE DRAWINGS The FIGURE is an elevated sectional view of the apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, reference number 2 indicates a quenching tank having a quenching bath 4, such as water, contained therein. The apparatus and method of my invention may be effective with a quenching bath of oil, polyvinyl chloride-water solution, as well as other quenching liquids.

Tank 2 is supported by means 6 well known in the art. Within the approximate center of tank 2 is a quenching liquid supply header 8 being generally cylindrical in shape and having a diameter smaller than the coiled material to be quenched by the bath 4. Supply header 8 has quenching liquid outlet holes 10 located in the periphery of the header and disposed over its surface area adjacent the coil C to be quenched. Header 8 in the preferred embodiment also includes coil centering means 12 such as a cone. The cone 12 is disposed on the top of the heater 8 to center a coil C which may be lowered by means such as elevator means 14 disposed above the quenching tank 2. Disposed around coil C and within tank 2 is quenching liquid collecting heater 16 which in the embodiment disclosed is of a toroidal shape having inlet holes 18 disposed around the inside diameter thereof. Collecting header 16 has an inside diameter larger than a coil C to be quenched such that the coil may be disposed about supply header 8 and within collecting header 16. In the preferred embodiment supply header 8 and collecting header 16 are connected by recirculating means 20 including flow pipe 22 connecting header 16 to pump means 24 and supply flow pipe 26 connecting the recirculating means to header 8. Also within the preferred embodiment is quenching liquid makeup means 28 to supply additional quenching liquid to the system as well as automatic temperature control means 30 with a sensor 32 in the bath to regulate the temperature thereof to the desired level.

The quench of this invention employs a quenching liquid at a controlled flow rate through the coil C having coil wraps W by injecting the quenching liquid into quench bath 4 at its center through a distribution header 8 which may be a cylindrical duct extending upwardly from the bottom of a quench tank 2 into the inside diameter of coil C. Quenching liquid outlet holes 10 extend around the periphery of header 8 and are located so as to supply the quench liquid to the bottom inside of the coil at its lowest position in the quench and the top of the coil in its highest position in the quench, as well as the remainder of the inside coil surface being between the top and bottom of coil C. In the preferred embodiment of the method and apparatus of my invention, means is provided as at 34 to provide a vertical oscillatory motion in coil C within the quench bath 4, the uppermost reach of the oscillation being illustrated at 36 and the lowermost reach thereof illustrated at 38. It will be noted that the quench liquid outlet holes 10 extend over the periphery of the supply header 8 from the lowermost reach of the coil oscillation at 38 to the uppermost reach of coil oscillation 36 in the preferred embodiment.

Hot coils which have exited from a heat treating furnace such as an annealing furnace are conveyed to a position above the quench tank 2 on rollers or conveyor means as at 40. From this position the coils C may be lowered by elevator means 14, over the centering cone 12 of the supply header 8 into bath 4 so that coil C is positioned around the periphery of header 8. Quenching liquid outlet holes 10 are spaced about the periphery of header 8 to cause positive flow of quenching liquid around coil wraps W to the collecting header 16. The collecting header is designed to pull an equal quantity of water through each collecting header inlet hole 18 and return the total quenching liquid collected to the pump means 24 which in turn returns the quenching liquid to the supply header 8. Hence, a positive quenching liquid flow path is established by the pump liquid pressure which forces a quenching liquid through the distribution header outlet holes 10 to blanket the entire inside diameter of the coil C where the quenching liquid is thereby positively and rapidly forced through the void area around the coil wraps W and is in turn drawn by the pump 24 suction through flow pipe 22 and collecting header 16.

The void space around the coil wraps W act as weirs to provide a relatively uniform flow rate of quenching liquid through and around the various adjacent coil wraps, thereby achieving a more uniform cooling rate for each wrap W. The increase of coil flow area because of the expanding circumference of successive wraps as a quenching liquid flows from the inside diameter to the outside diameter co-acts with the loss in liquid flow pressure due to the friction loss of the turbulent flow of the liquid progressing throughthe coil wraps W. The suction drawn by pump 24 pulling the liquid from the collecting header 16 further aids in the establishment of the positive quenching flow path through the coil and around wraps W. It has been found that maintaining a ratio of coil height to coil wrap thickness in the coil C in the ratio of 4:1 establishes an optimum low resistance flow path for the quenching liquid through the coil wraps W rather than around them. Accordingly, the clearance between the supply header 8 outside diameter and inside diameter of coil C is desirably kept at a minimum to prevent excessive loss of quenching liquid out the coil ends as opposed through the coil wraps. Minimization of this space between the coil and header 8 increases the flow pressure of the quenching liquid through the coil. It may thus be appreciated that for adaptability of the header 8 to different coil sizes, it may be desirable to have a sleeving means to slide over the supply header 8 to increase its effective diameter such that it more closely approaches that of larger coil diameters.

l have found that in preferred embodiments, it is desirable to oscillate the coil C in and upward and downwardly motion relative to the lateral flow of quenching liquid. This tends toward a more uniform quench of the coil ends compensating for inlet quenching liquid flow near the ends of the coil actually flowing around out the inside diameter of the coil and around the coil ends rather than through the coil wraps. This oscillation further tends to speed up quench times required for all coil sized by providing additional turbulence in the bath.

In further preferred embodiments, a space 42 is provided in the bottom of the tank 2 in which metal oxides in the form of scale may accumulate. These conventionally flake off coils during quench. Optionally, means should be provided to facilitate removal of the scale from the settling area 42 as by sluicing the scale out through a gate valve into a collector where the scale may settle out and the sluicing liquid returned for service.

It is to be noted that the pump 24 and supply and collecting header holes 10 and 18 should be sufficiently large to prevent scale plugging up and thereby damaging the various components, and the quenching cycle.

The quenching apparatus in the preferred embodiment is provided with makeup liquid and temperature and level controls. The level of liquid may be controlled in the tank 2 by an overflow weir 44. In the example disclosed temperature of the quenching bath is controlled by adding cold quenching liquid to the recirculating system at a rate regulated by the temperature control 30. This causes an increase quantity of bath liquid 4 such that the excess must be drained off through an overflow weir 44. Other means of controlling the temperature of the bath 4 may be utilized, such as an independently operated heat exchanger. In the example disclosed, the liquid being water, is optimally controlled at a temperature of l l-l 30 F. This results in the coils leaving the quench having enough residual heat therein to cause them to relatively quick self-dry. In the example disclosed, the material of the quench tank 2,

supply header 8, collecting header l6 and flow piping 22 and 26 are made of corrosion resistant material such as a stainless steel, thereby extending the service life of the apparatus.

It should be further noted that the bottom of elevator means 14 should open to allow quenching liquid to contact the coil immediately as the coil is lowered into the quenching bath 4. This reduces the required quenching time. In this embodiment rolls as at 40 are advantageous for the elevator means bottom allowing rapid run-off and run-on of the coil C. It will be further appreciated by those familiar with the art that additional adaptations and modifications may be made in the apparatus which do not appreciably depart from the scope of the invention as hereinafter claimed.

I claim:

1. ln apparatus for quenching coils of rod, tube and the like, the combination of a quenching tank, an upstanding generally cylindrical supply header within said tank and around which a coil to be quenched is lowered from a position above the tank,

liquid outlet holes spaced around theperiphery of said header adjacent the inner periphery of a lowered coil to be quenched, a generally annular collecting header surroundingsaid supply header such that a lowered coil to be quenched is between the supply and collecting headers, inlet openings in the collecting header, a liquid quenching bath filling'said tank and the interior of said supply header to a point above said liquid outlet holes in the periphery of said supply header, the openings in said collecting header and a coil to be quenched being immersed in said quenching bath, and means for pumping the liquid of said bath from said collecting header to said supply header whereby the liquid will be forced through the outlet holes in the supply header, through the wraps of a coil positioned between the supply and collecting headers and thence back to the collecting header while said coil is immersed in said quenching bath.

2. The apparatus of claim 1 wherein the upper end of said supply header is closed whereby water pumped into the supply header must pass through said liquid outlet holes.

3. The apparatus of claim 2 wherein the upper closed end of said supply header is conical to facilitate centering and to render a coil to be quenched substantially coaxial with said supply and collecting headers.

4. The apparatus of claim 2 wherein the quenching liquid is pumped into the bottom of said supply header from whence it passes upwardly and through said liquid outlet holes where it flows through a coil to be quenched to said collecting header.

5. The apparatus of claim 1 wherein the liquid passing through said liquid outlet holes in the supply header produces a forced flow of the quenching liquid passing through a coil to be quenched, and including means for oscillating said coil in said liquid quenching bath in a direction substantially perpendicular to said forced flow of liquid.

6. The apparatus of claim 1 wherein said means for pumping forces liquid in said quenching bath through the wraps of a coil positioned between the supply and collecting headers while collecting heat therefrom at a rate less than that required to cause a change of state of the quenching liquid.

Claims

1. In apparatus for quenching coils of rod, tube and the like, the combination of a quenching tank, an upstanding generally cylindrical supply header within said tank and around which a coil to be quenched is lowered from a position above the tank, liquid outlet holes spaced around the periphery of said header adjacent the inner periphery of a lowered coil to be quenched, a generally annular collecting header surrounding said supply header such that a lowered coil to be quenched is between the supply and collecting headers, inlet openings in the collecting header, a liquid quenching bath filling said tank and the interior of said supply header to a point above said liquid outlet holes in the periphery of said supply header, the openings in said collecting header and a coil to be quenched being immersed in said quenching bath, and means for pumping the liquid of said bath from said collecting header to said supply header whereby the liquid will be forced through the outlet holes in the supply header, through the wraps of a coil positioned between the supply and collecting headers and thence back to the collecting header while said coil is immersed in said quenching bath.