US3517676A

US3517676A - Quench apparatus for providing pulsating and sweeping flow of quench fluid

Info

Publication number: US3517676A
Application number: US678073A
Authority: US
Inventors: Byron Paddock Jr
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1967-10-25
Filing date: 1967-10-25
Publication date: 1970-06-30
Anticipated expiration: 1987-06-30
Also published as: FR1590002A

Description

June 1970 B. PADDOCK. JR

QUENCH APPARATUS FOR PROVIDING PULSATING AND SWEEPING FLOW OF QUENCH FLUID 2 Sheets-Sheet 1 Filed Oct. 25, 1967 INVENTOR. BYRON PADDOCK JR.

ATTORNEYS June 30, 1970 B. PADDOCK, JR 3,517,576

QUENGH APPARATUS FOR PROVIDING PULSATING AND SWEEPING FLOW 0F QUENCH FLUID I Filed Oct. 25, 1967 2 Sheets-Sheet i; sscorw I400 IOOO- SECOND; q

TIME

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BYRON PADDOCK JR.

BY 1 f 511-4 ATTORNEYS United States Patent QUENCH APPARATUS FOR PROVIDING PULSAT- ING AND SWEEPING FLOW OF QUEN CH FLIJID Byron Paddock, Jr., McLean County, Ill., assignor to Caterpillar Tractor Co., Peoria, 111., a corporation of California Filed Oct. 25, 1967, Ser. No. 678,073 Int. Cl. C21d 1/64 US. Cl. 134-199 7 Claims ABSTRACT OF THE DISCLOSURE A quench system in which quenching fluid directed through orifices of a quench tube onto parts being quenched has pulsating and sweeping characteristics which are selectively variable to improve quench properties of the parts. Quench fluid is provided to the orifices through accumulators and a butterfly valve to cause flow variations which result in the fluid passing through the orifices as pulsating jets. A pair of valves control flow from the bottom of the quench tube and overflow from the top of the quench tube respectively so that the jets of quench fluid from the orifices may be caused to sweep the parts being quenched in a variable direction.

A common quench system typically comprises a quench region in which heated parts are placed for quenching. Quenching fluid fills the quench region while additional fluid is directed toward the parts through orifices to serve at least two purposes. Firstly, the additional fluid replaces fluid which has been raised above the desired temperature range by heat transfer from the parts. Secondly, the fluid from the orifices is under pressure and acts as a jet to interact with fluid in the quench region and cause turbulence for better surface wetting of the parts.

Continuous wetting of the parts is of critical importance since it is desirable to maintain the quench fluid in contact with the entire surface of the parts throughout the quenching operation to achieve uniform cooling. Such uniform cooling is particularly desirable, for example, within the martensitic transformation range to insure proper transformation within the parts as their temperature is lowered. If uniform cooling is not maintained, uneven stresses may develop which would cause distortion of the parts or impair their strength.

However, continuous wetting is difficult to achieve because the much greater temperature of the part, upon contacting the fluid, tends to vaporize the fluid and create a vapor barrier between the part and the fluid. This vapor barrier must be effectively broken so that the fluid may remain in contact with the parts. Turbulence caused by fluid entering the quench region in jet form through the orifices and interacting with other fluid has been found inadequate, in varying degrees, to effectively break up the vapor barrier and provide continuous wetting. One explanation for the inadequacy of the previously employed orifices (as well as commonly employed stirrers and agitators) is that the fluid, acting under generally constant pressure, enters the quench region as a steady flow jet and does not achieve maximum turbulence upon interaction with other fluid therein.

A principle object of the present invention is to provide a valve means which interact with the quench fluid prior to its entering the quench region and vary the flow rate with which the fluid passes through the orifices to provide a pulsating characteristic in the fluid jets. Resulting increased flow interference between the jets and additional fluid about the heat treated parts causes increased turbulence within the quench region and particularly 3,517,676 Patented June 30, 1970 'ice about the surfaces of the parts. The increased turbulence caused by interaction of the pulsating jets with fluid in the quench tube is particularly desirable to accomplish uniform cooling of parts having complex shapes such as splines, collars, notches, etc.

An additional disadvantage of the prior art quench systems of this type arose from the practice of permitting the quench fluid to overflow from the top of a chamber forming the quench region. This generally resulted in higher fluid temperatures at the top of the chamber compared with its lower portions and accordingly in uneven cooling of the part surfaces. Further, with all fluid being removed from the top of the chamber, the vapor tended to form a cone or vortex at the top of the chamber and prevent proper cooling within that region.

Accordingly, a further object of the invention is to employ valve means for controlling fluid flow from at least the base of the chamber so that hot fluid could be removed from the base of the quench chamber to maintain a generally uniform fluid temperature along its vertical length. Preferably, valve means are also employed to regulate fluid overflow from the top of the tube so that fluid could be alternately removed from the topand base of the chamber. Thus, the fluid jets entering thejorifices could be caused to sweep back and forth over the parts to provide further increased turbulence, more rapid and more complete dispersion of the vapor barrier and a more uniform fluid temperature within the tube.

Another object is to provide variable valves for controlling fluid flow to the orifices and controlling flow from the quenching chamber to permit varied combinations or varying sequences of the pulsating and sweeping characteristics described above during quenching operations.

Other objects and advantages of the present invention are made apparent in the following description where the invention is described with reference to the accompanying drawings wherein:

FIG. 1 is an isometric view, with parts in section, of quenching apparatus embodying the present invention;

FIG. 2 is a graphical representation of variations of fluid flow to the orifices to create fluid jets with pulsating characteristics; and

FIG. 3 is a schematic representation of the apparatus of FIG. 1.

The apparatus illustrated in FIG. 1 comprises a quench tank 11 in which a quench tube 12 is centrally disposed to receive a basket 13 containing heated parts which are to be submitted to the quenching operation. The quench tube has an outer jacket 14 forming a concentric fluidtight manifold 16 about the tube for receiving a suitable quenching medium such as oil. When the basket 13 is lowered within the quench tube, the quenching fluid is directed from the manifold into the quench tube and toward the parts through high pressure jets which are preferably orifices, for example, of /8 inch diameter, drilled in spaced relation through the quench tube 12 as partially indicated at 17. Quenching fluid is delivered to the manifold 16 from a pump 18 through a conduit 19 and

branch conduits

21 and 22 communicating with opposite sides of the manifold. Quench fluid which is to be exhausted from the quenching tube is returned to the pump by

return conduits

23 and 24 which are generally in communication with the interior of the quench tank 11 and pump inlet 25.

To increase the severity of quench caused by the quenching medium entering the tube 12 through the orifices 17 and to permit variations within the quenching operation according to the present invention, a variable valve such as a butterfly valve 26 is disposed across the inlet conduits 19 to regulate fluid flow from the pump. The valve is driven in rotation by a motor 27 through a speed reducer drive assembly 28. Rotation of the butterfly valve, between its open and closed positions, varies the rate of flow from the pump 18 and accordingly causes pressure variations in the quenching medium contained in the manifold 16. Thus the quenching medium entering the quench tube through the orifices 17 has a pulsating characteristic so that its interaction with quenching fluid already in the tube causes increased turbulence. To further increase turbulence by further increasing fluid flow variations to the manifold 16, fluid pressure accumulators. 29 are communicated through a conduit 31 with the inlet conduit 19 between the butterfly valve 26 and the fluid pump 18. With the-butterfly valve rotating between its open and closed positions, the accumulators are charged when the butterfly valve is closed so that when the butterfly valve reaches its open position, the maximum flow rate to the manifold 16 is substantially increased and the maximum velocity of the quench medium through the orifices 17 is increased by as much as 50% over its maximum velocity when dependent upon the capacity of the pump alone. It may be noted that a large capacity pump could provide the same differential rangeof flow rate and jet velocity without the use of accumulators; however, the accumulators increase the efliciency of the quench system by permitting the use of a smaller capacity pump which reduces both the size of the installation and the capital investment required.

Further variable control over the quench operation is provided by the means with which quenching medium is exhausted from the quench tube. The fluid return conduit 23 is communicated at 32, see FIG. 3, with the interior of the quench tube, generally at the bottom thereof, while the other fluid return conduit 24 is communicated at 33 with the quench tank 11 outside of the quench tube 12 and its manifold 14. Fluid flow through the return conduit 23 is regulated by a valve 34 which has a servo control unit 36. A similar valve 37 and control unit 38 are disposed across the other fluid return conduit 24. When the valve 34 is open, quenching fluid is exhausted downwardly from the quench tube through .the return conduit 23. The valve 37 controls the rate at which overflow fluid parent that in either of the above modes of operation,

from the quench tube is returned to the pump 18. An-

other valve 39 is disposed across conduit 23 to shut down quench flow for cleanup or repairs for example.

The great variety of quench operations possible within the above system is readily apparent from a consideration of the individual and combined modes of operation of the butterfly valve 26 and the

outlet valves

34 and 37. As for the butterfly valve 26, it may be operated in rotating fashion between its open and closed position at varying frequencies or it may be operated continuously in either its open or closed position. Greatest turbulence is created within the quench tube from relatively rapid rotation of the butterfly valve as may be seen from the fluid velocity trace illustrated in FIG. 2. Tests have indicated that with a 15 HP quench pump and approximately 300 A; inch diameter orifices on the quench tube wall with a 120 r.p.m. pump drive, it is possible to vary quench fluid flow to the manifold 16 from less than 200 g.p.m. to 1400 g.p.m. with a frequency of /a second. The high and low velocity limits occur respectively during rotation of the butterfly valve when it is at its open position and its closed position. If the butterfly valve is continuously open, turbulence created in the quench tube will be less, since the pulsating character and peak velocities of the fluid jets are not present. The butterfly valve may also be operated continuously in its closed position which results in an overall reduction of the flow rate of quenching fluid into the manifold and quench tube with a great reduction of turbulence within the quench tube. Generally, the greatest turbulence or quench severity is desired at least during the initial quenching stages of the heat treated the direction of exhaust flow from the tube would cause the fluid jets entering the tube through the orifices 17 to sweep either upwardly or downwardly along the surfaces of the parts disposed therein for quenching. Another mode of operation consists of alternating both of the

valves

34 and 37 between their open and closed positions so that the valve 34 is open when the valve 37 is closed and Vice versa. In this manner, the exhaust flow of the fluid from the tube and the sweeping direction of the fluid jets would be alternated between an upward and a downward direction. Yet another mode .of operation is permitted by placing both of the

valves

34 and 37 in an open position whereby quenching fluid in the tube is exhausted both upwardly and downwardly therefrom. This mode of operation is generally illustrated in FIG. 3 and provides a setting for describing still another operational variation of the present quench system. In FIG. 1, the orifices 17 are illustrated as being generally uniformly spaced upon the surface of the quenching tube so that fluid jets are uniformly directed throughout the interior of the quenching tube. However, the quenching tube is readily replaceable within the quenching tank so that the arrangement of the orifices is also readily interchangeable. For example, the orifices maybe concentrated upon a portion of the quench tube to direct a concentration of jet streams into an area of the quench tube containing the greatest mass of parts to be quenched. If the greatest mass of quench parts were centrally disposed along the lengths of the tube with a lesser mass at either end there of, for example, the orifices could be concentrated about a midpoint of the tube to provide the most severe quench or greatest turbulence thereat. With both of the

valves

34 and 37 open, fluid would be exhausted from both ends of the tube providing a temperature gradient within the quench tube having the lowest temperature at the midpoint and uniformly varying to a higher'temperature at either end. This gradation of quench severity and temperature, considered together with the exemplary mass arrangement of the quench parts described above would result in more uniform quenching of the entire part or parts. The variations described above for operation of the various components of the quench system may also be combined and interchanged to permit a great variety of possible quenching operations. These singular and combined variations may be employed within a single quench cycle to achieve greater uniformity of quench or they may be employed to adapt the system for quenching of parts which vary in size and shape from quench cycle to quench cycle.

El claim:

1. In quench apparatus of a type where heat treated parts are to be placed in a quenching chamber and jet means are to receive quenching fluid from a pump and direct it, in the form of pressurized fluid jets, toward the parts, the fluid jets interacting with other quenching fluid about the parts, the improvement comprising a variable valve interposed between the pump and the jets to vary the velocity with which the jets of quenching fluid are directed from the jet means so that interaction of the fluid jets with the other quenching fluid about the parts causes substantially increased turbulence therein, and further comprising means for of its cyclical operation is selectively controllable. 1

3. The quench apparatus of claim 2 further comprising at least one fluid accumulator disposed between the pump and said variable valve.

4. The quench apparatus of claim 2 where the quench chamber is open at its top to receive the parts to be 15 quenched, a generally fluid-tight manifold in communication with the pump is partially formed by sidewalls in the quench chamber, an overflow chamber surrounds the quench chamber and manifold and the jet means communicate the manifold and quenching chamber, wherein 20 said means for selectively removing quenching fluid com prises a first return conduit and valve communicating the interior of the quenching chamber generally at the bottom thereof with the pump and a second return conduit and valve communicating the overflow chamber with the 25 pump.

I 5. The quench apparatus of claim 4 wherein servo controls are associated with said first and second valves to selectively regulate the first and second return valves, singly or in any combination, between open and closed positions.

6. The quench apparatus of claim 4 wherein said jet means comprises a multiplicity of orifices formed by said quenching chamber sidewalls and disposed in preselected spacing thereupon.

7. The quench apparatus of claim 4 wherein said variable valve is a butterfly valve having drive means for selectively regulating the butterfly valve between its open and closed positions.

References Cited UNITED STATES PATENTS 1,899,495 2/1933 Celaya 134-199 2,264,301 12/1941 Denneen et al. 134199 2,625,945 1/1953 Secor 134199 2,867,226 1/ 1959 Williams et al. 134- 199 2,947,312 8/1960 Heinicke 13419 9 X 3,007,478 11/1961 Leonhardt et al. 134-191 X FOREIGN PATENTS 1,292,518 3/1962 France.

ROBERT L. BLEUTGE, Primary Examiner US. Cl. X.R. '2666