US3242017A - Method for heat treating annular castings - Google Patents

Description

March 22, 1966 w. N. HEFLIN, JR 3,242,017

METHOD FOR HEAT TREATING ANNULAR CASTINGS Filed May 5, 196K INVENTOR.

March 22, 1966 w. N. HEFLIN, JR 3,242,017

METHOD FOR HEAT TREATING ANNULAR CASTINGS Filed May 5, 1963 2 Sheets-Sheet 2 311 8 126 132 J30 11a 13a wws United States Patent Dflice 3,242,617 Patented Mar. 22, 1966 3,242,017 METHGD FOR HEAT TREATlNG ANNULAR CASTENGS William N. Harlin, Jr., Elrnhurst, Ill, assignor to Amsted Industries Incorporated, hicago, 111., a corporation of New Jersey Filed May 3, 1963, Ser. No. 277,756 6 Claims. (Cl. 148-146) This invention relates generally to the production of annular ferrous castings, such as cast steel wheels, and more particularly to a novel method and apparatus for heat treating such castings in order to obtain increased hardness and ductility in selected portions of such castings.

In the production of cast steel railway wheels, it has been common practice to normalize the wheels by heating them above the critical temperature range of the metal (approximately 1260 to 1350 F.) and then allowing them to cool in air. Normalizing of such cast steel Wheels was performed in order to enhance certain physical characteristics, such as resistance to impact and abrasion.

However, the normalizing of cast steel wheels has not proven to be entirely satisfactory. Various factors, that are controlled only with difliculty, influence the results obtained through normalizing. For example, in order to achieve maximum benefits of normalizing and avoid the creation of undesirable residual stresses, all portions of the cast steel wheel should be cooled through the critical temperature range at approximately the same rate in order to have substantially uniform rates of contraction in all portions of the wheel.

Air cooling of wheels, as is required in the conventional normalizing process, is not entirely compatible with the above requirements because of the great variations in metal thickness as between the wheel rim, plate and hub.

Accordingly, it is an object of this invention to provide a novel method of heat treating cast steel wheels so as to achieve greater hardness and ductility than that previously attainable.

Another object of this invention is to provide a novel method of heat treating cast steel wheels so as to obtain increased hardness and ductility in selected portions of cast steel wheels.

A further object of this invention is to provide a novel apparatus for carrying out the above methods.

Other objects and advantages will become apparent when reference is made to the following written description taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a fragmentary top planview of a spraying arrangement for carrying out the teachings of this invention;

FIGURE 2 is a cross-sectional view taken substantially on the plane of line 2-2 of FIGURE 1 and looking in the direction of the arrows;

FIGURE 3 is a fragmentary partially sectioned view taken substantially on the plane of line 33 of FIGURE 2 and looking in the direction of the arrows; and

FIGURE 4 is a cross-sectional view illustrating a suitable spraying assembly for carrying out the teachings of this invention.

Certain details are omitted from one or more figures for purposes of clarity.

Referring now in greater detail to the drawings, FIG- URES 1 and 2 illustrate an arrangement for toughening wheel rims comprised of a base supporting a water collecting tank assembly 12, turntable assembly 14 and a sprayer assembly 16.

Base 10 may be comprised of a plurality of vertically extending legs 18 the upper ends of which are connected to each other by an annular capping member 20 secured thereto as by welding. Supporting arms 22 and braces 24 are provided intermediately of legs 18 for supporting a lower bearing mounting block 26 adapted to receive a suitable bearing 28 therein.

A pair of laterally extending support members 30, each secured at their ends to the annular capping member 20, are provided for supporting an upper bearing mounting block 32 which is adapted to receive a suitable bearing 34 therein.

A vertically extending drive shaft 40, journalled within bearings 28 and 34, and provided with a shoulder portion 36 to prevent downward movement thereof, is connected by any suitable means, such as a key 38, to the turntable assembly 14.

The turntable assembly 14 is comprised of a generally rectangular table 42 having formed thereon a downwardly depending portion 44 with provisions for closely receiving the upper end of said drive shaft 40 therein. Table 42 is provided with longitudinally extending guide members 46 and 48 having their respective inner guide surfaces 50 and 52, respectively, substantially parallel to each other.

A journal member 54, such as a conventional pillow block, secured to table 42 receives an adjusting screw 56 having rightand left-hand threaded portions 58 and 60, respectively. Clamping blocks 62 and 64, each partially received between guide surfaces 50 and 52, are provided with internally threaded portions as by securing thereto rightand left-hand threaded nuts 66 and 68, respectively which threadably receive the adjusting screw 56.

Preferably, each end of adjusting screw 56 is provided with a driving slot 70 whereby screw 56 may be rotated to move clamping blocks 62, 64 either toward or away from each other.

The Water collecting tank 12 may be comprised of a generally cylindrical vertically extending wall 72 to which is secured, at its lower end, an annular bottom plate 74. A second continuous wall 76 extends vertically upwardly from an inner opening 78, appropriately formed in plate 74 to closely receive legs 18 therethrough. Preferably, Wall 76 is extended sufficiently upwardly so as to abut against the lower edge of capping member 20. All joints of the water tank should of course be made water tight. A radially extending annular cover plate 80 is placed about block 32 and atop both capping member 20 and transversely extending supports 30.

A plurality of mounting brackets 82 are secured to the interior of wall 72. Supporting arm assemblies 84, comprised of end plates 86 and 88 securing together oppositely disposed lengths of angle iron 90, are, in turn, connected between capping member 20 and mounting brackets 82. V

Sprayer assembly 16, comprised of an annularly formed conduit 92 serving as a manifold for a plurality of nozzle assemblies 94 connected thereto, is preferably supported by four rod members 96 slidably received with adjustable rod support members 98. Each of the rod support members is retained between the lengths of angle iron and adjustably secured thereto by means of oppositely disposed radially extending threaded rod portions 100 re ceived through slots 102 formed in angle iron 90. Nozzles 94 are preferably of the adjustable type, having possibly a swivel-like joint, permitting the adjustment of each nozzle so as to obtain the desired angle of discharge therefrom. In the preferred form of the invention, as illustrated, sixteen nozzle assemblies would be substantially equally spaced about manifold 92.

A supply conduit 104, having a valve 106 serially connected therein, communicates between a source 108 of cooling fluid and manifold 92. Bottom plate 74 may also be provided with an orifice 109 through which the spent cooling fluid can drain to a suitable vessel.

A conventional flexible coupling 110, right angle speed reducer 112, fluid coupling 114 and a prime mover 116 may be employed in an arrangement as shown for rotating drive shaft 40.

Operation The operation of the invention is briefly as follows. The annular casting, in this case cast steel railway wheel 118 is preferably heated to a temperature of approximately 1550 to 1600 F. and placed upon the turntable assembly 14. Clamping screw 56 is turned causing jaws 120 of clamping blocks 62 and 64 to move against the outer diameter of the wheel hub portion 122.

Prime mover 116 is then activated thereby rotating shaft 40 causing the turntable assembly 14 and wheel 118 to be rotated about centerline 124. Valve 106 is opened allowing source 108 to force a suitable cooling fluid, such as water, through conduit 104, manifold 92 and nozzles 94 against rim portion 126 of wheel 118 in a spray as generally illustrated at 128.

Wheel 118 is continually rotated and spray 128 ap plied thereto until the temperature of the wheel is brought to below the critical temperature range. Preferably, the water spray is continued until the wheel is at a temperature of between approximately 400-700 F. The increased cooling resulting from the water spray causes the rim tread to have a very fine perlitic structure with both increased hardness and ductility as compared to the air cooled wheels of the prior art.

As was previously mentioned, care must be taken to cool both the thick and thin sections of the wheel at approximately the same rate through the critical temperature range. This is much more easily accomplished by the use of the invention. The continual rotation of Wheel 118, at relatively high speeds, prevents the Water spray impiging upon rim 126 from progressing inwardly upon plate 130 towards the hub portion 122. That is, all the spent cooling fluid is thrown off rim 126 in an outward direction.

A still further beneficial effect is obtained from the rotation of wheel 118. As between any two radially spaced points on wheel 118, the point closer to the axis of wheel 118, has a linear velocity less than that of the point further away. This is true even though the angular velocity of wheel 118 remains constant. The linear velocity of any point on the wheel is proportional to its distance from the axis of rotation. Accordingly, since the static pressure of a fluid is, among other things, dependent on its relative velocity (the higher the velocity, the lower the static pressure) it can be seen that the static air pressure nearer the hub diameter is greater than that nearer the rim portion.

Therefore, a pumping action is created by Wheel 118 which results in a flow of air over hub 122 and plate 130 having a pattern illustrated generally by the heavy shaded arrows 132. Likewise, the bore 136 has an air flow pattern therein illustrated by arrows 134.

The air flows, as described above, aid in the removal of heat from both the plate 130 and hub 122. That is, the rate of heat dissipation is greater than would otherwise be obtained in a relatively stagnant ambient atmosphere.

After the wheel has cooled to a temperature of between 400 to 700 F., as described, it is then removed from the turntable assembly 14 and reheated to a temperature of approximately 900 F. in order to temper the castings and remove undesirable stress therefrom. Reheating of the wheel, of course, does not in any way adversely affect the microstructure of wheel tread surface as created by the water spray.

The wheel, after being reheated to approximately 900 F., is then placed on a suitable supporting structure 138 (FIGURE 4). A bore spraying nozzle assembly 140 is then introduced into bore 136 as illustrated. The nozzle assembly 140 is preferably comprised of a generally circular flange 142 secured to a vertically depending manifold 144 having formed therein a conduit 146 which communicates with a plurality of axially spaced radially directed spray nozzles 148. Conduit 150, having a valve 152 serial- 1y connected therein, communicating with a suitable source 154 of cooling fluid, in this case water, serves to convey the cooling fluid to conduit 146 and subsequently to nozzles 148.

After the reheated wheel is placed on support 138 and nozzle assembly 140 inserted therein, valve 152 is opened permitting source 154 to force cooling water through spray nozzles 148 against the hub bore 136. Preferably, the spray of water is continued until the temperature of the wheel is again reduced to 400 to 700 F. The final water spraying of the hub serves to create favorable internal stresses within the wheel. That is, when the wheel is finally completely cooled, the plate portion is placed in both a state of radial and circumferential compression.

Although but one form of the invention has been disclosed and described, it is apparent that other arrangements within the scope of the appended claims can be employed for practicing the invention.

I claim:

1. A method of cooling a heated ferrous article having portions of relatively different thicknesses including a relatively thick radially outer portion and a relatively thin radially inner portion, comprising rotating the article, applying cooling liquid to the radially outer thick portion while rotating the article, and maintaining the rotation thereof at such rate that the cooling liquid is prevented from flowing onto the thin portion and a current of air is established and the air flows radially outwardly and produces a lesser cooling effect on the thin portion than the liquid produces on the thick portion.

2.. A method of cooling a heated ferrous wheel having a relatively thin plate and relatively thick rim, comprising rotating the wheel on a vertical axis, applying cooling liquid radially inwardly on the rim while rotating the wheel, and maintaining the rotation thereof at such rate that a current of air is established and the air flows radially outwardly and produces a lesser cooling effect on the plate than the liquid produces on the rim.

3. A method of treating a cast steel article which includes portions of different thicknesses, comprising heating the article to approximately 1550 to 1600 F., cooling all portions of the article at a substantially equal rate to between approximately 400 to 700 F., again heating the article to approximately 900 F., and thereafter again cooling all portions of the article at a substantially equal rate to between approximately 400 to 700 F.

4. A method of treating a cast steel Wheel having a thick rim, a thin plate, and a thick hub having a central axial hole, comprising, heating the wheel to approximately 1550 to 1600 F., cooling the wheel to between approximately 400 to 700 F. by applying cooling fluids thereto including applying a liquid to the rim and air to the plate, again heating the wheel to approximately 900 F., and thereafter again cooling the article to between iaip groxirnately 400 to 700 F. by applying liquid to the 5. A method as set outin claim 4 wherein the wheel is rotated on a vertical axis in the first cooling step and in such step liquid is sprayed inwardly on the hub while rotating the wheel, and the rotation is maintained at such rate that the liquid is prevented from progressing to the plate and a current of air is established and the air flows outwardly over the plate, and in the second cooling step liquid is sprayed on the hub in the central axial hole.

6. A method of treating a cast steel wheel having a thick rim, a thick hub having a central axial hole, and a thin plate intermediate said rim and hub, which comprises heating the Wheel to about 1550 to 1600 F., cooling the Wheel to about 400 to 700 F. by spraying said rim with a cooling liquid from a plurality of spaced positions about the periphery of the wheel while rotating the wheel about a vertical axis, the wheel being rotated at a rate to prevent said cooling liquid from progressing to said plate and to establish a current of air flowing over said plate, again heating the wheel to about 900 F., and thereafter again cooling the Wheel to about 400 to 700 F. by spraying a cooling liquid on said hub in the central axial hole.

References Cited by the Examiner UNITED STATES PATENTS 9/1921 Schalfer 8/1943 Dimmick Wishart 148-I46 Penrod 134123 Ayres 266-4 Bridge et a1. 148-448 Dewez 148-143 DAVID L. RECK, Primary Examiner.

Claims (1)

1. 3. A METHOD OF TREATING A CAST STEEL ARTICLE WHICH INCLUDES PORTIONS OF DIFFERENT THICKNESSES, COMPRISING HEATING THE ARTICLE TO APPROXIMATELY 1550* TO 1600*F., COOLING ALL PORTIONS OF THE ARTICLE AT A SUBSTANTIALLY EQUAL RATE TO BETWEEN APPROXIMATELY 400* TO 700*F., AGAIN HEATING THE ARTICLE TO APPROXIMATELY 900*., AND THEREAFTER AGAIN COOLING ALL PORTIONS OF THE ARTICLE AT A SUBSTANTIALLY EQUAL RATE TO BETWEEN APPROXIMATELY 400* TO 700*F.

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