US3505133A - Roll heat treating method - Google Patents

Description

April 7, 1970 J. H. SONEKI ET AL 3,505,133

ROLL HEAT TREATING METHOD INVENTORS .9 Joseph H. Sane/(i Lk Rober/ L. Myers J. H. SONEK] ET AL 3,505,133 ROLL HEAT TREATING. METHOD 6 Sheets-Sheet 5 S R O T N E V N l Joseph H. Sane/n Haber! L Myers April7, 1970 Original Filed Aug. 4. 1967 April 7, 1970 J, H, so ET AL 3,505,133

ROLL HEAT TREATING METHOD 6 Sheets-Sheet 4 Original Filed Aug. 4, 1967 IN VE N TORS Joseph H Soneki Rober/L. Myers April 7, 1970 J. H. SONEKI ET ROLL HEAT TREATING METHOD 6 Sheets- Sheet 5 Original Filed Aug. 4, 1967 m I I I I I I n I INVENTORS Joseph H Sane/0' Roberf L Myers p -7, 1970 J. H. SCVDNEKI ETAL 7 3,505,133

ROLL HEAT TREATING METHOD Original Filed Aug. 4, 1967 6 Sheets-Sheet 6 Surface of Rol/ Bore of Roll Zero Stress Compress/'00 INVENTORS Joseph H. Sane/r1 Roberf L. Myers United States Patent O 3,505,133 ROLL HEAT TREATING METHOD Joseph H. Soneki, Bethlehem, and Robert L. Myers,

Coopersburg, Pa., assignors to Bethlehem Steel Corporation, a corporation of Delaware Application Aug. 4, 1967, Ser. No. 658,403, which is a continuation-impart of application Ser. No. 658,097, Aug. 3, 1967, which in turn is a division of application Ser. No. 575,736, Aug. 29, 1966. Divided and this application Apr. 9, 1969, Ser. No. 814,688

Int. Cl. C21d 1/06 US. Cl. 148-143 4 Claims ABSTRACT OF THE DISCLOSURE A carriage, vertically movable with respect to fixed heating and quenching rings, vertically supports a roll having a bore therein. A coolant is forced upwardly through the bore while the roll is progressively heated and quenched by driving the roll downwardly through the rings. After quenching, the roll is submerged in a coolant and laterally repositioned therein.

CROSS-REFERENCES TO RELATED APPLICATION This application is a division of application Ser. No. 65 8,403, filed Aug. 4, 1967, which is itself a continuationin-part of application Ser. No. 658,097 now abandoned, filed Aug. 3, 1967, which is itself a division of application Ser. No. 575,736, filed Aug. 29, 1966.

BACKGROUND OF THE INVENTION This invention relates to the heat treatment of ferrous metal rolls, and more particularly to a method for hardening the outer shell of quench-hardenable steel rolls.

Large steel rolls are usually manufactured by forging steel into the desired shape and then heat treating the steel shape to impart a high degree of hardness to the outer shell thereof. In order to obtain the desired hardness, it is necessary to heat the outer shell to a temperature above the upper critical temperature and then quench the outer shell to convert the microstructure thereof into martensite.

It is desirable for the inner portion of the roll to be tough and ductile and as free from stresses as possible. Preferably, the heat treating operation is controlled to insure that the inner portion of the roll is substantially unaffected by the hardening of the outer shell.

Inasmuch as the volume of martensite is different from that of the microstructure of the unhardened portion of the roll, stresses are introduced into the roll by the quenching operation. If these stresses are in an unfavorable pattern, premature failure of the roll may occur.

In addition to transformational stresses, i.e., those due to changes in microstructure, thermal stresses are induced in the roll due to changes in temperature throughout the body of the roll during the heat treatment thereof.

It is an object of this invention to provide a method for hardening the outer shell of steel rolls whereby the stress patterns in the hardened roll are favorable.

Another object of this invention is to provide a method whereby steel rolls can be rapidly and efficiently heat treated.

An additional object of the invention is to provide a method for heat treating steel rolls having a bore therein whereby tensile stresses, whether thermal or transformational in origin, are minimized in the metal adjacent to the bore.

SUMMARY OF THE INVENTION We have discovered that the foregoing objects can be attained by vertically supporting a roll on a carriage, pro- 3,505,133 Patented Apr. 7, 1970 'ice viding means for concurrently heating a first annular Zone of said roll and quenching a second, contiguous annular zone of said roll, and by providing additional means as will hereinafter be described and claimed.

In the preferred embodiment, a coolant, the purpose of which is to minimize any substantial change in the temperature of the metal adjacent to the bore during the hardening of the exterior of said roll, is formed upwardly through the bore of the roll while the roll exterior is being heated and quenched.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURES l and 2 are front and side elevations, respectively, of the apparatus of the invention.

FIGURES 3 and 4 are sectional views taken along the lines 33 and 44, respectively, of FIGURE 1.

FIGURE 5 is an enlarged front elevation showing details of the apparatus shown in FIGURE 1, while FIG- URES 6 and 7 are sectional views taken along the lines 66 and 77, respectively, of FIGURE 5.

FIGURES 8 and 9 are plan and side elevation views, respectively, showing details of the invention.

FIGURE 10 is a plan view showing further details of the invention.

FIGURE 11 is an enlarged front elevational of rollholding means, while FIGURE 12 is a sectional view taken along the lines 12--12 of FIGURE 11.

FIGURE 13 is a graph showing the idecdized stress patterns of rolls heat treated with and without bore cooling.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to FIGURES 1 and 2, a framework 10 is disposed above a chamber 12 containing a coolant 14, e.g. water. The framework 10 comprises a plurality of columns 16 the upper ends of which are connected by longitudinal beams 24 and by transverse beams 28. The framework 10 is rigidified by a plurality of trusses, not shown.

As shown in detail in FIGURE 3, intermediate the transverse beams 28 is a plurality of transverse supporting beams 34, 36, 38, 40, 42, and 44. Horizontally mounted on beams 38 and 40 is a bearing plate 46 upon which a main drive motor 48, a brake 50, and a miter gear unit 52 are mounted. The miter gear 52 is connected, through suitable shafts and couplings to miter gears 54 and 56. Gear 54 is mounted on a bearing plate 58 disposed across beams 34 and 36. Gear 56 is mounted on a bearing plate 60 disposed across beams 42 and 44.

Affixed to the forward longitudinal beam 24 are supporting means 62 and 64 upon which gear reducers 66 and 68, respectively, are mounted. The gear reducer 66 and 68 are connected to the gears 54 and 56, respectively, by suitable shafts and couplings, and are adapted to drive screws 70 and 72, respectively. Energization of the motor 48 results in the synchronous rotation of screws 70 and 72.

Vertically disposed above the chamber 12 are guide members 74 and 76. Similar guide members 78 and 80 are vertically disposed within the chamber 12. Guide members 74 and 78 are provided with beveled bearing surfaces 82, while members 76 and 80 are provided with flat bearing surfaces 84. Attached to the base of members 74 and 76 are supports 86 for bearings 88 in which the lower ends of the screws 70 and 72 are disposed.

A carriage 90 is adapted to be driven vertically along the framework 10. The carriage 90 broadly comprises a plurality of vertical members 92, and upper crosshead 94, a lower crosshead 96, and a plurality of trusses, not shown.

As shown in detail in FIGURE 4, mounted on the upper crosshead 94 are two fixed ball nuts 100 each of which threadedly engages one of the screws 70 and 72. Suitable bearings 102, mounted on each end of the upper crosshead 94, slidably engage the bearing surfaces 82 and 84.

Mounted on the lower crosshead 96 is means 104 for supporting a vertically disposed roll 106. Means 104 broadly comprises a main housing 108 in which a fluid motor, not shown, is mounted. The fluid motor is adapted to rotate a bottom center post 112 in the housing 108. The bottom center post 112 is provided with a bore, and has a conical upper section which is adapted to be disposed in fluid-tight engagement with the lower end of the bore 116 of the roll 106, said lower end being beveled. The bottom center post 112 is provided with a plurality of holes 118, disposed below the level of the coolant 14, through which the coolant can flow into the bore of the bottom center post 112. Suitable bearings 117, mounted on each end of the lower crosshead 96, slidably engage the bearing surfaces 82 and 84.

Disposed between the upper and lower crossheads is a length adjust crosshead 120. As shown in detail in FIGURES 5, 6 and 7, crosshead 120 comprises a horizontal supporting structure 122 upon which a motor 124 is mounted. The motor 124 is connected, through suitable shafts, couplings, gears, etc., to a pair of rotatable ball nuts 126 mounted on the crosshead 120. The ball nuts 126 threadedly engage the screws 70 and 72. Suitable bearings 128, attached to each end of the crosshead 120, slidably engage bearing surfaces 82 and 84. Energization of the motor 124 results in vertical movement of the crosshead 120 relative to the carriage 90.

Mounted on the crosshead 120 is means for clamping the upper end of a vertically disposed roll. Said means comprises a forwardly-extending housing 130 to which an arm 132 is pivotally connected by means of sleeves 134 journaled on a pin 136. Rigidly aflixed to the arm 132 are bracket plates 138 to which a rod 140 is pivotally connected by means of a pin 141. The rod 140 is connected to the piston of a hydraulic cylinder .142 which is pivotally supported in the housing 130 by bracket plates 144 and pin 145.

Mounted near the lower end of the arm 132 is a plate 146 provided with a hole 148. Mounted on the rear of crosshead 120 is a hydraulic toggle clamp 150, shown in detail in FIGURE 8, comprising a rod 152 adapted to be driven through the hole 148 when the pivot arm 132 is in its raised position by reason of the retraction of rod 140. The toggle clamp 150 provides positive means for maintaining the arm 132 in its raised position in the event that the hydraulic cylinder 142 should malfunction.

Mounted on the lower end of arm 132 are clamping elements 154 and 156. Element 154 is rigidly affixed to arm 132 while element 156 is adapted to pivot about a fixed pivot pin 158. Element 156 is linked to a rod 160 connected to the piston of a hydraulic cylinder 162 by links 164 and 166. The cylinder 162 is adapted to pivot about a pin 168.

Further mounted on the length adjust crosshead 120 is means for engaging the upper end of the bore 116 of roll 106. This means comprises a bracket 170 supporting a hydraulic cylinder 172. A rod 174 connects the piston of cylinder 172 to a supporting member 176. Member 176 slidably engages guides 178 and has a plate (180, containing a hole 182, affixed thereto. Mounted on the rear of crosshead 120 is a hydraulic toggle clamp 184, shown in detail in FIGURE 9, comprising a rod 186 adapted to be driven through hole 182 when the supporting member 176 is properly positioned relative to the roll 106.

A cylindrical housing 188 is mounted on the supporting member 176. Slidably disposed within the housing 188 is a cylinder 190. Mounted on the lower end of cylinder 190 is a second cylinder 192. A tubular-member 194 extends axially through cylinders 190 and 192 and is coupled to a hollow truncated conical member 196 which is adapted to be disposed in fluid-tight engagement with the upper end of the bore 116 of the roll 106, said upper end being beveled. Member 196 is connected to a bearing member 198 adapted to rotate in cylinder 192.

Mounted on the front of housing 188 are bracket plates 200 to which a hydraulic cylinder 202 is afiixed by a pin 203. A rod 204 connects the piston of cylinder 202 to a bracket 206 affixed to a plate 208 mounted on the cylinder 190. A guide rod 210 is attached to plate 208 and depends through bearings 212 disposed in supporting member 176. Suitable means (not shown) is connected to the cylinder 202 whereby constant pressure is maintained against the roll 106 by conical member 196 during the heat treating operation.

The tubular member 194 extends through the plate 208 and bracket 206 and is connected to a rotatable joint 214 to which tubing 216 is attached. The tubing 216 is connected to a suction pump (not shown).

As shown in FIGURE 10, disposed above the coolant 14 is means for concurrently heating a first annular zone of the roll 106 and quenching a second, contiguous annular zone of said roll. Said means broadly comprises an annular heating means, e.g., an induction coil 218 disposed above an annular quenching ring 220, said heating means and quenching ring being coaxial with said roll and mounted in position by suitable brackets 221.

Mounted in recesess in one wall of the chamber 12 are bearing plates 222, upon each of which one end of an inner rail 224 and an outer rail 226 are mounted. The other ends of the rails, each of which contains a sloping section intermediate first and second horizontal sections, are mounted on bearing plates 227 disposed in recesses in the opposite wall of the chamber.

A shuttle car 228 is adapted to be driven into and out of the chamber 12 along rails 224 and 226. The car 228 is provided with forward wheels 230 which engage the outer rails 226 and rear wheels 232 which engage the inner rails 224. The inner rails are offset from the outer rails so that the body of the car is always horizontal, regardless of its position along the rails. The rear of the car 228 is connected to a rod 234 connected to the piston of a hydraulic cylinder 236.

The car 228 comprises means 238 for engaging a collar 240 disposed about the neck of the roll 106. As shown in FIGURES 11 and 12, the collar 240, which is adapted to engage a flange 241 on the neck of the roll 106, broadly comprises an annular structure 242 having an opening 244 therein through which the neck of the roll can pass. The lower portion of the structure 242 is provided with an inwardly-extending flange 246 having an offset portion upon which the roll flange 241 can be seated. The collar is also provided with a flange 250 having a pair of eyebolts 252 aflixed thereto. Disposed in the flange 250 is a spring-loaded pin 254 adapted to block the opening 244 when the flange 241 of the roll is properly seated in the collar 240.

Referring again to FIGURE 10, means 238 comprises a plate 256 having a recess 258 therein adapted to receive the collar 240. An offset 260 in plate 256 provides a shoulder upon which the flange 250 can be seated. The plate 256 is mounted on a supporting structure 262 which depends below the rails 224.

The subject apparatus operates substantially as follows. Initially, i.e. prior to the loading of a roll 106 on the carriage 90, the carriage is disposed a short distance below its uppermost position, and the length adjust crosshead is disposed in a predetermined position along the carriage 90 dependent upon the length .of the roll 106. Supporting member 176 is disposed in its retracted position, while cylinder is retracted within its housing 1'88. Pivot arm 132 is held in its raised position by toggle clamp 150, and clamping element 156 is disposed in its open position by reason of the retraction of the piston of the hydraulic cylinder 162. In addition, the shuttle car 228 is disposed in its outermost position.

The roll 106 is transported to the subject apparatus by means of a crane which engages the eyebolts 252 afiixed to the collar 240 disposed about the neck of the roll. The crane suspends the roll a short distance above the bottom center post 112.

The main drive motor 48 is energized to drive the carriage 90 upwardly until the bottom center post 112 is in fluid-tight engagement with the lower end of the bore 116 of the roll. The toggle clamp 150 is next released and the arm 132 driven about its horizontal axis until the clamping element 154 contacts the collar 240. The clamping element 156 is then driven into contact with the opposite surfaces .of the collar 240* by means of hydraulic cylinder 162.

With the roll supported on the bottom center post 112 and clamped in a vertical position, the crane is disengaged from the eyebolts 252. The supporting member 176 is then driven horizontally until the conical member 196 is axially aligned with the roll 106. The toggle clamp 184 is then actuated to cause the rod 186 to be driven through the hole 182 in the plate 180, thereby locking the supporting member 176 in position.

The cylinder 190 is next driven downwardly within its housing 188 until the conical member 196 is in fluidtight engagement with the upper end of the bore 116 of the roll. With the roll disposed between the bottom center post 112 and the conical member 196, the clamping means is returned to its retracted position. This is accomplished by driving the clamping element 156 into its open position, pivoting the arm 132 into its horizontal position, and locking the arm in said horizontal position by actuating the toggle clamp 150.

The carriage 90 is then driven downwardly until the lowest portion of the roll is within the confines of the induction coil 218. Next, the motor 110 is energized to cause rotation of the bottom center post 112, which results in rotation of the roll 106. The suction pump then is actuated to draw the coolant 14 through the holes 118 into the bore of the bottom center post 112, through the entire length of the bore 116 of the roll, and through conical member 196, tubular member 194, rotatable joint 214 and tubing 216. The coolant 14, the temperature of which is maintained between about 40 and 47 degrees F. by refrigeration means (not shown), is circulated through the entire length of the bore during the heating and quenching operation, the temperature and flow rate of said coolant being sufficient to prevent the temperature of the metal adjacent to the bore from rising above the boiling point of the coolant. During a typical heat treatment, the temperature of the metal adjacent to the bore is maintained at about 100 F. There is no substantial change in the temperature of the metal adjacent to the bore and, consequently, there are no substantial thermal stresses induced therein.

Power, e.g. 6O cycle alternating current, is then supplied to the induction coil 218 until the outer shell of the roll has reached the proper temperature, said temperature being above the upper critical temperature. The time required for the outer shell to reach the proper temperature may, for example, be three to six minutes, depending upon the circumference of the roll, the design of the induction coil, etc.

The carriage 90 is then driven downwardly at a speed of about 1.5 to 45 inches per minute. Simultaneously, the quenching ring 220 is actuated to direct a quenchant onto that portion of the roll previously heated. While this portion of the roll is being quenched, a contiguous annular zone of the roll is being heated by the induction coil 218.

After the uppermost portion of the roll has been quenched, the drive motor 48 is accelerated to rapidly cause the carriage 90, and hence the roll, to be completely submerged in the coolant 14. The position of the carriage in the coolant is such that the collar 240 is properly aligned with the collar-engaging means 238 of the shuttle car 228.

The motor is next de-energized to stop rotation of the bottom center post 112 and the roll 106. In addition, the suction pump is shut off to stop the circulation of the coolant 14 through the bore 116.

The roll 106 is then disengaged from the carriage 90 and moved laterally away therefrom to a post-quench position in the coolant 14 until the temperature throughout the body of the roll falls to below that temperature at which tempering occurs, and preferably until the temperature of the roll falls to about room temperature. To disengage the roll, the hydraulic cylinder 236 is first actuated to drive the shuttle car 228 down the rails 224 and 226 until the collar-engaging means 238 is directly below the flange 241 of the collar 240. The proper position may be ascertained by means of limit switches attached to the rails 224 and 226. Next, the carriage 90 is driven downwardly a short distance, e.g. approximately ten inches, which causes the bottom center post 112 to disengage from the bore 116 of the roll and, at the same time, causes the cylinder to be driven upwardly within its housing 188. The cylinder 190 is then driven further upwardly to bring the conical member 196 out of contact with the bore 116 and beyond the confines of the collar 240. The shuttle car 228 is then driven outwardly to the post-quench position by retracting the rod 234 of the hydraulic cylinder 236. The roll is suspended from the collar 240 while still immersed in the coolant in said post-quench position.

After the temperature of the roll 106 has fallen to about room temperature, which may take from 10 to 60 minutes, the crane engages the eyebolts 252 of the collar 240 and raises the roll a short distance, e.g. onehalf inch, to unseat the flange 250* from the collarengaging means 238. The car 228 is then driven to its outermost position and the roll raised out of the coolant 14.

Rolls heat treated in the above manner by the subject apparatus have favorable stress patterns. These favorable stress patterns are shown in FIGURE 13, in which three types of stresses induced in rolls are plotted as a function of distance from the roll exterior to the bore of the roll. Curve A shows the stresses in a roll which has been austenitized throughout the body thereof and quenched overall, including the bore. Curve B shows the stresses in a roll which has either been: (1) austenitized throughout and quenched, except for the bore; or (2) surface austenitized and quenched, except for the bore. Curve C shows the stresses in a roll which has been surface austenitized and quenched while the bore was cooled throughout the entire heat treating operation.

It is clear that, in the midwall of a roll, the maximum tensile stress of curve C does not approach the magnitude of the maximum tensile stress of curve A. Furthermore, the tensile stress level in the metal adjacent to the bore in curve C is much lower than in curve B. In each instance, the likelihood of premature failure of a roll heat treated so as to have the stress pattern of curve C is much less than in the case of rolls heat treated so as to have the stress patterns of either curves A or B.

We claim:

1. A method of heat treating a quench-hardenable ferrous metal roll having a bore therein, comprising:

(a) mounting said roll in a vertical position;

(b) progressively heating successive exterior annular zones of said roll above the upper critical temperature;

(c) progressively quenching the successively heated exterior annular zones of said roll; and

(d) during steps (b) and (c) forcing a coolant through the entire length of the bore of the roll to minimize any change in the temperature of the metal adjacent 7 S to the bore during the hardening of the exterior of to prevent the temperature of the metal adjacent to said roll. the bore from rising above the boiling point of said 2. A method as recited in claim 1, including the further coolant. step of progressively immersing the quenched zones in 4. The method as recited in claim 3, in which said a coolant and maintaining them in said coolant until the coolant comprises Water. temperature throughout the body of said roll is below 0 that at which tempering occurs. References Cited 3. A method of heat treating a quenchhardenab1e UNITED STATES PATENTS ferrous metal roll having a bore therein, comprising:

(a) mounting said roll in a vertical position; 10 2,619,439 11/1952 Renmck 148 145 (b) progressively heating successive exterior annular 2,831,789 4/1958 German 148150 zones of said roll above the upper critical tempera- 3,174,884 3/1965 Semen 148143 ture; (c) progressively quenching the successively heated RICHARD DEAN Primary Examiner exterior annular zones of said roll; and 15 U S C1 X R (d) during steps (b) and (c) forcing a coolant through the entire length of the bore of said roll, the temper- 148145, 52

ature and rate of flow of said coolant being sufficient

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