US3373591A - Fluid control system for a rolling mill - Google Patents

Description

March 19, 1968 J, w, o' ET AL 3,373,591

FLUID CONTROL SYSTEM FOR A ROLLING MILL Filed Aug. '9. 1965 3 Sheets-Sheet 1 INVENTOR. JEREMIAH W. O'BRIEN FRANK J. GLEVE ORT FIG. I BY BERT J. LA

THEIR'{TTORNEY J. w. OB'RIE'N ET AL 3,373,591

March 19, 1968 FLUID CONTROL SYSTEM FDR A ROLLING MILL 3 Sheets-Sheet 2 Filed Aug. 9, 1965 INVENTOR. JEREMIAH w. O'BRIEN FRANK a. suave BERT J. ;2APORT F 315% RNEY March 19, 1968 w, O'BRIEN ET AL 3,373,591

FLUID CONTROL SYSTEM FOR A ROLLING MILL- 3 Sheets-Sheet 3 Filed Aug. 9, 1965 FIG. 4

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INVENTOR- JEREMIAH W. O'BRIEN FRANK J. GLEVE BERT J. LAMPORT BY t THEIR ATTO' sv FIG.5

FLUID CONTROL SYSTEM FUR A ROLLDJG MILL Jeremiah Wagner QBrien, Frank .i'oseph Gleve, and Bert J. Lamport, Pittsburgh, Pa, assignors to United Engineering and Foundry Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Aug. 9, 1965, Ser. No. 478,354 7 Ctaims. (Cl. 72-245) ABSTRAT OF THE DESCLGSURE In a rolling mill having piston cylinder assemblies for imposing a bending moment on at least one of the rolls to deflect the roll and thereby to change its crown, a fluid control system adapted to rapidly decompress the pressure in the cylinder employed to bend the roll so that the roll may be positioned by the screwdown of the mill and wherein the screvvdown will not have to work against the roll bending force. The fluid control system comprises an intensifier, the high pressure side of which is connected to the piston cylinder assemblies to which side is also associated a decompression valve for selectively decompressing the high pressure. The low pressure side of the intensifier is fed from a second supply circuit.

This invention relates to a fluid control system and, more particularly, to such a system employed in conjunction with a rolling mill having a force exerting means operating under high pressure.

While not necessarily limited to such use, the present invention will be described as applied to a rolling mill having means for applying a bending force on one or more rolls to control the crown of the roll or rolls. By crown is meant the axial contour of the roll along that portion which is in engagement with an adjacent roll or the material being rolled in order to obtain a substantial constant transverse thickness.

'4-high mill. Since controlling the crown of the backup rolls requires a greater bending force, this type of crown control for a rolling mill will be used to describe the invention, although the invention may be employed with equal success in a rolling mill having work roll crown control as well as in other machines requiring a release or decompression of a high pressure.

While prior to this invention it had not been considered feasible, it was nevertheless recognized as highly desirable to incorporate the backup crown control feature in a rolling mill wherein the upper working roll must be separated a considerable distance from the lower working roll after completion of the rolling operation of each workpiece. The reasons for the unfeasibility was due to the fact that the screwdown mechanism had to have suflicient power to raise the rolls against the bending pressure applied to the rolls, otherwise auxiliary means would have to be provided to resist the bending force that would otherwise be imposed on the screws of the screwdowns. An arrangement of such auxiliary means is illustrated in the aforementioned US. Patent No. 3,171,305. While the use of reaction piston cylinder assemblies is desirable in certain mills, other rolling mills having a large roll gap opening required reaction piston cylinder assemblies pos- States atent C) sessing large strokes, whereby such an arrangement becomes impractical. Furthermore, in a rolling mill which did not require the closing of the roll gap under the rolling loads, it was diflicult to justify the substantial additional expense of providing increased screwdown capacity that would be required to move the screws against the roll bending pressure.

A third approach to the problem would be to interrupt the application of roll bending pressure so that the rolls could be quickly adjusted by a low capacity screwdown. In this solution, which in many cases has been found to be the only practical approach, additional difiiculties are involved in that any decompression of the pressure must be accomplished not only rapidly to avoid losses in productivity but in a manner to assure that shook forces generated by the quick release of pressure will not cause damage to the mill equipment or the components of the pressure generating system.

The present invention provides a fluid control system for a rolling mill having a high pressure exerting system employed, for example, to control the crown of the rolls or as a screwdown, wherein the high pressure system can be rapidly decompressed in a manner that shock forces incident thereto will be minimized, thus avoiding damage to parts of the system or mill.

It is another object of the present invention to provide in a rolling mill, which includes a fluid force-exerting means for applying a high pressure to at least one roll thereof, a fluid control system for said force-exerting means, including a first fluid circuit consisting of a fluid high-pressure generating means, and a second fluid circuit connected to said first circuit and including means adapted to eflfect a reduction in the high pressure whenever said high pressure is not to be applied to the roll.

It is a still further object of the present invention to provide in a rolling mill, including a fluid force-exerting means for applying a bending force on at least one roll of the mill, a fluid control system for said force-exerting means, including a first fluid circuit including a fluid highpressure generating means having a low pressure side and a high pressure side, said first fluid circuit supplying fluid to said high pressure side of said pressure generating means including means adapted to effect a reduction in the high pressure whenever said high pressure is not to be applied to the roll, the fluid in said first circuit being conducive to the environment of the rolling mill; and a second fluid circuit for supplying a fluid to the low pressure side of said generating means. If desired, the fluid control system may include a third fluid circuit associated with said first circuit including means to supply fluid under a prefill pressure to said force-exerting means to avoid depletion of fluid in said fluid force-exerting means when the high pressure is not being imposed.

A further object of the present invention is to provide in a rolling mill, a plurality of piston cylinder assemblies for applying a bending force to at least two rolls of the mill, a fluid control system for said piston cylinder assemblies including a fluid pressure intensifier having its high pressure side connected to said piston cylinder assemblies, a decompression valve located between said high pressure side of said intensifier and said piston cylinder assemblies, means for operating said valve whereby, when open, the high pressure fluid is allowed to escape from the piston cylinder assemblies and, when closed, the high pressure fluid is trapped between the intensifier and said valve, means for delivering a fluid under constant pressure to the low pressure side of said intensifier and means associated with said valve to deliver fluid under a prefill pressure to said piston cylinder assemblies when said high pressure fluid is not being applied, thereby to avoid depletion of fluid in the cylinders, said last-named means being effective only when said valve is opened.

It is still another object of the present invention to provide a multiple plunger feed pump in place of the aforementioned control systems having intensifier means. Such a pump maintains the fluid control system pressurized should leakage occur which would otherwise result in the loss of pressure and, hence, roll contour control.

These objects, as well as various other features and advantages, of the present invention will be more fully appreciated when the following description is read in conjunction with the accompanying drawings of which:

FIGURE 1 is an elevational view of a i-high rolling mill having backup roll crown control;

FIGURE 2 is a partial plan view of the rolling mill illustrated in FIGURE 1;

FIGURE 3 is a schematic diagram of one form of a fluid control system incorporating the features of the present invention;

FIGURE 4 is a schematic diagram of second form of a fluid control system of the present invention; and

FIGURE 5 is a schematic diagram of a third form of the present invention.

With reference now to FIGURE 1 there is illustrated a 4-high rolling mill having two spaced-apart housings 11, only one of which is shown in the drawings, formed with a window 12 into which there is received upper and lower work rolls 13 and 14 that are supported by upper and lower backup rolls 15 and 16, respectively. The work rolls are provided in a customary manner with bearing- chock assemblies 17 and 18; while the backup rolls 15 and 16 have bearing-chock assemblies 19 and 21 A conventional screwclown mechanism, including a pair of screws, one of which is only shown at 22, is employed to adjust the upper work roll 13 and backup roll 15 relative to the lower work roll 14.

With reference now to FIGURES l and 2 and, particularly, to the backup roll crown control apparatus, the backup rolls 15 and 16 are provided with outward extending neck portions in accordance with known practice, onto which there is positioned outboard bearing-chock assemblies 2 3 and 24, respectively. Positioned between these bearing chocks are two roll bending piston cylinder assemblies 25 and 26 which include upper pistons 27 and 28, lower pistons 29 and 31, and cylinders 32 and 33; it being appreciated that while not shown in FIGURES 1 and 2, FIGURES 3, 4 and 5 illustrate schematically the roll bending piston cylinder assemblies for the opposite end of the backup rolls. These cylinder assemblies include upper pistons 27a, 28a, lower pistons 29a, 31a and cylinders 32a and 33a.

To facilitate changing of the work rolls 13 and 14 or the backup rolls 1 5. and 1d, the roll bending piston cylinder assemblies are mounted in a manner to be quickly positioned remote from the housing window 12. This is accomplished by attaching brackets 34 and 35 to the cylinders 32 and 33, respectively. These brackets are, in turn, rigidly secured to shafts 36 and 37 which are pivotally carried by the housing 11 through brackets 38 and 39. Connected to the lower ends of the shafts are piston cylinder assemblies 41 and 42, which upon operation rotate the shafts 36 and 37 to swing the roll bending piston cylinder assemblies away from the housing window to a position where they will not interfere with removal of the rolls.

With reference again to the roll bending piston cylinder assemblies 25- and 26, it will be noted that, as illustrated in FIGURES 1 and 2, they are connected to fluid supply lines 43 and 44. These supply lines are connected together to form a common line at the upper portion of the mill housing. Similar supply lines 43a and 44a are provided for the roll bending piston cylinder assemblies 25a and 26a for the opposite end of the backup rolls. Thesesupply lines are also connected to the line 45 which communicates with all four roll bending cylinder assemblies 25, 26, 25a and 26a, simultaneously.

Connected to the supply line 45 is a roll bending fluid control system, three separate forms of which are illustrated schematically in FIGURES 3, 4 and 5. Before describing these control systems, it is believed noteworthy to point out certain operational aspects of the rolling mill just described. If, by way of an example, the mill is to be employed as a reversing breakdown mill, it is a common practice to separate the work rolls 13 and 14 a predetermined distance by employing the screwdown mechanism. The workpiece is then passed through the mill and reduced in thickness, after which the screwdown is again actuated and the upper work roll 13 is positioned closer to the lower work roll 14 following which the workpiece is again passed through the mill and further reduced. This process then continues until the workpiece is reduced to the desired thickness after which it is transferred to other rolling mills or processing apparatus. It should be particularly pointed out that as the upper work roll '13 is lowered toward the lower work roll 14, the upper backup roll 15 is also lowered a corresponding amount toward the lower work roll 14. This necessitates that the pistons 27, 28 and 27a and 23a retract into their respective cylinders 32, 33, 32a and 33a. Such a displacement of the pistons into the cylinders is in opposition to any fluid pressure in the line 45. Conversely, unless the fluid pressure is interrupted or reduced when the screws of the mill are retracted to permit raising of the upper backup roll 15 and the work roll 13, the screws must operate against the pressure exerted by the roll bending cylinder assemblies.

The three control systems shown in FIGURES 3, 4 and 5, while designed to obtain the same result, namely the effective decompression of the fluid in the roll bending piston cylinder assemblies to allow the roll to be reset, differ substantially in the selection of components. This difference is due to the types of fluids employed. For example, in FIGURE 4, which is the simplest of the three systems, oil is employed throughout the system. While oil, because of its existent advantages, is preferred in certain mill applications, it creates a fire hazard and in addition, upon leakage, marks the workpiece so that an oil system is not desirable. These objections, to a certain extent, can be avoided by a system designed to use both oil and water as exemplified in FIGURE 3, in which the water is used in a separate system that feeds the mill and the oil is used in a second system located away from the mill. If, however, the system of FIGURE 3 is not satisfactory then an all-water system can be employed as illustrated in FIGURE 5.

With reference first to the roll bending fluid control system illustrated schematically in FIGURE 3, which, as noted, is an oil and water system, it will be noted that to the line 45 there is connected the high pressure end of an intensifier 46. The low pressure end of this intensifier is connected by a line 47 to a three-way valve 48 which is operated by solenoid pilot unit 43a. A drain line 49 is provided for the valve that runs to a reservoir 57. A line 51 from the valve 48 is connected to a servo-controlled pump 52 that delivers fluid at a variable volume and pressure. Such a pump is readily available in the industry and may be of the type described in Bulletin No. P-4-5-E, Dennison Hydraulic Pumps, Series 600, 700, 800; Dennison Engineering Division, American Brake Shoe Company. Associated with the pump 52 is a constant pressure pilot pump 53 connected by a line 54 to the pilot unit 48a. A line 55 supplies fluid to the pumps 52 and 53 from a booster pump 56. The pump 56 is in turn connected to the supply reservoir 57 by a line 58. The various elements thus far described with respect to FIGURE 3 are employed to deliver a high pressure to the line 45 and hence, to the piston cylinder assemblies 25, 25a, 26 and 26a to bend the backup rolls 15 and 16. In operation, the pump 56 delivers fluid from the reservoir 57 to the servo.

controlled pump 52. The pump 52 delivers fluid under variable pressure through the valve 48 to the intensifier 46, where the pressure is increased and delivered to the roll bending piston cylinder assemblies by the line 45. It being appreciated that the pressure in the roll bending piston cylinder assemblies and, hence, the degree of roll contour, is variable at will by operating the servo of the pump 52 to thereby control the transverse thickness of the material being rolled.

To effect a decompression of the very high pressure required to bend the roll, the line 45 is connected by a line 59 to a pilot-operated check valve 61 which is employed in a dual capacity as a preflll and decompression valve, an example of such a valve being shown in High Pressure Hydraulic Companys Catalog No. C4106 entitled, Check Valves, page 5, model VPPS631052. This valve has a solenoid pilot unit 62 connected to the constant pressure pilot line 54 of the pilot pump 53. The valve 61 has a line 63 connected to a three-way valve 64- which is in turn connected to a surge tank 65 by a line 66. Also connected to the three-Way valve 64 is a back-pressure regulator valve 67 that has a drain line 68 connected to a supply reservoir 69. Fluid pressure is delivered to the surge tank 65 through a fluid supply line 70 having a pump pressure regulator valve 71 which is fed from a prefill pump 72. This pump is in turn connected by a line 73 to the reservoir 69. The surge tank 65 being of conventional design has an air compressor 74 connected by a line 74a to the surge tank whereby a substantially constant fluid pressure is delivered to the line 63.

When it is desired to decompress the high pressure required to bend the rolls and prior to the actual decompression, the solenoid of the pilot unit 48a is actuated to open lines 51 and 47 to the drain line 4-9, thereby unload m the pump 52 and draining the fluid from the low pressure end of the intensifier 46. At the same time, the solenoid of the pilot unit 62 is actuated to allow the pressure in the pilot line 54- to be applied to the pilot-operated check and decompression valve 61. This allows the high pressure in the line 45 to be quickly reduced by discharging fluid through the line 63 and through the threeway valve 64- into the surge tank 65. The pressure in the line 53 can be maintained at any predetermined low value by adjusting the pump pressure regulator valve 71 such as may be required when adjusting the rolling mill rolls as previously described. At a low pressure setting of the valve 71 the lines of the entire control system are maintained prefilled and at a sufficient pressure to keep the cylinder of the roll bending piston cylinder assemblies 25, a, 26 and 26a filled with fluid while roll adjustment takes place.

It is important to note that when the work rolls I3 and 14 or backup rolls 15 and 16 are to be changed, the roll bending piston cylinder assemblies are remotely positioned as previously described. When this occurs, virtually no resistance is aflorded by the pistons 27, 28, 29 and 31 and there is the danger that the pistons will be displaced out of their respective cylinders. To overcome this, according to the present invention, the three-way valve 64 is positioned to open line 63 to line 6? and valve 67 is adjusted to that a relatively low pressure exists in the line 63 and hence, the line 45. This pressure will still maintain the fluid control system prefilled, but at a pressure that will not extend the roll pistons oi the piston cylinder assemblies, as noted previously. It is a feature of the control system illustrated in FIGURE 3 to employ two separate fluid systems, whereby the fluid in each system may be advantageously selected. In this respect, it is desirable to select a fluid such as a rolling solution for the reservoir 69 which is used in the lines to the piston cylinder assemblies. In this manner, should leakage occur in the lines closely associated with the rolling mill, a potential fire hazard is eliminated as Well in certain cases as the possibility of staining the workpiece being rolled. Oil can be used for the reservoir 57, thereby still affording the advantages inherent in its use.

With reference now to the fluid control system illustrated in FIGURE 4, a line 75 interconnects the line 45 of the roll bending piston cylinder assemblies 25, 25a, 26 and 26a and a high pressure servo-controlled pump 76 which may be the same type as the pump 52. A feed line 77 for the pump 76 is connected to a prefill tank 78 which delivers a substantially constant pressure to the line 77 by employing an air compressor 79 connected to the tank by a line 81. In the operation of this system, the low pressure fluid is delivered to the pump 76 which in turn delivers high pressure fluid to the line 45 and hence, to the roll bending piston cylinder assemblies. The magnitude of fluid pressure is varied by the servo mechanism of the pump 76, whereby the desired roll bending pressure is ap plied to the backup rolls l5 and 16. It will be noted that the control system of FIGURE 4 further comprises a pilotoperated decompression check valve 82 connected to the line 75 similar in operation and construction to the valve 61 of FIGURE 3. The valve 82 is in turn connected to the prefill tank 78 by a line 83 having a pressure control valve 84.

Decompression of the control systems illustrated in FIGURE 4 is essentially as follows. The decompression check valve 82, normally closed to eflect bending of the backup rolls l5 and 16, is controlled by operating the solenoid shown associated with it. This in turn actuates the fluid pressure check mechanism of the valve 82 which quickly lowers the pressure by discharging fluid into the line 83. After the pressure in the lines 45 and 75 has been reduced the valve automatically opens to permit free passage of the fluid through the valve and into the prefill tank 78, it being appreciated that the pump 76 continues to operate and that the setting of the pressure control valve 84 determines the pressure in the line 75 and hence, line 45 and in the piston cylinder assemblies 27, 28, 27a and 23a. This control system is thereby maintained prefilled at a pressure determined by the valve 84 so that adjustment of the backup rolls can be effected without overloading the screwdown mechanism. Further adjustment of the valve "84 reduces the pressure in the roll bending piston cylinder assemblies so that they can be remotely positioned, as previously described, without adverse eflects to facilitate changing of the rolls.

FIGURE 5 illustrates a schematic diagram of a third form of roll bending fluid control system in which a line 85 interconnects the line 45 of the roll bending piston cylinder assemblies with the high pressure end of an intensifier 86. A line 87 interconnects the low pressure input end of the intensifier with a three-way solenoid operated valve 88 which has a drain line 89 communicating with a supply tank 91. A line 92 having a pressure control valve 93 connects the valve 88 with a pressurized surge tank 94 which has an air supply line 95 connected to an air compressor 96. The surge tank 94 is supplied with fluid from a pump 97 through a line 98 from a tank 91. In the line 98 there is provided a pump pressure regulator valve 97a which assures that a substantially constant fluid pressure is delivered to the surge tank.

In the operation of the control system illustrated in FIGURE 5 to effect bending of the backup rolls 15 and 16, the pump delivers fluid to the surge tank 94 which in turn delivers fluid through the line 92 at a substantially constant pressure to the pressure regulator valve 93 which is employed to vary the fluid pressure applied to the low pressure end of the intensifier 86. The pressure is then intensified and delivered by the line 85 to the line 45 of the roll bending piston cylinder assemblies 2'7, 28, 27a and 28a. Thus, by varying the adjustment of the valve 93, the roll bending pressure is also varied.

The control system illustrated in FIGURE 5 further includes a pilot-operated decompression check valve 99 similar to the valves 61 and 82 and which is connected to the line 85. A line ltll interconnects the valve 99 with a pressure control valve 102 and a dual range backpressure control valve 103 that in turn communicates with the tank 91. The pressure control valve 102 is connected to the line 92. The pilot operated check valve 99 is connected by a pilot line 105 to a solenoid operated pilot 1% which has a fluid pressure line 107 from the surge tank 94.

When it is desired to decompress the fluid of the system illustrated in FIGURE 5 whenever the roll gap is to be opened or the rolls replaced, the solenoid as-- sociated with the three-way valve 88 is operated to close the valve. This blocks fluid passage from the line 92 and connects the line 8'7 with the line 89 to drain the fluid from the low pressure end of the intensifier 86. As the pressure in the line 85 is reduced, it drops below the pressure exerted in the line 1E5 on the pilot-operated check valve 99. When this occurs, the valve 99 automatically opens and the line 85 communicates with the line 101. The pressure in this line is controlled by the pressure control valve 102 by which a nominal pressure is set and the control system maintained prefilled during adjustment of the rolls. When it is desired to change the mill rolls, the pressure in the line 45 is further reduced by adjusting the back dual range pressure valve 103 so that a relatively low pressure is maintained in the roll bending piston cylinder assemblies such as required when no resistance is afiorded the pistons of the roll bending cylinders during the changing of the rolling; mill rolls.

With reference again to the control system illustrated in FIGURES 3 and 5, it is to be pointed out that according to the present invention a multiple plunger boiler feed pump can be employed in place of the intensifiers 46 and 86. Such a pump is readily available in the trade and may be any one of the types illustrated in Bulletin No. 86, Fifth edition of the Union Stearn Pump Company, Battle Creek, Mich. The employment of such a pump has the advantages that should leakage occur in the high pressure part of these systems, the multiple plunger feed pump Will keep the system charged by repeatedly overlapping strokes, thereby preventing the loss of roll contour control.

In accordance with the provisions of the patent statutes, we have explained the principle and operation of our invention and have illustrated and described what we consider to represent the best embodiments thereof. However, we desire to have it understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

I. In a rolling mill including a fluid force exerting means for appling a bending force on at least one roll of the mill to compensate for roll deflection,

a fluid control system for said force-exerting means, including a first high pressure fluid circuit including a fluid pressure generating means connected to said force exerting means for applying high pressure to said one roll, said pressure generating means having a low pressure side and a high pressure side,

said first fluid circuit including means for supplying 60 fluid to said high pressure side of said pressure generating means, and means etlective to reduce the high pressure whenever said high pressure is not to be applied to said roll; and

a second fluid circuit for supplying fluid to the low pressure side of said pressure generating means.

2. In a rolling mill according to claim 1 in which said first fluid circuit includes a means for supplying fluid under a preflll pressure to said force-exerting means to avoid depletion of fluid in said force-exerting means when the high pressure is not being imposed.

3. In a rolling mill having a plurality of piston cylin der assemblies for applying a bending force to at least two rolls of the mill to compensate for roll deflecton,

a fluid control system for said piston cylinder assemblies including a fluid pressure intensifier having its high pressure side connected to said piston cylinder assemblies,

a decompression valve located in a line running be tween said high pressure side of said intensifier and said piston cylinder assemblies,

means for operating said valve whereby, when open, the high pressure fluid is allowed to escape from the piston cylinder assemblies and, when closed, the high pressure fluid is trapped between the intensifier and said valve,

means for delivering a fluid under variable pressure to the low pressure side of said intensifier, and

. means associated with said valve to deliver fluid under a prefill pressure to said piston cylinder assemblies when said high pressure fluid is not being applied, thereby to avoid depletion of fluid in the cylinders, said last-named means being eliective only when said valve is opened.

4. In a rolling mill according to claim 3 in which said decompression valve comprises a pilot-operated check valve having a first output connected to said piston cylinder assemblies and a second output connected to a supply reservoir, and

having an input connected to said means for delivering a fluid under a prefill pressure.

5. In a rolling mill according to claim 3, wherein said means for delivering a fluid under a prefill pressure includes a valve and means for varying the output of this valve to vary the pressure of the prefill fluid.

6. In a rolling mill according to claim 3 including a pressurized surge tank for supplying fluid under pressure to said low side of said intensifier and decompression valve, and

a pump for supplying fluid to said tank.

7. In a rolling mill according to claim 6, including a three-way valve having a first outlet connected to said intensifier, and

a second outlet connected to a supply reservoir and an outlet connected to said surge tank.

References Cited UNITED STATES PATENTS 2,430,410 11/1947 Pauls 72-245 3,280,610 10/1966 Qualey 72245 FOREIGN PATENTS 647,606 12/ 1950 Great Britain.

CHARLES W. LANHAM, Primary Examiner.

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