Patent Application
20190337036
The present disclosure relates to methods for processing steel coils in a cut-to-length and/or blanking line. More in particular, the disclosure is directed to a slurry blasting descaling unit that is incorporated into a cut-to-length and/or blanking line for the processing of thick gage sheet metal in coil form. The methods in the description that follows are well suited for sheet metal having a thickness in excess of 0.200 inches, and more well suited for sheet metal having a thickness in excess of 0.500 inches. In the line, the thick gage sheet metal may be uncoiled, descaled in a slurry blasting descaling unit, flattened, cut to the required length, and stacked. The end product produced by a cut-to-length and/or blanking line is a flat sheet of material cut to a precise length tolerance. The flattening may take place via a stretcher leveler or a temper mill.
The general description of a slurry blasting descaling cell is set forth in U.S. Pat. Nos. 7,601,226, 8,062,095, 8,066,549, 8,074,331, 8,128,460, 8,707,529, and 9,336,25, the disclosures all of which are incorporated by reference herein. The general description of a stretcher leveler is set forth in U.S. Pat. No. 4,751,838, which is incorporated herein by reference. The general description of a temper mill is set forth in U.S. Pat. No. 3,292,402, which is incorporated herein by reference.
As described in more detail, the disclosure is directed to a processing line with an uncoiler followed by a slurry blast descaling unit followed by either a temper mill or a stretcher leveler, following by a shearer, following by a stacking apparatus. The slurry blast descaling cell may be operated intermittently and synchronized with the operation of the stretcher leveler and shearer, or the temper mill and the shearer, as applicable. Thus, the sheet metal coil may be intermittently uncoiled from the unwinder and intermittently descaled as it is advanced through the slurry blast descaling cell in a manner that matches the cycle time of the shearer and stretcher leveler, or temper mill and the shearer.
A first exemplary cut-to-length and/or blanking line 20 is shown generally in
As shown best in
As shown best in
As shown in
As shown in
The processing line may be configured to operate in an advancement mode and an idle mode. In the advancement mode, the uncoiler 22, the descaler 30, and the stretcher leveler 32 may be operated to advance the sheet metal through the line by uncoiling the coil of sheet metal 24 in the uncoiler, directing the sheet metal through the descaler and to the stretcher leveler, and advancing the portion of sheet metal stretched in the stretcher leveler toward the shearer 34 and stacking apparatus 36. In the advancement mode, the sheet metal 24 may be descaled in the descaler 30, and stretch leveled in the stretcher leveler 32. In the idle mode, the uncoiler 22, the descaler 30, and the stretcher leveler 32 may be operated to stop the advancement of the sheet metal from the uncoiler through the descaler, and to stretch the portion of the sheet metal positioned in the stretcher leveler. During the idle mode, the descaling of the sheet metal 24 in the descaler 30 may be stopped or significantly reduced. Also, during the idle mode, the desired length of the sheet metal 24 may be cut to length by operating the shearer 34 to cut to length the sheet metal advanced past the shearer. The stacking apparatus 36 may then stack the lengths of sheet metal cut to the desired length and place them on the exit conveyor 38.
Operation of the shearer 34 to cut to length the sheet metal advanced past the shearer may occur during the transition of the line from the advancement mode to the idle mode. At the end of the advancement mode, when the portion of the sheet metal 24 to be stretched in the stretcher leveler 32 is positioned in the stretcher leveler before stretching occurs but after the sheet metal is clamped in the stretcher leveler, the shearer 34 may be operated to cut to length the desired length of sheet metal. Once cut, the portion of the sheet metal positioned in the stretcher leveler 32 may then be stretched. Once stretched, the stretched portion of the sheet metal may be unclamped. The processing line may then be transitioned, switching from operation in the idle mode to operation in the advancement mode by again advancing the sheet metal 24 from the uncoiler 22 through the descaler 30 to the stretcher leveler 32, and descaling the sheet metal in the descaler. The steps of operating in the advancement mode followed by operating in the idle mode followed by operating in the advancement mode may be continued until an end of the sheet metal 24 arrives at the stretcher leveler or there is otherwise insufficient length of the sheet metal to process and advance through the line.
Referring to
As shown in
As best shown in
In one aspect of operating the descaler 30 in the idle mode to stop and/or reduce descaling of the sheet, the valves 80 which supply grit to the eductor may be shut so that grit is not mixed with the liquid to form the slurry for descaling. Thus, the eductor feed pumps 72 may continue to delivery liquid to eductors 80 and to the impellers 50, but because no grit is entrained in the liquid to the form the slurry, effective descaling does not occur. In the alternative or in addition to the aforementioned aspect of operation in the idle mode, all or a majority the discharge of the eductor feed pumps 72 may be recirculated to any one or more of the slurry settling, cleaning, or supply tanks 74,75,76 (or the suction side of the eductor feed pump) rather than being directed to the eductors, thereby decreasing pressure supplied to the eductors 80 and decreasing drawing and mixing of grit with liquid to form the slurry and delivery slurry to the nozzles 62 of the impellers 50. Thus, the eductor feed pumps 72 may continue to operate at rated speed but because at least a majority of the liquid is recirculated rather than delivered to the eductors, the supply of slurry to the manifold and the impellers is effectively suspended and effective descaling does not occur. In the alternative or in addition to the aforementioned aspect of operation in the idle mode, the nozzle 62 may be selectively adjusted to decrease the blast pattern to a level where descaling of the sheet does not occur. For instance, in the advancement mode for descaling of the sheet metal, the nozzle 62 may be rotated with the actuator 68 into position to provide slurry to the vanes 66 of the impeller in a manner that provides an effective amount of the slurry to the impeller and allows the impeller to propel the slurry against the sheet metal for descaling. In the idle mode when descaling of the sheet metal is stopped or reduced, the nozzle 62 may be rotated by the actuator 68 into position so as to disrupt the supply of the slurry to the vanes of the impeller. Thus, in the idle mode, the impeller wheels 50 may be continue to rotate, for instance, at rated speed or a reduced speed, but because the nozzle 62 has been positioned to disrupt the delivery of an effective supply of slurry to the wheels (e.g., an insufficient supply or no supply), descaling or a desired amount of descaling does not occur. Once the advancement mode resumes, the nozzle 62 may be rotated to supply the slurry to the impeller wheel and allow the impeller to propel the slurry against the sheet with a desired intensity of the blast pattern for descaling.
In addition or in the alternative to aforementioned aspects of operating the descaler in the idle mode, the impeller wheels 50 may be adjustably positioned toward and away from the surface of the sheet metal passing through the descaler. The impeller wheels 50 and their respective driving motors 52 may be adjustably positioned about axes that are perpendicular to the axes of rotation of the impellers to adjust the angle and/or the distance of the slurry 60 impact with the surface of the sheet metal 24. Thus, the impeller wheels 50 may be adjustable to vary the angle of the slurry blast projected toward the surface of the strip from directly down at the strip surface to an obtuse angle, thereby effectively stopping or reducing descaling of the strip.
In addition or in the alternative to the aforementioned aspects of operating the descaler 30 in the idle mode, the motors 52 associated with the impeller wheels 50 may be operated in a manner to vary the rotation of the impel wheels to effectively stop or reduce descaling of the sheet metal. For instance, hydraulic motors may be used to drive the impeller wheels 50, and the source of hydraulic fluid for driving the motors may be recirculated to effectively idle the motors during the idle mode. As another example, the motors 52 may comprise electric motors and the electric motors may have variable frequency drives, thus allowing for changing of the speed of the motors without start and restart of the motors. In the advancement mode, the impeller wheels 50 may rotate to generate a slurry discharge velocity in a range of about 100 feet per second to 200 feet per second (or more preferably, in a range of about 130 feet per second to 150 feet per second). In the idle mode, the impeller wheels may rotate to generate a slurry discharge velocity below 100 feet per second.
A cut-to-length processing line with the stretcher leveler 32 tends to produce flat, continuous lengths of sheet metal 24 that have no residual stresses and tend to maintain shape over time. Stretcher leveling operations generally have minimal effect on the physical and mechanical properties of the continuous length of sheet metal.
A second exemplary cut-to-length and/or blanking line 100 is shown generally in
In a manner similar to that described above, the processing line 100 may be operated in the advancement mode and the idle mode. Using one or more of the aforementioned methods, the descaler 30 may be operated in the advancement mode and idle mode to descale the sheet metal 24 as it is advanced and to stop descaling temporarily for the shearer 36 to cut the sheet metal to desired length. The heavy gauge temper mill 100 may be operated to flatten the sheet metal in the advancement mode and to temporarily stop flattening in the idle mode to allow for the shearer to cut the sheet metal to the desired length. For instance, in the advancement mode, a desired length of the sheet metal 24 may be unwound from the unwinder 22, advanced through the descaler 30 and descaled, advanced through the heavy gauge temper mill 100 and flattened, and passed through the shearer 36. Then, the line may be transitioned from the advancement mode to the idle mode to allow the shearing operation to occur. Once the shearing operation is complete, the line may be transitioned from the idle mode to the advancement mode with uncoiling the sheet metal from the unwinder 22, descaling the sheet in the descaler 30, flattening the sheet in the heavy gauge temper mill 100 and passing the desired length through the shearer 36. The line may be operated alternating between the advancement mode and the idle mode until there is an insufficient desired length of the sheet to passed through the shearer 36. If the shearer 36 is a rotary shear rather than a direct drive shear, the time during which the line 100 is in the idle mode may be reduced.
In both line configurations 20,100 described above, the line may be placed in the idle mode when a coil runs out and a new one is threaded through the line. The line may be in the idle mode until the head of the new coil enters the descaler 30. The line may be transitioned to the advancement mode.
As shown in view of the foregoing, it will be seen that the several advantages of the invention are achieved and attained. The embodiments were chosen and described in order to best explain the principles of the disclosure and their practical application to thereby enable others skilled in the art to best utilize the principles in various embodiments and with various modifications as are suited to the particular use contemplated. As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.
