Claims
- 1. Continuous rolling mill including: a plurality of roll stands arranged in series, each of said roll stands comprising a frame, at least a pair of work rolls, roll chock means for supporting respectively said work rolls, one of said work chock means being mounted on the frame for movement together with the corresponding roll in a direction perpendicular to the axis of said roll, and means for adjusting the position of said movably mounted chock means to thereby set the gap between the associated work roll and the opposite work roll at a desired value; and force measuring means provided in at least one of the roll stands for measuring a force in a workpiece extending between said one roll stand and an adjacent one of the roll stands, said force measuring means comprising means for mounting at least one of said work roll chock means on the frame for movement within a limited extent in a direction parallel to the direction of the path of the workpiece, load sensing rod means extending in a direction substantially parallel to the direction of the path of the workpiece and adapted to contact at one end with said chock means movable in the direction parallel to the direction of the path of the workpiece, transducer means positioned outside of the frame of said one roll stand and associated with said load sensing rod means so as to receive a force axially transmitted through said rod means for providing an electric signal representing the force, means for effecting axial movement of said rod means together with said transducer means into and out of contact with the movable roll chock means, and hydraulic means for supporting said rod means under a predetermined hydraulic pressure so that when a load exceeds said predetermined pressure said rod means is shifted to prevent such excessive load from being applied to said transducer means.
- 2. Rolling mill in accordance with claim 1 wherein said sensng rod means extends through a hole formed in the frame of said one roll stand to contact at one end with said chock means movable in the direction parallel to the direction of the path of the workpiece.
- 3. Rolling mill in accordance with claim 1 wherein said sensing rod means extends over the outside of the frame of said one roll stand opposite to the path line of the workpiece.
- 4. Rolling mill in accordance with claim 1 wherein said hydraulic means includes hydraulic cylinder means and piston means disposed in said cylinder means, said piston means being connected with said load sensing rod means, said cylinder means being axially slidably received in casing means which is adapted to be driven by said axial movement means, said transducer means being disposed in said casing means so as to receive a pressure through said hydraulic cylinder means from said load sensing means.
- 5. Rolling mill in accordance with claim 1 wherein said hydraulic means includes hydraulic cylinder means and piston means disposed in said cylinder means, means being provided for connecting said piston means and said load sensing rod means with said transducer means interposed therebetween, said axial movement means being in engagement with said hydraulic cylinder means.
- 6. Rolling mill in accordance with claim 5 wherein said axial movement means includes a rotatable member disposed around the hydraulic cylinder means and in screw engagement therewith, and means for rotating said rotatable member.
- 7. Rolling mill in accordance with claim 1 wherein at least one of said roll stands is of the horizontal type which comprises a frame, upper and lower rolls, upper and lower chock means for supporting respectively the upper and lower rolls, said upper chock means being mounted on the frame for vertical movement together with said upper roll, and said roll gap setting means abutting against the upper chock means and withstanding the force tending to move the upper roll and the upper chock means upwardly.
- 8. Rolling mill in accordance with claim 7 wherein said upper roll chock means is mounted for swinging movement about a point above an axis of the upper roll to provide said movement parallel to the path of the workpiece, and said roll gap setting means including a thrust member which makes point contact with said roll chock means substantially at said point.
- 9. Rolling mill in accordance with claim 8 wherein said upper roll chock means is mounted by self-contering bearing means which allows said swinging movement.
- 10. Rolling mill in accordance with claim 8 wherein said thrust member has a part-spherical lower end which engages with a part-spherical seat on the upper roll chock means, the part-spherical configuration of said seat having a radius of curvature greater than that of the lower end of the thrust member.
- 11. Rolling mill in accordance with claim 1 wherein said one roll chock means is located in the frame with clearances at the forward and rearward sides thereof and mounted on the frame through means adapted to constrain the movement in the axis direction of the work roll but to allow the movement parallel to the path of the workpiece.
- 12. Rolling mill in accordance with claim 11 wherein said means for constraining the movement in the axis direction but allowing the movement parallel to the path of the workpiece is a laminated composite comprising a plurality of alternate metal and plastic laminae.
- 13. Rolling mill in accordance with claim 1 wherein at least one of said roll stands is of the vertical type which comprises upper and lower frames, drive side and work side vertical work rolls, and roll chock means for supporting said drive side and work side work rolls, respectively, said work side roll chock means being mounted on said frames to be movable within a limited extent in the direction parallel to the direction of the path of the workpiece, said force measuring means being mounted on one of said frames in such a manner that the load sensing rod means thereof can be brought at one end into contact with said work side roll chock means.
- 14. Load sensing device for measurement of a force in a workpiece extending between adjacent two roll stands each of which includes a frame, at least a pair of work rolls and work roll chocks for supporting the work rolls respectively, comprising a housing adapted to be mounted on the frame of one of the adjacent two roll stand, load sensing rod means having one end adapted to be contacted with one of the work roll chocks of said one roll stand, transducer means associated with said load sensing rod means so as to receive a force axially transmitted through said rod means for generating an electric signal representing the force, means for effecting axial movement of said rod means into and out of contact with said one work roll, and hydraulic means including hydraulic cylinder means and piston means disposed in said cylinder means, said piston means being adapted to support said rod means under a predetermined hydraulic pressure so that when a force acting on through said rod means exceeds said predetermined pressure, said piston moves to prevent such an excessive force from being applied to said transducer means.
- 15. Load sensing device in accordance with claim 14 wherein said cylinder means is provided with conduit means for introducing pressurized hydraulic fluid into said cylinder means at the side of said piston means opposite to said rod means so that said piston means is hydraulically locked with respect to said cylinder means at its extended position.
- 16. Load sensing device in accordance with claim 15 wherein said piston means is directly connected with said load sensing rod means, said cylinder means being axially slidably received in casing means which is adapted to be driven by said axial movement means, said transducer means being disposed in said casing means so as to receive a pressure from said hydraulic cylinder means.
- 17. Load sensing device in accordance with claim 16 wherein said casing means is axially slidably but nonrotatably supported by said housing and wherein said axial movement means includes a ring nut member having an internal screw in mating engagement with an external screw provided on said casing means and an electric motor for rotating said ring nut member.
- 18. Load sensing device in accordance with claim 15 further including disc means secured at one side thereof to the other end of said load sensing rod means and carrying at the other side thereof said transducer means, and piston rod means having one end thereof secured to said piston means and the other end thereof adapted to engage with said transducer means.
- 19. Load sensing device in accordance with claim 18 wherein said axial movement means includes an intermediate member rotatably supported by said housing and having at its inner surface an internal screw in mating engagement with an outer screw provided on said cylinder means to allow said cylinder means to move axially, said rotatable member having external gear teeth formed at outer end thereof, and a rotatable shaft having a pinion in meshing engagement with said external gear teeth of said rotatable member.
- 20. Load sensing device in accordance with claim 18 wherein said cylinder means has an end plate for closing an open end of said cylinder means and spring means disposed between said piston means and said end plate so as to apply a biasing force to said piston means towards its retracted position.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of co-pending United States Application Ser. No. 738,061, filed Nov. 2, 1976, entitled "ROLLING MILL", now abandoned.
The present invention relates to rolling mills including a plurality of roll stands arranged in series. More particularly, the present invention relates to means for measuring forces prevailing in materials or workpieces which extend between two adjacent roll stands.
During the rolling operation of a multistand rolling mill, if excessive force acts on a workpiece between a given pair of stands of the rolling mill, the workpiece will tend to bow between the pair of stands and in an extreme case to deflect from the pass line of the rolling mill. On the other hand, if excessive tension acts on the workpiece between the pair of stands, the workpiece will tend to slip at the roll nip. In an extreme case, the workpiece will neck down or decrease in width and in thickness, and will often break. Variations in the inter-stand compressive and tensile force will cause trouble in the rolling mill operation and have detrimental effects on the rolled product gauge or shape.
In order to eliminate such inconvenience in the rolling operation, it has heretofore been known to be necessary to perform continuous measurement of forces in the workpiece between adjacent roll stands so that the rotating speeds of the rolls in such roll stands can be controlled in accordance with the results of the measurement so as to ceaselessly maintain the inter-stand force of the workpiece between the adjacent roll stands at a desired value. For this purpose, conventionally, a looper has been provided between a given pair of roll stands for detecting the amount of deflection of the workpiece from a standard height. The amount of deflection is converted into the value of a force acting in the material or workpiece being rolled. The looper was very effective in measuring the force acting in the material being rolled in the case of a very thin material such as a strip steel. However, when the materials being rolled are of such thick gauges that loops cannot or can hardly be formed between roll stands, the looper could not be used. In the case of such thick materials, therefore, the values of forces acting in the materials being rolled have been obtained through calculation based on the change in roll driving current in a specific roll stand when the leading end of the workpiece is being captured by the next roll stand. A change in roll nip pressure in said specific roll stand may additionally be used in such calculation of the force in the workpiece.
However, such known method is disadvantageous since the results of measurement are often affected by the temperature and gauge of the material being rolled and by such operating conditions as acceleration and deceleration of the roll driving motor. Further, it is difficult to use the method for controlling the force in the workpiece between two adjacent roll stands during rolling operation. Particularly, it is extremely difficult through this method to attain stress-free control of the material between two adjacent roll stands during continuous rolling operation.
In the U.S. Pat. No. 3,290,912 issued on Dec. 13, 1966 to Warren Reid, there is disclosed a rolling mill in which tensile or compressive force in a rolling material between two adjacent roll stands can be continuously measured during rolling operation so that the force in the rolled material can be controlled as described. According to the teachings of the patent, force sensing transducers are mounted in each stand in such a manner that they sense and measure the horizontal forces acting between roll chocks and framemembers in the stand. However, in the arrangement as taught by the patent, difficulties may be encountered in removing and reinstalling the roll assemblies on the frame members because the force sensing transducers are disposed between the frame members and the work roll chocks and they may interfere with the roll assemblies during the operation of such removal and reinstallation. Further, in this patent, there is no means for protecting the load measuring device from failure under an excessive load.
The U.S. Pat. No. 3,214,970 issued on Nov. 2, 1965 to Rune Flinth discloses a rolling mill for wire products wherein tensile forces in wires are continuously measured. According to the teaching of the patent, each roll stand is supported by resilient members and horizontal thrust forces on the roll stand are measured by pressure sensitive measuring means. However, the proposal in this patent will be limited to applications to rolling mills for thin products such as wires and cannot readily be embodied in rolling mills for thick products since roll stands must be resiliently supported.
In the U.S. Pat. No. 3,375,688 issued on Apr. 2, 1968 to Louis H. Taylor there is disclosed an apparatus for rolling metal strips and sheets which includes a work roll too small to be driven through its neck. In the apparatus disclosed in this patent, sensing means are arranged very close to the small diameter work roll so as to directly detect deflection of the work roll. Thus, the deflection of the small diameter work roll can be detected with a relatively high degree of accuracy. However, mounting and demounting of the sensing means is troublesome because the sensing means and its piping or wiring must be located adjacent to the small diameter work roll within the stand housing. In addition, the operation of mounting the sensing means requires careful attention because the sensing means must be mounted to leave a very small gap between the sensing means and the small diameter work roll. Furthermore, if the workpiece being rolled is bowed during rolling operation, the sensing means would be broken by the bowed workpiece, because the sensing means is to close to the pass line.
The U.S. Pat. No. 3,818,742 issued on June 25, 1974 to Jack Maltby et al. discloses a cantilever rod or bar rolling mill having a pair of roll chocks each of which supports one work roll. Each roll chock has loading means disposed in a recess formed in one side surfce thereof and sensing means located in another recess provided in the opposite side surface thereof. In use, the loading means is actuated so that the sensing means is preloaded to detect variation in the horizontal force acting on the work roll. In this rolling mill, however, the roll chock and the sensing means cannot be separatly assembled into or disassembled from the rolling stand housing because the roll check must be assembled into the stand housing after the sensing means is mounted on the roll chock and because the sensing means must be removed from the roll chock after the roll chock is removed from the stand housing. In addition, electrical cables extending to the sensing means must be housed in a very small space inside of the roll stand housing. Thus, maintenance and replacement operations are troublesome and timeconsuming. Furthermore, the sensing means used in this rolling mill has no means for protecting the sensing means from being broken by an excessive load.
It is therefore an object of the present invention to provide rolling mills having improved means for measuring forces in workpieces which are being rolled.
Another object of the present invention is to provide means for continuously measuring forces in workpieces being rolled in rolling mills.
A further object of the present invention is to provide means for measuring forces in workpieces in rolling mills with simple and effective means for preventing excessive load from being imposed on the force measuring means.
A still further object of the present invention is to provide means for measuring force in rolling mills which does not interfere with roll assemblies during operation of removal and reinstallation of the roll assemblies and which is not precluded from being assembled into and disassembled from the roll stand by the roll assemblies.
A still further object of the present invention is to provide rolling mills having a tension and compression force measuring means which is free from the aforementioned drawbacks of the known arrangements.
According to the present invention in order to accomplish the above and other objects, the rolling mill includes a plurality of roll stands, each having a frame and roll chock means for supporting the associated work rolls, and force measuring means provided in at least one of the roll stands. In the roll stand provided with the force measuring means, one of the roll chock means is adapted to be movable within a limited extent parallel to the rolling direction. A load sensing rod is provided so as to extend parallel to the direction of movement of the roll chock means through or outside the frame and is in contact at one end with the roll chock means. The load sensing rod is associated with transducer means which is mounted in such a position that it is subjected to a pressure transmitted thereto from the associated roll chock means through the load sensing rod. Means is further provided for effecting axial movement of the rod so that it is projected or extended into contact with the associated roll chock means and retracted away from the roll chock means and retracted away from the roll chock means. Thus, when it is desired to remove the roll chock means from the frame of the roll stand together with the rolls mounted thereon, the load sensing rod can be retracted into a position that it does not interfere with the roll chock means. Hydraulic means is further provided for providing a support for the load detecting rod under a predetermined hydraulic pressure, so that the rod is shifted under an excessive load to prevent an excessive force from being transmitted to the transducer means.
According to one mode of the present invention, the load sensing rod is, at the other end, secured to or integrally formed with a piston which is reciprocatingly movable in a cylinder. The cylinder is in turn slidably received in a casing which is axially movable and provided with means for effecting such axial movement so that the load sensing device can be bodily moved toward and away from the roll chock. The transducer means may be in the form of a load cell and is disposed in the casing in such a manner that it is subjected to a pressure applied thereto through the cylinder. The piston is spring-biased to the retracted position and means is provided for introducing hydraulic pressure into the cylinder so that the piston is hydraulically locked with respect to the cylinder at the extended position. Thus, in operation, hydraulic pressure is introduced into the cylinder with the casing at the fully retracted position so as to lock the piston with respect to the cylinder. Thereafter, the casing is axially moved to advance the load sensing rod toward the roll chock until it contacts the roll chock with an appropriated pressure.
In a further and more preferable mode of the present invention, the transducer means is mounted between the load sensing rod and a piston rod on a piston which is reciprocatingly movable in a cylinder between an extended position and a retracted position. Means is provided for moving the cylinder in the axial direction and holding it at a desired position. The position is spring-biased toward the retracted position and there is provided means for introducing hydraulic pressure into the cylinder so as to hydraulically lock the piston with respect to the cylinder at the extended position. The arrangement is advantageous over the previously described mode of arrangement of the present invention in that the measurement is not affected by the friction which may be produced due to the sliding movement of the cylinder.
US Referenced Citations (2)
| Number |
Name |
Date |
Kind |
|
3375688 |
Taylor |
Apr 1968 |
|
|
3818742 |
Maltby et al. |
Jun 1974 |
|
Foreign Referenced Citations (2)
| Number |
Date |
Country |
| 968,271 |
Mar 1958 |
DEX |
| 2,220,835 |
Nov 1972 |
DEX |
Continuation in Parts (1)
|
Number |
Date |
Country |
| Parent |
738061 |
Nov 1976 |
|
Patent Grant
4116028
