GB1573708A - Roll stands for rolling mills - Google Patents

Description

(54) ROLL STANDS FOR ROLLING MILLS (71) We, SUMITOMO METAL INDUSTRIES, LTD., a Japanese corporation, of No. 15, 5-chome, Kitahama, Higashi-ku, Osaka, Japan do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates generally to roll stands for rolling mills which include a plurality of roll stands arranged in series.

More particularly, the present invention relates to means for measuring forces prevailing in workpieces which, in operation of the rolling mill, extend between two adjacent roll stands.

During the operation of a multistand rolling mill, if an excessive compressive 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 an excessive tension acts on the workpiece between the pair of stands, the workpiece will tend to slip at the roll nip. If 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 acting on a workpiece will cause trouble in the rolling mill operation and have detrimental effects on the gauge or shape of the rolled workpiece.

With a view to eliminating such errors in the rolling operation, it is known to make continuous measurements of forces in the workpiece between adjacent roll stands so that the rotational speeds of the rolls in the roll stands can be controlled in accordance with the results of the force measurements so as to maintain the force acting on the workpiece between the adjacent roll stands at a desired value. For this purpose, 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 workpiece being rolled. The looper is very effective in measuring the force acting in the workpiece being rolled in the case of very thin workpieces such as strip steel.However, when the workpieces being rolled are of such thick gauge that they cannot deflect laterally between roll stands or can only do so with difficulty, the looper is not much use. When rolling thick workpieces, therefore, the values of forces acting in the workpiece between roll stands have been obtained by calculation based on the change in rolldriving current in a particular roll stand when the leading end of the workpiece is being captured by the next roll stand. A change in roll nip pressure in the particular roll stand may additionally be used in such calculations of the force in the workpiece.

However, this known method is disadvantageous since the results of measurements are often affected by the temperature and gauge of the workpiece being rolled and by such operating conditions as acceleration and decleration 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 operations. Particularly it is extremely difficult, by this method, to attain stress-free control of the workpiece between two adjacent roll stands during rolling operations.

In the United States Patent No. 3,290,912 a rolling mill is disclosed in which tensile or compressive forces in a workpiece being rolled between two adjacent roll stands can be continuously measured during rolling operations so that the force in the workpiece can be controlled as desired. For this purpose, force sensing transducers are mounted in each rollstand of the mill in such a manner that they sense and measure the horizontal forces in the direction of rolling acting between the roll chocks (which support the rolls) and frame members of the stand.However, in the arrangement disclosed by this Patent, difficulties may be encountered in removing and reinstalling the roll assemblies in 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, no means is disclosed for protecting the load measuring device from failure under an excessive load.

United States Patent No. 3,214,970 discloses a rolling mill for wire products wherein tensile forces in wires are continuously measured. 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 is limited in application to rolling mills for thin products such as wires, and cannot readily be embodied in rolling mills for thick workpieces because the roll stands are resiliently supported.

United States Patent No, 3,375,688 discloses an apparatus for rolling metal strips and sheets which includes a work roll too small to be driven through its neck. In this apparatus sensing means are arranged very close to the small diameter work roll so as to detect deflection of the work roll directly, and 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 is located adjacent 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 of its proximity to the pass line.

United States Patent No. 3,818,742 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 surface 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 separately assembled in or disassembled from the rolling stand housing because the roll chock must be assembled in the stand housing after the sensing means is mounted on the rollchock 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 leading to the sensing means must be housed in a very small space inside the roll stand housing. Thus, maintenance and replacement operations are troublesome and time-consuming.

Furthermore, the sensing means used in this rolling mill has no means for protection against being broken by an excessive load.

It is therefore an object of the present invention to provide a roll stand for a rolling mill having improved means for measuring forces in workpieces which are being rolled, the means being effective for preventing excessive loads from being imposed on the force measuring means. It is a further object that the means for measuring forces in the workpieces should not interfere with the roll assemblies during removal and reinstallation of the roll assemblies, and is not precluded from being assembled in and disassembled from the roll stand by the roll assemblies.

To this end, according to the invention, a roll stand for a rolling mill, which includes a plurality of roll stands arranged in series, comprises a frame, at least a pair of work rolls, separate roll chock means supporting the work rolls, at least one of the roll chock means being mounted on the frame in such a way that the chock means, together with the work roll supported by it, is movable in a roll gap-adjusting direction perpendicular to the axis of the work roll, means for adjusting the position of the movably mounted chock means to set the roll gap between the work rolls to a desired magnitude, and force measuring means for measuring the force in a workpiece in its direction of travel when the roll stand is in operation rolling a workpiece which is travelling between the roll stand and an adjacent roll stand in the series, the force measuring means comprising means mounting the chock means of at least one of the work rolls on the frame to enable it to move to a limited extent in a direction parallel to the direction of travel of the workpiece, load sensing rod means which extends in a direction substantially parallel to the said direction of travel and which is arranged to contact at one end the chock means which is movable in the direction parallel to the said direction of travel, transducer means which is positioned outside of the frame and which is in contact with the other end of the load sensing rod means so as to receive a force transmitted axially through the rod means and produce an electric signal which gives an indication of the magnitude of the force, means for effecting axial movement of the rod means together with the transducer means to move the one end of the rod means into and out of contact with the roll chock means, and hydraulic means for supporting the transducer means with a force uP to a predetermined maximum, the hydraulic means allowing the transducer means and the rod means to move upon the application to the rod means by the chock means of a force above the predetermined maximum in such a way that a force above the predetermined maximum is not applied to the transducer means.

In accordance with a further aspect of the invention, a load sensing device for measuring a force in a workpiece in its direction of travel between two adjacent roll stands in which the workpiece is rolled and each of which includes a frame, at least a pair of work rolls, and separate roll chock means supporting the work rolls, comprises a housing adapted to be mounted on the outside of the frame of one of the roll stands so that load sensing rod means of the device is arranged to contact at one end one of the roll chock means of the roll stand, transducer means in contact with the other end of the load sensing rod means so as to receive a force transmitted axially through the rod means and generate an electrical signal which gives an indication of the magnitude of the force, means for effecting axial movement of the rod means so that its one end can be moved into and out of contact with said one roll chock means, and hydraulic means including hydraulic cylinder means and piston means disposed in the cylinder means, the piston means being arranged to support the transducer means with a force up to a predetermined maximum so that, when a force acting through the rod means and the transducer means towards the piston means exceeds the predetermined maximum, the piston and the transducer means move so that a force above the predetermined maximum is prevented from being applied to the transducer means.

In a preferred embodiment of the present invention, means is provided for moving the cylinder in an axial direction and holding it at a desired position. The piston is springbiased towards the retracted position and means is provided for introducing hydraulic fluid under pressure into the cylinder to hydraulically lock the piston with respect to the cylinder at the extended position.

Various examples of roll stands constructed in accordance with the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a partially cut-away side elevational view of an example of a horizontal roll stand embodying the present invention; Figure 2 is a section plan view taken along the line II-II in Figure 1; Figure 3 is a sectional view showing a mechanism for suspending an upper roll chock in the stand of Figures 1 and 2; Figure 4 is a sectional view showing details of a load measuring device which is incorporated in the roll stand of Figures 1 to 3; Figure 5 is a view similar to Figure 1 but showing an example of a horizontal roll stand in which the load measuring device is mounted differently; Figure 6 is a sectional plan view taken along the line VI-VI in Figure 5;; Figure 7 is a partial side elevational view of a horizontal roll stand showing another manner of mounting the load measuring device on the roll stand; Figure 8 is a plan view of an example of a vertical roll stand embodying the features of the present invention; Figure 9 is a front view of the roll stand shown in Figure 8; and, Figure 10 is a vertical section view taken along the line X-X in Figure 9.

Figures 1 to 4 show a roll stand of the horizontal type which includes a frame 1 and upper and lower roll chocks 2 and 3 for supporting upper and a lower work rolls 4 and 5, respectively, at the opposite ends thereof. In this embodiment, the lower roll chocks 3 are mounted on the frame 1 in a manner conventional in the art.

Each upper roll chock 2 is resiliently suspended by a mechanism including a pair of bell-crank members 6 mounted on the frame 1 rotatably about horizontal shafts 7. Each bell-crank member 6 has, at one of its ends, a hook member 8 which engages a cooperating flange 2a formed on the upper roll chock 2 at its upper end. The other end of each bell-crank member 6 is connected through a rod 9 with a spring assembly 10 so that the upper roll chock 2 is resiliently forced upwardly under the action of the spring assembly 10. Figure 1 shows one such mechanism provided at one axial end of the upper roll 4. However, it should be noted that a similar mechanism is also provided at the other axial end.

The upper roll chock 2 is mounted in the frame 1 for movement within a limited extent parallel to the direction of the path of the workpiece. For this purpose, the roll chock 2 is located in the frame 1 with clearances at the forward and rearward sides considered in relation to the movement of the workpiece between the rolls. Furthermore, as shown in Figure 2, the upper roll chock 2 is formed with a pair of L-shaped arms 2b having radially outwardly directed ends 2which are positioned between bracket members 11 mounted on the frame 1 and clamping members 12 with interposition of metal pads or spacers 13. Recommendable material for such pads 13 is a laminated composite comprising a plurality of alternate metal and plastic laminae, as disclosed in United States Patent No. 4,037,450.Tie rods 14 and a turnbuckle 15 are provided for maintaining the clamping members 12 in operative positions. In this mechanism, the metal pads 13 serve to constrain the associated roll chock 2 against movement in the direction of axis of the roll but allow it to move in the direction parallel to the movement of the workpiece as shown by an arrow in Figure 2.

Back-up pressure is applied to each of the upper roll chocks 2 through a mechanism shown in Figure 3. The mechanism includes a thrust receiving member 16 placed on the top portion of the upper roll chock 2 and carrying a self-centering bearing 17 on its outer cylindrical surface. The frame 1 has a hollow cylindrical bracket member 18 which slidably supports the outer race of the bearing 17. An internally threaded member 19 is mounted on the frame 1 and a vertical thrust screw 20 engages the member 19 for adjusting the vertical position of the roll chock 2, thereby setting the gap between the rolls at a desired value. As is well known in the art, the thrust screw 20 withstands the force tending to separate the rolls 4 and 5, and applies downward rolling force to the workpiece through the roll chock 2 and the roll 4 when the workpiece is being rolled by the stand.

The screw 20 is formed with an axial extension 20a having a part-spherical end 20b.

The thrust receiving member 16 on the upper roll chock 2 is formed with a cylindrical bore 16a having a part-spherical bottom 16b. The extension 20a of the screw 20 is inserted into the bore 16a. The radius of the curvature of the bottom 1 6b of the bore 16 is greater than that of the end 20b on the screw extension 20a so that the extension 20a makes point contact with the bottom 1 6b of the bore 1 6a at or in the vicinity of the centre of the selfcentering bearing 17. Thus, it will be understood that the mechanism is effective to set and support the roll chock 2 at a desired vertical position while allowing it to swing about the center of the bearing 17 in accordance with the reaction force applied thereto from the workpiece through the corresponding working roll.

Referring back to Figure 1, it will be seen that there are provided a pair of load sensing devices 21 at the forward and rearward sides of the upper roll chock 2. Since the devices 21 have the same structures and the same functions, only one of them will hereinafter be described with reference to Figure 4.

Referring now to Figure 4, the numeral 40 indicates the load sensing device shown generally at 21 in Figures 1 and 2 and including a load sensing rod 41 having an end piece 42 adapted to be brought into contact with the upper roll chock 2. A sleeve member 43 having an end flange 44 is inserted into a hole 45 in the frame 1 and axially slidably receives the rod 41 through bearing 46.

The load sensing rod 41 has a disc 47 secured thereto at the end opposite to the end piece 42. The disc 47 carries a load transducer 48. On the frame 1, there is mounted a guide plate 49 which has a circular guide hole 50 and the transducer carrying disc 47 is slidably received in and guided by the hole 50 on the plate 49.

The plate 49 carries a cylindrical housing 51 in which rotatable member 52 is mounted through bearings 53 and 54. An annular retaining plate 55 is secured to an outer end of the housing 51 for maintaining the rotatable member 52 and the bearing 53 and 54 against axial movement. The rotatable member 52 is formed at an outer end with external gear teeth 52a which are in meshing engagement with a pinion 56. The pinion 56 is secured to a shaft 57 and driven by a suitable power source such as an electric motor (not shown).

Within the rotatable member 52, there is axially movably but non-rotatably disposed a hydraulic cylinder 58 having an end plate 59 which closes an open end of the cylinder 58.

A piston 60 is slidably disposed in the cylinder 58 and has a piston rod 61 extending through the end plate 59. A hydraulic conduit 62 is provided for supplying pressurized hydraulic fluid into the cylinder 58 at the side of the piston 60 opposite to the piston rod 61.

Between the piston 60 and the end plate 59, there is disposed a spring 63 which biases the piston to the retracted position, that is, toward left in Figure 4.

The rotatable member 52 is formed on its inner surface with a internal screw which is in engagement with a corresponding external screw provided on the hydraulic cylinder 58, so that the cylinder 58 is moved in the axial direction as the rotatable member 52 is rotated through the pinion 56.

The piston rod 61 has an end flange 61a at its outer end which is adapted to engage with the load transducer 48. The end flange 61a on the piston rod 61 is maintained in contact with the transducer 48 through a plurality of L-shaped tie members 64 which are attached to the disc member 47 by nuts 65.

In this arrangement, when the hydraulic pressure is released from the cylinder 58, the piston 60 is formed into the retracted position under the influence of the spring 63.

Thus, the load sensing rod 41 is also retracted through the tie members 64 and the disc 47.

The rod 41 can further be retracted by bodily displacing the hydraulic cylinder 58 toward left through rotation of the member 52.

In operation, hydraulic pressure is introduced into the cylinder 58 so as to shift the piston 60 to the extended position against the action of the spring 63. As in the previous embodiment, the piston 60 is hydraulically locked in this position with respect to the cylinder 58. Then, the pinion 56 is driven by the motor to shift the cylinder 58 axially rightwardly through the rotatable member 52 until the end piece 42 on the rod 41 is brought into contact with the roll chock 2.

The load sensing device 40 as mentioned above may be mounted on the roll stand frame 1 as shown in Figure 5 and 6. In this case, the sleeve member 43 of the load sensing device 40 is located to extend along and outside of the outer surface 70 of the frame 1 parallel to and remote from the pass line so that the end piece 42 of the sensing rod 41 can be brought into contact with an outer extending portion 71 of the upper roll chock 2 below the L-shaped arm 2b, as shown in Figure 5. The sleeve member 43 may be secured to the frame by a suitable fastening means (not shown). The end flange 44 of the sleeve member 43 and the guide plate 49 are mounted on an auxiliary plate 72, which is in turn fixed to the outside of the frame opposite to the upper roll chock 2, as shown in Figure 6.With this arrangement, there is no need for provision of a hole in the frame for insertion of the sleeve member 43, and therefore, the load sensing device is easily applicable to the conventional rolling stands without substantial modification of the stands.

Alternatively, the load sensing device 40 can be mounted on the outer surface 70 of the frame 1 by means of suitable fixture means such as bands 73, as shown in Figure 7. In this case, the sleeve member 43 and the sensing rod 41 are shorter than in the arrangement shown in Figures 5 and 6. In addition, it is not necessary to support the sleeve member 43. It should be noted that the load sensing device 21 as shown in Figure 3 can be mounted on the frame 1 in a similar manner to that for the device 40 described with reference to Figures 5 to 7.

Now, referring to Figures 8 to 10, there is shown a roll stand of the vertical type which incorporates therein the same load sensing device as that shown in Figure 4. This roll stand includes upper and lower frames 81 and 82, and roll chocks 83 and 84 for supporting drive side and work side work rolls 85 and 86, respectively, at their opposite ends. In this embodiment, the drive side roll chocks 83 are mounted on the frames 81 and 82 in the conventional manner. On the other hand, the work side roll chocks are mounted on the frames 81 and 82 to be movable within a limited extent in the direction parallel to the pass line, in a manner similar to that of the upper roll chock 2 shown in Figures 1 to 3.

To be brief, the work side roll chock 84 has a pair of hooks 87 for assembly and disassembly from the roll stand by suitable hoisting means (not shown). The roll chock 84 also has a pair of side flanges 88 formed at the side thereof opposite to the exposed portion of the work roll and adapted to engage, respectively, a pair of roll balance beams 89 formed on the frame. Further, the roll chock 84 includes a pair of outwardly extending portions 84a which are adapted to ride on the outer surface of the frame 81. The hook 87 has an outwardly extending portion 90 formed at an intermediate portion thereof and adapted to be interposed between a bracket member 91 and a clamping member 92 with interposition of pads or spacers 93.

Tie rods 94 and a turnbuckle 95 are provided for maintaining the clamping members 92 in operative positions. The pads 93 serve to constrain the associated roll chock 84 against movement in the direction of axis of the roll but allows it to move in the direction parallel to the movement of the workpiece.

The work side roll chock 84 is adapted to be applied with back-up pressure from a mechanism 96 which has a similar construction to that of the back-up mechanism as shown in Figure 3. The drive side roll chock 83 also has similar back-up mechanism.

The upper frame 81 has a pair of the same load sensing devices as the load sensing device 40 as shown in Figure 4, one of which is mounted on the delivery side of the upper frame 81 and the other of which is mounted on the entry side of the upper frame. These load sensing devices 40 are mounted to the upper frame 81 in the same manner. Namely, each load sensing device 40 is mounted on the outer face of the upper frame 81 opposite to the roll chock 84 in such a manner that its sleeve member 43 and hence its sensing rod 41 extend through a hole formed in the upper frame 81 in the direction parallel to the direction of the pass line so that the end piece 42 of the load sensing device 40 can be brought into contact with the roll chock 84, in similar manner to that shown in Figure 4.The manner of mounting the load sensing device 40 on the upper frame 81 is quite similar in all details to the manner of mounting the device 40 on the horizontal type roll stand as shown in and described with reference to Figure 4.

Operation is also totally similar to that described with reference to Figure 4. Therefore, detailed explanation will be omitted here. It should be noted that the load sensing devices 40 may be mounted on the lower frame 82 and that they may be mounted in similar manner to that shown in Figures 5 to 7.

The invention has thus been shown and described with reference to specific embodiments, however, it should be noted that the invention is in no way limited to the details of the illustrated structures but changes and modifications may be made within the scope of the appended claims. For example, when it is desired to measure either one of compression and tensile forces in the workpiece, only one load measuring device may be provided on the appropriate side of the movable roll chock. Further, such measuring device or devices may be provided in association with the lower roll chock or drive side roll chock.

WHAT WE CLAIM IS:- 1. A roll stand for a rolling mill which includes a plurality of roll stands arranged in series, the roll stand comprising a frame, at least a pair of work rolls, separate roll chock means supporting the work rolls, at least one of the roll chock means being mounted on the frame in such a way that the chock means, together with the work roll supported by it, is movable in a roll gap-adjusting direction perpendicular to the axis of the work roll, means for adjusting the position of the movably mounted chock means to set the roll gap between the work rolls to a desired magnitude, and force measuring means for measuring the force in a workpiece in its direction of travel when the roll stand is in operation rolling a workpiece which is travelling between the roll stand and an adjacent roll stand in the series, the force measuring means comprising means mounting the chock means of at least one of the work rolls on the frame to enable it to move to a limited extent in a direction parallel to the direction of travel of the workpiece, load sensing rod means which extends in a direction substantially parallel to the said direction of travel and which is arranged to contact at one end the chock means which is movable in the direction parallel to the said direction of travel, transducer means which is positioned outside of the frame and which is in contact with the other end of the load sensing rod means so as to receive a force transmitted axially through the rod means and produce an electric signal which gives an indication of the magnitude of the force, means for effecting axial movement of the rod means together with the transducer means to move the one end of the rod means into and out of contact with the roll chock means, and hydraulic means for supporting the transducer means in contact with the rod means with a force up to a predetermined maximum, the hydraulic means allowing the transducer means and the rod means to move upon the application to the rod means by the chock means of a force above the predetermined maximum in such a way that a force above the predetermined maximum is not applied to the transducer means.

2. A roll stand according to claim 1, in which the load sensing rod means extends through a hole in the frame of the roll stand into contact at said one end with the chock means which is movable in the direction parallel to the said direction of travel.

3. A roll stand according to claim 1, in which the load sensing rod means is located outside the frame of the roll stand, that is on the side of the frame remote from that on which the workpiece passes during operation.

4. A roll stand according to any one of claims 1 to 3, in which the hydraulic means includes hydraulic cylinder means and piston means disposed in the cylinder means, the piston means being connected to the load sensing rod means with the transducer means interposed therebetween, and the axial movement means being in engagement with the hydraulic cylinder means.

5. A roll stand according to claim 4, in which the axial movement means includes a rotatable member disposed around the hydraulic cylinder means and screwed thereon, and means for rotating the rotatable member.

6. A roll stand according to any one of the preceding claims, in which the roll stand is of the horizontal type, the work rolls and chock means comprising upper and lower work rolls and upper and lower chock means supporting the upper and lower rolls respectively, the upper chock means being mounted to move upwards and downwards together with the upper roll, and the roll gap setting means abuts against the upper chock means to withstand the force which, in operation, tends to move the upper roll and the upper chock means upwards.

7. A roll stand according to claim 6, in which the upper chock means is mounted for swinging movement about a point above the axis of rotation of the upper roll to provide the movement parallel to the direction of travel of the workpiece, and the roll gap setting means includes a thrust member which makes point contact with the upper chock means substantially at said point above the axis of rotation of the upper roll.

8. A roll stand according to claim 7, in which the upper roll chock means is mounted by self-centring bearing means which allows the swinging movement.

9. A roll stand according to claim 7 or claim 8, in which the thrust member has a part-spherical lower end which engages with a part-spherical seat on the upper roll chock means, the part-spherical seat having a radius of curvature greater than that of the lower end of the thrust member.

10. A roll stand according to any one of the preceding claims, in which the roll chock means which is movable parallel to said direction of travel is located in the frame with clearances at the forward and rearward sides thereof in said direction of travel and is provided with means for constraining it against movement in the direction of the axis of the work roll supported thereby.

11. A roll stand according to claim 10, in which the means for constraining axial movement of the chock means is a laminated composite comprising a plurality of alternate metal and plastic laminae.

12. A roll stand according to claim 1, in which the roll stand is of the vertical type which comprises upper and lower frames,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (19)

**WARNING** start of CLMS field may overlap end of DESC **. the lower roll chock or drive side roll chock. WHAT WE CLAIM IS:-

1. A roll stand for a rolling mill which includes a plurality of roll stands arranged in series, the roll stand comprising a frame, at least a pair of work rolls, separate roll chock means supporting the work rolls, at least one of the roll chock means being mounted on the frame in such a way that the chock means, together with the work roll supported by it, is movable in a roll gap-adjusting direction perpendicular to the axis of the work roll, means for adjusting the position of the movably mounted chock means to set the roll gap between the work rolls to a desired magnitude, and force measuring means for measuring the force in a workpiece in its direction of travel when the roll stand is in operation rolling a workpiece which is travelling between the roll stand and an adjacent roll stand in the series, the force measuring means comprising means mounting the chock means of at least one of the work rolls on the frame to enable it to move to a limited extent in a direction parallel to the direction of travel of the workpiece, load sensing rod means which extends in a direction substantially parallel to the said direction of travel and which is arranged to contact at one end the chock means which is movable in the direction parallel to the said direction of travel, transducer means which is positioned outside of the frame and which is in contact with the other end of the load sensing rod means so as to receive a force transmitted axially through the rod means and produce an electric signal which gives an indication of the magnitude of the force, means for effecting axial movement of the rod means together with the transducer means to move the one end of the rod means into and out of contact with the roll chock means, and hydraulic means for supporting the transducer means in contact with the rod means with a force up to a predetermined maximum, the hydraulic means allowing the transducer means and the rod means to move upon the application to the rod means by the chock means of a force above the predetermined maximum in such a way that a force above the predetermined maximum is not applied to the transducer means.

2. A roll stand according to claim 1, in which the load sensing rod means extends through a hole in the frame of the roll stand into contact at said one end with the chock means which is movable in the direction parallel to the said direction of travel.

3. A roll stand according to claim 1, in which the load sensing rod means is located outside the frame of the roll stand, that is on the side of the frame remote from that on which the workpiece passes during operation.

4. A roll stand according to any one of claims 1 to 3, in which the hydraulic means includes hydraulic cylinder means and piston means disposed in the cylinder means, the piston means being connected to the load sensing rod means with the transducer means interposed therebetween, and the axial movement means being in engagement with the hydraulic cylinder means.

5. A roll stand according to claim 4, in which the axial movement means includes a rotatable member disposed around the hydraulic cylinder means and screwed thereon, and means for rotating the rotatable member.

6. A roll stand according to any one of the preceding claims, in which the roll stand is of the horizontal type, the work rolls and chock means comprising upper and lower work rolls and upper and lower chock means supporting the upper and lower rolls respectively, the upper chock means being mounted to move upwards and downwards together with the upper roll, and the roll gap setting means abuts against the upper chock means to withstand the force which, in operation, tends to move the upper roll and the upper chock means upwards.

7. A roll stand according to claim 6, in which the upper chock means is mounted for swinging movement about a point above the axis of rotation of the upper roll to provide the movement parallel to the direction of travel of the workpiece, and the roll gap setting means includes a thrust member which makes point contact with the upper chock means substantially at said point above the axis of rotation of the upper roll.

8. A roll stand according to claim 7, in which the upper roll chock means is mounted by self-centring bearing means which allows the swinging movement.

9. A roll stand according to claim 7 or claim 8, in which the thrust member has a part-spherical lower end which engages with a part-spherical seat on the upper roll chock means, the part-spherical seat having a radius of curvature greater than that of the lower end of the thrust member.

10. A roll stand according to any one of the preceding claims, in which the roll chock means which is movable parallel to said direction of travel is located in the frame with clearances at the forward and rearward sides thereof in said direction of travel and is provided with means for constraining it against movement in the direction of the axis of the work roll supported thereby.

11. A roll stand according to claim 10, in which the means for constraining axial movement of the chock means is a laminated composite comprising a plurality of alternate metal and plastic laminae.

12. A roll stand according to claim 1, in which the roll stand 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 the drive side and work side work rolls respectively, the work side roll chock means being mounted on the frames so that it can move to a limited extent in the direction parallel to the direction of travel of a workpiece through the stand, and the force measuring means being mounted on one of the frames in such a manner that the load sensing rod means thereof can be brought at one end into contact with the work side roll chock means.

13. A load sensing device for measuring a force in a workpiece in its direction of travel between two adjacent roll stands in which the workpiece is rolled and each of which includes a frame, at least a pair of work rolls, and separate roll chock means supporting the work rolls, the device comprising a housing adapted to be mounted on the outside of the frame of one of the roll stands so that load sensing rod means of the device is arranged to contact at one end one of the roll chock means of the roll stand, transducer means in contact with the other end of the load sensing rod means so as to receive a force transmitted axially through the rod means and generate an electrical signal which gives an indication of the magnitude of the force, means for effecting axial movement of the rod means so that its one end can be moved into and out of contact with said one roll chock means, and hydraulic means including hydraulic cylinder means and piston means disposed in the cylinder means, the piston means being arranged to support the transducer means in contact with the rod means with a force up to a predetermined maximum so that, when a force acting through the rod means and the transducer means towards the piston means exceeds the predetermined maximum, the piston and the transducer means move so that a force above the predetermined maximum is prevented from being applied to the transducer means.

14. A load sensing device according to claim 13, in which the hydraulic cylinder means is provided with conduit means for introducing hydraulic fluid under pressure into the cylinder means on the side of the piston means remote from the transducer means so that, in operation, the piston means can be hydraulically locked with respect to the cylinder means at a predetermined hydraulic pressure to determine the predetermined maximum force at which the transducer means is supported.

15. A load sensing device according to claim 14, in which the end of the load sensing rod means remote from its said one end is secured to one side of disc means which carries on its other side the transducer means, and piston rod means having one end thereof secured to the piston means is adapted to engage the transducer means at its other end.

16. A load sensing device according to claim 15, in which the axial movement means comprises an intermediate member rotatably supported by the housing and having an inner surface bearing an internal screw thread in mating engagement with an external screw thread provided on the cylinder means to allow the cylinder means to move axially, the intermediate member having external gear teeth formed at an end thereof, and a rotatable shaft having a pinion in meshing engagement with the external gear teeth of the intermediate member.

17. A load sensing device according to claim 15, in which the cylinder means has an end plate for closing an open end of the cylinder means, and spring means is disposed between the piston means and the end plate so as to apply a biasing force to the piston means towards its retracted position.

18. A roll stand according to claim 1, substantially as described with reference to Figures 1 to 4, Figures 5 and 6, Figure 7, or Figures 8 to 10, of the accompanying drawings.

19. A rolling mill including a plurality of roll stands arranged in series, at least one of the roll stands being in accordance with any one of claims 1 to 12 or claim 18.