Improvements in or relating to rolling mill stands

Abstract

 A rolling mill stand comprises a frame (10), two carriers (14) mounted on the frame (10), for relative lateral movement towards and away from one another, each carrier (14) having removably mounted thereon a roll chock assembly (39) comprising a bearing housing (40) having two spaced apart bearing means (44) and a roll member (45) disposed between and rotatably mounted by said bearing means (44) to provide a roll pass between the roll members, a drive means (25) to rotate each roll member (45), and a detachable coupling (36,37) between the drive means (25) and the roll member (45).

Description

[0001] This invention relates to improvements In or relating to a rolling mill stand for rolling metal.

[0002] Rolling mill stands having working rollers mounted in cantilever manner on roll shafts extending vertically from a gearbox are well known. The main advantages of such cantilever rolling mill stands are easy access to the working rolls, for example for replacing worn rolls, and more compact design compared with conventional non-cantilever roll stands. Due to these advantages, cantilever stands are widely used in rod finishing blocks, in intermediate trains for rod and bar mills, and as vertical stands in rod, bar and light section mills.

[0003] However, a major disadvantage of cantilever rolling mill stands is the very limited rolling load capacity compared with conventional stands. This limited rolling load capacity is due to the unilateral bearing arrangement by which only one bearing is available to carry the full rolling load, compared with two bearings in conventional stands. Due to this limited rolling load capacity, compact cantilever rolling mill stands are very seldom used in rolling mills where such high capacity is required, e.g. a roughing mill, in spite of the fact that a very compact design would be a very great advantage.

[0004] Conventional vertical rolling mill stands for roughing mills have the disadvantage that it is difficult and inconvenient to change rolls when worn, for example because crane access is restricted to a great extent, one conventional rolling mill stand arrangement having this disadvantage is disclosed in U.S. Patent 3,670,587.

[0005] Accordingly, an object of the present invention is to provide a rolling mill stand which avoids the above described disadvantage.

[0006] According to the present invention, we provide a rolling mill stand comprising a frame, two carriers mounted on the frame, for relative lateral movement towards and away from one another, each carrier having removably mounted thereon a roll chock assembly comprising a bearing housing having two spaced apart bearing means and a roll member disposed between and rotatably mounted by said bearing means to provide a roll pass between the roll members, a drive means to rotate each roll member, a detachable coupling between the drive means and the roll member.

[0007] Thus, a rolling mill stand embodying the present invention may be made compact and may have a high rolling load capacity since each roll member is supported by two bearings, one on each side of the roll member, giving a load capacity similar to that of a similar non-cantilevered roll stand. In addition, the chock assemblies can be exchanged as easily as the roll members of known cantilever rolling mill stands due to the removable mounting of the roll chock assemblies on their respective carriers, and due to the detachable coupling between the drive means and the roll member. The relative lateral movement of the carriers permits of roll pass gap adjustment.

[0008] The drive means may comprise a gearbox for each roll member, an output element of the gearbox being detachably connected to the roll member and an input element of the gearbox being driven from a prime mover.

[0009] The output element of the gearbox may extend coaxially with axis of rotation of the roll, member and be connected in end-to-end relationship therewith.

[0010] For example, the output element may comprise a socket in which is detachably received, a roll drive shaft of the roll member, so that the roll drive shaft may be axially withdrawn from the socket during roll chock assembly replacement.

[0011] The socket and roll drive shaft may be provided with interengaging splines to provide the detachable drive connection therebetween, although any other type of key between the roll drive shaft and the socket could alternatively be provided.

[0012] Preferably, the gearbox associated with the or each movable roll chock assembly may be mounted to move laterally with the roll chock assembly, the input element of the gearbox being driven from the prime mover through a drive train permitting of said movement. Alternatively the gearbox may be fixed relative to the frame, the detachable connection between the roll member and gearbox permitting of said lateral movement.

[0013] The axes of rotation of the roll members are preferably vertical, but may be horizontal or inclined to the vertical or horizontal as required.

[0014] Each roll member may comprise a roll having, at opposite ends, integral neck portions carried by said bearing means, or each roll member may comprise a roll ring removably mounted on a shaft, end parts of the shaft being carried by said bearing means.

[0015] Means may be provided to permit of at least one of said roll chock assemblies to be moved relative to the frame to permit of adjustment of the gap between the roll members in the roll pass.

[0016] Each of the carriers may have generally horizontal and vertical support surfaces for the associated roll chock assembly, and the associated roll chock assembly may have corresponding surfaces which, in use, engage the support surfaces of the carrier, the roll chock assembly being detachably mounted on the carrier by releasable fasteners, such as bolts.

[0017] Although the present invention has been developed particularly for use as a roughing mill, a rolling mill stand embodying the present invention may be used for any other desired application, such as rod finishing blocks, intermediate trains for rod and bar mills and as vertical stands in rod, bar and light section mills.

[0018] The invention will now be described in more detail by way of example, with reference to the accompanying drawing, wherein:-

FIGURE I is a side elevation partly in section through a rolling mill stand embodying the invention;

FIGURE 2 is a section on the line 2-2 of Figure I;

FIGURE 3 is a vertical section to an enlarged scale through a roll chock assembly of the stand shown in Figure I;

FIGURE 4 is a vertical section to an enlarged scale showing the mounting of a roll chock assembly on a carrier in the stand of Figure I.

[0019] Referring to the drawings, a fixed frame 10 of the rolling mill stand comprises a pair of spaced parallel transversely extending members II, reinforced by webs 12, which extend transversely of the pass line P of the stand, and longitudinally extending members 13, which extend parallel to and are disposed on opposite sides of the pass line P.

[0020] The longitudinal members 13 are supported on foundations F and the transverse members 11 are, as shown in the Figures, clear of walls W1 and W2 of a pit formed in the foundations F. If desired, additional support for the transverse members 11 may be provided by extending the walls W2 as shown in chain dotted line in Figure 2.

[0021] Slidably mounted on the transverse members I are two carriers 14. Oppositely directed flanges 15 of the carriers 14 engage the transversely extending members II and permit of movement of the carriers 14 transversely of the pass line P under the control of wedge assemblies 16.

[0022] Each wedge assembly 16 for each carrier comprises two spaced wedges 17, each of which is raised and lowered by a lead screw 18 rotatable by a hand wheel 19 via a common drive shaft. Each wedge 17 is in engagement with an associated one of a pair of inclined surfaces 20 of the associated carrier 14. In addition, each carrier 14 has connected thereto by a trunnion 21 between the wedges, a piston rod 22 of a hydraulic cylinder 23 which is connected by a trunnion 24 to the frame 10. Thus by operation of the cylinder 23 to retract the piston rod 22, after completion of manual wedge adjustment to the desired roll gap, the wedges 17 are forced into engagement with the inclined surfaces 20 to eliminate any play in the wedge assembly.

[0023] Each carrier 14 is rigidly connected to its own gearbox 25 having an input element in the form of a shaft 26 connected by a telescopic shaft 27 to a prime mover 28 comprising an electric motor. Each gearbox 25 comprises a pair of pinions 29a, 29b having in the present example a reduction ratio of 1.25 : I. The pinion 29a on the input side of the gearbox is connected by a splined connection 30 to a bevel gear/epicyclic gear assembly providing a high reduction ratio of, in the present example 72 : I. Thus each gearbox 25 provides a high reduction ratio, in the present example 90 : I overall.

[0024] Each carrier 14 has an upwardly facing generally horizontal support surface 31 (see Figure 4) and a generally vertical support surface 32 provided on a vertical flange 33 of the carrier. Each carrier 14 has an opening 34 provided in a base part 14_G thereof to provide access to an output element of the associated gearbox 25 in the form of a splined socket 36 in the output pinion 29b to drivably but detachably receive a correspondingly splined end part 37 of a roll drive shaft 38 which depends downwardly from a roll chock assembly 39 removably mounted on each carrier 14 in engagement with the support surfaces 31 and 32.

[0025] Thus, the'engagement between the splines 36, 37 provides a detachable coupling, and sufficient relative axial movement between the shaft 38 and socket 36 would allow the splines to disengage.

[0026] As best shown in Figure 3, each roll chock assembly 39 comprises a generally trunnion shaped housing 40 having two spaced parallel limbs 41 which extend, in use, horizontally and are connected to a vertically extending part 42 by bolts 43. The limbs 41 carry conventional roller bearings 44 which rotatably mount a roll member 45 as a result of engagement of the inner race of the bearings 44 on neck parts 46 formed integrally with the roll member 45. The roll member 45 further comprises a roll drive shaft which extends downwardly and engages with the gearbox as hereinbefore described.

[0027] Alternatively, if desired, the roll member may comprise a roll ring fixed in conventional manner onto a shaft, the bearings 44 engaging parts of the shaft.

[0028] The roll drive shaft 38 is received within a central bore 47 of the remainder of the roll member 45 and torque is transmitted via a key 48 at the top of the shaft 38. As a result, the drive shaft 38 does not experience any roll load and so is not deflected.

[0029] Referring now particularly to Figure 4, each roll chock assembly 39 is mounted on its associated carrier 14 by positioning the roll assembly 39 above the carrier 14 in the position shown in Figure 4, and then lowering the roll assembly until the undersurface 49 of the lower limb 41 engages the upwardly facing support surface 31, whilst the outwardly facing surface 50 of the vertically extending part 42 engages the vertical support surface 32. Releasable fasteners, such as bolts 51 are then inserted in bores 52 in the housing 40 and are threadedly engaged with a threaded bore 53 formed in the housing in order to clamp the roll chock assembly to its associated carrier 14. As the roll chock assembly 39 is lowered from the position shown in Figure 4 to the assembled position shown in Figure I, the splined end 37 of the roll drive shaft 38 is engaged in the splined socket 36 of the pinion 29b.

[0030] Of course, if desired, fixing means other than bolts may be used to secure the roll chock assemblies 39 to their associated carriers 14 and the drive tansmitting connection between the roll drive shaft 38 and the gearbox 25 output element may be other than splined, for example may be a key connection.

[0031] In use, the lateral spacing between the roll members 45 may be adjusted by means of the wedge adjustment assemblies 16 causing sliding movement of each of the carriers 14 along the members 11. This movement is permitted by means of the telescopic shafts 27 between the motors and gearboxes.

[0032] Although axial adjustment of the roll members 45 is not normally required in a roughing mill stand, if axial adjustment is required, shims may be inserted between the carriers 14 and their respective roll chock assemblies 39. In this event, the surfaces 49, 50 of the roll chock assemblies 39 would bear on the support surfaces 31, 32 through the shims.

[0033] When it is desired to exchange a roll, it is merely necessary to disconnect the above described mounting means comprising horizontal and vertical support surfaces and associated bolts or other releasable fasteners and remove, vertically, using a crane or hoist if required, a roll chock 39 assembly and subsequently Insert a new roll chock assembly 39 and reconnect the detachable coupling means as described above with reference to Figure 4.

[0034] If desired, the axes of rotation of the roll assemblies may be other than vertical, such as horizontal, or inclined to the horizontal or verticai; and although in the above example the gearboxes are each driven by a separate motor 28, alternatively a single motor may be used to drive each gearbox from a common drive shaft.

[0035] The present invention provides a rolling mill stand which is compact and has all the advantages of conventional cantilever rolling mill stands but without the disadvantage of the limited rolling load capacity due to the fact that the rolls are not mounted in cantilever manner, but are mounted by means of two bearings, one disposed on each side of the roll.

[0036] Such a roll stand is particularly suitable for use as a roughing mill due to the high rolling load capacity but, of course, it may be used in any desired rolling application, including those where a conventional cantilever roll stand has been used.

[0037] Further, the provision of readily removable roll chock assemblies 39 to carry the roll members 45 facilitates changing of the rolls as they become worn.

Claims

I. A rolling mill stand comprising a frame (10), a pair of roll members (45), means (25) to rotate the roll members to provide a roll pass between the roll members, characterised in that each roll member (45) is carried by its own roll chock assembly (39) which is in turn removably mounted on its own carrier (14), each of the carriers (14) being mounted on the frame (10) for relative lateral sliding movement towards and away from one another, each roll chock assembly (39) comprising a bearing housing (40) having two spaced apart bearing means (44) rotatably mounting one of said roll members (45) therebetween.

2. A stand according to Claim characterised in that the drive means (25) comprises a gearbox for each roll member (45), an output element (36) of the gearbox (25) being detachably connected to the roll member (45) and an input element (26) of the gearbox (25) being driven from a prime mover (28).

3. A stand according to Claim 2 characterised in that the output element (36) of the gearbox (25) extends coaxially with axis of rotation of the roll member (45) and is connected in end-to-end relationship therewith.

4. A stand according to Claim 3 characterised in that the output element (36) comprises a socket in which is detachably received, a roll drive shaft (38) of the roll member (45).

5. A stand according to any one of Claims 2 to 4 characterised in that the gearbox (25) associated with the or each movable roll chock assembly (39) is mounted to move laterally with the carrier (16) the input element (26) of the gearbox (25) being driven from the prime mover (28) through a drive train (27) permitting of said movement.

6. A stand according to any one of the preceding claims characterised in that the axes of rotation of the roll members (45) are generally vertical.

7. A stand according to any one of the preceding claims characterised in that each roll member (45) comprises a roll having, at opposite ends, integral neck portions (46) carried by said bearing means (44).

8. A stand according to any one of Claims I to 6 characterised in that each roll member (45) comprises a roll ring removably mounted on a shaft, end parts of the shaft being carried by said bearing means.

9. A stand according to any one of the preceding claims characterised in that each of the carriers (14) has a generally upwardly facing support (31), the associated roll chock assembly (39) having a part (49) which, in use, engages the support (31) of the carrier (14), the roll chock assembly (39) being detachably carried on the support.

10. A stand according to any one of the preceding claims characterised in that said means which rotate the members (45) includes a drive part (38) attached to or integral with each of the roll members (45) which extends generally downwardly through the lower of the bearing means (44) of the associated roll chock assembly (39).

Drawing