GB2197811A

GB2197811A - Rolling mill stand

Info

Publication number: GB2197811A
Application number: GB08626898A
Authority: GB
Inventors: Dennis Stubbs; Keith Birch
Original assignee: Hille Engineering Ltd; Hille Engineering Co Ltd
Current assignee: Hille Engineering Ltd; Hille Engineering Co Ltd
Priority date: 1986-11-11
Filing date: 1986-11-11
Publication date: 1988-06-02
Anticipated expiration: 2006-11-11
Also published as: GB8626898D0; GB2197811B

Abstract

A rolling mill stand comprises a pair of rolls supported at their ends in bearing chock assemblies 1, the assemblies being located in frames 8 and, in each frame, the assemblies are coupled together by a pair of shafts 2 each having right- and left- hand threads meshing in nuts 3, so that, on rotation of the shafts, the two assemblies are caused to move towards and away from each other, thus adjusting the roll gap. A gearbox structure 5 is mounted above or below the rolls for rotating the shafts 2. <IMAGE>

Description

ROLLING MILL STAND This invention relates to a rolling mill stand for rolling rod, bar and metal sections.

According to the present invention, a rolling mill stand comprises a pair of parallel rolls each supported at its ends in separate bearing chock assemblies, the two bearing chock assemblies at one corresponding end of the rolls being located in a window defined by a first rigid frame, and the two bearing chock assemblies at the other corresponding end of the rolls being located in a window defined by a second rigid frame, each frame being formed in part by a gearbox structure having a pair of vertical rotatable output shafts extending therefrom into the window, each shaft having a portion of right-hand screw thread thereon which engages with a fixed nut in one of the bearing chock assemblies in the window to support the assembly and a portion of left-hand screw thread thereon which engages with a fixed nut in the other bearing chock assembly in the window to support said other assembly whereby, on rotation of the output shafts, the two assemblies in the window are caused to move towards or away from each other.

Advantages of this rolling mill stand are that it has a short stress pass, it is of high stiffness but the frames do not have to withstand the rolling loads and the roll gap is adjusted about the pass-line when the rolls are moved towards or away from each other.

In order that the invention may be more readily understood, it will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front elevation, partly in section, of a rolling mill stand in accordance with the present invention; Figure 2 is a section on the line Z-Z of Figure 1, Figure 3 is a side elevation; and Figure 4 is a partial plan.

A pair of parallel rolls are supported at their ends in separate bearing chock assemblies 1. The chock assemblies at one corresponding end of the rolls are located in a window in a frame 8 and the bearing hock assemblies at the other corresponding end of the rolls are located in a window of a second frame 8.

Four shafts 2 each have a portion of right-hand and a portion of left-hand screw thread. In each bearing chock assembly there are a pair of nuts 3 (only one being shown in Figure 1). The two nuts in one of the bearing chock assemblies mesh with one of the thread portions on the two shafts 2 and the two nuts 3 in the other bearing chock assembly mesh with the other thread portion on the shafts. There is a minimum length of shaft between the nuts in order to minimise the tensile deflection between the bearing chock assemblies. The two shafts 2 which extend into each window are the output shafts of a gearbox 5 and, within the gearbox, there are spur gears 4 which cause the two output shafts to rotate in unison.The output shafts associated with one of the frames 8 on the drive side of the rolling mill are connected together by worm gears 6 and shafts 6A to corresponding worm gears on the output shafts of the work side chock assemblies.

Provision is made for de-coupling the shafts connecting the worm gears to allow the rolls to be levelled.

Springs or hydraulic pistons 7 are provided to balance the weight of the top roll assembly 1 and to take out clearances in the interfaces between the nuts and the screw threaded portions of the shafts.

The gearbox 5 forms part of each frame 8 and the bearing chock assemblies and the rolls are suspended from the gearbox by'way of the shafts 2.

Hence, the gearbox acts as an "earth point" so that, as the output shafts are rotated, the rolls move equally about the pass-line.

In use, when a workpiece is passed between the rolls, the rolling loads try to force the rolls apart and the force is taken through the nuts and the threaded portions on to the shafts 2. Only the threaded portions of the shaft and the part of the shaft between the threaded portions are subjected to the rolling load. The gearbox and the output shafts are of sufficient structural rigidity to be able to take the weight of the rolls and the bearing chock assemblies.

The portions of the shafts which are located between the bearing chock assemblies may be enclosed by screens 11 or the like in order to prevent dirt and other foreign bodies from becoming lodged in the screw threads.

The two frames 8 are connected to a base plate 12 which is made in two parts and which are bolted together. The bearing chock assemblies 1 are provided with wings 9 which extend into slots formed in the frames 8 to prevent the bearing chock assemblies and hence the rolls from being displaced in the axial direction of the rolls. However, a device 10 is fitted to at least one of the rolls to enable it to be moved axially with respect to its bearing chock assemblies.

Any forces in the direction of rolling caused by tensile or compressive stresses in the workpiece are taken by the frames 8. Load cells 13 may be positioned in the housings adjacent the chocks 1 on either side of the roll axis. The chocks bear against the load cells and the load cells give an indication of the forces in the direction of rolling.

When it is necessary to remove the rolls from the frames, the wings 9 may be removed from the slots in the frame and the gearboxes, output shafts, bearing chocks and rolls may be moved axially of the rolls out of the frames. Alternatively, however, the two frames can be separated by unbolting the base plate. The two frames are separated whilst supporting the rolls. The rolls only are removed, the chocks remaining in the frames. The rolls are mounted in cylindrical roller bearings to facilitate this.

Although in the figures the gearbox has been shown as forming the top part of the frames 8 with the rolls positioned below the gearbox, it will be understood that the structure can be reversed so that the gearbox positioned below the rolls and the output shafts 2 extend upwardly from the gearbox into the window and the rolls are supported on the shafts.

Claims

Claims:

1. A rolling mill stand comprising a pair of parallel rolls each supported at its ends in separate bearing chock assemblies, the two bearing chock assemblies at one corresponding end of the rolls being located in a window defined by a first rigid frame, and the two bearing chock assemblies at the other corresponding end of the rolls being located in a window defined by a second rigid frame, each frame having a gearbox structure with a pair of vertical rotatable output shafts extending therefrom into the window, each shaft having a portion of right-hand screw thread thereon which engages with a fixed nut in one of the bearing chock assemblies in the window to support the assembly and a portion of left-hand screw thread thereon which engages with a fixed nut in the other bearing chock assembly in the window to support said other assembly whereby, on rotation of the output shafts, the two assemblies in the window are caused to move towards or away from each other.

2. A rolling mill stand as claimed in claim 1, in which the gearbox structures are at the top of the frames.

3. A rolling mill stand as claimed in claim 1 or 2, in which the output shafts at one rigid frame are coupled mechanically to those at the other rigid frame so that all the shafts rotate in unison.

4. A rolling mill stand as claimed in any preceding claim, in which each bearing chock assembly is prevented from being moved relative to the frame in the direction parallel to the axial length of the rolls.

5. A rolling mill stand as claimed in any preceding claim, in which the two frames are mounted on separate base plates which are removably secured together.

6. A rolling mill stand as claimed in any preceding claim, in which load cells are located between each bearing chock assembly and the frames to indicate forces acting therebetween in the direction of rolling.

7. A rolling mill stand substantially as hereinbefore described with reference to the accompanying drawings.