GB2031771A

GB2031771A - Rolling mill guide

Info

Publication number: GB2031771A
Application number: GB7932363A
Authority: GB
Original assignee: HOVERDALE ENG Ltd
Current assignee: HOVERDALE ENG Ltd
Priority date: 1978-09-19
Filing date: 1979-09-18
Publication date: 1980-04-30
Also published as: GB2031771B

Abstract

A mill guide 1 is disposed between rolling mill stands to guide the edge of a strip 4 while supported for movement on table rollers 2, 3, and has two longitudinal slots 6 in each of which two flat longitudinal holders 11 can be received in a vertical plane and end-to-end in longitudinal alignment. Each holder 11 has a plurality of spaced ceramic pads 17 dovetailed therein, the dovetail axes extending vertically. The pads 17, which are made of an alumina ceramic material, provide an exceptionally wear-resistent surface for guiding the hot strip 4. When the pads on the holders in one of the slots 6 become worn, the mill guide 1 can be turned through 180 DEG to present the pads on the holders in the slot 7 for guiding the strip 4. <IMAGE>

Description

SPECIFICATION Rolling mill guide This invention relates to strip rolling mills, and in particular to mill guides for guiding strip being rolled as it passes between rolling mill stands.

During the rolling of steel strip the length and hence speed thereof progressively increases as the thickness is reduced by rolling, reaching speeds of the order of 20 m/sec before coiling. The strip is rolled hot, commonly at a temperature of about 800"C, and friction maintains and even increases this temperature. The result is that the mill guide surfaces are subject to arduous wear conditions, particularly as they are usually of mild steel. Other harder-wearing materials, and expedients such as a sprayed-on ceramic coating, have been tried but without conspicuous success.

The object of the invention is to provide a mill guide with an exceptionally wear-resistant surface in a practicable and cost-effective manner and which, moreover, is replaceable when necessary without replacement of the mill guide as a whole.

According to one aspect of the invention, in a strip rolling mill the strip while being rolled is guided between mill stands on a guide surface provided by a plurality of spaced ceramic pads mounted on the mill guide. The ceramic material is chosen to be sufficiently heat resistant to withstand the rolling temperature, and a suitable material has proved in practice to be that sold under the trade name DERANOX 975 manufactured by Andaman 8 Ryder Limited.

The pads may be fixed to holders which are in turn fixed to the mill guide. The pads may be clamped to the holders, but it is preferred that they are dovetailed into the holders with the dovetail axes disposed laterally of the longitudinal axis of the mill guide. In one preferred embodiment two spaced and parallel pairs of holders are mounted in milled longitudinal slots in the mill guide, each holder carrying at least one ceramic guide pad dovetailed into the holder, the two holders of each pair being arranged end to end in longitudinal alignment. This provides an arrangement in which the mill guide can be turned through 1 80 C when the pads in one pair of holders are worn, thereby bringing the pads of the other pair into use.

According to another aspect of the invention, a guide pad assembly for a strip rolling mill comprises a holder for fixing to the guiding surface of a mill guide and which carries at least one ceramic guide pad with a smooth upper guide surface and inset into the holder.

A smooth surface for the pads is essential not only to reduce friction but also to avoid fracture of the ceramic material, and to this end the pads may be diamond ground.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings. In the drawings: Figure 1 is a side view of a mill guide formed to receive guide pad assemblies according to the invention, the mill guide being shown partly fitted with such assemblies; Figure 2 is a cross-section taken on the line Il-Il in Fig. 1; Figure 3 is a plan view of a holder of one guide pad assembly; Figure 4 is a side view of the holder, showing one guide pad fitted; Figure 5 is a plan view of one guide pad; and Figure 6 is a side view of the pad.

The rolling mill is of conventional form with the mill guide 1 fitted between rolling stands to guide thè strip being rolled while passing between the stands. The fuide 1 is fitted at one side of two spaced driven table rollers, indicated in broken lines at 2 and 3, a short length of the guided strip being indicated in broken lines at 4. Arcuate edge cut-outs 5 in the mill guide 5 provide clearance for the stepped table rollers 2 and 3, similar cut-outs 5 being provided in each edge so that the guide can be inverted by turning through 180 .

Two longitudinal slots 6 and 7 of rectangular configuration are milled in the guiding side surface of the mill guide 1. These slots extend throughout the full length of the guide 1 and are respectively disposed adjacent the side edges of the guide, and they are arranged so that the corresponding edge of the strip 4 runs in the region of the centre-line of the slot 6. Along the slot centre-lines the mill guide is provided with two rows of tapped fixing holes at positions 8 for fixing guide pad assemblies in the slots 6 and 7, two such assemblies 9 and 10 being shown fixed in the slot 6 in Fig.

1.

A guide pad holder 11 of the assembly 9 is shown in Figs. 3 and 4, the holders having chamfered corners such as 1 3 to match the cut-away corners of the mill guide 1. The holder 11 has an arcuate edge cut-out 1 3 which matches the corresponding edge cutout 5 of the guide 1. It will be appreciated that the four holders such as 11 are correspondingly handed, according to the side edge provided with the chamfer 1 2 and cutout 1 3. Each holder is a close lateral fit in the corresponding slot 6 or 7 and is exactly half the length of the mill guide 1, so that a pair of holders can be fixed end to end in the slot 6 and a similar pair in the other slot 7.At the outer, i.e. corner chamfered, end the holders have an inclined or chamfered lead surface as shown at 14 and countersunk screw fixing holes at 1 5 for alignment with the tapped holes 8 in the guide 1.

Each holder such as 11 has three spaced and identical lateral dovetail grooves 16, each of which receives a complementary dovetail ceramic insert of pad such as 17, one of which is shown in position in Fig. 4. Each pad 1 7 has a smooth guide surface, for example a diamond ground surface, which stands slightly proud of the surface of a holder such as 11 to which it is fitted. The back faces of the pads 1 7 are accurately flat as are the base surfaces of the grooves 1 6 to provide adequate support for the inherently frangible ceramic material.

The pads such as 1 7 are equal in length to the width of the holders such as 11, and hence when fitted they are retained against movement by the edges of the grooves 6 and 7 in the mill guide 1. It will be appreciated that in use only the pads associated with the lower guide slot (6 in Fig. 1) are subject to wear, so that when they are worn the guide 1 can be inverted by turning through 180 to bring the pads associated with the other slot 7 into use.

In a specific arrangement as described and illustrated, the ceramic pads have a length (in the direction of the dovetail axis) of about 127.0 mm, a width of about 76.2 mm and a thickness of about 7.92 mm. The ceramic material is the aforesaid DERANOX 975, which is an alumina ceramic, and the dovetail angle is 70 . When inserted into a holder the upper surface of the pad stands slightly proud by about 1. 32 mm which is the amount available for wear before the guide 1 is turned round to bring the fresh pads into use.

Claims

1. A strip rolling mill comprising a plurality of rolling mill stands and a mill guide for guiding strip being rolled as it passes between the rolling mill stands, the mill guide having a guide surface provided by a plurality of spaced ceramic pads mounted on the mill guide.

2. A strip rolling mill as claimed in claim 1, wherein the ceramic pads are fixed to holders which are in turn fixed to the mill guide.

3. A strip rolling mill as claimed in claim 2, wherein the ceramic pads are clamped to the holders.

4. A strip rolling mill as claimed in claim 2, wherein the ceramic pads are dovetailed into the holders with the dovetail axes disposed laterally of the longitudinal axis of the mill guide.

5. A strip rolling mill as claimed in claim 4, wherein two spaced and parallel pairs of holders are mounted in longitudinal slots in the mill guide, each holder carrying at least one ceramic guide pad dovetailed into the holder, the two holders in each paid being arranged end-to-end in longitudinal alignment.

7. A guide pad assembly for a strip rolling mill, comprising a holder for fixing to the guiding surface of a mill guide, the holder carrying at least one ceramic guide pad which has a smooth upper guide surface and which is inset into the holder.

8. A guide pad assembly as claimed in claim 7, wherein the said upper guide surface of the or each ceramic guide pad is diamond ground.

9. A guide pad assembly as claimed in claim 7 or 8, wherein the or each ceramic guide pad is made of alumina ceramic material.

1 0. A guide pad assembly as claimed in claim 7, 8 or 9, wherein the or each ceramic guide pad is dovetailed into the holder.

11. A strip rolling mill substantially as hereinbefore described with reference to the accompanying drawings.

1 2. A guide pad assembly for a strip rolling mill, substantially as hereinbefore described with reference to the accompanying drawings.