GB2278306A

GB2278306A - Apparatus for measuring rolled strip

Info

Publication number: GB2278306A
Application number: GB9310959A
Authority: GB
Inventors: John Egerton Carter
Original assignee: BRONER GROUP Ltd
Current assignee: BRONER GROUP Ltd
Priority date: 1993-05-27
Filing date: 1993-05-27
Publication date: 1994-11-30
Anticipated expiration: 2013-05-27
Also published as: AU6725294A; WO1994027753A1; GB2278306B; GB9310959D0

Abstract

A shapemeter has a number of rotors 2 mounted side by side on bearings 30 on an arbor 7. Each rotor is formed from a hollow annulus formed from an inner part 14 and an outer part 12, the hollow 15 being between the parts. This arrangement ensures high accuracy in the shapemeter. The parts may be made of titanium. <IMAGE>

Description

Improvements in and relating to Apparatus for Measuring Rolled Strip The present invention relates to apparatus for measuring rolled strip commonly called a shapemeter.

In our International Patent Application Publication No. WO 87/05837 there is described a shapemeter in which a stationary arbor carries several identical rotors which are mounted side by side on the arbor with bearings interposed between the rotors and the arbor. The bearings may be roller or air bearings. Strip material to be measured is wrapped under tension around a part of the outer surface of the rotor typically 100 to 200 of the circumference and sensors measure the load applied to individual rotors so that an instantaneous display of the individual loads indicate the flatness profile or shape of the strip in contact with the several rotors.

In a version of the shapemeter described above in which the rotors rotate on air bearings the rotors are made of solid steel and have an air gap with the arbor of typically 25m.

To ensure the accuracy of the measurement by the meter and to void marking of the strip due to slipping against the rotors, it is important that the rotors have a very low inertia, high dimensional stability under high variations in temperature and a hard surface to withstand wear from the strip. The temperature of the strip is typically up to 1500C and can vary by up to 30"C across the width. hence it is normal for the rotors to reach different temperatures. Differential expansion of the outside diameter of the rotors will present a non-uniform surface to the strip which will result it a false reading. Axial expansion of each rotor relative to the arbor can result in interference between the rotors which will affect the results.Expansion of the inside diameter of the rotors will increase the air gap which reduces the stiffness of the bearings.

It is an object of the invention to reduce the problems caused by expansion and to provide increased accuracy of measurement in a shapemeter.

According to the invention there is provided a shapemeter having an arbor on which are mounted side by side a plurality of rotors with bearings interposed between the arbor and rotors characterised in that each rotor comprises an inner cylindrical part having an inner surface facing towards the arbor and an outer cylindrical part having an outer surface facing away from the arbor and a hollow gap between the inner and outer surface.

The hollow gap reduces the total inertia of the rotor suitably by as much as 75% as compared with a solid rotor and the gap acts as a heat barrier to reduce heat being conducted from the strip being measured to the arbor.

Hence bearings clearances may be kept stable. A further improvement in reducing heat conduction results when the gap is evacuated.

When air bearings are used between the rotors and arbor, cooling results from the continual purging of air between the arbor and rotors which spills over side walls of the rotors. Some cooling may result from the outer surface of the rotors by radiation and convection whilst rotating.

By constructing the rotors with their walls of no greater than 5 mm and preferably 2-3 mm it is possible to keep rotor inertia to a minimum whilst possibly assisting in the cooling effect of air from air bearings.

In a preferred embodiment the inner and outer cylindrical parts are made separately and are assembled in an axial direction. Abutment surfaces for the parts to abut in the axial direction are provided which prevent through sputtering of electron beam particles into the evacuated gap, when the parts are welded together by electron beam welding. The abutment surfaces on one side of the rotor are radially offset from the abutment surfaces on the other side of the rotor in order to assist assembly. In order to keep the inertia to a minimum the rotor parts are made from titanium which is hard, has a low coefficient of expansion when compared with steel but is expensive. The expense is reduced by the provision of the gap reducing the volume of the material. The construction with the thin wall section minimises the transfer of heat through to the inside diameter.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 shows diagrammatically a side view of a shapemeter, Figure 2 is a part diametral cross section of a shapemeter of Fig. 1, and Figure 3 is a part of the cross section of Fig. 2 to an enlarged scale showing assembly of the rotor parts.

Referring to the drawings a shapemeter, indicated generally at 1 comprises a series of rotors 2 carried between end housings 3 carried by supports 5 on a carrier beam 6.

The rotors 2 are mounted on a stationary arbor 7 formed with a central bore 8.

As shown in Fig. 3 each rotor is formed of an outer cylindrical part 11 having an outer surface 12 facing away from the arbor and an inner cylindrical part 13 having an inner surface 14 facing towards the arbor. Between the outer and inner surfaces 12,14 is a gap 15 which when the parts are assembled is evacuated. The parts 11 and 13 are made of titanium in order to keep the inertia as low as possible. The rotor diameter is 229 mm and is 50 mm wide the wall thickness of the rotor parts is 3 mm and the diameter of inner surface 14 is 200 mm. However, the rotor dimension may be varied for other examples.

Rotor part 11 is formed with an inner flange 18 onto which an outer flange 20 of rotor part 13 abuts when assembled.

Similarly part 13 is formed with an inner flange 22 onto which an outer flange 24 or part 11 abuts when assembled.

The flanges provide abutment surfaces, those on one side being offset from those on the other side of the rotor so that the rotor parts can be assembled with flanges 18 and 22 providing abutment surfaces to prevent through sputtering of electron beam particles in the evacuated gap 15 when the parts are welded together by electron beam welding at 26 and 28.

An air bearing is provided between inner surface 14 and arbor 7 at 30 supplied with air from within the arbor by means of ducts 32.

Claims

1. A shapemeter having an arbor (7) on which are mounted side by side a plurality of rotors (20) with bearings (30) interposed between the arbor and rotors characterised in that each rotor comprises an inner cylindrical part (13) having an inner surface (14) facing towards the arbor and an outer cylindrical part (11) having an outer surface (12) facing away from the arbor and a hollow gap (15) between the inner and outer surface.

2. A shapemeter as claimed in claim 1 wherein the hollow gap (15) comprises an hermetically sealed area between the inner and outer cylindrical parts (13,11)

3. A shapemeter as claimed in claim 2 wherein the hermetically sealed area (15) is evacuated.

4. A shapemeter as claimed in any one of claims 1 to 3 wherein said rotors (2) are provided with air bearings (3) interposed between the arbor and rotors, said rotors being so arranged that air from the air bearing spills over and past side walls (20,24) of the rotors.

5. A shapemeter as claimed in any one of claims 1 to 4 wherein said rotors (2) are provided with air bearings (30) said arbor being provided with means (32) to supply air from within the arbor to a bearing gap between the arbor (7) and said inner surface (14) facing towards the arbor.

6. A shapemeter as claimed in any one of claims 1 to 5 wherein the rotors (2) are formed from titanium.

7. A shapemeter as claimed in any one of claims 1 to 6 wherein the inner and outer cylindrical parts (13,11) are arranged to be assembled axially an abutments surface (18) on the outer part (11) being radially offset from an abutment surface (22) on the inner part 13.

8. A shapemeter as claimed in claim 7 wherein the abutments surfaces are formed on annular flange portions extending inwardly from the outer part and outwardly from the inner part, further abutment surfaces for engagement with the flange portions being formed on an outwardly extending portion of the inner part and inwardly extending portion of the outer part, the outer flange portion being radially greater in extent at its inner extremity than the inner flange portion and its outer extremity.

9. A shapemeter as claimed in any one of claims 1 to 8 wherein the walls of the rotor are no thicker than 5 mm and preferably between 2 and 3 mm thick.

10. A shapemeter substantially as described with reference to the accompanying drawings.