This invention relates to a shapemeter for continuously detecting and indicating the shape of metallic strips during a rolling operation. The invention also provides a rotor module for such shapemeter.

In the rolling of metallic strip "shape" means a variation in width-wise tension when the strip is held in lengthwise tension. Thus "shape" refers to deviations of flatness of the strip in more than one direction. Poor flatness or "shape" results from imperfect rolling at an earlier stage and, unless remedial action is taken, is manifested in the finished product. By using a shapemeter lack of flatness may be detected and remedial action taken during the rolling operation.

A shapemeter usually has a _% number of concentric rotary sleeves arranged transversely to the passline of the strip and engaged under tension by the moving strip which is arranged to have a small "wrap" around the sleeves. Variations in shape are detected by sensing the load applied to individual sleeves, an instantaneous display of these individual loads indicating the flatness profile or shape of the strip then in contact with the shapemeter. Signals from the shapemeter representative of these individual loads may be used to control automatically the rolling operation, as by varying roll profile, or the degree and location of bad shape as indicated by the display may be interpreted to effect manual control of the rolling operation.

Numerous designs of shapemeters have been proposed in the past and some, such as that described in U.K. patent 1160112 are in successful use. In most earlier constructions the sleeves are carried on a mandrel and supported on air or roller bearings and the relative

deflections of the sleeves are detected either by sensing changes in air pressure or by the use of other forms of load detector.

All existing shapemeters require very high tolerances to be maintained during construction resulting in very expensive instruments. Furthermore most current designs limit the minimum width to which a rotor can be manufactured thus limiting the number of rotors for a particular axial length of shapemeter and this, in turn, limits the resolution of measurement.

It is an object of the present invention to provide a shapemeter of simplified construction that does not require high tolerances during manufacture and that enables narrow rotors to be constructed. A further object is to provide an improved rotor module for such a shapemeter.

According to one aspect of the present invention there is provided a rotor module for a shapemeter comprising a central arbor, at least one bearing on the circumferential surface of the arbor, a ring rotatable on the bearing, an outer cylinder supported at three or more locations on the ring to hold the cylinder concentrically of the rotor and means carried by the arbor to co-operate with the inner surface of the cylinder to detect ^' deflections thereof at positions in register with said means and between said locations in order to provide output signals representative of such deflections. Signals provided by said means at the support locations may constitute reference signals. Preferably the arbor is hollow. Ideally two spaced apart bearings are provided on the arbor to be engaged by separated rings on the cylinder, said means co-operating with the inner surface of the cylinder between the rings. The outer cylinder may be located by circumferentially corresponding arcs of the

circumference engaging the rings and there are preferably four such arcs. More than one independently rotatable cylinder may be mounted on a single arbor.

According to another aspect of the present invention there is provided a shapemeter comprising a plurality of rotor modules according to the preceding paragraph having their arbors joined together so that the cylinders of each module are concentric.

The above and other aspects of the present invention will now be described by way of example with reference to the accompanying drawings in which:-

Figure 1 is a part sectional side view of a shapemeter; and

Figure 2 is a section on the line II-II to a larger scale.

Referring to the drawings a shapemeter, indicated generally at 1 , comprises a series of rotor modules 2 carried between end plates 3 having trunnions 4 carried by supports 5 on a carrier beam 6.

Each module 2 has a stationary arbor 7 formed with a central bore 8, a pair of bearings 9, rings 10 rotatable on the bearings and a rotatable outer cylinder 11. As shown in Figure 2 the outer cylinder 2 is formed with four matching pairs of arcs 12 (Figure 2) equispaced around its inner surface 13 and respectively closely engaging the rings 10. Thus at the position of the arcs 12 the cylinder 2 is firmly supported whereas between these arcs it is unsupported.

A plurality of modules are joined axially by bolts 14 passing through the end plates 3 , and the arbors 7, so

that the assembly is rigidly mounted with each outer cylinder separately rotatable. It will here be understood that the axial lengths of each cylinder 11 are slightly less than the axial lengths of the arbors 7 so that the cylinders are freely deflectable.

As shown in Figure 2 the shapemeter is mounted so that a rolled strip 15 passes under tension over the cylinders 11. Each cylinder is therefore subjected to a vertical load and the unsupported part of each cylinder 11 deflects proportionally with this load. The deflection is measured by sensors such as 16 carried by each arbor 7. The sensors may, for example, detect a change in capacitance between the inner surface 13 of the cylinders 11 and a plate 17. The outputs of all the sensors are carried externally of the shapemeter by wires 18.

As those sections of each cylinder 11 supported by the arcs 12 pass over the plate 17 there will be no deflection so that a constant reading for all modules will be obtained. Changes in temperature or humidity will affect the readings by changes in the dialectic constant of the capacitor and by expansion. The supported and unsupported sections will be equally affected so that measurement from the supported sections can be used as a reference.

Although four arcs 12 have ^' been shown three or -more would be possible. Furthermore although two bearings 9 rings 10 and arcs 12 have been described each cylinder 11 could have only a single set of arcs supported on a single, off centre, ring.