GB2104221A - Shapemeter - Google Patents

Abstract

A strip shapemeter is formed by an axial sequence of bearing units (15) mounted about a stationary mandrel (12). Each bearing unit consists of an outer sleeve (24) supported by a ball race (25) from a stationary inner sleeve (23). The mandrel (12) carried a load detector for each bearing unit, that detector engaging the inner sleeve (23) which is loaded on to the detector by a piston-cylinder assembly (37) arranged between the mandrel and the inner sleeve. All the piston-cylinder assemblies (37) are supplied from a common duct (40) so that the bearing units are equally loaded. Seals (30) are provided between adjoining faces of the bearing units. <IMAGE>

Description

SPECIFICATION Shapemeter This invention relates to shapemeters for material in elongate form, hereinafter referred to as "strip". A shapemeter is an instrument for continuously detecting and indicating the flatness of strip, revealed by variations in width-wise variations in strip tension when the strip is held in lengthwise tension. In metal rolling, 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 the use of a shapemeter, lack of flatness may be detected and remedial action taken to improve the shape during rolling.

A shapemeter usually consists of a sequence of rotary sleeves which are arranged transversely to the passline of the strip and which are engaged by the tensioned moving strip. Variations in shape are detected by sensing the loadings applied to the individual sleeves by the strip tension, a display of the instantaneous loadings on the sleeves indicating the flatness profile of the strip then in contact with the shapemeter. The signals from the shapemeter may be used to control automatically the rolling operation, as by varying roll profile, or simply to displaythe degree and location of bad shape in order that the rolling operations may be controlled manually.

There have been a number of designs of shapemeters proposed in the past and some, such as that described in British patent specification No.

1,160,112, are in successful use today. In most, the sleeves are carried on a mandrel supported on air bearings or roller bearings and the relative deflections of the bearings are detected either by sensing changes in air pressure or by the use of load cells of some form. All have required the diameters of the sleeves to be equal to a degree of tolerance an order better than the accuracy of sensing the transmitted loads; otherwise inaccurate readings arise. As a consequence, shapemeters in current use are expensive.

A further disadvantage of present day shapemeters is that, because of their construction, the leads from the load sensors and other connections are carried out through one or both of the mandrel ends, with the result that the shapemeter cannot be located within the housings of a multi-stand rolling mill and must be positioned in the limited space between stands where it is vulnerable and where it occupies space normally required for other purpses.

The present invention provides a shapemeter construction in which the accuracy of the outside diameters of the sleeves may be less than in previous constructions so that economy in cost may be achieved without necessarily losing accuracy of readings.

According to the invention, a shapemeter comprising: a mandrel; a series of bearing units arranged in axial sequence about the mandrel but capable of radial adjustment relative to the mandrel, each bearing unit having an outer sleeve supported by an inner sleeve through a bearing race and designed to be engaged and rotated by the strip; and, for each bearing unit, at least one load detector unit seated on the mandrel and lying between its bearing unit and the mandrel, the load detector units being substantially aligned axially adjacent the intended area of contact of the strip with the bearing units.

The shapemeter of the invention is characterized by the radial width of the bearing units being substantially the same for all such units and the radial depth of the load detector units being substantially the same for all such units, and by having hydraulic means arranged to load each bearing unit against its load detection unit and connected to a common supply duct for fluid under pressure, whereby all the bearing units are loaded equally on to their detection units and the exteriors of all the bearing units are equally spaced from the mandrel at the area of strip contact regardless of variations in the diameters of the bearing units.

By virtue of the hydraulic means, the outside diameters of the bearing units no longer need to be closely constant, provided that the difference between the inner and outer diameters of each bearing unit is kept within close tolerance so that the distance between the centre of the mandrel and the exterior of the bearing unit at the location of the load detector unit or units is substantially equal for all units. The hydraulic means ensure that all bearing units are properly positioned relative to their load detector or detectors regardless of possible variations in their outside diameters and that all detectors give the same reading when the strip has constant gauge over its width.

Furthermore, the hydraulic means, being supplied from a common supply, enable all the bearing units to be loaded simultaneously to give them their correct positioning, and facilitate assembly and disassembly of the shapemeter for servicing.

The invention will be more readily understood by way of example from the following description of a shapemeter in accordance therewith, reference being made to the accompanying drawings, in which Figure 1 shows the shapemeter in end view, Figure 2 is a section on the line A-A of Figure 1 showing one end of the shapemeter, Figure 3 is a radial section of the shapemeter, Figure 4 is similar to Figure 3, but illustrates a modification, Figure 5 is a development of the ball cage of one of the bearing units, and Figures 6 and 7 illustrate a preferred form of bearing, after assembly and before it is axially compressed, respectively.

The shapemeter shown in the drawings consists basically of a fixed mandrel 12, having at each end a square-section neck 13 enabling the mandrel to be mounted in a frame, and a series of identical bearing units two of which are shown in Figure 2 at 15 and which are carried in sequence about the mandrel.

The mandrel 12 has a constant cross-section between its ends, having two part-cylindrical locating surfaces 17 (Figure 3) just below the horizontal centre line, and elsewhere a series of flats 18A-H.

Uppermostflat 18A includesaslot 20, the surface of which is accurately ground at a fixed distance from the mandrel axis and which receives load cell units to be described.

Each of the bearing units 15 consists of an inner sleeve 23, which has an inner diameter only slightly greater than that of the cylindrical surfaces 17 of the mandrel, an outer sleeve 24, and an interposed ball race 25 having a cage 26 locating the balls 27. A roller race may be employed in place of the ball race 25. The bearing units are arranged contiguously along the mandrel and are held axially by retaining rings one of which is shown at 28. The ends of each outer sleeve 24, each race 26 and the surface of each ring 28 facing the bearings are coated with PTFE to reduce friction. One end of each of the inner and outer sleeves 23 and 24 has an annular recess 29 which receives a ring seal 30 engaging against the sleeve of the adjacent bearing unit or against a retaining ring 28.

Each bearing unit 15 is supported buy a load cell unit 32 secured in the slot 20 of the mandrel. The load cell units have an accurately uniform depth; for example, as shown, each unit may consist of a load cell 33 secured on a block 34 which is machined after attachment to the load cell to give the composite unit a prescribed depth regardless of variations in the thickness of the load cell. Each bearing unit is preloaded on to its load cells by a pair of hydraulic piston and cylinder units 36 disposed in recesses in flats 18D and 18F and on opposite sides of the vertical axial plane, with the pistons 37 engaging against the inner sleeve 23. A pocket 38 is formed in the mandrel above each unit 36 and communicates with an axial passage 40 which is common to all bearing units.When fluid under pressure is supplied to passage 40 all bearing units 15 are equally preloaded on to their load cells 33 which give equal signals through their leads 42. Leads 42 pass to conduits located in the relatively wide passages formed between flats 18C, 18G and the bearing units.

The inner sleeves 23 are held against rotary movement by keys 47 secured in keyways in the sleeves by screws 48 and located in a keyway in the mandrel 12.

Each neck 13 is secured in a collar 50 having attached to it an ear unit such as that shown at 51 or 52. Each ear unit encloses a passage 53 extending from opening 54 aligned with the passage along the flats 18C and 18G to an exit 55 directed towards the opposite end of the mandrel externally of the bearing units. The passage 53 receives a liner 56.

The cables from the two cable conduits are led through the passage 53, being guided therein by the liner 56 and thence out of the shapemeter. If desired the leads can be connected to an electrical coupling allowing the shapemeterto be readily detached from its electrical equipment for removal from site as shown at the right hand side of Figure 2; or, the leads may be threaded through a reinforced flexible tail as shown at the left hand side of that Figure.

Similarly the fluid supplies can be connected to the passage 40 via a collar unit attached to the mandrel at the same end.

The strip, the flatness of which is to be detected, passes under lengthwise tension over the shapemeter, the top surface of which is slightly above the passline, and engages the bearing units 15 over a small arc centred over the line of load cell units 32.

Provided that the strip has width-wise flatness, the strip tension is uniform across its width and each bearing unit 15 is equally loaded by the strip tension; the bearing units 15 are deflected equally and the load cells give equal signals through their leads 42 to display and/or control equipment (not shown). If, on the other hand, the strip has imperfect flatness, the lengthwise strip tension varies across the width and loads the bearing units 15 unequally, so that the load cells of the various units 15 give differing signals, which, when displayed, show the tension variation at the various locations across the strip corresponding to the positions of the bearing units 15. The sensed variations may then be used to control manually or automatically the rolling operation to improve the strip flatness.

The sleeves 23 and 24 can be manufactured without difficulty to uniform thickness within close tolerances. As the balls 27 or the rollers if alternatively used are of constant diameter and the load cell units 32 are made with uniform depth as described, the separation of the outer surfaces of the outer sleeves 24 from the axis of the mandrel is equal for all units 15 to close tolerance. As the surfaces of the units 15 contacted by the strip are at constant height, the same signal is given by the load cells of each and every unit 15 when the strip has ideal flatness. From that point of view, the diameters of the sleeves 23,24 are immaterial provided they are within broad tolerances and care need not be taken to ensure that the outer diameters of the outer sleeves 24 are kept within close tolerances.As it is easier to hold the thickness of the sleeves within tolerance than to do so for the diameters, the costs of machining and of the shapemeter as a whole are reduced.

Because the electrical connections and other services leave the end collar in the direction towards the other end of the shapemeter roll, space for the leads beyond the ends of the collar need not be reserved.

As a result the shapemeter roll may be located within the confines of a rolling mill housing. In previous shapemeter designs that has not been possible either because of the need to have a siip ring unit on the end of the assembly or because of the number of pipes needing to be brought out axially from that end.

The shapemeter illustrated by Figure 4 is generally similar in construction and principle to that described, except in the following respects: there is now a single hydraulic piston and cylinder unit 36A for each bearing unit 15 arranged in a radial recess 60 and diametrically opposite to the load cell unit 32.

The keys 47 are dispensed with, their function being performed by enlarged ends 61 of the pistons of the units 36A, which ends are received in complementary recesses 62 in the inner sleeves 23. Further, part-cylindrical locating surfaces 17A, which locate the bearing units properly with respect to the mandrel without obstructing minor adjustment of the bearing units in the vertical direction of Figures 3 and 4, are substantially longer than the corresponding surfaces of Figure 3.

The number of bearing units 15 employed for a unit strip width can be varied according to requirements. The axial length of those shown in Figure 2 is relatively small in order that the strip shape may be precisely detected and indicated. However, if a less precise indication is required, the axial length of each bearing unit may be increased and the number of units correspondingly decreased; in the latter case two axially spaced load cell units 32 may be provided for each bearing unit.

Although a particular form of sealing elements 29 is illustrated in Figure 2, other suitable design of seals may be employed if desired.

Figure 5 shows a development of the cage of one of the ball races 25, the location of each ball in the cage being represented by an "X". Unlike commonly produced ball races in which the balls are arranged in a series of similar helices about the axis of the race, and which tend to be urged axially by screwing action when rotation ofthejournalled member occurs, the balls depicted in Figure 5 are arranged in two opposed sets of helices, arranged on opposite sides of the circle line C midway between the edges E of the cage. In other words, the helices on opposite sides of the line C diverge oppositely away from that line in the direction of rotation.On rotation of the outer sleeve 24 the opposed helical arrangement of the balls results in there being no significant resultant axial thrust on the cage which tends to remain axially stationary within the sleeves 23 and 24.

As an alternative to the ring seals 30, it is preferred to employ the seal and thrust bearing units shown in Figures 6 and 7.

In Figures 6 and 7, each bearing is shown as comprising the outer sleeve 24, 24a, the inner sleeve 23, 23a, and a bearing roller race 25. Under normal working conditions a gap 70 exists between adjacent bearings. Substantially rigid anti-friction face bearing rings 71,72 are located between the outer and inner sleeves 24, 23 respectively, being positioned within recesses 73,74 formed in those sleeves 24, 23.

The anti-friction face-bearing rings are as shown in the drawings with comparatively shallow annular recesses 75,76 in that face which is adjacent the next bearing, and somewhat deeper recesses 77,78 on the face opposite the recesses 75,76. Further recesses 80, 81 are formed as shown in the outer and inner sleeves 24, 23 and within the recesses 77,78, 80 and 81 are fitted annular sealing rings 82,83,84 and 85, constituting resilient means biasing the bearing rings into contact with sleeves 23a, 24a.

The sealing rings are compressible, being made for example of cellular rubber or neoprene as shown, or being hollow, e.g. tubular. The bearing rings 71,72 are preferably of a low-friction type bearing material, for example bronze, filled or graphite-impregnated bronze, cast iron, carbon or any available plastics material which will withstand the rubbing speed existing between a moving bearing sleeve and its adjacent bearing sleeve. The recesses 75,76 formed in the rings 71,72 may be filled with a suitable solid or granular lubricant material to enhance the anti-friction effect between the rings 71 and 72 and the sleeves 24a, 23a respectively.

As seen, the assembled bearing units with their anti-friction components and sealing rings maintain the lubricant grease within the roller bearings and prevent the rolling fluid entering the inner chamber of the bearing units. At the same time the reaction to the compression of the rings 82-85 is sufficient to maintain the rings 71,72 in contact with the edge faces of the adjacent sleeves 24a, 23a.

If there is a steering effect from the strip, i.e. the strip moves or "shunts" sideways, the sleeves 24 tend all to move towards one side. The ring 71 then acts as a thrust bearing, because it "bottoms" against outer sleeve 24a at points 90 and 91. A gap 70 remains and direct contact between sleeves 24 and 24a is avoided.

The seal unit has the features that it 1. will accept high rubbing speeds, 2. istolerantto hostile fluids, and 3. acts as a thrust bearing when required to do so by the steering effect of the strip.

Claims (11)

1. Astripshapemetercomprising: a mandrel; a series of bearing units arranged in axial sequence about the mandrel but capable of radial adjustment relative to the mandrel, each bearing unit having an outer sleeve supported by an inner sleeve through a bearing race and designed to be engaged and rotated by the strip; and, for each bearing unit, at least one load detector unit seated on the mandrel and lying between its bearing unit and the mandrel, the load detector units being substantially aligned axially adjacent the intended area of contact of the strip with the bearing units; characterised in that the radial width of the bearing units is substantially the same for all such units and the radial depth of the load detector units is substantially the same for all such units, and in that fluid-operated means are arranged to load each bearing unit against its load detection unit and are connected to a common supply duct for fluid under pressure, whereby all the bearing units are loaded equally on to their detection units and the exteriors of all the bearing units are equally spaced from the mandrel at the area of strip contact regardless of variations in the diameters of the bearing units.

2. A strip shapemeter according to claim 1, in which the fluid-operated means for each bearing unit comprises at least one piston and cylinder assembly arranged between the mandrel and the inner sleeve of the bearing unit at a position displaced from the load detector unit.

3. A strip shapemeter according to claim 2 in which the supply duct is formed in this mandrel and is connected through the mandrel with each of the piston and cylinder assemblies.

4. A strip shapemeter according to claim 1 or claim 2, in which, for each bearing unit, the piston and cylinder assembly constitutes a key between the mandrel and the inner sleeve to hold the inner sleeve against rotation.

5. A strip shapemeter according to any one of the preceding claims, in which each load detector unit comprises a load detector secured to a mounting block having a thickness giving the overall depth of the load detector unit a predetermined value and seated on the mandrel.

6. A strip shapemeter according to any one of the preceding claims, in which each load detector unit includes an electrical load transducer the leads of which pass through an axial conduit located between the mandrel and the bearing units.

7. A strip shapemeter according to claim 6, in which at one end at least of the mandrel there are duct means opening at one end to the conduit and at the other end to the exterior in the axial direction towards the other end of the mandrel, the duct means carrying the leads out of the shapemeter.

8. A strip shapemeter according to any one of the preceding claims, in which, between the sleeves of consecutive bearing units, there are sealing means comprising a substantially rigid bearing ring of anti-friction material housed largely in, but protruding from, an annular recess formed in the sleeve of one bearing unit and facing the sleeve of the other bearing unit, and resilient means between the bearing ring and the sleeve of said one bearing unit biasing the ring against the sleeve of the other bearing unit and forming a seal between the bearing ring and the sleeve of said one bearing unit.

9. A strip shapemeter according to claim 8, in which the resilient means comprise two abutting resilient rings housed in facing recesses in the bearing ring and in the face of the recess housing the bearing ring.

10. A strip shapemeter according to claim 8 or claim 9, in which the bearing ring has a recess facing the sleeve of the ther bearing unit for the reception of solid or particulate lubricant.

11. A strip shapemeter substantially as herein described with reference to the accompanying drawings.