GB2102956A - Roll gap measuring apparatus - Google Patents

Abstract

Apparatus for a roll stand for determining the gap between the rolls, in which the spacing of the mountings, of the roll stand is determined. Transducers are arranged in lower or upper mountings and are set mechanically with respect to a measuring surface M to their zero position for the desired spacing. A housing 12, on one side, receives an adjustment nut 13 and has two projections. One projection 14 serves as a stop for an axially movable sleeve 16 and another projection 15 serves as a counter-face for a spring 17 bearing on a flange of the sleeve. The nut and sleeve have through-holes for a measurement transmitter support 23, which can be moved by a piston 24 under pressure. A chamber has supply and discharge lines 26, 27 for a medium for displacing the sleeve and piston. At its free end the transmitter support 23 comprises the measurement transmitter 28a with a measuring tip 28 movable against a spring. A clamping member 31 inserted between the transmitter support and the sleeve clamps the sleeve to the transmitter support. <IMAGE>

Description

SPECIFICATION Roll gap measuring apparatus The invention relates to a measuring apparatus for a roll stand for determining the control viable for adjusting the gap between the rolls, in which case the spacing of the mounting members of the roll stand, in particular the spacing of the mounting members of the backing rolls of a fourhigh roll stand is determined, in that built-in transducers are arranged in the lower or upper mounting members of the two housings of the roll stand, which transducers are adjusted mechanically with respect to a measuring surface to their zero position in adaptation to the respective desired spacing dimension of the backing roll mounting members.

When rolling strip material it is normal to undertake an adjustment of the strip thickness in order to achieve close strip thickness tolerances.

In addition to solving the dynamic requirement made of such an adjustment, a sufficiently quickacting adjusting system and a determination of the control variable which as far as possible is free from time lag are required. Of the known solutions for measuring the roll gap, firstly measurement by way of induction gauges with direct intervention at the rolls (German PS 1 931 654) seems to be advantageous. However, locating such measuring instruments on the rolls causes great difficulties.

The measuring instruments must be completely dismantled each time a roll is changed.

In order to obviate these drawbacks, a further measuring apparatus (German OS 2 439 580) measures from mounting member to mounting member, in which case the spacing of the backing roll mounting members of a four-high stand is used as the control variable for adjusting the roll gap position. However, in practical operation, this known device can be used only for a narrow measuring range, which can be extended up to a maximum of 2.5 times the overall measuring range of the displacement measuring instrument.

This results in a limited possibility of application, since the measuring displacement of the inductive measurement transmitter must be small in order to achieve the high resolution of the signal. If the known measuring device were designed for a large measuring displacement, then the result of this would be that a poor measuring signal is obtained if only a small variation of the spacing of the roll mounting members had to be ascertained.

In addition, it must also be regarded as particularly disadvantageous that the zero point of the measurement transmitter must be located by way of a special control arrangement, which in addition takes place by way of a complicated lifting device, in which the lifting piston is held in the floating position and hydraulic locking mechanisms are brought into action by pressurelimiting valves, non-return valves etc. The arrangement has considerable dimensions.

The object of the invention is to provide a measuring apparatus with automatic setting of the zero point, which comprises an inductive measurement transmitter with a very small measuring displacement of for example 1 mm and less, but where the overall measuring range of the spacing measuring system should cover up to 100 times the measuring range of the displacement measurement transmitter and where furthermore the measuring apparatus is arranged in the roll stand in a non-destructive manner, so that above all the rolling force produced cannot influence the measurement transmitter in the case of a sudden removal of load from the roll stand and the related rebound of the stand.

This object is achieved according to the invention in that the measuring apparatus consists of a housing which on the side remote from the measuring surface of the opposed mounting member receives an adjustment nut which can be screwed on, that the housing is provided with recesses forming projections, of which one projection serves as a stop face for an axially moving sleeve and the other projection serves as a counter-face for a spring bearing against a flange of the sleeve, that the adjusting nut and the sleeve comprise through holes for a displaceable measurement transmitter support, which is able to move with a piston able to be acted on by a pressure medium, in a chamber limited by the adjustment nut, in which case the chamber comprises supply and discharge lines for a pressure medium for displacing the sleeve and the piston, that at its free end the measurement transmitter support comprises the measurement transmitter with a measuring tip which is able to move against spring force and that a clamping member inserted between the measurement transmitter support and the sleeve clamps the sleeve to the measurement transmitter support.

This produces a compact unit whereof the housing of small dimensions contains all moving members and the retaining or clamping device for the measurement transmitter support. The measuring displacement of the measurement transmitter, which can be adjusted by way of the adjustment nut having a fine thread, preferably outside the roll stand, but in which case a readjustment in the roll stand is possible, is so small that high measuring sensitivity and signal resolution are ensured with a low noise level of the amplifier. The measuring displacement is thus synonymous with the mechanical displacement of the housing rotated against the adjustment nut and can be seen as the spacing of the adjustment nut with respect to the sleeve, if the sleeve is pressed against its stop face. Both the mechanical as well as the electrical measuring displacement are identical.The pre-set measuring displacement of for example 1 mm is no longer altered after this and is also maintained if the total measuring range for equalizing the working roll wear and for machining extremely thick strips amounts to 50 mm for example. The large measuring range is determined by the measurement transmitter support able to move by way of the piston, which support can be clamped in position after placing the measuring tip on the measuring surface.

Theoretically, according to the example, material having an initial thickness of 50 mm could be rolled up to 1 mm, without the measuring accuracy being influenced thereby. The measurement transmitter is set up in the prestressed condition of the roll stand, i.e. the material to be rolled is already located in the roll gap.

One embodiment of the invention provides that the clamping member is constructed as pneumatically actuated air bellows with highspeed ventilation. According to a further feature of the invention, it is provided that the measuring force of the measurement transmitter is within the range of 1 50 to 200 grams and the clamping force applied to the measurement transmitter support by way of the clamping member constitutes 5 to 7 times the measuring force.It is thus ensured that in addition to the already known protected arrangement of the measuring apparatus in the backing or if necessary working roll mounting members close to the roll gap, where neither corrosive coolants can attack nor stress is produced in the case of fracture of the strip due to mechanical effects, the measurement transmitter clamped pneumatically during the measuring operation by way of the measurement transmitter support is not destroyed in the case of an excessively high rolling force. The clamping force is measured so that on exceeding 5 to 7 times the measuring force, the measurement transmitter support is automatically shifted and thus with 1000 to 1 500 grams contact pressure, yields to external forces, which results in automatic opening of the hydraulic screw down cylinders.

One embodiment of the invention is illustrated in the drawings and described in detail hereafter: Figure 1 is a diagrammatic view of a housing of a four-high roll stand with the measuring apparatus according to the invention, Figure 2 shows details of a measuring apparatus according to the invention inserted in a mounting member, in section on line I-I of Figure 1.

Figure 1 shows diagrammatically a housing 1 of a four-high roll stand not shown in further detail. Both housings of the roll stand contain apertures 3. In the apertures 3, upper and lower backing rolls 5 are located in the mounting members 4, 4a and the working rolls 7 are located in the mounting members 6, 6a.

On each side of the roll housing, two measuring apparatus 8 can be incorporated in the backing roll mounting members 4, which apparatus 8 are connected to provide totalization, so that tilting movements of the mounting members within the roll housing can be measured. Furthermore, changes in spacing or distance are ascertained by the measuring apparatus 8, which changes occur under the influence of the change of forces within the roll system.

As shown in Figure 2, the measuring apparatus 8 is located in a bore 11 in the upper backing roll mounting member 4. The measuring apparatus 8 consists of the housing 12, which at the upper end remote from the measuring surface M comprises a screwthread for an adjustment nut 1 3 having a fine thread.The housing 12 is provided with recesses, which on account of the varying diameters form projections 14, 1 5. The upper projection 14 serves as a stop face A for a sleeve 1 6 able to move axially in the housing 12, whereas the lower projection 1 5 serves as a support face for a spring 17 bearing against a flange 1 6a of the sleeve 1 6. At the lower end of the housing 12, the sleeve 1 6 is screwed by way of bolts 18 to a closure member 21.The adjustment nut 13 as well as the sleeve 1 6 with the closure member 21 have through holes 22 for receiving the movable measurement transmitter support 23, in which case pressure medium can be supplied to a piston 24 for moving the measurement transmitter support 23 in a chamber 25 limited by the adjustment nut 13.

The pressure medium is supplied and discharged by way of the lines 26,27.

The measurement transmitter support 23 comprises the measuring tip 28, projecting from the housing 12 and able to be moved back against spring force by a certain displacement W.

As shown diagrammatically in figure 2, the measuring tip 28 is connected by way of a rod 29 to the iron core 30 of the inductive measurement transmitter designated generally by the reference numeral 28a.

The position of the iron core 30 can be varied relative to the coils 34. For the purpose of electrical connection, a cable 33 is located above the measuring apparatus 8 in the area of the bore 11 not occupied by the housing 12.

Provided below the chamber 25 and between the sleeve 1 6 and the measurement transmitter 23 is a clamping member 31, which is constructed as pneumatically actuated air bellows. The pneumatic clamping system for the measurement transmitter support 23 is free from wear and is released by way of high-speed ventilation means 32 in the range of several milli-seconds. The clamping operation takes place without involving moving parts and exerts a static pressure on the measurement transmitter support. The contact force is measured such that in view of the frictional relationship between the measurement transmitter support 23 and clamping member 31, the maximum retaining force does not exceed the value of 7 times the measuring force of the measurement transmitter 28a. All centering or stop faces as well as the housing are hardened and ground and dimensioned for long service lives, corresponding to the high switching frequency.

The measuring apparatus operates as follows: the measuring displacement of the measuring apparatus 8 is fixed outside the roll stand, in that the adjustment nut 1 3 having a fine thread is rotated against the housing 12. The mechanical displacement, which is identical to the electrical measuring displacement, results from the spacing of the screwed-on adjustment nut 1 3 from the sleeve 16, when the latter bears against the stop face A (figure 2). The rotation of the adjustment nut 13 can take place by means of the adjusting bar 35. After the installation of the measuring apparatus 8 in the support roll mounting member 4, the measurement transmitter support 23 is put under pressure by way of the piston 24. For this purpose the pressure medium is supplied by way of the line 26.At the same time as this, the sleeve 1 6 which is likewise under pressure and which is designed as a pneumatic one-way cylinder, is moved until it presses against the stop face A of the upper projection 14. The piston 24 of the measurement transmitter support 23 is supplied with pressure medium until it bears by its measuring tip 28 on the opposed measuring surface M for the purpose of measuring distance.

With an increasing supply of pressure medium, the measuring tip 28 which is under spring force is displaced by the distance W until it bears against the annular face 23a of the measurement transmitter support 23.

In this condition, the clamping member 31 is placed under pressure by the lines 32, 32a, so that the measurement transmitter support 23 is clamped and forms a unit with the sleeve 16.

After clamping, the chamber 25 or the chamber section 25a above the annular face of the sleeve 1 6 is relieved of pressure. As soon as the pressure escapes, a restoring movement of the measurement transmitter support 23 takes place automatically within several milliseconds, which is brought about by the spring 1 7. The sleeve 16 presses in a spring-loaded manner against the screwed-on adjustment nut 13, as shown in broken lines at 16' in figure 2.Electrical zeroing of the inductive measurement transmitter 28a then takes place automatically, because with the return movement of the sleeve 1 6 against the adjustment nut 13 under the pressure of a spring, the measuring tip 28 is again removed from the measurement transmitter support 23, against whose annular face 23a it was pressed during setting-up, so that the measurement transmitter 28a is drawn into the measuring position, in which the iron core 30 comes into a zero position, in which the currents of the coils 34 cancel each other out and zero is indicated at the output of the measuring device (not shown).The measuring tip 28, whereof the regulating displacement W should moreover always be greater than the preset measuring displacement of the measuring apparatus 8, is spring-loaded in contact with the measuring surface M of the opposite mounting member 4, whereby the measuring apparatus 8 is ready for use for measuring or keeping the distance constant. This measuring position, which is also characterised by the position of the measuring sleeve 1 6 designated in broken line by the reference numeral 16' is illustrated in figure 2, whereas an illustration of the measuring tip 28 moved back against the annular face 23a has been dispensed with.

The deviation signal determined during the measuring operation-caused by displacement variations, which result from strip differences and rolling variations-is supplied to an electronic arrangement for a roll screw down system and processed on the understanding that the roll screw down system keeps the measured distance constant. For returning the measurement transmitter support 23 to its initial position, after ventilation of the clamping member 31, the chamber 25 is supplied with pressure medium by way of the line 27 and the measurement transmitted support 23 is drawn back by way of the piston 24.

The automatic spring-loaded return of the measurement transmitter support 23 with the inductive measurement transmitter 28a against a stationary, wear-free surface ensures constant relocation of the zero range of the measurement transmitter with very high accuracy of within 1 4.

In order to achieve this accuracy, no complicated devices which are liable to breakdown are required. Since the measuring system has only a very low weight (the moving parts involved in the measurement weigh approximately 1 5 grams), the measuring system is designed for high accelerations.

Claims (1)

1. Claims

   1. Measuring apparatus for a roll stand for determining the control variable for adjusting the gap between the rolls, in which case the spacing of the mounting members of the roll stand, in particular the spacing of the mounting members for the backing rolls of a four-high roll stand is determined, in that built-in transducers are arranged in the lower or upper mounting members of the two housings of the roll stand, which transducers are set mechanically with respect to a measuring surface to their zero position in adaptation to the respective desired spacing dimension of the backing roll mounting members, wherein the measuring apparatus comprises a housing which, on the side remote from the measuring surface of the opposite mounting member receives an adjustment nut which can be screwed on, the housing is provided with recesses forming projections whereof one projection serves as a stop face for an axially movable sleeve and the other projection serves as a counter-face for a spring bearing on a flange of the sleeve, the adjustment nut and the sleeve comprises through-holes for a movable measurement transmitter support, which can be moved by a piston acted upon by pressure medium in a chamber defined by the adjustment nut, in which case the chamber comprises supply and discharge lines, for a pressure medium for displacing the sleeve and the piston, at its free end the measurement transmitter support comprises the measurement transmitter with a measuring tip able to be moved against spring force and a clamping member inserted between the measurement transmitter support and the sleeve clamps the sleeve to the measurement transmitter support.

   2. Measuring apparatus according to claim 1, wherein the clamping member is constructed as air bellows which can be actuated pneumatically with high-speed ventilation.

   3. Measuring apparatus according to claim 1 or 2, wherein the measuring force of the measurement transmitter is within the range of 1 50 to 200 grams and the clamping force applied by way of the clamping member to the measurement transmitter support amounts to 5 to 7 times the measuring force.

   4. Measuring apparatus substantially as herein described with reference to and as illustrated in the accompanying drawings.

   New Claims or Amendments to Claims filed on 1 October 1 982 Superseded Claims 1-4 New or Amended Claims:

   1. Measuring apparatus for use in a roll stand control system for controlling the roll gap, said apparatus comprising a housing for mounting, on one side of a space between opposed roll mounting members, opposite a measuring surface on the other side of said space, a bore in said housing, an end wall of said bore carried by a cap in screw-threaded engagement with the inner end of the housing so that the end wall is adjustable axially of the bore on rotation of the cap, a measuring probe extending slidably through the cap and the bore, a sensing tip mounted at the outer end of the probe body for axial movement relative thereto, first biasing means for biasing the sensing tip outwardly and away from an inner end position with respect to the probe body, a setting sleeve surrounding said probe and slidable in said bore between an inner end position defined by said end wall and an outer end position in which an inner end face of the sleeve is spaced from said end wall by a distance which is predetermined by the adjustment of the end wall, second biasing means for biasing the setting sleeve into said inner end position, a piston fixed to said probe body within said sleeve so as to form with said end wall a double-acting fluid pressure drive for moving the probe in either axial direction relative to the sleeve, said sleeve being adapted to move outwardly into said outer end position by fluid pressure acting in opposition to the second biasing means, clamping means for selectively clamping the setting sleeve to the probe body, a measuring transducer having two parts relative movement of which is adapted to produce an output signal in use, one of said parts being movable with the probe body and the other with the sensing tip, whereby, in use, operation of the fluid pressure drive to extend the measuring probe outwardly of the housing is accompanied by movement of the setting sleeve into its outer end position and when the sensing tip contacts said measuring surface outward movement of the probe continues until the sensing tip is fully retracted in its inner end position whereupon the clamping means is operated to clamp the setting sleeve to the probe body and the fluid pressure is relieved so that the sleeve is returned through said predetermined distance to its inner end position by the second biasing means and the probe body is withdrawn from the sensing tip so as to position said tip at a distance from its fully retracted position equal to said predetermined distance while remaining in contact with said measuring surface, such return movement of the probe body serving to set the measuring transducer to a datum position independently of the dimensions of said space between the opposed roll mounting members.