Patent GB-562810-A (GB)
Title: Improvements in or relating to a device for indicating elastic deformation of the frame of a rolling mill stand
IPC: G01L5/00
Filed: 1942-06-13
Abstract: 562,810. Strain gauges. SPERRY PRODUCTS, INC., and STEVENS, A. H. (Sperry Products, Inc.). June 13, 1942, No. 8108. [Class 40 (i)] [Also in Group XIX] The strain-indicating system for rolling - mills of Specification 550,385 in which the effect of movements of the sensitive element is continuously counteracted except when material is passing through the mill is modified by causing the compensator to be rendered ineffective by a switch controlled by movement of the material or by the operation of the indicator of a preceding mill instead of by means responsive to the rate of change of strain. In addition, the gauge element is mounted in such a position that it is affected only by vertical tensile strain and not by bending and it, and the part of the frame on which it is mounted, are encased in heat-insulating material. Construction and mounting of gauge element. The member 55 forming part of the magnetic circuit of a differential transformer is carried by a torsion wire pivot and has a projection clamped to a wire 30 which is secured at one end to a bracket 31 on the frame 11 and coupled to a similar bracket 32 at the other end via a spring. The whole is enclosed in a casing 65 which, together with the frame member in the neighbourhood of the gauge is given a covering of heatinsulating material. Circuit arrangements. In the absence of material from the mill, any output from the gauge is combined with that from an interference-compensating circuit IE and that of a pair of potentiometers P1, P2 in the input circuit of an amplifier A, the output of which drives a compensator motor CM which adjusts P1 until the effective input to the amplifier is zero. When the material is about to reach the first of a series of mills provided with strain indicators, it operates a switch to energize a relay 78 which controls the application of a scale-breaking spray and energizes a relay 70. The latter changes over the amplifier connections of the indicator associated with such mill so that subsequent output currents energize a motor DM which drives P2 until the effective input is zero, and at the same time driving an indicator 66 calibrated in pressures. As soon as the indicator goes off normal, it energizes a relay 87 over contacts 92 which makes the circuit independent of relay 78 and operates the relay corresponding to 70 in the indicator system of the next mill. When the material leaves the mill, the indicator is driven substantially to zero and contacts 92 are restored to release 87, 70. The shunt across the righthand half of the operating winding of DM in this condition constantly tends to drive DM towards zero. Phase adjusting networks are provided for the interference eliminating circuit, the potentiometers and the gauge output. To prevent hunting, reverse retroaction is employed in the amplifier by means of a transformer T5. To re-set the dial, if it fails to return when current is switched on after a break, a switch S2 is moved to its middle position to release 87, 70 and DM is restored under the influence of the shunted right-hand half of its operating winding. When it is necessary to indicate the loading in the absence of material, the switch S2 is moved to the right to energize 120. Thereafter 70 is under the control of contacts operated whenever the screw-down motor is energized instead of contacts of relay 78. In these circumstances, the release of 70 by the opening of the contacts controlled by the screw-down motor is delayed by a circuit 170 and both halves of the operating winding of DM are then shunted to give dynamic braking.