AU658778B2 - Sole plate for bearing load measurement - Google Patents

Description

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AUSTRALIA

Patents Act 1990 658778

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Sole Plate For Bearing Load Measurement rrat I r ~tfr r c rr ri it tt

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ii L The following statement is a full description of this invention, including the best method of performing it known to us: ,t C t t GH&CO REF: P14782-H:TJS:JM 411/14782-H 2 BACKGROUND OF THE INVENTION THIS invention relates to a sole plate for bearing load measurement which can be used, for example, to measure the load in a bearing which supports a sheave wheel.

There are various applications in which it is desirable to measure the load in a bearing. For example, in mine winders, the force in the rope of the mine winder installation can be measured by measuring the load applied to the bearings which support the sheave wheel of the mine winder. Such measurements may be useful, for example, in detecting slack rope conditionis.

a SUMMARY OF THE INVENTION According to the invention a sole plate for bearing load measurement comprises a body shaped to support a bearing above a substrate, the i body having a central portion defining an upper support surface for supporting the bearing, with end portions on either side of the central portion, the end portions being adapted to support the sole plate on the substrate so that a load normal to the support surface of the sole plate causes deflection of the central portion of the body relative to the end portions, each end portion having an I section with a web extending transversely to the upper surface of the body, the webs being adapted to support respective sensors for measuring the deflection of the central portion of the body and thus the load applied thereto.

The webs of the end portions preferably lie in a common plane and -3.

preferably lie in a first plane normal to a second plane defined by the upper support surface of the body.

The end portions preferably define feet which support the body above the substrate with a clearance between the central portion of the body and the 4substrate.

According to one embodiment the sole plate comprises at least one strain gauge supported on each web thereof.

Preferably a mine winder installation is provided in which a shaft of a sheave wheel is supported by respective bearings each mounted on a sole plate of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a pictorial view of a sole plate for bearing load measurement according to the invention; a Figures 2, 3 and 4 are top, side and end views, 20 respectively, of the sole plate of Figure 1; Figure 5 is a diagram illustrating the forces affecting the sole plate in use; and Figure 6 is a table showing the relationship between C the various forces on the sole plate.

DESCRIPTION OF AN EMBODIMENT Figure 1 illustrates a bearing 10 for a sheave wheel of a mine winder. The sheave wheel is supported on a shaft, with the shaft being supported S8T :4H i 0 S:14782H/703 4 by a pair of the bearings 10 at either end of the shaft. The bearing housing is bolted to a sole plate 12, which supports the bearing above a substrate such as a steel beam or a pedestal.

The sole plate 12 comprises a central portion 14 which is generally rectangular in section and which is solid except for shallow longitudinal slots 16 at opposite sides thereof. The slots 16 accommodate wiring, which would otherwise be exposed, to strain gauges mounted on the sole plate. The sole plate has end portions 18 and 20 on either side of the central portion 14. The end portions 18 and 20 have an I sc ftion, with central webs 22 and 24 extending between respective head portions 26 and 28 and foot portions 30 and 32. The webs 22 and 24 lie in a common plane, which is normal to a plane defined by the support surface 38. At the extreme end of each foot portion 30, 32 is a respective foot 34, 36. The feet support the sole plate above the substrate with a clearance above the central portion 14 of the sole plate and the substrate, allowing a degree of deflection of the central portion under load.

The upper surface 38 of the central portion of the sole plate defines a e flat load support surface, with holes 40 at its corners, to which the bearing assembly 10 is bolted by means of bolts 42. Upstanding shoulders 44 and 46 are formed on the upper surface of the sole plate at each end of the support surface 38, on the upper surfaces of the respective head portions 26 and 28. The shoulders help to locate the bearing 10 on the sole plate. Apertures 48 are formed in the foot portions of the sole plate, extending through the feet 34 and 36, to allow the sole plate to be bolted to the substrate.

Formed in the webs 22 and 24, on opposite sides of each web, are two i pairs of opposed cavities 50, for four shear strain gauges (these devices are conventional and are not shown). The load carried by the sheave wheel is transferred to the bearing 10 and thus to the sole plate 12, causing stress and resulting strain in the sole plate. This strain or deflection of the central portion of the sole plate in turn causes deformation of the webs and the shear strain gauges in the cavities The four shear strain gauges are connected in a Wheatstone bridge in such a way that the output of the bridge is a linear function of the sum of the shear strains detected by each of the four gauges.

Tests of a prototype sole plate/load cell assembly showed that the microstrain output per kilonewton load and the amount of hysteresis in the output were strongly dependent on the support condition under the feet 34 and 36. The mininum hysteresis and best linearity were obtained with 10 to 15mm of conveyor belt rubber under the feet. With a 120 ohm strain gauge bridge, an output of 3,30 0,05 microstrain/kN was obtained, while with a 350 ohm strain gauge bridge, a figure of 3,37 0,05 microstrain/kN was obtained. At typical working loads, this would provide approximately 550 microstrain output.

o a Since the strain gauges in the sole plate are arranged to measure shear, •and because the gauges are connected so as to measure the sum of the strains in each gauge, the total output of the device is independent of the position of application of the load to the sole plate. A test was o° carried out, applying the load at the centre and at the quarter points of o 0 the sole plate. As expected, the bridge c:itput was exactly the same. It was also found that side loads on the sole plate have no significant effect, and that torsion forces on the sole plate, resulting from unevenness on the substrate on which the sole plate is mounted, resulted in minimal variations of the output of the strain gauge bridge.

6 By adding the outputs of the sole plate load cells at each end of the sheave wheel together, the vertical rope load on the sheave wheel can be resolved, and the effects of components out of the plane of the sheave wheel can be removed. Tests showed that the prototype of the sole plate provided a satisfactorily linear output over the required load range.

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Claims (8)

1. A sole plate for bearing load measurement comprising a body shaped to support a bearing above a substrate, the body having a central portion defining an upper support surface for supporting the bearing, with end portions on either side of the central portion, the end portions being adapted to support the sole plate on the substrate so that a load iiormal to the support surface of the sole plate causes deflection of the central portion of the body relative to the end portions, each end portion having an I section with a web extending transversely to the upper surface of the body, the webs being adapted to support respective sensors for measuring the deflection of the central portion of the body and thus the load applied thereto. A sole plate according to claim 1 wherein the webs of the, end ia ia portions lie in a common plane.

3. A sole plate according to claim 2 therein the webs lie in a first plane normal to a second plane defined by the upper support surface of the body. eo a S4. A sole plate according to any one of claims 1 to 3 wherein the end portions define feet which support the body above the substrate, with a clearance between the central portion of the body and the substrate. A sole plate according to. any one of claims 1 to 4 wherein upstanding transversely extending shoulders are formed at opposite ends of the upper support surface to assist in locating the bearing on the sole plate. S:, 8

6. A sole plate according to any one of claims 1 to wherein at least one cavity is formed in each web for receiving a respective sensor.

7. A sole plate according to claim 6 wherein the cavities are formed in opposed pairs on either side of the respective webs.

8. A sole plate according to any one of claims 1 to 7 wherein the sensors are shear strain gauges arranged to measure deformation of the webs related to deflection of the central portion of the body.

9. A sole plate according to any one of claims 1 to 8 with at least one strain gauge supported on each web thereof. A mine winder installation wherein a shaft of a sheave wheel is supported by respective bearings each mounted on a sole plate according to any one of claims 1 to 9.

11. A sole plate for bearing load measurement, 4 ,t o substantially as herein described with reference to the 4 S 20 accompanying drawings.

12. A mine winder installation, substantially as herein described with reference to the accompanying drawings. o4 Dated this 30th day of November 1993 #4a4 o 9Cioer C ANGLO AMERICAN CORPORATION OF SOUTH AFRICA LIMITED 0.I" By their Patent Attorney oGRIFFITH HACK CO. ,0 GRIFFITH HACK CO. 411/14782-F i p. i ABSTRACT SOLE PLATE FOR BEARING LOAD MEASUREMENT The invention relates to a sole plate for bearing load measurement and has particular application for measuring the load in a bearing of a mine winder. The sole plate of the present invention comprises a sole plate for bearing load measurement comprising a body shaped to support a bearing above a substrate, the body having a central portion defining an upper support surface for supporting the bearing, with end portions on either side of the central portion, the end portions being adapted to support the sole plate on the substrate so that a load normal to the support surface of the sole plate causes deflection of the central portion of the body relative to the end portions, each end portion having an I section with a web extending transversely to the upper surface of the body, the webs being adapted to support respective sensors foi measuring the deflection of the central portion of the body and thus the load applied thereto. S tc z ¢o 9ts ttr a I ct I Di IJ 411/14782-F I