WO2006081610A1

WO2006081610A1 - Wear sensor

Info

Publication number: WO2006081610A1
Application number: PCT/AU2006/000121
Authority: WO
Inventors: Brian Davies
Original assignee: Brian Investments Pty Ltd
Priority date: 2005-02-01
Filing date: 2006-02-01
Publication date: 2006-08-10

Abstract

A wear sensor (40) comprises a probe (56) positioned in a hole (44) extending through a body subject to wear (42) such that the probe physically is affected as the body wears away, and a sensing means (54) for detecting and/or measuring the effect on the probe of the wear to the body.

Description

WEAR SENSOR

FIELD OF INVENTION

The present invention relates to a sensor for detecting wear on a hardened wear plate .

BACKGROUND

Plates of hardened material are often used to minimize the effect of wear on structural elements of a piece of equipment . The material of the wear plate is selected for resistance to wear . Examples of equipment which use wear plates include hoppers , bins and chutes used in rock handling equipment and ore processing plants . This sort of equipment can be exposed to wear in the form of sliding and/or gouging abrasion . The wear plates act as a sacrificial element so that plates are worn rather than the structural element of the equipment . The plates are readily exchanged once worn, thus extending the life of the working equipment .

Difficulties arise in gauging the extent of wear of these wear plates because , for example, the plates are often in difficult to access positions , and the wear to the plates is often uneven . It is consequently difficult to determine the exact timing of a wear plate change out because it is desirable to use the wear plate to the maximum extent of its life but not to the extent of failure . Figure .1 schematically shows that wearing of some plates is significantly greater than wear of other plates . Those plates subj ected to more wear need to be changed more frequently than those that are subj ected to less wear . Rough calculations based on average wear rates can be used to determine approximate change out times of wear plates without actually removing the plate to assess its level of wear . However averages do not account for variables such as changing hardness of the material being handled, product flow rates etc .

There is therefore a need for a wear sensor for use with systems subj ect to wear .

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a wear sensing fastener comprising : a fastener element having a head subj ected to wear; the head having a hole therein having a set of physical characteristics prior to wear such that one or more of the physical characteristics are changed by wear of the head; whereby, in use , a change in the one or more physical characteristics of the hole indicate wear to the fastener .

In one embodiment the fastener element further comprises a shank . Typically the hole extends through the length of the shank .

In one embodiment the hole is blind prior to wear, but becomes open by wear of the head . In this embodiment wear past the point of opening the hole is detected by any one of the following : light passing through the hole, fluid flowing through the hole , or by probing for the hole opening .

In another embodiment the hole is open prior to wear and of a length that becomes shorter upon wear of the head. In this embodiment the fastener further comprises a sensing means for detecting and/or measuring the dimensions of the hole . This may be conducted by positioning the sensing means in the hole . The sensing means may be one of the following : a light sensor, a fluid flow sensor, a movement sensor, a sonic dimension measuring sensor, or an electrical characteristic measuring sensor .

According to a second aspect of the present invention there is provided a wear sensing fastener comprising : a fastener subj ectable to wear; a bind hole longitudinally extending through the fastener such that the blind end of the hole is opened when the fastener is sufficiently worn.

According to a third aspect of the present invention there is provided a wear sensor comprising : a body subj ected to wear; a hole extending through the body; a wear resistant member positioned in the hole such that material causing wear to the body will move the wear resistant member through the hole as the body wears away; and a sensing means for detecting and/or measuring the movement of the wear resistant member .

According to a fourth aspect of the present invention there is provided a wear sensor comprising : a body subjected to wear; a hole extending through the body; an ablative member positioned in the hole such that material causing wear to the body will also ablate the ablative member as the body wears away; and a sensing means for detecting and/or measuring the ablation of the ablative member .

According to a fifth aspect of the present invention there is provided a wear sensor comprising : a probe positioned in a hole extending through a body subj ected to wear such that the probe will be physically affected as the body wears away; and a sensing means for detecting and/or measuring the affect on the probe of the wear to the body.

DESCRIPTION OF DIAGRAMS

In order to provide a better understanding preferred embodiments of the present invention will now be described in greater detail , by way of example only, with reference to the accompanying drawings , in which : Figure 1 is a schematic representation of a wear plate system attached to a piece of equipment showing varying wear over the surface of the wear plate system;

Figure 2 is a cross sectional elevation of a first embodiment of the present invention prior to wear; Figure 2A is an enlarged schematic cross sectional elevation of a variant to the embodiment in Figure 2 ;

Figure 3 is a schematic cross sectional side elevation of the embodiment of Figure 2 having been subjected to wear; Figure 4 is a partial cross sectional side elevation of a second embodiment of the present invention prior to wear;

Figure 5 is a schematic cross sectional side elevation of the embodiment of Figure 4 having been subj ected to wear;

Figure 6 is a schematic part cross sectional side elevation of a third embodiment of the present invention;

Figure 7 is a schematic part cross sectional elevation of an end cap sensor for attaching to the embodiment of Figure 6 ;

Figure 8 is a side elevation of a measuring rod for use with the embodiment of Figure 6 ;

Figure 9 is a cross sectional side elevation of the embodiment of Figure 6 , the rod of Figure 8 and the end cap sensor of Figure 7 assembled for use according to the present invention; Figure 10 is a schematic cross sectional side elevation of an alternative embodiment to that shown in Figure 9 ;

Figure 11 is a schematic side elevation of an assembled fourth embodiment of the present invention;

Figure 12 is an exploded side elevation of the embodiment of Figure 11 ; and

Figure 13 is a cross sectional exploded view of the embodiment of Figure 11.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 shows a wear plate system 10 comprising a plurality of wear plates 12 fastened to a backing support structure of a piece of equipment by use of fasteners 14. The wear plates 12 collectively form a surface 11 which is subj ected to wear . Two types of wear indicator 16 and 18 in accordance with the present invention are showed installed on the wear plate system 10. The wear sensor 16 is combined with a fastener 14 whereas the wear sensor 18 is not .

Figures 2 and 3 show one embodiment of a wear sensor 20 in accordance with an embodiment of the present invention. The sensor 20 includes a body 22 that extends through a hole 13 in the wear plate 12. The body 22 has a surface 24 which is co-planar with surface 26 of the wear plate 12. Surfaces 24 and 26 are subj ect to wear and contribute to surface 11. The body 22 includes a hole 30 extending from an opposite end of the body 22 towards the surface

24. In this embodiment the hole 30 is blind and ends at wall 32.

Figure 3 shows the embodiment of figure 2 once wear has occurred. Part of the wear plate 12 has been worn away as indicated by 34 , part of the body 22 has been worn away as indicated by 36. The hole 32 is no longer blind with the wall 32 having been removed and opening 38 created. Wall 32 is positioned so that the blind hole 30 becomes open when a certain amount of wear has occurred to the wear plate 12.

With the opening of the hole light can pass through. From the back of the wear plate a pin hole light will appear as the light passes through the hole 30 of the worn wear indicator 20. Alternatively where the wear system 20 is carrying a wet material , liquid will begin to bleed through the hole 30 once it is opened thereby providing an alternative indication that the level of wear has reached a certain level . A further alternative is to insert a probe into the hole 30 to sense whether the hole is blind or has been opened .

Figure 2A schematically shows an alternative hole 30 ' in the body 22. The hole 30 ' has a reducing diameter extending further into the body 22. In this embodiment the diameter of the hole is stepped however it may be conical in shape or of some other appropriate shape . A probe can be inserted into the hole 30 ' and it can be determined at which diameter of the hole 30 ' the opening 38 is situated thereby enabling the extent of wear to be determined.

In the embodiments above the body is a separate integer

(sensor 18 in Figure 1) to the wear plate . However it is envisaged that the body may be integrally formed with the wear plate . Furthermore the body 22 could take various forms . The body 22 may take the form of a fastener

(sensor 16 in Figure 1) , as for example described in the next embodiment .

Referring to Figures 4 and 5 there is shown another embodiment of a wear indicator 40 which has been incorporated into a fastener for holding the wear plate 12 to a structural element 15. The wear indicator 40 includes a fastener (in the form of a bolt) having a head 42 and a shank 50. The shank 50 is threaded for receiving a retaining nut 52. The head 42 sits in a frusto conical hole 41 in the plate 12. The shank 50 passes through a hole 43 in the structural element 15. The head 42 and nut 52 cooperatively fasten the wear plate 12 to the structural element 15. This type of fastener is described in Australian provisional patent applications 2004907136 and 2004907031. The hole 41 has a half opening angle of about 5 - 20° and the head is of a complementary shape . It will be appreciated that other fasteners could be used, including traditional bolts . The top surface 48 of the head 46 is co-planar with the outer surface 26 of the wear plate 12 as in the previous embodiment . The bolt is adapted to the present invention by providing a hole 44 therein. Hole 44 extends through the shank 50 and head 46 almost to the surface 48. The wear sensor 40 further includes a sensing means 54. The sensing means 54 includes a sensor probe 56 in the form of a rod inserted within the hole 44. The rod 56 is fastened to the end of the shank 52 using a threaded retainer 58. The rod 56 extends through the length of the hole 44 so that as the wear plate 12 and head 42 of the fastener are worn away as indicated in Figure 5 part of the rod 56 as indicated by the shaded end 62 is also worn away. The extent of ablation of the rod can be measured thereby determining the extent of wear to the wear plate 12. The rod 56 provides an output through a cable 60 to an appropriate device for measuring the extent of wear to the rod 56.

Referring to Figures 6 - 9 , a further alternative embodiment of a wear sensor 70 in accordance with the present invention is shown. The wear sensor 70 includes a fastener 42 , sensing device 54 and a probe 56. Fastener 42 is similar to that described in Figures 4 and 5. The sensing device 54 includes a retaining nut portion 58 , a barrel portion 55 and a cable 60. Inside the barrel portion 55 is a series of wire windings 74 formed of electrically resistive material . The windings 74 are wound around a hole 75 in the barrel portion 55 and nut portion 58. The probe 56 is formed of a wear resistant material such as tungsten carbide . The probe is also shorter than the combined length of the hole 44 and the hole 75. Initially the probe 56 is positioned substantially within the hole 44 as depicted in Figure 9. An 0-ring 72 contacts the probe 54 and retains it in this position. However as the wear plate 12 and head 46 of the fastener are worn away, rather than the probe 56 being worn away as in the embodiment described in figures 4 and 5 it is pushed through the combined hole 44 and 75. In particular as the probe 56 moves through the barrel portion 55 of the sensing device this movement is detected. The movement detection is preferably provided by the number of windings of resistive material being short circuited increasing with movement of the probe due to the end of the probe making contact with an increasing number of windings as it is moved into the hole 75. The resistance of the windings that are not short circuited can be measured and thus the degree of movement of the probe can be measured. This in turn is indicative of the amount of wear that has occurred to the wear plate and head of the fastener . It will be appreciated that other embodiments of detecting the movement of the probe 56 can be implemented.

One alternative to the sensing device 54 is shown in

Figure 10. In this embodiment a linear motion sensor 76 is employed . Such a linear motion sensor is sold by Mitutoyo under series 542. The interior of the hole 75 may be provided with a grease which exits a bleed hole 78 as the probe 76 is moved by wear to the head 46 of the fastener 42. The linear motion sensor 76 provides a signal to a reading device (not shown) via electrical cable 60.

Referring to Figures 11 to 13 yet another embodiment of the wear sensor 80 is shown. In this embodiment the sensor includes a fastener 42 for fastening a wear plate 12 to a support structure 15 , a probe 86 and an end cap 82. The fastener 42 is secured to the wear plate and supporting structure by a washer 84 and retaining nut 52. A hole 44 is again provided within the fastener extending through the head and shaft of the fastener. In this embodiment the hole 44 is open . The hole 44 may be lined with a brass cylinder . The hole 44 again receives the probe 86. The probe 86 in this embodiment is comprised of a copper core 90 having windings 92 of non conductive lacquer coated nicron wire . An outer coating 88 of insulation is then provided over the windings of nicron wire 92. As the end probe is worn away contact between the nicron wire and copper core is at least intermittently provided . During these points of contact the resistance of the remaining length of nicron wire can be measured. The end cap 82 operates as an electrical connector . An internally threaded sleeve 98 can be screwed onto an externally threaded end piece 94 of the probe 86. The end piece 94 is in electrical contact with the adj acent end of the nicron wire 92. A central pin socket hole 96 contacts the copper core 90. A pin 100 of the end cap 82 proj ects into a socket hole 96 of the probe 86 when the end cap 82 is screwed in place . Thus the pin 100 is in electrical contact with the copper core 90. By measuring the resistance of the remaining nicron wire 92 the extent of wear to the probe can be determined, which in turn indicates the level of wear to the fastener 42 and therefore the wear plate 12.

An electronic circuit can be employed to measure the resistance of the nicron wire 92. The circuit can be adj acent to or remote from the probe 86. An embodiment of the circuit can include a transmitter which periodically transmits the measured resistance or a signal based thereon to a receiver which collates the readings from one or more such sensors to track over time the wear to the fastener 42.

An array of wear sensors according to the present invention can be deployed on the wear plate system 10. It then becomes possible to map out the extent of wear of the wear plates 12 without the need to remove them for inspection or the need to rely on rule of thumb methods . Thus plates that need changing can be changed at the most appropriate time .

It will be appreciated that the wear sensor need not take the form of a fastener and may be in the form of a body insertable into the wear plate as schematically illustrated in Figures 2 and 3 or the hole may be formed in the wear plate without the need for a independent body inserted within the wear plate .

Modifications and variations may be made to the present invention without departing from the basic inventive concept . Such modifications are intended to fall within the scope of the present invention, the nature of which is to be determined from the foregoing description.

Claims

THE CLAIMS OF THE INVENTION ARE AS FOLLOWS :

1. A wear sensor comprising : a probe positioned in a hole extending through a body subj ect to wear such that the probe physically is affected as the body wears away; and a sensing means for detecting and/or measuring the affect on the probe of the wear to the body .

2. A wear sensor according to claim 1 , further comprising an insert to the body, wherein the hole extends through the insert positioned in the body.

3. A wear sensor according to claim 2 , wherein the insert is a fastener .

4. A wear sensor according to claim 1 , wherein the body is a fastener .

5. A wear sensor according to either claim 3 or claim 4 , wherein the fastener has a head subj ected to wear .

6. A wear sensor according to claim 5 , wherein the fastener element further comprises a shank extends from the head.

7. A wear sensor according to claim 6 , wherein the hole extends through the length of the shank .

8. A wear sensor according to claims 1 to 7 , wherein the hole is blind prior to wear, but becomes open by wear of the body.

9. A wear sensor according to claim 8 , wherein wear past the point of opening the hole is detected by any one of the following : light passing through the hole, fluid flowing through the hole, or by probing for the hole opening .

10. A wear sensor according to claims 1 to 7 , wherein the hole is open prior to wear and of a length that becomes shorter upon wear of the body.

11. A wear sensor according to claim 10 , wherein the sensing means detects and/or measures the dimensions of the hole .

12. A wear sensor according to claim 11 , wherein the sensing means is one of the following : a light sensor, a fluid flow sensor, a movement sensor, a sonic dimension measuring sensor, or an electrical characteristic measuring sensor .

13. A wear sensor according to claims 1 to 8 or 10 or 11 , wherein the probe is worn away as the body wears away.

14. A wear sensor according to claim 13 , wherein the sensor means measures wear to the probe .

15. A wear sensor according to claims 1 to 8 or 10 or 11 , wherein the probe is moved as the body wears away.

16. A wear sensor according to claim 15 , wherein the sensor means measures movement of the probe .

17. A wear sensing fastener comprising : a fastener element having a head subj ected to wear; the head having a hole therein having a set of physical characteristics prior to wear such that one or more of the physical characteristics are changed by wear of the head; whereby, in use , a change in the one or more physical characteristics of the hole indicate wear to the fastener .

18. A wear sensor comprising : a wear resistant member for positioning in a hole extending through a body subj ected to wear such that material causing wear to the body will move the wear resistant member through the hole as the body wears away; and a sensing means for detecting and/or measuring the movement of the wear resistant member .

19. A wear sensor comprising : an ablative member positioned in a hole extending through a body subj ect to wear such that material causing wear to the body will also ablate the ablative member as the body wears away; and a sensing means for detecting and/or measuring the ablation of the ablative_ member .

20. A wear sensor according to either claim 18 or claim

19 , further comprising an insert to the body, wherein the hole extends through the insert positioned in the body.

21. A wear sensor according to claim 20 , wherein the insert is a fastener .

22. A wear sensor according to either claim 18 or claim 19 , wherein the body is a fastener .

23. A wear sensor according to either claim 21 or claim

22. wherein the fastener has a head subj ected to wear .

24. A wear sensor according to claim 23 , wherein the fastener element further comprises a shank extends from the head.

25. A wear sensor according to claim 24 , wherein the hole extends through the length of the shank.

26. A wear sensor according to claims 18 to 25 , wherein the hole is blind prior to wear, but becomes open by wear of the body.