TECHNICAL FIELD

[0001] The present invention relates to idler rollers and, more particularly, to a roller head assembly for conveyor idler rollers used in belt conveyors for bulk materials handling.

BACKGROUND

[0002] Referring to figure 1, conveyor idler rollers 10 are an integral part of transport conveyor 12, because they support the conveyor belt 14 that travels over them. The conveyor belt 14 is used for carrying materials 16. Conveyor idler rollers 10 commonly comprise a cylindrical conveyor idler roll tube housing 18 that has an end cap 20 at each end that in turn holds an axle 22 that passes through them from one end of the housing 18 to the other end in a so called "through shaft" conveyor idler roller (see figure 2).

[0003] Each end of the axle 22 is held in place in a separate slot 24 situated on a conveyor idler frame 26. The end caps 20 house bearings (not shown) through which the axle 22 passes and they in turn rotate in the housing 18 around the axle. The axle 22 is stationary and each end is fixed into place in the slot 24 of the frame 26.

[0004] Conveyors are commonly used to transport a wide range of materials (such as minerals including coal, iron ore, phosphate or bauxite) through various stages of the transport chain, commonly between a pit and the loading of ships at port. They are also used for agricultural purposes including for the transport of grain to and from silos.

[0005] As the output of mining and farming operations has increased, so to have the size of the conveyors, the width, length and weight of the conveyor belts, and the speed at which the materials pass along the belts from one end of the conveyor to the other end before the materials are discharged.

[0006] Two key causes of conventional conveyor idler roller failure are:

• the end cap that holds the axle in place breaks away from the end of the housing; or

• the bearings held in place by the end cap (that hold the axle that passes through the centre of the idler roller) fail because of the loads being placed on them or debris works its way into the bearing through the sealing arrangement. [0007] Conveyer idler roller failure can result in unplanned stoppages and lost production. In addition, frequent failures can require stocking higher inventory levels to service the conveyer. Conveyer idler roller failure can also result in belts and other conveyer components.

[0008] Australian patent number 2010210289 ("the Dunn Patent") discloses a stub axle and bearing assembly for a conveyor idler roller system. This system includes a bearing assembly which has an annular load bearing member which is formed on the stub axle within the bearing assembly. The annular load bearing member is designed to support loads on the conveyor idler roller system. However, the annular load bearing member increases the complexity of the bearing assembly which increases the cost of manufacturing that bearing assembly to a point where the idler roller comprising the bearing assemblies cannot be sold for a competitive price.

[0009] The Dunn patent also discloses an annular load bearing member comprising ball bearings. The ball bearings were designed to take angular loads. The ball bearings spin in different directions depending on the angular forces on the load bearing member. However, whilst changing direction, the ball bearings are likely to skid and undergo excessive wear. In addition, the ball bearings in the Dunn Patent are not housed in a cage, so that the ball bearings will rub against each other. The excessive wear leads to rim drag and accordingly the ball bearings in the angular load bearing member are a redundant feature which has no current practical application.

[0010] Furthermore, the bearing assembly of the Dunn Patent includes an adaptor which is fixed on the external end of the stub axle. If any adaptors are not properly fixed to the mounting, then the adaptors are prone to come off the end of the stub axle during the installation of the idler roll into its slot in the idler roll frame. In addition, because of the shape of the mounting, the roller can be inserted into the frame upside down by the installer. This will cause the roller to be misaligned under the conveyor belt. This can cause a loss of total indicated run-out which thereby creates belt flap and a malfunction of the conveyor idler roller system.

[0011] For the aforementioned reasons, the conveyor idler roller of the Dunn Patent has not been commercially manufactured to date.

[0012] Australian patent number 2002252178 ("the Syntron Patent") discloses an idler roller for a transport conveyor. This idler roller has a pair of roller heads, each of which comprises an inner bearing cavity and an outer support surface which is telescopically received within a respective open end of said roller housing. However, it is possible for the inner bearing cavity to separate from the outer support surface during operation of the idler roller (as there is no mechanical retention). If the end cap separates from the housing, then the idler roller will fail and thereby interrupt the operation of the transport conveyor. In the same way, there is no mechanical retention of the bearing assembly to stop the axle and bearings from entering the housing and coming apart from the conveyor roller.

[0013] In addition, the Syntron patent discloses the uses of two circlips to retain the bearings on the axle. However, the bearing design requires much more accurate adjustment, which is not available with the use of the circlips. If the bearing assembly is not adjusted correctly, then the service life of the bearing assembly is drastically reduced, which will lead to premature failure.

[0014] The idler roller of the Syntron Patent has a pair of bearing assemblies. However, the more bearing assemblies that the idler roller has, the greater the rim drag that will be created by the idler rollers. Increasing rim drag increases the amount of energy that is required to the drive the conveyor. On a typical roller, increased rim drag could increase the energy consumption and costs considerably. In addition, some drive motors will not have the capacity to drive idler rollers with a certain rim drag factor.

[0015] It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

OBJECT OF THE INVENTION

[0016] It is an object of the present invention to provide an improved conveyor idler roller for a transport conveyer that addresses or at least ameliorates the aforementioned disadvantages or provides a useful choice.

SUMMARY OF THE INVENTION

[0017] According to a first aspect of the present invention, there is provided a conveyor idler roller for a transport conveyor, the conveyor idler roller comprising: a roller housing; at least one bearing; a stub axle which is fitted into the bearing; and a roller head for retaining the bearing and stub axle in the roller housing wherein the roller head has a shoulder on an end surface configured for retention of the stub axle within the roller housing.

[0018] Preferably, the roller housing is cylindrical.

[0019] Preferably, a first end of the stub axle and roller head are enclosed by a first seal cap. More preferably, the position of the stub axle is fixed with respect to the seal cap by at least one fastener. More preferably still, the at least one fastener is a central screw passes through the seal cap and which engages with a threaded portion in the stub axle to fasten the seal cap over the roller head and stub axle.

[0020] Preferably, an end of the stub axle is swaged to the inner race of the bearing to provide for retention of the stub axle within the bearing.

[0021] Preferably, the stub axle is rotatably supported by the at least one bearing at at least one bearing race.

[0022] Preferably, the stub axle and bearing are manufactured as a unitary component.

[0023] Preferably, the at least one bearing race is a/are induction hardened bearing race(s).

[0024] Preferably, the bearing and stub axle is retained in position with respect to the roller head by a circlip to prevent movement of the bearing out of the roller housing.

[0025] Preferably, the bearing is a unit bearing.

[0026] Preferably, a second end of the stub axle and the at least one bearing are enclosed by a second seal cap.

[0027] Preferably, a first axle assembly comprising the at least one bearing, the stub axle and the roller head is positioned at a first end of the roller housing and a second axle assembly substantially similar to the first assembly is positioned at a second end of the roller housing.

[0028] According to a second aspect of the present invention, there is provided a method of manufacture of the conveyor idler roller of any of the above claims, wherein the method comprises the steps of: fitting a stub axle into a bearing; fixing the bearing in position with respect to the stub axle with a circlip; positioning the bearing and stub axle assembly from step (b) within a roller head; enclosing a first end of the stub axle and the at least one bearing with a first seal cap; positioning the roller head assembly from step (c) inside a roller housing wherein the roller head has a shoulder on an end surface configured for retention of the stub axle within the roller housing; and enclosing a second end of the stub axle and the roller head with a second seal cap. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings by way of examples only as follows:

[0030] Figure 1 is a perspective view of a known belt conveyor used in bulk materials handling for use with the conveyor idler roller.

[0031] Figure 2 is a section view of the conveyor idler roller of the present invention for use with the belt conveyor of figure 1 with roller bearings.

[0032] Figure 3 is a section view of the conveyor idler roller of the present invention for use with the belt conveyor of figure 1 with ball bearings.

[0033] Figure 4 is a perspective sectional view of the roller head assembly of figure 3 for use with the belt conveyor of figure 1.

[0034] Figure 5a is a perspective sectional view of the roller head assembly of Figure 2.

[0035] Figure 5b is a perspective sectional view of the roller head assembly of Figure 2 with screw thread retention of the stub axle and end cap housing.

[0036] Figure 6a is a perspective sectional view of the roller head assembly of Figure 3.

[0037] Figure 6b is a perspective sectional view of the roller head assembly of Figure 3 with screw thread retention of the stub axle and end cap housing.

[0038] Figure 7 is a perspective sectional view of the roller head assembly at one end of the conveyor idler roller of figure 2.

[0039] Figure 8 is a perspective sectional view of the roller head assembly at one end of the conveyor idler roller of figure 3.

[0040] Figure 9 is a perspective exploded view of the Figure 4 roller head assembly. DETAILED DESCRIPTION

[0041] Figures 2 and 3 show the conveyer idler roller of the present invention generally indicated by arrow 100. A roller head assembly 102 is positioned at each end of a cylindrical roller housing 104. The roller housing can be made carbon steel, Vitre Steel or aluminium for corrosion resistance and light weight.

[0042] Referring to Figures 2 to 9, each roller head assembly 102 has an outer labyrinth seal in the form of a top cap 106 made from stainless steel circular plate 1 mm thick. An inner labyrinth seal made of PTFE strip 108 can also be made by nylon or injection moulded plastic (in order to provide some flexibility and rigidity which assists the installation of the inner labyrinth seal 108). The outer labyrinth seal 106 interfaces with the inner labyrinth seal 108 to impede the ingress of dirt into a bearing which preferably a unit bearing 110. The top cap 106 can be serial marked for asset control stock take purposes of the stub axle 120.

[0043] The sealed unit bearing 110 can be a double row angular control ball bearing (DAC) 110A as shown in Figures 3, 4, 6a, 6b, 8 and 9 or a double row roller taper bearing (DRT) 110B as shown in Figures 2, 5a, 5b and 7. The unit bearing 110 provides low drag and consequently long service life (greater than 115,000 hours with bearing capacity of 39.7 Kn (DYN), 36.5 Kn (STAT). The bearing races 112 are induction hardened for improved wear.

[0044] An optional sensor and transmitter (not shown) can be fitted between the outer labyrinth seal 106 and the inner labyrinth seal 108 to sense parameters of the roller head assembly 102 such as rotation speed and operating time and variations in heat and vibration. A network signal is received by a network controller and displayed on a display screen for real time monitoring of roller performance for use with predictive maintenance and to decrease the need for physical inspections.

[0045] The roller head assembly 102 has a stub axle assembly 114 as shown in Figure 9. The stub axle assembly 114 comprises a central adapter screw 116. The screw 116 has a broach 118 which interfaces with a slot 24 in the frame 26 of the conveyor idler roller 10 (as shown in figure 1). In this way, the screw 116 and outer top cap 106 are stationary when the roller head assembly 102 and roller housing 104 are spinning. The broach 118 can be varied in height, width and depth to accommodate the size of the slot 24 in the conveyor frame 26 in which the roller head assembly 102 (as part of the conveyor idler roller 10) is to be installed. The screw 116 is threaded into a holder 120 to comprise the stub axle assembly 114. The stub axle assembly 114 has a bearing seat 122 to support the bearing 110 (see figures 4 and 9). In some embodiments of the invention, the screw 116 and the holder 120 are combined into one integral unit.

[0046] A roller head 124 houses the stub axle assemblyl 14 and unit bearing 110. An external end of the roller head 124 has a hole 126 in the centre best seen in Figure 9. The hole 126 is of a smaller diameter than the internal diameter of the roller head 124 which creates a shoulder 127 (as shown in Figure 4). The shoulder 127 retains the unit bearing 110, combined with the sub axle 120 in the outer end of the roller head 124. The unit bearing 110 is retained in the roller head 124, by an internal circlip 130. The stub axle 120 at its internal end is swaged 120A to the unit bearing 110 to hold it in place, in the inner hub 128 (seen in Figures 2, 3, 6a, 6b, 7 and 8). Alternatively, the stub axle 120 may be held in place via a lock ring 129 (seen in Figures 5b and 6b) which screws into screw thread 120B on the stub axle 120.

[0047] A seal cap 200 is used to stop the passage of air into and out of the roller head assembly 102. The seal cap 200 also retains lubricant within the roller head assembly 102. The roller head 124 has a retaining taper 132 and an abutment edge 134 (best seen in Figure 4). A corresponding edge 136 of the roller housing 104 is pushed into the retaining taper 132 using a swaging tool to form a second swage to retain the roller head 124 within the roller housing 104.

[0048] The roller head 124 may have strengthening webs (not shown) between the inner hub 128 and an outer hub 138. Whether the roller head 124 has webs will depend on the specifications required by the metallurgist at the casting foundry. The roller head 124 can be made of iron, steel, aluminium, polyurethane or other materials. Larger embodiments of the roller head 124 are preferably made of aluminium, in which case webs between the inner 128 and outer hub 138 are required for the metal cooling process.

[0049] A person skilled in the art will appreciate that the arrangement of the outer labyrinth seal 106 and inner labyrinth seal 108 can be varied without departing from the scope of the invention. Different arrangements may include a lip around the circumference of the roller head 124 with an optional countersunk inner labyrinth seal 108 to increase the thickness of the roller head 124; an enlarged inner labyrinth seal 108 and/or a fixed outer labyrinth seal 106 which may be increased and the outer seal 108 countersunk into the enlarged inner seal 106 in an effort to increase the effectiveness of sealing the roller head 124 to prevent ingress of dirt and moisture into the roller head assembly 102. Alternatively the outer seal may be fixed to the circumference of the roller with an internal sealing arrangement 106 being affixed to the stub axle so that it rotates internally under the outer seal 108. Figure 4 shows an alternative embodiment whereby a supporting clip 106 A engages at least two wells 120A, in the stub axle 120, to provide more secure contact between the outer seal top cap 106, inner seal 108 and the roller head 124 and therefore more efficient sealing. During assembly of the roller head assembly 102, the wells 120A can be filled with an adhesive or silicon. The inner seal 108 comprises an o-ring made from Teflon, PTFE, nylon or metal plate. The roller head 124 can be made from rubber to form an additional inner seal. Oil may be applied during assembly between the top cap 106, o-ring 108 and roller head 124 to aid in sealing efficiency. Together the top cap 106, o-ring 108 and roller head 124 form a mechanical seal to prevent ingress of dirt into the bearings 110A.

[0050] In use, the conveyer idler roller 100 is manufactured by fitting the stub axle 120 into the bearing 110; fixing the unit bearing 110 in position with respect to the stub axle 120 with a circlip 130; positioning the bearing 110 and stub axle assembly 120 from step (b) within a roller head 124; enclosing a first end of the stub axle 120 and the unit bearing 110 with a first seal cap 200 to form a roller head assembly 102; positioning the roller head assembly 102 from step (c) inside a roller housing 106 wherein the roller head 124 has a shoulder 127 on an end surface configured for retention of the stub axle 120 within the roller head 124 ; and enclosing a second end of the stub axle 120 and the roller head 124 with a second seal cap 106.

[0051] Over 1500 units of the conveyer idler roller 100 of the present invention have been supplied to commercial mines. Only 3 failures have occurred to date which provides a failure rate of less than 0.002 %. Two of these were due to ingress of impurities into the unit bearing 110 and one was due to defective swaging of the roller head 124.

[0052] Thus preferred embodiments have a number of advantages over the prior art including:

• Improved reliability and a resulting decreased need for maintenance with the bearings having a life span of at least 1115,000 hours, low drag and low tolerance (total indicator reading (TPI) of less than 0.5 mm, and with the conveyer idler roller 60 % lighter than conventional through shaft rollers. The conveyer idler roller of the present invention exceeds series 45 and super heavy duty CEMA (conveyer equipment manufacturers association) standards.

• Improved ease of use by facilitating retrofitting of the conveyer idler roller of the present invention with adapters.

[0053] In the present specification and claims (if any), the word 'comprising' and its derivatives including 'comprises' and 'comprise' include each of the stated integers but does not exclude the inclusion of one or more further integers.

[0054] Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases 'in one embodiment' or 'in an embodiment' in various places throughout this specification are not necessarily all referring to the same embodiment.

Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

[0055] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.