CONVEYOR BELT ROLLER OR PULLEY WITH RENEWABLE CONTACT

SURFACE

FIELD OF THE INVENTION

This invention relates to a conveyor belt roller or pulley having a contact surface that is operatively contacted by a conveyor belt being supported or guided by what is typically an idler roller or driven by a drive pulley. More particularly, the invention relates to a conveyor belt roller or pulley wherein the contact surface is renewable.

In order to simplify the description of the present invention, the term roller as used hereinafter is intended to Include both freely rotatable idler rollers; as well as drive pulleys or drums and tail pulleys or drums; as well as any other guide or support rollers or pulleys that contact the surface of a belt conveyor in use,

BACKGROUND TO THE INVENTION

It is commonplace to provide conveyor belt rollers with a rubber layer on the outer surface thereof in order to protect the metal roller from wear and tear and to provide a contact surface for engagement by a conveyor belt. In the case of driving rollersis also important to provide traction to inhibit slipping of the belt on the driving roller and an outer rubber layer serves this purpose as well. Such rubber layers are generally bonded to the outer surface of the metal roller sometimes involving even the in situ vulcanisation of the rubber, whether it be hot or cold vulcanisation.

As a result of the bonding process, when the time comes to renew the the surface by replacing the rubber layer, considerable time and effort is involved in removing the worn layer preparatory to a fresh layer being applied to the

roller. Not only this, but the fresh layer generally takes some time for any bonding agent to cure or vulcanisation to take place and there is thus a considerable time factor involved in carrying out the replacement procedure. This often translates into downtime of a production facility and can become extremely expensive.

One attempt to overcome the disadvantages associated with this procedure, and of which applicant is aware, is the provision of prefabricated external metal shells or leaves that are adapted to be secured to the outer surface of the roller and wherein the metal shells or leaves have bonded to the operatively outer surface thereof, a rubber layer. These metal shells or leaves are typically welded to the outer surface of the roller and, accordingly, when they are to be replaced, the welds attaching the worn shells or leaves to the roller must be broken, the resultant broken welds must be ground smooth, and the new shells or leaves welded in position. A considerable amount of skilled labour is required in order to achieve this replacement procedure.

Irrespective of the above, a totally separate requirement of an outer rubber layer is that, under wet conditions, it should not cause the conveyor belt to plane over it, and thus slip, in consequence of water that becomes spread over the roller surface. Considerable effort is often expended in forming drainage grooves or the like in the surface of the rubber layer in order to drain water away from the contact areaand maintain proper contact between the conveyor belt and roller surface.

OBJECT OF THE INVENTION

It is an object of this invention provide a conveyor belt roller that has a renewable contact surface that overcomes, at least to some extent, the difficulties outlined above.

SUMMARY OF THE INVENTION

In accordance with one aspect of this invention there is provided a conveyor belt roller of generally cylindrical shape and having its own outer surface an a separate contact surface radially outwards thereof for operative engagement by a conveyor belt in association with which the roller is used, the roller being characterized in that the contact surface is a composite surface made up of outwardly directed surfaces of a multitude of replaceable contact elements held in their operative relationship relative to the surface of the roller by mechanical attachment means that physically engage the elements to maintain them in cooperating relationship with respect to the roller.

Further features of the invention provide for the replaceable contact elements to be moulded or extruded polymeric elements that may have a friction affording surface property or, alternatively, a low friction property according to the purpose for which the roller is to be employed; and for the roller itself to have a cylindrical structural wall defining said outer surface and in relation to which the contact elements are in contact or in close proximity such that in use, the contact elements are urged into contact with such outer surface in consequence of contact between a conveyor belt and the outwardly directed surfaces of the contact elements.

In one variation of the invention the contact elements assume the form of circular or polygonal cross-sectioned cylindrical elements arranged in a required pattern over the surface of the roller. In such an instance the elements may have a squat stem portion force fitted into an aperture in a retainer fixed to the roller such that the apertures are spaced radially from the outer surface of the roller and wherein the elements are retained in position by mechanical engagement of the periphery of the aperture with a stem portion of an element. As an alternative, a contact element may assume the form of a cap that is force fitted over a headed retainer element secured to the outer surface of the roller itself.

In a second variation of the invention, the contact elements assume the form of strips extending longitudinally along the length of the roller and held in association therewith by mechanical retainer means fixed, either permanently or releasably, to the roller itself.

In order that the invention may be more fully understood various embodiments thereof will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:-

Figure 1 is a schematic isometric view of one form of conveyor belt roller according to the invention;

Figure 2 is a front elevation of one specific arrangement of roller of the general nature illustrated in Figure 1 ;

Figure 3 is an exploded isometric view showing the detail of one of the retainer sections and associated contact elements;

Figure 4 is a cross-section of part of the periphery of a roller having retainer sections and contact elements of the type illustrated in Figure 3;

Figure 5 is an elevation similar to Figure 2 showing two variations of retain as, one on each side of Figure 2;

Figure 6 is an end view of a roller illustrating the general principle of an apertured retainer member spaced from the roller surface;

Figure 7 is a development of a roller surface showing one alternative pattern of contact elements;

Figure 8 is a development of a roller surface showing a further alternative pattern of contact elements;

Figure 9 is a cross-section through a retainer member showing an alternative configuration of contact element;

Figure 10 is a cross-section through a retainer member showing a further alternative configuration of contact element;

Figure 11 is a schematic isometric view illustrating an individual retainer member for attachment to a roller surface and its cooperating contact element;

Figure 12 illustrates, in schematic isometric view, a variation ^' in which ^" the container element is in the form of a cap to be retained on an individual cooperant retainer element fixed to a roller surface;

Figure 13 is a schematic isometric view illustrating the second variation of the invention indicated above in which the contact elements are in the form of elongate strips;

Figure 14 is an end view of one embodiment of the second variation of the invention illustrated in general terms in Figure 13; and,

Figure 15 is an end view of a second embodiment of the second variation of the invention illustrated in general terms in

Figure 13.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

Figure 1 illustrates the general arrangement of the first variation of the invention indicated above. In this instance, a conveyor belt roller (1) of generally cylindrical shape has formed on the outside surface thereof a contact surface (2) for operative engagement by a conveyor belt in association with which the roller is to be used. As provided by this invention, the contact surface is a composite surface made up of the outwardly directed surfaces of a multitude of replaceable contact elements (3) that stand proud of the adjacent surface of the roller or retainer means whereby the container elements are held in association with the roller.

Referring now more particularly to Figures 2 to 4, the contact elements (3) may be of squat right circular cylindrical shape that provides a stem (4) that operatively extends into a cooperating aperture (5) in the raised web (6) of an inverted channel shaped retainer section (7) extending parallel to the axis of

- the cylindrical roller.

A series of the retainer sections is secured to the outer surface of the roller itself so as to substantially cover the entire surface of the roller, as illustrated most clearly in Figure 2. These retainer sections can conveniently be secured to the metal surface of the roller by forming welds (8) on the inside of the flanges of the channel shaped retainer sections with access being obtained by way of the apertures themselves in order to achieve this.

Mechanical attachment of the contact elements in position in the apertures is achieved by virtue of a somewhat elastomeric or deformable nature of the contact elements that are conveniently made of a suitable rubber, polyurethane, or other polymeric plastics material having the required surface properties for a relevant application. The material from which the contact elements is made enables them to be moulded such that the stem is oversized to an extent that enables it to be force fitted into the aperture,

typically utilizing a hammer, and to be removed similarly by using force, typically by screwing into a contact element a screw threaded tool (9) having a pronounced sharp flight such that the free end of the tool engages the outer surface of the roller and thereafter carries the element up the flight and out of the aperture by force.

As indicated above, the contact element may have a friction affording surface in application to drive pulleys, or any other pulleys, and a low friction the property for pulleys that do not require traction to drive a conveyor belt.

In any event the arrangement is that the inner end of the stem contacts, and is supported by, the outer surface of the roller when a conveyor belt contacts the contact surface, in use. In the embodiment of the invention illustrated the contact elements have a head (10) at the outer end and this head is spaced outwards from the web (6) of the retainer sections when the stem contacts the outer surface of the roller itself.

It will be understood that, in use, a roller constructed as described above will operate effectively with the spaces provided between adjacent contact elements forming an effective drainage arrangement for water to thereby avoid any planing of the conveyor belt on the outer surface of the roller.

When it is required to renew some or all of the contact elements, the individual elements may be removed in the manner indicated above, or in any other way, and replaced by new contact elements. The arrangement is such that contact elements need only be replaced in positions of greater wear which can also save considerably on costs.

It will also be appreciated that the replacement procedure can be conducted on site without the roller even be removed from its operative installation. The consequence is a substantial saving in time, and, accordingly, downtime that may otherwise have been occasioned by a total removal of the roller and

processing by the prior art method described above. Still further, it is to be noted that the replacement of the contact elements can be carried out using a relatively low level of skill and, accordingly, less costly labour than would be necessary for the invention of a conventional repair procedure.

Numerous variations may be made to the embodiment of the invention described above.

Thus, the retainer section described above may be replaced by numerous other forms of retainers. For example, as illustrated in Figure 5, in place of the longitudinally extending channel shaped retainer sections, circumferentially extending strips (11) may be use for the purpose of providing apertures for receiving the container elements, such strips also being held in spaced radial relationship relative to the outer surface of the roller itself. Numerous mechanical arrangements can be contrived and numerous different mechanical fastening arrangements can be provided to hold such strips in their operative position.

Figure 5 also illustrates, at the left-hand side thereof, the use of circumferentially extending straps (12) for holding the aperture providing strips or plates in position.

Figure 6 illustrates the general arrangement in which a circumferentially extending strut or plate (13) is spaced radially outwards from the outer surface of a roller (14) with the elements passing through the plate by way of the apertures.

The pattern in which the elements are arranged over the surface of the roller can be varied widely. In the embodiment of the invention illustrated in Figures 1 to 5, the elements are arranged in longitudinally extending rows and circumferentially extending columns such that they form a cylindrical square grid pattern. However, the pattern could be varied widely.

For example, as illustrated in Figure 7, the elements (15) in each row could be staggered relative to those of adjacent rows so that the rows could be closer together. Alternatively, in order to avoid straight rows that are parallel to the axis of the roller, the contact elements (16) could be arranged to conform to a chevron type of pattern, as illustrated in Figure 8.

Also, the contact elements themselves may be of many different shapes, such as polygonal cross-sectioned cylindrical elements arranged in a required pattern over the surface of the roller.

In order to enhance the captivity of the elements relative to the roller, and in any event in the case of the use of certain types of materials, it may be advantageous to provide a head on the inside of the contact element. One example of such an arrangement is illustrated in Figure 9 in which a contact element (17) has an enlarged head (18) that can be forced past the aperture to provide a more positive lock of the element to the roller.

As an alternative, a dovetail shape of head (19) may be provided for cooperation with a complementarity shaped aperture (21) in a longitudinally extending bar (22).

Figure 11 illustrates an arrangement in which individual retainer elements (23) are provided to be welded to the outer surface of a roller and to receive cooperant individual contact elements (24).

Figure 12 illustrates a further variation in which the contact element assumes the form of a cap (25) that is force fitted over a headed retainer element (26) secured to the outer surface of the roller itself, for example by means of a screw (27). The periphery of the skirt of the cap can be provided with a steel reinforcing ring (28), optionally of spring steel, for retaining the cap on the retainer element.

Turning now to the second variation of the invention, and with reference to Figure 13, the contact elements (29) may assume the form of strips extending longitudinally along the length of the roller and held in association therewith by mechanical retainer means fixed, either permanently or releasably, to the roller itself.

In the instance of the arrangement of Figure 14, arcuate cross-sectioned strips (30) that are made to approximately conform to the outer surface of the roller (31) have grooves (32) in their edges that receive a common key (33) that it shares with the adjacent edge of the adjacent strip. The keys are secured to the roller using fasteners such as screws (34) or any form of clip.

In the εirraηgement that is illustrated in Figure 15, trough shaped retainers

(35) extend longitudinally on the outside of the roller surface and are preferably welded to it. The edges of the trough shaped retainers are raised so as to cooperate with grooves in the edges of the contact element strips

(36) that in this embodiment of the invention are arranged to be slid longitudinally into their operative positions. It is envisaged that such arrangement may be particularly suitablefor use in certain types of plastics materials such as contact elements made of ultra high molecular weight polyethylene, for example. Such a material has particularly the wearing properties although it unsuitable for driven rollers.

Numerous other arrangements are possible within the scope of the invention as will be quite apparent to those skilled in the art.