IMPROVEMENTS IN BELT CONVEYOR TRAINING IDLERS

Abstract: If a conveyor belt creeps sideways, belt training idlers are used to return it to a central position. Conventionally the training idlers do this by pivoting about an axis normal to the conveyor belt surface (i.e. they "slew"). The slewing of the present training idlers however is also accompanied by a sideways tilting movement to increase the realigning influence of the idler. The combined movement of the idler is enabled by spherical bearing (10) which links frame (4), carrying idler roller (5), to base frame (9). This bearing acts as a modified universal joint, with one degree-of-freedom removed by support rollers (11) attached to a shaft through the spherical bearing along axis (12) in the direction of belt travel on each end of shaft (11). When respective servo roller (3) [alternatively pairs of servo rollers (13) may be used] is contacted by a misaligned belt edge it serves to slew the frame (4) to which it is attached about axis (6) passing through the bearing. At the same time a respective roller (7) on frame (4) is driven down an angularly adjustable inclined track (8) attached to base frame (9) so that the idler is tilted as well as slewed.

Description: CT/AU91/00488 - 1 - IMPR O VEMENT S IN BELT CONVEYOR TRAININ G IDLER S This invention relates to improvements in training idlers for belt conveyors. With conventional training idlers, t h e motion of the idler trainin g the belt is generally restricte d to a slewin g action about a central vertical axis normal to the width of the belt. The angle b etween the training roller an d t h e b elt generates a lateral re-aligning influence on the belt that has b ecome misaligned from its central p osition d ue to other influences. The idler slewin g frame is normally driven b y servo rollers on either side of the belt, which in turn are ac t iva t e d by the belt as it misaligns laterally. The re-ali g nin g influence that a training idler of this confi g uration can exert on the belt is limite d b y SUBSTITUTE SHEET the single degree-of-freedom of training movement available to the idler and the frictional force that can be developed between the belt and the training idler. The invention described below is designed to overcome this limitation by introducing an additional degree- of-freedom of training movement, which enables the idler to tilt sideways about an axis parallel to the conveyor, at the same time as it slews, thus considerably increasing the re-aligning influence exerted on the belt. This facilitates considerable cost savings, by enabling a single training idler to do the work of multiple training idlers of conventional design. One form of the invention is represented in t e accompanying drawing. Fig. i. As the belt 1 misaligns sideways relative to its direction of travel 2, it comes into contact with one of the two side mounted servo rollers 3. The said servo idlers are attached to the tilt frame 4, which in turn supports the belt support roller 5. The force exerted on the said servo idler causes the tilt frame / belt support roller assembly to rotate about an axis 6, normal to the width of the said conveyor belt, generally referred to as slewing motion . The said tilt frame also has guide rollers 7, mounted at each end, and these correspond to tracks 8, at either end of the base frame 9. The said tracks are inclined at an angle to the said direction of belt travel. The said tilt and base frames are connected by a plain spherical bearing 10, and shaft assembly which behaves as as a ball joint, permitting all three angular degrees-of-freedom. Support rollers at each end of the shaft 11, limit one of these angular degrees-of-freedom, and prevent the said tilt frame/belt support roller assembly from collapsing onto the said base frame. As the said assembly begins to slew, the said guide roller on the opposite side to the direction of belt misaligning movement comes into contact with the underside of the corresponding said track, and is driven down the said track. Only one of the two said guide rollers is active and in contact with its said track at any time. The movement of the said active guide roller lowers the near side of the said tilt frame / belt support roller assembly, and raises the far side, thus causing the said assembly and said conveyor belt to rotate about an axis 12, substantially parallel to the said direction of belt travel, generally referred to as a tilting motion. This generates two additional re-aligning influences ; (a) It creates variable tension across the said conveyor belt, with lower tension on the near side and higher tension on the far side, inducing a tendency for the said conveyor belt to return to its central position to equalise the tension across the said conveyor belt. (b) It enhances the re-aligning effect of the said slewing component of motion, by creating a downward path for the said conveyor belt. This invention is designed to work in either the top or bottom belt strands of the conveyor, and with the said conveyor belt in a variety of configurations. The flat belt support roller depicted in Fig. 1 can be replaced by two-roll, vee configuration idlers, or multiple roll trough configuration idlers. 085 The ratio between slew and tilt angles can be regulated by varying the angle of inclination of the said tracks. The track angle is adjustable by means of rotating the said tracks about a pivot point on the track support 090 plate 14. The said guide rollers and tracks may be arranged in a number of alternative configurations, for example ; (a) With the said tracks fixed to the said tilt frame and the said guide rollers fixed to the said base 095 frame. (b) With the said guide rollers running on the top side of the said tracks as opposed to the underside of the said tracks as depicted in Fig. 1. The single servo rollers depicted in Fig. 1 can be 100 replaced by multiple servo roller assemblies 13, with the assemblies pivoting on a shaft 16, about axes normal to the belt. In order to distribute the load evenly between individual rollers, the multiple servo rollers are 105 mounted on walking beams 15. This reduces the edge pressure on the said conveyor belt, and enables each training idler to do considerably more work without damaging the said conveyor belt. 110 The lateral distance between said servo rollers and edges of said conveyor belt, may be adjusted by means of an adjustment screw 17. This enables variation within a nominal belt width to oe accommodated, and also enables the sensitivity of 115 the training idler to be adjusted by varying the amount of lateral misalignment of the said conveyor belt required to activate the training idler.

Claims: The claims defining the invention are as follows :- 1. Conveyor belt training idler for correcting the lateral misalignment of moving conveyor belts, said training idler comprising a mechanism which senses the said lateral misalignment of the conveyor belt and rotates the said conveyor belt sideways about an axis substantially parallel to the direction of conveyor belt travel, in order to exert a realigning influence on the said conveyor belt, said rotation being referred to in subsequent claims as tilting. 2. Conveyor belt training idler as claimed in Claim 1, wherein the said mechanism includes : a base frame mounted independently of the said conveyor belt ; and a second frame, supporting a roller or rollers upon which the width of the said conveyor belt runs, and connected to, or mounted on the said base frame, whereby said second frame tilts relative to said base frame, said second frame being referred to in subsequent claims as the tilt frame. 3. Conveyor belt training idler as claimed in Claim 2, wherein the said mechanism also includes a means of rotating the said tilt frame relative to said base frame, about an axis substantially normal to the said width of conveyor belt, (referred to in subsequent claims as slewing) . 4. Conveyor belt training idler as claimed in Claim 3, wherein the said mechanism also includes : a means of mounting the said base frame so that it is stationary, relative to the said conveyor belt ; a means by which the said tilt frame pivots on the said base frame ; and a roller mounted adjacent to each edge of the said conveyor belt and attached to the said tilt frame, said rollers sensing lateral movement of the said conveyor belt, and inducing a slewing action in the said tilt frame, said rollers being referred to in subsequent claims as servo rollers. Conveyor belt training idler as claimed in Claim 4, wherein the said mechanism also includes : a track on each side of the said conveyor belt, attached to the said base frame, and inclined at an angle to the direction of conveyor belt travel ; a roller attached to each side of the said tilt frame and rolling on the said tracks, said rollers being referred to in subsequent claims as tilt rollers, and by interacting with the said tracks, converting a portion of the slewing input from the said servo rollers into tilting. Conveyor belt training idler as claimed in Claim 4, wherein the tracks described in Claim 5 are mounted on the tilt frame, and the said tilt rollers are mounted on the said base frame. 7. Conveyor belt training idler as claimed in either Claims 5 or 6 , and including a means of adjusting the said angle of incline of the said tracks such that the said portion of slewing input converted to tilting can be varied. 8. Conveyor belt training idler as claimed in any of Claims 5, 6 or 7 , wherein the dual tracks and rollers described are replaced with a single track and roller, 9. Conveyor belt training idler as claimed in any previous claim, wherein the pivot referred to in Claim 4 permits only the tilting and slewing angular degrees of freedom, of the said tilt frame relative to the said base frame. 10. Conveyor belt training idler as claimed in Claim 9, wherein the pivot includes ; a spherical plain or rolling-element bearing mounted to either the said tilt frame or base frame, and permitting all three said angular degrees of freedom ; a shaft through the said spherical bearing, connecting the said base frame to the said tilt frame ; and a roller on each side of the said spherical bearing, and mounted on the said shaft, said rollers allowing only the said tilting and slewing degrees of freedom by bearing against the opposite frame to which the said spherical bearing is mounted, said spherical bearing being mounted in either the said tilt or base frames. 11. Conveyor belt training idler as claimed in any previous claim, wherein the single servo rollers described in Claim 4 are replaced by multiple units of two or more individual rollers in order to distribute the load on the edge of the said conveyor belt. 12. Conveyor belt training idler as claimed in any previous claim, wherein the servo roller units described in either Claims 4 or 11 are mounted by a means which permits the distance between the said servo rollers and said conveyor belt to be adjusted, in order to accommodate variations within a nominal conveyor belt width, and to adjust the amount of said lateral misalignment of the said conveyor belt required to activate the training idler, 13. Conveyor belt training idler substantially as described herein with reference to the accompanying drawing.

Inventors: HUTH ALAN, SUNDSTROM PAUL, HUTH, ALAN, SUNDSTROM, PAUL
Applicants: TASMAN ENG PTY LTD, TASMAN ENGINEERS PTY LTD.
Application year: 1991
Main classification: B65G39
IPC codes: B65G39