Field of the Invention The invention relates to a helix train unloader and more particularly, but not exclusively, to a continuous helix train unloader for unloading bulk mining product from a train of railcars.

Background of the Invention

It is known to use rotary railcar dumpers and train positioners (indexers) for unloading bulk materials from railcars. For example, an existing system of rotary railcar dumper includes a rotating unit in which each railcar of the train is parked in succession. While the railcar is parked inside the rotating unit, clamps are used to secure the railcar in place and the rotary dumper is rotated so as to empty the railcar. Once the railcar is emptied, the rotary dumper is rotated in a reverse direction to return the railcar to its upright condition.

Although this method of unloading a railcar is effective, the applicant has identified that such existing systems are limited in their offloading rate because they require that each car be stopped within the rotary dumper in turn.

In another system disclosed in United States Patent No. 2,763,382, there is disclosed a train unloader which uses flat bed cars running along a twisted train track to unload a train clamped onto the flat bed cars. This system is inefficient as it requires each of the railcars of the train to be clamped horizontally and vertically in position on the flat bed cars.

Examples of the present invention seek to provide an improved train unloader using a helix action which overcomes or at least alleviates one or more disadvantages associated with the previous train unloaders. Summary of the Invention

In accordance with the present invention, there is provided a helix train unloader including:

a dumping apparatus having an entrance arranged to receive a railcar in an upright condition from a leading track portion, and an exit arranged to deliver the railcar in an upright condition to a trailing track portion;

wherein the dumping apparatus includes at least one spiral guide rail running continuously from the entrance of the dumping apparatus to the exit of the dumping apparatus, the spiral guide rail being located to engage the railcar and to thereby cause rotation of the railcar about a longitudinal axis of the railcar as the railcar passes through the apparatus along the spiral guide rail, rotating the railcar from the upright condition at the entrance of the dumping apparatus to a tilted condition in which bulk contents of the railcar drop from the railcar under gravity, and then returning the railcar to the upright condition at the exit of the apparatus.

The train is in continuous longitudinal motion. Preferably, the dumping apparatus includes opposed spiral guide rails running continuously from the entrance of the dumping apparatus to the exit of the dumping apparatus, the opposed spiral guide rails being located at opposite parts of the railcar so as to engage the railcar between the guide rails and to thereby cause said rotation of the railcar about the longitudinal axis of the railcar as the railcar passes through the apparatus along the spiral guide rails.

Preferably, the rail car wheel bogie assemblies and rail car body engage in such a manner that they do not disengage when the rail car is suspended from the spiral guide rails. This would allow the leading track to end as soon as the car is suspended from the spiral rail, and the wheels to reengage with the trailing track at the end of the spiral guide rails. In a preferred form, the opposed spiral guide rails are located at opposite sides of the railcar. Preferably, the opposed guide rails are arranged to engage guide castors located at opposed portions of the railcar. More preferably, each of the spiral guide rails has a curved engagement surface, and each of the guide castors has a correspondingly curved engagement surface. Preferably, the dumping apparatus has a pair of guide rails for engaging each opposite part of the railcar. More preferably, the spiral guide rails within each pair of guide rails are parallel.

In one form, the railcar has a pair of guide castors mounted on each of the opposed sides of the railcar such that each pair of guide castors runs along one of the pairs of guide rails. Preferably, each pair of guide castors includes a forward guide castor and a rearward guide castor.

Preferably, the spiral guide rails have a primary portion of straight travel where the rail car wheels disengage from the rails, a secondary transition portion of gradually increasing rate of rotation and a tertiary portion of constant rate of rotation.

In a preferred form, the dumping apparatus includes a plurality of frame surrounds through which the railcar travels between the entrance and the exit, the opposed spiral guide rails being supported by the frame surrounds. More preferably, the frame surrounds are spaced to allow bulk material from the railcar to fall between the frame surrounds.

In one example, the helix train unloader is for unloading ore from the railcar. Preferably, the railcar is rotated through at least 150 degrees by the spiral guide rails. In another form, there is provided a helix train unloader including:

a dumping apparatus having an entrance arranged to receive a railcar in an upright condition from an entrance track portion, and an exit arranged to deliver the railcar in an upright condition to an exit track portion;

wherein the dumping apparatus includes guide means, the guide means being located at opposite parts of the railcar so as to engage the railcar between the guide means and to thereby cause rotation of the railcar about a longitudinal axis of the railcar as the railcar passes through the apparatus along the guide means, rotating the railcar from the upright condition at the entrance of the dumping apparatus to a tilted condition in which bulk contents of the railcar drop from the railcar under gravity, and then returning the railcar to the upright condition at the exit of the apparatus.

In one form, the exit track portion is the entrance track portion, and the railcar changes direction between entering and exiting the dumping apparatus. In another form, the railcar passes through the dumping apparatus without changing direction.

In one variation, the guide means includes rollers mounted to the dumping apparatus, and the rollers are arranged to cooperate with guiderails mounted to the railcar to cause said rotation of the railcar. In an alternative example, the guide means includes rollers/castors mounted to the railcar and spiral guiderails mounted to the dumping apparatus.

Brief Description of the Drawings

The invention is described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic perspective view of a scale model helix train unloader, in accordance with an example of the present invention; Figure 2 is a diagrammatic side view of the helix train unloader shown in Figure 1 ;

Figure 3 is a diagrammatic cross-sectional view of the helix train unloader shown in Figures 1 and 2;

Figure 4a is a diagrammatic end view of a railcar of a helix train unloader in accordance with an example of the present invention;

Figure 4b is a diagrammatic side view of a railcar shown in Figure 4a;

Figure 5 shows a circular support of a helix train unloader in accordance with another example;

Figure 6 shows another circular support of the helix train unloader of Figure 5;

Figure 7 shows a graph of the motion of the example helix train unloader of Figures 5 and 6;

Figure 8 shows a helix train unloader in accordance with another example in which the relative positions of the rollers/castors and guiderails/guidebars have been reversed; and

Figure 9 shows further detail of a helix train unloader similar to the example shown in Figure 8.

Detailed Description

With reference to Figures 1 to 4b of the drawings, there is shown a helix train unloader 10 built as a 1 :30 scale model of a proposed system for unloading bulk iron ore material from a train of railcars 18. Advantageously, the helix train unloader 10 uses a plurality of opposed spiral guide rails 12 to tilt the railcars as they pass through the helix train unloader 10 such that the train of railcars is able to move continuously through, without stopping as is necessary in existing systems. Furthermore, the helix train unloader 10 depicted in the drawings does not require the railcars to be mounted and clamped to flat bed cars as in the train unloader disclosed in US Patent No. 2,763,382.

More specifically, the helix train unloader 10 shown in Figures 1 to 4b includes a dumping apparatus 14 having an entrance 16 arranged to receive a railcar 18 in an upright condition from a leading track portion 20, and an exit (not shown) arranged to deliver the railcar 18 in an upright condition to a trailing track portion.

The dumping apparatus 14 includes opposed spiral guide rails 12 running continuously from the entrance 16 of the dumping apparatus 14 to the exit of the dumping apparatus 14. The opposed spiral guide rails 12 are located at opposite parts of the railcar 18 so as to engage the railcar 18 between the guide rails 12 and to thereby cause rotation of the railcar 18 about a longitudinal axis of the railcar 18 as the railcar 18 passes through the apparatus 14 along the spiral guide rails 12. Accordingly, the railcar 18 is rotated from the upright condition at the entrance 16 of the dumping apparatus 14 to a tilted condition in which bulk contents of the railcar drops from the railcar 18 under gravity. Once the railcar 18 is unloaded through being suspended in the tilted condition, the railcar 18 is then returned to the upright condition in which it exits the dumping apparatus 14.

As can be seen, the helix train unloader 10 includes a right-hand side of spiral guide rails 12a, and a left-hand side of spiral guide rails 12b, to engage with sides of the railcar 18 so as to tilt the railcar 18 from the upright condition to the tilted condition, and then to return the railcar 18 from the tilted condition to the upright condition.

The rail car wheel bogie assemblies 22 and rail car body 18 engage in such a manner that they do not disengage when the rail car is suspended from the spiral guide rails. This would allow the leading track 20 to end as soon as the car is suspended from the spiral rails 12, and the wheels to reengage with the trailing track at the end of the spiral guide rails. By engaging the opposite parts of the railcar 18, the opposed spiral guide rails 12 cause the necessary tilting of the railcar 18 as the railcar moves along the guide rails 12. Although in the examples shown the opposed spiral guide rails 12 are located at opposite sides of the railcar 18, it will be appreciated that in other examples the proposed spiral guide rails 12 may be located at different opposite parts of the railcar (for example, a top location of the railcar 18 and a bottom location of the railcar 18) sufficient to support the railcar 18 and effect rotation for dumping of the bulk contents. In the particular example shown in the drawings, the opposed guide rails 12 are arranged to engage guide castors 24 located at opposite sides of the railcar 18. Each of the spiral guide rails 12 may have a curved engagement surface 26 (see Figure 3), and each of the guide castors 24 may have a correspondingly curved engagement surface (see Figures 4a and 4b). The dumping apparatus 14 may have a pair of guide rails 12a, 12b for engaging each of the opposite sides of the railcar 18 to provide additional support to the railcar 18. The spiral guide rails 12 within each pair 12a, 12b of guide rails are parallel to accommodate the fixed distance between the guide castors 24 at either side of the railcar 18. With reference to the end view of the railcar 18 in Figure 4a and the side view of the railcar 18 in Figure 4b, the railcar 18 has a pair of guide castors 24 mounted on each of the opposed sides of the railcar 18 such that each pair of guide castors 24 runs along one of the pairs 12a, 12b of guide rails. Each pair of guide castors 24 includes a forward guide castor 24a and a rearward guide castor 24b. By having one guide castor 24a forward of the other guide castor 24b, the guide castors 24 also assist in providing stability of the railcar 18 about a lateral axis of the railcar 18.

With reference to Figure 2, the opposed spiral guide rails 12 have a primary transition portion 28 of gradually increasing rate of rotation and a secondary portion 30 of constant rate of rotation. Returning to Figure 1, the dumping apparatus 14 may include a plurality of frame surrounds 32 through which the railcar 18 travels between the entrance 16 and the exit, the opposed spiral guide rails 12 being supported by the frame surrounds 32. The frame surrounds may be spaced to allow bulk material from the railcar 18 to fall under gravity between the frame surrounds 32.

With reference to Figure 3, in the example illustrated, Plate A has an outside diameter of 270mm, an inside diameter of 210mm and is a full circle. Plate B has an outside diameter of 240mm and carries only the lower spiral. The Insert C has an outside diameter of 240mm, an inside diameter of 210mm and carries only the upper spiral. Holes marked with an asterisk are the only holes in the Plate Insert C.

Although the example described with reference to Figures 1 to 4b has opposed spiral guide rails 12 configured to rotate the railcar 18 to a minimum of 150 degrees between the upright condition and the tilted condition, it will be understood that in alternative examples the degree of rotation may differ. The 1 :30 scale model is a 'part model' only and constructed to show only the first 100 degrees (see Fig 2). In order to fully off-load the car 18, the car 18 must be rotated through 150 degrees in order to discharge its full load. Also, it will be understood that while in some examples of the invention the opposed spiral guide rails 12 are configured to tilt the railcar 18 in one direction then return the tilt car 18 in the opposite direction, in alternative examples the opposed spiral guiderails 12 may be configured to tilt the railcar 18 in one direction to unload the railcar 18 then to continue rotating the railcar 18 in the same direction so as to rotate the railcar 18 a full circle to return it to its upright condition.

Figures 5 to 7 show further details of the example helix train unloader shown in Figures 1 to 4b, and like features are denoted with like reference numerals. Figure 5 shows a frame surround 32 in a section of the helix train unloader in which there is no rotation of the railcar, as is evident from the guiderail 12 pairs being equidistant on both sides of the surround 32. This is in contrast to the frame surround 32 shown in Figure 6 in which the guiderail 12 pairs are not equidistant - rather, the guiderails 12 for the rear castors 24b has rotated more from the horizontal than have the guiderails 12 for the front castors 24a (116.64 degrees as compared to 102.4 degrees). This shows that the railcar is actually rotating in an anti-clockwise direction when passing through the frame surround of Figure 6, when travelling in a direction into the page.

With reference to Figure 7, there is shown a graph depicting motion of the railcar, wherein said primary transition portion 28 of gradually increasing rate of rotation of the railcar extends for the first 2 metres of the distance along the spiral of a 1 :30 scale model, followed by the secondary portion 30 of constant rate of rotation which extends for (at least) the next 1.5 metres. Rotational acceleration of the railcar is sinusoidal such that there is zero acceleration at the start and end of the primary transition portion 28.

Further details and design fundamentals of the model shown in Figures 5 to 7 are provided below in point form.

• The 1 :30 scale model of a spiral ore wagon unloader was built to demonstrate the principle of this method of unloading an ore train, but within the confines of an average size room. This caused a number of constraints besides the obvious limit on the physical size. The wagons on the model retain their bogies despite leaving the rails and being rotated, the centre of rotation being the centreline of the couplings between wagons.

• The model has four distinct sections:

o An 'assembly area' where the wagons are supported on their bogies on 'rails'

o A parallel 'transfer' section, 0.5m long, where the rails have terminated and the wagons are under control of the bars which form the spiral track. This part of the track is straight to allow the transfer to occur,

o An acceleration zone, where the rotational speed of the wagons increases according to a predetermined motion schedule.

o A zone where rotational velocity of the wagons is constant. In order that the model replicated the principles of a full size version, a realistic mathematical model of the motion of the wagons was used which with modification, could be extrapolated to a full size version. The overarching requirement was to keep dynamic forces to a minimum while still performing the rotation required in an acceptable path length. To achieve this, not only the peak angular acceleration needs consideration but also the need to limit the 'jerk' (the derivative of acceleration, i.e. the rate of change of acceleration.) to a finite quantity.

Wheels to support the wagon within the spiral were added to the body of the scale ore wagon, two at the upper front, and two at the lower rear. The amount these wheels protrude from the side of the wagon partially determines the magnitude of the helix. As the helix angle increases, the upper track of the spiral will impinge on the top rear corner of the wagon, only avoided by moving the support wheels outwards. A compromise on the scale wagons limited the helix to a rotation of 40° per metre, or approximately 14° per wagon.

The length of the track was limited to what would fit reasonably within an office, and with the above restriction on the maximum rate of rotation the following motion program was settled on, assuming a constant forward velocity. Because the rate of rotation is proportional to the forward velocity (which is unknown), all values are given as rate of rotation per metre of forward displacement. o Accelerate (angular acceleration) from zero to 40° per metre over approximately 2 metres and 40° rotation, using sinusoidal acceleration, o Rotate at a constant 40° per metre for 1.5 metres to give a total rotation of approximately 100°. Further rotation at this rate can occur and would simply require additional length,

o The total length of the model spiral represents an approximate 140m length on a full-size version. If a similar deceleration zone were to be used at the exit then an additional 7.5m of spiral would allow a full 360 rotation. The model spiral length required would be approximately 1 lm or 330m in full size.

It should be noted that the track could be continued with complete rotation of the wagon, or it is possible to halt rotation and then reverse it if required.

The spiral track is constructed of four round bar 'guiderails' which in pairs, form an upper and lower track for the front and rear support wheels respectively. These rails are held in place by circular shape "frame surround" plates which have been laser cut to accurately position the guiderails.

To allow passage of the wagon, the rotation of the upper and lower helix guiderail pairs must rotate identically, but offset horizontally by the distance between the support wheels on the wagon. To simplify the helix construction, the distance between the frame surrounds was made the same distance as the distance between the wheels, in this case 356mm. Therefore the rotation of the upper pair of helix guiderails on any particular plate is identical to the rotation of the lower pair of helix guiderails on the previous plate, since the front and back of each wagon must have rotated by the same amount (see Figures 4b and 6).

To ensure a 'smooth' acceleration up to a constant rate of rotation, sinusoidal acceleration was employed. This has the advantage of zero acceleration at the start and end of the acceleration zone and a smooth transition throughout. The 'jerk' (the differential of acceleration or the rate of change of acceleration) is finite throughout. The jerk can be eliminated altogether by a slightly more complex motion program, but this has the disadvantage of slightly higher peak acceleration if the same boundary conditions are met. In addition the subtle changes required to the shape of the spirals were considered beyond capabilities available in manufacture of the model so sinusoidal acceleration was a fair compromise. • The motion can be described graphically as shown in Figure 7. Values of acceleration and velocity have been multiplied by two to give comparable magnitudes on this common graph.

Sinusoidal acceleration uses the following equations of motion for the acceleration zone:

Variables are: a rotational acceleration (degrees/m ² )

v rotational velocity (degrees/m)

Θ rotation (degrees)

β 2x length of acceleration zone

h 2x total rotation in acceleration zone

s displacement along path of helix

Maximum velocity at end of acceleration zone is given by:

V _max =2h/

In this instance β=4ηα, and h=80°, giving a final velocity of 40°/m.

2ττΗ ^

So: Angular acceleration d ² 6/ds ² a -—^- siniZri—) Angular velocity d6/ds v = ^ (1- COS(2TT ))

s 1 s

Rotation angle θ Θ = h(--— sin(2Tr -)

In another variation, it may be preferable to reverse the location of the spiral guides and the rollers/castors. For example, to localise the maintenance requirements, it may be desirable to have spiral guides fitted to the cars, with rollers located in the unloader. This may assist in minimising roller numbers and would eliminate a "moving target" for roller/castor maintenance. Examples of systems of this type are shown in Figures 8 and 9 of the drawings. With reference to Figure 8, there is shown a railcar unloading system in accordance with an example in which the relative positions of the rollers/castors and guiderails/guidebars have been reversed when compared to the systems shown in Figures 1 to 6. In particular, the guide rails 12 previously mounted to the dumping apparatus 1 have been replaced by guide rails 34 (which may alternatively be termed "bars" or "tusks") mounted to the railcars 18. The guide rollers 24 previously mounted to the railcars 18 have been replaced by rollers 36 mounted in spiral lines which form part of the dumping apparatus 14. Accordingly, the system is similar in that it still uses rollers on guide rails to guide rotation of the railcars 18 about a longitudinal axis of the rotating coupler between cars, however the rollers are now arranged in spiral lines as part of the dumping apparatus 14 and the guide rails are now arranged as guide bar stubs mounted to each of the railcars 18. Rotation about the axis of the rotating coupler between cars is important to maintain the stresses of pulling the cars through the dumper in a straight line. With reference to Figure 9, the spiral lines of rollers 36 are arranged such that the cars 18 rotate 360 degrees through a right hand spiral. The cars will move through a transition zone to a constant rate of rotation as the cars 18 are emptied.

Key design issues to resolve include:

· Ensuring there is no interference between the rotating cars and fixed structure.

• Optimising the number of rollers while providing adequate support of the cars.

• Minimising the distance of the fixed supports from the car walls to preserve car integrity.

• Designing suitably shaped ore car supports (the guide bars 34) to allow transition from normal car orientation to the rotating phase.

Although the upper guide bars 34 are shown as being at the front of the cars 18 and the lower guide bars 34 are shown as being at the rear of the cars 18, in an alternative example the upper guide bars 34 may be at the rear of the cars 18 and the lower guide bars 34 may be at the front of the cars 18. The guide bars 34 may be fitted at any location along each railcar, not necessarily at the front and/or rear thereof. In one concept, the guide bars 34 each have a round cross-section, and the rollers 36 have matching round concave cross-sections such that the guide bars 34 are seated within the rounded cross-sections of the rollers 36. The rollers 36 may be configured to rotate about axes which are exactly (or substantially) horizontal such that the rollers 36 provide vertical support to the railcars 18 throughout the 360 degree rotation of the railcars 18.

In an alternative example, the guide bars 34 each have a square cross-section, and there are three sets of rollers rotating about different axes to support the guide bars in different directions - a first set of rollers which run along a normally upper surface of the guide bar, a second set of rollers which run along a normal lower surface of the guide bar, and a third set of rollers which run along a normally outer surface of the guide bar. This arrangement may be implemented on opposite sides of the railcars 18.

The rollers 36 may be 400mm in diameter, and successive rollers 36 may be spaced at 600mm intervals.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.