GB2222397A - Loading bulk material into containers - Google Patents

Abstract

To load bulk material into a shipping container 12, an elongate conveyor 26 is used which extends right inside the container. As the container fills up and blocks the discharge openings of the conveyor, the energy needed to drive the conveyor increases. This energy is monitored and when it rises in this way, a signal is produced, and relative movement takes place between the conveyor and the container so that the discharge openings come to lie in a part of the container which has not yet been filled. This process is repeated until the container is completely filled. Two screw conveyors are employed, each within a hollow boom. <IMAGE>

Description

Loading Bulk Material This invention relates to the loading of bulk or granular material into an enclosed space such as a shipping container.

Shipping containers are conventionally used to transport piece goods as opposed to loose or bulk goods, but the efficiency of usage can be enhanced if it is possible to alternatively load containers with bulk goods.

According to the invention there is provided a method of loading bulk material into a shipping container, wherein an elongate conveyor with a feed opening and a discharge opening is positioned so that it extends into the container with the feed opening outside the conveyor and the discharge opening adjacent the furthest wall of the container, the conveyor then being operated to discharge material into the conveyor, wherein the energy needed to drive the conveyor is monitored such that when the energy needed rises above a predetermined level, the conveyor and/or the container is moved a predetermined distance so that the discharge opening is positioned a corresponding distance from the furthest wall of the container, and the process is repeated until the container is full.

In one embodiment, the monitoring of the drive energy for the conveyor results in the production of an audible signal which provides an indication to the driver of a tractor unit, connected to a trailer on which the conveyor is mounted, to advance the container in a direction moving away from the conveyor.

In an alternative and preferred embodiment, the monitoring of the drive energy for the conveyor results in the production of a signal which initiates retraction of the conveyor from the container by the predetermined distance.

The conveyor preferably continues to run whilst movement through the predetermined distance takes place.

The invention also provides loading apparatus for loading bulk material into a shipping container, the apparatus comprising two elongate screw conveyor booms each with a feed opening and a discharge opening, the feed openings being adjacent one another and the discharge openings being adjacent one another, a drive for driving the conveyor screws in rotation, means for sensing the energy needed to drive the screws and means for emitting a signal when the energy needed to drive the screws rises above a predetermined level.

When that part of the conveyor adjacent the discharge openings of the conveyors is full, then more energy will be needed to continue to drive the screws. Some time later the production of a signal related to the pushing effect of the screws will signify that that part of the container is full. The container can then be moved a certain distance forward, or the conveyor screws can be retracted, so that the pressure on the discharge ends of the conveyors is relieved.

The booms are preferably parallel, and their feed openings may communicate with separate feed hoppers or with a common hopper so that both screw conveyors can be fed from a single source of bulk material.

The or each hopper may be arranged so that it remains stationary during loading operation, with the conveyor screws being axially moved beneath the hopper. In order for the walls of the conveyor to remain closed throughout the axial movement of the conveyors relative to the hopper(s), the upper surface of the conveyor housings may be provided with flexible, overlapping closure flaps which can be parted by the bottom end of the hopper but will close the housings in those parts of the conveyors temporarily spaced from the hopper(s).

The two conveyors may be mounted on a base structure with the base structure being mounted on a platform for linear movement along the platform. The platform may be a wheeled trailer or the flat bed of a truck, and the length of the linear movement can be such that in one position the booms lie substantially within the overall length of the platform, and in the opposite end position they extend beyond the end of the platform by a distance substantially equal to the lengthwise dimension of a container to be loaded.

The platform can include rails and the base structure wheels which run on the rails.

The feed openings for the screw conveyors can have mouths of adjustable areas to control the rate at which conveying takes place.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of loading apparatus in accordance with the invention, in use in loading a conveyor; Figure 2 is a more detailed side view of the apparatus of Figure 1; Figure 3 is an end view of the apparatus, on a larger scale; Figure 4 is a plan view of the apparatus; Figures 5 and 6 are respectively cross sectional views on the lines A-A and B-B from Figure 2; Figure 7 is a side view showing the apparatus in its transportation position; Figure 8 is an electrical circuit diagram; Figure 9 is a detail view showing the hopper and the conveyor booms in vertical section; Figure 10 is a side elevation of the components of Figure 9; Figure 11 is a plan view of the components of Figure 9; and Figures 12 and 13 are detailed views respectively of the vertically and horizontally mounted rollers.

Figure 1 shows loading apparatus generally designated 10 in use loading a container 12. The container is mounted on a conventional trailer 14, and the trailer is towed by a tractor unit of which only the rear wheels are shown at 16. The container has a far end wall 18, a floor 20, a near end wall 22 and a roof 24. The near end wall 22 does not extend up to the roof and leaves a gap through which two screw conveyor booms 26 which form part of the apparatus 10 can project into the container. In order to seal the container, a flexible liner (not shown) can be placed inside the container, with the mouth of the liner at the top of the near end wall 22 so that the booms 26 extend inside the liner.

The loading apparatus comprises the booms 26, a feed hopper 28 and a drive motor 30 all mounted on a base structure 32, and the base structure 32 itself is mounted on rails 34 on a flat bed trailer 36. The flat bed trailer 36 can be towed in a conventional manner by a tractor unit which is not shown in Figure 1 but is shown in Figure 7 at 48.

In order to correctly align the booms 26 with the opening in the near end wall 22 of the container, the base structure 32 incorporates extensible legs. These legs are operated by crank handles 38 and 40 or may be operated hydraulically. The handle 38 controls the height at the rear of the structure and the handle 40 controls adjustable legs 42 and 44 on opposite sides of the front of the structure. These handles are connected to gearing arrangements so that turning of the handles causes the appropriate legs of the structure to extend or retract. The whole apparatus can be folded down for storage and transport by retracting the front legs 42, 44 and placing a support 46 on the trailer bed 36 to support the booms, as illustrated in Figure 7. The entire apparatus can then be transported from place to place simply by hitching the trailer to a conventional tractor unit 48.

Figure 4 shows a top view of the booms illustrating the conveyor screws and the drive arrangement. The booms extend parallel to one another and comprise cylindrical tubes inside each of which a conventional conveyor screw 50 is mounted so that it can rotate within the tube. Bulk material such as granular malt or other granular material is charged into the hopper 28 and then is directed by the sloping floor 52 of the hopper into the tubes which form two conveyor booms. Because the screws are rotating, the granular material is transported along the length of the boom to respective discharge openings 54 at the remote ends of the booms.

In order to control the rate of conveying, it would be possible to control the drive motor 30 to make the conveyors rotate at a desired speed. Alternately however if a constant drive speed is maintained, then the rate of conveying can be altered by adjusting the size of a window through which grain passes from the hopper 28 into the booms 26. This is shown on the right hand conveyor in Figure 3. The window area is shown here by a solid line 56, and an adjustable shutter 58 is mounted above the window. The shutter can be secured in any desired position, for example by means of one or more bolts passing through longitudinal slits and secured by butterfly nuts.

Both screws 50 are driven by a common, electrically operated motor 60 through drive belts 62 and 64. When the conveyor starts to operate, the granular material will fall freely from the discharge openings 54, and there will be no resistance to this discharging. However as the volume of discharged grain builds up, it will at a certain stage surround the discharge openings, and when this happens the conveyors will have to work harder to force grain out of the discharge openings.

This will result in a higher load being experienced by the motor 60, and this change in load is detected by monitoring the current level being drawn by the motor.

Figure 8 shows a circuit used to detect filling of the container. A power source 80 is connected to the motor 60 through a main switch 82 and a contact breaker 84. Indicator lamps 86 and 88 for "TRIP" and "RUN" conditions are both connected in to the power feed line. A current sensing relay 90 monitors the current drawn by the motor 60 through transformer windings 92 and operates when a predetermined current level is reached to produce a signal. This signal initiates relative movement between the container and the conveyor.

A signal is also sent to the contact breaker 84 via a time delay circuit 96. It is intended that the container and/or conveyor will move immediately the warning device 94 operates so that the ends of the feed screws are cleared from the conveyed grain, and the current level drops again. The time delay circuit will prevent shut down of the motor for a preset time period (eg. up to 60 seconds) to allow the movement to take place. However at the end of the time period, a signal will be sent to the contact breaker 84 and the motor will be shut down if the excess current level persists.

A spot light 98 controlled by a switch 100 is also powered from the source 80, and the entire circuit is enclosed in a weather-proof enclosure on the apparatus.

In use, the hopper 28 is positioned below a grain supply point which will normally be in a fixed position. It is necessary for the hopper therefore to remain in a fixed position below the supply point. In order to achieve the necessary relative movement between the discharge openings of the conveyor and the container, either the container can be moved gradually away from the conveyors, or the conveyors can be moved gradually out of the container. In the former case, the signal produced by the relay 90 causes an audible and/or visual signal to be given to the driver of the tractor 16 so that he can drive his vehicle on a predetermined distance which may be a metre or two. In the latter case, the signal causes a drive to operate to drive the conveyor booms back in a direction outward of the container for a metre or two.

Figures 9 to 12 illustrate the arrangement of the booms 26 and hopper 28 which allows the hopper to remain stationary below a grain supply point throughout an operating cycle while the booms move axially below.

The booms each have a pair of rails 120 running along their top faces forming a track 103 between them, and a series of longitudinal slots 102 which are open between the rails as can be seen in Figure 4. Flexible sealing flaps or strips 104, 106 are fixed at each side of each row of slots and overlap in the middle as shown on the left-hand boom of Figure 9 and in Figure 13. Over most of the length of the boom, these strips close the slots 102.

The hopper 28 has rectangular discharge slots 108 which can enter the track 103 between the rails 120 to discharge material through the slots 102 into the conveyors. When a discharge slot 108 enters the track, the sealing strips 104, 106 are guided around the sides of the discharge slot as can be seen in Figures 9 (right-hand boom) and 12. In order to guide the strips 104, 106, a pair of vertically mounted idler rollers 110, 112 and a single horizontally mounted idler roller 114 are mounted at either end of the hopper discharge slot.

The bottom ends of the discharge slots are incorporated into frames 116 which have wheels 118 running on the rails 120 on the conveyor booms.

The two conveyor booms 26 are braced to one another by cross braces 70. A guide abutment 72 at the remote end of each boom ensures that the boom is correctly positioned inside the container without damaging the container.

A pair of roof sensing rollers 74 are also mounted at the remote ends of the booms. As the container is filled, it will become heavier and will settle on the suspension of the trailer on which it is located. As a result, the roof of the container will become closer to the ground, but the boom height will remain the same. The wheels 74 are provided with sensors which sense the fact that the container roof is dropping onto the conveyor booms, and they send a signal which causes the front legs 42,44 to retract to prevent damage to the booms.

In order to move the apparatus backwards and forwards on the rails 34, a winch 78 is mounted on the base structure, with the other end of the winch cable being connected to a fixed point near the rear of the trailer 36. A similar arrangement can retract the conveyor booms beneath the hopper 28.

In use, the base structure is first moved to the rear of the trailer 36 by operating the winch 38. The trailer 36 is then positioned so that the hopper 28 is beneath an overhead grain supply point.

The container 12 which is to be filled is prepared by opening wide the hinged rear doors, lining the container with a polythene liner and mounting a part-height rear wall 22 at the back. The container on its trailer 14 is then reversed up to the apparatus on the trailer 36. If necessary the height of the booms 26 is adjusted using the crank handles 38, 40 so that the container can be moved to the position shown in Figure 1. Grain is then fed into the hopper 28 and the screw conveyors are operated to discharge the grain into the container. The grain will be fed continuously until the pile of grain accumulated on the floor of the container extends up to the roof and starts to bury the discharge openings 54.

When the discharge openings become buried, the increase in current drawn by the conveyors is sensed. This produces a signal which causes the booms 26 to be driven backwards out of the container, beneath the hopper 28 by the desired distance. The hopper is able to continue feeding into the booms as a result of the flexible connection between the booms and the hopper which is shown in Figure 9.

The distance which the booms move each time the signal is produced may be for example 300 mm, so that the discharge openings become located in an as yet unfilled space of the container and conveying continues. Each time the volume of the container around the discharge openings 54 is filled, another signal is produced and the conveyors are retracted another set distance.

The final part of the container to be filled is that adjacent the end wall 22 and once this part is full, then the polythene liner is closed and the container is separated from the loading apparatus.

Finally, it is just necessary to close the full-height container rear doors (these are not shown in Figure 1) with the temporary end wall 22 still in position inside the container.

The apparatus can be used to load any size conveyor. When the length of the booms is approximately equal to the length of the container, then loading can start at one end wall of the container and can continue until the container is completely full. If on the other hand the container is longer than the booms, loading can still be carried out starting from a point somewhere in the middle of the container wher the booms can reach to, and continuing to one end. In this case the container will not be completely filled but the degree of filling may be sufficient to load the container to its maximum allowable weight.

The loading apparatus thus described allows a container to be entirely filled with granular material in a very simple and effective manner.

Claims (17)

Claims:

1. A method of loading bulk material into a shipping container, wherein an elongate conveyor with a feed opening and a discharge opening is positioned so that it extends into the container with the feed opening outside the conveyor and the discharge opening adjacent the furthest wall of the container, the conveyor then being operated to discharge material into the conveyor, wherein the energy needed to drive the conveyor is monitored such that when the energy needed rises above a predetermined level, the conveyor and/or the container is moved a predetermined distance so that the discharge opening is positioned a corresponding distance from the furthest wall of the container, and the process is repeated until the container is full.

2. A method as claimed in Claim 1, wherein the monitoring of the drive energy for the conveyor results in the production of an audible signal which provides an indication to the driver of the tractor unit to advance.

3. A method as claimed in Claim 1, wherein, the monitoring of the drive energy for the conveyor results in the conveyor being retracted from the container by the predetermined distance.

4. A method as claimed in any preceding claim, wherein the conveyor continues to operate whilst the tractor moves through the predetermined distance.

5. A method as claimed in any preceding claim wherein the current drawn by the motor is monitored.

6. Loading apparatus for loading bulk material into a shipping container, the apparatus comprising two elongate screw conveyor booms each with a feed opening and a discharge opening, the feed openings being adjacent one another and the discharge openings being adjacent one another, a drive for driving the conveyor screws in rotation, means for sensing the energy needed to drive the screws and means for emitting a signal when the energy needed to drive the screws rises above a predetermined level.

7. Apparatus as claimed in Claim 6, wherein the means for sensing the energy to drive the screws comprises a current sensing relay connected to the signal emitting means.

8. Apparatus as claimed in Claim 7, wherein the current sensing relay is connected to the drive via a time delay.

9. Apparatus as claimed in any one of Claims 5 to 8, wherein the booms are parallel and their feed openings communicate with a common hopper.

10. Apparatus as claimed in Claim 9, wherein the hopper is arranged so that it remains stationary during loading operation, with the conveyor screws being axially movable beneath the hopper.

11. Apparatus as claimed in Claim 10, wherein the upper surfaces of the conveyor booms have longitudinal slots provided with overlapping flexible closure flaps, and the hopper is provided with means for parting the flaps locally.

12. Apparatus as claimed in any one of Claims 6 to 11, wherein the two conveyors are mounted on a base structure and the base structure is mounted on a platform for linear movement along the platform.

13. Apparatus as claimed in Claim 12, wherein the platform is a wheeled trailer and the length of the linear movement is such that in one position the booms lie substantially within the overall length of the platform.

14. Apparatus as claimed in Claim 12 or Claim 13, wherein the platform includes rails and the base structure has wheels which run on the rails.

15. Apparatus as claimed in any one of Claims 6 to 14, wherein the feed openings for the screw conveyors have mouths of adjustable areas to control the rate at which material is conveyed.

16. A method of loading bulk material, substantially as herein described with reference to the accompanying drawings.

17. Loading apparatus for loading bulk material into a shipping container, substantially as herein described with reference to the accompanying drawings.