Method for unloading a space and device for performing this method

Abstract: The invention provides a method for unloading a space (2) filled with bulk material (3) using at least one grab (15) supported by a chassis (5), wherein the chassis (5) is displaced in lengthwise direction of the space (2) and wherein the grab (15) is emptied above a cross conveyor (18), characterized in that the cross conveyor (18) is moved reciprocally each time relative to the chassis (5) between a receiving position situated beneath the grab (15) and a retracted position, while in the retracted position of the cross conveyor (18) the grab (15) is lowered into the space (2) and raised therefrom filled with material (3) and opened above the cross conveyor (18) in the receiving position of the cross conveyor (18). Long bites (K,L) of material are thus systematically removed each time from a hold (2) in transverse direction of the hold.

Description: The invention relates to a method as according to the preamble of claim 1. Such a method is known from EP-A-0 404 273. Herein, the hoisting frame which bears the grab is swivelled to a position above the cross conveyor after the grab has been lifted out of the space. A rapid movement of the hoisting frame is difficult to control such that uncontrolled swinging of the grab is prevented during the swivelling movement. A rapid movement of the hoisting frame is nevertheless desired in order to shorten the unloading cycle. It is often important in the case of spaces, particularly the holds of vessels, that they be unloaded as quickly as possible. To this end the invention provides a method as according to claim 1. The invention also relates to and provides a device as formulated in claim 2. DE-U-2712156 discloses in figure 8 a device wherein a grab is lifted and lowered when suspended at a stationary frame, while a receiving trough is displaced between a receiving position and a retracted position. Mentioned and other features of the invention will be elucidated in the description following hereinafter with reference to a drawing, in which: Fig. 1 shows a perspective view of the rear part of a preferred embodiment of a device according to the invention taking the form of a vessel; Fig. 2 shows on a larger scale portion II in fig. 1; Fig. 3-12 are schematic views of successive steps in performing the method according to the invention; Fig. 13 shows on a larger scale a cross section of a variant of the vessel of fig. 1. The vessel 1 comprises a hold 2 for receiving bulk material 3, for instance gravel, sand , coal, grain or other bulk material. The vessel 1 has an unloading device 4 comprising a chassis 5 which is guided by means of rails 6 in lengthwise direction of the hold 2. The wheels 7 are driven by electromotors or hydromotors 31. A hoisting frame 8 is supported by and fixedly connected to the chassis 5. The hoisting frame 8 comprises two inclining side beams 32 and two shores 33 which support the side beams 32 on two vertical columns 34, the top ends of which are connected to the inclining beams 32 by means of horizontal beams 35. The hoisting frame 8 is further completed by cross beams 36 and a winch support platform 37. A hoisting shaft 44 with pulleys 45 is mounted on the upper part of beams 32. A cross conveyor 18 is displaceable relative to the chassis 5 over rails 39 in lengthwise direction of the vessel 1 between a receiving position as shown in fig. 10 and a retracted position under the winch support platform 37 as shown in fig. 12. In the retracted position of the cross conveyor 18 the grab 15 suspended from the upper end of the hoisting frame 8 and operated by means of winches 11 and 12 of respectively the closing cables 13 and the hoisting cables 14 is situated adjacently of the cross conveyor 18 so that the grab 15 can be lowered into the hold 2. The grab 15 has a length k which is preferably slightly smaller than the breadth b of the hold 2. In the release position the grab 15 is located above the receiving means forming part of the cross conveyor 18 and consisting of an elongate trough 17 positioned transversely of the hold 2, which trough debouches above an endless conveyor belt 40 which pours the material via a discharge chute 19 onto a lengthwise conveyor 20 disposed alongside the hold. This pours the material via a discharge chute 22 onto an outboard transporting discharge conveyor 20. The grab 15 carries a number of ultrasonic pick-ups which signal when the distance of the opened grab 15 to the material 3 has reached a certain minimum distance. Because the grab 15 is suspended on two cables 14 arranged at a considerable mutual distance, the grab 15 remains properly positioned in transverse direction of the hold 2. The material 3 is picked up from the hold 2 in layers wherein an elongate bite 28 extending in transverse direction and formed as according to fig. 8 is picked up each time. The grab 15 has a well-presented bite 28 to handle with each following layer because the chassis 5, and therewith the biting grab 15, is disposed each time staggered a half bite 28 relative to the previous layer. The unloading method is automatically controlled by a computer. The chassis 5 is hereby displaced each time a bite breadth c after each bite 28 and in each case only one bite 28 is taken up and unloaded above the trough 17. After taking and lifting the bite 28, during the displacing of the cross conveyor 18 the chassis 5 is already being moved a step in the length of the bite breadth c so that the opened grab 15 immediately comes to lie at the correct position for the following bite 28. The successive method steps are depicted in fig. 3-12. During sailing the grab 15 is lowered into the trough 17 (fig. 3). When unloading of the vessel 1 begins the empty grab 15 is raised (fig. 4) and the cross conveyor 18 moved to the retracted position (fig. 5), while the chassis 5 is moved to that location above the hold where it is desired to begin unloading. The steps of fig. 7-12 are repeated optionally first manually and later automatically. Paying out of the closing and hoisting cables is stopped at the correct moment by ultrasonic pick-ups. The end of the layer is signalled by limit switches (not drawn) on the chassis when the head end walls 38 of the hold 2 are approached. The chassis 5 carries a cabinet 41 with units and control equipment in addition to a control cabin 42. Fig. 13 shows two grabs 15 which operate simultaneously and adjacent one another and which, in the case of a very broad hold 2, take from the hold 2 as it were a large bite each time consisting of pieces and simultaneously unload the material therefrom into a trough 17 of a cross conveyor 18 travelling reciprocally over the chassis 5. Use can optionally be made of more than two mutually adjacent grabs 15. The space for emptying may be any elongate, more or less rectangular storage space, in particular a hold of a vessel, but also a basin, tank, cellar or bunker, or even a channel for excavation, of which the soil for excavation can be seen as occupying a space for emptying.

Claims: Method for unloading a longitudinal space (2) filled with bulk material using at least one grab (15) supported by a chassis (5), wherein each time an elongate bite (28) of bulk material extending in transverse direction of the space (2) is taken from the space (2) using said at least one elongate grab (15), wherein said at least one elongate grab (15) is emptied above a cross conveyor (18) by being unloaded in an elongate trough (17) positioned transversaly of said space (2) above said cross conveyor (18), and by discharging said elongate trough (17) onto said cross conveyor (18), wherein said cross conveyor (18) is discharged onto a conveyor (20) disposed alongside said space (2) in longitudinal direction of said space (2), and wherein the chassis (5) is displaced in lengthwise direction of the longitudinal space (2), characterized in that the cross conveyor (18) together with said elongate trough (17) is moved reciprocally each time relative to said displaceable chassis (5) between a receiving position situated beneath said at least one elongate grab (15) and a retracted position, while in the retracted position of the cross conveyor (18) said at least one elongate grab (15) is lowered into the space and raised therefrom filled with material and opened above said cross conveyor (18) in the receiving position of said cross conveyor (18), and that said cross conveyor (18) in its receiving position, in its retracted position and during displacement between these positions extends through a free passage of a frame of said displaceable chassis 5. Device (1) for performing the method as claimed in claim 1, comprising an unloading device (4) which is disposed close to a longitudinal space (2), a chassis (5) that is displaceable in lengthwise direction of said longitudinal space (2) and is guided by means of rails (6), which displaceable chassis (5) via hoisting means (11, 12, 13, 14) bears at least one elongate grab (15), extending in transverse direction of said space, a cross conveyor (18) extending transversaly of said space (2), an elongate trough (17) positioned transversaly of said space (2) above said cross conveyor (18), and a longitudinal conveyor (20) disposed alongside said space (2) in longitudinal direction of said space (2), wherein said cross conveyor (18) unloads onto said longitudinal conveyor (20), characterized in that said cross conveyor (18) together with said elongate trough is displaceable relative to said displaceable chassis (5) between a receiving position situated beneath said at least one grab (15) and a retracted position and that the at least one elongate grab (15) is suspended on a hoisting frame (8) which is supported by the chassis (5), which has located adjacent to at least on of the both sides of the space (2) a free passage for the cross conveyor (18) enabling the path of movement of the cross conveyor (18) relative to the chassis (5). Device (1) as claimed in claim 2, characterized in that the space (2) is situated in a vessel (1). Device as claimed in claim 2 or 3, characterized in that the chassis (5) carries a control cabin 42.

Inventors: SCHIPPERS EDWARD HENDRIKUS SPL, SCHIPPERS, EDWARD HENDRIKUS SPLINTER
Applicants: NAT MECHANICAL HANDLING B V, NATIONAL MECHANICAL HANDLING B.V.
Application year: 1993
Main classification: B65G67
IPC codes: B63B27, B65G47, B66C17, B65G67