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(11) | EP 0 113 155 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Device for moving a pile of objects such as boxes or bags |
| (57) A device (1) for displacing a stack of objects such as boxes or bales comprising
a carrying frame (2), a supporting structure (3) for the stack connected with said
frame (2) and defining a supporting surface, a lifting device (4) engaging the carrying
frame by a lifting member, for example a hoisting cable (5), at a distance above the
supporting structure (3) and a push-off device (6) for the stack. The lifting member
(5) engages an engaging member (75) movable between a high and a low position, is
connected with the carrying frame (2) and coupled with energy storing means (74, 82)
receiving energy for the driving means (86) at least during a movement from the low
to the high position. |
[0001] The invention relates to a device for displacing a stack of objects such as boxes or bales comprising a carrying frame, a supporting structure for the stack connected with said frame and forming a carrying surface, a lifting device engaging the carrying frame by a hoisting member, for example a hoisting cable, at a distance above the supporting structure and a push-off device connected with the supporting frame comprising a pushing member movably guided by guide means along the supporting structure and driven by driving means and coming into contact with a side face of the stack.
[0002] Such a device is known from DE-A-1 816 653. Such a device is used, for example, for loading a ship. The objects piled on the supporting surface are pushed by the push-off device from the carrying surface in the ship's hold so that the stack as a whole is deposited in the hold. In this known device the driving means comprise a hydraulic aggregate having a hydraulic pump driven by an electric motor. The electric motor may be fed by electric current supplied externally through a cable or by an electric accumulator arranged in the carrying frame. In the event of external supply of electric current the required electric leads hinder the maniability of the device. The use of an accumulator also has disadvantages. The accumulator has to be periodically charged, for which purpose it has to be removed from the carrying frame and to be replaced by a freshly charged accumulator. Thus the device is temporarily out of use and loading has to be interrupted.
[0003] The invention has for its object to provide a device of the kind set forth in the preamble which does not exhibit said disadvantages.
[0004] In a device embodying the invention this is achieved in that the lifting member engages an engaging member, connected with the frame so as to be movable between a high and a low position and coupled with energy storing means receiving energy at least during a movement from the low to the high position. Thus electric or hydraulic ducts from the outside or a charging apparatus for charging an accumulator are not required. The energy for the driving means is obtained from a free stroke of the lifting member with respect to the frame. In this way a device is obtained which is fully independent of external energy supply so that it is little vulnerable and easy to use. The device can co-operate with any desired lifting device.
[0005] The energy storing means preferably comprise a hydraulic jack and a hydraulic accumulator coupled with the former. In this way a structurally effective embodiment of the device is obtained, which is resistant to rough handling.
[0006] A further advantageous development of the device embodying the invention is obtained when the engaging member comprises a lever journalled on the frame, the first lever arm being engaged by the lifting member and the second lever arm by the jack, the jack being connected with the lever and the frame in a manner such that in the low position the point of engagement of the lifting member is located considerably below the bearing and the point of engagement of the jack is substantially at the same distance from its end connected with the frame as the bearing, whereas in the high position the point of engagement of the lifting member is located substantially at the same height as the bearing and the point of engagement of the jack is located at a considerably different distance from its end connected with the frame than the bearing. This measure results in that at the beginning of the movement of the engaging member from the low to the high position a small transmission ratio between the movements of the of the lifting member and the jack is obtained. Consequently the higher becomes the pressure of the hydraulic fluid in the jack and the hydraulic accumulator, the higher will be the force exerted on the jack. In this way a minimum stroke of the engaging member is obtained so that an advantageous, compact construction can be obtained.
[0007] Moreover, by said measure it can be ensured that with an appropriate adjustment of the residual pressure in the hydraulic system the weight of the empty device is not sufficient to cause the engaging member to turn from the low to the high position so that in this situation the point of engagement of the lifting device is located nearer the fulcrum of the lever than in the loaded state of the device, in which the engaging member is in the higher position. In this way it can be ensured that both in the empty and the loaded state of the device the point of engagement of the lifting device is located substantially perpendicularly above the centre of gravity so that the device will invariably hang perpendicularly on the lifting device.
[0008] In order to cause the device to move with minimum resistance across the bottom or the stacked layers of bales or boxes, when the push-off device is actuated, the frame is provided with supporting wheels rotatable about a shaft extending transversely of the direction of movement of the pushing member at the end remote from the supporting structure. During, the pushing-off movement the wheels roll with minimum resistance along the underlying layer.
[0009] In order to limit the required stroke of the engaging member the hydraulic jacks of the push-off device may be single-acting. These hydraulic jacks can indeed push the stack off the carrying surface, but they cannot move back the pushing member. Pushing back the pushing member has then to be performed when the stack of objects is being deposited on the carrying surface. In particular this is done by pushing the stack of objects with the aid of a push-off device from a fork lift truck onto the carrying surface. In order to prevent that the whole device should be pushed away from the fork lift truck by the push-off device rather than only the pushing member thereof, a device in a preferred embodiment of the invention is characterized by a supporting frame that can be separately positioned on a loading site and is provided with supporting means supporting the carrying frame in a direction opposite the pushing-off direction and transferring forces to engaging means on the loading site. Prior to loading the carrying frame is positioned at the supporting frame, which then supplies sufficient counter-pressure for pushing the pushing member back into the rest position.
[0010] In a further development of the device embodying the invention the supporting frame comprises downwardly converging carrying frame guides co-operating with the supporting frame. The carrying frame can thus be moved by the lifting device very rapidly and in the correct position with respect to the supporting frame. The operator of the lifting device only need lower the carrying frame approximately above the supporting frame, the carrying frame guides ensure correct positioning.
[0011] In a further development of the invention the supporting frame comprises rearwardly converging pallet guides at its front end viewed in the pushing-off direction. The stack supplied from a fork lift truck onto a pallet can thus be advantageously and readily positioned in front of the carrying surface, after which the push-off device of the fork lift truck automatically moves the stack correctly onto the carrying surface. This results in the additional advantage that the device embodying the invention can be very rapidly loaded, which enables optimum use of the device.
[0012] Preferably at least one roller rotatable about a horizontal transverse shaft is arranged on the supporting frame at the foremost end viewed in the pushing-off direction. This roller ensures a satisfactory transfer of the stack of objects from the pallet supported by the fork lift truck onto the carrying surface of the device.
[0013] Further features and advantages of the device will become apparent from the following description of embodiments of the invention with reference to the accompanying drawings.
Fig. 1 is a perspective view of the device embodying the invention, some parts being partly broken away.
Figs. 2 to 4 illustrate perspectively the deposition of a stack of objects on a device embodying the invention.
Figs. 5 and 6 are perspective views of the device in a different embodiment of the invention in use.
Figs. 7 and 8 schematically show the low and the high position respectively of the engaging member of the device shown in Fig. 1.
Figs. 9 and 10 illustrate in side elevations the deposition of a stack of objects in a different manner on a device embodying the invention.
Fig. 11 is a fragmentary, perspective view of the supporting frame of the device shown in Figs. 9 and 10.
Fig. 12 shows a variant of the supporting frame of the device embodying the invention.
[0014] The device 1 embodying the invention comprises a carrying frame 2 with which is connected a supporting structure 3 forming a carrying surface. On the supporting structure 3 a stack of objects such as boxes or bales can be supported in the way to be described more fully with reference to the further Figures. The device 1 furthermore comprises a lifting device 4 formed in this embodiment by a hoisting crane (not shown), the lifting member of which formed by a hoisting cable 5 is coupled with the device 1.
[0015] With the frame 2 is connected a push-off device 6. The push-off device 6 comprises a pushing member 7 which is adapted to move on the supporting structure 3. During this movement the pushing member 7 is guided by guide means. These guide means comprise guide tracks 10 in the supporting structure 3, along which skids 11 of the pushing member can slide. The pushing member 7 is held in a vertical position by a guide arm 15 comprising two plates 16 and 18 pivoted to one another at 17. The plates 16 and 18 are connected by means of hinges 19, 20 with the pushing member 7 and beams 21, 22 of the frame 2 respectively. The axes defined by the hinges 17, 19 and 20 are parallel to one another. When slipped out the pushing member 7 is held in a vertical position by the guide arm 15. The pushing plate 6 is engaged on both sides in supports 14 by two sectional pushing arms 12. At their ends near the frame 2 the pushing arms 12 are each rigidly connected with a shaft 13 journalled in the frame 2. Owing to the rigid connection of the pushing arms 12 with the shaft 13 the pushing plate 6 is prevented from getting out of square.
[0016] Below the pushing member 7 has a recess 68 into which can extend a supporting, plate-shaped member. With the pushing member 7 are furthermore connected holding means 69 capable of retaining the plate-shaped member. The operation of these parts will become apparent from the description of Figs. 5 and 6.
[0017] The lifting member formed by the hoisting cable 5 engages an engaging member formed by a lever 75. This lever 75 is pivotally mounted in the carrying frame 2 by means of a bearing 76 and can move between a high and a low position. The end of the lever 75 opposite the engaging point 77 of the hoisting cable 78 is engaged at the pivotal point 79 by a hydraulic jack 74. The jack 74 has pivoted its other end 80 to the frame 2. The hydraulic jack 74 is coupled through ducts on the one hand with a reservoir 81 of hydraulic fluid and a hydraulic pressure accumulator 82. When the device 1 loaded with a stack of objects is lifted by the hoisting cable 5, first the lever 75 will turn about the bearing 76 before the frame 2 is lifted. The plunger of the jack 74 is pushed inwards and the displaced fluid is pressed into the pressure accumulator 82. In this way an amount of energy is stored, which is sufficient to actuate the push-off device 6. When the lever 75 has fully turned into its high position, in which the jack cannot be further pushed inwards or in which the lever 75 strikes a stop, the device 1 is lifted. When the device 1 is again put down, the lever 75 is turned back from its high position into its low position under the action of the weight of the hoisting cable 5 or with the aid of a spring (not shown). The jack 74 then draws in hydraulic fluid from the reservoir 81. As a matter of course for these operations the ducts between the reservoir 81, the jack 74 and the pressure accumulator 82 include the appropriate non-return valves.
[0018] The pressurized hydraulic fluid in the accumulator 82 can be supplied through the ducts 85 to the hydraulic jacks 86 for driving the push-off device. The ducts 85 include a two-position valve 83 by which an outward or an inward movement of the jack can be optionally actuated. By actuating the control-valve 84 the chosen movement of the jack 86 is started.
[0019] The proportions of the jack are chosen so that the displaced volume of hydraulic fluid is largely sufficient for fully pushing out or fully drawing in the jack 86. Moreover, the proportions are such that the produced pressure in the accumulator 82 is sufficient for displacing the stack of objects.
[0020] By switching the two-way valve 83 into the drawing-in position for the jack 86 and by opening the control-valve 84 the push-off device 6 is automatically drawn back when the device 1 is lifted.
[0021] Fig. 1 furthermore shows that supporting wheels 87 are arranged at the end of the frame 2 remote from the supporting structure 3. These supporting wheels 87 can rotate about a shaft 13, which is transverse of the direction of displacement of the push-off device 6. These supporting wheels 87 facilitate drawing the device 1 from beneath a positioned stack.
[0022] Figs. 7 and 8 schematically show the lever 75 of the device.l in the low and the high position respectively. In the low position shown in Fig. 7 the point of engagement 77 of the hoisting cable 5 is located considerably below the bearing 76 and the point of engagement 79 of the jack 74 is located substantially at the same distance from its end 80 connected with the frame as the bearing 76.
[0023] In the high position of the lever 75 shown in Fig. 8 the point of engagement 77 of the lifting member is located substantially at the same height as the bearing 76 and the point of engagement 79 of the jack 74 is located appreciably nearer the end 80 connected with the frame than the bearing 76. By this design it is ensured that an advantageous difference in leverage is obtained between the beginning of the lifting movement, that is to say, from the low position, and the end of the lifting movement i.e. near the high position. Figs. 7 and 8 clearly show that the ratio of the moment arms 91 and 92 of the work line 90 of the lifting force and the reactive force of the jack 74 respectively is materially lower than the ratio of the moment arms 93 and 94 in the high position. In the high position a given lifting force is thus opposite a considerably heavier reactive force than in the low position. This is advantageous because when depressing the jack 74 the counter-pressure and hence the reactive force increases. By using a lever, the proportions of which satisfy the above-mentioned locations of the respective points of engagement, the lifting effort is utilized to the optimum so that the stroke of the point of engagement 77 of the lifting force with respect to the frame is at a minimum.
[0024] By choosing the residual pressure in the system so high that the weight of the empty device 1 is not sufficient to turn the lever 75 from the position of Fig. 7 into that of Fig. 8, it can be ensured that the device 1 will be hanging in a perpendicular position both in the empty and in the loaded state. In the empty state the centre of gravity of the device is located further to the right than in the loaded state. Figs. 7 and 8 clearly show that the point of engagement of the lifting device is located further to the left in the empty state than in the loaded state.
[0025] Figs. 2 to 4 illustrate a potential method of depositing a stack of objects to be displaced on the supporting structure of a device embodying the invention. In these Figs. these objects are bags or bales.
[0026] The stack 40 of bags is supplied on a pallet 41 with the aid of a fork lift truck 42. This fork lift truck is provided with a tilting device 43 comprising a supporting plate 44 and a side support 45. The supporting plate 44 is moved into contact with the top side of the stack 40. As is shown in Fig. 3 the fork carrying the pallet 41 can tilt through 180° together with the supporting plate 44 and the side support 45. In the fully tilted situation shown in Fig. 4 the stack 40 bears on the supporting plate 44. The side support 45 serves to prevent the stack 40 from disengaging during the tilting movement. The lowermost stack 40 supported on the supporting plate 44 is pushed off the fork lift truck 42 onto the device 50 embodying the invention by means of a pushing device 46, which basically corresponds with the pushing device described with reference to Fig. 1. The fork lift truck 42 is moved for this purpose with the supporting plate 44 as far as to the supporting structure 51 of the device 50. By subsequently actuating the pushing device 46 the fork lift truck 42 is moved away from the device 50, whilst the supporting plate 44 is drawn away from beneath the stack. The pallet 41 remains lying on the fork 53 of the fork lift truck 42 so that it is directly available for reuse.
[0027] The device 50 thus provided with a stack of bags 40 is hoisted with the aid of the hoisting cable 52 to the desired place, where it is pushed off the device with the aid of the pushing device 54 of the device 50.
[0028] As is shown in Figs. 5 and 6 a device 55 embodying the invention may be advantageously provided with holding means 61 for retaining a plate-shaped element 59 located beneath the stack 60. The stack 60 can be supplied in the same manner as shown in Figs. 2 to 4. On the supporting structure of the device embodying the invention is first deposited such a plate 59 before the stack is deposited on the supporting structure. As an alternative the stack may be supplied already standing on such a plate, whilst with the aid of a fork lift truck with a push-off device it can be directly slipped with the plate onto the device embodying the invention. Fig. 5 shows that the device 55 is lowered into a hold 57 of a ship 56. The device 55 is deposited on a layer of bales 58 already lying in the hold 57. By actuating the pushing device 63 of the device 55 the stack 60 is shifted to its place or the device 55 is withdrawn from beneath the stack 60.
[0029] When unloading the bales the device 55 is positioned by means of the hoisting cable 64 at the place in front of a stack 60 standing on a plate 59. The pushing device 63 is moved by the driving means into its outward position, whilst the plate 59 can fall into a recess 62 on the underside of the pushing member. The holding means 61 are actuated so that the plate 59 is clamped tight to the pushing member. Subsequently the driving means of the pushing device 63 are switched on in the opposite sense so that the pushing member is slipped back onto the pushing device 55. The plate 59 is thus drawn onto the supporting structure 65. The device 55 with the stack 60 standing on it can be lifted by means of the hoisting cable 64 and be conducted out of the hold.
[0030] The device 101 embodying the invention shown in Figs. 9 and 10 comprises a carrying frame 102 with which a push-off device 103 is connected. In order to obtain a simple structure of the hydraulic system of the device 101 and to limit the stroke of the lever 105 the push-off device 103 comprises piston/cylinder devices 104, which are single-acting cylinders. At each stroke of the lever 105 the piston/cylinder connected herewith, but not shown need thus displace only such an amount of fluid as is necessary for pushing out once the piston/ cylinders 104 of the push-off device 103. The push-off device 103 is pushed back into its drawn-in position when the stack of objects 107 is deposited on the carrying frame 102. For this purpose the device embodying the invention furthermore comprises a supporting frame 106 in which the carrying frame 102 can be positioned by the lifting device and which retains said carrying frame 102. The supporting frame 106 is separately arranged on the loading site 109 and bears on the ground by rubber-clad feet 112. The rubber has such a high friction coefficient with respect to the surface of the loading site 109 that the forces involved in depositing the stack of objects 107 on the frame 102 do not cause a shift of the supporting frame. Figs. 9 and 10 show that the carrying frame 102 is positioned by the lifting device in the supporting frame 106. Subsequently a stack of objects 107 is supplied on a pallet 108 by means of a fork lift truck 110. This fork lift truck 110 is provided with a push-off device 111. As soon as the operator of the fork lift truck 110 has positioned the pallet 108 in front of the carrying frame 102, he actuates the push-off device 111 so that the stack 107 is shifted from the pallet 108 onto the carrying frame 102. The stack 107 pushes the push-off device 103 from the carrying frame 102 back into its drawn-in position. The wheel 113 of the carrying frame 102 bears on the guide face l14 of the supporting frame 106 so that the carrying frame 102 is not pushed away by the backward pressure on the pushing device 103. Fig. 11 shows in detail that the supporting frame 106 is provided with the above-mentioned carrying frame guide 114 and an opposite guide 115. These guides 114 and 115 are converging downwardly. Furthermore lateral guides 116 are provided, which are also converging in a downward direction. When the carrying frame 102 is lowered into the supporting frame 106, the carrying frame 102 is automatically positioned correctly. In a lateral direction the carrying frame 102 is positioned because side parts of said frame are guided by the lateral guides 116 in a direction of length by the cooperation of the wheels 113 of the carrying frame 102 with the guides 114 and 115.
[0031] The carrying frame guide 114 is formed by a side face of a box-shaped part filled with ballast 117. This ballast may be formed by concrete or metal waste or a combination thereof. Owing to the weight of the ballast l17 the maximum frictional force of the flat legs 112 with respect to the loading site is sufficiently high to withstand forces involved in operation. Fig. 11 shows that the supporting frame 106 is prolonged to the front and provided at the front with pallet guides 118. When the operator of the fork lift truck 110 is positioning the stack 107 on the pallet 108 in front of the supporting frame 106, the pallet guides 118 ensure that the pallet gets in straight line in front of the carrying farme 102. The stack 107 is thus correctly deposited on the carrying frame 102.
[0032] At the front end of the supporting frame 106 are provided guide rollers 119, which support the underside of the stack 107 when it is being shifted from the pallet 108 onto the carrying frame 102. An additional advantage is that potential problems due to height differences by tolerances of the height of the pallet 108 are avoided by the rollers 119.
1. A device (1) for displacing a stack of objects such as boxes or bales comprising
a carrying frame (2), a supporting structure (3) for the stack connected with said
frame (2) and defining a supporting surface, a lifting device (4) engaging the carrying
frame by a lifting member, for example a hoisting cable (5), at a distance above the
supporting structure (3) and a push-off device (6) connected with the carrying frame
(2) and comprising a pushing member (7) movably guided by guide means (10, 11) along
the supporting structure (3) and driven by driving means (86) and coming into contact
with a side face of the stack characterized in that the lifting member (5) engages
an engaging member (75) movable between a high and a low position and connected with
the carrying frame (2) and coupled with energy storing means (74, 82) receiving energy
for the driving means (86) at least during a movement from the low to the high position.
2. A device as claimed in claim 1 characterized in that the energy storing means comprise
a hydraulic jack (74) and a hydraulic accumulator (82) coupled with the former.
3. A device as claimed in claim 2 characterized in that the engaging member comprises
a lever (75) journalled on the carrying frame (2), a first lever arm being engaged
by the lifting member (5) and a second lever arm being engaged by the jack (74), the
jack being connected with the lever (75) and the carrying frame (2) in a manner such
that in the low position (Fig. 7) the engaging point (77) of the lifting member (5)
is located considerably below the bearing (76) and the point (78) of engagement of
the jack (74) is located substantially at the same distance from its end (80) connected
with the carrying frame as the bearing (76), whereas in the high position (Fig. 8)
the point (77) of engagement of the lifting member (5) is located substantially at
the same height as the bearing (76) whereas the point (79) of engagement of the jack
(74) is located at a considerably different distance from its end (80) connected with
the carrying frame than the bearing (76).
4. A device as claimed in anyone of the preceding claims characterized in that at
the end remote from the supporting structure (3) the carrying frame (2) is provided
with supporting wheels (87) rotatable about a shaft (13) extending transversely of
the direction of movement of the pushing member (7).
5. A device as claimed in anyone of the preceding claims characterized by a supporting
frame (106) adapted to be separately positioned on a loading site (109) and provided
with supporting means (114) supporting the carrying frame (102) in a direction opposite
the pushing-off direction and engaging means (112) transferring forces and engaging
the loading site (109).
.6. A device as claimed in claim 5 characterized in that the supporting frame (106)
comprises carrying frame guides (114, 115, 116) co-operating with the carrying frame
(102) and converging in downward direction.
7. A device as claimed in claim 5 or 6 characterized in that the supporting frame
(106) comprises at its foremost end, viewed in the pushing-off direction, rearwardly
converging pallet guides (118).
8. A device as claimed in anyone of claims 5 to 7 characterized in that at the foremost
end, viewed in the pushing-off direction, the supporting frame (106) is provided with
at least one roller (119) rotatable about a horizontal, transverse shaft.
9. A device as claimed in anyone of claims 5 to 8 characterized in that a ballast
(117) is arranged on the supporting frame (106) and the engaging means comprise horizontal,
flat elements (112) of material such as rubber having a high friction coefficient
with respect to the loading site (109).