EP3947221A1

EP3947221A1 - A pallet stacker

Info

Publication number: EP3947221A1
Application number: EP20782285.9A
Authority: EP
Inventors: Mikael LUND PEDERSEN
Original assignee: Hannemann Holding Aps
Current assignee: Hannemann Holding Aps
Priority date: 2019-03-29
Filing date: 2020-03-30
Publication date: 2022-02-09
Also published as: EP3947221A4; WO2020200383A1; DK201970193A1; DK180533B1

Abstract

Stacker for pallets, where the stacker (1) comprises a frame work (4) intended for disposition with tree side edges of a pallet (2) where the stacker (1) further comprises a lifting frame (9) which is driven by an electrical lifting mechanism, where the lifting frame (9) is moveable vertically up and down along the frame work (4), and where the lifting frame (9) comprises a gripper arrangement (14) driven by an electrical engagement mechanism, where each gripper arrangement (14) comprises at least one gripper plate (25) which is movable arranged between a position for engaging a pallet (2) and a position for disengaging a pallet (2), whereby the gripper arrangement is movably controlled by wobble plates (29).

Description

A PALLET STACKER

The present invention relates to a stacker for pallets, where the stacker is for stacking and unstacking pallets resting on each other in a vertical stack, where the stacker comprises a frame work with at least a first side, a second side and a back, where the frame work is intended for disposition with tree side edges of a pallet.

The present invention also relates to methods, a computer program product and the use of the said stacker.

PRIOR ART

Before the development of the present invention, it was known to store pallets in stacks as e.g. disclosed in EP0587929A1 where pallets are removed from or added to the bottom or top of an erectable stack which is vertically displaced in a three-sided frame by two hydraulic cylinders.

One of the disadvantages of this is the use of hydraulic cylinders as hydraulic systems are unwanted in many places due to environmental or hygiene issues.

Another one of the disadvantages of this known system is the lack of safety devices in order to prevent failures during operation. Hydraulic systems usually have hose break and/or stop valves to prevent the systems from collapsing.

Many stackers or pallet magazines are pneumatic, which in terms of energy is an even worse solution than hydraulics. Similarly, solutions with actuators are also known in many cases to result in short and/or poor durability. Regarding safety aspects in pneumatic systems, the systems are often dangerous due to the lack of safety arrangements.

JPH 11292287 A discloses another stacker for stacking pallet from bottom up, where the stacker comprises housing with a number of vertical bars extending in the vertical direction on the inner surfaces for guiding the stack of pallet during the lift. The stacker further comprises a lifting mechanism comprising a first motor for lifting the stack of pallets in the vertical direction using a belt transmission. The lifting mechanism further comprises a second motor for moving the grippers into and out of engagement with the respective pallet. The grippers are spring-loaded and coupled to a wire connected to a winch unit driven by the second motor. The grippers are moved into and out of engagement by operating the winch unit. This solution includes a lot of moving parts that are subjected to wear and requires regular maintenance to prevent failures during operation.

The present invention differs from the prior art technology by using clean energy in terms of electricity and in having anti-crash devices ensuring that no harm is done to neither pallets nor stacker.

OBJECT OF THE INVENTION

The object of this invention is therefore to provide a stacker of the type mentioned in the introduction which uses clean energy in terms of electricity making it useable in a wide range of industries.

It is a further object of the invention to provide a stacker which improves the working environment e.g. due to far less noise than pneumatic and hydraulic systems.

It is an even further object of the invention to provide a stacker with anti-crash devices ensuring that no harm is done to pallets or stacker. DESCRIPTION OF THE INVENTION

According to a first aspect of the invention, the above object is achieved with a stacker of the type mentioned in the introduction, where the stacker further comprises a lifting frame with at least a first side, a second side and a back which is driven by an electrical lifting mechanism, where the lifting frame is moveable vertically up and down along the frame work, and where the lifting frame at the first side and the second side comprises a gripper arrangement driven by an electrical engagement mechanism, where each gripper arrangement comprises at least one gripper plate which is movable arranged between a position for engaging a pallet and a position for disengaging a pallet.

This makes it possible to operate a stacker only using clean energy where the stacker is able to conduct a method of stacking and unstacking pallets.

In a preferred embodiment, the stacker is an integrated safety-shielded unit where the vast majority of moving parts are not accessible during operation due to the use of cover plates. This increases the safety for the worker operating the stacker and reduces the area around the stacker that need to be shielded.

In another aspect, the present invention also relates to a stacker, where the first side and the second side of the lifting frame comprises a wall part, where the wall part at the first side is facing the wall part at the second side and where the wall parts are disposed at opposite side edges of a pallet.

This makes it possible to hold the pallets at two side edges between the wall parts when stacking and unstacking, hence avoiding the sliding of pallets up and down the sides of the frame work. In a preferred embodiment, the top of the wall parts is at least the same as the top of the stacker.

The stacker may further comprise a bottom area arranged below the frame work and substrate on which the stacker is placed. One or more support elements, e.g. legs, configured to support the stacker may extend into this bottom area. The support elements may be adjustable, e.g. telescopic, for adjusting the height of the bottom area and thus the total height of the stacker. The lifting frame may be moved into this bottom area for engagement or disengagement with one or more pallets during stacking and unstacking.

In another aspect, the present invention also relates to a stacker, where the electrical lifting mechanism comprises a transmission mechanism driven by an electrical motor, where the electrical motor is connected to the frame work and where the transmission mechanism is connected to the lifting frame, the transmission mechanism being able to transform rotational motion of the electrical motor into linear motion of the lifting frame.

This makes it possible to lift and lower the lifting frame in a preferred embodiment by means of a transmission mechanism driven by an electrical motor.

The transmission mechanism may be connected directly to the drive shaft of the motor, or via a gear unit. This allows the transmission mechanism to be directly driven by the electrical motor.

The transmission mechanism may alternatively be indirectly driven by the electrical motor via a toothed chain or belt passing over at least two sprockets. Other embodiments based on friction could also be alternatives, such as a V- belt, a flat belt, a grooved belt or a ribbed belt. The rotational motion may be either clockwise or anticlockwise, and it may change between clockwise and anticlockwise in any way. The rotational motion may also run "endlessly" meaning that a cycle can be run on a lap in the same direction either clockwise or anticlockwise.

The transmission mechanism may be a winch system with a cable or wire wound around a drum. The wire or cable may pass through one or more pulleys before being connected to the lifting frame. The electrical motor may be used to drive the winch system in the clockwise or anticlockwise direction which in turns allows the lifting frame to be lifted or lowered.

The transmission mechanism may alternatively comprise a connecting rod or link having a first end and an opposite second end. The first end may be connected to a sprocket. The second end may be connected to the lifting frame.

The sprocket may be driven around an axle on which axle an optional plate/wheel/disk also may be situated and where between the sprocket and the plate/wheel/disk the first end of the shaft is connected off-centre relative to the sprocket and/or the plate/wheel/disk to ensure a rotational motion of the first end.

In an alternative embodiment, the first end of the shaft could be arranged at the periphery of the sprocket and/or the plate/wheel/disk, which would also ensure the rotational motion of the first end.

Alternatively, the frame work may comprise a wheel configured to move along a track or guide rail on the lifting frame during lifting or lowering of the lifting frame, or vice versa. The wheel may be rotatable arranged on an axle on the frame work or lifting frame. The track or guide rail may be formed as an endless track or guide rail, e.g. a ring or disk. The track or guide rail may be connected to a sprocket driven by the electrical motor, e.g. via the gear unit. The track or guide rail may follow the rotation of a sprocket driven by the electrical motor, e.g. via the gear unit. The track or guide rail may be arranged on the same drive shaft at a distance from each other. Alternatively, the track or guide rail may be directly connected to or be arranged on the sprocket. The track or guide rail may be positioned off-centre to the sprocket, or vice versa.

In another aspect, the present invention also relates to a stacker, where the transmission mechanism is connected to the lifting frame via a crash-safe connection, the crash-safe connection being configured to enable the transmission mechanism to move relative to the lifting frame in the event that the movement of the lifting frame is blocked.

The transmission mechanism is preferably connected to the lifting frame via a crash-safe connection. This makes it possible to avoid crashing of the electrical lifting mechanism, either in a direct connection with the lifting frame or in an indirect connection with the lifting frame.

In example, the second end of the connecting rod is connected to the lifting frame in a crash-safe bolt-slot connection, where at least one bolt is able to move within a slot if the lifting frame is blocked. As the transmission mechanism is moved in the opposite direction, the bolts may optionally slide back into their initial positions or remain in their new positions.

In a preferred embodiment the slot is in the connecting rod and closer to the second end than the first end. The bolt/bolts are thus passing through the slot in the connecting rod and the bolts are connected to the lifting frame.

Using an indirect connection the slot is in the connecting rod which is in the middle of the connection, where at one or both sides of the connecting rod there is a distance part and then another connecting rod which is connected with the rest of the lifting frame in a rotary joint.

In a further preferred embodiment the bolts are secured and tensioned at both sides of the connecting rod to the lifting frame via coupling means, where the coupling means being able to conduct rotational motion on the lifting frame and being able to conduct linear motion at the crash-safe bolt-slot connection.

In another example, the above mentioned wheel may remain in contact with the track or guide rail during lifting or lowing of the lifting frame. In the event of a blockage, the wheel may move out of contact with the track or guide rail and thus allow the lifting frame to move relative to frame work. As the lifting frame is moved in the opposite direction, the wheel is brought back into contact with the track or guide rail.

It is also possible to avoid crashing of the electrical lifting mechanism by means of a sensor which sends signal to the control for stopping the machine in case of a blocking occurs. The sensor may be arranged on the transmission mechanism or be positioned relative to transmission mechanism so that it can detect any blockage, e.g. by a non-contact measurement.

In an optimal solution, the stacker is equipped with both the sensor crash-safe arrangement and the bolt-slot crash-safe arrangement.

In the present invention, the electrical engagement mechanism is arranged at the lifting frame and the electrical engagement mechanism comprises a sprocket driven by an electrical motor and gear unit, where the sprocket is arranged at a rod where a wobble plate is connected to a gripper arrangement at both the first side and at the second side of the lifting frame. This makes it possible to operate the gripper arrangements between a grip (engaging position) and a non-grip position (disengaging position) ensuring that the gripper arrangement at either side is in the same grip or non-grip position. This provides a more reliable and robust means of engagement compared to the winch system of JPH 11292287 A. This in turn reduces the risk of a failure and saves costs as the total number of moving parts is reduced.

In a preferred embodiment the sprocket is driven by the transmission mechanism which in turn is driven by the electrical motor.

An alternative embodiment could be a pulley driven by a toothed belt which is driven by an electrical motor.

An even further alternative embodiment could be a V-belt pulley driven by a belt which is driven by an electrical motor. Other embodiments based on friction could also be alternatives. In an even further embodiment a wheel could be directly driven by a motor and gear unit.

The rotational motion may be either clockwise or anticlockwise, and it may change between clockwise and anticlockwise in any way.

The use of electrical motors improves the working environment and reduces the noise level during operation as no pneumatic or hydraulic systems are required. Further, the use of electrical motors for lifting and engagement does not require hydraulic or pneumatic drive systems and additional safety devices to prevent a collapse during operation.

In another aspect, the present invention also relates to a stacker, where the gripper arrangement comprises at least one gripper plate which is movable arranged between a position for engaging a pallet and a position for disengaging a pallet, where the gripper arrangement comprises a first wheel for moving the gripper plate into position for engaging a pallet and a second wheel for moving the gripper plate into position for disengaging a pallet, where the gripper plates are movable about an axis of rotation and where the first wheel and the second wheel are placed at opposite sides of the wobble plate arranged at the rod and where at least one of the first and second wheels is spring-loaded.

This makes it possible to avoid crashing of the electrical engagement mechanism, because the spring-loaded wheel(s) is/are forced out of its initial position in case there is a blockage of the gripper arrangement, that is, if the gripper arrangement is not able to move into position for engagement. A blockage of the gripper could happen in case a pallet was not yet brought into its final position in the stacker or a pallet has been incorrectly positioned within the stacker. The electrical engagement mechanism may then be reset and the wheel(s) return(s) to its initial position due to the force exerted by the spring.

One or more springs may be connected to the first and/or second wheel and further to one or more fixed positions on the gripper arrangement, e.g. on a connecting member between the wheel(s) and a lifting frame. Alternatively, the first and second wheels may be coupled to the lifting frame or connecting member by means of a spring-loaded scissor mechanism. Other spring-loaded safety mechanism may be used.

It is also possible to avoid crashing of the electrical engagement mechanism by means of a sensor which sends signal to the control for stopping the machine in case of a blocking occurs. The sensor may be arranged on the engagement mechanism or be positioned relative to engagement mechanism so that it can detect any blockage, e.g. by a non-contact measurement.

In an optimal solution, the stacker is equipped with both the sensor crash-safe arrangement and the spring-loaded crash-safe arrangement. In another aspect, the present invention also relates to a stacker, where the lifting frame further comprises ball bearings arranged perpendicular to each other in pairs suitable to move vertically up and down joints provided between the first side, the back and the second side of the frame work, where at least two pairs of ball bearings are arranged at either joint.

This makes it possible to ensure a fully controlled vertical movement along the frame work, where the lifting frame cannot get out of track and cause a stand-still of the stacker.

In a preferred embodiment there are two pairs of ball bearings arranged at either joint, where the pairs are at approximately the same horizontal level and further there are two pairs of ball bearings arranged at either joint vertical below each other. Hence, there are optimally four pairs of ball bearings ensuring a controlled movement.

In another aspect, the present invention also relates to a method of stacking pallets in the stacker described earlier, where the stacking at least comprises the following steps:

• at least one pallet is moved into a correct position in the stacker,

• the lifting frame is driven to a disengaging position where at least one pre- loaded pallet is resting on the at least one pallet to form a stack,

• the gripper plates are moved into a disengaging position,

• the lifting frame is further driven to a bottom position,

• the gripper plates are further moved into an engaging position with a lower pallet of the stack,

• the lifting frame is driven to a top position.

With this method it is possible to use the above mentioned stacker to lift the lower pallet of the stack one or more pallet heights and into a top position for enabling upstacking of pallets, e.g. to build up the stack from beneath. The process can be repeated to until a desired stack height has been achieved or until all pallets have been stacked.

During stacking, the stacker may be preloaded with a pallet or a stack of pallets arranged between the first and second sides of the lifting frame.

Initially, the lifting frame with the preloaded pallet(s) is driven into a top position, if it is not already placed in that position. Then a pallet or stack of pallets are moved into position in the bottom area of the stacker. The lifting frame is afterwards driven to a disengaging position where the preloaded pallet(s) is/are resting on the pallet or stack of pallets placed in the bottom area, thereby forming a combined stack of pallets. The gripper plates are moved out of engagement with the preloaded pallet or a lowest pallet of the preloaded stack and into the disengaging position. The lifting frame is then driven to a bottom position. Subsequently, the gripper plates are moved into engagement with the lowest pallet of the combined stack. The lifting frame with the combined stack is finally driven back to the top position, or an alternative top position. The stacker may then await the next pallet or stack of pallets.

If the pallets and/or stacks of pallets are feed continuously to the stacker, then the stacking can be performed into a continuous process. Alternatively, the stacking process can be run each time a pallet or stack of pallets is fed to the stacker, or when the worker manually activates the stacker. This allows the stacker to be implemented in existing production lines, or as a stand-alone unit.

In an alternative embodiment, once the gripper plates are driven out of engagement with the preloaded pallet or a lowest pallet of the preloaded stack, the lifting frame may be driven to back to the top position, or a starting position, instead of the bottom position. The combined stack may thus be resting on the substrate, e.g. a floor, instead of being held in an elevated position within the stacker. In a further alternative embodiment, the preloaded pallet or stack of pallets may be resting on the substrate instead of being held in the top position by the lifting frame. The lifting frame may be driven to the bottom position. The gripper plates are then moved into engagement with the preloaded pallet or the lowest pallet of the preloaded stack. The lifting frame with the preloaded pallet(s) is then driven back to the top position.

In another aspect, the present invention also relates to a method of stacking pallets in the stacker described earlier, where the stacker is pre-loaded by:

• at least one further pallet is moved into a correct position in the stacker,

• the lifting frame is driven to the bottom position,

• the gripper plates are moved into an engaging position with the at least one further pallet,

• the lifting frame is driven to the top position.

With this method it is possible, to place the stacker in a starting position when the stacker is not stacking or downstacking, or when the stacker is empty. In starting position, the lifting frame is driven to the starting position where the lifting frame is positioned within the frame work. The gripper plates are moved into the disengaging position.

If the stacker is empty, the lifting frame may be in the starting position, as mentioned above. The gripper plates may be moved into the disengaging position, if they are not already in that position. One or more pallets are moving into position within the bottom area. The lifting frame is driven to the bottom position. The gripper plates are moved into engagement with the lowest pallet. The lifting frame with the one or more pallets is driven to the top position. The stacker is now preloaded and the stacking can be repeated as mentioned earlier. In another aspect, the present invention also relates to a method of downstacking pallets in the stacker as described above, where the downstacking at least comprises the following steps:

• lifting frame is driven to a bottom position,

• gripper plates are moved out of an engaging position with a lowest pallet of the stack of pallets and into a disengaging position,

• lifting frame is driven to an engaging position relative to another pallet of the stack, e.g. a second lowest pallet,

• gripper plates are moved into the engaging position with the another pallet,

• lifting frame is driven to a top position,

• removing at least the lowest pallet from the stacker.

With this method it is possible to use the stacker to engage a second lowest pallet of a stack for lifting a pallet and those pallets, which are situated above the pallet, at least one pallet height, to enable the removal of the lowest pallet of the stack and thus downstacking from beneath.

During downstacking, the stacker is preloaded with a pallet or a stack of pallets arranged between the first and second sides of the lifting frame. The pallet(s) may either be held in the top position by the lifting frame or be resting on the substrate.

Initially, the lifting frame is driven to the bottom position so that the preloaded pallet(s) is/are resting on the substrate. The gripper plates are moved out of engagement with the lowest pallet and into the disengagement position. The lifting frame is driven to an engagement position relative a selected pallet located above the lowest pallet. The selected pallet may be the second or third lowest pallet. The gripper plates are moved into engagement with the selected pallet. The lifting frame is driven back to the top position. Finally, the pallet(s) located on the substrate is/are removed. The process may be repeated until all pallets have downstacked and removed.

In an alternative embodiment, the preloaded pallet(s) is/are already resting on the substrate and the lifting frame is in the starting or top position. The lifting frame is driven to the engagement position. The gripper plates are then moved into engagement with the selected pallet. The lifting frame with a reduced stack of pallet is driven back to the top position. Finally, the remaining pallet(s) resting on the substrate is/are removed. The process may be repeated until all pallets have downstacked and removed.

In the alternative embodiment, the lifting frame may further be driven to the bottom position so that the reduced stack is resting on the substrate. The gripper plates are moved out of the engagement with the lowest pallet. Finally, the lifting frame is driven back to the top or stacking position. This may be desired if the stacker is used as a stand-alone unit.

During downstacking, the lowest pallet may also be placed on top of another pallet(s) already positioned in the bottom area. The lifting frame is then raised one or more pallet heights and the gripper plates are moved into engagement with a selected pallet. The lifting frame is thereafter driven to the top position and the stack of pallets is removed from the bottom area. This may be desired if the worker need to add one or more pallets to an existing pallet or stack of pallets.

In another aspect, the present invention also relates to a method of placing a stack of pallets in the stacker described above, where the placing of a stack at least comprises the following steps:

• a stack of pallets is correctly positioned within the stacker on the substrate,

• the lifting frame is driven to a bottom position, • the gripper plates are moved into an engaging position with a lowest pallet of the stack,

• the lifting frame is driven to a top position.

With this method it is possible to use the stacker to lift the lower pallet one or more pallet heights as desired to enable placing a stack of pallets, when building up the stack from beneath. The above method may also be used to preload the stacker.

If the stacker is empty, a stack of pallets is initially moved into position in the bottom area of the stacker. The lifting frame is driven to the bottom position. The gripper plates are moved into engagement with the lowest pallet of the stack. The lifting frame with the pallets is optionally driven to the top position.

If the stacker is already preloaded, the lifting frame with the preloaded pallet(s) is/are optionally driven to a second (higher) top position located above a first (lower) top position. The stack of pallets is moved into position in the bottom area of the stacker. The lifting frame is driven to an engagement position where the preloaded pallet(s) is/are resting on the stack of pallets. The gripper plates are moved out of engagement with the lowest pallet of the upper (preloaded) stack and into the disengagement position. The lifting frame is further driven to the bottom position. The gripper plates are then moved into engagement with the lowest pallet of the combined stack. The lifting frame with the combined stack is optionally driven to the top position.

This allows for a quick and simply method of loading pallets into the stacker before starting the downstacking.

In another aspect, the present invention also relates to a method of removing a stack of pallets in the stacker described above, where the removal of a stack at least comprises the following steps: • the lifting frame is driven in a bottom position,

• the gripper plates are moved out of engagement with a lowest pallet of a preloaded stack and into a disengaging position,

• the lifting frame is driven to a top position,

• the stack is moved from the stacker.

With this method it is possible to use the stacker to engage a lowest pallet of an upper stack for lifting that pallet and those pallets, which are situated above the pallet, at least one pallet height, to enable the removal of a lower stack of pallets and thus downstacking from beneath. The above method may also be used to remove the entire stack from the stacker.

When removing the stack, the lifting frame with a preloaded stack of pallets is initially driven to the bottom position. The gripper plates are moved out of engagement with the lowest pallet of the preloaded stack and into the disengagement position. The lifting frame is driven back to the top or starting position. Finally, the stack is removed from the stacker.

When removing a sub-stack of pallet, the lifting frame with a preloaded stack of pallets is initially driven to the bottom position. The gripper plates are moved out of engagement with the lowest pallet of the preloaded stack and into the disengagement position. The lifting frame is driven to an engagement position relative to a lowest pallet of an upper stack of pallets. The gripper plates are moved into engagement with that lowest pallet of the upper stack. The lifting frame is driven further back to the top position. Finally, the lower stack of pallets is removed from the stacker.

Optionally, the lifting frame is driven back to the bottom position where the lowest pallet of the upper stack of pallets is resting on the substrate. The gripper plates are moved out of engagement with that lower pallet and into the disengagement position. The lifting frame is driven back to the top or starting position. In another aspect, the present invention also relates to a computer program product comprising instructions to cause the stacker described above to execute the steps of the methods.

This makes it possible to automate the various methods described above and thus to obtain a better and more efficient utilisation of the stacker capability. The stacker may be operated automatically using a controller where the pallets are at least automatically feed to and stacked in the stacker. Alternatively or additionally, the pallets may be automatically downstacked and removed from the stacker. This allows for stacker to be implemented in a fully-automated or semi-automated production line.

The controller may be implemented as a PLC or a microprocessor and may be electrically connected to a user interface, e.g. a touch-screen or user terminal. Further, the controller may be electrically connected to the various sensors within the stacker, thereby allowing for a worker to monitoring the operating status and/or manually operate of the stacker.

Optionally, one or more sensors, e.g. distance sensors or cameras, may be used to detect when one or more pallets are being fed to the stacker. The controller may then use the sensor signal(s) to activate the stacker, or when receiving an external signal or command from an external sensor or controller. This allows for the stacker to be coupled to an external transport or conveyor system.

In another aspect, the present invention also relates to the use of a stacker described above for pallets having a standardised size and shape.

This makes it possible to stack and unstack pallets categorized as CHEP (Commonwealth Handling Equipment Pool) which is a well-defined size of pallets. However, the stacker could be constructed to handle any other kind of square or rectangular shaped pallets. Preferably, at least the internal length and width of the lifting frame may be adaptable so that it can be adjusted to handle pallets of different sizes.

DRAWING

The invention will be described in further details below by means of non-limiting embodiments with reference to the drawing, in which:

Fig. 1 a-1 g show a stacker according to the invention in different views,

Fig. 2a-2b show the stacker in perspective,

Fig. 3 shows the stacker where the covering is removed and the lifting frame etc. is visible

Fig. 4a-4d show the lifting frame of the stacker in different views and with different details

Fig. 5a-5d show the gripper arrangement of the stacker in various positions, Fig. 6a-6d show the gripper arrangement of the stacker in engaging and disengaging positions.

In the drawing, the following reference numerals have been used for the designations used in the detailed part of the description:

1 Stacker

2 Pallet

3 Stack

4 Frame work

5 First side, frame work

6 Second side, frame work

7 Back, frame work 8 Sideedge, pallet

9 Lifting frame

10 First side, lifting frame

11 Second side, lifting frame

12 Back, lifting frame

13 Electrical lifting mechanism

14 Gripper arrangement

15 Electrical engagement mechanism

16 Wall part

17 Sprocket

18 Electrical motor and gear unit

19 Shaft

20 First end, shaft

21 Second end, shaft

22 Bolt-slot connection

23 Bolt

24 Slot

25 Gripper plate

26 Sprocket

27 Electrical motor and gear unit

28 Rod

29 Wobble plate

30 First wheel

31 Second wheel

32 Spring

33 Ball bearings

34 Pair, ball bearings

35 Joint

36 Coupling means

37 Axis of rotation

38 Chain, Electrical lifting mechanism 39 Chain, Electrical engagement mechanism

40 Front

41 Above

42 Base

43 Coverplates

44 Frame, Gripper arrangement

45 Axis, Lifting frame

DETAILED DESCRIPTION OF THE INVENTION

A stacker according to the invention is shown in Figure 1 -6.

Figures 1 a-1 g show the stacker 1 for pallets 2 in different views, where the stacker 1 is shown with cover plates 43, where figure 1 a shows the stacker 1 from the back 7, figure 1 b shows the stacker 1 from the first side 5, figure 1c shows the stacker 1 from the front 40, figure 1 d shows the stacker 1 from the second side 6, figure 1 e shows the stacker 1 from a perspective view from the first side 5 in which two pallets 2 are resting on each other in a vertical stack 3, figure 1f shows the stacker from above 41 where the side edges 8 of the pallet 2 is visible and figure 1g shows the stacker 1 from a perspective view from the second side 6 in which two pallets 2 are resting on each other in a vertical stack 3.

Figures 2a-2b show the stacker 1 in perspective, where figure 2a shows the stacker 1 where the base 42 is separated from the rest of the stacker 1 , where the stacker 1 is seen from the second side 6 and the back 7 and where the stacker 1 is covered by cover plates 43. Figure 2b shows the stacker 1 without cover plates 43 and where part of the frame work 4 is visible and where the lifting frame 9 is also shown. Figure 3 shows the stacker 1 where the covering/cover plates 43 are removed and the lifting frame 9 is also visible. The figure also shows the electrical lifting mechanism 13 which drives the lifting frame 9 vertically up and down along the frame work 4, where the electrical lifting mechanism 13 comprises a sprocket 17 driven by an electrical motor and gear unit 18 and connected with a chain 38, where the sprocket 17 is connected to a shaft 19 with a first end 20 being off- centre of the sprocket 17 and where a second end 21 of the shaft 19 is connected to the lifting frame 9, where the first end 20 is able to conduct a rotational motion and the second end 21 of the shaft 19 is able to conduct a linear motion.

Figure 3 also shows that the second end 21 of the shaft 19 is connected to the lifting frame 9 in a crash-safe bolt-slot connection 22, where at least one bolt 23 is able to move within the slot 24 if the lifting frame 9 is blocked. In the shown embodiment the bolts 23 are secured and tensioned at both sides of the shaft 19 to the lifting frame 9 via coupling means 36, where the coupling means 36 are able to rotate around an axis 45 on the lifting frame 9 and being able to conduct linear motion at the crash-safe bolt-slot connection 22. Figure 3 further shows the joints 35 provided between the first side 5, the back 7 and the second side 6 of the frame work 4.

Figures 4a-4d show a lifting frame 9 in different views and with different details, where the lifting frame 9 at figure 4a is shown with a first side 10, a second side 11 and a back 12, figure 4b shows that the first side 10 and the second side 11 of the lifting frame 9 comprises a wall part 16, where the wall part 16 at the first side 10 is facing the wall part 16 at the second side 11 , where the wall parts 16 are disposed at opposite side edges 8 of a pallet 2.

Figure 4c shows a detail from figure 4a where ball bearings 33 are arranged perpendicular to each other in pairs 34 being suitable to move vertically up and down joints 35 (see figures 2b and 3) of the frame work 4, where at least two pairs 34 of ball bearings 33 are arranged at either joint 35.

Figure 4d shows a perspective view of a lifting frame 9 where at the second side 11 a gripper arrangement 14 is visible and which is driven by an electrical engagement mechanism 15. The electrical engagement mechanism 15 comprises a sprocket 26 driven by an electrical motor and gear unit 27 and connected with a chain 39, where the sprocket 26 is arranged at a rod 28. The figure also shows that a wobble plate 29 is connected to the gripper arrangement 14 at both the first side 10 and at the second side 11 of the lifting frame 9.

Figures 5a-5d show the gripper arrangement 14 in various positions, figure 5a shows the gripper arrangement 14 from the front with gripper plates 25 which are movable controlled by the wobble plates 29 around the axis of rotation 37, figure 5b shows the gripper arrangement 14 from above, figure 5c shows the gripper arrangement 14 in perspective.

Figure 5d shows the gripper arrangement 14 from below where it is shown that the gripper arrangement 14 comprises a first wheel 30 for moving the gripper plate 25 into position for engaging a pallet 2 and a second wheel 31 for moving the gripper plate 25 into position for disengaging a pallet 2, in that the gripper plates 25 are movable about the axis of rotation 37 (shown e.g. at figure 5c) and where the first wheel 30 and the second wheel 31 is placed at opposite sides of the wobble plate 29 arranged at the rod 28 and where the first wheel 30 via a spring 32 is spring-loaded.

Figures 6a-6b show the gripper arrangement 14 in engaging positions where the gripper plates 25 are substantially in horizontal position and the frame 44 is substantially in vertical position, where figure 6a shows the gripper arrangement 14 from the back and figure 6b shows the gripper arrangement 14 in perspective, and figure 6c-6d show the gripper arrangement 14 in disengaging positions where the distance between the frame 44 closer to the two axis of rotation 37 are shorter than the distance between the frame 44 closer to the gripper plates 25, where figure 6c shows the gripper arrangement 14 from the back and figure 6d shows the gripper arrangement 14 in perspective.

The figures show that each gripper arrangement 14 comprises two gripper plates 25 which depending on the position of the wobble plates 29 are movable arranged between a position for engaging a pallet 2 as shown at figures 6a-6b and a position for disengaging a pallet 2 as shown at figures 6c-6d.

Claims

P A T E N T C L A I M S

1. A stacker (1 ) for pallets (2), where the stacker (1 ) is for stacking and unstacking pallets (2) resting on each other in a vertical stack (3), where the stacker (1 ) comprises a frame work (4) with at least a first side (5), a second side (6) and a back (7), where the frame work (4) is intended for disposition with tree sideedges (8) of a pallet (2) the stacker (1 ) further comprises a lifting frame (9) with at least a first side (10), a second side (11 ) and a back (12) which is driven by an electrical lifting mechanism (13), where the lifting frame (9) is moveable vertically up and down along the frame work (4), and where the lifting frame (9) at the first side (10) and the second side (11 ) comprises a gripper arrangement (14) driven by an electrical engagement mechanism (15), where each gripper arrangement (14) comprises at least one gripper plate (25) which is movable arranged between a position for engaging a pallet (2) and a position for disengaging a pallet (2), characterized in that the electrical engagement mechanism (15) is arranged at the lifting frame (9) and where the electrical engagement mechanism (15) comprises a sprocket (26) driven by an electrical motor and gear unit (27), where the sprocket (26) is arranged at a rod (28) where a wobble plate (29) is connected to a gripper arrangement (14) at both the first side (10) and at the second side (11 ) of the lifting frame (9).

2. A stacker (1 ) according to claim 1 , characterized in that the first side (10) and the second side (11 ) of the lifting frame (9) comprises a wall part (16), where the wall part (16) at the first side (10) is facing the wall part (16) at the second side (11 ) and where the wall parts (16) are disposed at opposite side edges (8) of a pallet (2).

3. A stacker (1 ) according to any of claims 1 and 2, characterized in that the electrical lifting mechanism (13) comprises a transmission mechanism driven by an electrical motor and gear unit (18), where the electrical motor and gear unit (18) are connected to the frame work (4) and where the transmission mechanism is connected to the lifting frame (9), the transmission mechanism being able to transform rotational motion of the electrical motor into linear motion of the lifting frame (9).

4. A stacker (1 ) according to claim 3, characterized in that the transmission mechanism is connected to the lifting frame (9) via a crash-safe connection, the crash-safe connection being configured to enable the transmission mechanism to move relative to the lifting frame (9) if the movement of the lifting frame (9) is blocked.

5. A stacker (1 ) according to any of the claims 1 to 4, characterized in that the gripper arrangement (14) comprises at least one gripper plate (25) which is movable arranged between a position for engaging a pallet (2) and a position for disengaging a pallet (2), where the gripper arrangement (14) comprises a first wheel (30) for moving the gripper plate (25) into position for engaging a pallet (2) and a second wheel (31 ) for moving the gripper plate (25) into position for disengaging a pallet (2), where the gripper plates (25) are movable about an axis of rotation (37) and where the first wheel (30) and the second wheel (31 ) are placed at opposite sides of the wobble plate (29) arranged at the rod (28) and where at least one of the first and second wheels (30, 31 ) is spring-loaded.

6. A stacker (1 ) according to any of the claims 1 to 5, characterized in that the lifting frame (9) further comprises ball bearings (33) arranged perpendicular to each other in pairs (34) suitable to move vertically up and down joints (35) provided between the first side (5), the back (7) and the second side (6) of the frame work (4), where at least two pairs (34) of ball bearings (33) are arranged at either joint (35).

7. Method of stacking pallets (2) in a stacker (1 ) according to any one of the claims 1 to 6, characterized in that the stacking at least comprises the following steps: • at least one pallet (2) is moved into a correct position in the stacker (1 ),

• the lifting frame (9) is driven to a disengaging position where at least one pre-loaded pallet (2) in the stacker is resting on the at least one pallet (2) to form a stack of pallets,

• the gripper plates (25) are moved into a disengaging position,

• the lifting frame (9) is further driven to a bottom position,

• the gripper plates (25) are further moved into an engaging position with a lower pallet of the stack,

• the lifting frame (9) is driven to a top position.

8. Method of stacking pallets (2) according to claim 7, characterized in that the stacker is pre-loaded by:

• at least one further pallet (2) is moved into a correct position in the stacker

(1 ),

• the lifting frame (9) is driven to the bottom position,

• the gripper plates (25) are moved into an engaging position with the at least one further pallet (2),

• the lifting frame (9) is driven to the top position.

8. Method of downstacking pallets (2) in a stacker (1 ) according to any one of the claims 1 to 6, characterized in that the downstacking at least comprises the following steps:

• lifting frame (9) is driven to a bottom position,

• gripper plates (25) are moved out of an engaging position with a lowest pallet (2) of the stack of pallets (2) and into a disengaging position,

• lifting frame (9) is driven to an engaging position relative to another pallet (2) of the stack, e.g. a second lowest pallet (2),

• gripper plates (25) are moved into the engaging position with the another pallet (2),

• lifting frame (9) is driven to a top position, removing at least the lowest pallet (2) from the stacker (1 ).

9. Method of placing a stack of pallets (2) in a stacker (1 ) according to any one of the claims 1 to 6, characterized in that the placing of a stack at least comprises the following steps:

• an operator puts the stack (3) correctly in the stacker (1 ) on the substrate,

• lifting frame (9) is driven to a bottom position,

• gripper plates (25) are moved into an engaging position with a lower pallet (2) of the stack (3),

• lifting frame (9) is driven to a top position.

10. Method of removing a stack of pallets (2) in a stacker (1 ) according to any one of the claims 1 to 6, characterized in that the removal of a stack at least comprises the following steps:

• lifting frame (9) is driven to a bottom position,

• gripper plates (25) are moved out of an engaging position with a lower pallet (2) of the stack (3) and into a disengaging position,

• lifting frame (9) is driven to a top position.

• an operator removes the stack (3) from the substrate.

11. A computer program product comprising instructions to cause the stacker of claims 1 to 6 to execute the steps of the method according to any of claims 7 to 10.

12. Use of a stacker (1 ) according to any one of claims 1 to 6 for square or rectangular sized pallets (2).