GB2330348A - Work positioning apparatus - Google Patents

Work positioning apparatus Download PDF

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Publication number
GB2330348A
GB2330348A GB9811616A GB9811616A GB2330348A GB 2330348 A GB2330348 A GB 2330348A GB 9811616 A GB9811616 A GB 9811616A GB 9811616 A GB9811616 A GB 9811616A GB 2330348 A GB2330348 A GB 2330348A
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United Kingdom
Prior art keywords
load
platform
sensing
control
load platform
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9811616A
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GB9811616D0 (en
Inventor
Anthony Douglas Harding
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ADVANCED HANDLING Ltd
Original Assignee
ADVANCED HANDLING Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GBGB9721827.5A priority Critical patent/GB9721827D0/en
Priority to GBGB9725994.9A priority patent/GB9725994D0/en
Application filed by ADVANCED HANDLING Ltd filed Critical ADVANCED HANDLING Ltd
Publication of GB9811616D0 publication Critical patent/GB9811616D0/en
Publication of GB2330348A publication Critical patent/GB2330348A/en
Withdrawn legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B66HOISTING; LIFTING; HAULING
    • B66FHOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F7/00Lifting frames, e.g. for lifting vehicles; Platform lifts
    • B66F7/06Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement
    • B66F7/065Scissor linkages, i.e. X-configuration
    • B66F7/0666Multiple scissor linkages vertically arranged
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B66HOISTING; LIFTING; HAULING
    • B66FHOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F7/00Lifting frames, e.g. for lifting vehicles; Platform lifts
    • B66F7/06Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement
    • B66F7/0625Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement with wheels for moving around the floor
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B66HOISTING; LIFTING; HAULING
    • B66FHOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F7/00Lifting frames, e.g. for lifting vehicles; Platform lifts
    • B66F7/06Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement
    • B66F7/08Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement hydraulically or pneumatically operated
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B66HOISTING; LIFTING; HAULING
    • B66FHOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075Constructional features or details
    • B66F9/20Means for actuating or controlling masts, platforms, or forks
    • B66F9/22Hydraulic devices or systems

Abstract

A work positioning apparatus comprises a load platform 22 which is moveable between an upper and lower position and furthermore moves in response to the load placed upon it. The platform is moved by means such as a hydraulic cylinder 12 provided with a reciprocable piston 14, connected via hydraulic line 16 to a pump motor 18. The piston 14 pushes on a chain wheel 20 which raises the platform via chain 24. A load sensing means, eg a load cell 26 or ultra -sonic detector (42, figure 3), detects the load on the platform and sends a signal to control apparatus. The position of the platform is measured by monitoring the angular position of the chain wheel 20 via a potentiometer and sending the signal to the control apparatus. The signals from load sensor and position sensor are connected to a comparator circuit and compared to reference signals. This allows the control circuit to send a raise or lower signal to pump motor 18 to raise or lower the platform 22 to keep the loading or unloading surface at a constant height. The piston and chain arrangement may be replaced by a mast and fork structure (figures 3 and 4) or by a scissor table provided with a piston (figures 2, 5, 6) in which the platform position is determined by monitoring the angular rotation of a pivot pin (34, figure 2). In "loading-mode" an audible alarm may be provided which indicates that the platform is about to move in response to the detection beam being interrupted. This follows a time delay which allows for unintentional interruption of the beam. The apparatus may be mobile (figures 1, 3-6) and may further be provided with a manual control system to over-ride the automatic system. The specification also discloses apparatus which is incrementally tiltable in response to the load placed upon the platform comprising control means load and position sensors and a progressively tiltable load platform.

Description

WORK POSITIONING APPARATUS AND METHOD The present invention relates to work positioning apparatus, and an associated method of work positioning. More particularly, the- invention relates to apparatus capable of raising or lowering, or tilting a variable load. The invention has applications, for example, in the raising or lowering of a pallet to a convenient height for the loading and unloading of goods thereon by operators, or the progressive tilting of a container as its contents are loaded or unloaded.
The invention may also have applications in assembly lines, in which the presence of a load is sensed and the height of a work station is adjusted accordingly.
Typically in the manufacturing industry including, for example, food processing plants and vegetable canning plants, mass produced goods flow off production lines. It is customary to stack the goods onto wooden pallets. The loaded pallets may then be moved onwards for transport or storage using a pallet truck or a forklift truck.
At present in many factories, operators wait at the end of production lines and are required to stack heavy loads onto the pallet. Conventional pallets comprise two horizontal platforms, with spacers between, providing a open space in which the forks of a forklift or pallet truck can be inserted.
Typically, the top surface of the pallet is only about 15cm above the floor height. As the first layer of goods stacked upon the pallet requires loading at floor level, the stacking and unstacking of the goods requires a significant amount of bending. This repeated bending, often lifting heavy articles, is tiring for the operators, who are prone to injury problems.
It is estimated that there are at least 110,000 manual handling injuries at work per year in the UK alone. This costs the UK between 110 and 130 million annually. In many countries, legal limits have been set for such operators regarding the maximum loads which may be lifted repeatedly.
This problem has been addressed to some extent by the use of scissor tables and stackers. Conventional stackers and scissor tables use hydraulic cylinders to power the raising/lowering mechanism. In the case of a scissor table, the cylinders work on the scissor arms or, in the case of a stacker, the cylinder pushes on the chain wheel to incrementally raise or lower the loading platform.
In these arrangements, the height of a loading platform, on which the pallet is mounted, is raised initially to the required loading height. As the pallet is loaded, the operator can lower the load platform manually, either by pulling a lever, or by pushing a button. In this way the loading height for the operator remains constant, and bending is reduced.
One drawback with this type of system is that adjustment of the load height is a manual operation, and the operator must break off from loading the pallet in order to lower the height of the load platform.
An automatic self-levelling system has been produced in which the load platform is mounted on an arrangement of springs, or a similar resilient arrangement. The mounting is calibrated to move the load platform incrementally from an initial loading height to a desired off-loading height, for a given maximum load.
One of the problems with this apparatus is that although the lowering of the load platform is responsive to the weight of the load, a different spring arrangement must be used for each type of load in order that the pallet is in its fully lowered positioned when the pallet is fully loaded, and thus to provide the operator with a constant working height. In view of this, the same arrangement cannot readily be used for tasks requiring a wide variation in the nature and maximum weight of the load. The installation of a different spring arrangement is a time consuming operation, and requires the apparatus to be out of action whilst the modifications are made.
Furthermore, because the loading platform is resiliently mounted, the apparatus can not be used to subsequently transport and unload the goods. As pallets are unloaded, the height of the load platform rises incrementally as the load is reduced. Thus the assistance of a stacker or fork lift is required to transport and unload the loaded pallets.
Additionally, the height control mechanism including the spring arrangement is located beneath the load platform. This has the effect that the lowest off-loading height position is limited by the bulk of the height control mechanism. As the load platform cannot be lowered to ground level, a fork lift truck, or similar apparatus must be employed to transport the loaded pallet. A fork lift truck is a relatively expensive item, and must be operated by a trained operator. Therefore the total cost of operating this self-levelling system is significantly greater than the more basic systems described above.
A need therefore exists for a constant rate lowering, or lifting, system which may be readily adapted for varying types of loads; and/or for a system which provides a self-levelling load height; and/or for such a system in which the off-load height may be varied; and/or apparatus in which the height and/or orientation of a load platform is automatically adjusted according to the load thereon.
It is an object of the present invention to provide improvements in relation to one or more problems discussed herein; and/or to provide improvements generally.
In one aspect of the invention there is provided work positioning apparatus which is capable of automatically lowering a load platform to the required height for loading, and which is also capable of raising a load platform to the required height for unloading In an embodiment the apparatus comprises a load platform being vertically moveable between a specified maximum height and a specified minimum height. There is also provided control apparatus for the lifting apparatus, wherein the control apparatus enables the platform to be incrementally lowered, or raised, automatically between an initial position and a pre-determined off-loading position, the pre-determined position being reached once the platform is fully loaded, or unloaded; the movement of the platform being responsive to a variation in load on the platform.
In this way, apparatus is provided which can maintain the top of a changing load, located on the load platform, at a convenient pre-determined height. This can be used to provide a constant working height for an operator, irrespective of the weight of the load to be lowered, or raised.
In an embodiment, the automatic system can be over-ridden, and once the pre-determined off load position has been reached the local platform may be lowered to the floor, using the override control.
In a further aspect of the invention there is provided lifting apparatus in which the off-load height of a pallet on the load platform is flush, or substantially flush, with the ground level. In this way, a loaded pallet may be transported with a hand pallet truck rather than requiring a fork lift truck, with the attendant cost implications, which is required if the off-load height of the pallet is substantially above ground level.
According to an embodiment of the present invention there is provided lifting apparatus comprising a load platform being vertically moveable between a specified maximum height and a specified minimum height; actuator means for moving the load platform; sensing means to detect a variation in the load on the load platform; and control means to control movement of the load platform by the actuator means to keep the working height constant as the load on the load platform is increased or decreased.
In an embodiment the sensing means includes position sensing means to detect the position of the load platform between its maximum and minimum heights. By detecting the position of the load platform and its current load, and comparing these with pre-set values of maximum height, minimum height, and total load, it is possible for the control means to calculate the desired position of the load platform, and to generate a signal to the actuator means to cause an automatic incremental lowering (or raising) of the platform. This embodiment of the invention thus provides a linear travel of the platform proportional to the increase in load.
In a simple case, if the total load is to be 1000kg, and 500kg has already been loaded, then the load platform would be located half way between its specified maximum and minimum heights. If an additional load of 250kg is added, the sensing means will provide a signal to the control means corresponding to a load value of 750kg. The control means will then generate a signal to the actuator means to lower the load platform until the position sensing means provides a signal corresponding to the load platform being at a position three quarters of the way between the maximum and minimum heights.
The invention thus provides self-adjusting lifting apparatus which may be readily adapted for varying types of loads. For different types of loads, the pre-set values of maximum load and/or maximum and minimum heights of the platform may be entered into the control system before loading or unloading commences. For the example given above, if a new maximum load value of 100kg is entered, then the control means will control the actuator means to move the load platform a tenth of the way between the maximum and minimum height for each 10kg added to the platform.
The maximum and minimum heights of the platform may be adjusted to take into account different loads or different sizes.
In an embodiment, the sensing means comprises load sensing means such as one or more load cells adapted to transmit a signal to the control means related to the load on the platform. The load cell may detect a change in the compression or tension in the transmission or support system for the load platform.
Alternatively, the load on the platform may be determined from a pressure transducer in the hydraulic or pneumatic system of the actuator means. As the load on the load platform is increased, the hydraulic or pneumatic pressure in the system will likewise increases by an amount proportional to the increased load.
In a further embodiment, the load on the platform is detected by measuring the linear movement of a resilient area and converting this to a signal to the control means. The resilient means may comprise one or more springs in compression or tension, a rubber assembly in compression or tension, or by providing one or more "bungee" cords acting in tension.
In an embodiment the position of the load platform is detected by monitoring the linear movement of the carriage or ram comprising the actuator means, and converting this linear movement to a signal to the control means.
Alternatively, if a chain hoist, or the like, is provided to raise and lower the platform, the position sensing means may comprise a rotary position transducer, e.g the angular movement of a transmission wheel being applied to a potentiometer. In this way movement of the platform between its maximum and minimum heights would correspond to angular movement between a maximum and minimum angular position.
Similarly, in a scissor table arrangement, the position sensing means may comprise sensing the angular rotation of the pivot pin connecting the scissor arms as the load platform is raised or lowered.
In an embodiment of the invention, the control means is set to raise or lower the load platform in response to any increase or decrease of load. In an alternative embodiment, the no change in position of the platform is effected until the increase in load on the platform reaches a pre-determined amount; and/or the presence of an object is detected in a predetermined trigger position.
In an alternative embodiment, the sensing means for detecting a variation in the load on the platform comprises an object sensing means, such as an ultra sonic detector, which detects the presence or absence of an object in the vicinity of the detector, corresponding to an addition or removal of a load from the platform.
If the work positioning apparatus is used for loading a pallet, the ultra sonic detector will be set to monitor the presence of an object on the load platform and send a signal to the control system to lower the platform, until it can no longer sense the presence of an object within a given range.
If the work positioning apparatus is to be used for unloading a pallet, the ultra sonic detector may be set to detect removal of an object from the platform, and to then send a control signal to the control system to raise the height of the load platform, until the presence of an object is once again detected.
The object sensing means is preferably movably mounted, for example slidingly mounted, in the vicinity of the load platform. It is envisaged that the position and height of the position sensing means would be adjusted to correspond to the optimum working height for each particular user.
The object sensing means may be mounted onto the structure of the apparatus itself. Preferably it may be mounted on either side of the apparatus to allow loading or unloading to take place from either side. Alternatively, the detector may be mounted on a free standing mast, which would be readily movably from one side of the apparatus to the other.
The range of the ultra sonic detector may be varied, according to the nature of the load. For example, if each layer to be located on the pallet comprises more than one object, the range may be adjusted such that the load platform is not lowered until the final object in the layer is located in a "trigger position", corresponding to a completed layer.
Additionally or alternatively, the angle of the ultra sonic detection beam may be adjusted to take account of the size of the load in relation to the size of the load platform.
The control means may be adapted to introduce an adjustable time delay between the detection of a variation by the object sensing means and the raising or lowering of the platform. An audible and/or visual alarm may also be activated prior to any movement of the load platfrom. The introduction of a time delay may be used to prevent the load platfrom from moving if an object is only momentarily sensed by the detector.
The output of the ultra sonic detector may be connected to a programme logic controller (PLC) comprising part of the control means.
In yet a further embodiment, the object sensing means may be provided by a series of light beams and photoelectric cells, the actuator means being disabled when a light beam is interrupted eg by. the top of a box.
In another aspect of the invention there is providing work positioning apparatus which is capable of automatically tilting a load platform as the load on the load platform varies.
Tilting apparatus is available, which allows a container to be tilted to allow better access as the container is loaded or unloaded. For example, if a box with relatively high side walls is to be loaded with small articles, the operator must bend and stretch to fill the bottom layers, whilst less stretching is required as the container is filled. However if the container is located on a tiltable load platform, the box can be initially tilted towards the operator, and the angle of tilt decreased as the container is loaded. Similarly, if a container is to be unloaded, the operator can readily access the top layers if the container is orientated with the bottom of the container parallel with the floor. However as the lower layers are reached, access is improved by tilting the container towards the operator.
It has been found that the positioning of the container at a convenient angle prevents back injury, and improves productivity. However with currently available apparatus, variation of the working attitude of the container on the load platform is controlled by the operator manually, or with a foot operated pedal. The operator must break off from the work in hand each time the tilt of the container is to be varied.
In an embodiment the apparatus of the present invention comprises a load platform being tiltable, for example about a generally horizontal axis, such that the load platform is moveable between a work attitude for a full load and a work attitude for an empty load. There is also provided control apparatus for the work positioning apparatus, wherein the control apparatus enables the platform to be incrementally tilted between the two positions as the load on the load platform varies between a maximum and minimum load.
In an embodiment there is provided work positioning apparatus comprising a load platform being moveable between an initial work attitude and a secondary work attitude; actuator means for moving the load platform; load sensing means to detect the load on the load platform; position sensing means to detect the position of the load platform between its initial and secondary attitudes; and control means to control movement of the load platform by the actuator means to progressively tilt the load platform between the two attitudes as the load on the load platform is varied.
Embodiments of the present invention will now be described by way of example only with reference to the following illustrative drawings in which: Figure 1 is a diagrammatic view of lifting apparatus according to an embodiment of the present invention, comprising a stacker; Figure 2 is a diagrammatic view of lifting apparatus according the embodiment, comprising a scissor table; Figures 3 and 4 are diagrammatic views of a stacker according to a further embodiment of the invention; and Figures 5 and 6 are diagrammatic views of a scissor table according to the further embodiment.
As can be seen in Figure 1, the lifting mechanism of a wheeled stacker 10 according to an embodiment of the present invention comprises at least one hydraulic cylinder 12, including a reciprocable piston 14, which is connected by a hydraulic line 16 to provide an oil connection to a pump motor 18. The pump motor 18 may be provided with a solenoid valve control to prevent over-run and provide for accurate positioning.
The piston 14 pushes on a chain wheel 20 to raise or lower a load platform, in the form of the stacker forks 22, using a chain hoist in the conventional manner. The piston 14 of the cylinder 12 carries the chain wheel 20 over which a chain 24, attached to load platform passes.
Load sensing means in the form of a load cell 26 mounted on the fixed end of the chain 24 detects the current load on the load platform 22 and converts this to an electronic signal which is sent to the apparatus control system (not shown).
The position of the load platform 22 between its maximum and minimum heights is detected by monitoring the angular position of the chain wheel 20 and applying this to a potentiometer mounted thereon. The potentiometer output signal is also sent to the apparatus control system. Movement of the load platform 22 between its maximum and minimum heights typically corresponds to an angular rotation of the chain wheel through 3200.
The outputs of the load sensor and the position sensor are connected to a comparator circuit, such as a Wheatstone bridge arrangement, forming part of the apparatus control system.
These signals are compared to reference values, which comprise a fixed bias for the particular apparatus, and a setting which may be varied by the operator according to the particular nature of the total load to be loaded or un-loaded.
Using a comparison between the detected position and the detected load signals with the pre-set settings, it is possible to adjust a comparison window for incremental signals to the hydraulic system. This will allow for either a "raise" or "lower" signal being sent to the pump motor 18 so as to cause movement of piston 14, and to raise or lower the work platform 22.
The apparatus also includes a manual control system which allows for the overriding of the automatic mode for safety and operator use. The over-ride also allows the load-dependent system to be by-passed, to allow a pallet on the load platform to be deposited on the floor, for example.
In use, the operator considers the nature of the load, for example total load, initial and final platform heights etc, and adjusts the system controller settings accordingly. The operator uses the manual control, if necessary, to set the height of the platform 22 to the required height. For the loading of goods on to the pallet, the platform will be a raised position, and if the apparatus is to be used to unload a pallet, then the platform would be lowered to the desired position.
For a loading operation, an empty pallet is placed on the load platform. As the load on the load platform is increased, the signal sent by the load cell 26 to the control system changes.
A signal relating to the position of the load platform 22 between its maximum and minimum height settings is provided by the potentiometer mounted on the chain wheel 20. The controller compares the signal from the load sensor to the reference settings, and operates the pump motor to move the piston 14 and lower the platform 22, until the potentiometer provides a signal corresponding to the correct position for the increased load. A constant working height for the operator has thus been maintained.
This process is repeated with each increase of load on the load platform, until the total load has been loaded onto the pallet and the pallet has reached the desired off-loading height.
In one variation, the load-dependent system provides an offloading height just above floor level, to enable the stacker to be moved to a different location. The manual over-ride can then be used to lower the pallet to the floor.
In an alternative embodiment of the invention shown in Figure 2, the apparatus comprises a scissor table 28. The operation is similar to that described above except that piston 14 works on the scissor arm arrangement 30 to incrementally raise or lower the load platform 32. In this embodiment, the position sensing is achieved by sensing the angular rotation of the pivot pin 34, connecting the scissor arms, as the load platform is raised or lowered, and applying this to a potentiometer, as before.
The load on the load platform 32 is monitored by sensing pressure variation in the hydraulic line 16 using a pressure transducer.
In apparatus of the present invention, the load platform remains stationary at the desired off-loading height allowing for ready unloading. In contrast, in prior art spring-loaded platforms, the platform rises as the load is removed, and an additional stacker or fork lift truck is required to remove the pallet.
In both of the described embodiments the role of the apparatus can be reversed and used for off-loading purposes i.e. a fully loaded pallet can be placed on the load platform. As the load is removed, the load platform rises, and a constant working height may be maintained.
A variation of manual raising of the load platform and automatic lowering is also contemplated for a load only version is also contemplated.
In an alternative embodiment of the invention illustrated in Figures 3 and 4. A stacker 40, similar to that described in relation to Figure 1 is provided, having a load platform in the form of stacker forks 22. The load platform 22 is illustrated in Figure 3 at its maximum height position, and the minimum height position is depicted in dotted lines.
The load cell and position sensor of the embodiment of Figure 1 is replaced by an ultra sonic detector 42, which provides the sensing means for detecting a variation in the load on the platform.
The ultra sonic detector 42 is located on a mast member 44 provided as part of the structure of the stacker, and the detector 42 is vertically positionable on the mast 44 between a maximum height (illustrated in Figure 3 by dotted lines) and a minimum height, shown in Figure 3. A similar mast structure is provided on both sides of the stacker, so that the operator of the stacker may decide which side of the apparatus the detector should be mounted. This enables loading or unloading to take place from either side.
On activation of the detector 42, a relay output is provided to control either a solenoid valve to release fluid causing a lowering of the platform 22, or to activate a motor start solenoid to allow raising of the load platform 22, depending on whether the control system is set to load or unload mode.
A bottom limit safety switch 46 is provided to prevent lowering of the platform below the minimum height position, and a top limit safety switch is also provided (not shown).
A manual control over-ride 48 is provided to enable the load platform to be raised or lowered independently of the ultra sonic detector. In addition, the manual control allows the apparatus to be operated when the upper or lower limit switches are activated.
In use, the operator of the stacker sets the height of the detector 42 to correspond to a convenient working height for the load platform 22.
If the work positioning apparatus is used for loading a pallet, the ultra sonic detector 42 will be set to monitor the presence of an object on the load platform 22 and send a signal to the control system to lower the platform, until it can no longer sense the presence of an object within a given range. If the work positioning apparatus is to be used for unloading a pallet, the ultra sonic detector may be set to detect removal of an object from the platform, and to then send a control signal to the control system to raise the height of the load platform, until the presence of an object is once again detected.
The range of the ultra sonic detector 42 may be varied, according to the nature of the load. For example, if each layer to be located on the pallet comprises more than one object, the range may be adjusted such that the load platform is not lowered until the final object in the layer is located in a "trigger position", corresponding to a completed layer.
Typically, the range of the detector 42 will be adjustable from about 0.25 metres to 3 metres.
The angle of the ultra sonic detection beam is adjusted to take account of the size of the load in relation to the size of the load platform.
If the apparatus is set to loading mode, and a box is placed onto the load platform, the ultra sonic detection beam is interrupted by the box, and a signal is sent to the control system. The control system introduces a time delay of a few seconds. If the detection beam still indicates that a object is present of the load platform, an audible alarm will sound, and the actuation means lowers the platform until the detection beam is no longer interrupted. This results in the top of the last loaded item being located at the height of the ultra sonic detector, which in turn corresponds to the chosen working height of the operator. The time delay ensures that the work platform is not moved in response to an unintentional interruption in the detection beam, for example by a stray object, and the audible warning indicates to the operator that the platform is about to move.
Figures 5 and 6 illustrate this embodiment of the invention used in conjunction with a scissor table 50, similar to that described in Figure 2. However the position sensing means and the load sensing means described in relation to that embodiment have been replaced by a ultra sonic detector 52.
In this embodiment, the detector 52 is mounted on a free standing mast 54, which is readily movably from one side of the apparatus 50 to the other. The detector 52 is vertically positionable on the mast 54 between a maximum height, illustrated in Figure 5, and a minimum height (shown in Figure 5 in dotted lines). Operation of the apparatus is similar to that of the embodiment of Figures 3 and 4.

Claims (19)

  1. CLAIMS 1 Lifting apparatus comprising a load platform which is moveable between a specified maximum height and a specified minimum height; cpntrol apparatus to control movement of the load platform between an initial position and a pre-determined off-loading position, the pre-determined position being reached once the platform is fully loaded, or unloaded; whereby the movement of the platform is responsive to a variation in load on the platform.
  2. 2 Apparatus according to claim 1 further comprising actuator means for moving the load platform; and sensing means to detect a variation in the load on the load platform; whereby the control means to controls movement of the load platform by the actuator means to keep the working height constant as the load on the load platform is increased or decreased.
  3. 3 Apparatus according to claim 1 or claim 2 wherein the sensing means includes position sensing means to detect the position of the load platform between its maximum and minimum heights.
  4. 4 Apparatus according to claim 3 wherein the position of the load platform is detected by monitoring the linear movement of the carriage or ram comprising the actuator means, and converting this linear movement to a signal to the control means.
  5. 5 Apparatus according to claim 3 wherein the position sensing means comprises a rotary position transducer.
  6. 6 Apparatus according to claim 3 wherein the position sensing means comprises sensing the angular rotation of a pivot pin connecting the scissor arms as the load platform is raised or lowered.
  7. 7 Apparatus according to any one of the preceding claims wherein the sensing means comprises load sensing means adapted to transmit a signal to the control means related to the load on the platform.
  8. 8 Apparatus according to claim 7 wherein the load on the platform is determined from a pressure transducer in the hydraulic or pneumatic system of the actuator means.
  9. 9 Apparatus according to claim 7 wherein the load on the platform is detected by measuring the linear movement of a resilient area and converting this to a signal to the control means.
  10. 10 Apparatus according to any one of the preceding claims wherein no change in position of the platform is effected until the increase in load on the platform reaches a predetermined amount.
  11. 11 Apparatus according to any one of the preceding claims wherein no change of position of the platform is effected until the presence of an object is detected in a predetermined trigger position.
  12. 12 Apparatus according to any one of the preceding claims wherein the sensing means for detecting a variation in the load on the platform comprises an object sensing means which detects the presence or absence of an object in the vicinity of the detector, corresponding to an addition or removal of a load from the platform.
  13. 13 Apparatus according to claim 12 wherein the object sensing means comprises an ultra-sonic detector.
  14. 14 Apparatus according to claim 13 wherein the angle of the ultra-sonic detection beam is adjustable to take account of the size of the load in relation to the size of the load platform.
  15. 15 Apparatus according to any one of claims 12 to 14 wherein the object sensing means is movably mounted, for example slidingly mounted, in the vicinity of the load platform.
  16. 16 Apparatus according to any one of the preceding claims wherein the control means is adapted to introduce an adjustable time delay between the detection of a variation by the object sensing means and the raising or lowering of the platform.
  17. 17 Apparatus comprising a load platform being tiltable, for example about a generally horizontal axis, such that the load platform is moveable between a work attitude for a full load and a work attitude for an empty load; and control apparatus to control movement of the platform to be incrementally tilted between the two positions as the load on the load platform varies between a maximum and minimum load.
  18. 18 Work positioning apparatus comprising a load platform being moveable between an initial work attitude and a secondary work attitude; actuator means for moving the load platform; load sensing means to detect the load on the load platform; position sensing means to detect the position of the load platform between its initial and secondary attitudes; and control means to control movement of the load platform by the actuator means to progressively tilt the load platform between the two attitudes as the load on the load platform is varied.
  19. 19 Apparatus substantially as herein described with reference to the accompanying drawings.
GB9811616A 1997-10-16 1998-06-01 Work positioning apparatus Withdrawn GB2330348A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GBGB9721827.5A GB9721827D0 (en) 1997-10-16 1997-10-16 Work positioning apparatus and method
GBGB9725994.9A GB9725994D0 (en) 1997-12-09 1997-12-09 Work positioning apparatus and method

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GB9811616D0 GB9811616D0 (en) 1998-07-29
GB2330348A true GB2330348A (en) 1999-04-21

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100364877C (en) * 2003-11-12 2008-01-30 烟台奔腾汽车检测维修设备制造有限公司 Intelligent electric controlling device and controlling method for double pole lifter
CN102009340A (en) * 2010-09-07 2011-04-13 成都立航科技有限公司 Aircraft engine mounting vehicle
CN103288010A (en) * 2013-05-30 2013-09-11 安徽德摩新能源叉车股份有限公司 Forklift structure
CN103523710A (en) * 2013-10-18 2014-01-22 朱红蔚 Loading and unloading robot with complete-machine automatic lifting and container-entering operation functions
DE102012101500A9 (en) * 2012-02-24 2014-03-13 Dr. Schniz GmbH Method and arrangement for detecting conditions of a vehicle descriptive data and a corresponding computer program and a corresponding computer-readable storage medium
CN106241389A (en) * 2016-08-26 2016-12-21 杭州市粮食收储有限公司良渚分公司 Multi-functional stacker
CN108706523A (en) * 2018-06-13 2018-10-26 芜湖金智王机械设备有限公司 Fork truck
CN110980574A (en) * 2019-12-12 2020-04-10 福建龙翔水产食品有限公司 Aquatic product freezing is with putting on shelf device
CN112554627A (en) * 2021-01-14 2021-03-26 上海森享汽车用品有限公司 Underground garage vehicle waterlogging prevention equipment

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102602851B (en) * 2012-03-27 2014-07-02 中国人民解放军总后勤部建筑工程研究所 Portable cross-country hand fork lifter
CN111747125A (en) * 2020-07-10 2020-10-09 常德仁和盛五金包装制品有限公司 Folding pile up neatly structure of cloth

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB899422A (en) * 1957-05-01 1962-06-20 Allan Bracewell Hydraulics Ltd Improvements in or relating to hydraulically operated lifting apparatus
US3967737A (en) * 1974-08-19 1976-07-06 Conveyor Systems, Inc. Depalletizing and pallet stacking apparatus
US4082194A (en) * 1976-06-30 1978-04-04 Sheehan Russell T Self-contained pallet-elevating bag palletizer
US4106635A (en) * 1977-02-17 1978-08-15 Yasui Sangyo Co., Ltd. Elevatable depalletizing system
GB1569171A (en) * 1975-10-31 1980-06-11 Toyo Seikan Kaisha Ltd Apparatus for stacking trays
US4229650A (en) * 1977-12-14 1980-10-21 Canon Kabushiki Kaisha Position and presence detecting device for stacked sheet members
US5518230A (en) * 1994-10-31 1996-05-21 Xerox Corporation Stack height sensing machanism

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB899422A (en) * 1957-05-01 1962-06-20 Allan Bracewell Hydraulics Ltd Improvements in or relating to hydraulically operated lifting apparatus
US3967737A (en) * 1974-08-19 1976-07-06 Conveyor Systems, Inc. Depalletizing and pallet stacking apparatus
GB1569171A (en) * 1975-10-31 1980-06-11 Toyo Seikan Kaisha Ltd Apparatus for stacking trays
US4082194A (en) * 1976-06-30 1978-04-04 Sheehan Russell T Self-contained pallet-elevating bag palletizer
US4106635A (en) * 1977-02-17 1978-08-15 Yasui Sangyo Co., Ltd. Elevatable depalletizing system
US4229650A (en) * 1977-12-14 1980-10-21 Canon Kabushiki Kaisha Position and presence detecting device for stacked sheet members
US5518230A (en) * 1994-10-31 1996-05-21 Xerox Corporation Stack height sensing machanism

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100364877C (en) * 2003-11-12 2008-01-30 烟台奔腾汽车检测维修设备制造有限公司 Intelligent electric controlling device and controlling method for double pole lifter
CN102009340A (en) * 2010-09-07 2011-04-13 成都立航科技有限公司 Aircraft engine mounting vehicle
CN102009340B (en) * 2010-09-07 2012-08-29 成都立航科技有限公司 Aircraft engine mounting vehicle
DE102012101500A9 (en) * 2012-02-24 2014-03-13 Dr. Schniz GmbH Method and arrangement for detecting conditions of a vehicle descriptive data and a corresponding computer program and a corresponding computer-readable storage medium
CN103288010A (en) * 2013-05-30 2013-09-11 安徽德摩新能源叉车股份有限公司 Forklift structure
CN103288010B (en) * 2013-05-30 2016-06-15 安徽德摩新能源叉车股份有限公司 A kind of fork lift truck structure
CN103523710A (en) * 2013-10-18 2014-01-22 朱红蔚 Loading and unloading robot with complete-machine automatic lifting and container-entering operation functions
CN103523710B (en) * 2013-10-18 2016-04-27 朱红蔚 There is the handling robot of complete machine from lifting and inlet operating function
CN106241389A (en) * 2016-08-26 2016-12-21 杭州市粮食收储有限公司良渚分公司 Multi-functional stacker
CN106241389B (en) * 2016-08-26 2018-09-28 杭州市粮食收储有限公司良渚分公司 Multi-functional stacker
CN108706523A (en) * 2018-06-13 2018-10-26 芜湖金智王机械设备有限公司 Fork truck
CN110980574A (en) * 2019-12-12 2020-04-10 福建龙翔水产食品有限公司 Aquatic product freezing is with putting on shelf device
CN112554627A (en) * 2021-01-14 2021-03-26 上海森享汽车用品有限公司 Underground garage vehicle waterlogging prevention equipment

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