GB2536664A

GB2536664A - Two-sided fork lift apparatus

Info

Publication number: GB2536664A
Application number: GB1505013.1A
Authority: GB
Inventors: Mcvicar Martin; Moffett Robert; Whyte Mark
Original assignee: Combilift Ltd
Current assignee: Combilift Ltd
Priority date: 2015-03-25
Filing date: 2015-03-25
Publication date: 2016-09-28
Also published as: GB201505013D0

Abstract

A fork lift apparatus 10 has a fork structure mounted on a support frame 16, the fork structure comprising at least one arm 34, 36 for engaging with and lifting a load, which fork structure can be rotated about the pivot 34C in a generally vertical plane, between a first position wherein an arm 34A, 36A of the fork structure is directed generally horizontally in the direction of a first side of the support frame (24 fig. 3), and a second position wherein an arm 34B, 36B of the fork structure is directed generally horizontally in the direction of a second opposed side of the support frame (26 fig. 3). The arm of the fork structure may be rotatable through 180 degrees between the first and second positions (fig. 18) or first and second arms 34A, 34B may meet at the pivot point and define an internal angle between 70° and 110°. The fork structure may translate between a recessed position within a holding area within the support frame 16 (fig. 5) and an extended position (fig. 4). A short lift mechanism (70 fig. 17) may be provided to raise a load from a supporting surface. A separate hoist mechanism may raise the fork structure vertically along the frame 16. The apparatus may be used as part of a fork lift truck, fixed in position or traversable along a narrow aisle.

Description

Two-sided fork lift apparatus

Technical Field

This invention relates to fork lift apparatuses.

Background Art

For handling of loads in narrow aisles a variety of fork lift trucks are known which give improved manoeuvrability. Nevertheless conventional fork lift trucks require sufficient space to manoeuvre into and along an aisle, turning space to engage a load (such as a pallet stacked in a bay along the aisle) withdraw the pallet, and manoeuvre back along the aisle with the load in place. The most manoeuvrable of these fork lift trucks include mechanisms such turret heads and rotatable masts, whereby the fork carriage can be rotated, extended and retracted along perpendicular axes relative to the driving axis of the truck.

The construction of a turret head must be very strong as the load is a cantilever type. Also, as the width of the load increase then the turret must get longer in order to allow this wider load to rotate. This additional length in turn increases the load moment.

An alternative approach is to employ fixed infrastructure such as stacker cranes which typically traverse along an aisle, and have a carriage that can be raised, lowered and extended to pick up pallets. However, the construction of the warehouse for a stacker crane requires the installation of guides on the roof and floor of the warehouse to accommodate the crane, which results in higher costs.

This invention is directed at providing an alternative and improved mechanism for a fork lift apparatus.

Disclosure of the Invention

There is provided a fork lift apparatus comprising: a supporting frame for mounting a fork mechanism, the supporting frame in use defining a vertical direction, a first side and a second side; a fork structure mounted on the support frame, the fork structure comprising at least one arm for engaging with and lifting a load; a pivot provided on the fork structure, the pivot being arranged such that the fork structure can be rotated about the pivot in a generally vertical plane, between a first position wherein an arm of the fork structure is directed generally horizontally in the direction of the first side, and a second position wherein an arm of the fork structure is directed generally horizontally in the direction of the second side; and a fork lift mechanism for raising and lowering the fork structure.

The use of a pivot to rotate a fork structure within a vertical plane from a first position where an arm is directed to one side, to a second position where an arm is directed to an opposite side of a frame, provides a robust, inexpensive solution to the problem of providing a compact mechanism for operating with loads in narrow spaces such as aisles.

In one embodiment, the fork structure comprises a single arm rotatable through about 180 degrees between the first and second positions.

Thus, the arm can be flipped over from a first-side facing position to a second-side facing position.

Suitably, the fork structure will include or be mounted on a supporting structure which bears the weight of the arm and any load carried by the arm.

It is to be understood that this "single arm" solution will typically be implemented with a pair of such arms parallel to one another, i.e. two "single arm" fork structures alongside and spaced apart from each other, to give a pair of forks for engaging a load such as a pallet.

In a currently more preferred embodiment the fork structure comprises first and second arms which meet at a junction which defines an internal angle between the arms of from 70 to 110 degrees, said pivot being generally aligned with said junction.

In this embodiment, the fork structure can be rotated through an angle of 180 degrees minus the internal angle. Most typically the arms will be at about 90 degrees from one another and the structure will thus be rotated through 90 degrees.

An advantage of this arrangement to flipping a single arm through 180 degrees is that there are two arms, one horizontal to engage the load, and the other more or less upright. Where these arms are fixed in position relative to one another the structural support required to counteract the weight of the arms and the load they carry can be provided to the upright arm. In other words, instead of having to put a support under the single arm (which interferes with that arm being at ground level), one can provide a stop which prevents the more upright arm from over-rotating, and thus supports the fork structure and the carried load from above. This is further advantageous because the stop can be at or towards the free end of the more upright arm, providing mechanical advantage relative to a stop below the single arm solution, which will generally have to be located near the pivot to avoid interfering with the carried load.

Preferably, the fork lift apparatus further comprises a translation mechanism for translating the fork structure in the direction of either the first side or the second side.

Preferably, the translation mechanism is operable to translate the fork structure when in the first position between a recessed first position state wherein the fork structure is recessed within the supporting frame, and an extended first position state wherein an arm extends beyond the first side of the frame for engagement with a load.

Preferably, the translation mechanism is operable to translate the fork structure when in the second position between a recessed second position state wherein the fork structure is recessed within the supporting frame, and an extended second position state wherein an arm extends beyond the second side of the frame for engagement with a load.

Thus, the preferred embodiments both rotate the fork structure through a vertical plane, and translate the fork structure horizontally from a recessed position to an extended position.

Generally speaking, when the translation mechanism has the forks in a recessed state, and the forks are then rotated (from first position to second position, or vice versa) they will be in an extended state for that new rotated position.

Preferably, the frame defines a holding area.

Preferably, the holding area is dimensioned to accommodate the fork structure.

Preferably, the holding area accommodates the forks when retracted by the translation mechanism into a recessed state.

Preferably, the fork lift mechanism comprises a short-lift mechanism for displacing the fork structure vertically by a sufficient distance to raise a load from contact with a supporting surface.

Thus, the short-lift mechanism is suitable to lift a pallet from the ground or from the shelf or other surface on which it rests, allowing it to be moved laterally.

Further, preferably, the frame comprises a structural member at ground level and the short-lift mechanism is operable to displace the forks vertically by a sufficient distance to clear said structural member when the fork structure is translated relative to the frame.

The clearance distance may increase by a small amount (e.g. 5-20 cm) so that a load supported on the forks can also clear and be moved over the structural member. The structural member may be e.g. a cross-member extending from one side of the frame to another.

Preferably, the fork lift mechanism comprises a hoist mechanism for raising the fork structure vertically along the frame, the hoist mechanism being separate from a short-lift mechanism, if present.

Thus in a preferred embodiment there will be two distinct lifting mechanisms: a hoist for large scale vertical movements of the fork structure, and a short-lift mechanism which can move the fork structure sufficiently to allow lateral manoeuvring of the forks and the load they carry.

In preferred embodiments, a carriage or sub-frame carries the fork structure, with the rotational and translational mechanisms, if present, causing the fork structure to pivot, and to be horizontally translated, relative to the sub-frame. Preferably, then, the entire sub-frame and all of its supported components are moved by the hoist mechanism, while in contrast, the short-lift mechanism may move the fork structure vertically by relatively small distances relative to the sub-frame.

Suitably, the hoist mechanism may comprise a cylinder-and-piston arrangement, which is connected to the fork structure via a chain. However, the skilled person will appreciate that other hoist mechanisms may be employed such as hydraulic and electric winches or indeed any other hoisting arrangement known in the art and suitable for this application.

Suitably, the chain may traverse a system of pulleys to multiply the displacement of the driving mechanism.

Optionally, the frame of the fork lift apparatus may be telescopic allowing it to be retracted and extended in height.

Preferably, when two connected arms are provided in a fork structure, the fork arms are disposed with an internal angle of about 90 degrees or more.

Less than 90 degrees is less preferred as it means that the more upright arm may interfere with the load mounted on the horizontal arm. This may not be very problematic for angles of 70 degrees or more, though preferably the angle is 85 degrees or more. However, where the internal angle is more than 90 degrees this may be acceptable, as the only penalty of a greater angle is in terms of the dimensions of the fork structure (i.e. the more upright arm extends back behind the pivot, increasing the pivot length). For angles not much greater than 90 degrees, e.g. 90 to 110 degrees, the increased length may be acceptable.

Preferably the fork lift apparatus will have a pair of said fork structures disposed with pivots aligned coaxially, whereby when both fork structures are in the first position, both fork structures have an arm extending in parallel towards the first side, and both fork structures being coupled to said fork lift mechanism to be raised and lowered together.

Thus, rather than a single fork, a pair of forks can be provided.

Preferably, the pair of fork structures are rotationally coupled together such that when one is in the first position or second position, the other is similarly in that position.

Optionally, the apparatus comprises a plurality of said fork lift mechanisms, each fork lift mechanism acting independently and being coupled to a set of one or more fork structures, such that a plurality of sets of fork structures are disposed alongside one another in a single frame allowing for the independent handling of side-by-side loads.

A double-width or triple-width frame can be provided, with two or three independent hoists, and each hoist having its own set of forks which can project out the first side or second side independently of the other sets of forks coupled to the other hoist(s). Such an apparatus can handle several loads.

Preferably, the apparatus is provided in the form of a fork lift truck, and further comprises motive means allowing the frame to be moved and steered as a vehicle.

Alternatively the apparatus may be provided in the form of a crane which may be fixed in position or which may be traversed sideways along an aisle with the first and second sides facing the sides of the aisle.

Brief Description of the Drawings

Fig. 1 is a perspective view of a forklift apparatus; Fig. 2 is a side elevation of the forklift apparatus; Fig. 3 is an end elevation of the forklift apparatus; Figs. 4 and 5 are detailed perspective views of the fork structure of the forklift apparatus; Fig. 6 is an isolated side view of a fork of the fork structure; Fig. 7 is a top plan view of the forklift apparatus; Fig. 8 is a detailed view of the translational carriage of the forklift apparatus; Figs. 9 and 10 are perspective and side views respectively of the forklift apparatus engaging a pallet; Figs. 11 and 12 are perspective and side views respectively of the forklift apparatus lifting the pallet off the base on which it rested; Figs. 13 and 14 are perspective and side views respectively of the forklift apparatus retracting the pallet into a load handling area of the forklift apparatus; Fig. 15 is a perspective view of the forklift apparatus with the forks in a raised, retracted position; Fig. 16 is a perspective view of the forklift apparatus with the forks in a raised, extended position; Fig. 17 shows a detail of the view of Fig. 16; Fig. 18 is a perspective view of an alternative fork structure; and Fig. 19 shows a forklift apparatus in different positions and steering configurations as it manoeuvres within a warehouse.

Detailed Description of Preferred Embodiments

Fig. 1 shows a forklift apparatus, indicated generally at 10, taking the form of a forklift truck for operation in narrow warehouse aisles. The truck is designed to handle palletised loads, though it can handle other loads of suitable dimensions. The truck 10 has a base 12 with four wheels 14, all of which steer and at least one but preferably two or more of which are driven. Extending from the base 12 is a vertical supporting frame 16.

Referring additionally to Figs. 2 and 3 it can be seen that the vertical frame comprises first 18 and second 20 uprights, braced at the top by a crossbar 22. The frame defines (Fig. 3) a first side 24 and second side 26 of the truck. Additional structural support is provided in the base by a plurality of transverse struts 28 connecting a first base body section 30 to a second base body section 32.

A fork structure comprises a pair of forks 34,36 each of which (as will be described in further detail below) takes the form of an L-shaped member with two arms fixedly joined at a pivot point.

Figs. 4 and S show the fork structure more clearly, when raised along frame 16 away from the ground. Fig. 6 shows one of the forks 34 from the side.

Each fork 34,36 comprises a respective first arm 34A, 36A and second arm 34B, 36B disposed at 90 degrees to one another and meeting at a respective junction 34C, 36C, where the junctions are mounted along a common axis about which they rotate in synchronicity. Rotation is achieved by a hydraulically driven chain drive 38 (Fig. 5) which is mounted on a stop bar 40 and which engages a sprocket wheel 42 mounted on the rotation axis. As seen in Fig. 6, with reference to fork 34, the fork can be rotated about the pivot 34C in a generally vertical plane, between a first position wherein a first arm 34A of the fork structure is directed generally horizontally in the direction of the first side with the second arm 34B generally vertical, and a second position wherein the first arm 34A' is in a generally vertical position and the second arm 34B' is generally horizontal. As can be seen with reference to Figs. 4 and 5, when in either first or second position, whichever arm of a fork is vertical rests against the stop bar 40, and the stop bar 40 thereby prevents over-rotation, particularly when a heavy load is carried by the horizontal forks.

Figs. 4 and S also demonstrate that the horizontal forks can either be extended out from the truck or can be retracted within a load area of the truck defined between rails 44, 46, whose footprint is within the footprint of the truck's base 12.

Thus, if one compares Fig. 4 with Fig. 5, it can be seen that prior (Fig. 4) to the rotation of the fork structure, the first arms 34A, 36A extend out of the first side 24 and beyond the footprint of the base of the truck. The second arms 34B, 36B are vertical but within the footprint of the truck towards the first side of the truck's footprint.

As seen in Fig. 5, after rotation (and without any horizontal translation of the fork structure between the rails), the second arms 34B', 36B' are now horizontal and within the truck's footprint, and the first arms 34A', 36A' are vertical and at within the truck's footprint.

It can be seen by comparing Fig. land Fig. 4, the fork structure as a whole can be translated horizontally between the rails 44, 46. Thus in Fig. 1, the vertical second arms are towards the second side edge of the loading area, with the horizontal first arms between the rails 44, 46. In Fig. 4, the fork structure has been translated in the first side direction, so that the second arms are towards the other edge of the loading area and the first side arms are directed outwardly beyond the truck's footprint.

It will be understood that this allows for the forks to be extended (as in Fig. 4) to engage a load such as a pallet located on the first side 24 (Fig. 3) of the truck, then allows the forks to be retracted (as in Fig. 1 to bring the load within the load area between the rails and within the truck's footprint. In the case that a load is located on the second side 26 (Fig. 3) of the truck, and especially where the aisle is too narrow for the truck to be turned around, the forks can be rotated (as per Fig. 6) so that the second arms can be extended or retracted in the same manner to engage, pick up and retract a load into the load area from the second side.

Referring to Fig. 7 the truck can be seen from above and the translation mechanism is visible. In Fig. 7 one can see the crossbar 22 above the base 30, 32, with the aforementioned rails 44, 46 defining a loading area between them.

Referring also to Fig. 8, each rail 44, 46 is provided with an inwardly-facing toothed surface, which forms the rack 48 of a rack-and-pinion gear pair. The circular gear or pinion 50 for the right-most rail 46 is just visible in Fig. 8 below a motor 52 mounted on a translational carriage 54 (of which the stop bar 40 forms part) that carries the fork structure 34, 36. A corresponding motor 52 (not visible in Fig. 8) is provided on the other side of the carriage 54, driving a respective pinion gear along rail 44. In this way, the translational carriage 54 can be driven horizontally towards the first or second side, causing a respective fork arm to be extended or retracted, depending on the rotation state of the fork structure. The translational carriage moves relative to a larger sub-frame on which it is mounted, the sub-frame being defined by (Fig. 8) the rails 44, 46, a pair of side plates 56, an upper transverse member 58, and two lower transverse plates 60 (Fig. 4).

Fig. 9 shows the forklift truck 10 engaging a pallet 64. The same action is shown in the context of a narrow aisle in Fig. 10, with the pallet 64 bearing a load 66, and being held in a rack 63 where such loads are stacked. It will be appreciated that the truck in Fig. 10 has been manoeuvred to this position with the forks retracted as shown in Fig. 1, then the translational carriage has been driven to the first side to extend the forks into the pallet.

In Figs. 11 and 12, in similar views to Figs. 9 and 10, a short-lift mechanism (described below in relation to Fig. 17) has raised the fork structure upwards relative to the translational carriage, which lifts the pallet free of the supporting surface of the rack (or ground). In doing so, it also raises the underside of the pallet higher than the transverse struts 28 of the chassis (Fig. 1) and the transverse plates 60 of the sub-frame, allowing it to be retracted into the loading area within the footprint of the truck without colliding with these structures.

Figs. 13 and 14 show the truck after the translational carriage has been retracted towards the second side, and it will be observed that the pallet 64 and load 66 are now within the dimensions of the width of the body section 30. Thus, the truck is now free to drive along the aisle, despite the aisle being little wider than the truck itself.

Figs. 15 and 16 show the truck operating at a height. The sub-frame 44,46,56,58,60 (Fig. 16) has been elevated by the hoist mechanism to the top of the vertical supporting frame 16. In Fig. 15 the load is retracted, while in Fig. 16 it has been extended out the first side. The operations to engage a load or to place it on a rack are the same when working at a height as for the previously described operations at ground level.

In Fig. 17 the short-lift mechanism is shown. Two guide arms 68 extend vertically and form part of the translational carriage structure. A pair of hydraulic cylinders 70 act on the stop bar and thereby on the entirety of the fork structure, to raise and lower the fork structure relative to the translational carriage. Actuation of these cylinders (which are paired to simultaneously extension or retraction) thus effects to lift the fork structure a relatively short distance relative to the sub-frame, allowing a load to clear the interfering structures of the truck when being retracted.

Fig. 18 shows an alternative fork structure. The forks are a pair of parallel arms 82, 84 which rest on on a stop bar 86. The fork arms can be flipped through 180 degrees to point in the opposite direction and rest on a parallel stop bar 88 on the other side of the fork structure. A sprocket wheel 90 is mounted on an axle 92 and is driven by a chain drive which is powered by a pair of hydraulic cylinders 96. Actuation of the chain drive causes the axle to rotate the arms through 180 degrees so that they point towards a first side or a second side. It will be appreciated that this structure can be substituted for the structure shown in earlier figures with minimal modification to the rest of the truck.

Fig. 19 shows the steering of the truck as it moves between four positions, denoted as 10A, 10B, 10C and 10D. A warehouse environment 100 has a pair of aisles 102, 104 defined between shelving racks 106, 108, 110, 111. The truck 10 has a pair of front wheels 112 and a pair of rear wheels 114, though in actuality these are arbitrary names, as at least one "front" wheel and at least one "rear" wheel can be driven in either direction and all four wheels are steerable. In the illustrated embodiment, two diagonally opposite wheels, one front 112 and one rear 114, are driven, though any number of wheels could be driven, including all four wheels. In manoeuvring from position 10A to 10B, the two front wheels are steered and the rear wheels locked in straight-ahead position. Then at 1013, all four wheels are turned to a sideways orientation and the left-most front wheel and rear wheel steer as the truck drives to position 10C. From position 10C the wheels will again be rotated through 90 degrees so that they are pointing along the direction of the aisle 102, and as seen in 10D, the rear wheels 114 steer and the front wheels are locked in straight-ahead orientation as the truck drives up the aisle. Steering by the leading wheels allows accurate positioning in the aisle, and the four-wheel steering allows for easy transition between aisles.

The truck is preferably electrically powered. The truck is preferably an automatically guided vehicle (AGV), however it can be a stand-on / sit-on operator controlled truck, or remotely controlled. Preferably the AGV version can be integrated to the warehouse management system so all pallets can be automatically picked and placed.

Another variant is the addition of an operators station which may be attached to the sub-frame so that the operator can pick product at a height.

Claims

Claims 1. A fork lift apparatus comprising: a supporting frame for mounting a fork mechanism, the supporting frame in use defining a vertical direction, a first side and a second side; a fork structure mounted on the support frame, the fork structure comprising at least one arm for engaging with and lifting a load; a pivot provided on the fork structure, the pivot being arranged such that the fork structure can be rotated about the pivot in a generally vertical plane, between a first position wherein an arm of the fork structure is directed generally horizontally in the direction of the first side, and a second position wherein an arm of the fork structure is directed generally horizontally in the direction of the second side; and a fork lift mechanism for raising and lowering the fork structure.
2. The fork lift apparatus of claim 1, wherein the fork structure comprises a single arm rotatable through about 180 degrees between the first and second positions.
3. The fork lift apparatus of claim 1, wherein the fork structure comprises first and second arms which meet at a junction which defines an internal angle between the arms of from 70 to 110 degrees, said pivot being generally aligned with said junction.
4. The fork lift apparatus of any preceding claim, further comprising a translation mechanism for translating the fork structure in the direction of either the first side or the second side.
5. The fork lift apparatus of claim 4, wherein the translation mechanism is operable to translate the fork structure when in the first position between a recessed first position state wherein the fork structure is recessed within the supporting frame, and an extended first position state wherein an arm extends beyond the first side of the frame for engagement with a load.
6. The fork lift apparatus of claim 4 or 5, wherein the translation mechanism is operable to translate the fork structure when in the second position between a recessed second position state wherein the fork structure is recessed within the supporting frame, and an extended second position state wherein an arm extends beyond the second side of the frame for engagement with a load.
7. The fork lift apparatus of any preceding claim, wherein the frame defines a holding area.
8. The fork lift apparatus of claim 7, wherein the holding area is dimensioned to accommodate the fork structure.
9. The fork lift apparatus of claims, wherein the holding area accommodates the forks when retracted by the translation mechanism into a recessed state.
10. The fork lift apparatus of any preceding claim, wherein the fork lift mechanism comprises a short-lift mechanism for displacing the fork structure vertically by a sufficient distance to raise a load from contact with a supporting surface.
11. The fork lift apparatus of claim 10, wherein the frame comprises a structural member at ground level and wherein the short-lift mechanism is operable to displace the forks vertically by a sufficient distance to clear said structural member when the fork structure is translated relative to the frame.
12. The fork lift apparatus of any preceding claim, wherein the fork lift mechanism comprises a hoist mechanism for raising the fork structure vertically along the frame, the hoist mechanism being separate from a short-lift mechanism, if present.
13. The fork lift apparatus of claim 12, wherein the hoist mechanism comprises a cylinder-and-piston arrangement, which is connected to the fork structure via a chain.
14. The fork lift apparatus of claim 13, wherein the chain traverses a system of pulleys to multiply the displacement of the driving mechanism.
15. The fork lift apparatus of any preceding claim, wherein the frame is telescopic allowing it to be retracted and extended in height.
16. The fork lift apparatus of claim 3 or any claim dependent thereon, wherein the fork arms are disposed with an internal angle of about 90 degrees or more.
17. The fork lift apparatus of any preceding claim, further comprising a pair of said fork structures disposed with pivots aligned coaxially, whereby when both fork structures are in the first position, both fork structures have an arm extending in parallel towards the first side, and both fork structures being coupled to said fork lift mechanism to be raised and lowered together.
18. The fork lift apparatus of claim 17, wherein the pair of fork structures are rotationally coupled together such that when one is in the first position or second position, the other is similarly in that position.
19. The fork lift apparatus of any preceding claim, comprising a plurality of said fork lift mechanisms, each fork lift mechanism acting independently and being coupled to a set of one or more fork structures, such that a plurality of sets of fork structures are disposed alongside one another in a single frame allowing for the independent handling of side-by-side loads.
20. The fork lift apparatus of any preceding claim, when in the form of a fork lift truck, and further comprises motive means allowing the frame to be moved and steered as a vehicle
21. The fork lift apparatus of any of claims 1-19, when in the form of a crane which may be fixed in position or which may be traversed along an aisle with the first and second sides facing the sides of the aisle.