NO345212B1

NO345212B1 - Forerunner unit to be hung from a crane for protecting operators during heave movements

Info

Publication number: NO345212B1
Application number: NO20190283A
Authority: NO
Inventors: Kristian Smith
Original assignee: Kolberg Caspary Lautom As
Priority date: 2019-03-01
Filing date: 2019-03-01
Publication date: 2020-11-09
Also published as: NO20190283A1

Description

Field of invention

[001] The invention relates to a forerunner unit for handling heave movements for use in a crane, for instance at sea. More specifically it relates to a device designed to protect operators and surroundings from a freely moving and heavy hook block or similar hoisting equipment and to handle, for instance, heave movements of vessels involved in loading / unloading operations of heavy goods.

Background

[002] The off-shore industry transport large amounts of goods by supply ships to and from installations like oil platforms and windmill parks. The loading and unloading must be done when exposed to wind, waves and currents. Consequently a lot of time is lost due to bad weather.

[003] Another problem is heave movements of vessels involved in loading / unloading operations at sea. This problem limits the window in which an operator may safely attach hooks and cargo. The hook and hook block is heavy and often extra equipment is connected to the hook. It is dangerous to operate in the nearby area of the hook and hook block during heave movements.

[004] The applicant has developed a device for rotational control. This device is relatively heavy and represents a danger for an operator when attaching a hook of the said device to the load to be lifted due to its size and weight.

[005] GB 2561909 A describes an apparatus and method for reducing heave motion in a load suspended from a vessel mounted crane. The apparatus comprises: a main chassis; a drive assembly mounted to the main chassis and comprising a drive gear or pinion 235; a geared rotating mechanism 160 translatably (in rotation) disposed in the main chassis, and running along a circumferential path; and a lift wire, rope or chain 170 secured to the geared rotating mechanism. The drive gear or pinion engages the geared rotating mechanism such that rotation of the drive gear or pinion (such as by a motor 220) is coupled to translation of the rotating mechanism in the main chassis, thereby lifting or lowering the lift wire, rope or chain. Control circuitry is operative to command the drive assembly to cause the geared rotating mechanism to translate in the main chassis at least in part based on the heave motion detected by a sensor.

[006] US 2015129529 describes an apparatus for use in combination with a sensor operative to detect heave motion. The apparatus comprises a main chassis, a drive assembly, a lifting column, a pinion, and control circuitry. The drive assembly is mounted to the main chassis and comprises a drive gear. The lifting column is translatably disposed in the main chassis and comprises a linear gear rack that runs along a longitudinal axis. The pinion is rotatably coupled to the rotation of the drive gear and engages with the linear gear rack such that rotation of the pinion is coupled to translation of the lifting column in the main chassis along the longitudinal axis. Finally, the control circuitry is operative to command the drive assembly to cause the lifting column to translate in the main chassis at least in part based on the heave motion detected by the sensor.

[007] To resolve these problems a forerunner unit has been developed. The solution is to detach the hook from the hook block or similar equipment, lower the hook to the load to be lifted and let the operator attach the load to the hook and vacate the site before the device is lowered and re-attached to the hook.

Summary of the invention

[008] The invention describes forerunner unit to be hung from a crane for protecting operators from freely moving hoisting equipment and loads to be lifted during loading / unloading operations at sea comprising a load bearing forerunner frame directly or indirectly attached to a hook block and having a docking space, and a hook with a first locking structure at the top of the hook, wherein the first locking structure is adapted to fit inside the docking space and is connected to a forerunner wire at the top. The forerunner unit further comprises a winch mounted on the frame for operating the forerunner wire, and a releasable brake mounted on the winch for releasing the winch when the pull on the forerunner wire exceeds a predetermined threshold. The forerunner unit further comprises a second locking structure positioned inside the docking space which is mating with the first locking structure, thus preventing downward movement of the hook in a locked position, and wherein the hook and wire are free to move vertically in an unlocked position. The wire and winch is not designed to take the weight of the load to be lifted.

[009] In another aspect the invention describes a method for use of the forerunner unit when attaching the hook to an object to be lifted, wherein the method comprises the steps of:

a) switching the locking structures to the unlocked position,

b) lowering the hook to the object to be lifted by means of the winch,

c) manually attaching the object to the hook,

d) removing personnel from the site,

e) lowering the hook block while simultaneously reeling in the wire by means of the winch,

f) docking the first locking structure in the docking space,

g) switching the locking structures to the locked position, and

h) lifting the object.

Short description of figures.

[010] To improve the understanding of the invention a number of figures showing actual embodiments is provided. Like numerals in different figures are linked to the same feature.

[011]

Fig. 1 shows an embodiment of a forerunner unit.

Fig. 2 shows the embodiment of fig. 1 with the forerunner frame opened and the locking bolt in a locked position.

Fig. 3 shows the locking bolt in the process to be opened.

Fig. 4 shows the locking bolt in an open position.

Fig. 5 shows a sectioned and detailed view of the locking bolt in the open position.

Fig. 6 shows the forerunner unit when lowering the hook.

Detailed description

[012] In the following we will assume that the forerunner unit is hanging vertically as in its usual position. In a first embodiment the invention describes a forerunner unit 1 for use in a crane, for instance at sea.

[013] In the first embodiment the forerunner unit comprises a load bearing forerunner frame 3 directly or indirectly attached to a hook block and having a docking space 9. Furthermore, the forerunner unit comprises a hook 4 with a first locking structure 5 at the top of the hook. The first locking structure 5 is adapted to fit inside the docking space and is connected to a forerunner wire 6 at the top. The wire is rolled on to a wire drum which is operated by a winch 7 mounted on the frame 3. The winch has a releasable break 17, or release mechanism 17, which releases the wire at a predetermined threshold of pull on the wire. This feature is important because if the boat is heaving down with an operator nearby, the load to be lifted will not be lifted off the deck and be in danger of squeezing the operator against other objects. The brake, or release mechanism, on the winch will be released and the load will remain in the same place on deck, while the winch is still pulling with the same magnitude of force as the threshold. The release mechanism 17 should be able to lift the hook and possibly other lifting equipment such as chains or a lifting frame. For this feature to function the weight of the load to be lifted must be significantly more than the predetermined releasing threshold. Also, the length of the forerunner wire left on the winch must be more than the maximum heave movement.

[014] In one embodiment the release mechanism is integral in the electrical motor 23. In another embodiment the release mechanism is a disc or drum brake mounted between the wire drum and the motor.

[015] In the first embodiment the forerunner unit further comprises a second locking structure 8 positioned inside the docking space 9 and mating with the first locking structure, thus preventing downward movement of the hook 4 in a locked position, and wherein the hook 4 and wire 6 is free to move vertically in an unlocked position.

[016] In one embodiment a load bearing swivel is mounted between the hook and the hook block 16.

[017] In another embodiment, as shown in fig. 1 and 2, the forerunner unit 1 comprises a load bearing forerunner frame 3, which is rotationally locked to the load bearing structure 2 The forerunner unit further comprises a hook 4 rotationally fixed to the first locking structure 5. In one embodiment the first locking structure is a load bearing locking ring 21 at the top of the hook, wherein the locking ring 21 is adapted to fit inside the docking space and is connected to a wire 6 at the top. The wire is in turn connected to a winch 7 mounted on the frame for operating the wire. In the second embodiment of the forerunner a brake on the winch is not necessary if operation is executed in conditions without heave, ie on land or fixed structures.

[018] A pulley is mounted near the centerline of the load bearing structure such that the wire may be lowered along the centerline. The mouth of the docking space is preferably rounded in order to ease the docking of the locking ring.

[019] In one embodiment of the forerunner unit the second locking structure is a load bearing locking bolt 8 switchable between a locked and unlocked position, wherein the locking bolt is preventing downward movement of the hook 4 and ring 21 in the locked position, and the hook 4 and ring 21 are free to move vertically in the unlocked position.

[020] In one embodiment the locking 5 ring and hook 4 are integrated in one solid piece. In another embodiment the ring 21 and hook 4 are hingedly attached with a horizontal rotational axis as shown in the figures. It is also conceivable with two horizontal rotational axis (like a cardan joint).

[021] In one embodiment an actuator or solenoid 10 is provided for enabling a transition of the load bearing bolt 8 between the locked and unlocked position. In one embodiment the actuator or solenoid is connected to an actuator hook which has two positions: a locked position and an unlocked position as illustrated in fig 4 and 3 respectively. The locking ring is provided with a bolt release structure 14 and the locking bolt is hingedly mounted to the forerunner frame 3. In one embodiment the bolt release structure 14 is a plate 14 at least covering the lower parts of the locking ring 21 and extending in a lateral direction perpendicular to the plate such that the locking bolt is moved to an unlocked position where it does not interfere with the locking ring when the locking ring is moving downwards. Preferably the locking bolt is pre-tensioned towards the locked position, but gravity may suffice in some configurations. As illustrated in fig. 1 – 4 the locking ring should be resting on the locking bolt which in turn rests on reciprocal features 16 on the forerunner frame 3. Above the locking ring it should be enough free space left of the docking space 9 to hoist the locking ring sufficiently upwards to allow unlocking of the locking bolt. In other words, the locking bolt and reciprocal features must be positioned such that the locking ring can be lifted further up in the docking space to relieve the weight of the hook from the locking bolt. The wire and the winch are not designed to take the weight of the load. Therefore, this operation can only take place when no load is attached to the hook 4.

[022] In another embodiment (not shown) the locking bolt comprises a pitch rack and is moved between locked and unlocked position by means of a cogwheel.

[023] In one embodiment, shown in figures 3 - 5, the locking bolt is switched to the unlocked position by lifting the locking ring. The bolt release structure lifts the locking bolt and when the locking bolt reaches the unlocked position an actuator arm 12 with a hook engages a holding indent 15, holding the locking bolt in the unlocked position thus allowing the hook 4 to be lowered towards the load to be lifted as shown in figure 6.

[024] A method for use of the forerunner unit when attaching the hook 4 to an object to be lifted is described below. The method comprises the steps of:

a) switching the locking bolt to the unlocked position,

b) lowering the hook to the object to be lifted by means of the winch,

c) manually attaching the object to be lifted to the hook,

d) removing personnel from the site,

f) docking the first locking structure 5 in the second locking structure 8 in the docking space,

g) switching the locking structures to the locked position, and

h) lifting the object.

[025] When detaching the load that was lifted after landing the object in a desired position the following steps are carried out:

i) hoisting the hook block to a safe height while reeling out the wire (8) at least to the same extent the hook block was hoisted,

j) manually detaching the load that was lifted from the hook.

At this stage it is possible to move the hook to further loads to be lifted and restart at step c) and repeat until all lifting is done.

Inventory

1. Forerunner unit

2. Load bearing structure

3. Forerunner frame

4. Hook

5. First locking structure

6. Wire

7. Winch

8. Second locking structure

9. Docking space

10. Actuator / solenoid

11. Pulley

12. Actuator hook

13. Pre-tensioning unit / spring

14. Bolt release structure

15. Holding indent for actuator hook

16. Reciprocal features

17. Releasable break / release mechanism

21. Load bearing locking ring

22. Load bearing locking bolt

23. Electrical motor

Claims

1. Forerunner unit to be hung from a crane for protecting operators from freely moving hoisting equipment and loads to be lifted during heave movements in loading / unloading operations at sea, wherein the forerunner unit comprises:

a load bearing forerunner frame (3) directly or indirectly attached to a hook block and having a docking space (9),

a hook (4) with a first locking structure (5) at the top of the hook, wherein the first locking structure (5) is adapted to fit inside the docking space and is connected to a forerunner wire (6) at the top,

a winch (7) mounted on the frame for operating the forerunner wire, , characterized by

a release mechanism (17) mounted on the winch for releasing the winch when the pull on the forerunner wire exceeds a predetermined threshold,

a second locking structure (8) positioned inside the docking space (9) and mating with the first locking structure, thus preventing downward movement of the hook (4) in a locked position,

wherein the hook (4) and wire (6) is free to move vertically in an unlocked position, and

wherein the wire and the winch are not designed to take the weight of the load to be lifted.

2. Forerunner unit according to claim 1, wherein the release mechanism is integral in an electrical motor (23).

3. Forerunner unit according to claim 1, wherein the release mechanism is a disc or drum brake mounted between the wire drum and a motor (23).

4. Forerunner unit according to claim 1, wherein the forerunner wire (6) is running over a pulley positioned above the centerline of the docking space.

5. Forerunner unit according to claim 1, wherein a load bearing swivel is mounted between the hook and the hook block.

6. Forerunner unit according to claim 1, wherein the hook is rotationally fixed to the hook block.

7. Forerunner unit according to claim 1, wherein the first locking structure (5) is a load bearing locking ring (21) that fits inside the docking space, and wherein the second locking structure is a load bearing locking bolt (22) switchable between a locked and unlocked position, wherein the locking bolt is resting in reciprocal features (16) in the forerunner frame and the locking ring is resting on the bolt, when in the locked position.

8. Forerunner unit according to claim 7, wherein the locking ring can be lifted further up in the docking space to relieve the load from the locking bolt, and a bolt release structure (14) is provided inside the locking ring and the locking bolt is hingedly mounted in one end to the forerunner frame, such that when the locking ring is lifted the locking bolt is lifted and when the locking bolt reaches the unlocked position an actuator arm (12) with a hook engages a holding indent (15), holding the locking bolt in the unlocked position thus allowing the hook (4) to be lowered from the forerunner unit.

9. Forerunner unit according to claim 8, wherein a bolt release structure (14) is a plate (14) at least covering the lower parts of the locking ring (21) and extending in a lateral direction perpendicular to the plate such that the locking bolt is moved to a position where it does not interfere with the locking ring when moving downwards.

10. Forerunner unit according to claim 8, wherein an actuator or solenoid (10) is provided for enabling a transition of the load bearing locking bolt (22) between a locked and unlocked position.

11. Forerunner unit according to claim 8, wherein the locking bolt is pre-tensioned towards the locked position.

12. Method for use of the forerunner unit according to claim 1 when attaching and detaching the hook (4) to an object to be lifted, wherein the method is characterized by the steps of:

a) switching the locking bolt (22) to the unlocked position,

b) lowering the hook 4 to the object to be lifted by means of the winch,

c) manually attaching the object to the hook,

d) removing personnel from the site,

e) lowering the hook block while simultaneously reeling in the wire by means of the winch 7,

f) docking the first locking structure (5) in the second locking structure (8) in the docking space (9),

g) switching the locking structures to the locked position, and

h) lifting the object and landing the object in a desired position,

i) hoisting the forerunner unit to a safe height while reeling out the wire (8) to at least the same extent the unit is hoisted,

j) manually detaching the load that was lifted from the hook, and

k) move hook to next load to be lifted and repeat from c) until all lifting is done.