Claims
[1] A method of securing freight containers loaded on a deck of a ship, comprising: a vertical securing step of coupling the freight containers to each other in a vertical direction using a twistlock (13); and a lateral securing step of coupling adjacent left and right freight containers to each other using a coupler (21) and a variable type coupling device (22) such that the freight containers, placed in each layer, are integrated with each other along an entire width of the ship, wherein the lateral securing step is conducted after a process of loading the freight container using a harbor crane is completed.
[2] The method of securing the freight containers according to claim 1, wherein the coupler (21) comprises an insert protrusion (31) to be inserted between the adjacent left and right freight containers (10), and left and right coupling protrusions (32) symmetrically provided on opposite sides of the insert protrusion (31), the left and right coupling protrusions (32) being inserted into front holes (1 Ia) of corresponding corner fittings (11) of the adjacent left and right container (10), with a rotating latch (33) provided on an end of each of the left and right coupling protrusions (32), so that the coupler is coupled to the corner fittings (11) in a horizontal direction through the rotating latches (33) locked to the front holes (1 Ia) of the corner fittings (11) of the freight containers.
[3] The method of securing the freight containers according to claim 1, wherein the variable type coupling device (22) comprises: a casing (41), left and right movable protruding blocks (43) provided in the casing (41) so as to be extractable from and retractable into the casing (41) in horizontal directions, with a pair of locking protrusions (43b) provided on each of the left and right movable protruding blocks (43), the locking protrusions (43b) being fitted into respective side holes (1 Ib) of corresponding corner fittings (11) of adjacent left and right freight containers (10), a double worm gear (44) for extracting or retracting the left and right movable protruding blocks (43), external screws (45) engaged in a gear fashion with the worm gear (44) and engaged in a screw fashion with respective internal threads formed in the movable protruding blocks (43), and a manual handle (42) connected to and rotated along with the double worm gear (44), so that the variable type coupling device (22) is coupled to the side holes (1 Ib) of the corner fitting (11) of the freight containers. |
Description SECURING METHOD FOR FREIGHT CONTAINER
Technical Field
[1] The present invention relates to methods of securing freight containers.
Background Art
[2] Generally, freight containers are box type cases for efficiently and economically receiving and transporting cargo. The freight containers have a standardized width of 8 feet. Furthermore, the freight containers typically have lengths of 20 feet or 40 feet and heights of 8 feet, 8.5 feet or 9.5 feet.
[3] In addition, the freight containers are mainly made of material, such as wood, plywood, steel, light alloys or aluminum, and are classified into various kinds of containers, for example, for general cargo, for liquid, for refrigeration, etc., according to the kind of cargo to be handled.
[4] Such a freight container makes it possible to conveniently transport special cargo as well as general goods without requiring a separate outer packing process, thus reducing working time and expense. Furthermore, the freight container can prevent incidents such as the damage, loss or theft of cargo. In addition, in the case of the use of the freight container, a process of loading or unloading freight containers on a freight train, a freight car or a ship can be conducted using a machine in place of using human labor, so that there is an advantage in that the time required for the loading and unloading operation is reduced.
[5] To benefit from these advantages, recently, large ships have been used to transport a large number of freight containers to realize a reduction in transport costs, for example, five or more layers of containers are stacked on the deck of the ship. In the case of a modern type container ship, several thousand freight containers may be loaded on the deck of the container ship.
[6] Fig. 1 is a view illustrating a typical method of securing freight containers.
[7] As shown in the drawing, in the conventional method, to couple freight containers
10 with respect to the vertical direction, twistlocks 13 are coupled between the freight containers 10. Furthermore, to increase the strength of resistance against inclined loads and horizontal loads, the containers are fastened to the deck using lashing bars 14 and turnbuckles 15, which are provided in an "X" shape.
[8] However, as shown in the drawing, the X-shaped securing method can be used only with one or two layers of containers, because of problems pertaining to the length of each securing device and the fact that the weight is proportional to the length thereof. Furthermore, the securing force is varied depending on the thickness of the lashing
bars, and this may become a weak point. In addition, freight containers, which are disposed above the containers that are secured by the X-shaped securing method, are secured using only the twistlocks 13 in the vertical direction.
[9] Typically, the twistlocks 13 are provided on four respective corner fittings 11, which are provided in the lower corners of a container, on the ground when the container is raised by a crane at a harbor. Furthermore, when the container is loaded on a ship using the crane, that is, when the container is aligned with and placed on a lower container, the operation of vertically securing the containers to each other is automatically conducted by the spring operation of the twistlocks.
[10] However, when the containers are loaded or unloaded, to reduce working time through mechanization and ensure the safety of harbor workers, only twistlocks are used, and the work of laterally coupling the containers to each other is distasteful. The reason for this is that, because the conventional container lateral coupling method is a method in which a separate frame is fitted over each twistlock, disposed between the stacked containers, and adjacent containers in a lateral direction are coupled to each other via the frame, the harbor workers must conduct the work of installing or removing the frames on the upper surfaces of the containers while the crane is in operation. In other words, the above-mentioned work is very dangerous, and thus the harbor workers dislike doing the work.
[11] Furthermore, in the case of the modern container ship, five or more layers of containers are stacked on the deck, and each stack of containers is secured only in a vertical direction. That is, each stack of containers is independently fastened to a hatch cover or the deck. However, in this case, there are many risks according to the sea conditions. For example, under conditions of rough weather, such as a typhoon or rough waves, the container ship rolls severely, so that the stacked containers, which are fastened to each other, may be disconnected by the rolling force of the ship and fall into the sea. Moreover, in the case where the connection of the containers is broken in the middle portion of the stack of containers, the adjacent stack of containers and other stacks may subsequently collapse like dominoes. Disclosure of Invention Technical Problem
[12] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method of securing freight containers in which adjacent freight containers in each layer of containers are horizontally coupled to each other such that they can effectively withstand inclined loads and horizontal loads generated by rolling movement and other complex movement of a ship, thus ensuring safe container transportation.
Technical Solution
[13] In order to accomplish the above object, the present invention provides a method of securing freight containers loaded on a deck of a ship, including: a vertical securing step of coupling the freight containers to each other in a vertical direction using a twistlock; and a lateral securing step of coupling adjacent left and right freight containers to each other using a coupler and a variable type coupling device such that the freight containers, placed in each layer, are integrated with each other along an entire width of the ship, wherein the lateral securing step is conducted after a process of loading the freight container using a harbor crane is completed.
[14] The coupler may include an insert protrusion to be inserted between the adjacent left and right freight containers, and left and right coupling protrusions, which are symmetrically provided on opposite sides of the insert protrusion, wherein the left and right coupling protrusions are inserted into corresponding corner fittings of the adjacent left and right container, with a rotating latch provided on an end of each of the left and right coupling protrusions, so that the coupler is coupled to the corner fittings through front holes of the corner fittings in a horizontal direction.
[15] The variable type coupling device (22) may include a casing, left and right movable protruding blocks provided in the casing so as to be extractable from and retractable into the casing in horizontal directions, with a pair of locking protrusions provided on each of the left and right movable protruding blocks, the locking protrusions being fitted into respective side holes of corresponding corner fittings of adjacent left and right freight containers, a double worm gear for extracting or retracting the left and right movable protruding blocks, external screws engaged in a gear fashion with the worm gear and engaged in a screw fashion with respective internal threads formed in the movable protruding blocks, and a manual handle connected to and rotated along with the double worm gear, so that the variable type coupling device is coupled to the side holes of the corner fitting of the freight containers.
Advantageous Effects
[16] According to the method of securing freight containers according to the present invention, the freight containers can effectively withstand inclined loads and horizontal loads generated when a ship rolls, thus reducing the deformation and damage of the freight containers, and ensuring safe container transportation. Brief Description of the Drawings
[17] Fig. 1 is a view illustrating a conventional method of securing freight containers;
[18] Fig. 2 is a view illustrating a method of securing freight containers, according to an embodiment of the present invention;
[19] Fig. 3 is a detailed view showing the coupling between a coupler and corner fittings
used in the freight container securing method according to the present invention;
[20] Fig. 4 is a detailed view showing the coupling between a variable type coupling device and the corner fittings used in the freight container securing method according to the present invention;
[21] Fig. 5 is a view showing the internal construction of the variable type coupling device used in the freight container securing method according to the present invention; and
[22] Fig. 6 is a partially exploded perspective view corresponding to Fig. 5.
[23] <Description of the elements in the drawings>
[24] 10: freight container 11: corner fitting
[25] l la: front hole 1 Ib: side hole
[26] 13: twistlock 14:lashing bar
[27] 15: turnbuckle 16: hatch cover
[28] 21: coupler
[29] 22: variable type coupling device
Best Mode for Carrying Out the Invention
[30] The present invention relates, in general, to methods of securing freight containers and, more particularly, to a method of securing freight containers which can effectively withstand external force, such as inclined loads or horizontal loads, generated by movement of the ship, thus ensuring stable freight container transportation. Mode for the Invention
[31] Hereinafter, a method of securing freight containers according to a preferred embodiment of the present invention will be described with reference to the attached drawings.
[32] Fig. 2 is a view illustrating the freight container securing method according to the present invention. As shown in the drawing, the method of securing freight containers in a vertical direction using twistlocks is the same as that of the conventional art.
[33] In each layer of freight containers, adjacent freight containers are coupled to and integrated with each other using a coupler 21 or a variable type coupling device 22. This drawing shows a container securing example in which first through third layers of freight containers are integrated with each other. In this container securing method, freight containers, which are placed in the lower portion of a stack of containers, are integrated with each other so that the lower part of the stack of containers forms a single body like a single container. Only two or three layers of containers from the top are secured by twistlocks. Therefore, the present invention can effectively withstand inclined loads and horizontal loads generated by rolling movement of the ship and by other types of movement thereof, thus ensuring stable transportation.
[34] Furthermore, depending on the height to which freight containers are stacked, the number of layers for which the lateral securing is required can vary. Thus, the present invention makes it possible to stack freight containers to a relatively high position.
[35] Fig. 3 is a detailed view showing the coupling between the coupler 21 and corner fittings 11. As shown in the drawing, the bilateral coupler 21 includes an insert protrusion 31, which is provided at the medial position, and coupling protrusions 32, which are symmetrically provided on opposite sides of the insert protrusion 31.
[36] The insert protrusion 31 of the coupler 21 is inserted between adjacent containers
10. The left coupling protrusion 32 is fitted into a front hole 1 Ia of a right corner fitting of the left container 10, and the right coupling protrusion 32 is fitted into a front hole 1 Ia of a left corner fitting of the right container 10. In addition, a rotating latch 33 is provided on the end of each of the left and right coupling protrusions 32.
[37] The left and right coupling protrusions 32 are oriented in one direction from the junction surface corresponding thereto. Therefore, after the process of stacking the freight containers using a crane has been completed, the rotating latches 33 are horizontally inserted into the front holes 11a, which are formed in the corner fittings. Subsequently, latch control levers 34, which are integrally rotated with the rotating latches 33, are rotated at 90°, so that, even if the ship excessively rolls, the coupler 21 is prevented from being removed from the corner fittings.
[38] Fig. 4 is a view showing the coupling between a variable type coupling device 22 and the corner fittings 11 according to the present invention.
[39] Typically, freight containers, which are loaded on the deck of the ship, are placed on hatch covers 16. Furthermore, the several hatch covers 16, which are separated from each other, are provided in the lateral direction of the ship. Therefore, at each hatch cover, gaps at which freight containers are spaced apart from each other are constant. However, a gap between freight containers increases at a position between two adjacent hatch covers. In addition, because the positions at which the hatch covers are placed are slightly varied in processes of opening and closing the hatch covers, the gap between associated freight containers may be different every time.
[40] The variable type coupling device 22 is coupled to side holes 1 Ib of the corner fittings 11 of the freight containers 10 and is constructed such that the length thereof can be varied to respond to a change in the gap between the freight containers. The variable type coupling device 22 is used to couple the associated freight containers, which are placed on the two adjacent hatch covers, to each other.
[41] Fig. 5 is a view showing the internal construction of the variable type coupling device 22 used in the freight container securing method according to the present invention.
[42] The variable type coupling device 22 includes left and right movable protruding
blocks 43, each of which has a pair of locking protrusions 43b which are fitted into the side holes 1 Ib of the corresponding corner fittings 11 of the adjacent containers, a double worm gear 44, which is operated to extend or retract the left and right movable protruding blocks, and a manual handle 42, which operates the double worm gear. The variable type coupling device 22 further includes external screws 45, which are engaged in gear fashion with the worm gear 44 and are threadedly engaged with respective internal threads formed in the movable protruding blocks, and a casing 41 for supporting these components.
[43] As shown in the drawing, the left and right movable protruding blocks 43, which are separately provided, are coupled to each other through the external screws. Depending on the direction in which a user manipulates the manual handle 42, the locking protrusions 43b of the movable protruding blocks 43 are inserted into or removed from the respective side holes 1 Ib of the corresponding corner fittings 11. As such, the variable type coupling device serves to couple the stacks of containers, which are placed on the adjacent hatch covers, to each other to ensure structural continuity, thus increasing resistance to inclined loads and horizontal loads.
[44] The operation and effect of the embodiment of the freight container securing method according to the present invention will be described herein below.
[45] As shown in Figs. 2 through 4, in the freight container securing method according to the present invention, in a process of loading freight containers on the hatch covers 16, which have approximately rectangular frame shapes, on the front part of the ship, freight containers are stacked to various heights such that containers that are at the same height, are arranged in a lateral direction. At this time, first through third layers of containers, which must be secured using the couplers 21 and the variable type coupling devices 22, are vertically secured using twistlocks 13 such that they are aligned with each other in the horizontal direction. Fourth and subsequent layers of containers can be stacked without requiring particular attention, because it is unnecessary to set the height of adjacent containers such that they are aligned with each other.
[46] After the process of loading the containers using the crane has been completed, some desired containers of the stack of containers placed on each hatch cover are first coupled to each other using the couplers 21 by harbor workers. For this process, ladders may be necessary. Furthermore, if a gap between the adjacent containers is too narrow, so that the coupler 21 cannot be inserted into the gap, after the gap between the containers is adjusted using a lever or a separate hydraulic device, the coupler is inserted into the gap and the locking process is conducted.
[47] After the process of coupling the couplers 21 has been completed, the installation of the variable type coupling devices 22 is conducted. At this time, the variable type
coupling devices are raised and installed using a ladder and a pulley device.
[48] After the installation has been completed, a safety cable is coupled between each variable type coupling device and the corresponding front hole 1 Ia of the corner fitting 11, such that, even if the coupling device 22 is undesirably removed by excessive movement of the ship, the container or the coupling device is prevented from falling onto the deck.
[49] Meanwhile, a process of unloading the containers is conducted in a sequence opposite the loading process.
[50] The operation of the variable type coupling device 22 used in the freight container securing method according to the present invention will be explained herein below.
[51] The coupling device 22 is disposed at a position such that the locking protrusions
43b of the movable protruding block 43, which is provided at one end of the coupling device 22, are inserted into respective side holes 1 Ib of corresponding corner fittings 11 of the containers 10. Thereafter, when the handle 42 is rotated, the movable protruding blocks 43 are extracted from the casing 41, so that the locking protrusions of the opposite movable protruding block 43 are inserted into the respective side holes 1 Ib of the corresponding corner fitting 11. That is, the left movable protruding block 43 is coupled to the right corner fittings 11 of the left container 10, and the right movable protruding block 43 is coupled to the left corner fittings 11 of the right container 10.
[52] Here, in the variable type coupling device 22, the double worm gear 44, which is connected to the manual handle 42, rotates the external screws 45, which are symmetrically provided at positions above and below the worm gear 44, in opposite directions. Therefore, to move the movable protruding blocks 43 in opposite directions using the external screws 45, which are provided parallel to each other, threads are formed on left and right parts of each external screw 45 in opposite directions, and the threads of the upper external screw 45 are oriented in the direction opposite those of the lower external screw 45. According to the operational principle of the worm gear, the variable type coupling device 22 generates a relatively large force in the direction in which the left and right containers move away from each other, thus the coupling device 22 is reliably locked to the containers.
[53] To release this state, the user rotates the manual handle 42 in the opposite direction.
Then, the external screws, which are operated in conjunction with the manual handle, are rotated in the direction in which the movable protruding blocks are removed from the side holes 1 Ib of the corner fittings 11, thus releasing the locked state.
[54] Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, the present invention is not limited to the above embodiment. Those skilled in the art will appreciate that various modifications, additions and sub-
stitutions are possible, without departing from the scope and spirit of the invention disclosed in the accompanying claims.
[55] Therefore, such modifications, additions and substitutions must be regarded as falling within the bounds of the present invention. Industrial Applicability
[56] As described above, in a method of securing freight containers according to the present invention, having the above-mentioned construction and operation, a securing means is used to provide horizontal structural continuity to stacks of containers vertically coupled to each other, thus reliably maintaining the secured state of the stacks of containers, such that the containers can effectively withstand inclined loads and horizontal loads using their own strength. Therefore, the present invention can reduce deformation of and damage to the containers, and makes it possible to stack the containers higher, thus enhancing economic profitability.