Abstract:
A crane spreader for use in lifting a container includes an attachment unit, a head block, a frame unit, a position adjustment unit and a fixation unit. The attachment unit detachably attaches the crane spreader to an upper surface of the container. The head block has a pulley connected to a trolley of a crane through a cable and coupled to the attachment unit to restrict a horizontal movement the attachment unit with respect to the head block. The frame unit is supported by the head block to be horizontally movable with respect to the head block, the frame unit being disposed below the head block with a gap therebetween. The position adjustment unit aligns the frame unit with the container by displacing the frame unit with respect to the attachment unit. The fixation unit engages the container with the frame unit.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates so a crane spreader and a method for automatically landing the same; and, more specifically, to a crane spreader and an auto landing method which is capable of accurately and quickly landing the crane spreader which is swayed by various external factors. 
       BACKGROUND OF THE INVENTION 
       [0002]    As the volume of trade between countries or between cities significantly increases, the traffic volume is also increasing. In particular, a traffic volume through a sea route where the shipping cost is low is rapidly increasing. With such a rapid increase of traffic volume, an ultra large vessel such as a 10,000 TEU vessel has emerged, which is capable of loading a large volume of cargo. Furthermore, the scale of a container terminal is gradually increasing enough to berth such an ultra large vessel. Such a container terminal includes a plurality of large cranes installed therein, which are capable of loading and unloading containers on and from an ultra large vessel. 
         [0003]    In general, a container crane is equipment for loading and unloading containers between a vessel and a quay. The loading and unloading speed of the container crane is a core factor which determines the maximum cargo processing ability of the entire quay. 
         [0004]      FIG. 1  is a schematic view of a conventional container crane which is a facility used for loading and unloading containers. Referring to  FIG. 1 , the conventional container crane includes a gate-type frame and a trolley T. The gate-type frame including a post P and a beam B is mounted on a chassis D which has a plurality of wheels W. The trolley T lifts a container N while moving on the beam B in a transverse direction. 
         [0005]    Such a container crane transfers the container N while being moved in a transverse direction (e.g. forward or backward) by the drive of the wheels W or rotated by the direction change of the wheels W. 
         [0006]    Meanwhile, the trolley T includes a spreader S which is engaged with the container N. The spreader S is constructed in such a flexible manner as to be engaged with a variety of containers having different widths and lengths. 
         [0007]      FIG. 2  shows that a conventional spreader  20  is transferring a container  10 . The spreader  20  includes a body  21  and a telescopic frame  22  which can be expanded and contracted with respect to the body  21 . Since the telescopic frame  22  can be expanded and contracted, the length of the telescopic frame  22  may be adjusted to such a proper length as to coincide with the size of the container  10 . 
         [0008]    Furthermore, the conventional crane controls the longitudinal and transverse positions of the spreader  20  by adjusting the longitudinal and transverse positions of the trolley T, and also controls the rotational position of the spreader  20  by simultaneously or sequentially driving a rotational driving device (M). 
         [0009]    Meanwhile, twist locking mechanisms  24  formed at end portions of the telescopic frame  22  are inserted to corner castings  11  formed at four corners of the container  10 , thereby preventing the container  10  from rotationally deviating from the spreader  20 . 
         [0010]    As such, when the telescopic frame  22  is aligned with the container  10 , flippers  23  installed at four corners of the telescopic frame  22  are engaged with the corner castings  11  formed at the four corners of the container  10 . Then, the container  10  is engaged with the spreader  20 . 
         [0011]    However, in such a conventional container crane, it is difficult to accurately control the relative position of the spreader with respect to the container, because of external factors in which an anchored container vessel pitches or rolls or the spreader suspended to the trolley sways in the wind. 
         [0012]    Conventionally, when aligning a spreader with a container, a crane operator in a control room depends on his eyes. Therefore, when the position of the container or the spreader is swayed by an external factor, it is very difficult to accurately control the relative position therebetween. As a result, it takes a lot of operation time to engage the spreader with the container and the operation efficiency decreases. 
         [0013]    In order to solve such a problem, the present applicant has proposed an apparatus and method which attaches a frame unit of a crane spreader to a certain position of the upper surface of a container by using an attachment member, and then moves the frame unit with respect to the attachment member such that the spreader is positioned at the accurate position on the container (refer to Korean Patent Application No. 2009-0074305). This apparatus has a structure that a head block, on which pulleys connected to a trolley through a cable are installed, is fixed to the frame unit. In this structure, the frame unit of the crane spreader is fixed to a proper Position of the upper surface of the container by using the attachment member, and then the frame unit is aligned with a container by adjusting the relative position of the frame unit on the basis of the attachment member. Therefore, although a container vessels pitches or rolls, the crane spreader may be relatively quickly and accurately landed on the container. 
         [0014]    In many cases, the position of the container with respect to the head block needs to be precisely controlled even after the container is engaged with the spreader, particularly in a state in which the container is lifted. However, in accordance with the above apparatus in which the head block is fixed so as not to relatively move with respect to the frame unit, there is a problem in that the relative position movement between the head block and the container is impossible after the crane spreader is engaged with the container. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention provides an apparatus and method which is capable of precisely adjusting the position of a container with respect to a head block connected to a trolley, after the container is engaged with a crane spreader. 
         [0016]    Further, the present invention provides an apparatus and method which is capable of precisely adjusting the position of a spreader with respect to a head hock connected to a trolley, before landing the spreader onto a container. 
         [0017]    In accordance with an aspect of the present invention, there is provided a crane spreader for use in lifting a container. The crane spreader includes: an attachment unit for detachably attaching the crane spreader to an upper surface of the container; a head block having a pulley connected to a trolley of a crane through a cable and coupled to the attachment unit to restrict a horizontal movement of the attachment unit with respect to the head block; a frame unit supported by the head block to be horizontally movable with respect to the head block; a position adjustment unit for aligning the frame unit with the container by displacing the frame unit with respect to the attachment unit; and a fixation unit for engaging the container with the frame unit when the frame unit is aligned with the container. 
         [0018]    In accordance with the second aspect of the present invention, there is provided a crane spreader for use in lifting a container. The crane spreader includes: a head block having a pulley connected to a trolley of a crane through a cable; a frame unit supported by the head block to be horizontally movable with respect to the head block, the frame unit being disposed below the head block with a gap therebetween; a position adjustment unit, including a center housing, for moving the center housing with respect to the frame unit; and a shaft portion restricting a horizontal movement, of the head block with respect to the center housing. 
         [0019]    In accordance with a second aspect of the present invention, there is provided a method for use in landing a crane spreader. The crane spreader includes an attachment unit attached to an upper surface of a container, a head block connected to a trolley through a pulley, and a frame unit being horizontally movable with respect to the attachment and coupled to be horizontally movable with respect to the head block. The method includes: detecting the position of the container; attaching the attachment unit to an upper surface of the detected container; detecting the relative position of the frame unit with respect to the container, and calculating a position movement path of the frame unit on the basis of the attachment unit; aligning the frame unit with the container by moving the frame unit on the basis of the attachment unit along the calculated path; and detaching the attachment unit from the container, and adjusting the relative position of the frame unit with respect to the head block, after aligning the frame unit with the container. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The objects and features of the present invention will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which: 
           [0021]      FIG. 1  is a schematic view of a conventional container crane; 
           [0022]      FIG. 2  shows a conventional crane spreader; 
           [0023]      FIG. 3  is a front view of a crane spreader in accordance with an embodiment of the present invention; 
           [0024]      FIG. 4  is a perspective view of the crane spreader in accordance with the embodiment of the present invention; 
           [0025]      FIG. 5  is a plan view illustrating a position adjustment unit of the crane spreader in accordance with the embodiment of the present invention; 
           [0026]      FIG. 6  illustrates a state in which the crane spreader in accordance with the embodiment of the present invention is not aligned with a container; 
           [0027]      FIG. 7  depicts a state in which the crane spreader in accordance with the embodiment of the present invention is aligned with a container; 
           [0028]      FIG. 8  shows a state in which a head block is relatively moved with respect to the container after the crane spreader is engaged with the container; and 
           [0029]      FIG. 9  presents a state in which a frame unit is relatively moved with respect to the head block after the crane spreader is engaged with the container. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0030]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that they can be readily implemented by those skilled in the art. 
         [0031]      FIG. 3  is a front view of a crane spreader in accordance with an embodiment of the present invention.  FIG. 4  is a perspective view of the crane spreader of  FIG. 3 .  FIG. 5  is a plan view illustrating a position adjustment unit of the crane spreader.  FIGS. 6 and 7  are plan views illustrating a process in which the crane spreader in accordance with the embodiment of the present invention is aligned with a container.  FIG. 8  is a diagram illustrating a state in which a head block is relatively moved with respect to the container after the crane spreader is coupled to the container.  FIG. 9  is a diagram illustrating a state in which a frame unit is relatively moved with respect to the head block after the crane spreader is coupled to the container. 
         [0032]    Referring to  FIGS. 3 and 4 , the crane spreader  20  in accordance with the embodiment of the present invention includes a head block  100 , a frame unit  110 , and an adhesion unit  120 . Through a cable (not shown), the head block  100  is connected to and supported by a trolley (refer to  FIG. 1 ). The frame unit  110  is supported by the head block  100 . The attachment unit  120  is disposed to pass through the head block  100  and the frame unit  110  and attached to the upper surface of a container. 
         [0033]    The head block  100  is connected to the trolley by the cable, and the cable hanging down from the trolley is wound halfway around a head pulley  102  installed in the head block  100 , and then goes back to the trolley. A driving motor winds up this cable, thereby lifting the spreader  20  (including the head block  100 ). 
         [0034]    Support pulleys  101  for holding the frame unit  110  are installed under the head block  100 . The support pulleys  101  support support pulleys  114  installed at corresponding positions on the frame unit  110 , through a wire. Between the head block  100  and the frame unit  110 , four pairs of support pulleys  101  and  114  may be installed at four corners of the head block  100  and at the corresponding positions on the frame unit  110 , respectively, in order to stably support the frame unit  110 . As such, since the head block  110  is supported by the plural pairs of support pulleys  101  and  114  and wires connecting between the support pulleys  101  and  104 , the frame unit  110  may be relatively moved in a direction parallel to the surface of the head block  100 . 
         [0035]    In this embodiment, it has been described that the head block  100  supports the frame unit  110  by using the support pulleys  101  and  114  and the wires. However, the frame unit  110  may be supported by chains, formed of a metallic material or other materials capable of providing a reasonable strength, and support portions for supporting the chains, which are formed on each of the head block  100  and the frame unit  110 . Such a structure is also included in the scope of the present invention. 
         [0036]    The head block  100  has a through-hole  103  formed in the center thereof, through which a shaft portion  122  of the attachment unit  120  passes. Under the through-hole  103 , support rollers  124  are provided in four directions along the circumference of the through-hole  103 . The support rollers  124  support the shaft  122  so as to move in the axial direction. The through-hole  103  is formed to have a slightly larger diameter than the diameter of the shaft  122 , and the support rollers  124  guide the shaft  122  in a direction perpendicular to the head block  100 . Therefore, the shaft  122  may vertically move within the through-hole without being contacted with the through-hole. At this time, the plurality of support rollers  124  may be continuously formed in the direction perpendicular to the head block  100  such that the shaft  122  may be stably guided in the direction perpendicular to the head block  100 . 
         [0037]    Next, the frame unit  110  will be described. The frame unit  110  includes an upper frame  111 , a lower frame  112 , and supports  113 . The upper frame  111  forms an upper plate of the frame unit  110 . The lower frame  112  is formed in parallel to the upper frame  111  and forms a lower plate of the frame unit  110 . The supports  113  intervene between the upper and lower frames  111  and  112  such that constant distance therebetween is maintained. The upper frame  111  includes the support pulleys  114  which are supported by the support pulleys  101  of the head block  100  through the wires. The lower surface of the lower frame  111  faces a container  180  (refer to  FIG. 6 ). In this embodiment, it has been described that the lower frame  112  is a plate. However, the lower frame  112  may be a telescopic frame which may be expanded and contracted according to the size of the container  180 . 
         [0038]    The lower frame  112  includes a proximity sensor  150  and a vision camera  160  provided on the lower surface thereof. The proximity sensor  150  may sense whether or not a container is positioned in proximity to the lower frame  112 , and the vision camera  160  may detect the position of the container  180  by imaging a corner portion of the container  180 . Furthermore, the lower frame  112  includes fixation units  140  formed at four corners thereof, and the fixation units  140  are rotationally coupled to four corners of the container  180 . When the spreader is lowered by the trolley, the approximate position of the container  180  is first detected by the vision camera  160 . Based on the detection result, the position of the spreader is adjusted. After the spreader approaches the proximity of the container  180 , the proximity sensor  150  is used to detect whether the four corners of the container  180  is positioned in proximity to the proximity sensor. A process in which the position adjustment unit  130  is used to adjust the position of the frame unit  110 , based on the detection result of the proximity sensor  150 , will be described in connection with the position adjustment unit  130  which will be described below. 
         [0039]    Next, the attachment unit  120  will be described. The attachment unit  120  includes an attachment portion  121  and a shaft portion  122 . The attachment portion  121  is attached and fixed to the upper surface of the container, and the shaft portion  122  supports the attachment portion  121 , passes through a center housing  131  of the position adjustment unit  130  which will be described below, and extends to the through-hole  103  of the head block  100 . 
         [0040]    The attachment portion  121  may be formed of a magnet which may be attached to the upper surface of the container N formed of a metallic material by a magnetic force. Alternatively, the attachment portion  121  may be formed of a rubber absorption plate which may be attached by an adsorption force. Furthermore, when the attachment unit  120  is constructed by using a proper material having predetermined weight or more, it is possible to expect such an effect that the attachment portion  121  is substantially attached and fixed to the upper surface of the container by a frictional force which is generated by the weight of the attachment unit  120 . 
         [0041]    The shaft portion  122  may be formed in such a cylindrical shape as to rotatably support the attachment portion  121  with respect to the spreader S. The attachment portion  121  is fixed to the lower end of the shaft portion  122 . The shaft portion  122  passes through the center housing  131  of the position adjustment unit  130 . Therefore, when the center housing  131  is relatively moved with respect to the frame unit  110  by first and second horizontal movement portions of the position adjustment unit  130 , the shaft portion  122  is also relatively moved with respect to the frame unit  110  along the center housing  131 . 
         [0042]    Furthermore, the shaft portion  122  extends to the through-hole  130  of the head block  100 . The plurality of support, rollers  124  are fixed to the lower surface of the head block  100  along the circumference of the through-hole  103  through a jig. In such a structure, a vertical movement of the shaft  122  with respect to the head block  100  is allowed, but a horizontal movement thereof is limited. As a result, when the shaft portion  122  is relatively moved in the direction parallel to the frame unit  110  by the position adjustment unit  130 , the head block  100  confined by the shaft portion  122  is also moved in the parallel direction in the same manner as the shaft portion  122 . 
         [0043]    When the spreader is positioned in proximity of the container  180 , the attachment unit  120  having the above-described structure is advanced toward the upper surface of the container  180  from the spreader, and the attachment portion  121  of the attachment unit  120  is attached on the upper surface of the container  180 . The attachment portion  121  is substantially attached and fixed to the upper surface of the container  180 . Therefore, after the attachment portion  122  is fixed, the relative swaying motion between the spreader and the container  180  is significantly reduced even though the vessel pitches or rolls or the cable is swayed by the wind. 
         [0044]    Furthermore, since the attachment portion  121  is attached to the container  180 , the position adjustment unit  130  is driven to rotate and horizontally move the frame unit  110  on the basis of the attachment portion  121 . Then, the frame unit  110  may be aligned with the container  180 . 
         [0045]    Finally, the spreader is engaged with the container  180  by the fixation unit  140  which includes a twist locking mechanism  142  and flippers  141 . The twist locking mechanism  142  installed on a corner of the lower surface of the frame unit  110  is inserted into the corner casting  182  installed at the corner of the container  180 , to thereby prevent from rotationally deviating from the spreader. Then, the flippers  141  are engaged with the four corners of the container  180 . 
         [0046]      FIG. 5  illustrates the position adjustment unit  130  in accordance with the embodiment of the present invention. The position adjustment unit  130  includes the center housing  131  through which the shaft portion  122  passes, the first and second horizontal movement portions for transferring the center housing  131  in the horizontal direction, first second driving motors  1331  and  1332  for driving the first and second horizontal movement portions, respectively, and a third driving motor M for rotationally driving the shaft portion  122 . As illustrated in  FIG. 3 , the third driving motor M is fixed to the center housing  130 . But, the third driving motor M can be also fixed to the head block  100 . 
         [0047]    The first horizontal movement portion includes a first support rod  1342 , a first guide housing  13212 , and a first nut housing  13211 . The first support rod  1342  passes through the center housing  131  and is installed along the long-axis direction of the frame unit  110 . The first guide housing  13212  and the first nut housing  13211  are fixed to both ends of the first support rod  1342  to guide or transfer the first support rod  1342 . The first nut housing  13211  is installed on a first screw shaft  1351 . As the first screw shaft  1351  rotates in the clockwise or counterclockwise direction, the first nut housing  13211  is moved forward and backward along the short-axis direction of the frame unit  110 . When the first nut housing  13211  is moved forward and backward along the short-axis direction of the frame unit  110 , the first support rod  1342  fixed to the first nut housing  13211  is also moved forward and backward, and the center housing  131  through which the first support rod  1342  passes performs the same motion. The first guide housing  13212  fixed to an end of the first support rod  1342  guides the first support rod  1342  along a first guide rod  1352 . 
         [0048]    The second horizontal movement portion includes a second support rod  1341 , a second guide housing  13222 , and a second nut housing  13221 . The second support rod  1341  passes through the center housing  131  and is installed along the short-axis direction of the frame unit  110 . The second guide housing  13222  and the second nut housing  13221  are fixed to both ends of the second support rod  1341  to guide or transfer the second support rod  1341 . The second nut housing  13221  is installed on a second screw shaft  1353 . As the second screw shaft rotates in the clockwise or counterclockwise direction, the second nut housing  13221  is moved left and right along the long-axis direction of the frame unit  110 . When the second nut housing  13221  is moved left and right along the long-axis direction, the second support rod  1341  fixed to the second nut housing  13221  is also moved left and right, and the center housing  131  through which the second support rod  1341  passes performs the same motion. The second guide housing  13222  fixed to an end of the second support rod  1341  guides the second support rod  1341  along a second guide rod  1354 . 
         [0049]    The first and second support rods  1342  and  1341  may form a pair. 
         [0050]    The first and second driving motors  1331  and  1332  are connected to the first and second screw shafts  1351  and  1353 , respectively, through a belt, and transfer the center housing  131  in the horizontal direction. The third driving motor M is connected to the shaft portion  122  of the attachment unit  120  through a power transmission element such as a gear or belt and rotates the shaft portion  122 . When a rotational driving force is applied to the shaft portion  122  after the attachment unit  120  is fixed to the upper surface of the container, the frame  110  is rotated about the attachment unit  120 , because the shaft portion  122  is not rotated. 
         [0051]      FIGS. 6 and 7  show a process in which the frame unit  110  of the spreader is aligned with the container  180  by the attachment unit  120  and the position adjustment unit  130 .  FIG. 6  illustrates a situation in which the attachment portion  121  of the attachment unit  120  is attached and fixed to a position which is slightly deviated from the center of the container in a state in which the attachment portion  121  is slightly rotated. At this time, the proximity sensor  150  is used to acquire the relative positional relation of the frame unit  110  with respect to the container  180 . Based on the result, a movement path of the frame unit  110  is determined, and the first and second driving motors  1331  and  1332  are driven to move the frame unit  110  to the center of the container. Furthermore, the third driving motor M is driven to rotate the frame unit  110 . As such, the proximity sensor  150  is used to detect the position and posture of the frame unit  110 , and the first to third driving motors  1331 ,  1332 , and M are driven on the basis of the detection result. Then, the frame unit  110  may be aligned with the container  180 . 
         [0052]      FIG. 8  depicts a method for precisely controlling the position of the head block  100  by adjusting the relative position between the head block  100  and the frame unit  110  through the position adjustment unit  130 . Referring to  FIG. 8 , when the position adjustment unit  130  is driven in a state in which the horizontal direction movement of the frame unit  110  is restricted, for example, a state in which the spreader is fixed to the container and the container is not yet lifted but placed on the bottom, the frame unit  110  is fixed, but the head block  100  is relatively moved with respect to the frame unit  110 . In  FIG. 8 , a solid line indicates a state in which the head block  100  is moved in the left direction from the center by the position adjustment unit  130 , and a dashed dot line indicates a state in which the head block  100  is moved in the right direction from the center by the position adjustment unit  130 . In order for the movement of the head block  100 , the fixation of the attachment unit  120  to the upper surface of the container needs to be released. Such a horizontal movement of the head block  100  may precisely position the head block  100  at a desired location. 
         [0053]      FIG. 8  illustrates a case in which, when the frame unit  110  is fixed, the position adjustment unit  130  is driven to transfer the head block  100 . On the other hand,  FIG. 9  illustrates a case in which, when the horizontal position of the head block  100  is fixed, for example, when the spreader is lifted by the trolley, the position adjustment unit  130  is driven to move the frame unit  110  in the left and right, direction. As such, when the container is fixed and coupled to the spreader and then lifted by the trolley and the position adjustment unit  130  is driven to minutely adjust the position of the frame unit  110 , the position of the container attached to the frame unit  110  may be precisely controlled. 
         [0054]    In case that the position adjustment unit  130  is driven before the landing of the spreader onto the container, the position of the frame unit  110  can be minutely adjusted. As a result, the position of the frame unit  110  can be precisely controlled and aligned with the container. Then, the frame unit  110  lands on the container. In accordance with the crane spreader and the method for automatically landing the same, the spreader which is swayed by various external factors on the ground or the sea, for example, a mobile harbor may be quickly and accurately fixed to a container by the attachment unit of the spreader fixed to the container and the position adjustment unit for adjusting the position and posture of the frame unit on the basis of the attachment unit, and then transferred stably. 
         [0055]    Further, even after the frame unit is coupled to the container, the head block is relatively moved with respect to the frame unit, or the frame unit is relatively moved with respect to the head block, thereby precisely controlling the position of the container coupled to the frame or the head block. 
         [0056]    While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.