Technical Field

[1] The present invention relates to a robot having a rotatable arm, and more particularly, to a robot which can perform a blasting or painting work inside a ship when the ship is manufactured. Background Art

[2] When the bottom or side hull of a ship is damaged, a double hull structure can prevent water from entering the ship. Further, the double hull structure can enhance the strength of the bottom hull and increase space availability. Further, since the center of gravity of the ship is lowered, the stability of the ship is improved.

[3] Because of such advantages of the double hull structure, demand on ships having a double hull structure is increasing recently. However, because the bottom hull of the double hull structure has a complex frame structure, there are difficulties in automating the manufacturing process.

[4] FIG. 1 is a perspective view of an inner bottom block constituting a double hull structure.

[5] As shown in FIG. 1, the inner bottom block 1 constituting a double hull structure has a structure in which a plurality of longis 2 having a T-shaped cross-section are welded on a bottom plate 3 formed of a wide steel plate and are installed in parallel to each other so as to be spaced at a predetermined interval from each other. Further, a web floor 5 and a girder 4 which are formed of a steel plate are installed vertically on the bottom plate 3.

[6] In general, when the inner bottom block 1 is manufactured, the bottom plate 3, the longis 2, the web floors 5, and the girder 4 are provisionally welded so as to form the entire shape, first. Then, a main welding work is performed. Conventionally, the welding process has been performed while an automatic welding device is moved by a crane.

[7] FIG. 2 is a perspective view of a double bottom block in which an upper plate is coupled to the inner bottom block shown in FIG. IA.

[8] As shown in FIG. 2, the upper and lower surfaces and the left and right side surfaces of the double bottom block 8 are closed. Therefore, a crane cannot be used for the double bottom block 8. At present, a worker enters the double bottom block 8 and performs a welding work manually.

[9] However, since it is very dark inside the double bottom block 8 and the work is performed in the closed space, the work environment is very poor because of gas produced during the welding work.

[10] Meanwhile, when the double hull structure is manufactured, a grinding, blasting, or painting work should be performed, in addition to the welding work for the inner bottom block 1.

[11] Conventionally, various equipments required for such works were put into the inner bottom block 1 by a crane. And, because the equipments cannot be put into the double bottom block 8 by a crane, a worker had to enter the double bottom block 8 and perform various works manually. However, since the work environment is very poor because of dust, gas and odor produced during grinding, blasting, and painting works, such work may easily harm the worker's health.

[12] Recently, in order to solve such a problem, a robot has been developed, which can perform grinding, blasting, and painting works inside the double bottom block 8 not only for the inner bottom block 1.

[13] In particular, when a blasting work is performed as a pretreatment work, the work should be performed on the entire area of high-rising structures such as the web floor 5 and the girder 4 inside the inner bottom block 1 or the double bottom bloc k 8. Therefore, there is a demand for a robot which has a wide operation range without interfering with structures. Disclosure of Invention

Technical Problem

[14] The present invention has been made in view of the above problems, and it is an object of the present invention to provide a robot, which has a wide operation range in a space in which obstacles are installed, such as a double hull structure, without interfering with obstacles. Technical Solution

[15] In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a robot comprising: a transfer unit positioned in a horizontal direction over a plurality of obstacles arranged in parallel to each other; a first arm that is installed on the transfer unit so as to ascend or descend in a vertical direction; and a second arm installed on the first arm rotatably and extensibly. The rotation axis of the second arm is perpendicular to both the horizontal and vertical directions.

[16] In an embodiment of the present invention, the first arm may include a vertical plate fixed to the transfer unit; a first arm body extending in the vertical direction and coupled to the vertical plate so as to ascend or descend; and a first arm elevating motor for lifting or lowering the first arm body.

[17] The first arm may further include a driving sprocket rotatably installed at the upper end of the first arm body; a driven sprocket rotatably installed at the lower end of the first arm body; and a chain wound around the driving sprocket and the driven sprocket. The driving sprocket is connected to the first arm elevating motor, and one side of the chain is connected to the vertical plate.

[18] In an embodiment of the present invention, the second arm may include a second arm body vertically extending in parallel to the first arm; a rotation motor fixed to the first arm and connected to the second arm body so as to rotate the second arm body; and a second arm elevating motor for lifting or lowering the second arm body.

[19] The second arm may further include an elevating plate coupled to the rear surface of the second arm body so as to move linearly with respect to the second arm. As the rotation motor is connected to the elevating plate and rotates the elevating plate, the second arm body is rotated along with the elevating plate.

[20] The second arm may further include a rack installed on the second arm body so as to extend in a length direction of the second arm body; and a pinion engaged with the rack and rotated by the second arm elevating motor. The second arm elevating motor is fixed to the elevating plate.

[21] In an embodiment of the present invention, the robot may further comprise an extensible arm that is installed on the second arm so as to extend or retract.

[22] The second arm may further include a chain installed so as to enclose the front and rear surfaces of the second arm body along the length direction of the second arm body. The extensible arm is coupled to a portion of the chain which is positioned at the front surface of the second arm body, and the elevating plate is coupled to a portion of the chain which is positioned at the rear surface of the second arm body.

Advantageous Effects

[23] According to the present invention, because the second arm is connected so as to rotate about the first arm and to extend or retract in a work space such as a double hull structure where obstacles are provided, the robot can have a wide operation range without interference with the obstacles when performing a blasting or painting work. Brief Description of Drawings

[24] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[25] FIG. 1 is a perspective view of an inner bottom block constituting a double hull structure;

[26] FIG. 2 is a perspective view of a double bottom block constituting a double hull structure;

[27] FIG. 3 is a front perspective view of a robot according to the present invention; [28] FIG. 4 is a rear perspective view of a first arm, showing a state where the first arm is partially disassembled;

[29] FIG. 5 is a rear perspective view of a second arm;

[30] FIG. 6 is a perspective view of the second arm, showing a state where the second arm is partially disassembled;

[31] FIG. 7 is a side cross-sectional view of the second arm; and

[32] FIGS. 8 through 11 are diagrams sequentially showing the operation of the robot according to the invention. Best Mode for Carrying out the Invention

[33] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[34] As shown in FIG. 3, a robot having a rotatable arm according to the invention has a transfer unit 100 which is disposed over a plurality of longis 2a and 2b, a first arm 10 which is installed on the transfer unit 100 so as to move linearly and to ascend or descend, and a second arm 20 which is rotatably installed on the first arm 10 so as to extend or retract. The second arm 20 has a multi-joint manipulator 50 connected to an end thereof, the multi-joint manipulator 50 being provided for a blasting or painting work.

[35] The transfer unit 100 has a lower body 110 disposed on the plurality of longis 2a and

2b and an upper body 120 which is installed on the lower body 110 so as to move linearly in a horizontal direction (X-axis direction). As the upper body 120 and the lower body 110 move linearly along the horizontal direction with respect to each other, the entire transfer unit 100 is moved in the horizontal direction across the longis 2a and 2b. Because the relative motion between the upper and lower bodies 120 and 110 can be achieved by a general linear motion system, the descriptions thereof will be omitted.

[36] The first arm 10 is coupled to the upper body 120 so as to move linearly in the horizontal direction and to ascend or descend in the vertical direction (Z-axis direction). Specifically, the upper body 120 has a base plate 121 installed on the top surface thereof such that the base plate 121 can move linearly in the horizontal direction. The first arm 10 is coupled to the base plate 121 so as to ascend or descend.

[37] Although not shown in the drawing, the base plate 121 is moved linearly on the upper body 120 as a motor 122 is driven by a power transmission system well known to those skilled in the art, such as a power transmission system using a rack and a pinion or a power transmission system using a ball screw and a ball nut.

[38] As shown in FIG. 4, the first arm 10 has a vertical plate 13 which is coupled to a side surface of the base plate 121, a first arm body 11 which extends in the vertical direction and is coupled so as to move linearly (ascend or descend) with respect to the vertical plate 13, and a first arm elevating motor 15 which moves linearly the first arm body 11 with respect to the vertical plate 13.

[39] The first arm body 11 has a driving sprocket 16 and a driven sprocket 17 installed at the upper and lower ends thereof, respectively. Around the driving and driven sprockets 16 and 17, a chain 18 is wound. The driving sprocket 16 is driven by the first arm elevating motor 15 connected thereto. The vertical plate 13 is connected at one side of the chain 18.

[40] When the driving sprocket 16 is rotated by the first arm elevating motor 15, the chain

18 is moved in the vertical direction. At this time, since the vertical plate 13 connected at the side of the chain 18 is fixed to the transfer unit 100 through the base plate 121, the first arm body 11 is lifted or lowered in the vertical direction.

[41] To guide a smooth relative motion between the first arm body 11 and the vertical plate 13, a guide rail 19 is installed in the first arm body 11, and a guide block (not shown) which is coupled to the guide rail 19 is installed in the vertical plate 13.

[42] As shown in FIG. 5, the second arm 20 has a second arm body 21 which extends in the vertical direction, a rotation motor 22 which rotates the second arm body 21 about a direction (Y-axis direction) perpendicular to the horizontal and vertical directions, respectively, and a second arm elevating motor 23 which lifts or lowers the second arm body 21 with respect to the first arm 10.

[43] The second arm body 21 has an elevating plate 25 installed on the rear surface thereof (facing the first arm) such that the elevating plate 25 can move linearly along the second arm body 21. The rotation motor 22 is connected to the elevating plate 25 via a decelerator 24, and the decelerator 24 is coupled to the upper end of the first arm 10. That is, the rotation motor 22 is fixed to the first arm 10 via the decelerator 24.

[44] As such, when the rotation motor 22 is driven, the rotation driving force of the rotation motor 22 is transmitted to the elevating plate 25 through the decelerator 24 such that the elevating plate 25 is rotated about the rotation motor 25, because the rotation motor 22 is fixed to the first arm 10. Accordingly, the second arm body 21 is rotated, too. That is, as the rotation motor 22 is driven, the second arm 20 is rotated about the first arm 10, with the Y-axis direction as the rotation axis.

[45] Meanwhile, the second arm elevating motor 23 is fixed to the elevating plate 25.

When the rotation motor 22 is driven, the second arm elevating motor 23 is rotated along with the elevating plate 25.

[46] As shown in FIG. 6, the second arm body 21 has a rack 41 which is installed so as to extend along the length direction of the second arm body 21, and the second arm elevating motor 23 is connected to a pinion 42 engaged with the rack 41. Therefore, when the second arm elevating motor 23 is driven, the rack 41 is rotated so as to move the pinion 42 in the vertical direction. Accordingly, the whole of the second arm 20 moves linearly (lifted and lowered) with respect to the first arm 10.

[47] The robot according to this embodiment also has an extensible arm 30 which is installed on the second arm 20 so as to extend or retract.

[48] The extensible arm 30 extends or retracts from the second arm 20, as the second arm elevating motor 23 is driven. To this end, the second arm body 21 has two sprockets 43 installed at the upper and lower ends thereof, respectively, so as to be spaced with a predetermined interval from each other. Two chains 45 are coupled to the sprockets 43 so as to enclose the front and rear surfaces of the second arm body 21 in the length direction of the second arm body 21.

[49] As shown in FIG. 7, the elevating plate 25 is coupled to a portion of the chain 45 which is positioned at the rear surface of the second arm body 21, and the extensible arm 30 is coupled to a portion of the chain 45 which is positioned at the front surface of the second arm body 21.

[50] When the second arm body 21 is lifted or lowered by the second arm elevating motor

23, an effect occurs by which the elevating plate 25 moves linearly in a direction opposite to the second arm body 21. Therefore, the power of the second arm elevating motor 22 is transmitted to the chain 45 via the elevating plate 25 and the chain 45 rotates around the sprockets 43. Then, the extensible arm 30 in the opposite side of the elevating plate 25 extends or retracts while being lifted or lowered with respect to the second arm 20.

[51] As a result, when the second arm elevating motor 23 is driven, the second arm 20 is lifted or lowered, and simultaneously, the extensible arm 30 extends or retracts with respect to the second arm 20.

[52] In this embodiment, the manipulator 50 is installed at the end of the extensible arm

30 and is constructed so as to have three-axis joints. However, the construction of the manipulator 50 is not limited thereto, and the manipulator 50 may have a larger number of joints, if necessary.

[53] Hereinafter, referring to FIGS. 8 through 11, the expanding and contracting operation and the rotating operation of the arms of the robot according to the invention will be described.

[54] First, when a blasting or painting work is performed in a region below the longis 2a and 2b in a state where the robot is disposed over the longis 2a and 2b, the first arm 10 is lowered by the first arm elevating motor 15 so as to position the manipulator 50 at a work position, as shown in FIG. 3.

[55] Next, when a blasting or painting work is performed in a region above the longis 2a and 2b, the first arm 10 is lifted above the transfer unit 100 as much as possible by the first arm elevating motor 15, as shown in FIG. 8.

[56] Then, as shown in FIGS. 9 and 10, when the second arm 10 is rotated 180 degrees about the rotation motor 22 by the rotation motor 22, the manipulator 50 is directed to the upper side of the longis 2a and 2b.

[57] After that, when the second arm elevating motor 23 is driven, the second arm 20 is lifted so as to extend from the first arm 10, and simultaneously, the extensible arm 30 extends from the second arm 30, as shown in FIG. 11. Then, the manipulator 50 is lifted at the maximum height. Therefore, a blasting or painting work can be performed at a high position above the longis 2a and 2b.

[58] According to this embodiment, the upper and lower positions of the manipulator 50 are changed while the second arm 20 rotates about the first arm 10, and the second arm 20 extends or retracts while being lifted or lowered with respect to the first arm 10. Therefore, it is possible to perform a blasting or painting work smoothly without any interference with neighboring structures within a confined space. Industrial Applicability

[59] The present invention can be used for manufacturing a ship having a double hull structure.

[60] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.