WO2009061101A2

WO2009061101A2 - Articulating type electric jib crane

Info

Publication number: WO2009061101A2
Application number: PCT/KR2008/006421
Authority: WO
Inventors: Sung-Goo Kim
Original assignee: Kg Inc.
Priority date: 2007-11-05
Filing date: 2008-10-30
Publication date: 2009-05-14
Also published as: KR100891469B1; WO2009061101A3

Abstract

An articulating type electric jib crane is constructed in a structure in which jibs (2, 4), constituting a plurality of articulated joints, are connected to a jib post (1), automatic rotary units (10, 30), controllable by a controller (80), are mounted at the respective jibs (2, 4) to rotate the respective jibs (2, 4), and a hoist (50) is mounted at an end of the outermost jib (4) to raise and lower a weight. According to the present invention, it is possible to control the rotational operations and rotational angles of the jibs (2, 4) and to prevent the jibs (2, 4) from colliding with an obstacle. Also, the articulating type electric jib crane can be mounted and used in a clean room.

Description

ARTICULATING TYPE ELECTRIC JIB CRANE

Technical Field

[1] The present invention relates to an articulating type electric jib crane, and, more particularly, to an articulating type electric jib crane that is capable of repeatedly pulling up and conveying weights at sites where the convenience of the weights is repeatedly and frequently carried out, at sites having small spaces, or at sites where one or more obstacles exist. Background Art

[2] Generally, a jib crane is a crane having one or more jibs. Also, the jib crane is also referred to as a rotary crane because the jib crane is configured to rotate. The jib crane is normally used to convey small-sized objects. In particular, the jib crane is principally used to periodically and repeatedly pull up and convey weights at sites where it is difficult to use an overhead traveling crane or a large-sized cargo crane. Also, the jib crane is fixedly mounted and used at a facility that handles weights.

[3] The jib crane includes a stationary shaft, a rotary shaft rotatably mounted at the upper end of the stationary shaft, a jib having one end coupled to the upper end of the rotary shaft such that the jib can be rotated with the rotary shaft, and a hoist mounted at the other end of the jib to pull up a weight.

[4] In such a conventional jib crane, the route for weight conveyance is restricted. That is, the weight pulled up by the hoist is conveyed in the horizontal direction along a circle having the jib as the radius thereof. Consequently, when another facility or an obstacle is located within the rotational radius of the conventional jib crane, the rotational operation of the jib is disturbed. If the jib crane is carelessly or unintentionally rotated in this state, the jib, the hoist, and/or the weight may collide with the facility or obstacle, with the result that the jib crane may be damaged or broken, or a safety- related accident may occur.

[5] The conventional jib crane has another problem in that only a single jib is provided, and therefore, the place where the weight is pulled up or the place where the weight is pulled down is restricted to a single point of a circle formed by the rotation radius of the jib.

[6] That is, when the weight is pulled up or pulled down by the conventional jib crane, it is required that the position where the weight is to be pulled up or the position where the weight is to be pulled down be located on a circle along which the hoist is rotated.

[7] If the position where the weight is to be pulled up is not located on the circle along which the hoist is rotated, it is necessary to move the weight, manually or using other equipment, such that the weight is located on the circle. Similarly, if the position where the weight is to be pulled down is not located on the circle along which the hoist is rotated, it is necessary to convey the weight to a final position manually or using other equipment after pulling down the weight.

[8] Consequently, it is necessary for a worker to manually transfer the weight to a working range of the jib crane or to manually transfer the pulled-down weight to the final position, with the result that, the working time increases, and the working efficiency lowers. Disclosure of Invention Technical Problem

[9] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an articulating type electric jib crane that is capable of controlling the rotation radius of jibs.

[10] It is another object of the present invention to provide an articulating type electric jib crane that is capable of automatically controlling the rotational operations and rotation angles of the jibs.

[11] It is another object of the present invention to provide an articulating type electric jib crane that is capable of preventing the jibs from colliding with an obstacle.

[12] It is yet another object of the present invention to provide an articulating type electric jib crane that can be mounted and used in a clean room. Technical Solution

[13] In accordance with the present invention, the above and other objects can be accomplished by the provision of an articulating type electric jib crane constructed in a structure in which jibs, constituting a plurality of articulated joints, are connected to a jib post, automatic rotary units, controllable by a controller, are mounted at the respective jibs to rotate the respective jibs, and a hoist is mounted at an end of the outermost jib to raise and lower a weight.

[14] Preferably, the articulating type electric jib crane includes a jib post, a first jib mounted at the upper part of the jib post, a first automatic rotary unit mounted at the jib post and the first jib to rotate the first jib, a second jib mounted at a free end of the first jib, a second automatic rotary unit mounted at the first jib and the second jib to rotate the second jib, a hoist mounted at one free end of the second jib to pull up a weight, and a controller connected to the first automatic rotary unit and the second automatic rotary unit to control the first automatic rotary unit and the second automatic rotary unit.

[15] Preferably, the first automatic rotary unit includes a first rotary shaft mounted at the upper part of the jib post, a first rotary shaft support part mounted at the first rotary shaft and the jib post to rotatably support the first rotary shaft, and a first worm speed reducer mounted in the first rotary shaft support part, while being connected to the controller, to rotate the first rotary shaft. Also, the second automatic rotary unit includes a second rotary shaft mounted at the other free end of the second jib, a second rotary shaft support part mounted at the first rotary shaft and the second rotary shaft to rotatably support the second rotary shaft, and a second worm speed reducer mounted in the second rotary shaft support part, while being connected to the controller, to rotate the second rotary shaft.

[16] Preferably, the first rotary shaft support part includes a first lower housing mounted at the lower part of the first rotary shaft, a first lower bearing mounted in the first lower housing to support the rotation of the first rotary shaft, a first worm speed reducer box mounted at the upper part of the first lower housing such that the first worm speed reducer is mounted in the first worm speed reducer box, a first upper housing mounted at the upper part of the first worm speed reducer box to support the upper part of the first rotary shaft, and a first upper bearing mounted in the first upper housing to support the rotation of the first rotary shaft. Also, the second rotary shaft support part includes a second lower housing mounted at the lower part of the second rotary shaft, a second lower bearing mounted in the second lower housing to support the rotation of the second rotary shaft, a second worm speed reducer box mounted at the upper part of the second lower housing such that the second worm speed reducer is mounted in the second worm speed reducer box, a second upper housing mounted at the upper part of the second worm speed reducer box to support the upper part of the second rotary shaft, and a second upper bearing mounted in the second upper housing to support the rotation of the second rotary shaft.

[17] Preferably, the first worm speed reducer includes a first worm wheel coupled to the first rotary shaft such that the first worm wheel can be rotated with the first rotary shaft, a first worm engaged with the first worm wheel to transmit power to the first worm wheel, and a first drive motor connected to the first worm to transmit power to the first worm, the first drive motor being also connected to the controller such that the first drive motor can be controlled by the controller. Also, the second worm speed reducer includes a second worm wheel coupled to the second rotary shaft such that the second worm wheel can be rotated with the second rotary shaft, a second worm engaged with the second worm wheel to transmit power to the second worm wheel, and a second drive motor connected to the second worm to transmit power to the second worm, the second drive motor being also connected to the controller such that the second drive motor can be controlled by the controller.

[18] Preferably, the first jib is provided with a first sensor connected to the controller, such that the first sensor can be controlled by the controller, to restrict the rotational angle of the first jib and to prevent the collision of the first jib at the time of rotating the first jib. Also, the second jib is provided with a second sensor connected to the controller, such that the second sensor can be controlled by the controller, to restrict the rotational angle of the second jib and to prevent the collision of the second jib at the time of rotating the second jib.

[19] Preferably, the first jib has cable holes formed therein.

[20] Preferably, a bellows pipe is further provided to cover a chain between the lower part of a main body of the hoist and a hook of the hoist to prevent dust generated during the winding and unwinding movement of the chain from scattering to the circumference, the upper end of the bellows pipe being coupled to the bottom of the main body by a first clamp, the lower end of the bellows pipe being coupled to the upper part of the hook by a second clamp.

[21] Preferably, the first clamp includes a fixing part supported at the main body of the hoist, a pair of first fastening pieces configured to correspond to the upper end circumference of the bellows pipe, one end of each of the first fastening pieces being fixed to a corresponding end of the fixing part, the other end of each of the first fastening pieces being fixed to the main body, a pair of second fastening pieces coupled to the corresponding first fastening pieces to fix the upper end of the bellows pipe, and fastening bolts to fasten the first fastening pieces and the second fastening pieces to each other.

[22] Preferably, the second clamp includes a lower plate located at the lower end of the bellows pipe, a pair of fastening pieces coupled to the lower plate to fix the lower end of the bellows pipe, and fastening bolts to fasten the lower plate and the fastening pieces to each other.

Advantageous Effects

[23] According to the present invention with the above-stated construction, the jibs constitute a plurality of articulated joints, and therefore, it is possible to relatively freely control the rotation radius of the hoist. Consequently, it is possible to pull up a weight even when the weight is located over a wide range.

[24] Also, the first jib and the second jib are automatically rotated by the first automatic rotary unit and the second automatic rotary unit, and the first automatic rotary unit and the second automatic rotary unit are controlled by the controller. Consequently, it is possible to automatically control the rotational operations and rotational angles of the first jib and the second jib through the use of the first automatic rotary unit, the second automatic rotary unit, and the controller.

[25] Also, the first sensor and the second sensor, which are connected to the controller, are mounted at the first jib and the second jib to prevent the first jib and the second jib from colliding with an obstacle at the time of rotating the first jib and the second jib. Consequently, the first jib and the second jib do not collide with the obstacle even when the obstacle is located within rotational ranges of the first jib and the second jib, and therefore, it is possible to prevent the damage to parts of the articulating type electric jib crane and the occurrence of a safety-related accident.

[26] Furthermore, the bellows pipe is mounted around the chain by the first clamp and the second clamp to prevent dust generated during the winding and unwinding movement of the chain of the hoist from scattering to the circumference. Also, the respective parts of the articulating type electric jib crane are coated with an antistatic paint. Consequently, the articulating type electric jib crane according to the present invention maximally prevents the generation and scattering of dust, whereby the articulating type electric jib crane can be mounted and used in a clean room. Brief Description of the Drawings

[27] 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:

[28] FIG. 1 is a partially exploded front view schematically illustrating an articulating type electric jib crane according to the present invention;

[29] FIG. 2 is a partially enlarged front view schematically illustrating a first rotary shaft;

[30] FIG. 3 is a partially enlarged front view schematically illustrating a second rotary shaft;

[31] FIG. 4 is a front view schematically illustrating the sections of the first rotary shaft and the second rotary shaft;

[32] FIG. 5 is a partially enlarged sectional view of the first rotary shaft;

[33] FIG. 6 is a partially enlarged sectional view of the second rotary shaft;

[34] FIG. 7 is a plan view schematically illustrating the use state of the articulating type electric jib crane according to the present invention;

[35] FIG. 8 is a perspective view schematically illustrating a first clamp;

[36] FIG. 9 is a perspective view schematically illustrating the bottom of the first clamp;

[37] FIG. 10 is an exploded perspective view of the first clamp;

[38] FIG. 11 is a perspective view schematically illustrating a second clamp; and

[39] FIG. 12 is an exploded perspective view of the second clamp.

Best Mode for Carrying Out the Invention

[40] Now, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[41] FIG. 1 is a partially exploded front view schematically illustrating an articulating type electric jib crane according to the present invention, FIG. 2 is a partially enlarged front view schematically illustrating a first rotary shaft 11, and FIG. 3 is a partially enlarged front view schematically illustrating a second rotary shaft 31. FIG. 4 is a front view schematically illustrating the sections of the first rotary shaft 11 and the second rotary shaft 31, FIG. 5 is a partially enlarged sectional view of the first rotary shaft 11, and FIG. 6 is a partially enlarged sectional view of the second rotary shaft 31. FIG. 7 is a plan view schematically illustrating the use state of the articulating type electric jib crane according to the present invention, FIG. 8 is a perspective view schematically illustrating a first clamp 60, and FIG. 9 is a perspective view schematically illustrating the bottom of the first clamp 60. FIG. 10 is an exploded perspective view of the first clamp 60, FIG. 11 is a perspective view schematically illustrating a second clamp 70, and FIG. 12 is an exploded perspective view of the second clamp 70.

[42] As shown in FIGS. 1 and 4, the articulating type electric jib crane according to the present invention is constructed in a structure in which a first jib 2 and a second jib 4, constituting a plurality of articulated joints, are connected to a jib post 1 , the first jib 2 and the second jib 4 are provided with a first automatic rotary unit 10 and a second automatic rotary unit 30 which are controlled, by a controller 80, to rotate the first jib 2 and the second jib 4, respectively, and a hoist 50 is mounted at the end of the second jib 4 to raise and lower a weight.

[43] Hereinafter, the articulating type electric jib crane according to the present invention will be described in more detail.

[44] The jib post 1 is fixed to the ground or a facility from which a weight will be pulled up. The first jib 2 is mounted at the upper part of the jib post 1.

[45] At opposite sides of the first jib 2 are formed cable holes 2a through which a cable 6 extending from the controller 80 to the upper part of a first rotary shaft 11 is disposed in the first jib 2. Consequently, the cable 6, connected between the first automatic rotary unit 10 and the second automatic rotary unit 30, is inserted through the cable hole 2a formed at one side of the first jib 2 and is then withdrawn through the cable hole 2a formed at the other side of the first jib 2. As a result, a major portion of the cable 6 extending along the first jib 2 is not exposed to the outside but is neatly disposed in the first jib 2.

[46] The first automatic rotary unit 10 is mounted to the jib post 1 and the first jib 2 to rotate the first jib 2.

[47] As shown in detail in FIGS. 2 and 5, the first automatic rotary unit 10 includes the first rotary shaft 11 mounted at the upper part of the jib post 1, a first rotary shaft support part 12 mounted at the first rotary shaft 11 and the jib post 1 to rotatably support the first rotary shaft 11, and a first worm speed reducer 18 mounted in the first rotary shaft support part 12, while being connected to the controller 80, to rotate the first rotary shaft 11. [48] The first rotary shaft support part 12 includes a first lower housing 13 mounted at the lower part of the first rotary shaft 11, a first lower bearing 14 mounted in the first lower housing 13 to support the rotation of the first rotary shaft 11, a first worm speed reducer box 15 mounted at the upper part of the first lower housing 13 such that the first worm speed reducer 18 is mounted in the first worm speed reducer box 15, a first upper housing 16 mounted at the upper part of the first worm speed reducer box 15 to support the upper part of the first rotary shaft 11, and a first upper bearing 17 mounted in the first upper housing 16 to support the rotation of the first rotary shaft 11.

[49] The first worm speed reducer 18 includes a first worm wheel 19 coupled to the first rotary shaft 11 such that the first worm wheel 19 can be rotated with the first rotary shaft 11, a first worm 20 engaged with the first worm wheel 19 to transmit power to the first worm wheel 19, and a first drive motor 21 connected to the first worm 20 to transmit power to the first worm 20, the first drive motor 21 being also connected to the controller 80 such that the first drive motor 21 can be controlled by the controller 80.

[50] The second jib 4 is mounted at the free end of the first jib 2. As shown in detail in

FIGS. 3 and 6, the second automatic rotary unit 30 is mounted at the second jib 4 to rotate the second jib 4.

[51] The second automatic rotary unit 30 includes the second rotary shaft 31 mounted at the free end of the second jib 4, a second rotary shaft support part 12 mounted at the first rotary shaft 11 and the second rotary shaft 31 to rotatably support the second rotary shaft 31, and a second worm speed reducer 38 mounted in the second rotary shaft support part 32, while being connected to the controller 80, to rotate the second rotary shaft 31.

[52] The second rotary shaft support part 32 includes a second lower housing 33 mounted at the lower part of the second rotary shaft 31, a second lower bearing 34 mounted in the second lower housing 33 to support the rotation of the second rotary shaft 31, a second worm speed reducer box 35 mounted at the upper part of the second lower housing 33 such that the second worm speed reducer 38 is mounted in the second worm speed reducer box 35, a second upper housing 36 mounted at the upper part of the second worm speed reducer box 35 to support the upper part of the second rotary shaft 31, and a second upper bearing 37 mounted in the second upper housing 36 to support the rotation of the second rotary shaft 31.

[53] The second worm speed reducer 38 includes a second worm wheel 39 coupled to the second rotary shaft 31 such that the second worm wheel 39 can be rotated with the second rotary shaft 31, a second worm 40 engaged with the second worm wheel 39 to transmit power to the second worm wheel 39, and a second drive motor 41 connected to the second worm 40 to transmit power to the second worm 40, the second drive motor 41 being also connected to the controller 80 such that the second drive motor 41 can be controlled by the controller 80.

[54] Meanwhile, the first jib 2 is provided with a first sensor 3 which is connected to the controller 80, such that the first sensor 3 can be controlled by the controller 80, to restrict the rotational angle of the first jib 2 and to prevent the collision of the first jib 2 at the time of rotating the first jib 2. Similarly, the second jib 4 is provided with a second sensor 5 which is connected to the controller 80, such that the second sensor 5 can be controlled by the controller 80, to restrict the rotational angle of the second jib 4 and to prevent the collision of the second jib 4 at the time of rotating the second jib 4. Consequently, even when an obstacle is located within rotational ranges of the first jib 2 and the second jib 4, it is possible to prevent the first jib 2 and the second jib 4 from colliding with the obstacle, thereby preventing the damage to parts of the articulating type electric jib crane and the occurrence of a safety-related accident.

[55] The hoist 50 is mounted at the free end of the second jib 4 to pull up a weight. As shown in FIGS. 1, 4, and 8 to 12, a bellows pipe 55 covers a chain 53 between the lower part of a main body 51 of the hoist 50 and a hook 52 of the hoist 50 to prevent dust generated during the winding and unwinding movement of the chain 53 from scattering to the circumference. The upper end of the bellows pipe 55 is coupled to the bottom of the main body 51 by a first clamp 60, and the lower end of the bellows pipe 55 is coupled to the upper part of the hook 52 by a second clamp 70.

[56] The first clamp 60 includes a fixing part 61 supported at the main body 51 of the hoist 50, a pair of first fastening pieces 62 configured to correspond to the upper end circumference of the bellows pipe 55, one end of each of the first fastening pieces 62 being fixed to a corresponding end of the fixing part 61, the other end of each of the first fastening pieces 62 being fixed to the main body 51 of the bellows pipe 55, a pair of second fastening pieces 63 coupled to the corresponding first fastening pieces 62 to fix the upper end of the bellows pipe 55, and fastening bolts 64 to fasten the first fastening pieces 62 and the second fastening pieces 63 to each other.

[57] The second clamp 70 includes a lower plate 71 located at the lower end of the bellows pipe 55, a pair of fastening pieces 72 coupled to the lower plate 71 to fix the lower end of the bellows pipe 55, and fastening bolts 73 to fasten the lower plate 71 and the fastening pieces 72 to each other.

[58] Unexplained reference numeral 54 indicates a chain box to receive the chain 53.

[59] In the articulating type electric jib crane with the above-stated construction according to the present invention, the jib post 1, the first jib 2, the second jib 4, and the main body 51, the hook 52, the chain 53, and the chain box 54 of the hoist 50 are coated with an antistatic paint. Consequently, the articulating type electric jib crane according to the present invention maximally prevents the generation and scattering of dust. For this reason, the articulating type electric jib crane according to the present invention can be mounted and used in a clean room.

[60] The first automatic rotary unit 10 and the second automatic rotary unit 30 are connected to the controller 80, which controls the first automatic rotary unit 10 and the second automatic rotary unit 30. A remote control 81 is electrically connected to the controller 80. Consequently, it is possible to control the rotational speed, rotational angle, and on/off of the first automatic rotary unit 10 and the second automatic rotary unit 30 through the use of the remote control 81.

[61] In the articulating type electric jib crane with the above-stated construction according to the present invention, it is possible to control the rotating operation of the first jib 2 and the second jib 4, as shown in FIG. 7, by directly manipulating the controller 80 or by remotely manipulating the controller 80 through the use of the remote control 81. That is, when the first drive motor 21 of the first worm speed reducer 18 is operated, the first worm 20 and the first worm wheel 19 are also operated together, with the result that the first rotary shaft 11 and the first jib 2 fixed to the first rotary shaft 11 are rotated. Also, when the second drive motor 41 of the second worm speed reducer 38 is operated, the second worm 40 and the second worm wheel 39 are also operated together, with the result that the second rotary shaft 31 and the second jib 4 fixed to the second rotary shaft 31 are rotated.

[62] The articulating type electric jib crane according to the present invention, which is operated as described above, has the following advantages.

[63] First, the first jib 2 and the second jib 4 constitute a plurality of articulated joints, and therefore, it is possible to relatively freely control the rotation radius of the hoist 50. Consequently, it is possible to pull up a weight even when the weight is located over a wide range.

[64] Second, the first jib 2 and the second jib 4 are automatically rotated by the first automatic rotary unit 10 and the second automatic rotary unit 30, and the first automatic rotary unit 10 and the second automatic rotary unit 30 are controlled by the controller 80. Consequently, it is possible to automatically control the rotational operations and rotational angles of the first jib 2 and the second jib 4 through the use of the first automatic rotary unit 10, the second automatic rotary unit 30, and the controller 80.

[65] Third, the first sensor 3 and the second sensor 5, which are connected to the controller 80, are mounted at the first jib 2 and the second jib 4 to prevent the first jib 2 and the second jib 4 from colliding with an obstacle at the time of rotating the first jib 2 and the second jib 4. Consequently, the first jib 2 and the second jib 4 do not collide with the obstacle even when the obstacle is located within rotational ranges of the first jib 2 and the second jib 4, and therefore, it is possible to prevent the damage to parts of the articulating type electric jib crane and the occurrence of a safety -related accident.

[66] Fourth, the bellows pipe 55 is mounted around the chain 53 by the first clamp 60 and the second clamp 70 to prevent dust generated during the winding and unwinding movement of the chain 53 of the hoist 50 from scattering to the circumference. Also, the respective parts of the articulating type electric jib crane are coated with an antistatic paint. Consequently, the articulating type electric jib crane according to the present invention maximally prevents the generation and scattering of dust, whereby the articulating type electric jib crane can be mounted and used in a clean room. Industrial Applicability

[67] As apparent from the above description, the articulating type electric jib crane according to the present invention is capable of repeatedly pulling up and conveying weights at sites where the convenience of the weights is repeatedly and frequently carried out, at sites having small spaces, or at sites where one or more obstacles exist. Consequently, the present invention has an industrial applicability.

[68] Although the preferred embodiment of the present invention has 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.

Claims

[1] An articulating type electric jib crane comprising: a jib post (1); a first jib (2) mounted at the upper part of the jib post (1); a first automatic rotary unit (10) including a first rotary shaft (11) mounted at the upper part of the jib post (1), a first rotary shaft support part (12) mounted at the first rotary shaft (11) and the jib post (1) to rotatably support the first rotary shaft (11), and a first worm speed reducer (18) mounted in the first rotary shaft support part (12) to rotate the first rotary shaft (11) and, thus, to rotate the first jib (2) coupled to the first rotary shaft (11); a second jib (4) mounted at a free end of the first jib (2); a second automatic rotary unit (30) including a second rotary shaft (31) mounted at one free end of the second jib (4), a second rotary shaft support part (32) mounted at the first rotary shaft (11) and the second rotary shaft (31) to rotatably support the second rotary shaft (31), and a second worm speed reducer (38) mounted in the second rotary shaft support part (32) to rotate the second rotary shaft (31) and, thus, to rotate the second jib (4) coupled to the second rotary shaft

(31); a hoist (50) mounted at the other free end of the second jib (4) to pull up a weight; and a controller (80) connected to the first worm speed reducer (18) of the first automatic rotary unit (10) and the second worm speed reducer (38) of the second automatic rotary unit (30) to control the first worm speed reducer (18) and the second worm speed reducer (38).

[2] The articulating type electric jib crane according to claim 1, wherein: the first rotary shaft support part (12) includes a first lower housing (13) mounted at the lower part of the first rotary shaft (11), a first lower bearing (14) mounted in the first lower housing (13) to support the rotation of the first rotary shaft (11), a first worm speed reducer box (15) mounted at the upper part of the first lower housing (13) such that the first worm speed reducer (18) is mounted in the first worm speed reducer box (15), a first upper housing (16) mounted at the upper part of the first worm speed reducer box (15) to support the upper part of the first rotary shaft (11), and a first upper bearing (17) mounted in the first upper housing (16) to support the rotation of the first rotary shaft (11); and the second rotary shaft support part (32) includes a second lower housing (33) mounted at the lower part of the second rotary shaft

(31), a second lower bearing (34) mounted in the second lower housing (33) to support the rotation of the second rotary shaft (31), a second worm speed reducer box (35) mounted at the upper part of the second lower housing (33) such that the second worm speed reducer (38) is mounted in the second worm speed reducer box (35), a second upper housing (36) mounted at the upper part of the second worm speed reducer box (35) to support the upper part of the second rotary shaft (31), and a second upper bearing (37) mounted in the second upper housing (36) to support the rotation of the second rotary shaft (31).

[3] The articulating type electric jib crane according to claim 1, wherein: the first worm speed reducer (18) includes a first worm wheel (19) coupled to the first rotary shaft (11) such that the first worm wheel (19) can be rotated with the first rotary shaft (11), a first worm (20) engaged with the first worm wheel (19) to transmit power to the first worm wheel (19), and a first drive motor (21) connected to the first worm (20) to transmit power to the first worm (20), the first drive motor (21) being also connected to the controller (80) such that the first drive motor (21) can be controlled by the controller (80); and the second worm speed reducer (38) includes a second worm wheel (39) coupled to the second rotary shaft (31) such that the second worm wheel (39) can be rotated with the second rotary shaft (31), a second worm (40) engaged with the second worm wheel (39) to transmit power to the second worm wheel (39), and a second drive motor (41) connected to the second worm (40) to transmit power to the second worm (40), the second drive motor (41) being also connected to the controller (80) such that the second drive motor (41) can be controlled by the controller (80).

[4] The articulating type electric jib crane according to claim 1, wherein: the first jib (2) is provided with a first sensor (3) connected to the controller (80), such that the first sensor (3) can be controlled by the controller (80), to restrict the rotational angle of the first jib (2) and to prevent the collision of the first jib (2) at the time of rotating the first jib (2); and the second jib (4) is provided with a second sensor (5) connected to the controller (80), such that the second sensor (5) can be controlled by the controller (80), to restrict the rotational angle of the second jib (4) and to prevent the collision of the second jib (4) at the time of rotating the second jib (4).

[5] The articulating type electric jib crane according to claim 1, further comprising: a bellows pipe (55) covering a chain (53) between the lower part of a main body (51) of the hoist (50) and a hook (52) of the hoist (50) to prevent dust generated during the winding and unwinding movement of the chain (53) from scattering to the circumference, the upper end of the bellows pipe (55) being coupled to the bottom of the main body (51) by a first clamp (60), the lower end of the bellows pipe (55) being coupled to the upper part of the hook (52) by a second clamp (70), wherein the first clamp (60) includes a fixing part (61) supported at the main body (51) of the hoist (50), a pair of first fastening pieces (62) configured to correspond to the upper end circumference of the bellows pipe (55), one end of each of the first fastening pieces (62) being fixed to a corresponding end of the fixing part (61), the other end of each of the first fastening pieces (62) being fixed to the main body (51), a pair of second fastening pieces (63) coupled to the corresponding first fastening pieces (62) to fix the upper end of the bellows pipe (55), and fastening bolts (64) to fasten the first fastening pieces (62) and the second fastening pieces (63) to each other.

[6] The articulating type electric jib crane according to claim 5, wherein the second clamp (70) includes a lower plate (71) located at the lower end of the bellows pipe (55), a pair of fastening pieces (72) coupled to the lower plate (71) to fix the lower end of the bellows pipe (55), and fastening bolts (73) to fasten the lower plate (71) and the fastening pieces (72) to each other.