KR100751593B1 - Apparatus for Releasing Rack Chock of Jack-up Rig - Google Patents

Abstract

The "fixed" rack choke of the jack-up excavator is released by the moving force applied to the rack choke by the worm gear assembly. The worm gear assembly includes a gear wheel having a plurality of teeth and a worm gear member having a worm screw coupled with the teeth for transmitting rotational force from the drive motor to the gear wheel. The shaft of the cogwheel is linked to the rack choke, so that the rack choke is separated from the contact surface of the leg cord when the cogwheel rotates.

Jack Up Excavator, Rack Choke, Leg Cord, Gear Wheel, Worm Gear, Mineral Exploration, Offshore Excavator, Hull

Description

Apparatus for Releasing Rack Chock of Jack-up Rig}

1 is a perspective view of a jack up excavator of the present invention,

2 is a detailed view showing the rack choke in combination with the Dara cord;

3 is a detailed view showing a two-part worm gear release mechanism of the present invention connected to a hydraulic motor;

4 is a detailed view of a release mechanism rotatably coupled with a worm gear release mechanism;

5 is an exploded view showing another embodiment of the worm gear holder.

[Explanation of symbols on the main parts of the drawings]

10: jack up excavator 12: hull

14: leg 18: leg code

19: rack choke assembly 20; Cord rack

22, 28: tooth 24: chalk

26, 30: jack screw assembly 32: toothed wheel

33: housing 34: worm gear member

38: center shaft 80: worm gear

TECHNICAL FIELD The present invention relates to offshore excavators suitable for conducting mineral exploration and production operations, and more particularly to self-elevating jack-up excavators incorporating rack chock.

Jack-up excavators have been widely used in the form of offshore work platforms that are particularly suitable for development in medium depth areas. Typically, this type of excavator uses jack lifting legs to support the work platform or hull in an elevated position at a selected location. After towing the jackup excavator to the required location, the legs are extended upwards through the wells in the hull so as not to interfere with the towing. Once the excavator is moved to the selected position, the legs are lowered to the sea floor and the power jacks are used to raise the hull to a working height higher than the wave height.

The hull and legs are firmly coupled to each other through rack tooth systems formed on the support legs, and oppose each other to mate the rack portions of the rack chokes. The rack chokes move in the horizontal and vertical directions to form a mating alignment with the leg cords. Once the alignment is completed, the rack choke will firmly connect the hull to the legs of the excavator. During operation of the excavator, the legs and the hull keep their unique coupling locked, thus resisting the overturning force exerted on the legs by the waves.

When firmly joining the legs and the hull, considerable pressure acts on the surface of the joining teeth of the leg cord and rack choke. In practice, the teeth are locked and as a result it is very difficult to disengage the rack chocks from the leg cords.

Under certain circumstances, the bond between the bridge and the hull must be broken to relocate the hull or the entire excavator. Often, conventional methods and equipment do not generate sufficient force to release the "fixed" jack.

Until now, various methods have been used to release the screwjack. One such conventional method is the combustion of a jack bearing plate or cap to break the rigid bond between the leg cord and the rack choke. However, this method is labor intensive, time consuming and relatively expensive. In addition, in order to regain a firm coupling of the hull to the legs, the cap must be replaced prior to moving the screw jack laterally to engage the leg teeth.

Other known techniques include the use of a wedge-shaped device, in which the inclined surface of the wedge is intended to release the choke mechanism. Such a configuration is described in US Pat. Nos. 5,486,069 and 5,611,645, issued to John O. Breeden. Both patents disclose fastening systems using toothed coat chokes that are adapted to move in the horizontal and vertical directions. This toothed rack choke has upper and lower slopes. The fixing system includes upper and lower wedges contacting the upper and lower inclined surfaces. The upper and lower wedges are moved to engage the upper and lower inclined surfaces of the rack choke to release the coupling between the leg cord and the rack choke. Although this structure is often satisfactory, there is still a need for a simpler design with regard to the release of rack chokes.

The present invention seeks to provide an improved mechanism capable of releasing the drawbacks associated with conventional constructions while at the same time releasing the rack chocks from the secure engagement with the leg cords.

It is therefore an object of the present invention to provide a jack up excavator having a rack choke release mechanism.

Another object of the present invention is to provide a rack choke release mechanism capable of preventing the locking of the rack choke to the leg cord.

It is a further object of the present invention to provide an improved jack up excavator assembly which eliminates the risk of fixed rack chokes.

These and other objects of the present invention are achieved through the provision of a worm gear assembly interlocked to a frame supporting a rack choke of a jack up excavator. The worm gear assembly includes a gear wheel having a plurality of inner recessed teeth positioned at circumference over at least a portion thereof, and a worm gear member. The teeth have an upper surface concave inward. The gearwheel has a hollow body mounted to a shaft that is linked to the rack choke.

A worm screw is formed on the circumference of the middle portion of the worm gear member. The worm screw generally has a truncated cone shape. The worm gear member has a center shaft connected to the drive motor, and when the screw is engaged with the teeth of the gear wheel, the rotational force from the drive motor is transmitted to the shaft of the gear wheel.                         

As the cogwheel rotates, movement force is applied to the rack choke, which results in a position shift for engagement with the contact surface of the leg cord of the rack, and also the contact surface of the leg cord when the cogwheel rotates in the opposite direction. Separation from is achieved.

In the figure, reference numeral 10 denotes a jack-up excavator in which the state in the raised position is schematically shown. The hull 12 is supported on the water surface 16 by a number of legs 14. The legs 14 land on the sea floor (not shown), supporting the hull and at the same time supporting the work carried out on the deck of the hull.

Each leg 14 has a number of leg chords 18, each leg cord 18 being provided with a cord rack 20 having a series of horizontally extending teeth 22. Lifting and lowering of each leg is performed by the action of a jack system located above the rack choke assembly 19 (FIG. 1). Conventional leg jacking systems use a drive pinion that is coupled to the jacks. Jacking systems use jack pinions that engage the opposite teeth of each leg cord rack 20.

After moving the excavator 10 to the selected position, while lowering the legs to the sea floor, the hull is raised. In order to keep the hull at an elevated position above the wave height, the rack choke assemblies 19 must be moved to engage the leg cord rack 20.

As shown in FIG. 2, the apparatus of the present invention includes a rack choke assembly that engages or disengages the teeth 22 of the leg cord rack 20 with the teeth of the rack choke assembly. Each rack choke assembly 19 has a number of horizontally extending teeth 28 that engage with the teeth 22 of the leg cord rack 20. The teeth 22, 28 have a mating profile to make contact between the teeth coupled better.

The rack choke assemblies 19 are supported by the hull 12 and move to engage or disengage from the cord racks 20 through a system of horizontal drive pinions or jack screw assemblies 26. Typically, four horizontal jack screw assemblies 26 are provided for each leg cord rack 20.

Multiple, typically four vertical jack screw assemblies 30 are provided per leg choke for the vertical adjustment of the rack choke position relative to the leg cord rack 20. Both the horizontal jack screw assembly 26 and the vertical jack screw assemblies are housed in a housing 33, which moves along the jack screw assemblies 26 and 30, thereby rack choke assembly 19. ) Is moved to engage or separate from the contact surface of the teeth 22 of the leg choke rack 20.

As shown in FIGS. 3 and 4, each jack screw assembly 26, 30 has a worm gear portion 80, ie a worm gear assembly, which has a gear wheel 32 and a gear wheel 32. It has a worm gear member 34. The worm gear portion 80 is mounted to a housing 33 that protects the rotary coupling portions of the jack screw assemblies 26 and 30.

Each worm gear portion 80 ensures active movement of the rack choke assembly 19 through rotation of the worm gear member 34 and the toothed wheel 32. When the cogwheel 32 and the worm gear member 34 are coupled to each other, the rotation from the power source is transmitted to the worm gear member 34 and the cogwheel 32 and then converted into a linear movement of the choke 24 as described below. . The longitudinal axes of the central shaft 36 of the worm gear member 34 and the central shaft 38 of the wheel 32 are perpendicular to each other.

The gearwheel 32 includes a hollow body 40 having a first cylindrical portion 42, a second cylindrical portion 44, and an intermediate cylindrical portion 46. A plurality of parallel teeth 48 are formed on the outer circumferential surface of the intermediate cylindrical portion 46 to extend to the line 50 on the first cylindrical portion 42, and also the first cylindrical portion 42 and the intermediate cylindrical portion ( It extends to the line 51 separating the 46.

Each tooth 48 has an inner concave contact surface 52 engaged with the corresponding surface of the worm gear, as will be described later. A rotating central shaft 38 is inserted into the central opening 54 formed in the gearwheel 32. The intermediate cylindrical portion 46 is connected to the second cylindrical portion 44, which is a portion whose diameter is enlarged by the flange 45. A symmetrical flange 57 is fixedly attached to the outer circumferential edge 59 of the second cylindrical portion 44 (see FIG. 3). Attachment of the flanges 55, 57 may be made by bolts 43 or in other suitable manners known to those skilled in the art.

As can be seen with reference to FIGS. 3 and 4, the worm gear member 34 includes a pair of cylindrical portions 56, 58, a pair of bevel portions 60, 62, and a diameter reducing attachment portion. And an elongated body having a 64 and a central portion 66. The central portion 66 has a diameter reducing middle portion and a diameter expanding outer portion.

The center shaft 36 is attached to the motor adapter 70, and the motor adapter 70 is fixed to the gear reducer 72. The gear reducer 72 is adapted to interlock with a drive means 74 or other suitable drive means, which can be a hydraulic motor. The motor 74 applies a rotational movement force to the worm gear member 34 to transmit torque to the gearwheel 32.

As can be seen more clearly with reference to FIG. 3, each worm gear portion 80 has a spline positioned between a flange 84 of the motor adapter 70 and a collar 86 surrounding the opening formed in the worm gear holder. 82 are provided. These splines 82 are provided in two or more and are designed to provide auxiliary structural strength to the worm gear portion 80 with rotating shafts extending in series from the motor 74 to the worm gear member 34. The shafts extend coaxially with each other and are interlocked with each other to transmit rotational force.

The worm gear portion 80 also includes a worm gear holder 90 (FIG. 3) formed as a box-shaped hollow body consisting of an outer wall 92, an inner wall 94, a front plate 96, and a rear wall 98. The inner wall 94 is fixedly attached to the inner wall 100 of the housing 33 by welding or the like. In this way, the worm gear holder 90 is supported by the walls of the housing 33 at a distance from the choke 24.

The front wall 96 is provided with openings 102, 104, which are surrounded by a collar 86, and the opening 104 is surrounded by a collar 106. The openings 102, 104 are adapted to alternately receive the worm gear member 34 during engagement or detachment of the choke 24 to the leg cord 18. The opening 102 acts as an insertion position for the right screw of the worm gear member 34, and the opening 104 acts as an insertion position for the left screw of the worm gear member 34, ie the worm gear member 34. Make the worm screw rotatable in the opposite direction.

The holders 90 are precast to have right and left screws. When installing to the worm gear part 80, the operator selects which of the opening 102 and the opening 104 to receive the worm gear member, and installs the worm gear member 34 in the selected opening. When the rotational direction of the worm gear member 34 is changed, the rotational direction of the motor 74 is also changed so that the choke 24 can be separated from the leg choke teeth 22.

Figure 5 shows another structure for the worm gear holder. As can be seen with reference to the drawings, the worm gear holder 110 includes an attachment plate 112 for fixing to the wall 100 of the housing 33. The worm gear holder 110 is also provided with a worm gear member 34, ie one sleeve 114 for receiving a worm screw. The plate 112 also supports the toothed wheel cover 116. The longitudinal axes of the cover 116 and the sleeve 114 intersect at right angles to each other, and the worm gear member 34 and the wheel are formed by a cutout (not shown) formed in the contact surface of the sleeve 114 and the cover 116. Coupling between the teeth of (32) is made.

As can be seen with reference to the drawings, the worm gear member 34 is accommodated in the central opening 118 of the sleeve 114. Bearing housings 120 and 122 are coupled to the open ends of the sleeve 114. The bearing housings 120 and 122 are coupled to both sides of the shaft 36 of the worm gear member 34 to facilitate rotation of the worm gear member in response to the torque transmitted from the motor 74.

Coupling 120 is coupled between the bearing housing 122 and the motor adapter. Similar to the embodiment shown in FIG. 3, the motor adapter 70 is coupled to a gear reducer 124, which is linked to a motor 74.

The central opening 130 of the cover 116 is surrounded by the flange 132. A tooth 136 is formed on the outer surface of the jack screw nut 134 having a screw formed therein. The tooth 136 is coupled to the screw of the worm screw to apply a rotational force to the screw portion 134 when the worm gear member 34 rotates. A jack screw 138 is coupled to the screw 140 formed on the inner wall of the jack screw nut 134 so as to rotate clockwise or counterclockwise according to the rotation direction of the worm gear member 34.

A cover plate 142 is mounted to the exterior of the cover 116, which is provided with a plurality of holes 144 that align with the holes 146 on the flange 132. The holes 144 are one example of coupling the cover plate 142 and the cover 116 to accommodate a suitable fixing means such as bolts. Although not shown, the assembly 110 is positioned in a manner similar to the worm gear portion 80 in the housing 33 to provide a connection to the jack screw 138 while simultaneously transmitting a linear movement force.

An optional collapsible bearing assembly 150 may be installed between the jackscrew 138 and the choke 24. This collapsible bearing assembly 150 is provided with a bearing plate 152 in contact with the end 148 of the jack screw 138. Also provided is a contact plate 154 in contact with the rack choke 24. A collapsible insertion member 156 is installed between the contact plate 154 and the bearing plate 152. A collapsible removal medium 158 is positioned between the parallel plates forming the collapsible insertion member 156, so that the rack choke can be separated from the leg cord if necessary. The contact plate 154 and the insertion member 156 are fixed to the bearing plate 152 at the same time as being fixed to each other by bolts 158, the bearing plate 152 is a jack screw ( 138). Of course, it is also possible to use other fastening means if necessary.

Referring again to FIG. 4, the central portion 66 of the worm gear member 34 is machined to form a worm screw 76, wherein the worm screw 76 is coupled to the teeth 52 to drive the drive means 74. The transmission to the gearwheel 32 of the power generated by this is aimed at. As shown in FIG. 4, the screws 76 have a conical shape with a flat outer surface that engages the teeth of the wheel 32.

The screws 76 have a working depth and pitch diameter that are generally similar to the depth and pitch of the teeth 48. The cord thickness of the tooth 48 substantially matches the thickness of the worm screw 76. The circular pitch of the screw 76 is generally the same as the teeth 48, ie corresponding points on the circumference of the worm gear screw. The spacing of the teeth 48 is approximately equal to the distance between the upper end of the screw 76 and the bottom circumferential surface of the central portion 66. As a result, when the screw 76 is engaged with the tooth 48, the screw 76 and the tooth 48 are engaged with each other.

When a rotational force is applied to the shaft 36, torque is transmitted to the gearwheel 32. Since the center shaft 38 of the toothed wheel 32 is interlocked with the rack choke assembly 24, the latter rack choke assembly 24 is moved to engage or separate from the leg cord teeth 22. The rack choke assembly 24 is coupled or disengaged according to the rotational direction of the shaft 36.

2 to 4, each rack choke assembly 24 has two horizontal worm gear sections to allow the rack choke 24 to be precisely positioned on the horizontal and vertical planes with respect to the leg cord teeth 22. In the embodiment shown in FIGS. 80 and two vertical worm gear portions 80 are provided. The design and structure of each worm gear portion 80 is similar to the design and structure described above. All the moving parts and the rotating parts of the release mechanism are accommodated in the housing 33, thus preventing the worker from being injured.

Worm gear assembly 30 can be used to release a locked rack choke. The use of worm gear parts of different diameters simplifies the separation of leg cords and rack chocks. In addition, less power is required to move the rack choke assembly in engagement with the leg cord.

While the embodiments of the present invention have been described so far, the present invention is not limited thereto, and various changes and modifications may be made within the scope of the invention described in the claims.

Worm gear assemblies can be used to release locked rack chokes. The use of worm gear parts of different diameters simplifies the separation of leg cords and rack chocks. In addition, less power is required to move the rack choke assembly in engagement with the leg cord. As the cogwheel rotates, movement force is exerted on the rack choke, resulting in a position shift for engagement with the contact surface of the leg cord of the rack, and also when the cogwheel rotates in the opposite direction, Separation from the contact surface is achieved.

Claims (24)

An apparatus for releasing a rack choke pressure-coupled to a contact surface, the apparatus comprising: A worm gear assembly interlocked with the rack choke, And means for applying a rotational force to the worm gear assembly, wherein the worm gear assembly moves the rack choke to release the engagement with the contact surface by converting the rotational force into a linear movement of the rack choke. Rack choke release. The method of claim 1, And the worm gear assembly includes a gear wheel and a worm gear member coupled to the teeth of the gear wheel to transmit the rotation force from the rotational force applying means to the gear wheel. The method of claim 2, And said tooth wheel comprises a generally cylindrical hollow body fixed to a wheel shaft coupled to said rack choke. The method of claim 3, wherein And said worm gear member comprises a central drive shaft extending generally at right angles to said wheel shaft. The method of claim 2, The toothed wheel has a plurality of teeth located along its circumference, the worm gear member has a worm screw coupled with the tooth, the worm gear member is coupled to the rotational force applying means characterized in that the rack choke release Device. The method of claim 2, The torque applying means is a rack choke releasing device, characterized in that it comprises a hydraulic motor connected to the gear reducer connected to the motor adapter fixed coaxially with the worm gear member. The method of claim 2, The worm gear member is a rack choke release device, characterized in that the worm screw is formed and comprises an intermediate portion having a diameter reducing center portion between the large diameter end portions. The method of claim 5, Wherein each of said teeth has a middle portion concave inwardly. 6. The rack choke release device according to claim 5 wherein the worm screws have a generally truncated cone shape. The method of claim 8, And said teeth are oriented in a generally parallel relationship with respect to the central axis of said gearwheel. The method of claim 1, The worm gear assembly includes at least one horizontal worm gear unit for moving the rack choke along a horizontal plane, at least one vertical worm gear unit for moving the rack choke along a vertical plane, and the horizontal worm gear unit and the vertical worm gear unit, respectively. Rack choke release device comprising a power means for transmitting the force. The method of claim 11, The power means is a rack choke release device, characterized in that it comprises a motor interlocked with each worm gear. The method of claim 11, Each of the worm gear parts has a tooth wheel mounted on a center shaft that engages the rack choke, and a worm screw that engages the teeth of the tooth wheel and causes the tooth wheel to engage the jack screw of the rack choke. Rack choke release device characterized in that it comprises a worm gear member having a screw formed inside the gear wheel. The method of claim 13, Each of the worm gear parts includes a worm gear member holder for accommodating the worm gear member, and the worm gear member holder includes an outer frame having an opening to allow the central shaft of the worm gear member to extend outwardly. Choke Release. The method of claim 14, The power means further comprises a gear reducer mounted coaxially with the motor, and a rack choke releasing device further comprising a motor mounted to be interlocked between the gear reducer and the worm gear member. An apparatus for releasing a rack choke pressure-coupled to a contact surface of a leg cord of a jack-up excavator, A worm gear assembly interlocked with the rack choke, Means for applying a rotational force to the worm gear assembly, wherein the worm gear assembly moves the rack choke by converting the rotational force into a linear movement of the rack choke to release the engagement with the contact surface, and the worm gear assembly It includes one or more toothed wheels with a plurality of teeth formed along the outer surface, and one or more worm gear member is formed with worm screws, the teeth are coupled to the worm screws to apply a moving force to the rack choke Thereby separating the rack choke from the contact surface of the leg cord when the worm gear assembly is rotated. The method of claim 16, The gear wheel includes a hollow body mounted to the jack screw of the rack choke, the worm gear member includes a center drive shaft interlocked with a drive motor, and the jack screw is mounted at a right angle to the center drive shaft. Rack choke release device, characterized in that the jack-up excavator. The method of claim 16, And said tooth wheel has a plurality of inner concave teeth positioned along its perimeter over at least a portion thereof and said worm gear member has said diameter reducing center portion. The method of claim 16, The worm gear assembly includes one or more horizontal worm gear parts for moving the rack choke along a horizontal plane, and one or more vertical worm gear parts for moving the rack choke along a vertical plane, wherein each of the worm gear assemblies includes the horizontal worm gear part. Rack choke releasing device of the jack-up excavator, characterized in that it comprises a power means for transmitting the respective moving force to the vertical worm gear. The method of claim 19, The power means is a rack choke release device of a jack-up excavator, characterized in that it comprises a motor interlocked with each worm gear. The method of claim 19, Each of the worm gear parts includes a worm gear member holder for receiving the worm gear member such that the screws of the worm gear member are oriented in a predetermined direction with respect to the teeth of the tooth wheel, wherein the teeth rotate the tooth wheel of the rack choke. A rack choke release device for a jack up excavator, wherein the internal screw is formed to engage with the jack screw. The method of claim 21, The worm gear member holder includes an outer body having an end plate formed with an opening to allow the central shaft of the worm gear member to extend outwardly, The power means is a rack choke release device of a jack up excavator, characterized in that located on the outside of the outer body. The method of claim 16, And the worm gear assembly includes a pair of horizontal worm gear units and a pair of vertical worm gear units to precisely position the rack choke with respect to the leg cords of the jack-up excavator. The method of claim 16, The rack choke release device of a jack up excavator further comprising a collapsible bearing plate assembly positioned between the jack screw and the rack choke body.

Images