Dredger having separately floating dredge and tail sections and method of dredging

Abstract

Underwater excavating apparatus including a floatable, anchorable tail section and a floatable, anchorable dredge section mounted on the tail section for longitudinal and swinging movement. The dredge section is swung relative to the tail section to dredge a swath and then advanced longitudinally relative to the tail section for cutting additional swaths. After being extended to its limit relative to the tail section, the dredge section is then anchored and the tail section unanchored and moved longitudinally up to its original position adjacent the dredge section after which the process is repeated.

Description

BACKGROUND OF THE INVENTION

This invention relates to underwater excavating apparatus of the type including a floatable dredging hull carrying a cutterhead which removes underwater material, such as earth. One such apparatus is disclosed in applicant's copending patent application Ser. No. 221,538, filed in the U.S. Patent Office on Jan. 28, 1972, now U.S. Pat. No. 3,777,375 and incorporated herein by reference. The apparatus disclosed in the copending patent application includes a pair of anchoring spuds, one which is generally anchored immediately below the dredge, and a pair of anchor cables which are anchored in firm earth on opposite sides of the bog being excavated. The spuds are alternately and oppositely moved to and from an anchoring position and a winch, mounted on the dredge hull, alternately winds and unwinds the anchor cables to swing the dredge in alternate directions about the anchored spud to "step" the dredge forwardly in a manner more particularly described in the referenced patent application. Depending on the distance stepped forwardly and the arc through which the dredge section is swung, the arcuate path of the cutterhead will sometimes partially overlap a portion of the previous path of the cutterhead thus decreasing the dredging efficiency. Also, the path of the cutterhead is such that a strip of undredged material is sometimes skipped, necessitating follow-up excavating to remove the uncut material. The time required to anchor one spud and release the other spud each time the dredge is stepped forwardly also decreases the operating efficiency.

After the prior art dredging apparatus is stepped forwardly a predetermined number of times, the anchoring cables are moved forwardly and reanchored. Movement of the cables is a very difficult task, and causes substantial operating "down time" for the dredge. Such breaks also interrupt the dredging momentum which a dredge operator builds.

The degree of swing of the prior art dredging apparatus is effectively limited to approximately a 90.degree. arc. If the dredge is swung beyond a 90.degree. arc, the anchoring cables tend to pull the anchored spud from the underwater earth. Accordingly, it is an object of the present invention to provide underwater excavating apparatus which will have a substantially increased dredging capacity and efficiency.

It is another object of the present invention to provide apparatus and method of the type described which will increase the arc through which the dredge cutterhead is swung.

It is another object of the present invention to provide an underwater excavating apparatus and a method which will eliminate the use of anchoring cables for swinging the dredge hull and will eliminate the requirement for anchoring a different spud each time the cutterhead is stepped forwardly.

A further object of the present invention is to provide dredging apparatus of the type described including a floatable dredging section which is longitudinally movable on an anchored tail section.

Still another object of the present invention is to provide dredging apparatus of the type described which swings a dredge section about the same pivot pin on successive forward steps of the dredge section.

Yet another object of the present invention is to provide dredging apparatus and method of the type described which initially forwardly moves the dredge section on an anchored tail section and then forwardly moves the tail section on an anchored dredge section.

A further object of the present invention is to provide apparatus of the type described which will minimize the loading on the anchoring spuds.

A still further object of the present invention is to provide apparatus of the type described including new and novel mechanism for relatively swinging the dredge and tail sections.

Other objects and advantages of the present invention will become apparent to those of ordinary skill in the art as the description thereof proceeds.

SUMMARY OF THE INVENTION

Apparatus and method for excavating material, such as earth, from an underwater basin including an anchorable tail section, and a dredge section which is mounted for incremental indexing forward movement on the tail section and is also horizontally swingable relative to the tail section.

The present invention may more readily be understood by reference to the accompanying drawings in which:

FIG. 1 is a top plan view of apparatus constructed according to the present invention;

FIG. 2 is a partly sectional, side elevational view of the apparatus illustrated in FIG. 1, parts being broken away;

FIG. 3 is an enlarged, sectional, top plan view, taken along the line 3--3 of FIG. 2;

FIG. 4 is an enlarged, sectional end view, taken along the line 4--4 of FIG. 3;

FIG. 5 is an enlarged, sectional, end view taken along the line 5--5 of FIG. 1;

FIG. 6 is a schematic top plan view illustrating the path of travel of a prior art dredge cutterhead;

FIG. 7 is a top plan schematic view illustrating the path of travel of a cutterhead constructed according to the present invention; and

FIG. 8 is a slightly enlarged, partly sectional, side elevational view of one of the anchoring spuds and the apparatus for lifting the spud.

Apparatus constructed according to the present invention comprises a forward, floatable dredging section, generally designated 10, and a rear, floatable tail section, generally designated 12. The floatable tail section 12 includes an elongate framework 14 spanning a pair of longitudinally spaced, hollow floatation devices 16 which are sufficiently buoyant to floatably support the tail section 12 on the water, generally designated W. The elongate framework 14 includes pairs of upper and lower longitudinal rails 15 which are spanned by vertical rails 15a and vertically inclined rails 15c, and connected by horizontal rails 15d. Mounted on the tail section 12 are a plurality of spud wells, generally designated 20, slidably receiving vertically movable spuds 22 which, when partially buried in the underwater earth E as illustrated in FIG. 2, anchor the tail section 12. Apparatus is provided for vertically retracting the spuds 22 and comprises a plurality of double acting, solenoid actuated, fluid pressure operated cylinders 24 (FIG. 8) actuating piston rods 26 which are connected to cables 28 trained around idler pulleys 29 mounted on the frame 14, and idler pulleys 30, mounted on the spud wells 20. The ends 28a of the cables 28 are fastened to the lower ends 22a of the spuds 22. When the piston rods 26 are retracted, the spuds 22 are removed from the earth E.

The floatable dredge section 10 is of the type described in U.S. Pat. Nos. 2,732,741 and 2,944,352, which are incorporated herein by reference. The hull 10 mounts a vertically movable dredge latter 23 which is vertically moved in a manner described in the referenced patent application. Rotatably mounted on the front of the dredge ladder 23 is rotatable, generally hollow, excavating cutterhead 25 for digging and collecting earth. A rotatable, cutterhead drive shaft 27 is connected with the rotary cutterhead 25 and is driven by a suitable hydraulic motor 29, mounted on the dredge ladder 23. A suction pipe 34, mounted on the dredge ladder 23, is connected at its rearward end to the inlet side of a dredge suction pump 32 supported on the hull 10. The pump 32 is driven by a suitable Diesel or electric motor 38. An outlet pipe or sleeve 36 is connected to the output side of the pump 32 and delivers the earth-water slurry sucked up by the pump 32 to a remote location.

Apparatus is also provided for anchoring the dredging hull section 10 and comprises a pair of vertical spuds 40 slidably received in spud wells 42 mounted on the stern of the hull 10. The dredge section anchoring spuds 40 are moved vertically by apparatus which is supported by the hull 10 and is constructed identically to the apparatus illustrated in FIG. 8 for raising the spuds 22 on the tail section 12. The spuds 40 are lowered to anchoring position when the tail section 12 spuds 22 are raised to permit tail section 12 to be moved toward the dredge section 10 as will be described more particularly hereinafter.

An intermediate hull section 11, includes an elongate framework generally designated 44. Guides 46 (Figures 2 and 5), mounted on the intermediate hull framework 44, are provided with recesses 47 lined with wear-resistant guide bushings 43 which slidably receive longitudinally extending rails or tracks 49 provided on laterally opposite, upper sides of the tail section 12 or framework 14. The tail section 12 mounts a pair of similar guides 46', which are inverted relative to the guides 46, including recesses 47' lined with nylon bushings 43' which slidably receive longitudinal guide rails 49' extending along and mounted to the laterally opposite, lower sides of the upper framework 44. The guides 46, 46' and rails 49, 49' permit the intermediate hull section 11 and the tail section 12 to be relatively longitudinally slid.

The stern of the dredge hull section 10 includes a pair of vertically spaced, rearwardly extending, hinge or connector plates 48 which are connected to a pair of vertically spaced, hinge or connector plates 50, provided on the front end of the intermediate framework 44, by a vertical hinge or pivot pin 52. The latter sides 48a and 50a of the hinge plates 48 and 50 converge toward the pivot pin 52 to provide wide, angular spaces between the hinge sections 48 and 50 to permit maximum swinging movement of the dredge section 10 and the tail section 12.

Apparatus, generally designated 51, is provided for swinging the dredge section 10 on the tail section 12 and includes a bar 54 freely swingably mounted on the hinge or pivot pin 52. The swinging apparatus 51 includes a plurality of double-acting, fluid pressure operated, solenoid actuated cylinders 56, 60, and 58, 62 pivotally connected to the dredge hull section 10 and the tail section 12 respectively, including piston rods 56a, 60a, and 58a, 62a, pivotally connected to opposite ends of the bar 54. When the tail section 12 is anchored and the piston rods 56a and 58a are extended, and the piston rods 60a and 62a are concurrently retracted, the hull 10 is swung counterclockwisely, in the direction of the arrow a (FIG. 3), to shift the hull 10 in an arcuate path about the axis of hinge pin 52 to the position illustrated in chain lines in FIG. 3. When the piston rods 56a and 58a are retracted and the piston rods 60a and 62a are extended, the hull 10 is swung oppositely, in the direction of the arrow b (FIGS. 1 and 3), to the position illustrated at 10b.

Apparatus is provided for indexing the intermediate framework 44 and the unanchored dredge section 10 forwardly and rearwardly on the anchored tail section 14 and comprises a motor 160, mounted on the intermediate frame 44, driving an endless chain 162 which is trained around a sprocket 64, fixed to a shaft 67 journaled on the frame 44. Fixed to the shaft 67 is a smaller diameter sprocket 66. A chain 68, having its ends 68a and 68b fixed to the rails 15 of the tail section 14, is trained around the sprocket 66 and a pair of idler sprockets 70 rotatably mounted on the upper framework 44. When the motor 160 is operated, the sprocket 64 will force the sprocket 66 to travel along the stationary chain 68 to move the framework 44 and dredge section 10 forwardly. A rack and a pinion drive gear could be substituted for the sprocket 66 and chain 68 if desired. The slurry discharge tube 36 includes an expansible section (not shown) to permit limited forward movement of the dredge section 10 relative to the tail section 14.

THE OPERATION

To condition the machine for operation, the spuds 22 on the tail section 14 are lowered to anchoring position, and the spuds 40 on the dredge section 10 are raised to the non-anchoring position, as illustrated in FIG. 2. Initially, the dredging hull section 10 will be presumed to be at a position illustrated at 10c in FIG. 7 and the cutterhead 25 is in the position illustrated at 25a. The dredge hull swinging cylinders 56 and 58 are operated to alternately extend and retract the piston rods 56a and 58a while the cylinders 60 and 62 are concurrently oppositely operated to retract and extend the piston rods 60a and 62a. When the piston rods 56a and 58a are firstly extended, and the piston rods 60a and 62a are firstly retracted, the hull 10 and cutterhead 25 will swing to the positions illustrated at 10b and 25b respectively in FIG. 7, to cut a swath 70. After this occurs, the motor 162 is operated to index the framework 44 and the floatable dredge hull 10 bodily forwardly to the positions illustrated in chain lines at 25e and 10e (FIG. 7). The pistons 60a and 62a are then extended and the pistons 56a and 58a are then retracted so that the cutterhead 25 cuts the next swath 72 as it moves to the position illustrated at 25f.

The motor 162 is again operated to index the framework 44 and the hull 10 forwardly so that the cutterhead 25 is positioned at 25g. The pistons 56, 58, 60 and 62 are continued to be operated to swing the cutterhead 25 and the motor 162 is intermittently operated until the intermediate framework 44 is fully forwardly positioned on the tail section 12, as illustrated in chain lines in FIG. 2. When this occurs, the spuds 40 on the dredge section 10 are then lowered to anchoring position, illustrated in chain lines in FIG. 2, and the spuds 22 on the tail section 12 are raised to the positions removed from the underwater earth E. The motor 160 is then reversely operated to draw the tail section 12 forwardly, relative to the now stationary dredge section 10. When the hull section is returned to the position illustrated in FIG. 2, the tail section spuds 22 are again lowered and the dredge section spuds 40 are raised so that the dredge hull section 10 can again be swung and advanced forwardly relative to the tail section 12.

The significance of applicant's invention can be better appreciated by comparing its operation with a typical prior art dredging operation, schematically illustrated in FIG. 6, wherein spuds 40, on the rear of a dredge hull 10 are alternately embedded in the earth E as the device is stepped forwardly after each cut. Assuming that the right spud 40a (FIG. 6) is initially in the ground, as the cutterhead 25' swings clockwisely as is illustrated by the arrow r (FIG. 6), it will cut a swath designated by vertical cross-hatch lines at 74. When the cutterhead 25 is swung to the right, to the position illustrated at 26a, the other spud 40b is then buried in the earth and the spud 40a is retracted. The dredge section then is swung in an opposite direction (opposite the direction represented by the arrow r) so that a swath, designated by horizontal cross-hatching 76, is taken. In the horizontally cross-hatched area, the path 76 of the cutterhead 25' overlaps at 70a the previous swath 74 which reduces the dredging efficiency. the area designated 80 represents a gap of earth between the swaths 74 and 76 which has been missed and which must be subsequently dredged. Not only is there substantial overlapping with the prior art dredge, but the "swing" of the cutterhead is substantially limited. If the arc is extended, the force on the anchored one of the spuds 40a and 40b tends to pull the anchored spuds out of the earth E.

As illustrated in FIG. 7, the cutterhead 25 in the dredge of the present invention can swing through an angle of 90.degree. from either side of a center plane p. Up to 45.degree. on either side of the plane p, there is substantially almost no overlap. A swing of 60.degree. on either side of the center plane p automatically widens the cut by one-third, and therefore reduces the number of pipe set-ups for the conduit 36.

It is to be understood that the drawings and descriptive matter are in all cases to be interpreted as merely illustrative of the principles of the invention, rather than as limiting the same in any way, since it is contemplated that various changes may be made in various elements to achieve like results without departing from the spirit of the invention or the scope of the appended claims.

Claims

I claim

1. Apparatus for excavating material, such as earth, from an underwater basin to enlarge the basin, comprising:

a floatable tail section;

a longitudinally aligned separately floated dredge section, displaceable longitudinally relative to the tail section, and including a dredging head for digging and collecting material to be dredged;

means for selectively anchoring said tail section in position;

means connecting the dredge section with said tail section for forward longitudinal movement relative to the tail section, and for generally horizontal swinging movement relative to the tail section in various relative longitudinal positions of the dredge section and tail section when the tail section is anchored in position and the dredge section is unanchored;

means for incrementally forwardly bodily longitudinally indexing said dredge section to various positions of extension relative to said tail section;

and means reactive between said tail and dredge sections for swinging said dredge section relative to said tail section in various relative longitudinally extended positions of said dredge section from said tail section, when the tail section is anchored and the dredge section is unanchored, to dredge material from said basin.

2. Apparatus as set forth in claim 1 wherein both said sections are selectively anchorable and said means for relatively bodily indexing said dredge section is operable to move said tail section toward said dredge section when said dredge section is anchored and said tail section is not anchored.

3. Apparatus as set forth in claim 1 wherein said means reactive between said tail and dredge sections includes a bar swingably mounted interjacent said tail and dredge sections, and sets of fluid pressure operated, extensible and retractable power cylinders connected between opposite ends of said bar and said sections.

4. The apparatus of claim 1 wherein the means connecting the dredge section with the tail section comprises relatively telescoping members and said means reactive for swinging the dredge section relative to the tail section is connected to one of said members.

5. The apparatus as set forth in claim 1 in which said tail section includes a telescoping framework attached to said dredge section and further comprises a plurality of separate floats for supporting the framework.

6. The apparatus as set forth in claim 1 in which means is also provided for selectively anchoring said dredge section in position and said tail and dredge sections have vertical guides; said anchoring means for both sections comprising raisable and lowerable spuds movable in said guides from a lowered position anchored in the basin bottom to a raised unanchored position, and mechanism for selectively raising and lowering said spuds.

7. The apparatus as set forth in claim 1 in which said tail section supports an elongate slide frame; an extensible slide boom is supported by said slide frame and is extendible longitudinally forwardly therefrom; said means mounting the dredge section for swinging movement relative to the tail section, comprising a vertical pivot part carried by said boom and to which said dredge support section is connected for horizontal swinging movement.

8. The apparatus of claim 7 in which said reactive means comprise extensible and retractible, fluid pressure operated power cylinders connected between said pivot part and dredge section and between said pivot part and tail section.

9. A method of excavating material, such as earth, from an underwater basin with a dredge having an anchored floating dredge cutterhead support section pivotally connected with an unanchored separately floated tail section comprising the steps of:

anchoring the floatable tail section and unanchoring the dredge cutterhead support section;

reacting the unanchored dredge cutterhead support section with the anchored tail section by using the tail section as a fixed support to horizontally swing the dredge cutterhead support section in an arcuate path of travel relative to the anchored tail section, and dredging material while traveling in said path; and

repetitively bodily extending the dredge cutterhead support section further forwardly of the anchored tail section and repetitively swinging the dredge cutterhead support section in an arcuate path following said repetitive extensions to dredge material.

10. The method of claim 9 including the further steps of:

anchoring said dredge cutterhead support section and unanchoring said tail section;

bodily moving said tail section toward said dredge cutterhead support section by using the dredge cutterhead support section as a fixed support and reacting against it; and

the reanchoring said tail section and unanchoring said dredge cutterhead support section so that the dredge cutterhead support section can again be extended from the tail section and swung in a dredging arc of travel.