NL7811837A - STABILIZATION SYSTEM OF A CRANE TOOLS. - Google Patents

Description

785172 / L / PB \ »

Applicant: VARITRAC A.G., in Zug, Switzerland

Title: Stabilization system of a working vessel with cranes.

The invention relates to a stabilization system for a work vessel with ship hulls located in the working condition below the water surface on which hollow columns are placed, which carry a working platform situated above the water level with one or more heavy cranes, wherein the stabilization system above and below the ambient water Mirror-located water-ballast reservoirs comprise, on the one hand, the outpouring of water from the above-water reservoirs, and, on the other hand, the inlet of water into the underwater ballast reservoirs is selectively controlled depending on the moment of moment of the crane load moment during the load maneuver.

Such a system is known from German patent application (Offenlegungsschrift) Nr. P 28 02 2 ^ 9 · 3 ·

The object of the invention is to provide a special embodiment using this known technique, which leads to a further simplification of the device for vessel stabilization during load displacement through one or more cranes placed on the vessel, wherein also the deviations from the occurring horizontal position to an absolute minimum (eg 1 °) and nevertheless the load maneuvers can be carried out at the greatest speeds that allow the arrangement and control of the crane concerned as such, so without having to introduce delays to stabilize -tie requirements.

In this connection, the invention further aims to arrange the said lower ballast chambers in such a way that a suitable railing of the adaptation to the adjustment forces to be obtained for the stabilization can be obtained therewith than by means of air supply. In those rooms and storage tanks to be set up for this purpose with compressed air.

Furthermore, by use of advantageous embodiments, 30 µm. intended to maintain the principle under the given conditions, let the ballast water displacement affect the vessel's overall load to a relatively small extent and, by placing the 7811837 2 _ 2 _ water ballast chambers number and size for the most normal in the vessel, Conditions which may occur in practice can be kept limited. The invention and details which may advantageously be applied in practice are hereafter elucidated on the basis of a few calculations and exemplary embodiments which are explained in schematic figures of the drawing.

In the drawing: Fig. 1 is a perspective diagram of a floating body on which a vertical load and a moment are applied; 1 ° fig. 2 the same body in horizontal position with indication of the corapenation forces required to assume that position; fig. 3 shows a cross-section through a vessel according to the invention along the line III-III of fig. * », two cranes being shown in elevation; Fig. K is a further schematic top view of Fig. 3 on a smaller scale, pivoted by 90 ° to the right about an axis perpendicular to the drawing plane compared to Fig. 3; Fig. 5 shows a simplified crane representation with instructions for calculation purposes; FIG. 6 is a schematic plan view of the working platform of a vessel according to the invention, belonging to FIGS. K and 5 and rotated 90 ° clockwise relative to those figures about an axis perpendicular to the plane of the drawing, and FIG. 7 is a diagram concerning the filling of water ballast chambers 25 in different steps of an exemplary load maneuver. Floating Body Compensation Principle:

When a vertical load G is applied to a floating body, as indicated by dotted lines by 1 in Fig. 1, generally the following changes occur in the position of this Body, measured with respect to a fixed coordinate system X - Y - Zs - vertical displacement (z) - angular displacement if x with respect to the X axis (pendulum axis) - angular displacement ^ y with respect to the Y 'axis (stamping axis).

To counteract all these changes, at least three 35 summing forces must be applied, gripping three different points .__ 781 1 8 37 o _ 3 _

If compensation of two of the three degrees of freedom is sufficient, only two compensation forces are required.

With one compensation power, only one degree of freedom can be influenced.

5 If the compensation forces only work in one direction, further possibilities arise.

Thus it is e.g. possible to compensate both angular rotations with three or more downward acting compensation forces.

Compensation system with two compensation forces: 10 It has been found that for the most common, normal circumstances when using a stabilization system as mentioned above for so-called semi-submersible crane ships, two compensation forces can suffice, with which the two angular rotations zero.

The vertical displacement is not compensated. The location of the compensation forces A and B is fixed in the construction, if, as described below, it takes place with the aid of water-ballast chambers, which are placed in pairs one above the other and whereby the vertical axes of those chambers through points 2 and 3 run (coordinates a, b for point 3 and a, -b for point 2).

20 If now the magnitude G and the point of application (x, y) of the verticals load force are given, the magnitude of the two compensation forces A and B can be calculated, which is necessary to remain horizontal of the vessel:

For this purpose, the resulting mxen Mx with respect to the X axis = 0 and 25 Hy with respect to the Y axis = 0.

To this end: (A-B) b = Gy (A + B) a = Gx so: 30 A = i G (- + B = i G (I - J)

The change in draft can be calculated from the total load variation and the waterline intersecting area (Atf)

"S-A-B

35 z = —————

Aw 78 1 1 8 37 * _ k _

It can be seen from this that for x = a the draft does not change. Before a crane is put into operation on the ship, the gross and position and the associated values of the compensation forces are calculated, which are referred to as the zero values A0 and B0. These 5 are stored in the memory of a computer.

If now the magnitude and / or the location of the load G changes, the calculated values of the compensation forces also change.

These changes A A = A-A0 resp. A B = B-BQ are passed on to the control system "which sets the compensation forces.

Implementation of compensation system (fig. 3).

As mentioned in the introduction, the invention finds application bi; a vessel (see fig. 3-5) with two parallel underwater turnips * f, 5i on which hollow columns 6-11 are placed, which has a working platform 13 located above the water level 12 with one or more heavy cranes 1 * f, 15 (e.g. carry a 2000 and a 3000-tonne crane).

The stabilizing system now comprises under each of the cranes two superimposed water-ballast reservoirs, the pair of which located in column 6 under the crane 1A is indicated by A, namely A-j for the upper reservoir and Ag for the lower reservoir.

The pair of reservoirs in column 7 is correspondingly indicated by B1.2. Compensation forces A, B (fig. 2) are applied in a known manner, by allowing water to flow out or to flow in freely. in the reservoirs Ai} 2 and B1,2. An upwardly directed force is applied by discharging water from a reservoir A1 or B-] located above the water mirror.

A downwardly directed force is generated by flowing water into a reservoir A2 or B2 located below the water surface.

Because existing level differences can be used during the crane load maneuvers, very large volumes of water can be moved in a short time, without the need for pump installation3, which is essential for creating the possibility to momentarily change the vessel. horizontal when lifting, slewing and dropping outboard loads by the cranes.

It can be seen that for this purpose the water-ballast reservoirs A-j, B-] are located above the water table 12 and the outflow is controlled by control valves 16 and 17, which are selectively controlled, as will be explained below. The outflow is effected through downcomers 18, 19 (of which only one is shown for each of the reservoirs Ai, Bi) which are passed through the underwater reservoirs kp, B2 and through the bottom of the hulls 4, 5. Such water inlet control valves 21, 22 are arranged in the bottoms of the reservoirs kp, B2 for the inlet pipes 23, 24, only one of which is also shown for each reservoir. Although it is possible to expel water, bp, B2 from these chambers by supplying compressed air therein with opened valves 21, 21, respectively. 22, it appears that the load maneuvers can be performed without the need for a suitable compressed air installation, as will be explained below for a particular maneuvering cycle as an example. The reservoirs kp, B ^ can be emptied after such a cycle, by pumping the water from a lower chamber to an upper chamber 15, as indicated by the dotted lines 23, 26 (dotted lines, of course, these are placed within columns 6, 7 ). The top of the reservoirs A2, B2 can be in open communication with the outside air, as indicated by the pipe pieces 27, 28. A pump line 20 (not shown) can of course also be connected to the upper reservoirs, for which purpose water can be replenished from the surrounding water if necessary.

The valves and connecting pipes must, of course, be sufficiently large and sufficient in number, in order to be able to realize the desired volumetric flow with completely exhausted exhaust for A1B-]. inlet 25 ^ 2 'B2 *

In a suitable embodiment, for example, a displacement fan becomes approx. 4000 m3 of water made possible in 40 seconds.

The system must be "charged" before use by pumping out the lower reservoirs A2, B2 and pumping out the upper reservoirs Ai, Bi.

It is therefore advantageous to place the reservoirs two by two above each other.

This does not disturb the balance by pumping water from the lower to the upper reservoir.

This transfer can therefore already take place during the compensation procedure 7811837 6, if the lower reservoir is no longer completely empty and the upper reservoir is not completely full.

The control system.

The change in compensation forces calculated for a given change in loading is translated into a desired water level in each reservoir, or into a desired volume of water displacement (setpoint).

With level control, the water level is continuously measured. If the measured value deviates from the desired value, a valve is opened.

A multiple valves with mutually differing capacities can be used per reservoir. Selection and number of activated valves is then determined as a function of the difference between the value desired for horizontal location and the measured value of the water level.

'15 A second possibility is volume control. In this case the position of the valves is measured. With the aid of the associated valve characteristics, which are entered as fixed data into the computer, the volume flow is integrated over time until the desired volume is reached.

20 The desired values for the water levels (or volumes) for maintaining horizontal position at any time are calculated directly from the instructions of the various measuring sensors on the cranes (swivel angle, top angle, load).

With the help of all kinds of known data (such as boom length, crane pivot distance to boom pivot, crane center of gravity position and counterweight, etc.), the required change of the summing forces is calculated.

In this calculation, the influence of various load forces can be taken into account.

50 With regard to the measurement data indicated in Figs. 3 and 5 above, the formulas below have been determined for the calculation of the side compensation forces A ^ and Bj ^, when working with two cranes 14 and 15, taking into account: weight of the load in main lifting block G ^, Gg 35 - weight of the cranes, divided by weight of crane body Gg i__ 78 1 1 8 3 7 fl 7 crane head G ^ and counterweight G ^.

In the formulas, the letters A or B have been added to the indexes to indicate the crane to which the data refer, i.e. A for crane 1 * f and B for crane 15 in fig. 3 · 5 See also the instructions in fig. B for the distances to X and Y axis.

The formulas can of course be extended to compensate for the loads in auxiliary lifting blocks GA 2 3 'GB 1 2 and to use more cranes.

10 Example calculation of compensation forces: + i (Ga + Gta) (PA + lAcos ƒ A) + gha RhA + GcARCA · (Si ° ^ A _ C0SK.

b “a - i (Gj + Gtb) (P Β + 1β cos ^ fl) + GhbShb + GcbRcb.

sin D _ cos $ -o 15 <—Γ1 + 5 - i (Ga + GtA5 (PA + 1AC0S Ϋ A ^ + ÖHA ¾A + GCAECA * sin $. cos 2 ^.

(- “b— + a} + £ (Gg + Gjjig) (Pg + lgCOs ΫB) + Ghb% B + GCBRCB.

sin ^ n cos $ „20 (a - - £) b a 78 1 1 8 37 _ 8 _

A special procedure has been built in to place and lift loads on the deck.

If the crane hook is above its own deck, the values A0 5 and Bq are adjusted when the size of the load G changes.

Fig. 3 further schematically shows the teaching operation of the data in the computer. in Dept. I (input recorded values),

Div. II (comparison with calculated fixed program values) and dept. IIl! (conversion into valve command data, the latter 10 being denoted by VA and Vg).

Example of the compensation procedure.

Fig. 6 shows that the crane 14, of which only the boom is shown, is located at the ends of a transverse axis of the working platform near an end side thereof, as in the other figures, above column 6. .

For the sake of simplicity, one crane is assumed, whereby the own weight is not compensated (see fig. 5 and 6).

We can then use the simple formulas for the calculation of the compensation forces, which were included in the introductory section under the heading "Compensation system with two compensation forces".

To calculate the position of the load we use the swing angle and radius of the crane, and assume that the center of the crane coincides with the working line of compensation force A, ie with the 25 axis of the column 6 under the crane 14 then holds: x = a - R cos ϋ y = b + E sin $ A = s -JG (2 - - cosÜ + E sinÜ) a -ff B 5 £ G (- - oosO - ^ sint ') so 50 I / e can now assume, as a number example, a = ^ 3 mba 3k m.

Volume of all reservoirs: kOOQ m ^ ”_ Crane capacity: G = 2700 tons at R = 32 m._ 7811837

Claims (10)

5 Br, a load of 2700 tons of a platform outside the vessel is now included. It follows from the formulas that the desired compensation * forces are A 3970.6 tons and B-1270.6 tons. The horizontal position is maintained, because valve A ^ 3970.6 m3 of water is discharged while the load is being taken up, while valve B ^ \ 270.6 m ^ is supplying water. The filling of the reservoirs then present is indicated in the second box from the top in fig. 6. The crane now pivots from position I to position II, for which it can be calculated from the formulas that the desired compensation forces are in position II? 15 A = 3704.7 tons and B = 1004.7 tons. The horizontal position of the vessel is maintained, because during the maneuver valve A2 introduces 265.9 m3 of water and valve B> j 2275 »3 emits water. The resulting reservoir filling is indicated in the third box of Fig. 6. 20 After the load has been deposited from the position II on a support surface outside the vessel, A and B, as in the starting position, are equal to 0. The horizontal position is maintained, because the aforementioned compensation forces are removed during the deposition. for which valve A2 has to let in 3704.7 ra ^ water and valve B2 has to let in 1004.7 o3 water. The resulting filling of the water reservoirs is shown in the 4th box of Fig. 7. 5_2_N_C_L_ïï_S_Ï_5_§ 1. Stabilization system for a work vessel with underwater hulls sweeped in the working state on which hollow columns are placed, which support a work platform located above the water level with one or down heavy cranes, the stabilization system comprising water ballast reservoirs located above and below the ambient water level » n On the one hand, the outpouring of water from the above-water reservoirs 781 1 8 37, on the other hand, the inlet of water into the underwater ballast reservoirs is selectively controlled depending on the moment of moment of the crane loading torque during the load maneuver, characterized in that the control valves of the underwater ballast chambers have 5 water inlet valves are in those rooms, which are incidentally closed off from the ambient water. 2. Stabilizing system according to claim 1, characterized in that a pumping device is provided, with which the water can be pumped from the underwater ballast chambers to the upper water ballast chambers. Stabilization system according to claim 1 or 2, characterized in that only at the ends of a transverse axis of the vessel on one end side of the working platform is a column mounted on an underwater row, provided with an upper and underwater ballast chamber, each of the cranes being mounted above one of these columns. k. Stabilization system according to claim 3, characterized in that the center of the crane coincides substantially with the common axis of the upper and underwater reservoir in the column situated below the crane. Stabilizing system according to claim 3 or characterized in that during a crane maneuver during the outboard lifting of a load by means of a crane arm extending in the longitudinal direction of the vessel, an above-water ballast chamber is emptied in dependence on the increasing moment load and additionally a part of the lower ballast chamber at the opposite shaft end is filled by opening its water admission valve, then stabilization is effected by water outlet from the shaft end at the latter shaft during pivoting of the crane through an angle of 90 ° to a second outboard position located above ballast chamber and additional inlet control of water in the lower ballast chamber located under the active crane, while when the load is put down after the slewing has been completed, stabilization is effected by water admission into the lower ballast chambers under the active crane and admitting water in the lower ballast room r at the opposite transverse shaft end. 781 1 8 37 Stabilizing system according to any one of the preceding claims, characterized in that the compensation forces to be obtained for stabilization by the water outlet from the upper ballast chambers and the water inlet in the lower ballast chambers during a crane maneuver are continuously calculated as a function of the crane for the given crane maneuver. arm position and crane load required water level or volumes in the water ballast chambers and the valves concerned are activated as a function of the difference between the desired and measured values of the water level or water volume in the water ballast chambers concerned. * 7 * Stabilization system according to claim 6, characterized in that a volume control is applied, the position of the valves being measured moment by moment, the valve characteristic being entered as fixed data and the volume flow being integrated over time until the desired volume for the compensation forces to be obtained for each of the water ballast chambers has been reached. Stabilizing system according to claim 6 or 7, characterized in that several valves of different capacity are used per water ballast chamber and the choice and number of activated valves per water ballast chamber during the crane maneuver is determined at any time as a function of the difference between the desired value and the measured value of the water level or water volume in the water ballast chambers concerned. 7811837