CN111307371B - Ship gravity center measuring method - Google Patents
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- CN111307371B CN111307371B CN202010217314.2A CN202010217314A CN111307371B CN 111307371 B CN111307371 B CN 111307371B CN 202010217314 A CN202010217314 A CN 202010217314A CN 111307371 B CN111307371 B CN 111307371B
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Abstract
The embodiment of the invention discloses a method for measuring the gravity center of a ship, which comprises the following steps: step 1: a preparation stage; step 2: measuring the weight and the longitudinal position of the gravity center of the ship body; and step 3: measuring the vertical coordinate of the gravity center of the ship body; the method for measuring the actual weight and the gravity center position of the small ship by using the crane is simple and easy to implement, and a bracket is not required to be manufactured. Small ship installation sites, whether indoor or outdoor, are usually provided with cranes, and the hoisting capacity of the crane is only required to exceed 1/2 of the weight of a ship body; the crane has the capability of parallel movement and vertical hoisting originally, the center of gravity of the ship body is below a hoisting point, the ship body is not easy to overturn during hoisting, and the safety is greatly improved.
Description
Technical Field
The invention relates to the technical field of ship inspection, in particular to a ship gravity center measuring method.
Background
The measurement of the actual weight and the gravity center position (longitudinal coordinate and vertical coordinate) of the small ship is an important basis for ship inspection and ship stability checking calculation. The common weighing test method is that a front support and a rear support are arranged at the bottom of a ship, and the weight and the longitudinal gravity center position of the ship are determined according to the moment balance principle by measuring the stress at the support points. And to measure the vertical coordinate of the gravity center of the ship, the vertical position of one supporting point needs to be adjusted, the stress of the other supporting point, a group of position values and the vertical displacement of the lifting fulcrum are measured, and the vertical coordinate of the gravity center of the ship is calculated.
Although the method for measuring the actual weight and the longitudinal coordinate and the vertical coordinate of the center of gravity of the small ship is feasible, two moulding beds are required to be manufactured and installed at the bottom of the ship, two supports are simultaneously manufactured, one support is required to be capable of moving longitudinally and lifting vertically, weighing sensors are required to be installed on the two supports, and the workload for manufacturing the moulding beds and the supports is large. When the supporting points are lifted, the distance between the two supporting points is shortened, a movable support is needed, and a support capable of vertically lifting is manufactured at the same time. However, the lifting of the support needs to be moved simultaneously, so that the operation is difficult, the gravity center of the ship body is higher than the fulcrum, and if the ship body is carelessly operated, the overturning of the ship body is easy to happen, and the equipment and personal safety are endangered.
Disclosure of Invention
The invention aims to provide a method for measuring the center of gravity of a ship, which aims to solve the problems in the prior art.
The embodiment of the invention provides a method for measuring the gravity center of a ship, which comprises the following steps:
step 1: preparation phase
1) Firstly, manufacturing an arc-shaped base on a landing pad at the bottom of the lifting platform and fixing;
2) manufacturing a hanging beam, respectively hoisting left and right lifting lugs at the bow end and the stern end of the lifting platform by using the hanging beam and a hook during weighing, and hanging the middle point of the hanging beam on a lifting hook of a crane through a weighing sensor;
step 2: determining the longitudinal position of the weight and center of gravity of a ship
A. Measuring the longitudinal distance La from a bow end lifting lug to the center of a stern end landing pad, the distance Lb from the stern end lifting lug to the center of the bow end landing pad and the distance L from the stern end lifting lug to the center of the front landing pad and the center of the rear landing pad, setting the distance from the center of gravity of the lift platform to the center of the bow end landing pad as X, and setting the weight of the lift platform as delta;
B. vertically hoisting the bow end lifting lug, reading the weighing number, subtracting the weight of the hanging beam and the accessory, and taking the value Ra;
C. vertically hoisting a tail end lifting lug, reading the weighing number, subtracting the weight of the hanging beam and accessories, and taking the value Rb;
from the moment balance condition, the following equation can be listed:
(1) formula (3) can be rewritten as RaLa ═ DeltaL-DeltaX … … … … … … … … …
(2) And (3) add: RaLa + RbRb ═ DeltaL
Thus, the weight of the lift platform:
from (2), the barycentric position can be found:
and step 3: determining the vertical coordinates of the center of gravity of the hull
a. Measuring the distance h1 from the eye of the stern end lifting lug to the bottom of the ship;
b. lifting a stern end lifting lug vertically, measuring the lifting height h2, reading the weighing number, subtracting the weight of a lifting beam and accessories, taking the value Rb, and taking the included angle phi between the ship body and the ground after the ship body is lifted on one side, then:
Rb(Lb-h1tanφ)cosφ＝△(X-ZGtanφ)cosφ
elimination of cos phi, Rb (Lb-h)1tanφ)＝△X-△ZGtanφ
Obtaining a vertical coordinate Delta Z from the center of gravity of the ship body to the bottom of the shipG：
Further, the arc-shaped base is selected to be the arc curvature radius, so that the circle center is located at the joint of the center of the landing pad and the ship bottom.
Further, the lifting beam and the lifting accessory are weighed firstly and deducted when the weight of the lifting platform is calculated.
Furthermore, the weighing sensor is a tension sensor with the rated weighing capacity of more than 15 tons.
Further, the tape measure with the length of 10 meters is selected, when the vertical size of the ship body is difficult to measure, the theodolite can be used for measuring, and a heavy hammer is hung below the lifting hook and is parallel to the steel wire rope to serve as a reference for vertical effect of lifting force.
Compared with the prior art, the invention has the beneficial effects that:
the method for measuring the actual weight and the gravity center position of the small ship by using the crane is simple and easy to implement, and a bracket is not required to be manufactured. Small ship installation sites, whether indoor or outdoor, are usually provided with cranes, and the hoisting capacity of the crane is only required to exceed 1/2 of the weight of a ship body; the crane has the capability of parallel movement and vertical hoisting originally, the center of gravity of the ship body is below a hoisting point, the ship body is not easy to overturn during hoisting, and the safety is greatly improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic view of a configuration for measuring the weight and longitudinal position of the center of gravity of a hull in an embodiment of the invention;
FIG. 2 is a schematic structural diagram of measuring the vertical coordinate of the gravity center of the ship body in the embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1-2, the method for measuring the center of gravity of a ship in the present embodiment includes the following steps:
step 1: preparation phase
1) Firstly, manufacturing an arc-shaped base on a landing pad at the bottom of the lifting platform and fixing; the arc-shaped base 200 is selected to enable the circle center to fall on the joint of the center of the landing pad and the ship bottom for the curvature radius of the arc, so that the arrangement ensures that the supporting reaction direction of the landing point passes through the upper center of the landing pad when the front lifting lug and the rear lifting lug are lifted, and the sizes of the landing pad and the arc-shaped base below can be omitted when the vertical coordinate of the gravity center is calculated.
2) Manufacturing a hanging beam, wherein the hanging beam and a hook are used for respectively lifting left and right lifting lugs at the bow end and the stern end of the lifting platform during weighing, the middle point of the hanging beam is hung on a lifting hook of a crane through a weighing sensor, the weighing sensor selects a tension sensor with the rated weight larger than 15 tons and is connected with a display, the hanging beam and a lifting accessory are weighed firstly and deducted when the weight of the lifting platform is calculated; the length of the measuring tape can be 10 meters, when the vertical dimension of the ship body is difficult to measure, the measuring tape can be measured by a theodolite, and a heavy hammer is hung below a lifting hook and is parallel to a steel wire rope to be used as a reference for vertical action (moving a crane) of lifting force;
step 2: determining the longitudinal position of the weight and center of gravity of a ship
A. Measuring the longitudinal distance La from a bow end lifting lug to the center of a stern end landing pad, the distance Lb from the stern end lifting lug to the center of the bow end landing pad and the distance L from the stern end lifting lug to the center of the front landing pad and the center of the rear landing pad, setting the distance from the center of gravity of the lift platform to the center of the bow end landing pad as X, and setting the weight of the lift platform as delta;
B. vertically hoisting the bow end lifting lug, reading the weighing number, subtracting the weight of the hanging beam and the accessory, and taking the value Ra;
C. vertically hoisting a tail end lifting lug, reading the weighing number, subtracting the weight of the hanging beam and accessories, and taking the value Rb;
from the moment balance condition, the following equation can be listed:
(1) formula (3) can be rewritten as RaLa ═ DeltaL-DeltaX … … … … … … … … …
(2) And (3) add: RaLa + RbRb ═ DeltaL
Thus, the weight of the lift platform:
from (2), the barycentric position can be found:
and step 3: determining the vertical coordinates of the center of gravity of the hull
a. Measuring the distance h1 from the eye of the stern end lifting lug to the bottom of the ship;
b. lifting a stern end lifting lug vertically, measuring the lifting height h2, reading the weighing number, subtracting the weight of a lifting beam and accessories, taking the value Rb, and taking the included angle phi between the ship body and the ground after the ship body is lifted on one side, then:
Rb(Lb-h1tanφ)cosφ＝△(X-ZGtanφ)cosφ
elimination of cos phi, Rb (Lb-h)1tanφ)＝△X-△ZGtanφ
Obtaining a vertical coordinate Delta Z from the center of gravity of the ship body to the bottom of the shipG：
The invention is simple and easy to use, and does not need to manufacture a bracket. Small ship installation sites, whether indoor or outdoor, are usually provided with cranes, and the hoisting capacity of the crane is only required to exceed 1/2 of the weight of a ship body; the crane has the capability of parallel movement and vertical hoisting originally, the center of gravity of the ship body is below a hoisting point, the ship body is not easy to overturn during hoisting, and the safety is greatly improved. The apron of a special ship such as a hovercraft drags the ground at ordinary times, and when the gravity center is measured, the apron needs to be lifted off the ground, so that the special elevator for lifting the ship body when the apron is installed and maintained can be used for lifting the ship body, and the test task can be finished. However, such elevators are typically only capable of lifting and not translating, and therefore cannot be used to determine the vertical coordinate of the center of gravity. The additional arrangement of the movable support on the existing elevator is easy to cause the side-turning accident of the elevator. Therefore, the determination of the position of the center of gravity of the hovercraft using a crane apparatus is almost the only method.
The invention is used for the determination of the gravity center position of the air cushion platform, the auxiliary pivot is simple and reasonable to manufacture, the use of the crane and the suspended digital weighing sensor is convenient and accurate, the parallel movement of the crane and the lifting of the lifting point are convenient and reliable, the parallel movement is easy to perform when the crane is lifted by the plumb bob for inspection and measurement, and the data is correct. Since the working method is efficient, all the measurement work is completed in only 3 hours except for the preparation work.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (5)
1. A method for measuring the center of gravity of a ship comprises the following steps:
step 1: preparation phase
1) Firstly, manufacturing an arc-shaped base on a landing pad at the bottom of the lifting platform and fixing;
2) manufacturing a hanging beam, respectively hoisting left and right lifting lugs at the bow end and the stern end of the lifting platform by using the hanging beam and a hook during weighing, and hanging the middle point of the hanging beam on a lifting hook of a crane through a weighing sensor;
step 2: determining the longitudinal position of the weight and center of gravity of a ship
A. Measuring the longitudinal distance La from a bow end lifting lug to the center of a stern end landing pad, the distance Lb from the stern end lifting lug to the center of the bow end landing pad and the distance L from the stern end lifting lug to the center of the front landing pad and the center of the rear landing pad, setting the distance from the center of gravity of the lift platform to the center of the bow end landing pad as X, and setting the weight of the lift platform as delta;
B. vertically hoisting the bow end lifting lug, reading the weighing number, subtracting the weight of the hanging beam and the accessory, and taking the value Ra;
C. vertically hoisting a tail end lifting lug, reading the weighing number, subtracting the weight of the hanging beam and accessories, and taking the value Rb;
from the moment balance condition, the following equation can be listed:
(1) formula (3) can be rewritten as RaLa ═ DeltaL-DeltaX … … … … … … … … …
(2) And (3) add: RaLa + RbRb ═ DeltaL
Thus, the weight of the lift platform:
from (2), the barycentric position can be found:
and step 3: determining the vertical coordinates of the center of gravity of the hull
a. Measuring the distance h from the eye of the lifting lug at the stern end to the bottom of the ship1；
b. Vertically hoisting the tail end lifting lug and measuring the hoisting height h2Reading the weighing number, subtracting the weight of the hanging beam and the accessory, taking the value Rb, and taking the included angle between the ship body and the ground after one side of the ship body is hung as phi:
Rb(Lb-h1tanφ)cosφ＝△(X-ZGtanφ)cosφ
elimination of cos phi, Rb (Lb-h)1tanφ)＝△X-△ZGtanφ
Obtain a ship bodyVertical coordinate Delta Z from center of gravity to bottom of shipG：
2. The method of claim 1, wherein the radius of curvature of the arc of the base is selected so that the center of the arc of the base is at the junction of the center of the landing pad and the bottom of the vessel.
3. The method as claimed in claim 1, wherein the weight of the lifting beam and the lifting attachment are weighed and subtracted when calculating the weight of the platform.
4. The method for measuring the center of gravity of the ship according to claim 1, wherein the weighing sensor is a tension sensor with a rated weighing capacity of more than 15 tons.
5. The method as claimed in claim 1, wherein when the vertical dimension of the hull is difficult to measure, it can be measured by theodolite, and the weight is hung under the lifting hook and parallel to the steel cable as the reference for vertical action of the lifting force.
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| CN112598976B (en) * | 2020-12-17 | 2021-10-08 | 大连理工大学 | Experiment teaching device and method for measuring three-dimensional space coordinate of center of gravity of object |
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| SU1211138A1 (en) * | 1984-04-27 | 1986-02-15 | Предприятие П/Я В-8458 | Method of determining z-axis of low-tonnage ship mass centre |
| RU2499722C1 (en) * | 2012-10-25 | 2013-11-27 | Федеральное Государственное Автономное Образовательное Учреждение Высшего Профессионального Образования "Дальневосточный Федеральный Университет" (Двфу) | Method of ship weight determination and z-coordinates of ship center of gravity |
| CN103592078B (en) * | 2013-11-28 | 2016-01-06 | 航天科工哈尔滨风华有限公司 | A kind of large-size large-tonnage cylindrical shape or the radial centroid measurement instrument of cylindrical work |
| WO2016076458A1 (en) * | 2014-11-13 | 2016-05-19 | 한국해양연구원 | Device for measuring pitching moment of inertia and height of center of gravity of model ship |
| CN105136392B (en) * | 2015-09-25 | 2018-06-26 | 中航电测仪器股份有限公司 | A kind of dirigible center of gravity measurement equipment and measuring method |
| CN105784276B (en) * | 2016-05-11 | 2017-12-26 | 大连理工大学 | The polyaxial inertia automatic measurement of marine structure thing test model and adjusting means and its application method |
| CN106017800A (en) * | 2016-08-02 | 2016-10-12 | 江苏海事职业技术学院 | General cargo ship gravity monitoring method |
| KR101945396B1 (en) * | 2016-09-27 | 2019-02-07 | 삼성중공업 주식회사 | Apparatus for measuring a center of gravity |
| CN108106781A (en) * | 2017-12-06 | 2018-06-01 | 哈尔滨工程大学 | A kind of ship model gravity center measurement device |
| CN110082033B (en) * | 2018-12-11 | 2020-12-22 | 自然资源部第一海洋研究所 | Device and method for measuring gravity center of water carrier in motion state |
| CN109916557A (en) * | 2019-04-09 | 2019-06-21 | 清华大学深圳研究生院 | A kind of structure measurement device |
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